JP2002266915A - Automobile non-asbestos disc brake pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disc brake pad that can reduce the sound pressure of a creep groan by excluding moisture from a transfer film and suppressing generation of rust caused by adsorbed moisture, and a disc brake pad that can improve the effectiveness of a brake without generating a brake judder. SOLUTION: The automobile non-asbestos disc brake pad includes a fiber backing, a binder and a friction modifier, wherein the binder at least includes a silicone-modified resin, and the friction modifier includes an abrasive of a mean particle diameter of 0.5 to 5 μm and Mohs' hardness of 7 or more, and an organic filler including cashew dust of a mean particle diameter of 250 μm or less. The automobile non-asbestos disc brake pad alternatively includes a fiber backing, a binder and a friction modifier, wherein the binder at least includes a silicone-modified resin, and the friction modifier includes an abrasive of a mean particle diameter of 0.5 to 5 μm and Mohs' hardness of 7 or more, and an organic filler including isoprene rubber and cashew dust of a mean particle diameter of 250 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-asbestos disc brake pad for a vehicle (hereinafter referred to as a disc brake pad).

[0002]

2. Description of the Related Art Disc brakes are used in braking devices of automobiles, and there are disc brake pads as sliding members. A conventional disk brake pad is disclosed in JP-A-49-21544, lubrication: Vol.
1974), a binder containing a thermosetting resin such as a phenolic resin or a fiber base such as a metal fiber, an inorganic fiber or an organic fiber, and a lubricant such as graphite or antimony trisulfide as a friction modifier. Powder such as iron, copper, brass, filler such as barium sulfate, calcium carbonate, cashew dust, N
Disc brake pads formed by heating and pressing a mixture containing an organic friction modifier such as BR and SBR are generally used. Also, to improve the coefficient of friction, alumina,
It is known to use an abrasive having a Mohs hardness of 7 or more, such as silica or zircon sand.

However, an automobile using the above-mentioned conventional disc brake pad generates noise called creep grown (goo noise). This noise is considered to cause stick-slip vibration when the creep torque of the automatic transmission is applied to the disk, and the stick-slip vibration resonates to become noise. Also, the frequency of this noise is usually about 200 to 300 Hz. After parking the vehicle for a long time, especially after parking (leaving) overnight at night when the temperature and humidity change greatly, when restarting the operation, The creep grone suddenly grew larger, giving the driver discomfort.

The main cause of this is that when a car is parked overnight at night, moisture is adsorbed on the transfer film formed on the surface of the disk rotor, and this moisture causes rust between the disk rotor and the transfer film, causing a re-operation. It is believed that the transfer film peels off at the beginning of operation and increases the noise level of the creep grown.

[0005] A further problem of the present invention is to increase the coefficient of friction of a disc brake pad. The disc brake pad is required to have a high friction coefficient from the viewpoint of reducing the weight of the vehicle. However, if the friction coefficient is increased, the disk rotor of the mating material is ground. This grinding causes the thickness of the disk rotor to be non-uniform, causing a brake judder that generates vibration during braking.

[0006]

The first, second and third aspects of the present invention do not attract moisture to the transfer film, further suppress the generation of rust caused by the absorbed moisture, and reduce the sound pressure of the creep grown. An object of the present invention is to provide a disc brake pad which can increase the braking effect without generating a disc brake pad which can be lowered and a brake judder.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a non-asbestos disc brake pad for automobiles containing a fiber base material, a binder and a friction modifier, wherein the binder comprises at least a silicone-modified resin, and the friction modifier comprises Has an average particle size of 0.5 to
5 μm abrasive with Mohs hardness of 7 or more and average particle size of 250
The present invention relates to a non-asbestos disc brake pad for automobiles, comprising an organic filler containing cashew dust of not more than μm.
Further, the present invention relates to a non-asbestos disc brake pad for automobiles containing a fiber base material, a binder and a friction modifier, wherein the binder contains at least a silicone-modified resin, and the friction modifier has an average particle size of 0.1. Grinding material with Mohs hardness of 7 or more at 5-5 μm, isoprene rubber and average particle size of 250 μm
The present invention relates to a non-asbestos disc brake pad for automobiles containing an organic filler containing cashew dust of not more than m. Further, the present invention relates to the above non-asbestos disc brake pad for automobiles, wherein the fiber base material comprises an aramid fiber, an alumina silica fiber, a potassium titanate fiber and a copper fiber.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As the binder in the present invention, a conventionally known binder is used without any particular limitation. By using a silicone-modified resin for part or all of the binder, the surface of the disc brake pad has improved water repellency. The occurrence of brake judder can be suppressed. As the silicone-modified resin, it is preferable to use a novolak-type phenol resin which has been reacted with silicone oil or silicone rubber, or a novolak-type phenol resin in which silicone rubber has been finely dispersed. The content of the silicone-modified resin is preferably 3 to 30% by volume in the total composition, and
More preferably, the content is 0 to 25% by volume.

As abrasives having a Mohs hardness of 7 or more contained in the friction modifier, alumina, zircon sand, silica,
Mullite, talc, clay and the like are preferable, and the average particle size of each is 0.5 to 5 μm, preferably 0.8 to 4 μm,
More preferably, it is in the range of 1 to 3 μm, and 0.5 μm
If it is less than 3, the coefficient of friction cannot be increased. On the other hand, if it exceeds 0.5 μm, the disk rotor of the partner material will be ground. Although the average particle size is in the above range, the maximum particle size is preferably 50 μm or less. These abrasives are used in the total composition in the range of 0.1 to 10% by volume, respectively, and it is preferable to use one of them or a combination of two of them.

In the present invention, an organic filler containing cashew dust is used as a friction modifier, and its average particle size is 250 μm or less, preferably 150 to 250 μm.
μm, more preferably in the range of 200 to 230 μm, and if it exceeds 250 μm, the friction coefficient cannot be increased. The average particle size is in the above range, but the maximum particle size is preferably 400 μm or less. The content of cashew dust is preferably 5 to 20% by volume, more preferably 10 to 18% by volume in the whole composition. In the present invention, isoprene rubber and cashew dust having an average particle size of 250 μm or less may be used in combination as the organic filler.

The fiber base material used in the present invention is an organic fiber such as aramid fiber, acrylic fiber, phenol fiber or the like, an inorganic fiber such as glass fiber, ceramic fiber, rock wool, wollastonite, carbon fiber or potassium titanate fiber. , Steel fiber, copper fiber, inorganic fiber such as brass fiber,
One or more kinds of metal fibers such as iron fibers, copper fibers, and brass fibers can be used. The content of the fibrous base material is preferably 20 to 45% by volume, more preferably 25 to 45% by volume in the whole composition.

As the binder used in the present invention, phenol resins and their modified resins, polyimide resins, furan resins and the like can be used in combination. When used in combination, the content is 10 to 30% by volume in the total composition.
And more preferably 15 to 25% by volume.

In addition to the above-mentioned abrasives having a Mohs' hardness of 7 or more, cashew dust, isoprene rubber, inorganic friction such as graphite, antimony trisulfide, molybdenum disulfide, barium sulfate, magnesium carbonate, mica, zirconia, etc. One or more kinds of modifiers, metal powders such as iron, brass, tin, and zinc, and organic friction modifiers such as acrylic rubber, NBR, and SBR can be used in combination. When used in combination, the content is 20 to 70% by volume in the total composition.
And more preferably 35 to 55% by volume. These components are blended so that the total composition becomes 100% by volume. In the present invention,
The volume% of each component is a value calculated by dividing the used weight of the component by the density of the component.

In the disc brake pad of the present invention, a composition containing a fiber base material, a binder and a friction modifier is uniformly mixed, preformed, and then a backing metal and a preformed body are inserted into a mold. Thereafter, it is obtained by molding by a heat and pressure molding method, and then subjected to heat treatment. The molding temperature is 130 to 170
C is preferable, and 140 to 160 C is more preferable. The pressure is preferably from 20 to 60 Mpa, more preferably from 30 to 50 Mpa. The heat treatment temperature is preferably from 100 to 300 ° C, more preferably from 150 to 250 ° C. The conditions of heating and pressurizing during molding and the conditions of post heat treatment are determined by
The pad is adjusted so that the amount of moisture absorption (the amount of water absorbed by the weight of the molded body) is 0.5% or more.
Since it varies depending on the type of the resin used as the binder, it is appropriately determined according to the resin.

An embodiment of the present invention will be described below. Example 1 Comparative Examples 1, 2, 3 and 4 A predetermined amount of each component shown in Table 1 was blended to prepare each blend of Example 1 Comparative Examples 1, 2, 3 and 4. After uniformly mixing the mixture in a mixer, pre-molding, then inserting a backing metal and a pre-molded body in a mold, and then heat-press molding at a temperature of 140 ° C. and a pressure of 40 MPa for 10 minutes, Thereafter, heat treatment was performed at 200 ° C. for 6 hours to obtain a disc brake pad. As the silicone-modified resin shown in Table 1, a novolak-type phenol resin (trade name: RS2210MB, manufactured by Mitsui Chemicals, Inc.) reacted with silicone rubber was used.

[0016]

[Table 1]

Next, the disc brake pad of the present invention and the disc brake pad of the comparative example are incorporated in an automobile,
The vehicle was parked (left alone) overnight to perform a comparison test of the sound pressure level of the creep grone. The evaluation of the creep grone is performed by loosening the brake pedal while slowly starting the above-mentioned automobiles, stopping, and then slowly releasing the brake pedal again.
The sound pressure of the creep groon generated when the brake pedal was released repeatedly was measured with a sound level meter.

As a result, the sound pressure of the disc brake pad according to the present invention was as follows in Example 1 and Comparative Examples 1, 2 and 3, respectively.
The disc brake pads of Comparative Example 4 showed high values of up to 76, whereas the low values were 68, 68, 68, and 68 dB.

Further, the coefficient of friction of Example 1 and Comparative Example was measured according to JASO-C-406. As a result, in Example 1 and Comparative Example 2, 0.40 and 0.42
And a high coefficient of friction was obtained. Comparative Example 4 used a phenol resin as a binder and had a friction coefficient of 0.35. However, even when a silicone-modified resin was used as in Comparative Example 3, cashew dust having an average particle size of 200 μm and an average particle size of 200 μm were used. When 4 μm alumina was used, the coefficient of friction dropped to 0.33. In addition, when cashew dust having a large average particle size was used as in Comparative Example 1, the friction coefficient was 0.35, and a high effect was not obtained.

Further, the wear amount of the disk rotor was measured by pressing a 25 mm square test piece against the disk rotor at 0.07 MPa for 24 hours. In Example 1, Comparative Examples 1, 3 and 4, the rotor wear amount was 2.0
μm, 1.8 μm, 1.6 μm, and 1.6 μm, the disk rotor wear was small. However, when alumina having a large average particle size was used as in Comparative Example 2, the rotor wear was
The disc rotor wear was as large as 10.2 μm.

From the above test results, by using a silicone-modified resin as a binder, moisture is not attracted to the transfer film, a rust-preventing effect is exhibited, the sound pressure of the creep grown can be reduced, and the use of a silicone-modified resin is also possible. In this case, the friction coefficient is lower than when phenol resin is used, but the wear of the disk rotor is increased by using abrasives having an average particle size of 0.5 to 5 μm and cache dust having an average particle size of 250 μm or less. It is clear that the coefficient of friction can be increased without any.

[0022]

According to the disk brake pads of the first, second and third aspects, it is possible to suppress the generation of rust caused by the adsorbed moisture without adhering moisture to the transfer film, and to reduce the sound pressure of the creep grown. In addition, it is a disc brake pad that is industrially extremely suitable because it can enhance the braking effect.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08L 77/10 C08L 77/10 83/04 83/04 97/02 97/02 (72) Inventor Shigeru Kudo Hitachi, Ibaraki Hitachi Chemical Industry Co., Ltd., Yamazaki Office 3-72-1, Ayukawa-cho, Hitachi City (72) Inventor Hiromitsu Yamamoto 3-3-1 Ayukawacho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd., Yamazaki Office (72) Inventor Three Takahiro Ubu 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Hiroyuki Nakanishi 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. 2 Takaracho Nissan Motor Co., Ltd. F-term (reference) 3J058 BA21 BA26 BA28 BA76 CA42 FA01 GA03 GA04 GA07 GA13 GA15 GA16 GA20 GA23 GA24 GA26 GA27 GA28 GA33 GA34 GA37 GA38 GA43 GA45 GA48 GA50 GA55 GA59 GA62 GA64 GA65 GA92 4F071 AA41 AA31A AA56 AA60 AA67 AA73 AB03 AB07 AB08 AB12 AB18 AB20 AB26 AB28 AB30 AD01 AH07 DA05 4J002 AC07X AC08X AH00X BG00X BG00Y CC03Y CC03Z CL06Y CM04Z CP03W DA016 DA076 DA086 DC006 DE097 DE147 DE186 DJ006 DJ007 DJ016 DJ017 DJ037 DJ047 DL006 FA04Y FA046 FD01X FD207 GM03 GN00

Claims (3)

[Claims] 1. A non-asbestos disc brake pad for automobiles comprising a fiber base material, a binder and a friction modifier, wherein the binder comprises at least a silicone-modified resin, and the friction modifier has an average particle size of 0.5. A non-asbestos disc brake pad for automobiles, comprising a grinding material having a Mohs hardness of 7 or more and a mean particle size of 250 μm or less and an organic filler containing cashew dust of up to 5 μm. 2. A non-asbestos disc brake pad for automobiles comprising a fiber base material, a binder and a friction modifier, wherein the binder comprises at least a silicone-modified resin, and the friction modifier has an average particle size of 0.5. A non-asbestos disc brake pad for automobiles, comprising a grinding material having a Mohs hardness of not less than 7 and an organic filler containing cashew dust having an average particle diameter of not more than 250 μm. 3. The non-asbestos disc brake pad for an automobile according to claim 1, wherein the fiber base material comprises an aramid fiber, an alumina silica fiber, a potassium titanate fiber and a copper fiber.