JPH0645702B2 - Method for producing thermoplastic resin fine particles - Google Patents

Description

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

In the present specification, "part" and "%" mean "part by weight" and "% by weight", respectively.

Prior art and its problems Thermoplastic resin is melted and dispersed in a specific silicone oil-based heat medium with stirring, cooled, precipitated as fine particles, and then separated from the medium. Such a method is known as a heat medium fusion precipitation method (for example, JP-A-63-108030, JP-A-63-108031, and JP-A-63-10803).
No. 2, etc.). However, in the conventional heat medium melt precipitation method, (a) the molten thermoplastic resin adheres to the wall of the reaction vessel and is not sufficiently dispersed, (b) the particle size distribution of the obtained fine particles is wide, (C) There are some problems to be solved such as lack of sphericity in particle shape.

Means for Solving the Problems In view of the problems of the known heat medium fusion precipitation method as described above, the present inventor has carried out various studies especially on the heat medium, and the properties required for the heat medium are We have found that it can be summarized as follows.

(A) It is thermally stable near the melting temperature (about 200 ° C.) of the thermoplastic resin.

(B) Warmness is not too sensitive (that is, no significant decrease in viscosity is observed under heating conditions).

(C) It is chemically stable and does not chemically react with the thermoplastic resin.

(D) The stirring power is easily transmitted to the thermoplastic resin having an appropriate viscosity and dispersed / melted in the heat medium.

(E) Melting the thermoplastic resin at a temperature as low as possible.

(F) It has an interfacial energy that favorably disperses the thermoplastic resin.

The present inventor has further researched on the basis of such knowledge, and as a result, a high-viscosity silicone oil containing fluorine oil has
It has been found that the heat medium can satisfy the above requirements.

It was also found that when a high-viscosity silicone oil containing the above-mentioned fluorine oil is further mixed with an organic solvent, further excellent results can be obtained.

That is, the present invention provides the following method for producing thermoplastic resin fine particles: a thermoplastic resin is melted and dispersed in a heating medium under stirring, then cooled and precipitated as fine particles, and then the medium. In the method for producing thermoplastic resin fine particles to be separated, fluorine oil is blended, and the viscosity at 25 ° C. is 5,000 to 10,000.
A method for producing fine thermoplastic resin particles, which comprises using 0 centistokes high-viscosity silicone oil as a heat medium.

The method for producing thermoplastic resin fine particles according to the above item, wherein the heat medium further contains at least one kind of organic solvent.

The thermoplastic resin used in the method of the present invention is not particularly limited, and examples thereof include polyamide, polyethylene, polypropylene, acrylic resin, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene sulfide. In the following, unless otherwise necessary, a thermoplastic resin is represented by a polyamide resin,
It goes without saying that the present invention is not limited to this.

As the polyamide resin, polyamide-6, -66,
-610, -11, -12, these mixed resin, etc. are illustrated.

In the present invention, fluorine oil that mainly functions as a dispersant for a thermoplastic resin is blended, and a high-viscosity silicone oil having a viscosity at 25 ° C. of 5,000 to 100,000 centistokes is used as a heat medium (hereinafter simply referred to as Sometimes called viscosity silicone oil).

As the fluorine oil, one having fluidity at room temperature is used, and more specifically, fluorine oil or fluorine grease having a structure represented by the following formula is exemplified.

The poly (trifluoroethylene chloride) represented by the above formula (1) usually has an average molecular weight of about 500 to 1300.
More preferably, it is about 00 to 1300. In this case, a high molecular weight grease-like substance (molecular weight 1100 to
(About 1300) and a low molecular weight substance having a fluidity at room temperature (a molecular weight of about 500 to 1000) may be mixed and used as a mixture having a fluidity at room temperature. Such a mixture is commercially available under the trade name "Daiflon" (manufactured by Daikin Industries, Ltd.).

The average molecular weight of the perfluoropolyether oil represented by the above formula (2) is usually about 2700 to 8400, and more preferably about 4500 to 8400. Also in this case, a high molecular weight compound and a low molecular weight compound having fluidity at room temperature may be mixed and used as a mixture having appropriate fluidity at room temperature. Some perfluoropolyether oils are commercially available under the trade name "Demnum" (manufactured by Daikin Industries, Ltd.). These fluorine oils are themselves chemically and thermally stable, and even at the melting temperature of the thermoplastic resin, the viscosity does not decrease so much and the dispersibility of the thermoplastic resin particles is increased to improve the shape of the generated particles. Demonstrate the effect of making spherical.

The heat medium substrate has a viscosity of usually 500 at 25 ° C.
A high-viscosity silicone oil of about 0 to 100,000 centistokes, more preferably about 20,000 to 50,000 centistokes is used. Specific examples of such silicone oil include those represented by the following general formula.

(A) Dimethyl polysiloxane: (N = 0 to about 2000) (b) Methylphenyl polysiloxane: (C) Alkyl-modified silicone: (R is an alkyl group having 1 to 10 carbon atoms or an aralkyl group) (d) Amino-modified silicone: (R is an alkyl group having 1 to 10 carbon atoms or an aralkyl group) (e) Alcohol-modified silicone: Or (R and R'are alkyl groups or aralkyl groups having 1 to 10 carbon atoms) (f) Fluorine-modified silicone: (G) Alkyl aralkyl polyether modified silicone: (POA means polyoxyalkylene) (h) Polyether-modified silicone: (POA means polyoxyalkylene) Incidentally, in the general formulas represented by the above (a) to (h), x + y is about 10,000 to 100,000, and x
And y are arbitrary integers that satisfy the above relationship.

Such a high-viscosity silicone oil increases the viscosity of the entire heating medium and improves the efficiency of stirring power for dispersing the thermoplastic resin. Further, since these high-viscosity silicone oils are stable both thermally and chemically, they can be used repeatedly. It goes without saying that these silicone oils may be used as a mixture of two or more kinds. Even a low-viscosity silicone oil that does not reach the above viscosity by itself can be used by mixing it with a high-viscosity silicone oil and adjusting the viscosity of the mixture within the above range.

The blending ratio of the fluorine oil to the high-viscosity silicone oil is about 0.2 to 50 parts, more preferably about 0.5 to 20 parts, with respect to the former 100 parts. If the blending ratio of the fluorine oil is too small, the dispersibility of the polyamide fine particles in the heat medium will not be sufficiently improved. On the other hand, if the amount is too large, the specific gravity of the fluoro oil (1.85-1.98)
Is higher than that of polyamide, so that the polyamide is lifted during melt heating and mixing, and sufficient stirring becomes difficult.

In the present invention, by adding at least one kind of organic solvent to the heating medium, the melting temperature is lowered by imparting an appropriate swelling property to a high-melting point thermoplastic resin such as a polyamide resin, in particular, according to the method of the present invention. The operability at the time of implementation can be improved. When targeting a resin having a low melting point, the compounding of an organic solvent is not particularly necessary. Such a decrease in the melting temperature also brings about an effect of suppressing deterioration of the heat medium itself. The organic solvent has fluidity at room temperature and preferably has a boiling point of 180 ° C. or higher,
It is more desirable that the boiling point is 200 ° C. or higher. Examples of such an organic solvent include the following.

Aliphatic hydrocarbons: tridecane, tetradecane, etc .; Aromatic hydrocarbons: triethyldiphenyl, etc .; Hydrogenated aromatic hydrocarbons: hydrogenated triphenyl, hydrogenated diphenyl, etc .; Alcohols: benzyl alcohol, glycerin, propylene glycol, etc. Esters; acetic acid ethylene glycol-mono-n-butyl ether and the like; in the above organic solvents, aliphatic hydrocarbons and aromatic hydrocarbons are commercially available as a mixed solvent having an initial boiling point and a dry point, Initial boiling point of 180 ° C or higher, more preferably 20
Those having a temperature of 0 ° C. or higher can be selected and used. For example, examples of the aliphatic hydrocarbon-based mixed solvent include those sold under the trade name "Thiozole" (manufactured by Chuo Kasei Co., Ltd.), and examples of the aromatic hydrocarbon-based mixed solvent include:
Trade name "Swazol # 1800" (Maruzen Petrochemical Co., Ltd.)
The products sold as "Made in Japan" are exemplified. The compounding amount of the organic solvent is usually 5 with respect to 100 parts of high-viscosity silicone oil
Approximately 20 parts, and the viscosity of the entire heating medium is 1 at 25 ° C.
It should be about 0000 to 100000 cps. The amount of organic solvent blended is 100 parts of high-viscosity silicone oil,
5 to 10 parts, and the viscosity of the entire heat medium is 2000
It is more preferable to set it to about 0 to 50,000 cps.

The method of the present invention is usually carried out as follows. Pelletized thermoplastic resin is added to a heat medium made of high-viscosity silicon oil mixed with fluorine oil or a heat medium mixed with an organic solvent, and stirred and mixed under heating in a non-oxidizing atmosphere (for example, in a nitrogen atmosphere). Then, the thermoplastic resin is dispersed / dissolved. Alternatively, high-viscosity silicone oil, fluorine oil, thermoplastic resin and, if necessary, organic solvent may be simultaneously or sequentially housed in the reaction vessel (however, the order of each component does not matter) and treated in the same manner as above. good. The concentration of the thermoplastic resin in the heat medium is not particularly limited, but usually 5 to
It is preferably about 50%. Then, the reaction product is cooled, and the solidified thermoplastic resin fine particles are separated and recovered from the heat medium. The method for separating and collecting the thermoplastic resin fine particles is not particularly limited, but for example, an organic solvent that is a non-solvent of the thermoplastic resin and is compatible with the heat medium (for example, aromatic hydrocarbons such as toluene and xylene; trichloroethane). Halogenated hydrocarbons such as; alcohols such as isopropyl alcohol; ethers such as 2-ethoxyethanol; ketones such as methyl ethyl ketone; boiling points such as esters such as ethyl acetate 40 to 200 ° C.
It can be easily carried out by mixing a low-to-medium boiling point solvent) to the reaction product and filtering.

The thermoplastic resin fine particles obtained by the method of the present invention usually have an average particle diameter within the range of about 5 to 30 μm, have a narrow particle diameter distribution, and have a spherical or spherical shape. Such thermoplastic resin fine particles are extremely useful as materials for paints, adhesives, inks, cosmetics and the like.

Effects of the Invention According to the present invention, the following remarkable effects are achieved.

(A) The melted thermoplastic resin is well dispersed in the heating medium, and the adhesion to the vessel wall of the reaction vessel is prevented, so that the desired fine particles can be obtained in good yield.

(B) The particle size of the obtained fine particles is uniform.

(C) The particle shape has a high sphericity.

Examples Examples and comparative examples will be shown below to further clarify the characteristics of the present invention.

Example 1 Pelletized polyamide 12 in a reaction vessel equipped with a cooling tube
35 parts (manufactured by Ube Industries, Ltd.), alcohol-modified dimethyl silicone oil (trademark “YF-3807”, manufactured by Toshiba Silicone Co., Ltd., viscosity at 25 ° C. = 28450 cps) 200
Parts and fluorinated oils (trademark "Daifloyl # 2
0 ″, manufactured by Daikin Industries, Ltd., was housed and heated in a nitrogen atmosphere and under stirring for 2 hours to give 21
It was set to 0 ° C. Hold at the same temperature for 1 hour, polyamide 12
Immediately after melting, the reaction product was poured into 1200 parts of toluene at room temperature with stirring. Next, the fine particles of polyamide 12 obtained by filtering and separating the obtained mixture were washed with n-hexane, filtered again, and the fine particles were dried.

Table 1 shows the viscosity of the heating medium (silicon oil + fluorine oil) at 25 ° C., the heat treatment temperature, and the shape and particle size of the obtained polyamide resin fine particles.

Examples 2 to 4 Thermoplastic resin fine particles were produced in the same manner as in Example 1 except that the following heat medium was used.

The results are also shown in Table 1.

[Example 2]: Dimethyl silicone oil (viscosity 1 million cps) 200 parts Fluorine oil 20 parts [Example 3]: Dimethyl silicone oil (viscosity 1 million cps) 80 parts Dimethyl silicone (viscosity 100 cps) 120 parts Fluorine oil 20 parts [Example 4]: Dimethyl silicone oil (viscosity 1,000,000 cps) 80 parts Aromatic solvent (trademark "Swazol # 1800", manufactured by Maruzen Petrochemical Co., Ltd .; initial distillation 206 ° C, dry point 241 ° C) 20 Part Fluorocarbon oil 20 parts Comparative Examples 1 to 3 Production of thermoplastic resin fine particles was attempted by the same method as in Example 1 except that the following heat medium was used.

The results are also shown in Table 1.

[Comparative Example 1]: 200 parts of alcohol-modified dimethyl silicone oil (viscosity 28500 cps) [Comparative Example 2]: 200 parts of dimethyl silicone oil (viscosity 1000 cps) [Comparative Example 3]: 200 parts of dimethyl silicone oil (viscosity 1000 cps) Fluorine oil 20 parts As is clear from the results shown in Table 1, according to the method of the present invention, fine spherical thermoplastic resin particles having a uniform particle size are obtained.

Claims (2)

[Claims] 1. A method for producing thermoplastic resin fine particles, which comprises melting and dispersing a thermoplastic resin in a heating medium with stirring, cooling it, precipitating it as fine particles, and then separating it from the medium.
Fluorine oil is added, and the viscosity at 25 ° C is 5000 to 1
A method for producing fine thermoplastic resin particles, which comprises using 00000 centistokes high-viscosity silicone oil as a heating medium. 2. The method for producing thermoplastic resin fine particles according to claim 2, wherein the heat medium further contains at least one kind of organic solvent.