JPS5818940B2 - Phenolic resin composition for sliding materials - Google Patents

Description

[Detailed description of the invention] The present invention relates to a resin composition for sliding materials.

Sliding resins such as phenol resins, epoxy resins, amine resins, cypolyimide resins, polyamideimide resins, and aralkyl ether resins have excellent electrical and mechanical properties, and also have excellent friction properties as sliding materials. is also excellent.

However, using these sliding resins alone has the drawback of high wear.

As a means for improving this, a method is known in which a suitable filler such as natural or artificial graphite, carbon fiber, glass fiber, asbestos fiber, metal oxide, etc. is selected and added.

However, the above-mentioned known or well-known means have limitations in improving wear resistance and lowering the coefficient of friction in an atmosphere such as a vacuum or high temperature, and are not sufficient for use as a sliding material.

For example, natural graphite has excellent self-lubricating properties,
This is thought to be due to the layered structure of graphite.

However, if this product is used in a vacuum or at high temperatures, abnormal wear occurs, so a small amount of moisture is required in the usage atmosphere.

For this reason, there is a limit to the ability to slide without lubrication in a moisture-free vacuum or high-temperature atmosphere.

In other words, mixing ordinary natural graphite such as scaly graphite, earthy graphite, etc. or artificial graphite powder as a filler with sliding resin does not provide sufficient wear resistance, and addition of glass fiber does not affect the mating material. This limits its use as a sliding material.

Furthermore, carbon fiber is expensive and harder than ordinary graphite or carbon, so depending on the conditions of use, it has the disadvantage of damaging the surface of soft metals such as aluminum.

Furthermore, sliding materials using the above-mentioned fillers do not have sufficient wear resistance at high temperatures (and have not yet been able to lower the coefficient of friction).

As a result of various studies, the present inventors have found that adding hydrated graphite to the sliding resin is an extremely effective means of obtaining excellent wear resistance and a low coefficient of friction even in atmospheres such as vacuum and high temperature conditions. I found out.

The present invention relates to a phenolic resin composition for sliding materials, which is made by mixing 3 to 50% by weight of hydrated graphite obtained by treating graphite with an inorganic acid system and washing it with water.

In the present invention, the sliding resin contained in the phenolic resin composition for sliding materials (hereinafter referred to as the resin composition for sliding materials) is a known phenolic resin (phenol, cresol, xylenol, alkylphenol, etc.) made by condensing formaldehyde. Resin obtained) is used.

In the present invention, the hydrous graphite used is one obtained by a normal method. For example, natural scale graphite is treated with a mixed acid of concentrated sulfuric acid and concentrated nitric acid, dehydrated in water, and hydroxylated as necessary. Neutralize the excess acid and the acid adsorbed on the graphite surface with an ammonium aqueous solution.
Hydrous graphite can be obtained by drying at 00°C.

As the graphite, normal natural graphite such as scaly graphite, earthy graphite, etc., or artificial graphite can be used, and the acid treatment system for graphite includes fuming nitric acid, concentrated sulfuric acid-potassium permanganate, concentrated sulfuric acid-potassium chlorate, Inorganic acid systems such as concentrated sulfuric acid-potassium dichromate and concentrated sulfuric acid-ammonium persulfate can be used.

Furthermore, the shape of the hydrated graphite should be adjusted to a size of 1 to 100 microns, especially 10 microns, in consideration of uniform mixing properties and improved sliding properties.
~50 microns is preferred.

If it is too large, problems will arise in uniform mixing properties and moldability of the composition, making it difficult to obtain a dense molded product without voids.

FIG. 1 shows an example of the weight loss rate due to heating of hydrated graphite obtained by the above method.

In addition to the sliding resin and hydrated graphite, various additives such as pigments, antistatic agents, and other carbon fibers and glass fibers can be added to the resin composition for sliding materials according to the present invention, if necessary. .

Furthermore, there is no particular limitation on the means for mixing these ingredients (for example, they can be mixed simultaneously in powder form, and it is also possible to mix them at the time of pulverizing the raw materials).

The sliding resin composition of the present invention can be molded by various molding methods, and for example, ordinary molding methods such as compression molding, transfer molding, injection molding, etc. can be applied depending on the properties of the sliding material.

Furthermore, ordinary molding methods in which glass fiber, asbestos, glass mat, etc. are impregnated and fired are also applicable.

In the present invention, hydrated graphite is added in an amount of 3 to 50% by weight based on the resin composition for sliding materials.

If the amount added is less than 3% by weight, the effect of adding hydrated graphite is small, so the variation in properties becomes large (or 50% by weight).
If it exceeds this value, the mixability and moldability of the material will deteriorate significantly, and the strength of the material will decrease.

The present invention will be explained below with reference to Examples.

. In addition, in the following examples and comparative examples, % indicates weight percent.

Example 1 Natural graphite 1501 from the Soviet Union, which has a fixed carbon content of 98%, ash content of 1%, and volatile content of 1% and has a peak at 1200 mesh, was mixed with 400 g of concentrated sulfuric acid (95%) and 200 g of nitric acid (60-62%).
After being immersed in the mixed acid solution of f for 2 hours at room temperature, the pH was 6.
I washed it with water so that it was 5.

This was suction-filtered to obtain wet graphite with a water absorption of 30%.

Next, it was dried in a dryer at 150° C. for 1 hour to obtain hydrated graphite.

30% hydrated graphite thus obtained, novolac type phenol formaldehyde powder resin (containing 12% hexamethylenetetramine), 35% asbestos (manufactured by Mitsubishi Gas Chemical KK, trade name SMP107A), asbestos (manufactured by Johns Manville, Product name Class 6D asbestos fiber) 33%,
2% of magnesium stearate (manufactured by NOF ■, trade name Nirasan Magnesium Stearate) was uniformly premixed using a high-speed mixer.

Thereafter, 6% methanol (externally divided) was added, and after kneading under pressure with a pressure kneader, the volatile content and fluidity were adjusted with a heating roll to obtain a resin composition for sliding materials.

Next, add the resin composition for sliding material to 70mm x 100im.
It was compression molded into a 5x5 plate, fired at 16'0°C for 14 hours, and then slowly cooled.

The molded product was used in a JIS type constant speed friction test.

The test results are shown in FIGS. 2 and 3.

Comparative Example 1 The blending ratio was the same as in Example 1, and natural scaly graphite (manufactured by Nippon Graphite Industries ■, trade name CB-150) was used instead of hydrous graphite.
The other operations were the same as in Example 1.

Example 2 Same as those used in Example 1: 30% hydrated graphite, 35% novolac type phenol formaldehyde powder resin, 25% asbestos, 2% magnesium stearate, and carbon fiber (manufactured by Kureha Kagaku KK, trade name Kureha Carbon Fiber M2O2). ) 8% were uniformly mixed using a high-speed mixer.

Thereafter, 7% (external) methanol was added, and after kneading under pressure with a pressure kneader, the volatile content and fluidity were adjusted with a heating roll to obtain a resin composition for sliding materials.

Next, apply this resin composition for sliding materials to 7 mm x 110 mm x 5
It was compression molded into a plate of mm in size, baked at 160°C for 14 hours, and then slowly cooled.

The molded product was used in a JIS type constant speed friction test.

The test results are shown in FIGS. 2 and 3.

Comparative Example 2 The blending ratio was the same as in Example 2, and natural scale graphite (manufactured by Nippon Graphite Industries KK, trade name CB-150) was used instead of hydrous graphite.
), and the other operations were the same as in Example 2.

In addition, JIS type constant speed friction test load: 10 kg/cA,
The test was carried out at a near speed of 85 m/sec using FC-25 pearlite as the mating material.

From the above results, composite materials made by adding hydrated graphite to phenolic resin have better sliding surfaces in high-temperature regions than composite materials made by adding natural scale graphite, carbon fiber, etc. (provided that hydrated graphite is not added). The coefficient of friction in a state with little moisture is extremely small and stable, and the wear rate is also significantly reduced, resulting in a marked improvement in sliding properties.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the treatment temperature of hydrous graphite and weight reduction rate, Figure 2 is a graph showing the relationship between disk surface temperature and friction coefficient, and Figure 3 is a graph showing the relationship between disk surface temperature and wear rate. It is.

Claims (1)

[Claims] 1. A diphenol resin composition for sliding materials, which is made by mixing 3 to 50% by weight of hydrated graphite obtained by treating graphite with an inorganic acid system and washing it with water.