BLENDS OF EPOXY RESINS, PHOSPHATE ESTERS OF EPOXY RESINS

Abstract: Properties of can and coil coatings are improved by employing as the curable composition a blend or mixture of (A) at least one compound containing an average of more than one vicinal epoxide group per molecule; (B) at least one compound containing an average of two phenolic hydroxyl groups per molecule; and (C) at least one epoxy phosphate ester; and (D) a curing amount of at least one curing agent.

Description: BLENDS OF EPOXY RESINS, PHOSPHATE ESTERS OF EPOXY RESINS The present invention pertains to a blend or mixture of an epoxy resin and a phosphate ester of an epoxy resin; curable compositions containing such blend; coating compositions containing such curable compositions; articles prepared from the curable compositions; and articles coated with such coating compositions. The can and coil coating industry has an almost universal need for coatings with better flexibility and formability characteristics. Three-piece can technology is being replaced by two-piece can technology. The two-piece technologies, for example, draw-redraw (DRD), are very demanding on the applied organic coatings. DRD is a process for making two piece cans in which a circular blank is drawn through a die to form a circular cup and then redrawn through a second or third die to produce a can of desired dimensions. Since tlie DRD process uses pre-coated metal coil, there is an industry demand for more formable can coatings to withstand the stress associated with the can formation process. In today's market, precoated sheets of metal are subjected to many severe operations in order to form the metal into an assortment of shapes. These operations include stamping, drawing, redrawing, flanging, beading, riveting, and folding. Formability tests typically used in the can and coil industry can be classified as slow or rapid deformation techniques. Some examples of slow deformation tests are T-bend, Erichsen indention, Erichse cupping test and the beading test. Examples of fast deformation techniques include wedge bend, Gardner impact test and actual can stamping. It would be desirable to have available coating systems which provide an improvement in one or more of the properties: flexibility, acid resistance, oil and fat resistance, and the like. The present invention pertains to a blend or mixture comprising ( A ) at least one compound containing an average of more than one vicinal epoxide group per molecule; - 1 (B ) at least one compound containing an average of two phenolic hydroxyl groups per molecule; and (C) at least one epoxy phosphate ester; wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 20:1, preferably from 0.05:1 to .8:1, more preferably from 0.05:1 to 0.6:1; and component (C) is present in an amount of from 1 to 80, preferably from 5 to 50, more preferably from 10 to 30 percent by weight based on the combined weight of components (A and B). When the ratio of phenolic hydroxyl groups to epoxy groups is 1:1, the product produced is randomly terminated in epoxy groups or phenolic hydroxyl groups. Another aspect of the present invention pertains to a curable composition comprising a blend or mixture of (A) at least one compound containing an average of more than one vicinal epoxide group per molecule; (B) at least one compound containing an average of two phenolic hydroxyl groups per molecule; and (C) at least one epoxy phosphate ester; and (D) a curing amount of at least one curing agent; wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 20:1, preferably from 0.05:1 to 0.8:l,more preferably from 0.05:1 to 0.6:1; and component (C) is present in an amount of from 1 to 80, preferably from 5 to 50, more preferably from 10 to 30 percent by weight based on the combined weight of components (A and B); and component (D) is present in an amount of from 0.5 to 60, preferably from 2 to 30, more preferably from 2 to 20 percent by weight based upon the combined weight of components (A), (B), (C) and (D). Another aspect of the present invention pertains to a coating composition comprising (I) a curable composition comprising a blend or mixture of ( A ) at least one compound containing an average of more than one vicinal epoxide group per molecule; ( B ) at least one compound containing an average of abut two phenolic hydroxyl groups per molecule; and (C) at least one epoxy phosphate ester; and (D) a curing --mount of at least one curing agent; and (II) an inert carrier or solvent; wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 20:1, preferably from 0.05:1 to 0.8:l,more preferably from 0.05:1 to 0.6:1; and component (C) is present in an amount of from 5 to 80, preferably from 10 to 50, more preferably from 15 to 30 percent by weight based on the combined weight of components (A and B); component (D) is present in an amount of from 0.5 to 60, preferably from 2 to 30, more preferably from 2 to 20 percent by weight based upon the combined weight of components (A), (B), (C) and (D); and component II is present in an amount of from 10 to 90, preferably from 20 to 80, more preferably from 30 to 75, percent by weight based upon the combined amount of components (I) and (H). The following formulas are used throughout the specification. Formula I Formula II ; Formula V Suitable compounds which can be employed as the vicinal epoxide-containing compound (epoxy resin), component (A), in the present invention include, for example, glycidyl ethers of dihydric phenols, advanced epoxy resins prepared by reacting a diglycidyl ether of a dihydric phenol with a dihydric phenol which may be the same or different from the dihydric phenol in the diglycidyl ether of a dihydric phenol, glycidyl ethers of alkylene oxide adducts of dihydric phenols, advanced epoxy resins prepared by reacting glycidyl ethers of alkylene oxide adducts of dihydric phenols with a dihydric phenol or an alkylene oxide adduct of a dihydric phenol wherein the dihydric phenols in each instance can be the same or different. By the term dihydric phenol it is meant that the compound has two phenolic hydroxyl groups per molecule. Particularly suitable epoxy resins which can be employed herein as component (A) include those represented by the formulas I, π, in, IV and V wherein each A is independently a divalent hydrocarbyl group having suitably from 1 to 12, more suitably from 1 to 6, most suitably from 1 to 4 carbon atoms; each R is independently hydrogen or an alkyl group having from 1 to 3 carbon atoms; R' is hydrogen, an alkyl group having suitably from 1 to 6, more suitably from 1 to 4 a carbon atoms or a hydrocarbyl, or a hydrocarbyloxy group having from 1 to 4 carbon atoms; each R is independently a divalent hydrocarbon group having from 1 to 6 carbon atoms; each X is independently hydrogen, a hydrocarbyl or hydrocarbyloxy group having suitably from 1 to 12, more suitably from 1 to 6, most suitably from 1 to 4 carbon atoms or a halogen atom, preferably chlorine or bromine; each Z is a glycidyl group or a methyl, ethyl or propyl substituted glycidyl group; Z' is a divalent aromatic group having suitably from 6 to 20, more suitably from 6 to 15 carbon atoms or Z" is a group represented by the following Formulas A, B, C or D: Formula A Formula B Formula C m has a value suitably from 0.01 to 8, more suitably from 1 to 6, most suitably from 2 to 4; n has a value of zero or 1; n' has an average value suitably from 1 to 90, more suitably from 1 to 60, most suitably from 1 to 50. The term hydrocarbyl as employed herein means any aliphatic, cycloaliphatic, aromatic, aryl substituted aliphatic or cycloaliphatic, or aliphatic or cycloaliphatic substituted aromatic groups. Likewise, the term hydrocarbyloxy means a hydrocarbyl group having an oxygen linkage between it and the element to which it is attached. The term divalent hydrocarbyl group refers to the aforementioned hydrocarbyl groups minus an additional hydrogen atom. The epoxy resins employed as component (A) usually have an epoxide equivalent weight (EEW) of from 400 toll,000, preferably from 400 to 4,000, more preferably from 400 to 3,000. The epoxy resins can be prepared by reacting an excess of an epihalohydrin such as epichlorohydrin, epibromohydrin or epiiodohydrin or a methyl, ethyl or propyl substituted epihalohydrin with a dihydric phenol or oxyalkylated derivative thereof of dicarboxylic add or anhydride thereof in the presence of a catalyst at a temperature of from 20°C to 150°C, preferably from 25°C to 100°C, more preferably from 30°C to 70°C for a time suffident to complete the reaction to form a halohydrin intermediate. Usually, the time required to form the halohydrin intermediate is from 0.5 to 125, preferably from 1 to 100, more preferably from 1 to 50, hours. The halohydrin intermediate is then dehydrohalogenated to the glycidyl compound by reaction with a basic-acting compound at a temperature of from 20°C to 30°C, preferably from 22°C to 28°C, more preferably from 24°C to 26°C for a time suffident to complete the reaction to form the glyddyl compound. Usually, the time required to complete the dehydrohalogenation reaction is from 0.25 to 10, preferably from 0.25 to 7, more preferably from 0.25 to 6, hours. Suitable basic-acting compounds include, the alkali metal and alkaline earth metal hydroxides, carbonates and bicarbonates. Particularly suitable basic-acting dehydrohalogenation agents indude, for example, sodium and potassium hydroxide. Particularly suitable dihydric phenols indude, for example, bisphenol A (4,4'- isopropylidenediphenol), bisphenol F (2,2'-methylenediphenol), bisphenol K (4,4'- dihydroxybenzophenone), bisphenol S (4,4'-sulfonyldiphenol), or any combination thereof. Particularly suitable oxyalkylated dihydric phenols indude, for example,the reaction product of bisphenol A, bisphenol F, bisphenol K, bisphenol S, or any combination thereof with an alkylene oxide such as, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, . 2,3-butylene oxide, or any combination thereof. The alkylene oxide is usually reacted in amounts of from 1 to 6, preferably from 1 to 3, more preferably from 1 to 2 moles per aromatic hydroxyl group present in the dihydric phenol. The reaction is usually conducted at a temperature of from 20°C to 60,°C preferably from 20°C to 50°C, more preferably from 25°C to 40°C in the presence of a suitable catalyst such as, for example, potassium hydroxide, sodium hydroxide, or any combination thereof. Particularly suitable dibasic adds or anhydrides thereof include, for example, adipic add, sucdnic add, azelaic add, sebacic acid, 1,4-tetradecanedicarboxyIic add, or any combination thereof. The advanced (higher molecular weight) epoxy resins can be prepared by reacting a diglyddyl ether of a dihydric phenol or diglyddyl ester of a dibasic acid or anhydride thereof with a dihydric phenol or an oxyalkylated dihydric phenol in the presence of a suitable catalyst and optionally in the presence of a suitable solvent. Particularly suitable dihydric phenols include those represented by the formulas I and II wherein A, R, X, n and n' are as previously defined; and Z is hydrogen. The advancement reaction is usually conducted at temperatures of from 100°C to 300°C, preferably from 120°C to 250°C, more preferably from 150°C to 200°C for a time sufficient to complete the advancement reaction. The time depends upon the particular reactants and catalysts but is usually from 0.5 to 8, preferably from 1 to 6, more preferably from 1 to 4, hours. Suitable catalysts which can be employed to prepare the advanced epoxy resins include, for example, ethyltriphenylphosphonium acetate-acetic add complex; ethyltriphenylphosphonium chloride, bromide, iodide, or phosphate, tetrabiitylphosphonium acetate-acetic acid complex, and tetrabutylphosphonium chloride, bromide, iodide, or phosphate, or any combination thereof. The catalysts are typically used at levels of from 0.0001 to 0.05, preferably from 0.001 to 0.2, more preferably from 0.001 to 0.01 mole of catalyst per epoxide group. Suitable solvents which can be employed in the preparation of the advanced epoxy resins include, for example, ketones, aromatic and aliphatic hydrocarbons, glycol ethers, or any combination thereof. Particularly suitable solvents include, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, propylene glycol methyl ether, ethylene glycol butyl ether, or any combination thereof. The solvents, when employed, are used in amounts of from 5 to 60, preferably from 5 to 50, more preferably from 10 to 50, percent by weight based upon the combined weight of the reactants. Suitable compounds having an average of 2 phenolic hydroxyl group per molecule which can be employed herein as component (B) indude, for example, dihydric phenols represented by formulas I and II wherein A, R, X, n and n' are as defined above and Z is hydrogen. Particularly suitable compounds having an average of 2 phenolic hydroxyl group per molecule are those compounds prepared by reacting an epoxy resin with an excess of a dihydric a phenol. Suitable epoxy resins include those represented by formulas I, II or III wherein A, R, R', R , X, 71, m, n, n' and π" are a previously defined and Z is hydrogen. Suitable dihydric phenols or oxyalkylated dihydric phenols include, for example, those described above as being suitable dihydric phenols for use in the preparation of advanced (high molecular weight) epoxy resins. The epoxy phosphate esters which can be employed herdn as component (C) can be prepared by reaction an epoxy-containing compound with a phosphoric add source at a temperature of from 50°C to 300°C, preferably from 50°C to 200°C, more preferably from 50°C to 150°C for a time to complete the reaction, usually from 0.1 to 6, preferably from 0.5 to 3, more preferably from 1 to 2 hours. The higher reaction temperatures require less reaction time than the lower reaction times. The epoxy-containing compound and the phosphoric acid source are employed in quantities which provide a ratio of moles of phosphoric acid per epoxide group of from 0.2:1 to 1:1, preferably from 0.5:1 to 1:1, more preferably from 0.8:1 to 1:1. The epoxy phosphate esters can be totally or partially hydrolyzed by reaction with water. The reaction can be conducted at a temperature of from 50°C to 300°C, preferably from 100°C to 200°C, more preferably from 100°C to 150°C for a time suffident to complete the reaction, usually from 0.1 to 8, preferably from 0.1 to 4, more preferably from 0.1 to 2 hours. The higher reaction temperatures require less reaction time "than the lower reaction times. The water can be employed in an amount corresponding suitably to a ratio of moles of water per mole of epoxy resin employed of from 0.5:1 to 100:1, more suitably from 0.5:1 to 50:1, most preferably from 0.5:1 to 2:1. Suitable phosphoric add sources indude, for example, phosphoric acid, super phosphoric add, other condensed forms of phosphoric add, aqueous solutions containing at least 18% H3PO4, and phosphoric add esters, combinations thereof. Suitable phosphoric add esters indude, for example, dibutyl phosphate, dibutoxy phosphate, or any combination thereof. . Suitable epoxy resins which can be employed to prepare the phosphate esters thereof indude any epoxy resin having an average of more than one vicinal epoxy group per molecule. These include, aliphatic, cycloaliphatic, or aromatic based epoxy resins. Suitable such epoxy resins indude, for example but not to be limited to, those resins represented by formulas I, II, m, IV or V wherein each A is independently a divalent hydrocarbyl group having suitably from 1 to 12, more suitably from 1 to 6, most suitably from 1 to 4, carbon atoms; each A' is independenfly a divalent hydrocarbyl group having from 1 to 10, more suitably from 1 to 4, most suitably from 1 to 2, carbon atoms; each Q is independently hydrogen or an alkyl group having from 1 to 4 carbon atoms; each R is independently hydrogen or an alkyl group having from 1 to 3 carbon atoms; each X is independently hydrogen, a hydrocarbyl or hydrocarbyloxy group having suitably from 1 to 12, more suitably from 1 to 6, most suitably from 1 to 4, carbon atoms or a halogen atom, preferably chlorine or bromine; m has a value suitably from 0.01 to 8, more suitably from 1 to 6, most suitably from 2 to 4; n ' has a value of zero or 1; n' has an average value suitably from 0 to 200, more suitably from 0 to 150, most suitably from 0 to 100; each p suitably has a value from zero to 10, more suitably from 0 to 8, most suitably from 0 to 6; and each p' suitably has a value from zero to 8, more suitably from 1 to 6, most suitably from 2 to 4. The epoxy resins which are employed to prepare the phosphorylated and optionally fully or partially hydrolyzed epoxy resins of the present invention suitably have epoxide equivalent weights (EEWs) of from 90 to 100,000, more suitably from 170 to 50,000, most suitably from 400 to 25,000. Suitable curing agents which can be employed herein as component (D) include, for example, adducts of an imidazole such as 2-methylimidazole and an epoxy resin, alkylolated urea-aldehyde resins, alkylolated melamine-aldehyde epoxy resins, polyisocyanates, blocked polyisocyanates, alkylolated phenol-aldehyde resins, any combinations thereof. Particularly suitable curing agents include, for example, methylolated urea-formaldehyde resins, methylolated melamine-formaldehyde resins, methylolated phenol-formaldehyde resins, toluene diisocyanate, 4,4'-diphenylmethanediisocyanate, isophorone diisocyanate and its liquid derivatives sold under the trade names of Rubinate LF-168 or Rubinate LF-179 by Rubinate Chemicals, Inc. of Wilmington, Delaware, or ISONATE™ 143L or ISONATE™ 181 by The Dow Chemical Company of Midland, Michigan, a biuret or isocyanurate from hexamethylene diisocyanate, and a cyclic trimer of hexamethylene diisocyanate and toluene diisocyanate. The isocyanates can also be prepolymers of the aforementioned isocyanates and polyols such as polypropylene glycols, triols such as trimethylol-propane or glycerine or their reaction products with propylene oxide, butylene oxide or mixtures thereof having equivalent weights of from 85 to 1000. The isocyanates can be blocked with phenols, such as phenol, 4-chlorophenol, o-secbutylphenol, lactams such as caprolactam and ketoximes or aldoximes such as acetaldehyde oxime or methyl ethyl ketoxime, or any combination thereof. Coatings capable of being cured at room temperature can be obtained by use of the aforementioned isocyanates which contain no blocking agent. From an industrial standpoint, the blocked isocyanates are preferred since they will provide one package systems. The ketoxime or lactam blocked isocyanates are preferred from an ecology standpoint and for providing the appropriate cure temperatures. The curing agents are employed in any quantity which will effectively cure the phosphorylated and optionally, totally or partially hydrolyzed epoxy resin. Suitable such effective amounts will depend upon the particular epoxy resin being cured and the particular curing agent being employed; however, suitable such amounts can indude, for example from 1 to 90, more suitably from 4 to 50, most suitably from 4 to 30, percent by weight based upon the combined weight of components (A), (B) and (C). The compositions of the present invention can be blended with other materials such as, solvents, fillers, pigments, dyes, flow modifiers, thickeners, reinforcing agents, catalysts, or any combination thereof. Suitable organic solvents which can be employed herdn include, for example, alcohols, glycols, glycol ethers, ketones, aromatic hydrocarbons, cyclic ethers, esters, chlorinated hydrocarbons, or any combination thereof. Particularly suitable solvents include, for example, toluene, benzene, xylene, methyl ethyl ketone, methyl isobutyl ketone, diethylene glycol methyl ether, dipropylene glycol methyl ether, ethylene glycol hexyl ether, mixtures of acetone and mefhylene chloride, mixtures of alcohols and methylene chloride, any combination thereof and the like. The amount of solvent to be employed is practically any amount which provides the system with the desired viscosity. However, suitably such amounts indude, for example, from 0 to 90, more suitably from 10 to 80, most suitably from 20 to 80, parts by weight based upon the weight of resin. These additives are added in functionally equivalent amounts eg, the pigments and/or dyes are added in quantities which will provide the composition with the desired color; however, they are suitably employed in amounts of from 20 to 200, more suitably from 50 to 150, most suitably from 50 to 100 percent by weight based upon the weight of the resin and curing agent. The modifiers such as thickeners, flow modifiers and the like can be suitably employed in amounts of from 0.01 to 20, more suitably from 0.1 to 10, most suitably from 0.1 to 2 percent by weight based upon the wdght of resin and curing agent. Rei fordng materials which can be employed herein include natural and synthetic fibers in the form of woven, mat, monofϊlament, multifilament, and the like. Suitable reinforcing materials indude, glass, ceramics, nylon, rayon, cotton, aramid, graphite, or any combination thereof. Suitable fillers which can be employed herein include, for example, inorganic oxides, ceramic microspheres, plastic microspheres, or any combination thereof. The fillers can be employed in amounts suitably from 5 to 100, more suitably from 10 to 50, most suitably from 10 to 30 percent by weight based upon the weight of the resin and curing agent. The following examples are illustrative of the invention and are not to be construed as to limiting the scope thereof in any manner. The following materials were employed in the Examples and Comparative Experiments. Epoxy Resin A was a bisphenol A based epoxy resin having an epoxide equivalent weight (EEW) of 3,000, a Gardner-Holdt viscosity at 40 percent non volatiles in diethylene glycol n-butyl ether at 25°C of Z3-Z5, a Gardner color of 2, and a Durran's softening point of 142°C-160°C commerdally available from The Dow Chemical Company as D.E.R.™ 669E. Epoxy Resin B was a bisphenol A based epoxy resin having an epoxide equivalent weight (EEW) of 1755, a melt viscosity at 25°C of 30,000 - 100,000 centistokes (30 - 100 Pas), a Gardner color @ 40 percent non-volatiles in diethyleneglycol n-butyl ether of 3, and a Durran's softening point of 120°C-135°C which was commerdally available from The Dow Chemical Company as D.E.R.™ 667. Epoxy Resin C was prepared in the following manner.: Into a 5-neck, 2-liter glass reactor equipped with stirrer, temperature controller, heating mantle and nitrogen purge means was charged 716 gms (3.978 equiv.) of a liquid diglyddyl ether of bisphenol A having an epoxide equivalent wdght (EEW) of 170, 79.5 gms (0.248 equiv.) of a liquid diglyddyl ether of polyoxypropylene glycol having an EEW of 321 and 407.5 gms (3.575 equiv) of bisphenol A. The mixture was thoroughly mixed under a nitrogen pad, then heated to 100°C followed by the addition of 1.35 gms (0.0033 equiv.) of 70 percent methanol solution of ethyltriphenyl phosphonium acetate-acetic add complex as a catalyst and the mixture was heated to 150°C and the mixture was allowed to exotherm to a temperature of 200°C. The temperature was maintained at 190°C-200°C for 1 hour and the final product was then flaked on aluminum foil. The resultant epoxy resin had an EEW of 1630. Phenolic Hydroxyl Terminated Resin A was prepared in the following manner. Into a suitable reaction vessd was weighed 230.0 grams (2.015 equiv.) of bisphenol-A and 270.0 grams (1.489 equiv.) of D.E.R._383, a liquid epoxy resin based on bisphenol A (diglyddyl ether of bisphenol A) commerdally available from The Dow Chemical Company having a percent epoxide of 23.71 percent (EEW 181.36), viscosity at 25 C C of 9,000-10,500 cps (9-10-5 Pas), and an APHA color of 125. The stirred mixture was padded with nitrogen and heated at a rate of 2°C to 4°C per minute to 60°C and then 0.4 grams of a 70 percent solution of ethyltriphenyl phosphonium acetate-acetic add complex catalyst in methanol was added. The mixture was heated to 180°C and hdd for 2 hours to react out all the epoxy resin. Then the mixture was cooled to 150°C and 500 grams of ethylene glycol n-butyl ether was added dropwise through an addition funnel and poured into a container. The resulting resin had a phenolic equivalent weight of 965. Phenolic Hvdroxyl Terminated Resin B was prepared in the the same manner as Phenolic Hydroxyl Terminated Resin B except that 152 grams (1.34 equiv.) of bisphenol A was reacted with 180 grams (1 equiv.) of the diglycidyl ether of bisphenol A. The resultant phenolic hydroxyl terminated resin had a phenolic hydroxyl equivalent weight of 360. Epoxy Phosphate Ester Resin was prepared in the following manner. This resin was prepared by the phosphorylation of a 50 percent solution of Epoxy Resin A in ethylene glycol n-butyl ether with 0.82 percent phosphoric acid by weight at 125°C for 45 minutes followed by hydrolysis with 2 percent water by weight for 2 hours at 125°C to give predominately the monoester phosphate resin having an percent epoxide of <0.01. Resin Blend A was a mixture of 40.5 parts by weight (pbw) of Epoxy Resin A, 19 pbw of Phenolic Hydroxyl Terminated Resin A, and 40.5 pbw of ethylene glycol n-butyl ether. Resin Blend B was a mixture of 30 parts by weight (pbw) of Epoxy Phosphate Ester Resin, 40 pbw of Resin Blend A and 30 pbw of ethylene glycol n-butyl ether. Curing Agent A was Methylon_75108, a commercial converting resin available from BTL Spedality Resins Corp. consisting of a mixture of allyl ethers of mono-, di- and tri-methylolphenol having a viscosity at 25°C of 2,000-4,000 centipoises (2-4 Pa s). Curing Agent B was EPON Curing Agent P-101 having a melt viscosity at 150°C of 40 poise (4 Pas) commerdally available from Shell Chemical Company. This curing agent was believed to be an adduct of 2-methyl imidazole and an epoxy resin as described by Klaren et al. in US Patent 3,756,984. How Modifier A was a silicone-free acrylic resin flow modifier available from BYK Chemie as BYK_-361 having a density of 1-1.06 g/cm3, flash point (Setaflash) of >100°C. Varnish Formulation A was prepared in the following manner. The resins were dissolved in a solvent blend of 90 percent ethylene glycol n-butyl ether/10 percent n-butanol to give a 40 percent solids resin solution. The resin solutions were formulated to give a solution containing 20 percent by weight of Curing agent A, 0.8 weight percent of phosphoric acid (85 percent H3PO4) accelerator, and 0.05 percent by weight of silicone flow modifier A. Ford #4 Cup viscosity determinations at 25°C were made on the formulated varnishes at 40 percent solids for comparison of resin types. Additional solvent blend of ethylene glycol n-butyl ether /n-butanol was added to give a solution viscosity of 100 seconds on the Ford #4 cup viscosity. The varnish samples were aged for at least 24 hours before applying to the substrate. Master Formulation A was prepared in the following manner. Into a 8 ounce glass jar was weighed 84.72 gms (0.048 equiv. of Epoxy Resin B and 18.57 gms (0.0516 phenolic hydroxyl equiv.) of a 40 percent nonvolatile solution of phenolic hydroxyl terminated resin B, said solution having a phenolic hydroxyl equivalent wdght of 360. The volatile portion of phenolic hydroxyl terminated resin B was a solvent blend consisting of 3 parts by weight (pbw) of propylene glycol methyl ether acetate, 2 pbw of xylene, 2 pbw of Aromatic 100 (a high purity narrow cut aromatic solvent containing a minimum aromatic content of 96 percent by wdght commerdally available form Exxon Chemical Company), 2 pbw of cyclohexanone and 1 pbw of n-Butanol by volume.3.87 gms of EPON™ Curing Agent P-101 (an epoxy resin curing agent having a melt viscosity at 150°C of 40 poise (4Pa-s) commerdally available from Shell Chemical Company) was added to the mixture which was then further diluted with 167.6 gms of the above mentioned solvent blend to produce the master formulation. The master formulation was then agitated thoroughly with an air-driven roller until everything was dissolved. Procedure for Coating Substrates was as follows: All pands were rinsed with Aromatic 100 (a high purity, 96 percent minimum, aromatic solvent commerdally available from Exxon Chemical Company) and baked at 400°F (204.4°C) for 10 minutes to degrease. Coatings were made on tinfree steel substrate using an appropriate wire wound rod. The panels were then baked in the oven at 400°F (204.4°C) for 10 minutes to yield the appropriate dry film thickness of 0.2 mils (0.00508 mm). The pands were then cured in a forced-air Blue M convection oven at 400°F (204.4°C) for 10 minutes. The panels were removed immediately from the oven after cure and allowed to cool down at room temperature 25°C The following test procedures were employed in the testing of the coatings. FILM THICKNESS ' Him thickness was determined by using a Fischer Multiscope. This tester determines film thickness by using magnetic properties of the steel substrate calibrated against a standard on the bare (film free) substrate. Each panel had an average of fifteen measurements to determine the thickness of the panel. The range for acceptable coating thickness was approximately 0.15-0.25 mils. ACETONE RESISTANCE Acetone double rubs were determined by rubbing the coating surface in a back and forth motion using a gloved index finger with which was wrapped with cheese cloth that was saturated with acetone. Counting was ceased when the coating surface was damaged. The number of acetone double rubs was noted. METHYL ETHYL KETONE RESISTANCE Methyl ethyl ketone (MEK) double rubs were determined by rubbing the coated surface with a 2-pound ball-pen hammer that had cheesecloth (10 plys of mesh 28 x 24) wrapped around the ball. The cheesecloth was saturated with MEK. Only the weight of the hammer and the force needed to guide the hammer across the coatings was used to rub the test panel back and forth at a rate of approximately 100 double rubs per minute. The rubs were counted (one forward and one backward to be counted as one double rub) and continued until, failure of the film or upon reaching 100 double rubs. Failure consists of removal of the film to expose the substrate at any spot along the center of the stroke. T-BEND FLEXIBILITY T-bend performance of coatings were determined according to ASTM-4145-83. A 2-inch width of the test panel was cut out of the center of the panel. The panel was first bent 0.5 to 0.75 inch from the end of the specimen in a fingerbrake, and inserted in the jaws of a vise to complete the initial 180 degree bend, known as OT bend. This first bend was OT because there was no panel sandwiched between the two outer layers of the panel. The panel was taped with Scotch 610 tape along the edge and tested for adhesion by removing the tape in rapid smooth motion. Bare metal was visualized by using a solution of 10 percent 1SO4 in IN HQ. This process of bending the panel via the fingerbrake and vise back on itself was continued until there was no sign of cracking or loss of adhesion. Each successive bend was known as IT, 2T, 3T, and so oh because of the layers of the panel that were sandwiched between the outer layers of the panel. Each successive bend placing less demand on the coating. The tested area of the panel was examined under a 30X microscope to determine crazing or pinhole types of failure. The edge area was discounted. The lower the number of the T-bend passed, the better the flexibility. WEDGE BEND FLEXIBILITY Another method for measuring the flexibility was by evaluating wedge bends by a modified ASTM D3281-84 test. The modification was as follows: Adhesive tape (Permacel, Avery International Co.) was applied to the wedgebend and removed rapidly. The formed wedgebend sample was immersed in acidic copper sulfate for 60 sec. to highlight bare metal, washed with deionized water and dried with a paper towel. The bend was examined under a 8X microscope. The tests were run across the grain of the metal. The length of the failure was measured and the number of millimeters failure was reported as a measure of wedge bend flexibility. CAN STAMPER EVALUATION A Biagosch & Brandau Can Stamper was used for our evaluation. This machine had a whed-driven 35 ton press and a spedal die for the production of square cups with four differential corners (radius 5-10-15-20 mm). The coated tinplate panels were lubricated externally with a wax, placed into the stamping machine and stamped to form a square cup with four differential corners. Corner A had the sharpest bend and the most severe testing. Corner D had the widest bend and the least deformation. For the initial rating, each of the four corners were examined and rated in the following manner: Rating Description 1 No scratches, smooth surface 2 Scratches, rough surface 3 Metal starting to show through 4 Whole section of metal showing with a length of < 0.8 mm. 5 Whole section of metal showing with a length of 0.8 - 1.2 mm. 6 Whole section of metal showing with a length of 1.3 - 1.4 mm. 7 Whole section of metal showing with a length of 1.5 - 1.8 mm. 8 Whole section of metal showing with a length of > 1.8 mm. The four digit rating was given as A B C D indicating the state of each corner starting with the sharpest corner A. An example of the rating would be 8531 since a higher number was usually found on the sharpest corner. CAN STAMPER EVALUATION AFTER LACTIC ACID STERILIZATION An even more stringent test was used to evaluate not only the formability characteristics of a coating but also its add resistance. Can cups from the process listed above were placed into 2 liter fruit jar containing a solution of 2 percent lactic add. The jars were then placed into metal jackets for safety precautions. The spedmens were then heated under pressure for a period of 90 minutes after reaching 121°C. The spedmens were then taken out, cooled and washed with distilled water. The four corners were then evaluated in the same manner as the method described above and rated accordingly. The four digit rating was again given as A B C D indicating the state of each corner after lactic add sterilization starting with the sharpest corner A. ' CROSS HATCH ADHESION EVALUATION AFTER LACTIC ACID STERILIZATION The film on the coated tinplate panel was cut at 1 mm x 1 mm to give 100 squares in 1 square centimeter using an NT cutter knife. The edge of the NT cutter was applied to reach the surface of the metal panel. The cutting speed was about 0.5 second per each cutting line. A vertical and horizontal cut was made. The square was taped with Scotch brand #610 tape and pulled off quickly. The coating was rated by percent of the squares not affected. The above method was also used on panels which have been subjected to sterilization with 2 percent lactic acid for 90 minutes at 121°C. The coating was cut and tested after sterilization. The sterilized coating was also rated by the percent of the squares not affected. T-PEEL ADHESION TEST All adhesion data were measured by T-peel test (ASTM D1876-72) using an Instron instrument. The T-peel tests strips were prepared by first cutting the cured panels into 5mm wide strips. Next, a strip of thermoplastic adhesive was placed between two panel strips with the coatings fadng the adhesive. Each unit was then heat bonded under a pressure of 150 psig at a temperature of 205°C for about 30 sec. The panels were then tested for dry adhesion using the Instron for a T-peel test. Wet adhesion was measured in the same manner after the testing specimen was soaked in 90°C water for four days. Results were reported as kg/5mm. The number reported was the force in kg (5mm sample width) needed to pull the strips apart. The higher the number, the better the coating. EXAMPLE 1 A varnish was prepared using Varnish Formulation A and Resin Blend B. Curing agent A was employed in an amount of 20 percent by weight. Substrates were coated employing Coating Procedure A. The formulation is given in Table I and the results are given in Table II. COMPARATIVE EXPERIMENT A A varnish was prepared using Varnish Formulation A from Epoxy Resin A. Curing agent A was employed in an amount of 20 percent by weight. Substrates were coated employing Coating Procedure A. The formulation is given in Table I and the results are given in Table II. COMPARATIVE EXPERIMENT B A varnish was prepared using Varnish Formulation A from resin blend A. Curing agent A was employed in an amount of 20 percent by weight. Substrates were coated employing Coating Procedure A. The formulation is given in Table I and the results are given in Table II. COMPARATIVE EXPERIMENT C A varnish was prepared using Varnish Formulation A from Epoxy Phosphate Ester Resin. Curing agent A was employed in an amount of 20 percent by weight. Substrates were coated and cured as described previously. The formulation is given in Table I and the results are given in Table II. EXAMPLE 2 An optimized varnish was prepared using Varnish Formulation A and 28 grams of Epoxy Resin A, 35 grams of phenolic terminated resin A, and 13.5 grams of Epoxy Phosphate Ester Resin. Curing agent A was employed in an amount of 10 percent by weight. Substrates were coated employing Coating Procedure A. The formulation is given in Table I and the results are given in Table H. Table I Ex.2 28 9.33 3.5 3.63 13.5 0 0 45 26.5 75 Not an example of the present invention. Percent by weight based on wdght of Epoxy Resin + Hydroxyl Terminated Resin + Epoxy Phosphate Ester Resin + Curing Agent. Percent by weight based on total weight of the formulation. Required as a catalyst in comparative experiments A and B since there was no phosphorous compound present. Table II Ex.2 Z5-Z6 8 1111 2111 100 19 * Not an example of the present invention. a Before sterilization, k After sterilization. EXAMPLE 3 A portion of Master Formulation A was wdghed into a 2 ounce (59.1 mL) glass jar and a 60 percent non-volatile solution of Epoxy Phosphate Ester Resin in ethylene glycol n-butyl ether was added. The mixture was then mixed thoroughly on an air-driven roller and aged for 24 hours before use. Procedure B for coating substrates was employed. The formulation is given in Table HI and the results are given in Table IV. EXAMPLE 4 In an identical manner as described in Example 3 except one-half as much of the ]60 percent non-volatile solution in Ethylene glycol n-butyl ether of Epoxy Phosphate Ester Resin was used. The formulation ias given in Table HI and the results are given in Table IV. COMPARATIVE EXPERIMENT D In a manner identical to that described in Example 3 but no epoxy ' phosphate ester resin was added to the formulation. The formulation is given in Table III and the results are given in Table IV. COMPARATIVE EXPERIMENT E 60 gms of a 50 percent non-volatile solution in ethylene glycol n-butyl ether of Epoxy Resin B was weighed in a 4 ounce (118.3 mL) glass jar and 43 gms of ethylene glycol n-butyl ether was added to dilute the solution.0.21 gms of 85 percent by weight of phosphoric add in aqueous solution was added, then 6.12 gms of Curing Agent A was added. The formulation was thoroughly agitated on an air-driven roller for 2 hours then aged 24 hours before use. Coated panels were prepared and tested according to the procedure described in Example 3. The formulation is given in Table III and the results are given in Table IV. COMPARATIVE EXPERIMENT F In a manner similar to comparative experiment E, 50 gms of Epoxy Phosphate Ester Resin solution (60 percent non-volatile in ethylene glycol n-butyl ether) was weighed into a 4 ounce (118.3 mL) glass jar then 6.12 gms of Curing Agent A and 0.21 gms of 85 percent non-volatile phosphoric add solution added. The formulation was then diluted with 43 gms of ethylene glycol n-butyl ether, agitated thoroughly and aged for 24 hrs before use. Panels were coated and tested according to procedures described in Example 3. The formulation was given in Table III and the results are given in Table IV. EXAMPLES In a manner identical to example 3 except tlie epoxy resin used was Epoxy Resin C having an epoxide equivalent weight of 1,630. 32.60 gms (0.02 equiv.) of a 40 percent non-volatile solution of epoxy resin in a solvent blend consisting of 3 parts by weight (pbw) of propylene glycol methyl ether acetate, 2 part by volume (pbv) of xylene, 2 pbv of Aromatic 100 (a high purity, 96 percent minimum, aromatic solvent commerdally available from Exxon Chemical Company), 2 pbv of cyclohexanone and 1 pbv of n-butanol was used along with 1.55 gms of a 60 percent non-volatile solution of Epoxy Phosphate Ester B in ethylene glycol n-butyl ether. The formulation was given in Table III and the results are given in Table IV. Not an example of the present invention. Table IV Not an example of the present invention As the results in Table IV indicate, the combination of epoxy phosphate ester with an epoxy resin, a phenolic capped resin advancement agent and an imidazole type catalyst/curing agent provided the superior formability while retaining traditional epoxy protection properties. As shown in Examples 3 and 4, these formulations exhibited excellent flexibility (TO bend and no wedge bend loss) while retaining excellent solvent resistance (60 MEK rubs) and adhesion properties. The traditional formulations used widely in the art which are shown in Comparative Experiments E and F do not have the flexibility required (T3 and T2 bend, respectively and 25 and 15 mm wedge bend losses, respectively) to pass the 2-piece can forming process. A value of TO-Tl was required for the 2-piece can forming process. The formulation in Comparative Experiment D shows good flexibility but suffers from poor dry and wet adhesion, which reduces the process resistance properties of the coating.

Claims: Claims: 1. A composition characterized by a blend or mixture comprising (A) at least one compound containing an average of more than one vidnal epoxide group per molecule; ( B ) at least one compound containing an average of 2 phenolic hydroxyl groups per molecule; and (C) at least one epoxy phosphate ester; wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 20:1; and component (C) is present in an amount of from 5 to 80 percent by weight based on the combined weight of components (A and B). 2. A curable composition characterized by a blend or mixture comprising ( A ) at least one compound containing an average of more than one vidnal epoxide group per molecule; ( B ) at least one compound containing an average of 2 phenolic hydroxyl groups per molecule; and (C) at least one epoxy phosphate ester; and (D) a curing amount of at least one curing agent; wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 20:1; component (C) is present in an amount of from 1 to 80 percent by weight based on the combined weight of components (A and B); and component (D) is present in an amount of from 0.5 to 60 percent by weight based on the combined weight of components (A), (B), (C) and (D). 3. A coating composition characterized by a mixture or blend of (I) a curable composition comprising a blend or mixture of ( A ) at least one compound containing an average of more than one vicinal epoxide group per molecule; ( B ) at least one compound containing an average of abut 2 phenolic hydroxyl group per molecule; and (C) at least one epoxy phosphate ester; and (D ) a curing amount of at least one curing agent; and (II) an inert carrier or solvent; wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 20:1; component (C) is present in an amount of from 1 to 80 percent by wdght based on the combined weight of components (A and B); component (D) is present in an amount of from 0.5 to 60 percent by weight based on the combined wdght of components (A), (B), (C) and (D); and component II is present in an amount of from 10 to 90 percent by wdght based upon the combined amount of components (I) and (II). 4. A composition, curable composition or coating composition of Claims 1, 2 or 3 wherein components (A) and (B) -ire present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 0.8:1; component (C) is present in an amount of from 10 to 50 percent by wdght based on the combined wdght of components (A and B); component (D) is present in an amount of from 2 to 30 percent by wdght based on the combined weight of components (A), (B), (C) and (D); and component π is present in an amount of from 20 to 80 percent by wdght based upon the combined amount of components 0) and (-0). 5. A composition, curable composition or coating composition of Claims 1, 2 or 3 wherein components (A) and (B) are present in an amount which provides a ratio of phenolic hydroxyl groups per epoxide group of from 0.05:1 to 0.6:1; component (C) is present in an amount of from 15 to 30 percent by wdght based on the combined wdght of components (A and B); component (D) is present in an amount of from 2 to 20 percent by wdght based on the combined weight of components (A), (B), (C) and (D); and component II is present in an amount of from 35 to 75 percent by wdght based upon the combined amount of components (I) and (H). 6. A composition, curable composition or coating composition of Claims 1, 2, 3, or 5 wherein (a ) component (A) is selected from the group consisting of glyddyl ethers of dihydric phenols, advanced epoxy resins prepared by reacting a diglyddyl ether of a dihydric phenol with a dihydric phenol which may be the same or different from the dihydric phenol in the diglyddyl ether of a dihydric phenol, glyddyl ethers of alkylene oxide adducts of dihydric phenols, advanced epoxy resins prepared by reacting glyddyl ethers of alkylene oxide adducts of dihydric phenols with a dihydric phenol or an alkylene oxide adduct of a dihydric phenol wherein the dihydric phenols in each instance can be the f same or different; (b) component (B) is a compound represented by formulas I and II Formula I Formula π wherein each A is independently a divalent hydrocarbyl group having from 1 to 12 carbon atoms; each R is independently hydrogen or an alkyl group having from 1 to 3 carbon atoms; each X is independently hydrogen, a hydrocarbyl or hydrocarbyloxy group having from 1 to 12 carbon atoms or a halogen atom; Z is hydrogen; n has a value of zero or 1; and n' has an average value from 2 to 90; (c) component (C) is a compound prepared by reacting a phosphoric add or phosphoric add ester source with an epoxy-containing compound selected from the group consisting of glycidyl ethers of dihydric phenols, advanced epoxy resins prepared by reacting a diglyddyl ether of a dihydric phenol with a dihydric phenol which may be the same or different from the dihydric phenol in the diglycidyl ether of a dihydric phenol, glycidyl ethers of alkylene oxide adducts of dihydric phenols, advanced epoxy resins prepared by reacting glycidyl ethers of alkylene oxide adducts of dihydric phenols with a dihydric phenol or an alkylene oxide adduct of a dihydric phenol wherein the dihydric phenols in each instance can be the same or different; (d) component (D) is an imidazole-epoxy resin adduct, alkylolated urea-aldehyde resin, alkylolated melamine-aldehyde resin, alkylolated phenol-aldehyde reson, blocked polyisocyanate or any combination thereof; and (e) component (II) is an alcohol, glycol, glycol ether, ketone, aromatic hydrocarbon, cyclic ether, ester, chlorinated hydrocarbon or any combination thereof. 7. A composition, curable composition or coating composition of Claims 1, 2, 3, 4, 5 or 6 wherein (a) component (A) is a diglycidyl ether of bisphenol A, a diglycidyl ether of bisphenol F or a diglycidyl ether of bisphenol K having an epoxide equivalent weight of from 500 to 4,000; (b) component (B) is a phenolic hydroxyl terminated product resulting from reacting (1) a diglyddyl ether of bisphenol A, a diglyddyl ether of bisphenol F or a diglycidyl ether of bisphenol K having an epoxide equivalent weight of from 500 to 3,000, with (2) bisphenol A, bisphenol F or bisphenol K; and (c) component (C) is a partially or totally hydrolyzed reaction product of (1) a diglyddyl ether of bisphenol A, a diglyddyl ether of bisphenol F or a diglycidyl ether of bisphenol K having an epoxide equivalent wdght of from 500 to 3,000, and (2) a phosphoric add source or a phosphoric add ester source.

Inventors: MASSINGILL JOHN LEE, PHAM HA QUOC, RIPPLE SUSAN D, MASSINGILL, JOHN, LEE, PHAM, HA, QUOC, RIPPLE, SUSAN, D.
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1993
Main classification: C08G59
IPC codes: C08G59, C09D163