JPH05320372A - Resin composition for frictional material - Google Patents

Abstract

PURPOSE:To provide a resin composition for frictional material stable to heat and low in squeakiness. CONSTITUTION:The composition consisting mainly of (A) a phenolic resin, (B) an NBR with a bound acrylonitrile content of >=35wt.%, and (C) >=20wt.% of metallic fibers with the weight ratio A/B of 2 to 5, also containing (D) a chloride of a group IIa element at 2-15wt.% based on the component A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for friction materials, and more specifically, it is based on metal fibers, inorganic fibers and organic fibers used as parts for automobiles, railway vehicles, industrial machines and the like. It relates to friction materials.

[0002]

2. Description of the Related Art Friction materials are used for braking automobiles, railway vehicles and industrial machines. This friction material uses phenol resin and rubber as a binder, and uses metal fibers, inorganic fibers such as asbestos and ceramic fibers, and organic fibers such as polyimide, polyamide, and phenol resin as a base material. It is made of a composite material containing fillers and additives as a lubricant. The characteristics required of this friction material include the coefficient of friction, the amount of wear, the aggressiveness to the mating metal plate, the friction performance such as squeal, and the bending strength and the shear strength. With the recent increase in speed of transportation and the increase in size of vehicles, friction materials have come to be used under more severe conditions such as high speed and high load, and have a stable braking effect even under these conditions. Is strongly required. Further, it is said that the factor that most affects the friction performance is the selection of the binder.
A thermosetting resin is widely used as this binder, and a phenol resin is generally used because of its heat resistance, abrasion resistance, price, and the like. As the phenol resin, various modified resins such as cash-modified phenol resin, oil-modified phenol resin, rubber-modified phenol resin and melamine-modified phenol resin, which are excellent in flexibility, have been studied in order to improve the above-mentioned various performances.

[0003]

However, since these are inferior in heat resistance, the braking performance is unstable and squeal occurs when used under severe conditions. The present invention relates to a friction material which does not have the above-mentioned drawbacks, which comprises a phenol resin and NBR having a bound acrylonitrile amount of 35% or more as a main binder, and further contains a chloride of a group IIa element of the periodic table. To do.

[0004]

The present invention will be specifically described below. Examples of the unmodified type of the phenol resin include novolac type phenol resin, resol type phenol resin, and dimethylene ether type phenol resin. Also, there are modified resins such as elastomer modified, cache modified, silicone modified, oil modified, but unmodified novolac type phenolic resin with excellent heat resistance is often used.
It is desirable that the amount of unreacted phenol is 3% by weight or less, preferably 2% by weight or less. When the amount of unreacted phenol is 3% by weight or more, a large amount of low molecular weight substances remain in the hardened friction material.
Under severe conditions, the friction coefficient becomes unstable and stable braking performance cannot be obtained. The ortho ratio is preferably 50% or more, and more preferably 60% or more. If the ortho ratio is low, the cured resin becomes hard, resulting in poor flexibility and poor squealing. If the ortho ratio is 50% or less, the curing reaction is slow, so
If the molding time is not made sufficiently long, the cured state of the resin in the friction material becomes non-uniform, and stable friction coefficient and wear rate cannot be obtained, and also stable braking performance cannot be obtained under severe conditions.

As a method of obtaining such a resin, there is a method of reacting phenols such as carboxylic acid, cresol, xylenol, and alkylphenol with aldehydes such as formaldehyde in the presence of a catalyst such as zinc chloride or zinc acetate. Hexamethylenetetramine as a curing agent is added in an amount of 5% by weight or more and 12% by weight or more based on the phenol resin.
The following is desirable. If the amount added is less than 5% by weight, the crosslink density is too low, and the desired shear strength and bending strength cannot be obtained. On the other hand, if it is 12% by weight or more, unreacted hexamethylenetetramine remains, and the friction coefficient becomes unstable. NBR
It is desirable that the amount of bound acrylonitrile is 35% or more, preferably solid powder.

The chlorides of Group IIa elements of the periodic table are as follows:
There are chlorides such as magnesium, calcium, barium and strontium. Among these, calcium chloride, magnesium chloride, barium chloride and strontium chloride are preferable. Further, the addition amount is preferably 2% by weight to 15% by weight with respect to the phenol resin.

The base material includes metal fibers such as iron, copper and brass and asbestos fibers, ceramic fibers, glass fibers, wollastonite, inorganic fibers such as artificial mineral fibers, polyimide fibers, polyamide fibers and phenol fibers. There are organic fibers. Metal fibers are desirable among these substrates. Further, asbestos fibers cannot be used as other base materials due to the occurrence of pollution, but conventionally used base materials such as inorganic fibers or organic fibers can be used in combination. Further, as the metal fibers, copper fibers and brass fibers which do not cause a problem of rust are desirable. Also, conventionally used inorganic additives such as silica and other lubricants, graphite, antimony trisulfide, molybdenum disulfide and other lubricants, and organic additives such as cache resins can be used alone or in combination. The above composition is uniformly mixed with a Nauta mixer or the like to obtain a molding powder. Molding temperature 130 ℃ to 1
Molding is performed for a predetermined time at 60 ° C. and a molding pressure of 39.4 MPa to 58.8 MPa to obtain a molded product. This molded product at 160 ° C
Heat treatment is performed at a temperature of ˜220 ° C. for a predetermined time, and if necessary, scorch treatment is further performed at a temperature of 400 ° C. or higher.
In the present invention, these production methods are not particularly limited to the above-mentioned methods, but it is desirable to perform the heat treatment at a low temperature of 180 ° C. or to perform the heat treatment stepwise from a low temperature to a high temperature. That is, when heat-treated at a high temperature, unreacted substances and the like scatter, and a sufficient crosslinked structure cannot be obtained, but by sufficiently reacting at a low temperature, the crosslinking reaction of the phenol resin is completed,
The structure is stable against heat.

[0008]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. High ortho novolak type phenol resin, N with acrylonitrile bond content of 39%
Using a BR and a Nauta mixer, the formulations having the compositions shown in Table 1 were uniformly mixed, and the mixture was heated at 160 ° C. for 39.2.
Molding for 10 minutes using a molding die under the condition of MPa,
Then, after-baking was performed at 180 ° C. for 4 hours to prepare a friction material, and the squeaking characteristics of these materials were investigated.

[0009]

COMPARATIVE EXAMPLE A friction material was prepared in the same manner as in the examples using the compound having the composition shown in Table 1 using a high ortho novolak type phenol resin, NBR having a bound acrylonitrile content of 39% and a Nauta mixer. The squealing characteristics of these friction materials are shown in Table 1.

It can be seen that the friction materials of the examples of the present invention have excellent squealing characteristics because they are thermally stable, and no squealing occurs.

[0011]

[Table 1]

[0012]

According to the present invention, it is possible to provide a resin composition for a friction material which does not cause squeal.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // C08J 5/10 CFB 7188-4F (C08L 9/02 61:00) (72) Inventor Baba Hio, 1500 Ogawa, Shimodate, Ibaraki Prefecture, Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor Takaaki Kurita 1500, Ogawa, Shimodate City, Shimodate, Ibaraki Hitachi Shiseido Research Laboratory, Hitachi Chemical Co., Ltd.

Claims (3)

[Claims] 1. An NB having (a) a phenol resin and (b) a bound acrylonitrile amount of 35% or more as essential components.
A resin composition for a friction material comprising R, (c) metal fibers, (a) / (b) in a weight ratio of 2 to 5, and (c) in an amount of 20% by weight or more, further comprising a periodic table IIa group. A resin composition for a friction material comprising (d) chloride of the element, wherein (d) is 2 wt% to 15 wt% with respect to (a). 2. A resin composition for a friction material, wherein the phenol resin according to claim 1 is a high ortho novolac type phenol resin having an ortho ratio of 60% or more and an unreacted phenol amount of 3% by weight or less. .. 3. A resin composition for a friction material, wherein the metal fiber of claim 1 is a brass fiber or a copper fiber alone or as a mixture.