JP2009143973A - Coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a starch-based coating composition which uses biodegradable starch available from natural products, excels in storage stability as one-pack coating, and enables to form a coating film excellent in drying property, finish, pencil hardness, scratch resistance, sticking property, alkali resistance, solvent resistance and weatherability, and a coated article coated with the coating composition. <P>SOLUTION: The coating composition includes a resin composition (A) obtained by reacting starch and/or modified starch (a), a hydroxy group-containing acrylic resin (b) having a hydroxyl value of 10-170 mgKOH/g obtained by copolymerizing a polymerizable monomer mixture including 40-95 mass% of an aromatic polymerizable monomer, and a polyisocyanate compound (c). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention uses a starch derived from a natural product and has biodegradability, and is excellent in storage stability as a one-pack type paint, and also has dryness, finish, pencil hardness, scratch resistance, adhesion, alkali resistance, The present invention relates to a starch-based coating composition capable of forming a coating film excellent in solvent resistance and weather resistance, and a coated article coated with the coating composition.

In recent years, from the viewpoint of reducing the impact on the global environment, such as improving waste disposal and reducing CO ₂ emissions, it has been required to actively use biodegradable raw materials derived from natural products with low environmental impact. It has been.

  As typical materials derived from such natural products, starches that are polysaccharides or modified starches such as acetylated starch have been used in the food industry and paper industry in the past. Using these starches as raw materials, they have been commercialized in a wide range of fields such as food containers, packaging materials, cushioning material sheets, agricultural films, and disposable diapers.

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

  Further, a polysaccharide urethanized product (see Patent Document 1) characterized in that at least a part of hydroxyl groups of polysaccharides such as starch or derivatives thereof is urethanated by reaction with an isocyanate compound has been proposed ( A raw material containing at least one plant component-derived segment selected from i) starch or a modified product thereof, (ii) sugar beet, (iii) polysaccharide-based agricultural waste, and (iV) a hydroxyl-containing modified product of vegetable oil. A degradable polyurethane (see Patent Document 2) has been proposed.

  On the other hand, grafting of an acrylic resin to a polysaccharide such as starch is disclosed. For example, Patent Document 3 proposes radical graft polymerization of an unsaturated monomer to a polysaccharide such as starch.

  As is clear from these prior patents, a starch-based resin itself obtained by combining, bonding, or grafting various polymers is a known technique. However, in these technologies, structural materials, injection molding materials, sheets, and the like are assumed as uses of starch-based resins, and uses as paints are not disclosed.

  For coatings using starch-based resins, a curing agent starch composition comprising a mixture of a starch-based resin and a curing agent having a functional group that reacts in a complementary manner with at least one hydroxyl group contained in the starch molecule is reactively cured. It is disclosed that it is used as a mold paint (see Patent Document 4).

  Further, it is disclosed that an aqueous dispersion containing a modified starch and a copolymer of a polymerizable unsaturated monomer as a constituent component and having an average particle diameter of 1000 nm or less, and an aqueous coating composition containing the same are used as a reaction curable coating. (See Patent Document 5).

However, these conventional starch-based paint technologies are related to reaction-curable paints, which are excellent in storage stability and dry, finish, pencil hardness, scratch resistance, adhesion, alkali resistance, and solvent resistance. In addition, no one-pack lacquer-type starch-based paint that can form a coating film excellent in weather resistance has been available.

JP-A-5-43649 JP-A-5-186556 JP 54-120698 A Japanese Patent Laid-Open No. 2004-224887 JP 2006-52338 A

  The object of the present invention is to use starch derived from natural products and biodegradable, and is excellent in storage stability as a one-component paint, and also has dryness, finish, pencil hardness, scratch resistance, adhesion, An object of the present invention is to provide a starch-based coating composition capable of forming a coating film excellent in alkalinity, solvent resistance, and weather resistance, and a coated article coated with the starch-based coating composition.

  As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that such a problem can be solved by using a resin composition having a specific composition, and have completed the present invention. .

That is, this invention consists of the following matters, for example.
1. Hydroxyl-containing acrylic having a hydroxyl value of 10 to 170 mgKOH / g, obtained by copolymerizing starch and / or modified starch (a), a polymerizable monomer mixture containing 40 to 95% by mass of an aromatic polymerizable unsaturated monomer A coating composition comprising a resin composition (A) obtained by reacting a resin (b) and a polyisocyanate compound (c).
2. The starch and / or modified starch (a) was reacted with the isocyanate group-containing acrylic resin obtained by reacting the hydroxyl group-containing acrylic resin (b) and the polyisocyanate compound (c) with the resin composition (A). 2. The coating composition as described in 1 above.
3. The coating composition according to 1 or 2 above, wherein the component (a) contains an esterified starch in an amount of 30% by mass or more in the component (a).
4. The coating composition according to any one of 1 to 3 above, wherein the coating composition is dissolved or dispersed in an organic solvent solvent.
5. The coating composition according to any one of 1 to 4 above, which further contains a biodegradable resin (B).
6. A coated article coated with the coating composition according to any one of 1 to 5 above.

The coating composition of the present invention is excellent in storage stability and can form a coating film excellent in drying property, finishing property, pencil hardness, scratch resistance, adhesion, alkali resistance, solvent resistance and weather resistance. This starch-based coating composition is a one-pack type, and is therefore excellent in workability (without worrying about pot life). Further, since no hardener derived from petroleum resources is required, the content of components derived from natural products in the final paint can be increased, the total amount of CO ₂ emission related to the product life cycle is small, and environmental pollution can be reduced.

  Furthermore, since the coating composition of the present invention utilizes starch, which is a natural material-derived polymer material, it can be stably supplied, and can be widely applied in the fields of molding agents, inks, adhesives and the like in addition to coatings. be able to.

  Although the preferable form of this invention is demonstrated in detail below, this invention is not limited only to these forms.

  The coating composition of the present invention comprises a resin composition (A) obtained by reacting starch and / or modified starch (a), a hydroxyl group-containing acrylic resin (b), and a polyisocyanate compound (c). Is.

Starch and / or modified starch (a):
Starch useful in the present invention includes corn starch, high amylose starch, wheat starch,
Examples include unmodified starch from ground stems such as rice starch, unmodified starch from underground stems such as potato starch and tapioca starch, and esterified, etherified, oxidized, acid-treated and dextrinized starch-substituted derivatives of these starches. These can be used alone or in combination.

  The modified starch useful in the present invention is obtained by bonding an aliphatic saturated hydrocarbon group, an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon group or the like to an starch or a starch degradation product via an ester bond and / or an ether bond. The modified starch is included. Here, examples of the starch degradation product include those obtained by subjecting starch to a molecular weight reduction treatment with an enzyme, an acid, or an oxidizing agent.

  The starch or starch degradation product has a number average molecular weight in the range of 1,000 to 2,000,000, particularly 3,000 to 500,000, more particularly 5,000 to 100,000. It is preferable from the viewpoint of sex.

  In this specification, the number average molecular weight is defined in the eluent using TSK GEL4000HXL + G3000HXL + G2500HXL + G2000HXL (manufactured by Tosoh Corporation) as a separation column in accordance with JIS K0124-83 at a flow rate of 1.0 ml / min at 40 ° C. This refers to a value obtained by calculation from a chromatogram obtained with an RI refractometer and a calibration curve in terms of polystyrene using tetrahydrofuran for GPC.

  Examples of the method for modifying starch include esterification modification, and preferable modifying groups include acyl groups 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 is preferably in the range of 0.5 to 2.8, and more preferably in the range of 1.0 to 2.5. If the degree of substitution is less than 0.5, the compatibility with the later-described radical polymerizable unsaturated monomer may be insufficient, and the finish of the formed coating film may be insufficient. On the other hand, if the degree of substitution exceeds 2.8, the biodegradability may decrease.

  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 0.1 to 1.8. 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 1. It is preferable to be in the range of 5 to 2.8.

  The degree of substitution is the average number of hydroxyl groups substituted with a denaturant per monosaccharide unit constituting the starch. For example, the degree of substitution 3 is 3 present in one monosaccharide unit constituting the starch. Means that all of the hydroxyl groups have been substituted by the modifying agent, and a substitution degree of 1 means that only one of the three hydroxyl groups present in one monosaccharide unit constituting the starch is substituted by the modifying agent. Means that

  Examples of modified starch include hydrophobic organisms obtained by mixing anhydrous starch having an amylose content of 50% or more with an esterification reagent in an aprotic solvent and reacting the starch and the esterification reagent. A degradable starch ester product (see JP-A-8-502552), a starch ester modified using a vinyl ester as an esterifying reagent, wherein the vinyl ester has 2 to 18 carbon atoms in the ester group And a starch ester obtained by reacting with starch using an esterification catalyst in a non-aqueous organic solvent (see JP-A-8-188601), and starch in which polyvinyl ester is grafted together with esterification (See JP-A-8-239402 and JP-A-8-301994), having a polyester graft chain on the starch molecule, Polyester graft polymerized starch in which part or all of hydroxyl groups directly connected to the graft chain ends and starch are blocked with ester groups, and the same component as the polyester graft chain, and part or all of terminal hydroxyl groups are ester groups Examples thereof include a polyester graft polymerized starch alloy (see Japanese Patent Application Laid-Open No. 9-31308) obtained by uniformly mixing a blocked independent polyester.

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

  As the starch and / or modified starch (a), it is preferable to use esterified starch mainly in terms of storage stability of the resulting resin composition (A). The amount of esterified starch used is starch and / or modified starch. In (a), it is 30% by mass or more, preferably 50% by mass or more, and particularly preferably 70% by mass or more.

Hydroxyl group-containing acrylic resin (b)
The hydroxyl group-containing acrylic resin (b) used in the present invention generally comprises a mixture of an aromatic polymerizable unsaturated monomer, a hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers in the presence of an organic solvent and a polymerization initiator. It can obtain by carrying out a radical polymerization reaction under.

  As the above monomer mixture, the aromatic polymerizable unsaturated monomer is contained in the range of 40 to 95% by mass, preferably 50 to 90% by mass, thereby being excellent in alkali resistance, coating film hardness, scratch resistance and the like. A coated film can be formed.

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

Hydroxyl group-containing polymerizable unsaturated monomers include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, and methacrylic acid. 2-hydroxypropyl, 3-hydroxypropyl methacrylate, (meth) acrylic acid ester monomer having hydroxy group such as “Placcel F” series (lactone modified (meth) acrylic acid ester) manufactured by Daicel Chemical Industries, Ltd. C ₂ -C ₈ hydroxyalkyl esters of acrylic acid or methacrylic acid.

  Among these, it is starch and / or modified | denatured to contain at least 1 sort (s) chosen from 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and 4-hydroxybutyl acrylate. It is preferable for improving the compatibility with the starch (a) and ensuring the stability of the paint.

  Other polymerizable unsaturated monomers include, for example, carboxyl group-containing polymerizable unsaturated monomers such as acrylic acid, methacrylic acid, maleic acid, crotonic acid, itaconic acid, and fumaric acid; methyl acrylate, ethyl acrylate, acrylic acid n-propyl, isopropyl acrylate, n-, i- or t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, lauryl acrylate, cyclohexyl acrylate, methacrylic acid Methyl, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-, i- or t-butyl methacrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, etc. C1-C18 alkyl ester or cycloalkyl ester of rilic acid or methacrylic acid; N-methylol acrylamide, N-butoxymethyl acrylamide, N-methoxymethyl acrylamide, N-methylol methacrylamide, N-butoxymethyl methacrylamide, etc. N-substituted acrylamide or N-substituted methacrylamide monomers;

  The polymerizable unsaturated monomer can also contain 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 acrylate, β-methyl glycidyl acrylate, 3,4 -Epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylethyl acrylate, 3,4-epoxycyclohexylpropyl acrylate, glycidyl methacrylate, β-methylglycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, 3,4-epoxycyclohexylethyl methacrylate 3,4-epoxycyclohexylpropyl methacrylate, allyl glycidyl ether, and the like.

  The hydroxyl group-containing acrylic resin (b) can be easily prepared, for example, by subjecting a mixture of the above polymerizable unsaturated monomers to a radical polymerization reaction in an organic solvent in the presence of a polymerization initiator. A mixture of an unsaturated monomer and a mixture of a polymerization initiator are uniformly dropped and reacted at a reaction temperature of 60 to 200 ° C., preferably 80 to 180 ° C. for about 30 minutes to 6 hours, preferably 1 to 5 hours. Can be obtained.

  Examples of the organic solvent include hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. Ketone type; or a mixture thereof.

  Examples of the polymerization initiator include benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, cumyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, t-butyl peroxybenzoate, Peroxides such as lauryl peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate; α, α′-azobisisobutyronitrile, α, α′-azobis-2-methylbutyro Examples include azo compounds such as nitrile, azobisdimethylvaleronitrile, and azobiscyclohexanecarbonitrile.

  The hydroxyl group-containing acrylic resin (b) obtained as described above preferably has a hydroxyl value of 10 to 170 mgKOH / g, particularly 15 to 130 mgKOH / g from the viewpoints of finish, alkali resistance, solvent resistance, and the like. The weight average molecular weight is preferably in the range of 3,000 to 100,000, particularly 5,000 to 20,000, from the viewpoints of drying property, coating film hardness, scratch resistance, and the like.

Polyisocyanate compound (c)
The polyisocyanate compound (c) is a compound having two or more isocyanate groups in one molecule. For example, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, tris (phenyl isocyanate) ) Thiophosphate, phenylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, bis (isocyanatomethyl) cyclohexane, bis (isocyanato) methylcyclohexane, dicyclohexylmethane diisocyanate, isopropylidenebis (cyclohexyl isocyanate), 3- (2 ' -Isocyanatocyclohexyl) propyl isocyanate, dianisidine diisocyanate, diphenyl ether diisocyanate and the like. Among these, isophorone diisocyanate and hexamethylene diisocyanate are preferably used from the viewpoints of hardness, adhesion, and impact resistance.

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

Resin composition (A)
The resin composition (A) used in the present invention is obtained by reacting the above-described starch and / or modified starch (a), the hydroxyl group-containing acrylic resin (b), and the polyisocyanate compound (c). . From the viewpoint of production stability, the hydroxyl group-containing acrylic resin (b) and the polyisocyanate compound (c) are made to have an excess of isocyanate groups in the polyisocyanate compound (c) with respect to the hydroxyl groups in the acrylic resin (b). It is preferable to produce the resin composition (A) by reacting it first to produce an isocyanate group-containing acrylic resin and then reacting the resin with starch and / or modified starch (a).

  It is obtained that the isocyanate group in the polyisocyanate compound (c) is in the range of 0.5 to 10.0 equivalents, particularly 0.9 to 6.0 equivalents with respect to 1 equivalent of the hydroxyl group in the acrylic resin (b). This is preferable from the viewpoints of the finish of the coating film and the storage stability of the paint.

  Moreover, as the amount of starch and / or modified starch (a) based on the total solid content of the starch and / or modified starch (a), hydroxyl group-containing acrylic resin (b) and polyisocyanate compound (c) shown above Is preferably in the range of 95 to 25% by mass, particularly 90 to 40% by mass, from the viewpoint of production stability of the resin.

  The reaction for producing the resin composition (A) is usually performed using an organic solvent (for example, a hydrocarbon solvent such as toluene, xylene, cyclohexane or n-hexane; an ester solvent such as methyl acetate, ethyl acetate or butyl acetate; acetone) , Methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, or other ketone solvents; or a mixture thereof), and a catalyst such as monobutyl tin oxide or dibutyl tin oxide is appropriately added, and the mixture is stirred at about 50 ° C. to about 50 ° C. It can be obtained by addition reaction at a temperature of 200 ° C., preferably 60 to 150 ° C., for 30 minutes to 10 hours, preferably 1 to 5 hours. The obtained resin preferably has a number average molecular weight in the range of 3,000 to 2,000,000, particularly in the range of 5,000 to 100,000, from the viewpoint of film forming property.

  In addition, the resin composition (A) manufactured as mentioned above can be suitably used as a binder for coatings dissolved or dispersed in an organic solvent solvent.

Biodegradable resin (B)
Another biodegradable resin may be mix | blended with the coating composition of this invention. Examples of biodegradable resins (B) other than starch-based resins known on the market include plant fibers (cellulose resins), polyhydroxycarboxylic acids typified by polylactic acid, polycaprolactam, and modified polyvinyl alcohol. It is done. Aliphatic polyesters represented by polycaprolactone are also biodegradable. In addition to those listed here, many biodegradable resins are known. In the present invention, any biodegradable resin that is soluble in a solvent can be used, and among these, a cellulose-derived resin is preferred.

  Conventionally, in the paint industry, cellulose acetate butyrate, which is nitrocellulose and modified cellulose, has been widely used as a binder for lacquer or an additive resin for modification. Also in the present invention, by adding a small amount of nitrocellulose and / or cellulose acetate butyrate, the drying property of the coating film when used as a one-pack type lacquer coating is improved, and the surface hardness is increased. In addition, polyhydroxycarboxylic acid, particularly polylactic acid, has an effect of increasing the surface hardness, but the coating film tends to become brittle, and a resin derived from cellulose has a better balance of coating film performance and is easy to use. The nitrocellulose that can be suitably used in the present invention includes industrial nitrified cotton BNC-HIG-2 (trade name, manufactured by Bergerac NC, France), industrial nitrified cotton RS1-4 (trade name, Korea CNC Co., Ltd.) Swancell HM1-4 (trade name, manufactured by Kyosei Yoko Co., Ltd.), Selnova BTH1-4 (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd.), etc., and cellulose acetate butyrate is CAB381-0.1. CAB381-0.5, CAB381-2, CAB531-1, CAB551-0.01, CAB551-0.2 (all trade names, manufactured by Eastman Chemical Products) and the like.

  The blending amount of these biodegradable resins (B) is preferably 50% by mass or less, more preferably 35% by mass with respect to the total amount of the resin composition (A) as the main binder and the biodegradable resin (B). % Or less. If the blending amount exceeds 50% by mass, the film forming property of the paint is insufficient, and the finish and chemical resistance may be out of the practical range.

About Coating Composition The coating composition of the present invention can be used in conventionally known liquid coating systems such as water-based coatings and organic solvent-type coatings. Among these, organic solvent-type paints include, for example, hydrocarbon organic solvents such as toluene, xylene, cyclohexane and n-hexane, ester organic solvents such as methyl acetate, ethyl acetate and butyl acetate, acetone, methyl ethyl ketone, methyl The ones that are used as diluting solvents alone or in combination of two or more ketone-based organic solvents such as isobutyl ketone and methyl amyl ketone are very easy to use as lacquers and are very easy to use. can do.

  In the coating composition of the present invention, natural pigments, organic synthetic pigments or pigments, inorganic pigments, and glittering materials can be used as coloring components as necessary.

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

  Examples of the organic synthetic dye or pigment include those defined in Ordinance No. 30 of the Ministry of Health and Welfare. For example, Red 202 (Risor Rubin BCA), Red 203 (Rake Red C), Red 204 (Rake Red CBA), Red 205 (Risor Red), Red 206 (Risor Red CA), Red 207 (Risole) Red BA), Red 208 (Risor Red SR), Red 219 (Brilliant Lake Red R), Red 220 (Deep Maroon), Red 221 (Toluidine Red), Red 228 (Parmaton Red), orange No. 203 (Permanent Orange), Orange No. 204 (Bench Gin Orange G), Yellow 205 (Bench Gin Yellow G), Red No. 404 (Brilliant Fast Scarlet), Red No. 405 (Permanent Red F5R), Orange No. 401 ( Hansa Orange), Yellow No. 401 ( Nzaero), and the like Blue No. 404 (phthalocyanine blue).

  Inorganic pigments include silicic anhydride, magnesium silicate, talc, kaolin, bentonite, zirconium oxide, magnesium oxide, zinc oxide, titanium oxide, light calcium carbonate, heavy calcium carbonate, light magnesium carbonate, heavy magnesium carbonate, sulfuric acid Examples include barium, yellow iron oxide, red iron oxide, black iron oxide, gunjou, chromium oxide, chromium hydroxide, carbon black, and calamine.

  A glitter material is a flake pigment that imparts a glittering sensation or light interference to a coating film. Examples include flake shaped aluminum, vapor-deposited aluminum, aluminum oxide, oxybismuth chloride, mica, and titanium oxide coating. Examples include mica, iron oxide-coated mica, mica-like iron oxide, titanium oxide-coated silica, titanium oxide-coated alumina, iron oxide-coated silica, iron oxide-coated alumina, glass flakes, colored glass flakes, vapor-deposited glass flakes, and hologram films. The size of these glittering materials is preferably 1 to 30 μm in the longitudinal direction and 0.001 to 1 μm in thickness.

  The blending ratio of the coloring component may be appropriately determined according to the intended use and required performance, but is usually a biodegradable resin (B) that may be blended with the resin composition (A) as desired. ) Per 100 parts by mass of the total solid content and 0.001 to 400 parts by mass, preferably 0.01 to 200 parts by mass as the total amount of the coloring components.

  Furthermore, in the coating composition of the present invention, conventionally known surface conditioners (waxes, repellency inhibitors, antifoaming agents, etc.), plasticizers, UV stabilizers, antioxidants, fluidity modifiers are used as necessary. Antisagging agents, matting agents, polishes, preservatives, and the like can be used.

  In particular, the addition of wax may be highly effective in improving finish and chemical resistance. In the present invention, wax conventionally used for paints can be suitably used. Examples of such waxes include fatty acid ester waxes that are esterified products of polyol compounds and fatty acids, silicone waxes, fluorine waxes, polyolefin waxes, animal waxes, plant waxes, among others. At least one wax selected from polyethylene wax, silicon wax and fluorine wax is preferred.

  These waxes can be used singly or in combination of two or more kinds, and the amount added thereof is the resin composition (A) as a binder and the biodegradable resin (B) which may be blended as desired. The total solid content is 100 to 10 parts by mass, preferably 0.1 to 10 parts by mass, particularly 0.5 to 3 parts by mass.

  Moreover, although the coating composition of this invention is a 1-pack lacquer type, it is also possible to contain a hardening | curing agent in the range which does not impair storage stability. When the resin composition (A) contains a hydroxyl group, it is preferable to use an amino resin or a (blocked) polyisocyanate compound as a curing agent. The amount added depends on the type of curing agent from the viewpoint of storage stability, but the total solid content of the resin composition (A) as a binder and the biodegradable resin (B) that may be blended as desired. It is 35 mass parts or less with respect to 100 mass parts, especially 30 mass parts or less.

  It is possible to use the coating composition of the present invention in combination with a crosslinking agent such as a polyisocyanate compound as a two-component curable coating, although there is a limitation in pot life and the like.

  The coated article of the present invention is obtained by coating the surface of a substrate with the paint of the present invention. The substrate on which the starch-based paint of the present invention is applied is not particularly limited, and examples thereof include metals, plastics, glass, ceramics, concrete, paper, fibers, wood, plants, rocks, sand, and the like. These base materials may be surface-treated or undercoated as necessary.

  The coating composition of the present invention is applied or printed by, for example, roller coating, brush coating, dip coating, spray coating (non-electrostatic coating, electrostatic coating, etc.), curtain flow coating, screen printing, letterpress printing, etc. Can be used.

  The coated film is dried at less than 100 ° C. for 1 to 40 minutes and then allowed to stand at room temperature (50 ° C. or less) for 10 hours or longer, or at room temperature (50 ° C. or less) for 1 to 7 days. The solvent (and / or water) inside is volatilized to form a continuous coating film. If necessary, drying can be performed at 100 to 200 ° C. for 30 seconds to 120 minutes, preferably at 100 to 120 ° C. for 2 to 30 minutes.

  The film thickness of the coating film is not particularly limited, but the average dry film thickness is generally about 1 to 200 μm, particularly 2 to 100 μm, especially 5 to 50 μm.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited at all by these examples. “Parts” and “%” are “parts by mass” and “% by mass” unless otherwise specified.

Production Example 1: Production of acrylic resin solution 67 parts of toluene was charged into a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a condenser tube, and a dropping device, and the temperature was raised to the boiling point of toluene while stirring. The mixture was added dropwise over 2 hours. After completion of the addition, the mixture was aged for 1 hour in a refluxing state of toluene to obtain an acrylic resin solution R1 having a solid content of 60%. The hydroxyl value of the acrylic resin is 108 mgKOH / g.
"blend"
Styrene 60 parts n-butyl acrylate 15 parts 2-hydroxyethyl methacrylate 25 parts 2,2′-azobis (2-methylbutyronitrile) 5 parts Production Examples 2-8: Production of acrylic resin solution Drops in Production Example 1 Production was carried out in the same manner as in Production Example 1 except that the composition of the mixture to be blended shown in Table 1 below was obtained to obtain acrylic resin solutions R2 to R8 having a solid content of 60%. Table 1 shows the hydroxyl value of the obtained acrylic resin.

Production Example 9 Production of Modified Starch 25 parts of high amylose corn starch (manufactured by Nippon Corn Starch Co., Ltd., hydroxyl value 500 mgKOH / g) is suspended in 200 parts of dimethyl sulfoxide (DMSO), heated to 90 ° C. with stirring, and 20 minutes It was held at that temperature for gelatinization. To this solution, 20 parts of sodium bicarbonate was added as a catalyst, maintained at 90 ° C., 17 parts of vinyl laurate was added, and reacted at that temperature for 1 hour. Subsequently, 37 parts of vinyl acetate was further added and reacted at 80 ° C. for 1 hour. Thereafter, the reaction solution was poured into tap water, stirred at high speed, pulverized, filtered, dehydrated and dried to prepare modified starch. The obtained modified starch was dissolved in toluene to obtain a starch solution B1 having a solid content of 30%.

Production Example 10: Production of Resin Composition A reaction vessel equipped with a thermometer, thermostat, stirrer, and condenser was charged with 123 parts of butyl acetate and 42 parts of acrylic resin solution R1 and heated to 100 ° C. while stirring. When the temperature reached 100 ° C., 5 parts of isophorone diisocyanate was added and stirred until uniform, then 0.02 part of dibutyltin dilaurate was added as a catalyst, kept at a temperature of 100 ° C. in a nitrogen atmosphere, and remained by the following measurement method. The amount of isocyanate was determined, and the reaction was continued until the residual isocyanate was 0.135 mmol / g, and then 250 parts of starch solution B1 was added and reacted at the same temperature until the residual isocyanate was 0.001 mmol / g or less. After cooling, a resin composition A1 having a solid content of 25% was obtained.

  * Method for measuring residual isocyanate: Dissolve the sample with dioxane, add dibutylamine solution in excess and add it to the isocyanate group in the sample, then back titrate the remaining amine with hydrochloric acid, and use the remaining isocyanate from the amount used. The amount of groups was determined.

Production Examples 11 to 17: Production of Resin Composition Production was carried out in the same manner as in Production Example 10 except that the type of acrylic resin solution and the amount of residual isocyanate before addition of starch solution B1 were as shown in Table 2 below. Resin compositions A2 to A8 were obtained.

Example 1: Production of coating composition Resin composition A1 400 parts (solid content 100 parts), Alpaste FX-7640NS (Toyo Aluminum Co., Ltd., aluminum paste) 46 parts (solid content 23 parts), carbon black 2 parts and 52 parts of methyl ethyl ketone were added and sufficiently mixed with a stirrer to obtain a coating composition T1 having a solid content of 25%.

Examples 2 to 4 and Comparative Examples 1 to 4: Manufacture of coating compositions In Example 1, except that the formulation is changed to the formulation shown in Table 3 below, it was produced in the same manner as Example 1, and each Example and Comparative Example A coating composition was obtained.

Comparative Example 5: Production of coating composition 217 parts of 30% starch solution B1 (solid content 65 parts), Takenate D-170HN (produced by Mitsui Chemicals Polyurethanes Co., Ltd., isocyanurate of hexamethylene diisocyanate) 35 parts (solid) 35 parts)), Alpaste FX-7640NS (Toyo Aluminum Co., Ltd., aluminum paste) 46 parts (solid content 23 parts), carbon black 2 parts, dibutyltin laurate 0.01 parts and methyl ethyl ketone 200 parts The mixture was sufficiently mixed with a stirrer to obtain a coating composition T9 having a solid content of 25%.

Preparation and Evaluation of Test Coating Plate Using each of the coating compositions of Examples and Comparative Examples obtained above, Noryl plate SE1-701 (trade name, modified polyphenylene ether, manufactured by GE Plastics, Inc.) has a dry film thickness. Spray coating was performed so that the thickness was 8 μm. Next, forced drying was performed at 60 ° C. for 30 minutes using an electric hot air dryer, and then drying was performed at room temperature (20 ° C.) for 7 days to obtain each test plate.

  Using the obtained test plate, the test was performed according to the following test method. The results are shown in Table 4. In addition, since the coating composition of Comparative Example 5 is a two-pack type coating, storage stability is not evaluated, and a paint composition is prepared by mixing Takenate D-170HN immediately before creating a test coating plate. And spray painting.

Test Method (Note 1) Storage Stability: Each coating composition was placed in a 1 liter glass container and sealed, and the state after storage at 30 ° C. for 24 hours was visually evaluated according to the following criteria.
○: Neither gelation nor phase separation of the paint is observed.
Δ: At least one of the gelation and phase separation of the paint is slightly observed.
X: At least one of gelation and phase separation of the paint is remarkable.

(Note 2) Dryability: The paint is spray-coated on Noryl plate SE1-701 (trade name, manufactured by Nippon GE Plastics, modified polyphenylene ether) so that the dry film thickness is 8 μm, and using an electric hot air dryer. Immediately after forced drying at 60 ° C. for 30 minutes, the coated plate was cooled to room temperature, and the surface dryness to touch was evaluated according to the following criteria.
A: The coating film is hard and smooth and does not leave a mark even when pressed with a nail.
○: The coating film is elastic, but it does not leave a mark even when pressed with a nail.
(Triangle | delta): A coating film has elasticity, and when it pushes with a nail, it will become a mark.
X: The coating film has a sticky feeling, and when pressed with a nail, a mark is formed, and when pressed with the belly of a finger, a fingerprint mark is formed.

(Note 3) Finishability: The appearance of the coated surface of each test plate was visually evaluated according to the following criteria.
○: No abnormalities such as swell, gloss, and dusty skin are observed.
(Triangle | delta): At least 1 sort (s) of a wave | undulation, glossiness, and Chile skin is recognized a little.
X: At least 1 type of a wave | undulation, glossiness, and Chile skin is recognized remarkably.

  (Note 4) Pencil hardness: In accordance with JIS K 5600-5-4 (1999), a pencil lead is applied at an angle of about 45 ° to the test coating plate surface, and pressed against the test coating plate surface to the extent that the core does not break. However, it moved about 10 mm forward at a uniform speed. The hardness symbol of the hardest pencil when this operation was repeated 5 times while changing the test location and the coating film was not torn was defined as pencil hardness.

(Note 5) Scratch resistance: After a commercially available business card was pressed against the coating film and rubbed 20 times, the extent of scratching was evaluated according to the following criteria.
(Double-circle): A damage | wound is not recognized at all.
○: Slight scratches are recognized, but practical range.
Δ: Some scratches are observed.
X: Scratches are remarkably recognized.

(Note 6) Adhesiveness: After making 100 1 mm × 1 mm goby eyes on the coating film according to JIS K 5600-5-6 (1990), sticking an adhesive tape on the surface and peeling it off rapidly, The number of Gobang eye coats remaining on the paint surface was evaluated according to the following criteria.
A: Remaining number / total number = 100/100.
○: Remaining number / total number = 99/100.
Δ: Remaining number / total number = 90 to 98/100.
X: Remaining number / total number = 89 or less / 100.

(Note 7) Alkali resistance: 0.5 mL of 1% aqueous sodium hydroxide solution was dropped on the coating film surface of the test plate and allowed to stand in an atmosphere at a temperature of 20 ° C. and a relative humidity of 65% for 24 hours. The appearance of wiping with gauze was visually evaluated according to the following criteria.
○: No abnormality is observed on the coating film surface.
(Triangle | delta): Discoloration (whitening) of the coating-film surface is recognized a little.
X: Discoloration (whitening) of the coating film surface is remarkable.

(Note 8) Solvent resistance: Two filter papers were placed side by side on each test coating plate, and 78% ethanol and 2% formalin were dropped onto each filter paper with a dropper to wet the filter paper. The dropping with the dropper was performed 5 times at 1 hour intervals, and then the surface of the coating film except for the filter paper after 2 hours was visually evaluated according to the following criteria.
A: No abnormality such as swelling or peeling is observed.
○: Abnormalities such as bulges and peels are very slight, but in practical use.
Δ: Some abnormality such as blistering or peeling is observed.
X: The coating film is dissolved.

(Note 9) Weather resistance: The gloss of each coating film conforms to JIS H 8602 5.12 (1992) (water spray time 12 minutes, black panel temperature 60 ° C.), carbon arc lamp type accelerated weathering tester Sunshine Measurement was made using a weatherometer, and the time during which the gloss retention relative to the gloss before the exposure test was divided by 80% was measured and evaluated according to the following criteria.
A: More than 300 hours.
○: 200 hours or more and less than 300 hours.
Δ: 100 hours or more and less than 200 hours.
X: Less than 100 hours.

Claims (6)

  Hydroxyl-containing acrylic resin having a hydroxyl value of 10 to 170 mgKOH / g obtained by copolymerizing starch and / or modified starch (a) and a polymerizable monomer mixture containing 40 to 95% by mass of an aromatic polymerizable unsaturated monomer ( A coating composition comprising b) and a resin composition (A) obtained by reacting the polyisocyanate compound (c).   The resin composition (A) is obtained by reacting starch and / or modified starch (a) with an isocyanate group-containing acrylic resin obtained by reacting a hydroxyl group-containing acrylic resin (b) and a polyisocyanate compound (c). The coating composition according to claim 1.   The coating composition according to claim 1 or 2, wherein the component (a) contains an esterified starch in an amount of 30% by mass or more in the component (a).   The coating composition according to any one of claims 1 to 3, wherein the coating composition is dissolved or dispersed in an organic solvent-based solvent.   Furthermore, the coating composition of any one of Claims 1-4 which contains biodegradable resin (B). A coated article coated with the coating composition according to any one of claims 1 to 5.