Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/42—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
  • C08G59/4215—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof cycloaliphatic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins

Definitions

• thermosetting coating composition of this invention preferably contains greater than about 60% by
• composition is characterized in that it comprises a mixture of:
• composition reacts in situ during curing at elevated temperatures to form the coating.
• composition of this invention being of essentially single step formulation, offers a distinct commercial advantage over those compositions whose formulation includes a series of reaction steps prior to curing, since such reaction steps generally require heat, agitation and monitoring for extended periods of time.
• carboxyl functionality is generated which, until it is later consumed by further reaction, acts as a catalyst for the crosslinking reaction.
• the coating compositions of this invention provide a system which is particularly suitable for those applications requiring a coating having high gloss, hardness, adhesion, high solvent and water resistance and
• One material in the high solids coating composition of this invention is a hydroxy functional acrylic copolymer, i.e., a copolymer bearing pendant hydroxyl groups, which may be prepared by conventional free radical induced polymerization of suitable alpha-beta unsaturated monomers.
• copolymer refers to a copolymer of two or more different monomers at least one of which contains pendant hydroxyl groups.
• the copolymers used in the coating composition of this invention have a number average molecular weight (M n ) of between about 1000-5000, preferably between about 1500-3000.
• the monomers used to prepare the copolymer include between about 10 and about 40 weight percent of one or more monoethylenically unsaturated monomers bearing hydroxyl functionality.
• the preferred hydroxy functional monomers for use in the copolymer of the invention are C 5 - C7 hydroxy alkyl acrylates and/or Cg - Cs hydroxy alkyl methacrylates, i.e., esters of C2 - C4 dihydric alcohols and acrylic or methacrylic acids.
• the remainder of the monomers forming the copolymer i.e., between about 90 and about 60 weight percent of the monomers of the copolymer, are other monoethylenically unsaturated monomers.
• These other monoethylenically usaturated monomers are preferably alpha-beta olefinically unsaturated monomers, i.e., monomers bearing olefinic unsaturation between the two carbon atoms in the alpha and beta positions with respect to the terminus of an aliphatic carbon-to-carbon chain.
• alpha-beta olefinically unsaturated monomers which may be employed are other acrylates (meaning esters of either acrylic or methacrylic acids not containing hydroxyl functionality), as well as mixtures of other acrylates and monovinyl hydrocarbons.
• acrylates meaning esters of either acrylic or methacrylic acids not containing hydroxyl functionality
• mixtures of other acrylates and monovinyl hydrocarbons Preferably, in excess of 50 weight percent of the total of the copolymer monomers are acrylates (this total including hydroxy functional acrylates and other acrylates).
• acrylates are preferably selected from esters of C j _ - C 2 monohydric alcohols and acrylic or methacrylic acids, i.e., methyl methacrylate, ethylacrylate, butylacrylate, ( iso)-butylmethacrylate, hexylacrylate, 2-ethylhexyl acrylate, lauryl ethacrylate, etc.
• Monovinyl hydrocarbons when they are employed, ' should preferably constitute less than 50 weight percent of the copolymer.
• the monovinyl hydrocarbons suitable for use in forming the copolymers are those containing 8 to 12 carbon atoms and including styrene, alpha methylstyrene, vinyl toluene, t-butylstyrene and chlorostyrene.
• Other such monovinyl hydrocarbon monomers as vinyl chloride, acrylonitrile, methacrylonitrile, and vinyl acetate may be included in the copolymer as modifying monomers. However, when employed, these modifying monomers should constitute only between about 0 and about 30 weight percent of the monomers in the copolymer.
• Small amounts of ethylencally unsaturated carboxylic acids can also be used in preparing the copolymer, such as acrylic acid, methacrylic acid, crontonic acid, itaconic acid, aleic acid and the like.
• the hydroxy functional monomers and the other monoethylenically unsaturated monomers are mixed and reacted by conventional free radical initiated polymerization in such proportions as to obtain the copolymer desired.
• free radical initiators are known to the art and are suitable for the purpose.
• the suitable solvents are toluene, methyl amyl ketone, xylene, dioxane, butanone, etc. If the hydroxy- functional copolymer is prepared in solution, the solid copolymer can be precipitated by pouring the solution at .a slow rate into a nonsolvent for the copolymer such as hexane, octane, or water under suitable agitation conditions.
• a nonsolvent for the copolymer such as hexane, octane, or water under suitable agitation conditions.
• the alkyl group preferably comprises up to about 7 carbons, more preferably up to 4 carbons.
• the alkyl hexahydrophthalic anhydride comprises methyl hexahydrophthalic anhydride.
• the remainder of the anhydrides i.e., 0 to about 50 weight percent, more preferably 0 to about 20 weight percent, and most preferably 0 to about 10 percent by weight, are selected from a variety of anhydrides, which include but are not limited to, hexahydrophthalic, 2-dodecene-l-ylsuccinic, tetrahydrophthalic, methyl tetrahydrophthalic and camphoric anhydrides, and mixtures of suitable anhydrides.
• the epoxy suitable for use in this invention is a low molecular weight epoxy which can : be a liquid or a solid and can be either a single epoxy or a mixture of suitable epoxies.
• suitable epoxies include, but are not limited to, C4 _ Cig monoepoxies such as alkylene oxides, cyclic oxides, glycidyl esters and glycidyl ethers. Amoung numerous examples of such monoepoxides are 1,2 epoxy pentane, 1,2-epoxy decane, styrene oxide, cyclohexene oxide, n-butyl glycidyl ether, glycidyl acetate and glycidol.
• Suitable diepoxides include those which are the condensation products of bisphenol-A with epichlorohydrin, examples of which are commercially available as Epon 828, 1001, 1004, 1007 and 1009 (marketed by Shell Chemical Company, Houston, Texas), Araldite 6010 and 8001 (marketed by Ciba-Geigy Corp., Ardsley, New York); ester type diepoxides such as diglycidyl phthalate, diglycidyl adipate and diglycidyl glutarate; cycloaliphatic diepoxides such as dicycopentaxediene and vinyl _ cyclohexane dioxide; and aliphatic ether type diepoxides such as ethylene glycol diglycidyl ether, 1,2-propylene glycol, diglycidyl ether and 1,4-butanediol diglycidyl ether such as Araldite RD-2 (marketed by Ciba-Geigy).
• Catalysts are generally included in the composition to accelerate the epoxide/carboxyl reaction.
• Suitable catalyst for this epoxide/carboxyl reaction are well known in the art.
• Preferred catalysts useful for this reaction are the tetralkyl ammonium salts such as tetra methyl ammonium chloride, tetraethyl ammonium bromide and trimethyl benzyl ammonium chloride as well as metal salts of a carboxylic acid, such as potassium octoate or chromium III octoate.
• catalysts include: metal halides such as chromium trichloride, ferric trichloride, and aluminum trichloride; mercaptans and thioethers such as octyl mercaptan, dimercapto propanol and dimercapto-diethyl ether; * tertiary amines such as triethyl amine, pyridine, dimethylandine, quinoline, ⁇ -picoline, ethylpyridine, and the like. Still other catalysts known to catalyze the carboxyl/epoxide reaction will be apparent to those skilled in this art.
• amine-aldehyde crosslinking agent Another essential component of the paint compositions of this invention is an amine-aldehyde crosslinking agent.
• Amine-aldehyde crosslinking agents suitable for crosslinking hydroxy functional bearing materials are well known in the art. Typically, these crosslinking materials are products of reactions of melamine, or urea with formaldehyde and various alcohols containing up to and including 4 carbon atoms.
• the amine-aldehyde crosslinking agents useful in this invention are amine-aldehyde resins such as condensation products of formaldehyde with melamine, substituted melamine, urea, benzoquanamine or substituted benzoquanamine.
• Preferred members of this class are methylated melamine-formalade yde resins such as hexamethoxylmelamine.
• These liquid crosslinking agents have substantially 100 percent nonvolatile content as measured by the foil method at 45°C for 45 minutes.
• Other suitable amine-aldehyde crosslinking agents would be apparent to one skilled in the art.
• crosslinking agents are t e amino crosslinking agents sold by American Cyanamid, Wayne, N.J. under the trademark "Cymel” .
• Cymel 301, Cymel 303, Cymel 325 and Cymel 1156 which are alkylated melamine-formaldehyde resins, are useful in the compositions of this invention.
• the crosslinking reactions are known to be catalytically accelerated by acids. Therefore, the unconsumed carboxyl group acts as a catalyst for the crosslinking reaction.
• catalysts may be added to the composition which accelerate the crosslinking reaction.
• One such catalyst for example, is p-toluene sulfonic acid and the amine salts thereof.
• the amino crosslinking agent should be included in the composition in an amount sufficient to provide at least about 0.60 preferably between about 0.75 and about 2.75 of nitrogen crosslinking functional groups for each hydroxyl group included in the composition either as an initially present and unreacted hydroxyl group on the copolymer or as a regenerated hydroxyl group i.e., by means of in situ reactions with anhydride and epoxy.
• the hydroxyl groups present in the composition and available for crosslinking can therefore be essentially taken to be equal to the hydroxyl groups initially present on the copolymer (A).
• coating compositions of the invention include materials such as catalysts, antioxidants, U.V. absorbers, solvents, surface modifiers and wetting agents, as well as pigments.
• the nonvolatile solids content of the coating composition is preferably at least 60% and more preferably 70% or more, thus limiting the amount of solvent included in the composition.
• the composition is particularly suitable for use as a high solids composition, the composition is also suitable for use as low solids compositions. Determination of optimal solids content for a given application would be within the skill of one in the art.
• Surface modifiers or wetting agents are comomon additives for liquid paint compositions. The exact mode of operation of these surface modifiers is not known, but it is thought that their presence contributes to better adhesion of the coating composition to the surface being coated and helps formation of thin coatings, particularly on metal surfaces.
• These surface modifiers are exemplified by acrylic polymers containing 0.1 - 10 percent by weight of copolymerized monoethylenically unsaturated carboxylic acids such as methacrylic acid, acrylic acid or itaconic acid, cellulose acetate butyrate, silicone oils or mixtures thereof.
• the choice of surface modifiers or wetting agent is dependent upon the type of surface to be coated and selection of the same is clearly within the skill of the artisan.
• the coating composition of the invention also may include pigments.
• the amount of pigment in the coating composition may vary, but preferably is between about 3 and about 45 weight percent based on the total weight of the paint composition. If the pigment is metallic flake, the amount generally ranges from about 1 to about 20 weight percent.
• NAD's such as described by Porter (S. Porter, Jr. and B.N. McBane, U.S. Patent 4,025,474, May 24, 1977) are compatible with these coating compositions. These particle dispersions may be included in an amount up to 15% by weight of the total composition.
• Other types of NAD's such as described by D.L. Maker and S.C. Peng (U.S. Patent 3,814,721, June 4, 1974) or by S.K. Horvath (U.S. application Serial No. 292,853, filed August 14, 1981) also may be included in the paint composition.
• the coating composition can be applied by conventional methods known to those skilled in the art. These methods include roller coating, spray coating, dipping or brushing and, of course, the particular application technique chosen will depend on the particular substrate to be coated and the environment in which the coating operation is to take place.
• a particularly preferred technique for applying the high solids coating compositions is spray coating through the nozzle of a spray gun.
• High solids paints have in the past caused some difficulty in spray coating techniques because of the high viscosity of the materials and resultant problems in clogging of spray guns.
• the compositions of this invention demonstrate relatively low viscosity, considering the high solids content, they can be applied by spray coating techniques.
• a hydroxy acrylic copolymer is prepared from the following monomers:
• Methyl methacrylate 160 40 Styrene 20 5
• a hydroxy acrylic copolymer is prepared from the following monomers:
• An acrylic copolymer is prepared from the following monomers:
• the preparation is carried out in the same way as outlined in Example 1 by using cellusolve acetate as the solvent and tert-butyl peroctoate (5% of monomers) as initiator to obtain a 70% solution of the polymer.
• Example 7 Fifty-two (52) parts of the above mill base are mixed with 20 parts of polymer from Example 4, 13.5 parts of ⁇ pon 828 (Shell Chemical Co.), 19 parts of Cymel 325, 0.15 parts of Cordova Accelerator AMCTM-2 and 16 parts of butyl acetate. Twelve (12) parts of methylhexa ⁇ hydrophthalic anhydride are added to the above mixture and the resulting formulation is applied by spraying to primed steel panels which are baked at 130°C for 18 minutes to obtain hard, glossly yellow coatings with excellent solvent resistance.
• Example 7 Twelve (12) parts of methylhexa ⁇ hydrophthalic anhydride are added to the above mixture and the resulting formulation is applied by spraying to primed steel panels which are baked at 130°C for 18 minutes to obtain hard, glossly yellow coatings with excellent solvent resistance.
• phthalo blue pigment Five (5) parts of phthalo blue pigment are mixed with 45 parts of the polymer from Example 1 and the mill base is ground as described in Example 5.
• Example 9 Twenty-four (24) parts of the above mill base are mixed with 32 parts of the polymer from Example 1, 27 parts of Cymel 325, 14 parts of Epon 828 (Shell Chemical Co.), 8 parts flow control additive (prepared according to U.S. Patent 4,025,474), 0.1 part Cordova Accelerator AMCTM-2, 5 parts of aluminum flakes and 18 parts of butyl acetate. Twelve (12) parts of methylhexahydrophthalic anhydride are added to the above mixture and the resulting formulation is applied by spraying in four coats. The panels are baked at 130°C for , 18 minutes to obtain blud metallic coatings with excellent physical properties.
• Example 9 Twenty-four (24) parts of the above mill base are mixed with 32 parts of the polymer from Example 1, 27 parts of Cymel 325, 14 parts of Epon 828 (Shell Chemical Co.), 8 parts flow control additive (prepared according to U.S. Patent 4,025,474), 0.1 part Cordova Accelerator AMCTM-2, 5 parts of aluminum flakes and 18 parts of but
• a hydroxy acrylic copolymer is prepared from the following monomers:
• this invention has industrial applicability, particularly to the automotive industry, and provide a coating with excellent exterior weatherability and distinct commercial advantages.

Applications Claiming Priority (1)

Publications (2)

Family

ID=22168139

Family Applications (1)

Country Status (2)

Families Citing this family (16)

Citations (2)

Family Cites Families (5)

• 1982
  • 1982-08-09 WO PCT/US1982/001091 patent/WO1984000771A1/en not_active Application Discontinuation
  • 1982-08-09 EP EP19820903089 patent/EP0115484A4/de not_active Withdrawn

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events