synthesis of polyether polyols with epoxidized soy bean oil

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Progress in Organic Coatings xxx (2013) xxx– xxx

Contents lists available at SciVerse ScienceDirect

Progress in Organic Coatings

jou rn al hom ep age: www.elsev ier .com/ locate /porgcoat

ynthesis of polyether polyols with epoxidized soy bean oil

inda C. Bailoskya, Lynn M. Bendera, Daniel Bodea, Riaz A. Choudheryb, Gary P. Crauna,∗,enneth J. Gardnera, Candice R. Michalskia, Jude T. Rademachera,uy J. Stellaa, David J. Telforda

AkzoNobel Packaging Coatings, 16651 Sprague Road, Strongsville, OH 44136, USAAkzoNobel Decorative Paints, Wexham Road, Slough, Berks SL2 5DS, England, United Kingdom

a r t i c l e i n f o

rticle history:vailable online xxx

eywords:poxidized soy bean oilolyether polyolriflic acidcrylic graftolvent borneater borne

a b s t r a c t

Epoxidized soy bean oil (ESBO) polyether polyols have been prepared and evaluated as potential bio-renewable replacements for bisphenol A based epoxy coatings. Zinc triflate was found to be more efficientin catalyzing the ESBO hydroxyl reaction than methanesulfonic acid or boron trifluoride etherate. Withan excess of n-butanol, ESBO epoxide groups ring open to give the expected polyether polyol, but asthe n-butanol concentration is reduced, dimers, trimers, and higher molecular weight analogs of thetriglycerides appear. Weight average molecular weight can be increased in a controlled fashion to over10,000 Da by using trimethylolpropane (TMP) in place of n-butanol. The addition of solvent reducesmolecular weight of the polyether polyol, at an equivalent TMP level while still allowing good reactioncontrol. These polyether polyols can be cured with phenolic resins, but solvent and blush resistance,adhesion, and wedge bend flexibility are inferior to a commercial bisphenol A epoxy control.

ESBO polyether polyols were then grafted with an acrylic monomer mix that included methacrylicacid using initiators with high grafting efficiencies. Neutralization with a base allowed the formation of
stable aqueous dispersions. However, use of an initiator with a low grafting efficiency under the sameconditions did not produce a stable aqueous dispersion. A simple blend of a pre-formed acrylic with theESBO polyether polyol likewise did not form a stable dispersion. Solvent borne and water borne ESBOpolyether polyol acrylic grafted co-polymers were cured with phenolic, benzoguanamine and melaminecrosslinkers. Films were comparable to a commercial BPA epoxy control having excellent solvent andblush resistance, good adhesion, and good flexibility.
. Introduction

The replacement of petroleum-derived chemicals with bio-enewable chemicals offers significant advantages. Bio-renewablehemicals are generally lower in environmental impact, and theirse benefits the agricultural business. As petroleum supplies dwin-le, switching to bio-renewable materials will become increasinglyttractive from an economic standpoint [1]. Soy bean oil is a lowost vegetable oil produced commercially in large quantities. It isydrophobic, relatively stable to hydrolysis, and a liquid at roomemperature. Its double bonds are not reactive as such, but theyan be converted to epoxy groups. Epoxidized soy bean oil (ESBO)s generally produced by oxidation with hydrogen peroxide and

Please cite this article in press as: L.C. Bailosky, et al., Synthesis of polyehttp://dx.doi.org/10.1016/j.porgcoat.2013.05.005

cetic or formic acid. ESBO can then be converted into polyols bying opening reactions of the epoxy groups [2–4].

∗ Corresponding author. Tel.: +1 440 297 5237; fax: +1 440 297 5233.E-mail address: [email protected] (G.P. Craun).

300-9440/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.porgcoat.2013.05.005

© 2013 Elsevier B.V. All rights reserved.

We undertook this work to determine whether or not poly-mers made from ESBO could function as suitable replacementsfor bisphenol A (BPA) epoxy polymers in the food and beveragecan coatings industry. Food and beverage can coatings have tomeet a very demanding list of requirements. In addition to havinggood adhesion to various metals, they must be flexible and tough.Because cans are often heated to 100–140 ◦C after filling with foodsand beverages, coatings must be resistant to attack in these aqueousenvironments [5].

Soy bean oil is a triglyceride which has an average compo-sition of 15% stearic acid (C18:0), 25% oleic acid (C18:1), 51%linoleic acid (C18:2), and 9% linolenic acid (C18:3) [6]. Oleic, linoleic,and linolenic acids all have cis-double bonds, with the first beingbetween the 9th and 10th carbon, the second being between the12th and 13th carbon, and the third being between the 15th and the16th carbon [7]. Soy bean oil, when epoxidized, can be represented

ther polyols with epoxidized soy bean oil, Prog. Org. Coat. (2013),

by the structure in Fig. 1. Soy bean oil, and hence ESBO, has a randomdistribution of fatty acids. The triglycerides, therefore, can haveany number of double bonds from zero (if composed of three satu-rated stearic acids) to nine (if composed of three triply-unsaturated

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O

OO O

OO

O

O

OO O

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OOH

OH OH

OH

OP

O

O

O

O

OOH

OOH OH

OH OH

2.1. Materials

Fig. 1. Representative ESBO structure.

inolenic acids). The actual distribution of double bonds per triglyc-ride on a weight per cent basis is given in Fig. 2 [7,8].

Reactions of epoxides with aliphatic hydroxyls have been welltudied. Liao and Bertram advanced the diglycidyl ether of BPAith 1,4-butanediol in a 2:1 mole ratio to make an epoxy func-

ional polymer using trimethylsilyl-trifluoromethanesulfonate as catalyst in anhydrous diglyme [9]. Koleske in a similar fashionade a hydroxyl functional polymer by reacting a molar excess of a

ihydroxy polytetramethyleneoxide with a cycloaliphatic diepox-de using diethylammonium triflate as the catalyst [10]. Fujiokat al. reacted glycidylmethacrylate with TMP under mild condi-ions (60 ◦C) with boron tetrafluoride ethyl etherate to make aadiation curable oligomer [11]. Huemmer and Edison used boronrifluoride etherate to make a radiation curable oligomer with-hydroxyethylacrylate and ESBO [12]. Their patent teaches thatseful initiators for the aliphatic hydroxyl reaction with epoxidesre strong Lewis acids. A cationic ring opening reaction of thepoxide with the hydroxyl proceeds rapidly, even at ambient tem-eratures.

Several approaches have been used to make polyols from ESBOy ring opening reactions involving the epoxide groups. Zhong et al.rst phosphorylated ESBO with super phosphoric acid at 35 ◦C, andhen ring opened the remaining epoxy groups of the ESBO withater under acidic conditions to make a phosphate ester polyol [3].

ig. 3 is a representative structure of this phosphate ester polyol.ydroxyl groups formed by the ring opening reaction of epox-

des with water are all secondary, and are all located internallyn the fatty acid chains. Petrovic et al. used methanol to ring openSBO epoxide groups [4]. Fig. 4 is a representative structure of theesulting polyol. When an alcohol is used to make a polyol fromSBO one ether and one secondary hydroxyl is produced from eachpoxide. Petrovic and coworkers produced laminates with goodroperties from ESBO polyols, di-isocyantes, and natural and syn-hetic fibers. Guo et al. used polyols made from ESBO and methanolith di-isocyantes to make rigid polyurethane foams [1]. In a sec-

nd study Guo et al. evaluated several acids as catalysts for the ringpening of the epoxide groups in ESBO with methanol [2]. They


ound that HBF4 produced polyols with a higher OH content, andower viscosity than perchloric acid, p-toluenesulfonic acid, sulfu-ic acid, or formic acid. Dahlke et al. studied the ring opening of the

Fig. 2. Distribution of C C functionality in ESBO on a wt% basis.

OHHO

Fig. 3. ESBO phosphate polyol.

epoxide groups in ESBO with several hydrogen donors, includingwater, alcohols, diols, and amines [13]. They noted that depend-ing on the molar proportion of the hydrogen donor, intermolecularether formation could occur as a side reaction. Guo et al. also notedthe occurrence of side reactions during the ring-opening of ESBOepoxide groups [14]. In the presence of water and phosphoric acidoligomerization due to oxirane–oxirane and/or oxirane–hydroxylreactions can take place. Three ring-opening pathways were pro-posed (see Fig. 5). Of the three pathways, both the polyether alcoholand the alcohol ether reaction could lead to oligomerization. In thepolyether alcohol reaction, the hydroxyl formed by the ring open-ing of an epoxide group in one ESBO molecule could ring openthe epoxide group in a second ESBO molecule to form a triglyc-eride dimer. Subsequent reactions of this type could then lead tohigher molecular weight analogs. Also, if a diol or triol was reactedwith ESBO, as in the alcohol ether pathway, a remaining hydroxylgroup from the diol or triol could then react with a second ESBOmolecule to form a triglyceride dimer, and then higher molecularweight analogs.

This oligomerization of ESBO to form higher molecular weightpolyether polyols presented itself to us as a potential route to syn-thesize materials that could be used in food and beverage cancoatings. The first part of this paper summarizes our efforts toprepare ESBO polyol polyether oligomers, and then formulate theminto can coatings. The second part of this paper summarizes ourefforts to graft the ESBO polyether polyols with acrylic monomers,and then formulate these graft co-polymers into can coatings.

2. Experimental


All materials were used as supplied by their manufacturers.

O

OOCH3 OCH3

OH OH

O

O

OH

OCH3

O

O

OH OH

OCH3 OCH3

Fig. 4. ESBO methanol polyether polyol.




L.C. Bailosky et al. / Progress in Organic Coatings xxx (2013) xxx– xxx 3

CH CHO

H2O H+

CH C

O

+

H.

HOO

H2O

CH CH

OH

OH

Diol

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O

CH CH

O

Poly ether alcohol

CH CH

O

OH

Alcohol ether

ing op

2

2p

pmAsbpo

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e1bamtviwa3

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Fig. 5. ESBO epoxy r

.2. Synthesis

.2.1. Example procedure for the synthesis of an ESBO polyetherolyol

Prepare a 1 l round bottom flask with a 5 cm stainless steeladdle mechanical stirrer and stir bearing, nitrogen inlet, ther-ocouple/temperature controller, heating mantel, and condenser.dd 100 g ESBO, 23 g propylene glycol (PG), and 0.26 g of a 10%olution of zinc triflate in n-butanol to the flask under a nitrogenlanket. Heat the reaction mixture to 150 ◦C, and hold for 2 h. Sam-le, and measure the oxirane concentration. Cool if conversion isver 99%.

.2.2. Example procedure for the synthesis of an acrylic graftedSBO polyether polyol

To the above ESBO polyether polyol add 24 g n-butanol and 17 gthylene glycol monobutyl ether (butyl cellosolve, BC), and heat to00 ◦C under nitrogen. Mix 35 g methylmethacrylate (MMA), 35 gutylmethacrylate (BMA), 18 g methacrylic acid (MAA), 3.1 g BC,nd 3.1 g benzoyl peroxide (BPO). Feed the monomer and peroxideixture into the flask over 2 h. Hold 30 min at 100 ◦C. Add 0.66 g

-butyl peroctoate (TBPO) and 0.66 g BC three times at 30 min inter-als. Cool to 85 ◦C and add 14.6 g dimethylethanolamine (DMEA)n 26.5 g deionized water, stir 5 min, and then add 292 g deionized

ater over 15 min at 85 ◦C. The product has 25% polymer solids, and viscosity of 1200 mPAs (Brookfield Viscometer Model LVDL-1, at

rpm, #62 spindle, 25 ◦C).

.2.3. Coating preparationsCombine 32 g of the acrylic grafted ESBO polyether polyol with


.0 g Cymel 303 (hexamethoxymethyl melamine, Cytec Industries,nc.) and 6.0 g deionized water. Stir 1 h with a magnetic stirrer.raw down a film with a #7 wire wound bar on a 10 cm × 10 cmluminum panel (0.2 mm thickness). Bake in a direct gas fired

ening pathways [8].

oven 10 min at 190 ◦C. The baked film weight was measured as25 mg/cm2.

2.3. Methods

2.3.1. Polymer characterization2.3.1.1. Oxirane content (epoxy conversion). Prepare a solution of250 g tetraethyl ammoniuim bromide and 10 mg crystal violet indi-cator in 1000 ml glacial acetic acid. Add 10 ml of this solution to1.00 g of sample to be tested. Add 70 ml dichloromethane, andtitrate with 0.1 N perchloric acid (in glacial acetic acid) to the indi-cator end point (blue changes to green). Titrant ml × 10 = mequiv.epoxy (oxirane)/g sample.

2.3.1.2. Gel permeation chromatography (GPC). Polymer samples tobe tested were diluted to give about 0.5 g/100 ml THF. Sampleswere filtered and injected into a Waters Alliance GPC2000 withan elution rate of 1 ml/min THF using an infrared detector at 45 ◦C.Columns included a guard, two Polymer Labs mixed bed C’s anda Polymer Labs 100A. Polystyrene standards from 2,400,000 Da to300 Da provided calibration.

2.3.1.3. Polymer glass transitions (Tg). Baked coatings were scrapedoff Al panels with a razor blade. About 5 mg polymer was placed ina sealed Al differential scanning calorimeter (DSC) pan and placedin a TA Instruments Q1000 MDSC. Samples were heated from −90to 150 ◦C at 3 ◦C per min, cooled, and subjected to a second similarheating ramp. Modulation was used at 1 ◦C/min.

2.3.1.4. Particle size. Particle sizes in the 1 nm to 1 �m range were


obtained with Particle Sizing System’s NICOMP Model 370 Sub-micron Particle Sizer. Samples were prepared by diluting about 8drops sample in 10 ml distilled water that contained 1 drop Tri-ton X100 surfactant (Dow Chemical Co.). After being placed in an


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ARTICLEOC-3120; No. of Pages 8

L.C. Bailosky et al. / Progress in

ltrasonic bath for 1 min, a 2 ml sample was injected into the instru-ent’s auto-dilution system.Larger particle sizes were measured with Microtrac Inc.’s S3500.

bout 5 drops sample in 4 ml distilled water were added to theesting chamber (no ultrasonic mixing).

.3.2. Film properties

.3.2.1. Methyl ethyl ketone solvent rubs. Methylethyl ketone (MEK)ouble solvent rubs (MEKDR) were used as a measure of cure. Withroper ventilation a clean cotton cloth was wrapped around the

ndex finger of a solvent resistant gloved hand and soaked withEK. With about 2 kg force a baked film was rubbed quickly back

nd forth with 2 cm strokes 10 times (about 2 strokes per second).ilm condition was observed, the cloth was re-soaked with MEK,nd 10 more rubs were applied to the same section of the film. Thisrocess was continued until removal of the film was noted, or to00 MEKDR.

.3.2.2. Adhesion. A scribe was used to make a cross hatch pat-ern of scratches (through the film to the substrate) such that 25

mm × 2 mm patches of coating were created. Scotch Brand #610dhesive tape was applied firmly over the cross hatch section, andhen quickly removed. Adhesion was determined as a % of coatingn the cross hatch section remaining on the substrate.

.3.2.3. Pencil hardness. A set of mechanical pencils containingurquoise #2375 Eagle Drawing leads with hardness ranging fromB (soft) to 8H (very hard) is set out with the coated panel on aat surface with 400 grit abrasive paper. Starting with the H pencil,he graphite is drawn across the abrasive paper to create a flat endhich is perpendicular to the axis of the pencil. At a 60◦ angle from

he coating, the pencil is pushed across the coating for 1 cm withbout 1 kg force. If film is removed, the next softer pencil is thensed in the same manner, and if no film is removed, the next harderencil is then used in the same manner. Hardness is recorded as theardest pencil used that did not remove coating.

.3.2.4. Impact. Forward impact (coated side up), and reversempact (coated side down) is tested with 0.2 mm Al panels using

Gardner Coverall impact tester equipped with a 1.5 cm diam-ter hemispherical dart. After impact (1 kg dart is dropped from.2 m) the coating around the impact site is observed, and crackingr adhesion loss is noted.

.3.2.5. Wedge bend. A 100 mm × 100 mm coated panel ismoothly bent in half to give a 5 mm gap with the coatedide exposed. Using the Gardner Coverall impact tester, the 1 kgart is dropped from 0.6 m onto a 3.2 mm mandrel to give a wedgeend. The coating along the wedge bend is observed, and the mmf intact coating (not cracked or delaminated) is recorded as %assed.

.3.2.6. Blush. A coated panel is immersed 3 cm into a beaker ofistilled water, and the beaker is processed at 120 ◦C for 1 h in ateris model Ten Sixteen Plus autoclave. Immediately upon removalrom the water the film is observed and rated on a 0–10 scale, with: opaque, and 10: blush free (clear film is visually unaffected).rine blush testing is done with the same procedure using 2% NaCl

n distilled water as the brine solution.

. Results and discussion


.1. ESBO reactions with alcohols

A series of ESBO reactions with n-butanol or benzyl alcohol usinghree catalysts was first done to evaluate epoxy conversion. As

PRESSic Coatings xxx (2013) xxx– xxx

noted above, triflic acid salts were previously evaluated in epoxyhydroxyl reactions by Liao and Bertram and Koleske [9,10], boronetherates by Fujioka et al. and Huemmer and Edison [11,12], andsulfonic acids by Guo et al. [2]. At 115 ◦C with a 50:50 weight ratioof ESBO to n-butanol methanesulfonic acid (MSA) and boron triflu-oride etherate (BTFE) at a 0.5% weight ratio to reactants both gaveabout 50% conversion of the epoxy to the polyether polyol after3 h (see Table 1). Initial reactions with zinc triflate (Nacure A-218,King Industries) at 0.5% were so rapid, that the reaction temper-ature could not be controlled. Zinc triflate was reduced stepwise,until at 0.01% good reaction control was achieved while maintain-ing an epoxy conversion rate of 99% after 3 h. Reducing the zinctriflate concentration further to 0.0025% gave 87% conversion underthe same conditions. When the ESBO to alcohol weight ratio waschanged to 80/20, 0.0025% zinc triflate gave 50% conversion of theepoxy groups with n-butanol, but 99% conversion with benzyl alco-hol. The reaction rate of ESBO epoxy and alcohol hydroxyl groups isthus directly related to alcohol concentration. Benzyl alcohol gavea higher conversion than n-butanol under the same conditions, soalcohol structure also affects conversion. Lewis acid catalyst typehas a dramatic affect on conversion, with zinc triflate giving highepoxy conversion at concentrations that are more than an order ofmagnitude lower than MSA or BTFE.

The GPC trace of ESBO in Fig. 6 (curve a) is very narrow with a Mnof 1289 and a polydispersity (PDI) of 1.05. At 50% conversion withn-butanol (0.5% MSA catalyst, curve b), Mn climbs to 1531, and PDIto 1.13. At 99% conversion with n-butanol (0.01% zinc triflate, curvec) Mn climbs to 1623, and PDI to 1.24. Peak molecular weight whichis 1321 for ESBO increases to 1644 after full reaction with n-butanol(99% conversion). This rise corresponds almost exactly to the addi-tion of the expected 4.5 n-butyl ethers to ESBO. A second, highermolecular weight peak is becoming more noticeable in this series,and a higher molecular weight tail is forming. This shift to highermolecular weight continues when the n-butanol concentration isreduced (curve d). The higher molecular weight peaks are taken tobe ESBO polyol oligomers produced by epoxy hydroxyl reactionsbetween triglycerides. These results are in good agreement withDalke [13] and Guo et al. [14] who attributed the appearance ofthese oligomers to intermolecular ether formation. In an effort tofurther increase molecular weight we substituted TMP for all ofthe alcohol, and we then reduced its concentration in a stepwise


Slice Log MW

Fig. 6. GPC traces: ESBO and ESBO reaction products with alcohols. Curves a: ESBO,b: ESBO 50/50 (w/w) n-butanol 50% conversion, c: ESBO 50/50 (w/w) ratio 99%conversion, d: ESBO 80/20 (w/w) ratio n-butanol 99% conversion.





Table 1ESBO reactions with alcohol.

Run ESBO/ROHa Alcohol Catalyst Epoxy conversion

1 50/50 n-Butanol 0.5% methanesulfonic acid 56%2 50/50 n-Butanol 0.01% zinc triflate 99%3 50/50 n-Butanol 0.0025% zinc triflate 87%4 50/50 n-Butanol 0.5% boron trifluoride etherate 50%

3

rTht(ssTnwfttr

wathr(aaTc

pcii

FT

5 80/20 n-Butanol

6 80/20 Benzyl alcohol

a Weight ratio ESBO to alcohol.

.2. ESBO reactions with polyols

TMP was combined with ESBO at 42/58, 38/62, and 33/67 weightatios. These ratios correspond to 1.2/1, 1.0/1.0, and 0.8/1.0 molesMP per equivalent of epoxide, or 3.6/1.0, 3.0/1.0, and 2.4/1.0ydroxyl equivalents per epoxide equivalent respectively. The GPCraces of the reactions products with zinc triflate catalyst in Fig. 7curves a, b, and c, respectively) indicate that in addition to theharp monomer peak, which is taken to be ESBO/TMP polyol, sub-tantial amounts of higher molecular weight polymer is produced.he polyether polyol prepared with the 33/67 ratio was elastic inature, and appeared to be close to gelation. Its high moleculareight tail stretches up to over 1 million Daltons. The GPC trace

rom the 38/62 ratio is actually slightly lower in molecular weighthan what was measured for the 42/58 ratio, but this is likely due tohe fact that conversion in this case was only 93%, while the othereactions were carried to over 99% conversion.

A second series of TMP reactions with ESBO was done at an 80/20eight ratio of ESBO + TMP in methylamyl ketone (MAK). MAK was

ssumed to be non-functional under these reaction conditions. GPCraces of the polyether polyols in Fig. 8 again follow a trend, withigher molecular weights at lower TMP concentrations. ESBO/TMPatios in solvent, however, could be reduced to as low as 20/800.4 moles TMP per epoxide, curve c) without gelation. As notedbove, neat reactions of TMP with ESBO were approaching gelationt a 0.8/1.0 mole ratio. Dilution with MAK thus allows synthesis ofMP ESBO polyether polyol oligomers over a wider range of TMPoncentrations with good molecular weight control.

ESBO reactions with hydroxyl functional materials like TMP canroduce polyether polyols with a range of molecular weights in a


ontrolled fashion, neat and in solvent. Referring back to Fig. 5, its thought that ESBO reactions with alcohols and triols like TMPnvolve two pathways: (1) the epoxy self-condensation pathway

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5

dwt/d

(logM

)

(a)

(b)

(c)

Slice Log MW

ig. 7. GPC traces: ESBO reaction products with TMP. Curves a: 42/58 (w/w)MP/ESBO, b: 38/62 (w/w) TMP/ESBO, c: 33/67 TMP/ESBO.

0.0025% zinc triflate 50%0.0025% zinc triflate 99%

that produces a polyether alcohol, and (2) the epoxy reaction withthe alcohol (or triol) that produces an alcohol ether. Additionalwork with hydroxyl functional materials led us to focus on pro-pylene glycol (PG) as a co reactant with ESBO. PG was seen as anattractive material to use in food can coatings, because it is gener-ally regarded as safe for use in foods [15].

3.3. ESBO polyether polyol crosslinked films

A PG ESBO polyether polyol was prepared neat at a 20/80 weightratio as described above in Section 2.2.1 of this report. The productwas combined in different ratios with 2 phenolic crosslinkers, andcured at 200 ◦C for 12 min. Results as given in Table 2 indicate thatdegree of cure as measured by MEKDR is directly related to thelevel of the branched phenolic, Rutaphen 7700 (Hexion ChemicalCo.), but higher levels of this phenolic crosslinker adversely affectadhesion and wedge bend. Using only the linear phenolic, RS 199(Cytec Industries, Inc.), MEKDR is sacrificed, but blush and retortwere acceptable, and wedge bend was marginal at 24%. A muchbetter balance of properties was obtained with C-1, the proprietarycommercial BPA epoxy control. This level of performance (wedgebend flexibility less than 20% with good blush and adhesion with100 MEKDR) is required for commercial food can coatings. Theseresults led us to consider possible synthetic routes that could beused to modify ESBO polyether polyols and achieve a better balanceof properties in cured films.

3.4. Acrylic grafted ESBO polyether polyol co-polymers

BPA based epoxy polymers can be modified by grafting withacrylic monomers. If a sufficient level of carboxylic functional


acrylic monomer is used, the resulting acrylic grafted co-polymerscan be inverted into water after neutralization with tertiary amineor other suitable base. It is thought that the CH2 groups adjacentto ether groups in the BPA epoxy polymers are liable to hydrogen

Sli ce Log MW

(a)(b)

(c)

3.0 3.5 4.0 4.5 5.0 5.5 6.0

dwt/d

(logM

)

Fig. 8. GPC traces: ESBO reaction products with TMP in solvent. Curves a: 42/58(w/w) TMP/ESBO, b: 33/67 (w/w) TPM/ESBO, c: 20/80 (w/w) TMP/ESBO.




6 L.C. Bailosky et al. / Progress in Organic Coatings xxx (2013) xxx– xxx

Table 2ESBO polyether polyol baked films.

Run ESBO/PG Phenolic #1 Phenolic #2 MEK DR Blush Adhesion Wedge

1 50% 50% 0% 12 0 100% 24%2 30% 55% 15% 100 1 25% 35%3 50% 40% 10% 47 3 95% 20%C-1 na na na 100 0 100% 4%

Phenolic #1: linear phenolic RS 199 (Cytec Industries Inc.), phenolic #2: branched phenolic Rutaphen 7700LB (Hexion Chemical Co.), blush in water with 0: none, 5: opaque,wedge bend as % failure. Films baked on tin free steel panels at 200 ◦C for 12 min. Film thickness: 2 �m. C-1 is a proprietary commercial epoxy control coatings. Na: notapplicable.

Table 3Acrylic grafting initiator study.

Run Initiator Grafting efficiencya Grafting temperature Inverted sample Particle size

1 1.5% TBP 49 130 ◦C Stable na2 2.2% TBPO 16 96 ◦C Stable na3 2.5% BPO 28 100 ◦C Stable 103 nm (PCS)4 5% BPO 28 100 ◦C Stable 90 nm (PCS)5 2.5% AIBNb 1 120 ◦C Chalky, settles na6 3.5% BPO (blend)c na na Chalky settles 0.98 �m (LDS)

PCS: photon correlation spectroscopy, LDS: laser diffraction spectroscopy.

SBO/P

agaf

a2wS5swtffi

sBw

a Ref. [17].b 2,2′-Azobis(isoburyonitrile).c Acrylic polymer of same composition pre-formed at 100 ◦C, blended with the E

bstraction by free radical initiators, thus providing sites for acrylicrafting [5,16]. Similarity in structure between BPA epoxy polymersnd ESBO polyether polyols led us to believe that they might alsoorm useful acrylic graft co-polymers.

A 20/80 weight ratio PG ESBO polyether polyol was prepareds described in Section 2.2.1 of this report. A mixture by weight of0 MAA/10 hydroxypropyl methacrylate (HPMA)/35 MMA/35 BMAas fed into the PG ESBO polyether polyol at a 2:1 weight ratio.

ufficient BC was added to the ESBO PG polyether polyol to give a0% polymer solution. Graft temperatures as listed in Table 3 wereelected for each reaction to give initiator half lives of 30 min. DMEAas added at the end of the acrylic polymerization as a 30% solu-

ion in distilled water at an 80% equivalent ratio to MAA carboxylunctionality. Additional distilled water was then added to give anal solids level of 25%, and dispersion quality was observed.


Tertiary butyl perbenzoate (TBP) and TBPO give stable disper-ions (see Table 3), which showed no signs of settling after 1 month.PO at 2.5 and 5.0 wt% on monomer gave stable dispersions whichere translucent. A chalky dispersion, which settled in 24 h, was

2nd hea tup

-31 .65°C

-17 .61°C

4.02°C

-30 .03°C (I)

-37 .07°C

-25 .67°C

-10 .68°C (I)

-11.63°C

-7.35°C

)ni

m(e

miT

Fig. 9. DSC thermogram: 2:1 weigh

G polyether polyol, and then inverted.

obtained with 2,2′-azobis(isobutyronitrile) (AIBN). A non-graftedpolymer blend was made by mixing the ESBO PG polyether polyolwith an acrylic polymer of the same composition. This acrylic wasprepared with 3.5% BPO in BC and subsequently mixed into thepolyether polyol just prior to inversion into water. Particle sizes ofthe dispersions made from graft co-polymers prepared with BPOwere about an order of magnitude smaller than the one preparedwith a simple blend of the polyether polyol and acrylic polymer.

Extent of grafting as indicated by emulsion stability and parti-cle size (see Table 3) correlates well with grafting efficiencies forthese initiators previously reported by van Drumpt and Ooster-wijk [17]. A grafting efficiency for each initiator was determinedby preparing 0.01 molar solution of the initiator in n-pentadecane.Under a helium atmosphere the solution was heated to the tem-perature at which each initiator has a half life of 15 min, and held


for 45 min. After cooling to room temperature the liquid phase wasanalyzed for dimer content. The amount of dimer formed as a wt% ofn-pentadecane was taken to be the grafting efficiency. TBP, TBPO,and BPO, which have grafting efficiencies ranging from 16 to 49,

-0. 06

-0. 04

-0. 02

0.00

No

nre

v H

ea

t F

low

(W

/g)

0 12

-0. 10

-0. 08

-0. 06

-0. 04

0 0

Re

v H

ea

t F

low

(W

/g)

t ratio ESBO polyol to acrylic.





81.50°C (I)

55.67°C

99.55°C

-31 .06°C (I)

-41 .14°C

-28 .79°C

-11.42°C(I)

-14 .95°C

-6.55°C

-30 .07°C3.63°C

2nd heat up

)(

-0. 06

-0.04

-0.02

0.00

No

nre

v H

ea

t F

low

(W

/g)

-0. 12

-0. 10

-0.08

-0.06

-0. 04

Re

v H

ea

t F

low

(W

/g)

-50 0 50 10 0 15 0

Fig. 10. DSC thermogram: 1:2 ESBO polyol to acrylic.

Table 4Graft co-polymer synthesis, formulation, and cure.

Run Polyol/ESBO Monomer Initiator NV Crosslinkera MEK DR

1 TMP 20/80 10HPMA/2 MAA/44 BA/44 ST 1% TBP 30% BZ 802 PG 10/90 8 HPMA/46 ST/46 BA 2% TBP 30% BZ 203 PG 10/90 8 HPMA/46 ST/46 BA 2% TBP 15% BZ + 75

15% PH4 PG 20/80 8 HPMA/15 MAA/39 ST/38 BA 3% BPO 10% MEL 405 PG 20/80 8 HPMA/15 MAA/39 ST/38 BA 3% BPO 20% MEL 90

B C.en 77

fetd

cpebhshp

3

scbnsuabtHppf

6 PG 20/80 8 HPMA/15 MAA/39 ST/38 BA

ake for runs 1–3 and C-2 was 17 s at 230 ◦C. Bake for runs 4–6 was 10 min at 190 ◦a BZ: benzoguanamine (Cymel 1123, Cytec Industries, Inc.), PH: phenolic (Rutaph

ormed stable dispersions. However, AIBN, which had a graftingfficiency of 1, did not produce a stable dispersion. The blend ofhe pre-formed acrylic with the PG ESBO polyether polyol also pro-uced a chalky mixture which quickly settled.

Figs. 9 and 10 are DSC second heat up thermograms of grafto-polymers prepared at a 2:1 and a 1:2 weight ratio of ESBO PGolyether polyol to acrylic. Tg’s for the first co-polymer with anxcess of the polyether polyol were well defined, and were taken toe −30 and −11 ◦C. The second co-polymer with an excess of acrylicad fairly broad and weak Tgs of −30, 11, and 82 ◦C. It is thought thatufficient grafting of acrylic monomer to the polyether polyol at theigher acrylic level has produced a more uniform co-polymer com-osition on a molecular level, and thus the absence of distinct Tgs.

.5. Polyether polyol acrylic co-polymer crosslinked films

Three ESBO polyether polyol acrylic graft co-polymers wereynthesized as described in Table 4, and then formulated withrosslinkers. All graft co-polymers were made at 50% solids in BC,ut the graft co-polymer used to formulate runs 4, 5, and 6 was theneutralized with DMEA and inverted into water to give 25% finalolids. Benzoguanamine, phenolic, and melamine crosslinkers weresed at 10–30% of the formulation. Films were then baked at timend temperatures listed. All six films had excellent adhesion andlush resistance. Cure as measured by MEKDR ranged from 20 rubso 100 rubs. Pencil hardness for formulas 4, 5, and 6 increased from


at 10% Cymel 303 to 3H for 20% and 30% Cymel 303. The coatingrepared from run #1 had only 2% wedge bend failure. Coatings pre-ared from runs 4, 5, and 6 all showed no cracking at the maximumorward and reverse impact that the Al substrate was capable of

3% BPO 30% MEL 100

00LB, Hexion chemical co.), MEL: melamine (Cymel 303, Cytec Industries, Inc.).

withstanding without tearing. Overall, these results compare favor-ably with a BPA epoxy control, which had 100 MEKDR, 25% wedgebend failure, no blush, 100% adhesion and 4H pencil hardness.

4. Conclusion

We have investigated ESBO polyether polyols and acrylicgrafted ESBO polyether polyols as potential bio-renewablereplacements for BPA epoxy based coatings. ESBO has an averageof 4.5 epoxide groups per triglyceride. Lewis acids catalyze theESBO epoxide ring opening reaction with hydroxyl materials togive polyether polyols. After 3 h at 115 ◦C 0.01% zinc triflate wasfound to give over 99% conversion with ESBO and n-butanol, whilemethanesulfonic acid and boron trifluoride etherate at 0.5% gaveonly about 50% conversion under the same conditions. As then-butanol concentration was reduced, dimers, trimers, and highermolecular weight analogs of the polyether polyol triglyceridewere noted in GPC traces. Trimethylolpropane when used in placeof n-butanol gave polyether polyols with Mw well over 10,000.Addition of methyl amyl ketone, a non-functional solvent in thissystem, gave lower molecular weights under equivalent reactionconditions to neat reactions. ESBO polyether polyols prepared withpropylene glycol were crosslinked with phenolic resins. Overallfilm properties (solvent and blush resistance, adhesion and wedgebend flexibility) were inferior to a commercial BPA epoxy control.

ESBO PG polyether polyols were grafted with a mix of acrylic


monomers that included MAA. After neutralization with DMEA,they were inverted into water to form 25% solids dispersions. Wheninitiators with high grafting efficiencies were used to make co-polymers, stable dispersions with particle sizes in the 100 nm range


ING Model

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ere obtained. An initiator with a low grafting efficiency gave ahalky dispersion with a particle size of about 2 �m, as did a sim-le blend of ESBO PG polyether polyol with a pro-formed acrylic ofhe same composition.

ESBO PG acrylic graft co-polymers made in BC at 50% solids werevaluated as solvent borne coatings, or inverted into water andvaluated as water borne coatings. Coatings prepared with ben-oguanamine, melamine, and phenolic crosslinkers had excellentdhesion and good blush and solvent resistance, comparing favor-bly to a commercial BPA epoxy control. ESBO polyether polyolcrylic graft co-polymers show potential as BPA epoxy food andeverage can coatings replacements.


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[[[[

PRESSic Coatings xxx (2013) xxx– xxx

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synthesis of polyether polyols with epoxidized soy bean oil

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