Silicone materials have been used for manyyears to improve the surface appearanceand properties of various coatings sys-tems. When added to coatings formula-tions, silicone additives can improve wet-

ting of substrates and give effective defoaming, block-ing resistance and mar resistance. This paper discuss-es a new class of materials that are being developed.

Traditionally, organo modification of silicones hasinvolved incorporating polyether, alkyl and phenylgroups onto the silicone backbone. For this study,carbinol functionality has been incorporated onto thesilicone backbone using a new capability in DowCorning to functionalize silicone resins/polymers withorganic moieties etc. These novel materials will becapable of co-reacting with many organic curechemistries, resulting in improved compatibility andother performance aspects of the final coating.

This paper describes the initial study of carbinolfunctional materials where prototype materials werecold blended into standard parquet lacquer formula-tions. The next stage of the program will investigate

chemically reacting the functional groups into theresin. A range of carbinol fluid structures were evalu-ated in terms of their performance in UV and water-borne parquet-type formulations. The silicone chem-istry is described, as well as the relationship betweenchemical structure and suitability for particular par-quet lacquer formulations.

Silicone Additive Benefits for Parquet CoatingsFor many coatings systems, the regulatory drive awayfrom solventborne towards waterborne formulationshas created performance issues. Coating formulatorsare less able to rely on the flow and leveling benefitsprovided by solvents. In addition, waterborne poly-mers may not provide the required level of gloss, foamcontrol, blocking and mar resistance. New formula-tions include non-VOC-contributing additives to pro-

A P R I L 2 0 0 5 / www.pcimag.com86

By Donna Perry and Vicky James/Dow Corning Ltd., Barry, UK; and Gerald Witucki/Dow Corning, Midland, MI

CH3CH3CH3CH3| | | |

R- Si - O (- Si - O )n (- Si - O )m -Si - R| | | |

R = (CH2)3 (OCH2 CH2)x(OCH2CH)yOX|

or R=CH3

CH3 CH3 R CH3

CH3

Figure 1/General structure of silicone-polyether copolymers.

Table 1/UV solventless parquet lacquer formulation, courtesyof UCB.

Ingredients Parts by WeightEbecryl 6040 219.7OTA 480 263.2Benzophenone 17.6Irgacure 651 17.6Aktisil MAM-R 481.9Total 1000

Table 2/Waterborne UV parquet lacquer formulation, courtesyof Alberdingk Boley.

Ingredients Parts by WeightAlberdingk Lux 399 951.0Dow Corning 68 Additive 3.0Ultralube D816 25.0Acematt TS 100 5.0DSX 300 6.0Irgacure 500 10.0Total 1000

Carbinol FunctionalSilicon-Based Technologies

for CoatingsCarbinol FunctionalSilicon-Based Technologies

for Coatings

vide the needed performance. Silicone additives arewell suited for use in parquet coatings to protect thecoating surface from mechanical damage during pro-cessing, transport and use. They can also improve thevisual appearance by helping to produce a smoothcoating surface free of defects.

Current Silicone TechnologyTraditionally, silicone polyether technology has beenused to impart slip, wetting, leveling and defoaming.These copolymers will have typical surfactant fea-tures, i.e. hydrophobic and hydrophilic segments. Theratio of the hydrophobic/hydrophilic segments isimportant to achieve the required compatibility bal-ance. A high hydrophobic content may lead to de-wet-ting defects e.g. fish eyes, craters. On the other hand, ahigh hydrophilic content can increase the solubility ofthe copolymer so that there is no driving force foraccumulation at the coating/air interface during thedrying process.

Figure 1 shows the general structure of a silicone-polyether copolymer. The polyether chains can beattached at points along the length of the siliconebackbone, giving a comb-like structure. They can alsobe attached to the ends of the silicone polymer, givingtelechelic, linear structures. The architecture of thecopolymer has a profound effect on the behaviour asan additive. Optimized structures have been identifiedby designed experimentation to give suitable combina-tions of compatibility and desired effect, such as slip,leveling or wetting and defoaming. Compatibility isparticularly important in clear parquet coatings,where gloss reduction or haze cannot be tolerated.

This type of silicone technology is already widelyknown. This paper will attempt to build on the currentunderstanding by evaluating three alternative poly-mer structures with a carbinol functional groupattached to the silicone backbone:• ABA linear silicone carbinol fluid with (EO)1OH

functionality;• Silicone carbinol fluids with novel hydrophilic

groups;• Carbinol functional silicone resins.

ABA Linear Silicone Carbinol Fluid with(EO)1OH FunctionalityPerformance in UV Solventless Parquet CoatingFormulationThe ABA linear samples tested varied in the length ofthe siloxane unit. Though these materials are soluble

in polar solvents, they are extremely hydrophobic and,therefore, not water soluble or dispersible. Tests wereperformed in a UV system only. The evaluations ofABA linear carbinol functional fluids were performedusing the formulation shown in Table 1.

The performances of these various molecules inthese formulations were studied, and the followingproperties were evaluated: mar resistance; gloss/haze;slip/friction; and surface appearance (leveling, com-patibility).

Mar resistance is an important property for parquet.The three materials all have the effect of improvingthe mar resistance compared to no silicone addition,as shown in Figure 2. The mar resistance also increas-es as the number of siloxane units in the siloxanebackbone increases in number from left to right (1 =excellent appearance, 5 = poor appearance).

Another important property is the compatibility interms of no cratering or leveling irregularities. The sil-icone fluids should have no negative effects on theappearance of the final coating. The results in Figure3 demonstrate an improvement in the appearance asthe number of siloxane units in the siloxane backboneincreases in number from left to right (1 = excellentappearance, 5 = poor appearance).

P A I N T & C O A T I N G S I N D U S T R Y 87

0.01.02.03.04.05.0

Cont

rol

ABA

Carb

inol

1AB

A Ca

rbin

ol 2

ABA

Carb

inol

3

Mar

res

ista

nce

0.5% add1.0% add

Figure 2/Mar resistance of ABA linear silicone carbinol fluid with (EO)1OHfunctionality in UV solventless parquet lacquers.

1

2

Cont

rol

ABA

Carb

inol

1AB

A Ca

rbin

ol 2

ABA

Carb

inol

3

Crat

erin

g 0.5% add1.0% add

Figure 3/Appearance of ABA linear silicone carbinol fluid with (EO)1OHfunctionality in UV solventless parquet lacquers.

The slip performance or coefficient of friction wasalso tested and compared to the control. This also givesa measure of whether the silicone tested comes to theair-liquid interface. As can be seen in Figure 4, the slipis reduced, showing their presence at the surface forall three molecules tested.

Performance in Waterborne Parquet Lacquer FormulationsThe advantages of moving to waterborne systems interms of healthier, safer and environmentally moreacceptable coatings are obvious. However there is alsoone significant disadvantage. Waterborne coatingsusually contain surfactants (e.g. binder, dispersant,

wetting agent etc), which have the negative effect ofstabilizing foam from air incorporation during the pro-duction and application of the coating. However, it isimportant for these waterborne coatings to containwetting agents due to the high surface tension ofwater, which can cause surface defects such as cratersand poor wetting on substrates. Dow Corning pro-motes various silicone polyether technologies to beused as wetting agents. One successful product inparticular, a trisiloxane polyether (Figure 5), is sold asan anti-crater additive and acts by lowering the sur-face tension of the liquid coating and thus improvessubstrate wetting.

This product also has good compatibility as seenwith both UV and air-drying waterborne parquet lac-quers (Figure 6).

The addition of these surfactant-type siloxane mol-ecules, although achieving excellent wetting even ondifficult-to-wet substrates, can sometimes have a neg-ative effect on the foam behaviour of the coating. Insome cases, the trisiloxane silicone polyether technol-ogy can lead to foam stabilization. This problem is usu-ally overcome by the addition of defoamers, which cansometimes have negative effects on the final appear-ance of the coating.

A range of silicone carbinol fluids with novelhydrophilic groups were synthesized for this evalua-tion with the hope that good wetting and good com-patibility could be achieved without compromisingthe foaming behaviour of the liquid coatings.

Five different structures were designed and perfor-mance tested. These structures contained the samesiloxane chain length but varied in the nature of thecarbinol functional hydrophilic group. (The exactnature of these structures is proprietary.)

The evaluations of these fluids were performedusing the formulations shown in Tables 2 and 3.

The following properties were tested in these formu-lations:

1. Mar resistance2. Gloss/Haze3. Slip/Friction4. Surface appearance (leveling, compatibility)5. Foam stability6. BlockingThe molecular weight and mol % hydroxy units in

the fluid dictate the compatibility of the silicone-carbinol fluids in the parquet lacquers (Figure 7).

When mixed at high shear, these materials did notshow foam stabilization typically seen with wettingsurfactants (Figure 8).

Carbinol Functional Silicon-Based Technologies for Coatings

A P R I L 2 0 0 5 / www.pcimag.com88

CH3

(EO)nR

(CH3)3-Si-O-Si-O-Si-(CH3)3

(CH2)3

Figure 5/Structure of a trisiloxane.

0.000.100.200.300.400.50

Cont

rol

ABA

Carb

inol

1AB

A Ca

rbin

ol 2

ABA

Carb

inol

3

Coef

fici

ent

of F

rict

ion

0.5% add1.0% add

Figure 4/Coefficient of friction of ABA linear silicone carbinol fluid with(EO)1OH functionality in UV solventless parquet lacquers.

Table 3/Waterborne air-drying parquet lacquer formulation,courtesy of BASF.

Ingredients Parts by WeightDowanol PnB 40.01,2-propylene glycol 10.0Dowanol DPM 20.0Dow Corning 68 Additive 5.0Deuteron MK 10.0Water 30.0Luhydran A 848S 800.0Butyl glycol 20.0Poligen WE1 45.0Total 980

The addition of the silicone-carbinol fluids to thelacquers did not adversely affect the slip, blocking orgloss of the final coating. No change in mar resistancewas observed.

The effect on wetting was measured by surface ten-sion (Figure 9). With the new silicone-carbinol fluidsevaluated, only a small change in surface tension wasobserved.

At this time, the trisiloxane material, with three Siatoms and pendant EO groups, still gives the bestresults for wetting. The new hydrophilic silicone-carbinol fluids do not give the problem of foam stabi-lization as seen with the trisiloxane material, but thedegree of polymerization of the silicone backboneand/or the molecular weight of the hydrophilic groupis clearly still too high to achieve the excellent mobili-ty in solution and very efficient packing at the inter-face achieved by the trisiloxane material.

This class of materials was tested to determine theireffect on the hydrophilicity and oleophobicity of thecoating. This was done by incorporating the materialsin an acrylic binder (Rhoplex SG-30, courtesy of

P A I N T & C O A T I N G S I N D U S T R Y 89

With Trisiloxane SPE Without Additive

Figure 6/Compatiblity of trisiloxane.

0.5

1.5

2.5

Cont

rol

Tris

iloxa

ne S

PECa

rbin

ol fl

uid

1Ca

rbin

ol fl

uid

2Ca

rbin

ol fl

uid

3Ca

rbin

ol fl

uid

4Ca

rbin

ol fl

uid

5

Crat

erin

g

0.5% add1.0% add5.0% add

Figure 7/Appearance of silicone carbinol fluids with novel hydrophilic groups ina waterborne air-drying parquet lacquer (Formulation 3).

Rohm and Haas), and measuring the contact angle ofwater and oil on the cast film (Table 4). Reduced con-tact angles were found with water showing thesematerials will increase hydrophilicity; however theeffect on oleophobicity was minimal.

The next stage in the development of these materi-als will be to look at lowering the degree of polymer-ization of the silicone backbone and the molecularweight and structure of the hydrophilic group toachieve excellent wetting without foam stabilization.

Finally, the next class of carbinol functional materi-als, carbinol functional methyl resins, was evaluatedin formulations included previously. A comparisonwas also made to non-functional methyl resins. Mate-rials are not soluble in water and therefore were deliv-ered into the coating in emulsion form.

Adding carbinol functionality alone to methylresins can lead to a decrease in compatibility of theresin in the lacquer, for both UV and air-drying water-borne systems. Examples of this are given in Figures10 and 11. However, it can bee seen that substitutingphenyl groups into the resin can overcome the issue ofpoor compatibility.

Earlier we saw that linear silicone-carbinol fluidsgave no benefit in mar resistance in waterborne coat-ings. The data in Figure 12 shows the positive benefitof adding a more rigid, three-dimensional structure tothe coating to improve mar resistance. The substitu-tion of phenyl groups into the carbinol resin alsoimproves the mar resistance at lower addition levelscompared to the non-functional methyl only resins.

Of course it is important to ensure that other prop-erties required in the coatings remain unaffected bythe addition of the silicone resins e.g., gloss, slip. Fig-ures 13 and 14 illustrate that in the UV and air-dryingformulations tested, the phenyl substituted carbinolresins had no negative impact on slip or gloss.

ConclusionsSilicone additives have progressed enormously sincethe first use of PDMS fluids in solventborne coatings.New chemical structures and delivery forms promise

Carbinol Functional Silicon-Based Technologies for Coatings

A P R I L 2 0 0 5 / www.pcimag.com90

0123456

Cont

rol

MQ

Carb

inol

Carb

inol

-Phe

nyl

EO

Crat

erin

g 2.5% addition5% addition10% addition

Figure 10/Appearance of carbinol functional silicone resins in waterborne air-drying parquet lacquer (Formulation 3).

012345

Crat

erin

g 2.5% addition5% addition10% addition

Cont

rol

MQ

Carb

inol

Carb

inol

-Phe

nyl

EO

Figure 11/Appearance of carbinol functional silicone resins in waterborne UVparquet lacquer (Formulation 2).

0.5

0.7

0.9

Cont

rol

Tris

iloxa

ne S

PECa

rbin

ol fl

uid

1Ca

rbin

ol fl

uid

2Ca

rbin

ol fl

uid

3Ca

rbin

ol fl

uid

4Ca

rbin

ol fl

uid

5

Den

sity

aft

er h

igh

shea

r m

ixin

g 28

00 r

pm, 1

min 0.5% add

1.0% add5.0% add

Figure 8/Appearance of silicone carbinol fluids with novel hydrophilic groups ina waterborne UV-drying parquet lacquer (Formulation 2).

10

20

30

40

Cont

rol

Tris

iloxa

ne S

PECa

rbin

ol 1

Carb

inol

2Ca

rbin

ol 3

Carb

inol

4Ca

rbin

ol 5

Surf

ace

tens

ion

mN

/m

0.5% add1.0% add5.0% add

Figure 9/Surface tension of silicone carbinol fluids with novel hydrophilicgroups in a waterborne UV-drying parquet lacquer (Formulation 2).

Adding carbinol functionality aloneto methyl resins can lead to adecrease in compatibility of theresin in the lacquer, for both UV andair-drying waterborne systems.

Carbinol Functional Silicon-Based Technologies for Coatings

A P R I L 2 0 0 5 / www.pcimag.com92

even greater improvements. This paper summarizes

the performance of different silicone technologies invarious parquet coating formulations.

Short chain ABA linear silicone-carbinol fluids with(EO)1OH functionality have shown good compatibilityin UV solventless coatings. They can migrate to thecoating surface, giving increased mar resistance andslip. Their hydrophobicity does not allow them to beused directly in waterborne coatings. Further work isplanned using an emulsion delivery system to deter-mine their effects in waterborne coatings.

Increasing the hydrophilic character of the silicone-carbinol fluids allows them to be directly incorporatedin waterborne systems. Their compatibility in water-borne coatings is dependent on the balance betweenthe length of the siloxane backbone and the molecularweight of the hydrophilic group. They do not causefoam stabilization seen with other surfactants, butmore work is needed on optimizing the structures ofthese materials if benefits in wetting and mar resis-tance are to be achieved.

Moving from a linear fluid to a rigid, three-dimen-sional resin brings improvements in mar resistancewithout adversely affecting the slip or gloss level of thecoating. Carbinol functional resins show improvedmar resistance compared to non-functional resins, butthis must be balanced with phenyl functionality toensure compatibility in the coating. Further work isplanned to determine improvements in performanceby reacting carbinol resins with organic binders. �

AcknowledgementsDonna Perry and Vicky James are technical service specialists for Dow

Corning Europe. Jerry Witucki is a technical service specialist with Dow

Corning Corporation. The authors wish to thank Frances Fournier, Gary

Wieber and Mike Ferritto at Dow Corning Corporation and Katrin Lan-

gosch at Worlee Chemie GmBH for their valuable contribution to this

work. They would also like to thank UCB, Alberdingk Boley, BASF and

Rohm and Haas for their contributions to test formulations.

References1. Owen, MJ, “The Surface Activity of Silicones: A short

review”, I&EC Prod. Res. Dev., 10 (1980), 97.2. W.H. Pushaw III in Handbook of Coatings Additives

(L.J. Calbo, ed.), Marcel Dekker, Inc., New York, 1987,p.271.

For further information contact, Donna.perry@dowcorning.com,

Vicky.james@dowcorning.com, or Gerald.Witucki@dowcorning.com.

This paper was presented at the European Coatings Conference “Parquet

Coatings III”, which took place November 2004, in Berlin. Information is

available at Vincentz Network, amanda.beyer@coatings.de.

00.020.040.060.080.1

C of

F

2.5% add5% add10% add

Cont

rol

MQ

Carb

inol

Carb

inol

-Phe

nyl

EO

Figure 13/Slip of carbinol functional silicone resins in waterborne UV parquetlacquer (Formulation 2).

0

20

40

60

80

Cont

rol

MQ

Carb

inol

Carb

inol

-Phe

nyl

EO

Glo

ss 8

5 de

g

2.5% add5% add10% add

Figure 14/Gloss of carbinol functional silicone resins in waterborne UV parquetlacquer (Formulation 2).

Table 4/Contact angle measurements at 1% additive addition into an acrylicbinder.

Water Contact Angle Oil Contact Angle Reference (deg) (deg)Acrylic binder alone 43 50.7Carbinol 1 <15 52.8Carbinol 2 <15 56.8Carbinol 3 <15 48.8Carbinol 4 <15 58.6Carbinol 5 <15 43.0

012345

Mar

res

ista

nce 2.5% addition

5% addition10% addition

Cont

rol

MQ

Carb

inol

Carb

inol

-Phe

nyl

EO

Figure 12/Mar resistance carbinol functional silicone resins in waterborne air-drying parquet lacquer (Formulation 3).