JPS6351432A - Friction material and production thereof - Google Patents

Abstract

PURPOSE:To obtain a friction material having excellent friction properties, strength, heat resistance, flame retardance, etc., by impregnating a matrix resin into a pitch based carbon fiber having a specific fiber diameter and molding the impregnated fiber, and if necessary, carbonizing the resultant moldings. CONSTITUTION:Pitch based carbon fiber having >=10mum fiber diameter is impregnated with a matrix resin (preferably polystyrylpyridine based resin or said resin-containing resins) and the impregnated fiber is molded normally by hot curing to provide a friction material consisting of carbon fiber-reinforced composite material. Further, the above-mentioned composite material is carbonized to afford a friction material consisting of carbon fiber-reinforced carbon composite material. The process consisting of above-mentioned impregnation of resin and carbonization is carried out at <=3 times. The above-mentioned polystyrylpyridine based resin is, e.g. obtained by polycondensing terephthal aldehyde with 2,6-lutidine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides carbon f11.
The present invention relates to a friction material using a fiber-reinforced composite material or a carbon fiber-reinforced carbon composite material obtained by carbonizing the composite material, and a method for producing the same.

(Prior Art and its Problems) Generally, friction materials reinforced with carbon fibers having a thread diameter of less than 10 μm are used in brake materials for aircraft, racing cars, and the like.

However, as transportation equipment continues to become faster and lighter, there is a desire to develop friction materials with higher performance that meet these demands.

(Means for Solving the Problems) As a result of intensive research into friction materials made of carbon fiber-reinforced molding materials particularly excellent in friction properties, strength, etc., the present inventors found that pitch-based carbon fibers with a thread diameter of 10 μm or more The present invention has been achieved by using a composite material having as a reinforcing material.

That is, the present invention is characterized by comprising a carbon fiber-reinforced composite material containing pitch-based carbon fibers with a thread diameter of 10 trm or more and a matrix resin, or a carbon fiber-reinforced carbon composite material obtained by carbonizing the composite material. Friction material and thread diameter 10μm
The present invention relates to the manufacturability of a friction material characterized in that the above pitch-based carbon D4 is impregnated with IJ sock fat, then carbonized, and the process of impregnating and carbonizing the resin is performed three times or less.

The thread diameter used in the present invention is 10 μm or more, preferably 12 μm or more.
The pitch-based carbon fiber reinforcement of ~18 μm generally uses petroleum or coal pitch, and continuous fibers or short fibers that can be easily produced by melt spinning, melt centrifugal spinning, eddy current method, etc. can be used. These continuous fibers and short fibers can be used by further processing them into chopped fibers, milled fibers, knitted fabrics, felts, mats, nonwoven fabrics, etc.

Naturally, industrially produced continuous fibers of pitch-based carbon fibers and processed products thereof can also be used in the present invention, but
Since these continuous fibers are extremely expensive, it is advantageous to use inexpensive short fibers when used in general-purpose friction materials.

Prior to the present invention, the present inventors combined a thermoplastic resin with carbon fibers of various thread diameters and measured their friction resistance and wear characteristics. As a result, it has been found that relatively thick yarns with a diameter of 10 μm or more have better friction resistance and wear characteristics than thinner yarns.

The matrix resin used in the present invention includes:

Polystyrylpyridine resin (hereinafter referred to as PSP resin), February? Examples include oxy resin, phenol resin, polyimide resin, vinyl ester resin, furan resin, pitch, etc., but PSP resin alone or containing PSP resin is particularly preferable.

The above-mentioned PSP resins are combined with aromatic dialdehydes such as terephmeraldehyde and 2,6-
Lutidine, 2,4,6-collidine, and at least 2
It is obtained by polycondensation with a pyridine derivative substituted with reactive methyl groups.

Such resins usually have the general formula % (1) where RI R1 represents a segment consisting of the same or different hydrocarbon groups and may contain heteroatoms, A and A1 are the same or different ether groups,
Indicates a steric transfer bonding group such as a sulfone group, R, R1
and the aromatic ring of the styrylpyridine chain, R2 represents hydrogen, a methyl group, or an ethyl group, and k l tlm represents an integer that may be equal to zero. ].

PSP resin has excellent heat resistance, flame resistance, and low smoke generation.
It also has a higher carbonization rate than phenol resins, polyimide resins, etc. Table 1 shows the results of comparing the carbonization rate for each resin.

Table 1 (Note) The temperatures in the table are carbonization temperatures.

Furthermore, the carbonization rate of PSP resin at 1000°C in an inert atmosphere is still 65 mm, which is more advantageous than using pitch or phenol resin.As a result, it is possible to reduce the impregnation, densification, and carbonization steps. .

The PSP resin used in the present invention may be used in combination with a resin having a relatively high carbonization rate, such as a phenol resin or a polyimide resin, as long as the purpose of the present invention is not impaired. The combined use of these resins has a great advantage in terms of reducing the bottom shape time and curing temperature of the PSP resin. Molding conditions for PSP resin alone vary depending on the base material used, molding method, resin grade, etc., but generally require 3 hours or more at 200°C. In the present invention, resins that have a relatively high carbonization rate and are effective in improving the bottom shape conditions of PsP resins include resol type or novolak type phenolic resin, noblack phenol type epoxy resin, BOOTS-TECHNOCH
Examples include bismaleimide resins such as EMI E's iM'''CO IMIDE'', or combinations of bismaleimide and allylphenol compounds such as σ, θ'-diallyl bisphenol A. .

The amount of these resins that can be used in combination with the PSP resin is normal.

1 to 70 parts by weight for PSP resin, preferably 5 to 5 parts
0 weight related weight equivalent.

The carbon fiber reinforced composite material that is not carbonized in the present invention (hereinafter referred to as non-carbonized composite material) is made by containing a pitch-based carbon fiber base material with a thread diameter of 10 μm or more in an amount of usually 10 to 70% by weight. It is. The tabulation of such a composite material varies depending on the shape of the base material used, but it is possible to use a resin impregnation method or a modified method in which the resin is uniformly adhered to the base material without using an appropriate solvent. The non-carbonized composite material can be used depending on the shape of the final friction material, the required R, the required number, etc., and can be molded by various methods such as injection bottom molding, hot press molding, autoclave molding, and transfer molding. By selecting the shape of the pitch-based carbon Rm and the type of matrix resin to suit these various bottom shape conditions, it is possible to create, for example, pellet dog injection molding materials, short fibers whose fiber surfaces are coated with a resin component and made into a semi-hardened state. It can be used as a non-carbonized composite material (molding material) such as injection molding and hot paste type material, sheet molding compound, bulk molding compound, flitereg, etc.

Incidentally, the pitch-based carbon fiber base material used in the present invention contains inorganic fillers, such as glass fiber, gold (4 fibers, ceramic fibers, asbestos, silicon carbide, silicon nitride, kaolin, zeolite, mica, Merck, Titanium oxide, molybdenum disulfide, graphite, gypsum, quartz, etc., depending on the purpose.
20% by weight can be added.

Further, in the present invention, when impregnating the fiber base material with a resin,
Various solvents can be added to the resin as necessary for the purpose of reducing the viscosity of the resin and facilitating impregnation.

The non-carbonized composite material in the present invention is usually heated at a temperature of 100 to 300°C.
It is preferably cured and molded at 150 to 270°C. After such curing treatment, it is preferable to further perform post-curing at 200 to 270° C. for one hour or more.

The carbon fiber-reinforced carbon composite material (C/C Composoft) obtained by carbonizing the non-carbonized composite material of the present invention is used for the above molding material,
The carbonization treatment conditions can be selected depending on the purpose, shape of the base material, carbonization rate of the matrix resin, etc.

If the friction material of the present invention is used in a temperature range of about 300°C or lower, it will bite even if it is made of a non-carbonized composite material that has not been carbonized after forming.

Also, when using at temperatures exceeding 300℃,
A friction material made of a C/C composite obtained by carbonizing IJ Fuchs fat at approximately 1000° C. or lower in a reducing atmosphere is used. Furthermore, when used in a temperature range exceeding 500°C and up to about 1000°C, it is necessary to set the oxidation resistance temperature to preferably 800°C or higher, so 1000°C to 3000°C.
Carbonization treatment is required. When performing carbonization treatment at such high temperatures, it is also possible to further improve oxidation resistance by treating with phosphorus, boron compounds, etc., as is already known. Also, c/c obtained in this way:
1. Friction materials from the base usually have a carbon fiber base material containing M.
The weight range is 10-85% by weight, preferably 20-80% by weight.

(Effects of the Invention) The composition of the present invention has excellent heat resistance, flame retardancy, mechanical strength when heated, and 1III friction and wear properties, and is used as a brake for sliding parts of machines, aircraft, racing cars, etc. It is useful for friction materials such as materials.

(Example) Next, the present invention will be further explained with reference to Examples and Reference Examples. In addition, parts and units in the examples are based on weight.

Reference Example 1 Polyamide 6.6 and polyphenylene sulfide (pps) were used as matrix resins, and more than 30 carbon fibers with different thread diameters were mixed therein, and their wear characteristics were compared. The results are shown in Table 2.

Example 1 Pitch-based carbon fiber short fiber mat with a thread diameter of 12 to 15 μm (Ousuki Ink Chemical Industry ■Prototype, thread length: 10 to 20
σ) Made with felt by needle punch. Please note that the bulk specific gravity of felt is approximately 0.045g/(7)3. P.S.
P 6022M (PSP resin, manufactured by 5NPE, solid content 75 ml methyl ethyl ketone solution) was used as a matrix resin, and this was used as methyl ethyl ketone (~fEK) K
It was diluted more thoroughly and impregnated into felt by the dipping method.

Further, it was dried for 6 minutes at 110° C. in a hot air dryer. Thereafter, 8 sheets (apparent thickness: approx. 15 cm) were stacked, placed on a press plate, held at 200°C for 30 minutes, and then heated to 220°C.
Heat and pressurize at approximately 20 mm/m' for 10 minutes at
The temperature was raised to 50°C, and pressure molding was performed at 110 kg/crn2 for 1 hour. The thickness of the resulting preformed product is approximately 8.0 + m,
The density was 1.45 g/crnI. The friction characteristics of this product were as shown in Table 3.

Table 3 This product did not require any heat treatment at high temperatures when used at temperatures below 300°C.

Furthermore, this molded product was heat-treated in air at 400° C. for 2 hours. The felt itself used as a reinforcing material was exposed to air for 40 minutes.
If left at 0°C for 2 hours, most of the molded product would deteriorate, but the molded product did not change in appearance. In this case, the M amount decrease was approximately 4.7 times.

Example 2 The molded product obtained in Example 1 was heat treated at up to 1000° C. in a nitrogen atmosphere embedded in coke. Furthermore, the material was heat-treated up to 2000°C.

Their friction characteristics are shown in Table 4.

Small piece of molded product (3 x 3 m) fired to 2000℃
We measured the weight loss in air using TGA.

As a result, there was a weight decrease of 10 cm at about 850°C. Example 3 Pitch-based carbon fiber short fiber mat with a thread diameter of 12 to 15 μm (Dainippon Ink and Chemicals (7) Prototype, thread length; 10
~20m) was made into milled fibers with a yarn length of 21 or less using a mixer.

PSP6022PC (manufactured by 5NPE) and COMPIMI
DE 795 (Boors-TEcHNocI (EMr
(manufactured by Company G) were mixed at a ratio of 70:30 and used as a matrix resin.

There is naturally no problem in using PSP 6022 PC alone as a 1-trix resin, but C (Mvi
By mixing PIMIDE, the molding time could be shortened.

Mix 30 parts of the milled fiber and 70 parts of the matrix resin uniformly, fill it into a mold at 150°C,
Next, raise the temperature to 180℃ and hold for 2-3 minutes, then raise the temperature to 200℃
20 kg/mouth for 25 minutes, followed by 22
Raise the temperature to 0℃, pressurize at 50℃ for 25 minutes, and then pressurize for 25 minutes.
Raise the temperature to 50℃ and increase the temperature to 100-200 kg/cm2.
The molded product is formed by applying pressure for 0 minutes. The obtained molded product was post-cured at 250°C for 3 to 5 hours. Table 5 shows the physical properties of the molded product.

Table 5 Example 4 Using the same felt as Example 1, PSP6022M and COMPIMIDE 795 gold 6 as matrix resin
The mixture was diluted with MEK at a weight ratio of 0:40 and was impregnated by the dipping method.

A molded product was obtained by almost the same operation as in Example 1.

However, in this case, the molding time was 1 hour. The molded product was heated to 200°C/hour in a nitrogen atmosphere to 100°C.
The cymatrix resin was carbonized by keeping at 00° C. for 30 minutes and cooling. This is an even higher concentration of PSP
6022 P C/COMPIMIDE 795 ME
Carbonization was performed by immersing it in a K solution. The density of the obtained C/C composite was 1.4697cm''.This material was further heat-treated at up to 2000°C in a nitrogen atmosphere to reduce the density to 3%.
A molded product with excellent oxidation resistance was obtained by immersing it in an IJ acid aqueous solution and drying it. The physical properties are shown in Table 6 [7].

Table 6 The oxidation resistance temperature measured by TGA was 1 at approximately 870℃.
There was a weight loss of 0.

Claims (1)

[Claims] 1. A friction material comprising a carbon fiber-reinforced composite material containing pitch-based carbon fibers with a thread diameter of 10 μm or more and a matrix resin, or a carbon fiber-reinforced carbon composite material obtained by carbonizing the composite material. . 2. The friction material according to claim 1, wherein the matrix resin is a polystyrylpyridine resin. 3. A method for producing a friction material, which comprises impregnating pitch-based carbon fibers with a thread diameter of 10 μm or more with a matrix resin, then carbonizing the fibers, and performing the steps of impregnating and carbonizing the resin three times or less.