JPH09280285A - Friction material for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the generating frequency of squeak by a brake device during starting by a method wherein at least a part of organic fibers, such as Aramid fibers, contained in a friction material is present in a pill-form non- opening state. SOLUTION: Mixed organic fibers, such as Aramid fibers, are dispersed in a lining layer of which a friction material consists, and the organic fibers being present is present in a monofilament 14 state and the fibers present in a pill-form non opening fiber lumps 16, 16,... are mixed together. The pill-form non-opening lump 16 part is dispersed and formed in density lower than that of a part present in the monofilament 14 state. Thereby, a dense part and a coarse part are mixed together in the lining layer and as a result of vibration transmitted through the lining layer being absorbed by the coarse part and damped, the occurrence frequency of squeak during brake is decreased. It is preferable that the spill-form non-opening lump 16 has a diameter of 0.5-5mm. Further, it is preferable that a mixture amount of the non-opening lump 16 is 1-10vol.% based on a whole amount of a lining layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle friction material, and more particularly to a vehicle friction material containing an organic fiber such as aramid fiber as a fiber component.

[0002]

2. Description of the Related Art As a vehicle friction material used for a vehicle brake device, a clutch, etc., as disclosed in Japanese Patent Laid-Open No. 212582/1990, a fade phenomenon is improved as compared with the conventionally used asbestos. Therefore, a friction material for vehicles in which aramid fibers are dispersed and mixed has been proposed.

[0003]

As described above, the fade phenomenon of the obtained friction material can be suppressed by dispersing and mixing the aramid fiber in the friction material. However, in a friction material in which aramid fibers are dispersed and mixed, a phenomenon in which abnormal noise is generated from a braking device during braking, a so-called "squealing" phenomenon (hereinafter simply referred to as "squeaking") frequently occurs, so that the frequency of this squealing is reduced. Is requested. Therefore, an object of the present invention is to provide a vehicle friction material containing an organic fiber such as aramid fiber, which can reduce the frequency of squeaking generated from a brake device during braking.

[0004]

Means for Solving the Problems As a result of studies to solve the above-mentioned problems, the present inventor has found that according to the friction material in which a part of the aramid fibers remains as a pill-shaped undisentangled mass, all the aramid fibers are The inventors have found that the frequency of squeaking during braking is lower than that of a friction material that is dispersed and mixed, and have reached the present invention.
That is, the present invention is a vehicle friction material containing an organic fiber such as aramid fiber as a fiber component, wherein at least a part of the organic fiber is present in a pill-like undisentangled mass. It is in. In the present invention, the pill-like undisentangled mass is 1 to 10% by volume of the total friction material volume.
And / or the diameter of the pilled, undisentangled mass is 0.5
By setting the thickness to 5 mm, the squeal occurrence frequency can be reduced while substantially maintaining the strength of the friction material.

[0005]

1 shows an example of a vehicle friction material of the present invention. The vehicle friction material of FIG. 1 (hereinafter, may be simply referred to as friction material) has a lining layer 12 bonded to one surface side of a metal plate 10. The lining layer 12 constituting such a friction material is a fiber component composed of organic fibers such as aramid fibers, carbon fibers, rock wool, ceramic fibers, inorganic fibers such as glass fibers, metal fibers such as copper fibers, phenolic resin, fluororesin. , A binder such as aromatic resin, and a filler such as metal powder such as copper powder, graphite, rubber powder, cashew dust, calcium carbonate, barium sulfate, and the like.

Lining layer 12 constituting such a friction material
When the ground surface of No. 1 is observed with a microscope, organic fibers such as aramid fibers are dispersed in single fibers 14, 14, ... Is mixed with. In this way, a part of the organic fiber such as aramid fiber is a pill-like undisentangled mass 16, 16
According to the friction material including the lining layer 12 existing in ..., The frequency of squeaking during braking can be reduced. The detailed reason for this is currently under consideration, but is considered as follows. That is, in the lining layer 12 constituting the friction material shown in FIG. 1, the blended organic fibers such as aramid fibers are dispersed and present as the single fibers 14, and the pill-like undisentangled mass 16 , 16 ... Also exist. Since the portion of the pill-like undisentangled lumps 16 has a lower density than the portion existing as dispersed single fibers 14, in the lining layer 12,
A dense part and a rough part coexist.

By the way, generally, as the density of the transmission medium is higher, the vibration is transmitted through the medium with less damping, but as the density of the medium is lower, the vibration is transmitted through the medium while being absorbed by the medium. Therefore, the degree of attenuation increases. Therefore, when a dense portion and a rough portion are mixed in the lining layer 12 like the lining layer 12 constituting the friction material of the present invention, the vibration transmitted through the lining layer 12 is in the rough portion. As a result of being absorbed and damped, the frequency of squeaking during braking can be reduced. Such fluffy undisentangled mass 16,
16 ... has a diameter of 0.5 to 5 mm, especially 1 to 3 m.
m is preferable. When the diameter of the fluffy undisentangled mass 16 is less than 0.5 mm, the coarse portion becomes insufficient, and the frequency of squeaking during braking tends not to be sufficiently reduced. On the other hand, if the diameter of the fluffy undisentangled mass 16 exceeds 5 mm, the strength of the lining layer 12 tends to decrease. Further, the blending amount of the fluffy undisentangled mass 16 is preferably 1 to 10% by volume, and particularly preferably 3 to 8% by volume with respect to the total amount (total volume) of the lining layer 12. If the blending amount of the fluffy undisentangled mass 16 is less than 1% by volume, the coarse portion becomes insufficient, and the squeaking frequency during braking tends not to be sufficiently reduced. On the other hand, when the blending amount of the fluffy undisentangled mass 16 exceeds 10% by volume, the strength of the lining layer 12 tends to decrease.

The friction material shown in FIG.
It can be manufactured under the manufacturing conditions described in JP-A-35-35, JP-A-3-28534 and the like. That is, on a metal plate 10 that has been subjected to surface treatment and the like and dried, a mixture obtained by mixing a predetermined amount of a fiber component, a binder and a filler is preliminarily molded into a predetermined shape, and a lining material is placed thereon. It is manufactured by performing post-processing such as surface grinding of the lining layer 12 obtained by heating / pressurizing and then firing. The friction material of the present invention can be obtained by introducing organic fibers such as aramid fibers into the mixer immediately before the mixing of the friction material is completed in the method for producing the friction material. In this way, since the defibration of the organic fibers such as the aramid fibers, which is added to the mixer immediately before the mixing of the friction material is completed, is insufficiently defibrated, and a part of the fibril-like undefibrated mass 16 remains as it is. is there. As the organic fiber such as aramid fiber, aramid short fiber can be preferably used. As such aramid short fibers, those having a diameter of about 10 to 14 μm and a length of about 0.5 to 3.0 mm are preferable. still,
A predetermined amount of organic fibers such as aramid fibers may be converged in advance with a sizing agent or the like.

Here, aramid short fibers were used as the organic fibers, and a predetermined amount of aramid short fibers was put into a mixer immediately before the mixing of the friction material was completed, and the friction material shown in FIG. ). As a result of observing the lining layer 12 constituting the obtained friction material, as shown in FIG. 2, the single fibers 14 and the pill-shaped undisentangled mass 16 are mixed, and the diameter of the pill-shaped undisentangled mass 16 is increased. Was 0.5 to 5 mm. Next, the amount of aramid short fibers introduced into the mixer was changed, and the frequency of squeaking during the braking of the obtained friction material was investigated. The result is shown in FIG. Further, as a comparative example, a friction material was manufactured in the same manner as in the example, except that a predetermined amount of aramid short fibers was added from the beginning of mixing of the friction material. Lining layer 1 constituting the obtained friction material
When No. 2 was observed, it was substantially only the single fiber 14. Also in this case, the squeal occurrence frequency during braking was examined for the friction materials obtained by changing the amount of aramid short fibers to be put into the mixer. The results are also shown in FIG. As is clear from FIG. 3, the squeal occurrence frequency during braking is lower in the friction material of the example than in the friction material of the comparative example. Further, in the relationship between the frequency and the undefibrated lump content of short aramid fibers, when the content is 1% by volume or more, the squeal occurrence frequency sharply decreases as compared with the content of less than 1% by volume. There is a tendency.

Further, the shear strength (in accordance with JIS-D4422) of the lining layer 12 of the friction material obtained in the example was measured, and the result is shown in FIG. As is clear from FIG. 4, when the content of undisentangled lumps of aramid short fibers exceeds 10% by volume, the degree of decrease in shear strength of the lining layer 12 tends to increase. Therefore, from FIGS. 3 and 4, by setting the content of undisentangled lumps of aramid short fibers to 1 to 10% by volume, the squeal occurrence frequency during braking can be suppressed while maintaining the shear strength of the lining layer 12. The material can be obtained. Although aramid short fibers are used in FIGS. 3 and 4, polyether ether ketone (PEEK) and polyphenylene sulfide (PPS) are used.
These organic fibers may be used alone or in combination.

[0011]

EFFECTS OF THE INVENTION According to the present invention, squealing at the time of braking is achieved by a simple means in which a part of organic fibers such as aramid fibers mixed in the friction material is present in the friction material as a pill-like undisentangled mass. As a result of suppressing the generation frequency, it is possible to maintain the characteristics of the friction material, suppress the increase in manufacturing cost, and prevent the generation of squeal during braking as much as possible.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a friction material according to the present invention.

FIG. 2 is a lining layer 12 constituting the friction material shown in FIG.
It is an explanatory view for explaining a result of magnified observation.

FIG. 3 is a graph showing a relationship between an undisentangled lump content rate of aramid short fibers and a squeal occurrence frequency.

FIG. 4 is a graph showing the relationship between the content of undisintegrated lumps of aramid short fibers and the shear strength of the lining layer 12 constituting the friction material shown in FIG.

[Explanation of symbols]

 10 metal plate 12 lining layer 14 monofilament 16 pill-like aramid short fiber undisentangled mass

Claims (3)

[Claims] 1. A vehicle friction material containing an organic fiber such as aramid fiber as a fiber component, wherein at least a part of the organic fiber is present in a pill-like undisentangled mass. 2. The fluffy, undisentangled mass is 1 to 1 of the total friction material volume.
The friction material for vehicles according to claim 1, which is 10% by volume. 3. The diameter of the fluffy, undisentangled mass is 0.5 to 5 mm.
The friction material for vehicles according to claim 1 or 2.