JPH04363384A - Wet type frictional material - Google Patents

Abstract

PURPOSE:To obtain a wet type frictional material usable in oils, having improved heat resistance, dynamic frictional characteristics and long-term stability, comprising a base, a friction adjuster, an inorganic filler containing a specific amount of a lipophilic porous inorganic material and a resin. CONSTITUTION:(A) A base composed of organic fibers and inorganic fibers is blended with (B) a friction adjuster composed of Al powder or rubber powder, (C) an inorganic filler containing 10-20wt.% based on 100wt.% of the components A-C of a lipophilic porous inorganic material having preferably 6-40mum particle diameter obtained by grinding perlite or pitchstone and (D) a resin such as phenol resin or epoxy resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wet friction material that is used in oil and has particularly improved heat resistance and dynamic friction characteristics.

[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. This clutch provides the necessary slip when starting or shifting gears, and it is also necessary to connect and disconnect power when changing gears after shifting the gear transmission. Friction clutches are widely used to fulfill these functions.

Friction clutches can be divided into dry friction plates that are used in a dry state and wet friction plates that are used immersed in oil.

Friction materials used in wet friction plates used to be sintered alloys, but recently paper-based friction materials impregnated with thermosetting resin and hardened have become mainstream. This type of friction material is made by wet-forming a fiber base material of organic fibers, inorganic fibers, inorganic fillers, and friction modifiers, impregnating it with thermosetting resin such as phenol resin, drying, and compression molding. . (For example, JP-A-57-85876, JP-A-59-175639) [
[Problems to be solved by the invention] In recent years, as automobile engines have become faster and more powerful,
Wet friction materials inside automatic transmissions are now required to have a high friction coefficient and high heat resistance.

The improvement of the dynamic friction coefficient and heat resistance of wet friction materials is related to the material's aggressive effect and oil retention ability, and this can be countered by improving the entanglement property of the base material by fibrillating and making it finer. As additives, carbon, iron, copper, and other metals are effective in improving thermal conductivity. As the inorganic additive, diatomaceous earth is mainly used. This diatomaceous earth is naturally produced, and its particle size is 0. It has a cylindrical shape ranging from several microns to several hundred microns. For this reason, mixing with the resin during molding tends to be incomplete, and the fixing rate during paper making is inconsistent. Also, although this diatomaceous earth is porous,
Among the pores, the effective pore diameter is only about 40% of the total pores. Therefore, there are limits to the oil retention, absorption, and conformability of wet friction materials in oil, and there are problems with heat resistance and durability. An object of the present invention is to provide a wet friction material that solves the above problems by improving the permeability of oil such as inorganic additives.

[Means for Solving the Problems] The present invention provides a wet friction material obtained by molding a mixed material consisting of a base material, a friction modifier, an inorganic additive, and a resin, in which at least a portion of the inorganic additive is is a lipophilic porous inorganic material, and the lipophilic porous inorganic material has a content of 10 to 10% when the total weight of other components excluding the resin component is 100% by weight.
It is characterized by being 20% by weight.

For the base material of the wet friction material of the present invention, both organic fibers and inorganic fibers can be used. As the organic fiber, one type or a mixture of multiple types of linta pulp, wood pulp, synthetic pulp, polyester fiber, acrylic fiber, polyamide fiber, polyvinyl alcohol modified fiber, polyvinyl chloride fiber, polypropylene fiber, carbon fiber, etc. is used. be able to. Inorganic fibers include potassium titanate fiber, glass fiber, kaolin fiber, silica fiber,
One or more types of bauxite fibers, kyanoid fibers, boron fibers, magnesia fibers, rock wool fibers, metal fibers, etc. can be used. Note that it is effective to use organic fiber as the main material for weight reduction.

The friction modifier is used to improve and stabilize the coefficient of friction, and includes, for example, metal powder such as aluminum powder, copper powder, and iron powder, rubber powder, cashew dust, and graphite powder.

The greatest feature of the present invention is that a lipophilic porous inorganic material is used as the inorganic additive. The composition of this lipophilic porous inorganic material is as follows: 75% or more of SiO2 and other components such as Al2O3, Fe2O3, CaO, K2O, Na2
It is composed of O, etc.

The specific manufacturing method is to crush pearlite or pinestone to a certain particle size, rapidly heat and expand it, and form airtight small bubbles while being treated to make it lipophilic. Another feature of this material is that each particle is made up of highly irregularly shaped strips, which enhances the aggressive effect. And the particle size is 6~40μ
Preferably, m. Furthermore, the particle size is 6 to 40 μm.
distribution within the range of oil compatibility, retention,
Gives good results in terms of absorbency, etc. If the amount of the lipophilic porous inorganic material is less than 10%, oil adhesion and absorption properties will deteriorate, and if it exceeds 20% by weight, peeling resistance will deteriorate, which is not preferable.

Inorganic additives may include conventionally used silica, talc, magnesium oxide, kaolin, barium sulfate, potassium phosphate, calcium carbonate, diatomaceous earth, etc. in addition to the lipophilic porous inorganic materials mentioned above. can.

The resin binds additives, and as in the past, phenol resin, epoxy resin, melamine resin, urea resin, etc. are used.

To produce the wet friction material of the present invention, a fiber component as a base material, a friction modifier, an inorganic additive, and, if necessary, a fixing agent are dispersed in water, and then paper is made using a paper making machine.
After drying, punch out into the specified shape. Next, the punched base material is impregnated with a phenolic resin, dried, and then heated and press-molded to obtain a wet friction material.

[Operations and Effects of the Invention] The wet friction material of the present invention uses a lipophilic porous inorganic material as at least a part of the inorganic additive, thereby improving oil compatibility, absorbability, and retention. Since this lipophilic porous inorganic material is irregularly shaped strips, it has a high aggressive effect, is heat resistant, and has a high friction coefficient, making it possible to stabilize the friction coefficient over a long period of time. .

[Example] Examples of the present invention will be shown below, but the present invention is not limited thereto.

(Example) 45% by weight of linter pulp, 5% by weight of glass fiber, and 10% by weight of aramid fiber were added to water with a water content of 480 to 520 ml.
After beating to give 15% by weight of cashew resin, 15% by weight of lipophilic porous inorganic material (ROCABELB #4209 [Mitsui Kinzoku Mining Co., Ltd.]), and 10% by weight of diatomaceous earth.
After sequentially charging, dispersing, and fixing with a sulfuric acid band, paper is made to a predetermined weight and thickness using a circular mesh paper making machine. This paper-made base material is punched into predetermined links, and 28 parts by weight of phenolic resin is impregnated with 100 parts by weight of the paper-made base material by a dipping method, and the metal plate is formed at the same time as heat and pressure molding at 170°C for 2 minutes. A wet friction material was obtained by adhering to a disc plate.

(Comparative example) Diatomaceous earth alone was used instead of the lipophilic porous inorganic material.
A wet friction material was obtained in the same manner as in the example except that the weight % was used.

(Evaluation) Wet friction materials obtained in Examples and Comparative Examples were evaluated as SAE No. 2.
A friction test was conducted using a tester for up to 5,000 cycles.

The test conditions are: Inertia: 2.5kgcm・sec2 Surface pressure: 8.4Kg/cm2 Rotation speed: 3600rpm ATF: Toyota Auto Fluid Type T test oil temperature: 12
The test results are shown in FIG. 1 at 0°C.

As shown in FIG. 1, the comparative example was about 7.
While the dynamic friction coefficient decreased by 6%, in the example, the decrease was approximately 2.7%, which is less than half the decrease, indicating that long-term stabilization of the dynamic friction coefficient is achieved.

Patent applicant: Aisin Kako Co., Ltd. Representative Haruo Miyaji 5. Contents of correction After the last line of page 6 of the specification,

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the results of my personal opinion on friction between Examples and Comparative Examples. ” is inserted.

Claims (2)

[Claims] 1. A wet friction material obtained by forming a mixed material comprising a base material, a friction modifier, an inorganic additive, and a resin, wherein at least a part of the inorganic additive is a lipophilic porous inorganic material. Moreover, the lipophilic porous inorganic material has a content of 10 to 20% by weight when the total weight of other components excluding the resin component is 100% by weight.
Wet friction agent characterized in that it is % by weight. 2. The wet friction material according to claim 1, wherein the lipophilic porous inorganic material has a particle size of 6 to 40 μm obtained by crushing and treating pearlite or pinestone.