JP4674067B2 - Modified starch-containing resin aqueous dispersion and method for producing the aqueous dispersion - Google Patents

Description

  The present invention provides a modified starch-containing resin water dispersion capable of forming a coating film having biodegradability, excellent storage stability, and excellent performance such as dryness, finish, and water resistance. The present invention relates to a method for producing the aqueous dispersion and an aqueous coating composition containing the aqueous dispersion.

In recent years, the environmental pollution of the earth has become obvious, and the construction of a recycling-oriented society that takes into account the reduction of environmental burdens is progressing, and the paint industry is also demanding the development of products that are friendly to the global environment. In such a situation, it does not contain a large amount of volatile organic compounds (VOC) such as toluene and xylene, which cause deterioration of the indoor environment. Various coating agents using the materials they have have been proposed. For example, Patent Document 1 describes a peeling and moisture-proof coating composition using a specific starch ester. The composition can form a coating film having biodegradability and good peelability and moisture resistance, but it is difficult to disperse in water because the starch ester is hydrophobic. There is a problem that the finish of the formed coating film is inferior at room temperature.
JP 2001-40267 A

  An object of the present invention is to provide a modified starch-containing resin aqueous dispersion capable of forming a coating film having excellent storage stability and excellent performance such as drying property, finishing property, and water resistance, and a method for producing the dispersion. And an aqueous coating composition comprising the dispersion.

  The present inventors solve the above-mentioned problems by using dispersed resin particles having a specific average particle diameter containing a modified starch and a (co) polymer of a polymerizable unsaturated monomer as constituents as an aqueous dispersion. As a result, the present invention has been completed.

  Thus, the present invention includes (A) modified starch and (B) dispersed resin particles having an average particle size of 1000 nm or less, which contains (co) polymer of polymerizable unsaturated monomer (m-1) as a constituent component. A modified starch-containing resin water dispersion is provided.

  The modified starch-containing resin water dispersion of the present invention has good storage stability and excellent film-forming properties, and the formed coating film has good drying and finishing properties, such as water resistance and durability. There is a remarkable effect of excellent performance. Moreover, according to the present invention, an aqueous dispersion containing a modified starch that is difficult to disperse in water can be stably produced. Furthermore, the modified starch-containing resin water dispersion of the present invention uses starch that can be stably supplied as a raw material, and has excellent properties while containing modified starch having biodegradability. It can be widely applied in the field of adhesives and the like.

  Hereinafter, the present invention will be described in more detail.

   The modified starch-containing resin aqueous dispersion of the present invention has an average particle diameter of 1000 nm or less, comprising (A) modified starch and (B) a (co) polymer of polymerizable unsaturated monomer (m-1) as a constituent component. In particular, it is an aqueous dispersion comprising dispersed resin particles in the range of 50 to 500 nm. If the average particle diameter of the dispersed resin particles exceeds 1000 nm, the storage stability of the aqueous dispersion, the finish of the coating film, etc. are inferior and the practicality is lowered, which is not preferable.

  In the present specification, the average particle size is “SALD-3100” (trade name, manufactured by Shimadzu Corporation, laser diffraction particle size distribution measuring device), and the sample is diluted with deionized water, and is about 20 ° C. It is a value when measured at the temperature of.

Modified starch (A):
In the modified starch (A), an aliphatic saturated hydrocarbon group, an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon group or the like is bonded to the starch or starch degradation product via an ester bond and / or an ether bond. The modified starch is included.

  Here, as a raw material starch, for example, a blend of one or more of various natural starches such as corn starch, potato starch, wheat starch, tapioca starch, sweet potato starch, and rice starch is used. Examples of the degradation product include those obtained by subjecting the starch to a low molecular weight treatment with an enzyme, an acid or an oxidizing agent. Among these, starch or starch degradation product having a weight average molecular weight in the range of 5,000 to 2,000,000, particularly 10,000 to 1,000,000 is preferable from the viewpoint of film forming property.

  A preferred modification method for the modified starch (A) is esterification modification, and a preferred modifying group is an acyl group having 2 to 18 carbon atoms. 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 (A) is preferably within a range of 0.5 to 2.8, and particularly preferably within a range of 1.0 to 2.5. When the degree of substitution is less than 0.5, the solubility with the polymerizable unsaturated monomer (m-1) described below 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, the speed of biodegradability may be slow.

  The modified starch preferably has a glass transition point below the starch decomposition temperature (about 350 ° C.), and it is desirable to adjust the degree of modification so as to have thermoplasticity and biodegradability, Therefore, when the number of carbon atoms of the substituent used for modification is large, a low modification level, for example, when the substituent is a stearyl group having 18 carbon atoms, the degree of ester substitution is 0.5 to 1.8. On the contrary, when the number of carbon atoms of the substituent is small, a high modification level, for example, when the substituent is an acetyl group having 2 carbon atoms, the degree of ester substitution is It is preferable to be in the range of 1.5 to 2.8.

  In the present specification, the degree of substitution is the average number of hydroxyl groups substituted by a modifier per monosaccharide unit constituting the starch. For example, the degree of substitution 3 is one monosaccharide unit constituting the starch. This means that all three hydroxyl groups present in the inside are substituted by a modifier, and a substitution degree of 1 means that only one of the three hydroxyl groups present in one monosaccharide unit constituting the starch is modified. It means being replaced by an agent.

  As an example of the modified starch (A), a hydrophobic starch obtained by mixing an anhydrous starch having an amylose content of 50% or more with an esterification reagent in an aprotic solvent and reacting the starch with the esterification reagent. Biodegradable starch ester product (see JP-T-8-502552), a starch ester modified with vinyl ester as an esterification reagent, wherein the vinyl ester has 2 carbon atoms in the ester group ~ 18, starch ester obtained by reacting with starch in a non-aqueous organic solvent using an esterification catalyst (see JP-A-8-188601), and with esterification, polyvinyl ester grafting Starch (see JP-A-8-239402 and JP-A-8-301994), polyester graft chains on starch molecules Polyester graft-polymerized starch having a graft chain terminal and a starch directly-bonded hydroxyl group partially or entirely blocked by an ester group, and the same component as the polyester graft chain, and a part or all of the terminal hydroxyl group And polyester graft polymerized starch alloy (see Japanese Patent Application Laid-Open No. 9-31308) obtained by uniformly mixing an independent polyester blocked with an ester group.

  As a more preferred example, a short-long chain mixed starch ester in which the hydrogen of the reactive hydroxyl group of the same starch molecule is substituted with a short chain acyl group having 2 to 4 carbon atoms and a long chain acyl group having 6 to 18 carbon atoms ( JP 2000-159801 A), a short chain 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 Long chain mixed starch substituted derivatives (see JP 2000-159802 A) and the like. Since these modified starches are based on starch, they are biodegradable, have thermoplastic properties, and good moldability.

(Co) polymer (B):
The (co) polymer (B) constituting the dispersed resin particles in the present invention can be obtained by (co) polymerization of a polymerizable unsaturated monomer (m-1).

  Examples of the polymerizable unsaturated monomer (m-1) include compounds containing at least one, preferably one polymerizable unsaturated group in one molecule. Examples of the polymerizable unsaturated group include: , Vinyl group, (meth) acryloyl group and the like. Thus, specifically, as the polymerizable unsaturated monomer (m-1), for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n -Butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate , Tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (manufactured by Osaka Organic Chemical Co., Ltd.), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t -Butylcyclo Alkyl or cycloalkyl (meth) acrylate such as xyl (meth) acrylate and cyclododecyl (meth) acrylate; isobornyl group-containing polymerizable unsaturated monomer such as isobornyl (meth) acrylate; adamantyl (meth) acrylate and the like Adamantyl group-containing polymerizable unsaturated monomer; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3, Epoxy group-containing polymerizable unsaturated monomers such as 4-epoxycyclohexylpropyl (meth) acrylate and allyl glycidyl ether; aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene; vinyltrimeth Alkoxysilyl group-containing polymerizable unsaturated monomers such as silane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane Siloxane macromonomer such as polydimethylsiloxane macromonomer; perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroalkyl group-containing polymerizability such as fluoroolefin Unsaturated monomer; polymerizable unsaturated monomer having photopolymerizable functional group such as maleimide group; N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, etc. Carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate; unsaturated carboxylic acids such as maleic anhydride and itaconic anhydride Anhydrous; nitrogen-containing polymerizable unsaturation such as (meth) acrylonitrile, (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, and adducts of glycidyl (meth) acrylate and amines Monomer: Hydroxyalkyl (meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate; Le; (Meth) acrylate having a hydroxyl group such as a modified ε-caprolactone of hydroxyalkyl (meth) acrylate; (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end; a polyoxyethylene chain having an alkoxy group at the molecular end (Meth) acrylate having a sulfonic acid group-containing polymerizable unsaturated monomer such as 2-acrylamido-2-methylpropane sulfonic acid, allyl sulfonic acid, sodium styrene sulfonate, sulfoethyl methacrylate and its sodium salt and ammonium salt; 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4- 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxy such as 3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4- (3-acryloxy-2-hydroxypropoxy) benzophenone Addition reaction product of hydroxybenzophenone such as benzophenone and glycidyl (meth) acrylate; UV-absorbing functional group-containing polymerization property such as 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole Unsaturated monomer; 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano- 4- (Meth) acryloylamino-2,2,6,6 Tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino- 2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1- UV-stable functional group-containing polymerizable unsaturated monomers such as crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine; acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl Styrene, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl Carbonyl group-containing polymerizable unsaturated monomers such as rumethyl ketone, vinyl ethyl ketone, vinyl butyl ketone); allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate Tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate -Neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate -Glycerol di (meth) acrylate, 1,1,1-trishydroxymethyl ether Di (meth) acrylate, 1,1,1-trishydroxymethylethanetri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate , Polyallyl compounds having at least two polymerizable unsaturated groups in one molecule such as diallyl terephthalate and divinylbenzene; fatty acid-modified polymerizable unsaturated monomers, and the like. Each can be used alone or in combination of two or more.

  In the present invention, it is preferable that the polymerizable unsaturated monomer (m-1) comprises a carboxyl group-containing polymerizable unsaturated monomer as at least a part thereof.

  Examples of the carboxyl group-containing polymerizable unsaturated monomer include (meth) acrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate, and the like. These may be used alone or in combination of two or more. Can be used in combination. By using the monomer, the storage stability of the resulting aqueous dispersion can be improved.

  The proportion of the carboxyl group-containing polymerizable unsaturated monomer used is 0.1 to 5% by weight, particularly 0.3 to 4.5% by weight, based on the total amount of the polymerizable unsaturated monomer (m-1). Further, the range of 0.5 to 4% by weight is particularly preferable.

The polymerizable unsaturated monomer (m-1) preferably includes a polymerizable unsaturated monomer having an alkyl group having 4 or less carbon atoms as at least a part thereof. Examples of the polymerizable unsaturated monomer containing an alkyl group having 4 or less carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n - butyl (meth) acrylate, i- butyl (meth) acrylate, tert- butyl (meth) can be mentioned _C 1 -C ₄ alkyl (meth) acrylate acrylate, each of these is singly or as a mixture of two or Can be used in combination. Since the monomer has good compatibility with the modified starch (A), it has an effect on the stability of the dispersion before polymerization and the storage stability of the aqueous dispersion after polymerization.

  The proportion of the polymerizable unsaturated monomer containing an alkyl group having 4 or less carbon atoms is 10 to 95% by weight, particularly 15 to 85% by weight, based on the total amount of the polymerizable unsaturated monomer (m-1). %, More particularly in the range of 20 to 75% by weight.

  The polymerizable unsaturated monomer (m-1) preferably comprises a carbonyl group-containing polymerizable unsaturated monomer as at least a part thereof.

  The carbonyl group-containing polymerizable unsaturated monomer includes a compound having one carbonyl group and one polymerizable unsaturated bond in one molecule. Specifically, for example, acrolein, diacetone acrylamide, dye Acetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrol, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), etc., are used alone or in combination of two or more. Can be used in combination. Among these, diacetone (meth) acrylamide is particularly preferable.

  By using a polymerizable unsaturated monomer (m-1) containing at least a portion thereof containing a carbonyl group-containing polymerizable unsaturated monomer and blending the resulting dispersion with a hydrazine derivative described later, Auxiliary crosslinking between the carbonyl group derived from the monomer and the hydrazine derivative can be advanced, the drying property of the coating film can be further improved, and a coating film having excellent physical properties such as weather resistance and water resistance can be formed. A composition can be prepared. The proportion of the carbonyl group-containing polymerizable unsaturated monomer used is within the range of 0.5 to 35% by weight, particularly 1 to 20% by weight, based on the total amount of the polymerizable unsaturated monomer (m-1). Is preferred.

  The polymerizable unsaturated monomer (m-1) preferably comprises a fatty acid-modified polymerizable unsaturated monomer as at least a part thereof.

  The fatty acid-modified polymerizable unsaturated monomer includes a polymerizable unsaturated monomer having a polymerizable unsaturated group at the terminal 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 Acid fatty acid etc. are mentioned, and non-drying oil fatty acid includes, for example, coconut oil fatty acid, hydrogenated coconut oil fatty acid, palm oil fatty acid and the like. 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 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-methyl glycidyl (meta ) Acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether and the like.

  As the polymerizable unsaturated monomer (m-1), the stability of the dispersion in the polymerization stage can be improved by using at least a part thereof containing a fatty acid-modified polymerizable unsaturated monomer. Further, it becomes possible to impart a feeling of meat and oxidative curability to the formed coating film. The use ratio of the fatty acid-modified polymerizable unsaturated monomer is preferably 0.5 to 40% by weight, particularly 1 to 30% by weight, based on the total amount of the polymerizable unsaturated monomer (m-1). is there.

  In the present invention, the polymerizable unsaturated monomer (m-1) is derived from the total polymerizable unsaturated monomer used from the viewpoint of the film-forming property of the formed coating film and the coating film properties such as water resistance and durability. It is desirable to select the glass transition temperature of the (co) polymer to be in the range of -20 to 50 ° C, preferably -10 to 35 ° C.

  In the present invention, the glass transition temperature (absolute temperature) is a value calculated from the following equation.

1 / Tg = W ₁ / T ₁ + W ₂ / T ₂ +... W _n / T _n
W 1 in _{formula, W} 2 ··· W _n is weight% of each monomer (= (each monomer in the amount / total weight of the monomers) × 100) be _{a; T 1, T 2 ··· T} n each It is the glass transition temperature (absolute temperature) of the homopolymer of the monomer. The glass transition temperature of the homopolymer of each monomer is a value according to Polymer Hand Book (Second Edition, edited by J. Brandrup / EHImmergut), and the glass transition temperature of the homopolymer of the monomer not described in the document is Then, a homopolymer having a weight average molecular weight of about 50,000 is synthesized, and the glass transition temperature measured by differential scanning thermal analysis is used.

  Further, in the present invention, from the viewpoint of the film-forming properties of the formed coating film and the coating film properties such as water resistance and durability, the (co) heavy weight of the total polymerizable unsaturated monomer (m-1) used is used. The coalescence should generally have a weight average molecular weight of 250,000 or less, particularly in the range of 5,000 to 240,000. When the weight average molecular weight exceeds 250,000, the average particle diameter of the dispersed resin in the aqueous dispersion becomes large, and the coating film properties such as finish may be inferior.

  In the aqueous dispersion of the present invention, the composition ratio of the modified starch (A) and the polymerizable unsaturated monomer (m-1) to the (co) polymer (B) is a weight ratio of (A) / (B). In the range of 1/99 to 85/15, particularly 5/95 to 70/30, more preferably 5/95 to 60/40.

At least one additive (C) selected from the group consisting of a plasticizer, an ultraviolet absorber, an ultraviolet stabilizer and a metal dryer:
In addition to the modified starch (A) and the (co) polymer (B) of the polymerizable unsaturated monomer (m-1), the dispersed resin particles in the modified starch-containing resin aqueous dispersion of the present invention are further plasticizers. And at least one additive (C) selected from the group consisting of an ultraviolet absorber, an ultraviolet stabilizer and a metal dryer.

  As the plasticizer, those that are highly safe for the human body are desirable. Specifically, for example, citric acid derivatives such as triethyl citrate, tributyl citrate, acetyl triethyl citrate, and tributyl acetyl citrate; diethylene glycol diacetate , Ether ester derivatives such as triethylene glycol diacetate and triethylene glycol dipropionate; glycerin derivatives such as glycerin triacetate, glycerin tripropionate and glycerin tributyrate; condensates of adipic acid and 1,4-butanediol, etc. And polyhydroxycarboxylic acids such as polycaprolactone and polypropiolactone, which can be used alone or in combination of two or more. Of these, glycerin derivatives and adipic acid derivatives are particularly preferable in terms of high plasticizing effect.

  The plasticizer can improve the film-forming property of the formed coating film, and can provide a coating film with good finish and water resistance. The proportion of the plasticizer used is in the range of 0.1 to 30% by weight, particularly 0.1 to 15% by weight, based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1). The inside is preferable.

  Examples of the ultraviolet absorber include salicylic acid derivatives such as phenyl salicylate, p-octylphenyl salicylate, 4-t-butylphenyl salicylate; 2,4-dihydroxybenzophenone, 2-hydroxy- 4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2, 2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, sodium 2,2'-dihydroxy-4,4'-dimethoxy-5 -Sulfobenzophenone, 2,2 ', 4 4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, resorcinol monobenzoate, 2,4-dibenzoyl resorcinol, 4,6-dibenzoyl resorcino Benzophenone series such as -l, hydroxydodecylbenzophenone, 2,2'-dihydroxy-4 (3-methacryloxy-2-hydroxypropoxy) benzophenone; 2- (2'-hydroxy-5'-methylphenyl) benzotriazole Benzotriazole type; other (compounds such as oxalic anilide, cyanoacrylate, etc.).

  Examples of the UV stabilizer include 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole and 2- (3,5-di-t-butyl-2-hydroxyphenyl). ) -5-chlorobenzotriazole, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6, 6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy -2,2,6,6-tetramethylpiperidine polycondensate, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, bis- (2,2 ', 6,6'-tetramethyl (Lu-4-piperidinyl) sebate, 4-benzoyloxy-2,2 ', 6,6'-tetramethylpiperidine and the like.

  The ultraviolet absorbers and ultraviolet stabilizers may be used alone or in combination as appropriate and used in combination of two or more. The use ratio of the ultraviolet absorber is 0.1 to 5% by weight, particularly 0.2 to 2% by weight, based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1). Within the range is preferred. The proportion of the UV stabilizer used is 0.1 to 5% by weight, particularly 0.2 to 3% by weight, based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1). Within the range is preferred.

  In addition, the metal dryer is blended in order to promote the oxidative hardening of the formed coating film when the dispersion resin has a group having oxidative curability, for example, aluminum, calcium, cerium. , A salt of at least one metal selected from the group consisting of cobalt, iron, lithium, magnesium, manganese, zinc, and zirconium and an acid. Examples of the acid include capric acid, caprylic acid, isodecanoic acid, Linolenic acid, naphthenic acid, neodecanoic acid, octenoic acid, oleic acid, palmitic acid, resin acid, ricinoleic acid, soybean oil fatty acid, stearic acid, tall oil fatty acid and the like can be mentioned. The use ratio of the metal dryer is in the range of 0.1 to 10% by weight, particularly 0.5 to 7% by weight, based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1). The inside is preferable.

  The dispersed resin particles in the modified starch-containing resin aqueous dispersion of the present invention may contain a surfactant as a constituent component from the viewpoint of particle stability and the like. The surfactant is preferably an anionic surfactant or a nonionic surfactant. Examples of the anionic surfactant include sodium salts such as alkylsulfonic acid, alkylbenzenesulfonic acid, and alkylphosphoric acid. Nonionic surfactants include, for example, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene Oxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, so Sorbitan monostearate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, lecithin, casein and the like.

  In addition, a polyoxyalkylene group-containing anionic surfactant having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule, the anionic group and a polymerizable unsaturated group It is also possible to use a reactive anionic surfactant having in a molecule. The reactive anionic surfactant may have a polyoxyalkylene group. These can be used alone or in combination of two or more according to the desired performance. The amount of the surfactant used is from 0.1 to 20 based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1) used from the viewpoint of stability during polymerization. It can be in the range of% by weight, in particular 0.2 to 15% by weight, more particularly 0.3 to 12% by weight.

  Further, in the modified starch-containing resin aqueous dispersion of the present invention, the above-mentioned dispersed resin particles have a core / shell in which the resin particles are used as a core and one or more polymer outer shells are provided on the core as a shell. It may be in the form of a structure. By further coating the outer layer of the dispersed resin particles containing the modified starch (A) with a polymer layer, for example, the resin composition of each layer, the set Tg, the set molecular weight, the type of (co) polymerized functional group, etc. are set as appropriate. Therefore, the degree of freedom of resin design for expressing desired physical properties can be expanded.

  The material of the polymer outer shell in the core / shell structure is not particularly limited, and examples thereof include a (co) polymer (D) of a polymerizable unsaturated monomer (m-2). The polymerizable unsaturated monomer (m-2) can be used by selecting at least one of the above-described examples of the polymerizable unsaturated monomer (m-1). Moreover, the molecular weight of a polymer outer shell can be adjusted by using together the below-mentioned chain transfer agent as needed.

  In the dispersed resin particles in the form of the core / shell structure, the (co) polymer (B) of the polymerizable unsaturated monomer (m-1) constituting the core part is -30 to 30 ° C, particularly -20 to 25 ° C. The (trans) polymer (D) of the polymerizable unsaturated monomer (m-2) constituting the shell part is preferably -20 to 100 ° C, particularly -15 to 15 ° C. It is preferred to have a glass transition temperature in the range of 80 ° C.

Modified starch-containing resin water dispersion:
The modified starch-containing resin aqueous dispersion of the present invention is, for example, such that the mixture (I) containing the modified starch (A) and the polymerizable unsaturated monomer (m-1) is 1000 nm or less in an aqueous medium. And the resulting monomer emulsion is polymerized.

  According to the above method, the dispersion is stable even in the polymerization stage, and the average particle diameter of the dispersed resin particles after polymerization can be easily controlled within the above range. Moreover, according to the above method, dispersed resin particles in which the modified starch (A) is uniformly distributed at the molecular level throughout the (co) polymer of the polymerizable unsaturated monomer (m-1) can be obtained.

  In the method of the present invention, the mixture (I) can further contain the above-mentioned additive (C). Thereby, the additive (C) can be contained in the dispersed resin particles, and as a result, the additive (C) is uniformly dispersed in the coating film formed using the aqueous dispersion of the present invention. In addition, after the coating film is formed, it is not eluted by rainwater or the like, and the effect is stably exhibited over a long period of time.

  Moreover, for the purpose of adjusting the molecular weight of the modified starch-containing resin aqueous dispersion, the mixture (I) may be polymerized in the presence of a chain transfer agent. Examples of the chain transfer agent include compounds having a mercapto group. Specific examples include lauryl mercaptan, t-dodecyl mercaptan, octyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-5-tert. -Butylthiophenol, mercaptoethanol, thioglycerol, mercaptoacetic acid (thioglycolic acid), mercaptopropionate, n-octyl-3-mercaptopropionate and the like. The amount of the chain transfer agent used is preferably in the range of 0.1 to 10% by weight based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1).

  In the above production method, the aqueous medium for dispersing and emulsifying the mixture (I) is water or a water-organic solvent mixed solution obtained by dissolving an organic solvent such as a water-soluble organic solvent in water or the like. Can be mentioned. For example, a mixed system of alcohol such as methanol, ethanol, 1-propanol, 2-propanol and water can be used.

  The mixture (I) is desirably finely dispersed by a disperser having a high energy shearing ability. Examples of the disperser include a high-pressure emulsifier, an ultrasonic emulsifier, a high-pressure colloid mill, a high-pressure homogenizer, and a high-speed stirrer. In these dispersers, it is preferable to load the mixture (I) with a high shearing force of 10 to 1000 MPa, particularly 50 to 300 MPa. In addition, the mixture (I) may be preliminarily emulsified with a disper or the like before emulsification with the machine. The dispersing apparatus to be used is not limited to these, and any dispersing machine can be used as long as the average particle diameter of the emulsified particles in the monomer emulsion obtained by emulsification dispersion can be 1000 nm or less. Can be used.

  The average particle diameter of the emulsified particles in the monomer emulsion obtained by finely dispersing the mixture (I) in the aqueous medium by the above-described method is not strictly limited, but the transparency of the formed coating film, From the viewpoints of water resistance, production stability, etc., a thickness of 1000 nm or less, preferably 50 to 700 nm, more preferably 50 to 500 nm is suitable.

  Examples of the polymerization method of the monomer emulsion include a method in which the monomer emulsion after fine dispersion is charged in a reactor equipped with a stirrer, a polymerization initiator is added, and the mixture is heated while stirring.

  The polymerization initiator may be either oil-soluble or water-soluble, and examples of the oil-soluble polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide. Organic peroxides such as: azo compounds such as azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), and the like. Examples of water-soluble initiators include cumene hydroperoxide, tert- Organic peroxides such as butyl peroxide, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobis (2-methylpropiononitrile), azobis ( 2- Tilbutyronitrile), 4,4′-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], Azo compounds such as azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}; persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate, and the like. These polymerization initiators can be used alone or in combination of two or more. Further, the polymerization initiator may be used in combination with a reducing agent such as sugar, sodium formaldehyde sulfoxylate, iron complex, sodium sulfite, ascorbate, Rongalite, etc., if necessary, to form a redox polymerization system. Thereby, it becomes easy to accelerate the polymerization rate or to perform polymerization at a low temperature.

  The amount of the polymerization initiator used is preferably in the range of 0.1 to 5% by weight based on the total amount of the modified starch (A) and the polymerizable unsaturated monomer (m-1). The addition method of this polymerization initiator can be suitably selected according to the kind and quantity. For example, it may be contained in the mixture (I) and / or an aqueous medium, or may be added all at once during the polymerization.

  In the present invention, in order to improve the mechanical stability of the particles of the modified starch-containing resin aqueous dispersion, when the modified starch-containing resin aqueous dispersion has an acidic group, it is neutralized with a neutralizing agent. It is desirable to do. The neutralizing agent is not particularly limited as long as it can neutralize acidic groups. For example, sodium hydroxide, potassium hydroxide, trimethylamine, dimethylaminoethanol, 2-methyl-2-amino-1-propanol, Examples include triethylamine and aqueous ammonia. The neutralization is desirably performed so that the pH of the modified starch-containing resin aqueous dispersion after neutralization is about 5.0 to 9.5.

  Further, the modified starch-containing resin aqueous dispersion comprising dispersed resin particles in the form of a core / shell structure is, for example, a mixture (I) comprising a modified starch (A) and a polymerizable unsaturated monomer (m-1). ) In an aqueous medium so that the average particle diameter is 1000 nm or less, and in the dispersion (II) obtained by polymerizing the resulting emulsion, a polymerizable unsaturated monomer (m-2) is obtained. ) Containing the monomer component (III) and further polymerizing.

  The monomer component (III) can be added dropwise to the dispersion (II) as it is, but generally the monomer component (III) is dispersed in advance in an aqueous medium, and the resulting monomer emulsion is added to the dispersion (II). It is desirable to drop. In this case, the average particle size of the emulsified particles in the monomer emulsion is not particularly limited.

  By this method, resin particles in the form of a core / shell structure in which the outer layer of the dispersed resin particles containing the modified starch (A) is further coated with a (co) polymer layer of a polymerizable unsaturated monomer (m-2). A modified starch-containing resin aqueous dispersion can be produced.

Aqueous resin composition:
According to the present invention, there is provided an aqueous resin composition comprising the above-described modified starch-containing resin aqueous dispersion.

  When the aqueous resin composition contains a modified starch-containing resin water dispersion produced using a carbonyl group-containing polymerizable unsaturated monomer as at least a part of the polymerizable unsaturated monomer (m-1), As a crosslinking agent, a hydrazine derivative can further be included. Thereby, the crosslinking between the carbonyl group derived from the monomer and the hydrazine derivative can be promoted, the drying property of the coating film can be further improved, and the coating film having excellent physical properties such as weather resistance and water resistance. Can be prepared. Specific examples of the hydrazine derivative include oxalic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide and the like; Monoolefinic unsaturated dicarboxylic acid dihydrazide such as acid dihydrazide, fumarate dihydrazide, itaconic acid dihydrazide; phthalic acid dihydrazide, terephthalic acid dihydrazide or isophthalic acid dihydrazide; pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotrihydrazide Trihydrazide, 1,2,4-benzenetrihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydride A polyhydrazide obtained by reacting a low polymer having a carboxylic acid lower alkyl ester group with hydrazine or a hydrazine hydrate (hydrazine hydride); a hydrazide group-containing compound such as dihydrazide carbonate; a bissemicarbazide; A polyfunctional semicarbazide obtained by excessively reacting a diisocyanate such as isophorone diisocyanate or a polyisocyanate compound derived therefrom with an N, N-substituted hydrazine such as N, N-dimethylhydrazine or the hydrazide exemplified above; Excess dihydrazide exemplified above is added to an isocyanate group in a reaction product of an active hydrogen compound containing a hydrophilic group such as polyether and polyol or polyethylene glycol monoalkyl ether. Aqueous polyfunctional semicarbazide obtained by response; compound having a semicarbazide group, such as a mixture of polyfunctional semicarbazide and aqueous polyfunctional semicarbazide; compound having a hydrazone group such as bis-acetyl-di hydrazone and the like.

  Moreover, the said aqueous resin composition can also contain the compound which has a functional group which can react with the functional group which exists in modified starch (A) and / or (co) polymer (B). By including a compound having a functional group capable of reacting with the functional group present in the modified starch (A) and / or (co) polymer (B), the water resistance and durability of the formed coating film are further improved. Can be made. The compound preferably contains two or more functional groups in one molecule. Examples of such functional group combinations include epoxy group-amino group, epoxy group-acid group, hydroxyl group-isocyanate group, carboxyl group-metal ion, carboxyl group-carbodiimide group, carboxyl group-oxazoline group, and the like. .

  The aqueous resin composition also includes water-soluble or emulsion-type acrylic resins, alkyd resins, silicone resins, fluorine resins, epoxy resins, urethane resins, polyester resins, amino resins, and the like; polyethylene glycol, polyvinyl alcohol, and the like. Water-soluble polymers; natural resins such as shellac and rosin; modified resins and pigments such as “sun eclipse cell ace” (trade name, manufactured by Nippon Shokuhin Kako, polysaccharides containing xylose and arabinose obtained from corn seed coat) Dispersant, surfactant, surface conditioner, plasticizer, anti-settling agent, antistatic agent, antibacterial agent, perfume, UV absorber, UV stabilizer, curing catalyst, dispersant, antifoaming agent, thickener, construction Membrane aids, antiseptics, fungicides, antifreezing agents, pH adjusters, flash last inhibitors, aldehyde scavengers, layered viscosity minerals, powders Or particulate activated carbon, titanium oxide photocatalyst, an additive such as low pollution agents such as alkylene glycol-modified alkyl silicate can be incorporated in combination with Tekisen selected. Furthermore, the additive (C) as described above may be included in the aqueous resin composition.

  Thus, the water-based resin composition is used for coatings such as for building, automobile outer plate, automobile parts, automobile repair, PCM, coating materials such as printing ink, additives for coating materials, and bonding agents such as nonwoven fabrics. , Adhesives, fillers, molding materials, resists and the like.

Water-based paint composition:
According to the present invention, there is further provided an aqueous coating composition comprising the above aqueous resin composition.

  The water-based paint composition may be any type of clear paint or enamel paint. When applied as an enamel paint, the aqueous paint composition can contain various color pigments, glitter pigments, extender pigments, rust preventive pigments, and the like as pigment components.

  The water-based paint composition can be applied to the surface of various base materials and old paint films. Examples of the base material include concrete, mortar, slate board, PC board, ALC board, cement calcium silicate board, Inorganic base materials such as concrete blocks, wood, stones, etc .; organic base materials such as plastics; metals such as iron and aluminum, etc. Also, as the old paint film, acrylic resin systems provided on these base materials, Examples include old paint films such as acrylic urethane resin, polyurethane resin, fluororesin, silicon acrylic resin, vinyl acetate resin, epoxy resin, and alkyd resin. A water-based or solvent-type undercoat material may be applied to these coated surfaces. If necessary, after applying the undercoat material, the aqueous coating composition can be applied as a topcoat material. On the other hand, after applying the aqueous coating composition of the present invention as an undercoat, it is also possible to apply a known aqueous overcoat.

Examples of the application method of the aqueous coating composition of the present invention include air spray coating, airless spray coating, electrostatic coating, brush coating, roller coating, lysing gun, universal gun, dipping, roll coater, curtain flow coater, and roller curtain coater. A die coater and the like, and can be appropriately selected according to the use of the substrate. As an application quantity, it can be in the range of 50-500 g / m < ² > per time, for example, Preferably it is 80-300 g / m < ² >. Moreover, you may apply repeatedly several times in the range which does not impair the coating-film external appearance. As a method for drying the formed coating film, any one of heat drying, forced drying, and room temperature drying can be employed depending on the type of the modified starch-containing resin water dispersion in the aqueous coating composition. Note that in this specification, drying conditions of less than 40 ° C. are room temperature drying, drying conditions of 40 ° C. or more and less than 80 ° C. are forced drying, and drying conditions of 80 ° C. or more are heat drying.

Hereinafter, the present invention will be described in more detail with reference to examples. “Parts” and “%” indicate “parts by weight” and “% by weight”, respectively.
Production of modified starch-containing resin water dispersion Example 1
The following components are put in a glass beaker and stirred at 2000 rpm for 15 minutes with a disper to produce a preliminary emulsion, and then the preliminary emulsion is pressurized at 150 MPa with a high-pressure emulsifier that collides the fluids by applying high-pressure energy. By processing, a monomer emulsion having an average particle size of dispersed particles of 250 nm was obtained.

Monomer emulsion composition Esterified starch (A) (Note 1) 30 parts methyl methacrylate 36 parts n-butyl acrylate 20.5 parts 2-ethylhexyl acrylate 12 parts methacrylic acid 1.5 parts "Newcol 707SF" (Note 2) ) 15 parts deionized water 85 parts

   The monomer emulsion is then transferred to a glass reaction vessel equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermometer, and reagent inlet so that the solids concentration is 45% with deionized water. Diluted. Thereafter, the temperature was raised to 85 ° C., an aqueous polymerization initiator solution in which 1 part of ammonium persulfate was dissolved in 9.4 parts of deionized water was added to the reaction vessel, and stirred for 3 hours while maintaining the temperature under a nitrogen stream. Thereafter, a polymerization initiator aqueous solution in which 0.3 part of ammonium persulfate was dissolved in 3 parts of deionized water was added, stirred for 1 hour while maintaining the temperature, cooled to 40 ° C., and adjusted to pH with dimethylaminoethanol. A modified starch-containing resin water dispersion (A-1) having a solid content concentration of 43% and an average particle size of 230 nm was obtained by adjusting to 8.0.

(Note 1) Esterified starch (A): An acetyl group and a lauryl group were ester-bonded in an organic solvent to a starch degradation product having a weight average molecular weight of 150,000, which was obtained by reducing the molecular weight of corn starch with an acid. The degree of substitution is 2.41,
The modification mole ratio was acetyl / lauryl = 1.93 / 0.48.
(Note 2) “Newcol 707SF”: trade name, manufactured by Nippon Emulsifier Co., Ltd., an anionic emulsifier having a polyoxyethylene chain, 30% active ingredient.

Examples 2-12
Modified starch-containing resin water dispersions (A-2) to (A-12) were obtained in the same manner as in Example 1 except that the monomer composition was changed as shown in Table 1.

(Note 3) Esterified starch (B): Corn starch was subjected to low molecular weight treatment with acid,
A starch decomposition product having a weight average molecular weight of 800,000 is obtained by ester-bonding an acetyl group and a lauryl group in an organic solvent, the degree of substitution is 1.94, and the molar ratio of modification is acetyl / lauryl = 1.34. The ratio was /0.60.

(Note 4) Fatty acid-modified polymerizable unsaturated monomer: In a glass reaction vessel equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermometer and reagent inlet, 280 parts of safflower oil fatty acid and 142 parts of glycidyl methacrylate The reaction was carried out at 140 ° C. with stirring to obtain a fatty acid-modified polymerizable unsaturated monomer. The reaction of epoxy groups and carboxyl groups was quantified by measuring the amount of residual carboxyl groups. It took about 5 hours to complete the reaction.
(Note 5) “Riquemar PL-012”: trade name, manufactured by Riken Vitamin Co., Ltd., glycerin diacetomonolaurate, plasticizer.
(Note 6) “TINUVINE123”: trade name, manufactured by Ciba Specialty Chemicals, piperazine UV stabilizer.
(Note 7) “TINUVINE384-2”: trade name, Ciba Specialty Chemicals, benzotriazole UV absorber.
(Note 8) “Aqualon HS-10”: trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., an anionic reactive surfactant.

Example 13
The following components are put into a glass beaker, stirred at 2000 rpm for 15 minutes with a disper to produce a preliminary emulsion, and then the preliminary emulsion is pressurized at 150 MPa with a high-pressure emulsifier that causes high-pressure energy to collide with each other. By processing, a core monomer emulsion having an average particle size of dispersed particles of 250 nm was obtained.

Monomer emulsion composition for core Esterified starch (A) (Note 1) 20 parts methyl methacrylate 28.5 parts n-butyl acrylate 12 parts 2-ethylhexyl acrylate 8 parts methacrylic acid 1.5 parts "Newcol 707SF" ( Note 2) 12 parts deionized water 65 parts

The core monomer emulsion is then transferred to a glass reaction vessel equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermometer, and reagent inlet, and the solid content concentration becomes 45% with deionized water. Diluted. Thereafter, the temperature was raised to 85 ° C., an aqueous polymerization initiator solution in which 0.8 part of ammonium persulfate was dissolved in 6.6 parts of deionized water was added to the reaction vessel, and the mixture was stirred for 3 hours while maintaining the temperature under a nitrogen stream. And the core part was manufactured.

  Next, the following components were put into another glass beaker and stirred with a disper at 2000 rpm for 15 minutes to produce a shell monomer emulsion. Then, while maintaining the temperature, the shell monomer emulsion and ammonium persulfate 0.4 A polymerization initiator aqueous solution in which a part was dissolved in 2.8 parts of deionized water was continuously added dropwise over 1 hour.

Monomer emulsion composition for shell Styrene 10 parts Methyl methacrylate 1.5 parts n-Butyl acrylate 17 parts Methacrylic acid 1.5 parts “Newcol 707SF” (Note 2) 7 parts Deionized water 26 parts

After completion of dropping, the mixture was stirred at the temperature for 1 hour, cooled to 40 ° C., adjusted to pH 8.0 with dimethylaminoethanol, and dispersed in water containing a modified starch-containing resin having a solid content concentration of 44% and an average particle size of 275 nm. A body (A-13) was obtained.

Comparative Example 1
The following components were put into a glass beaker and stirred at 2000 rpm for 15 minutes with a disper to produce a preliminary emulsion having an average particle size of 8600 nm.

Monomer emulsion composition Esterified starch (A) (Note 1) 88 parts methyl methacrylate 4.5 parts n-butyl acrylate 3.5 parts 2-ethylhexyl acrylate 1 part methacrylic acid 3 parts "Newcol 707SF" (Note 2) ) 15 parts deionized water 85 parts

The monomer emulsion is then transferred to a glass reaction vessel equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermometer, and reagent inlet so that the solids concentration is 45% with deionized water. Diluted. Thereafter, the temperature was raised to 85 ° C., an aqueous polymerization initiator solution in which 0.2 part of ammonium persulfate was dissolved in 5 parts of deionized water was added to the reaction vessel, and the mixture was stirred for 2 hours while maintaining the temperature under a nitrogen stream. Thereafter, a polymerization initiator aqueous solution in which 0.1 part of ammonium persulfate was dissolved in 3 parts of deionized water was added, stirred for 30 minutes while maintaining the temperature, cooled to 40 ° C., and adjusted to pH with dimethylaminoethanol. Adjusted to 8.0. This aqueous dispersion had very many filtration residues. The average particle size of the resin dispersion (A-14) in the sample which was sampled and diluted after removing the filtration residue was 2300 nm.

Comparative Example 2
A glass reaction vessel equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermometer, and reagent inlet was charged with 70 parts of toluene and heated to 100 ° C. A monomer mixture having the following composition prepared in another container was dropped into the reaction container over 4 hours while maintaining the temperature and stirring. After completion of the dropwise addition, the mixture was aged for 1 hour, and a polymerization initiator solution in which 5.0 g of t-butylperoxy-2-ethylhexanoate was dissolved in 1.0 g of toluene was dropped over 1 hour, and further aged for 1 hour. Then, it cooled to 40 degreeC and obtained the acrylic resin.

Monomer mixture composition Methyl methacrylate 44 parts n-butyl acrylate 30 parts 2-ethylhexyl acrylate 21 parts methacrylic acid 5 parts toluene 15 parts t-butylperoxy-2-ethylhexanoate 1.2 parts

Next, 20 parts of the acrylic resin, 80 parts of esterified starch (A) (Note 1) and 270 parts of toluene were charged into a stainless steel container and stirred in a 20 ° C. atmosphere until uniform. Thereafter, while maintaining this temperature, 10 parts of “Newcol 707SF” and 500 g of deionized water were gradually added to carry out phase inversion emulsification. Thereafter, toluene was removed under reduced pressure to obtain an aqueous dispersion (A-15). The average particle size of the aqueous dispersion (A-15) was 1800 nm. The storage stability of the aqueous dispersion (A-15) was Δ based on the following evaluation criteria.
(* 1) Storage stability 1 kg of the aqueous dispersion shown in Table 1 was put in an inner surface coated can having a capacity of 1 L and stored in a constant temperature room at 40 ° C. for 30 days. Then, it returned to room temperature, the state in a container was observed visually, and the following reference | standard evaluated.
○: Separation is not allowed,
Δ: Soft caking and separation are observed, but uniform by stirring.
X: Hard caking and separation are recognized and do not return.

Production Example 14 of water-based paint
The following components were sequentially charged in a container, and stirring was continued with a disper for 30 minutes until uniform, to obtain a pigment paste for white paint.

Pigment paste composition water 45 parts "Sura-off 72N" (Note 9) 3 parts "BYK-190" (Note 10) 6 parts "JR-605" (Note 11) 100 parts

Next, 154 parts of the pigment paste was mixed with 250 parts of an aqueous resin dispersion (A-1), 18 parts of “TEXANOL” (Note 12), 2 parts of “SN deformer 380” (Note 13) and “Adecanol UH-438” ( Note 14) 2 parts was mixed and mixed by stirring to obtain an aqueous coating composition (B-1).

Examples 14 to 26 and Comparative Examples 3 to 4
In Example 14, the aqueous coating compositions (B-2) to (B-15) were obtained in the same manner as in Example 14 except that the blending composition was as shown in Table 2 below.

(Note 9) “Sura-off 72N”: Trade name, Takeda Pharmaceutical Co., Ltd., preservative.
(Note 10) “BYK-190”: trade name, manufactured by Big Chemie, pigment dispersant.
(Note 11) “JR-605”: trade name, manufactured by Teica, titanium white.
(Note 12) “TEXANOL”: Product name, manufactured by Eastman Chemical Co., 2, 2, 4
-Trimethyl-1,3-pentanediol monoisobutyrate, film-forming aid.
(Note 13) “SN deformer 380”: trade name, manufactured by San Nopco, defoaming agent.
(Note 14) “Adecanol UH438”: trade name, manufactured by Asahi Denka Kogyo Co., Ltd., thickener.

Evaluation test The water-based coating compositions (B-1) to (B-15) were evaluated according to the following criteria. The results are also shown in Table 2.
(* 2) Appearance of coating film Each aqueous coating composition was coated on a glass plate using a 6 mil doctor blade and dried under conditions of an air temperature of 20 ° C. and a relative humidity of 60% to obtain test coating plates. The appearance of the coating film was visually evaluated after 1 day.
A: Good and excellent in feeling of meat,
○: Good, △: Somewhat bad,
X: There are defects such as cracks and chijimi.

(* 3) Gloss 60 degree gloss of the test coated plate obtained in the same manner as in (* 2) above was measured. The larger the value, the better the gloss.
(* 4) Drying properties Each aqueous coating composition was applied to a glass plate using a 6 mil doctor blade and dried for 6 hours under conditions of an air temperature of 20 ° C. and a relative humidity of 60%. We investigated and evaluated according to the following criteria.
◎: No fingerprints at all
○: Fingerprint is attached, but after a while, it returns to the original.
Δ: Fingerprint is attached and does not return.
X: A coating film adheres to a finger.

(* 5) Water resistance slate plate (70 × 150 × 5mm) on, "EP sealer transparent" (Kansai Paint Co., Ltd., acrylic emulsion sealer) and brushing so that the amount of coating of 150g / ^{m 2,} temperature What was dried for one day under the conditions of 20 ° C. and relative humidity 60% RH was used as a test material. Next, each water-based paint composition is brush-coated on the test material so that the coating amount becomes 100 g / m ^2, and after standing for 4 hours, the same water-based coating composition is further coated so that the coating amount becomes 100 g / m ^2. Each test coating plate was obtained by repeatedly coating with a brush and drying for 7 days under conditions of an air temperature of 20 ° C. and a relative humidity of 60%. The state of the coating film after visually immersing each test coating plate in clean water (20 ° C.) for 7 days was visually evaluated.
A: Good,
○: Slight luster is recognized, but practical level,
Δ: Glossiness, whitening, blistering is observed,
X: Remarkably blistering is observed, or the coating film is softened.

(* 6) Warm / cool cycle test “Ares Holder GII” (manufactured by Kansai Paint Co., Ltd., aqueous base preparation) was applied to a slate plate (70 × 150 × 5 mm) according to the JIS A 6909 repeated test Thereafter, each aqueous paint composition was applied with a brush so that the amount applied was 100 g / m ^2, and after standing for 4 hours, the same aqueous paint composition was further applied with a brush so that the amount applied was 100 g / m ^2. Each test coated plate was obtained by drying for 7 days under conditions of an air temperature of 20 ° C. and a relative humidity of 60%. [Dip in water (20 ° C.) for 18 hours to 3 hours in a −20 ° C. incubator for 3 hours to 3 hours in a 50 ° C. incubator] to visually evaluate the coating state after 10 cycles test did.
◎: No cracking, peeling, or bulge is allowed,
○: No cracking, peeling or swelling is observed, but slight glossiness is observed,
Δ: cracks, peels, bulges are observed,
X: Remarkable cracking, peeling, and blistering are observed.

(* 7) Accelerated weather resistance The test coated plate obtained in the same manner as in the above (* 4) was irradiated for 1000 hours in accordance with the accelerated weather resistance test of 9.8.1 (Sunshine carbon arc lamp type) of JIS K 5400. Then, the state of the coating film was visually evaluated.
A: No cracking, peeling or swelling is observed, and the gloss retention is 70% or more.
○: No cracking, peeling, or blistering is observed, and the gloss retention is 60% or more.
Less than 70%,
Δ: No cracking, peeling or swelling is observed, and the gloss retention is less than 60%.
X: Crack, peel, and bulge are recognized.

Claims (13)

Modified starch (A) and polymerizable unsaturated monomer (m-1) having an ester substitution degree within the range of 0.5 to 2.8 esterified with at least one acyl group having 2 to 18 carbon atoms A mixture containing the mixture (I) is finely dispersed in an aqueous medium so that the average particle diameter is 1000 nm or less, and the resulting emulsion is polymerized to produce a modified starch-containing resin aqueous dispersion Method. Modified starch (A) and polymerizable unsaturated monomer (m-1) having an ester substitution degree within the range of 0.5 to 2.8 esterified with at least one acyl group having 2 to 18 carbon atoms In a dispersion (II) obtained by finely dispersing the mixture (I) comprising an aqueous medium so that the average particle size is 1000 nm or less and polymerizing the resulting emulsion, A method for producing a modified starch-containing resin aqueous dispersion, wherein a monomer component (III) comprising an unsaturated monomer (m-2) is added and further polymerized. The method according to claim 1 or 2 , wherein the modified starch (A) is an esterified starch. The method according to any one of claims 1 to 3 , wherein at least a part of the polymerizable unsaturated monomer (m-1) is a carbonyl group-containing polymerizable unsaturated monomer. The method according to any one of claims 1 to 3 , wherein at least a part of the polymerizable unsaturated monomer (m-1) is a fatty acid-modified polymerizable unsaturated monomer. The method according to any one of claims 1 to 5, a mixture (I) further contains a plasticizer. The method according to any one of claims 1 to 6, wherein the mixture (I) further contains an ultraviolet absorber. The method according to claim 1, wherein the mixture (I) further contains a UV stabilizer. The method according to any one of claims 1 to 8, wherein the mixture (I) further contains a metal dryer. An aqueous resin composition comprising a modified starch-containing resin aqueous dispersion produced by the method according to any one of claims 1 to 9 . An aqueous coating composition comprising the aqueous resin composition according to claim 10 . A coating film forming method comprising coating the water-based coating composition according to claim 11 . A coated article formed by the method of claim 12 .