JP2001311072A - Friction material composition and friction material produced by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction material composition suitable for a friction material enabling us to cope with lightening, to retain a reinforcing property and to obtain a stabilized friction coefficient, and to provide a friction material enabling us to cope with lightening, to retain a reinforcing property and to obtain a stabilized friction coefficient. SOLUTION: This friction material composition comprises a shape memory alloy in an amount of 1-40 wt.% based on the total weight of the composition. The friction material is produced by the hot pressure forming of the friction material composition. For example, the shape memory alloy is produced by forming an alloy such as a Ti-Ni alloy exhibiting thermo-elastic martensitic transformation and returning to a shape before being deformed by being heated at >=100 deg.C into a pine cone-like shape having fine splits.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material composition suitable for a friction material such as a disc brake pad and a brake lining used for braking automobiles, railway vehicles, various industrial machines and the like, and a friction material composition. Related to friction material.

[0002]

2. Description of the Related Art Friction materials such as disc brake pads and brake linings are used in automobiles, railway vehicles, various industrial machines and the like for braking. Conventionally, as this friction material, a semi-metallic friction material containing steel fibers as a main constituent fiber was mainly used as disclosed in JP-A-64-87930, JP-A-2-17985, etc. As the industry shifts to lighter and more sophisticated vehicles, problems such as abnormal noise when starting and stopping automatic vehicles (generation of noise), insufficient braking power at low temperatures, and wheel contamination due to abrasion powder are increasing. Came out.

[0003] In order to solve these problems, non-ferrous metal fibers such as copper fiber and brass fiber are used instead of steel fiber.
The transition to non-steel friction materials using organic fibers and inorganic fibers such as aramid fibers and ceramic fibers, as well as inorganic materials, has rapidly progressed. Further, conventionally, as the fuel economy and the transition to electric vehicles have progressed, weight reduction has been required, and it has become necessary to reduce the weight fundamentally in order to solve the above problems.

In the prior art, the strength has been reinforced with inorganic fibers, organic fibers, metal fibers, etc., but as the weight is reduced, the absolute amount of metal is reduced, the reinforcing property is maintained, and a stable friction coefficient is maintained. At present, a friction material capable of obtaining (μ ≧ 0.30) has not been obtained.

[0005]

SUMMARY OF THE INVENTION According to the first and second aspects of the present invention, a friction material composition suitable for a friction material capable of maintaining a reinforcing property and achieving a stable friction coefficient in response to weight reduction. It provides things. The third aspect of the present invention is to provide a friction material capable of coping with weight reduction, maintaining a reinforcing property, and obtaining a stable friction coefficient.

[0006]

The present invention relates to a friction material composition comprising 1 to 40% by weight of a shape memory alloy in the whole composition. Further, the present invention relates to a method for manufacturing a shape memory alloy, comprising:
The present invention relates to a friction material composition that is a thermoelastic martensitic transformation alloy that returns to a shape before being deformed at a temperature of not less than ° C. Further, the present invention relates to a friction material obtained by heating and pressing the above friction material composition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the shape memory alloy means an alloy having a property that, when apparently undergoing plastic deformation, when heated, returns to the shape before deformation as if it had been memorized. Is what you do.

The thermoelastic martensitic transformation is
There are atomic arrangements in metals, that is, several states with different crystal structures (this is called a phase). The phase transformation that occurs when the composition, temperature, or pressure of the constituent metal elements changes is called martensitic transformation. The martensitic transformation in which the equilibrium state between the thermal effect of reducing the free energy of energy and the elastic effect of increasing the non-chemical free energy is maintained throughout the transformation is called thermoelastic.

[0009] The content of the shape memory alloy is 1 in the total composition.
The range is from about 40% by weight, preferably from 1 to 20% by weight, and more preferably from 1 to 10% by weight. If it is less than 1% by weight, a stable friction coefficient (μ ≧ 0.30) cannot be obtained. On the other hand, if it exceeds 40% by weight, noise (70 dB)
The above-mentioned sound pressure) cannot be suppressed, and the weight cannot be reduced.

As the shape memory alloy, 100 ° C. or more, preferably 120 ° C. or more, more preferably 130 to 20 ° C.
It is preferable to use a thermoelastic martensitic transformation alloy that returns to a shape before being deformed by heating at a temperature of 0 ° C. Examples of such an alloy include Ti—Ni and Cu.
It is preferable to use -Zn-Al, Cu-Al-Ni, or the like. Shape memory alloy is 2-5mm in diameter and 5-5mm in length
It is preferable to use an alloy in the range of 50 mm because the alloy has excellent reinforcing properties, and in particular, the shear strength can be increased to the target value of 20000 (N) or more.

[0011] The shape memory alloy of the present invention, by cutting the surface of the alloy shown above in the same direction with a cutting machine, to produce a sag,
Then, heat (shape memory processing) to float the ends of the pines as if the pine cone had opened, and then apply a load to the outer periphery once at room temperature to deform the floating parts so that they would adhere to the surface. This is used as one component of the friction material composition before molding. The above-mentioned sprinkle does not float at normal temperature, but floats at the time of hot press molding, and has an effect of retaining the reinforcing properties as a friction material.

There are no particular restrictions on the length and width of the burrs, but for example, the length is preferably larger than the diameter of the shape memory alloy, and more preferably twice or more the diameter. The width is 0.5 to 2.5 mm
Is preferably within the range.

The target value of the noise in the present invention is JAS
An actual vehicle test of OC402 was performed, and abnormal noise during the test was measured. The number of times of generation of sound pressure of 70 dB or more was 20 or less out of 2850 times.

In the friction material composition of the present invention, a binder, a reinforcing fiber, a lubricant, a filler, a grinding agent and the like are used in addition to the shape memory alloy. If necessary, a metal powder such as brass and bronze is used. Used.

The binder used in the present invention includes phenol resins, epoxy resins, melamine resins and the like. Of these, phenol resins are preferable, and in particular, novolak resins, solid ammonia resole resins, silicon-modified phenol resins, acrylic resins It is preferable to use a rubber-modified phenol resin.

In the present invention, a curing agent is added to the above binder, if necessary. The binder is preferably contained in the entire composition in an amount of 5 to 20% by weight from the viewpoint of moldability and the like, and 8 to 14% by weight.
More preferably, it is contained by weight. Further, as a curing agent added as needed, hexamethylenetetramine, paraformaldehyde, trioxane, or the like is used, and the content is preferably 8 to 14% by weight in the binder,
More preferably, the content is 12% by weight.

Examples of the reinforcing fibers include inorganic fibers such as glass fibers, ceramic fibers, carbon fibers, and mineral fibers; organic fibers such as aramid fibers, polyamide fibers, and polyimide fibers; and metal fibers such as copper fibers, brass fibers, and steel fibers. Used. The reinforcing fiber is preferably contained in the entire composition in an amount of 0.5 to 16% by weight, more preferably 3 to 10% by weight. The length of the reinforcing fiber varies depending on the material. For example, the inorganic fiber preferably has a length of 15 to 50 mm, more preferably 20 to 45 mm. Organic fibers are preferably 0.8-4 mm,
1-2 mm is more preferred. The metal fiber is preferably 1 to 5 mm, more preferably 2 to 4 mm.

As a lubricant, graphite, antimony sulfide, molybdenum sulfide, etc., as a filler, cashew dust, rubber dust, barium sulfate, calcium carbonate, magnesium carbonate, silica, etc., as an abrasive, alumina powder, Zircon sand powder or the like is used alone or in combination of two or more. The lubricant is preferably contained in the entire composition at 2 to 8% by weight, more preferably at 3 to 6% by weight. The filler is preferably contained in the entire composition in an amount of 10 to 60% by weight, more preferably 20 to 50% by weight. The abrasive is preferably contained in the entire composition at 0.1 to 10% by weight, more preferably 0.5 to 8% by weight. Further, the metal powder optionally added is preferably contained in the entire composition in an amount of 1 to 8% by weight, more preferably 3 to 6% by weight. The usage ratio of each component constituting the friction material composition is adjusted so that the total amount thereof becomes 100% by weight.

The friction material composition according to the present invention is produced by mixing the respective components in an appropriate order. Further, the friction material according to the present invention is obtained by inserting and filling a backing metal and a friction material composition in a mold, molding by a heat-press molding method, and then performing a heat treatment. The heating temperature during molding is 130 to 17
0 ° C is preferred, and 140 to 160 ° C is more preferred. The pressure is preferably from 30 to 60 MPa, more preferably from 40 to 55 MPa. The heat treatment temperature is preferably 100 to 300 ° C.
50-250 degreeC is more preferable.

[0020]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto.

Examples 1 to 5 and Comparative Examples 1 and 2 The surface of a Ti-Ni alloy having a diameter of 3 mm and a length of 5 to 50 mm was cut in the same direction with a cutting machine to have a length of 4 mm and a width of 0.5.
An umbrella having a thickness of about 1.5 mm was produced, and then heated to 150 ° C. (shape memory treatment) to float the end of the umbrella to obtain a thermoelastic martensitic transformation shape memory alloy. After this,
At room temperature, the above-mentioned thermoelastic martensitic transformation shape memory alloy was deformed through a 3.2 mm cylindrical pipe so that the floating portion of the scab attached to the surface.

Next, a thermo-elastic martensitic transformation shape memory alloy obtained by deforming the floating portion of the sacrificer
The other materials in the amounts shown in Table 1 were blended and uniformly mixed by a mixer to obtain a friction material composition. Thereafter, the backing metal and the friction material composition are inserted and filled in the mold, and then heated at 150 ° C. and a pressure of 4 ° C.
Heat and pressure molding for 12 minutes under the condition of 0MPa, further 200
Heat treatment was performed at 5 ° C. for 5 hours to obtain a disc brake pad.

[0023]

[Table 1]

Next, a comparative test was performed on the disc brake pad according to the present invention and the disc brake pad of the comparative example. Table 2 shows the results. The test conditions are as follows.

Shear strength The strength at 22 ° C. and 300 ° C. was measured according to JASO C427. Abnormal noise generation status and effectiveness A 3000cc automatic vehicle (Nissan Motor Co., Ltd., model name Cedric (Y33)) was tested on the actual car of JASO C402, and the abnormal noise during the test was measured. The incidence and maximum sound pressure were determined. As for the effect, the effect as a disc brake during the test is expressed in μ value,
The amount of attack on the surface of the mating material was evaluated by the amount of grinding of the rotor. Formability The appearance of the disc brake pad was visually observed, and the occurrence of wrinkles and cracks was observed.

[0026]

[Table 2]

As shown in Table 2, it was confirmed that the disc brake pad according to the present invention was free of wrinkles and cracks and was excellent in all characteristics. On the other hand, the disc brake pad of Comparative Example 1 had a defect in shear strength, and the disc brake pad of Comparative Example 2 had defects in the actual vehicle abnormal noise generation rate and the actual vehicle abnormal noise maximum sound pressure.

[0028]

According to the first and second aspects of the present invention, there is provided a friction material composition capable of maintaining a reinforcing property and achieving a stable friction coefficient (μ ≧ 0.30) in response to weight reduction. Can be provided. The friction material according to the third aspect is suitable for weight reduction, can maintain a reinforcing property, and can obtain a stable friction coefficient (μ ≧ 0.30), and is industrially extremely suitable.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 101/00 C08L 101/00 F16D 69/02 F16D 69/02 D // B29L 31:16 B29L 31:16 F term (reference) 3J058 BA68 BA76 FA01 FA11 FA21 GA01 GA07 GA12 GA20 GA28 GA34 GA37 GA55 GA65 GA92 GA95 4F071 AA01 AB06 AF28 AF60 DA01 DA04 DA07 DA13 DA15 4F204 AA12 AA37 AA38 AA39 AB25 AD16 AH17 FA01 FB01 FB01 F11 FE06 CC071 CC181 CD001 DC006 FA040 FD010 FD147 FD170 GM03

Claims (3)

[Claims] 1. A friction material composition comprising 1 to 40% by weight of a shape memory alloy in all compositions. 2. The friction material composition according to claim 1, wherein the shape memory alloy is a thermoelastic martensitic transformation alloy that returns to a shape before deformation at a temperature of 100 ° C. or higher. 3. A friction material formed by heating and pressing the friction material composition according to claim 1.