JP2007119570A - Friction material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction material capable of attaining excellent initial characteristics and a high positive μ-V gradient while keeping ultra-high heat resistance without undergoing strength decrease. <P>SOLUTION: Base fibers and a filler are made into a paper-like sheet (S10). The paper-like sheet is impregnated with a thermosetting resin (S11), and the impregnated sheet is dried in a fashion in which the temperature of a friction surface is lower, and the temperature of a surface opposite to the friction surface is higher (S12). Because the resin in the friction material moves from the lower temperature part to the higher temperature part as the result of pull by the solvent which moves to the higher temperature part and becomes dry, the distribution of resin quantities in the thickness direction can be highest near the surface opposite to the friction material and can be lowest near the friction surface. The thermosetting resin is heat-cured (S13), and, of the part made entirely of the resin on the friction surface, an about 10±5 μm ultrasurface part is removed by grind with an abrasive (S14). The thus obtained friction material 1 can attain an excellent positive μ-V gradient because of the reduced influence of the resin as well as the low resin concentration near the surface of the friction surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a friction material for a friction material engaging device provided with a plurality of or a single friction plate used in an automatic transmission such as an automobile or a transmission such as a motorcycle, and a method of manufacturing the friction material.

  In wet friction engagement devices such as multi-plate clutches used in lubricating oil, wet friction materials such as saddle-bonded gold, carbon or cork are also known as wet friction materials for wet friction plates. However, a paper-type wet friction material also called “paper friction material” is generally used.

  This wet friction material is made by impregnating a paper binder obtained by making a base fiber such as pulp or aramid fiber and a filler such as a friction modifier or a body filler with a resin binder made of a thermosetting resin. It is formed by heat-curing and is not only lightweight and inexpensive, but also has a high oil absorbency because it is porous and relatively elastic, and it is also compared with heat resistance, wear resistance, etc. It has features such as excellent performance.

  Here, the presence of resin near the friction surface of the friction material is one of the factors that determine the heat resistance (particularly heat spot resistance) of the friction material. It is thought that it is desirable that the amount of resin near the friction surface is small because it becomes harder and heat resistance decreases, but if the amount of resin in the friction material is reduced to reduce the amount of resin near the friction surface, the strength as a friction material Therefore, the balance between heat resistance and strength is ensured by blending the minimum necessary resin. In recent years, however, the friction material has been required to have even higher heat resistance.

  Therefore, in Patent Document 1, the resin amount in the vicinity of the friction surface of the friction material is made lower than the portion having the highest resin amount in the resin amount distribution in the thickness direction of the friction material, thereby reducing the strength without causing a decrease in strength. An invention of a friction material having ultra-high heat resistance and a manufacturing method thereof is disclosed.

Patent Document 2 discloses a flat surface for treating a friction surface with sliding pressure and frictional heat, a plurality of grooves formed on the flat surface, the flat surface, and a side surface of the groove. A patent invention of an initial smoothing method for a wet friction member characterized in that polishing is performed using only a polishing surface composed of a polishing corner portion formed therebetween. By such an initial leveling method, it is possible to perform the initial leveling of the wet friction member in a shorter time and at a lower cost than when using a conventional initial leveling device.
JP 2004-205036 A Japanese Patent No. 3658168

  However, the friction material is required to have excellent friction characteristics (μ-V positive gradient, initial characteristics, etc.) as well as ultra-high heat resistance. The friction material described in the above-mentioned Patent Document 1 can also obtain a certain level of good friction characteristics, but still requires a higher μ-V positive gradient. Moreover, although the patent invention described in Patent Document 2 stabilizes the initial characteristics, it cannot be expected to have an effect of obtaining a high μ-V positive gradient.

  Then, this invention makes it a subject to provide the friction material which can obtain the outstanding initial characteristic and high micro-V positive gradient property, and its manufacturing method, maintaining ultrahigh heat resistance, without raise | generating strength reduction. To do.

  In the friction material according to the first aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is formed lower in the vicinity of the friction surface than the portion with the highest resin amount in the thickness direction. The extreme surface layer portion of the friction surface is polished in air.

  Here, “in air” means that polishing is not performed in a liquid (lubricating oil) as in the patent invention described in Patent Document 2, but is performed in a dry state. Further, the “pole surface layer portion” means a surface layer portion having a very thin friction surface, and numerically falls within the range of several μm to several tens μm from the friction surface.

  The friction material according to a second aspect of the present invention is the friction material according to the first aspect, wherein the resin amount of the friction material is lower by 5% or more on the friction surface side and the anti-friction surface side.

  A friction material according to a third aspect of the present invention is the friction material according to the first aspect, wherein the amount of resin of the friction material is reduced by 5% or more on the friction surface side between the friction surface side and the friction material side.

  The friction material according to a fourth aspect of the present invention is the friction material according to any one of the first to third aspects, wherein the distribution of the resin amount of the friction material is continuously changed.

  The friction material according to a fifth aspect of the present invention is the friction material according to any one of the first to third aspects, wherein the distribution of the resin amount of the friction material is changed discontinuously.

  In the method for manufacturing a friction material according to the sixth aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is greater than the portion of the resin amount in the vicinity of the friction surface having the highest resin amount in the thickness direction. And a step of surface polishing the extreme surface layer portion of the friction surface in the air.

  According to a seventh aspect of the present invention, there is provided a friction material manufacturing method according to the sixth aspect of the present invention, wherein the distribution of the amount of resin in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is in the thickness direction. The step of forming the resin so as to be lower than the highest resin amount portion includes a step of lowering the temperature of one surface and / or increasing the temperature of the other surface when drying the friction material. .

  The friction material manufacturing method according to the invention of claim 8 is the structure according to claim 6, wherein the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is such that the vicinity of the friction surface is in the thickness direction. The step of forming the resin material so as to be lower than the portion with the highest resin amount is to dry the friction material with the friction surfaces of the two friction materials being overlapped with each other and then separately or overlapping. It includes a step of curing at a high temperature while keeping them together.

  According to a ninth aspect of the present invention, there is provided the friction material manufacturing method according to the sixth aspect of the present invention, wherein the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is the vicinity of the friction surface in the thickness direction. The step of forming the resin material so as to be lower than the highest resin amount portion forms a friction material having two or more different resin amounts, and at least the friction material having one or more different resin amounts. It includes a step of superimposing and integrating before drying is completed.

  According to a tenth aspect of the present invention, there is provided a friction material manufacturing method according to the sixth aspect, wherein the resin material distribution in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is such that the vicinity of the friction surface is in the thickness direction. The step of forming the resin material so as to be lower than the highest resin amount portion of the friction material is further impregnated with the resin of the friction material when the friction material is dried after the resin is additionally impregnated on one surface of the friction material. The process includes a step of drying under a predetermined temperature condition while applying centrifugal force in the thickness direction with the side as the outside.

  The method for manufacturing a friction material according to an invention of claim 11 is the method according to any one of claims 6 to 10, wherein the step of polishing the surface of the extreme surface layer of the friction surface in air is performed by the friction material. After the step of forming the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side so that the vicinity of the friction surface is lower than the portion of the highest resin amount in the thickness direction, the friction surface of the friction material Is a step of polishing 10 μm ± 5 μm.

  In the friction material according to the first aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is formed so that the vicinity of the friction surface is lower than the portion with the highest resin amount in the thickness direction. The extreme surface layer portion of the friction surface is polished in air. Here, the extreme surface layer portion means a surface layer portion having an extremely thin friction surface, and the specific depth is within a range of several μm to several tens μm from the friction surface.

  As a method for obtaining a high μ-V positive gradient, it is effective to improve the flexibility of the surface layer of the friction material and to suppress the influence of the resin contained in the friction material. Therefore, by reducing the amount of resin near the friction surface in this way and polishing and removing only the resin on the extreme surface portion of the friction surface, the resin concentration near the friction surface is reduced and flexibility is improved. In addition, since the influence of the resin is reduced, the friction characteristics are improved, and excellent initial characteristics and high μ-V positive gradient characteristics can be obtained while maintaining ultrahigh heat resistance.

  In this way, the friction material can obtain excellent initial characteristics and high μ-V positive gradient properties while maintaining ultrahigh heat resistance without causing a decrease in strength.

  In the friction material according to the invention of claim 2, the resin amount of the friction material is lowered by 5% or more on the friction surface side between the friction surface side and the anti-friction surface side. Therefore, in addition to the effect of claim 1, since the amount of resin near the friction surface is lower than that near the anti-friction surface, the heat resistance and heat spot resistance are remarkably improved, and the super high heat resistance It becomes a friction material. In addition, since the distribution of the resin amount in the thickness direction of the friction material can be determined in the drying step of the friction material, it is possible to obtain an ultra-high heat resistance friction material at low cost without causing a decrease in strength.

  In the friction material according to the invention of claim 3, the resin amount of the friction material is reduced by 5% or more on the friction surface side between the friction surface side and the friction material side. Therefore, in addition to the effect of claim 1, since the amount of resin near the friction surface is lower than the inside of the friction material, the heat resistance and heat spot resistance are remarkably improved, and the friction of ultra high heat resistance Become a material. In addition, since the distribution of the resin amount in the thickness direction of the friction material can be determined in the drying step of the friction material, it is possible to obtain an ultra-high heat resistance friction material at low cost without causing a decrease in strength.

  In the friction material according to the invention of claim 4, the distribution of the resin amount of the friction material is continuously changed. Therefore, in addition to the effect according to any one of claims 1 to 3, the heat resistance and heat spot resistance are remarkably improved by continuously changing the resin amount distribution of the friction material. And it becomes a friction material with super high heat resistance. In addition, the distribution of the resin amount in the thickness direction of the friction material can be determined in the drying step of the friction material, and ultrahigh heat resistance can be imparted at low cost without causing a decrease in strength. Further, since the distribution of the resin amount of the friction material is continuously changed, mechanical stress is not concentrated on a specific portion.

  In the friction material according to the invention of claim 5, the distribution of the resin amount of the friction material is changed discontinuously. Therefore, in addition to the effect according to any one of claims 1 to 3, the resin amount distribution in the thickness direction of the friction material is obtained by discontinuously changing the resin amount distribution of the friction material. Can be determined by superposition, and at an arbitrarily low cost, the heat resistance and heat spot resistance are remarkably improved, resulting in an ultra-high heat resistance friction material.

  In the friction material manufacturing method according to the sixth aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is greater than that of the portion having the highest resin amount in the thickness direction near the friction surface. A step of forming the surface to be lowered, and a step of surface polishing the extreme surface layer portion of the friction surface in air.

  As a method for obtaining a high μ-V positive gradient, it is effective to improve the flexibility of the surface layer of the friction material and to suppress the influence of the resin contained in the friction material. Therefore, the resin concentration in the vicinity of the friction surface is reduced by forming the resin in the vicinity of the friction surface to be low and removing only the resin on the extreme surface layer portion of the friction surface by polishing the surface. To produce a friction material with improved initial characteristics and high μ-V positive gradient property while maintaining ultra-high heat resistance with improved flexibility and reduced influence of resin. Can do.

  In this way, the friction material manufacturing method can obtain excellent initial characteristics and high μ-V positive gradient characteristics while maintaining ultrahigh heat resistance without causing strength reduction.

  In the friction material manufacturing method according to the seventh aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is greater than the portion of the resin amount in the vicinity of the friction surface having the highest resin amount in the thickness direction. The step of forming the friction material includes a step of lowering the temperature of one surface and / or increasing the temperature of the other surface when the friction material is dried.

  In this way, by adding a temperature difference of high and low on both surfaces of the friction material, in addition to the effect of claim 6, the resin in the friction material moves to the high temperature part and is dragged by the solvent that is dried to lower the temperature. Therefore, the distribution of the resin amount in the thickness direction is the lowest in the vicinity of one surface, and an extremely high heat-resistant friction material can be manufactured.

  In the friction material manufacturing method according to the eighth aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is greater than the portion where the friction surface vicinity has the highest resin amount in the thickness direction. The step of forming the lower friction material includes a step of drying the friction material with the friction surfaces of the two friction materials being overlapped and then being cured at a high temperature separately or overlapping. .

  Therefore, in addition to the effect of the sixth aspect, drying does not occur from the abutting friction surfaces, and the solvent dries from the anti-friction surface on the outside, so that the resin in the friction material is also dragged. The distribution of the resin amount in the thickness direction is highest near the anti-friction surface and lowest near the friction surface, and an ultra-high heat-resistant friction material can be manufactured.

  In the friction material manufacturing method according to the ninth aspect of the present invention, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is greater than the portion of the resin amount in the vicinity of the friction surface having the highest resin amount in the thickness direction. In the process of forming the lower friction material, two or more friction materials having different resin amounts are formed, and at least the friction materials having different one or more resin amounts are overlapped and integrated before completion of drying. The process of carrying out is included.

  Therefore, in addition to the effect described in claim 6, a plurality of appropriately dried friction materials of any resin amount are formed, and they are combined, and the distribution of the resin amount in the thickness direction is the highest near the anti-friction surface, Since it is the lowest in the vicinity of the friction surface, an ultra-high heat-resistant friction material can be manufactured.

  In the friction material manufacturing method according to the invention of claim 10, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is greater than the portion of the resin amount in the vicinity of the friction surface having the highest resin amount in the thickness direction. The step of forming the material to be lowered is that the friction material is additionally impregnated on one side of the friction material and then the friction material is further impregnated on the outer side, and the centrifugal force is applied in the thickness direction. A step of drying at a predetermined temperature condition.

  Therefore, in addition to the effect of the sixth aspect, the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side on the side additionally impregnated with the resin of the friction material is obtained by friction using centrifugal force. The vicinity of the surface can be formed lower than the portion with the highest resin amount in the thickness direction.

  In the friction material manufacturing method according to the invention of claim 11, the step of surface polishing the extreme surface layer portion of the friction surface in the air is performed by the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material. This is a step of polishing the friction surface of the friction material by 10 μm ± 5 μm after the step of forming the distribution so that the vicinity of the friction surface is lower than the portion with the highest resin amount in the thickness direction.

  As a result of accumulating earnest experimental research, the present inventors have found that the thickness of the resin alone on the friction surface of the friction material is 10 μm ± 5 μm, and the influence of the resin by polishing the friction surface of the friction material by 10 μm ± 5 μm. Has been found to be remarkably suppressed, and the present invention has been completed based on this finding.

  In this way, the friction material manufacturing method can obtain a high μ-V positive gradient property while maintaining ultrahigh heat resistance without causing a decrease in strength.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.

  FIG. 1 is a flowchart showing an outline of a method for manufacturing a friction material according to an embodiment of the present invention. FIG. 2 is a diagram showing the μ-V positive gradient property as a result of measuring the friction characteristics at different surface pressures in Example 1 of the friction material according to the embodiment of the present invention in comparison with the comparative example. FIG. 3 is a diagram showing the μ-V positive gradient as a result of measuring the friction characteristics at different surface pressures in Example 2 of the friction material according to the embodiment of the present invention, in comparison with the comparative example. FIG. 4 is a schematic diagram showing a mechanism for improving the friction characteristics of the friction material according to the embodiment of the present invention. FIG. 5 is a diagram showing a contribution ratio of the friction material according to the embodiment of the present invention to the surface pressure of the treatment.

  First, a method for manufacturing a friction material according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, the friction material 1 of the present embodiment is a resin-impregnated type paper-based wet friction material. First, the base fiber (pulp, aramid fiber, etc.) and the filler (friction modifier or constitution) To make a paper body (step S10). Next, the papermaking body is impregnated with a thermosetting resin (step S11). In this embodiment, a phenol resin is used as the thermosetting resin.

  Subsequently, the temperature of the friction surface is lowered and the temperature of the anti-friction surface is raised and dried (step S12). Since the resin in the friction material has the property of moving from the low temperature part to the high temperature part by being dragged by the solvent that moves to the high temperature part and dries, the distribution of the resin amount in the thickness direction is the highest near the anti-friction surface. It becomes the lowest near the friction surface. Hereinafter, the process of reducing the distribution of the resin amount in the thickness direction in the vicinity of the friction surface as in step S12 is referred to as “migration”.

  Next, the entire friction material is further heated to a high temperature to heat and cure the thermosetting resin (step S13), and then the friction surface is polished with an abrasive (step S14). In the present embodiment, this surface polishing step polishes the friction surface only at the extreme surface layer portion of about 10 μm ± 5 μm. The reason for this is that the portion of the friction surface where only the thermosetting resin exists is only about 10 μm ± 5 μm of the surface of the friction surface, and the effect of the resin is greatly reduced by polishing and removing only this portion. This is because it can. Thus, the friction material 1 according to the present embodiment is manufactured.

  Here, there are various other methods as the migration method in step S12. For example, after naturally drying for 24 hours or more with the friction surfaces of the two friction materials overlapped, they are separated or overlapped. It can also be produced by curing at a high temperature together. Also in this case, drying does not occur from the abutted friction surface, and the solvent is dried from the anti-friction surface on the outer side, so the resin amount distribution in the thickness direction is the highest near the anti-friction surface, and the friction surface The lowest in the vicinity.

  The method for reducing the amount of resin near the friction surface is not limited to these two methods, but may be various other methods such as decompression, pressurization, centrifugal separation, spraying, ripping, roller single-sided coating, and the like. Further, in this embodiment, the resin-impregnated friction material has been described as an example. However, the friction material of the present invention is not limited to the resin-impregnated type, and may contain a resin as a component including a resin laminate type. It applies to any friction material.

  Next, the friction characteristic (μ-V characteristic) of the friction material 1 according to the present embodiment manufactured as described above was measured using an LVFA tester. As the friction material 1 according to the present embodiment, two types of manufactured products are manufactured: Example 1 with a relatively high resin rate and high density as a whole and Example 2 with a relatively low resin rate and low density. The friction characteristics were measured.

  For comparison, the same high resin ratio and high density as in Example 1, Comparative Example 1 in which neither migration nor surface polishing was performed, Comparative Example 2 in which migration was not performed and only surface polishing was performed, Migration was performed but surface polishing was performed Comparative Example 3 which was not performed, Comparative Example 4 which was the same low resin ratio and low density as in Example 2 and which was not subjected to migration or surface polishing, Comparative Example 5 which was subjected only to surface polishing without performing migration, and migration was performed However, six types of friction materials of Comparative Example 6 that were not subjected to surface polishing were also manufactured, and the friction characteristics were measured.

  The measurement conditions were as follows: the friction material size was 130 mm outer diameter, 110 mm inner diameter, lubricating oil ATF, lubricating oil amount 500 ml / min, oil temperature 40 ° C., 80 ° C., 120 ° C., friction rotation speed 0 rpm → 400 rpm → 0 rpm, surface pressure 0. It was performed at 4 MPa, 1.0 MPa, and 1.4 MPa.

  First, the measurement result in the case of the oil temperature of 40 degreeC of Example 1, Comparative example 1, Comparative example 2, and Comparative example 3 is demonstrated with reference to FIG. As the “gradient amount”, a value obtained by subtracting the value of μ at the frictional rotation speed of 50 rpm from the value of μ at the frictional rotation speed of 400 rpm is shown.

  As shown in FIG. 2, in Comparative Example 1 in which neither migration nor surface polishing was performed, a remarkable μ-V negative gradient property was exhibited, and the negative value of the gradient amount increased as the surface pressure increased. It has become. In Comparative Example 2 in which only surface polishing was performed, the gradient was almost zero at any surface pressure, and an improvement was seen compared to Comparative Example 1, but the gradient amount was still a slightly negative value. In Comparative Example 3 in which only migration was performed, the slope was almost zero when the surface pressure was 0.4 MPa, but the negative value of the slope amount increased as the surface pressure increased.

  On the other hand, in Example 1 according to the present embodiment, a remarkable μ-V positive gradient is shown, the initial characteristics are good, and even if the surface pressure increases, a significant μ-V positive gradient is obtained. The gradient is maintained.

  Next, the measurement result in the case of the oil temperature of 40 degreeC of Example 2, Comparative example 4, Comparative example 5, and Comparative example 6 is demonstrated with reference to FIG. As shown in FIG. 3, in Comparative Example 4 in which neither migration nor surface polishing was performed, the slope was nearly zero when the surface pressure was 0.4 MPa, but the slope amount decreased as the surface pressure increased. The value of becomes larger, indicating a remarkable μ-V negative gradient.

  On the other hand, in Comparative Example 5 in which only surface polishing was performed, a μ-V positive gradient was shown in the case of a surface pressure of 0.4 MPa, but the value of the gradient amount became negative as the surface pressure increased, The gradient is almost zero. Further, in Comparative Example 6 in which only migration was performed, a remarkable μ-V positive gradient was exhibited when the surface pressure was 0.4 MPa, but the value of the gradient amount became negative as the surface pressure increased. The larger the surface pressure, the more remarkable μ-V negative gradient.

  On the other hand, in Example 2 according to the present embodiment, a very remarkable μ-V positive gradient property is exhibited, the initial characteristics are good, and even when the surface pressure is increased, a remarkable μ-V positive gradient is obtained. The gradient is maintained, and the positive value of the gradient amount is larger than that in the first embodiment. As described above, as is clear by comparing FIG. 2 and FIG. 3, the friction material having a relatively low resin ratio and low density is used for Examples 1 and 2 and Comparative Examples 1 to 6 as well. The result of FIG. 3 was better overall.

  The reason for this is considered to be that the influence of the resin becomes smaller due to the low resin ratio, and the porosity increases due to the low density, and the oil absorbability becomes higher.

  Next, a mechanism for improving friction characteristics in the friction material 1 according to the present embodiment will be described with reference to FIG. In the stage of step S13 in FIG. 1, the inside of the friction material 1 being manufactured has a cross-sectional structure as schematically shown in the upper diagram of FIG. That is, after the thermosetting resin 2 is impregnated into the paper body structure in which the base fiber 3 and the filler 4 are intertwined, the migration is performed in step S12 of FIG. The closer to the surface, the higher the resin concentration.

  Even with the effect of this migration alone, near the surface where the resin concentration is low, the flexibility is improved and the friction characteristics are improved. However, in order to further improve the characteristics, as shown in the upper diagram of FIG. 1 is scraped off by surface polishing as shown in step S14 of FIG. 1, and the base fiber 3 and filler are formed on the friction surface as shown in the lower diagram of FIG. Make 4 appear. The friction material 1 obtained in this way not only has a low resin concentration in the vicinity of the surface but also can reduce the influence of the resin, so that excellent friction characteristics as shown in FIGS. 2 and 3 can be obtained. It is considered a thing.

  Next, how these two-stage processes of migration and surface polishing contribute to the improvement of the friction characteristics of the friction material 1 according to the present embodiment will be described with reference to FIG. .

In the case of the friction material 1 according to the present embodiment, the friction characteristics shown in FIG. 2 (material is high resin ratio / high density) and FIG. 3 (material is low resin ratio / low density) are three. Table 1 shows the results of analyzing the ratio (contribution rate) that the two types of treatments, migration and surface polishing, contribute to each surface pressure at each stage using the method of the experimental design method.

  It should be noted that an asterisk (*) after each numerical value in Table 1 indicates data with higher reliability. As shown in Table 1, in the case of low surface pressure (0.4 MPa), the contribution ratio of migration and material (low resin ratio / low density) is high, and in the case of medium surface pressure (1.0 MPa). On the contrary, the contribution ratio of migration and material becomes low and the contribution ratio of surface friction becomes remarkably high. Furthermore, in the case of high surface pressure (1.4 MPa), the contribution ratio of surface friction becomes higher regardless of the material. ing.

  This is shown in the graph in FIG. As shown in FIG. 5, the contribution ratio of migration and surface polishing changes almost linearly with respect to the surface pressure, and the contribution ratio of migration decreases as the surface pressure increases. Increases as the surface pressure increases. As described above, the contribution ratios of the two types of treatments, migration and surface polishing, have characteristics that are mutually opposite to the surface pressure. As a result, the low surface pressure (0.4 MPa) to the high surface pressure (1.4 MPa). )), The friction material 1 can obtain a remarkable μ-V positive gradient as in Example 1 shown in FIG. 2 and Example 2 shown in FIG.

  In addition, since the amount of resin near the friction surface is small, not only the μ-V positive gradient but also the actual vehicle feeling such as the engagement characteristics is improved. Furthermore, since the amount of the resin on the friction surface is small, the initial characteristics are improved, and this provides the effect that the AT performance is stabilized from the beginning. Here, “in the vicinity of the friction surface” refers to a range from the friction surface to a depth of about 10% with respect to the thickness of the entire friction material in the present embodiment.

  In addition, the friction material manufacturing method according to the present embodiment includes a step of lowering the temperature of the friction surface and increasing the temperature of the anti-friction surface in the drying step of the friction material. Since the resin has the property of moving from the low temperature part to the high temperature part by being dragged by the solvent that moves to the high temperature part and is dried, the distribution of the resin amount in the thickness direction is the lowest in the vicinity of the friction surface. Therefore, it becomes an ultra-high heat-resistant friction material having excellent friction characteristics as described above. In addition, the present production method forms a preferable distribution of the resin amount in the conventional drying process, and can be carried out at a low cost because it is not necessary to add a process.

  Further, as a specific effect in the present embodiment, the resin is dragged and moved to the anti-friction surface side, which is a high-temperature portion, by drying by applying a temperature difference between the friction surface and the anti-friction surface as a migration method. Since the phenomenon is utilized, the distribution of the resin amount in the thickness direction of the friction material becomes continuous, and mechanical stress is not concentrated on a specific portion, so that the strength is not lowered.

  Furthermore, in the present embodiment, as shown in FIG. 4, the distribution of the resin amount of the friction material is continuously changed. In the friction material manufacturing process, two sheets having different resin amounts are used. Alternatively, three or more friction materials are formed, and at least a friction material having a different amount of one or more of them is overlapped by bonding using a binder in a properly dried state before completion of drying, and a plurality of resin amounts It can also be manufactured by integrating friction materials having different diameters.

  In this case, the resin amount distribution of the friction material is discontinuously changed. However, the resin content in the friction material with different resin amounts can be arbitrarily set, and the heat resistance, The heat spot property is remarkably improved, and it becomes a friction material with ultra high heat resistance. Moreover, the distribution of the resin amount in the thickness direction of the friction material can be determined by superposition, and an ultra-high heat resistance friction material can be obtained at any low cost.

  The configuration, components, thickness, shape, quantity, material, size, connection relationship, etc. of the other parts of the friction material, and other steps of the friction material manufacturing method are also limited to the present embodiment. It is not a thing.

FIG. 1 is a flowchart showing an outline of a method for manufacturing a friction material according to an embodiment of the present invention. FIG. 2 is a diagram showing the μ-V positive gradient property as a result of measuring the friction characteristics at different surface pressures in Example 1 of the friction material according to the embodiment of the present invention in comparison with the comparative example. FIG. 3 is a diagram showing the μ-V positive gradient as a result of measuring the friction characteristics at different surface pressures in Example 2 of the friction material according to the embodiment of the present invention, in comparison with the comparative example. FIG. 4 is a schematic diagram showing a mechanism for improving the friction characteristics of the friction material according to the embodiment of the present invention. FIG. 5 is a diagram showing a contribution ratio of the friction material according to the embodiment of the present invention to the surface pressure of the treatment.

Explanation of symbols

1 Friction material 2 Resin 3 Base fiber 4 Filler

Claims (11)

  The distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material is such that the vicinity of the friction surface is formed lower than the portion with the highest resin amount in the thickness direction, and the pole of the friction surface is in air. A friction material having a surface layer polished.   2. The friction material according to claim 1, wherein the resin amount of the friction material is lower by 5% or more on the friction surface side between the friction surface side and the anti-friction surface side.   2. The friction material according to claim 1, wherein a resin amount of the friction material is lower by 5% or more on the friction surface side between the friction surface side and the friction material inside. 3.   The friction material according to any one of claims 1 to 3, wherein the resin amount distribution of the friction material is continuously changed.   The friction material according to any one of claims 1 to 3, wherein a distribution of a resin amount of the friction material is changed discontinuously. Forming the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material such that the vicinity of the friction surface is lower than the portion of the highest resin amount in the thickness direction;
And a step of polishing the extreme surface layer portion of the friction surface in the air.   The step of forming the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material so that the vicinity of the friction surface is lower than the portion of the highest resin amount in the thickness direction, The method for producing a friction material according to claim 6, comprising a step of lowering the temperature of one surface and / or increasing the temperature of the other surface when drying the material.   The step of forming the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material so that the vicinity of the friction surface is lower than the portion of the highest resin amount in the thickness direction, The method according to claim 6, further comprising: a step of drying the two friction materials while overlapping the friction surfaces and then curing at a high temperature while separately or overlapping. A method for manufacturing a friction material.   The step of forming the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material so that the vicinity of the friction surface is lower than the portion of the highest resin amount in the thickness direction is two or more. 7. A friction material having different resin amounts is formed, and at least one friction material having different one or more resin amounts is overlapped and integrated before drying is completed. The manufacturing method of the friction material as described in any one of.   The step of forming the distribution of the resin amount in the thickness direction from the friction surface side to the anti-friction surface side of the friction material so that the vicinity of the friction surface is lower than the portion of the highest resin amount in the thickness direction, When the friction material is dried after additional impregnation of the resin on one side of the surface, the side of the friction material additionally impregnated with the resin is set as the outside, and centrifugal force is applied in the thickness direction at a predetermined temperature condition. The method for producing a friction material according to claim 6, further comprising a drying step. The step of polishing the surface of the extreme surface layer in the air in the friction surface is a resin distribution in the thickness direction from the friction surface side to the anti-friction surface side of the friction material. 11. The method according to claim 6, wherein the step of polishing the friction surface of the friction material by 10 μm ± 5 μm is performed after the step of forming the material to be lower than the amount. Manufacturing method of friction material.

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