JP2001090836A - Fluororesin sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluororesin sliding member with great strength, excellent abrasion resistance and a low coefficient of dynamic friction. SOLUTION: Aramid fiber 2 is dispersed in a base material 1 made of PTFE. Lubricant 3 is impregnated in an interface between the base material 1 and the aramid fiber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin sliding member used for a packing, a piston ring or the like which requires abrasion resistance.

[0002]

2. Description of the Related Art Sliding members used for packing and the like include:
Low friction resistance is required, and various materials have been used together with lubricating oils. Particularly, sliding members made of polytetrafluoroethylene (hereinafter referred to as “PTFE”) have excellent heat resistance and chemical resistance. Because of its low dynamic friction coefficient, it is often used as a dry sliding member that does not use lubricating oil. PTFE has excellent friction characteristics as described above, but has disadvantages in strength and abrasion resistance. For this reason, strength and wear resistance are improved by adding a filler such as resin powder, carbon, and aramid fiber to the PTFE, and when the aramid fiber is added, the improvement is achieved. It is known that the effect is particularly high.

[0003]

The use of the above-mentioned filler such as aramid fiber can improve the strength and abrasion resistance, but tends to increase the dynamic friction coefficient. For this reason, when a large amount of filler is blended, the aggressiveness of friction against the partner material increases, and depending on the material of the partner material,
There is a problem that the amount of wear of the counterpart material increases.

[0004] In view of the above-mentioned conventional problems, an object of the present invention is to provide a fluororesin sliding member having high strength, excellent wear resistance, and low dynamic friction coefficient.

[0005]

According to the present invention, there is provided a fluororesin sliding member for achieving the above object, in which a heat-resistant resin fiber is dispersed in a base material made of PTFE. The interface is characterized by being impregnated with a lubricant. According to the fluororesin sliding member having the above configuration, the strength and wear resistance can be improved by the heat-resistant resin fibers dispersed in PTFE, and the lubrication impregnated at the interface between the base material and the heat-resistant resin fibers can be achieved. The dynamic friction coefficient can be reduced by the agent. That is, since PTFE requires a high temperature state exceeding 300 ° C. for a long time during molding, it is difficult to mold in a state in which a lubricant is mixed, and because of water repellency and oil repellency, liquid lubrication after molding is difficult. It was also difficult to impregnate the agent, but when the heat-resistant resin fiber was dispersed in PTFE, the interface between the PTFE and the heat-resistant resin fiber, that is, the boundary between the heat-resistant resin fiber and the PTFE or the heat-resistant resin fiber The surface layer can be impregnated with and held by a liquid lubricant, and the lubricant reduces the coefficient of kinetic friction and obtains the knowledge that excellent properties as a sliding member can be obtained. The invention has been completed.

The heat-resistant resin fiber is preferably an aramid fiber (claim 2). In this case, the strength and abrasion resistance can be more effectively improved, and the aramid fiber has Due to the hydrophilicity and lipophilicity, the lubricant can be easily impregnated into the substrate deeper than the surface.

The fluororesin sliding member has a polytetrafluoroethylene ratio of 70 to 90% by weight, an aramid fiber ratio of 3 to 15% by weight, and a lubricant ratio of 1 to 15% by weight. It is preferable that there be (claim 3). If the proportion of PTFE in the entire sliding member is less than 70% by weight, it is difficult to mold it. If it exceeds 90% by weight, the amount of aramid fiber is reduced, and the strength and wear resistance of the aramid fiber are improved. The effect is reduced. If the ratio of the aramid fiber is less than 3% by weight, the effect of improving strength and abrasion resistance is small, and if it exceeds 15% by weight, it becomes difficult to form PTFE. Further, when the proportion of the lubricant is less than 1% by weight, the effect of reducing the dynamic friction coefficient is small,
If it exceeds 15% by weight, the effect of reducing the dynamic friction coefficient is saturated.

In the fluororesin sliding member, graphite or molybdenum disulfide may be added to the substrate itself. In this case, the graphite or molybdenum disulfide as a solid lubricant is used. Thereby, the wear resistance can be more effectively improved. In this case, the proportion of graphite or molybdenum disulfide in the entire sliding member is preferably 1 to 15% by weight (claim 5), whereby the resistance to the base material is not impaired. Abrasion can be more effectively improved. That is, if the proportion of the graphite or molybdenum disulfide is less than 1% by weight, the wear resistance cannot be effectively improved, and if it exceeds 15% by weight, it becomes difficult to form PTFE.

[0009]

Embodiments of the present invention will be described below in detail. FIG. 1 is a schematic diagram showing the internal structure of the fluororesin sliding member of the present invention. In this fluororesin sliding member, PTFE was used as a base material 1, aramid fibers 2 as heat-resistant resin fibers were dispersed therein, and an interface between the base material 1 and the aramid fibers 2 was impregnated with a lubricant 3. Things.

The ratio of the substrate 1 to the entire sliding member is 70 to 90% by weight. The substrate 1 itself has
As the solid lubricant 4, graphite or molybdenum disulfide is added. The ratio of the solid lubricant 4 to the entire sliding member is 1 to 15% by weight. Aramid fiber 2
Are uniformly dispersed inside the base material 1 with a part thereof being exposed on the surface of the base material 1. This aramid fiber 2
Has a BET specific surface area of 6 m ² / g and a fiber length of 5
Those having a thickness of 0 to 1000 μm and a thickness of 5 to 20 μm are preferably used. The ratio of the aramid fiber 2 to the entire sliding member is 3 to 15% by weight. Examples of the lubricant 3 include liquid paraffin, silicone oil, fluorine oil,
Examples thereof include mechanical oil, castor oil, and oleic acid, which can be used regardless of viscosity as long as they can be liquefied at least when impregnating the interface between the base material 1 and the heat-resistant resin fiber 2. .

According to the fluororesin sliding member, the substrate 1
By the aramid fibers 2 dispersed in the rubber, strength and abrasion resistance can be effectively increased. Further, the dynamic friction coefficient can be reduced by the lubricant 3 impregnated at the interface between the base material 1 and the aramid fiber 2. For this reason, although the strength and the wear resistance are enhanced, the aggressiveness of the friction to the partner material is low, and the wear amount of the partner material can be reduced. Further, since graphite and molybdenum disulfide are added to the base material 1 as the solid lubricant 4,
The wear resistance of the sliding member can be more effectively improved.

Further, since the aramid fiber 2 has hydrophilicity and lipophilicity, the interface with the substrate 1 can be easily impregnated with the lubricant 3. Further, since the lubricant 3 can be made to penetrate deep inside the substrate 1, a large amount of the lubricant 3 can be impregnated in the interface, and the lubricant 3 can be continuously absorbed from the surface of the substrate 1. And the effect of reducing the dynamic friction coefficient is stably exhibited over a long period of time.

Further, the fluororesin sliding member has a PTFE content of 70 to 90% by weight, an aramid fiber content of 3 to 15% by weight, and a lubricant content of 1 to 90% by weight.
Since 15% by weight and the ratio of the solid lubricant 4 are 1 to 15% by weight, good formability can be ensured, and the strength, the wear resistance improving effect, and the dynamic friction coefficient reducing effect are particularly excellent. . That is, when the proportion of PTFE is less than 70% by weight, the molding is difficult, and when it exceeds 90% by weight, the compounding amount of the aramid fiber 2 is reduced, and the effect of improving the strength and wear resistance by the aramid fiber 2 is reduced. Become smaller. When the ratio of the aramid fiber 2 is less than 3% by weight, the effect of improving strength and abrasion resistance is small, and is 15% by weight.
If it exceeds, molding of PTFE becomes difficult. Further, if the ratio of the lubricant 3 is less than 1% by weight, the effect of reducing the dynamic friction coefficient is small, and if it exceeds 15% by weight, the effect of reducing the dynamic friction coefficient is saturated. If the ratio of the solid lubricant 4 is less than 1% by weight, the effect of improving the wear resistance by the solid lubricant 4 is small, and if it exceeds 15% by weight, the molding of the base material 1 becomes difficult.

The fluororesin sliding member having the above structure is manufactured, for example, by the following manufacturing method. First, an aramid fiber 2 and a solid lubricant 4 are blended with PTFE as a base material 1, and a molded body is manufactured by a free baking method. At this time, the PTFE, the aramid fiber 2 and the solid lubricant 4 are uniformly mixed by a high-speed mixer, and the obtained mixed powder is put in a mold and pre-molded under the conditions of compression molding pressure of 50 to 100 MPa and room temperature. Preformed product at 360-380 ° C, 2
It is fired under firing conditions of up to 5 hours. Next, the molded body obtained as described above is cut into a desired shape as required, and then immersed in a liquid lubricant to impregnate the interface between the base material 1 and the aramid fiber 2 with the lubricant 3. Let it. At this time, the lubricant 3 can be easily and effectively impregnated with the aramid fibers 2 dispersed in the base material 1. If the impregnation of the lubricant 3 is performed under reduced pressure, the lubricant 3 can be impregnated more quickly.

The fluororesin sliding member may be one in which other heat-resistant resin fibers such as polyimide fibers are dispersed instead of the aramid fibers 2. In some cases, the solid lubricant 4 is not added.

[Example 1] Aramid fiber (manufactured by Nippon Aramid Co., Ltd .: trade name "Twaron 1097") is mixed with PTFE (manufactured by Daikin Industries, Ltd .: trade name "M-12") as a base material. A molded body is manufactured by a baking method, and the molded body is subjected to a cutting process to obtain a cylindrical body. The cylindrical body is immersed in liquid paraffin, which is a liquid lubricant, and flows into the interface between the base material and the aramid fiber. Impregnated with paraffin,
A fluororesin sliding member comprising 80% by weight of TFE, 15% by weight of aramid fiber and 5% by weight of liquid paraffin was produced.

Example 2 A cylindrical body obtained in the same manner as in Example 1 was immersed in silicon oil as a liquid lubricant, and the interface between the base material and the aramid fiber was impregnated with silicon oil. , 80% by weight of PTFE, 15% by weight of aramid fiber, and 5% by weight of silicone oil to prepare a fluororesin sliding member.

Example 3 The same PTFE and aramid fibers as in Example 1 were added to graphite (LONZ) as a solid lubricant.
A product name “KS-75” manufactured by Company A) is blended, a molded body is manufactured by a free baking method, and the molded body is subjected to a cutting process to obtain a cylindrical body. Immersed in a certain silicon oil, impregnated with silicon oil at the interface between the base material and the aramid fiber, PTFE 80% by weight, aramid fiber 10% by weight, graphite 5% by weight,
A fluororesin sliding member made of 5% by weight of silicone oil was produced.

[Comparative Example 1] As Comparative Example 1, a cylinder obtained in the same manner as in Example 1 was impregnated with a lubricant without impregnating with PT.
A fluororesin sliding member comprising 85% by weight of FE and 15% by weight of aramid fiber was produced.

Comparative Example 2 As Comparative Example 2, a cylindrical body obtained in the same manner as in Example 3 was not impregnated with a lubricant,
A fluororesin sliding member comprising 80% by weight of FE, 15% by weight of aramid fiber and 5% by weight of graphite was produced.

Comparative Example 3 As Comparative Example 3, the same PTFE as in Example 1 was mixed with an aromatic polyester powder.
A molded body is manufactured by a free baking method, and the molded body is subjected to a cutting process to obtain 80% by weight of PTFE, 15% by weight of an aromatic polyester powder, and 5% by weight of a liquid paraffin.
A fluororesin sliding member made of a cylindrical body was produced.

[Comparative Example 4] As Comparative Example 4, a cylinder obtained in the same manner as in Example 1 was immersed in liquid paraffin as a liquid lubricant and flowed to the interface between the base material and the aramid fiber. Paraffin was impregnated to prepare a fluororesin sliding member comprising 75% by weight of PTFE, 20% by weight of aramid fiber, and 5% by weight of liquid paraffin.

A sliding test was performed on the above Examples 1 to 3 and Comparative Examples 1 to 3 using a thrust type friction and wear tester. In the above-mentioned sliding test, the end surface of the cylindrical counterpart material is brought into contact with the end surface of the cylindrical fluororesin sliding member by a thrust-type friction and wear tester, and both are rotated relative to each other. Weight loss was measured. The sliding area is 2 cm ² . The test conditions were as follows: the test surface pressure P was 0.5 MPa and 1.0 MPa in the atmosphere at room temperature;
Is set to 1.0 m / s, and PV = 0.5, 1.0 MPa
M / s. The test time was 20 hours, the wear volume after the test was determined, and the specific wear amount {= wear volume / (load / friction distance)} was measured. The dynamic friction coefficient (= frictional resistance during sliding / surface pressure) during this time was measured. SUS304 having a surface roughness of 6.3 s or less was used as a mating material.

FIG. 2 is a graph comparing the change over time in the dynamic friction coefficient between Example 1 and Comparative Example 1. According to the figure, in Example 1 in which the interface between the base material and the aramid fiber was impregnated with 5% by weight of liquid paraffin, PTFE having a small friction coefficient was 85%.
%, The dynamic friction coefficient is lower than that of Comparative Example 1 in which liquid paraffin was not impregnated. FIG. 3 is a comparison of the change over time in the dynamic friction coefficient between Example 2 and Comparative Example 1. According to the figure, graphite as a solid lubricant was not added to the base material, but 5% by weight of silicone oil was added to the interface between the base material and the aramid fiber.
In the impregnated Example 2, the graphite was added to the substrate, but the dynamic friction coefficient was lower than that of Comparative Example 2 in which the interface between the substrate and the aramid fiber was not impregnated with the silicone oil. I understand. FIG. 4 shows Example 3 and Comparative Example 2.
5 is a comparison of the change with time of the dynamic friction coefficient with the above. As shown in the figure, in both Example 3 and Comparative Example 2, graphite as a solid lubricant was added to the base material, but the interface between the base material and the aramid fiber was impregnated with 5% by weight of silicone oil. It can be seen that the dynamic friction coefficient of Example 3 is lower than that of Comparative Example 2 not impregnated with silicone oil.

As shown in FIGS. 1 to 3, Examples 2 and 3 in which the interface between the base material and the aramid fiber was impregnated with a lubricant.
It can be seen that at the same time, at the same time as the dynamic friction coefficient is lowered, the fluctuation range of the dynamic friction coefficient is continuously greatly reduced from the time of the initial sliding. This indicates that in Examples 1 to 3, the lubricant was effectively held at the interface between the base material and the aramid fiber, and gradually bleed out. Furthermore, when Examples 1 and 2 and Example 3 are compared,
It can be seen that the dynamic friction coefficient of Example 3 in which graphite as a solid lubricant was added to the base material was more effective than Examples 1 and 2 in which graphite was not added. Next, Table 1 shows the measurement results of the specific wear amount.

[0026]

[Table 1]

In Table 1, Examples 1 to 3 and Comparative Examples 1 to
In comparison with No. 3, it can be seen that the specific wear amount of each of Examples 1 to 3 was smaller than that of Comparative Examples 1 to 3, and the wear resistance characteristics were clearly improved. This is shown in FIGS.
In view of the results, it is shown that the addition of the aramid fiber can effectively retain the lubricant and can significantly improve the friction characteristics and the wear characteristics. Further, in Table 1, it can be seen that the specific wear amount of Comparative Example 3 is higher than that of Example 1. Thus, it is clear that aramid fibers are more suitable than aromatic polyester powder as a filler for improving friction and wear characteristics. Furthermore, as can be seen from the specific wear amount of Comparative Example 4 in Table 1, when the aramid fiber content exceeds 20% by weight, the difficulty of forming PTFE and the hardness of the aramid fiber are combined, and the specific wear amount is less than that of the example. Greatly exceed. In the above example, graphite was used as the solid lubricant, but the same effect was confirmed when molybdenum disulfide was used.

[0028]

As described above, according to the fluororesin sliding member of the first aspect, the interface between the PTFE and the heat-resistant resin fibers dispersed therein is impregnated with the lubricant. Although the strength and wear resistance are improved by the heat-resistant resin fiber, the dynamic friction coefficient can be reduced. For this reason, the amount of wear of the mating member of friction can be reduced, and maintenance-free of the sliding portion can be achieved.

According to the fluororesin sliding member of the second aspect, since the heat-resistant resin fiber is an aramid fiber, strength and wear resistance can be more effectively improved. Further, the hydrophilicity and lipophilicity of the aramid fiber allow the lubricant to be easily impregnated into the base material, and the lubricant can be deeply impregnated into the base material. And a low dynamic friction coefficient can be stably maintained over a long period of time.

According to the third aspect of the present invention, the proportion of PTFE is 70 to 90% by weight, the proportion of aramid fiber is 3 to 15% by weight, and the proportion of lubricant is 1 to 15% by weight. Therefore, good moldability can be ensured, and the effect of improving the strength and wear resistance and the effect of reducing the dynamic friction coefficient are particularly excellent.

According to the fluororesin sliding member according to the fourth aspect, since the solid lubricant graphite or molybdenum disulfide is added to the base material itself, the wear resistance can be more effectively improved. it can.

According to the fluororesin sliding member according to the fifth aspect, the proportion of graphite or molybdenum disulfide in the whole sliding member is 1 to 15% by weight, so that the resistance to the base material is not impaired without impairing the formability. Abrasion can be more effectively improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an internal structure of a fluororesin sliding member of the present invention.

FIG. 2 is a graph showing dynamic friction coefficient evaluation test results of Example 1 and Comparative Example 1.

FIG. 3 is a graph showing dynamic friction coefficient evaluation test results of Example 2 and Comparative Example 1.

FIG. 4 is a graph showing dynamic friction coefficient evaluation test results of Example 3 and Comparative Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Aramid fiber (heat resistant resin fiber) 3 Lubricant 4 Solid lubricant

Claims (5)

[Claims] 1. A fluororesin sliding, wherein a heat-resistant resin fiber is dispersed in a base material made of polytetrafluoroethylene, and an interface between the base material and the heat-resistant resin fiber is impregnated with a lubricant. Element. 2. The fluororesin sliding member according to claim 1, wherein said heat-resistant resin fibers are aramid fibers. 3. The sliding member has a polytetrafluoroethylene ratio of 70 to 90% by weight, an aramid fiber ratio of 3 to 15% by weight, and a lubricant ratio of 1 to 15% by weight. The fluororesin sliding member according to the above. 4. The sliding member according to claim 1, wherein graphite or molybdenum disulfide is added to the base material itself. 5. A sliding member according to claim 4, wherein the proportion of graphite or molybdenum disulfide is 1 to 15% by weight.
The fluororesin sliding member according to the above.