JPH10330731A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material which does not suffer from fading while it retains the reduced juddering of a nonasbestine friction material, has a low coefficient of friction and improved abrasion loss by including a fibrous base material, a lubricant, an abrasive, a filler, a binder and a specified proportion of melamine cyanurate. SOLUTION: At least one fibrous base material selected among ceramic fibers, glass fibers, metallic fibers and aramid fibers is mixed with a solid lubricant such as antimony sulfide or molybdenum disulfide, an abrasive, a filler, a rubber-modified phenol resin prepared by modification with a phenolic resin, a melamine resin, an acrylic rubber, a silicone rubber or NBR, a binder such as COPNA resin and 3-20 vol.%, desirably 8-15 vol.% melamine cyanurate having a mean particle diameter of 100 μm or below. Thus, a friction material effective to suppress slip during braking and to heighten the coefficient of friction can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a friction material used for a disk brake of a vehicle such as an automobile or an industrial machine. In particular, the present invention relates to a friction material that can achieve a stable high coefficient of friction without a fade phenomenon.

[0002]

2. Description of the Related Art Conventionally, as a friction material used for a brake of an automobile or the like, an asbestos-based friction material containing asbestos as a main component has been used. However, its use has been banned due to environmental problems. Recently, disc pads using organic fibers such as Kevlar fiber (trade name of DuPont) have become mainstream because of their good squealing characteristics. .

[0003]

A friction material using such an organic fiber is exposed to a high temperature during braking, so that it is thermally degraded and a liquefied decomposition product is produced by using asbestos material or steel fiber. Phenomenon that increases in comparison with the used semi-meta material, liquefaction remains on the friction material surface, lowering the friction coefficient,
That is, there is a problem that a fade phenomenon occurs.

The present invention has been made to solve the above-described problems, and provides a friction material which is effective for suppressing slippage during braking and increasing the friction coefficient.

[0005]

Means for Solving the Problems Conventional friction materials using organic fibers are mixed with organic materials such as cashew dust in addition to organic fibers in order to stably improve abrasion resistance. Cashew dust is also exposed to high temperatures during braking,
Thermal decomposition produces liquefied material. When the amount of the liquefied matter increases, as described above, it causes a decrease in the friction coefficient, that is, a so-called fade phenomenon. The inventor has conducted intensive studies in order to solve the above-mentioned drawbacks of the conventional friction material using organic fibers, and as a result, the generation of a liquefied substance due to the thermal decomposition of such an organic component causes a fade phenomenon and a decrease in friction coefficient. I found that it was the cause.

Therefore, the inventor has proposed that the organic components of the friction material include:
By using a component that is more likely to be gasified than to be liquefied during thermal decomposition, it is possible to prevent a fade phenomenon during braking and to increase the friction coefficient, thereby completing the friction material of the present invention.

That is, the present invention relates to a friction material comprising a fiber base material, a lubricant, an abrasive, a filler, and a binder, wherein the friction material contains 3 to 20% by volume of melamine cyanurate. The friction material according to the present invention does not contain asbestos, and when exposed to a high temperature as a particulate material for controlling friction and wear with a fibrous material serving as a base material, does not liquefy, but uses a particulate material that is immediately vaporized. It is characterized by the following.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is preferable to use at least one of fibrous materials such as ceramic fiber, glass fiber, metal fiber, and aramid fiber as a fiber substrate.

[0009] As the ceramic fibers to be fibrous, S
iO ₂ , an oxide composed of Al ₂ O ₃ , potassium titanate,
Wollastonite or the like can be used.

[0010] Further, as the metal fibers to be fibrous, steel fibers, copper fibers, copper alloy fibers and the like can be used.

In the present invention, it is difficult to liquefy at high temperature,
Melamine cyanurate (manufactured by Nissan Chemical Industries, Ltd .: trade name MC-610 or the like) is an example of the powdery material that is easily vaporized. It is preferable to use fine particles having an average particle diameter of 100 μm or less. If the particle size exceeds 100 μm, it becomes difficult to mix the raw material powders uniformly, and there arises a problem that segregation occurs in the molded disk pad and the characteristics vary.

In the present invention, when the fine particles are used as a substitute for cashew dust, they are particularly effective. That is, the wear resistance, which is an advantage of the cashew dust, can be maintained.

In the present invention, the amount of the powdered melamine cyanurate to be added to the friction material is preferably in the range of 3 to 20% by volume. If it is less than 3% by volume, the coefficient of friction is not increased and the object cannot be achieved. If the content is more than 20% by volume, the organic component becomes large and the molded disk pad is easily deteriorated by heat, so that the life is shortened. More preferably, 8
~ 15% by volume.

In the present invention, mica, vermiculite, MgO, Z
An oxide ceramic such as rO ₂ can be used.

In the present invention, the wear resistance of the friction material is improved by adding a solid lubricating oil such as antimony sulfide and molybdenum disulfide.

In the present invention, the thermosetting resin serving as the binder is a phenol resin, a melamine resin, CO 2
PNA resin or acrylic rubber, silicone rubber, N
A rubber-modified phenol resin denatured by BR or the like can be used.

In the case of a disc brake, the disc is braked by friction between the disc and the rotor, and the disc surface is exposed to high temperatures. At this time, it can be easily inferred that if there is a liquid at the interface, the effect of the lubricating oil is exhibited and the friction coefficient is reduced. When a material which is easily vaporized without being liquefied when exposed to a high temperature is used as in the present invention, a high coefficient of friction and its stability can be maintained, exhibiting characteristics preferable as a disc pad.

Materials used for disc brakes that liquefy when exposed to high temperatures include binder resins such as phenolic resins, aramid fibers, and cashew dust, which are organic materials. And it is preferable to use the powdered granules of the present invention. Hereinafter, the present invention will be described specifically with reference to examples.

[0019]

EXAMPLE For the performance test of a friction material for a brake, an asbestos-free friction material was manufactured and a performance test was conducted.

In Table 1, the composition of the friction material according to the present invention is shown in Examples 1 to 3, and the composition of the friction material manufactured for comparison is shown in Comparative Examples 1 and 2.

[0021]

(Table 1) (Unit of volume:% by volume) Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Phenol resin 20 20 20 20 20 NBR powder 55 5 55 5 Copper fiber 7 7 7 7 7 Silicic acid Calcium fiber 7 7 7 7 7 Aramite fiber 10 10 10 10 10 Potassium titanate fiber 7 7 7 7 7 Graphite 5 5 5 5 5 Cashew paste (quantity) − − 5
10 13 (particle size, μm) (125) (125) (260) Melamine cyanurate (amount) 19 15 10 − − (particle size, μm) (30) (3) (100) sodium sulfate 20 20 20 20 20 Molybdenum disulfide-4 4 9 6 Fade phenomenon No No No Yes No evaluation point 4.5 5 4.5 4 4.5 Coefficient of friction (100 ° C) 4.12 4.21 4.07 3.67 3.85 (300 ° C) 4.05 4.11 3.98 3.27 3.56 Abrasion resistance (100 ° C) 0.07 0.09 0.08 0.11 0.12 (mm) (300 ° C) 0.45 0.57 0.34 0.54 0.67

For each friction material, the raw materials having the composition shown in Table 1 are mixed, thermoformed, and further post-cured to completely cure the phenol resin used as a binder to produce a disc brake pad for automobiles. did. The friction material was formed into a disc brake pad. Next, the manufacturing process will be briefly described.

First, raw materials were mixed according to the composition shown in Table 1. An Erich mixer was used for mixing.
The mixture is then sent to a mold and pressed into tablets. Place the tablet on the back metal coated with adhesive,
It was placed in another mold and heated and pressed to mold. Pressurization time is 1
The heating temperature is 150 ° C. for 0 minute, and the pressure is released in order to remove by-product gas. The pad molded in this way is 2
After post-curing at 00 ° C. for 10 hours, a disk pad was manufactured.

Through the above manufacturing process, the friction materials of Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention shown in Table 1 were produced. These pads were then tested for coefficient of friction with a dynamo tester and without brakes with a tester without. Table 1 shows the results.

In addition, the blank evaluation points, the coefficient of friction, and the wear resistance were evaluated as follows. Unevaluated evaluation point: An untested sound pressure was measured using an untested tester, and evaluated by a five-point method. 5 with few missing, 1 with many
And Friction coefficient, wear resistance: A brake test was conducted by installing a disc pad on a rotor and caliper made of cast iron (FC-25) using a 1/5 scale dynamo tester, and performing a brake test.
The torque and time applied to the wheel during braking were measured and calculated. The wear resistance was measured by measuring the thickness of the rotor and measuring the amount of wear.

In Examples 1 to 3 according to the present invention, melamine cyanurate was added to the friction material so that the friction material was 100 ° C higher than Comparative Examples 1 and 2 using cashew dust.
And the friction coefficient at 300 ° C. are high, and the performance as a friction material is high. Further, the abrasion resistance is equal to or less than that, and the material is excellent as a friction material without causing a fade phenomenon.

[0027]

The friction material according to the present invention improves the disadvantages of a low friction coefficient and a large amount of wear, while maintaining the good squealing characteristics of a non-asbestos friction material. It has no phenomenon and is suitable for a friction material such as a braking device in an automobile or an industrial machine.

Claims (1)

[Claims] 1. A friction material comprising a fiber base material, a lubricant, an abrasive, a filler, and a binder, wherein the friction material contains melamine cyanurate in an amount of 3 to 20% by volume.