JPH09264358A - Manufacture of grain and frictional material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dispersibility of starting raw materials, so as to provide a high-quality frictional material in which various kinds of constituent materials are uniformly dispersed, by making organic fibers to be taken as raw materials aggregate while hoe-ding the frictional raw materials other than the organic fibers, and radially projecting a plurality of organic fibers from the front surface. SOLUTION: All organic fibers to be used as raw materials of a frictional material can be used for one component of a grain, on the other hand, the other component is a material other than the organic fiber. As a frictional material raw material other than the organic fiber, friction particles composed of cashew resins or rubber, copper, and sulfur can be mentioned. Next, the organic fibers and the other frictional material raw materials are mixed while being kneeled and crushed, and a green alga-like particle in which a plurality of organic fibers are radially projected from the front surface, or a fluffy pill- like grain can be obtained. Grains are entangled with organic fibers on the front surfaces in pre-performing or aging, and firmly bonded to each other. Therefore, the strength of the frictional material can be increased.

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 for brakes and clutches of various vehicles and industrial machines.

[0002]

BACKGROUND OF THE INVENTION Friction materials widely used for brake pads, brake linings, clutch facings, etc. of various vehicles and industrial machines include fiber materials such as heat-resistant organic fibers, inorganic fibers, and metal fibers, and inorganic / organic fillers. Material, friction modifier and powdered raw material such as thermosetting resin binder are mixed to form a starting material at room temperature at a predetermined pressure (preforming)
And then thermoformed at a predetermined temperature, cured (aftercure) and finished.

[0003] In the above manufacturing process, it is desirable that the various raw materials be present in the friction material in a uniformly distributed manner, and therefore the various raw materials must be mixed more uniformly when the starting raw material is prepared. The method for preparing the starting materials is roughly classified into a wet method in which various raw materials are mixed with a solvent and a dry method in which various raw materials are stirred and mixed as they are. However, in any of the wet method and the dry method, the fiber raw material and the powder raw material have greatly different shapes.
Sufficient stirring is required to uniformly mix the two.
Further, the fiber raw material, especially the organic fiber, has a poor defibration property and is unevenly distributed as a lump in the starting raw material, which lowers the dispersibility of the starting raw material. Furthermore, regarding the adhesion between the fiber raw material and the powder raw material,
The adhesiveness varies depending on the type of powder raw material, which is also a factor that reduces the dispersibility of the starting raw material. Such poor dispersibility of the starting material reduces the homogeneity of the friction material, which is the final product, and the mechanical strength associated therewith. In particular, the difference in the defibration property and the adhesion property is remarkable in the aromatic polyamide fiber (aramid fiber) which is the mainstream of the fiber raw material due to its high heat resistance.

[0004]

As described above, both the wet method and the dry method have a problem regarding the dispersibility of the starting material, and a method for producing a high-quality friction material in which various constituent materials are uniformly dispersed. Is desired. The present invention has been made in view of the above circumstances, and an object thereof is to improve the dispersibility of a starting material and to provide a high-quality friction material in which various constituent materials are uniformly dispersed.

[0005]

Means for Solving the Problems The above-mentioned object is (1) the organic fiber, which is a raw material of a friction material, of the present invention holds a friction material raw material other than the organic fiber and is aggregated, and the surface thereof is A plurality of the organic fibers radially protruding from the granulated product, and (2) the organic fiber is an aromatic polyamide fiber, according to the granulated product according to (1) To be achieved. Also, the same purpose is
The present invention can also be achieved by a method for producing a friction material, which is characterized in that (3) the starting material containing the granulated product according to (1) or (2) above is heat-molded.

In the granulated product according to the present invention, another friction material raw material is attached to the surface of the organic fiber, or the other friction material raw material is incorporated between the fibers in which the organic fiber is entangled to aggregate. The uneven distribution due to the difference in the adhesion of each friction material raw material to the organic fiber is eliminated. Further, when the granulated material is used as the starting material of the friction material, since it exists independently in the starting material, the uneven distribution of the organic fibers due to the poor defibration property is eliminated. Further, the granulated product has the appearance of so-called ball-shaped particles in which a plurality of the organic fibers are radially projected from the surface, or fluffy particles whose surface is fluffed, or a large number of organic fibers extend in a whisker-like shape. ing. Therefore, when a friction material is produced using this granulated material as a starting material, the strength of the resulting friction material is increased because the organic fibers on the surface of the granulated material are entangled and strongly bonded during preforming or thermoforming. Increase. For the same reason, the shape-retaining property and the shape stability are high, for example, handling between pre-molded products such as moving to a heat-molding die becomes easy, or pre-molding becomes unnecessary, and pill-shaped spherical particles (Marimo Granules)
The workability is improved by directly charging (directly) into the thermoforming mold. As described above, the friction material obtained by using the granulated product of the present invention as a starting material has excellent mechanical strength in which various materials are uniformly dispersed. Furthermore, since granules can be created for each type of friction material raw material other than organic fiber,
It is also possible to give the friction material a composition gradient by changing the composition of the granulated product in the thickness direction of the molded product during molding.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The granules according to the present invention and the method for manufacturing a friction material using the granules will be described in detail below. As the organic fiber which is one component of the granulated product of the present invention, all the organic fibers conventionally used as a raw material of a friction material can be used. Among them, heat resistance when used as a friction material by using aromatic polyamide fibers (aramid fibers; commercially available products made by DuPont, trade name "Kevlar", etc.), flame-resistant acrylic fibers and other heat-resistant organic fibers. It is possible to improve the sex. Conventionally, these fibers tend to be unevenly distributed in the starting material and the friction material due to their poor defibration property, but according to the present invention, the uneven distribution can be eliminated.

As the organic fibers, various shapes other than long fibers and short fibers can be used. For example, as shown in FIG. 1 (a), a plurality of short branch fibers are branched from one long trunk fiber, and as shown in FIG. 1 (b), a plurality of long branch fibers are branched from a short trunk fiber. Can be used. These specially shaped organic fibers are
When the granulated product is formed, the relatively long fibers are projected like whiskers on the surface of the granulated product, so that the granulated products can be more firmly bonded to each other.

The other component of the granulated product of the present invention is a material other than the above-mentioned organic fibers among the materials conventionally used as a raw material for friction materials. As the friction material raw material other than the organic fiber, specifically, friction particles such as cashew resin and rubber, metal such as copper, sulfur, aluminum and zinc, or friction such as metal oxide such as alumina, silica and zirconia is used. Modifiers, solid lubricants such as graphite and molybdenum disulfide, scale-like inorganic substances such as vermiculite and mica, fillers such as barium sulfate and calcium carbonate, and phenolic resins (including straight phenolic resins and various modified phenolic resins such as rubber) Examples of the binder include thermosetting resins such as melamine resin, epoxy resin, and cyanate ester resin. These binders may be solid (powder) or liquid.

Then, the above-mentioned organic fiber and other raw materials for the friction material are put into a granulator having a pulling structure and mixed while being ground, whereby the granulated product of the present invention is obtained.
Here, the organic fiber that is a raw material of the friction material is usually obtained as a fiber lump compressed in a state where long fibers and short fibers are intricately entangled with each other. When such a fiber lump is used, the fiber lump is put into a granulating apparatus and crushed for a predetermined time to defibrate to some extent, and then a friction material other than organic fibers is charged to continue crushing. Further, when the organic fibers are defibrated in advance, the organic fibers and other raw materials for the friction material can be simultaneously charged into the granulating device.

Regarding the granulation, for example, the processing conditions such as the grinding time, the pressure of the granulating device, and the rotation speed of the pulling mill, the kind and the input amount of the organic fiber and other friction material raw materials, the lump condition of the organic fiber ( (Compressed state), the desired particle size of the granulated product, etc. are taken into consideration. Further, when a granulated product of the organic fiber and the binder is prepared, the granulation can be promoted by heating and slightly reacting (curing) depending on the kind of the binder.

As shown in FIG. 2, the granulated product of the present invention obtained as described above is a so-called ball-shaped particle (FIG. 2 (a)) in which a plurality of the organic fibers are radially projected from the surface, or The surface has the appearance of fluffy particles having a fluffy surface (FIG. (B)) or fluffy particles having a large number of organic fibers extending like whiskers (FIG. (C)). The difference between these appearances is
It depends on the type of the organic fiber and other raw materials for the friction material and the processing conditions for granulation.

The present invention is further characterized in that a friction material is produced by using the above-mentioned granulated material as a starting material. The manufacturing process will be described below. First, as described above, the organic fibers, which are the raw material of the friction material, and the other raw materials of the friction material are granulated to prepare various granulated materials. The particle size of the granulated product is about 100 μm to 5 mm in consideration of being used as a raw material of the friction material.
Then, these granules are mixed with each other, or if necessary, inorganic fibers or metal fibers are mixed to prepare a starting material. As the inorganic fibers, for example, ceramic fibers such as potassium titanate fibers and alumina fibers, glass fibers, carbon fibers, rock wool and the like can be used alone or in combination. Further, as the metal fiber, copper fiber or steel fiber can be typically used.

The composition of the starting material may be the same as the composition of the normal friction material. In the present invention, since the granulated product is composed of the organic fiber and the other friction material raw material, the granulated material is weighed according to the type of the friction material raw material other than the organic fiber, and mixed to obtain a desired raw material composition. Can be For example, 5 to 15 parts by weight of granules of organic fiber and binder, 1 to 15 parts by weight of granules of friction particles, 5 to 15 parts by weight of granules of solid lubricant, barium sulfate or Granulate with a filler such as calcium carbonate to 30 ~
65 parts by weight, 1 to 15 parts by weight of inorganic fibers and metal fibers are weighed and mixed by stirring to obtain a starting material.

Next, after preforming the above-mentioned starting material into a tablet shape, it is put into a pressure plate and thermoformed into a molded article having a predetermined thickness and density, after-cured and finished to be rubbed. The material is completed. These series of steps can be performed according to a conventional method, for example, preforming is performed at a surface pressure of 100 to 500 Kgf / cm ² ,
Thermoforming is performed at a temperature of 130 to 180 ° C and a surface pressure of 200 to 1000.
Kgf / cm ² is performed for about ³ to 15 minutes, and after-curing is performed at a temperature of 150 to 300 ° C. for about 1 to 15 hours. If desired, scorch treatment may be performed after after-cure. In this scorch treatment, for example, the surface of the friction material is flame-treated for 30 to 300 sec using a burner, or a hot plate heated to 400 to 700 ° C. is heated for 30 to 300 se.
The surface is baked by contacting with c.

Since the granules of the present invention can be handled individually for each friction material raw material other than organic fibers, various granules having different compositions are arranged in the thickness direction of the compact during preforming. The obtained friction material can have a composition gradient.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these. The fiber mass of aramid fiber is put into a high-speed stirring type mixer and stirred for 5 minutes, then phenol resin, barium sulfate and calcium carbonate are charged and the stirring is continued for 10 minutes to granulate the aramid fiber and other raw materials. Got This granulated product was a ball-shaped spherical particle in which a large number of aramid fibers were protruded from the surface in a whisker-like shape.
Similarly, a granulated product of aramid fiber and phenol resin / friction particles / graphite was prepared.

And aramid fiber / phenolic resin /
70% by weight of barium sulfate / calcium carbonate granules and 30% by weight of aramid fiber / phenol resin / friction particle / graphite granules were sufficiently mixed to prepare a starting material. The surface pressure of this starting material is 200 kgf
Preformed into tablets at / cm ² . This preformed product was transferred to a hot press in which a pressure plate was set, and thermoformed at a temperature of 155 ° C. and a surface pressure of 500 Kgf / cm ² for 10 minutes. The thermoformed article is then placed at 200 ° C for 10
Friction material A was prepared by performing time post-cure treatment.

For comparison, phenol resin 10
A starting material obtained by sufficiently stirring and mixing wt%, friction particles 10 wt%, barium sulfate 20 wt%, calcium carbonate 50 wt%, graphite 5 wt% and aramid fiber 5 wt% is preformed in the same manner as above. ,
Friction material B was prepared by thermoforming and after-curing.

Then, the friction materials A and B were subjected to a shear test, a bending test and a component analysis. As a result, the strength was improved in both the shear test and the bending test. Further, in the component analysis, it was observed that the components were not significantly changed in any of the samples randomly sampled from the friction material, and that each component was well dispersed.

[0021]

As described above, in the granulated product according to the present invention, other friction material raw materials adhere to the surface of the organic fiber,
Alternatively, the organic fibers are agglomerated by taking in other friction material raw materials between the entangled fibers, and uneven distribution due to the difference in the adhesion of each friction material raw material to the organic fibers is eliminated. Also,
When the granulated product is used as the starting material of the friction material, since it exists independently in the starting material, uneven distribution of organic fibers due to poor defibration property is eliminated. Further, the granulated product has the appearance of so-called ball-shaped particles in which a plurality of the organic fibers are radially projected from the surface, or fluffy particles whose surface is fluffed, or a large number of organic fibers extend in a whisker-like shape. ing. Therefore, when a friction material is produced using this granulated material as a starting material, the strength of the resulting friction material is increased because the organic fibers on the surface of the granulated material are entangled and strongly bonded during preforming or thermoforming. Increase. For the same reason, the shape retaining property and the shape stability are high, and the handling between the steps such as the movement of the preform to the heat-molding die becomes easy and the workability is improved. As described above, the friction material obtained by using the granulated product of the present invention as a starting material has excellent mechanical strength in which various materials are uniformly dispersed. Furthermore,
Since granules can be created for each type of friction material raw material other than organic fiber, the composition of the granules can be changed in the thickness direction of the compact during molding to give the friction material a composition gradient. You can also

[Brief description of drawings]

FIG. 1 is a diagram showing an example of the shape of an organic fiber used in the present invention.

FIG. 2 is a diagram showing the appearance of the granulated product of the present invention.

Claims (3)

[Claims] 1. An organic fiber as a raw material for a friction material is formed by agglomerating while holding a friction material raw material other than the organic fiber,
A granulated product having a plurality of the organic fibers radially protruding from the surface thereof. 2. The granulated product according to claim 1, wherein the organic fiber is an aromatic polyamide fiber. 3. A method for producing a friction material, which comprises heat-molding a starting material containing the granulated product according to claim 1.