CA2179487A1 - Polyimide composition having improved properties - Google Patents
Polyimide composition having improved propertiesInfo
- Publication number
- CA2179487A1 CA2179487A1 CA 2179487 CA2179487A CA2179487A1 CA 2179487 A1 CA2179487 A1 CA 2179487A1 CA 2179487 CA2179487 CA 2179487 CA 2179487 A CA2179487 A CA 2179487A CA 2179487 A1 CA2179487 A1 CA 2179487A1
- Authority
- CA
- Canada
- Prior art keywords
- polyimide
- parts
- weight
- graphite
- friction
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/02—Fibres or whiskers
- C08K7/04—Fibres or whiskers inorganic
- C08K7/06—Elements
Abstract
Polyimide compositions containing natural graphite powder, along with carbon or graphite fiber, exhibit an unusual combination of low wear and friction and low coefficient of thermal expansion.
Description
2 1 79487 .~,I/U.~ /J
r ~ 1 ~
~LE;
POLYIMIDE COMPOSITION HAVING IMPROVED PROPERTIES
I~ACKGROUNn Q~ TllF INV~.~TIQN
S Polyimide ~ f ~ , such as those described in Edwards, U.S.
Patent 3,179,614, can be used in a wide variety of ~ r~ ~
The, 7 ~ rl l~ t~ia~ of polyimide ~ llc under stress and at high l~ d~ul ~ s have made them useful in the form of bushings, seals, electrical insulators, I,u~.~,ul ~aaul vanes and impellers, pistons and piston rings, gears, thread guides, cams, bMke linings, and clutch faces.
It is often desirable to I,u,~l~; various additives in such polyimide . , before f~ - into their final form.
Accordingly, graphite has been ill~vl~u~alC~ ~o improve the wear of such ~ ... ,. -- ~ ;f~- ~ in bearing -l~ Diamonds have 15 beeni,~ ,uuldt.~forabrasive ~ ;f. ~ r u,u~ havebeen ill~UllUUI ~t- d in the past for lubricity in forming and extrusion of shapes.
Despite the variety of polyimide, . and additives that have previously been available, a continuing need for polyimide I ~ ,u~- Ii-ul~ly when processed into the shape of bushings and 20 bearings, is a reduction in the thermal expansion of such materials. Jn bushinf,s and bearings, close clearances to adjacent metal surfaces are needed, in ~,. .---~. .~r;f ~ with excellent wear ~ ~l..,.l.t~ lics. U.S. patent5,284,904 disdoses polyimide, ~ containing graphite powder and ~ ll e, said . . having both low wear and friction 25 p- ru~ - and a low coefficient of thermal expansion. However, it is still desirous to continue to develop other and better polyimide ~
having both lowwear and friction p~ r(.. . - < and a low foefficient of thermal expansion.
In the present invention, it was found that a polyimide 30 ~ - contai~ing natural graphite povider, a10ng with carbon or graphite fiber filler, exhibits greatly reduced thermal expansion compared to the same ~ containing no fiber filler. The I also was found to exhibit low wear and friction ~,~lru. against a steel mating surface, superior to the same < u- - ~ containing no fibrous carbon or 35 gr~phi~filler l~contr,s~ fi~olyim~de~ o~hcabove-WO 95/20005 ~ r~ ~ S
referenced U.S. patent ~ ;- - are taught to be, with respect to wear and friction p r ~ against a steel mating surface, only equivalent to the same ~ without ~.. " "
SUIVIMARY OF THE INVF.l~llON
S The present invention provides a polyimide ~. . ~I.. .- :~;- - .
comprised of f - -~' ' quantities of (a) about 8-69 parts by weight of at least one polyimide, (b) about 30-80 parts by weight of natural graphite powder, and (c) about 1-12 parts by weight of carbon or graphite fibrous filler.
DETAlT,T~.n DE~:KII- I ION O~ l~TT''. INVF.~TION
The ~ of the present invention contain about 8-69 parts by weight of at lear.t one polyimide and preferably about 3~56 parts by weight. Parts by weight, as used herein, are indicated as parts per 100 parts of the total weight of the polyimide, the natural graphite powder, and the carbon or graphite fibrous filler. A wide variety of pfJI~ ' ' ' can be used, including those described in Edwards, U.S. Patent 3,179,614, hereby ihl"f~ ulut~ d by reference. The pf,l~ ' '' described therein are prepared from at least one diamine and at least one anhydride. Preferred diamines which can be used include m, ' ~ h .lf, diamine (MPD), p, ' ,' diamine (PPD), UA~I-' "' ~ (ODA), methylene dianiline (MDA) and toluene diamine (TDA). Preferred ~ cs which can be used include . ' - t. l,~.,~.l,, ,"- ~" ' ,.l,id~ (BTDA), biphenyl " ' ~ c (BPDA), trimellitic anhydride (TMA), ~" ., " ' ' - ~ " ~ I,;dc (PMDA), maleic anhydride (MA) and nadic anhydride (NA).
25 ' Preferred pfJI~' ' ' which can be used in the present invention include those prepared from the following, ' ' of anhydride and diamine: BTDA-MPD, MA-MDA, BTDA-TDA-MDA, BTDA-MDA-NA, TMA-MPD & TMA-ODA, BPDA-ODA & BPDA-PPD, BTDA-4,4'-~-' ' ' ,' ~,andBTDA-bis(p- ' r~ ~)-p,p'-biphenyl. An especially s.,li ~L~ tuly polyimide useful in the present invention is that prepared from 1".~' ~""'~ ~" 'l~,dli~C and 4,4'-UA;.-' "' The polyimide . ' ' of the present invention also contain about 30-80 parts by weight of natural graphite powder. Less than about 30 parts by weight of the natural graphite powder could ~ '~ dimirlish the frictional properties required for bushing and bearing _. r Gre~er than about 80 parts byweight of the natllral graphite powder ma ~ WO9512000~; ~,IILJ.. _~ Izi result in a d~ ;aliull of the structural integrity of the final product and loss of the . ~ rn~.c,~ni~ l properties for which p~l~ ' are noted. Preferably, the natural graphite powder comprises about 40-70 parts by weight.
The graphite powde~ used in the . . of the present invention is naturally-occurring. Natural graphite powder, in ~
with carbon or graphite flber in the specifed provides reduced wear and friction. For contrast, when all .., ' '~ produced graphites are used in ' with carbon or graphitc fiber in a 10 polyimide ~ ;- the wear and friction properties of the ~ ';v are increased A central feature of the . , - of the present invention is the i... u-pv-..liu.. of about 1-12 parts by weight of chopped or milled carbon fiber or graphite fiber. As little as 1 part by weight of the carbon or graphite15 fiber ill~lr ~ into the polyimide ~ r '- will ~i~, '' 1,~ reduce the coefficient of linear thermal expansion of the, as compared to a . ' '- graphite powder/polyimide . In addition, the containing graphite powder along with the carbon or graphite fiber, when tested agair;st a steel mating surface, shows wear and friction 20 p~ ' - superior to a . ' ' - graphite powder/polyimide c~ - - '1"`- ';'"1, even at high PV (pressure x velocity) . " Greater than 12 parts by weight of the carbon or graphite fiber can cause variable friction behavior and can depreciate the overall - ' ' properties of parts made from these . Preferably, about 4-10 parts by weight carbon or 25 graphite fiber is used herein.
The present, . can further contain up to about 10 parts by weight of other additives, fillers and dry lubricants which do not depreciate the overall ps ' ~ of the finished polyimide parts, as will be evident to those skilled in the art. Typical of such additional 30 additives are tungsten disulfide and 'l~L '- disulfide.
In the ~.~, of the present; . the order of additional of: . is not critical. The three basic , (iG, the polyimide, the natural graphite powder, and the carbon or graphite fiber) can be blended using . ' milling i: ' , in the required 35 quantities. In the alt~ , some ~ lly available p~
contain ~ d graphite, to which additional graphite can be added by `` -' +~''? `; } t~
W0 95/20û05 2 ~ 7 q 4 8 7 "o..~ I blending t~ ' . if desired. The natural graphite pDwdcr and carbon or graphite fiber can also be cu.... ~ pu~dt~ d into the polyimide, as an alternative to milling; ~ t ' ~ , by blending into a polymer solution of polyimide precursors prior to ~-~ , as the S polyimide. This lattermost ~ ,c.laliu., technique is preferred.
The polyimide . of the present irlvention, when processed into parts, are suitable for providing wear surfaces in the for~n of bushings and bearings where close clearances to adjacent metal surfaces are needed. These bearings include a multitude of small motûr bearings. Parts formed from the present ~- --- r ' ' ' exhibit a reduced coefficient o~ linear thermal expansion by as much as 25% compared to a . ` ~ n graphite powder/polyimide, , In addition, the ~ . when tested against a steel mating surface, shows wear and friction l ~ superior to a r~ ' ' - graphite powder/polyimide :r ~- 1, even at high PV
(pressure x velocity); The reduction of expansion coefficient exhibited by the . , - of the present invention, whOe improving the wear and friction ~ t~ , appears to be unique in the graphite or carbon fiber/natural graphite powder/polyimide - . of the present invention. Other fibrous fillers, when ~u. ' into the relatively hard graphite powder/polyimide . )n, also lower thermal exparlsion by equivalent amounts, but ohen they are abrasive in nature, causing high friction and excessive wear to the polyimide . and to the steel mating surface. It is surprising, therefore, that the carborl fiber performs well when used in the range within the scope of this invention.
BX~MPJ ~
In each of the examples below, polyimide resins were prepared from pyromellitic ~" ~d-idc and 4,4'-oxydianiline, according to the uCC~h.~ of U.S. Patent 3,179,614 or U.S. Patent 4,622,384. The indicated quantity of graphite powder was uul at~ into the polymer solution prior to u. ~ ;u ~ as the polyimide. S ' , '~" carbon fiber (Toray MLD 300, average length, 130 um, diameter, 7 um) was added to the graphite-filled resin by dry blending. The carbûn fiber may also be added to the polymer solution prior to p-~ , as the polyi~nide. The flber was added to the resin as S weight percent, 10 weight percent, etc., so that the final was less than the added amount. For example, 5 grams of fiber added to 100 grams of a resin ~ ;n- containing 60 weight . .
217~
~ WO 95t2000~ , . 4 8 7 A .~ f :
percent graphite yielded a fiAal product of ~ , ~ 38,1% polyimide, 57.1% graphite, and 4.8% carbon fiber.
The resulting filled polyimide resin powder was converted into test specimens by direct forming at a pressure of 100,000 psi (689 MPa) at 5 room ~ , The resulting parts were sintered for three hours at 400 degrees C under nitrogen at ~ pressure. After cooling to room ~ , the parts were machined to ffnal ' for test r, - The 0.25" (6.35 mm) wide contact surhce of the wear/friction test block was machined to such a curvature that it ~ to the outer 10 ~ of the 1.375~ (34.9 mm) diameter x 0.375r (g.5 mm) viide metal mating ring. The blocks were oven dried and d dry over dessicant until tested.
Wear tests were performed using a ~alex No. 1 Ring and Block Wear and Friction Tester. The .~, , is described in ASTM Test 15 mothod D2714. The polyimide block was mounted against tbe rotating metal ring and loaded against it with the selected test pressure. Rotational velocity of the ring was set at tbe desired speed. No lubricant was used between the mating surfaccs. The rings were SAE 4620 steel, Rc 58-63, 6-12 RMS. A new ring was used for each test. Test time was usually 24 hours, 20 except when friction and wear were high, in which case the test was ~ early.
The coefficient of linear thermal expansion was ~ ~ d by a ~ ' analyzer (ASTM E831). On each specimen it was measured in the direction ~ - ' to the direction of forming pressure 25 when the part was made.
Examples I to 6 and CQmv~r~tive~i xLmvLes A tQ .T (T~ble 1) Wear test results for these examples are at 256 psi (1.77 MPa) pressure and 390 fpm (1.98 m/s) velocity for a PV of ~ P~ 100,000 psi-fpm (3.5 MPa-m/s). Examples 1-5 show the effect of adding carbon fiber 30 on the wear, friction, and coefficient of linear thermal expansion (Cl[E) of a natural graphite-filled polyimide. Specifically, Example 1 and 2 are fromtheadditionof5and 10weightpercent,I~o~
carbon fiber to the ~ , of C: . ~. Example A. All three properties were improved r `~y. Example 3 shows that further 35 illl~l u . . results from an even higher natural graphite content.
Examples 4 and 5 show simDar . u . over the parent i , in WO 9S/2000~ ? S - 6 _ 2 1 7 9 4 8 7 JalaliVC Example B at lower natural graphite content. Example 6 A.. ~: .t~ nt. 5 good results using a natural graphite from a second source.
The addition of carbon fiber to a synthetic graphite in the polyimide ~ . in (' , ~_ Example C similarly improved the 5 CIE, but resulted in very high wear and friction compared with its parent "' ' `I'q~ al a~ Example D. Synthetic graphite from a second source, C~ Jala~ Example E, gave excellent wear and friction results, but these were degraded i" '~ 'y with the addition of carbon f~ber in C~ Jala~i~., Example F.
C . ~i _ Examples G through J show that the addition of higher ~ C~ .-t~ of c&rbon fiber can result in eithervariable friction or very high friction with reduced wear resistance, even when the graphite is natural grade.
W095~20005 ~ '; ``, 2 1 79487 ~ u . ,~
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o ~ c~ o ~ ~ ~ 3 o ,~ ~ X X X - ~ ~ o ~ ~ '~ ~ ~ C
D ~ -- O O -- O O -- ~ O O
ll 11 ll 11 z _ C'~ ~ U Cl ~I~ ~ O ~
.
W0 95/20005 ` ` 2 1 7 9 4 8 7~
Exsmale 7 snd ComDsratiYe Examples K snd L (T ' - 2) Wear test conditions for the tests in Table 2 are the same as for Table 1 (PV = 100,000 psi-fpm). For Example 7 and CO~ a~
Examples K and L, a chopped graphite fiber (Kureha grade 2007S, 5 ~lu d~at~,lj 200 um average length and 20 um diameter) was used in place of the carbor~ fber. Example 7 shows that the CTE can be reduced and good wear and friction test results ~ ' - d when thc graphite flber is combined with natural graphite. ~ . ._ Example K shows that in with synthetic graphite, the graphite fiber gives very high 10 friction. Ccl...y~.-d~ Example L shows that at a higher ~ ~liun of graphite fiber, poor wear and friction results, even when the graphite is the natural grade.
.
wo gs~ooos ; . . 2 1 7 9 4 8 7 ~, ~ 8 ~ _ ~
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,10- ' ExamDles 8 and 9 and Coml~arat~ve EY~mples M nnd N ~able 3) Wear and friction test results for the examples in Table 3 are at 192 psi (1.32 MPa) pressure and 134 fpm (0.68 m/s) for a PV of U,.i~ .t~ 25,000 psi-fpm (0.9 MPa-m/s). Examples 8 and 9 show that 5even at a lower PV, friction F e r ~ iS improved compared with the parent ~u ~ -- in ~ Example M. Wear and friction are both superior compared with C . ._ Example N, in which carbon fiber is combined with synthetic graphite.
.. .
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~LE;
POLYIMIDE COMPOSITION HAVING IMPROVED PROPERTIES
I~ACKGROUNn Q~ TllF INV~.~TIQN
S Polyimide ~ f ~ , such as those described in Edwards, U.S.
Patent 3,179,614, can be used in a wide variety of ~ r~ ~
The, 7 ~ rl l~ t~ia~ of polyimide ~ llc under stress and at high l~ d~ul ~ s have made them useful in the form of bushings, seals, electrical insulators, I,u~.~,ul ~aaul vanes and impellers, pistons and piston rings, gears, thread guides, cams, bMke linings, and clutch faces.
It is often desirable to I,u,~l~; various additives in such polyimide . , before f~ - into their final form.
Accordingly, graphite has been ill~vl~u~alC~ ~o improve the wear of such ~ ... ,. -- ~ ;f~- ~ in bearing -l~ Diamonds have 15 beeni,~ ,uuldt.~forabrasive ~ ;f. ~ r u,u~ havebeen ill~UllUUI ~t- d in the past for lubricity in forming and extrusion of shapes.
Despite the variety of polyimide, . and additives that have previously been available, a continuing need for polyimide I ~ ,u~- Ii-ul~ly when processed into the shape of bushings and 20 bearings, is a reduction in the thermal expansion of such materials. Jn bushinf,s and bearings, close clearances to adjacent metal surfaces are needed, in ~,. .---~. .~r;f ~ with excellent wear ~ ~l..,.l.t~ lics. U.S. patent5,284,904 disdoses polyimide, ~ containing graphite powder and ~ ll e, said . . having both low wear and friction 25 p- ru~ - and a low coefficient of thermal expansion. However, it is still desirous to continue to develop other and better polyimide ~
having both lowwear and friction p~ r(.. . - < and a low foefficient of thermal expansion.
In the present invention, it was found that a polyimide 30 ~ - contai~ing natural graphite povider, a10ng with carbon or graphite fiber filler, exhibits greatly reduced thermal expansion compared to the same ~ containing no fiber filler. The I also was found to exhibit low wear and friction ~,~lru. against a steel mating surface, superior to the same < u- - ~ containing no fibrous carbon or 35 gr~phi~filler l~contr,s~ fi~olyim~de~ o~hcabove-WO 95/20005 ~ r~ ~ S
referenced U.S. patent ~ ;- - are taught to be, with respect to wear and friction p r ~ against a steel mating surface, only equivalent to the same ~ without ~.. " "
SUIVIMARY OF THE INVF.l~llON
S The present invention provides a polyimide ~. . ~I.. .- :~;- - .
comprised of f - -~' ' quantities of (a) about 8-69 parts by weight of at least one polyimide, (b) about 30-80 parts by weight of natural graphite powder, and (c) about 1-12 parts by weight of carbon or graphite fibrous filler.
DETAlT,T~.n DE~:KII- I ION O~ l~TT''. INVF.~TION
The ~ of the present invention contain about 8-69 parts by weight of at lear.t one polyimide and preferably about 3~56 parts by weight. Parts by weight, as used herein, are indicated as parts per 100 parts of the total weight of the polyimide, the natural graphite powder, and the carbon or graphite fibrous filler. A wide variety of pfJI~ ' ' ' can be used, including those described in Edwards, U.S. Patent 3,179,614, hereby ihl"f~ ulut~ d by reference. The pf,l~ ' '' described therein are prepared from at least one diamine and at least one anhydride. Preferred diamines which can be used include m, ' ~ h .lf, diamine (MPD), p, ' ,' diamine (PPD), UA~I-' "' ~ (ODA), methylene dianiline (MDA) and toluene diamine (TDA). Preferred ~ cs which can be used include . ' - t. l,~.,~.l,, ,"- ~" ' ,.l,id~ (BTDA), biphenyl " ' ~ c (BPDA), trimellitic anhydride (TMA), ~" ., " ' ' - ~ " ~ I,;dc (PMDA), maleic anhydride (MA) and nadic anhydride (NA).
25 ' Preferred pfJI~' ' ' which can be used in the present invention include those prepared from the following, ' ' of anhydride and diamine: BTDA-MPD, MA-MDA, BTDA-TDA-MDA, BTDA-MDA-NA, TMA-MPD & TMA-ODA, BPDA-ODA & BPDA-PPD, BTDA-4,4'-~-' ' ' ,' ~,andBTDA-bis(p- ' r~ ~)-p,p'-biphenyl. An especially s.,li ~L~ tuly polyimide useful in the present invention is that prepared from 1".~' ~""'~ ~" 'l~,dli~C and 4,4'-UA;.-' "' The polyimide . ' ' of the present invention also contain about 30-80 parts by weight of natural graphite powder. Less than about 30 parts by weight of the natural graphite powder could ~ '~ dimirlish the frictional properties required for bushing and bearing _. r Gre~er than about 80 parts byweight of the natllral graphite powder ma ~ WO9512000~; ~,IILJ.. _~ Izi result in a d~ ;aliull of the structural integrity of the final product and loss of the . ~ rn~.c,~ni~ l properties for which p~l~ ' are noted. Preferably, the natural graphite powder comprises about 40-70 parts by weight.
The graphite powde~ used in the . . of the present invention is naturally-occurring. Natural graphite powder, in ~
with carbon or graphite flber in the specifed provides reduced wear and friction. For contrast, when all .., ' '~ produced graphites are used in ' with carbon or graphitc fiber in a 10 polyimide ~ ;- the wear and friction properties of the ~ ';v are increased A central feature of the . , - of the present invention is the i... u-pv-..liu.. of about 1-12 parts by weight of chopped or milled carbon fiber or graphite fiber. As little as 1 part by weight of the carbon or graphite15 fiber ill~lr ~ into the polyimide ~ r '- will ~i~, '' 1,~ reduce the coefficient of linear thermal expansion of the, as compared to a . ' '- graphite powder/polyimide . In addition, the containing graphite powder along with the carbon or graphite fiber, when tested agair;st a steel mating surface, shows wear and friction 20 p~ ' - superior to a . ' ' - graphite powder/polyimide c~ - - '1"`- ';'"1, even at high PV (pressure x velocity) . " Greater than 12 parts by weight of the carbon or graphite fiber can cause variable friction behavior and can depreciate the overall - ' ' properties of parts made from these . Preferably, about 4-10 parts by weight carbon or 25 graphite fiber is used herein.
The present, . can further contain up to about 10 parts by weight of other additives, fillers and dry lubricants which do not depreciate the overall ps ' ~ of the finished polyimide parts, as will be evident to those skilled in the art. Typical of such additional 30 additives are tungsten disulfide and 'l~L '- disulfide.
In the ~.~, of the present; . the order of additional of: . is not critical. The three basic , (iG, the polyimide, the natural graphite powder, and the carbon or graphite fiber) can be blended using . ' milling i: ' , in the required 35 quantities. In the alt~ , some ~ lly available p~
contain ~ d graphite, to which additional graphite can be added by `` -' +~''? `; } t~
W0 95/20û05 2 ~ 7 q 4 8 7 "o..~ I blending t~ ' . if desired. The natural graphite pDwdcr and carbon or graphite fiber can also be cu.... ~ pu~dt~ d into the polyimide, as an alternative to milling; ~ t ' ~ , by blending into a polymer solution of polyimide precursors prior to ~-~ , as the S polyimide. This lattermost ~ ,c.laliu., technique is preferred.
The polyimide . of the present irlvention, when processed into parts, are suitable for providing wear surfaces in the for~n of bushings and bearings where close clearances to adjacent metal surfaces are needed. These bearings include a multitude of small motûr bearings. Parts formed from the present ~- --- r ' ' ' exhibit a reduced coefficient o~ linear thermal expansion by as much as 25% compared to a . ` ~ n graphite powder/polyimide, , In addition, the ~ . when tested against a steel mating surface, shows wear and friction l ~ superior to a r~ ' ' - graphite powder/polyimide :r ~- 1, even at high PV
(pressure x velocity); The reduction of expansion coefficient exhibited by the . , - of the present invention, whOe improving the wear and friction ~ t~ , appears to be unique in the graphite or carbon fiber/natural graphite powder/polyimide - . of the present invention. Other fibrous fillers, when ~u. ' into the relatively hard graphite powder/polyimide . )n, also lower thermal exparlsion by equivalent amounts, but ohen they are abrasive in nature, causing high friction and excessive wear to the polyimide . and to the steel mating surface. It is surprising, therefore, that the carborl fiber performs well when used in the range within the scope of this invention.
BX~MPJ ~
In each of the examples below, polyimide resins were prepared from pyromellitic ~" ~d-idc and 4,4'-oxydianiline, according to the uCC~h.~ of U.S. Patent 3,179,614 or U.S. Patent 4,622,384. The indicated quantity of graphite powder was uul at~ into the polymer solution prior to u. ~ ;u ~ as the polyimide. S ' , '~" carbon fiber (Toray MLD 300, average length, 130 um, diameter, 7 um) was added to the graphite-filled resin by dry blending. The carbûn fiber may also be added to the polymer solution prior to p-~ , as the polyi~nide. The flber was added to the resin as S weight percent, 10 weight percent, etc., so that the final was less than the added amount. For example, 5 grams of fiber added to 100 grams of a resin ~ ;n- containing 60 weight . .
217~
~ WO 95t2000~ , . 4 8 7 A .~ f :
percent graphite yielded a fiAal product of ~ , ~ 38,1% polyimide, 57.1% graphite, and 4.8% carbon fiber.
The resulting filled polyimide resin powder was converted into test specimens by direct forming at a pressure of 100,000 psi (689 MPa) at 5 room ~ , The resulting parts were sintered for three hours at 400 degrees C under nitrogen at ~ pressure. After cooling to room ~ , the parts were machined to ffnal ' for test r, - The 0.25" (6.35 mm) wide contact surhce of the wear/friction test block was machined to such a curvature that it ~ to the outer 10 ~ of the 1.375~ (34.9 mm) diameter x 0.375r (g.5 mm) viide metal mating ring. The blocks were oven dried and d dry over dessicant until tested.
Wear tests were performed using a ~alex No. 1 Ring and Block Wear and Friction Tester. The .~, , is described in ASTM Test 15 mothod D2714. The polyimide block was mounted against tbe rotating metal ring and loaded against it with the selected test pressure. Rotational velocity of the ring was set at tbe desired speed. No lubricant was used between the mating surfaccs. The rings were SAE 4620 steel, Rc 58-63, 6-12 RMS. A new ring was used for each test. Test time was usually 24 hours, 20 except when friction and wear were high, in which case the test was ~ early.
The coefficient of linear thermal expansion was ~ ~ d by a ~ ' analyzer (ASTM E831). On each specimen it was measured in the direction ~ - ' to the direction of forming pressure 25 when the part was made.
Examples I to 6 and CQmv~r~tive~i xLmvLes A tQ .T (T~ble 1) Wear test results for these examples are at 256 psi (1.77 MPa) pressure and 390 fpm (1.98 m/s) velocity for a PV of ~ P~ 100,000 psi-fpm (3.5 MPa-m/s). Examples 1-5 show the effect of adding carbon fiber 30 on the wear, friction, and coefficient of linear thermal expansion (Cl[E) of a natural graphite-filled polyimide. Specifically, Example 1 and 2 are fromtheadditionof5and 10weightpercent,I~o~
carbon fiber to the ~ , of C: . ~. Example A. All three properties were improved r `~y. Example 3 shows that further 35 illl~l u . . results from an even higher natural graphite content.
Examples 4 and 5 show simDar . u . over the parent i , in WO 9S/2000~ ? S - 6 _ 2 1 7 9 4 8 7 JalaliVC Example B at lower natural graphite content. Example 6 A.. ~: .t~ nt. 5 good results using a natural graphite from a second source.
The addition of carbon fiber to a synthetic graphite in the polyimide ~ . in (' , ~_ Example C similarly improved the 5 CIE, but resulted in very high wear and friction compared with its parent "' ' `I'q~ al a~ Example D. Synthetic graphite from a second source, C~ Jala~ Example E, gave excellent wear and friction results, but these were degraded i" '~ 'y with the addition of carbon f~ber in C~ Jala~i~., Example F.
C . ~i _ Examples G through J show that the addition of higher ~ C~ .-t~ of c&rbon fiber can result in eithervariable friction or very high friction with reduced wear resistance, even when the graphite is natural grade.
W095~20005 ~ '; ``, 2 1 79487 ~ u . ,~
8 ~ æ O o O _ ~ o ~ ~ A A A A o ;:- o C o o O O O O o O
o ~ c~ o ~ ~ ~ 3 o ,~ ~ X X X - ~ ~ o ~ ~ '~ ~ ~ C
D ~ -- O O -- O O -- ~ O O
ll 11 ll 11 z _ C'~ ~ U Cl ~I~ ~ O ~
.
W0 95/20005 ` ` 2 1 7 9 4 8 7~
Exsmale 7 snd ComDsratiYe Examples K snd L (T ' - 2) Wear test conditions for the tests in Table 2 are the same as for Table 1 (PV = 100,000 psi-fpm). For Example 7 and CO~ a~
Examples K and L, a chopped graphite fiber (Kureha grade 2007S, 5 ~lu d~at~,lj 200 um average length and 20 um diameter) was used in place of the carbor~ fber. Example 7 shows that the CTE can be reduced and good wear and friction test results ~ ' - d when thc graphite flber is combined with natural graphite. ~ . ._ Example K shows that in with synthetic graphite, the graphite fiber gives very high 10 friction. Ccl...y~.-d~ Example L shows that at a higher ~ ~liun of graphite fiber, poor wear and friction results, even when the graphite is the natural grade.
.
wo gs~ooos ; . . 2 1 7 9 4 8 7 ~, ~ 8 ~ _ ~
8 ~ ~ _ A A
~0 .~ C~` O ~
Z ~ 4 ~-1 W095120005 ~ ; 2179487P I/u ,~
,10- ' ExamDles 8 and 9 and Coml~arat~ve EY~mples M nnd N ~able 3) Wear and friction test results for the examples in Table 3 are at 192 psi (1.32 MPa) pressure and 134 fpm (0.68 m/s) for a PV of U,.i~ .t~ 25,000 psi-fpm (0.9 MPa-m/s). Examples 8 and 9 show that 5even at a lower PV, friction F e r ~ iS improved compared with the parent ~u ~ -- in ~ Example M. Wear and friction are both superior compared with C . ._ Example N, in which carbon fiber is combined with synthetic graphite.
.. .
WO95/20005 ~ 79487 ~" 5 ,~
~_I o ~ ~ _ _ _ ~ ~o ~ O O o o t .13 o w o r~
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Claims (7)
1. A polyimide composition comprised of complemental quantities of (a) about 8-69 parts by weight of at least one polyimide, (b) about 30-80 parts by weight of natural graphite powder, (c) and about 1-12 parts by weight of carbon or graphite fiber, wherein the parts by weight given above are based upon the total weight of components (a), (b), and (c) only.
2. The polyimide composition of Claim 1 wherein the polyimide is a single polyimide.
3. The polyimide composition of Claim 1 wherein the polyimide is prepared from pyromellitic dianhydride and 4,4'-oxydianiline.
4. The polyimide composition of Claim 1 further containing up to about 10 weight percent of other additives.
5. The polyimide composition of Claim 1 wherein the parts by weight of the component (b) ranges from 40-70.
6. The polyimide composition of Claim 1 wherein the parts by weight of the component (c) range from 4-10.
7. The polyimide composition of Claim 1 comprised of about 30-56 parts by weight of the component (a), about 40-70 parts by weight of the component (b), and about 4-10 parts by weight of the component (c).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US18471094A | 1994-01-21 | 1994-01-21 | |
| US08/184,710 | 1994-01-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2179487A1 true CA2179487A1 (en) | 1995-07-27 |
Family
ID=22678030
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2179487 Abandoned CA2179487A1 (en) | 1994-01-21 | 1995-01-19 | Polyimide composition having improved properties |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH09508161A (en) |
| CA (1) | CA2179487A1 (en) |
| WO (1) | WO1995020005A1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11279543A (en) * | 1998-03-25 | 1999-10-12 | Sanyo Electric Co Ltd | Thermally conductive organic material |
| JP2008545839A (en) * | 2005-05-27 | 2008-12-18 | イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー | Resin composition having low coefficient of thermal expansion and article made therefrom |
| US7858687B2 (en) * | 2008-07-30 | 2010-12-28 | E.I. Du Pont De Nemours And Company | Polyimide resins for high temperature wear applications |
| WO2010025339A1 (en) * | 2008-08-29 | 2010-03-04 | E. I. Du Pont De Nemours And Company | Composite parts for airplane engines |
| JP5701893B2 (en) * | 2009-10-27 | 2015-04-15 | イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニーＥ．Ｉ．Ｄｕ Ｐｏｎｔ Ｄｅ Ｎｅｍｏｕｒｓ Ａｎｄ Ｃｏｍｐａｎｙ | Polyimide resin for high temperature wear applications |
| EP2493967A1 (en) * | 2009-10-27 | 2012-09-05 | E. I. du Pont de Nemours and Company | Compositions and articles for high-temperature wear use |
| US20110098409A1 (en) * | 2009-10-27 | 2011-04-28 | E.I. Du Pont De Nemours And Company | Compositions and articles for high-temperature wear use |
| DE102013221968A1 (en) * | 2013-10-29 | 2015-04-30 | Vitrulan Technical Textiles Gmbh | Heating medium and electrically conductive radiator |
| EP3192827B1 (en) * | 2014-09-12 | 2024-03-06 | Toyo Seikan Group Holdings, Ltd. | Fiber-reinforced polyimide resin molded article and method for producing same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4395514A (en) * | 1980-04-18 | 1983-07-26 | Celanese Corporation | Process for preparing a carbon fiber reinforced composite article which utilizes a polyimide matrix |
| US4360626A (en) * | 1981-04-24 | 1982-11-23 | E. I. Du Pont De Nemours And Company | Oxidatively stable polyimide compositions |
-
1995
- 1995-01-19 JP JP7519591A patent/JPH09508161A/en active Pending
- 1995-01-19 CA CA 2179487 patent/CA2179487A1/en not_active Abandoned
- 1995-01-19 WO PCT/US1995/000378 patent/WO1995020005A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995020005A1 (en) | 1995-07-27 |
| JPH09508161A (en) | 1997-08-19 |
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