JPH07157748A - Phenolic resin composition for frictional material - Google Patents

Abstract

PURPOSE:To provide the composition consisting essentially of the reaction product of a specific bifunctional phenolic compound and a phenolic compound with an aldehyde compound, excellent in frictional characteristics, heat resistance, flexibility and braking vibration absorbability, large in curability, good in moldability, and reduced in creaking. CONSTITUTION:This composition consists essentially of the reaction product of (A) a bifunctional phenolic compound having an alkyl group at the meta position and a cyclohexyl group at the ortho or para position (e.g. 3-methyl-6- cyclohexylphenol) and (B) a phenolic compound with (C) an aldehyde compound (e.g. formaldehyde). The component A is added in a molar ratio of 0.005-1 to the component B. The reaction product is obtained by charging the components A-C and an acid catalyst such as acetic acid or an alkali catalyst such as NaOH in a reactor, subjecting the mixture to a thermal addition condensation reaction, and subsequently subjecting the reaction product to a dehydration reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenol resin composition for a friction material, which has excellent flexibility and heat resistance and excellent friction characteristics.

[0002]

2. Description of the Related Art Friction materials such as brake linings, disc pads and clutch facings are used in automobiles and industrial machines for braking or transmitting power. These friction materials generally include base materials such as glass fibers, aramid fibers, and metal fibers, organic additives such as cashew dust, melamine dust, and rubber dust, and inorganic additives such as barium sulfate, calcium carbonate, wollastonite, and copper powder. Is bonded with a phenolic resin. On the other hand, with the recent rapid increase in speed of transportation, it is strongly required for these friction materials to improve braking stability under severe conditions and feel by reducing noise. The factor that most affects these properties is said to be the choice of binder.

In order to improve the above-mentioned various properties, research on modified phenolic resins has been actively conducted, and oil-modified phenolic resins, cashew modified phenolic resins, rubber modified phenolic resins, epoxy modified phenolic resins, which are excellent in flexibility,
Melamine-modified phenolic resins have been studied and some have been put to practical use. However, since these modified phenolic resins have poor heat resistance, braking stability under particularly severe conditions cannot be obtained, and squeal occurs, which is insufficient. Further, these phenol resins have a drawback that they are hard to cure and have poor moldability and workability.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to solve the above-mentioned problems of conventional friction materials.
An object of the present invention is to provide a phenol resin composition for a friction material, which has excellent heat resistance and flexibility, quick curing, and good moldability.

[0005]

Means for Solving the Problems In the present invention, as a result of intensive studies for solving the above-mentioned problems, it was found that specific bifunctional phenols having a small number of cross-linking points greatly affect these characteristics. The invention has been completed. That is, in the present invention, the friction material composition contains as an essential component a reaction product of a bifunctional phenol having an alkyl group at the meta position and a cyclohexyl group at the ortho position or the para position, and a phenol and an aldehyde. And a phenolic resin composition for a friction material.

The present invention will be specifically described below.
When bifunctional phenols, phenols, and aldehydes are reacted and cured under an acid or alkali catalyst, or when a curing agent is added and cured, the number of cross-linking points is reduced, resulting in a flexible cured product. To be In addition, 2 having a cyclohexyl group in the ortho or para position used in the present invention
Functionalized phenols have higher heat resistance than conventional bifunctional phenols having an aliphatic long-chain alkyl group, and the phenol resin modified with this is superior in heat resistance to the conventional modified phenolic resin. Furthermore, since the bifunctional phenols used in the present invention react uniformly with the phenols, it is possible to obtain a phenol resin for a friction material, which cures quickly and has excellent moldability.

In the modified phenolic resin of the present invention, the molar ratio of the bifunctional phenol having an alkyl group at the meta position and a cyclohexyl group at the ortho position or the para position to the phenols is preferably 0.005 to 1.0. The molar ratio is 0.
If it is 005 or less, the flexibility and heat resistance which are the characteristics of the modified resin of the present invention cannot be obtained. Moreover, this ratio is 1.
When it exceeds 0, the curing of the obtained resin is delayed, and the molding time of the friction material becomes extremely long.

As the bifunctional phenol, one having a methyl group, an ethyl group, a propyl group, a butyl group or the like at the meta position and a cyclohexyl group at the ortho position or the para position can be used alone or in combination. it can. As the phenols, phenol, cresol, xylenol, resorcin, catechol, hydroquinone, bisphenol A, bisphenol F and the like can be used alone or in combination. As aldehydes, formaldehyde, paraformaldehyde, trioxane,
Acetaldehyde, benzaldehyde and the like can be used alone or in combination.

In the present invention, the acidic substances used as the catalyst include organic acids such as acetic acid, formic acid, oxalic acid, maleic acid and paratoluenesulfonic acid, and inorganic acids such as nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid. These can be used alone or in combination. The alkaline substance used as a catalyst is sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide, barium hydroxide, aqueous ammonia, etc., which are used alone or in combination. I can do things. The phenol resin of the present invention can be obtained by charging these phenols, formaldehydes and catalysts into a reaction vessel, heating them for addition condensation, and then subjecting them to a dehydration reaction.

[0010]

EXAMPLES The present invention will be described below with reference to examples. However, the present invention is not limited to these examples. In addition, "part" described in Examples and Comparative Examples
And "%" all indicate "parts by weight" and "% by weight". Example 1 A reaction vessel equipped with a condenser and a stirrer contained 1000 parts of phenol, 693 parts of 37% formalin, and 10 parts of oxalic acid.
Parts, and additionally 300 parts of 3-methyl-6-cyclohexylphenol. The temperature was gradually raised, and after reaching 95 ° C., a reflux reaction was performed for 180 minutes. Then, dehydration reaction is carried out, and when the temperature reaches 150 ° C., the dehydration reaction is carried out under reduced pressure of 60 Torr, and after reaching the temperature of 230 ° C., 1400 parts of novolac type phenol resin which is solid at room temperature is taken out from the reaction vessel. Got

Example 2 1400 parts of a solid novolac type phenol resin at room temperature was obtained in the same manner as in Example 1 except that 3-ethyl-6-cyclohexylphenol was used instead of 3-methyl-6-cyclohexylphenol. . Example 3 A reaction vessel equipped with a condenser and a stirrer was charged with 1000 parts of phenol, 787 parts of 37% formalin, 10 parts of caustic soda, and 300 parts of 3-methyl-6-cyclohexylphenol. After gradually raising the temperature to 95 ° C., a reflux reaction was carried out for 40 minutes. Then 60 To
The dehydration reaction was performed under reduced pressure of rr, the temperature reached 80 ° C., the aging reaction was performed at that temperature for 120 minutes, and then discharged from the reaction container to obtain 1500 parts of a solid resol-type phenol resin at room temperature. .

Comparative Example 1 Phenol 1000 was charged.
Parts, 37% formalin 600 parts, and oxalic acid 10 parts were obtained in the same manner as in Example 1 to obtain 1100 parts of a solid novolac type phenol resin at room temperature. Comparative Example 2 Novolak solid at room temperature in the same manner as in Example 1 except that 1000 parts of phenol, 1350 parts of 37% formalin, 10 parts of oxalic acid, and 2500 parts of 3-methyl-6-cyclohexylphenol were used. Type phenol resin 3
600 parts were obtained.

Comparative Example 3 Phenol 1000 was charged.
Parts, 680 parts of 37% formalin and 10 parts of caustic soda were obtained in the same manner as in Example 3 to obtain 1200 parts of a solid resol-type phenol resin at room temperature.

The four kinds of phenolic resins obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were pulverized separately with hexamine to give powders, and in Example 3 and Comparative Example 3, powders were pulverized as they were. And mixed in the following mixing ratio. Compounding amount (wt%) Aramid fiber 5 Barium sulfate 65 Resin 10 Copper powder 10 Graphite 10

The composition was heated at a temperature of 160 ° C. and a pressure of 200 kg.
/ Cm ² for 10 minutes and then baked at 200 ° C. for 5 hours to prepare a test piece. These were subjected to a friction test according to JIS D 4411, and the results are shown in FIGS. 1 and 2. The results of Rockwell hardness measurement are shown in FIG. As is clear from FIG. 1, in Examples 1, 2, and 3, compared with Comparative Examples 1, 2, and 3, the decrease in friction coefficient at high temperature is small. From FIG. 2, it is clear that the amount of wear is small and the heat resistance is excellent. Moreover, in FIG. 3, the hardness of Examples 1, 2, and 3 is low,
It is clear that it has excellent flexibility.

[0016]

The friction material using the phenol resin composition according to the present invention as a binder is flexible and has excellent vibration absorption by braking. Further, even when braking under severe conditions, the friction coefficient is stable, the wear resistance and mechanical strength are excellent, and the squeal is reduced, which is suitable for braking parts for automobiles, railway vehicles, aircrafts, and industrial machines.

[Brief description of drawings]

FIG. 1 is a graph showing friction test results (temperature and friction coefficient) of Examples and Comparative Examples.

FIG. 2 is a graph showing friction test results (temperature and wear amount) of Examples and Comparative Examples.

FIG. 3 is a graph showing Rockwell hardness of Examples and Comparative Examples.

Claims (4)

[Claims] 1. A friction material comprising as an essential component a bifunctional phenol having an alkyl group at the meta position and a cyclohexyl group at the ortho position or the para position, and a reaction product of a phenol and an aldehyde. Phenolic resin composition. 2. The phenol for friction material according to claim 1, wherein the bifunctional phenols according to claim 1 are contained in a molar ratio of 0.005 to 1.0 with respect to the phenols. Resin composition. 3. The friction material according to claim 1, wherein the reaction product of the bifunctional phenols, the phenols and the aldehydes according to claim 1 has been reacted with an acid as a catalyst. Phenolic resin composition. 4. The friction material according to claim 1, wherein the reaction product of the bifunctional phenols, the phenols and the aldehydes according to claim 1 has been reacted with an alkali as a catalyst. Phenolic resin composition.