JP2003026883A - Abrasion-resistant fluororesin composition and member for sliding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluororesin composition exhibiting excellent abrasion resistance under sliding with an another resin having a rough surface and a member for sliding composed of the composition. SOLUTION: This composition is composed of a first fluororesin unexposed to radiation, a second fluororesin exposed to radiation at 1-10 kGy under <=100 Torr of oxygen pressure and a filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear-resistant fluororesin composition and a sliding member, and more particularly to a fluororesin composition exhibiting excellent wear resistance under sliding with an opponent having a rough surface, and The present invention relates to a sliding member composed of a composition.

[0002]

2. Description of the Related Art Fluorine resins are widely used as packings, gaskets, insulating materials, containers for semiconductor production, etc. because of their excellent surface lubricity, heat resistance, chemical resistance, electrical characteristics and the like. However, since the fluororesin is inferior in wear resistance and creep resistance, it is difficult to apply it to applications where it is used in a sliding environment or a high temperature compression environment.

As a countermeasure for improving these characteristics, there is known a method of cross-linking the molecules by irradiating a fluorine resin with radiation, and this method is, for example, fluorine for a sliding member or the like. It is used as an effective means to enable the application of resins.

[0004]

However, according to the conventional sliding member based on the irradiated fluorine resin, when the surface roughness of the other party of sliding becomes larger than a certain level, the wear resistance sharply decreases. Therefore, there is a problem that the application range is restricted.

Accordingly, it is an object of the present invention to provide a fluororesin composition which exhibits excellent wear resistance under sliding with a counterpart having a rough surface, and a sliding member composed of this composition. .

[0006]

In order to achieve the above object, the present invention provides a first fluororesin which is not irradiated with radiation and an oxygen concentration of 1 to 10 under an oxygen concentration of 100 torr or less.
A wear-resistant fluororesin composition comprising a second fluororesin irradiated with MGy radiation and a filler.

Further, in order to achieve the above object, the present invention provides a sliding member composed of a molded body that slides with a contacting partner, wherein the molded body is not irradiated with radiation. A sliding member comprising a mixture of a first fluororesin, a second fluororesin irradiated with radiation of 1 to 10 MGy under an oxygen concentration of 100 torr or less, and a filler. It is provided.

Examples of the above-mentioned first fluororesin include tetrafluoroethylene polymer (hereinafter referred to as PTFE), tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (hereinafter referred to as PFA), or tetrafluoroethylene- A hexafluoropropylene-based copolymer (hereinafter referred to as FEP) or the like is used.

Further, for example, PTFE obtained by copolymerizing 1 mol% or less of a polymer unit such as perfluoro (alkyl vinyl ether), hexafluoropropylene, (perfluoroalkyl) ethylene or chlorotrifluoroethylene, further, It is also possible to use a polymer or copolymer obtained by copolymerizing a small amount of the third component, and it is particularly preferable to use PTFE.

The specific examples listed above are the same in the case of the second fluororesin, and the same polymer or copolymer is applied. It is particularly preferable to use carbon fiber as the filler, and other suitable fillers include glass fiber, metal fiber and the like.

In the present invention, the reason why the oxygen concentration at the time of irradiating the second fluororesin with radiation is limited to 100 torr or less is that when the oxygen concentration exceeds this, oxidative deterioration of the material occurs and good wear resistance is obtained. The reason why the irradiation dose of radiation is limited to 1 to 10 MGy is that when the irradiation dose is less than 1 kGy, a sufficient effect of improving wear resistance cannot be obtained. This is because if it exceeds 10 MGy, the elongation and the like are significantly reduced. A more preferable oxygen concentration can be set to 10 torr or less, and in that case, it is preferable that the atmosphere is an inert gas atmosphere.

In many cases, ionizing radiation such as electron beam, γ ray, X ray, neutron ray or high energy ion is used as the radiation applied to the second fluororesin. The irradiation is preferably carried out by heating above the crystalline melting point of the fluororesin.
327 ℃ or higher for TFE and 310 ℃ for PFA
As described above, in the case of FEP, heating to 275 ° C. or higher is a preferable condition.

The heating at the time of irradiation as described above acts to activate the molecular motion of the main chain constituting the fluororesin, so that efficient crosslinking work can be performed.
However, since excessive heating causes breakage and decomposition of the molecular main chain, its temperature should be set within a range 10 to 30 ° C. higher than the crystal melting point.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the wear resistant fluororesin composition and the sliding member according to the present invention will be described.

[Example 1] A molding powder of PTFE (G-163, manufactured by Asahi Glass Co., Ltd.) was heated to 380 ° C for 30 times in the air.
After firing by heating for 1 minute, oxygen concentration 0.1
Irradiation with an electron beam at a dose of 100 kGy in a vacuum of torr and under heating at 340 ° C.,
By pulverizing this with a jet mill, a modified PTFE powder as a second fluororesin having an average particle diameter of 20 μm was obtained.

Next, 10 parts by weight of this modified PTFE powder,
Non-irradiated PTFE powder (TFM-170 manufactured by Mitsui DuPont Co., Ltd.) as the first fluororesin which has not been irradiated.
0) 85 parts by weight, and carbon fiber (Kureha Chemical Co.,
(M-201S) 5 parts by weight are mixed with a Hensyl mixer while being cooled to 20 ° C. or lower, and the obtained mixed powder is compression molded at room temperature and a pressure of 50 MPa, and then the peak temperature is 350 ° C. and the conditions are 2 hours. A rod having a diameter of 40 mm and a length of 60 mm is formed by sintering below, and finally, the rod is sliced by a lathe to have a thickness of 0.5.
mm sheet was produced.

[0016]

Example 2 In Example 1, the modified PTFE powder was mixed in an amount of 10 parts by weight, and the unirradiated PTFE powder was mixed in an amount of 80 parts by weight.
A sheet having a thickness of 0.5 mm was manufactured by setting the weight part and the mixing amount of the carbon fiber to 10 parts by weight and setting the other conditions to the same conditions.

[0017]

[Example 3] In Example 1, the modified PTFE powder was mixed in an amount of 10 parts by weight and the unirradiated PTFE powder was mixed in an amount of 70 parts by weight.
A sheet having a thickness of 0.5 mm was manufactured by setting the weight part and the mixing amount of the carbon fibers to 20 parts by weight and setting the other conditions to the same conditions.

[0018]

Comparative Example 1 The unirradiated PTFE powder of Example 1 was heated to a temperature of 35.
Compression molding for 1 hour at 0 ° C. and a pressure of 50 MPa,
Subsequently, a rod having a diameter of 40 mm and a length of 60 mm was molded by cooling to room temperature while maintaining a pressure of 50 MPa, and then a rod having a thickness of 0.5 mm was manufactured by slicing the rod.

[0019]

Comparative Example 2 20 parts by weight of the modified PTFE powder of Example 1 and 80 parts by weight of unirradiated PTFE powder were mixed with a Hensyl mixer while cooling to 20 ° C. or lower, and the resulting mixed powder was heated at room temperature and a pressure of 50 MPa. After compression molding under the original
A rod having a diameter of 40 mm and a length of 60 mm was molded by sintering at a peak temperature of 350 ° C. for 2 hours, and finally, a rod having a thickness of 0.5 mm was manufactured by slicing the rod with a lathe. .

[0020]

Comparative Example 3 50 parts by weight of the modified PTFE powder of Example 1 and 50 parts by weight of unirradiated PTFE powder were mixed with a Hensyl mixer while cooling to 20 ° C. or lower, and the resulting mixed powder was heated at a temperature of 350 ° C. It is compression-molded under a pressure of 50 MPa for 1 hour, and subsequently cooled to room temperature while maintaining a pressure of 50 MPa, so that a diameter of 40 mm and a length of 6
A 0 mm rod was molded, and finally, this was sliced by a lathe to manufacture a sheet having a thickness of 0.5 mm.

Table 1 summarizes the compositional contents of the fluororesin compositions in the above Examples and Comparative Examples and the characteristic test results of the sheet samples obtained from them. The test contents of the main characteristics are as follows.

Specific wear amount: Using a thrust type friction wear tester, a cylindrical ring made of SUS304 (outer diameter 25.6 mm × inner diameter 20.6 m) according to JIS K 7218.
m) test piece (outer diameter 25.6 mm × inner diameter 20.6 mm ×
The amount of wear after 50 hours has elapsed when the test was carried out under the conditions of a pressure of 0.4 MPa and a speed of 125 mm / min after bonding (0.5 mm in thickness).

Creep: According to ASTM D621-64, the creep property when compressed at 200 ° C. is measured. -Permanent deformation: The deformation rate is shown when a pressure load of 7 MPa is continuously applied for 24 hours, the load is released, and 24 hours after the load is released. -Tensile test (elongation, tensile strength): According to JIS K 6891, a tensile speed of 200 mm / min.

[0024]

[Table 1]

According to Table 1, in comparison with Examples 1 to 3 where the specific wear amount remains at a low level, Comparative Example 1
In the cases of 1 and 2, a remarkably high specific wear amount is shown. This is because Comparative Example 1 does not include both the modified fluororesin and the carbon fiber, while Comparative Example 2 does not include the carbon fiber, and the difference between them is the specific wear amount. It appears as the difference between.

In the case of the test A, the specific wear amount of Comparative Example 3 is superior to that of Examples 1 to 3, but this is because the surface roughness of the sliding partner is fine.
In the case of the test B having a large roughness, the specific wear amount is remarkably higher than those of Examples 1 to 3. The good or bad wear resistance is clearly shown when sliding with a counterpart having a rough surface, and therefore, the excellent wear resistance provided in the example is particularly remarkable when compared with this comparative example 3. Become.

Table 1 clearly shows the specificity and usefulness of the abrasion-resistant fluororesin composition according to the present invention and the sliding member formed by using the composition, and the application of the fluororesin according to the present invention. It can be said that the effect of improving the sex is great.

[0028]

As described above, according to the present invention,
1st fluorine resin not irradiated with radiation, 100to
The composition is composed of the second fluororesin irradiated with 1 to 10 MGy of radiation under the oxygen concentration of rr or less, and the filler, so that it has excellent wear resistance in sliding with the counterpart with a rough surface. A fluororesin composition can be provided, and further, a highly wear-resistant sliding member using the same can be provided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuaki Yamamoto             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd. F term (reference) 4J002 BD15W BD15X BD16W BD16X                       BE04W BE04X DA016 FA046                       GM04 GM05

Claims (4)

[Claims] 1. A first fluororesin that has not been irradiated with radiation and 1 to 10 M under an oxygen concentration of 100 torr or less.
A wear-resistant fluororesin composition comprising a second fluororesin irradiated with Gy radiation and a filler. 2. The abrasion-resistant fluororesin composition according to claim 1, wherein the first and second fluororesins are tetrafluoroethylene-based polymers. 3. The wear-resistant fluororesin composition according to claim 1, wherein the filler is carbon fiber. 4. A sliding member formed of a molded body that slides with a contacting partner, wherein the molded body has a first fluororesin and an oxygen concentration of 1 to 100 torr or less. A sliding member comprising a mixture of a second fluororesin irradiated with 10 MGy of radiation and a filler.