JPS6131435A - Preparation of fine thermoplastic resin particle - Google Patents

Abstract

PURPOSE:To control the particle diameter and viscosity distribution and obtain dense spherical fine particles, by mixing a specific medium compound with a thermoplastic resin, adding an EO-PO block copolymer thereto, dispersing the copolymer in the melt state, and the cooling and solidifying the dispersion, and separating the particles. CONSTITUTION:A compound expressed by the formula R-(OCH2XH2)-OR' (R and R' and H or 1-12C branched chain alkyl; n is >=20) is used as a medium compound, and a thermoplastic resin is mixed therewith. A kind of block copolymer consisting of ethylene oxide and propylene oxide is added thereto, and the mixture is mixed and agitated at the melting point or the softening point or above of the respective components to form a dispersion system of the respective components in the melt state. The resultant dispersion system is then cooled to the solidifying point of the thermoplastic resin or below, solidified and separated. An EO-Po block copolymer having 50:50-97:3 weight ratio between the ethylene oxide and propylene oxide is used as the EO-PO block copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Advantages 1"L The present invention relates to a method for producing spherical thermoplastic resin fine particles, and more specifically, to a method for producing spherical fine particles having a dense structure in which the particle size and particle size distribution can be controlled. Regarding manufacturing methods.

fLjin1rhoonJshijshi[1ri3Isurizamariμ8jikemeikakuV
Inuira ζ Man Question - R Quinone J As a method for producing fine particles of thermoplastic resin, there is a method of producing fine particles by suspension polymerization or emulsion polymerization, and after dissolving the polymer in a solvent for a moment, it is Known methods include adding a solvent to precipitate the polymer, heating and dissolving the polymer in a solvent and then cooling it to crystallize and precipitate it, and mechanically pulverizing using a ball mill, jet mill, etc. However, methods for producing polyolefin resins by suspension polymerization, emulsion polymerization, etc. have not yet been established, and methods in which they are precipitated from a polymer solution (for example, see Japanese Patent Publication No. 57-58372)
However, this method has disadvantages in that fine particles with a dense structure cannot be obtained during precipitation, and the particles become porous or homogeneous spherical particles cannot be obtained. On the other hand, in the case of a polyolefin resin having a low melting point or softening point, the mechanical crushing method has limitations such as the fact that the resin becomes soft due to the heat generated during crushing and cannot be crushed as desired.

In addition, the present inventors have previously discovered a method for molding substantially spherical thermoplastic resin fine particles, and have already filed a patent application (Japanese Patent Application
8-121497).

However, it is difficult to control the particle size and particle size distribution only by mechanical stirring, and further technological improvements are required.

Means for Solving the Problems The inventors of the present invention made extensive inquiries in order to overcome the difficulty of the above-mentioned prior art. ' each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, and n is 20 or more) is used as a medium compound, and the medium compound and the thermoplastic Mix the resins, add at least one type of block copolymer consisting of ethylene oxide and propylene oxyl, mix and stir at a temperature higher than the melting point or softening point of each of the components, and disperse the components in a molten state. form a system,
By cooling and solidifying this to below the freezing point of the thermoplastic resin and separating it, we succeeded in molding thermoplastic resin microparticles that were substantially spherical and had a narrow particle size distribution.

Thermoplastic resins suitable for the practice of this invention include polymers and copolymers of olefins such as high and low density polyethylene, polypropylene, polybutylene, polyisobutylene, poly(4-methyl-1-pentene); polyvinyl chloride; , polyvinyl acetate, vinyl chloride/vinyl acetate copolymer, polyvinyl alcohol, polyvinyl acetal, and other vinyl copolymers; ethylene-vinyl acetate, ethylene-vinyl propionate, ethylene-isobutyrate 1-
, ethylene-vinyl alcohol, ethylene-methyl acrylate, ethylene-ethyl acrylate, conylene-ethyl methacrylate, etc.
4-mer; Olefin-allyl copolymers such as ethylene-allyl alcohol copolymers and ethylene-allyl acetate copolymers; Acrylic resins such as polymethyl methacrylate and polyethyl methacrylate; Polyester resins;
Polystyrene resin; Cell 1-1-s, etc. can be mentioned.

As the medium compound of the general formula (1) used in the present invention, polyoxyethylene having a molecular weight of 900 to 100,000 is preferably used, and a suitable molecular weight can be used depending on the type of thermoplastic resin and the melt viscosity. Select and use as appropriate.

Ethyleneoxy I' ([EO) used in the present invention
The -propyleneoxy I' (PO) block copolymer preferably has a molecular weight of 1500 or more and an EO content of 50% by weight or more. More preferably, the molecular weight is 2
000 to 15,000 and preferably has an EO of 80% by weight or more.

In carrying out the method of the present invention, for example, first, the thermoplastic resin, the medium compound, and the EO-PO block copolymer are stirred at a temperature higher than the melting point or softening point of the thermoplastic resin and the medium compound, so that each component is thoroughly mixed. Mix and disperse.

In order to make a polymer into particles, the deformation force of the polymer is F
D. If the force resisting deformation is FC, then FD needs to be larger than FC. Since FG is a force proportional to the relaxation elastic term of the polymer, it varies depending on the type of thermoplastic resin used or the molecular weight of the resin. FD is a force governed by the thermoplastic resin and medium used, and the composition and concentration of the EO-PO block copolymer. Therefore, EO−
The amount of the PO block copolymer added can be appropriately determined depending on the type of thermoplastic resin used and the ratio of EO and PO.

The addition m of the EO-PO block copolymer is, for example, 0.00 m for polyolefin per 100 parts by weight of polyolefin.
The amount can be 1 to 40 parts by weight.

The thermoplastic resin fine particles are composed of a thermoplastic resin, a medium compound, and an E
After sufficiently stirring the O-PO block copolymer under the heating conditions T to mix and disperse the thermoplastic resin in the medium compound, the melting point of the thermoplastic resin is higher than the melting point or softening point of the medium compound. In some cases, the mixture is cooled to a temperature below the melting point of the thermoplastic resin and above the melting point or softening point of the medium compound, and the thermoplastic resin is removed by filtration or the like. II
It can be obtained by separating it from the medium compound and, if necessary, washing with water or a low-boiling organic compound to substantially completely remove the medium compound.

In addition, the mixture of the thermoplastic resin and the medium compound is cooled to below the melting point or softening point of the thermoplastic resin, and one type of organic compound selected from water and a low boiling point organic compound that dissolves the medium compound but does not dissolve the thermoplastic resin. Alternatively, the medium compound and the EO-PO block copolymer can be dissolved and removed by using two or more kinds of compounds. Examples of the low-boiling organic compound include methanol, ethanol,
Examples include acetone. Water is also suitably used, and after dissolving and removing the medium compound and the EO-PO block copolymer with water, the low-boiling point organic compound is added to the thermoplastic 414.
It is also possible to wash away fat particles. The obtained thermoplastic resin particles can be dried according to a conventional method if necessary.

According to the method of the present invention, an inorganic filler is further added to the thermoplastic resin, and this and the medium compound are treated as described above to produce substantially spherical thermoplastic + AI fat composite material particles. can do.

The inorganic filler that can be used for this purpose can be any inorganic filler, and may be surface-treated. Specific examples of such inorganic charging agents include silica, alumina, silica alumina, metal oxides such as iron oxide, chromium oxide, and titanium oxide, talc, calcium carbonate, carbon blank, and metal powders (e.g. iron, aluminum, etc.). ), metal sulfides, clays (kaolinite, zeolite, bentonite, etc.), glass beads, etc. 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 thermoplastic resin composite material 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 a composite agent containing an inorganic filler is produced according to the method of the present invention, the thermoplastic resin, the EO-PO block copolymer, the medium, and the inorganic filler are mixed and stirred according to the method described above. Preferably, the thermoplastic resin and the inorganic filler are mixed in advance.

The mixing ratio of the two can be appropriately selected depending on the desired use of the thermoplastic resin composite material, but the amount of the inorganic filler is generally 70 parts by weight or less per 100 parts by weight of the thermoplastic resin.
Preferably it is in the range of 0.5 to 50 parts by weight.

An example of the use of fine particles produced in this way is a particle size of 5
~20μm is used for cosmetics, toothpaste filling materials, 20~1
00 μm can be used for sintered body materials such as ink rolls and filters, adhesives for bonding inorganic and/or organic substances, binders for inorganic powders, dry coating powders, and the like. Further, it can be suitably used as a packing agent as an organic filler, a solid/I21 lubricant for sliding parts, a column carrier for chromatography, a carrier for supporting an enzyme, and the like. Furthermore, those having an extremely narrow particle size distribution can also be used as spacers to maintain constant intervals between various substances. Also, particles with a particle size of 5 to 20 mm including carbon blank or magnetic powder, etc. Particles of irm can be used as toner for dry copiers.

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.

Harm H? l]1 Low density polyethylene (melting index (190 °c / 2.16 Kg)) in a 500 mQ flask equipped with a stirrer
100g/10m1n) 60g1 polyethylene glycol (molecular weight 20.000) 140g and EO-
PO block copolymer PE-108 (manufactured by Sanyo Kasei Gl,
Molecular weight i 12500. EO: po=so: 20
(weight ratio)) 6g was mixed under nitrogen atmosphere and heated to 200°C.
The mixture was stirred for 60 minutes at an impeller tip speed of 150 m/min.

After a predetermined period of time, the mixture was transferred to a filtration device, and a nitrogen pressure of 7 Kg/c+a was applied at 90°C to remove polyethylene glycol by filtration. Lower the n degree to 50℃,
It was washed with water and methanol to obtain low density polyethylene fine particles. The obtained low density polyethylene fine particles had an average particle size of 1
0 μm and 20 ttm or more particles are 3% by weight,
The shape was spherical.

Example 11 - In Example 1, spherical low-density polyethylene resin particles were obtained in the same manner as in Example 1, except that the EO-PO block copolymer PE-108 was not used. The particle size distribution of the obtained particles is as shown below, and the majority were 111 large particles with a diameter of 100 μm or more.

It is clear from the results of Example 1 and Comparative Example 1 that the particle size can be reduced and the particle size distribution can be narrowed by adding the EO-PO block copolymer.

11 Comparison [ζ The process was carried out in the same manner as in Example 1 except that polypropylene glycol (molecules (J, , 1000) was used instead of the EO-PO block copolymer.The low density polyethylene resin did not form particles, formed a continuum.

1 example of “Harm” - melting index of low density polyethylene 0.4g/10III
The process was carried out in the same manner as in Example 1 except that the particle size was n (190°C/2.16Kg) to obtain spherical low-density polyethylene resin particles.

Ryocho division - 105 μm or less 11% by weight 105 to 250 μm 49% by weight 250 μm or more 40% by weight Comparative example 3 Low density polyethylene melting index Q, 4 g / 10
m1n (190℃/2.16Kg>, EO-
Example 1 except that no PO block copolymer was used
processed in the same way.

Although the particles were spherical, more than 80% by weight of the particles were attached to each other.

Claims (1)

[Claims] 1. General formula (I) R-(OCH_2CH_2)_n-OR'(I) (wherein R and R' each independently represent a hydrogen atom or a carbon number of 1
~12 linear or branched alkyl groups, n
is a number of 20 or more) is used as a medium compound, this medium compound and a thermoplastic resin are mixed, and at least one block copolymer consisting of ethylene oxide and propylene oxide is added thereto. A spherical thermoplastic resin characterized by mixing and stirring at a temperature above the melting point or softening point of the components to form a dispersion system of the components in a molten state, which is then cooled to a temperature below the freezing point of the thermoplastic resin to solidify it and then separated. Method for producing resin fine particles. 2. The method according to claim 1, wherein the weight ratio of ethylene oxide to propylene oxide in the ethylene oxide-propylene oxide block copolymer is 50:50 to 97:3. 3. The method according to claim 1, which uses a thermoplastic resin composite material containing an inorganic filler.