JP2002097452A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material lowered in attacking properties on an aluminum alloy rotor in particular and not affected by a pedal operating force or a vehicle speed. SOLUTION: This friction material is obtained by compounding and molding a base fiber, a binding material, a friction modifier and a filler and is used in combination with a rotor made of an aluminum alloy, where the friction modifier is obtained by granulating a hard inorganic powder and a solid lubricating material via a thermosetting resin binder and is dispersed in the friction material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a friction material used in combination with a cast iron rotor or an aluminum alloy rotor.

[0002]

2. Description of the Related Art In recent years, in consideration of environmental issues and the like, development in consideration of environmental protection has been promoted in the field of automobiles, and electric vehicles and hybrid cars have been commercialized.

Under these circumstances, the use of a motor in an automobile has reduced the load on the brake, and one of the requirements for reducing the weight of the vehicle is to reduce the weight of brake parts. Conventionally, cast iron has been used as a material for a disk rotor of a disk brake of an automobile. However, there is a movement to adopt an aluminum alloy having a very small specific gravity as compared with cast iron as a disk rotor in order to meet the demand for weight reduction.

[0004] The friction material adapted to the reinforced aluminum alloy rotor is different from the friction material for the conventional cast iron rotor,
It is known that very large amounts of grinding components need to be used. It has been known that it is necessary to add a considerable amount of lubricating component to the friction material at the same time as adding a grinding component to the friction material, in order to prevent counterpart attacks. The quantity and the presence of both are important factors.

When a friction material containing a large amount of a grinding component and a lubricating component is produced by a conventional production method, aggregates of the grinding component and the lubricating component are easily formed in the friction material, and the grinding component and the lubricating component are not uniform. It was easy to become what existed. The presence of such aggregates not only increases the fluctuation of the friction coefficient μ that affects the braking effect, but also causes a phenomenon in which a part of the mating material (rotor) is abnormally intensively worn, and the grinding component and the lubrication component work well. I had the problem of not meeting each other.

Japanese Unexamined Patent Publication (Kokai) No. 6-228538 discloses a non-asbestos-based friction material using a hard inorganic material having a Mohs' hardness of 6 or more as a friction material used in combination with an aluminum alloy rotor. Also in this case, when a friction material containing a hard inorganic material as a grinding component and a lubricating component is manufactured, aggregates of a grinding component and a lubricating component are easily formed in the friction material, and both components are non-uniformly present. However, there was a problem that the addition effect was not always obtained.

A conventional friction material for a cast iron disk brake is a component that requires a predetermined friction coefficient (μ) under a wide range of brake use conditions. Extensive braking conditions include climatic factors such as temperature, humidity, rainfall, treading power, vehicle speed,
User factors such as maintenance cycle and frequency, road conditions such as submergence and snow melting salt, and infrastructure factors such as the degree of pavement can be cited.

Accordingly, among the friction materials, a friction material which is hard to affect the pedaling force (oil pressure) and the vehicle speed at the most basic position of the brake is required.

Hitherto, in order to reduce the influence of the pedaling force and the vehicle speed, it has been studied how to make the compounding material uniform. For example, in Japanese Patent Application Laid-Open No. 2-298576, the composition of the friction material is set to 50 μm or more. There is a disclosure of a friction material that is made into an integrated premixed particle and contains an appropriate amount of the integrated premixed particle.

However, at present, the above-mentioned problems have not been sufficiently solved even if the mixing material is actually used as premixed particles to achieve uniform dispersion.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and reduces the aggressiveness of a friction material by forming a friction material in which a hard cutting component and a lubricating component coexist closely. It is an object to reduce the frictional force and to make the friction material less affected by the pedaling force and the vehicle speed.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems. As a result, the hard inorganic powder and the solid lubricating component, which are the grinding components randomly present in the friction material, respectively. The present inventors have found that the above-mentioned counterpart aggressiveness can be reduced and the braking performance can be improved by granulating the same through a phenol resin and dispersing the same in a friction material, thereby completing the present invention.

The first friction material of the present invention is a friction material which is obtained by compounding and molding a base fiber, a binder, a friction modifier and a filler, and used in combination with an aluminum alloy rotor. ,
A friction material, wherein a hard inorganic powder and a solid lubricant are granulated via a binder of a thermosetting resin and are dispersed in the friction material.

The hard inorganic powder preferably has a Mohs hardness of 6 or more.

The second friction material of the present invention is a friction material obtained by compounding and molding a base fiber, a binder, a friction modifier, and a filler, and used in combination with a cast iron rotor, The friction modifier is characterized in that a hard inorganic powder and a solid lubricant are granulated via a binder of a thermosetting resin and are dispersed in the friction material.

The granulated product of the hard inorganic powder and the solid lubricant preferably has an average particle size of 10 μm to 1000 μm.

[0017] The above-mentioned granulated product contains 50 to 7 hard inorganic powders.
0 volume%, solid lubricant 15-25 volume%, binder 1
It is preferably from 5 to 25% by volume.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The first friction material of the present invention is directed to a friction material used in combination with an aluminum alloy rotor, and includes a base fiber, a binder, a friction modifier, It is formed by compounding with a filler. And, in the friction modifier, the hard inorganic powder and the solid lubricant serving as the grinding components are granulated via the binder of the thermosetting resin, and are dispersed in the friction material together with other organic dusts and metal powders. . The aluminum alloy that constitutes the aluminum alloy rotor contains a hard material for strengthening, so it is necessary to use a large amount of hard inorganic powder grinding components for the corresponding friction material. In order to prevent the aluminum alloy from being attacked and worn, it is necessary to coexist a considerable amount of lubricating components. However, these two components can exhibit the performance as a friction material by complementing each other's characteristics.

Therefore, in the present invention, in order to prevent the grinding component and the lubricating component from agglomerating, the two components are mixed, fixed and fixed with a thermosetting resin to form an integrated granulated material, thereby always grinding. The component and the lubricating component are in a state of being adjacent to each other, and the effects of both can be always exerted on the friction surface.

The mixture of the grinding component and the lubricant powder can be granulated by using a fluidized bed granulator.
Specifically, a mixture obtained by mixing a hard inorganic powder and a solid lubricant powder having a predetermined ratio of a grinding component in the fluidized bed granulator is stirred and circulated as a fluidized bed of the powder by an introduced air flow, and the circulating flow is performed. A mold fluidized bed is formed. A liquid binder (such as phenolic resin) is sprayed into the circulating fluidized bed to combine the two components of the fluidized bed, and a mixture particle is grown to form a granulated product having a desired particle size. Can be manufactured. At this time, the particle size of the granulated material can be changed depending on the degree of fluid mixing and the spray state of the binder. The obtained granulated material hardens the binder sufficiently by heating or the like to obtain a granulated product in which a grinding component and a lubricating component exhibiting an effect as a friction modifier coexist.

As the hard inorganic powder as a grinding component constituting the granulated material, alumina, silica, silicon carbide, zirconium oxide, or the like having a Moh's hardness of 6 or more can be used.

On the other hand, as the lubricating component, a general solid lubricant can be used. Specifically, graphite, metal sulfides such as molybdenum, antimony, and zinc can be used.

As the binder, a thermosetting resin can be used, for example, a liquid phenol resin can be used.

The composition of the granulated product is such that the amount of the hard inorganic material powder is 50 to 70% by volume when the granulated material is 100% by volume.
More preferably 60 to 65% by volume, the amount of solid lubricant is 15 to 25% by volume, more preferably 18 to 22% by volume.
And the binder is preferably 15 to 25% by volume, more preferably 17% by volume.
~ 20% by volume.

When the mixing ratio of the granulated material is within the above range, the effect of granulation is most exhibited. When the amount of the hard inorganic material powder is less than 50% by volume, the grinding component is insufficient and the friction coefficient is lowered, which is not preferable.
Exceeding the ratio is not preferable because the lubricating components and the binder are insufficient and the desired effects cannot be obtained. If it is outside the above range, it is impossible to prevent the friction material from abrading the rotor of the aluminum alloy or from having an insufficient friction coefficient.

The average particle size of the granulated product is 10 μm to 10 μm.
More preferably, it is in the range of 00 μm. When the average particle diameter is smaller than 10 μm, the effect of the granulated material is small. On the other hand, if it is larger than 1000 μm, the specific gravity of the granulated material increases, and the granulated material is unevenly distributed in the friction material, which is not preferable.

When only the hard inorganic material acts alone in the friction material, the rotor, which is the mating material, is partially attacked and the rotor is worn. However, since the solid lubricant is always present near the hard inorganic powder, the surface of the rotor is hardly affected. A lubricating film can be formed on the surface, and partial attack of the friction material on the rotor can be suppressed.

As described above, since the hard inorganic powder and the solid lubricant always act on the rotor surface at the same time, the friction coefficient of the friction material is slightly reduced as compared with the case where no granulated material is present. Since it is always formed on the rotor surface, the coefficient of friction can be stabilized even in an aluminum alloy rotor.

The friction material can be formed by mixing a usual base fiber with a binder, a granulated material, an organic dust as a friction modifier, a metal powder, a filler and the like.

As the base fiber, aramid fiber, rock wool, ceramic wool, glass fiber, potassium titanate fiber, silicon calcium fiber and the like are used. The amount of the base fiber is 10 to 30% by volume, more preferably 15 to 30% by volume.
25% by volume.

As a friction modifier. In addition to the granulated material, organic dust cashew dust, rubber dust and the like can be used. 10 to 30% by volume, more preferably 13 to 25% by volume
It is. Further, copper, brass, zinc, iron and the like can be used as the metal powder. The amount of metal is 1 to 10% by volume, more preferably 2 to 6% by volume. Barium sulfate,
Calcium carbonate, mica, kaolin, talc, etc. can be used. The amount of the filler is preferably in the range of 0 to 40% by volume. Further, a phenol resin, a urea resin, a melamine resin, an epoxy resin, a urethane resin, a polyimide resin, or a modified resin thereof can be used as the binder. The amount of binder is from 10 to 30% by volume, preferably from 15 to 20% by volume. This amount represents the amount when the entire friction material is 100% by volume. In addition, it is preferable that the added amount of the granulated material is 0 to 30% by volume of the granulated material when the friction material is 100% by volume. If the added amount of the granulated material is less than 10% by volume, the effect of adding the granulated material is not recognized.

The friction material can be produced by mixing the above-mentioned components, disposing the mixture in a mold as in a usual production method, and pressurizing and heating.

The second friction material of the present invention is of a type used in combination with a cast iron rotor.

Instead of granulating all the components of the friction material in advance, a solid lubricant and a hard inorganic powder, which most affect the friction coefficient, are granulated and blended into the friction material. In this granulated material, a lubricant is arranged near the hard inorganic powder which increases the coefficient of friction. By using such a granulated material as one of the components of the friction modifier of the friction material, not only the dependence on the vehicle speed and the pedaling force (= oil pressure) is reduced, but also the change in the friction coefficient during one braking is reduced. A stabilized friction material can be obtained.

As described above, the granulation of the grinding component and the lubricating component is performed as follows.
Hard inorganic powder has Mohs hardness of 6 or more and average particle size of 1
By setting the thickness to 0 μm to 1000 μm, the grinding component and the lubricating component are always present in the vicinity, and a friction material that can always exert the effects of both components can be obtained.

As the hard inorganic powder, those having a Mohs hardness of 6 or more, such as alumina, silica, silicon carbide and zirconium oxide, can be used.

As the solid lubricant, a general solid lubricant can be used. Specifically, graphite, metal sulfides such as molybdenum, antimony, and zinc can be used.

The granulated material is composed of a binder of a thermosetting resin such as a phenol resin, a solid lubricant such as graphite and metal sulfide, and a hard inorganic powder which is a grinding component such as zirconium silicate and iron oxide powder. Is appropriately blended and granulated and solidified to be blended with the friction material.

The thermosetting resin used for the granulating binder is as follows:
A phenol resin was used, and only the hard inorganic powder was used in powder form. If it is fibrous, the directionality of the fiber affects the friction coefficient of the friction material, which not only does not solve the problem, but also causes a manufacturing problem that granulation cannot be performed well. The hard powder preferably has a Mohs hardness of 6 or more.
If the hardness is less than 6, a predetermined coefficient of friction cannot be obtained. Specific examples include zirconium oxide, zirconium silicate, silica, iron oxide powder, alumina, and silicon carbide.

The particle size of the granulated product is 10 μm to 1000 μm
Is preferred. If it is less than 10 μm, the effect of the granulated material is small. On the other hand, if it is larger than 1000 μm, the specific gravity of the granulated material becomes large, and the granulated material itself is not preferable because segregation occurs in the friction material.

The amount of the granulated material was 100% by volume of the friction material.
It is preferable that the granulated material contains 10 to 30% by volume. If the amount of the granulated material is less than 10% by volume, the effect of adding the granulated material is not recognized, and if it is more than 30% by volume, other properties as a friction material are not sufficient, which is not preferable.

When the friction material of the present invention is combined with a cast iron rotor, not only the dependence on the vehicle speed and the treading force (= hydraulic pressure) is reduced, but also the change in the friction coefficient during one braking is reduced and the friction material is stabilized. Can be.

[0043]

The present invention will be specifically described below with reference to examples.

(Example 1) As a granulated product, silicon carbide and graphite were charged into a fluidized-bed granulator at a ratio of 10: 4, and a liquid phenol resin was sprayed into a place where the material was circulated by an air flow. , And a combined granulated product having an average particle size of 330 µm was prepared.

Next, 15 volume% of aramid fiber, 16 volume% of phenol resin, 15 volume% of dust, 10 volume% of inorganic fiber (potassium titanate fiber), 30 volume% of inorganic filler (barium sulfate), carbonization of hard inorganic powder A granulated product comprising 10% by volume of silicon and 4% by volume of graphite of a solid lubricant was mixed with a mixer for 10 minutes to obtain a mixture. This mixture is
It was put into a mold at 60 ° C., and was heated and pressed at a pressure of 30 MPa for 10 minutes. After molding, heat treatment was performed in a furnace at 220 ° C. for 6 hours to obtain a friction material.

(Example 2) 10% by volume of silicon carbide and 4% by volume of molybdenum disulfide were added as granules to a fluidized-bed granulator, and a liquid phenol resin was sprayed in a place where the material was circulated, and the average was sprayed. A granulated product having a particle size of 300 μm was obtained. The friction material was manufactured in the same manner as in Example 1.

(Example 3) Granulated material was 10% by volume of alumina
And 4% by volume of graphite were put into a fluidized-bed granulator, and a liquid phenol resin was sprayed in a place where the material was circulating to produce a granulated product having an average particle diameter of 120 μm. The friction material was manufactured in the same manner as in Example 1.

Example 4 The granulated material was 10% by volume of alumina.
And 4% by volume of graphite were put into a fluidized-drier granulator, and a liquid phenol resin was sprayed in a place where the material was circulating to produce a granulated product having an average particle size of 810 μm. The friction material was manufactured in the same manner as in Example 1.

(Comparative Example 1) A friction material was produced in the same manner as in Example 1 except that silicon carbide and graphite were not granulated, but in the mixing ratio of Example 1.

(Comparative Example 2) Granules were placed in a fluidized-dry granulator at a ratio of zirconium oxide (Mohs hardness 6) 10 and graphite 4 and sprayed with a liquid phenol resin in a place where the material was circulated. A granulated product having a particle size of 540 μm was obtained.

Each of the obtained friction materials was evaluated as follows.

The measurement of the coefficient of friction was performed by setting the test environment at 23 ° C. × 65.
% Dynamometer JASO-C406
Carry out according to -82. The braking condition is 6 per hour
The measurement was performed at 5 km / h, deceleration of 0.53 G, and a temperature before brake of 120 ° C. Max. μ-Min. μ = △ μ was measured. The rotor used was an aluminum alloy rotor. The rotor wear was determined by measuring the abnormal wear portion on the rotor surface after the test by the ratio to the total sliding area. The wear of the friction material was measured from the thickness of the friction material. The results are shown in Table 1.

[0053]

[Table 1]

As shown in Table 1, in each of the examples in which the granulated material was blended, the characteristics of the average friction coefficient, the amount of wear, the abnormal friction, and the Δμ were different from those of Comparative Example 1 in which the granulated material was not formed. All are excellent.

When granulation was performed using zirconium oxide as the hard inorganic substance in Comparative Example 2, the average friction coefficient was slightly small.

(Example 5) As for the granulated material, zirconium silicate (Mohs hardness 7.0) and graphite were charged into a fluidized-dry granulator, and a liquid phenol resin was sprayed in a place where the material was circulated. Granules having an average particle diameter of 410 μm and 900 μm were produced.

Next, 15 volume% of aramid fiber, 16 volume% of phenol resin, 15 volume% of dust, 10 volume% of inorganic fiber (potassium titanate fiber), 30 volume% of inorganic filler (barium sulfate), carbonization of hard inorganic powder A granulated product comprising 10% by volume of silicon and 4% by volume of graphite of a solid lubricant was mixed with a mixer for 10 minutes to obtain a mixture. This mixture is
It was put into a mold at 60 ° C., and was heated and pressed at a pressure of 30 MPa for 10 minutes. After molding, heat treatment was performed in a furnace at 220 ° C. for 6 hours to obtain a friction material.

(Example 6) As a granulated product, iron oxide powder (Mohs hardness of 6.5) and molybdenum disulfide were charged into a fluidized-dry granulator, and a liquid phenol resin was added to a place where the granulated raw material was circulating. By spraying, a granulated product having an average particle size of 250 μm was prepared.

Example 7 Silicone carbide (Mohs hardness of 9.0) and antimony trisulfide were charged into a fluidized-dry granulator, and a liquid phenol resin was sprayed into a place where the raw materials were circulated. Then, a granulated product having an average particle size of 800 μm was prepared.

Comparative Example 3 A friction material was produced in the same manner as in Example 4, except that zirconium silicate and graphite were not used.

(Comparative Example 4) Zirconium silicate and graphite were charged into a fluidized-drier granulator, and a liquid phenol resin was sprayed in a place where the material was circulated, and small particles having an average particle diameter of 4 μm were obtained. Granules having a diameter were produced.

(Comparative Example 5) As granules, zirconium silicate and graphite were charged into a fluidized-dry granulator, and a liquid phenol resin was sprayed in a place where the material was circulated, and large particles having an average particle diameter of 1190 µm were obtained. Granules having a diameter were produced.

(Comparative Example 6) Magnesium oxide (Mohs hardness of 5.5) and graphite were charged into a fluidized-dry granulator, and a liquid phenol resin was sprayed in a place where the material was circulated to obtain an average particle size. A granulated product having a diameter of 540 μm was produced.

(Comparative Example 7) As for the granulated product, a potassium titanate powder (Mohs hardness of 4.0) and graphite were charged into a fluidized-dry granulator, and a liquid phenol resin was sprayed in a place where the material was circulated. A granulated product having an average particle size of 540 μm was prepared.

Evaluation of Performance of Friction Material The friction coefficient was measured according to a dynamometer JASO-C406-82 in which the test environment was constant at 23 ° C. × 65%. The braking conditions are 50, 100,
The measurement was performed at 130 km / h, a constant hydraulic pressure (1, 3, 6, 9 MPa), and a temperature before brake of 120 ° C. The oil pressure dependency of the friction coefficient is the maximum friction coefficient of braking at each speed. μ-Min. μ = △ μ was measured. The speed dependence of the friction coefficient is the maximum friction coefficient of braking at each oil pressure. μ-Min. μ = △ μ was measured. The rotor used was a cast iron rotor. The results are shown in Table 2.

[0066]

[Table 2]

As shown in Table 2, Examples 5 to 8 in which granules were blended were improved in comparison with Comparative Example 3 in terms of friction coefficient, oil pressure dependence of friction coefficient, and speed dependence of friction coefficient. . Comparative Example 4 is a case where the particle size of the granulated product is as small as 4 μm, and the effect as the granulated product is not sufficiently obtained. If the particle size of the granulated product of Comparative Example 5 is too large as 1190 μm, the addition effect cannot be sufficiently exhibited due to uneven distribution of the granulated product. Therefore, it can be seen that a range of the particle size of the granulated product from 10 to 1000 is effective. Further, in Comparative Examples 6 and 7, granules were formed using inorganic powders having Mohs hardnesses of 5.5, 4.0 and less than 6, so that if the hardness of the inorganic powder was low, the performance of the friction material was low. It can be seen that no improvement has been achieved. Therefore,
It shows that it is effective to use a hard inorganic powder having a Mohs hardness of 6 or more.

[0068]

The friction material of the present invention is applied to an aluminum alloy rotor by granulating hard inorganic powder as a grinding component and solid lubricant as a lubrication component and blending them as components of a friction modifier. It shows useful performance for friction characteristics, wear, etc. as a friction material. Furthermore, it is a friction material that exhibits a balanced friction performance as a friction material in the case of a cast iron rotor and can be used as a brake component that meets the needs of the times.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08J 5/14 CEZ C08J 5/14 CEZ C08K 7/02 C08K 7/02 9/08 9/08 C08L 101/00 C08L 101 / 00 F16D 69/02 F16D 69/02 CG (72) Inventor Yoshihide Yamada 1141 Okawagahara, Iino-shi, Fujioka-cho, Nishikamo-gun, Aichi Prefecture Aisin Chemical Co., Ltd. (72) Inventor Katsumi Uemura Kariya-shi, Aichi 2-1-1 Asahi-machi Aisin Seiki Co., Ltd. (72) Inventor Masaaki Kobayashi 2-1-1 Asahi-cho, Kariya-shi, Aichi F-term in Aisin Seiki Co., Ltd. 3J058 BA73 FA01 GA07 GA28 GA33 GA55 GA82 GA85 4F071 AA41 AA42 AA53 AA56 AA60 AB03 AB18 AB20 AB21 AB23 AB24 AB26 AB28 AB30 AD01 AE17 AG31 AH07 DA01 DA05 4J002 CC03X CC16X CC18X CD00X CK02X CL06W CM04X DA027 DE097 DE147 DE186 DE238 DG027 DG048 DJ006 FG048 DJ006 DJ007 dj048 DJ006 DJ007

Claims (5)

[Claims] 1. A friction material formed by compounding a base fiber, a binder, a friction modifier, and a filler, and used in combination with an aluminum alloy rotor, wherein the friction modifier comprises: A friction material, wherein a hard inorganic powder and a solid lubricant are granulated via a binder of a thermosetting resin, and are dispersed in the friction material. 2. The friction material according to claim 1, wherein the hard inorganic powder has a Mohs hardness of 6 or more. 3. A friction material obtained by compounding and molding a base fiber, a binder, a friction modifier, and a filler, and used in combination with a cast iron rotor. A friction material, wherein an inorganic powder and a solid lubricant are granulated via a binder of a thermosetting resin, and are dispersed in the friction material. 4. The friction material according to claim 3, wherein the granulated product of the hard inorganic powder and the solid lubricant has an average particle size of 10 μm to 1000 μm. 5. The granulated product according to claim 1, wherein the hard inorganic material powder is 50 to 7%.
0 volume%, solid lubricant 15-25 volume%, binder 1
The friction material according to claim 1, wherein the content is 5 to 25% by volume.