research article polymerization of oriental lacquer...

Research ArticlePolymerization of Oriental Lacquer (Urushi) withEpoxidized Linseed Oil as a New Reactive Diluent

Takahisa Ishimura1 and Takashi Yoshida12

1Department of Bio and Environmental Chemistry Kitami Institute of Technology 165 Koen-cho Kitami 090-8507 Japan2Research Center for Environmentally Friendly Materials Engineering Muroran Institute of Technology 27-1 Mizumoto-choMuroran Hokkaido 050-8585 Japan

Correspondence should be addressed to Takashi Yoshida yoshidachemkitami-itacjp

Received 24 February 2015 Accepted 31 May 2015

Academic Editor Wen Shyang Chow

Copyright copy 2015 T Ishimura and T Yoshida This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A hybrid lacquer (HBL) paint prepared by combining a natural kurome lacquer (KL) paint and an amino silane reagent forexample N-(2-aminoethyl)-3-aminopropyl triethoxysilane (AATES) produced a polymerized film faster than the KL paint aloneHowever the viscosity of the HBL paint was too viscous for easy handling Addition of 10wt of an epoxidized linseed oil ELO-6with 64mol epoxidation as a reactive diluent to the HBL paint decreased the viscosity by 12 from 25476mPasdots to 12841mPasdotsand improved the ease of coatability The polymerization mechanism was elucidated by NMR measurements of extracts from theresulting polymerization films suggesting that amino groups in the HBL paint reacted with epoxy groups of ELO-6 in the lacquermatrix and then the complex reacted with double bonds of the urushiol side-chain by autooxidation and cross-linking reactionsto give a hard polymerized film with a high quality of color and gloss These results indicate that the addition of ELO-6 improvedthe polymerizability of both KL and HBL paints without decreasing the quality of the resulting films

1 Introduction

Oriental lacquer (urushi) sap collected from lacquer trees hastraditionally been the only natural product that is polymer-ized by an enzyme laccase without any volatile compoundsto give a cross-linked polymerized filmTherefore the lacquerhas been used as a natural coating material for containerstableware and furniture with high durability and a beautifulglossy surface for more than several thousand years in Japanand other Asian countries [1ndash3] Natural lacquer is alsoexpected to be an environment-friendly paint for the nextgeneration

Lacquer trees are of Asian origin and are known tocomprise mainly three species Rhus verniciflua in East Asia(Japan China and Korea) Rhus succedanea in South Asia(Vietnam and Taiwan) and Melanorrhoea usitata in SouthEast Asia (Thailand Cambodia and Myanmar) [1 2] Thelacquer tree sap is aWO type emulsion and consists of lipids

(urushiol laccol and thiol) as themain components acetone-insoluble components (polysaccharides glycoproteins andenzymes) as emulsifiers and dispersing agents and water [4]

In the polymerization of lacquer urushiol which is amixture of 3-alkenylcatechols is radically polymerized bylaccase in the first stage and then the polymer is autooxidizedby air in the second stage to give cross-linked polymers [5ndash7] However the polymerization is affected by temperatureand humidity and the polymerization conditions are limitedthat is 30∘C temperature and 70 humidity are necessaryover a polymerization time of more than one month Themoisture is necessary for the reoxidation of laccase in thepolymerization filmswith oxygen in the air Furthermore theautooxidation in the second-stage polymerization is inhibitedby the phenolic hydroxyl groups of the catechol ring Thesephenolic hydroxyl groups which act as an antioxidantare decreased by the enzymatic oxidation in the first-stagepolymerization and this polymerization obstructs contact

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2015 Article ID 782843 7 pageshttpdxdoiorg1011552015782843

2 International Journal of Polymer Science

with unsaturated side-chains [8] Therefore a long time isnecessary to complete polymerization

Recently we developed a hybrid lacquer (HBL) paint toimprove the polymerizability of kurome lacquer (KL) paint[9]When an amine-functionalized organic silane compound(amino silane regent)119873-(2-aminoethyl)-3-aminopropyl tri-methoxysilane (AATMS)119873-(2-aminoethyl)-3-aminopropyltriethoxysilane (AATES) or119873-(2-aminoethyl)-3-aminopro-pyl methyl dimethoxysilane (AAMDMS) was added tothe KL paint the polymerization time was shortened to6 h in humidity below 55 and temperature at 20∘C [1011] Therefore the HBL paint is expected to increase theproduction of lacquer wear However the HBL paint hadhigher viscosity than the original KL paint due to the increaseof polymerized and polycondensed compounds in the first-stage polymerization [12] Viscosity of lacquer paint ingeneral decreases the handling properties compared to thatof other coating methods of spraying dipping and paintingby brush

Plant oil linseed oil has been often used as a diluent todecrease the viscosity of lacquer paint and to increase thegloss of the resulting polymerized lacquer film [13 14] Afterpolymerization however linseed oil sometimes oozes out ofthe polymerized film Thus improvements in polymerizabil-ity are required for the general use of lacquer paints andmaterials in the future In this paper we report a new reactivediluent prepared by the epoxidation of linseed oil [15ndash21] Wefound that the epoxidized linseed oil ELO-6 with 64molepoxidation worked effectively in polymerization of bothHBL and natural KL paints without any volatile componentsThe drying properties and hardness after polymerization oftheHBL andKLpaintswith epoxidized linseed oils as reactivediluents are reported The polymerization mechanism ofHBL and KL paints with the epoxidized linseed oil wasevaluated by NMR measurements of acetone extracts fromthe corresponding polymerization films

2 Materials and Methods

21 Materials Kurome lacquer (KL) paint was purchasedfrom Dohichu Shoten (Osaka Japan) The KL paint usedhere was composed of urushiol (896) water (41)and acetone-insoluble compounds (63) such as polysac-charides glycoprotein and laccase 119873-(2-aminoethyl)-3-aminopropyl triethoxysilane (AATES) was obtained fromShin-Etsu Silicone Co Ltd (Tokyo Japan) The linseed oil(LO) used was reagent grade

22 Measurements The drying of lacquer paints was evalu-ated by using drying time recorder (Taiyu Equipment OsakaJapan) according to the JIS-K-5400 standards The hardnessof polymerized films was determined using mechanical pen-cil hardness tester (Yoshimitsu Seiki Tokyo Japan) accordingto the JIS-K-5600 standards Viscosity was measured byBrookfield cone-plate type viscometer DV-II+The 500MHz1H NMR spectrum in CDCl

3as a solvent at 25∘C was

obtained by using JEOL JNM-ECA500 spectrometer withtetramethylsilane as a reference (000 ppm) Color scales ofpolymerization films were determined by the color standard

(119871lowast119886lowast119887lowast system) using BYK-Gardner Gmbh colorimeter(Germany) Spectroguide 450 was usedThe symbols 119871lowast 119886lowastand 119887lowast mean brightness and the ratios of red (+) to green (minus)and yellow (+) to blue (minus) respectively The gloss of the poly-merized filmswasmeasured by a glossmeter PG-1M (NipponDenshoku Japan) Thermogravimetric analysis (TGA) of thepolymerized films was performed using Shimadzu DTG-60 thermoanalyser at the heating rate of 10∘Cmin underN2atmosphere The glass transition temperature (tan 120575)

of polymerization films was recorded using a rigid-bodypendulum-testing machine RPT-3000W (AampD Co LtdJapan)

23 Synthesis of Epoxidized Linseed Oil [21] A typical proce-dure for the epoxidation of linseed oil ELO-6 with 64molepoxidation is as follows To a solution of linseed oil (440 g500mmol) in CHCl

3(150mL) were added 06 g of phos-

photungstic acid (002mmol) and 0215 g of cetylpyridiniumchloride (006mmol) After 30 hydrogen peroxide solution(567 g 500mmol) was added the mixture was refluxedfor 6 hours with vigorous stirring After cooling to roomtemperature the separated CHCl

3layer was washed by

distilled water twice and then dried over anhydrous sodiumsulfate After filtration and evaporation to remove sodiumsulfate and CHCl

3 respectively epoxidized linseed oil (ELO-

6) (420 g) with 64mol epoxidation was obtained in 95yield The epoxidized linseed oil was used without furtherpurification

24 Polymerization of Hybrid Lacquer Paint with ELO-6To the KL paint (100 g) was added 10 g of epoxidizedlinseed oil (ELO-6) as a reactive diluent The mixture wasstirred for 30min at room temperature and then 05 g ofhydrolyzed AATES that had been prepared by addition ofwater was added The mixture was further stirred for 30minand then coated at 76 120583m thickness on a glass plate byusing a film applicator The lacquer-coated glass plate wasmaintained at 25∘C under 60 humidity for the enzymaticand autooxidative polymerization

25 Extraction of Polymerization Films by Acetone To inves-tigate the polymerizability of epoxidized linseed oil (ELO-6) the polymerization films of the KL paint with ELO-6and AATES after polymerization for 2 h 24 h and 168 h (7days) respectively were extracted by acetone The extractswere identified by the 1H NMR measurements The resultsare shown in Figure 3

3 Results and Discussion

31 Synthesis of Epoxidized Linseed Oils In general a smallamount of oil of linseed (Linum usitatissimum) is usedas a diluent of KL paint to decrease the viscosity andimprove the gloss of the surface of the polymerized filmHowever linseed oil often oozes out of the polymerizationfilm Therefore epoxidized linseed oils as a new reactivediluent were synthesized by the epoxidation of linseed oilwith hydrogen peroxide (H

2O2) and heteropoly acid-CPC

system as a catalyst Table 1 shows the viscosity of the KL

International Journal of Polymer Science 3

Table 1 Viscosity of kurome lacquer paint with epoxidized linseed oil

Epoxidized linseed oilViscosity of mixtureb

mPasdotsNumber Degree of epoxidationa

ViscositymPasdots

1 ELO-6 64 514 23822 ELO-25 248 1099 38663 ELO-43 426 1831 42464 ELO-100 100 6017 69045 LO mdash 510 2983c

6 None mdash 4598aThe degree of epoxidation was calculated from 1H NMR spectrabEpoxidized linseed oils (ELO) were mixed in the kurome lacquer (KL) paint in the weight proportion of 1 10 and then viscosity was measured by the DV-II+viscometer at room temperaturecPhase separation occurred

Table 2 Polymerization of lacquer paints with epoxidized linseed oil ELO-6

Painta Polymerization timeb Polymerization film after 7 daysc

Number ELO-6 Viscosity TF HD Pencil Color scale Gloss 119879119892

Weight loss at 20 Residue at 600∘CmPasdots h hardness 119871lowast 119886lowast 119887lowast 60∘ ∘C ∘C

1 KL mdash 4598 44 86 HB 341 1300 441 885 901 406 082 KL ⃝ 2382 23 38 F 139 542 178 843 955 377 1773 HBL mdash 25476 12 20 F 095 061 056 762 1018 419 2964 HBL ⃝ 12841 11 20 F 059 038 947 869 1318 380 287aThe KL (kurome lacquer) and HBL (hybrid lacquer) paints with ELO-6 (64mol epoxidation) were prepared in the weight proportions as followsKL EOL-6 = 10 1 for number 2 KL hydrolyzed AATES = 10 1 for number 3 and KL hydrolyzed AATES ELO-6 = 10 1 025 for number 4 respectivelyViscosity was measured by the DV-II+ viscometer at room temperaturebPolymerization time was measured by touch-free (TF) polymerization state and hard (HD) polymerization state under 20ndash25∘C at 55ndash60 humiditycPencil hardness was recorded by the JIS-K 5400 drying recorder Color scale was measured by the BYK-Gardner according to the spectro-guide 450119871

lowast means brightness 119886lowast means +redminusgreen and 119887lowast means +yellowminusblue respectively The gloss (60∘) of polymerized film was obtained by the PG-1MglossmeterThe glass transition temperature (119879

119892) measurement was carried out with the RPT-3000W rigid-body pendulum-testing (RPT) machine

Temperature of weight loss at 20wt and residue at 600∘C were recorded by the DTG-60 thermoanalyser at the heating rate of 10∘C under N2 atmosphere

paint with ELOs in the weight proportion of 10 1 Theviscosity of the KL paint was 4598mPasdots (number 6) Linseedoil decreased its viscosity to 2983mPasdots (number 5) but aphase separation occurred at that proportion When ELO-6 with 64mol epoxidation was used the viscosity of theKL paint was found to decrease to 2382mPasdots (number 1)and no phase separation occurred at that proportion Theviscosity of the KL paint increased gradually as the degreeof epoxidation of the added linseed oil increased ELO-43(number 1) with 43mol epoxidation gave almost the sameviscosity (4246mPasdots) as that of the KL paint (4598mPasdots)as shown in number 6 and phase separation occurred Withproportions of ELOs higher than 10wt being added to theKL paint a phase separation of the KL paint occurred exceptwith ELO-6 Therefore ELO-6 was used as a reactive diluentfor both KL and HBL paints in this work

32 Polymerization of KL and HBL Paints with ELO-6Table 2 shows the results of polymerization of the KL andHBL paints with and without ELO-6 The polymerizationtimes of the paints and the color and gloss of the resultingpolymerized films were quantitatively compared to those

of the polymerized film of the KL paint The glass transi-tion temperature and thermostability were also comparedThe HBL paint that was obtained from the KL paint andhydrolyzed AATES in the weight proportion of 10 05 hadhigh viscosity of 25476mPasdots so that theHBL paint could notbe used directly as paintWhen 10wtof ELO-6was added tobothKL andHBL paints in the proportion of 1 10 (numbers 2and 4) the viscosities decreased by half of the original to 2382and 12841mPasdots respectively suggesting that ELO-6 workedeffectively as a diluent

The paint was coated on a glass plate at 76 120583m thick byusing a film applicator and then the polymerization timeand pencil hardness weremeasured after polymerizationTheoriginal KL paint (number 1) was polymerized to touch-free (TH) and hard (HD) polymerization states in 44 and86 h respectively as measured by the drying time recorderAddition of ELO-6 to the KL paint accelerated the poly-merization time to half in both touch-free (TH) and hard(HD) polymerization states (number 2) For the HBL paint(number 4) the polymerization time was the same whetheror not ELO-6 was added because the polymerization rate oftheHBL paint was originally fast but the viscosity of theHBL


(a) (b)

(c) (d)

Figure 1 Polymerized films of the KL and HBL paints (a) KL paint (b) KL paint with ELO-6 at 10 1 by weight (c) HBL paint and (d) HBLpaint with ELO-6 at 10 1 by weight

paint without ELO-6 was too high (number 3) These resultsindicate that ELO-6 increased the polymerizability of bothKL and HBL paints and decreased the viscosity After 7 daysthe pencil hardness of the polymerized films (numbers 2ndash4)reached F

The color scale gloss and thermal properties of thepolymerized films were also measured and are shown inTable 2 The color scale was evaluated quantitatively by thebrightness (119871lowast) red-green (119886lowast) and yellow-blue (119887lowast) propor-tions respectively using the BYK-Gardner apparatus Largernumbers mean stronger proportions of brightness red andyellow respectively Figure 1 shows photos of polymerizedfilms of the KL and HBL paints in which Figure 1(a) is thepolymerized film of the KL paint Figure 1(b) is the KL paintwith ELO-6 in the proportion by weight of 10 1 Figure 1(c)is the HBL paint and Figure 1(d) is the HBL paint with ELO-6 in the proportion by weight of 10 1 For the KL paint(number 1 in Table 1) the values of color scale were relativelylarge and the polymerized film seems to be light brownwith a little red as shown in Figure 1(a) For the HBL paint(number 3) the values were smaller and the polymerizationfilm showed a black color (Figure 1(c)) Addition of ELO-6 made the color slightly deeper as shown in Figures 1(b)and 1(d) respectively The surface of the polymerized films(numbers 2ndash4) remained glossy because they had almost thesame gloss values as the film of the KL paint (number 1)

The glass transition temperature (119879119892) of the films was

measured by the rigid-body pendulum-testing apparatus

99

94

100

80

60

40

20

00 2 31 4 5 6 7

Polymerization time (day)

Wei

ght a

fter a

ceto

ne ex

trac

tion

(wt

)

A

B

C

HBL + ELO-6KL + ELO-6KL

ABC

Figure 2 Extraction of polymerized film by acetone After 7 days ofpolymerization the weight of the film of the HBL paint with ELO-6in the weight proportion of 10 1 remained atmore than 99wt afterextraction with acetone suggesting that the HBL paint with ELO-6was completely copolymerized


8 6 4 2 0(ppm)

OHOH

Alkene

(a)

8 6 4 2 0(ppm)

OO O

OO

OO

MethyleneAlkeneCH2

CH2

CH3

(b)

Figure 3 500MHz 1HNMR spectra of acetone extracts from polymerization films after (a) 2 h and (b) 24 h polymerization respectivelyThepolymerization of the KL paint was carried out with ELO-6 in the weight proportion of 10 1 The spectra were obtained in CDCl

3

as solventat 30∘C

and the temperature of the loss of 20 weight and residualweights at 600∘Cwere analyzed by theDTG thermal analyzerThe film of the HBL paint with ELO-6 (number 4) hadthe highest 119879

119892of 1318∘C and 20 of the weight was lost

at 377∘ (number 2) and 380∘C (number 4) We found thatthe HBL films with and without ELO-6 showed the highestthermal stability and the residues at 600∘C still remainedat 296 and 287 of the feed respectively One of thereasons why the thermal stability increased was assumed tobe that the complex cross-linking which occurred radicallybetween urushiol the amino silane coupling reagent epoxygroup and unsaturated double bonds of side-chains in ELO-6 by the autooxidation by air in the second stage of lacquerpolymerization The polymerization films gave no acetoneextracts as described below

33 Estimated Polymerization Mechanism To elucidate thepolymerization mechanism of the KL and HBL paints withELO-6 acetone extraction of the resulting films was per-formed 2 h and 24 h after coating on the glass plate Figure 2shows the weights of polymerization films after acetoneextraction The films of the KL paint with and without ELO-6 had weight loss of 6 No weight loss of the film ofthe HBL paint with ELO-6 was observed The structure ofthe acetone extracts from the polymerized film of the KLpaint with ELO-6 was analyzed by the NMR measurementas shown in Figure 3 After 2 h polymerization urushiol wasthe main extract and small signals due to ELO-6 appeared(Figure 3(a)) however after 24 h urushiol was completelypolymerized and only ELO-6 was detected from the filmof the KL paint with ELO-6 (Figure 3(b)) Polymerizationof urushiol proceeds by two reaction stages the first stageis the reaction by laccase to obtain urushiol oligomers andthen in the second stage autooxidation by air occurred toafford cross-linked polymers Based on the polymerizationtime of the KL paint with ELO-6 the double bonds ofELO-6-amino silane reagent-urushiol complex 2 as shownin Scheme 1 also reacted with urushiol double bonds inthe second-stage polymerization to give cross-linked lacquerpolymers composed of urushiol amino silane reagent andlinseed oil On the other hand no extractswere obtained fromthe HBL paint with ELO-6 after 2 h and 24 h polymerization

indicating that ELO-6 reacted with the HBL paint to give acopolymerized film that consisted of HBL and ELO-6 units

Scheme 1 illustrates the proposed polymerization mech-anism of the HBL paint with ELO-6 Based on the recentresults on the polymerization of the HBL paint [11] thealcoholysis reaction of the amino silane reagent 119873-(2-aminoethyl)-3-aminopropyl trialkylsilane with a hydroxylgroup of urushiol occurred rapidly to give hybrid product1 and then the next urushiol continuously reacted with1 to give hybrid oligomers At the same time enzymaticpolymerization of urushiol by laccase and the subsequentautooxidation by air formed cross-linked polymerized filmin shorter time than the polymerization of the original KLpaint On the other hand the amino group of hybrid product1 also reacted with the epoxy group of ELO-6 to produceproduct 2 by a covalent bond which was polymerized inthe lacquer emulsion containing urushiol oligomers 2 by theautooxidation by air to give the cross-linked polymerizedfilms Therefore no acetone extracts were obtained from theHBL film with ELO-6 as shown in Figure 2

4 Conclusion

The epoxidized linseed oil ELO-6 with 64mol epoxidationwas found to work effectively as a reactive diluent in theHBL paint matrix The viscosity and polymerization time ofthe HBL paint with ELO-6 decreased to half compared tothose of the original HBL paint and polymerized films withpencil hardness of F were obtainedThe surface was almost asglossy as that of the filmpolymerized by the original KL paintThe polymerization mechanism was shown by the NMRmeasurements of the acetone extracts of the polymerizedfilms of the KL andHBL paints with ELO-6 after 2 h and 24 hsuggesting that the HBL paint reacted quickly with ELO-6to give a polymerized film with hard and glossy surface Onthe other hand the reaction of the KL paint with ELO-6 wasslow These results indicate that the amino group of the HBLpaint reacted rapidly with the epoxy group of ELO-6 and thenthe autooxidation by air occurred to produce the cross-linkedpolymerized film Major difference of current and otherpapers is that our method gave both short polymerizationtime of urushiol and glossy polymerized surface of oriental


Urushiol

OHOH

Enzymaticpolymerization

Laccase

ELO-6

OO O

OO

OO

Autooxidation

Polymerization

OO

OO

OO OHHN

N

OHO

HSi OO

(2)

HNSiO

O

O

R

R

R HybridizationO

OH

HNSiO

O

or urushiol

(1)

R = H or oligomer of this compound

R998400

R998400

R998400

R998400

NH2

NH2

R998400= H oligomer of this compound

Scheme 1 Proposed polymerizationmechanism ofHBL paint with the epoxidized linseed oil ELO-6The proportions of amino silane reagentand ELO-6 were 25 and 10mol of the KL paint respectively

lacquer by addition of alkoxy aminosilane compounds andreactive epoxidized linseed oil Further studies to elucidatethe polymerization mechanism and development of a newlacquer material are now under investigation

Conflict of Interests

The authors declare that there is no conflict of interestsregarding to the publication of this paper

Acknowledgments

The authors are sincerely grateful to Professor T Miyakoshiand Dr R Lu of Meiji University for many discussions andhelp in this workThis work was partly supported by the Aca-demic Frontier Project for Private Universities a matchingfund subsidy from MEXT (2007ndash2011) the New Energy and

Industrial Technology Development Organization (NEDO)of Japan Research Project Grant B by Institute of Science andTechnology Meiji University and Research Project Grant forYouth Meiji University

References

[1] J Kumanotani ldquoUrushi (oriental lacquer)mdasha natural aestheticdurable and future-promising coatingrdquo Progress in OrganicCoatings vol 26 no 2ndash4 pp 163ndash195 1995

[2] J Kumanotani ldquoEnzyme catalyzed durable and authentic ori-ental lacquer a natural microgel-printable coating by polysac-charide-glycoprotein-phenolic lipid complexesrdquo Progress inOrganic Coatings vol 34 no 1ndash4 pp 135ndash146 1997

[3] O Vogl ldquoOriental lacquer poison ivy and drying oilsrdquo Journalof Polymer Science Part A Polymer Chemistry vol 38 no 24pp 4327ndash4335 2000


[4] B Reinhammar ldquoPurification and properties of laccase andstellacyanin from Rhus verniciferardquo Biochimistry and BiophysicsActa vol 205 no 1 pp 35ndash47 1970

[5] R Oshima Y Yamauchi C Watanabe and J KumanotanildquoEnzymic oxidative coupling of urushiol in sap of the lac treeRhus verniciferardquo Journal of Organic Chemistry vol 50 no 15pp 2613ndash2621 1985

[6] H W-S Chan D T Coxon K E Peers and K R PriceldquoOxidative reactions of unsaturated lipidsrdquo Food Chemistry vol9 no 1-2 pp 21ndash34 1982

[7] N A Porter S E Caldwell and K A Mills ldquoMechanisms offree radical oxidation of unsaturated lipidsrdquo Lipids vol 30 no4 pp 277ndash290 1995

[8] R Lu S Harigaya T Ishimura K Nagase and T MiyakoshildquoDevelopment of a fast drying lacquer based on raw lacquersaprdquo Progress in Organic Coatings vol 51 no 3 pp 238ndash2432004

[9] R Lu T Ishimura K Tsutida T Honda and T MiyakoshildquoDevelopment of a fast drying hybrid lacquer in a low-relative-humidity environment based on kurome lacquer saprdquo Journalof Applied Polymer Science vol 98 no 3 pp 1055ndash1061 2005

[10] I Takahisa L Rong and M Tetsuo ldquoStudies on the reactionmechanism between urushiol and organic silanerdquo Progress inOrganic Coatings vol 55 no 1 pp 66ndash69 2006

[11] T Ishimura R Lu K Yamasaki and T Miyakoshi ldquoEffectsof hybridization of lacquer sap with organic silane on dryingpropertiesrdquo Progress in Organic Coatings vol 62 no 2 pp 193ndash198 2008

[12] T Ishimura R Lu K Yamasaki and T Miyakoshi ldquoDevel-opment of an eco-friendly hybrid lacquer based on kuromelacquer saprdquo Progress in Organic Coatings vol 69 no 1 pp 12ndash15 2010

[13] V Pitthard S Wei S Miklin-Kniefacz S Stanek M Griesserand M Schreiner ldquoScientific investigations of antique lacquersfrom a 17th-century Japanese ornamental cabinetrdquo Archaeome-try vol 52 no 6 pp 1044ndash1056 2010

[14] S Wei V Pintus V Pitthard M Schreiner and G SongldquoAnalytical characterization of lacquer objects excavated froma Chu tomb in Chinardquo Journal of Archaeological Science vol 38no 10 pp 2667ndash2674 2011

[15] J T P Derksen F P Cuperus and P Kolster ldquoPaints and coat-ings from renewable resourcesrdquo Industrial Crops and Productsvol 3 no 4 pp 225ndash236 1995

[16] J T P Derksen F P Cuperus and P Kolster ldquoRenewableresources in coatings technology a reviewrdquo Progress in OrganicCoatings vol 27 no 1ndash4 pp 45ndash53 1996

[17] W J Muizebelt J C Hubert M W F Nielen R P Klaasenand K H Zabel ldquoCrosslink mechanisms of high-solids alkydresins in the presence of reactive diluentsrdquo Progress in OrganicCoatings vol 40 no 1ndash4 pp 121ndash130 2000

[18] J Samuelsson P-E Sundell and M Johansson ldquoSynthesisand polymerization of a radiation curable hyperbranched resinbased on epoxy functional fatty acidsrdquo Progress in OrganicCoatings vol 50 no 3 pp 193ndash198 2004

[19] K Johansson andM Johansson ldquoFatty acidmethyl ester as reac-tive diluent in thermally cured solvent-borne coil-coatingsmdashthe effect of fatty acid pattern on the curing performance andfinal propertiesrdquo Progress in Organic Coatings vol 63 no 2 pp155ndash159 2008

[20] M A R Meier J O Metzger and U S Schubert ldquoPlant oilrenewable resources as green alternatives in polymer sciencerdquoChemical Society Reviews vol 36 no 11 pp 1788ndash1802 2007

[21] Y Ishii K Yamawaki T Ura H Yamada T Yoshida and MOgawa ldquoHydrogen peroxide oxidation catalyzed by heteropolyacids combined with cetylpyridinium chloride epoxidationof olefins and allylic alcohols ketonization of alcohols anddiols and oxidative cleavage of 12-diols and olefinsrdquo Journal ofOrganic Chemistry vol 53 no 15 pp 3587ndash3593 1988

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with unsaturated side-chains [8] Therefore a long time isnecessary to complete polymerization

Recently we developed a hybrid lacquer (HBL) paint toimprove the polymerizability of kurome lacquer (KL) paint[9]When an amine-functionalized organic silane compound(amino silane regent)119873-(2-aminoethyl)-3-aminopropyl tri-methoxysilane (AATMS)119873-(2-aminoethyl)-3-aminopropyltriethoxysilane (AATES) or119873-(2-aminoethyl)-3-aminopro-pyl methyl dimethoxysilane (AAMDMS) was added tothe KL paint the polymerization time was shortened to6 h in humidity below 55 and temperature at 20∘C [1011] Therefore the HBL paint is expected to increase theproduction of lacquer wear However the HBL paint hadhigher viscosity than the original KL paint due to the increaseof polymerized and polycondensed compounds in the first-stage polymerization [12] Viscosity of lacquer paint ingeneral decreases the handling properties compared to thatof other coating methods of spraying dipping and paintingby brush

Plant oil linseed oil has been often used as a diluent todecrease the viscosity of lacquer paint and to increase thegloss of the resulting polymerized lacquer film [13 14] Afterpolymerization however linseed oil sometimes oozes out ofthe polymerized film Thus improvements in polymerizabil-ity are required for the general use of lacquer paints andmaterials in the future In this paper we report a new reactivediluent prepared by the epoxidation of linseed oil [15ndash21] Wefound that the epoxidized linseed oil ELO-6 with 64molepoxidation worked effectively in polymerization of bothHBL and natural KL paints without any volatile componentsThe drying properties and hardness after polymerization oftheHBL andKLpaintswith epoxidized linseed oils as reactivediluents are reported The polymerization mechanism ofHBL and KL paints with the epoxidized linseed oil wasevaluated by NMR measurements of acetone extracts fromthe corresponding polymerization films

2 Materials and Methods

21 Materials Kurome lacquer (KL) paint was purchasedfrom Dohichu Shoten (Osaka Japan) The KL paint usedhere was composed of urushiol (896) water (41)and acetone-insoluble compounds (63) such as polysac-charides glycoprotein and laccase 119873-(2-aminoethyl)-3-aminopropyl triethoxysilane (AATES) was obtained fromShin-Etsu Silicone Co Ltd (Tokyo Japan) The linseed oil(LO) used was reagent grade

22 Measurements The drying of lacquer paints was evalu-ated by using drying time recorder (Taiyu Equipment OsakaJapan) according to the JIS-K-5400 standards The hardnessof polymerized films was determined using mechanical pen-cil hardness tester (Yoshimitsu Seiki Tokyo Japan) accordingto the JIS-K-5600 standards Viscosity was measured byBrookfield cone-plate type viscometer DV-II+The 500MHz1H NMR spectrum in CDCl

3as a solvent at 25∘C was

obtained by using JEOL JNM-ECA500 spectrometer withtetramethylsilane as a reference (000 ppm) Color scales ofpolymerization films were determined by the color standard

(119871lowast119886lowast119887lowast system) using BYK-Gardner Gmbh colorimeter(Germany) Spectroguide 450 was usedThe symbols 119871lowast 119886lowastand 119887lowast mean brightness and the ratios of red (+) to green (minus)and yellow (+) to blue (minus) respectively The gloss of the poly-merized filmswasmeasured by a glossmeter PG-1M (NipponDenshoku Japan) Thermogravimetric analysis (TGA) of thepolymerized films was performed using Shimadzu DTG-60 thermoanalyser at the heating rate of 10∘Cmin underN2atmosphere The glass transition temperature (tan 120575)

of polymerization films was recorded using a rigid-bodypendulum-testing machine RPT-3000W (AampD Co LtdJapan)

23 Synthesis of Epoxidized Linseed Oil [21] A typical proce-dure for the epoxidation of linseed oil ELO-6 with 64molepoxidation is as follows To a solution of linseed oil (440 g500mmol) in CHCl

3(150mL) were added 06 g of phos-

photungstic acid (002mmol) and 0215 g of cetylpyridiniumchloride (006mmol) After 30 hydrogen peroxide solution(567 g 500mmol) was added the mixture was refluxedfor 6 hours with vigorous stirring After cooling to roomtemperature the separated CHCl

3layer was washed by

distilled water twice and then dried over anhydrous sodiumsulfate After filtration and evaporation to remove sodiumsulfate and CHCl

3 respectively epoxidized linseed oil (ELO-

6) (420 g) with 64mol epoxidation was obtained in 95yield The epoxidized linseed oil was used without furtherpurification

24 Polymerization of Hybrid Lacquer Paint with ELO-6To the KL paint (100 g) was added 10 g of epoxidizedlinseed oil (ELO-6) as a reactive diluent The mixture wasstirred for 30min at room temperature and then 05 g ofhydrolyzed AATES that had been prepared by addition ofwater was added The mixture was further stirred for 30minand then coated at 76 120583m thickness on a glass plate byusing a film applicator The lacquer-coated glass plate wasmaintained at 25∘C under 60 humidity for the enzymaticand autooxidative polymerization

25 Extraction of Polymerization Films by Acetone To inves-tigate the polymerizability of epoxidized linseed oil (ELO-6) the polymerization films of the KL paint with ELO-6and AATES after polymerization for 2 h 24 h and 168 h (7days) respectively were extracted by acetone The extractswere identified by the 1H NMR measurements The resultsare shown in Figure 3

3 Results and Discussion

31 Synthesis of Epoxidized Linseed Oils In general a smallamount of oil of linseed (Linum usitatissimum) is usedas a diluent of KL paint to decrease the viscosity andimprove the gloss of the surface of the polymerized filmHowever linseed oil often oozes out of the polymerizationfilm Therefore epoxidized linseed oils as a new reactivediluent were synthesized by the epoxidation of linseed oilwith hydrogen peroxide (H

2O2) and heteropoly acid-CPC

system as a catalyst Table 1 shows the viscosity of the KL





ViscositymPasdots
















(a) (b)

(c) (d)






99

94

100

80

60

40

20

00 2 31 4 5 6 7


Wei

ght a

fter a

ceto

ne ex

trac

tion

(wt

)

A

B

C


ABC



8 6 4 2 0(ppm)

OHOH

Alkene

(a)

8 6 4 2 0(ppm)

OO O

OO

OO

MethyleneAlkeneCH2

CH2

CH3

(b)


3

as solventat 30∘C







4 Conclusion



Urushiol

OHOH


Laccase

ELO-6

OO O

OO

OO

Autooxidation

Polymerization

OO

OO

OO OHHN

N

OHO

HSi OO

(2)

HNSiO

O

O

R

R

R HybridizationO

OH

HNSiO

O

or urushiol

(1)


R998400

R998400

R998400

R998400

NH2

NH2






Acknowledgments



References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







ViscositymPasdots
















(a) (b)

(c) (d)






99

94

100

80

60

40

20

00 2 31 4 5 6 7


Wei

ght a

fter a

ceto

ne ex

trac

tion

(wt

)

A

B

C


ABC



8 6 4 2 0(ppm)

OHOH

Alkene

(a)

8 6 4 2 0(ppm)

OO O

OO

OO

MethyleneAlkeneCH2

CH2

CH3

(b)


3

as solventat 30∘C







4 Conclusion



Urushiol

OHOH


Laccase

ELO-6

OO O

OO

OO

Autooxidation

Polymerization

OO

OO

OO OHHN

N

OHO

HSi OO

(2)

HNSiO

O

O

R

R

R HybridizationO

OH

HNSiO

O

or urushiol

(1)


R998400

R998400

R998400

R998400

NH2

NH2






Acknowledgments



References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)






99

94

100

80

60

40

20

00 2 31 4 5 6 7


Wei

ght a

fter a

ceto

ne ex

trac

tion

(wt

)

A

B

C


ABC



8 6 4 2 0(ppm)

OHOH

Alkene

(a)

8 6 4 2 0(ppm)

OO O

OO

OO

MethyleneAlkeneCH2

CH2

CH3

(b)


3

as solventat 30∘C







4 Conclusion



Urushiol

OHOH


Laccase

ELO-6

OO O

OO

OO

Autooxidation

Polymerization

OO

OO

OO OHHN

N

OHO

HSi OO

(2)

HNSiO

O

O

R

R

R HybridizationO

OH

HNSiO

O

or urushiol

(1)


R998400

R998400

R998400

R998400

NH2

NH2






Acknowledgments



References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




8 6 4 2 0(ppm)

OHOH

Alkene

(a)

8 6 4 2 0(ppm)

OO O

OO

OO

MethyleneAlkeneCH2

CH2

CH3

(b)


3

as solventat 30∘C







4 Conclusion



Urushiol

OHOH


Laccase

ELO-6

OO O

OO

OO

Autooxidation

Polymerization

OO

OO

OO OHHN

N

OHO

HSi OO

(2)

HNSiO

O

O

R

R

R HybridizationO

OH

HNSiO

O

or urushiol

(1)


R998400

R998400

R998400

R998400

NH2

NH2






Acknowledgments



References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Urushiol

OHOH


Laccase

ELO-6

OO O

OO

OO

Autooxidation

Polymerization

OO

OO

OO OHHN

N

OHO

HSi OO

(2)

HNSiO

O

O

R

R

R HybridizationO

OH

HNSiO

O

or urushiol

(1)


R998400

R998400

R998400

R998400

NH2

NH2






Acknowledgments



References






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article polymerization of oriental lacquer...

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