JPH08326805A - Non-asbestos friction material - Google Patents

Abstract

PURPOSE: To provide a friction material which reduces the change of effectiveness at the times of low temperature and high temperature and also reduces noise generation at the time of low temperature. CONSTITUTION: A combination formation containing a thermosetting resin binding material (5-15wt.%), a non-asbestos fiber reinforcement material (10-40wt.%), a filler (40-75wt.%) and fluororesin fiber (specific gravity 1.7-2.2, water absorption ratio 0.03% or less, fiber diameter 5-30μm, fiber length 0.5-80mm; 0.2-30wt.%) is formed and made to be non-asbestos friction material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material made of a material containing fluororesin fibers. More specifically, the present invention relates to a friction material used for friction sliding materials (brake pads, brake linings, clutch facings, etc.) for industrial machines, railway vehicles, luggage vehicles, and automobiles.

[0002]

Friction materials for general brakes and clutches (brake pads, brake linings, clutch facings, etc.) are made of organic fiber, inorganic fiber (non-asbestos), metal fiber, etc .; Thermosetting resin binder: mainly composed of metal particles, metal oxide particles, a friction modifier such as resin dust, a filler such as barium sulfate, and the like.

However, when the conventional friction material is used when the temperature is low such as in winter or early morning, noise tends to occur due to an increase in friction coefficient at low temperature (cold noise). . In particular, as a result of absorbing moisture in the atmosphere at night, there is a phenomenon that the coefficient of friction becomes high when used the next morning, the effect of the brakes becomes abnormally high, and noise is noticeable (morning effect).
It was a problem. Measures against such an abnormal increase in braking effectiveness at low temperatures and noise generation at low temperatures are still insufficient.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a friction material in which the effect change between low temperature and high temperature is small and the generation of noise at low temperature is reduced.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above-mentioned problems, and as a result, by adding a fluororesin fiber as a filler of the friction material, the friction coefficient in the normal range is not lowered and the friction coefficient is lowered at a low temperature. The inventors have found that it is possible to suppress an increase in the friction coefficient, and have reached the present invention.

[0006] That is, the present invention is a non-asbestos-based friction material containing a thermosetting resin binder, a non-asbestos-based fiber reinforcing material, and a filler as a main component, which contains a fluororesin fiber. Regarding friction material.

Hereinafter, the present invention will be described in detail. The non-asbestos-based friction material referred to in the present invention refers to a material using non-asbestos-based fibers as a fiber reinforcing material, and mainly includes non-asbestos-based fiber reinforcing materials, thermosetting resin binders, and fillers containing fluororesin fibers. It is obtained by blending as a raw material and molding the blended composition into a desired shape according to a conventional method. The thermosetting resin binder of the present invention has a role of binding and hardening each compounding component of the friction material, and includes phenol resin (including straight phenol resin and various modified phenol resins such as rubber), melamine resin, Epoxy resin, cyanate ester resin and the like are used. Of these, phenol resin is preferably used. The amount of the thermosetting resin binder used is usually 5 to 15% by weight based on the total amount of the friction material. As the fiber reinforcing material which is the base material of the friction material, metal fibers such as steel fiber, copper fiber and brass fiber; aromatic polyamide fiber (aramid fiber etc .: commercially available products manufactured by DuPont, trade name Kevlar etc.), Organic fibers such as flame resistant acrylic fibers;
Examples include non-asbestos inorganic fibers such as potassium titanate fiber, glass fiber, alumina fiber, carbon fiber and rock wool. These can be used alone or in combination of two or more. The amount of the fiber reinforcing material used is usually 10 to 40% by weight based on the total amount of the friction material.

As the filler used in the present invention, friction dust such as resin dust (for example, cashew dust), rubber dust, etc .: alumina, silica, zirconia, etc. for the purpose of improving the coefficient of friction at low temperatures and improving wear resistance. Hard metal oxide particles, metal particles such as copper, brass, and iron: Vermiculite, mica and other scale-like inorganic substances for noise reduction: Solids such as graphite and molybdenum disulfide for the purpose of improving wear resistance and noise reduction Lubricant: Barium sulfate, calcium carbonate, etc. may be added for the purpose of improving mechanical properties such as compressive strength of the material.

The blending amount of the filler is preferably 40 to 75% by weight based on the total amount of the friction material. Among these, it is preferable to add 30 to 65% by weight of barium sulfate, calcium carbonate and the like, which are added for the purpose of improving mechanical properties. Further, it is preferable that the friction dust is mixed in an amount of 1 to 15% by weight, and the solid lubricant is added in an amount of 5 to 15% by weight.

As the metal oxide particles such as alumina, the metal particles such as copper, and the scale-like inorganic material such as vermiculite, at least one kind of them may be used, and the total content thereof is 1 of the total amount of the friction material. 10 to 10% by weight. The friction material of the present invention further contains a fluororesin fiber in addition to the filler. The fluororesin fibers used here are polytetrafluoroethylene resin (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), perfluoroalkoxy / fluororesin (PFA), ethylene / tetrafluoride. A fiber made of a fluororesin such as ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), or polyvinylidene fluoride (PVDF).
Further, preferably, the fiber length (average fiber length) 1 of the fluororesin fiber is 0.5 to 80 mm, and the fiber diameter (average fiber diameter).
d is 5 to 30 μm. The specific gravity of the fluororesin fiber is preferably 1.7 to 2.2, and the water absorption rate is preferably 0.03% or less.

The content of the fluororesin fiber is preferably 0.2 to 30% by weight, more preferably 0.5 to 15% by weight, based on the total amount of the friction material. If the blending amount is too small, the effect of the present invention that the increase in the friction coefficient in the low temperature region is suppressed cannot be exhibited, while if it is too large, the heat resistance decreases, which is not preferable.

The above blended composition is generally prepared in the form of tablets.
After preforming, the pressure plate sets it.
It is then placed in a hot press and thermoformed to a specified thickness and
Finished to a molded product of high density. Next, heat treat this molded product
Then, the friction material of the present invention is obtained by performing shape processing. this
In case of preforming, the surface pressure is 100-500 Kgf / cm²so
The thermoforming is performed at a temperature of 130 to 180 ° C. and a surface pressure of 200.
~ 1000Kgf / cm ²For about 3 to 15 minutes.
The heat treatment is performed at a temperature of 150 to 300 ° C for about 1 to 15 hours.
It is normal to go.

After that, if the friction material thus obtained is subjected to shape processing, a predetermined brake pad or the like can be obtained.

[0014]

The present invention will be described below with reference to examples. <Comparative Example 1, Examples 1 to 5> The types and amounts of the compounding ingredients shown in Table 1 were sufficiently stirred and mixed, and the obtained compounded composition was preformed into a tablet at a surface pressure of 200 Kgf / cm ^2. , This preform was transferred to a hot press where a pressure plate was set, and the temperature was 155 ° C and the surface pressure was 500 Kg.
Thermoforming was performed at f / cm ² for 10 minutes. Next, this molded product was heat-treated at 200 ° C. for 10 hours, and further subjected to shape processing such as polishing to prepare a brake pad.

[0015]

[Table 1]

Next, each brake pad described above was attached to a full size dynamometer and an evaluation test was conducted. The size of the test piece at this time is as follows.・ Thickness of pressure plate: 5 mm ・ Thickness of friction material test piece: 10 mm ・ Area of friction surface: 45 cm ² Speed of full size dynamometer was 20 km / h, temperature was 80 ° C and 10 ° C, and at each temperature The friction coefficient was measured when the brake fluid pressure was 5, 10 and 15 Kgf / cm ² . Also, the squeal occurrence level at 10 ° C is 1 to 5
The evaluation was carried out on a scale of 5 (1 to 2 are desirable levels). still,
The squeal was measured at the sound pressure level.

The results are shown in Table 2.

[0018]

[Table 2]

[0019]

According to the present invention, by incorporating a fluororesin fiber into a conventional friction material, it is possible to suppress an increase in the friction coefficient in a low temperature range without lowering the effect in a normal use range. Therefore, it is possible to reduce a change in braking effectiveness between low temperature and high temperature, and to reduce noise generation at low temperature.

Claims (6)

[Claims] 1. A non-asbestos-based friction material comprising a thermosetting resin binder, a non-asbestos-based fiber reinforcing material, and a filler as a main component, which contains a fluororesin fiber. 2. The non-asbestos-based friction material according to claim 1, wherein the content of the fluororesin fiber is 0.2 to 30% by weight of the total amount of the friction material. 3. The non-asbestos-based friction material according to claim 1, wherein the content of the fluororesin fiber is 0.5 to 15% by weight based on the total weight of the friction material. 4. The specific gravity of the fluororesin fiber is 1.7 to 2.2,
The non-asbestos friction material according to claim 1, which has a water absorption rate of 0.03% or less. 5. A fluororesin fiber having a fiber diameter of 5 to 30 μm and a fiber length of 0.5 to 80 mm.
Non-asbestos friction material described. 6. A thermosetting resin binder 5 to 15% by weight, a non-asbestos fiber reinforcing material 10 to 40% by weight, a filler 40 to 75% by weight, and a fluororesin fiber 0.2 to 30% by weight. Non-asbestos friction material made by.