JPH108033A - Non-asbestos-based friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject friction material for brake, etc., capable of preventing lowering of effect after heat history and effect at low temperature even when addition amount of rigid particles is reduced by using sepiolite fiber in at least a part of a fiber substrate. SOLUTION: This friction material for brake consists essentially of (A) a non-asbestos-based fiber substrate, (B) a thermosetting resin and (C) a filler. The component A is a combination of products of plural non asbestos-based fibers. The friction material comprises sepiolite fiber, preferably in an amount of 1-40wt.% based on total amount of the friction material as a part of the component A and has <=3wt.% hard particle content having >=5Moh's hardness. Furthermore, the friction material comprises preferably 5-50wt.% component A, 5-18wt.% component B and 30-80wt.% component C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to non-asbestos-based friction used for friction sliding materials (disc brake pads, drum brake linings, clutch facings, brake shoes, etc.) for industrial machines, railway vehicles, luggage vehicles, and automobiles. About materials.

[0002]

2. Description of the Related Art Friction materials for general brakes and clutches (disc brake pads, drum brake linings, clutch facings, brake shoes, etc.) are made of organic fibers,
The main materials are fiber base materials such as inorganic fibers (non-asbestos) and metal fibers, thermosetting resin binders such as phenolic resins, and fillers such as friction modifiers such as resin dust and solid lubricants such as graphite. It is configured as a component.

[0003] Conventional friction materials have been problematic in that their effectiveness after heat history or at low temperatures may decrease due to the temperature characteristics of fillers and additives. That is, if the ratio of organic fibers (aramid fibers, etc.), resin dust, rubber, etc. is high,
After braking at a high temperature, the shear strength and the effectiveness of the material tend to decrease, and the effect at a low temperature (50 ° C. or lower) tends to decrease.

In order to overcome this problem, a method has been attempted in which hard particles such as alumina and chromium oxide are added or increased as an abrasive, or a friction coefficient is improved by relatively reducing solid lubricant such as graphite. However, when a large amount of abrasive is used, there is a disadvantage that a noise generation rate is increased (noise property is deteriorated).

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a friction material in which the effect after heat history or the effect at low temperature is prevented from lowering without deteriorating or suppressing the noise. As an issue.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems, and as a result, by using sepiolite fibers for at least a part of the fiber base material, even if the addition amount of the hard particles is reduced, the heat content is reduced. The present inventors have found that it is possible to prevent a reduction in the efficacy after the history and the efficacy at a low temperature, and arrived at the present invention.

That is, the present invention provides a non-asbestos fiber base material,
Thermosetting resin binder, and a friction material containing filler as a main component, wherein the fibrous base material is a combination of a plurality of non-asbestos fibers, and contains sepiolite fibers as a part of the fibrous base material. And a content of hard particles having a Mohs' hardness of 5 or more is 3% by weight or less.

The present invention also provides the above non-asbestos-based friction material in which the content of sepiolite fibers is 1 to 40% by weight based on the total amount of the friction material. The present invention also provides the above-mentioned non-asbestos-based friction material, which is substantially free of hard particles having a Mohs hardness of 5 or more.

Further, the present invention provides the above non-asbestos-based friction material in which the content of the thermosetting resin binder is 18% by weight or less based on the total amount of the friction material. Also, the present invention
The present invention provides the non-asbestos-based friction material comprising 5 to 50% by weight of a non-asbestos fiber base material, 5 to 18% by weight of a thermosetting resin binder, and 30 to 80% by weight of a filler.

In the friction material of the present invention, by using sepiolite fiber as the fiber base material, the effect after heat history and the effect at low temperature are improved, and the reduction in noise is significantly suppressed.

[0011]

Embodiments of the present invention will be described below. The friction material of the present invention is a non-asbestos-based friction material using a non-asbestos-based fiber as a fiber base material, which mainly comprises the non-asbestos-based fiber base material, a thermosetting resin binder, and a filler. It is.

The present invention is characterized in that sepiolite fibers are contained as at least a part of the fiber base material. Sepiolite is a natural fibrous clay mineral, the main component of which is hydrous magnesium silicate.In addition, it contains calcium oxide, magnesium oxide, aluminum oxide, silicon dioxide, iron oxide, etc. I have. The cross section of a single fiber of sepiolite has a crystal structure in which talc is alternately stacked, and has a large number of pores in the fiber, so that the adsorption effect is high. Further, it has thixotropy, exhibits a thickening effect when vigorously stirred in water or a resin, and has a low viscosity when the shearing force is large, and has a high viscosity when the shearing force is small. Further, when sepiolite is granulated with water and dried, consolidated particles are obtained. When heated, the particles are gradually dehydrated and turned into ceramics, and exhibit plasticity like kaolin. The sepiolite fiber used in the present invention has an average fiber length of 30 to
Those having a diameter of 50 μm and an average fiber diameter of 0.1 to 0.4 μm are preferred.

Examples of the fiber base material include metal fibers such as steel fibers, copper fibers, and brass fibers in addition to the above-mentioned sepiolite fibers; aromatic polyamide fibers (aramid fibers and the like: commercially available products manufactured by DuPont, Kevlar under the trade name). And non-asbestos inorganic fibers such as potassium titanate fiber, glass fiber, alumina fiber, carbon fiber and rock wool. One or two or more of these can be used in combination. Of these, organic fibers such as aramid fibers or fibrillated aramid fibers (aramid pulp) and / or inorganic fibers such as glass fibers are preferably used in combination.

The content of the sepiolite fiber is preferably 1 to 40% by weight, more preferably 2 to 40% by weight based on the total amount of the friction material.
30% by weight. If the amount is within this range, the effect of preventing the decrease in efficacy after heat history and the decrease in efficacy at low temperature will not be insufficient because the amount is too small. In addition, the generation of noise is not increased due to too much, and the wettability with the binder is not reduced, and the strength is not varied, and the quality is not unstable.

The amount of the entire fiber substrate is usually 5 to 50% by weight, preferably 10 to 45% by weight, based on the total amount of the friction material.
It is. The ratio of sepiolite fibers in the total amount of the fiber base material is not particularly limited, but is preferably about 10 to 70% by weight.

The thermosetting resin binder of the present invention has a role of binding the respective components of the friction material, and a phenol resin, a melamine resin, an epoxy resin, a cyanate ester resin or the like is used. Of these, a phenol resin is preferably used. The amount of the thermosetting resin binder used is not particularly limited, but is preferably 1 to the total amount of the friction material.
Not more than 8% by weight. If it exceeds 18% by weight, the effect is lowered (fading becomes large), which is not preferable. More preferably, it is 5 to 18% by weight based on the total amount of the friction material.

The filler used in the present invention includes organic fillers such as resin dust (for example, cashew dust); hard particles of metal oxides such as alumina, silica, and zirconia; and metal particles such as copper, brass, and iron. Metallic filler such as;
Inorganic fillers such as flaky inorganic substances such as vermiculite and mica, and inorganic compounds such as barium sulfate and calcium carbonate; solid lubricants such as graphite and molybdenum disulfide; The amount of the filler is preferably 30 to 80% by weight, more preferably 40 to 7% by weight based on the total amount of the friction material.
0% by weight.

In the present invention, the content of hard particles having a Mohs hardness of 5 or more is set to 3% by weight or less. If the content of such hard particles exceeds 3% by weight, the noise properties deteriorate. On the other hand, in the present invention using sepiolite fiber as the base fiber, even if the hard particles are as small as 3% by weight or less, the effect after heat history and the effect at low temperature do not decrease.
In particular, it is preferable that hard particles having a Mohs hardness of 5 or more, which is harder than the friction mating member (a brake disk, a brake drum, or the like), are not substantially contained in the friction material.
Here, examples of the hard particles having a Mohs hardness of 5 or more include metal oxides such as alumina, silica, zirconia, and chromium oxide.

The friction material of the present invention comprises the above-described fiber base material,
After preliminarily forming the blended composition obtained by uniformly stirring and mixing the thermosetting resin binder and the filler into a tablet or the like, this is placed in a mold or the like, and is pressurized and heated, and is subjected to a predetermined heat treatment. Obtain molded articles of thickness and density. Next, this molded product is heat-treated and further subjected to finishing such as shape processing to obtain the friction material of the present invention. Various conditions in these steps are appropriately selected in accordance with a conventional method.
Carried out at 00~500kgf / cm ² or so, the pressing and heating the molding at a temperature 130 to 180 ° C. and a surface pressure 200~1000k
gf / cm ² , and heat treatment at a temperature of 150-3.
Generally, it is performed at about 00 ° C.

[0020]

Embodiments of the present invention will be described below.

[0021]

Examples 1-4, Comparative Examples 1-2 The types and amounts of the ingredients shown in Table 1 were sufficiently stirred and mixed, and the resulting composition was preliminarily prepared in a mold at a surface pressure of 200 kgf / cm ² . Molded,
Next, the temperature is 150 ° C and the surface pressure is 200kgf / cm in the mold.
Pressure and heat molding at ²
Heat treatment was performed at 200 ° C., and shape processing such as polishing was performed to prepare a friction material test piece. The size of the obtained test piece was 22
It is 0 mm × 190 mm × 16 mm.

Next, the obtained test piece was attached to an actual vehicle, and the following evaluation tests were performed.

(1) Efficacy test 1 at braking initial speed (V) = 65 km / h and deceleration 0.3 G
After rubbing 00 times, V = 50 km / h, deceleration 0.
In 3G, the input (brake fluid pressure P: kgf / c
m ² ) and the output (brake torque T: kgf · m) (T / P).

In the above-mentioned efficacy test, the initial braking speed (V)
= 60 km / h and a deceleration of 0.3 G were performed, and the friction material temperature was increased to a maximum of 300 to 350 ° C., and then cooled, and the effect (T / P) after the heat history was measured.
Further, the T / P at 50 ° C. was measured to determine the effect at a low temperature. Further, the T / P at 90 ° C. was measured and defined as the effect at normal temperature. The larger the T / P value, the higher the braking effect.

(2) Evaluation of noise characteristics A friction material test piece was attached to an actual vehicle, and the initial braking speed (V) =
The presence / absence of noise when braking was performed under the conditions of 30 to 50 km / h and deceleration of 0.1 to 0.3 G was examined, and the noise generation rate was obtained by performing the braking plural times.

Table 1 also shows the results of the evaluation test.

[0027]

[Table 1]

As can be seen from the results of this evaluation test, in the friction material using the sepiolite fiber of the present invention as a fiber base material, the effect after heat history and the low-temperature effect hardly decrease compared to the normal effect. On the other hand, in the comparative example using no sepiolite fiber, the effect after heat history and the effect at low temperature are reduced. In the friction material of the present invention,
The noise generation rate was lower than that of Comparative Example 1 in which conventional hard particles were used as the abrasive, indicating that the noise characteristics were significantly improved.

[0029]

According to the friction material of the present invention, it is possible to prevent a reduction in effectiveness after heat history and a reduction in effectiveness at low temperatures without reducing noise.

Claims (5)

[Claims] 1. A friction material mainly comprising a non-asbestos fiber base material, a thermosetting resin binder, and a filler, wherein the fiber base material is a combination of a plurality of non-asbestos fibers. A non-asbestos-based friction material characterized by containing sepiolite fibers as a part of the fiber base material and containing 3% by weight or less of hard particles having a Mohs hardness of 5 or more. 2. The non-asbestos-based friction material according to claim 1, wherein the content of sepiolite fibers is 1 to 40% by weight based on the total amount of the friction material. 3. The non-asbestos-based friction material according to claim 1, wherein the non-asbestos-based friction material is substantially free of hard particles having a Mohs hardness of 5 or more. 4. The non-asbestos-based friction material according to claim 1, wherein the content of the thermosetting resin binder is 18% by weight or less based on the total amount of the friction material. 5. A non-asbestos fiber base material of 5 to 50% by weight, a thermosetting resin binder of 5 to 18% by weight, and a filler of 30 to 80%.
The non-asbestos-based friction material according to claim 1, which comprises about 100% by weight.