JP5192128B2 - Method for producing spherical thermoplastic resin particles - Google Patents

Description

  The present invention relates to a method for producing spherical thermoplastic resin particles.

  Spherical thermoplastic resin particle powder is used for cosmetics such as foundation, antiperspirant, scrub agent, matting agent for coating, anti-blocking material, slipperiness agent, additive for light diffusing agent, etc. Widely used. In particular, polyolefin resin powders such as polyethylene and nylon resin powders have characteristics such as excellent slipperiness and heat resistance, and are widely used.

As a method for producing spherical thermoplastic resin particle powder, a raw material resin and components incompatible with the raw material resin are melt-mixed at a temperature higher than the melting temperature of each other, and then cooled to obtain a spherical thermoplastic resin powder (patent) Reference 1) or a mixture of a polyolefin resin and a fluid that does not dissolve the polyolefin resin at room temperature and normal pressure is heated and / or pressurized to bring at least one component of the fluid into a supercritical state or a subcritical state. Thereafter, a method of lowering the temperature of the fluid and releasing the pressure is known. However, in the case of Patent Document 1, there is a description that a particle size of about 0.01 to 100 microns can be obtained. Are difficult to obtain, and have a wide particle size distribution. Patent Document 2 is also limited to a particle size of about several microns to 100 microns, and is not an easy manufacturing method because it is necessary to maintain the reaction vessel in a supercritical state. On the other hand, the present applicant uses a solvent that is incompatible with the raw resin powder as a medium, and an inorganic dispersant having a particle size of 1 micron or less that is inert to the solvent and the raw resin powder with respect to 100 parts by weight of the raw resin powder. There is disclosed a method for producing a spherical thermoplastic resin powder that is present in an amount of 3 parts by weight or more and 100 parts by weight or less, heated and stirred above the melting temperature of the raw resin powder, and then cooled. (Refer to Patent Document 3) In this production method, when water or propylene glycol is used as a solvent that is not compatible with the raw material resin powder, spherical particles can be obtained satisfactorily, but many inorganic dispersants are used. If a long time is required for the filtration / washing process, or if this solvent is used repeatedly, aggregates may be produced during spheroidization, which is not an industrially advantageous method.
JP 60-192728 A JP 2004-143404 A Japanese Patent Laid-Open No. 62-280226

  An object of the present invention is to provide an industrially advantageous method for producing spherical thermoplastic resin particles that can reduce the amount of hydrophobic silica fine particles added to a dispersion medium and can be used repeatedly.

  The present invention provides a water content in which an amorphous thermoplastic resin powder is dispersed in an amount of 0.1 parts by weight or more and less than 3 parts by weight of hydrophobic silica fine particles in 100 parts by weight of the amorphous thermoplastic resin powder in a polyhydric alcohol. The present invention relates to a method for producing spherical thermoplastic resin particles, characterized by being dispersed in 10% by weight or less of a dispersion medium, heated and stirred at a melting temperature or higher of the amorphous thermoplastic resin powder, and then cooled.

  According to the present invention, it is possible to obtain various spherical thermoplastic resin particles by an industrially more advantageous method because the amount of hydrophobic silica fine particles added to the dispersion medium is reduced and the dispersion medium can be used repeatedly. it can.

  The amorphous thermoplastic resin powder used in the present invention is not particularly limited as long as it is an amorphous powder of thermoplastic resin. Examples of a method for producing these powders include a method of directly obtaining an amorphous resin powder at the time of polymerization, or a method of pulverizing a resin pellet once obtained by a mechanical pulverization method, a freeze pulverization method, or the like.

  The type of the thermoplastic resin is not particularly limited as long as it has thermoplasticity, but examples of typical thermoplastic resins include polyolefin resins, nylon resins, and polyester resins.

  Examples of the polyolefin resin include a polyolefin resin and a copolymer resin of an olefin and another monomer.

  Examples of the polyolefin resin include olefin homopolymers, copolymers, and acid-modified polymers thereof. Examples of olefin homopolymers include polyethylene and polypropylene. Examples of the olefin copolymer include ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-octene copolymer, and ethylene-1-hexene copolymer. Examples of the olefin homopolymer or copolymer acid-modified polymer include maleic anhydride-modified polyethylene and maleic anhydride-modified polypropylene.

  It does not specifically limit as an olefin which comprises the copolymer resin of the said olefin and another monomer, For example, ethylene, propylene, etc. can be mentioned. On the other hand, the other monomer is not particularly limited as long as it is a monomer copolymerizable with the olefin. For example, vinyl ester, α, β-unsaturated carboxylic acid, α, β-unsaturated carboxylic acid anhydride, α , Β-unsaturated carboxylic acid metal salts and α, β-unsaturated carboxylic acid esters. As vinyl ester, vinyl acetate etc. can be mentioned, for example. Examples of the α, β-unsaturated carboxylic acid include (meth) acrylic acid. Examples of the α, β-unsaturated carboxylic acid anhydride include maleic anhydride, and examples of the metal salt of the α, β-unsaturated carboxylic acid include sodium salt and magnesium salt of (meth) acrylic acid. Can be mentioned. Furthermore, examples of the α, β-unsaturated carboxylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, and glycidyl (meth) acrylate. These olefins and other monomers may be used alone or in combination of two or more.

  Specific examples of such copolymer resins of olefin and other monomers include, for example, ethylene / vinyl acetate copolymer, partially saponified ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer. Polymer, ethylene / maleic anhydride copolymer, propylene / maleic anhydride copolymer; ethylene / methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, ethylene / methyl acrylate copolymer, ethylene / Ethylene acrylate copolymer, ethylene / (meth) acrylic ester copolymer such as ethylene / glycidyl (meth) acrylate copolymer; ethylene such as ethylene / glycidyl (meth) acrylate / methyl (meth) acrylate copolymer / (Meth) acrylic ester / (meth) acrylic ester copolymer; ethylene / Ethylene such as lysidyl (meth) acrylate / vinyl acetate copolymer / (meth) acrylic ester / vinyl acetate copolymer and ethylene / (meth) such as ethylene / (meth) acrylic acid methyl / maleic anhydride copolymer Examples thereof include acrylic acid ester / maleic anhydride copolymers and resins of these metal salts.

Examples of the nylon resin include — [NH (CH ₂ ) ₅ CO] —, — [NH (CH ₂ ) ₆ NHCO (CH ₂ ) ₄ CO] —, and — [NH (CH ₂ ) ₆ NHCO (CH ₂ ) Nylon resin having at least one selected from the group consisting of ₈ CO]-,-[NH (CH ₂ ) ₁₀ CO]-and-[NH (CH ₂ ) ₁₁ CO]-as a structural unit Can do. Specific examples thereof include 6 nylon, 66 nylon, 11 nylon, 12 nylon, 6/66 copolymer nylon, 6/10 copolymer nylon, 6/11 copolymer nylon, 6/12 copolymer nylon, 6/66. / 10 copolymer nylon, 6/66/11 copolymer nylon, 6/66/12 copolymer nylon, 6/66/11/12 copolymer nylon, 6/66/10/11/12 copolymer nylon and the above Examples thereof include polyamide elastomer that is a copolymer of polymerized nylon and polyester or polyalkylene ether glycol.

  Examples of the polyester resin include an acid component containing terephthalic acid and isophthalic acid, and a diol component containing ethylene glycol, butylene glycol, diethylene glycol, polyethylene glycol, 1,4-butanediol, and 1,6-hexanediol. Mention may be made of polyester resins obtained by polycondensation reactions. Specific examples thereof include terephthalic acid / ethylene glycol copolymer polyester resin, terephthalic acid / butylene glycol copolymer polyester resin, terephthalic acid / isophthalic acid / 1,4-butanediol copolymer polyester resin, terephthalic acid / isophthalic acid / 1,6-hexanediol copolymer polyester resin, terephthalic acid / isophthalic acid / polyethylene glycol copolymer polyester resin, terephthalic acid / isophthalic acid / ethylene glycol / 1,4-butanediol copolymerized polyester resin, terephthalic acid / isophthalic acid / Examples thereof include adipic acid / 1,4-butanediol copolymer polyester resin and terephthalic acid / isophthalic acid / 1,4-butanediol / diethylene glycol copolymer polyester resin. Moreover, as said polyester-type resin, the polyester-type thermoplastic elastomer which is a copolymer of the said copolyester resin and polyalkylene ether glycol is mentioned.

  In the present invention, the polyolefin resin, nylon resin, and polyester resin may be used alone or in admixture of two or more.

  Among these resins, polyethylene, polypropylene, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer are preferred from the viewpoint of obtaining inexpensive and highly versatile spherical thermoplastic resin particles. Mention may be made of coalescence, ethylene / (meth) acrylic acid ester copolymers and 12 nylon.

  The median particle size of the amorphous thermoplastic resin powder is not particularly limited, but is preferably 1 micron to 3000 microns. If it is smaller than 1 micron, spherical particles can be obtained, but post-processing such as filtration is difficult, and it may be difficult to use industrially. If it exceeds 3000 microns, it may take a long time to spheroidize.

  In the amorphous thermoplastic resin powder used in the present invention, inorganic pigments such as carbon black, titanium oxide, iron oxide and silica, metal powders such as iron, copper, nickel and cobalt, ultraviolet absorbers, heat stabilizers, etc. Organic substances can also be included.

  The polyhydric alcohol used in the present invention may be any polyhydric alcohol that does not substantially swell or dissolve the resin powder used, such as ethylene glycol, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoacetate, polyethylene glycol, Examples include methoxyethanol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoacetate, polypropylene glycol, and glycerin. In the present invention, the polyhydric alcohols may be used alone or in combination of two or more. Among these, at least one selected from the group consisting of ethylene glycol, propylene glycol, polyethylene glycol and polypropylene glycol is particularly preferable.

  The amount of polyhydric alcohol used is preferably 50 to 2000 parts by weight with respect to 100 parts by weight of the amorphous thermoplastic resin powder. If the amount used is less than 50 parts by weight, the resin concentration is too high and it is difficult to sufficiently stir and mix. Using more than 2000 parts by weight is not preferable because the production amount is smaller than the size of the apparatus.

  As the hydrophobic silica fine particles used in the present invention, for example, those obtained by hydrophobizing hydrophilic silica fine particles with a hydrophobic compound are used. Specifically, the surface of hydrophilic silica fine particles is coated with a hydrophobic compound, and the surface of hydrophilic silica fine particles is chemically bonded with a hydrophobic compound having a hydrophobic group in the molecule to a silanol group. Can be mentioned.

  The method for hydrophobizing the hydrophilic silica fine particles is not particularly limited, and the hydrophilic silica fine particles are immersed in a solution of the hydrophobic compound and then dried and heat-treated, or the powder of the hydrophilic silica fine particles is stirred. What is necessary is just to perform by well-known methods, such as the method of spraying the solution of a hydrophobic compound, drying, and heat-processing.

  As the hydrophilic silica fine particles used for the hydrophobization treatment, normal hydrophilic silica fine particles such as fused silica, white carbon obtained by a dry method or a wet method can be used.

  Examples of the hydrophobic compound used for the hydrophobizing treatment include silicone compounds, silane compounds, metal soaps, waxes, and the like, among which silicone compounds and silane compounds are preferably used. Examples of the silicone compound include octamethylcyclotetrasiloxane, dimethylpolysiloxane, methylhydrogenpolysiloxane, and silicone oil such as modified dimethylpolysiloxane having an amino group or an epoxy group introduced at the side chain or terminal. It is done. Examples of the silane compound include silane compounds such as methacryloxysilane, methylchlorosilane, and dimethyldichlorosilane, and alkoxysilanes such as methylalkoxysilane, phenylalkoxysilane, isobutylalkoxysilane, hexylalkoxysilane, octylalkoxysilane, and decylalkoxysilane. Examples thereof include compounds and silazane compounds such as hexamethyldisilazane.

  In the present invention, the hydrophobic silica fine particles may be used alone or in admixture of two or more.

  In the present invention, the average particle diameter of the hydrophobic silica fine particles is not particularly limited as long as it adheres to the surface of the amorphous thermoplastic resin powder particles in the dispersion medium and can prevent fusion between the particles, but the amorphous thermoplastic resin to be used is not limited. In relation to the powder, it is often preferable to use hydrophobic silica fine particles having an average particle diameter of 0.001 to 0.5 microns. Silica fine particles having an average particle size of less than 0.001 microns are difficult to obtain. On the other hand, when larger than 0.5 micron, the possibility of aggregation between the amorphous thermoplastic resin powder particles increases.

  The amount of the hydrophobic silica fine particles used varies depending on the combination of the amorphous thermoplastic resin powder and the polyhydric alcohol, but it is 0.1 parts by weight or more and less than 3 parts by weight with respect to 100 parts by weight of the amorphous thermoplastic resin powder. Good results can be obtained by using 0.5 to 2.8 parts by weight. When the amount is less than 0.1 part by weight, the thermoplastic resin particles may be aggregated during spheroidization and good spherical particles may not be obtained. On the other hand, when 3 parts by weight or more is used, spheroidization is possible, but it takes a long time for filtration and washing, which may not be industrially advantageous.

  The method for dispersing the hydrophobic silica fine particles in the polyhydric alcohol is not particularly limited as long as it can be uniformly dispersed in the polyhydric alcohol, and a normal propeller type stirrer, homomixer, homojetter, etc. Can be used.

  The water content of the dispersion medium in which the hydrophobic silica fine particles are dispersed is preferably 10% by weight or less, preferably 0.1 to 10% by weight, and more preferably 0.2 to 8% by weight. Although the water content of the dispersion medium may be lower than 0.1% by weight, it is difficult to manage moisture and is not practical. On the other hand, when the dispersion medium is used repeatedly, water may be mixed from the filtration / washing liquid and the water content may be higher than 10% by weight. However, when such a dispersion medium is used, the hydrophobic base portion of the hydrophobic silica fine particles is decomposed. For this reason, a large amount of aggregates may be generated and good spherical particles may not be obtained.

  In the present invention, the amount of hydrophobic silica fine particles used can be reduced by setting the water content of the dispersion medium to 10% by weight or less. That is, when the water content of the dispersion medium is higher than 10% by weight, the hydrophobic group of the hydrophobic silica fine particles is easily decomposed, and the amount of the hydrophobic silica fine particles used is 3 parts by weight with respect to 100 parts by weight of the amorphous thermoplastic resin powder. Although it was necessary as described above, since the hydrophobic group portion is less likely to be decomposed by setting the water content to 10% by weight or less, it becomes possible to produce spherical particles even when the amount of the hydrophobic silica fine particles used is less than 3 parts by weight. It is thought. Further, since the dispersion medium of the present invention is adjusted to have a low water content, it can be used stably even when the dispersion medium is repeatedly used.

  In the present invention, the spheroidization of the amorphous thermoplastic resin powder is not less than the melting temperature of the amorphous thermoplastic resin powder, that is, not less than the temperature at which the resin begins to have fluidity in a dispersion medium that is not compatible with the amorphous thermoplastic resin powder. By stirring with heating. However, raising the temperature more than necessary is not preferable because the hydrophobic group of the resin or hydrophobic silica fine particles may be decomposed. Specifically, the mixture is heated and stirred at a temperature equal to or higher than the melting temperature of the amorphous thermoplastic resin powder, preferably 10 to 50 ° C. from the melting temperature, usually 1 to 60 minutes, preferably 10 to 30 minutes, and then cooled. If necessary, the heating time can be set to 60 minutes or longer, but there is a possibility that the dispersion medium may be deteriorated. After spheronization, the resin is cooled to below the melting temperature of the resin, filtered, washed with water, and dried to obtain the desired spherical thermoplastic resin particle powder.

  In industrial implementation, it is preferable to appropriately select a combination of amorphous thermoplastic resin powder and polyhydric alcohol, and consider that the melting temperature of the resin does not exceed the boiling point of polyhydric alcohol. As long as it can withstand, it is not particularly limited.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Evaluation Method The median particle diameter of the resin particles obtained in Examples and Comparative Examples and the water content of the dispersion medium were measured according to the following methods.
(Medium particle diameter) The intermediate particle diameter of the amorphous thermoplastic resin powder and the obtained spherical resin particles as raw materials are measured by a laser diffraction particle size distribution measuring device (trade name “SALD-2000J” manufactured by Shimadzu Corporation). And measured.
(Water content) The water content in the dispersion medium was measured using a Karl Fischer moisture meter (trade name “AQ-6” of Hiranuma Sangyo Co., Ltd.).

Example 1
A 500 ml four-necked flask was charged with 200 g of propylene glycol and 1.2 g of hydrophobic silica fine particles (product name: Aerosil R972, average particle diameter 0.016 microns) manufactured by Nippon Aerosil Co., Ltd., and mixed with stirring. The water content of the obtained dispersion medium was 0.3% by weight. Thereafter, 50 g of amorphous polyethylene powder (melting temperature 107 ° C., medium particle size 180 microns) was charged, stirred and mixed. Thereafter, the temperature was raised until the internal temperature reached 125 ° C. while stirring was continued. The mixture was stirred for 15 minutes while maintaining the internal temperature at 125 ° C, and then cooled to 60 ° C. After filtration, it was washed with water and dried to obtain spherical polyethylene particles having a median particle size of 175 microns with almost no glassy matter. In the present specification, the glassy material means a resin particle fused to become coarse particles.

Example 2
In a 500 ml four-necked flask, 200 g of ethylene glycol, 0.5 g of hydrophobic silica fine particles (Nippon Aerosil, trade name; Aerosil R972 average particle size 0.016 microns) and 0.5 g of hydrophobic silica fine particles (Nippon Aerosil, trade name; Aerosil R812 (average particle size 0.007 micron) 0.25 g was charged and mixed with stirring. The water content of the obtained dispersion medium was 0.3% by weight. Thereafter, 50 g of amorphous ethylene / acrylic acid copolymer powder (melting temperature: 104 ° C., median particle size: 280 microns) was charged and stirred and mixed. Thereafter, the temperature was raised until the internal temperature reached 140 ° C. while stirring was continued. The mixture was stirred for 15 minutes while maintaining the internal temperature at 140 ° C, and then cooled to 60 ° C. After filtration, it was washed with water and dried to obtain spherical ethylene / acrylic acid copolymer particles having a median particle size of 270 microns with almost no glassy matter.

Example 3
A 500 ml four-necked flask was charged with 200 g of polyethylene glycol 200 (molecular weight 200) and 0.3 g of hydrophobic silica fine particles (product name: Aerosil R805 average particle size 0.012 microns) manufactured by Nippon Aerosil Co., Ltd., and mixed with stirring. The water content of the obtained dispersion medium was 0.3% by weight. Thereafter, 50 g of amorphous ethylene / vinyl acetate copolymer powder (melting temperature: 93 ° C., median particle size: 200 μm) was charged, stirred and mixed. Thereafter, the temperature was raised until the internal temperature reached 130 ° C. while stirring was continued. The mixture was stirred for 15 minutes while maintaining the internal temperature at 130 ° C, and then cooled to 60 ° C. After filtration, it was washed with water and dried to obtain spherical ethylene / vinyl acetate copolymer particles having a median particle diameter of 190 microns with almost no glassy matter.

Example 4
In a 500 ml autoclave, 200 g of polypropylene glycol 1000 (molecular weight 1000) and 1 g of hydrophobic silica fine particles (product name: Aerosil R202 average particle size 0.014 microns) manufactured by Nippon Aerosil Co., Ltd. were stirred and mixed. The water content of the obtained dispersion medium was 0.3% by weight. Thereafter, 50 g of amorphous polypropylene powder (melting temperature: 158 ° C., medium particle size: 300 μm) was charged, stirred and mixed. Thereafter, the temperature was raised until the internal temperature reached 200 ° C. while stirring was continued. The mixture was stirred for 15 minutes while maintaining the internal temperature at 200 ° C, and then cooled to 60 ° C. After filtration, it was washed with water and dried to obtain spherical polypropylene particles having a median particle size of 290 microns with almost no glassy matter.

Example 5
In a 500 ml four-necked flask, 200 g of propylene glycol, 0.5 g of hydrophobic silica fine particles (product name: Aerosil R972, average particle diameter 0.016 microns) and 0.5 g of hydrophobic silica silica fine particles (product name: Nippon Aerosil) Aerosil R805 (average particle size 0.012 micron) 0.9 g was charged and mixed with stirring. The water content of the obtained dispersion medium was 0.3% by weight. Thereafter, 50 g of amorphous ethylene / methyl methacrylate copolymer powder (melting temperature: 100 ° C., median particle size: 300 μm) was charged and mixed with stirring. Thereafter, the temperature was raised until the internal temperature reached 140 ° C. while stirring was continued. The mixture was stirred for 15 minutes while maintaining the internal temperature at 140 ° C, and then cooled to 60 ° C. After filtration, it was washed with water and dried to obtain spherical ethylene / methyl methacrylate copolymer particles having a median particle diameter of 295 microns with almost no glassy matter.

Example 6
In a 500 ml autoclave, 200 g of polyethylene glycol 200 (molecular weight 200) and 1.2 g of hydrophobic silica fine particles (product name: Aerosil R812 average particle size: 0.007 micron) manufactured by Nippon Aerosil Co., Ltd. were stirred and mixed. The water content of the obtained dispersion medium was 0.3% by weight. Thereafter, 50 g of amorphous 12 nylon powder (melting temperature: 178 ° C., median particle size: 200 μm) was charged, stirred and mixed. Thereafter, the temperature was raised until the internal temperature reached 220 ° C. while stirring was continued. The mixture was stirred for 15 minutes while maintaining the internal temperature at 220 ° C, and then cooled to 60 ° C. After filtration, it was washed with water and dried to obtain spherical 12 nylon particles having a median particle diameter of 195 microns with almost no glassy matter.

Example 7
In the same manner as in Example 1, except that the dispersion medium used in Example 1 was repeatedly used three times and a dispersion medium having a water content of 7% by weight due to the mixing of water from the filtered washing water was used. Spherical polyethylene particles having a median particle diameter of 180 microns with almost no particles were obtained.

Example 8
In the same manner as in Example 3, except that the dispersion medium used in Example 3 was repeatedly used twice, and a dispersion medium having a water content of 4% by weight due to mixing of water from the filtered washing water was used. Spherical ethylene / vinyl acetate copolymer particles having a median particle diameter of 190 microns with almost no particles were obtained.

Comparative Example 1
The same operation as in Example 1 was performed except that 2.5 g of hydrophobic silica fine particles were used in Example 1. As a result, the amount of water required for filtration and washing increased, and a long time was required for filtration and washing. The obtained powder was a spherical polyethylene particle having a medium particle diameter of 175 microns with almost no glassy matter.

Comparative Example 2
Except that 0.03 g of hydrophobic silica fine particles were used in Example 1, the same operation as in Example 1 was performed. As a result, aggregated particles were formed during the temperature increase, and spherical polyethylene particles were not obtained.

Comparative Example 3
The same as in Example 1 except that the dispersion medium used in Example 1 was repeatedly used 6 times, and the dispersion medium in which the water content in the dispersion medium was 15% by weight due to the mixing of water from the filtered washing water was used. As a result of the above operation, agglomerates were formed in the course of temperature increase, and spherical polyethylene particles were not obtained.

The spherical thermoplastic resin particles obtained according to the present invention include various cosmetics such as scrub facial cleansers, carriers such as catalysts, additives for printing inks and paints, raw materials for porous bodies, It can be used as a raw material for modeling.

Claims (3)

  The water content of the amorphous thermoplastic resin powder is 10% by weight, in which 0.1 to 3 parts by weight of hydrophobic silica fine particles are dispersed in 100 parts by weight of the amorphous thermoplastic resin powder in polyhydric alcohol. A method for producing spherical thermoplastic resin particles, comprising dispersing in the following dispersion medium, heating and stirring at a temperature equal to or higher than the melting temperature of the amorphous thermoplastic resin powder, and then cooling.   2. The method for producing spherical thermoplastic resin particles according to claim 1, wherein the polyhydric alcohol is at least one selected from the group consisting of ethylene glycol, propylene glycol, polyethylene glycol and polypropylene glycol. The amorphous thermoplastic resin powder is selected from the group consisting of polyethylene, polypropylene, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer, ethylene / (meth) acrylic acid ester copolymer and 12 nylon. The method for producing spherical thermoplastic resin particles according to claim 1 or 2, which is at least one kind.