JP2005247898A - Friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction material capable of effectively aiming at various properties including coefficient of friction, abnormal noise and rotor attacking tendency. <P>SOLUTION: The friction material 1 consists mainly of a fiber base, a binder and friction regulators, wherein an abrasive 2 is contained in a granulated condition in this friction material as one of the friction regulators. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to friction materials such as brake pads and brake linings for automobiles and the like, and in particular, friction mainly containing a fiber base material, a binder, and a friction modifier, and including friction as one of the friction modifiers. Regarding materials.

The friction material is required to have various characteristics. For example, various characteristics such as friction coefficient, abnormal noise, and aggressiveness to the rotor are required. Various developments have been made in the past to satisfy various characteristics, and the friction materials described in Patent Documents 1 and 2 have been conventionally introduced.
The friction material described in Patent Document 1 includes a fiber base material, a binder, and a friction modifier as main components. Two types of abrasives are included as friction modifiers. One is a large and soft abrasive and the other is a small and hard abrasive. The reason for using a large abrasive was to scrape off the coating and rust generated on the rotor, and to reduce vibration and noise by removing the coating and rust. The reason for using soft abrasive was to reduce the aggressiveness of the rotor. On the other hand, the reason for using a small and hard abrasive was to improve the friction coefficient.
The friction material described in Patent Document 2 is also mainly composed of a fiber base material, a binder, and a friction modifier. As a friction modifier, hard abrasives having different particle sizes were included. The reason for this configuration is to increase the difference in the amount of wear of the rotor between the bottom surface pressure and the high surface pressure on the rotor, and to aim at preventing uneven wear of the rotor.
JP 2001-310771 A JP 2003-206474 A

However, the friction materials according to Patent Documents 1 and 2 tend to be dominated by the large particle size abrasive. For this reason, there are not a few cases where the targeted characteristics cannot be obtained sufficiently due to the small particle size.
Then, this invention makes it a subject to provide the friction material which can aim at various characteristics, such as a friction coefficient, abnormal noise, and the attack property to a rotor effectively.

In order to solve the above-described problems, the present invention is a friction material having a configuration as described in each claim.
According to the first aspect of the present invention, the abrasive is contained in a granulated state.
Therefore, when the friction material is pressed against a mating material such as a rotor, the abrasive is first pressed against the mating material in a granulated state. And by pressing strongly, a granulation state collapses and it changes to the state before granulation.
Therefore, the friction material has a configuration that can easily exhibit both the characteristics of the abrasive after granulation and the characteristics of the particle diameter before granulation. Thus, the friction material can easily aim at various characteristics by adjusting the particle size before the granulation of the abrasive and the particle size after the granulation.

According to the invention described in claim 2, the abrasive granulates a powder having a Mohs hardness of 7 or more and a particle size of 0.1 μm or more and 10 μm or less into a granulated body having a particle size of 50 μm or more and 1 mm or less. It is included in the state.
That is, the abrasive is made into a granulated body of a necessary size by using a hard and small powder as a raw material and granulating the powder.
Therefore, the abrasive is first pressed against a mating member such as a rotor in the state of a granulated body. And the particle size of a granulation body is 50 micrometers or more and 1 mm or less. Therefore, the granulated body is sufficiently large to scrape off the coating film and rust generated on the rotor, and vibration and noise can be reduced by scraping off the coating film and rust.

Further, the abrasive granulated body is strongly pressed against the counterpart material, and the granulated state collapses to change to a powder before granulation. The particle size of the powder is not less than 0.1 μm and not more than 10 μm, and is small enough not to make a major attack on the counterpart material. Further, since the powder has a Mohs hardness of 7 or higher, the friction coefficient of the friction material can be increased.
Thus, the friction material is configured to easily improve various characteristics (abnormal noise, aggressiveness to the rotor, friction coefficient).
The Mohs hardness is the Mohs hardness when the diamond is 10.

According to invention of Claim 3, the granulated abrasive is contained 1 volume% or more and 30 volume% or less of the whole friction material.
Thereby, the friction material has a configuration capable of obtaining appropriate characteristics.

The friction material according to the present invention has a fiber base material, a binder, and a friction modifier as main components.
As the fiber substrate, inorganic fibers and organic fibers can be appropriately selected and used. Examples of the inorganic fibers include steel fibers, copper fibers, glass fibers, ceramic fibers, and potassium titanate fibers. Moreover, an aramid fiber etc. are mentioned as an organic fiber. These fiber base materials can be used individually, but several types can also be mixed and used.
Moreover, the fiber base material is used in the short fiber form and the powder form, and it is preferable that the addition amount of a fiber base material is 10-50 volume% of the whole friction material.

As the binder, for example, phenol resin, imide resin, rubber-modified phenol resin, melamine resin, epoxy resin, NBR, nitrile rubber, acrylic rubber and the like are used. And a binder can also be used individually by 1 type, and can also be used in combination of 2 or more type.
Moreover, it is preferable that the addition amount of a binder is 5-30 volume% of the whole friction material.

The friction modifier is included for adjusting a friction coefficient, adjusting abnormal noise, preventing rust, and the like, and appropriately includes an inorganic filler, an organic filler, a lubricant, and the like.
As the inorganic filler, abrasive, barium sulfate, calcium carbonate, calcium hydroxide, mica (mica), kaolin, talc and the like can be used. As the organic filler, cashew dust or rubber dust can be used. As the lubricant, graphite (graphite), antimony trisulfide, molybdenum disulfide, zinc disulfide and the like can be used.
These friction modifiers can be used singly or in combination of two or more.

Further, in this embodiment, an abrasive of an inorganic filler is necessarily included as one of the friction modifiers. And the contained abrasive is contained in the granulated state.
The abrasive before granulation is a powder having a Mohs hardness of 7 or more and less than 10. For example, it is a powder made of zirconium silicate (Mohs hardness 7.5), zirconium oxide (Mohs hardness 7.5), silicon carbide (Mohs hardness 9), silica (Mohs hardness 7) and alumina (Mohs hardness 9).
The particle size of the powder is preferably a small particle size in order to reduce the aggressiveness to the counterpart material such as the rotor, and is preferably 0.1 μm or more and 10 μm or less, for example.
Abrasive powders can be used alone or in combination of two or more. The Mohs hardness is a hardness according to a measurement method when diamond is 10.

Abrasive powder is granulated by a granulating apparatus. That is, in the abrasive, a plurality of powders are solidified into a lump-like granulated body having a predetermined particle size by a granulating binder.
As the granulation method, a rolling granulation method, an extrusion granulation method, a compression granulation method, a melt granulation method, or the like can be used. As a binder, organic substances, such as a phenol resin and a polyimide resin, metals, such as copper and zinc, inorganic substances, such as glass, etc. can be used.

The particle size of the abrasive granule is preferably large enough to scrape off the coating or rust generated on the rotor or the like, and is preferably 50 μm or more, for example. Further, the particle size of the granulated body is preferably 1 mm or less in order to improve the dispersibility of the granulated material in the friction material.
The binding force between the powders by the binder is strong enough to scrape off the coating or rust generated on the rotor or the like. And it is sufficiently stronger than the binding force of the other part of the friction material, for example, the fiber base material. Accordingly, the abrasive granule can sufficiently scrape the coating and rust generated on the rotor and the like from the rotor and the like.

Further, the binding force between the powders by the binder is weaker than the abrasive powder alone to such an extent that the granulated body becomes brittle. Therefore, the granulated body can be broken by being strongly pressed against the rotor. That is, when the powder is peeled off from the binder to which the powder is bonded, the granulated body changes to the state before granulation. Therefore, the granulated body is configured to be able to collapse before the rotor is severely damaged.
Moreover, it is preferable that the addition amount of an abrasive granule is 1 volume% or more and 30 volume% or less of the whole friction material. This is to prevent the friction coefficient from being excessively small when the amount is too small, and to prevent the friction coefficient from being excessively large when the amount is too large.

Next, the manufacturing method of a friction material is demonstrated according to FIG.
First, an abrasive powder is granulated into a granulated body (step S1).
And an abrasive granule, another friction modifier, a fiber base material, and a binder are mixed uniformly using a mixer, and a raw material mixture is obtained (step S2). As the mixer, for example, a Henschel mixer, a Redige mixer, an Eirich mixer, or the like is used.
Next, the raw material mixture is preformed with a molding die, and the preform is molded at a molding temperature of 130 to 200 ° C. and a molding pressure of 100 to 1000 kg / cm ^{2 for 2 to} 15 minutes (step S3).
Subsequently, the obtained molded product is heat-treated (post-cured) for 2 to 48 hours at 140 to 250 ° C. (step S4). Then, the finished product of the friction material is obtained by performing spray coating, baking, and polishing treatment as necessary.

Next, a braking state when the friction material 1 is pressed against a counterpart material such as the rotor D will be described with reference to FIGS. In particular, the braking state in the abrasive will be described.
The friction material 1 has an abrasive granule 2 as shown in FIG. The granulated body 2 is obtained by granulating the powder 3.
On the surface of the rotor D, the coating 4 and the rust 5 are likely to be generated. When the friction material 1 is pressed toward the rotor D, the granulated body 2 first hits the coating 4 or rust 5. This is because the granulated body 2 has a large particle size and protrudes greatly to the rotor D side. Therefore, the granulated body 2 can sufficiently scrape the coating 4 and the rust 5 from the rotor D.

When the friction material 1 is strongly pressed against the rotor D, the granulated body 2 is broken by the friction force generated between the friction material 1 and the rotor D as shown in FIG. And it will change to the powder 3 of the state before granulation by collapsing. And since the powder 3 has a small particle diameter, the rotor D is not damaged greatly. That is, the friction material 1 has a configuration that is less aggressive to the rotor D.
The abrasive powder 3 has a high hardness (Mohs hardness of 7 or more). Therefore, the friction material 1 has a high friction coefficient due to the hardness of the powder 3 and has a configuration excellent in braking performance.

(Example)
Below, specific Examples 1-3 of this invention and Comparative Examples 1-3 for comparing them are demonstrated.
Each friction material of Examples 1-3 and Comparative Examples 1-3 is shape | molded from the raw material mixture which mix | blended the raw material shown in Table 1. FIG.
The friction material according to Example 1 contains 15% by volume of an alumina abrasive granule. The granulated body is obtained by granulating alumina powder having a particle diameter of 1 μm to a particle diameter of 100 μm.
The friction material according to Example 2 contains 5% by volume of abrasive granulates of silicon carbide. The granulated body is obtained by granulating silicon carbide powder having a particle size of 5 μm to a particle size of 300 μm.
The friction material according to Example 3 contains 30% by volume of zirconia abrasive granules. The granulated body is obtained by granulating zirconia powder having a particle size of 10 μm to a particle size of 500 μm.

On the other hand, the friction material according to Comparative Example 1 contains 15% by volume of an alumina abrasive granule. The granulated body is obtained by granulating alumina powder having a particle diameter of 1 μm to a particle diameter of 20 μm. That is, it is a friction material in which the particle size of the granulated material after granulation is smaller than that of Example 1.
The friction material according to Comparative Example 2 contains 15% by volume of alumina abrasive. Abrasives are not granulated and have a particle size of 100 μm.
The friction material according to Comparative Example 3 contains 35% by volume of an alumina abrasive granule. The granulated body is obtained by granulating alumina powder having a particle diameter of 1 μm to a particle diameter of 100 μm. That is, the friction material has a larger amount of abrasive granules than in Example 1.

And each raw material which consists of the compounding quantity shown in Table 1 was mixed uniformly for 5 minutes using the Eirich mixer, and the raw material mixture was obtained (FIG. 3, step S2). The raw material mixture was put into a mold heated to 160 ° C., and pressed for 10 minutes at 200 kg / cm ² to obtain a molded body having a predetermined shape (FIG. 3, step S3). And the molded object was hardened at 230 degreeC for 3 hours (FIG. 3, step S4), and the brake pad for passenger cars was obtained by this.

Next, the characteristics of the friction materials of Examples 1 to 3 and Comparative Examples 1 to 3 were measured, and the results are summarized in Table 2.
Each characteristic was measured as follows.
<Friction coefficient> Under the usual effectiveness test (JASO C 406-87 “passenger car brake device dynamometer test method” compliant), the average friction coefficient is determined at a braking initial speed 50 km / h and deceleration 0.35 g or less in the final effectiveness test. It was measured.
<Rotor Attack Amount> The amount of wear of the rotor after a drag test for 24 hours with a pressure of 0.1 MPa applied to the rotor rotating at a speed of 80 km / h was measured.
<Anomalous noise> An evaluation test using an actual vehicle was performed.
<Dispersed state> The distribution state of the granulated material on the surface of the brake pad (friction material) was visually measured with a microscope.

The following was found from the measurement results in Table 2.
From the results of Examples 1 to 3, the brake pads according to Examples 1 to 3 can obtain a desired braking force (friction coefficient), a desired rotor aggressiveness, a desired abnormal noise characteristic, and a desired dispersibility. all right.
Moreover, from the result of the comparative example 1, it turned out that the noise characteristic of the brake pad which concerns on the comparative example 1 is not good. The cause was found to be due to the small particle size of the granulated body. That is, the abrasive granule according to Comparative Example 1 has a smaller particle size than that of Example 1. Therefore, it was found that the granulated body according to Comparative Example 1 could not sufficiently scrape the coating and rust generated on the rotor, and it was considered that abnormal noise was generated due to the coating and rust.

Moreover, it turned out that the attack amount of the rotor of the brake pad which concerns on the comparative example 2 is large from the result of the comparative example 2. The cause was found to be because the abrasive was not granulated. That is, the abrasive according to Comparative Example 2 is different from the abrasive according to Example 1 in that it is not granulated. The particle size is the same. Therefore, it was found that the abrasive according to Comparative Example 2 attacked the rotor greatly because it was not granulated.
Further, from the results of Comparative Example 3, it was found that the characteristics of the brake attack amount, abnormal noise characteristics, and dispersibility of the brake pad according to Comparative Example 3 were slightly poor. And the cause was understood to be because there are many compounding quantities of a granulated body.

The friction material according to the present invention is configured as described above.
That is, the abrasive contained in the friction material is contained in a granulated state as shown in FIGS.
Therefore, when the friction material 1 is pressed against a counterpart material such as the rotor D, the abrasive is first pressed against the counterpart material in a granulated state. And by pressing strongly, a granulation state collapses and it changes to the state before granulation.
Therefore, the friction material 1 has a configuration that can easily exhibit both the characteristics of the abrasive after the granulation and the characteristics of the grain before the granulation. Thus, the friction material 1 can easily aim at various characteristics by adjusting the particle size before the granulation of the abrasive and the particle size after the granulation.

The abrasive is made into a granulated body 2 having a required size by using a hard and small powder 3 as a raw material and granulating the powder 3.
Accordingly, the abrasive is first pressed against the mating material such as the rotor in the state of the granulated body 2. And the particle size of the granulation body 2 is 50 micrometers or more and 1 mm or less. Therefore, the granulated body 2 has a sufficient size to scrape off the coating 4 and rust 5 generated on the rotor D, and vibration and noise can be reduced by scraping off the coating 4 and rust 5.

Further, the abrasive granule 2 is strongly pressed against the rotor D as shown in FIG. The particle diameter of the powder 3 is not less than 0.1 μm and not more than 10 μm, and is small enough not to make a big attack on the rotor D. In addition, since the powder 3 has a Mohs hardness of 7 or more and is hard, the friction coefficient of the friction material 1 can be increased.
Thus, the friction material 1 is configured to easily improve various characteristics (abnormal noise, aggressiveness to the rotor, friction coefficient).
The granulated abrasive is contained in an amount of 1% by volume to 30% by volume of the entire friction material. Thereby, the friction material 1 has a configuration capable of obtaining appropriate characteristics.

It is the friction material for showing a mode that an abrasive granule scrapes off the film and rust which generate | occur | produced in the rotor, and the partial side surface enlarged view of a rotor. It is a partial side surface enlarged view of the friction material and rotor for showing a mode that an agglomerated granule collapses and becomes powder. It is a manufacturing-process figure of a friction material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Friction material 2 ... Abrasive granule 3 ... Abrasive powder 4 ... Coating 5 ... Rust D ... Rotor

Claims (3)

A friction material mainly composed of a fiber base material, a binder, and a friction modifier, and containing abrasive as one of the friction modifiers,
A friction material comprising the abrasive in a granulated state. The friction material according to claim 1,
Abrasive is included in a state where a powder having a Mohs hardness of 7 or more and a particle size of 0.1 μm or more and 10 μm or less is granulated into a granulated body having a particle size of 50 μm or more and 1 mm or less. Friction material characterized by The friction material according to claim 1 or 2,
A friction material, wherein the granulated abrasive is contained in an amount of 1 to 30% by volume of the entire friction material.

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