JP7703846B2 - Water-based urethane resin composition, surface treatment agent, and article - Google Patents

Description

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

In the manufacturing process of leather seats for automobile interiors, the surface is finished with a surface treatment agent from the viewpoint of chemical resistance 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 the above-mentioned aqueous surface treatment agent, for example, an aqueous surface treatment agent containing polyurethane having specific mechanical properties, a carbodiimide-based crosslinking agent, and a filler has been disclosed (for example, see Patent Document 1).

International Publication No. WO 2015/107933

The surface treatment agent described in the above-mentioned Patent Document 1 can impart excellent abrasion resistance to the surface of an article without impairing the flexibility of the article. In addition, since it contains a filler, it is also excellent in expressing a matte design.
From the viewpoint of environmental hormones, there is a demand for a surface treatment agent that does not use raw materials containing specific substances. For example, tin is one of the substances that needs to be addressed from the viewpoint of environmental hormones, and there is a demand for a surface treatment agent that does not contain tin.
However, a raw material containing tin is used as a catalyst in the polyurethane, which is a component of the surface treatment agent described in Patent Document 1, and the urethane resin composition used in the surface treatment agent in Patent Document 1 contains tin.
Therefore, the present inventors produced polyurethane using a non-tin catalyst instead of a tin catalyst, and prepared an aqueous urethane resin composition containing the polyurethane. As a result, it was found that when polyurethane produced using a tin catalyst was used, the filler did not settle, but when a surface treatment agent was made of an aqueous urethane resin composition containing polyurethane produced using a non-tin catalyst, the filler contained in the aqueous urethane resin composition settled, resulting in poor storage stability.

The present invention aims to provide an aqueous urethane resin composition that does not contain tin, can be effectively used as a surface treatment agent without impairing the various properties required of a surface treatment agent, prevents the filler from settling in the aqueous urethane resin composition, and has excellent storage stability.

As a result of extensive research to solve the above problems, the inventors discovered that by adding an inorganic viscosity modifier to an aqueous urethane resin composition, it is possible to obtain an aqueous urethane resin composition with excellent storage stability and without impairing the various properties required of a surface treatment agent, even when polyurethane produced using a non-tin catalyst is added, and the filler does not settle. This led to the completion of the present invention.

That is, the present invention includes the following aspects.
[1] An aqueous urethane resin composition comprising a urethane resin (A) formed using a non-tin catalyst, water (B), and a filler (C), the aqueous urethane resin composition further comprising an inorganic viscosity modifier (D).
[2] The aqueous urethane resin composition according to [1], further comprising a crosslinking agent (E).
[3] The aqueous urethane resin composition according to [1] or [2], wherein the non-tin catalyst is bismuth carboxylate.
[4] The aqueous urethane resin composition according to any one of [1] to [3], wherein the filler (C) is silica.
[5] The aqueous urethane resin composition according to any one of [2] to [4], wherein the crosslinking agent (E) is a carbodiimide-based crosslinking agent.
[6] The aqueous urethane resin composition according to any one of [1] to [5], wherein the inorganic viscosity modifier (D) is selected from the group consisting of montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, mica, and bentonite.
[7] A surface treatment agent comprising the aqueous urethane resin composition according to any one of [1] to [6].
[8] An article having a layer formed by the surface treatment agent according to [7].

The present invention provides a tin-free aqueous urethane resin composition that can be effectively used as a surface treatment agent without impairing the various properties required of a surface treatment agent, and that prevents the settling of fillers in the aqueous urethane resin composition and has excellent storage stability.

The present invention will be described in detail below. Note that the explanation of the components described below is merely an example for explaining the present invention, and the present invention is not limited to these contents.

(Aqueous urethane resin composition)
The aqueous urethane resin composition of the present invention contains a urethane resin (A) formed using a non-tin catalyst, water (B), a filler (C), and an inorganic viscosity modifier (D).
In a preferred embodiment of the aqueous urethane resin composition of the present invention, the aqueous urethane resin composition further contains a crosslinking agent (E).
Each component constituting the aqueous urethane resin composition will be described below.

<Urethane resin (A)>
The urethane resin (A) is formed using a non-tin catalyst.

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

As a method for obtaining a urethane resin having an anionic group, for example, there is a method using one or more compounds selected from the group consisting of compounds having a carboxyl group and compounds having a sulfonyl group as a raw material. In the present invention, it is preferable to use a compound having a carboxyl group as a raw material.

Examples of the compound having a carboxyl group that can be used 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 the compound having a sulfonyl group include 3,4-diaminobutanesulfonic acid, 3,6-diamino-2-toluenesulfonic acid, 2,6-diaminobenzenesulfonic acid, and N-(2-aminoethyl)-2-aminoethylsulfonic acid. 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 that can be used include organic amines such as ammonia, triethylamine, pyridine, and morpholine; alkanolamines such as monoethanolamine and dimethylethanolamine; and metal base compounds containing sodium, potassium, lithium, calcium, and the like.

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

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 the above nonionic group is, for example, to use one or more compounds having an oxyethylene structure as a raw material.

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 above urethane resin having 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 when obtaining the urethane resin that is forcibly dispersed in water (B) 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.

Specific examples of the urethane resin (A) that can be used include the raw materials used to produce the above-mentioned urethane resin having a hydrophilic group, that is, the reaction product of polyisocyanate (a1), polyol (a2), and chain extender (a3). These reactions can be carried out 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. In addition, the amount of the alicyclic polyisocyanate used is preferably 30% by mass or more in the polyisocyanate (a1), more preferably 40% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of obtaining even better chemical resistance, abrasion resistance, and weather resistance.

When the aqueous urethane resin composition of the present invention is used as a surface treatment agent and even greater light resistance is 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 the polyisocyanate (a1) used is preferably in the range of 5 to 50% by mass in the raw material of the 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.

As the carbonate ester, for example, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, etc. can be used. These compounds may be used alone or in combination of two or more kinds.

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 the terminal group quantitative method.

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 the terminal group quantitative analysis method.

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

Examples of the chain extender (a3) include those having a number average molecular weight in the range of 50 to 450 (excluding the polycarbonate polyols). 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, and piperazine and/or hydrazine are more preferable, since even better chemical resistance, mechanical strength, abrasion resistance, and weather resistance can be obtained. 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, the chain extender (a3) preferably has an average functional group number of less than 3, and more preferably less than 2.5.

The amount of the chain extender (a3) used is preferably in the range of 0.5 to 10% by mass in the raw material of the urethane resin (A), more preferably in the range of 0.7 to 5% by 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 hydrophilic groups are reacted to produce a urethane prepolymer having isocyanate groups, 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 hydrophilic groups, 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 [(isocyanate group)/(hydroxyl group and amino group)] of the sum of the hydroxyl groups of the raw materials used to produce the urethane resin having the 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) 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 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 urethane resin (A).

When producing the urethane resin (A), an organic solvent may be used. 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 kinds. It is preferable that the organic solvent is finally removed by a method such as distillation.

A catalyst is used in the production of the urethane resin (A), but in the present invention, a tin catalyst is not used.
In the present invention, the urethane resin (A) is produced using a non-tin catalyst.
The non-tin catalyst is not particularly limited and can be used appropriately depending on the purpose, and examples thereof include bismuth carboxylate, bismuth halide, bismuth phosphate, bismuth nitrate, bismuth sulfate, etc. Among them, from the viewpoint of miscibility and reactivity, it is preferable to use a non-tin catalyst of bismuth carboxylate such as bismuth octoate, bismuth neodecanoate, bismuth naphthenate, etc.

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 particularly 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), the polyol (a2), the raw materials used to produce the urethane resin having the hydrophilic group, and the chain extender (a3).

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

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), the polyol (a2), the raw materials used to produce the urethane resin having the hydrophilic group, and the chain extender (a3).

From the viewpoints of coatability, workability, and storage stability, the content of urethane resin (A) in the aqueous urethane resin composition is preferably in the range of 3 to 50 mass%, and more preferably in the range of 5 to 30 mass%.

The urethane resin (A) according to the present invention is preferably an acidic urethane resin.

<Water (B)>
As the water (B), ion-exchanged water, distilled water, tap water, purified and sterilized industrial water, well water, etc. can be used.
The content of water (B) in the aqueous urethane resin composition is preferably in the range of 30 to 95 mass %, and more preferably in the range of 50 to 90 mass %, from the viewpoints of the coatability, workability, and storage stability of the aqueous urethane resin composition.

<Filler (C)>
In order that the aqueous urethane resin composition of the present invention may be effectively used as a surface treatment agent, the aqueous urethane resin composition contains a filler (C) in order to impart a matte finish to the coating film.

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

As the silica, 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 size 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 size of the silica particles refers to the particle size when the cumulative amount in the cumulative particle amount curve of the particle size distribution measurement results is 50% (particle size at D50 in the particle size distribution).

Examples of organic beads that can be used include acrylic beads, urethane beads, silicon beads, and olefin beads.

The filler (C) according to the present invention is preferably a filler whose surface is basic or weakly basic.

The amount of filler (C) used can be determined appropriately depending on the matte feel to be imparted, but for example, it is preferably in the range of 0.1 to 10 mass % of the aqueous urethane resin composition, and more preferably in the range of 0.2 to 5 mass %.

<Inorganic Viscosity Modifier (D)>
The aqueous urethane resin composition contains an inorganic viscosity modifier (D) so that the filler does not settle and the aqueous urethane resin composition has excellent storage stability even when the aqueous urethane resin composition contains polyurethane produced using a non-tin catalyst. The inorganic viscosity modifier (D) has an effect as a thickener.

Examples of the inorganic viscosity modifier (D) include montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, mica, and bentonite, etc. These may be used alone or in combination of two or more kinds.
The inorganic viscosity modifier (D) may be any of natural products, synthetic products, products processed with organic substances, etc. Also, those diluted with a diluting medium such as an organic solvent or water may be used.
Among these, synthetic hectorite is preferably used from the viewpoint of less coloration.

In many cases, the inorganic viscosity modifier (D) is effective in terms of storage stability even in small amounts, but the content may be adjusted taking into consideration coatability, workability, etc. The content of the inorganic viscosity modifier (D) is preferably in the range of 0.01 to 1 mass % in the aqueous urethane resin composition, and more preferably in the range of 0.01 to 0.5 mass %.

The inventors speculate that when polyurethane is produced using a non-tin catalyst, organic acids contained as impurities in the non-tin catalyst are replaced by polyurethane adsorbed to the filler (e.g., silica particles), causing the filler to settle. Therefore, the inventors believe that by including an inorganic viscosity modifier in the aqueous urethane resin composition, the settling of the filler is suppressed by the sol-forming action of the inorganic viscosity modifier. In addition, the inorganic viscosity modifier becomes a weak base in water, which is believed to suppress the decrease in pH of the surface treatment agent liquid and contribute to suppressing the settling of the filler.

<Crosslinking Agent (E)>
In order that the aqueous urethane resin composition of the present invention may be effectively used as a surface treatment agent, the aqueous urethane resin composition contains a crosslinking agent (E) in order to improve the mechanical strength of the coating film.
Examples of the crosslinking agent (E) that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, carbodiimide-based crosslinking agents, oxazolidine-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, etc. These crosslinking agents may be used alone or in combination of two or more kinds.
Among these, from the viewpoints of safety to the human body and the environment, and a balance between reactivity and pot life, the crosslinking agent (E) is preferably a carbodiimide-based crosslinking agent.

The amount of crosslinking agent (E) used is preferably in the range of 0.3 to 9 mass % as an active ingredient in the aqueous urethane resin composition, and more preferably in the range of 0.5 to 5 mass %.

<Other ingredients>
The aqueous urethane resin composition of the present invention may contain other components (additives) as necessary in addition to the above-mentioned urethane resin (A), water (B), filler (C), and inorganic viscosity modifier (D), or the above-mentioned urethane resin (A), water (B), filler (C), inorganic viscosity modifier (D), and crosslinking agent (E).

Examples of other components that can be used include pH adjusters, dispersants, silicone additives, thickeners (viscosity adjusters), emulsifiers, defoamers, leveling agents, viscoelasticity adjusters, defoamers, wetting agents, 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 other components may be used alone or in combination of two or more.

The aqueous urethane resin composition of the present invention may contain a base such as an amine as a pH adjuster. The combined use of the pH adjuster is believed to be effective in suppressing the settling of the filler.
The aqueous urethane resin composition of the present invention may also contain an anionic, nonionic or salt type dispersant, which is also believed to be effective in preventing the settling of the filler.

The aqueous urethane resin composition of the present invention may contain a silicone additive (silicone compound). The silicone additive is not particularly limited and can be appropriately selected depending on the purpose, but examples of the silicone additive that can be used include polydimethylsiloxane, polymethylphenylsiloxane, polymethylhydrogensiloxane, polymethylphenylhydrogensiloxane; modified products thereof; and copolymers of these silicone compounds with acrylic. These silicone compounds may be used alone or in combination of two or more kinds. Of these, it is preferable to use polydimethylsiloxane because it provides even better abrasion resistance.

The silicone additive is preferably in the form of an emulsion dispersed in water (B) in view of its affinity with water (B). In such a case, a known surfactant may also be included.

The content (solids content) of the silicone additive is preferably in the range of 0.01 to 10 mass %, more preferably in the range of 0.1 to 7 mass %, and even more preferably in the range of 0.5 to 5 mass %, in order to obtain even better abrasion resistance.

The aqueous urethane resin composition of the present invention may contain a viscosity modifier (thickener) other than the inorganic viscosity modifier (D). Examples of viscosity modifiers (thickeners) that can be used include cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, and carboxymethyl cellulose, polyacrylates, polyvinylpyrrolidone, urethanes, polyethers, and the like. Among these, urethane-based associative thickeners are preferred because they exhibit good compatibility with the urethane resin (A).

The aqueous urethane resin composition of the present invention may be a one-part type in which all components are mixed in advance, or a two-part type in which a base composition and a hardener composition are separated and mixed before use.

(Characteristics of the Water-Based Urethane Resin Composition)
The aqueous urethane resin composition of the present invention containing the above-mentioned components can exhibit various properties required of a surface treatment agent, such as excellent abrasion resistance to the surface of an article, not impairing the flexibility of the article, and excellent matte feel (glossiness), and can be effectively used as a surface treatment agent.
Furthermore, even if the aqueous urethane resin composition of the present invention contains a polyurethane produced using a non-tin catalyst, it is an aqueous urethane resin composition that does not cause filler settling and has excellent storage stability.

(Surface treatment agent)
The surface treatment agent of the present invention contains the above-mentioned aqueous urethane resin composition of the present invention.
The aqueous urethane resin composition of the present invention can provide a coating film having excellent chemical resistance, and therefore can be suitably used as a surface treatment agent (paint) to be applied to various articles such as synthetic leather, polyvinyl chloride (PVC) leather, thermoplastic olefin resin (TPO) leather, dashboards, instrument panels, etc.

The article of the present invention has a layer formed from a surface treatment agent.

Specific examples of articles include synthetic leather, artificial leather, natural leather, polyvinyl chloride (PVC) leather used in automobile interior seats, sports shoes, clothing, furniture, thermoplastic olefin (TPO) leather, dashboards, instrument panels, etc.

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 be explained in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. In the examples, the terms "parts", "%", etc. are based on mass unless otherwise specified.

(Production Example 1)
Into a four-neck flask, 558 parts of methyl ethyl ketone, 964 parts of polycarbonate diol (based on 1,6-hexanediol, number average molecular weight 2000), 43 parts of dimethylolpropionic acid, 295 parts of dicyclohexylmethane diisocyanate, and 0.05 parts of bismuth carboxylate were sequentially charged and reacted at 70° C. for 4 hours. The mixture was cooled to 40° C., and 33 parts of triethylamine were charged. With continued stirring, 2,516 parts of water were charged in portions over 1 hour, and then 19 parts of ethylenediamine were charged and reacted at 40° C. for another 1 hour. Methyl ethyl ketone was distilled off under reduced pressure to obtain a polyurethane-containing liquid containing polyurethane (A) with a non-volatile content of 35%.

(Production Example 2)
970 parts of water was added to a stainless steel mug, and 30 parts of inorganic viscosity modifier powder mainly composed of synthetic hectorite was added in portions over 30 minutes while stirring with a small disperser. Stirring was continued for 30 minutes to obtain a diluted solution of inorganic viscosity modifier (D).

Example 1
A polyurethane-containing liquid containing 350 parts of polyurethane (A), 550 parts of water (B), 20 parts of a dry silica-based matting agent (C), a diluted solution of 20 parts of an inorganic viscosity modifier (D), 30 parts of a polymer-based dispersant (40% active ingredient), and 30 parts of a polydimethylsiloxane water dispersion (65% active ingredient) were stirred for 30 minutes using a small disperser to obtain an aqueous urethane resin composition (1-1).
3 parts of a carbodiimide-based crosslinking agent (E) (40% active ingredient) was added to 100 parts of the aqueous urethane resin composition (1-1) and stirred for 2 minutes with a small disperser to obtain an aqueous urethane resin composition (1-2). The aqueous urethane resin composition (1-1) was used as an aqueous surface treatment agent (1), and the aqueous urethane resin composition (1-2) was used as a coating material (1).

The aqueous urethane resin composition obtained in Example 1, and the aqueous surface treatment agent and paint made of the aqueous urethane resin composition were used to carry out the following evaluations. The results are shown in Table 1 below.

<Evaluation of storage stability>
The aqueous urethane resin composition (1-1) was filled into a 1-liter plastic bottle to about 90% and allowed to stand at room temperature for 4 weeks, after which the bottom of the bottle was scooped with a spatula to observe whether or not sedimentation had occurred.

<Evaluation of Matte Feeling>
The aqueous urethane resin composition (1-2) was applied onto a piece of urethane synthetic leather cut into A4 size pieces, dried, and left to stand for 3 days to prepare a sample for evaluation. The gloss value was measured at a measurement angle of 60° using a gloss meter Micro Trigloss (manufactured by BYK).
Coating conditions: Bar coater with wet film thickness of 50 μm Drying conditions: 2 minutes in a gear oven set at 120° C.

<Evaluation of Abrasion Resistance>
A test piece of about 7 cm wide and about 30 cm long was cut out from the evaluation sample and tested using a flat surface abrasion tester (manufactured by Intec). A stainless steel wire with a diameter of 4.5 mm, a cushioning material with a thickness of 10 mm (compressive stress 1 N/cm2), and the test piece were placed on a table in that order, and the test piece was fixed so that it would not loosen. A weight of 2 kg including the head was placed on the friction head equipped with No. 6 canvas, and friction was performed with an amplitude of 140 mm at 60 reciprocations per minute. The abrasion resistance was evaluated by the number of reciprocations until the urethane resin layer of the synthetic leather was broken and the fabric was exposed.

<Evaluation of Flexibility>
A test piece measuring 2.5 cm wide and 12 cm long was cut out from the evaluation sample and tested using a Scott kneading tester (manufactured by Intec). The urethane resin layer of the synthetic leather was placed on the outside, and the condition after 2,000 reciprocating strokes under a 1 kg load was compared to evaluate the flexibility.

(Comparative Example 1)
A polyurethane-containing liquid containing 350 parts of polyurethane (A), 570 parts of water (B), 20 parts of a dry silica-based matting agent (C), 30 parts of a polymer-based dispersant (40% active ingredient), and 30 parts of a polydimethylsiloxane water dispersion (65% active ingredient) were treated in the same manner as in Example 1 to obtain an aqueous urethane resin composition (2-1).
An aqueous urethane resin composition (2-2) was obtained in the same manner as in Example 1, except that 100 parts of the aqueous urethane resin composition (2-1) was used instead of 100 parts of the aqueous urethane resin composition (1-1). The aqueous urethane resin composition (2-1) was used as an aqueous surface treatment agent (2), and the aqueous urethane resin composition (2-2) was used as a coating material (2).
The aqueous urethane resin composition, and the aqueous surface treatment agent and paint of Comparative Example 1 were also evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

(Production Example 2)
A polyurethane-containing liquid containing polyurethane (G) and a nonvolatile content of 35% was obtained in the same manner as in Production Example 1, except that 0.05 parts of dibutyltin dilaurate were used instead of 0.05 parts of bismuth carboxylate.

(Comparative Example 2)
An aqueous urethane resin composition (3-1) was obtained in the same manner as in Comparative Example 1, except that a polyurethane-containing liquid containing 350 parts of polyurethane (G) was used instead of the polyurethane-containing liquid containing 350 parts of polyurethane (A).
An aqueous urethane resin composition (3-2) was obtained in the same manner as in Example 1, except that 100 parts of the aqueous urethane resin composition (3-1) was used instead of 100 parts of the aqueous urethane resin composition (1-1). The aqueous urethane resin composition (3-1) was used as an aqueous surface treatment agent (3), and the aqueous urethane resin composition (3-2) was used as a coating material (3).
The aqueous urethane resin composition, and the aqueous surface treatment agent and paint of Comparative Example 2 were also evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

[0113] From the above examples, it was confirmed that the aqueous urethane resin composition of the present invention containing the inorganic viscosity modifier (D) is an aqueous urethane resin composition that can impart excellent abrasion resistance to the surface of an article, does not impair the flexibility of the article, and can be suitably used as a surface treatment agent that has an excellent matte feel (glossiness), does not contain tin, prevents the settling of the filler, and has excellent storage stability.

Claims (8)

An aqueous urethane resin composition comprising a urethane resin (A) formed using a non-tin catalyst, water (B), a filler (C), an inorganic viscosity modifier (D), and a silicone additive,
The filler (C) is silica,
The inorganic viscosity modifier (D) is selected from the group consisting of montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, and bentonite ;
The content of the inorganic viscosity modifier (D) in the aqueous urethane resin composition is in the range of 0.01 to 0.5 mass% . The aqueous urethane resin composition according to claim 1, wherein the amount of the filler (C) used is in the range of 0.1 to 10 mass% in the aqueous urethane resin composition. The aqueous urethane resin composition according to claim 1 or 2, wherein the non-tin catalyst is bismuth carboxylate. The aqueous urethane resin composition according to any one of claims 1 to 3 , further comprising a crosslinking agent (E). The aqueous urethane resin composition according to claim 4 , wherein the crosslinking agent (E) is a carbodiimide-based crosslinking agent. The aqueous urethane resin composition according to any one of claims 1 to 5, wherein the content (solid content) of the silicone additive is in the range of 0.01 to 10 mass%. A surface treatment agent containing the aqueous urethane resin composition according to any one of claims 1 to 6. An article having a layer formed by the surface treatment agent according to claim 7.