JPH07188500A - Lubricating rubber composition - Google Patents

Abstract

PURPOSE:To obtain a long-life composition excellent in static and dynamic frictional properties and abrasion resistance by mixing a fluororubber with a specified tetrafluoroethylene resin powder and spherical graphite. CONSTITUTION:This composition is obtained by mixing a fluororubber with a tetrafluoroethylene resin powder with its surface pierced by a carbon material and spherical graphite. 'The tetrafluoroethylene with its surface pierced by a carbon material' means one obtained for example by coprecipitation with a carbon material at the end of the emulsion polymerization, and coagulating, washing and drying the coprecipitate. It may be one obtained by dry-blending a tetrafluoroethylene resin powder with a carbon material. The carbon materials include usual carbon powders and graphite powders, and graphite is particularly desirable. The spherical graphite is one produced as a by-product in spinning of pitch or one prepared by reacting a phenolic resin with paraformaldehyde in the presence of a catalyst to form a spherical polymer, and firing and grinding this polymer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lubricating rubber composition.

[0002]

2. Description of the Related Art Fluorine rubber (hereinafter referred to as FPM) is
It is a special rubber that is excellent in heat resistance, weather resistance, oil resistance, chemical resistance and ozone resistance, and is usually used in harsh applications where the above characteristics are utilized. But most of them
It is used for sealing and vibration absorption in the fields of general industrial use, military use, space use, civilian use, medical use and the like. Many of them also use sliding, and most of them are used in combination with grease or oil.

For example, in the case of the seal component, the material has been selected to the extent that the type of fluororubber is selected or the hardness is selected according to the filler ratio in consideration of only the usage conditions such as the atmosphere. Due to the shearing force generated in the moving part, heat is generated, oil and grease are discharged, stick slip occurs, and normal operation is not stabilized, or abnormal noise occurs, which is a problem. Further, as the worst result, there was a case in which wear progressed, breakage, breakage, etc. occurred, and replacement was required in a short period of time.

For example, general oil seals around oil in automobiles and motorcycles, oil sheets for gasoline supply system, seals for air supply / exhaust systems, seals for air conditioner refrigerants, wiper blades, glass run, seals around toner in electronic copying machines for office equipment, Toner blade for fixing unit, seal for switching valve of cup juice vending machine, seal for household water purifier / mixing stopper, seal for switching valve of general production line, seal for bread / mochi kneading machine, butterfly for tap water / sewage There are countless seals for valves, medical syringe piston seals, etc.

To improve the sliding properties of rubber materials in general, a diene-based synthetic rubber having a Teflon sheet attached to the surface of the seal / sliding part of the seal has been used (Japanese Patent Publication No. 46-23681). Description). But,
Since it is exposed to high pressure for a long period of time, peeling of the adhesive portion is a problem. Also, since the sliding surface is not an elastic body,
Sealing property is not sufficiently satisfied. Naturally, the adhesion to the surface of the fluororubber has not been put to practical use because it is more uneasy.

[0006] To give a sealing property and a low friction holding property,
A type in which a diene rubber base material was impregnated with oil was also examined, but the oil was discharged over time, and the sliding resistance gradually increased, causing problems such as stick-slip and damage. Teflon coating on the surface of the seal portion was also tried, but there was a problem of heat resistance of the rubber base material against the firing conditions of the coating film, and the wear resistance was not sufficient in the usable class. In addition, the film does not have sufficient followability to the substrate, and the film peels off due to stretching and movement during component mounting. Further, a chemical solution treatment or a plasma treatment with a chlorine-based solvent, which is carried out with a wiper blade or the like, has been devised, but none of them has been sufficient.

Fusion of an olefinic polymer to the seal portion as in the invention described in Japanese Patent Publication No. 57-32950 was also investigated, but the sealing property was lost and it could not be used. Many commonly known solid lubricants such as Teflon and silicone are added to diene rubber to give low friction durability, and many have been devised, and patent applications or academic conference reports have been provided. Although some low friction was achieved,
The addition of these materials resulted in high hardness and insufficient sealing properties, and they were not usable. Further, since the wettability with the rubber substrate is poor, the tensile strength and the tear strength are extremely lowered, and the abrasion resistance is inferior to that of the conventional product. Silicone rubber and fluororubber were also targeted, but no significant significance was observed.

[0008]

Therefore, in any of the applications, there is a demand for a lubricating rubber material which is excellent in static and dynamic friction durability, is excellent in wear resistance, and has a long life and can be used reliably. The problem is to provide a lubricating rubber composition that can meet this demand.

[0009]

In order to solve the above-mentioned problems, the present invention adopts a constitution in which FPM, tetrafluoroethylene resin powder having a carbon material stuck on the surface thereof, and spherical graphite are blended. Is. The details will be described below.

First, the FPM in the present invention can be exemplified in a wide range as long as it is synthesized by various organic synthesis methods and has rubber-like elasticity at room temperature. This FP
The molecular weight of M is usually preferably 50,000 or more, and a high molecular weight is preferable to obtain a good result. Therefore, a molecular weight of M is more preferably 70,000 or more, particularly preferably 100,000 to 500,000. . As a typical example corresponding to the above conditions, a tetrafluoroethylene / polypropylene copolymer manufactured by Asahi Glass Co., Ltd.
Aflas Showa Denko Co., Ltd. Vinylidene-6-Fluorofluorene Copolymer Viton Montefluos Co. Vinylidin-6-Fluorofluorene Copolymer Technoflon Toshiba Silicone Fluorosilicone Sumitomo 3M Hydrofinyl An example is hexafluorofluorene copolymer copolymer Florel.

The tetrafluoroethylene resin having the carbon material stuck to the surface is, for example, a tetrafluoroethylene resin having the carbon material stuck to the surface after coprecipitation with the carbon material at the end of emulsion polymerization, coagulation, washing and drying. is there.

A carbon material may be mixed with the tetrafluoroethylene resin powder by dry mixing and the surface may be pierced with the carbon material. It should be noted that the carbon material is powdered from general carbon powder to graphite, and particularly graphite is preferable, and HAF carbon, SAF carbon, M having a large structure which is generally used as a rubber base material.
You may use together with T carbon etc.

As shown in FIG. 1, since graphite 2 is pierced in all directions in tetrafluoroethylene resin (indicated as PTFE in the figure) 1, a physical pile effect in rubber base material 3 is obtained. It is considered that, due to the affinity of the rubber base material and graphite, a material having a higher strength than that obtained by simply kneading the rubber base material and the tetrafluoroethylene resin can be obtained.

The spheroidal graphite in the present invention means spheroidal graphite produced as a by-product in the process of spinning from pitch, or phenolic resin is reacted with paraform under a catalyst to polymerize into spheres, which is then calcined and pulverized. Spherical graphite may be used. The commercially available products are exemplified below. Osaka Gas Chemical's Mesocarbon beads Kanebo's Bell Pearl Unitika's Univex Nippon Carbon's micro carbon beads.

In the present invention, the weight ratio of FPM to tetrafluoroethylene resin is preferably 10 parts by weight or more and less than 140 parts by weight with respect to 100 parts by weight of FPM. If the amount of the tetrafluoroethylene resin is less than 10 parts by weight, the FPM cannot be provided with sufficient friction characteristics. On the contrary, when it exceeds 140 parts by weight, the rubber hardness becomes high, the rubber characteristic is lost, and the mechanical strength is extremely lowered, so that it cannot be used in actual use.

In the present invention, the filling weight ratio of spherical graphite to 100 parts by weight of FPM is preferably 5 parts by weight or more and less than 80 parts by weight. If the amount of spheroidal graphite is less than 5 parts by weight, sufficient wear resistance cannot be imparted to FPM. On the other hand, if the amount exceeds 80 parts by weight, the rubber hardness becomes high, the rubber properties are lost, and the mechanical strength extremely decreases, so that it cannot be used in actual use.

It should be noted that known additives as listed below may be blended within a range not impairing the object of the present invention.

(1) Reinforcing agent For example, carbon black,
Silica, clay, calcium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum oxide, talc,
Mica, kaolin, bentonite, shirasu, wollastonite, silicon carbide, glass powder, carbon powder, boron fiber, aramid fiber, etc. (2) Vulcanization aids, for example, polyols, peroxides, polyamines, etc. (3) Vulcanization acceleration Agents, for example, guanidines, sulfur, aldehyde-amines, zinc salts, etc. (4) Vulcanization activators, for example, magnesium oxide, calcium hydroxide, lead oxide, etc. (5) Plasticizers, for example, fluorinated oils, etc. (6) Anti-aging agent For example, amines, phenols, etc. (7) Compatibilizer (8) Colorant The method of kneading the above various raw materials is not particularly limited, and a method that is generally widely used, for example, a main raw material The FPM and other fillers may be mixed individually or sequentially or simultaneously with a roll mixer, a propeller mixer, a kneader mixer, a twin-screw melt mixer, and other mixers. Also,
At this time, it is desirable to install a temperature controller to prevent heat generation due to friction. Further, when a roll mixer is used, it is preferable to carry out thin-threading as finishing mixing.

[0019]

In the lubricating rubber composition of the present invention, the fluorocarbon rubber constituting the rubber base material is mixed with the tetrafluoroethylene resin powder having the carbon material pierced on the surface thereof. The mixed state of the material and the tetrafluoroethylene resin is maintained.

Further, since spherical graphite is also compounded, the affinity with the rubber base material is exerted, and the kneading with the tetrafluoroethylene resin is made stronger.

[0021]

EXAMPLES The present invention will now be described in more detail by way of examples.

First, the FPM used in Examples and Comparative Examples
The basic composition is shown below.

The mixing ratios of the respective components are all% by weight, but the filling ratio is based on 100 parts by weight of the rubber base material.

(1) Basic compounding A = vinylidene fluoride / hexafluoropropylene copolymer FPM Technoflon F5350 manufactured by Montecatini Co. 100 parts by weight Stearic acid general industrial material 2 parts by weight Carbon MT 5 parts by weight Magnesium oxide general industrial material 3 Parts by weight Calcium hydroxide General industrial material 6 parts by weight (2) Basic compounding B = vinylidene fluoride / hexafluoropropylene copolymer FPM Showa Denko Viton A 100 parts by weight Stearic acid General industrial material 2 parts by weight Carbon MT 5 Parts by weight Magnesium oxide General industrial materials 15 parts by weight Diak No.3 General industrial materials 3 parts by weight (3) Basic compounding C = 4 Fluorinated ethylene / propylene copolymer FPM Asahi Glass Co., Ltd. Aflas 150 100 parts by weight Stearic acid general industrial materials 2 parts by weight Carbon MT 5 parts by weight Organic peroxide General industrial materials 1 part by weight TAIC General industrial materials 5 Parts by weight Lubricant (1) Graphite coprecipitated PTFE PTFE / GRP-1 This is obtained by coprecipitation with graphite having an average particle size of 6 μm after completion of polymerization by emulsion polymerization, coagulation and washing. (2) Dry powder with graphite PTFE PTFE / GRP-2 Fine powder obtained by coagulation and washing after completion of polymerization by emulsion polymerization was dry blended with graphite with an average particle size of 6 μm in a Henschel mixer. is there. (3) PTFE Asahi Glass Co., Ltd. PTFE Lubricant L169 (4) ETFE Asahi Glass Co., Ltd. Aflon COP Z8820 (5) Spherical graphite A Kanebo bellbell C2000 (6) Spherical graphite B Osaka Gas Co. mesocarbon beads MP280
0.

[Examples 1 to 7] First, roll intervals of 5 to 1
Wrap FPM (Technoflon) around a roll mixer adjusted to about 0 mm, mix inorganic filler, carbon, and vulcanizing agent in the proportions shown in the basic formulation A in order, and finally add PTFE in the proportions shown in Table 1. And other fillers were kneaded.

After that, the roll interval was adjusted to 1 mm and thin threading was performed 10 times. For the purpose of preventing frictional heat at this time, cooling water was constantly passed through the roll to keep the roll temperature at 60 degrees or less.

Next, the cooling water was stopped and steam was passed through the rolls to adjust the rubber temperature so that the rubber temperature was 70 degrees or more and 90 degrees or less.
The process was repeated and 10 kg of compounds were obtained.

For each compound, a die having a length of 300 mm, a width of 300 mm, and a thickness of 1 mm is used, and press molding is performed to obtain 1
Next vulcanization (170 ° C, 10 minutes, press pressure 35kg / cm ² )
Then, secondary vulcanization (free heating, 230 ° C., 16 hours) was performed, and the friction / wear characteristics and elastic body characteristics of the respective vulcanized sheets were determined.

Each test method is as follows.

(1) Friction and abrasion property test The obtained sheet was punched out with a φ17 × φ21 (mm) ring and bonded to a φ17 × φ21 × 10 (mm) aluminum alloy ring to give a friction test piece. Mating material is bearing steel (SUJ
2) A polished product was evaluated by a thrust type friction wear test. Test conditions are peripheral speed 1.0m / min, surface pressure 3.0kgf
/ Cm ² and time 100 h. The obtained results are shown in Table 2.

(2) Non-adhesive property test The contact angle of water in the obtained test piece was measured by a goniometer type contact angle measuring device, and it was judged that the larger the contact angle, the better the non-adhesiveness. The obtained results are shown in Table 2.

(3) Elastic body property test The obtained test piece is compliant with JIS-K6301,
The tensile strength, elongation and hardness (JIS-A) were investigated.
The obtained results are shown in Table 2.

Example 8 In Example 8, FPM was changed to Viton, and mixing, sheet molding, and vulcanization were performed in the proportions shown in Table 1 by the same method as in Examples 1 to 7. In addition, the test piece adjustment and test methods are also described in Examples 1 to 7.
The exact same method was used. The obtained results are shown in Table 2.

[Example 9] In Example 9, FPM was used as aflas, and mixing, sheet forming, and vulcanization were performed in the proportions shown in Table 1 by the same method as in Examples 1 to 7. In addition, the test piece adjustment and test methods are also described in Examples 1 to 7.
The exact same method was used. The obtained results are shown in Table 2.

[0035]

[Table 1]

[0036]

[Table 2]

Comparative Examples 1 to 6 In Comparative Examples 1 to 6, Table 1
Using a method exactly the same as in the example at the ratio shown in
Mixing, sheet molding, and vulcanization were performed. The test pieces were prepared and tested in the same manner as in the examples. The obtained results are shown in Table 2.

As is clear from Table 2, PPM is added to FPM.
In each of Comparative Examples 2 and 3 in which E was added, the friction coefficient was lower than that of the rubber base material, but the mechanical strength (particularly tensile strength) was significantly reduced and the wear resistance was also insufficient. Comparative Examples 5 and 6 in which coprecipitated PTFE and spheroidal graphite were used alone had a low friction coefficient, but the wear characteristics were not sufficiently improved.

However, in the examples in which the PTFE having the carbon material pierced on the surface and the spheroidal graphite were added, it was confirmed that the mechanical strength was not significantly decreased, the low friction coefficient was maintained, and the wear resistance was improved. Further, the physical properties of rubber as an FPM material were also sufficient.

[0040]

As described above, the lubricating rubber composition according to the present invention has sufficient rubber properties as an FPM material, but is also excellent in low friction coefficient and abrasion resistance. Therefore, the seal parts and the like can be used without grease and have excellent stability and reliability for a long period of time.

Therefore, it can be said that the significance of the present invention is extremely great.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example.

[Explanation of symbols]

 1 PTFE 2 Graphite 3 Rubber base material

Claims (4)

[Claims] 1. A lubricating rubber composition in which the first essential component is fluororubber, the second essential component is tetrafluoroethylene resin powder having a carbon material stuck on the surface thereof, and the third essential component is spherical graphite. 2. The lubricative rubber composition according to claim 1, wherein the second essential component is a tetrafluoroethylene resin powder having a carbon material pierced on its surface by coprecipitation with the carbon material after the completion of emulsion polymerization. 3. The second essential component is a tetrafluoroethylene resin powder in which the carbon material is pierced on the surface by dry-mixing the tetrafluoroethylene resin powder and the carbon material. Lubricating rubber composition. 4. The mixing ratio of the second essential component is in the range of 10 parts by weight or more and less than 140 parts by weight with respect to 100 parts by weight of the first essential component, and the third ratio is 100 parts by weight of the first essential component. The lubricating rubber composition according to claim 1, wherein the essential component is 5 parts by weight or more and less than 80 parts by weight.