JPH02206638A - Lubricating resin composition - Google Patents

Abstract

PURPOSE:To obtain lubricating resin composition suitable for electrical apparatus part or machine component, etc., having especially improved sliding properties in high speed region and stable sliding properties for a long period of time by compounding fluorine-based resin with polyimide resin particle. CONSTITUTION:(A) 30-95wt.% fluorine-based resin preferably having 10000-50000 averaged molecular weight (e.g. tetrafluoroethylene/hexafluoropropylene copolymer) is compounded with (B) 5-70wt.%, preferably 10-40wt.% spherical particles having <=100mum, preferably 5-50mum averaged particle diameter composed of polyimide resin having repeating unit of imide bonding expressed by formula I, preferably aromatic polyimide expressed by formula II (Ar1 is expressed by formula III or formula IV; Ar2 is expressed by formula V or formula VI, etc.) and polyimide resin obtained by heat-curing of bismaleimide expressed by formula VII (Ar3 is expressed by formula V or formula VI, etc.) with hardener such as diamine to afford the aimed lubricating resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a lubricating resin composition. For more details,
The present invention relates to a lubricating resin composition with excellent sliding properties suitable for electrical equipment parts, mechanical parts, etc.

(Prior art and its problems) In recent years, with the need to reduce the weight of equipment, synthetic resin products have come to be used in many mechanical parts instead of metal products, such as sliding members such as bearings and slide bases. Synthetic resin products are also beginning to be used in

Conventionally, fluororesins with excellent sliding properties, particularly tetrafluoroethylene resins, have been mainly used as such sliding members. However, although such resins satisfy the required sliding properties when used at low speeds and low loads, they suffer from significant plastic deformation (creep) at high speeds and medium to high loads, making it difficult to maintain long-term stability. It has the disadvantage that sliding properties cannot be obtained and a large amount of abrasion powder is generated during sliding.

For this reason, methods of reinforcing the material by adding various fillers have been attempted so as to provide sliding properties, particularly wear resistance, even under more severe conditions. For example, a method of adding glass fiber, carbon fiber or aromatic polyamide fiber (
For example, methods of adding polyimide resin or polyamideimide resin (Japanese Patent Publication No. 47-31097) are already known, but these methods do not improve wear resistance. Although improvements were seen in this respect, the frictional properties were not fully satisfactory because they did not take full advantage of the characteristics of the fluororesin and also had the disadvantage of damaging the mating material.

Furthermore, a method of adding meta-oriented aromatic polyamide powder as the aromatic polyamide is already known. Tokukai 1986
According to Japanese Patent No. 238351, it is disclosed that high sliding characteristics can be obtained by this method without damaging the mating material.

However, in the method using meta-oriented aromatic polyamide particles, it has been found that during sliding in a high-speed region, so-called abnormal wear occurs in which the amount of wear increases rapidly at a certain period. In other words, when sliding at high speeds, meta-oriented aromatic polyamides cannot exhibit sufficient heat resistance, and as a result of their inherent lack of hardness as a solid lubricant, when used at high speeds, the It is presumed that abnormal wear occurs from this.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and has excellent sliding characteristics without damaging the mating material, especially when sliding in a high-speed region. Moreover, it is an object of the present invention to provide a lubricating resin composition that does not cause abnormalities due to long-term use.

(Means for Solving the Problems) That is, the present invention is a lubricating resin composition characterized by comprising 30 to 95% by weight of fluorine thread resin and 5 to 70% by weight of polyimide resin particles.

The fluororesin used in the present invention refers to a resin in which hydrogen in polyolefins has been replaced with fluorine. Specifically, it refers to a polytetrafluoroethylene homopolymer, tetrafluoroethylene and hexafluoropropylene, ethylene, Copolymers with fluoroalkyl vinyl ethers, etc.
Examples include, but are not limited to, one or more types of polyvinylidene fluoride, copolymers of vinylidene fluoride and tetrafluoroethylene, hexafluoropropylene, ethylene, perfluoroalkyl vinyl ether, etc. .

The average molecular weight of this fluororesin is 1ooo.

50,000 is usually preferably used in the present invention.

In the present invention, it is extremely important that polyimide resin particles are used. That is, in order to obtain high sliding properties in a high-speed range and stable sliding properties for a long time, the solid lubricant itself needs to have high heat resistance. Further, in order to improve the wear characteristics without damaging the mating material, appropriate hardness is required.

The polyimide resin used in the present invention may be imide bonds formed by dehydration condensation and ring closure from a tetracarboxylic acid or a derivative thereof and a diamine compound. The formula below (
A polyimide resin obtained by heating and curing bismaleimide shown in 2) with a curing agent such as a diamine has particularly excellent heat resistance, chemical resistance, and mechanical properties, and is the most preferably used polyimide resin in the present invention.

- In the present invention, other structures in the repeating unit are not particularly limited, and for example, a combination of an aliphatic diamine and an aliphatic tetracarboxylic acid, an alicyclic diamine and a tetracarboxylic acid. Combinations of acids, combinations with aromatic diamines and tetracarboxylic acids, copolymers of these diamines and tetracarboxylic acids, and polyimides generally referred to collectively as bismaleimide, etc. -0-1CO--CH2Sow- represents one or more types selected from ).

-GO--CHZ--SOz-)

These aromatic polyimides can be converted into - by reaction with the corresponding aromatic diamine and aromatic tetracarboxylic acid anhydride.
After passing through polyamic acid, the ring is closed by direct heat treatment or chemical dehydration treatment, and the corresponding aromatic polyimide is obtained. In addition, the imide bond represented by formula (2) can be formed by heating the bismaleimide represented by formula (2) together with a curing agent such as an aromatic diamine, or by adding a peroxide and curing by heating. It can be made of polyimide resin with

Particles can be obtained from such a polyimide resin by, for example, pulverizing the resin obtained by the above-mentioned method using a commonly used mechanical pulverizing means such as a ball mill or a jet mill. Further, for example, particles which are insolubilized and precipitated by heat treatment in the polymerization stage can be obtained as they are, or by pulverizing and classifying as necessary.

In the present invention, the means for obtaining particles is not particularly limited.

The particle size (representing the average particle size, hereinafter simply referred to as particle size) of the polyimide resin particles used in the present invention is:
Although it varies somewhat depending on the material of the mating material when used as a sliding material, a material of 100 μm or less is usually preferably used. In order to obtain particularly high sliding properties, it is preferable to use particles having a particle size in the range of 5 to 50 μm.

High sliding properties can be obtained regardless of the shape of the particles, such as spherical, scale-shaped, rod-shaped, etc., but in order to obtain particularly high sliding properties, it is desirable that the particles be spherical.

In the lubricating resin composition of the present invention, the mixing ratio of the above-mentioned fluororesin and polyimide resin particles is 1, which is an important factor. It is necessary to.

If the amount of polyimide resin particles is less than 5% by weight, the effect will be small and the amount of wear will be large, and if it exceeds 70% by weight, the hard polyimide resin particles themselves will act as a base material and the coefficient of friction will increase, which is undesirable. . The most suitable mixing ratio of polyimide resin particles is 10 to 40% by weight.

In order to mix the fluororesin and polyimide resin particles in the above-mentioned proportions in order to obtain the lubricating resin composition of the present invention, conventionally known methods may be used. For example, fluororesin powder and polyimide resin particles may be mixed using a mixer such as a Henschel mixer, a ball mill, or a tumbler mixer, or when using a meltable fluororesin, the powders may be mixed together and then melt-mixed. It is also possible to adopt a method in which the fluororesin is supplied to a highly efficient injection molding machine or extrusion molding machine, or the fluororesin is melted and mixed in advance using a heated roller, a Banbury mixer, or the like.

The method of molding the composition of the present invention into sliding materials, etc. is not particularly limited, but injection molding can usually be applied when a meltable fluororesin is used. Also, so-called compression molding is employed in which the mixed powder is first shaped by compressing it and then molded under heat and pressure. In some cases, extrusion molding is also possible, and the molding method may be appropriately selected depending on the purpose of use.

In addition to the fluororesin and polyimide resin particles, the lubricating resin composition of the present invention may also contain additives that can be widely incorporated into synthetic resins, as appropriate, as long as they do not reduce the properties of the lubricating resin composition. I can do it. Examples of such additives include, but are not limited to, mold release agents, flame retardants, weather resistance improvers, etc., and conventionally known and publicly used solid or liquid lubricants are used in combination. Of course, this is possible, and graphite, fluorinated graphite,
Talc, boron nitride, silicone resin or oil, and other industrial lubricants can also be selected and used as appropriate depending on the purpose of use. In either case, it is of course possible to modify the intermediate or final product to improve its properties by chemical or physical treatment, as long as the lubricity of the lubricating resin composition of the present invention is not impaired.

(Function) The lubricating resin composition of the present invention has a small coefficient of friction, even in high-speed friction, as the polyimide resin, which has excellent heat resistance and mechanical properties, is finely dispersed to form a sliding contact surface. Stable sliding characteristics can be obtained, and at the same time, the fluororesin of the base material is reinforced, resulting in low wear and long-term stable sliding characteristics.

(Examples) Hereinafter, the present invention will be explained in more detail and concretely using Examples.

Evaluation of friction and wear properties〉 Friction coefficient: Surface pressure of 10 kg using a lead powder type friction and wear tester
/crm”, linear velocity 60cm/sec, 50 hours, mating material 3
Measured at 45C without oil.

Wear coefficient: Surface pressure 2Kg/C by lead dust type friction and wear tester
m! , linear velocity 60 cm/sec, 50 hours, mating material 545C
Measured without lubrication.

Reference Example 1 According to Japanese Patent Publication No. 36-10999, 51 N-methyl-2-pyrrolidone was mixed with 64 gr of lithium chloride and 4.
After dissolving 300g of 4'-diaminodiphenyl ether, it was cooled to 0°C. Next, 327 gr of pyromellitic dianhydride was added in powder form to carry out polycondensation so that the temperature in the system did not rise above 10°C. Next, the resulting polyamic acid solution was cast into a flat-bottomed vat and heated to 180°C, and further heated to 270°C to perform solvent removal and dehydration and ring closure to obtain a polyimide. Then,
The obtained flat polyimide was roughly crushed, then crushed using a jet mill type crusher, and then classified to have an average particle size of 4.
Polyimide particles of 6 μm and 21 μm were obtained.

Reference Example 2 Using a system in which calcium chloride was added to N-methyl-2-pyrrolidone as a solvent, polymetaphenylene isophthalamide was polymerized by a known method, and then the polymerization dope was placed in a Henschel mixer with water and stirred for 30 minutes. Shredded. This Henschel mixer is equipped with a vertical blade at a position where the distance from the vessel wall is 511II11. After the grinding operation was completed, the contents were taken out, the polymer particles were washed with water, and then dried. The obtained dry particles were placed in a Wiley type pulverizer and pulverized, and classified with a vibrating sieve to obtain polymetaphenylene isophthalamide particles having an average particle size of 78 μm.

Examples 1 to 5 Fluorine resin powder (manufactured by Mitsui Fluorochemical Co., Ltd.; Teflon? AJ) and polyimide resin particles obtained in Reference Example 1 were
Mix in a ball mill in the proportions shown in Table 1, dry the resulting mixed powder at 140°C,
III11 Loaded into a mold for forming a plate material with a thickness of 5 sm,
Consolidation was carried out at room temperature under a pressure of 1000 Kgf/cmz. The cough compacted body was then fired at 320'CX for 30 minutes, at 350°C for 1.5 hours, and at 330°C for 45 minutes under normal pressure to obtain a molded material.

A test piece was cut out from the molded material, and its friction and abrasion properties were evaluated according to the test method described above. The measurement results are shown in Table 1.

Comparative Example 1 From the fluororesin used in Examples 1 to 5 and the polymetaphenylene isophthalamide particles obtained in Reference Example 2,
Molded bodies were manufactured in the same manner as in the examples and tested and evaluated. The results are listed in Table 1.

Comparative Example 2 A test piece was cut out from a single fluororesin product (polytetrafluoroethylene) and evaluated for friction and wear under the same conditions as in this example. The results are listed in Table 1, but abnormal wear occurred within a few hours and the evaluation was abandoned midway. As is clear from these results, it was confirmed that the molded article made of the resin composition of the present invention had extremely excellent sliding properties.

(The following is a blank space) (Effects of the invention) As is clear from the above explanation and examples, by blending polyimide resin particles with fluororesin,
In particular, the sliding properties in the high-speed range are significantly improved, and stable sliding properties can be obtained for a long time.

As a result, it has become possible to use resin for sliding materials such as bearings in the high-speed range, which has been considered difficult in the past, and this has great effects in terms of weight reduction and economic efficiency.

Claims (1)

[Claims] Fluorine resin 30-95% by weight and polyimide resin particles 5
-70% by weight of a lubricating resin composition