JPS60197734A - Preparation of polyamide resin particles - Google Patents

Abstract

PURPOSE:To provide the titled resin particles in a perfectly spherical form, having a narrow particle size distribution, by dispersing a polyamide resin in a particular medium contg. an anionic surfactant by heating, followed by separating. CONSTITUTION:A polyamide resin (A) (e.g., nylon 6), a medium (B) of the formula (wherein R, R' are H, 1-12C straight-chain or branched alkyl; R'' is H, CH3, C2H5; n is 20 or more) having a MW of 900-1,000,000 (e.g., polyoxyethylene), and 0.1-40% one or more anionic surfactants (C) based on said polyamide resin are mixed with stirring at a temp. of at least the m.p. or softening point of components A and B to disperse well, and then cooled to a temp. of at most the m.p. of the component A and at least the m.p. or softening point of the component B. Then, the component A is separated from the component B, etc. by procedures such as filtering and, if necessary, the component B is completely removed by washing with water or low-boiling org. compds., yielding the titled resin particles.

Description

Detailed Description of the Invention Technical Field The present invention relates to a method for producing spherical polyamide resin fine particles, and more specifically, to a method for producing spherical polyamide resin fine particles, and more particularly to spherical and densely structured polyamide fine particles whose particle size and particle size distribution, particularly particle size distribution, can be controlled. Concerning the manufacturing method.

Methods for producing microparticles of Aratasaka 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, the present inventors have previously discovered a method for producing substantially spherical polyamide resin fine particles, and have already filed a patent application (see Japanese Patent Application No. 147324/1982).

However, in conventional methods, it is difficult to control the particle size distribution using only mechanical stirring, and further improvements in the technology are needed.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing polyamide resin fine particles that are substantially perfectly spherical, particularly having a narrow particle size distribution.

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 compound, this medium compound and a polyamide resin are mixed, and an anionic surfactant selected from among A method for producing fine polyamide resin particles with a narrow particle size distribution, which comprises adding at least one compound to the polyamide resin and mixing and dispersing the medium compound at a temperature higher than the melting point or softening point, and then separating the polyamide resin. provided.

Examples of polyamide resins to which the method of the present invention can be applied include amino acid condensation polyamides, dibasic acid-diamine condensation polyamides, and copolymers thereof. Examples of such polyamide resins include nylon 6, nylon 7, nylon 10, nylon 11. Polymers such as nylon 12, nylon 13, nylon 66,
Nylon 6/12, nylon 6766, nylon 6/1
0. Nylon 6/68/ 6-10. Nice oy6/6T
/6-10. No.

Examples include copolymers such as 6/6T/6I (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.

The medium compound (■) has a molecular weight of 900 to 1.00.
It is preferable to use polyoxine ethylene and polyoxypropylene having a molecular weight of 0.000, and when the polyamide resin has a high melt viscosity, a molecular weight of 10.000 or more is preferable.

Examples of the anionic surfactant used in the method of the present invention include fatty acid salts, higher alcohol sulfate ester salts, fatty acid alcohol phosphate esters, alkylaryl sulfonates, and the like.

In carrying out the method of the present invention, for example, first, a polyamide resin, a medium compound of the general formula (1), and an anionic surfactant are stirred at a temperature higher than the melting point or softening point of the polyamide resin and the medium compound. Mix and disperse thoroughly. The anionic surfactant can be appropriately selected depending on the polyamide resin and medium compound used.

In order to make a polymer into particles, the deformation force of the polymer is F
D. If FG is the force resisting deformation, FD needs to be larger than FG. Since FG is a force proportional to the relaxation elastic term of the polymer, it varies depending on the type of polyamide used. FD is a force governed by the surfactant used. Since FD varies depending on the type of surfactant, some surfactants may be ineffective depending on the type of polyamide.

The selection of such a surfactant is determined in consideration of the HLB (hydrophilic-hydrophobic balance) of the surfactant, zeta potential, influence of steric hindrance of the surfactant, interfacial tension of the polyamide resin used, etc.

The amount of anionic surfactant to be added can be appropriately determined depending on the type of anionic surfactant used. The concentration at which the surfactant exhibits the maximum effect with the minimum amount,
That is, it is well known that the critical micelle concentration (CMC) varies depending on the temperature, type of surfactant, and dispersion medium.

For example, the CMC of sodium lauryl sulfate is 0.2-0.5% by weight in aqueous solution (N, C, Presto
n, J, CCo11oidChe, 52 184 pages (1
94B)) However, as in the method of the present invention,
When used at high temperatures, it is thought that the CMC increases, and in fact, in the method of the present invention, when sodium lauryl sulfate was used, the maximum effect was shown at 0.5 to 20% by weight based on the polyamide resin.

Furthermore, it is common knowledge in the field of surfactants that when the alkyl chain, which is a hydrophobic group, is longer than the lauryl group, the CMC decreases from the above value, and when it becomes shorter, it increases. Generally speaking, the amount of anionic surfactant added can be about 0.1 to 40% based on 100 parts by weight of the polyamide resin.

After the polyamide resin and the medium compound are thoroughly mixed and dispersed under the heating conditions described above, if the melting point of the polyamide resin is higher than the melting point or softening point of the medium compound, the melting point of the polyamide resin and the medium compound are lower than the melting point of the polyamide resin and The mixture is cooled to a temperature above the melting point or softening point, and the polyamide resin is separated from the medium compound by a separation operation such as filtration, and if necessary, it is further treated with water or a low boiling point organic compound as shown below. Washing can substantially completely remove media compounds. The mixture of the polyamide resin and the medium compound is cooled to below the melting point or softening point of the polyamide resin, the medium compound represented by the general formula (I) is dissolved, and water and low-boiling organic compounds that do not dissolve or swell the polyamide resin are dissolved. The polyamide resin fine particles can also be separated by dissolving and removing the medium compound and the anionic surfactant using one or more selected compounds. Examples of the low-boiling organic compound include methanol, ethanol, acetone, and the like. Water is also suitably used, and after dissolving and removing with water, washing with a low-boiling organic compound may be carried out. The obtained particles can be dried according to a conventional method if necessary.

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

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, iron oxide, chromium oxide,
Examples include metal oxides such as titanium oxide, talc, calcium carbonate, carbon blank, metal powders (e.g. iron, aluminum, etc.), metal sulfides, clays (kaolinite, zeolite, bentonite, etc.), glass peas, etc. . There are no particular limitations on the particle size or shape of the inorganic filler used, but the particle size is preferably 1/1O or less of the target particle size of the polyamide resin composite to be manufactured, and is 1150 or less. is 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 material 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. The mixing ratio of both can be appropriately selected depending on the desired use of the polyamide resin composite material, but
The amount of the inorganic filler blended is generally 70 parts by weight or less, preferably in the range of 0.5 to 50 parts by weight, based on 100 parts by weight of the polyamide resin.

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, and bases for cosmetics. It can be suitably used for.

Below, 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 In a 11 flask equipped with a stirrer, nylon-1230
g, polyethylene glycol (molecular weight 20.000) 7
0 g and 1.5 g of sodium lauryl sulfate were mixed under nitrogen atmosphere and stirred at 240°C for 60 minutes at 11000 rpm. After a predetermined period of time, the mixture is transferred into a filtration device 170
℃ to remove polyethylene glycol by filtration under nitrogen pressure of 7 kg/-, then lower the temperature to 50℃, water,
After washing with methanol, spherical fine particles of nylon-12 were obtained. The particle size distribution of the obtained polyamide fine particles was as shown in FIG.

Example 2 Spherical polyamide resin particles were obtained in the same manner as in Example 1 except that the amount of lauryl sulfate added was 0.3 g. The particle size distribution of the obtained particles was as shown in FIG.

Comparative Example 1 Spherical polyamide resin particles were obtained in the same manner as in Example 1 except that sodium lauryl sulfate was not used. The particle size distribution obtained was as shown in FIG.

Example 3 Spherical polyamide resin particles were obtained in the same manner as in Example 1 except that nylon 6 was used instead of nylon 12. The particle size distribution obtained was as shown in FIG.

Comparative Example 2 Spherical polyamide resin particles were obtained in the same manner as in Example 3 except that sodium lauryl sulfate was not used. The particle size distribution of the obtained particles was as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the particle size distribution of polyamide particles obtained in Examples 1 and 2 and Comparative Example 1. FIG. 2 is a graph showing the particle size distribution of polyamide particles obtained in Example 3 and Comparative Example 2. 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, 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 compound, this medium compound and a polyamide resin are mixed, and an anionic surfactant selected from among at least 1
A method for producing fine spherical polyamide resin particles with a narrow particle size distribution, which comprises adding a seed compound, mixing and dispersing the polyamide resin and a medium compound at a temperature higher than the melting point or softening point, and then separating the polyamide resin.