JP2006282960A - Curable starch composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable starch composition which is obtained by curing starch and is suitable for applications including a coating material, an adhesive and a printing material. <P>SOLUTION: The curable starch composition comprises a mixture of starch and a curing agent having a functional group complementarily reacting with at least one hydroxy group contained in the molecule of starch, or a modified starch having at least one substituent selected from a hydrocarbon group, an acid group, a blocked isocyanate group, isocyanate group, an oxidatively polymerizable group, a radically polymerizable unsaturated group, and an amide group in the molecule of starch; a biodegradable resin except starch; a metal complex; and a blocking agent selected from a β-diketone, an acetoacetic acid ester, a malonic ester, a ketone having a hydroxy group at a β position, an aldehyde having a hydroxy group at a β position, and an ester having a hydroxy group at a β position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  Today, plastics are used in every field of life and industry, and their production is enormous. Most of such plastics are treated as waste after use, and depending on the disposal, the global environment has been adversely affected. At present, in order to solve such problems, recycling of plastics and utilization of biodegradable polymers are considered.

  There are similar problems in the field of paint handling plastics.

  Conventional paints include, for example, crosslinkable resin paints such as melamine curable resin paints, isocyanate curable resin paints, and oxidation curable resin paints, such as metal plates (steel plates, aluminum plates, iron plates, etc.), wood, and other than the above metals Corrosion protection, design, durability, weather resistance on base materials such as inorganic materials (concrete, ceramic, glass, etc.), plastics (polyvinyl chloride, polyethylene terephthalate, polyethylene, nylon, etc.) according to the properties of each base material In order to impart functions such as property and scratch resistance, the base material is coated.

  The coating film applied to such a base material is treated by protecting the surface of the base material, and then peeling off the old coating film and incinerating or discarding it in the soil.

  However, when incineration is performed, wasteful energy is required for incineration, and further global warming may be caused by carbon dioxide generated when the coating film is incinerated. Depending on the coating film, hydrogen chloride gas is generated when incinerated, causing acid rain.

  In addition, when disposing in the soil, it is difficult to secure a land for disposal, and the coating film remains for a long period of time, destroying the natural environment or destroying the ecosystem in the soil. There is a risk of doing.

  Conventionally, polylactic acid has been well known as a biodegradable polymer in order to eliminate such problems associated with disposal (for example, Patent Document 1).

  However, when polylactic acid is used as a resin component for paints, it cannot be used as a liquid paint because of its poor solubility in organic solvents, and a highly glossy paint film is formed even if it is forcibly dispersed in an organic solvent. Cannot be used, because the coating film hardness is low and the coating film peels off with a little force, or the coating film is scratched. .

  Moreover, starch is also well-known as a biodegradable polymer (for example, patent document 2).

  Conventionally, starch blended with plasticizer is molded (casting, extrusion molding, mold molding, foam molding, etc.) and used for sheets, films, containers, corn cups, rice crackers, inner skins, etc. Yes.

  In addition, when disposing in the soil, it is difficult to secure a land for disposal, and the coating film remains for a long period of time, destroying the natural environment or destroying the ecosystem in the soil. There is a risk of doing.

  Conventionally, polylactic acid has been well known as a biodegradable polymer in order to eliminate such problems associated with disposal (for example, Patent Document 1).

  However, when polylactic acid is used as a resin component for paints, it cannot be used as a liquid paint because of its poor solubility in organic solvents, and a highly glossy paint film is formed even if it is forcibly dispersed in an organic solvent. Cannot be used, because the coating film hardness is low and the coating film peels off with a little force, or the coating film is scratched. .

  Moreover, starch is also well-known as a biodegradable polymer (for example, patent document 2).

  Conventionally, starch blended with plasticizer is molded (casting, extrusion molding, mold molding, foam molding, etc.) and used for sheets, films, containers, corn cups, rice crackers, inner skins, etc. Yes. However, considering the use of the starch itself as a resin for paints, adhesives, printing materials, sheet materials, moldings, etc., for example, water resistance is poor, and a film or molded product becomes brittle by absorbing a small amount of water. In fact, it cannot be used due to poor film hardness, scratch resistance, adhesion to the material, corrosion resistance, and the like.

  It is also known that starch molecules can be polymerized by graft copolymerization reaction (starch and vinyl monomer), polycondensation reaction (polyesterification, polyurethane formation, etc.), crosslinking reaction (polyisocyanate, polybasic acid, etc.), etc. It is. However, such a high molecular weight starch does not dissolve in an organic solvent, so that a liquid composition cannot be obtained. Also, when used as a powder material that does not use an organic solvent, the powder has poor thermal fluidity, so that it is smooth. Thus, an article excellent in coating performance could not be obtained, and application as a resin suitable for these uses was impossible.

  Conventionally, a one-component isocyanate-curable coating composition obtained by blending a polyisocyanate curing agent with a hydroxyl group-containing resin such as an acrylic resin is known. The coating is sufficiently cured even at a temperature of 120 ° C. or lower. However, for example, when a thermoplastic resin material having a low thermal deformation temperature is used, which is cured at a temperature of 60 ° C. or lower, the time required for curing is long. For this reason, conventionally known isocyanate curing catalysts such as organic tin compounds are usually blended (see Patent Document 3).

  However, conventionally known curing catalysts have improved low-temperature curability, but conversely have a problem that pot life (potential life, hereinafter the same meaning) is shortened and coating workability is inferior. In addition, it may be possible to lengthen the pot life by using a metal complex as a curing catalyst, but this has the problem that the low-temperature curability is inferior and satisfies the conflicting properties of low-temperature curability and coating workability. There was nothing in the past.

Biodegradable Plastic Handbook, published on May 26, 1995, edited by Biodegradable Plastics Research Group, P279-P291 Biodegradable Plastic Handbook, published on May 26, 1995, edited by Biodegradable Plastics Research Group, P122-P129 JP 2003-20450 JP

  Conventionally, starch has been limited in use because it is a thermoplastic resin, but it is intended to provide a curable starch composition suitable for applications such as paints, adhesives, and printing by curing starch. .

  The curable resin composition according to the present invention comprises starch, a curing agent having a functional group that reacts complementarily with at least one hydroxyl group contained in the starch molecule, and a biodegradable resin excluding starch (hereinafter referred to as this It is characterized in that it is a mixture with a composition related to a thing.

  In the curable resin composition according to the present invention, the curable starch composition is starch, polyisocyanate curing agent, biodegradable resin excluding starch, metal complex and β-diketone, acetoacetate ester, malonate ester. And a blocking agent selected from ketones having a hydroxyl group at the β-position, aldehydes having a hydroxyl group at the β-position, and esters having a hydroxyl group at the β-position.

    The curable resin composition according to the present invention includes at least one selected from a hydrocarbon group, an acid group, a blocked isocyanate group, an isocyanate group, an oxidation polymerizable group, a radical polymerizable unsaturated group, and an amide group in the starch molecule. It is characterized by being a mixture of a modified starch having a substituent and a biodegradable resin excluding starch (hereinafter, a composition using this modified starch may be referred to as a curable resin composition II). And

  In the curable resin composition according to the present invention, the curable starch composition comprises an isocyanate group-containing modified starch, a curing agent that reacts with an isocyanate group, a biodegradable resin excluding starch, a metal complex and a β-diketone, It contains a blocking agent selected from acetates, malonic esters, ketones having a hydroxyl group at the β-position, aldehydes having a hydroxyl group at the β-position, and esters having a hydroxyl group at the β-position.

    In the curable resin composition according to the present invention, a fiber-based resin is preferable as a biodegradable resin excluding starch, and nitrocellulose is more preferable.

  The present invention will be described in detail below.

  The curable starch composition I of the present invention is a mixture of starch, a curing agent having a functional group that reacts complementarily with at least one hydroxyl group contained in the starch molecule, and a biodegradable resin excluding starch. is there.

  Examples of the starch include conventionally known starches and modified starches of the present invention described below.

  The curing agent is not particularly limited as long as it is a curing agent having a functional group that reacts in a complementary manner with a hydroxyl group (including a methylol group, hereinafter the same meaning is included) contained in the starch molecule. Conventionally known ones are included.

  Examples of the functional group that reacts complementarily include an isocyanate group, an acid anhydride group, an acid group, an amino group, an amide group, and an imino group.

  Conventionally known starches include, for example, ground stem unmodified starch such as corn starch, high amylose starch, wheat starch, and rice starch, unmodified starch of root stem such as potato starch, tapioca starch, and low-esterification of these starches. , Etherified, oxidized, acid-treated, dextrinized starch substituted derivatives, and the like. These can be used alone or in combination.

  In addition, as the above-described curing agent, for example, a curing agent that has been conventionally used as a curing agent for paints, such as the following (which may be blocked) polyisocyanate compound and amino resin, can be used.

  Specifically, the polyisocyanate compound may be a free isocyanate compound or a blocked isocyanate compound. Examples of the polyisocyanate compound having a free isocyanate group include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate, cyclic aliphatic diisocyanates such as xylene diisocyanate or isophorone diisocyanate, tolylene diisocyanate or 4,4 ′. -Organic diisocyanates such as aromatic diisocyanates such as diphenylmethane diisocyanate itself, or adducts of excess amounts of these organic diisocyanates with polyhydric alcohols, low molecular weight polyester resins, water, etc., or each organic diisocyanate listed above And polymers such as isocyanate and biuret.

In addition to the above,
The following general formula 1

(In the formula, X represents —CH ₃ or —C _m H _2m NCO. N represents an integer of 1 to 10, and m represents an integer of 1 to 8.)
In particular, the polyisocyanate compound represented by the above chemical formula is excellent in reactivity with the hydroxyl groups in the starch, can form a film excellent in various performances, and can be blocked even when a blocked polyisocyanate compound is used. There is an effect that the low temperature dissociation property of the agent is excellent.

  In addition, as the polyisocyanate compound having a blocked isocyanate group, the above-mentioned polyisocyanate compound having a free isocyanate group is blocked with a known blocking agent such as oxime, phenol, alcohol, lactam, malonic ester, mercaptan, etc. Is mentioned.

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

  The blending ratio of the curing agent is preferably in the range of 0.001 to 2, more preferably 0.01 to 1.5 average functional groups in the curing agent per hydroxyl group in the starch. When the average is less than 0.001, the film performance such as water resistance is deteriorated. On the other hand, when the average is more than 2, the biodegradability is deteriorated.

  The biodegradable resin excluding the starch used in the present invention is a conventionally known biodegradable resin excluding the starch. As this, for example, a fibrous resin, polycaprolactone, polyvinyl acetate, polylactic acid, polyether, polyacrylic acid, polyethylene, polyester, polyamide, polyolefin, polyether, polyvinyl alcohol, rosin, rosin derivative, terpene, Examples include terpene derivatives and natural rubber.

  Among these, since the fiber-based resin has a hydroxyl group in the molecule, it reacts with the above curing agent (isocyanate, melamine, etc.) using this hydroxyl group as a reactive group to form a cured film, resulting in water resistance and adhesion. Since it is possible to form a film excellent in film performance such as processability and weather resistance, it is preferable to use this film.

Examples of the fiber-based resin include nitrocellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and modified products thereof.
Furthermore, nitrocellulose, which is a nitrate ester of cellulose among the fiber-based resins, is excellent in compatibility with starch and modified starch, so it can form a film with an excellent appearance, and further, adhesion to materials such as plastic, durability, It is preferable to use this because it has excellent performance such as recoatability.

In the curable resin composition of the present invention, as components other than the above-mentioned starch and curing agent, metal complexes and β-diketones, acetoacetic esters, malonic esters, ketones having a hydroxyl group at the β-position, β-position A blocking agent selected from aldehydes having a hydroxyl group and esters having a hydroxyl group at the β-position can be blended.
The metal complex is a complex of at least one metal selected from aluminum, zirconium, titanium, and tin.

  A conventionally well-known thing can be used as a metal complex. The metal complex is preferably an organometallic chelate compound. Specifically, for example, tris (ethylacetoacetate) aluminum, tris (propylacetate) aluminum, tris (butylacetoacetate) aluminum, propoxybis (Ethylacetoacetate) aluminum, tris (acetylacetonato) aluminum, tris (propionylacetonato) aluminum, tris (acetoacetonato) aluminum, tetrakis (ethylacetoacetate) titanium, tetrakis (acetylacetonato) titanium, di Propoxybis (ethylacetoacetate) titanium, dipropoxybis (acetylacetonato) titanium, tetrakis (acetylacetonato) zirconium, tetrakis (propylacetoacetate) ) Zirconium, tetrakis (ethylacetoacetate) zirconium, monobutylbis (ethylacetoacetate) tin acetate, monobutylbis (acetylacetonato) tin octate, bis (ethylacetoacetate) tin diacetate, butylbis (acetyl) Acetonato) tin octate, bis (acetylacetonato) tin dioctate and the like. These can be used alone or in combination of two or more.

  The compounding ratio of the metal complex is 0.1 to 10 parts by weight, preferably 0.2 to 8 parts by weight, based on 100 parts by weight of the solid content of the curable resin composition with starch and polyisocyanate curing agent. When the blending ratio is less than 0.1 parts by weight, the curability is inferior, and when it exceeds 10 parts by weight, the coating becomes brittle and the workability is deteriorated.

  Examples of the blocking agent include β-diketones, acetoacetic esters, malonic esters, ketones having a hydroxyl group at the β-position, aldehydes having a hydroxyl group at the β-position, and esters having a hydroxyl group at the β-position. Specifically, for example, β-diketones: acetylacetone, acetoacetate esters: methyl acetoacetate, malonate esters: ethyl malonate, ketones having a hydroxyl group at β-position: diacetone alcohol, hydroxyl group at β-position Examples include aldehydes having: salicylaldehyde, esters having a hydroxyl group at the β-position: methyl salicylate, and the like. Among the above-mentioned, acetylacetone which exhibits a long pot life and an excellent effect of low temperature curability is preferable.

  The mixing ratio of the blocking agent is 1 to 30 parts by weight, preferably 2 to 20 parts by weight, based on 100 parts by weight of the solid content of the curable resin composition with starch and polyisocyanate curing agent. When the blending ratio is less than 1 part by weight, the pot life time is shortened, and when it exceeds 30 parts by weight, the hardness of the coating is lowered.

  In addition to the above-described components, a polyhydric alcohol can be blended in the curable resin composition with starch and a polyisocyanate curing agent.

  The polyhydric alcohol is preferably used in advance as a curing catalyst premixed solution of a curable resin composition of starch and a polyisocyanate curing agent.

  When the curing catalyst premixed solution is used, the compatibility between the metal complex and the starch or polyisocyanate curing agent is improved, so that the curing is uniform, the finished appearance and the coating performance are excellent, and the pot life is prolonged. .

  Examples of the polyhydric alcohol include polyhydric alcohols having a number average molecular weight of 100 to 10,000, preferably 200 to 5,000. Specifically, for example, ethylene glycol, methylene glycol, propylene glycol, butylene glycol, dimethylene glycol, diethylene glycol, dipropylene glycol, dibutylene glycol, trimethylene glycol, triethylene glycol, tripropylene glycol, tributylene glycol and the above Other than polymethylene glycol, polyethylene glycol (eg, number average molecular weight 1000, 2000, etc.), polypropylene glycol (eg, number average molecular weight 1000, 2000, etc.), polybutylene glycol, and the like.

    The blending ratio of the polyhydric alcohol is 10 to 200 parts by weight, preferably 20 to 200 parts by weight with respect to 100 parts by weight of the metal complex. When the blending ratio is less than 10 parts by weight, the compatibility of the metal complex with the curable resin composition is lowered or the pot life time is shortened. On the other hand, when it exceeds 200 parts by weight, the curability is lowered.

  In the curable starch composition I of the present invention, for example, conventionally known colorants can be blended as necessary. As the colorant, organic pigments, natural pigments, and inorganic pigments are used.

  The organic pigments are legal dye systems defined by the Ministry of Health and Welfare Ordinance No. 37, and mainly tar dye systems. For example, Red 202 (Risor Rubin BCA), Red 203 (Lake 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 (Pentidine Orange G), Yellow 205 (Pentidine Yellow G), Red No. 404 (Brilliant Fast Scarlet), Red No. 405 (Permanent Red F5R), Orange No. 401 ( Hansa Orange), yellow 401 Hansa Yellow), and the like Blue No. 404 (phthalocyanine blue).

  Specific examples of natural pigments include β-carotene, β-apo-8-carotinal, capsanthin, lycopene, bixin, crocin, canthaxanthin, and anato in carotenoids, and sosonin, raphanin, and enocyanin in flavonoids. Anthocyanidins, chalcones such as safrole yellow and safflower, flavonols such as rutin and quercetin, flavones such as cacao pigments, flavin, riboflavin, etc., quinones, lacaic acid, carmine Anthraquinones such as acid (cochineal), kermesic acid, alizarin, naphthoquinones such as shikonin, alkanine, echinochrome, etc., polyphyllin, chlorophyll, hemoglobin, diketone, curcumin (tar Rick) etc., in Betashianijin system, and the like betanin.

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

  The blending ratio of the colorant may be appropriately determined according to the intended use and required performance, but is usually 0.001 to 400 parts by weight, preferably 0. 0 to 100 parts by weight per 100 parts by weight of the curable starch composition. The range is 01 to 200 parts by weight.

  In addition, the curable starch composition I of the present invention may include conventionally known solvents such as ester solvents, aromatic solvents, ketone solvents, ester solvents, aliphatic hydrocarbon solvents and the like as necessary. Can be used. These solvents can be used alone or in combination of two or more.

  In addition, the curable starch composition I of the present invention may include additives conventionally added to paints, adhesives, printing, sheet materials, and molded articles as necessary, such as coloring pigments and extender pigments other than those described above. , Metallic pigments, colored pearl pigments, fluidity modifiers, anti-repellent agents, anti-sagging agents, UV absorbers, antioxidants, UV stabilizers, matting agents, polishing agents, preservatives, curing accelerators, other than the above The curing catalyst, scuffing agent, antifoaming agent and the like can be used without particular limitation.

  Next, the curable starch composition II using the modified starch of the present invention will be described.

  The modified starch used in the present invention has at least one kind selected from a hydrocarbon group, an acid group, a blocked isocyanate group, an isocyanate group, an oxidation polymerizable group, a radical polymerizable unsaturated group, and an amide group in the starch molecule. Has a substituent.

  As the starch used for the modification, the above-mentioned starch can be used.

  The modified starch substituted with hydrocarbon groups is described below.

  The hydrocarbon group as the substituent is an effect of improving the solubility of starch in an organic solvent, an effect of improving the compatibility when other resins and curing agents are blended, a coating, a molded product, a sheet, an adhesive, It is possible to improve durability such as water resistance, corrosion resistance, and weather resistance by imparting hydrophobicity to the effect of improving mechanical properties of a molded product, etc., and coating, molded product, sheet, adhesive, and molded product.

  The starch containing a hydrocarbon group is one in which a hydrocarbon group is bonded via an ester bond, and is represented by the following structural formula.

  2

In the formula, examples of R ₁ include an alkyl group, a cycloalkyl group, and an aryl group.

Furthermore, an active hydrogen-containing group-introduced body such as a hydroxyalkyl group or an aminoalkyl group may be contained within a range that does not affect the effects of the present invention.
The hydrocarbon group preferably has 2 to 24 carbon atoms.
In the formula, A represents a hydroxyl group, —OOR ₁ , —OOR ₆ , —OOR ₇ , —OOR ₈ , —OOR ₉ , or —OOR ₁₀ . _{Incidentally, -OOR 6, -OOR 7, -OOR} 8, for -OOR _9, and -OOR ₁₀ have the same meanings as those described below.

  Examples of the alkyl group include ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl and the like. These alkyl groups may be either linear or branched. Further, it may be an alkyl group substituted with an alkoxyl group such as methoxymethyl, ethoxyethyl, propoxypropyl and the like.

  Examples of the cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like. Among these, a cyclohexyl group is particularly preferable.

  Examples of the aryl group include phenyl, toluyl, xylyl, methylphenyl, dimethylphenyl, and the like.

In the above-mentioned modified starch, R ₁ may be a random or block-arranged hydrocarbon group selected from, for example, 2 to 24 carbon atoms in the entire modified starch molecule of the modified starch, or 2 carbon atoms. A short-chain hydrocarbon group selected from ˜4 and a long-chain hydrocarbon group selected from 5 to 24 carbon atoms may be arranged randomly or in a block shape.

  The modified starch having a hydrocarbon group is obtained by reacting an alkyl ketene dimer, a cyclic ester (such as lactone), an acid anhydride, an acid halide, or a vinyl compound in a non-aqueous organic solvent with hydrogen and acyl of a reactive hydroxyl group on the starch molecule. It can be easily synthesized by reacting with an oxidization (esterification) catalyst.

The alkyl ketene dimer is composed of a combination of various alkyl groups.
Chemical 3

(Wherein R _{2 is} an alkyl group having 5 to 17 carbon atoms and an aryl group).

Examples of cyclic esters (caprolactones) include ε-caprolactone (C ₆ ), γ-caprolactone (C ₈ ), γ-laurolactone (C ₁₂ ), γ-stearolactone (C ₁₈ ), formula (CH ₂₎ n COO (However, n = 5 to 17) in the macrocyclic lactone or the like shown alone or in combination with use.
The alkyl group can be selected from the alkyl groups described above. Examples of the aryl group include the same groups as described above.

Examples of acid anhydrides and acid halides include halides and anhydrides such as caprylic acid (C ₈ ), lauric acid ( ₁₂ ), palmitic acid (C ₁₆ ), stearic acid (C ₁₈ ), and oleic acid (C ₁₈ ). Can be used.

Examples of vinyl compounds include vinyl acetate (C ₂ ), vinyl propionate (C ₃ ), vinyl butanoate (C ₄ ), vinyl caproate (C ₆ ), vinyl acrylate (C ₃ ), and vinyl crotonate (C _4). ), Vinyl caprylate (C ₈ ), vinyl laurate (C ₁₂ ), vinyl palmitate (C ₁₆ ), vinyl stearate (C ₁₈ ), vinyl oleate (C ₁₈ ) and other saturated or unsaturated aliphatic carboxylic acids It is possible to use vinyl esters of aromatic carboxylic acids such as acid vinyl esters, vinyl benzoates and vinyl P-methylbenzoates, and further, branched saturated aliphatic carboxylic acid vinyl esters represented by the following structural formula.

  4

_{(Wherein, R 3, R 4, R} 5 are all the total number of carbon atoms in the alkyl group is 4 to 16.) And the like. The alkyl group can be selected from the alkyl groups described above.

  As the non-aqueous organic solvent, raw material starch can be dissolved. Specifically, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), pyridine, etc. are used singly or in combination, and further to them. A mixture of organic solvents can be used.

  In addition, as esterification (acylation) catalysts, metal hydroxides, mineral salts, carbonates, organic compounds or alkali metal alkoxides belonging to period 5 in the periodic table, organic intercalation catalysts, amino compounds One or more of these are selected and used. Specific examples include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; alkali metal organic acid salts such as sodium acetate and sodium p-toluenesulfonate; barium hydroxide and calcium hydroxide. Alkaline earth metal hydroxides such as alkaline earth metal hydroxides, calcium acetate, calcium propionate, barium p-toluenesulfonate; sodium phosphate, calcium phosphate, sodium hydrogen sulfite, sodium carbonate, sodium hydrogen carbonate, potassium carbonate , Inorganic acid salts such as potassium hydrogen carbonate, potassium sulfate, sodium aluminate and potassium zincate; amphoteric metal hydroxides such as aluminum hydroxide and zinc hydroxide; amino compounds such as dimethylaminopyridine and diethylaminoacetic acid N-trimethyl- N-propylan Niumukurorido, quaternary ammonium compounds such as N- tetraethylammonium chloride. And it does not specifically limit regarding the timing and method of using these catalysts.

  In the modified starch described above, by leaving a hydroxyl group in the starch, a curing agent that reacts with the hydroxyl group (for example, the melamine resin, the (optionally blocked) polyisocyanate, etc.) can be blended. .

  The blending ratio of the curing agent is preferably in the range of 0.001 to 2, more preferably 0.01 to 1.5 average functional groups in the curing agent per hydroxyl group in the starch. When the average is less than 0.001, the film performance such as water resistance is deteriorated. On the other hand, when the average is more than 2, the biodegradability is deteriorated.

  In the modified starch used in the present invention, the modified starch having an acid group in the starch molecule is described below.

  The acid group as the substituent includes a carboxyl group, phosphoric acid and the like, and a carboxyl group is particularly preferable. The acid group can be used as a hydrophilic group for dissolving or dispersing the modified starch in water.

  The acid group has a substitution degree of 0.01 to 2.5, particularly 0.1 to 2.0.

  When the degree of substitution is less than 0.01, the reactivity and water dispersibility are poor.

  Those containing acid groups (carboxyl groups, phosphoric acid groups, etc.) are neutralized with basic compounds (amine compounds, etc.) as necessary, dissolved or dispersed in water, and anionic water-based paints (including electrodeposition paints) Can be used as In addition, the modified starch can be cross-linked by using a curing agent such as polyepoxide with an acid group to form a cured film excellent in film durability such as processability, water resistance, corrosion resistance, and weather resistance.

  As starch containing an acid group, what is shown by the following structural formula is mentioned, for example.

  5

In the formula, R ₆ is an acid group-containing residue reacted with a hydroxyl group of starch. B is a hydroxyl group, —OOR ₁ , —OOR ₆ , —OOR ₇ , —OOR ₈ , —OOR ₉ , or —OOR ₁₀ . Incidentally, the _{-OOR 1, -OOR 6, -OOR 7} , -OOR 8, for -OOR _9, and -OOR ₁₀ have the same meanings as those hereinbefore or hereinafter.

  The acid group-containing residue is specifically a residue obtained by reacting an acid group-containing compound such as an acid anhydride, polycarboxylic acid, or phosphoric acid with a hydroxyl group.

  The polycarboxylic acid is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, succinic acid, adipic acid, sebacic acid , Trimellitic acid, pyromellitic acid and the like. Examples of acid anhydrides include these acid anhydrides. In addition to the above, polycarboxylic acid resins (acrylic resins, polyester resins, etc.) can also be used.

  In this way, a carboxyl group or the like is introduced through an ester bond by the reaction between the hydroxyl group in the starch molecule and the reactive compound.

    Examples of the polyepoxide that can be used as the curing agent described above include conventionally known epoxy resins having at least one epoxy group in one molecule, for example, a radically polymerizable monomer containing an epoxy group (for example, (3,4) -Epoxycyclohexylmethyl (meth) acrylate), glycidyl (meth) acrylate, etc.) homoradical polymers, such monomers and other radical polymerizable monomers (for example, (meth) acrylic acid alkyl or cycloalkyl having 1 to 24 carbon atoms) Ester, styrene, etc.), Epolide GT300 (Daicel Chemical Industries, Ltd., trade name, trifunctional alicyclic epoxy resin), Epolide GT400 (Daicel Chemical Industries, Ltd., trade name) Tetrafunctional alicyclic epoxy resin), EHPE (Daicel Chemical Industries, Ltd.) , Trade name, trifunctional alicyclic epoxy resin), bisphenol type epoxy resin, novolak type epoxy resin, ε-caprolactam modified bisphenol type epoxy resin, polyvinylcyclohexene diepoxide, “Epicoat 828”, “Epicoat 1001”, “Epicoat 1002” ”,“ Epicoat 1004 ”,“ Epicoat 1007 ”and“ Epicoat 1009 ”(all manufactured by Shell, bisphenol A type epoxy resin).

  The blending ratio of the curing agent is preferably in the range of 0.001 to 2, more preferably 0.01 to 1.5 average functional groups in the curing agent per hydroxyl group in the starch. When the average is less than 0.001, the film performance such as water resistance is deteriorated. On the other hand, when the average is more than 2, the biodegradability is deteriorated.

  For the modified starch containing acid groups, a cured product can be obtained by blending a curing agent such as polyepoxide.

  In the modified starch used in the present invention, the modified starch having an isocyanate group (which may be blocked) in the starch molecule will be described below.

Examples of the starch containing an isocyanate group (which may be blocked) include those represented by the following structural formula.
6

In the formula, R ₇ is a residue of an isocyanate group-containing polyisocyanate compound that has reacted with a hydroxyl group of starch (may be blocked). D is a hydroxyl group, —OOR ₁ , —OOR ₆ , —OOR ₇ , —OOR ₈ , —OOR ₉ , or —OOR ₁₀ . Incidentally, the _{-OOR 1, -OOR 6, -OOR 7} , -OOR 8, for -OOR _9, and -OOR ₁₀ have the same meanings as those hereinbefore or hereinafter.

  A blocked isocyanate group or an isocyanate group can form a cured coating film in combination with a hydroxyl group-containing compound (in particular, a biodegradable resin is preferably starch or cellulose).

  The degree of substitution of the blocked isocyanate group and the isocyanate group is 0.01 to 2.5, particularly 0.1 to 2.0.

  When the degree of substitution is less than 0.01, the reactivity is inferior, and when it exceeds 2.5, the coating film performance is inferior.

  As the isocyanate group-containing polyisocyanate compound, the same polyisocyanate compound as described above (which may be blocked) having a hydroxyl group of starch and a curing agent having a functional group that reacts with the hydroxyl group can be used.

  In this manner, an isocyanate group or the like (which may be blocked) is introduced through a urethane bond by the reaction between the hydroxyl group in the starch molecule and the reactive compound.

  For the modified starch containing an isocyanate group (which may be blocked), a curing agent such as a polyol compound or a polyol resin (such as an acrylic polyol, a polyester polyol, a silicone polyol, or a starch) can be blended.

  The blending ratio of the curing agent is preferably in the range of 0.001 to 2, more preferably 0.01 to 1.5 average functional groups in the curing agent per hydroxyl group in the starch. When the average is less than 0.001, the film performance such as water resistance is deteriorated. On the other hand, when the average is more than 2, the biodegradability is deteriorated.

  In the modified starch used in the present invention, a modified starch having an oxidative polymerizable group in the starch molecule will be described below.

  Examples of the starch containing an oxidatively polymerizable group include those represented by the following structural formula.

  The oxidatively polymerizable group is a group such as a non-conjugated double bond or a conjugated double bond. For example, a cured coating film can be formed by blending a polymerization catalyst and leaving it in the air.

  The degree of substitution of the oxidatively polymerizable group is 0.01 to 2.5, particularly 0.1 to 2.0.

  When the degree of substitution is less than 0.01, the reactivity is inferior, and when it exceeds 2.5, the coating film performance is inferior.

  7

In the formula, R8 is a residue of an acid group and an oxidative polymerizable group-containing compound reacted with a hydroxyl group of starch. B has the same meaning as described above. E is a hydroxyl group, —OOR ₁ , —OOR ₆ , —OOR ₇ , —OOR ₈ , —OOR ₉ , or —OOR ₁₀ . Incidentally, the _{-OOR 1, -OOR 6, -OOR 7} , -OOR 8, for -OOR _9, and -OOR ₁₀ have the same meanings as those hereinbefore or hereinafter.

  Specifically, the acid group and oxidatively polymerizable group-containing compound conventionally contains an unsaturated fatty acid that is crosslinked by air oxidative polymerization as a curing component. The content of the oxidative polymerizable group is preferably in the range of 35 to 90 in terms of iodine value. When the iodine value is less than 30, the oxidative polymerization ability becomes insufficient and the curability is deteriorated. Conversely, when the iodine value exceeds 100, the storage stability of the modified starch is deteriorated.

  As the unsaturated fatty acid, any natural or synthetic unsaturated fatty acid can be used, for example, an unsaturated fatty acid obtained from tung oil, linseed oil, castor oil, dehydrated castor oil, safflower oil, tall oil, soybean oil, coconut oil. Saturated fatty acids are mentioned.

  In this way, an oxidatively polymerizable group and the like are introduced through an ester bond by the reaction between the hydroxyl group in the starch molecule and the reactive compound.

  A desiccant can be blended in the modified starch. Specific examples include metal soaps such as cobalt salts, manganese salts, zirconium salts, calcium salts, iron salts, lead salts using aliphatic carboxylic acids such as oleic acid and alicyclic carboxylic acids such as naphthenic acid as a carrier. be able to.

  The blending ratio of the desiccant is 0.001 to 20 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the modified starch. When the amount is less than 0.001 part by weight, the coating performance such as water resistance is deteriorated. On the other hand, when the amount exceeds 20 parts by weight, the biodegradability is deteriorated.

  In the modified starch used in the present invention, the modified starch having a radical polymerizable group in the starch molecule is described below.

  As a starch containing a radically polymerizable group, what is shown by the following structural formula is mentioned, for example.

  8

In the formula, R ₉ is a residue of a reactive group having a functional group that reacts with a hydroxyl group of starch and a radical polymerizable group-containing compound. Examples of the reactive group include a carboxyl group and an isocyanate group. G is a hydroxyl group, —OOR ₁ , —OOR ₆ , —OOR ₇ , —OOR ₈ , —OOR ₉ , or —OOR ₁₀ . Incidentally, the _{-OOR 1, -OOR 6, -OOR 7} , -OOR 8, for -OOR _9, and -OOR ₁₀ have the same meanings as those hereinbefore or hereinafter.

  Radical polymerizable unsaturated groups include, for example, radical polymerizable unsaturated groups such as vinyl, acryloyl, methacryloyl, and styryl groups. For example, curing catalysts (peroxide catalysts, etc.) and active energy rays (radiation) , Ultraviolet light, visible light, etc.).

  The radically polymerizable unsaturated group has a substitution degree of 0.01 to 2.5, particularly 0.1 to 2.0.

  When the degree of substitution is less than 0.01, the reactivity is inferior, and when it exceeds 2.5, the coating film performance is inferior.

  Specific examples of the radical-polymerizable group-containing compound include acrylic acid, methacrylic acid, N-methylolacrylamide, N-methylolmethacrylamide, N-butoxymethylacrylamide, acrylic isocyanate, acrylic methacrylate, vinyltrimethoxysilane, And monomers such as vinyltris (methoxyethoxy) silane, γ-methacryloyloxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

  Also, functional groups that react with hydroxyl groups on resins such as urethane resins, acrylic resins, alkyd resins, polyester resins, silicone resins, fluororesins, spirane resins, polyether resins, and epoxy resins (for example, isocyanate, anhydride groups, carboxyl groups) Etc.) and a reactive group radical polymerizable unsaturated group introduced resin can also be used. Examples of the radical polymerizable unsaturated group include a vinyl group, a (meth) acryloyl group, a styryl group, and a maleic acid group.

    In this way, radically polymerizable unsaturated groups and the like are introduced through ester bonds and urethane bonds by the reaction between the hydroxyl groups in the starch molecules and the reactive compounds.

  A polymerization catalyst can be blended with the modified starch. Specific examples include peroxides such as benzoyl peroxide.

  The blending ratio of the polymerization catalyst is 0.001 to 20 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the modified starch. When the amount is less than 0.001 part by weight, the coating performance such as water resistance is deteriorated.

  In the modified starch used in the present invention, the modified starch having an amide group in the starch molecule will be described below.

  As starch containing an amide group, what is shown by the following structural formula is mentioned, for example.

  9

In the formula, R 10 is a residue of a reactive group having a functional group that reacts with a hydroxyl group of starch and an amide group-containing compound. Examples of the reactive group include a carboxyl group and an amide group. H is a hydroxyl _{group, -OOR 1, -OOR 6, -OOR} 7, -OOR 8, -OOR 9, or -OOR _10. Incidentally, the _{-OOR 1, -OOR 6, -OOR 7} , -OOR 8, for -OOR _9, and -OOR ₁₀ have the same meanings as those hereinbefore or hereinafter.

  The amide group can be used as a cationic water-based paint (including an electrodeposition paint) after being neutralized with an acidic neutralizer (such as acetic acid) and dissolved or dispersed in water. Further, a cured coating film can be formed in combination with a curing agent (polyepoxide, polyacid, etc.) that reacts with an amide group.

  Amide groups have a degree of substitution of 0.01 to 2.5, in particular 0.1 to 2.0.

  When the degree of substitution is less than 0.01, the reactivity is inferior, and when it exceeds 2.5, the coating film performance is inferior.

  Specific examples of the reactive group and amide group-containing compound include primary or primary compounds such as ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminoethylamine, and dimethylaminopropylamine. Secondary polyamines and the like are included.

    In this way, an amino group or the like is introduced through an amide bond by the reaction between the hydroxyl group in the starch molecule and the reactive compound.

  For the modified starch containing an amide group, a curing agent such as the polyepoxide, polycarboxylic acid compound or resin can be blended.

  The blending ratio of the curing agent is preferably in the range of 0.001 to 2, more preferably 0.01 to 1.5 average functional groups in the curing agent per hydroxyl group in the starch. When the average is less than 0.001, the film performance such as water resistance is deteriorated. On the other hand, when the average is more than 2, the biodegradability is deteriorated.

  The degree of substitution in this specification is the average value of substituted hydroxyl groups per starch molecule, the degree of substitution 3 is that all hydroxyl groups in starch are substituted with these groups, and the degree of substitution 0.01 is 100 molecules of starch. It shows that one hydroxyl group in the group is substituted with these groups.

The modified starch used in the present invention is mixed with a biodegradable resin excluding starch and used as the curable starch composition II of the present invention. As the biodegradable resin excluding starch, those described in the above-mentioned curable starch composition II can be used. Moreover, a mixture ratio can also be used in the above-mentioned range.
In the curable starch composition II of the present invention, when the curable starch composition uses an isocyanate group-containing modified starch, a curing agent that reacts with an isocyanate group (for example, a polyol, etc.), Degradable resins, metal complexes and β-diketones, acetoacetic esters, malonic esters, ketones having a hydroxyl group at the β-position, aldehydes having a hydroxyl group at the β-position, and esters having a hydroxyl group at the β-position It is preferable to use a mixture containing the selected blocking agent. As described above, by using a metal complex as a curing catalyst of the isocyanate curable resin composition and further blending a specific blocking agent, an effect excellent in low-temperature curability and coating workability is exhibited.

    The curable starch composition II of the present invention can be used by dissolving or dispersing in an organic solvent solvent or an aqueous solvent. Examples of the organic solvent used in the organic solvent-based paint include aliphatic, aromatic, ester, ether, ester, ketone, alcohol, and mixed solvents thereof.

  The curable starch composition II of the present invention can be used in a solid state.

  When it is solid, it can be used as a powder coating material or a molding material. When used as a powder coating material, for example, the average particle size is preferably in the range of 1 to 150 μm, particularly 2 to 100 μm. Examples of the powder coating method include fluidized immersion coating, electrostatic powder coating, corona, frictional charging coating, and the like.

  Further, in the curable starch composition II of the present invention, the reactive modified starch is an oxidation polymerization curable type (containing an oxidative polymerizable group), a room temperature curable type (containing an oxidative polymerizable group, an amide group, etc.), a thermosetting type ( In the case of curable compositions such as those containing oxidatively polymerizable groups, amide groups, acid groups, radically polymerizable groups, and the like, and active energy ray curable types (containing radically polymerizable groups), depending on the curable type. Thus, it can be cured according to conventionally known curing equipment and curing conditions.

  As an example of curing equipment and curing conditions, in a thermosetting type, for example, a hot air dryer, an infrared dryer, a far infrared dryer, and these can be used in combination.

  In the case of active energy ray curing, the light source is conventionally used, for example, electron beam, ultra-high pressure, high pressure, medium pressure, low pressure mercury lamp, chemical lamp, carbon arc lamp, xenon lamp. , A light source obtained from each light source such as a metal halide lamp, a fluorescent lamp, a tungsten lamp, and sunlight. Examples of the heat ray include a semiconductor laser (830 nm), a YAG laser (1.06 μm), and infrared rays.

  In the curable starch composition II of the present invention, if necessary, for example, additives conventionally added to paints, adhesives and printing, for example, the above-mentioned colorants, extenders, metallic pigments, colored pearl pigments, Fluidity modifier, anti-repellent agent, anti-sagging agent, UV absorber, antioxidant, UV stabilizer, matting agent, polish, preservative, curing accelerator other than the above, curing catalyst other than the above, scratches Inhibitors, antifoaming agents, the above-mentioned solvents and the like can be used without particular limitation.

  In the composition II, like the composition I, a part or all of the starch can be used as a resin used for a coating material, an adhesive material, a printing material, a sheet material, a laminated material, or a molding material.

  The curable starch compositions I and II of the present invention include, for example, electrical components, illuminations, electrical elements, semiconductors, printing, printed circuits, electronic communication, power, etc. Physics such as optical, display, acoustic, control, vending, signal, information recording, etc .; inorganic chemistry, organic chemistry, polymer chemistry, metallurgy, fiber chemistry, metallurgy, Fibers: Separation / mixing relationship, metal processing relationship, plastic processing relationship, printing relationship, container relationship, packaging relationship, etc. processing / transportation; agriculture / fishery relationship, food relationship, fermentation relationship, household goods relationship, health / entertainment relationship, etc. The above-mentioned materials (for example, paint materials, adhesive materials, printing materials, sheet materials, laminated materials, molding materials, etc.) such as mechanical engineering can be used.

  Since the present invention has the configuration described above, the following effects are exhibited.

  1. Effect of improving starch solubility in organic solvents by using starch ester modified with hydrocarbon group as coating resin, effect of improving compatibility when other resins and curing agents are blended The durability of the coating film, such as the water resistance, corrosion resistance, and weather resistance of the coating film, can be improved by imparting hydrophobicity to the coating film properties such as coating film processability.

  2. By giving a reactive group having at least one substituent selected from an acid group, a blocked isocyanate group, an isocyanate group, an oxidation polymerizable group, a radical polymerizable unsaturated group, and an amide group as a modified starch Curing with excellent durability of the coating film such as processability, water resistance, corrosion resistance, and weather resistance by crosslinking the modified starch using a curing agent or catalyst having a functional group that reacts in a complementary manner with this reactive group A coating film can also be formed.

  3. An acid group or an amide group containing an anionic water-based paint (acid group) or a cationic water-based paint (amide) by neutralizing with a basic compound or an acidic compound and dissolving or dispersing in water as necessary. Group).

4. The biodegradable resin excluding starch blended in the present invention is used in combination with starch or modified starch to adjust the biodegradability rate of the curable resin composition of the present invention, the appearance of the film, the performance, etc. Can be improved. In particular, a cellulose resin is preferable as a biodegradable resin excluding starch, and nitrocellulose, which is a nitrate ester of cellulose, is excellent in compatibility with starch and modified starch, so that it can form a coating with excellent appearance, and plastic. It is preferable to use this material because it has excellent properties such as adhesion to materials such as, durability, and recoatability.
5. The metal complex and the specific blocking agent blended in the present invention satisfy the conflicting properties of low temperature curability and pot life (coating workability) in the isocyanate curable resin composition.

The present invention will be described in detail with reference to examples. In addition, this invention is not limited to the following Example.

Production Example 1 (Modified starch resin 1)
25 g of high amylose corn starch (hydroxyl value 500 mg KOH / g, peak molecular weight 4000) is suspended in 200 g of dimethyl sulfoxide (DMSO), heated to 90 ° C. with stirring, and held at that temperature for 20 minutes for gelatinization. To this solution, 20 g of sodium bicarbonate was added as a catalyst, 7 g of vinyl laurate (C ₁₂ ) was added while maintaining the temperature at 90 ° C., and the mixture was reacted at that temperature for 1 hour. Next, 15 g of vinyl acetate (C ₂ ) is further added and reacted at 80 ° C. for 1 hour. Thereafter, the reaction solution is poured into tap water, stirred and pulverized at high speed, filtered, dehydrated and dried, and then 40 g of this is dissolved in 60 g of methyl ethyl ketone to obtain an esterified starch resin 1 having a nonvolatile content of 40% by weight. It was. The starch-substituted derivative B had a hydroxyl value of 140 mgKOH / g and an aliphatic substitution degree of about 1.

Production Example 2 (Modified starch resin 2)
Esterified starch (manufactured by Nippon Corn Starch Co., Ltd., trade name, CP7CLL, hydroxyl value 90 mgKOH / g, Tg 89 ° C. measured by DSC, peak molecular weight 140000) 30 g was dissolved in 70 g of butyl acetate to obtain a solid content of 30% by weight. It was.

Production Example 3 (Biodegradable resin 1)
Nitrocellulose (manufactured by SNP Japan Co., Ltd., trade name HIG2, nitrogen content 11.5%, acid content 0.03 or less, water content 4% or less, viscosity 2.0 {measured by dissolving 12.2% solid content in butyl acetate}, (Non-volatile content: 70%) 43 g was dissolved in 57 g of butyl acetate to obtain a solid content of 20% by weight.

Production Example 4 (Biodegradable resin 2)
Nitrocellulose (manufactured by SNP Japan Co., Ltd., trade name HIG7, nitrogen content 11.5%, acid content 0.03 or less, moisture 4% or less, viscosity 6.5 {measured by dissolving 12.2% solid content in butyl acetate}, (Non-volatile content: 70%) 43 g was dissolved in butyl acetate (57 g) to obtain a solid content of about 20% by weight.

Example 1
150 g of starch resin 1, 150 g of biodegradable resin 1, 25 g of tolylene diisocyanate, 5 g of acetylacetone (blocking agent) and 10 g of K-KAT XC-5218 were diluted with 26.7 g of butyl acetate to obtain a solid content of about 30% by weight of the curable resin composition 1 of Example 1 was produced.

Examples 2-9
In the same manner as in Example 1, curable resin compositions 2 to 9 having a solid content of 30% by weight were produced according to the formulation shown in Table 1.

Comparative Example 1
A curable resin composition of a comparative example was produced in the same manner as in Example 2 except that the curing catalyst was changed to 0.1 g of dibutyltin dilaurate in Example 2.

Comparative Example 2
In Example 2, the curable resin composition of Comparative Example 2 was produced in the same manner as Example 2 except that acetylacetone was omitted.

Comparative Example 3
A curable resin composition of Comparative Example 3 was produced in the same manner as in Example 2 except that the biodegradable resin 1 was omitted in Example 2.
The formulation is shown in Table 1.

The raw materials described in Table 1 have the following meanings.
TDI: tolylene diisocyanate HMDI system: trimer of hexamethylene diisocyanate LTI: lysine triisocyanate aluminum chelate: aluminum trisacetylacetonate ALCH: aluminum ethyl acetoacetate diisopropylate
K-KAT XC-5218: King Industry, INC, Products, Trade Name, Aluminum Complex Type Catalyst
K-KATXC-6212: King Industry INC, product, trade name, zirconium complex type catalyst DBTDL: dibutyltin dilaurate Test results of Examples and Comparative Examples are listed in Table 2.
The test conditions in Table 2 are as follows.

  Pot life: The above resin composition was hermetically stored in a constant temperature room at 30 ° C., and the time until it thickened and became pudding was examined.

Paint board creation:
Paint plate A: The above-mentioned resin composition is applied to the zinc phosphate-treated steel plate by air spray coating so that the dry film thickness is about 30 μm, and heat-cured so that the plate temperature is maintained at 60 ° C. for 30 minutes. A painted substrate was prepared.

  Test plate B: The above resin composition was applied to an ABS resin plate by air spraying so that the dry film thickness was about 30 μm, and heat-cured so that the plate temperature was maintained at 60 ° C. for 30 minutes, and then the coating base Made the material.

  Coating appearance: The gloss and smoothness of the coating surface were evaluated. ○: Good, Δ: Inferior without gloss, ×: Inferior gloss and smoothness.

Curability: A gauze impregnated with an acetone solvent on the surface of the coating film was wiped off with a fingertip, and evaluation was performed by the number of times the gloss decreased (once in one reciprocation).
Pencil hardness: An evaluation was performed based on pencil scratch hardness (scratches and jade) defined in JIS K-5500-5-4.

Adhesiveness: Evaluation based on adhesiveness (cross cut) defined in JIS K-5500-5-6 was performed. The cross cut interval was 1 mm. The classification of the test results was performed in five stages from 0 (good without peeling) to 4 (poor when the peeled area was 55% or more) according to the regulations.
The results are shown in Table 2.

The curable starch composition of the present invention can be used for pot life, curability, and plastic coating.

Claims (6)

A curable starch composition comprising a starch, a curing agent having a functional group that reacts complementarily with at least one hydroxyl group contained in the starch molecule, and a biodegradable resin excluding the starch. . The curable starch composition is starch, polyisocyanate curing agent, biodegradable resin excluding starch, metal complex and β-diketone, acetoacetate ester, malonate ester, ketone having a hydroxyl group at β-position, The curable starch composition according to claim 1, comprising a blocking agent selected from aldehydes having a hydroxyl group at the β-position and esters having a hydroxyl group at the β-position. Excluding modified starch and starch having at least one substituent selected from a hydrocarbon group, an acid group, a blocked isocyanate group, an isocyanate group, an oxidation polymerizable group, a radical polymerizable unsaturated group and an amide group in the starch molecule A curable starch composition, which is a mixture with a biodegradable resin. The curable starch composition is an isocyanate group-containing modified starch, a curing agent that reacts with an isocyanate group, a biodegradable resin excluding starch, a metal complex and a β-diketone, an acetoacetate, a malonate, a β-position The curable starch composition according to claim 3, comprising a blocking agent selected from ketones having a hydroxyl group, aldehydes having a hydroxyl group at the β-position, and esters having a hydroxyl group at the β-position. The curable starch composition according to any one of claims 1 to 4, wherein the biodegradable resin excluding starch is a fiber-based resin. The curable starch composition according to any one of claims 1 to 5, wherein the fiber-based resin is nitrocellulose.