JPH08200411A - Brake piston - Google Patents

Abstract

(57) [Summary] [Structure] Phenolic resin and silica stone as filler
It is a brake piston formed by molding a phenol resin composition containing glass fiber and calcined clay, and it is preferable to use an acid catalyst such as salicylic acid as a curing catalyst for the phenol resin. [Effect] It is excellent in mechanical strength, abrasion resistance and brake fluid resistance and is lightweight, and when an acid catalyst is used as a curing catalyst, the brake fluid resistance is further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake piston for a disc brake made of a phenol resin, which has excellent wear resistance, brake fluid resistance and heat resistance.

[0002]

2. Description of the Related Art Conventionally, brake pistons for disc brakes are required to have heat resistance, wear resistance, brake fluid resistance, mechanical strength, etc., depending on the environment in which they are used. In order to satisfy these characteristics, a brake piston made of ceramic or metal has been used. In addition, a phenolic resin molding material is used as a plastic material because of its outstanding characteristics. Brake pistons made of ceramic or metal have a heavy solid weight,
There are problems such as long processing time and high cost. On the other hand, the phenol resin molding material has excellent heat resistance and mechanical strength, and a molded product can be easily obtained, so that its merit is very high. However, in order to impart such characteristics, glass fibers, silica and the like have been conventionally compounded as compounding base materials. In this case, although the mechanical strength and heat resistance are improved, the cost is increased and the wear resistance is significantly reduced.

[0003]

DISCLOSURE OF THE INVENTION The present invention replaces ceramics and metals used as conventional brake pistons for disc brakes with wear resistance and brake fluid resistance without impairing mechanical strength and heat resistance. The present invention provides a brake piston made of an excellent phenolic resin.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a brake piston formed by molding a phenol resin composition containing phenol resin and silica stone, glass fiber and calcined clay as a filler.

As the phenol resin, either a novolac type phenol resin or a resol type phenol resin may be used. Depending on the case, these two types may be used in combination. As the resol-type phenol resin, either dimethylene ether type or methylol type may be used. When a novolac type phenol resin is used, hexamethylenetetramine or the above-mentioned resol type phenol resin is used as a curing agent.

The silica stone preferably has a particle size of 10 μm to 300 μm. If it is less than 10 μm, workability is deteriorated when the composition is used as a molding material, and if it exceeds 300 μm, orientation occurs during molding, resulting in anisotropic difference in mechanical strength and poor dimensional accuracy, which is not preferable. Silica stone is phenolic resin 100
It is preferable to mix 200 to 350 parts by weight with respect to parts by weight. If it is less than 200 parts by weight, abrasion resistance and dimensional accuracy are lowered, and brake fluid resistance is also lowered. If it exceeds 350 parts by weight, the workability during materialization is poor and the fluidity at the time of molding is poor, making molding difficult.

Further, glass fibers are blended in order to maintain and improve the mechanical strength. The glass fiber content is preferably 80 to 120 parts by weight with respect to 100 parts by weight of the phenol resin. If it is less than 80 parts by weight, the mechanical strength will be insufficient, and if it exceeds 120 parts by weight, the mechanical strength will be anisotropic due to the orientation of the glass fibers, and the abrasion resistance will be reduced.
This is not preferable because it causes a problem that the dimensional accuracy becomes poor. Furthermore, the fiber length is preferably 500 μm to 5 mm. When it is less than 500 μm, the effect of increasing the strength, which is a characteristic of glass fiber, becomes small, which is not preferable. If it exceeds 5 mm, the productivity of the molding material is deteriorated, the orientation in the molded product is increased, the mechanical strength is anisotropic, and the dimensional accuracy is deteriorated, which is not preferable.

Further, in order to improve the resistance to brake fluid and the heat resistance, calcined clay is added. It is preferable to add 20 to 100 parts by weight of the baked clay to 100 parts by weight of the phenol resin. If less than 20 parts by weight, brake fluid resistance,
The effect on heat resistance is insufficient. Further, if it exceeds 100 parts by weight, abrasion resistance is deteriorated, which is not preferable.

In order to further improve the brake fluid resistance,
As the curing catalyst, it is preferable to use an acid catalyst instead of the usual alkali catalyst. Conventional phenol resin brake pistons usually use an alkali catalyst as a curing catalyst. In this case, there was a case where it was easily affected by the brake fluid and there was a problem with the durability as a brake piston.
This problem could be solved by using an acid catalyst. As the acid catalyst, imidodisulfonic acid, benzenesulfonic acid, toluenesulfonic acid, salicylic acid, oxalic acid, acetic acid, and acid salts thereof are used. These acid catalysts are used in an amount of 3 to 1 with respect to 100 parts by weight of the phenol resin.
It is preferable to use 0 part by weight. If it is less than 3 parts by weight, there is no effect in improving the resistance to brake fluid, and if it exceeds 20 parts by weight, curing will be too fast and molding will be difficult.

A molding material is obtained by adding a curing catalyst, a lubricant, a colorant and the like to the composition composed of the phenol resin and the filler and kneading with heating. Further, the molding material obtained by such a method is molded by injection molding, transfer molding, compression molding or the like to obtain a brake piston for a disc brake.

[0011]

In the present invention, since the apatite used is acicular crystals, not only it is possible to obtain excellent characteristics in mechanical strength due to the same effect as glass fiber, but it is more advantageous than glass fiber and silica. It has excellent wear resistance. Therefore, even if a large amount of silica stone is mixed, the mechanical strength is not lowered and the wear resistance is not impaired. Further, by using calcined clay, or calcined clay and an acid catalyst, it is possible to suppress dimensional changes, weight changes, and strength deterioration in the brake liquid due to the pH buffering effect of the brake liquid. Furthermore, in order to maintain and improve the mechanical strength, glass fibers are blended within a range that does not affect wear resistance. With such a compounding, it is possible to obtain a brake piston for a disc brake, which is made of a phenol resin composition and which is excellent in mechanical strength, wear resistance, brake fluid resistance and heat resistance.

[0012]

EXAMPLES Next, the present invention will be explained based on Examples and Comparative Examples. Here, "part" means "part by weight". The materials and formulations shown in Table 1 were kneaded with a heating roll to obtain a phenol resin molding material.

[0013]

[Table 1] (Note) Novolak resin Number average quantity 900 Resol resin Number average quantity 600 Silica stone Average particle size 50 μm Firing clay Average particle size 5 μm Glass fiber length 2 mm, Diameter 5 μm Silica average particle size 3 μm

In Examples 1, 2 and 3, novolac type, resol type, novolac type and resol type phenolic resins were used, respectively, and silica (comparative examples 1 and 2) as a conventional filler was replaced with silica stone. Is. Example 4,
In Nos. 5 and 6, the curing catalysts of Examples 1, 2, and 3 are replaced with slaked lime (alkali) by an acid catalyst (salicylic acid). Comparative Examples 3 and 4 are cases where the baked clay of Examples 1 and 4 was removed. For the molding materials obtained in each Example and Comparative Example, strength test, brake fluid resistance, heat resistance,
An evaluation such as a wear test was performed. The results are shown in Table 2.

[0015]

[Table 2]

[Measuring Method] (1) Bending Strength: According to JIS K7203. (2) Brake fluid resistance: 50 at 200 ° C in brake fluid
Bending strength retention rate, dimensional change rate, and weight change rate after 0 hour treatment were measured. (3) Heat resistance: The bending strength retention rate, the dimensional change rate, and the weight change rate were measured after treatment at 250 ° C. for 500 hours. (3) Wear resistance: According to a sliding wear test (counterpart material; S55
C)

[0017]

The brake piston obtained by molding the phenol resin composition using silica stone, glass fiber and calcined clay according to the present invention is excellent in mechanical strength, wear resistance and brake fluid resistance. It is also lightweight. In particular, when an acid catalyst is used as the curing catalyst, a brake piston with further improved brake fluid resistance can be obtained.

Claims (5)

[Claims] 1. A brake piston formed by molding a phenol resin composition containing a phenol resin and silica stone, glass fiber and calcined clay as a filler. 2. The brake piston according to claim 1, wherein an acid catalyst is used as a curing catalyst in an amount of 3 to 20 parts by weight based on 100 parts by weight of the phenol resin. 3. The silica stone is contained in an amount of 200 to 350 parts by weight with respect to 100 parts by weight of a phenol resin.
Or the brake piston according to 2. 4. The phenolic resin 100 is used as the glass fiber.
The brake piston according to claim 1 or 2, comprising 80 to 120 parts by weight with respect to parts by weight. 5. The phenolic resin 100 is used as the baked clay.
The brake piston according to claim 1 or 2, which is contained in an amount of 20 to 100 parts by weight with respect to parts by weight.