阅读说明：本技术 聚酰胺微粒的制造方法及聚酰胺微粒 (Method for producing polyamide microparticles and polyamide microparticles ) 是由 浅野到 于 2018-05-07 设计创作，主要内容包括：一种聚酰胺微粒的制造方法,通过使聚酰胺的单体(A)在聚合物(B)的存在下,并且在要得到的聚酰胺的结晶化温度以上的温度下进行聚合来制造聚酰胺微粒,在聚合开始时使聚酰胺的单体(A)和聚合物(B)均匀地溶解,并在聚合后析出聚酰胺微粒。一种聚酰胺微粒,其数均粒径为0.1～100μm,正球度为90以上,粒径分布指数为3.0以下,亚麻籽油吸油量为100mL/100g以下,结晶化温度为150℃以上。特别是可以使结晶化温度高的聚酰胺作为表面平滑且粒度分布窄,正球度高的微粒而提供。(A process for producing polyamide fine particles, which comprises polymerizing a monomer (A) of a polyamide in the presence of a polymer (B) at a temperature not lower than the crystallization temperature of the polyamide to be obtained to produce polyamide fine particles, wherein the monomer (A) and the polymer (B) of the polyamide are uniformly dissolved at the start of the polymerization, and the polyamide fine particles are precipitated after the polymerization. Polyamide microparticles having a number average particle diameter of 0.1 to 100 μm, a positive sphericity of 90 or more, a particle size distribution index of 3.0 or less, an oil absorption of linseed oil of 100mL/100g or less, and a crystallization temperature of 150 ℃ or more. In particular, polyamide having a high crystallization temperature can be provided as fine particles having a smooth surface, a narrow particle size distribution, and a high sphericity.)

1. A process for producing polyamide microparticles, which comprises polymerizing a monomer (A) of a polyamide in the presence of a polymer (B) at a temperature not lower than the crystallization temperature of the polyamide to be obtained, wherein the monomer (A) and the polymer (B) of the polyamide are uniformly dissolved at the start of the polymerization, and the polyamide microparticles are precipitated after the polymerization.

2. The method for producing polyamide microparticles according to claim 1, wherein the polyamide microparticles are further produced in the presence of a solvent (C) for the monomer (A) and the polymer (B).

3. The process for producing polyamide microparticles according to claim 1 or 2, wherein the square of the difference in solubility parameter between the monomer (A) and the polymer (B) is in the range of 0.1 to 25, and the square of the difference in solubility parameter between the polyamide and the polymer (B) is in the range of 0.1 to 16.

4. The process for producing polyamide microparticles according to claim 2 or 3, wherein the solvent (C) is water.

5. The method for producing polyamide microparticles according to any one of claims 1 to 4, wherein polymer (B) has no polar group or has any one selected from a hydroxyl group and a mercapto group.

6. The method for producing polyamide microparticles according to any one of claims 1 to 5 wherein the polymer (B) is polyethylene glycol, polypropylene glycol, poly-1, 4-butanediol, a polyethylene glycol-polypropylene glycol copolymer, or an alkyl ether thereof.

7. The process for producing polyamide microparticles according to any one of claims 1 to 6, wherein the weight average molecular weight of polymer (B) is 500 to 500000.

8. Polyamide microparticles having a number average particle diameter of 0.1 to 100 μm, a positive sphericity of 90 or more, a particle size distribution index of 3.0 or less, an oil absorption of linseed oil of 100mL/100g or less, and a crystallization temperature of 150 ℃ or more.

9. The polyamide microparticles according to claim 8, wherein the polyamide constituting the polyamide microparticles is selected from any one of polyamide 6, polyamide 66, and a copolymer thereof.

10. The polyamide microparticles according to claim 8 or 9, wherein a weight average molecular weight of polyamide constituting the polyamide microparticles is 8000 or more.

Technical Field

The present invention relates to a method for producing polyamide fine particles by a simple method, and polyamide fine particles comprising polyamide having a high crystallization temperature, a smooth surface, a narrow particle size distribution, and a high positive sphericity.

Background

Polyamide fine particles are used in various applications such as powder coating materials because of their characteristics of high toughness, flexibility, and high heat resistance. Among them, polyamide 12 fine particles having a spherical shape and a solid and smooth surface, which are made of polyamide 12 as a material and have no pores inside, can provide a good skin feel derived from a smooth surface shape in addition to the flexibility of the resin itself, and are used for high-quality cosmetics and coating materials.

On the other hand, in the case of polyamide resins having a further high crystallization temperature, such as polyamide 6 and polyamide 66, since they have higher versatility and melting point than polyamide 12, they are likely to be widely used for applications having higher heat resistance, and they can be produced into particles having irregular and porous shapes and particles having a wide particle size distribution.

Disclosure of Invention

Problems to be solved by the invention

However, the techniques of patent documents 1 and 2 produce porous fine particles because the solubility in a solvent is reduced and the polyamide precipitates.

The techniques of patent documents 3 and 4 produce particles from unmixed raw materials, and therefore can produce only fine particles having a wide particle size distribution.

In the techniques using anionic polymerization of patent documents 5 and 6, since an initiating agent is an inflammable and flammable medium or solvent, polymerization at a high temperature is difficult, and solubility is reduced to precipitate polyamide in the solvent, thereby producing fine particles of an indefinite shape. Further, a complicated process is required in which a large amount of an organic solvent is required to remove various media, solvents, and polymers.

In the present invention, a method for producing polyamide fine particles by a simple method, and further a polyamide fine particle comprising a polyamide having a high crystallization temperature, having a smooth surface, a narrow particle size distribution, and a high sphericity are provided.

Means for solving the problems

In order to solve the above problems, the method for producing polyamide microparticles of the present invention has the following configuration.

That is to say that the first and second electrodes,

a process for producing polyamide microparticles by polymerizing a monomer (A) of a polyamide in the presence of a polymer (B) at a temperature not lower than the crystallization temperature of the polyamide to be obtained, wherein the monomer (A) and the polymer (B) of the polyamide are uniformly dissolved at the start of the polymerization, and the polyamide microparticles are precipitated after the polymerization.

The polyamide microparticles of the present invention have the following structure. That is to say that the first and second electrodes,

polyamide microparticles having a number average particle diameter of 0.1 to 100 μm, a positive sphericity of 90 or more, a particle size distribution index of 3.0 or less, an oil absorption of linseed oil of 100mL/100g or less, and a crystallization temperature of 150 ℃ or more.

In the method for producing polyamide microparticles of the present invention, it is preferable to further produce polyamide microparticles in the presence of a solvent (C) for the monomer (a) and the polymer (B).

In the method for producing polyamide microparticles of the present invention, the square of the difference in solubility parameter between the monomer (a) and the polymer (B) is preferably in the range of 0.1 to 25, and the square of the difference in solubility parameter between the polyamide and the polymer (B) is preferably in the range of 0.1 to 16.

In the method for producing polyamide microparticles of the present invention, the solvent (C) is preferably water.

In the method for producing polyamide microparticles of the present invention, it is preferable that the polymer (B) has no polar group or that the polymer (B) has any one selected from a hydroxyl group and a mercapto group.

In the method for producing polyamide microparticles of the present invention, the polymer (B) is preferably polyethylene glycol, polypropylene glycol, poly-1, 4-butanediol, a polyethylene glycol-polypropylene glycol copolymer, or an alkyl ether thereof.

In the method for producing polyamide microparticles of the present invention, the polymer (B) preferably has a molecular weight of 500 to 500,000.

The polyamide fine particles of the present invention preferably have polyamide constituting the polyamide fine particles selected from any one of polyamide 6, polyamide 66 and a copolymer thereof.

The polyamide fine particles of the present invention preferably have a weight average molecular weight of the polyamide constituting the polyamide fine particles of 8,000 or more.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the production method of the present invention, a polyamide having a high crystallization temperature can be produced into fine particles having a spherical shape and a smooth surface by a safe and simple method. The polyamide fine particles have both high heat resistance and chemical resistance inherent in polyamide having a high crystallization temperature, and a narrow particle size distribution, a positive spherical surface and a smooth surface, and therefore have sliding properties, and can be suitably used for paints, adhesives, inks, toner light diffusers, spacers for liquid crystals, matting agents, additives for polymer alloys, carriers for various catalysts, chromatography carriers, automobile parts, aircraft parts, electronic parts, additives for cosmetics, and medical carriers. In particular, the heat resistance derived from a high crystallization temperature, the spherical shape, the smooth surface morphology and the uniform particle size can be applied to a highly functional coating material or the like under severe conditions which have not been used conventionally. Further, in cosmetic applications, the polyamide has an increased amide group concentration, so that the polyamide has an increased moisture retention property, and can have both a smooth and homogeneous texture and a moist texture due to a spherical shape and a uniform particle diameter.

Drawings

Fig. 1 is a scanning electron micrograph of polyamide fine particles obtained in example 1.

Fig. 2 is a scanning electron micrograph of the polyamide fine particles obtained in example 2.

Fig. 3 is a scanning electron micrograph of polyamide fine particles obtained in example 8.

Fig. 4 is a scanning electron micrograph of polyamide fine particles obtained in example 10.

Fig. 5 is a scanning electron micrograph of the polyamide fine particles obtained in comparative example 3.

Detailed Description

The present invention will be described in detail below.

The present invention is a method for producing polyamide microparticles by polymerizing a monomer (a) of a polyamide in the presence of a polymer (B) at a temperature higher than the crystallization temperature of the polyamide obtained by polymerizing the monomer (a), characterized in that the monomer (a) and the polymer (B) of the polyamide are uniformly dissolved at the start of polymerization, and polyamide microparticles are precipitated after polymerization, whereby polyamide microparticles having a high crystallization temperature and a higher melting point, which have been difficult in the conventional methods, are also obtained which are spherical, smooth in surface, fine, and have a narrow particle size distribution.

Whether or not the monomer (A) of the polyamide was uniformly dissolved in the polymer (B) at the start of polymerization was confirmed by visual observation that the reaction vessel was a transparent solution. When the polymer (B) is in the form of a suspension or a phase separated into 2 phases at the start of polymerization, the monomer (A) which is a polyamide is not compatible with the polymer (B), and it is necessary to form aggregates, strongly stir the polymer, or the like. In this case, the monomer (a) and the polymer (B) of the polyamide may be homogenized by using the solvent (C) and then the polymerization may be started. Whether or not the polyamide fine particles were precipitated after the polymerization was confirmed by visual observation that the reaction vessel was in a suspension state. When the solution is a homogeneous solution at the end of polymerization, the polyamide and the polymer (B) are uniformly compatible with each other and become aggregates or porous particles by cooling or the like.

The polyamide constituting the polyamide fine particles of the present invention is a polymer having a structure containing an amide group, and is produced by a polycondensation reaction of an amino acid as the monomer (a) of the polyamide, an anionic ring-opening polymerization using a lactam and an initiator, a cationic ring-opening polymerization, a ring-opening polymerization after hydrolysis using water or the like, a polycondensation reaction of a dicarboxylic acid and a diamine or a salt thereof, or the like. In the case of lactams, uniform solution of the initiator with the monomer (a) and the polymer (B) cannot be formed, and since the initiator is pyrophoric, polymerization at a temperature equal to or higher than the crystallization temperature of polyamide from which polyamide fine particles having a regular spherical and smooth surface are easily obtained is difficult, and therefore, cationic polymerization and ring-opening polymerization using water or the like are preferable, and in polymerization at a temperature equal to or higher than the crystallization temperature of the obtained polyamide, ring-opening polymerization using water or the like is most preferable from the viewpoint of suppressing coloring, crosslinked product, and gel product of the polyamide caused by the initiator.

Specific examples of the monomer (A) of the polyamide which is a raw material of the polyamide fine particles in the production method of the present invention include monomers obtained from amino acids such as aminocaproic acid, aminoundecanoic acid, aminododecanoic acid and p-methylbenzoic acid, lactams such as epsilon-caprolactam and laurolactam, dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 1, 4-cyclohexanedicarboxylic acid and 1, 3-cyclohexanedicarboxylic acid, and dicarboxylic acids such as ethylenediamine, 1, 3-propylenediamine, 1, 4-butylenediamine, 1, 5-pentylenediamine, 1, 6-hexylenediamine, 1, 7-heptylenediamine, 1, 8-octylenediamine, 1, 9-nonylenediamine, decylenediamine, undecylenediamine, dodecylenediamine, And a mixture of diamines selected from the group consisting of 1, 4-cyclohexanediamine, 1, 3-cyclohexanediamine, 4 ' -diaminodicyclohexylmethane, and 3,3 ' -dimethyl-4, 4 ' -diaminodicyclohexylmethane, and salts thereof. These monomers (a) may be used in an amount of 2 or more, and may contain other copolymerizable components, as long as the scope of the present invention is not impaired. From the viewpoint of improving the solubility of the monomer (A) and the polymer (B), and narrowing the particle size distribution of the polyamide fine particles to be obtained, aminocaproic acid, epsilon-caprolactam, 1, 6-hexamethylenediamine and adipic acid are preferable, aminocaproic acid, epsilon-caprolactam are more preferable, and epsilon-caprolactam is most preferable.

Specific examples of the polyamide produced by polymerizing the monomer (A) include polycaprolactam (polyamide 6), polyhexamethyleneadipamide (polyamide 66), polytetramethyleneadipamide (polyamide 46), polytetramethyleneadipamide (polyamide 410), polypentylglycol adipamide (polyamide 56), polypentylglycol sebacamide (polyamide 510), polyhexamethylenesebacamide (polyamide 610), polyhexamethylenedodecanoamide (polyamide 612), polysebadimide (polyamide 106), polysebadimide (polyamide 126), polysebadimide (polyamide 1010), polyundecanolactam (polyamide 11), polydodecanolactam (polyamide 12), polyhexamethylene terephthalamide (polyamide 6T), polysebadimide (polyamide 10T), polycaprolactam/polyhexamethylene adipamide copolymer (polyamide 6/66), and the like. They may contain other copolymerizable components as long as the scope of the present invention is not impaired. In the production method of the present invention, the crystallization temperature is preferably 150 ℃ or higher, and more preferably any one selected from the group consisting of polyamide 6, polyamide 66 and copolymers thereof, from the viewpoint that the particle size of the obtained polyamide fine particles is fine and the particle size distribution is narrow, and further the heat resistance of the polyamide constituting the obtained polyamide fine particles is high.

The weight average molecular weight of the polyamide constituting the polyamide fine particles is preferably 8,000 to 3,000,000. From the viewpoint of inducing phase separation from the polymer (B), the weight average molecular weight is more preferably 10,000 or more, still more preferably 15,000 or more, and most preferably 20,000 or more. In the present invention, the viscosity during polymerization depends on the polymer (B), and therefore an increase in viscosity due to an increase in the molecular weight of the polyamide is suppressed. Therefore, there is an advantage that the polymerization time of the polyamide is prolonged and the molecular weight can be made extremely high. However, if the polymerization time is too long, a side reaction product of the polyamide such as a crosslinked product, deterioration of the polymer (B), and the like occur, and therefore the weight average molecular weight of the polyamide is more preferably 2,000,000 or less, and still more preferably 1,000,000 or less.

The weight average molecular weight of the polyamide constituting the polyamide fine particles is a weight average molecular weight in terms of polymethyl methacrylate, which is a value measured by gel permeation chromatography using hexafluoroisopropanol as a solvent.

The polymer (B) in the present invention means a polymer which is dissolved in the polyamide monomer (A) at the start of polymerization but is incompatible with the polyamide after polymerization. The dissolution is judged by whether or not the polymer (B) and the monomer (a) are uniformly dissolved under the conditions of temperature and pressure at which the polymerization starts. The incompatibility of the polymer (B) with the polyamide is judged by whether it is a suspension or separates into 2 phases under the conditions of temperature and pressure after polymerization. The judgment of whether the solution was a homogeneous solution, suspension, or 2-phase separation was carried out by visually checking the reaction vessel.

Further described in detail, it is preferable that the polymer (B) is non-reactive with the polyamide monomer from the viewpoint of precipitating the polyamide fine particles from a uniform solution. Specifically, the polymer (B) preferably does not have a polar group that reacts with a carboxyl group or an amino group that forms an amide group of the polyamide, or the polymer (B) preferably has a polar group that has low reactivity with a carboxyl group or an amino group. Examples of the polar group that reacts with a carboxyl group and an amino group include an amino group, a carboxyl group, an epoxy group, and an isocyanate group. The polar group having low reactivity with a carboxyl group or an amino group includes a hydroxyl group, a mercapto group, and the like, and from the viewpoint of suppressing the crosslinking reaction, the polar group in the polymer (B) is preferably 4 or less, more preferably 3 or less, and most preferably 2 or less.

Further, from the viewpoint of making the produced polyamide fine particles fine and from the viewpoint of having high solubility in the monomer (a) and narrowing the particle size distribution, the polymer (B) is preferably incompatible with polyamide but has high affinity. In other words, regarding the affinity between the monomer (A)/the polymer (B) and the affinity between the polymer (B)/the polyamide, the solubility parameter (hereinafter referred to as SP value) is represented by delta_A、δ_B、δ_PA(J^1/2/cm^3/2) When the monomer (A) and the polymer (B) are capable of passing through the square of the difference in their solubility parameters, i.e., (delta)_A-δ_B)²It is stated that the square of the difference in solubility parameter between the polymer (B) and the polyamide, i.e., (delta)_PA-δ_B)²And (4) showing. The closer to zero the higher the affinity, the easier it is to dissolve and compatibilize, but due to the delta of the monomer (A) with the polyamide_AAnd delta_PAOn the other hand, (δ) is preferred from the viewpoint that the polyamide is less likely to form aggregates and the polymer (B) is prevented from being insoluble in the monomer (a) to form aggregates_A-δ_B)²The range of 0.1 to 25 is satisfied. (delta_A-δ_B)²The lower limit of (b) is more preferably 0.3 or more, still more preferably 0.5 or more, and particularly preferably 1 or more. (delta_A-δ_B)²The upper limit of (b) is more preferably 16 or less, still more preferably 12 or less, particularly preferably 10 or less, and most preferably 7 or less. On the other hand, (δ) is preferable from the viewpoint of preventing the polymer (B) from being uniformly compatible and the polyamide fine particles from being obtained, and on the other hand, from the viewpoint of preventing the polymer (B) from being incompatible and the polyamide from being aggregated_PA-δ_B)²The range of 0.1 to 16 is satisfied. (delta_PA-δ_B)²The lower limit of (b) is more preferably 0.3 or more, still more preferably 0.5 or more, and particularly preferably 1 or more. (delta_PA-δ_B)²The upper limit of (d) is more preferably 12 or less, still more preferably 10 or less, particularly preferably 7 or less, and most preferably 4 or less.

The SP value is a value calculated from the cohesive energy density and molar volume of Hoftyzer-Van Krevelen described in Properties of Polymers 4th Edition (D.W. Van Krevelen, published by Elsevier Science, 2009), Chapter7, P215. When it is impossible to calculate by the method, it represents a value calculated from the cohesive energy density and molar volume of Fedors described in chapter P195. When 2 or more monomers (a) and polymers (B) are used, the sum of the products of the SP values and the mole fractions is represented.

Specific examples of such a polymer (B) include polyethylene glycol, polypropylene glycol, poly-1, 4-butanediol, poly-1, 5-pentanediol, poly-1, 6-hexanediol, a polyethylene glycol-polypropylene glycol copolymer, a polyethylene glycol-poly-1, 4-butanediol copolymer, and alkyl ethers in which hydroxyl groups at one or both ends are blocked with methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, and alkylphenyl ethers in which hydroxyl groups are blocked with octylphenyl. In particular, from the viewpoint of excellent compatibility with the polyamide monomer (a) and narrowing the particle size distribution of the polyamide fine particles to be obtained, polyethylene glycol-polypropylene glycol copolymers, polypropylene glycol, poly-1, 4-butanediol, and alkyl ethers thereof are preferable, and from the viewpoint of excellent compatibility with water used as a solvent by ring-opening polymerization of the polyamide monomer (a) by hydrolysis, polyethylene glycol and polyethylene glycol-polypropylene glycol copolymers are more preferable, and polyethylene glycol is most preferable. They may be used in combination of 2 or more without departing from the scope of the present invention.

From the viewpoint of narrowing the particle diameter and particle size distribution of the polyamide fine particles to be obtained and preventing the viscosity of the homogeneous solution from becoming too high and the polymerization reaction rate of the polyamide from becoming extremely slow, the upper limit of the weight average molecular weight of the polymer (B) is preferably 500,000, more preferably 100,000 or less, and still more preferably 50,000 or less. From the viewpoint of preventing excessive improvement in the compatibility between the polymer (B) and the polyamide and making it difficult to form polyamide microparticles, the weight average molecular weight of the polymer (B) is preferably 500 or more, more preferably 1,000 or more, and even more preferably 2,000 or more.

The weight average molecular weight of the polymer (B) is a weight average molecular weight in terms of polyethylene glycol, which is a value measured by gel permeation chromatography using water as a solvent. When the polymer (B) is insoluble in water, it represents a weight average molecular weight in terms of polystyrene, which is a value measured by gel permeation chromatography using tetrahydrofuran as a solvent.

The polyamide fine particles are produced by mixing the monomer (a) and the polymer (B) to obtain a homogeneous solution, and then starting polymerization at a temperature higher than the crystallization temperature of the polyamide obtained by polymerizing the monomer (a). In this case, since the polyamide fine particles are homogeneously formed without crystallization as the monomer (a) is converted into polyamide in the homogeneous mixed solution, it is considered that polyamide fine particles having a regular sphere, a smooth surface, a fine particle size distribution, and a narrow particle size distribution are precipitated after polymerization.

The mass ratio of the monomer (a) to the polymer (B) in the polymerization is preferably 5/95 to 80/20 from the viewpoint of the moderate polymerization rate, the occurrence of phase separation induced together with the polymerization, and the smooth occurrence of particle formation, and the prevention of the formation of a large amount of aggregates or the like due to the particle formation occurring from the early stage of the polymerization. The lower limit of the mass ratio of the monomer (a)/the polymer (B) is more preferably 10/90, still more preferably 20/80, and most preferably 30/70. On the other hand, the upper limit of the mass ratio of the monomer (a)/the polymer (B) is preferably 70/30, more preferably 60/40, and particularly preferably 50/50.

As a method for polymerizing the monomer (A) to form a polyamide, a known method can be used. This method depends on the type of the monomer (A), but in the case of lactams, the following methods are generally used: anionic ring-opening polymerization using an alkali metal such as sodium or potassium, an organic metal compound such as butyllithium or butylmagnesium, or the like as an initiator, cationic ring-opening polymerization using an acid as an initiator, hydrolysis type ring-opening polymerization using water or the like, or the like. In order to be able to polymerize at a temperature equal to or higher than the crystallization temperature of polyamide from which polyamide fine particles having a regular spherical shape and a smooth surface can be easily obtained, cationic ring-opening polymerization and hydrolysis-type ring-opening polymerization are preferable, and hydrolysis-type ring-opening polymerization is more preferable from the viewpoint of suppressing coloration of polyamide by an initiator, gelation by a crosslinking reaction, and a decomposition reaction in polymerization at a temperature equal to or higher than the crystallization temperature of the obtained polyamide. The method of ring-opening polymerization of lactams by hydrolysis is not limited as long as it is a known method, but is preferably a method of producing an amino acid while promoting hydrolysis of lactams under pressure in the presence of water, and then performing ring-opening polymerization and polycondensation while removing water.

In this case, the polycondensation reaction does not occur if water is present, and therefore the polymerization starts while discharging water out of the system of the reaction tank. Therefore, the amount of water used is not particularly limited as long as hydrolysis of the lactam proceeds, but it is generally preferable to make the amount of water used 100 parts by mass or less, provided that the total amount of the monomer (a) and the polymer (B) is 100 parts by mass. In order to improve the production efficiency of the polyamide microparticles, the amount of water used is more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, and particularly preferably 30 parts by mass or less. The lower limit of the amount of water used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more, in order to prevent the hydrolysis reaction of the lactam from proceeding. As a method for removing water (water of condensation) generated by condensation in polycondensation, a known method such as a method of removing inert gas such as nitrogen gas under normal pressure or a method of removing water under reduced pressure can be suitably used.

When the monomer (a) is an amino acid, a dicarboxylic acid, a diamine, or a salt thereof, a polycondensation reaction can be used as a polymerization method. On the other hand, in the case of these monomers (a), there is a combination that does not dissolve uniformly with the polymer (B). In such a monomer (a) and a polymer (B), polyamide fine particles can be produced by further adding a solvent (C) for the monomer (a) and the polymer (B).

The solvent (C) is not particularly limited as long as it is within the above range, and water is most preferable from the viewpoint of dissolving the monomer (a) and the polymer (B) and the same point of view as the water of condensation which is required to be discharged to the outside of the system to cause the polycondensation reaction.

Specifically, when an amino acid such as aminocaproic acid or aminododecanoic acid is used as the monomer (a), or a dicarboxylic acid such as adipic acid and 1, 6-hexanediamine and a diamine are used as the monomer (a), a polyethylene glycol-polypropylene glycol copolymer, and alkyl ethers thereof are added as the polymer (B), and water is added as the solvent (C), thereby forming a uniform solution at the temperature at which polymerization is started. Then, the water of the solvent (C) and the condensed water generated by the progress of polycondensation are discharged to the outside of the reaction tank, whereby polyamide fine particles can be produced while the polymerization is being carried out. In this case, the amount of water used as the solvent (C) is preferably 10 to 200 parts by mass, assuming that the total amount of the amino acid, or dicarboxylic acid and diamine, and the polymer (B) is 100 parts by mass. The amount of water used is more preferably 150 parts by mass or less, and still more preferably 120 parts by mass or less, from the viewpoint of preventing coarsening of the particle diameter. On the other hand, the amount of water used is more preferably 20 parts by mass or more, and still more preferably 40 parts by mass or more, from the viewpoint of ensuring the function as a solvent.

The lactam compound may be used in combination with 2 or more kinds of amino acids and/or dicarboxylic acids, and diamines, but in this case, water acts as a hydrolysis reaction or as a solvent (C).

The polymerization temperature is not particularly limited as long as the polymerization of the polyamide proceeds, but it is preferably a temperature equal to or higher than the crystallization temperature of the polyamide to be obtained, from the viewpoint of bringing the polyamide having a high crystallization temperature closer to a normal sphere and controlling the shape of the surface to be smooth. The polymerization temperature is more preferably +15 ℃ or higher of the crystallization temperature of the polyamide to be obtained, still more preferably +30 ℃ or higher of the crystallization temperature of the polyamide to be obtained, and particularly preferably +45 ℃ or higher of the crystallization temperature of the polyamide to be obtained. From the viewpoint of preventing the occurrence of side reactions, coloration, deterioration of the polymer (B), and the like of the polyamide such as a 3-dimensional crosslinked product, the polymerization temperature is preferably the melting point of the polyamide to be obtained +100 ℃ or lower, more preferably the melting point of the polyamide to be obtained +50 ℃ or lower, still more preferably the melting point of the polyamide to be obtained +20 ℃ or lower, particularly preferably polymerization at the same temperature as the melting point of the polyamide to be obtained, and most preferably the melting point of the polyamide to be obtained-10 ℃ or lower.

The crystallization temperature of the polyamide constituting the polyamide fine particles is a temperature at which the temperature is raised from 30 ℃ at a rate of 20 ℃/min to a temperature 30 ℃ higher than an endothermic peak indicating a melting point of the polyamide in a nitrogen atmosphere by a DSC method, and then the polyamide is held for 1 minute, and the temperature is cooled at a rate of 20 ℃/min to a peak of an exothermic peak occurring in the course of 30 ℃. The temperature at the top of the endothermic peak at which the temperature was raised at 20 ℃/min after the cooling was once set to the melting point of the polyamide fine particles.

The polymerization time can be appropriately adjusted depending on the molecular weight of the polyamide fine particles to be obtained, but is preferably in the range of 0.1 to 70 hours in general from the viewpoint of ensuring the polymerization and obtaining polyamide fine particles while preventing the occurrence of side reactions, coloration, deterioration of the polymer (B), and the like of the polyamide such as a 3-dimensional crosslinked product. The lower limit of the polymerization time is more preferably 0.2 hours or more, still more preferably 0.3 hours or more, and particularly preferably 0.5 hours or more. The upper limit of the polymerization time is more preferably 50 hours or less, still more preferably 25 hours or less, and particularly preferably 10 hours or less.

The polymerization accelerator may be added within a range not to impair the effects of the present invention. As the accelerator, known accelerators can be used, and examples thereof include inorganic phosphorus compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, polyphosphoric acid, and alkali metal salts and alkaline earth metal salts thereof. More than 2 kinds of them can be used. The amount of addition may be appropriately selected, but is preferably 1 part by mass or less based on 100 parts by mass of the monomer (A).

Other additives may be added, and examples thereof include a surfactant for controlling the particle diameter of the polyamide fine particles, a dispersant, an antioxidant for modifying the characteristics of the polyamide fine particles and improving the stability of the polymer (B) to be used, a heat stabilizer, a weather resistant agent, a lubricant, a pigment, a dye, a plasticizer, an antistatic agent, a flame retardant, and the like. More than 2 kinds of them can be used. Further, for the purpose of modifying the monomer (A) and the polyamide and for the purpose of modifying the polymer (B), 2 or more different substances may be used. The amount of addition may be appropriately selected, but is preferably 1 part by mass or less based on 100 parts by mass of the total of the monomer (A) and the polymer (B).

In the present invention, since the polyamide fine particles are induced homogeneously from the homogeneous solution, fine particles can be produced without stirring, but stirring may be performed in order to make the particle size control and the particle size distribution more uniform. As the stirring device, known devices such as a stirring blade, a melt kneader, and a homogenizer can be used, and examples of the stirring blade include a propeller, a paddle, a flat type, a turbine, a cone, an anchor, a screw, and a screw type. The stirring speed depends on the type and molecular weight of the polymer (B), but is preferably in the range of 0 to 2,000rpm from the viewpoint of uniform heat transfer even in a large-sized apparatus and prevention of change in mixing ratio due to adhesion of liquid to a wall surface. The lower limit of the stirring speed is more preferably 10rpm or more, further preferably 30rpm or more, and particularly preferably 50rpm or more, and the upper limit of the stirring speed is more preferably 1,600rpm or less, further preferably 1,200rpm or less, and particularly preferably 800rpm or less.

In order to isolate the polyamide fine particles from the mixture of the polyamide fine particles and the polymer (B) after completion of the polymerization, there may be mentioned a method of isolating the mixture at the time of completion of the polymerization after discharging the mixture in a poor solvent for the polyamide fine particles, a method of isolating the mixture after adding a poor solvent for the polyamide fine particles to a reaction vessel, and the like. From the viewpoint of preventing the polyamide fine particles from being fused with each other and from adhering to each other and from expanding the particle size distribution, a method of separating the polyamide fine particles by discharging the poor solvent of the mixture after cooling the mixture to a temperature not higher than the melting point of the polyamide fine particles, more preferably not higher than the crystallization temperature, a method of separating the polyamide fine particles by adding the poor solvent of the polyamide fine particles to the reaction vessel, and the like are preferable, and a method of separating the polyamide fine particles by adding the poor solvent of the polyamide fine particles to the reaction vessel is more preferable. As the isolation method, a known method such as reduced pressure, pressure filtration, decantation, centrifugation, spray drying, etc. can be appropriately selected.

The poor solvent for the polyamide fine particles is preferably a solvent in which the monomer (a) and the polymer (B) are further dissolved without dissolving the polyamide. Such a solvent may be appropriately selected, but is preferably an alcohol such as methanol, ethanol, or isopropyl alcohol, or water.

The washing, isolation and drying of the polyamide fine particles can be carried out by a known method. As a washing method for removing the adherent substance and the inclusion on the polyamide fine particles, slurry washing or the like can be used, and heating can be appropriately performed. The solvent used for washing is not limited as long as it dissolves the monomer (a) and the polymer (B) without dissolving the polyamide fine particles, and methanol, ethanol, isopropanol, and water are preferred from the viewpoint of economy, and water is most preferred. The isolation may be carried out by appropriately selecting reduced pressure, pressure filtration, decantation, centrifugation, spray drying, etc. The drying is preferably performed at a temperature lower than the melting point of the polyamide fine particles, and may be performed under reduced pressure. Air drying, hot air drying, heating drying, drying under reduced pressure, freeze drying, etc.

Although polyamide microparticles are produced by the above-described method, in particular, in the present invention, polyamide microparticles having a high crystallization temperature, which have been difficult to produce so far, can be produced in a regular spherical shape and a smooth surface shape with a uniform particle diameter.

The polyamide having a high crystallization temperature constituting the polyamide fine particles of the present invention means a crystalline polyamide having a crystallization temperature of 150 ℃ or higher. The crystallization temperature of the polyamide is preferably 160 ℃ or higher, more preferably 170 ℃ or higher, and still more preferably 180 ℃ or higher, from the viewpoint of increasing the melting point, chemical resistance, and the like due to crystallinity and increasing the heat resistance of the polyamide. From the viewpoint of preventing the shape from becoming porous, the crystallization temperature of the polyamide is preferably 300 ℃ or lower, more preferably 280 ℃ or lower, and particularly preferably 260 ℃ or lower.

Specifically, the polyamide-based polyamide composition includes polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), polytetramethylene adipamide (polyamide 46), polytetramethylene adipamide (polyamide 410), polypentylglycol adipamide (polyamide 56), polypentylglycol adipamide (polyamide 510), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecanoamide (polyamide 612), polyhexamethylene adipamide (polyamide 106), polyhexamethylene adipamide (polyamide 126), polyhexamethylene terephthalamide (polyamide 6T), polyparadecanediamide (polyamide 10T), polycaprolactam/polyhexamethylene adipamide copolymer (polyamide 6/66), and the like, and preferably polycaprolactam (polyamide 6), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide 610), and the like, Polyhexamethylene dodecanediamide (polyamide 612), polyhexamethylene adipamide (polyamide 106), polyhexamethylene adipamide (polyamide 126), polycaprolactam/polyhexamethylene adipamide copolymer (polyamide 6/66), more preferably polycaprolactam (polyamide 6), polyhexamethylene adipamide (polyamide 66), polycaprolactam/polyhexamethylene adipamide copolymer (polyamide 6/66).

The polyamide fine particles of the present invention have a number average particle diameter in the range of 0.1 to 100 μm. If the number average particle diameter exceeds 100. mu.m, the surface of the coating film made of the particles becomes inhomogeneous. The number average particle diameter of the polyamide fine particles is preferably 80 μm or less, more preferably 60 μm or less, still more preferably 50 μm or less, and particularly preferably 30 μm or less. If the number average particle diameter is less than 0.1. mu.m, aggregation of particles occurs. The number average particle diameter of the polyamide fine particles is preferably 0.3 μm or more, more preferably 0.7 μm or more, still more preferably 1 μm or more, particularly preferably 2 μm or more, and most preferably 3 μm or more.

The polyamide fine particles in the present invention have a particle size distribution index of 3.0 or less. If the particle size distribution index exceeds 3.0, the fluidity is poor in the application to paints and cosmetics, and the homogeneity of the coating film surface is impaired. The particle size distribution index is preferably 2.0 or less, more preferably 1.5 or less, still more preferably 1.3 or less, and most preferably 1.2 or less. The lower limit is theoretically 1.

The number average particle diameter of the polyamide fine particles can be calculated by optionally specifying 100 particle diameters from a scanning electron micrograph and obtaining the arithmetic mean of the specified particle diameters. In the above photograph, when the particles are not in a perfect circle shape, that is, when the particles are in an elliptical shape, the maximum diameter of the particles is defined as the particle diameter. For accurate measurement of the particle diameter, the measurement is carried out at a magnification of at least 1,000 times, preferably 5,000 times or more. Further, as for the particle diameter distribution index, the value of the particle diameter obtained by the above is determined based on the following numerical conversion formula.

[ number 1]

In addition, Di: particle diameter of each particle, n: determination numbers 100, Dn: number average particle diameter, Dv: volume average particle diameter, PDI: particle size distribution index.

The polyamide fine particles of the present invention have a smooth surface shape in addition to the regular spherical shape, and therefore can impart good sliding properties and fluidity to cosmetics and paints.

The polyamide fine particles have a sphericity of 90 or more. If the positive sphericity is less than 90, a smoother touch cannot be provided in the use of cosmetics and paints. The positive sphericity is preferably 95 or more, more preferably 97 or more, and still more preferably 98 or more. The upper limit value is 100.

The sphericity of the polyamide fine particles is determined by the following numerical expression from the short diameter and long diameter of 30 particles optionally observed from a scanning electron micrograph.

[ number 2]

In addition, S: positive sphericity, a: major axis, b: minor axis, n: number 30 was measured.

The smoothness of the polyamide particle surface can be expressed by the amount of linseed oil absorbed by the polyamide particles. That is, the smoother the surface, the more fine particles having no pores on the surface, and the less the linseed oil absorption amount, which indicates the absorption amount of linseed oil. The linseed oil absorption of the polyamide microparticles of the present invention is 100mL/100g or less. If the linseed oil absorption of the polyamide fine particles exceeds 100mL/100g, good fluidity cannot be provided to cosmetics and paints. The linseed oil absorption of the polyamide microparticles is preferably 90mL/100g or less, more preferably 80mL/100g or less, still more preferably 70mL/100g or less, and particularly preferably 60mL/100g or less. The lower limit of the oil absorption of linseed oil is more than 0mL/100 g.

Further, the linseed oil absorption was measured by the refined あ ま に oil method (pigment test method refined linseed oil method) "according to JIS K5101" pigment test test method of japanese industrial standard (JIS standard).

The smoothness of the surface can also be expressed by the BET specific surface area by gas adsorption, and the smoother the surface, the smaller the BET specific surface area. Specifically, it is preferably 10m²A ratio of the total amount of the compound to the total amount of the compound is 5m or less²A total of 3m or less, preferably²A specific ratio of 1m or less per gram²A ratio of less than g, most preferably 0.5m²The ratio of the carbon atoms to the carbon atoms is less than g.

The BET specific surface area is measured in accordance with JIS R1626 (JIS specification), "specific surface area measurement by gas adsorption BET method に よ る" (method for measuring specific surface area by gas adsorption BET method) ".