JPH07731B2 - Wet friction material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wet friction material such as clutch fading in oil.

[Conventional technology]

In recent years, in the automobile industry, from the viewpoint of energy saving, weight reduction and high efficiency of various parts used have been promoted. Also in wet type friction materials, by improving the friction coefficient and increasing the energy absorption capacity per unit area, the number of clutch fadings has been reduced, and the size and weight have been reduced. However, the conventional wet friction material is inferior in friction coefficient and energy absorption ability, and there is a problem that the friction coefficient is lowered and the friction material itself is broken particularly when used for a long time.

[Problems to be solved by the invention]

In view of the above circumstances, the present inventors have obtained a wet friction material having excellent performance, particularly a high and stable friction coefficient, a high energy absorption capacity, and a stable friction characteristic even during long-term use. As a result of earnest research on the wet friction material, the present invention has been achieved.

[Means for solving problems]

That is, the wet friction material of the present invention has an oxirane oxygen concentration of 10
By using as a binder a phenolic resin modified with epoxidized polybutadiene that is ~ 15% by weight,
The above problems were solved.

[Function] The phenolic resin used as the main component of the binder in the present invention is a compound represented by the general formula (I) obtained by reacting phenols and aldehydes with an alkali catalyst.
Is a resol type phenolic resin.

Here, R is H or an alkyl group or an allyl group, and R'is-
Represents CH ₂ OH or hydrogen, m and n are each an integer of 0 to 10, and typical phenols include phenol, cresol, xylyl, butylphenol, etc., which are used in combination of two or more of them. It is also good. Formaldehyde, acetylaldehyde, furfural and the like can be used as the aldehydes, and alkali metal, alkaline earth hydroxides and amines can be used as the alkali catalyst. It is desirable that the resolization reaction is carried out at a molar ratio of phenols / aldehydes of 1 / 1.0 to 3.0, and the reaction temperature is usually 50-100 ° C.

The epoxidized polybutadiene used in the present invention is an epoxidized polybutadiene represented by the general formula (II) in which an epoxy group having an oxirane oxygen concentration of 10 to 15% by weight is introduced by reacting a polybutadiene polymer with a peroxide. Is.

When the oxirane oxygen concentration is less than 10% by weight, the reactivity of the phenol resin is poor and good heat resistance cannot be obtained. Further, when the oxirane oxygen concentration is higher than 15% by weight, the synthesis is difficult and it cannot be industrially used.

The total number of x, y and z is 20-40. The epoxidation of polybutadiene can be carried out in a manner similar to the epoxidation of natural oil. As the peroxide, peracetic acid, hydrogen peroxide or the like is used, and the reaction is carried out by sequentially adding it to polybutadiene.

The phenolic resin modified with this epoxidized polybutadiene has a heat resistance and a polybutadiene which the phenolic resin has by cross-linking the terminal methylol group of the phenolic resin and the epoxy group of the epoxidized polybutadiene during curing. It is presumed that a rubber material having a high and stable friction coefficient and an excellent energy absorbing ability can be obtained by exhibiting an alternating effect with the rubber elasticity of.

The mixing ratio of epoxidized polybutadiene and phenolic resin is epoxidized polybutadiene / phenolic resin =
It can be used in the range of 5/95 to 70/30 parts by weight, preferably epoxidized polybutadiene / phenolic resin = 10/90 to 5
It is in the range of 0/50 parts by weight.

The modification of the phenolic resin with the epoxidized polybutadiene may be carried out by preliminarily heating and reacting before the friction material is manufactured, or both may be simply mixed to prepare a resin solution, which is impregnated into the base material and then heat-treated. May be reacted.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 Production of Phenolic Resin Intermediate To 100 g of phenol, 103 g of 37% formalin aqueous solution was added, and 20
After adjusting the pH to 9.0 with 100% aqueous ammonia, the mixture was reacted at 100 ° C. for 1 hour, and immediately after the reaction was completed, dehydration was started under a reduced pressure of 80 mmHg to maintain the temperature of the reaction system at 55 ° C. The end point of dehydration is when the amount of dehydration reaches 60 g, and after this dehydration, 60 g of methanol is added to adjust the nonvolatile content to 65%,
An intermediate was obtained. At this time, the weight average molecular weight is 800 and the viscosity is 3
It was 00 cps.

Production of epoxidized polybutadiene-modified phenolic resin To 100 g of the above-mentioned phenolic resin intermediate, epoxidized polybutadiene 16.3 g was added and reacted at 80 ° C. for 2 hours. After completion of the reaction, acetone 16.3 g and methanol 30 g were added, and the nonvolatile content was 50%.
162.6 g of a resin solution of was obtained. The epoxidized polybutadiene used here has a weight average molecular weight of 1,000 and an epoxy equivalent of 15
0, oxirane oxygen concentration was 10% by weight.

Manufacture of Friction Material A link-shaped base material was prepared by punching from a paper-like sheet obtained by paper-making by a usual method from a dispersion liquid in which linter pulp and a filler are dispersed in water. Here, the filler is an inorganic compound such as barium sulfate or calcium carbonate, a fiber such as grafida aramid, or a powder of a cured resin.

66.7 parts of methanol was added to 100 parts by weight of epoxidized polybutadiene-modified phenolic resin to adjust the nonvolatile content to 30%, the above base material was impregnated with this diluted solution, and air-dried at room temperature for 30 minutes, then in a dryer at 200 ° C. And heat treated for 20 minutes.
At this time, the resin solid component adhesion amount to the substrate was 35%. After fitting this ring-shaped sheet to the core metal coated with phenol resin adhesive, press it at 170 ℃, 100kg / c
It was molded for m ^{2 for} 5 minutes to obtain the intended friction material.

The performance of the friction material was evaluated by a short-time friction test using a SAE # 2 in-oil friction tester.

The test conditions are shown in Table-1.

Table-1: Conditions of SAE # 2 friction test in oil Apparent friction area (cm ² ) 30 Maximum friction speed (m / sec) 18 Friction time per time (sec) 1.0 Cycle time (engagement period) (sec) 15 Lubricating oil type Idemitsu Dexirone Moment of inertia (kg ・ m ・ sec ² ) 0.031 Total absorbed energy Q (kg ・ m / cm ² ) 10 to 20 For comparison, it was manufactured using a conventional phenolic resin alone. As an example of the friction material, the above-mentioned phenolic resin intermediate was used, and a friction material was manufactured under the same conditions and subjected to the same test. The energy absorption capacity of a material was evaluated by the product Q of the total absorbed energy (Q value) per unit friction area and the instantaneous maximum energy value (value) in the engagement process, as is generally done.

As a result of the test, the dynamic friction coefficient at a surface pressure of 25 kg / cm ² and a friction speed of 5 to 10 m / sec was 0.115 for the comparative material, whereas the present invention material was 0.150, showing a high dynamic friction coefficient. In addition, this test condition was applied with a considerably excessive load in terms of moment of inertia, surface pressure, etc. as compared with the normal use condition up to now, but after friction of 5000 times, the comparison material was 150
The micron wears out and a fine crack is generated on the surface.
In contrast to the limit of the material, in the material of the present invention, the wear was about 30 μm, and the surface condition was hardly changed. Regarding the Q value, the comparative material had a value of 745, whereas the inventive material had a limit of 980 or more.

(See Table 2) Example 2 27.9 parts of epoxidized polybutadiene, 27.9 parts of acetone, and 30 parts of methanol were added to 100 parts of the above-mentioned phenolic resin intermediate to obtain a resin liquid having a nonvolatile content of 50%. The method of manufacturing the friction material and the test conditions were exactly the same as in Example-1.

This friction material had a dynamic friction coefficient of 0.147 at a surface pressure of 25 kg / cm ² and a friction speed of 5 to 10 m / sec, and the limit Q was 955 or more.

Example 3 65 parts of epoxidized polybutadiene, 65 parts of acetone, and 30 parts of methanol were added to 100 parts of the above-mentioned phenol resin intermediate to obtain a resin liquid having a nonvolatile content of 50%. The method of manufacturing the friction material and the test conditions were exactly the same as in Example 1.

The friction material had a dynamic friction coefficient of 0.153 at a surface pressure of 25 kg / cm ² and a friction speed of 5 to 10 m / sec, and had a limit Q value of 1050 or more.

As described above, as a modification method with epoxidized polybutadiene, a preliminary reaction may be performed as in Example 1.
Also, the effect can be recognized by using either of the simple mixing as in Examples 2 and 3. The abrasion resistance seems to be improved by carrying out the preliminary reaction.

The results of the friction test obtained in each of the above Examples are summarized in Table-2.

Example 4 Except that an oxirane oxygen concentration of 14.2 wt% was used in place of the epoxidized polybutadiene of Example 2,
The same procedure as in Example 2 was performed.

This friction material has a dynamic friction coefficient of 0.151 and a limit Q value of 9
It was over 80.

Comparative Example 2 Except that an oxirane oxygen concentration of 7.8% by weight was used instead of the epoxidized polybutadiene of Example 2.
The same procedure as in Example 2 was performed.

The coefficient of kinetic friction of this friction material was 0.135, and fine cracks were generated on the surface after 5000 times of friction, which was almost the limit. The limit Q value at this time was 790.

〔The invention's effect〕

As is clear from the above Examples and Comparative Examples, the wet friction material of the present invention containing a phenol resin modified with epoxy-substitute polybutadiene as an essential component of the binder is remarkably superior to conventional wet friction materials. It was confirmed that it has an excellent dynamic friction coefficient and energy absorption ability.

Claims (1)

[Claims] 1. A wet friction material comprising a phenolic resin modified with epoxidized polybutadiene having an oxirane oxygen concentration of 10 to 15% by weight as a binder.