Water-based coating agent

Abstract

This invention provides polyurethane urea particles that, when used as a component of water-based coating agents, easily form a matte-finish film with good abrasion resistance, flexibility at low temperatures, heat resistance, and a soft feel. [Solution] The polyurethane urea particles are reaction products of a reactive component containing a polyol, a polyamine, and a polyisocyanate. The polyisocyanate contains a polyisocyanate crosslinking agent with more than two functional groups. The polyurethane urea particles have a crosslinking density of 0.30 mol / kg or more and 0.80 mol / kg or less derived from the polyfunctional component in the reactive component with more than two functional groups. The urea group content in the polyurethane urea particles is 0.50 mol / kg or more and 2.00 mol / kg or less. Furthermore, the volume-average particle diameter of the polyurethane urea particles is 1 μm or more and 30 μm or less.

Description

Technical Field

[0001] The present invention relates to polyurethane-urea particles, an aqueous dispersion of polyurethane-urea particles, and an aqueous coating agent.

Background Art

[0002] Conventionally, for the purpose of protection and improvement of aesthetics, various objects have been painted with paints on their surfaces. For example, for the surfaces of objects that are touched by human eyes and hands, such as transportation equipment, buildings, electrical products, furniture, toys, and miscellaneous goods, a matte paint may be used to suppress gloss and luster and express a calm appearance. In recent years, from the viewpoints of environmental problems and safety, a conversion to an aqueous paint using an aqueous medium containing water as a liquid medium has been attempted, and the demand for an aqueous matte paint has been increasing.

[0003] On the other hand, polyurethane-based resins such as polyurethane resins, polyurea resins, and polyurethane-urea resins are widely used in coating agents such as paints and inks. The polyurethane-based resin is not limited to being used as a binder resin blended in a coating agent, and a particulate polyurethane-based resin also called polyurethane beads may be blended in a coating agent as a filler for expressing the above-mentioned matte finish.

[0004] For example, Patent Document 1 proposes a matte paint using a resin composition containing a polyurethane aqueous dispersion having an average particle diameter of 1.5 to 4.μm and a polyurethane aqueous dispersion having an average particle diameter of 0.01 to 1.0μm. Further, Patent Document 2 proposes a matte paint containing a polyurethane-urea aqueous dispersion which is a reaction product of a polymer polyol, a compound having an active hydrogen and a hydrophilic group, a dihydric alcohol, a polyisocyanate, and a predetermined polyamine.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The matte coatings proposed in the aforementioned Patent Documents 1 and 2 do not necessarily form films with good heat resistance, and there is room for improvement. Furthermore, in the case of aqueous coating agents using polyurethane resin particles, in addition to being able to form films with good abrasion resistance, it is sometimes required that the film has flexibility at low temperatures (e.g., -10°C) and heat resistance that does not easily impair the matte appearance even after heating to, for example, around 200°C. In particular, there is a trade-off relationship between abrasion resistance and flexibility at low temperatures, and pursuing one tends to result in a decline in the other. Moreover, it is sometimes required that the film be able to form a film with properties that can express a soft touch (feel) that creates a sense of luxury (hereinafter referred to as soft feel).

[0007] Therefore, the present invention aims to provide polyurethane urea particles that, when used as a component of an aqueous coating agent, readily form a matte-finish film with good abrasion resistance, flexibility at low temperatures, heat resistance, and a soft feel. [Means for solving the problem]

[0008] The present invention provides polyurethane urea particles which are reaction products of a reactive component comprising a polyol, a polyamine, and a polyisocyanate, wherein the polyisocyanate comprises a polyisocyanate crosslinking agent having more than 2 functional groups, the crosslinking density derived from the polyfunctional component having more than 2 functional groups in the reactive component is 0.30 mol / kg or more and 0.80 mol / kg or less, the urea group content in the polyurethane urea particles is 0.50 mol / kg or more and 2.00 mol / kg or less, and the volume average particle diameter is 1 μm or more and 30 μm or less. [Effects of the Invention]

[0009] According to the present invention, polyurethane urea particles that, when used as a component of an aqueous coating agent, readily form a matte-finish film with good abrasion resistance, flexibility at low temperatures, heat resistance, and soft feel. [Brief explanation of the drawing]

[0010] [Figure 1] This is an SEM image of the polyurethane urea particles used in Example 1. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. In this disclosure, "functional group" in the description of polyurethane urea particles means a functional group that contributes to urethane bonding or urea bonding. Specific examples of functional groups include hydroxyl groups, amino groups, and isocyanate groups. The functional group for polyols is a hydroxyl group, the functional group for polyamines is an amino group, and the functional group for polyisocyanates is an isocyanate group. In this disclosure, "number of functional groups" means the number of functional groups in one molecule.

[0012] <Polyurethane urea particles> Polyurethane urea particles of one embodiment of the present invention (hereinafter sometimes simply referred to as "polyurethane urea particles") are reaction products of a reactive component containing a polyol, a polyamine, and a polyisocyanate. The polyisocyanate used in the reactive component contains a polyisocyanate crosslinking agent having more than two functional groups. In addition to the polyisocyanate crosslinking agent having more than two functional groups, the reactive component may also contain other polyfunctional components having more than two functional groups. The polyurethane urea particles have a crosslinking density derived from the polyfunctional component having more than two functional groups in the reactive component that is between 0.30 mol / kg and 0.80 mol / kg. Furthermore, the urea group content in the polyurethane urea particles is between 0.50 mol / kg and 2.00 mol / kg. Moreover, the volume-average particle diameter of the polyurethane urea particles is between 1 μm and 30 μm.

[0013] By using polyurethane urea particles having the above configuration as a component of an aqueous coating agent (hereinafter sometimes simply referred to as "coating agent"), it is possible to form a film with a matte appearance. Furthermore, the film tends to have good abrasion resistance, flexibility at low temperatures (e.g., -10°C), heat resistance that does not easily impair the matte appearance even after heating to, for example, around 200°C, and a soft feel that can express a soft touch that creates a sense of luxury. For this reason, the above polyurethane urea particles are suitable as a component of coating agents such as paints, inks, and surface treatment agents. The reactive components that form the polyurethane urea particles will be described below, followed by a description of the characteristics of the polyurethane urea particles, such as the crosslinking density, urea group content, and volume-average particle diameter.

[0014] (Polyol) Polyols are compounds that have two or more hydroxyl groups in a single molecule. Polyols are compounds that, through reaction with polyisocyanates, produce urethane bonds in polyurethane urea particles.

[0015] Examples of polyols include high molecular weight polyols and low molecular weight polyols. In this disclosure, high molecular weight polyols are a group of polyols with a higher molecular weight than low molecular weight polyols. Low molecular weight polyols are a group of polyols with a lower molecular weight than high molecular weight polyols. As high molecular weight polyols, polyols with a number average molecular weight of 500 or more can be suitably used. As low molecular weight polyols, polyols with a number average molecular weight of less than 500 can be suitably used. From the viewpoint of easily obtaining polyurethane urea particles that constitute a soft segment and have good physical properties (for example, good flexibility at low temperatures and good soft feel), it is preferable that the polyol includes at least a high molecular weight polyol.

[0016] The number-average molecular weight (hereinafter sometimes abbreviated as Mn) of the polymeric polyol is preferably between 500 and 5,000, and more preferably between 1,000 and 4,000. The number-average molecular weight (Mn) of the polymeric polyol refers to the number-average molecular weight on a standard polystyrene basis, measured by gel permeation chromatography (GPC). Specifically, this is performed by GPC analysis using tetrahydrofuran (THF) as the mobile phase (instrument: "GPC-8020" manufactured by Tosoh Corporation; columns: Super AW2500 + AW3000 + AW4000 + AW5000; the same applies to the following examples).

[0017] The polymeric polyol can be any polymeric polyol having two or more hydroxyl groups in one molecule, but it is preferably a polymeric diol having two hydroxyl groups. Examples of polymeric polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and polymethacrylate polyols. One or more of these polymeric polyols can be used.

[0018] Examples of polyether polyols include those obtained by polymerizing or copolymerizing one or more selected from the group consisting of alkylene oxides and heterocyclic ethers. Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide. Examples of heterocyclic ethers include tetrahydrofuran.

[0019] Specific examples of polyether polyols include polyethylene glycol, polypropylene glycol, block or random polyethylene glycol-polytetramethylene glycol copolymers, polytrimethylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol. One or more of these polyether polyols can be used.

[0020] Examples of the polyester polyol include those obtained by polycondensing one or more selected from the group consisting of aliphatic dicarboxylic acids and aromatic dicarboxylic acids with glycols. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, etc. Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, etc. Examples of the glycol include ethylene glycol (alias: 1,2-ethanediol), 1,2-propylene glycol (alias: 1,2-propanediol), 1,3-propylene glycol (alias: 1,3-propanediol), 1,3-butylene glycol (alias: 1,3-butanediol), 1,4-butylene glycol (alias: 1,4-butanediol), 1,6-hexamethylene glycol (alias: 1,6-hexanediol), neopentyl glycol (alias: 2,2-dimethyl-1,3-propanediol), 1,4-bishydroxymethylcyclohexane, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,8-octanediol, 1,8-nonanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, 1,10-decanediol, isosorbide, etc. One or more of these glycols can be used.

[0021] Specific examples of the polyester polyol include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butylene adipate diol, polyneopentyl / hexyl adipate diol, poly-3-methylpentane adipate diol, and polybutylene isophthalate diol. Further, as the polyester polyol, a polylactone polyol can also be used. Examples of the polylactone polyol include polycaprolactone diol and poly-3-methylvalerolactone diol. One or more of the polyester polyols listed above can be used.

[0022] The polycarbonate polyol can include those obtained by condensing glycol (diol) while subjecting it to a dealcoholization reaction with a dialkyl carbonate. Examples of the glycol can include the glycols described in the above explanation of the polyester polyol. Examples of the dialkyl carbonate can include dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0023] Specific examples of polycarbonate polyols include, for example, polytetramethylene carbonate diol (1,4-butanediol-based polycarbonate polyol), polypentamethylene carbonate diol (1,5-pentanediol-based polycarbonate polyol), polyneopentyl carbonate diol, polyhexamethylene carbonate diol (1,6-hexanediol-based polycarbonate polyol), poly(1,4-cyclohexanedimethylene carbonate) diol, poly2- Examples include methyl-1,3-propanediol-based polycarbonate polyols, 3-methyl-1,5-pentanediol-based polycarbonate polyols, 2-methyl-1,8-octanediol-based polycarbonate polyols, 3-methyl-1,8-octanediol-based polycarbonate polyols, 1,9-nonanediol-based polycarbonate polyols, 1,10-decanediol-based polycarbonate polyols, and random / block copolymers thereof. Examples of copolymers include poly(tetramethylene / decamethylene)carbonatediol (1,4-butanediol and 1,10-decanediol-based polycarbonate polyol), poly(pentamethylene / hexamethylene)carbonatediol (1,5-pentanediol and 1,6-hexanediol-based polycarbonate polyol), (3-methyl-1,5-pentanediol-based and 1,6-hexanediol-based polycarbonate polyol, 2-methyl-1,3-propanediol and 1,4-butanediol polycarbonate polyol, 1,3-propanediol and 1,4-butanediol polycarbonate polyol, etc. One or more of the polycarbonate polyols listed above can be used.

[0024] Examples of polyolefin polyols include polybutadiene glycol, polyisoprene glycol, and their hydrides. One or more of these polyolefin polyols can be used. Examples of polymethacrylate polyols include α,ω-polymethyl methacrylate diol and α,ω-polybutyl methacrylate diol. One or more of these polymethacrylate polyols can be used.

[0025] The polyol described above preferably contains at least one polymer polyol selected from the group consisting of polyether polyols and polycarbonate polyols. Furthermore, it is more preferable that the polyol is at least one polymer polyol selected from the group consisting of polyether polyols and polycarbonate polyols. By using polyurethane urea particles, which are reaction products of a reactive component containing a polyether polyol and / or a polycarbonate polyol, it is easy to prepare a coating agent capable of forming a film with good abrasion resistance, flexibility at low temperatures, heat resistance, and soft feel. It is also possible to form a film that is resistant to hydrolysis and easy to prepare a coating agent with good storage stability. When the polyol contains a polyether polyol and a polycarbonate polyol, the preferred mass ratio of polyether polyol to polycarbonate polyol is 5:95 to 95:5, and more preferably 10:90 to 90:10.

[0026] The number-average molecular weight of the low molecular weight polyol should be less than 500 (preferably less than 250). The number-average molecular weight of the low molecular weight polyol is the arithmetic mean of the molecular weights calculated from the formula weight. The low molecular weight polyol may also be used as a chain extender to react with a urethane-based prepolymer having isocyanate groups at the ends. The urethane-based prepolymer having isocyanate groups at the ends is a urethane-based prepolymer obtained by reacting a polyisocyanate with a component containing a polyol and / or polyamine such that the ends are isocyanate groups.

[0027] Examples of low molecular weight polyols include low molecular weight polyols with two functional groups and low molecular weight polyols with more than two functional groups. One or more of these low molecular weight polyols can be used.

[0028] Low molecular weight polyols with two functional groups are diol compounds that have two hydroxyl groups in one molecule. Examples of diol compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, hexylene glycol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 1,9-nonanediol, 1,8-nonanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, 1,10-decanediol, isosorbide, 1,4-cyclohexanedimethanol, 2-ethyl-1,3-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, spiroglycol, and neopentyl glycol. Furthermore, as diol compounds, those having an acidic group can also be used, from the viewpoint of improving the dispersion stability of polyurethane urea particles in an aqueous medium. Examples of diol compounds having an acidic group include dimethylolacetic acid, dimethylolpropionic acid, and dimethylolbutanoic acid. One or more of the diol compounds listed above can be used.

[0029] Low molecular weight polyols with more than two functional groups are compounds that can create crosslinked structures in polyurethane urea particles and affect the crosslinking density. Suitable low molecular weight polyols with more than two functional groups include trifunctional or higher polyols having three or more hydroxyl groups in a single molecule. Examples of trifunctional or higher polyols include glycerin, trimethylolethane, trimethylolpropane, butanetriol, pentanetriol, hexanetriol, heptanetriol, octantriol, diglycerin, pentaerythritol, and dipentaerythritol. One or more of these trifunctional or higher polyols can be used.

[0030] The content of high molecular weight polyols relative to the total mass of the reactive components is preferably 45% to 80% by mass, more preferably 47% to 78% by mass, and even more preferably 50% to 75% by mass. The content of low molecular weight polyols relative to the total mass of the reactive components is preferably 0% to 15% by mass, and more preferably 0% to 10% by mass. Furthermore, the ratio of the amount of high molecular weight polyols to the total amount of polyols used as reactive components is preferably 70% to 100% by mass, and more preferably 80% to 100% by mass.

[0031] (Polyamines) Polyamines are compounds that have a total of two or more amino groups (primary or secondary amino groups, etc.) in one molecule. Polyamines are compounds that, upon reaction with polyisocyanates, produce urea bonds in polyurethane urea particles. Polyamines may also be used as chain extenders to react with urethane-based prepolymers having isocyanate groups at their terminals. Examples of polyamines include polyamines with two functional groups and polyamines with more than two functional groups. One or more of these polyamines can be used. Polyamines may also have functional groups other than amino groups. Specifically, examples include alkanolamines having hydroxyl groups.

[0032] Polyamines with two functional groups are diamine compounds that have two amino groups in one molecule. As mentioned above, these diamine compounds also include alkanol diamines, which have two amino groups and one or more hydroxyl groups in one molecule. Examples of polyamines with two functional groups include chain aliphatic diamines, cyclic aliphatic diamines, aromatic diamines, and hydrazines. One or more of these diamine compounds can be used. Examples of chain aliphatic diamines include short-chain diamines and long-chain diamines. Here, short-chain diamines are chain aliphatic diamines with a number-average molecular weight (Mn) of less than 500. Long-chain diamines are chain aliphatic diamines with a number-average molecular weight (Mn) of 500 or more. The number-average molecular weight of these chain aliphatic diamines is the arithmetic mean of the molecular weights calculated from the formula weights.

[0033] Examples of short-chain diamines include methylenediamine, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, octamethylenediamine, trimethylhexamethylenediamine, N-(β-aminoethyl)ethanolamine, 1,3-diamino-2-propanol, and 2,2'-(ethylenebisimino)bisethanol. One or more of these short-chain diamines can be used. Examples of long-chain diamines include polyalkylenediamines (long-chain alkylenediamines), poly(ethylene glycol)diamine, and polyoxypropylenediamine. One or more of these long-chain diamines can be used.

[0034] Examples of cyclic aliphatic diamines (alicyclic diamines) include cyclopentanediamine, cyclohexanediamine, 4,4-diaminodicyclohexylmethane, 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, bis(aminomethyl)norbornane, piperazine, and bis(3-aminopropyl)piperazine. One or more of these cyclic aliphatic diamines can be used.

[0035] Examples of aromatic diamines include phenylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(phenylamine), 4,4'-diaminodiphenyl ether, metaxylenediamine, 4,4'-diaminodiphenyl sulfone, and 3,5-diaminobenzyl alcohol. One or more of these aromatic diamines can be used.

[0036] Examples of hydrazines include hydrazine, carbohydrazide, adipic acid dihydrazide, sebacate acid dihydrazide, and phthalate dihydrazide. One or more of these hydrazines can be used.

[0037] Polyamines with more than two functional groups are preferred if they have three or more amino groups in one molecule and are trifunctional or higher. Polyamines with more than two functional groups are compounds that can create crosslinked structures in polyurethane urea particles and affect the crosslinking density. Examples of trifunctional or higher polyamines include diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, N,N'-bis(3-aminopropyl)ethylenediamine, and 2-aminoethyl-3-aminopropylamine. One or more of these trifunctional or higher polyamines can be used.

[0038] The polyamine content relative to the total mass of the reactive components is preferably 1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 9% by mass or less, and even more preferably 1% by mass or more and 8% by mass or less.

[0039] (Polyisocyanate) Polyisocyanates are compounds having two or more isocyanate groups in a single molecule. At least two polyisocyanate crosslinking agents (hereinafter sometimes simply referred to as "polyisocyanate crosslinking agents") with more than two functional groups are used as polyisocyanates. In addition to these polyisocyanate crosslinking agents with more than two functional groups, other polyisocyanates (hereinafter sometimes referred to as "other polyisocyanates") may also be used. Other polyisocyanates are polyisocyanates with two functional groups, i.e., diisocyanate compounds.

[0040] As a polyisocyanate crosslinking agent having more than two functional groups, a polyisocyanate crosslinking agent having three or more functional groups is preferred. Furthermore, as a polyisocyanate crosslinking agent, at least one selected from the group consisting of adduct-type polyisocyanates, biuret-type polyisocyanates, and isocyanurate-type polyisocyanates is more preferred. By crosslinking polyurethane urea particles with these polyisocyanate crosslinking agents, a film with better abrasion resistance and heat resistance can be formed.

[0041] Examples of adduct-type polyisocyanates include adducts (adducts) of a bifunctional polyisocyanate (i.e., a diisocyanate compound) and a compound having three or more active hydrogen groups in its molecule (trifunctional or more polyols, polyamines, or polythiols). Examples of biuret-type polyisocyanates or isocyanurate-type polyisocyanates include trimers (biuret structure or isocyanurate structure) of a bifunctional polyisocyanate (i.e., a diisocyanate compound). Examples of the diisocyanate compounds in adduct-type, biuret-type, or isocyanurate-type polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), m-xylylene diisocyanate (XDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated XDI). Among these, chain-type aliphatic diisocyanates such as PDI and HDI, and cyclic aliphatic (alicyclic) diisocyanates such as IPDI are preferred.

[0042] Commercially available polyisocyanate crosslinking agents may be used. Examples of commercially available adduct-type polyisocyanates include Asahi Kasei Corporation's "Duranate" (registered trademark) AE700-100, and Mitsui Chemicals, Inc.'s "Takenate" (registered trademark) D-110N, D-120N, and D-140N. Examples of commercially available biuret-type polyisocyanates include Asahi Kasei Corporation's "Duranate" (registered trademark) 24A-100 (manufactured by Asahi Kasei Corporation), and Mitsui Chemicals, Inc.'s "Takenate" (registered trademark) D-165N and NP1100. Examples of commercially available isocyanurate-type polyisocyanates include Asahi Kasei Corporation's "Duranate" (registered trademark) TMA-00, TPA-100, TKA-100, TLA-100, and TSS-100; and Mitsui Chemicals, Inc.'s "Takenate" (registered trademark) D-127N and "Stavio" (registered trademark) D-370N.

[0043] The isocyanate group (NCO) content of polyisocyanate crosslinking agents with more than two functional groups (hereinafter sometimes referred to as "NCO%") is preferably 5% by mass or more and 30% by mass or less, and more preferably 8% by mass or more and 25% by mass or less.

[0044] Other polyisocyanates (diisocyanate compounds) that can be used include aliphatic diisocyanates and aromatic diisocyanates. Furthermore, urethane prepolymers (urethane prepolymers having isocyanate groups at the ends) obtained by reacting these diisocyanate compounds with polyols and / or polyamines such that the ends are isocyanate groups can also be used. Examples of aliphatic diisocyanates include chain-type aliphatic polyisocyanates (chain-type aliphatic diisocyanates) and cyclic aliphatic (alicyclic) polyisocyanates (cyclic aliphatic (alicyclic) diisocyanates). One or more other polyisocyanates can also be used.

[0045] Specific examples of chain-type aliphatic diisocyanates include, for example, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), and 1,10-decamethylene diisocyanate. One or more of these chain-type aliphatic diisocyanates can be used.

[0046] Specific examples of cyclic aliphatic diisocyanates include, for example, 1,4-cyclohexane diisocyanate, 4,4'-methylenebiscyclohexyl diisocyanate (hydrogenated MDI), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated XDI), 1-methylcyclohexane-2,4-diisocyanate (hydrogenated TDI), and norbornene diisocyanate. One or more of these cyclic aliphatic diisocyanates can be used.

[0047] Specific examples of aromatic diisocyanates include, for example, 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-MDI, 2,4'-MDI, 2,4-tolylene diisocyanate (TDI), 2,6-TDI, m-xylylene diisocyanate (XDI), 1,4-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, and 1,5-naphthalene diisocyanate. One or more of these aromatic diisocyanates can be used.

[0048] The polyisocyanate preferably contains at least one aliphatic polyisocyanate selected from the group consisting of chain-type aliphatic polyisocyanates and cyclic aliphatic polyisocyanates. Furthermore, it is even more preferable that the polyisocyanate is at least one aliphatic polyisocyanate selected from the group consisting of chain-type aliphatic polyisocyanates and cyclic aliphatic polyisocyanates. Aliphatic polyisocyanates tend to have a lower reaction with water compared to aromatic polyisocyanates, making it easier to increase the molecular weight of polyurethane urea particles. In addition, using aliphatic polyisocyanates makes it easier to suppress discoloration of polyurethane urea particles due to light and heat.

[0049] Examples of chain-type aliphatic polyisocyanates include the chain-type aliphatic diisocyanates mentioned above, as well as adduct-type, biuret-type, and isocyanurate-type polyisocyanates of chain-type aliphatic diisocyanates such as PDI and HDI. Examples of cyclic aliphatic polyisocyanates include the cyclic aliphatic (alicyclic) diisocyanates mentioned above, as well as adduct-type, biuret-type, and isocyanurate-type polyisocyanates of cyclic aliphatic (alicyclic) diisocyanates such as IPDI.

[0050] The polyisocyanate content relative to the total mass of the reactive components is preferably 18% to 52% by mass, more preferably 20% to 48% by mass, and even more preferably 20% to 45% by mass. The polyisocyanate crosslinking agent content relative to the total mass of the reactive components is preferably 3% to 40% by mass, more preferably 4% to 35% by mass. The diisocyanate compound content relative to the total mass of the reactive components is preferably 3% to 40% by mass, more preferably 4% to 35% by mass. Furthermore, the ratio of the amount of polyisocyanate crosslinking agent to the total amount of polyisocyanate used as a reactive component is preferably 20% to 90% by mass, and more preferably 22% to 85% by mass.

[0051] Furthermore, the total content of the polyamine and polyisocyanate relative to the total mass of the reactive components is preferably 20% to 55% by mass, more preferably 22% to 53% by mass, and even more preferably 25% to 50% by mass. The polyurethane urea particles may also be reaction products of the reactive components consisting of a polyol, a polyamine, and a polyisocyanate.

[0052] (Crosslink density) The crosslinking density of polyurethane urea particles is the crosslinking density derived from the polyfunctional components in the reactive components that form the polyurethane urea particles, which have more than two functional groups. The polyfunctional components that cause crosslinking include the aforementioned polyisocyanate crosslinking agents with more than two functional groups. Furthermore, when low-molecular-weight polyols or polyamines with more than two functional groups are used as reactive components, these are also included in the polyfunctional components with more than two functional groups.

[0053] The crosslinking density of polyurethane urea particles is between 0.30 mol / kg and 0.80 mol / kg. If the crosslinking density of polyurethane urea particles is less than 0.30 mol / kg, the particle shape cannot be maintained, and for example, aggregation, fusion, or melting of particles may occur during drying, making it difficult to separate them as individual particles. Furthermore, films formed from coating agents prepared using such polyurethane urea particles have insufficient abrasion resistance and matte finish, as well as poor heat resistance and insufficient matte finish when heated. On the other hand, if the crosslinking density of polyurethane urea particles is greater than 0.80 mol / kg, films formed from coating agents prepared using such polyurethane urea particles have poor flexibility and soft feel at low temperatures.

[0054] From the viewpoint of improving the abrasion resistance, matte finish, and heat resistance of the above film, the crosslinking density of the polyurethane urea particles is preferably 0.31 mol / kg or more, and more preferably 0.32 mol / kg or more. Furthermore, from the viewpoint of improving the flexibility and soft feel of the above film at low temperatures, the crosslinking density of the polyurethane urea particles is preferably 0.75 mol / kg or less, and more preferably 0.60 mol / kg or less. Moreover, from the viewpoint of further improving the flexibility of the above film at low temperatures, the crosslinking density of the polyurethane urea particles is even more preferably 0.50 mol / kg or less, and particularly preferably 0.45 mol / kg or less.

[0055] The crosslinking density (mol / kg) of polyurethane urea particles represents the amount of polyfunctional components (mol) per unit mass (kg) of polyurethane urea particles. Therefore, the crosslinking density (mol / kg) of polyurethane urea particles can be determined by dividing the amount of polyfunctional components (mol) in the reactive components forming the polyurethane urea particles by the mass (kg) of the polyurethane urea particles. The mass of the polyurethane urea particles can be the total mass of the reactive components used in the polyurethane urea particles (polyols, polyamines, and polyisocyanates, as well as chain extenders that may be used as needed). The method for calculating the crosslinking density will be specifically explained below with reference to several examples of polyurethane urea particles in the examples described later.

[0056] The method for calculating the crosslinking density of polyurethane urea particles produced in Example 1, described later, is as follows. The only polyfunctional component with more than two functional groups used in the polyurethane urea particles of Example 1 is the polyisocyanate crosslinking agent (HDI isocyanurate-type polyisocyanate; trade name "Duranate® TKA-100", manufactured by Asahi Kasei Corporation; number of functional groups = 3, NCO% = 21.7% by mass, solid content = 100% by mass). The mass (g) of isocyanate groups (NCO) is calculated by multiplying the amount of polyisocyanate crosslinking agent used (g) by the isocyanate group content (NCO%), and the molar amount (mol) of NCO is calculated by dividing the mass (g) of NCO by the molecular weight of NCO (assuming 42). Next, the molar amount (mol) of the polyisocyanate crosslinking agent is calculated by dividing the molar amount (mol) of NCO by the number of functional groups of the polyisocyanate crosslinking agent (3). Then, the crosslinking density (mol / kg) is calculated by dividing the molar amount (mol) of the polyisocyanate crosslinking agent by the mass of polyurethane urea particles (total mass of reactive components; kg). The formula for calculating the crosslinking density of polyurethane urea particles in Example 1, calculated as described above, is shown below. [{(31.9×0.217)÷42}÷3]÷0.15470≒0.36mol / kg

[0057] Furthermore, the method for calculating the crosslinking density of the polyurethane urea particles produced in Example 4, described later, is as follows. The polyfunctional components with more than two functional groups used in the polyurethane urea particles of Example 4 are a polyisocyanate crosslinking agent (HDI isocyanurate-type polyisocyanate; trade name "Duranate® TKA-100", manufactured by Asahi Kasei Corporation; number of functional groups = 3, NCO% = 21.7% by mass, solids content = 100% by mass) and trimethylolpropane (hereinafter also referred to as "TMP"), which is a trifunctional polyol. In this case, the crosslinking density of the polyurethane urea particles can be calculated by {moles of polyisocyanate crosslinking agent (mol) + molars of TMP (mol)} ÷ mass of polyurethane urea particles (total mass of reactive components; kg). The calculation of the molar amount (mol) of the polyisocyanate crosslinking agent is as described in the method for calculating the crosslinking density of polyurethane urea particles in Example 1 above. Furthermore, the molar amount (mol) of TMP can be calculated by dividing the mass of TMP by the molecular weight of TMP (assuming 134.2). The formula for calculating the crosslinking density of polyurethane urea particles in Example 4 is shown below. [{(7.89×0.217÷42)÷3}+(4.025÷134.2)]÷0.13986≒0.31mol / kg

[0058] Furthermore, the method for calculating the crosslinking density of the polyurethane urea particles produced in Example 20, described later, is as follows. The polyfunctional components with more than two functional groups used in the polyurethane urea particles of Example 20 are a polyisocyanate crosslinking agent (HDI isocyanurate-type polyisocyanate; trade name "Duranate® TKA-100", manufactured by Asahi Kasei Corporation; number of functional groups = 3, NCO% = 21.7% by mass, solids content = 100% by mass) and diethylenetriamine (hereinafter also referred to as DETA), which is a trifunctional polyamine. In this case, the crosslinking density of the polyurethane urea particles can be calculated as {moles of polyisocyanate crosslinking agent (mol) + molars of DETA (mol)} ÷ mass of polyurethane urea particles (total mass of reactive components; kg). The calculation of the molar amount (mol) of the polyisocyanate crosslinking agent is as described in the method for calculating the crosslinking density of polyurethane urea particles in Example 1 above. Furthermore, the molar amount (mol) of DETA can be calculated by dividing the mass of DETA by the molecular weight of DETA (assuming 103.17). The formula for calculating the crosslinking density of polyurethane urea particles in Example 20 is shown below. {(8.708×0.217÷42÷3)+(2.94÷103.17)}÷0.13129≒0.33mol / kg

[0059] (Urea group content) The urea group content in polyurethane urea particles is between 0.50 mol / kg and 2.00 mol / kg. If the urea group content in polyurethane urea particles is less than 0.50 mol / kg, the film formed by the coating agent prepared using those polyurethane urea particles will have insufficient heat resistance and poor abrasion resistance. On the other hand, if the urea group content in polyurethane urea particles exceeds 2.00 mol / kg, the film formed by the coating agent prepared using those polyurethane urea particles will have poor flexibility and soft feel at low temperatures.

[0060] From the viewpoint of improving the heat resistance and abrasion resistance of the above film, the content of the urea group is preferably 0.52 mol / kg or more, and more preferably 0.55 mol / kg or more. Furthermore, from the viewpoint of improving the flexibility and soft feel of the above film at low temperatures, the content of the urea group is preferably 1.90 mol / kg or less, and more preferably 1.80 mol / kg or less.

[0061] The urea group content (mol / kg) in polyurethane urea particles represents the molar amount (mol) of urea groups per unit mass (kg) of polyurethane urea particles. Urea groups in polyurethane urea particles are formed by the reaction of amines with isocyanates. Since 1 mole of amine reacts with NCO to produce 1 mole of urea bonds, the urea group content can be calculated using the following formula. Content of urea groups in polyurethane urea particles = Molar amount of urea (mol) ÷ Mass of polyurethane urea particles (kg) = Molar amount of amine reacted (mol) ÷ Mass of polyurethane urea particles (kg)

[0062] The method for calculating the urea group content in the polyurethane urea particles produced in Example 1, described later, is as follows. The polyamine used in the polyurethane urea particles of Example 1 is hydrazine monohydrate (60% solids by mass). The molar amount (mol) of hydrazine is calculated by multiplying the mass (g) of hydrazine monohydrate by the solids content (% by mass) and dividing by the molecular weight of hydrazine monohydrate (assuming 50.06). Next, the molar amount (mol) of amino groups is calculated by multiplying the molar amount (mol) of hydrazine by the number of functional groups (2) of hydrazine monohydrate. Then, the urea group content (mol / kg) in the polyurethane urea particles is calculated by dividing the molar amount (mol) of amino groups by the mass of the polyurethane urea particles (total mass of reactive components; kg). The formula for calculating the urea group content in the polyurethane urea particles of Example 1, calculated as described above, is shown below. (8.071×0.6)÷50.06×2÷0.15470≒1.25mol / kg

[0063] (Volume-average particle size) The volume-average particle diameter of polyurethane urea particles is 1 μm or more and 30 μm or less. If the volume-average particle diameter of polyurethane urea particles is less than 1 μm, the film formed by the coating agent prepared using those polyurethane urea particles will have poor abrasion resistance, heat resistance, soft feel, and matte finish. On the other hand, if the volume-average particle diameter of polyurethane urea particles is greater than 30 μm, the polyurethane urea particles tend to settle, the storage stability of the coating agent prepared using those particles will be poor, and the soft feel and appearance of the formed film will also be poor. Preferably, the volume-average particle diameter of polyurethane urea particles is 2 μm or more and 25 μm or less, more preferably 2.5 μm or more and 20 μm or less, and even more preferably 3 μm or more and 15 μm or less. When the volume-average particle diameter of polyurethane urea particles is within the above preferred range, the storage stability of the coating agent is better, and the abrasion resistance, heat resistance, soft feel, matte finish, and appearance of the film formed by the coating agent tend to be better.

[0064] The volume-average particle diameter (MV) of polyurethane urea particles represents the average particle diameter weighted by volume. For a group of polyurethane urea particles being measured, if the particle diameter of a single particle is di and its volume is Vi, the volume-average particle diameter (MV) of the polyurethane urea particles can be calculated using the following equation (1). The volume-average particle diameter (MV) of polyurethane urea particles can be obtained using a particle size distribution analyzer that employs the laser diffraction / scattering method. MV=Σ(Vi·di) / Σ(Vi) ···(1)

[0065] (10% compressive strength) Polyurethane urea particles, having the specific crosslinking density described above, are spherical particles (beads) with a certain degree of hardness and strength, as shown in Figure 1. For example, if the crosslinking density is insufficient, such as less than 0.30 mol / kg, as mentioned earlier, aggregation, fusion, and melting of the particles will occur during drying, making it difficult to separate them as individual particles. Figure 1 is an image of an aggregate of polyurethane urea particles obtained by drying an aqueous dispersion of polyurethane urea particles used in Example 1, described later, when observed with a scanning electron microscope (SEM).

[0066] The 10% compressive strength of polyurethane urea particles at 25°C is preferably 0.1 MPa to 1.4 MPa, and more preferably 0.1 MPa to 1.3 MPa. When the 10% compressive strength of polyurethane urea particles is 0.1 MPa or higher, the coating agent prepared using these polyurethane urea particles tends to form a film with better abrasion resistance. From this viewpoint, the 10% compressive strength of polyurethane urea particles is even more preferably 0.2 MPa or higher. On the other hand, when the 10% compressive strength of polyurethane urea particles is 1.4 MPa or lower, the coating agent prepared using these polyurethane urea particles tends to form a film with better flexural resistance and soft feel at low temperatures. From this viewpoint, the 10% compressive strength of polyurethane urea particles is even more preferably 1.2 MPa or lower.

[0067] The 10% compressive strength of polyurethane urea particles can be measured at 25°C using a microcompression tester. This measurement is performed by applying a load to a single polyurethane urea particle set on a sample stage using a circular flat plate indenter with a diameter of 50 μm at a constant loading rate, and measuring the load value (mN) and the displacement amount (μm) at which the compressive displacement reaches 10% of the volume-average particle diameter. Measurements can be performed on 10 polyurethane urea particles, and the average value can be used as the measured value.

[0068] (Method for manufacturing polyurethane urea particles) The method for producing polyurethane urea particles described above is not particularly limited and can be carried out by following known manufacturing methods. A preferred method for producing polyurethane urea particles will be described below.

[0069] In one embodiment, a method for producing polyurethane urea particles preferably includes the steps of reacting a polyol and a polyisocyanate to obtain a urethane-based prepolymer having isocyanate groups at its terminals, and reacting the obtained urethane-based prepolymer with a polyamine to obtain polyurethane urea particles.

[0070] In the process of obtaining a urethane-based prepolymer, for example, the polyol and polyisocyanate can be reacted first in the presence or absence of an organic solvent that does not contain active hydrogen in its molecule. In the process of obtaining a urethane-based prepolymer, it is preferable to prepare a suspension by mixing a raw material solution containing the polyol, polyisocyanate, and an organic solvent that does not contain active hydrogen in its molecule with an aqueous medium and carrying out the reaction under stirring. The reaction in this step can be continued until the product is, for example, theoretically NCO%, to obtain a urethane-based prepolymer having isocyanate groups at the ends. Specifically, the reaction should be carried out at a ratio such that the molar ratio of isocyanate groups (NCO groups) in the polyisocyanate to hydroxyl groups (OH groups) in the polyol is 1.1 to 10, preferably [NCO groups / OH groups (molar ratio)] = 1.2 to 5.0. The temperature conditions in this step are not particularly limited, but for example, 20°C to 150°C is preferred, and 30°C to 110°C is more preferred.

[0071] Examples of organic solvents include ketone solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, ether solvents, ester solvents, glycol ether ester solvents, amide solvents, and lactam solvents. Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of aromatic hydrocarbon solvents include toluene and xylene. Examples of aliphatic hydrocarbon solvents include n-hexane. Examples of ether solvents include dioxane, dimethyl ether, diethyl ether, dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and tetrahydrofuran. Examples of ester solvents include ethyl acetate, butyl acetate, and isobutyl acetate. Examples of glycol ether ester solvents include ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, and ethyl-3-ethoxypropionate. Examples of amide solvents include dimethylformamide and dimethylacetamide. Examples of lactam solvents include N-methyl-2-pyrrolidone. One or more of the organic solvents listed above can be used.

[0072] When preparing a suspension by mixing the above-mentioned raw material solution with the aqueous medium, at least water should be used. To stably disperse the raw material solution in the aqueous medium, it is preferable to include a surfactant in the aqueous medium, that is, to use an aqueous medium containing water and a surfactant. Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. The surfactant may be a combination of two or more surfactants.

[0073] Examples of anionic surfactants include carboxylic acids or their salts, sulfate esters, carboxymethyl salts, sulfonates, and phosphate esters.

[0074] Examples of carboxylic acids or their salts include saturated or unsaturated fatty acids having 8 to 22 carbon atoms, or their salts. Examples of salts include sodium, potassium, ammonium, and alkanolamine salts thereof.

[0075] Examples of sulfate esters include higher alcohol sulfate esters (sulfate esters of aliphatic alcohols with 8 to 18 carbon atoms), higher alkyl ether sulfate esters (sulfate esters of ethylene oxide adducts of aliphatic alcohols with 8 to 18 carbon atoms), sulfated oils (natural unsaturated oils or unsaturated waxes that have been sulfated and neutralized), sulfated fatty acid esters (lower alcohol esters of unsaturated fatty acids that have been sulfated and neutralized), and sulfated olefins (olefins with 12 to 18 carbon atoms that have been sulfated and neutralized). Examples of salts include sodium salts, potassium salts, ammonium salts, and alkanolamine salts. Specific examples of higher alcohol sulfate esters include octyl alcohol sulfate, decyl alcohol sulfate, lauryl alcohol sulfate, and stearyl alcohol sulfate.

[0076] Examples of carboxymethylated salts include carboxymethylated salts of aliphatic alcohols having 8 to 16 carbon atoms and carboxymethylated salts of 1 to 10 molar ethylene oxide adducts of aliphatic alcohols having 8 to 16 carbon atoms. Specific examples of carboxymethylated salts of aliphatic alcohols include octyl alcohol carboxymethylated sodium salt, decyl alcohol carboxymethylated sodium salt, lauryl alcohol carboxymethylated sodium salt, dovanol-23 carboxymethylated sodium salt, and tridecanol carboxymethylated sodium salt. Specific examples of carboxymethylated salts of 1 to 10 molar ethylene oxide adducts of aliphatic alcohols include octyl alcohol ethylene oxide 3 molar adduct carboxymethylated sodium salt, lauryl alcohol ethylene oxide 4 molar adduct carboxymethylated sodium salt, dovanol-23 ethylene oxide 3 molar adduct carboxymethylated sodium salt, and tridecanol ethylene oxide 5 molar adduct carboxymethylated sodium salt.

[0077] Examples of sulfonates include alkylbenzene sulfonates, alkylnaphthalene sulfonates, sulfosuccinate diesters, α-olefin sulfonates, Igepon T-type, and sulfonates of other aromatic ring-containing compounds. Specific examples of alkylbenzene sulfonates include sodium dodecylbenzenesulfonate; specific examples of alkylnaphthalene sulfonates include sodium dodecylnaphthalenesulfonate; and specific examples of sulfosuccinate diesters include sodium di-2-ethylhexyl sulfosuccinate. Examples of sulfonates of aromatic ring-containing compounds include mono- or disulfonates of alkylated diphenyl ethers and styrene-phenol sulfonates.

[0078] Examples of phosphate ester salts include higher alcohol phosphate ester salts and higher alcohol ethylene oxide adduct phosphate ester salts. Specific examples of higher alcohol phosphate ester salts include lauryl alcohol phosphate monoester disodium salt and lauryl alcohol phosphate diester sodium salt; a specific example of higher alcohol ethylene oxide adduct phosphate ester salts is oleyl alcohol ethylene oxide 5-mol adduct phosphate monoester disodium salt.

[0079] Examples of cationic surfactants include quaternary ammonium salts and amine salts.

[0080] Quaternary ammonium salts are obtained by the reaction of tertiary amines with quaternizing agents (alkylating agents such as methyl chloride, methyl bromide, ethyl chloride, benzyl chloride, and dimethyl sulfate; ethylene oxide, etc.). Examples include lauryltrimethylammonium chloride, didecyldimethylammonium chloride, dioctyldimethylammonium bromide, stearyltrimethylammonium bromide, lauryldimethylbenzylammonium chloride (benzalkonium chloride), cetylpyridinium chloride, polyoxyethylenetrimethylammonium chloride, and stearamidoethyldiethylmethylammonium methosulfate.

[0081] Amine salts are obtained by neutralizing primary to tertiary amines with inorganic acids (such as hydrochloric acid, nitric acid, sulfuric acid, and hydroiodic acid) or organic acids (such as acetic acid, formic acid, oxalic acid, lactic acid, gluconic acid, adipic acid, and alkyl phosphate). For example, primary amine salts include inorganic or organic salts of aliphatic higher amines (such as laurylamine, stearylamine, cetylamine, hardened beef tallowamine, and rosinamine); and salts of lower amines with higher fatty acids (such as stearic acid and oleic acid). Secondary amine salts include, for example, inorganic or organic salts of ethylene oxide adducts of aliphatic amines. Examples of tertiary amine salts include inorganic or organic salts of aliphatic amines (triethylamine, ethyldimethylamine, N,N,N',N'-tetramethylethylenediamine, etc.), ethylene oxide (2 moles or more) adducts of aliphatic amines, alicyclic amines (N-methylpyrrolidine, N-methylpiperidine, N-methylhexamethyleneimine, N-methylmorpholine, 1,8-diazabicyclo(5,4,0)-7-undecene, etc.), nitrogen-containing heterocyclic aromatic amines (4-dimethylaminopyridine, N-methylimidazole, 4,4'-dipyridyl, etc.); and inorganic or organic salts of tertiary amines such as triethanolamine monostearate and stearamidoethyldiethylmethylethanolamine.

[0082] Examples of amphoteric surfactants include carboxylate-type amphoteric surfactants, sulfate-type amphoteric surfactants, sulfonate-type amphoteric surfactants, and phosphate-type amphoteric surfactants. Carboxylate-type amphoteric surfactants can be further divided into amino acid-type amphoteric surfactants and betaine-type amphoteric surfactants.

[0083] Examples of nonionic surfactants include alkylene oxide-added nonionic surfactants and polyhydric alcohol-type nonionic surfactants.

[0084] Alkylene oxide-additive nonionic surfactants can be obtained by directly adding an alkylene oxide to a higher alcohol, a higher fatty acid, or an alkylamine, or by reacting polyalkylene glycols obtained by adding an alkylene oxide to glycols with a higher fatty acid, or by adding an alkylene oxide to an ester product obtained by reacting a polyhydric alcohol with a higher fatty acid, or by adding an alkylene oxide to a higher fatty acid amide. Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide. Of these, ethylene oxide and random or blocked adducts of ethylene oxide and propylene oxide are preferred.

[0085] Specific examples of alkylene oxide-added nonionic surfactants include oxyalkylene alkyl ethers (e.g., octyl alcohol ethylene oxide adduct, lauryl alcohol ethylene oxide adduct, stearyl alcohol ethylene oxide adduct, oleyl alcohol ethylene oxide adduct, lauryl alcohol ethylene oxide propylene oxide block adduct, etc.); polyoxyalkylene higher fatty acid esters (e.g., stearyl ethylene oxide adduct, lauryl ethylene oxide adduct, etc.); polyoxyalkylene polyhydric alcohol higher fatty acid esters (e.g., polyethylene glycol laurate diester, polyethylene glycol oleate diester, polyethylene glycol stearate diester, etc.); polyoxyalkylene Examples include hydroxyphenyl ethers (e.g., nonylphenol ethylene oxide adduct, nonylphenol ethylene oxide propylene oxide block adduct, octylphenol ethylene oxide adduct, bisphenol A ethylene oxide adduct, dinonylphenol ethylene oxide adduct, styrene-phenol ethylene oxide adduct, etc.); polyoxyalkylene alkylamino ethers (e.g., laurylamine ethylene oxide adduct, stearylamine ethylene oxide adduct, etc.); and polyoxyalkylene alkyl alkanolamides (e.g., ethylene oxide adduct of hydroxyethyl laurate amide, ethylene oxide adduct of hydroxypropyl oleamide, ethylene oxide adduct of dihydroxyethyl laurate amide, etc.).

[0086] Examples of polyhydric alcohol-type nonionic surfactants include polyhydric alcohol fatty acid esters, polyhydric alcohol fatty acid ester alkylene oxide adducts, polyhydric alcohol alkyl ethers, and polyhydric alcohol alkyl ether alkylene oxide adducts.

[0087] Specific examples of polyhydric alcohol fatty acid esters include pentaerythritol monolaurate, pentaerythritol monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan monolaurate, sorbitan dilaurate, sorbitan dioleate, and sucrose monostearate. Specific examples of polyhydric alcohol fatty acid ester alkylene oxide adducts include ethylene glycol monooleate ethylene oxide adduct, ethylene glycol monostearate ethylene oxide adduct, trimethylolpropane monostearate ethylene oxide propylene oxide random adduct, sorbitan monolaurate ethylene oxide adduct, sorbitan monostearate ethylene oxide adduct, sorbitan distearate ethylene oxide adduct, and sorbitan dilaurate ethylene oxide propylene oxide random adduct. Specific examples of polyhydric alcohol alkyl ethers include pentaerythritol monobutyl ether, pentaerythritol monolauryl ether, sorbitan monomethyl ether, sorbitan monostearyl ether, methyl glycoside, and lauryl glycoside. Specific examples of polyhydric alcohol alkyl ether alkylene oxide adducts include sorbitan monostearyl ether ethylene oxide adduct, methyl glycoside ethylene oxide propylene oxide random adduct, lauryl glycoside ethylene oxide adduct, and stearyl glycoside ethylene oxide propylene oxide random adduct.

[0088] For the purpose of ensuring the stability of the suspension during synthesis and preventing particle aggregation, anionic or nonionic surfactants are preferred, and alkylbenzene sulfonates or alkylene oxide-added nonionic surfactants are more preferred. The amount of surfactant used is preferably 0.1% to 20% by mass, and more preferably 1% to 10% by mass, relative to the total mass of the reactive components.

[0089] In the process of obtaining a urethane-based prepolymer, if a diol compound having an acidic group is used as the polyol, the process may include a step of neutralizing the acidic group in the urethane-based prepolymer with a neutralizing agent before reacting the polyamine with the urethane-based prepolymer. Examples of neutralizing agents include organic amines such as trimethylamine, triethylamine, triisopropylamine, and tributylamine; inorganic alkali salts such as sodium hydroxide and potassium hydroxide; and ammonia.

[0090] In the process of obtaining polyurethane urea particles, a urethane-based prepolymer and a polyamine are mixed, and the urethane-based prepolymer undergoes a chain extension reaction to generate urea bonds, thereby obtaining polyurethane urea particles. Subsequently, by removing the organic solvent used as needed, an aqueous dispersion of polyurethane urea particles can be obtained. Depending on the application and desired usage, dried bead-shaped polyurethane urea particles can also be obtained by drying the obtained aqueous dispersion of polyurethane urea particles.

[0091] In addition, catalysts may be used as needed in the synthesis of polyurethane urea. Examples of catalysts include salts of metals with organic and inorganic acids, such as dibutyltin laurate, dioctyltin laurate, stanus octoate, lead octoate, and tetra-n-butyl titanate, as well as organometallic derivatives; organic amines such as triethylamine; and diazabicycloundecene catalysts.

[0092] Furthermore, if isocyanate groups remain at the polymer ends after the synthesis of polyurethane urea, a reaction termination agent may be added to terminate the isocyanate ends. Examples of reaction termination agents include monoalcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and tert-butyl alcohol; monoamines such as monoethylamine, n-propylamine, diethylamine, di-n-propylamine, and di-n-butylamine; and alkanolamines such as monoethanolamine, diethanolamine, mono-n-butylethanolamine, N-methylethanolamine, N-ethylaminoethanol, N-tert-butylethanolamine, adrenaline, 2-(4-aminophenyl)ethyl alcohol, trishydroxymethylaminomethane, 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 3-amino-1,2-propanediol, 2-amino-1-butanol, 1-amino-2-butanol, and 5-amino-1-pentanol.

[0093] <Aqueous dispersion of polyurethane urea particles> Polyurethane urea particles may be in powder form or dispersed in an aqueous medium. Both forms of polyurethane urea particles can be used directly in the preparation of the coating agent described later. In particular, it is preferable to use polyurethane urea particles dispersed in an aqueous medium, i.e., an aqueous dispersion of polyurethane urea particles containing an aqueous medium and the polyurethane urea particles dispersed in the aqueous medium. As described above, an aqueous dispersion of polyurethane urea particles can be obtained by a preferred method for producing polyurethane urea particles. Therefore, if the aqueous dispersion of polyurethane urea particles is used directly in the preparation of the coating agent, drying steps to separate the polyurethane urea particles from the aqueous dispersion become unnecessary, resulting in advantages such as a reduction in the number of steps and a reduction in the energy required for drying.

[0094] The content of polyurethane urea particles in an aqueous dispersion of polyurethane urea particles is preferably 5% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 50% by mass or less, based on the total mass of the aqueous dispersion.

[0095] <Coating agent> A coating agent can be obtained by using the polyurethane urea particles described above. That is, the aqueous coating agent of one embodiment of the present invention contains the polyurethane urea particles described above. Because this coating agent contains the polyurethane urea particles described above, it is possible to form a film with a matte appearance that has good abrasion resistance, flexibility at low temperatures, heat resistance that does not easily impair the matte appearance even after heating, and a soft feel.

[0096] The content of polyurethane urea particles is preferably 0.01% to 90% by mass, and more preferably 0.1% to 70% by mass, based on the total solid content in the coating agent. Furthermore, the content of polyurethane urea particles is preferably 0.01% to 50% by mass, and more preferably 0.02% to 40% by mass, based on the total mass of the coating agent. In addition, the content of solid content in the coating agent can be appropriately determined according to the application of the coating agent, and is usually around 1% to 95% by mass, preferably 5% to 60% by mass, and more preferably 10% to 50% by mass.

[0097] The aqueous coating agent contains the polyurethane urea particles described above, as well as an aqueous medium, and may further contain a binder resin, a curing agent, and various additives as needed. The coating agent preferably contains at least a binder resin in addition to the polyurethane urea particles described above, and more preferably contains polyurethane urea particles, an aqueous medium, a binder resin, and a curing agent.

[0098] When preparing the coating agent, it is preferable to use the aqueous dispersion of polyurethane urea particles described above. More preferably, the coating agent is prepared by mixing the aqueous dispersion of polyurethane urea particles, a binder resin, and, if necessary, further aqueous media, a curing agent, and various additives. The curing agent may be added at the time of use of the coating agent. Various dispersion devices may be used when mixing the components to prepare the coating agent. Examples of dispersion devices include dispersers, homogenizers, and paint shakers.

[0099] Examples of binder resins include polyurethane resins, acrylic resins, silicone resins, amide resins, vinyl chloride-vinyl acetate copolymers, and cellulose resins. One or more of these binder resins can be used. It is preferable to use an aqueous polyurethane resin as the binder resin.

[0100] The binder resin content in the coating agent is preferably 5% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 40% by mass or less, based on the solid content in the coating agent. The binder resin content in the coating agent is preferably 0.05 times or more and 3 times or less by mass relative to the content of the polyurethane urea particles mentioned above.

[0101] Examples of curing agents include isocyanate-based curing agents, carbodiimide-based curing agents, oxazoline-based curing agents, and epoxy-based curing agents. One or more of these curing agents can be used. Among these, it is preferable to use at least one curing agent selected from the group consisting of isocyanate-based curing agents and carbodiimide-based curing agents.

[0102] The amount of curing agent in the coating agent is preferably 0.5 parts by mass or more and 20 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total amount of polyurethane urea particles and binder resin in the coating agent.

[0103] Examples of additives include, for example, design-enhancing agents such as organic and inorganic fine particles other than the aforementioned polyurethane urea particles, as well as antioxidants, light stabilizers, ultraviolet absorbers, gas discoloration stabilizers, metal deactivators, pigments, dyes, antifungal agents, flame retardants, lubricants, slip agents, leveling agents, thickeners, defoamers, dispersants, emulsifiers, and surfactants. One or more of these additives can be used.

[0104] The coating agent can be any material that is applied to the surface of a substrate. Water-based coating agents include, for example, water-based paints, inks, surface treatment agents, adhesives, and tacks. Among these, paints and surface treatment agents are preferred, and more preferably are paints and surface treatment agents used for synthetic imitation leather.

[0105] The base material is not particularly limited and can include, in addition to synthetic imitation leather, plastics, paper, wood, fabrics, metals (e.g., iron, aluminum, copper, and stainless steel), and non-metallic inorganic materials (e.g., glass, ceramics, hardened cement compositions, and hardened gypsum compositions). Examples of plastic material types include polyolefin resins such as polyethylene resins and polypropylene resins; polyamide resins such as nylon 6, nylon 66, and nylon 12; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polylactic acid; unsaturated polyester resins; polyvinyl chloride resins; polyurethane resins; polystyrene resins; acrylic resins; polycarbonate resins; ethylene-vinyl acetate copolymers; ABS resins; polyolefin thermoplastic elastomers; and the like. Examples of plastic base materials include films, sheets, and various molded articles. Synthetic imitation leather is preferred as the base material, and the surface material constituting the synthetic imitation leather is more preferred.

[0106] Examples of coating methods include spray coating, gravure coating, roll coating, air knife coating, bar coating, die coating, curtain coating, and immersion coating. The thickness of the film after coating and drying is preferably 1 μm to 50 μm, and more preferably 5 μm to 25 μm. The drying temperature after coating is preferably 50°C to 150°C, and the drying time is preferably 1 minute to 10 minutes.

[0107] The aqueous coating agent containing polyurethane urea particles, as detailed above, can form a matte-finish film with good abrasion resistance, flexibility at low temperatures, heat resistance, and a soft feel. Therefore, the aqueous coating agent is more useful as a surface treatment agent or paint for synthetic imitation leather, for example. This synthetic imitation leather is suitable as a material for shoes, clothing, bags, furniture, headphones, and vehicle interior materials (e.g., instrument panels, doors, consoles, and seats).

[0108] As mentioned above, one embodiment of the present invention can have the following configuration. [1] Polyurethane urea particles which are reaction products of reactive components including polyols, polyamines, and polyisocyanates, The polyisocyanate comprises a polyisocyanate crosslinking agent having more than 2 functional groups. The crosslinking density derived from polyfunctional components in the reactive component having more than 2 functional groups is 0.30 mol / kg or more and 0.80 mol / kg or less. The urea group content in the polyurethane urea particles is 0.50 mol / kg or more and 2.00 mol / kg or less. Polyurethane urea particles having a volume-average particle diameter of 1 μm or more and 30 μm or less. [2] The polyurethane urea particle according to [1] above, wherein the polyol comprises at least one polymer polyol selected from the group consisting of polyether polyols and polycarbonate polyols. [3] The polyurethane urea particles according to [2] above, wherein the content of the polymer polyol relative to the total mass of the reactive component is 45% by mass or more and 80% by mass or less. [4] The polyurethane urea particle according to any one of [1] to [3] above, wherein the polyisocyanate comprises at least one aliphatic polyisocyanate selected from the group consisting of chain-type aliphatic polyisocyanates and cyclic aliphatic polyisocyanates. [5] Polyurethane urea particles as described in any of [1] to [4] above, wherein the 10% compressive strength at 25°C is 0.1 MPa or more and 1.4 MPa or less. [6] An aqueous medium, and an aqueous dispersion of polyurethane urea particles containing polyurethane urea particles according to any one of [1] to [5] above dispersed in the aqueous medium. [7] An aqueous coating agent containing polyurethane urea particles as described in any of [1] to [5] above. [8] The water-based coating agent described above in [7] for use with synthetic imitation leather. [Examples]

[0109] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0110] <Preparing the polyol> (Polymer polyol) As polymeric polyols, we prepared polyether polyols 1-2 and polycarbonate polyols 1-5 as shown in Table 1 below. All of the polymeric polyols shown in Table 1 are polyols (polymeric diols) with two functional groups. Hereafter, polyether polyols may be referred to as "PEPO" and polycarbonate polyols as "PCPO".

[0111] TIFF0007856825000001.tif87170

[0112] (Low molecular weight polyols) The following low-molecular-weight polyols were prepared. All of them were used as chain elongators. • Dimethylolpropionic acid (BisMPA; molecular weight 134.12, number of functional groups 2) • 1,4-Butanediol (molecular weight 90.1, number of functional groups 2) • Neopentyl glycol (molecular weight 104.15, number of functional groups 2) • 3-methyl-1,5-pentanediol (molecular weight 118.18, number of functional groups 2) Trimethylolpropane (molecular weight 134.2, number of functional groups 3)

[0113] <Preparation of polyamines> The following polyamines were prepared. All of them were used as chain extenders. ·Hydrazine monohydrate (solid content 60% by mass, molecular weight 50.06, number of functional groups 2) • 1,3-Bis(aminomethyl)cyclohexane (molecular weight 142.24, number of functional groups 2) • Diethylenetriamine (molecular weight 103.17, number of functional groups 3)

[0114] <Preparing polyisocyanates> (Polyisocyanate crosslinking agent) As polyisocyanate crosslinking agents, we prepared polyisocyanate crosslinking agents 1 to 5, as shown in Table 2 below. In calculating the crosslinking density described later, we assumed that the number of functional groups for polyisocyanate crosslinking agents 1 to 5 was 3, based on the representative structural formulas listed in the product catalogs and manufacturer websites of the polyisocyanate crosslinking agents, and calculated the crosslinking density. Hereafter, polyisocyanate crosslinking agents with more than 2 functional groups may be referred to as "NCO crosslinking agents".

[0115] TIFF0007856825000002.tif70170

[0116] (Diisocyanate compounds) The following diisocyanate compounds were prepared. • Isophorone diisocyanate (IPDI; molecular weight 222) • Hexamethylene diisocyanate (HDI; molecular weight 168) • Pentamethylene diisocyanate (PDI; molecular weight 154.17) · 4,4'-Methylenebiscyclohexyl diisocyanate (hydrogenated MDI; molecular weight 262)

[0117] <Manufacturing of polyurethane urea particles> (Example 1) A raw material solution was prepared by mixing 100.0 g of PEPO1 as a polyol, 19.7 g of hydrogenated MDI as a polyisocyanate, 31.9 g of NCO crosslinking agent 1, and methyl ethyl ketone (MEK) as a diluent at room temperature (25°C). The amount of MEK used was such that the solid content in the mixture (raw material solution) was 60% by mass.

[0118] In a reaction vessel equipped with a stirrer, thermometer, gas inlet tube, and reflux condenser, 7.74 g of sodium dodecylbenzenesulfonate (SDBS) as an anionic surfactant and 384.23 g of water were added and thoroughly mixed to dissolve, preparing an aqueous medium. While stirring the aqueous medium in the reaction vessel at 500 rpm, the above raw material solution was added to the aqueous medium to prepare a suspension. The temperature was raised to 60°C under continuous stirring, and the raw materials were reacted. After confirming that the isocyanate group content reached the desired level, the liquid in the reaction vessel was cooled to room temperature (25°C). Next, 8.071 g of hydrazine monohydrate (60% solids by mass) as a polyamine was added to the reaction vessel and reacted, and a peak (2260 cm²) derived from the isocyanate group was observed using a Fourier transform infrared spectrophotometer (FT-IR; trade name "FT-720", manufactured by Horiba, Ltd.). -1 It was confirmed that the surrounding area had disappeared. Subsequently, MEK was removed by vacuum degassing to obtain an aqueous dispersion of polyurethane urea particles (solid content 30% by mass) of Example 1.

[0119] (Examples 2-31, Comparative Examples 1-5) The types and amounts (in g) of polyol, polyisocyanate, and polyamine used in the production of polyurethane urea particles in Example 1, as well as the amount of SDBS (in g), were changed as shown in Table 3 (Tables 3-1 to 3-5). Otherwise, aqueous dispersions of polyurethane urea particles for Examples 2 to 31 and Comparative Examples 1 to 5 were obtained in accordance with the production method of Example 1. In Example 31, dimethylolpropionic acid (BisMPA) was neutralized with triethylamine (TEA) and emulsified. Since TEA volatilizes during drying, it is not included in the calculation of the resin component when calculating the crosslinking density, etc.

[0120] TIFF0007856825000003.tif166170

[0121] TIFF0007856825000004.tif166170

[0122] TIFF0007856825000005.tif167170

[0123] TIFF0007856825000006.tif166170

[0124] TIFF0007856825000007.tif167170

[0125] <Calculation of crosslinking density and urea group content> Using the calculation method described above, the crosslinking density (mol / kg) of each polyurethane urea particle, i.e., the molar amount (mol) of polyfunctional components per unit mass (kg) of each polyurethane urea particle, was calculated. Furthermore, using the calculation method described above, the urea group content (mol / kg) in each polyurethane urea particle, i.e., the molar amount (mol) of urea groups per unit mass (kg) of the polyurethane urea particle, was calculated. The mass of the polyurethane urea particles used in calculating the crosslinking density and urea group content was the total mass of the reactive components (polyol, polyamine, and polyisocyanate) used in the polyurethane urea particles.

[0126] <Measurement of volume-average particle diameter> The volume-average particle size of each polyurethane urea particle was measured. Specifically, an appropriate amount of aqueous dispersion of polyurethane urea particles was taken and adjusted to a solid content concentration suitable for measurement to prepare the sample. The volume-average particle size of each polyurethane urea particle was measured using this sample and a laser diffraction / scattering particle size distribution analyzer (product name "MT3300II", manufactured by Microtrac-Bell).

[0127] <Measurement of 10% compressive strength> The 10% compressive strength of each polyurethane urea particle was measured. The 10% compressive strength is the stress (MPa) required to crush a polyurethane urea particle by 10%, and a smaller value indicates softer material. Specifically, an appropriate amount of an aqueous dispersion of polyurethane urea particles was taken and dried to obtain the polyurethane urea particles used as samples. For these polyurethane urea particle samples, the compressive strength (MPa) of a single polyurethane urea particle at 10% deformation was measured using a microcompression tester (product name "MCT-500", manufactured by Shimadzu Corporation) under the following test conditions. Measurements were performed on 10 different particles for each polyurethane urea particle, and the average value was used as the measured value. Figure 1 shows the scanning electron microscope (SEM) images of the polyurethane urea particle samples from Example 1. (Test conditions) • Test temperature: 25℃ • Indenter type: FLAT50 Objective lens magnification: 50 ·Load speed: 0.0089mN / sec • Test load: 1mN

[0128] <Manufacturing of paints and preparation of test sheets> For each aqueous dispersion of polyurethane urea particles, aqueous paints and test sheets were prepared as described below. First, the aqueous dispersion of polyurethane urea particles and a polyurethane aqueous dispersion having film-forming ability as a binder resin (solid content 30% by mass; trade name "Rezamin D-6300", manufactured by Dainichi Seika Kogyo Co., Ltd.) were mixed in an amount such that the mass ratio of the solid content was polyurethane urea particles:polyurethane = 1:1. An appropriate amount of deionized water was added to this mixture to adjust the solid content of the mixture to 20% by mass. To 100 parts by mass of this 20% by mass mixture, 2 parts by mass of an isocyanate-based curing agent (trade name "Duranate WT30-100", manufactured by Asahi Kasei Corporation) was added to prepare an aqueous paint. Using a bar coater, a water-based paint was applied to a black polyvinyl chloride (PVC) sheet suitable for synthetic imitation leather, with a thickness of 50 μm, which served as the base material. The sheet was then dried in a dryer at 120°C for 1 minute to obtain a test sheet with a 10 μm thick film.

[0129] <Rating> The following evaluations were performed using the aqueous paints or test sheets of each example and comparative example. In the evaluation criteria shown below, "AAA", "AA", "A", and "B" were judged as acceptable results, and "C" and "D" were judged as unacceptable results. The results of each evaluation are shown in Table 4 (Tables 4-1 to 4-5). The "Polymer Polyol Content (mass%)" shown in Table 4 represents the content (mass%) of polymer polyol relative to the total mass of reactive components used in the production of polyurethane urea particles.

[0130] (Abrasion resistance) A test piece measuring 70 mm in width and 300 mm in length was cut from the test sheet. The test piece was placed on a cushioning material on the flat abrasion table of a JASO (Japan Automotive Engineering Society standard) M403 / 88 / Flat surface abrasion tester for fabric materials for seat surfaces (Method B, manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), and secured with clamps to prevent wrinkles. A friction element fitted with JIS L 3102 (cotton canvas) No. 6 cotton canvas was brought into contact with the test piece. An abrasion test was conducted with a pressing load including the friction element of 9.81 N (1 kgf), a stroke of 140 mm, and a speed of 60 ± 10 reciprocations / min for 10,000 reciprocations. The abrasion resistance of the coating was evaluated according to the evaluation criteria shown below. AAA (Excellent): No change in appearance. AA (Good): No scratches, only slight cosmetic changes. A (Normal): No scratches, but no obvious cosmetic changes. B (Acceptable): One or fewer visible scratches. C (Bad): Two to five visible scratches. D (Very Poor): Five or more visible scratches.

[0131] (cold resistance and flexibility) A test specimen measuring 50 mm in width and 150 mm in length was cut from the test sheet. Using a Dematcher bending tester, a bending test was performed under conditions of a bending stroke of 100 mm and -10°C, and the bending resistance of the coating at low temperatures (cold bending resistance) was evaluated according to the evaluation criteria shown below. AAA (Excellent): No whitening or cracking occurs after 30,000 uses. AA (Good): Whitening or cracking occurs between 20,000 and 30,000 cycles. A (Normal): Whitening or cracking occurs after 15,000 to less than 20,000 cycles. B (Acceptable): Whitening or cracking occurs after 10,000 to less than 15,000 cycles. C (Poor): Whitening or cracking occurs between 5,000 and 10,000 cycles. D (Very Poor): Whitening or cracking occurs in less than 5000 cycles.

[0132] (Matte finish) For the test sheets, the gloss value (60° incident light / 60° reflected light) was measured using a direct-reading haze computer (product name "HGM-2DP", manufactured by Suga Test Instruments Co., Ltd.), and the matte appearance of the coating was evaluated according to the evaluation criteria shown below. AA (Good): Gross value is less than 0.5. A (Normal): Gross value is 0.5 or higher and less than 1.0. C (Poor): Gross score is between 1.0 and 1.5. D (Very Bad): Gross score is 1.5 or higher.

[0133] (Matte appearance after heating) The gloss value of the film surface after heating the test sheet at 200°C for 3 minutes was measured in the same manner as described above, and the matte appearance of the film after heating was evaluated according to the evaluation criteria shown below. AA (Good): Gross value is less than 1.0. A (Normal): Gross value is 1.0 or higher and less than 1.5. C (Poor): Gross score is between 1.5 and 2.0. D (Very Bad): Gross score is 2.0 or higher.

[0134] (Change in matte finish before and after heating) The difference between the gloss value before heating and the gloss value before heating (the difference in gloss values) was calculated, and the change in the matte appearance before and after heating was evaluated according to the evaluation criteria shown below. AA (Good): The difference in gross values ​​is less than 0.3. A (Normal): The difference in gross values ​​is between 0.3 and 1.0. B (Acceptable): The difference in gross values ​​is between 1.0 and 1.5. C (Poor): The difference in gross values ​​is between 1.5 and 2.0. D (Very Bad): The difference in gross values ​​is 2.0 or more.

[0135] (Soft feel) The soft-feel properties of the coating were evaluated based on the tactile sensation obtained by touching the surface of the test sheet with a finger, according to the evaluation criteria below. The soft-feel properties of the coating were evaluated by 10 panelists. Each panelist assigned a score to the tactile sensation of the coating based on the evaluation criteria below, and the average score was used as the evaluation result for soft-feel properties. AAA: Elastic and has a very moist and pleasant texture. AA: Elastic and has a moist, pleasant texture. A: It has elasticity and a moist texture. B: It has a slightly moist texture. C: Lacking elasticity, it has a slippery, smooth, or dry texture. D: Lacking elasticity, it is very slippery and has a smooth or rough texture.

[0136] (Storage stability) After allowing each water-based paint to stand at 23°C for one month, the degree of sedimentation and aggregation of components in the water-based paint was visually observed, and the storage stability of the water-based paint was evaluated according to the evaluation criteria shown below. A: No sedimentation or aggregation is observed. B: Slight sedimentation or aggregation is observed. C: Sedimentation or aggregation is observed.

[0137] (exterior) The appearance of the coating was evaluated according to the following evaluation criteria by visually observing the surface of the test sheet and checking for the presence or absence of blurred white areas. A: It has a jet-black appearance based on the black color of the base material, with no blurry or whitish areas. B: Slightly blurred white areas can be observed. C: It has a pale, blurry appearance and lacks the deep black color that comes from the black base material.

[0138] TIFF0007856825000008.tif93170

[0139] TIFF0007856825000009.tif93170

[0140] TIFF0007856825000010.tif94170

[0141] TIFF0007856825000011.tif94170

[0142] TIFF0007856825000012.tif94170

Claims

1. An aqueous coating agent containing polyurethane urea particles, which are reaction products of reactive components including polyols, polyamines, and polyisocyanates, The polyisocyanate comprises a polyisocyanate crosslinking agent having more than two functional groups. The crosslinking density derived from polyfunctional components in the reactive component having more than two functional groups is 0.30 mol / kg or more and 0.80 mol / kg or less. The urea group content in the polyurethane urea particles is 0.50 mol / kg or more and 2.00 mol / kg or less. The volume-average particle diameter of the polyurethane urea particles is 1 μm or more and 30 μm or less. A water-based coating agent for synthetic imitation leather.

2. The aqueous coating agent according to claim 1, wherein the polyol comprises at least one polymer polyol selected from the group consisting of polyether polyols and polycarbonate polyols.

3. The aqueous coating agent according to claim 2, wherein the content of the polymer polyol relative to the total mass of the reactive component is 45% by mass or more and 80% by mass or less.

4. The aqueous coating agent according to claim 1, wherein the polyisocyanate comprises at least one aliphatic polyisocyanate selected from the group consisting of chain-type aliphatic polyisocyanates and cyclic aliphatic polyisocyanates.

5. The aqueous coating agent according to claim 1, wherein the 10% compressive strength of the polyurethane urea particles at 25°C is 0.1 MPa or more and 1.4 MPa or less.

Images