JPS6366232A - Wet friction material - Google Patents

Abstract

PURPOSE:To obtain the title friction material, by blending a fibrous component with thermosetting resin and friction modifying agent consisting of specific cashew dust, capable of sustaining good final friction coefficient without falling off the above-mentioned dust in production, having uniform quality and suitable for use in oil. CONSTITUTION:A wet friction material obtained by blending a fibrous component with thermosetting resin and cashew dust prepared by pulverizing an expanded and cured article to a size of 50-300mum as a friction modifying agent. Wood pulp, silica, etc., are be used as the fibrous component and a material prepared by expanding and curing a polycondensate of cashew nutshell liquid with formaldehyde, etc., are be used as the friction modifying agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a friction material for a clutch, particularly a wet friction material suitable for use in oil.

[Prior Art] In automobiles that use an internal combustion engine as a prime mover, a clutch is provided between the prime mover and the transmission. The clutch provides the necessary slip when starting or changing gears, and it is also necessary to connect and disconnect power when changing gears in the gear transmission. Friction clutches are widely used to provide these functions.

Friction clutches are divided into dry types, in which the friction plates are used in a dry state, and wet types, in which the friction plates are immersed in oil. Wet type is mainly used as a friction element in automatic transmissions in the form of wet multi-disc clutches.

The friction material for wet multi-disc clutches used to be metal (sintered metal), but recently paper-based friction materials impregnated with thermosetting resin and hardened have become mainstream.

This is because it has been proven that it has good friction properties, is lightweight, inexpensive, and has sufficient durability.

A paper-based friction material impregnated and cured with a thermosetting resin (hereinafter simply referred to as a wet friction material) is a combination of organic fibers such as wood valves, inorganic fibers such as asbestos, inorganic fillers, and friction modifiers. A paper base material made by wet papermaking is impregnated with a thermosetting resin such as phenol resin and compression molded.

Cashew dust is used as a friction modifier in wet friction materials to adjust the friction coefficient (especially the final dynamic friction coefficient). For example, JP-A-57-85876, JP-A-59
There is No.-175639.

[Problems to be solved by the invention] Cashew dust, which is used in conventional wet friction materials, is made by condensing cashew nut shell liquid with formaldehyde or furfural, etc., adding a curing agent to the mixture, and then processing it in the presence of an acid or alkali. This hardened lump is pulverized and finely granulated to obtain particulate cashew dust (hereinafter referred to as particulate cashew dust) having a size of 50 μm to 300 μm. However, this particulate cashew dust is blended with I
The paper Sogetsu that is wet-paper-made is subjected to various forces during the drying process, punching process into a predetermined mold, or transportation, and the particulate cashew dust falls off from the paper Sogetsu. This shedding of cashew dust not only causes a deterioration of the working environment, such as contamination of manufacturing equipment and floors, but also lowers the final kinetic friction coefficient of the paper friction material, adversely affecting the friction characteristics.

Further, particulate cashew dust may sometimes fall off from a wet friction material that is not attached to an automatic transmission due to impact during engagement or wear. In this case, the fallen particulate cashew dust becomes huge abrasion powder and is transported by the oil in the automatic transmission.
This can cause valve stick.

The present invention was made in view of these points, and it is an object of the present invention to prevent or reduce the shedding of cashew dust, which is a friction modifier, from a paper base material or a wet friction material, and to provide a wet friction material with stable friction characteristics. be.

[Means for solving the problems] That is, the wet friction agent of the present invention has a fiber component, thermosetting + I
[Composed of a resin and a friction modifier, after this friction modifier is foamed and cured, the cured product is heated to a thickness of 50 μm to 300 μm.
It is characterized by being made of cashew dust (hereinafter referred to as F-foamed cashew dust) that has been crushed to a size of .

The fiber components that make up the paper skeleton include, for example, wood bulbs, linter pulp, aromatic polyamide fibers, organic fibers such as novoloid fibers, glass fibers, potassium titanate mi, and silica! Inorganic M such as a fiber, rock wool fiber, metal fiber, etc. It has fibers and is used either alone or as a mixture of two or more types. An appropriate blending ratio of miscellaneous components is 40 to 75% by weight in the paper base material.

As the thermosetting resin, for example, phenol resin, melamine resin, epoxy resin, polyester resin, etc. can be used.

The thermosetting resin is 2 parts per 10011'j parts of the paper base material.
Impregnate 0 to 40 parts by weight.

Furthermore, as inorganic fillers, calcium carbonate, iron oxide,
Wollastonite, barium sulfate, silicon oxide, diaphragm, etc. can also be used.

The blending ratio of the inorganic filler is 5 to 40% by weight in the paper base material.
It is.

The foamed cashew dust used as a friction modifier, which is a key part of this invention, is produced by adding a foaming agent and a hardening agent to a condensation product of cashew nut shell liquid and formaldehyde or furfural, etc., and then heating the powder at 80°C to 80°C in the presence of an acid or alkali. 2
The curing reaction proceeds while foaming at a heating temperature of 10°C.

After being cooled and solidified, it is pulverized to 50 μm to 300 μm using a pulverizer.

A rubber component such as natural rubber, chloroprene rubber, or acrylic rubber, a friction adjuster such as graphite other than cashew dust, or the above-mentioned inorganic filler may be added and mixed to the condensation product before foaming and curing. .

Examples of blowing agents include liquid blowing agents such as heptane and hexane, and dinitrosopentamethylenetetramine (DPT).
) type, azodicarbonamide (AZC) type, and P-toluenesulfonylhydrazide (TSH) type solid foaming agents can be used.

Moreover, a urea-based foaming aid can be used in combination.

As a hardening agent, a formaldehyde source such as paraformaldehyde or hexamethylenetetramine can be used.

A suitable blending ratio of the friction modifier is 5 to 40% by weight in the paper base material.

To manufacture wet friction materials! After dispersing fine components, a friction material modifier, and, if necessary, inorganic fillers and fixing agents in water, paper is made using a paper machine, dried, and punched into a predetermined mold. Next, a wet friction material is obtained by impregnating the punched paper base material with a thermosetting resin and curing it in a hot air oven or the like.

[Function] The foamed cashew dust used in the wet friction material of the present invention is
By foaming during curing, this cured product has many air bubbles like a sponge. The foamed cashew dust obtained by crushing this hardened product has sharper edges than conventional particulate cashew dust, and contains a lot of thin, scaly cashew dust, so it is difficult to get entangled with fiber components during paper making. This strongly prevents cashew dust from falling off during the subsequent drying process, punching process, or transportation.

[Examples] Examples of wet friction materials to which the present invention is applied will be described in detail below.

[Example 1] Rinta Halb 50 wt! 6. Glass m fiber 10wt!
ji After beating in whole water to a mouth water content of 580 to 620 mfi, foamed cashew dust 10 wtJ,
After 30wt'J of diatomaceous earth was sequentially charged, dispersed, and fixed with a sulfuric acid band, paper was made to a predetermined basis weight and thickness using a circular mesh papermaking machine to obtain a paper base material. This paper base material is punched into a predetermined ring, and the phenol resin is applied to the paper base material 1.
30 parts by weight per 00 parts by weight is impregnated by a dipping method, and heated and pressure molded in a hot air oven at 160° C. for 45 minutes to adjust to a predetermined thickness to obtain a wet friction material.

[Example 2] Foamed cashew dust 10wt! A wet friction material is obtained in the same manner as in Example 1 except that ji is 20 wt of foamed cashew dust and zero.

[Comparative Example 1] A wet friction material was obtained in the same manner as in Example 1, except that 10 wt% of foamed cashew dust was replaced with 10 wt% of particulate cashew dust.

[Comparative Example 2] A wet friction material was obtained in the same manner as in Example 2, except that 10 wt'J of foamed cashew dust was changed to 20 wt% of particulate cashew dust.

The test results of Example 1.2 and Comparative Example 1.2 are shown in Table 1.

Table 1 The shedding of cashew dust shown in Table 1 indicates the presence or absence of shedding of cashew dust during the drying process and punching process after the papermaking process, where ○ means almost no shedding and × means there is some shedding.

In addition, the final dynamic friction coefficient was determined using an SAE #2 test machine at an oil temperature of 12.
Moment of inertia in oil liquid at 0℃ = 2.5kg-cm-8
eC2, rotation speed = 3600 rpm, load = 300
This is the friction coefficient when tested for 2000 cycles under the measurement conditions of Kg.

After measuring the final dynamic friction coefficient, the size of the wear powder was determined by filtering the oil in the test machine, taking out the wear powder, and observing the wear powder using an electron microscope photograph.

[Effects of the Invention] As explained above, the wet friction material of the present invention prevents cashew dust from falling off during the manufacturing process, and prevents staining of the manufacturing equipment and floor. Since the cashew dust does not fall off, the final friction coefficient does not decrease and the friction characteristics are stable. Also, no large wear particles are generated. Since cashew dust does not fall off during the manufacturing process, there is no change in the blending ratio of cashew dust, resulting in less variation in quality and high reliability as a friction material. Furthermore, there is no loss of materials and there is an economical advantage.

Claims (1)

[Claims] (1) In a wet friction material consisting of a fiber component, a thermosetting resin, and a friction modifier, the friction modifier is foamed and cured, and then the cured product is pulverized to a size of 50 μm to 300 μm. Cashew dust A wet friction material characterized by comprising: