JP7487524B2 - Water-based acrylic-urethane compositions for fracture-resistant materials - Google Patents

Description

The present invention relates to an aqueous acrylic-urethane composition obtained by mixing an aqueous polyurethane resin dispersion in which a polyurethane resin is dispersed in an aqueous medium with an acrylic emulsion. The present invention also relates to a coating material composition containing the aqueous acrylic-urethane composition, and an acrylic-urethane resin film obtained by heating and drying the aqueous acrylic-urethane composition.

Aqueous polyurethane resin dispersions can be used to obtain coating films that have adhesiveness, abrasion resistance, and rubber-like properties, and they also contain less volatile organic compounds than conventional solvent-based polyurethanes, making them an environmentally friendly material that is increasingly replacing solvent-based polyurethanes.
Polycarbonate polyol is a useful compound that can be used as a raw material for producing durable polyurethane resins used in rigid foams, flexible foams, paints, adhesives, synthetic leather, ink binders, etc., by reacting with an isocyanate compound. It is described that polyurethanes using polycarbonate polyols are characterized by the high cohesive force of carbonate groups, and are excellent in water resistance, heat resistance, oil resistance, elastic recovery, abrasion resistance, and weather resistance (see Non-Patent Document 1). It is also known that coating films obtained by applying aqueous urethane resin dispersions using polycarbonate polyols as raw materials are excellent in light resistance, heat resistance, hydrolysis resistance, and oil resistance (see Patent Document 1).

As mentioned above, aqueous polyurethane resin dispersions using polycarbonate polyols exhibit good properties, but they are not sufficient compared to solvent-based polyurethanes. In particular, the solvent resistance and water resistance of the coating film are insufficient. In order to improve such properties, crosslinking structures are introduced into polyurethane resins, or crosslinking agents such as epoxy resins and polyfunctional isocyanates are introduced into the compositions to crosslink them during curing. Among these, aqueous polyurethane resin dispersions having blocked isocyanato groups are stable at room temperature, and therefore highly useful as one-liquid crosslinkable reactive dispersions with high storage stability (see, for example, Patent Documents 2 and 3).

Furthermore, the present inventors have discovered that an aqueous polyurethane resin dispersion having urethane bonds, urea bonds, and carbonate bonds and a specific amount of blocked isocyanato groups can control the film formation rate after coating and enable the coating film to be redispersed in water, and that the coating film obtained by coating and heating this has excellent water resistance and solvent resistance, excellent adhesion to electrodeposition coating films, and high breaking energy in tension, resulting in excellent impact resistance (see, for example, Patent Document 5).

It has also been found that an aqueous resin dispersion composition obtained by dispersing a polyurethane resin having a polymerizable unsaturated bond, a compound having a polymerizable unsaturated bond, and a carbodiimide compound and/or an oxazoline compound in an aqueous medium can provide a coating film that has excellent adhesion and high hardness after curing by irradiation with active energy rays (see, for example, Patent Document 6).

Japanese Patent Application Laid-Open No. 10-120757 JP 2002-128851 A JP 2000-104015 A JP 2005-220255 A International Publication No. 2010/098316 JP 2014-065886 A

"Latest Polyurethane Materials and Application Technology" CMC Publishing, Chapter 2, page 43

From the perspective of greenhouse gas emissions and the heat resistance temperature when painting multiple substrates at once, it is necessary to create a coating by lowering the drying temperature from the conventional 140°C or higher to 100°C or lower, but the use of blocked isocyanates, which require heating to high temperatures, is becoming difficult.
Therefore, there has been a demand for a material that satisfies both the impact resistance (breaking energy) and adhesion requirements without using a crosslinking reaction.

When the aqueous polyurethane resin dispersion is used as a film, paint or coating material, it is applied to a substrate or the like using an application device such as a bar coater, a roll coater, or an air spray. The applied aqueous polyurethane resin dispersion is heated and dried to form a coating film on the substrate. However, in the case of conventional aqueous polyurethane resin dispersions, a drying process at 140° C. or higher is required to obtain sufficient adhesion to the substrate and large breaking energy in tension. A drying process at 100° C. or lower, for example 80° C., has a problem that the coating film does not adhere to the substrate.
Furthermore, in Patent Document 6, ultraviolet irradiation is required, and as the polymer having two or more oxazoline structures, only a polymer obtained by homopolymerizing an oxazoline group-containing ethylenically unsaturated monomer using a known polymerization method, or a polymer obtained by copolymerizing an oxazoline group-containing ethylenically unsaturated monomer with another vinyl monomer is mentioned.

The object of the present invention is to provide an aqueous polyurethane resin dispersion for fracture-resistant materials that forms a coating film with high breaking energy while maintaining adhesion to the substrate when dried at low temperatures of 100°C or less.

The inventors discovered that a coating film formed by drying at a low temperature of 100°C or less using an aqueous acrylic-urethane composition containing an aqueous polyurethane resin dispersion and an oxazoline crosslinked acrylic emulsion can have high adhesion to the substrate and high breaking energy, leading to the present invention.

Specifically, the present invention is as follows.
(1) The first invention is an aqueous acrylic-urethane composition for a fracture-resistant material, comprising an aqueous polyurethane resin dispersion (A) and an oxazoline crosslinked acrylic emulsion (B). The aqueous polyurethane resin dispersion (A) has structural units derived from a polyol compound (Aa), a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), a neutralizing agent (Ad) and a chain extender (Ae). The oxazoline crosslinked acrylic emulsion (B) is an aqueous acrylic-urethane composition, comprising a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc).
(2) A second invention is the aqueous acrylic-urethane composition for fracture-resistant materials according to the above (1), wherein the oxazoline group contained in the oxazoline crosslinking acrylic emulsion (B) is at least one selected from the group consisting of a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group.
(3) The third invention is the aqueous acrylic-urethane composition for fracture-resistant materials according to the above (1) or (2), wherein the weight-average molecular weight of the oxazoline crosslinked acrylic emulsion (B) is 100,000 or more.
(4) A fourth invention is the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of (1) to (3) above, wherein the acrylic skeleton in the oxazoline crosslinking acrylic emulsion (B) has at least one component selected from an acrylic acid ester and/or a methacrylic acid ester having a hydrocarbon group having 1 to 20 carbon atoms as a constituent unit thereof.
(5) A fifth invention is the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of (1) to (4), wherein the content of the oxazoline crosslinked acrylic emulsion (B) is 2 to 80 mass % on a solids basis with respect to the total amount of the composition.
(6) A sixth invention is the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of (1) to (5) above, wherein the amount of oxazoline groups contained in the oxazoline crosslinking acrylic emulsion (B) is 0.0002 to 0.4 mmol/g based on the solid content with respect to the total amount of the emulsion.
(7) A seventh invention is the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of (1) to (6), wherein the polyol compound (Aa) of the aqueous polyurethane resin dispersion contains a polycarbonate polyol having a number average molecular weight of 400 to 5,000.
(8) An eighth invention is the aqueous acrylic-urethane composition for fracture-resistant materials according to the above (7), wherein the polycarbonate polyol has a glass transition temperature of -60°C to 0°C.
(9) The ninth invention is the aqueous acrylic-urethane composition for fracture-resistant materials according to the above (7) or (8), wherein the polyol constituting the polycarbonate polyol is selected from 1,6-hexanediol and/or 1,4-cyclohexanedimethanol.
(10) A tenth aspect of the present invention is the aqueous acrylic urethane composition for a fracture-resistant material according to any one of (7) to (9), wherein the aqueous polyurethane resin dispersion (A) contains an alicyclic structure, and the content of the alicyclic structure is 10 to 60% by weight based on the solid content of the aqueous polyurethane resin dispersion (A).
(11) An eleventh invention is the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of (1) to (10), wherein the polyisocyanate compound (Ab) of the aqueous polyurethane resin dispersion (A) is an alicyclic polyisocyanate.
(12) A twelfth aspect of the present invention is the aqueous acrylic urethane composition for a fracture-resistant material according to any one of (1) to (11) above, wherein the aqueous polyurethane resin dispersion (A) has an acid value of 12 to 40 mgKOH/g.
(13) A thirteenth invention is the aqueous acrylic urethane composition for a fracture-resistant material according to any one of (1) to (12) above, wherein the content of the hard segment in the aqueous polyurethane resin dispersion (A) is 20 to 65 mass% based on the solid content.
(14) The fourteenth invention is a coating material composition for destruction-resistant materials, comprising the aqueous acrylic-urethane composition for destruction-resistant materials described in (1) to (13) above, and other resins and/or additives as optional components.
(15) The fifteenth invention is an aqueous acrylic-urethane composition for a destruction-resistant material according to any one of (1) to (13) above, for use as a coating for plastic materials, or as a primer or base coat for exterior use on metals.
(16) A sixteenth invention is a coating film obtained by drying the aqueous acrylic-urethane composition for a destruction-resistant material according to any one of (1) to (13) above.
(17) A seventeenth aspect of the present invention is a method for producing a coating film, comprising a step of drying the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of (1) to (13) above at 20°C to 100°C.
(18) The eighteenth invention relates to the use of the coating film obtained by the method according to (17) above as a floor coat, a coat for plastics or rubber, a steel plate treatment agent, or a primer or base coat for metal exteriors.
(19) A nineteenth aspect of the present invention relates to a process for producing a polyurethane prepolymer, comprising: (I) reacting a polyol compound (Aa), a polyisocyanate compound (Ab), and an acidic group-containing polyol (Ac) in the presence or absence of an organic solvent;
(II) neutralizing the acid groups of the polyurethane prepolymer with a neutralizing agent (Ad);
(III) dispersing the polyurethane prepolymer in an aqueous medium;
(IV) a step of increasing the molecular weight of the polyurethane prepolymer with a chain extender (Ae) to obtain an aqueous polyurethane resin dispersion;
(V) a step of mixing a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc) to obtain an oxazoline crosslinked acrylic emulsion (B) with the aqueous polyurethane resin dispersion obtained in the step (IV); and optionally,
(VI) A method for producing an aqueous acrylic-urethane composition for use in a fracture-resistant material, comprising the step of removing the organic solvent following the step (IV) or (V).
(20) A twentieth invention is a composition comprising: an aqueous polyurethane resin dispersion (A) having structural units derived from a polyol compound (Aa), a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), a neutralizing agent (Ad) and a chain extender (Ae); and an oxazoline crosslinked acrylic emulsion (B) having a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc); wherein the aqueous acrylic urethane composition forms a coating film at a low temperature of 20°C to 100°C, and has a breaking energy of 80 MPa or more, calculated using tensile properties measured using an aqueous acrylic urethane according to a method in accordance with JIS K 7311 at a measurement temperature of 23°C, a humidity of 50%, and a tensile speed of 100 mm/min, and wherein no peeling is observed in four tries in the cross-cut peel test of the coating film on an ABS resin substrate.

According to the present invention, it is possible to provide an aqueous acrylic-urethane composition for fracture-resistant materials, in which the coating film formed by drying at room temperature (20°C) to 100°C, for example 80°C, has good adhesion to substrates such as plastic substrates and electrocoated coatings, and has high breaking energy. Therefore, compared to conventional high-temperature heating and drying, it can contribute to the suppression of greenhouse gas emissions and the reduction of the number of processes by integrally painting multiple substrates. The present invention can be used for floor coatings, coatings for plastic substrates or rubber, steel plate treatment agents, exterior primers (base coat materials) for vehicles such as automobiles, trucks, and trains, etc.

The aqueous acrylic urethane composition for a fracture-resistant material of the present invention is a composition for a fracture-resistant material comprising an aqueous polyurethane resin dispersion and an oxazoline crosslinking acrylic emulsion,
The aqueous polyurethane resin dispersion has structural units derived from a polyol compound (Aa), a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), a neutralizing agent (Ad), and a chain extender (Ae),
The oxazoline crosslinked acrylic emulsion (B) is an aqueous acrylic-urethane composition, which is an acrylic emulsion having a polymer (Ba) having an acrylic skeleton in its main chain and a functional group that reacts with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc).

<Oxazoline Crosslinked Acrylic Emulsion (B)>
The oxazoline crosslinked acrylic emulsion (B) is an acrylic emulsion comprising a polymer (Ba) having an acrylic skeleton in its main chain and a functional group in its side chain that reacts with an oxazoline group, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc). The acrylic emulsion forms a crosslinked structure in the process of removing water when the coating film dries.

The weight average molecular weight of the oxazoline crosslinked acrylic emulsion (B) is preferably 100,000 or more. There is no particular upper limit to the weight average molecular weight as long as it is within a range that can be prepared and dispersed in water, but the weight average molecular weight range is preferably 100,000 to 2,000,000, and more preferably 150,000 to 1,000,000.

The content of the oxazoline crosslinked acrylic emulsion (B) is preferably 2 to 80 mass % on a solids basis, more preferably 5 to 70 mass %, and even more preferably 10 to 60 mass %, based on the total amount of the composition for fracture-resistant materials. By setting the content of the oxazoline crosslinked acrylic emulsion (B) within the above range, adhesion to the substrate can be further improved and the fracture energy of the coating film can be further increased, which is preferable.

The amount of the oxazoline compound used is preferably 10% by weight or less, more preferably 0.01 to 3% by weight, and even more preferably 0.03 to 2.2% by weight, relative to the total solid content of the acrylic emulsion. By using an amount of 10% by weight or less, harmful formaldehyde generated by heating can be reduced, and the composition of the present invention, which includes a drying process in the production of a coating film, does not substantially contain or generate harmful substances such as formaldehyde, making it more preferable as an environmentally friendly material.
The amount of the oxazoline compound used is preferably within the above range, but it is more preferable to adjust the amount used so that the amount of oxazoline groups contained in the oxazoline crosslinked acrylic emulsion (B) is 0.0002 to 0.4 mmol/g based on the solid content relative to the total amount of the acrylic emulsion. The amount of oxazoline groups is more preferably in the range of 0.0005 to 0.3 mmol/g. The amount of oxazoline groups contained in the acrylic emulsion can be identified using a means known to those skilled in the art, such as NMR measurement.

<Polymer (Ba) Having an Acrylic Skeleton in the Main Chain and a Functional Group Reactive with an Oxazoline Group in the Side Chain>
The polymer (Ba) having an acrylic skeleton in the main chain and a functional group reactive with an oxazoline group in the side chain used in the present invention (hereinafter, sometimes simply referred to as "polymer (Ba)") is not particularly limited as long as it is mainly composed of an acrylic acid ester and/or a methacrylic acid ester. In this specification, a polymer "having an acrylic skeleton in the main chain" is used to indicate a polymer or copolymer mainly composed of an acrylic acid ester and/or a methacrylic acid ester. "Mainly composed" in a polymer means that the component is contained as a constituent element of the polymer in a proportion of 50% by weight or more. It is preferable that the polymer (Ba) has at least one component selected from an acrylic acid ester and/or a methacrylic acid ester having a hydrocarbon group having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, in its constituent units. Specific examples of acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, i-nonyl acrylate, tridecyl acrylate, stearyl acrylate, oleyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Specific examples of methacrylic acid esters include those in which the acrylic group portion of the above acrylates is replaced with a methacrylic group. A preferred specific example of the acrylic polymer is one that contains ethyl acrylate, and a more preferred specific example is one that contains ethyl acrylate and an α,β-unsaturated mono- or di-carboxylic acid having 3 to 5 carbon atoms as essential monomer components and is formed by emulsion copolymerization of these.
Examples of the functional group which reacts with an oxazoline group include an epoxy group, an amide group or a substituted amide group, a hydroxyl group, a carboxyl group, an amino group or a substituted amino group, and the like.

The polymer having an acrylic skeleton in the main chain used in the present invention (hereinafter, sometimes referred to as an acrylic polymer) may be crosslinked within the particle. The intra-particle crosslinking here refers to a state in which at least a part of the acrylic copolymer in the fine particles is crosslinked and insoluble or poorly soluble in water or solvents when the fine particles of the acrylic polymer are formed by emulsion copolymerization. Such intra-particle crosslinking may be due to an unsaturated monomer having multiple unsaturated bonds such as a vinyl group, an allyl group, or a (meth)acrylic group, but is preferably due to a monomer having a methylolamide group or a substituted methylolamide group, a carbonyl group, an amide group or a substituted amide group (excluding a methylolamide group or a substituted methylolamide group), an amino group or a substituted amino group, a hydroxyl group, a lower alkoxyl group, an epoxy group, a mercapto group, or a silicon-containing group, and is preferably due to the oxazoline group.

<Water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton and an oxazoline group in the main chain>
The water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in the main chain and an oxazoline group (hereinafter, sometimes simply referred to as "polymer (Bb)") is a polymer compound obtained by (co)polymerizing a monomer having an oxazoline group and, optionally, at least one other monomer copolymerizable therewith, in which at least one of the monomers can constitute an acrylic skeleton. It is preferable that the polymer compound is water-soluble or water-dispersible, since it is easily blended with the aqueous dispersion of the polymer (Ba).
The oxazoline group is at least one selected from the group consisting of a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group, and is preferably a 2-oxazoline group. The oxazoline group may have one or more other substituents bonded to the oxazoline ring, such as a halogen, a lower alkyl group, a cycloalkyl group, or an aryl group.

In a water-soluble or water-dispersible polymer having an oxazoline group, the oxazoline group may react with functional groups such as carboxyl groups and hydroxyl groups contained in the aqueous polyurethane resin dispersion (A) and the oxazoline crosslinked acrylic emulsion (B) at a relatively low temperature. Therefore, by using a water-soluble or water-dispersible polymer having an oxazoline group, the oxazoline group can react with these functional groups, resulting in strong adhesion.

The polymer (Bb) has an acrylic skeleton in the main chain, and preferably has at least one component selected from an acrylic acid ester and/or a methacrylic acid ester having a hydrocarbon group having 1 to 20 carbon atoms in its constituent units. Examples of the hydrocarbon group having 1 to 20 carbon atoms include a substituent having an aromatic ring or an alicyclic structure having 1 to 10 carbon atoms in the side chain of an alkyl group having 1 to 10 carbon atoms. Specific examples of the acrylic acid ester and the methacrylic acid ester are as described above. In addition to the acrylic skeleton, the polymer may have a skeleton derived from another monomer, such as a vinyl skeleton, an acrylamide skeleton, or a styrene skeleton. Therefore, the monomers that are the elements that constitute the polymer (Bb) are not particularly limited in type and number as long as they contain the elements that constitute the acrylic skeleton, that is, the acrylic acid ester and/or the methacrylic acid ester. The acrylic acid ester and/or the methacrylic acid ester as the monomer may have an oxazoline group, and a monomer other than the acrylic acid ester and/or the methacrylic acid ester may be a monomer having an oxazoline group.

The polymer (Bb) may have other functional groups, such as polyoxyalkylene groups, vinyl groups, allyl groups, alkenyl groups, (meth)acryloyl groups, and alkenyloxy groups, in addition to the oxazoline group. These skeletons may be derived from any of the monomers constituting the polymer (Bb).

The number average molecular weight of the polymer (Bb) is preferably 5,000 or more, more preferably 10,000 or more, and usually 1,000,000 or less. If the number average molecular weight is lower than 5,000, adhesion may not be improved. If the number average molecular weight is higher than 1,000,000, workability may be poor. In addition, the oxazoline value of the polymer (Bb) is preferably, for example, 1,500 g solid/eq. or less, more preferably 1,200 g solid/eq. or less. If the oxazoline value is higher than 1,500 g solid/eq., the amount of oxazoline groups contained in the molecule is small, and adhesion may not be improved.

Specific examples of the water-soluble or water-dispersible polymer (Bb) having an oxazoline group include oxazoline group-containing acrylic polymers such as EPOCROS WS-300, EPOCROS WS-500, and EPOCROS WS-700 manufactured by Nippon Shokubai Co., Ltd., and oxazoline group-containing acrylic/styrene polymers such as EPOCROS K-1000 series and EPOCROS K-2000 series manufactured by Nippon Shokubai Co., Ltd., and these may be used alone or in combination of two or more.
<Aqueous medium (Bc)>
Examples of the aqueous medium include water such as tap water, ion-exchanged water, distilled water, and ultrapure water, and mixed media of water and a hydrophilic organic solvent.
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 represented by "KJCMPA(R)-100" manufactured by KJ Chemical Co.; and hydroxyl group-containing tertiary amines such as 2-(dimethylamino)-2-methyl-1-propanol (DMAP). As the aqueous medium (Bc) used in the oxazoline crosslinked acrylic emulsion (B), it is preferable to use one containing water as the main component, and the content of the hydrophilic organic solvent in the aqueous medium is usually 20% by mass or less, preferably 10% by mass or less.

<Aqueous Polyurethane Resin Dispersion (A)>
The aqueous polyurethane resin dispersion used in the composition of the present invention has structural units derived from the polyol compound (Aa), the polyisocyanate compound (Ab), the acidic group-containing polyol (Ac), the neutralizing agent (Ad), and the chain extender (Ae).

<Polyol compound (Aa)>
The polyol compound (Aa) used in the present invention can be any polyol compound that can be used in the production of polyurethane resin. The polyol compound preferably contains a polycarbonate polyol (Aa1) from the viewpoint of adhesion to the substrate. In particular, from the viewpoint of adhesion to the substrate under low-temperature drying at 100°C or less, the polyol compound (Aa) preferably contains a polycarbonate polyol compound (Aa1) having a glass transition temperature of -60°C to 0°C or a number average molecular weight of 400 to 5000. In addition, other polyol compounds (Aa2) may be contained as optional components.

The polyol compound (Aa) contains a polycarbonate polyol (Aa1) having a glass transition temperature of -60°C to 0°C or a number average molecular weight of 400 to 5000, in an amount of preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more, based on the total amount of the polyol compound (Aa). There is no particular upper limit on the content of the polycarbonate polyol compound (Aa1), and it may account for the total amount of the polyol compound (Aa), i.e., 100% by mass.

<Polycarbonate polyol compound (Aa1)>
From the viewpoints of adhesion to a substrate and breaking energy, the polycarbonate polyol compound (Aa1) preferably has a glass transition temperature of −60° C. to 0° C., more preferably −57° C. to −10° C., and even more preferably −55° C. to −15° C. The glass transition temperature can be measured by a differential scanning calorimeter. A specific measurement method is described below.

The polycarbonate polyol compound (Aa1) is obtained by reacting one or more polyol components with a carbonate ester or phosgene. From the viewpoints of safety and handling of reagents, etc., it is easy to produce, and there is no by-production of terminal chlorinated products. Therefore, polycarbonate polyols obtained by reacting one or more polyol monomers with a carbonate ester are preferred.

As the polyol component of the polycarbonate polyol compound (Aa1), known polyols can be used. 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, and trimethylol. Polyhydric alcohols having three or more functional groups, such as propane and pentaerythritol; diols having an alicyclic structure in the main chain, such as 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, and 1,4-bis(hydroxyethoxy)cyclohexane. Examples of suitable polyols include aromatic diols such as 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol, 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. Alicyclic polyols and/or aliphatic polyols are preferred, and polyols containing an alicyclic structure (for example, an alicyclic polyol or a combination of an alicyclic polyol and an aliphatic polyol) and/or polyols composed of diols having 6 or less carbon atoms are more preferred, and polyols having a cyclohexane ring and/or 1,6-hexanediol are even more preferred. Particularly preferred polyols are 1,4-cyclohexanedimethanol and/or 1,6-hexanediol.

The polyol components of the polycarbonate polyol compound (Aa1) may be used alone or in combination. The type of polyol component can be appropriately adjusted depending on the physical properties required for the composition.

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 particularly preferred, because of the ease of producing polycarbonate polyol (Aa1).

The polycarbonate polyol compound (Aa1) 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 compound (Aa1) 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 compound (Aa1) with the polyisocyanate compound (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 polycarbonate polyol compound (Aa1) more preferably has an Mn of 500 to 3,500, particularly 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.

From the viewpoints of substrate adhesion and breaking energy, the hydroxyl value of the polycarbonate polyol compound (Aa1) is preferably 20 to 300 mgKOH/g, more preferably 30 to 230 mgKOH/g, and even more preferably 45 to 200 mgKOH/g. The hydroxyl value is measured in accordance with JIS K 1557, Method B.

A method for producing a polycarbonate polyol compound (Aa1) from a polyol component 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 addition, a catalyst such as titanium tetrabutoxide may be used in the above reaction.

<Other polyols (Aa2)>
The polyol compound (Aa) may contain other polyols (Aa2) other than the polycarbonate polyol compound (Aa1) and the acidic group-containing polyol (Ac) described later. Such other polyols (Aa2) are preferably contained in an amount of less than 70 mass% relative to the total amount of the polyol compound (Aa), more preferably contained in an amount of less than 60 mass%, even more preferably contained in an amount of less than 50 mass%, and particularly 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 polyols (Aa2) 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 other polyols (Aa2) do not have to be contained in the polyol compound (Aa).

As the other polyols (Aa2), known polyols can be used. For example, polyether polyols such as polyester polyols, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random copolymers or block copolymers of ethylene oxide and propylene oxide, or ethylene oxide and butylene oxide; short-chain aliphatic diols 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; alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A; and diols such as bisphenol A, hydroquinone, bishydroxyethoxybenzene, and alkylene oxide adducts thereof.

The other polyols (Aa2) as described above may be commercially available or individually prepared. For example, by selecting appropriate raw materials and using the method described for (Aa1), a polycarbonate polyol having a glass transition temperature of less than -60°C or more than 0°C can be prepared.

From the viewpoint of hardness when the aqueous polyurethane resin dispersion is used as a coating film, it is preferable that the polyol compound (Aa) has an alicyclic structure such as a cyclohexane ring. In particular, it is preferable that the polycarbonate polyol compound (Aa1) contains an alicyclic structure. There is no limit to the number of ring members of the alicyclic structure as long as it is an aliphatic ring structure. Since it is easy to obtain as a raw material, it is preferable to design it so that it contains a 6-membered ring (cyclohexylene group). The proportion of the alicyclic structure contained in the polyol compound (Aa) is preferably 10 to 60% by weight, more preferably 12 to 50% by weight, based on the solid content of the entire polyol compound (Aa).

<Polyisocyanate Compound (Ab)>
As the polyisocyanate compound (Ab), known compounds 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 polyisocyanate compounds such as isocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4',4''-triphenylmethane triisocyanate, m-isocyanatophenylsulfonyl isocyanate, and p-isocyanatophenylsulfonyl isocyanate; aliphatic polyisocyanate compounds such as ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 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; Examples of the isocyanate include alicyclic polyisocyanate 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 compound (Ab) may have a structure that is partially or entirely derivatized by isocyanuration, carbodiimidization, biuretization, or the like.

Among the above polyisocyanate compounds (Ab), alicyclic polyisocyanate compounds are preferred from the viewpoint of adhesion to substrates, and 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) and/or isophorone diisocyanate (IPDI) are more preferred from the viewpoint of hardness and breaking energy.

The polyisocyanate compound (Ab) may be used alone or in combination with multiple types.

The amount of polyisocyanate compound (Ab) used is preferably such that the ratio (isocyanato group/hydroxyl group (molar ratio)) of the isocyanato group of polyisocyanate compound (Ab) to the hydroxyl group of the total polyol (total of polyol compound (Aa) and acidic group-containing polyol (Ac)) is 1.3 to 2.5, and particularly preferably 1.4 to 2.3.

<Acidic Group-Containing Polyol (Ac)>
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.

In the aqueous polyurethane resin dispersion, the total hydroxyl equivalent number of the polyol compound (Aa) and the acidic group-containing polyol (Ac) is preferably 50 to 4000. If the hydroxyl equivalent number is within this range, the aqueous polyurethane resin dispersion containing the obtained polyurethane resin is easily produced. From the viewpoint of the rupture energy of the coating film obtained from the aqueous polyurethane resin dispersion, the hydroxyl equivalent number is preferably 100 to 2500, more preferably 120 to 1500, and particularly preferably 150 to 1000.

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]].

<Neutralizing agent (Ad)>
The neutralizing agent (Ad) may be used alone or in combination of two or more kinds.

As the neutralizing agent (Ad), known neutralizing agents can be used. For example, non-volatile bases such as sodium hydroxide and potassium hydroxide; tertiary amine compounds such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine; secondary amine compounds such as dimethylamine, diethylamine, and dibutylamine; primary amine compounds such as ethylenediamine, methylamine, ethylamine, and butylamine; ammonia, etc. can be used.

The neutralizing agent (Ad) preferably has a boiling point of 200°C or less, more preferably in the range of -50 to 180°C, because it volatilizes and disappears from the polyurethane film at the temperature (usually 50 to 180°C) when the aqueous medium in the coating material composition is dried, resulting in even better adhesive strength. Since the aqueous acrylic-urethane composition of the present invention can be effective when dried at a low temperature of 100°C or less, a neutralizing agent that volatilizes at 100°C or less, for example 80°C or less, is preferred. When a dry coating film is obtained 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, and even more preferably 100°C or less.

When the neutralizing agent (Ad) is used, 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 aqueous polyurethane resin dispersion. When the amount of the neutralizing agent (Ad) 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 having both high substrate adhesion and high breaking energy can be obtained in a short time of several seconds to 1 hour under low-temperature drying at 100°C or less.

<Chain extender (Ae)>
The chain extender (Ae) is a compound having reactivity with the isocyanato group of the polyurethane prepolymer. The chain extender (Ae) may be used alone or in combination of two or more kinds.

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; water; and the like, with amine compounds being preferred.
As the chain extender (Ae), a polyamine compound (Ae1) having a total of three or more amino groups and/or imino groups in one molecule, for example, a triamine compound such as diethylenetriamine, bis(2-aminopropyl)amine, or bis(3-aminopropyl)amine, can be used.

The chain extender (Ae) in the present invention may contain at least one polyamine compound (Ae1) having a total of three or more amino groups and/or imino groups in one molecule. As an optional component, the chain extender (Ae) may contain other chain extenders (Ae2). Examples of other chain extenders (Ae2) include the above-mentioned diamines. In addition, when a polyurethane resin is used, it is preferable that the crosslinking point density is in the range of 0 to 1.0 mmol/g. If the crosslinking point density exceeds 1.0 mmol/g, the breaking energy of the coating film becomes low and the film formation speed becomes slow, making it unsuitable for low-temperature drying at 100°C or less.

The proportion of polyamine compound (Ae1) having a total of three or more amino groups and/or imino groups in one molecule of the chain extender (Ae) is preferably 0 to 90 mol%, more preferably 0 to 70 mol%, and even more preferably 0 to 60 mol%.

The amount of the chain extender (Ae) added is preferably equal to or less than the equivalent of the residual isocyanato group that serves as the chain extension starting point in the urethane prepolymer composed of the polyol compound (Aa), the polyisocyanate compound (Ab), the acidic group-containing polyol (Ac), and the neutralizing agent (Ad), and is more preferably 0.7 to 0.99 equivalents of the residual isocyanato group. If the chain extender is added in an amount exceeding the equivalent of the residual isocyanato group, the molecular weight of the chain-extended urethane polymer may decrease, resulting in a decrease in cohesive force, and the breaking energy of the coating film formed using the obtained aqueous polyurethane resin dispersion may decrease, resulting in a decrease in strength.

In the present invention, it is more preferable to use a chain extender (Ae) that does not contain an ether bond or an ester bond. By ensuring that the polyurethane resin in the resulting aqueous polyurethane resin dispersion does not contain an ether bond or an ester bond, it is possible to obtain good water resistance for a coating film formed using the aqueous polyurethane dispersion (before drying is complete: when the laminate of the substrate and coating film is held vertically, the coating film does not sag; for example, the coating film has a solids concentration of approximately 60 to 95% by mass).

Among the above 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. From the viewpoint of breaking energy, diamines are even more preferred.

<Polyurethane resin>
The polyurethane resin of the present invention has structural units derived from a polyol compound (Aa), a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), a neutralizing agent (Ad) and a chain extender (Ae). The polyurethane resin of the present invention preferably has the following characteristics.

<N(C=O)NH group concentration>
The concentration of N(C=O)NH groups contained in the aqueous polyurethane resin dispersion of the present invention is preferably 3% by mass or more and 13% by mass or less based on the solid content. The N(C=O)NH groups are generated by the reaction of a chain extender with an isocyanato group during the preparation process of the polyurethane. When the concentration of N(C=O)NH groups is within the above range, a coating film having excellent adhesion to a substrate can be obtained even when the aqueous acrylic-urethane composition is cured at a low temperature.

The N(C=O)NH group concentration in the aqueous polyurethane resin dispersion is calculated from the hydroxyl group concentration of the polyol compound (Aa) and the acidic group-containing polyol (Ac), the isocyanato group concentration of the polyisocyanate compound (Ab), and the hydroxyl group concentration and/or amino group concentration of the chain extender (Ae), and is preferably 3 to 13 mass%, more preferably 3 to 10 mass%, and even more preferably 3 to 8 mass%, from the viewpoint of adhesion to the substrate. The method for calculating the N(C=O)NH group concentration is as described in the Examples.

<Hardware segment>
Generally, polyurethane molecules contain parts called hard segments and soft segments. Hard segments aggregate together and affect the hardness of polyurethane resin, while soft segments have a high degree of freedom in deformation and therefore affect the flexibility and adhesion.
The soft segment in polyurethane is a portion derived mainly from a high molecular weight polyol, and the hard segment is a crystalline portion that can cause aggregation due to hydrogen bonds. Specifically, the hard segment is composed of a urethane group, a urea group, and a structure having a molecular weight of less than 250 that links urethane groups or urea groups together or between a urethane group and a urea group. The "structure having a molecular weight of less than 250" is preferably derived from at least one selected from a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), and a chain extender (Ae). The "structure having a molecular weight of less than 250" corresponds to, for example, the R portion when polyisocyanate is expressed as OCN-R-NCO. If the molecular weight of this portion is less than 250, the length of the molecule of the portion is sufficiently short, and a portion called an island where the hard segments are aggregated is sufficiently formed. The structure having a molecular weight of less than 250 linking urethane groups or urea groups together or linking a urethane group and a urea group is specifically a structure derived from at least one compound selected from among polyisocyanate compounds, polyol compounds, acidic group-containing polyols, and polyamine compounds, which are composed of urethane groups and/or urea groups and have a molecular weight of less than 250, from which an isocyanato group, a hydroxyl group, an amino group, or an imino group has been removed.

The content of the hard segment in the aqueous polyurethane resin dispersion is preferably 20 to 65 mass% based on the solid content, more preferably 25 to 65 mass%, and even more preferably 25 to 60 mass%. The method for calculating the content of the hard segment is as described in the examples.

<Alicyclic structure>
The polyurethane resin contained in the aqueous polyurethane resin dispersion preferably contains an alicyclic structure from the viewpoint of hardness when the aqueous acrylic urethane composition is made into a coating. The alicyclic structure is not limited in the number of ring members as long as it is an aliphatic ring structure. It is preferable to design it so that it contains a 6-membered ring (cyclohexylene group) because it is easy to obtain as a raw material. The alicyclic structure may be derived from any of the raw materials of the polyurethane, but is preferably derived from the polyol compound (Aa) and/or the polyisocyanate compound (Ab). Examples of the structural unit having an alicyclic structure include, as the polyol compound (Aa), a diol having an alicyclic structure in the main chain such as 1,4-cyclohexanedimethanol or a polycarbonate polyol obtained therefrom, and as the polyisocyanate compound (Ab), hydrogenated MDI, etc. The content ratio of the alicyclic structure is calculated based on the entire alicyclic structure contained in each of these structural units.

The content of the alicyclic structure in the aqueous polyurethane resin dispersion is preferably 10 to 60 mass% based on the solid content, and more preferably 12 to 50 mass%. If the content of the alicyclic structure is less than 10 mass%, the adhesion to the substrate tends to be low, and if the content of the alicyclic structure is more than 60 mass%, the breaking energy tends to be low. The method for calculating the content of the alicyclic structure is as explained in the examples.

<Aqueous Polyurethane Resin Dispersion>
The aqueous polyurethane resin dispersion contains a polyurethane resin and an aqueous medium, and the polyurethane resin is dispersed in the aqueous medium. As the aqueous medium, the same as that described for the oxazoline crosslinked acrylic emulsion (B) can be used.
In the aqueous polyurethane resin dispersion, the amount of the hydrophilic organic solvent in the aqueous medium is preferably 0 to 20% by mass, more preferably 0 to 15% by mass, and even more preferably 0 to 10% by mass.
Since the amount of the hydrophilic organic solvent used in the composition containing the aqueous polyurethane resin dispersion can be reduced in this manner, the composition of the present invention is an environmentally friendly material.

The pH of the aqueous polyurethane resin dispersion is preferably 5.0 to 10.0, more preferably 6.0 to 9.5, and even more preferably 6.5 to 9.0.

From the viewpoint of the breaking energy of a low-temperature dried coating film, the weight-average molecular weight (Mw) of the aqueous polyurethane resin dispersion is preferably 40,000 or more, and more preferably 100,000 or more. By setting it in this range, the coating film obtained by drying the composition at a temperature of 100°C or less exhibits superior breaking energy.

The proportion of polyurethane resin in the aqueous dispersion is preferably 5 to 60% by mass, and more preferably 20 to 50% by mass.

The acid value of the aqueous polyurethane resin dispersion is not particularly limited, but is preferably 12 to 40 mgKOH/g, more preferably 14 to 35 mgKOH/g, based on the solid content. If the acid value of the aqueous polyurethane resin dispersion is greater than 40 mgKOH/g based on the solid content, the dispersibility in an aqueous medium tends to deteriorate. If the acid value is less than 12 mgKOH/g based on the solid content, the adhesion to the substrate tends to decrease. 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 before the measurement. For example, when an organic amine is 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.

<Method for producing aqueous polyurethane resin dispersion>
The aqueous polyurethane resin dispersion can be produced by a known method such as that described in International Publication No. 2016/039396. For example, the following production method can be mentioned.
The first production method is a method in which all raw materials are mixed, reacted, and dispersed in an aqueous medium to obtain an aqueous polyurethane resin dispersion.
The second production method is a method in which all of the polyol components are reacted with a polyisocyanate to produce a prepolymer, the acidic groups of the prepolymer are neutralized, the prepolymer is dispersed in an aqueous medium, and a chain extender is reacted therewith to obtain an aqueous polyurethane resin dispersion.
As a method for producing the aqueous polyurethane resin dispersion, the above-mentioned second production method is preferred because it is easy to control the molecular weight.

In addition, when the resin has a blocked isocyanate structure, it can be introduced, for example, by the following production method.
The first production method is a method in which all of the raw materials other than the blocking agent (Bg) are mixed and reacted in the presence or absence of a urethanization catalyst to carry out a urethanization reaction, and finally, a blocking agent (Bg) is reacted in the presence or absence of a blocking catalyst to carry out a blocking reaction, thereby synthesizing a polyurethane prepolymer in which at least a portion of the terminal isocyanato groups are blocked.
The second production method is a method in which an isocyanate compound (Bb') is reacted with a blocking agent (Bg) in the presence or absence of a blocking catalyst to carry out a blocking reaction, thereby synthesizing a polyisocyanate compound in which some of the isocyanato groups are blocked, and then, in the presence or absence of a urethanization catalyst, the obtained blocked polyisocyanate compound is reacted with raw materials other than (Bb') and (Bg) to carry out a urethanization reaction, thereby synthesizing a polyurethane prepolymer.
The method for producing the aqueous polyurethane resin dispersion in these production methods is as described above.
Examples of the blocking agent 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 acetic 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 methyl ethyl ketoxime, amine-based agents such as diphenylaniline, aniline, and ethyleneimine, and pyrazole-based agents such as pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole.

<Production of Acrylic-Urethane Composition>
The acrylic-urethane composition of the present invention contains the aqueous polyurethane resin dispersion (A) and the oxazoline crosslinked acrylic emulsion (B) as essential components, but may contain other resins and/or other additives as necessary to form a coating material composition. The coating material composition is defined as a material that forms a coating film by applying to an electrodeposition coated surface, a steel plate, wood, or a plastic substrate with a spray, a brush, an applicator, a bar coater, or the like. In this specification, the term "coating material composition" includes not only a composition containing other resins, additives, etc., but also a composition consisting of the aqueous polyurethane resin dispersion (A) and the oxazoline crosslinked acrylic emulsion (B).

Examples of the other resins include olefin resins, polyester resins, vinyl chloride resins, nylon resins, and acrylic emulsions other than oxazoline crosslinked. Among these, acrylic emulsions other than oxazoline crosslinked, polyolefin emulsions, and polyester emulsions are preferred, and a coating material composition for fracture-resistant materials obtained by mixing at least one selected from these as an optional component is a preferred form.

Examples of the other additives that can be used include curing agents, crosslinking agents, surface conditioners, emulsifiers, thickeners, urethane catalysts, fillers, foaming agents, pigments, dyes, oil repellents, hollow foams, flame retardants, defoamers, leveling agents, and antiblocking 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.

The method for producing the coating material composition of the present invention is not particularly limited, and any known production method can be used. For example, the coating material composition is produced by stirring and mixing the aqueous polyurethane resin dispersion and, as optional components, the other resins and various additives described above.

In particular, in the present invention, a water-based acrylic urethane composition for use in a fracture-resistant material can be produced by a method including the following steps:
(I) a step of reacting a polyol compound (Aa), a polyisocyanate compound (Ab), and an acidic group-containing polyol (Ac) in the presence or absence of an organic solvent to obtain a polyurethane prepolymer;
(II) neutralizing the acid groups of the polyurethane prepolymer with a neutralizing agent (Ad);
(III) dispersing the polyurethane prepolymer in an aqueous medium;
(IV) a step of increasing the molecular weight of the polyurethane prepolymer with a chain extender (Ae) to obtain an aqueous polyurethane resin dispersion;
(V) a step of mixing a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc) to obtain an oxazoline crosslinked acrylic emulsion (B) with the aqueous polyurethane resin dispersion obtained in the step (IV); and optionally,
(VI) A step of removing the organic solvent following the step (IV) or (V).

In the coating material composition of the present invention, the mixing ratio of the total weight of the aqueous polyurethane resin dispersion (A) and the oxazoline crosslinked acrylic emulsion (B) to the other resin is not particularly limited as long as it does not impair the effects of the present invention. When the other resin is contained, from the viewpoint of substrate adhesion and breaking energy, the solid content mass ratio is preferably 98/2 to 10/90, more preferably 95/5 to 15/85, even more preferably 90/10 to 20/80, and particularly preferably 80/20 to 30/70.

<Curing method>
The coating material composition for fracture-resistant materials of the present invention can be cured by heating to a temperature of room temperature (20° C.) or higher and preferably 100° C. or lower, more preferably 80° C. or lower.
Specifically, the above-mentioned coating material composition for fracture-resistant materials can be applied to various plastic substrates such as electrodeposition coating 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 cured by holding the applied coating in an oven or heating tank at 100° C. or less, preferably 80° C. or less, for 1 to 120 minutes, preferably 1 to 60 minutes, and more preferably 1 to 45 minutes. The dry thickness of the coating film is preferably adjusted to 0.5 to 200 μm, more preferably 1 to 100 μm, even more preferably 5 to 50 μm, and particularly preferably 10 to 40 μm. 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 can be held, for example, at room temperature 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 dried at the same drying temperature and drying time, and then a top coat (which may be called a clear coat depending on the application) is applied and heat cured at 100°C or less, preferably 80°C or less, for 10 to 120 minutes, preferably 20 to 90 minutes, and more preferably 30 to 60 minutes.
One embodiment of the present invention is a coating film obtained by drying the coating material composition for a destruction-resistant material at 20°C to 100°C.

<Physical properties of coating film>
The breaking energy of the coating film obtained from the coating material composition of the present invention, measured by the method described in the Examples, is preferably 80 MPa or more, more preferably 90 MPa or more, and even more preferably 100 MPa or more.
The adhesion of the coating film obtained from the coating material composition of the present invention to the ABS resin substrate, measured by the method described in the Examples, is preferably 100/100(1) or more, more preferably 100/100(4). Here, in the present invention, the evaluation of the adhesion of the coating film is expressed as "n/100(m)". n means the number of squares remaining when at least one square peels off under the following test conditions, and m means the number of tests when peeling occurs. However, the maximum value of m is 4, and if no peeling occurs even after four repeated tests, it is expressed as 100/100(4). The conditions of the adhesion test are explained in detail in the Examples section.
Therefore, one embodiment of the present invention is a composition comprising: an aqueous polyurethane resin dispersion (A) in which a polyurethane resin having structural units derived from the polyol compound (Aa), the polyisocyanate compound (Ab), the acidic group-containing polyol (Ac), the neutralizing agent (Ad) and the chain extender (Ae) is dispersed in water; and an oxazoline crosslinked acrylic emulsion (B) having a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc); The composition has a breaking energy of 80 MPa or more, calculated using tensile properties measured in accordance with a method in accordance with JIS H7311 at a measurement temperature of 23°C, a humidity of 50%, and a tensile speed of 100 mm/min, and in the above-mentioned cross-cut peel test of a coating film on an ABS resin substrate, no peeling is observed after four tries (i.e., the result is expressed as 100/100(4)).

<Applications of destruction-resistant materials>
In the present invention, the fracture-resistant material is a material that is used as a protective agent for a substrate and that is itself resistant to destruction by physical shocks such as collisions, stone chips, and drops. For this reason, the fracture-resistant material is preferably a material that has high adhesion to the substrate and high breaking energy when formed into a coating film. Specific applications of the fracture-resistant material of the present invention include primer materials, base coat materials, etc.
The aqueous acrylic-urethane composition for destructive property materials of the present invention can be widely used as a floor coating, a coating for various plastic substrates such as polycarbonate resin, acrylic resin, polyethylene terephthalate (PET) resin, acrylonitrile butadiene styrene (ABS) resin, or rubber, a steel plate treatment agent, and a primer or base coat material for the exterior of metals such as automobiles, trucks, trains, and other vehicles, and is useful.

EXAMPLES 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.
The physical properties were measured as follows.

(1) Glass transition temperature (Tg) of polycarbonate polyol: Using a differential scanning calorimeter (DSC), the temperature was lowered to -100°C at 10°C/min, and then increased at 10°C/min, and the temperature at which the transition began was measured.
(2) N(C=O)NH concentration (%):
(i) When the number of moles of residual isocyanato groups in the polyurethane prepolymer before dispersion in water is greater than the number of moles of amino groups and/or imino groups in the chain extender polyamine:
It was calculated as follows: "N(C=O)NH concentration (%) = [(number of moles of amino and/or imino groups in polyamine) + [(number of moles of isocyanato groups in polyisocyanate compound) - (number of moles of total hydroxyl groups in polyol compound and acidic group-containing polyol) - (number of moles of amino and/or imino groups in polyamine)]/2] x 57.03 x 100". The concentration of N(C=O)NH formed by hydrolysis of isocyanato groups is added.
(ii) When the number of moles of residual isocyanato groups in the polyurethane prepolymer before dispersion in water is smaller than the number of moles of amino groups and/or imino groups in the chain extender polyamine:
It was calculated as follows: "N(C=O)NH concentration (%) = [(number of moles of isocyanato groups in polyisocyanate compound) - (total number of moles of hydroxyl groups in polyol compound and acidic group-containing polyol)] x 57.03 x 100." It was calculated assuming that all isocyanato groups react with amino groups and/or imino groups to generate N(C=O)NH groups.
(3) Hard segment content: The percentage (%) obtained by dividing the total mass of polyol, polyisocyanate, polyamine, and acidic group-containing polyol having a molecular weight of less than 300 contained in the aqueous polyurethane resin dispersion by the mass of the solid content was recorded.
(4) Content of alicyclic structure: The mass fraction of the alicyclic structure calculated from the charge ratio of each raw material of the aqueous polyurethane resin dispersion is shown. The mass fraction is based on the solid content of the aqueous polyurethane resin dispersion.
(5) The weight average molecular weight of the polyurethane resin in the aqueous polyurethane resin dispersion was measured by gel permeation chromatography (GPC), and a converted value obtained from a calibration curve of standard polystyrene prepared in advance was recorded.
(6) Acid value: Measured in accordance with the indicator titration method of JIS K 1557.

(7) Adhesion to ABS resin was evaluated as follows. DPnB was added as a film-forming aid to an aqueous acrylic-urethane composition (in the comparative example, polyurethane resin dispersion or acrylic emulsion) so that the total amount was 2% by mass, and mixed. The mixture was applied to an ABS resin substrate with a bar coater #18, dried by heating at 80°C for 45 minutes, and a checkerboard peel test was performed using the resulting coating film. The coating film was cut at 1 mm intervals vertically and horizontally in an area of 10 mm x 10 mm, and adhesive tape was applied, and the number of squares remaining on the surface of the ABS resin substrate when peeled off was visually counted and evaluated. This was repeated four times. When 15 out of 100 pieces remained in the first peel test, it was recorded as 15/100 (1), and when no peeling was observed until the second test and 85 out of 100 pieces remained in the third test, it was recorded as 85/100 (3). When no peeling was observed at all, it was recorded as 100/100 (4).
(8) The tensile properties of the acrylic-urethane resin film (in the comparative example, polyurethane resin film or acrylic film) were evaluated as follows. DPnB was added as a film-forming agent to an aqueous acrylic-urethane composition (in the comparative example, aqueous polyurethane resin dispersion or acrylic emulsion) so that the total amount was 2 mass %. The mixture was applied to a PET film so that the dry film thickness was 50 μm, and dried at 80 ° C for 2 hours to prepare an acrylic-urethane resin film (in the comparative example, polyurethane resin film or acrylic resin film). The elastic modulus, tensile strength, and elongation at break of the acrylic-urethane resin film (in the comparative example, polyurethane resin film or acrylic resin film) were measured by a method conforming to JIS K 7311. The measurement conditions were a measurement temperature of 23 ° C, humidity of 50%, and a tensile speed of 100 mm / min.
(9) The breaking energy was determined by integrating the stress from zero elongation to the breaking elongation on the elongation-stress curve.

[Synthesis Example 1]
<Production of aqueous polyurethane resin dispersion (A)>
ETERNACOLL (registered trademark) UH-200 (manufactured by Ube Industries; number average molecular weight 1958; hydroxyl value 57.3 mg KOH/g; polycarbonate diol obtained by reacting 1,6-hexanediol with carbonate ester, 1850 g), 2,2-dimethylolpropionic acid (129 g), and 4,4'-dicyclohexylmethane diisocyanate (841 g) were heated in dipropylene glycol dimethyl ether (DMM, 932 g) in the presence of dibutyltin dilaurate (0.9 g) under a nitrogen atmosphere at 80 to 95°C for 5 hours. Next, 3,5-dimethylpyrazole (DMPZ, 55.8 g) was added and heating was continued at the same temperature for 1.5 hours. The reaction mixture was cooled to 80° C., and triethylamine (97.4 g) was added thereto and mixed, and 3500 g of the mixture was added to water (4950 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (270 g) was added thereto to obtain an aqueous polyurethane resin dispersion (A).

[Synthesis Example 2]
<Production of aqueous polyurethane resin dispersion (B)>
ETERNACOLL (registered trademark) UM90 (1/3) (manufactured by Ube Industries; number average molecular weight 873; hydroxyl value 128.5 mg KOH/g; polycarbonate diol obtained by reacting 1,4-cyclohexanedimethanol, 1,6-hexanediol (molar ratio 1:3) with a carbonate ester, 350 g), 2,2-dimethylolpropionic acid (52.2 g), and 4,4'-dicyclohexylmethane diisocyanate (341 g) were heated in dipropylene glycol dimethyl ether (DMM, 262 g) under a nitrogen atmosphere at 80 to 95°C for 5 hours. The reaction mixture was cooled to 80°C, and triethylamine (39.3 g) was added and mixed, of which 416 g was added to water (578 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (34.3 g) and a 35% by mass aqueous solution of diethylenetriamine (16.7 g) were added to obtain an aqueous polyurethane resin dispersion (B).

[Synthesis Example 3]
<Production of Aqueous Polyurethane Resin Dispersion (C)>
ETERNACOLL (registered trademark) UM90 (3/1) (manufactured by Ube Industries; number average molecular weight 869; hydroxyl value 129.1 mgKOH/g; polycarbonate diol obtained by reacting 1,4-cyclohexanedimethanol, 1,6-hexanediol (molar ratio 3:1) with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (26.9 g), and 4,4'-dicyclohexylmethane diisocyanate (178 g) were heated in dipropylene glycol dimethyl ether (DMM, 131 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, of which 398 g was added to water (562 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (61.1 g) was added to obtain an aqueous polyurethane resin dispersion (C).

[Synthesis Example 4]
<Production of Aqueous Polyurethane Resin Dispersion (D)>
ETERNACOLL (registered trademark) UM90 (1/3) (manufactured by Ube Industries; number average molecular weight 873; hydroxyl value 128.5 mg KOH/g; polycarbonate diol obtained by reacting 1,4-cyclohexanedimethanol, 1,6-hexanediol (molar ratio 1:3) with a carbonate ester, 180 g), 2,2-dimethylolpropionic acid (26.8 g), and 4,4'-dicyclohexylmethane diisocyanate (177 g) were heated in dipropylene glycol dimethyl ether (DMM, 136 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, of which 429 g was added to water (596 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (65.8 g) was added to obtain an aqueous polyurethane resin dispersion (D).

[Synthesis Example 5]
<Production of aqueous polyurethane resin dispersion (E)>
ETERNACOLL (registered trademark) UH-200 (manufactured by Ube Industries; number average molecular weight 2011; hydroxyl value 55.8 mgKOH/g; polycarbonate diol obtained by reacting 1,6-hexanediol with carbonate ester, 301 g), 2,2-dimethylolpropionic acid (16.5 g), and isophorone diisocyanate (92.0 g) were heated in dipropylene glycol dimethyl ether (DMM, 135 g) under a nitrogen atmosphere at 80 to 95 ° C. for 5 hours. The reaction mixture was cooled to 80 ° C., and triethylamine (12.4 g) was added and mixed thereto, and 495 g of the mixture was added to water (745 g) under strong stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (29.4 g) was added to obtain an aqueous polyurethane resin dispersion (E). Various physical properties of the aqueous polyurethane resin dispersions (A) to (E) of Synthesis Examples 1 to 5 are shown in Table 1.

[Example 1]
<Preparation of Water-Based Acrylic-Urethane Composition (1) for Puncture-Resistant Materials>
Water (68 g) was added to and mixed with the aqueous polyurethane resin dispersion (A) (200 g), and then Nikasol (registered trademark) FX-2018 (manufactured by Nippon Carbide Industries; oxazoline crosslinked acrylic emulsion; hereinafter referred to as acrylic emulsion (X), 132 g) was added and mixed at room temperature to obtain an aqueous acrylic-urethane composition (1) for fracture-resistant materials. The above-mentioned physical property values of the obtained composition were measured. The results are shown in Table 2.

[Example 2]
<Preparation of Water-Based Acrylic-Urethane Composition (2) for Puncture-Resistant Materials>
Water (68 g) was added to the aqueous polyurethane resin dispersion (B) (200 g) and mixed, and then acrylic emulsion (X) (132 g) was mixed at room temperature to obtain an aqueous acrylic urethane composition (2) for a fracture-resistant material. The above-mentioned physical properties of the obtained composition were measured. The results are shown in Table 2.

[Example 3]
<Preparation of Water-Based Acrylic-Urethane Composition (3) for Puncture-Resistant Materials>
An aqueous acrylic-urethane composition (3) for a fracture-resistant material was obtained by mixing 200 g of the aqueous polyurethane resin dispersion (A) with 300 g of Nikasol (registered trademark) RX-7022E (manufactured by Nippon Carbide Industries; oxazoline crosslinked acrylic emulsion; hereinafter referred to as acrylic emulsion (Y)) at room temperature. The above-mentioned physical properties of the obtained composition were measured. The results are shown in Table 2.

[Example 4]
<Preparation of Water-Based Acrylic-Urethane Composition (4) for Puncture-Resistant Materials>
The aqueous polyurethane resin dispersion (C) (200 g) was mixed with the acrylic emulsion (Y) (300 g) at room temperature to obtain an aqueous acrylic urethane composition (4) for use in a fracture-resistant material. The above-mentioned physical properties of the obtained composition were measured. The results are shown in Table 2.

[Example 5]
<Preparation of Water-Based Acrylic-Urethane Composition (5) for Puncture-Resistant Materials>
The aqueous polyurethane resin dispersion (D) (200 g) was mixed with the acrylic emulsion (Y) (300 g) at room temperature to obtain an aqueous acrylic urethane composition (5) for use in a fracture-resistant material. The above-mentioned physical properties of the obtained composition were measured. The results are shown in Table 2.

[Example 6]
<Preparation of Water-Based Acrylic-Urethane Composition (6) for Puncture-Resistant Materials>
The aqueous polyurethane resin dispersion (E) (200 g) was mixed with the acrylic emulsion (Y) (300 g) at room temperature to obtain an aqueous acrylic urethane composition (6) for use as a fracture-resistant material. The above-mentioned physical properties of the obtained composition were measured. The results are shown in Table 2.

[Comparative Examples 1 to 7]
The above physical property values were measured for the aqueous polyurethane resin dispersions (A), (B), (C), (D) and (E) obtained in Synthesis Examples 1 to 5. The above physical property values were also measured for the acrylic emulsions (X) and (Y). The results are shown in Table 2.

As shown in Examples 1 to 6 in Table 2, the coating film obtained by applying and heating the composition for a fracture-resistant material of the present invention has high adhesion to ABS substrates and high breaking energy. In addition, the elastic modulus can be controlled by combining the aqueous polyurethane resin dispersion and the oxazoline crosslinked acrylic emulsion.
On the other hand, an aqueous polyurethane resin dispersion having a urethane bond, a urea bond, and a carbonate bond and a specific amount of blocked isocyanato groups, which has been previously disclosed by the present inventors, exhibits poor adhesion to a substrate when dried at 80°C (see Comparative Example 1; corresponding to Patent Document 5).
When an aqueous polyurethane resin dispersion containing a large amount of alicyclic structures is dried at 80° C., cracks tend to form in the coating film, and it is difficult to form a coating film with high breaking energy (Comparative Example 3 and Comparative Example 4).
When the aqueous polyurethane resin dispersion or the oxazoline crosslinked acrylic emulsion was used alone, the adhesion to the substrate was low, but by mixing the two, high adhesion to the substrate was achieved.

The water-based acrylic-urethane composition for fracture-resistant materials of the present invention has excellent adhesion to substrates when dried at low temperatures of 100°C or less, and produces coatings with high breaking energy. It is therefore expected to contribute to the reduction of greenhouse gas emissions by allowing low-temperature drying of floor coats, coatings for plastic substrates or rubber, steel plate treatment agents, vehicle primer layers, etc.

Claims (18)

An aqueous acrylic urethane composition for a fracture-resistant material, comprising: an aqueous polyurethane resin dispersion (A) and an oxazoline crosslinking acrylic emulsion (B),
The aqueous polyurethane resin dispersion (A) has structural units derived from a polyol compound (Aa), a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), a neutralizing agent (Ad), and a chain extender (Ae),
The polyol compound (Aa) of the aqueous polyurethane resin dispersion (A) contains a polycarbonate polyol having a number average molecular weight of 400 to 5,000,
the aqueous polyurethane resin dispersion (A) contains an alicyclic structure, and the content of the alicyclic structure is 10 to 60% by weight based on the solid content of the aqueous polyurethane resin dispersion (A);
The oxazoline crosslinked acrylic emulsion (B) is an aqueous acrylic-urethane composition, which is an acrylic emulsion having a polymer (Ba) having an acrylic skeleton in its main chain and a functional group in its side chain that reacts with an oxazoline group, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc). The aqueous acrylic urethane composition for fracture-resistant materials according to claim 1, wherein the oxazoline group contained in the oxazoline crosslinking acrylic emulsion (B) is at least one selected from the group consisting of 2-oxazoline groups, 3-oxazoline groups, and 4-oxazoline groups. 3. The aqueous acrylic-urethane composition for fracture-resistant materials according to claim 1 or 2, wherein the weight average molecular weight of the oxazoline crosslinking acrylic emulsion (B) is 100,000 or more and 2,000,000 or less . The aqueous acrylic urethane composition for fracture-resistant materials according to any one of claims 1 to 3, wherein the acrylic skeleton in the oxazoline crosslinking acrylic emulsion (B) has at least one component selected from an acrylic acid ester and/or a methacrylic acid ester having a hydrocarbon group having 1 to 20 carbon atoms as a constituent unit. The aqueous acrylic-urethane composition for fracture-resistant materials according to any one of claims 1 to 4, wherein the content of the oxazoline crosslinked acrylic emulsion (B) is 2 to 80 mass% on a solids basis with respect to the total amount of the composition. The aqueous acrylic urethane composition for a fracture-resistant material according to any one of claims 1 to 5, wherein the amount of oxazoline groups contained in the oxazoline crosslinking acrylic emulsion (B) is 0.0002 to 0.4 mmol/g on a solids basis relative to the total amount of the emulsion. The water-based acrylic-urethane composition for fracture-resistant material according to any one of claims 1 to 6 , wherein the glass transition temperature of said polycarbonate polyol is -60°C to 0°C. The aqueous acrylic urethane composition for fracture-resistant materials according to any one of claims 1 to 7, wherein the polyol constituting the polycarbonate polyol is selected from 1,6-hexanediol and/or 1,4-cyclohexanedimethanol. The aqueous acrylic urethane composition for fracture-resistant materials according to any one of claims 1 to 8 , wherein the polyisocyanate compound (Ab) of the aqueous polyurethane resin dispersion (A) is an alicyclic polyisocyanate. The aqueous acrylic urethane composition for fracture-resistant materials according to any one of claims 1 to 9 , wherein the aqueous polyurethane resin dispersion (A) has an acid value of 12 to 40 mg KOH/g. The aqueous acrylic urethane composition for fracture-resistant materials according to any one of claims 1 to 10 , wherein the content of the hard segment in the aqueous polyurethane resin dispersion (A) is 20 to 65 mass% based on the solid content. A coating material composition for destruction-resistant material properties, comprising the aqueous acrylic-urethane composition for destruction-resistant material according to claim 1 or 2 , and optionally further comprising other resins and/or additives. The water-based acrylic-urethane composition for anti-fracture properties materials according to any one of claims 1 to 11 for coatings of plastic materials, for exterior primers or base coats of metals. A coating film obtained by drying the aqueous acrylic-urethane composition for a destruction-resistant material according to any one of claims 1 to 11 . A method for producing a coating film, comprising a step of drying the aqueous acrylic-urethane composition for a fracture-resistant material according to any one of claims 1 to 11 at 20°C to 100°C. 10. Use of the coating film obtained by the method according to claim 15 as a floor coat, a coating for plastics or rubber, a steel plate treatment agent, or a primer or base coat for metal exteriors. (I) a step of reacting a polyol compound (Aa), a polyisocyanate compound (Ab), and an acidic group-containing polyol (Ac) in the presence or absence of an organic solvent to obtain a polyurethane prepolymer;
(II) neutralizing the acid groups of the polyurethane prepolymer with a neutralizing agent (Ad);
(III) dispersing the polyurethane prepolymer in an aqueous medium;
(IV) a step of increasing the molecular weight of the polyurethane prepolymer with a chain extender (Ae) to obtain an aqueous polyurethane resin dispersion;
(V) a step of mixing a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc) to obtain an oxazoline crosslinked acrylic emulsion (B) with the aqueous polyurethane resin dispersion obtained in the step (IV); and optionally,
(VI) A method for producing an aqueous acrylic-urethane composition for use in a fracture-resistant material, comprising the step of removing the organic solvent following the step (IV) or (V),
The polyol compound (Aa) contains a polycarbonate polyol having a number average molecular weight of 400 to 5000,
The aqueous polyurethane resin dispersion contains an alicyclic structure, and the content of the alicyclic structure is 10 to 60% by weight based on the solid content of the aqueous polyurethane resin dispersion . A composition comprising: an aqueous polyurethane resin dispersion (A) having structural units derived from a polyol compound (Aa), a polyisocyanate compound (Ab), an acidic group-containing polyol (Ac), a neutralizing agent (Ad) and a chain extender (Ae); and an oxazoline crosslinked acrylic emulsion (B) having a polymer (Ba) having an acrylic skeleton in its main chain and a functional group reactive with an oxazoline group in its side chain, a water-soluble or water-dispersible polymer (Bb) having an acrylic skeleton in its main chain and an oxazoline group, and an aqueous medium (Bc);
The polyol compound (Aa) of the aqueous polyurethane resin dispersion (A) contains a polycarbonate polyol having a number average molecular weight of 400 to 5,000,
the aqueous polyurethane resin dispersion (A) contains an alicyclic structure, and the content of the alicyclic structure is 10 to 60% by weight based on the solid content of the aqueous polyurethane resin dispersion (A);
A water-based acrylic-urethane composition which forms a coating film at low temperatures of 20°C to 100°C, and has a breaking energy of 80 MPa or more as calculated from tensile properties measured in accordance with JIS K 7311 at a measurement temperature of 23°C, a humidity of 50%, and a tensile speed of 100 mm/min., and which, in a cross-cut peel test of the coating film on an ABS resin substrate, shows no peeling after four tries.