KR100376335B1 - Friction material of continuous tire rubber forming phase and its manufacturing method - Google Patents

Abstract

The present invention provides a friction material produced by using waste tires and a method for manufacturing the same, and pretreatment of the vulcanized waste tires is obtained by mixing a potassium titanate and a friction stabilizer to form a rubber mixture to form a rubber continuous phase. The rubber mixture further comprises additives produced by sulfur, morpholinobenzothiazol, diphenyl and nidine, hexamethylenetetramine or tetramethylthiuram disulfide, zinc oxide or a suitable combination of manganese oxide and stearic acid. As a result, a friction material which is harmless to the human body and an economical method of manufacturing the same are obtained.

Description

Friction material of continuous tire rubber forming phase and its manufacturing method {.}

The present invention relates to a friction material manufactured by using waste tires, and more particularly, by mixing waste tire rubber powder with potassium titanate and a friction stabilizer using waste tires that are disposed of as waste, and heating and compressing them to form a plate. Then, the waste tire rubber forms a continuous phase in the molding, and the molding relates to a technique used as a friction material.

Waste rubber, particularly waste tires, has recently emerged as a global environmental pollutant. In terms of recycling of resources, research on the use of waste tires has been conducted steadily, but there are not many suitable uses. Until now, waste tires have been used as buffers for ships, as finely pulverized as possible, mixed with plastics, or incinerated to be used as heat sources (Korean Patent Publication 82-665).

However, according to the treatment method used for incineration as a heat source, although the primary pollution problem of the waste tires currently faced can be solved, it is not a desirable solution in the future. Because incineration of waste tires as a heat source, there is a problem that not only odor is generated, but also harmful gases such as SO ₂ , NO ₂ , and Cl ₂ , which are secondary pollutants, increase in air pollution.

Friction materials are brake linings, disc pads, clutch facings, wheelsets, etc., which are directly connected to the safety of automobiles, airplanes, trains, industrial machines, etc., and use the frictional resistance generated by mechanical contact to perform power braking and transmission. It converts kinetic energy into thermal energy and absorbs heat to gradually release heat to the outside to control the deceleration or acceleration of the car.

Automotive friction material, which is the most used friction material, is mainly manufactured by adding asbestos to phenol resin or epoxy resin. Therefore, in the conventional automotive friction material, the resin forms a continuous phase.

Asbestos is an inorganic fiber in which both short and long fibers coexist, and it has been widely used because it is inexpensive and suitable for automobile brakes because of its heat resistance, friction and hardness, which are main characteristics as friction materials.

However, asbestos is known to be harmful to human respiratory system due to dust generation during use. That is, asbestos dust is known to act as an accelerator for the action of other carcinogenic substances. Since suspicion of carcinogens has been pointed out, there is a tendency to tighten regulations to prohibit the use of asbestos, so research into alternative materials has attracted worldwide attention.

The United States banned the use of asbestos in 1996 and banned its use as a friction material for automobiles as of 1991. Sweden banned asbestos products in 1987 and West Germany in January 1988.

In Korea, new car models are also regulated from January 1, 1992 on the use of asbestos for brake linings, pads and clutch facings for automobiles in accordance with the notice of the Environment Agency No. 3317-11-11528 (November 9, 1989). It is regulated from January 1, 94. 1, and existing cars are regulated from January 1, 93. 1 and large vehicles from 9 January 1. This trend is expanding in other countries, and as a result, as a result, as well as the manufacturers side, as well as the consumer side is greatly influenced by consumers, the development of countermeasures, especially asbestos substitutes, is at an urgent time.

It is an object of the present invention to manufacture new and environmentally friendly friction materials by reusing waste tires to add value and replacing asbestos, a carcinogen, with harmless inorganic fibers.

Accordingly, the rubber concrete composition is prepared according to the rubber concrete manufacturing method (Korean Patent 121839, 212040 and US Patent 5621037) owned by the applicant, and the applicant has synthesized potassium titanate fiber (whisker) and It is to provide a manufacturing method for producing a friction material of a desired shape by mixing, heating, and compressing a friction stabilizer. The characteristic of this friction material is that in the internal structure, the resin (mainly phenol resin) forms a continuous phase in the existing friction material, whereas the waste tire rubber forms a continuous phase.In terms of mechanical properties, the waste tire rubber has a suitable friction property. To provide.

1 shows a photograph of a synthesized potassium titanate whisker with an electron microscope.

2 is a graph showing an X-ray diffraction curve of the synthesized potassium titanate.

In the friction material prepared in the present invention, the waste tire is pulverized into 10 to 30 mesh, mixed with rosin oil, and put into an autoclave and pretreated at a pressure of about 150 to 170 psi and a temperature of about 100 to 150 ° C.

The friction material of the present invention can be produced by mixing and molding the pretreated waste rubber with potassium titanate fiber and a friction stabilizer.

Preferably, the friction material further comprises additives of the composition by suitable combinations of sulfur, morpholinobenzothiazole, diphenyl and nidine, hexamethylenetetramine or tetramethylthiuram disulfide, zinc oxide or manganese oxide and stearic acid. Can be.

That is, after mixing the pre-treated waste rubber with potassium titanate fiber and friction stabilizer, and molding at a temperature of about 120 to 150 ℃ and a pressure of about 50 to 100kg / cm ² , the pre-treated rubber is cross-linked, waste tire rubber is continuous The friction material forming the phase can be obtained.

In this case, the friction material may be obtained by molding only the pretreated rubber and the friction stabilizer without adding potassium titanate fiber, and the friction material thus manufactured is also included in the scope of the present invention. do. However, this example does not limit the scope of the present invention.

Example

<Synthesis process>

Take 25g and 83g of potassium carbonate (K ₂ CO ₃ ) and titanium dioxide (TiO ₂ ), respectively, mix them with ethyl alcohol and grind for about 20 hours. Put it in a container and evaporate ethyl alcohol in a dry oven (200 ℃) for about 24 hours to obtain a very fine powder, put this powder in a reactor (about 1000 ℃) and react for about 20 hours to make potassium titanate (K ₂ Ti ₆ O ₁₃ ) 100 g of whiskers were obtained. Fig. 1 is a photograph of the obtained potassium titanate whisker with an electron microscope, the whisker having a length of approximately 5 to 8 mu m and a diameter of 0.1 to 0.2 mu m.

2 shows the structure of the obtained potassium titanate by X-ray imaging.

<Pretreatment process>

Waste tire powder (provided by Korea Resources Recycling Corporation) crushed to a size of 10 to 30 mesh is mixed with rosin oil and placed in an autoclave and treated for 30 minutes to 1 hour under a pressure of 150 to 170 psi and a temperature of 100 to 150 ° C. Pretreated waste rubber was obtained.

<Mixing process>

5 to 50 parts by weight of sulfur, 5 to 10 parts by weight of morpholinobenzothiazol, 3 to 5 parts by weight of zinc oxide, 3 to 5 parts by weight of stearic acid, 0 to 10 parts by weight of potassium titanate, based on 100 parts by weight of pretreated rubber, and As a friction stabilizer, 10 to 20 parts by weight of cashew nut oil (Samjeon Pure Chemical Products) is added to form a rubber mixture.

<Molding process>

The composition was poured into square castings each 25 mm long and 6 mm high, and then chopped well with a small vibrator for about 5 minutes and then about 10 minutes at a pressure of about 100 kg / cm ² and a temperature of about 140 ° C. During compression molding to produce a friction material.

<Friction material characteristic>

Hardness test

According to the Korean Industrial Standard (KS R 1072), Rohr's hardness of the prepared friction material was measured. The value recorded 3.89. Basically, the hardness of the friction material is very excellent, noting that the loss hardness of the friction material should be between 3.80 and 3.98 in consideration of the loss hardness of iron, which is a component of the brake wheel.

Friction test

According to Korean Industrial Standard (KS R 4024), the friction performance (wear rate and coefficient of friction) of one kind of friction material (for drum brakes) produced in a friction tester was measured. The test temperature was 100 ℃, 150 ℃ and 200 ℃ and the friction coefficient and wear rate at each test temperature were calculated as follows.

Coefficient of friction (μ) = f / F

f: frictional force (N)

F: total compressive force applied to the test piece (N)

Wear rate = (1 / 2πR) (A / n) [(d ₁ -d ₂ ) / f _m ]

R: Distance between the specimen center and the rotation axis center (150mm)

A: Total area of friction surface of test piece (mm ² )

n: total rotational speed of the disc during the test

d ₁ : average thickness of the test piece before the test (6 mm)

d ₂ : average thickness of the test piece after the test (mm)

f _m : Average friction at test (N)

Table 1 below is the friction performance test results of the friction material obtained in the present invention.

The above figures indicate that the frictional performance of the friction material obtained in the present invention is excellent compared to Table 2 (Korean Industrial Standard) below.

As described above, the present invention is to produce a new friction material in which waste tire rubber forms a continuous phase by recycling waste tires, which are one of the wastes increasing in recent years. Therefore, waste tires that are high in value can be made high, and the domestic friction material manufacturing method is a technology that all of them buy expensive foreign materials, so that the manufacturing method and technology of the present invention can reduce the manufacturing cost and produce cost. It will be cheap and you will have a global price competitiveness.

Claims (7)

A friction material obtained by molding a rubber mixture by mixing pretreated waste tire rubber with potassium titanate and a friction stabilizer, wherein the pretreated waste tire rubber forms a continuous phase. delete delete delete The method of manufacturing a friction material according to claim 1, which has the following friction performance. Friction Coefficient: 0.3 ~ 0.6 Wear rate: 0.86 to 2.92 delete A friction material produced using the method of claim 1.