JPH0693111A - Asbestos-free friction material - Google Patents

Abstract

PURPOSE:To provide a material which does not contain asbestos as a fibrous ingredient and is less apt to create noise. CONSTITUTION:The material, to be used as an automotive brake pad, brake lining, clutch facing, etc., comprises a non-asbestine fibrous ingredient, a thermoset resin, e.g. a phenolic resin, and a filler, e.g. graphite or barium sulfate, and is obtained by incorporating a thermoset resin as at least part of an uncured friction material to be introduced near a backing plate and then conducting pressure molding with heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material used as a disc brake, a drum brake, a clutch facing of an automobile, and the like, and relates to a non-asbestos friction material which does not contain asbestos as a fiber component and produces little squeal. is there.

[0002]

2. Description of the Related Art Conventionally, asbestos has been often used as a base material for friction materials used for automobile disc brakes, drum brakes, clutch facings, etc. However, asbestos is harmful to humans due to its dust. As a result of being pointed out, its use is being regulated, and there is a strong demand for friction materials that do not use asbestos.

Therefore, many proposals have been made for non-asbestos-based friction materials that do not use asbestos, but most of them use inorganic fibers such as heat-resistant organic fibers, glass fibers, and metal fibers as a fiber component, and use them as binders. A thermosetting resin such as phenol resin is used as the filler, and an abrasive such as alumina or zirconium silicate or a lubricant such as graphite or molybdenum disulfide is used as the filler.

[0004]

The main performances required of the friction material using the thermosetting resin such as the phenol resin as described above are a reasonably high and stable friction coefficient, excellent fade resistance, and resistance to fade. Abrasion resistance, face-to-face aggression, and squealing performance are listed.

Among these, several types of squeal patterns and a number of squeal factors can be cited as the squeal that occurs during braking, and in order to reduce the squeal, other performance may have to be sacrificed. , Is a very difficult problem to solve. For example, if a filler with high hardness is used to increase the braking effect or improve wear resistance, squeal easily occurs, and if a large amount of lubricant is used, squeal hardly occurs, but the friction coefficient is There is a problem of decrease.

To date, the main methods proposed to prevent the generation of squeal without affecting other performances are as follows: (1) The composition having good vibration characteristics is used as a part of the friction material. Provided composite friction material, (2) Friction material in which the hardness distribution on the surface of the friction material is devised so that friction vibration does not easily occur, (3) Porosity is made larger in the part near the friction surface than in other parts Friction material, (4) Friction material including a cushioning material containing a lot of rubber particles between the friction material and the back metal.

However, (1) and (2) have drawbacks such as high manufacturing cost, and (3) is when the constituent components of the friction material are changed in order to change the porosity in the inner thickness direction of the friction material. However, there are drawbacks such as cracks due to temperature change and reduction of strength, and there is a drawback that the molding process becomes complicated when the constituents of the friction material are the same, and (4) has a problem of strength at the boundary surface where constituents are different. Therefore, the problem to be solved by the present invention is to provide a non-asbestos-based friction material which does not have the above-mentioned problems and has less squeaking during braking.

[0008]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and its constitution is such that a fiber component other than asbestos, a thermosetting resin component such as phenol resin, and graphite are filled. In the friction material containing the material component,
It is characterized in that a thermosetting resin which has already been cured is contained in a portion near the back metal as a part of the friction component, and then heated and pressed.

That is, the inventor of the present invention was found to have a good friction coefficient,
As a result of repeated research aimed at obtaining a non-asbestos-based friction material that does not reduce the squeal of the brake easily by the conventional method without impairing the fade resistance, wear resistance, and face-to-face attacking property, the result shows that After including a cured thermosetting resin in at least a part of the friction material component, it is known that the above objects can be achieved by heating and pressing,
The present invention has been accomplished.

The hardened thermosetting resin is optimally the same as the thermosetting resin used as the binder, and if different ones are used, the strength may decrease. Further, the total content of the hardened thermosetting resin and the uncured thermosetting resin is constant in any part of the friction material so that the components of the friction material completed by heat and pressure molding are uniform. Is preferably adjusted as follows. The portion using the cured thermosetting resin tends to have a higher porosity than the other portions, but it is desirable not to increase the porosity by 8% or more from the viewpoint of strength.

As a means for carrying out the present invention, for example, a material containing a thermosetting resin powder which has been hardened in advance and a material not containing it are prepared, and integrally molded according to the time of heat and pressure molding, or the simplest method. As a conventional method, it is conceivable to carry out a pre-molding method, in which only the back metal portion is heated to cure a part of the thermosetting resin in the vicinity of the back metal, and then heat press molding is performed.

The fibers used in the present invention include organic fibers such as aramid fibers, inorganic fibers such as glass fibers, rock wool and ceramic fibers,
Examples include metal fibers such as copper, bronze, aluminum, and brass.

The binder may be a thermosetting resin such as phenol resin, urea resin, melamine resin or modified resin thereof, or heat resistant resin such as polyacetal, aromatic polyimide resin or fluororesin. Examples of the material include graphite, metal powder, molybdenum disulfide, cashew dust and the like having a lubricating action, barium sulfate, calcium carbonate and the like.

[0014]

The friction material of the present invention is a non-asbestos friction material, and at least a part of the friction material in the vicinity of the backing metal is mixed with the cured thermosetting resin, and then heat and pressure molding is performed. Even if the material composition is uniform, a part having a different configuration from the other parts occurs in the vicinity of the back metal, which absorbs frictional vibrations and reduces squeaking during braking. Moreover, since the conventional friction material is used in the vicinity of the friction surface, it does not impair the friction performance, wear resistance, face-to-face aggression, etc., and the content of the uncured and cured thermosetting resin can be adjusted. If the components of the friction material become uniform when the product is finished, the strength of the friction material is almost the same as the conventional one.

[0015]

EXAMPLES Next, examples of the present invention will be described. Although several methods can be considered as the method for carrying out the present invention as described above, a method in which a material containing a thermosetting resin powder that has been previously hardened and a material that does not include the hardened resin powder are prepared and integrally molded at the time of heat and pressure molding Will be described in detail.

Phenolic resin is used as a binder, aramid fiber or glass fiber is used as a fiber base, and cashew dust, calcium carbonate, barium sulfate, copper powder, magnesium oxide, graphite are used as filler components, and after curing at 200 ° C.,
The pulverized hardened phenol resin powders were mixed uniformly to prepare friction materials for Examples a to c shown in Table 11 and friction materials for Comparative Example d. In addition, the numerical value in a table shows volume%.

Next, using the same weights of the friction material a and the friction material d, the friction material a is first put in the mold and the upper part is leveled, and the friction material d is put on the friction material a and the temperature is 150 kg / cm ² at room temperature. Was pressed for 30 seconds, and a preform was prepared in which the friction material a was in the vicinity of the die and the friction material d was in the friction surface portion. This preform is then heated to 150 ° C and pressure of 200kg / cm.
After heat and pressure molding at ² for 7 minutes, heat treatment was performed at 200 ° C. for 6 hours to obtain the friction material for the brake lining for trucks of Example A shown in Table 2. Similarly, friction materials for truck brake linings of Examples B and C and Comparative Example D shown in Table 2 were obtained.

The friction materials of the examples and comparative examples produced by the above method were placed in a state where a microphone was placed near the brake, and a brake device dynamometer test for trucks and buses (JASO C407-82, inertia 40 kgs ² , reduction) Table 2 shows the results of the test and analysis based on the speed of 0.2 g). Incidentally, a test piece was cut out from the friction material A, B, C, D in the vicinity of the back metal, and JASO C444-7
When the porosity was measured based on the porosity test method of No. 8, it was 4%, 7%, 10%, and 2%, respectively.

[0019]

INDUSTRIAL APPLICABILITY As described above, the non-asbestos-based friction material of the present invention which does not contain asbestos as a fiber base material has a thermosetting property in which at least a part of the friction material in the vicinity of the back metal is cured as shown in the examples. It is characterized in that it is heated and pressed after resin is added. As described above, the squeal of the brake is reduced, so it is suitable as a friction material used for automobile disk pads, brake linings, clutch facings, etc. is there.

[0020]

[Table 1]

[0021]

[Table 2]

Claims (4)

[Claims] 1. A non-asbestos-based friction material containing a fiber component other than asbestos, a thermosetting resin component such as a phenol resin, and a filler component such as graphite or barium sulfate, and at least the friction material component in the vicinity of the backing metal. A non-asbestos-based friction material, characterized in that it is obtained by heat-press molding after part of a cured thermosetting resin is included. 2. A portion containing a thermosetting resin that has been cured before heating and pressurizing is layered in parallel with the back metal, and the thickness thereof is 2/3 or less of the thickness of the entire friction material. The non-asbestos friction material according to claim 1. 3. The porosity of a portion containing a thermosetting resin which has been cured before heat-press molding is 2 to 8% higher than that of other portions when the finished product is obtained. The non-asbestos friction material according to claim 1. 4. Fiber components other than asbestos include organic fibers such as aramid fibers, glass fibers, rock wool, ceramic fibers, inorganic fibers such as potassium titanate fibers, copper, bronze,
The non-asbestos friction material according to claim 1, which is a metal fiber such as aluminum or brass.