JP2009178652A - Method for forming coating film and coated article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated article by making use of starch of vegetable origin that is excellent in finishing, pencil hardness, abrasion-proof, adhesion, alkali resistance and solvent resistance. <P>SOLUTION: (1) The method for forming coating film is characterized in that an article to be coated is coated with a starch-based coloring base paint containing a starch-based resin and then with a photo-curable paint (A) containing methacrylic ester (a1) of modified starch and a photopolymerization initiator (a2) followed by being exposed to light. (2) The method for forming coating film is further characterized in that the photo-curable paint (A) contains a photo-curable compound (a3). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is obtained by laminating a coating film made of a starch-based colored base paint using plant-derived starch and a coating film made of a photocurable paint containing a methacrylic ester of a modified starch on the coating film. The present invention relates to a method for forming a coating film.

In recent years, from the perspective of reducing the impact on global warming, there has been a demand for a reduction in CO ₂ emissions at a global level, and this is a renewable resource that increases CO ₂ emissions in the carbon dioxide circulation on the earth. There is a demand for positive use of plant-derived materials that are not allowed to occur.

  As a typical material derived from such a natural product, modified starches such as polysaccharide starch and acetylated starch have been conventionally used, and have been used in the food industry and paper industry. Furthermore, in recent years, these starches and modified starches have been commercialized in a wide range of fields such as food containers, packaging materials, cushioning material sheets, agricultural films, and disposable diapers using plastics as raw materials.

  Thus, in order to utilize starch as a raw material for industrial products, various improvements relating to processed starch have been accumulated along with the modification of starch. The basic structure of starch is a mixture of amylose in which α-D-glucose is linearly linked by 1,4-bond and amylopectin having a branched structure, and esterification and ether utilizing the hydroxyl group in the structure. Modifications such as conversion were made in the 1960s.

Conventionally, a method has been disclosed in which a starch resin and an acrylic resin are indirectly grafted via polyisocyanate, and an unsaturated monomer is radical-grafted to starch or modified starch to directly produce graft starch (Patent Document 1). ~ 4).
In addition, as an example of combining starch and other plant-derived resins, an invention using a polymer blend in which starch or modified starch and a cellulose derivative are combined is disclosed as a molding material. In addition, resin compositions such as acrylic acid to starch and a graft polymer of a photocurable resin or a thermosetting resin are disclosed (Patent Documents 5 to 7).

As is clear from these prior patents, a starch-based resin itself obtained by combining, bonding, or grafting various polymers is a known technique. However, in any of these technologies, an adhesive, a structural material, an injection molding material, a sheet, or the like is assumed as an application of the starch-based resin, and an application as a paint is not disclosed.

  In addition, for a paint using a starch-based resin, a curing agent starch composition comprising a mixture of the starch-based resin and a curing agent having a functional group that reacts complementarily with at least one hydroxyl group contained in the starch molecule. It is disclosed that curable types such as an oxidative polymerization curable type, a room temperature curable type, and an active energy ray curable type are possible (Patent Document 8).

Also, starch, polyisocyanate curing agent, plant-derived resin excluding starch, metal complex and β
-A blocking agent selected from diketones, acetoacetic esters, malonic esters, ketones having a hydroxyl group at the β-position, aldehydes having a hydroxyl group at the β-position, and esters having a hydroxyl group at the β-position A curable starch composition is disclosed (Patent Document 9).

  However, coating films obtained by applying these starch-based paints are insufficient in any of finish, pencil hardness, scratch resistance, adhesion, alkali resistance, and solvent resistance.

JP 54-120698 A JP-A-55-90518 JP-A-56-167746 JP-A-8-239402 JP-A-6-207047 JP-A-8-231762 JP 2002-167520 A Japanese Patent Laid-Open No. 2004-224887 JP 2006-282960 A

  An object of the present invention is to provide a coated part that uses a plant-derived starch-based paint and has a laminated coating film excellent in finish, pencil hardness, scratch resistance, adhesion, alkali resistance, and solvent resistance. It is in.

  As a result of intensive studies to solve the above-described problems of the prior art, the present inventors applied a plant-based starch-based colored base paint, and on the coating film, modified starch methacrylate (a1) The present invention has been completed by finding that such a problem can be solved by a method for forming a coating film obtained by coating a photocurable paint (A) containing a photopolymerization initiator (a2).

The coating film forming method of the present invention is formed by laminating a coating film of a photocurable coating containing a specific starch-based resin on a coating film of a plant-derived starch-based colored base coating. Plastic parts painted by such a coating formation method can reduce environmental pollution by reducing the total amount of CO ₂ emissions related to the product life cycle, and the resulting coating film has finish, pencil hardness, and scratch resistance. Excellent in adhesion, adhesion, alkali resistance and solvent resistance.

In the present invention, a starch-based colored base paint is applied onto an object to be coated, and then a photocurable paint (A) containing a specific modified starch methacrylate and a photopolymerization initiator (a2) is applied. It is the coating-film formation method to do. In particular, a part having a multilayer coating film by the coating film forming method of the present invention is useful as a plastic product.

About the methacrylic acid ester of the modified starch The methacrylic acid ester of the modified starch is an ester of at least one selected from the hydroxyl group of the modified starch (a10), methyl methacrylate, ethyl methacrylate, vinyl methacrylate, and 2-ethylhexyl methacrylate. Method (1) obtained by exchange reaction; Method (2) obtained by reacting the hydroxyl group of the modified starch (a10) and methacrylic acid chloride in the presence of the esterification catalyst and the hydroxyl group of the modified starch (a10) It can be obtained by a production method such as a method (3) of esterifying with methacrylic acid.

Modified starch (a10):
Starch which is a starting material of the modified starch (a10) is corn starch, high amylose starch, wheat starch, unmodified starch such as rice starch, rhizome unmodified starch such as potato starch and tapioca starch, dextrin, and decomposition products thereof. Is mentioned.
Here, examples of the starch degradation product include those obtained by subjecting starch to a molecular weight reduction treatment with an enzyme, an acid, or an oxidizing agent. The starch degradation product has a number average molecular weight of 1,000 to 2,000,000, preferably 3,000 to 500,000, more preferably 3,000 to 200,000. It is preferable from the viewpoint of sex.
In the modified starch (a10), an organic functional group such as an aliphatic saturated hydrocarbon group, an aliphatic unsaturated hydrocarbon group or an aromatic hydrocarbon group is added to the starch or starch degradation product via an ester bond and / or an ether bond. It is a modified starch formed by bonding. The modified starch can be used alone or in combination.

  In this specification, the number average molecular weight or the weight average molecular weight is 40 according to JIS K0124-83, using four TSK GEL4000HXL, TSK G3000HXL, TSK G2500HXL, and TSK G2000HXL (manufactured by Tosoh Corporation) as 40 The temperature was determined by calculation from a chromatogram obtained with an RI refractometer and a calibration curve in terms of polystyrene, using tetrahydrofuran for GPC as an eluent at a flow rate of 1.0 ml / min at ° C.

  In addition, as a modification | denaturation method in modified starch (a10), esterification modification | denaturation is mentioned, for example, A C2-C18 acyl group is mentioned as a preferable modification group. Modification | denaturation can be performed by using a C2-C18 organic acid individually or in combination of 2 or more types. The degree of modification of the modified starch is preferably in the range of 0.5 to 2.8, and more preferably in the range of 1.0 to 2.5.

Here, the degree of substitution is the average number of hydroxyl groups substituted by a denaturing agent per monosaccharide unit constituting the starch. For example, the degree of substitution 3 is the number of three hydroxyl groups present in the monosaccharide unit constituting the starch. It means that all are substituted by the modifier, and a substitution degree of 1 means that only one of the three hydroxyl groups present in the monosaccharide units constituting the starch is substituted by the modifier.
If the degree of substitution is less than 0.5, the compatibility with the later-described radical polymerizable unsaturated monomer may be insufficient, and the finish of the formed coating film may be insufficient. On the other hand, when the degree of substitution exceeds 2.8, finish may be deteriorated.

Further, the modified starch (a10) has a glass transition point below the starch decomposition temperature (about 350 ° C.), and can be adjusted in degree of modification so as to have thermoplasticity and finish. desirable. Therefore, when the number of carbon atoms of the substituent used for modification is large, for example, when the substituent is a stearyl group having 18 carbon atoms, the low modification level, for example, the degree of ester substitution is 0.1 to 1.8. It is preferable to be within the range.
Further, when the number of carbon atoms of the substituent is small (the substituent is an acetyl group having 2 carbon atoms), the high modification level, for example, the degree of ester substitution is in the range of 1.5 to 2.8. It is preferable to do.

  As an example of the modified starch (a10), biodegradability obtained by mixing starch having an amylose content of 50% or more with an esterification reagent in an aprotic solvent and reacting the starch and the esterification reagent. Hydrophobic starch ester products (see JP-A-8-502552), starch esters modified with vinyl esters (eg, vinyl acetate, vinyl propionate, vinyl butanoate, etc.) as esterification reagents. As the vinyl ester, a starch ester obtained by reacting with starch using an esterification catalyst in a non-aqueous organic solvent using an ester group having 2 to 18 carbon atoms (JP-A-8-188601) And starch in which polyvinyl ester is grafted together with esterification (JP-A-8-239402 and JP-A-8-3). 1994), a polyester graft polymerized starch having a polyester graft chain on the starch molecule, and a part or all of the hydroxyl groups of the starch chain end and starch directly bonded are blocked by an ester group, and the polyester graft chain Examples include polyester graft polymerized starch alloys (see Japanese Patent Application Laid-Open No. 9-31308) and the like, which are uniformly mixed with an independent polyester having the same constituent components and part or all of the terminal hydroxyl groups blocked by ester groups. Can do.

  Further, a short-long chain mixed starch ester obtained by substituting the hydrogen of the reactive hydroxyl group of the same starch molecule with a short-chain acyl group having 2 to 4 carbon atoms and a long-chain acyl group having 6 to 18 carbon atoms (Japanese Patent Application Laid-Open No. 2000-2000) No. -159801), a short chain-long chain mixture in which the reactive hydroxyl group of the same starch molecule is substituted with a short chain hydrocarbon-containing group having 2 to 4 carbon atoms and a long chain hydrocarbon-containing group having 6 to 24 carbon atoms And starch-substituted derivatives (see JP 2000-159802 A). Since these modified starches are based on starch, they are derived from plants, and are excellent in solvent solubility and compatibility.

[Photocurable paint (A)]
The photocurable paint (A) used in the coating film forming method of the present invention is a paint containing a modified starch (a10) methacrylate (a1) and a photopolymerizable initiator (a2). Furthermore, it is preferable to contain a photocurable compound (a3) in the photocurable coating material (A) for the purpose of improving the coating film performance.

Modified starch methacrylate (a1):
The modified starch used for the modified starch methacrylate (a1) can be the same modified starch as the modified starch (a10).

  The production of the modified starch methacrylic acid ester (a1) is based on the total solid mass of methacrylic acid or methacrylic acid ester (for example, methyl methacrylate) after dissolving the modified starch (a10) in a solvent. Modified starch (a10) in an amount of 50 to 99% by weight, preferably 60 to 98% by weight, and methacrylic acid or methacrylic acid ester in an amount of 1 to 50% by weight, preferably 2 to 40% by weight. For example, hydrocarbon solvents such as toluene, xylene, cyclohexane, n-hexane; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone; or a mixture thereof, etc. Add basic compound and stir at a temperature of about 60-100 ° C., more preferably 70-90 ° C. 30 minutes to 10 hours, more preferably it is possible to obtain about 1 to 5 hours, the esterification or transesterification, methacrylic acid esters of modified starch (a1).

In addition, the production of methacrylic acid ester (a1) of modified starch involves dissolving the modified starch in an organic solvent, adding a methacrylic acid halide (for example, methacrylic acid chloride), neutralizing the acid to be produced, and washing with water. (By dehydrochlorination method).
The weight average molecular weight of the methacrylic acid ester (a1) of the modified starch thus obtained is 3000 to 200,000, preferably 4000 to 100,000, and the hydroxyl value is 0 to 300 mgKOH / g, preferably 5 to 200 mgKOH / It is preferable also from the surface of resin manufacture to have g.

  In addition, in this specification, the number average molecular weight or the weight average molecular weight was determined according to JIS K 0124-83. Using gel filtration chromatography, four separations of “TSKGEL4000HXL”, “G3000HXL”, “G2500HXL”, and “G2000HXL” (manufactured by Tosoh Corporation) are used at 40 ° C. and a flow rate of 1.0 ml / min. Using GPC tetrahydrofuran, the chromatogram obtained with an RI refractometer and the standard polystyrene calibration curve were used.

Photopolymerization initiator (a2):
A photoinitiator (a2) is a compound which carries out radical polymerization of the polymerizable unsaturated group which the methacrylic acid ester (a1) of modified starch has, and hardens a photocurable coating material (A).

  Specific examples of the photopolymerization initiator (a2) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and benzyl. Dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone 2,4,6-trimethylbenzoylphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, benzophenone, methyl o-benzoylbenzoate, hydroxybenzophenone, 2-isopro Ruthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis ( And trichloro) -S-triazine and 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine. These photopolymerizable initiators (a2) can be used alone or in combination of two or more. The content of the photopolymerizable initiator (a2) is in the range of 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the modified starch methacrylate (a1). .

  A photosensitizer may be used in combination with the photopolymerizable initiator (a2) in order to promote the photopolymerization reaction. Examples of photosensitizers that can be used in combination include triethylamine, triethanolamine, methyldiethanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, benzoic acid (2 -Dimethylamino) ethyl, Michler's ketone, tertiary amines such as 4,4'-diethylaminobenzophenone, alkylphosphine such as triphenylphosphine, and thioethers such as β-thiodiglycol. These photosensitization accelerators are preferably in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the modified starch methacrylate (a1).

Photocurable compound (a3):
The photocurable compound (a3) is at least selected from the group consisting of a radically polymerizable unsaturated monomer, a radically polymerizable unsaturated group-containing resin, and a resin that uses a radically polymerizable unsaturated group and a thermosetting functional group in combination. One monomer and / or resin is preferred.
Examples of the radical polymerizable unsaturated monomer include a bifunctional polymerizable monomer, a trifunctional or higher functional polymerizable monomer, and a monofunctional polymerizable monomer.

  Examples of the bifunctional polymerizable monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and polypropylene. Glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate Bisphenol A propylene oxide modified di (meth) acrylate, 2-hydroxy 1-acryloxy-3-methacryloxypropane, tricyclodecane dimethanol di (me ) Acrylate, di (meth) acryloyloxyethyl acid phosphate, and the like. In addition, as bifunctional polymerizable monomers, monomers marketed by Nippon Kayaku Co., Ltd. under trade names such as “Kayarad HX-220”, “Kayarad 620”, “Kayarad R-604”, and “MANDA”. Can also be used.

  Examples of the tri- or more functional polymerizable monomer include trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, trimethylolpropane propylene oxide modified tri (meth) acrylate, and glycerin tri (meth) acrylate. , Glycerin ethylene oxide modified tri (meth) acrylate, glycerin propylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, isocyanuric acid ethylene oxide modified triacrylate, dipentaerythritol hexa ( And (meth) acrylate.

Monofunctional polymerizable monomers that can be used in combination include styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, Cyclohexenyl (meth) acrylate, 2-hydroxyl (meth) acrylate, hydroxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, ε-caprolactone modified tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxy Polyethylene glycol (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) ) Acrylate, benzyl (meth) acrylate, ε-caprolactone-modified hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2 -Hydroxy-3-butoxypropyl (meth) acrylate, monohydroxyethyl (meth) acrylate phthalate, paracumylphenol ethylene oxide modified (meth) acrylate, N-methylol (meth) acrylamide, N-methylol (meth) acrylamide butyl ether, Examples include acryloylmorpholine, dimethylaminoethyl (meth) acrylate, and N-vinyl-2-pyrrolidone.
As the radically polymerizable unsaturated monomer, it is preferable to use a bifunctional or higher functional polymerizable monomer in view of curability, adhesion, scratch resistance and the like.

  The radical polymerizable unsaturated group-containing resin is a resin containing two or more radical polymerizable unsaturated groups in one molecule. For example, unsaturated acrylic resin, unsaturated urethane resin, unsaturated epoxy resin, polyester ( Examples thereof include (meth) acrylate, unsaturated silicone resin, urethane acrylate, epoxy acrylate, polyester acrylate, and the like, and one or two or more selected from these can be used.

  The radical polymerizable unsaturated group and thermosetting functional group-containing resin described here is a resin having one or more radical polymerizable unsaturated groups and one or more thermosetting functional groups in one molecule. From the viewpoint of curability of the coating film, it is preferable to have a plurality of the unsaturated group and the functional group. As the thermosetting functional group, a functional group such as a hydroxyl group, an acid group, an epoxy group, or an isocyanate group can be used. Examples of the acid group include a carboxyl group and a phosphate group.

Specific examples of the radical polymerizable unsaturated group and thermosetting functional group-containing resin described herein include, for example, radical polymerizable unsaturated group-containing acrylic resin, radical polymerizable unsaturated group and epoxy group-containing acrylic resin, radical polymerization An unsaturated resin containing an unsaturated group and an isocyanate group, a radically polymerizable unsaturated group-containing polyester resin, a radically polymerizable unsaturated group-containing epoxy group-containing cresol novolak type epoxy resin, and the like.
Moreover, when a photocurable compound (a3) has a thermosetting functional group, an amino resin, a polyisocyanate compound, an epoxy group containing compound, etc. can be used together, for example. As said amino resin, a melamine resin, a guanamine resin, a urea resin etc. can be used, for example.

  As a blending ratio of the photocurable compound (a3) to the methacrylic ester (a1) of the modified starch, the photocurable compound (a3) is 0 to 900 with respect to 100 parts by mass of the methacrylic ester (a1) of the modified starch. It is preferably from 50 parts by weight, preferably from 50 to 400 parts by weight, in terms of finish and scratch resistance.

  Furthermore, the photo-curable paint (A) may include a crosslinking agent such as a polyisocyanate compound, a matting material, and a surface shape adjusting material, as necessary, to such an extent that the coating film formed by the starch-based colored base paint as a base can be recognized. Surface energy adjusting agents, hardness adjusting agents, ultraviolet absorbers, light stabilizers, antifoaming agents, organic colorants, natural dyes, inorganic pigments, and the like can be used. Use of a polyisocyanate compound in combination is preferable for improving the coating film hardness.

  Examples of the organic colorant include those specified in Ordinance No. 37 of the Ministry of Health and Welfare. For example, Red 202 (Risor Rubin BCA), Red 203 (Rake Red C), Red 204 (Rake Red CBA), Red 205 (Risor Red), Red 206 (Risor Red CA), Red 207 (Risole) Red BA), Red 208 (Risor Red SR), Red 219 (Brilliant Lake Red R), Red 220 (Deep Maroon), Red 221 (Toluidine Red), Red 228 (Parmaton Red), orange No. 203 (Permanent Orange), Orange No. 204 (Bench Gin Orange G), Yellow 205 (Bench Gin Yellow G), Red No. 404 (Brilliant Fast Scarlet), Red No. 405 (Permanent Red F5R), Orange No. 401 ( Hansa Orange), Yellow No. 401 ( Nzaero), and the like Blue No. 404 (phthalocyanine blue).

  Specific examples of natural pigments include carotene, carotenal, capsanthin, lycopene, bixin, crocin, canthaxanthin, anato, etc. Chalcones such as safflower, flavonols such as rutin and quercetin, flavones such as cocoa pigment, flavin, riboflavin, quinone, lacaic acid, carminic acid (cochineal), kermesic acid, Anthraquinones such as alizarin, naphthoquinones such as shikonin, alkanine, echinochrome, polyphyllin, chlorophyll, hemoglobin, diketone, curcumin (turmeric) In the Betashianijin system, like betanin.

  Inorganic pigments include silicic anhydride, magnesium silicate, talc, kaolin, bentonite, mica, titanium mica, bismuth oxychloride, zirconium oxide, magnesium oxide, zinc oxide, titanium oxide, light calcium carbonate, heavy calcium carbonate, light Examples include magnesium carbonate, heavy magnesium carbonate, barium sulfate, yellow iron oxide, bengara, black iron oxide, gunjou, chromium oxide, chromium hydroxide, carbon black, and calamine. What is necessary is just to determine suitably the mixture ratio of an organic pigment, a natural pigment | dye, and an inorganic pigment according to the use used and the performance requested | required.

[Starch-based colored base paint]
The starch-based colored base paint is coated on the base of the photo-curable paint (A), and the coating film of the starch-based colored base paint can be recognized, so that the obtained multilayer coating film exhibits an unprecedented design. It is. For the starch-based colored base paint used in the present invention, it is preferable to use at least one of the following starch-based resin (1), starch-based resin (2) and starch-based resin (3).
Starch-based resin (1)
The starch-based resin (1) is obtained by reacting the modified starch (a10) with the product (I) having an isocyanate group obtained by reacting the polyisocyanate compound (a11) and the polyhydric alcohol (a12). The resulting resin.

Modified starch (a10)
Modified starch (a10) similar to modified starch (a10) described in methacrylic ester (a1) of modified starch can be used.

Products having isocyanate groups (I)
The product (I) having an isocyanate group can be obtained by reacting the polyisocyanate compound (a11) with the polyhydric alcohol (a12).

  Examples of the polyisocyanate compound (a11) include isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, tris (phenylisocyanate) thiophosphate, phenylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene. Diisocyanate, lysine diisocyanate, xylylene diisocyanate, bis (isocyanatomethyl) cyclohexane, bis (isocyanato) methylcyclohexane, dicyclohexylmethane diisocyanate, isopropylidenebis (cyclohexyl isocyanate), 3- (2'-isocyanatocyclohexyl) propylisocyanate And dianisidine diisocyanate, diphenyl ether diisocyanate and the like. Among these, isophorone diisocyanate and hexamethylene diisocyanate are preferably used from the viewpoints of hardness, adhesion, and impact resistance.

  Examples of commercially available products of the polyisocyanate compound (a11) include “Bernock D-750, -800, DN-950, -970 or 15-455” (above, Dainippon Ink and Chemicals, Inc.), “Desmodur. "L, N, HL, or N3390" (product of Bayer, Germany), "Takenate D-102, Takenate D-170HN, Takenate D-202, Takenate D-110 or Takenate D-123N" (Takeda Pharmaceutical Co., Ltd.) Product), “Coronate EH, L, HL or 203” (Nippon Polyurethane Industry Co., Ltd. product) or “Duranate 24A-90CX” (Asahi Kasei Chemicals Co., Ltd. product).

  Specific examples of the polyhydric alcohol (a12) include alkylene diols, trivalent or higher alkylene triols, ether polyols and polyester polyols, acrylic polyols and other polyols.

  Examples of the alkylene diol include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and cyclohexane-1,4. -Diols such as dimethylol, neopentyl glycol, methylpentanediol, hydrogenated bisphenol A;

Examples of the trihydric or higher alkylene polyol include triols such as glycerin, trimethylolethane, and trimethylolpropane; and tetrahydric or higher alkylene polyols such as pentaerythritol, α-methylglycoside, and sorbitol.
As the ether polyol, for example, polyethylene glycol, polypropylene glycol produced by a ring-opening addition reaction of alkylene oxide (specifically, ethylene oxide, diethylene glycol, propylene oxide, dipropylene glycol, butylene oxide, tetrahydrofuran, etc.) Hexols such as polytetramethylene glycol, triethylene glycol, poly (oxyethylene / oxypropylene) glycol, bisphenol A polyethylene glycol ether, bisphenol A polypropylene glycol ether, sucrose, dipentaerythritol, and the like.

  Examples of the polyester polyol include those obtained by a polycondensation reaction between an organic dicarboxylic acid or an anhydride thereof and an organic diol component under an excess of organic diol. Specific examples thereof include a polyester polyol which is a condensate of adipic acid and ethylene glycol and a condensate of adipic acid and neopentyl glycol.

  The organic dicarboxylic acid used here is an aliphatic, alicyclic or aromatic dicarboxylic acid having 2 to 44 carbon atoms, particularly 4 to 36, such as succinic acid, adipic acid, azelaic acid, sebacic acid. Maleic acid, fumaric acid, glutaric acid, hexachloroheptanedicarboxylic acid, cyclohexanedicarboxylic acid, o-phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrachlorophthalic acid and the like. In addition to these dicarboxylic acids, a small amount of polycarboxylic acid anhydrides or unsaturated fatty acid adducts having three or more carboxyl groups can be used in combination. Examples of the organic diol component include ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and other alkylene glycols, dimethylolcyclohexane, butylethylpentyl glycol, and the like. In some cases, these may be used in combination with a small amount of a tri- or higher-valent polyol such as trimethylolpropane, glycerin, or pentaerythritol.

  Of the polyhydric alcohols (a12) described above, in particular, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, hydrogenated bisphenol A, glycerin, trimethylol. Selected from the group consisting of ethane, trimethylolpropane, pentaerythritol, dipentaerythritol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (oxyethylene / oxypropylene) glycol, bisphenol A ethylene glycol ether, bisphenol A polypropylene glycol ether Are also suitable for impact resistance and bending resistance.

  The reaction of the polyisocyanate compound (a11) and the polyhydric alcohol (a12) is carried out by using an organic solvent (for example, hydrocarbons such as toluene, xylene, cyclohexane, n-hexane; esters such as methyl acetate, ethyl acetate, butyl acetate). The reaction ratio of the polyisocyanate compound (a11) and the polyhydric alcohol (a12) in a ketone system such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, or a mixture thereof). The number of moles of OH groups based on polyhydric alcohol (a12) relative to the number of moles of NCO groups based on a11) is NCO groups / OH groups = 1 / 0.4 to 1 / 0.95, preferably 1 / 0.0 5 to 1 / 0.9, so that free isocyanate remains, polyisocyanate The compound (a11) and the polyhydric alcohol (a12) are mixed, and, for example, a catalyst such as monobutyltin oxide or dibutyltin oxide is appropriately added, and the mixture is stirred at 50 ° C. to 200 ° C., preferably 60 to 150 ° C. A product (I) solution having an isocyanate group can be produced by reacting at a temperature of about 0 C for 30 minutes to 10 hours, preferably about 1 to 5 hours. The NCO value of the obtained product (I) having an isocyanate group is preferably in the range of 5 to 250 mg NCO / g, particularly 7 to 200 mg NCO / g.

  Here, the blending ratio of the modified starch (a10) and the product (I) having an isocyanate group can be appropriately adjusted according to the required coating film performance. Preferably, the modified starch (a10) is 50 to 99 mass%, preferably 60 to 98 mass%, based on the total solid mass of the starch and / or modified starch (a10) and the product (I) having an isocyanate group. % And the product (I) having an isocyanate group in an amount in the range of 1 to 50% by weight, preferably 2 to 40% by weight, organic solvents such as toluene, xylene, cyclohexane, n-hexane and other hydrocarbon systems Solvents; ester solvents such as methyl acetate, ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and methyl amyl ketone; or a mixture thereof, etc. A catalyst such as dibutyl tin oxide is added, and is stirred at about 50 ° C. to 200 ° C., more preferably 60 to 150 ° C. At a temperature, it can be obtained 10 hours 30 minutes, more preferably about 1 to 5 hours, starch-based resin by addition reaction of (1).

Here, the blending ratio of the modified starch (a10) and the product (I) having an isocyanate group is within the above range, and it is finished, pencil hardness, scratch resistance, adhesion, alkali resistance and solvent resistance. It is also preferable for obtaining a coating film having a good balance in properties.
It is suitable for the present invention that the number average molecular weight of the starch-based resin (1) obtained by the reaction is in the range of 3,000 to 200,000, preferably 5,000 to 100,000. The resin composition thus produced can be suitably used as a binder for starch-based paints that are dissolved or dispersed in an organic solvent-based solvent.

Starch-based resin (2)
The starch-based resin (2) is obtained by converting a modified starch (a10), a polyisocyanate compound (a11), and a product (I) having an isocyanate group obtained by reacting a polyhydric alcohol (a12) with a vinyl copolymer. This resin is obtained by reacting the resin (a13).
As the modified starch (a10), the same modified starch as the modified starch (a10) described in the unsaturated group-containing starch-based compound can be used.

  As the product (I), the same compounds as those mentioned for the starch-based resin (1) can be used. The vinyl copolymer resin (a13) can be obtained by subjecting a mixture of radically polymerizable unsaturated monomers to a radical polymerization reaction in the presence of an organic solvent and a polymerization initiator.

  The mixture of the radical polymerizable unsaturated monomers is 1 to 90% by weight, preferably 5 to 80% by weight, more preferably 10 to 85% by weight based on the total weight of the mixture. % By weight, hydroxyl group-containing radically polymerizable unsaturated monomer 1 to 50% by weight, preferably 2 to 40% by weight, more preferably 5 to 30% by weight and other radically polymerizable unsaturated monomers 0 to 98% by weight, preferably A coating film excellent in finish, adhesion, scratch resistance, solvent resistance and weather resistance, being a mixture of radically polymerizable unsaturated monomers comprising 2 to 95% by mass, more preferably 5 to 90% by mass Can be formed.

  Examples of the aromatic radical polymerizable unsaturated monomer include styrene, vinyl toluene, 2-methyl styrene, t-butyl styrene, chlorostyrene, vinyl naphthalene, and the like.

  Hydroxyl group-containing radical polymerizable unsaturated monomers include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, methacrylic acid. Hydroxyalkyl esters of acrylic acid or methacrylic acid having 2 to 8 carbon atoms in the alkyl group, such as 2-hydroxypropyl acid and 3-hydroxypropyl methacrylate, and (meth) acrylic acid hydroxyalkyl ester lactone modified products (Daicel Chemistry) Product name “PLAXEL F” series) manufactured by the corporation. Among these, modified starch (a10) contains at least one selected from 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and 4-hydroxybutyl acrylate. And from the viewpoint of improving the compatibility with the product (I) having an isocyanate group and ensuring the stability of the paint.

  Other radical polymerizable unsaturated monomers include carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid, itaconic acid, fumaric acid, such as methyl acrylate, ethyl acrylate, acrylic N-propyl acid, isopropyl acrylate, n-, i- or t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, lauryl acrylate, cyclohexyl acrylate, methacryl Acid methyl, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-, i- or t-butyl methacrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate C1-C18 alkyl ester or cycloalkyl ester of acrylic acid or methacrylic acid such as N; methyl-acrylamide, N-butoxymethylacrylamide, N-methoxymethylacrylamide, N-methylolmethacrylamide, N-butoxymethylmethacrylate Mention may be made of N-substituted acrylamide-based or N-substituted methacrylamide-based monomers such as amides, and these polymerizable unsaturated monomers may also include fatty acid-modified polymerizable unsaturated monomers.

  The fatty acid-modified polymerizable unsaturated monomer includes a polymerizable unsaturated monomer having a polymerizable unsaturated group at the end of a fatty acid-derived hydrocarbon chain. Examples of the fatty acid-modified polymerizable unsaturated monomer include those obtained by reacting a fatty acid with an epoxy group-containing polymerizable unsaturated monomer or a hydroxyl group-containing polymerizable unsaturated monomer.

Examples of fatty acids include dry oil fatty acids, semi-dry oil fatty acids and non-dry oil fatty acids. Examples of dry oil fatty acids and semi-dry oil fatty acids include fish oil fatty acids, dehydrated castor oil fatty acids, safflower oil fatty acids, and linseed oil fatty acids. , Soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hemp oil fatty acid, grape kernel oil fatty acid, corn oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, walnut oil fatty acid, rubber seed oil fatty acid, hygiene Examples include acid fatty acids, and non-drying oil fatty acids include, for example, coconut oil fatty acids, hydrogenated coconut oil fatty acids, and palm oil fatty acids. These can be used alone or in combination of two or more. Furthermore, these fatty acids can be used in combination with caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and the like.

  As the monomer that can be reacted with the above fatty acid in order to produce a fatty acid-modified polymerizable unsaturated monomer, a polymerizable unsaturated monomer containing an epoxy group is suitable, for example, glycidyl (meth) acrylate, β-methylglycidyl. Examples include (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether.

  The vinyl copolymer resin (a13) can be easily prepared, for example, by subjecting a mixture of the above-mentioned radical polymerizable unsaturated monomers to a radical polymerization reaction in an organic solvent in the presence of a polymerization initiator. The mixture of the radically polymerizable unsaturated monomer and the mixture of the polymerization initiator are uniformly added dropwise, for example, at a reaction temperature of 60 to 200 ° C., preferably 80 to 180 ° C., for about 30 minutes to 6 hours, preferably 1 The desired product can be obtained by reacting for ~ 5 hours.

Examples of the organic solvent include hydrocarbon solvents such as toluene, xylene, cyclohexane, and n-hexane; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. A ketone solvent; or a mixture thereof.

  The obtained vinyl copolymer resin (a13) preferably has a hydroxyl value of 5 to 400 mgKOH / g and a weight average molecular weight of 3,000 to 100,000, particularly 5,000 to 20,000. . The vinyl copolymer resin (a13) produced as described above can be used after being dissolved or dispersed in an organic solvent solvent.

  The starch-based resin (2) comprises a modified starch (a10), a product (I) having an isocyanate group obtained by reacting a polyisocyanate compound (a11) and a polyhydric alcohol (a12), and a vinyl copolymer. It is a resin obtained by reacting the resin (a13). Here, the blending ratio of the modified starch (a10), the product (I) having an isocyanate group, and the vinyl copolymer resin (a13) can be appropriately adjusted according to the required coating film performance. .

  Based on the total solid content weight of the modified starch (a10), the product (I) having an isocyanate group and the vinyl copolymer resin (a13), the modified starch (a10) is 60 to 99% by mass, more preferably 65%. ~ 95% by mass, the product (I) having an isocyanate group is 1 to 39% by mass, more preferably 2 to 33% by mass and the vinyl copolymer resin (a13) is 1 to 39% by mass, more preferably 2 to 2%. Mix in an organic solvent similar to that described above for the production of the starch-based resin (1) in an amount in the range of 33% by mass, add a tin catalyst such as monobutyltin oxide, dibutyltin oxide, etc. The starch-based resin (2) is obtained by reacting at a temperature of about 50 ° C. to about 200 ° C., more preferably about 60 to 150 ° C., for 30 minutes to 10 hours, more preferably about 1 to 5 hours. Door can be.

  The blending ratio of the modified starch (a10), the product (I) having an isocyanate group and the vinyl copolymer resin (a13) is within the above range, and the finish, pencil hardness, scratch resistance, adhesion, It is also preferable for obtaining a coating film having a good balance between alkali resistance and solvent resistance. It is suitable for the present invention that the number average molecular weight of the starch-based resin (2) obtained by the reaction is in the range of 3,000 to 200,000, preferably 5,000 to 100,000. The starch-based resin (2) thus produced can be suitably used by dissolving or dispersing in an organic solvent-based solvent.

Starch-based resin (3)
The starch-based resin (3) is a resin using a product (II) obtained by binding a vinyl copolymer resin (a13) to the modified starch (a10) by graft polymerization. Further, a resin obtained by reacting the product (II) with the product (I) having an isocyanate group obtained by reacting the polyisocyanate compound (a11) with the polyhydric alcohol (a12) can also be used.

  The modified starch (a10) is the same as the modified starch (a10) mentioned in the starch-based resin (1) or starch-based resin (2), and the vinyl copolymer resin (a13) is graft-polymerized. As a result, the product (II) is produced.

  Conventionally, U.S. Pat. Nos. 3,425,971 and 3,981,100 and JP-A-56-167746 disclose vinyl monomers using cerium salt as a radical polymerization initiation catalyst in water-dispersed or slurry-like starch or modified starch. The graft polymerization of is disclosed. JP-A Nos. 54-120698 and 55-90518 disclose graft polymerization of styrene and acrylic monomers on starch modified with maleic acid, which is a compound containing an unsaturated group. JP-A-8-239402 discloses graft polymerization of (vinyl) esterified starch and vinyl monomer in an organic solvent.

JP-A-55-133472 and JP-A-56-157463 disclose graft polymerization of vinyl monomers onto cellulose acetate butyrate in a solution using a radical initiator. If nitrocellulose acetate is replaced with starch and / or modified starch, it is easy to bind vinyl polymer to modified starch (a10) by graft polymerization.
As mentioned above, some known examples have been described regarding the graft polymerization of the vinyl polymer, but the target starch resin (3) can be produced by these known methods.
Here, the vinyl copolymer resin (a13) is a resin obtained by subjecting a radical polymerizable unsaturated monomer or a mixture thereof to a radical polymerization reaction in the presence of an organic solvent and a polymerization initiator.

  Here, the ratio of the modified starch (a10) and the vinyl copolymer resin (a13) is not particularly limited, but it is preferable to use a mixture of monomers having different properties as the radical polymerizable unsaturated monomer, This is preferable from the viewpoint of forming a coating film excellent in adhesion, scratch resistance, solvent resistance and weather resistance.

  The radically polymerizable unsaturated monomer is 1 to 90% by weight, preferably 5 to 80% by weight of the aromatic radically polymerizable unsaturated monomer, and 1 to 50% of the hydroxyl group-containing radically polymerizable unsaturated monomer based on the total mass of the mixture. It is desirable to be a mixture of radically polymerizable unsaturated monomers consisting of 0 to 98% by weight, preferably 47 to 95% by weight, preferably 2 to 40% by weight and other radically polymerizable unsaturated monomers. In addition, aromatic radically polymerizable unsaturated monomer, hydroxyl group-containing radically polymerizable unsaturated monomer 1 to 50% by mass and other radically polymerizable unsaturated monomers are the radically polymerizable unsaturated monomers listed in the starch-based resin (2). It is the same.

  Graft polymerization of these radically polymerizable unsaturated monomers is easily performed, for example, by dropping a mixture of the above-mentioned radically polymerizable unsaturated monomers and a polymerization initiator into an organic solvent solution of the modified starch and performing a radical polymerization reaction. be able to. A mixture of a radically polymerizable unsaturated monomer and a mixture of a polymerization initiator are uniformly dropped, for example, at a reaction temperature of 60 to 200 ° C., preferably 80 to 180 ° C., for about 30 minutes to 6 hours, preferably 1 to It can be obtained by reacting for 5 hours.

  Here, as a polymerization initiator, a known radical polymerization initiator can be used. However, when a method of dropping a monomer mixture and a polymerization initiator into an organic solvent solution of modified starch and performing graft polymerization is employed, peroxide is used. It is preferable to use a physical initiator. Examples of such peroxide-based initiators include hydroperoxides such as t-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide; Peroxyesters such as oxylaurate, t-butylperoxybenzoate, t-butylperoxydecanoate; peroxy such as 1,5-di-t-butylperoxy-3,3,5-trimethylcyclohexane Ketals; ketone peroxides such as ethyl acetoacetate; and diacyl peroxides such as benzoyl peroxide.

  Examples of the organic solvent include hydrocarbon solvents such as toluene, xylene, cyclohexane and n-hexane; ester solvents such as methyl acetate, ethyl acetate and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone and methyl amyl ketone. Ketone solvents such as, or a mixture thereof. The product (I) having an isocyanate group is the same as the product (I) exemplified in the starch-based resin (1) and the starch-based resin (2).

  The production of the starch-based resin (3) is 50 to 99% by mass, preferably 60%, based on the total solid mass of the product (II) and the product (I) having an isocyanate group. ~ 98% by mass, product (I) having an isocyanate group is used in the range of 1 to 50% by mass, preferably 2 to 40% by mass, and an organic solvent (for example, toluene, xylene, cyclohexane, n-hexane, etc.) Hydrocarbon solvents; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; or a mixture thereof), and monobutyl as appropriate. A catalyst such as tin oxide or dibutyltin oxide is added and stirred at a temperature of about 50 ° C. to about 200 ° C., preferably 60 to 150 ° C., 30 The starch-based resin (3) can be obtained by addition reaction for a period of 10 minutes, preferably 1 to 5 hours.

  The blending ratio of the isocyanate group-containing product (I) and the product (II) is within the above range, and the balance in finish, pencil hardness, scratch resistance, adhesion, alkali resistance and solvent resistance is balanced. It is also preferable for obtaining a removed coating film.

  The starch-based resin (3) obtained by the reaction preferably has a number average molecular weight in the range of 3,000 to 2,000,000 and in the range of 5,000 to 100,000. is there. The starch-based resin (1), starch-based resin (2), and starch-based resin (3) described above can be used as a binder component in combination of two or more.

The starch-based colored base paint may be blended with other natural product-derived resins as necessary. Examples of natural-derived resins other than starch-based resins include vegetable fibers (cellulose resins), polyhydroxycarboxylic acids typified by polylactic acid, polycaprolactam, and modified polyvinyl alcohol.
In addition, aliphatic polyesters typified by polycaprolactone are also derived from plants. Besides those listed here, plant-derived resins are known. In the present invention, any natural-derived resin that is soluble in a solvent can be used, and among these, a cellulose-derived resin is preferred.

In the present invention, it was found that by adding a small amount of nitrocellulose and / or cellulose acetate butyrate, the drying property of the coating film when used as a one-pack type lacquer coating is improved and the surface hardness is increased.
In addition, polyhydroxycarboxylic acid, particularly polylactic acid, has an effect of increasing the surface hardness, but the coating film tends to become brittle, and a resin derived from cellulose has a better balance of coating film performance and is easy to use.

As nitrocellulose that can be suitably used for the starch-based colored base paint, industrial nitrified cotton BNC-HIG-2 (trade name, manufactured by France Bergerac NC), industrial nitrified cotton RS1-4 (trade name, Korean CNC), Swancell HM1-4 (trade name, manufactured by Kyosei Yoko Co., Ltd.), Selnova BTH1-4 (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd.), and the like. As cellulose acetate butyrate, CAB381- 0.1, CAB381-0.5, CAB381-2, CAB531-1, CAB551-0.01, CAB551-0.2 (all trade names, manufactured by Eastman Chemical Products) and the like.
Moreover, an organic coloring agent, a natural pigment | dye, and an inorganic pigment can be used for a starch-type coloring base coating material as needed.

Examples of the organic colorant, natural pigment, and inorganic pigment include those exemplified for the photocurable coating (A). The blending ratio of the organic colorant, natural pigment, and inorganic pigment may be appropriately determined according to the intended use and required performance, but is usually 100 parts by weight of the resin component of the starch-based colored base paint. It is 0.001-10 mass parts, Preferably it is the range of 0.01-5 mass parts.
Furthermore, a conventionally known crosslinking agent, for example, a compound exemplified as the polyisocyanate compound (a11), a melamine resin, a guanamine resin, a urea resin, or the like is added to the starch-based colored base paint for the purpose of improving curability. Can do.

  Also, plasticizers, UV stabilizers, metal dryers, fluidity modifiers, anti-repellent agents, anti-sagging agents, antioxidants, matting agents, glossing agents, preservatives, curing accelerators, anti-scratch agents, antifoaming agents An agent or the like can be used.

  The starch-based colored base paint is applied or printed by a coating method such as roller coating, brush coating, dip coating, spray coating (non-electrostatic coating, electrostatic coating, etc.), curtain flow coating, screen printing, letterpress printing, etc. I do.

[About coating film formation method]
The coating film forming method of the present invention is not particularly limited as an object to be coated, and metals, plastics, wood and the like can be used. Among these, the plastic product which provided the designability, hardness, and abrasion resistance can be obtained by forming the multilayer coating film of this invention especially using a to-be-coated article and a plastic. Examples of such plastic include acrylic resin, polyester resin, polyamide resin, polycarbonate resin, ABS resin, polypropylene resin, and polyethylene resin.

  On the object to be coated selected from the above, (Step 1) The starch-based colored base coating is applied to a dry film thickness of 0.1 to 30 μm, preferably 0.5 to 10 μm, more preferably 1 to 5 μm. To do. Next, the coating film after coating is dried at a temperature lower than 100 ° C., preferably 40 ° C. or higher and 90 ° C. or lower for 1 to 40 minutes. Or set at room temperature (less than 40 ° C) for 10 minutes or more. (Step 2) The photocurable paint (A) is applied in a dry film thickness of 0.1 to 30 μm, preferably 1 to 25 μm, more preferably 5 to 20 μm. (Step 3) A multilayer coating film can be obtained by irradiating the coating film with light.

  The starch-based colored base paint and the photo-curable paint (A) can be applied by, for example, spray coating, electrostatic coating, curtain coating, spin coating, dipping or the like. Of these, the spray coating method is preferred.

The solid content concentration of the photocurable coating material (A) in the coating method is not particularly limited as long as it can be applied, but is preferably in the range of 10 to 50% by mass. In order to volatilize the organic solvent remaining in the paint after spray coating, heating is performed at 40 ° C. or higher and 90 ° C. or lower for 1 minute to 40 minutes, or setting is performed at room temperature (less than 40 ° C.) for 10 minutes or longer. It is good.
In addition, the hardening method of the coating film of a photocurable coating material (A) can be formed by hardening a coating film by light irradiation or heating / light irradiation.

The light irradiation may be any of electron beam, ultraviolet light, and visible light. Among these, the ultraviolet light with a wavelength of 150 to 450 nm is suitable. Depending on the type of photopolymerization initiator, an irradiation source having a highly sensitive wavelength can be appropriately selected and used. Examples of the ultraviolet irradiation source include a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a carbon arc, a metal halide lamp, and sunlight. UV irradiation conditions to the coating film is usually integrated light quantity 100~2,000mJ / cm ^2, preferably is suitable range of the 200~1,500mJ / cm ^2. As the irradiation time, the coating film can be cured in about 1 second to 5 minutes.

  The means for heating is not particularly limited, and for example, a drying facility such as a hot air furnace, an electric furnace, or infrared induction heating can be applied. The heating temperature is usually in the range of about 35 to 100 ° C., preferably 40 to 90 ° C., when the object to be coated is plastic. The heating time is not particularly limited, but usually a range of 1 to 30 minutes is preferable. In the case of applying a photocurable coating (A) containing a solvent, it is desirable that the solvent is volatilized by heating or setting after coating and then irradiating with light.

  Articles by the coating film forming method of the present invention are, for example, materials such as electric parts, mobile phones, lighting, electric elements, semiconductors, and vending (for example, paint materials, adhesive materials, printing materials, sheet materials, laminated materials, and molding materials) Material etc.).

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited only to this. “Parts” and “%” are “parts by mass” and “% by mass” unless otherwise specified.

Production Example 1 Modified starch no. 1 (corresponding to modified starch (a10))
25 parts of high amylose corn starch (hydroxyl value 500 mg KOH / g) is suspended in 200 parts of dimethyl sulfoxide (DMSO), heated to 90 ° C. with stirring, and held at that temperature for 20 minutes for gelatinization. To this solution, 20 parts of sodium bicarbonate was added as a catalyst, 17 parts of vinyl laurate was added while maintaining 90 ° C., and reacted at that temperature for 1 hour. Next, 37 parts of vinyl acetate is further added and reacted at 80 ° C. for 1 hour. Thereafter, the reaction solution was poured into tap water, stirred at high speed, pulverized, filtered, dehydrated and dried. 1 was prepared.

Production Example 2 Polyurethane resin solution No. Example 1 (corresponding to product (I))
125 L of toluene and 377 parts of isophorone diisocyanate were charged into a 1 L reaction vessel equipped with a thermometer, a thermostat, a stirrer, a condenser, and a dropping device, and the mixture was stirred and mixed in a nitrogen atmosphere and heated to 80 ° C.
Subsequently, 123 parts of 1,4-butanediol was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was aged at 80 ° C. for 30 minutes to obtain a resin solid content of 80% and a polyurethane resin solution No. 1 was adjusted. The polyurethane resin solution No. The NCO value of the resin solid content of No. 1 was 55 mg NCO / g.

Production Example 3 Polyurethane resin solution No. Production example 2 (corresponding to product (I))
In a 1 L reaction vessel equipped with a thermometer, thermostat, stirrer, condenser and dripping device,
125 parts of toluene and 325 parts of isophorone diisocyanate were charged, stirred and mixed in a nitrogen atmosphere, and heated to 80 ° C. Next, 117 parts of triethylene glycol was added dropwise over 3 hours. After completion of the addition, the mixture was aged at 80 ° C. for 30 minutes to give a polyurethane resin solution No. 80 having a resin solid content of 80%. 2 was adjusted. The polyurethane resin solution No. The NCO value of the resin solid content of 2 was 57 mg NCO / g.

Production Example 4 Acrylic resin solution No. Example 1 (corresponding to vinyl copolymer resin (a13))
In a 1 L reaction vessel equipped with a thermometer, thermostat, stirrer, condenser and dripping device,
333 parts of toluene was charged, stirred and mixed in a nitrogen atmosphere, and heated to 100 ° C. Subsequently, the following “mixture No. 1” solution was added dropwise over 4 hours, and after completion of the addition, the solution was aged at 100 ° C. for 1 hour to obtain an acrylic resin solution No. 1 having a resin solid content of 60%. 1 was obtained. The obtained acrylic resin solution No. The hydroxyl value of 1 resin solids was 86 mgKOH / g.

“Mixture No. 1”
200 parts of styrene
150 parts of methyl methacrylate
50 parts of n-butyl acrylate
100 parts of 2-hydroxyethyl methacrylate
25 parts of 2,2′-azobis-2-methylbutyronitrile.

Production Example 5 Acrylic resin solution No. 2 production examples (for comparative production examples)
In a 1 L reaction vessel equipped with a thermometer, thermostat, stirrer, condenser and dripping device,
333 parts of toluene was charged, stirred and mixed in a nitrogen atmosphere, and heated to 100 ° C. Next, the following “mixture No. 2” solution was added dropwise over 4 hours. After completion of the addition, the mixture was aged at 100 ° C. for 1 hour to obtain an acrylic resin solution No. 2 having a resin solid content of 60%. 2 was obtained. The obtained acrylic resin solution No. The hydroxyl value of the resin solid content of No. 2 was 86 mgKOH / g.

“Mixture No. 2”
350 parts of methyl methacrylate
50 parts of n-butyl acrylate
100 parts of 2-hydroxyethyl methacrylate
25 parts of 2,2′-azobis-2-methylbutyronitrile [Production Example of Starch Resin Solution]
Production Example 6 Starch Resin Solution No. Production Example 1 595 parts of butyl acetate was charged in a 1 L reaction vessel equipped with a thermometer, thermostat, stirrer, cooling tube and cooling tube, and the temperature was raised to 50 ° C. while stirring in a nitrogen atmosphere. Next, modified starch No. 1 obtained in Production Example 1 while maintaining 50 ° C. 1 was charged in a reaction vessel, and the temperature was raised to 100 ° C. Stir until 1 is completely dissolved.
Next, the polyurethane resin solution No. obtained in Production Example 2 was used. 25 parts of 1 was added and stirred until uniform, then 0.02 part of dibutyltin dilaurate was added as a catalyst, and the reaction was carried out at 100 ° C. for 6 hours with stirring in a nitrogen atmosphere. Resin solution no. 1 was obtained. Starch-based resin solution No. The NCO value of 1 resin solids was 0.4 mg NCO / g.

Production Example 7 Production of graft product solution (for starch-based colored base paint)
Into a 1 L reaction vessel equipped with a thermometer, thermostat, stirrer, condenser and dropping device, 466 parts of butyl acetate was charged and heated to 50 ° C. with stirring in a nitrogen atmosphere. Subsequently, the modified starch No. obtained in Production Example 1 was maintained at 50 ° C. 1 was charged into a 160-part reaction vessel, and then heated to 100 ° C., and the modified starch No. 1 charged was charged. Stir until 1 is completely dissolved. Next, a “mixture 1” solution having the following composition was added dropwise over 1 hour. After completion of the addition, the solution was aged at 100 ° C. for 1 hour to obtain a graft product solution having a resin solid content of 30%.

"Mixture 1"
Styrene 28 parts Methyl methacrylate 4 parts n-butyl acrylate 4 parts 2-hydroxyethyl methacrylate 4 parts Parkadox CH-50L (Note 1) 4 parts (Note 1) Parkadox CH-50L: Diacyl peroxide 50% contained Manufactured by Kayaku Akzo Co., Ltd., polymerization initiator Production Example 8 Starch-based resin solution No. 2 production (for starch-based coloring base paint)
125 parts of toluene and 292 parts of hexamethylene diisocyanate were charged into a 1 L reaction vessel equipped with a thermometer, a thermostat, a stirrer, a condenser, and a dropping device, and the mixture was stirred and mixed in a nitrogen atmosphere and heated to 80 ° C. Next, 208 parts of triethylene glycol was added dropwise over 3 hours. After completion of the addition, the mixture was aged at 80 ° C. for 30 minutes to obtain a polyurethane resin solution having a resin solid content of 80%. The NCO value of this polyurethane resin was 58 mg NCO / g.
Next, 41 parts of butyl acetate and 600 parts of the graft product solution obtained in Production Example 7 were charged into another 1 L reaction vessel equipped with a thermometer, a thermostat, a stirrer, and a condenser, and stirred in a nitrogen atmosphere. The temperature was raised to 100 ° C. Next, 25 parts of the polyurethane resin solution obtained in the step (1) was added and stirred until uniform, and then 0.04 part of dibutyltin dilaurate was added as a catalyst and stirred at 100 ° C. for 6 hours while stirring in a nitrogen atmosphere. After the reaction, it was diluted with butyl acetate to a solid content of 25%. Two solutions were obtained.

[Production of starch-based colored base paint]
Production Example 9 Colored base paint Production of Starch Resin Solution No. 1 obtained in Production Example 6 1 400 parts (solid content 100 parts), Alpaste FX-7640NS (note 2) 46 parts (solid content 23 parts), high concrete black (note 3) 3 parts (solid content 3 parts), silicia 446 (note 4) 1.5 parts (1.5 parts of solid content) and 59.5 parts of methyl ethyl ketone were added and mixed well with a stirrer. 1 was obtained.
(Note 2) Alpaste-7640NS: Toyo Aluminum Co., Ltd., trade name, aluminum paste (Note 3) Hikonku Black: Yokohama Chemical Co., Ltd., solvent type paint colorant (Note 4) Silicia 446: Fuji Silysia Chemical Co., Ltd. Made of hydrous amorphous silicon dioxide (matting agent).

Production Example 10 Colored Base Paint Production of Colored Base Paint No. 2 obtained in Production Example 9 1, 5 parts of Takenate D-170HN (Note 5) was added and stirred, and the solid content was adjusted with methyl ethyl ketone. 2 was obtained.

  (Note 5) Takenate D-170HN: Takeda Pharmaceutical Co., Ltd., trade name, an isocyanate form of hexamethylene diisocyanate.

Production Example 11 Colored base paint 3 Starch-based resin solution No. obtained in Production Example 8 2 400 parts (solid content 100 parts), Alpaste FX-7640NS (note 2) 46 parts (solid content 23 parts), high concrete black (note 3) 3 parts (solid content 3 parts), silicia 446 (note 4) 1.5 parts (1.5 parts of solid content) and 59.5 parts of methyl ethyl ketone were added and mixed well with a stirrer. 3 was obtained.

Production Example of Modified Starch Methacrylate (a1) Production Example 12
In a reaction vessel equipped with a thermometer, thermostat, stirrer, condenser and condenser, 25 parts of high amylose corn starch (hydroxyl value 500 mg KOH / g) was suspended in 200 parts of dimethyl sulfoxide (DMSO) and stirred at 90 ° C. The mixture is heated up to 20 minutes and held at that temperature for 20 minutes for gelatinization. To this solution, 20 parts of sodium bicarbonate was added as a catalyst, 17 parts of vinyl laurate was added while maintaining 90 ° C., and reacted at that temperature for 1 hour to obtain a modified starch. Next, 37 parts of vinyl acetate and 2 parts of vinyl methacrylate are added to the reaction vessel and reacted at 80 ° C. for 1 hour. Thereafter, the reaction solution was poured into tap water, stirred at high speed, dissolved and pulverized, filtered, dehydrated and dried to obtain a modified starch methacrylate powder.
Next, 75 parts of butyl acetate was charged into another reaction vessel equipped with a thermometer, thermostat, stirrer, cooling tube and cooling tube, and the temperature was raised to 50 ° C. while stirring in a nitrogen atmosphere. Subsequently, 25 parts of the modified starch methacrylic acid ester powder obtained above was kept in a reaction vessel while maintaining the temperature at 50 ° C., stirred until completely dissolved, and the modified starch methacrylic acid ester having a solid content concentration of 25%. Solution No. 1 was obtained.

Production Example 13
In Production Example 12, a modified starch methacrylic acid ester solution having a solid content concentration of 25% was obtained in the same composition and operation except that the blending part of vinyl methacrylate was changed from 2 parts to 0.5 parts. 2 was obtained.

Production Example 14
In Production Example 12, a modified starch methacrylic acid ester solution No. 1 having a solid content concentration of 25% was prepared by the same blending contents and operation except that the blending part of vinyl methacrylate was 8 parts. 3 was obtained.

Production Example 15
In Production Example 12, a modified starch having a solid content concentration of 25% and a methacrylic acid ester solution No. 4 was obtained.

Production Example 16 Photocurable Compound Solution No. 1 production example (equivalent to photocurable resin (a3))
A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and an air blowing device was charged with 888 parts of isophorone diisocyanate, 464 parts of 2-hydroxyethyl acrylate and 0.7 part of hydroquinone monomethyl ether, and air was introduced into the reaction container. The temperature was raised to 80 ° C. while blowing, and maintained at that temperature for 5 hours. After confirming that all of the added 2-hydroxyethyl acrylate had reacted substantially, 136 parts of pentaerythritol, 372 parts of butyl acetate and dibutyl 0.2 parts of tin dilaurate was added, and the temperature was further maintained at 80 ° C. After confirming that substantially all of isophorone diisocyanate had reacted, the mixture was cooled, and photocurable compound solution No. 80 having a resin solid content of 80% was cooled. 1 was obtained. The number average molecular weight of this resin was about 1,500.

[Production Example of Photocurable Paint (A)]
Production Example 17 Photocurable Paint No. 1 production
Methacrylic acid ester solution No. obtained in Production Example 12 1 part 100 parts (solid content) Irgacure 184 (Note 6) 6 parts, photocurable compound solution No. 1 obtained in Production Example 16. 1 was added and dissolved in 200 parts (solid content), and then diluted with butyl acetate to a solid content concentration of 30%. 1 was obtained.

Production Examples 18 to 24 Photocurable Paint No. 2-No. Production of No. 8 Photocurable paint No. 8 was prepared in the same manner as in Production Example 17 except that the contents of Table 1 were used. 2-No. 8 was obtained.

(Note 7) Irgacure 184: Photo radical polymerization initiator manufactured by Ciba Specialty Chemicals Co., Ltd. Comparative Production Example 1 Production of Acrylic Resin Solution No. 4 obtained in Production Example 5 2 400 parts (solid content 100 parts), Alpaste FX-7640NS (note 2) 46 parts (solid content 23 parts), high concrete black (note 3) 3 parts (solid content 3 parts), silicia 446 (note 4) 1.5 parts (1.5 parts of solid content) and 59.5 parts of methyl ethyl ketone were added and mixed well with a stirrer. 4 was obtained.
Comparative Production Example 2 Photocurable Paint No. No. 9 photocurable compound solution No. obtained in Production Example 16 1 was added to 100 parts (solid content) of 3 parts of Irgacure 184 and dissolved, and then diluted with butyl acetate to a solid content concentration of 30%. 9 was obtained.

[About the test material board]
As a test plate, 2.0 mm × 100 mm × 150 mm of Psycolac Y665C-450 (manufactured by Nippon GE Plastics, trade name, ABS resin) was used.

Example 1
Step 1: After degreasing the test plate with isopropanol, the colored base paint No. obtained in Production Example 9 was used. 1 was applied by air spray so that the dry coating film became 8 μm, and dried at 60 ° C. for 15 minutes.

  Step 2: The photocurable paint No. obtained in Production Example 17 1 was applied by air spray so that the dry coating film became 12 μm, and dried at 60 ° C. for 5 minutes.

Step 3: Photocuring was performed by irradiating 600 mJ / cm ² of ultraviolet light with a high-pressure mercury lamp, and the multilayer coating film No. 1 was formed.

Examples 2-10
A multilayer coating film No. 1 was prepared in the same manner as in Example 1 except that the paints and steps shown in Table 2 were taken. 2-No. 10 was formed.

Comparative Examples 1-3
A multilayer coating film No. 1 was prepared in the same manner as in Example 1 except that the paints and steps shown in Table 3 were taken. 11-No. 13 was formed.

  The multilayer coating film No. 1-No. The test plate having No. 13 was used for the test according to the following test conditions. The results of the examples are shown in Table 2, and the results of the comparative examples are shown in Table 3.

[Test method]
(Note 8) Biological component composition: Each colored base paint and photo-curable paint were evaluated according to the following criteria.

○: Resin obtained by reacting starch-based resin or starch-based resin (bio-derived component) blended in the paint ×: Resin obtained by reacting starch-based resin or starch-based resin ( Those that are not blended in the paint.

  (Note 9) Finishing property: The appearance of each multilayer coating film was visually evaluated.

    A: Good finish.

    ○: Slight undulation but good finish.

    (Triangle | delta): The fall of at least 1 sort (s) of finish of a wave | undulation, glossiness, and Chile skin is seen.

    X: The fall of at least 1 sort of finish of a wave | undulation, glossiness, and Chile skin is remarkable.

(Note 10) Pencil hardness: In accordance with JIS K 5600-5-4 (1999), the pencil core is applied at an angle of about 45 degrees with respect to each multilayer coating surface, and the test coating plate is strong enough to prevent the core from breaking. It was moved about 10 mm forward at a uniform speed while pressing against the surface. The hardness symbol of the hardest pencil when this operation was repeated 5 times while changing the test location and the coating film was not torn was defined as pencil hardness.
(Note 11) Scratch resistance: Each multi-layer coating film surface was judged according to how much scratches were made after pressing a commercially available business card against the coating film and rubbing 20 times.
◎: Not scratched at all ○: Scratch is hardly scratched and scratches are not recognized unless approached (about 5 cm).
Δ: Slightly scratched ×: Scratch is severe.

  (Note 12) Adhesion: On each multi-layer coating film surface, 100 1 mm × 1 mm gobangs were made on the coating film according to JIS K 5600-5-6 (1990), and adhesive tape was applied to that surface. And after peeling off rapidly, the number of the Gobang eyes coating film which remained on the coating surface was evaluated.

○: Remaining number / total number = 100/100 Δ: Remaining number / total number = 99 to 90/100 ×: Remaining number / total number = 89 or less / 100

  (Note 13) Alkali resistance: 0.5 mL of a 1% aqueous sodium hydroxide solution was dropped on each multilayer coating film surface and allowed to stand in an atmosphere at a temperature of 20 ° C. and a relative humidity of 65% for 24 hours. The appearance was wiped off with gauze and visually evaluated.

    ○: No abnormality on the coating film surface.

    (Triangle | delta): Discoloration (whitening) of the coating-film surface is recognized.

    X: Discoloration (whitening) of the coating film surface is remarkable.

(Note 14) Solvent resistance: Two filter papers were placed side by side on each multilayer coating film surface, and 78% ethanol and 2% formalin were dropped onto each filter paper with a dropper to wet the filter paper. The dropping with the dropper was performed 5 times at 1 hour intervals, and the coating film surface excluding the filter paper was visually evaluated after 2 hours.
○: No abnormalities such as bulges and peelings △: Mild abnormalities such as bulges and peelings are found visually: The coating film melts

  Using plant-derived starch, a coated article having excellent finish, pencil hardness, scratch resistance, adhesion, alkali resistance, and solvent resistance can be obtained.

Claims (5)

Apply a starch-based colored base paint containing a starch-based resin on the object to be coated,
Next, a method for forming a coating film, comprising applying a photocurable paint (A) containing a methacrylic acid ester (a1) of a modified starch and a photopolymerization initiator (a2), followed by light irradiation. Furthermore, a photocurable coating material (A) contains a photocurable compound (a3), The coating-film formation method characterized by the above-mentioned. The multilayer coating film obtained by the coating-film formation method of Claim 1 or 2. The coated article which has the multilayer coating film obtained by the coating-film formation method of Claim 1 or 2. The coated article according to claim 4, wherein the article to be coated is plastic.