Cross-linked polyurethane microparticles, method for producing cross-linked polyurethane microparticles, and paint

Abstract

The present invention provides crosslinked polyurethane microparticles that are less prone to aggregation and have good dispersibility, while also possessing excellent flexibility and maintaining flexibility even under low-temperature conditions, and exhibiting excellent hydrolysis resistance despite being reaction products of raw materials containing polyester polyols. [Solution] The reaction product is obtained by reacting raw materials containing a polyester polyol having constituent units derived from a dicarboxylic acid with 8 or more carbon atoms and constituent units derived from aliphatic diol A, and an isocyanate compound, while the raw materials are dispersed in a liquid medium containing a dispersion stabilizer in the form of fine particles. The aliphatic polyol A is a branched-chain polyol having a branched structure, or a linear polyol having 5 or fewer carbon atoms, and the hydroxyl value of the polyester polyol is 60 to 200 mg KOH / g.

Description

Technical Field

[0001] The present invention relates to crosslinked polyurethane fine particles, a method for producing the crosslinked polyurethane fine particles, and a paint.

Background Art

[0002] Conventionally, vinyl chloride resins, which have good flexibility, flame retardancy, designability, and vacuum formability and a good cost balance, have been widely used as materials for automobile interior materials and the like. However, in recent years, due to demands such as the resolution of the dioxin problem caused by halogen compounds and weight reduction, the frequency of use of thermoplastic polyolefins has been increasing. Thermoplastic polyolefins are resin materials that have various physical properties such as weather resistance and chemical resistance, are flexible without using a plasticizer, and can be made lightweight with low density, and thus are promising as an alternative to vinyl chloride resins. However, molded products such as members made of thermoplastic polyolefins are insufficient in terms of abrasion resistance, flexibility, oil resistance, adhesion, and weather resistance, and it cannot be said that they have a good touch that produces a high-class feeling.

[0003] On the other hand, polyurethane-based resins such as polyurethane resins, polyurea resins, and polyurethane-polyurea resins are resin materials that are excellent in various physical properties such as abrasion resistance, flexibility, and adhesion, and also have suitability for various processing methods. Therefore, polyurethane-based resins are widely used as binders blended in various coating agents, inks, and paints, and as materials for films, sheets, and various molded products.

[0004] For example, three-dimensionally crosslinked polyurethane gel particles have been proposed for use in cosmetics and paints (Patent Documents 1-3). Polyurethane resin beads for paints, obtained by reacting a biomass-derived polyol component with an isocyanate component, have also been proposed (Patent Document 4). Furthermore, a method for producing polyurethane beads for use in paints has been proposed, comprising a step of reacting a polyester polyol, a reaction product of 3-methyl-1,5-pentanediol and adipic acid, with an isocyanate component in water (Patent Document 5). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-189552 [Patent Document 2] Patent No. 5826814 [Patent Document 3] Japanese Patent Publication No. 2010-24319 [Patent Document 4] Japanese Patent Publication No. 2010-18714 [Patent Document 5] Japanese Patent Publication No. 2013-67793 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, conventional resin particles such as polyurethane beads proposed in Patent Documents 1-5, etc., tend to aggregate (adhere) in various liquid media such as organic solvents as flexibility increases, and their dispersibility is not necessarily good. Furthermore, their flexibility and hydrolysis resistance are not necessarily good, and their flexibility is easily impaired under low-temperature conditions, leaving room for improvement.

[0007] This invention has been made in view of the problems of the prior art, and its objective is to provide crosslinked polyurethane fine particles that are less prone to aggregation and have good dispersibility, while also being highly flexible, and that retain their flexibility even under low-temperature conditions, and that have excellent hydrolysis resistance despite being a reaction product of raw materials containing polyester polyol, as well as a method for producing the same.

[0008] Furthermore, an object of the present invention is to provide a coating that has a smooth feel, good grip, excellent flexibility and bendability, and can form a coating film such as a surface treatment film that is less likely to lose flexibility and bendability even under low temperature conditions. [Means for solving the problem]

[0009] In other words, the present invention provides the following crosslinked polyurethane fine particles. [1] A reaction product obtained by reacting a polyester polyol having constituent units derived from a dicarboxylic acid with 8 or more carbon atoms and constituent units derived from aliphatic polyol A, and an isocyanate compound, while the raw materials are dispersed in a liquid medium containing a dispersion stabilizer in the form of fine particles, wherein the aliphatic polyol A is a branched-chain polyol having a branched structure, or a linear polyol having 5 or fewer carbon atoms, and the hydroxyl value of the polyester polyol is 60 to 200 mg KOH / g. [2] The crosslinked polyurethane fine particles according to [1], wherein both the dicarboxylic acid and the aliphatic polyol A are compounds derived from biomass, and the biomass ratio is 50% by mass or more. [3] The crosslinked polyurethane fine particles according to [1] or [2], wherein at least one of the polyester polyol and the isocyanate compound is a trifunctional or more compound. [4] The crosslinked polyurethane fine particles according to [1] or [2], wherein the isocyanate compound is at least one of an aliphatic diisocyanate and a derivative thereof. [5] The crosslinked polyurethane fine particles according to [1] or [2], wherein the isocyanate compound is 1,5-pentamethylene diisocyanate or an isocyanurate of 1,5-pentamethylene diisocyanate. [6] Crosslinked polyurethane fine particles according to any one of [1] to [5], wherein the number of carbon atoms of the dicarboxylic acid is 12 or less. [7] Crosslinked polyurethane fine particles according to any one of [1] to [6], wherein the liquid medium is an organic solvent, and the dispersion stabilizer is a polyurea colloid particle composed of a solvated portion solvated in the organic solvent and a non-solvated portion not solvated in the organic solvent. [8] Crosslinked polyurethane fine particles according to any one of [1] to [6], wherein the liquid medium is an aqueous liquid medium containing water, and the dispersion stabilizer is a surfactant. [9] The crosslinked polyurethane fine particles according to any one of [1] to [8], wherein the raw material further contains aliphatic polyol B, and the amount of aliphatic polyol B in relation to the total of the polyester polyol, the isocyanate compound, and the aliphatic polyol B is 0.1 to 10% by mass.

[10] Crosslinked polyurethane fine particles according to any one of [1] to [9], wherein the volume average particle diameter is 0.1 to 500 μm.

[11] Crosslinked polyurethane fine particles according to any one of [1] to

[10] , wherein the glass transition temperature is -30°C or lower and the 10% compressive strength is 1.0 MPa or lower.

[0010] Furthermore, the present invention provides a method for producing the following crosslinked polyurethane fine particles.

[12] A method for producing crosslinked polyurethane fine particles, comprising the step of reacting a raw material containing a polyester polyol having constituent units derived from a dicarboxylic acid having 8 or more carbon atoms and constituent units derived from aliphatic polyol A and an isocyanate compound while dispersed in fine particles in a liquid medium containing a dispersion stabilizer to form crosslinked polyurethane fine particles as a reaction product, wherein the aliphatic polyol A is a branched-chain polyol having a branched structure or a linear polyol having 5 or fewer carbon atoms, and the hydroxyl value of the polyester polyol is 60 to 200 mg KOH / g.

[0011] Furthermore, the present invention provides the following paints.

[13] A paint containing cross-linked polyurethane fine particles as described in any of [1] to

[11] above.

[14] The paint according to

[13] , further containing a synthetic resin, wherein the amount of crosslinked polyurethane fine particles is 10 to 100 parts by mass per 100 parts by mass of the synthetic resin. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide crosslinked polyurethane fine particles that are less prone to aggregation and have good dispersibility, while also being highly flexible and retaining their flexibility even under low-temperature conditions, and that have excellent hydrolysis resistance despite being reaction products of raw materials containing polyester polyol, as well as a method for producing the same.

[0013] Furthermore, according to the present invention, it is possible to provide a coating that has a smooth feel, good grip, excellent flexibility and bendability, and can form a coating film such as a surface treatment film that is less likely to lose flexibility and bendability even under low temperature conditions. [Modes for carrying out the invention]

[0014] <Cross-linked polyurethane microparticles> Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the crosslinked polyurethane fine particles of the present invention is a reaction product obtained by reacting raw materials containing a polyester polyol and an isocyanate compound in a state of being dispersed in the form of fine particles in a liquid medium containing a dispersion stabilizer. The polyester polyol has a structural unit (i) derived from a dicarboxylic acid having 8 or more carbon atoms and a structural unit (ii) derived from an aliphatic polyol A. The aliphatic polyol A is a branched-chain polyol having a branched structure or a linear polyol having 5 or less carbon atoms, and the hydroxyl value of the polyester polyol is 60 to 200 mgKOH / g. Hereinafter, the details of the crosslinked polyurethane fine particles of the present embodiment will be described.

[0015] (Polyester polyol) The polyester polyol is a resin having a structural unit (i) derived from a dicarboxylic acid having 8 or more carbon atoms and a structural unit (ii) derived from an aliphatic polyol A. It is preferable that the polyester polyol is substantially composed only of the structural unit (i) and the structural unit (ii).

[0016] The dicarboxylic acid has 8 or more carbon atoms. However, if the dicarboxylic acid has too many carbon atoms, its polarity becomes low and it tends to dissolve in the liquid medium. Therefore, the dicarboxylic acid preferably has 12 or less carbon atoms. General polyester polyols are more likely to be hydrolyzed than other polymer polyols such as polyether polyols and polycarbonate polyols. On the other hand, by using a polyester polyol containing a dicarboxylic acid having 8 or more carbon atoms, crosslinked polyurethane fine particles with improved hydrolysis resistance can be obtained. If the number of carbon atoms constituting the dicarboxylic acid molecule is less than 8, the glass transition temperature of the crosslinked polyurethane fine particles may increase, or the flexibility and hydrolysis resistance may decrease.

[0017] Examples of the dicarboxylic acid having 8 or more carbon atoms include suberic acid, sebacic acid, azelaic acid, and dodecanedioic acid. Among them, sebacic acid is preferable.

[0018] Using aliphatic polyol A lowers the glass transition temperature of the crosslinked polyurethane and allows for the production of crosslinked polyurethane fine particles with superior flexibility compared to using polyols other than aliphatic polyol A, such as aromatic polyols. Examples of aliphatic polyol A include branched polyols with branched structures such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol (MPD), and neopentyl glycol, as well as linear polyols with 5 or fewer carbon atoms; low-molar alkylene oxide adducts of these (number-average molecular weight less than 500); and polyhydric alcohols such as glycerin and trimethylolpropane. Among these, 1,3-propanediol is preferred. When linear polyols with 6 or more carbon atoms are used as aliphatic polyol A, the crystallinity of the crosslinked polyurethane increases, reducing the dispersibility of the crosslinked polyurethane fine particles and the flexibility at low temperatures.

[0019] It is preferable that both the dicarboxylic acid and aliphatic polyol A are compounds derived from biomass. By using biomass-derived dicarboxylic acid and aliphatic polyol A, crosslinked polyurethane fine particles with reduced environmental impact can be obtained. Specifically, the biomass ratio of the crosslinked polyurethane fine particles is preferably 50% by mass or more, and more preferably 70% by mass or more.

[0020] The hydroxyl value of the polyester polyol is 60 to 200 mgKOH / g, preferably 70 to 150 mgKOH / g, and more preferably 80 to 140 mgKOH / g, considering the realization of a coating film that can exhibit flexibility at low temperatures. If the hydroxyl value of the polyester polyol is less than 60 mgKOH / g, the flexibility of the crosslinked polyurethane fine particles increases, but the dispersibility decreases. On the other hand, if the hydroxyl value of the polyester polyol is greater than 200 mgKOH / g, the glass transition temperature (Tg) of the crosslinked polyurethane fine particles tends to rise, and the flexibility decreases.

[0021] (Isocyanate compounds) As the isocyanate compound, any of the conventionally known polyisocyanates (diisocyanates) used in the production of polyurethanes can be used. Examples of isocyanate compounds include toluene-2,4-diisocyanate, 4-methoxy-1,3-phenylenediisocyanate, 4-isopropyl-1,3-phenylenediisocyanate, 4-chlor-1,3-phenylenediisocyanate, 4-butoxy-1,3-phenylenediisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis(phenylene isocyanate) (MDI), juliene isocyanate, tolylene isocyanate, xylylene isocyanate (XDI), 1,5-naphthalene isocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, and aromatic diisocyanates such as 4,4'-diisocyanate dibenzyl. Examples include cyanates; aliphatic diisocyanates such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,10-decamethylene diisocyanate; alicyclic diisocyanates such as 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated MDI, and hydrogenated XDI; polyurethane prepolymers obtained by reacting these isocyanate compounds with low molecular weight polyols or polyamines such that the terminals are isocyanate groups; and so on.

[0022] Furthermore, as the isocyanate compound, a polyfunctional isocyanate compound with three or more functions, which is a derivative of the above-mentioned isocyanate compound, can be used. Examples of polyfunctional isocyanate compounds with three or more functions include isocyanurates, biuretes, adducts, and polymers of the above-mentioned isocyanate compounds. In addition, other types of polyisocyanates such as dimers of 2,4-toluylene diisocyanate, triphenylmethane triisocyanate, tris-(p-isocyanatephenyl)thiophosphite, polyfunctional aromatic isocyanates, polyfunctional aromatic aliphatic isocyanates, polyfunctional aliphatic isocyanates, fatty acid-modified polyfunctional aliphatic isocyanates, blocked polyisocyanates, and polyisocyanate prepolymers can also be used.

[0023] The isocyanate compound is preferably at least one of aliphatic diisocyanates and their derivatives. By using aliphatic diisocyanates or their derivatives, yellowing (deterioration of the color of the paint film) can be prevented more effectively than when aromatic diisocyanates are used, for example, when used in paints.

[0024] Furthermore, the isocyanate compound is preferably one of 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, an isocyanurate of 1,5-pentamethylene diisocyanate, or an isocyanurate of 1,6-hexamethylene diisocyanate. Moreover, it is even more preferable if the isocyanate compound is an isocyanurate of 1,5-pentamethylene diisocyanate, because it can further reduce the 10% compressive strength of the crosslinked polyurethane fine particles and facilitate the formation of coating films such as surface treatment films that do not easily lose flexibility and bendability even under low temperature conditions.

[0025] It is preferable that at least one of the polyester polyol and the isocyanate compound is a trifunctional or higher compound. For example, if the isocyanate compound is a bifunctional compound, it is preferable that the polyester polyol is a trifunctional or higher compound. Also, if the polyester polyol is a bifunctional compound, it is preferable that the isocyanate compound is a trifunctional or higher compound. By having at least one of the polyester polyol and the isocyanate compound be a trifunctional or higher compound, three-dimensionally crosslinked polyurethane fine particles can be obtained more easily. Depending on the intended use of the crosslinked polyurethane fine particles, the number of functional groups of the polyester polyol and the isocyanate compound may be selected. Furthermore, the molar ratio of the polyester polyol to the isocyanate compound to be reacted is preferably in the range of NCO group / OH group (molar ratio) = 0.5 to 1.2.

[0026] (Aliphatic polyol B) The raw materials preferably further contain aliphatic polyol B. That is, the crosslinked polyurethane fine particles are preferably reaction products obtained by reacting raw materials containing polyester polyol, isocyanate compound, and aliphatic polyol B under predetermined conditions. For example, if both the polyester polyol and isocyanate compound are bifunctional compounds, aliphatic polyol B can also be a trifunctional or more functional compound.

[0027] As aliphatic polyol B, short-chain polyols conventionally known for their use in the production of polyurethanes can be used. Examples of aliphatic polyol B include those similar to those described above for aliphatic polyol A. Specifically, examples of aliphatic polyol B include aliphatic glycols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; low-molar alkylene oxide adducts of these aliphatic glycols (number-average molecular weight less than 500); polyhydric alcohols such as glycerin and trimethylolpropane; and so on. It is preferable to use a biomass-derived compound as aliphatic polyol B. Aliphatic polyol A and aliphatic polyol B may be the same or different.

[0028] In the raw materials, the amount of aliphatic polyol B in relation to the total of polyester polyol, isocyanate compound, and aliphatic polyol B is preferably 0.1 to 10% by mass, and more preferably 0.1 to 5% by mass. By keeping the amount of aliphatic polyol B within the above range, the glass transition temperature can be lowered.

[0029] (Cross-linked polyurethane microparticles) The crosslinked polyurethane fine particles of this embodiment are reaction products obtained by reacting raw materials containing the aforementioned polyester polyol and isocyanate compound while they are dispersed in a liquid medium containing a dispersion stabilizer. The dispersion stabilizer is a component that functions as a so-called emulsifier to stably disperse the raw materials in a liquid medium in a fine particle form. It should be noted that if the reaction is carried out without dispersing the raw materials in a liquid medium containing a dispersion stabilizer in a fine particle form, for example, in the absence of the dispersion stabilizer, it is substantially impossible to obtain the desired crosslinked polyurethane fine particles. Furthermore, when the raw materials are reacted in the presence of a dispersion stabilizer, it is assumed that the surface of the resulting particles will be coated with the dispersion stabilizer, or that the dispersion stabilizer, which has become even finer, will adhere to the surface of the particles. However, it is difficult or substantially impossible to identify the state of the dispersion stabilizer by analysis or other means.

[0030] The volume-average particle size of the crosslinked polyurethane fine particles is preferably 0.1 to 500 μm, and more preferably 1 to 100 μm. The glass transition temperature of the crosslinked polyurethane fine particles is preferably -30°C or lower, and more preferably -40 to -60°C. Generally, the lower the glass transition temperature, the more flexible the resin fine particles become, but they also tend to aggregate. The crosslinked polyurethane fine particles of this embodiment have a suitable glass transition temperature within the above range, thus achieving a good balance between flexibility and dispersibility.

[0031] Furthermore, the 10% compressive strength of the crosslinked polyurethane fine particles is preferably 1.0 MPa or less, and more preferably 0.05 to 0.2 MPa. Since the preferred 10% compressive strength is within the above range, the crosslinked polyurethane fine particles of this embodiment exhibit excellent flexibility.

[0032] <Method for manufacturing cross-linked polyurethane microparticles> The crosslinked polyurethane fine particles of this embodiment can be manufactured according to the method described below. That is, one embodiment of the method for manufacturing crosslinked polyurethane fine particles of the present invention includes a step (reaction step) in which raw materials containing the aforementioned polyester polyol and isocyanate compound are dispersed in a liquid medium containing a dispersion stabilizer in a fine particle form and reacted to form crosslinked polyurethane fine particles as a reaction product. The details of the method for manufacturing crosslinked polyurethane fine particles of this embodiment will be described below.

[0033] (Reaction process) In the reaction process, raw materials containing polyester polyol and isocyanate compounds are dispersed in a liquid medium containing a dispersion stabilizer in the form of fine particles and then reacted. This allows for the formation of crosslinked polyurethane fine particles, which are the reaction product.

[0034] [Liquid medium] The liquid medium is a medium for reacting raw materials in a dispersed state. Water, water-soluble organic solvents, and water-insoluble organic solvents can be used as the liquid medium.

[0035] [Dispersion stabilizer] Dispersion stabilizers are components that function as emulsifiers to stably disperse raw materials in a liquid medium in the form of fine particles. It is preferable to select and use a dispersion stabilizer appropriately depending on the type of liquid medium. When using an aqueous liquid medium containing water and a water-soluble organic solvent as the liquid medium, more specifically when using water as the liquid medium, it is preferable to use a surfactant as the dispersion stabilizer. As surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can be used. Among these, it is preferable to use a nonionic surfactant. Examples of nonionic surfactants include cellulose derivatives such as hydroxypropyl methylcellulose, as well as alkyl ether type, phenyl ether type, ether ester type, ester type, and amide type nonionic surfactants.

[0036] Furthermore, when using an organic solvent as a liquid medium, or more specifically when using a non-water-soluble organic solvent as a liquid medium, it is preferable to use polyurea colloid particles composed of a solvated portion solvated in the organic solvent and a non-solvated portion not solvated in the organic solvent as a dispersion stabilizer.

[0037] Furthermore, reacting a raw material dispersed in particulate form in an organic solvent containing polyurea colloid particles as a dispersion stabilizer is preferable because it yields crosslinked polyurethane fine particles with improved hydrolysis resistance compared to reacting a raw material dispersed in particulate form in water containing a surfactant as a dispersion stabilizer.

[0038] It is preferable to use an organic solvent that does not contain active hydrogen groups. Examples of such organic solvents include hydrocarbon solvents such as pentane, hexane, heptane, octane, decane, petroleum ether, petroleum benzine, ligroin, petroleum spirits, cyclohexane, methylcyclohexane, toluene, xylene, ethylcyclohexane, and dimethylcyclohexane, as well as dimethylpolysiloxane. In particular, from the viewpoint of simplifying the process of separating the generated crosslinked polyurethane fine particles, it is preferable to use an organic solvent with a boiling point of 150°C or lower.

[0039] The particle size of the non-solvated portion constituting the polyurea colloid particles is preferably 0.01 to 1.0 μm. Polyurea colloid particles can be formed by reacting an oil-modified polyol, a polyisocyanate (or a terminal NCO prepolymer made from these compounds) and a polyamine in an organic solvent.

[0040] As the reaction progresses, insoluble urea domains are formed in the organic solvent through hydrogen bonding between urea bonds. Simultaneously, the molecular chains of the lipid-modified polyol are solvated in the organic solvent, and it is thought that stable polyurea colloid particles, whose size is prevented by aggregation of the insoluble urea domains, are formed.

[0041] A prepolymer having an NCO group is synthesized by reacting an oil-modified polyol with a polyisocyanate in an organic solvent or without a solvent. Then, an organic solvent is added to dilute the mixture and a solution with a concentration of 5-70% by mass is prepared. Subsequently, while stirring the prepared solution, a solution of polyamine with a concentration of 1-20% by mass is gradually added to carry out a polyurea formation reaction, thereby obtaining a polyurea colloid solution containing polyurea colloid particles.

[0042] The number-average molecular weight of the oil-modified polyol is preferably 700 to 3,000. Examples of oil-modified polyols include those obtained by methods such as alcoholicylation of various oils and fats using lower alcohols or glycols, partial saponification of oils and fats, and esterification of hydroxyl-containing fatty acids with glycols. Examples of hydroxyl-containing fatty acids include ricinoleic acid, 12-hydroxystearic acid, castor oil fatty acid, and hydrogenated castor oil fatty acid.

[0043] The reaction between the oil-modified polyol and the polyisocyanate is preferably carried out under conditions where 1 < (NCO group / OH group) ≤ 2 (molar ratio) to control the molecular weight of the solvated prepolymer. The number-average molecular weight of the resulting prepolymer is preferably 500 to 15,000. Examples of polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate, water-added TDI, water-added MDI, isophorone diisocyanate, and hydrogenated XDI, as well as alicyclic diisocyanates.

[0044] Examples of polyamines include short-chain diamines, aliphatic polyamines, alicyclic polyamines, aromatic polyamines, and hydrazines. Examples of short-chain diamines and aliphatic polyamines include methylenediamine, ethylenediamine, diaminopropane, diaminobutane, trimethylenediamine, trimethylhexamethylenediamine, hexamethylenediamine, octamethylenediamine, polyoxypropylenediamine, and polyoxypropylenetriamine. Examples of alicyclic polyamines include cyclopentanediamine, cyclohexyldiamine, 4,4-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, bis-aminopropylpiperazine, thiourea, methyliminobispropylamine, norbornanediamine, and isophoronediamine. Examples of aromatic polyamines include phenylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(phenylamine), 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl sulfone. Examples of hydrazines include hydrazine, carbohydrazide, adipic acid dihydrazide, sebacate acid dihydrazide, and phthalate dihydrazide.

[0045] Polyurea colloid particles function as either a water-on-water (W / O) or water-on-water (O / O) emulsifier. By adjusting the amount of polyurea colloid particles added to the polyisocyanate and polyester polyol, the particle size of the resulting cross-linked polyurethane microparticles can be controlled. For example, the more polyurea colloid particles added, the smaller the particle size of the resulting cross-linked polyurethane microparticles. Conversely, the less polyurea colloid particles added, the larger the particle size of the resulting cross-linked polyurethane microparticles.

[0046] (Other processes) Through the above reaction process, cross-linked polyurethane fine particles are formed, and a dispersion containing these fine particles can be obtained. By separating and removing the liquid medium from the dispersion under atmospheric pressure or under reduced pressure, the desired cross-linked polyurethane fine particles can be obtained. Examples of equipment for separating and removing the liquid medium from the dispersion include spray dryers, vacuum dryers with filtration devices, vacuum dryers with stirring devices, and shelf dryers. The drying temperature should be set appropriately considering the vapor pressure of the liquid medium, the softening temperature of the cross-linked polyurethane fine particles, and the particle size of the cross-linked polyurethane fine particles. Specifically, drying can be performed under reduced pressure at 40 to 130°C.

[0047] <Paint> A paint can be obtained by using the cross-linked polyurethane fine particles described above. That is, one embodiment of the paint of the present invention contains the cross-linked polyurethane fine particles described above. In addition to the cross-linked polyurethane fine particles, the paint of this embodiment can be obtained by dispersing or dissolving a synthetic resin and various additives used as needed in a liquid medium such as water. The content of the synthetic resin in the paint is preferably 10 to 80% by mass, and more preferably 20 to 70% by mass, based on the solid content in the paint. The content of the cross-linked polyurethane fine particles in the paint is preferably 10 to 100 parts by mass, and more preferably 10 to 50 parts by mass, per 100 parts by mass of synthetic resin. The solid content in the paint is usually about 1 to 95% by mass.

[0048] Examples of synthetic resins include polyurethane resins, acrylic resins, silicone resins, and amide resins. Examples of additives include antioxidants such as hindered phenols, phosphites, and thioethers; light stabilizers such as hindered amines; ultraviolet absorbers such as benzophenones and benzotriazoles; gas discoloration stabilizers such as hydrazines; and metal deactivators.

[0049] Furthermore, in addition to design-enhancing agents such as organic and inorganic microparticles, antifungal agents and flame retardants can be used as appropriate. Examples of organic and inorganic microparticles include silica, silicone resin microparticles, fluororesin microparticles, acrylic resin microparticles, urethane resin microparticles, silicone-modified urethane resin microparticles, polyethylene microparticles, and reactive siloxanes.

[0050] Because the coating of this embodiment contains the aforementioned cross-linked polyurethane fine particles, it has a smooth feel, good grip, excellent flexibility and bendability, and can form coating films such as surface treatment films that are less likely to lose flexibility and bendability even under low temperature conditions. For this reason, the cross-linked polyurethane fine particles of this embodiment and the coating containing them are useful as materials for forming automotive interior materials such as instrument panels, surface materials for furniture, and surface materials for miscellaneous goods that come into close contact with the skin, such as headphones. [Examples]

[0051] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0052] <Preparation of polyurea colloid solution> (Preparation Example 1) 100 parts of a bifunctional oil-modified polyol (trade name "URIC Y-202", manufactured by Ito Oil Co., Ltd., hydroxyl value: 119.5 mg KOH / g) and 100 parts of n-octane were placed in a reaction vessel, and the oil-modified polyol was dissolved. The temperature was controlled to 50°C while stirring, and 47.3 parts of isophorone diisocyanate (NCO / OH (molar ratio) = 2) were gradually added over 1 hour. After reacting at 50°C for 3 hours, the temperature was raised to 80°C and the reaction was continued for another 3 hours. n-octane was added to a concentration of 50% to obtain a solution (PP-1) containing a prepolymer with an NCO group content of 3.0%. The molecular weight of the prepolymer was 1,383. 40 parts of the obtained PP-1 and 60 parts of n-octane were placed in a reaction vessel. The temperature was controlled to 70°C while stirring, and 24.3 parts of an n-octane solution of isophoronediamine (isophoronediamine concentration: 10%) were gradually added over 5 hours to allow the reaction to proceed. This yielded a polyurea colloid solution (C-1) (solid content: 18.0%) with a concentration of (polyamine (urea bond) / prepolymer chain) × 100 = 12.15%. The resulting polyurea colloid solution (C-1) was a stable, milky blue solution.

[0053] <Preparation of polyester polyol> Polyester polyols A to J, as shown in Table 1, were prepared. The meanings of the abbreviations in Table 1 are explained below. • 1,3-PD; 1,3-propanediol MPD: 3-methyl-1,5-pentanediol TMP: Trimethylolpropane · 1,6-HD: 1,6-hexanediol

[0054] TIFF2026047222000001.tif89170

[0055] <Preparation of isocyanate compounds> The following isocyanate compounds A to D were prepared. Note that isocyanate compound C is derived from petroleum resources, while isocyanate compounds A, B, and D are derived from biomass. • Isocyanate compound A: A modified form of a trifunctional isocyanate compound represented by the following formula (B), trade name "Stavio D-376N", manufactured by Mitsui Chemicals, Inc., isocyanurate of pentamethylene diisocyanate, NCO% = 23.6% • Isocyanate compound B: A trifunctional isocyanate compound represented by the following formula (B), trade name "Stavio D-370N", manufactured by Mitsui Chemicals, Inc., isocyanurate derivative of pentamethylene diisocyanate, NCO% = 25.0 • Isocyanate compound C: A trifunctional isocyanate compound represented by the following formula (A), trade name "Duranate TPA-100", manufactured by Asahi Kasei Corporation, isocyanurate derivative of hexamethylene diisocyanate, NCO% = 23.1 • Isocyanate compound D: Pentamethylene diisocyanate, trade name "Stavio PDI", manufactured by Mitsui Chemicals, NCO%=54.5

[0056] TIFF2026047222000002.tif47170

[0057] <Manufacturing of cross-linked polyurethane microparticles> (Example 1) Twenty parts of polyester polyol A were heated to 60°C and dissolved. Then, 0.2 parts of biomass-derived 1,3-propanediol and 7.8 parts of isocyanate compound A were added and mixed to obtain a mixture. In addition, five parts of the polyurea colloid solution (C-1) obtained in Preparation Example 1 and 25 parts of n-octane were placed in a stainless steel container and mixed. The above mixture was gradually added to the container and reacted by processing with a homogenizer for 15 minutes. This formed cross-linked polyurethane fine particles, and an emulsion containing the cross-linked polyurethane fine particles was obtained. The obtained emulsion was stable without separation, and the average dispersed particle size of the dispersed phase was 5 μm.

[0058] (Examples 2-7, Comparative Examples 1-6) Except for using the types and amounts of polyester polyols, etc., shown in the upper section of Tables 2-1 and 2-2, cross-linked polyurethane fine particles were formed in the same manner as in Example 1 described above, and an emulsion containing the cross-linked polyurethane fine particles was obtained. All emulsions were stable without separation, and the average dispersed particle size of the dispersed phase was 5 μm.

[0059] (Example 8) Twenty parts of polyester polyol A were heated to 60°C and dissolved. Then, 0.5 parts of biomass-derived 1,3-propanediol and 7.3 parts of isocyanate compound A were added and mixed to obtain a mixture. In addition, five parts of hydroxypropyl methylcellulose (trade name "Metrol 90SH-100", manufactured by Shin-Etsu Chemical Co., Ltd.) and water were mixed in a stainless steel container. The above mixture was gradually added to the container and reacted using a homogenizer for 15 minutes. This formed cross-linked polyurethane microparticles, and an emulsion containing the cross-linked polyurethane microparticles was obtained. The obtained emulsion was stable without separation, and the average dispersed particle size of the dispersed phase was 5 μm.

[0060] <Rating> (dispersibility) A first dispersion was prepared by mixing cross-linked polyurethane microparticles with hexane and manually stirring. A second dispersion was prepared by mixing cross-linked polyurethane microparticles with hexane and then using an ultrasonic disperser to break up aggregates with 30W ultrasound for 3 minutes. The volume-average particle size (MV1) of the cross-linked polyurethane microparticles in the first dispersion and the volume-average particle size (MV2) of the cross-linked polyurethane microparticles in the second dispersion were measured using a particle size distribution analyzer (product name "MT3300II," manufactured by Microtrac-Bell). The "MV1 / MV2" value was calculated, and the dispersibility of the cross-linked polyurethane microparticles was evaluated according to the evaluation criteria shown below. A larger "MV1 / MV2" value indicates a greater tendency to aggregate (larger apparent diameter of the microparticles). The results are shown in the lower section of Tables 2-1 and 2-2. ○: The value of "MV1 / MV2" was less than 1.2. △: The value of "MV1 / MV2" was between 1.2 and 2.0. ×: The value of "MV1 / MV2" was greater than 2.0.

[0061] (Biomass ratio) Using an accelerator mass spectrometer, carbon-12 in cross-linked polyurethane nanoparticles ( 12 C) and carbon-14 ( 14 The abundance ratio of C) was measured. 12 C and 14 The biomass ratio (%) of cross-linked polyurethane fine particles was calculated from the proportion of carbon (C). The results are shown in the lower section of Tables 2-1 and 2-2.

[0062] (Glass transition temperature) The glass transition temperature Tg (°C) of the crosslinked polyurethane fine particles was measured using a differential scanning calorimeter (product name "DSC-60A", manufactured by Shimadzu Corporation). The results are shown in the lower section of Tables 2-1 and 2-2. Crosslinked polyurethane fine particles were obtained in the same manner as in Example 1 described above, except that the amount of aliphatic polyol B (1,3-propanediol) in the total of polyester polyol, isocyanate compound, and aliphatic polyol B was set to 15%. The glass transition temperature Tg (°C) of the obtained crosslinked polyurethane fine particles was -20°C.

[0063] (10% compressive strength) The 10% compressive strength (MPa) of cross-linked polyurethane microparticles was measured using a microcompression tester (product name "MCT-511," manufactured by Shimadzu Corporation). The 10% compressive strength is the force (MPa) required to crush the cross-linked polyurethane microparticles by 10%, and a smaller value indicates softer material. The results are shown in the lower section of Tables 2-1 and 2-2.

[0064] (Hydrolysis resistance) Cross-linked polyurethane microparticles were placed in a constant temperature and humidity chamber set to 70°C and 95% humidity and left for 8 weeks. After observation, the hydrolysis resistance of the cross-linked polyurethane microparticles was evaluated according to the evaluation criteria shown below. The results are shown in the lower section of Tables 2-1 and 2-2. ○: Remained in its initial state (particulate state). △: It had aggregated and become a solid. ×: It had liquefied.

[0065] TIFF2026047222000003.tif105170

[0066] TIFF2026047222000004.tif114170

[0067] <Preparation of paint> (Examples 8-14, Comparative Examples 7-12) The cross-linked polyurethane fine particles obtained in Examples 1-7 and Comparative Examples 1-6, polyurethane aqueous dispersion (product name "Rezamin D-6065NP", manufactured by Dainichi Seika Kogyo Co., Ltd., solid content 30%), additive (product name "Rezamin D-340 Leveling Agent", manufactured by Dainichi Seika Kogyo Co., Ltd., solid content 100%), and water were blended in the proportions (unit: parts) shown in Table 3 to prepare a paint with a solid content of 30%.

[0068] <Rating> (Coating film low temperature flexibility) A coating prepared using a bar coater was applied to a PVC sheet. Using a drying oven, the sheet was dried at 120°C for 1 minute to obtain a test sheet with a coating film thickness of 10 μm. From the obtained test sheet, a test piece measuring 50 mm in width and 150 mm in length (evaluation range 100 mm) was cut out. Using a dematcher tester (model "NO.119-L DEMATTYIA FLEXIMG TESTER", manufactured by Yasuda Seiki Seisakusho Co., Ltd.), a bending test was performed on the test piece under the conditions of temperature: -10°C and bending range: 72~108%, and the low-temperature flexibility of the coating film was evaluated according to the evaluation criteria shown below. The results are shown in Table 3. ○: It did not break even after being bent 30,000 times. △: It did not break even after being bent 10,000 times. ×: Broke after 10,000 flexes.

[0069] TIFF2026047222000005.tif126170 [Industrial applicability]

[0070] The crosslinked polyurethane fine particles of the present invention are useful as materials for automotive interior materials such as instrument panels, surface materials for furniture, and surface materials for accessories that come into close contact with the skin, such as headphones.

Claims

1. The reaction product is obtained by reacting raw materials containing a polyester polyol having structural units derived from a dicarboxylic acid with 8 or more carbon atoms and structural units derived from aliphatic polyol A, and an isocyanate compound, while these materials are dispersed in fine particles in a liquid medium containing a dispersion stabilizer. The aliphatic polyol A is a branched-chain polyol having a branched structure, or a linear polyol having 5 or fewer carbon atoms. Crosslinked polyurethane fine particles having a hydroxyl value of 60 to 200 mg KOH / g of the aforementioned polyester polyol.

2. The dicarboxylic acid and the aliphatic polyol A are both compounds derived from biomass. The crosslinked polyurethane fine particles according to claim 1, wherein the biomass ratio is 50% by mass or more.

3. The crosslinked polyurethane fine particles according to claim 1, wherein at least one of the polyester polyol and the isocyanate compound is a trifunctional or more compound.

4. The crosslinked polyurethane fine particles according to claim 1, wherein the isocyanate compound is at least one of an aliphatic diisocyanate and a derivative thereof.

5. The crosslinked polyurethane fine particles according to claim 1, wherein the isocyanate compound is 1,5-pentamethylene diisocyanate or an isocyanurate of 1,5-pentamethylene diisocyanate.

6. The crosslinked polyurethane fine particles according to claim 1, wherein the number of carbon atoms in the dicarboxylic acid is 12 or less.

7. The aforementioned liquid medium is an organic solvent. The crosslinked polyurethane fine particles according to claim 1, wherein the dispersion stabilizer is a polyurea colloid particle composed of a solvated portion solvated in the organic solvent and a non-solvated portion not solvated in the organic solvent.

8. The aforementioned liquid medium is an aqueous liquid medium containing water. The crosslinked polyurethane fine particles according to claim 1, wherein the dispersion stabilizer is a surfactant.

9. The aforementioned raw materials further contain aliphatic polyol B, The crosslinked polyurethane fine particles according to claim 1, wherein the amount of aliphatic polyol B in relation to the total of the polyester polyol, the isocyanate compound, and the aliphatic polyol B is 0.1 to 10% by mass.

10. The crosslinked polyurethane fine particles according to claim 1, wherein the volume-average particle diameter is 0.1 to 500 μm.

11. The glass transition temperature is below -30°C. The crosslinked polyurethane fine particles according to claim 1, wherein the 10% compressive strength is 1.0 MPa or less.

12. The process involves reacting a polyester polyol having structural units derived from a dicarboxylic acid with eight or more carbon atoms and structural units derived from aliphatic polyol A, and an isocyanate compound, in a liquid medium containing a dispersion stabilizer, while dispersed in fine particles, to form crosslinked polyurethane fine particles as a reaction product. The aliphatic polyol A is a branched-chain polyol having a branched structure, or a linear polyol having 5 or fewer carbon atoms. A method for producing crosslinked polyurethane fine particles having a hydroxyl value of 60 to 200 mg KOH / g of the polyester polyol.

13. A paint containing crosslinked polyurethane fine particles as described in any one of claims 1 to 11.

14. It further contains synthetic resin, The paint according to claim 13, wherein the amount of crosslinked polyurethane fine particles is 10 to 100 parts by mass per 100 parts by mass of the synthetic resin.

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