JPH05346129A - Disc brake pad - Google Patents

Abstract

PURPOSE:To prevent generation of rusts on the surface of a backing by adhering a friction material on the surface of this film after a metallic salt phosphate film having the specified film thickness is formed on the surface of the backing, and to maintain the excellent adhesive strength between the bakcing and the friction material for a long time. CONSTITUTION:A disc brake pad basically consists of a backing and a friction material. The backing is formed of metal. On the other hand, the friction material is formed out of a binding material composed of thermosetting resin of reinforced fiber, phenol resin or the like and a filler of graphite, barium sulfate or the like. In this case, metallic salt phosphate film whose film thickness is 5-20mum is formed on the surface of the backing. The friction material is adhered on the surface of metallic salt phosphate film through the adhesive or the like, or in a direct manner. This arrangement prevents generation of rusts on the surface of the backing and maintains the excellent adhesive strength between the backing and the friction material for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a bonding portion between a metal backing and a friction material in an automobile disc brake pad.

[0002]

2. Description of the Related Art Automobile brakes are roughly classified into drum brakes and disc brakes. Disc brakes often used in small cars press the disc brake pads so that they are sandwiched from both sides of a cast iron rotor that rotates with the wheels. The structure is such that the rotation of the rotor is decelerated or stopped.
By the way, recently, even in small cars, high horsepower cars have been developed, and the braking device has tended to be lighter in weight.Therefore, due to the structure of the disc brake pad, a large shearing force is applied in the wheel rotation direction. There is an increasing demand for mechanical strength.

On the other hand, as a main factor for lowering the strength of the disc brake pad, there is a problem that the adhesive strength with the friction material is lowered due to the generation of rust on the surface of the metal back metal. Under such circumstances, for the purpose of preventing rust from occurring on the disc brake pad and improving the adhesive strength, the back metal is immersed in an acid such as hydrochloric acid to activate the surface to remove rust, shot blasting or In some cases, a basic treatment such as removing rust on the surface of the backing metal with a barrel or the like and making the surface uneven at the same time is further subjected to primer treatment, nitriding treatment and the like.

[0004]

However, the primer treatment has drawbacks that it is difficult to mass-produce temperature control of baking when producing a uniform plastic film layer having a thickness of several μ, and the nitriding treatment is expensive. Further, only by immersing the back metal in an acid such as hydrochloric acid or making the surface uneven, rust is generated and the strength is lowered during long-term use of the disc brake pad. Therefore, the problem to be solved by the present invention is that the adhesive strength is high in view of the above problems, rust does not easily occur even after long-term use, and the processing control is easy in the actual manufacturing process. It is to provide a disc brake pad.

[0005]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and its constitution is such that a metal backing and a reinforcing fiber, a thermosetting resin such as a phenol resin are combined. In a disc brake pad composed of a friction material composed of a filler, graphite, barium sulfate, and other filler components, a metal backing metal surface is coated with a metal phosphate coating film having a thickness of 5 to 20 μm. It is what

That is, the inventors of the present invention have conducted extensive studies in order to obtain a disc brake pad which has a high rust preventive effect between the backing metal and the friction material and which can be easily manufactured. The present invention has been accomplished by knowing that the above problems can be solved by coating a salt film.
In the processing of the back metal of the pad, it is desirable to form irregularities of 5 to 50 μm in advance and then coat the metal phosphate coating film. If the irregularities are not formed, the effect is small.

The metal phosphate coating is obtained by immersing the back metal of the pad in a metal phosphate solution, washing with water and drying. or,
The metal phosphate coating preferably has a thickness of 5 to 20 μm.
If it is less than μm, the effect is small, and if it is more than 20 μm, the metal phosphate coating becomes easy to peel off. After that, a primer treatment or the like may be further applied, and an adhesive may be used for adhesion with the friction material, or it may be directly produced by integral molding.

[0008]

The disc brake pad according to the present invention comprises a metal backing, a reinforcing fiber, a binder made of a thermosetting resin such as phenol resin, and a friction material comprising a filler component such as graphite and barium sulfate. Since a metal phosphate coating is formed on the surface of the metal backing, rust is less likely to occur and the adhesive strength with the friction material is unlikely to decrease even after long-term use.

[0009]

EXAMPLES Next, examples of the present invention will be described. After degreasing the backing made of cast iron or aluminum and removing more rust and dirt from shot blasting, iron phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and calcium phosphate coatings are formed on the surface, respectively, and then the conventional Glass and aramid-based friction materials were molded and adhered by the method, and then heat treated to obtain disc brake pads of Examples A to E shown in Table 1. Further, a disc brake pad of a comparative example in which a metal phosphate coating was not formed was obtained in the same manner as in the example.

The composition of the friction material is glass fiber 10 wt.
%, Aramid fiber 10 wt%, metal powder 10 wt%, barium sulfate 25 wt%, phenol resin 15 wt%, cashew 10 wt%, and other fillers 20 wt%. Table 1 shows the results of the adhesion strength test after 2000 hours of salt spray and the rust area measurement of the back metal of the disc brake pads of Examples A to E and the comparative example manufactured by the above method.

[Table 1]

[0011]

As described above, the present invention comprises a metal backing, a reinforcing fiber, a binder made of a thermosetting resin such as phenol resin, and a friction material made of a filler component such as graphite or barium sulfate. As a result of forming a metal phosphate coating film having a film thickness of 5 to 20 μm on the surface of the metal back metal, the disc brake pad is suitable as a disc brake pad for an automobile because rust generation is reduced as described above.

Claims (1)

[Claims] 1. A disc brake pad comprising a metal backing metal, a reinforcing fiber, a binder made of a thermosetting resin such as phenol resin, and a friction material comprising a filler component such as graphite and barium sulfate. In the above, a metal phosphate coating having a film thickness of 5 to 20 μm is formed on the surface of the metal backing, and a friction material is directly bonded to the metal phosphate coating surface with an adhesive or the like. Disc brake pad featuring.