JPH0655835B2 - Method for manufacturing thermoplastic resin molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Use> The present invention relates to a method for producing a thermoplastic resin molded product in which tetrafluoropolyethylene is dispersed. More specifically, it relates to a method for producing a thermoplastic resin molded product in which tetrafluoropolyethylene having a fibril forming ability is uniformly dispersed.

<Prior Art> It has been conventionally known to mix a tetrafluoropolyethylene powder with a thermoplastic resin in order to impart abrasion resistance to the thermoplastic resin. As the polyethylene tetrafluoride powder to be mixed with the plastic resin, there has been used one which has been previously fired so as to lose its ability to form fibrils and to be hard to aggregate.

On the other hand, the present inventor tried to mix tetrafluoroethylene with a flame retardant in order to suppress combustion dripping in a polycarbonate resin combustion test. However, the use of a commonly used tetrafluoropolyethylene that has been pre-calcined to lose its cohesiveness does not provide the effect of suppressing combustion drips, whereas tetrafluoride having fibril-forming ability is used. We have found that polyethylene has the desired effect.

However, when the tetrafluoride polyethylene powder having the ability to form fibrils is mixed by the dry blending method which is usually performed, the tetrafluoride polyethylene powder is immediately aggregated due to the friction between the powders generated during the mixing, and The surface of the molded product obtained by molding is extremely rough, and the commercial value is poor.

Further, in order to add the tetrafluoropolyethylene powder to fluororubber, silicone polymer, NBR, butyl rubber, polyimide resin, etc., the tetrafluoropolyethylene powder is made into a dispersion liquid, which is 10 ° C or less, specifically 5 ° C. There is known a method in which the dispersion liquid or the solution of the above resin is cooled and then added (JP-A-63-101430). However, in order to cool the dispersion liquid of polyethylene tetrafluoride to 5 ° C. as described above, a special device is required, which causes complicated work and an increase in cost, which is not a preferable method.

<Object of the Invention> An object of the present invention is to provide a polycarbonate resin molded product which does not require a special device and uniformly contains tetrafluoropolyethylene having fibril forming ability.

The present inventor has made earnest studies for achieving the above object, and when a polycarbonate resin is extrusion-molded, if a dispersion liquid of polyethylene tetrafluoride is continuously supplied and mixed and dispersed in an extruder, the polyethylene tetrafluoride is obtained. It has been found that the dispersion liquid can be mixed with extremely good dispersibility without being particularly cooled. As a result of further studies based on this finding, the present invention has been completed.

<Structure of the Invention> That is, in the present invention, when a thermoplastic resin molded product in which tetrafluoropolyethylene having a fibril forming ability is dispersed is manufactured using an extruder, the tetrafluoropolyethylene is used as a dispersion liquid. A method for producing a thermoplastic resin molded article is characterized in that the thermoplastic resin molded article is continuously supplied without being mixed with a thermoplastic resin and mixed and dispersed in an extruder.

The tetrafluoropolyethylene used in the present invention has a fibril forming ability, and the dispersion medium for forming the dispersion liquid may be any as long as it does not substantially adversely affect the thermoplastic resin to be added. Water can be used, and water is preferably used when the thermoplastic resin is polycarbonate. The concentration of the dispersion liquid may be such that the dispersion state is stable, but if it is too thin, problems due to the dispersion medium may occur, so 5% by weight or more is preferable, and a range of 5-60% by weight is particularly preferable.

The thermoplastic resin targeted by the present invention is not particularly limited as long as it is an extrudable thermoplastic resin, and examples thereof include polyvinyl chloride, polyethylene, polypropylene, polymethylmethacrylate, polystyrene, acrylonitrile-styrene polymer, acrylonitrile-butadiene-styrene polymer. General-purpose resins such as polycarbonate, 4-methylpentene-1, polyamide, polyester, polyphenylene ether, polymethylene ether, and other general-purpose engineering resins, and other thermoplastic resins, and polycarbonate is particularly preferable. The polycarbonate is preferably an aromatic polycarbonate produced by a solvent method or a melting method using a divalent aromatic phenol.

In the present invention, when the thermoplastic resin is extruded into pellets by using an extruder, the pellets are extruded while supplying the dispersion liquid of tetrafluoropolyethylene. The extruder used here does not have to be a special extruder and may be a single-screw or twin-screw extruder, but a twin-screw extruder is preferable from the viewpoint of biting property and kneading property. Further, in consideration of removal of the dispersion medium, removal of volatile components, etc., a vent is preferable. Both open and reduced pressure are adopted.

The supply of the above dispersion liquid is quantitatively dropped, flowed or pressed into the hopper portion of the extruder, especially the bottom portion thereof, and the vent, particularly the first vent portion when a plurality of vents are provided in the extruder. As the constant quantity feeder, for example, a plunger pump, a gear pump, a tube pump, a press-fitting pump, an electromagnetic constant quantity pump, a diaphragm pump, a magnet pump and the like can be arbitrarily used.

The supply amount can take a wide range depending on the purpose.

In order to suppress combustion dripping of polycarbonate, when mixing the above tetrafluoride polyethylene with a flame retardant,
It is about 0.1 to 5% by weight, and even in this case, up to about 20% by weight may be added when forming a master pellet.

In carrying out the present invention, additives such as pigments, dyes, UV stabilizers, heat stabilizers, mold release agents, flame retardants, and other fillers can be mixed if necessary. Even when such additives or fillers are used, the dispersion liquid of tetrafluoropolyethylene having a fibril forming ability is supplied without being mixed with the additives or fillers in advance and mixed in the extruder.

<Effects of the Invention> According to the present invention, it is possible to provide a thermoplastic resin molded product that does not require a special device and uniformly contains tetrafluoropolyethylene having fibril forming ability, and according to the present invention. Once a pellet is molded and a molded product is produced using this, a thermoplastic resin molded product containing, in particular, tetrafluoropolyethylene having fibril-forming ability uniformly dispersed by any molding method, particularly a molded product having an excellent appearance. Can be provided.

<Examples> The present invention will be described in detail below with reference to Examples. Appearance of molded product 90mm
Injection molding a sample plate of 50 mm x 2 mm x 100 mm, and judging by a 100x micrograph, flame retardancy was injection molded with 5 test pieces of 1.27 mm x 12.7 mm x 1.59 mm and evaluated according to UL-94. did.

Example 1 5000 parts by weight of a polycarbonate powder having a viscosity average degree of polymerization of 22000 was mixed with 10 parts by weight of carbon black, and the mixture was dried at 130 ° C. for 5 hours with a table feeder at a supply rate of 5 kg / hour, while fibril forming ability was obtained. Aqueous dispersion (Polyflon D-1 manufactured by Daikin Co., Ltd.) containing 60% by weight of polyethylene tetrafluoride having a
It was continuously fed separately to the hopper of a twin-screw extruder with a vent at a feed rate of 5 g / hour, and pelletized by vent opening at 270 ° C. The resulting pellets are then placed in a 3 ounce injection molding machine
A sample plate was molded at 340 ° C and a mold temperature of 80 ° C. 1 side of sample board
The surface was extremely smooth and judged to be satisfactory with light selection, as judged by a micrograph taken at 00 times.

Example 2 Pellets were prepared in the same manner as in Example 1 except that 250 parts by weight of a carbonate oligomer of tetrabromobisphenol A was further mixed with the polycarbonate powder mixed with the carbon black of Example 1, pellets were prepared, and a flame retardant plate was prepared. Five test pieces were prepared. When the surface of the sample plate was judged by a 100 times micrograph, the surface was extremely smooth and satisfactory with light selection, and the flame retardancy was V-0.

Comparative Example 1 Polycarbonate powder mixed with carbon black of Example 1 was further mixed with 15 parts by weight of tetrafluoride polyethylene powder (Teflon 6J manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.) having a capability of forming fibrilyl, to obtain tetrafluoroethylene polyethylene. Pellets were prepared and sample plates were prepared in the same manner as in Example 1 except that the supply of the dispersion liquid was stopped. 100 on the surface of the sample board
Judging from a doubled photomicrograph, it is obvious that the surface has large irregularities, the gloss is poor, and the fluorinated polyethylene powder is poorly dispersed.

Claims (1)

[Claims] 1. A process for producing a thermoplastic resin molded product in which tetrafluoropolyethylene capable of forming fibrils is dispersed by using an extruder, wherein the tetrafluoropolyethylene is used as a dispersion liquid, which is a thermoplastic resin. A method for producing a thermoplastic resin molded article, characterized in that the thermoplastic resin molded article is continuously fed without being mixed with the mixture and mixed and dispersed in an extruder.