JP2008143937A - Non-asbestos-based friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a friction material for a brake, which has an environmental loading lower than that of a friction material using an antimony compound, an excellent high-temperature abrasion resistance, a low aggresiveness to a mating material and retains a high coefficient of friction. <P>SOLUTION: The non-asbestos-based friction material contains no antimony compound as the compounding material of a friction material and comprises 1-20 mass% of a composite material obtained by inserting metal oxide particles into the interlayers of a layered clay mineral. The weight ratio of the metal oxide/layered clay mineral of the composite material is 0.1-2.0, the layered clay mineral is synthetic fluorine mica and the metal oxide is preferably a titania particle and an alumina particle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-asbestos friction material that does not use an antimony compound, and more particularly to a friction material that suppresses rotor aggression and has improved fade characteristics used in industrial machinery, railway vehicles, luggage vehicles, passenger cars, and the like. In particular, it relates to a friction material that can ensure high-temperature wear resistance without using an antimony compound, and that keeps a high coefficient of friction while keeping the other material's aggressiveness low. Relates to brake pads, brake linings, and clutch facings used in the aforementioned applications.

  Friction materials used in brakes such as disc brakes and drum brakes, or clutches, etc., provide a frictional effect and adjust the friction performance, a fiber base material that reinforces, and these components are integrated. It is made of materials such as binding material. There are various types of fiber base materials, such as metal fibers, inorganic fibers, and organic fibers. Each type has its own characteristics, and since one type cannot satisfy all requirements, usually two or more types are combined. Has been used.

  On the other hand, there are friction modifiers and solid lubricants as materials that adjust the friction characteristics of friction materials, but these also have inorganic and organic types, each with their own characteristics. One type satisfies all requirements. In general, two or more types are used in combination. Examples of friction modifiers include inorganic friction modifiers such as alumina, silica, magnesia, and zirconia; organic friction modifiers such as synthetic rubber and cashew resin; and solid lubricants such as graphite and molybdenum disulfide. Can be mentioned.

As the filler, barium sulfate, calcium carbonate, metal powder, vermiculite, mica, and the like are used.
In addition, friction materials of various blends have been proposed as non-asbestos-based friction materials that suppress the attack of the friction material containing these components and improve the fade resistance and wear resistance.

Patent Document 1 discloses a brake friction material with reduced brake noise used for automobiles and the like, in particular, as a brake friction material that does not generate low-frequency noise when starting an automatic vehicle, a reinforcing fiber, a friction adjusting material, a lubricant, and Friction material comprising a binder, brake friction material containing 2-5% by mass of zeolite, 0.8-2% by mass of antimony oxide and 0.2-1% by mass of fluoropolymer as part of the friction modifier component Is disclosed.
JP 2001-181607 A

However, the brake friction material disclosed in Japanese Patent Application Laid-Open No. 2001-181607 has a drawback in that fade resistance decreases when the antimony oxide content exceeds 2 mass%.
In addition, antimony compounds do not contain antimony because they are designated substances in the PRTR Law (Act on Understanding the Release of Specific Chemical Substances into the Environment and Promoting Improvements in Management) established from the viewpoint of environmental protection. Materials that have lubricity at high temperatures and can adjust friction characteristics have been demanded.

  The present invention has been made under such conventional circumstances, and has a lower environmental load than a friction material using an antimony compound, excellent high-temperature wear resistance, low opponent attack, and maintains a high coefficient of friction. An object of the present invention is to provide a friction material for a brake.

  The inventors of the present invention have continued intensive research to achieve the above-mentioned object, and friction adjustment is performed on the raw material of the friction material using a composite material in which metal oxide particles are inserted between layers of layered clay mineral such as synthetic mica. Paying attention to the fact that by blending an appropriate amount as part of the material, wear resistance at high temperatures can be ensured without using an antimony compound, while maintaining a high coefficient of friction and keeping the other material aggressive. The present invention has been reached.

That is, the present invention has solved the above problems by the following means.
(1) A non-asbestos system containing 1 to 20% by mass of a composite material containing no antimony compound and having metal oxide particles inserted between layers of a layered clay mineral as a blending material of a friction material Friction material.
(2) The non-asbestos friction material according to (1) above, wherein the composite material has a metal oxide / layered clay mineral mass ratio of 0.1 to 2.0.
(3) The non-asbestos friction material according to (1) or (2) above, wherein the layered clay mineral of the composite material is synthetic fluorine mica.
(4) The non-asbestos friction material according to any one of (1) to (3), wherein the metal oxide particles of the composite material are titania particles.
(5) The non-asbestos friction material according to any one of (1) to (3), wherein the metal oxide particles of the composite material are alumina particles.

  According to the present invention, in a non-asbestos-based friction material made of a reinforcing fiber base material, a friction adjusting material, a binding material that integrates these components, etc., as a part of the friction adjusting material, between the layers of the layered clay mineral By using a composite material in which metal oxide particles are inserted, the amount of wear when sliding at a high temperature of 300 ° C. or higher can be reduced without using an antimony compound that is problematic from the viewpoint of environmental protection, and friction can be reduced. The coefficient of friction when the material slides at a high temperature of 300 ° C. or higher can be increased, and at the same time, wear of the counterpart material can be suppressed.

Embodiments of the present invention will be described below.
In the non-asbestos-based friction material of the present invention, 1 to 20% by mass of a composite material in which metal oxide particles are inserted between layers of a layered clay mineral, with the friction material as a part of the friction modifier. Thus, the friction and wear performance when the non-asbestos friction material slides at a high temperature of 300 ° C. or higher is made the same as that of the friction material using the antimony compound.

  If the blending amount is less than 1% by mass, the amount is too small and sufficient friction and wear performance at high temperatures cannot be exhibited. On the other hand, if it exceeds 20% by mass, further improvement in friction and wear performance cannot be achieved, which is uneconomical. Therefore, the appropriate content is 1 to 20% by mass.

In the present invention, as the layered clay mineral, for example, a natural clay mineral having an ion exchange ability such as kaolinite, smectite, vermiculite, or artificial synthetic clay is used. Examples of smectites include montmorillonite, saponite, hydelite, and nontronite. Among them, a synthetic fluorine mica having a small quality variation compared to a natural layered clay mineral is suitable for use in the present invention, and sodium tetrasilicon fluorine mica (NaM _2.5 Si ₄ O ₁₀ F ₂ ) is used. Illustrated.

In the present invention, the metal type of the metal oxide is preferably a metal having a property capable of being cationized, such as aluminum or titanium.
The weight ratio of the composite metal oxide / layered clay mineral is preferably 0.1 to 2.0.

In order to produce the friction material of the present invention, various materials for friction material consisting of a fiber base material, a friction modifier, a lubricant, a filler, and a binder are blended, and the blend is preformed according to a normal manufacturing method, It can be manufactured by thermoforming. In the above, examples of the fiber substrate include organic fibers such as aromatic polyamide fibers and flame-resistant acrylic fibers, copper fibers, metal fibers such as steel fibers, potassium titanate fibers, Al ₂ O ₃ —SiO ₂ ceramic fibers, and the like. Inorganic fiber. Examples of the inorganic filler include metal particles such as copper, aluminum and zinc, scaly inorganic materials such as vermiculite and mica, barium sulfate and calcium carbonate.

  Examples of the binder include thermosetting resins such as phenol resins (including various modified phenol resins such as straight phenol resins and rubbers), melamine resins, epoxy resins, and polyimide resins. Examples of the friction modifier include metal oxides such as alumina, silica, magnesia, zirconia, and chromium oxide; organic friction modifiers such as synthetic rubber and cashew resin; and solid lubricants such as graphite and molybdenum dioxide. Can be mentioned. As the composition of the friction material, various composition ratios can be adopted. That is, these may be blended singly or in combination of two or more according to the friction characteristics required for the product, for example, friction coefficient, wear resistance, vibration characteristics, squeal characteristics, and the like.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to only these examples.

Example 1 and Comparative Examples 1-3
<Titania particle insertion composite>
(Manufacture of composite materials)
20 g of synthetic fluorine mica was added to 2 liters of distilled water and stirred at room temperature for 24 hours. On the other hand, 56 g of tetraisopropoxysilane was added to 500 ml of an 80% aqueous solution of acetic acid, mixed at 50 ° C. for 1 hour, cooled to room temperature, and added to a synthetic fluoromica-dispersed aqueous solution. After mixing at room temperature for 2 hours, the sample was removed by centrifugation, washed with 2 liters of distilled water, and centrifuged until the pH reached 5 or more. The sample was depressurized at room temperature and dried for 72 hours, followed by heat treatment at 500 ° C. for 2 hours, and a pulverization process was performed to obtain a composite material in which titania particles were inserted between synthetic fluorine mica layers.
According to the above procedure, a composite material (sample A) in which 40% of titania particles were inserted between the layers of synthetic fluorine mica was obtained.
(Preparation of friction material sample)
A friction material was made with the formulation shown in Table 1 below. Moreover, the comparative material 1 and the comparative material 2 which mix | blended antimony sulfide or mica instead of the composite material sample were produced, and the thing which does not mix | blend a sample, antimony sulfide, or mica was produced as the comparative material 3.

(Friction test)
A friction test was conducted using the prototype friction material under the conditions shown in Table 2 below.
(Test results)
The test results of Example 1 and Comparative Examples 1 to 3 are shown in Table 3 below.
Since the wear amount in the 400 ° C. wear test of Example 1 is equivalent to that of Comparative Example 1 using an antimony compound, the effect of the present invention was confirmed.

Example 2 and Comparative Example 4
<Alumina particle insertion composite>
(Manufacture of composite materials)
24 g of aluminum chloride hydrate was dissolved in 500 ml of distilled water and stirred. An aqueous solution prepared by dissolving 10 g of sodium hydroxide in 2500 g of distilled water was added dropwise to the solution at 50 ml / min. After the dropwise addition, the mixture was refluxed at 95 ° C. for 48 hours. Wash with water in a centrifuge. A drying treatment was performed at 80 ° C. for 2 hours.
Further, a heat treatment was carried out in a heating furnace at 400 ° C. for 2 hours, and a composite material (sample B) in which alumina particles were inserted between mica layers through pulverization was obtained.
(Preparation of friction material sample)
Using the composite material synthesized as described above, a test piece was molded according to the formulation shown in Table 4, and the friction characteristics were then evaluated. At the same time, a friction material not containing the composite material (sample B) was produced, and this was designated as Comparative Example 4.

(Abrasion test)
A wear test was performed on test pieces molded with the formulations shown in Table 4.
In the wear test, the friction material wear amount (mm) and the disk rotor wear amount (g) were measured under the conditions of an initial braking speed of 50 km / h, a braking frequency of 200 times, and a braking brake temperature of 100 ° C. and 400 ° C.
(Test results)
The results are shown in Table 5 below.

  As is apparent from the results of the wear test shown in Table 5, the friction material of Example 2 has a higher coefficient of friction at 400 ° C. and a smaller amount of rotor wear than the friction material of Comparative Example 4. The excellent effect of using a composite material obtained by inserting metal oxide particles between layers of the layered clay mineral of the present invention as a part of the friction modifier was confirmed.

  In the non-asbestos friction material of the present invention, an appropriate amount of a composite material in which metal oxide particles are inserted between layers of a layered clay mineral such as synthetic mica is mixed as a part of the friction modifier in the raw material of the friction material. By this, it is possible to ensure wear resistance at high temperatures without using an antimony compound, and while maintaining a high coefficient of friction, it is possible to keep the opponent material attack low, especially industrial machinery, railway vehicles, luggage vehicles, It is particularly useful for friction materials such as passenger cars, more specifically, brake pads, brake linings, and clutch facings used in the above-described applications.

Claims (5)

  A non-asbestos-based friction material containing 1 to 20% by mass of a composite material that does not contain an antimony compound and is formed by inserting metal oxide particles between layers of a layered clay mineral as a blending material of the friction material.   2. The non-asbestos friction material according to claim 1, wherein the composite material has a metal oxide / layered clay mineral mass ratio of 0.1 to 2.0.   3. The non-asbestos friction material according to claim 1, wherein the layered clay mineral of the composite material is synthetic fluorine mica.   The non-asbestos friction material according to any one of claims 1 to 3, wherein the metal oxide particles of the composite material are titania particles.   The non-asbestos friction material according to any one of claims 1 to 3, wherein the metal oxide particles of the composite material are alumina particles.