JP2001027271A - Friction material - Google Patents

Abstract

(57) [Problem] To secure a large friction coefficient and a high shear strength by using an organic paper-like base material. A paper-like substrate made of a fibrous material, a composite binder formed from at least one of a metal alkoxide and an organic group-substituted metal alkoxide and impregnated into the substrate,
And a phenolic resin impregnated in a substrate.
Since the composite binder is exposed on the surface of the base material, the friction characteristics of the composite binder are exhibited during friction, and the boundary friction coefficient becomes large. In addition, the presence of the phenolic resin improves the permeability of the composite binder to the base material, and provides high shear strength. Further, the presence of the phenolic resin improves the flexibility as compared with the case of using only the composite binder, so that the followability to the mating material is improved, and the friction coefficient is further improved by increasing the contact area.

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 for clutch facing of a power transmission system of an automobile, an industrial machine, a railway vehicle, and the like. The friction material of the present invention,
It is particularly useful as a wet friction material used in oils.

[0002]

2. Description of the Related Art As a friction material used for facing of a wet clutch, for example, as disclosed in Japanese Patent Publication No. 58-47345, an organic fiber is used as a base material, and various friction modifiers are blended with the organic fiber. In addition, paper-based friction materials obtained by impregnating and solidifying a binder made of a thermosetting resin such as a phenol resin are often used.

However, the above-mentioned friction material has a problem that heat resistance is low and a friction coefficient is small because the paper-like base material and the binder are both organic, and various measures have been taken to solve this problem. Has been taken.

As a countermeasure, for example, in clutch facing, the number of friction plates is increased or the area is increased. However, if you take such measures,
The wet clutch structure is complicated and large-scale, resulting in large energy loss and high cost.

Attempts have also been made to apply, for example, a copper-based sintered friction material to a wet clutch. If such a sintered friction material can be used, even if the number of friction plates is small and the area is small, the heat resistance and the pressure resistance can be satisfied, and the above problem can be solved. However, many sintered metal-based friction materials often have a friction coefficient smaller than that of organic friction materials, and their friction characteristics are insufficient for recent high performance wet clutches of automobiles.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to secure a large friction coefficient and a high shear strength by using an organic paper-like base material. .

[0007]

According to the first aspect of the present invention, there is provided a friction material comprising a paper-like base made of a fibrous material and at least one of a metal alkoxide and an organic group-substituted metal alkoxide. A composite binder formed and impregnated in a substrate, and a phenolic resin impregnated in a substrate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In a friction material of the present invention, a fibrous material constituting a paper-like base material is bonded to a composite binder and a phenolic resin. Accordingly, the composite binder exposed on the surface of the base material increases the boundary friction coefficient during friction. In addition, the presence of the phenolic resin improves the permeability to the base material, and provides high shear strength. Further, the presence of the phenolic resin improves the flexibility as compared with the case of using only the composite binder, so that the followability to the mating material is improved, and the friction coefficient is further improved by increasing the contact area.

When a friction material is prepared using only a composite binder, the metal skeleton of the composite binder is concentrated on the surface layer, so that although the friction coefficient is high, the strength at the central portion is weak and sufficient shear strength cannot be obtained. There was a problem.
However, by using the composite binder and the phenolic resin together, the metal skeleton of the composite binder also exists at the center of the friction material, so that the shear strength is dramatically improved. This is probably because the coexistence of the phenol resin improved the permeability of the composite binder into the base material.

[0010] The fibrous materials constituting the paper-like substrate include glass fiber, rock wool, potassium titanate fiber, ceramic fiber, silica fiber, silica-alumina fiber, kaolin fiber, bauxite fiber, canonoid fiber, and boron fiber. , Magnesia fiber, inorganic fiber such as metal fiber, linter pulp, wood pulp, synthetic pulp, polyester fiber, polyamide fiber, polyimide fiber, polyvinyl alcohol modified fiber, polyvinyl chloride fiber, polypropylene fiber, polybenzimidazole fiber, One or more organic fibers such as acrylic fibers, carbon fibers, phenol fibers, nylon fibers, and cellulose fibers can be used.

The composite binder formed from at least one of a metal alkoxide and an organic group-substituted metal alkoxide includes silica, alumina, titania, zirconia,
Examples thereof include a metal oxide such as silica-alumina, and an organic functional group composite metal oxide containing an organic group such as a methyl group and a phenyl group. In addition, it is also preferable to include a silicone resin in the composite binder. By including a soft silicone resin, the flexibility is improved, and the coefficient of friction can be further increased by increasing the contact area. The amount of silicone resin mixed is the sum of the composite binder and silicone resin 1
When the amount is 00 parts by weight, the range is preferably 5 to 70 parts by weight.
When the amount of the silicone resin is larger than this, the coefficient of friction becomes smaller, and when the amount is smaller than this, the effect of the addition is hardly exhibited.

It is desirable that the composite binder, which is a component of the friction material of the present invention, contains two or more metal elements including at least a tetravalent metal element. This ensures a higher coefficient of friction and higher wear resistance. Although the reason for this is not clear, other metal elements are introduced into the space mainly composed of one metal element, so that an appropriate twist is generated in the molecule and internal stress occurs. This is considered to increase the skeletal strength of the composite binder.

It is more desirable that the metal elements containing at least a tetravalent metal element have different valences. That is, for example, it is desirable to include a tetravalent metal element and a trivalent metal element, or to include a tetravalent metal element and a divalent metal element. Thereby, the coefficient of friction is further increased, and the wear resistance is further improved.

As the tetravalent metal element, silicon (Si),
Titanium (Ti) is exemplified. Examples of the trivalent metal element include aluminum (Al), gallium (Ga), and iron (Fe). As the divalent metal, magnesium (Mg),
Examples include calcium (Ca) and barium (Ba).
In some cases, a monovalent metal element such as potassium (K) and sodium (Na) may be used.

It is preferable that the trivalent metal element is contained in the range of 0.1 to 5% with respect to the total number of metal elements in the composite binder. Even if the amount of the trivalent metal element is smaller or larger than this range, the wear resistance is reduced. When the content is within this range, the wear resistance is significantly improved.

It is preferable that the divalent metal element is contained in the range of 0.2 to 10% based on the total number of atoms of the metal element in the composite binder. Even if the amount of the trivalent metal element is smaller or larger than this range, the wear resistance is reduced. When the content is within this range, the wear resistance is significantly improved.

The composite binder can be impregnated into a substrate by the following production method. First, in a first step, at least one of a metal alkoxide and an organic group-substituted metal alkoxide is hydrolyzed to prepare a sol solution. Metal alkoxides include silicon (Si), titanium (Ti), aluminum (Al), gallium (Ga), iron (F
e) Alkoxides such as magnesium (Mg), calcium (Ca) and barium (Ba) can be used. Further, as the organic group-substituted metal alkoxide, those in which a part of the alkoxyl group of the above-described metal alkoxide is substituted with an alkyl group can be used.

In the alkoxide used, at least 4
It includes a metal alkoxide of a valent metal element or a metal alkoxide substituted with an organic group, and desirably further includes a metal alkoxide or a metal alkoxide of an organic group substituted with a different kind of metal element. More preferably, it contains a metal alkoxide of at least a tetravalent metal element or an organic group-substituted metal alkoxide, and desirably further contains a metal alkoxide or an organic group-substituted metal alkoxide of a different valence metal element.

The weight ratio of the metal alkoxide to the organic group-substituted metal alkoxide is preferably in the range of metal alkoxide: organic group-substituted metal alkoxide = 3: 7 to 0:10. If the amount of the metal alkoxide exceeds this range, the flexibility of the friction material decreases, and the friction coefficient decreases due to the decrease in the contact area.

The alkoxyl group of the metal alkoxide or the metal alkoxide substituted with an organic group is preferably an alkoxyl group having 1 to 5 carbon atoms. The organic group of the organic group-substituted metal alkoxide preferably has 1 to 10 carbon atoms. By using an organic group-substituted metal alkoxide having an organic group having a carbon number in this range, the shear strength and the like of the obtained friction material are improved.

In order to impregnate the base material with the composite binder, at least one of a metal alkoxide and an organic group-substituted metal alkoxide is hydrolyzed to prepare a sol solution, and the sol solution is formed into a paper-like material made of a fibrous material. A second step of preparing an impregnated base material by impregnating the base material of
The third step of baking can be performed in order.

The first step can be carried out by adding water to an alcohol solution of at least one of a metal alkoxide and an organic group-substituted metal alkoxide, thereby producing a hydroxide sol solution. In the first step, it is desirable to increase the reactivity by adding an acid or an alkali or by heating.

In the first step, it is desirable that the sol solution further contains a silicone resin containing an organic group in a siloxane skeleton. With this configuration, since a part of the composite binder in the friction material from which the soft silicone resin is obtained is formed, the flexibility is improved and the friction coefficient can be further increased.

In the second step, the sol solution prepared in the first step is impregnated into a paper-like substrate made of a fibrous material, and an impregnated substrate in which a sol of a metal hydroxide is impregnated between the fibers is prepared. You. When various friction modifiers are used, they may be mixed in the sol solution prepared in the first step, or may be mixed with a fibrous material to form a paper-like base material. You may make it contain. In some cases, after the sol solution is impregnated into the base material, the sol solution may be sprinkled onto the base material surface and adhered.

The paper-like substrate used in the second step is desirably subjected to a hydroxyl group introduction treatment. Due to the introduced hydroxyl group, the bonding strength between the paper-like base material and the composite binder is greatly improved, and the friction characteristics are further improved.

As the hydroxyl group introduction treatment, for example, there is a method of treating with an acid. As the acid, any of an inorganic acid and an organic acid can be used, but it is preferable to use an organic acid such as acetic acid and oxalic acid. When an organic acid is used, the acid component remaining during the firing in the third step described below is decomposed and disappears, so that the effect on the friction characteristics can be ignored.

The acid treatment can be easily carried out by immersing the paper-like substrate in an acid solution or spraying an acid solution on the paper-like substrate to impregnate the paper-like substrate.

Other methods for introducing a hydroxyl group include a method of treating in an alkaline aqueous solution such as an aqueous solution of sodium hydroxide, a method of treating in boiling water, and a supercritical steam treatment. Since a hydroxyl group can be introduced into the binder, the bonding strength with the composite binder is greatly improved, and the friction characteristics are further improved.

If the paper-like substrate is subjected to a hydroxyl group introduction treatment, the affinity between the metal hydroxide generated in the second step and the paper-like substrate increases, and the hydroxyl group of the metal hydroxide and the paper It is considered that the hydroxyl groups of the base material are oriented so as to be close to each other.

Further, at the time of impregnation, it is preferable that the impregnation is performed with the friction surface facing down. By doing so, although the reason is unknown, Si atoms are increased on the friction surface side, and the friction coefficient is further improved.

Then, by drying and baking the impregnated base material in the third step, the hydroxide sol becomes an oxide gel, and the fibers of the base material are firmly bonded. If a large amount of the organic group-substituted metal alkoxide is used in the first step, the organic group is oriented so as to be close to the organic fiber of the base material in the second step, and more strongly bonded to the organic fiber in the third step. Strength is further improved. The organic group also has the effect of improving flexibility and increasing the coefficient of friction.

Further, if the hydroxyl group introduction treatment has been performed on the paper-like base material in advance in the second step, the metal hydroxide and the fibers are oriented so as to be close to each other in the second step, and the oxide gel is oriented in the third step. Since the fibers and the fibers are firmly bonded, the strength is further improved.

The firing in the third step is desirably performed at 150 to 300 ° C. for 0.5 to 1.0 hour. If the firing temperature is lower than this or the firing time is shorter than this, it is difficult to form an oxide gel, and sufficient strength cannot be obtained. On the other hand, if the firing temperature is higher or the firing time is longer than this, organic substances are decomposed and the frictional characteristics are reduced.

The third step is preferably performed in an atmosphere containing ammonia. Thereby, it is considered that the metal element in the sol is partially nitrided, and the coefficient of friction further increases.
The effect can be obtained if the ammonia is contained at all, but the maximum effect can be obtained if the atmosphere air in the third step contains about 10% by volume.

The third step is desirably performed under supercritical conditions. The supercritical condition is a condition in which the organic matter contained in the base material and the sol is in a state immediately before vaporization, and is a state in which molecular motion is extremely active. The temperature at which the supercritical state is reached by pressurization increases, and molecular motion becomes more active.
High pressure conditions are assumed. In other words, by using high-temperature, high-pressure supercritical conditions, it is possible to improve the reactivity while preventing the decomposition of organic substances, and to stably produce a friction material having a large friction coefficient with less unreacted portions remaining. Becomes possible.

As the phenolic resin, either a resol type or a novolak type can be used, and a phenolic resin binder conventionally used for a friction material can be used as it is. However, in order to maximize the properties of the friction material of the present invention, it is preferable to use a cashew-modified novolak type phenol resin as the phenolic resin. By using this cashew-modified novolak-type phenol resin, a particularly high friction coefficient can be obtained.

The cashew-modified novolak type phenol resin is a total of 100% by weight of the composite binder and the phenol resin.
Preferably, the content is 40 to 80% by weight, and 60 to 70% by weight.
A range of weight% is particularly preferred. 20 phenolic resin
When the amount is less than 80% by weight, the shear strength decreases, and when the amount is more than 80% by weight, the friction coefficient decreases.

The phenolic resin has a melting point of 70 to
It is also preferable to use a powder material at 100 ° C. Use of such a phenolic resin further improves the shear strength.
When this phenolic resin is used, it is preferable that the content be 40 to 80% by weight based on the total 100% by weight of the composite binder and the phenolic resin.

It is also preferable to use a low molecular weight phenolic resin having a viscosity at 25 ° C. of 10 to 50 mPa · s. Even when such a phenolic resin is used, the shear strength is further improved. When using this phenolic resin, the total weight of the composite binder and phenolic resin is 100% by weight.
Preferably, the content is 50 to 80% by weight.

It is also preferable to use a phenolic resin having a polar group having a high affinity for a paper-like substrate made of a fibrous material. When such a phenolic resin is used, the adhesiveness of the binder to the paper-like base material is improved, so that the μ-V gradient is improved. The phenolic resin having a polar group having a high affinity for a paper-like substrate includes a hydrophobic group-modified phenol resin, an epoxy-modified phenol resin, an alkylbenzene-modified phenol resin,
A bismaleimide-modified phenol resin is exemplified.
The phenolic resin is preferably present in an amount of 40 to 80% by weight based on 100% by weight of the total of the composite binder and the phenolic resin.

The μ-V gradient means a slip velocity of 0.05 m.
The ratio of the coefficient of friction at a sliding velocity of 0.5 m / s to the coefficient of friction at 0.5 m / s. A μ-V gradient of 1 indicates a flat friction characteristic, and a μ-V gradient greater than 1 indicates a positive gradient friction characteristic. If it is less than the value, a negative gradient friction characteristic is exhibited. The dynamic friction coefficient is desirably higher than the static friction coefficient, and the higher the slip speed, the higher the friction coefficient. Therefore, the friction material of the present invention desirably has a μ-V slope of 1 or more.

When a base material is impregnated with a phenolic resin and a sol solution formed from at least one of a metal alkoxide and an organic group-substituted metal alkoxide as a composite binder source, one may be impregnated first, or both may be impregnated. It can also be impregnated by mixing. However, it is preferable to impregnate a phenolic resin first, and then impregnate a sol solution formed from at least one of a metal alkoxide and an organic group-substituted metal alkoxide. Thereby, a friction material with particularly improved friction coefficient and shear strength can be obtained. In the examples described later, the order of impregnating the phenolic resin first and then impregnating the sol solution is normal.

The friction material of the present invention includes, for example, barium sulfate, calcium carbonate, magnesium carbonate, silicon carbide,
Boron carbide, titanium carbide, silicon nitride, boron nitride, alumina, silica, zirconia, cashew dust, rubber dust, diatomaceous earth, talc, kaolin, magnesium oxide,
Molybdenum disulfide, nitrile rubber, acrylonitrile
Various kinds of friction modifiers and fillers such as butadiene rubber, styrene butadiene rubber, silicon rubber, and fluororubber can be used by mixing one or more of them in appropriate amounts.

The composition ratio of each component is preferably such that the total amount of the composite binder and the phenolic resin is in the range of 10 to 70% by volume with respect to 100% by volume of the total amount of the fibrous material and the friction modifier. . If the total amount of the composite binder and the phenolic resin is less than this, the bonding strength of the fibers in the paper-like base material is reduced, and the durability is reduced. If the total amount is more than this, the friction characteristics are reduced.

[0045]

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

Example 1 (1) Cashew-modified novolak type phenol resin (“PR
-12687 "(manufactured by Sumitomo Durez Co., Ltd.) (referred to as a standard product) was dissolved in ethanol and impregnated into a paper-like substrate made of linter pulp. This was dried at 180 ° C. for 10 minutes, and the phenol resin was cured to some extent to obtain a primary impregnated base material. (2) Next, 27.6 g of ethanol and 20.8 g of methyltriethoxysilane (CH ₃ Si (OC ₂ H ₅ ) ₃ ) were weighed in a glass container,
Stirred for 10 minutes. Thereafter, the solution was stirred for 0.05
A 20 g aqueous solution of N hydrochloric acid was added dropwise, and the mixture was further stirred for 24 hours to prepare a sol solution.

Then, the sol solution was impregnated into the primary impregnated substrate to obtain a secondary impregnated substrate. At this time, since the phenol resin is partially cured in the primary impregnated base material, elution into the sol solution is prevented. (3) The obtained secondary impregnated substrate is dried at room temperature for 1 hour, molded at 180 ° C for 10 minutes in the air using a prescribed molding machine, and then adhered to a plate and heated at 180 ° C for 30 minutes. The wet friction material of Example 1 was prepared.

In this friction material, the impregnation amount of the phenol resin is 30% by weight, and the impregnation amount of the composite binder formed from the sol solution is 23% by weight.

Example 2 The phenol resin impregnation amount was 13
A friction material was prepared in the same manner as in Example 1 except that the amount of the composite binder formed from the sol solution was 35% by weight.

Example 3 An ethanol solution of a phenol resin and a sol solution were mixed and impregnated into a substrate, molded at 180 ° C. for 10 minutes in the air using a predetermined molding machine, and then adhered to a plate. A friction material was prepared in the same manner as in Example 1 except that the heating was performed for 30 minutes.

In this friction material, the impregnation amount of the phenol resin is 17% by weight, and the impregnation amount of the composite binder formed from the sol solution is 17% by weight.

Example 4 First, a sol solution was impregnated.
A friction material was prepared in the same manner as in Example 1, except that it was impregnated with an ethanol solution of a phenol resin after drying at 80 ° C. for 10 minutes.

In this friction material, the impregnation amount of the phenol resin is 7% by weight, and the impregnation amount of the composite binder formed from the sol solution is 38% by weight.

(Example 5) The impregnation amount of the phenol resin was 28
A friction material was prepared in the same manner as in Example 1, except that the amount of the composite binder formed from the sol solution was 20% by weight.

Example 6 Instead of the cashew-modified novolak type phenol resin, a powdery phenol resin having a melting point of 79 ° C. (“PR-11078” manufactured by Sumitomo Durez Co., Ltd.) dissolved in acetone was used. 24% by weight of resin impregnation
And the impregnation amount of the composite binder formed from the sol solution is
A friction material was prepared in the same manner as in Example 1 except that the amount was 27% by weight.

(Example 7) Instead of the cashew-modified novolak type phenol resin, the viscosity at 25 ° C was 41 mPa ·
s high molecular weight straight resol type phenolic resin ("PR-54313" manufactured by Sumitomo Durez Co., Ltd.), the impregnation amount of the phenolic resin is 28% by weight, and the impregnation amount of the composite binder formed from the sol solution is 25% by weight. %, And a friction material was prepared in the same manner as in Example 1.

(Example 8) A low molecular weight straight resole type phenol resin ("PR-54562") was used as the phenol resin.
Friction material in the same manner as in Example 1 except that the impregnation amount of the phenol resin was 24% by weight and the impregnation amount of the composite binder formed from the sol solution was 28% by weight using Sumitomo Durez Co., Ltd. Was prepared.

(Comparative Example 1) A cashew-modified novolak type phenol resin alone was impregnated without using a sol solution, molded at 180 ° C. for 10 minutes in the air using a predetermined molding machine, and then adhered to a plate. A friction material was prepared in the same manner as in Example 1 except that heating was performed for 30 minutes.

In this friction material, the phenol resin impregnation amount is 22% by weight.

(Comparative Example 2) A cashew-modified novolak type phenol resin was not used, and only a sol solution was impregnated, molded at 180 ° C for 10 minutes in the air using a predetermined molding machine, and then adhered to a plate and heated at 180 ° C. A friction material was prepared in the same manner as in Example 1 except that heating was performed for 30 minutes.

In this friction material, the impregnation amount of the composite binder formed from the sol solution is 40% by weight.

(Comparative Example 3) A cashew-modified novolak-type phenol resin alone was impregnated without using a sol solution, molded at 180 ° C for 10 minutes in the air using a predetermined molding machine, and then adhered to a plate. A friction material was prepared in the same manner as in Example 1 except that heating was performed for 30 minutes.

In this friction material, the impregnation amount of the phenol resin is 45% by weight.

(Test / Evaluation) The friction coefficient of each of the above wet friction materials in oil at 120 ° C. was measured. A ferrous material is used as the mating material, with a surface pressure of 10 kg / cm2 and 0.0
The coefficient of friction at 1 m / sec was measured. The shear strength was measured by a tensile tester. Further SAE #
Under a condition shown in Table 1, a slip speed of 0.
The friction coefficient at 05 m / s and the friction coefficient at a sliding speed of 0.5 m / s were measured, and the μ-V slope was determined. Table 2 shows the results.

[0065]

[Table 1]

[0066]

[Table 2]

The cross sections of the friction materials of Example 1 and Comparative Example 2 were observed by SEM, and the results are shown in FIGS. 1 and 2, respectively. In the friction material of Comparative Example 2, the surface layer
Si (white part in the figure) exists in high concentration, and almost no Si is found in the center. On the other hand, in the friction material of Example 1, it was recognized that Si was slightly present in the surface layer portion but was also present in the central portion. The presence of Si indicates the presence of the composite binder, and in the portion where Si is present, the fibers are also entangled by the composite binder. Therefore, the friction material of Example 1 is considered to have improved shear strength as compared with the friction material of Comparative Example 2. Note that the reason why the composite binder permeated to the center in Example 1 is considered to be that the compatibility of the composite binder with the base material was improved by the phenolic resin.

Therefore, when the results shown in Table 1 are examined, the friction material of each example shows a larger friction coefficient than the friction materials of Comparative Examples 1 and 3. Since the friction material of Comparative Example 2 also shows a large friction coefficient, this is an effect using the composite binder.

Further, the friction material of each example has a remarkably improved shear strength as compared with the friction material of Comparative Example 2. From the comparison between Example 5 and Example 2 and the comparison between Comparative Example 3 and Example 3, the effect of the combined use of the composite binder and the phenol resin was improved even if the influence of the total resin ratio was subtracted. It is clear that

From the comparison between Example 2 and Examples 3 and 4, it was found that it is preferable to impregnate the phenolic resin first and then impregnate the sol solution. It can be seen that the same effect is obtained even when the type of the resin is changed.

Further, the friction material of the eighth embodiment has a μ-V gradient of 1.00, which is a positive gradient, and has a performance protruding from other friction materials. This is clearly the effect of using the composite binder and the low molecular weight straight resole type phenol resin in combination.

[0072]

According to the friction material of the present invention, a large friction coefficient and a high shear strength can be ensured by using an organic paper-like base material. This eliminates the necessity of stacking a large number of sheets as in the related art, and avoids a problem that the wet clutch structure becomes complicated and large-scale and energy loss increases. Also, the cost is reduced.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing a particle structure of a friction material of Example 1.

FIG. 2 is an electron micrograph showing a particle structure of a friction material of Comparative Example 2.

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Claims (10)

[Claims] 1. A paper-like substrate made of a fibrous material, a composite binder formed from at least one of a metal alkoxide and an organic group-substituted metal alkoxide and impregnated in the substrate, and phenol impregnated in the substrate A friction material characterized by comprising a base resin. 2. The friction material according to claim 1, wherein the phenolic resin is a cashew-modified novolak-type phenolic resin. 3. The method according to claim 1, wherein the substrate is impregnated with the phenolic resin, and then impregnated with a sol solution formed from at least one of a metal alkoxide and an organic group-substituted metal alkoxide. 3. The friction material according to 2. 4. The phenolic resin contains 40 to 40% by weight of the total of the composite binder and the phenolic resin.
The friction material according to claim 2, wherein the friction material is contained in an amount of 80% by weight. 5. The phenolic resin has a melting point of 70 to 100.
The friction material according to claim 1, wherein the friction material is a powder material at a temperature of ℃. 6. The phenolic resin contains 40 to 40% by weight of the total of the composite binder and the phenolic resin.
The friction material according to claim 5, wherein the friction material is contained by 80% by weight. 7. The phenolic resin has a viscosity at 25 ° C. of 10 to 50 mPa · s.
The friction material according to the above. 8. The phenolic resin contains 50 to 50% by weight in total of the composite binder and the phenolic resin.
The friction material according to claim 7, wherein the friction material is contained by 80% by weight. 9. The friction material according to claim 1, wherein the phenolic resin has a polar group having a high affinity for the base material. 10. The phenolic resin according to claim 9, wherein the phenolic resin is at least one selected from a hydrophobic group-modified phenolic resin, an epoxy-modified phenolic resin, an alkylbenzene-modified phenolic resin, and a bismaleimide-modified phenolic resin. Friction material.