JPS60199045A - Fluororesin composition - Google Patents

Abstract

PURPOSE:To obtain a composition of significantly improved moldability while retaining the excellent characteristics inherent in fluororesin, also causing no corrosion of the molding machine, by kneading, under a molten state, a fluororesin of specific particle size and polyolefin resin. CONSTITUTION:The objective composition can be obtained by kneading, under a molten state, (A) 90-60wt% of a fluororesin of an average particle size 2-20mu and (B) 10-40wt% of a polyolefin resin, alternatively, another composition comprising (1) 85-50wt% of said fluororesin, (2) 5-10wt% of graphite or molybdenum disulfide, (3) 10-40wt% of said polyolefin resin will have higher resistance to wear. Said fluororesin should be polytetrafluoroethylene, whereas the polyolefin resin either polyethylene or polypropylene one.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fluororesin compositions. More specifically, the present invention relates to a fluororesin composition prepared by mixing a fluororesin with an average particle size of 2 to 20 μm with a polyolefin resin, or mixing the fluororesin with a polyolefin resin and graphite or molybdenum disulfide, and melting and intermixing the mixture.

Fluororesin (especially volite)'y fluoroethylene (hereinafter P
It's called TFB. ) has various characteristics such as heat resistance, chemical resistance, electrical insulation, low coefficient of friction, low abrasion, and non-adhesion, so its application fields are chemical, mechanical, electrical and electronic industrial fields. It has spread widely to the field of household goods.

However, the melting point is 327°C and the melt viscosity is 10"-1
Since it has an extremely high 0t* void and does not flow even if it exceeds its melting point, melt processing and molding methods applied to general plastics cannot be applied. Therefore, a special molding method such as compression molding or ram extrusion molding is required. In order to improve such moldability, fluororesins with lowered melting points and melt viscosity, such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA), tetrafluoroethylene-hexafluoropropylene copolymers (FBP), Polychlorotrifluoroethylene (
Several types of fluororesins, including PCTFE) and f-fluoroethylene-ethylene copolymer (ETFE), have been developed as heat-melting type fluororesins and are commercially available. However, even though many heat-melting type fluororesins have been developed that can be molded in the same way as general thermoplastic resins, FTFB, which is said to have moldability problems, has excellent heat resistance, chemical resistance, and electrical insulation. Due to its properties such as flexibility, non-adhesiveness, and low coefficient of friction, 70% of total fluoropolymer resins are shipped.
are used in greater amounts.

In addition, even heat-melting type fluororesin, which has a lower melting point and melt viscosity and is said to be able to be extruded and injection molded in the same way as general thermoplastic resins, has problems with molding machine corrosion, and injection molding Its melt fluidity is inferior to general polyolefin resins, such as the need to make sprues, runners, and gates thicker and shorter, making it difficult to mold in exactly the same way as polyolefin resins.

The present inventor has conducted extensive research in order to improve these problems with fluororesins. As a result, by adding 10 to 40% by weight of polyolefin resin to fluororesin, especially FTFB, various properties as fluororesin (excellent heat resistance, chemical resistance, electrical insulation, low coefficient of friction, low abrasion) can be improved. The present invention has been completed based on the discovery that it is possible to obtain a fluororesin that has the same properties as polyolefin resins, has exactly the same moldability as polyolefin resins, and is free from corrosion problems.

As is clear from the above description, an object of the present invention is to provide a fluororesin composition that can be molded to the same level as polyolefin resins and is free from corrosion problems, while maintaining the various properties of fluororesins.

The present invention has the following configuration.

(1) A fluororesin composition obtained by mixing 90 to 60% by weight of a fluororesin with an average particle size of 2 to 20 μm and 10 to 40% by weight of a polyolefin resin, and then melting and cross-mixing the mixture.

(2) A fluororesin composition prepared by mixing and melting 85-50% by weight of a fluororesin having an average particle size of 2-20μ, 5-10% by weight of graphite or molybdenum disulfide, and 10-40% by weight of a polyolefin resin.

As the fluororesin used in the present invention, PTFB having a particle size of 2 to 20 μm is preferable because it is excellent in various properties such as heat resistance, electrical insulation, low coefficient of friction, and low abrasion. Particularly preferred is PTPE having a particle size of 2 to 10 microns.

When the particle size is less than 2 μm, secondary aggregation tends to occur during mixing with the polyolefin resin, resulting in poor dispersibility. Also, if the particle size exceeds 20μ, polyolefin resin and UPT
Although the apparent dispersion improves when mixed with F B resin,
This is not preferable because the dispersion of the polyolefin resin phase and the FTFB resin phase in the material used to form the molded product becomes worse, and sufficient performance is not exhibited.

In addition, as polyolefin resins, ethylene,
, homopolymers of α-olefins such as butene, random copolymers of the α-olefins and other α-olefins, block copolymers, and mixtures of two or more of these are used. The amount of polyolefin resin added is 10 to 40% by weight.
A range of is preferred. A particularly preferable range is 10 to 30% by weight. If the amount is less than 10% by weight, good moldability cannot be obtained, and molding similar to that of polyolefin resins becomes difficult. Moreover, if it exceeds 40% by weight, various properties of the fluororesin, particularly properties such as wear resistance and low coefficient of friction, deteriorate, which is not preferable.

Furthermore, if the amount of polyolefin resin added exceeds 50% by weight, the various properties of the fluororesin, especially its wear resistance and low friction coefficient, deteriorate by an order of magnitude or more, making it no longer suitable for use as a fluororesin. Live with hardship. This point is different from the composition according to the present invention and a polyolefin resin composition containing 50 or less fluororesin.

Furthermore, in order to further improve the mechanical properties, particularly the wear resistance, of the composition, 5 to 10% by weight of graphite or molybdenum disulfide may be added as necessary. 5% by weight
When added without grooves, the improvement effect is not significant, and when added in an amount exceeding 10% by weight, the moldability is greatly reduced in spite of the improvement in the effect, which is not preferable.

Further, in the present invention, additives which are usually added to polyolefins, such as antioxidants, antistatic agents, metal salts of higher fatty acids, pigments, inorganic fillers, glass fibers, etc., can be used in combination.

This composition contains a predetermined amount of fluororesin, polyolefin resin,
It is obtained by mixing molybdenum disulfide or the like as required, and melting and kneading the mixture in a twin-screw extruder.

As a mixing device, a mixing device such as a Hensel mixer (trade name), a mixer with a high-speed stirrer such as a super mixer, a Panpari mixer, a ribbon grinder, etc. may be used. A normal twin-screw extruder is used for melt mixing. The melt crosstalk temperature is 200°C to 300°C, preferably 220°C to 28°C.
It is 0°C.

Various test pieces were prepared from the pellets of the fluororesin composition thus obtained, and their moldability using an injection molding machine was examined. Naturally, a molded article of 100% by weight fluororesin could not be obtained under normal injection molding conditions. In contrast, it was confirmed that the fluororesin composition of the present invention could be molded under exactly the same molding conditions as ordinary polyolefin resins, and test pieces could be molded. Mechanical properties such as abrasion resistance and dynamic and static friction coefficients were measured using these test pieces. Measurement of abrasion resistance is based on JIS K
7204 (C817 wheels, 1 kg load, 23℃
, 1000 rotations), and the dynamic and static friction coefficients were measured using A8.
TMT) 1894 (length: 65 m, width: 65 mm, thickness: 2+111 flat plate, sharpening-resistant steel).

In addition, as a comparative product, since it was impossible to mold fluororesin, a commercially available product was obtained and a comparative test was conducted.

As a result, the fluororesin composition of the present invention satisfies low abrasion and low friction coefficient, which are one of the characteristics of fluororesins, and can be molded using the same molding method as ordinary polyolefin resins. It was confirmed that

PTFI! At room temperature, the resin has mechanical strength (tensile strength) similar to that of so-called engineering/engineering resins, but it only exhibits mechanical strength roughly equivalent to that of polyolefin resins, but at low or high temperatures. It exhibits extremely superior mechanical strength compared to general plastics.

Although the composition according to the present invention has a much higher tensile strength at high temperatures than general plastics, although its mechanical strength (tensile strength) at high temperatures is slightly inferior to that of the FTFB resin itself, it has sufficient tensile strength at high temperatures. The composition of the present invention is suitable for use as a sliding material that takes advantage of its good moldability and low abrasion and friction properties, as well as automobile parts, electrical appliance parts, and other general industrial applications. It can be used in the field of parts.

The present invention will be concretely illustrated in the following examples and comparative examples.O Example 1, comparative example 1 70% by weight of polytetrafluoroethylene having a particle size of 5μ and a polyolefin resin have a melt flow rate of 8.0 r 710 minutes (temperature 230 Load at °C 2.16
Discharge amount of WI melt resin for 10 minutes when adding kg)
Polypropylene homopolymer or melt flow rate of 4. (1710 min propylene ethylene copolymer 30
% by weight in a Hensel mixer, and
Melt-knead and pelletize using a shaft extruder at a melt mixing temperature of 250°C.90 These pellets are put into an ordinary injection molding machine for polyolefins, and the injection pressure is 40 to 14 okgt/crlG (4
! ! The moldability was observed under the following molding conditions: injection speed 4011 I/sec, resin temperature 250°C, mold temperature 50°C, and a flat plate with length Zoom, width 10011% and thickness 21111 was molded. did.

Furthermore, as Control Example 1, a commercially available molded product of polytetrafluoroethylene was used.

Using the above test pieces, abrasion properties, dynamic and static friction coefficients were measured.

Example 2 70% by weight of polytetrafluoroethylene with a particle size of 5μ and a polyolefin resin with a melt index of s, or/lo min (load of 2.15 at a temperature of 190°C)
A polyethylene homopolymer (30 weight) of molten resin (discharge amount of molten resin in 10 minutes when adding kg) was pelletized in the same manner as in Example 1, injection molded in the same manner and under the same conditions as in Example 1, Formability was observed, and abrasion properties, dynamic and static friction coefficients were measured.

Example 3, Control Example 2 70% by weight of polytetrafluoroethylene having a particle size of 5μ and polypropylene homopolymer with a melt flow rate of 8.0 f/10 min as a polyolefin resin or propylene with a melt flow rate of 4.0 f/10 min 20% by weight of ethylene copolymer and 10% by weight of graphite
After mixing with a Hensel mixer, the moldability, abrasion properties, and dynamic and static friction coefficients were measured in the same manner as in Example 1.

As Control Example 2, a commercially available molded product of polytetrafluoroethylene containing graphite was used.

Example 4, Control Example 3 A polypropylene homopolymer with a melt 70-rate of 8.0 f/1G as a polyolefin resin and 70% by weight of polytetrafluoroethylene having a particle size of 5μ, or a melt 70-rate of 4, Ot/ After mixing 20% by weight of propylene ethylene copolymer and 10% by weight of molybdenum disulfide in a Hensel mixer, Example 1
Its formability, abrasion resistance, and dynamic and static friction coefficients were measured using the same method as above.

Further, as a control example 3, a commercially available molded product of polytetrafluoroethylene containing molybdenum disulfide was used.

These results are summarized in Table 1.

Table 1 As can be seen from Table 1, the fluororesin composition according to the present invention can be molded in exactly the same manner and under the same conditions as ordinary polyolefins, and yet maintains the excellent performance of fluororesins. This was confirmed.

The composition according to the present invention has good moldability, and is widely used in fields such as sliding materials that take advantage of its low abrasion and low friction properties, as well as various automobile parts, electrical appliance parts, and general industrial parts. It turned out that it can be used.

Amendment of the above procedure Written in April 1983 2tH L Matter of FFO Indication 1982 Patent Application @ 54953 & Title of invention Fluororesin composition & Relationship to the case making the amendment q # Applicant Osaka, Osaka Prefecture 3-6-32 Nakanoshima, Ichikita-ku (530)
(20)) Chisso Co., Ltd. Representative Sadao Nogi Principal Agent 2-8-1 Shinjuku, Shinjuku-ku, Tokyo (160)a No number of inventions will increase as a result of the amendment. "Explanation" column a Correction oP3e Correct "Ribbon Grender" in the first line of page 8 of the specification to "Ribbons Lender."

that's all

Claims (4)

[Claims] (1) A fluororesin composition prepared by mixing 90 to 60% by weight of a fluororesin with an average particle size of 2 to 20 μm and 10 to 40% by weight of a polyolefin resin, and then melting and cross-mixing the mixture. (2) A fluororesin composition prepared by mixing 85 to 50 weight of a fluororesin with an average particle size of 2 to 20 μm, 5 to 10 weight of graphite or molybdenum disulfide, and 10 to 40 weight of a polyolefin resin, and melting and cross-mixing them. (3) The composition according to claim 1, wherein the fluororesin having an average particle size of 2 to 20 μm is polytetrafluoroethylene, and the polyolefin resin is polyethylene resin or polypropylene resin. (4) The composition according to claim 2, wherein the fluororesin having an average particle size of 2 to 20 μm is polytetrafluoroethylene, and the polyolefin resin is polyethylene resin or polypropylene/resin.