JPH06136220A - Tetrafluoroethylene resin composition - Google Patents

Abstract

PURPOSE:To provide a PTFE composition with excellent abrasion resistance and simultaneously prevent a soft metal such as aluminum from being damaged even when used as a sliding opposite material. CONSTITUTION:This tetrafluoroethylene resin composition is obtained by adding 1-50vol.% stannous oxide (SnO) or stannic oxide (SnO2) to 50-99vol.% tetrafluoroethylene resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tetrafluoroethylene resin composition as a material for sliding parts of various devices.

[0002]

2. Description of the Related Art Generally, tetrafluoroethylene resin (hereinafter referred to as
(This is abbreviated as PTFE) not only has excellent heat resistance and chemical resistance, but also has a small coefficient of friction and self-lubricating properties. Therefore, materials for sliding parts such as bearings and gears, pipes, valves, etc. It has been widely used in various fields as a representative of so-called engineering plastics such as molded products of.

However, this one is not always satisfactory in wear resistance and has a large deformation (creep) under load,
Limited use under high loads or high temperatures.

[0004] In order to improve such a defect of abrasion resistance of PTFE, it has been attempted to add various fillers. As the filler used in that case, for example, glass fiber powder, glass beads and carbon are used. Examples include inorganic fillers such as fibers, graphite and molybdenum disulfide, and organic fillers such as aromatic polyesters, polyimides, polyphenylene sulfides and aromatic polyamides.

[0005]

However, even the PTFE composition containing the above-mentioned various fillers cannot sufficiently improve the wear resistance, and in particular, the mating material which slides on the PTFE is soft. In the case of metal aluminum, the aluminum is damaged and abrasion powder is generated immediately after the start of sliding, and this aluminum powder attacks PTFE, so that there is a problem that abrasion is significantly promoted.

Therefore, the present invention solves the above-mentioned problems and makes the PTFE composition excellent in abrasion resistance, and particularly when a soft metal such as aluminum is used as a sliding mating material. The challenge is not to damage it.

[0007]

In order to solve the above problems, the present invention employs a means for producing a tetrafluoroethylene resin composition obtained by adding tin oxide to a tetrafluoroethylene resin. The details will be described below.

First, PTFE according to the present invention has a molecular weight of 300 containing tetrafluoroethylene as a repeating unit.
Since it is a polymer of 10 to 10 million and has a high melt viscosity at a melting point of 327 ° C. or higher, compression molding is possible at the time of molding, but ordinary injection molding is impossible.
Commercially available PTFE is manufactured by Italy Montedison Co., Ltd .: Algoflon, DuPont Co .: Teflon, UK IC
Fluoron manufactured by Ai Co., Ltd. and Polyflon manufactured by Daikin Industries, Ltd.

The tin oxide used in the present invention may be either stannous oxide (SnO) or stannic oxide (SnO ₂ ). These are usually in the form of powder, and various appearances can be obtained by the production method, but they can be used without particularly limiting such a shape. The particle size in the case of powder is 0.1 to 200.
The range of μm is preferable, and more preferably 0.5 to 100.
μm. This is because it is not suitable in terms of technology and cost for obtaining a powder having a particle size of less than 0.1 μm, and a large diameter exceeding 200 μm is not preferable because the friction and wear characteristics are not stable.

The amount of tin oxide added to PTFE is 1 to 50% by volume with respect to 50 to 99% by volume of PTFE.
Is preferred. Because, in a small amount of less than 1% by volume, the effect of addition is not recognized in the friction and wear characteristics, and 5
This is because if the amount exceeds 0% by volume, the moldability is significantly impaired, which is not preferable.

Various fillers may be added to such a PTFE composition as long as the effects of the present invention are not impaired. As the filler used in that case, for example, polyamideimide resin, polyetherimide resin, polyarylene sulfide resin, aromatic polyether ketone resin, polyarylene ether sulfone resin, phenolic resin, aromatic polyester resin, polyimide resin, silicone Including heat-resistant polymer materials such as resin and molten fluorocarbon resin, graphite fiber, wollastonite, potassium titanate fiber, heat-resistant inorganic single fiber such as calcium sulfate fiber, composite fiber such as magnesium sulfate fiber, and aroma Heat-resistant organic fibers such as group amide fibers, inorganic powders for improving lubricity such as molybdenum disulfide, graphite, carbon, mica, talc, molybdenum trioxide, iron oxide, cadmium sulfide, cadmium selenide, carbon black, etc. Inorganic face Mention may be made of a number of things, such as.

When these raw materials are mixed and molded, PT containing a filler, which has been widely used in the past, is used.
The molding may be performed under known FE molding conditions. As such a method, for example, dry mixing is performed with a mixer such as a tumbler mixer and a Henschel mixer, and the mixture is put into a mold, preformed by applying a pressure of 380 to 600 kg / cm ² , and then taken out from the mold. 3 compression molded products
A method of sintering at 70 ° C., a method of compression-molding batchwise while applying heat or a pressure, or a continuous molding method using a ram extruder can be adopted.

[0013]

The stannous oxide (SnO) or stannic oxide (SnO ₂ ) which is tin oxide added in the present invention
Improves the abrasion resistance of PTFE and protects the mating material by forming a strong transition film on the surface of the mating sliding material such as soft metal.

[0014]

EXAMPLES The raw materials used in Examples and Comparative Examples are collectively shown below. The abbreviations or chemical symbols are shown in [], and the mixing ratios are all volume%.

(1) Tetrafluoroethylene resin [PTFE] Teflon 7J manufactured by Mitsui DuPont Fluorochemicals (2) Stannous oxide [SnO] Wako Pure Chemicals: Reagent (3) Stannous oxide [SnO] ₂ ] Wako Pure Chemical Industries, Ltd .: Reagent (4) Lithium phosphate [Li ₃ PO ₄ ] Wako Pure Chemical Industries, Ltd .: Reagent (5) Copper oxide [CuO] Wako Pure Chemical Industries, Ltd .: Reagent (6) Lead oxide [PbO ] Mitsui Metal Industry Co., Ltd .: Lithage Y (7) Zinc Oxide [ZnO] Matsushita Electric Industrial Co., Ltd .: Panatetra (8) Calcium Carbonate [CaCO ₃ ] Nihon Kogyo Co., Ltd .: NA600 (9) Aromatic Polyester Resin [OP] Sumitomo Chemical Co., Ltd .: Econol E101M The above raw materials were blended in the proportions shown in Table 1 and dry-blended, and then put into a mold and preformed at a pressure of 500 kg / cm ² , and the compression molded product was obtained. 37 It was fired at ℃. From this molded body, a test piece having a predetermined shape and dimensions used for the following test method or was prepared, and the physical property values were measured. The results are also shown in Table 1.

Friction coefficient and wear coefficient Using a pin-on disk type friction and wear tester, sliding speed 8.3 m / min, load 700 gf, disk type mating material: aluminum alloy A5056 (surface roughness 3.2S), no lubrication The friction coefficient of the pin type test piece (diameter 8 mm, radius of curvature of pin tip: R50) under the condition of
And 120 minutes later. Further, the wear coefficient (cm ³ / kgf · m) was calculated from the weight change and the specific gravity of the material after the test machine was operated for 120 minutes and before the operation.

After the test of the damage degree of the mating material, the surface roughness shape of the sliding surface was measured, and it was evaluated in two stages of no damage (marked with ◯) and damage (marked with x).

[0018]

[Table 1]

As is clear from the test results in Table 1, in Examples 1 and 2, the mating material was not damaged at all, the friction coefficient and the wear coefficient before and after the test were stable and low, and the wear resistance was excellent. It showed excellent physical properties.

On the other hand, among Comparative Examples in which compounds other than tin oxide were added and blended, Comparative Examples 1, 2 and 4 to 6
Indicates damage to the mating material, and Comparative Example 3 is inferior in friction coefficient and wear coefficient, and none of them satisfies both desired wear resistance and mating material damage resistance.

[0021]

[Effect] As described above, the present invention is a tetrafluoroethylene resin composition in which tin oxide is added to a tetrafluoroethylene resin. It has excellent properties, and has the advantage that even if a soft metal such as aluminum is used as a sliding partner material, it will not be damaged. In particular, it can be said that it is optimal as a material for sliding parts such as bearings.

Claims (1)

[Claims] 1. A tetrafluoroethylene resin composition obtained by adding tin oxide to a tetrafluoroethylene resin.