JPH01158042A - Production of spherical fine powder of polymer - Google Patents

Abstract

PURPOSE:To obtain the title fine powder in a short time in high efficiency at a low cost, by emulsifying a solution of a thermoplastic polymer in the form of an O/W-type emulsion, evaporating the organic solvent under agitation and separating the powder from the emulsion. CONSTITUTION:(A) A thermoplastic polymer is dissolved in (B) an organic solvent to obtain a polymer solution. (C) Water containing an emulsifier is added to the solution under agitation to form an O/W-type emulsion via a W/O-type emulsion. The component B is evaporated from the resultant emulsion under agitation and the objective fine powder is separated from the emulsion. The component B is preferably a solvent having a boiling point of <100 deg.C and essentially hardly soluble or insoluble in water (e.g., benzene). The compo nent C is preferably a protective colloid substance (e.g., polyvinyl alcohol) and the component A is preferably selected from aromatic polysulfone resin, amor phous nylon and amorphous polyarylate and the polymer solution preferably contains a thermosetting resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing fine spherical thermoplastic polymer powder.

[Prior art] Methods for producing thermoplastic polymer particles include A) mechanical pulverization using a ball mill, jet mill, etc., B) spray drying, C) emulsion polymerization, nonaqueous dispersion polymerization, seed emulsion polymerization, and suspension polymerization. A method of polymerizing a polymerizable monomer into particles using a polymerization method such as turbid polymerization, D) After dissolving the polymer in a solvent at a high temperature higher than its glass transition temperature or melting point,
A method of crystallizing the polymer by cooling; E) a method of precipitating the polymer by dissolving the polymer in a solvent and then adding and mixing a solvent that is a poor solvent for the polymer and is compatible with the solvent for the polymer; F) A polymer solution obtained by dissolving a polymer in a solvent is added and mixed into a solvent that is a poor solvent for the polymer and is incompatible with the solvent for the polymer, and is strongly stirred to form a dispersed state, and then the dispersion is prepared. A method is known in which the solvent inside is removed and the polymer is taken out.

Among the above A-F, F is a method that can be classified as a chemical pulverization method and is relatively easy to obtain spherical polymer particles.
For example, Japanese Patent Publication No. 61-28688, Japanese Patent Application Laid-Open No. 1728-1982, and Japanese Patent Application Laid-open No. 62-3212.
This is disclosed in Publication No. 4, etc.

[Problems to be Solved by the Invention] However, it is difficult to easily form thermoplastic polymers into spherical particles by mechanical pulverization using method A);
Methods B) to E) also had problems such as poor economic efficiency, poor reproducibility, and difficulty in obtaining spherical particles.

Furthermore, chemical pulverization methods such as the F method require the formation of an O/W type emulsion from the beginning of dispersion.
This poses various problems. That is, in order to obtain spherical fine powder with a small particle size, it is necessary to significantly lower the viscosity of the polymer solution, which requires the use of a large amount of organic solvent, which increases the size of the equipment for recovering the organic solvent. This method has drawbacks such as a long distillation time for the solvent and complicated stirring conditions.

In particular, the viscosity of the polymer solution of the thermoplastic polymer applied to the present invention is extremely high, and it is difficult to obtain a substantially spherical fine powder using method F).

As described above, it is still difficult to stably obtain spherical fine powder from thermoplastic polymers, and the present invention
An object of the present invention is to provide a method for producing fine spherical polymer powder, which can be produced stably and economically in a short time even when using a highly viscous polymer solution.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

``A method for producing fine spherical polymer powder, characterized by comprising the following steps (a) to (d).

(a) A thermoplastic polymer is dissolved in an organic solvent to obtain a polymer solution.

(b) Water containing an emulsifier is added to the polymer solution under stirring to emulsify the polymer solution through a water-in-oil (W/O) emulsion to an oil-in-water (O/W) emulsion. .

(c) While stirring the emulsion, the organic solvent contained in the emulsion is evaporated.

(d) Take out spherical polymer fine powder from the emulsion. ” The thermoplastic polymer applied to the present invention is preferably water-insoluble, has a glass transition temperature (Tg) of at least the main component of 30°C or higher, and is soluble in the organic solvent described below. , styrene resin, vinyl resin, polyester resin, cellulose derivative monolith, polyacetal, polycarbonate, polyphenylene oxide, etc., but are not limited thereto. These polymers may be used alone or in combination of two or more.

If the Tg of the main component polymer is lower than 30° C., there is a possibility that the finally obtained fine polymer powder will cause fusion.

In particular, among these polymers, it is preferable to select from aromatic polysulfone resins, amorphous nylon, and amorphous polyarylates because they have excellent heat resistance and toughness. Considering heat resistance and toughness, these polymers have a crystal fusion heat of 5Ca measured with a differential scanning calorimeter.
It is preferably 1/g or less and 2 or less, and more preferably 1 c
It is preferable that it is below al/g. Further, the glass transition point temperature is also preferably 150°C or higher.

The aromatic polysulfone resin is a resin having a diallyl sulfone group in the molecule as a structural unit,
Specific examples include polysulfone, polyethersulfone, polyallylsulfone, etc., but are not limited thereto.

These can be synthesized as needed, or commercially available ones can be used. Commercially available products include Needel (Union Carbide) and Pictrex (
ICI Co., Ltd.) Astrel (Carporundum Co., Ltd.)
, Sedel (Union Carbide Company), etc. are known.

Amorphous nylon is a nylon that provides transparent molded products regardless of thickness under normal melt molding conditions, and that does not cause devitrification due to post-crystallization even during heat treatment and hot water treatment. Yes, in order to satisfy these characteristics,
Isophthalic acid, terephthalic acid, metaxylylene diamine, 1,3-bisaminomethylcyclohexane, isophorone diamine, 2.2.4- or 2,4.4-trimethylhexamethylene diamine, 4,4°-diaminodicyclohexylmethane , 4.4°-diamino-3,3′-dimethyldicyclohexylmethane, and 4,4°-diaminodicyclohexylpropane. These can be synthesized depending on the required properties, or commercially available transparent nylon (the amorphous nylon of the present invention is generally called transparent nylon) can be used. As a commercially available product, TROGAMID-T (Dyn
amit Nobe1), ZY-330 (Du
Pont Co.), GRI LAM ID
-TR55 (Emser Werke) etc. are known.

Amorphous polyarylates are usually obtained by polycondensation of dihydric phenols and aromatic dicarboxylic acids, and dihydric phenols include bisphenol A.
, bisphenol F, and their alkyl substituted products, and the aromatic dicarboxylic acids include, but are not limited to, terephthalic acid and isophthalic acid. These can be synthesized depending on the required characteristics, or commercially available ones can be used. Commercially available products include U Polymer (Unitika),
Adel (UCC), Arilev (Solvay), APR
(Bayer), Durrell (Celanese), Arilon (DuPont), NAP resin (Kanebuchi Chemical Industry), etc. are known.

The organic solvent used in the present invention may be any organic solvent as long as its main component is substantially insoluble or sparingly soluble in water and has a boiling point of less than 100°C.

Organic solvents that satisfy these characteristics include hydrocarbons such as pentane, hexane, heptane, benzene, cyclohexane, petroleum ether, methylene chloride, chloroform,
Examples include dichloroethane, dichloroethylene, 1,1,1-trichloroethane, trichloroethylene, halogenated hydrocarbons such as carbon tetrachloride, ethers such as diethyl ether, esters such as ethyl acetate, and ketones such as methyl ethyl ketone. A mixture of more than one species may be used. Furthermore, in order to further improve the solubility of the thermoplastic polymer in the above organic solvent, it is also possible to use a small amount of an organic solvent that is miscible with water. The method of the present invention can be operated without problems if at least 60% by weight of the organic solvent used is insoluble in water.

The organic solvent used is appropriately selected depending on the type of polymer, and the amount thereof is such that the viscosity of the polymer solution at the start of emulsification is preferably 0.1 to 800 poise, more preferably 10 to 500 poise, and even more preferably 50-30
It is determined to be within the range of 0 poise.

When the viscosity of the polymer solution during emulsification is less than 0.1 poise, the amount of organic solvent in the polymer solution becomes relatively large.
As a result, it is highly likely that the time required to distill off the solvent will become longer. Furthermore, since the O/W is made into an emulsion, the amount of water added inevitably increases, which may make recovery complicated. Furthermore, coalescence between particles may occur during the emulsification operation or during the solvent and volatilization operation, resulting in non-spherical particles or cream-like particles, which may prevent the emulsion from being obtained.

On the other hand, if the viscosity of the polymer solution during emulsification exceeds 800 voids, the polymer solution will become very viscous, which will place a heavy load on the stirring device and may prevent smooth emulsification.

There is no particular problem as long as the temperature during emulsification is below the boiling point of water.
Preferably, the temperature is below the boiling point of the main component organic solvent.

In the method of the present invention, protective colloidal substances are preferably used as emulsifiers. Specific examples of the protective colloidal substance include polyvinyl alcohol, carboxymethyl cellulose, hydroxy 10-pyl cellulose, hydroxyethyl cellulose, modified starch, polyvinylpyrrolidone, gelatin, gum arabic, and casein. In addition to the above protective colloidal substances, nonionic, anionic and cationic surfactants may be used in combination, if necessary. Furthermore, a surfactant may be added to the polymer solution as long as it does not reduce the solubility of the polymer. Furthermore, it is also possible to add alcohol to water and use a mixed water/alcohol solution as the added water, as long as the protective colloidal substance does not precipitate.
' Water containing a protective colloidal substance (surfactant if necessary) is added continuously or intermittently to the polymer solution being stirred at a predetermined speed.

The final amount of water added is 50
Overlapping fire or higher is preferable. A feature of the present invention is that water is added to a relatively highly viscous polymer solution, and initially W10
After a type emulsion is formed, a solvent-containing polymer emulsion having a predetermined particle size is obtained by inverting the phase to an O/W type emulsion while increasing the amount of water added. When a polymer solution is added to water under stirring in the prior art, only lumps or fibers are obtained when a relatively highly viscous polymer solution is added. In order to obtain spherical fine particles using the conventional method, it is necessary to use a dilute polymer solution, and therefore a large amount of solvent must be distilled off, which is very inefficient. Furthermore, in the case of the present invention, the amount of water used can be much smaller than in conventional chemical pulverization methods, and dehydration and drying can be performed more efficiently.

The organic solvent in the obtained emulsion is removed by evaporation by heating the emulsion at a temperature of less than 100° C. while stirring the emulsion and, if necessary, reducing the pressure. In the case of the present invention, since the amount of organic solvent in the emulsion is relatively small, bumping of the emulsion is not observed even when heated above the boiling point of the organic solvent, and the solvent can be smoothly removed.

In the case of the conventional chemical pulverization method, since a large amount of organic solvent is used, it is necessary to heat the material at a temperature at or below the boiling point of the organic solvent, and therefore, it is inefficient in this respect as well.

Stirring the emulsion is important in order to volatilize and remove the organic solvent more efficiently.

The emulsion from which the organic solvent has been removed is filtered or centrifuged to remove water, washed and dried to obtain a spherical fine powder.

In the manner described above, spherical fine polymer powder can be easily obtained. Conditions that affect the particle size include the viscosity of the polymer solution, the stirring speed of the polymer solution, the method of adding water, and the amount of protective colloidal substances contained in the water.In general, the viscosity of the polymer solution Low, high stirring speed of polymer solution, little amount of added water at the beginning of the emulsification process,
When the amount of protective colloidal substance is large, the particle size tends to become smaller. In the present invention, the average particle diameter is 10
One with a diameter of 0 μm or less can be easily obtained, especially one with a diameter of 100 μm or less.
Particles smaller than μm can sufficiently function as fine powders in various applications.

In producing the thermoplastic spherical polymer fine powder of the present invention, an appropriate amount of an uncured thermosetting resin that is cured by external energy such as heat or light to form a three-dimensional cured product at least partially is dissolved in a polymer solution. By pulverizing the polymer into a spherical fine powder and then subjecting it to a curing treatment such as heating to form a cured product, a fine spherical polymer powder with improved heat resistance, chemical resistance, water absorption, strength, etc. can be obtained. As a thermosetting resin, an epoxy resin containing an epoxy curing agent, a maleimide resin, a resin having an acetylene end, a resin having a nadic acid end, a resin having a cyanate ester end,
Examples include resins having vinyl ends and resins having allyl ends.

In particular, epoxy resins containing epoxy curing agents are preferably used. The amount of thermosetting resin used is 1
The amount is preferably 150 parts by weight or less, and more preferably 50 parts by weight or less. If the thermosetting resin exceeds 150 parts by weight, the inherent properties of the thermoplastic polymer may deteriorate, which is not preferable.

When producing the spherical fine polymer powder of the present invention, pigments, dyes, antioxidants, lubricants, antistatic agents, plasticizers, and the like may be further dispersed and dissolved in the polymer solution. Also,
It is also possible to improve dispersibility and fluidity by adsorbing or sprinkling ultrafine powder such as silica or alumina on the surface of fine powder in an emulsion and/or dry state.

[Example] Examples are given below, but the present invention is not limited thereto.

Example 1 100 parts by weight of polysulfone (trade name: "Needel P-1700J, manufactured by Union Carbide") was mixed with 300 parts by weight of benzene.
The mixture was added to parts by weight and dissolved to obtain a polysulfone solution.

While stirring the solution at a rotational speed of 600 rpm at 45° C., 300 parts by weight of a 4% concentration polyvinyl alcohol (trade name [Gohsenol GL-054, manufactured by Nippon Gosei Kagaku Co., Ltd.)] was continuously added for 7 minutes. Added and initial W10
An O/W type emulsion was finally obtained from the type emulsion. The emulsion was heated to 70° C. while stirring at 40 rpm, and benzene was removed by volatilization under reduced pressure. Further, the emulsion was filtered and dehydrated, thoroughly washed with warm water, and then dried to obtain polysulfone particles having an average particle diameter of 11 μm. The particles were confirmed to be spherical by optical microscopic observation.

Example 2 Polyether sulfone (trade name "Pictrex 100")
100 parts by weight of "P" manufactured by ICI Corporation) were added to a mixed solvent of 294 parts by weight of methylene chloride and 6 parts by weight of methanol and dissolved to obtain a polyethersulfone solution. While stirring the solution at room temperature at a rotation speed of 700 rpm,
350 parts by weight of a 7% polyvinyl alcohol aqueous solution was continuously added over 10 minutes to obtain a final 0/W type emulsion from the initial W10 type emulsion. Next, add the emulsion to 30
The temperature was raised to 60° C. while stirring at 0 rpm, and methylene chloride and methanol were removed by volatilization.

Further, the emulsion was temporarily dehydrated, thoroughly washed with warm water, and then dried to obtain spherical polyethersulfone particles having an average particle diameter of 6.5 μm.

Example 3 Polyaryl sulfone (product name: "Sidel TMJ.

Spherical polyallylsulfone particles having an average particle diameter of 7 μm were obtained by carrying out the same operations as in Example 2, except that 100 parts by weight of Polyallyl Sulfone (manufactured by Union Carbide) and 300 parts by weight of chloroform were used.

Example 4 Polysulfone product name “Needel P-17004, UC”
>81.1 parts by weight manufactured by Company C, 15 parts by weight of epoxy resin (trade name "Epicote 828", manufactured by Yuka Shell Co., Ltd.) and 3.9 parts by weight of diaminodiphenylmethane as a hardening agent were added to 300 parts by weight of methylene chloride. Addition and dissolution yielded a viscous polymer solution.

Next, while stirring the solution at a rotational speed of 600 rpm at room temperature, 300% of a 4% polyvinyl alcohol aqueous solution was added.
Parts by weight were added continuously over a period of 10 minutes to finally obtain an O/W type emulsion from the initial W10 type emulsion. Subsequently, the temperature of the emulsion was raised to 45° C. while stirring at 300 rpm, and methylene chloride was removed by stirring. Further, the emulsion was heated to 85°C in an autoclave for 2.5 hours, and then for 15 hours.
The epoxy resin was cured by heat treatment at 0° C. for 2 hours. Finally, the emulsion was cooled to room temperature, filtered and dehydrated, thoroughly washed with warm water, and dried until the average particle size was 12 μm.
Polysulfone/cured epoxy resin composite spherical particles were obtained.

Example 5 Polyether sulfone (trade name [Pictrex 100
PJ, manufactured by ICI > 85.7 parts by weight, epoxy resin (trade name "Epicote 604J", manufactured by Yuka Shell Co., Ltd.) 1
0 parts by weight and 4.3 parts by weight of diaminodiphenylmethane as a curing agent were added and dissolved in a mixed solvent of 388 parts by weight of methylene chloride and 12 parts by weight of methanol to obtain a viscous polymer solution. While stirring the solution at a rotational speed of 60 rpm at room temperature, 400 parts by weight of a 5% polyvinyl alcohol aqueous solution was continuously added over 15 minutes to obtain the initial W1.
Finally, an O,/W type porous liquid was obtained from the type 0 emulsion. Next, the temperature of the emulsion was raised to 60°C while stirring at 300 rpm to volatilize and remove methylene chloride and methanol, and then the temperature was raised to 90'C and heat treatment was performed for 2 hours to partially remove the epoxy resin. hardened to. Next, the emulsion was heated to jFi
After washing thoroughly with warm water and drying, polyether sulfone/partially cured epoxy resin composite spherical particles were obtained. Finally, the particles were heated at 150°C for 2 hours and then at 180°C.
The epoxy resin was completely cured by heat treatment in hot air for 1 hour. The average particle diameter of the particles was 11 μm.

Example 6 Amorphous nylon (trade name rGRILAMID-TR55
J, manufactured by EMSERWERKE) was added to a mixed solvent of 300 parts by weight of chloroform and 100 parts by weight of ethanol and dissolved to obtain an amorphous nylon solution. While stirring the solution at room temperature at a rotational speed of 700 rpm, 300 parts by weight of a 4% polyvinyl alcohol aqueous solution was continuously added over 5 minutes to transform the initial WIO emulsion into a final O/W emulsion. Get the liquid. The dispersion was heated at 500 r
The temperature was raised to 70°C while stirring at pm to volatilize chloroform and ethanol. The emulsion was temporarily dehydrated, thoroughly washed with water, and then dried to obtain amorphous nylon spherical particles having an average particle diameter of 15 μm.

Example 7 100 parts by weight of the same amorphous nylon as in Example 6 was added to a mixed solvent of 400 parts by weight of methylene chloride and 200 parts by weight of methanol and dissolved to obtain an amorphous nylon solution. While stirring the solution at room temperature and a rotational speed of 550 rpm, 500 ml of a 2% aqueous polyvinyl alcohol solution was added.
Parts by weight were added continuously over a period of 10 minutes to finally obtain an O/W type emulsion from the initial W10 type emulsion. 4 of the emulsion
The temperature was raised to 60° C. while stirring at 0 rpm to volatilize methylene chloride and methanol. Next, the emulsion was filtered and dehydrated, thoroughly washed with water, and then dried to obtain amorphous nylon spherical particles with an average particle diameter of 24 μm.

Example 8 100 parts by weight of the same amorphous nylon as in Example 6 was added to a mixed solvent of 360 parts by weight of chloroform and 40 parts by weight of methanol and dissolved to obtain an amorphous nylon solution. While stirring the solution at room temperature at a rotation speed of 600 rpm,
400 parts by weight of a 6% polyvinyl alcohol solution (water/methanol = 6/4 (weight ratio)) was continuously added over 5 minutes to convert the initial W10 type emulsion to the final O/W.
Get a mold emulsion. The emulsion was heated to 60° C. while stirring at 400 rpm to volatilize chloroform and methanol. Next, the emulsion is filtered and dehydrated, thoroughly washed with water, and then dried to obtain amorphous nylon spherical particles having an average particle size of 6 μm.

Example 9 In Example 6, 80 parts by weight of amorphous nylon and epoxy resin (trade name "Epicote 828", Yuka Shell ■
) and 4 parts by weight of diaminodiphenylmethane.
．． Everything was the same as in Example 6, except that the amount was 2 parts by weight, and the emulsion from which the solvent had been volatilized was put into an autoclave and heat-cured at 90°C for 2 hours and then at 140°C for 2 hours. After performing the operation, the average particle size was 14μ.
Amorphous nylon spherical particles blended with m cured epoxy resin were obtained.

Example 10 Amorphous polyarylate (trade name “U Polymer (U-10
0) J, manufactured by Unitika Co., Ltd.) was added to 270 parts by weight of chloroform and dissolved to obtain a viscous amorphous polyarylate solution.

While stirring the solution at a rotational speed of 60 rpm at room temperature, 300 parts by weight of a 4% polyvinyl alcohol aqueous solution was continuously added over 10 minutes to transform the initial W10 type emulsion into a final O/W type emulsion. I got it. Subsequently, the emulsion was heated to 60° C. while stirring at 300 rpm to volatilize and remove chloroform. Next, the emulsion was temporarily dehydrated, thoroughly washed with warm water, and then dried until the average particle size was 11 μm.
m amorphous polyarylate spherical particles were obtained.

Example 11 80 parts by weight of the same amorphous polyarylate as in Example 10,
15 parts by weight of an epoxy resin (trade name "Epicote 828", manufactured by Yuka Shell Co., Ltd.) and 3.9 parts by weight of diaminodiphenylmethane as a hardening agent were added to 250 parts by weight of methylene chloride, and dissolved to form a viscous polymer. A solution was obtained.The solution was stirred at room temperature at a rotation speed of 600 rpm.
% concentration of polyvinyl alcohol aqueous solution to 1 part by weight
Continuously add for 0 minutes to obtain the final O/W type emulsion from the initial W10 type emulsion. Next, add the emulsion to 300%
The temperature was raised to 40° C. while stirring at rpm to volatilize and remove methylene chloride. Subsequently, the temperature of the emulsion was raised to 85°C in an autoclave equipped with a stirrer, and heat treatment was performed for 2 hours and then at 150°C for 3 hours with slow stirring to harden the epoxy resin. Finally, after cooling to room temperature, it is filtered and dehydrated, thoroughly washed with warm water, and dried until the average particle size is 8.
Amorphous polyarylate spherical particles blended with μm of cured epoxy resin were obtained.

Comparative Example 1 The same weight of polysulfone as in Example 1 was added to 15% of benzene.
0 parts by weight and dissolved to obtain a polysulfone solution.

The above polysulfone solution was gradually added to 600 parts by weight of a polyvinyl alcohol aqueous solution prepared in advance at a concentration of 4% while vigorously stirring at 800 rpm, and emulsification was performed as an O/W type emulsion.
A good emulsion was not obtained and was creamy. Furthermore, when benzene was volatilized, no particles were obtained, and most of the particles were in the form of lumps.

[Effects of the Invention] The present invention can provide a method for producing fine spherical thermoplastic polymer powder in a short time, efficiently, and at low cost, which has been difficult with conventional techniques.

Claims (5)

[Claims] (1) A method for producing fine spherical polymer powder, characterized by comprising the following steps (a) to (d). (a) A thermoplastic polymer is dissolved in an organic solvent to obtain a polymer solution. (b) Water containing an emulsifier is added to the polymer solution under stirring to emulsify the polymer solution through a water-in-oil (W/O) emulsion to an oil-in-water (O/W) emulsion. . (c) While stirring the emulsion, the organic solvent contained in the emulsion is evaporated. (d) Take out spherical polymer fine powder from the emulsion. (2) The method for producing a fine spherical polymer powder according to claim (1), wherein the organic solvent has a boiling point of less than 100°C and is substantially hardly soluble or insoluble in water. (3) The method for producing a fine spherical polymer powder according to claim (1), wherein the emulsifier is a protective colloidal substance. (4) The thermoplastic polymer is an aromatic polysulfone resin,
The spherical fine polymer powder according to claim (1), characterized in that it is selected from amorphous nylon and amorphous polyarylate. (5) The method for producing spherical fine polymer powder according to claim (1), wherein the polymer solution contains a thermosetting resin.