U.S. patent application number 15/287281 was filed with the patent office on 2017-06-29 for anti-extrusion compositions for sealing and wear components.
This patent application is currently assigned to Delsper LP. The applicant listed for this patent is Delsper LP. Invention is credited to Burak BekisIi, William F. Burgoyne, Charles P. Burke, Ronald R. Campbell, Kerry A. Drake.
Application Number | 20170183445 15/287281 |
Document ID | / |
Family ID | 51223623 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170183445 |
Kind Code |
A1 |
Drake; Kerry A. ; et
al. |
June 29, 2017 |
Anti-Extrusion Compositions for Sealing and Wear Components
Abstract
A method and compositions are described which improve extrusion-
and creep-resistance of components for use in a high temperature
applications including sealing elements and seal connectors among
others. The method includes providing a composition having an
aromatic polymer and a crosslinking compound, and subjecting the
composition to a heat molding process to form the component and
crosslink the aromatic polymer.
Inventors: |
Drake; Kerry A.; (Red Hill,
PA) ; Burke; Charles P.; (Magnolia, TX) ;
Campbell; Ronald R.; (Harleysville, PA) ; Burgoyne;
William F.; (Bethlehem, PA) ; BekisIi; Burak;
(Conroe, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Delsper LP |
Kulpsville |
PA |
US |
|
|
Assignee: |
Delsper LP
|
Family ID: |
51223623 |
Appl. No.: |
15/287281 |
Filed: |
October 6, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14825372 |
Aug 13, 2015 |
9475938 |
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15287281 |
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|
14165497 |
Jan 27, 2014 |
9127138 |
|
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14825372 |
|
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|
61757697 |
Jan 28, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 2261/3442 20130101;
C08G 2261/76 20130101; C08L 79/04 20130101; C08G 65/48 20130101;
C08G 73/18 20130101; C08L 73/00 20130101; C08G 2261/135 20130101;
C08K 5/00 20130101; C08L 65/00 20130101; C08G 73/14 20130101; C08G
2650/40 20130101; C08G 2261/312 20130101; C08L 79/08 20130101; C08L
77/10 20130101; C08L 65/02 20130101; C09K 3/1006 20130101; C08L
81/06 20130101; C08G 2261/3142 20130101; C08L 71/12 20130101; C08L
75/02 20130101; C08K 5/053 20130101; C08G 61/127 20130101; C08K
5/053 20130101; C08L 71/12 20130101; C08L 75/04 20130101 |
International
Class: |
C08G 61/12 20060101
C08G061/12; C08L 65/02 20060101 C08L065/02; C08K 5/00 20060101
C08K005/00; C08L 73/00 20060101 C08L073/00; C08G 73/18 20060101
C08G073/18; C08G 65/48 20060101 C08G065/48 |
Claims
1. (canceled)
2. A composition for formation of an extrusion-resistant sealing
member, comprising: a polymer selected from the group consisting of
a polyarylene polymer, a polysulfone, a polyphenylenesulfide, a
polyimide, a polyamide, a polyurea, a polyurethane, a
polyphthalamide, a polyamide-imide, an aramid, a polybenzimidazole,
and blends, copolymers and derivatives thereof. a crosslinking
compound, wherein the crosslinking compound has a structure
according to formula (II): ##STR00018## wherein A is an arene
moiety having a molecular weight of less than 10,000 g/mol, R.sup.1
is selected from a group consisting of hydroxide (--OH), amine
(--NH.sub.2), halide, ether, ester or amide, and x=2.0 to 6.0.
3. The composition of claim 2, wherein the polymer is a polyarylene
polymer, a polysulfone polymer, or a blend, a copolymer, or a
derivative thereof.
4. The composition of claim 3, wherein the polyarylene polymer is
one or more of a polyetheretherketone (PEEK), a polyetherketone
(PEK), a polyetherketoneetherketoneketone (PEKEKK), a
polyetherketoneketone (PEKK), a polysulfone (PSU), a
polyethersulfone (PES), a polyarylsulfone (PAS), and blends,
copolymers and derivatives thereof.
5. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches produces a
static extrusion height of no greater than 0.11 mm when tested at
290.degree. C. under a pressure of 35,000 psi in a load cell having
a 0.51 mm extrusion gap.
6. The composition of claim 5, wherein the extrusion height after
one hour is no greater than 0.21 mm.
7. The composition of claim 6, wherein the extrusion height after
three hours is no greater than 0.24 mm.
8. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches has a tensile
modulus at 200.degree. C. of at least 0.99 GPa as measured in
accordance with ASTM D638.
9. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches has a
post-yield tensile strength at 200.degree. C. and at 10% strain of
at least 43.2 GPa as measured in accordance with ASTM D638.
10. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches has a
compressive strength at 200.degree. C. of at least 121.9 MPa as
measured in accordance with ASTM D690.
11. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches and when
tested according to ASTM D2990 at 260.degree. C. with a stress of
10 MPa has an instant creep modulus of at least 4.95 MPa.
12. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches and when
tested according to ASTM D2990 at 260.degree. C. with a stress of
10 MPa has a creep modulus at 1 hour of at least 4.31 MPa.
13. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches and when
tested according to ASTM D2990 at 260.degree. C. with a stress of
10 MPa has a creep modulus at 3 hours of at least 4.26 MPa.
14. The composition of claim 2, wherein the composition when formed
into a molded article having a cylindrical configuration with a
diameter of 0.5 inches and a thickness of 0.12 inches and when
tested according to ASTM D2990 at 260.degree. C. with a stress of
10 MPa has a creep modulus at 7.5 hours of at least 4.12 MPa.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.120
to and is a continuation application of U.S. patent application
Ser. No. 14/825,372, filed Aug. 13, 2015, entitled, "Anti-Extrusion
Compositions for Sealing and Wear Components," which claims the
benefit under 35 U.S.C. .sctn.120 to and is a continuation
application of U.S. patent application Ser. No. 14/165,497, filed
Jan. 27, 2014, now U.S. Pat. No. 9,127,138, entitled,
"Anti-Extrusion Compositions for Sealing and Wear Components",
which claims the benefit under 35 U.S.C. .sctn.119(e) to U.S.
Provisional Patent Application No. 61/757,697, filed Jan. 28, 2013,
entitled, "Anti-Extrusion Compositions for Sealing and Wear
Components," the disclosures of which are incorporated herein in
their entirety.
BACKGROUND OF THE INVENTION
[0002] Field of the Invention
[0003] The invention relates to the field of high temperature
polymers and their use in sealing and other wear-resistant
components.
[0004] Description of Related Art
[0005] Sealing components and other wear resistant materials can be
used in very rigorous and demanding environments. Their wear and
mechanical properties are very critical to their applicability and
useful life. For example, sealing components are typically formed
of elastomeric materials that are situated in a gland. In one
application, an annular seal may fit within a gland and be
installed to seal a gap between surfaces, e.g., a seal may be
installed around a shaft that fits within a bore and the bore can
be configured to have a gland for receiving the seal. In many
instances, the seal is not installed alone and is part of a seal
assembly. Such assemblies may include back-up rings and other
components. Seals and seal assemblies are usually constructed to
support the primary sealing element, generally formed of an
elastomeric material, to prevent extrusion of that material into
the gland and into the space or gap between the sealing
surfaces.
[0006] When temperatures of use become high, pure elastomeric seals
may not be able to provide sufficient sealing force to prevent
leakage and/or may extrude into the gap between sealing surfaces,
e.g., a shaft and a seal. Under such conditions, thermoplastic
materials with higher shear strengths may be used to isolate the
soft elastomer component from the gap between the sealing surfaces
to assist in resisting extrusion. Combination of harder and softer
materials are sometimes also used so that softer materials (such
as, for example, polytetrafluoroethylene (PTFE) or other
fluoropolymeric materials) are prevented from extruding into the
gap by stiffer thermoplastic antiextrusion components. Such
materials are used in unidirectional and bidirectional sealing
assemblies.
[0007] Materials that have been used as antiextrusion components
include polyetherether ketone (PEEK) and similar polyketones.
Continuous use temperatures for such materials range from about
240.degree. C. to about 260.degree. C., including for commercial
polyarylketones, such as Victrex.RTM. polyarylenes.
[0008] In use, at elevated temperatures, polyketones are well above
their glass transition temperatures (T.sub.g). For example, PEEK is
semicrystalline and has a T.sub.g of 143.degree. C. Other
polyketones such as Victrex.RTM. PEK and PEKEKK have respective
glass transition temperatures of 152.degree. C. and 162.degree.
C.
[0009] As semicrystalline materials are used above their glass
transition temperatures, they tend to demonstrate lower mechanical
properties in service and there is a corresponding drop in
performance. With reference to FIGS. 1 and 2, this effect can be
seen as PEEK rings are loaded below and above their glass
transition temperatures, respectively, and significant differences
in extrusion resistance can be seen. FIG. 2 shows a 60% increase in
extrusion at a pressure that is 50% lower for the same loading
period.
[0010] Such extrusion issues are also problematic in the area of
electrical connectors. Such connectors are used to relay electrical
signals from sensors to electronics in downhole oil exploration
tools. They function also as bulkhead seals and are the last line
of defense against destruction of electronics in an oil exploration
tool when the tool suffers a catastrophic failure. Such seals must
be able to withstand high pressure for extended periods of time at
elevated temperature. Unfortunately, many downhole oilfield
products are used at or above the T.sub.g of various commercial
polyketones, so that severe extrusion can take place. Often such
extrusion results in failure of the part as a seal, allowing either
moisture to leak through the seal or for the part to deform so it
no longer performs properly mechanically. An example of this
behavior can be seen in FIG. 3, which demonstrates extrusion on an
electrical connector.
[0011] Attempts to enhance the properties of PEEK have been
attempted. Cross-linking has been widely recognized as one way to
modify high temperature polymeric materials. Several inventions
have been aimed at improving the high temperature performance of
organic polymers by using cross-linking within the polymers by
cross-linking to itself, grafting cross-linking compounds to the
polymer, or by incorporating cross-linking compounds into the
polymer such as by blending.
[0012] U.S. Pat. No. 5,173,542 discloses use of bistriazene
compounds for cross-linking polyimides, polyarylene ketones,
polyarylether sulfones, polyquinolines, polyquinoxalines, and
non-aromatic fluoropolymers. The resulting cross-linked polymers
are useful as interlayer insulators in multilayer integrated
circuits. The patent discusses difficulties in the art encountered
includes controlling the cross-linking process in aromatic polymers
to enhance properties. It proposes a bistriazene cross-linking
structure and method to enhance chemical resistance and reduce
crazing so that useful interlayer materials may be formed.
[0013] Other attempts to cross-link polymers to enhance high
temperature properties have encountered difficulty with respect to
thermal stability of the polymer. Other issues arise in terms of
control of the rate and extent of cross-linking.
[0014] U.S. Pat. No. 5,874,516, which is assigned to the Applicant
of the present application and is incorporated herein by reference
in relevant part, shows polyarylene ether polymers that are
thermally stable, have low dielectric constants, low moisture
absorption and low moisture outgassing. The polymers further have a
structure that may cross-link to itself or can be cross-linked
using a cross-linking agent.
[0015] U.S. Pat. No. 6,060,170, which is assigned to the Applicant
of the present application and is incorporated herein by reference
in relevant part, describes the use of polyarylene ether polymer
compositions having aromatic groups grafted on the polyarylene
ether polymer backbone. The grafts allow for crosslinking of the
polymers in a temperature range of about 200.degree. C. to about
450.degree. C. This patent discloses dissolving the polymer in an
appropriate solvent for grafting the cross-linking group(s). Such
required process steps can sometimes make grafting difficult or not
practical in certain types of polymers or in certain polymeric
structures, including, e.g., PEEK.
[0016] A further patent, U.S. Pat. No. 5,658,994 discusses a
polyarylene ether polymer in which the polymer may be crosslinked,
e.g., by crosslinking itself through exposure to temperatures of
greater than about 350.degree. C. or by use of a crosslinking
agent. The patent also describes end-capping the polymer using
known end-capping agents, such as phenylethynyl, benzocyclobutene,
ethynyl, and nitrile. Limited crosslinking is present at the end of
the chain such that relevant properties, i.e., the glass transition
temperature, the chemical resistance and the mechanical properties,
are not enhanced sufficiently for all high temperature
applications,
[0017] Further developments in improving polyarylene ether polymer
properties are described in International Patent Publication No. WO
2010/019488, which describes use of per(phenylethynyl)arenes as
additives for polyarylene ethers, polyimides, polyureas,
polyurethanes and polysulfones. The application discusses formation
of a semi-interpenetrating polymer network between two polymers to
improve properties.
[0018] Previous attempts have also been made to control where
crosslinks form along high glass transition polymers to garner
desired mechanical properties and prepare useful high temperature
polymers. U.S. Pat. No. 5,658,994, noted above, and incorporated
herein by reference in relevant part, demonstrates the use of a
polyarylene ether in low dielectric interlayers which may be
cross-linked, in one instance, by cross-linking the polymer to
itself, through exposure to temperatures of greater than about
350.degree. C. or alternatively by using a crosslinking agent. In
that patent, as well as in U.S. Pat. No. 5,874,516, cross-linking
occurs at the ends of the polymer backbone using known end capping
agents, such as phenylethynyl, benzocyclobutene, ethynyl and
nitrile. There is still a need to control the rate and extent of
cross-linking and the location of crosslinks.
[0019] Co-pending International Application No. PCT/US2011/061413
describes a composition having a crosslinking compound of the
structure:
##STR00001##
wherein R is OH, NH.sub.2, halide, ester, amine, ether or amide,
and x is 2-6 and A is an arene moiety having a molecular weight of
less than about 10,000. When reacted with an aromatic polymer, such
as a polyarylene ketone, it forms a thermally stable, cross-linked
polymer. This technology allows for crosslinking of polymers
previously believed non-crosslinkable, and which are thermally
stable up to temperatures greater than 260.degree. C. and even
greater than 400.degree. C. or more, depending on the polymer so
modified, i.e., polysulfones, polyimides, polyamides,
polyetherketones and other polyarylene ketones, polyureas,
polyurethanes, polyphthalamides, polyamide-imides, aramids, and
polybenzimidazoles.
[0020] Co-Pending U.S. Provisional Patent Application No.
61/716,800, co-owned by the Applicant of the present application
describes a cross-linking composition comprising a cross-linking
compound and a cross-linking reaction additive selected from an
organic acid and/or an acetate compound. The cross-linking compound
has a structure according to formula (I):
##STR00002##
wherein A is an arene moiety having a molecular weight of less than
10,000 g/mol, R.sup.1 is selected from a group consisting of
hydroxide (--OH), amine (--NH.sub.2), halide, ether, ester, or
amide, and x=2.0 to 6.0, wherein the cross-linking reaction
additive is capable of reacting with the cross-linking compound to
form a reactive intermediate in the form of an oligomer, which
reactive intermediate oligomer is capable of cross-linking an
organic polymer.
[0021] In one embodiment, the cross-linking reaction additive is an
organic acid which may be glacial acetic acid, formic acid, and/or
benzoic acid. In another embodiment, the cross-linking reaction
additive may be an acetate compound that a structure according to
formula (III):
##STR00003##
[0022] wherein M is a Group I or a Group II metal; and R.sup.2 is
an alkyl, aryl, or aralkyl group, wherein the alkyl group is a
hydrocarbon group of 1 to about 15 carbon atoms having 0 to about 5
ester or ether groups along or in the chain of the hydrocarbon
group, wherein R.sup.2 may have 0 to about 5 functional groups that
may be one or more of sulfate, phosphate, hydroxyl, carbonyl,
ester, halide, mercapto or potassium. The acetate compound may be
lithium acetate hydrate, sodium acetate and/or potassium acetate,
and salts and derivatives thereof. These cross-linking compositions
allow for control of a cross-linking reaction when combined with an
organic polymer and can enable a lower rate of thermal cure, giving
a broader window and better control during heat mold of the
resultant cross-linked organic polymer. Such control can enable
formation of polymers that are suitable for extreme conditions such
as down-hole end applications.
[0023] While polyimides and polyamide-imide copolymers have higher
glass transition temperatures of about 260.degree. C. or more, they
tend to not be useful in strong acids, bases or aqueous
environments, as they suffer more easily from chemical attack. As a
result, while their operating temperatures are more attractive,
their chemical resistance properties limit their usefulness in
sealing applications where the fluid medium is water based or
otherwise harmful to the material. For example, testing of
polyimide by applicant has shown about an 80% loss in properties
after aging at 200.degree. C. for three days in steam, using
ASTM-D790 to test the flexural modulus.
[0024] Fully aromatic polysulfones such as polyether sulfone (PES)
and polyphenyl sulfone (PPSU) may be used in such end applications,
but their amorphous nature creates issues in that they are
vulnerable to stress cracking in the presence of strong acids and
bases. Due to the possibility of the amorphous polymers flowing at
temperatures near their glass transition temperature over time,
continuous use temperatures are typically set about 30.degree. C.
to 40.degree. C. below the glass transition temperature. Thus, for
continuous use for a polysulfone (PSU), the temperature is
recommended to be set at 180.degree. C. when the glass transition
temperature is about 220.degree. C.
[0025] Other problems encountered in more demanding end uses
exposed to harsh chemicals, water and/or steam, include problems
associated with a plasticizer effect caused when the polymer
absorbs the chemical which can enhance motion of molecular chains
and create a depression of the glass transition temperature from
its normal state in the unswollen polymer.
[0026] A further issue is associated with creep. When polymers
operate above their glass transition temperature, creep is a
limiting factor for seal components which can deform under harsh
conditions. Thus, to improve mechanical properties, prevent creep
and resist extrusion, most high temperature polymers in use are
filled for use as backup rings or molded components. The downside
of use of fillers is that it typically drops the ductility
tremendously. For example, unfilled PEEK has a tensile elongation
of about 40%, whereas 30% carbon-filled PEEK has a tensile
elongation at break of only 1.7%. Thus the material becomes more
brittle from the strengthening filler, and the brittleness can
result in part cracking under prolonged loadings. The use of
fillers also causes a differential coefficient of thermal expansion
in the mold versus the transverse direction of the molded parts.
This can also cause significant molded-in stress. The end result is
cracking over time due to creep rupture, even when a part is not
under a significant load.
[0027] Thus, there is a need in the art for better and higher
performing polymeric materials for sealing components, seal
connectors and similar parts that can operate at high service
temperatures associated with oilfield and other harsh conditions
and industrial uses, but still maintain good mechanical
performance, resist extrusion of the seal or connector material
into a gap between two surfaces to be sealed or along the pin, and
resist creep when in use, without becoming brittle and
significantly losing its ductility.
BRIEF SUMMARY OF THE INVENTION
[0028] The invention includes a composition for formation of an
extrusion-resistant sealing member, comprising: an aromatic
polymer; and a crosslinking compound. The polymer may be one or
more of a polyarylene polymer, a polysulfone, a polyphenylene
sulfide, a polyimide, a polyamide, a polyurea, a polyurethane, a
polyththalamide, a polyamide-imide, an aramid, a polybenzimidazole,
and blends, copolymers and derivatives thereof. Preferably, the
aromatic polymer is a polyarylene polymer and/or a polysulfone
polymer, and blends, copolymers and derivatives thereof.
[0029] When the aromatic polymer is a polyarylene ether polymer, it
may have repeating having units of structure according to formula
(IV) below:
O--Ar.sub.1--O--Ar.sub.2 .sub.m O--Ar.sub.3--O--Ar.sub.4 .sub.n
(IV)
wherein Ar.sub.1, Ar.sub.2, Ar.sub.3 and Ar.sub.4 are identical or
different aryl radicals, m is 0 to 1, and n is 1-m.
[0030] If the aromatic polymer is a polyarylene-type polymer, it is
preferably at least one of polyetheretherketone, polyetherketone,
polyetherketoneetherketoneketone, polyetherketoneketone,
polysulfone, polyphenylene sulfide, polyethersulfone,
polyarylsulfone, and blends, copolymers and derivatives
thereof.
[0031] The crosslinking compound preferably has a structure
according to formula (II) below:
##STR00004##
wherein A is an arene moiety having a molecular weight of less than
10,000 g/mol, R.sup.1 is selected from a group consisting of
hydroxide (--OH), amine (--NH.sub.2), halide, ether, ester, or
amide, and x=2.0 to 6.0.
[0032] The crosslinking compound is preferably
9,9'-(biphenyl-4,4'-diyl)bis(9H-fluoren-9-ol) and has a general
structure according to formula (V):
##STR00005##
[0033] The composition noted above may also include a cross-linking
reaction additive capable of reacting with the cross-linking
compound to form a reactive intermediate in the form of an
oligomer, which reactive intermediate oligomer is capable of
cross-linking an organic polymer. The cross-linking reaction
additive may be an organic acid which may be glacial acetic acid,
formic acid, and/or benzoic acid. In another embodiment, the
cross-linking reaction additive may be an acetate compound that has
a structure according to formula (III):
##STR00006##
wherein M is a Group I or a Group II metal; and R.sup.2 is an
alkyl, aryl, or aralkyl group, wherein the alkyl group is a
hydrocarbon group of 1 to about 15 carbon atoms having 0 to about 5
ester or ether groups along or in the chain of the hydrocarbon
group, wherein R.sup.2 has 0 to about 5 functional groups.
[0034] Preferably, the compositions of the invention are unfilled
compositions providing enhanced ductility in use, although, they
may be filled if the user desires to fill the composition.
[0035] The invention also includes sealing components of a sealing
assembly formed by a method comprising the step of crosslinking a
composition as described herein.
[0036] A sealing connector is also included herein having a seal
connector body formed by a method comprising the step of
crosslinking a composition as described herein.
[0037] The invention further includes a method of improving
extrusion- and creep-resistance of a component for use in a high
temperature sealing element or seal connector, comprising,
providing a composition comprising an aromatic polymer and a
crosslinking compound, and subjecting the composition to a heat
molding process to form the component and crosslink the aromatic
polymer. The composition is preferably unfilled. The aromatic
polymer and cross-linking compound may be any of those noted herein
and described above, and the composition may also include the
optional cross-linking reaction additive.
[0038] Also included herein are sealing components and sealing
connectors formed by the method described above, wherein the
composition may be filled or unfilled. The sealing component is a
seal back-up element, a packer element, a labyrinth seal or a
dual-lip sealing component.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0039] The foregoing summary, as well as the following detailed
description of preferred embodiments of the invention, will be
better understood when read in conjunction with the appended
drawings. For the purpose of illustrating the invention, there is
shown in the drawings embodiments which are presently preferred. It
should be understood, however, that the invention is not limited to
the precise arrangements and instrumentalities shown. In the
drawings:
[0040] FIG. 1 is a photographic representation of a Prior Art PEEK
back-up ring tested at 300.degree. F. (149.degree. C.) with 21,000
psi applied hydrostatic pressure to the top surface for 24 hours,
wherein extrusion of 0.19 mm was measured on the outer edge of the
ring;
[0041] FIG. 2 is a photographic representation of the bottom
surface of a Prior Art PEEK back-up ring tested at 450.degree. F.
(237.degree. C.) with 11,000 psi applied hydrostatic pressure to
the top surface for 24 hours. This loading at high temperature
resulted in extrusion of 0.30 mm, a 60% increase in extrusion over
that in FIG. 1, but at only one-half the applied pressure;
[0042] FIG. 3 is a Prior Art SealConnect.RTM. connector formed of
polyether ketone (PEK) before and after application of 20,000 psi
hydrostatic pressure and 300.degree. F. (149.degree. C.) for 24
hours;
[0043] FIG. 4 is a schematic representation of a backup ring
extrusion simulation test used in Example 1;
[0044] FIG. 5 is photographic representation of a 17% crosslinked
PEEK backup ring cut in cross section, after the 450.degree. F. and
40,000 psi functional test for a sample made according to an
embodiment of the invention in Example 1 and showing very minor
extrusion in the sample;
[0045] FIG. 5A is a photographic representation of a PEEK back-up
ring cut in cross-section after being tested at the same conditions
as the 17% cross-linked PEEK of FIG. 5 according to Example 1,
wherein the PEEK back-up ring shows a 0.030 in. extrusion;
[0046] FIG. 6 is a photographic representation of a sample of a
standard 40% carbon-filled PEEK backup ring cut in cross-section
for comparative purposes after functional testing at 400.degree. F.
and 30,000 psi, showing cracking amounting to a catastrophic
failure, and source for potential leaking for fluid across a seal
stack if put into use;
[0047] FIG. 7 is a graphical representation of results of the
simulated backup ring extrusion test in Example 1;
[0048] FIG. 8 is a graphical representation of the extrusion
resistance for the samples tested in the extrusion product function
test in Example 1;
[0049] FIG. 9 is a graphical representation of the mechanical
properties of PEEK, PEKEKK and cross-linked PEEK samples of Example
3;
[0050] FIG. 10 is a graphical representation of the relationship of
strain against time for creep tests run in Example 3;
[0051] FIG. 11 is a graphical representation in chart form of the
Modulus of the samples tested in Example 3 and as set forth in
Table 4;
[0052] FIG. 12 is a side-elevational view, partially in
longitudinal cross-section of a sample connector demonstrating
relational distances in the connector for understanding deformation
data in Example 4;
[0053] FIG. 13 is a graphical representation of pressure and
temperature against time to illustrate the temperature and pressure
cycles for testing in Example 4;
[0054] FIG. 14 is a photographic representation of connectors after
high temperature and high pressure deformation testing in Example
4;
[0055] FIG. 15 is a graphical representation of deformation of
distance d.sub.1 of FIG. 12 measured in the noted samples as tested
for deformation in Example 4; and
[0056] FIG. 16 is a prior art graph from Parallel Plate Rheology of
Blend 3, at 380.degree. C., referenced to J. Mercel et al.,
"Thermal Analysis of Polymers: Fundamentals and Applications," p.
445, Wiley, ed. 1 (2009).
DETAILED DESCRIPTION OF THE INVENTION
[0057] Applicants herein describe compositions and methods of
making sealing components, seal connectors and the like that resist
creep and extrusion and maintain good mechanical properties at high
continuous use temperatures and in end uses requiring good chemical
resistance as well.
[0058] The composition described herein are extrusion-resistant and
creep-resistant, while maintaining good sealing and ductility
properties. The compositions are useful for forming sealing members
or sealing connectors and similar components used in harsh and/or
high temperature conditions. As used herein, a "high temperature"
environment is meant in its ordinary meaning, and one skilled in
the art would know that high temperature environments include those
in which service temperatures are at or above the glass transition
temperature of the polymer in service. Concerning the polymers
discussed herein, such high temperature environments are typically
those over 177.degree. C. (350.degree. F.). The compositions
include an aromatic polymer and a crosslinking compound and may
include optional cross-linking reaction additives if desired. Upon
crosslinking the compositions, a component may be formed having the
desired high-temperature properties. The cross-linking reactions
herein raise the glass transition temperature of the resulting
product such that in use, it functions better and resists
extrusion. The improvement of the properties is far better than
expected allowing for use of unfilled compositions in high
temperature and/or harsh conditions such as downhole environments.
This is a significant unexpected advantage in that the user can
avoid having to fill the compound to achieve desired mechanical
properties in use and to help resist creep. Instead, the user is
able to maintain good mechanical properties, resist creep and
extrusion while keeping the desired sealing ductility and tensile
elongation that make sealing components function well in the
gland.
[0059] The polymer used herein may be one or more of aromatic
polymers known and/or selected for high temperature or
creep-resistant use, including polyarylene polymers, polysulfones,
polyphenylenesulfides, polyimides, polyamides, polyureas,
polyurethanes, polyththalamides, polyamide-imides, aramids,
polybenzimidazoles, and blends, copolymers and derivatives thereof.
Preferably, the aromatic polymer is a polyarylene polymer and/or a
polysulfone polymer, and blends, copolymers and derivatives
thereof. If the aromatic polymer is a polyarylene-type polymer, it
is preferably at least one of polyetheretherketone (PEEK),
polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK),
polyetherketoneketone (PEKK), polysulfone (PSU), polyethersulfone
(PES), polyarylsulfone (PAS), and blends, copolymers and
derivatives thereof.
[0060] When the aromatic polymer is a polyarylene ether polymer, it
may have repeating having units of structure according to formula
(IV) below:
O--Ar.sub.1--O--Ar.sub.2 .sub.m O--Ar.sub.3--O--Ar.sub.4 .sub.n
(IV)
wherein Ar.sub.1, Ar.sub.2, Ar.sub.3 and Ar.sub.4 are identical or
different aryl radicals, m is 0 to 1, and n is 1-m.
[0061] In one preferred embodiment, the organic polymer is a
polyarylene ether having a structure according to the general
structure above wherein n is 0 and m is 1, with repeating units
according formula (VI) and having a number average molecular weight
(Mn) of about 10,000 to about 30,000:
##STR00007##
Such organic polymers may be obtained commercially for example, as
Ultura from Greene, Tweed and Co., Inc., Kulpsville, Pa.
[0062] The crosslinking compound preferably has a structure
according to formula (II) below:
##STR00008##
wherein A is an arene moiety having a molecular weight of less than
10,000 g/mol, R.sup.1 is selected from a group consisting of
hydroxide (--OH), amine (--NH.sub.2), halide, ether, ester, or
amide, and x=2.0 to 6.0.
[0063] The crosslinking compound is preferably
9,9'-(biphenyl-4,4'-diyl)bis(9H-fluoren-9-ol) and has a general
structure according to formula (V):
##STR00009##
[0064] The cross-linking compound(s) if used with an optional
cross-linking reaction additive(s) can be reacted to form a
reactive oligomerized cross-linking intermediates either in situ
during thermal molding with the cross-linkable organic polymer,
and/or by reacting prior to combining with a cross-linkable organic
polymer and then heat molding to form an article. IF the additive
is not used, the crosslinking compound(s) and the organic
polymer(s) can be reacted prior to molding, for example, in a
solvent reaction, but are preferably compounded and include
non-solvent precipitation or mechanical blending. One preferred
method is making a powder blend via mechanical mixing. Mechanical
blending may be done by a variety of methods, including mechanical
mixing via twin screw extrusion.
[0065] If a cross-linking additive is used to form a reactive
intermediate, the intermediate oligomer reaction product of the
cross-linking compound with the crosslinking reaction additive
enables control of a cross-linking reaction when combined with an
organic polymer and can enable a lower rate of thermal cure, to
allow a broader window and better control during heat molding of
the resultant cross-linked organic polymer.
[0066] In general, formation of cross-links in an organic polymer
cross-linking to itself or in an organic polymer composition
including an unmodified cross-linking compound may be completed
within about 2 minutes at about 380.degree. C., the typical
processing temperature of polyetherether ketone (PEEK). The extent
of this reaction can be tracked by dynamic viscosity measurements.
Two methods are often used to judge when a reaction may be
completed. The point where storage modulus G' equals Loss modulus
G'', called the crossover point or gel point, indicates the onset
of gel formation where cross-linking has produced an
interconnected. As curing continues, G' will increase, which is an
indication of cross-link density. As curing continues, eventually
G' will level off, which indicates that most curing is completed.
The inflection point G', which indicates onset of vitrification can
also be used in cases where no obvious cross-over point can be
determined. (See FIG. 16). The time required to attain G', G''
crossover or the onset of vitrification can be used as the upper
limit of process time for a thermosetting material.
[0067] Utilization of one or more cross-linking reaction
additive(s) can assist in providing polymers with even higher glass
transition temperatures and higher cross-link density if desired.
Polymers with high thermal stability of up to 500.degree. C. and
high crosslink density, while desirable, display a very high melt
viscosity before further processing, and thus are very difficult to
melt process. As curing of the cross-linked polymer may be
initiated during heat molding, it is desirable to control when
cross-linking begins. If the rate of cross-linking is not
controlled before molding of a composition into a final article,
the article of manufacture may begin to prematurely cure before or
during heat molding or proceed too rapidly causing incomplete mold
fill, equipment damage, and inferior properties in the article.
Thus, the additive can provide control of the rate of cross-link
formation in an organic polymer for reactions in polymers where
control is more difficult.
[0068] The addition of the optional cross-linking reaction additive
to the cross-linking compound used for cross-linking the organic
aromatic polymers herein can delay the onset of cross-linking in
the organic polymer for as much as several minutes to allow for
rapid processing and shaping of the resultant organic polymer
structures in a controlled manner.
[0069] One or more cross-linking compounds is/are present in the
cross-linking composition and organic polymer compositions herein.
Preferably, the cross-linking compound has a structure according to
formula (II):
##STR00010##
wherein A is an arene moiety having a molecular weight of less than
10,000 g/mol. R.sup.1 can be hydroxide (--OH), amine (--NH.sub.2),
halide, ether, ester, or amide, and x is about 2.0 to about
6.0.
[0070] The arene moiety A on the cross-linking compound above
provides the cross-link site for forming more complex cross-linking
compound structures, including, for example, without
limitation:
##STR00011## ##STR00012##
[0071] The arene moiety A may be varied to have different
structures, including, but not limited to the following:
##STR00013##
[0072] The arene moiety A is most preferably the diradical of
4,4'-biphenyl, or
##STR00014##
The arene moiety A may also be functionalized, if desired, using
one or more functional groups such as, for example, and without
limitation, sulfate, phosphate, hydroxyl, carbonyl, ester, halide,
or mercapto.
[0073] The cross-linking compound can be formed, for example, by
treating a halogenated arene with an alkyllithium in order to
exchange the halogen with lithium, followed by the addition of
9-florenone and acid. This method of formation is described and
shown in more detail in co-pending International Patent Application
No. PCT/US2011/061413, which is incorporated herein by reference in
relevant part.
[0074] The cross-linking composition and the organic polymer
composition may also contain an optional cross-linking reaction
additive. The cross-linking reaction additive(s) include organic
acids and/or acetate compounds, which can promote oligomerization
of the cross-linking compound. In one embodiment, the
oligomerization can be carried out by acid catalysis using one or
more organic acid(s), including glacial acetic acid, acetic acid,
formic acid, lactic acid, citric acid, oxalic acid, uric acid,
benzoic acid and similar compounds. An oligomerization reaction
using one of the cross-linking compounds listed above is as
follows:
##STR00015##
[0075] In another embodiment, the cross-linking reaction additive
may be an acetate compound that has a structure according to
formula (III):
##STR00016##
wherein M is a Group I or a Group II metal. R.sup.2 in Formula (II)
may preferably be an alkyl, aryl or aralkyl group. For example,
R.sup.2 may be a hydrocarbon group of 1 to about 15 carbon atoms,
including normal chain and isomeric forms of methyl, ethyl, propyl,
butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, ethenyl,
propenyl, butenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl,
and the like. R.sup.2 may also have from 0 to about 5 ester or
ether groups along or in a chain of the hydrocarbon group. Suitable
R.sup.2 aryl and aralkyl groups, including those based on phenyl,
naphthyl, and similar groups, which may each include optional lower
alkyl groups on the aryl structure of from 0 to about 5 carbon
atoms. R.sup.2 may further include 0 to about 5 functional groups
if desired such as sulfate, phosphate, hydroxyl, carbonyl, ester,
halide, mercapto and/or potassium on the structure.
[0076] Oligomerization of the cross-linking compound with an
acetate compound can afford the same resultant oligomerized
cross-linking composition as achieved when adding an organic acid.
The cross-linking reaction additive may be lithium acetate hydrate,
sodium acetate, potassium acetate, rubidium acetate, cesium
acetate, francium acetate, beryllium acetate, magnesium acetate,
calcium acetate, strontium acetate, barium acetate, and/or radium
acetate, and salts and derivatives thereof. More preferably, the
cross-linking reaction additive is lithium acetate hydrate, sodium
acetate and/or potassium acetate, and salts and derivatives of such
compounds. An oligomerization reaction using of one of the
cross-linking compounds can proceed as follows:
##STR00017##
[0077] A cross-linking composition formed of just the cross-linking
compound and any optional crosslinking reaction additive preferably
has a weight percentage ratio of the cross-linking compound to any
cross-linking reaction additive of about 10:1 to about 10,000:1,
and more preferably about 20:1 to about 1000:1 for achieving the
best results from such an additive. In making the cross-linking
composition, in one embodiment, the components are combined prior
to addition of an organic polymer to make an organic polymer
composition. Alternatively, they may all be combined simultaneously
or the cross-linking compound simply combined with the aromatic
polymer.
[0078] The amount of the cross-linking compound in a cross-linking
composition including just the cross-linking compound and any
optional cross-linking reaction additive is preferably about 70% by
weight to about 98% by weight, more preferably about 80% by weight
to about 98% by weight, and most preferably about 85% by weight to
about 98% by weight based on the weight of the cross-linking
composition. The amount of the cross-linking reaction additive in
the cross-linking composition is preferably about 2% by weight to
about 30% by weight, more preferably about 2% by weight to about
20% by weight, and most preferably about 2% by weight to about 15%
by weight.
[0079] The organic polymer composition preferably has a weight
percentage ratio of the organic polymer to the weight of the
cross-linking compound (or combined weight of the cross-linking
compound and any optional cross-linking reaction additive) of about
1:1 to about 100:1, and more preferably about 3:1 to about 10:1 for
achieving the best results.
[0080] In making the organic polymer composition, it is preferred
that the cross-linking compound and optional cross-linking reaction
additive components if present are combined prior to addition of an
aromatic polymer to make the moldable composition. Alternatively,
they may all be combined simultaneously.
[0081] The amount of the cross-linking compound in the moldable
aromatic polymer composition is preferably about 1% by weight to
about 50% by weight, more preferably about 5% by weight to about
30% by weight, and most preferably about 8% by weight to about 24%
by weight based on the total weight of an unfilled moldable organic
composition including the cross-linking compound and the organic
polymer (and any optional crosslinking additive).
[0082] The amount of the cross-linking reaction additive, if used
in the moldable aromatic polymer composition is preferably about
0.01% by weight to about 33% by weight, more preferably about 0.1%
by weight to about 10% by weight, and most preferably about 0.2% by
weight to about 2% by weight based on the total weight of an
unfilled polymer composition including the cross-linking compound
and the organic polymer and the optional crosslinking additive.
[0083] The amount of the aromatic polymer in the moldable aromatic
polymer composition is preferably about 50% by weight to about 99%
by weight, more preferably about 70% by weight to about 95% by
weight, and most preferably about 75% by weight to about 90% by
weight based on the total weight of an unfilled polymer composition
including the cross-linking compound and the organic polymer, along
with any optional cross-linking reaction additive.
[0084] It is preferred that the compositions herein remain
unfilled, particularly with respect to strength additives that may
impact ductility and tensile elongation. However, it is also within
the scope of the invention that the organic polymer composition may
further be filled and/or reinforced and include one or more
additives to improve the modulus, impact strength, dimensional
stability, heat resistance and electrical properties of composites
and other finished articles of manufacture formed using the polymer
composition. These additive(s) can be any suitable or useful
additives known in the art or to be developed, including without
limitation continuous or discontinuous, long or short, reinforcing
fibers such as, for example, carbon fiber, glass fiber, woven glass
fiber, woven carbon fiber, aramid fiber, boron fiber, PTFE fiber,
ceramic fiber, polyamide fiber and the like; and/or one or more
fillers such as, for example, carbon black, silicate, fiberglass,
calcium sulfate, boron, ceramic, polyamide, asbestos,
fluorographite, aluminum hydroxide, barium sulfate, calcium
carbonate, magnesium carbonate, silica, alumina, aluminum nitride,
borax (sodium borate), activated carbon, pearlite, zinc
terephthalate, graphite, talc, mica, silicon carbide whiskers or
platelets, nanofillers, molybdenum disulfide, fluoropolymer
fillers, carbon nanotubes and fullerene tubes. Preferably, the
additive(s) include reinforcing fiber such as continuous or
discontinuous, long or short, carbon fiber, PTFE fiber, and/or
glass fiber.
[0085] In making the organic polymer composition, it is preferred
that the additive(s) is/are added to the composition along with or
at about the same time that the cross-linking compound is combined
with the organic polymer to make an organic polymer composition,
however, the manner of providing reinforcing fibers or other
fillers may be according to various techniques for incorporating
such materials and should not be considered to limit the scope of
the invention. The amount of additives is preferably about 0.5% by
weight to about 65% by weight based on the weight of the organic
polymer composition, and more preferably about 5.0% by weight to
about 40% by weight, and even more preferably, used very sparingly
if at all, with the most preferred embodiment being unfilled.
[0086] In addition, the organic polymer composition may further
comprise other compounding ingredients, including stabilizers,
flame retardants, pigments, plasticizers, surfactants, and/or
dispersants such as those known or to be developed in the art to
aid in the manufacturing process. The amount of the compounding
ingredients that can be combined into the organic polymer
composition, if used, is preferably about 5% by weight to about 60%
by weight of a total of such ingredients based on the weight of the
organic polymer composition, more preferably about 10% by weight to
about 40% by weight, and most preferably about 30% by weight to
about 40% by weight, and preferably significantly less than these
amounts if they are not otherwise needed.
[0087] Preferably, the compositions of the invention are unfilled
compositions providing enhanced ductility in use, although, they
may be filled if the user desires to fill the composition.
[0088] Detailed descriptions on formation of the invention are
provided in co-pending Application 61/716,800, incorporated herein
in relevant part. Heat molding to form an article of manufacture
may be accomplished by any method known or to be developed in the
art including but not limited to heat cure, cure by application of
high energy, heat cure, press cure, steam cure, a pressure cure, an
e-beam cure or cure by any combination of means, etc. Post-cure
treatments may also be applied, if desired. The organic polymer
compositions of the present invention are cured by exposing the
composition to temperatures greater than about 250.degree. C. to
about 500.degree. C., and more preferably about 350.degree. C. to
about 450.degree. C.
[0089] The compositions and/or the methods described above may be
used in or to prepare articles of manufacture of down-hole tools
and applications used in the petrochemical industry. Particularly,
the article of manufacture is selected from the group consisting of
acid-resistant coatings, chemical-casted films, extruded films,
solvent-casted films, blown films, encapsulated products,
insulation, packaging, composite cells, sealing connectors, and
sealing assemblies having back-up rings, packer elements, labyrinth
seals for pumps and MSE.RTM. seals (available from Greene, Tweed
& Co., Inc. of Kulpsville) having a dual-lip design, and other
anti-extrusion and anti-creep components in the shape of O-rings,
V-rings, U-cups, gaskets, bearings, valve seats, adapters, wiper
rings, chevron back-up rings, and tubing.
[0090] The invention also includes sealing components of a sealing
assembly formed by a method comprising the step of crosslinking a
composition as described herein.
[0091] A sealing connector is also included herein having a seal
connector body formed by a method comprising the step of
crosslinking a composition as described herein.
[0092] The invention further includes a method of improving
extrusion- and creep-resistance of a component for use in a high
temperature sealing element or seal connector, comprising,
providing a composition comprising an aromatic polymer and a
crosslinking compound, and subjecting the composition to a heat
molding process to form the component and crosslink the aromatic
polymer as described above. The composition is preferably unfilled.
The aromatic polymer and cross-linking compound may be any of those
noted herein and described above, and the composition may also
include the optional cross-linking reaction additive.
[0093] The invention will now be described in accordance with the
following, non-limiting examples:
Example 1
[0094] FIG. 4 shows a backup ring extrusion simulation test
schematic used in the following example.
[0095] Simulated Backup Ring Extrusion Test Method.
[0096] A cylindrical material specimen with a diameter of 0.5
inches and a thickness of 0.12 inches was inserted into the test
fixture shown in FIG. 4. A load was applied to the ram to generate
the specified pressure.
[0097] Tests were conducted using an MTS Servohydraulic Universal
Tester with a 100 kN load capacity with an environmental chamber.
The load cell used for all tests also had the full 100 kN capacity.
For the test results presented below, a 0.020'' (0.51 mm) extrusion
gap (e) was used. Test conditions were a temperature of 290.degree.
C., with 35,000 psi applied force for time periods up to 3 h. Tests
were stopped at the specified times, and samples were
cross-sectioned to measure the extrusion length, h.sub.extr.
Results are shown in photographs in FIGS. 5 and 6, and summarized
in Table 1.
[0098] Simulated Backup Ring Extrusion Test Method-Results
[0099] The cross-linked PEEK formed according to the invention had
a much lower extrusion, and unexpectedly surpassed even standard
filled grades typically used for creep/extrusion resistance.
[0100] FIG. 7 shows a graphical representation of results of
simulated backup ring extrusion test. A summary of the extrusion
lengths at various times is included in Table 1 below. Note that
lower values are preferred for this test.
TABLE-US-00001 TABLE 1 Extrusion Extrusion Extrusion Height (mm)
Height (mm) Height (mm) Material (static) (1 hr creep) (3 hrs
creep) PEEK 1.38 1.88 3.29 30% Carbon 0.06 0.44 0.66 Filled PEEK
Cross-Linked 0.11 0.21 0.24 PEEK
[0101] Functional Product Testing
[0102] For functional testing, back-up ring samples were prepared
and tested in a unidirectional seal assembly, pressurized to 40,000
psi applied hydrostatic pressure at 450.degree. F., with an
extrusion gap of 0.010 inches. Pressure was ramped up to 40,000 psi
and held for a total pressurization of 48 hours.
[0103] For reference, a sample of 40% Carbon fiber-filled PEEK was
included as a comparative example. This backup ring was tested
under comparable conditions, but at a lower temperature and
pressure for a longer period of time (400.degree. F., 30,000 psi,
72 hrs). The extrusion gap for the carbon-filled backup ring was
approximately the same as the cross-linked PEEK samples (0.012
inches v. 0.010 inches for the cross-linked PEEK). However, the
cross-linked PEEK was unfilled. Two different levels of
cross-linking (at 22% and 17%) were used in different samples also
for comparison.
[0104] Higher levels of cross-linking were also shown to result in
lower extrusion (better performance for the 22% sample than the 17%
sample). Further, as the graphical results in FIG. 8 show the
significantly better extrusion resistance for crosslinked PEEK
relative to the carbon filled PEEK.
[0105] The carbon-filled PEEK sample showed severe cracking and
deformation after the test (see, FIG. 5), whereas the cross-linked
PEEK showed only minimal extrusion and deformation (see, FIG. 6).
See, also the PEEK sample at FIG. 5A.
[0106] In forming the samples herein, the material was injection
molded, then post-cured to complete thermal cross-linking. It could
be compression molded or extruded.
[0107] The specific materials used included a diol mixed with PEEK,
specifically a 17% by weight mixture of
(9,9'-(biphenyl-4,4'-diyl)bis(9H-fluoren-9-01)) incorporating an
optional cross-linking additive in the form of 0.75% lithium
acetate. The mixture was blended with 83% of a 5000 grade FP PEEK
in a Turbula.RTM. mixer. The powder mixture was compounded in a
HAAKE.RTM. twin screw extruder at temperatures of 390.degree. C. to
400.degree. C.
[0108] The pellets were injection molded into 0.55 in. by 2.5 in.
rods for extrusion test specimens, or tubes with an outer diameter
(OD) of 1.350 and an inner diameter (ID) 0.875 for back-up ring
specimens. Shapes were molded on an Arburg 66 Ton Model 320-C with
a 25 mm barrel. The samples were post-cured at elevated
temperatures to complete the cross-linking reaction. The rods and
backup ring specimens were machined to the required dimensions
prior to testing.
Example 2
[0109] Data concerning the glass transition temperature of several
samples was collected on an AR2000 DMA in torsional mode. Tests
were conducted in air atmosphere at a temperature ramp rate of 5
C/minute. Glass transition temperature measured using DMA is
different than the same property measured by use of a DSC as is
known to those skilled in the art. The DMA data is incorporated
below in Table 2.
TABLE-US-00002 TABLE 2 Tg onset Tg tan delta Material (.degree. C.)
(.degree. C.) PEEK 156 172 PEKEKK 173 191 17% Crosslinked PEEK 173
210 22% Crosslinked PEEK 174 225
Example 3
[0110] Additional tests were run to measure the tensile modulus,
post-yield tensile strength and compressive strength of samples of
PEKEKK, PEEK and a Crosslinked PEEK as in Example 1 at an elevated
temperature of 200.degree. C. The tensile modulus of samples
(measured in GPa) and the post-yield tensile strength at 10% strain
(measured in MPa) were evaluated using the procedure as set forth
in ASTM D638. Compressive strength was measured in accordance with
ASTM D690 (as measured in MPa) was also evaluated at the same
temperature. The results appear in Table 3 below and are
illustrated in FIG. 9.
TABLE-US-00003 TABLE 3 Tensile Post-Yield Tensile Compressive
Modulus Strength at 10% Strain Strength (GPa) (MPa) (MPa) PEEK
0.395 23.09 47.9 PEKEKK 0.56 29.5 86.7 Crosslinked 0.99 43.2 121.9
PEEK
[0111] The data demonstrates that at elevated temperatures, the
Crosslinked PEEK provided excellent mechanical properties in
comparison with the other materials noted that are used in the
art.
[0112] Creep tests were also run on these materials according to
ASTM D2990 at 260.degree. C. with a stress of 10 MPa. The creep
Modulus at 1, 3 and 7.5 hours is shown in Table 4 and the data is
further represented in the graphical relationship of percentage
strain v. time as shown in FIG. 10 and the data representation in
the chart of FIG. 11. The data show the high modulus under strain
which is upheld over time.
TABLE-US-00004 TABLE 4 Inst. Modulus at Modulus at Modulus at
Modulus 1 hour 3 hours 7.5 hours (MPa) (MPa) (MPa) (MPa) PEEK 2.76
1.87 1.78 1.70 PEKEKK 4.46 2.45 2.46 2.44 Crosslinked 4.95 4.31
4.26 4.12 PEEK
Example 4
[0113] Additional tests were made to sample electrical connectors
at high temperature and high pressure conditions using both PEK
connectors known in the art, and a cross-linked PEEK connector
using materials as described above in Example 3. The sample
connectors were measured for deflection and deformation at various
measurable distances d.sub.1, d.sub.2 and d.sub.3 along the
connectors, wherein such distances are illustrated in a sample
connector drawing in FIG. 12. Pressure was applied in the direction
of the arrow in FIG. 12 under high temperature and pressure
conditions cycled over time as shown in FIG. 13. A photo of the
connector samples after cycles at 20 ksi at 350.degree. F., 24 ksi
at 389.degree. F. and 30 ksi at 428.degree. F. are shown in FIG.
14. The deformation of the PEK samples (shown on the left side of
the photo) in comparison to the structural integrity at high
temperature and pressure of the crosslinked PEEK (on the right side
of the photo) is evident. FIG. 15 shows the change in dimension
d.sub.1 measured from the end of the connector to the body portion
where the sealing ring is located of a PEK sample at 20 ksi, and in
cross-linked PEEK samples at various elevated temperature and
pressure conditions. As shown in FIG. 15, at 30 ksi and 350.degree.
F., the cross-linked PEEK sample had less deformation than the PEK
sample at the same temperature but under even higher pressure.
[0114] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *