JP2008031453A - Water-based coating composition and method of coating plastic molding using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based coating composition which forms a coating film excellent in water resistance, moisture resistance, gas hole resistance, solvent resistance and scratch resistance when forming a thick film even during low-temperature baking at ≤90°C, and to provide a method of coating a plastic molding using the composition. <P>SOLUTION: The water-based coating composition comprises (A) an aqueous dispersion of a modified polyolefin prepared by dispersing an unsaturated carboxylic acid or an acid-anhydride-modified polyolefin (a) having ≤120°C melting point and 30,000-200,000 number-average molecular weight into an aqueous medium, (B) a resin having at least one functional cross-linking groups selected from a carbodiimide group, an oxazoline group and a carbonyl group, and (C) a pigment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aqueous coating composition that forms a coating film excellent in water resistance, moisture resistance, gasohol resistance, solvent resistance, scratch resistance, etc. during thick film formation even at low temperature baking of 90 ° C. or less, and this composition The present invention relates to a method of painting a plastic molded product using a product.

  In place of metal, a molded product of polyolefin containing an olefin such as ethylene or propylene is often used as a member of an automobile outer plate part, home appliance or the like. When a two-component topcoat containing a polyisocyanate compound is applied to these molded articles, a primer containing a chlorinated polyolefin is usually used beforehand in order to improve the adhesion between the topcoat film and the molded article. It is painted.

  However, since such a rubber component (for example, styrene butadiene rubber, isoprene rubber, etc.) and a hydroxyl group-containing polyolefin that have been contained in the molded polyolefin have been reduced or not added at all, such a primer can be used as a molded product. There was a defect that the adhesion of the ink was reduced.

  In order to solve the above problem, the present applicant has proposed a primer using a specific chlorinated polyolefin and a block polyisocyanate and using these together with a polyol resin (see Patent Document 1).

  In the primer as described above, aromatic organic solvents such as toluene and xylene have been used from the viewpoint of the solubility of the polyolefin used. However, from the viewpoint of safety and health and environmental conservation, There was a demand for water-based treatment.

  On the other hand, various attempts have been made to produce an aqueous dispersion of chlorinated polyolefin. For example, Patent Document 2 and Patent Document 3 have proposed such measures.

  On the other hand, the polyolefin molded body has been made highly rigid, and especially in the low temperature baking conditions of about 80 to 90 ° C., the aqueous dispersion of chlorinated polyolefin that has been used in conventional primers has sufficient adhesion of the formed coating film. It cannot be obtained, and it has become difficult to respond. Further, in automotive parts applications, it has been required to have gasohol resistance and the like, and it has become more difficult to deal with.

  On the other hand, plastic moldings made of polyolefin materials are also being used in the interior of automobiles, and these are also one-coat finishes and are not only adhesive but also solvent resistant by baking at a lower temperature than baking conditions of 80-90 ° C. In addition, there is a demand for the formation of a coating film having excellent scratch resistance.

JP 2002-121462 A JP 2003-327761 A JP 2004-91559 A

  An object of the present invention is to form an aqueous coating composition that forms a coating film excellent in water resistance, moisture resistance, gasohol resistance, solvent resistance, scratch resistance, etc. even during low-temperature baking at 90 ° C. or less, and An object of the present invention is to provide a method for coating a plastic molded article using this composition.

  As a result of intensive studies by the present inventors, it has been found that the above object can be achieved by blending an aqueous dispersion of a specific modified polyolefin, a resin having a specific crosslinkable functional group, and a pigment.

  That is, the present invention comprises (A) dispersing an unsaturated carboxylic acid or anhydride-modified polyolefin (a) having a melting point of 120 ° C. or less and a weight average molecular weight in the range of 30,000 to 200,000 in an aqueous medium. An aqueous dispersion comprising an aqueous dispersion of modified polyolefin, (B) a resin having at least one crosslinkable functional group selected from a carbodiimide group, an oxazoline group and a carbonyl group, and (C) a pigment. The present invention relates to a coating composition and a method for coating a plastic molded article using the composition.

  According to the present invention, by using a resin having a specific crosslinkable functional group in combination with an aqueous dispersion of a modified polyolefin, it has excellent adhesion to a molded product even at low temperature baking of 90 ° C. or lower, and is also water and moisture resistant. In addition, it is possible to form a coating film with excellent gasohol resistance, and furthermore, with a single coat finish, it has excellent adhesion to molded products, and also has excellent solvent resistance and scratch resistance. It is possible. Therefore, the water-based paint composition of the present invention is very useful as a primer for automobile outer plate parts and as a one-coat finish paint for interior parts.

  The modified polyolefin aqueous dispersion (A) used in the present invention is obtained by dispersing an unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) in an aqueous medium.

  The unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is usually obtained by polymerizing one or more selected from olefins having 2 to 10 carbon atoms such as ethylene, propylene, butylene, and hexene. Polyolefin is further modified by graft copolymerization according to a known method using unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, or acid anhydrides thereof. Those modified with maleic acid or its acid anhydride are preferred. The amount of graft copolymerization with the unsaturated carboxylic acid or acid anhydride thereof is 1 to 20% by weight, preferably 2 to 10% by weight, based on the solid content of the polyolefin.

  The polyolefin used in the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is a single polymerization catalyst, particularly from the viewpoint that the obtained polyolefin has a narrow molecular weight distribution and excellent random copolymerizability. Those produced using a site catalyst are preferred. The single-site catalyst has the same active site (single site), and among the single-site catalysts, a metallocene catalyst is particularly preferable, and the metallocene catalyst usually has at least one conjugated five-membered ring ligand. Metallocene (bis (cyclopentadienyl) metal complex and its derivatives) which are transition metal compounds of groups 4 to 6 and 8 of the periodic table and group 3 rare earth transition metal compounds, and aluminoxane and the like that can activate the metallocene It is obtained by combining a catalyst and an organoaluminum compound such as trimethylaluminum. As the method for producing the polyolefin, a conventionally known method can be adopted, and for example, a method in which propylene, ethylene or the like and hydrogen are supplied to the reaction vessel and the alkylaluminum and the metallocene catalyst are continuously added can be mentioned.

  The unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) may be further acrylic-modified as necessary. Examples of the polymerizable unsaturated monomer used for the acrylic modification include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and cyclohexyl (meth) acrylate. Alkyl esters of (meth) acrylic acid such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and stearyl (meth) acrylate; (meth) acrylic acid, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) Acrylic monomers such as acrylate, (meth) acrylamide, (meth) acrylonitrile, and further styrene can be used, and these can be used alone or in admixture of two or more.

  In the present specification, “(meth) acryl” means “acryl or methacryl”, and “(meth) acrylate” means “acrylate or methacrylate”.

  Examples of the acrylic modification method include, for example, reacting with a carboxyl group in an unsaturated carboxylic acid or acid anhydride-modified polyolefin, for example, by first reacting a glycidyl (meth) acrylate to form a polymerizable unsaturated group. Introducing and then copolymerizing with the unsaturated carboxylic acid or acid anhydride-modified polyolefin into which a polymerizable unsaturated group has been introduced using other monomers alone or in combination of two or more. The amount of the polymerizable unsaturated monomer used in the acrylic modification is 85% by weight or less, preferably 0.1 to 80% by weight in terms of solid content in the resulting modified polyolefin (a). It is desirable from the viewpoint of compatibility with other components and adhesion of the formed coating film.

  In addition, the unsaturated carboxylic acid or anhydride-modified polyolefin (a) may be polyoxygenated as necessary from the viewpoint of water resistance, moisture resistance, gasohol resistance, etc. when forming a thick film by low-temperature baking at 90 ° C. or lower. It may be modified with a compound having an alkylene chain. Examples of the polyoxyalkylene chain in the compound having a polyoxyalkylene chain include a polyoxyethylene chain, a polyoxypropylene chain, a block chain of polyoxyethylene and polyoxypropylene, and the like.

  The compound having a polyoxyalkylene chain has a number average molecular weight of 400 to 3,000, preferably 500 to 2,000. When the number average molecular weight is less than 400, the effect as a hydrophilic group cannot be sufficiently exhibited, and the coating performance (especially water resistance) is adversely affected. Is unfavorable because it becomes solid at room temperature and its solubility becomes poor, and is difficult to handle.

  The modification with the compound having a polyoxyalkylene chain is particularly obtained by reacting an unsaturated carboxylic acid or acid anhydride-modified polyolefin with a compound (i) having a hydroxyl group at one end and a polyoxyalkylene chain. In the case where the unsaturated carboxylic acid or acid anhydride-modified polyolefin is acrylic-modified as described above, the compound (ii) having a polymerizable unsaturated group at one end and a polyoxyalkylene chain is used. Can be suitably used.

  Examples of the compound (i) having a hydroxyl group at one end and having a polyoxyalkylene chain include polyoxyalkylene alkyl ethers such as polyoxyethylene stearyl ether; polyoxyethylene nonylphanyl ether, polyoxyethylene dodecyl phenyl ether and the like Polyoxyalkylene alkyl phenyl ethers; polyoxyalkylene glycol fatty acid esters such as polyoxyethylene fatty acid esters; polyoxyalkylene alkyl amines such as polyoxyethylene alkylamines, ethylene oxide propylene oxide polymer adducts of alkylalkanolamines, and the like These can be used alone or in combination of two or more. The reaction between the unsaturated carboxylic acid or acid anhydride modified polyolefin and the compound (i) having a hydroxyl group at one end and a polyoxyalkylene chain is carried out by reacting the unsaturated carboxylic acid or acid anhydride modified polyolefin at 80 to 200 ° C. It can be carried out by heating and melting, adding the compound (i) thereto, adding a basic substance or the like as necessary, and heating. The ratio of the compound (i) used is 0.5 to 50 parts by weight, preferably 0.5 to 25 parts by weight, based on 100 parts by weight of the solid content of the unsaturated carboxylic acid or anhydride modified polyolefin. .

  Examples of the compound (ii) having a polymerizable unsaturated group at one end and having a polyoxyalkylene chain include polyerylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyoxyethylene methyl ether (meta ) Acrylate, polyoxypropylene methyl ether (meth) acrylate, polyoxyethylene lauryl ether (meth) acrylate, polyoxyethylene nonylphenyl ether (meth) acrylate, polyoxyethylene lauryl ether maleate, allyl group-containing polyoxyethylene nonyl Examples thereof include phenyl ether, and these can be used alone or in combination of two or more. The reaction between the unsaturated carboxylic acid or acid anhydride modified polyolefin (i) and the compound (ii) having a polymerizable unsaturated group at one end and a polyoxyalkylene chain is an unsaturated carboxylic acid or acid anhydride modified. Polyolefin is heated and melted at 80 to 200 ° C., and has reactivity with a carboxyl group in the unsaturated carboxylic acid or anhydride modified polyolefin as described in the description of the acrylic modification, for example, glycidyl (meth) acrylate, (Meth) acrylic acid 2-hydroxyethyl and the like are added, if necessary, a polymerization inhibitor, a basic substance, etc. are added and heated to introduce a polymerizable unsaturated group into the modified polyolefin, and then a compound ( ii) may be added, and a polymerization initiator or the like may be added and heated as necessary. The use ratio thereof is desirably 0.5 to 50 parts by weight, preferably 0.5 to 25 parts by weight of the compound (ii) with respect to 100 parts by weight of the solid content of the unsaturated carboxylic acid or anhydride modified polyolefin. .

  The unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) may be further chlorinated as necessary. The chlorination of polyolefin can be performed, for example, by blowing chlorine gas into an organic solvent solution or dispersion of polyolefin or a modified product thereof, and the reaction temperature can be 50 to 120 ° C. The chlorine content in the chlorinated polyolefin (solid content) can be changed according to the physical properties desired for the chlorinated polyolefin. Desirably, the amount is 35% by weight or less, particularly 10 to 30% by weight, more particularly 12 to 25% by weight, based on the weight of the compound.

  The polyolefin used for the unsaturated carboxylic acid or acid anhydride modified polyolefin (a) is particularly preferably one containing propylene as a polymerization component, and the unsaturated carboxylic acid or acid anhydride modified polyolefin ( The weight fraction of propylene in a) is preferably 0.5 to 0.99, preferably 0.7 to 0.95 from the viewpoint of compatibility with other components and adhesion of the formed coating film. .

  The unsaturated carboxylic acid or anhydride-modified polyolefin (a) obtained as described above has a melting point of 120 ° C. or lower, preferably in the range of 50 to 100 ° C., and a weight average molecular weight (Mw) of 30000 to 18000, preferably Is in the range of 50,000 to 120,000. Deviating from these ranges is not preferable because the object of the present invention is not achieved, and compatibility with other components and interlaminar adhesion of the formed coating film to the polyolefin substrate and the top coating film layer are lowered. The heat of fusion of the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is preferably in the range of 1 to 50 mJ / mg, preferably 2 to 50 mJ / mg from the viewpoint of adhesion as described above.

  Here, the melting point and heat of fusion were “DSC-5200” (trade name, manufactured by Seiko Denshi Kogyo Co., Ltd.), and 20 mg of modified polyolefin was used. Obtained by measuring the amount of heat. The melting point can be adjusted by changing the composition of the polyolefin, particularly the amount of the α-olefin monomer. If it is difficult to determine the heat of fusion, the sample to be measured may be heated to 120 ° C., cooled at 10 ° C./min, and then allowed to stand for 2 days or longer to measure the amount of heat by the above method.

The weight average molecular weight of the modified polyolefin is a value obtained by converting the weight average molecular weight measured by gel permeation chromatography on the basis of the weight average molecular weight of polystyrene. “HLC / GPC150C” (Water, 60 cm × 1) ), A column temperature of 135 ° C., o-dichlorobenzene as a solvent, and a flow rate of 1.0 ml / min. An injection sample was prepared by dissolving at 140 ° C. for 1 to 3 hours so that a solution concentration of 5 mg of polyolefin was obtained in 3.4 ml of o-dichlorobenzene. An example of a column used for gel permeation chromatography is “GMH _HR- H (S) HT” (trade name, manufactured by Tosoh Corporation).

  In the present invention, the ratio (Mw / Mn) between the weight average molecular weight and the number average molecular weight of the unsaturated carboxylic acid or acid anhydride modified polyolefin (a) is 1.5 to 4.0, preferably 2.0 to 3.5 is desirable from the viewpoint of compatibility with other components and adhesion of the formed coating film.

  In the present invention, the aqueous dispersion (A) of the modified polyolefin is obtained by dispersing the unsaturated carboxylic acid or acid anhydride modified polyolefin (a) in an aqueous medium. It is obtained by neutralizing a part or all of the carboxyl groups in the saturated carboxylic acid or acid anhydride-modified polyolefin (a) with an amine compound and / or dispersing in water with an emulsifier. When the modified polyolefin (a) has a polyoxyalkylene chain, the modified polyolefin (a) can be dispersed in an aqueous medium without using the amine compound or the emulsifier or by using a small amount.

  Examples of the amine compound include tertiary amines such as triethylamine, tributylamine, dimethylethanolamine, and triethanolamine; secondary amines such as diethylamine, dibutylamine, diethanolamine, and morpholine; and primary amines such as propylamine and ethanolamine. can give.

  When the amine compound is used, the amount used is in the range of 0.1 to 1.0 molar equivalent to the carboxyl group in the unsaturated carboxylic acid or anhydride modified polyolefin (a). Is desirable.

  Examples of the emulsifier include polyoxyethylene monooleyl ether, polyoxyethylene monostearyl ether, polyoxyethylene monolauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Ethylene octylphenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan mono Nonionic emulsifiers such as laurate; sodium salts such as alkylsulfonic acid, alkylbenzenesulfonic acid, alkylphosphoric acid Anionic emulsifiers such as ammonium salts are included, and polyoxyalkylene group-containing anionic emulsifiers having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule or in one molecule Examples thereof also include a reactive anionic emulsifier having the anionic group and a polymerizable unsaturated group, and these can be used alone or in combination of two or more.

  The amount of the emulsifier used is 30 parts by weight or less, preferably 0.5 to 25 parts by weight, based on 100 parts by weight of the solid content of the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a). Is desirable.

  In the present invention, the resin (B) is a resin having at least one crosslinkable functional group selected from a carbodiimide group, an oxazoline group, and a carbonyl group.

  The carbodiimide group-containing resin can be obtained, for example, by reacting the isocyanate groups of the polyisocyanate compound with each other, and examples of the commercially available products include “Carbodilite V-02” and “Carbodilite V-02-”. “L2”, “Carbodilite V-04”, “Carbodilite E-01”, “Carbodilite E-02” (all manufactured by Nisshinbo Co., Ltd.) and the like can be used.

  As the oxazoline group-containing resin, a polymer having an oxazoline group, for example, a polymerizable unsaturated monomer having an oxazoline group, and other polymerizable unsaturated monomers as necessary, and a conventionally known method (for example, solution polymerization, emulsion polymerization, etc.) (Co) polymers obtained by copolymerization with can be mentioned.

  Examples of the polymerizable unsaturated monomer having an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl. -2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like.

  Examples of the other polymerizable unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate. Alkyl or cycloalkyl esters of 1 to 24 carbon atoms of (meth) acrylic acid such as lauryl (meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and the like (Meth) acrylic acid hydroxyalkyl ester having 2 to 8 carbon atoms; vinyl aromatic compounds such as styrene and vinyltoluene; (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (Meth) acrylate, adduct of glycidyl (meth) acrylate and amines; polyethylene glycol (meth) acrylate; N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, (meth) acrylonitrile, etc. It is done. These may be selected singly or in appropriate combination of two or more.

  The copolymerization ratio of the above-mentioned polymerizable unsaturated monomer having an oxazoline group and other polymerizable unsaturated monomers is such that the storage property, water resistance at the time of thick film formation, gasohol resistance, and the like are polymerizable with an oxazoline group. It is appropriate that the unsaturated monomer is 3 to 40% by weight, preferably 5 to 30% by weight, and the other polymerizable unsaturated monomer is 60 to 97% by weight, preferably 70 to 95% by weight.

  The number average molecular weight of the oxazoline group-containing resin is 500 to 100,000, preferably 1,000 to 50,000, and more preferably 3,000 to 30,000. The obtained oxazoline group-containing resin is desirably either water-soluble or water-dispersible.

  When the carbodiimide group-containing resin and / or oxazoline group-containing resin is used as the component (B), it can react with the carboxyl group in the aqueous dispersion (A) of the modified polyolefin.

  As the carbonyl group-containing resin, for example, a polymer having a carbonyl group, for example, a polymerizable unsaturated monomer having a carbonyl group, if necessary, other polymerizable unsaturated monomers and conventionally known methods (for example, solution polymerization, emulsion polymerization, etc.) And (co) polymers obtained by copolymerization.

  Examples of the polymerizable unsaturated monomer having a carbonyl group include acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, and vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl ketone). Vinyl ethyl ketone, vinyl butyl ketone) and the like. Of these, diacetone acrylamide and diacetone methacrylamide are particularly suitable.

  The other polymerizable unsaturated monomer copolymerizable with the polymerizable unsaturated monomer having a carbonyl group is appropriately selected from the other polymerizable unsaturated monomers listed in the description of the oxazoline group-containing resin. Can do.

  The production of the polymer having a carbonyl group may be carried out by emulsion polymerization in multiple stages using the above polymerizable unsaturated monomer having a carbonyl group and other polymerizable unsaturated monomers. The monomer mixture forming the component is subjected to the first stage emulsion polymerization using a polymerization initiator in the presence of an emulsifier to obtain a polymer aqueous dispersion, and then the outer layer component is formed in the aqueous dispersion. The monomer mixture is subjected to emulsion polymerization in the second and subsequent steps in the same manner by using an emulsifier and a polymerization initiator, whereby an aqueous dispersion of an emulsion polymer having a multilayer structure can be obtained.

  The copolymerization ratio of the above-mentioned polymerizable unsaturated monomer containing a carbonyl group and other polymerizable unsaturated monomers is a polymerizable unsaturated monomer containing a carbonyl group in terms of storage stability, water resistance at the time of thick film formation, etc. It is appropriate that the monomer is 3 to 40% by weight, preferably 5 to 30% by weight, and the other polymerizable unsaturated monomer is 60 to 97% by weight, preferably 70 to 95% by weight.

  As the carbonyl group-containing resin, a ketone resin obtained by condensation of ketones (cyclohexanone, methylcyclohexanone, acetophenone, etc.) and formaldehyde can also be used, and a hydrogenated product of the obtained ketone moiety should also be used. Can do.

  When the carbonyl group-containing resin is used as the component (B), it is desirable to add a hydrazide group-containing compound or a semicarbazide group-containing compound to the composition of the present invention. Examples of the hydrazide group-containing compound include saturated dicarboxylic acid dihydrazides having 2 to 18 carbon atoms such as oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide; Monoolefinic unsaturated dicarboxylic acid dihydrazide such as acid dihydrazide, fumarate dihydrazide, itaconic acid dihydrazide; phthalic acid dihydrazide, terephthalic acid dihydrazide or isophthalic acid dihydrazide; pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotrihydrazide Trihydrazide, 1,2,4-benzenetrihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tet Hydrazides; polyhydrazide obtained by reacting a carboxylic acid lower alkyl ester group oligomer hydrazine or hydrazine hydrate with (hydrazine human Dorado); carbonate dihydrazide and the like.

  Examples of the semicarbazide group-containing compound include bissemicarbazide; diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate or polyisocyanate compounds derived therefrom, N, N-substituted hydrazines such as N, N-dimethylhydrazine, and the hydrazides exemplified above. Examples of the polyfunctional semicarbazide obtained by excessively reacting the polyisocyanate, the isocyanate group in the reaction product of the polyisocyanate compound, the polyether, and an active hydrogen compound containing a hydrophilic group such as a polyol or polyethylene glycol monoalkyl ether An aqueous polyfunctional semicarbazide obtained by excessively reacting a dihydrazide of the above; a compound having a semicarbazide group such as a mixture of the polyfunctional semicarbazide and the aqueous polyfunctional semicarbazide; bisacetyldihydride Compounds and the like having a hydrazone group Zon like.

  In the hydrazide group-containing compound or semicarbazide group-containing compound, the hydrazide group in the hydrazide group-containing compound or the semicarbazide group in the semicarbazide group-containing compound is 0.01 to 2 with respect to 1 mol of the carbonyl group contained in the carbonyl group-containing resin. It is desirable to blend so as to be about a mole.

    In the present invention, the use ratios of the components (A) and (B) are (A) / (B) from the viewpoints of storage stability, water resistance at the time of thick film formation, gasohol resistance, and further solvent resistance and scratch resistance. It is desirable that the solid content weight ratio of (B) is within the range of 10/90 to 80/20, preferably 25/75 to 70/30.

  The aqueous composition of the present invention contains the pigment (C). Examples of the pigment (C) include conductive pigments, colored pigments, extender pigments, and the like. In particular, by using conductive pigments, a conductive coating film useful as a primer can be obtained, and thereby the top coating can be statically stopped. It can be electropainted and is also useful for interior use from the viewpoint of antistatic.

  The conductive pigment is not particularly limited as long as it can impart conductivity to the coating film to be formed, and can be any one of particles, flakes, fibers (including whiskers), etc. For example, conductive carbon such as conductive carbon black, carbon nanotube, carbon nanofiber, and carbon microcoil, and metal powder such as silver, nickel, copper, graphite, and aluminum can be used. . In addition, tin oxide doped with antimony, tin oxide doped with phosphorus, acicular titanium oxide surface coated with tin oxide / antimony, antimony oxide, zinc antimonate, indium tin oxide, carbon and graphite whiskers Pigment coated with tin oxide, etc .; selected from the group consisting of tin oxide, antimony-doped tin oxide, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), phosphorus-doped tin oxide and nickel oxide on the surface of flake mica Examples include pigments coated with at least one conductive metal oxide; pigments having conductivity containing tin oxide and phosphorus on the surface of titanium dioxide particles, and these can be used alone or in combination of two or more. .

Among these, it is preferable to use conductive carbon, and in particular, conductive carbon having a specific surface area of 400 m ² / g or more, preferably 600 m ² / g or more can be suitably used.

  Examples of the color pigment include titanium dioxide, bengara, aluminum paste, azo series, and phthalocyanine series. Examples of extender pigments include talc, silica, calcium carbonate, barium sulfate, and zinc white (zinc oxide). These may be used alone or in combination of two or more. In particular, for interior use, a matte coating film can be formed by appropriately adding extender pigments such as talc and barium sulfate.

  When the composition of the present invention is used as a paint having high brightness, it is desirable to contain a white pigment as the pigment (C), particularly titanium oxide, and in terms of design properties and chemical resistance, the average particle It is preferable to use those having a diameter in the range of about 0.05 to about 2 μm, particularly 0.1 to 1 μm.

  The amount of the pigment (C) used is 0.5 to 200 parts by weight, preferably 1 to 150 parts, based on 100 parts by weight of the total resin solids in the composition, from the viewpoints of adhesion of the formed coating film, water resistance, and the like. Within the range of parts by weight. Of these, when using conductive carbon, the amount used is within the range of 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the total resin solid content in the composition. Is desirable. Furthermore, when using the white pigment, the content is desirably selected so that the L value of the formed coating film is 35 or more, and is usually based on 100 parts by weight of the total resin solid content in the composition. A suitable range is 50 to 150 parts by weight, preferably 70 to 130 parts by weight.

  The aqueous coating composition of the present invention comprises a resin (B) and a pigment having at least one crosslinkable functional group selected from the above-described aqueous dispersion (A) of modified polyolefin, carbodiimide group, oxazoline group and carbonyl group. It can be prepared by blending (C) according to a conventional method and appropriately diluting with an aqueous medium such as deionized water.

  In this invention, the acrylic resin (D) containing an ionic functional group can further be mix | blended as needed. As the resin (D), any conventionally known acrylic resin can be used without particular limitation as long as it has an ionic functional group. Particularly, the ionic functional group is a tertiary amino group, a quaternary ammonium base, or a sulfonic acid. It is preferably at least one selected from carboxylate groups having a group, a phosphate group, or a quaternary ammonium salt as a counter ion. The resin (D) is particularly preferably used as a pigment dispersion resin when the pigment (C) described later is dispersed.

  The resin (D) can be usually obtained by copolymerizing an ionic functional group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer.

  Examples of the ionic functional group-containing polymerizable unsaturated monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N , N-di-t-butylaminoethyl (meth) acrylate, tertiary amino group-containing polymerizable unsaturated monomer such as N, N-dimethylaminobutyl (meth) acrylate; 2- (methacryloyloxy) ethyltrimethylammonium chloride, 2 -(Meth) acryloyloxyalkyltrialkylammonium salts such as (methacryloyloxy) ethyltrimethylammonium bromide, 2- (methacryloyloxy) ethyltrimethylammonium dimethyl phosphate; methacryloylaminopropyltrimethyl (Meth) acryloylaminoalkyltrialkylammonium salts such as ruammonium chloride and methacryloylaminopropyltrimethylammonium bromide; tetraalkyl (meth) acrylates such as tetrabutylammonium (meth) acrylate; trialkyls such as trimethylbenzylammonium (meth) acrylate Quaternary ammonium base-containing polymerizable unsaturated monomers such as benzylammonium (meth) acrylate; (meth) acrylamide-alkanesulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid; 2-sulfoethyl (meth) acrylate and the like Sulfonic acid group-containing polymerizable unsaturated monomers such as sulfoalkyl (meth) acrylate; 2-methacryloyloxyethyl acid phos , 2-allyloyloxyethyl acid phosphate, monoalkyl (butyl, decyl, lauryl, stearyl, etc.), a polymerizable unsaturated monomer obtained by adding glycidyl methacrylate to phosphoric acid, glycidyl methacrylate added to benzyl phosphate Examples thereof include phosphoric acid group-containing polymerizable unsaturated monomers such as polymerizable unsaturated monomers; quaternary ammonium chloride carboxyl group-containing polymerizable unsaturated monomers. These monomers can be used alone or in combination of two or more.

The other polymerizable unsaturated monomer is a polymerizable unsaturated monomer other than the above monomer, which can be copolymerized with the above monomer, and is appropriately selected according to the characteristics desired for the resin. Examples of the other polymerizable unsaturated monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, tridecyl (meth) _C 1 _{-C 24} linear or cyclic alkyl acrylates such as (meth) acrylate monomers; 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydro Hydroxyl group-containing polymerizable unsaturated monomers such as sibutyl (meth) acrylate; carboxyl group-containing polymerizable unsaturated monomers such as methacrylic acid and acrylic acid; acrylamide, methacrylamide; 3-ethyl-3- (meth) acryloyloxymethyloxetane; Oxetane ring-containing (meth) acrylates such as 3-methyl-3- (meth) acryloyloxymethyloxetane and 3-butyl-3- (meth) acryloyloxymethyloxetane; aromatics such as styrene, α-methylstyrene and vinyltoluene Examples of the vinyl compound include (meth) acrylonitrile and vinyl acetate. These polymerizable unsaturated monomers can be used alone or in combination of two or more.

  In the present invention, it is desirable that the acrylic resin (D) containing an ionic functional group further contains a polyoxyalkylene chain from the viewpoint of water dispersibility and conductivity. In order to introduce the polyoxyalkylene chain, For example, this can be achieved by copolymerizing a polymerizable unsaturated monomer having a polyoxyalkylene chain with the ionic functional group-containing polymerizable unsaturated monomer or other ethylenically unsaturated monomer during the production of the resin (D).

  Examples of the polymerizable unsaturated monomer having a polyoxyalkylene chain include tetraethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, ethoxytetraethylene glycol (meth) acrylate, n-butoxytetraethylene glycol (meta ) Acrylate, tetrapropylene glycol (meth) acrylate, methoxytetrapyrene glycol (meth) acrylate, ethoxytetrapropylene glycol (meth) acrylate, n-butoxytetrapropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (Meth) acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethyleneglycol , And the like Lumpur (meth) acrylate. Among these, polyethylene glycol (meth) acrylate and polypropylene glycol (meth) acrylate are particularly preferable. These can be used alone or in combination of two or more.

  In the production of the resin (D), the use ratio of the polymerizable unsaturated monomer containing an ionic functional group, the polymerizable unsaturated monomer having a polyoxyalkylene chain, and other polymerizable unsaturated monomers is determined by pigment dispersibility and conductivity. From the viewpoint of safety, the polymerizable unsaturated monomer containing an ionic functional group is 0.5 to 20% by weight, preferably 1 to 15% by weight, and the polymerizable unsaturated monomer having a polyoxyalkylene chain is 10 to 30% by weight. %, Preferably 15 to 25% by weight, and other polymerizable unsaturated monomers in the range of 50 to 89.5% by weight, preferably 60 to 84% by weight. These copolymerizations can be carried out by a method known per se, for example, a solution polymerization method in an organic solvent, an emulsion polymerization method in water, etc. Among them, the solution polymerization method is preferable.

  The resin (D) has a weight average molecular weight of about 5,000 to 300,000, preferably 10,000 to 50,000. The weight average molecular weight of the acrylic resin (B) is a value obtained when the weight average molecular weight measured by gel permeation chromatography is converted on the basis of the weight average molecular weight of polystyrene using tetrahydrofuran as a solvent. “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) can be used for the gel permeation chromatography apparatus, and columns used for gel permeation chromatography include “TSKgel G-4000H × L” and “TSKgel G-”. Four pieces of “3000H × L”, “TSKgel G-2500H × L”, and “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation) are used.

  The resin (D) can be water-solubilized by neutralization with a neutralizing agent as necessary. The blending amount of the resin (D) is 30% by weight or less, preferably 10 to 25% by weight in the total resin solid content in the composition from the viewpoint of pigment dispersibility, water resistance of the formed coating film, conductivity and the like. It is desirable to be within the range.

  In the composition of the present invention, a urethane resin can be further contained as a vehicle component as required. Such a urethane resin is a water-soluble or water-dispersible resin having a urethane bond in the molecule, and examples thereof include self-emulsifying emulsions having an acid value, emulsions in combination with emulsifiers, and water-soluble resins. Is preferred. Urethane dispersion is usually emulsified or self-emulsified while dispersing in water the urethane prepolymer obtained by reacting diol and diisocyanate in advance in the presence of an emulsifier, and if necessary, dimethylolalkanoic acid. Is a dispersion obtained by

  Examples of the skeleton of the urethane resin include ethers, carbonates, and esters. Among these, ethers and carbonates are desirable from the viewpoint of water resistance of the formed film. The urethane resin may contain a hydroxyl group.

  From the viewpoint of improving the physical properties of the coating film, the urethane resin is desirably blended so as to be in the range of 50% by weight or less, particularly 10 to 40% by weight in the total resin solid content in the composition.

  The composition of the present invention may further contain a water-soluble or water-dispersible resin other than the urethane resin as necessary. Examples of the water-soluble or water-dispersible resin include the resin (B). And acrylic resins other than the resin (D), polyester resins, grafted products of these resins, acrylic-modified or polyester-modified epoxy resins, and self-crosslinking resins such as blocked isocyanate group-containing polyester resins. A water-dispersible acrylic resin or a water-soluble or water-dispersible polyester resin is preferred.

  The composition of the present invention can further contain a compound that adsorbs or decomposes an aldehyde compound such as formalin, if necessary, for use in interior parts. As such a compound, a conventionally known compound that adsorbs or decomposes formalin or the like can be used without particular limitation, and examples thereof include amine compounds, crystalline layered phosphate compounds, and porous materials. These can be used alone or in combination of two or more, and the blending amount thereof is suitably in the range of 0.01 to 25 parts by weight in the solid content of the composition.

  Examples of the amine compound include compounds having an amino group, a hydrazide group, a urea bond, an amide group, or an imide group. Examples of the compound having an amino group include hydroxylamine, chloramine, ammonia, methanolamine, ethanolamine, dimethylamine, diethylamine, isopropylamine, butylamine, proline, hydroxyproline, dicyanodiamide, ethyleneimine, ethylenediamine, propylenediamine, diethylenetriamine, 1,2-diaminopropane, 1,3-diaminopropane, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, hexamethylenediamine, morpholine, 2-amino-4,5-dicyanoimidazole, 3-azahexane-1 , 6-diamine, 2-acrylamido-2-methylpropanesulfonic acid, α-amino-ε-caprolactam, acetoguanamine, acetaldehyde Ammonia, 4,7-diazadecane-1,10-diamine, pyrrolidine, piperidine, piperazine and the like can be mentioned. Examples of the compound having a hydrazide group include saturated aliphatic carboxylic acid dihydrazides having 2 to 18 carbon atoms such as oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide; Monoolefinic unsaturated dicarboxylic acid dihydrazide such as acid dihydrazide, fumarate dihydrazide, itaconic acid dihydrazide; phthalic acid, terephthalic acid or isophthalic acid dihydrazide, and pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotriacetic acid trihydrazide, citrate Acid trihydrazide, 1,2,4-benzenetrihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide ; Dihydrazide carbonate, bis semicarbazide. Examples of the compound having a urea bond include urea, thiourea, methylurea, ethylurea, dimethylurea, diethylurea, ethyleneurea, guanylurea, guanylthiourea, azodicarbonamide, glycolylurea, acetylurea and the like. Examples of the compound having an amide group include formamide, acetamide, benzamide, oxamide, oxamic acid, succinic acid amide, and malonamide. Examples of the compound having an imide group include succinimide, phthalimide, maleimide, 1-methylol-5,5-dimethylhydantoin, and isocyanuric acid. These amine compounds can be used alone or in combination of two or more. When using a hydrazide group containing compound among these, when using the above-mentioned carbonyl group containing resin as (B) component, a compounding quantity can be selected so that it may become more than the quantity required for bridge | crosslinking.

  As the crystalline layered phosphate compound, for example, a compound obtained by intercalating a polyamine compound as described above into a layered phosphate compound, or a metal ion having an antibacterial action such as zinc or silver ion is intercalated into the crystalline layered phosphate compound. In addition, a compound obtained by intercalating a quaternary ammonium salt or a thiazole compound with a crystalline layered phosphoric acid compound (herein, “intercalate” means mainly a layered compound or a layered product). Ion exchange with cations between layers). These can be used alone or in combination of two or more.

  Examples of the porous material include activated alumina, activated clay, zeolite, diatomaceous earth, activated carbon, and ceramic activated carbon. These can be used alone or in combination of two or more.

  The composition of the present invention may further include a curing catalyst, a rheology control agent, a resin fine particle, an antifoaming agent, a surface conditioner, an ultraviolet absorber, an antioxidant, an antiseptic, an antifungal agent, a plasticizer, and an organic material as necessary. An additive for paint such as a solvent can be appropriately contained.

  The aqueous coating composition of the present invention obtained as described above can be applied to a plastic molded product.

  Plastic molded products include, for example, automobile exterior parts such as bumpers, spoilers, grills, and fenders; automobile interior parts such as dashboards, instrumental panels, and handles; plastics used in exterior parts of home appliances, etc. Examples of the material include polyolefins obtained by (co) polymerizing one or more of 2 to 10 carbon olefins such as ethylene, propylene, butylene and hexene. However, the composition of the present invention can also be applied to polycarbonate, ABS resin, urethane resin, polyamide and the like.

  Prior to the application of the composition of the present invention, these plastic molded products can be appropriately subjected to a degreasing treatment, a water washing treatment and the like by a method known per se.

  The coating of the composition of the present invention is usually applied to the object to be coated so that the dry film thickness is 1 to 50 μm, preferably 5 to 45 μm in the primer application, and in the one-coat finishing application. Air spray, airless spray, dip coating, brush, etc. can be used so that the thickness is in the range of 5 to 50 μm, preferably 10 to 40 μm. After coating of the composition, the resulting coating surface can be set at room temperature for 1 to 60 minutes as necessary, or preheated at a temperature of about 40 to 80 ° C. for 1 to 60 minutes, or about 60 to It can be cured by heating at a temperature of about 140 ° C., preferably about 60 to about 120 ° C. for about 20 to 40 minutes.

The coating film formed as described above preferably has a surface resistivity of 1 × 10 ⁸ Ω / □ or less for primer use. This makes it possible to perform good electrostatic coating in the next step as a conductive primer coating. In this specification, the “surface resistivity” is measured by drying a coating film coated so that the dry film thickness is about 5 to 15 μm at 80 ° C. for 10 minutes, and then surface resistance manufactured by TREK. This can be done using the trade name “TREK MODEL 150” (unit: Ω / □).

  The formed coating film has an L value of 35 or more, preferably 40 to 80. Here, the L value is the CIE 1976 color system of the coating film when the composition of the present invention is coated on a plastic plate in a concealing film thickness (usually 5 to 15 μm in dry film thickness) and baked and cured. The L value is measured with a color difference meter. It shows that whiteness is so high that L value is large.

  In the coating method of the present invention, the water-based paint composition obtained as described above can be applied to a plastic molded product to make one coat finish, and the water-based paint composition obtained as described above can be used as a primer to form a plastic molded product. It can be painted and then a top coat can be applied to the coated surface. As the top coating, a colored coating may be used alone, or a base coating and a clear coating may be sequentially applied using the colored coating as a base coating.

  The colored base paint usually contains an organic solvent and / or water as a main solvent, and mainly contains colored components such as colored pigments, bright pigments and dyes, and resin components such as a base resin and a crosslinking agent.

  Examples of the base resin used in the colored base paint include acrylic resins having a crosslinkable functional group such as a hydroxyl group, an epoxy group, a carboxyl group, and a silanol group, a polyester resin, and an alkyd resin. Examples of the crosslinking agent include amino resins such as melamine resin and urea resin that can react with these functional groups, (block) polyisocyanate, polyepoxide, and polycarboxylic acid.

  For the above colored base paint, additives for paints such as extender pigment, curing catalyst, UV absorber, coating surface preparation agent, rheology control agent, antioxidant, antifoaming agent, wax, preservative, etc. Etc. can be contained appropriately.

  The colored base coating is usually electrostatically coated so that the dry film thickness is in the range of 5 to 50 μm, preferably 10 to 20 μm, and the obtained coating surface is 1 to 60 at room temperature as necessary. It can be set for about 4 minutes, preheated at about 40-80 ° C for 1-60 minutes, or heated at about 60-140 ° C, preferably about 80-120 ° C for 20-40 minutes for curing. be able to.

  The clear coating used in the method of the present invention mainly contains a base resin, a resin component such as a crosslinking agent, an organic solvent, water, and the like, and further, if necessary, an ultraviolet absorber, a light stabilizer, a curing catalyst, a coating. It is an organic solvent-based or water-based thermosetting coating that contains paint additives such as surface conditioners, rheology control agents, antioxidants, antifoaming agents, and waxes. It has transparency to the extent that the coating film can be visually recognized.

  Examples of the base resin include acrylic resins, polyester resins, alkyd resins, fluororesins, urethane resins, and silicon-containing resins containing at least one crosslinkable functional group such as a hydroxyl group, a carboxyl group, a silanol group, and an epoxy group. A hydroxyl group-containing acrylic resin is particularly suitable. Examples of the crosslinking agent include melamine resin, urea resin, (block) polyisocyanate compound, epoxy compound, carboxyl group-containing compound, acid anhydride, alkoxysilane group-containing compound, etc., which can react with these functional groups. Isocyanate compounds are preferred.

  The clear coating is applied electrostatically so that the dry film thickness is within a range of 10 to 50 μm, preferably 15 to 40 μm, and the obtained coating surface is applied at room temperature for 1 to 60 minutes as necessary. After setting or preheating at about 40 to 80 ° C. for 1 to 60 minutes, it can be cured by heating at about 60 to 140 ° C., preferably about 70 to 120 ° C. for 20 to 40 minutes.

  Hereinafter, the present invention will be described in more detail with reference to examples. “Part” and “%” indicate “part by weight” and “% by weight” unless otherwise specified.

Manufacture of carbonyl group-containing resin water dispersion (B-1) 312 parts of deionized water, “Newcol 707SF” (Note 1) in a 2-liter 4-neck flask equipped with a reflux condenser, stirrer, thermometer and dropping funnel ) 0.9 part was added and kept at 80 ° C. after nitrogen substitution. To this, 0.4 part of ammonium persulfate was added, and 15 minutes after the addition, a pre-emulsion formed by emulsifying the following composition was added dropwise over 140 minutes.

210 parts deionized water
Methyl methacrylate 118.56 parts
312 parts of n-butyl acrylate
Acrylic acid 1.44 parts
"Newcol 707SF" 37.3 parts
0.48 parts ammonium persulfate

  After ripening for 1 hour after the completion of dropping, a pre-emulsion obtained by emulsifying the following composition was dropped over 60 minutes.

140 parts deionized water
Methyl methacrylate 207.04 parts
96 parts of n-butyl acrylate
Acrylic acid 0.96 parts
16 parts of diacetone acrylamide
"Newcol 707SF" 21.3 parts
0.32 parts ammonium persulfate

  After ripening for 30 minutes after the completion of dropping, a solution prepared by dissolving 0.8 part of ammonium persulfate in 7 parts of deionized water was added dropwise over 30 minutes and maintained at 80 ° C. for 2 hours. Thereafter, the temperature was lowered to 40 to 60 ° C., the pH was adjusted to 7 to 8 with aqueous ammonia, and a copolymer emulsion (B-1) having a nonvolatile content of 53.6% was obtained.

  (Note 1) “Newcol 707SF”: trade name, manufactured by Nippon Emulsifier Co., Ltd., an anionic emulsifier having a polyoxyethylene chain, 30% active ingredient.

Production of hydroxyl-containing acrylic emulsion (B-2) The following components were placed in a glass beaker and stirred at 2000 rpm for 15 minutes with a disper to produce a pre-emulsified liquid. A monomer emulsion having an average particle size of dispersed particles of 230 nm was obtained by high-pressure treatment at 150 MPa with a high-pressure emulsifying device for collision.

Monomer emulsion composition Cyclohexyl methacrylate 33 parts 2-ethylhexyl acrylate 55 parts 2-hydroxyethyl acrylate 10 parts Acrylic acid 2 parts "Newcol 707SF" (Note 1) 15 parts Deionized water 85 parts It moved to the glass reaction container provided with the pipe | tube, the nitrogen gas inlet tube, and the thermometer, and diluted so that solid content concentration might be 45% with deionized water. Thereafter, the temperature was raised to 85 ° C., an aqueous polymerization initiator solution in which 1 part of ammonium persulfate was dissolved in 9.4 parts of deionized water was added to the reaction vessel, and the mixture was stirred for 3 hours while maintaining the temperature under a nitrogen stream. Thereafter, an aqueous polymerization initiator solution in which 0.3 part of ammonium persulfate was dissolved in 3 parts of deionized water was added, stirred for 1 hour while maintaining the temperature, cooled to 40 ° C., and adjusted to pH 8 with dimethylethanol. To obtain a hydroxyl group-containing acrylic emulsion (B-2) having a solid content concentration of 43%.

Production of ionic functional group-containing resin (D-1) 35 parts of ethylene glycol monobutyl ether was charged in a normal acrylic resin reaction vessel equipped with a stirrer, thermometer and reflux condenser, and heated to 110 ° C with stirring. did. In this, 10 parts of styrene, 40 parts of methyl methacrylate, 25 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 3 parts of methacrylic acid, 5 parts of N, N-dimethylaminoethyl methacrylate (solid content, deionized water) 10 parts dissolved in 10 parts), “NF biisomer PEM6E” (Daiichi Kogyo Seiyaku Co., Ltd., trade name, polyethylene glycol monomethacrylate, molecular weight about 350), 10 parts azobisisobutyronitrile and isobutyl alcohol A mixture of 20 parts was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was aged at 110 ° C. for 30 minutes, and then an additional catalyst mixture composed of 15 parts of ethylene glycol monobutyl ether and 0.5 part of azobisisobutyronitrile was added dropwise over 1 hour. Next, the mixture was aged at 110 ° C. for 1 hour and then cooled to obtain an ionic functional group-containing resin (D-1) solution having a solid content of 55%. The resin (D-1) had a hydroxyl value of 43 mgKOH / g and a weight average molecular weight of about 20,000.

Preparation Example 1 of water-based paint
Aqueous polypropylene / ethylene copolymer (A-1) (modified with a maleic acid addition amount of 8% by weight with respect to an ethylene-propylene copolymer (ethylene content 5%) obtained using a metallocene catalyst, A compound having a melting point of 80 ° C., an Mw of about 100,000, an Mw / Mn of about 2.1 and an acid value of 35 is neutralized with dimethylethanolamine in an equivalent amount. Part of water dispersion) is 55 parts by weight of solid content, "UX5210" (manufactured by Sanyo Chemical Industries, urethane dispersion) is 20 parts by weight of solid content, "Epocross WS-100" (manufactured by Nippon Shokubai Co., Ltd., oxazoline group) Containing acrylic resin, solid content 40%, oxazoline equivalent 220) in solid weight, 10 parts by weight, ionic functional group-containing resin (D-1) solution in solid weight 15 parts, JR-806 "(the Tayca Corporation, titanium white) 120 parts, were blended in accordance with a conventional method, to obtain an aqueous coating composition (1) was diluted with deionized water to a solid content of 40%.

Example 2
Aqueous polypropylene / ethylene copolymer (A-1) 55 parts by weight in solids, "UX5210" 20 parts by weight in solids, and ionic functional group-containing resin (D-1) solution 15 parts by weight in solids , “Carbodilite V-02” (manufactured by Nisshinbo Co., Ltd., carbodiimide group-containing compound, solid content 40%, carbodiimide equivalent 590) in a solid content weight of 10 parts, “JR-806” 120 parts, A water-based paint (2) was obtained by diluting with deionized water to a solid content of 40%.

Example 3
The aqueous polypropylene / ethylene copolymer (A-1) is 30 parts by weight in solid content, the carbonyl group-containing resin aqueous dispersion (B-1) is 45 parts in weight by solid content, and the ionic functional group-containing resin (D-1). ) 15 parts by weight of the solid content, 10 parts of adipic acid dihydrazide and 120 parts of “JR-806” were blended according to a conventional method, and diluted with deionized water to a solid content of 40%. )

Example 4
The modified polypropylene aqueous dispersion (A-2) (Note 2) is 30 parts by weight in solid content, the carbonyl group-containing resin aqueous dispersion (B-1) is 45 parts by weight in solid content, and the ionic functional group-containing resin ( D-1) 15 parts by weight of solid solution, 10 parts of semicarbazide curing agent (Note 3), 120 parts of “JR-806” were blended in accordance with a conventional method, and deionized water was added so that the solid content was 40%. Dilution was carried out and water-based paint (4) was obtained.
(Note 2) Modified polypropylene aqueous dispersion (A-2): In a four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel, maleic anhydride grafted polypropylene (obtained using a metallocene catalyst) The resulting polypropylene was modified with a maleic acid addition amount of 4% by weight. 100 g of melting point 80 ° C., Mw about 150,000, Mw / Mn about 2.5) was heated and melted at 140 ° C. to obtain polyoxyethylene stearyl ether ( 15 g of “New Coal 1820”, one-terminal hydroxyl group-containing polyoxyethylene compound, manufactured by Nippon Emulsifier Co., Ltd.) was added, and the reaction was carried out at 140 ° C. for 4 hours while stirring. After the reaction, the mixture was cooled to 90 ° C., filtered with deionized water, and an aqueous dispersion of modified polypropylene (A-2) having a solid content of 30% was obtained.
(Note 3) Semicarbazide curing agent: 250 g of 80% hydrazine hydrate and 250 g of methanol were placed in a reaction vessel having a reflux condenser, a thermometer, and a stirrer. Thereafter, 2250 g of methanol and 500 g of isophorone diisocyanate were added dropwise at room temperature over 1 hour while mixing with a static mixer. Then, after further stirring at room temperature for 1 hour, 400 g of dioxane was added, and methanol was removed under reduced pressure at a temperature of 30 ° C. or lower. After standing for a while, a white powder was precipitated, which was filtered off and vacuum dried at room temperature to obtain a semicarbazide curing agent.

Example 5
The modified polypropylene aqueous dispersion (A-3) (Note 4) is 30 parts by weight in solid content, the carbonyl group-containing resin aqueous dispersion (B-1) is 45 parts by weight in solid weight, and the ionic functional group-containing resin ( D-1) 15 parts by weight of solid solution, 10 parts of semicarbazide curing agent (Note 3), 120 parts of “JR-806” were blended in accordance with a conventional method, and deionized water was added so that the solid content was 40%. Dilution was carried out and water-based paint (5) was obtained.
(* 4) Modified polypropylene aqueous dispersion (A-3): In a four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel, maleic anhydride grafted polypropylene (obtained using a metallocene catalyst) The resulting polypropylene was modified with a maleic acid addition amount of 4% by weight, and 200 g of melting point 80 ° C., Mw about 150,000, Mw / Mn about 2.5) was melted by heating at 120 ° C. A polymerization inhibitor (di-t-butylhydroxytoluene) 0.1 g and triethylamine 2.0 g were added and stirred for 1 hour. Thereto, 30 g of polyethylene glycol monomethacrylate (“Blemmer PE-350”, manufactured by NOF Corporation) and 0.3 g of a polymerization initiator (“Perbutyl O”, manufactured by NOF Corporation) were added at 120 ° C. for 1 hour with stirring. The reaction was performed. After the reaction, 4 g of triethylamine was added, stirred for 30 minutes, cooled to 90 ° C., filtered by adding deionized water, and an aqueous dispersion (A-3) of modified polypropylene having a solid content of 30% was obtained.

Comparative Example 1
An aqueous polypropylene / ethylene copolymer (A-4) (modified with a maleic acid addition amount of 8% by weight with respect to an ethylene-propylene copolymer (ethylene content 5%) obtained using a metallocene catalyst, A material having a melting point of 140 ° C., an Mw of about 200,000, and an Mw / Mn of about 2.1 is neutralized with dimethylethanolamine in an equivalent amount. (Dispersion) is 55 parts by weight in solids, "UX5210" is 30 parts by weight in solids, ionic functional group-containing resin (D-1) solution is 15 parts by weight in solids, and 120 parts "JR-806" It mix | blended according to the conventional method, and it diluted with deionized water so that it might become 40% of solid content, and obtained the aqueous coating material (6).

Comparative Example 2
55 parts by weight of aqueous polypropylene / ethylene copolymer (A-1), 30 parts by weight of “UX5210”, and 15 parts by weight of resin containing ionic functional group (D-1) , “JR-806” (120 parts) was blended according to a conventional method, and diluted with deionized water to a solid content of 40% to obtain an aqueous paint (7).

Example 6
30 parts by weight of the aqueous polypropylene / ethylene copolymer (A-1) and 45 parts by weight of the carbonyl group-containing resin aqueous dispersion (B-2), and the ionic functional group-containing resin (D-1). ) 15 parts by weight of the solid content, 10 parts of adipic acid dihydrazide, 80 parts of “JR-806”, 50 parts of activated clay (manufactured by Nippon Kakuhaku Co., Ltd.) according to a conventional method, so that the solid content becomes 40% Was diluted with deionized water to obtain an aqueous paint (8).

Example 7
30 parts by weight of the aqueous polypropylene / ethylene copolymer (A-1) and 45 parts by weight of the carbonyl group-containing resin aqueous dispersion (B-2), and the ionic functional group-containing resin (D-1). ) 15 parts by weight of solid solution, 10 parts of adipic acid dihydrazide, 80 parts of “JR-806”, 50 parts of “activated alumina KC-503” (manufactured by Sumitomo Chemical Co., Ltd.) according to a conventional method, The aqueous coating material (9) was obtained by diluting with deionized water so that the concentration of the aqueous coating material was 9%.

Preparation of test paint 1
Examples 8-12 and Comparative Examples 3-4
The water-based paint prepared as described above is selected as shown in Table 1 on polypropylene (degreased) molded into a bumper and spray-coated so that the dry film thickness is about 40 μm, at 80 ° C. After preheating for 3 minutes, “WBC # 713T” (manufactured by Kansai Paint Co., Ltd., water-based white mica basecoat paint) is applied as a colored base coat paint to a dry film thickness of about 15 μm and preheated at 80 ° C. for 3 minutes. As a clear paint, "Soflex # 450 clear" (manufactured by Kansai Paint Co., Ltd., acrylic urethane-based solvent-type clear paint) is electrostatically coated to a dry film thickness of about 30 μm, and dried by heating at 90 ° C for 30 minutes. Each test paint was prepared.

  Each test paint prepared as described above was subjected to the following performance test. The results are shown in Table 1.

Performance test method (* 1) Initial adhesion: Cut lines with a cutter to reach the substrate surface, make 100 squares with a size of 2mm x 2mm, and stick adhesive cellophane tape on the surface. The number of residual coatings in the squares after peeling it off rapidly at 20 ° C. was examined. ○ is 100 pieces (no peeling), Δ is 99 to 51 pieces, and x is 50 pieces or less.

  (* 2) Water resistance: A part of the bumper coated with each test paint was cut out, immersed in warm water at 40 ° C. for 10 days, pulled up and dried, and then adhered in the same manner as in the above initial adhesion test. A test was conducted to check the number of remaining coating films. Further, the painted surface after drying was visually evaluated. ○ indicates no occurrence of blisters, Δ indicates a state where gloss is lost, and × indicates occurrence of blisters.

  (* 3) Recoat adhesion: Each test coating is allowed to stand at room temperature for 7 days, the same paint is repainted on the coated surface and cured, and then left at room temperature for 3 days. The adhesion test was conducted in the same manner.

  (* 4) Gasohol resistance: A part of the painted bumper is cut out and immersed in a test solution of gasoline / methanol = 90/10 weight ratio at 20 ° C, blistering after 30 minutes, peeling off at the end, etc. When the coating surface condition is observed, if there is no abnormality, bulge of 3 mm or less, peeling is △, bulging is over 3 mm and 5 mm or less, peeling is △, blistering is over 5 mm, peeling is x .

Preparation of test paint 2
Examples 13 to 19 and Comparative Examples 5 and 6
The polypropylene (degreased) plate is selected as shown in Table 2, and the water-based paint prepared as described above is spray-coated to a dry film thickness of about 25 μm, and heated and dried at 70 ° C. for 15 minutes. Each test paint was created.

  Each test paint prepared as described above was subjected to the following performance test. The results are shown in Table 2.

Performance test method (* 5) Initial adhesion: Cut lines with a cutter to reach the substrate surface, make 100 squares of 2mm x 2mm size, and stick adhesive cellophane tape on the surface. The number of residual coatings in the squares after peeling it off rapidly at 20 ° C. was examined. ○ is 100 pieces (no peeling), Δ is 99 to 51 pieces, and x is 50 pieces or less.

  (* 6) Moisture resistance: The substrate coated with each test paint was allowed to stand at 98 ° C. under 98% RH for 10 days, and then the adhesion test was performed in the same manner as the above initial adhesion test. The number of remaining coating films was examined. Further, the painted surface after drying was visually evaluated. ○ indicates no occurrence of blisters, Δ indicates a state where gloss is lost, and × indicates occurrence of blisters.

  (* 7) Solvent resistance: Ten sheets of gauze dampened with xylene were layered on the coated substrate, and the load was reduced to about 9.8 N and rubbed 8 times. When no reduction in gloss is observed, it is indicated by ○, and when there is a clear reduction in gloss, it is indicated by ×.

(* 8) scratch resistance: 6 ply at 0.1 kg / cm ² load Trang Bath type abrasion tester at broad cloth (JIS L0803 (white cotton) No. 3), 100 mm stroke, for 30 reciprocations / min speed And 5000 times. When the substrate is not exposed, it is indicated by ○, and when it is exposed, it is indicated by ×.

  (* 9) Formalin catcher ability: The above water-based paints were coated on a surface of a 20 × 50 mm glass plate with an applicator having a gap of 150 μm and dried at room temperature for 7 days to prepare test pieces. Four test pieces and 100 mg of 1% formaldehyde aqueous solution were sealed in a 2 liter glass container, and after 24 hours, the formaldehyde concentration was quantified with a detector tube (91 L, manufactured by Gastec). The formaldehyde absorption capacity was evaluated from the obtained formaldehyde concentration in accordance with the following criteria. 1 ppm or less is indicated by ◎, 1-20 ppm is indicated by ○, 20-30 ppm is indicated by Δ, and 30 ppm or more is indicated by ×.

Claims (10)

(A) A modified polyolefin obtained by dispersing an unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) having a melting point of 120 ° C. or less and a weight average molecular weight in the range of 30,000 to 200,000 in an aqueous medium. A water-based coating composition comprising: (B) a resin having at least one crosslinkable functional group selected from a carbodiimide group, an oxazoline group, and a carbonyl group; and (C) a pigment. 2. The aqueous coating composition according to claim 1, wherein the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight of the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is 1.5 to 4.0. The aqueous coating composition according to claim 1 or 2, wherein the polyolefin in the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is produced using a single site catalyst as a polymerization catalyst. The water-based coating composition according to any one of claims 1 to 3, wherein the unsaturated carboxylic acid or anhydride-modified polyolefin (a) is modified with a compound having a polyoxyalkylene chain. The water-based coating composition according to claim 1, wherein the weight ratio of (A) / (B) is in the range of 10/90 to 80/20. The aqueous coating composition according to claim 1, wherein the pigment (C) contains a white pigment. The water-based paint composition according to claim 1, wherein the pigment (C) contains conductive carbon. A method for coating a plastic molded product, comprising applying the water-based coating composition according to any one of claims 1 to 7 to a plastic molded product. A method for coating a plastic molded article, comprising: coating a plastic molded article with the water-based paint composition according to any one of claims 1 to 7 as a primer, and then applying a top coat to the coated surface. . A coated article obtained by the coating method according to claim 8 or 9.