JP2003327708A - Method for manufacturing polytetrafluoroethylene- containing mixed powder, and thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polytetrafluoroethylene- containing mixed powder which has no discoloration even if stored for a long period of time and has a capability of producing a molded article with good quality when added to a thermoplastic resin. <P>SOLUTION: The method for manufacturing the polytetrafluoroethylene- containing mixed powder which contains polytetrafluoroethylene (A) and an organic polymer (B) comprises a process of preparing the organic polymer (B) by emulsion polymerization using as an emulsifier at least one compound selected from the group consisting of dipotassium alkenylsuccinate, sodium 1,4-dicyclohexylsulfonate, sodium dioctylsulfosuccinate and sodium laurate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a mixed powder containing polytetrafluoroethylene and a thermoplastic resin composition.

[0002]

2. Description of the Related Art Polytetrafluoroethylene (PTF)
E) has excellent heat resistance, chemical resistance, electrical insulation, water- and oil-repellency, non-adhesiveness, self-swelling property, and the like,
Widely used in coating agents. In addition, since it has high crystallinity and low intermolecular force, it has the property of forming fibers with slight stress. When compounded with a thermoplastic resin, molding processability, mechanical properties, etc. are improved. It is also used as an additive. However, polytetrafluoroethylene is poor in dispersibility in general thermoplastic resins containing no halogen atom. Therefore, in JP-A No. 11-29679, a polytetrafluoroethylene-containing mixed powder composed of polytetrafluoroethylene particles having a particle diameter of 10 μm or less and organic polymer particles is used to provide polytetrafluoroethylene for a thermoplastic resin. Described that the thermoplastic resin with improved dispersibility of fluoroethylene and the addition of polytetrafluoroethylene-containing mixed powder has good processability and mechanical properties, and also has excellent appearance. Has been done.

[0003]

However, the polytetrafluoroethylene-containing mixed powder produced by the method described in JP-A No. 11-29679 has a discolored powder color when stored for a long period of half a year or more. Will end up. Also,
In the process of producing polytetrafluoroethylene-containing mixed powder (during solidification), the powder adhering to high-temperature parts such as steam pipes gradually discolors, which becomes a problem during powder recovery. there were. Further, when the recovered powder is added to the thermoplastic resin, there is a defect that the molded product is burnt and colored. An object of the present invention is to provide a method for producing a polytetrafluoroethylene-containing mixed powder capable of producing a molded product of high quality when added to a thermoplastic resin without discoloration even after long-term storage. .

[0004]

Means for Solving the Problems As a result of intensive studies in view of the above circumstances, the present inventors have found that by using a specific emulsifier when preparing an organic polymer by emulsion polymerization,
No discoloration due to long-term storage or heating, resulting in
The present inventors have found that a molded product having an excellent appearance can be obtained when added to a thermoplastic resin without generating lumps during powder recovery, and thus arrived at the present invention.

That is, a method for producing a polytetrafluoroethylene-containing mixed powder containing the polytetrafluoroethylene (A) and the organic polymer (B) of the present invention is a dipotassium alkenyl succinate and a 1,4-dicyclohexyl sulfone. Sodium acid salt, sodium dioctyl sulfosuccinate,
The method is characterized by having a step of preparing the organic polymer (B) by emulsion polymerization using at least one selected from the group consisting of sodium laurate as an emulsifier. Further, the above-mentioned method for producing a polytetrafluoroethylene-containing mixed powder comprises a step of coagulating or spray-drying a mixed dispersion liquid containing polytetrafluoroethylene (A) and an organic polymer (B). It is preferable to have. The thermoplastic resin composition of the present invention is characterized by containing the polytetrafluoroethylene-containing mixed powder produced by the above production method.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a method for producing a polytetrafluoroethylene-containing mixed powder which is preferably used as an additive for a thermoplastic resin. The structure of the mixed powder containing polytetrafluoroethylene will be described below.

The polytetrafluoroethylene (A), which is a constituent component of the polytetrafluoroethylene-containing mixed powder, is preferably not an agglomerate having a particle size of more than 10 μm, more preferably a particle size of 0. .0
It is 5 to 1.0 μm. If only polytetrafluoroethylene (A) aggregates to form an aggregate of 10 μm or more, it is not preferable from the viewpoint of dispersibility in the thermoplastic resin.
In addition, as the polytetrafluoroethylene (A), a commercially available product may be used, or a product obtained by polymerizing a tetrafluoroethylene monomer may be used.

As commercially available polytetrafluoroethylene (A), Fluoron AD-1 (Asahi Glass Co., Ltd.)
), Fluon AD-936 (manufactured by Asahi Glass Co., Ltd.), Polyflon D-1 (manufactured by Daikin Industries, Ltd.), Polyflon D
-2 (manufactured by Daikin Industries, Ltd.), Teflon (registered trademark)
30J (manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.), Fluon AD936 (manufactured by Asahi Glass Fluoropolymers Co., Ltd.)
Etc. can be mentioned. By dispersing these in water containing an emulsifier and the like, it is possible to obtain a dispersion liquid of polytetrafluoroethylene (A) having a particle size in the above-mentioned predetermined range.

As the polytetrafluoroethylene (A) obtained by polymerizing a tetrafluoroethylene monomer, for example, one obtained by emulsion polymerization using a fluorine-containing surfactant can be used. In addition, fluorine-containing olefins such as hexafluoropropylene, chlorotrifluoroethylene, fluoroalkylethylene, and perfluoroalkyl vinyl ether, and perfluoroalkyl (meth), as long as the characteristics of polytetrafluoroethylene (A) are not impaired.
Polytetrafluoroethylene copolymerized with a fluorine-containing alkyl (meth) acrylate such as acrylate can also be used. However, the content of the copolymerization component is preferably 10% by mass or less.

Monomers of the organic polymer (B), which is a constituent of the polytetrafluoroethylene-containing mixed powder, include styrene, p-methylstyrene, o-methylstyrene, p-chlorostyrene and o-chloro. Styrene-based monomers such as styrene, p-methoxystyrene, o-methoxystyrene, 2,4-dimethylstyrene, α-methylstyrene; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate. , Butyl methacrylate, 2-ethylhexyl acrylate,
(Meth) acrylate monomers such as 2-ethylhexyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate. A vinyl cyanide monomer such as acrylonitrile or methacrylonitrile; vinyl methyl ether,
Vinyl ether type monomers such as vinyl ethyl ether; Vinyl carboxylate type monomers such as vinyl acetate and vinyl butyrate;
Examples thereof include olefin-based monomers such as ethylene, propylene and isobutylene; diene-based monomers such as butadiene, isoprene and dimethylbutadiene.
They may be used alone or in combination of two or more.

Further, when the polytetrafluoroethylene-containing mixed powder is added to the thermoplastic resin, the monomer constituting the organic polymer (B) should be appropriately selected according to the thermoplastic resin used. Is preferred. For example, when the thermoplastic resin is polymethylmethacrylate, from the viewpoint of compatibility, the (meth) acrylic acid ester-based monomer is 20% by mass.
It is preferable to use the organic polymer (B) contained above. Further, when the thermoplastic resin is polyester, it is preferable to use an organic polymer (B) containing a styrene-based monomer and a (meth) acrylic acid ester-based monomer, particularly preferably from the viewpoint of compatibility. Is an organic polymer (B) containing 1 mass% or more of a (meth) acrylic acid ester-based monomer having an epoxy group.

The particle diameter d of the organic polymer (B) is not particularly limited, but from the viewpoint of stability of the aggregated state with the polytetrafluoroethylene (A),
The range of the following formula (I) is preferable with respect to the particle diameter D of the polytetrafluoroethylene (A). 0.1D <d <10D (I)

In the present invention, as an emulsifying agent, at least one selected from the group consisting of dipotassium alkenyl succinate, sodium 1,4-dicyclohexyl sulfonate, sodium dioctyl sulfosuccinate, and sodium laurate is used to form an organic system by emulsion polymerization. A polymer (B) is prepared. As described above, the polytetrafluoroethylene-containing mixed powder containing the organic polymer (B) prepared by using the specific emulsifier as a constituent does not discolor by long-term storage or heating, and As an additive of a thermoplastic resin, it is possible to exert particularly excellent effects on molding processability and mechanical properties.

The polytetrafluoroethylene-containing mixed powder will be described in detail later. For example, a mixed dispersion obtained by mixing a dispersion liquid of polytetrafluoroethylene (A) and a dispersion liquid of an organic polymer (B). It is obtained by coagulating or spray-drying the liquid into powder. The polytetrafluoroethylene-containing mixed powder produced in this manner is agglomerated particles in which the polytetrafluoroethylene (A) and the organic polymer (B) are agglomerated due to the difference in surface charge, and each is agglomerated without aggregation. It contains polytetrafluoroethylene (A) which is present alone and an organic polymer (B).

The agglomerated particles have a structure in which polytetrafluoroethylene (A) and the organic polymer (B) are integrated, and the morphology thereof depends on the mixing ratio of both particles and the particle size. There can be many things. That is, the polytetrafluoroethylene (A) is surrounded by the organic polymer (B), and conversely, the organic polymer (B) is surrounded by the polytetrafluoroethylene (A).
There is a form surrounded by, a form in which several particles are aggregated for one particle, and the like. The content of polytetrafluoroethylene (A) in the polytetrafluoroethylene-containing mixed powder is 0.1% by mass to 90% by mass.
Is preferred.

An example of the method for producing the polytetrafluoroethylene-containing mixed powder of the present invention will be described below. For example, first, a monomer constituting the organic polymer (B) is charged into a reaction vessel, and further, dipotassium alkenyl succinate, sodium 1,4-dicyclohexylsulfonate,
A dispersion liquid of the organic polymer (B) is prepared by adding at least one emulsifier selected from the group consisting of sodium dioctyl sulfosuccinate and sodium laurate and emulsion-polymerizing it. Here, the amount of the emulsifier used is not limited, but is preferably about 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the monomer constituting the organic polymer (B). If it is less than 0.1 part by mass, the amount of emulsifier may be insufficient and a large amount of cullet may be generated during polymerization. If it exceeds 5.0 parts by mass, foaming during polymerization and coagulation tends to be severe. is there. On the other hand, a tetrafluoroethylene monomer is emulsion-polymerized in a separate reaction vessel using a fluorinated surfactant to prepare a dispersion liquid of polytetrafluoroethylene (A). The dispersion of polytetrafluoroethylene (A) thus prepared and the dispersion of the organic polymer (B) are mixed to prepare a mixed dispersion, which is then powdered by a method such as coagulation or spray drying. Turn into.

When the mixed dispersion is pulverized by spray drying, for example, the mixed dispersion may be sprayed in a vacuum container to evaporate the water to recover the polytetrafluoroethylene-containing mixed powder. it can.

As a method for producing a polytetrafluoroethylene-containing mixed powder other than the above, in a mixed dispersion liquid in which a dispersion liquid of polytetrafluoroethylene (A) and a dispersion liquid of an organic polymer (B) are mixed. Also, it can be obtained by emulsion-polymerizing a monomer having an ethylenically unsaturated bond and pulverizing it by coagulation or spray drying.

As the ethylenically unsaturated monomer, styrene, p-methylstyrene, o-methylstyrene, p-chlorostyrene, o-chlorostyrene, o-chlorostyrene, etc. may be used depending on the use of the polytetrafluoroethylene-containing mixed powder. Styrene-based monomers such as p-methoxystyrene, o-methoxystyrene, 2,4-dimethylstyrene, α-methylstyrene; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, methacryl. Butyl acid, 2-ethylhexyl acrylate,
Acrylic ester monomers such as 2-ethylhexyl methacrylate, dodecyl acrylate, dodecyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; vinyl methyl ether , Vinyl ether type monomers such as vinyl ethyl ether; vinyl carboxylate type monomers such as vinyl acetate and vinyl butyrate; olefin monomers such as ethylene, propylene and isobutylene; dienes such as butadiene, isoprene, prene and dimethyl butadiene It can be selected from among the system monomers. These monomers can be used alone or in combination of two or more.

As described above, according to the present invention, the polytetrafluoroethylene-containing mixture which does not discolor during powder recovery, has excellent dispersibility in the thermoplastic resin, and does not discolor even when stored for a long period of time. A powder can be obtained.

The thermoplastic resin composition containing the polytetrafluoroethylene-containing mixed powder produced as described above and a thermoplastic resin will be described below.

As the thermoplastic resin, polyolefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate (PE
T), polyethylene naphthalate, polycyclohexane terephthalate, polybutylene terephthalate (PB
T), polyester resin such as polybutylene naphthalate, polycarbonate (PC), butadiene rubber graft copolymer (for example, ABS resin), acrylic rubber graft copolymer, silicone-acrylic composite rubber graft copolymer, ethylene propylene rubber Graft copolymer,
Styrene resin such as HIPS, AS, vinyl chloride resin,
Polyacetal resin, polyphenylene sulfide resin, polyphenylene ether resin (PPE), polyamide resin such as nylon 6 and nylon 66 (PA), PMM
Acrylic resin such as A, PET / PBT, PC / PBT,
PBT / ABS, PC / ABS, PA / ABS, PPE
Although / PBT, PPE / HIPS, PPE / PA, etc. are mentioned, a polyolefin resin is preferable and a polypropylene resin is more preferable.

Examples of the polyolefin resin include polypropylene, polyethylene, poly-1-butene, polyisobutylene, a random or block copolymer of propylene and ethylene and / or 1-butene in an arbitrary ratio, and ethylene and propylene. Ethylene-propylene-with an arbitrary ratio and a diene component of 50% by mass or less
Monomers other than olefins having an ethylenically unsaturated bond, such as diene terpolymer, polymethylpentene, ethylene or propylene and 50 mass% or less of vinyl acetate, (meth) acrylic acid alkyl ester, and aromatic vinyl compound. And a random, block or graft copolymer with

Specific examples of preferable polyolefins include a propylene-based polyolefin containing 50% by mass or more of propylene as a monomer, and 100 parts by mass of a propylene-based polyolefin containing 50% by mass or more of propylene as a monomer. 50% by mass of ethylene as body
Ethylene-based polyolefin containing 0.1 to 100
Mixtures with parts by weight, especially ASTM D123
When the melt flow rate according to No. 8 is 10 g / 10 minutes or less, the melt tension is high and the workability is excellent, which is preferable. The melt flow rate of polypropylene is measured at 230 ° C. under a load of 2.16 kg, and that of polyethylene is measured at 190 ° C. under a load of 2.16 kg according to ASTM D1238.

The blending amount of the polytetrafluoroethylene-containing mixed powder is 0.001 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin. In that case, the blending amount of polytetrafluoroethylene (A) is 0.0001 to 100 parts by mass of the thermoplastic resin.
It is preferably in the range of 40 parts by mass.

The thermoplastic resin composition obtained by adding the polytetrafluoroethylene-containing mixed powder to the thermoplastic resin has an increased tension during melting during its processing, and has a removability during calendering and a thermoformability during thermoforming. Alternatively, the drawdown of the molten resin during blow molding, the open cell formation of cells during foam molding, and the like are improved, and the workability such as calendering, thermoforming, blow molding, and foam molding is improved. Further, the discharge amount at the time of extrusion molding and the surface condition of extrusion molded products such as sheets and films are improved, and extrusion processability is improved.

Further, the thermoplastic resin composition of the present invention comprises
Fillers can be added if desired. As the filler, calcium carbonate, talc, glass fiber, carbon fiber, magnesium carbonate, mica, kaolin, calcium sulfate, barium sulfate, titanium white, white carbon, carbon black, ammonium hydroxide, magnesium hydroxide, aluminum hydroxide, etc. Is mentioned.
Among these, calcium carbonate and talc are preferable.

The blending amount of the above-mentioned filler is the thermoplastic resin 10
It is preferably 0.1 to 400 parts by mass, more preferably 1 to 350 parts by mass, and further preferably 1 to 300 parts by mass, relative to 0 parts by mass. Rigidity and heat resistance are improved by the blending of this filler, and workability such as prevention of sticking to the roll surface in calendering is improved.
Cost reduction can be achieved. If the blending amount of the filler is less than 0.1 parts by mass, the effect of improving the rigidity is not sufficient, and if it is more than 400 parts by mass, the surface property tends to deteriorate.

If desired, additives such as stabilizers, lubricants, flame retardants and the like can be added to the thermoplastic resin composition of the present invention. As a stabilizer, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-]
Hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] and other phenolic stabilizers, tris (monononylphenyl) phosphite, tris ( Examples thereof include phosphorus-based stabilizers such as 2,4-di-t-butylphenyl) phosphite and sulfur-based stabilizers such as dilaurylthiodipropionate.

Examples of the lubricant include sodium, calcium or magnesium salts of lauric acid, palmitic acid, oleic acid or stearic acid.

Examples of the flame retardant include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl phenyl phosphate, octyl diphenyl phosphate, diisopropylphenyl phosphate, Tris. Phosphoric ester compounds such as (chloroethyl) phosphate, alkoxy-substituted bisphenol A bisphosphate, hydroquinone bisphosphate, resorcin bisphosphate, polyphosphates such as trioxybenzene triphosphate, tetrabromobisphenol A, decabromodiphenyl oxide, hexabromocyclododecane , Octabromodiphenyl ether, bistri Lomophenoxyethane, ethylene bistetrabromophtylimide, tribromophenol, various halogenated epoxy oligomers obtained by reaction of halogenated bisphenol A with epihalohydrin, carbonate oligomer having halogenated bisphenol A as a constituent, halogenated polystyrene, Examples thereof include halogen-containing compounds such as chlorinated polyolefins and polyvinyl chloride, metal hydroxides, metal oxides, sulfamic acid compounds and the like.

The thermoplastic resin composition of the present invention contains a thermoplastic resin and a polytetrafluoroethylene-containing mixed powder, and is obtained by mixing a filler and other additives, if necessary. . As a mixing method, conventionally well-known methods such as extrusion kneading and roll kneading are used. It is also possible to carry out multi-stage mixing such that a part of the thermoplastic resin is mixed with the polytetrafluoroethylene-containing mixed powder to prepare a masterbatch, and then the remaining thermoplastic resin is further added and mixed.

The processing method of the thermoplastic resin composition is as follows:
Examples include calender molding, extrusion molding, thermoforming, blow molding, injection molding, foam molding and melt spinning. Further, useful molded articles obtained by using the thermoplastic resin composition of the present invention include a sheet, a film, a thermoformed body, a hollow molded body, an injection molded body, a foamed molded body,
A fiber etc. can be mentioned.

As explained above, according to the thermoplastic resin composition of the present invention, the polytetrafluoroethylene (A)
Because of excellent dispersibility, it is possible to obtain a molded product excellent in workability, rigidity, surface appearance and the like.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In each Example and Comparative Example, "part" means "part by mass",
"%" Indicates "mass%".

Example 1 Dodecyl Methacrylate 60
Part, 35 parts of methyl methacrylate, and 5 parts of methyl acrylate were added to a mixed solution of cumene hydroxyperoxide.
3 parts were dissolved. As an emulsifier for this, dipotassium alkenyl succinate (“Latemur ASK”, Kao Corporation)
(Manufactured) and added a mixed solution of 2.0 parts in terms of solid content and 300 parts of distilled water, and add 5 parts at 10,000 rpm with a homomixer.
After stirring for 1 minute, the homogenizer was passed twice at a pressure of 20 MPa to obtain a stable preliminary dispersion liquid. This is a stirrer,
A flask equipped with a condenser, a thermocouple, a nitrogen inlet, and a reagent dropping device was charged and heated to 60 ° C. in a water bath under a nitrogen stream. 0.0004 parts of ferrous sulfate, 0.0012 parts of disodium ethylenediaminetetraacetate, and 0.2 parts of L-(+)-ascorbic acid were dissolved in 5 parts of distilled water and added to start polymerization, and the mixture was kept for 3 hours. A dispersion of the organic polymer (B) was obtained. The solid content concentration of the dispersion liquid of the organic polymer (B) is 25.
At 1%, the particle size distribution showed a single peak and the mass average particle size was 170 nm. Also, 83.3 parts of Fluon AD936 (manufactured by Asahi Glass Fluoropolymers Co., Ltd.)
116.7 parts of distilled water was added to (containing 63.0% of solid content and 5% of polyoxyethylene alkylphenyl ether with respect to polytetrafluoroethylene) to give polytetraxane having a solid content of 26.2%. A dispersion liquid of fluoroethylene (A) was obtained. The dispersion liquid of polytetrafluoroethylene (A) is 25% polytetrafluoroethylene and 1.2%.
% Polyoxyethylene alkyl phenyl ether. In addition, polytetrafluoroethylene (A) in the dispersion liquid of polytetrafluoroethylene (A)
Had a particle diameter of 0.3 μm. 120 parts of the dispersion of polytetrafluoroethylene (A) (30 parts of polytetrafluoroethylene) and 199.2 parts of the dispersion of organic polymer (B) (50 parts of dodecyl methacrylate / methyl methacrylate copolymer) And into a separable flask equipped with a stirring blade, condenser, thermocouple, and nitrogen inlet,
The mixture was stirred under a nitrogen stream for 1 hour. Then, the temperature of the system was raised to 80 ° C., and the mixture was stirred for 1 hour, and then iron (II) sulfate 0.001
Parts, disodium ethylenediaminetetraacetate 0.003
Parts, L-(+)-ascorbic acid 0.1 parts, distilled water 6
Add 0.8 parts of the mixture and add 1 part of methyl methacrylate.
A mixed solution of 9 parts, 1 part of methyl acrylate and 0.4 part of cumene hydroxyperoxide was added dropwise over 1 hour, and after completion of the addition, the internal temperature was kept at 80 ° C. for 1 hour to complete radical polymerization. Separation of solids was not observed through a series of operations, and a uniform mixed dispersion was obtained. This mixed dispersion was poured into 400 parts of hot water at 90 ° C. containing 3 parts of aluminum sulfate,
The solid matter was separated, filtered and dried to obtain 98 parts of polytetrafluoroethylene-containing mixed powder.

(Example 2) As an emulsifier, sodium 1,4-dicyclohexylsulfonate ("Perex C") was used.
S ", manufactured by Kao Corporation, was used in the same manner as in Example 1, except that polytetrafluoroethylene-containing mixed powder 99 was used.
I got a part. The solid content concentration of the organic polymer (B) dispersion was 25.0%, the particle size distribution showed a single peak, and the mass average particle size was 220 nm.

Example 3 A polytetrafluoroethylene-containing mixed powder 100 was prepared in the same manner as in Example 1 except that sodium dioctylsulfosuccinate (“Perex OTP”, manufactured by Kao Corporation) was used as an emulsifier. I got a part. The solid content concentration of the organic polymer (B) dispersion was 25.1%, the particle size distribution showed a single peak, and the mass average particle size was 215 nm.

(Example 4) As an emulsifier, sodium lauryl sulfate ("Emar 2F-30", manufactured by Kao Corporation)
100 parts of polytetrafluoroethylene-containing mixed powder were obtained in the same manner as in Example 1 except that was used. The solid content concentration of the organic polymer (B) dispersion was 25.1%.
The particle size distribution showed a single peak, and the mass average particle size was 230 nm.

Comparative Example 1 Sodium dodecylbenzene sulfonate (“NEOPEREX F-2” was used as an emulsifier.
5 ", manufactured by Kao Corporation, was used in the same manner as in Example 1, except that polytetrafluoroethylene-containing mixed powder 99 was used.
I got a part. The solid content concentration of the organic polymer (B) dispersion was 24.9%, the particle size distribution showed a single peak, and the mass average particle size was 170 nm.

Comparative Example 2 Example 1 was repeated except that sodium alkyldiphenyl ether disulfonate (“Perex SS-L”, manufactured by Kao Corporation) was used as an emulsifier.
In the same manner as above, 99 parts of a mixed powder containing polytetrafluoroethylene was obtained. The solid content concentration of the organic polymer (B) dispersion was 25.1%, the particle size distribution showed a single peak, and the mass average particle size was 225 nm.

<Evaluation Test (1)> The polytetrafluoroethylene-containing mixed powders obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were stored at room temperature (23 ° C.) for 6 months. As the evaluation criteria, those in which discoloration was visually observed were evaluated as ◯, and those in which discoloration was not observed were evaluated as x. The results are shown in Table 1.

<Evaluation Test (2)> The polytetrafluoroethylene-containing mixed powder obtained in Examples 1 to 4 and Comparative Examples 1 and 2 was shaped by a press molding machine (120 ° C., 3.0 MPa). It was heated in a gear oven at 220 ° C. for 1 hour. The evaluation standard was that the degree of coloring was visually observed, no coloring was observed at all, and the appearance was good, and
Coloring was recognized and the appearance was very inferior, and it was evaluated as 5 and evaluated in 5 levels. The results are shown in Table 1.

[0044]

[Table 1]

As is clear from the results shown in Table 1, Example 1
The polytetrafluoroethylene-containing mixed powders obtained in Nos. 4 to 4 do not discolor even after being stored for 6 months, and no coloring is observed even when heated, so that a lump occurs during powder recovery. Without using it as an additive of a thermoplastic resin, there is no need to worry about the conventional problems such as burning and coloring of the molded product. On the other hand, the polytetrafluoroethylene-containing mixed powders obtained in Comparative Examples 1 and 2 show discoloration when stored for 6 months, and coloring is observed when heated, and therefore, as an additive of the thermoplastic resin, It turned out to be inferior.

[0046]

EFFECTS OF THE INVENTION According to the method for producing a mixed powder containing polytetrafluoroethylene of the present invention, there is no discoloration due to long-term storage or heating, and the dispersibility in a thermoplastic resin is excellent. A mixed powder can be obtained. Further, according to the thermoplastic resin composition of the present invention, a molded product having excellent processability, rigidity, surface appearance, etc. can be obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Osuka             20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayo             Otake Office F-term (reference) 4F070 AA12 AA13 AA15 AA18 AA24                       AA25 AA28 AA29 AA32 AA34                       AA40 AE14 AE28 CB01 DA32                       DA34 FA05                 4J002 AC03X AC06X BB03X BB03Y                       BB05Y BB12X BB12Y BB15Y                       BB16X BC03X BC03Y BC08X                       BC09X BD05Y BD15W BF02X                       BG04X BG05X BG06Y BG10X                       BN00Y BP02Y BP03Y BQ00X                       CB00Y CF03Y CF05Y CF08Y                       CG01Y CH07Y CL01Y CL03Y                       CN03Y                 4J011 AA05 KA01

Claims (3)

[Claims] 1. A method for producing a polytetrafluoroethylene-containing mixed powder containing polytetrafluoroethylene (A) and an organic polymer (B), comprising: dipotassium alkenyl succinate and 1,4-dicyclohexyl sulfonic acid. Polytetrafluoroethylene characterized by having a step of preparing an organic polymer (B) by emulsion polymerization using at least one selected from the group consisting of sodium, sodium dioctylsulfosuccinate and sodium laurate as an emulsifier. A method for producing a mixed powder containing. 2. The method according to claim 1, further comprising a step of coagulating a mixed dispersion liquid containing the polytetrafluoroethylene (A) and the organic polymer (B) or pulverizing it by spray drying. 6. A method for producing a polytetrafluoroethylene-containing mixed powder according to claim 1. 3. A thermoplastic resin composition comprising the polytetrafluoroethylene-containing mixed powder produced by the production method according to claim 1.