JPS60197735A - Preparation of polyamide resin particles - Google Patents

Abstract

PURPOSE:To provide the titled resin particles having a dense structure in a spherical form, with strictly controlled particle sizes, by dispersing a polyamide resin in a particular medium contg. a polybasic acid by heating, followed by separating. CONSTITUTION:10pts.wt. or less one or more polybasic acids (e.g., sulfuric acid) are added to 100pts.wt. mixture of a polyamide resin (A) (e.g., nylon 6) with a medium (B) of the formula (wherein R, R' are H, 1-12C straight-chain or branched alkyl; R'' is H, CH3, C2H5) are mixed with stirring at a temp. not less than the m.p. or softening point of components A and B to disperse well. Thereafter, by cooling to a temp. not more than the deposition temp. of said polyamide and operating filtration and the like, the component A is separated from the component B and, if necessary, the component B is completely removed by washing with water or low-boiling org. compds., yielding the titled resin particles with a particle size of 10mum or below.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for producing spherical polyamide resin microparticles, and more specifically, a production method that allows strictly controlling the particle size of substantially spherical polyamide resin microparticles having a dense structure. Regarding.

1. Methods for producing microparticles of unexplored moldy thermoplastic resin include a method of producing microparticles by suspension polymerization or emulsion polymerization, a method of dissolving a polymer in a solvent, and then adding a non- or poor solvent thereto for precipitation. A method in which a polymer is heated and dissolved in a solvent and then cooled to crystallize and precipitate, and a method in which the polymer is mechanically pulverized using a ball mill, a jet mill, etc. are known. However, methods for producing polyamide resin by suspension polymerization, emulsion polymerization, etc. have not yet been established, and methods in which they are precipitated from a polymer solution do not yield fine particles with a dense structure during precipitation, resulting in porous particles. However, there were disadvantages in that homogeneous spherical particles could not be obtained. Furthermore, it goes without saying that it is extremely difficult to precisely control the particle size of spherical polyamide resin using conventional techniques.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide an innovative method for producing polyamide resin fine particles that are substantially completely spherical and whose particle size can be arbitrarily and strictly controlled. It is in.

Structure of the Invention According to the present invention, the general formula (I) (wherein R and R' are each independently a hydrogen atom or a straight or branched alkyl group having 1 to 12 carbon atoms, R''
is a hydrogen atom or a methyl or ethyl group, and n is a number of 20 or more) is used as a medium, and this medium compound, a polyamide resin, and a polybasic acid are mixed at the melting point or softening point of the polyamide resin and the medium compound. There is provided a method for producing spherical polyamide resin fine particles, which comprises stirring at the above temperature to sufficiently mix and disperse, cooling to a temperature below which the polyamide precipitates, and then separating the polyamide resin from the medium.

Detailed explanation of the structure and effects of the invention The present inventors have previously discovered a method for producing substantially spherical polyamide resin fine particles, and have already filed a patent application (Japanese Patent Application No. 5
8-147324 specification WA). The present inventors further investigated this method and found that polybasic acids such as sulfuric acid, sulfurous acid, sulfonic acid, fuming sulfuric acid, and phosphoric acid are very effective in making thermoplastic resins fine particles. That is, by using these polybasic acids, it is possible to efficiently obtain microparticles with a particle diameter of 108 m or less, which cannot be obtained by conventional methods. In order to obtain particles with a particle diameter of 10 μm or less by mere mechanical stirring, high-speed stirring of 10 GO rpm, preferably 5000 rpm or more is required, but in this case, a special high-speed stirring device is required, and the stirring speed is also high. It requires a lot of power. Moreover, even if such a device is used, particles p
I! According to the method of the present invention, all particles can be reduced to 10 μm or less by using the polybasic acid, and further, by adding the polybasic acid. By adjusting the amount, the particle size of the particles can be adjusted as desired. That is, when the amount of polybasic acid added is increased, the particle size of the resulting polyamide resin particles becomes smaller, and conversely, when the amount is decreased, the particle size becomes larger.

Incidentally, the particle size distribution described in the following examples was measured using a Coulter counter (Nikkaki ■).

Polyamides to which the method of the present invention can be applied include amino acid condensation type polyamides, dibasic acid-diamine condensation type polyamides, and copolymers thereof. For example, polymers such as nylon 6, nylon 7, nylon IO, nylon 11, nylon 12, nylon 13, nylon 66, nylon 6/12, nylon 6/66, nylon 6/
1G, nylon 6/66/6-10, nylon 6/6T
/6-10, nylon 6/6T/61 (T represents a terephthalic acid component, and ■ represents an isophthalic acid component). The method of the present invention can also be applied to block copolymers or mixtures of two or more of these polyamides, or block copolymers or mixtures with other polymers other than polyamides.

Media compounds (with molecular weights of 900 to i, ooo
, ooo polyoxyethylene and oxypropylene are preferably used, and when the aforementioned polyamide resin has a high molecular weight, the molecular weight of the medium compound is 10.0.
It is suitable that it is 00 or more.

Examples of polybasic acids used in the method of the present invention include sulfuric acid, sulfurous acid, sulfonic acid, and fuming sulfuric acid. The use of the above acids is not limited to only one type;
More than one species can also be used together.

In carrying out the method of the present invention, for example, first, the polyamide resin and the medium compound of the general formula (1) are stirred at a temperature higher than the melting point or softening point of the polyamide resin and the medium compound to sufficiently mix and disperse. The polybasic acid may be added to the medium compound in advance, or may be added after the polyamide resin and the medium compound are mixed and dispersed. The amount of polybasic acid added is generally 10 parts by weight or less per 100 parts by weight of the mixture of polyamide resin and medium compound, and varies depending on the mixing ratio of the former and the type of acid, but for example,
When the mixing ratio of the polyamide resin and the medium compound is 2:8, the mixture of the polyamide resin and the medium compound is 10
Suitable amounts are 0.01 to 3 parts by weight for sulfuric acid and 0.03 to 4 parts by weight for sulfonic acid.

The mixture of the polyamide resin, the medium compound, and the polybasic acid is mixed and dispersed by thorough stirring under the heating conditions described above, and if the melting point of the polyamide resin is higher than the melting point or softening point of the medium compound, the polyamide resin The mixture is cooled to a temperature below the melting point of the fat and above the melting point or softening point of the medium compound, and the polyamide resin is separated from the medium compound and polybasic acid by performing a separation operation such as filtration, and further as necessary. , water, or a low boiling organic compound such as those shown below to substantially completely remove the media compound. Another method is to cool the mixture of the polyamide resin and the medium compound to below the melting point or softening point of the polyamide resin, dissolve the medium compound represented by the general formula (1), and use water that does not dissolve the polyamide resin and/or The polyamide resin fine particles can also be separated by dissolving and removing the medium compound and the polybasic acid using one or more compounds selected from boiling-point organic metal compounds. Examples of the low-boiling organic compound that can be used include methanol, ethanol, acetone, benzene, ethyl acetate, cellosolve, carbon tetrachloride, and chloroform. The particles thus obtained can be dried by a conventional method if necessary.

According to the method of the present invention, an inorganic filler is further blended into the polyamide resin, and this is treated with the medium compound of the general formula (1) and the polybasic acid as described above to produce a substantially spherical polyamide resin composite. fine particles can be produced.

Any inorganic filler can be blended as the inorganic filler used for this purpose, and one that has been surface-treated may be used. Specific examples of such inorganic fillers include silica, alumina, silica alumina, metal oxides such as iron oxide, chromium oxide, and titanium oxide, talc, calcium carbonate,
Examples include carbon black, metal powder (for example, iron, aluminum, etc.), metal sulfide, clays (kaolinite, montmorillonite, bentonite, etc.), glass beads, and the like. There are no particular limitations on the particle size or shape of the inorganic filler used, but the particle size is preferably 1/10 or less of the target particle size of the polyamide resin composite material to be manufactured, and preferably 115° or less. Particularly preferred. The above-mentioned inorganic fillers can be used alone or as a mixture of two or more, and organic dyes such as azo dyes, red iron oxides, and phthalocyanine-based dyes can also be used in combination.

When producing a composite agent containing an inorganic filler according to the method of the present invention, it is desirable to mix the polyamide resin and the inorganic filler in advance, but it is also possible to add the polyamide resin, medium, polybasic acid, etc. at the same time. do not have. The mixing ratio of the two can be appropriately selected depending on the desired use of the polyamide resin composite material, but the amount of the fR machine filler is generally 70 parts by weight or less, preferably 5 parts by weight, based on 100 parts by weight of the polyamide resin.
It is in the range of 0 parts by weight or less. The amount of polybasic acid added can be exactly the same as when no inorganic filler is added.

Substantially spherical polyamide resin fine particles produced in this manner can be used as powder coating paints, solid lubricants for sliding parts, column carriers for chromatography, carriers such as enzyme carriers, bases for cosmetics, etc. by various methods. It can be suitably used for.

Takumi K1 Hereinafter, the present invention will be explained in more detail according to examples.
It goes without saying that the scope of the present invention is not limited to these Examples.

Example 1 Polyethylene glycol (molecular weight 20.000) 70 under nitrogen atmosphere in a 300 ml flask equipped with a stirrer
3 parts by weight and 0.6 parts by weight of a 40% sulfuric acid aqueous solution at 90°C.
Mixed for 0 minutes. Next, nylon 12 (molecular weight 14.0
00) Add 30 parts by weight, raise the temperature to 200°C,
The mixture was stirred at 00° C. for 60 minutes at a stirring speed of 11,000 rpm and then cooled to room temperature. The resulting mixture was heated to 150° C. to melt the polyethylene glycol, a pressure of 7 kg/cIa was applied under a nitrogen atmosphere, and nylon 12 was separated by filtration. The nylon 12 on the filter was washed with warm water or methanol to dissolve and remove polyethylene glycol and sulfuric acid adhering to the surface of the nylon 12 particles. In this way, spherical nylon 12 particles were obtained. The particle size distribution of the obtained particles was as shown in FIG. In addition, the particle diameter was measured using a Coulter counter.

Example 2 The same operation as in Example 1 was performed except that the amount of 40% sulfuric acid added was 0.1 parts by weight. Obtained spherical nylon 1
The particle size distribution of the two particles was as shown in FIG.

1 Milk 1 The same procedure as in Example 1 was performed except that 40% sulfuric acid was not used. The particle size distribution of the obtained particles was as shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a graph showing the particle size distribution of polyamide particles obtained in Examples 1 and 2 and Comparative Example 1. Patent Applicant: Showa Denko Co., Ltd. Patent Application Agent: Akira Aoki, Patent Attorney: Kazuyuki Nishidate, Patent Attorney: Ishi 1) Patent Attorney: Akiyuki Yamaguchi, Patent Attorney: Masaya Nishiyama

Claims (1)

[Claims] 1. General formula (1) (wherein R and R' are each independently a hydrogen atom or a straight or branched alkyl group having 1 to 12 carbon atoms, RI
I is a hydrogen atom or a methyl or ethyl group, n is a number of 20 or more) is used as a medium,
The medium compound, the polyamide resin, and the polybasic acid are sufficiently mixed and dispersed by stirring at a temperature higher than the melting point or softening point of the polyamide resin and the medium compound, and then cooled to a temperature lower than the temperature at which the polyamide precipitates. A method for producing spherical polyamide resin microparticles, which comprises then separating the polyamide resin from a medium.