JPH0570610A - Method for producing friction material - Google Patents

Abstract

PURPOSE:To obtain a friction material for parts of automobile, etc., having a stable coefficient of friction, excellent wear ratio and friction sound by molding a composition for friction material comprising a phenol resin, metal fibers except iron fibers and wood flour and burning the molded article in a nonoxidizing atmosphere under a specific condition. CONSTITUTION:A composition for friction material composed of 10-30vol.% phenol resin such as novolak type phenol resin, metal fibers except iron fibers and 5-15vol.% wood flour is prepared, uniformly blended with wollastonite, barium sulfate, molybdenum disulfide, graphite, etc., and mixed with about 5wt.% based on total weight, of trichlene. Then the mixture is dried at 80'C for about one hour to give molding powder, which is further molded at 145 deg.C under 600kgf/cm<2> for eight minutes to give a friction material. The friction material is burnt in a nonoxidizing atmosphere such as nitrogen at 300-500 deg.C for 1-2 hours and the wood flour in the friction material is carbonized to give the objective friction material having an improved coefficient of friction and improved wear resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for friction materials, and in particular, it is based on inorganic fibers, organic fibers and metal fibers used as braking parts for automobiles, railway vehicles, industrial machines and the like. The present invention relates to a method for manufacturing a friction material.

[0002]

2. Description of the Related Art Conventionally, friction materials have been used for braking automobiles and various industrial machines. This friction material is generally based on inorganic fibers such as asbestos and ceramic fibers, organic fibers such as polyimide, polyamide and phenolic resins, and metal fibers such as brass and copper, which are used as friction and friction reducing agents. It is made from a composite material with the addition of modifiers, additives and binders. The characteristics required of this friction material include the coefficient of friction, the amount of wear, the aggressiveness to the mating metal plate, the friction performance such as squeal, the bending strength, and the shear strength.

With the recent increase in speed of transportation and the increase in size of wheels, friction materials have come to be used under more severe conditions such as high speed and high load. It is necessary for the friction material to have excellent squealing and wear resistance under a wider range of conditions, and conventional friction materials cannot satisfy these characteristics. As a method of improving the squeal, there is a method of increasing the porosity of the friction material, based on the findings so far. However, generally, when the porosity is increased, there is a problem that the strength of the friction material is reduced and wear is deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a resin composition for a friction material which does not have the above-mentioned problems, and an object thereof is to provide a method for producing a friction material having an improved friction coefficient and wear resistance. It was done.

[0005]

As a result of various studies to solve the above problems, the present inventors have found a method for producing a friction material having a large porosity and a high strength. The invention was completed. That is, the present invention is 10 to 30 vol% phenol resin, 5 to 30 metal fibers
forming a friction material composition containing 5% to 15% by volume of wood powder and 5 to 15% by volume of wood powder, and further 300 to 500 ° C. in a non-oxidizing atmosphere.
It is characterized in that the wood flour is carbonized by firing at a temperature of 1 to 2 hours.

One of the methods for improving the squeal of the friction material is to increase the porosity. To increase the porosity,
There are methods such as reducing the amount of resin as a binder, using long fibers as a base material, and reducing the amount of material filled during molding. However, these methods have problems that the strength of the friction material is remarkably reduced, and a uniform friction material cannot be stably manufactured. Therefore, as a result of various studies, by uniformly mixing wood powder having a high carbonization rate, molding this, and further firing in a non-oxidizing atmosphere at 300 to 400 ° C. for 1 to 2 hours to carbonize the wood powder, It was found that the porosity can be increased stably.

The wood powder used in the present invention is not particularly limited, but a particle size of 100 mesh pass is preferable. If the particle size is larger than the 100-mesh pass, the voids become large and the strength decreases. Further, a resin cured product other than wood powder is also carbonized, but the carbonization temperature is almost the same as the carbonization temperature of the binder. If the carbonization temperature is too high, the carbonization of the resin will proceed excessively and the strength will be reduced under the condition that the additive is sufficiently carbonized. On the other hand, if the carbonization is carried out at a low temperature, the carbonization becomes insufficient, the amount of gas generated at the time of use increases, and the fading reduction easily occurs. Therefore, it is essential that the additive has a lower carbonization temperature than the resin. Wood flour is the best choice for this.

As the phenol resin used in the present invention, a novolac type phenol resin using a curing agent such as hexamethylenetetramine, a self-curing resol type phenol resin and a modified phenol resin are used. As the modified phenol resin, various modified resins such as cash oil, rubber-modified cash-modified phenol resin, oil-modified phenol resin, rubber-modified phenol resin, and melamine-modified phenol resin are used. In the present invention, these conventionally used phenol resins and modified phenol resins can be used alone or in combination, but preferably 4
It is desirable to use a resin in which decomposition products and volatile substances are reduced at a temperature of 00 to 500 ° C.

As the base material used in the present invention, non-ferrous metal fibers such as copper and brass are used alone or in combination of 5 to 30% by volume. Also, ceramic fiber, glass fiber,
Inorganic fibers such as wollastonite and artificial mineral fibers, organic fibers such as polyimide fibers, polyamide fibers and phenol fibers, and lubricants such as silica, antifriction agents such as graphite and molybdenum disulfide, etc. And organic additives such as rubber can be used alone or in combination. However, it is desirable that the base material, the filler and the like used in the present invention have excellent heat resistance such as organic substances or metallic substances. If a base material having low heat resistance or a filler is used, the strength may decrease.

The above additives are uniformly mixed with a mixer such as a Henschel mixer and a kneader which have been used so far.
The friction material composition is obtained by drying. Next, this friction material composition is hot-press molded at 130 to 160 ° C. to obtain a friction material molded product. Furthermore, if necessary, this friction material molded product can be
Heat treatment is performed for a predetermined time. The steps up to this point are the same as those of the conventional friction material molded product, and are not limited to the above conditions.

This friction material molded product was subjected to 30 times in a non-oxidizing atmosphere.
The wood flour is carbonized by firing at a temperature of 0 to 500 ° C. for 1 to 2 hours. The atmosphere needs to be a non-oxidizing atmosphere such as in nitrogen gas, and in an oxidizing atmosphere such as in air, the resin as a binder is deteriorated, resulting in a decrease in strength and wear. Also,
The treatment temperature is preferably 300 to 500 ° C., and 300 to 45
0 ° C is optimal. When the temperature is 300 ° C or lower, carbonization of the wood powder becomes insufficient, so that gas is often generated during use and fading easily occurs. On the other hand, when the temperature is 500 ° C. or higher, the thermal decomposition of the resin that is the binder proceeds, and the strength decreases significantly.

[0012]

【Example】

Example 1 Examples of the present invention will be described below, but the present invention is not limited thereto. Novolak type phenolic resin 24vol%, maximum particle size 100 mesh or less wood powder 8v
ol%, copper fiber 25vol%, wollastonite 5vo
1%, barium sulfate 18vol%, molybdenum disulfide 5
The composition of vol% and graphite 15 vol% is uniformly mixed,
Then, 5% of trichlene is added to the total weight and further mixed. This mixture was dried at 80 ° C. for about 1 hour to obtain a molding powder. This powder is 145 ° C, 600 kgf / cm
^The friction material was obtained by molding for 8 minutes under the condition of ² . Further, the wood powder in the friction material was carbonized by heat treatment at 400 ° C. for 1 hour in a nitrogen atmosphere.

Example 2 Novolak type phenolic resin 23 vol%, maximum particle size 1
Wood powder 10vol% less than 00 mesh, brass fiber 25v
ol%, wollastonite 5vol%, Kevlar fiber 1
A composition of 0 vol%, 15 vol% of barium sulfate, 5 vol% of molybdenum disulfide and 15 vol% of graphite is uniformly mixed, and 5% of trichlene is added to the total weight and further mixed. This mixture was dried at 80 ° C. for 1 hour to obtain a molding powder. This powder is 145 ° C., 600 kgf / cm ²
A friction material was obtained by molding for 8 minutes under the above condition. This friction material was heat treated in the same manner as in Example 1 to obtain a friction material.

Comparative Example 1 Novolak type phenolic resin 24 vol%, copper fiber 25
vol%, wollastonite 5 vol%, barium sulfate 18 vol%, molybdenum disulfide 5 vol%, graphite 15
A vol% composition was uniformly mixed, and a friction material was obtained in the same manner as in the example. Comparative Example 2 Novolac type phenolic resin 24 vol%, copper fiber 25
vol%, wollastonite 5 vol%, barium sulfate 18 vol%, molybdenum disulfide 5 vol%, graphite 15
A vol% composition was uniformly mixed, and a friction material was obtained in the same manner as in the example. 400 this friction material in a nitrogen atmosphere
A friction material was obtained by treating at 1 ° C for 1 hour. Table 1 shows the friction characteristics of the friction materials obtained in Examples and Comparative Examples. It can be seen that the friction material obtained by the method of the example has a stable friction coefficient and is excellent in wear rate and squeal.

[0015]

INDUSTRIAL APPLICABILITY The present invention relates to a phenol resin of 10 to 30v.
a composition for a friction material containing 5% to 15% by volume of metal fibers excluding iron fiber and 5 to 15% by weight of wood powder, and further fired at a temperature of 300 to 500 ° C. for 1 to 2 hours in a non-oxidizing atmosphere. Since it is configured, it is possible to provide a method of manufacturing a friction material having a stable friction coefficient and excellent wear rate and squeal.

[Table 1] Friction characteristics

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Hio Baba 1500 Ogawa, Shimodate, Ibaraki Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Takaaki Kurita 1500 Ogawa, Shimodate, Ibaraki Hitachi Chemical Co., Ltd. Company Shimodate Institute

Claims (1)

[Claims] 1. Phenolic resin 10 to 30% by volume, metal fiber excluding iron fiber 5 to 30% by volume, and wood powder 5 to 15%
A method for producing a friction material, which comprises forming a composition for a friction material containing ol%, and further firing the composition at a temperature of 300 to 500 ° C. for 1 to 2 hours in a non-oxidizing atmosphere.