JP2011208080A - Method for producing composition for water based coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a composition for water based coatings, containing modified starch excellent in water resistance, solvent resistance and mechanical characteristics, wherein the modified starch is stably dispersed and the composition is produced at a low cost, has large contribution to reduce environmental load and is excellent in coating performance.SOLUTION: The method for producing the composition for water based coatings includes a modified starch-generating step for generating the modified starch by substituting a part of hydroxyl groups in the starch with a radically polymerizable functional group. More precisely, the method for producing the composition for water based coatings includes a step for generating a starch derivative-containing water-based emulsion by emulsion polymerization of the modified starch and the radically polymerizable monomer in a water-based solvent.

Description

  The present invention relates to a method for producing a water-based paint composition.

In recent years, water-based coating compositions have been promoted from the viewpoint of environmental problems. Biomass materials are organic resources created by photosynthesis and are resources that can be regenerated continuously. For this reason, substituting biomass materials for limited fossil resources leads to the reduction of carbon dioxide (CO ₂ ) in the atmosphere, and contributes to the prevention of global warming and the formation of an environmental recycling society. One typical biomass material is starch. Starch has a high utility value because of its abundant supply, low cost, excellent processability, and biodegradability.

  From such a viewpoint, it has been proposed to use a water-based emulsion containing a copolymer of highly modified esterified starch (having a high degree of ester substitution) and an acrylic monomer as a water-based paint composition (Patent Documents). 1). The copolymer is excellent in water resistance because it uses a hydrophobized modified starch. However, since advanced esterification of starch requires a reaction in a non-aqueous organic solvent, the aqueous coating composition has a problem that it has a large environmental load and a high cost in the production process of the modified starch. . In the water-based coating composition, the compatibility between the modified starch and the acrylic monomer affects the performance and handling properties. For this reason, in the said composition for water-system coatings, the compounding rate of modified starch is limited.

JP 2006-52338 A

  Therefore, the present invention contains a modified starch excellent in water resistance, solvent resistance and mechanical properties, and the modified starch is stably dispersed at a low cost, greatly contributing to the reduction of environmental burden, and the coating film performance. An object of the present invention is to provide a method for producing a water-based coating composition excellent in water.

In order to achieve the above object, the production method of the present invention is a method for producing a water-based paint composition containing a modified starch,
It includes a modified starch production step of producing a modified starch by substituting a part of hydroxyl groups of starch with a radical polymerizable functional group.

  According to the present invention, by introducing a radically polymerizable functional group into starch to obtain modified starch, it contains modified starch excellent in water resistance, solvent resistance and mechanical properties, and the modified starch is stably dispersed. Thus, it is possible to obtain a water-based coating composition that is low in cost, greatly contributes to reducing the environmental burden, and has excellent coating film performance.

  In the present invention, the “aqueous solvent” means water or a mixed solvent containing water, and is preferably water.

  According to the present invention, there is provided an aqueous coating composition characterized in that it contains a modified starch in which a part of the hydroxyl group of starch is substituted with a radically polymerizable functional group.

  The production method of the present invention may further include a starch derivative-containing aqueous emulsion production step of producing a starch derivative-containing aqueous emulsion by emulsion polymerization of the modified starch and the radical polymerizable monomer in an aqueous solvent. In the aqueous coating composition provided by the present invention, the modified starch may contain an aqueous emulsion of a starch derivative, which is an emulsion polymer of the modified starch and a radical polymerizable monomer.

  In the production method of the present invention, in the modified starch production step, the degree of substitution with the radical polymerizable functional group is in the range of 0.01 to 1 in terms of an average value per sugar residue of the starch. Is preferred. In the water-based coating composition provided by the present invention, the degree of substitution of the modified starch with the radical polymerizable functional group is 0.01 to 1 in terms of an average value per sugar residue of the starch. It is preferable that it is the range of these.

  In the production method of the present invention, in the modified starch production step, an acid anhydride having a radically polymerizable unsaturated group is subjected to ring-opening addition to the starch, whereby a part of the hydroxyl group of the starch is radically polymerizable functional group. May be substituted. In the production method of the present invention, in the modified starch production step, the starch and an acid having a radically polymerizable unsaturated group are subjected to dehydration condensation, whereby a part of the hydroxyl groups of the starch is radically polymerizable functional group. May be substituted.

  In the production method of the present invention, the modified starch production step may be carried out by a dry reaction. In the production method of the present invention, the modified starch production step may be performed by a wet reaction using an aqueous solvent.

  In the production method of the present invention and the aqueous coating composition provided by the present invention, the radical polymerizable functional group is preferably at least one of a maleic acid ester and an itaconic acid ester.

  In the production method of the present invention and the aqueous coating composition provided by the present invention, the modified starch preferably has a weight average molecular weight of 300,000 or less. Thereby, the composition for water-system paints with which dispersion | distribution of the said modified starch was stabilized more can be obtained. The weight average molecular weight of the modified starch is more preferably in the range of 5,000 to 200,000, and still more preferably in the range of 5,000 to 150,000. The weight average molecular weight can be measured by, for example, a gel permeation chromatograph (GPC) method.

  In the production method of the present invention, in the starch derivative-containing aqueous emulsion production step, the weight ratio of the modified starch (A) to the radical polymerizable monomer (B) is A: B = 5: 95 to 50:50. A range is preferable. The ratio (A: B) is more preferably in the range of A: B = 5: 95 to 30:70, more preferably in the range of A: B = 5: 95 to 25:75, especially Preferably, A: B = 10: 90 to 20:80.

  In the production method of the present invention, an emulsifier may be used in the starch derivative-containing aqueous emulsion production step.

  The production method of the present invention may further include a curing agent blending step of blending a curing agent. In addition, the water-based paint composition provided by the present invention may further contain a curing agent. The curing agent is preferably at least one selected from the group consisting of polycarbodiimides, isocyanate compounds, and amino resins.

(1) Method for Producing Water-Based Paint Composition Next, the method for producing the water-based paint composition of the present invention will be described with examples. As described above, the production method of the present invention includes a modified starch production step.

(1-1) Modified starch production step First, starch is prepared. Examples of the starch used in this process include corn starch (corn starch); high amylose corn starch; waxy corn starch; sago starch; mung bean starch; wheat starch; rice starch; potato starch; And modified starch obtained by etherification. The said starch may be used individually by 1 type, and may use 2 or more types together.

  What is necessary is just to set suitably the weight average molecular weight of the said starch according to the weight average molecular weight of the above-mentioned modified starch, and it does not restrict | limit in particular. As a method for adjusting the weight average molecular weight, for example, conventionally known methods such as acid hydrolysis, oxidative decomposition, and enzymatic decomposition can be adopted.

  Next, a modified starch is produced | generated by substituting a part of hydroxyl group of the said starch with a radically polymerizable functional group. The radical polymerizable functional group may be any group as long as it has radical polymerizability. For example, maleic acid ester, itaconic acid ester, acrylic acid ester, methacrylic acid ester, allyl group-containing ester, allyl group Containing ethers, citraconic acid esters, fumaric acid esters, cinnamic acid esters and the like. In consideration of ease of introduction into the starch, cost, and the like, the radical polymerizable functional group is preferably at least one of a maleic acid ester and an itaconic acid ester.

  Next, a method for producing the modified starch will be described with an example.

  The first method for producing the modified starch is a method of ring-opening addition of an acid anhydride having a radical polymerizable unsaturated group to the starch by a wet reaction using an aqueous solvent. The aqueous solvent is not limited to water, and an aqueous solution containing a necessary amount of salt, alcohol, or the like in water may be used as necessary. Specifically, after the starch is suspended in a weak alkaline aqueous solvent, an acid anhydride is added and reacted. Examples of the acid anhydride that can be used in the first method include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like. The said acid anhydride may be used individually by 1 type, and may use 2 or more types together. In this first method, the reaction temperature is preferably in the range of 20 to 80 ° C., and the reaction time is preferably in the range of 20 to 300 minutes.

  Next, the obtained reaction product (modified starch) is washed with water, filtered, and dried.

  The second method for producing the modified starch is a method in which an acid anhydride having a radical polymerizable unsaturated group is ring-opened and added to the starch by a wet reaction using a non-aqueous solvent. Specifically, after the starch is suspended or dissolved in a weak alkaline non-aqueous solvent, an acid anhydride is added and reacted. The acid anhydride that can be used in the second method is the same as in the first method. Examples of the non-aqueous solvent include dimethyl sulfoxide (DMSO), acetone, N, N-dimethylformamide (DMF), methyl ethyl ketone (MEK), N, N-dimethylacetamide (DMAc), pyridine, and the like. The said non-aqueous solvent may be used individually by 1 type, and may use 2 or more types together. In this second method, the reaction temperature is preferably in the range of 20 to 100 ° C., and the reaction time is preferably in the range of 20 to 300 minutes.

  Next, the obtained reaction product (modified starch) is filtered and dried after reprecipitation with ethanol.

  A third method for producing the modified starch is a method of dehydrating and condensing the starch and an acid having a radical polymerizable unsaturated group by a dry reaction. Specifically, the starch and the acid are mixed with powder and subjected to a dry reaction. Examples of the acid that can be used in the third method include maleic acid, itaconic acid, citraconic acid, crotonic acid, fumaric acid, cinnamic acid, acrylic acid, and methacrylic acid. In this third method, the reaction temperature is preferably in the range of 80 to 180 ° C., and the reaction time is preferably in the range of 20 to 300 minutes. This dry reaction is a method in which an acid anhydride having a radically polymerizable unsaturated group is added to the starch by ring-opening addition in addition to or instead of the method of dehydrating and condensing the starch and an acid having a radically polymerizable unsaturated group. There may be. According to the third method, modified starch can be obtained at lower cost.

  You may implement this process by adding a catalyst. Examples of the catalyst include metal hydroxides, mineral acid salts, carbonates, organic compounds or alkali metal alkoxides belonging to the fifth period in the periodic table; organic intercalation catalysts; amino compounds and the like. Examples of metal hydroxides, mineral salts, carbonates, organic compounds or alkali metal alkoxides belonging to the fifth period in the periodic table include alkali metal waters such as sodium hydroxide, potassium hydroxide and lithium hydroxide. Oxides; alkali metal organic acid salts such as sodium acetate and sodium p-toluenesulfonate; alkaline earth metal hydroxides such as barium hydroxide and calcium hydroxide; calcium acetate, calcium propionate and barium p-toluenesulfonate Alkaline earth metal organic acid salts such as sodium phosphate, calcium phosphate, sodium hydrogen sulfite, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, potassium sulfate, sodium aluminate, potassium zincate, etc .; Amphoteric metals such as aluminum hydroxide and zinc hydroxide Oxide and the like. Examples of the organic interlayer transfer catalyst include quaternary ammonium compounds such as trimethylpropylammonium chloride and tetraethylammonium chloride. Examples of the amino compound include dimethylaminopyridine and diethylaminoacetic acid. Among these, from the viewpoint of reaction efficiency and cost, a metal hydroxide, mineral acid salt, carbonate, organic compound, or alkali metal alkoxide belonging to the fifth period in the periodic table is particularly preferable. The said catalyst may be used individually by 1 type, and may use 2 or more types together. In the case of using the catalyst, the timing and method for adding the catalyst are not particularly limited.

  The method for producing the modified starch is not limited to the first to third methods. For example, the starch and the acid having a radical polymerizable unsaturated group are dehydrated and condensed by a wet reaction using a non-aqueous solvent. Any method, such as a method of reacting the starch with an acid halide such as acid chloride or glycidyl ether in a wet reaction or dry reaction using a non-aqueous solvent, a dry reaction performed using an extruder, etc. Also good.

  The weight average molecular weight of the modified starch is as described above.

As described above, in the modified starch production step, the degree of substitution with the radical polymerizable functional group is an average value per sugar residue of the starch and is in the range of 0.01 to 1. The degree of substitution is preferably in the range of 0.02 to 0.8, and more preferably in the range of 0.05 to 0.5. For example, by lowering the degree of substitution to 1 or less, 0.8 or less, or 0.5 or less, etc., (I) For example, the modified starch and radical polymerizable monomer in the starch derivative-containing aqueous emulsion production step described below (II) For example, when the radical polymerizable functional group contains a carboxyl group such as a maleic acid ester, the covalent bond of is not excessive, and a high-performance water-based coating composition can be obtained. (III) The starch content in the modified starch can be increased, and the contribution to reducing environmental burdens such as CO ₂ reduction can be increased. is there.

(2) Starch derivative-containing aqueous emulsion production step As described above, the production method of the present invention further produces a starch derivative-containing aqueous emulsion by emulsion polymerization of the modified starch and the radical polymerizable monomer in an aqueous solvent. You may include the starch derivative containing water-system emulsion production | generation process. Examples of the radical polymerizable monomer include acrylic acid esters, methacrylic acid esters, styrene derivatives, vinyl acetates, acrylamides, methacrylamides, acrylonitriles, and methacrylonitriles.

  Examples of the acrylate esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, Isopentyl acrylate, n-hexyl acrylate, isohexyl acrylate, n-heptyl acrylate, isoheptyl acrylate, 2-ethylhexyl acrylate (2EHA), n-octyl acrylate, isooctyl acrylate, acrylic acid Examples include n-nonyl, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, and benzyl acrylate. Examples of the methacrylic acid esters include methyl methacrylate (MMA), ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate (BMA), isobutyl methacrylate, t-butyl methacrylate, N-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, n-heptyl methacrylate, isoheptyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate , N-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, benzyl methacrylate and the like.

  Examples of the styrene derivative include styrene, α-methylstyrene, methylstyrene, ethylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, and the like.

  Examples of the vinyl acetates include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristylate, vinyl palmitate, vinyl stearate, and cyclohexanecarboxylic acid. Examples thereof include vinyl, vinyl pivalate, vinyl octylate, vinyl monochloroacetate, vinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate and vinyl versatate.

  Examples of the acrylamides include acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, and Nn-. Examples include propoxymethyl acrylamide, Nn-butoxymethyl acrylamide, N-methoxyethyl acrylamide and the like. Examples of the methacrylamides include methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N-methoxymethylmethacrylamide, N-ethoxy. Examples thereof include methyl methacrylamide, Nn-propoxymethyl methacrylamide, Nn-butoxymethyl methacrylamide, N-methoxyethyl methacrylamide and the like.

  Examples of the acrylonitriles include acrylonitrile, α-methylacrylonitrile, α-ethylacrylonitrile, α-methoxymethylacrylonitrile, α-chloromethylacrylonitrile, α-ethoxymethylacrylonitrile, α-butoxymethylacrylonitrile, α-phenoxymethylacrylonitrile, and the like. Is mentioned. Examples of the methacrylonitriles include methacrylonitrile, α-methyl methacrylonitrile, α-ethyl methacrylonitrile, α-methoxymethyl methacrylonitrile, α-chloromethyl methacrylonitrile, α-ethoxymethyl methacrylo. Examples include nitrile, α-butoxymethyl methacrylonitrile, α-phenoxymethyl methacrylonitrile, and the like.

  The radical polymerizable monomer may be used alone or in combination of two or more. In this step, the weight ratio of the modified starch (A) and the radical polymerizable monomer (B) is as described above.

  Next, a method for emulsion polymerization of the modified starch and the radical polymerizable monomer in an aqueous solvent will be described with an example.

  The first method of emulsion polymerization of the modified starch and the radical polymerizable monomer in an aqueous solvent is a method in which the radical polymerizable monomer is dropped into an aqueous solution of the modified starch. Specifically, first, the modified starch is dissolved in water while heating as necessary (for example, at 95 ° C. for 30 minutes). Next, after replacing oxygen in the system with argon gas, an emulsifier and an initiator are added to the aqueous solution of the modified starch. Next, the said radically polymerizable monomer is dripped over 60 to 120 minutes, stirring in an oil bath of 20-90 degreeC. Thereafter, the mixture is further stirred at 20 to 90 ° C. for 60 to 300 minutes to carry out emulsion polymerization.

  Examples of the emulsifier that can be used in the first method include an anionic emulsifier, a nonionic emulsifier, and a reactive emulsifier. Examples of the anionic emulsifier include sulfates of higher alcohols, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, fatty oil sulfates, aliphatic amines or aliphatic amides. Sulfate, dibasic fatty acid sulfonate, aliphatic amide sulfonate, alkyl or alkenyl sulfonate, alkyl benzene sulfonate, alkyl benzene succinate, formalin condensed naphthalene sulfonate, aliphatic alcohol phosphorus Acid ester salts, polyoxyethylene alkyl (phenyl) ether phosphate ester salts and the like can be mentioned. Specific examples include sodium laurate sulfate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium diphenyl ether disulfonate, sodium dialkyl ester sulfonate succinate and the like. Examples of the nonionic emulsifier include polyoxyethylene alkyl ester, polyoxyethylene alkyl aryl ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and the like. Is mentioned. Examples of the reactive emulsifier include reactive emulsifiers having one or more ethylenically unsaturated bonds. The said emulsifier may be used individually by 1 type, and may use 2 or more types together. The addition amount of the emulsifier may be appropriately set according to the type of the emulsifier, the type and composition of the radical polymerizable monomer, and is not particularly limited. It is in the range of 5 to 10% by weight.

  Examples of the initiator that can be used in the first method include potassium persulfate, potassium peroxodisulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, isopropylbenzene hydroperoxide, paramentane hydroperoxide, and benzoyl peroxide. Peroxides such as oxide, di-t-butyl peroxide and dilauroyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobisisovaleronitrile, 2,2′-azobis Azo compounds such as isocapronitrile, 2,2′-azobis (phenylisobutyronitrile), 2,2′-azobis (2-amidinopropane) dihydrochloride; dicesium ammonium sulfate; redox initiators, etc. Can be mentioned. Examples of the reducing agent in the redox initiator include sodium thiosulfate, sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, ammonium ferrous sulfate, glucose, sodium formaldehyde sulfoxylate, L-ascorbic acid and salts thereof. Etc. One kind of the initiator may be used alone, or two or more kinds may be used in combination. Although the addition amount of the initiator is not particularly limited, for example, it is in the range of 0.03 to 3% by weight with respect to the total amount of the radical polymerizable monomer.

  In this step, a conventionally known additive may be added in addition to the emulsifier and the initiator. Examples of the additive include a polymerization accelerator, a chain transfer agent, a water-soluble polymer compound, various emulsions such as acrylic acid or methacrylic acid, an antifoaming agent, an antiseptic, an antifungal agent, a leveling agent, and a film forming agent. Auxiliaries, anti-aging agents, ultraviolet absorbers, dyes, pigments, antifreezing agents and the like can be mentioned. In the case of using the additive, the timing and method for adding the additive are not particularly limited.

  In the second method of emulsion-polymerizing the modified starch and the radical polymerizable monomer in an aqueous solvent, a part of the aqueous solution of the modified starch containing the radical polymerizable monomer part or all of an emulsifier and an initiator, or This is a method in which a pre-emulsion is added dropwise to the remainder of the aqueous solution of the modified starch containing an emulsifier and an initiator, or into water. Except for this, the second method is the same as the first method.

  The method of emulsion polymerization of the modified starch and the radical polymerizable monomer in an aqueous solvent is not limited to the first and second methods. For example, an aqueous solution of the modified starch is added to an emulsifier. Alternatively, any method such as a method of emulsifying using a high-pressure emulsifier, an ultrasonic emulsifier, a high-pressure colloid mill, a high-pressure homogenizer, a high-speed stirrer, or the like may be used.

  The modified starch generation step and the starch derivative-containing aqueous emulsion generation step may be performed continuously in the same apparatus or may be performed using different apparatuses.

(3) Curing agent blending step As described above, the production method of the present invention may further include a curing agent blending step of blending a curing agent. This step may be performed simultaneously with at least one of the modified starch generation step and the starch derivative-containing aqueous emulsion generation step, or may be performed as a separate independent step. In addition, when this step is carried out as a separate independent step, its implementation time is not particularly limited, and for example, it may be carried out between the modified starch production step and the starch derivative-containing aqueous emulsion production step, You may implement after the said starch derivative containing water-system emulsion production | generation process.

  The curing agent is not particularly limited, and for example, it reacts complementarily with the functional group introduced in at least one of the modified starch production step and the starch derivative-containing aqueous emulsion production step or the residual hydroxyl group of the starch. Examples thereof include those having a functional group (for example, carbodiimide group, isocyanate group, acid anhydride group, acid group, amino group, amide group, imino group, etc.). Specifically, for example, polycarbodiimide, an isocyanate compound, an amino resin, or the like can be used.

  The polycarbodiimide is a polymer having a carbodiimide group (—N═C═N—) in the molecule, and is commercially available from Nisshinbo Chemical Co., Ltd. as a registered trademark “carbodilite”.

  The isocyanate compound may be an isocyanate compound having a free isocyanate group or an isocyanate compound having a blocked isocyanate group. Examples of the isocyanate compound having a free isocyanate group include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; cyclic aliphatic diisocyanates such as xylene diisocyanate and isophorone diisocyanate; tolylene diisocyanate, 4,4 ′. -Aromatic diisocyanates such as diphenylmethane diisocyanate; derivatives and polymers thereof. As the isocyanate compound having a free isocyanate group, for example, a commercially available product may be used. Examples of the commercially available products include trade names “Bernock D-750, -800, DN-950, -970, 15-455” manufactured by Dainippon Ink & Chemicals, Inc., trade names “Dismodule” manufactured by Bayer. "L, N, HL, N3390", trade names "Takenate D-102, -202, -110, -123N" manufactured by Takeda Pharmaceutical Co., Ltd., trade names "Coronate EH, L" manufactured by Nippon Polyurethane Industry Co., Ltd. HL, 203 ", trade name" Duranate 24A-90CX "manufactured by Asahi Kasei Corporation. As the isocyanate compound having a blocked isocyanate group, for example, the isocyanate compound having a free isocyanate group was blocked with a conventionally known blocking agent such as oxime, phenol, alcohol, lactam, malonic acid ester, mercaptan or the like. Things. As the isocyanate compound having a blocked isocyanate group, for example, a commercially available product may be used. Examples of the commercially available product include a product name “Bernock D-550” manufactured by Dainippon Ink & Chemicals, Inc., a product name “Takenate B-815-N” manufactured by Takeda Pharmaceutical Co., Ltd., and Hoechst Examples include trade name “Aditol VXL-80” and trade name “Coronate 2507” manufactured by Nippon Polyurethane Industry Co., Ltd.

  Examples of the amino resin include those obtained by condensation or cocondensation of melamine, benzoguanamine, urea, dicyandiamide and the like with formaldehyde.

  The said hardening | curing agent may be used individually by 1 type, and may use 2 or more types together.

  The blending ratio of the curing agent is not particularly limited, and for example, per functional group introduced in at least one of the modified starch production step and the starch derivative-containing aqueous emulsion production step or one residual hydroxyl group in the starch, The average number of functional groups in the curing agent is in the range of 0.001 to 2, preferably in the range of 0.01 to 1.5.

(4) Composition for water-based paint Next, the composition for water-based paint provided by the present invention will be described with examples. Examples of the aqueous coating composition include a solution obtained by dissolving the modified starch in an aqueous solvent, the starch derivative-containing aqueous emulsion itself, a solution obtained by adding a curing agent to the solution or the starch derivative-containing aqueous emulsion, and the like. .

  The water-based paint composition may further contain a conventionally known colorant, if necessary. Examples of the colorant include organic pigments, natural pigments, inorganic pigments, and the like.

  Examples of the organic pigment include Red No. 202 (Resol Rubin BCA), Red No. 203 (Lake Red C), Red No. 204 (Rake Red CBA), Red No. 205 (Resol Red), and Red No. 206 (Resol Red CA). Red 207 (Risor Red BA), Red 208 (Risor Red SR), Red 219 (Brilliant Lake Red R), Red 220 (Deep Maroon), Red 221 (Toluidine Red), Red 228 (Perm) Ton Red), Dai No. 203 (Permanent Orange), Dai No. 204 (Pentidine Orange G), Yellow No. 205 (Pentidine Yellow G), Red No. 404 (Brilliant Fast Scarlet), Red No. 405 (Permanent Red F5R) ), No. 401 (Hansa) Range), Yellow No. 401 (Hansa yellow), Blue No. 404 (phthalocyanine blue), and the like.

  Examples of the natural dye include carcinoid dyes, flavonoid dyes, flavin dyes, quinone dyes, porphyrin dyes, diketone dyes, and betacyanidine dyes. Examples of the carotenoid pigment include carotene, carotenal, capsanthin, lycopene, bixin, crocin, canthaxanthin, anato and the like. Examples of the flavonoid pigments include anthocyanidins such as shisonin, raphanin, and enocyanin; chalcones such as safrole yellow and safflower; flavonols such as rutin and quercetin; and flavones such as cacao pigments. Examples of the flavin dye include riboflavin. Examples of the quinone colorant include anthraquinones such as lacaic acid, carminic acid (cochineal), kermesic acid, and alizarin; and naphthoquinones such as shikonin, alkanine, and echinochrome. Examples of the porphyrin pigment include chlorophyll and blood pigment. Examples of the diketone dye include curcumin (turmeric). Examples of the betacyanidine dye include betanin.

  Examples of the inorganic pigment include silicic anhydride, magnesium silicate, talc, kaolin, bentonite, mica, titanium mica, bismuth oxychloride, zirconium oxide, magnesium oxide, zinc oxide, titanium oxide, light calcium carbonate, and heavy carbonate. Calcium, light magnesium carbonate, heavy magnesium carbonate, yellow iron oxide, bengara, black iron oxide, gunjou, chromium oxide, chromium hydroxide, carbon black, calamine and the like can be mentioned.

  The colorant may be used alone or in combination of two or more.

  The blending ratio of the colorant is not particularly limited, and is, for example, in the range of 0.001 to 400 parts by weight with respect to 100 parts by weight of the solution or the starch derivative-containing aqueous emulsion, preferably 0.01 to The range is 200 parts by weight.

  The water-based paint composition may further contain a conventionally known additive as required. Examples of the additive include extender pigments, metallic pigments, colored pearl pigments, fluidity modifiers, repellency inhibitors, anti-sagging agents, UV absorbers, antioxidants, UV stabilizers, matting agents, and polishes. Agents, preservatives, curing accelerators, curing catalysts, scratch inhibitors, antifoaming agents, blocking agents and the like.

  The aqueous coating composition can be produced, for example, by dissolving or dispersing the curing agent and other additive components such as the colorant in the solution or the starch derivative-containing aqueous emulsion as necessary. The aqueous paint composition can be applied by, for example, roller coating, brush coating, dip coating, spray coating (for example, non-electrostatic coating, electrostatic coating, etc.), curtain flow coating, or the like.

  The water-based coating composition can be thermally cured using, for example, a hot air dryer, an infrared dryer, a far infrared dryer, or the like. Although the thickness in particular of a coating film is not restrict | limited, For example, it is the range of 1-200 micrometers, Preferably, it is the range of 2-150 micrometers.

  The article to be coated with the water-based paint composition is not particularly limited, and examples thereof include plastic, metal, glass, earthenware, wood, plant, rock, and sand.

  Next, examples of the present invention will be described together with comparative examples. The present invention is not limited or restricted by the following examples and comparative examples. In addition, measurement and evaluation of various properties and physical properties in each example and comparative example were performed by the following methods.

(Radical polymerizable functional group substitution degree of modified starch)
The modified starch was suspended in a 90% ethanol solution and treated with hydrochloric acid to convert the carboxyl group of the radical polymerizable functional group (maleic ester) into an acid form. Thereafter, the solution was suction filtered through a glass funnel and washed several times with a 90% ethanol solution to completely remove the remaining hydrochloric acid. Thereafter, a predetermined amount of the modified starch treated with hydrochloric acid was used, dissolved completely in water while heating to 90 ° C., and then neutralized with sodium hydroxide (NaOH) to determine the carboxyl group content. Was used to calculate the degree of radical polymerizable functional group substitution.

(Non-volatile content of water-based emulsion)
The nonvolatile content was calculated from the weight measured when the weight change at 200 ° C. became 0.1% / min using a heating type moisture meter and the weight of the aqueous emulsion before the start of measurement.

(Viscosity of aqueous emulsion)
The viscosity of the aqueous emulsion was measured using an EM viscometer under the conditions of 25 ° C. and 50 rpm.

(Preparation of coating film)
First, precipitates and the like were removed from the aqueous coating composition using a sieve. Subsequently, about 2 mL of the aqueous coating composition was dropped on a glass plate (12 cm × 17 cm) and stretched using a film applicator (TPG-1206, manufactured by TP Giken Co., Ltd.). Next, after drying at room temperature until no liquid dripping, it was put into a dryer at 60 ° C. for 60 minutes. Then, humidity was adjusted by allowing to stand for 24 hours at room temperature and normal humidity. However, for the evaluation of the drying property of the following coating film, a coating film which was taken out from the dryer and then cooled to room temperature but not subjected to the humidity control was used.

(Dryness of coating film)
After taking out from the dryer, the dryness to touch of the coating film surface cooled to room temperature was evaluated according to the following evaluation criteria.

Dryness of coating film Evaluation criteria A : The coating film was hard and did not leave a mark even when pressed with a nail.
○: The coating film is elastic, but no marks were made even when it was pressed with a nail.
(Triangle | delta): The coating film has elasticity, and when it pushed with the nail | claw, the mark was attached.
X: The coating film had a sticky feeling, and when it was touched with a finger, a fingerprint was attached.

(Finish finish)
The finish of the coating film was visually evaluated according to the following evaluation criteria.

Finishing property of coating film Evaluation standard A : Good finishing.
○: The coating film had a slight finish but a good finish.
(Triangle | delta): The wave | undulation, glossiness, and Chile skin were seen by the coating film.
X: Waviness, glossiness, and chile skin were remarkably observed in the coating film.

(Pencil hardness of coating film)
In accordance with JIS K 5600-5-4 (1999), apply a pencil lead at an angle of about 45 degrees to the surface of the coating, and move it forward about 10 mm at a uniform speed while pressing firmly to the extent that the lead does not break. It was. This was repeated 5 times while changing the test location, and the hardness notation of the hardest pencil when the coating was not torn was defined as the pencil hardness of the coating.

(Abrasion resistance of coating film)
The scratches after 20 commercially available business cards were pressed against the coating and rubbed 20 times were evaluated according to the following evaluation criteria.

Friction resistance of coating film Evaluation standard A : The coating film was not scratched at all.
○: The coating film was very slightly scratched.
Δ: Some scratches were observed on the coating film.
X: Scratches were remarkably recognized in the coating film.

(Coating adhesion)
According to JIS K 5600-5-6 (1999), 100 grids of 1 mm × 1 mm were made on the coating film. The number of grids remaining after the adhesive tape was stuck on the surface of the coating film and peeled off rapidly (remaining number / 100) was evaluated according to the following evaluation criteria.

Evaluation criteria for coating film adhesion ◎: 100/100
○: 99/100
Δ: 90/100 to 98/100
X: 0/100 to 89/100

(Alkali resistance of coating film)
After 0.5 mL of 1% NaOH aqueous solution was dropped on the surface of the coating film, it was left for 24 hours in an atmosphere at a temperature of 20 ° C. and a relative humidity of 65%. After the standing, the surface of the coating film after wiping with gauze was visually evaluated according to the following evaluation criteria.

Alkali resistance of coating film Evaluation standard A : There was no abnormality on the coating film surface.
○: Slight whitening was observed on the coating film surface.
Δ: Whitening was observed on the surface of the coating film.
X: Whitening was remarkably observed on the coating film surface.

(Solvent resistance of coating film)
Filter paper was drawn on the coating film, and 78% ethanol and 2% formalin were dropped with a dropper. This was performed 5 times at 1 hour intervals, and then allowed to stand for 2 hours, and then the change in the coating film surface was visually evaluated according to the following evaluation criteria.

Solvent resistance of the coating film Evaluation criteria ○: There was no abnormality in the coating film.
Δ: Mild swelling / peeling was observed in the coating film.
X: The coating film dissolved.

[Example 1]
(1) Modified starch production step 310 g of corn starch after acid treatment and 55 g of maleic acid dissolved in a small amount of water were mixed with powder, pre-dried with a flash dryer, and then subjected to a dry reaction at 130 ° C. for 300 minutes. In this way, modified starch MES-1 having a radical polymerizable functional group substitution degree of 0.22 and a weight average molecular weight of about 218,000 was obtained.

(2) Starch derivative-containing aqueous emulsion production process An appropriate amount of degassed distilled water was prepared using an ultrasonic washer and a suction pump. Next, 160 g of the distilled water was sampled, and 4 g of the modified starch MES-1 was added thereto to obtain a 6.3 w / w% slurry. Next, the slurry was heated to 90 ° C. to be gelatinized. Next, radically polymerizable monomers (28.8 g of BMA and 7.2 g of 2EHA) and 1.2 g of sodium dodecyl sulfate were added to 4.0 g of the gelatinized product, and a pre-emulsion was formed by stirring. Further, after heating 100.0 g of the distilled water to 80 ° C., 0.4 g of sodium dodecyl sulfate and 0.8 g of potassium peroxodisulfate were added and dissolved by stirring for 5 minutes. The pre-emulsion was added dropwise over 90 minutes while stirring the solution. Thereafter, the mixture was further stirred for 150 minutes to carry out emulsion polymerization. Thus, the composition for water-system paints (a starch derivative containing water-system emulsion) of the present Example was obtained.

[Example 2]
(1) Modified starch production step 500 g of corn starch and 48.5 g of maleic acid dissolved in a small amount of water were mixed with powder, pre-dried with a flash dryer, and then subjected to a dry reaction at 130 ° C. for 300 minutes. In this way, modified starch MES-2 having a radical polymerizable functional group substitution degree of 0.12 and a weight average molecular weight of about 97,300 was obtained.

(2) Starch derivative-containing aqueous emulsion production step Except that the modified starch MES-2 was used, the starch derivative-containing aqueous emulsion production step of this example (starch) was performed in the same manner as the starch derivative-containing aqueous emulsion production step of Example 1. A derivative-containing aqueous emulsion) was obtained.

[Example 3]
(1) Modified starch production | generation process It carried out similarly to the modified starch production | generation process of Example 1, and obtained the said modified starch MES-1.

(2) Starch derivative-containing aqueous emulsion production step Starch derivative-containing aqueous emulsion production step of Example 1 except that BMA 16.0 g and 2EHA 4.0 g were added to the gelatinized material containing 20 g of the modified starch MES-1. Similarly, the aqueous coating composition (starch derivative-containing aqueous emulsion) of this example was obtained.

[Example 4]
(1) Modified starch production | generation process It carried out similarly to the modified starch production | generation process of Example 2, and obtained the said modified starch MES-2.

(2) Starch derivative-containing water-based emulsion production step Starch derivative-containing water-based emulsion production step of Example 2 except that BMA 16.0 g and 2EHA 4.0 g were added to the gelatinized material containing 20 g of the modified starch MES-2. Similarly, the aqueous coating composition (starch derivative-containing aqueous emulsion) of this example was obtained.

[Example 5]
A water-based paint composition of this example was obtained by blending the starch derivative-containing water-based emulsion obtained in Example 1 with a colorant and an additive in the proportions shown in Table 1 below.
(Table 1)
Compounding amount (parts by weight)
Aqueous emulsion containing starch derivative 50.0
Colorant (titanium dioxide) (Tai Pure (registered trademark), manufactured by DuPont) 45.0
Antifoaming agent (KS496A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.6
Thickener (Emanon 3299RV, manufactured by Kao Corporation) 0.4
Thickening aid (Smack MP-70, manufactured by Kao Corporation) 4.0

[Example 6]
A water-based coating composition of this example was obtained in the same manner as in Example 5 except that the starch derivative-containing water-based emulsion obtained in Example 2 was used.

[Example 7]
A water-based paint composition of this example was obtained in the same manner as in Example 5 except that the starch derivative-containing water-based emulsion obtained in Example 3 was used.

[Example 8]
A water-based paint composition of this example was obtained in the same manner as in Example 5 except that the starch derivative-containing water-based emulsion obtained in Example 4 was used.

[Example 9]
The composition for water-based paints of the present Example was obtained by mix | blending a hardening | curing agent, a coloring agent, and an additive with the ratio shown in following Table 2 to the starch derivative containing water-based emulsion obtained in Example 1. FIG.
(Table 2)
Compounding amount (parts by weight)
Aqueous emulsion containing starch derivative 50.0
Curing agent (isocyanate-based, Elastolon BN-69, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 20.0
Colorant (titanium dioxide) (Tai Pure (registered trademark), manufactured by DuPont) 25.0
Antifoaming agent (KS496A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.6
Thickener (Emanon 3299RV, manufactured by Kao Corporation) 0.4
Thickening aid (Smack MP-70, manufactured by Kao Corporation) 4.0

[Example 10]
An aqueous coating composition of this example was obtained in the same manner as in Example 9, except that the starch derivative-containing aqueous emulsion obtained in Example 2 was used.

[Example 11]
An aqueous coating composition of this example was obtained in the same manner as in Example 9, except that the starch derivative-containing aqueous emulsion obtained in Example 3 was used.

[Example 12]
A water-based paint composition of this example was obtained in the same manner as in Example 9 except that the starch derivative-containing water-based emulsion obtained in Example 4 was used.

[Comparative Example 1]
(1) Biomass preparation step The starch was subjected to an acid treatment to obtain an acid-treated starch having a weight average molecular weight of about 14,400.

(2) Water-based emulsion production step A water-based paint composition (water-based emulsion) of this comparative example was obtained in the same manner as the starch derivative-containing water-based emulsion production step of Example 1 except that the acid-treated starch was used. .

[Comparative Example 2]
(1) Biomass preparation step Commercially available corn flour (manufactured by Sunny Maze, corn powder obtained by pulverizing corn) was prepared.

(2) Aqueous emulsion production process Aqueous emulsion of this comparative example was used in the same manner as the starch derivative-containing aqueous emulsion production process of Example 1 except that a slurry containing 4 g of the corn flour was heated to 90 ° C. A coating composition (water-based emulsion) was obtained.

[Comparative Example 3]
(1) Biomass preparation step Commercially available arabinoxylan (manufactured by Nippon Shokuhin Kako Co., Ltd., weight average molecular weight of about 53,000) was prepared.

(2) Water-based emulsion production process The water-based paint of this comparative example was the same as the starch derivative-containing water-based emulsion production process of Example 1 except that a slurry containing 4 g of the abiquinosilane was heated to 90 ° C. Composition (water-based emulsion) was obtained.

[Comparative Example 4]
(1) Biomass preparation process Commercially available chitosan (Kimikachitosan, Kimika Co., Ltd.) was prepared.

(2) Water-based emulsion production step The water-based paint of this comparative example was the same as the starch derivative-containing water-based emulsion production step of Example 1 except that a slurry containing 4 g of the chitosan was heated to 90 ° C. Composition (water-based emulsion) was obtained.

[Comparative Example 5]
(1) Biomass preparation step In the same manner as the biomass preparation step of Comparative Example 1, the acid-treated starch was obtained.

(2) Water-based emulsion production step The same as in the water-based emulsion production step of Comparative Example 1, except that BMA 16.0 g and 2EHA 4.0 g were added to the gelatinized material containing 20 g of the acid-treated starch. A composition for water-based paint (water-based emulsion) was obtained.

[Comparative Example 6]
(1) Biomass preparation process The corn flour was prepared in the same manner as the biomass preparation process of Comparative Example 2.

(2) Water-based emulsion production step The same procedure as in the water-based emulsion production step of Comparative Example 2, except that 16.0 g of BMA and 4.0 g of 2EHA were added to the slurry containing 20 g of corn flour heated to 90 ° C. The composition for water-based paints (water-based emulsion) of this comparative example was obtained.

[Comparative Example 7]
(1) Biomass preparation process The said arabinoxylan was prepared like the biomass preparation process of the comparative example 3. FIG.

(2) Aqueous emulsion production process Except that BMA 16.0 g and 2EHA 4.0 g were added to the slurry containing 20 g of arabinoxylan heated to 90 ° C., the same as the aqueous emulsion production process of Comparative Example 3, The composition for water-based paints (water-based emulsion) of this comparative example was obtained.

[Comparative Example 8]
(1) Biomass preparation process The chitosan was prepared like the biomass preparation process of the comparative example 4.

(2) Aqueous emulsion production step The slurry containing 20 g of chitosan was heated to 90 ° C., except that BMA 16.0 g and 2EHA 4.0 g were added, in the same manner as the aqueous emulsion production step of Comparative Example 4, The composition for water-based paints (water-based emulsion) of this comparative example was obtained.

[Comparative Example 9]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 1 was used.

[Comparative Example 10]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 2 was used.

[Comparative Example 11]
A water-based paint composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 3 was used.

[Comparative Example 12]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 4 was used.

[Comparative Example 13]
A water-based paint composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 5 was used.

[Comparative Example 14]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 6 was used.

[Comparative Example 15]
A water-based paint composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 7 was used.

[Comparative Example 16]
A water-based paint composition of this comparative example was obtained in the same manner as in Example 5 except that the water-based emulsion obtained in Comparative Example 8 was used.

[Comparative Example 17]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 1 was used.

[Comparative Example 18]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 2 was used.

[Comparative Example 19]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 3 was used.

[Comparative Example 20]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 4 was used.

[Comparative Example 21]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 5 was used.

[Comparative Example 22]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 6 was used.

[Comparative Example 23]
A water-based paint composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 7 was used.

[Comparative Example 24]
A water-based coating composition of this comparative example was obtained in the same manner as in Example 9 except that the water-based emulsion obtained in Comparative Example 8 was used.

  The modified starch produced in Examples 1 to 4 and the type and weight average molecular weight of the biomass prepared in Comparative Examples 1 to 4, obtained with the starch derivative-containing aqueous emulsion obtained in Examples 1 to 4 and Comparative Examples 1 to 4 Table 3 below shows the degree of radical polymerizable functional group substitution and the evaluation results of the water-based emulsion.

The evaluation results of the coating films of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in Table 4 below. In Comparative Example 4, a coating film could not be created by the above method.
(Table 4)
Dryability Finishability Pencil hardness Friction resistance Adhesion Alkali resistance Solvent resistance Example 1 ○ ◎ F ◎ ◎ ○ ○
Example 2 ○ ◎ F ○ ◎ △ ○
Comparative Example 1 ○ ○ B ○ × × ○
Comparative Example 2 ○ × Crack HB ◎ × △ ○
Comparative Example 3 ○ △ B × peel off ○ × ○

  As shown in the said Table 4, in Example 1, 2, the evaluation result of the coating film was favorable compared with Comparative Examples 1-3.

The evaluation results of the coating films of Examples 3 and 4 and Comparative Examples 5 to 7 are shown in Table 5 below. In Comparative Example 8, a coating film could not be created by the above method.
(Table 5)
Dryability Finishability Pencil hardness Friction resistance Adhesion Alkali resistance Solvent resistance Example 3 ○ ○ F ○ ◎ ○ ○
Example 4 ○ ○ F ○ ○ △ ○
Comparative Example 5 ○ × Crack B ○ × × ○
Comparative Example 6 ○ × Crack HB ◎ × △ ○
Comparative Example 7 ○ × crack B × peel off ○ × ○

  As shown in Table 5, in Examples 3 and 4 in which the modified starch content in the nonvolatile content of the modified starch-containing aqueous emulsion was 10 w / w%, whereas Examples 3 and 4 were 50 w / w%, Compared with Comparative Examples 5 to 7 in which the biomass content in the nonvolatile content of the emulsion was 10 w / w%, compared to Comparative Examples 5 to 7 with 50 w / w%, the evaluation results of the coating films were good.

The evaluation results of the coating films of Examples 5 and 6 and Comparative Examples 9 to 11 are shown in Table 6 below. In addition, about the comparative example 12, the coating film was not able to be created with the said method.
(Table 6)
Dryability Finishability Pencil hardness Friction resistance Adhesion Alkali resistance Solvent resistance Example 5 ○ ◎ F ◎ ◎ ○ ○
Example 6 ○ ◎ F ○ ◎ △ ○
Comparative Example 9 ○ ○ B ○ × × ○
Comparative Example 10 ○ × Crack HB ◎ × △ ○
Comparative Example 11 ○ △ B × peel off ○ × ○

  As shown in Table 6 above, Examples 1 and 2 in which the starch derivative-containing aqueous emulsion itself was a coating composition were compared with Examples 1 and 2 in which Examples 5 and 6 were blended with colorants and additives. The evaluation results of the film are equivalent, and the evaluation results of the coating film are compared with those of Comparative Examples 9 to 11 in which the colorant and the additive are blended with respect to Comparative Examples 1 to 3 in which the aqueous emulsion itself is a coating composition. It was good.

The evaluation results of the coating films of Examples 7 and 8 and Comparative Examples 13 to 15 are shown in Table 7 below. In Comparative Example 16, a coating film could not be created by the above method.
(Table 7)
Dryability Finishability Pencil hardness Friction resistance Adhesion Alkali resistance Solvent resistance Example 7 ○ ○ F ○ ◎ ○ ○
Example 8 ○ ○ F ○ ○ △ ○
Comparative Example 13 ○ × Crack B ○ × × ○
Comparative Example 14 ○ × Crack HB ◎ × △ ○
Comparative Example 15 ○ × Crack B × Haggard ○ × ○

  As shown in Table 7 above, Examples 3 and 4 in which a starch derivative-containing aqueous emulsion itself was used as a coating composition were compared with Examples 3 and 4 in which Examples 7 and 8 were blended with colorants and additives. The evaluation results of the films are equivalent, and the evaluation results of the coating films are compared with Comparative Examples 13 to 15 in which the colorant and the additive are blended, as compared with Comparative Examples 5 to 7 in which the aqueous emulsion itself is a coating composition. It was good.

The evaluation results of the coating films of Examples 9 and 10 and Comparative Examples 17 to 19 are shown in Table 8 below. In Comparative Example 20, a coating film could not be created by the above method.
(Table 8)
Dryability Finishability Pencil hardness Friction resistance Adhesion Alkali resistance Solvent resistance Example 9 ○ ◎ H ◎ ◎ ◎ ○
Example 10 ○ ◎ H ◎ ◎ ○ ○
Comparative Example 17 ○ ○ B ○ × × ○
Comparative Example 18 ○ × Crack HB ◎ × △ ○
Comparative Example 19 ○ △ B × peel off ○ × ○

  As shown in Table 8, in Examples 9 and 10 in which some of the colorants of Examples 5 and 6 were changed to curing agents, the evaluation results of the coating film were improved as compared with Examples 5 and 6, and comparison was made. The evaluation result of the coating film was favorable compared with Comparative Examples 17-19 which changed a part of coloring agent of Examples 9-11 into the hardening | curing agent.

The evaluation results of the coating films of Examples 11 and 12 and Comparative Examples 21 to 23 are shown in Table 9 below. In Comparative Example 24, a coating film could not be created by the above method.
(Table 9)
Dryability Finishability Pencil hardness Friction resistance Adhesion Alkali resistance Solvent resistance Example 11 ○ ○ H ◎ ◎ ○ ○
Example 12 ○ ○ H ○ ◎ ○ ○
Comparative Example 21 ○ × Crack B ○ × × ○
Comparative Example 22 ○ × Crack B ◎ × △ ○
Comparative Example 23 ○ × crack B × peel off ○ × ○

  As shown in Table 9, in Examples 11 and 12 in which some of the colorants of Examples 7 and 8 were changed to curing agents, the evaluation results of the coating film were improved as compared with Examples 7 and 8, and comparison was made. The evaluation result of the coating film was favorable compared with the comparative examples 21-23 which changed a part of coloring agent of Examples 13-15 into the hardening | curing agent.

  As described above, according to the present invention, the modified starch excellent in water resistance, solvent resistance, and mechanical properties is contained, and the modified starch is stably dispersed. Can be obtained at low cost. The use of the water-based paint composition of the present invention is not particularly limited, and can be widely applied to the paint field.

Claims (10)

A method for producing a water-based paint composition containing modified starch,
The manufacturing method of the composition for water-system coatings characterized by including the modified starch production | generation process which produces | generates modified starch by substituting a part of hydroxyl group of starch with a radically polymerizable functional group. The method for producing a water-based paint composition according to claim 1, further comprising a starch derivative-based water-based emulsion generating step of generating a starch derivative-containing water-based emulsion by emulsion polymerization of the modified starch and the radical polymerizable monomer in a water-based solvent. . 3. The aqueous system according to claim 1, wherein in the modified starch production step, the degree of substitution with the radical polymerizable functional group is in the range of 0.01 to 1 in terms of an average value per sugar residue of the starch. A method for producing a coating composition. The method for producing a water-based paint composition according to any one of claims 1 to 3, wherein the modified starch production step is performed by a dry reaction. The method for producing a water-based paint composition according to any one of claims 1 to 4, wherein the radical polymerizable functional group is at least one of a maleic acid ester and an itaconic acid ester. The method for producing a water-based paint composition according to any one of claims 1 to 5, wherein the modified starch has a weight average molecular weight of 300,000 or less. The weight ratio of the modified starch (A) and the radical polymerizable monomer (B) in the starch derivative-containing aqueous emulsion production step is in the range of A: B = 5: 95 to 50:50. The method for producing a composition for water-based paint according to any one of 6. In the said starch derivative containing water-system emulsion production | generation process, the manufacturing method of the composition for water-system paints as described in any one of Claim 2 to 7 which uses an emulsifier. Furthermore, the manufacturing method of the composition for water based coating materials as described in any one of Claim 1 to 8 including the hardening | curing agent mixing | blending process of mix | blending a hardening | curing agent. The method for producing a water-based coating composition according to claim 9, wherein the curing agent is at least one curing agent selected from the group consisting of polycarbodiimides, isocyanate compounds, and amino resins.