JP2779084B2 - Friction material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material, and more particularly, to a friction material used for a brake or a clutch of a vehicle or the like.

[0002]

2. Description of the Related Art Friction materials used for brakes of vehicles and the like are metal elements such as iron and copper, inorganic short fibers, graphite, antimony oxide, and inorganic fillers such as barium sulfate. A friction material in which a certain lining layer and a metal plate are joined via an adhesive layer is used. As such inorganic short fibers, asbestos short fibers have conventionally been mainly used, but in recent years, non-asbestos short fibers having excellent heat resistance such as aramid short fibers have been used in place of asbestos short fibers from the viewpoint of preventing pollution. Is being used.

However, a non-asbestos-based friction material in which a lining layer containing non-asbestos-based short fibers is bonded to a metal plate via an adhesive layer has an asbestos-based adhesive strength between the lining layer and the metal plate. It was found that the adhesive strength of the lining layer in the system friction material was inferior. If the strength of the non-asbestos fibers is lower than the strength of the asbestos fibers, and if the blending amount of the non-asbestos short fibers is approximately the same as that of the asbestos short fibers, the friction coefficient of the obtained friction material decreases. This is because the amount of the asbestos-based short fiber must be smaller than that of the asbestos-based short fiber. For this reason, the present inventors,
In order to improve the adhesive strength between the lining layer and the metal plate, an attempt was made to form rib-like projections on the bonding surface of the metal plate with the lining layer as proposed in Japanese Utility Model Application Laid-Open No. 56-120440. Was.

[0004]

By forming the rib-shaped projections on the surface of the metal plate to be bonded to the lining layer, the bonding area between the metal plate and the lining layer can be increased. Adhesive strength can be improved as compared with the case where the lining layer is adhered to the plate. However, forming the rib-like projections on the joint surface of the metal plate with the lining layer complicates the processing steps of the metal plate and increases the cost of the obtained friction material. In addition, since the joining surface of the metal plate is an uneven surface, the adhesive layer formed on the joining surface of the metal plate is also likely to be non-uniform, and the adhesive strength of the lining layer tends to be uneven. Therefore, an object of the present invention is to provide a non-asbestos-based friction material capable of improving the adhesive strength of a lining layer even if the lining layer is bonded to a flat metal plate via an adhesive layer.

[0005]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors applied an adhesive premixed with aramid short fibers on a flat metal plate, and then applied the lining layer. It has been found that the bonding strength of the lining layer can be improved by bonding, and the present invention has been achieved. That is, the present invention relates to a non-asbestos-based friction material in which a lining layer, which is a friction element mixed with non-asbestos-based short fibers such as aramid short fibers, and a metal plate are joined via an adhesive layer, A friction material characterized in that heat-resistant short fibers such as aramid short fibers are blended in a layer.

[0006]

When the cross section of the conventional non-asbestos friction material is observed with a microscope, the number of short fibers bridging between the lining layer and the adhesive layer is extremely small. Therefore, when the lining layer is separated from the metal plate, the lining layer and the adhesive layer are separated. In this regard, when the cross section of the friction material of the present invention is observed with a microscope, many of the heat-resistant short fibers blended in the adhesive layer are crosslinked between the lining layer and the adhesive layer to connect the two layers. For this reason, compared with the conventional non-asbestos-based friction material, the adhesive strength of the friction material of the present invention can be improved.

[0007]

This embodiment will be described in more detail with reference to the drawings. FIG. 1a is a plan view showing one embodiment of the present embodiment,
The friction material 10 includes a metal plate 12 having through holes 16, 16 perforated and a lining layer 14. The lining layer 14 is bonded to the metal plate 12 via the bonding layer 18 as shown in FIG. The lining layer 14 is made of metal powder such as iron and copper, aramid short fiber, graphite,
An inorganic compound such as antimony oxide and barium sulfate, and a thermosetting resin such as phenolic resin are blended.

FIG. 2 shows an enlarged view (micrograph) of the circled portion P in FIG. 1b. As shown in FIG. 2, the adhesive layer 18 that adheres to the lining layer 14 and the metal plate 12 includes
The thickness t is 0.05 to 0.15 mm, and is mainly formed by a thermosetting adhesive which is a heat resistant adhesive. This is because the adhesive layer 18 needs to have heat resistance because it passes through a firing step in the friction material manufacturing process, as described later. Examples of such a thermosetting adhesive include a rubber-based adhesive such as acrylonitrile-butadiene rubber (NBR);
Alternatively, a phenol-based or epoxy-based resin adhesive can be used.

In this embodiment, the lining layer 14 and the adhesive layer 18 contain aramid short fibers 20 or aramid short fibers 22. In such aramid short fibers, the fiber length of the aramid short fibers 22 blended in the adhesive layer 18 is shorter than the fiber length of the aramid short fibers 20 blended in the lining layer 14. Among the aramid short fibers 22 in the adhesive layer 18, the aramid short fibers 22 a existing near the interface with the lining layer 14 are crosslinked between the adhesive layer 18 and the lining layer 14 to connect both layers. Such aramid short fibers 22 have a diameter of 5 to 20 μm and a length of 0.5 to 1 mm. The compounding amount is 0.5 to
Preferably it is 2.0 vol%. The amount of the aramid short fiber 22 is less than 0.5 vol% or 2.0 vol%
When the ratio exceeds, the degree of improvement in the adhesive strength of the lining layer 14 tends to decrease.

The friction material 10 shown in FIGS. 1 and 2 can be manufactured by the process shown in FIG. First, a through-hole is formed in a metal plate (hereinafter, may be simply referred to as a plate), and the plate is subjected to various surface treatments and then dried. This surface treatment includes a degreasing step of degreasing the plate, and a shot processing step of spraying particulate matter toward the plate surface to increase the bonding strength between the adhesive layer and the plate. Next, a thermosetting adhesive such as NBR mixed with a predetermined amount of aramid short fibers is applied to the surface of the plate, and dried in a drying step. At this time, the thickness of the adhesive layer at the time of application is set to 0.6 to 0.8 mm, and the thickness of the adhesive layer at the time of drying is set to 0.2 to 0.4 mm.

[0011] Apart from such a plate processing step, a lining layer is formed. In forming the lining layer, the raw materials are mixed, weighed in a predetermined amount, and preliminarily formed into a plate. The raw materials of this example include iron, copper, aramid short fiber, graphite, antimony oxide, barium sulfate,
And phenolic resins. Note that a thermosetting adhesive that forms the adhesive layer 18 (FIG. 2) can be used as the phenolic resin. The plate processed in this way and the preformed plate-like body are integrated and subjected to heating and pressure forming. Such heat and pressure molding can be performed by the method proposed in JP-A-2-292535. In this embodiment, the friction material obtained by heating and pressing is fired for about 9 hours in a hot blast stove maintained at about 180 to 230 ° C. After that, the obtained friction material is subjected to post-processing such as polishing for polishing the surface of the lining layer to obtain a product.

The adhesive strength of the lining layer 14 of the thus obtained friction material of this embodiment was measured. The results are shown below. Further, as a comparison, in the process shown in FIG. 3, a friction material (comparative friction material) obtained in the same manner as in this example except that the adhesive was applied to the plate without blending the aramid short fiber in the adhesive. Of the lining layer was measured. The results are shown below. In addition, the measurement of the adhesive strength of the lining layer constituting the friction material was measured by JASO C
It was measured according to 437-84. Adhesive strength of lining layer Friction material of this example 63 kg / cm ² Comparative friction material 45 kg / cm ² Thus, in the friction material of this example, even if a flat plate is used, the adhesion strength of the lining layer Can be improved.

In the above-described embodiment, aramid short fibers are used as short fibers to be blended in the adhesive layer 14, but other materials such as rock wool, carbon fiber, potassium titanate fiber and the like have good heat resistance. Fiber can be used. In addition, it is needless to say that these fibers can also be used as short fibers constituting the lining layer.

[0014]

According to the present invention, even if a flat plate is used, the bonding strength of the lining layer of the non-asbestos-based friction material can be improved, so that the vehicle safety can be improved and the friction material can be manufactured. The productivity of the process can also be improved.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view showing one embodiment of the present invention.

FIG. 2 is an enlarged view of a circled portion P in FIG. 1b.

FIG. 3 is a process chart for manufacturing the friction material of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Friction material 12 Metal plate 14 Lining layer 18 Adhesive layer 22 Heat-resistant short fiber

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 3/14 F16D 69/00-69/04

Claims (1)

(57) [Claims] 1. A non-asbestos-based friction material in which a lining layer, which is a friction element containing non-asbestos-based short fibers such as aramid short fibers, and a metal plate are joined via an adhesive layer, the adhesive layer A friction material comprising heat-resistant short fibers such as aramid short fibers.