JPH08291223A - Friction material - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent excessive wear of the friction material and the mating material under severe operating conditions. A friction material comprising a fibrous base material, a resin binder, and a filler such as a solid lubricant. The fibrous base material contains iron-containing potassium titanate fibers or whiskers and has a solid lubrication property. As an agent, 0.7 for the whole friction material
~ 2.5 vol% antimony trisulfide. Since the compounding ratio of antimony trisulfide is relatively small, it is possible to suppress excessive wear of the mating material under severe usage conditions (such as repeated braking at a speed close to 200 km / h), and heat resistance. By using potassium titanate fibers or whiskers containing a particularly high iron content, excessive wear of the friction material itself can be suppressed to a good level. It is preferable that the abrasive has a small particle size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material used as a disc brake pad, a drum brake lining, a clutch facing or the like of an automobile or the like.

[0002]

2. Description of the Related Art Friction materials used as disc brake pads, drum brake shoes, etc. of automobiles play an important role in converting kinetic energy into heat energy by frictionally engaging with the disc rotor and brake drum which are the mating members. I carry it. Therefore, the friction material has not only a sufficient coefficient of friction, but also heat is constantly generated at the time of braking and has a high temperature. Therefore, it is necessary that the friction material has high strength against such heat and wear resistance. Further, the friction coefficient is required to be stable with little change due to the temperature change due to the heat. Furthermore, it is important that the aggression against the mating material is small and that the noise (brake squeal) and the occurrence of judder are small. Therefore, the characteristics required for the friction material cover many items.

Therefore, in order to satisfy these various characteristics, the friction material has conventionally been constructed as a composite material composed of many materials. That is, the friction material is a fiber base material that is a component made of a fibrous material and forms a skeleton, and a resin binder made of a resin component that bonds and holds the fiber base material,
It is a component made of a powdery material and is formed from various fillers which are dispersed and filled in a matrix of these fibers and a binder. And, as the filler component, mainly barium sulfate for improving wear resistance and heat resistance, constitutional fillers such as calcium carbonate, friction modifiers such as cashew dust, abrasive agents for improving the friction coefficient,
In addition to these, solid lubricants are generally used.

This solid lubricant is used to ensure the thermal stability of the friction coefficient by its lubricity and to improve the wear resistance of the friction material. As such a solid lubricant, various types of graphite (graphite) such as natural scaly graphite have been most commonly used. However, since this graphite alone does not have sufficient lubricity especially under high load (at high temperature), it has been conventionally used to use antimony trisulfide Sb ₂ S ₃ which is a metal sulfide together with this graphite as a solid lubricant. Is generally known. In addition, this antimony trisulfide forms a hard film on the surface of the friction material by heat under high load (at high temperature), thereby protecting the friction material and improving its wear resistance. It is blended in a proportion of at least 3% by volume, usually 5% by volume or more based on the whole.

A friction material using antimony trisulfide as described above is disclosed in, for example, Japanese Patent Laid-Open No. 1-29503.
There is one disclosed in Japanese Patent No. Here, in order to prevent vapor lock and fade mainly, a specific heat-resistant resin binder is used, and antimony trisulfide is mixed in a proportion of 5 to 20% by weight of the whole friction material. Further, in the friction material disclosed in JP-A-6-129455, 5 to 10% by volume of antimony trisulfide is mixed with iron sulfide.

A fiber base material made of a fibrous material is
It forms the skeleton of the friction material, imparts appropriate porosity to it, and imparts strength and elasticity to the entire friction material, and is an important component as a base material of the friction material. Asbestos fibers (asbestos) have been used as such a fiber substrate in the past, but in recent years, various other fiber materials have been used in place of the asbestos fibers. One example is steel (carbon steel) fibers. However, the friction material (semi-metallic friction material) using this steel fiber as the main material of the fiber base material has advantages such as excellent heat resistance and wear resistance, and a relatively high friction coefficient. However, on the other hand, it has a drawback that it is heavy, rusts, and damages a counterpart material made of the same kind of steel and is easily worn.

Therefore, in recent years, so-called non-steel type friction materials or low steel type friction materials, in which steel fibers are not used as the fiber base material or the compounding amount thereof is small even when used, have become the mainstream of friction materials. There is. In this non-steel (and low steel) friction material, as the fiber base material, various organic fibers such as aramid fibers, glass fibers, various inorganic fibers such as potassium titanate fibers or whiskers, copper fibers, Non-ferrous metal fibers such as brass fibers are used. The most representative of these are aramid fibers, which have particularly high heat resistance among the light weight organic fibers, and potassium titanate fibers or whiskers, which have excellent abrasion resistance despite having a low attacking property of the mating material.

[0008] Further, these fiber materials are generally used in combination of a plurality of kinds because only one kind of them cannot obtain sufficient performance as a substitute for asbestos fiber. Further, in order to increase the friction coefficient of the friction material, it is common to use abrasive inorganic hard inorganic fibers together with these non-steel fiber base materials. The abrasive hard inorganic fiber generally has a Mohs hardness of 4 or more (provided that the Mohs hardness is higher than potassium titanate fibers or whiskers having a Mohs hardness of 4), specifically, slag wool, rock. Wool or ceramic fiber is used.

Regarding the potassium titanate fiber or whisker used as the fiber base material of the friction material, Japanese Patent Application Laid-Open No. 3-237184 filed by the applicant of the present application discloses the use of an iron-containing material. Has been done. That is, this potassium titanate fiber or whisker contains iron as an impurity in an amount of about 0.1 to 2.0% by weight in terms of metal, and compared with pure potassium titanate fiber or whisker containing no iron. Particularly high heat resistance. Therefore, by using this as at least a part of the fiber base material, it is possible to improve the wear resistance especially at a high temperature.

[0010]

[Problems to be Solved by the Invention] By the way, recently, general passenger cars are also becoming faster and higher in output, and the braking conditions tend to become more severe accordingly. And, for example, in the case of running an autobahn in Europe, the number of cases in which braking is repeated at a speed of 200 km / h or a speed close to 200 km / h is increasing. In recent years, racing of passenger cars has become popular, and even in such a case, severe braking is repeatedly performed. Therefore, it has become necessary to consider the use of friction materials such as disc brake pads under such severe conditions.

When the friction material is used under such severe conditions, the first problem is its excessive wear. That is, the wear of the friction material is cumulatively increased by the high heat generated under the severe braking condition, and the wear amount is excessively increased as compared with the normal time. This tendency is particularly remarkable in the case of a non-steel friction material containing organic fibers such as aramid fibers, which have relatively high heat resistance but are relatively weak against high heat. Therefore, in the case of a friction material used under such severe conditions, as described above, a relatively large amount of antimony trisulfide Sb ₂ S ₃ as a solid lubricant is blended to suppress excessive wear. It is possible to do it.

However, when a friction material containing a relatively large amount of antimony trisulfide is actually manufactured and tested, excessive wear of the friction material under severe operating conditions can be suppressed. It was found that a new defect would occur with it. That is, the wear of the mating material such as the brake disc excessively increases. Then, such excessive wear of the mating material is not only unfavorable, but also causes noise and judder.

[0013] Therefore, an object of the present invention is to provide a friction material capable of suppressing excessive wear of the friction material itself and the counterpart material when used under severe conditions.

[0014]

DISCLOSURE OF THE INVENTION As a result of examining the excessive wear of the above-mentioned mating material which occurs under severe usage conditions, the present inventors found that the cause is antimony trisulfide Sb ₂ S ₃ , and therefore It was found that excessive wear of the mating material can be suppressed by reducing the compounding ratio of. But,
As a result, the wear of the friction material itself increases. Therefore, the inventors of the present invention conducted further tests and studies focusing on the above-mentioned iron titanate-containing potassium titanate fiber or whisker, and as a result, the antimony trisulfide content was set to a relatively small predetermined ratio and the fiber was added. It was found and confirmed that by using the potassium titanate fiber or whiskers as at least a part of the base material, it is possible to suppress both excessive wear of the friction material and the counterpart material under severe use conditions. .

That is, the friction material according to the present invention is a friction material containing a fiber base material, a resin binder, and a filler such as a solid lubricant, and the titanic acid containing iron is used as the fiber base material. In addition to containing potassium fibers or whiskers, the solid lubricant contains 0.7 to 2.5% by volume of antimony trisulfide based on the whole friction material.

[0016]

The antimony trisulfide Sb ₂ S ₃ chemically changes due to the high heat generated at the time of high load to form a hard film on the surface of the friction material to protect the friction material and improve its wear resistance. Therefore, by compounding this, it is possible to suppress and prevent an excessive increase in wear of the friction material when used under severe conditions. However, in this case, if the blending ratio of antimony trisulfide is high, the wear amount of the mating material increases excessively. It is considered that this is because the film formed of antimony trisulfide is so hard that it acts as an abrasive and attacks the mating material to grind it. Moreover, since the aggressiveness of this mating material is raised exponentially by the high heat under severe usage conditions, as in the case of excessive wear of the friction material, it is assumed that the mating material will become excessively worn. Conceivable.

In the friction material according to the present invention, the mixing ratio of this antimony trisulfide is relatively small, and the ratio is 0.7 to 2.5% by volume with respect to the whole friction material. As can be seen from the above, it is possible to suppress excessive wear of the mating material under severe usage conditions.
Further, the potassium titanate fiber or whisker containing iron contained as the fiber base material has particularly high heat resistance and therefore has excellent wear resistance at high temperatures (however, the attacking property of the mating material is small). Therefore, the decrease in the wear resistance of the friction material itself due to the reduction of the compounding ratio of antimony trisulfide is compensated by the composition of this potassium titanate fiber or whisker, so that the friction material itself under the severe use condition becomes excessive. Wear can be suppressed. In this way, it is possible to suppress both excessive wear of the friction material itself and the counterpart material when used under severe conditions.

Hereinafter, each component of the friction material according to the present invention, that is, the fiber base material, the resin binder, and the filler will be described in more detail.

The fibrous base material, that is, the fibrous base material which is a fibrous component forming the skeleton of the friction material, is as described above.
Potassium titanate fibers or whiskers containing iron are used as at least part. Here, the iron content is preferably about 0.1 to 2.0% by weight in terms of metal. Although this iron content is contained as an impurity (therefore, this fiber or whisker has a light yellow color), the more it is, the higher the heat resistance is in general, and the higher the wear resistance at high temperature is. However, conversely, the mechanical strength (tensile strength, bending strength) tends to decrease. Therefore, the iron content is preferably at least 0.1% by weight or more in order to effectively improve the heat resistance, but 2.0
It is preferable to limit the amount by weight.

The iron titanate-containing potassium titanate fiber or whisker sufficiently enhances the wear resistance of the friction material when used under harsh conditions (high heat) and prevents excessive wear. Generally, it is preferable to mix the friction material in a proportion of 5% by volume or more. The upper limit of the blending ratio is not particularly limited, and is generally 35% by volume, including the case of using it alone as a fiber base material.
It can be used in proportions up to. However, since it is difficult to satisfy all the properties required as a friction material with this potassium titanate fiber or whiskers alone,
It is preferably used in combination with other fibrous materials.

Examples of such fiber materials include organic fibers such as aramid fibers, novoloid fibers, nylon fibers and rayon fibers, inorganic fibers such as carbon fibers and glass fibers, or metal fibers such as whiskers, copper fibers and brass fibers. Can be mentioned. Further, while these fibrous materials including potassium titanate fibers or whiskers are non-abrasive (there is no or little aggression against the mating material), abrasive hard inorganic fibers can also be used.

This abrasive hard inorganic fiber corresponds to a fibrous form of an abrasive agent in powder form, and has a hardness higher than that of potassium titanate fiber or whisker having a Mohs hardness of 4, and therefore 4.5 or more. It has a Mohs hardness. Specific examples thereof include slag wool, rock wool, alumina-silica fiber, silica fiber, alumina fiber, carbide or nitride fiber, and whisker. And, by blending these abrasive hard inorganic fibers, not only can the friction coefficient of the friction material be increased similarly to the abrasive agent, and the surface of the mating material can be cleaned, but the strength, heat resistance and resistance of the friction material can be improved. Wearability and the like can be improved. As the abrasive hard inorganic fiber,
Since the smaller the fiber diameter, the less aggressive the mating material is, the alumina-silica system having an average fiber diameter of 1.0 to 4.5 μm is more preferable than those having an average particle diameter of 5.0 μm or more such as slag wool and rock wool. It is especially preferred to use ceramic fibers such as fibers or whiskers. The compounding ratio of the abrasive hard inorganic fiber is arbitrary, but generally it can be about 5 to 50% by volume with respect to the entire fiber base material.

A preferred example of the fiber base material is a combination of aramid fiber or other heat resistant organic fiber, potassium titanate fiber or whisker containing iron as described above, and abrasive hard inorganic fiber. be able to. According to this, it is possible to obtain a friction material that is well balanced in strength, weight, heat resistance and the like. In addition, non-ferrous metal fibers such as copper fibers may be further added to the combination of the fiber base materials in order to appropriately adjust the thermal conductivity of the friction material and improve the fade resistance.

Although the above example is an example of forming the friction material as a non-steel type friction material, steel fiber or stainless steel fiber may be used as the fiber base material. When this steel fiber is used as the main material of the fiber base material, the friction material is formed as a semi-metallic friction material, but in this case, it contains the above-mentioned iron component blended as a part of the fiber base material. The potassium titanate fiber or whisker that acts does not increase the wear resistance of the friction material itself, but rather acts to suppress the wear of the mating material.

Next, as the resin binder, phenol resin, melamine resin, epoxy resin, polyimide resin,
A polyester resin, rubber such as SBR, or the like can be used. Among these, the phenol resin or its modified product is the most commonly used one and is preferable. This phenol resin is generally used as a powder (novolak type).

As the filler which is a powdery component,
In addition to the above antimony trisulfide, other solid lubricants such as graphite, body fillers such as barium sulfate and calcium carbonate, organic dust such as cashew dust and other organic polymer powders, mainly heat Metal powders such as copper powder, zinc powder, and brass powder for improving conductivity, abrasive agents, and other additives can be used.

Here, the antimony trisulfide Sb ₂ S ₃ is
As described above, the wear resistance of the friction material is enhanced especially under high load conditions. Therefore, this antimony trisulfide is generally used together with graphite for improving wear resistance mainly under low load and medium load conditions. However, the mixing ratio is 0.
It is 7 to 2.5% by volume. If it is less than 0.7% by volume, the amount of wear of the friction material becomes excessive under particularly high load conditions, and the friction material can be prepared by blending iron-containing potassium titanate fiber or whiskers. It becomes difficult to suppress the excessive wear of. On the contrary,
If it is more than 2.5% by volume, the amount of wear of the mating material increases excessively.

As the abrasive agent for increasing the friction coefficient of the friction material, hard inorganic powder having a Mohs hardness of 5 or more can be generally used. Specifically, silica powder, alumina powder, zirconium oxide can be used. , Zirconium silicate and the like. These abrasives may be used alone or in combination of two or more thereof, but when abrasive hard inorganic fibers are used as the fiber base material, they are rather auxiliary. Is used for. In other words, the improvement of the friction coefficient due to the addition of the hard abrasive inorganic fiber is in a capped state if the content exceeds a certain limit even if the mixing ratio is increased. Therefore, the abrasive is used to supplement it.

However, when the friction material is used under particularly severe conditions, the abrasiveness of the abrasive increases exponentially under high heat, causing excessive wear of the mating material. It can be a cause. Therefore, as in the case of the abrasive hard inorganic fiber, the abrasive used is preferably the smaller the particle size, the less the attacking property of the mating material, and generally the average particle size is preferably about 1 to 10 μm. Further, it is preferable that the blending ratio thereof is relatively small, and the blending ratio in combination with the abrasive hard inorganic fiber, that is, the ratio of the components having a Mohs hardness of 4.5 or more in the friction material,
It is preferably about 3 to 20% by volume, and more preferably 3 to 17% by volume. As a result, excessive wear of the mating material can be more reliably suppressed and prevented.

A friction material comprising the above-mentioned fiber base material containing potassium titanate fibers or whiskers containing iron, a resin binder, and a filler containing antimony trisulfide in a specific ratio is usually heat-treated. It can be produced by a molding method, that is, by mixing the components, preforming the mixture, and then heat-pressing.

[0031]

EXAMPLES Examples of the present invention will be described below together with comparative examples.

FIG. 1 is a table showing the composition of the friction material of the embodiment of the present invention and the evaluation test results. FIG. 2 is a table showing the composition of the friction material of the comparative example and the evaluation test results.

[Preparation of Friction Material (Pad)] Friction materials of Examples 1 to 6 of the present invention were prepared with the compounding composition (volume%) shown in FIG. Further, for comparison with these examples, friction materials of Comparative Examples 1 to 6 were also produced with the compounding composition (volume%) shown in FIG. The friction materials of these examples and comparative examples are specifically embodied as a pad for a disc brake of an automobile.

As shown in FIG. 1, the friction materials (disc brake pads) of Examples 1 to 6 of the present invention are formed by including a fiber base material, a resin binder, and a filler. The fibrous base material forming the skeleton of the friction material is 15% by volume of aramid fiber as a main material, potassium titanate whiskers for ensuring heat resistance and abrasion resistance, and ceramics which are abrasive hard inorganic fibers. 10% by volume of wool and 3% by volume of copper fiber
It consists of The ceramic wool as the abrasive hard inorganic fiber is specifically a silica-alumina ceramic fiber (Mohs hardness 6, average fiber diameter 2.1).
μm, average fiber length 150 μm), and is added to supplement the strength, heat resistance and wear resistance of the friction material and to increase the friction coefficient due to its abrasiveness. Further, the copper fiber is for increasing the thermal conductivity of the friction material to an appropriate degree and for improving the fade resistance, and is rather added as an additive.

Here, as the potassium titanate whiskers, three types of A, B and C having different iron contents are used. That is, potassium titanate whisker A contains 1.0 volume% of iron in terms of metal, and potassium titanate whisker B contains 0.4 volume% of iron in terms of metal. Further, potassium titanate whisker C contains almost no iron (and other components): [iron content of potassium titanate whiskers A, B, C] A = 1.0 wt% B = 0.4 wt% C = 0.0 wt% Then, in Example 1 and Examples 4 to 6, 15 vol% of potassium titanate whisker A was blended, and in Example 2, 15 vol% of potassium titanate whisker B was blended. In Example 3, potassium titanate whiskers A and iron titanate-containing potassium titanate whiskers C were mixed in an amount of 5% by volume each (total amount: 10% by volume).

As described above, the fiber base material is mainly composed of aramid fiber which is a heat resistant organic fiber, potassium titanate whisker, and ceramic wool which is an abrasive hard inorganic fiber, and contains steel fiber. Not not. Therefore, the friction material of this embodiment is formed as a non-steel friction material.

Further, a phenol resin (powder) is used as the resin binder, and is blended in an amount of 17% by volume in each example. The blending amount is the same in the comparative example.

Further, as the filler, cashew dust,
Graphite as a solid lubricant and antimony trisulfide Sb ₂ S ₃ , zirconium silicate ZrSiO ₄ as an abrasive, slaked lime for maintaining the alkalinity of the friction material and enhancing its rust prevention, and as a body filler Barium Sulfate is used. Among these, 17% by volume of cashew dust, 5% by volume of graphite, and 3% by volume of slaked lime were blended in the same proportion in each example (and comparative example), and antimony trisulfide Sb ₂ S ₃ and zirconium silicate were mixed. ZrSiO ₄ is blended in different proportions. The blending ratio of barium sulfate is adjusted to the remaining volume%.

That is, the antimony trisulfide Sb ₂ S ₃ is 1.5% by volume in Examples 1 to 3 and 6, is 0.7% by volume in Example 4, and is 5% in Example 5. 2.5% by volume each.

Further, zirconium silicate ZrSiO
₄ , 3 types of A, B and C having different average particle sizes are used: [Average particle size of zirconium silicates A, B and C] A = 1 μm B = 10 μm C = 30 μm and Examples 1 to 5 3% by volume of zirconium silicate A and 7% by volume of zirconium silicate B in Example 6.

In contrast to the blended compositions of Examples 1 to 6, Comparative Examples 1 to 6 have the following blended compositions, respectively.

In Comparative Example 1, the types of potassium titanate whiskers were changed. In the composition of Examples 1 and 2, the iron titanate whiskers A and B were replaced with almost no iron. The same amount of potassium titanate whisker C was used at 15% by volume.

In Comparative Examples 2 to 4, the amount of antimony trisulfide added was changed in the composition of Example 1. In Comparative Example 2, the amount of antimony trisulfide added was relatively increased to 3.0% by volume, and in Comparative Example 3, it was decreased to 0.5% by volume.
Then, no antimony trisulfide was added. The mixing ratio of barium sulfate is adjusted according to the mixing ratio of these antimony trisulfides.

Further, Comparative Example 5 is the same as Comparative Example 4 in which antimony trisulfide was not blended, but the blending ratio of the ceramic wool, which is an abrasive hard inorganic fiber, was increased to 15% by volume, and the silicic acid which was an abrasive agent was used. The compounding ratio of zirconium A was also increased to 7% by volume (thereby, barium sulfate was reduced to 3% by volume). Similarly, Comparative Example 6 is the same as Comparative Example 4 except that the type of zirconium silicate is changed and 3% by volume of zirconium silicate C having a large average particle diameter is mixed.

Then, the friction materials (disc brake pads) of Examples and Comparative Examples having these compounding compositions were produced by the usual thermoforming method, specifically as follows. That is, the friction material raw material having the above-mentioned predetermined composition is sufficiently uniformly mixed with a V-type blender, and then the powder mixture is put into a preforming die, and 200 kg / c at room temperature.
Pre-molding was performed by applying a pressure of m ² for 1 minute. Next, the preform of this friction material was set in a thermoforming die together with a back metal whose surface was previously coated with a phenolic resin adhesive,
Thermoforming was performed at a pressure of 0 kg / cm ² and a temperature of 160 ° C. for 10 minutes. Then, this was further heat-treated at 250 ° C. for 120 minutes to obtain a friction material and a disc brake pad integrated with the back metal.

[Evaluation Test] Next, an evaluation test was carried out on the wear resistance and the mating material wear resistance (aggression) of each of the friction materials (disk brake pads) produced in these Examples and Comparative Examples. .

In this test, specifically, each friction material is attached to a brake dynamometer to perform a braking test, and the abrasion amount of the friction material and the abrasion amount of the mating material (disk rotor) after the braking test are completed are shown. It was measured. Then, this braking test was conducted under the following relatively severe conditions.

Caliper brake model used: PE54-2
2V (steel) inertia: 5.5kgf ・ m ・ s ² Temperature before braking: 300 ° C Initial speed of braking: 200km / h Speed after deceleration: 100km / h Deceleration: 0.35G Number of brakings: 20 times That is, friction material The surface is preheated to 300 ℃, and the speed is 2
Braking from 00 km / h to 100 km / h was repeated 20 times.

The measured wear amount of the friction material (pad wear amount) mm at this time and the wear amount of the mating material (rotor wear amount) μm
Are shown together with FIG. 1 and FIG.

[Test Results] As shown in FIGS. 1 and 2, under the severe braking conditions as described above, the friction materials (disc brake pads) of Comparative Examples 1 to 6 all showed a wear amount. It tends to be excessive or the amount of wear of the mating material (disk rotor) is excessive. On the other hand, in the friction materials of Examples 1 to 6, both the wear amount of the friction material itself and the wear amount of the mating material are suppressed to good levels.

Looking at the types of potassium titanate whiskers, in Comparative Example 1 using potassium titanate whiskers C containing almost no iron, the friction material (pad) itself has a large amount of wear, and the polishing property is high. Despite the fact that ceramic wool, which is a hard inorganic fiber, and zirconium silicate, which is an abrasive, are mixed, the friction material component is adhered to the mating material (rotor). On the other hand, in Examples 1 and 2 using the potassium titanate whiskers A and B containing iron, the wear amount of the friction material was small and the wear amount of the mating material was also small. Further, also in Example 3 in which potassium titanate whisker A and potassium titanate whisker C were used in combination, wear of both the friction material and the mating material was small.

Therefore, from these Examples 1 to 3 and Comparative Example 1, in order to suppress both excessive wear of the friction material and the mating material under particularly severe braking conditions, at least a part of the fiber base material is used. It can be seen that it is preferable to use a potassium titanate whisker or fiber containing iron. Also, from the mutual comparison of Examples 1 to 3, as the iron content contained in the potassium titanate whisker or the fiber was relatively large, and the compounding ratio of such potassium titanate whisker or the fiber was large, the wear was decreased. It can also be seen that it can be suppressed more.

Further, regarding the blending ratio of antimony trisulfide Sb ₂ S ₃ used together with graphite as a solid lubricant, when it was not blended, as in Comparative Example 4, under particularly severe braking conditions. Is extremely worn. On the other hand, by adding antimony trisulfide, the wear resistance of the friction material is improved, and the wear resistance tends to be improved as the proportion of antimony trisulfide is increased.
That is, the wear amount of the friction material was 0.5% by volume in Comparative Example 3, 0.7% by volume in Example 4, 1.5% by volume in Examples 1 to 3,
Then, it decreases in the order of 2.5% by volume of Example 5. However, conversely, the greater the proportion of antimony trisulfide, the greater the amount of wear of the mating material, especially 3.0% by volume.
In Comparative Example 2, which is the blending ratio of, the amount of wear increases rapidly.

From these Examples 1, 4, and 5 and Comparative Examples 2 to 4, it is found that the compounding ratio of antimony trisulfide is preferably 0.7 to 2.5% by volume. It should be noted that if the mixing ratio is 0.5% by volume (Comparative Example 3), the amount of wear of the friction material is relatively large and the wear resistance is not sufficient, which is not preferable.

Regarding Comparative Example 5, Comparative Example 4
From the comparison with the above, it is understood that the wear amount of the friction material itself can be reduced by increasing the mixing ratio of the ceramic wool which is the abrasive hard inorganic fiber and the zirconium silicate which is the abrasive. However, in this case, the wear of the mating material significantly increases. The wear of the mating material is further increased when antimony trisulfide is added.

In Comparative Example 6, zirconium silicate C having an average particle diameter of 30 μm was used as an abrasive, and according to this, a comparative example using zirconium silicate A having an average particle diameter of 1 μm was used. From the comparison with Example 4, Comparative Example 5
It is understood that the wear of the friction material can be reduced as in the case of. However, also in this case, as in Comparative Example 5, the wear of the mating material significantly increases. The excessive wear of the mating materials in Comparative Examples 5 and 6 was because the aggressiveness of the abrasive agent (and the abrasive hard inorganic fiber) increased exponentially due to high heat under severe braking conditions. Seem.

For Comparative Example 5 and Comparative Example 6,
In Examples 1 to 5 using zirconium silicate A having an average particle size of 1 μm and Example 6 using zirconium silicate B having an average particle size of 10 μm, the wear of the mating material is suppressed to a low level. Therefore, under the condition of using potassium titanate whiskers or fibers containing iron and compounding antimony trisulfide in a specific ratio, as an abrasive,
It can be seen that it is preferable that the particle size is relatively small and the average particle size is about 1 to 10 μm. Further, regarding the compounding ratio of the abrasive and the hard abrasive inorganic fiber, the total amount thereof is preferably at least about 20% by volume or less, and more preferably 17% by volume or less in Example 6.

As described above, the friction materials (disc brake pads) of Examples 1 to 6 of the present invention contained potassium titanate fibers or whiskers containing iron as the fiber base material, and contained three parts. Antimony sulfide is mixed in a relatively small specific ratio, that is, in a ratio of 0.7 to 2.5% by volume with respect to the entire friction material. Therefore, it is possible to suppress excessive wear of the friction material itself and the mating material under particularly severe conditions of use, and also to maintain the wear at good levels. Further, in this case, as the abrasive agent made of zirconium silicate, the one having a relatively small particle diameter and an average particle diameter of 1 to 10 μm is used. Therefore, the total amount of the abrasive agent and the abrasive hard inorganic fiber is further mixed. Since the ratio is relatively small, it is possible to more reliably prevent excessive wear of the mating material. Therefore, these friction materials can be particularly preferably used for an automobile that runs at high speed and repeats severe braking. However, it is needless to say that it can be suitably used as a highly safe friction material even for general automobiles.

By the way, in this embodiment, the abrasive hard inorganic fiber is blended as a part of the fiber base material to secure the friction coefficient of the friction material, and the abrasive agent is also blended. One composition can be omitted as appropriate by increasing the other composition. However, the abrasive hard inorganic fiber is preferable in that it has good retainability in the friction material and also has the effect of increasing the strength of the friction material.
Abrasive agents are also preferred to supplement and secure the required friction coefficient. So these are
If the fiber diameter and the particle diameter are sufficiently small, the aggressiveness against the mating material is also small, so that it is preferable to use them together as in this example.

Further, in this embodiment, the non-steel friction material which does not completely contain the steel fiber was formed as the fiber base material. However, if necessary, the steel fiber is used as the fiber base material, and the low steel friction material, Alternatively, it may be formed as a semi-metallic friction material.

Further, although the friction material of the present invention has been described by taking the disc brake pad as an example, the present invention is not limited to this, and the lining of the drum brake, the clutch facing, etc. It can be applied to various friction materials.

[0062]

As described above, the friction material according to the present invention is a friction material containing a fibrous base material, a resin binder, and a filler such as a solid lubricant. Containing potassium titanate fibers or whiskers containing 0.7 to 0.7 to the entire friction material as a solid lubricant.
It contains 2.5% by volume of antimony trisulfide.

Therefore, according to this friction material, since the solid lubricant antimony trisulfide is mixed in a relatively small proportion, for example, when the braking is repeated at a speed close to 200 km / hour, it is severe. It is possible to suppress excessive wear of the mating material under use conditions. On the other hand, the decrease in the wear resistance of the friction material itself due to the reduction of the compounding ratio of antimony trisulfide is compensated by the compounding of iron titanate titanate fibers or whiskers containing iron having excellent heat resistance. It is also possible to suppress excessive wear of the friction material itself under severe operating conditions.
That is, according to the friction material of the present invention, there is an effect that both excessive friction of the friction material itself and the counterpart material when used under severe conditions can be suppressed.

[Brief description of drawings]

FIG. 1 is a table showing a compounding composition of a friction material (disc brake pad) of an example of the present invention and an evaluation test result.

FIG. 2 is a table showing a compounding composition of a friction material (disc brake pad) of a comparative example and an evaluation test result.
(Note that in the compositions of FIGS. 1 and 2, the potassium titanate whiskers A, B, and C have different iron contents, and A = 1.0 w
t%, B = 0.4 wt%, and C = 0.0 wt%. Further, zirconium silicates A, B and C have different average particle diameters, A = 1 μm, B = 10 μm and C = 30 μm. )

Claims (1)

[Claims] 1. A friction material comprising a fibrous base material, a resin binder, and a filler such as a solid lubricant, wherein the fibrous base material contains potassium titanate fibers or whiskers containing iron. As the solid lubricant, 0.7 to
A friction material comprising 2.5% by volume of antimony trisulfide.