JPH0770580A - Swing resistant bearing - Google Patents

Abstract

(57) [Summary] [Purpose] An organic resin-based bearing with excellent anti-oscillation sliding characteristics, which is optimal for environments that continue to receive high-frequency minute vibrations. [Constitution] 100 parts by weight of COPNA resin (eg, thermosetting resin obtained by heating and condensing naphthalene and dihydroxymethylbenzene in the presence of an acid catalyst), 100 parts by weight of graphite powder and 100 parts by weight of fluororesin powder in total. 200 parts by weight and a graphite / fluorine resin weight ratio of 2/3 to 3/2 are compounded, and the resulting composition is molded and thermoset to form a bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocking resistant bearing formed of a thermosetting resin mixed with a solid lubricant and having excellent rocking resistance and sliding characteristics, and in particular, it is constantly used for automobiles and OA equipment. The present invention relates to a bearing such as a slide bearing suitable for use in an environment subject to minute vibration.

[0002]

2. Description of the Related Art Thermoplastic resins such as polyacetal, nylon and fluororesin, and thermosetting resins typified by phenol resin, graphite, fluororesin and disulfide are widely used as plastic sliding materials. There is one containing a solid lubricant powder such as molybdenum. Also,
Since heat resistance is required in so-called high load sliding applications where sliding speed and load are large, PPS (polyphenylene sulfide), PEEK (polyether ether ketone),
A mixture of super engineering plastic such as polyimide and liquid crystal polymer with a solid lubricant is used.

Although all of these super engineering plastics are expensive, they exhibit excellent heat resistance exceeding them, and as a thermosetting resin that can be produced from a cheaper raw material, a condensed polycyclic polynuclear aromatic resin (COPNA resin) is used. A resin called) has been recently developed (see Japanese Patent Laid-Open Nos. 62-521 and 62-522). This condensed polycyclic polynuclear aromatic resin is a material in which a condensed polycyclic aromatic compound (eg, naphthalene, anthracene) as a main component is combined with at least two hydroxymethyl groups and // Alternatively, it can be obtained by heat polymerization with an aromatic compound having a halomethyl group in the presence of an acid catalyst.

The thermosetting product of this condensed polycyclic polynuclear aromatic resin has a basic structure in which aromatic rings including condensed polycyclic aromatic rings are cross-linked through a methylene chain. That is, it has a cross-linking structure similar to that of a phenol resin, but does not have a hydroxyl group or the number thereof is small, and a large number of condensed polycyclic aromatic rings such as naphthalene rings are present in the molecular chain. It has excellent heat resistance, especially long-term heat resistance, and various industrial applications are currently under study.

In particular, it is known that a sliding material made of a composite material in which graphite powder is mixed with this condensed polycyclic polynuclear aromatic resin exhibits extremely excellent PV (load-speed) characteristics, wear resistance and heat resistance. (JP-A-2-215854 and 3-
84094), its applications are expanding, centering on oil-free sliding parts under high PV conditions.

[0006]

The sliding characteristics of sliding materials vary greatly depending on the sliding environment such as sliding form, PV conditions, atmosphere, etc. Virtually nonexistent. Therefore, it is necessary to develop a sliding material suitable for the sliding environment.

Recently, in the fields of automobiles and office automation equipment, there is an increasing demand for a sliding material having excellent swing resistance in order to be used as a bearing that withstands high-frequency minute vibrations. Ball bearings are difficult to handle in such an environment, and it is thought that the organic resin-based sliding materials described above are suitable, but super engineering plastic-based sliding materials such as polyimide are suitable. However, it is the current situation that no one sufficiently satisfying the anti-oscillation sliding characteristics has been obtained. On the other hand, even the above-mentioned composite material of condensed polycyclic polynuclear aromatic resin and graphite powder has a problem that material sticking occurs on the sliding surface.

Therefore, an object of the present invention is to provide a rocking resistant bearing made of an organic resin composite material having excellent rocking sliding resistance.

[0009]

In order to achieve the above object, the present inventors have studied various composite materials based on condensed polycyclic polynuclear aromatic resins, and as a result, have condensed polycyclic polynuclear aromatic resins. By combining graphite powder and fluororesin powder in a fixed ratio, the adhesion during rocking sliding is significantly improved, and rocking resistance that shows excellent rocking sliding characteristics from room temperature to high temperature range. The present invention has been achieved by finding that a flexible bearing can be obtained.

That is, the present invention provides a graphite powder and a fluororesin in an insoluble and infusible condensed polycyclic polynuclear aromatic resin having a basic structure in which aromatic rings containing condensed polycyclic aromatic rings are cross-linked through a methylene chain. It is a composite material in which powder is dispersed, and resin 100
100 to 200 in total of graphite and fluororesin with respect to parts by weight
Including parts by weight, the weight ratio of graphite / fluorine resin is 2/3 to 3 /
Characterized by being composed of a composite material within the range of 2,
The main point is rocking resistant bearings.

The condensed polycyclic polynuclear aromatic resin (hereinafter, referred to as COPNA resin) which is the matrix resin of the rocking resistant bearing according to the present invention will be described first. This resin comprises a raw material containing a condensed polycyclic aromatic compound as a main component, a cross-linking agent composed of an aromatic compound having at least two hydroxymethyl groups and / or halomethyl groups bonded to an aromatic ring, and an acid catalyst. It is a thermosetting resin produced by heating in the presence.

Examples of the condensed polycyclic aromatic compound as a raw material include naphthalene, acenaphthene, acenaphthylene, phenanthrene, anthracene, pyrene, chrysene, naphthacene, coronene, perylene, and their alkyl derivatives, naphthol, various benzopyrenes, various benzoperylene, etc. 1 type or 2 types or more of these can be used.
Further, a fused polycyclic polynuclear compound having a polynuclear structure in which two or more of these fused polycyclic aromatic compounds are linked by a bonding group such as a methylene group, a phenylene group, an ether group, and a xylylene group is also included. Further, coal-based or petroleum-based heavy oils, tar, pitch, and the like containing these compounds as main components can also be used.

The raw material contains such a condensed polycyclic aromatic compound as a main component and may partially contain a monocyclic aromatic compound. In this case, the condensed polycyclic aromatic compound preferably accounts for more than half of the mixture in molar ratio. If the amount of the monocyclic compound is too large, the heat resistance of the resulting COPNA resin may decrease. Examples of monocyclic aromatic compounds that can be used include various phenols, various alkylbenzenes, biphenyl, and biphenyl ether.

Aromatic compounds having at least two hydroxymethyl groups and / or halomethyl groups bonded to an aromatic ring, which are used as a cross-linking agent, include benzene, naphthalene, anthracene, pyrene or alkyl derivatives thereof (eg, toluene, Poly (hydroxymethyl) and poly (halomethyl) derivatives such as xylene) are included. Preferred crosslinker is di (hydroxymethyl)
Dihydroxymethyl derivatives such as benzene, di (hydroxymethyl) xylene and di (hydroxymethyl) naphthalene.

As the acid catalyst, any of Lewis acids such as aluminum chloride and boron fluoride, and protic acids such as sulfuric acid, phosphoric acid, organic sulfonic acid and carboxylic acid can be used, and a mixture of two or more kinds of acids can also be used. Can be used. Preferred acid catalysts are organic sulfonic acids such as toluene sulfonic acid, xylene sulfonic acid, phenol sulfonic acid and naphthalene sulfonic acid.

The ratio of the cross-linking agent used to the raw material is appropriately in the range of 0.7 to 6 in terms of molar ratio. Molar ratio is
When it is less than 0.7, the crosslinking is insufficient and the thermosetting property is insufficient. On the contrary, when the molar ratio exceeds 6, the crosslinking agent becomes excessive,
This gives a slightly heterogeneous resin product. The range of more preferable molar ratio is 1-3.

The amount of the acid catalyst added is 0.2 to 20% by weight, preferably 0.5 to 10% by weight based on the total weight of the raw material and the crosslinking agent.
It is within the range of weight%.

The COPNA resin can be easily prepared by mixing a raw material (condensed polycyclic aromatic compound or a mixture of the same and a monocyclic aromatic compound), a cross-linking agent and an acid catalyst at a predetermined ratio and reacting with heating. It can be manufactured. Reaction temperature is about
The temperature is 50 to 300 ° C, preferably about 80 to 200 ° C. The reaction pressure is usually normal pressure or slightly increased pressure, but the reaction can be carried out under reduced pressure in order to accelerate the removal of condensed water by-produced in the reaction from the reaction system and enhance the reaction efficiency. The reaction is easy to carry out in the molten state, but it can also be carried out in a suitable solvent or dispersion medium.

The viscosity of the reaction product increases with the progress of the reaction, and an intermediate condensate in the B stage is obtained. At this stage, it still has heat-meltability and solvent-solubility, so
It can be molded. When the reaction is further heated to proceed, an insoluble and infusible thermosetting product is produced. Therefore, in order to obtain a moldable thermosetting resin, the heating is stopped in the B stage state to stop the reaction. Thus, an intermediate condensate of thermosetting COPNA resin used for producing the bearing of the present invention is obtained.
The melt viscosity of the resin in this state is generally 10 ¹ to 10 ⁸ at 80 ° C.
It is the range of poise.

The thermosetting (B stage state) resin becomes an insoluble and infusible thermosetting material when heated to about 100 to 350 ° C. This resin can be molded and heat-cured by a method such as being powdered and hot-pressed, or melted or melted and poured into a molding die and heated to obtain various cured moldings.

The bearing of the present invention is manufactured by blending COPNA resin in the intermediate condensate (B stage) state with graphite powder and fluororesin powder, and molding and thermosetting the obtained blend into a desired shape. be able to.

The graphite powder may be any of artificial graphite, natural graphite, quiche graphite, electrode scrap, and the like. The crystallinity and particle size are not particularly limited, but scaly or flake graphite is preferable to amorphous clay graphite. Further, it is preferable that the ash content of impurities is small.

As the fluororesin, tetrafluoroethylene resin, perfluoroalkoxy resin, ethylene tetrafluoride /
Examples thereof include hexafluoropropylene copolymer resin, tetrafluoroethylene / ethylene copolymer resin, vinylidene fluoride resin, and trifluoroethylene chloride resin. Of these, tetrafluoroethylene resin is particularly preferable.

As long as the objects and effects of the present invention are not impaired, CO
In addition to the PNA resin, graphite powder and fluororesin powder, one or more kinds of various fillers, reinforcing agents, lubricants, coloring agents and the like can be added to the compound.

Graphite powder and fluororesin are COPNA resin 100
Graphite powder and fluororesin powder in total for parts by weight
100 to 200 parts by weight, and the weight ratio of graphite / fluorine resin is 2
It mix | blends so that it may become in the range of / 3-3 / 2. If the total amount of graphite powder and fluororesin powder to 100 parts by weight of COPNA resin is less than 100 parts by weight, the amount of transfer to the mating material will increase when the bearing is used, sliding resistance will increase and sticking will occur. It will be easier. On the other hand, if this total amount exceeds 200 parts by weight, the fluidity will decrease during molding of the compound, the moldability will deteriorate, and it will be difficult to perform good molding during the manufacture of the bearing.
Since the amount of resin as the binder is reduced, the mechanical properties of the bearing are also reduced.

The weight ratio of graphite / fluorine resin is 2/3 to 3 /.
Even if it deviates from the range of 2, the amount of transfer to the mating material increases during use, and the sliding resistance increases and sticking easily occurs.

The composition is, for example, pelletized thermosetting CO
PNA resin (intermediate condensate) is mixed with graphite powder, fluororesin powder and optional components optionally added in advance by dry mixing with a mixer, etc., and then melt-kneaded under heating with an appropriate device such as roll, kneader or extruder. It can be carried out.

Molding and thermosetting can be carried out by selecting from conventional methods such as compression molding, transfer molding, injection molding, etc., according to the desired shape of the bearing. The molding temperature is about 100 to 350 ° C., and the resin becomes an insoluble and infusible thermosetting material by holding the temperature for several tens of seconds to several hours depending on the molding temperature to obtain the bearing of the present invention. It is possible to further improve dimensional stability and heat resistance by performing post cure, if necessary. Post-cure conditions are usually 180 to 350 ° C. for 1 to 30 hours.

The bearing of the present invention thus obtained is a COPNA.
Thermosetting resin [that is, an aromatic ring containing a condensed polycyclic aromatic ring,
More specifically, an insoluble and infusible resin having a basic structure in which a condensed polycyclic or condensed polycyclic + monocyclic aromatic ring of a raw material and an aromatic ring of a cross-linking agent are cross-linked through a methylene chain] And a fluororesin powder dispersed composite material. This composite material contains 100 to 200 parts by weight of graphite and fluororesin in total with respect to 100 parts by weight of resin, and the weight ratio of graphite / fluororesin is in the range of 2/3 to 3/2.

[0030]

As described above, the bearing of the present invention has excellent heat resistance.
COPNA resin contains graphite powder and fluororesin powder, which have excellent lubricating effect, in a total weight of more than the resin weight, and the effect of these three components is combined to withstand high-frequency microvibration for a long time. Exhibits excellent swing resistance sliding properties.

Therefore, the bearing of the present invention is suitable for a slide bearing (flat bearing) used in an environment where high-frequency minute vibrations are applied, but can also be applied to a rolling bearing. The bearing of the present invention can be applied to both radial bearings and thrust bearings.

[0032]

EXAMPLES Materials used in this example are as follows.
Note that is a material used for comparison. COPNA resin (Sumikin Kako Co., Ltd .: SK Resin-N) B-stage state obtained by heating the raw material naphthalene with the crosslinking agent dihydroxymethylbenzene in the presence of an acid catalyst (naphthalene sulfonic acid) to cause a condensation reaction. Thermosetting intermediate condensate pellets (melt viscosity: 10 ⁵ pois at 80 ℃
e) Graphite powder (LONZA: graphite powder SK6)
(Flake graphite powder) Fluororesin powder (abbreviated as PTFE) (Kitamura: tetrafluoroethylene powder KTL600) Molybdenum disulfide (abbreviated as MoS ₂ ) (Dow Corning: Molycoat Z) carbon fiber (CF and (Abbreviated) (Kureha Chemical Industry Co., Ltd .: Kurekato
T101T) Using the above materials, dry-mixing in advance at a blending ratio shown in Table 1 using a mixer, melt-kneading for 5 minutes with a roll kneader set at 90 ° C, and crushing with a crusher to produce A compound (molding material) was prepared by granulating. afterwards,
This compound was applied at a mold temperature of 180 ° C and a molding pressure of 300 kgf / cm ²
Molded and heat-cured for 5 minutes with a transfer molding machine set under the conditions of outer diameter 23 mm, inner diameter 20 mm, height 18
A cylindrical molded body of mm 2 was obtained. This molded body was post-cured in air at 230 ° C. for 4 hours to obtain a cylindrical body usable as a bearing. This cylindrical body was used as a test piece and subjected to the following oscillating sliding test.

The oscillating sliding test was carried out by mounting this cylindrical test piece as a bearing on a shaft (counterpart material) having an outer diameter of 20 mm and oscillating the shaft under the following conditions. - mating material: SUJ2 HRC 62 (outer diameter 20 mm axial) - vibration angle × Frequency: 0.4 mm × 20 Hz diametrically 20 mm - test time: 100 hours - Pressure: 15 kgf / cm ² - ambient temperature: room temperature resistance The oscillating sliding characteristics were evaluated by the rotational resistance of the bearing (test piece) after the test and the amount of wear of the test piece. The evaluation standard of the rotation resistance of the bearing is as follows. ○: No resistance, △: With resistance, ×: Large resistance (fixed) The amount of wear of the test piece is the Rmax value obtained by measuring the sliding surface of the test piece after the oscillating sliding test with a surface roughness meter. (μm).
The test results are also shown in Table 1.

[0034]

[Table 1]

As is clear from the results shown in Table 1, a test piece of the present invention was obtained by molding and thermosetting a mixture of COPNA resin according to the present invention containing both graphite powder and PTFE powder within a predetermined range. In each case, there was no rotation resistance when rotated after the rocking sliding test, and no sign of sticking to the shaft was shown. Further, the amount of wear of the test piece after the test was also small.

On the other hand, as shown in the comparative example, COPNA
When the mixing ratio of the graphite powder and the PTFE powder to the resin is out of the range of the present invention, the rotational resistance of the test piece after the test increases,
The amount of wear also increased. In addition, when one of the graphite powder and the PTFE powder is missing, or when MoS ₂ or CF is blended in place of the PTFE powder, the rotational resistance of the test piece after the test is greatly increased, and sticking is not achieved. Showed what happened. In this case, the amount of wear of the test piece after the test also showed a large value. Especially in Test No. 12 where the amount of wear was large, the wear of the mating material was also large. Therefore, the test pieces of these comparative examples were significantly inferior in the oscillating sliding resistance to the test pieces of the present invention.

[0037]

As described above, the bearing of the present invention is excellent in oscillating sliding resistance, so that even if it is constantly exposed to high-frequency micro-vibration, it does not stick to the mating material and has good sliding characteristics. The dynamic characteristics can be retained. In addition to it,
Due to the properties of COPNA resin, it has excellent heat resistance and mechanical properties.
Moldability is also good. Therefore, the bearing of the present invention is useful in many industrial fields such as automobiles, OA equipment, general equipment, and electric / electronic equipment.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C10M 107: 38) C10N 30:00 40:02 50:08 (72) Inventor Haruyuki Kano Chiyoda, Tokyo 2-16-2 Sotokanda, Kyoto, Sumitomo Kako Co., Ltd. (72) Inventor Hidekazu Futagawa 2-16-2, Sotokanda, Chiyoda-ku, Tokyo Sumitomo Kako Co., Ltd. (72) Hisashi Hayakawa Iwata Shizuoka 28 (72) Inventor, 1725, City-find Takemi Konomoto 2092, Hatsuma, Kakegawa, Shizuoka Prefecture

Claims (1)

[Claims] 1. A graphite powder and a fluororesin powder are dispersed in an insoluble and infusible condensed polycyclic polynuclear aromatic resin having a basic structure in which an aromatic ring containing a condensed polycyclic aromatic ring is cross-linked through a methylene chain. A composite material containing 100 to 200 parts by weight of graphite and fluororesin in total with respect to 100 parts by weight of resin and having a graphite / fluororesin weight ratio within the range of 2/3 to 3/2. Become a rocking resistant bearing.