KR20100073773A - A non-steel type friction material and a brake for vehicle comprising the non-steel type friction material - Google Patents

Abstract

PURPOSE: A non-steel friction material and a vehicle brake including the same are provided to reduce manufacturing costs by using not only modified phenol resin but also commercial phenol resin as binder. CONSTITUTION: A non-steel friction material comprises a solid lubricant whose volume percentage is 12-14% and an abrasive material whose volume percentage is 14-16%. The solid lubricant comprises graphite, antimonous sulphide or the mixture of the same. The abrasive material comprises zircon, muscovitum, triiron, tetraoxide, or the mixture of the same. The friction material includes textile material, binder, filler, and friction modifier. The volume percentage of the binder is 16-18%. The volume percentage of the filler is 6-10%. The Volume percentage of the friction modifier is 18-20%.

Description

A non-steel type friction material and a brake for vehicle comprising the non-steel type friction material}

The present invention relates to a non-steel friction material, and more particularly, to a non-steel friction material and a brake including the improved braking property and resistance to fade.

A brake friction material is a function of decelerating, braking, and clutching wheel or machine operation by frictional force on the surface (drum or disk) that faces the friction material, and generates kinetic (driving) energy due to friction. It means the device which converts into heat energy.

In the early 1900s, these friction materials were first made of woven fabrics made by impregnating cotton or asphalt with cotton fabrics, and since 1906, brake friction materials (linings) mainly composed of asbestos, which has excellent thermal safety, Was used for the first time in the braking system, and in 1960, when a phenol resin was developed, a friction mold-based friction material began to be produced in earnest from 1960.

Asbestos was identified as a carcinogen by the US Environmental Protection Agency (EPA) in the late 1980's, as a result of the regulation of various products, asbestos-based friction materials began to be developed. Has been steadily developed around non-steel friction materials that do not contain steel fibers and low-steel friction materials that contain steel fibers.

The use range of such friction materials is widely used in industrial machines, railway wheels, aircrafts, ships, etc., mainly in automobiles.

Friction material for automobile brake is generally composed of about 8 ~ 20 kinds of different raw materials, and its components are divided into about 6 kinds. In general, the components of friction material are matrix and binder. , Fillers, abrasives, lubricants, friction modifiers, and the like.

Each of these constituent materials is added in an appropriate amount to obtain the friction characteristics required for automobile braking, and it is common practice that the type and content of the constituent materials used are generally not disclosed as the know-how of the friction material producer.

The friction characteristics required for braking of the vehicle are largely classified into stability and durability, and the stability is determined by friction coefficient, stability of friction coefficient, fade and recovery, mechanical strength, and the like. It is determined by relative surface damage and unpleasantness.

These frictional properties are determined by the raw materials of the friction material components, their composition ratios and mixing methods, and subsequent manufacturing processes.

The raw material of the friction material component is to examine the properties of the raw material, such as strength, hardness, melting point to screen the material to meet each role, size, surface treatment, density, etc. also affect the selection criteria. The compositional blending ratio varies with the fraction between the components. The friction material manufacturing process is carried out in the order of material weighing, mixing of materials, pre-form, hot-press molding, and post-curing process, and then the surface pressure, processing temperature and processing time of the molding process. Accordingly the friction characteristics can be adjusted.

On the other hand, the friction material containing the steel fiber of the fiber (fiber) serving as a substrate of the friction material components are commonly referred to as low-steel type brake lining (friction material that does not contain steel fiber) Is called non-steel type brake lining.

Among them, non-steel brake friction materials have good braking force and aggression against disks, but have a weaker mechanical strength than other friction materials.

As an example of the prior art for solving such drawbacks, there was a non-steel brake friction material using alumina as a friction regulator, but there is a disadvantage in that the manufacturing cost is high using a strain-based phenol resin as a binder, and the amount of wear is still satisfactory. When braking during high-speed driving, the friction energy is mostly converted to heat, which increases the temperature of the friction material and the disk, causing the friction coefficient to drop, and the temperature coefficient after cooling to the room temperature. There was a problem in the recovery phenomenon.

Accordingly, the first problem to be solved by the present invention is to provide a non-steel friction material with improved braking characteristics and resistance to fade.

The second problem to be solved by the present invention is to provide a vehicle brake including the non-steel friction material.

In order to achieve the first object of the present invention,

A non-steel based friction material comprising 12 to 14 volume percent solid lubricant and 14 to 16 volume percent abrasive is provided.

According to one embodiment of the invention, the solid lubricant may be graphite, antimony trisulfide or mixtures thereof.

According to another embodiment of the present invention, the abrasive may be zircon silicate, mica, triiron tetraoxide or mixtures thereof.

According to another embodiment of the present invention, the non-steel friction material may further include a fiber base, a binder, a filler and a friction control agent.

According to another embodiment of the present invention, the volume percentage of the binder may be 16-18.

According to another embodiment of the present invention, the volume% of the filler may be 5 to 10.

According to another embodiment of the present invention, the volume percentage of the friction modifier may be 18 to 20.

According to another embodiment of the present invention, the binder may be a commercial phenol resin or a modified phenolic resin.

According to another embodiment of the present invention, the fiber base may be an organic fiber, a ceramic fiber, a bronze fiber or a mixture thereof.

According to another embodiment of the invention, the friction modifier may be cashew dust, tire rubber or mixtures thereof.

According to another embodiment of the present invention, the filler may be calcium hydroxide, barite or mixtures thereof.

The present invention provides a vehicle brake including the non-steel friction material in order to solve the second problem.

The non-steel friction material according to the present invention is controlled by adjusting the relative amounts of the abrasive and the solid lubricant, and is stable due to the small change in the friction coefficient according to the speed and the braking deceleration, and has excellent resistance to fading and improved wear resistance. In terms of efficacy can be excellent. In addition, the non-steel friction material according to the present invention can use a commercial phenol resin as well as the modified phenol resin as a binder has the effect of reducing the manufacturing cost. Therefore, the non-steel friction material according to the present invention will provide a significant advantage to the technical field to which the present invention belongs.

Among the components of the friction material, the solid lubricant and the abrasive have the greatest influence on the friction coefficient during braking, the friction characteristics at high temperature and high pressure, the aggressiveness and the amount of wear. In particular, the relative amounts of solid lubricant and abrasive have a great influence on the friction properties.

The coefficient of friction during braking of automobiles varies with braking pressure, the rotor temperature, the rotational speed of the rotor and humidity. However, in order to show excellent braking ability, stable friction coefficient should be obtained by adjusting the relative amount of the components of the friction material so that the friction coefficient does not change even under various braking conditions.

Finding the relative amount of the components of the friction material exhibiting the stable friction coefficient is the most important concern in the technical field to which the friction material belongs.

Thus, the present inventors conducted research and tests on the relative amounts of the components of the non-steel friction material exhibiting the best friction characteristics, and completed the present invention based on the results.

The non-steel friction material according to the present invention is characterized in that it comprises 12 to 14% by volume of the solid lubricant and 14 to 16% by volume of the abrasive, and by including the constituents in the optimum content to optimize the friction characteristics In this way, it is possible to minimize the amount of wear of the friction material and the counterpart material.

Preferably, the volume percent of the solid lubricant is 12 to 14, because when the volume fraction of the solid lubricant is less than 12 volume percent, a stable lubricating film is not formed and the change in the coefficient of friction increases at high temperature and high pressure, so that the fade resistance is increased. It decreases, causing the thermal deformation of the counterpart material and the formation of a uniform lubricating film due to the temperature of the counterpart material, causing the vibration to increase due to the vibration, and the aggressiveness of the friction material increases to increase the wear of the counterpart material. This is because the friction coefficient decreases when the volume fraction of the solid lubricant exceeds 14% by volume.

It is preferable that the volume% of the abrasive is 14 to 16, because when the volume fraction of the abrasive is less than 14% by volume, the role of the abrasive is insufficient and the friction coefficient is reduced, and the volume fraction of the abrasive is 16 vol. In case of exceeding%, the abrasion of the friction material increases and the amount of wear of the counterpart increases.If the temperature of the friction interface rises above the decomposition temperature of the solid lubricant, a stable lubrication film is not produced and the polishing effect by the abrasive increases. This is because a uniform lubricating film is formed by accelerating the temperature rise at the interface, causing a vibration phenomenon.

The solid lubricant according to the present invention is preferably graphite, antimony trisulfide (Sb ₂ S ₃ ) or a mixture thereof, but is not particularly limited as long as it is a conventional solid lubricant used in the art.

Non-steel friction material according to the invention is characterized in that it further comprises a fiber base, a binder, a filler and a friction control agent.

It is preferable that the volume percentage of the binder is 16-18, because when the volume fraction of the binder is less than 16% by volume, it is difficult to impart sufficient bonding force between the friction material components, so that the strength of the friction material decreases and exceeds 18 volume%. This is because the noise increases.

It is preferable that the volume% of the filler is 6 to 10, because the wear resistance increases when the volume fraction of the filler is less than 6 volume%, and the effect of the filler is insignificant when the volume fraction of the filler is more than 10 volume%. Because.

Preferably, the volume percentage of the friction modifier is 18 to 20, because the noise increases when the volume fraction of the friction modifier is less than 18 vol%, and when the volume modifier exceeds 20 vol%, the high temperature characteristics may deteriorate. Because.

In the present invention, the binder is preferably a commercial phenolic resin (straight phenolic resin) or strain-based phenol resin, but is not particularly limited as long as it is a binder commonly used in friction materials. In particular, in the present invention, as described above, by adjusting the relative amounts of the abrasive and the solid lubricant to form a stable lubricating film, it is possible to use not only the strain-based phenol resin but also a commercial phenol resin having low manufacturing cost.

The fiber base according to the present invention is preferably an organic fiber, a ceramic fiber, a bronze fiber or a mixture thereof, but is not particularly limited as long as it is commonly used for non-steel friction materials.

Examples of the organic fibers include carbon fibers, aramid fibers, aramid pulp, polyimide fibers, polyamide fibers, phenol fibers, cellulose or acrylic fibers, and the like, and ceramic fibers include rock wool and potassium titanate. (potassium titanate) and the like, and other inorganic fibers such as willlastonite, sepiolite, attapulgite and artificial mineral fibers may also be used.

The friction modifier according to the present invention is preferably cashew dust, tire rubber or a mixture thereof, but is not particularly limited as long as it is commonly used in friction materials.

The filler is preferably calcium hydroxide (CaOH), barite or mixtures thereof, but is not particularly limited as long as it is commonly used in friction materials.

The non-steel friction material according to the present invention is manufactured through a mixing, preforming, hot press molding, and a post curing process. In more detail, the method of preparation is followed by uniformly blending the friction agent composition in a suitable mixer such as a Henschel mixer, a Lodge mixer or an Aririch mixer, and then preforming the formulation in a mold. Next, the preform is hot pressed at a temperature of 130 to 200 ° C. and a pressure of 10 to 100 MPa for a time of 2 to 15 minutes, and then the hot press is heat treated at 140 to 250 ° C. for 2 to 48 hours. After the post-curing, the coating and baking, and if necessary, the surface polishing treatment to produce a non-steel friction material.

The vehicle disk of the present invention is characterized in that it comprises the non-steel friction material.

The non-steel friction material according to the present invention can be used in a wide range of applications including brake linings, clutch facings, disc pads, paper clutch facings and brake shoes in automobiles, heavy trucks, railway vehicles and various types of industrial machinery.

Hereinafter, the present invention will be described in more detail with reference to Examples and Test Examples. However, these Examples and Test Examples are intended to illustrate the present invention in more detail, it is apparent to those skilled in the art that the scope of the present invention is not limited by these Examples and Test Examples. .

Example

Example 1

Non-steel  Friction material

In the present invention, a non-steel friction material having a composition and composition ratio (volume fraction) as shown in Table 1 was used as Example 1.

Component  volume% importance Binder Commercial Phenolic Resin 17.70 1.3 Fiber base

Kevlar ^TM (Kevlar) 2.40 1.4 Potassium titanate 18.60 3.3 Bronze fiber 4.00 8.0 Organic friction modifier
Cashew Dust 17.10 1.2 Tire rubber 2.50 1.0 Abrasive
Zirconium Silicate (ZrSiO ₂ ) 2.00 4.43 Mica 7.00 2.85 Triiron tetraoxide (Fe ₃ O ₄ ) 6.50 5.0 Solid lubricant
Graphite 10.70 2.59 Antimony trisulfide (Sb ₂ S ₃ ) 3.00 4.6 filling
Calcium Hydroxide (CaOH) 1.00 2.2 Barite 7.50 4.3

In Example 1, as shown in Table 1, the fibrous substrate used Kevlar ^™ , a polyamide resin series, as the organic fiber, potassium titanate (Potassium Titanate) was used as the ceramic fiber, and bronze fiber was used. In addition, a commercial phenol resin was used as the binder.

In addition, a mixture of zirconium silicate (particle size 1 μm), mica, and triiron tetraoxide was used as an abrasive, and a mixture of graphite (particle size: 200 μm) and antimony trisulfide was used as a solid lubricant.

After the friction material component of Table 1 was prepared, the mixture was uniformly mixed in a lodge mixer of 1200 rpm or more, and preformed for 2 minutes by adding a surface pressure of 400 Kgf / cm ² at room temperature. The preform was hot pressed for 6 minutes by adding a surface pressure of 300 Kgf / cm ² at a temperature of 180 ° C., followed by postcure for 2 hours at 200 ° C. and 4 hours at 240 ° C. to prepare a non-steel friction material.

Comparative Example 1

Non-Steel Friction Material

In the present invention, a non-steel friction material having a composition and composition ratio (volume fraction) as shown in Table 2 was used as Comparative Example 1.

Component  volume% importance Binder Xyloke 17.70 1.3 Fiber base

Kevlar ^TM (Kevlar) 2.40 1.4 Potassium titanate 18.60 3.3 Bronze fiber 4.00 8.0 Organic friction modifier
Cashew Dust 17.10 1.2 Tire rubber 2.50 1.0 Abrasive
Zirconium Silicate (ZrSiO ₂ ) 3.00 4.43 Mica 8.00 2.85 Triiron tetraoxide (Fe ₃ O ₄ ) 6.50 5.0 Solid lubricant
Graphite 9.70 2.59 Antimony trisulfide (Sb ₂ S ₃ ) 2.00 4.6 filling
Calcium Hydroxide (CaOH) 1.00 2.2 Barite 7.50 4.3

The composition of Comparative Example 1 is the same as the composition of Example 1 (see Table 1), but the part using the modified phenol resin xylloc as a binder, as shown in Table 2, zirconium silicate (particle diameter of the abrasive component) 1 μm), the volume fraction is 3% by volume, the volume fraction of mica is 8.0% by volume, the volume fraction of graphite (particle size 200 μm) in the components of the solid lubricant is 9.70% by volume, and the volume of antimony trisulfide The difference is that the fraction is 2.0% by volume.

The manufacturing method of the friction material of the comparative example 1 is the same as the manufacturing method of Example 1, but only a difference is used in the component of Table 2.

Test Example

Test Example 1

Friction Performance Test

The friction performance test was performed using a 1/5 scale dynamometer, and the test was performed by mounting a gray cast iron disk and the friction material of Example 1 and Comparative Example 1. Friction performance (effect test and fade & recovery test) was devised by devising a modified test method of JASO 406C-P1, which is a proven test method to see the change of friction coefficient according to speed and braking deceleration and increase of friction coefficient with temperature increase. Tested.

Table 3 shows the procedure and conditions of the test.

Referring to Table 3, the test procedure is as follows. First, preburnishing was performed in order to make the newly produced friction material uniformly contact the counterpart (rotor) surface. 1 and 2 show the results of the above-described preversity test of Comparative Example 1 and Example 1. FIG. Next, perform a first effectiveness test to determine the change in friction coefficient for braking deceleration and then reburnishing to remove the effect on the first effect test. The first 1st Fade & Recovery test was then performed.

Thereafter, after the second reversing, the second 2nd Fade & Recovery test was performed, and after the third reversing, the second efficacy test was performed.

speed
(km / h) duration
(sec) IBT (℃) Braking deceleration (g) repeat
Count Reference Preburnish
(Preburnish) 65 - 120 0.3 200 Constant torque
(Constant Torque) 1st effect test
(1st Effectiveness)

50 - 80 0.1 to 0.6 6 or more at each speed

Constant pressure
(Constant Pressure)

100 0.1 to 0.8 130 0.1 to 0.8 1st Liberty
(Reburnish) 65 - 120 0.3 40 Constant torque
(Constant Torque) 1st Fade & Recovery base line
check
(Base line
check) 50 - 100 0.3 3 Constant torque
(Constant Torque) Fade
exam
(Fade
test) 100 - 100 at first brake application 0.45 10 Constant torque-constant time
(Constant Torque-Duration time)
Recovery
exam
(Recovery test) 50 50 - 0.35 12 2nd Liberty  Same as 1st Liberty 2nd Fade & Recovery  Same as 1st fade & recovery 3rd Liberty  Same as 1st Liberty 2nd effect test  Same as 1st effect test

The IBT denotes an initial brake temperature, the interval of repetition refers to the number of brakings during the test, and the duration time is determined until the speed is increased again after the braking is completed during the test. It means the time interval.

(1) effect test result

Figure 3 shows the first efficacy test results of Comparative Example 1.

Figure 4 shows the second efficacy test results of Comparative Example 1.

3 and 4, as the braking deceleration increases, the friction coefficient tends to decrease, and as the speed increases, the friction coefficient decreases. Comparative Example 1 can be seen that the friction coefficient is present in the range of about 0.30 to 0.62 as a whole in various situations.

Figure 5 shows the first efficacy test results of Example 1.

Figure 6 shows the second efficacy test results of Example 1.

5 and 6, in Example 1, unlike the Comparative Example 1, the friction coefficient does not tend to decrease as the braking deceleration increases, and the variation in the friction coefficient is smaller than that of Comparative Example 1 in the potency test. Able to know. The maximum width of the change in the friction coefficient of Example 1 was about 0.16 and the minimum was 0.05. Overall, the coefficient of friction is in the range of about 0.35 to 0.57, and the range is narrower than that of Comparative Example 1, indicating that the friction performance is stable.

(2) Fade & Recovery Test Results

Figure 7 shows the first fade & recovery test results of Comparative Example 1.

Figure 8 shows the second fade & recovery test results of Comparative Example 1.

Referring to FIGS. 7 and 8, in Comparative Example 1, the friction coefficient of about 0.2 was decreased in the fade test, and the friction coefficient was recovered in the recovery test.

9 shows the results of the first fade & recovery test of Example 1. FIG.

10 shows the second fade & recovery test results of Example 1. FIG.

9 and 10, in the case of Example 1, the maximum reduction of the friction coefficient in the fade test is 0.08, which is significantly less than that of Comparative Example 1, the recovery phenomenon can be seen that the similar tendency as in Comparative Example 1. .

In conclusion, as a result of the friction performance test, the friction material of Example 1 according to the present invention is less stable than the change of the friction coefficient according to the speed and the braking deceleration, and the resistance to fading is improved.

Test Example  2

Abrasion test

After the Example 1 and Comparative Example 1 were tested using the chassis dynamometer, the amount of wear was measured.

Figure 11 shows the results of measuring the amount of wear of Example 1 and Comparative Example 1.

Referring to FIG. 11, it can be seen that the amount of wear of Comparative Example 1 was higher than that of Example 1, where the abrasive content was higher and the solid lubricant content was lower. The results indicate that the amount of abrasion increases as the aggressiveness of the friction material increases, which means that as the relative amount of the solid lubricant decreases, the lubrication film is not sufficiently formed on the surface of the mating material, thereby increasing the temperature of the friction interface. It is considered that the resin being thermally decomposed and lost the bonding strength.

1 shows the results of the prevernish test of Comparative Example 1. FIG.

2 shows the results of the prevernish test of Example 1. FIG.

Figure 3 shows the first efficacy test results of Comparative Example 1.

Figure 4 shows the second efficacy test results of Comparative Example 1.

Figure 5 shows the first efficacy test results of Example 1.

Figure 6 shows the second efficacy test results of Example 1.

Figure 7 shows the first fade & recovery test results of Comparative Example 1.

Figure 8 shows the second fade & recovery test results of Comparative Example 1.

9 shows the results of the first fade & recovery test of Example 1. FIG.

10 shows the second fade & recovery test results of Example 1. FIG.

Figure 11 shows the results of measuring the amount of wear of Example 1 and Comparative Example 1.

Claims (12)

A non-steel friction material comprising 12 to 14 volume percent solid lubricant and 14 to 16 volume percent abrasive. The non-steel friction material according to claim 1, wherein the solid lubricant is graphite, antimony trisulfide or a mixture thereof. The non-steel friction material according to claim 1, wherein the abrasive is zircon silicate, mica, triiron tetraoxide or a mixture thereof. The non-steel friction material of claim 1, further comprising a fibrous substrate, a binder, a filler, and a friction modifier. 5. The non-steel friction material according to claim 4, wherein the volume% of the binder is 16-18. The non-steel friction material according to claim 4, wherein the volume% of the filler is 6 to 10. The non-steel friction material according to claim 4, wherein the volume percentage of the friction regulator is 18 to 20. The non-steel friction material according to claim 4, wherein the binder is a commercial phenol resin or a modified phenol resin. The non-steel friction material according to claim 4, wherein the fiber base material is organic fiber, ceramic fiber, bronze fiber or a mixture thereof. 5. The non-steel friction material according to claim 4, wherein the friction modifier is cashew dust, tire rubber or a mixture thereof. The non-steel friction material according to claim 4, wherein the filler is calcium hydroxide, barite or a mixture thereof. A vehicle brake comprising the non-steel friction material of any one of claims 1 to 11.

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