JP2000055054A - Combined layer bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combined layer bearing having a slide characteristic equal to or better than that of a conventional combined layer bearing under a high bearing even if an impregnation covering composition containing no lead or a lead compound is used. SOLUTION: This combined layer bearing comprises a porous layer 3 formed on a surface of a metal back plate and an impregnation covering composition 4 impregnated and covered in the porous layer 3. In the impregnation covering composition 4, a carbon fiber and a whisker having Mohs' hardness of 4 or less are formulated in a resin mainly containing PTFE.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer bearing, and more particularly to a multi-layer bearing having excellent sliding characteristics and abrasion resistance without the use of lead for environmental protection.

[0002]

2. Description of the Related Art A porous layer lined with a metal plate such as a steel plate is impregnated with polytetrafluoroethylene (hereinafter referred to as PTFE) and an impregnation coating composition containing lead such as lead or lead oxide. Are known as bearings having excellent sliding characteristics under high surface pressure (for example, Japanese Patent Publication Nos. 39-16950, 7-35513, and 7-35514). ). On the other hand, since the use of lead or a lead compound is not desirable for environmental protection, a bearing material using a non-toxic metal oxide composed of polyvinylidene fluoride and one of chromium oxide and iron oxide (Japanese Patent No. 2630938), A multi-layer sliding member using PTFE and phenol resin powder (Japanese Patent No. 2660853) is known.

[0003]

However, the impregnated coating containing lead or a lead compound, which is present on the sliding surface, can reduce the coefficient of friction, reduce the amount of wear, and improve the seizure resistance. The problem is that no excellent material has been found to replace the composition. In particular, lead contained in car shredder dust was reduced to 1/2, 2
According to the report of the Ministry of International Trade and Industry's Industrial Structure Council to reduce it to one-third in 005, lead-free double-layer bearings containing no lead are desired.

The present invention has been made to address such a problem, and even when an impregnated coating composition containing no lead or a lead compound is used, the same or equivalent to a conventional double-layer bearing is obtained under a high surface pressure. It is an object of the present invention to provide a multilayer bearing having equal or higher sliding characteristics.

[0005]

The multilayer bearing of the present invention comprises a porous layer formed on the surface of a metal backing metal, and an impregnated coating composition impregnated on the porous layer. The composition is characterized in that a resin containing PTFE as a main component is blended with carbon fibers and whiskers having a Mohs hardness of 4 or less.

The above impregnated coating composition has a carbon fiber content of 3 to 3
0% by volume, and whiskers with Mohs hardness of 4 or less
5% by volume, with the balance being PTFE resin.

The resin containing PTFE as a main component has a melting point of 280.
It is characterized in that a crystalline resin having a temperature of at least ℃ is further blended.

The impregnated coating composition containing a crystalline resin contains 3 to 30% by volume of carbon fibers and whiskers.
1 to 25% by volume, the crystalline resin is 5 to 40% by volume, and the balance is PTFE resin.

[0009] The crystalline resin is characterized in that it is at least one resin selected from polyphenylene sulfide resin, polyether ether ketone resin and polyimide resin.

The carbon fiber is a short fiber having a fiber length of 0.05 mm to 1 mm, and the whisker is at least one whisker selected from calcium sulfate whisker, zinc oxide whisker and potassium titanate whisker. Features.

The multilayer bearing of the present invention is constituted by an impregnated coating composition containing no lead or a lead compound by blending carbon fibers and whiskers having a Mohs hardness of 4 or less with a resin mainly composed of PTFE. In addition, by adopting this composition, it has excellent sliding properties, but also has abrasion resistance and creep resistance which are inferior to PTFE, which is inferior to resins, as well as conventional multilayer bearings containing lead or a lead compound. Equivalent or equal or higher sliding characteristics under high surface pressure can be obtained.

[0012]

FIG. 1 shows an example of a double-layer bearing of the present invention. FIG. 1 is a sectional view of a multilayer bearing. Double-layer bearing 1
A porous layer 3 of a sintered metal or the like is formed on the surface of a metal backing metal 2 such as a steel plate, and the porous layer 3 is impregnated with an impregnating coating composition 4 to form a three-layer structure. The impregnated coated surface becomes a sliding surface, and a bearing having excellent sliding characteristics under high surface pressure can be obtained.

A known resin represented by-(CF ₂ -CF ₂ ) _n- can be used for the PTFE of the present invention constituting the impregnated coating composition 4. Further, PTFE perfluoroalkyl ether group _{(-C p F 2p -O -)} (p is 1
4) or a polyfluoroalkyl group (H (CF
_{2) q} -) (q is modified P was introduced such as an integer) of 1 to 20
TFE can also be used with PTFE. For these PTFE and modified PTFE, any of a suspension polymerization method for obtaining a general molding powder and an emulsion polymerization method for obtaining a fine powder may be employed, but the number average molecular weight (Mn) is about 500,000 to 10,000,000. And more preferably, 500,000 to 3,000,000. As commercially available PTFE, Teflon 7J manufactured by DuPont-Mitsui Fluorochemicals Co., Ltd., and as commercially available modified PTFE,
DuPont Fluorochemical: Teflon TG70J, Daikin Industries: Polyflon M111, Polyflon M1
12, Hoechst: Hostaflon TFM1600, Hostaflon TFM1700 and the like.

The crystalline resin having a melting point of 280 ° C. or higher according to the present invention is excellent in heat resistance and can improve abrasion resistance and creep resistance in a mixture of carbon fiber and whisker having a Mohs hardness of 4 or less with PTFE. Any resin that can be used can be used. For example, polyphenylene sulfide resin, polyether ether ketone resin, polyimide resin, polyether ketone resin, nylon 46 resin and the like can be mentioned. Among these, polyphenylene sulfide resin, polyether ether ketone resin, and polyimide resin, which can further improve the wear resistance and creep resistance, are preferable, and the most preferable is polyphenylene sulfide resin.

The carbon fiber according to the present invention can be used in any of pitch-based or PAN-based as long as it can reinforce the impregnated coating composition by being used in combination with a whisker described later. The carbon fiber preferably has a fiber length of 0.05 mm to 1 mm, and more preferably 0.05 m.
m to 0.1 mm. The fiber diameter is φ20 μm or less, preferably φ7 μm to φ15 μm, and the aspect ratio is 5 to 8
0, preferably 20 to 50. If the carbon fiber having this property, excellent effect of reinforcing the impregnated coating composition,
Excellent wear and creep resistance. The type of yarn is not particularly limited.
Is preferred. Regarding the firing temperature, a low-temperature fired product aimed at low elasticity or a high-temperature fired product aimed at high elasticity can be used.

A commercially available carbon fiber is available as pitch material from Kureha Chemical Co., Ltd .: Crecamild M101S, M101F, M
101T, M107S, M1007S, M201S, M
207S, manufactured by Osaka Gas Chemical Company: Donna Carbon S24
1, S244, SG241, SG244 as PAN system, manufactured by Toho Rayon Co., Ltd .: Vesfight HTA-CMF
0160-0H and CMF0070-0H.

The whisker having a Mohs' hardness of 4 or less according to the present invention can be used as long as it plays a role of micro reinforcement in the impregnated coating composition and can contribute to improvement of creep resistance and abrasion resistance. In the present invention, the reason for setting the Mohs' hardness to 4 or less is to improve the friction and wear characteristics. Examples of whiskers having a Mohs hardness of 4 or less include calcium sulfate whiskers, potassium titanate whiskers, zinc oxide whiskers, and magnesium sulfate whiskers. Among these, calcium sulfate whiskers, zinc oxide whiskers, and potassium titanate whiskers are particularly preferable. Further, since the whisker has a smaller overall shape than the carbon fiber, the whisker has a large proportion on the friction surface, and is responsible for most of the frictional shear, so that the mating material is not damaged. However, if the fiber length of the whisker is too short, sufficient creep resistance and abrasion resistance cannot be obtained, and the fiber length is preferably about 50 μm, which is slightly shorter than carbon fiber.
The whisker corresponding to this includes an anhydrous salt type and a hemihydrate salt type of calcium sulfate whisker, and is preferably an anhydrous salt type.

Commercially available whiskers having a Mohs hardness of 4 or less are:
As calcium sulfate whisker, manufactured by Dainichi Seika Kogyo: Franklin Fiber A-30 (anhydrous salt type, Mohs hardness)
2-3, fiber length 50-60 μm), H-30 (hemihydrate salt, Mohs hardness 2-3, fiber length 50-60 μm), potassium titanate whisker manufactured by Otsuka Chemical Co., Ltd .: Tismo N (Mohs Hardness 4, fiber length 10-20 μm), manufactured by Kawatetsu Mining Co., Ltd .: Thaibreck (Mohs hardness 4, fiber length 20 μm)
), Zinc oxide whiskers, manufactured by Matsushita Electric Industrial Co., Ltd .: zinc oxide whiskers (Mohs hardness 4, fiber length 2-50 μm)
), Magnesium sulfate whisker, manufactured by Ube Industries: Moss Heidi (Mohs hardness 2.5, fiber length 10-30 μm)
).

The compounding ratio in the impregnated coating composition is as follows: 3 to 30% by volume of carbon fibers and whiskers having a Mohs hardness of 4 or less.
Preferably, the content is 1 to 25% by volume, and the balance is PTFE resin. When a part of the PTFE resin is replaced with a crystalline resin having a melting point of 280 ° C. or higher, the mixing ratio is 3 to 30% by volume of carbon fiber and 1 to 25% by volume of whisker having Mohs hardness of 4 or less. Preferably, the crystalline resin having a melting point of 280 ° C. or more is 5 to 40% by volume, and the remainder is PTFE resin. If the amount of the carbon fiber exceeds 30% by volume, there is a problem in formability. If the amount is less than 3% by volume, the reinforcing effect is poor and sufficient creep resistance and wear resistance cannot be obtained. If the whisker having a Mohs' hardness of 4 or less exceeds 25% by volume, molding becomes difficult. When the crystalline resin having a melting point of 280 ° C. or more exceeds 40% by volume, the friction coefficient increases under a high load, causing problems such as an increase in initial torque and an increase in heat generation due to friction. No effect. P
The amount of the TFE resin may be the balance of the total amount.

It is to be noted that known additives listed below can be blended within a range not to impair the object of the present invention.
For example, PTFE lubricating powder, wear reinforcing agent such as molybdenum disulfide, carbonized powder, electric property improving agent such as zinc oxide and titanium oxide, cracking property improving agent such as graphite, and metals having environmental pollution potential such as lead and cadmium. Other metal oxide powders excluding, heat conductivity improvers such as graphite, improvement in toughness such as tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) Agents can be mentioned.

As the metal backing metal 2 according to the present invention, steel (S
Rolled steel for structural use such as PCC) or a metal other than steel, for example, a copper-based alloy such as stainless steel or bronze can be used. Further, it is preferable that the back metal surface be plated (copper or a copper alloy such as bronze) equivalent to the sintered metal layer in order to enhance the adhesion to the sintered metal layer. As the porous layer 3 according to the present invention, a sintered metal layer is preferable, and as the sintered metal layer, a copper alloy such as copper or bronze is preferable because of its excellent friction and wear characteristics.

The multilayer bearing of the present invention has excellent sliding characteristics under high surface pressure without blending lead or a lead compound.
Resin bearings can be used in fields where cracking and chipping are likely to occur, or in the fields of automobile parts and home electric parts.

[0023]

EXAMPLES Raw materials used in Examples and Comparative Examples are collectively shown below. The numbers in parentheses for the raw materials correspond to the raw material numbers shown in the table. (1) Polytetrafluoroethylene [PTFE] Mitsui
Dupont Fluorochemicals: Teflon 7J (2) Polyphenylene sulfide [PPS] Tosoh: B160 (melting point: 288 ° C) (3) Polyimide [PI] Mitsui Chemicals: Aurum 45
0 (melting point: 388 ° C.) (4) Polyetheretherketone [PEEK] manufactured by Mitsui Chemicals: Victrex 450P (melting point: 334 ° C.) 100μm, fiber diameter 14.5μ
m) (6) PAN-based carbon fiber [CF-2] manufactured by Toho Rayon Co., Ltd .: Vesfight HTA-CMF0160-0H (fiber length 160 μm, fiber diameter 7 μm) (7) Pitch-based carbon fiber [CF-3] manufactured by Kureha Chemical : Crecamyl M107S (fiber length 700μm, fiber diameter 14.5μ)
m) (8) Pitch-based carbon fiber [CF-4] manufactured by Kureha Chemical: Crecamild M101T (fiber length 100 μm, fiber diameter 18 μm)
(9) Calcium sulfate whisker [Calcium sulfate W] manufactured by Dainippon Seika Kogyo: Franklin Fiber A-30
(Anhydrous salt type, Mohs hardness 2-3, fiber length 50-60μm
(10) Zinc oxide whisker [Zinc oxide W] manufactured by Matsushita Electric Industrial Co., Ltd .: Zinc oxide whisker (Mohs hardness 4, fiber length 2 to 50)
μm) (11) Potassium titanate whisker [potassium titanate W] manufactured by Otsuka Chemical Co., Ltd .: Teismo N (Mohs hardness 4, fiber length)
10 to 20 μm)

Examples 1 to 13 The multilayer bearings of Examples 1 to 13 were produced by the following method. After the stainless steel (SUS304) steel plate is degreased, copper plating is performed, and bronze powder (# 10
The one that passes 0 mesh and turns on with # 200 mesh)
Was sprayed. Heats the steel sheet on which the bronze powder is evenly dispersed.
By pressing, a porous layer having a uniform layer thickness was formed.
On this porous layer, PT adjusted to the compounding ratio shown in Table 1 was used.
The dispersion of FE resin particles was applied, the solvent was evaporated in a drying oven, and the porous layer was impregnated with the resin component by heating and pressing. The plate material of the multilayer bearing thus obtained was processed into a predetermined test piece shape, and the dynamic friction coefficient and the wear amount were measured by a ring-on-disk tester. FIG. 2 shows an outline of the ring-on-disk tester. The ring-on-disk type testing machine is a testing device that measures a dynamic friction coefficient and a wear amount by rotating a test piece 6 under a predetermined condition with respect to a counterpart material 5 to which a pressing force is applied and fixed. Reference numeral 7 denotes a load cell. The test conditions were as follows: speed 150m / min, surface pressure 1.37
The test was carried out at MPa for 20 hours, and the dynamic friction coefficient and wear amount immediately before the end of the test were measured. Table 3 shows the measurement results.

Comparative Example 1 and Comparative Example 2 A multilayer bearing was produced in the same manner as in Example 1 except that the dispersion of PTFE resin particles adjusted to the compounding ratio shown in Table 2 was applied. The plate material of the obtained multilayer bearing was evaluated using the same ring-on-disk test machine as in Example 1. Table 4 shows the results.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

As is evident from the results in Tables 3 and 4, Comparative Example 2, which does not contain conventional lead, exhibited the lowest friction and wear characteristics among Examples and Comparative Examples. On the other hand, the dynamic friction coefficients of the multilayer bearings of Examples 1 to 13 were equal to or higher than those of Comparative Example 1 containing conventional lead, and the wear amount was clearly superior.

[0031]

The double-layer bearing according to the present invention is characterized in that the impregnating coating composition to be impregnated is a mixture of PTFE-based resin with carbon fibers and whiskers having a Mohs hardness of 4 or less. Is not included at all. As a result, it is excellent in environmental conservation. Also, it has excellent sliding characteristics and wear resistance even under high surface pressure.

Further, the compounding ratio of the impregnated coating composition was 3 to 30% by volume of carbon fiber, 1 to 25% by volume of whiskers, and the balance was P
Since the TFE resin is used, the above-described characteristics are further improved.

The PTFE resin is further blended with a crystalline resin having a melting point of 280 ° C. or higher.
Volume%, whisker 1 ~ 25 volume%, crystalline resin 5 ~ 40
Since the volume% and the balance are PTFE resin, the sliding characteristics and wear resistance are excellent even under high surface pressure, and the creep resistance is further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multilayer bearing.

FIG. 2 is a diagram showing an outline of a ring-on-disk type testing machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 multilayer bearing 2 metal backing 3 porous layer 4 impregnated coating composition 5 mating material 6 test piece 7 load cell

 ──────────────────────────────────────────────────続 き Continued from the front page F term (reference) JK09 JK12B JK16 YY00B

Claims (7)

[Claims] 1. A multilayer bearing comprising a porous layer formed on the surface of a metal backing metal and an impregnated coating composition impregnated on the porous layer, wherein the impregnated coating composition is polytetrafluoroethylene. A multi-layer bearing comprising carbon fibers and whiskers having a Mohs hardness of 4 or less mixed with a resin mainly composed of: 2. The impregnated coating composition, wherein the carbon fiber is
3 to 30% by volume, and the whisker is 1 to 25% by volume.
The multilayer bearing according to claim 1, wherein the balance is a polytetrafluoroethylene resin. 3. The multilayer bearing according to claim 1, wherein said resin is a crystalline resin having a melting point of 280 ° C. or higher. 4. The impregnated coating composition according to claim 1, wherein the carbon fibers are
3 to 30% by volume, and the whisker is 1 to 25% by volume.
The multilayer bearing according to claim 3, wherein the crystalline resin is 5 to 40% by volume and the balance is a polytetrafluoroethylene resin. 5. The multilayer bearing according to claim 3, wherein the crystalline resin is at least one resin selected from a polyphenylene sulfide resin, a polyether ether ketone resin, and a polyimide resin. . 6. The method according to claim 1, wherein the carbon fiber has a fiber length of 0.05 mm to 1 mm.
The multilayered bearing according to any one of claims 1 to 5, characterized in that the multilayered bearing is a short fiber. 7. The whisker according to claim 1, wherein the whisker is at least one whisker selected from calcium sulfate whiskers, zinc oxide whiskers, and potassium titanate whiskers. Double layer bearing.