JPH08337663A - Production of facing friction material - Google Patents

Abstract

PURPOSE: To provide a facing friction material excellent in abrasion resistance, friction characteristics, ν characteristics, and oil mobility. CONSTITUTION: A mixture of carbon fibers and aramid fibers is mixed with a friction modifier and a filler, formed into a sheet by a papermaking method, dried, impregnated with a polyamideimide resin soln., and thermally cured. Thus is formed a structure in which carbon fibers and aramid fibers are strongly and three-dimensionally entangled with each other and which has openings allowing a lubricant to move through. The friction modifier acts effectively to stabilize the coefficient of friction. The filler comes into spaces between fibers, providing good reinforcing effects. The polyamideimide resin fixes the materials strongly enough, effectively acting for increasing strengths and maintaining the openings. The amt. of the resin impregnated is easily controlled. The papermaking method gives a sheet with homogeneous dispersion and good and stable characteristics, and the impregnation with a polyamideimide resin, excellent in heat resistance, stabilizes the characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a facing friction material, and more particularly to a wear resistant material for machines, home appliances, etc.
The present invention relates to a method for producing a facing friction material useful as a friction member of an apparatus having a friction mechanism, such as a friction facing material for automobiles.

[0002]

2. Description of the Related Art Conventionally, this type of friction material is generally produced as a paper material which is formed into a sheet by paper-making, roll-forming or press-molding a composition containing a filler or fiber exhibiting friction performance, and is cut as appropriate. And is used as a friction material by adhering to a metal plate material serving as a core plate.

Therefore, the conventional product is mainly composed of a pulp material, in which friction materials are dispersed, and the whole is solidified with an organic binder.

[0004]

The friction material using the conventional paper-based facing friction material has the following drawbacks.

It is inferior in wear resistance and heat resistance, and does not exhibit the characteristics adapted to recent high performance specification specifications. Fillers are added and mixed in the interstices of the entangled sheet of pulp, but the state is uneven and it is difficult to obtain stable friction characteristics.

In order to secure the rapid movement of oil (lubricating oil), it is necessary to use a core plate having many oil grooves formed on the friction surface, but this processing is not easy and the processing cost is high. There is a problem of being expensive. Moreover, as the performance of automobiles has become higher in recent years, the pressure on the friction surface has also increased, and as a result, the oil grooves have worn down, making it impossible to achieve sufficient friction characteristics. In the facing friction material, due to the relationship between the sliding speed (V) and the friction coefficient (μ), the friction coefficient increases as the sliding speed increases (hereinafter, this characteristic is referred to as “μ-V characteristic”).
Called. ) Is a necessary condition. The conventional paper-based facing friction material has a proportional relationship between the sliding speed and the friction coefficient, but it has poor wear resistance and is difficult to put into practical use under severe usage conditions. Moreover, no one of the μ-V characteristics can maintain a good value under a high surface pressure condition for a long period of time. For this reason, the conventional paper-based facing friction material cannot satisfy the μ-V characteristic and wear resistance corresponding to the friction mechanism of automobiles and the like which have been improved in performance recently. Therefore, there is a demand for a facing friction material having characteristics that are compatible with high performance of automobiles and the like.

The present invention solves the above-mentioned conventional problems and is excellent in wear resistance and frictional characteristics, particularly in μ-V characteristics, and
It is an object of the present invention to provide a method of manufacturing a facing friction material that does not require oil groove processing on a core plate because it has excellent oil mobility.

[0008]

According to a first aspect of the present invention, there is provided a facing friction material manufacturing method, wherein a friction modifier and a filler are added to and mixed with a mixture of carbon fiber and aramid fiber, and then papermaking is performed. After drying the sheet, the sheet is characterized in that the sheet is impregnated with the polyamideimide resin liquid, and then heat-treated.

A method for manufacturing a facing friction material according to a second aspect is the method according to the first aspect, wherein the friction modifier is polytetrafluoroethylene powder, MoS ₂ powder, carbon powder and alumina powder, and the filler is CaCO ₃ , One or two or more selected from the group consisting of SiO ₂ and diatomaceous earth.

The method for producing a facing friction material according to claim 3 is the method according to claim 1 or 2, wherein the mixing ratio of carbon fiber and aramid fiber is 50 to 85% by weight of carbon fiber and 50 to 15 of aramid fiber. % By weight, and the mixing ratio of each powder of the friction modifier is 1 to 1 with respect to the mixture of carbon fiber and aramid fiber.
10% by weight, the mixing ratio of the filler is 5 to 50% by weight with respect to the mixture of carbon fiber and aramid fiber, and the impregnation amount of the polyamide-imide resin is carbon fiber, aramid fiber, friction modifier, It is characterized by being 10 to 20% by weight based on the total amount of the filler and the polyamide-imide resin.

The present invention will be described in detail below.

In the present invention, first, carbon fibers and aramid fibers are uniformly mixed. When this carbon fiber is mixed, if the proportion of carbon fiber is high, the abrasion resistance of the facing friction material obtained will be high, and if the amount of aramid fiber is high, the entanglement strength of the fiber will tend to increase.
Therefore, in the present invention, the mixing ratio of these fibrous materials is 50 to 85% by weight of carbon fibers, 50 to 15% by weight of aramid fibers, and particularly 40 to 15% of aramid fibers to 60 to 85% by weight of carbon fibers. It is preferably set to wt%.

The carbon fiber used preferably has a fiber diameter of 6 to 10 μm and a fiber length of 20 to 100 μm, and the aramid fiber has a fiber diameter of 5 to 100 μm.
m, and the fiber length is preferably several mm to 30 mm.

As the friction modifier added to and mixed with these mixed fiber materials, polytetrafluoroethylene (PTFE) powder, MoS ₂ (molybdenum disulfide powder), carbon powder and alumina (Al ₂ O ₃ ) powder are added together. It is preferable that the addition amount is 1 to 10% by weight based on the total of carbon fiber and aramid fiber, and the total amount is 5%.
It is preferably 10 to 10% by weight. The alumina powder content is particularly preferably 1 to 3% by weight. These friction modifiers are not necessarily limited to the case of using four kinds in combination, and one kind may be added alone or any two kinds or three kinds out of four kinds may be added. The particle size of each powder of the friction modifier is preferably 3 to 50 μm.

If the proportion of the friction modifier is less than the above range, the compounding effect cannot be sufficiently obtained, and if it exceeds the above range, problems such as difficulty in uniform dispersion and mixing occur.

As the filler, one or more selected from the group consisting of CaCO ₃ (calcium carbonate), SiO ₂ (silica) and diatomaceous earth can be used, and the addition amount thereof is carbon fiber and aramid fiber. Is preferably 5 to 50% by weight with respect to the total of If the proportion of the filler is less than 5% by weight, the compounding effect cannot be sufficiently obtained,
If it exceeds 50% by weight, problems such as difficulty in uniformly dispersing and mixing occur.

In the present invention, the polyamide-imide resin used as the binder is carbon fiber,
It is preferably 10 to 20% by weight based on the total weight of the aramid fiber, the friction modifier, the filler and the polyamide-imide resin. If the proportion of the polyamide-imide resin is less than 10% by weight, sufficient binding strength due to the binder resin cannot be obtained, and 2
If it exceeds 0% by weight, the resin content is too large and the frictional properties are deteriorated, and it becomes impossible to form a porous material effective in eliminating the lubricating oil.

In the present invention, the carbon fiber is uniformly dispersed in the aramid fiber, and the papermaking method is adopted to sufficiently mix the friction modifier and the filler in the mixed fiber material. The obtained paper sheet is impregnated with the polyamide-imide resin liquid.

That is, first, appropriate amounts of carbon fiber and aramid fiber are wet-mixed and mixed, and these fibers are
Disperse well and evenly. Water is usually used as the wet mixed solvent, and the amount of water used is preferably water: fiber material = 50 to 150: 1, and more preferably about 100: 1.

If the amount of the fibrous material is less than this, it does not affect the papermaking, but it is not preferable since it takes a lot of water because it treats a lot of water. Further, if the amount of the fibrous material is remarkably larger than this ratio, it is inconvenient because the fibrous material is not crushed and mixed sufficiently uniformly in water.

After that, the friction adjusting material and the filler are added and mixed into the water containing the dispersed fiber material, and the mixture is further stirred and mixed. In addition,
Upon this mixing, a thickener such as a sulfuric acid band is added, if necessary, in order to stabilize each material and to secure the viscosity required for papermaking.

The obtained paper-making raw material is made into a paper-making sheet by a conventional method, and the paper-making sheet is dried.

Then, the dried sheet is dipped in a solution of polyamideimide resin dissolved in a suitable solvent to impregnate the sheet with the polyamideimide resin solution.
In this impregnation treatment, the amount of polyamideimide resin impregnated can be freely adjusted by adjusting the concentration of polyamideimide resin in the polyamideimide resin liquid, and the sheet is impregnated with polyamideimide resin extremely uniformly. be able to.

After the impregnation treatment, the sheet is heat-cured. The condition is about 60 at a temperature of 250 to 300 ° C.
It is necessary to hold for about a minute, and the pressure is several kgf / c
It is suitable to set it to about m ^{2 to} 50 kgf / cm ² .
By this thermosetting treatment, the fiber material and various powders can be fixed.

In the present invention, a paper sheet having a thickness of 100 to 500 μm is obtained by the above method, dried, impregnated with a polyamideimide resin solution, and heat-treated to give a thermosetting sheet having a thickness of 70 to 300 μm. Is preferred.

The thermosetting sheet thus obtained is
It can be used as a facing material by adhering it to an appropriate core plate, but in that case, since the thermosetting sheet has good porosity and excellent lubricating oil exclusion properties, it is possible to eliminate the need for groove processing of the core plate. it can. Of course, if necessary, the core plate may be grooved before use.

In the present invention, the metal material constituting the core plate is not particularly limited, and the present invention can be applied to any core plate made of metal material, but preferably, it is inexpensive generally used conventionally. Examples include iron alloys and lightweight aluminum alloys.

[0028]

The present inventor has conducted various studies on additive materials and manufacturing methods in order to develop a μ-V characteristic in a paper-based facing friction material, that is, a characteristic that the friction coefficient maintains an increasing tendency as the sliding speed increases. As a result of stacking, the surface condition of the friction material layer of the facing friction material has a great influence on the μ-V characteristics, and the surface condition of the friction material layer has a certain degree of unevenness. It has been found that being porous from the surface to the inside is an important requirement for improving the μ-V characteristic.

That is, in order to obtain the friction characteristics desired as a facing friction material, the lubricating oil content can be promptly removed from the friction material layer surface, the friction material layer itself is slightly elastically deformed, and the surface is resistant to abrasion. A high tensile strength is an essential condition. Of these, conventional removal of lubricating oil includes conventional grooving and porosity imparting according to the present invention.

In the present invention, by making the friction material layer porous, the lubricating oil content of the friction surface is rapidly moved to the inside of the friction material layer at the time of a high sliding speed, whereby the friction coefficient of the friction surface is increased. Good μ-V characteristics are ensured without decreasing

Further, in the present invention, in order to further improve the performance such as the μ-V characteristic, the friction material layer is made porous, and the high-strength fibers are blended in a sufficiently large amount and uniformly.

In the present invention, carbon fibers and aramid fibers are used in combination as a means for blending a large amount of these high strength fibers. By using carbon fiber and aramid fiber in combination in this way, it becomes possible to mix long fibers, which was impossible in the past, as well as the mixing ratio of carbon fiber and aramid fiber and the thickness of the friction material layer. Also, it became possible to control arbitrarily.

The effects of the combined use of carbon fiber and aramid fiber in the present invention are as follows.

That is, although carbon fiber is a short fiber and has high rigidity, it is impossible to mix a large amount with carbon fiber alone, but by using aramid fiber in combination with this, the degree of freedom of mixing can be increased, and a large amount of carbon fiber can be mixed. It will be possible.

This is because when carbon fibers and aramid fibers are used in combination, different kinds of fibers are entangled three-dimensionally. In the present invention, the carbon fibers and aramid fibers are entangled as described above, And,
It is firmly fixed by the polyamide-imide resin that is a binder to form a high-strength friction material layer. In addition, a fine gap is formed in the friction material layer by this three-dimensional entanglement, oil can be moved, and the friction adjusting material and the filler enter into the gap to reinforce the friction characteristic, Other performance is improved.

In the present invention, a combination of carbon fibers and aramid fibers is used to form a strong three-dimensional fiber entangled structure by blending a large amount of fibers and to form a gap through which lubricating oil can move. To do. The friction modifier effectively functions to stabilize the friction coefficient. The filler penetrates into the gap between the fibrous materials and exhibits a good reinforcing effect. The polyamide-imide resin firmly and three-dimensionally fixes the fibrous material, the friction modifier and the filler, and effectively acts to increase the strength and maintain voids. Moreover, since the polyamide-imide resin is impregnated in a liquid state, the impregnated amount can be freely adjusted, and by adjusting the impregnated amount, different facing friction materials can be manufactured according to the purpose.
In addition, the polyamide-imide resin is also excellent in heat resistance and wear resistance, and is therefore advantageous in improving the characteristics of the facing friction material. Since each material is made into a paper, a good paper sheet can be obtained in a uniformly dispersed state, and a polyamide-imide resin can be impregnated into this to obtain stable characteristics. With such effects, it is possible to obtain a facing friction material having good friction characteristics and high wear resistance, and particularly excellent in μ-V characteristics.

[0037]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Examples 1 to 3 Carbon fibers (average fiber diameter 10 μm, average fiber length 70 μm) and aramid fibers (average fiber diameter 10 μm, average fiber length 15 mm) were mixed in the proportions shown in Table 1,
A uniform mixture was obtained by forced stirring in water. In addition,
In this stirring and mixing, water was used in an amount of 10 liters per 100 g of the fibers, and stirring was performed for 60 minutes. next,
P is used as a friction modifier for 100 g of fibers in total.
TFE powder (average particle size 10 μm), MoS ₂ (average particle size 10 μm), carbon powder (average particle size 40 μm), alumina powder (average particle size 5 μm) and CaC as filler
O ₃ powder (average particle size 8 μm) was added and mixed in the proportions shown in Table 1, and further stirred and mixed for 10 minutes. At this time, a small amount of a sulfuric acid band was added while observing the state of mixing to increase the viscosity.

The mixed liquid was dehydrated by a papermaking machine to obtain a sheet having a thickness of about 1 mm. The sheet is dried and the polyamide-imide resin is added to the N-methylpyrrolidone solvent at 30% by weight.
A polyamide-imide resin solution dissolved at a concentration was impregnated to the impregnation amount shown in Table 1 at 250 ° C. and 10 kgf.
The sheet was heated and pressed at a pressure of / cm ² for 60 minutes, and this hot-pressed sheet (thickness: 0.2 mm) was adhered to a flat iron plate (disc) not grooved to form a facing material.

Using the obtained facing material, abrasion resistance (using a disc material of S45C steel as a mating material for 500 minutes or 10 minutes
The amount of wear (μm) in a sliding test at a speed of 00 minutes and 50 RPM) and the μ-V characteristics (relationship between the sliding speed and the friction coefficient measured by a SAE type tester) were examined, and the results are shown in Table 1. It was

Comparative Example 1 With respect to a conventional paper-based facing friction material (paper-based friction material thickness 500 μm), abrasion resistance and μ-V characteristics were examined in the same manner as above, and the results are shown in Table 1.

[0042]

[Table 1]

From Table 1, it is clear that the facing friction material of the present invention has excellent wear resistance and good μ-V characteristics.

[0044]

As described in detail above, according to the method for manufacturing a facing friction material of the present invention, the abrasion resistance is remarkably excellent. The μ-V characteristic is excellent. Excellent heat resistance and durability. The friction coefficient does not change over time and is stable over a long period of time. The oil groove processing on the core plate can be eliminated, and the labor and processing cost of processing can be reduced. Further, there is no problem of deterioration of frictional characteristics due to wear of the groove. It is possible to reliably manufacture the facing friction material having the target characteristics without variations in performance. A facing friction material having excellent characteristics such as the above is provided.

Claims (3)

[Claims] 1. A mixture of carbon fiber and aramid fiber, a friction modifier and a filler are added and mixed, and then papermaking is performed. The obtained papermaking sheet is dried, and then the polyamideimide resin liquid is impregnated into the sheet, Then, a method of manufacturing a facing friction material, which is characterized by heat curing treatment. 2. The method according to claim 1, wherein the friction modifier is polytetrafluoroethylene powder, MoS ₂ powder, carbon powder and alumina powder, and the filler is CaCO ₃ ,
1 or 2 selected from the group consisting of SiO ₂ and diatomaceous earth
A method for producing a facing friction material, characterized in that it is of at least one kind. 3. The method according to claim 1 or 2, wherein the mixing ratio of the carbon fiber and the aramid fiber is 50 to 85% by weight of the carbon fiber and 50 to 15% by weight of the aramid fiber. The mixing ratio of the powder is 1 to 10% by weight with respect to the mixture of carbon fiber and aramid fiber.
The mixing ratio of the filler is 5 to 50% by weight with respect to the mixture of carbon fiber and aramid fiber, and the impregnated amount of the polyamide-imide resin is carbon fiber, aramid fiber, friction modifier, filler and A method for producing a facing friction material, characterized in that the content of the polyamide-imide resin is 10 to 20% by weight.