WO1995011927A1

WO1995011927A1 - Polyester-modified polydiene/acrylourethane oligomers

Info

Publication number: WO1995011927A1
Application number: PCT/US1994/010967
Authority: WO
Inventors: Frances G. Dennis; Robin F. Righettini; Richard J. Ambrose
Original assignee: Lord Corporation
Priority date: 1993-10-26
Filing date: 1994-09-28
Publication date: 1995-05-04

Abstract

A polyester-modified polydiene/acrylourethane oligomer which is the reaction product of an olefinically unsaturated compound and a polyester-modified polydiene urethane prepolymer. The polyester-modified polydiene urethane prepolymer is the reaction product of a polyisocyanate and a polyester-modified polydiene-polyol. The polydiene polyol is modified to contain polyester functionality by reacting the polydiene polyol with a polyester-forming monomer such as a lactone, a hydroxyl-functional carboxylic acid or a hydroxyl-functional carboxylic acid ester. The acrylourethane oligomer may be utilized in combination with a reactive diluent system to form a radiation-curable composition which does not undergo phase separation upon storage. Upon cure, the radiation-curable composition forms a protective coating which exhibits excellent resistance to stain and wear.

Description

POLYESTER-MODIFIED POLYDIENE/ACRYLOURETHANE

OLIGOMERS

Technical Field

The present invention relates to radiation-curable oligoiri ? useful in coating compositions. More specifically, the present invention relates to a polydiene/acrylourethane oligomer which has been modified to contain polyester functionality.

Background Art

Acrylourethane oligomers have previously been utilized in combination with various acrylic monomers to produce radiation- curable protective coatings as well as radiation-curable vehicles for materials such as ceramic ink compositions. For example, U.S. Patent No. 4,390,565 describes a radiation-curable ceramic ink composition containing an acrylated polycaprolactone diol polyurethane, an acrylic monomer, and a ceramic frit.

A radiation-curable vehicle for ceramic enamels is described in U.S. Patent No. 4,900,763. The radiation-curable vehicle contains acrylate or methacrylate modified oligomers, monofunctional acrylate or methacrylate modified monomers, pentafunctional acrylate or methacrylate modified monomers, and a photoinitiator system. The photoinitiator system is preferably a blend of a substituted thioxanthone compound, an ester of an aminobenzoic acid, and a 2- phenylacetophenone derivative.

F S. Patent No. 5,003,026 describes a radiation-curable no-wax floor cedin which contains a polymerized urethane-acrylate oligomer which is the reaction product of an aromatic or cycloalkyl diisocyanate, a monohydroxy monoacrylate, and a phthalic polyester polyol.

U.S. Patent Nos. 4,377,679 and 4,512,910 disclose photo :^•, >le compositions prepared by reacting a polyether diol and an acrylic acid in about equal molar proportions to form a reaction product and then reacting the reaction product with a hydroxyalkylacrylate and an organic diisocyanate in about equal molar proportions.

U.S. Patent No. 4,780,487 describes a coating composition which is a mixture of a polydiene-based acrylourethane oligomer and a standard acrylourethane oligomer. The coating composition also utilizes a reactive diluent system which can be one or more compounds which contain unsaturated addition-polymerizable functionality.

Many of the traditional acrylourethane oligomers such as those described above have not been found to be capable of simultaneously providing sufficient stain and wear resistance when utilized in coating compositions. Those oligomers that have been found to be capable of providing sufficient stain and wear resistance are typically deficient in some other aspect. For example, the coating compositions of U.S. Patent No. 4,780,487 have been found to exhibit excellent stain and wear resistance, but the compositions undergo a gross phase separation upon storage. In other words, two distinct layers are formed, each having a volume of about half of the total coating composition. One of the layers primarily contains the polydiene-based acrylourethane oligomer, while the other layer primarily contains the standard acrylourethane oligomer and the reactive diluent system. The polydiene-based acrylourethane oligomer is incompatible with the rest of the ingredients in the coating composition, resulting in gross phase separation. The phase separation occurs rapidly and takes place during the application of the coating, resulting in an inconsistent composition being applied to a substrate or surface. Due to the large size of commercial applicators typically utilized to apply the coating compositions, such as roll coaters or curtain coaters, continuous stirring or mixing of the coating composition is extremely burdensome and inconvenient.

A need therefore exists for a curable coating composition which maintains sufficient stain and wear resistance and which does not undergo gross phase separation upon storage. Disclosure of Invention

The acrylourethane oligomers of the present invention can be utilized in coating compositions with a reactive diluent system so as to greatly reduce or eliminate gross phase separation upon storage. Coating compositions prepared with the present acrylourethane oligomers also exhibit excellent stain a-πd wear resistance. The acrylourethane oligomers of the present invention, referred to as polyester-modified polydiene/acrylourethane oligomers, comprise the reaction product of an olefinically unsaturated compound and a polyester-modified polydiene urethane prepolymer. The olefinically unsaturated compound is preferably a lactone-acrylate adduct prepared by reacting an appropriate lactone with an acrylate or methacrylate acid ester. The polyester-modified polydiene urethane prepolymer is the reaction product of a polyisocyanate and a polyester- modified polydiene polyol. The polydiene polyol is modified to contain polyester functionality by reacting the polydiene polyol with a polyester-forming monomer, such as a lactone, a hydroxyl-functional carboxylic acid, or a hydroxyl-functional carboxylic acid ester.

The present invention is based on the discovery that the introduction of polyester functionality into the polydiene urethane allows for the formation of a polydiene/acrylourethane oligomer which does not undergo gross phase separation in the presence of a reactive diluent system. Without being bound by any theory of operability, it is believed that the polyester functionality allows the polydiene material to behave in a manner analogous to the disperse phase in a non- aqueous dispersion, thereby resulting in minimal phase separation. Best Mode for Carrying Out the Invention

The polyester-modified polydiene/acrylourethane oligomer of the present invention is the reaction product of an olefinically 95 unsaturated compound and a polyester-modified polydiene urethane prepolymer.

The olefinically unsaturated compounds employed for the preparation of the present acrylourethane oligomers may be monomeric or polymeric and are characterized by the presence of a

100 single isocyanate-reactive moiety such as an active hydrogen group. Preferably, the active hydrogen group is in the form of a hydroxyl group. Illustrative of unsaturated addition-polymerizable monomeric organic compounds having a single isocyanate-reactive active hydrogen group are 2-hydroxyl-ethyl acrylate, 2-hydroxyethyl

105 methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl meth¬ acrylate, N-hydroxymethyl acrylamide, N-hydroxyl-methyl methacrylamide, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, tripropylene glycol monoacrylate, butane diol monoacrylate, glycerine dimethacrylate, trimethylol propane

110 dimethacrylate, the reaction products of polyether glycols with acrylic or methacrylic acid, and the like.

The preferred olefinically unsaturated compounds are lactone- modified acrylate or methacrylate acid esters (hereinafter "lactone- acrylate adducts") prepared by reacting an appropriate lactone with 115 an acrylate or methacrylate acid ester.

Lactones employed in the preparation of the lactone-acrylate adducts typically have the formula

wherein R is hydrogen or an alkyl group having from 1 to 12 carbon

120 atoms, x is from 4 to 7 and at least (x - 2) R's are hydrogen. Preferred lactones are the ε-caprolactones wherein x is 4 and at least 6 of the R's are hydrogen with the remainder, if any, being alkyl groups. Preferably, none of the substituents contain more than 12 carbon atoms and the total number of carbon atoms in these substituents on the lactone ring does not exceed 12. Unsubstituted ε-caprolactone, i.e., 125 where all the R's are hydrogen, is a derivative of 6-hydroxyhexanoic acid. Both the unsubstituted and substituted ε-caprolactones are available by reacting the corresponding cyclohexanone with an oxidizing agent such as peracetic acid.

Substituted ε-caprolactones found to be most suitable for

130 preparing the present lactone-acrylate adducts are the various ε- monoalkyl-caprolactones wherein the alkyl groups contain from 1 to 12 carbon atoms, e.g., ε-methylcaprolactone, ε-ethylcaprolactone, ε- propylcaprolactone and ε-dodecylcaprolactone. Useful also are the ε- dialkylcaprolactones in which the two alkyl groups are substituted on

135 the same or different carbon atoms, but not both on the omega carbon atoms. Also useful are the ε-trialkyl-caprolactones wherein 2 or 3 carbon atoms in the lactone ring are substituted provided, though, that the omega carbon atom is not disubstituted. The most preferred lactone starting reactant is the ε-capro-lactone wherein x in the

140 formula is 4 and all the R's are hydrogen.

The acrylate or methacrylate acid esters utilized to prepare the lactone-acrylate adducts contain from 1 to 3 acrylyl or alpha- substituted acrylyl groups and one or two hydroxyl groups. Such esters are commercially available and can be readily synthesized by 145 those skilled in the art. Commercially available esters include the hydroxyalkyl acrylates or hydroxyalkyl methacrylates wherein the alkyl group contains from 2 to 10 carbon atoms, preferably from 2 to 6 carbon atoms. The hydroxyalkyl acrylates and methacrylates have the following formula:

0

CH, OR'OH wherein R' is hydrogen or methyl and R" is a linear or a branched alkylene group having from 2 to 10 carbon atoms, preferably from 2 to 6 carbon atoms.

Examples of suitable hydroxyalkyl acrylates and 155 methacrylates include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxy- butyl acrylate, 3-hydroxypentyl acrylate, 6-hydroxynonyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyl-propyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 160 2-hydroxypentyl methacrylate, 5-hydroxypentyl meth- acrylate, 7-hydroxyheptyl methacrylate and 5-hydroxydecyl methacrylate.

A molar ratio of the lactone to hydroxyl groups in the ester of from about 1:0.1 to about 1:5, preferably from about 1:0.3 to about 1:3 is typically utilized when preparing the lactone-acrylate adduct.

165 Generally, a temperature of from about 25° C to 200° C, preferably from about 120° C to 150° C, is used. Times of reaction vary depending upon the temperature and catalyst used; however, generally, the reaction is allowed to proceed from about 20 minutes to 10 hours, preferably from about 20 minutes to 5 hours. Suitable catalysts for use in the reaction

170 include sulfuric acid, para-toluene sulfonic acid, stannous octoate and butyl titanate.

An example of a lactone-acrylate adduct preferred for use in the present invention is a ε-caprolactone-2-hydroxyethyl acrylate adduct supplied by Union Carbide Corporation under the tradename 175 TONE M-100.

As stated above, the olefinically unsaturated compound is reacted with a polyester-modified polydiene urethane prepolymer in order to prepare the present acrylourethane oligomers. The polyester- modified polydiene urethane prepolymer is prepared by reacting a 180 polyisocyanate and a polyester-modified polydiene polyol.

The polyisocyanate compounds which are employed in forming the polyester-modified polydiene urethane prepolymer in accordance with the present invention can be any organic isocyanate compound having at least two free isocyanate groups. Included 185 within the purview of suitable polyisocyanates are aliphatic, cycloaliphatic, and aromatic polyisocyanates, as these terms are generally interpreted in the art. Thus it will be appre-ciated that any of the known polyisocyanates such as alkyl and alkylene polyisocyanates, cycloalkyl and cycloalkylene polyisocyanates, aryl and 190 arylene polyisocyanates, and combinations such as alkylene, cycloalkylene and alkylene arylene polyisocyanates, can be employed in the practice of the present invention.

Suitable polyisocyanates include, without limitation, toluene- 2,4-diisocyanate, 2,2,4-trimethylhexamethylene-l,6-diisocyanate,

195 hexamethylene- 1,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, triphenylmethane-4,4',4"-triisocyanate, polymethylene polyphenyliso- cyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6- toluene diisocyanate, 1,5-naphthalene diisocyanate, naphthalene- 1,4- diisocyanate, diphenylene-4,4'-diisocyanate, 1,4-cyclohexylene

200 dimethylene diisocyanate, xylene-l,4-diisocyanate, xylene-l,3-diiso- cyanate, 2,5(or 6)-Bis(isocyanatomethyl)-bicyclo[2,2,l]heptane, cyclohexyl-l,4-diisocyanate, 4,4'-methylenebis(cyclo-hexyl isocyanate), 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, isophorone diisocya¬ nate, m-tetramethyl xylene diisocyanate, the product obtained by

205 reacting trimethylol propane and 2,4-toluene diisocyanate in a ratio of 1:3, and the like. The diisocyanate compounds are preferred, with 4,4'-methylene-bis(cyclohexyl isocyanate) being especially preferred.

The polyester-modified polydiene polyol to be reacted with the polyisocyanate is prepared by reacting a polydiene polyol and a

210 polyester-forming monomer. The polydiene polyol can essentially be any hydroxylated polymer of a conjugated diene having from about 4 to 12 carbon atoms. The polydiene polyols are typically prepared by the free radical polymerization of butadiene monomers employing hydrogen peroxide as the initiator in a mixed aqueous-organic

215 medium to ensure cosolubility of monomer and initiator. The polydiene polyol may also be hydrogenated prior to use in the present invention. The hydrogenation of polydiene polyols is typically carried out by, for example, catalytic hydrogenation as is known in the art. Further descriptions of polydiene polyols and their preparation can be 220 found in U.S. Patent No. 3,652,520 and in Schneider et al., "Structure and Properties of Polybutadiene Polyurethanes," Advances in Urethane Science and Technology. Vol. 8, 1981, pp. 49-52. Many polydiene polyols are also commercially available.

Specific examples of polydiene polyols useful in the present 225 invention include hydroxylated polybutadiene, hydroxylated 2,3- dimethyl-butadiene, hydroxylated polyisoprene, hydroxylated poly- hexadiene, hydroxylated polyheptadiene, hydroxylated polyoctadiene, and the like, including the hydrogenated analogs thereof. The presently preferred polydiene polyol is hydroxylated polybutadiene.

230 The polyester-forming monomer utilized to prepare the polyester-modified polydiene polyol can essentially be any compound capable of forming a polyester linkage with a hydroxyl group of the polydiene polyol through a condensation reaction. General classes of monomers which are capable of forming a polyester linkage with the

235 hydroxyl group of the polydiene polyol include reactive lactones which react by ring opening; hydroxyl-functional carboxylic acids which form a polyester by loss of water; and hydroxyl-functional carboxylic acid esters which can form a polyester by loss of alcohol.

Specific examples of reactive lactones include ε-caprolactone;

240 β-propiolactone; lactide; β-butyrolactone; α,α-bis(chloromethyl)- propiolactone; δ-valerolactone; α,β,γ-trimethoxy-δ-valerolactone; 1,4- dioxane-2-one; glycolide; l,4-dithiane-2,5-dione; trimethylene carbonate; neopentylene carbonate; ethylene oxalate; propylene oxalate; β-methyl-ε-isopropyl-ε-caprolactone; lactone of 4-hydroxy-

245 cyclohexanecarboxylic acid; cϊs-disali-cylide; di-o-cresotide; and trisalicylide, with ε-caprolactone being presently preferred.

Specific examples of hydroxyl-functional carboxylic acids include 2-hydroxyl benzoic acid, 3-hydroxyl benzoic acid, 4-hydroxyl benzoic acid, lactic acid, 11-hydroxyl undecanoic acid, and 9-hydroxyl 250 nonanoic acid. Specific examples of hydroxyl esters include the ester analogs of the carboxylic acids described immediately above.

In general, reactive lactor- →, are the preferred polyester- forming monomers for use in the pi -sent invention and therefore, l- 255 caprolactone is the presently most preferred polyester-forming monomer for use in the present invention.

The polyester-modified polydiene polyol is typically prepared by reacting the polydiene polyol with the polyester-forming monomer in the presence of a transesterification catalyst at a temperature ranging

260 from about 90°C to 180°C, preferably from about 140°C to 160°C, for a period of time ranging from about 1 to 12 hours, preferably from about 2 to 8 hours. In the case where the polyester-forming monomer is a reactive lactone, an equivalent ratio of the lactone to hydroxyl groups in the polydiene polyol of from about 1:0.1 to about 1:5, preferably from

265 about 1:0.3 to about 1:3 is typically utilized. Transesterification catalysts are known in the art and examples thereof include tetralkoxytitanium compounds such as titanium tetrabutoxide; various tin catalysts such as stannous octoate; and other acid or base catalysts known in the art for use in transesterification reactions.

270 Tetralkoxytitanium compounds are presently preferred for use as transesterification catalysts in the present invention.

When reacting the polyisocyanate and the polyester-modified polydiene polyol to prepare the polyester-modified polydiene urethane prepolymer, the amount of polyisocyanate will typically be sufficient to 275 provide an NCO:OH ratio, with respect to the polyester-modified polydiene polyol, in the range of about 1.5:1 to 3.5:1, preferably in the range from about 2.0:1 to 3.05:1. A conventional urethane catalyst such as a tin catalyst (e.g., butyl tin mercaptide) may be utilized to catalyze the polyisocyanate-polyol reaction.

280 As stated above, the polyester-modified polydiene/acrylo¬ urethane oligomer of the invention is prepared by reacting the olefinically unsaturated compound with the polyester-modified polydiene urethane prepolymer, and this can be earned out by any of several reaction routes. The acrylourethane oligomer is typically 285 prepared by directly reacting the olefinically unsaturated compound with the polyester-modified polydiene urethane prepolymer. Alternatively, and in the case where the olefinically unsaturated compound is a lactone-acrylate adduct, the oligomer may be prepared by the simultaneous reaction of the polydiene polyol, the acrylate or

290 methacrylate acid ester, and the lactone, followed by addition of the polyisocyanate. In this procedure, the lactone simultaneously modifies the polydiene polyol to contain polyester functionality and forms the lactone-acrylate adduct with the acrylate or methacrylate acid ester. The acrylourethane oligomer may also be prepared by first

295 reacting the polyisocyanate with the olefinically unsaturated compound, followed by the addition of the polyester-modified polydiene polyol. Finally, the acrylourethane oligomer may be simply prepared by the simultaneous reaction of the olefinically unsaturated compound, the polyester-modified polydiene polyol and the

300 polyisocyanate. It is presently preferable to prepare the acrylourethane by directly reacting the olefinically unsaturated compound with the polyester-modified polydiene urethane prepolymer.

The acrylourethane oligomers can be prepared neat but are

305 preferably prepared in the presence of certain reactive diluents

(described in detail hereinafter) which are copolymerizable with the acrylourethane oligomer, but are otherwise inert during the process of preparing the acrylourethane oligomers. In order to be inert during the acrylourethane preparation process and therefore act as a reaction

310 medium, the reactive diluent must be free of active hydrogen as determined by the Zerewitinoff test, J. Am. Chem. Soc, 49, 3181 (1927).

If utilized as a reaction medium in the preparation of the acrylourethane oligomers, the reactive diluents are typically employed in an amount ranging from about 1 to 50, preferably from about 10 to

315 30, percent by weight of the total reaction mixture.

As mentioned above, a reactive diluent system is employed in combination with the polyester-modified polydiene/acrylourethane oligomer in the radiation-curable composition of this invention. Broadly, suitable reactive diluent systems comprise at least one 320 unsaturated addition-polymerizable monomer which is copolymerizable with the polyester-modified polydiene/acrylourethane oligomer upon exposure to radiation. The reactive diluent can be monofunctional or polyfunctional. A single polyfunctional diluent can be used, as can mixtures thereof; or a combination of one or more

325 monofunctional reactive diluents and one or more polyfunctional reactive diluents can be used. Particularly preferred reactive diluents are unsaturated addition-polymerizable monofunctional acrylic monomers, unsaturated addition-polymerizable polyfunctional acrylic monomers, and combinations thereof. Monofunctional acrylic

330 monomers useful as a reactive diluent system are well known and examples of such monomers include isobornyl acrylate, phenoxyethyl acrylate, isodecyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2- ethylhexyl acrylate, octyl acrylate, nonyl acrylate, stearyl acrylate, 2- phenoxy acrylate, 2-methoxyethyl acrylate, lactone modified esters of

335 acrylic and methacrylic acid, methyl methacrylate, butyl acrylate, isobutyl acrylate, methacryl-amide, allyl acrylate, tetrahydrofuryl acrylate, n-hexyl methacrylate, 2-(2-ethoxy-ethoxy)ethyl acrylate, n- lauryl acrylate, 2 -phenoxyethyl acrylate, glycidyl methacrylate, glycidyl acrylate, acrylated methylolmelamine, and 2-(N,N-

340 diethylamino)-ethyl acrylate. Examples of polyfunctional acrylic monomers include neopentyl glycol diacrylate, alkoxylated neopentyl glycol diacrylate, ethylene glycol diacrylate, hexylene glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, pentaerythritol di-, tri-, or

345 tetraacrylate, trimethylolpropane triacrylate, alkoxylated trimethylolpropane triacrylate which contains from 2 to 14 moles of either ethylene or propylene oxide, triethylene glycol diacrylate, tetraethylene glycol diacrylate, diacrylate of bisphenol-A diepoxide, polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-

350 butanediol diacrylate, 1,6-hexanediol diacrylate, other diacrylates of butane diols or pentane diols or hexane diols, polyethylene glycol diacrylate, any corresponding methacrylates thereof, and combinations thereof. Preferred reactive acrylic monomer diluents for purposes of the present invention include tripropylene glycol

355 diacrylate, ethoxylated trimethylolpropane triacrylate, and pentaerythritol tetraacrylate. The olefinically unsaturated compounds described hereinabove with respect to the preparation of the polyester-modified polydiene/acrylo-urethane oligomer may also be utilized as reactive

360 diluents in lieu of, or in combination with, the acrylic monomers described above.

Furthermore, various addition polymerizable vinyl monomers may be utilized as reactive diluents in lieu of, or in combination with, the acrylic monomers and the olefinically unsaturated compounds. 365 Examples of vinyl monomers useful as reactive diluents for purposes of the present invention include N-vinyl caprolactam, N-vinyl pyrrolidone, various vinyl ethers, esters of maleic and/or fumaric acid, vinyl acetate and other vinyl esters, and the like.

It should be noted that the acrylic monomers and the vinyl 370 monomers, which are free of active hydrogen, can be used as a reaction medium to prepare the acrylourethane oligomers of the invention. The olefinically unsaturated compounds, however, are not free of active hydrogen and may only be utilized as a reactive diluent system in combination with the final acrylourethane oligomer.

375 The reactive diluent system typically comprises from about 10 to 65, preferably from about 25 to 50, percent by weight of the radiation- curable composition.

The polyester-modified polydiene/acrylourethane oligomer is typically utilized in an amount ranging from about 20 to 80, preferably 380 from about 40 to 65, percent by weight of the radiation-curable composition.

The radiation-curable composition may optionally contain one or more photoinitiators to catalyze or accelerate cure by exposure to ultraviolet radiation. The photoinitiator can be any of the known 385 photoinitiators such as benzophenone, benzoin, acetophenone, benzoin methyl ether, Michler's ketone, benzoin butyl ether, xanthone, thioxanthone, propiophenone, fluorenone, carbozole, diethyoxy- acetophenone, the 2-, 3- and 4- methylacetophenones and methoxy- acetophenones, the 2- and 3- chloroxanthones and chloro- 390 thioxanthones, 2-acetyl-4-methylphenyl acetate, 2,2'-dimethyoxy-2- phenylacetophenone, hydroxycyclohexylphenyl ketone, benzaldehyde, fluorene, anthraquinone, triphenylamine, 3- and 4-allyl-aceto-

)henone, p-diacetylbenzene, 3-chloro-2-nonylxanthone, 2-chlorobenzo- phenone, 4-methoxybenzophenone, 2,2',4,4'-tetrachlorobenzophenone,

395 2-chloro-4'-methylbenzophenone, 4-chloro-4'-methylbenzophenone, 3-methylbenzo-phenone, 4-tert-butyl-benzophenone, isobutyl ether, benzoic acetate, benzil, benzilic acid, amino benzoate, methylene blue, 2,2-diethoxyacetophenone, 9, 10-phenanthrenequinone, 2-methyl ^•anthraquinone, 2-ethyl anthraquinone, 1-tert-butyl-anthraquinone,

400 1,4-naphthoquinone, isopropylthioxanthone, 2-chlorothioxanthone, 2- isopropyl-thioxanthone , 2-methyl thioxanthone, 2-decylthioxanthone, 2-dodecyl-thioxanthone, 2-methyl- l-[4-(methyl thio)phenyl)]-2- morpholino-propanone-1, combinations thereof and the like. The photoinitiator or combination of photoinitiators is typically utilized in

405 an amount ranging from about 1 to 15, preferably from about 0.5 to 5, percent by weight of the radiation-curable composition. If the radiation-curable composition is cured by exposure to electron beam radiation, a photoinitiator is typically not utilized.

A radiation-curable composition containing the 410 acrylourethane oligomers of the present invention may also contain other optional ingredients known to those skilled in the art of radiation-curable compositions. Examples of additional optional components include inhibitors, monomers, flow control agents, adhesion promoters, flatting agents, pigments, defoamers, stabilizers, 415 anti-yellowing agents, and optical brighteners.

The coating compositions of this invention are prepared by conventional methods such as blending. The compositions can be applied to any surface or substrate capable of receiving the compositions such as wood, metal, fabric or plastic substrates. The 420 coating compositions of the invention are preferably utilized at present to coat vinyl substrates such as those used in floor coverings. The present coating compositions may also be utilized as a coating for other products such as tile, wood flooring, sporting equipment such as baseball bats, cabinetry, counter-tops and furniture. 425 The radiation curable coating compositions of the present invention may be applied to a substrate or surface by brushing, spraying, wiping, dipping, or the like, typically at a film thickness ranging from about 0.2 to 10 mils, preferably from about 0.5 to 3.0 mils. Application can, for example, be by roll coating, curtain coating, flow

430 coating followed by air knife, or airless spray. The polymerization of the radiation-curable composition may be initiated by exposing the coated substrate or surface to any source of actinic radiation at a wavelength within the ultraviolet or visible spectral regions so long as that wavelength overlaps the absorption spectrum of any photoinitiator

435 being utilized. Suitable sources of radiation include mercury, xenon, carbon arc and tungsten filament lamps, sunlight, etc. Exposures may be from less than about 1 second to 10 minutes or more depending upon the amounts of particular polymerizable materials and photoinitiators being utilized and depending upon the radiation source

440 and distance from the source. Generally speaking, the rate of polymerization increases with increasing amounts of photoinitiator at a given light exposure and also increases with increasing light intensity at a given level of photoinitiator. The use of thermal energy during or after exposure to a radiation source will also generally

445 accelerate the curing reaction, and even a moderate increase in temperature may greatly accelerate cure rate. The radiation-curable composition may also be polymerized by exposure to electron beam irradiation in a dosage typically ranging from less than about 1 megarad to 100 megarad or more, preferably ranging from about 2 to

450 10 megarad.

The following examples are provided for the purpose of illustration only and are not intended to limit, in any manner, the scope of the present invention which is defined by the claims. Throughout the examples, the isocyanate content is measured 455 according to ASTM D2572. Equivalent weights of hydroxyl compounds are obtained according to ASTM D4274, Method C.

Example 1

A polyester-modified polydiene/acrylourethane oligomer is prepared by the following procedure. 460 Preparation of Polvester-Modified Polvdiene Polvol

A one liter round-bottom flask with three necks is fitted with a mechanical stirrer, a stopper for sampling, and a special Claisen adapter which accommodates a gas purge line, a thermocouple, and a condenser. The vessel is charged with 72.88 grams of ε-caprolactonf^>

465 (eq. wt. 114) and 677.12 grams of hydroxylated polybutadiene (POLY BL R-45 HT - Elf Atochem North America, Inc., eq. wt. 1061). The components are purged with nitrogen and mixed while a heating bath at 140° C is applied When the contents of the kettle reach 125° C, 0.17 gram of stannous octoate catalyst is added. The reaction is complete

470 in about eight hours. The disappearance of ε-caprolactone can be followed by NMR or chromatography if desired.

Preparation of Polvester-Modified Polvdiene/Acrylourethane Oligomer

A one liter Morton kettle with a four-necked lid is fitted with a mechanical stirrer, a stopper for sampling, and a special Claisen

475 adapter which accommodates a gas purge line, a thermocouple, and a condenser. It is charged with 159.8 grams of the polyester-modified polydiene polyol (eq. wt. 1175) prepared above, 41.0 grams of 4,4'- methylene-bis(cyclohexyl isocyanate), (eq. wt. 132) and 0.06 grams of methoxyhydroquinone antioxidant. The components are purged with

480 nitrogen and mixed while a heating bath at 60° C is applied. When the contents of the kettle reach 58° C, 0.081 gram of butyl tin mercaptide catalyst is added. After 35 minutes, the purge is switched to dry air and 60.0 grams of a reactive diluent (alkoxylated trimethylol propane triacrylate) is added. When the isocyanate content reaches 2.9%, 39.2

485 grams of the olefinically unsaturated compound are added. In this preparation, the olefinically unsaturated compound is the reaction product of equimolar amounts of ε-caprolactone and 2-hydroxyethyl acrylate (eq. wt. 230.3). The reaction is allowed to proceed until the isocyanate content falls below 0.25%. An additional 0.06 grams of

490 methylhydroquinone is mixed into the reaction mixture at this point. Comparative Example 2

A polydiene-based acrylourethane oligomer as disclosed in U.S. Patent No. 4,780,487, is prepared according to the following procedure.

495 A one liter Morton kettle with a four-necked lid is fitted with a mechanical stirrer, a stopper for sampling, and a special Claisen adapter which accommodates a gas purge line, a thermocouple, and a condenser. The reactor is charged with 280.2 grams of hydroxylated polybutadiene (POLY BD R-45 HT - Elf Atochem North America, Inc.,

500 eq. wt. 1061), 105.7 grams of 4,4'-methylene-bis(cyclohexyl isocyanate), (eq. wt. 132), and 0.14 grams of methylhydroquinone antioxidant. The components are purged with nitrogen and mixed while a heating bath at 60° C is applied. When the contents of the kettle reach 56° C, 0.14 grams of butyl tin mercaptide catalyst is added. After 20 minutes, the

505 purge is switched from nitrogen to dry air, and 140.0 grams of a reactive diluent (alkoxylated trimethylol propane triacrylate) is added. When the isocyanate content reaches 4.3%, 174.1 grams of olefinically unsaturated compound (the reaction product of equimolar amounts of ε-caprolactone and 2-hydroxyethyl acrylate, eq. wt. 230.3) is added.

510 The reaction is allowed to continue until the isocyanate content falls below 0.25%. An additional 0.14 grams of methylhydroquinone is mixed into the reaction mixture at this point.

Preparation of Radiation-Curable Coating Compositions

Two radiation-curable coating compositions are prepared by 515 combining the oligomers prepared above with the following ingredients: Formulation 1

Amount in Parts

Ingredient bv Weight (PBW) Polyester-modified polydiene oligomer from 62.50 Example 1

Pentaerythritol tetraacrylate 5.00 Tripropylene glycol diacrylate 22.50 Ethoxylated trimethylol propane triacrylate 10.00 Benzophenone 1.00 Hydroxycyclohexylphenyl ketone 1.00

Formulation 2

Amount in Parts

Ingredient bv Weight (PBW) Polydiene oligomer from Example 2 62.50 Pentaerythritol tetraacrylate 5.00 Tripropylene glycol diacrylate 22.50 Ethoxylated trimethylol propane triacrylate 10.00 Benzophenone 1.00 Hydroxycyclohexylphenyl ketone 1.00

The coatings are formulated by dissolving the benzophenone 520 and hydroxycyclohexylphenyl ketone in the reactive diluents, and then combining the resulting solution with the oligomer. The jars are capped, then shaken on a paint shaker for about 30 minutes, placed in a 60° C oven for about 20 minutes, then shaken again for about 30 minutes. Additional warming and shaking cycles are used if 525 necessary to achieve a unifofm emulsion.

Measurement af Gross Phase Separation

The radiation-curable coating compositions prepared above are placed in cylindrical glass jars and allowed to sit for twelve days.

After this period of time, the gross phase separation of each

530 composition is measured by recording the depth of each layer with a meter scale. Percent separation is calculated as (100 X mm. bottom layer) + total depth. The results are set forth in Table 1.

TABLE 1

Millimeters of Millimeters of Percent top layer bottom layer Separation

Formulation 1 50 1 2

Formulation 2 2A 27 53

Application and Cure of Coating Compositions

535 The compositions are applied to a sheet vinyl substrate to provide 1.5 wet mils of coating. The coated substrate is cured by exposure to ultraviolet radiation supplied by two medium pressure mercury vapor lamps operated at 200 watts per lamp. The cure is conducted under a nitrogen atmosphere, and at a line speed of 30 feet

540 per minute. All compositions are cured in a single pass.

Measurement of Stain and Wear Resistance

The cured coatings are evaluated for stain resistance with the following procedure. Five staining agents are used: iodine, Rit black dye, Kiwi shoe polish, Koppers asphalt sealer (coal tar), and French's

545 mustard. The iodine and Rit dye are applied to the coated vinyl substrate with 1.5 cm squares of lab wiper tissue to prevent running. The other stains are applied without support, in circles with diameters approximately 1.5 cm. The staining agents are allowed to remain on the coated substrate for approximately one hour, and

550 excess material is then removed by wiping with a solvent. Water is used as the solvent for the mustard and Rit dye, while mineral spirits is used as the solvent for the shoe polish and asphalt sealer. Solvent has little effect on iodine. Each stain is rated from 0 to 4, with 0 indicating no stain, and 4 being most severe. The scores for each

555 agent are added, so the worst score a sample can receive is 20, the best is O. Wear resistance of the coated vinyl substrate is evaluate' by measur ng gloss loss in a falling sand abrasion test which is a modification of ASTM D968. The coated sample is measured for initial

560 gloss (60°) in several positions. It is then placed in the falling sand tester and 2000 grams (+/- 0.5 gram) are passed through the instrument. The abraded area is wiped with a dry cloth, then with isopropanol, and the gloss is measured again. Gloss loss is calculated as (100 X (initial gloss - final gloss)) + final gloss. Lower values

565 indicate better performance.

The results of the stain and wear resistance tests are given below in Table 2. Comparative data for commercially available conventional coatings are given to further display the advantage of the invention. 570

TABLE 2

Stain Resistance Gloss Loss

Formulation 1 8 8

Formulation 2 7 20

C:mmercial 1 10 30

Commercial 2 13 22

As can be seen from the above data, coating compositions based on the polyester-modified polydiene/acrylourethane oligomers of t e present invention remain unusually stable during storage and are capable of providing stain and wear resistance which is equivalent to

575 or better than the stain and wear resistance of previously developed acrylourethane-based coating compositions.

Claims

What is claimed is:

580 1. A polyester-modified polydiene/acrylourethane oligomer which is the reaction product of an olefinically unsaturated compound and a polyester-modified polydiene urethane prepolymer.

2. An oligomer according to Claim 1 wherein the olefinically unsaturated compound is selected from the group consisting of

585 2-hydroxylethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxy- propyl acrylate, 3-hydroxypropyl methacrylate, N-hydroxymethyl acrylamide, N-hydroxylmethyl methacrylamide, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, tripropylene glycol monoacrylate, butane diol monoacrylate, glycerine dimeth-

590 acrylate, trimethylol propane dimethacrylate, and the reaction products of polyether glycols and acrylic or methacrylic acid.

3. An oligomer according to Claim 1 wherein the olefinically unsaturated compound is a lactone-acrylate adduct prepared by reacting a lactone with an acrylate or methacrylate acid ester.

595 4. An oligomer according to Claim 3 wherein the lactone has the formula:

wherein R is hydrogen or an alkyl group having from 1 to 12 carbon atoms, x is from 4 to 7 and at least (x - 2) R's are hydrogen.

600 5. An oligomer according to Claim 4 wherein the lactone is ε-caprolactone.

6. An oligomer according to Claim 3 wherein the acrylate or methacrylate acid ester contains from 1 to 3 acrylyl or alpha- substituted acrylyl groups and one or two hydroxyl groups.

7. An oligomer according to Claim 6 wherein the acrylate or 605 methacrylate acid ester is a hydroxyl alkyl acrylate or methacrylate having the formula:

0

CH₂ = C C OR'OH

R'

wherein R' is hydrogen or methyl and R" is a linear or a branched alkylene group having from 2 to 10 carbon atoms.

610 8. An oligomer according to Claim 7 wherein the hydroxyl alkyl acrylate or methacrylate is selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 3- hydroxypentyl acrylate, 6-hydroxynonyl acrylate, 2-hydroxyethyl

615 methacrylate, 2-hydroxylpropyl methacrylate, 3-hydroxypropyl meth¬ acrylate, 2-hydroxybutyl methacrylate, 2-hydroxypentyl methacrylate, 5-hydroxypentyl methacrylate, 7-hydroxyheptyl methacrylate and 5-hydroxydecyl methacrylate.

9. An oligomer according to Claim 7 wherein the hydroxyl 620 alkyl acrylate or methacrylate is 2-hydroxyethyl acrylate or methacrylate.

10. An oligomer according to Claim 1 wherein the polyester- modified polydiene urethane prepolymer is prepared by reacting a polyisocyanate and a polyester-modified polydiene polyol.

625 11. An oligomer according to Claim 10 wherein the polyisocyanate compound is selected from ^"ne group consisting of aliphatic, cycloaliphatic and aromatic polyisocyanates.

12. An oligomer according to Claim 11 wherein the polyisocyanate is selected from the group consisting of toluene-2,4-

630 diisocyanate, 2,2,4- trimethylhexamethylene-l,6-diisocyanate, hexa- methylene-l,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, tri- phenylmethane-4,4',4"-triisocyanate, polymethylene polyphenyl- isocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6- toluene diisocyanate, 1,5-naphthalene diisocyanate, naphthalene- 1,4-

635 diisocyanate, diphenylene-4,4'-diisocyanate, 1,4-cyclohexylene di- methylene diisocyanate, xylene-l,4-diisocyanate, xylene- 1,3-diiso- cyanate, 2,5(or 6)-Bis(isocyanatomethyl)bicyclo[2,2,l]heptane cyclo- hexyl-l,4-diisocyanate, 4,4'-methylene-bis(cyclohexyl isocyanate), 3,3'- dimethyldiphenylmethane-4,4'-diisocyanate, isophorone diisocyanate,

640 m-tetramethyl xylene diisocyanate, and the product obtained by reacting trimethylol propane and 2,4-toluene d isocyanate in a ratio of 1:3.

13. An oligomer according to Claim 12 wherein the polyisocyanate is 4,4'-methylenebis(cyclohexyl isocyanate).

645 14. An oligomer according to Claim 10 wherein the polyester- modified polydiene polyol is prepared by reacting a polydiene polyol and a polyester-forming monomer.

15. An oligomer according to Claim 14 wherein the polydiene polyol is a hydroxylated polymer of a conjugated diene having from

650 about 4 to 12 carbon atoms.

16. An oligomer according to Claim 14 wherein the polydiene polyol is selected from the group consisting of hydroxylated polybutadiene, hydroxylated 2,3-dimethylbutadiene, hydroxylated poly- isoprene, hydroxylated polyhexadiene, hydroxylated polyheptadiene,

655 hydroxylated polyoctadiene and the hydrogenated analogs thereof.

17. An oligomer according to Claim 16 wherein the polydiene polyol is hydroxylated polybutadiene.

18. An oligomer according to Claim 14 wherein the polyester- forming monomer is a compound capable of forming a polyester

660 linkage with a hydroxyl group of the polydiene polyol through a condensation reaction.

19. An oligomer according to Claim 18 wherein the polyester- forming monomer is selected from the group consisting of reactive- lactones, hydroxyl-func onal carboxylic acids, and hydroxyl- 665 functional carboxylic acid esters.

20. An oligomer according to Claim 19 wherein the reactive lactones are selected from the group consisting of ε-caprolactone; β-propiolactone; lactide; β-butyrolactone; α,α-bis(chloromethyl)propio- lactone; δ-valerolactone; α,β,γ-trimethoxy-δ-valerolactone; 1,4-dioxane-

670 2-one; glycolide; l,4-dithiane-2,5-dione; trimethylene carbonate; neopentylene carbonate; ethylene oxalate; propylene oxalate; β-methyl- ε-isopropyl-ε-caprolactone; lactone of 4^hydroxycyclohexanecarboxylic acid; cis-disalicylide; di-ocresotide; and trisalicylide.

21. An oligomer according to Claim 20 wherein the reactive 675 lactone is ε-caprolactone.

22. An oligomer according to Claim 19 wherein the carboxylic acids and esters are selected from the group consisting of 2- hydroxyl benzoic acid, 3-hydroxyl benzoic acid, 4-hydroxyl benzoic acid, lactic acid, 11-hydroxyl undecanoic acid, 9-hydroxyl nonanoic

680 acid, and esters thereof.

23. A radiation-curable composition comprising a polyester- modified polydiene/acrylourethane oligomer and a reactive diluent system.

24. A composition according to Claim 23 wherein the reactive 685 diluent system comprises reactive diluents selected from the group consisting of unsaturated addition-polymerizable monofunctional acrylic monomers, unsaturated addition-polymerizable polyfunctional acrylic monomers, olefinically unsaturated compounds, addition polymerizable vinyl monomers, and combinations thereof.

690 25. A composition according to Claim 24 wherein the reactive diluents a ^a selected from the group consisting of isobornyl acrylate, phenoxyethyl acrylate, isodecyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, stearyl acrylate, 2-phenoxy acrylate, 2-methoxyethyl acrylate, lactone

695 modified esters of acrylic and methacrylic acid, methyl methacrylate, butyl acrylate, isobutyl acrylate, methacrylamide, allyl acrylate, tetrahydrofuryl acrylate, n-hexyl methacrylate, 2-(2-ethoxy- ethoxy)ethyl acrylate, n-lauryl acrylate, 2 -phenoxyethyl acrylate, glycidyl methacrylate, glycidyl acrylate, acrylated methylolmelamine,

700 2-(N,N-diethylamino)-ethyl acrylate, neopentyl glycol diacrylate, alkoxylated neopentyl glycol diacrylate, ethylene glycol diacrylate, hexylene glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, penta-erythritol di-, tri-, or tetraacrylate, trimethylolpropane triacrylate, alkoxylated

705 trimethylolpropane triacrylate which contains from 2 to 14 moles of either ethylene or propylene oxide, triethylene glycol diacrylate, tetraethylene glycol diacrylate, diacrylate of bisphenol-A diepoxide, polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4- butanediol diacrylate, 1,6-hexanediol diacrylate, other diacrylates of

710 butane diols or pentane diols or hexane diols, polyethylene glycol diacrylate, any corresponding methacrylates thereof, and combinations thereof.

26. A composition according to Claim 25 wherein the reactive diluents are selected from the group consisting of tripropylene glycol

715 diacrylate, ethoxylated trimethylolpropane triacrylate, and penta¬ erythritol tetraacrylate.

27. A composition according to Claim 23 further comprising a photoinitiator.

28. A composition according to Claim 27 wherein the 720 photoinitiator is selected from the group consisting of benzophenone, benzoin, acetophenone, benzoin methyl ether, Michler's ketone, benzoin butyl ether, xanthone, thioxanthone, propiophenone, fluorenone, carbozole, diethyoxyacetophenone, the 2-, 3- and 4- methylacetophenones and methoxyacetophenones, the 2- and 3-

725 chloroxanthones and chlorothioxanthones, 2-acetyl-4-methylphenyl acetate, 2,2'-dimethyoxy-2-phenyl-acetophenone, hydroxycyclohexyl¬ phenyl ketone, benzaldehyde, fluorene, anthraquinone, triphenyl- amine, 3- and 4-allylacetophenone, p-diacetylbenzene, 3-chloro-2- nonylxanthone, 2-chlorobenzophenone, 4-methoxybenzophenone,

730 2,2',4,4'-tetrachlorobenzophenone, 2-chloro-4'-methylbenzophenone, 4-chloro-4'-methylbenzophenone, 3-methylbenzophenone, 4-tert-butyl- benzophenone, isobutyl ether, benzoic acetate, benzil, benzilic acid, amino benzoate, methylene blue, 2,2-diethoxyacetophenone, 9,10- phenanthrenequinone, 2-methyl anthraquinone, 2-ethyl anthra- 735 quinone, 1-tert-butyl-anthraquinone, 1,4-naphthoquinone, isopropyl- thioxanthone, 2-chlorothioxanthone, 2-isopropyl-thioxanthone, 2-methylthioxanthone, 2-decyl-thioxanthone, 2-dodecyl-thioxanthone, 2-methyl- l-[4-(methyl thio)phenyl)]-2-morpholino-propanone-l, and combinations thereof.

740 29. A composition according to claim 23 further comprising one or more additional components selected from the group consisting of inhibitors, monomers, flow control agents, adhesion promoters, flatting agents, pigments, defoamers, stabilizers, anti-yellowing agents, and optical brighteners.