JP7512789B2 - Water-based polyurethane resin dispersion - Google Patents

Description

The present invention relates to an aqueous polyurethane resin dispersion that can form a coating film with excellent alcohol resistance.

Polyurethane resins are widely used as paints, adhesives, textile processing agents, paper processing agents, inks, coating agents, etc. Compared to conventional solvent-based polyurethanes, they can reduce volatile organic compounds, so they are increasingly being replaced by solvent-based polyurethanes as an environmentally friendly material.

The above-mentioned solvent-based urethane has good film-forming properties regardless of the heating temperature because the urethane resin is dissolved in a solvent, whereas water-based polyurethane resin dispersions have a particulate shape and form films by fusion of the particles, resulting in inferior film-forming properties compared to solvent-based urethanes, which causes the problem of reduced chemical resistance, especially alcohol resistance, of the resulting coating film.

In order to improve the above performance, various types of aqueous polyurethane resin dispersions have been developed. For example, Patent Document 1 reports that the chemical resistance of the resulting coating film is improved by using a polycarbonate polyol having an alicyclic structure as the raw polyol of the polyurethane resin.

In addition, as disclosed in Patent Document 2, for example, it is known that a film obtained from an aqueous dispersion of a composite resin of a polyurethane resin having a structure derived from an aliphatic polycarbonate polyol and a structure derived from a hydroxyl group-containing polyamine, and an acrylic resin, exhibits excellent chemical resistance.
In addition, as disclosed in Patent Document 3, for example, it is known that a coating film obtained from a polyurethane resin dispersion composition having a structure derived from an aliphatic polycarbonate polyol and a structure derived from a hydroxyl group-containing polyamine, and characterized in that the molar ratio of isocyanate groups (NCO) to hydroxyl groups (OH) in the aqueous resin dispersion composition (NCO/OH ratio) is 0.1 to 10, exhibits excellent chemical resistance.

Japanese Patent Application Laid-Open No. 6-248046 JP 2019-172753 A JP 2020-083902 A

Patent Document 1 discloses acid resistance and alkali resistance, but does not disclose alcohol resistance, so the effect on alcohol resistance is unclear. In addition, Patent Document 2 has a problem that the burden on the manufacturing process is large because the urethane resin synthesis process and the acrylic monomer polymerization process are essential for the production of the composite resin aqueous dispersion. Urethane generally tends to be corroded by alcohol, and urethane as a coating agent is not compatible with alcohol used for sterilization, for example. Therefore, there is a demand for the aqueous dispersion of polyurethane resin itself to have alcohol resistance.
In Patent Document 3, as described in the Reference Examples of this specification, the chemical resistance is evaluated based on the change in the appearance of the coating film when it comes into contact with a chemical solution, but this is insufficient as a method for evaluating alcohol resistance. In particular, the chemical resistance when wiping with an alcoholic chemical, which has become increasingly demanded in recent years, could not be evaluated by the method of contacting the chemical solution. In addition, the relationship between the components of the aqueous polyurethane resin dispersion and the alcohol resistance was not clear.

The object of the present invention is to provide an aqueous polyurethane resin dispersion that can solve the problems of the above-mentioned conventional techniques and form a coating film with excellent alcohol resistance.

The present inventors conducted various studies to overcome the problems of the conventional techniques described above, and as a result, discovered that a coating film formed from an aqueous polyurethane resin dispersion obtained by dispersing polyurethane resin (A) having a structure derived from polycarbonate polyol (Aa) having an alicyclic structure, a structure derived from polyisocyanate (Ab), a structure derived from acidic group-containing polyol (Ac) and a structure derived from hydroxyl group-containing polyamine (Ad) in an aqueous medium, in which the polyurethane resin (A) has a hydroxyl value of 3.0 to 15 mgKOH/g, has good alcohol resistance, leading to the present invention.

Specifically, the present invention is as follows.
(1) A first invention is an aqueous polyurethane resin dispersion, in which polyurethane resin (A) having a structure derived from a polycarbonate polyol (Aa) having an alicyclic structure, a structure derived from a polyisocyanate (Ab), a structure derived from an acidic group-containing polyol (Ac), and a structure derived from a hydroxyl group-containing polyamine (Ad) is dispersed in an aqueous medium, and the hydroxyl value of the polyurethane resin (A) is in the range of 3.0 to 15 mgKOH/g.
(2) A second invention is the aqueous polyurethane resin dispersion according to the above (1), which further has a structure derived from a chain extender (Ae).
(3) A third invention is the aqueous polyurethane resin dispersion according to the above (1) or (2), wherein the content of the alicyclic structure in the polycarbonate polyol (Aa) having an alicyclic structure is 1 to 50 mass% based on the total amount of the polycarbonate polyol (Aa).
(4) A fourth invention is the aqueous polyurethane resin dispersion according to any one of (1) to (3) above, wherein the polycarbonate polyol (Aa) having an alicyclic structure contains a cyclohexane ring.
(5) A fifth invention is the aqueous polyurethane resin dispersion according to any one of (1) to (4), wherein the polyisocyanate (Ab) is at least one selected from the group consisting of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.
(6) A sixth aspect of the present invention is the aqueous polyurethane resin dispersion according to any one of (1) to (5), wherein the hydroxyl-containing polyamine (Ad) is at least one selected from the group consisting of 3,5-diaminobenzyl alcohol, 1,3-diamino-2-propanol, 2,2'-(ethylene bisimino) bisethanol, N-(2-hydroxyethyl)-N'-(2-aminoethyl)ethylenediamine, N-(3-hydroxypropyl)ethylenediamine, 2-[bis(2-aminoethyl)amino]ethanol, 1-[2-[(2-aminoethyl)amino]ethyl]amino-2-propanol, N,N-bis(hydroxyethyl)diethylenetriamine, N1,N4-bis(hydroxyethyl)diethylenetriamine, N1-(2-hydroxypropyl)triethylenetetraamine, N4-(2-hydroxypropyl)triethylenetetraamine, N-(2-hydroxypropyl)triethylenetetraamine, and 2-(2-aminoethylamino)ethanol.
(7) A seventh aspect of the present invention is the aqueous polyurethane resin dispersion according to any one of (1) to (6) above, wherein the hydroxyl group-containing polyamine (Ad) is 2-(2-aminoethylamino)ethanol.
(8) An eighth invention is the aqueous polyurethane resin dispersion according to any one of (1) to (7), wherein the content of the alicyclic structure contained in the polyurethane resin (A) is 30 to 50 mass% on a solids content basis with respect to the total amount of the polyurethane resin (A).
(9) A ninth invention is a coating composition containing the aqueous polyurethane resin dispersion according to any one of (1) to (8) above.
(10) A tenth invention is a coating agent composition containing the aqueous polyurethane resin dispersion according to any one of (1) to (8) above.
(11) An eleventh aspect of the present invention is a coating film obtained by drying the aqueous polyurethane resin dispersion according to any one of (1) to (8) above.
(12) A twelfth aspect of the present invention is a method for producing a coating film, comprising a step of subjecting the aqueous polyurethane resin dispersion according to any one of (1) to (8) above to a temperature of 20 to 100° C.

The present invention provides an aqueous polyurethane resin dispersion that can form a coating film with excellent alcohol resistance.

The aqueous polyurethane resin dispersion of the present invention is an aqueous polyurethane resin dispersion obtained by dispersing in an aqueous medium a polyurethane resin (A) having a structure derived from a polycarbonate polyol (Aa) having an alicyclic structure, a structure derived from a polyisocyanate (Ab), a structure derived from an acidic group-containing polyol (Ac), and a structure derived from a hydroxyl group-containing polyamine (Ad), and the hydroxyl value of the polyurethane resin (A) is 3.0 to 15 mgKOH/g.

<Polyurethane resin (A)>
The polyurethane resin (A) used in the present invention (hereinafter, sometimes referred to as "(A)") has a structure derived from a polycarbonate polyol (Aa) having an alicyclic structure, a structure derived from a polyisocyanate (Ab), a structure derived from an acidic group-containing polyol (Ac), and a structure derived from a hydroxyl group-containing polyamine (Ad), and is dispersed in an aqueous medium. This polyurethane resin (A) has a hydroxyl value of 3.0 to 15 mgKOH/g. The polyurethane resin (A) or the components from which each of its structural units is derived may be known, and the manufacturing method thereof is not limited. In addition to the above, the polyurethane resin (A) may have a structural unit derived from a chain extender (Ae), a polyol (Af) other than (Aa) and (Ac), or a neutralizer (Ag).

(Polycarbonate polyol (Aa) having an alicyclic structure)
The polyurethane resin (A) has a structural unit derived from a polycarbonate polyol (Aa) having an alicyclic structure. The polycarbonate polyol (Aa) having an alicyclic structure is obtained by reacting a polyol monomer containing at least one polyol component having an alicyclic structure with a carbonate ester or phosgene. From the viewpoints of safety and handling of reagents, etc., it is easy to manufacture, and there is no by-production of terminal chlorinated products, so a polycarbonate polyol obtained by reacting a polyol monomer containing at least one polyol component having an alicyclic structure with a carbonate ester is preferred.

At least a part of the polyol monomer constituting the polycarbonate polyol (Aa) having an alicyclic structure has an alicyclic structure. The content of the alicyclic structure is preferably 1 to 55 mass% based on the total amount of the polycarbonate polyol (Aa), more preferably 1 to 50 mass%, even more preferably 5 to 45 mass%, and even more preferably 10 to 40 mass%. When the content of the alicyclic structure is within the above range, it is preferable in that a coating film excellent in hardness and adhesion is provided and alcohol resistance is improved.
The content of the alicyclic structure refers to the content of the cyclohexane residue when the structure contains a cyclohexane ring, and also refers to the content ratio of the cyclohexane residue in the case of dicyclohexylmethane. When a substituent is bonded to the cyclohexane ring, the cyclohexane residue refers to the structure of the cyclohexane ring excluding the substituent.

As the polyol monomer having an alicyclic structure constituting the polycarbonate polyol (Aa) having an alicyclic structure, known ones can be used. Among them, it is preferable to use a polyol monomer containing a cyclohexane ring as the alicyclic structure from the viewpoint of hardness and alcohol resistance when formed into a coating film. Specific examples of polyol monomers having an alicyclic structure include 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 2,5-bis(hydroxymethyl)-1,4-dioxane, 2,7-norbornanediol, tetrahydrofuran dimethanol, 1,4-bis(hydroxyethoxy)cyclohexane, etc.

As the polyol monomer having an alicyclic structure constituting the polycarbonate polyol (Aa) having an alicyclic structure, 1,4-cyclohexanedimethanol can be preferably used from the viewpoint of improving alcohol resistance.

The polycarbonate polyol (Aa) having an alicyclic structure may contain, as a constituent, a polyol that does not have an alicyclic structure, in addition to the polyol monomer having an alicyclic structure. The polyol that does not have an alicyclic structure is not particularly limited, and may be, for example, aliphatic polyols such as linear aliphatic diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,9-nonanediol, branched aliphatic diols such as 2-methyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol, trifunctional or higher polyhydric alcohols such as trimethylolpropane and pentaerythritol; 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzene Examples of the polyol include aromatic diols such as dimethanol, 4,4'-naphthalenedimethanol, and 3,4'-naphthalenedimethanol; polyester polyols of hydroxycarboxylic acids and diols such as polyester polyols of 6-hydroxycaproic acid and hexanediol; polyester polyols of dicarboxylic acids and diols such as polyester polyols of adipic acid and hexanediol; and polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Aliphatic polyols are preferred, linear aliphatic diols are more preferred, and 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are even more preferred.

The polyol monomers of the polycarbonate polyol (Aa) having an alicyclic structure may be used alone or in combination of two or more kinds. However, at least one type of polyol having an alicyclic structure is included.

The carbonate ester is not particularly limited, but examples thereof include aliphatic carbonate esters such as dimethyl carbonate and diethyl carbonate; aromatic carbonate esters such as diphenyl carbonate; and cyclic carbonate esters such as ethylene carbonate. In addition, phosgene and the like capable of producing polycarbonate polyol can also be used. Among these, aliphatic carbonate esters are preferred, and dimethyl carbonate is more preferred, because of the ease of producing polycarbonate polyol (Aa) having an alicyclic structure.

The polycarbonate polyol (Aa) having an alicyclic structure may contain ether bonds or ester bonds in its molecule in a number less than the average number of carbonate bonds in one molecule, as long as the properties of the polycarbonate polyol are not impaired.

The polycarbonate polyol (Aa) having an alicyclic structure preferably has a number average molecular weight (Mn) of 400 to 5,000. When Mn is 400 or more, the performance as a soft segment is good, and cracks are unlikely to occur when a coating film is formed. When Mn is 5,000 or less, the reactivity of the polycarbonate polyol (Aa) having an alicyclic structure with the polyisocyanate (Ab) is not reduced, and problems such as the production process of the urethane prepolymer taking a long time, the reaction not proceeding sufficiently, and the viscosity of the polycarbonate polyol becoming high and difficult to handle do not occur. The Mn of the polycarbonate polyol (Aa) having an alicyclic structure is more preferably 500 to 3,500, and even more preferably 600 to 2,500. In the present invention, Mn is a value calculated from the hydroxyl value and the quantitative value of the composition by ¹ H-NMR or gas chromatography after alkali hydrolysis.

A method for producing a polycarbonate polyol (Aa) having an alicyclic structure from a polyol monomer and a carbonate ester includes, for example, adding a carbonate ester and an excess number of moles of polyol relative to the number of moles of the carbonate ester to a reactor, reacting for 5 to 6 hours at a temperature of 160 to 200°C and a pressure of about 50 mmHg, and then reacting for several hours at 200 to 220°C and a pressure of a few mmHg or less. In the above reaction, it is preferable to carry out the reaction while removing the by-product alcohol from the system. In that case, if the carbonate ester escapes from the system by forming an azeotrope with the by-product alcohol, an excess amount of carbonate ester may be added. In the above reaction, a catalyst such as titanium tetrabutoxide may be used.

(Polyisocyanate (Ab))
The polyurethane resin (A) has a structural unit derived from a polyisocyanate (Ab). As the polyisocyanate (Ab), a known one can be used. For example, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl- ... aromatic isocyanate compounds such as naphthylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4',4''-triphenylmethane triisocyanate, m-isocyanatophenylsulfonyl isocyanate, and p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), Aliphatic isocyanate compounds such as dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate; isophorone diisocyanate Examples of the isocyanate include alicyclic isocyanate compounds such as isocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4-dicyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, and 2,6-norbornane diisocyanate. The polyisocyanate (Ab) may have a structure that is partially or entirely derivatized by isocyanuration, carbodiimidization, biuretization, or the like.

Among the polyisocyanates (Ab), aromatic isocyanate compounds and alicyclic isocyanate compounds are preferred from the viewpoint of controlling reactivity, and isophorone diisocyanate (IPDI), 4,4'-diphenylmethane diisocyanate (MDI) and 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) are more preferred from the viewpoint of improving alcohol resistance. The polyisocyanates (Ab) may be used alone or in combination of two or more kinds.

It is preferable that the polyisocyanate (Ab) is at least one selected from the group consisting of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

The amount of isocyanate compound (Ab) used is preferably an amount such that the ratio of the isocyanate groups of polyisocyanate (Ab) to the hydroxyl groups derived from all polyols (isocyanate groups/hydroxyl groups (molar ratio)) is in the range of 0.5 to 3.0, and more preferably in the range of 1.2 to 2.0. The total polyols refers to the total of polycarbonate polyol (Aa) having an alicyclic structure, acidic group-containing polyol (Ac) described below, and other polyols (Af) described below, and does not include components derived from hydroxyl group-containing polyamine (Ad) described below.

(Acidic Group-Containing Polyol (Ac))
The polyurethane resin (A) preferably has a structural unit derived from an acidic group-containing polyol (Ac) in order to improve dispersibility in water. The acidic group-containing polyol (Ac) is a polyol containing two or more hydroxyl groups and one or more acidic groups in one molecule. The acidic group-containing polyol (Ac) may be used alone or in combination of two or more kinds.

As the acidic group-containing polyol (Ac), known polyols can be used. Examples include dimethylolalkanoic acids such as 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid; N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, and 3,6-dihydroxy-2-toluenesulfonic acid. Among these, from the viewpoint of ease of availability, dimethylolalkanoic acids having 4 to 12 carbon atoms and containing two methylol groups are preferred, and among dimethylolalkanoic acids, 2,2-dimethylolpropionic acid is more preferred.

(Hydroxyl-containing polyamine (Ad))
The polyurethane resin (A) has a structural unit derived from a hydroxyl group-containing polyamine (Ad). By introducing the hydroxyl group-containing polyamine (Ad) into the polyurethane resin (A), the molecular weight is increased and further hydroxyl groups are imparted.

The hydroxyl-containing polyamine (Ad) contains one or more hydroxyl groups (excluding phenolic hydroxyl groups) and two or more amino groups and/or imino groups in one molecule, and any known compound can be used. As such compounds, alkanol polyamines other than tertiary amines are preferred, and specific examples include aromatic alkanol diamines such as 3,5-diaminobenzyl alcohol, 1,3-diamino-2-propanol, 2,2'-(ethylene bisimino) bisethanol, N-(2-hydroxyethyl)-N'-(2-aminoethyl) ethylenediamine, N-(3-hydroxypropyl) ethylenediamine, 2-[bis(2-aminoethyl) amino] ethanol, 1-[2-[(2-aminoethyl) amino] ethyl] amino-2-propanol, N,N-bis(hydroxyethyl) diethylenetriamine, N1,N4-bis(hydroxyethyl) diethylenetriamine, N1-(2-hydroxypropyl) triethylenetetraamine, N4-(2-hydroxypropyl) triethylenetetraamine, N-(2-hydroxypropyl) triethylenetetraamine, and aliphatic alkanol polyamines such as 2-(2-aminoethylamino) ethanol.

As the hydroxyl group-containing polyamine (Ad), 2-(2-aminoethylamino)ethanol can be preferably used from the viewpoints of ease of synthesis of the polyurethane resin (A), ease of imparting hydroxyl groups to the polyurethane resin (A), and improvement of the alcohol resistance of the coating film of the present invention.

The hydroxyl-containing polyamine (Ad) may be used alone or in combination with multiple types.

(Chain extender (Ae))
The polyurethane resin (A) may have a structural unit derived from a chain extender (Ae) in order to increase the molecular weight. The chain extender (Ae) is a compound other than the polycarbonate polyol (Aa) having an alicyclic structure, the acidic group-containing polyol (Ac), the hydroxyl group-containing polyamine (Ad), and the other polyol (Af) described later, and is a compound reactive with the isocyanato group of the polyurethane prepolymer.

As the chain extender (Ae), known ones can be used. For example, amine compounds such as ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis(aminomethyl)cyclohexane, xylylenediamine, piperazine, 2,5-dimethylpiperazine, diethylenetriamine, and triethylenetetramine, and water can be mentioned, with amine compounds being preferred.

Among the chain extenders (Ae), polyamines with a number average molecular weight (Mn) of 300 or less are preferred. Having an Mn of 300 or less is necessary to increase the cohesive strength of the polyurethane resin, and using polyamines with two or more functional groups in one molecule is necessary to increase the Mn of the polyurethane resin and improve its durability.

The chain extender (Ae) may be used alone or in combination with multiple types.

(Amounts of Hydroxyl-Containing Polyamine (Ad) and Chain Extender (Ae) Used)
The total amount of the hydroxyl-containing polyamine (Ad) and the chain extender (Ae) used is preferably equal to or less than the equivalent of the isocyanato group that serves as the chain extension starting point in the polyurethane prepolymer, which is a synthetic intermediate of the polyurethane resin (A), and more preferably 0.7 to 0.99 equivalents of the isocyanato group in the polyurethane prepolymer. By adding the hydroxyl-containing polyamine (Ad) and the chain extender (Ae) in an amount equal to or less than the equivalent of the isocyanato group in the polyurethane prepolymer, there is a tendency that the strength of the coating film can be increased without decreasing the molecular weight of the chain-extended polyurethane resin (A).
The hydroxyl group-containing polyamine (Ad) is used so that the hydroxyl group value of the polyurethane resin (A) is in the range of 3.0 to 15 mgKOH/g. The specific amount of the hydroxyl group-containing polyamine (Ad) used is preferably 0.1 to 10 mass %, more preferably 0.3 to 7.0 mass %, and even more preferably 0.5 to 5.0 mass %, based on the total solid content of the polycarbonate polyol (Aa) having an alicyclic structure, the polyisocyanate (Ab), and the acidic group-containing polyol (Ac).
When the chain extender (Ae) is used, the amount of the chain extender (Ae) used is preferably 0.1 to 15 mass %, more preferably 0.1 to 10 mass %, based on the total solid contents of the polycarbonate polyol (Aa) having an alicyclic structure, the polyisocyanate (Ab), and the acidic group-containing polyol (Ac).

(Polyol (Af) other than (Aa) and (Ac))
The polyurethane resin (A) may have a structural unit derived from a polyol (Af) other than the polycarbonate polyol (Aa) having an alicyclic structure and the acidic group-containing polyol (Ac).
Other polyols (Af) that can be used include known polyols, such as polyether polyols, such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, random copolymers or block copolymers of ethylene oxide and propylene oxide, or ethylene oxide and butylene oxide; short-chain aliphatic polyols, such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 3-methyl-1,5-pentanediol, and 2-butyl-2-ethyl-1,3-propanediol. Diols; alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A; aromatic diols such as 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol, 4,4'-naphthalenedimethanol, and 3,4'-naphthalenedimethanol; trifunctional or higher polyhydric alcohols such as trimethylolpropane and pentaerythritol; diols such as bisphenol A, hydroquinone, bishydroxyethoxybenzene, and alkylene oxide adducts thereof; terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'- Examples of the polyester polyols include polyester polyols obtained from polycarboxylic acids such as diphenyl ether dicarboxylic acid, trimellitic acid, pyromellitic acid, adipic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecanedicarboxylic acid, dimer acid, and hydrogenated dimer acid, and the above-mentioned polyols.
The other polyol compound (Af) is preferably contained in an amount of less than 70 mass% based on the total amount of the polyol compounds (Aa), (Ac) and (Af), more preferably contained in an amount of less than 60 mass%, even more preferably contained in an amount of less than 50 mass%, and even more preferably contained in an amount of less than 40 mass%. Depending on the physical properties required for the aqueous polyurethane resin, the type and amount of the other polyol compound (Af) can be appropriately adjusted by a person skilled in the art within a range that does not impair the effects of the present invention, but the structure derived from the other polyol compound (Af) does not need to be contained in the polyurethane resin (A).

(Neutralizing Agent (Ag))
The polyurethane resin (A) may have a constituent unit derived from a neutralizing agent (Ag) in order to neutralize the acidic group. The neutralizing agent (Ag) may be used alone or in combination of two or more kinds.

As the neutralizing agent (Ag), known neutralizing agents can be used. For example, organic amines such as trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-phenyldiethanolamine, 2-dimethylaminoethanol, 2-(dimethylamino)-2-methyl-1-propanol, diethylethanolamine, N-methylmorpholine, and pyridine; inorganic alkalis such as sodium hydroxide and potassium hydroxide, and ammonia can be used.

The neutralizing agent (Ag) preferably has a boiling point of 200°C or less, more preferably in the range of -50 to 180°C, since it volatilizes and disappears from the polyurethane film at the temperature (usually 50 to 180°C) when the aqueous medium in the aqueous polyurethane resin dispersion composition is dried, resulting in even better adhesive strength. When obtaining a dry coating film in a short time of several seconds to 1 hour at a low temperature of 100°C or less, the boiling point is preferably 130°C or less, more preferably 110°C or less.

When using a neutralizing agent (Ag), the amount used is preferably in the range of 0.8 to 1.2 times the number of moles of the acidic groups contained in the polyurethane resin (A). When the amount of the neutralizing agent (Ae) used is 0.8 times or more the number of moles of the acidic groups contained in the aqueous polyurethane resin dispersion, the stability of the resulting dispersion is high, and when it is 1.2 times or less, a coating film with high adhesion to the substrate can be obtained in a short time of several seconds to 1 hour under low-temperature drying at 100°C or less.

In the polyurethane resin (A), the total hydroxyl equivalent number of the polycarbonate polyol (Aa) having an alicyclic structure, the acidic group-containing polyol (Ac), and the other polyol (Af) is preferably 50 to 4000. If the hydroxyl equivalent number is within this range, it is easy to manufacture an aqueous polyurethane resin dispersion containing the obtained polyurethane resin. From the viewpoint of the storage stability of the obtained aqueous polyurethane resin dispersion, the hydroxyl equivalent number is preferably 100 to 3500, more preferably 120 to 3000, and even more preferably 130 to 2500. The total amount of the acidic group-containing polyol (Ac) and the other polyol (Af) used can be any amount within the range that can achieve the above range, but it is preferable that it is contained in an amount of less than 80 mass% based on the total amount of the polyol compounds (Aa), (Ac), and (Af).

The hydroxyl group equivalent number can be calculated by the following formulas (1) and (2).
Hydroxyl equivalent number of each polyol component=molecular weight of each polyol component/number of hydroxyl groups of each polyol component (1)
Total hydroxyl equivalent number of polyol components=M/total mole number of polyol components (2)
In formula (2), M represents [[hydroxyl equivalent number of polycarbonate polyol component × number of moles of polycarbonate polyol component] + [hydroxyl equivalent number of acidic group-containing polyol × number of moles of acidic group-containing polyol] + [hydroxyl equivalent number of other polyol × number of moles of other polyol]].

(Method for producing aqueous polyurethane resin dispersion)
Next, a method for producing the aqueous polyurethane resin dispersion will be described. The aqueous polyurethane resin dispersion is a dispersion of the polyurethane resin (A) in an aqueous medium. The method for producing the aqueous polyurethane resin dispersion includes the following steps.
(I) a step of reacting the polycarbonate polyol (Aa) having an alicyclic structure, the polyisocyanate (Ab), the acidic group-containing polyol (Ac), and optionally a polyol (Af) other than (Aa) and (Ac) to obtain a polyurethane prepolymer;
(II) neutralizing the acidic groups of the polyurethane prepolymer with a neutralizing agent (Ag);
(III) a step of dispersing the polyurethane prepolymer in an aqueous medium, and (IV) a step of reacting the polyurethane prepolymer with a hydroxyl group-containing polyamine (Ad) reactive with an isocyanato group of the polyurethane prepolymer, and a chain extender (Ae).
Furthermore, when an organic solvent is used in step (I), step (V) may include a step of removing the organic solvent.
The aqueous polyurethane resin dispersion of the present invention can be produced by a known method described in known literature (for example, WO 2016/039396, WO 2016/163394, etc.).

(Polyurethane prepolymer)
In the step (I), the polyurethane prepolymer is obtained by reacting a polycarbonate polyol (Aa) having an alicyclic structure, a polyisocyanate (Ab), an acidic group-containing polyol (Ac), and a polyol (Af) other than (Aa) and (Ac). Thus, the polyurethane prepolymer has at least (a1) a structure derived from a polycarbonate polyol having an alicyclic structure, (a2) a structure derived from a polyisocyanate, and (a3) a structure derived from an acidic group-containing polyol, and optionally has (a4) a structure derived from another polyol.

It is preferable that the polyurethane prepolymer has a free isocyanato group content of 0.5 to 5.0% by mass based on the solid content of the polyurethane prepolymer, since this provides good dispersibility in water.

The acid value (AV) of the polyurethane prepolymer is preferably 4 to 40 mgKOH/g, more preferably 6 to 32 mgKOH/g, and even more preferably 8 to 29 mgKOH/g. By making the acid value of the polyurethane prepolymer 4 mgKOH/g or more, there is a tendency that the dispersibility in aqueous media and the storage stability can be improved. Furthermore, by making the acid value of the polyurethane prepolymer 40 mgKOH/g or less, there is a tendency that the water resistance of the polyurethane resin coating film can be increased, and the flexibility of the resulting film can be increased. Furthermore, there is a tendency that the drying property during coating film production can be improved.

The "acid value of the polyurethane prepolymer" refers to the acid value of the so-called solid content, excluding the solvent used in producing the polyurethane prepolymer and the neutralizing agent used to disperse the polyurethane prepolymer in the aqueous medium.

Specifically, the acid value of a polyurethane prepolymer can be calculated using the following formula (3):

[Acid value of polyurethane prepolymer] = [(number of millimoles of acidic group-containing polyol) x (number of acidic groups in one molecule of acidic group-containing polyol) + (number of millimoles of hydroxyalkanoic acid) x (number of acidic groups in one molecule of hydroxyalkanoic acid)] x 56.1 / [total mass of polyisocyanate, acidic group-containing polyol, hydroxyalkanoic acid, blocking agent, polycarbonate polyol with alicyclic structure, and other polyols] ... (3)

(Steps (I) to (V))
The steps (I) to (III) and (V) are carried out by the methods described in the above-mentioned known publications.

The step (IV) of reacting the polyurethane prepolymer with the hydroxyl-containing polyamine (Ad) reactive with the isocyanato group of the polyurethane prepolymer and the chain extender (Ae) is a step of crosslinking the polyurethane prepolymers together and adjusting the molecular weight of the polyurethane resin (A) to a desired range. Furthermore, as described above, the hydroxyl value of the polyurethane resin (A) can be adjusted to a range of 3.0 to 15 mgKOH/g by adjusting the type and amount of the hydroxyl-containing polyamine (Ad).
In the step (IV), a polyol not containing an acidic group and/or a polyol containing an acidic group may be used together with the hydroxyl group-containing polyamine in place of the chain extender (Ae). Examples of such polyols include diol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol, and polyalkylene glycols such as polyethylene glycol.

The step (IV) may be carried out slowly under cooling, or, in some cases, may be carried out by promoting the reaction under heating conditions of 60°C or less. The reaction time under cooling may be, for example, 0.5 to 24 hours, and the reaction time under heating conditions of 60°C or less may be, for example, 0.1 to 6 hours.

In the step (IV), the hydroxyl-containing polyamine is preferably reacted with the polyurethane prepolymer at 60°C or less. Specifically, the polyurethane prepolymer is preferably dispersed in water and then reacted at 60°C or less. If the reaction is carried out at a temperature exceeding 60°C, the hydroxyl groups of the hydroxyl-containing polyamine may react with the isocyanato groups, making it impossible to impart the intended amount of hydroxyl groups.

In the production of the aqueous polyurethane resin dispersion, the steps (II) and (IV) may be carried out in either order, or may be carried out simultaneously. The steps (II) and (III) may be carried out simultaneously. Furthermore, the steps (II), (III) and (IV) may be carried out simultaneously.

(Aqueous Polyurethane Resin Dispersion)
The content of the polyurethane resin (A) in the aqueous dispersion is from 5 to 60% by mass, preferably from 20 to 50% by mass.

The hydroxyl value of the polyurethane resin (A) in the aqueous dispersion is 3.0 to 15 mgKOH/g from the viewpoint of improving the alcohol resistance of the coating film obtained from the aqueous polyurethane resin dispersion, and is preferably 3.5 to 13 mgKOH/g, more preferably 4.0 to 11 mgKOH/g, and even more preferably 5.0 to 10 mgKOH/g from the viewpoint of storage stability. The hydroxyl value is the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 g of sample, and can be measured by Method A of JIS K 1557.

The weight average molecular weight (Mw) of the polyurethane resin (A) in the aqueous dispersion is preferably 200,000 to 10,000,000, more preferably 300,000 to 5,000,000, and even more preferably 400,000 to 2,000,000. The weight average molecular weight is measured by gel permeation chromatography (GPC), and a converted value obtained from a calibration curve of a standard polystyrene prepared in advance can be used. By setting the weight average molecular weight to 200,000 or more, a good coating film tends to be obtained. By setting the weight average molecular weight to 10,000,000 or less, the drying property of the aqueous polyurethane resin dispersion tends to be improved.

The content of the alicyclic structure contained in the polyurethane resin (A) in the aqueous dispersion is preferably 30 to 50 mass% based on the solid content of the total amount of the polyurethane resin (A), more preferably 32 to 48 mass%, and even more preferably 34 to 46 mass%. If the content ratio of the alicyclic structure is within the above range, it is preferable in that it is possible to suppress a decrease in dispersibility of the aqueous polyurethane resin dispersion, an increase in the median diameter of the particles, gelation, hydrolysis, etc. Note that the "content of the alicyclic structure" in the content of the alicyclic structure contained in the polyurethane resin (A) in the aqueous dispersion refers to the content in the polyurethane resin (A) of the alicyclic structure present in all the constituent components of the polyurethane resin (A), such as the polycarbonate polyol (Aa) and the polyisocyanate (Ab).

In the polyurethane resin (A) in the aqueous dispersion, the content of urethane bonds and urea bonds is preferably 7 to 25 mass% based on the solid content, and more preferably 8 to 22 mass%.

The content ratio of urethane bonds and urea bonds can be controlled by the molecular weight of each of the polyisocyanate (Ab), polycarbonate polyol (Aa) having an alicyclic structure, acidic group-containing polyol (Ac), hydroxyl group-containing polyamine (Ad) and other polyols (Af), and optionally the blocking agent and chain extender (Ae), the number of hydroxyl groups, isocyanato groups and amino groups in one molecule, and the usage ratio of each raw material on a solid content basis in the aqueous polyurethane resin dispersion.

By making the content of the urethane bond and urea bond 7% by mass or more, it may be possible to reduce stickiness on the coating film surface after drying. In addition, by making the content of the urethane bond and urea bond 25% by mass or less, it may be possible to improve adhesion between the coating film formed from the aqueous polyurethane resin dispersion and the substrate.

It is clear to those skilled in the art which raw materials each structure/group in polyurethane, such as carbonate and urethane, comes from, and since almost all of the raw materials are incorporated into the polyurethane resin produced, or it is easy to design it that way, the contents of alicyclic structures, urethane bonds, urea bonds, etc. in polyurethane resin (A) can be roughly calculated from the charge amounts, the molecular weights of each raw material, and the molecular weights or mole numbers of the portions corresponding to each structure.

The acid value of the polyurethane resin (A) in the aqueous dispersion is not particularly limited, but is preferably 10 to 40 mgKOH/g, more preferably 15 to 32 mgKOH/g, and even more preferably 17 to 30 mgKOH/g based on the solid content. By setting the acid value of the polyurethane resin (A) in the range of 10 to 40 mgKOH/g based on the solid content, the storage stability tends to be improved. The acid value can be measured in accordance with the indicator titration method of JIS K 1557. In the measurement, the neutralizing agent used to neutralize the acidic groups is removed and the measurement is performed. For example, when organic amines are used as the neutralizing agent, the aqueous polyurethane resin dispersion is applied to a glass plate, and the coating film obtained by drying at a temperature of 60°C and a reduced pressure of 20 mmHg for 24 hours is dissolved in N-methylpyrrolidone (NMP), and the acid value can be measured in accordance with the indicator titration method of JIS K 1557.

The glass transition temperature (Tg) of the polyurethane resin (A) in the aqueous dispersion is preferably -10°C or higher, more preferably -10 to 100°C, even more preferably 10 to 90°C, and even more preferably 30 to 80°C. If the Tg of the polyurethane resin (A) is -10°C or higher, the alcohol resistance is superior.

<Curing Agent (B)>
The curing agent (B) (hereinafter sometimes referred to as "(B)") that can be optionally used in the present invention is a compound that can react with functional groups, preferably hydroxyl groups and acidic groups, in the polyurethane resin (A) and contribute to the curing of the resin composition. One embodiment of the aqueous polyurethane resin dispersion composition of the present invention is a composition in which the polyurethane resin (A) and the curing agent (B) are dispersed in an aqueous medium.

As the curing agent (B), a known compound can be used. Examples include polyisocyanate compounds, polycarbodiimide compounds, amino resins, epoxy group-containing compounds, aziridine compounds, etc.

As the curing agent (B), polyisocyanate compounds capable of reacting with the hydroxyl groups in the polyurethane resin (A), amino resins capable of reacting with the hydroxyl groups in the polyurethane resin (A), and polycarbodiimide compounds capable of reacting with the acidic groups in the polyurethane resin (A) can be suitably used.

The curing agent (B) may be used alone or in combination with multiple types.

The polyisocyanate compound is a compound having at least two isocyanate groups in one molecule. For example, the same compounds as those described in the polyisocyanate (Ab) above can be used. Among them, aliphatic isocyanate compounds and alicyclic isocyanate compounds are preferred.

The polyisocyanate compound may have an isocyanato group blocked with a blocking agent. Examples of blocking agents include phenol-based agents such as phenol and cresol, aliphatic alcohol-based agents such as methanol and ethanol, active methylene-based agents such as dimethyl malonate and acetylacetone, mercaptan-based agents such as butyl mercaptan and dodecyl mercaptan, acid amide-based agents such as acetanilide and acetate amide, lactam-based agents such as ε-caprolactam and δ-valerolactam, acid imide-based agents such as succinimide and maleimide, oxime-based agents such as acetaldoxime, acetoneoxime, and methylethylketoxime, amine-based agents such as diphenylaniline, aniline, ethyleneimine, and dimethylpyrazole, and hydroxycarboxylic acids such as hydroxypivalic acid and dimethylolpropionic acid. Among these, oxime-based blocking agents, active methylene-based blocking agents, and amine-based blocking agents are preferred from the viewpoint of improving the smoothness of the coating film, and pyrazole is more preferred.

Commercially available products can be used as the polyisocyanate compound. For example, the EASAQUA (registered trademark) series manufactured by Vencorex can be used, but the present invention is not limited to these examples.

Examples of the polycarbodiimide compound include N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-tert-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-dicyclohexylcarbodiimide, and N,N'-di-p-toluylcarbodiimide. Examples of such carbodiimides include the Carbodilite series manufactured by Nisshinbo Chemical Inc., but are not limited to these examples.

As the amino resin, a partially methylolated amino resin or a fully methylolated amino resin obtained by the reaction of an amino component with an aldehyde component can be used. Examples of the amino component include melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide. Examples of the aldehyde component include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.

The methylolated amino resin may also be used in which the methylol groups are partially or completely etherified with a suitable alcohol. Examples of alcohols used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutanol, and 2-ethylhexanol.

As the amino resin, melamine resin is preferred, and more preferred are methyl etherified melamine resins in which the methylol groups of partially or fully methylolated melamine resins are partially or completely etherified with methyl alcohol, butyl etherified melamine resins in which the methylol groups of partially or fully methylolated melamine resins are partially or completely etherified with butyl alcohol, and methyl-butyl mixed etherified melamine resins in which the methylol groups of partially or fully methylolated melamine resins are partially or completely etherified with methyl alcohol and butyl alcohol.

Commercially available amino resins can be used. For example, the U-BAN (registered trademark) series manufactured by Mitsui Chemicals, Inc. can be used, but the present invention is not limited to these examples.

<Production of Aqueous Polyurethane Resin Dispersion Composition>
The aqueous polyurethane resin dispersion composition according to the present invention contains a polyurethane resin (A) and an aqueous medium, and may contain a curing agent (B).
The aqueous medium is water or a mixed medium of water and a hydrophilic organic solvent.
Examples of water include tap water, ion-exchanged water, distilled water, and ultrapure water.
Examples of hydrophilic organic solvents include ketones such as acetone and ethyl methyl ketone; pyrrolidones such as N-methylpyrrolidone and N-ethylpyrrolidone; ethers such as diethyl ether and dipropylene glycol dimethyl ether; alcohols such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol, and diethylene glycol; amides such as β-alkoxypropionamide, typified by "KJCMPA(R)-100" manufactured by KJ Chemical Co.; and hydroxyl group-containing tertiary amines such as 2-(dimethylamino)-2-methyl-1-propanol (DMAP).
The amount of the hydrophilic organic solvent in the aqueous medium is preferably from 0 to 20% by mass.
The pH of the aqueous polyurethane resin dispersion is preferably from 5.0 to 9.0.

When mixing polyurethane resin (A) and curing agent (B), the solids weight ratio of the curing agent (B) to the solids weight of polyurethane resin (A) is preferably (B)/(A) = 0.10 to 0.65, more preferably 0.13 to 0.63, from the viewpoint of improving storage stability and alcohol resistance of the coating film. More specifically, the ratio of the two per unit hydroxyl value (1 mg KOH/g) of polyurethane resin (A) is preferably 0.010 to 0.065, more preferably 0.013 to 0.063, from the viewpoint of further improving alcohol resistance.

The aqueous polyurethane resin dispersion composition contains the aqueous polyurethane resin dispersion as an essential component, but may also contain other resins and/or other additives as necessary.

Examples of the other resins include polyester resins, acrylic resins, polyether resins, polycarbonate resins, polyurethane resins, epoxy resins, alkyd resins, polyolefin resins, vinyl chloride resins, etc. Among them, polyester resins, acrylic resins, and polyolefin resins are preferred, and it is more preferred to add at least one selected from polyester resin emulsions, acrylic resin emulsions, and polyolefin resin emulsions, and it is even more preferred to add acrylic resin emulsions. These may be used alone or in combination.
The emulsion refers to a state in which a resin is dispersed in water or in a mixed medium of an organic solvent and water.

Examples of the other additives that can be used include surface conditioners, emulsifiers, thickeners, urethane catalysts, fillers, foaming agents, pigments, dyes, oil repellents, film-forming assistants, hollow foams, flame retardants, defoamers, leveling agents, anti-blocking agents, UV absorbers, light stabilizers, plasticizers, and anti-settling agents. These additives may be used alone or in combination of two or more.

Surface conditioners that can be used without particular restrictions include those called surface conditioners, leveling agents, wetting agents, defoamers, etc., which have the ability to eliminate defects in coating films caused by changes in viscosity, changes in surface tension, and foam generation that generally accompany high molecular weight. For example, various surface conditioners, leveling agents, wetting agents, defoamers, etc., such as acrylic, vinyl, silicone, fluorine, cellulose, natural wax, and water-soluble organic solvents, as well as surfactants are preferred, and among these, wetting agents are preferred.

As the pigment, known color pigments, extender pigments, and luster pigments can be used. Examples of color pigments include inorganic pigments such as iron oxide, titanium oxide, zinc oxide, molybdenum red, cobalt blue, and carbon black, and organic pigments such as quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, and azo pigments. Examples of extender pigments include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white. Examples of luster pigments include aluminum, copper, zinc, brass, nickel, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, and mica coated with iron oxide or titanium oxide.

The film-forming assistant is generally a hydrophilic compound that has the effect of promoting film formation when forming a coating film using an aqueous coating agent. Examples of the film-forming assistant include pyrrolidone compounds such as N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-isopropylpyrrolidone, N-butylpyrrolidone, N-cyclohexylpyrrolidone, N-octylpyrrolidone, N-phenylpyrrolidone, and vinylpyrrolidone; alcohol compounds such as methanol, ethanol, isopropanol, n-butanol, and n-hexanol; glycol compounds such as propylene glycol, diethylene glycol, propylene glycol, triethylene glycol, and polyethylene glycol; and the like. Among these, pyrrolidone compounds are preferred.
The film-forming auxiliary can also serve as the aqueous medium in which the polyurethane resin (A) is dispersed.

The method for producing the aqueous polyurethane resin dispersion composition of the present invention is not particularly limited, and any known production method can be used. For example, the aqueous polyurethane resin dispersion is produced by stirring and mixing the curing agent (B) and/or the various additives described above.

<Paint composition, coating composition>
The present invention relates to a paint composition and a coating composition containing an aqueous polyurethane resin dispersion. The paint composition and the coating composition of the present invention are compositions containing an aqueous polyurethane resin dispersion and used for paint applications and coating applications.

Aqueous dispersions and/or aqueous solutions of resins other than the resins contained in the aqueous polyurethane resin dispersion can be added to the paint composition and coating composition. Examples of such other resins include polyester resins, acrylic resins, polyether resins, polycarbonate resins, polyurethane resins, epoxy resins, alkyd resins, polyolefin resins, and vinyl chloride resins. These may be used alone or in combination. It is preferable that the other resins have one or more hydrophilic groups. Examples of hydrophilic groups include hydroxyl groups, carboxyl groups, sulfonic acid groups, and polyethylene glycol groups.

The other resin is preferably at least one selected from the group consisting of polyester resin, acrylic resin, and polyolefin resin.

Polyester resins can usually be produced by an esterification reaction or transesterification reaction between an acid component and an alcohol component. As the acid component, compounds that are usually used as acid components in the production of polyester resins can be used. As the acid component, for example, aliphatic polybasic acids, alicyclic polybasic acids, aromatic polybasic acids, etc. can be used.

Acrylic resin is a compound that has polymerization units derived from "(meth)acrylic monomers" that have one or more "(meth)acryloyl groups" in the molecule. Acrylic resins are usually obtained by polymerizing one or more (meth)acrylic monomers.

Examples of the (meth)acrylic monomer include 2-ethylhexyl (meth)acrylate, methyl (meth)acrylate, butyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol-polypropylene glycol mono(meth)acrylate, poly(ethylene glycol-tetramethylene glycol) mono(meth)acrylate, poly(propylene glycol-tetramethylene glycol) mono(meth)acrylate, Examples of (meth)acrylic acid alkyl esters include acrylate, methoxypolyethylene glycol mono(meth)acrylate, octoxypolyethylene glycol-polypropylene glycol mono(meth)acrylate, lauroxypolyethylene glycol mono(meth)acrylate, and stearoxypolyethylene glycol mono(meth)acrylate; and (meth)acrylic acid aryl esters such as phenoxyethyl (meth)acrylate, nonylphenoxypolyethylene glycol mono(meth)acrylate, nonylphenoxypolypropylene glycol polyethylene glycol mono(meth)acrylate, phenoxypolyethylene glycol mono(meth)acrylate, and phenoxypolypropylene glycol polyethylene glycol mono(meth)acrylate.

Examples of polyether resins include polymers or copolymers having ether bonds, such as polyoxyethylene-based polyethers, polyoxypropylene-based polyethers, polyoxybutylene-based polyethers, and polyethers derived from aromatic polyhydroxy compounds such as bisphenol A or bisphenol F.

Polycarbonate resins include polymers made from bisphenol compounds, such as bisphenol A polycarbonate.

Polyurethane resins include resins having urethane bonds obtained by reacting various polyol components, such as acrylic polyols, polyester polyols, polyether polyols, and polycarbonate polyols, with polyisocyanates.

Epoxy resins include resins obtained by reacting bisphenol compounds with epichlorohydrin. Examples of bisphenol compounds include bisphenol A and bisphenol F.

Examples of alkyd resins include alkyd resins obtained by reacting polybasic acids such as phthalic acid, terephthalic acid, and succinic acid with polyhydric alcohols and further with modifiers such as oils and oil-based fatty acids (soybean oil, linseed oil, coconut oil, stearic acid, etc.) and natural resins (rosin, amber, etc.).

Examples of polyolefin resins include polyolefin resins obtained by polymerizing or copolymerizing an olefin monomer with other monomers according to a conventional polymerization method, and dispersing the polyolefin resin in water using an emulsifier, or resins obtained by emulsion polymerizing an olefin monomer with other monomers. In some cases, the polyolefin resin may be chlorinated to use a so-called chlorinated polyolefin modified resin.

Examples of olefin monomers include α-olefins such as ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-hexene, 1-decene, and 1-dodecene; and conjugated or non-conjugated dienes such as butadiene, ethylidenenorbornene, dicyclopentadiene, and 1,5-hexadiene. These monomers may be used alone or in combination.

Examples of other monomers that can be copolymerized with olefin monomers include styrene, vinyl acetate, vinyl alcohol, maleic acid, citraconic acid, itaconic acid, maleic anhydride, citraconic anhydride, and itaconic anhydride. These monomers may be used alone or in combination.

The paint composition and coating composition may contain, as necessary, conventional additives such as surface conditioners, emulsifiers, curing agents, thickeners, urethane catalysts, fillers, foaming agents, pigments, dyes, oil repellents, hollow foams, flame retardants, defoamers, leveling agents, antiblocking agents, UV absorbers, light stabilizers, plasticizers, and antisettling agents. A combination of these may be used.

The method for producing the paint composition and the coating composition is not particularly limited, and any known production method can be used. In general, the paint composition and the coating composition are produced by mixing the aqueous polyurethane resin dispersion composition with the other resins and/or various additives described above, adding an aqueous medium, and adjusting the viscosity according to the application method.

Materials to which the paint composition can be applied or to which the coating composition can be applied include metals, plastics, inorganic materials, wood, etc., and electrocoated panels are also suitable.

Examples of methods for applying a paint composition or a coating agent composition include bell coating, spray coating, roll coating, shower coating, and dip coating. After painting or coating, other materials can be applied to the painted or coated surface. Examples of methods for applying such undercoat compositions include inkjet printing, flexographic printing, gravure printing, reverse offset printing, sheet-fed screen printing, rotary screen printing, air spray coating, bell coating, and electrostatic coating.

<Coating film>
A coating film can be obtained by drying the aqueous polyurethane resin dispersion of the present invention.
The thickness of the coating film obtained from the aqueous polyurethane resin dispersion is not particularly limited, but is preferably adjusted to 0.5 to 200 μm, more preferably 1 to 100 μm, even more preferably 5 to 50 μm, and even more preferably 10 to 40 μm.

The alcohol resistance of the coating film obtained from the aqueous polyurethane resin dispersion of the present invention is preferably 15 or more round trips of rubbing until the coating film breaks, and more preferably 17 or more round trips. The alcohol resistance is measured by the method described in the Examples. Furthermore, when the coating film obtained using the aqueous polyurethane resin dispersion of the present invention is wiped with a sheet containing alcohol, alcohol resistance is necessary to function as a coating agent. In this case, a spot test in which the coating film is simply soaked in alcohol and left to stand cannot provide a sufficient evaluation, and the rubbing test described below is better for evaluating the performance as a coating agent.

The adhesion of the coating film obtained from the aqueous polyurethane resin dispersion of the present invention, as measured by the method described in the Examples, is preferably 95% or more, and more preferably 98% or more, as the percentage of the coating film that did not peel off.

<Method of producing coating film>
A coating film can be obtained by applying the aqueous polyurethane resin dispersion of the present invention and then drying or curing it. It is preferable to apply the paint composition or coating composition to a target material and then dry or cure the composition by heating to obtain a coating film.
The heating method includes a heating method using the heat of reaction of the composition itself, a heating method in which the paint composition or coating composition and the material to which it is applied are actively heated, etc. Active heating includes a method in which the paint composition or coating composition and the material to which it is applied are placed in a hot air oven, an electric furnace, or an infrared induction heating furnace and heated.

The composition of the present invention can be dried or cured by heating to a temperature of 20° C. or higher and preferably 100° C. or lower, more preferably 80° C. or lower.
Specifically, the coating material composition can be applied to various plastic substrates such as electrodeposition coated surfaces, steel plates, wood, polycarbonate resins, acrylic resins, polyethylene terephthalate (PET) resins, and acrylonitrile butadiene styrene (ABS) resins, using a spray, brush, applicator, bar coater, or the like, and then dried or cured by a method of retaining the applied coating in an oven, heating tank, or the like at 100° C. or lower, preferably 80° C., for 1 to 120 minutes, preferably 1 to 60 minutes, and more preferably 1 to 45 minutes.
When used as a primer, base coat, or the like in a multi-layer coating film, after application to the various substrates described above, it is possible to hold, for example, at 20 to 80°C for 1 to 30 minutes, preferably 1 to 10 minutes, and more preferably 2 to 6 minutes, and then, as an optional component, another type of base coat is applied and treated at the same temperature and time, after which a top coat (which may be called a clear coat depending on the application) is applied and heated at 100°C or less, preferably 80°C or less, for 10 to 120 minutes, more preferably 20 to 90 minutes, and even more preferably 30 to 60 minutes.
One embodiment of the present invention is a method for obtaining a coating film, comprising the step of subjecting an aqueous polyurethane resin dispersion to a temperature of from 20 to 100°C.

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these.

[Production of aqueous polyurethane resin dispersion]
[Synthesis Example 1]
Aqueous polyurethane resin dispersion (U1)
ETERNACOLL (registered trademark) UM90 (1/3) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=1:3 with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (29.5 g), and hydrogenated MDI (204 g) were heated in dipropylene glycol dimethyl ether (DMM, 75.2 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (22.3 g) was added and mixed thereto, and 358 g of the mixture was added to water (619 g) under strong stirring. Next, 35% by mass of 2-methyl-1,5-pentanediamine aqueous solution (69.4 g) and 35% by mass of 2-(2-aminoethylamino)ethanol aqueous solution (8.41 g) were added to obtain an aqueous polyurethane resin dispersion (U1).

[Synthesis Example 2]
Aqueous polyurethane resin dispersion (U2)
ETERNACOLL (registered trademark) UM90 (1/3) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=1:3 with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (29.0 g), and hydrogenated MDI (202 g) were heated in dipropylene glycol dimethyl ether (DMM, 73.0 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (21.9 g) was added and mixed thereto, and 354 g of the mixture was added to water (615 g) under strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (59.5 g) and a 35% by mass aqueous solution of 2-(2-aminoethylamino)ethanol (16.7 g) were added to obtain an aqueous polyurethane resin dispersion (U2).

[Synthesis Example 3]
Aqueous polyurethane resin dispersion (U3)
ETERNACOLL (registered trademark) UM90 (3/1) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=3:1 with a carbonate ester, 190 g), 2,2-dimethylolpropionic acid (27.6 g), and hydrogenated MDI (180 g) were heated in dipropylene glycol dimethyl ether (DMM, 143 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (20.8 g) was added and mixed thereto, of which 421 g was added to water (585 g) under strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (54.6 g) and a 35% by mass aqueous solution of 2-(2-aminoethylamino)ethanol (8.56 g) were added to obtain an aqueous polyurethane resin dispersion (U3).

[Synthesis Example 4]
Aqueous polyurethane resin dispersion (U4)
ETERNACOLL (registered trademark) UC100 (manufactured by Ube Industries; number average molecular weight 1000; hydroxyl value 110 mgKOH/g; polycarbonate diol obtained by reacting 1,4-cyclohexanedimethanol with carbonate ester, 180 g), 2,2-dimethylolpropionic acid (28.3 g), and hydrogenated MDI (191 g) were heated in dipropylene glycol dimethyl ether (DMM, 145 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (21.3 g) was added and mixed, and 395 g of the mixture was added to water (440 g) under strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (61.4 g) and a 35% by mass aqueous solution of 2-(2-aminoethylamino)ethanol (8.00 g) were added to obtain an aqueous polyurethane resin dispersion (U4).

[Synthesis Example 5]
Aqueous polyurethane resin dispersion (U5)
ETERNACOLL (registered trademark) UM90 (3/1) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=3:1 with a carbonate ester, 152 g), PTMG2000 (manufactured by Mitsubishi Chemical; number average molecular weight 1955; hydroxyl value 57.4 mg KOH/g; polytetramethylene ether glycol, 38.0 g), 2,2-dimethylolpropionic acid (26.5 g), and hydrogenated MDI (167 g) were heated in dipropylene glycol dimethyl ether (DMM, 137 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (20.0 g) was added thereto and mixed, and 405 g of the mixture was added to water (563 g) under strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (50.0 g) and a 35% by mass aqueous solution of 2-(2-aminoethylamino)ethanol (8.23 g) were added thereto to obtain an aqueous polyurethane resin dispersion (U5).

[Synthesis Example 6]
Aqueous polyurethane resin dispersion (U6)
ETERNACOLL (registered trademark) UH100 (manufactured by Ube Industries; number average molecular weight 1,000; hydroxyl value 110 mgKOH/g; polycarbonate diol obtained by reacting 1,6-hexanediol with carbonate ester, 180 g), 2,2-dimethylolpropionic acid (27.9 g), and hydrogenated MDI (188 g) were heated in dipropylene glycol dimethyl ether (DMM, 72.0 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (21.0 g) was added and mixed thereto, and 367 g of the mixture was added to water (637 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (68.4 g) and a 35% by mass aqueous solution of 2-(2-aminoethylamino)ethanol (8.60 g) were added to obtain an aqueous polyurethane resin dispersion (U6).

[Synthesis Example 7]
Aqueous polyurethane resin dispersion (U7)
ETERNACOLL (registered trademark) UM90 (1/3) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=1:3 with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (29.1 g), and hydrogenated MDI (202 g) were heated in dipropylene glycol dimethyl ether (DMM, 75.2 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (22.0 g) was added and mixed thereto, and 356 g of the mixture was added to water (617 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (78.3 g) was added to obtain an aqueous polyurethane resin dispersion (U7).

[Synthesis Example 8]
Aqueous polyurethane resin dispersion (U8)
ETERNACOLL (registered trademark) UM90 (3/1) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=3:1 with a carbonate ester, 1500 g), 2,2-dimethylolpropionic acid (220 g), and hydrogenated MDI (1450 g) were heated in dipropylene glycol dimethyl ether (DMM, 1350 g) in the presence of dibutyltin dilaurate (2.6 g) under a nitrogen atmosphere at 80 to 90° C. for 6 hours. The reaction mixture was cooled to 80° C., and triethylamine (149 g) was added and mixed thereto. Of the mixture, 4360 g was added to water (6900 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (626 g) was added to obtain an aqueous polyurethane resin dispersion (U8).

[Synthesis Example 9]
Aqueous polyurethane resin dispersion (U9)
ETERNACOLL (registered trademark) UM90 (3/1) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=3:1 with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (26.8 g), and hydrogenated MDI (173 g) were heated in dipropylene glycol dimethyl ether (DMM, 137 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (20.2 g) was added and mixed thereto, and 430 g of the mixture was added to water (594 g) under strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (30.5 g) and a 35% by mass aqueous solution of 2-(2-aminoethylamino)ethanol (31.5 g) were added to obtain an aqueous polyurethane resin dispersion (U9).

[Synthesis Example 10]
ETERNACOLL (registered trademark) UM90 (1/3) (manufactured by Ube Industries; number average molecular weight 916; hydroxyl value 123 mg KOH/g; polycarbonate diol obtained by reacting a polyol mixture having a molar ratio of 1,4-cyclohexanedimethanol:1,6-hexanediol=1:3 with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (29.1 g), and hydrogenated MDI (202 g) were heated in dipropylene glycol dimethyl ether (DMM, 75.2 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95° C. for 5 hours. The reaction mixture was cooled to 80° C., and triethylamine (22.0 g) was added and mixed thereto, and 356 g of the mixture was added to water (617 g) under strong stirring. Then, 35% by mass of 2-methyl-1,5-pentanediamine aqueous solution (48.6 g) and 35% by mass of diethylenetriamine aqueous solution (17.6 g) were added to obtain an aqueous polyurethane resin dispersion (U10). The hydroxyl value of the polyurethane resin in the dispersion was 0 mgKOH/g.

[Example 1]
For 100 parts by mass of the aqueous polyurethane resin dispersion U1, 10 parts by mass of EASAQUA XD870 manufactured by Vencorex as an isocyanate curing agent, 8.3 parts by mass of purified water, 5.0 parts by mass of N-methylpyrrolidone, 4.5 parts by mass of a red pigment (EMF Pink 2B-1 manufactured by Toyo Color Co., Ltd.), and 0.6 parts by mass of a surface conditioner (BYK-Chemie; BYK-345) were blended to produce an aqueous polyurethane resin dispersion composition. The content of the alicyclic structure derived from the polycarbonate polyol and the hydroxyl value of the aqueous polyurethane resin dispersion compositions obtained in the examples and comparative examples are summarized in Table 1.

[Example 2]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Example 1, except that the aqueous polyurethane resin dispersion U2 was used instead of the aqueous polyurethane resin dispersion U1.

[Example 3]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Example 1, except that the aqueous polyurethane resin dispersion U3 was used instead of the aqueous polyurethane resin dispersion U1.

[Example 4]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Example 1, except that the aqueous polyurethane resin dispersion U4 was used instead of the aqueous polyurethane resin dispersion U1.

[Example 5]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Example 1, except that the aqueous polyurethane resin dispersion U5 was used instead of the aqueous polyurethane resin dispersion U1.

[Comparative Example 1]
An aqueous polyurethane resin dispersion composition was produced by blending 10 parts by mass of EASAQUA XD870 manufactured by Vencorex Corporation as an isocyanate curing agent, 8.3 parts by mass of purified water, 5.0 parts by mass of N-methylpyrrolidone, 4.5 parts by mass of a red pigment (EMF Pink 2B-1 manufactured by Toyo Color Co., Ltd.), and 0.6 parts by mass of a surface conditioner (BYK-Chemie; BYK-345) with 100 parts by mass of the aqueous polyurethane resin dispersion U6.

[Comparative Example 2]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Comparative Example 1, except that the aqueous polyurethane resin dispersion U7 was used instead of the aqueous polyurethane resin dispersion U6.

[Comparative Example 3]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Comparative Example 1, except that the aqueous polyurethane resin dispersion U8 was used instead of the aqueous polyurethane resin dispersion U6.

[Comparative Example 4]
An aqueous polyurethane resin dispersion composition was produced in the same manner as in Comparative Example 1, except that the aqueous polyurethane resin dispersion U9 was used instead of the aqueous polyurethane resin dispersion U6.

[Manufacturing method of test sample]
For each evaluation test described later, test pieces were prepared by the following method. Each of the aqueous polyurethane resin dispersion compositions of Examples 1 to 5 and Comparative Examples 1 to 4 was applied to a polycarbonate plate (70 mm x 150 mm, thickness 2.0 mm, manufactured by Engineering Test Service Co., Ltd.) using a #18 bar coater, and heated at 90°C for 5 minutes to obtain a test sample in which a coating film was formed on the polycarbonate plate.

[Evaluation of alcohol resistance]
The obtained test samples were subjected to a solvent rubbing test to evaluate the alcohol resistance. The solvent rubbing test was performed by applying a load of 700 g to a wafer impregnated with 80% by mass ethanol, rubbing the surface of each test sample back and forth, and measuring the number of back and forth strokes at the time when the coating film was found to break. The larger the number of back and forth strokes, the higher the alcohol resistance.

[Adhesion evaluation]
The obtained test samples were used to carry out a cross-cut peel test to evaluate adhesion. In the cross-cut peel test, the coating film was cut at 2 mm intervals in the vertical and horizontal directions in an area of 20 mm x 20 mm, and an adhesive tape was applied to the coating film. The adhesive tape was then peeled upward at a right angle to the substrate, and the proportion of coating film that did not peel off was evaluated. The larger the value, the higher the adhesion. In all of the samples of the examples, the proportion of coating film that did not peel off in this test was 100%. This shows that the composition of the present invention has good adhesion when used as a coating film.

From the results in Table 1, it can be seen that in Examples 1 to 5, the solvent rubbing test was performed 15 times or more, and therefore the coating film of polyurethane resin (A) containing polycarbonate polyol (Aa) having an alicyclic structure exhibits good alcohol resistance. On the other hand, from Comparative Example 1, it can be seen that when polyurethane resin (A) does not have a structure derived from polycarbonate polyol (Aa) having an alicyclic structure, the alcohol resistance decreases. From Comparative Examples 2 and 3, it can be seen that when polyurethane resin (A) does not have a structure derived from hydroxyl group-containing polyamine (Ad), the alcohol resistance decreases. From Comparative Example 4, it can be seen that when the hydroxyl value of polyurethane resin (A) exceeds 15 mgKOH/g, the alcohol resistance decreases.

[Reference Example 1]
A surface conditioner (BYK-345, manufactured by BYK-Chemie) was mixed in an amount of 0.5 parts by mass per 100 parts by mass of the aqueous polyurethane resin dispersion U7 to produce an aqueous polyurethane resin dispersion composition. The aqueous polyurethane resin dispersion composition thus obtained was applied to a polyethylene terephthalate film (Lumirror, manufactured by Toray Industries, Inc.) using a #20 bar coater, and heated at 80°C for 10 minutes to obtain a laminate 1 in which a coating film was laminated on a polyethylene terephthalate film plate.
The obtained laminate 1 was subjected to a solvent rubbing test to evaluate the alcohol resistance. In the solvent rubbing test, a wafer impregnated with 40% by mass of ethanol was rubbed back and forth 50 times on the surface of the test sample with a load of 1,500 g. When the appearance of the coating film was observed, no whitening was observed.
On the other hand, a spot test was performed to evaluate the alcohol resistance using the obtained laminate 1. A wafer impregnated with 80% by mass of ethanol was placed on the laminate and left at room temperature for 25 hours. When the appearance of the coating film was checked, whitening was observed.

[Reference Example 2]
A laminate sample 2 was obtained in the same manner as in Reference Example 1, except that the aqueous polyurethane resin dispersion U7 was replaced with the aqueous polyurethane resin dispersion U10.
A solvent rubbing test was carried out using laminate sample 2 in the same manner as in Reference Example 1 to evaluate the alcohol resistance, and whitening was observed in the coating film.
A spot test was carried out using laminate sample 2 in the same manner as in Reference Example 1 to evaluate the alcohol resistance, and no whitening was observed in the coating film.
From the results of Reference Examples 1 and 2 above, when a spot test and a rubbing test were carried out using the aqueous polyurethane resin dispersion, it was found that the evaluation results of Reference Examples 1 and 2 were reversed.

The aqueous polyurethane resin dispersion of the present invention has excellent alcohol resistance and can be widely used as a paint composition, a coating composition, etc.

Claims (12)

a polyurethane resin (A) having a structure derived from a polycarbonate polyol (Aa) having an alicyclic structure, a structure derived from a polyisocyanate (Ab), a structure derived from an acidic group-containing polyol (Ac), and a structure derived from a hydroxyl group-containing polyamine (Ad) dispersed in an aqueous medium;
The hydroxyl value of the polyurethane resin (A) is in the range of 3.0 to 15 mgKOH/g.
Aqueous polyurethane resin dispersion. The aqueous polyurethane resin dispersion according to claim 1, further comprising a structure derived from a chain extender (Ae). The aqueous polyurethane resin dispersion according to claim 1 or 2, wherein the content of the alicyclic structure in the polycarbonate polyol (Aa) having an alicyclic structure is 1 to 50 mass% based on the total amount of the polycarbonate polyol (Aa). The aqueous polyurethane resin dispersion according to any one of claims 1 to 3, wherein the polycarbonate polyol (Aa) having an alicyclic structure contains a cyclohexane ring. The aqueous polyurethane resin dispersion according to any one of claims 1 to 4, wherein the polyisocyanate (Ab) is at least one selected from the group consisting of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate. The aqueous polyurethane resin dispersion according to any one of claims 1 to 5, wherein the hydroxyl group-containing polyamine (Ad) is at least one selected from the group consisting of 3,5-diaminobenzyl alcohol, 1,3-diamino-2-propanol, 2,2'-(ethylene bisimino) bisethanol, N-(2-hydroxyethyl)-N'-(2-aminoethyl) ethylenediamine, N-(3-hydroxypropyl) ethylenediamine, 2-[bis(2-aminoethyl)amino]ethanol, 1-[2-[(2-aminoethyl)amino]ethyl]amino-2-propanol, N,N-bis(hydroxyethyl)diethylenetriamine, N1,N4-bis(hydroxyethyl)diethylenetriamine, N1-(2-hydroxypropyl)triethylenetetraamine, N4-(2-hydroxypropyl)triethylenetetraamine, N-(2-hydroxypropyl)triethylenetetraamine, and 2-(2-aminoethylamino)ethanol. The aqueous polyurethane resin dispersion according to claim 6, wherein the hydroxyl-containing polyamine (Ad) is 2-(2-aminoethylamino)ethanol. The aqueous polyurethane resin dispersion according to any one of claims 1 to 7, wherein the content of the alicyclic structure contained in the polyurethane resin (A) is 30 to 50 mass% on a solids basis with respect to the total amount of the polyurethane resin (A). A coating composition containing the aqueous polyurethane resin dispersion according to any one of claims 1 to 8. A coating composition containing the aqueous polyurethane resin dispersion according to any one of claims 1 to 8. A coating film obtained by drying the aqueous polyurethane resin dispersion according to any one of claims 1 to 8. A method for producing a coating film, comprising a step of subjecting the aqueous polyurethane resin dispersion according to any one of claims 1 to 8 to a temperature of 20 to 100°C.