JP2824075B2 - Molded body of composition for sliding part material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a molded product of a composition for a sliding portion material which is indispensable for a mechanical element.

[Conventional technology]

Polytetrafluoroethylene resin is widely used as a sealing material because of its excellent heat resistance, chemical resistance, sliding properties, etc. However, this resin alone causes a large amount of deformation due to external force and a large amount of wear. Therefore, attempts have been made to improve these disadvantages by blending various fillers. For example, glass fiber, carbon fiber, metal powder, etc. are used as fillers. However, in recent years, use under severe conditions has increased, and the conventional PV has a limit PV value (here, the PV value is It is used to express characteristics and is a reference for mutual comparison of bearing materials. It is expressed as a function of pressure P and sliding surface speed V. The higher this value, the better the pressure resistance and speed resistance. ), It is becoming impossible to respond to such demands. Aluminum is increasingly used as the mating material for the sliding part due to the recent tendency to reduce the weight. However, the conventional sliding part material wears the mating aluminum material. Had many difficulties.

[Problems to be solved by the invention]

As described above, in the prior art, the sliding PV has a high limit PV value, and hardly wears a soft mating material such as aluminum, and can sufficiently withstand the use conditions that have become particularly severe in recent years. There is a problem that a composition for a sliding portion material having characteristics has not been obtained, and it has been a problem to solve this problem.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention provides a carbon compound powder having an average fiber diameter of 1 to 20 μm and an aspect ratio of 1 to 50, 2 to 30% by weight, and a calcium compound powder having an average particle diameter of 0.5 to 40 μm. Means of containing 0.5 to 50% by weight as an essential component, with the balance being a molded body of a composition for a sliding portion material composed of a tetrafluoroethylene resin. The details are described below.

First, the tetrafluoroethylene resin of the present invention (hereinafter referred to as "the
(Abbreviated as PTFE) is a homopolymer of ethylene tetrafluoride, manufactured by Montegison Incorporated: Algoflon, manufactured by Dupont, USA: Teflon, manufactured by ICI, UK: Fluon, manufactured by Daikin Industries: It is a kind of fluororesin commercially available under the registered trade names such as polyflon, and is a resin which can be compression-molded but cannot be subjected to ordinary injection molding.

Next, the carbon fiber according to the present invention has an average fiber diameter of 1 to 20 μm, preferably 5 to 15 μm, and an aspect ratio of 1 to 50, preferably 5 to 30. This is because if the average fiber diameter is smaller than 1 μm, cohesion between the fibers occurs and uniform dispersion becomes difficult. If the average fiber diameter is larger than 20 μm, the soft mating material is worn. This is because the reinforcing effect is impaired and the mechanical properties are reduced. Conversely, if it exceeds 50, it is extremely difficult to uniformly disperse the mixture during mixing, which is unfavorable because it impairs the abrasion characteristics and leads to a reduction in quality. And
Such desirable carbon fibers include Torayca ML: Torayca ML
D-30, manufactured by Kureha Chemical Industry Co., Ltd .: Creca M201S and M2007S.

Further, the calcium compound in the present invention is calcium carbonate, sulfate, oxide, hydroxide,
Among them, calcium carbonate and calcium sulfate are preferred. The average particle size of these calcium compounds is 0.5 to 40 μm
The reason for preferably limiting the range to 1 to 30 μm is 0.5 μm.
This is because if the particles are smaller than m, agglomeration occurs between the particles, making uniform dispersion difficult, and if the particles are larger than 40 μm, the surface smoothness deteriorates, which is not preferable.

The mixing ratio of these essential components in the present invention is 2 to 20% by weight of carbon fiber, preferably 5 to 20% by weight,
The reason that the calcium compound is 0.5 to 50% by weight, preferably 2 to 35% by weight, and the balance is ethylene tetrafluoride resin is that when the carbon fiber is in a small amount less than the lower limit, an improvement in wear resistance can be almost expected. In addition, when the amount is larger than the upper limit, the soft counterpart material is worn.When the calcium compound is smaller than the lower limit, the soft counterpart material is similarly worn, and conversely, the large amount exceeds the upper limit. In such a case, the mechanical characteristics are deteriorated, which is not preferable.

The mixture blended in the above ratio may be molded under ordinary molding conditions for PTFE with a filler, which has been widely used in the past.For example, a tumbler mixer, a Henschel mixer, or another mixer may be used to mold PTFE, carbon fiber, and calcium compound. And dry-mix the three ingredients in a mold.
After preforming under a pressure of 380~600kg / cm ^2, a method of sintering at 370 ° C. The compression molded body taken out from the mold, the other heating and pressing while batch compression molding methods or ram extruder Any method such as continuous extrusion molding may be used. In addition, in the resin composition of the present invention, as in the case of the ordinary resin composition, solid lubricants such as carbon powder, silica stone, and molybdenum disulfide are used within a range that does not impair the main purpose of the present invention. Reinforcing agents such as glass fiber, boron fiber, silicon carbide fiber, asbestos, rock wool, and metal fiber; flame retardants such as antimony trioxide and magnesium carbonate; and electrical property modifiers such as clay, mica, asbestos, silica, and graphite; Acid resistance improvers such as barium sulfate and silica, glass beads, glass spheres, alumina,
A substance that is stable at a high temperature of about 380 ° C. or more, such as talc, diatomaceous earth, hydrated alumina, shirasu balloon, an extender such as a metal oxide, and a pigment, may be appropriately mixed. The proportion of the remaining ethylene tetrafluoride resin when adding such an additive is preferably not lower than 15% by weight.

〔Example〕

Raw materials used in Examples and Comparative Examples described below are collectively shown as follows. In addition, each abbreviation is entered in [], and the mixing ratio is% by weight.

Polytetrafluoroethylene resin [PTFE] (manufactured by Du Pont-Mitsui Fluorochemicals: Teflon 7J, powder), carbon fiber [CF-1] (manufactured by Toray Industries: Torayca MLD30, average fiber diameter 7 μm, aspect ratio 1 to 30), carbon Fiber [CF-2] (Kureha Chemical Co., Ltd .: Creca M201S, average fiber diameter 12.5μ)
m, aspect ratio 1 to 40), calcium carbonate [CaCO ₃ ] (Nisshi Kogyo Co., Ltd .: NA600, average particle size 7 μm), calcium sulfate [CaSO ₄ ] (Wako Pure Chemical Industries, Ltd .: reagent grade, average particle size) 1 μm), Examples 1 to 5: Each raw material was dry-blended at the ratio shown in Table 1 and placed in a mold, preformed under a pressure of 550 kg / cm ² , and then removed from the mold. The compression molded body was formed into a sintered molded body at 370 ° C. From this molded body, test pieces having dimensions and shapes specified in various test methods were produced. The various test methods are as follows.

(1) Tensile strength (kg / cm ² ) and elongation (%) According to ASTM-D638, (2) Coefficient of linear expansion (× 10 ^-5 / ° C) According to ASTM-D695, (3) Friction test Thrust type friction Sliding speed by test machine 150m / min, load
1.1kg / cm ² , mating material ADC-12 (T6 treatment), lubricating oil suniso 4G
Find the friction coefficient of S under forced lubrication conditions.

(4) Wear coefficient as ^{(× 10 -10 cm 3 / kg} · m) Low PV condition, slipping velocity per minute 96m by a thrust-type abrasion tester, a load 5 kg / cm ^2, the mating material ADC-12 (T6 treatment)
Select the forced lubrication conditions for the lubricating oil Suniso 4GS and find its wear coefficient. As the high PV condition, a sliding speed of 128 m per minute by a thrust type abrasion tester, a load of 10 kg / cm ² , and other conditions same as those of the low PV condition are selected, and the wear coefficient at that time is obtained.

Table 1 also shows the results obtained by the above tests.

Comparative Examples 1 to 4: Specimens were prepared in exactly the same manner as in Examples 1 to 5, except that the mixing ratio of each raw material was as shown in Table 2, and various tests were performed. The results obtained are shown in Table 2.

The following is clear from Tables 1 and 2.
That is, each of the molded articles obtained in Examples 1 to 5 comprising the composition for a sliding portion material of the present invention exhibits balanced mechanical properties, and exhibits sliding properties under a high PV condition with respect to a soft counterpart material. The dynamic characteristics are also very good and the balance on both sides is very good. On the other hand, Comparative Example 2 in which the amount of carbon fiber added was out of the limited range of the present invention was particularly high.
In the PV condition, the wear coefficient was large, and in Comparative Example 4, the mating material had large wear, the friction coefficient was high, and the tensile elongation, one of the mechanical properties, was significantly reduced. In addition, the molded article in Comparative Example 1 in which the amount of the calcium compound added was out of the range of limitation of the present invention had large wear on the mating material, and the molded article in Comparative Example 3 was also particularly high.
Under the PV conditions, the abrasion was large, the coefficient of friction was high, and the tensile elongation, which is one of the mechanical properties, was also significantly reduced. These Comparative Examples 1 to 4 were considerably inferior to any of Examples 1 to 5, and were not preferable.

〔effect〕

The composition for a sliding portion material of the present invention obtained by blending carbon fiber and a calcium compound with a tetrafluoroethylene resin is more self- and more than a conventional glass fiber, carbon fiber, and a blend of various metal powders. Abrasion of the mating material can be significantly reduced, and the sliding characteristics under high PV conditions are particularly superior to soft mating materials.For example, sliding parts for aluminum mating materials such as seal rings for compressors under high PV conditions It can be a very advantageous material for manufacturing.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI (C10M 111/04 103: 02 103: 06 107: 38) C10N 10:04 20:06 40:02 50:08

Claims (1)

(57) [Claims] (1) a carbon fiber having an average fiber diameter of 1 to 20 μm and an aspect ratio of 1 to 50: 2 to 30% by weight;
0.5 to 40% by weight calcium compound powder 0.5 to 50% by weight
Of a composition for a sliding portion material, comprising: as an essential component, and the balance being ethylene tetrafluoride resin.