CA2090559A1 - Friction material composition and process for production thereof - Google Patents
Friction material composition and process for production thereofInfo
- Publication number
- CA2090559A1 CA2090559A1 CA002090559A CA2090559A CA2090559A1 CA 2090559 A1 CA2090559 A1 CA 2090559A1 CA 002090559 A CA002090559 A CA 002090559A CA 2090559 A CA2090559 A CA 2090559A CA 2090559 A1 CA2090559 A1 CA 2090559A1
- Authority
- CA
- Canada
- Prior art keywords
- fiber
- friction material
- material composition
- resin
- polyacrylonitrile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 50
- 239000002783 friction material Substances 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 11
- 239000004917 carbon fiber Substances 0.000 claims abstract description 42
- 239000000835 fiber Substances 0.000 claims abstract description 42
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229920000049 Carbon (fiber) Polymers 0.000 claims abstract description 39
- 229920002239 polyacrylonitrile Polymers 0.000 claims abstract description 32
- 229920005989 resin Polymers 0.000 claims abstract description 24
- 239000011347 resin Substances 0.000 claims abstract description 24
- 239000000463 material Substances 0.000 claims abstract description 20
- 229920001187 thermosetting polymer Polymers 0.000 claims abstract description 17
- 238000001914 filtration Methods 0.000 claims abstract description 7
- 239000006185 dispersion Substances 0.000 claims abstract description 6
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 238000000465 moulding Methods 0.000 claims abstract description 4
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 9
- 229920001721 polyimide Polymers 0.000 claims description 7
- 239000004760 aramid Substances 0.000 claims description 6
- 239000009719 polyimide resin Substances 0.000 claims description 6
- 229920003235 aromatic polyamide Polymers 0.000 claims description 5
- 229920001568 phenolic resin Polymers 0.000 claims description 5
- 239000005011 phenolic resin Substances 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229920006282 Phenolic fiber Polymers 0.000 claims description 3
- 229920001807 Urea-formaldehyde Polymers 0.000 claims description 3
- 239000003822 epoxy resin Substances 0.000 claims description 3
- 239000011490 mineral wool Substances 0.000 claims description 3
- 229920000647 polyepoxide Polymers 0.000 claims description 3
- 229920005749 polyurethane resin Polymers 0.000 claims description 3
- 244000226021 Anacardium occidentale Species 0.000 claims description 2
- 239000006229 carbon black Substances 0.000 claims description 2
- 235000020226 cashew nut Nutrition 0.000 claims description 2
- 239000000428 dust Substances 0.000 claims description 2
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine powder Natural products NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 claims 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims 1
- 229910002804 graphite Inorganic materials 0.000 claims 1
- 239000010439 graphite Substances 0.000 claims 1
- 229910052750 molybdenum Inorganic materials 0.000 claims 1
- 239000011733 molybdenum Substances 0.000 claims 1
- 230000009467 reduction Effects 0.000 abstract description 7
- 238000005299 abrasion Methods 0.000 abstract description 6
- 239000000306 component Substances 0.000 description 10
- 150000002500 ions Chemical class 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 101100270435 Mus musculus Arhgef12 gene Proteins 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- KVFIJIWMDBAGDP-UHFFFAOYSA-N ethylpyrazine Chemical compound CCC1=CN=CC=N1 KVFIJIWMDBAGDP-UHFFFAOYSA-N 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
- F16D69/02—Composition of linings ; Methods of manufacturing
- F16D69/025—Compositions based on an organic binder
- F16D69/026—Compositions based on an organic binder containing fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/006—Pressing and sintering powders, granules or fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/16—Frictional elements, e.g. brake or clutch linings
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/0005—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing non-specific motion; Details common to machines covered by H02N2/02 - H02N2/16
- H02N2/005—Mechanical details, e.g. housings
- H02N2/0065—Friction interface
- H02N2/007—Materials
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Braking Arrangements (AREA)
- General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Abstract The present invention provides a friction material composition which, when used in an ultrasonic motor, is su-perior in abrasion resistance and yet gives rise to no sharp reduction in number of rotations in continuous operation of the motor, and a process for producing said friction mate-rial composition.
The present friction material composition comprises at least a polyacrylonitrile-based carbon fiber, a fiber component other than said polyacrylonitrile-based carbon fiber, and a thermosetting resin; and the present process for producing a friction material composition comprises dis-persing, in a dispersing medium, at least a polyacryloni-trile-based carbon fiber, a fiber component other than said polyacrylonitrile-based carbon fiber, and a thermosetting resin, filtering the dispersion through a filter material, and subjecting the sheet-shaped material remaining on the filter material to molding under heating and pressure.
The present friction material composition comprises at least a polyacrylonitrile-based carbon fiber, a fiber component other than said polyacrylonitrile-based carbon fiber, and a thermosetting resin; and the present process for producing a friction material composition comprises dis-persing, in a dispersing medium, at least a polyacryloni-trile-based carbon fiber, a fiber component other than said polyacrylonitrile-based carbon fiber, and a thermosetting resin, filtering the dispersion through a filter material, and subjecting the sheet-shaped material remaining on the filter material to molding under heating and pressure.
Description
7~057-21 FRICTION MATERIAli COMPOSITION AND PROCESS FOR PP~O~UCTION
THER~3OF
Field of ~he Invention The present invention relates to a friction material composition which i5 suitably mounted on the contact fric-~ion surface of an ultrasonic motor, as well as to a process for producing said friction material composition.
Background of the Invention Ultrasonic motors are cons-tituted and operated as follows. A piezoelectric ceramic is attached to an elastlc vibrator, an ultrasonic voltage is applied to the pieæoelec-tric ceramic to excite the elastic vibrator to allow the vi-brator to give rise to ultrasonic vibration; and the ultra-sonic vibration is ~ransmitted hy a contact-friction force, to a movement pres~ure-contacted with the elastic vibrator, to obtain a driving force.
There~ore, the state of the contact friction between the ela~tic vibrator and the movement is an important factor in determining the properties of ultrasonic motor, such as output torque, number of rotations, input/output efficiency, ~0 life and the like.
It was proposed in Japanese Patent Publication Kokai(Laid-Open) No. 23585/1987 that an ultrasonic motor having a ~table state of contact friction can be obtained by mounting a fric~ion material composition on the contact-friction surface of the elastic vibrator or movement. Such ,, ~ . .. . .......
. .
. .. ~ .
-: . . : . .
.
" , ' ' :
THER~3OF
Field of ~he Invention The present invention relates to a friction material composition which i5 suitably mounted on the contact fric-~ion surface of an ultrasonic motor, as well as to a process for producing said friction material composition.
Background of the Invention Ultrasonic motors are cons-tituted and operated as follows. A piezoelectric ceramic is attached to an elastlc vibrator, an ultrasonic voltage is applied to the pieæoelec-tric ceramic to excite the elastic vibrator to allow the vi-brator to give rise to ultrasonic vibration; and the ultra-sonic vibration is ~ransmitted hy a contact-friction force, to a movement pres~ure-contacted with the elastic vibrator, to obtain a driving force.
There~ore, the state of the contact friction between the ela~tic vibrator and the movement is an important factor in determining the properties of ultrasonic motor, such as output torque, number of rotations, input/output efficiency, ~0 life and the like.
It was proposed in Japanese Patent Publication Kokai(Laid-Open) No. 23585/1987 that an ultrasonic motor having a ~table state of contact friction can be obtained by mounting a fric~ion material composition on the contact-friction surface of the elastic vibrator or movement. Such ,, ~ . .. . .......
. .
. .. ~ .
-: . . : . .
.
" , ' ' :
2~90~59 72057-21 a friction material composi~ion mu~t have properties such as:
1. ~mall in the abrasion caused by contact friction (larg~ abrasion resistance), 2. the frictional coefficient ~ i5 stable and large, 3. low in property deterioration and stable over a long period of time, and 4. no ~riction sound is generated.
In order to improve the abrasion resistance of a friction material composition, addition of a carbon fiber to the friction material composition was propo~ed in, for exam-ple, ~apanese Patent Publication ~okai (Laid-Open) ~os.
147978/1987 and 255483/1989. When ~uch a conventional fric-tion material composition containing a carbon fiber is used lS in an ultrasonic motor and the re~ulting ultrasonic motor is ~ubjected to continuous operation, however, there occurs a phenomenon in which the number of rotations of the ultra-sonic motor is significantly reduced for few to several min-utes a~ the particular ~imings determined by the kind of the carbon fiber.
An object of the present invention is to provide a friction material composition which iB free from the above problem~ of the prior art and, when used in an ultrasonic motor, is superior in abrasion resistance and gives no sharp reduction in num~er of rotations in continuous operation of the motor, and a process for producing ~uch a friction mate-rial composition.
~n o.rder to develop ~he above friction material com-position, tha pre~ent inventor made an extensive study on , :
~ ~9 ~ ~ 9 72057-21 various compositions. As a result, the present inventor found that a composition comprising a polyacrylonitrile-based carbon fiber as a component gives good results. Thi~
finding has led to the completion of the present invention.
Summary of the Invention Accor~ing to the present invention, there is pro-vided a friction material composition which comprises at least a polyacrylonitrile-based carbon fiber, a fiber compo-nen~ other than the polyacrylonitrile-based carbon fiber, and a thermosetting resin.
The pre~ent invention further provides a process for producing a friction material composition, which comprises dispersing, in a dispersing medium, at lea;~st a polyacryloni-trile-based carbon fiber, a fiber component other than the polyacrylonitrile-based carbon fiber, and a thermasetting resin, filtering the dispersion through a filter material, and subjecting the sheet-shaped material remaining on the filter material to moldin~ under heating and pressure.
Brief Description of the Drawings Fig. 1 is a graph showing the change of number of rotations with ~ime when the friction material composition of Example 1 was used in an ultrasonic motor and the motor ~5 wa~ subjected to a continuous operation of 300 hours.
Fig. 2 is a graph ~howing the change of number of rotations with time when the friction material composition of Comparative E~ample 1 wa~ used in an ultrasonic motor and .
, 2 ~ 9 ~ ~ ~ 9 720~7-21 the motor was subjected to a continuous operation of 300 hours.
Fig. 3 is a graph showing the change of number of rotations with time when the friction material cornposition of Comparative Example 2 was used in an ultrasonic motor and the motor was subjected to a continuous operation of 300 hours.
Detailed Description of the Invention The present invention is hereinafter described in detail.
Since the present friction material composition is characterized by comprising a polyacrylonitrile-based carbon fiber, the polyacrylonitrile-based carbon fiber is explained.
The polyacrylonitrile-based carbon fiber is produced by first producing a polyacrylonitrile fiber by a known method and then subjecting the fiber to a treatment for flame resistance and subsequent carbonization.
The polyacrylonitrile-based carbon fiber preferably has a fiber length of 1 mm or more. A fiber length up to few to several tens of meters can be used, but preferably the length is up to about 40 mm. The carbon fiber has no restriction for the diameter which is generally 30 ~m or less. A more preferred range of the length of the polyacrylonitrile-based carbon fiber is l to 10 mm.
, , . . , : ' , , :. . : ., 2 ~ ~ O ~ ~ 9 72057-21 The present friction material composition further comprises a fiber component other than the polyacrylonitrile-based carbon fiber. The other fiber componen-ts may be any known fibers such as aromatic polyamide fiber, phenolic fiber, polyacrylonitrile fiber, rock wool fiber and the like.
Fihrillated fibers obtained by grinding and crushing such fiber may also be used. Of these fibers, an aroma-tic polyamide fiber is particularly preferable in 4a : ' ' , . ~ ' ' ' ,,;,: , ', ~ ' :'' ' ' ,~ 20~0éj59 view of the preventability for ~he disintegration during handling.
The present friction material composition further-more comprises a thermoset~ing resin. As the thermosetting resin, there i9 mentioned at least one resin selected from known thermosetting resins such as polyimide resin, phenolic resin, rubber-modified phenolic resin, epoxy resin, urea resin, polyurethane resin and the like. ~he thermose~ting resin has no particular restriction, but particularly preferable are a polyimide resin, a phenolic resin and a rubber~modified phenolic resin.
In the present friction material composition, there can be used, as necessary, a friction coefficient modifier such as carbon black, yraphite, fluorinated graphite, sulfu-rized molybdenuml melamine powder, cashew dust or the like.
The proportions of the polyacrylonitrile-based car-bon fiber, the fiber component other than the polyacryloni-trile-based carbon fiber, and the thermosetting resin in the present friction material composition are, for example, 5-60~ by volume, preferably 10-~0% by volume, 2-75% by volume, preferably 3-20% by volume, and 20-80% by volume, preferably 30-50% by volume, respectively.
When the proportion of the polyacrylonitrile-based carbon fiber is less than 5% by volume, there can be ob tained no effect brought about by the use of the polyacry-lonitrile-based carbon fiber. When the proportion is more than 60% by volume, the re~ulting friction material compo~i-tion has voids in which the resin i~ not present suffi-ciently. When the proportion o the fiber component other .
' .... .
~09~9 than the polyacrylonitrile-based carbon fiber i5 less than 2% by ~olume, the sheet-shaped material obkained by ~ilter-ing may be disintegrated during the handling. Meanwhile, the maximum proportion of said fiber component is 75% by volume in view of the reguired proportions of ~he other com-ponents. When the propor-tion of the thermosetting resin is less than 20% by volume, the resulting friction material compo~ition has voids in which the resin is not present suf-ficiently. When the proportion of the resin is more than 80% by volume, the resin leaks through the interface between male die and female die, making it difficult to obtain the required composition.
The present friction material composi~ion having the above-mentioned constitution can be produced by the present process described below.
First, the raw materials are weighed so as to give the above-mentioned component proportions. Then, they are dispersed in an appropriate dispersing medium. In this case, there is no restriction as to the stirrer.
Thereafter, the dispersion is filtered through a filter ma-terial to obtain a sheet-shaped material. As the filter ma-terial, there can be used an appropriate material such as filter cloth, filter paper or the like, but there is pre-ferred a filter material of low filtering loss, capable of collecting thereon the raw materials in the dispersion, in a high recovery ratio. It i8 possible to adopt reduced-pres~
sure filtration in order to shorten the filtering time.
The dispersing medium is required to be a liquid at room temperature and not to dissolve the components of the ~ .
, :- . ' ' ~ ' " ' : ;
,~. . . . .
: .: . .
- 2 ~ 9 72057-21 pre~ent friction material compo~ition. For ~xample, water is u~ed as the dispersing medium.
The sheet-~haped material obtained by filtration is then dried. Since in this step it is sufficient if water iq removed, drying, for example, at 60C for about one night is sufficient. The dried sheet-shaped material is subjected to molding under heating and pressure, whereby a friction mate-rial composi~ion according to the present invention can be obtained. The conditions of heating and pressure are, for example, 200-220C, 10-30 minutes and 200 kgf~cm2 when the thermosetting resin is a polyimide resin, and 150-170C, 10-30 minutes and 200 kgf/cm2 when the thermosetting resin is a phenolic resin.
The present invention i~ hereinafter described in more detail referring to Example~.
Example 1 In water was dispersed a compo~ition comprising 20%
by volume of a polyacrylonitrile-based carbon fiber [TORAYCA
CHOPPED FIBER T010 (trade-mark ), a product of TORAY
INDUSTRIESI INC., fiber length = 6 mm], 20% by volume of an aromatic polyamide fiber pulp [REVLAR (trade-mark), a prod~
uct of TORAY DuPont] and 60% by volume of a polyimide [ TECHMIGHT (trade-mark), a product of Mitsui P~trochemical Industries,Ltd.]o The resulting dispersion was filtered to obtain a shee~shaped material. The sheet-shaped material was dried at 60C for one night. The dried material was treated at 200 kgf/cm2 at 220C for 10 minutes to produce a friction material composition of the present invention.
, ,;
- ~ .
.
, Compara~ive Example 1 A composition was subjected to the same treatment as in E~ample 1 except that the polyacrylonitrile-based carbon fiber used in the composition of E~ample 1 was replaced by a pitch-based carbon fiber [RURECA CHOP C103S (trade-mark), a product of ~ureha Chemical Industry Co., Ltd~, fiber length = 3 mm]~ to obtain a friction material compo~ition for com-parison.
Comparative E~ample 2 A compo~ition was subjected to the ~ame treatment as in E~ample 1 except that the polyacrylonitrile-based carbon fiber used in the composition of Example 1 was replaced by a phenol-based carbon fiber lRYNO~ (trade mark), a product of Gun-ei Ragaku, fiber length - 6 mm], to obtain a friction material composition for comparison.
Each of the above-obtained fric~ion material compo-~i~ions was used in an ultrasonic motor [USM 40D, a product of Matsushita Electric Industrial Co., ~td.] and tested.
That i~, the motor was subjected to 20-hour aging (load-free operation) and then to 300-hour continuous opera-tion under a load of 200 gf-cm. The changes of number of rotation~ with time are shown in Figs. 1 ~o 3.
A~ is clear from Fig. 1, when the friction material composition of E~ample 1 wa~ used, the number o~ rotations showed no sharp reduction for 100 hour~ and was stable.
,.,.. ", . . ;
.
. . .,, .. . ~ :, . "
2~ jS9 In con~rast, when the friction material compositions of Comparative E~amples 1 and 2 were used, as is clear from Figs. 2 and 3, the number of rotations showed sharp reduc-tion several times each for several minutes in khe time pe-riod of 10 hours in the case of the friction material compo-~ition of Comparative Example 1, and there was frequent al-ternation of fast rotation and slow rotation even in the ~ime period of one hour in the case of the friction material composition of Comparative Example 2.
The friction material composition of the present in-vention comprises at least a polyacrylonitrile based carbon fiber, a fiber component other than said polyacrylonitrile-based carbon fiber, and a thermosetting resin, and has ex-cellent abrasion resistance and yet gives rise to no sharp reduction in number of rotations during continuous opera-tion.
The reasons for these effects are considered to be that while a pitch-based carbon fiber or the like, when worn, genera~e3 a hard powder and invites reduction in num-ber of rotations by acting like rollers, the polyacryloni-trile-based carbon fiber, when worn, generates a very fine or soft powder and invites no reduction in number of rota-tions .
... .
. . , ' ,
1. ~mall in the abrasion caused by contact friction (larg~ abrasion resistance), 2. the frictional coefficient ~ i5 stable and large, 3. low in property deterioration and stable over a long period of time, and 4. no ~riction sound is generated.
In order to improve the abrasion resistance of a friction material composition, addition of a carbon fiber to the friction material composition was propo~ed in, for exam-ple, ~apanese Patent Publication ~okai (Laid-Open) ~os.
147978/1987 and 255483/1989. When ~uch a conventional fric-tion material composition containing a carbon fiber is used lS in an ultrasonic motor and the re~ulting ultrasonic motor is ~ubjected to continuous operation, however, there occurs a phenomenon in which the number of rotations of the ultra-sonic motor is significantly reduced for few to several min-utes a~ the particular ~imings determined by the kind of the carbon fiber.
An object of the present invention is to provide a friction material composition which iB free from the above problem~ of the prior art and, when used in an ultrasonic motor, is superior in abrasion resistance and gives no sharp reduction in num~er of rotations in continuous operation of the motor, and a process for producing ~uch a friction mate-rial composition.
~n o.rder to develop ~he above friction material com-position, tha pre~ent inventor made an extensive study on , :
~ ~9 ~ ~ 9 72057-21 various compositions. As a result, the present inventor found that a composition comprising a polyacrylonitrile-based carbon fiber as a component gives good results. Thi~
finding has led to the completion of the present invention.
Summary of the Invention Accor~ing to the present invention, there is pro-vided a friction material composition which comprises at least a polyacrylonitrile-based carbon fiber, a fiber compo-nen~ other than the polyacrylonitrile-based carbon fiber, and a thermosetting resin.
The pre~ent invention further provides a process for producing a friction material composition, which comprises dispersing, in a dispersing medium, at lea;~st a polyacryloni-trile-based carbon fiber, a fiber component other than the polyacrylonitrile-based carbon fiber, and a thermasetting resin, filtering the dispersion through a filter material, and subjecting the sheet-shaped material remaining on the filter material to moldin~ under heating and pressure.
Brief Description of the Drawings Fig. 1 is a graph showing the change of number of rotations with ~ime when the friction material composition of Example 1 was used in an ultrasonic motor and the motor ~5 wa~ subjected to a continuous operation of 300 hours.
Fig. 2 is a graph ~howing the change of number of rotations with time when the friction material composition of Comparative E~ample 1 wa~ used in an ultrasonic motor and .
, 2 ~ 9 ~ ~ ~ 9 720~7-21 the motor was subjected to a continuous operation of 300 hours.
Fig. 3 is a graph showing the change of number of rotations with time when the friction material cornposition of Comparative Example 2 was used in an ultrasonic motor and the motor was subjected to a continuous operation of 300 hours.
Detailed Description of the Invention The present invention is hereinafter described in detail.
Since the present friction material composition is characterized by comprising a polyacrylonitrile-based carbon fiber, the polyacrylonitrile-based carbon fiber is explained.
The polyacrylonitrile-based carbon fiber is produced by first producing a polyacrylonitrile fiber by a known method and then subjecting the fiber to a treatment for flame resistance and subsequent carbonization.
The polyacrylonitrile-based carbon fiber preferably has a fiber length of 1 mm or more. A fiber length up to few to several tens of meters can be used, but preferably the length is up to about 40 mm. The carbon fiber has no restriction for the diameter which is generally 30 ~m or less. A more preferred range of the length of the polyacrylonitrile-based carbon fiber is l to 10 mm.
, , . . , : ' , , :. . : ., 2 ~ ~ O ~ ~ 9 72057-21 The present friction material composition further comprises a fiber component other than the polyacrylonitrile-based carbon fiber. The other fiber componen-ts may be any known fibers such as aromatic polyamide fiber, phenolic fiber, polyacrylonitrile fiber, rock wool fiber and the like.
Fihrillated fibers obtained by grinding and crushing such fiber may also be used. Of these fibers, an aroma-tic polyamide fiber is particularly preferable in 4a : ' ' , . ~ ' ' ' ,,;,: , ', ~ ' :'' ' ' ,~ 20~0éj59 view of the preventability for ~he disintegration during handling.
The present friction material composition further-more comprises a thermoset~ing resin. As the thermosetting resin, there i9 mentioned at least one resin selected from known thermosetting resins such as polyimide resin, phenolic resin, rubber-modified phenolic resin, epoxy resin, urea resin, polyurethane resin and the like. ~he thermose~ting resin has no particular restriction, but particularly preferable are a polyimide resin, a phenolic resin and a rubber~modified phenolic resin.
In the present friction material composition, there can be used, as necessary, a friction coefficient modifier such as carbon black, yraphite, fluorinated graphite, sulfu-rized molybdenuml melamine powder, cashew dust or the like.
The proportions of the polyacrylonitrile-based car-bon fiber, the fiber component other than the polyacryloni-trile-based carbon fiber, and the thermosetting resin in the present friction material composition are, for example, 5-60~ by volume, preferably 10-~0% by volume, 2-75% by volume, preferably 3-20% by volume, and 20-80% by volume, preferably 30-50% by volume, respectively.
When the proportion of the polyacrylonitrile-based carbon fiber is less than 5% by volume, there can be ob tained no effect brought about by the use of the polyacry-lonitrile-based carbon fiber. When the proportion is more than 60% by volume, the re~ulting friction material compo~i-tion has voids in which the resin i~ not present suffi-ciently. When the proportion o the fiber component other .
' .... .
~09~9 than the polyacrylonitrile-based carbon fiber i5 less than 2% by ~olume, the sheet-shaped material obkained by ~ilter-ing may be disintegrated during the handling. Meanwhile, the maximum proportion of said fiber component is 75% by volume in view of the reguired proportions of ~he other com-ponents. When the propor-tion of the thermosetting resin is less than 20% by volume, the resulting friction material compo~ition has voids in which the resin is not present suf-ficiently. When the proportion of the resin is more than 80% by volume, the resin leaks through the interface between male die and female die, making it difficult to obtain the required composition.
The present friction material composi~ion having the above-mentioned constitution can be produced by the present process described below.
First, the raw materials are weighed so as to give the above-mentioned component proportions. Then, they are dispersed in an appropriate dispersing medium. In this case, there is no restriction as to the stirrer.
Thereafter, the dispersion is filtered through a filter ma-terial to obtain a sheet-shaped material. As the filter ma-terial, there can be used an appropriate material such as filter cloth, filter paper or the like, but there is pre-ferred a filter material of low filtering loss, capable of collecting thereon the raw materials in the dispersion, in a high recovery ratio. It i8 possible to adopt reduced-pres~
sure filtration in order to shorten the filtering time.
The dispersing medium is required to be a liquid at room temperature and not to dissolve the components of the ~ .
, :- . ' ' ~ ' " ' : ;
,~. . . . .
: .: . .
- 2 ~ 9 72057-21 pre~ent friction material compo~ition. For ~xample, water is u~ed as the dispersing medium.
The sheet-~haped material obtained by filtration is then dried. Since in this step it is sufficient if water iq removed, drying, for example, at 60C for about one night is sufficient. The dried sheet-shaped material is subjected to molding under heating and pressure, whereby a friction mate-rial composi~ion according to the present invention can be obtained. The conditions of heating and pressure are, for example, 200-220C, 10-30 minutes and 200 kgf~cm2 when the thermosetting resin is a polyimide resin, and 150-170C, 10-30 minutes and 200 kgf/cm2 when the thermosetting resin is a phenolic resin.
The present invention i~ hereinafter described in more detail referring to Example~.
Example 1 In water was dispersed a compo~ition comprising 20%
by volume of a polyacrylonitrile-based carbon fiber [TORAYCA
CHOPPED FIBER T010 (trade-mark ), a product of TORAY
INDUSTRIESI INC., fiber length = 6 mm], 20% by volume of an aromatic polyamide fiber pulp [REVLAR (trade-mark), a prod~
uct of TORAY DuPont] and 60% by volume of a polyimide [ TECHMIGHT (trade-mark), a product of Mitsui P~trochemical Industries,Ltd.]o The resulting dispersion was filtered to obtain a shee~shaped material. The sheet-shaped material was dried at 60C for one night. The dried material was treated at 200 kgf/cm2 at 220C for 10 minutes to produce a friction material composition of the present invention.
, ,;
- ~ .
.
, Compara~ive Example 1 A composition was subjected to the same treatment as in E~ample 1 except that the polyacrylonitrile-based carbon fiber used in the composition of E~ample 1 was replaced by a pitch-based carbon fiber [RURECA CHOP C103S (trade-mark), a product of ~ureha Chemical Industry Co., Ltd~, fiber length = 3 mm]~ to obtain a friction material compo~ition for com-parison.
Comparative E~ample 2 A compo~ition was subjected to the ~ame treatment as in E~ample 1 except that the polyacrylonitrile-based carbon fiber used in the composition of Example 1 was replaced by a phenol-based carbon fiber lRYNO~ (trade mark), a product of Gun-ei Ragaku, fiber length - 6 mm], to obtain a friction material composition for comparison.
Each of the above-obtained fric~ion material compo-~i~ions was used in an ultrasonic motor [USM 40D, a product of Matsushita Electric Industrial Co., ~td.] and tested.
That i~, the motor was subjected to 20-hour aging (load-free operation) and then to 300-hour continuous opera-tion under a load of 200 gf-cm. The changes of number of rotation~ with time are shown in Figs. 1 ~o 3.
A~ is clear from Fig. 1, when the friction material composition of E~ample 1 wa~ used, the number o~ rotations showed no sharp reduction for 100 hour~ and was stable.
,.,.. ", . . ;
.
. . .,, .. . ~ :, . "
2~ jS9 In con~rast, when the friction material compositions of Comparative E~amples 1 and 2 were used, as is clear from Figs. 2 and 3, the number of rotations showed sharp reduc-tion several times each for several minutes in khe time pe-riod of 10 hours in the case of the friction material compo-~ition of Comparative Example 1, and there was frequent al-ternation of fast rotation and slow rotation even in the ~ime period of one hour in the case of the friction material composition of Comparative Example 2.
The friction material composition of the present in-vention comprises at least a polyacrylonitrile based carbon fiber, a fiber component other than said polyacrylonitrile-based carbon fiber, and a thermosetting resin, and has ex-cellent abrasion resistance and yet gives rise to no sharp reduction in number of rotations during continuous opera-tion.
The reasons for these effects are considered to be that while a pitch-based carbon fiber or the like, when worn, genera~e3 a hard powder and invites reduction in num-ber of rotations by acting like rollers, the polyacryloni-trile-based carbon fiber, when worn, generates a very fine or soft powder and invites no reduction in number of rota-tions .
... .
. . , ' ,
Claims (12)
1. A friction material composition which com-prises at least a polyacrylonitrile-based carbon fiber, a fiber component other than said polyacrylonitrile-based car-bon fiber, and a thermosetting resin.
2. A friction material composition according to Claim 1, wherein the polyacrylonitrile-based carbon fiber has a fiber length of 1 mm or more.
3. A friction material composition according to Claim 1, wherein the fiber component other than the poly-acrylonitrile-based carbon fiber is an aromatic polyamide fiber, a phenolic fiber, a polyacrylonitrile fiber or a rock wool fiber.
4. A friction material composition according to Claim 1, wherein the thermosetting resin is a polyimide resin, a phenolic resin, a rubber-modified phenolic resin, an epoxy resin, a urea resin or a polyurethane resin.
5. A friction material composition according to Claim 1, wherein the contents of the polyacrylonitrile-based carbon fiber, the fiber component other than the polyacry-lonitrile-based carbon fiber and the thermosetting resin are 5-60% by volume, 2-75% by volume and 20-80% by volume, re-spectively.
6. A process for producing a friction material composition, which comprises dispersing, in a dispersing medium, at least a polyacrylonitrile-based carbon fiber, a fiber component other than said polyacrylonitrile-based car-bon fiber, and a thermosetting resin, filtering the disper-sion through a filter material, and subjecting the sheet-shaped material remaining on the filter material to molding under heating and pressure.
7. A process for producing a friction material composition according to claim 6, wherein the dispersing medium is water.
8. A friction material composition of a sheet shape to be mounted on a contact-friction surface of an ultrasonic motor, wherein the friction material composition is produced by molding under heat and pressure a uniformly dispersed resin-fiber mixture comprising:
(A) 5 to 60% by volume of a polyacrylonitrile-based carbon fiber;
(B) 2 to 75% by volume of at least one other fiber selected from the group consisting of aromatic polyamide fiber, phenolic fiber, polyacrylonitrile fiber and rock wool fiber;
and (C) 20 to 80% by volume of a thermosetting resin selected from the group consisting of polyimide resin, phenolic resin, rubber-modified phenolic resin, epoxy resin, urea resin and polyurethane resin.
(A) 5 to 60% by volume of a polyacrylonitrile-based carbon fiber;
(B) 2 to 75% by volume of at least one other fiber selected from the group consisting of aromatic polyamide fiber, phenolic fiber, polyacrylonitrile fiber and rock wool fiber;
and (C) 20 to 80% by volume of a thermosetting resin selected from the group consisting of polyimide resin, phenolic resin, rubber-modified phenolic resin, epoxy resin, urea resin and polyurethane resin.
9. A friction material composition according to claim 8, in which the mixture further comprises a friction coefficient modifying effective amount of at least one member selected from the group consisting of carbon black, graphite, fluorinated graphite, sulfurized molybdenum, melamine powder and cashew dust.
10. A friction material composition according to claim 8, wherein the other fiber (B) is aromatic polyamide fiber.
11. A friction material composition according to claim 8, wherein the thermosetting resin (C) is a polyimide resin.
12
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4078326A JPH05239442A (en) | 1992-02-28 | 1992-02-28 | Friction material composition and its production |
| JP04-078326 | 1992-02-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2090559A1 true CA2090559A1 (en) | 1993-08-29 |
Family
ID=13658847
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002090559A Abandoned CA2090559A1 (en) | 1992-02-28 | 1993-02-26 | Friction material composition and process for production thereof |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0557905A1 (en) |
| JP (1) | JPH05239442A (en) |
| KR (1) | KR930018005A (en) |
| CA (1) | CA2090559A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5508109A (en) * | 1993-10-06 | 1996-04-16 | Avco Corporation | Fiber blend for low cost, asbestos free friction material |
| US5573579A (en) * | 1994-03-17 | 1996-11-12 | Osaka Gas Company, Ltd. | Method for producing friction material |
| ES2133626T3 (en) * | 1994-08-09 | 1999-09-16 | Sterling Chemicals Int | DRY PROCESSED FRICTION MATERIAL, MANUFACTURING METHOD THEREOF AND DRY MIXTURE. |
| US5520866A (en) * | 1994-08-09 | 1996-05-28 | Cytec Technology Corp. | Process for the preparation of friction materials containing blends of organic fibrous and particulate components |
| IN183563B (en) * | 1994-08-09 | 2000-02-12 | Sterling Chemicals Internat In | |
| AU702352B2 (en) * | 1994-08-09 | 1999-02-18 | Sterling Chemicals International, Inc. | Asbestos-free gaskets and the like containing blends of organic fibrous and particulate components |
| AT501730B1 (en) * | 2002-10-14 | 2006-11-15 | Miba Frictec Gmbh | FRICTION LINING |
| US7537824B2 (en) * | 2002-10-24 | 2009-05-26 | Borgwarner, Inc. | Wet friction material with pitch carbon fiber |
| US8021744B2 (en) | 2004-06-18 | 2011-09-20 | Borgwarner Inc. | Fully fibrous structure friction material |
| US8603614B2 (en) | 2004-07-26 | 2013-12-10 | Borgwarner Inc. | Porous friction material with nanoparticles of friction modifying material |
| US7429418B2 (en) | 2004-07-26 | 2008-09-30 | Borgwarner, Inc. | Porous friction material comprising nanoparticles of friction modifying material |
| DE102008013907B4 (en) | 2008-03-12 | 2016-03-10 | Borgwarner Inc. | Frictionally-locking device with at least one friction plate |
| CN103911118A (en) * | 2014-04-01 | 2014-07-09 | 南京航空航天大学 | Polyimide friction material for rotary ultrasonic motor and preparation method of polyimide friction material |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4256801A (en) * | 1979-12-14 | 1981-03-17 | Raybestos-Manhattan, Incorporated | Carbon fiber/flame-resistant organic fiber sheet as a friction material |
| JPS56103270A (en) * | 1980-01-22 | 1981-08-18 | Teijin Ltd | Friction material |
| EP0129022A3 (en) * | 1983-04-25 | 1986-01-02 | Borg-Warner Corporation | Process for making dry friction material |
| DE3533624C1 (en) * | 1985-09-20 | 1987-05-27 | Frenzelit Werke Gmbh & Co Kg | Process for producing friction linings and friction linings produced therewith |
| JP2782105B2 (en) * | 1990-02-14 | 1998-07-30 | 曙ブレーキ工業株式会社 | Non-asbestos friction material |
| JP2838304B2 (en) * | 1990-02-23 | 1998-12-16 | 日清紡績株式会社 | Non-asbestos friction material |
-
1992
- 1992-02-28 JP JP4078326A patent/JPH05239442A/en active Pending
-
1993
- 1993-02-19 EP EP93102670A patent/EP0557905A1/en not_active Withdrawn
- 1993-02-22 KR KR1019930002439A patent/KR930018005A/en not_active Application Discontinuation
- 1993-02-26 CA CA002090559A patent/CA2090559A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05239442A (en) | 1993-09-17 |
| EP0557905A1 (en) | 1993-09-01 |
| KR930018005A (en) | 1993-09-21 |
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