JPH05125357A - Friction material - Google Patents

Abstract

PURPOSE:To obtain a friction material capable of improving the bonding strength of a lining layer even by using a flat plate by joining a non-asbestos- based short fiber-containing lining layer to the plate made of a metal through a specific adhesive layer. CONSTITUTION:A friction material is obtained by joining a lining layer 14 which is a friction element containing non-asbestos-based short fiber 20 such as aramid short fiber blended therein to a plate 12 made of a metal through an adhesive layer 18 containing heat-resistant short fiber 22 such as aramid short fiber blended therein. The aramid short fiber as the heat-resistant short fiber 22 preferably has 5-20mum diameter and 0.5-1mm length and is blended in an amount of preferably 0.5-2vol%. Furthermore, e.g. an acrylonitrile- butadiene rubber adhesive or an epoxy-based adhesive is used as the adhesive.

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 brakes and clutches of vehicles and the like.

[0002]

2. Description of the Related Art A friction material used for a brake of a vehicle is a friction element in which metal powder such as iron and copper, inorganic short fiber, inorganic filler such as graphite, antimony oxide and barium sulfate is mixed. 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 been mainly used in the past, but in recent years, non-asbestos short fibers having excellent heat resistance such as aramid short fibers in place of asbestos short fibers from the viewpoint of pollution prevention. Is being used.

However, in a non-asbestos friction material in which a lining layer containing non-asbestos short fibers is bonded to a metal plate through an adhesive layer, the adhesive strength between the lining layer and the metal plate is asbestos. It was found to be inferior to the adhesive strength of the lining layer in the system friction material. If the strength of the non-asbestos fibers is lower than that of the asbestos fibers, and if the amount of the non-asbestos short fibers is set to the same level as that of the asbestos short fibers, the friction coefficient of the resulting friction material will be reduced. This is because the amount of asbestos-based short fibers to be blended must be smaller than that of asbestos-based short fibers. Therefore, the present inventors have
In order to improve the adhesive strength between the lining layer and the metal plate, it has been attempted to form rib-shaped projections on the adhesive surface of the metal plate with the lining layer, as proposed in Japanese Utility Model Publication No. 56-120440. It was

[0004]

By forming rib-shaped projections on the bonding surface of the metal plate with the lining layer in this manner, the bonding area between the metal plate and the lining layer can be increased, so that a flat metal plate can be formed. The adhesive strength can be improved as compared with the case where the lining layer is adhered to the plate. However, forming the rib-shaped projections on the joint surface of the metal plate with the lining layer complicates the process of processing the metal plate and increases the cost of the obtained friction material. In addition, since the joint surface of the metal plate becomes uneven, the adhesive layer formed on the joint surface of the metal plate tends to be nonuniform, 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 that can improve the adhesive strength of a lining layer even if it is a lining layer joined to a flat metal plate via an adhesive layer.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, applied an adhesive in which short aramid fibers were mixed in advance onto a flat metal plate, and then applied a lining layer. It was found that the adhesive strength of the lining layer can be improved by adhering the resin, and the present invention has been accomplished. That is, the present invention is 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 friction material is characterized in that heat-resistant short fibers such as aramid short fibers are mixed in the layer.

[0006]

When the cross section of the conventional non-asbestos friction material is observed under 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 peeled off from the metal plate, the gap between the lining layer and the adhesive layer is peeled off. In this respect, when observing the cross section of the friction material of the present invention with a microscope, a large number of heat-resistant short fibers blended in the adhesive layer are crosslinked between the lining layer and the adhesive layer, connecting both layers. Therefore, the adhesive strength of the friction material of the present invention can be improved as compared with the conventional non-asbestos friction material.

[0007]

The present embodiment will be described in more detail with reference to the drawings. FIG. 1a is a plan view showing an embodiment of this embodiment,
The friction material 10 includes a metal plate 12 having through holes 16 and 16 and a lining layer 14. The lining layer 14 is bonded to the metal plate 12 via an adhesive layer 18 as shown in FIG. 1b. The lining layer 14 is made of metal powder such as iron and copper, short aramid fiber, graphite,
Inorganic compounds such as antimony oxide and barium sulfate, and thermosetting resins such as phenolic resins are mixed.

FIG. 2 shows an enlarged view (micrograph) of the circle P in FIG. 1b. As shown in FIG. 2, the adhesive layer 18 for bonding the lining layer 14 and the metal plate 12 is
It has a thickness t of 0.05 to 0.15 mm and is mainly formed of a thermosetting adhesive which is a heat resistant adhesive. This is because the adhesive layer 18 needs heat resistance because it passes through the firing step in the friction material manufacturing step, as described later. Examples of such thermosetting adhesives include rubber-based adhesives 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 are blended with aramid short fibers 20 or aramid short fibers 22. In this aramid short fiber, the fiber length of the aramid short fiber 22 mixed in the adhesive layer 18 is shorter than the fiber length of the aramid short fiber 20 mixed in the lining layer 14. Of the aramid short fibers 22 in the adhesive layer 18, the aramid short fibers 22a existing near the interface with the lining layer 14 are crosslinked between the adhesive layer 18 and the lining layer 14 and connect both layers. The aramid short fiber 22 has a diameter of 5 to 20 μm and a length of 0.5 to 1 mm. Moreover, the compounding quantity is 0.5-
It is preferably 2.0 vol%. Aramid short fiber 22 content is less than 0.5 vol% or 2.0 vol%
If it 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, through holes are formed in a metal plate (hereinafter may be simply referred to as a plate), various surface treatments are performed on the plate, and then drying is performed. 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 adhesive strength between the la adhesive layer and the plate. Then, 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 when applied is set to 0.6 to 0.8 mm, and the thickness of the adhesive layer when dried is set to 0.2 to 0.4 mm.

The lining layer is formed separately from the plate processing step. In forming the lining layer, the raw materials are mixed, a predetermined amount is weighed, and preformed into a plate-like body. As the raw material of this example, iron, copper, aramid short fibers, graphite, antimony oxide, barium sulfate,
And phenolic resins are used. As the phenol resin, a thermosetting adhesive that forms the adhesive layer 18 (FIG. 2) can be used. The plate processed in this manner and the preformed plate-shaped body are integrated and subjected to heating and pressure molding. Such heating / pressurizing can be carried out by the method proposed in JP-A-2-292535. In this example, the friction material obtained by heating and press molding is fired for about 9 hours in a hot air oven maintained at about 180 to 230 ° C. Then, post-processing such as polishing for polishing the surface of the lining layer of the obtained friction material is performed to obtain a product.

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

In the embodiment described above, aramid short fibers are used as the short fibers to be mixed in the adhesive layer 14, but in addition, rock wool, carbon fibers, potassium titanate fibers and the like have good heat resistance. Fibers can be used. Needless to say, these fibers can also be used as the short fibers constituting the lining layer.

[0014]

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

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view showing an embodiment of the present invention.

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

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

[Explanation of symbols]

 10 Friction Material 12 Metal Plate 14 Lining Layer 18 Adhesive Layer 22 Heat Resistant Short Fiber

Claims (1)

[Claims] 1. A non-asbestos friction material in which a lining layer, which is a friction element containing non-asbestos short fibers such as aramid short fibers, and a metal plate are joined via an adhesive layer. A friction material having heat-resistant short fibers such as aramid short fibers mixed therein.