JPH0115531B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a sliding member used in a bearing or a mechanical seal. [Prior Art] Many sliding members are known that use thermoplastic resins or thermosetting resins as binders and contain various lubricant powders. Conventional sliding members have a structure in which the main component of the matrix is thermosetting resin or thermoplastic resin as a binder, and solid lubricant powder such as fluororesin, molybdenum disulfide, graphite, etc. is dispersed in the matrix. It was full of giblets. [Object of the Invention] The present invention is based on the discovery that a sliding material with a low coefficient of friction can be obtained by dispersing a fluororesin in the form of fibers in a matrix containing carbon graphite powder, and based on this discovery. This was achieved by An object of the present invention is to provide a sliding member containing a fluororesin having a low coefficient of friction. [Structure of the Invention] The sliding member of the present invention includes a binder made of polyacetal, phenol resin, epoxy resin, or a mixture thereof, and carbon graphite in a blending ratio of 30 to 70% by weight when the total weight is 100%. % of a lubricating powder containing carbon graphite powder, which is dispersed in the matrix in the form of fibers and has a blending ratio of 0.2 to 30% by weight when the total weight is 100%. % of fluororesin as the main component. [Detailed Description of the Structure of the Invention] The fluororesin of the present invention is dispersed in the form of fibers in a matrix that is the main component of the sliding material. The fibrous dispersion in the matrix includes PTFE powder for compression molding called molding powder, PTFE powder for extrusion molding called fine powder,
It is obtained by kneading one or more types of PTFE powder extracted from an aqueous impregnating solution called PTFE dispersion and a matrix component.
The total blending ratio of fluororesin components is 100% by weight.
(Hereinafter, % means % by weight, and unless otherwise specified, the total is 100% by weight) 0.2 to 30%
It is. If it is less than 0.2%, the effect is not sufficient. Furthermore, if it exceeds 30%, a large amount of force is required for kneading, making kneading difficult. The thickness of the fibrous fluororesin dispersed in the matrix is 0.1~
It is about 10μ. Incidentally, a scanning electron micrograph of the fibrous fluororesin is shown in FIG. The white, fibrous-looking material is fluororesin. Note that in this photo, the matrix portion is made of polyacetal resin. The matrix is comprised of a mixture of a binder and a lubricating powder containing carbon graphite. This matrix serves as a medium for the above-mentioned fibrous fluororesin and serves as the base of the sliding member. Both thermoplastic resins and thermosetting resins can be used as the binder. As the thermoplastic resin, resins such as polyacetal, polybutylene terephthalate, and nylon, particularly crystalline resins, are preferable. As the thermosetting resin, modified phenolic resins such as straight phenolic resin, epoxy modified phenolic resin, and melamine modified phenolic resin, thermosetting resins such as epoxy resin, melamine resin, urea resin, polyimide, and polyamideimide can be used. can. In particular, straight phenolic resin and modified phenolic resin provide excellent frictional properties. The lubricating powder constituting the matrix together with the binder includes at least carbon graphite powder, which is a solid lubricant. As other lubricating powders,
Examples include solid lubricants other than carbon graphite powder, powders adsorbed or impregnated with lubricating oil, and hard powders that improve load carrying capacity, improve wear resistance, or prevent adhesion of binders to mating materials. The above-mentioned carbon graphite powder can be used as a main component constituting the matrix in addition to acting as a solid lubricant. As the carbon graphite powder, not only perfect graphite but also incomplete graphite, so-called carbon graphite, etc. can be used. Crystal-wise, it is graphite with a lattice spacing in the (002) direction of graphite crystals of 3.500 Å or less, preferably larger than 3.354.
It is better to use graphite with a degree smaller than 3.410.
Further, either natural graphite or artificial graphite may be used. Any of the known natural graphites, such as earthy graphite, scaly graphite, flaky graphite, and lump graphite, can be used. The blending ratio of carbon graphite is 30 to 70
%, preferably 50 to 60%. This is because if it is less than 30%, the friction properties will deteriorate, and if it is more than 70%, the strength will be reduced. The powder diameter of carbon graphite is
The thickness is preferably about 0.5 to 200μ, particularly about 2 to 100μ. This is because sufficient frictional properties can be obtained and the bonding force with the resin will also be sufficient. When blending a large amount of lubricating powder, it is preferable to use a thermosetting resin as the binder. In this case, the blending ratio of the thermosetting resin is 20 to 50%, particularly 25 to 35%. Other solid lubricants include molybdenum disulfide, mica, boron nitride, and the like. these are
Approximately 0.5 to 15% can be blended. In particular, those containing about 1 to 10% are excellent. The particle size is preferably 100μ or less. Lubricating oils used for powders adsorbed and impregnated with lubricating oil include silicone oil, heat-resistant synthetic oil,
Olefin oil, paraffin oil, general mineral oil, etc. can be used. In addition, since the oil-impregnated sliding member of the present invention may have a molding temperature and sliding temperature of about 140°C in the short term,
Preferably, the oil has heat resistance of about 140°C. The proportion of lubricating oil is approximately 0.5 to 15% by weight.
In particular, it is preferably about 3 to 8%. Adsorbents for lubricating oil include wood flour, powdered cellulose, porous organic and inorganic powders with large surface areas,
Layered minerals, fibrous powders, etc. can be used. Note that carbon graphite powder can also be used as an adsorbent. Hard powders include carbides such as silicon carbide, titanium carbide, and tungsten carbide, nitrides such as silicon nitride and boron nitride, and oxides such as alumina, silica, titania, magnesia, manganese oxide, calcium oxide, iron oxide, and chromium oxide. , mica, glass beads, ferrite, glass fiber, talc, etc. can be used. It should be noted that the hard powder actually acts as a hard powder if it is a substance that is hard due to the main components such as the binder constituting the matrix. However, harder materials are preferred. The particle size of the hard powder is preferably about 0.5 to 200μ, particularly about 2 to 150μ. The blending ratio is 25% or less, about 5 to 25%, more preferably 8
~20%. The sliding member of the present invention can be manufactured by mixing and kneading the above-mentioned components, dispersing the fluororesin in the form of fibers in a matrix, and compression molding in a mold, or by injection molding in a mold. can. During this molding, it can be molded into a shape suitable for a bearing or a sealing material for a mechanical seal. Further, after molding, it can be mechanically ground or cut to give a certain shape. [Effects of the Invention] In the sliding member of the present invention, since the fluorocarbon resin is in the form of fibers, the friction coefficient is smaller than that of conventional fluorocarbon resins dispersed in the form of particles. Therefore, in order to obtain the same coefficient of friction as the conventional one, it is only necessary to mix a small proportion of fluororesin. Furthermore, since the fluororesin is dispersed in the matrix in the form of fibers, the fluororesin itself is less likely to fall off from the matrix than when it is dispersed in the form of particles. That is, most of the fibrous fluororesin exposed on the friction surface is present in the matrix, so it is less likely to fall off than the friction surface. In addition, since the fluororesin used is of a type with excellent ductility, it is thought that it will stretch on the friction surface and cover a wide range of the friction surface with the fluororesin. Therefore, it is thought that fluororesin accumulates on the friction surface and the proportion of fluororesin becomes high. This seems to be the factor giving the low coefficient of friction. And, when such fibrous fluororesin accounts for 100% by weight of the whole, it is 0.2~
By blending 30% by weight, the above-mentioned effects are sufficient. Further, the sliding member of the present invention contains carbon graphite powder, which is a solid lubricant, in the matrix portion. The carbon graphite powder is dispersed in a binder to form a matrix. This prevents the bonding agent from adhering to the surface of the mating material, and
The solid lubricant itself acts as a lubricant and enables smooth sliding. This carbon graphite powder has a small coefficient of friction, so it has a great low friction effect. When molybdenum disulfide is further used as a solid lubricant, low friction can be achieved as molybdenum disulfide itself is known as an excellent solid lubricant. When a hard powder is blended in addition to the carbon graphite powder in the sliding member, the hard powder has the effect of scraping off the binder adhered to the sliding surface of the mating member. Therefore, by containing a hard material, friction is stabilized over a long period of time, and low friction can be obtained. Further, in this case, the respective effects as a hard powder and a solid lubricant are exhibited. For example, when a phenolic resin is used as a binder, the hard material and carbon graphite powder as a solid lubricant tend to be independent of each other, so the hard material and carbon graphite powder are dispersed in the phenol resin, and the more phenol Since the resin is dispersed, it is possible to prevent the phenolic resin from adhering to the mating material. Note that the fibrous fluororesin further strengthens the retention of hard materials, and can prevent the hard powder from deteriorating to some extent. When a lubricating oil-impregnated powder is blended in addition to the carbon graphite powder, the lubricating oil is supplied to the sliding surfaces, thereby achieving low friction. Furthermore, the lubricating oil acts to prevent the bonding agent from adhering to the mating material. Note that as a mating material for the sliding member of the present invention, an oil-impregnated ceramic material such as oil-impregnated alumina is most suitable. In particular, the sliding member of the present invention can be effectively used for mechanical seals using oil-impregnated alumina as a mating material. [Test Example 1] As Test Example 1, the effects of fibrous PTFE and granular PTFE on the coefficient of friction are shown for reference. PTFE molding powder was used as a binder. They were blended at the blending ratios No. 1 to No. 7 shown in Table 1, kneaded in a twin-screw kneading extruder, and then granulated and injection molded. The obtained molded body was cut to form a sliding material having an inner diameter of 16 mm, an outer diameter of 21 mm, and a thickness of 7 mm. Next, an alumina ring made of sintered alumina was used as a mating material, and the load was 5 kg and the speed was 0.2.
The test was carried out using a ring-ring type friction and wear tester at a speed of m/sec in water for 1 hour. In this test, each sliding member was fixed and the mating member was rotated. Thereby, the average coefficient of friction was determined. The results obtained are shown in Table 1. And for comparison, 100% polyacetal
and pulverized molded body with 86% polyacetal
A sliding member obtained by kneading PTFE powder was manufactured in the same manner as above. These were also subjected to the same test as above to determine the friction coefficient. The results are also shown in Table 1. Looking at the coefficient of friction of the sliding material obtained, it is No.1.
As you can see when comparing No. 102, it is only 0.2%
Just because it contains fibrous PTFE, the coefficient of friction is
It decreased by 0.02. Also, by comparing No. 6 and No. 101,
The blending ratio of PTFE is 14% in both cases, but the fibrous
The friction coefficient of No. 6 containing PTFE is 0.21, while the friction coefficient of No. 101 containing particulate PTFE is 0.31. This clearly shows the effect of fibrous PTFE. For reference, a scanning electron micrograph of the composition of sliding member No. 4 is shown in Figure 1.
A microscopic photograph of the composition of sliding member No. 101 is shown in FIG. The white fibrous material in Figure 1 is PTFE.
On the other hand, the black particles in Figure 2 are PTFE. [Test Example 2] Phenol resin, epoxy resin, and polyacetal were used as the binder, so-called carbon graphite (particle size 80μ or less), which is an artificial carbon graphite powder, was used as the carbon graphite powder, and fibrous fluororesin was used. PTFE molding powder was used as the material. Then, carbon graphite powder and a binder were kneaded at the respective mixing ratios shown in Table 2 to obtain molded powders. The mixture was mixed using a Hensel mixer or the like, and then kneaded using a hottrol, co-kneader, or the like. No. 9 was molded in the same manner as Test Example 1. The rest was molded for about 3 minutes at 155°C and a molding pressure of 200 kg/cm ² in the same manner as the usual molding method for phenolic resin. The obtained molded body was cut in the same manner as in Test Example 1, and the same sliding test was conducted. Second result
Shown in the table. As can be seen by comparing the results in Tables 1 and 2, No. 2 and No. 9 have the same blending ratio of fibrous PTFE.
Among the samples, the friction coefficient of sample No. 9, which contains 30% carbon graphite powder, is 0.02 lower than that of sample No. 2, which does not contain carbon graphite powder. i.e. carbon graphite powder 30~70
%, the friction coefficient is lowered by about 0.02 compared to the sliding member of Test Example 1. Also, if fibrous PTFE is not included, No.
As is clear from samples No. 103 and No. 104, they exhibit large friction coefficients of 0.37 and 0.32. However, by incorporating 0.2% fibrous PTFE, the friction coefficient
0.32, and it can be seen that by blending 3.1 or more, the friction coefficient becomes 0.24 or less. [Test Example 3] As in Test Example 2, phenolic resin, Epoquine resin, polyacetal, fibrous PTFE, and carbon graphite were used, and silica with a particle size of 25μ or less and alumina with a particle size of 10μ or less were used as hard powders. , each sliding member was manufactured using the compounding ratios shown in Table 3. Then, a test was conducted in the same manner as in Test Example 1. The friction coefficients obtained in this test are also shown in Table 3. It is clear that by blending silica or alumina, the coefficient of friction becomes 0.16 to 0.23, making it extremely stable. Furthermore, the friction coefficient is significantly lower than the friction coefficient of 0.35 of sliding member No. 105, which does not contain fibrous PTFE. [Test Example 4] In addition to the phenolic resin or polyacetal, carbon graphite, and fibrous fluororesin of Test Example 2, molybdenum disulfide (average particle size of about 5 μ), which is known as a lubricant, and low molecular weight tetrafluoride were used. A sliding member was obtained in the same manner as in Test Example 1 using ethylene resin powder, boron nitride (particle size: approximately 10 μm), and silicone oil (previously impregnated and adsorbed onto carbon graphite). Further, the obtained sliding member was tested in the same manner as in Test Example 1. Combining the obtained friction coefficients, the fourth
Shown in the table. Addition of lubricant further lowers and stabilizes the friction coefficient, resulting in a small friction coefficient of about 0.11 to 0.23. In particular, by impregnating it with silicone oil, a material with a friction coefficient as low as 0.11 was obtained. [Test Example 5] A sliding member containing silica or alumina as a hard material and one or two types of lubricant was
Shown in the table. The sliding members shown in Table 5 were also manufactured in the same manner as Test Example 1. Further, test results obtained in the same manner as in Test Example 1 are also shown in Table 5. It can be seen that the friction coefficient is low and stable at 0.16 to 0.23. Note that sliding member No. 106 shown as a comparative example has a high coefficient of friction of 0.33.
This is because the fibers in the matrix

【table】

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【table】 This is probably because it does not contain PTFE.

[Brief explanation of drawings]

Fig. 1 is a microscopic photograph showing the fiber shape of the structure of No. 4 sliding member shown in Test Example 1, and Fig. 2 is a scanning electron micrograph showing the particle shape of the structure of the sliding member of Comparative Example. be.

Claims (1)

[Scope of Claims] 1. Carbon graphite in which the blending ratio of a binder made of polyacetal, phenolic resin, epoxy resin, or a mixture thereof and carbon graphite is 30 to 70% by weight when the total weight is 100%. A matrix portion composed of a mixture of lubricating powder containing powder, and a matrix portion that is dispersed in the matrix portion in the form of fibers and that is
The blending ratio is 0.2 to 30% by weight when it is 100% by weight.
A sliding member characterized by having a fluorine resin as a main component. 2. The sliding member according to claim 1, wherein the fibrous dispersion of the fluororesin is obtained by kneading with the matrix portion. 3. The sliding member according to claim 1, wherein the matrix portion contains hard powder. 4. The sliding member according to claim 1, wherein the matrix portion contains solid lubricant or powder adsorbing lubricating oil. 5. The sliding member according to claim 4, wherein the interplanar spacing in the (002) direction of the graphite crystals forming the carbon graphite is 3.500 Å or less, and the lubricating oil is adsorbed on the carbon graphite. 6. The sliding member according to claim 1, wherein the matrix portion contains hard powder and powder adsorbing solid lubricant or lubricating oil.