JP2016011333A - Coating composition for food contact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition for can inner surface food contact containing no resin produced by using bisphenol A and a raw material containing bisphenol A, excellent in storage stability of coating and enabling a coating film excellent in water resistance, food resistance and processability to be formed.SOLUTION: The coating composition for food contact is provided which contains an emulsion of a composite vinyl polymer (B) obtained by emulsification polymerizing an unsaturated monomer (b) in the presence of a solution or a fluid dispersion of a vinyl polymer (A) having a carboxyl group of which all or a part may be neutralized and a radical reactive unsaturated group. In the coating composition for food contact, the solid content of the vinyl polymer (A) contained in 100 pts.mass of the solid content of the composite vinyl polymer (B) is in the range of 5 to 80 pts.mass and the glass transition temperature of the polymer of the unsaturated monomer (b) is in the range of -50 to 90°C.

Description

  The present invention relates to a coating composition for food contact, which is excellent in storage stability of a paint and can form a coating film excellent in water resistance, corrosion resistance and processability.

  Conventionally, organic solvent-type paints containing bisphenol A type epoxy resins and phenolic resin curing agents have been generally used as paints for the inner surface of cans. However, there is a problem of global environmental pollution caused by organic solvents discharged from these paints. Yes, organic solvent-type paints are being replaced by water-based paints.

  As the aqueous paint, for example, an aqueous paint containing an epoxy-modified acrylic resin obtained by reacting an epoxy resin with a carboxyl group-containing acrylic resin has been proposed (see Patent Document 1).

  In the conventional water-based paint for inner surfaces of cans as described above, an epoxy resin produced using a raw material containing bisphenol A is generally used in order to obtain good coating workability and coating film performance. However, from the viewpoint of the influence on the global environment in recent years, a water-based coating for can inner surfaces which does not contain a resin manufactured using a raw material containing bisphenol A is desired. As a coating composition using a resin that does not use bisphenol A as a raw material, for example, a composite obtained by emulsion polymerization of an ethylenically unsaturated monomer using a carboxyl group-containing acrylic copolymer neutralized with a basic compound An aqueous coating composition for can inner surface coating containing a resin emulsion is disclosed (Patent Document 1). However, when the water-based paint contains an organic solvent as a film-forming aid, aggregates resulting from the resin emulsion are likely to be produced during production, production stability is poor, and retort resistance of the obtained coating film is poor. There was a thing.

  On the other hand, an aqueous coating composition using a resin emulsion obtained by coexisting an oxirane functional-containing monomer when an ethylenic monomer is emulsion-polymerized using a carboxyl group-containing acrylic copolymer neutralized with a basic compound Is disclosed (Patent Document 2). However, this paint has a problem that the reaction presumed to be caused by unreacted oxirane groups proceeds during storage and tends to thicken during storage.

  Aqueous coating for can inner surface comprising acrylic modified polyester resin obtained by graft polymerization of polymerizable unsaturated monomer containing carboxyl group-containing polymerizable unsaturated monomer to polyester having radical reactive unsaturated group, and resol type phenolic resin crosslinking A composition is disclosed (Patent Document 3). However, the film obtained from the above composition may be inferior in retort whitening resistance.

JP 2005-179491 A WO2006 / 045017 JP 2002-302039 A

  An object of the present invention is a coating composition for food contact that does not contain a resin produced using bisphenol A or a raw material containing bisphenol A, and has coating production stability, storage stability, and resistance to retort whitening of a coating film. An excellent food contact coating composition and a coated can formed by coating the coating composition.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a vinyl polymer (A) having a carboxyl group and a radical-reactive unsaturated group that may be partially or wholly neutralized. A coating composition for food contact comprising an emulsion of a composite vinyl polymer (B) obtained by emulsion polymerization of an unsaturated monomer (b) in the presence of an aqueous solution or dispersion of And the present invention was completed.

The present invention provides the following food-contact coating composition and a coated article obtained by coating the food-contact coating composition on an object to be coated.
Item 1. Emulsion polymerization of unsaturated monomer (b) in the presence of an aqueous solution or dispersion of vinyl polymer (A) having a carboxyl group and radical reactive unsaturated group which may be partially or fully neutralized A coating composition for food contact, comprising an emulsion of a composite vinyl polymer (B), wherein the vinyl polymer (A) is contained in 100 parts by mass of the solid content of the composite vinyl polymer (B). The food contact coating material, wherein the solid content is in the range of 5 to 80 parts by mass and the glass transition temperature of the polymer of the unsaturated monomer (b) is in the range of -50 to 90 ° C. Composition.
Item 2. The vinyl polymer (A) is obtained by reacting a vinyl polymer (C1) having a carboxyl group which may be partially or completely neutralized with a compound having an epoxy group and a radical reactive unsaturated group. Item 2. The food contact coating composition according to Item 1, wherein the coating composition is for food contact.
Item 3. The vinyl polymer (A) is a vinyl polymer (C2) having a carboxyl group and a hydroxyl group, which may be partially or wholly neutralized, and a compound having an isocyanate group and a radical reactive unsaturated group. Item 2. The food contact coating composition according to Item 1, which is reacted.
Item 4. The vinyl polymer (A) includes a vinyl polymer (C2) having a carboxyl group and a hydroxyl group, which may be partially or wholly neutralized, a polyisocyanate compound, a hydroxyl group and a radical reactive unsaturated group. Item 2. The food contact coating composition according to Item 1, which is obtained by reacting a mixture with a compound having the compound.
Item 5. Any of Items 1-4, further comprising a water-soluble or water-dispersible aqueous polymer (D) having a weight average molecular weight in the range of 3000 to 200,000 and a glass transition temperature of −20 ° C. or higher. The food contact coating composition according to claim 1.
Item 6. Item 6. The food contact coating composition according to Item 5, wherein the aqueous polymer (D) is a vinyl polymer (D1).
Item 7. Item 7. The food contact coating composition according to any one of Items 1 to 6, further comprising a resol type phenolic resin (E1) and / or an amino resin (E2).
Item 8. Item 8. The food contact coating composition according to any one of Items 1 to 7, wherein the food contact coating composition is a food contact coating composition for inner coating of a can.
Item 9. A coated can, wherein the inner surface of the can is coated with the food contact paint composition according to any one of Items 1 to 8.
Item 10. A coated can in which the inner surface of the lid of the can is coated with the food contact coating composition according to any one of Items 1 to 8.
Item 11. Item 8. A coated can, wherein the outer surface of the lid of the can is coated with the food contact coating composition according to item 1-7.

  The coating composition for food contact of the present invention is excellent in coating production stability, storage stability, and resistance to retort whitening of a coating film.

  The coating composition for food contact of the present invention (hereinafter sometimes referred to as “coating composition”) is a vinyl-based compound having a carboxyl group and a radical-reactive unsaturated group which may be partially or wholly neutralized. It contains an emulsion of a composite vinyl polymer (B) formed by emulsion polymerization of an unsaturated monomer (b) in the presence of an aqueous solution or dispersion of the polymer (A).

Vinyl polymer (A)
The vinyl polymer (A) having a carboxyl group and a radical reactive unsaturated group can be obtained by a known method. Specifically, for example, the following methods (1) to (5) can be mentioned.

(1) Reaction of a vinyl polymer (C1) having a carboxyl group with a compound having an epoxy group and a radical reactive unsaturated group
Examples of the compound having an epoxy group and a radical reactive unsaturated group include glycidyl (meth) acrylate and allyl glycidyl ether. The vinyl polymer (C1) having a carboxyl group is obtained, for example, by carrying out a copolymerization reaction between an unsaturated monomer having a carboxyl group and another unsaturated monomer using a radical polymerization initiator. be able to.

  The reaction between the vinyl polymer (C1) having a carboxyl group and the compound having an epoxy group and a radical reactive unsaturated group can be carried out at a reaction temperature in the range of about 20 to 150 ° C. This reaction may be performed in the presence of a known catalyst.

(2) Reaction of a vinyl polymer (C2) having a carboxyl group and a hydroxyl group with a compound having an isocyanate group and a radical reactive unsaturated group
Examples of the compound having an isocyanate group and a radical reactive unsaturated group include isocyanate alkyl (meta) such as isocyanate methyl (meth) acrylate, isocyanate ethyl (meth) acrylate, isocyanate propyl (meth) acrylate, and isocyanate octyl (meth) acrylate. ) Acrylate: p-methacryloxy-α, α′-dimethylbenzyl isocyanate, m-acryloxy-α, α′-dimethylbenzyl isocyanate, m- or p-isopropenyl-α, α′-dimethylbenzyl isocyanate and the like. Further, for example, a diisocyanate compound and a hydroxyalkyl (meth) acrylate are reacted with an isocyanate group of the diisocyanate compound and a hydroxyl group of the hydroxyalkyl (meth) acrylate in an equivalent ratio of 1.0: 0.5 to 1.0: 0.6. The compound which consists of is mentioned. Examples of the diisocyanate compound include isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, trimethylhexamethylene diisocyanate, and tetramethylxylylene diisocyanate. Examples of the hydroxyalkyl (meth) acrylate include alkyls such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Examples include hydroxyalkyl (meth) acrylates having 2 to 7 carbon atoms in the group. As said compound which has an isocyanate group and a radical reactive unsaturated group, the compound which has one ethylenically unsaturated group and one isocyanate group in 1 molecule is preferable.

  The vinyl polymer (C2) having a carboxyl group and a hydroxyl group is obtained by, for example, performing a copolymerization reaction between an unsaturated monomer having a hydroxyl group, an unsaturated monomer having a carboxyl group, and another unsaturated monomer. It can be obtained by using a radical polymerization initiator.

  The reaction of the vinyl polymer (C2) having a carboxyl group and a hydroxyl group with the compound having an isocyanate group and a radical reactive unsaturated group can be carried out at a reaction temperature in the range of about 0 to 150 ° C. This reaction may be performed in the presence of a known catalyst.

(3) Reaction of a mixture of a vinyl polymer (C2) having a carboxyl group and a hydroxyl group, a polyisocyanate compound, and a compound having a hydroxyl group and a radical reactive unsaturated group
The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, the polyisocyanate compound is a compound having two or more isocyanate groups in one molecule, and those conventionally used for the production of polyurethane can be used. Examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of these polyisocyanates.

  Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene. Aliphatic diisocyanates such as diisocyanates, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, eg lysine ester triisocyanate, 1,4,8-tri Isocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2, , And aliphatic triisocyanates, such as 7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl octane and the like.

  Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: Isophorone diisocyanate), 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane ( Common name: hydrogenated xylylene diisocyanate) or mixtures thereof, alicyclic diisocyanates such as norbornane diisocyanate, for example 1,3,5-triisocyanatocyclohexane, 1, , 5-trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 2- (3-isocyanatopropyl) -2 , 6-Di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanate Natomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyana Propyl) -bicyclo (2.2.1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, etc. And alicyclic triisocyanate.

  Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis ( 1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or an aromatic aliphatic diisocyanate such as a mixture thereof, for example, an araliphatic triisocyanate such as 1,3,5-triisocyanatomethylbenzene And so on.

  Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate or a mixture thereof. 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, for example, triphenylmethane-4,4 ′, 4 Aromatic triisocyanates such as '' '-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, such as 4,4'-diphenylmethane-2,2', 5 , 5'- Or the like can be mentioned aromatic tetracarboxylic isocyanates such as tiger isocyanate.

  Examples of the polyisocyanate derivative include dimer, trimer, biuret, allophanate, carbodiimide, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI). ) And Crude TDI.

  If necessary, the polyisocyanate compound may be obtained by modifying a part of the isocyanate group with a compound containing 1 to 5 active hydrogen groups such as a hydroxyl group or an amino group per molecule. The said polyisocyanate compound may be used independently and may be used together 2 or more types.

  The compound having a hydroxyl group and a radical reactive unsaturated group is a compound having at least one hydroxyl group and a radical reactive unsaturated group in one molecule. Examples of the compound include (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Monoesterified product of dihydric alcohol having 2 to 8 carbon atoms; ε-caprolactone modified product of monoesterified product of (meth) acrylic acid and dihydric alcohol having 2 to 8 carbon atoms; N-hydroxymethyl (meth) Examples include acrylamide; allyl alcohol, and (meth) acrylate having a polyoxyethylene chain whose molecular end is a hydroxyl group. These can be used alone or in combination of two or more.

  The reaction for obtaining the vinyl polymer (A) between the vinyl polymer (C2) having a carboxyl group and a hydroxyl group, the polyisocyanate compound, and the compound having a hydroxyl group and a radical reactive unsaturated group is about 0 to The reaction can be carried out in the presence of a known catalyst in the range of 150 ° C.

(4) Reaction of a vinyl polymer (C3) having a hydroxyl group with a compound having a carboxylic anhydride group and a radical reactive unsaturated group
Examples of the compound having a carboxylic anhydride group and a radical reactive unsaturated group include itaconic anhydride, maleic anhydride, and tetrahydrophthalic anhydride.

  The vinyl polymer (C3) having a hydroxyl group can be obtained, for example, by carrying out a copolymerization reaction of an unsaturated monomer having a hydroxyl group with another unsaturated monomer using a radical polymerization initiator. it can.

  The reaction of the vinyl polymer (C3) having a hydroxyl group and the compound having a carboxylic anhydride group and a radical reactive unsaturated group can be carried out at a reaction temperature in the range of about 0 to 150 ° C. This reaction may be performed in the presence of a known catalyst.

  The reactions in (1) to (4) are preferably performed in the presence of a radical polymerization inhibitor such as hydroquinone and p-methoxyphenol and / or in the presence of oxygen. Moreover, the said reaction can be performed in presence of a well-known solvent as needed. Examples of the solvent include known organic solvents such as water, toluene, butanol, methyl isobutyl ketone, and butyl cellosolve, and can be used alone or in combination of two or more.

(5) Other methods A vinyl polymer (A) may be obtained by polymerizing an unsaturated monomer having a carboxyl group by the following method. For example, a radical polymerization method using 2,4-diphenyl-4-methyl-1-pentene disclosed in JP-A-7-002954 as a reversible addition-cleavage type chain transfer agent, Japanese Patent Publication No. 6-23209 Catalytic Chain Transfer Polymerization using a cobalt complex disclosed in JP-B-7-35411 and the like, a high-temperature radical polymerization method disclosed in JP-A-2000-80288, etc. Since the vinyl polymer obtained by these polymerization methods has a radical reactive unsaturated group at one end, it can be used as the vinyl polymer (A) in the present invention. Can do.

  In addition, a polymer obtained by introducing a carboxyl group into the vinyl polymer by a reaction between a vinyl polymer having a radical reactive unsaturated group and a hydroxyl group obtained by a known method and a carboxylic acid anhydride compound is made vinyl. You may use as a system polymer (A). Examples of the carboxylic acid anhydride compound include maleic anhydride, itaconic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, and succinic anhydride.

  The polymerization reaction for obtaining the vinyl polymers (C1) to (C3) can be performed by a conventionally known radical polymerization method such as solution polymerization, dispersion polymerization, bulk polymerization and the like. In the polymerization reaction described in the above polymerization and the method (5), unsaturated monomers that can be used are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl ( (Meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t Alkyl or cycloalkyl (meth) acrylate such as butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate; unsaturated monomer having an isobornyl group such as isobornyl (meth) acrylate; adamantyl (meth) acrylate Unsaturated monomers having an adamantyl group such as styrene, α-methylstyrene, vinyltoluene compounds such as vinyltoluene; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- ( Unsaturated monomer having alkoxysilyl group such as meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane; perfluorobutylethyl (meth) acrylate, perfluorooctylethyl Perfluoroalkyl (meth) acrylates such as meth) acrylate; unsaturated monomers having a fluorinated alkyl group such as fluoroolefin; N-substituted maleimides; N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, acetic acid Vinyl compounds such as vinyl; carboxyl group-containing unsaturated monomers such as (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, crotonic acid, and β-carboxyethyl (meth) acrylate ; (Meth) acrylonitrile, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meth) acryloylmorpholine, N-isopropyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-alkoxymethyl (meth) Acry Nitrogen-containing unsaturated monomers such as amides, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, adducts of glycidyl (meth) acrylate and amines; (Meth) acrylic acid such as hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2 to 8 carbon atoms Monoesterified product of dihydric alcohol and ε-caprolactone modified product of monoesterified product of (meth) acrylic acid and dihydric alcohol having 2 to 8 carbon atoms, allyl alcohol, polyoxyethylene whose molecular terminal is a hydroxyl group Hydroxyl-containing unsaturated monomers such as (meth) acrylate having a chain; glycidyl (meth) acrylate Relate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether Epoxy group-containing unsaturated monomers such as: (meth) acrylates having polyoxyethylene chains whose molecular ends are alkoxy groups; 2- (meth) acrylamide-2-methylpropanesulfonic acid, allylsulfonic acid, styrenesulfonic acid Sulfonic acid group-containing unsaturated monomers such as sulfoethyl (meth) acrylate and sodium salts or ammonium salts thereof; unsaturated monomers having a phosphoric acid group such as 2- (meth) acryloyloxyethyl acid phosphate; , Carbonyl group-containing unsaturation such as diacetone (meth) acrylamide, acetoacetoxyethyl (meth) acrylate, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) Monomers: Allyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (Meth) acrylate, 1,4-butanediol di (meth) acrylate, glycerin di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylol Propane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (Meth) acrylate, neopentyl glycol diacrylate, 1,6-hexanediol di (meth) acrylate, glycerol allyloxy di (meth) acrylate, 1,1,1-tris (hydroxymethyl) ethanedi (meth) acrylate, 1 , 1,1-tris (hydroxymethyl) ethanetri (meth) acrylate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate, dia Radical polymerizable unsaturated monomer having two or more radical polymerizable unsaturated groups in one molecule such as luisophthalate, pentaerythritol diallyl ether, divinylbenzene, methylene bis (meth) acrylamide, ethylene bis (meth) acrylamide, etc. Mention may be made as well as combinations thereof.

  In the present specification, “(meth) acrylate” means acrylate or methacrylate, and “(meth) acrylic acid” means acrylic acid or methacrylic acid. “(Meth) acryloyl” means acryloyl or methacryloyl, and “(meth) acrylamide” means acrylamide or methacrylamide.

  Examples of the solvent that can be used in the solution polymerization and dispersion polymerization include known organic solvents such as water, toluene, butanol, methyl isobutyl ketone, and butyl cellosolve. One kind or a combination of two or more kinds can be used. Can be used.

  As polymerization conditions in the solution polymerization, the reaction temperature is usually from room temperature to 250 ° C., and the reaction time is from 2 to 10 hours.

  Moreover, a known compound can be used for the radical polymerization initiator which can be used for manufacture of the said vinyl polymer (C1)-(C3), and the polymerization reaction of said (5), for example, dibenzoyl par Oxide, dioctanoyl peroxide, dilauroyl peroxide, distearoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxylaurate, tert-butyl peroxide Organic peroxides such as oxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide; azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile) Azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrile), 4,4′-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropionate), 2,2′- Azobis [2- (2-imidazolin-2-yl) propane] hydrochloride or sulfate, 2,2′-azobis [2-methylpropionamidine] hydrochloride, 2,2′-azobis [N- (2 -Carboxyethyl) -2-methylpropionamidine], 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (1-imino-1- Pyrrolidino-2-methylpropane) hydrochloride or sulfate, azo compounds such as 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; Persulfates such as um, ammonium persulfate and sodium persulfate, inorganic peroxides such as hydrogen peroxide, benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and combinations thereof Is mentioned. Furthermore, the peroxide-based polymerization initiator may be organic acids such as ascorbic acid, erythorbic acid, tartaric acid, citric acid, salts of these organic acids, tertiary amines, sugars, mercaptans, pyro-submers, if desired. Phosphate, phosphite, sodium thiosulfate, sodium sulfite, potassium sulfite, sodium hydrogen sulfite, potassium hydrogen sulfite, sodium bisulfite, sodium metabisulfite, etc., sodium formaldehyde sulfoxylate, ferrous sulfate, chloride One or more known reducing agents such as ferrous iron, longgarit, and thiourea dioxide may be added and used as a redox initiator.

  The radical polymerization initiator is about 0.001 to about 1 based on the total mass of unsaturated monomers used in the production of the vinyl polymers (C1) to (C3) and the polymerization reaction of (5). It can be used within a range of 20% by weight, preferably about 0.01 to about 10% by weight. The method for adding the radical polymerization initiator is not particularly limited, and can be appropriately selected according to the type, mass, etc., for example, it may be added in advance to an unsaturated monomer mixture or a solvent, You may add or dripping at the time of superposition | polymerization.

  The weight average molecular weight of the vinyl polymer (A) is 2,000 to 200,000, preferably 4,000 to 150,000, from the viewpoint of the stability of the emulsion of the composite vinyl polymer (B) described later. More preferably, it is in the range of 5,000 to 100,000.

  The acid value of the vinyl polymer (A) is 600 to 10 mgKOH / g, preferably 300 to 20 mgKOH / g, more preferably 250 to 40 mgKOH, from the viewpoint of the stability of the emulsion of the composite vinyl polymer (B). / G.

  Moreover, the radical reactive unsaturated group which a vinyl type polymer (A) has is set to 0. 0 on the basis of the mass of a vinyl type polymer (A) from a viewpoint of stability of the emulsion of a composite vinyl type polymer (B). It is preferably in the range of 01 to 1.5 mol / Kg, more preferably 0.1 to 1 mol / Kg.

Emulsion of composite vinyl polymer (B) The emulsion of composite vinyl polymer (B) is a vinyl polymer having a carboxyl group and a radical reactive unsaturated group, which may be partially or completely neutralized. The unsaturated monomer (b) can be obtained by emulsion polymerization in the presence of an aqueous solution or dispersion of (A). In the present specification, an aqueous dispersion of a polymer obtained by emulsion polymerization may be referred to as an emulsion.

  As a specific emulsion polymerization method for obtaining an emulsion of the composite vinyl polymer (B), for example, the vinyl polymer (A) is dissolved or dispersed in water in a polymerization reaction tank and unsaturated. A method in which a mixture of a monomer (b) and a radical polymerization initiator is added to the above polymerization reaction vessel at once to conduct a polymerization reaction; a vinyl polymer (A) and an unsaturated monomer (b) And a radical polymerization initiator are mixed and added to a polymerization reaction tank containing water continuously or intermittently for a predetermined time to carry out a polymerization reaction; a vinyl polymer in the polymerization reaction tank A part of (A) is dissolved or dispersed in water, and a mixture of the unsaturated monomer (b), the radical polymerization initiator, and the remainder of the vinyl polymer (A) is added to the polymerization reaction tank. Polymerization reaction is performed by adding all at once, or polymerization reaction is performed continuously or intermittently at a predetermined time. Method and the like to do can be mentioned.

  In the said polymerization reaction, after polymerizing in a polymerization reaction tank using a vinyl polymer (A) and a part of unsaturated monomer (b), and obtaining seed particles, You may obtain the emulsion of a composite vinyl type polymer (B) by superposing | polymerizing the remaining unsaturated monomer (b) in presence.

  The emulsion polymerization reaction of the unsaturated monomer (b) in the presence of an aqueous solution or dispersion of the vinyl polymer (A) may be carried out in several stages and can be used as the unsaturated monomer (b). As long as it is an unsaturated monomer, a mixture of unsaturated monomers having different compositions in each stage may be used.

  The production of the composite vinyl polymer (B) emulsion in the present invention is not limited to the above method, and any method can be used as long as it is emulsion polymerization.

  The composite vinyl polymer (B) is obtained as an emulsion in which the polymer particles are dispersed in water. The polymer particles may be those in which the inside of the particles is crosslinked. Such a composite vinyl polymer (B) in which the inside of the particle is crosslinked includes, for example, an unsaturated monomer having two or more radically polymerizable unsaturated groups in one molecule (hereinafter referred to as “polyvinyl monomer”). And / or a mixture of unsaturated monomers containing an unsaturated monomer having a functional group other than an unsaturated group capable of reacting in a complementary manner to form a chemical bond. It can be obtained by using as a monomer (b).

  The said polyvinyl monomer can be used in 0.01-10 mass% on the basis of the mass of an unsaturated monomer (b), Preferably it can use in the range of 0.05-5 mass%.

  Examples of the unsaturated monomer having a functional group other than the unsaturated group capable of reacting in a complementary manner to form a chemical bond include N-alkoxymethyl (meth) acrylamide and γ- (meth) acryloyloxy. Those in which functional groups of the same kind such as propyltrimethoxysilane react with each other in a complementary manner to form a chemical bond, or a combination of glycidyl group and carboxylic acid in a combination of (meth) acrylic acid glycidyl ester and (meth) acrylic acid Examples of the reaction include those in which two different functional groups react complementary to form a chemical bond such as an ester bond.

  The glass transition temperature (Tg) of the (co) polymer obtained from the unsaturated monomer (b) which is a mixture of one or more unsaturated monomers is −50 to 90 ° C., preferably −35 to 60. ° C, more preferably in the range of -25 to 40 ° C.

Here, the glass transition temperature (Tg) can be calculated by the following equation.
1 / Tg (° K) = (W1 / T1) + (W2 / T2) +.
Tg (° C.) = Tg (° K) -273
In the formula, W1, W2,... Represent the mass% of each monomer used for copolymerization, and T1, T2,... Represent the Tg (° K) of the monomer homopolymer, respectively. T1, T2,... Are values according to Polymer Hand Book (Second Edition, edited by J. Brandup, E. H. Immergut). The glass transition temperature of a homopolymer based on a monomer not described in this handbook is an actual measurement value for a homopolymer having a weight average molecular weight of about 20,000 to 50,000. This measured value is obtained by vacuum suction of a sample taken in a measuring cup to remove volatile components such as a solvent, and then using a differential scanning thermal analysis “DSC-50Q type” (trade name, manufactured by Shimadzu Corporation), The change in the amount of heat in the range of −50 ° C. to + 150 ° C. is measured at a temperature increase rate of 3 ° C./min, and the first baseline change point on the low temperature side is used.

  Moreover, the glass transition temperature (Tg) in the case of forming the emulsion which the inside of particle | grains bridge | crosslinked using the unsaturated monomer (b) containing the unsaturated monomer which has 2 or more unsaturated groups in 1 molecule. Is based on a composition in which an unsaturated monomer having two or more unsaturated groups in one molecule is excluded from the unsaturated monomer (b) which is a mixture of the unsaturated monomers. It is the value calculated using.

  The radical polymerization initiator that can be used for the production of the emulsion of the unsaturated monomer (b) and the composite vinyl polymer (B) is the vinyl polymer (A) in the previous section. The thing similar to the compound quoted as the unsaturated monomer or radical polymerization initiator which can be used in order to manufacture a unification | combination (A) can be used.

  The solid content mass of the vinyl polymer (A) is 5 to 80 mass%, preferably 10 to 70 mass%, more preferably 20 to 50 mass%, based on the solid content mass of the composite vinyl polymer (B). %. If the solid content mass of the vinyl polymer (A) is less than 5% by mass, the production stability and storage stability of the food contact coating composition of the present invention may be inferior. Moreover, when more than 80 mass%, it may be inferior to the retort whitening resistance of the coating film obtained from the coating composition for food contact of this invention.

  The resin acid value of the composite vinyl polymer (B) is 0.5 to 150 mgKOH / g, preferably 20 to 120 mgKOH / g, more preferably from the viewpoint of storage stability of the food contact coating composition of the present invention. Is in the range of 40-100 mg KOH / g. When the acid value is larger than 150 mgKOH / g, the water resistance of the obtained coating film may be lowered.

  The radical polymerization initiator is used in an amount of about 0.01 to about 5% by mass, preferably about 0.1 to about 1% by mass, based on the total mass of the unsaturated monomers (b). it can. The method for adding the radical polymerization initiator is not particularly limited and can be appropriately selected according to the type, mass, etc., for example, it may be added in advance to the unsaturated monomer mixture or water, You may add or dripping at the time of superposition | polymerization.

  In the production of the emulsion of the composite vinyl polymer (B), a known surfactant may be used together with the vinyl polymer (A) as necessary.

  Conventionally known as the above surfactants are anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants having both anionic and cationic properties, and the like. These compounds can be used. Specific examples of the surfactant include, for example, anionic surfactants such as sodium salts and ammonium salts of acids such as alkylsulfonic acid, alkylbenzenesulfonic acid, and alkylphosphoric acid, polyoxyethylene oleyl ether, polyoxyethylene stearyl Ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, poly Nonyl such as oxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate Emissions surfactant, dimethyl alkyl betaines, dimethyl alkyl lauryl betaines, mention may be made of zwitterionic surfactants such as alkyl glycine.

  Also, a polyoxyalkylene group-containing anionic surfactant having an anionic group in one molecule and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group, and radical polymerization with an anionic group in one molecule A reactive anionic surfactant having a polymerizable unsaturated group can also be used. Examples of the reactive anionic surfactant include sodium salts and ammonium salts of sulfonic acid compounds having a radical reactive unsaturated group such as an allyl group, a (meth) acryloyl group, a propenyl group, and a butenyl group.

  The surfactant is preferable in terms of retort whitening resistance of a coating film in which 5% by mass or less and further 3% by mass or less are obtained based on the total mass of the unsaturated monomer (b).

  The composite vinyl polymer (B) is obtained as an emulsion in which the polymer particles are dispersed in water. The average particle size of the particles is about 30 to 600 nm, and more preferably about 70 to 400 nm. It is preferable from the viewpoint of the storage stability of the coating composition. The average particle size was determined by diluting the sample with deionized water to a concentration suitable for measurement using a submicron particle analyzer N4 (trade name, manufactured by Beckman Coulter, Inc., particle size distribution measuring device). (Measured at about 20 ° C.)

  In the polymerization reaction for obtaining an emulsion of the composite vinyl polymer (B), the above components such as water, vinyl polymer (A), unsaturated monomer (b), radical polymerization initiator, surfactant and the like. In addition, an organic solvent, a polymer compound, a chain transfer agent, an amine compound, an alkaline metal compound, or the like may be used as desired.

Aqueous polymer (D)
The food contact coating composition of the present invention may further contain a water-soluble or water-dispersible aqueous polymer (D). As the aqueous polymer (D), a known resin which is water-soluble or water-dispersible and does not use bisphenol A as a raw material can be used. For example, acrylic resin, acrylic resin-modified polyester resin, polyester resin , Urethane resins, olefin resins, polyoxyalkylene resins, and resins obtained by modifying each of the above resins by a known method can be used alone or in combination. In the food contact coating composition of the present invention, the aqueous polymer (D) is 0 to 20% by mass, preferably 1 to 15% by mass, based on the solid content of the composite vinyl polymer (B). More preferably, it can be used within the range of 2 to 10% by mass. By including the aqueous polymer (D) in the coating composition for food contact according to the present invention, adjustments such as improving the water resistance, corrosion resistance, workability, and the like of the obtained coating film are possible.

  The weight average molecular weight of the aqueous polymer (D) is 3000 to 200000, preferably 5000 to 150,000, and more preferably 8000 from the viewpoint of the storage stability of the coating composition for food contact of the present invention and the corrosion resistance of the resulting coating film. Those within the range of ˜120,000 can be used.

  In the present specification, the weight average molecular weight or number average molecular weight is a value obtained by converting the weight average molecular weight measured with a gel permeation chromatograph (“HLC8120GPC” manufactured by Tosoh Corporation) based on the weight average molecular weight of polystyrene. is there. The columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade name). These were carried out under the conditions of mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 ml / min, detector: RI.

  The glass transition temperature of the aqueous polymer (D) is −20 ° C. or higher, preferably −10 to 130 ° C., more preferably 0 to 80 ° C. from the viewpoint of the processability of the resulting coating film. Can be used. In this specification, the glass transition temperature is determined by taking a sample into a measuring cup using a differential scanning thermal analysis “DSC-50Q type” (trade name, manufactured by Shimadzu Corporation) and removing the solvent by vacuum suction. The calorie change is measured in the range of −60 ° C. to + 150 ° C. at a rate of temperature increase of 3 ° C./min, and the first baseline change point on the low temperature side is used.

  From the viewpoint of the storage stability of the food contact coating composition of the present invention, the aqueous polymer (D) is preferably a carboxyl group-containing resin. The acid value of the aqueous polymer (D) is 20 to 250 mgKOH / g / g, preferably 50 to 200 mgKOH / g / g, more preferably 80 to 150 mgKOH / g / g, from the viewpoint of water resistance of the resulting coating film. Within range. Some or all of the carboxyl groups of the aqueous polymer (D) may be previously neutralized with a base compound such as an amine before blending the paint, or other paint components containing a base compound such as an amine when blended with the paint. You may neutralize by mixing with.

  When the aqueous polymer (D) is a vinyl polymer (D1), the vinyl polymer (D1) is a resin having substantially no cross-linked structure, and examples thereof include solution polymerization, dispersion polymerization, emulsion polymerization, It can be produced by conventionally known radical polymerization such as bulk polymerization. The unsaturated monomer that can be used for the production of the vinyl polymer (D1) is appropriately selected from those exemplified as the unsaturated monomer that can be used for the production of the vinyl polymer (A). An unsaturated monomer can be selected and used. The radical polymerization initiator that can be used for the production of the vinyl polymer (D1) is appropriately selected from those exemplified as the radical polymerization initiator that can be used for the production of the vinyl polymer (A). Can be used. When the vinyl polymer (D1) is produced by emulsion polymerization, the polymer obtained by emulsion polymerization without using the vinyl polymer (A) having a carboxyl group and a radical reactive unsaturated group. It is.

  Examples of the solvent that can be used in the solution polymerization, dispersion polymerization, and emulsion polymerization include known organic solvents such as water, toluene, butanol, methyl isobutyl ketone, and butyl cellosolve. Can be used in combination.

  As polymerization conditions in the solution polymerization, the reaction temperature is usually from room temperature to 200 ° C., and the reaction time is from 2 to 10 hours.

  The aqueous polymer (D) preferably has crosslinking reactivity from the viewpoint of water resistance of the resulting coating film. The aqueous polymer (D) is a cross-linking reaction between the aqueous polymers (D), a cross-linking reaction between the aqueous polymer (D) and the composite vinyl polymer (B), an aqueous polymer (D) and a resol type described later. You may have crosslinking reactivity in any crosslinking reaction, such as a crosslinking reaction with a phenol resin (E1) and / or an amino resin (E2). When the aqueous polymer (D) is an acrylic resin, the acrylic resin having crosslinking reactivity may be, for example, N-alkoxymethyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, hydroxyethyl (meth) acrylate, It can be obtained by copolymerizing a radical polymerizable unsaturated monomer having a crosslinkable functional group such as hydroxyethyl (meth) acrylate and another radical polymerizable unsaturated monomer.

Resol type phenol resin (E1), amino resin (E2)
The food contact coating composition of the present invention may further contain a resol type phenol resin (E1) and / or an amino resin (E2) as a curing agent. The food contact coating composition of the present invention can improve the water resistance, corrosion resistance, processability, etc. of the resulting coating film by including the resol type phenol resin (E1) and / or amino resin (E2). It is.

  Examples of the resol-type phenol resin (E1) include a phenol resin obtained by condensing a phenol compound such as phenol or cresol and formaldehyde in the presence of a reaction catalyst to introduce a methylol group; and the methylol introduced above. Those in which a part of the group is alkyl etherified with an alcohol having 1 to 6 carbon atoms are included.

  Examples of the phenol compound include bifunctional phenol compounds such as o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, and 2,5-xylenol; coalic acid, m-cresol, Phenol compounds such as trifunctional phenol compounds such as m-ethylphenol, 3,5-xylenol and m-methoxyphenol; can be used alone or in combination of two or more.

  Examples of the formaldehydes include formaldehyde, paraformaldehyde, and trioxane, which can be used alone or in combination of two or more. As the alcohol used for alkyl etherifying a part of the methylol group of the methylolated phenol resin, a monohydric alcohol having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, can be suitably used. . Suitable monohydric alcohols include methanol, ethanol, n-propanol, n-butanol, isobutanol and the like.

  The resol type phenol resin (E1) has a number average molecular weight (see Note 1) in the range of 200 to 2000, preferably 300 to 1200, and an average number of methylol groups per nucleus of the benzene nucleus of 0.3 to 2000. It is appropriate that the number is in the range of 3.0, preferably 0.5 to 3.0. In particular, among the resol-type phenol resins, a good corrosion-resistant coating film can be obtained even in a portion where the carboxylic acid formaldehyde resin obtained by condensation reaction of carboxylic acid and formaldehyde has undergone impact processing.

  As amino resin (E2), methylolation obtained by reaction of amino components such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and aldehyde components such as formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde An amino resin is mentioned. Those obtained by etherifying the methylol group of this methylolated amino resin with a lower alcohol having 1 to 6 carbon atoms are also included in the amino resin.

  The amino resin is preferably a lower alkyl etherified melamine resin or a lower alkyl etherified benzoguanamine resin obtained by etherifying some or all of the methylol groups of a methylolated melamine resin or a methylolated benzoguanamine resin with a lower alcohol. The lower alcohol used for the etherification is preferably methyl alcohol, ethyl alcohol, isobutyl alcohol, or n-butyl alcohol. These alcohols can be used for etherification alone or in combination of two or more.

  Specific examples of the melamine resin include, for example, Uban 20SE, 225 [above, both are manufactured by Mitsui Toatsu Co., Ltd.], Super Becamine J820-60, L-117-60, L-109-65, Butyl etherified melamine resins such as 47-508-60, L-118-60, G821-60 [all are manufactured by Dainippon Ink and Chemicals, Inc.]; Cymel 300, 303, 325, 327, 350, 730, 736, 738 [all manufactured by Mitsui Cytec Co., Ltd.], Melan 522, 523 [all manufactured by Hitachi Chemical Co., Ltd.], Nicarak MS001, MX430, MX650 [three Sumitomo M-55, M-100, M-40S (Sumitomo Chemical Co., Ltd.), Resimin 740, 747 (both Mon) Methyl etherified melamine resin, etc .; Cymel 232, 266, XV-514, 1130 [all manufactured by Mitsui Cytec Co., Ltd.], Nicalak MX500, MX600, MS95 [all Sanwa Chemical Resinmin 753, 755 [all manufactured by Monsanto Co., Ltd.], Sumimar M-66B (manufactured by Sumitomo Chemical Co., Ltd.), etc., and mixed etherified melamine resins of methyl ether and butyl ether, etc. .

  Specific examples of the benzoguanamine resin include Cymel 1123 (mixed etherified benzoguanamine resin of methyl ether and ethyl ether) and Cymel 1123-10 (mixed etherified benzoguanamine resin of methyl ether and butyl ether) manufactured by Mitsui Cytec Co., Ltd. ), Cymel 1128 (butyl etherified benzoguanamine resin), Mycoat 102 (methyl etherified benzoguanamine resin), and the like.

Food contact paint composition
The coating composition for food contact of the present invention contains a composite vinyl polymer (B), and further contains an aqueous polymer (D), a resol type phenol resin (E1), an amino resin (E2), etc. as desired. May be included.

  The aqueous polymer (D) is 0 to 20% by mass, preferably 2 to 15% by mass, more preferably 3 to 10% by mass, based on the solid content mass of the composite vinyl polymer (B). Can be used. When the usage-amount of an aqueous polymer (D) is more than 20 mass%, the retort whitening resistance of the coating film obtained may fall. The resol type phenol resin (E1) and amino resin (E2) have a total mass of (E1) and (E2) of 0 to 20% by mass, preferably based on the solid content mass of the composite vinyl polymer (B). Can be used in the range of 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. When the total use amount of the resol type phenol resin (E1) and the amino resin (E2) is more than 20% by mass, the water resistance and workability of the obtained coating film may be inferior.

  The food-contact coating composition of the present invention comprises an aqueous polymer as needed after further neutralizing part or all of the carboxyl groups in the composite vinyl polymer (B) with a basic compound as necessary. You may add raw materials, such as (D), a resol type phenol resin (E1), and an amino resin (E2). Moreover, when an aqueous polymer (D) has acid groups, such as a carboxyl group and a sulfonic acid group, you may use, after neutralizing a part or all of an acid group with a basic compound.

  As the basic compound that can be used for neutralizing the carboxyl group, any of ordinary inorganic bases and organic bases can be used. Examples of the inorganic base include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. Examples of the organic base include alkylamines such as ammonia, trimethylamine, triethylamine and butylamine: alcohol amines such as dimethylaminoethanol, diethanolamine and aminomethylpropanol; polyvalent amines such as ethylenediamine and diethylenetriamine; morpholine and the like. Can be mentioned. As the basic compound, ammonia and volatile amines are preferable from the viewpoint of the water resistance of the resulting coating film.

  The food contact coating composition of the present invention may be used by appropriately mixing conventionally known raw materials such as organic solvents, antifoaming agents, surfactants, lubricants, waxes, pigments and the like as necessary. it can.

  Examples of the organic solvent that can be used in the present invention include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol, amyl alcohol, n-hexanol, octanol, Alkyl alcohols such as 2-ethylhexyl alcohol; glycol ethers such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, hexyl cellosolve, methyl carbitol, ethyl carbitol, butyl carbitol; or methyl cellosolve acetate, ethyl cellosolve acetate Glycol ether esters such as dioxane, dimethylformamide, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl Ketone, etc. can be mentioned diacetone alcohol, which may be used in combination of two or more.

  Examples of the antifoaming agent include acrylic, vinyl ether, dimethylpolysiloxane, and the like, and two or more of these can be used in combination.

  The food contact coating composition of the present invention can be applied to various substrates, for example, untreated or surface-treated metal plates such as aluminum plates, steel plates, tin plates, etc. And metal plates coated with a vinyl-based primer, and those obtained by processing these metal plates into cans.

  The form of the can to which the coating composition for food contact of the present invention is applied is a two-piece can composed of two parts, a body part integrated with a cover part and a bottom part, or a cover part, a bottom part, and a body part. A three-piece can, a bottle can, etc. which consist of three parts can be mentioned, and the food contact paint composition of the present invention can be applied to each of the above parts. The film obtained from the coating composition for food contact according to the present invention is excellent in processability and corrosion resistance, and is therefore suitable for coating a lid portion that repeatedly receives irregularities in the production process of beverage cans and the like.

  Moreover, you may use the coating composition for food contact of this invention for the repair coating of the seam part (joint part) of a can inner surface, and the outer surface of cans, such as the outer surface of a can lid, and a tab.

  Various known methods such as roll coater coating, spray coating, dip coating and electrodeposition coating can be applied as a method for coating the food contact coating composition of the present invention on the substrate. Of these, roll coater coating or spray coating is preferred. The coating thickness may be appropriately selected depending on the intended use, but is usually preferably about 3 to 20 μm in terms of dry film thickness. As the drying conditions of the coated film, it is usually within the range of 10 seconds to 30 minutes, preferably at 200 to 280 ° C. for 15 seconds to 10 minutes under the condition that the maximum material arrival temperature is 120 to 300 ° C. Good.

Next, an Example is given and this invention is demonstrated more concretely. Here, “parts” and “%” mean “parts by mass” and “% by mass”, respectively.
Production of vinyl polymer (A)
(Production Example 1)
80 parts of methyl isobutyl ketone under a nitrogen gas stream in a reaction vessel equipped with a stirrer, a thermometer, a thermostat, a reflux condenser, a reflux liquid distillation device, a gas introduction pipe and a dropping device. Was heated to 90 ° C. While stirring, a mixture of 27 parts of methacrylic acid, 25 parts of styrene, 43 parts of ethyl acrylate, 5 parts of N-butoxymethylacrylamide, 1 part of t-butyl-peroxy-2-ethylhexanoate and 43 parts of methyl isobutyl ketone was stirred. I added it little by little. Thereafter, a mixture of 0.1 part of t-butyl-peroxy-2-ethylhexanoate and 32 parts of methyl isobutyl ketone was added little by little. Further, aging was carried out at about 120 ° C. until t-butyl-peroxy-2-ethylhexanoate sufficiently disappeared, and then the temperature was lowered to 110 ° C. and 0.04 part of p-methoxyphenol was added. Thereafter, while introducing nitrogen and blowing air, 4 parts of glycidyl methacrylate and 0.1 part of tetrabutylammonium bromide were added, and stirring was continued until the reaction rate of the glycidyl group of the added glycidyl methacrylate reached about 97%. . Thereafter, the mixture was cooled to 30 ° C., 20 parts of dimethylethanolamine and 120 parts of acetone were added, and 660 parts of deionized water was further added, followed by water dispersion. Thereafter, the mixture was concentrated under reduced pressure while warming to obtain about 530 g (solid content: about 20%) of an aqueous dispersion of vinyl polymer (A-1). The acid value of the vinyl polymer (A-1) was about 150 mgKOH / g, the amount of radical reactive unsaturated groups was about 0.3 mol / Kg, and the weight average molecular weight was about 80,000.

(Production Example 2)
80 parts of methyl isobutyl ketone under a nitrogen gas stream in a reaction vessel equipped with a stirrer, a thermometer, a thermostat, a reflux condenser, a reflux liquid distillation device, a gas introduction pipe and a dropping device. Was heated to 95 ° C. To this, a mixture of 40 parts of methacrylic acid, 8 parts of styrene, 52 parts of ethyl acrylate, 6 parts of t-butyl-peroxy-2-ethylhexanoate and 43 parts of methyl isobutyl ketone was added little by little with stirring. Thereafter, a mixture of 0.1 part of t-butyl-peroxy-2-ethylhexanoate and 32 parts of methyl isobutyl ketone was added little by little. Further, aging was carried out at about 120 ° C. until t-butyl-peroxy-2-ethylhexanoate sufficiently disappeared, and then the temperature was lowered to 110 ° C. and 0.04 part of p-methoxyphenol was added. Thereafter, while introducing nitrogen and blowing air, 12 parts of glycidyl methacrylate and 0.1 part of tetrabutylammonium bromide were added, and stirring was continued until the reaction rate of the glycidyl group of the added glycidyl methacrylate reached about 97%. It was. Thereafter, the mixture was cooled to 30 ° C., 27 parts of dimethylethanolamine and 120 parts of acetone were added, and 660 parts of deionized water was further added, followed by water dispersion. Then, it decompressed and concentrated while heating, and obtained about 540 g (solid content about 20%) of the aqueous dispersion of a vinyl polymer (A-2). The acid value of the vinyl polymer (A-2) was about 190 mgKOH / g, the amount of radical reactive unsaturated groups was about 0.8 mol / Kg, and the weight average molecular weight was about 20,000.

(Production Example 3)
80 parts of methyl isobutyl ketone under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device Was heated to 95 ° C. 30 parts of acrylic acid, 30 parts of styrene, 33 parts of ethyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 2 parts of N-butoxymethyl acrylamide, 6 parts of t-butyl-peroxy-2-ethylhexanoate and methyl isobutyl ketone 43 parts of the mixture were added in portions with stirring. Thereafter, a mixture of 0.1 part of t-butyl-peroxy-2-ethylhexanoate and 32 parts of methyl isobutyl ketone was added little by little. Further, after aging until t-butyl-peroxy-2-ethylhexanoate disappeared sufficiently at about 120 ° C., the temperature was lowered to 80 ° C. and 0.04 part of p-methoxyphenol was added. Thereafter, nitrogen introduction was stopped and air was blown in, while adding 6.3 parts of isophorone diisocyanate and 3.7 parts of 2-hydroxyethyl methacrylate and 0.06 part of tetraisopropoxytitanium were added. The reaction was continued until the reaction rate of the group reached about 99%. Thereafter, the mixture was cooled to 30 ° C., 30 parts of dimethylethanolamine and 120 parts of acetone were added, and 660 parts of deionized water was further added and dispersed in water. Thereafter, the mixture was concentrated under reduced pressure while heating, and filtered to obtain about 540 g (about 20% solid content) of an aqueous dispersion of vinyl polymer (A-3). The acid value of the vinyl polymer (A-3) was about 210 mgKOH / g, the amount of radical reactive unsaturated groups was about 0.3 mol / Kg, and the weight average molecular weight was about 40,000.

(Production Example 4)
80 parts of methyl isobutyl ketone under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device Was heated to 95 ° C. While stirring a mixture of 35 parts of methacrylic acid, 25 parts of styrene, 31 parts of ethyl acrylate, 9 parts of 2-hydroxyethyl acrylate, 6 parts of t-butyl-peroxy-2-ethylhexanoate and 43 parts of methyl isobutyl ketone. I added it little by little. Thereafter, a mixture of 0.1 part of t-butyl-peroxy-2-ethylhexanoate and 32 parts of methyl isobutyl ketone was added little by little. Further, aging was carried out at about 120 ° C. until t-butyl-peroxy-2-ethylhexanoate sufficiently disappeared, and then the temperature was lowered to 80 ° C. and 0.04 part of p-methoxyphenol was added. Thereafter, the mixture obtained by reacting 5 parts of isophorone diisocyanate and 3 parts of 2-hydroxyethyl methacrylate in advance while blowing off nitrogen and blowing in air, 1 part of isophorone diisocyanate, 1 part of 2-hydroxyethyl methacrylate and tetraisopropoxy Titanium 0.06 part was added and reacted until the reaction rate of isocyanate groups reached about 99%. Thereafter, the mixture was cooled to 30 ° C., 29 parts of dimethylethanolamine and 120 parts of acetone were added, and 660 parts of deionized water was further added, followed by water dispersion. Thereafter, the mixture was concentrated under reduced pressure while heating, and filtered to obtain about 540 g (about 20% solid content) of an aqueous dispersion of vinyl polymer (A-4). The acid value of the vinyl polymer (A-4) was about 210 mgKOH / g, the amount of radical reactive unsaturated groups was about 0.3 mol / Kg, and the weight average molecular weight was about 40,000.

Production of vinyl polymer (X) having no radical reactive unsaturated group (Production Example 5)
80 parts of methyl isobutyl ketone under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device Was heated to 95 ° C. 30 parts of acrylic acid, 30 parts of styrene, 33 parts of ethyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 2 parts of N-butoxymethyl acrylamide, 6 parts of t-butyl-peroxy-2-ethylhexanoate and methyl isobutyl ketone 43 parts of the mixture were added in portions with stirring. Thereafter, a mixture of 0.1 part of t-butyl-peroxy-2-ethylhexanoate and 32 parts of methyl isobutyl ketone was added little by little. Further, aging was carried out at about 120 ° C. until t-butyl-peroxy-2-ethylhexanoate disappeared sufficiently. Thereafter, the mixture was cooled to 30 ° C., 30 parts of dimethylethanolamine and 120 parts of acetone were added, and 660 parts of deionized water was further added and dispersed in water. Thereafter, the mixture was concentrated under reduced pressure while heating, and filtered to obtain about 540 g of an aqueous dispersion of a vinyl polymer (X-1) having no radical reactive unsaturated group (solid content of about 20%). It was. The acid value of the vinyl polymer (X-1) was about 230 mgKOH / g, the amount of radical reactive unsaturated groups was 0 mol / Kg, and the weight average molecular weight was about 20,000.

Production of composite vinyl polymer (B) (Production Example 6)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. An aqueous dispersion 75 parts (solid content: about 20%) of the obtained vinyl polymer (A-1) was charged and heated to 80 ° C. To this, 240 parts of deionized water, 75 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-1) ( A mixture of 22 parts of styrene, 47 parts of ethyl acrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-1) (solid content was about 20%). The acid value of the composite vinyl polymer (B-1) was about 50 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-1) is about 0 ° C.

(Production Example 7)
Obtained in Production Example 2 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. 100 parts of an aqueous dispersion of the vinyl polymer (A-2) obtained (solid content: about 20%) was charged and heated to 80 ° C. To this, 200 parts of deionized water, 100 parts of an aqueous dispersion of the vinyl polymer (A-2) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-2) ( A mixture of 19 parts of styrene, 40 parts of ethyl acrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-2) (solid content was about 20%). The acid value of the composite vinyl polymer (B-2) was about 80 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-2) is about 0 ° C.

(Production Example 8)
Obtained in Production Example 3 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device. 75 parts of an aqueous dispersion of the vinyl polymer (A-3) obtained (solid content: about 20%) was charged and heated to 80 ° C. To this, 240 parts of deionized water, 75 parts of an aqueous dispersion of the vinyl polymer (A-3) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-3) ( A mixture of 22 parts of styrene, 47 parts of ethyl acrylate and 1 part of glycerin dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an aqueous dispersion of the composite vinyl polymer (B-3) (the solid content was about 20%). ). The acid value of the composite vinyl polymer (B-3) was about 60 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-3) is about 0 ° C.

(Production Example 9)
Obtained in Production Example 4 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device. 125 parts of an aqueous dispersion (solid content: about 20%) of the vinyl polymer (A-4) thus obtained was charged and heated to 80 ° C. To this, 160 parts of deionized water, 125 parts of an aqueous dispersion of vinyl polymer (A-4) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-4) ( A mixture of 16 parts of styrene, 33 parts of ethyl acrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-4) (solid content was about 20%). The acid value of the composite vinyl polymer (B-4) was about 100 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-4) is about 0 ° C.

(Production Example 10)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. An aqueous dispersion 75 parts (solid content: about 20%) of the obtained vinyl polymer (A-1) was charged and heated to 80 ° C. To this, 240 parts of deionized water, 75 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-5) ( A mixture of 20 parts ethyl acrylate, 5 parts butyl acrylate, 5 parts butyl methacrylate, 39 parts 2-ethylhexyl acrylate and 1 part ethylene glycol dimethacrylate) and 0.25 parts ammonium persulfate was added dropwise with stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-5) (solid content was about 20%). The acid value of the composite vinyl polymer (B-5) was about 50 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-5) is about −40 ° C.

(Production Example 11)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. An aqueous dispersion 75 parts (solid content: about 20%) of the obtained vinyl polymer (A-1) was charged and heated to 80 ° C. To this, 240 parts of deionized water, 75 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-6) ( A mixture of 35 parts of styrene, 25 parts of methyl methacrylate, 7 parts of butyl acrylate, 2 parts of butyl methacrylate and 1 part of glycerin dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-6) (solid content was about 20%). The acid value of the composite vinyl polymer (B-6) was about 50 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-6) is about 70 ° C.

(Production Example 12)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. 40 parts of an aqueous dispersion of the resulting vinyl polymer (A-3) (solid content of about 20%) and 288 parts of deionized water were charged and the temperature was raised to 80 ° C. Unsaturated monomer (b-7) (a mixture of 27 parts of styrene, 27 parts of ethyl acrylate, 30 parts of butyl methacrylate, 5 parts of butyl acrylate, 2 parts of methacrylic acid and 1 part of ethylene glycol dimethacrylate) and ammonium persulfate A mixture of 0.25 parts and 20 parts of deionized water was added dropwise with stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-7) (solid content was about 20%). The acid value of the composite vinyl polymer (B-7) was about 30 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-7) is about 20 ° C.

(Production Example 13)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. 180 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained (solid content: about 20%) was charged and the temperature was raised to 80 ° C. To this, 72 parts of deionized water, 180 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (b-8) ( A mixture of 9 parts of styrene, 9 parts of ethyl acrylate, 9 parts of butyl acrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (B-8) (solid content was about 20%). The acid value of the composite vinyl polymer (B-8) was about 110 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-8) is about -10 ° C.

(Production Example 14)
Obtained in Production Example 3 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device. 30 parts of an aqueous dispersion of the vinyl polymer (A-3) (solid content: about 20%), 0.5 part of ammonium dodecylbenzenesulfonate, and 316 parts of deionized water were charged and the temperature was raised to 80 ° C. Unsaturated monomer (b-9) (a mixture of 28 parts of styrene, 28 parts of ethyl acrylate, 30 parts of butyl methacrylate, 5 parts of butyl acrylate, 2 parts of methacrylic acid and 1 part of ethylene glycol dimethacrylate) and ammonium persulfate A mixture of 0.25 parts and 20 parts of deionized water was added dropwise with stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an aqueous dispersion of the composite vinyl polymer (B-9) (the solid content was about 20%). ). The acid value of the composite vinyl polymer (B-9) was about 25 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (b-9) is about 20 ° C.

(Production Example 15)
Obtained in Production Example 5 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. 75 parts of an aqueous dispersion of the vinyl polymer (X-1) obtained (solid content: about 20%) was charged and the temperature was raised to 80 ° C. To this, 240 parts of deionized water, 75 parts of an aqueous dispersion of vinyl polymer (X-1) (solid content of about 20%), unsaturated monomer (y-1) (22 parts of styrene, ethyl acrylate 47) A mixture of 1 part of ethylene glycol dimethacrylate and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (Y-1) (solid content was about 20%). The acid value of the composite vinyl polymer (Y-1) was about 70 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (y-1) is about 0 ° C.

(Production Example 16)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. 5 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained (solid content: about 20%) and 112 parts of deionized water were charged and heated to 80 ° C. To this, 240 parts of deionized water, 5 parts of an aqueous dispersion (solid content of about 20%) of the vinyl polymer (A-1) obtained in Production Example 1, an unsaturated monomer (y-2) ( A mixture of 30 parts of styrene, 67 parts of ethyl acrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (Y-2). 20%), a large amount of flocculation was generated, and it was found that there was a problem in terms of manufacturability. The acid value of the composite vinyl polymer (Y-2) was about 3 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (y-2) is about 0 ° C.

(Production Example 17)
Obtained in Production Example 3 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distillation device, nitrogen inlet tube and dropping device. 237 parts (solid content: about 20%) of an aqueous dispersion of the vinyl polymer (A-3) obtained were charged and heated to 80 ° C. To this, 200 parts of deionized water, 238 parts of an aqueous dispersion (about 20% solids) of the vinyl polymer (A-3) obtained in Production Example 3, an unsaturated monomer (y-3) ( A mixture of 1.7 parts of styrene and 3.3 parts of ethyl acrylate) and 0.25 part of ammonium persulfate was added dropwise little by little with stirring. Thereafter, a mixture of 20 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (Y-3) (solid content was about 20%). The acid value of the composite vinyl polymer (Y-3) was about 200 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (y-3) is about 0 ° C.

(Production Example 18)
Obtained in Production Example 1 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. An aqueous dispersion 75 parts (solid content: about 20%) of the obtained vinyl polymer (A-1) was charged and heated to 80 ° C. To this, 240 parts of deionized water, 75 parts of an aqueous dispersion of the vinyl polymer (A-1) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (y-4) ( A mixture of 47 parts of styrene, 22 parts of methyl methacrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (Y-4) (solid content was about 20%). The acid value of the composite vinyl polymer (Y-4) was about 50 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (y-4) is about 95 ° C.

(Production Example 19)
Obtained in Production Example 2 under a nitrogen gas stream in a reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, reflux liquid distilling device, nitrogen inlet pipe and dropping device. 100 parts of an aqueous dispersion of the vinyl polymer (A-2) obtained (solid content: about 20%) was charged and heated to 80 ° C. To this, 200 parts of deionized water, 100 parts of an aqueous dispersion of the vinyl polymer (A-2) obtained in Production Example 1 (solid content of about 20%), unsaturated monomer (y-5) ( A mixture of 10 parts of ethyl acrylate, 49 parts of 2-ethylhexyl acrylate and 1 part of ethylene glycol dimethacrylate) and 0.25 part of ammonium persulfate was added dropwise little by little while stirring. Thereafter, a mixture of 40 parts of deionized water and 0.05 part of ammonium persulfate was added dropwise little by little to obtain about 500 parts of an emulsion of the composite vinyl polymer (Y-5) (solid content was about 20%). The acid value of the composite vinyl polymer (Y-5) was about 80 mgKOH / g. The glass transition temperature of the copolymer obtained from the unsaturated monomer (y-5) is about -55 ° C.

  Table 1 shows vinyl polymers [(A-1) to (A-4), (X-1)] and unsaturated monomers used in the production of the composite vinyl polymers obtained in Production Examples 6 to 19. Compound [(b-1) to (b-9), (y-1) to (y-5)], acid value of the composite vinyl polymer, and (co) of the unsaturated monomer The glass transition temperature (° C.) of the polymer is shown.

Production of aqueous polymer (D) (Production Example 20)
80 parts of methyl isobutyl ketone under a nitrogen gas stream in a reaction vessel equipped with a stirrer, a thermometer, a thermostat, a reflux condenser, a reflux liquid distillation device, a gas introduction pipe and a dropping device. Was heated to 90 ° C. While stirring, a mixture of 25 parts of methacrylic acid, 25 parts of styrene, 42 parts of ethyl acrylate, 8 parts of N-butoxymethylacrylamide, 1 part of t-butyl-peroxy-2-ethylhexanoate and 43 parts of methyl isobutyl ketone was stirred. I added it little by little. Thereafter, a mixture of 0.1 part of t-butyl-peroxy-2-ethylhexanoate and 32 parts of methyl isobutyl ketone was added little by little. Further, aging was carried out at about 120 ° C. until t-butyl-peroxy-2-ethylhexanoate disappeared sufficiently. Thereafter, the mixture was cooled to 30 ° C., 21 parts of dimethylethanolamine and 120 parts of acetone were added, and 660 parts of deionized water was further added and dispersed in water. Then, it decompressed and concentrated while heating, and obtained about 530 parts (solid content about 20%) of the aqueous dispersion of vinyl polymer (D-1). The acid value of the vinyl polymer (D-1) was about 160 mgKOH / g, and the weight average molecular weight was about 80,000.

Food contact coating composition (F-1-18)
(Example 1)
500 parts (100 parts solids) of the composite vinyl polymer (B-1) emulsion having a solids content of about 20% by mass obtained in Production Example 6 and “CKS-3898” having a solids content of about 50% by mass (trade name) , Manufactured by Showa Denko KK, resol type phenol resin, normal butanol solution) 10 parts (5 parts solid content) and 60 parts butyl cellosolve with stirring with a disper, and mixed with deionized water to adjust the solid content. A coating composition F-1 for food contact of about 18% by mass was obtained.

(Examples 2 to 13, Comparative Examples 1 to 5)
In the same manner as in Example 1, the ingredients were mixed with stirring in accordance with the formulations shown in Tables 2 and 3 below, deionized water was added to adjust the solid content, and the food contact coating composition having a solid content of 20% by mass. The thing F-2-18 was created. In addition, the compounding quantity of each component in a table | surface is based on solid content. The evaluation results of the following tests are also shown in Tables 2 and 3. In addition, "Cymel 303" (trade name, methyl etherified melamine resin, manufactured by Mitsui Cytec) was used as the amino resin in the table.

Preparation of test plate Each food contact coating composition obtained in the above Examples and Comparative Examples was dried on a # 5021 aluminum plate having a thickness of 0.25 mm and subjected to a phosphate chromate treatment so that the dry coating thickness was 5 μm. The test plate was coated with a bar coater and baked and cured at 200 ° C. for 1 minute. The performance test was performed according to the following test method.

(Storage stability)
The paint conditions after the aqueous paints of Examples and Comparative Examples were stored at 40 ° C. for 1 month were evaluated according to the following criteria.
◎: No abnormality ○: Observed with a transmission microscope with a magnification of 100 times, slight oil droplets are observed Δ: Oil droplets are visually observed x: Remarkable oil droplets are generated (T Bend folding workability)
After cutting the test coated plate into 5 cm in the rolling direction and 4 cm in the vertical direction, two aluminum plates having a thickness of 0.26 mm are placed between the bent portions of the test coated plate in which the lower part is folded in a room at 20 ° C. Insert the pin into a special goby fold type DuPont impact tester, drop a 1kg thick iron weight with a flat contact surface from a height of 50cm and give impact to the bent part to evaluate the T-bend bending workability. A test piece was prepared for the purpose. The bending tip of the test piece was energized for 6 seconds at an applied voltage of 6.5 V, the current value (mA) of the bending tip 20 mm wide was measured, and evaluated according to the following criteria. In addition, evaluation of (double-circle) (triangle | delta) is a practical range.
A: Less than 10 mA B: 10 mA or more and less than 20 mA B: 20 mA or more and less than 40 mA B: 40 mA or more and less than 80 mA X: 80 mA or more (Retort whitening resistance)
The test coating plate was immersed in water, and the whitening state of the coating film treated at 125 ° C. for 30 minutes in an autoclave was evaluated according to the following criteria. In addition, evaluation of (double-circle) (triangle | delta) is a practical range.
◎: No whitening was observed ○: Partial whitening was slightly recognized ○ △: Slight whitening was observed overall △: Quite whitening was observed ×: Whitening was remarkably observed (corrosion resistance)
The test coated plate was immersed in a mixed aqueous solution in which 3% each of citric acid, malic acid and sodium chloride were dissolved, and stored at 40 ° C. for 2 weeks, and then the coated surface state was evaluated visually according to the following criteria. In addition, evaluation of (double-circle) (triangle | delta) is a practical range.
A: Glossy, no corrosion is observed. B: Glossy, but there is no corrosion.
○ △: Corrosion is slightly observed Δ: Corrosion is considerably recognized ×: Corrosion is remarkable [Feathering resistance (film remaining resistance)]
The test coated plate was made into a lid using a lid-making press to produce a can lid having a coating surface on the inner surface side. The prepared can lid is immersed in boiling water at 100 ° C. for 10 minutes, and then the opening piece (tab) provided on the top surface of the can lid is pulled upward with the coating film surface facing downward. The part was opened. And the peeling width of the coating film from the opening edge part of the opening part was measured, and the following reference | standard evaluated. In addition, evaluation of (double-circle) (triangle | delta) is a practical range.

A: Maximum peel width of the coating film is less than 0.2 mm,
○: The maximum peel width of the coating film is 0.2 mm or more and less than 0.4 mm,
○ △: The maximum peel width of the coating film is 0.4 mm or more and less than 0.5 mm,
Δ: The maximum peel width of the coating film is 0.5 mm or more and less than 1.0 mm,
X: The maximum peeling width of the coating film is 1.0 mm or more

Claims (11)

Emulsion polymerization of unsaturated monomer (b) in the presence of an aqueous solution or dispersion of vinyl polymer (A) having a carboxyl group and radical reactive unsaturated group which may be partially or fully neutralized A coating composition for food contact, comprising an emulsion of a composite vinyl polymer (B), wherein the vinyl polymer (A) is contained in 100 parts by mass of the solid content of the composite vinyl polymer (B). The food contact coating material, wherein the solid content is in the range of 5 to 80 parts by mass and the glass transition temperature of the polymer of the unsaturated monomer (b) is in the range of -50 to 90 ° C. Composition. The vinyl polymer (A) is obtained by reacting a vinyl polymer (C1) having a carboxyl group which may be partially or completely neutralized with a compound having an epoxy group and a radical reactive unsaturated group. The food contact coating composition according to claim 1, wherein The vinyl polymer (A) is a vinyl polymer (C2) having a carboxyl group and a hydroxyl group, which may be partially or wholly neutralized, and a compound having an isocyanate group and a radical reactive unsaturated group. The food contact coating composition according to claim 1, which is obtained by reacting. The vinyl polymer (A) includes a vinyl polymer (C2) having a carboxyl group and a hydroxyl group, which may be partially or wholly neutralized, a polyisocyanate compound, a hydroxyl group and a radical reactive unsaturated group. The coating composition for food contact according to claim 1, which is obtained by reacting a mixture with a compound having the same. The water-soluble or water-dispersible aqueous polymer (D) having a weight average molecular weight in the range of 3000 to 200,000 and a glass transition temperature of -20 ° C or higher is further included. The coating composition for food contact as described in any one of Claims. The food-contact coating composition according to claim 5, wherein the aqueous polymer (D) is a vinyl polymer (D1). The coating composition for food contact according to any one of claims 1 to 6, further comprising a resol type phenol resin (E1) and / or an amino resin (E2). The food contact paint composition according to any one of claims 1 to 7, wherein the food contact paint composition is a food contact paint composition for coating the inner surface of a can. A coated can wherein the inner surface of the can is coated with the food contact paint composition according to any one of claims 1 to 8. A coated can in which the inner surface of the lid of the can is coated with the food contact paint composition according to any one of claims 1 to 8. A coated can wherein the outer surface of the lid of the can is coated with the food contact paint composition according to claim 1.