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
  • C08G59/4292—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof together with monocarboxylic acids
• • 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

• the present invention relates to water soluble epoxy ester copolymers which are particularly adapted to sanitary can use where good resistance to extraction by hot water and good odor and flavor characteristics are essential.
• Background Art Water solution coating compositions have been employed for diverse purposes, but it has been difficult to obtain the good resistance to extraction by hot water and good odor and flavor characteristics which are important to enable application of the coatings to sanitary cans.
• a relatively low molecular. weight polyepoxide having an average molecular weight of about 300 to about 1100 (by calculation) and a 1, 2-epoxy equivalency of about 1.4 to about 2.0 is esterified with an at least approximately stoichio-metric proportion, based on epoxide functionality, of monocarboxylic acid selected from benzoic acid, a C 1 -C 8 alkyl substituted benzoic acid, or a C 6 -C 10 alkanoic acid to produce an ester derivative substantially free of epoxy functionality.
• This esterification reaction is continued to an acid number of less than 20.
• the resulting hydroxy functional epoxy ester is then polyesterified with a monoethylenic dicarboxylic acid which resists homopolymerization, preferably fumaric acid.
• polyesterification reaction From 1.5-8% of the diacid is used in the polyesterification reaction, based on the weight, of the epoxy ester, so the hydroxy groups in the epoxy ester are present in stoichiometric excess, and the polyesterification is continued to an acid number of less than 20 to provide an ethylenically unsaturated hydroxy functional poly- ester.
• This unsaturated polyester is then copolymerized with from 15% to 70% of monoethylenic monomers, based on the weight of the copolymer, to provide a copolymer product.
• These monomers include monoethylenic carboxylic acid, such as methacrylic acid or fumaric acid, to provide an acid number of from 20-100 in the final copolymer so that amine and water can be added to provide a water dispersion which is either a solution or a colloidal dispersion.
• Reactive monomers such as hydroxyethyl acrylate or N-methylol acrylamide or its ether, such as the butyl ether, may be used.
• an aminoplast such as hexamethoxy methyl melamine, or a water soluble or dispersible phenoplast, or a mixture thereof, may be used for cure.
• the polyepoxides preferably have a 1, 2-epoxy equivalency of about 1.4 to about 2.0 and the best properties are obtained using diglycidyl ethers of a bisphenol, such as bisphenol A.
• the preferred molecular weight of the polyepoxides which may be provided by the use of mixtures, is from 350 to 800.
• the saturated monocarboxylie acid used to consume the epoxy functionality may be benzoic acid or a C 1 -C 8 alkyl substituted benzoic acid or a C 6 -C 10 alkanoic acid, but para tertiary butyl benzoic acid is particularly preferred.
• the C 6 -C 10 alkanoic acids are less preferred and are illustrated by hexoic acid or pelar- gonic acid.
• These saturated monocarboxylic acids uniquely provide maximum impermeability in the combination of this invention.
• the esterification reaction is wholly conventional, simple heating to a hot melt, desirably in the presence of a trace of amine catalyst, being all that is needed.
• the acid is used in at least approximately stoichiometric proportion and the reaction is continued to consume most of the acid, an acid number of less than about 20, preferably less than 10, being contemplated.
• Significant residual epoxy functionality yields instability and should be avoided. Some excess acid will simply react with the hydroxy functionality on the epoxy ester. It is here noted that polyepoxides frequently contain hydroxy groups, and even if they do not, the carboxy-epoxy reaction produces hydroxy groups, so the epoxy ester which is formed is hydroxy functional. Substantially stoichiometric proportions are preferred.
• the monoethylenically unsaturated dicarboxylic acid should resist homopolymerization so that its acidity can be substantially consumbed in the production of a polyester with the hydroxyl functional epoxy ester without consuming the unsaturation.
• the preferred dicarboxylic acid is fumaric acid, but maleic acid or maleic anhydride can also be used.
• This polyester now contains polymerizable unsaturation and it is copolymerized with monoethylenic monomers, the bulk of which (at least about 50% by weight) are nonreactive. This means that, aside from their polymerizable unsaturation, they do not react under the conditions of polymerization and use which are contemplated. A similar statement is that there are no functional groups except the polymerizable ethylenic group. Styrene and vinyl toluene are particularly contemplated, though methyl methacrylate, methyl acrylate, ethyl acrylate, acrylonitrile and vinyl acetate will further illustrate the useful materials. Styrene and vinyl toluene are especially important for two reasons.
• a monoethylenic carboxylic acid of any desired type should be employed to provide an acid number of from 20-100 in the final copolymer. Fumaric acid and maleic acid are preferred because these are F.D.A. approved, but acrylic acid, methacrylic acid, crotonic acid and itaconic acid are all useful, and one cannot know which acids will be a-proved for sanitary can use in the future. Maleic anhydride is useful at the smaller proportion of use.
• the preferred acidity should not exceed 60. While more acid polymers can be used, sanitary can use requires maximum water resistance and good resistance to water extraction, and these are best at low acid value.
• the copolymers herein are well adapted to disperse in water at low acid value.
• Other reactive monoethylenic monomers may be included in an amount up to about 20% of the total polymerizable monomers. These are illustrated by hydroxy monomers, such as 2-hydroxyethyl acrylate, amide monomers, such as acrylamide, N-methylol functional monomers, such as N-methylol acrylamide or ethers thereof like the butyl ether.
• the copolymerization is itself conventional being carried out in organic solvent solution using a free radical generating polymerization catalyst. These are well known and are illustrated in the Example.
• aminoplast and phenoplast resins which may be used for cure are also well known and will be illustrated by hexamethoxymethyl melamine.
• This class of water soluble and water dispersible materials useful for curing hydroxy functional resins is a matter of common knowledge in the art. They are used in an amount of 5-40% of total resin solids.
• An amine including ammonia, is added to allow the acidic copolymer to be dispersed in water. This is again conventional, and is illustrated using dimethyl ethanol amine.
• the resulting aqueous solutions cure to provide films characterized by superior resistance to extraction and they resist absorbing odor and flavor components of the foods and beverages which are packaged. They can be applied to any metal can interior, such as aluminum, steel and tin plated steel. Spray appication and cure by baking at 400°F. for 3 minutes are particularly contemplated. Films of about 0.2-0.3 mil are formed. Good adhesion is obtained on all of these surfaces.
• the final product is a milky dispersion having the following characteristics: Nonvolatile solids 30.1%; Acid value of solids - 33.5.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Paints Or Removers (AREA)
• Macromonomer-Based Addition Polymer (AREA)

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• 1979
  • 1979-03-09 JP JP50051479A patent/JPS55500154A/ja active Pending
  • 1979-03-09 WO PCT/US1979/000110 patent/WO1979000732A1/en unknown
  • 1979-03-09 CA CA000323074A patent/CA1117690A/en not_active Expired
  • 1979-10-09 EP EP79900275A patent/EP0015917A1/en not_active Withdrawn

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