阅读说明：本技术 聚尿烷水分散体、聚尿烷水分散体的制造方法、水系涂料组合物及涂膜 (Aqueous polyurethane dispersion, process for producing aqueous polyurethane dispersion, aqueous coating composition, and coating film ) 是由 后藤充朗 于 2018-06-21 设计创作，主要内容包括：一种聚尿烷水分散体,含有：水；以及含OH基聚尿烷,所述含OH基聚尿烷为在分子链末端具有OH基的含OH基聚尿烷与叔胺的中和物。在上述聚尿烷水分散体中,含OH基聚尿烷包含：来自规定的多元醇的结构单元(A1)；来自规定的第一二醇的结构单元(B1)；来自多价醇的结构单元(C1),所述多价醇的规定的每分子的官能团的数量超过2且为4以下；及来自第二二醇的结构单元(D1),所述第二二醇具有羧基。含OH基聚尿烷的重均分子量为16000以上且140000以下。(An aqueous polyurethane dispersion comprising: water; and OH group-containing polyurethane which is a neutralized product of OH group-containing polyurethane having an OH group at a molecular chain end and a tertiary amine. In the above polyurethane aqueous dispersion, the OH group-containing polyurethane comprises: a structural unit (A1) derived from a predetermined polyol; a structural unit (B1) derived from a prescribed first diol; a structural unit (C1) derived from a polyvalent alcohol having a number of prescribed functional groups per molecule of more than 2 and 4 or less; and a structural unit (D1) derived from a second diol having a carboxyl group. The weight average molecular weight of the OH group-containing polyurethane is 16000 or more and 140000 or less.)

1. An aqueous polyurethane dispersion comprising:

water; and

a neutralized product of an OH group-containing polyurethane having an OH group at a molecular chain terminal and a tertiary amine dispersed in the water;

the OH group-containing polyurethane contains in the molecular chain:

a structural unit (a1) derived from a polyol (a) which is at least one of a polycarbonate polyol and a polyester polyol and has a number average molecular weight of more than 500 and not more than 5000;

a structural unit (B1) derived from a first diol (B) having a number average molecular weight of 500 or less and having no carboxyl group;

a structural unit (C1) derived from a polyvalent alcohol (C) having a number-average molecular weight of 500 or less and a number of functional groups per molecule of more than 2 and 4 or less;

a structural unit (D1) from a second diol (D) having a carboxyl group; and

a structural unit (E1) derived from a diisocyanate component (E) comprising xylylene diisocyanate (Ea), and a structural unit (E1) comprising a structural unit (E1a) derived from xylylene diisocyanate (Ea),

the weight average molecular weight of the OH group-containing polyurethane is 16000 or more and 140000 or less.

2. The aqueous polyurethane dispersion according to claim 1,

the proportion of the structural unit (A1) derived from the polyol (A) in the molecular chain of the OH group-containing polyurethane is 10 to 60 mass% in terms of mass.

3. The aqueous polyurethane dispersion according to claim 1 or claim 2,

assuming that all OH groups contained in all polyols from which the structural unit (A1), the structural unit (B1), the structural unit (C1) and the structural unit (D1) are derived are reacted with all NCO groups contained in diisocyanate from which the structural unit (E1) is derived, and the total number of OH groups contained in a virtual OH group-containing polyurethane formed by the reaction is defined as a value f, the average value of the value f per 1000 calculated molecular weight of the virtual OH group-containing polyurethane is defined as a value fI.e. f₁₀₀₀The value is 2.1 or more and 2.9 or less.

4. The aqueous polyurethane dispersion according to claim 1 to claim 3,

the OH group-containing polyurethane has an acid value of 14 to 55 inclusive.

5. The aqueous polyurethane dispersion according to claim 1 to 4,

the structural unit (E1) further includes a structural unit (E1b), and the structural unit (E1b) is derived from at least one diisocyanate selected from the group consisting of an aromatic diisocyanate compound other than xylylene diisocyanate (Ea), an alicyclic diisocyanate compound, and an aliphatic diisocyanate compound.

6. The aqueous polyurethane dispersion according to claim 1 to 5,

the polycarbonate polyol mainly comprises at least one of 1, 6-hexanediol and 1, 4-cyclohexanedimethanol,

the polyester polyol is mainly composed of lactone.

7. The aqueous polyurethane dispersion according to claim 1 to 6,

the structural unit (C1) derived from a polyvalent alcohol is mainly composed of a structural unit composed of trimethylolpropane.

8. The aqueous polyurethane dispersion according to claim 1 to 7,

the structural unit (B1) derived from the first diol is mainly composed of a structural unit composed of 1, 4-cyclohexanedimethanol.

9. A method for producing an aqueous polyurethane dispersion according to any one of claims 1 to 8, comprising:

a polyurethane synthesis step (1) of reacting the polyol (a), the first diol (B), the polyvalent alcohol (C), the second diol (D), and the diisocyanate component (E) to synthesize the OH group-containing polyurethane having a weight average molecular weight of 16000 or more and 140000 or less;

a neutralization step (2) for neutralizing the OH group-containing polyurethane synthesized by the neutralization step with a neutralizing agent comprising the tertiary amine; and

and a production step (3) of dispersing the neutralized product formed in the neutralization step in water to produce an aqueous polyurethane dispersion in which the neutralized product is dispersed in water.

10. The method for producing an aqueous polyurethane dispersion according to claim 9,

the proportion of the structural unit (a1) derived from the polyol (a) in the entire OH group-containing polyurethane synthesized in the polyurethane synthesis step (1) is 10 mass% or more and 60 mass% or less in terms of mass ratio.

11. The method for producing an aqueous polyurethane dispersion according to claim 9 or claim 10,

in the OH group-containing polyurethane synthesized in the polyurethane synthesis step (1), when it is assumed that all OH groups contained in all polyols from which the structural unit (A1), the structural unit (B1), the structural unit (C1) and the structural unit (D1) are derived react with all NCO groups contained in diisocyanate from which the structural unit (E1) is derived, and the total number of OH groups contained in a virtual OH group-containing polyurethane formed by the reaction is defined as a value f, the value f is an average value of the values f per 1000 calculated molecular weights of the virtual OH group-containing polyurethane₁₀₀₀The value is 2.1 or more and 2.9 or less.

12. The method for producing an aqueous polyurethane dispersion according to any one of claims 9 to 11,

in the polyurethane synthesis step (1), the reaction is carried out so that the OH group-containing polyurethane has an acid value of 14 to 55 inclusive.

13. The method for producing an aqueous polyurethane dispersion according to any one of claims 9 to 12,

the diisocyanate component (E) contains xylylene diisocyanate (Ea) and at least one diisocyanate (Eb) selected from the group consisting of aromatic diisocyanate compounds other than xylylene diisocyanate (Ea), alicyclic diisocyanate compounds and aliphatic diisocyanate compounds.

14. A water-based coating composition comprising:

an aqueous polyurethane dispersion according to any one of claims 1 to 8 as a first dispersion;

at least one dispersion of a carbodiimide crosslinking agent aqueous dispersion and a dispersion of a polyisocyanate crosslinking agent as a second dispersion, the dispersion of the carbodiimide crosslinking agent aqueous dispersion containing carbodiimide groups of 150 equivalents or more and 600 equivalents or less as nonvolatile components; the polyisocyanate crosslinking agent dispersion contains 5 to 25 mass% of isocyanate groups as nonvolatile components in terms of mass.

15. The water-based coating composition according to claim 14, comprising:

a first liquid containing said aqueous polyurethane dispersion,

a second liquid comprising at least one dispersion of the aqueous dispersion of carbodiimide crosslinker and the dispersion of polyisocyanate crosslinker.

16. The water-based coating composition according to claim 14 or claim 15, wherein,

the carbodiimide crosslinking agent contained in the aqueous dispersion of a carbodiimide crosslinking agent and the OH group-containing polyurethane contained in the aqueous dispersion of a polyurethane have an equivalent ratio N-C-N/COOH of 0.30 to 1.7.

17. The water-based coating composition according to any one of claims 14 to 16,

the equivalent ratio NCO/OH of the isocyanate group in the polyisocyanate crosslinking agent contained in the polyisocyanate crosslinking agent dispersion and the OH group in the OH group-containing polyurethane contained in the polyurethane aqueous dispersion is 0.30 or more and 2.5 or less.

18. A coating film formed by applying the aqueous polyurethane dispersion according to any one of claims 1 to 8 or the water-based coating composition according to any one of claims 14 to 17 on a substrate.

Technical Field

The present invention relates to an aqueous polyurethane dispersion, a method for producing an aqueous polyurethane dispersion, an aqueous coating composition, and a coating film. This application is based on and claims the benefit of priority No. 2017-122609 filed in japan at 22.6.2017, the entire contents of which are incorporated herein by reference.

Background

In order to protect the interior materials of vehicles and the surfaces of audio equipment, personal computers, cellular phones, and the like, a coating film is formed by applying a paint on the surface. A method of using a solvent-based urethane resin composition or a urethane-modified acrylic resin composition as such a coating material has been proposed (for example, patent documents 1 and 2).

In addition, the surface of such a coating film may be eroded by an ultraviolet absorber contained in cosmetics, sunscreen agents, or the like. As a countermeasure against this, a method of using a polyurethane composition as the coating material is proposed (for example, patent document 3).

Disclosure of Invention

Problems to be solved by the invention

In the urethane composition for protecting the surface of the substrate as described above, the appearance is impaired by the damage generated on the surface. Therefore, it is expected to have self-repairing properties, i.e., to naturally repair the damage generated. In addition, the coating film on the surface of the substrate is also expected to have resistance to ultraviolet absorbers (ultraviolet absorber resistance). In recent years, from the viewpoint of environmental protection, an aqueous dispersion containing no organic solvent as a main component is required as the coating composition.

Accordingly, an object of the present invention is to provide an environmentally friendly aqueous polyurethane dispersion that can form a coating film having self-repairability and ultraviolet absorber resistance, a method for producing the aqueous polyurethane dispersion, an aqueous coating composition, and a coating film using the aqueous coating composition.

Means for solving the problems

The aqueous polyurethane dispersions of the present application contain: water; and a neutralized product of polyurethane containing OH groups and tertiary amine dispersed in water, the polyurethane containing OH groups having OH groups at the molecular chain terminals. The OH group-containing polyurethane contains a structural unit (a1) derived from the polyol (a), a structural unit (B1) derived from the first diol (B), a structural unit (C1) derived from the polyvalent alcohol (C), a structural unit (D1) derived from the second diol (D), and a structural unit (E1) derived from the diisocyanate component (E) in the molecular chain. The polyol (A) is at least one of a polycarbonate polyol and a polyester polyol, and has a number average molecular weight of more than 500 and not more than 5000. The first diol (B) is a diol having a number average molecular weight of 500 or less and having no carboxyl group. The polyvalent alcohol (C) is a polyvalent alcohol having a number average molecular weight of 500 or less and a number of functional groups per molecule of more than 2 and 4 or less. The second diol (D) is a diol having a carboxyl group. The diisocyanate component (E) comprises xylylene diisocyanate (Ea). Further, the structural unit (E1) includes the structural unit (E1a) derived from xylylene diisocyanate (Ea). The weight average molecular weight of the OH group-containing polyurethane is 16000 or more and 140000 or less.

ADVANTAGEOUS EFFECTS OF INVENTION

The aqueous polyurethane dispersion according to the present invention can provide an environmentally friendly aqueous polyurethane dispersion that can form a coating film having self-repairability and ultraviolet absorber resistance, a method for producing the aqueous polyurethane dispersion, an aqueous coating composition, and a coating film using the aqueous polyurethane dispersion.

Drawings

Fig. 1 is a flow chart showing a typical process of a method for producing an aqueous polyurethane dispersion according to an embodiment of the present invention.

Detailed Description

[ description of embodiments of the invention of the present application ]

First, embodiments of the invention of the present application will be exemplified. The aqueous polyurethane dispersion according to the invention comprises: water; and a neutralized product of polyurethane containing OH groups and tertiary amine dispersed in water, the polyurethane containing OH groups having OH groups at the molecular chain terminals. The OH group-containing polyurethane contains a structural unit (a1) derived from the polyol (a), a structural unit (B1) derived from the first diol (B), a structural unit (C1) derived from the polyvalent alcohol (C), a structural unit (D1) derived from the second diol (D), and a structural unit (E1) derived from the diisocyanate component (E) in the molecular chain. The polyol (a) is at least one of a polycarbonate polyol and a polyester polyol, and has a number average molecular weight of more than 500 and not more than 5000. The first diol (B) is a diol having a number average molecular weight of 500 or less and having no carboxyl group. The polyvalent alcohol (C) is a polyvalent alcohol having a number average molecular weight of 500 or less and a number of functional groups per molecule of more than 2 and 4 or less. The second diol (D) is a diol having a carboxyl group. The diisocyanate component (E) comprises xylylene diisocyanate (Ea). Further, the structural unit (E1) includes the structural unit (E1a) derived from xylylene diisocyanate (Ea). The weight average molecular weight of the OH group-containing polyurethane is 16000 or more and 140000 or less. By using the polyurethane aqueous dispersion, a coating film having self-repairability and ultraviolet absorber resistance can be formed. In addition, by using water as a solvent, an environmentally friendly aqueous polyurethane dispersion can be provided.

In the aqueous polyurethane dispersion, the proportion of the structural unit (a1) derived from the polyol (a) in the molecular chain of the OH group-containing polyurethane may be 10% by mass or more and 60% by mass or less in terms of mass. By this feature, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

When they are assumed as a structural unit (A1), a structural unit (B1), a structural unit(C1) And all OH groups contained in all the polyols derived from the respective structural units (D1) are reacted with all the NCO groups contained in the diisocyanate derived from the structural unit (E1), and the total number of OH groups contained in the pseudo OH group-containing polyurethane molecule formed by the reaction is defined as f, the f is the average value of the f per 1000 calculated molecular weight of the pseudo OH group-containing polyurethane₁₀₀₀The value may be 2.1 or more and 2.9 or less. By this feature, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The acid value of the OH group-containing polyurethane may be 14 or more and 55 or less. By this feature, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The structural unit (E1) may further include a structural unit (E1b), and the structural unit (E1b) is derived from at least one diisocyanate selected from the group consisting of an aromatic diisocyanate compound other than xylylene diisocyanate (Ea), an alicyclic diisocyanate compound, and an aliphatic diisocyanate compound. This feature enables more reliable formation of a coating film having self-repairability and ultraviolet absorber resistance.

The polyol (a) may be a polycarbonate polyol mainly composed of at least one of 1, 6-hexanediol and 1, 4-cyclohexanedimethanol. The polyol (a) may be a polyester polyol mainly composed of a lactone. By this feature, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed. In the present specification, "mainly" means that the ratio is 50% by mass or more, preferably 75% by mass or more. For example, the component X mainly contains A, and 50 mass% or more of the substances constituting the component X are A. That is, 50% by mass or more of the polycarbonate polyol may be at least one of 1, 6-hexanediol and 1, 4-cyclohexanedimethanol. In addition, at least 50% by mass of the polyester polyol may be a lactone.

The structural unit derived from a polyvalent alcohol (C1) may be mainly composed of a structural unit composed of trimethylolpropane. By forming such a polyurethane aqueous dispersion, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The structural unit (B1) derived from the first diol may be mainly composed of a structural unit composed of 1, 4-cyclohexanedimethanol. By forming such a polyurethane aqueous dispersion, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The invention of the present application also relates to a process for producing the aqueous polyurethane dispersion. The production method of the present invention is a method for producing an aqueous polyurethane dispersion, comprising: a polyurethane synthesis step (1) for synthesizing an OH group-containing polyurethane having a weight-average molecular weight of 16000 or more and 140000 or less by reacting a polyol (A), a first diol (B), a polyvalent alcohol (C), a second diol (D), and a diisocyanate component (E); a neutralization step (2) for neutralizing the synthesized OH group-containing polyurethane with a neutralizing agent comprising a tertiary amine; and a production step (3) for dispersing the neutralized product formed in the neutralization step in water to produce an aqueous polyurethane dispersion in which the neutralized product is dispersed in water. By this method, an aqueous polyurethane dispersion capable of forming a coating film having self-repairability and ultraviolet absorber resistance can be provided.

In the polyurethane synthesis step (1), the proportion of the structural unit (a1) derived from the polyol (a) in the entire OH group-containing polyurethane synthesized in the polyurethane synthesis step (1) may be 10 mass% or more and 60 mass% or less in terms of mass ratio. As described above, by adjusting the proportion of the structural unit (a1), a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

In the polyurethane synthesis step (1), when it is assumed that all OH groups contained in all polyols that are the sources of the structural unit (a1), the structural unit (B1), the structural unit (C1) and the structural unit (D1) react with all NCO groups contained in diisocyanate that is the source of the structural unit (E1), and the total number of OH groups contained in a pseudo OH group-containing polyurethane molecule formed by the reaction is defined as a f value, the f value that is the average value of the f values per 1000 calculated molecular weights of the pseudo OH group-containing polyurethane is f₁₀₀₀The value may be 2.1 or more and 2.9 or less. By making adjustments so that f is above₁₀₀₀The reaction proceeds with the value within the above range, canThe coating film has excellent self-repairing property and ultraviolet absorber resistance.

In the polyurethane synthesis step (1), the reaction may be carried out so that the acid value of the OH group-containing polyurethane is 14 or more and 55 or less. By adjusting the acid value in this manner, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The diisocyanate component (E) may further contain, in addition to the xylylene diisocyanate (Ea), at least one diisocyanate (Eb) selected from the group consisting of aromatic diisocyanate compounds other than the xylylene diisocyanate (Ea), alicyclic diisocyanate compounds and aliphatic diisocyanate compounds. By further containing diisocyanate (Eb), an aqueous polyurethane dispersion capable of more reliably forming a coating film having self-repairability and ultraviolet absorber resistance can be provided more reliably.

The invention of the present application further relates to a water-based coating composition comprising the above aqueous polyurethane dispersion as a first dispersion; and at least one dispersion of a carbodiimide crosslinking agent aqueous dispersion and a polyisocyanate crosslinking agent dispersion as a second dispersion, the carbodiimide crosslinking agent aqueous dispersion containing a carbodiimide group of 150 equivalents or more and 600 equivalents or less as a nonvolatile component; the polyisocyanate crosslinking agent dispersion contains 5 to 25 mass% of isocyanate groups as nonvolatile components in terms of mass. By using such an aqueous coating composition, a coating film having self-repairability and ultraviolet absorber resistance can be formed.

The water-based coating composition may be a multi-liquid coating composition comprising a first liquid containing an aqueous polyurethane dispersion and a second liquid containing at least one dispersion of an aqueous dispersion of a carbodiimide crosslinking agent and a dispersion of a polyisocyanate crosslinking agent. By using such a multi-liquid type coating composition, coating can be performed more easily and reliably.

In the above-mentioned water-based coating composition, the equivalent ratio N ═ C ═ N/COOH of the carbodiimide group (N ═ C ═ N group) in the carbodiimide crosslinking agent contained in the aqueous dispersion of the carbodiimide crosslinking agent and the carboxyl group (COOH group) in the OH group-containing polyurethane contained in the aqueous dispersion of polyurethane may be 0.30 or more and 1.7 or less. By using such an aqueous coating composition, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

In the above-mentioned water-based coating composition, the equivalent ratio NCO/OH ratio of the isocyanate group (NCO) in the polyisocyanate crosslinking agent contained in the polyisocyanate crosslinking agent dispersion to the OH group in the OH group-containing polyurethane contained in the polyurethane water dispersion may be 0.30 or more and 2.5 or less. By using such an aqueous coating composition, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The present invention also relates to a coating film formed by applying the aqueous polyurethane dispersion or the aqueous coating composition to a substrate. The coating film has self-repairability and ultraviolet absorber resistance.

[ details of the embodiments of the invention of the present application ]

The following describes the embodiments of the present invention in detail. An aqueous polyurethane dispersion according to an embodiment of the present invention contains: water; and a neutralized product of polyurethane containing OH groups and tertiary amine dispersed in water, the polyurethane containing OH groups having OH groups at the molecular chain terminals. The OH group-containing polyurethane contains a structural unit (a1) derived from the polyol (a), a structural unit (B1) derived from the first diol (B), a structural unit (C1) derived from the polyvalent alcohol (C), a structural unit (D1) derived from the second diol (D), and a structural unit (E1) derived from the diisocyanate component (E) in the molecular chain. The polyol (A) is at least one of a polycarbonate polyol and a polyester polyol, and has a number average molecular weight of more than 500 and not more than 5000. The first diol (B) is a diol having a number average molecular weight of 500 or less and having no carboxyl group. The polyvalent alcohol (C) is a polyvalent alcohol having a number average molecular weight of 500 or less and a number of functional groups per molecule of more than 2 and 4 or less. The second diol (D) is a diol having a carboxyl group. The diisocyanate component (E) comprises xylylene diisocyanate (Ea). Further, the structural unit (E1) includes the structural unit (E1a) derived from xylylene diisocyanate (Ea). The weight average molecular weight of the OH group-containing polyurethane is 16000 or more and 140000 or less.

The aqueous polyurethane dispersion is a dispersion or emulsion obtained by dispersing a neutralized product obtained by neutralizing the above-mentioned polyurethane containing OH groups in water. By adopting such a configuration, the surface protective agent having self-repairability and ultraviolet absorber resistance and serving as a substrate and a case can be sufficiently exhibited.

The aqueous polyurethane dispersion according to an embodiment of the present invention is a so-called aqueous polyurethane dispersion. Therefore, the environmental load can be reduced as compared with an organic solvent-based polyurethane dispersion.

Next, the structure of the OH group-containing polyurethane will be described. The OH group-containing polyurethane is a neutralized product of OH group-containing polyurethane and tertiary amine. The OH group-containing polyurethane contains in the molecular chain: a structural unit (A1) derived from a polyol which is at least one of a polycarbonate polyol and a polyester polyol and has a number average molecular weight of more than 500 and not more than 5000; a structural unit (B1) derived from a first diol having a number average molecular weight of 500 or less and having no carboxyl group; a structural unit (C1) derived from a polyvalent alcohol having a number average molecular weight of 500 or less and a number of functional groups per molecule of more than 2 and 4 or less; a structural unit (D1) from a second diol having a carboxyl group; and a structural unit derived from a diisocyanate (E1).

[ structural Unit (A1) ]

The OH group-containing polyurethane contains a structural unit (A1) derived from the polyol (A) in the molecular chain. The polyol (a) is at least one of a polycarbonate polyol and a polyester polyol, and has a number average molecular weight of more than 500 and not more than 5000.

The structural unit (a1) is formed from a polyol (a) which is at least one of a polycarbonate polyol and a polyester polyol and has a number average molecular weight of more than 500 and not more than 5000. The structural unit derived from the polycarbonate polyol and the structural unit derived from the polyester polyol are formed by using the polycarbonate polyol having the number average molecular weight and the polyester polyol having the number average molecular weight as raw materials, respectively.

The polycarbonate polyol is obtained by subjecting a polyol compound and a carbonate compound to, for example, dealcoholization or dephenolization.

The polyol compound that can be used for the synthesis of the polycarbonate polyol is not particularly limited, and examples thereof include: ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, neopentyl glycol, 1, 8-octanediol, 1, 9-nonanediol, diethylene glycol, dipropylene glycol, 1, 4-cyclohexanedimethanol, an ethylene oxide adduct of bisphenol a, a propylene oxide adduct of bisphenol a, a diol such as sorbitol cyclo-diol, and a polyvalent alcohol such as trimethylolpropane, glycerol, and pentaerythritol. One kind of the polyhydric alcohol compound may be used alone, or two or more kinds may be used in combination. Among these, a polycarbonate polyol mainly composed of at least one of 1, 6-hexanediol and 1, 4-cyclohexanedimethanol is preferably used. By using one or both of 1, 4-cyclohexanedimethanol and 1, 6-hexanediol alone, an aqueous polyurethane dispersion which can form a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

Examples of the carbonate-based compound used for the synthesis of the polycarbonate polyol include: ethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and the like. The carbonate-based compound may be used alone or in combination of two or more.

The polyester polyol is obtained by copolymerization or polycondensation reaction of a carboxylic acid component with a diol and/or a polyvalent alcohol used for synthesis of the polycarbonate polyol. The polyester polyol may be mainly composed of lactone. In particular, by using a polyester polyol mainly containing lactone, a polyurethane aqueous dispersion capable of forming a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed.

The structural unit (a1) can be formed by copolymerization of, for example, a polyester polyol. The polyester polyol can be obtained by copolymerization of: for example, at least one of the diols and polyvalent alcohols described above as substances that can be used for the synthesis of the polycarbonate polyol; dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, isophthalic acid, sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, fumaric acid, citric acid, itaconic acid, glutamic acid, and 1, 4-cyclohexanedicarboxylic acid; or oils and fats such as castor oil.

The structural unit (a1) can also be formed by, for example, a polycondensation reaction of a lactone polyol. For example, the constituent unit (A1) can also be obtained by polycondensation reaction of a diol used for synthesis of a polycarbonate polyol and a lactone such as e-caprolactone, delta-valerolactone or 3-methyl-delta-valerolactone. Among them, epsilon-caprolactone is particularly preferably used.

The structural unit (A1) constituting the OH group-containing polyurethane is a unit constituting a molecular chain and is derived from a polyol (A) which is at least one of a polycarbonate polyol and a polyester polyol and has a number average molecular weight of more than 500 and not more than 5000. By setting the number average molecular weight as described above, a coating film having more excellent self-repairability and ultraviolet absorber resistance can be formed more reliably.

[ structural Unit (B1) ]

The OH group-containing polyurethane contains a structural unit (B1) derived from the first diol (B) in the molecular chain. The first diol (B) is a diol having a number average molecular weight of 500 or less and having no carboxyl group. That is, the structural unit (B1) is a structural unit that does not overlap with the structural unit (a 1).

Examples of the structural unit (B1) derived from the first diol include structural units derived from a diol (B) which has no carboxyl group and is described above as a compound of a polyol which can be used for the synthesis of a polycarbonate polyol. Among them, the diol (B) includes, in particular: 1, 4-butanediol, 1, 6-hexanediol, 1, 4-cyclohexanedimethanol, and the like. Among these, the structural unit derived from the first diol (B1) preferably mainly comprises a structural unit composed of 1, 4-cyclohexanedimethanol.

The diol (B) has a number average molecular weight of 500 or less. Thus, a coating film having excellent self-repairability and ultraviolet absorber resistance can be formed. In addition, sufficient hardness can be imparted to the coating film.

[ structural Unit (C1)

The OH group-containing polyurethane contains a structural unit (C1) derived from a polyvalent alcohol (C) in the molecular chain. The polyvalent alcohol (C) is a polyvalent alcohol having a number average molecular weight of 500 or less and a number of functional groups per molecule of more than 2 and 4 or less. That is, the structural unit (C1) is a structural unit that does not overlap with the structural unit (a1) and the structural unit (B1).

The polyvalent alcohol (C) is not particularly limited, and examples thereof include: trivalent alcohols such as glycerin and trimethylolpropane, tetravalent alcohols such as tetramethylolmethane (pentaerythritol) and diglycerin, PO and/or EO adducts of the trivalent alcohols and the tetravalent alcohols, castor oil, and the like. Among these, the structural unit derived from a polyvalent alcohol (C1) is preferably mainly composed of a structural unit composed of trimethylolpropane.

The number average molecular weight of the polyvalent alcohol compound (C) is 500 or less, and the number of functional groups per molecule exceeds 2 and is 4 or less. With this structure, a coating film having an improved crosslinking density and further excellent self-repairability and ultraviolet absorber resistance can be formed. In addition, the aqueous polyurethane dispersion can provide high transparency by improving the solubility.

[ structural Unit (D1) ]

The OH group-containing polyurethane contains a structural unit (D1) derived from a second diol (D) having a carboxyl group in the molecular chain. That is, the structural unit (D1) is a structural unit that does not overlap with the structural unit (B1) and the structural unit (C1).

The second diol (D) having a carboxyl group, which is a source of the structural unit (D1), is not particularly limited, and examples thereof include: dimethylolalkanoic acids such as 2, 2-dimethylolpropionic acid and 2, 2-dimethylolbutyric acid, N-dihydroxyethylglycine, N-dihydroxyethylalanine, 3, 4-dihydroxybutanesulfonic acid, 3, 6-dihydroxy-2-toluenesulfonic acid, polyether polyols containing acidic groups, polyester polyols containing acidic groups, and the like. Of the above, dimethylol alkanoic acids are preferred, and 2, 2-dimethylol propionic acid and 2, 2-dimethylol butyric acid are more preferred. These may be used alone or in combination of two or more.

[ structural Unit (E1) ]

The OH group-containing polyurethane contains a structural unit (E1) derived from a diisocyanate component (E) in the molecular chain. The diisocyanate component (E) comprises xylylene diisocyanate (Ea). Further, the structural unit (E1) includes the structural unit (E1a) derived from xylylene diisocyanate (Ea).

The structural unit (E1a) derived from xylylene diisocyanate (Ea) is formed by using xylylene diisocyanate (Ea) as a raw material. Xylylene diisocyanate (Ea) is one of aromatic diisocyanates. In the present invention, by having a structural unit (E1a) derived from xylylene diisocyanate (Ea), it is possible to provide an aqueous polyurethane dispersion which can form a coating film having further improved ultraviolet absorber resistance.

The structural unit (E1) derived from the diisocyanate may further include a structural unit (E1b) derived from a diisocyanate (Eb) which is at least one selected from the group consisting of an aromatic diisocyanate compound other than xylylene diisocyanate (Ea), an alicyclic diisocyanate compound and an aliphatic diisocyanate compound. The structural unit (E1b) is formed by using, as a raw material, at least one diisocyanate (Eb) selected from the group consisting of an aromatic diisocyanate compound other than xylylene diisocyanate (Ea), an alicyclic diisocyanate compound, and an aliphatic diisocyanate compound.

The aromatic cyclic diisocyanate is not particularly limited, and examples thereof include: diphenylmethane diisocyanate (MDI), 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, xylene-1, 4-diisocyanate, xylene-1, 3-diisocyanate, tetramethylxylylene diisocyanate, m-phenylene diisocyanate, o-phenylene diisocyanate, and the like.

The alicyclic diisocyanate is not particularly limited, and examples thereof include: isophorone diisocyanate, 1, 3-cyclopentane diisocyanate, 1, 3-cyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, cyclohexyl diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, dicyclohexylmethane diisocyanate, bis (4-isocyanatocyclohexyl) methane, 1, 3-diisocyanatomethylcyclohexane, 1, 4-diisocyanatomethylcyclohexane, norbornane diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethyl xylene diisocyanate and the like.

The aliphatic diisocyanate is not particularly limited, and examples thereof include: hexamethylene diisocyanate, tetramethylene diisocyanate, 1, 5-pentamethylene diisocyanate, trimethylhexamethylene diisocyanate, 2-methyl-pentane-1, 5-diisocyanate, 3-methyl-pentane-1, 5-diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate, lysine isocyanate, ethylene oxide diisocyanate, norbornene diisocyanate, and the like.

[ Tertiary amines ]

The aqueous polyurethane dispersion of the present embodiment contains a neutralized product of polyurethane containing an OH group and a tertiary amine dispersed in water. The tertiary amines can act as neutralizing agents for polyurethanes containing OH groups.

The above-mentioned tertiary amine compound used for neutralizing the OH group-containing polyurethane is not particularly limited, and there may be mentioned: trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, N-methyldiethanolamine, N-phenyldiethanolamine, dimethylethanolamine, diethylethanolamine, N-methylmorpholine, pyridine, and the like. Among them, dimethylethanolamine and triethylamine are preferable. These may be used alone or in combination of two or more.

[ aqueous polyurethane Dispersion ]

The aqueous polyurethane dispersion of the present embodiment contains: water; and a neutralized product of polyurethane containing OH groups and tertiary amine dispersed in water. The OH group-containing polyurethane has OH groups at the molecular chain terminals. The amount of the neutralized product, the amount of water as a dispersion medium and the ratio thereof are not particularly limited, and the amount and the ratio required for sufficiently dispersing the OH group-containing polyurethane may be appropriately selected.

[ OH group-containing polyurethane ]

As described above, the OH group-containing polyurethane contained in the aqueous polyurethane dispersion of the present embodiment includes the structural unit (a1), the structural unit (B1), the structural unit (C1), the structural unit (D1), and the structural unit (E1).

In the OH group-containing polyurethane, the proportion of the structural unit (a1) derived from the polyol in the molecular chain of the OH group-containing polyurethane is preferably 10 mass% or more and 60 mass% or less in terms of mass. Such a ratio can be achieved by setting the mass ratio of the polyol (a) of at least either one of the polycarbonate polyol and the polyester polyol, which is the source of the structural unit (a1), to 10 mass% or more and 60 mass% or less in the entire OH group-containing polyurethane. By setting the above ratio to 10% by mass or more and 60% by mass or less, it is possible to more reliably provide an aqueous polyurethane dispersion which can form a coating film exhibiting self-repairability and ultraviolet absorber resistance.

When it is assumed that all OH groups contained in all polyols from which the structural unit (a1), the structural unit (B1), the structural unit (C1) and the structural unit (D1) are derived react with all NCO groups contained in diisocyanate from which the structural unit (E1) is derived, and the total number of OH groups contained in a pseudo OH group-containing polyurethane molecule formed by the reaction is represented by f, it is preferable that f is an average value of f values per 1000 calculated molecular weights of the pseudo OH group-containing polyurethane₁₀₀₀The value is 2.1 or more and 2.9 or less.

The above f will be shown below₁₀₀₀An example of the method for solving the value of (c) is described (the method for solving (c) is not limited to this method).

First, the calculated molecular weight was calculated.

The total x coefficient n of the molecular weight ═ [ (molecular weight of each raw material) × (mol number of each raw material) ] was calculated

The coefficient n is obtained as follows. For example, it is assumed that an OH raw material reacts with an NCO raw material to form OH-terminated polyurethane. When the raw material has a valence of 2 or more, a polyol of [ (xmol) +1mol ] is inevitably synthesized with respect to the polyisocyanate (xmol). The coefficient n is thus determined.

The coefficient n is 1/{ (total of mol numbers of polyols) - (total of mol numbers of polyisocyanates) }

Subsequently, the f value is obtained. The value f represents the total number of OH groups contained in a virtual OH group-containing polyurethane molecule formed by the reaction of all OH groups contained in all polyols that are the sources of the structural unit (a1), the structural unit (B1), the structural unit (C1) and the structural unit (D1) with all NCO groups contained in diisocyanate that is the source of the structural unit (E1). The f-number is calculated as the average of the calculated molecular weights per unit.

The above f value is given by

Formula Mn (calculated molecular weight) 56.11/hydroxyl value x f x 1000

The value of f is derived as (Mn. times. hydroxyl value)/(56.11. times.1,000)

(56.11 is the molecular weight of potassium hydroxide).

Next, the average value f per 1000 calculated molecular weights was calculated₁₀₀₀。

f₁₀₀₀{ (f-2) × (1000/calculated molecular weight) } +2

That is, assuming that both terminals of the OH group-containing polyurethane molecule are OH groups, a part other than the OH groups at both terminals is cut out from the OH group-containing polyurethane, the cut-out part is linked to the OH groups at both terminals to prepare a molecular model having a calculated molecular weight of 1000, f₁₀₀₀The value is a standard for the average of the total number of OH groups of the OH-containing polyurethane in this case.

The average value f is shown below₁₀₀₀An example of the calculation method of (3).

When etrnacoll UC100 (polycarbonate diol) (manufactured by yunnan corporation) 0.46(mol) × 1,000(Mn) ═ 460 as component (a), 1,4-CHD (1, 4-cyclohexanedimethanol) (manufactured by eastman chemical company) 2.3(mol) × 144(Mn) × 331.2 as component (B), TMP (trimethylolpropane) (manufactured by aifeny japan) 0.4(mol) × 134(Mn) ═ 53.6 as component (C), DMPA (dimethylolpropionic acid) (manufactured by permtop corporation) 1.0(mol) × 134 as component (D), Takenate500 (xylylene diisocyanate) (manufactured by mitsui chemical corporation) 2.0(mol) × 376.4 as component (188.0 (mol) × 376.4) and HDI (hexamethylene diisocyanate) (manufactured by eastern chemical company) 2.168 (egia) × 2.38) (eesoga) (336.4),

the total of [ (molecular weight of each raw material) × (mol number of each raw material) ] is 1691.6

The coefficient n is 1/{ (a) (mol) + (B) (mol) + (C) (mol) + (D) (mol) - (Ea) (mol) - (Eb) (mol) } 1/0.16 is 6.25

Calculated molecular weight 1691.6 × 6.25-10572.5

Hydroxyl value 56.11X 0.72X 1000/1691.6 23.88

f value is 4.50

Average f value of f values per 1,000 calculated molecular weights₁₀₀₀＝2.24。

In the present embodiment, it is preferable that the acid value of the OH group-containing polyurethane is 14 or more and 55 or less. By adjusting the acid value to the above range, the OH group-containing polyurethane can be more reliably synthesized.

The weight average molecular weight of the OH group-containing polyurethane is 16000 or more and 140000 or less. By adopting the above-specified range, excellent adhesion can be obtained by improving the glossiness and the wettability to the base material such as plastic. By forming a coating film using a polyurethane aqueous dispersion composed of the OH group-containing polyurethane composition and an aqueous composition containing the polyurethane aqueous dispersion, a coating film having excellent self-repairability and durability against an ultraviolet absorber contained in cosmetics, sunscreen agents, and the like can be obtained.

As such a polyurethane aqueous dispersion, a polyurethane aqueous dispersion which can reduce environmental load and can form a coating film having self-repairability and ultraviolet absorber resistance can be obtained. Further, according to the aqueous polyurethane dispersion of the present embodiment, a coating film excellent in appearance and adhesion to a substrate can be formed.

[ Water-based coating composition ]

Next, the structure of the aqueous coating composition according to one embodiment of the present invention will be described. The aqueous coating composition of the present embodiment comprises the above-mentioned polyurethane aqueous dispersion as a first dispersion, and at least one dispersion of a carbodiimide cross-linking agent aqueous dispersion and a polyisocyanate cross-linking agent aqueous dispersion as a second dispersion, the carbodiimide cross-linking agent aqueous dispersion containing a carbodiimide group of 150 equivalents or more and 600 equivalents or less as a nonvolatile component; the polyisocyanate crosslinking agent dispersion contains 5 to 25 mass% of isocyanate groups as nonvolatile components in terms of mass. By using such an aqueous coating composition, a multi-liquid coating composition capable of forming a coating film having self-repairability and ultraviolet absorber resistance can be provided.

The aqueous coating composition of the present embodiment can also be a multi-liquid coating composition containing a first liquid containing the aqueous polyurethane dispersion and a second liquid containing at least one dispersion of an aqueous dispersion of a carbodiimide crosslinking agent and a dispersion of a polyisocyanate crosslinking agent. By making such a multi-liquid type coating composition, coating can be performed more easily and reliably.

The second liquid may contain a liquid containing a carbodiimide dispersion, and the equivalent ratio N ═ C ═ N/COOH of the content of carbodiimide groups (N ═ C ═ N groups) in the carbodiimide dispersion to the carboxyl groups (COOH groups) in the aqueous polyurethane dispersion may be 0.30 or more and 1.7 or less. The water-based coating composition can form a coating film having more excellent self-repairability and ultraviolet absorber resistance.

The second liquid may contain a liquid containing a polyisocyanate dispersion, and the equivalent ratio NCO/OH ratio of the content of isocyanate groups (NCO) in the liquid containing a polyisocyanate dispersion to OH groups (OH groups) in the aqueous polyurethane dispersion may be 0.30 or more and 2.5 or less. The water-based coating composition can form a coating film having more excellent self-repairability and ultraviolet absorber resistance.

[ Process for producing aqueous polyurethane Dispersion ]

Next, a method for producing an aqueous polyurethane dispersion according to an embodiment of the present invention will be described. The method for producing the aqueous polyurethane dispersion of the present embodiment includes a polyurethane synthesis step (1), a neutralization step (2), and a production step (3). Fig. 1 is a flow chart showing a typical process of a method for producing an aqueous polyurethane dispersion according to an embodiment of the present invention.

Referring to fig. 1, first, as a preparation step, the first glycol and the like described above are prepared (S11). That is, a polyol (a) which is at least one of a polycarbonate polyol and a polyester polyol and has a number average molecular weight of more than 500 and not more than 5000, a first diol (B), a polyvalent alcohol (C), a second diol (D), and a diisocyanate component (E) are prepared; the first diol (B) has a number average molecular weight of 500 or less and has no carboxyl group; the number average molecular weight of the polyvalent alcohol (C) is 500 or less and the number of functional groups per molecule exceeds 2 and is 4 or less; the second diol (D) has a carboxyl group; the diisocyanate component (E) comprises xylylene diisocyanate (Ea).

Next, a polyurethane synthesis step (1) of synthesizing OH group-containing polyurethane is performed (S12). In the polyurethane synthesis step (1), the polyol (a), the first diol (B), the polyvalent alcohol (C), the second diol (D), and the diisocyanate component (E) are reacted to synthesize OH group-containing polyurethane having OH groups at the molecular chain terminals. In the polyurethane synthesis step (1), an OH group-containing polyurethane having a weight average molecular weight of 16000 or more and 140000 or less is synthesized. The above reaction may be carried out so that the proportion of the structural unit (a1) derived from the polyol (a) in the entire OH group-containing polyurethane synthesized is 10 mass% or more and 60 mass% or less in terms of mass ratio, or so that the acid value of the OH group-containing polyurethane becomes 14 or more and 55 or less. In this step, the diisocyanate component (E) and the other polyol components (a) to (D) are reacted separately. The order of the reaction is not particularly limited, and for example, the reaction can be carried out in stages, that is, first, the component (A) and the component (E) are reacted, and then, the component (B), the component (C) and the component (D) are added to carry out chain extension, thereby synthesizing the desired OH group-containing polyurethane.

The above-mentioned OH group-containing polyurethane can be synthesized in a solvent. The solvent is not particularly limited as long as it is a hydrophilic solvent that does not substantially react with an isocyanate group. For example, there may be mentioned: ketones such as acetone and ethyl methyl ketone, esters, ethers such as tetrahydrofuran and N-methylmorpholine, and amides such as 3-methoxy-N, N-dimethylpropane amide, dimethylformamide, N-methylpyrrolidone and N-ethylpyrrolidone. These may be used alone or in combination of two or more.

The amount of the solvent to be added is not particularly limited, but is preferably 10 to 150% by mass based on 100 parts by mass of the solid content of the OH group-containing polyurethane.

In addition, the reaction can be carried out in the presence of a catalyst. The kind of the catalyst is not particularly limited, and for example, there may be mentioned: tin-based catalysts (e.g., trimethyltin laurate and dibutyltin dilaurate), Li-based catalysts, metal catalysts such as Bi-based catalysts, amine-based catalysts (e.g., triethylamine, N-ethylmorpholine, and triethyldiamine), and diazabicycloundecene-based catalysts. Among them, from the viewpoint of reactivity and reduction of environmental load, it is preferable to use a Li-based/Bi-based metal catalyst in combination.

Subsequently, a neutralization step (2) of neutralizing the synthesized OH group-containing polyurethane with a neutralizing agent composed of a tertiary amine is performed to form a neutralized product (S13). The OH group-containing polyurethane synthesized in the polyurethane synthesis step (1) is neutralized with a tertiary amine, more specifically, COOH groups (carboxyl groups) contained in the OH group-containing polyurethane are neutralized. The amount of the tertiary amine to be added is appropriately determined in consideration of the amount of COOH groups contained in the OH group-containing polyurethane before neutralization.

Next, an aqueous polyurethane dispersion in which the neutralized product neutralized in the neutralization step (2) is dispersed in water is prepared (S14). The method for producing such an aqueous polyurethane dispersion is not particularly limited, and for example, an aqueous polyurethane dispersion can be produced by charging a container with water, and dispersing the neutralized product obtained in steps S11 to S13 in water using a stirrer, a homogenizer, or the like. Further, the dispersion is not limited to the case of obtaining a neutralized product and then dispersing it in water, and it is also possible to disperse the OH group-containing polyurethane while neutralizing it. Therefore, the steps S13 and S14 may not be completely separated, but at least a part of the steps may be shared. For example, it is also possible to prepare an aqueous polyurethane dispersion by phase inversion emulsification or forced emulsification of an OH group-containing polyurethane using water to which a tertiary amine is added.

When in polyurethane synthesisIn the OH group-containing polyurethane synthesized in the step (1), assuming that all OH groups contained in all the polyols from which the structural unit (A1), the structural unit (B1), the structural unit (C1) and the structural unit (D1) are derived react with all NCO groups contained in the diisocyanate from which the structural unit (E1) is derived, and the total number of OH groups contained in the virtual OH group-containing polyurethane molecule formed by the reaction is set to f, the f value, which is the average value of the f values per 1000 calculated molecular weights of the virtual OH group-containing polyurethane, is f value₁₀₀₀The value may be 2.1 or more and 2.9 or less.

According to the method for producing a polyurethane aqueous dispersion, a polyurethane aqueous dispersion which can reduce environmental load and can form a coating film having self-repairability and ultraviolet absorber resistance can be easily produced. Further, the coating film obtained from the aqueous polyurethane dispersion formed by the method for producing an aqueous polyurethane dispersion according to the present embodiment is also excellent in appearance and adhesion to a substrate.

[ coating film ]

A coating film can be formed from the aqueous polyurethane dispersion or the aqueous coating composition. A coating film is formed by applying an aqueous polyurethane dispersion or an aqueous coating composition to a predetermined substrate, and drying and curing the composition as necessary. The coating film has self-repairability and ultraviolet absorber resistance.

[ use ]

The aqueous polyurethane dispersion or the water-based coating composition can be used as a surface protective material for various substrates. For example, the aqueous polyurethane dispersion or the aqueous coating composition is applied to a substrate to form a coating film for protecting the surface of interior materials of vehicles, audio equipment, personal computers, cellular phones, and the like, and thus can be used as a surface protective material having self-repairability and ultraviolet absorber resistance.