JPH09119465A - Wet frictoin member and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a judder phenomenon by smoothening and uniforming slippage between a wet frictional member and a counterpart member. SOLUTION: Combined synthetic resin liquid in which hard carbon powder or fiber is mixed/dispersed, is applied to a paper making body formed by manufacturing a mixed material comprising of base material fiber and a filler such as a friction adjusting agent so as to impregnate a resin therewith, and at the same time, the carbon powder or fiber is implanted on a surface layer, and next, the resin is cured by being heated. Hereby, paper type wet friction members 1 can be obtained, which are made to serve as a main body, and equipped with carbon layers consisting of the hard carbon powder or fiber which is combined and retained by a combined resin on the sliding surfaces of the friction materials 1, so that slippage between the friction members 1 and counterpart members 4 is smoothened and uniformed by the self- lubricating action of the carbon, therefore, a judder phenomenon is suppressed. Also, the carbon powder or fiber is mixed and dispersed to the combined resin liquid impregnated in the paper forming body so that the another independent process for forming the carbon layers is no more required, therefore, wet friction members can be easily manufactured in the same manufacturing process as the conventional case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet friction material used in an automatic transmission of an automobile or the like, that is, a wet friction material used in a friction engagement device such as a clutch or a brake used in a state of being immersed in lubricating oil, and The present invention relates to a manufacturing method thereof.

[0002]

2. Description of the Related Art In an automatic transmission of an automobile, a friction plate made of a plurality of disc plates each having a wet friction material adhered to the surface of a ring plate-shaped metal base plate (core metal) and a friction partner made of a ring plate-shaped metal plate. In the ATF (Automatic Transmission Fluid) used as lubricating oil, a multi-plate clutch in which a plurality of separate plates as materials are alternately arranged is incorporated, and these friction materials and the mating material are pressed against each other, By opening it again,
The drive force is transmitted or cut off. In recent years, due to the development of such automatic transmission control methods,
A slip control method has been developed in which a driving force is transmitted while generating a differential rotation between the wet friction material and the mating material. Further, according to this slip control method, the friction material and the mating material transmit the driving force while sliding, so that a state similar to that of the half clutch occurs, and the driving force can be smoothly transmitted.

It should be noted that similar multi-disc brakes or band brakes are commonly incorporated into automatic transmissions to secure and release reaction elements. In the case of this band brake, the wet friction material is glued to the brake band,
It frictionally engages with a brake drum as a mating member to brake its rotation.

Conventionally, as a wet friction material used for a friction engagement device used in such an oil, a friction material such as a sintered alloy type or a carbon composite type has been known. Paper-based wet friction materials, which are also called "friction materials", are common. This wet friction material is a paper body obtained by paper-making a base material fiber such as pulp or aramid fiber and a friction modifier such as cashew dust or a filler such as a constitutional filler such as diatomaceous earth. It is formed by applying a binder resin solution, impregnating it, and then heat-curing it.It is not only lightweight and inexpensive, but also highly oil-absorptive because its material is porous and relatively rich in elasticity. It has features such as relatively excellent heat resistance and wear resistance.

Regarding such a paper-based wet friction material, for example, Japanese Patent Laid-Open No. 1-288639 (improvement of binding resin) and Japanese Patent Publication No. 2-61661 (improvement of cashew dust which is a friction modifier) are known. )It is described in.

As for this type of wet friction material, there is also known a wet friction material having a carbon layer formed on its sliding surface in order to improve its friction characteristics.

For example, in Japanese Unexamined Patent Publication No. 61-85443, a non-woven fabric or paper-like sheet (paper making body) is impregnated with a binder resin solution made of a heat-resistant (and low-elasticity) thermosetting resin and heat-cured. The surface of the wet friction material body obtained by applying the same type of binding resin liquid mixed with a fine powder of a solid lubricant, then heat-cured wet friction material is disclosed, as the solid lubricant, Carbon powders such as graphite and coke are listed as well as molybdenum disulfide and tungsten disulfide.

US Pat. No. 4,639,392 discloses
For example, a normal carrier sheet such as a friction sheet obtained by impregnating a papermaking body made of cellulose fiber and a filler such as diatomaceous earth with a phenol resin and curing the paper (wet friction material for paper)
A mixture of carbon particles made of petroleum coke and phenol resin powder or phenol resin liquid is evenly applied to the surface of a solid film adhesive, and then compression molding or heat curing is performed to obtain a wet friction material (friction facing). Layers) are disclosed.

Further, in US Pat. No. 5,083,650,
A heat-resistant paper (papermaking body) obtained by making aramid fibers or the like is coated with a binder resin solution composed of a thermosetting resin such as a phenol resin in a viscous state to coat its surface and at least partially impregnate it. , Then, a granular carbon particle made of coke or the like is adhered to the surface thereof to partially embed it, and after at least partially heat curing this,
Further, a wet friction material is disclosed in which the same type of thermosetting resin liquid is applied to the surface (however, so as not to cover the carbon particles) and heat-cured again. (Note that
Carbon filler particles are preferably added to the thermosetting resin liquid. )

[0010]

As described above, as a wet friction material in an automatic transmission of an automobile or the like, a papermaking obtained by paper-making a mixed material of a base fiber and a filler such as a friction modifier. A paper-based wet friction material obtained by coating and impregnating a body with a binder resin liquid, and then heat-curing it, that is, a papermaking body of base fibers filled with a filler such as a friction modifier dispersed therein. Wet friction materials that are entirely impregnated and bound by a hardened binder resin are commonly used.

However, since this paper-based wet friction material is relatively elastic due to its porous material, it is inherently excellent in contactability (compatibility, followability) with the mating material, but On the contrary, due to the flexibility, the finishing treatment for smoothing the surface is relatively difficult, so the hitting performance is not always sufficient. And tended to come into contact with each other. And this insufficient hitability,
That is, the deviation of the contact causes non-uniformity of slippage (torque fluctuation) with the mating material, especially during slip control of the automatic transmission described above, which causes a judder phenomenon, vibration, and squeal. There was a tendency for problems such as Therefore, it has been demanded that this type of wet friction material used particularly in the slip control method can obtain smooth and uniform sliding with the mating material and suppress the judder phenomenon.

By the way, the aforementioned Japanese Patent Laid-Open No. 61-85443.
According to the technology disclosed in Japanese Patent Publication No. 1993 or US patent specification, that is, a paper-based wet friction material in which a carbon layer is formed on a sliding surface, the self-lubricating effect of the carbon prevents slippage with a mating material. It is possible to make it smoother and uniform. Therefore, the judder phenomenon can also be suppressed. However, each of these techniques specifically requires a separate process for forming the carbon layer, which is independent from the formation of the wet friction material body, and therefore the manufacturing process becomes complicated and It took time to manufacture.

Therefore, the present invention provides a wet friction material and a method for manufacturing the wet friction material, in which slippage with a mating material can be made smooth and uniform, the judder phenomenon can be suppressed, and which can be easily manufactured. The challenge is to provide.

[0014]

Means for Solving the Problems In the general process of manufacturing a paper-based wet friction material in which a papermaking body is coated with a binder resin solution, impregnated with the binder resin solution, and then heat-cured, the binder resin solution is previously added to the binder resin solution. By mixing and dispersing carbon powder or fibers, the binder resin is impregnated into the paper making body, while the paper making body acts like a filter material and the carbon powder or fibers is imbedded on the surface layer. It is noted that it is possible to easily obtain a wet friction material having a carbon layer on a sliding surface by heating and then curing the binder resin by heating, and then manufacturing the wet friction material. It was confirmed that the obtained wet friction material can be smoothed and made uniform with the counterpart material by the carbon layer, and the judder phenomenon can be suppressed.

That is, in the wet friction material according to the present invention, a hard carbon powder or fiber is mixed and dispersed in a paper body obtained by making a mixed material of a base fiber and a filler such as a friction modifier. A method in which the binder resin liquid is applied, the binder resin is impregnated into the papermaking body, and at the same time the carbon powder or fibers are implanted on the surface layer of the papermaking body, and then the binder resin is cured by heating. Is.

In the method for producing a wet friction material according to the present invention, a hard carbon powder or fiber is added to a paper body obtained by making a mixed material of a base fiber and a filler such as a friction modifier. Is coated and mixed with the binder resin solution to impregnate the papermaking body with the binder resin, and at the same time, the carbon powder or fiber is implanted on the surface layer of the papermaking body, and then heated to cure the binder resin. It consists of things.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

In the present invention, the carbon powder or fiber forming the carbon layer is not a soft material such as graphite or coke but is a hard material that is not substantially graphitized, preferably in Mohs hardness. Those of 6 to 8 are used. Then, such hard carbon powder is, for example, carbonized and baked thermosetting resin such as phenol resin or petroleum-coal pitch under a non-oxidizing atmosphere,
Further, the carbonized fired body can be obtained by finely pulverizing the carbonized fired body to a predetermined particle size. In this case, the firing temperature is 600 ° C. to 20 ° C.
00 ° C is preferable, and 800 to 14 which is the hardest
00 ° C is more preferred. If the temperature is lower than 600 ° C., the organic component tends to remain, and the hardness is low and the elastic modulus is low, which is not preferable. On the other hand, if the temperature is 2000 ° C. or higher, graphitization of carbon, that is, crystallization proceeds, so that both hardness and elastic modulus decrease, which is not preferable. The particle size of the hard carbon powder is generally 0.1 to 50 μm, preferably 5 to 15 μm, and the carbon purity is preferably 90% or more. Further, similar hard carbon fibers can be obtained, for example, by cutting carbon fibers synthesized from petroleum pitch into powdery short fibers, and the average fiber length thereof is preferably about 0.1 mm.

The other materials for forming the wet friction material in the present invention are the same as conventional materials. That is, examples of the base fiber include pulp or organic fiber such as aramid fiber and novoloid fiber, glass fiber, rock wool, silicate fiber, inorganic fiber such as alumina fiber, steel fiber, metal fiber such as stainless steel fiber, and the like. be able to. And, each of these base fibers alone,
Alternatively, two or more kinds may be appropriately combined and used.

Further, as a filler which is added to modify and improve the characteristics of the obtained wet friction material, and which is dispersed and filled in the matrix of the base fiber and held, friction such as cashew dust is used. Examples include regulators and body-filling agents such as diatomaceous earth, and these can be appropriately blended in the same manner as in the past.

Further, as the binder resin, a thermosetting resin is generally used, and examples thereof include a phenol resin, an epoxy resin, a melamine resin, a polyimide resin and a polyester resin. However, modified or non-modified phenolic resins can be preferably used among these, in view of excellent binding properties, heat resistance, etc., and easy handling. Further, since this binder resin penetrates into the papermaking body and is impregnated into it, it is used in the form of a liquid having an appropriate viscosity as in the past, and is used as a liquid resin as it is, or it is dissolved in an appropriate solvent and diluted. It can be used as a varnish.

In the present invention, the wet friction material using such a material as a raw material can be manufactured in the substantially same process as the conventional process. Specifically, papermaking of a mixed material of a base fiber and a filler such as a friction modifier, that is, the formation of a paper body, the mixed material is dispersed in water to prepare a slurry, and this slurry is This can be carried out by filtering with a papermaking machine to form a wet papermaking body consisting of the filter cake of the mixed material, and then squeezing and drying. Next, in the present invention, in the step of applying the binder resin liquid, the hard carbon powder or fiber is mixed with the binder resin liquid and uniformly dispersed, and this is applied to the surface of the obtained papermaking body. Apply. However, this coating itself can be performed by means such as dipping, spraying, or a coating roll as in the conventional case. Next, the paper body impregnated with the binder resin and the carbon powder or fibers deposited on the surface layer portion in this coating step is appropriately dried and then heated to the curing temperature of the binder resin to cure it.

The wet friction material produced in this manner is used for a wet friction engagement device in an automatic transmission or the like as a wet friction plate (disk plate) or the like by being subjected to appropriate finishing processing and adhering to an appropriate core metal. To be done.

(Operation) In the present invention, a hard carbon powder or fiber is mixed and dispersed in a paper body obtained by making a mixed material of a base fiber of the paper body and a filler such as a friction modifier. Since the binding resin liquid that has been applied is applied,
The binding resin permeates and impregnates the papermaking body, while the carbon powder or fiber is retained on the surface layer portion of the papermaking body because the papermaking body is like a filter material (filter paper). Therefore, by heating this and then curing the binder resin, the paper body composed of the base fibers and the filler is bound by the impregnated binder resin, and at the same time the wet friction material main body is formed, its surface layer. The carbon powder or fibers that have landed on the part are firmly bound and held by the binding resin. That is,
A wet friction material having a paper-based wet friction material as a main body and a carbon layer made of hard carbon powder or fibers formed on a sliding surface thereof can be easily manufactured by a substantially single step. .

According to the obtained wet friction material, the self-lubricating property of the carbon makes the sliding with the mating material more smooth and uniform. Therefore, torque fluctuation can be reduced and the judder phenomenon can be suppressed. In this case, since the carbon is made of hard carbon, good friction characteristics and wear resistance can be maintained. Further, the carbon powder or fiber is substantially contained only in the surface layer portion of the papermaking body, that is, the sliding surface portion of the friction material to form the carbon layer, and the main body portion of the friction material is different from the conventional one. Since they are made of the same material, heat resistance, peeling resistance, etc. do not deteriorate, and general performance equivalent to the conventional one is secured.

[0026]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

<First Embodiment> First, as a first embodiment,
The wet friction material using the powder as the hard carbon forming the carbon layer and its manufacturing method will be described.

The wet friction material of the first embodiment was manufactured as follows.

First, 50% by weight of pulp as a base fiber
And 10% by weight of aramid fiber, 10% by weight of cashew dust (friction modifier) as a filler, and 30% by weight of diatomaceous earth (extensive filler) are made into paper, and a papermaking body having the blended composition is produced. Formed. On the other hand, separately, a phenol resin cured product is carbonized and baked at 800 ° C. in a non-oxidizing atmosphere, and the carbonized and baked product thus obtained is pulverized to obtain a hard carbon powder having an average particle size of 10 μm. Manufactured. The specific gravity of this carbon is 1.
It was 4 to 1.6, and the Mohs hardness was about 6.5.

Then, the hard carbon powder was mixed with a phenol resin varnish as a binder resin at a ratio of 5% by weight to uniformly disperse the powder, which was then applied to the above-mentioned papermaking body by dipping, The resin component was impregnated. Then
This was taken out (at this time, the hard carbon powder was uniformly deposited on the surface layer of the papermaking body and had been implanted), and after naturally drying, it was treated in a furnace at 200 ° C for 10 minutes. Then, the phenol resin was cured by heating. Then, the heat-cured body was molded by a hot press at 200 ° C., and further machined to produce a wet friction material. As a result, a hard carbon powder was firmly landed on the sliding surface portion, and a wet friction material having a carbon layer was obtained.

The wet friction material thus produced was subjected to slip evaluation (continuous sliding friction evaluation test). Specifically, this slip evaluation was performed as shown in FIG.

FIG. 1 is a schematic diagram showing a slip evaluation method for the wet friction material.

In this evaluation test, the wet friction material 1 produced by the above method was adhered to both sides of the ring-plate-shaped core metal 2 to prepare a test piece. Then, the iron plate 4 which is a mating member assembled in the tester case 3 so as not to rotate.
Then, it was pressed through the piston 5 with a load of a surface pressure of 20 kg / cm ² . Next, the specimen was rotated by the hub 6 at a rotational speed of 10 rpm assuming a differential rotation speed, and the amount of non-uniform slip generated at this time was detected as a torque amplitude (amount of torque fluctuation), and was evaluated. In addition, these operations are ATF
This was carried out in a state of being immersed in the glass.

As a result, the torque amplitude was 2 kg · m.

Next, for comparison, a wet friction material having no carbon layer made of the above-mentioned hard carbon powder was prepared as a comparative example, and slip evaluation was performed by the same method as in the example. The wet friction material of this comparative example was made of the same material as the above-mentioned example except that the carbon powder was not mixed with the phenol resin varnish, and was made by the same manufacturing process.

As a result, the torque amplitude of the wet friction material of this comparative example was 15 kg · m.

From the results of this slip evaluation test, the wet friction material of this example, in which the carbon layer made of hard carbon powder was formed on the sliding surface, was the wet friction material of the comparative example which did not have this. The torque amplitude is significantly smaller than
Therefore, it can be seen that the amount of non-uniform slip is small.

As described above, the wet friction material of the present embodiment was prepared by paper-making a mixed material of pulp and aramid fibers, which are base fibers, and cashew dust and diatomaceous earth, which are fillers. A binder resin solution consisting of a phenol resin in which a hard carbon powder obtained by carbonizing and firing a cured resin is finely pulverized is applied, and the binder resin is impregnated into the papermaking machine and at the same time the carbon powder is removed. It is produced by landing on the surface layer of the papermaking body and then heating to cure the binder resin.

Therefore, by being manufactured in this manner, the papermaking body made of the mixed material of the base fiber and the filler is bound by the impregnated binding resin, and at the same time the wet friction material body is formed. The hard carbon powder deposited on the surface layer is also firmly bound and held by the binding resin. That is, a wet friction material having a paper-based wet friction material as a main body and having a carbon layer made of hard carbon powder on the sliding surface thereof is obtained. Therefore, according to the wet friction material, the self-lubricating action of the carbon makes the slip between the mating material and the other material smooth, and the transmitted torque becomes uniform. As a result, the judder phenomenon is suppressed, and vibration and squeal can be prevented. Further, as the carbon, a hard one (Mohs hardness 6.5) obtained by carbonizing and firing a cured phenol resin at 800 ° C. is used, so that good friction characteristics and wear resistance are secured. be able to.

In order to produce such a wet friction material having a carbon layer on the sliding surface, the carbon powder is previously mixed and dispersed in the binder resin liquid to be applied and impregnated on the papermaking body. Therefore, without adding a new step for forming a carbon layer to the conventional general wet friction material manufacturing method, since it is performed by the same steps as the conventional general wet friction material manufacturing method, There is an effect that the above friction material can be manufactured easily and easily.

By the way, similarly to this, in order to suppress the judder phenomenon and improve the slip performance, it is necessary to preliminarily mix a large amount of the carbon powder in the paper body, that is,
It is also conceivable that a larger amount of carbon powder is mixed with a mixed material of the base fiber and a filler such as a friction modifier, and the resulting mixture is combined to form a paper body. However, in such a wet friction material containing a large amount of carbon powder, not only the paper strength is lowered, but also the original performance as a paper-based wet friction material may be significantly changed. On the other hand, in the wet friction material of the present embodiment, the carbon powder is contained substantially only in the surface layer portion of the papermaking body, the carbon layer is formed substantially only in the sliding surface portion, and the wet friction material is used. Since the main body of the material is made of the same material as before, there are no such problems, and heat resistance (oil absorption), peeling resistance, etc. do not deteriorate, and good general performance equivalent to the conventional one can be secured. .

When carbon powder is preliminarily blended in the papermaking body, sufficient slip performance cannot be obtained if the blending ratio is small. Specifically, 45% by weight of pulp, 10% by weight of aramid fiber, 10% by weight of cashew dust, and 25% by weight of diatomaceous earth are further combined with 10% by weight of the hard carbon powder used in the present example to make paper. Then, to form a paper body in which the carbon powder is uniformly dispersed throughout, by applying only a phenol resin varnish to the paper body to impregnate it, and then heat-curing the wet friction material of another comparative example. It was made. When the above slip evaluation was performed on this, the torque amplitude was 8 kg · m. This torque amplitude is less than 15 kg · m of the above comparative example which does not use carbon powder at all, but it is 2 kg · m of this embodiment.
It is not enough compared with.

<Second Embodiment> Next, as a second embodiment,
A wet friction material using the fibers as the hard carbon forming the carbon layer will be described.

The wet friction material of the second embodiment was manufactured as follows.

Using the same papermaking body and phenol resin varnish as in the first embodiment, carbon fibers of high hardness (Mohs hardness of about 7) and high elasticity synthesized from petroleum pitch were used, and an average fiber length of 0. Prepare powdery carbon fiber cut into 1 mm, mix and disperse the carbon fiber in the phenol resin varnish so as to be 5% by weight, and then apply the phenol resin varnish to the paper body in the same manner as in the first embodiment. Apply
The wet friction material of the second example was obtained by impregnating the resin with carbon fibers and immobilizing the carbon fibers on the surface layer, followed by air-drying, thermosetting, thermoforming and machining. The obtained wet friction material is bound by the impregnated phenolic resin to the papermaking body to form the main body portion, while the carbon fibers deposited on the surface layer portion are also bonded and held by the phenolic resin. The carbon layer was formed on the sliding surface portion.

Then, with respect to this wet friction material, slip evaluation was carried out in the same manner as in the first embodiment. As a result, the torque amplitude was 3 kg · m.

Next, as a comparative example, a wet friction material was prepared using the same powdery glass fiber instead of carbon fiber, and the slip evaluation was carried out in the same manner. The wet friction material of this comparative example was manufactured under the same conditions and manufacturing steps as in this example except that glass fiber was used instead of carbon fiber.

The wet friction material of the comparative example produced in this way and having the glass fiber layer on the sliding surface portion had a torque amplitude of 9 kg · m.

From these results, the wet friction material of this example having a carbon layer made of hard carbon fibers on the sliding surface had a significantly smaller torque amplitude than the comparative example, and therefore the non-uniform sliding amount was large. It turns out that there are few.

As described above, the wet friction material of this embodiment is a mixture of the base fiber pulp and aramid fiber and the fillers cashew dust (friction modifier) and diatomaceous earth (extensive filler). The paper body obtained by papermaking is coated with a binder resin solution composed of a phenol resin in which powdery hard carbon fibers are mixed and dispersed, and the paper body is impregnated with the resin, and at the same time, carbon powder is applied to the surface layer portion thereof. It is produced by flooring and then heating to cure the resin.

Therefore, according to this wet friction material, since the sliding surface portion is provided with the carbon layer made of hard carbon fiber, the carbon layer smoothes the sliding between the mating material and the transmission torque. It is possible to obtain the same effects as in the first embodiment, such as uniforming and suppressing the judder phenomenon. Further, the wet friction material having the carbon layer can be prepared by mixing and dispersing carbon fibers in advance in the binder resin liquid to be applied and impregnated on the papermaking body,
Since it is manufactured by the same process as the manufacturing of a conventional general wet friction material, it has an effect that it can be manufactured easily and easily.

The wet friction material of the present invention has been described mainly in connection with its use in the wet friction engagement device in the automatic transmission of an automobile. For use in various applications, especially for use with slip control methods, as well as other wet friction engagement devices,
That is, it can be similarly advantageously used as a wet friction material of a friction engagement device such as a clutch or a brake used in oil. Also, regarding the type and composition ratio of the filler such as the fiber base material and the friction modifier, the type of the binding resin, etc.,
The present invention is not limited to the above embodiment, but can be variously changed according to desired characteristics and the like.

[0053]

As described above, the wet friction material according to the present invention has a paper body made of a mixed material of a base fiber and a filler such as a friction modifier, and a hard carbon powder or The binder resin liquid in which the fibers are mixed and dispersed is applied, and the binder resin is impregnated into the papermaking machine, and at the same time, the carbon powder or fibers are implanted on the surface layer of the papermaking machine, and then heated to cure the binder resin. It is something that can be done.

Further, in the method for producing a wet friction material according to the present invention, a hard carbon powder or fiber is added to a paper body obtained by making a mixed material of a base fiber and a filler such as a friction modifier. Applying the mixed and dispersed binder resin solution, impregnating the binder with the binder resin, and at the same time implanting the carbon powder or fibers on the surface layer of the binder, then heating to cure the binder resin. It consists of

Therefore, by being manufactured in this way, the paper body made of the mixed material of the base fiber and the filler is bound with the binder resin which is impregnated and hardened to form the wet friction material body. On the other hand, the hard carbon powder or fibers deposited on the surface layer are also firmly bonded and held by the hardened binding resin to form a carbon layer. That is, a wet friction material having a paper-based wet friction material as a main body and having a carbon layer made of hard carbon powder or fibers on the sliding surface portion is formed. Therefore, according to this wet friction material, the self-lubricating property of the carbon makes it possible to make the slip between the other material smoother and more uniform, thereby suppressing the judder phenomenon. Vibration and squeal can be prevented from occurring. Further, since the carbon is made of hard carbon, good friction characteristics and wear resistance can be maintained. Furthermore, since the carbon layer is formed only on the sliding surface of the wet friction material and the main body is formed of the same material as before, there is no adverse effect on heat resistance, peeling resistance, etc. It is possible to maintain the excellent characteristics of the system wet friction material as it is.

Further, the production of the wet friction material having the carbon layer is carried out only by using as the binding resin liquid for coating and impregnating the papermaking body, carbon powder or fibers which have been previously mixed and dispersed, Since it is performed by the same process as the conventional manufacturing process of a general wet friction material without adding an independent process for forming a carbon layer, the conventional wet friction material manufacturing process can be performed in spite of having such a carbon layer. There is an effect that it can be easily manufactured by a simple process.

That is, according to the wet friction material of the present invention and the method for manufacturing the wet friction material, the sliding between the mating material can be made smooth and uniform, and the judder phenomenon can be suppressed.
There is an effect that it can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for evaluating slip of a wet friction material.

[Explanation of symbols] 1 wet friction material 2 core metal 4 iron plate (counterpart material)

Claims (2)

[Claims] 1. A binder resin liquid in which hard carbon powder or fibers are mixed and dispersed is applied to a paper body obtained by forming a mixed material of a base fiber and a filler such as a friction modifier, Wet friction characterized by impregnating the papermaking body with a binder resin and at the same time impregnating the carbon powder or fibers on the surface layer of the papermaking body, and then heating to cure the binder resin. Material. 2. A binder resin solution in which hard carbon powder or fibers are mixed and dispersed is applied to a paper body obtained by forming a mixed material of a base fiber and a filler such as a friction modifier, At the same time as impregnating the papermaking body with a binder resin, depositing the carbon powder or fibers on the surface layer portion of the papermaking body, and then heating to cure the binder resin. Production method.