JP5626952B2 - Method for producing polypropylene fine particles - Google Patents

Description

  The present invention relates to a method for producing spherical polypropylene fine particles having a small particle diameter and a uniform particle diameter, and a polypropylene fine particle.

  Polyolefin particles with the same shape and particle size are used for powder molding materials, sintering molding materials, thermoplastic resins and thermosetting resin fillers, paints, adhesives, lubricants, filter agents, cleaning agents, analytical columns. It is attracting attention as a useful material in a wide range of fields, such as adsorbents for oil, oil absorbents, liquid crystal spacers, toners, catalyst carriers, and cosmetic base materials. Among these, isotactic polypropylene fine particles are expected to be used in a wide range of applications because of their high heat resistance and low cost.

  Conventionally, as a means for obtaining isotactic polypropylene fine particles, there is a method of physically pulverizing a polypropylene resin using a pulverizer or the like. In this method, fine particles can be easily produced at low cost, but the obtained fine particles have an indefinite shape and a large particle size. Furthermore, work such as classification is required to obtain a narrow particle size distribution.

  Moreover, in patent document 1 (Unexamined-Japanese-Patent No. 2004-143404), patent document 2 (Unexamined-Japanese-Patent No. 2007-16219), etc., a polypropylene is mixed and stirred in the water and / or alcohol of a supercritical state or a subcritical state. A method has been proposed. This method requires a container that can withstand high temperatures and pressures in order to obtain supercritical or subcritical water and / or alcohol.

  Further, in Patent Document 3 (Japanese Patent Laid-Open No. 2006-45295), a method of forming fine particles by emulsifying a dispersant ethylene oxide / propylene oxide copolymer and water at or above the melting point of polypropylene (hereinafter also referred to as an emulsification method). ) Is disclosed. On the other hand, in Patent Document 4 (JP-A-5-43624), Patent Document 5 (JP-A-5-43625), and the like, polypropylene fine particles are directly obtained by controlling polymerization conditions using a homogeneous metallocene catalyst. A method is disclosed. However, in these methods, it is very difficult to control the particle shape, and the shape of the fine particles is indefinite.

JP 2004-143404 A (Claims) JP 2007-16219 A (Claims) JP 2006-45295 A (Claims) JP-A-5-43624 (Claims) JP-A-5-43625 (Claims)

  An object of the present invention is to provide spherical polypropylene fine particles having a maximum particle size of 50 μm or less and a narrow particle size distribution. Another object of the present invention is to provide spherical fine particles having a non-smooth particle surface, which can be used, for example, as a scrub facial cleanser and useful as an abrasive.

  In such a situation, as a result of intensive studies, the present inventors dissolved raw material polypropylene in an aliphatic hydrocarbon solvent or alicyclic hydrocarbon solvent at a temperature equal to or higher than the melting point of raw material polypropylene, and then obtained. By cooling the raw material polypropylene solution, it was found that the maximum particle size was 50 μm or less, the particle size distribution was narrow, and spherical polypropylene fine particles were precipitated, and the present invention was completed.

That is, the present onset Ming, aliphatic hydrocarbon compound solvent, the alicyclic hydrocarbon compound solvent or a mixture of these solvents, the raw material polypropylene added, and dissolved by heating at a temperature 10 ° C. or higher than the melting point of the raw material polypropylene And a raw material polypropylene solution preparation step, and a raw material polypropylene solution preparation step and a precipitation step of cooling the raw material polypropylene solution to a temperature range of 0 ° C. or lower to precipitate polypropylene fine particles. A method is provided.

  According to the present invention, it is possible to provide spherical polypropylene fine particles having a maximum particle size of 50 μm or less and a narrow particle size distribution. Furthermore, it is possible to provide spherical fine particles having a non-smooth particle surface that can be used, for example, as a scrub facial cleanser and useful as an abrasive.

2 is a SEM photograph of polypropylene fine particles of Example 1. 4 is a SEM photograph of polypropylene fine particles of Comparative Example 3.

  In the method for producing polypropylene fine particles of the present invention, a raw material polypropylene is added to an aliphatic hydrocarbon compound solvent, an alicyclic hydrocarbon compound solvent, or a mixed solvent thereof and dissolved by heating at a temperature equal to or higher than the melting point of the raw material polypropylene. And a raw material polypropylene solution preparation step for obtaining a raw material polypropylene solution, and a precipitation step for cooling the raw material polypropylene solution to precipitate polypropylene fine particles.

  In the method for producing polypropylene fine particles of the present invention, first, the raw material polypropylene solution preparation step is performed.

  The raw material polypropylene relating to the raw material polypropylene solution preparation step, that is, polypropylene dissolved in a solvent is not particularly limited, but polypropylene having an isotactic structure (isotactic polypropylene) or polypropylene having a syndiotactic structure (syndi) Tactic polypropylene) is preferred, and isotactic polypropylene is particularly preferred. Moreover, the shape of the raw material polypropylene is not particularly limited, and may be powdery or pelletized. Furthermore, the raw material polypropylene may contain additives such as antioxidants, ultraviolet absorbers, lubricants, antistatic agents, flame retardants, fillers, metal deactivators, pigments, dyes, crystal nucleating agents, and the like. In particular, the addition of an antioxidant is preferable in that it can prevent oxidation when the raw material polypropylene is heated.

  A polymerization catalyst and a polymerization method for producing the raw material polypropylene are not particularly limited. For example, magnesium compounds, titanium halide compounds, and electron donating compounds as disclosed in JP-A-63-3010 are disclosed. A method for obtaining a raw material polypropylene using an olefin polymerization catalyst comprising a solid catalyst component, an organoaluminum compound, and an external electron donating compound prepared from dimethylsilyl, as disclosed in JP-A-5-43624, etc. Examples include a method in which methylaluminoxane is added to a homogeneous catalyst such as bis (tetrahydroindenyl) zirconium dichloride and solution polymerization is performed to obtain a raw material polypropylene. The polymerization catalyst may exhibit isospecificity or syndiospecificity, and examples thereof include solid catalysts such as magnesium chloride-supported titanium catalyst, homogeneous transition metal catalysts such as metallocene catalyst, and supported catalysts thereof. . The polymerization method may be any polymerization method that exhibits the isospecificity or syndiospecificity of the polymerization catalyst, and examples thereof include bulk polymerization, slurry polymerization, gas phase polymerization, and polymerization combining them in multiple stages.

  The raw material polypropylene has a melting point due to an isotactic structure or a syndiotactic structure. The melting point of the raw material polypropylene is preferably 130 ° C. or higher, and particularly preferably 150 ° C. or higher, from the viewpoint of good dispersibility of the obtained polypropylene fine particles and narrowing of the particle size distribution.

In the raw material polypropylene, the content of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity is 1.0% by mass or less, preferably 0.1% by mass or less. When the content of the polypropylene having a melting point in the raw material polypropylene of less than 130 ° C. and low stereoregularity is within the above range, it becomes easy to obtain polypropylene fine particles having a narrow particle size distribution and excellent dispersibility. The content of polypropylene having a melting point of less than 130 ° C. and low stereoregularity contained in the raw material polypropylene is measured by the following method. First, a round bottom flask equipped with a stirrer is charged with 2.0 g of polypropylene and 200 mL of decahydronaphthalene and stirred at 180 ° C. for 60 minutes to prepare a uniform solution. The flask is then immediately immersed in a 23 ° C. water bath and the solution is cooled to 23 ° C. After cooling, the precipitated polypropylene is recovered by filtration, dried, and the weight X (g) of the precipitated polypropylene is measured. And the following formula (2):
Y (%) = {(2.0−X) /2.0} × 100 (2)
The content Y (%) of the polypropylene having a melting point lower than 130 ° C. and low stereoregularity is determined. For example, when X = 1.8 g, the content Y (%) of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity is 10%.

  The number average molecular weight (Mn) of the raw material polypropylene is not particularly limited, but is preferably 10,000 or more, particularly preferably 50,000 in that the particle size distribution of the obtained polypropylene fine particles can be narrowed and the dispersibility can be improved. That's it. The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the raw material polypropylene is preferably 7 or less, particularly preferably 3 in that the particle size distribution of the obtained polypropylene fine particles can be narrowed. It is as follows.

  The raw material polypropylene is not particularly limited, and may have a side chain other than a methyl group in the polymer chain. When the raw material polypropylene has a side chain other than a methyl group, the side chain has, for example, a hydrogen atom, an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and a substituent. An alicyclic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, a hydroxyl group, an alkoxy group, a ketone group, a carboxyl group, an ester group, Examples thereof include a carbonate group, an amino group, an amide group, a cyano group, an imino group, a thiol group, and a siloxy group. Examples of the substituent of the aliphatic hydrocarbon group, alicyclic hydrocarbon group and aromatic hydrocarbon group include a hydroxyl group, an alkoxy group, a ketone group, a carboxyl group, an ester group, a carbonate group, an amino group, an amide group, A cyano group, an imino group, a thiol group, a siloxy group, etc. are mentioned. Furthermore, these side chains can be present in the polymer chain of the raw polypropylene in any random, block or alternating chain distribution. The raw material polypropylene may contain a heterogeneous bond structure such as a head-head bond structure, a tail-tail bond structure, or a 1,3-bond structure in the polymer chain.

  The raw material polypropylene having a side chain other than the methyl group is obtained by copolymerization of propylene and a vinyl compound having a substituent corresponding to a side chain other than the methyl group, chemical modification of polypropylene, or the like.

  When the raw material polypropylene is synthesized with a solid catalyst such as a magnesium chloride-supporting titanium catalyst, it contains a very small amount of polypropylene having a melting point of less than 130 ° C. and low stereoregularity. Since such a polypropylene having a melting point of less than 130 ° C. and low stereoregularity has an action of adsorbing and aggregating the fine isotactic polypropylene fine particles, the raw material polypropylene has a melting point of 130 ° C. It is preferable that it does not contain a polypropylene having a low stereoregularity. Therefore, it is preferable to perform a purification step of removing polypropylene having a melting point of less than 130 ° C. and low stereoregularity from the raw material polypropylene before performing the raw material polypropylene solution preparation step.

  There is no particular limitation on the method for carrying out the purification step for removing the low stereoregular polypropylene having a melting point of less than 130 ° C. from the raw material polypropylene. For example, the raw material polypropylene is heated in a hydrocarbon solvent. Then, the solution is cooled to near room temperature to precipitate high isotactic polypropylene, followed by filtration, whereby the precipitated high isotactic polypropylene and the melting point dissolved in the solvent are reduced. The method is performed by fractionating a low stereoregular polypropylene having a temperature lower than 130 ° C. Further, homogeneous transition metal catalysts such as metallocene catalysts and catalysts such as supported catalysts thereof provide homogeneous high isotactic polypropylene or high syndiotactic polypropylene. The process can be omitted. Examples of the hydrocarbon solvent used in the purification step include heptane, octane, decane, dodecane, xylene, decahydronaphthalene, menthane, cyclohexane, methylcyclohexane, ethylcyclohexane, butylcyclohexane, and bicyclohexyl. It is done. Of these hydrocarbon solvents used in the purification step, a hydrocarbon solvent having a boiling point of 160 ° C. or higher is preferable in terms of being able to efficiently fractionate low stereoregular polypropylene, and alicyclic hydrocarbons. Compounds are particularly preferred.

  In the raw material polypropylene preparation step, the solvent for dissolving the raw material polypropylene can exhibit compatibility with the raw material polypropylene by heating at a temperature equal to or higher than the melting point of the raw material polypropylene to dissolve the raw material polypropylene. An aliphatic hydrocarbon compound, an alicyclic hydrocarbon compound, or a mixture of the aliphatic hydrocarbon compound and the alicyclic hydrocarbon compound. In the raw material polypropylene preparation step, the solvent for dissolving the raw material polypropylene is not an aromatic hydrocarbon compound. The aliphatic hydrocarbon compound solvent and the alicyclic hydrocarbon compound solvent may be a saturated hydrocarbon compound or an unsaturated hydrocarbon compound having a double bond. The aliphatic hydrocarbon compound solvent may be a linear hydrocarbon compound or a hydrocarbon compound having a branched chain. The aliphatic hydrocarbon compound solvent or the alicyclic hydrocarbon compound solvent may be a single type or a mixture of two or more types.

  The upper limit of the boiling point of the aliphatic hydrocarbon compound solvent and the alicyclic hydrocarbon compound solvent is not particularly limited, but is usually 250 ° C. or less from the viewpoint of handleability. Moreover, the boiling point of the aliphatic hydrocarbon compound solvent and the alicyclic hydrocarbon compound solvent may be lower than the melting point of the raw material polypropylene. And the boiling point of this aliphatic hydrocarbon compound solvent and this alicyclic hydrocarbon compound solvent becomes like this. Preferably it is 160-250 degreeC. In addition, when using the solvent whose boiling point is below melting | fusing point of this raw material polypropylene, this raw material polypropylene preparation process is performed under pressure.

  The melting point of the aliphatic hydrocarbon compound solvent and the alicyclic hydrocarbon compound solvent may be lower than the softening point (110 ° C.) of polypropylene. For example, when a solvent having a melting point of 50 ° C. is used and cooled to −20 ° C. in the precipitation step, immediately after cooling, the solvent is solidified, but a temperature not lower than the melting point of the solvent and not exceeding the softening point of polypropylene. When heated at, only the solvent is melted, so that the precipitated polypropylene fine particles and the solvent can be separated by filtration or the like. And melting | fusing point of this aliphatic hydrocarbon compound solvent and this alicyclic hydrocarbon compound solvent becomes like this. Preferably it is 30 degrees C or less.

  Specific examples of the aliphatic hydrocarbon compound solvent or the alicyclic hydrocarbon compound solvent are listed below. The temperature in parentheses represents the boiling point of the compound. For example, 2-methylnonane (166 ° C), 3,3-dimethyloctane (161 ° C), 3,4-diethylhexane (162 ° C), 3,5-dimethyloctane (160 ° C), 3-methylnonane (167 ° C) 4,4-dimethyloctane (161 ° C), 4-methylnonane (165 ° C), 5-methylnonane (165 ° C), 2,2,4,6,6-pentamethylheptane (180 ° C), 2-methylundecane (210 ° C), 3-methylundecane (211 ° C), 1-decene (171 ° C), n-butylcyclohexane (180 ° C), cis-1-isopropyl-4-methylcyclohexane (167 ° C), cyclodecane (201 ° C) ), Isobutylcyclohexane (169 ° C.), n-pentylcyclopentane (180 ° C.), tert-butylcyclohexane (17 1 ° C), trans-1-isopropyl-4-methylcyclohexane (170 ° C), 1-undecene (190 ° C), amylcyclohexane (202 ° C), 1-dodecene (213 ° C), hexylcyclohexane (221 ° C), tri Isobutylene (177 ° C), 1,9-decadiene (165 ° C), 1-decyne (174 ° C), 3-decyne (175 ° C), 5-decine (177 ° C), cis-decahydronaphthalene (190 ° C), trans-decahydronaphthalene (185 ° C.), 1,10-undecadiene (187 ° C.), 1-undecyne (195 ° C.), 5-undecyne (197 ° C.), 1,11-dodecadiene (207 ° C.), 6-dodecine ( 209 ° C), bicyclohexyl (239 ° C), (+)-3-carene (170 ° C), (+)-limonene (176 ° C) , (−)-Α-ferrandrene (175 ° C.), (−)-β-pinene (165 ° C.), α-terpinene (173 ° C.), endo-tetrahydrodicyclopentadiene (192 ° C.), γ-terpinene (183) ° C), 1,3-dimethyladamantane (201 ° C), 1-ethyladamantane (229 ° C), 1,8-nonadiyne (162 ° C), tricyclo [6.2.1.0 (2,7)] undeca- 4-ene (209 ° C.), cis, trans, trans-1,5,9-cyclododecatriene (242 ° C.) and other aliphatic hydrocarbon compounds or alicyclic hydrocarbon compounds having a boiling point of 160 ° C. or higher, ethyl Cyclohexane (130 ° C), 2,5-dimethyl-2,4-hexadiene (132 ° C), ethylidenecyclohexane (136 ° C), cis-cyclooctene (145 ° C), 7 Methyl-1,6-octadiene (143 ° C.), 1,8-nonadiene (141 ° C.), isopropylcyclohexane (155 ° C.), 1-nonene (146 ° C.), trans-2-nonene (144 ° C.), 4-nonene (144 ° C), propylcyclohexane (155 ° C), 1,2,4-trimethylcyclohexane (141 ° C), 2,3-dimethylheptane (140 ° C), nonane (151 ° C), 1,5-cyclooctadiene ( 149 ° C.), cyclooctane (149 ° C.), 1-isopropyl-1-cyclohexene (155 ° C.), etc., an aliphatic hydrocarbon compound or alicyclic hydrocarbon compound having a boiling point of 130 ° C. or higher and lower than 160 ° C., 4 -Vinyl-1-cyclohexene (126 ° C), 2,5-dimethyl-1,5-hexadiene (114 ° C), 1,7-octadiene (11 4 ° C), vinylcyclohexane (128 ° C), 1,1-dimethylcyclohexane (118 ° C), 1,2-dimethylcyclohexane (124 ° C), 1,3-dimethylcyclohexane (121 ° C), 1,4-dimethyl Cyclohexane (120 ° C), 2-methyl-2-heptene (122 ° C), 1-octene (122 ° C), trans-2-octene (123 ° C), trans-3-octene (121 ° C), trans-4- Octene (122 ° C), 2,3,4-trimethyl-2-pentene (116 ° C), 2,4,4-trimethyl-1-pentene (101 ° C), 2,4,4-trimethyl-2-pentene ( 104 ° C), 2,2-dimethylhexane (107 ° C), 2,4-dimethylhexane (108 ° C), 2,5-dimethylhexane (108 ° C), 3,4 Dimethylhexane (119 ° C), 3-methylheptane (118 ° C), 4-methylheptane (117 ° C), octane (125 ° C), 2,2,4-trimethylpentane (98 ° C), 1,3-cyclo Heptadiene (120 ° C.), cycloheptene (112 ° C.), 2,4-dimethyl-1,3-pentadiene (94 ° C.), 1,6-heptadiene (89 ° C.), 1-methyl-1-cyclohexene (110 ° C), 4-methyl-1-cyclohexene (101 ° C), methylenecyclohexane (102 ° C), 2-methyl-1,5-hexadiene (92 ° C), norbornane (85 ° C), vinylcyclopentane (97 ° C) ), Cycloheptane (118 ° C.), 4,4-dimethyl-1-pentene (72 ° C.), ethylcyclopentane (103 ° C.), 3-ethyl-2-pentene (9 ° C), 1-heptene (94 ° C), cis-2-heptene (98 ° C), trans-2-heptene (98 ° C), cis-3-heptene (96 ° C), trans-3-heptene (94 ° C) Methylcyclohexane (101 ° C.), 2-methyl-1-hexene (92 ° C.), 2,3,3-trimethyl-1-butene (78 ° C.), 2,3-dimethylpentane (89 ° C.), 2, 4-dimethylpentane (80 ° C), 3,3-dimethylpentane (86 ° C), heptane (98 ° C), 2-methylhexane (90 ° C), 3-methylhexane (91 ° C), 2,2, 3-trimethylbutane (81 ° C.), 1,3-cyclohexadiene (80 ° C.), 1,4-cyclohexadiene (88 ° C.), cyclohexene (83 ° C.), 2,3-dimethyl-1,3-butadiene (68 ° C), 1, 3 -Hexadiene (72 ° C), 1,4-hexadiene (82 ° C), 1,5-hexadiene (60 ° C), 2,4-hexadiene (82 ° C), methylenecyclopentane (75 ° C), trans-2-methyl -1,3-pentadiene (75 ° C.), 2-methyl-1,4-pentadiene (56 ° C.), 3-methyl-1,3-pentadiene (75 ° C.), 3-methyl-1,4-pentadiene (55 ° C), 4-methyl-1,3-pentadiene (75 ° C), cyclohexane (81 ° C), 2,3-dimethyl-1-butene (56 ° C), 2,3-dimethyl-2-butene (73) ° C), 3,3-dimethyl-1-butene (41 ° C), 2-ethyl-1-butene (64 ° C), 1-hexene (64 ° C), cis-2-hexene (68 ° C), trans-2 -Hexene (68 ° C), tra s-3-hexene (67 ° C), methylcyclopentane (71 ° C), 2-methyl-1-pentene (62 ° C), 2-methyl-2-pentene (67 ° C), 3-methyl-1-pentene ( 54 ° C), 3-methyl-2-pentene (69 ° C), 4-methyl-1-pentene (53 ° C), cis-4-methyl-2-pentene (57 ° C), 2,2-dimethylbutane (47 ° C), 2,3-dimethylbutane (58 ° C), hexane (68 ° C), 2-methylpentane (62 ° C), 3-methylpentane (64 ° C), cyclopentene (44 ° C), 3-methyl-1, Examples thereof include aliphatic hydrocarbon compounds or alicyclic hydrocarbon compounds having a boiling point of less than 130 ° C., such as 2-butadiene (40 ° C.), piperylene (42 ° C.), and cyclopentane (50 ° C.). Among these, as the aliphatic hydrocarbon compound solvent or the alicyclic hydrocarbon compound solvent, decahydronaphthalene represented by the following formula (1) and derivatives thereof are preferable. Decahydronaphthalene and its derivatives represented by the following formula (1) are compounds having a decahydronaphthalene skeleton, and examples thereof include decahydronaphthalene, methyldecahydronaphthalene, ethyldecahydronaphthalene, and dimethyldecahydronaphthalene.

R < ¹ > -R < ⁸ > in Formula (1) is a C1-C20 aliphatic hydrocarbon group which may be a hydrogen atom or may have a substituent. R ^{1 to} R ⁸ may be different from each other.

  In the raw material polypropylene solution preparation step, the raw material polypropylene is added to the aliphatic hydrocarbon compound solvent, the alicyclic hydrocarbon compound solvent, or a mixed solvent thereof, and a temperature equal to or higher than the melting point of the raw material polypropylene, preferably By heating at a temperature higher than the melting point of the raw material polypropylene by 10 ° C. or more, particularly preferably at a temperature higher than the melting point of the raw material polypropylene by 20 ° C. or more, more preferably at a temperature higher than the melting point of the raw material polypropylene by 30 ° C. Is dissolved in the solvent to obtain the raw material polypropylene solution. Specifically, when a raw material polypropylene having a melting point of 150 ° C. is used, heating is performed at a temperature of 150 ° C. or higher. And in this case, the raw material polypropylene solution can be made more uniform, and the heating temperature is preferably 160 ° C. or more, in particular, in that polypropylene particles having a small particle size and a narrow particle size distribution and good dispersibility can be obtained. Preferably it is 170 degreeC or more, More preferably, you may be 180 degreeC or more. The upper limit of the heating temperature is not particularly limited, but is usually 250 ° C. or less, preferably 200 ° C. or less, from the viewpoint of handleability.

  In the raw material polypropylene solution, the concentration of the raw material polypropylene is preferably 5 g / L or less, particularly preferably 0.05 to 5 g / L, and still more preferably 0.05 to 2.5 g / L. When the concentration of the raw material polypropylene is within the above range, polypropylene fine particles having a small particle size, a narrow particle size distribution and good dispersibility can be obtained.

  In order to uniformly dissolve the raw material polypropylene in the solvent, it is preferably heated for 30 minutes or more, particularly preferably 60 minutes or more, preferably 0.8 m / s or more, particularly preferably 1 under heating at the above temperature. Stir at a speed of 6 m / s or more. The upper limit of the stirring time is not particularly limited, but is 120 minutes or less from the viewpoint of economy.

  In the method for producing polypropylene fine particles of the present invention, the precipitation step is then performed. The precipitation step is a step of cooling the raw material polypropylene solution from a temperature equal to or higher than the melting point of the raw material polypropylene, that is, cooling from the heating temperature in the raw material polypropylene solution preparation step to precipitate the polypropylene fine particles. .

  When cooling the raw material polypropylene solution in the precipitation step, the raw material polypropylene solution is heated from the heating temperature in the raw material polypropylene solution preparation step to 0 ° C. or less, preferably from the heating temperature in the raw material polypropylene solution preparation step. Cooling from 0 ° C. to −40 ° C., particularly preferably from the heating temperature in the raw material polypropylene solution preparation step to −10 ° C. to −30 ° C., has a small particle size and a narrow particle size distribution. From the viewpoint of obtaining spherical polypropylene fine particles with good dispersibility. Further, it is preferable that the cooling rate when cooling the raw material polypropylene solution is high, and in particular, when cooling at a rate of 20 ° C./min to 100 ° C./min, spherical polypropylene fine particles having a small particle size and a narrow particle size distribution are obtained. Can be preferable. In cooling, the cooling method is not particularly limited, but it is preferable that the entire raw polypropylene solution is cooled uniformly. In particular, it is preferable to cool in a stationary state because the particle diameter is small and uniform spherical polypropylene fine particles can be obtained. In the precipitation step, by setting the cooling rate of the raw polypropylene solution and the cooling temperature of the raw polypropylene solution within the above ranges, spherical polypropylene fine particles having a small particle size, a narrow particle size distribution, and good dispersibility can be obtained. Can do.

  In the precipitation step, the shape of the cooling container when cooling the raw material polypropylene solution is preferably, for example, a cylindrical shape, and it is easier to obtain uniform fine particles when the distance from the cooling surface to the center of the solution is shorter. preferable. The method of cooling the raw material polypropylene solution is not particularly limited, and examples thereof include a method of cooling the cooling container with air in an atmosphere of 0 ° C. or lower, or cooling with a refrigerant.

  In the precipitation step, the raw polypropylene solution is cooled to a predetermined cooling temperature, and then allowed to stand in the state of being kept cool at the cooling temperature, preferably 10 minutes or more, particularly preferably 30 minutes or more. After the raw polypropylene solution is cooled, the slurry is allowed to stand at the cooling temperature for the above time, whereby a slurry solution of spherical polypropylene fine particles with few particle connections can be obtained in a high yield.

The polypropylene fine particles obtained in the precipitation step can be used as a slurry while being dispersed in the solvent. However, the polypropylene fine particles separated from the solvent by a technique such as filtration or centrifugation are volatilized such as ethanol. It is preferable to prepare a slurry solution by dispersing in a highly soluble solvent because the polypropylene fine particles can be easily dried. In addition, when the solvent in the raw material polypropylene solution is solidified by cooling, the solidified product is heated to a temperature not lower than the melting point of the solvent and not exceeding the softening point (110 ° C.) of the polypropylene, and then the polypropylene. The fine particles and the solvent are separated.
In addition, if necessary, the polypropylene fine particle slurry solution can be dried to obtain powdered polypropylene fine particles. The drying method is not particularly limited, and existing methods such as spray drying, vacuum drying, heat drying, airflow drying, and vibration fluidized drying can be used. In particular, the polypropylene fine particles separated from the solvent by a technique such as filtration or centrifugation are dispersed in a highly volatile solvent such as ethanol to form a slurry solution, and then the softening point (110 ° C.) of the polypropylene is reduced. Drying by spray drying at a temperature not exceeding to obtain the powdery polypropylene fine particles is preferable because spherical polypropylene fine particles having few connected particles can be obtained in a high yield.

  Thus, a polypropylene microparticle can be obtained by performing the manufacturing method of the polypropylene microparticle of this invention. The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention are isotactic polypropylene having a number average molecular weight of 10,000 or more and an isotactic pentad fraction of 95% or more, or a number average molecular weight of 10,000. It is composed of syndiotactic polypropylene having a syndiotactic pentad fraction of 95% or more, the maximum particle size is 50 μm or less, the particle size distribution index (SPAN) is 1.5 or less, and the average circularity is 0.00. Polypropylene fine particles having a spherical shape of 60 to 0.96 and fine irregularities on the surface.

The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention are spherical particles having a narrow particle size distribution, and there are many fine irregularities on the surface. FIG. 1 is an SEM photograph of polypropylene fine particles obtained by performing the method for producing polypropylene fine particles of the present invention. The polypropylene fine particles in FIG. 1 are spherical particles having a narrow particle size distribution, and a large number of irregularities exist on the surface.
On the other hand, FIG. 2 shows polypropylene particles obtained by performing the conventional physical melt dispersion method. The polypropylene particles in FIG. 2 are composed of substantially spherical particles having a wide particle size distribution, and the surface thereof is smooth. And irregularities are not observed. The physical melt dispersion method is a process in which a thermoplastic resin composition is mixed with a dispersion medium that is not compatible with the composition, heated to a temperature equal to or higher than the melting point of the resin composition, and dispersed into fine particles. And the manufacturing method of substantially spherical composite powder including the process of cooling the microparticles | fine-particles of this obtained resin composition to the temperature below the melting | fusing point, and making it into substantially spherical powder.

The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention are fine particles having a maximum particle size of 50 μm or less. In the present invention, the fact that the maximum particle size of the polypropylene fine particles is 50 μm or less is confirmed by the fact that particles having a particle size exceeding 50 μm are not measured in the particle size distribution of the polypropylene fine particles obtained by the laser light scattering diffraction method. The measurement conditions are as follows.
Using a laser light scattering diffraction particle size analyzer (MICROTRAC-HRA: manufactured by Nikkiso Co., Ltd.), the obtained polypropylene fine particle powder or slurry solution was used in an amount of the polypropylene fine particles in the range of 0.05 g to 0.20 g. Then, it is put into an ethanol solvent so that it falls within the optimum range indicated by the apparatus, and the particle size distribution of the volume statistic is obtained. Further, D90 (90% particle size (μm) in the cumulative particle size distribution in the cumulative particle size distribution), D50 (50% particle size (μm) in the cumulative particle size distribution), D10 (integral in the volume cumulative particle size distribution) The particle size is 10% (μm)), and the particle size distribution index (SPAN) is calculated by the following formula.
SPAN = (D90-D10) / D50
In addition, the preliminary dispersion treatment by adding a dispersing agent or ultrasonic shaking is not performed.

  The average particle diameter (D50) of the polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention is 1 μm to 40 μm, preferably 5 μm to 20 μm.

  The particle size distribution index (SPAN = (D90-D10) / D50) of the polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention is 1.5 or less, preferably 1.0 or less. The SPAN value indicates the degree of spread of the particle size distribution. The smaller the value, the narrower and sharper the particle size distribution and the more uniform the particle diameter.

  In the present invention, D10, D50, and D90 are particles corresponding to 10%, 50%, and 90%, respectively, of volume cumulative volume fractions in the volume cumulative particle size distribution of polypropylene fine particles obtained by a laser light scattering diffraction method. Indicates the diameter.

  The shape of the polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention is such that the maximum particle size is 50 μm or less and the particle size distribution index (SPAN) is 1.5 or less, like the polypropylene fine particles in FIG. The surface of the polypropylene fine particle has a large number of minute irregularities on the surface of the polypropylene fine particle having an average circularity of 0.60 to 0.96.

  The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention are spherical having an average circularity of 0.60 to 0.96, preferably 0.70 to 0.96. In the present invention, the circularity is defined as the ratio of the circumference of a circle having an area equal to the area of a particle obtained from the binarized image and the circumference obtained from the binarized image.

  The number average molecular weight (Mn) of the polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention is 10,000 or more, preferably 50,000 or more.

The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention have an isotactic pentad fraction of 95% or more, preferably 99% or more, or a syndiotactic pentad fraction of 95%. Above, preferably 99% or more of syndiotactic polypropylene. In the present invention, the isotactic pentad fraction or the syndiotactic pentad fraction is defined as follows. The isotactic pentad fraction or syndiotactic pentad fraction is the ratio of the methyl group in the isotactic structure or syndiotactic structure in the pentad unit in the methyl group of the polypropylene resin, and its value F (mmmm ) Or F (rrrr) is represented by the following formula:
F (mmmm) or F (rrrr) = (Immmm or Irrrr) / I (all methyl groups directly connected to the polymer main chain)
Is required. Here, Immmm or Irrrr represents the area of the peak attributed to mmmm pentad or rrrr pentad in the ¹³ C-NMR spectrum, and I (all methyl groups directly connected to the polymer main chain) is directly connected to the polymer main chain. The sum of the peak areas of signals derived from the methyl group is shown.

  The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention have an isotactic polypropylene having a number average molecular weight (Mn) of 10,000 or more and an isotactic pentad fraction of 99% or more, or a number average molecular weight of 1. It is a syndiotactic polypropylene having a syndiotactic pentad fraction of 99% or more, and having an average particle diameter (D50) of 40 μm or less, in that the mechanical strength and heat resistance of the particles are excellent. preferable.

  Furthermore, the polypropylene fine particles obtained by performing the method for producing polypropylene fine particles of the present invention are isotactic polypropylene having a number average molecular weight (Mn) of 10,000 or more and an isotactic pentad fraction of 99% or more, or a number average molecular weight. Is a syndiotactic polypropylene having a syndiotactic pentad fraction of 99% or more and an average particle size (D50) of 20 μm or less without impairing the mechanical strength and heat resistance of the polypropylene. It is particularly preferable in that it can be highly dispersed.

  The polypropylene fine particles obtained by carrying out the method for producing polypropylene fine particles of the present invention include antioxidants, ultraviolet absorbers, lubricants, antistatic agents, flame retardants, fillers, metal deactivators, pigments, dyes, crystal nucleating agents, and the like. These additives can be contained as required.

  According to the method for producing polypropylene fine particles of the present invention, the particle size of the polypropylene fine particles can be made smaller and the particle size distribution can be made narrower than the conventional production method. Moreover, in the method for producing polypropylene fine particles of the present invention, spherical polypropylene fine particles can be obtained. Moreover, the method for producing polypropylene fine particles of the present invention is simpler than the conventional production method.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

Evaluation was performed by the following method.
(Measurement of molecular weight and molecular weight distribution)
The molecular weight and molecular weight distribution of the polypropylene fine particles were determined by gel permeation chromatography (GPC) (manufactured by GPCV2000 Waters). A column of UT-806M (manufactured by Shodex) × 3 was used as a column, o-dichlorobenzene was used as a solvent, a 1 mg / 1 mL concentration sample was introduced, and measurement was performed at 140 ° C. A calibration curve was prepared using standard polystyrene manufactured by Shodex.

(Measurement of melting point)
The temperature at the position of the maximum peak in the endothermic curve of differential scanning calorimetry (DSC) was defined as the melting point (Tm) of the polypropylene fine particles. In the measurement, the sample is packed in an aluminum pan, heated to 200 ° C. at 10 ° C./minute, held at 200 ° C. for 5 minutes, cooled to room temperature at 20 ° C./minute, and then heated at 10 ° C./minute. The endothermic curve was determined.

(Measurement of boiling n-heptane insoluble fraction (HI))
The ratio (HI) of boiling n-heptane insoluble matter in the polypropylene fine particles was defined as the proportion (mass%) of n-heptane insoluble when the polypropylene fine particles were extracted with boiling n-heptane for 6 hours.

(Content of polypropylene having a melting point of less than 130 ° C. and low stereoregularity)
A round bottom flask equipped with a stirrer is charged with 2.0 g of polypropylene and 200 mL of decahydronaphthalene and stirred at 180 ° C. for 60 minutes to prepare a uniform solution. The flask is then immediately immersed in a 23 ° C. water bath and the solution is cooled to 23 ° C. After cooling, the precipitate is collected by filtration, dried, and the mass X (g) of the precipitate is measured. From the mass X (g) of the precipitate, the content Y (mass%) of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity was determined by the following formula.
Y (mass%) = {(2.0−X) /2.0} × 100

(Measurement of isotactic pentad fraction)
The isotactic pentad fraction is determined as follows: Isotactic linkage of pentad units in a polypropylene molecular chain as measured by the method described by Zambelli et al., Macromolecules, 6, 925 (1973) (in other words, 5 propylene monomer units were meso-bonded in succession) Is the fraction of propylene monomer units in the center of the chain) and is calculated using ¹³ C-NMR. Specifically, the area fraction of the mmmm peak relative to the total absorption peak in the methyl carbon region of the ¹³ C-NMR spectrum was determined as the isotactic pentad fraction. For the ¹³ C-NMR measurement, JNM-ECA400 manufactured by JEOL Ltd. was used.
< ^13C -NMR measurement conditions>
Measurement mode: Proton decoupling method
Pulse width: 7.25 μsec
Pulse repetition time: 7.4 sec
Integration count: 10,000 times
Solvent: Tetrachloroethane-d2
Sample concentration: 200 mg / 3.0 ml

(Measurement method of particle size and particle size distribution)
Using a laser light scattering diffraction particle size analyzer (MICROTRAC-HRA: manufactured by Nikkiso Co., Ltd.), the obtained polypropylene fine particle slurry solution was placed in an apparatus with an amount of the polypropylene fine particles in the range of 0.05 g to 0.20 g. Was placed in an ethanol solvent so as to be included in the optimum range indicated by, and the particle size distribution of volume statistics was determined. D90 (90% particle size (μm) in the cumulative particle size distribution), D50 (50% particle size (μm) in the cumulative particle size distribution), D10 (integrated in the volume cumulative particle size distribution) A particle size of 10% in terms of particle size (μm)) was determined, and a particle size distribution index (SPAN) was calculated by the following formula.
SPAN = (D90-D10) / D50
Moreover, the volume ratio of the particle | grains exceeding 50 micrometers was set to V50. The preliminary dispersion treatment by adding a dispersing agent, ultrasonic shaking, or the like was not performed.

(Measuring method of average circularity)
A particle image photographed by a scanning electron microscope (SEM) (JSM-7500F; manufactured by JEOL Ltd., magnification: 5000 times) was taken into an image analyzer (Macview; manufactured by Mountech) and measured as follows. did. The projected area (A) and the perimeter (PM) of the particles are measured from the photograph. The circularity of the particles was determined by calculating the circumference (C) of a circle having an area equal to the projected area (A) and calculating the ratio (C / PM). With such a method, the circularity of 1000 arbitrary particles was obtained, and the average value thereof was defined as the average circularity.

(Synthesis of raw material polypropylene 1)
<Synthesis of isotactic polypropylene 1>
Triethylaluminum and cyclohexylmethyl using a solid catalyst having a high isospecificity prepared from an alkoxy-containing magnesium compound, a titanium halide compound and an electron-donating compound, as disclosed in JP-A-63-3010 Dimethoxysilane was added, liquefied propylene (1.4 L) and 1.5 L of hydrogen gas were charged, and polymerization was carried out at 70 ° C. for 1 hour. The number average molecular weight and molecular weight distribution of the obtained polymer, the melting point, and the ratio (HI) of the boiling insoluble n-heptane in the resulting polymer were Mn = 7.2 × 10 ⁴ and Mw / Mn = 5.24, respectively. Tm = 158.3 ° C. and HI = 98.5 wt%.

<Purification of isotactic polypropylene 1>
A 500 mL round bottom flask equipped with a stirrer was charged with 2.0 g of the polymer obtained in Synthesis 1 of isotactic polypropylene and 200 mL of decahydronaphthalene, and stirred at 180 ° C. for 60 minutes to obtain a uniform solution. Was prepared. The flask was then immediately immersed in a 23 ° C. water bath and the solution was cooled to 23 ° C. After cooling, the precipitate was collected by filtration and dried to obtain raw material polypropylene a. The weight of the obtained raw material polypropylene a was 1.8 g. The content of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity in the obtained raw material polypropylene a was 0.1% by mass.

Example 1
A 500 mL round bottom flask equipped with a stirrer was charged with 0.5 g of the raw material polypropylene a and 200 mL of decahydronaphthalene (boiling point: 185 to 195 ° C.) and stirred at 180 ° C. for 60 minutes. Was dissolved to prepare a uniform 180 ° C. solution. Next, this solution was immediately transferred to a 500 mL cylindrical container cooled to −20 ° C., and cooled to −20 ° C. at a cooling rate of 25 ° C./min. Thereafter, the contents of the cylindrical container were allowed to stand at −20 ° C. for 60 minutes. Thereafter, the temperature of the contents of the cylindrical container is returned to room temperature, the precipitate is precipitated by centrifugation, and after removing the solvent as a supernatant, the slurry is dispersed in ethanol so that the slurry concentration becomes 5 mg / ml. It was. Thereafter, the precipitate was dried by a spray drying apparatus (Pulvis GB22: manufactured by Yamato Chemical Co., Ltd.) to obtain polypropylene fine particles a.
The drying conditions are as follows.
Drying temperature (outlet temperature): 90 ° C
Dry air flow rate: 0.4 m ³ / min
Slurry input amount: 30 ml / min
Solvent: Ethanol Slurry concentration: 5 mg / ml
The particle size distribution of the obtained polypropylene fine particles a obtained by a laser light scattering diffraction method was D50 = 12.4 μm, D10 = 8.9 μm, D90 = 18.0 μm, and SPAN = 0.73. V50 was 0%.
Further, the obtained polypropylene fine particles a were magnified 2000 times with a scanning electron microscope (SEM) (JSM-7500F: manufactured by JEOL Ltd.), and the particle shape was observed. Was observed to have a large number of minute irregularities (FIG. 1). The average circularity was 0.73.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles a was 7.1 × 10 ⁴ , and the isotactic pentad fraction was 99.7 mol%.

(Example 2)
The same operation as in Example 1 was performed except that the raw material polypropylene a was changed to 0.5 g instead of the raw material polypropylene a to obtain polypropylene fine particles b.
The particle size distribution of the obtained polypropylene fine particles b was D50 = 5.8 μm, D10 = 4.2 μm, D90 = 8.5 μm, and SPAN = 0.74. V50 was 0%.
Furthermore, when the obtained polypropylene fine particles b were magnified 2000 times with a scanning electron microscope (SEM) and the particle shape was observed, it was observed that the surface of the spherical particles had many minute irregularities. It was done. The average circularity was 0.75.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles b was 7.1 × 10 ⁴ , and the isotactic pentad fraction was 99.7 mol%.

Example 3
The same operation as in Example 1 was performed except that the raw material polypropylene a1.0 g was used instead of the raw material polypropylene a0.5 g to obtain polypropylene fine particles c.
The particle size distribution of the obtained polypropylene fine particles c was D50 = 12.2 μm, D10 = 8.4 μm, D90 = 18.0 μm, and SPAN = 0.79. V50 was 0%.
Further, the obtained polypropylene fine particles c were magnified 2000 times with a scanning electron microscope (SEM), and the particle shape was observed. As a result, it was observed that there were many minute irregularities on the surface of the spherical particles. It was done. The average circularity was 0.71.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles c was 7.1 × 10 ⁴ , and the isotactic pentad fraction was 99.7 mol%.

Example 4
The same operation as in Example 1 was carried out except that 200 mL of n-butylcyclohexane (boiling point; 180 ° C.) was used instead of 200 mL of decahydronaphthalene and that the solution was dissolved at 170 ° C. instead of being dissolved at 180 ° C. Polypropylene fine particles d were obtained.
The particle size distribution of the obtained polypropylene fine particles d was D50 = 15.7 μm, D10 = 9.0 μm, D90 = 25.5 μm, and SPAN = 1.05. V50 was 0%.
Furthermore, when the obtained polypropylene fine particles d were magnified 2000 times with a scanning electron microscope (SEM) and the shape of the particles was observed, it was observed that there were many minute irregularities on the surface of the spherical particles. It was done. The average circularity was 0.72.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles d was 7.1 × 10 ⁴ , and the isotactic pentad fraction was 99.7 mol%.

  From Examples 1 to 4, it was found that the use of decahydronaphthalene as a solvent increases the effect of narrowing the particle size distribution of the polypropylene fine particles.

(Example 5)
The same operation as in Example 1 was carried out except that 200 mL of n-decane (boiling point: 174.2 ° C.) was used instead of 200 mL of decahydronaphthalene, and dissolution was performed at 170 ° C. instead of dissolution at 180 ° C. And polypropylene fine particles e were obtained.
The particle size distribution of the obtained polypropylene fine particles e was D50 = 12.6 μm, D10 = 6.1 μm, D90 = 22.5 μm, and SPAN = 1.30. V50 was 0%.
Further, the obtained polypropylene fine particles e were magnified 2000 times with a scanning electron microscope (SEM), and the particle shape was observed. As a result, it was observed that there were many minute irregularities on the surface of the spherical particles. It was done. The average circularity was 0.70.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles e was 7.1 × 10 ⁴ , and the isotactic pentad fraction was 99.7 mol%.

(Synthesis of raw material polypropylene 2)
<Synthesis of isotactic polypropylene 2>
The same operation as in Synthesis 1 of isotactic polypropylene was performed except that the polymerization was performed by increasing the amount of hydrogen gas to 9 L. The molecular weight and molecular weight distribution of the product polymer, the melting point, and the ratio of boiling n-heptane insoluble matter (HI) in the product polymer were Mn = 4.0 × 10 ⁴ , Mw / Mn = 5.29, Tm = It was 159.4 ° C. and HI = 96.6 wt%.

<Purification of isotactic polypropylene 2>
Using 2.0 g of the polymer obtained in Synthesis 2 of Isotactic Polypropylene, the same operation as in Purification 1 of Isotactic Polypropylene was performed to obtain a raw material polypropylene b. The weight of the obtained raw material polypropylene b was 1.9 g. The content of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity in the obtained raw material polypropylene b was 0.1% by mass.

(Example 6)
The same operation as in Example 1 was carried out except that the raw material polypropylene b was changed to 0.5 g instead of the raw material polypropylene a 0.5 g to obtain polypropylene fine particles f.
The particle size distribution of the obtained polypropylene fine particles f obtained by a laser light scattering diffraction method was D50 = 9.7 μm, D10 = 7.2 μm, D90 = 13.4 μm, and SPAN = 0.64. V50 was 0%.
Furthermore, when the obtained polypropylene fine particles f were magnified 2000 times with a scanning electron microscope (SEM) and the particle shape was observed, it was observed that there were many minute irregularities on the surface of the spherical particles. It was done. The average circularity was 0.73.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particle f was 3.9 × 10 ⁴ , and the isotactic pentad fraction was 99.7 mol%.

(Synthesis of raw material polypropylene 3)
<Synthesis of isotactic polypropylene 3>
Methylaluminoxane was added to dimethylsilylbis (tetrahydroindenyl) zirconium dichloride as disclosed in JP-A-5-43624 and the like, and solution polymerization was performed at 0 ° C. under normal pressure of propylene to obtain a raw material polypropylene c. The obtained raw material polypropylene c had a molecular weight, a molecular weight distribution, and a melting point of Mn = 67.4 × 10 ⁴ , Mw / Mn = 1.91, and Tm = 159.2 ° C., respectively. The content of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity in the obtained raw material polypropylene c was 0% by mass. In general, polypropylene obtained with a metallocene catalyst is a homogeneous polymer and thus was not purified.

(Example 7)
The same operation as in Example 1 was carried out except that 0.5 g of the raw material polypropylene c was used instead of the raw material polypropylene a 0.5 g, thereby obtaining polypropylene fine particles g.
The particle size distribution of the obtained polypropylene fine particles g was D50 = 13.5 μm, D10 = 9.7 μm, D90 = 19.6 μm, and SPAN = 0.64. V50 was 0%.
Further, the obtained polypropylene fine particles g were magnified 2000 times with a scanning electron microscope (SEM), and the particle shape was observed. As a result, it was observed that many fine irregularities existed on the surface of the spherical particles. It was done. The average circularity was 0.75.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles g was 67.4 × 10 ⁴ , and the isotactic pentad fraction was 99.0 mol%.

(Synthesis of raw material polypropylene 4)
<Synthesis 1 of isotactic (propylene-1-hexene) copolymer>
Propylene and 1-hexene were copolymerized using the highly isospecific solid catalyst used in Synthesis 1 of isotactic polypropylene to obtain an isotactic (propylene-1-hexene) copolymer. The molecular weight and molecular weight distribution of the resulting copolymer, the melting point, and the 1-hexene content in the resulting copolymer were Mn = 3.8 × 10 ⁴ , Mw / Mn = 3.31, and Tm = 149. The content of 1-hexene at 7 ° C. was 0.78 mol%.
Incidentally, Makromol 1-hexene content: product ^copolymer, the spectrum obtained using 13 C-NMR by Uozumi et al. Chem. , 193, 823 (1992). Specifically, 1-hexene content was determined by the following formula using the area values of three types of peaks derived from methylene carbon in the main chain observed at 40 to 50 ppm.
1-hexene content = 1/2 [HP] + [HH]
[HP] = I (HP) / {I (HH) + I (HP) + I (PP)}
[HH] = I (HH) / {I (HH) + I (HP) + I (PP)}
Here, I (HH), I (HP) and I (PP) are (1-hexene)-(1-hexene) linkage, (1-hexene)-(propylene) linkage, (propylene)-(propylene), respectively. ) Shows the area value of the methylene carbon peak attributed to the chain.

<Purification 1 of isotactic (propylene-1-hexene) copolymer>
The same operation as in Purification 1 of isotactic polypropylene was performed to obtain raw material polypropylene d. The weight of the obtained raw material polypropylene d was 1.92 g.
The content of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity in the obtained raw material polypropylene d was 0% by mass.

(Example 8)
The same operation as in Example 1 was performed except that the raw material polypropylene d was changed to 0.5 g instead of the raw material polypropylene a 0.5 g to obtain polypropylene fine particles h.
The particle size distribution of the obtained polypropylene fine particles h was unimodal, with D50 = 11.9 μm, D10 = 8.6 μm, D90 = 17.5 μm, and SPAN = 0.75. V50 was 0%.
Further, the obtained polypropylene fine particles h were magnified 2000 times with a scanning electron microscope (SEM), and the particle shape was observed. As a result, it was observed that many fine irregularities existed on the surface of the spherical particles. It was done. The average circularity was 0.80.
The number average molecular weight (Mn) of the isotactic (propylene-1-hexene) copolymer constituting the obtained polypropylene fine particles h is 3.8 × 10 ⁴ , and the isotactic pentad fraction is 95. It was 5 mol%.

(Synthesis of raw material polypropylene 5)
<Synthesis 1 of hydroxyl group-containing isotactic polypropylene>
By Sugawara et al. Polym. Sci. : Part A: Polym. CHem. , 42, 52 (2004), methylaluminoxane is added to dimethylsilylbis (tetrahydroindenyl) zirconium dichloride, and diisobutyl (5-hexene-1-oxyl) at 0 ° C. under normal pressure of propylene. ) Copolymerization with aluminum was performed to synthesize hydroxyl-containing isotactic polypropylene (raw material polypropylene e). The number average molecular weight and molecular weight distribution, melting point, and hydroxyl group content in the resulting copolymer of the obtained raw material polypropylene e were Mn = 15.6 × 10 ⁴ , Mw / Mn = 2.79, Tm = 140.4, respectively. The temperature was 1.5 wt%. The content of the polypropylene having a melting point of less than 130 ° C. and low stereoregularity in the obtained raw material polypropylene e was 0% by mass. In general, polypropylene obtained with a metallocene catalyst is a homogeneous polymer and thus was not purified.
In addition, since the hydroxyl group content in the raw material polypropylene e is equal to the 5-hexen-1-ol content in the polymer, the 5-hexen-1-ol content can be obtained using ¹³ C-NMR. Calculated from the spectrum.
Specifically, using the area values of three types of peaks derived from methylene carbon in the main chain observed at 40 to 50 PPm, the hydroxyl group content was determined by the following formula.
5-hexen-1-ol content = 1/2 [HP] + [HH]
[HP] = I (HP) / {I (HH) + I (HP) + I (PP)}
[HH] = I (HH) / {I (HH) + I (HP) + I (PP)}
Here, I (HH), I (HP) and I (PP) are (5-hexen-1-ol)-(5-hexen-1-ol) linkage and (5-hexen-1-ol), respectively. -The area value of the methylene carbon peak attributed to a-(propylene) chain and a (propylene)-(propylene) chain is shown.

Example 9
The same operation as in Example 1 was carried out except that 0.5 g of the raw material polypropylene a was used instead of the raw material polypropylene a to obtain polypropylene fine particles i.
The particle size distribution of the obtained polypropylene fine particles i was unimodal, with D50 = 5.7 μm, D10 = 3.1 μm, D90 = 11.5 μm, and SPAN = 0.65. V50 was 0%.
Furthermore, when the obtained polypropylene fine particles i were magnified 2000 times with a scanning electron microscope (SEM) and the shape of the particles was observed, it was observed that there were many fine irregularities on the surface of the spherical particles. It was done. The average circularity was 0.83.
The number average molecular weight (Mn) of the isotactic polypropylene constituting the obtained polypropylene fine particles i was 15.6 × 10 ⁴ , and the isotactic pentad fraction was 90.5 mol%.

(Comparative Example 1)
A 500 mL round bottom flask equipped with a stirrer was charged with 0.5 g of the raw material polypropylene a and 200 mL of p-xylene (boiling point: 138 ° C.), and stirred at 138 ° C. for 60 minutes to prepare a uniform solution. . Next, this solution was immediately transferred to a 500 mL cylindrical container cooled to 10 ° C., and cooled to 10 ° C. at a cooling rate of 25 ° C./min. Thereafter, the contents of the cylindrical container were allowed to stand at 10 ° C. for 60 minutes. Thereafter, with the cylindrical container standing still, the temperature of the contents of the cylindrical container was returned to room temperature, the precipitate was precipitated by a centrifuge, the solvent was removed as a supernatant, and replaced with ethanol. Thereafter, the precipitate was dried by the same method as in Example 1 to obtain polypropylene fine particles j.
The particle size distribution of the obtained polypropylene fine particles j was D50 = 18.5 μm, D10 = 8.9 μm, D90 = 33.6 μm, and SPAN = 1.34. V50 was 0.9%.
Furthermore, when the obtained polypropylene fine particles j were magnified 2000 times with a scanning electron microscope (SEM) and the particle shape was observed, they were indefinite and spherical particles were not observed.

(Comparative example 2) <Method according to paragraph number 0187 of JP-A-2002-145947>
0.5 g of the raw material polypropylene e and 175 g of toluene (boiling point: 110.6 ° C.) are placed in a 500 mL round bottom flask equipped with a stirrer and heated to 110 ° C. to completely dissolve, then up to 85 ° C. The temperature was lowered from 85 ° C. to 40 ° C. for 4.5 hours and from 40 ° C. to 30 ° C. in 30 minutes to obtain a dispersion. The average particle diameter of the obtained dispersion was 600 μm or more.

(Comparative Example 3)
The particle size distribution of the 45 μm product manufactured by Trial Co. was D50 = 48.2 μm, D10 = 33.3 μm, D90 = 72.8 μm, and SPAN = 0.82. V50 was 50.6%. The number average molecular weight (Mn) of the isotactic polypropylene constituting the 45 μm product made by Trial is 3.1 × 10 ⁴ , and the isotactic pentad fraction has many miscellaneous peaks. I could not.
Furthermore, when a 45 μm product manufactured by Trial Co. was magnified 500 times with a scanning electron microscope (SEM) and the particle shape was observed, it was spherical and the surface of the particles was smooth (FIG. 2). The average circularity was 0.77.
The 45 μm product manufactured by Trial is polypropylene fine particles manufactured by a physical melt dispersion method.
(Comparative Example 4)
A 500 mL round bottom flask equipped with a stirrer was charged with 0.5 g of the raw material polypropylene a and 200 mL of n-butylbenzene (boiling point: 183 ° C.) and stirred at 180 ° C. for 60 minutes. Dissolved to prepare a uniform 180 ° C. solution. Next, this solution was immediately transferred to a 500 mL cylindrical container cooled to −20 ° C., and cooled to −20 ° C. at a cooling rate of 25 ° C./min. Thereafter, the contents of the cylindrical container were allowed to stand at −20 ° C. for 60 minutes. Thereafter, with the cylindrical container standing still, the temperature of the contents of the cylindrical container was returned to room temperature, the precipitate was precipitated by a centrifuge, the solvent was removed as a supernatant, and replaced with ethanol. Thereafter, the precipitate was dried by the same method as in Example 1 to obtain polypropylene fine particles k.
The particle size distribution of the obtained polypropylene fine particles k was D50 = 24.5 μm, D10 = 12.8 μm, D90 = 41.4 μm, and SPAN = 1.17. V50 was 5.2%.
Furthermore, when the obtained polypropylene fine particles k were magnified 2000 times with a scanning electron microscope (SEM) and the particle shape was observed, the particles were indefinite and spherical particles were not observed.
(Comparative Example 5)
A 500 mL round bottom flask equipped with a stirrer was charged with 0.5 g of the raw material polypropylene a and 200 mL of decahydronaphthalene (boiling point: 185 to 195 ° C.) and stirred at 140 ° C. for 60 minutes. Was dissolved to prepare a uniform solution at 140 ° C. Next, this solution was immediately transferred to a 500 mL cylindrical container cooled to −20 ° C., and cooled to −20 ° C. at a cooling rate of 25 ° C./min. Thereafter, the contents of the cylindrical container were allowed to stand at −20 ° C. for 60 minutes. Thereafter, with the cylindrical container standing still, the temperature of the contents of the cylindrical container was returned to room temperature, the precipitate was precipitated by a centrifuge, the solvent was removed as a supernatant, and replaced with ethanol. Thereafter, the precipitate was dried by the same method as in Example 1 to obtain polypropylene fine particles l.
The particle size distribution of the obtained polypropylene fine particles 1 was D50 = 18.1 μm, D10 = 10.7 μm, D90 = 29.2 μm, and SPAN = 1.02. V50 was 1.2%.
Furthermore, when the obtained polypropylene fine particles 1 were magnified 2000 times with a scanning electron microscope (SEM) and the particle shape was observed, spherical particles were observed, but some irregular particles were also observed. It was.

  The polypropylene fine particles obtained by the present invention are used for various cosmetics such as a scrub facial cleanser, a carrier such as a catalyst, additives for printing ink and paint, a raw material for a porous body, a raw material for modeling, and the like.

Claims (8)

The raw material polypropylene is added to the aliphatic hydrocarbon compound solvent, the alicyclic hydrocarbon compound solvent, or a mixed solvent thereof, and dissolved by heating at a temperature 10 ° C. higher than the melting point of the raw material polypropylene to obtain a raw material polypropylene solution. A method for producing polypropylene fine particles, comprising: a raw material polypropylene solution preparation step; and a precipitation step in which the raw material polypropylene solution is cooled to a temperature range of 0 ° C. or less to precipitate polypropylene fine particles.   2. The method for producing polypropylene fine particles according to claim 1, wherein in the raw material polypropylene solution preparation step, the solvent for dissolving the raw material polypropylene is an alicyclic hydrocarbon compound having a boiling point of 160 ° C. or higher. The method for producing polypropylene fine particles according to claim 2, wherein the alicyclic hydrocarbon compound having a boiling point of 160 ° C or higher is decahydronaphthalene represented by the following formula (1) and a derivative thereof.

(In formula (1), R ^{1 to} R ⁸ represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 20 carbon atoms. R ^{1 to} R ⁸ may be different from each other.)   The method for producing polypropylene fine particles according to any one of claims 1 to 3, wherein the concentration of the raw material polypropylene in the raw material polypropylene solution is 5 g / L or less.   5. The method for producing polypropylene fine particles according to claim 1, wherein, in the precipitation step, the raw material polypropylene solution is cooled at a cooling rate of 20 ° C./min or more.   The method for producing polypropylene fine particles according to any one of claims 1 to 5, wherein the raw material polypropylene is isotactic polypropylene. Mass of precipitates obtained by stirring 2.0 g of the raw material polypropylene and 200 mL of decahydronaphthalene for 60 minutes at 180 ° C. to make a uniform solution, cooling the solution to 23 ° C., filtering and drying. From (g), the following formula (2):
Y (mass%) = {(2.0−X) /2.0} × 100 (2)
The content Y (mass%) of the low melting point and low stereoregularity polypropylene in the raw material polypropylene determined by the formula (1) is 1% by mass or less. A method for producing the polypropylene fine particles according to Item.   The method for producing polypropylene fine particles according to any one of claims 1 to 5, further comprising a purification step of removing polypropylene having a melting point of less than 130 ° C and low stereoregularity in the raw material polypropylene.