JPH11349924A - Production of carbonaceous friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a carbonaceous friction material having high durability and excellent frictional performances by firmly joining a carbonaceous friction material to a metal supporting plate. SOLUTION: A carbon fiber composite carbon sheet prepared by making a thermosetting resin adhere to a carbon fiber cloth, baking and carbonizing the resultant cloth is impregnated with a thermosetting resin, cured and molded. The resultant carbonaceous friction material is then thermocompression joined to a metal supporting plate with an adhesive comprising 20-40 wt.% of a nitrile rubber, 5-30 wt.% of a carbon black and 30-60 wt.% of a thermosetting resin. Since the carbonaceous friction material is firmly joined to the metal supporting plate, the carbonaceous friction material having high durability and excellent frictional performances can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a wet state in which an oil liquid such as lubricating oil is interposed between opposing friction surfaces.
For example, the present invention relates to a method for producing a carbonaceous friction material that can be suitably used for clutch facing, brake pads, differential limiting devices (LSD), and the like.

[0002]

2. Description of the Related Art As a carbonaceous friction material, a composite structure material in which a carbon fiber base material is bonded with a resin binder or a carbon binder has been developed. For example, Japanese Patent Application Laid-Open No. 50-72050 discloses a friction element for driving force in oil for transmitting force between movable parts, comprising one support material and one friction layer containing a carbon fiber web impregnated with an organic resin binder. However, JP-A-62-21528 discloses that a composition containing a fibrous substance such as carbon fiber and a binder is heated and pressed at 350
There has been proposed a method for producing a friction material which is heated in a non-oxidizing atmosphere at ~ 1000 ° C.

Japanese Patent Publication No. Sho 60-54270 discloses that a carbon material obtained by calcining a molded product obtained by solidifying a carbon fiber fabric with a furan resin or the like is treated with coal tar or coal tar and / or coal tar.
Or baking after impregnating pitch and furan resin,
Repeat impregnation and firing, and at least once at 2300
The coefficient of dynamic friction obtained by firing at a temperature of at least 0.1 ° C.
40, a carbon fiber reinforced carbon friction material having an abrasion amount of 100 × 10 ⁻⁴ mm / surface / stop or less is disclosed.
No. 222,353 discloses a fiber material containing carbon fiber, graphite fiber, etc., a thermosetting resin, a rubber compound and carbon black, wherein carbon black is compounded at a volume ratio of 2 to 15% with respect to the friction material. A friction material characterized by being made is disclosed.

[0004] The present applicant has also proposed a carbonaceous friction material,
Nitrogen adsorption specific surface area (N ₂ SA) of 70
m ² / g or more, DBP oil absorption is 90 ml / 100 g or more, carbon black having a characteristic of 2 to 20% by weight is added and kneaded, the kneaded material is applied to a carbon fiber base material, and hot-press cured, Next, after the cured sheet is cut into a predetermined shape, it is subjected to a calcination treatment at a temperature of 800 ° C. or more in a non-oxidizing atmosphere,
A method for producing a carbon-based wet friction material, comprising joining the obtained carbon-based composite material to a metal support plate (Japanese Patent Laid-Open No. 8-3268).
No. 06), impregnating a carbon fiber cloth with a thermosetting resin solution,
A thermosetting resin solution is again added to a carbon fiber composite carbon sheet (C / C sheet) having a porosity of 10 to 20% obtained by heating and curing and then calcining and carbonizing at a temperature of 800 ° C. or more in a non-oxidizing atmosphere. Of a carbon-based wet friction material, characterized in that a sheet base material having a porosity of less than 10% is produced by impregnation with heat, and the sheet base material is processed into a predetermined shape and joined to a metal support plate. Development of manufacturing method (Japanese Patent Application No. 9-139224)
is suggesting.

[0005]

However, all of the techniques disclosed in the above-mentioned patent publications relate to friction materials, and even a friction material having excellent friction performance is firmly joined to a metal support plate. If not, there is a problem that the function as a friction material cannot be sufficiently exhibited.

Accordingly, the present inventors have conducted intensive research on a method of firmly joining a carbonaceous friction material to a metal support plate, and as a result, the surface of a carbon fiber cloth braided with carbon fiber tows has a warp and a weft. Therefore, it is difficult to evenly disperse the adhesive over the entire surface of the cloth, and it is more difficult to evenly disperse the adhesive particularly when the shape is complicated. As a result, the joining strength between the friction material and the metal support plate is partially reduced, and sufficient friction performance cannot be exhibited. Therefore, it has been found that the bonding strength can be improved by bonding the surface of the carbon fiber cloth with the adhesive evenly interposed therebetween.

The present invention has been developed based on the above findings, and has as its object a method of manufacturing a carbonaceous friction material having excellent friction performance by firmly joining a carbonaceous friction material to a metal support plate. Is to provide.

[0008]

In order to achieve the above object, a method for producing a carbonaceous friction material according to the present invention comprises a carbon fiber composite carbon sheet obtained by applying a thermosetting resin to a carbon fiber cloth and calcining and carbonizing. A carbonaceous friction material obtained by impregnating a thermosetting resin with a thermosetting resin and curing and forming the same is mixed with 20 to 40% by weight of nitrile rubber, 5 to 30% by weight of carbon black, and 30 to 6% of thermosetting resin.
It is characterized in that it is hot-press bonded to a metal support plate using an adhesive consisting of 0% by weight.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a carbon fiber cloth constituting a carbonaceous friction material, a cloth such as a plain weave, a satin weave, a twill weave or the like manufactured from various materials such as polyacrylonitrile, rayon and pitch is used. Note that the carbon fiber cloth may be subjected to a surface treatment to improve wettability.

As the thermosetting resin to be adhered to the carbon fiber cloth, a highly carbonized thermosetting resin such as a phenol resin, a furan resin, an epoxy resin, an imide resin, and a melamine resin is used. These thermosetting resins are impregnated with a carbon fiber cloth in a liquid state and then semi-cured to form a prepreg, and then sandwiched between a heat-resistant metal plate and a ceramic plate at a temperature of 10 ° C./hr or less, preferably 5 ° C./hr or less. ° C / hr
It is heated to a temperature of 200 to 300 ° C. at the following temperature rising rate, and is held for an appropriate period of time to be cured, whereby it is adhered to the carbon fiber cloth.

The carbon fiber cloth coated with the thermosetting resin as described above is heated to a temperature of 800 ° C. or more in a heating furnace maintained in a non-oxidizing atmosphere such as nitrogen or argon, and subjected to a calcination carbonization treatment. Thereby, a carbon fiber composite carbon sheet is produced. Next, the carbon fiber composite carbon sheet is impregnated with a thermosetting resin, heated and cured to obtain a carbonaceous friction material.

According to the present invention, the carbonaceous friction material produced in this manner is bonded with a composition of 20 to 40% by weight of nitrile rubber, 5 to 30% by weight of carbon black, and 30 to 60% by weight of a thermosetting resin. It is characterized in that it is joined to a metal support plate by heat and pressure using an agent.

Since nitrile rubber has excellent flexibility,
The unevenness formed on the surface of the carbon fiber cloth by the warp and the weft can be evenly interposed. However,
Since nitrile rubber alone has low strength, carbon black is added to improve strength, and a thermosetting resin is added to increase the strength of the entire adhesive.

In this case, if the compounding amount of the nitrile rubber is less than 20% by weight, sufficient fluidity cannot be obtained at the time of joining due to low elasticity, while if it exceeds 40% by weight, the high-temperature strength decreases. If the amount of carbon black is less than 5% by weight, the effect of reinforcing the nitrile rubber is not sufficient, so that the strength of the adhesive is low. If it exceeds 30% by weight, the flexibility of the adhesive is impaired, and the thermosetting resin is further deteriorated. This also hinders the strength improvement. If the amount of the thermosetting resin is less than 30% by weight, the strength of the adhesive is not sufficient. If the amount is more than 60% by weight, the adhesive becomes too hard and causes a decrease in impact resistance. As the thermosetting resin, it is desirable to use the same type of resin as the thermosetting resin impregnated in the carbon fiber composite carbon sheet.

Using an adhesive having such a composition,
The carbon-based friction material can be firmly bonded to the metal support plate by hot-press bonding, and the adhesive layer is rich in flexibility and elasticity. However, it is possible to exhibit excellent durability.

The adhesive can be prepared, for example, by the following method. Carbon black is added to the nitrile rubber and kneaded, and a solution in which a thermosetting resin is dissolved in an organic solvent is added to the kneaded product and mixed well. In this case, the weight ratio of the organic solvent to the total solid content is preferably about 70:30. The mixed liquid material thus obtained is formed into a film-like thin piece with a doctor blade, and has a thickness of, for example, 15 μm.
A film-like adhesive sheet of about 0 to 200 μm is produced.

The adhesive sheet thus prepared is interposed between a carbonaceous friction material punched or cut into a predetermined shape such as a donut shape or a segment shape and a metal support plate such as an iron plate. The two are joined by heating and pressing to produce a carbonaceous friction material.
The conditions of the hot-press bonding are appropriately set according to the composition of the adhesive and the like, but are generally set at a temperature of 170 to 270 ° C. and a pressure of ^{2 to} 60 kg / cm ² . If the surface of the metal support plate is previously roughened by shot blasting or the like, the bonding strength can be further increased.

[0018]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Examples 1 to 6 and Comparative Examples 1 to 7 As the carbon fiber cloth, a plain woven cloth made by braiding 6 k (6000) of polyacrylonitrile-based carbon fibers was used. After a plain woven cloth was impregnated with a solution of the phenol resin precondensate dissolved in ethanol, the cloth was air-dried to volatilize and remove the ethanol and pre-cured. The prepreg sheet is heated to 250 ° C. at a temperature rising rate of 5 ° C./hr while applying a surface pressure of 10 kg / cm ² while being sandwiched between graphite-like flat plates, and is held for 2 hours to be heat-cured to obtain a plain weave cloth. Was coated with a thermosetting resin. Next, it was placed in an electric furnace maintained in a nitrogen gas atmosphere, and heated to 1000 ° C. at a rate of temperature increase of 25 ° C./hr, and calcined and carbonized.

In this way, a carbon fiber composite carbon sheet in which the plain woven cloth of carbon fiber and the carbide of phenol resin are integrated is prepared, and the sheet is impregnated with a solution obtained by dissolving a phenol resin precondensate in ethanol. It was air-dried to evaporate and remove ethanol, and was pre-cured. Then, the sheet was heated to 250 ° C. at a rate of 5 ° C./hr while applying a surface pressure of 10 kg / cm ² while being sandwiched between graphite flat plates,
After holding for 2 hours, the mixture was cured and molded to produce a carbonaceous friction material. The friction material was stamped and cut to produce a friction lining sheet having an outer diameter of 80 mm, an inner diameter of 50 mm, and a thickness of 0.5 mm.

Carbon black (commercially available H) is used as the nitrile rubber.
AF) were mixed at different ratios, and a solution in which a phenol resin was dissolved in methyl ethyl ketone was added to the kneaded mixture, followed by thorough mixing. This mixture was formed into a 150 μm thick film sheet by a doctor blade,
An adhesive sheet was prepared by cutting to an inner diameter of 50 mm and an inner diameter of 50 mm. The above carbonaceous friction material was adhered to a shot-blasted iron plate (outer diameter 80 mm, inner diameter 50 mm, thickness 1 mm) using adhesive sheets having different ratios of the nitrile rubber, carbon black, and phenolic resin prepared in this manner. Wear
Hold at a temperature of 200 ° C. and a pressure of 50 kg / cm ² for 5 minutes,
The carbonaceous friction material for the test was manufactured by hot-press bonding.

The shear strength of these carbonaceous friction materials was measured, and the joining strength was compared. Shear strength is JIS
According to K6833 (General Test Method for Adhesives), the shear rate was measured at 5 mm / min at room temperature and at 100 ° C. The obtained results are shown in Table 1 together with the composition of the adhesive.

[0023]

[Table 1]

From Table 1, the carbonaceous friction material of the example which was hot-pressure bonded using the adhesive of the composition specified in the present invention is the carbonaceous friction material of the comparative example which was hot-pressure bonded using an adhesive having a composition outside the range. The shear strength at room temperature and high temperature (100 ° C.) was higher than that of the material, indicating that the carbonaceous friction material was firmly joined to the metal support plate.

[0025]

As described above, according to the present invention, by using an adhesive having a composition of 20 to 40% by weight of nitrile rubber, 5 to 30% by weight of carbon black and 30 to 60% by weight of thermosetting resin, The carbonaceous friction material can be firmly hot-press bonded to the metal support plate. Further, it is possible to produce a carbonaceous friction material having high joining strength at a high temperature, high durability against sudden fluctuations in friction load and impact, and excellent friction performance.

Claims (1)

[Claims] 1. A carbon fiber friction material which is obtained by impregnating a thermosetting resin into a carbon fiber composite carbon sheet obtained by applying a thermosetting resin to a carbon fiber cloth and calcining and carbonizing the same, and curing and forming the carbonaceous friction material with a nitrile rubber in an amount of 20 to 40 wt. % Of carbon black, 5 to 30% by weight of a carbon black, and 30 to 60% by weight of a thermosetting resin.