KR100765638B1 - Environmental friendly double-layer composition for automotive friction materials and its preparing method - Google Patents

Abstract

The present invention relates to a double material composition for an environmentally friendly brake friction material and a method of manufacturing the same, wherein the double material for the brake friction material excludes the use of inhalable fine ceramic fibers known as carcinogens, and instead, the alkali oxide and alkaline earth metal components are 18% by weight. By using the reinforcing fibers as a mixture of aramid fibers, iron fibers, mineral fibers, slag wool (slag wool) added as described above, the present invention relates to a double material composition for environmentally friendly brake friction material satisfying the international environmental standards and a method for producing the same.

To this end, the present invention is a reinforcing fiber composed of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, 8.5% by weight of binder, solid A composite comprising 12 wt% lubricant, 2 wt% abrasive, 35 wt% filler and 8 wt% friction modifier was thermoformed at a temperature of 70-110 ° C. and a pressure of 80-120 MPa for 1-2 minutes, followed by 200 The heat treatment is performed for 5 hours at ˜300 ° C., and the scorch is prepared for 2 to 4 minutes at a temperature of 450 to 550 ° C.

Eco-Friendly, Brake, Friction Material, Double Material, Reinforcing Fiber, Mineral Fiber

Description

Environmental friendly double-layer composition for automotive friction materials and its preparing method}

1 is a schematic view showing the structure of a general brake friction material,

2 is a scanning electron micrograph of the mineral fiber used in the present invention,

3 is a scanning electron micrograph of a ceramic fiber conventionally used.

<Explanation of symbols for main parts of the drawings>

100: friction material 110: upper layer material

120: double material 130: adhesive layer

140: rear panel 150: noise reduction shim

The present invention relates to a double material composition for environmentally friendly brake friction materials used in drum linings or brake pads mounted on an automobile brake system, and a method of manufacturing the same. More specifically, aramid having an alkali oxide and an alkaline earth metal component added at least 18% by weight. By using a reinforcing fiber as a mixture of fibers, iron fibers, mineral fibers, slag wool (slag wool), the present invention relates to a double material composition for environmentally friendly brake friction material and a method of manufacturing the same satisfying international environmental standards.

In general, the braking force is one of the most important factors among the functions of the vehicle, the brake friction material in the braking force is showing a large difference depending on the state, the brake friction material used for braking of the vehicle is a binder, reinforced fiber , A multiphase composite material composed of an abrasive, a solid lubricant, a filler, and the like, and generally contains 10 or more kinds of raw materials.

The dual material for the brake friction material is located between the upper layer material 110 and the rear plate 140 of the friction material 100, as shown in Figure 1, is used for the purpose of improving heat resistance and adhesion.

The double member 120 may also include 10 or more kinds of raw materials such as binders, reinforcing fibers, abrasives, solid lubricants, fillers, and the like, as the upper layer 110 of the friction material 100.

By the way, as shown in Figure 3, the conventional double material, it was common to use a refractory ceramic fiber having a constant composition ratio as a reinforcing fiber to improve heat resistance, but as the inhalable fine ceramic fiber is known as a carcinogenic material North America Through the environmental regulations (CAL Prop 65) and the European environmental regulations (EU 2001/41 / EC) of fire-resistant ceramic fibers containing up to 18% by weight of alkali oxides (Na ₂ O + K ₂ O + CaO + MgO + BaO) The use is gradually banned.

In particular, these ceramic fibers are mostly inhalable microfibers having a diameter of 2.5 to 3 microns, and proved to be harmful to humans that may cause lung cancer of friction material manufacturers, and thus, development of dual materials using replacement fibers is urgently needed.

Therefore, the present invention has been invented to solve the above problems, while replacing the inhalable fine ceramic fibers of carcinogen with mineral fibers while maintaining the physical properties and heat resistance properties to be provided as a double material, aramid fibers, iron fibers, slag wool The object of the present invention is to provide a double material for brake friction material that satisfies international environmental standards by optimizing the relative composition ratio of reinforcing fibers composed of (slag wool).

To this end, the present invention is a reinforcing fiber composed of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, 8.5% by weight of binder, solid A composite comprising 12 wt% lubricant, 2 wt% abrasive, 35 wt% filler and 8 wt% friction modifier was thermoformed at a temperature of 70-110 ° C. and a pressure of 80-120 MPa for 1-2 minutes, followed by 200 The heat treatment is performed for 5 hours at ˜300 ° C., and the scorch is prepared for 2 to 4 minutes at a temperature of 450 to 550 ° C.

Hereinafter, the features of the present invention for achieving the above object are as follows.

Double material composition for environmentally friendly brake friction material according to the present invention is a reinforcing fiber composed of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, A composite material comprising 8.5 wt% binder, 12 wt% solid lubricant, 2 wt% abrasive, 35 wt% filler, and 8 wt% friction modifier.

In addition, the manufacturing method of the double material for the environmentally friendly brake friction material, the reinforcing fiber composed of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, A composite material comprising 8.5 wt% binder, 12 wt% solid lubricant, 2 wt% abrasive, 35 wt% filler, and 8 wt% friction modifier for 1 to 2 minutes at a temperature of 70 to 110 ° C. and a pressure of 80 to 120 MPa After thermoforming, heat treatment was performed at 200 to 300 ° C. for 5 hours, and then prepared by scorching at a temperature of 450 to 550 ° C. for 2 to 4 minutes.

Hereinafter, a double material composition for an environmentally friendly brake friction material according to the present invention and a manufacturing method thereof will be described in detail.

Reinforcement fiber consisting of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, 8.5% by weight of binder, 12% by weight of solid lubricant, It is characterized by consisting of a composite material comprising 2% by weight of abrasive, 35% by weight of filler, 8% by weight of friction modifier.

The reason for the numerical limitation on the component content of such a double member is as follows.

1) 3% by weight of aramid fiber

Aramid fiber is a representative organic reinforcing fiber added to the friction material, it is used to increase the strength of the preform, and to improve the stability and wear resistance of the friction coefficient.

When the content of the aramid fiber is out of the content, the reinforcing effect with the binder is reduced to reduce the strength of the friction material, and there is a problem that extra reinforcing fibers not shared with the binder can be easily dropped at high temperatures, which is not preferable. .

2) 25% by weight of iron fiber

Iron fiber is a metal fiber that is roughly distinguished from organic fiber, and is used to improve wear resistance, thermal conductivity and reinforcement performance of friction materials. In particular, iron fibers exhibit very good properties in terms of high temperature braking force loss and braking force recovery.

When the content of the iron fiber is out of the content, the high temperature braking force is decreased, and the wear of the disk is accelerated due to the adhesion phenomenon with the counterpart disc, and the increase of the occurrence frequency of the braking noise is not preferable.

3) 1.5 wt% mineral fiber

Mineral fiber has a shape as shown in Figure 2, as a reinforcing fiber to replace the ceramic fiber, it is used to improve the stability and strength of the high temperature friction coefficient.

When the content of the mineral fiber is out of the content, the heat resistance characteristic of the friction material is reduced, and there is a problem that the excess mineral fiber which hardly affects the reinforcing effect may cause braking noise.

4) 5% by weight slag wool

Slag wool is a kind of ceramic fiber and is used to improve the heat resistance of the friction material like mineral fiber.

When the content of the slag wool is out of the content, the stability of the high temperature friction coefficient is inhibited, and there is a problem that may cause braking noise, which is not preferable.

Among the reinforcing fibers according to the present invention, in particular, mineral fibers are excellent in high temperature heat resistance as in the conventional ceramic fibers, but 35 to 45% by weight of quartz (SiO ₂ ), 20 to 25% by weight of alumina (Al ₂ O ₃ ), Alkali having a content of 15 to 20% by weight of calcium oxide (CaO), 5 to 10% by weight of magnesium oxide (MgO) and other trace metals (for example, known mineral fibers such as TiO ₂ or Fe) Oxides and alkaline earth metals (Na ₂ O + K ₂ O + CaO + MgO + BaO) contain at least 18% by weight.

It is an environmentally friendly composition that meets international environmental standards.

Meanwhile, the binder contains a binder, a solid lubricant, an abrasive, a filler, and a friction modifier in the reinforcing fiber, and the binder may be a component generally used in a resin composition. In the present invention, as a phenol resin, a member of a friction material It is used to increase the strength and thermal stability of the friction material by performing the role of bonding to each other. In particular, when the binder is thermally decomposed at high temperature braking, a loss of frictional force (fade) is exhibited. Therefore, a heat resistant phenol resin having increased crosslink density is used for the friction material.

When the content of the binder exceeds 8.5% by weight, the bonding force to the member of the friction material is reduced, thereby reducing the strength of the friction material, and it is not preferable because there is a problem that can reduce the high temperature braking force by the unbonded phenol resin.

In addition, the solid lubricant is a mixture of zinc sulfide, graphite, coke, is used to improve the stability, wear resistance and noise characteristics of the friction coefficient according to the braking temperature.

When the content of the solid lubricant is out of 12% by weight, it is not preferable because there is a problem of inhibiting the stability of the friction coefficient and causing a decrease in braking force due to the decrease of the friction coefficient.

In addition, the abrasive is alumina, and serves to control the friction and to remove the heat-modified friction film of the rotor surface.

If the content of the abrasive is more than 2% by weight, it is not preferable because the surface attack resistance to the disk is increased to increase the wear rate of the counterpart disk, increase the torque amplitude and increase the frequency of noise.

In addition, the filler is a mixture of barium sulfate and calcium hydroxide, in case of barium sulfate is used to increase the density of the friction material as an inert material, and in the case of calcium hydroxide to control the acidity of the friction material.

If the content of the filler is more than 35% by weight, the friction material density is reduced and wear resistance is impaired, and the excess filler component is unbound with the binder, which is not preferable because of the problem of easily falling off from the surface of the friction material.

In addition, the friction regulator is a rubber powder, is used to adjust the coefficient of friction by promoting the lubricity of the friction material.

When the content of the friction regulator is more than 8% by weight, it is undesirable because there is a problem that inhibits the noise characteristics, decreases the coefficient of friction and inhibits the high temperature braking characteristics.

Referring to the method of manufacturing a double material for an environmentally friendly brake friction material of the present invention with such a composition as follows.

The composite material having the composition described above is thermoformed at a temperature of 70 to 110 ° C. and a pressure of 80 to 120 MPa for 1 to 2 minutes, and then heat treated at 200 to 300 ° C. for 5 hours and at a temperature of 450 to 550 ° C. It is prepared by scouring for 2 to 4 minutes.

At this time, if the thermoforming temperature is less than 70 ℃ hardening by the binder is not made, if it exceeds 110 ℃ over-hardening of the binder is made to reduce the bonding strength.

In addition, if the thermoforming pressure is less than 50MPa, the molding density of the friction material is reduced, and if it exceeds 120MPa, the desired compression ratio and porosity of the friction material cannot be obtained.

In addition, if the thermoforming time is less than 1 minute, the flow of the binder is not sufficient, and sufficient curing is not achieved. If the thermoforming time exceeds 2 minutes, the bond strength is reduced by over curing.

In addition, if the heat treatment temperature is less than 200 ℃ can not obtain a uniform curing state, if it exceeds 300 ℃ overheating may be a member heat deformation.

In addition, when the heat treatment time is less than 5 hours, complete curing is not performed.

In addition, if the scorch temperature is less than 450 ℃ can not supply sufficient thermal history to the friction material surface, if it exceeds 550 ℃ it may inhibit the friction characteristics by the excessive thermal history.

In addition, when the scorch time is less than 2 minutes, it is impossible to uniformly supply the heat history to the entire surface of the friction material. When the scorch time exceeds 4 minutes, the friction property may be inhibited by the excessive heat history.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The following examples are only intended to illustrate the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

Example, Comparative Example

Each component was mix | blended with the composition shown in Table 1, and it mixed uniformly in the lodge mixer at 2000 rpm or more.

Each mixture was thermoformed at a temperature of 90 ° C. and a pressure of 100 MPa for 1 minute, followed by heat treatment at 250 ° C. for 5 hours.

After heat treatment, the mixture was scorched at a temperature of 500 ° C. for 3 minutes to obtain Examples and Comparative Examples.

Test Example

Physical properties (hardness, compression amount, specific gravity, shear strength, porosity) and brake dynamo-alpine test were performed on the friction materials prepared in Examples and Comparative Examples, and the results are shown in Table 2 below.

(1) Property test

The physical property test was carried out to compare and evaluate the physical properties of the friction material prepared in Examples and Comparative Examples.

Hardness, compression, specific gravity, shear strength and porosity were measured according to Korean Industrial Standard (KS R 0080).

(2) brake dynamo alpine test

Alpine test is an internationally assessed test method that evaluates deterioration performance due to fade (loss of friction due to thermal history) about 15km of continuous curve from the top of the European Alps to the toll gate and downhill road. .

 In this test, the brake fluid temperature during braking was measured to compare and evaluate the thermal barrier effect as a double material for the friction materials prepared in Examples and Comparative Examples.

As can be seen from the above results, the physical property test results show that the physical properties of the comparative example of the double member using the conventional ceramic fiber and the embodiment of the double member using the mineral fiber as a substitute are very similar.

As a result of the brake dynamo-alpine test, it was confirmed that the temperature of the maximum brake fluid of the comparative example and the example showed similar heat shielding characteristics to the double member using the conventional ceramic fiber.

As described above, the dual material composition for eco-friendly brake friction material and the method of manufacturing the same according to the present invention exclude mineral fiber, aramid fiber, in which alkali oxide and alkaline earth metal components are added at least 18% by weight, excluding inhalable fine ceramic fibers as carcinogens. It is composed of iron fiber and slag wool, which is an optimal reinforcing fiber, which satisfies the international environmental standard, and has the effect of maintaining the physical and heat resistance properties to be provided as a double material.

Claims (8)

Reinforcement fiber consisting of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, 8.5% by weight of binder, 12% by weight of solid lubricant, Eco-friendly brake friction material comprising a composite material comprising 2% by weight of abrasive, 35% by weight of filler, 8% by weight of friction modifier. delete The method according to claim 1, The binder is an eco-friendly brake friction material, characterized in that the phenolic resin. The method according to claim 1, The solid lubricant is a double material composition for environmentally friendly brake friction material, characterized in that the mixture of zinc sulfide, graphite, coke. The method according to claim 1, The abrasive material is an environmentally friendly double friction composition for brake friction material, characterized in that the alumina. The method according to claim 1, The filler is a double material composition for environmentally friendly brake friction material, characterized in that the mixture of barium sulfate, calcium hydroxide. The method according to claim 1, The friction modifier is a double material composition for environmentally friendly brake friction material, characterized in that the rubber powder. Reinforcement fiber consisting of 3% by weight of aramid fiber, 25% by weight of iron fiber, 1.5% by weight of mineral fiber, 5% by weight of slag wool, 8.5% by weight of binder, 12% by weight of solid lubricant, A composite material comprising 2 wt% abrasive, 35 wt% filler, and 8 wt% friction modifier was thermoformed for 1 to 2 minutes at a temperature of 70 to 110 ° C. and a pressure of 80 to 120 MPa, followed by 5 at 200 to 300 ° C. Method of producing a double material for environmentally friendly brake friction material, characterized in that by performing a heat treatment for a time and scorch for 2 to 4 minutes at a temperature of 450 ~ 550 ℃.

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