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Nitrile Acrylate Coating Composition Containing Pendant Functionality

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Nitrile Acrylate Coating Composition Containing Pendant Functionality Europaisches Patentamt ® European Patent Office © Publication number: 0 257 812 Office europeen des brevets A2 © EUROPEAN PATENT APPLICATION © Application number: 87306655.9 C09D 3/00 int. CIA , C08F 291/00 , C08F 265/08 C08F 265/04 © Date of , , filing: 28.07.87 C08F 2/46 © Priority: 05.08.86 US 893414 © Applicant: THE STANDARD OIL COMPANY 200 Public Square, 36-F-3454 © Date of publication of application: Cleveland Ohio 4411 4-2375{US) 02.03.88 Bulletin 88/09 © inventor: Bartoszek-Loza, Rosemary © Designated Contracting States: 6570 Arbordale Avenue DE FR GB Solon Ohio 44139(US) Inventor: Butler, Richard J. 23951 Lakeshore Blvd., No. 1207 Euclid Ohio 44123(US) © Representative: Smith, Sydney et al Elkington and Fife High Holborn House 52/54 High Holborn London WC1V 6SH(GB) © Nitriie acrylate coating composition containing pendant functionality and a radiation curable process. © A coating composition comprising a nitriie acrylate polymer with pendant functionality useful as protective coatings. The composition comprises a nitriie monomer, acrylate monomer and multifunctional monomer; a reactive diluent; and a photoinitiator. The composition is 100% solvent free. This invention further includes a process for producing 100 percent solids coatings that are corrosion resistant, adhesion cohesive and hard. C"4 < CM 00 r> ID CM Xerox Copy Centre 0 257 812 N1TRILE ACRYLATE COATING COMPOSITION CONTAINING PENDANT FUNCTIONALITY AND A RADI- ATION CURABLE PROCESS The present invention is directed generally to radiation curable coating compositions containing nitrile acrylate polymers with pendant functionality for use as protective coatings on various substrates such as metals, piastics, woods and the like. In another aspect, the invention relates to a novel nitriie acrylate coating composition containing pendant functionality. In another aspect, the invention relates to a novel 100 5 percent solids, room temperature radiation curable, in particular photocurable coating composition. In another aspect, the invention relates to a novel coating composition, and novel radiation curable process to produce the coating which coatings have excellent hardness, adhesion, barrier properties and corrosion resistance. The desirability of forming photocurable coating compositions which can be developed without the need w of conventional organic solvents has long been recognized. Organic solvents are costly, hazardous and need to be removed from the final coating, which requires considerable thermal energy. In accordance with this invention, it has now been discovered that nitrile acrylate multifunctional radiation cured coatings can be produced in a solventless system. Nitriie polymer coatings are known in the art for their barrier properties to oxygen and water. However, 75 in coatings there is limited solubility of the nitrile polymers which restricts the number of solvents that can be employed as reactive diluents. Enhanced solubility is desirable for increasing the reactivity of the nitrile polymers with reactive diluents and for expanding the use of the coating. The incorporation of an acrylate polymer with the nitrile polymer increases the solubility of the resultant nitrile acrylate polymer. Pendant functionality through the use of a multifunctional monomer was incorporated into the nitrile 20 acrylate polymer to enhance the homogenecity, cohesion and adhesion of the coating composition. In accordance with this invention, it was discovered that the synthesis of a nitrile acrylate polymer with pendant functionality would add to the polymer composition at least two reactive sites from the multifunc- tional monomer which would provide a site for incorporation into the polymer backbone and an additional site for subsequent crossiinkir.g and grafting to the polymer and/or reactive diluent upon s cure to mir.tr-'izs 25 channeling effects in the coating while retaining the solubility and barrier properties of the nitrile acrylate polymer system. It is an object of this invention to produce a novel composition containing a nitrile acrylate polymer with pendant functionality for use as a coating or adhesive material. It is another object of this invention to produce a coating composition in a 100 percent solids, solvent free system to avoid the use of solvents. It 30 is another object of this invention to produce the novel coating by a novel radiation curable process at ambient temperature. It is another object of this invention to produce radiation cured, in particular photocured, coatings which are hard, adhesive, cohesive and corrosion resistant. These and other objects, together with the advantages over known methods shall become apparent from the specification which follows and are accomplished by the invention as herein described and 35 claimed. SUMMARY OF THE INVENTION 40 This invention relates to a composition comprising a polymer comprising a nitrile monomer, an acrylate monomer and a multifunctional monomer; a reactive diluent and a photoinitiator. The novel composition of the instant invention are radiation cured to a tack free coating or adhesive material. The invention further includes a process to produce the novel composition comprising: 1. preparing a polymer comprising a nitrile monomer, an acrylate monomer and a multifunctional 45 monomer; 2. forming a mixture of said polymer, a reactive diluent and a photoinitiator; 3. applying said mixture of the composition to a substrate; and 4. curing the composition by radiation to form a tack free coating or adhesive material. The coatings produced by the process of the instant invention have excellent hardness, adhesion and 50 corrosion resistance. The coating compositions of the instant invention are excellent coating and adhesive materials. 0 257 812 The radiation curable nitrile acrylate coating compositions containing pendant functionality of the instant invention can be used for industrial protection of various substrates, in particular metals where properties such as adhesion, hardness and corrosion resistance are important. Major uses for the coatings would be in the automotive industry, oil industry, pulp and paper industry and others. Further, the novel composition 5 may be employed as an adhesive material or an encapsulant. DETAILED DESCRIPTION OF THE INVENTION io The radiation curable coating composition of the instant invention are the reaction products of a polymer comprising a nitrile monomer, an acrylate monomer and a multifunctional monomer; a reactive diluent and a photoinitiator. The first component of the coating composition of the instant invention is a polymer synthesized from a nitrile monomer, an acrylate monomer and a multifunctional monomer. The polymer is characterised as a 75 nitrile acrylate polymer containing pendant functionality. The pendant functionality is defined as an incorporation of a multifunctional monomer that has at least two reactive sites, one reactive site for crosslinking into the polymer backbone upon polymer formation and another reactive site for subsequent crosslinking and grafting into the polymer backbone and/or reactive diluent upon cure of coating. The coating composition generally contains from about 5 weight percent to about 60 weight percent, 20 preferably from about 15 weight percent to about 50 weight percent and most preferably from about 25 weight percent to about 40 weight percent of the polymer. The polymer can be employed either alone or in combination. The polymer can be prepared by any method known in the art. Preferably, the polymer is prepared by emulsion or solution polymerization of the nitrile monomer, acrylate monomer and multifunctional monomer 25 copolymerizable therewith. Preferred polymers useful in the coating composition of the instant invention are prepared by the polymerization of: 100 parts by weight of (A) from about 60 percent to about 80 percent by weight of at least one nitrile monomer having the structure: 30 (A) CH2 = C-(R)-CN (A) CH2 = C-(R)-CN wherein R is hydrogen, a lower alkyl group having from 1 to 6 carbon atoms or a halogen; and 35 from about 3 percent to about 30 percent of at least one acrylate monomer having the structure: (B) CH2 = C-(Ri)-COOR2 wherein Ri is hydrogen, an alkyl group having from 1 to 6 carbon atoms or a halogen, and R2 is an alkyl 40 group having 1 to 30 carbon atoms; and from about 3 percent to about 30 percent of at least one multifunctional monomer having the structure: (C) CH2=CH-X-S 45 wherein X is an acrylate, polyester, alkyl, epoxy, isocyanate, formaldehyde, phenolformaldehyde or nitrile backbone group and S is olefinic unsaturation group, hydroxy group, epoxy group, isocyanate group or carboxyiic acid and/or ester. so Chain transfer agents can optionally be used in the polymerization of the nitrile acrylate polymer with pendant functionality. Chain transfer agents can be used to control the molecular weight of the nitrile acrylate polymer. Chain transfer agents and the use thereof are generally well known in the art. Chain transfer agents can be employed either alone or in combination. Examples of typical chain transfer agents include but are not limited to methyl mercaptan, ethyl mercaptan, n-propyl mercaptan, isopropyl mercaptan, 55 n-butyl mercaptan. t-butyl mercaptan, n-hexyl mercaptan, cyclohexyi mercaptan, n-octyl mercaptan, t-octyl mercaptan, t-nonyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, tridecyl mercaptan and the like. 0 257 812 In the practice of this invention the nitriie monomer employed in the polymerization of the polymer can be employed
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