WO1995000560A1

WO1995000560A1 - Reactive polymers

Info

Publication number: WO1995000560A1
Application number: PCT/US1994/007000
Authority: WO
Inventors: James Wayne Taylor; Martha Jean Collins; David Robinson Basset
Original assignee: JOHNSON, Karen, L.
Priority date: 1993-06-23
Filing date: 1994-06-20
Publication date: 1995-01-05
Also published as: AU7248794A

Abstract

This invention relates to reactive polymers, e.g., aqueous emulsion polymers, having pendant flexible or dangling side chains prepared from ethylenically unsaturated epoxides, e.g. epoxide (meth)acrylates, or from imines and ethylenically unsaturated epoxides, e.g., epoxide (meth)acrylates, or from imines and ethylenically unsaturated isocyanates. The reactive polymers contain ethylenic unsaturation near the surface or in the surface area of the particles that form the polymers, the ethylenic unsaturation being connected to the polymer through the pendant flexible or dangling side chains. This invention also relates to the process for preparing the reactive polymers, to crosslinkable formulations based on the reactive polymers, and to thermoplastic and crosslinked films prepared from the reactive polymers. The reactive polymers are useful as decorative and functional coatings, inks, adhesives, textile coatings and sealants.

Description

REACTIVE POLYMERS

Related Applications

The following are related, commonly assigned applications, filed on an even date herewith:

U.S. Patent Application Serial No. (D-16894); U.S. Patent Application Serial No. (D-17043); U.S. Patent Application Serial No. (D- 16967); all of which are incorporated herein by reference.

Rrief SinTiTtinr of the Invention

Technical Field

This invention relates to reactive polymers, e.g., aqueous emulsion polymers, having pendant flexible or dangling side chains prepared from ethylenically unsaturated epoxides, e.g., epoxide (meth)acrylates, or from imines and ethylenically unsaturated epoxides, e.g., epoxide (meth)acrylates, or from imines and ethylenically unsaturated isocyanates. The reactive polymers contain ethylenic unsaturation near the surface or in the surface area of the particles that form the polymers, the ethylenic unsaturation being connected to the polymer through the pendant flexible or dangling side chains. This invention also relates to the process for preparing the reactive polymers, to crosslinkable formulations based on the reactive polymers, and to thermoplastic and crosslinked films prepared from the reactive polymers. The reactive polymers are useful as decorative and functional coatings, inks, adhesives, textile coatings and sealants.

Background of the Invention

Aqueous emulsion polymers or latexes in both clear and pigmented form are well-known, widely-used articles of commerce. Examples of these uses include interior and exterior architectural coatings, general metal coatings, adhesives, and the like. The latexes are formed by aqueous emulsion polymerization of monoethylenically unsaturated monomers as styrene, butyl acrylate, methyl methacrylate, vinyl acetate, acrylic acid, glycidyl acrylate, 2- hydroxyethyl acrylate, and similar compounds. When ethylenically unsaturated monomers that contain a functionality other than unsaturation, such as the carboxyl group in acrylic acid, and the hydroxyl group in 2-hydroxyethyl acrylate, are used, there is a propensity for these groups to be found at or near the surface of the emulsion particles because of the affinity of the groups for the aqueous environment. In addition, techniques for increasing the amount of any non-water reactive functional group near the surface of the emulsion particles are known to those skilled in the art of emulsion polymerization. Illustrative of such techniques is the production of a core and shell latex in which the core of the particles has a given composition that may contain a small amount of the functional groups or be devoid of them and the shell or outer layers of the particle have a different composition which may be rich in the functional groups, and the like.

There is a need for products that have improved, lower initial molecular weight characteristics, improved adhesion, and products that will crosslink under ambient conditions or low to moderate temperatures in the presence of air.

Disclosure of the Invention

This invention relates in part to a polymer having one or more pendant flexible side chains connected thereto, wherein said pendant flexible side chains contain ethylenic unsaturation and are connected to said polymer by (1) an ester linkage or by (2) an ester linkage and an amine linkage or by (3) an ester linkage and a urea linkage, said ester linkage in (1) formed by the reaction of an ethylenically unsaturated epoxide with a carboxylic acid group on said polymer, said ester linkage in (2) and (3) formed by the reaction of an imine with a carboxylic acid group on said polymer to form an amine group connected to the polymer, said amine linkage in (2) formed by the reaction of an ethylenically unsaturated epoxide with said amine group, and said urea linkage in (3) formed by the reaction of an ethylenically unsaturated isocyanate with said amine group.

This invention also relates in part to a process for preparing a polymer having one or more pendant flexible side chains connected thereto comprising:

(a) preparing a precursor polymer having carboxyl group functionality from one or more ethylenically unsaturated monomers;

(b) optionally post reacting the precursor polymer with one or more ethylenically unsaturated epoxides;

(c) post reacting the precursor polymer of step (a) with one or more imines;

(d) post reacting the polymer of step (c) with one or more ethylenically unsaturated epoxides or one or more ethylenically unsaturated isocyanates; and

(e) optionally recovering the step (b) or (d) polymer and redissolving it in an organic solvent.

It has been found that ethylenic unsaturation of various types can be formed on, in, or near the surface of polymer particles that contain free, reactive carboxylic acid functionality by first preparing a precursor polymer and then post reacting it with one or more ethylenically unsaturated epoxides, e.g., epoxide (meth)acrylates, or one or more suitable imines containing a functional group that will react with all or a portion of the free, reactive carboxyl functionality on the precursor polymer particle and then post reacting the amine group with one or more ethylenically unsaturated epoxides or one or more ethylenically unsaturated isocyanates. When the final post reactant is used, it will contain an ethylenic unsaturation group that can air dry or force dry into a crosslinked, solvent resistant coating with broad utility characteristics. Air dry means to cure the liquid coating into a solid film by allowing it to remain under ambient conditions for a period of time sufficient to effect solidification. Force dry means to cure the liquid coating into a solid film by exposing it to a thermal source such as an oven, to an actinic radiation source such as ultraviolet light, as electron beams, as lasers, and the like with or without a predrying step under ambient conditions to remove water, solvent, or other carrier. For purposes of this invention, ethylenic unsaturation shall include all permissible compounds, groups or substituents having at least one carbon-carbon double bond including, for example, (meth)acrylates, vinyls, allyls, alkenes, and the like.

In an embodiment of this invention, the post modified polymer containing ethylenic unsaturation is recovered from the aqueous environment, dissolved in an organic solvent, and applied to a substrate to effect air-cure crosslinking. In specific embodiments of this invention, the water-borne polymer particles can be crosslinked with free radicals generated from an actinic energy source such as an electron beam or by formulation with a free radical-generating photoinitiator and, if necessary, a synergist, and exposed to an ultraviolet light source such as sunlight, mercury vapor lamps, xenon lamps, etc.

In another embodiment of the invention, the polymer precursor containing free, reactive carboxyl functionality can be recovered from the aqueous media and dissolved in an organic solvent or can be prepared in an organic solvent. The polymer in organic solvent can be modified by post reaction with one or more of the above described reactants for aqueous systems to form a polymer with pendant flexible chains having ethylenic unsaturation connected thereto that can be crosslinked under ambient, air-cure conditions or radiation-cure conditions.

In a further embodiment of the invention, the post modified polymers containing ethylenic unsaturation neat or formulated with photoinitiator and/or other radiation-reactive chemicals is recovered as a solid, uncrosslinked film by removal of either the aqueous or organic solvent media. The solid film is then used as a photoresist in the manufacture of printed circuit boards or other article by selective exposure to radiation. Selective exposure is provided by a mask through which radiation does not penetrate.

The reactive polymers of the invention can be used in a variety of ways including but not limited to clear, colored, filled, or pigmented crosslinked latexes, water-borne alkyds, solvent-borne alkyds, radiation curable systems, and the like. Illustrative of generalized utility areas are coatings for metal, paper, plastics, wood, and masonry; inks; adhesives; binding agents for concrete; photoresists; and the like. Among the specific coating end uses that can be mentioned are interior and exterior architectural coatings, can coatings, office and home furniture coatings, pipeline coatings, sign coatings, maintenance coatings, business machine coatings, functional and decorative automotive coatings, textile coatings, conformal coatings, electrical and electronic coatings and the like.

Detailed Description

Carboxyl group functionalized polymer particles can be reacted with an ethylenically unsaturated epoxide to form a free ethylenically-unsaturated terminated, pendant flexible side chain Hnked to the polymer particle through an ester linkage, or reacted with first an imine, in which case the reaction takes place with a carboxylic acid group to form a free amine group connected to the polymer particle by an ester linkage, and then in a second reaction the amine group is post reacted with:

(1) an ethylenically unsaturated epoxide, e.g., epoxide (meth)acrylate group, to form a free ethylenically unsaturated terminated, pendant flexible side chain connected to the polymer particle through an amine linkage, or

(2) an ethylenically unsaturated isocyanate to form a free vinyl-terminated or (meth)acrylate-terminated, pendant flexible side chain that is connected to the polymer particle through a urea linkage. For purposes of this invention, the term "ester linkage" is contemplated to include all permissible linkages resulting (i) from the reaction of an ethylenically unsaturated epoxide with a carboxylic acid group on the polymer which links an ethylenically unsaturated terminated, pendant flexible side chain to the polymer or (ii) from the reaction of an imine with a carboxylic acid group on the polymer which forms a free amine group connected to the polymer. For purposes of this invention, the term "amine linkage" is contemplated to include all permissible linkages resulting from the reaction of an ethylenically unsaturated epoxide with a free amine group on the polymer which links an ethylenically unsaturated terminated, pendant flexible side chain to the polymer. For purposes of this invention, the term "urea linkage" is contemplated to include all permissible linkages resulting from the reaction of an ethylenically unsaturated isocyanate with a free amine group on the polymer which links an ethylenically unsaturated terminated, pendant flexible side chain to the polymer.

The polymers having carboxyl group functionality can be prepared from a variety of monoethylenically unsaturated monomers including, for example, acrylates and methacrylates (both referred to herein as (meth)acrylates); vinyl esters; vinyl aromatic, cycloaliphatic, and heterocycles; hydroxyalkyl (meth)acrylates and their derivatives; vinyl halogens and vinylidine halogens; alkenes and substituted alkenes; nitriles; and vinyl ethers. If desired, minor amounts of di- or triethylenically unsaturated monomers can be used if they do not unduly interfere with the polymerization process by causing excessive crosslinking and unusable polymer formation. Various carboxyhc acid monomers can be used, such as acrylic acid, methacrylic acid, ethacrylic acid, alpha-chloroacrylic acid, crotonic acid, fumaric acid, άtraconic acid, mesaconic acid, itaconic acid, maleic acid and the like including mixtures thereof. Illustrative of the (meth)acrylates are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylates, butyl (meth)acrylates, pentyl (meth)acrylates, hexyl (meth)acrylates, heptyl (meth)acrylates, octyl (meth)acrylates, nonyl (meth)acrylates, decyl (meth)acrylates, and the like. Illustrative of the vinyl esters are vinyl acetate, vinyl propionates, vinyl butyrates, vinyl pivalates, vinyl hexanoates, vinyl hepanoates, vinyl octanoates, vinyl isovalerate, vinyl 2-ethylhexanoate, vinyl benzoates, vinyl crotonate, vinyl laurates, vinyl myristate, vinyl linoleate, vinyl Unolenate, vinyl cinnamate, vinyl stearates, vinyl oleate, vinyl napthanoates, vinyl cyclopentanoates, vinyl versatates, vinyl salicylate, monovinyl adducts of difunctional or higher functional carboxylic acids as monovinyl adipate. Illustrative of the vinyl aromatic, cycloaliphatic, and heterocycles are styrene, vinyl cyclohexane, vinyl cyclopentane, vinyl toluene, vinyl anthracenes, 3- vinyl benzyl chloride, 4-vinyl biphenyl, 4-vinyl-l-cyclohexene, vinyl cyclooctane, 2-vinyl naphthalene, 5-vinyl-2-norbornene, 1-vinyl imidazole, 2-vinyl pyridine, 4-vinyl pyridine, l-vinyl-2-pyrrolidinone, 9- vinyl carbazole, 3-vinylbenzyl chloride, and the like. The hydroxyalkyl (meth)acrylates and their derivatives include 2-hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), ethylene oxide and propylene derivatives of HEA and HPA containing from 1 to about 20 moles of the alkylene oxide, caprolactone acrylates which are epsilon-caprolactone derivatives of HEA and HPA containing from 1 to about 6 moles of epsilon-caprolactone, carboxylic acid terminated adducts of HEA and HPA and the alkylene oxide and caprolactone derivatives of HEA and HPA, and the like. Illustrative of the vinyl halogens and vinylidine halogens are vinyl chloride, vinylidine chloride, vinyl fluoride, vinylidine fluoride, and the like. Illustrative of the alkenes and substituted alkenes are ethylene, propylene, butenes, pentenes, hexenes, heptenes, octenes, nonenes, decenes, 4-chloro-l-butene, 4, 6- dichloro-1-hexene, 5-fluoro-2-hexene, and the like. Illustrative of the nitriles are acrylonitrile, methacrylonitrile, and the like. Illustrative of the vinyl ethers are methyl vinyl ether, ethyl vinyl ether, propyl vinyl ethers, butyl vinyl ethers, pentyl vinyl ethers, hexyl vinyl ethers, hepty vinyl ethers, octyl vinyl ethers, 2-methyl-l-butyl vinyl ether, and the like. The polymers are prepared by conventional techniques as exemplified herein and as are known to those skilled in the art of polymerization. The molecular weight of the copolymers making up the polymer particles can vary over wide ranges of average molecular weight and can have number-average molecular weights of from about 1000 to about 1,000,000 or more with a distribution of molecular weights existing. Since film formation of aqueous emulsion polymers conventionally takes place by particle coalescence in which the outer regions of the particles come together and interact to form the final film, it is preferable that the polymer particles of this invention contain a major quantity of the functional groups in, at or near the surface (i.e., the surface region) of the particles, though it is realized that some of the functional groups may be positioned within the interior of the particles. Although the number of copolymers in each polymer particle is indeterminate since particle size and copolymer molecular weight will vary, it is important that, on the average, carboxyl functionality exist on a majority of any copolymer molecules and that at least some of the functionahty be found in the surface region or related region so it can react with the post reaction reactants. Other functional groups such as hydroxyl, etc., may also be present in the carboxyl functional polymer, i.e., precursor polymer, used in this invention.

Illustrative of the imines that can be used to produce the polymer particles containing amine termination (the first step of modifying the precursor polymer particles for post reaction to produce the polymers of the invention) are alkylene imines, such as ethylene imine, propylene imine, butylene imine, hexylene imine, 1,2- dimethylethylene imine, 1,1,2-trimethylethylene imine, cyclohexylene imine, and the like. Mixtures of the various alkylene imines may be used for the purposes of this invention. Both substituted and unsubstituted imines may be used for purposes of this invention.

Illustrative of the ethylenically unsaturated epoxides that can be used to react with the carboxyl group functionalized polymers or with the amine-ter inated polymer particles are the epoxide (meth)acrylates such as glycidyl (meth)acrylates, 2,3-epoxypropyl (meth .acrylate, allyl glycidyl (meth)acrylates, and the like. When the ami ne-terminated polymer particles are prepared in such a manner that less than an equivalent amount of imine is used so that residual carboxylic acid groups remain, ethylenically unsaturated cycloaliphatic epoxides can be used. Illustrative of the epoxides that can be used to react with the carboxyl containing polymer particles are the 3,4- epoxycyclohexane (meth)acrylates . The 3,4-epoxycyclohexane (meth)acrylates can be prepared by (1) reacting tetrahydrobenzyl alcohol or tetrahydrobenzyl alcohol that has been first reacted with one or more appropriate alkylene oxide and/or epsilon-caprolactone, (2) reacting the alcohol or alcohol adduct with (meth)acrylic acid in an esterification reaction or with a lower alkyl (meth)acrylate such as methyl (meth)acrylate in a transesterification reaction to form 3- cyclohexene (meth)acrylate, and (3) epoxidizing the 3-cyclohexene (meth)acrylate to the 3,4-epoxycyclohexane (meth)acrylate. In a particular embodiment of this invention, the polymer particles are made by reacting 3,4-epoxycyclohexane (meth)acrylates with polymer particles. Mixtures of various ethylenically unsaturated epoxides may be used for purposes of this invention. Both substituted and unsubstituted ethylenically unsaturated epoxides may be used for purposes of this invention.

Illustrative of the ethylenically unsaturated isocyanates that can be used to react with either the polymer particles (containing hydroxyl functionality) or the amine-terminated polymer particles are the isocyanato alkyl (meth)acrylates such as 2-isocyanatoethyl methacrylate, 3-isocyanatopropyl methacrylate, and the like; the monoisocyanates prepared from diolefins such as the dialkylidene aryls that produce compounds such as l-(l-isocyanato-l-methyl ethyl )-3-(l- methyl ethenyl) benzene (p-TMI), l-(l-isocyanato-l-methyl ethyl)-4-(l- methyl ethenyl) benzene (m-TMI),l-(l-isocyanato-l-methyl propyl)-3- (1-methyl propenyl) benzene, l-(l-isocyanato-l-methyl propyl)-4-(l- methyl propenyl) benzene, l-(l-isocyanato-l-methyl propyl)-4-(l- methyl ethenyl) benzene, l-(l-isocyanato-l-ethyl)-3-(l-ethenyl) benzene, l-(l-isocyanato-l-ethyl)-4-(l-ethenyl) benzene, and the like. Methods for manufacture of such ethylenically unsaturated isocyanates can be found in U.S. Patent No. 2,718,516, U.S. Patent No. 2,821,544, U.S. Patent No. 4,377,530 and U.S. Patent No. 4,439,616 and certain of the isocyanates are commercially available. Mixtures of various ethylenically unsaturated isocyanates may be used for purposes of this invention. Both substituted and unsubstituted ethylenically unsaturated isocyanates may be used for purposes of this invention.

In an embodiment of this invention, initial aqueous emulsions used to prepare aqueous emulsion polymers of this invention have an initial pH of about 2.0 to 10.5 and contain about 0.05 to 20% or more of carboxylic acid functionality, preferably an initial pH of 3.5 to 9.0 and contain from about 0.1% to 15% carboxylic acid functionahty, and are prepared at about 40°C to about 100°C for about 6 to 48 hours, preferably at about 60 °C to about 90 °C for about 10 to about 24 hours under atmospheric pressure or superatmospheric pressure of about 15 psig to about 100 psig.

The post reactions leading to the reactive polymers of this invention are carried out at a temperature of from about 0°C to about 100°C, preferably from about 20°C to about 90° for about 30 minutes to 24 hours or more under atmospheric or superatmospheric pressure of about 15 psig to about 100 psig.

Although not essential, a stoichiometric deficiency of the ethylenically unsaturated epoxide or alkylene imine may be employed in order to leave some carboxyl functionality in the polymer. Excess epoxide or imine is generally avoided since it introduces residual unpolymerized monomer which is undesirable. At least about 0.5% of the ethylenically unsaturated epoxide or alkylene imine, based on the weight of the polymer, is used. Based on the arid content of the precursor polymer, it is preferred to consume at least 5%, preferably from 10% to about 90%, of the arid (carboxyl) by reaction with the ethylenically unsaturated epoxide or alkylene imine. As indicated above, other functional groups such as hydroxyl, amine, etc., may be present in the carboxyl functional polymers, i.e., precursor polymers, used in this invention. Other permissible post reactions may be carried out in a sequential manner so there is no adverse interaction of the reactants used for the post reaction of this invention. Illustrative of other such post reactions include, for example, (1) reaction with a carbodiimide (meth)acrylate wherein reaction takes place with carboxyl groups on the precursor polymer particle; (2) reaction with an ethylenically unsaturated isocyanate wherein reaction takes place with hydroxyl groups on the precursor polymer particle to form free vinyl groups connected to the particle with urethane linkages; (3) reaction with an ethylenically unsaturated aziridine wherein reaction takes place with carboxyl groups on the precursor polymer particle; and the like. Both substituted and unsubstituted post reactants may be used for purposes of this invention. Suitable other post reactions which may be employed herein include those disclosed in U.S. Patent Application Serial No. (D- 16967), U.S. Patent Application Serial No. (D-17043) and U.S. Patent Application Serial No. (D-16894), all of which are incorporated herein by reference. This invention is not intended to be limited in any manner by the number or combination of permissible post reactions.

The reactive polymers, e.g., aqueous emulsion polymers, of this invention can be used in a variety of ways illustrative of which are as air-dry coatings that will increase in molecular weight presumably through crosslinking by reaction with atmospheric oxygen and/or incidental radiation under ambient conditions without the use of heavy metal catalysts known as drier salts, though such catalysts may be optionally included in coating formulations if desired; as thermally crosslinkable coatings when formulated with peroxides that will break down and cause crosslinking to take place through the ethylenic unsaturation; as radiation curable coatings, preferably in the presence of free-radical generating photoinitiators of either the homolytic fragmentation type or the hydrogen abstraction type which are usually 12

used in combination with a nitrogen-containing synergist when ultraviolet light is used as the radiation source; as solvent reduced coatings in which relatively large quantities of solvent, i.e., more than flexibilizing or plasticizing quantities, are added to the formulation before application to a substrate; and the like.

The reactive polymers of this invention may be used alone or in combination with other systems illustrative of which are aqueous emulsions, water reducible alkyds, solutions of polymers, radiation- curable (meth)acrylates or epoxides, unsaturated fatty acid derivatives, linseed oil, soybean oil, tall oil, and the like. In an embodiment of this invention, aqueous alkyds having molecular weights of from about 500 to 5000 are prepared by adding chain transfer agents to the emulsion polymers during polymerization. In another embodiment of this invention, the reactive polymers of this invention are recovered as a solid, redissolved in an organic solvent, and formulated into solvent- borne coatings, particularly high solids alkyd coatings when low molecular weight polymers are formed in the emulsion process. Suitable solvents are polar in nature illustrative of which are esters, ketones, esters of lactic acid; ethylene oxide glycol ethers as ethylene glycol monomethyl ether, ethylene glycol and diethylene glycol monoethyl ethers, ethylene glycol and diethylene glycol monopropyl ethers, ethylene glycol and diethylene glycol monobutyl ethers, and et ylene glycol and diethylene glycol monohexyl ethers; propylene oxide glycol ethers such as propylene glycol and dipropylene glycol monomethyl ethers, propylene glycol and dipropylene glycol monopropyl ethers, propylene glycol and dipropylene glycol monobutyl ethers, propylen glycol monobutyoxyethyl ether; toluene, methyl ethyl ketone, xylene, dimethylfoπnamide, ethyl acetate, butyl acetate, tetrahydrofuran, 1,1,1-trichloroethane, cyclohexanone, hydroxyethers, and the like. If desired, these solvents may be used in combination with aliphatic hydrocarbons, aromatic hydrocarbons, super critical carbon dioxide, and the like. When polymers with glass transition temperatures greater than room temperature are formed, film forming agents or plasticizers of various types may be incorporated into the formulations. Such plasticizers may be (1) of a nonreactive nature, illustrative of which are the various esters, ketones, hydroxy ethers, and the like which may be fugitive in nature when they have low molecular weight and are lost via evaporation or may be retained by the dry film when they have relatively high molecular weight; (2) of a reactive nature and contain ethylenic unsaturation which reacts with the unsaturation in the polymers of the invention and thus become incorporated into the final film, illustrative of which are diethylene glycol diacrylate, ethylene glycol diacrylate, divinyl adipate, disiopropenyl adipate, divinyl succinate, vinyl crotonate, diallyl phthalate, urethane acrylates, acrylated epoxides, timethylol propane triacrylate, pentaerythritol triacrylate and tetraacrylate, and the like; or (3) a mixture of nonreactive and reactive plasticizers.

Optional heavy metal driers that may be incorporated into the coatings to promote curing. These driers are metal salts of organic acids illustrative of which acids are tall oil fatty acids, ethylhexanoic acid, neodecanoic acids, naphthenic adds, and the like. Illustrative of typical metals used for air- or ambient-dry systems are cobalt, zirconium, and manganese, and the like, and for heat-cure coatings are iron, manganese, cobalt, cerium, and the Uke. Auxiliary driers include lead, barium, calcium, zirconyl (ZrO-) , zinc, and the like. If desired, mixtures of the various driers can be used.

Illustrative of the peroxides or compounds that will generate oxygen when heated that can be used in the thermally curable coating compositions of this invention are benzoyl peroxide, t-butyl peroxybenzoate, dϋsopropyl peroxide, and the like. These compounds are used in an amount of about 0.05% to about 5%, preferably from about 0.1% to about 2.5%. It is known to those skilled in the art of these compounds that the cure temperature and decomposition temperature of any chosen compound must be properly considered when they are used.

Illustrative of the homolytic fragmentation-type photoinitiators used in the photocurable coating compositions are 2,2- diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetopheneone, 1- hydroxycyclohexylphenyl ketone, acetophenone, and the like. Illustrative of the hydrogen abstraction-type photoinitiators are benzophenone, benzophenone derivatives, 2-chlorothioxanthone, isopropylthioxanthone, fluorenone, benzil, 9,10-anthraquinone, •camphor quinones, 1,3,5-triacetylbenzene, 3-ketocoιmιarines, acridone, bis-(4,4'-d__methyla____ino)benzophenone, and the Hke. Illustrative of the synergists useful in combination with the hydrogen abstraction-type photoinitiators are amine, amides, urethanes or ureas with a hydrogen- bearing carbon atom in the alpha position to the nitrogen group among which one can mention dimethylethanol amine, triethyl amine; primary, secondary, and tertiary amine-terminated poly (propylene oxide) polyols as well urea and urethane derivatives of such polyols, and the Hke.

Although many of the reactive polymers of this invention can be cured alone with or without added photoinitiator when exposed to ultraviolet light, they may be combined with one or more other radiation-polymerizable ethylenically unsaturated compounds such as substituted and unsubstituted (meth)acrylates. Illustrative of the (meth)acrylates suitable for use in the radiation curable compositions of the invention are the esters of (meth)acrylic acid with monohydric and polyhydric compounds among which one can mention ethyl, butyl, hexyl, octyl, decyl, and the Hke (meth)acrylates; neopentyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate and tetra(meth)acrylate, caprolactone (meth)acrylates which are adducts of 1 to 10 moles of epsilon- caprolactone and a hydroxylalkyl (meth)acrylate, alkoxylated (meth)acrylates, glycerol (meth)acrylates, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2,2-dimethyl-3- hydroxypropyl-2,2-dimethyl-3-hydroxypropionate di(meth)acrylate, isobornyl (meth)acrylate, tripropylene glycol di(meth)acrylate, unsaturated polyesters, 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3- hydroxypropionate di(meth)acrylates as well as alkoxylated versions of such di(meth)acrylates, urethane (meth)acrylates, (meth)acrylated epoxides, (meth)acrylated linseed oil, (meth)acrylated soybean oil, (meth)acrylated polybutadiene, and the Hke. In addition, the formulations may contain N-vinyl pyrrolidone, divinylbenzene, and the Hke.

The reactive polymers, e.g., aqueous emulsions, of this invention can be formulated with a variety of vinyl esters alone or in combination with other radiation-polymerizable ethylenically- unsaturated compounds in the photocurable compositions of this invention. Illustrative of the vinyl esters are vinyl 2-ethylhexanoate, vinyl benzoate, vinyl isovalerate, vinyl nonylates, vinyl neononanoate, vinyl neodecanoate, vinyl myristate, vinyl oleate, vinyl linoleate, vinyl abietate, divinyl adipate, divinyl oxalate, divinyl succinate, divinyl fumarate, divinyl maleate, diisopropenyl adipate, trivinyl mellitate, trivinyl citrate, 1, 2, 4-trivinyl benzenetricarboxylate, tetravinyl mellophanate, 3,3',4,4'-tetravinyl benzophenonetetracarboxylate, and the Hke. Such vinyl ester can also be used as reactive flexibizers/plasticizers in other non-photocurable coating compositions of the invention.

The photopolymerization is carried out by exposing the uncured - ..m or coating to Hght radiation which is rich in short wave radiation. Particularly useful is radiation of about 200 to 450 nanometers in wavelength. lUustrative of appropriate light sources are low-pressure, medium pressure, and high-pressure mercury vapor lamps as weU as lamps of this type that have been doped to exclude selected wavelengths; xenon and other flash-type lamps; lasers operating in the above Hsted wavelength range; sunHght, and the like. Other sources of radiant energy such as electron beams, gamma radiation, X-rays, and so on can also be used. Any permissible conventional additives, processing aids, etc. may be employed in conventional amounts in the compositions and processes of this invention. This invention is not intended to be limited in any manner by any permissible additives, processing aids, and the Uke.

The coating compositions of the invention are applied to appropriate substrates as thin films by a variety of processes illustrative of which are roU coating, dip coating, spray coating, brushing, flexographic, lithographic, and offset-web printing processes, and the Uke.

As used herein, the term "substituted" is contemplated to include all permissible substituents of organic compounds unless otherwise indicated. In a broad aspect, the permissible substituents include acyclic and cycHc, branched and unbranched, carbocycHc and heterocycHc, aromatic and nonaromatic substituents of organic compounds. lUustrative substituents include, for example, alkyl, alkyloxy, aryl, aryloxy, hydroxy, hydroxyalkyl, amino, aminoalkyl, halogen and the like in which the number of carbons can range from 1 to about 20 or more, preferably from 1 to about 12. The permissible substituents can be one or more and the same or different for appropriate organic compounds. This invention is not intended to be limited in any manner by the permissible substituents of organic compounds.

The invention is illustrated by certain of the foU owing examples.

Glossary of Terms and Compounds

Gel Fraction - The gel fraction or gel content is the amount of material that is insoluble when a given mass of the cured coating is extracted with tetrahydrofuran (THF) for 18 houre at room temperature. The extracted film is removed from the THF, rinsed with fresh THF, and dried at 110°C for one hour. The gel fraction, expressed as a percentage, is calculated with the foUowing expression. Gel Fraction = (1 - ((Weight of original film - Weight extracted film ./(Weight of original film)) x (100%)

Gloss, 20° - ASTM D 523

Gloss, 60° - ASTM D 523

Surfactant 1 - A sodium dioctyl sulfosuccinate anionic surfactant commercially available from American Cyanamid Company under the designation Aerosol® OT-75.

Surfactant 2 - A 70% solution of nonyl phenol-based alkylene oxide nonionic surfactant in water commercially available from Union Carbide Chemicals and Plastics Company Inc. under the designation Tergitol® NP-40.

Example

Prepara ion A

Preparation of a core and shell aαueous emulsion A glass reactor equipped with a stirrer, thermometer, nitrogen inlet and outlet, and feeding ports was charged with 986.43 grams of deionized water, 1.07 grams of Surfactant 1, and 1.43 grams of Surfactant 2. A nitrogen purge was started, and the contents of the reactor were heated to 80°C while stirring at 400 revolutions per minute (rpm). To form the core of the aqueous emulsion particles, after temperature was reached, 50 grams of Feed 1, Table 1, were added along with a mixture containing 3.0 grams of potassium persulfate dissolved in 147 grams of deionized water and stirred for 5 minutes. Table 1. Feed 1

Then, with the temperature maintained at 80°C, the remainder of Feed 1 was added over a 190 minute period. Immediately after Feed 1 was started, an initiator feed composed of 2.20 grams of potassium persulfate dissolved in 107.8 grams of deionized water was begun and continued over a 240 minute period. When Feed 1 was completed, Feed 2, Table 2, was started and added to the reactor over a 50 minute period.

Table 2. Feed 2

Total time of addition for Feed 1 and 2 was 240 minutes. After the reactants were added to the reactor, the aqueous emulsion was heated for 15 minutes at 80°C. While stirring the aqueous emulsion at 300 rpm, 165 grams of deionized water was added to decrease the emulsion solids to 42%. The pH was then adjusted to 7.2 by slowly adding a solution of triethylamine that contained 1% Surfactant 1 and 0.5% deionized water. Then, a pressure-equalizing dropping funnel equipped with a rubber septum was charged with 33.41 grams of water and 8.36 grams (0.15 mole) of propylenimine. The mixture was added to the aqueous emulsion at room temperature, and the mixture was stirred for 1 hour at 60°C to effect reaction of the imine and form amine groups in the surface area of the emulsion. A second emulsion was prepared in the same manner as described above and the two emulsions were combined and designated as Preparation A, which had a total solids content of 41.55%, a pH of 8.6, and a minimum filming temperature of 45.8°C.

Examples 1-9 Modification of Preparation A aoueous emulsion The ingredients and amounts listed in Table 3 were used. The appropriate amount of Preparation A emulsion was charged to a glass reactor equipped with a mechanical stirrer, condenser, thermometer, and feeding port. Then, a mixture of allyl glycidyl ether, glycidyl methacrylate, and Surfactant 1 were added dropwise to the stirring emulsion. The deionized water was added to adjust solids to the indicated level. The emulsion was stirred at room temperature for 30 minutes and then the temperature was increased to 80°C and held there for the indicated time. The aqueous emulsion was then cooled to room temperature, filtered, and properties were determined. Gel fraction of the emulsion particles was determined by adding 2.0 grams of emulsion to 35 milUUters of acetone, swirling the mixture for 5 minutes, and then centrifuging for 30 minutes at 18,000 rpm. The Uquid was removed and a second 35 miUiliters of acetone was added to the solid material. The mixture was swirled and centrifuged as previously described. The procedure was repeated again, and then the residue sample was dried in a forced-air oven at 75° C for 2 hours. The film gel fraction was then determined in the usual manner.

l

N>

Examples 10-18 and Control I Evaluation of aαueous emulsion polymers A solvent blend composed of 62.5 parts by weight of i- butyl isobutyrate and 37.4 parts by weight of ethyoxyethoxy butanol was prepared. Ten grams of each emulsion from Examples 1-9 and Preparation A were combined with 2.3 parts of the solvent blend, stirred for 30 minutes, and aUowed to stand overnight to form the compositions of Examples 10-18 and Control I, respectively. The formulations were then drawn down in 6-mil wet films on cold-rolled steel panels and aUowed to air dry for 2 days in a constant temperature and humidity room (48% relative humidity, 66°F). Dry film thicknesses varied from 1.0 to 1.5 mils. Properties are given in Table 4.

Table 4

2.6

The higher gel fraction for all examples over that of the control indicates that the emulsions of the invention can be insolubhzed.

Esξ-ip le 19 Modification of Preparation A aαueous emulsion A glass reaction flask equipped with a stirrer, thermometer, and condenser was charged with 99.7 grams of Preparation A. Then a mixture of 0.254 gram of allyl glycidyl ether, 0.055 gram Surfactant 1, and 1.31 grams of 3,4-epoxycyclohexane methacrylate compound were added to the stirring emulsion. To adjust solids, 1.40 grams of deionized water were added. The emulsion was stirred for 30 minutes at room temperature and then heated to 80°C and held there for two hours. The resultant emulsion had a total solids content of 41.7%.

Esampte 20

Modification of Preparation A acmeous emulsion Example 19 was repeated except 2.07 grams of 3,4- epoxycyclohexane methacrylate was used. Total solids was 41.7%.

Preparation B Preparation of a core and shell aαueous emulsion A glass reactor equipped with a stirrer, thermometer, nitrogen inlet and outlet, and feeding ports was charged with 986.43 grams of deionized water, 1.07 grams of Surfactant 1, and 1.43 grams of Surfactant 2. A nitrogen purge was started, and the contents of the reactor were heated to 80° C while stirring at 400 revolutions per minute (rpm). To form the core of the aqueous emulsion particles, after temperature was reached, 50 grams of Feed 1, Table 5, were added along with a mixture containing 3.0 grams of potassium persulfate dissolved in 147 grams of deionized water and stirred for 5 minutes.

Then, with the temperature maintained at 80° C, the remainder of Feed 1 was added over a 190 minute period. Immediately after Feed 1 was started, an initiator feed composed of 2.20 grams of potassium persulfate dissolved in 107.8 grams of deionized water was begun and continued over a 240 minute period. When Feed 1 was completed, Feed 2, Table 6, was started and added to the reactor over a 50 minute period.

Table 6 Feed 2. Aqueous Emulsion Polvmer SheU Feed

Monomer

Methyl methacrylate

Styrene n-Butyl methacrylate

Methacrylic acid

Hydroxyethyl acrylate

Surfactant 1

Surfactant 2

Total time of addition for Feeds 1 and 2 was 240 minutes. After the reactants were added to the reactor, the aqueous emulsion was heated for 15 minutes at 80° C. The emulsion, which had a 42.9% total solids, was cooled and stored for future use.

Example 2i

Modification of the Preparation B aαueous emulsion A glass reactor was equipped with a condenser, stirrer, and thermometer and charged with 400 grams of Preparation B emulsion. Then a mixture containing 1.00 gram allyl glycidyl ether, 10.11 grams of l-(l-isocyanato-l-mehyl ethyl)-3-(l-methyl ethenyDbenzene, m-TMI, and 0.055 gram Surfactant 1 were added in a dropwise manner to the stirring emulsion at room temperature. Then 10.1 grams of deionized water were added to adjust solids. The emulsion was stirred for 30 minutes at room temperature and then heated to 80°C and held there for 3 hours. The latex was cooled to room temperature and stored for future use. Total solids content was 43.2%.

Example 22

Modification of Preparation A aαueous emulsion A glass reactor was equipped as in Example 19. To the reactor, 99.7 grams of Preparation A aqueous emulsion were added. Then a mixture of 0.254 gram of aUyl glycidyl ether, 0.854 gram of glycidyl acrylate, and 0.055 gram of Surfactant 1 were added dropwise to the stirring emulsion. To adjust solids, 1.41 grams for deionized water were added. The emulsion was stirred at room temperature for 30 minutes and then the temperature was increased to 80°C and held there for 2 hours. SoUds content was 40.9%. Gel fraction was determined as described in Examples 1-9 and found to be 12.2%. Examples 23-26 Evaluation of aαueous emulsion polymers The products of various examples were examined for gel fraction content in the same manner as described in Examples 10-18.

The results are given in Table 7.

Table 7

Examples Emulsion 23 24 25 26 polvmer of: . Gel Fraction. %

Example 19 21.6

Example 20 - 5.6 - -

Example 21 - - 37.8

Example 22 - - - 39.7

Although the invention has been illustrated by certain of the preceding examples, it is not to be construed as being limited thereby; but, rather, the invention encompasses the generic area as hereinbefore disclosed. Various modifications and embodiments can be made without departing from the spirit and scope thereof.

Claims

1. A polymer having one or more pendant flexible side chains connected thereto, wherein said pendant flexible side chains contain ethylenic unsaturation and are connected to said polymer by (1) an ester linkage or by (2) an ester linkage and an amine Hnkage or by (3) an ester linkage and a urea linkage, said ester linkage in (1) formed by the reaction of an ethylenically unsaturated epoxide with a carboxylic acid group on said polymer, said ester linkage in (2) and (3) formed by the reaction of an imine with a carboxylic acid group on said polymer to form an amine group connected to the polymer, said amine linkage in (2) formed by the reaction of an ethylenically unsaturated epoxide with said amine group, and said urea linkage in (3) formed by the reaction of an ethylenically unsaturated isocyanate with said amine group.

2. The polymer of claim 1 wherein the ethylenically unsaturated epoxide is one or more epoxide (meth)acrylates selected from glycidyl acrylate, glycidyl methacrylate, an allyl glycidyl (meth)acrylate, 3,4-epoxycyclohexane (meth)acrylate or mixtures thereof, and the imine is one or more alkylene imines selected from 2- isocyanatoethyl (meth)acrylate, l-(l-isocyanato-l-methyl ethyl)-4-(l- methyl ethenyl) benzene or mixtures thereof.

3. A process for preparing a polymer having one or more pendant flexible side chains connected thereto comprising:

(b) optionally post reacting the precursor polymer with one or more ethylenically unsaturated epoxides; (c) post reacting the precursor polymer of step (a) with one or more imines;

4. The process of claim 3 wherein step (a) is carried out at a temperature of about 40°C to about 100°C and a pressure of about atmospheric to about 100 psig, and steps (b), (c) and (d) are carried out at a temperature of about 0°C to about 100°C and a pressure of about atmospheric to 100 psig.

5. The process of claim 3 in which at least 5% of the polymer precursor acidity is consumed in step (b) or step (c), and in which said ethylenically unsaturated epoxide or said imine is used in stoichiometric deficiency with respect to the carboxyl group functionality in said polymer precursor, the epoxide or imine functionality being consumed in the process with the excess carboxyl group functionality.

6. An ambient curable coating composition (and cured film prepared therefrom) comprising the polymer of claim 1, optionally a plasticizer, and optionally one or more drier salts.

7. A thermaUy curable coating composition (and cured film prepared therefrom) comprising the polymer of claim 1, an oxygen-producing compound, and optionally a plasticizer and/or one or more drier salts.

8. A radiation curable coating composition (and cured film prepared therefrom) comprising the polymer of claim 1, a photoinitiator, and one or more radiation-polymerizable unsaturated compounds.

9. A latex composition or an air drying and air curable latex coating composition comprising water and the polymer of claim 1.

10. A water-borne or solvent-borne composition comprising the polymer of claim 1.