JPH06854B2 - Method of manufacturing friction material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a friction material used for sliding parts such as brakes and clutches of automobiles, vehicles, and industrial machines, that is, brake linings, clutch facings, and disc brake pads. The present invention relates to a method for manufacturing a friction material used as the above.

[Conventional technology]

Conventionally, a friction material using asbestos as a base material has been generally used for the above-mentioned applications, and this friction material is combined with asbestos as a base material and various additives and bonding agents for improving the characteristics of the friction material. It is manufactured by compression molding a mixture of agents.

The characteristics required of the friction material are that it is suitable for a specific application, has a stable coefficient of friction under various conditions, has less wear on the facing surface that is a friction partner with the friction material itself, and is suitable. And the like.

[Problems to be solved by the invention]

Although conventionally known asbestos-based friction materials satisfy these characteristics, asbestos has recently been pointed out to be harmful to the human body as a result of its use, and its use is being regulated,
The demand for friction materials that do not use asbestos is increasing.

Therefore, many proposals have been made for friction materials that do not use asbestos, but conventional non-asbestos-based friction materials have a problem in terms of judder property, particularly during start-up, and improvement thereof is desired. .

[Means for solving problems]

The inventors of the present invention, in view of the problems of the asbestos-based friction material as described above, as a result of earnest research for the purpose of providing a friction material having excellent judder performance without using asbestos, The present invention has been completed, and the structure of the present invention is
260% after molding with non-asbestos base material, binder and filler as main materials
The main feature is heat treatment at ~ 320 ° C.

Next, the present invention will be described in detail.

The inventors of the present invention have used, as a base material, short fibers such as glass fiber, carbon fiber, phenol fiber, aramid fiber, and ceramic fiber, long fiber, spun yarn, and fiber-spreading instead of asbestos. A thermosetting resin such as phenol or melamine, a synthetic rubber or a natural rubber as a binder, and barium sulfate or magnesium carbonate as a filler, and a desired clutch facing such as clutch facing. When heat-treating after forming into a shape, heating temperature is 260 ~ 3
The present invention has been completed by knowing that a friction material having a good judder performance can be obtained by setting the temperature to 20 ° C.

Further, various additives for improving friction characteristics are usually called friction modifiers, and known raw materials can be used in the present invention as in the conventional case.

For example, cashew dust (powder of cashew grain oil polymer), resin dust, organic powder such as rubber dust, copper,
Powders of metals such as brass, zinc, lead, tin and aluminum, and powders of inorganic substances such as baryta, calcium carbonate and calcium hydroxide can be used.

The main point of the present invention is to use a non-asbestos base material and to raise the temperature during heat treatment.
Friction performance Especially, good judder performance is obtained, and a good friction material comparable to that using asbestos as a base material can be obtained.

The mixture obtained by mixing the above components in a specific ratio is molded by a conventionally known method, and in the heat treatment step after molding, 26
A product of friction material can be obtained by heat treatment at a temperature of 0 to 320 ° C.

When the friction material obtained by such a method is used for a clutch facing and used for a clutch of an automobile, the judder property is remarkably improved.

The heat treatment temperature after molding of the conventional friction material using a non-asbestos base material is 200 to 250 ° C. as disclosed in, for example, JP-A-56-167934, and under this condition, the clutch facing is actually used. As a result of prototyping, the desired judder property was not obtained. It is presumed that this was because heating did not reach the inside of the thermosetting resin such as phenol resin used as the binder, and the resin was insufficiently cured, causing a problem in judder property.

However, since the friction material obtained by the method of the present invention has a heating temperature of 260 to 320 ° C. in the heat treatment step, the thermosetting resin such as the phenol resin used as the binder is uniformly cured, resulting in judder performance. It is a good friction material. In the heat treatment step, if heated to 320 ° C. or higher, thermal decomposition of the binder progresses and the strength becomes weak, and the lubricity becomes insufficient and the judder property deteriorates.

The heating temperature in the heat treatment step of the present invention may be 260 to 320 ° C. from the beginning, but it is 200 ° C. in order to avoid problems such as blistering and cracking due to rapid high temperature heating. After heating for 3 to 5 hours, heating may be performed stepwise such as heating at 270 ° C. for 12 hours. The point is that the final heating may be carried out uniformly at 260 to 320 ° C., so that the binder is evenly heated to prevent the binder from being insufficiently cured.

Further, it has been found that the above effect is further enhanced by combining the heating in the non-oxidizing atmosphere and the subsequent heating in the air atmosphere in the heat treatment.

〔Example〕

 Next, examples of the present invention will be described.

Example 1 Glass filament 1000TEX having a diameter of 6 μm was used 28 times / 250 mm.
The yarn (A) was obtained by applying two S-twisted yarns of 40 times to 250-mm Z-twisted yarns and inserting one brass wire.

Add 2 parts of liquid melamine-modified phenolic resin to this yarn (A).
After impregnating with 0% by weight and drying at 100 ° C. for 5 minutes, 100% by weight of the rubber binder (B) was adhered and dried at 100 ° C. for 5 minutes. The rubber binder (B) is 100 parts by weight of SBR rubber, 26 parts by weight of sulfur, zinc white, vulcanization accelerator, 40 parts by weight of filler such as barium sulfate and magnesium carbonate, carbon black, powdered phenolic resin, A mixture of 32 parts by weight of a reinforcing agent such as Kevlar pulp and 2 parts by weight of a friction modifier was dissolved in rubber and used.

Put the product obtained as described above into a mold, and set the temperature to 180
A molded product (C) was obtained by heat-press molding at a temperature of 100 ° C and a pressure of 100 kg / cm ² . At this time, degassing is performed 4 to 5 times in the initial stage of pressurization,
The total molding time was 7 minutes. 6 this molded product at 260 ℃
After heat treatment for a time, the surface was polished to obtain a clutch facing having a thickness of 3.5 mm.

Example 2 Using the yarn (A) and the binder (B) in Example 1, 100% by weight of the rubber binder (B) was attached to the yarn (A),
It was dried at 100 ° C. for 5 minutes.

Put the product obtained as described above into a mold, and set the temperature to 180
A molded product (D) was obtained by heat and pressure molding at a temperature of 100 ° C. and a pressure of 100 kg / cm ² . At this time, as in Example 1, degassing was performed 4 to 5 times in the initial stage of pressurization, and the total molding time was 7 minutes. This molded product is heat treated at 180 ℃ for 5 hours and then at 320 ℃ for 6 hours.
After heat treatment for a time, the surface was polished to obtain a clutch facing having a thickness of 3.5 mm.

Example 3 The surface of the molded product (C) of Example 1 was polished and heat-treated at 260 ° C. for 6 hours to obtain a clutch facing having a thickness of 3.5 mm.

Example 4 The yarn (A) of Example 1 was impregnated with 20% by weight of liquid melamine-modified phenol, dried at 100 ° C. for 5 minutes, 100% by weight of a rubber binder (B ′) was adhered, and the mixture was heated at 100 ° C. for 5 minutes. Allow to dry for minutes. The rubber binder (B ′) was prepared by dissolving 20 parts by weight of SBR, 42 parts by weight of the filler of Example 1, 37 parts by weight of reinforcing agent, and 1 part by weight of friction modifier in a rubber composition. Using.

Put the product obtained as described above into a mold, and set the temperature to 180
A molded product (C ′) was obtained by heat and pressure molding at a temperature of 100 ° C. and a pressure of 100 kg / cm ² . This molded product was placed in a nitrogen atmosphere at 260 ° C for 6
After heat-treating for 6 hours, it was further heat-treated at 260 ° C. for 6 hours in the atmosphere, and the surface was polished to obtain a clutch facing having a thickness of 3.5 mm.

Example 5 Using the yarn (A) and the binder (B ′) in Example 4,
100% by weight of the rubber binder (B ') is attached to the yarn (A),
It was dried at 100 ° C. for 5 minutes.

Put the product obtained as described above into a mold, and set the temperature to 180
A molded product was obtained by heat-press molding under conditions of ° C and a pressure of 100 kg / cm ² . This molded product was heat-treated at 180 ° C for 5 hours in a nitrogen atmosphere, then at 300 ° C for 6 hours, and then heat-treated at 300 ° C for 6 hours in the air, and the surface was polished to a thickness of 3.5 mm. Got the clutch facing.

Comparative Example 1 The heat treatment conditions of Example 1 were performed at 250 ° C. for 6 hours, and after the heat treatment, the surface was polished to obtain a clutch facing having a thickness of 3.5 mm.

Comparative Example 2 The molded product (C ′) of Example 4 was heated at 260 ° C. in a nitrogen atmosphere.
After heat-treating for 6 hours, the surface was polished to obtain a clutch facing having a thickness of 3.5 mm.

Each of the clutch facings obtained in Examples 1 to 5 and Comparative Examples 1 and 2 was attached to an automobile (Toyota Motor Corporation, Liteace), and the maximum value of the longitudinal vibration of the vehicle body at the time of starting the first speed was measured with an accelerometer. This operation was repeated 160 times, and the judder resistance was expressed by the average value thereof.

As is clear from the above table, the friction material obtained by the method of the present invention has improved judder resistance as compared with the conventional product.
Further, the other performances required for the friction material of the friction material were the same as those of the conventional non-asbestos friction material.

Claims (2)

[Claims] 1. A method for producing a friction material, which comprises a non-asbestos base material, a binder and a filler as main materials, and heat-treats at 260 to 320 ° C. after molding. 2. A non-asbestos base material, a binder, and a filler as main materials, which are heat-treated at 260 to 320 ° C. in a non-oxidizing atmosphere after molding and further heat-treated at 260 to 320 ° C. in an air atmosphere. And a method for manufacturing a friction material.