KR101777423B1 - Disc brake pad - Google Patents

Abstract

[assignment]
A disc brake pad comprising a fiber base material, a binder, a grinding material, and a friction material containing a friction / wear adjustment material, which is used for a disc brake having a disc rotor composed of an iron-based material, Provided is a brake pad provided with a friction material having excellent fade resistance, abrasion resistance, and moldability.
[Solution]
Wherein the friction material used for the disc brake pad is composed of a fiber base material, a binder, a grinding material, and a friction / wear adjustment material, and the filler is contained in an amount of 4.5 to 7.0% by weight based on the total amount of the friction material, At least 50% by weight of the abrasive particles, and an inorganic particle having an Mohs hardness of 6 to 8 and an average particle size of 10 to 200 占 퐉 in an amount of 1 to 3% by weight based on the total amount of the friction material.
Further, the friction material contains 20 to 30% by weight of the titanate of the alkali metal and / or alkaline earth metal with respect to the total amount of the friction material, and 3 to 5% by weight of the cashew dust with respect to the total amount of the friction material.

Description

DISC BRAKE PAD {DISC BRAKE PAD}

The present invention relates to a disc brake pad having a friction material containing a fiber base material, a binder, an abrasive material, and a friction / wear adjustment material, which is used in a disc brake of a vehicle.

BACKGROUND ART [0002] Conventionally, a disc brake is used as a braking device of an automobile, and a disc brake pad having a friction member attached to a metal base member is used as the friction member.

Japanese Patent Laid-Open Publication No. 2006-275198 (Patent Document 1) discloses a disc brake pad in which a friction material containing a fibrous base material, a binder and a filler is adhered to a back plate, wherein the friction material is composed of a straight phenolic resin and a phenol aralkyl resin Is contained in a mass ratio of 85:15 to 65:35. According to this disc brake pad, maintenance of durability, generation of crying, and cracking and peeling at the end and vicinity of the friction material and the back plate adhesion surface can be reduced under a high load condition for the friction material.

BACKGROUND ART [0002] In recent years, in order to improve fuel economy and operability of a vehicle, it is required to reduce the weight of the vehicle component parts. As a method for reducing the weight, there is a method of reducing the density of the material used as the component, the thickness of the component, and the miniaturization. However, in the components of the brake, it is required to reduce the size of the brake system, particularly the disc rotor.

Even in the case where the disk rotor is downsized, since the braking performance equivalent to that of the conventional disk rotor is required, a greater load is applied to the friction material of the disk brake pad used as the disk rotor and the set. Therefore, the friction material is required to have higher fade resistance.

In order to improve the fade resistance of the friction material, cryolite may be added to the friction material. However, when the friction material containing cryolite is heated to a high temperature by friction at the same time, the cryolite is melted in the surface layer portion of the friction material, and when the friction material and the disk rotor are kept in close contact with each other, There is a problem that sticking phenomenon occurs in which the friction material is solidified and the disk rotor is fixed.

Japanese Patent Application Laid-Open No. 2009-132816 (Patent Document 2) discloses a non-asbestos friction material comprising a fibrous base material, a binder, a lubricant, and other filler, and containing pyrophosphoric acid calcium as a filler, . Also disclosed is a non-asbestos friction material containing 4 to 6 vol% of calcium pyrophosphate and 3 to 5 vol% of cryolite as the filler.

The sticking phenomenon which has been considered to be derived from cryolite has been effectively suppressed by the method described in Patent Document 2, but in recent years, the sticking phenomenon of the friction material not containing cryolite has become remarkable.

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-275198 Patent Document 2: JP-A-2009-132816

The present invention relates to a disc brake pad comprising a fiber base material, a binder, a grinding material, and a friction material containing a friction / wear adjustment material, which is used for a disc brake including a disc rotor made of an iron-based material, And which has a friction material excellent in fade resistance, abrasion resistance, and moldability while effectively suppressing wear and tear of the disc brake pad.

It is presumed that the sticking phenomenon that occurs when a disc brake pad having a friction material not containing cryolite is used as a set with a disc rotor made of an iron material is caused by the following mechanism.

A friction material is added to the friction material of the disc brake pad to improve the friction coefficient. When the disc rotor composed of the iron-based material is ground by this grinding material at the braking operation, the grinding powder of the disc rotor is transferred to the surface of the friction material to form the iron coating on the surface of the friction material. On the other hand, when the frictional surface of the disk rotor and the friction material becomes high in temperature due to the simultaneous friction heat, the thermosetting resin included as a binder of the friction material is thermally decomposed to generate gas. When the temperature of the friction surface reaches the combustion temperature of the gas, the gas burns. By this combustion, the iron film formed on the surface of the friction material is heated, and the amount of oxygen in the vicinity of the friction surface is remarkably reduced. At the end of this combustion, oxygen rapidly flows into the friction surface and comes into contact with the iron coating on the surface of the heated friction material. As a result, oxygen and iron undergo a rapid oxidation reaction to produce molten slag of iron oxide. When the friction material and the disc rotor are maintained in a close state, the slag of the molten iron oxide is solidified due to the lowering of the temperature of the friction material, resulting in a sticking phenomenon.

From the above-described mechanism, the present inventors have found that, in order to suppress the sticking phenomenon that occurs when the disc rotor is made of an iron-based material, the present inventors have found that (1) a thermosetting resin, which generates little gas at high temperature and has high heat resistance, 2) It has been found effective to adjust the Mohs hardness, the average particle diameter and the addition amount of the abrasive so as not to excessively grind the disk rotor.

The present invention is a disc brake pad comprising a fiber base material, a binder, a grinding material, and a friction material containing a friction / wear adjustment material, which is used for a disc brake having a disc rotor made of an iron-based material, and is based on the following technique .

(1) A disc brake pad comprising a fiber base material, a binder, a grinding material, and a friction / wear adjustment material used for a disc brake having a disc rotor made of an iron-based material, wherein the friction material is a friction material, By weight based on the whole amount of the binder, 4.5 to 7.0% by weight of the inorganic particles having an Mohs hardness of 6 to 8 and an average particle size of 10 to 200 탆 in an amount of at least 50% 1 to 3% by weight based on the total weight of the disc brake pad.

(2) The disc brake pad according to (1), wherein the friction material contains a titanate of an alkali metal and / or an alkaline earth metal in an amount of 20 to 30% by weight based on the total amount of the friction material.

(3) The disc brake pad according to (1) or (2) above, wherein the friction material contains cashew dust in an amount of 3 to 5% by weight based on the total amount of the friction material.

According to the present invention, there is provided a disc brake pad comprising a fiber base material, a binder, a grinding material, and a friction material containing a friction / wear adjustment material, which is used for a disc brake including a disc rotor made of an iron- It is possible to provide a disc brake pad having excellent fade resistance and wear resistance.

1 is a perspective view of a disc brake pad;

The friction material of the disc brake pad of the present invention contains the binder in an amount of 4.5 to 7.0% by weight based on the total amount of the friction material, and the at least 50% by weight of the aralkyl-modified phenolic resin in the total amount of the binder. The total content of the binder is preferably 4.5 to 7.0% by weight based on the total amount of the friction material. If it is less than 4.5% by weight based on the total amount of the friction material, the abrasion resistance is lowered. If it is 7.0% by weight or more based on the total amount of the friction material, the fade resistance is lowered. The aralkyl-modified phenol resin is a resin having an aralkyl group that does not have a phenolic hydroxyl group between the phenol nucleus and the phenol nucleus, and is excellent in heat resistance. By making the content of the aralkyl-modified phenolic resin at least 50% by weight of the total amount of the binder, the amount of gas generated at high temperature can be reduced, and the sticking phenomenon can be suppressed.

Examples of the binding material other than the aralkyl-modified phenol resin include various elastomer-modified phenol resins in which phenol resin and phenol resin are modified with cashew oil, silicone oil and various elastomers, various elastomer-dispersed phenol resins in which various elastomers and fluoropolymers are dispersed in phenol resin A thermosetting resin such as a resin, an epoxy resin, and a benzoxazine resin can be used.

In order to improve moldability, it is preferable to use a phenol resin having a weight average molecular weight of 2,000 to 5,000 as the remainder, with the content of the aralkyl-modified phenolic resin being 80% by weight or less of the total weight of the binder.

The friction material of the disc brake pad of the present invention is an abrasive which contains inorganic particles having a Mohs hardness of 6 to 8 and an average particle size of 10 to 200 占 퐉 in an amount of 1 to 3% by weight based on the total amount of the friction material.

If the Mohs hardness of the inorganic particles is less than 6, the sufficient effect can not be obtained and the fade resistance lowers. If the Mohs hardness of the inorganic particles is 8 or more, the aggressiveness of the surface is increased and the amount of grinding flour of the disk rotor is increased. The relative resigning phenomenon is likely to occur and the amount of wear of the disk rotor is increased. As the inorganic particles having a Mohs hardness of 6 to 8, inorganic particles usually used for friction materials such as zirconium oxide, zirconium silicate, and aluminum oxide can be used.

In the present invention, the Mohs hardness is 1: talc, 2: gypsum, 3: calcite, 4: fluorspar, 5: apatite, 6: quartz, 7: quartz, "Old Mohs hardness" is applied.

If the average particle diameter is less than 10 mu m, the sufficient effect can not be obtained and the fade resistance is decreased. If the average particle diameter is 200 mu m or more, the surface aggressiveness is increased and the amount of grinding flour of the disk rotor is increased. Sticking phenomenon is likely to occur, and the amount of wear of the disk rotor is increased. In the present invention, a numerical value of 50% particle diameter measured by a laser diffraction particle size distribution method was used as an average particle diameter.

If the content of the inorganic particles is less than 1% by weight based on the total amount of the friction material, the sufficient effect can not be obtained and the fade resistance lowers. If the content of the inorganic particles is 3% by weight or more relative to the entire friction material, The amount of grinding dust generated by the grinding wheel is increased, so that the relative sticking phenomenon is likely to occur and the amount of wear of the disk rotor is increased.

The friction material of the disk brake pads of the present invention preferably further contains a titanate of an alkali metal and / or an alkaline earth metal in an amount of 20 to 30% by weight based on the total amount of the friction material. It is possible to suppress the grinding powder of the disk rotor from adhering to the surface of the friction material as an iron film by adding an appropriate amount of an alkali metal and / or alkaline earth metal titanate which is likely to form a film on the surface of the disk rotor, The suppression effect of the phenomenon becomes remarkable. If the addition amount is excessive, the abrasion resistance is deteriorated.

The titanate of the alkali metal and / or alkaline earth metal is preferably a plate-like or scaly shape which tends to form a film on the surface of the disk rotor. As the titanate of the alkali metal and / or alkaline earth metal, potassium titanate, lithium potassium titanate, potassium titanate magnesium and the like which are usually used for the friction material can be used.

The friction material of the disc brake pad of the present invention preferably further contains the cashew dust in an amount of 3 to 5% by weight based on the total amount of the friction material. By adding an appropriate amount of cashew dust which is likely to be oxidized at a high temperature, the oxidation of the fine iron component on the surface of the friction material can be inhibited, and the effect of suppressing the sticking phenomenon becomes remarkable. If the addition amount is excessive, the fade resistance decreases.

Further, the friction material of the disc brake pad of the present invention may be a friction material such as a metal fiber, an organic fiber, an inorganic fiber or the like used for a friction material in addition to the above-mentioned binder, grinding material, titanate of an alkali metal and / A fibrous base material, an organic filler, an inorganic filler, a lubricant, and a metal particle.

Examples of the fiber substrate include metal fibers such as iron fibers, steel fibers, copper fibers, brass fibers, bronze fibers, aluminum fibers and zinc fibers, organic fibers such as aramid fibers and acrylic fibers, And inorganic fibers such as fibers, rock wool, and potassium titanate fibers.

Examples of the friction and wear adjusting agent include rubber dusts (crushing components of tire tread rubber), various rubber particles of unvulcanized rubber, various fillers such as vulcanized rubber particles, calcium carbonate, barium sulfate, calcium hydroxide, vermiculite And mica; graphite, cokes, molybdenum disulfide, tin sulfide, zinc sulfide, and iron sulfide; metal particles such as copper particles, brass particles, zinc particles, aluminum particles and the like.

These fibrous base materials and friction / wear adjustment materials can be suitably used in combination according to the intended quality, mechanical properties, and frictional wear characteristics.

The disk brake pads of the present invention are prepared by uniformly mixing the binder, grinding material, titanate, alkali metal and / or alkaline earth metal titanate, cashew dust, fiber substrate, and friction / wear adjuster mixed in a predetermined amount using a mixer Mixing process; A heating / press-molding step of putting a metal back plate, such as steel, which has been subjected to cleaning and surface treatment in advance and coated with an adhesive, into a thermoforming mold and heating / pressurizing the molded product; A heat treatment step of heating to complete the curing reaction of the binder; And a polishing process for forming a friction surface. A preliminary molding process for preliminarily molding the granules obtained in the friction material mixture or the granulation process with a preliminary molding die is carried out, if necessary, before the heating / pressurizing process, , A heating / press molding process, a coating process, and a scorching process are performed.

[Example]

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1 to 10: Table 1 and Comparative Examples 1 to 9: Table 2) were mixed with a Loedige mixer for 10 minutes, , And the resulting friction material mixture was charged into a preformed mold and pressurized at 35 MPa for 1 minute to preform. This preform and a back plate made of steel, which had been subjected to cleaning and surface treatment in advance and coated with an adhesive, were put on a thermoforming mold in a superposed state and heated / pressed under the conditions of a molding temperature of 155 캜 and a molding pressure of 40 MPa for 5 minutes , And then subjected to heat treatment (curing) at 200 캜 for 4 hours in a heat treatment furnace, followed by painting, baking (heating and drying) and polishing to prepare disk brake pads for passenger cars of Examples and Comparative Examples.

Evaluation tests on sticking, fade resistance, abrasion resistance and moldability were conducted on the disc brake pads of the examples and comparative examples. Evaluation methods and evaluation criteria are shown in Tables 3 and 4.

From the results shown in Tables 1 and 2, when the amount of the binder, the content of the aralkyl-modified phenol resin, the Mohs hardness, the average particle diameter and the content of the inorganic particles serving as the abrasive to be incorporated are within the ranges specified in the present invention, It can be seen that it is highly evaluated for the properties, abrasion resistance, and moldability.

As described above, according to the present invention, it is possible to provide a brake pad having good fade resistance, abrasion resistance, and moldability while effectively suppressing occurrence of a sticking phenomenon. It is possible to cope with the miniaturization and weight reduction of brake component parts which have been demanded in recent years, contributes to improvement of fuel economy and operability of the vehicle, and is very practical.

1: Disc brake pad (friction member)
2: back plate
3: friction material

Claims (3)

1. A disc brake pad for use in a disc brake comprising a disc rotor made of an iron-based material, wherein the friction material comprises a friction material containing a fiber base material, a binder, a grinding material and a friction / wear adjustment material, By weight of an aralkyl-modified phenol resin, 50 to 80% by weight of an aralkyl-modified phenol resin as a remaining part of the aralkyl-modified phenol resin, and a phenol resin having a weight-average molecular weight of 2,000 to 5,000 And an inorganic particle having a Mohs hardness of 6 to 8 and an average particle diameter of 10 to 200 占 퐉 in an amount of 1 to 3% by weight based on the whole amount of the friction material. The method according to claim 1,
Wherein the friction material contains a titanate of an alkali metal and / or an alkaline earth metal in an amount of 20 to 30% by weight based on the total amount of the friction material. 3. The method according to claim 1 or 2,
Wherein the friction material contains 3 to 5 wt% of cashew dust in relation to the total amount of friction materials.

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