JPS58219240A - Production of fine spherical, particles of thermoplastic resin - Google Patents

Abstract

PURPOSE:A mixture of a thermoplastic resin and a nonsolvent of the resin is stirred at a temperature higher than the flow point to form a suspension of the melted resin, then cooled to give fine, spherical particles of the thermoplastic resin. CONSTITUTION:A thermoplastic resin such as polyethylene is mixed with a nonsolvent such as silicone oil and heated up to a temperature higher than the flow point of the resin, preferably 20-70 deg.C higher than the point to form a suspension of the melted resin in the nonsolvent. Then, the suspension is rapidly cooled, preferably by mixing the suspension with cold nonsolvent to give the objective fine spherical particles. EFFECT:The resultant particles have smooth surfaces, high roundness, a narrow particle size distribution and high fluidity. USE:As a cosmetic base, coating, or in powder molding or rotational molding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing thermoplastic resin spherical fine particles. Specifically, the present invention relates to a method for producing fine, perfectly spherical thermoplastic resin particles that are advantageous for all industries.

As a method for producing fine particles of thermoplastic resin, a method of precipitating a thermoplastic resin by cooling a heated solution of thermoplastic resin, or a method of mixing a solution of thermoplastic resin and a non-solvent of thermoplastic resin There are methods known to precipitate thermoplastic resins, such as the method of precipitating thermoplastic resins by using resin, but these methods require time to dissolve the thermoplastic resins in a solvent, and the processing lid is determined by the solubility of the resin. However, this method was not completely satisfactory, as the amount of solvent used could not be increased.

As a result of extensive research into the production of thermoplastic resin fine particles, the present inventors found that when stirring a mixture of a thermoplastic resin and a non-solvent of the resin at a temperature equal to or higher than the pour point of the resin, The present invention was completed based on the discovery that a suspension of spherical molten resin suspended in a non-solvent is formed, and by cooling this suspension, true spherical resin particles can be obtained.

That is, the present invention aims to efficiently produce true spherical resin fine particles with easy operation.The purpose of the present invention is to stir the thermoplastic resin at a temperature higher than the pour point of the thermoplastic resin, so that the melt of the thermoplastic resin is dissolved in the non-solvent. This is accomplished by forming a suspended suspension followed by cooling.

The present invention will be explained in detail below.

Thermoplastic resins used in the present invention include polyolefins such as polyethylene and polypropylene, vinyl resins such as polystyrene, polyvinyl chloride, polyacrylate, and polymethacrylate, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and nylon 6. , nylon tt, f-i, lon 6/6, nylon //, polyamide such as nylon 7.2,
Examples include polycarbonate.

In the present invention, the pour point, that is, the melting point for crystalline resins and the softening point for amorphous resins, is 300'
O or less, preferably 2! It is better to select a tube with a melt viscosity of about θC or less, and the melt viscosity is 10,000 or less, preferably Idj000 or less, more preferably - θO0.
It is best to choose one that is below the level of bois.

The non-solvent for the thermoplastic resin should have a boiling point higher than the pour point of the thermoplastic resin, preferably higher than the pour point above.
It has a boiling point as high as θ0 or more in summer, does not dissolve the target thermoplastic resin even at a temperature higher than the pour point, and
It is preferable to choose a material whose viscosity at high temperatures is 10 cmV or 11''·s or more, and whose viscosity is 30-!tOθθcmV or higher (see the pour point above).

Non-solvents with boiling points lower than the pour point of the thermoplastic resin in question are not impossible to use, but are not advisable as they require pressurization to raise the temperature.

As the non-solvent for the thermoplastic resin, one that satisfies the above conditions may be selected depending on the type of the target thermoplastic resin.
Typical examples include silicone oil, liquid paraffin, mineral oils such as lubricating oils, and hydrocarbons such as decane, undecane, dodecane, tetradecane, and hexadecane.

In the present invention, a thermoplastic resin and a non-solvent are mixed,
Stirring is performed at a temperature above the pour point of the thermoplastic resin to form a suspension in which the molten resin is suspended.

The mixing ratio of the thermoplastic resin and the non-solvent may be such that the molten resin can be suspended as a dispersed phase. Usually, the ratio of the thermoplastic resin to the non-solvent is θ, θ/~/! amount times, preferably O
It is preferable to select from a range of about 0θλ to o3 times the weight. The small amount of hair in the thermoplastic resin is not inconvenient in practice, but the amount of treatment is small relative to the amount of non-solvent, so it is not a good idea. There is no particular restriction on the device as long as it can perform sufficient stirring, and it may include a container containing a heater such as a jacket type or coil type, and various types of stirrers, such as
Examples include devices that combine a fan turbine type, disc turbine type, 7-audler type, propeller type, anchor type, and other stirrers.

The temperature at which the molten resin forms a suspension is:
It is advisable to select a temperature that is about υ/00 or more higher than the pour point of the thermoplastic resin used, preferably about 700 or more. If the temperature is too low, the resin will not be sufficiently melted and dispersed.

On the other hand, if it is too high, there is a risk of deterioration of the resin.

Stirring has a large effect on the particle size of the molten resin in the suspension; rapid stirring will reduce the particle size, while slow stirring will increase the particle size.

The particle size of the molten resin varies depending on the type and quantitative ratio of the thermoplastic resin and nonsolvent, temperature, type of equipment, and other conditions, so the stirring speed should be adjusted to achieve the desired particle size, including these conditions. For example, if you use silicone oil as a non-solvent and a fan-turbine type stirrer, the particle size will be a few microns. When trying to obtain a product of about θμ, it is preferable to select a rotation speed from the range calculated from the following formula depending on the diameter of the stirrer.

Similarly, when trying to obtain a product with a diameter of about /θθ~200μ, the following range is preferable.

The heating and stirring time is generally several minutes to several tens of minutes, specifically about 20 minutes after reaching the above temperature.

The suspension formed by heating and stirring is cooled to solidify the molten resin to form fine resin particles. The means of cooling is not particularly limited, but rapid cooling is preferable because it reduces the chances of fusion of the molten resins and shortens the time. A suitable method is to completely lower the temperature by mixing with

In the method of the present invention, when the raw thermoplastic resin is added under stirring to the non-solvent heated to a temperature higher than the pour point of the raw thermoplastic resin, the resin immediately melts to form a suspension. When this suspension is mixed with a separately prepared non-solvent at a low temperature and cooled, the result is 1! can produce fine resin particles in an extremely short period of time, and can easily be made into fine particles for resins that are concerned about changes in polymerization degree or deterioration due to heating.

When using the method of the present invention such as ν filtration or centrifugation, fine thermoplastic resin particles with particle sizes ranging from about ioμ to about /μ can be easily produced from the suspension after cooling. Since there is no need to dissolve it in a solvent, a large amount of thermoplastic resin fine particles can be produced in a short time. Furthermore, the particle size can be controlled by classifying as necessary.

The thermoplastic resin fine particles produced by the method of the present invention have a smooth surface, a true spherical shape, a narrow particle size distribution, and good fluidity, so they are suitable for cosmetic bases, paints, powder molding, rotary molding, etc. It is.

EXAMPLES The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Implementation / In a flask with a fan turbine type stirrer with blade diameter / θ, put 00rrrtf in silicone oil and add 26θ
While stirring at a speed of 200 rpm, add nylon 6 (manufactured by Mitsubishi Chemical Industries, Ltd.) to relative viscosity.
30 g of pellets (Trademark: Tsubamitsu 10/θ) were added.

The entangled nylon immediately melted and dispersed to form a suspension.

After 5 minutes, this suspension was mixed with room temperature silicone oil/l-f while stirring vigorously, and the liquid temperature was /3
C, the nylon dispersed and solidified as expected.

This mixture'f! : The solidified nylon was separated by filtration using a millipore filter, washed with n-hexane, and dried.

When the obtained nylon was observed under a microscope, it was found to be perfectly spherical fine particles with a smooth surface, and the particle size was 30 μm.

Nylon with a relative viscosity of 7, 2 (manufactured by Emsar, trademark, Grilamid L/≦
) was used to prepare the suspension at 1.230'O, but cooling was carried out in the same manner as in Example/. The temperature after cooling is /
It was θ-20.

The mixture was filtered using a /μ Millipore filter to separate the solidified nylon, washed with toluene and dried.

When the obtained nylon was observed under a microscope, it was found to be true spherical fine particles with a clean and strong surface, and the particle size was 1.2~.
It was 2oμ.

Example 3 A stirrer (manufactured by Tokushu Kika Kogyo ■, trademark, Pomo mixer HV-M type) was set in a 2-t separable flask, and 00 ml of silicone oil was poured into the flask, heated to 23θ'C, and homomixer While stirring at a rotational speed of 0000 rpm, the same nylon/component used in Example
30! ! All additions were made and stirred for 70 minutes.

Next, when I poured room temperature silicone oil/l into this, the liquid temperature was /! 0, and the nylon solidified while remaining dispersed.

This mixture was filtered using a /μ Millipore filter to separate solidified nanoparticles, washed with toluene, and dried.

When the obtained nylon was observed under a microscope, it was found to be true spherical fine particles with a clean surface, and the particle size was /~/θμ.

Example 1/1 flask having a turbine blade stirrer with blade diameter α,
Add 600 ml of dodecane and raise the temperature to θ゛C in the evening.
While stirring at a rotational speed of 0θθ rpm, polyethylene with a melt index of 80 (Mitsubishi Chemical Industries mA, trademark, Tubatic ITθ/I01) was added to form a suspension of molten polyethylene.

After 5 minutes, room-temperature dodecane 2 was poured into the suspension while being vigorously stirred, and the liquid temperature became 0, and the polyethylene solidified while being dispersed.

This mixture f10μ sintered metal filter? The solidified polyethylene was separated, washed with hexane, and dried.

When the obtained polyethylene was observed under a microscope, it was found to be fine particles with a clean surface and a perfect spherical shape, and the particle size was /θ
~! It was θμ.

Example 1-i In Example 1, the rotation speed of the fan turbine type stirrer '
ff: The following results were obtained by carrying out the same procedure except for changing.

Applicant: Mitsubishi Chemical Industries, Ltd. Agent Patent Attorney Hase - (7 others)

Claims (3)

[Claims] (1) A mixture of a thermoplastic resin and a non-solvent for the core thermoplastic resin is stirred at a temperature equal to or higher than the pour point of the thermoplastic resin, so that the melt of the thermoplastic resin is suspended in the non-solvent. A method for producing thermoplastic resin spherical fine particles, which comprises forming a liquid and then cooling it. (2) A patent claim characterized in that a suspension is formed by adding a thermoplastic resin to a non-solvent of the resin that is heated to a temperature equal to or higher than the pour point of the resin and stirred. A method for producing thermoplastic resin spherical fine particles according to item +1). (3) Cooling is carried out by mixing a molten thermoplastic resin suspension with a non-solvent of #resin. )
A method for producing thermoplastic resin spherical fine particles as described in Section 1.