JP2001330065A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction material having excellent fade resistant characteristic and the sound vibration characteristic and capable of preventing the lowering of the abrasion resistance and the shearing strength. SOLUTION: This friction material contains one kind or more of the fiber material and one kind or more of the inorganic material and/or the organic material having the maximum granular diameter at 500 μm or more. Furthermore, a part of these materials is formed into a spherical lump and/or a nearly spherical lump with 2 mm or more of diameter, and has 20 cc/min.cm2 or more of the air permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to friction materials such as disc brake pads and brake linings used for braking automobiles, railway vehicles, various industrial machines and the like.

[0002]

2. Description of the Related Art Friction materials such as disc brake pads and brake linings are used for braking automobiles, railway cars, various industrial machines and the like. Currently used disc brake pads are braked by using a fibrous substance such as aramid fiber or mineral fiber, a friction modifier such as cashew dust or graphite as shown in JP-A-6-84525. Less brake squeal and noise
Disc brake pads based on Non-Asbestos-Organic (hereinafter referred to as NAO materials) are mainly used.

However, performance requirements for brakes in recent years tend to be more and more advanced, and the anti-fade characteristics of conventional NAO materials have been improved while further improving the noise and vibration characteristics such as brake squeal and abnormal noise during braking. There is a demand for improved performance such as wear resistance. However, in the conventional disk brake pad as described above, it is difficult to fully satisfy all the characteristics.

Until now, attempts have been made to adjust the pore structure and the amount of gas permeation in a disc brake pad by using a filler having a large particle size as means for achieving both the fade resistance and the wear resistance. However, the existing disc brake pads have insufficient air permeation or cannot sufficiently satisfy brake squeal in addition to fade resistance and wear resistance.

[0005]

The invention according to claims 1, 2, 3 and 4 has excellent fade resistance and sound and vibration characteristics,
It is another object of the present invention to provide a friction material with less decrease in wear resistance and shear strength.

[0006]

The present invention comprises at least one kind of fibrous substance and at least one kind of inorganic material and / or organic material having a maximum particle size of not less than 500 μm, and a part of these materials has a diameter of not less than 500 μm. The present invention relates to a friction material that forms a spherical lump having a diameter of 2 mm or more and / or a substantially spherical lump and has an air permeation of 20 cc / min · cm ² or more.

Further, according to the present invention, an inorganic material having a maximum particle size of 500 μm or more comprises vermiculite and
An organic material having a size of 0 μm or more relates to a friction material that is cashew dust. Further, the present invention relates to a friction material in which the fibrous substance is contained in the entire composition in an amount of 4% by volume or more. further,
The present invention provides an inorganic material having a maximum particle size of 500 μm or more and / or
Alternatively, the present invention relates to a friction material in which an organic material contains at least 10% by volume of the entire composition.

[0008]

Air permeation quantity of the friction material according to the present invention DETAILED DESCRIPTION OF THE INVENTION, 20cc / min · cm ² or more, preferably 25cc / min · cm ² or more, more preferably in the range of 30~400cc / min · cm ² If it is less than 20 cc / min · cm ² , the fade resistance and the sound and vibration characteristics deteriorate.

Further, the friction material according to the present invention must contain at least one kind of inorganic and / or organic material having a maximum particle size of 500 μm or more, preferably 600 μm or more, and more preferably 700 to 1500 μm. When the inorganic material and / or the organic material have a maximum particle size of less than 500 μm, it is difficult to increase the air permeation amount to 20 cc / min · cm ² or more, and the fade resistance is deteriorated.

The content of the inorganic material and / or organic material having a maximum particle size of 500 μm or more is preferably 10% by volume or more, more preferably 12% by volume or more in the whole composition.
A range of 30% by volume is more preferable. If it is less than 10% by volume, the fade resistance tends to deteriorate. In addition, it is preferable to use vermiculite as the inorganic material having a maximum particle size of 500 μm or more.
Graphite or the like can be used. On the other hand, when the maximum particle size is 500
It is preferable to use cashew dust as the organic material having a size of μm or more, and rubber dust can also be used.

In the friction material according to the present invention, a fibrous substance and a part of an inorganic material and / or an organic material having a maximum particle diameter of 500 μm or more contain a diameter of 2 mm or more, preferably 2.5 mm or more.
As described above, it is more preferable to contain a spherical mass and / or a substantially spherical mass having a size of 3 to 7 mm and a diameter of 2 to 7 mm.
If it is less than mm or if it does not contain a spherical lumps and / or substantially spherical lumps, the fade resistance and the sound and vibration characteristics deteriorate.

The content of the fibrous substance in the total composition is preferably 4% by volume or more, more preferably 5% by volume or more.
The range of -20% by volume is more preferable. If it is less than 4% by volume, it is difficult to secure an air permeation amount, and the fade resistance and the sound and vibration characteristics tend to deteriorate, and the wear resistance and the shear strength tend to decrease.

In the present invention, the spherical mass refers to a mass having a substantially spherical shape, and the substantially spherical mass refers to a mass having an outer diameter which is generally spherical but has irregularities on the surface or a slightly square shape. Refers to a lump with a shape close to or a little closer to an ellipse.

In the present invention, the air permeation amount is determined by preparing a friction material piece having a thickness of 5 ± 0.2 mm from the obtained friction material, and connecting an air supply pipe (a predetermined area) to one surface of the friction material piece. When compressed air of 490 KPa at normal temperature is supplied to the friction material pieces so as not to leak from the pressed part of the air supply pipe,
It can be determined by measuring the amount of permeation (air permeation amount) into the air receiving pipe (the same area as the air supply pipe) on the opposite side of the friction material piece.

As the material used for the friction material of the present invention, generally known materials are used, for example, brass fiber, copper fiber, bronze fiber, zinc fiber, aramid fiber, acrylic fiber, carbon fiber, ceramic fiber, rock wool, Fibrous substances such as potassium titanate fiber, calcium carbonate whisker, magnesium carbonate whisker, phenolic resin, epoxy resin, melamine resin and their various modified resins (cashew modified, rubber modified, etc.), NBR, SBR, BR, IR, etc. Binder containing rubber composition, cashew dust (one kind of organic material used in the present invention), friction modifier such as antimony trisulfide, molybdenum disulfide, graphite, coke, alumina,
Friction enhancing agents such as silica, zirconia, zircon sand, silicon carbide, mullite, iron oxide, magnesia, titania, wollastonite, barium sulfate, calcium carbonate, magnesium carbonate, vermiculite (a kind of inorganic material used in the present invention) ), Fillers such as rubber powder and, if necessary, metal powders such as copper, brass, zinc, bronze, phosphor bronze and the like.

The content of the binder other than the fibrous substance is preferably 5 to 20% by volume, more preferably 7 to 18% by volume in the whole composition from the viewpoint of moldability and the like. , 9 to 16% by volume. The content of the friction modifier containing cashew dust is 5 to 40 in the total composition in view of the coefficient of friction and its stability.
%, More preferably 7 to 35% by volume, even more preferably 10 to 30% by volume. The content of the friction enhancer is preferably 1 to 30% by volume, more preferably 3 to 25% by volume, and more preferably 5 to 20% by volume in the whole composition from the viewpoint of the friction coefficient and other performance balance. % Is more preferable.

The content of the filler containing vermiculite is 5 to 60% by volume in the total composition in view of the packing density and the like.
Is preferably set to 8 to 50% by volume, and more preferably to 10 to 40% by volume. Furthermore, the content of the metal powder to be added as necessary is
The content is preferably 1 to 10% by volume in the whole composition,
-7% by volume, more preferably 3-6% by volume. These components are blended so that the total composition becomes 100% by volume. In the present invention, the volume% of each component is a value calculated by dividing the used weight of the component by the density of the component.

The friction material according to the present invention is obtained by uniformly mixing a fibrous substance, a binder, a friction modifier, a friction enhancer, a filler, and the like.
This mixture is preformed into a predetermined shape, and then the backing metal and the preformed body are inserted into a mold, and then molded by a heat and pressure molding method or a normal temperature and pressure molding method, and then subjected to a heat treatment. . After heat treatment if necessary, further 400 to 700
The surface of the molded body may be baked at a high temperature of ° C. The heating temperature at the time of molding is preferably 130 to 200 ° C, and 140 to 200 ° C.
190 ° C. is more preferred. The pressure is preferably from 10 to 50 MPa, more preferably from 20 to 40 MPa. The heat treatment temperature is preferably 150 to 300 ° C, and 180 to 250 ° C.
Is more preferred.

[0019]

The present invention will be described below with reference to examples.

Examples 1 to 4 and Comparative Examples 1 to 5 Among the components shown in Tables 1 and 2, B, C, I, K,
After blending the L and M components and pre-kneading with a mixer,
All the remaining components were added to the kneaded material and further mixed to obtain a friction material composition. Next, after preforming the friction material composition into a predetermined shape, the back metal and the preformed body obtained above are inserted into a mold, and heated and pressed at 140 ± 5 ° C. and a pressure of 20 MPa for 3 minutes. Further, a heat treatment was carried out at 250 ° C. for 4 hours, followed by cooling and polishing to obtain a disc brake pad.

[0021]

[Table 1]

[0022]

[Table 2]

Next, a comparative test was performed on the disc brake pad of the embodiment according to the present invention and the disc brake pad of the comparative example. Table 3 shows the test results. The test conditions are as follows.

Coefficient of friction (μ) A dynamo test was performed according to JASO C402, and the coefficient of friction was compared. Brake squeal An actual vehicle test was performed in accordance with JASO C402, brake squeal during the test was measured, and the occurrence rate of brake squeal of 75 dB or more was determined.

Pad Wear The thickness of the pad was measured before and after the effect / fade test, and the wear amount was compared based on the difference in the thickness. Shear force Shear force was measured according to JASO C427.

[0026]

[Table 3]

As shown in Table 3, the disc brake pad according to the embodiment of the present invention has excellent anti-fade characteristics, is sufficiently effective, has a low brake squealing rate, has excellent sound and vibration characteristics, and has pad wear. It can be seen that there is little and the shearing force is strong. On the other hand, the disc brake pads of Comparative Examples 1 to 5 have insufficient fade resistance and a high rate of brake squeal. In particular, the disc brake pads of Comparative Example 5 have fade resistance, brake squeal and pad wear. , And the shearing force are all inferior.

[0028]

The friction material according to the first, second, third and fourth aspects is excellent in fade resistance and sound and vibration resistance, and has little reduction in wear resistance and shear strength, and is extremely suitable for industrial use.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/14 520 C09K 3/14 520M

Claims (4)

[Claims] Claims: 1. An article comprising one or more kinds of fibrous substances and one or more kinds of inorganic materials and / or organic materials having a maximum particle size of 500 μm or more, and a part of these materials is a spherical mass having a diameter of 2 mm or more and / or A friction material that forms a substantially spherical mass and has an air permeation amount of 20 cc / min · cm ² or more. 2. The friction material according to claim 1, wherein the inorganic material having a maximum particle size of 500 μm or more is vermiculite and the organic material having a maximum particle size of 500 μm or more is cashew dust. 3. The friction material according to claim 1, wherein the fibrous substance is contained in the total composition in an amount of 4% by volume or more. 4. The friction material according to claim 1, wherein the inorganic material and / or the organic material having a maximum particle size of 500 μm or more are contained in the entire composition in an amount of 10% by volume or more.