JPS63152735A - Wet type friction material and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a friction material of excellent heat resistance and durability, by overlapping a friction surface side layer, in which a paper quality base material consisting of fiber component, inorganic filling agent and a friction adjusting agent is impregnated with thermo-setting resin, with a fixed surface side layer, in which a paper quality material consisting of fiber component is impregnated with thermo-setting resin, and restricting gas holes in each paper quality base material. CONSTITUTION:Water soluble dispersion fluid 5, mixed with a fiber component, inorganic filling agent and a friction adjusting agent, is allowed to flow on a papermaking net 6, performing papermaking. Water soluble dispersion fluid 8, containing glass fiber and/or pulp, is allowed to flow on roll paper 7 made being not dried, obtaining two layers of paper quality components 10 as a base material performing papermaking. Next, this paper quality component 10 is impregnated with thermo-setting resin being heated and hardened, thus obtaining a wet type friction material 1. Here a friction surface side layer 2 forms its paper quality base material such that its porosity is 50-65% with gas holes of size of 5mu or less occupying 80% the total gas holes. A fixed side surface layer 3 sets each value to 40-70%. In this way, the wet type friction material excellent in durability and heat resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a friction material for a clutch, particularly a wet type ItI! suitable for use in an oil solution. This article relates to rubbing materials and methods of manufacturing them.

[Conventional technology]

For example, the clutch that transmits the drive from the prime mover to the transmission in automobiles, construction machinery, agricultural machinery, motor boats, etc.
While sufficient power is transmitted at all times, a function is required to provide adequate slippage during a first start, and to cut off power when the gears of the transmission shift. L as a clutch that fulfills these functions! 9! Friction type clutches are widely used. Friction type clutches include dry clutches that are used in dry conditions and wet clutches that are used in oil. The latter wet type clutch is often used in the form of a multi-disc clutch as a 411 component in a planetary gear type automatic transmission.

Friction-type clutches generate frictional heat, so friction is required for the above-mentioned machine parts to function stably. In wet clutches, where heat must be efficiently released from parts, oil plays an important role as a heat transport medium. The heat generated on the friction surface is diffused and released throughout the system using oil as a medium. Therefore, if the amount of oil held in the friction material itself and the amount of oil flowing in and out are small, it will overheat, causing thermal deterioration of the friction material and oxidation and decomposition of the oil, resulting in a decrease in its agility as a friction material.

Wet friction materials are made by impregnating thermosetting resins such as phenolic resins and melamine resins onto paper base materials that are wet-printed with organic fibers, inorganic fibers, inorganic powder fillers, and friction modifiers such as cashew dust. be. It is thought that oil is retained and circulated in the pores of this paper base material.

A conventional friction material is disclosed in, for example, Japanese Patent Laid-Open No. 80-23774.

[Problem that the invention seeks to solve]

In conventional wet friction materials, research has focused on the types and composition ratios of raw materials, and the pores (the areas where oil is retained) have not necessarily been sufficiently studied. Therefore, while the structure of the paper base material from which paper was made aggregated, the individual pores tended to become larger.
If the structure of the paper base material is aggregated, friction materials impregnated with thermosetting resin will not circulate or retain oil in the aggregated areas, resulting in insufficient cooling and poor heat resistance. turn into.

In addition, asbestos, which was once thought to be an excellent raw material for friction materials and was frequently used, has been found to be harmful to health, making it difficult to use. It's getting narrower. Therefore, a friction material that has sufficient performance but is not harmful in terms of IP stability has not been obtained.

The present invention has been made in view of these points, and it is an object of the present invention to provide a friction material that is excellent in heat resistance and friction performance and does not contain harmful substances at a low cost.

[Means for solving problems]

The present inventors have focused on the fact that the performance of a wet friction material is influenced by the retention and circulation of oil in the pores, and as a result of continued research, they have completed the present invention. That is, the wet friction material 1 of the present invention has two layers, a layer 2 on the friction surface side and a layer 3 on the fixed surface side, as shown in FIG. 1 (cross-sectional view). Layer 2 on the friction surface side is made of a paper base material made by wet paper-making of a fiber component constituting a skeleton, an inorganic filler, and a friction modifier, and impregnated with a thermosetting resin, and the paper base material has a porosity of 50. ~65%, and pores with a pore diameter of 5 microns or less account for 80% or more of all pores.

The layer 3 on the fixed surface side has a porosity of 40 to 70%, and pores with a pore diameter of 5 microns or more account for 60% or more of the total pores.

The layer 2 on the friction surface side contains, for example, 10 to 50% by weight of fibrid fibers as at least part of the fiber m component, the particle size of the inorganic filler is 5 microns or less, and the particle size of the friction modifier is 50 microns or less. is preferable, and the layer 3 on the fixed surface side contains a fiber component, for example glass fiber or pulp, or both.

Fibrid fibers are fibers made of, for example, cellulose fibers, aromatic polyamide fibers, etc., which have been miniaturized to a thickness of 0.2 to 2 microns, and have the property of being fibrillated by wet paper forming. In addition to the above-mentioned fibrid fibers, for example, novoloid mta, glass fibers, rock wool, ceramic fibers, and metal fibers may be partially mixed into the layer 2 on the friction surface side as fiber components.

Examples of inorganic fillers include diatom and alumina powder.

These are barium sulfate, calcium carbonate, and silica.

Friction modifiers include, for example, graphite and cashew dust.

The method for manufacturing the wet friction material 1 of the present invention is, for example, as shown in FIG. A two-layer paper component 10 is used as a base material by pouring it onto a screen 6 to make paper, and pouring an aqueous dispersion 8 containing glass fiber or (and) pulp onto an undried paper web 7 to make paper. It is characterized by

[Function] In the wet friction material of the present invention, the pores in the layer 2 on the friction surface side become minute and dispersed due to the action of the above-mentioned raw materials, especially the action of the fibrid fibers. When the porosity is less than 50%, oil retention and circulation are insufficient, and when the porosity is 65%, the mechanical strength of the friction material itself is insufficient. In contrast, the friction material of the present invention has a porosity of 40 to 75%, and moreover, 80% or more of the pores are pores of 5 microns or less.

Therefore, since the oil circulates through the dispersed fine pores, cooling performance is improved.

Furthermore, since the layer 3 on the fixed surface side has a relatively large pore diameter, oil absorption and dissipation are good, and oil from the layer 2 side on the friction surface is well circulated. Therefore, cooling performance is further improved.

Moreover, since the layer 2 on the friction surface side and the layer 3 on the fixed surface side are made into paper continuously, they are integrated and have high mechanical strength.

〔Example〕

Examples of the present invention will be described in detail below.

Paper is made using each raw material shown in Table 1 (composition table) below to obtain a paper base material. Examples 1 to 5 are examples of wet friction materials to which the present invention is applied, and Comparative Examples 6 to 8 are examples in which the present invention is not suitable.

(The following is a margin) Table 1: Mixed weight % As shown in Table 2, paper is made using a fourdrinier paper machine. First, the aqueous dispersion 5 of each raw material constituting the layer 2 on the friction surface side flows onto the endless fourdrinier 6, and the fibers of the paper web 7 are dispersed and removed.During the water removal, they are fixed. The aqueous dispersion 8 of each raw material constituting the surface side M3 flows onto the paper web 7, forming a two-layer paper component 10. The two-layer paper component 10 is compressed by press rolls 16, 16, dried by drying drums 17 and 18, and then wound onto a roll 19. Note that 12 is a dandy roll, 1371 table roll, and 14 is a suction box. As shown in FIG. 3, the roll-shaped paper component IO is cut by a cutter 20 into a sheet. A wet friction material 1 is produced by impregnating this paper component 10 with a phenol resin in the weight ratio shown in the formulation table by spraying and curing by heating. This wet type friction material 1 is cut into a disk shape as shown in FIG. 4, and is adhered to both sides of the core metal 22 as shown in FIG. 5 to complete the friction plate of the wet type clutch. In the example shown in FIG. 5, grooves are provided on the surface of the friction material l, that is, the cross section is the sixth
The result will be as shown in the figure. The layer 2 on the friction surface side comes into contact with a disc rotor 23 (indicated by a chain line).

The porosity and pore diameter distribution of each wet friction material are measured using a porosimeter (porosity measuring meter manufactured by Shimadzu Corporation). The pore size distribution is measured by applying pressure to a sample (friction material) and filling it with viscous fluid. At the beginning of pressurization, large pores are filled, but as the pressure increases, smaller pores are filled, so the relationship between pressure and filling amount can be measured. That is, since the filling amount is filled starting with the pores having a larger diameter as the pressure changes, by differentiating the relationship between the pressure and the filling amount, the pore diameter and the pore amount at that pore diameter can be determined.

FIG. 7 is a curve of the distribution of the amount of pores (pore diameter distribution) with respect to the pore diameter of the groove 2 on the friction surface side. The curves ■ to ■ shown by solid lines are the pore size distributions of the friction materials of Examples 1 to 5 and Comparative Example 6, when the porosity is 55 to 58% and the pore amount is at its peak (at the maximum in the illustrated curve). ) has a pore diameter of 2.5 microns
It is. The curve (■) shown by the chain line is the pore size distribution of the friction material of Comparative Example 7, and the pore size when the porosity is 55% and the pore amount reaches its peak! The curve ■ shown by the 0 dotted line, which is 0 micron m, is the pore size distribution of the friction material of Comparative Example 8, and the porosity is 56.
%, the pore diameter when the pore volume reaches its peak is 7 microns.
It is.

FIG. 8 is a curve of the pore size distribution of the layer 3 on the fixed surface side. The solid curve ■■ represents the pore size distribution of the friction materials of Example 1 and Example 2, and the porosity is 60%. The ■■ curve shown by the chain line is the pore size distribution of the friction materials of Example 3 and Example 4, and the ■■ curve shown by the 0-dot line with a porosity of 63% is the pore size distribution of the friction material of Example 5. Distribution, porosity is 56%
It is. The pore diameter when the pore volume reaches its peak in each individual is
Each is about 10 microns or more. Note that Comparative Example 6 does not have a layer on the fixed side, and the layers on the fixed side of Comparative Examples 7 and 8 are the same as the layers on the fixed side of Examples 1 and 2, so the pore size distribution is the same as the curve shown by the solid line.

Also, the coefficient of friction (pd) for each wet friction material.

Measure durability and heat resistance. The test piece used is one obtained by cutting each of the above wet friction materials into a predetermined size, and pasting the cut pieces with a metal center plate in between.

! ! To measure the friction coefficient, a load is applied to the friction material rotating inertia using an SAE #2 friction tester, and the friction coefficient is calculated from the torque.

Measurement conditions Number of friction surfaces: 4, inertia: 2.5Kg-cm・5e
c2° rotation speed: 380Orpm, surface pressure: 7.2K
g/cm2, in oil liquid, oil temperature: 120°C, and the results of measuring each friction coefficient are shown in FIG.

The coefficient of friction (pd) shown in the figure is the value at 100 to 2000 cycles, and the coefficient of friction is approximately stable during these cycles. The friction materials of Examples 1 to 5 and the friction materials of Comparative Examples 6 to 8 have approximately the same coefficient of friction (ru d).

How much difference can be made in durability depending on the diameter of the pores in layer 2 on the friction surface side? ) and Comparative Example 8 (peak pore diameter 7 μm). Measuring durability is the same as measuring friction coefficient <1 constant using SAE #2 friction tester (q,
m25cal/cm2), until the coefficient of friction (#Ld) drops by 10% from the initial stable state, or until the peeling reaches lθ
The load cycle until % occurs is shown in Fig. 1θ. As shown in the figure, it can be seen that the smaller the peak pore diameter of the layer 2 on the friction surface side, the better the durability.

Heat resistance is measured under the following measurement conditions.

Measurement conditions Number of friction surfaces: 6. Inertia: 2.0Kg-cm・5e
c2, rotation speed: 3000 to 8200 rpm, adjusted so that the load braking time is 15ec, oil liquid: flow Q 2.
5cc/cm2-sin sea? 7 pieces were blown out, (q,
= 10~45caJl/cm2), oil temperature 280
C. The measurement results of heat resistance are shown in Table 2 below.

Judgment of heat resistance is based on the coefficient of friction (ILd) at initial stability of 9.
A period up to 10% drop or until peeling occurs is considered good.

Table 2 Heat resistance A: Good up to 5000 cycles B: Good up to 2000 cycles C: Good up to 100 cycles D: Good up to 100 cycles E: Waveform distortion As shown in Table 2, the friction materials of Examples 1 to 5 , the heat resistance is improved compared to the 1tI rubbing materials of Comparative Examples 6 to 8.

In addition, the above example uses a fourdrinier paper making machine to produce paper material lO
However, it is also possible to manufacture using a circular mesh paper machine.

[Effects of IJ1] As explained above, the wet friction material of the present invention has improved cooling properties, and therefore has excellent heat resistance and friction performance. Even when used in conventional locations, durability and heat resistance can be improved without changing the friction coefficient level. Furthermore, it does not contain asbestos, which is harmful to health.

Furthermore, since the friction surface side layer and the fixed surface side layer are made into paper continuously, they are integrated, resulting in high mechanical strength and a simple manufacturing process.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a wet friction material to which the present invention is applied, Fig. 2 is a schematic configuration diagram showing an embodiment of an apparatus for manufacturing a wet friction material, and Fig. 4 of Fig. 3 shows the manufacturing process of a wet friction material. Figure 5 is an exploded perspective view of the friction plate; Figure 6 is a sectional view showing the relationship between the wet friction material and the disc rotor; Figure 7 is a diagram showing the pore size distribution of the layer on the friction surface side; FIG. 8 is a diagram showing the pore size distribution of the layer on the fixed surface side, FIG. 9 is a diagram showing the friction coefficient, and FIG. 10 is a diagram showing the change in durability depending on the pore diameter. 1. Wet friction material 2. Layer on friction surface side 3. Layer on fixed surface side 6. Endless fourdrinier 7.
... Paperfish 5.8 ... Aqueous dispersion io,
,,,Paper quality component 19. ,,,,roll 20-...
Cutter 22...Core 23...Disc rotor Patent applicant Aisin Kako Co., Ltd. Toyota Motor Corporation Figure 10 Pore column 1: J: 5 resistance ~ Figure 9←--Tora Example - Example Tor ratio battle example → 7th v4 Layer on the emotional side Figure 8 Layer on the fixed side

Claims (1)

[Claims] 1. It has two layers: a layer on the friction surface side and a layer on the fixed surface side, and the layer on the friction surface side contains a fiber component constituting the skeleton, an inorganic filler, and a friction modifier. A paper base material made by wet papermaking is impregnated with a thermosetting resin, and the paper base material has a porosity of 50 to 65%, pores with a pore diameter of 5 microns or less account for 80% or more of the total pores, and are fixed. The surface layer is made of a paper base material made by wet papermaking of the fiber components that make up the skeleton, and is impregnated with a thermosetting resin.
A wet friction material characterized in that pores with a porosity of 40 to 70% and a pore diameter of 5 microns or more account for 60% or more of all pores. 2. The layer on the friction surface side contains 10 to 50% by weight of fibrid fibers as at least part of the fiber component, and the particle size of the inorganic filler is 5 microns or less and the particle size of the friction modifier is 50 microns or less. The wet friction material according to claim 1, wherein the layer on the fixed surface side contains glass fiber and/or pulp as a fiber component. 3. Paper is made by pouring an aqueous dispersion of a fiber component containing at least a portion of fibrid fibers, an inorganic filler, and a friction modifier onto a papermaking net, and glass fibers or A method for producing a wet friction material, characterized in that the base material is a two-layer paper component made by flowing an aqueous dispersion containing / and pulp.