JPH10158631A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high amt. of magnesium hydroxide to be incorporated into a friction material and to obtain a friction material having good high-temp. friction characteristics by compounding a thermosetting resin with a nonfibrous magnesium hydroxide powder surface-treated so as to improve the affinity for a thermosetting resin. SOLUTION: Examples of a thermosetting resin usable as the binder for a friction material are phenolic resins, urea resins, melamine resins, and their modifications, phenol resins being esp. pref. A magnesium hydroxide powder having an aspect ratio of 3 or lower and a particle size of 0.1-1.0μm is pref. The surface of the powder is treated with a surface treating agent such as a stearate or a coupling agent such as a silane coupling agent. The compounding ratio of magnesium hydroxide is 50-75vol.%. The material is further mixed with 5-8vol.% antimony trioxide and/or antimony trisufide as the friction modifier and if necessary a fibrous reinforcement, a filler, etc., and then is thermally press molded and thermally treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material, and more particularly to a friction material used for a disk pad or a brake lining of an automobile or various industrial machines.

[0002]

2. Description of the Related Art In recent years, non-asbestos-based friction materials which do not contain asbestos have been developed as friction materials used for disk pads and brake linings of automobiles and various industrial machines, and many proposals have been made. .

For example, Japanese Patent Application Laid-Open No. 6-228327 discloses a friction material containing a reinforcing fiber other than asbestos, a thermosetting resin such as a phenol resin, and a filler such as graphite and barium sulfate. There has been proposed a friction material in which magnesium hydroxide fibers are contained in an amount of 50% by volume or less based on the total amount of the friction material, thereby increasing the strength after heat history and preventing the occurrence of cracks.

[0004] This kind of friction material generally has a temperature
It is used in a temperature range up to a high temperature of 00 ° C. or higher. However, when the operating temperature is 250 ° C. or higher, a thermosetting resin such as a phenol resin constituting the friction material is thermally decomposed and lowers the friction characteristics of the friction material. .

On the other hand, magnesium hydroxide is 36
When magnesium hydroxide is added to the friction material because it undergoes endothermic decomposition at around 0 ° C, it absorbs part of the heat generated by the brakes, etc., lowering the temperature of the sliding surface, and the frictional characteristics due to the thermal decomposition of the thermosetting resin Can be prevented from decreasing.

[0006] The friction material is generally produced by molding and curing at 130 to 250 ° C. However, magnesium hydroxide is not decomposed at this temperature, and the endothermic effect at 350 ° C or higher at which the thermosetting resin is rapidly thermally decomposed. Demonstrate. Aluminum hydroxide other than magnesium hydroxide exhibits such an endothermic effect. However, aluminum hydroxide is decomposed at the time of molding because its decomposition temperature is about 200 ° C.
The effect of preventing thermal decomposition of the thermosetting resin at 350 ° C. or higher cannot be obtained.

[0007]

As described above, magnesium hydroxide has an effect of preventing thermal decomposition of a thermosetting resin of a friction material and stabilizing friction characteristics when the friction material is used at a high temperature. The effect increases as the amount of magnesium hydroxide increases. In particular, excellent effects can be obtained by adding 50% by volume or more of magnesium hydroxide to the total amount of the friction material.

However, since magnesium hydroxide used in the friction material described in JP-A-6-228327 is in the form of a fiber, if it is added in an amount of 50% by volume or more with respect to the total amount of the friction material, the raw material for molding is extremely low. Become bulky. When such a molding material is molded, cracks are likely to occur during molding due to a large springback of the molded body during molding.

For these reasons, Japanese Patent Application Laid-Open No. 6-2283 is disclosed.
In the friction material described in Japanese Patent No. 27, magnesium hydroxide fibers cannot be blended in a large amount, and therefore, there has been a drawback that the effect of stabilizing the friction characteristics by magnesium hydroxide cannot be sufficiently obtained.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a friction material which can contain a large amount of magnesium hydroxide and has good friction characteristics at high temperatures.

[0011]

SUMMARY OF THE INVENTION A friction material according to the present invention comprises a thermosetting resin containing 5 to 75% by volume of a non-fibrous magnesium hydroxide powder which has been subjected to a surface treatment for enhancing affinity with the thermosetting resin. It is characterized by comprising.

In the friction material of the present invention, since non-fibrous magnesium hydroxide powder is blended as magnesium hydroxide, as in the case of using magnesium hydroxide fiber,
The molding raw material does not become excessively bulky. Therefore, even when magnesium hydroxide is blended in a large amount with respect to the total amount of the friction material, a good friction material can be produced without cracking during molding. In addition, the magnesium hydroxide powder has been subjected to a surface treatment that enhances the affinity with the thermosetting resin, so it is well compatible with the thermosetting resin. It does not occur.

Accordingly, a large amount of magnesium hydroxide, which is effective for stabilizing the friction characteristics at a high temperature, can be blended to provide a friction material having good friction characteristics at a high temperature.

In the present invention, in particular, antimony trioxide and / or antimony trisulfide is used as a friction modifier in an amount of 10%.
By containing the content by volume% or less, the friction characteristics can be further stabilized, and the wear of the friction material can be reduced.

[0015]

Embodiments of the present invention will be described below.

The thermosetting resin serving as a binder for the friction material of the present invention includes a phenol resin, a urea resin, a melamine resin and modified resins thereof, and a phenol resin is particularly preferable.

The non-fibrous magnesium hydroxide powder used in the present invention has an aspect ratio of 3 or less and a particle size of 0.1 to 1.0.
A powder of about μm is preferred.

In the present invention, such a magnesium hydroxide powder is subjected to a surface treatment for enhancing the affinity with a thermosetting resin, for example, a treatment with a surface treating agent such as a stearate, a silane coupler or the like. And then blended with the thermosetting resin. In the case of treating with a surface treating agent, the surface treating agent is attached to the magnesium hydroxide powder in an amount of about 1 to 10% by weight. When treating with a coupling agent, the coupling agent is added to the magnesium hydroxide powder in an amount of 0.1%.
About 5% by weight. By performing such a surface treatment, mixing and uniform dispersibility of the magnesium hydroxide powder and a thermosetting resin such as a phenol resin are improved, and cracks or the like during production or use can be prevented.

In the present invention, the non-fibrous magnesium hydroxide powder subjected to such a surface treatment is blended in an amount of 5 to 75% by volume. As described above, the higher the blending amount, the more stable the friction characteristics at high temperatures. However, if the blending amount exceeds 75% by volume, the amount of the thermosetting resin relatively decreases, the bonding strength decreases, and cracks occur during molding. Is more likely to occur. The preferred amount of the magnesium hydroxide powder is 50 to 75% by volume.

The friction material of the present invention further contains antimony trioxide and / or antimony trisulfide as a friction adjusting material to further stabilize the friction characteristics at a high temperature and enhance the abrasion resistance. The wear of the material can be prevented. If the content of antimony trioxide and / or antimony trisulfide is excessively large, the compounding amount of other materials is relatively reduced and the properties as a friction material are impaired.
The content of antimony trioxide and / or antimony trisulfide is preferably 10% by volume or less, more preferably 5 to 8% by volume of the friction material.

The friction material of the present invention comprises, as other components,
One kind of reinforcing fibers other than asbestos, for example, organic fibers such as aramid fibers, glass fibers, rock wool, ceramic fibers, inorganic fibers such as potassium titanate fibers, and metal fibers such as iron, copper, bronze, aluminum, and brass. Or two or more kinds; fillers, for example, one or more kinds of ceramic powders such as graphite, barium sulfate, molybdenum disulfide, cashew dust, metal powder, alumina, calcium carbonate, zirconium silicate, etc. May be.

The preferred compounding ratio of the friction material of the present invention is as follows. Thermosetting resin: 8 to 20% by volume Non-fibrous magnesium hydroxide powder: 50 to 75% by volume Reinforcing fiber: 2 to 25% by volume Filler: 8 to 30% by volume Friction modifier (antimony trioxide and / or Antimony trisulfide): 3 to 10% by volume The reinforcing fibers preferably have a fiber diameter of 3 to 300 μm and a fiber length of 0.1 to 5 mm. Further, a filler having a particle size of about 0.5 to 500 μm is suitable.

The friction material of the present invention is obtained by mixing a thermosetting resin, a non-fibrous magnesium hydroxide powder, other reinforcing fibers, a filler, a friction modifier and the like at a predetermined ratio, and mixing the mixed material with the thermosetting resin. Curing temperature, for example, 130 to 180 ° C., 50 if a phenol resin is used as the thermosetting resin.
It can be manufactured by heat-press molding at ６００600 kg / cm ² for 3 to 15 minutes, followed by heat treatment at 150 to 200 ° C. for 3 to 15 hours.

[0024]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist.

The specifications of the materials used in the following Examples and Comparative Examples are as follows.

Non-fibrous magnesium hydroxide powder (surface-treated product): Magnesium hydroxide powder having an aspect ratio of 1 to 3 and an average particle diameter of 1 μm was added to sodium stearate at 5% by weight.
Surface treated with. Non-fibrous magnesium hydroxide powder (non-surface-treated product): a powder having the same aspect ratio and average particle size as the above-mentioned surface-treated product but not subjected to surface treatment. Magnesium hydroxide fiber: Magnesium hydroxide fiber having a fiber diameter of 0.1 to 5 μm and a fiber length of 10 to 50 μm. Thermosetting resin: phenolic resin Copper fiber: average fiber diameter 60 μm, average fiber length 3 mm.

Aramid fiber: Fibrillar graphite having an average fiber diameter of 12 μm and an average fiber length of 6 mm: Average particle diameter of 150 μm Alumina: Average particle diameter of 5 μm Cashew dust: Average particle diameter of 150 μm Antimony trisulfide: Average particle diameter of 50 μm Antimony trioxide: Average particle size 1 μm Examples 1 to 8 and Comparative Examples 1 to 4 Materials were uniformly dispersed by a dry mixer with the composition shown in Table 1,
Mix and mix the material at a temperature of 150 ° C and a pressure of 400 kg / c
After heating pressure forming for 10 minutes m ^2, and the heat-treated at a temperature 210 ° C. in a hot-air dryer for 10 hours, the length 150 mm, width 5
A friction material having a thickness of 0 mm and a thickness of 15 μm was manufactured.

The obtained friction material was subjected to a friction test using a dynamo tester under the following conditions. Initial braking speed: 100 km / hr Final speed: 50 km / hr Braking deceleration: 0.4 G Brake temperature before braking: 350 ° C. Table 1 shows the presence or absence of cracks during molding and heat treatment, and the friction test results. From Table 1, the friction material of the present invention has no problem of crack generation even if a large amount of magnesium hydroxide is blended.
It can be seen that the friction characteristics at high temperatures are good.

[0029]

[Table 1]

[0030]

As described above in detail, according to the friction material of the present invention, a friction material having extremely good friction characteristics at high temperatures is provided.

Claims (2)

[Claims] 1. A non-fibrous magnesium hydroxide powder which has been subjected to a surface treatment for enhancing the affinity with a thermosetting resin is provided in an amount of 5 to 75%.
A friction material comprising a thermosetting resin containing about 30% by volume. 2. The thermosetting resin according to claim 1, wherein the thermosetting resin contains 10% by volume of antimony trioxide and / or antimony trisulfide.
A friction material comprising: