JPH0261661B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a clutch friction material, particularly a wet friction material suitable for use in oil. [Prior Art] In automobiles that use an internal combustion engine as the prime mover, a clutch is provided between the prime mover and the transmission. The clutch provides the necessary slip when starting or shifting gears, and it is also necessary to intermittent power when changing gears in a gear transmission. In order to perform these functions,
Friction clutches are widely used. Friction clutches can be 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. The wet type is mainly used as a friction element in automatic transmissions in the form of a wet multi-disc clutch. The friction material for wet multi-plate clutches used to be metal (sintered alloy), but recently paper-based friction materials impregnated with thermosetting resin and hardened have become mainstream. This means that it has good friction characteristics, is lighter, and
This is because it has been proven that it is inexpensive and has sufficient durability. Paper-based friction materials impregnated and cured with thermosetting resin (hereinafter simply referred to as wet friction materials) are made by combining organic fibers such as wood pulp, 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 a phenol resin and then 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-
There are No. 58876 and JP-A No. 59-175639. [Problems to be solved by the invention] Cashew dust used in conventional wet friction materials is made by condensing and polymerizing cashew nut shell liquid with formaldehyde or furfural, etc., adding a curing agent to the mixture, and curing in the presence of acid or alkali. let me,
The hardened lumps are crushed and further refined into particles of 50 μm or more.
Particulate cashew dust (hereinafter referred to as particulate cashew dust) of 300 μm is used. However, the paper base material made by wet paper-making with this particulate cashew dust 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 base material. The shedding of this cashew dust not only causes a deterioration of the working environment, such as contamination of manufacturing equipment and floors, but also causes a decrease in the final dynamic friction coefficient of the wet friction material, which adversely affects the friction properties. Furthermore, particulate cashew dust may fall off from the wet friction material attached to the automatic transmission due to impact during engagement or wear. In this case, the particulate cash dust that falls off becomes huge wear particles that are carried by the oil in the automatic transmission, causing valve sticking. The present invention has been made in view of these points, and it is an object of the present invention to prevent or reduce the falling off 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. . [Means for Solving the Problems] The wet friction material of the present invention comprises a fiber component, a thermosetting resin, and a friction modifier, and the friction modifier has a plurality of protruding diameters of 1 to 50 mm from the surface of cashew dust.
It is characterized by being cashew dust (hereinafter referred to as fiber-containing cashew dust) containing short fibers of 20 μm and 10 to 300 μm in length. A suitable amount of short fibers contained in the cashew dust is 50 to 100 parts by weight per 100 parts by weight of the cashew dust. The fiber components that make up the skeleton of the paper base material include, for example, organic fibers such as wood pulp, linter pulp, aromatic polyamide fibers, and novoloid fibers, glass fibers, potassium titanate fibers, silica fibers, rock wool fibers, and metal fibers. There are inorganic fibers, which can be used alone or in combination of two or more. The appropriate blending ratio of the fiber component 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. 100 parts by weight of the paper base material is impregnated with 20 to 40 parts by weight of the thermosetting resin. In addition, as an inorganic filler, calcium carbonate,
Iron oxide, wollastonite, barium sulfate, silicon oxide, diatomaceous earth, etc. can also be used.
The blending ratio of the inorganic filler is 5 to 40% by weight in the paper base material. The fiber-containing cashew dust used as a friction modifier, which is an important part of this invention, can be obtained by the following manufacturing method. A condensation product is obtained by a known method using cashew nut shell liquid and formaldehyde or furfural as raw materials. This polycondensate has a diameter of 1 to 20 μm and a length of 10
After adding short fibers of ~300 μm and uniformly dispersing them, a cured product such as hexamethylenetetramine is added and cured in the presence of acid or alkali. The cured product is further cooled and pulverized using a pulverizer to obtain fiber-containing cashew dust. In this fiber-containing cashew dust, a rubber component such as natural rubber, chloroprene rubber, or acrylic rubber, a friction modifier other than cashew dust such as graphite, or the above-mentioned inorganic filler can be added and mixed with the condensation product. As the short fibers contained in the cashew dust, the same fibers as the fiber component constituting the skeleton of the paper base material can be used. In particular, fibrillated aromatic polyamide fibers (hereinafter referred to as aramid pulp)
is preferred. To produce a wet friction material, after dispersing the fiber component, fiber-containing cashew dust, and if necessary, an inorganic filler and fixing agent in water, paper is made using a Fourdrinier type or circular wire type paper machine. After drying,
Punch out into the specified shape. Next, the punched paper base material is impregnated with a thermosetting resin and cured in a hot air oven to obtain a wet friction material. [Function] The fiber-containing cashew dust used in the wet friction material of the present invention has a plurality of short fibers protruding from its surface, so that it does not get entangled with the fiber components that make up the skeleton of the paper base material during paper making. It is strong and prevents cashew dust from falling off during the drying process after paper making, the punching process, or during transportation. [Examples] Examples of wet friction materials to which the present invention is applied will be described in detail below. Example 1 Wood pulp 50wt%, aramid pulp 10wt%
After beating in water to a mouth water content of 580 to 620 ml, aramid pulp-containing cashew dust
After sequentially charging 10wt% and 30wt% of diatomaceous earth, dispersing them, and fixing them with a sulfuric acid band, paper is made to a predetermined basis weight and thickness using a circular mesh papermaking machine to obtain a paper base material. This paper base material was punched into a predetermined ring, impregnated with 30 parts by weight of phenol resin per 100 parts by weight of the paper base material by a dipping method, and then heated in a hot air oven.
Cure at 160℃ for 45 minutes. Furthermore, the core bar coated with a thermosetting adhesive is sandwiched, and heated and pressure molded for 2 minutes at 170°C using a thermoforming machine to adjust the thickness to a predetermined thickness to obtain a wet friction material. Example 2 Cashew dust containing aramid pulp 10wt%
Aramid pulp containing cashew dust 20wt%
A wet friction material was obtained in the same manner as in Example 1 except for the following. Comparative example 1 Cashew dust containing aramid pulp 10wt%
A wet friction material was obtained in the same manner as in Example 1, except that the particulate cashew dust was changed to 10 wt%. Comparative example 2 Cashew dust containing aramid pulp 10wt%
Except that the particulate cashew dust was 20wt%.
A wet friction material was obtained in the same manner as in Example 1. The test results of Examples 1 and 2 and Comparative Examples 1 and 2 are
Shown in the table.

[Table] The falling off of cashew dust shown in Table 1 indicates the presence or absence of falling off of cashew dust during the drying process and punching process after the paper making process, where 〇 means almost no falling off, and × means falling off. In addition, the final kinetic friction coefficient was measured using an SAE #2 test machine in an oil liquid at an oil temperature of 120℃.
Moment of inertia = 2.5Kg・cm・sec ² , rotation speed =
This is the friction coefficient when tested for 2000 cycles under the measurement conditions of 3600 rpm and load = 300 kg. The size of wear particles can be determined by measuring the final dynamic friction coefficient.
The oil in the test machine was filtered, the abrasion powder was taken out, and the size was measured by observing the abrasion powder using an electron microscope photograph. [Effects of the Invention] As explained above, the wet friction material of the present invention has the following effects:
Cashew dust does not fall off during the manufacturing process, preventing stains on the manufacturing equipment and floor. Since the cashew dust does not fall off, the final dynamic coefficient of friction does not decrease and the friction characteristics are stable. Also, no large abrasion particles are generated. Since cashew dust does not fall off during the manufacturing process, there is no fluctuation in the blended amount of cashew dust, there is little variation in quality, and it is highly reliable as a wet friction material. Furthermore, there is no material loss and there is an economic advantage.

Claims (1)

[Scope of Claims] 1. A wet friction agent comprising a fiber component, a thermosetting resin, and a friction modifier, in which the friction modifier has a plurality of protruding diameters of 1 to 20 μm from the surface of cashew dust.
A wet friction material characterized in that it is cashew dust containing short fibers with a length of 10 to 300 μm. 2 Short fibers per 100 parts by weight of cashew dust,
The wet friction material according to claim 1, characterized in that the wet friction material contains 50 to 100 parts by weight.