JP7567480B2 - Urethane resin composition, surface treatment agent, and article - Google Patents

Description

The present invention relates to a urethane resin composition, a surface treatment agent, and an article having a layer made of the surface treatment agent.

In the manufacturing process of TPO (thermoplastic olefin) leather seats for automobile interiors, the surface is finished with a surface treatment agent from the viewpoint of imparting durability and design. The materials used in conventional surface treatment agents have mainly been solvent-based resin compositions containing organic solvents, but in response to the increasing environmental regulations in recent years, water-based surface treatment agents that are substantially free of organic solvents are being developed.

As an example of the aqueous surface treatment agent, a method of overpainting two types of urethane resin compositions containing water has been disclosed (see, for example, Patent Document 1). Although this method provides excellent abrasion resistance, the adhesion to TPO is insufficient.

It has been pointed out that when surface treatment agents are made water-based, they have inferior adhesion to TPO compared to conventional solvent-based resin compositions.

JP 2006-176615 A

The problem that the present invention aims to solve is to provide a water-containing urethane resin composition that has excellent adhesion to thermoplastic olefin (TPO) sheets.

The present invention provides a urethane resin composition comprising a urethane resin (A), an olefin resin (B), water (C), and an adhesion imparting agent (D) having a number average molecular weight of 300 or more.

The present invention also provides a surface treatment agent that contains the urethane resin composition, and an article that has a layer formed from the surface treatment agent.

The urethane resin composition of the present invention has excellent adhesion to TPO sheets (hereinafter abbreviated as "TPO adhesion"). In addition, the urethane resin composition of the present invention contains water and is an environmentally friendly material.

The urethane resin composition of the present invention contains a urethane resin (A), an olefin resin (B), water (C), and a specific adhesion imparting agent (D).

The urethane resin (A) is dispersible in water (C), and examples of such resins include urethane resins having hydrophilic groups such as anionic groups, cationic groups, and nonionic groups; urethane resins forcibly dispersed in water (B) using an emulsifier, etc. These urethane resins (A) may be used alone or in combination of two or more.

An example of a method for obtaining a urethane resin having an anionic group is to use, as a raw material, one or more compounds selected from the group consisting of compounds having a carboxyl group and compounds having a sulfonyl group.

Examples of compounds having a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpropionic acid, and 2,2-valeric acid. These compounds may be used alone or in combination of two or more.

Examples of compounds having a sulfonyl group that can be used include 3,4-diaminobutanesulfonic acid, 3,6-diamino-2-toluenesulfonic acid, 2,6-diaminobenzenesulfonic acid, N-(2-aminoethyl)-2-aminoethylsulfonic acid, etc. These compounds may be used alone or in combination of two or more.

The carboxyl and sulfonyl groups may be partially or completely neutralized with a basic compound in the resin composition. Examples of the basic compound include organic amines such as ammonia, triethylamine, pyridine, and morpholine; alkanolamines such as monoethanolamine and dimethylethanolamine; and metal base compounds including sodium, potassium, lithium, and calcium.

One method for obtaining the urethane resin having the cationic group is, for example, to use one or more compounds having an amino group as raw materials.

Examples of the compound having an amino group include compounds having primary and secondary amino groups, such as triethylenetetramine and diethylenetriamine; compounds having a tertiary amino group, such as N-alkyldialkanolamines, such as N-methyldiethanolamine and N-ethyldiethanolamine, and N-alkyldiaminoalkylamines, such as N-methyldiaminoethylamine and N-ethyldiaminoethylamine. These compounds may be used alone or in combination of two or more.

One method for obtaining the urethane resin having a nonionic group is, for example, to use one or more compounds having an oxyethylene structure as raw materials.

As the compound having an oxyethylene structure, for example, polyether polyols having an oxyethylene structure such as polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, etc. can be used. These compounds may be used alone or in combination of two or more.

The amount of raw materials used to produce the urethane resin having the above hydrophilic groups is preferably in the range of 0.1 to 15 mass% of the raw materials for urethane resin (A), more preferably in the range of 1 to 10 mass%, and even more preferably in the range of 1.5 to 7 mass%, in order to obtain even better chemical resistance, abrasion resistance, weather resistance, and hydrolysis resistance.

Examples of emulsifiers that can be used to obtain the urethane resin that is forcibly dispersed in water (C) include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitol tetraoleate, and polyoxyethylene-polyoxypropylene copolymers; anionic emulsifiers such as fatty acid salts such as sodium oleate, alkyl sulfate ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkanesulfonates, and sodium alkyldiphenyl ether sulfonates; and cationic emulsifiers such as alkylamine salts, alkyltrimethylammonium salts, and alkyldimethylbenzylammonium salts. These emulsifiers may be used alone or in combination of two or more.

Specifically, the urethane resin (A) may be, for example, a reaction product of the raw materials used to produce the urethane resin having hydrophilic groups described above, polyisocyanate (a1), polyol (a2), and chain extender (a3). These reactions may be performed using known urethane reactions.

As the polyisocyanate (a1), for example, aromatic polyisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimidized diphenylmethane polyisocyanate; aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more.

As the polyisocyanate (a1), it is preferable to use an alicyclic polyisocyanate from the viewpoint of obtaining even better chemical resistance, abrasion resistance, and weather resistance, and it is more preferable to use a polyisocyanate having at least one structure in which the nitrogen atom of the isocyanate group is directly linked to a cyclohexane ring, and it is even more preferable to use isophorone diisocyanate and/or dicyclohexylmethane diisocyanate, and it is more preferable to use isophorone diamine from the viewpoint of further improving processability during stretching. In addition, the amount of alicyclic polyisocyanate used is preferably 30% by mass or more in polyisocyanate (a1) from the viewpoint of obtaining even better chemical resistance, abrasion resistance, and weather resistance, more preferably 40% by mass or more, and even more preferably 50% by mass or more.

In addition, when the urethane resin composition of the present invention is used as a surface treatment agent, if even greater light resistance and processability during stretching are required, it is preferable to use the alicyclic polyisocyanate and the aliphatic polyisocyanate in combination as the polyisocyanate (a1), and it is preferable to use hexamethylene diisocyanate as the aliphatic polyisocyanate. In this case, the content of the alicyclic polyisocyanate in the polyisocyanate (a1) is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more.

The amount of polyisocyanate (a1) used is preferably in the range of 5 to 50% by mass in the raw material of urethane resin (A), more preferably in the range of 15 to 40% by mass, and even more preferably in the range of 20 to 37% by mass, in order to obtain even better chemical resistance, abrasion resistance, and weather resistance.

As the polyol (a2), for example, polyether polyol, polyester polyol, polyacrylic polyol, polycarbonate polyol, polybutadiene polyol, etc. can be used. These polyols may be used alone or in combination of two or more. Among these, it is preferable to use polycarbonate polyol because it provides even better chemical resistance, abrasion resistance, and weather resistance.

The polycarbonate polyol may be, for example, a reaction product of a carbonate ester and/or phosgene with a compound having two or more hydroxyl groups.

Examples of the carbonate ester that can be used include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and propylene carbonate. These compounds may be used alone or in combination of two or more.

Examples of compounds having two or more hydroxyl groups include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,5-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,8-nonanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, trimethylolpropane, 3-methylpentanediol, neopentyl glycol, trimethylolethane, and glycerin. These compounds may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining even more excellent chemical resistance, abrasion resistance, and weather resistance, it is preferable to use one or more compounds selected from the group consisting of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 3-methylpentanediol, and 1,10-decanediol, and 1,6-hexanediol is more preferable.

The amount of the polycarbonate polyol used is preferably 85% by mass or more in polyol (a2), more preferably 90% by mass or more, and even more preferably 95% by mass or more, in order to obtain even better chemical resistance, abrasion resistance, and weather resistance.

The number average molecular weight of the polycarbonate polyol is preferably in the range of 100 to 100,000, more preferably in the range of 150 to 10,000, and even more preferably in the range of 200 to 2,500, in order to obtain even better chemical resistance, mechanical strength, abrasion resistance, and weather resistance. The number average molecular weight of the polycarbonate polyol is a value measured by gel permeation column chromatography (GPC).

The number average molecular weight of the polyol (a2) other than the polycarbonate polyol is preferably in the range of 500 to 100,000, more preferably in the range of 700 to 50,000, and even more preferably in the range of 800 to 10,000, in order to obtain even better weather resistance. The number average molecular weight of the polyol (a2) is a value measured by gel permeation column chromatography (GPC).

The amount of polyol (a2) used is preferably in the range of 30 to 80 mass% of the raw material of urethane resin (A), more preferably in the range of 40 to 75 mass%, and even more preferably in the range of 50 to 70 mass%.

The chain extender (a3) is, for example, one having a number average molecular weight in the range of 50 to 450 (excluding the polycarbonate polyol). Specific examples of the chain extender (a3) include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,4-cyclohexanediamine, Chain extenders having an amino group, such as Sandiamine and hydrazine, and chain extenders having a hydroxyl group, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, saccharose, methylene glycol, glycerin, sorbitol, bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, and trimethylolpropane, can be used. These chain extenders can be used alone or in combination of two or more.

As the chain extender (a3), among the above, it is preferable to use a chain extender having an amino group, from the viewpoint of obtaining even better chemical resistance, mechanical strength, abrasion resistance, and weather resistance, and piperazine and/or hydrazine are more preferable. The total amount of piperazine and hydrazine in the chain extender (a3) is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 80% by mass or more. In addition, it is preferable that the chain extender (a3) has an average functional group number of less than 3, more preferably less than 2.5. In addition,

The amount of the chain extender (a3) used is preferably in the range of 0.5 to 10 mass% of the raw material urethane resin (A), more preferably in the range of 0.7 to 5 mass%, and even more preferably in the range of 0.9 to 2.3, in order to obtain even better chemical resistance, mechanical strength, abrasion resistance, and weather resistance.

Examples of the method for producing the urethane resin (A) include a method in which the polyisocyanate (a1), the polyol (a2), and the raw materials used to produce the urethane resin having a hydrophilic group are reacted to produce a urethane prepolymer having an isocyanate group, and then the urethane prepolymer is reacted with the chain extender (a3); and a method in which the polyisocyanate (a1), the polyol (a2), the raw materials used to produce the urethane resin having a hydrophilic group, and the chain extender (a3) are charged all at once and reacted. These reactions can be carried out, for example, at 50 to 100°C for 3 to 10 hours.

The molar ratio of the sum of the hydroxyl groups of the raw materials used to produce the urethane resin having hydrophilic groups, the hydroxyl groups of the polyol (a2), and the hydroxyl groups and amino groups of the chain extender (a3) to the isocyanate groups of the polyisocyanate (a1) [(isocyanate groups)/(hydroxyl groups and amino groups)] is preferably in the range of 0.8 to 1.2, and more preferably in the range of 0.9 to 1.1.

When producing the urethane resin (A), it is preferable to deactivate the isocyanate groups remaining in the urethane resin (A). When deactivating the isocyanate groups, it is preferable to use an alcohol having one hydroxyl group, such as methanol. The amount of the alcohol used is preferably in the range of 0.001 to 10 parts by mass per 100 parts by mass of the urethane resin (A).

In addition, an organic solvent may be used when producing the urethane resin (A). Examples of the organic solvent that can be used include ketone compounds such as acetone and methyl ethyl ketone; ether compounds such as tetrahydrofuran and dioxane; acetate compounds such as ethyl acetate and butyl acetate; nitrile compounds such as acetonitrile; and amide compounds such as dimethylformamide and N-methylpyrrolidone. These organic solvents may be used alone or in combination of two or more. It is preferable that the organic solvent is finally removed by distillation or the like.

The content of urethane bonds in the urethane resin (A) is preferably in the range of 980 to 4,000 mmol/kg, more preferably in the range of 1,000 to 3,500 mmol/kg, even more preferably in the range of 1,100 to 3,000 mmol/kg, and even more preferably in the range of 1,150 to 2,500 mmol/kg, in order to obtain even better chemical resistance, abrasion resistance, and weather resistance. The content of urethane bonds in the urethane resin (A) is a value calculated from the amounts of the polyisocyanate (a1), polyol (a2), raw materials used to produce the urethane resin having a hydrophilic group, and chain extender (a3) charged.

The content of urea bonds in the urethane resin (A) is preferably in the range of 315 to 850 mmol/kg, more preferably in the range of 350 to 830 mmol/kg, even more preferably in the range of 400 to 800 mmol/kg, and even more preferably in the range of 410 to 770 mmol/kg, in order to obtain even better chemical resistance, abrasion resistance, and weather resistance. The content of urea bonds in the urethane resin (A) is a value calculated from the amounts of the polyisocyanate (a1), polyol (a2), raw materials used to produce the urethane resin having a hydrophilic group, and chain extender (a3) charged.

The content of the alicyclic structure in the urethane resin (A) is preferably in the range of 500 to 3,000 mmol/kg, more preferably in the range of 600 to 2,900 mmol/kg, and even more preferably in the range of 700 to 2,700 mmol/kg, in order to obtain even better chemical resistance, abrasion resistance, and weather resistance. The content of the alicyclic structure in the urethane resin (A) is a value calculated from the amounts of the polyisocyanate (a1), polyol (a2), raw materials used to produce the urethane resin having a hydrophilic group, and chain extender (a3) charged.

From the standpoints of coatability, workability and storage stability, the content of the urethane resin (A) is preferably in the range of 1 to 30 mass% in the urethane resin composition, and more preferably in the range of 2 to 20 mass%.

The olefin resin (B) is used for the purpose of improving TPO adhesion. Examples of the olefin resin (B) that can be used include polyolefins obtained by polymerizing polyolefin compounds; natural rubber, ethylene-vinyl acetate copolymers, synthetic isopropylene rubber; and modified products thereof. These olefin resins may be used alone or in combination of two or more.

As the polyolefin compound, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, etc. can be used. These olefin compounds may be used alone or in combination of two or more. The polyolefin may be a homopolymer or a copolymer.

As the modified polyolefin, for example, polyolefin modified with a hydroxyl group, polyolefin modified with an acid, polyolefin modified with an amino group, etc. can be used. These polyolefins may be used alone or in combination of two or more. Among these, it is preferable to use an acid-modified polyolefin, since it is possible to further improve the TPO adhesion.

As the acid-modified polyolefin, for example, a polyolefin that has been acid-modified without chlorination can be used. For the acid modification, a method of reacting an unsaturated carboxylic acid or an anhydride thereof with a polyolefin is preferable. As the unsaturated carboxylic acid, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, aconitic acid, crotonic acid; anhydrides thereof; half esters and half amides of unsaturated carboxylic acids can be used. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use one or more selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, and maleic anhydride.

In addition, it is preferable to use an acid-modified polyolefin having a polyether chain because it has excellent dispersibility in water, and the polyether chain is preferably a polyethylene chain and/or a polypropylene chain, and more preferably a polyethylene chain.

The weight average molecular weight of the olefin resin (B) is preferably in the range of 10,000 to 500,000, and more preferably in the range of 20,000 to 200,000, in order to obtain even better TPO adhesion. The weight average molecular weight of the olefin resin (B) is a value measured by gel permeation column chromatography (GPC).

The content of the olefin resin (B) is preferably in the range of 0.01 to 10 mass%, and more preferably in the range of 0.1 to 7 mass%, in order to obtain even better TPO adhesion.

In addition, the amount of the olefin resin (B) used per 100 parts by mass of the urethane resin (A) (= solid content) is preferably in the range of 1 to 60 parts by mass, and more preferably in the range of 2 to 50 parts by mass.

The water (C) may be ion-exchanged water, distilled water, etc. The content of the water (C) in the urethane resin composition is preferably in the range of 30 to 95% by mass, more preferably 40 to 90% by mass, from the viewpoints of the coatability, workability, and storage stability of the urethane resin composition.

In order to obtain excellent TPO adhesion, it is essential that the adhesion imparting agent (D) has a number average molecular weight of 300 or more. In order to obtain even better TPO adhesion, the number average molecular weight of the adhesion imparting agent is preferably in the range of 400 to 10,000, more preferably in the range of 450 to 4,000, and even more preferably in the range of 500 to 1,000. Note that the number average molecular weight of the adhesion imparting agent (D) is shown in the case where it can be calculated from the chemical formula, and in other cases, the value is shown as measured by gel permeation column chromatography (GPC).

As the adhesion imparting agent (D), for example, a polymer having an acid group, a polymer having an acid group, a polymer having a functional group, etc. can be used. These adhesion imparting agents may be used alone or in combination of two or more. Among these, it is preferable to use a polymer having an acid group, since even better TPO adhesion can be obtained.

Examples of the polymer having an acid group that can be used include polyester having an acid group, acrylic polymer having an acid group, styrene polymer having an acid group, styrene-isoprene polymer having an acid group, styrene-butadiene polymer having an acid group, etc. These polymers may be used alone or in combination of two or more. Among these, it is preferable to use polyester having an acid group because it has good affinity for water (C) and storage stability, and can provide even better TPO adhesion.

The polyester having an acid group can be, for example, a reaction product of a compound having two or more hydroxyl groups with a polybasic acid.

Examples of compounds having two or more hydroxyl groups include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, 1,3-butanediol, 2,2-diethyl-1,3-propanediol, 2,2-diethylpropanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, trimethylolethane, trimethylolpropane, and pentaerythritol. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use a compound having 2 to 3 hydroxyl groups, and it is more preferable to use a compound having 3 hydroxyl groups, in order to obtain even better adhesion to PVC.

Examples of the polybasic acid include aliphatic polybasic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, dodecanedioic acid, and azelaic acid; polybasic acids having unsaturated groups such as citraconic acid, itaconic acid, citraconic anhydride, and itaconic anhydride; and aromatic polybasic acids such as orthophthalic acid, isophthalic acid, terephthalic acid, and phthalic anhydride. These polybasic acids may be used alone or in combination of two or more. Among these, it is preferable to use aliphatic polybasic acids because they provide even better adhesion to PVC.

The acid value of the polymer having acid groups is preferably in the range of 10 to 70 mgKOH/g, more preferably in the range of 15 to 40 mgKOH/g, in order to obtain even better TPO adhesion. The acid value of the polymer having acid groups is a value measured by potentiometric titration in accordance with JIS K0070-1992.

The adhesion imparting agent (D) may contain other components such as a solvent and a neutralizing agent as necessary. Among these, it is preferable to contain a neutralizing agent, since this further improves the affinity for water (C) and the storage stability.

Examples of the solvent that can be used include 1-methoxy-2-hydroxypropane, 1-methoxy-2-propyl acetate, dipropylene glycol monomethyl ether, 2,2,4-trimethyl-3-hydroxyethyl isobutyrate, methanol, ethanol, propanol, butanol, diacetone alcohol, diacetone alcohol, dimethyl carbitol, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, propylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, and dimethyl carbonate. These solvents may be used alone or in combination of two or more. When the solvent is used, the content is, for example, in the range of 1 to 30% by mass in the adhesion imparting agent (D).

Examples of the neutralizing agent include non-volatile bases such as sodium hydroxide and potassium hydroxide; tertiary amine compounds such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanol; secondary amine compounds such as dimethylamine, diethylamine, and dibutylamine; primary amine compounds such as ethylenediamine, methylamine, ethylamine, and butylamine; and ammonia. These neutralizing agents may be used alone or in combination of two or more. When the neutralizing agent is used, the content may be, for example, in the range of 0.001 to 3% by mass in the adhesion imparting agent (D).

The content of the adhesion imparting agent (D) is preferably in the range of 0.01 to 20% by mass, and more preferably in the range of 0.1 to 10% by mass, in order to obtain even better TPO adhesion.

In addition, the amount of the adhesion imparting agent (D) used per 100 parts by mass of the urethane resin (A) (= solid content) is preferably in the range of 5 to 100 parts by mass, and more preferably in the range of 10 to 70 parts by mass.

The urethane resin composition of the present invention contains the urethane resin (A), the olefin resin (B), water (C), and the adhesion imparting agent (D) as essential components, but other additives may be used as necessary.

Examples of the other additives that can be used include fillers (E), crosslinking agents (F), emulsifiers, defoamers, leveling agents, thickeners, viscoelasticity regulators, defoamers, wetting agents, dispersants, preservatives, plasticizers, penetrants, fragrances, bactericides, miticides, fungicides, UV absorbers, antioxidants, antistatic agents, flame retardants, dyes, pigments (e.g., titanium white, red iron oxide, phthalocyanine, carbon black, permanent yellow, etc.). These additives may be used alone or in combination of two or more.

As the other additives, when the urethane resin composition of the present invention is used as a surface treatment agent, and when the coating film is used in an application requiring a matte finish, it is preferable to use a filler (E) and a crosslinking agent (F) to improve the mechanical strength of the coating film.

Examples of the filler (E) that can be used include silica particles, organic beads, calcium carbonate, magnesium carbonate, barium carbonate, talc, aluminum hydroxide, calcium sulfate, kaolin, mica, asbestos, mica, calcium silicate, alumina silicate, etc. These fillers may be used alone or in combination of two or more.

As the silica particles, for example, dry silica, wet silica, etc. can be used. Among these, dry silica is preferred because it has a high scattering effect and a wide range of gloss adjustment. The average particle diameter of these silica particles is preferably in the range of 2 to 14 μm, and more preferably in the range of 3 to 12 μm. The average particle diameter of the silica particles refers to the particle diameter when the accumulated amount in the accumulated particle amount curve of the particle size distribution measurement results accounts for 50% (particle diameter at D50 in the particle size distribution).

Examples of the organic beads that can be used include acrylic beads, urethane beads, silicone beads, olefin beads, etc.

When the filler (E) is used, the amount used can be determined appropriately depending on the matte finish to be imparted, but for example, it is preferably in the range of 0.1 to 30 parts by weight, and more preferably in the range of 1 to 10 parts by weight, per 100 parts by weight of the urethane resin (A).

As the crosslinking agent (F), for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a carbodiimide crosslinking agent, an oxazolidine crosslinking agent, an oxazoline crosslinking agent, a melamine crosslinking agent, etc. can be used. These crosslinking agents may be used alone or in combination of two or more.

When the crosslinking agent (F) is used, the amount used is, for example, preferably in the range of 5 to 40 parts by mass, and more preferably in the range of 10 to 30 parts by mass, per 100 parts by mass of the urethane resin (A).

As described above, the urethane resin composition of the present invention provides excellent TPO adhesion. Therefore, the urethane resin composition of the present invention can be suitably used as a surface treatment agent for TPO leather, and can be particularly suitably used for TPO leather.

Next, we will explain TPO leather that has been surface-treated with the surface treatment agent of the present invention.

The TPO leather can be produced, for example, by applying the surface treatment agent onto a TPO sheet, drying it to form a surface treatment layer, and then subjecting it to a stretching process.

Methods for applying the surface treatment agent include, for example, using a bar coater, roll coater, spray coater, knife coater, etc.

One example of a method for carrying out the stretching process is to use a vacuum forming machine. The stretching can be, for example, in the range of 110 to 150%. In the present invention, by using the surface treatment agent, it is possible to obtain TPO leather that is easy to stretch and has excellent TPO adhesion with a single application of the surface treatment agent.

The thickness of the layer formed by the surface treatment agent is, for example, in the range of 0.1 to 100 μm.

The present invention will now be described in more detail using examples.

Synthesis Example 1 Preparation of Urethane Resin (A-1) Aqueous Dispersion Into a four-neck flask equipped with a stirrer, a thermometer, and a nitrogen reflux tube, 250 parts by mass of methyl ethyl ketone and 0.001 parts by mass of stannous octoate were placed, and then 200 parts by mass of polycarbonate polyol-1 (made from 1,4-butanediol and 1,6-hexanediol, number average molecular weight: 1,000), 15 parts by mass of 2,2-dimethylolpropionic acid, 49 parts by mass of isophorone diisocyanate, and 34 parts by mass of hexamethylene diisocyanate were placed and reacted at 70° C. for 1 hour to obtain a methyl ethyl ketone solution of a urethane prepolymer.
Next, 6.8 parts by mass of hydrazine and 15 parts by mass of triethylamine were mixed with the methyl ethyl ketone solution of the urethane prepolymer, and then 820 parts by mass of ion-exchanged water was added to obtain an emulsion in which the urethane resin (A-1) was dispersed in water.
Next, methyl ethyl ketone was distilled off from the emulsion, and ion-exchanged water was further added to obtain an aqueous dispersion of urethane resin (A-1) having a nonvolatile content of 30% by mass.
The resulting urethane resin (A-1) had a urethane bond content of 2,052 mmol/kg, a urea bond content of 698 mmol/kg, and an alicyclic structure content of 715 mmol/kg.

Synthesis Example 2 Preparation of Urethane Resin (A-2) Aqueous Dispersion Into a four-neck flask equipped with a stirrer, a thermometer, and a nitrogen reflux tube, 250 parts by mass of methyl ethyl ketone and 0.001 parts by mass of stannous octoate were placed, and then 220 parts by mass of polycarbonate polyol-3 (made from 1,6-hexanediol, number average molecular weight: 2,000), 12 parts by mass of 2,2-dimethylolpropionic acid, and 70 parts by mass of dicyclohexylmethane diisocyanate were placed and reacted at 70° C. for 1 hour to obtain a methyl ethyl ketone solution of a urethane prepolymer.
Next, 4.5 parts by mass of piperazine and 9 parts by mass of triethylamine were mixed with the methyl ethyl ketone solution of the urethane prepolymer, and then 880 parts by mass of ion-exchanged water was added to obtain an emulsion in which the urethane resin (A-2) was dispersed in water.
Next, methyl ethyl ketone was distilled off from the emulsion, and ion-exchanged water was further added to obtain an aqueous dispersion of urethane resin (A-2) having a nonvolatile content of 32% by mass.
The resulting urethane resin (A-2) had a urethane bond content of 1,278 mmol/kg, a urea bond content of 435 mmol/kg, and an alicyclic structure content of 1,713 mmol/kg.

Synthesis Example 3 Preparation of Urethane Resin (A-3) Aqueous Dispersion Into a four-neck flask equipped with a stirrer, a thermometer, and a nitrogen reflux tube, 250 parts by mass of methyl ethyl ketone and 0.001 parts by mass of stannous octoate were placed, and then 138 parts by mass of polycarbonate polyol-4 (made from 1,6-hexanediol, number average molecular weight: 2,000), 55 parts by mass of polycarbonate polyol-5 (made from 1,6-hexanediol, number average molecular weight: 500), 13 parts by mass of 2,2-dimethylolpropionic acid, and 100 parts by mass of dicyclohexylmethane diisocyanate were placed, and the mixture was allowed to react at 70° C. for 1 hour, to obtain a methyl ethyl ketone solution of a urethane prepolymer.
Next, 5.6 parts by mass of piperazine and 10 parts by mass of triethylamine were mixed with the methyl ethyl ketone solution of the urethane prepolymer, and then 880 parts by mass of ion-exchanged water was added to obtain an emulsion in which the urethane resin (A-3) was dispersed in water.
Next, methyl ethyl ketone was distilled off from the emulsion, and ion-exchanged water was further added to obtain an aqueous dispersion of urethane resin (A-3) having a nonvolatile content of 30% by mass.
The resulting urethane resin (A-3) had a urethane bond content of 1,747 mmol/kg, a urea bond content of 576 mmol/kg, and an alicyclic structure content of 2,341 mmol/kg.

[Example 1]
The aqueous dispersion of the urethane resin (A-1) obtained in Synthesis Example 1 was 26 % by mass, acid-modified non-chlorinated polyolefin ("Arrowbase SD-1010" manufactured by Unitika Ltd., non-volatile content: 20.5% by mass, hereinafter abbreviated as "POf") was 17 % by mass, a carbodiimide compound ("Carbodilite E-04" manufactured by Nisshinbo Chemical Inc., non-volatile content: 40% by mass), silica ("ACEMATT" manufactured by Evonik Degussa A/S) was 2.5% by mass, and the aqueous dispersion of the urethane resin (A-1) obtained in Synthesis Example 1 was 26% by mass, acid-modified non-chlorinated polyolefin ("Arrowbase SD-1010" manufactured by Unitika Ltd., non-volatile content: 20.5% by mass, hereinafter abbreviated as "POf") was 17% by mass, a carbodiimide compound ("Carbodilite E-04" manufactured by Nisshinbo Chemical Inc., non-volatile content: 40% by mass), and silica ("ACEMATT" manufactured by Evonik Degussa A/S). A urethane resin composition was obtained by mixing 2 mass % of "C-3300", silica particles produced by a dry method and having an organically treated surface, average particle size: 9.5 μm, 1 mass % of an adhesion imparting agent (a polyester having an acid group obtained by reacting adipic acid and trimethylolpropane, number average molecular weight: 716, acid value: 30 mgKOH/g, solids content: 80 mass % (also containing 0.5 mass % of a neutralizing agent, dimethylethanolamine, and a solvent, 1-methoxy-2-hydroxypropane), hereinafter abbreviated as "C-1"), and 51.5 mass % of water.

[Example 2]
A urethane resin composition was obtained in the same manner as in Example 1, except that the amount of C-1 used was changed to 3 mass % and the amount of water used was changed to 49.5 mass %.

[Example 3]
A urethane resin composition was obtained in the same manner as in Example 1, except that the amount of C-1 used was changed to 5 mass % and the amount of water used was changed to 47.5 mass %.

[Example 4]
A urethane resin composition was obtained in the same manner as in Example 3, except that the aqueous dispersion of urethane resin (A-2) obtained in Synthesis Example 2 was used instead of the aqueous dispersion of urethane resin (A-1).

[Example 5]
A urethane resin composition was obtained in the same manner as in Example 3, except that the aqueous dispersion of urethane resin (A-3) obtained in Synthesis Example 2 was used instead of the aqueous dispersion of urethane resin (A-1).

A urethane resin composition was obtained in the same manner as in Example 1, except that the amount of C-1 used was changed to 0 mass% and the amount of water used was changed to 52.5 mass%.

[Method for measuring number average molecular weight]
The number average molecular weights of the polyols and adhesion promoters used in the synthesis examples and the like, and the weight average molecular weights of the olefin resins are shown as values measured by gel permeation column chromatography (GPC) under the following conditions.

Measurement device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used, connected in series.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[Method of preparing evaluation samples]
The urethane resin compositions obtained in the Examples and Comparative Examples were mixed, and then coated on a TPO sheet (thickness 0.4 mm) whose surface had been corona-treated using a bar coater No. 14, and then dried at 120° C. for 1 minute to obtain a sample for evaluation.

[Production of vacuum molded products]
The evaluation sample obtained above was vacuum-formed using a vacuum forming machine ("Vacuum Forming Machine Forming 300X" manufactured by Seiko Sangyo Co., Ltd.) so that the area ratio was 130%, and a vacuum-formed product was obtained.

[Evaluation of TPO Adhesion]
A hot melt tape was adhered to the surface treatment layer of the vacuum molded product obtained above at 180° C. for 30 seconds under a pressure of 0.615 kg/cm ² , and the peel strength was measured at a width of 17 mm and evaluated as follows.
"T": 15N/17mm or more "F": less than 15N/17mm

It was found that the urethane resin composition of the present invention has excellent TPO adhesion. In addition, in Examples 1 to 3, stretching processing could be carried out smoothly.

On the other hand, in Comparative Example 1, which does not use adhesion imparting agent (D), the TPO adhesion was poor.

Comparative Example 2 is an embodiment in which an adhesion imparting agent having a number average molecular weight below the range specified in the present invention was used instead of adhesion imparting agent (D), but the TPO adhesion was poor.

Claims (4)

The present invention relates to a urethane resin composition comprising a urethane resin (A), an olefin resin (B), water (C), and an adhesion imparting agent (D), and a filler (E) containing dry silica ,
The olefin resin (B) is an acid-modified polyolefin,
the adhesion imparting agent (D) is a polyester having an acid group and a number average molecular weight of 450 to 4,000;
the content of the olefin resin (B) in the urethane resin composition is within the range of 0.01 to 10 mass %,
the content of the water (C) in the urethane resin composition is in the range of 30 to 95 mass %,
The surface treatment agent, characterized in that the content of the adhesion imparting agent (D) in the urethane resin composition is in the range of 0.01 to 20 mass %. 2. The surface treatment agent according to claim 1, wherein the adhesion imparting agent (D) has an acid value in the range of 10 to 70 mgKOH/g. An article having a layer formed from the surface treatment agent according to claim 1 or 2 . 4. The article according to claim 3, further comprising a layer formed on the thermoplastic olefin sheet using a surface treatment agent.