voc-fria linoljebaserade tr¤skyddsprodukter voc-free linseed oil

Nr: 01003Title

VOC-fria linoljebaserade träskyddsprodukter

VOC-free linseed oil based woodprotection products(VOCFRILIN)

Final technical report

2001-07-01 – 2003-12-31

Eva Wallström,EnPro ApS, Köpenhamn, [email protected] Svensson, Svenska Lantmännen, Stockholm, [email protected]

VOCFRILIN – NI-project 01003

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Content Final Report1 Summary ................................................................................................................................ 3

1.1 Summary of the project including its relevance to Nordic industry.................................................................. 31.2 Technical summary ............................................................................................................................................. 4

2 Participants............................................................................................................................. 53 Background ............................................................................................................................ 7

3.1 Project objectives ................................................................................................................................................. 84 Air-drying coating systems ..................................................................................................... 8

4.1 Vegetable oils ....................................................................................................................................................... 84.2 The oxidative drying mechanism ...................................................................................................................... 104.3 Driers ................................................................................................................................................................. 114.4 Anti-skinning agents.......................................................................................................................................... 144.5 Binders for air-drying coating systems .............................................................................................................. 144.6 Alkyd binders and their uses ............................................................................................................................. 174.7 Prospect for the use of air-drying coatings........................................................................................................ 19

5 Choice of raw materials........................................................................................................ 205.1 Laboratory scale production of raw materials .................................................................................................. 215.2 Methods for characterization of raw materials ................................................................................................. 215.3 Characterization of raw materials ..................................................................................................................... 235.4 Summary and conclusions ................................................................................................................................. 26

6 Model formulations for floor oils......................................................................................... 266.1 Choice of drier system....................................................................................................................................... 276.2 Rheology............................................................................................................................................................ 286.3 Drying time of prepared samples ...................................................................................................................... 286.4 Oil penetration of wood panels......................................................................................................................... 296.5 Surface tension ................................................................................................................................................... 306.6 Water Pickup of floor oils ................................................................................................................................. 306.7 Summary and conclusions ................................................................................................................................. 31

7 Analysis of drying mechanisms ............................................................................................ 317.1 Comparison between linseed oils rich in linoleic acid vs linseed oils rich in linolenic acid ............................ 317.2 Methyl esters as reactive diluents in linseed oil based coatings. ....................................................................... 317.3 Emissions from the drying process ................................................................................................................... 32

8 Model systems for wood primer........................................................................................... 368.1 Summary and conclusions ................................................................................................................................. 37

9 Model systems for outdoor paint.......................................................................................... 379.1 Choice of formulations, with and without pigment......................................................................................... 379.2 Choice of drier system....................................................................................................................................... 389.3 Physical characterization of model systems...................................................................................................... 389.4 Characterisation of chosen model systems, 2nd screening................................................................................. 409.5 Summary and conclusions ................................................................................................................................. 41

10 Accelerated testing of durability........................................................................................... 4210.1 QUV-testing.................................................................................................................................................. 4210.2 Summary and conclusions ............................................................................................................................ 44

11 Evaluation of linseed raw materials for wood protection..................................................... 4411.1 General trends............................................................................................................................................... 4411.2 Need for development .................................................................................................................................. 4411.3 Expectations to future................................................................................................................................... 44

12 References............................................................................................................................. 4513 Publications .......................................................................................................................... 4614 Conference presentations ..................................................................................................... 46


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1 Summary

1.1 Summary of the project including its relevance to Nordic industry

The objective of the project has been to develop linseed oil-based products for wood protection freefrom volatile organic compounds (VOC). The more specific problems that have been addressedconcern the drawbacks that can be associated with this type of products, such as yellowing, ageing,slow drying and malodorous emissions.

Firstly, new types of linseed oil products were produced and characterised; 1) a new linseed oil(Purolin ®) with a modified fatty acid composition, 2) a low viscous binder (Linutin ®) based onlinseed oil, suitable as a reactive diluent in the products, and 3) alkyd resins based on traditionallinseed oil and Purolin. Instead of diluting these with white spirits (a VOC), Linutin was used as thediluent.

During the first year un-pigmented products were investigated. We found that the new oil hadsuperior penetration ability in wood but a slower drying (when tested on glass). The new oildisplayed less yellowing during storage. It was possible to replace VOC with Linutin to get anacceptable viscosity suitable for wood protection. However, the major problem appeared to be howto apply a sufficient small amount of oil on the surface. A solvent-free product will quickly saturatethe outmost surface of the wood, leading to an ”oily” appearance. These products typically containmore than 50% volatile solvents, so that a very small amount of oil is applied at each application.The paint-producing companies in the project are working with users of e.g. floor oils, to find waysof changing the applications methods of oils to enable a use of VOC-free products.

During recent years there has been a general belief from users of linseed oil paints that emissionsfrom drying paints can expose a serious occupational health risk. In the project the emissions fromdrying oils and paints have been extensively studied. When linseed oil is used under normalpainting conditions the amount of aldehydes are much lower than the health limits. The new oildisplayed a different chemical emission profile; emitting higher molecular weight (C6) and lesssmelling compounds. The results from these studies have been communicated to worker’s unionsand employer organisations.

During the last year of the project the work was focused on pigmented paints for wood protection,typically a white outdoor paint. It was early found that when a VOC-solvent was replaced withLinutin, and Purolin used instead of traditional oil, the paint film become softer, discoloured andmatt. A very extensive formulation work was needed to solve these problems. In this work severaldifferent types of driers, fillers and types of alkyds were tested. The work resulted in a model recipethat yielded a paint of acceptable hardness, colour, and gloss. This paint is now tested in acceleratedtest in the industry.

The project has created a network of companies involved in the production of linseed oil basedpaints and products. The need for product development and increased knowledge was the startingpoint of the project. Throughout the project the experience and knowledge in the field have beenexchanged between the partners. The final project results, which are model recipes for formulations,


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can be used by the partners in their future development of paint and oil products. The open resultswill also be communicated to other paint producers in order to increase the use of the new linseedoils.

In combination with the increasing popularity for renewable materials (wood and wood protection),this will mean that the Nordic industry can use the project results to improve the competitiveness.New market shares in other coating sectors for reactive diluents based on renewable materials canbe also be expected as an outcome of the project. In addition, a successful exploitation of the resultscan support a sustainable industry for preparing linseed oil of high quality based on a Nordic naturalmaterial. By offering customer-adapted oil products, as well as a reliable expertise about theproducts, the competitiveness for the Nordic linseed oil against imported oils will grow.

1.2 Technical summary

The raw materials produced was characterised and compared. The basic properties of the rawmaterials were analysed, e.g. fatty acid composition, viscosity, peroxide value, colour. Purolindiffers from traditional linseed oil in that it is low in linolenic acid (C18:3) and high in linoleic acid(C18:2). The alkyd based on Purolin diluted in Linutin gives a very soft film, which can beinterpreted as that Linutin acts as softening agent. This result indicates that an alkyd with a low oillength could be used. When producing a urethane alkyd with Purolin instead of linseed oil gives aharder film than expected. It should be noted that it was not possible to produce a Urethane alkyd,which was diluted with Linutin.

The modified linseed oil (Purolin) has a number of advantages. It seems to penetrate better thantraditional linseed oil (up to 50% more). The oil penetration in wood shows surprisingly that theviscosity of the oil is not related to the ability to penetrate wood. The water up-take (floor oils) isless than for the traditional linseed oil. The formulated prototype paints represent both traditionallinseed oil paint as well as Purolin-based paint formulated on boiled oil and alkyd. Most of theprototypes are high solids and some of them have 100 % dry matter. Two drier systems worked wellwith the Purolin paints: One system with Co, Al and Ca, and one system with Mn, Al and Ca. TheAl-drier is normally used for high solid products. The linseed oil products work well with the Co-system, but not with the Mn-system.

The Purolin-based prototypes become softer with the Mn drier system, but got a higher gloss. Thegloss becomes even higher than the commercial products. It also clear that Zinc-oxide gives aharder surface which makes the hardness close to commercial linseed oil paint. It is clear that thelinseed methyl ester softens the product. If a short oil alkyd is used together with Linutin it ispossible to get drying and a surface that is tack-free. The QUV tests show that there are somePurolin-based coatings that are rather good. There are also here indications on that the Mn-system isto prefer in the Purolin-based coatings.

Analysis of the curing performance of linseed oil coatings is changed when changing the fatty acidpattern in the oils. Traditional linseed oil, rich in linolenic acid, dries rapidly but the coating suffersfrom high degrees of residual unsaturation in the cured film. Purolin produced slightly softer filmsbut with a significantly lower amount of residual unsaturation, no problem with skin formation, andgood through cure. The difference in curing affects the long-term durability and colourfastness.


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Analysis of emissions show that there are differences between the emission processes of a linolenicand a linoleic acid rich oil there a change to hexanal being the most abundant emittant instead ofpropanal. The time processes are also different. The emission of the floor oil with the traditionallinseed oil peaked somewhere between three and eight hours whereas the Purolin had its peakemission somewhere between 16 and 24 hours after application of the paint.

These analytical results explain the practical results with regard to that Purolin gives a softer film.But it also explains why the two types of oil need different drier systems. The drying time for thePurolin based paint is nearly 24 hours with the Mn-drier system. The drying of the best formulationscan without doubt be optimised further.

2 ParticipantsProject coordinator:Martin Svensson [email protected] Baeling [email protected] Lantmännen www.lantmannen.seBox 30192SE-104 25 StockholmSVERIGETel: 0046-8-657 4200, Fax: 0046-8-618 6932

Eva Wallström [email protected] Pilemand [email protected] ApS www.enpro.dkLersø Parkallé 42DK-2100 Köbenhavn ÖDANMARKtel 0045-39 27 28 78 fax: 0045-39 18 36 90

Mats Johansson [email protected] Tekniska Högskolan (KTH)PolymerteknologiSE-100 44 StockholmSVERIGEtel 0046-8 790 9287 fax: 0046-8 100 775

Barbro Andersson [email protected]å UniversitetKemiska Institutionen – MiljökemiSE-901 87 UmeåSVERIGEtel 0046-90 786 52 47 fax: 0046-90 12 81 33

Mikael Bergström [email protected]ödra Timber AB www.sodra.seSkogsuddenS-35189 VäxjöSVERIGETel: 0046-470 89 000 Fax: 0046-470 89 219

Hans Claesson [email protected]


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Engwall o. Claesson AB www.eoc.seBox 434SE-124 04 BandhagenSVERIGETel: 0046-8 86 03 50 Fax: 0046-99 90 03

Jan Ekstedt [email protected]ätek AB, Institutet för träteknisk forskningDrottning Kristinas v.67Box 5609114 86 StockholmSVERIGEtel 0046 –8-762 1800

Poul Bastholm, [email protected]ügger A/S www.flugger.comIslevdalvej 1512610 RødovreDANMARKtel 0045-70 15 15 05 fax: 0045-44 54 15 05

Anders Frisk [email protected]ügger ABGrönkullen517 81 Bollebygdtel. 0046-33-700 23 80 fax.0046-33-700 2465

Irene Horn [email protected] ApS www.horn-aps.dkSortebjergvej 2DK-6640 LunderskovDANMARKtel 0045-75 58 50 87 fax: 0046-75 58 50 98

Anders Gottlieb [email protected] Industrier A/S www.junckers.dkVærftsvej 4DK-4600 KøgeDANMARKTel: 0045-56 65 18 95 Fax: 0045-56 67 33 50

Ralf Åkerlund [email protected] Conralex LtdJaktvägen 5DFI-106 50 EkenäsFINLANDtel 00358-19 241 4445 fax: 00358-19 241 4446

Klaus Nygaard Andersen [email protected] Specialties Nordic A/SØstmarken 32860 SøborgDANMARKTel: 0045-39 69 33 22 Fax: 0045-39 69 71 55

Sari Uunila [email protected]


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Uulatuote Oy www.uula.fiFI-32920 KauvatsaFINLANDtel 00358-2 529 5000 fax: 00358-2 529 5011

Pär Fjällström [email protected]å UniversitetKemiska Institutionen – MiljökemiSE-901 87 UmeåSVERIGEtel 0046-90 786 52 47

Cecilia Stenberg [email protected] Tekniska Högskolan (KTH)PolymerteknologiSE-100 44 StockholmSVERIGEtel 0046-8 790 9287

Åsa Rydell [email protected] Industriella ProduktionssystemVäxjö Universitet351 95 Växjötel 0470-70 8126

3 Background

Vegetable oils are widely used within the coating industry. Coatings containing drying oils and fattyacid derivatives from drying or semi-drying oils such as alkyds, epoxy esters and urethane alkydsdry by oxidative cross-linking. Such systems are called air-drying or oxidative drying coatings.

Of the vegetable oils used in coatings, linseed oil has the longest tradition both by itself, or modifiedin coatings such as alkyd. The advantage with linseed oil is that it is a relatively inexpensiveresource for drying oil and that it provides good protection of wood where the penetration ability ofthe oil into the wood is superior to other alternatives. However, there are disadvantages such asproblems with yellowing, poor long-term stability, and rather soft films. This has been the majorreason for the replacement of linseed oil by modern synthetic coatings such as alkyds and latexcoatings in wood protection.

Improved knowledge by modern crop development on plant breeding and developed productiontechniques has also enabled the possibility to design the oil structure of linseed oils. This hasresulted in linseed varieties with higher yields, controlled oil content and increased content ofunsaturated fatty acids (higher iodine values). In recent years a new line of plant breeding has beenemployed in order to obtain edible linseed oil, i.e. in which the concentration of the easily oxidisedand unpalatable linolenic acid has been minimised. By removing as much as possible of this fattyacid, the risk for unpleasant rancidity products is reduced. However, this also leads to a reducediodine value, hence, oil that may be regarded as unsuitable in paint and coating applications.


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The background of this project was to investigate the initial observations that this new type oflinseed oil could overcome the problems of yellowing and malodorous emissions associated withtraditional linseed oil. Furthermore, by inter-esterification the linseed oil could be modified to alow viscous but yet drying oil, potentially suitable as a “diluent” in paints.

These two raw materials were the basics for trying to develop VOC-free vegetable oil basedcoatings.

3.1 Project objectives

The project objectives are to develop modern linseed oil based wood protections products with ahigher quality than the corresponding traditional products containing volatile organic solvents.Quantifiable objectives are shorter drying times, less yellowing, lower emissions and increaseddurability. To achieve this a new type of reactive diluent based on an esterified linseed oil as wellas a linseed oil of modified composition will be investigated.

4 Air-drying coating systems

Coatings, which are able to dry by oxidative cross-linking, are classified as air-drying or oxidativedrying coatings. Air-drying coating systems contain binders as oils, alkyds, epoxy esters andurethane alkyds, which are all based on vegetable oils or vegetable oil derivatives. On a volumebasis alkyds are by far the most important of the air-drying binders.

4.1 Vegetable oils

Vegetable oil molecules are triglycerides, which constitutes a glycerol backbone combined withdifferent fatty acids. The fatty acids present in vegetable oils have varying hydrocarbon chainlengths even within the same oil. The chain of a fatty acid does commonly contain an even numberof carbon atoms ranging from 10 to 20 including the carbon atom in the acid group (-COOH). Thefatty acids combined with glycerol determine the specific properties of vegetable oils and as thefatty acid combination differs from one type of vegetable oil to another so do the properties. Thechemical structures of vegetable oils, glycerol and fatty acids are schematically indicated in figure2.1.

CH2-O-COR1 CH2OH

CH -O-COR2 CHOH R1COOH

CH2-O-COR3 CH2OH

vegetable oil glycerol fatty acid

Figure 2.1 A vegetable oil is a triglyceride, consisting of glycerol and fatty acids. Thefatty acids are symbolised by R1, R2 and R3 indicating that vegetable oil

contains fatty acids with different chain length. The fatty acids can either besaturated or unsaturated.


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The fatty acids can either be saturated containing no double bonds, or they can be unsaturatedcontaining one or more double bonds. The presence of double bonds makes the oils reactive, as thedouble bonds are able to polymerise (cross-link) when exposed to oxygen. This ability to cross-linkmake unsaturated oils able to form a solid, coherent and adherent film when spread on a surface andexposed to oxygen in the air.

The drying properties of oils depend on the degree of unsaturation. The more unsaturated the oil isthe better the drying properties are. Oils are usually classified as drying, semi-drying or non-dryingoils according to their ability to dry in air. Over a period of time drying oils will form a tack-freefilm whereas semi-drying oils form films will never become completely tack-free. Non-drying oilsare unable to react to form a cross-linked film by air oxidation as they mainly consist of saturatedfatty acids, which have no drying properties3. The non-drying oil types or derivatives of non-dryingoils are therefore not being used for air-drying binders.

Semi-drying oils contain acids with only one or two double bonds, for instance soybean oil,sunflower oil, tall oil or safflower oil, whereas drying oils are highly unsaturated oils, consisting offatty acids containing two or three double bonds. Linseed oil, tung oil, and oiticica oil are allclassified as drying oils.

Although drying oils, especially the refined ones, are able to form films in their unmodified form theprocess is still fairly slow. In most cases they are therefore modified to increase molecular weightand viscosity before using them in coatings to improve drying time, as well as the overall filmforming properties. An increased initial molecular weight means that less cross-linking is necessaryin order to obtain a coherent film and therefore the drying time is reduced.

The oils can be modified either by thermal treatments, which polymerise the oil molecules, or bychemical treatments, in which the oil molecules polymerise with other chemical compounds.

Commercially exploited seeds such as soya, rapeseed, sunflower and linseed have been the subjectof many years of breeding programmes to obtain oils with particular fatty acid patterns. In additionto breeding efforts on traditional oil crops, work is being done to domesticate alternative oil richplants that may yield new potentially useful fatty acids.

In recent years genetic engineering approaches have been considered to make a contribution toexpanding the available materials for “non-food” uses, such as increasing the concentration of aparticular fatty acid or introducing new fatty acids. In the latter context an abundance of unusualfatty acids can be found in plants from nature. In some cases the genes responsible for the synthesisof these have been identified and genetic engineering is under way to transfer the genes and expressthem in plants suitable for cultivation. This may in the future lead to an even greater range ofdrying oils available for the coating industry and an increased need for basic studies of dryingproperties of fatty acids and their esters.


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4.2 The oxidative drying mechanism

All coating types containing unsaturated vegetable oils or unsaturated vegetable oil derivatives dryby oxidative cross-linking. The drying mechanism of the process is very complex and although theprincipal reactions involved in the oxidative cross-linking are known, the total mechanism is stillnot fully established. However, it is accepted that the first steps in oxidative drying involvehydroperoxide formation. This initial peroxide formation is followed by decomposition of peroxidesto form free radicals, which then initiate polymerisation2,3,4.

The drying mechanism for air-drying systems is described here in general terms. The chemicalmechanisms presented are suggested in the open literature and they are largely based on work withmodel compounds, which may not always be easily related to the more complex polymer systemsused in practice3.

The first stage of drying is the formation of peroxides. Both conjugated and non-conjugated systemsdry by cross-linking and the simplest approach is to postulate oxygen attack at the site of theactivated methylene, adjacent to the double bond (C=C), leading to the formation of allylic radicalsobtained by hydrogen abstraction. This gives rise to peroxide formation. In the case of conjugatedsystems, such as tung oil, oxygen addition is directly related to the conjugated system to form 1,4cyclic peroxide.

For non-conjugated oils the mechanism is given by2

R’-CH=CH-CH2-R” - H → R´-CH=CH-�H-R”R’-CH=CH-�H-R” + O2 → R´-CH=CH-CO�H-R”

Once a peroxide, either hydroperoxide or cyclic peroxide, have been formed they dissociate into freeradicals, which enable a series of further reactions to take place. In both cases the peroxidesdecompose by dissociation of the O-O bonds leading to a variety of reaction products includingintermolecular linkage and a cross-linked film is obtained. The polymerisation mechanism for non-conjugated fatty acids is presented below2,3. The reactions are chain reactions which once startedgenerate more and more free radicals and peroxides leading to auto-oxidation6. The overall effect ofthe reactions is that the molecular size of the drying oil molecules is increased.

The termination reaction favours formation of polyperoxides, which subsequently decompose topolyethers. The probability of chain termination is rather high, why the length of the polymerisedchains is relatively short2,3.

Initiation: RH + O2 → R· + ·OOHPropagation: R· + O2 → ROO·

ROO· + RH → ROOH + R·Termination: ROO· + R· → ROOR(Cross-link) ROO· + ROO·→ ROOR + O2

R· + R· → R-R


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During oxidation, a great number of by-products are formed, notably ketones and aldehydes. Theseoxidative by-products are responsible for the odour of oil containing systems, especially thosecontaining drying oils or drying oil derivatives.

The cross-linking takes place more rapidly at the beginning of the drying process; as the complexityof the polymer increases and oxygen penetration of the film is obstructed the process slows down4.But the cross-linking reactions will actually continue very slowly in the dry coating even years afterapplication.

4.3 Driers

The process of oxidative polymerisation in air-drying systems is a rather slow process as it normallytakes from twelve to thirty-six hours to form a tack-free film4 and even for reacted oils such asalkyds the drying is too slow for commercial applications. The drying of air-drying systems istherefore commonly accelarated by the addition of metal driers, or siccatives, which catalyse thedrying reactions. The drying time can then be reduced from days to hours. Driers are generallymetallic soaps containing either alkaline-earth metals or heavy metals combined with monobasiccarboxylic acids. They have the general formula (RCOO)xM where R represent an aliphatic oralicyclic hydrocarbon and M represent a metal with valence x. The acid, which is the anionic part ofthe metallic soap, can be varied8. Naphtenic acid or octanoates, especially the synthetic acids 2-ethylhexanoic acids are usually used today8,11. Napthenates are used more and more rarely, as the have ahigh odour level4. The presence of the acid secures adequate distribution of the metal throughout thecoating medium due to their solubility in organic solvents and binders8.

The drier compound is dissolved or rather mixed into a solvent, which acts as carrier medium.Today dearomatised hydrocarbons are typically used as solvents but drier products with vegetableesters as carrier media have also become available. The fatty acid esters have the advantage, besidesbeing based on renewable resources, that they are able to cross-link with the coating filmminimising the VOC contribution10. Different metal driers possess different drying properties assome metals have much more catalytic effect than other. Round 35 to 40 metals have beenexamined as possible driers, but less than twenty show worthwhile activity1,11.

It has been demonstrated that the metal ion must be able to undergo oxidation with the peroxidespresent in the system before the metal salt can act as a drier. In the case of cobalt the followingmechanism has been proposed2,3,4:

Co2+ + ROOH → Co3+ + RO· + OH ?

Co3+ + ROOH → Co2+ + ROO· + H+

The driers have been shown to take up oxygen as follows:

RH + Co3+ → R· + Co2+ + H+


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R· + O2 + RH → ROOH + R·

Driers have also been shown to act as oxygen carriers to initiate the radical formation:

Co3+ + O2 → Co3+-O-O·

Co3+-O-O· + -CH2-CH=CH-R´ → Co3+-OOH + R-�H-CH=CH-R´ →

Co3+ + ·OOH + R-�H-CH=CH-R´

Based on the activity of the metal the driers are commonly divided into two main classes, namelyprimary (top driers) and secondary driers. Some make a further division of the driers splitting up thesecondary driers into through-driers and auxiliary driers.

Primary driers are also referred to as top driers, surface driers, oxidative driers or catalytic driers.Top driers and primary driers being the most used expressions. They catalyse the formation and/ordecomposition of peroxides, which are formed by the reaction of oxygen with the air-drying binderor drying oil as described in paragraph 2.2. Free radicals are formed and the formation of directpolymer to polymer cross-links (top drying) becomes possible. The reactions do also cause theformation of hydroxyl groups and carbonyl groups on the air-drying oil or binder10.

The hydroxyl groups are then available for the through-driers, which can form oxygen-metal-oxygenbridges (cross-links) between the polymer molecules by means of the hydroxyl groups. Carboxylicacid groups on the binders may also be used by through-driers to make the oxygen-metal-oxygencross-links10.

Air-drying coating usually contain a mixture of different driers to obtain the right balance of top andthrough drying, which is important to obtain the right film properties. The coating manufacturerscan either mix their own drier systems or they can purchase commercial drier packages, containing acombination of several driers in one product.

The action of driers does not stop when the coating is dry. It continues throughout the life of thecoating film thus accelerating the ageing of the organic material. This is shown as a brittleness andbreakdown of the coating film9.

4.3.1 Primary driers (Top driers)Cobalt, manganese, cerium, iron and vanadium are five metals used for commercial top driers,where driers based on cobalt and manganese are the most commonly used. Manganese driers givelonger induction times before the cross-linking starts than cobalt driers do, but have on the otherhand a faster rate of cross-linking once the reactions have started. This suggests that cobalt is a moreeffective catalyst for hydroperoxide formation but that manganese is more effective for the peroxidebreakdown2. Cerium and iron are most effective at elevated temperatures2.


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The main function of primary driers is to promote rapid surface drying of air-drying coatings butthey do also, in varying degree, possess some through-drying properties. Top driers are normallyemployed in coatings in amounts varying from 0.005 to 0.2 % metal based on the solid binder oroil3.

4.3.2 Through-driersThrough-driers are also called cross-linking driers, polymerising driers, coordination driers orsimply secondary driers. There are eight metals used in commercial through-driers: zirconium,lanthanum, neodymium, aluminium, bismuth, strontium, lead and barium10.

Through-driers play no part in the oxidation/reduction cycle as the primary driers do, but onceelectron-donating groups are present they assist in the polymerisation process by the formation ofcoordination compounds with a consequent increase in the drying rate3. Through-driers do onlyfunction in combination with primary driers.

4.3.3 Auxiliary driersAuxiliary driers are also called promoters, coordination driers or secondary driers. Four metals areused for commercial auxiliary driers these are potassium, lithium, calcium and zinc. The first threeusually increase the rate of top drying and zinc usually inhibits top drying10.

Auxiliary driers do not have a catalytic effect on the oxidation process when used on their own, butwhen used in combination with primary driers they act as synergist and increase the rate of oxygenuptake in air-drying systems considerably3.

Auxiliary driers are normally used in amounts varying from 0.05 to 0.5 % metal, based on the solidair-drying binder. Besides promoting the through drying they also improve the stability of the useddrier systems by preventing loss-of-dry of the primary driers1.

4.3.4 Drying acceleratorsDrying accelerators are non-metallic compounds, which are able to increases the activity of the driermetals causing a more rapid drying of the coating film. They function by complexing with the metalatoms in primary driers by forming chelates and are therefore also referred to as chelators10.

Loss-of-dry due to adsorption of the metal drier on the pigment surface is also to some extentreduced by the use of drying accelerators. Furthermore the use of accelerators can reduce theyellowing, which occurs with ageing of the dry coating film, especially in high-solids coatings10.

Two different types of drying accelerators are used extensively commercially. These are 2,2´-bipyridyl and 1,10-phenanthroline. They are both used in solvent-borne as well as water-borne air-drying systems. 2,2´-bipyridyl is most effective in high-solids, drying oils, polyurethane andphenolic modified alkyds, but it is not very efficient in conventional alkyds12.


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4.4 Anti-skinning agents

The presence of driers induces another problem in air-drying coating systems, which is theformation of surface skin on coatings in closed containers. The skin formation is an oxidativepolymerisation of the coating surface, which can take place due to the catalytic effect of the driersand the presence of air pillows between the coating surface and the closed lid. The skinning doesinevitably result in a loss of coating material and a possible contamination of the bulk. Anti-skinning agents are therefore added to air-drying coating to prevent in-can skinning during storage.

Anti-skinning agents react with the free radicals formed during the oxidative polymerisationprocesses, as they are more readily oxidised than the drying oils or drying oil derivatives present inthe coating. The anti-skinning agents do hereby prevent the cross-linking from taking place, why thedrying of the coating is stopped. The agents continue to act until all the anti-skinning molecules areexhausted. As anti-skinning agents prevent the oxidation processes they are also often referred to asanti-oxidants3,4,13,14.

The use of anti-skinning agents is always a compromise between preventing skinning and retainingan adequate drying potential of the coating after application. The cross-linking should be as slow aspossible during storage and then regain its full drying potential as soon as possible after application.The activity of anti-skinning agents should therefore preferably come to an end immediately afterapplication of the coating. The most commonly used type of anti-skinning agents for the preventionof in-can skinning in air-drying coatings is therefore volatile oximes, which due to their highvolatility rapidly become ineffective in open or loosely closed containers. Methyl ethyl ketoxime isfar the most important of the anti-skinning agents, but oximes as butraldoxime and cyclohexanoneoxime are also used from time to time, but they are less efficient4.

Only very small amount of anti-skinning agents are needed to prevent skin formation. Typically is afraction of less than 1% of the total formulation necessary4,13,14.

4.5 Binders for air-drying coating systems

A short description of the different vegetable oils and air-drying binders that are commonly used inair-drying coatings is given in the following paragraphs.

4.5.1 Vegetable oilsVegetable oils have traditionally been used a lot in paints, varnishes and printing inks because oftheir ability to cross-link. The oils are commonly modified before using them in coatings to improvetheir drying properties. The most extensive use of vegetable oils is in the manufacture of alkydresins, ink vehicle systems and other synthetic resins for air-drying coatings3.

4.5.2 Refined oilsRaw vegetable oils produced by expression or solvent extraction contain variable amounts ofimpurities, such as free fatty acids, phospholipids, carbohydrates, sterols etc. For many applications,e.g. alkyd resins manufacture, these impurities are undesirable as they may affect the dryingproperties and pigment wetting capabilities of the oil. The impurities do also tend to precipitate as a


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sludge, when the oil is heated, as it is during varnish and alkyd manufacture, and this affects thecolour, gloss and clarity of the surface coating3,4. Raw oils are therefore rarely, if ever, directly usedin coating formulations4. They are usually refined by treatment with acid or alkali to precipitate theimpurities. As the refined oils also have a relatively slow drying speed they are often modified eitherby direct chemical modification, or by blending or reacting them with synthetic resins3.

4.5.3 Polymerised and oxidised oilsA partly polymerising or oxidising of vegetable oils leads to an increase in the molecular weight.The oil thus has an increased initial molecular weight and fewer cross-links are required to form acoherent film. The drying time of the coating is thereby redused3.

Oils polymerised by heating without the presence of accelerators are called heat-polymerised oils,heat-bodied oils or stand oils. Depending on the oil type the heating might be carried out in thepresence of peroxides to improve the cross-linking. In the case of highly conjugated oils the actionof heat alone is sufficient to bring about a polymerisation. The polymerised oils are available in awide range of viscosities and they are manufactured under controlled conditions of temperature togive pale coloured oils. Heating the oil to round 160-300°C produces polymerised oil. The heatingis continued until the viscosity has increased to the desired value3. Even though the drying speed isincreased, stand oils do still have a rather slow drying speed but their levelling properties isimproved, which is also very important in many surface coating applications2. Stand oils of dryingoils can be used on their own in coatings or they can be used for further processing to for instancealkyd production.

If the oils are heated and oxidised at the same time by blowing air through the oil they are calledblown oils. As the heating temperature is less than that of heat-polymerised oils the process is lessexpensive, but blown oils do not give as durable film as stand oils and they are darker4,5.

Blown oils are manufactured under thermally controlled conditions where the oxidation is broughtabout by heating the oil to about 130°C while air is passing through it. The reaction may becatalysed by the addition of drier metals3,4. The effect of this treatment is to increase the dryingspeed, viscosity, pigment wetting ability, dispersion and flow of the oil.

Boiled oils are produced from linseed oil using one or more driers. They are traditionally processedby the controlled oxidation of raw linseed oils where the metallic driers are used to accelerate thecross-linking. This causes rapid oxidative polymerisation in the air-drying coating, giving filmswhich surface dry within few hours2. The oils are called boiled oils even though the cookingtemperature is below the boiling and decomposition point. By proper control of this reaction boiledoils with a wide range of viscosities can be obtained. The drying time and the colour of the productis dependent on the selection of driers, the quality of the oil and the temperature at which the oil isheated. Boiled oils are usually used in oil paints, enamels and oil-based primers5. Today boiled oilsare often a simple blend of stand oils and driers11.


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4.5.4 Linseed oilLinseed oil is one of the most widely used oils in air-drying coatings. Linseed oil contains a highproportion of unsaturated linoleic and linolenic acids, which give the oil its good air-dryingproperties. Refined linseed oil gives film with excellent durability, good colour and gloss retentionand good pigment wetting properties, but the film has poor acid and alkali resistance and only fairwater resistance3. Linseed oil can be used on its own in coatings, but it is extensively used for theproduction of air-drying alkyd resins and urethanated oils3.

Linseed oil is used for paints, vanishes and printing inks either in the form of polymerised oil orreacted into a synthetic binder as for instance alkyds. Coatings based on linseed oil tend to yellowwith time. This yellowing is mainly caused by the linolenic acid. The higher the content of linolenicacid present in oils the greater the tendency does the dry coating film have to yellow. Coatings basedon linseed oils are therefore mainly used for exterior coatings.

Blown linseed oil has improved drying properties and excellent flow and gloss. It also has a higherwater tolerance and is often added to water sensitive systems. Pigment separation problems mightoccur on extended storage3. Blown oils have a fairly high odour, high acid value and give films witha poor water resistance4. Linseed stand oils are available in a range of viscosities and form film thathave excellent water resistance. They have good gloss and drying properties as well as pale colourand low odour, but their pigment wetting abilities is fairly poor3. Linseed stand oil is similar inproperties to blown oil but has better drying, colour retention and durability. In addition, it has goodlevelling properties and has far less tendency towards pigment separation3.

4.5.5 Tung oilAround 80 % of the fatty acid content of tung oil is conjugated eleostearic acid, which gives tung oilits rapid air-drying properties. The surface drying of tung oil is actually so rapid that it often drieswith a wrinkled surface and even in very thin films there is a tendency for the oil to have a frostyappearance. The tendency to wrinkle can be partly overcome by “gas checking”, which is a thermalpolymerisation of tung oil4.

Tung oil is rarely used on its own because of is rapid drying to a tough, glossy film, but it is usedextensively in oil based printing inks often in combination with hard resins as phenolic resins, rosinesters or alkyds. Coatings containing tung oil have excellent chemical and water resistanceproperties. Tung oil generates a high level of odour as it dries and its rather dark colour issometimes a problem3.

4.5.6 Soya bean oil and sunflower oilThese oils are very similar in fatty acid composition and are often used interchangeably. They aresemi-drying oils, which are mainly used in their refined form and especially for alkyd manufacture3.They have a pale colour, making them suitable for use in white coating systems and varnishes. Bothoils have excellent pigment wetting abilities, especially with carbon blacks4. Both have excellentcolour retention properties and film flexibility.


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4.5.7 Safflower oilThis oil contains a higher proportion of conjugated fatty acids than both soya or sunflower oils andhence has better drying characteristics although still classified as semi-drying oil. Safflower ismainly used in its refined form and it is used in place of soya or sunflower oils where better dryingis needed. Safflower oil does like sunflower and soya bean oil provide non-yellowing alkyds.

4.5.8 Tall oilTall oil is not a “true” vegetable oil as it is obtained as a by-product from wood pulp production, butas it contains unsaturated fatty acids it is able to air-dry like vegetable oils. Tall oils are used for theproduction of alkyds.

4.6 Alkyd binders and their uses

Alkyd is one of the most used binder type within the European paint industry accounting forapproximately 25 % of the total amount of consumed binders and at present they hold a majorityshare of the world market for non-aqueous binders3,7.

Alkyd resins are short branched polyester chains containing fatty acids. They are condensationproducts of polyols, polybasic acids and vegetable oils or fatty acids. The polyols most commonly usedare glycerol and pentaerythritol. The polybasic acid is usually phthalic anhydride, but it can also beisophthalic acids or trimellitic anhydride. Aliphatic polybasic acids are also used from time to time.Air-drying water-borne alkyds can be produced by using trifunctional carboxylic acid anhydrides.

The presence of the oil provides alkyd binders with good pigment wetting properties and when theoil is unsaturated good air-drying properties are provided as well. The polyester chain giveshardness and durability to the film and improved drying speed3. Oils most widely used for theproduction of air-drying alkyds are linseed oil, soya oil, tall oil, tung oil, and safflower oil. Dehydratedcastor oil, linoleic acid and linolenic acid are also used in the production of alkyds4.

The properties and nature of the final alkyd is dependant on the quantity, type and nature of themodifying oil, fatty acid or acid anhydride used as well as the processing conditions. Alkyds areclassified as drying, semi-drying or non-drying dependent on the oil type used for manufacturing thealkyd and they are furthermore classified according to their oil content. Alkyds may be furthermodified by reacting urethane, styrene, vinyl toluene or silicone groups into the alkyd binder toprovide specific properties.

Alkyds containing more than 55 % w/w of oils are called long oil alkyds. Alkyds with oil contentranging from 45-55 % w/w are classified as medium oil alkyds whereas short oil alkyds contain lessthan 45 % w/w of vegetable oil 3,4,5. Short oil types dry fast by solvent evaporation but show limitedcross-linking. Long oil alkyds dry slower, but their final durability is much better due to better cross-linking2. Air-drying alkyds contain drying or semi-drying oils or fatty acids, and are able to formfilm by oxidative cross- linking. This type of alkyd usually has an oil length greater than 45%3.

The molecular weight of an alkyd is considerably higher than that of a vegetable oil, which meansthat fewer cross-links are required before a coherent film is formed. Alkyd binders do therefore dry


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much more rapidly than the corresponding vegetable oils, but they do though still need the additionof driers to obtain a drying time which is acceptable for commercial coating systems. The use ofdriers allow the alkyd resin formulator to employ semi-drying oils such as soya bean, tall oil andsunflower oil in an alkyd and yet have rapid drying capability3. Semi-drying oils have a lesstendency to discolour on drying, due to a smaller content of linolenic acid, than the drying oils. Thusby accepting a small decrease in drying efficiency, a considerable colour improvement can beobtained.

Alkyds are very versatile in use and can be used in several coating types such as paints, enamels,stains, varnishes, lacquers and printing inks. They can be utilised in a variety of applications both indecorative, industrial and speciality coatings. Oil inks are formulated almost exclusively from longoil alkyds3. Because of their compatibility with other resins and possible variations in formulation,alkyd coatings with a wide range of properties are obtainable.

4.6.1 High solids paintsAlkyd binders for high solids paints are similar to those for conventional organic solvent-bornesystems but they have a lower molecular weight. This makes it possible to formulate systemscontaining less volatile organic solvents and yet having appropriate viscosity. Solvent free highsolids systems can be formulated by using reactive diluents.

4.6.2 Waterborne systemsAlkyd binders for waterborne systems are made either by converting the resin into an emulsion withthe use of emulsifiers or by incorporating water-soluble and cross-linking groups in the binder; e.g.carboxyl groups neutralised with ammonia or reactive amines2.

4.6.3 Modified Alkyd ResinsAlkyds can be modified to have properties ranging from fast drying hard coatings to slow drying,soft and flexible films3. The properties of alkyds are relatively easy tailored to specific needs, asthere are several parameters available for adjustments (chain length of fatty acids, degree ofunsaturation, number of free OH groups, branching etc.). Modified alkyds are made by graftingvinyl monomers (styrene, methacrylates etc.) by radical mechanism onto unsaturated sites of theresin or be reacting free hydroxyl groups with silicone and isocyanates. Modified alkyds are widelyused in applications where higher weatherability and durability, faster drying and higher gloss aredesired than in conventional alkyd coatings7. The most commercially important alkyd modifiedresins are described in the following paragraphs.

4.6.4 Urethane alkyds and urethane oilBoth alkyds and vegetable oils can be modified by reaction with isocyanate containing compounds.The film formation in these modified compounds occurs due to the presence of unsaturatedvegetable oils as is the case with conventional alkyds, but the higher molecular weight of theurethane alkyd and urethane oils gives increased drying speed3.

Oil-modified urethanes are similar to conventional alkyds in drying and use, but they producecoatings that are harder and more resistant. Compared to alkyds, they offer shorter drying time,


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better water resistance, better gloss development and retention, greater ease of dispersion and easieradjustment of viscosity. Oil-modified urethanes have excellent durability as clear coatings. Whenpigmented they have to be blended with alkyds to obtain outdoor durability.

Urethane alkyds have better all round performance properties than urethane oils3. Urethane alkydsare designed for use in clear or pigmented systems as a one-pack urethane coating finish. It may beused on its own or in blends with other drying alkyds. It provides films, which have an excellenthardness, adhesion and gloss. A better drying is obtained as well as improved chemical andmechanical resistance3. Films formed from alkyds containing high levels of urethane modificationshow an increased tendency to yellow due to the aromatic isocyanate compound used.

Urethane alkyds are often used in marine varnishes and for metal primers and topcoats. They arealso used in blends with unmodified alkyds in air-drying decorative paints to improve the drying.The use of urethane alkyds and oils are however limited to some extent as they can produce thermaldecomposition products such as toluene di-isocyanate, which represent health and safety problems3.

4.7 Prospect for the use of air-drying coatings

Western Europe produces about 5 million tonnes of coatings per year, which accounts forapproximately 22 % of the world production. The coating systems accounting for the largestconsumption of vegetable oils are alkyd coatings, which are widely used for both industrial anddecorative purposes. Despite a considerable loss of market shares during the last decades alkyds arestill the most used binders in Europe. In 1996 the European coating industry consumed 1.8 milliontonnes of binders of which 25 % were alkyds7.

One of the parameters, which largely influence on the use of air-drying coatings, is the need toreduce solvents, or volatile organic compounds (VOC), due to environmental concerns. To reducethe amount of VOC there is a strong trend towards using water-borne coatings and high solids paints.This has meant a decline in the consumption of conventional solvent-based alkyd coatings. The needfor VOC reduction has furthermore introduced the use of chemically modified oils as reactivediluents in certain types of coating systems, especially high solids paints. A reactive diluent is aproduct that combines the solvent properties of diluting the paint to the right viscosity, with the binderproperties of reactive with air to a protective coating film.

The possibility for substituting volatile solvents with reactive diluents has improved with time as agrowing number of reactive diluents have become commercially available, but systems containingreactive diluents do suffer from having a relatively long drying time compared to waterbornesystems as well as conventional air-drying systems. The relatively slow drying process is though abasic drawback for air-drying coatings in general, which necessitate the addition of driers to speedup the drying process.

The presence of heavy metal based driers is undesirable from an environmental and health view.This especially accounts for the cobalt containing driers, which are the most commonly used drierstoday. This could mean an even stronger environmental pressure on air-drying coatings in thefuture, but as the development of driers is heading towards the use of less toxic metal compounds assubstitutes for cobalt driers this might not become a major problem.


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Besides VOC-reduction, environmental concerns have furthermore resulted in an increased interestin products based on renewable resources. As air-drying coatings contain a relatively large amountof vegetable oils it might become a driver for an increased use of such systems. Especially in themore environment friendly forms as high solids paints or waterborne coating and in the Nordiccountries traditional linseed oil paints have in fact regained some popularity. The market for linseed oilpaint is though still very limited.

The major reason why alkyd binders still are the most used binders, despite environmental pressure,is partly due to their cost-effectiveness and partly due to a continuous development of new typesalkyd binder. Conventional air-drying alkyds are relatively inexpensive in terms of raw materialsand manufacturing costs and since they are also readily soluble in the less expensive organicsolvents, they provide the surface coating formulator with a relatively low cost binder. At the sametime alkyd coatings are relatively easy to handle and they possess sufficient film properties for manyapplications. Conventional air-drying alkyds are therefore still used to a large extent for industrialapplications.

Coatings used for protection of exterior wood surfaces are still for the major part solvent-based air-drying systems, but because of the environmental issues it is desirable to introduce low VOCproducts in this application area. The more environment friendly products that will becomeavailable in time will most likely be based on air-drying binders, such as alkyds for water-bornesystems or modified alkyds, as for instance alkyd-acrylic hybrids (blended or polymerised). Anotherpossibility is to use high solids alkyds together with reactive diluents as in this project.

The use of air-drying coatings for indoor purposes is for the time being limited by the fact that alkydcoatings show a strong tendency to yellow. Conventional solvent-borne coatings will continue to beunder pressure due to the need for solvent reduction, why a further decline in the use of alkydbinders for solvent-borne air-drying systems might be experienced. On the other hand alkyds may beable to hold its total market shares because of increased availability for waterborne systems and forhigh solids paints, combined with the possibility of using reactive diluents. Furthermore, a multitudeof different modified alkyd binders has become available, which can be used for specific industrialcoating systems. This will probably also counteract the decline in conventional alkyd binders tosome extent. If the objectives of this project to develop vegetable oils with better drying propertiesas well as a less tendency to yellow, can be accomplished the perspective for air-drying coatingswill improve even further.

5 Choice of raw materials

During the project the Swedish Farmers Association has produced and delivered Purolin®, which isa linseed oil with a changed fatty acid composition (rich in linoleic acid instead of linolenic acid),and Linutin®, which is a low viscous linseed methyl ester. Purolin was obtained from linseed grown1999 and 2003 on Gotland. The cold-pressed oil was refined at The Swedish Farmers Associationin Odensbacken, Örebro, by addition of bleach earth followed by filtration. This procedure removesthe polar impurities and yields a pale yellow oil with a slight fresh smell.


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It was decided at an early stage that Solutia should produce the following raw materials based onPurolin: Boiled oil, stand oil, and two alkyd products, one in white spirits and one in Linutin, with aoil length of 65 %. Furthermore, a short oil alkyd based on Purolin was also made. Finally, aurethane-modified alkyd based on Purolin/linseed oil was part of the project plan. The boiled oilshould contain a standard drier system containing Co and Zr.

The choices of reference products were: An acid-refined linseed oil used by Solutia, two stand oilsused by Uulatuote Oy and 1 boiled oil delivered by Fredlunds.

5.1 Laboratory scale production of raw materials

Stand oil, boiled oil and alkyds based on Purolin have been produced on a laboratory scale atSolutia. The alkyds produced are compared to a commercial alkyd based on refined linseed oil. Thealkyd products based on Purolin have a binder content of 60 % in white spirit and Linutin,respectively.

5.2 Methods for characterization of raw materials

5.2.1 Rheology measurements on raw materials and reference materialsThe raw materials were characterised by viscosity measured on a rotational viscometer with definedshear rate (ISO 3219-93): “Determination of the rheological behaviour of paint and printing inksusing a rotational viscometer with defined shear rate”. A Bohlin VOR Rheometer with standardgeometry and different torque bars was used for the measurements. The viscosity was measuredover a large range of shear rates, but as all the investigated materials are Newtonian (same viscosityat all shear rates) or shows slightly shear thinning behaviour the viscosity is given as a single valueat 146 s-1 for each sample.

An oscillation method was used to evaluate the elasticity of each material, where a frequency isinduced in the sample instead of a rotational movement (shear rate). The elasticity of a material isdefined by the phase angle Delta. The values for the phase angle can be between 0 and 90. If thephase angle is 0, the material will act as a rubber band, and if the phase angle is 90 the material willact as a solid. The phase angle is given as an average value obtained from measurements over arange of different frequencies.

5.2.2 Preparation and application of drying oils and alkydsA standard drier composition containing Co (0,05 %), Zr (0,06%) and Ca (0,11%) calculated on theoxidative drying matter was used for the stand oils as well as the alkyds. This composition iscommonly used by Solutia. After including the drier system the alkyds were thinned with whitespirits to 50 % dry matter. The same drier composition was used in samples with 100 % dry matter.All samples were dispersed slowly for 10 minutes. The samples were left to rest for at least 16 hoursbefore measuring the drying properties.

The samples were applied on glass plates with different film thickness depending on the dry matter.The dry film thickness has been controlled with a mechanical device.


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5.2.3 Drying timeThe drying time of each raw material has been evaluated both manually and with a drying timerecorder used in accordance with ASTM D 5895 – 96 “Measuring Times of Drying or Curingduring Film Formation of Organic Coatings Using Mechanical Recorders”.

Drying time measurements using a straight line drying time recorder are performed in the followingway. The samples are applied on glass plates in a well-defined film thickness. The stylus of thedrying time recorder is immediately after application lowered down into the wet film. The stylusthen moves across the sample on the glass plate with a constant and well- defined velocity. Themeasurements are performed at 23 ± 2°C and at a relative humidity of 50 ± 5%.

Afterward the track left of the stylus on the film is evaluated. The drying of the film is divided intofollowing stages:

Stage 1: Set-to-touch timeThe set-to-touch condition is reached when the film has solidified sufficiently in such a manner thatit no longer flows or sticks to objects that lightly touch it. In this test method it means when a pear-shaped depression appears in the film, and when the film stops flowing over the path of the recorderstylus, which then leaves a continuous track in the film.

Stage 2: Tack-free timeThe tack-free condition is reached when the film surface has dried to an extent where the film nolonger adheres to light objects placed on it. In this test method it means when the continuous trackof the stylus in the film stops and the stylus starts to tear the film or leave discontinuous cutting ofthe film.

Stage 3: Dry-hard timeThe dry-hard condition is reached when the drying have proceeded to an extent where the film is notdisplaced or that no noticeable marks are left on the film when influenced with a relatively strongpressure. In this test method it means that the stylus stops tearing or cutting the film, but leaves avisible trace on the film.

Stage 4: Dry-through timeThe dry-through condition is reached when the film has solidified so completely that a largetwisting force can be applied without distorting the film. In this test method it means that the stylusno longer leaves any visible tracks on the film.

5.2.4 Hardness of dry film (Pendulum hardness)The pendulum hardness was measured according to ISO 1522-73 “Pendulum damping test” afterdifferent periods of drying time after application of the sample on a glass plate. The wet filmthickness was 60 microns for materials that have 100 % of dry matter and 120 microns for materialswith 50 % of dry matter. The samples were stored at 23 ± 2°C and at a relative humidity of 50 ± 5%during a drying period of 28 days.


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The hardness of the samples is determined by registering the time (number of pendulum swings) ittakes before the amplitude of the pendulum is damped to a certain extent. The more swingsobserved the harder the film is.

5.3 Characterization of raw materials

The different oils were analysed by the Svalöf Laboratory (Svenska Lantmännen). In the followingtables the fatty acid composition and some basic data given for the oils.

Table 4.1 The fatty acid composition of the oilsSample Description C16:0 C16:1 C18:0 C18:1 C18:2 ”misc.” C18:3 ”misc.” >C20

Boiled linseed oil from Fredlund 5,4 3,3 17,4 14,8 57,7 1,4

Standoil Purolin made by Solutia 8,4 0,1 4,9 17,4 59,2 1,0 4,3 4,7

Boiled linseed oil from Uula 5,8 0,1 3,3 18,8 14,4 55,2 2,4

Standoil P200 from Uula 10,3 0,3 6,0 31,7 8,5 12,2 5,1 11,3 14,6

Linseed oil Solutia Solutia quality 5,0 3,3 19,3 14,6 55,2 2,6

Boiled Purolin Boiled atSolutia

5,8 0,1 3,4 13,5 68,2 7,6 1,4

Boiled Linseed oilSolutia

Solutia quality 5,4 3,5 20,2 14,8 53,8 2,3

Purolin SLR quality 5,7 3,4 13,2 74,4 2,7 0,6

Table 4.2 Some basic data for the oilsSample Description Acid no. Peroxide

no.Phosphor/

ppmBoiled linseed oil from Fredlund 2,4 30 160

Standoil Purolin made by Solutia 1,2 11

Boiled linseed oil from Uula 2,6 83 290

Standoil P90 from Uula 6,8 10 5

Standoil P200 from Uula 7,6 8

Linseed oil Solutia Solutia quality 0,4 22 5

Boiled Purolin Boiled atSolutia

1,6 88

Boiled Linseed oil Solutia Solutia quality 1,4 60

Purolin SLR99 1 ca 10 1

5.3.1 Rheology measurements on raw materials and reference materials

The viscosity of the different samples is of course directly related to molecule size and shape.Linutin has the lowest viscosity and the alkyds the highest viscosity. It can also be seen that alkydsdiluted with white spirit have a lower viscosity than the same alkyd diluted with Linutin. None ofthe samples shows an elastic behaviour.


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Table 4.3. Description and rheology of raw material samples at 23°C.

Sample Description Torque element(gcm)

Viscosity shear rate146 s-1 (mPas)

OscillationPhase angle

VOCFRILIN A 8808 Standoil Purolin. Produced at 175°C with di-tert.Butylperoxide.

88.50 3870 88

VOCFRILIN A 8813 SAL 650h/60WS – Alkyd produced on Purolin and WhiteSpirit.

88.50 2555 86

VOCFRILIN A 8818 SAL 650h/60linutin – Alkyd produced on Purolin andLinutin.

88.50 4175 84

VOCFRILIN A 8819 SAL 650h/60WS – Alkyd produced on Linseed Oil andWhite Spirit. Std. product

88.50 2447 87

VOCFRILIN A 8839 Short oil alkyd produced on Purolin and Linutin 88.50 1530 89

VOCFRILIN A 8844 Urethane alkyd produced on Purolin 88.50 2710 86

Urethane alkyd TO 167 Standard urethane alkyd in White Spirit 88.50 1350 88

Stand oil P. 90 Stand oil – viscosity 90 Poise: Reference - Uulatuote Oy 88.50 5880 88

Stand oil P. 200 Stand oil – viscosity 200 Poise: Reference – Uulatuote Oy 88.50 17000 86

Linseed oil Solutia Linseed oil. Reference - Solutia quality 3.73 43 80

Boiled Linseed oil Boiled Linseed Oil. Reference - Solutia quality 1.31 49 88

Purolin Purolin 3.73 49 85

Boiled Purolin Boiled Purolin 1.31 57 87

Linutin Linutin 1.31 6 77

5.3.2 Drying timeThe drying time measured with a drying time recorder has been evaluated. It should be noted thatevaluating clear lacquers is quite difficult and that is the reason for the question marks seen in table4.4. It should be noted that the drying time is shortest for the short oil alkyd and the urethan alkyd.

Table 4.4. Drying time measured with a drying time recorder.

Sample Film thickness Velocity Drying time, wet(hours)

Drying time, dry (hours) Comments

wet dry wet (0 ->) half wet surface dry dry through

my my cm/h Stage 1 Stage 2. 2 Stage 3 Stage 4.

VOCFRILIN A 8808 40 15 3 1 2 >20 traces 2-20 h80 37 1.2 1.1 1.7 2.5 >50 cut op 9,.5-50 h

VOCFRILIN A 8813, 50% 40 5 3 0,5 0,9 10 traces 0.9-10 h

VOCFRILIN A 8818 80 35 1.2 1.3 3.4 4.8 >50 traces 6.9-50 hVOCFRILIN A 8819 100 - 1.2 0.6 1.3 >50 >50 Traces >50VOCFRILIN A 8835 100 - 1.2 1.5 1.9 >50 >50 Traces >50VOCFRILIN A 8839 60 - 1.2 7.1 - 10 10.8 TracesVOCFRILIN A 8844 100 - 1.2 0.8 2.1 17.5 17.5 No tracesUrethane TO 167 st 100 - 1.2 1.1 2.1 11.7 20 No traces

Stand oil P. 90 40 15 3 1.5 2.2 8.3 >20 traces 8.3-20 h80 45 1.2 2.5 4 >50 cut up 4-50 h

Stand oil P. 200 40 14 3 1.2 1.7 12 >20 traces 12-20 h80 40 1.2 2 3.7 >50 cut up 3.7-50 h

Boiled Purolin 40 1.2 the oil shrinksLinseed oil boiled, hot oil 40 22 1.2 10.8 11.4 11.9 traces 11.4-11.9 hBoiled Linseed oil Solutia 40 22 1.2 3.8 5.6 6.5 (32?) traces 6.5-32 h ?


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5.3.3 Hardness of dry filmThe hardness of dry the different binders after adding standard driers has been measure. The boiledoil gives a very soft film. Stand oils are would show a similar pattern and thus the data is notincluded here. It is also obvious that the alkyds where Linutin is used as a thinner gives a muchsofter film. The reason is of course that these alkyds in this way have 100 % dry matter and theLinutin will then act as a softening agent. Comparing the same alkyd made on linseed oil comparedto Purolin shows that the Purolin alkyd (without Linutin) is softer than the Linseed oil alkyd. It isthough interesting to see that the Urethanalkyd becomes much harder if it is pproduced on Purolin.The hardness data can also be seen in figure 4.1.

Table 4.5. Pendulum hardness: Damping time (seconds) observed after different periods of drying time.

Drying time(hours)

A8813 A8818 A8819 A8835 A8839 A8844 TO 167 Purolin kogt

147 17 23 23 27 14 46 38 22

316 20 19 37 49 13 59 40 18

483 29 18 50 68 13 77 46 17

672 33 18 54 74 14 85 50 16

816 36 16 62 81 13 91 52 15

1104 37 18 57 76 14 87 50 15

1320 38 17 63 83 13 90 50 16

Figure 4.1. Development of hardness

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400

Drying time (hours)

Dam

pin

g ti

me

in s

econ

ds A8813

A8818

A8835

A8839

A8844

Purolin kogt

TO 167

AL 650h


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5.3.4 YellowingIn order to investigate how the change fatty acid pattern affect the colour change of the treatedwood, panels (pine) were treated with small amount of oil and stored in day light for 3 months. Thepanels treated with traditional linseed oil showed a clear yellowing after this time, whilst the panelstreated with Purolin kept their original colour (Figure 4.2). The results can be explained by theabsence of linolenic acid in Purolin. This fatty acid is easily rearranged to a coloured conjucatedacid in the presence of oxygen.

Fig 4.2: Comparison of wood panels treated with Purolin and Linseed oil (ca 300g/m2). The panelswere stored in a room at normal temperature and light.

5.4 Summary and conclusions

The results showed that the stand oil based on Purolin dried quickly on the surface and has a quitehigh hardness to start with. This indicates that this oil should have another drier system. The Purolinbased stand oil does furthermore dry faster than the 2 commercial stand oils and the surfacehardness is higher even though the viscosity of the Purolin stand oil is lower.

As expected, the alkyds dry faster than the other samples and develop the highest hardness. Thealkyd based on Purolin diluted in Linutin gives a very soft film. Using Purolin instead of linseed oilwhen producing the urethane alkyd gives a harder film than expected.

6 Model formulations for floor oils

The model formulations for floor oils were chosen in cooperation by EnPro, Engwall o Claesson,University in Umeå and Svenska Lantmännen. In Table 1 the oil composition of each sample isdescribed. The samples G1-7 were selected in a multivariate designed experimental set-up.Furthermore, a number of references were chosen (>G7). The naming of the sample also indicatesthe drier system, but this is described in the next chapter.


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Table 5.1. Model floor oils and references.

Sample Formulation weight-%G1c: Purolin 100G2c: Purolin

Linutin8020

G3c: PurolinLinutin

6040

G4c: Linseed oil Solutia 100G5c: Linseed oil Solutia

Linutin8020

G6c: Linseed oil SolutiaLinutin

6040

G7c: PurolinLinseed oil Solutia

Linutin

404020

G8c: Boiled linseed oil Solutia 100G9c: Standoil from Uulatohte 100

G10g: Purolin 100G11g: Linseed oil Solutia 100G13c Standoil from Uulatohte

Linutin6040

6.1 Choice of drier system

The work to choose the correct drier system started with a recipe used by Solutia. Several drierrecipes, using different concentrations and metals, were tested with linseed oil and Purolin. The testincluded Cobalt, Manganese, Zirconium and Calcium. The assessment was based on drying timeand hardness of dry film.

The drying times were measured with a drying time recorder and evaluated. It should be noted thatevaluating clear lacquers is quite difficult. Some of the results were therefore somewhat inaccurate.

The best results were obtained with a drier combination of Co 0,24 %, Zr 0,34 % and Ca 0,40 %.The drying test showed that Linseed oil dries faster than the oils based on Purolin. Several of thesamples develop a good surface. Compared with the result of the drying time for samples based onLinseed oil and Purolin, a drier system with 0,24 % Cobalt, 0,34 % Zirconium and 0,40 % Calciumwas chosen. Also a drier system with Mn 2,0%, Zr 0,5% and Ca 0,4% was chosen for furthertesting. A drying time of about 24 hours was considered reasonable.

All the results from the hardness test were similar. They started at a relative high level, but with asmall difference in the values and ends up soft. The results have not contributed to the final choiceof good drier systems.


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6.2 Rheology

The rheology of the model systems was measured. The measured results shows differing viscosities,but the Phase angles are similar. As expected the stand oil samples have a higher viscosity than theother oils. A low phase angle would indicate an elastic oil.

Table 5.2. Description and rheology of floor oils samples at 23°C.

Sample Description Torque element(gcm)

Viscosity(mPas)

Phase angle

G1c Purolin added Cobalt, Zirconium and Calcium 1,31 69 79

G2c Purolin and Linutin (4:1) added Cobalt,Zirconium and Calcium

1,31 40 77

G3c Purolin and Linutin (1,5:1) added Cobalt,Zirconium and Calcium

1,31 27 69

G4c Solutia linseed oil added Cobalt, Zirconium andCalcium

1,31 59 77

G5c Solutia linseed oil and Linutin (4:1) addedCobalt, Zirconium and Calcium

1,31 41 74

G6c Solutia linseed oil and Linutin (1,5:1) addedCobalt, Zirconium and Calcium

1,31 25 74

G7c Purolin, Solutia linseed oil and Linutin (2:2:1)added Cobalt, Zirconium and Calcium

1,31 41 82

G8c Boild Solutia linseed oil added Cobalt,Zirconium and Calcium

1,31 69 81

G9c Stand oil P 90 added Cobalt, Zirconium andCalcium and anti-skin agent Exkin 518

24,85 6200 87

G10g Purolin added Manganese, Zirconium andCalcium

1,31 467 84

G11g Solutia linseed oil added Manganese,Zirconium and Calcium

1,31 289 85

G13c Stand oil P 90 and Linutin (1,5:1) addedCobalt, Zirconium and Calcium

3,73 300 76

6.3 Drying time of prepared samples

The drying time of each floor oil has been evaluated both manually and with a drying time recorderused in accordance with ASTM D 5895 – 96 “Measuring Times of Drying or Curing during FilmFormation of Organic Coatings Using Mechanical Recorders”.

In table 10 the drying times measured with a drying time recorder are evaluated. It should be notedthat evaluating clear lacquers is quite difficult. Most of the oils have a good surface, but some ofthem have a tendency to make an uneven surface. The drying time is between 16 and 38 hours.


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Table 5.3. Drying time (hrs) measured with a drying time recorder.

SampleFilm thickness Velocity Drying time, wet

(hours)Drying time, dry (hours) Comments

Wet dry wet (0 ->) half wet surface dry Dry through

My my cm/h Stage 1 Stage 2 Stage 3 Stage 4

G1c 30 1,2 2,2 7,9 8,7 30,5 Good surfaceG2c 30 1,2 1,8 10,6 11,8 32,6 Pretty good surface,

but weak unevenG3c 30 1,2 1,5 4,3 7,3 38,3 Little uneven surfaceG4c 30 1,2 2,9 4,2 4,5 16,25 Very good surfaceG5c 30 1,2 4,2 6,4 8,3 18,3 Very good surfaceG6c 30 1,2 6,0 10,5 15,5 24,8 Good surface, weak

drying tendencyG7c 30 1,2 5,5 8,6 10,0 17,7 Very good surfaceG8c 30 1,2 3,3 4,9 5,9 22,9 Good, little uneven

surfaceG10g 30 1,2 1,3 4,6 6,3 27,3 Little uneven surfaceG11g 30 1,2 3,3 7,4 8,8 31,6 Little uneven surface

6.4 Oil penetration of wood panels

The penetration of wood panels was tested. The wood panels we weighed before applying thesample, after application of sample and again after 8 hours were the excess oil was wiped off beforeweighing. The test was carried out on both pine and oak panels. The result are shown in table 5.4.

Table 5.4 Oil penetration of wood. Amount absorbed after 8 hours.Sample Description Type of

woodAmount of oil entry

[gram/m²]

G1c Purolin added Co, Zr and Ca Pine 137,9G2c Purolin and Linutin (4:1) added Co, Zr and Ca Pine 153,6G3c Purolin and Linutin (1,5:1) added Co, Zr and Ca Pine 115,8G4c Solutia linseed oil added Co, Zr and Ca Pine 97,9 *G5c Solutia linseed oil and Linutin (4:1) added Co, Zr and Ca Pine 92,4G6c Solutia linseed oil and Linutin (1,5:1) added Co, Zr and Ca Pine 96,0G7c Purolin, Solutia linseed oil and Linutin (2:2:1) added Co, Zr and Ca Pine 96,3G8c Boild Solutia linseed oil added Co, Zr and Ca Pine 133,0 *G9c Stand oil P 90 added Co, Zr and Ca and anti-skin agent Exkin 518 Pine 103,3 *

G10g Purolin added Mn, Zr and Ca Pine 100,5 *G11g Solutia linseed oil added Mn, Zr and Ca Pine 93,7

G1c Purolin added Co, Zr and Ca Oak 144,7G2c Purolin and Linutin (4:1) added Co, Zr and Ca Oak 161,9G3c Purolin and Linutin (1,5:1) added Co, Zr and Ca Oak 99,0G4c Solutia linseed oil added Co, Zr and Ca Oak 108,4 *G5c Solutia linseed oil and Linutin (4:1) added Co, Zr and Ca Oak 98,1G6c Solutia linseed oil and Linutin (1,5:1) added Co, Zr and Ca Oak 117,1G7c Purolin, Solutia linseed oil and Linutin (2:2:1) added Co, Zr and Ca Oak 116,5G8c Boild Solutia linseed oil added Co, Zr and Ca Oak 108,3 *G9c Stand oil P 90 added Co, Zr and Ca and anti-skin agent Exkin 518 Oak 101,5 *

G10g Purolin added Mn, Zr and Ca Oak 116,9 *G11g Solutia linseed oil added Mn, Zr and Ca Oak 82,9


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The mark * means that the oil was difficult to remove after 8 hours. The result should be a littlelower in these cases.

6.5 Surface tension

The surface tension of the samples was measured, in accordance with ISO 304-85 “Surface activeagents – Determination of surface tension by drawing up liquid films.”

The measurement is made three times for each sample and then the corrected surface tension iscalculated after a formula in an ASTM standard: “ASTM D 971-91 – Standard Test Method forInterfacial Tension of Oil Against Water by the Ring Method. The results in table 5.5 are of thesame order.

Table 5.5. Description, density and surface tenson of floor oils samples at 23°C.

Sample Description Density[g/cm³]

Measured surfacetension[mN/m]

Corrected surfacetension [mN/m]

G1c Purolin added Cobalt, Zirconium and Calcium 0,9180 33,5 32,4

G2c Purolin and Linutin (4:1) added Cobalt,Zirconium and Calcium

0,9112 33,5 32,4

G3c Purolin and Linutin (1,5:1) added Cobalt,Zirconium and Calcium

0,9043 33,3 32,2

G4c Solutia linseed oil added Cobalt, Zirconium andCalcium

0,9226 34,8 33,7

G5c Solutia linseed oil and Linutin (4:1) addedCobalt, Zirconium and Calcium

0,9148 33,9 32,8

G6c Solutia linseed oil and Linutin (1,5:1) addedCobalt, Zirconium and Calcium

0,9071 33,1 32,0

G7c Purolin, Solutia linseed oil and Linutin (2:2:1)added Cobalt, Zirconium and Calcium

0,9130 33,2 32,1

G8c Boild Solutia linseed oil added Cobalt,Zirconium and Calcium

0,9226 34,1 33,0

G10g Purolin added Manganese, Zirconium andCalcium

0,9180 34,0 32,9

G11g Solutia linseed oil added Manganese,Zirconium and Calcium

0,9226 34,2 33,1

6.6 Water Pickup of floor oils

Water Pickup of the samples was tested to investigate the hydrohobicity of the model floor oils. Thestandard used is ASTM D 4942-89 “Water Pickup of Lithographic Printing Inks and Vehicles in aLaboratory Mixer.

The method is to put 50 ml sample and 50 ml water in a Mixer cup and then mix for 5 minutes.Some of the water will then be picked up in the oil system. Then the mixture is decanted to agraduated glass and after a while the mixture will split up in 2 phases, and the amount of waterincorporated in the oil phase can calculated. The results water pickup in % is shown in table 5.6.


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Table 5.6. Water pick-up of oil samplesSample Description Amount of Water Pickup

[%]

G1c Purolin added Co, Zr and Ca 14G2c Purolin and Linutin (4:1) added Co, Zr and Ca 10G3c Purolin and Linutin (1,5:1) added Co, Zr and Ca 30G4c Solutia linseed oil added Co, Zr and Ca 90G5c Solutia linseed oil and Linutin (4:1) added Co, Zr and Ca 18G6c Solutia linseed oil and Linutin (1,5:1) added Co, Zr and

Ca9

G7c Purolin, Solutia linseed oil and Linutin (2:2:1) added Co,Zr and Ca

20

G8c Boild Solutia linseed oil added Co, Zr and Ca 99G9c Stand oil P 90 added Co, Zr and Ca and anti-skin agent

Exkin 5189

G10g Purolin added Mn, Zr and Ca 40G11g Solutia linseed oil added Mn, Zr and Ca 25

The amount of Water Pickup in the oils, can give an indication of how hydrophobic/hydrophilic theoil systems are. Water resistance has not been measured but could be a complement to this test.


There appears to be clear differences between the oils. The results of oil penetration of wood showssurprisingly that the viscosity of the oil is not related to the ability to penetrate wood. If the oil isdiluted with Linutin the penetration is not improved. There appears to be a difference between theoils based on Purolin and traditional linseed, in that Purolin based products has a higher penetrationin wood. There is also an indication that Purolin-based oils have a lower water uptake.

7 Analysis of drying mechanisms

7.1 Comparison between linseed oils rich in linoleic acid vs linseed oils rich in linolenic acid

The present work shows that large difference in the curing performance of linseed oil coatings canbe obtained by changing the fatty acid pattern in the oils. Traditional linseed oil, rich in linolenicacid, dries rapidly but the coating suffers from high degrees of residual unsaturation in the curedfilm. This is detrimental for the long-term durability and colourfastness. Too rapid drying will alsoresult in poor through cure due the formation of a skin layer acting as a diffusion barrier to oxygen.A linseed oil variety rich in linoleic acid is shown to exhibit a very different behaviour. This oil willproduce slightly softer films but with a significantly lower amount of residual unsaturation, noproblem with skin formation, and good through cure. This will result in a coating with much betterdurability and less problem with yellowing. Two different techniques, chemiluminescense and real-time infrared spectroscopy, in combination are shown to be versatile tools to study the dryingperformance of oxidative drying coating systems.

7.2 Methyl esters as reactive diluents in linseed oil based coatings.

The use of fatty acid methyl esters as reactive diluents in air-drying systems have been evaluatedwith the techniques developed in the first part of the project. The general conclusion is that methyl


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esters can be used as diluent but that their influence on the properties must be matched with achange of the other components to obtain good overall final properties. The methyl esters slightlyincrease the amount of emissions compared to traditional vegetable oils but not to any large extent.This is proposed to be a consequence of the increased probability of intramolecular reactions for themethyl esters. The methyl esters further more reduce the overall reaction rate of the system and thecoatings become softer when using a methyl ester as a reactive diluent.

The overall conclusion is that traditional linseed oil based coatings can be improved both withrespect to their properties and environmental impact by changing the composition.

7.3 Emissions from the drying process

Volatile organic compounds are emitted during the drying process of linseed oil based surfacecoatings. These compounds are formed during the oxidation of unsaturated lipids. Compounds havebeen sampled and identified as mainly aldehydes and carboxylic acids. Some aldehydes areconsidered carcinogenic (formaldehyde and acetaldehyde), and both types of compounds are knownirritants.

Short chained and unsaturated aldehydes are generally not suitable for sampling onto an adsorbentsuch as Tenax®. The volatility and reactivity of these aldehydes makes them require a morepermanent way of adsorption. A chemical derivative named 2,4-dinitrophenylhydrazine (DNPH),reacts with aldehydes and ketones forming stabile hydrazones. DNPH can either be coated onto asorbent (e.g. silica, XAD-2 or C18) and used in a sample tube, solved in acetonitrile (AcCN) andused with an impinger, or soaked in a filter. Samplers have been created both for active and passivesampling. Sample tubes and filters are eluted with AcCN and the eluates are then analysed by HPLCwith UV or MS detection.

The influence of fatty acid pattern of the lipids on the emission process has been studied andclarified. Emissions generally peak after two days, but aldehyde emissions can be detected onemonth after the paint has been applied.

Occupational measurements have shown that concentrations of airborne formaldehyde can exceedoccupational limit values under certain circumstances. When properly used, the paint does not poseany serious health risks according to current knowledge.

Oils with different types of fatty acid composition of the triglycerides were investigated. There arethree main differences between the emission processes of a linolenic and a linoleic acid rich oil:

1. The most striking difference is the change to hexanal being the most abundant emittantinstead of it being propanal. This shows that the scission reactions occur mainly at the endunsaturation of the di- and triunsaturated fatty acid chains.

2. Secondly the time processes are different. The emission of the floor oil with the traditionallinseed oil peaked somewhere between three and eight hours whereas the Solin oil (Purolin)had its peak emission somewhere between 16 and 24 hours after application of the paint. Ofcourse, the times given are purely for comparative reasons. Depending on which productshave been tested and under which conditions, different time lines will be seen. Further, the


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emissions of the Solin oils were found to have a slower decline. At the end of theexperiments the main emission constituent (i.e propanal or hexanal) was approximately halfas abundant for the traditional oil as that for Solin oil.

3. The third difference was the peak height of the emission. Although the fast course of theemission process for the traditional oil made it hard to pinpoint the exact peak, the mainemittant’s maximum level was generally 150 % in comparison to that for Solin oil.

Other differences seen between the two types of oil were distinctions in the content of aldehydes(other than that of propanal/hexanal). Although traditional oil contains more unsaturated carbon-carbon bonds than Solin oil, the relationship was reverse regarding the emitted compounds Sincethe odour thresholds are especially low for the unsaturated aldehydes this could have a great impacton the perceived odour of respective oil. No scientific evaluations of perceived odour wereperformed, but at construction sites where products containing Purolin were used, users had foundthem to have a less offensive smell than traditional products.Finally a link was found in the prevalence between the most abundant aldehyde and the aldehydewith one carbon less in its molecule. In the case of hexanal being the most abundant species, anelevated amount of pentanal was also found and in the case of propanal, higher amounts ofacetaldehyde were observed.

Pre-polymerisation of the oil would be expected to have a great impact on the emission. The boiledoil seems to generate a higher emission in the beginning of the process, but the decline is faster thanthat of the raw oil.

The floor oils studied in contained a certain amount of Co/Zr/Ca-drier. An experiment was alsodone to see if different types of driers had different effects on the emission process. The cobalt ofthe original drier was exchanged for manganese.

Of the Purolin floor oil with Mn-siccativation, only 75 % of the required amount was absorbed bythe panels and of the traditional linseed oil with Mn-siccativation, only 84 % of the required amountwas absorbed. Results were normalized to facilitate a comparison. The emission rates for the oilswith manganese were greatly enhanced (Figure 7.1 and 7.2). The total emission during the first 10days increased by 56 % for Purolin and 77 % for the traditional linseed oil. Cobalt works as a topdrier, forming a skin over the still wet paint, while manganese affects the film throughout its depth.The increases in total emissions were partly due to the faster process, but since the decline was notso different between the different types of siccativation, it seems that manganese has an affect onthe scission reactions as well as the polymerisation process.


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0

50

100

150

200

250

0 2 4 6 8 10

Time (days)

Ald

eh

yde

s (n

mo

l/pa

ne

l)

Acetaldehyde

Propanal

Hexanal

0

50

100

150

200

250

0 2 4 6 8 10

Time (days)

Ald

eh

yde

s (n

mo

l/pa

ne

l)

Acetaldehyde

Propanal

Hexanal

Figure 7.1. Difference in emission profiles between A) Co-siccativated Purolin and B) Mn-siccativated Purolin.

B

A


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0

50

100

150

200

250

300

0 2 4 6 8 10

Time (days)

Ald

ehyd

es

(nm

ol/p

anel)

Acetaldehyde

Propanal

Hexanal

0

50

100

150

200

250

300

0 2 4 6 8 10

Time (days)

Ald

ehyd

es

(nm

ol/p

anel)

Acetaldehyde

Propanal

Hexanal

Figure 7.2 Difference in emission profiles between A) Co-siccativated traditional linseed oil and B)Mn-siccativated traditional linseed oil.

A

B


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8 Model systems for wood primer

It was decided to concentrate on low viscous product as linseed oil, boiled linseed oil, Purolin,boiled Purolin as well as a mixture of alkyd A 8818 and Purolin/Linutin. Because of the lowviscosity Linutin was used as a “diluent” for the systems.A standard drier composition containing Co (0,024 %), Zr (0,06%) and Ca (0,04%) calculated onthe oxidative drying matter was used for the primers. All samples were dispersed at low speed for10 minutes. The samples were left to rest for at least 16 hours before measuring the dryingproperties.

The primers and the reference containing organic solvent showed Newtonian behaviour. The secondreference was water borne and it showed a slightly shear thinning behaviour.

Table 7.1. Description and rheology of primer samples at 23°C.

Sample no. Description Torque element Viscosity / 92 s-1 Phase angle / 10 Hz

[gcm] [mPas] [Pa]

427-WP-L-1 Linseed oil/Linutin 7:3 3,73 24 81

427-WP-P-2 Purolin/Linutin 7:3 3,73 26 76

427-WP-Lb-3 Boiled Linseed oil/Linutin 7:3 3,73 69 78

427-WP-Pb-4 Boiled Purolin/Linutin 7:3 3,73 29 78

427-AP-5 A8818-SAL 650h/Purolin/Linutin 3:5:2

1,31 95 88

427-WP-L-6 Linseed oil/Linutin 75:25Co/Zr/Ca 0,024:0,061:0,04

1,31 29 82

427-WP-P-7 Purolin/Linutin 75:25C Co/Zr/Ca 0,024:0,061:0,04

1,31 30 83

427-WP-Pb-8 Boiled Linseed oil/Linutin 75:25Co/Zr/Ca 0,024:0,061:0,04

1,31 34 85

427-WP-ref 1-s Alkyd solvent borne 1,31 4 81

427-WP-ref 2 w Alkyd, water borne 1,31 144-16 58

The samples were applied with a brush on pine panels size 10 x 20 x 0.8 cm. Area 200 cm2. In orderto get a measure of the amount of primer that was able to penetrate into wood, the weight of the pinepanel was recorded before and after application. The coated panels were left in a horizontal positionfor 1 hour and then excess of primer was removed with a piece of paper. The panels were weighedafter 1, 24 and 96 hours and the weight loss/gain were recorded. The test condition was 23 ± 2°Cand at a RH of 50 ± 5%. The results are summarized in table 7.2. The weight change in % issummarized in table 7.3.


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Table 7.2. Amount of primer absorbed in the pine panels

weight after excess removed weight after 24 h weight after 96 h

Initial amountprimer/m2

amount primer absorbed in 1h/m2

amount primerabsorbed/m2

amount primerabsorbed/m2

(g ) (g ) (g ) (g )

427-WP-L-1 92,0 92,0 96,1 97,3

427-WP-P-2 91,0 82,5 88,5 90,7

427-WP-Pb-4 96,5 89,5 96,4 101,6

427-WP-L-6 95,5 75,0 81,7 82,6

427-WP-P-7 94,0 87,6 94,2 94,5

427-WP-Pb-8 90,5 72,7 79,1 78,2

427-WP-ref 1-s 93,0 69,1 49,9 41,6

427-WP-ref 2 w 96,5 52,2 34,9 27,7

Table 7. 3 Weight change in % after drying

weight change in % weight change in %

after 24 h after 96 h

427-WP-L-1 4,5 5,6

427-WP-P-2 7,3 9,9

427-WP-Pb-4 7,7 13,5

427-WP-L-6 8,9 10,1

427-WP-P-7 7,5 7,9

427-WP-Pb-8 8,8 7,6

427-WP-ref 1-s -31,4 -42,8

427-WP-ref 2 w -33,1 -46,9


The viscosity is highest for boiled linseed oil/Linutin 7:3 and A8818-SAL 650h/Purolin/Linutin 3:5:2. The other samples have acceptable low viscosity and the penetration test wasmade with them together with the 2 references. Sample 1, 2 and 4 have no drier. The drying wastested manually with finger touch on the panels and due to the penetration there was no difference indrying properties for the samples. The calcium drier is not fully accepted in the oils containingPurolin. Due to the oxidation the oil based samples have gained weight and boiled Purolin/Linutin7:3 have gained 13,5% weight after 96 hours drying in test condition 23 ± 2°C and at a RH of 50 ±5%.

9 Model systems for outdoor paint

9.1 Choice of formulations, with and without pigment

It was decided that outdoor prototype paints should be formulated, where both pigmented and non-pigmented products should be represented. Furthemore both boiled and standoils should be includedas well as alkyds. In table 8.1 is the final decision for a formulation plan shown.


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Table 8.1 Plan for formulationsProduct 1 Pigmented linseed oil paint with stand oil and WSProduct 1a Pigmented (boiled) linseed oil paint with stand oil and linutinProduct 2 Pigmented linseed oil paint with standard alkyd and WSProduct 3 Pigmented linseed oil paint with standard alkyd and LinutinProduct 4 Pigmented purolin paint with stand oil and linutinProduct 5 Pigmented purolin paint with Alkyd 1 and linutinProduct 6 Pigmented purolin paint with Alkyd 2 and linutinProduct 7 Pigmented (boiled) purolin paint with stand oil and linutinProduct 8 Pigmented (boiled) purolin paint with Alkyd 1 and linutinProduct 9 Pigmented (boiled) purolin paint with Alkyd 2 and linutinProduct 9a Pigmented (boiled) purolin paint with Std.alkyd and linutinProduct 10 Non-pigmented (boiled) linseed oil paint with stand oil and WSProduct 11 Non-pigmented (boiled) linseed oil paint with standard alkyd and WSProduct 12 Non-pigmented (boiled) linseed oil paint with Alkyd 1 and linutinProduct 13 Non-pigmented purolin paint with stand oil and linutinProduct 16 Non-pigmented (boiled) purolin paint with stand oil with linutinProduct 17 Non-pigmented (boiled) purolin paint with Alkyd 1 with linutinProduct 18 Non-pigmented (boiled) purolin paint with Alkyd 2 and linutinAlkyd1 = 65 % oil A8818Alkyd2= 49 % oil A8839Std. Alkyd = 65 % oil AL650

The formulation work was very time consuming as the amount of oxidative drying matter should bereasonably similar in the samples and the viscosity had to be at a level were it is possible to applythe paint/lacquer. In the end he viscosity varied in the range of 700-1000 mPas The pigment andfillers were also kept as conctant as possible, where titaniumdioxide, mica and talcum were used.

9.2 Choice of drier system

To choose a drier system several drying tests had to be done on one prototype. In the start Co, Zrand Ca was used, but it was decided at an early stage that the drying was not sufficient and thecolour of the paint became greenish. To obtain a “drier” coating the talcum content was raised to thesam level as mica and titaniumdioxide. After the reformulation work further drying tests had to bedone. Parallel to these tests gloss was measured. In the second series of drying tests an Al-drier wastested. This drier should be good for high solid products. After a large number of tests (>50) it wasconsluded that the best systems were Co (0,06%), Al (0,4%) and Ca (0,2%) or Mn (0,05%), Al(0,3%) and Ca (0,2%). In fact the Mn-system seemed to give a more glossy surface when testingPurolin-formulations. The Co-drier system was marked J3 and the Mn-drier system was markedCC1.

9.3 Physical characterization of model systems

The different paints/lacquers have been applied on glass and the hardness and the gloss has beenmeasured as a function of time. In figure 8.1 it can be seen that all the pigmented paints loose glosswith time. The prototype paints produced represent a rather broad range of gloss. The commercial


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paints are situated in the middle of this span. So from a gloss point of view the prototype paintsrepresent a reasonable model. It can also be seen that the Manganese drier system seems to givehigher gloss compared to the same paint with Cobalt. There is a significant difference with system8.3.

The non-pigmented products show the same tendencies with regard to gloss. The gloss on glasscompared to gloss on wood is not directly comparable.

Generally the hardness values are low for the prototype paints, see table 8.2. On the other hand soare the values for the commercial paints too.

Figure 8.1 White paint on glass (60 µµµµm) applied 24.07.03

30

40

50

60

70

80

0 20 40 60 80

Days after application

Glo

ss °

1a.1

1.2

2.2

3.2

4.2

5.11

6.3

7.2

8.3

9a.2

9.3

6.3-cc1

8.3 -cc1

Exteriør

KF

Lasol

Primolin


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Table 8.2 Hardness of prototype paints on glass.Sample Drier system 41 days 76 days

1a.1 J3 17 161.2 J3 18 182.2 J3 17 173.2 J3 17 174.2 J3 15 15

5.11 J3 9 96.3 J3 8 87.2 J3 13 138.3 J3 9 99a.2 J3 15 169.3 J3 8 8

10.2 J3 21 2010.2 J3 20 1911.2 J3 18 1812.2 J3 15 1413.2 J3 21 2016.2 J3 21 2117.2 J3 12 1218.2 J3 9 106.3 CC1 8 88.3 CC1 8 8

Exteriør Unknown 27 27KF Unknown 27 29

Lasol Unknown 18 19Primolin Unknown 23 24

9.4 Characterisation of chosen model systems, 2nd screening.

The next step was to compare chosen system with Cobalt and Manganese drier system respectively.The gloss is clearly higher when using Manganese drier systems for Purolin products. It is also ofinterest to conclude that the products with the short-oil alkyd have the highest gloss.

The hardness measurements in table 8.3 shows that the best prototypes have a comparable hardnessto the commercial linseed oil paint Lasol, . It can also be seen that the Mn drier system generallygives a little softer film than the Co system. The prototype 9b contains a Zn-pigment which makes ita little harder and comparable to Lasol.


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Figure 8.2 Gloss measured onprototypes on glass, 60µµµµm

40,0

50,0

60,0

70,0

80,0

90,0

100,0

0 5 10 15 20 25 30 35 40

Days

Glo

ss

2.2 j3

8.3 J3

9.4 J3

9b.2 J3

Lasol

Exteriør

8.3 CC1

9.4 CC1

9b.2 CC1

Figure 8.3 Hardness measure on prototype paint on glass, 60µµµµm applied

0

10

20

30

10 15 20 25 30 35 40

Days

Pen

du

lum

har

dn

ess

2.2 J3

8.3 J3

9.4 J3

9b.2 J3

Lasol

Exteriør

8.3 CC1

9.4 CC1

9b.2 CC1


The formulated prototype paints represent both traditional linseed oil paint as well as Purolin-basedpaint formulated on boiled oil and alkyd. Most of the prototypes are high solids and some of themare even 100 % dry matter. The drying of the prototypes was optimised for one Purolin-basedproduct to be similar to a commercial linseed oil paint. Conclusions:- Two drier systems worked well: One system with Co, Al and Ca, and one system with Mn, Al

and Ca. The Al-drier is normally used for high solid products.


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- The linseed oil products worked well with the Co-system.- The Purolin-based prototypes became softer with the Mn drier system, but got a higher gloss.

The gloss becomes even higher than the commercial products.- It also clear that Zinc-oxide gives a harder surface which makes the hardness close to

commercial linseed oil paint. It is clear that the linseed methyl ester softens the product.- If a short oil alkyd is used together with Linutin it is possible to get drying and a surface that is

tack-free.

10 Accelerated testing of durability

10.1 QUV-testing

QUV-testing is an accelerated weathering method were the panels are exposed to “sun-light” andwater. All the model paints were produced with the Co drier system and applied on wood. Twomodel paints were also produced with the Mn drier system. Each pine panel was applied with twolayers of paint and for each paint three panels were made. After application the painted panels wereclimatised for three weeks. Two panels for each paint was sent to Flügger for QUV-testing. Gloss,colour and hardness was measured before and after QUV testing.

It can be seen from the results that the commercial products are more durable. Especially Exteriör,but this paint is an alkyd emulsion paint. Lasol and KF are both commercail Linseed oil products, sothe comparison to these samples is of more importance. Most of the prototype paints have a higherdelta E (Colour difference) than the commercial products. Still the delta E after 103 hours is 2-3 forkommercial linseed oil paint. The prototype paints that have values close to this are 2.2, 6.3 and9a.2 for at least one panel. The first prototype 2.2 is a linseed oil based product, which means thateven if the colour difference is over 3 it is similar to the commercial products and it a reasonablegloss too. The prototypes 6.3 and 9a.2 have 1 thing in common they are both with Alkyd. It alsointerestins to see that the Mn-drier system gives a higher initial gloss for both 6.3 and 8.3. So theconclusion from this test serie is that it would be of interest to test some of the prototype paintsfurther. The obvious would be to compare Mn and Co drier systems more consequently in prototypepaint with alkyd2.


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Table 9.1 Results from QUV-testingMark Gloss before QUV Gloss after 28 h Gloss after 103h dE 28 h dE 103 h Hardness before

QUV1,a.1 (1) 31,9/38,6/31,5 8,7/9,9/8,8 5,9/3,4/2,6 4,39 8,61 151,a.1 (2) 45,6/41,7/39,3 19,6/19,2/19,0 5,5/5,0/4,6 4,1 6,66 141,2 J3 (1) 46,0/48,5/43,3 26,8/26/27,2 7,5/8,5 3,8 5,78 141,2 J3 (2) 46,7/43,1/53,6 17,9/17,8/20,7 6,1/5,0/4,6 4,23 8,64 15

2.2 (1) 36,7/38,6/47,5 19/20,4/26,4 14,5/12,1/11,2 4,74 8,66 142.2 (2) 50,0/46,3/50,1 37,1/32,7/32,9 17,9/15,0/17,4 2,56 3,34 153.2 (1) 45,5/42,3/33,0 23,7/21,2/17,6 8,9/6,4/5,8 4,31 7,53 163.2 (2) 45,9/38,8/34,2 14,7/16,5/19,4 5,2/6,2/7,2 5,82 9,63 174.2 (1) 29,3/31,9/32,1 9,0/9,8/10,1 4,8/5,4/5,1 5,44 8,53 124,2 (2) 30,7/24,9/24,6 15,0/15,0/14,9 4,4/3,8/3,9 2,33 4,66 12

5.11 (1) 15,9/16,5/17,6 5,9/6,7 3,9/4,0 3,65 7,28 115.11 (2) 22,4/21,5/19,6 7,7/7,3/7,7 4,5/4,2 5 8,43 86.3 (1) 21,4/24,6/22,1 10,1/10,4 5,5 3,46 7,55 86.3 (2) 21,3/23,1/24,7 10,5/8,2/10,2 4,2/4,4/4,5 2,71 3,88 97.2 (1) 31,4/40,2/35,1 8,7/8,7 3,8/3,8 4,46 10 127.2 (2) 37,5/34,1/33,3 8,5/9,4/10,7 4,2/3,4/3,5 4,1 6,11 128.3 (1) 24,3/26,8/25,2 8,0/8,1 5,1/4,9 4,25 8,25 98.3 (2) 24,8/28,1/24,4 8,1/7,2 3,5 5,12 10,02 79a.2 (1) 28,8/24,9/24,9 12,7/13 4,1/3,8 4,78 8,01 129a.2 (2) 21,9/24,6/21,0 15,3/15,9/15,8 5,6/8,1/5,7 2,02 3,96 139.3 (1) 37,1/47,6/40,5 14,0/20/17,4 5,8/4,7 3,16 7,37 79.3 (2) 51,4/49,5/52,0 19,9/22,1/23,4 8,8/10,6/11,2 2,96 4,54 6

10.2 (1) 37,4/35,4/39,5 10,2/7,6/8,9 3,5/1,6/1,7 7,17 15,44 1610.2 (2) 39,1/40,1/39,3 10,4/9,8/9,6 2,4/3,0/2,4 7,81 13,26 1411.2 (1) 28,7/26,9/31,3 8,9/7,8/7,3 3,3/3,5/3,6 9,49 15,35 1711.2 (2) 43,7/42,7/41,8 15,3/15,4/14,3 5,2/5,6/6,5 7,08 11,63 1412.2 (1) 35,6/26,4/24,2 7,5/5,7/5,6 2,8/2,2/2,3 6,74 13,32 1312.2 (2) 33,8/37,9/27,7 4,2/4,7/4,7 3,2/3,7/3,6 9,09 16,09 1213.2 (1) 49,3/46,9/40,5 8,9/7,5/6,7 4,9/4,3/2,6 8,96 17,59 1713.2 (2) 46,0/37,0/41,1 6,4/7,3/7,6 2,0/1,8/3,2 8,88 16,39 1716.2 (1) 39,1/38,8/37,3 5,9/6,0/5,6 2,6/3,3/2,6 9,65 17,45 1816.2 (2) 38,9/38,9/33,5 3,6/3,7/4,1 1,4/1,5/1,7 9,69 19,06 1717.2 (1) 22,2/24,8/21,8 4,0/3,9/3,9 2,0/2,0/1,9 7,91 16,65 1217.2 (2) 17,2/19,3/20,5 3,7/3,6/3,4 1,8/1,7/1,7 7,81 14,61 1118.2 (1) 29,7/30,8/27,6 3,1/3,4/3,4 2,2/2,0/1,9 9,11 17,36 718.2 (2) 29,6/33,4/37,1 4,1/5,1/5,2 1,8/2,0/2,2 7,61 16,67 7

6.3 CC1 (1) 30,6/28,0/27,6 7,1/6,8/6,9 2,9/2,6 3,49 7,67 76.3 CC1(2) 36,0/32,5/28,2 11,2/9,8/11,3 6,1/2,9/3,2 2,6 3,92 68.3 CC1 (1) 28,4/28,1/33,1 7,2/7,1/6,8 3,4/4,4/4,4 4,45 8,9 68.3 CC1 (2) 26,6/29,1/28,9 10,0/10,4/10,7 3,0/3,3/3,3 2,9 4,74 6Exteriör (1) 28,0/27,1/22,5 21,6/21,0/17,8 16/16,6/14,7 0,67 0,58 18Exteriör (2) 32,9/33,6/33,1 21,8/20,4/20,4 16,6/15,9/13,3 0,87 0,51 19

KF (1) 40,9/46,6/37,7 27,8/17,2/12,5 6,7/7,0 1,98 2,9 23KF (2) 45,5/44,8/46,3 59,4/59,8/59,7 44,0/44,3/39,4 2,19 2,88 23

Lasol (1) 32,5/27,2/28,5 15,4/12,7/17,0 19,1/18,2/22,2 1,66 2,61 24Lasol (2) 33,8/32,5/32,4 24,1/23,3/22,9 20,3/19,6/19,0 1,76 2,11 22

Primolin (1) 34,5/32,4/37,0 27,1/24,6/27,8 20,3/21,5/22,9 0,95 1,86 19Primolin (2) 31,9/31,8/27,7 26,2/28,3/24,5 23,8/24,7/23,1 1,14 2,22 18


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The QUV tests show that there are some Purolin-based coatings that are rather good. There areindications on that the Mn-system is to prefer in the Purolin-based coatings. This should be furtherinvestigated. One of the coatings with short oil alkyd seems promising so this should be combinedwith the Mn drier system.

11 Evaluation of linseed raw materials for wood protection

11.1 General trends

The modified linseed oil (Purolin) has a number of advantages. It seems to penetrate better thantraditional linseed oil. It can dry without using Cobalt driers. It is here suggested that Manganesedriers can be used and gives Purolin-based paints higher gloss, even though it becomes softer thanwith Co. The water up-take (floor oils) is less than for the traditional linseed oil. It is also possibleto make paints with a 100 % dry matter using a short oil alkyd together with the linseed methyl esteras a thinner.

Analysis of the curing performance of linseed oil coatings is changed when changing the fatty acidpattern in the oils. Traditional linseed oil, rich in linolenic acid, dries rapidly but the coating suffersfrom high degrees of residual unsaturation in the cured film. A linseed oil variety rich in linoleicacid is shown to exhibit a very different behaviour. This oil will produce slightly softer films butwith a significantly lower amount of residual unsaturation, no problem with skin formation, andgood through cure.

Analysis of emissions show that there are differences between the emission processes of a linolenicand a linoleic acid rich oil there a change to hexanal being the most abundant emittant instead ofpropanal. The time processes are also different. The emission of the floor oil with the traditionallinseed oil peaked somewhere between three and eight hours whereas the Purolin had its peakemission somewhere between 16 and 24 hours after application of the paint.

These analytical results explain the practical results with regard to that Purolin gives a softer film.But it also explains why the two types of oil need different drier systems.

11.2 Need for development

The short oil alkyd concept should be investigated further. An optimisation of the VOC-freeformulation with Mn drier system could become a very attractive combination from anenvironmental point of view. This concept should be made broader for example making a corrosiveprotection primer. This could be used for example for metal parts on windows etc.

11.3 Expectations to future

Due to the new VOC-directive we expect that the interest for alternative products will grow as thesolvent-based wood protection products diminish on the market.


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12 References

1. Information about Dapro 5005 and Dapro 7007 driers from Elementis: “Dapro 5005 and 7007 –Why an alternative to Cobalt driers?”

2. Tuck N.; “Waterborne and Solvent Based Alkyds And their End User Applications”; SurfaceCoating Technology – Volume VI”; SITA Technology/Wiley; 2000.

3. Oldring P. & Hayward G.; “Resins for Surface Coatings”; Surface Coating Technology –Volume I”; SITA Technology; 1995.

4. Owen D.J.; “Printing Inks for Lithography”; SITA Technology; 1990.

5. Oldring P. & Hayward G.; “Resins for Surface Coatings”; Surface Coating Technology –Volume II”; SITA Technology; 1995.

6. Wicks Z. W.; “FILM FORMATON” Federation series on coatings technology, 1986.

7. IRL (Information Research Limited); “A profile of the European paint industry”; 12 edition;June 1998.

8. www.servo.nl/performance/coating/index.htm (18-06-2001) Internet information fromCONDEA Servo.

9. www.omgi.com (25-05-2001) Internet information from OMG.

10. Wiskemann R; “Development in Drier Technology for Air Drying Waterborne Coatings” Färgoch Lack Scandinavia, no. 5, p. 4-9; 2000.

11. Lambourne, R. “Paint and Surface Coatings”; Ellis Horwood Limited 1987.

12. DRI-RX 19 LC-ETM : The chelator/accelerator for driers for coatings and inks. TECH Solutions,OMG, Issue 04/98.

13. Todd, R.E.; “Prinitng Inks – Formulation principles, manufacture and quality control testingprocedures”; Pira Printing Ink Guide Series, 1994.

14. Leach, R.H.; “The Printing Ink Manual”; Fourth edition; Van Nostrand Reinhold (International);1988.


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13 Publications

1. C. Stenberg, M. Svensson, M. Johansson “A study of the drying of linseed oils with differentfatty acid patterns using RTIR-spectroscopy and Chemiluminescense (CL)” submitted toIndustrial Crops and Products (2003)

2. M. Svensson, C. Stenberg, J. Samuelsson, M. Johansson, ”Förbättrade Vegetabiliska Oljor förFärger – del 1.” Svensk Frötidning, 13-15, 1, (2003)

3. M. Svensson, C. Stenberg, J. Samuelsson, M. Johansson, ”Förbättrade Vegetabiliska Oljor förFärger – del 2.” Svensk Frötidning, 17-18, 2, (2003)

4. P. Fjällström, M. Johansson, M. Svensson, ”När Linoljefärg Torkar” Byggnadskultur, 24-26, 4,(2003)

5. C. Stenberg, E. Wallström, M. Svensson, M. Johansson, ” Drying of linseed oils using reactivediluents” manuscript in preparation (2004)

14 Conference presentations

1. “Woodcoatings – foundation for the future”, Hague, The Netherlands, Oktober 2002, M.Svensson, C. Stenberg, M. Johansson Drying of different linseed oils studied with RTIR andchemiluminescence (oral).

2. “Nordiska Polymerdagarna”, Copenhagen, Denmark, August 2003, C. Stenberg and M.Johansson Drying of new linseed oils as coatings studied with real-time infrared spectroscopyand chemiluminescence (oral).

voc-fria linoljebaserade tr¤skyddsprodukter voc-free linseed oil

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