U.S. patent application number 10/292289 was filed with the patent office on 2003-07-03 for highly chemically resistant thermoplastic vulcanizates based on fluorocarbon polymers and seal-gasket products made with same.
Invention is credited to Chmielewski, Craig A..
Application Number | 20030125466 10/292289 |
Document ID | / |
Family ID | 24389864 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030125466 |
Kind Code |
A1 |
Chmielewski, Craig A. |
July 3, 2003 |
Highly chemically resistant thermoplastic vulcanizates based on
fluorocarbon polymers and seal-gasket products made with same
Abstract
Disclosed are new fluid resistant, in particular resistant to
chemically basic compounds, and exceptional processing fluorine
containing thermoplastic vulcanizate compositions comprising a
continuous phase of at least one melt-formable thermoplastic
fluorocarbon resin and a disperse phase consisting of a blend of at
least two vulcanizable fluorine containing elastomers with at least
one of the fluoroelastomers being a terpolymer of vinylidene
fluoride/tetrafluoroethylene/propylene. The vinylidene
fluoride/tetrafluoroethylene/propylene fluoroelastomer comprises
between 5 and 95 weight percent of the total dispersed elastomer
phase, which the total disperse elastomer phase comprises from
between 40 and 90 weight percent based on the total amount of the
continuous phase and the disperse phase combined.
Inventors: |
Chmielewski, Craig A.;
(Wixom, MI) |
Correspondence
Address: |
Dinnin & Dunn P.C.
Suite 500
2701 Cambridge Ct.
Auburn Hills
MI
48326
US
|
Family ID: |
24389864 |
Appl. No.: |
10/292289 |
Filed: |
November 12, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10292289 |
Nov 12, 2002 |
|
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09597050 |
Jun 20, 2000 |
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Current U.S.
Class: |
525/199 ;
525/200 |
Current CPC
Class: |
C08L 27/18 20130101;
C08L 27/12 20130101; C08L 2666/04 20130101; C08L 2666/04 20130101;
C08L 2666/04 20130101; C08L 27/12 20130101; C08L 2205/02 20130101;
C08L 27/18 20130101; C08L 27/16 20130101; C08L 2205/03 20130101;
C08L 27/16 20130101 |
Class at
Publication: |
525/199 ;
525/200 |
International
Class: |
C08L 027/12 |
Claims
What is claimed:
1. A fluorine containing thermoplastic vulcanizate composition
comprising a continuous phase of at least one uncured melt formable
thermoplastic resin and a blend of at least two cured fluorine
containing elastomers forming a dispersed elastomer phase where one
of the elastomers is a vinylidene
fluoride/tetrafluoroethylene/propylene terpolymer; wherein the
vinylidene fluoride/tetrafluoroethylene/propylene terpolymer
comprises between 5 and 95 weight percent of the total dispersed
elastomer phase, and the total dispersed elastomer phase comprises
from between 40 and 90 weight percent based on the total amount of
the continuous phase and the disperse phase combined.
2. The composition of claim 1 wherein the thermoplastic
fluorocarbon resin has a fluorine content of at least 35 weight
percent.
3. The composition of claim 1 wherein the vinylidene
fluoride/tetrafluorethylene/propylene terpolymer comprises between
about 23 and about 75 weight percent of the total dispersed
elastomer phase.
4. The composition of claim 1 wherein the total dispersed elastomer
phase comprises between about 56 and about 67 weight percent of the
total amount of the continuous phase and the disperse phase
combined.
5. The composition of claim 1 wherein the thermoplastic resin is a
terpolymer of tetrafluoroethylene/vinylidene
fluoride/hexafluoropropylene- .
6. The composition of claim 1 wherein the thermoplastic resin is a
copolymer of tetrafluoroethylene/ethylene.
7. The composition of claim 1 wherein the thermoplastic resin is a
copolymer of tetrafluorethylene/hexafluoropropylene.
8. An article formed from the composition of claim 1.
9. An article formed from the composition of claim 5.
10. An article formed from the composition of claim 6.
11. An article formed from the composition of claim 7.
12. A process for producing a fluorine containing thermoplastic
vulcanizate composition comprising the steps of: melt blending at
least one uncured melt formable thermoplastic fluorocarbon resin
with a blend of fluorine containing elastomers, where at least one
of the elastomeric components is a vinylidene
fluoride/tetrafluoroethylene/propylene terpolymer, and where the
elastomers and thermoplastic is melt blended at a temperature
higher than the melting temperature of the thermoplastic; and
vulcanizing the fluorine containing elastomers while maintaining
the shear mixing forces on the blend thereby forming a dual phase
composition comprising a cured dispersed particle phase of the
fluorine containing elastomers suspended in an uncured melt
formable continuous phase of the fluorocarbon resin.
13. The process according to claim 12 wherein at least one member
selected from the group consisting of vulcanizing agents and
vulcanization accelerators is added after the melt blending step
and before the vulcanizing step.
14. A product formed according to the process of claim 12.
15. The process of claim 12 further comprising the step of forcing
the composition through an extrusion die.
16. The process of claim 12 further comprising the step of
injecting the composition into a mold cavity.
17. A product formed according to a process comprising the steps
of: melt blending at least one uncured melt formable thermoplastic
fluorocarbon resin and a blend of fluorine containing elastomers,
where at least one of the components of the blend of elastomers is
a vinylidene fluoride/tetrafluoroethylene/propylene terpolymer, and
where the blend of elastomers and thermoplastic is melt blended at
a temperature higher than the melting temperature of the
thermoplastic; and partitioning the mixture into a dual phase
composition by vulcanizing the fluorine containing elastomers while
maintaining shear mixing forces, thereby forming an uncured
continuous phase of the thermoplastic fluorocarbon resin and a
cured dispersed phase of the fluorine containing elastomers.
18. The product of claim 17 wherein the thermoplastic resin is a
terpolymer of tetrafluoroethylene/vinylidene
fluoride/hexafluoropropylene- .
19. The product of claim 17 wherein the thermoplastic resin is a
copolymer of tetrafluoroethylene/ethylene.
20. The product of claim 17 wherein the thermoplastic resin is a
copolymer of tetrafluoroethylene/hexafluoropropylene.
21. The product of claim 17 wherein the thermoplastic resin is a
copolymer of tetrafluoroethylene/perfluoropropylvinyl ether.
22. The product of claim 17 wherein the thermoplastic resin is a
copolymer of trifluoroethylene chloride/ethylene.
23. The product of claim 17 wherein the thermoplastic resin is a
vinylidene fluoride polymer.
24. The product of claim 17 wherein the process further comprises
the step of extruding the product.
25. The product of claim 17 wherein the process further comprises
the step of injection molding the product.
26. A fluorine containing thermoplastic vulcanizate composition
comprising a continuous phase of at least one uncured melt formable
thermoplastic resin and a blend of at least two cured fluorine
containing elastomers forming a dispersed elastomer phase where one
of the elastomers is a vinylidene
fluoride/tetrafluoroethylene/propylene terpolymer; wherein the
vinylidene fluoride/tetrafluoroethylene/propylene terpolymer
comprises between about 23 and about 75 weight percent of the total
dispersed elastomer phase, and the total dispersed elastomer phase
comprises from between about 56 and about 67 weight percent based
on the total amount of the continuous phase and the disperse phase
combined.
Description
[0001] This Application is a Divisional of U.S. patent application
Ser. No. 09/597,050, and Claims the Benefit of Applicant's Earlier
Provisional Application No. 60/168,414 Filed Dec. 1, 1999.
TECHNICAL FIELD
[0002] The present invention relates to fluorine containing
thermoplastic vulcanizate ("TPV") compositions comprising a
continuous thermoplastic fluorocarbon resin phase and a dispersed
amorphous vulcanized fluorine containing elastomer phase, which is
useful as a melt formable material having rubber elasticity.
Further it relates to a process for producing a fluorine containing
thermoplastic vulcanizate composition, which comprises melt
blending the above mentioned thermoplastic fluorocarbon resin and
the non-vulcanized amorphous fluorine containing elastomer,
followed by dynamically vulcanizing this blend to form chemically
cross-linked elastomer particles dispersed in the thermoplastic
fluorocarbon resin.
[0003] The compositions of this invention have the highly desirable
property of low compression set, that is when articles made of the
composition are compressed for long periods of time, even at high
temperatures, they have a strong tendency to return to their
original size and shape. Another advantage is that articles made
from the composition of this invention are highly fluid resistant,
even to fluids containing chemically basic components. Articles
molded from the composition of the present invention can find use
as seals and gaskets in applications where high temperatures and
harsh chemical environments are common, for example in certain
types of automotive or aerospace applications.
BACKGROUND OF THE INVENTION
[0004] A two phase composition comprising a continuous phase
thermoplastic material and a disperse phase elastomer, produced by
dynamically vulcanizing the elastomer while the discrete phase
elastomer is dispersed in the continuous phase thermoplastic
material, is known, for example, in Coran et al. U.S. Pat. Nos.
4,348,502, 4,130,535, 4,173,556, 4,207,404 and 4,409,365.
[0005] Fluorocarbon resins and fluorine containing elastomers are
excellent in heat resistance, and a two phase blend obtainable by a
combination of these materials, is considered to be excellent in
heat resistance as well. Such a fluorine containing two phase blend
is discussed by Pazos and Rees in EP patent 168020. The elastomer
used is substantially a vinylidene fluoride/hexafluoropropylene
elastomer, and as its vulcanization method, polyol vulcanization by
a combination of bisphenol AF, an acid receiving agent and an onium
salt, or peroxide vulcanization by a combination of an organic
peroxide and a polyfunctional unsaturated compound, is
employed.
[0006] The compounds disclosed in EP 168020 require oven
vulcanization (post cure) following dynamic vulcanization. By only
dynamically vulcanizing the materials the mechanical properties
tend to be inadequate, particularly the permanent strain. In
addition, following dynamic vulcanization, the compositions also
tend to powder, rendering them extremely difficult to subsequently
melt process in standard thermoplastic processing equipment.
Finally, the compounds of EP 168020A are inherently susceptible to
chemical attack and degradation by chemically basic moieties.
[0007] To address some of these problems, Kamiya and Saito in U.S.
Pat. No. 5,354,811 describe alternate two phase dynamically
vulcanized compounds based on fluorocarbon resin continuous phase
and a dispersed fluorocarbon elastomer dispersed phase. The
fluorine containing elastomers of U.S. Pat. No. 5,354,811 have
vulcanizable sites selected from the group consisting of epoxy
groups, carboxylic acid groups, carboxylic acid derivative groups,
sulfonic acid groups and sulfonic acid derivative groups. These
chemically functional cure sites allow vulcanization to proceed
quickly and fully in a short period of time. Such materials were
shown to have adequate properties without the need of a post
cure.
SUMMARY OF THE INVENTION
[0008] A major advantage of the present invention is that it
operates to compose and produce fluorocarbon based TPV's which
solve problems such as TPV powdering upon synthesis, poor melt
processing, and poor physical and mechanical properties, without
subjection to a post cure processing cycle. Furthermore, it is the
intent of the present invention to overcome these problems without
resorting to chemically modifying standard commercial
fluoroelastomers, or producing fluoroelastomers from their monomer
constituents, with special cure site monomers. This invention
provides a two phase composition comprised of fluorinated polymers,
that is useful as a thermoplastic vulcanizate which is excellent in
mechanical properties, excellent in heat resistance, excellent in
fluids resistance, including fluids containing basic moieties, and
easily melt processible. In addition, a process for its production
is disclosed.
[0009] It has been found that the desired two phase composition can
be obtained by using as the fluoroelastomer component a blend of
two or more fluoroelastomers with at least one of the
fluoroelastomers being a terpolymer of vinylidene
fluoride/tetrafluoroethylene/propylene. The present invention has
been accomplished based on this discovery.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0010] The present invention provides a fluorine containing
thermoplastic vulcanizate composition comprising a continuous phase
of at least one melt formable thermoplastic fluorocarbon resin and
a dispersed vulcanized elastomer phase containing a blend of two or
more fluoroelastomers with at least one of the fluoroelastomers
being a terpolymer of vinylidene
fluoride/tetrafluoroethylene/propylene. The vinylidene
fluoride/tetrafluoroethylene/propylene fluoroelastomer comprises
between 5 and 95 weight percent of the total dispersed elastomer
phase, while the total dispersed elastomer phase comprises from
between 40 and 90 weight percent based on the total amount of the
continuous phase and the disperse phase combined.
[0011] Further, the present invention provides a process for
producing a fluorine containing thermoplastic vulcanizate
composition, which comprises a step of melt blending at least one
melt formable thermoplastic fluorocarbon resin and at least one
fluorine containing elastomer with at least one of the
fluoroelastomers being a terpolymer of vinylidene
fluoride/tetrafluoroethylene/propylene while exerting a mixing
shear force at a temperature higher than the melting point of the
thermoplastic fluorocarbon resins.
[0012] The present invention is now further described in detail
with reference to the preferred embodiments and the best mode.
[0013] The thermoplastic fluorocarbon resin useful for the present
invention is required to have thermoplasticity, i.e., it is
required to be melt formable. Namely, it must be a resin whereby
the melt flow or the volume flow rate described in ASTM D-1238, or
ASTM D-2116, can be measured at a temperature higher than the
melting point. It is preferably a thermoplastic fluorocarbon resin
which can be melt formed at a temperature at which there is no
problem of deterioration of the fluorine containing elastomer.
Among thermoplastic fluorocarbon resins, all fluorocarbon resins
except for polytetrafluoroethylene resins which cannot be melt
formed, may be employed.
[0014] The thermoplastic fluorocarbon resin useful for the present
invention is a thermoplastic fluorocarbon resin having a fluorine
content of at least 35% by weight, which can be obtained by
polymerizing an ethylenically unsaturated compound containing a
completely or partially fluorinated fluoroolefin, preferably at
least one fluoroolefin selected from the group consisting of
tetrafluoroethylene, hexafluoropropylene, trifluoroethylene,
vinylidene fluoride, vinyl fluoride, trifluoroethylene chloride and
a perfluoroalkylvinyl ether (wherein the alkyl group has from 1 to
8 carbon atoms).
[0015] The ethylenically unsaturated compound may, for example, be
a non-fluorinated olefin such as ethylene or propylene, an
alkylvinyl ether, or a perfluoroalkyl ethylene, in addition to the
above olefins.
[0016] Preferred among such polymers is a
tetrafluoroethylene/hexafluoropr- opylene/vinylidene fluoride
terpolymer, a tetrafluoroethylene/ethylene copolymer, a
tetrafluoroethylene/hexafluoropropylene copolymer, a
tetrafluoroethylene/perfluoropropylvinyl ether copolymer, a
trifluoroethylene chloride/ethylene copolymer, or a vinylidene
fluoride polymer. Particularly preferred are a
tetrafluoroethylene/hexafluoropropy- lene/vinylidene fluoride
terpolymer and a tetrafluoroethylene/ethylene copolymer. Most
preferred is a tetrafluoroethylene/hexafluoropropylene/vi- nylidene
fluoride terpolymer. A plurality of fluorocarbon resins may be used
in combination. These copolymers may have other copolymerizable
components further copolymerized.
[0017] Suitable semi-crystalline fluorine containing thermoplastics
are tetrafluoroethylene/hexafluoropropylene/vinylidene fluoride
terpolymers which are available under the tradename THV from Dyneon
LLC (Oakdale, Minn.), such as grades THV 410, THV 500 and THV 610X,
especially the latter. The monomer ratio affects crystallinity,
mechanical properties and melt temperature. These grades have
fluorine contents in the range of 70 to 76 weight percent and have
crystalline melting points of 155.degree. C., 165.degree. C. and
185.degree. C. respectively. As an example of the monomer ratios in
these terpolymers, THV410 has as a ratio of
tetrafluoroethylene/hexafluoropropylene/vinylidene fluoride of
53/18/29 respectively. Generally, an increase in the
tetrafluoroethylene in the monomer mix leads to an increase in the
crystalline melting point.
[0018] The fluorocarbon resin is suitably selected also for the
combination with the fluorine containing elastomer which will be
described hereinafter. For example, when the fluorocarbon resin for
the fluorine containing elastomer is a polymer having vinylidene
fluoride units, a polarity will be formed. Accordingly, as a
combination of the fluorocarbon resin and the fluorine containing
elastomer, it is most desirable to select a combination of the
resin and the elastomer both having vinylidene fluoride units to
obtain a composition having uniform and excellent physical
properties.
[0019] The fluorocarbon elastomers required for the present
invention are blends of two or more fluorine containing elastomers
where at least one of the elastomers is vinylidene
fluoride/tetrafluoroethylene/propylene terpolymer. Small amounts of
a fourth monomer, such as hexafluoropropylene, may or may not be
present. The proportion of the respective monomer units in such
terpolymers are optionally selected, taking into account various
properties, such as the mechanical properties, heat resistance, low
temperature resistance, chemical resistance, oil resistance, etc.
For instance, the vinylidene fluoride-tetrafluoroethylene-propylene
terpolymer preferably comprises from 2 to 50 mol % of vinylidene
fluoride units, from 20 to 60 mol % tetrafluoroethylene units and
from 20 to 50 mol % of propylene units.
[0020] Further, in such terpolymers, the proportions of the
vinylidene units is preferably from 2 to 50 mol %, more preferably
from 10 to 40 mol %. If the proportion is too high, there will be
drawbacks with respect to the physical properties, such as a
decrease in the alkali resistance or in the amine resistance of the
terpolymer. On the other hand, if the proportion is too low, the
formation of unsaturated bonds will be inadequate, and the
effectiveness for the improvement of the curability
deteriorates.
[0021] Suitable amorphous vinylidene
fluoride/tetrafluoroethylene/propylen- e terpolymers are available
under the tradename BRE (Base Resistant Elastomer) from Dyneon LLC
(Oakdale, Minn.), such as grades BRE 7131X, BRE 7132X and BRE
7231X, especially the first one listed. The fluorine content of
these terpolymer elastomers is approximately 60 weight percent.
Appropriate monomer ratios and the absence, or near absence, of
hexafluoropropylene, renders the vinylidene
fluoride/tetrafluoroethylene/- propylene terpolymers chemically
resistant to chemically basic moieties.
[0022] The vinylidene fluoride/tetrafluoroethylene/propylene
fluoroelastomer comprises between 5 and 95 weight percent of the
total dispersed elastomer phase, while the total disperse elastomer
phase comprises from between 40 and 90 weight percent based on the
total amount of the continuous phase and the disperse phase
combined in the material of this invention.
[0023] The elastomeric components making up the balance of the
dispersed phase are fluorine containing amorphous materials which
are known in the art and are commercially available. Suitable
elastomeric components include, but are not limited to, copolymers
of vinylidene fluoride/hexafluoropropylene, copolymers of
tetrafluoroethylene/propylene- , copolymers of
tetrafluoroethylene/perfluoroalkylvinyl ether, copolymers of
vinylidene fluoride/perfluoroalkylvinyl ether, terpolymers of
tetrafluoroethylene/vinylidene fluoride/hexafluoropropylene and
terpolymers of tetrafluoroethylene/perfluoroalkylvinyl
ether/propylene.
[0024] The elastomer phase of the composition of this invention may
be cured with conventional curing systems known for curing
fluoroelastomers, such as combinations of magnesium oxide/Bisphenol
AF/organophosphonium salts, magnesium oxide/the dipotassium salt of
Bisphenol AF/dicyclohexyl 18 Crown
6,2,5-dimethyl-2,5-diterbutylperoxyhexyne-3/meta
phenylenebismaleimide or triallyl isocyanurate and cumene
hydroperoxide/maleimide or triallyl isocyanurate.
[0025] The composition of the present invention may contain
vulcanization accelerators, fillers, antioxidants, stabilizers,
pigments, processing assistants, etc. in an amount at a level of
common use.
[0026] The particle size of the dispersed phase of the present
invention varies depending upon the components of the composition,
the proportions of the respective components, the viscosities of
the respective components, the production conditions, etc. However,
the average particle size is: broadly stated, no larger than about
50 microns, preferably no larger than about 5 microns, and most
preferably not larger than 3 microns.
The Process
[0027] The process of the present invention comprises melt blending
the thermoplastic fluorocarbon resin and the fluorine containing
elastomers at a temperature higher than the melting temperature of
the fluorocarbon resin in either batch or continuous mixers,
followed by vulcanizing the fluorine containing elastomer while
exerting a mixing shear force. The temperature for mixing may be
suitably selected depending on the types of thermoplastic
fluorocarbon resin and the fluorine containing elastomer used.
[0028] It is critical to conduct the vulcanization while exerting a
mixing shear force. As the vulcanization is conducted while a
mixing shear force is applied, the thermoplastic fluorocarbon resin
will form a continuous phase; and a disperse phase, composed of a
cured fluorocarbon elastomer, will be uniformly dispersed in the
continuous phase. Such a continuous phase will form even when the
thermoplastic resin is not the major component. If the continuous
and the disperse phase are reversed, that is if the thermoplastic
fluorocarbon resin becomes the dispersed phase and the fluorocarbon
elastomer and continuous phase, then the material is not melt
processible.
[0029] The present invention provides a two phase composition
comprising a continuous phase thermoplastic material and a disperse
phase elastomer, produced by dynamically vulcanizing the
elastomer--that is curing the elastomer while it is undergoing
shear stress from mixing and after it has been melt mixed with the
thermoplastic. A fluorocarbon resin is used as the thermoplastic
phase and a blend of two or more fluorine containing elastomers are
used as the dispersed elastomeric phase, where at least one of the
elastomers is a fluorine vinylidene fluoride/tetrafluoroethyle-
ne/propylene terpolymer. The present invention is highly useful as
a thermoplastic vulcanizate, excellent in moldability, mechanical
properties and fluid resistance, especially to fluids containing
chemically basic moieties. The present invention also provides a
process for its production.
[0030] The following examples explain the present invention,
however, in no way should they be taken to limit the scope of the
present invention.
[0031] All data presented in the following examples were generated
using standard ASTM test methods. The hardness test was performed
according to ASTM D2240-97, the tensile properties according to
ASTM 412-98a and the specific gravity according to ASTM D297-93.
Fluid immersion testing was performed according to ASTM D471-97,
and compression set testing according to ASTM D395--Method B.
[0032] In addition, test plaques used to die cut test specimens
were all prepared by compression molding material for 5 minutes at
254.degree. C. and then cooling under pressure for 10 minutes so
the temperature falls below 100.degree. C.
EXAMPLES 1 & 2
[0033] Compositions of Examples 1 and 2 illustrate the present
invention. The fluoroelastomer FE 5642Q is a copolymer of
vinylidene fluoride/hexafluoropropylene containing 65.9 weight
percent fluorine and the fluoroelastomer BRE 7131X is a terpolymer
of vinylidene fluoride/tetrafluoroethylene/propylene containing 60
weight percent fluorine. Both fluoroelastomers have a proprietary
bisphenol AF type cure system incorporated into materials by the
supplier. THV 610X is a thermoplastic fluorocarbon terpolymer of
tetrafluoroethylene/vinylidene fluoride/hexafluoropropylene having
a crystalline melting point of about 190.degree. C. All three
fluorocarbons are commercial products of Dyneon LLC (Oakdale,
Minn.).
[0034] These compositions were prepared by melt mixing the
fluoroelastomers with the fluorocarbon thermoplastic and black
filler in a Moriyama mixer for approximately 4 minutes at
approximately 220.degree. C. to 235.degree. C. The water and acid
scavengers were then added and mixing continued for 6 minutes while
vulcanization proceeded. The final product was solid at room
temperature and had good thermoplastic consistency. Compositions
and physical properties are shown below in Table 1.
1TABLE EXAMPLES 1 2 wt. % wt. % MATERIAL Fluorel FE 5642Q 36.6 42.7
BRE 7131X 10.9 14.2 THV 610X 36.9 28.5 Austin Black 325 7.9 0.0
Carbon Black N990 0.0 8.5 Ca(OH).sub.2 4.3 4.0 MgO 3.4 2.0 Physical
Properties Hardness Shore A 86 80 UTS Mpa (psi) 827 (1199) 6.74
(977) EB % 266 162 M100 Mpa (psi) 6.32 (917) 5.05 (733) Sp. Grav.
1.84 1.86 Compression Set 28% N/A (70 Hrs. @ 21.degree. C.) Oil Age
- IRM 903 7O Hrs @ 125.degree. C. Hardness Change pts -4 0 UTS
Change % -16 -13 EB Change % -8 -30 M100 % -17 +13 Volume Swell %
+1 +1
EXAMPLE 3 THROUGH 7
[0035] Compositions of Examples 3 through 7 illustrate the effect
of the ratio of two fluoroelastomers on the final TPV material
consistency and physical properties of the present invention (see
Table 2). Example 3 is void of the terpolymer vinylidene
fluoride/tetrafluoroethylene/propylene, and so represents the prior
art. The vinylidene fluoride/hexafluoropropyl- ene copolymer of
these examples is the same as that used in Examples 1 and 2
(Fluorel FE 5642Q), while the terpolymer of vinylidene
fluoride/tetrafluoroethylene/propylene, BRE 7231X, is a variation,
having slightly higher vinylidene fluoride levels, of the
terpolymer used in Examples 1 and 2. E14994 is a non-commercial
thermoplastic fluorocarbon terpolymer of
tetrafluoroethylene/vinylidene fluoride/hexafluoropropylene- ,
having a crystalline melting point of about 210.degree. C. Both the
BRE 7231X and E14994 were supplied by Dyneon LLC (Oakdale,
Minn.).
[0036] Compositions of Examples 3 through 7 were compounded in the
same manner as those of Examples 1 and 2, and show good ultimate
tensile strength and elongation-at-break (see Table 2). Examples 4
through 7 were solid and continuous at room temperature and had
good thermoplastic consistency in the melt state. Example 3,
lacking a vinylidene fluoride/tetrafluoroethylene/propylene
terpolymer, powdered immediately follow the addition of the cure
activator and acid scavenger. A material of the powdery consistency
of that of Example 3 does not flow freely and cannot be easily
processed on standard thermoplastic processing equipment. Such a
result is consistent with the observations made in EP 168020A and
demonstrates an advantage of the present invention over the prior
art.
2TABLE 2 EXAMPLES 3 4 5 6 7 wt. % wt. % wt. % wt. % wt. MATERIAL
Fluorel FE 5642Q 52.0 39.0 26.0 13.0 0.0 BRE 7231X 0.0 13.0 26.0
39.0 52.0 E14994 34.7 34.7 34.7 34.7 34.7 Carbon Black N990 7.8 7.8
7.8 7.8 7.8 Ca(OH).sub.2 3.6 3.6 3.6 3.6 3.6 MgO 1.8 1.8 1.8 1.8
1.8 Total 100.0 100.0 100.0 100.0 100. Physical Properties Hardness
Shore A 87 89 90 90 88 UTS Mpa (psi) 8.84 (1282) 7.33 (1064) 6.77
(982) 5.61 (813) 6.55 (9 EB % 222 235 230 188 159 M100 Mpa (psi)
5.29 (767) 5.31 (770) 5.16 (748) 4.94 (716) 5.19 (7 Sp. Gravity
1.91 1.89 1.87 1.84 1.82
EXAMPLES 8 THROUGH 12
[0037] Examples 8 through 12 illustrate retention of physical
properties of the materials of Examples 3 through 7 after being
soaked for 168 hours at 150.degree. C. in a gear lubricant
solution. The solution contains 94 weight percent Anglamol 6055, an
automatic transmission fluid (ATF) from Lubrizol (Widkliffe, Ohio)
and 6 weight percent Sturaco 7098LO, a high amine containing
friction modifier from the D.A. Stuart Company (Warrenville,
Ill.).
[0038] Table 3 shows excellent retention of physical properties of
the materials of this invention (Examples 9 through 12) in an ATF
containing a high amine content additive package.
[0039] The prior art, represented in Example 8, displays much
poorer retention of ultimate tensile strength than the materials of
the present invention.
3TABLE 3 EXAMPLES Physical Properties 8 9 10 11 12 Hardness Change
pts +2 +1 0 -3 -5 UTS % -22.9 -1.8 +3.2 -3.3 -7.7 EB Change % -62
-68 -60 -32 -25 Volume Change % +4.2 +4.0 +5.3 +7.0 +4.2
EXAMPLE 13 THROUGH 16
[0040] Compositions of Examples 13 through 16 illustrate the effect
on physical properties of varying the fluorothermoplastic loading
while keeping the ratio of the two fluoroelastomers, the vinylidene
fluoride/hexafluoropropylene and the vinylidene
fluoride/tetrafluoroethyl- ene/propylene terpolymer, constant at
1:1. All raw materials of Examples 13 through 16 are the same as
those used in Example 3 through 7.
[0041] Again, compositions of Examples 13 through 16 were
compounded in the same manner as those of Example 1 and 2.
Materials of Examples 13 through 16 show good ultimate tensile
strength and elongation-at-break and were solid at room temperature
and had good thermoplastic consistency. Table 4 shows the material
compositions and physical properties. Accompanying a reduction in
fluoroplastic loading is a reduction in material hardness, as well
as a reduction in tensile strength.
4TABLE 4 EXAMPLES 13 14 15 16 wt. % wt. % wt. % wt. % Fluorel FE
5642Q 26.0 26.0 26.0 26.0 BRE 7231X 26.0 26.0 26.0 26.0 E14994 34.7
30.0 25.5 21.0 Carbon Black N990 7.8 8.4 8.9 9.4 Ca(OH).sub.2 3.6
3.9 4.2 4.4 MgO 1.8 2.0 2.1 2.2 Total 100.0 100.0 100.0 100.0
Physical Properties Hardness Shore A 89 86 84 80 UTS MPa (psi) 7.01
(1017) 6.60 (957) 5.82 (844) 4.57 (663) EB % 181 238 235 232 M100
MPa (psi) 5.35 (776) 4.92 (714) 4.21 (611) 3.32 (482) Sp. Gravity
1.87 1.86 1.84 1.83
EXAMPLES 17 AND 18
[0042] Examples 17 and 18 illustrate the resistance of the
materials of the invention of a model automotive fuel. Materials of
Examples 4 and 15 are given as Examples 17 and 18 respectively and
show good resistance to ASTM Fuel C+10% ethanol at 40.degree. C.
for up to 168 hours.
5TABLE 5 EXAMPLES 17 18 Volume Swell, % 22 15 27 70 20 30 168 20 30
Weight Gain, % 22 6 11 70 8 12 168 8 12
EXAMPLES 19 THROUGH 21
[0043] Examples 9 through 21 further illustrate the resistance of
the materials of the invention which is particularly aggressive to
fluoroelastomers. These examples give the volume swell and weight
gain of materials soaked in methanol for 72 hrs at 21.degree. C.
Example 19 is a standard fluoroelastomer compound based on FE 5642Q
(100 phr FE 5642Q, 30 phr carbon black N990, 3 phr MgO, 6 phr
Ca(OH).sub.2 and 1 phr Struktol WS280). Examples 20 and 21 are the
materials of Examples 4 and 15 respectively. A comparison of the
two materials of the invention (Examples 20 and 21) with that of
the thermoset rubber compound (Example 19) indicates vastly
improved fluid resistance of the compositions of the invention to
methanol.
6TABLE 6 EXAMPLES 19 20 21 Volume swell, % 116 45 43 Weight gain, %
49 19 18
EXAMPLES 22 THROUGH 26
[0044] Compositions of Examples 22 through 26 illustrate the effect
on physical properties of variations in filler level as well as
fluoroelastomer dipolymer grade used as part of the rubber
phase.
7TABLE 7 EXAMPLES 22 23 24 25 26 wt. % wt. % wt. % wt. % wt. %
MATERIAL FE 5640Q 0.0 41.8 21.5 0.0 44.3 FE 5642Q 41.8 0.0 21.5
44.3 0.0 BRE 7231X 13.9 13.9 14.3 14.8 14.8 E14944 30.0 30.0 30.9
31.8 31.8 Carbon Black N990 8.4 8.4 5.7 3.0 3.0 Ca(OH)2 3.9 3.9 4.0
4.1 4.1 MgO 2.0 2.0 2.0 2.1 2.1 Total 100.00 100.00 99.9 100.1
100.1 Physical Properties Hardness Shore A 87 88 85 84 86 UTS Mpa
7.6 7.7 6.9 6.6 6.9 EB % 176 165 178 225 181 M100 Mpa 5.6 6.0 5.3
4.5 5.2 Comp. Set % 56 69 68 72 67 (70 hrs @ 125.degree. C.)
Methanol Resistance (70 hrs @ 21.degree. C.) Volume Swell % Weight
gain %
[0045] The TPV of this invention is believed to have particular
utility in fuel systems, especially for automotive applications.
Possible applications are in automotive fuel tank sealing, or
sealing and gasketing, of the various components associated with
the fuel system, such as fuel valves. In addition, since the
material is thermoplastic it can be extruded as well as injection
molded. This opens possibilities for use as a hose material or a
component of a hose (cover, inner layer, etc . . . ), including
fuel system hoses.
[0046] There are now described three additional articles
manufactured from the material of this invention. These articles
are: O-rings, radial shaft seals and gaskets for sealing the plate
stack of PEM (Proton Exchange Membrane) fuel cells. Each of these
applications will benefit from the advantages of this invention.
These include outstanding physical properties, retention of
properties in hot air environments, resistance to fluids
(particularly hydrocarbon oils), ease of processing and
recycleability. A description of each application is now given:
EXAMPLE 27
O-RINGS
[0047] A 16 cavity compression mold was used to produce 16 O-rings
of 5 different sizes from the material Example 16 in Provisional
Patent Application Serial No. 60/168,414. The molding cycle
consisted of compressing the material at 490.degree. F. for 300
seconds in a 75 ton press and then transferring the tool to a cold
(room temperature) press and holding it under pressure for 6
minutes to cool. The OD/ID of the five O-ring sizes made are
approximately: 2.1/1.6, 1.9/1.4, 1.7/1.2, 1.5/1.0 and 1.4/0.9 mm/mm
respectively. Such O-ring components could be used for general
sealing or gasketing applications. A possible use for the O-rings
produced from material of Example 16 is, but is not necessarily
limited to, sealing applications having a continuous use
temperature of up to 150.degree. C. and in contact with hydrocarbon
based oils.
EXAMPLE 28
RADIAL SHAFT SEAL
[0048] A piece compression mold was used to produce a trim lip
radial shaft seal on a metal insert ring from the material of
Example 4 in Provisional Patent Application Serial No. 60/168,414.
The tool was preheated to 480.degree. F. and then removed from the
press. A metal case insert, which had been pretreated with an
amino-silane adhesive, was placed in the mold along with
approximately 10 grams of material. The tool was placed back in the
press and compacted for 4 minutes at 480.degree. F. Following this,
the tool was removed and transferred to a cold (room temperature)
press and held under pressure for 6 minutes to cool. Common uses of
radial shaft seal include automotive power train systems and
industrial motor applications.
EXAMPLE 29
PEM FUEL STACK SEALING
[0049] Proton Exchange Membrane (PEM) fuel cells have recently
generated a lot of commercial interest because of their potential
to power such things as residential and commercial dwellings to
transportation vehicles. A PEM fuel cell generates power by an
electro-chemical reaction occurring between two or more plates,
known as the stack. Sealing these plate stacks is a challenging
problem. The seal has to perform at about 100.degree. C., have low
permeation to gases, such as air and hydrogen, have resistance to
an assortment of heat transfer fluids (for example water and
hydrocarbon based oils), have compatibility with an assortment of
catalyst systems (for example platinum based catalysts) and have
low compression set. In addition, these gaskets are typically very
thin which results in processing challenges.
[0050] The material of this invention has been compression molded
into an approximately 4 inch by 4 inch square framed gasket having
a thickness of about 0.70 m at its thickest portion and 0.20 mm at
its thinnest. The material used was that of Example 4 in Patent
Application Serial No. 60/168,414. Molding was undertaken by
preheating the tool to 480.degree. F. and then removing it from the
75 ton press. An approximately 0.035 inch thick piece of material
was laid along the cavity of the tool and the tool was placed back
in the press. The press cycle consisted of compression for 4
minutes at 480.degree. F. Following this, the tool was removed and
transferred to a cold (room temperature) press and held under
pressure for 6 minutes cool.
[0051] By the term seal-gasket product as used herein it is meant a
seal or a gasket member which is used to form a sealing engagement
between two or more metal or plastic members (and preferably being
metal).
[0052] While it will be apparent that the preferred embodiments of
the invention disclosed are well calculated to fulfill the objects,
benefits, and advantages of the invention, it will be appreciated
that the invention is susceptible to modification, variation and
change without departing from the proper scope or fair meaning of
the subjoined claims.
* * * * *