JPH0972363A - Heat-resisting wet-type friction material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively manufacture a heat-resisting wet-type friction material which is excellent both in frictional performance and in heat resistance, and in which the surface layer is not separated from the lined layer even if frictional connection is repeated. SOLUTION: A base material is formed, in which a surface layer 13A having a high ratio of aramid fibers has been provided on a lined layer 13B having a high ratio of cellulose fibers. In the boundary part of the lined layer 13B and the surface layer 13A, the fibers of both layers are intertwined with one another so as to be in a crossed condition nearly similar to the inside of the lined layer 13B. A wet-type friction material 13 is formed by immersing a resin adhesive into the base material and by subjecting it to heat-compression. Even if the frictional engagement is repeated 10000 times, the surface layer 13A is not separated from the lined layer 13B, and a high coefficient of dynamic friction can be secured, so that a clutch plate 10 of high quality and long life can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant wet friction material having a paper-like structure used for a fastening element in an automatic transmission and a lockup mechanism in a torque converter, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A fastening element in an automatic transmission is constructed by attaching a thin wet friction material in the form of a paper cut in an annular shape to a ring of a thin iron plate. A similar annular wet friction material is also attached to the lock-up piston in the torque converter, as shown in Japanese Patent Laid-Open No. 3-144153. The wet friction material is used in a state where the lubricating oil is impregnated in the tissue, and the oil is taken in and out from the tissue with the repetition of pressurization at the time of friction engagement and pressure release at the time of release.

A general wet friction material forms a base material in which a silica-based filler for adjusting friction performance is held in a paper-like structure in which fibers are crossed, and a fine structure structure of the base material is made into a resin. It is formed by being reinforced with a system binder. The base material of the conventional wet friction material has been formed by using a so-called paper-placing method using long cellulose fibers such as cotton as a fiber material. Specifically, a solution prepared by dispersing and dissolving cellulose fiber and a silica-based filler in water together with a predetermined dispersant and a coagulant is prepared, and the cellulose fiber and the filler are removed from the solution by passing the solution through a net. A paper-like structure was formed by straining. Then, after drying this paper-like structure, it was impregnated with a phenol resin-based binder and heated and solidified. The binder bonds the intersections of cellulosic fibers to form a tissue that can withstand the shear forces of friction. Such a wet friction material is called a paper-based friction material and has a high porosity and an excellent oil discharge property, so that the dynamic friction coefficient is stable in a wide range of the braking speed (vehicle speed).

On the other hand, a heat-resistant wet friction material formed by mixing aramid fiber with the fibrous material of the wet friction material has been put into practical use. Aramid fiber has much higher tensile strength and heat resistance than cellulose fiber,
The heat resistance and abrasion resistance of the wet friction material are improved. The heat resistance referred to here is the length of life for which a stable dynamic friction coefficient can be obtained at high temperatures. For example, aramid fiber 10
A base material of 15%, cellulose fibers 45 to 50%, and silica-based filler 35 to 45% is formed by a paper-skipping method, and the weight ratio after impregnating a dried base material with a phenol resin binder is up to 40%. Impregnated wet friction materials have been proposed.

[0005]

Cellulose fibers are extremely cheap, whereas aramid fibers are considerably expensive. Therefore, when aramid fibers are mixed with the fiber material of the wet friction material, the material cost of the wet friction material is low. Increase production cost.
However, if the proportion of aramid fibers is intentionally reduced to form a structure mainly composed of cellulose fibers, the heat resistance of the wet friction material will not be sufficiently increased.

Further, a wet friction material having a high content of aramid fibers has higher rigidity than a wet friction material having a high content of cellulose fibers, so that the adhesion of the surface to the other surface is inferior and the friction It is difficult to form a uniform oil film on the surface that affects performance. A wet friction material having a high aramid fiber content has a low dynamic friction coefficient due to insufficient oil discharge performance when the tissue is pressurized. Therefore, the wet friction material having a high content of aramid fibers has improved heat resistance as compared with the wet friction material of cellulose fibers, but the friction performance is deteriorated.

Therefore, an attempt is made to separately form a backing layer having a structure mainly composed of cellulose fibers and a surface layer mainly composed of aramid fibers and superimpose them, and impregnate them with a binder at the same time and heat-compress them to integrally bond them. It has been made.
By making the layer rich in aramid fiber extremely thin, it is possible to reduce the material cost while ensuring high heat resistance of the wet friction material, and improve the adhesion to the mating surface by the effect of the backing layer having an appropriate elastic modulus. Therefore, we try to secure a high dynamic friction coefficient. However, when the pressurization accompanying fastening and the pressure release accompanying fastening release are repeated, the structure of the wet friction material repeatedly expands and contracts in the thickness direction,
The bonded portion is destroyed and the surface layer peels off from the backing layer. Further, the repeated shearing force due to friction gradually deteriorates the structure of the bonded portion. On the other hand, if the binder is excessively impregnated, the pores of the porous friction material are filled to prevent the oil from entering and exiting, and the dynamic friction coefficient of the wet friction material is reduced.

According to the present invention, the surface layer composed mainly of aramid fibers does not separate from the backing layer composed mainly of cellulose fibers even after repeated frictional fastening, so that the oil can be smoothly transferred between the surface layer and the backing layer. Accordingly, it is an object of the present invention to provide a heat-resistant wet friction material which has both high heat resistance and high dynamic friction coefficient and is inexpensive, and a method for producing the same.

[0009]

The invention according to claim 1 is the first
A heat-resistant wet friction material having a paper-like structure in which a fibrous material and a second fibrous material are crossed with each other and adopting a material having higher heat resistance than the second fibrous material as the first fibrous material,
A surface layer with an increased proportion of the first fibrous material and a backing layer with an increased proportion of the second fibrous material, wherein the fibers of both layers penetrate into each other between the surface layer and the backing layer and are continuous. Are entangled with each other to form a crossed state substantially similar to that in the backing layer.

According to a second aspect of the present invention, in the first aspect, the first fiber material is an aramid fiber and the second fiber material is a cellulosic fiber, and the paper is used as a base material in which the surface layer is laminated on the backing layer. 45 to 50% by weight of the binder that reinforces the textured structure after impregnation, and the composition of the surface layer is 60 to 65% by weight of the aramid fiber in the weight ratio of the base material.
Cellulose fibers are adjusted to 1 to 5%, a solid filler for adjusting friction performance is adjusted to 30 to 40%, and the composition of the backing layer is such that the weight ratio of the backing layer is 10 to 10 aramid fibers.
15%, cellulose fiber is adjusted to 45 to 50%, and the filler is adjusted to 35 to 45%.

According to a third aspect of the present invention, a strainer net is placed in a container filled with a solution in which aramid fibers, cellulose fibers and a solid filler for adjusting frictional properties are dispersed, and the container is passed through the strainer net to form a container. By discharging the solution from the bottom side, in the method for producing a heat-resistant wet friction material that forms a paper-like structure on the strainer net, in the middle of discharging the initial solution with a high proportion of cellulose fibers. , A method for producing a product in which an additional solution having an increased proportion of aramid fibers is additionally charged into the container once or more.

According to a fourth aspect of the present invention, in the structure of the third aspect, the aramid fiber is 10 to 15% and the cellulose fiber is 4%.
5 to 50%, a material in which the filler is adjusted to 35 to 45% is dispersed and dissolved in water together with a predetermined dispersant or aggregating material, and the solution is used as the initial solution. % -95%, the aramid fiber is 60 to 65%, the cellulose fiber is 1 to 5%, and the filler is adjusted to 30 to 40% in water together with a predetermined dispersant and coagulant. Is a method for producing a product in which after the additional solution dispersed and dissolved in is additionally charged into the container, the solution on the strainer net is completely discharged.

According to a fifth aspect of the present invention, the first fiber material, the second fiber material, and the filler for adjusting the friction performance are dispersed in the flow path of the solution, and a strainer net is arranged to filter the fibers. In the method for producing a heat-resistant wet friction material that forms a textured structure, the ratio of the first fiber material in the solution is set to be high in the initial stage or the final stage of filtering the fibers with the strainer net and in the solution. The method for producing a product wherein the flow of the solution passing through the screen is stopped when the ratio of the first fiber material is changed.

[0014]

In the heat-resistant wet friction material according to claim 1, since the structure of the surface layer and the structure of the backing layer are entangled with each other to form a crossed state similar to that in the backing layer, the structure of the surface layer is formed. And the structure of the backing layer are continuously integrated. Therefore,
If the intersection points of all the fibers are bonded using a binder in a later step, a microstructure with the same density as in the backing layer is formed at the boundary between the surface layer and the backing layer, and the porosity and fiber density at the boundary are formed. No step or sudden change in the filler density or the binder density is formed. When pressurization and pressure release are repeated, each part in the thickness direction expands and contracts in a substantially similar manner, and stress concentration and variation in deformation amount do not occur at the boundary part.

In the heat-resistant wet friction material according to the second aspect, the composition ratio of the prototype, which is experimentally confirmed to have both heat resistance and friction performance, is shown. Since the surface layer rich in aramid fibers and the backing layer rich in cellulose fibers are joined by a continuous paper-like structure, the friction performance is improved as compared with the case where no cellulose fibers are contained. Further, the aramid fiber contained in the backing layer reinforces the paper-like structure of the cellulose fiber and enhances the shear resistance acting on the structure due to friction. The filler is held in a paper-like tissue to increase the resistance when the tissue is compressed and suppress the strain amount. In addition, the friction surface is smoothed through compression molding to form a flat and smooth surface having high friction performance. The ratio of 35 to 45% is a range in which the frictional performance of the filler can be sufficiently ensured while ensuring high shear strength and oil discharge performance of the paper-like structure.

In the method for producing the heat-resistant wet friction material according to the third aspect of the present invention, the fibers of the surface layer rich in aramid fiber and the backing layer rich in cellulose fiber are interwoven at the boundary between them to form a continuous texture structure. The paper making technique is shown. Since the initial solution for forming the backing layer is left, the solution for forming the surface layer is additionally charged, so that the fibers in the standing state of the surface of the fiber layer on the screen and the added solution are added. The fibers interlace and accumulate, and become entangled with each other. On the contrary,
When the latter solution is added after the initial solution on the strainer net is exhausted and the surface fibers are completely laid down, there is no room for the fibers to entangle at the interface between both layers, and even immediately after the papermaking or after drying. Both layers can be easily peeled off.

In the method for producing the heat-resistant wet friction material according to the fourth aspect, the concrete procedure of the paper making method, which is experimentally confirmed to have both the heat resistance and the friction performance of the finished product, is shown. In the process of discharging the solution from the bottom side of the container, the fibers and the filler in the solution accumulate on the strainer net. The filler dispersed in the solution is strained by the fine filter tissue of the deposited fibers and kept as it is in the tissue. The initial solution on the screen is 80% ~
At the stage of 95% drainage, additional solution is gently dosed. The remaining portion of the initial solution and the additional solution are partially mixed to form a structure having a composition intermediate between the surface layer and the backing layer.

In the method for producing the heat-resistant wet friction material according to the fifth aspect, the flow of the solution is temporarily stopped when changing the ratio of the first fiber material in the solution which is passed through the strainer net.
The fibers pressed against the surface of the deposited fiber layer by the flow of the solution rise into the solution and participate in the entanglement with the deposited fibers after changing the proportion of the first fiber material in the solution. A layer with an increased proportion of the first fibrous material may be strained and deposited first on the net, and a layer with an increased proportion of the second fibrous material may be strained and deposited first on the net. In any case, a wet friction material is obtained in which a layer having a high proportion of the first fibrous material and a layer having a high proportion of the second fibrous material are joined by a continuous paper-like structure.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a clutch plate and a wet friction material therefor according to an embodiment will be described with reference to FIGS. FIG.
Is an explanatory view of the structure of the clutch plate of the embodiment, FIG. 2 is an explanatory view of the structure structure of the wet friction material, FIG. 3 is an explanatory view of the method for manufacturing the base material of the wet friction material, and FIG. 4 is an evaluation method of the wet friction material. Illustration of
FIG. 5 is a diagram of the friction performance of the clutch plate of the example. In FIG. 1, (a) is a plan view of the clutch plate, and (b) is an XX sectional view of the clutch plate. In FIG. 2, (a) is a surface layer,
(B) is a backing layer.

As shown in FIG. 1A, in the clutch plate 10 of the embodiment, a wet friction material 13 is attached to a thin annular iron plate 11 having a spline 12 formed inside.
The clutch plate 10 is attached to the clutch mechanism of the automatic transmission in a state in which a plurality of clutch plates are alternately arranged with another clutch plate having a spline formed on the outer side. As shown in FIG. 1B, a wet friction material 13 having a thickness of 400 μm is arranged on both front and back surfaces of an iron plate 11 having a thickness of 1 mm. A surface layer 13A having a structure mainly composed of aramid fibers is formed on the surface side of the wet friction material 13, and a backing layer 13B having a structure mainly composed of cellulose fibers is formed at the opposite iron plate 11 side. The surface layer 13A and the backing layer 13B have almost the same thickness, and at the boundary portion between the surface layer 13A and the backing layer 13B, the fibers of both layers are intertwined with each other to form a continuous structure. The wet friction material 13 is formed by cutting out a thin and smooth paperboard-shaped material obtained by impregnating a paper-like tissue formed by a paper-punching method described later with a phenol resin binder and compressing it into a ring shape.

As the base material of the wet friction material 13, the surface layer 13A shown in FIG. 2A is arranged on the surface side of the backing layer 13B shown in FIG. 2B. Each of the backing layer 13B and the surface layer 13A has a coated paper-like fine texture structure in which filler particles JU are held in a filter-like texture in which aramid fibers AR and cellulose fibers SE are three-dimensionally interlaced. . The aramid fiber AR is a curved fiber with few branches, and the cellulose fiber SE is a fiber with many branches and many undulations. FIG. 2 schematically shows the state of bending, branching and crossing of fibers observed under a microscope.
The actual thickness of the fiber is thicker than that shown in the figure, and there is a portion reaching a thickness similar to the particle JU of the filler. When a substrate having such a tissue structure is impregnated with a phenol resin binder, the binder covers the surface of the fiber and forms a bump of the binder at the intersection of the fibers to bond them to each other. As a result, a hump-shaped structure is formed in which the intersections of the fibers do not shift due to shearing or stretching. Further, a bridge structure of a binder is formed in the gap between the fiber and the filler to position the filler in the gap between the fibers.

In the surface layer 13A, the aramid fiber AR is 60 to 65% and the cellulose fiber SE is 1 to 5 in terms of weight ratio in the base material before impregnating the phenol resin binder.
%, And the silica-based filler occupies the remaining 30 to 40%. In the backing layer 13B, the aramid fiber AR is 10 to 15% and the cellulose fiber SE is 45 to 15% in terms of the weight ratio in the base material before impregnating the phenolic resin binder.
50%, silica-based filler is the remaining 35-45%
Occupy. Here, the reason why the ratio of the filler in the surface layer 13A is lower than that in the backing layer 13B is to secure the porosity of the surface layer 13A. That is, when the proportion of the aramid fiber AR increases, it is necessary to increase the impregnation amount of the phenol resin binder to strengthen the fiber bond.
Since increasing the impregnation amount of the phenol resin binder lowers the porosity of the tissue, the proportion of the filler is reduced to secure a sufficient gap between the fibers.

The aramid fiber AR is a polyamide fiber whose molecular skeleton is aromatic and decomposes at 400 ° C. or higher,
Cellulose fiber SE with high heat resistance that carbonization begins
Compared with, it is orders of magnitude more expensive. Further, since the entanglement of the fibers is weaker than that in the case of the cellulose fiber SE, it is necessary to increase the impregnated amount of the phenol resin binder in the tissue in which the ratio of the aramid fiber AR is high. On the other hand, the cellulose fiber SE is a natural fiber obtained from cotton, and although it can be obtained at a low cost, it already begins to deteriorate at 140 ° C., and at 160 ° C. or higher, it causes a rapid decrease in strength due to intramolecular dehydration. However, since the entanglement and bonding between the fibers are strengthened by performing the process of rubbing the fibers to make the surface fluffy, the amount of the phenol resin binder impregnated is small in a tissue with a high proportion of cellulose fibers SE. Also, the intersections of fibers are difficult to shift.

The solid filler is diatomaceous earth (Si
O _2), wherein calcium carbonate (CaCO ₃₎ or the like, by increasing the substantial contact area to form a smooth friction surface to fill the gap of the mesh of fibrous tissue, suppress the abrasion and cutting of the fibers And increase the friction coefficient of the friction surface. It also reinforces the internal fibrous structure and adjusts the porosity in the structure to ensure the required oil drainage performance.

As the phenol resin binder, an epoxy modified phenol resin or an elastomer modified phenol resin can be used. Since the epoxy-modified phenolic resin has a high hardness, the heat resistance and abrasion resistance of the structure are enhanced, but the friction coefficient of the friction surface is reduced. Since the elastomer-modified phenolic resin has a soft property, the friction coefficient of the friction surface is increased, but the heat resistance and abrasion resistance of the structure are slightly reduced. In the example,
Uses a straight resole type phenolic resin binder. As described above, when the proportion of the aramid fiber AR is increased, it is necessary to increase the impregnated amount of the phenol resin binder, so that in the wet friction material of the example, the surface layer 13A is used.
In order to secure the bonding of the tissue, the amount of the phenol resin binder impregnated is increased so that the weight ratio after impregnation is 45 to 50%.

As a result of a comparative experiment in which the impregnated amount of the phenolic resin binder was changed in several steps in the base material used in the examples, when the impregnated amount of the phenolic resin binder was 45% or less, the aramid fiber 21 of the surface layer 13A was It was found that the binding force was insufficient, and when it was 50% or more, the pores in the tissue were closed, the oil discharge performance was insufficient, and the friction coefficient was reduced. However, 45
The value of ~ 50% is not absolute.
It is considered that the optimum impregnated amount of the phenol resin binder will be slightly different if the type and composition ratio of the aramid fiber AR, the cellulose fiber SE and the filler change.

In the embodiment, the paper making device 3 shown in FIG.
No. 0 is used to form the base material of the wet friction material having the continuous texture structure of the surface layer 13A and the backing layer 13B from the solution 41 and the solution 42. The cross-section of the paper making device 30 is 30c.
An outlet 32 and a water supply port 33 are arranged on the bottom of a rectangular parallelepiped container 31 of m × 30 cm, and an outlet of a solution supply port 34 is arranged at an intermediate height of the container 31. A valve 32 is provided at the outlet 32.
B, a valve 33B is provided at the water supply port 33, and a valve 34B is provided at the outlet of the supply port 34. A 25 cm × 25 cm wire net 35 for filtering out the fibers is horizontally arranged on the bottom side of the container 31. A limit switch 37 for detecting the liquid level is attached to the side surface of the container 31 so that the height can be adjusted. The valve 32B of the outlet 32 is electrically operated,
It can be automatically closed in conjunction with the limit switch 37.

Solution 41 for forming the backing layer 13B
Is 47% of cotton pulp having a diameter of 10 to 12 μm and a length of 2 to 5 mm, which has been treated by rubbing fibers to make the surface fluffy, and similarly treated, a diameter of 8 to 12 μm and a length of 1 to 2 mm. 13% aramid fiber, average particle size 10
A silica-based filler having 20 μm of diatomaceous earth as a main component was mixed to 40% to dissolve 12.5 g of a solid content, and aluminum sulfate (Al ₂ (SO ₄ ) ₃ ) as a dispersant was added to 6% of the solid content to aggregate. As an agent, a polymer flocculant (trade name Hi-Holder) is added at 0.15% of the solid content. Surface layer 13
The solution 42 for forming A is 3 parts of cotton pulp.
%, Aramid fiber 62%, silica filler 35%, 12.5 g of solid content is dissolved in water, 6% of dispersant and 0.15% of coagulant are added. .

The procedure for forming the base material on the metal net 35 is as follows. (1) Open the valve 33B of the water supply port 33 to open the wire mesh 35
The water is stored in the container 31 to a level higher by 2 to 3 cm and the valve 33B is closed. (2) The entire amount of the solution 41 is poured from the upper part of the container 31, the valve 33B is opened again to supply water to dilute the solution 41 in the container 31, and the liquid level is raised to a level of 5 cm from the upper part of the container 31. (3) The diluted solution 41 in the container 31 is sufficiently stirred and then the valve 32B of the discharge port 32 is opened to drain the solution. At the initial stage of drainage through the drainage port 32, since the amount of fibers deposited on the wire netting 35 is small, the drainage contains a large amount of the filler, but when the fibers are slightly deposited, the filler in the solution becomes the backing layer. It is efficiently captured by the fine tissue structure. (4) 15% of the height from the highest liquid level to the wire mesh 35
The limit switch 37 is activated at the stage when the drainage is advanced to the height, and the valve 32B is automatically closed immediately.

(5) Supply the well-stirred solution 42 to the supply port 3
4, the valve 34B is opened, and the solution 41 remaining in the container 31 is gently poured. (6) The valve 34B is closed and the entire solution in the container 31 is gently stirred at a speed at which the structure deposited on the surface of the wire netting 35 is not collapsed, and then the valve 32B of the discharge port 32 is opened to restart drainage. In the process of depositing the surface layer 13A, the particles of the filler having a large amount of aramid fibers AR and permeating the rough texture are captured by the backing layer 13B, so that the filler of the backing layer 13B continuously increases. Therefore, despite the loss of the filler in the initial stage of drainage of (3), the ratio of the filler in the backing layer 13B can be finally set higher than that in the surface layer 13A. In other words, the backing layer 13B is first deposited on the wire netting 35 and the surface layer 13A is deposited later, which is the reason why the above-mentioned composition of the solutions 41 and 42 causes the filling material of the surface layer 13A and the backing layer 13B at the base material stage. Can be controlled to the above ratio. (7) The entire solution in the container 31 is drained through the outlet 32, the wire netting 35 is exposed in the air, and the wire netting 35 is removed together with the tissue deposited on the surface. (8) Peel off the structure deposited on the surface from the wire net 35,
Dry after removing excess water.

The base material of the wet friction material which has been dried to completely remove water has a thickness of about 1 mm. This base material was impregnated with a straight resole type phenolic resin binder to a weight ratio of 48% after impregnation and heat cured. The wet friction material paper thus formed is cut into a ring shape and attached to an iron plate 11 coated with an adhesive phenol resin, and the whole is hot-pressed to form the wet friction material 13 of the final 400 μm. Compressed to thickness, clutch plate 10 is formed.

The clutch plate 10 was evaluated by producing a clutch plate of a comparative example in which only the wet friction material was changed, and using a SAE # 2 tester as a repeated braking endurance tester, heat resistance (long-term stability of friction coefficient). ) Was compared. The SAE # 2 tester tests the friction plate 10 under operating conditions similar to the multiple disc brakes of an automatic transmission, as shown in FIG. The inner rotating member 55 is driven by the motor 51 and rotates integrally with the flywheel 52. The outer member 54 is restrained from rotating by a load cell 57 for measuring a frictional force.

The clutch plate 10 whose rotation is restricted by the rotating member 55 and the separator plate 53 whose rotation is restricted by the outer member 54 are alternately superposed on each other, and axially passed through a load cell 58 for measuring the pressing force. Compress. A frictional force is generated between the rotating clutch plate 10 and the separator plate 53 whose rotation is fixed to brake the rotation of the flywheel 52. Specifically, the flywheel 5
2 is driven by the motor 51 to a predetermined rotation speed to shift to inertial rotation, and then the piston 56 is moved in the axial direction to frictionally engage the clutch plate 10 with the separator plate 53 and stop the rotation of the flywheel 52. Let This series of operations is repeated 10,000 times or more. The wet friction material 13 on the surface of the clutch plate 10 is oil-supplied under conditions suitable for use in an automatic transmission.

The test conditions for the dynamic friction test are as follows: oil temperature: 120 ° C, inertia: 0.203 kgm ² (2.0 kgfc
m ² ), pressing surface pressure: 1106 kPa (11.3 kg)
f / cm ² ), pressing pressure time: 2 seconds, pressing rise time: 0.1 to 0.15 seconds, initial input rotation speed: 30
00 rpm, endurance repetition rate: 2 times / minute (motor O
N / OFF time 10 seconds / 20 seconds), number of cycles: 100
00 cycle, friction coefficient measurement: every 500 cycles. The test conditions of the static friction test are: oil temperature: 120 ° C., pressing surface pressure: 1106 kPa, rotation speed: 0.7 rpm, test time: about 5 seconds after the start of rotation (motor ON time 5
Second), test start timing: start immediately after the end of the dynamic friction test (20 seconds after the dynamic friction test motor is turned off).

The wet friction material of the comparative example was impregnated with a phenol resin binder to a weight ratio of 40% after impregnating the base material formed by using the paper making device of FIG. It is manufactured by attaching it to a clutch plate and heating and compressing it. The aramid fiber, cellulose fiber, and silica-based filler used were the same as those used in the examples, and the respective weight ratios in the base material were 13%, 47%, and 40%.
%.

The test results of the dynamic friction test are shown in FIG. In the initial stage of the repeated test, although the proportion of aramid fibers in the surface texture was increased, a dynamic friction coefficient almost equal to that of the comparative example having a large amount of cellulose fibers in the surface texture could be secured. Even when the number of repetitions exceeded 6000 times, the decrease in the dynamic friction coefficient as in the comparative example was not observed, and even when the number of repetitions was 10,000, the decrease in the dynamic friction coefficient was very slight. Although not shown in the test results, the static friction test also confirmed the advantages over the wet friction material of the comparative example almost in the same manner as the dynamic friction coefficient. Therefore, stable clutch operation is ensured for a long period of time, and the life of the clutch plate 10 is greatly improved.

[0037]

According to the first aspect of the present invention, since the surface layer and the backing layer are connected by a continuous structure, the surface layer does not separate from the backing layer even if frictional fastening is repeated. Also,
When the whole is impregnated with the binder, there is no shortage or excess of the binder at the boundary between the surface layer and the backing layer, and the density, hardness and strength of the structure do not vary greatly in the thickness direction of the wet friction material. , Even if the compression and the pressure release are repeated, the tissue of the boundary portion and the adjacent portion is not destroyed. In addition, the oil in and out of the wet friction material is not impeded to impair the friction coefficient of the surface layer. Since the backing layer increases the proportion of the second fiber material to reduce the required amount of the second fiber material as a whole, when the first material having high heat resistance is more expensive than the second fiber material, A wet friction material having both heat resistance and friction performance can be manufactured at low cost.

According to the second aspect of the present invention, it is possible to obtain a long-life wet friction material having a good friction coefficient under the operating conditions of the automatic transmission. It is possible to manufacture a clutch plate having a friction coefficient as high as that of a conventional wet friction material mainly composed of cellulose fibers and capable of ensuring almost twice the life.

According to the invention of the manufacturing method of claim 3, the fibers of the surface layer are started to be deposited before the fibers of the surface of the back strike layer collapse, so that the fibers are efficiently interlaced and the surface layer It is easy to form a continuous tissue structure connecting the underlayer with the backing layer. In addition, since a rough tissue with many aramid fibers is deposited on a fine tissue with many cellulose fibers, the filler can be efficiently trapped in the tissue, and compared with the case where the order of deposition is reversed, The proportion of the filler in the base material can be precisely and easily adjusted by adjusting the components of the additional solution.

According to the invention of the manufacturing method of claim 4, it is possible to manufacture a high-quality wet friction plate which has been experimentally confirmed to have a high friction coefficient and a long life under the use condition of the automatic transmission.

According to the invention of the manufacturing method of claim 5, the fibers of the layer to be deposited later are deposited in a state where the fibers on the surface of the layer previously deposited are raised, so that the fibers are efficiently interlaced. , A continuous texture structure connecting the surface layer and the backing layer can be easily formed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a structure of a clutch plate according to an embodiment.

FIG. 2 is a schematic explanatory view of a texture structure of a base material of a wet friction material.

FIG. 3 is an explanatory diagram of a method for manufacturing a base material of a wet friction material.

FIG. 4 is an explanatory diagram of an evaluation method of a wet friction material.

FIG. 5 is a diagram of the friction performance of the clutch plate of the example.

[Explanation of symbols]

 10 Clutch Plate 11 Iron Plate 12 Spline 13 Wet Friction Material 13A Surface Layer 13B Backing Layer AR Aramid Fiber SE Cellulose Fiber JU Filler Particles 30 Paper Pruning Device 31 Container 32 Discharge Port 33 Water Supply Port 34 Supply Port 32B, 33B, 34B Valve 35 Wire Mesh 37 Limit Switch 41 Solution A 42 Solution B 51 Motor 52 Flywheel 53 Separator Plate 54 Outer Member 55 Rotating Member 56 Piston 57, 58 Load Cell

Claims (5)

[Claims] 1. A heat-resistant wet friction material having a paper-like structure in which a first fibrous material and a second fibrous material are interlaced, and a material having a higher heat resistance than the second fibrous material is adopted as the first fibrous material. In the method, a surface layer having an increased proportion of the first fibrous material and a backing layer having an increased proportion of the second fibrous material are provided, and the fibers of both layers intrude into each other between the surface layer and the backing layer. The heat-resistant wet friction material is characterized in that it is continuously entangled with each other and is in the same crossing state as in the backing layer. 2. The first fiber material is an aramid fiber and the second fiber material is a cellulose fiber, and a base material having the surface layer superposed on the backing layer is provided with a binder for reinforcing the paper-like structure. 45-5 by weight ratio after impregnation
The surface layer is impregnated with 0%, and the surface layer has a weight ratio in the base material of 60 to 65% aramid fibers, 1 to 5% cellulose fibers, and 30 to 40 solid fillers for adjusting friction performance. %, And the composition of the backing layer is such that the aramid fiber is 10 to 15% and the cellulose fiber is 45 to 50 by weight ratio in the base material.
%, The filler is adjusted to 35 to 45%, The heat resistant wet friction material according to claim 1, wherein 3. A strainer net is placed in a container filled with a solution in which aramid fibers, cellulose fibers and a solid filler for adjusting frictional performance are dispersed, and the solution is passed through the strainer net from the bottom side of the container. In the method for producing a heat-resistant wet friction material that forms a paper-like structure on the strainer net by discharging, the proportion of aramid fibers is in the middle of discharging the initial solution with a high proportion of cellulose fibers. A method for producing a heat-resistant wet friction material, characterized in that an additional solution having a higher temperature is added to the container once or more. 4. A solution prepared by dispersing and dissolving a material in which aramid fiber is adjusted to 10 to 15%, cellulose fiber is adjusted to 45 to 50% and the filler is adjusted to 35 to 45% in water together with a predetermined dispersant and a coagulant. Used as the initial solution, when the initial solution on the strainer net was discharged to 80% to 95%, the aramid fiber was 60 to 65%, the cellulose fiber was 1 to 5%, and the filler was 30%. It is characterized in that after the additional solution in which the material adjusted to -40% is dispersed and dissolved in water together with a predetermined dispersant and a coagulant is additionally charged into the container, the solution on the strainer net is completely discharged. The method for producing the heat resistant wet friction material according to claim 3. 5. A paper-like structure is formed by arranging a strainer net in a flow path of a solution in which a first fiber material, a second fiber material and a filler for adjusting frictional properties are dispersed and straining the fibers. In the method for producing a heat-resistant wet friction material, the ratio of the first fiber material in the solution is set high in the initial stage or the final stage of filtering the fibers with the strainer net, and the first fiber material in the solution is also used. The method for producing a heat-resistant wet friction material, characterized in that the flow of the solution passing through the screen is stopped when the ratio of the above is changed.