CA1102037A - Block polymers of acrylic segments and polymercaptan segments - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A block polymer of the repeating units ?A??B??A?
wherein ?A? is of a hard acrylic segment having a glass transition temperature of 25°C and above; and ?B? has the formula where R is an alkylene group having 2-6 carbon atoms;
R1 is aliphatic, cycloaliphatic or aromatic group;
R2 is a polyester or a polyalkylene ether segment and n is from 0-10.
The polymer is useful in coating compositions, in particular, coating compositions for flexible hydrocarbon rubber and poly-vinyl chloride substrates used in automobiles and trucks.

Description

Back~round of the Invention This invention is related to block polymers, a process for making these polymers and to coating composi-tions containing these polymers.
In modern automobiles and trucks, flexible plastic or rubber substrates are used, for example, flexible filler panels are located between the bumper and the chassis, flexible materials are used as fender extensions around headlights and taillights and other flexible exterior trim parts are used. Finishes are applied to these flexible parts to provide the truck or auto-mobile with a pleasing aesthetic appearance but these finishes must have excellent durability, weatherability and flexibility. Flexible finishes useful for automobiles and trucks are taught by Hick U.S. Patent 3,841,895 issued October 15, 1974. While these finishes are of a good quality, there is a need for finishes with increased durability and coating compositions that can be used to repair flexible finishes.
The block polymer of this invention is used to make coating compositions t~at form excellent flexible finishes and that are useful for reparing flexible finishes.
- Summary of the Invention A block polymer consisting essentially of the repeating units of ~A~B~A~
wherein [A] comprises 15-85~ by weight of the polymer of a hard acrylic segment having a glass transition temperature of 25C and above; and wherein [B] comprises 85-lS~ by weight Z~37 of the polymer and has the formula t~ H 1 H n 2 ~ ~I 1 H 1l 2 n H 1 -S-R-O-C-N-R -N-C~O-R -O-C-N-R -N-C~nO-R -O-C-N-R -O ~ ~
H ~
N-C-O-R-S-where R is an alkylene group having 2-6 carbon atoms;
R is aliphatic, cycloaliphatic or an aromatic group;
R is a polyester of polyalkylene ether segment and n is from 0-10.
A process for preparing the polymer and coating compositions of the polymer al~o are part of thls invention.

Description of the Preferred Embodiments The block polymer is useful in forming coating compositions in particular coating compositions that provide flexible finishes.
m ese coating compositions are useful for finishing flexible plastic or rubber substrate~ used in automoblled such as filler panels, side panelsJ fender extensions, moldings and other trim parts. The flexible substrates can be hydrocarbon rubbers such as ethylene-propylene terpolymer elastomers, poly~inyl chloride, chlorinated rubbers chloro-sulfonated rub-ber, acrylonitrile~butadiene/styrene polymers and the like.
The block polymer is prepared by first forming a polyester or a polyalkylene ether glycol and then the polyester or polyalkylene ether glycol is reacted with an organic diiso-cyanate to form an isocyanate terminated intermediate. This intermediate is reacted with a sufficient amount of a mercapto alkanol to form an -SH terminated intermediate. This -SH
intermediate then is reacted with acrylic monomers to form the block having the aforementioned repeating unit of

2~37 The polyester is prepared by a conventional process in which a dicarboxylic acid or an anhydride thereof is reacted with a poly-hydric alcohol at about 130 to 210C for about 5 to 30 hours in the presence of an esterification catalyst.
Generally a solvent or diluent is used in the process.
Typical polyhydric alcohols that can be used are glycerin, pentaerythritol, trimethylolethane, trimethylolpropane, glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, neopentyl glycol and the like. Typical dicarboxylic acids or the anhydrides thereof that can be used are phthalic acid, phthalic anhydride, isophthalic acid, terephtalic acid, adipic acid, sebacic acid, succinic acid, maleic acid, maleic anhydride, fumaric acid, azelaic acid, dodecanedioic acid and the like.
Typical esterification catalysts that can be used to prepare the polyesters are benzyl trimethyl ammonium hydroxide, tetramethyl ammonium chloride, organic tin compounds, such as dibutyl tin dilaurate, dibutyl tin oxide,and the like, titanium complexes and litharge. About 0.1-4~ by weight, based on the total weight of the polyester,of the catalyst is used.
Typical solvents and diluents which can be used are, for example, toluene, xylene, butyl acetate, acetone, methylisobutyl ketone, methylethyl ketone, isopropanol, butanol, hexane, acetone, ethylene glycol monoethyi ether acetate, V M
and P naptha, mineral spirits and other aliphatic, cycloaliphatic, arcmatic hydrocarbons, esters, ethers and ketones.
It may be desirable to incorporate a small portion of mono-carboxylic aromatic acid into the polyester. Typical acids that can be used are benzoic acid, paratertiarybuty~zoic acid, phenolacetic acid, tri-

3'7 ~thyl benzoic acid and the like.
Also, it may be desirable to incorporate adrying oil fatty acid into the polyester to impart air drying characteristics. Typical drying oil fatty acids that can be used are linseed oil fatty acids, tung oil fatty acids, soya oil fatty acids,dehydrated castor oil fatty acids and the like.
Typical polyalkylene ether-glycols that can be used are poly(tetramethylene ether)glycol poly(propylene ether)glycol, poly(ethylene ether)glycol and the like.
The polyester or polyalkylene ether glycol is then reacted with a sufficient amount of organic diiso-cyanate at about 40 to 125C for about 0.5 to 6 hours to form an isocyanate terminated intermediate.
Typical organic diisocyanates that can be used are as follows: isophorone diisocyanate which is 3-isocyanate-methyl-3,5,5-trimethyl-cyclohe~yl-isocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, butylene-1,3-diisocyanate, hexamethylene diisocyanate, methyl-2,6-diisocyanate caproate, octamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, nonamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, decamethylene diisocyanate, 2,11-diisocyano-dodecane and the like, meta-phenylene diisocyanate, `37 para-phenylene diisocyanate, toluene-2,4-diisocyanate, toluenc-2,6-diisocyanate, xylene-2,~-diisocyanate, xylene-2,6-diisocyanate, dialkyl benzene diisocyanates, such as methylpropylbenzene diisocyanate, methylethylbenzene diisocyanate, and the like;
2,2'-biphenylene diisocyanate, 3,3'-biphenylene diisocyanate,

4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, and the like;
methylene-bis-(4-phenyl isocyanate), ethylene-bis-(4-phen~l isocyanate), isopropylidene-bis-(4-phenyl isocyanate), butylene-bis-(4-phenylisocyanate), hexafluoroisopropylidene-bis-(4-phenyl isocyanate), and the like;
2,2'-oxydiphenyl diisocyanate, 3,3'-oxydiphenyl diisocyanate, 4,4'-oxydiphenyl diisocyanate, 2,2'-ketodiphenyl diisocyanate, 3,3'-ketodiphenyl diisocyanate, 4,4'-ketodiphenyl diisocyanate, 2,2'-thiodipllenyl diisocyana'Le;
3,3'-thiodiphenyl diisocyznate, 4,~'-thiodiphenyl diisocyanate, and the likc;

3Q 2,2'-sul~onediphenyl diisocyanate, ~U2~3'7 3,3'-sul~onediphenyl diisocyanate, 4,4'-sulfonediphenyl diisocyan~te, and the like 2,2'-methylene-bis-(cyclohexyl isocyanate), 3,3'-methylene-bis-(cyclohexyl isocyanate), 4,4'-methylene-bis-(cyclohexyl isocyanate), 4,4'-ethylene-bis-(cyclohexyl isocyanate), 4,4'-propylene-bis-(cyclohexyl isocyanate), bis-(para-isocyano-cyclohexyl)sulfide, bis-(para-isocyano-cyclohexyl)sul~one, bis-(para-isocyano-cyclohexyl)ether, bis-(para-isocyano-cyclohexyl)diethyl silane, bis-(para-isocyano-cyclohexyl)diphenyl silane, bis-(para-isocyano-cyclohexyl) e~hyl phosphine . oxide, bis-(para-isocyano-cyclohexyl)phenyl ?nosphine oxide.
bis-(para-isocyano-cyclohexyl)N-phenyl amine, bis-(para-isocyano-cyclohexyl)N-methyl amine, bis-(4-isocyano-phenyl)diethyl silane, bis-(4-isocyano-phenyl)diphenyl silane, dichloro-biphenylene diisocyanate, - bis-(4-isocyano-phenyl)ethyl phosphine oxide, bis-(4-isocyano-phenyl)phenyl phosphine oxid~
bis-(4-isocyano-phenyl)-N-phenyl amine, bis-(4-isocyano-phenyl)-N-methyl amine, I
3,3'-dimethyl-4,4'-diisocyano biphenyl, .--3,3'-dimethoxy-biphenylene diisocyanate, 2,4-bis-(~-isocyano-t-butyl)toluene, bis-(para-~-isocyano-t-butyl-phenyl)ether, 32~37 para-bis-(2-methyl-4-isocyano-phenyl)benzene, para-bis-(l,l-dimethyl-5-amino-pentyl)benzene, 3,3'-diisocyano adamantane, 3,3'-diisocyano biadamantane, 3,3'-diisocyanoethyl-1,1'-biadamantane, 1,2-bis-(3-isocyano-propoxy)ethane, 2,2-dimethyl propylene diisocyanate, 3-methoxy-hexamethylene diisocyanate 2,5-dimethyl heptamethylene diisocyanate,

5-methyl-nonamethylene diisocyanate, 1,4-diisocyano-cyclohexane, 1,2-diisocyano-octadecane, 2,5-diisocyano-1,3,4-oxadiazole, OCNtCH2)3O(CH2)2O(C1~2)3NCO, OCN(CH2)3S(CH2)3NCO and OcN(cH2)3N(cH2)3NcO- .

Isophorone diisocyanate is preferred since it reacts rapidly and forms a stable intermediate.

The isocyanate terminated intermediate is then reacted with mercapto alkanol at about.:25 to 125C for about 0.5 to 6 hours to form an -SH terminated inter-mediate.
Typical mercapto alkanols that can be used have the formula H-S-R-OH where R is an alkylene group that has 2-6 carbon atoms and are as follows: 1,2-mercaptoethanol, 1,2 and 1,3 mercaptopropanol, mercaptoisopropanol, 1,4-mercaptobutanol, mercaptoisobutanol, mercaptopentanol, 1,6-mercaptohexanol and the like.
The -SH terminated intermediate is then polymerized with acrylic monomers using conventional polymerization techniques in which monomers, solvents such as those mentioned above, intenmediate and ~2~37 polymerization catalyst are charged into a polymerization vessel and heated to about 50-200~C for about 1-6 hours to form a block copolymer.
The resulting block polymer has a number average lecular weight of about 5,000-20,000 and a weight average ~olecular weight of about 20,000 to lO0,000 determined by gel permeation chro~atography using polystyrene as a standard.
About 0.1-4 percent by weight, based on the weight of the above constituents used to prepare the block polymer, of a polymerization catalyst is used.
Typical catalysts are azo-bis-isobutyronitrile, azo-bis (~-gamma-dimethyl-valeronitrilej, benzoyl peroxide, t-butyl peroxy pivalate, di-tertbutyl peroxide and the like.
Typical useful acrylic monomers are alkyl acrylates and methacrylates such as methyl methacrylate, ethyl metha-crylate, pr~pyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and the like, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate and the like; hydroxy alkyl acrylate and methacrylates such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate and the like. Gther monomers can be used with the acrylic monomers such as acrylonitrile, methacrylonitrile, styrene,vinyl toluene,chlorostyrene and the like.
Glycidyl acrylate and glycidyl methacrylate can also be used to provide the polymer with glycidyl groups. Acrylic acid or methacrylic acid can be used to provide a polymer with carboxyl groups that,for example,can be dispersed in water.
Useful block polymers comyrise 15 to 85% by weight of hard acrylic segment and 85 to 15% by weight of polyester or polyalkylene ether 2~3~
segment.
Typical useful blockpol~s are as follows:
~A~ segment ~ segment Methyl methacrylate/hydroxy Neopentyl glycol ethyl acrylate adipate/hexamethylene diisocyanate Methyl methacrylate/butyl ~eopentyl glycol methacrylate/hydroxy ethyl acrylate azelate dodecane dioate/trimethyl hexamethylene diisocyanate Methyl methacrylate/hydroxy 1,6 hexandiol ethyl acrylate/acrylic acid adipate/hexa methylene diisocyanate Methyl methacrylate/hydroxy neopentyl glycol ethyl acrylate/acrylic acid adipate/hexamethylene diisocyanate Methylmethacrylate/butyl methacrylate polyttetramethylene hydroxyethyl acrylate/àcrylic acid ether)glycol/hexa-methylene diisocyanate ~ethyl methacrylate/butyl acrylate poly(tetramethylene acrylonitrile/hydroxyethyl acrylate/ ether)glycol/methyl~ne acrylic acid bis(4-phenyl isocyanate) Styrene/hydroxyethyl poly(tetramethylene ether) acrylate/acrylic acid glycol/hexamethylene diisocyanate Methyl methacrylate/butyl meth- 1,6 hexane diol-neopentyl glycol acrylate/hydroxyethyl acrylate/ adipate/methylene-bis-(cyclo-acrylic acid hexyl isocyanate) Coating compositions prepared with the block polymer contain as the film forming constituents about 50-95% by weight of the polymer and about 5-50~ by weight - of a cross-linking agent. Generally these coating compositions have a solids content of film forming con-stituent of about 5-50~ by weight.
The cross-linking agent used in the coating composition is compatible with the block polymer and can either be an alkylated melamine formaldehyde resin or a polyisocyanate. Typical alkylated melamine formaldehyde resins have one to eight carbon atoms in the alkyl group and are resins that are well known in the art. These resins are prepared by conventional techniques in which a lower alkyl alcohol such as methanol, ethanol, butanol, isobutanol, propanol, isopropanol, hexanol, 2-ethyl hexanol and the like is reacted with a melamine formaldehyde to pro-vide pendent alkoxy groups.
Preferred melamine resills that are used are butylated melamine formaldehyde resins, methylated/
butylated melamine formaldehyde resins and hexa(methoxy-methyl) melamine.
An acid catalyst can be used in the coating composition such as para-toluene sulfonic acid or butyl acid phosphate. An acid catalyst is needed if there is an absence of acid groups in the block polymer or lf a low temperature cure is required, or if a highly etherified melamine resin is used such as hexa(methoxymethyl)-melamine.

A variety of organic polyisocyanates can be used as the crossing agent in the coating composition and in-clude aliphatic, cycloaliphatic, heterocyclic polyiso-cyanates. Typical polyisocyanates are, for example, 4,4'_ methylene-bis-(cyclohexyl isocyanate), tetramethylene diisocyanate, hexamethylene diisocyanate, ethylene diiso-cyanate, cyclohexylene-1,2-diisocyanate, and the like.
Polyisocyanates of a biuret, for example, the biuret of hexamethylene diisocyanate made according to Mayer et al. U.S. Pat. No. 3,245,941, issued ~pril 12, 1966 can also be used.

Organic plasticizers can also be used in the .. 37 coating compo~ition in amounts up to 1-10 percent by weight ba~ed on the weight of ~ilm-forming constituents.
Monomeric and polymeric plasticizers can be used such as phthalate ester plasticizers, and in particular, alkyl an~ cycloal~yl ester phthalates in which the alkyl groups have 2-10 carbon atoms such as dioctyl phthalate, didecyl phthalate, butyl benzylphthalate, dicyclohexyl phthalate and mixtures thereo~. Epoxidized soya bean oil, oil free and oil modified alkyds can also be used as plasticizers.
Polyester resins such as alkylene glycol esters o~ adipic and benæoic acid, for example, ethylene glycol adipate benzoate, ethylene glycol adipate benzoate phthalate, can also be used ln the coating composition of this invention.
The coating composition can be pigmented. Typlcal pigments which can be used are metallic oxides, preferably titanium dioxide, zinc oxide, iron oxide, and the like, metallic flakes, ~uch as aluminum flake, metallic powders, metallic hydrozides, AFFLAIR* pigments, i.e., mica coated with titanium dioxide, sulfateæ, carbonate~, carbon b}acks, silica, talc, china clay, organic pigments and other pigments, and or~anic dyes and lakes. Generally the pigment is formed into a mill base with the block polymer or another polymer and blended into the coating composition.
Other compatible resins can be incorporated into the CoQting composition such as vinyl chloride copolymers, polyurethanes, cellulose acetate butyrate, and silicone resins. Also, ultraviolet light stablizers can be incor-porated into the coating composition.
The coating composition can be formed into a water based finish by using acid constituents in the block * denotes Trade Mark ~32~37 polymer and by neutralizing the polymer wlth ammonia or an amine such as diethylethanol amine and then adding water to form a dispersion or solution. Any of the aforementioned addi-tives, resins, plasticizers and pigments can be incorporated into the aqueous composition by using conventional techniques.
A primer composition is usùally applied to the substrate before the above coating composition is applied, in particular when the coating composition is used over a flexible substrate.
The flexible substrate may be any one of the ell-known saturated or unsaturated hydrocarbon elastomers, e.g., ethylene-propylene copolymer elastomers, particularly one that is made sulfur curable by the inclusion of 1-10 percent by weight nonconjugated diene, because of theix better resistance to oxidative and thermal aging. Butyl rùbber, styrene-butadiene~ubber, polybuta~iene rubber or polyisoprene rubber ~either natural or synthetic) are also used, Typical ethylene-propylene rubbers are those copolymers containing 50-75 weight percent ethylene, 25-45 weight percent propylene, and 2-8 weight percent non-conjugated diene such as 1,4-he~adiene, 5-ethylidene-2-norbornene or dicyclopentadiene.
To prepare a coated article with the coating composition, a primer, if used, is applied by conventional techniques to the substrate by the usual application methods such as spraying, electrostatic sprayiny, dipping, brushing, flow-coating and the like. The primer is then baked at 95 to 145C for 5 to 60 minutes. The coating composition is thcn applicd by onc of thc aforementioned application methods and baked at 95 to 130C Eor 15 to ~1~2~37 60 minutes.
The following Examples illustrate the invention.
All quantities are on a weight basis unless otherwise indicated.

Polyester_Preparation The following constituents are charged into a reaction vessel equipped with a stirrer, reflux condenser, thermometer and a heating mantle:

grams Azelaic acid 752 Dodecanedioic acid920 Neopentyl glycol1032 Toluene _ 150 Total 2854 The resulting composition is heated to its reflux temperature and after 7.5 hours about 0.15-cc of stannous octoate are added and then after about 11 hours about 0.20cc of stannous octoate are added.
Over about 29 hours the temperature of the composition is increased to about 191C. and then held at this temperature for about 12 hours. During this time, about 288 grams of water are removed.
The resulting composition has a solids content of 96.2% of a neopentyl azelate dodecanoate polyester having an acid number of 0.47 and a hydroxyl number of 87.3.
Block Polymer Preparation An -SH terminated intermediate is prepared by charging the following constituents into a five-liter ~1~2~P37 polymerization vessel equipped with a stainless steel stirrer, thermometer, fitted with a nitrogen inlet, dropping funnel and reflex condenser:
Portion 1 Neopentyl glycol/ 520g azelate/ dodecanoate solution (prepared above) Toluene 300g Portion 2 Mixture of 2,2,4 and 2,4,4 tri- 109.7g methylhexamethylene diisocyanate Portion 3 Stannous Octoate 0.15cc Toluene 10.0g Portion 4 2~mercaptoethanol 20.3g Portion 1 is charged into the vessel and stirred for five minutes. Portion 2 is added and stirred for S minutes and the resulting mixture is heated to 60C.
Portion 3 is added over about 5 minutes and the composition is heated to about 115C. and held at this temperature for 15 minutes. Portion 4 is added and the composition is held at 115C. for about 30 minutes.
A monomer mix is prepared by blending together the following:
Methyl methacrylate 622g Butyl methacrylate 259g Hydroxyethyl acrylate 155g Total 1036g A block polymer is prepared by adding the 11~2~3 ,~

following constituents to the above prepared -SH terminated intermediate solution.
Portion 1 Monomer Mix (prepared above)400g Ethyl Acetate 200g Por~ion 2 Monomer Mix (prepared above)636g Azobisisobutylonitrile 6g Portion 3 Ethylene glycol monoethyl ether acetate 300g Portion 4 Ethyl Acetate 525g Portion 1 is added and the resulting mixture $s brought to its reflux temperature. Portion 2 is added over a three-hour period while keeping the mixture at its reflux temperature and then held at its reflux temperature for an additional 30 minutes. Portion 3 is added and then Portion 4 is added.
The resulting block polymer solution has a 54.4% by weight solids content and a Gardner Holdt viscosity measured at 25C of W. The polymer has an inherent viscosity of 0.226 measured at 0.5% solids in 1,2-dichloroethane at 30C and has a number average molecular weight of 11,700 and a weight average molecular weight of 32,400. The above molecular weights are determined by gel permeation chromatography using polystyrene as a standard. The block polymer contains 30% neopentyl glycol azelate dodecanoate, 6.58% trimethyl hexamethylene diisocyanate, 1.21%
2-mercaptoethanol 37.33% methyl methacrylate, 15.54% butyl methacrylate 3~

and 9.3~S~ hydroxyethyl acrylate.
A coating composition o~ 37 parts by weight of the above-prepared block polymer æolution are blended ~rith 3.3 parts by weight of DESMODI~R* N (biuret o~ hexamethylene diisocyanate), and a film of this coating co~position is drawn down on a glass plate and baked for 30 minutes at 107C. and then cured at room temperature for one week. The fi~n is then tested for tensile strength, % elongation at break and initial modulus at 25C., -18C. and -29C.
with the ~ollowing results:

Tensile Strength Initial Test Pounds per square S~ Elongation Modulus Te~peratureinch (psi) at Break (psi~
25C. 2300 62 41,000 -18C. 5300 36 117,000 -29C. 6400 20 152,000 A white mill base is prepared as follows:
Titanium Dioxide 1800g Pigment Block Polymer Solution (Prepared above) 818g Solvent mixture 800g (25% toluene, 25%
ethylene glycolmonoethyl ether acetate and 50%
cellulose acetate) Total 3418g The above constituents are blended together and ground ~or one pass through a standard sandmill operated at a rate of one gallon per hour. The resulting mill base has a calculated pigment to binder ratio of 3o * denotes trade mark ~3'~3~

404/100.
A white paint is prepared as follows:
~lock Polymer Solution 2714g (prepared above) Ethyl Acetate 1262g TINUVIN* 328 (Benzotriazole U V Screener) 60g White Mill ~ase (prepared above) 1724g Total 5760g The resulting paint has a pigment to binder ratio o~ 49/100, a solids content of about 45% and a ~1 Zahn cup visco~ity of 91 sec. measured at about 25C.
A cross linkable paint is prepared by mixing together the following constituents:
White paint (prepared above) lOO.OOg Solvent Mixture (2 parts by 74.40g volume ethylacetate/1 part by ~olume ethylene glycol monobutyl ether acetate) Isocyanate solution (33% 15.23g by weight of the biuret of hexamethylene diisocyanate in a solvent o~ xylene/ethylene glycol monoethyl ether acetate/
ethyl acetate in a 10/10/80 ratio) Retarder solution (0.27% of 7.70g dibutyl tin dilaurate in acetyl acetone) Total197.33g * denotes trade mark _ 18 -.~

~2~37 This cross linkable pai.nt has the following characteristics:

Time After mixing Brookfield Viscosity ~measured using #2 spindle at 100 rpm at 25C) Initial 30.8 centipoises 1 day 33.6 2 days 34.4 3 days 36.8 4 days 39.2 The crosslinkable paint after mixing is sprayed onto three primed steel panels and either dried at room temperature or baked and then the gloss and ~noop hardness of each resulting paint film is measured. The results are as follows:

Bake Film thic~ness Knoop Hardness Time A~ter ~e 2 Hrs.24 Hrs. 48 Hrs. 480T~s.
None 2 mils - 2.6 3.6 4.2 30 minutes at 82C2 mils 2.94.0 4.4 4.8 30 minutes at 108C 2 mils3.9 4.4 4.7 4.9 The gloss o~ the film baked for 30 minutes at 82C is 73-76~ at 20 and 88~ at 60.
The paint films have excellent weatherability and durability.
A ~-inch thick polyester urethane flexible rubber substrate is coated with the above crosslinkable paint and the resulting finish on the rubber is cured for two weeks at about 22C and then baked at 107C for 30 minutes. The finish did not crack at -30C when the rubber with the finish exposed was bent double over a ~-inch diameter steel mandrel.

3~

The following consituents are charged into a reaction vessel equipped as in Example 1:
Portion 1 Polyester Solution (40% polyester 300.0g of neopentyl glycol/1,6 hexane diol (40/60 molar ratio) adipate having an acid number of 0.2, a hydroxyl number of 99.8 and a number average molecular weight of 1124,determined by gel permeation chromatography,in an organic solvent.) Toluene 200.0g Portion 2 Hexamethylene diisocyanate 50.6g Portion 3 Stannous octoate O.lcc Portion 4 2-mercaptoethanol 8.3g Portion 5 Monomer mixture (60% methyl 150.0g methacrylate, 25% butyl methacrylate and 15%
2-hydroxyethyl acrylate) Ethyl acetate lOO.Og Portion 6 Monomer mixture (described above) 241.2g Azobisisobutyronitrile 2.25g Portion 7 Ethylene glycol monoethyl ether 200.0g acetate Portion 8 Ethyl acetate 214.0g ~32~`37 Portion 1 is charged into the reaction vessel and heated to about 90C. Portion 2 is added and Portion 3 then is added and the resulting reaction mixture is heated to its reflux temperature of about 115 C for about 15 minutes. Por-tion 4 is added and the reaction mixture is held a~ its reflux temperature for about 30 minutes. A sample is removed from the reaction mixture and checked with an infrared spectophoto-meter to determine if isocyanate groups are present. If isocyanate groups are present, the reaction mixture is held at its reflux temperature for an additional 30 minutes. If no isocyanate groups are present, Portion 5 is added and the reaction mixture is brought to its reflux temperature. Por-tion 6 is added at a uniform rate over a three hour period while maintaining the reaction mixture at its reflux tempera-ture and then held at this temperature for an additional 30 minutes. Portion 7 is added and then Portion 8 is added.
The resulting block polymer solution has a polymer solids content of 55% by weight and a Gardner Holdt viscosity measured at the above solids and at 25C of X.
The polymer has an inherent viscosity of 0.352 measured at 303C on a 0.5% polymer solids solution using 1,2-dichlorethane as the solvent. The polymer has a number average molecular ~eight of about 13,200 and a weight average molecular weight of about 38,000 measured as in Example 1.
The polymer contains 40% neopentyl glycol/1,6 hexane diol adipate, 6.74% hexamethylene diisocyanate, 1.11% 2-mercapto-ethanol, 31.29~ methyl methacrylate, 13,04% butyl methacrylate and 7.82% 2-hydroxyethyl acrylate.
A white mill base is prepared as in Example 1 except the above prepared polymer solution is used in place ~2~37 of the graft copolymcr solution of Example 1. A white paint is prepared as in Example 1 except the a}~ove white mill base is used. A crosslinkable paint is prepared as in ~xample 1 except the above white paint is used.
The resulting crosslinkable paint is sprayed onto primed steel panels and ba.;ed as in Example 1. The resulting finish has good hardness and gloss and is weatherable. The paint is sprayed onto the rubber substrate described in Example 1 and cured and baked as in Example 1 and forms a finish which has excellent flexibility.

The following constituents are charged into a reaction vessel equipped as in Example 1:
Portion 1 Polyester (Neopentyl glycol/1,6320.0g hexane diol (40/60 molar ratio~ adipate having a hydroxyl number of 34.6 and a number average molecular weight of 3240 determined by gel permeation chromatography) Toluene 272.0g Portion 2 4,4'-n~thylene-bis-(cyclohexyl isocyanate) 39 g Portion 3 Stannous octoate 0.2cc Portion 4 2-mercaptoethanol 7.7g Portion 5 Monomer mixture (84~ methyl metha-218.0g cryIate, 12~ hydroxyethyl acrylate, 4% acrylic acid) ~1~2~37 Acetone 48.0g Portion 6 Monomer mixture (described above) 218.0g Azobisisobutyronitrile 1.7g Portion 7 Dimethylethanolamine 21.5g Portion 8 Water 1525.0g Portion 1 is charged into the reaction vessel and heated to about 90C. Portion 2 is added. Portion 3 then is added and the resulting reaction mixture is heated to its reflux tempera.ure for about l~S minutes. Portion 4 is added and the reaction mixture is held at its reflux temperature for about 30 minutes. A sample is removed from the reaction mixture and checked with an infrared spectophotometer to determine if isocyanate groups are preserlt. If isocyanate groups are present, the reaction mixture is held at its reflux temperature for an additional 30 minutes. If no isocyanate groups are present, Portion 5 is added and the reaction mixture is brought to its reflux temperature.
Portion 6 is added at a uniform rate over a three-hour period while maintaining the reaction mi,xture at its reflux temperature and then held at this temperature for an addi-tional 30 minutes. Portion 7 is added and then Portion 8 is added.
The resulting aqueous block polymer dispersion has a polymer solids content of about 30% by weight and pH of about 7.0 and a Brookfield viscosity of 77 centipoises measured at 25C using a #l spindle at 50 rpm.
The polymer has an inherent viscosity of 0.307 2Ç~37 measured at 30C. on a 0.5% polymer solids solution using 1,2-dichlorethane as the solvent. The polymer has a number average molecular weight of about 10,600 and a weight average molecular weight of about 29,000 measured as in Example 1. The polymer contains 40.02 neopentyl glycol/
1,6 hexane diol adipate, 4.88% 4,4'-methylene-bis-(cyclohe~l isocyanate) diisocyanate, 0.96% 2,mercaptoethanol, 45.48% methyl metha-crylate, 6.49% 2,hydroxyethyl acrylate and 2.17% acrylic acid.
A white paint is prepared by grinding the following constituents in a sand mill:
Polymer dispersion (prepared above) 425.0g Methylated melamine resin solution 21.8g (80% solids in isopropanol) Diethylene glycol monobutyl ethers 20.0g Titanium dioxide pigment 25.0g The resulting paint has a 31 second viscosity measured with a ~2 Zahn cup at 25C.
The above paint is sprayed onto a primed flexible ethylene propylene rubber substrate and cured and baked as in Example 1 to form a fle~ible glossy finish that has good weatherability and durability.
ExArllpLE 4 The following constituents are charged into a reaction vessel equipped as in Example 1:
Portion 1 Poly(tetramethylene ether) 800.0g glycol having a weight average molecular weight of about 1000 measured by gel permeation chromatography 11~2~7 Toluene 800.0g Portion 2 4,4'--methylene-bis-(cyclohexyl isocyanate) 2000.0g Portion 3 Stannous octoate 0.4cc Portion 4 2-mercaptoethanol 406.0g Portion 5 Monomer mixture (60% methyl metha-496.0g crylate, 25% butyl methacrylate, 12~ 2-hydroxy ethylene acrylate and 3% acrylic acid) Portion 6 Monomer mixture (described above)360.0g Toluene 80.0g Azobisisobutyronitrile 4.0g ~ortion 7 Isopropyl alcohol 408.0g Portion 1 is charged into the reaction vessel and heated to about 90C. Portion 2 is added and Portion 3 then is added and the resulting reaction mixture is heated to its reflux temperature of about 110 C for about 15 minutes. Portion 4 is added and the reaction mixture is held at its reflux temperature for about 30 minutes. A sample is removed from the reaction mixture and checked with an infrared spectophotometer to determine if isocyanate groups are present. If isocyanate groups are present, the reaction mi.xture i5 held at its reflux temperature for an additional 30 minutes. Portion 5 is added and the reaction mixture is brought to its reflux temperature. Portion 6 is added at a uniform rate over a three-hour period while maintaining the 2~37 reaction mixture at its reflux temperature and then held at this temperature for an additional 15 minutes. Por-tion 7 is added.
The resulting block polymer solution has a polymer solids content of 62% by weight and a Gardner Holdt viscosity measured at the above solids and at 25C of about ~5.
The polymer has an inherent viscosity of 0.369 measured at 30C on a 0.5% polymer solids solution using 1,2-dichlorethane as the solvent. The polymer has a number average mole~ular weight of ll,000 and a weight average molecular weight of 32,000 measured as in Example l.
The polymer contains 41.05% poly(tetramethylene ether) glycol, 13.53~ 4,4'-methylene-bis-(cyclohexyl isocyanate) 1.59% 2-mercapto ethanol, 26.34% methyl methacrylate, 10.96% butyl meth~crylate, 5.22% 2-hydroxyethyl acrylate and 1.31~ acrylic acid.
A cross linkable composition prepared by blending the above-prepared polymer solution with a butylated melamine formaldehyde resin solution such that the ratio of polymer to butylated melamine formaldehyde resin is 80:20. The resulting composition is sprayed onto a primed metal sub-strate and baked at 120C for 30 minutes to provide a hard glossy finish.
A white mill base is prepared as in Example 1 except the above-prepared polymer solution is used in place of the polymer solution of Example 1. A white paint is pre-pared as in Example 1 except the above white mill base is used.
A cross linkable paint is prepared by blending the above white paint with a butylated melamine formaldehyde resin sGlution so that the ratio of polymer to butylated 32~P<3t7 melamlne resin is 80:20. The resulting paint is sprayed onto a flexible ethylene/propylene rubber substrate and baked as above to provide a primer that is flexible and hydrolytically stable. An acrylic enamel can be applied to the primed substrate and provides a high quality finish.

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A block polymer consisting essentially of the repeating units of [-A-] [-B-] [-A-]
wherein [A] comprises 15-85% by weight of the polymer of a hard acrylic segment containing at least one hydroxyl group and having a glass transition temperature of 25°C and above; and [B] comprises 85-15% by weight of the polymer and has the formula where R is an alkylene group having 2-6 carbon atoms;
R1 is an aliphatic, a cycloaliphatic or an aromatic group;
R2 is a polyester segment or a poly-alkylene ether segment; and n is from 0-10, and wherein the block polymer has a number average molecular weight of about 5,000-20,000 and a weight average molecular weight of about 20,000-100,000.

2. The polymer of claim 1 in which [A] consists essentially of an alkyl methacrylate and a hydroxy alkyl acrylate or a hydroxy alkyl methacrylate.

3. The polymer of claim 2 in which R is (CH2)2 and R1 is an aliphatic group and R2 is a polyester or a poly(alkylene ether).

4. The polymer of claim 1 in which ?A? is of an alkyl methacrylate, a hydroxy alkyl acrylate and acrylic acid, R is (CH2)2, R1 is a cycloaliphatic group and R2 is a polyester segment.

5. The polymer of claim 3 in which the ?A?
segment consists essentially of methyl methacrylate and hydroxy ethyl acrylate, R1 is (CH2)6 and R2 consists essentially of neopentyl glycol adipate.

6. The polymer of claim 3 in which the ?A?
segment consists essentially of methyl methacrylate, butyl methacrylate and hydroxy ethyl acrylate, R1 is trimethylhexa-methylene, and R2 consists essentially of neopentyl glycol azelate/dodecane dioate.

7. The polymer of claim 1 in which the ?A?
segment consists essentially of methyl methacrylate, hydroxy ethyl acrylate and acrylic acid, R is (CH2)2, R1 is (CH2)6 and R2 consists essentially of a neopentyl glycol/ 1,6 hexane diol adipate polyester.

8. The polymer of claim 1 in which the ?A?
æegment consistæ essentially of methyl methacrylate, hydroxy ethyl acrylate and acrylic acid, R is (CH2)2, R1 is (CH2)6 and R2 is neopentyl glycol hexane diol adipate polyester.

9. The polymer of claim 1 in which the ?A?
segment consists essentially of methyl methacrylate, butyl methacrylate, hydroxy ethyl acrylate and acrylic acid, R is (CH2)2, R1 is bis-(cyclohexyl methane) and R2 is poly(tetra-methylene ether) glycol.

10. The polymer of claim 1 in which the ?A?
segment consists essentially of methyl methacrylate, butyl acrylate, acrylonitrile, hydroxy ethyl acrylate and acrylic acid, R is (CH2)2, R1 is and R2 is poly(tetramethylene ether) glycol.

11. The polymer of claim 1 in which the A
segment consists essentially of hydroxyethyl acrylate, acrylic acid and styrene, R is (CH2)2, R1 is (CH2)6 and R2 is poly(tetramethylene ether) glycol.

12. The polymer of claim 1 in which the A
segment consists essentially of methyl methacrylate, butyl methacrylate, hydroxy ethyl acrylate and acrylic acid, R is (CH2)2, R1 is bis-(cyclohexyl methane) and R2 is polyester of 1,6 hexane diol adipate and neopentyl glycol adipate.

13. A process for preparing the block polymer of claim 1 which comprises the steps of (1) contacting an organic diisocyanate with a polyester or a poly(aIkylene ether) glycol at about 40-125°C for about 0.5-6 hours to form an isocyanate terminated intermediate;
(2) contacting the isocyanate terminated intermediate with a mercapto alkanol of the formula H-S-R-OH where R has 2-6 carbon atoms to form an -SH terminated intermediate;
(3) polymerizing the -SH terminated inter-mediate with acrylic monomers wherein at least one of the monomers contains a hydroxyl group and a polymerization catalyst at about 50-200°C
for about 1-6 hours to form the block polymer.

14. A coating composition comprising 5-50% by weight of the block polymer of claim 1 and a solvent for the polymer.

15. An aqueous coating composition comprising 5-50% by weight of the block polymer of claim 1 dispersed in an aqueous medium.

16. A coating composition comprising 5-50% by weight of film-forming constituents consisting essentially of 50-95% by weight of the block polymer of claim 1 and 5-50% by weight of a cross-linking agent.

17. The coating composition of claim 16 in which the crosslinking agent is an organic polyisocyanate.

18. The coating composition of claim 16 in which the crosslinking agent is an alkylated melamine formaldehyde resin.

19. A flexible substrated coated with a dried crosslinked layer of the coating composition of claim 16.