U.S. patent application number 10/461062 was filed with the patent office on 2004-12-16 for fuser member having platinum catalyzed addition cured silicone layer.
This patent application is currently assigned to Xerox Corporation. Invention is credited to Badesha, Santokh S., Gervasi, David J., Heeks, George J., Henry, Arnold W..
Application Number | 20040253436 10/461062 |
Document ID | / |
Family ID | 33511169 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040253436 |
Kind Code |
A1 |
Heeks, George J. ; et
al. |
December 16, 2004 |
FUSER MEMBER HAVING PLATINUM CATALYZED ADDITION CURED SILICONE
LAYER
Abstract
A fuser component useful in electrostatographic machines, having
a substrate, and thereover a silicone rubber layer having the
crosslinked product of at least one platinum catalyzed addition
curable vinyl terminated polyorganosiloxane, aluminum oxide
fillers, iron oxide fillers, a crosslinking agent, and having an
optional outer fluoroelastomer layer.
Inventors: |
Heeks, George J.;
(Rochester, NY) ; Henry, Arnold W.; (Pittsford,
NY) ; Badesha, Santokh S.; (Pittsford, NY) ;
Gervasi, David J.; (West Henrietta, NY) |
Correspondence
Address: |
PATENT DOCUMENTATION CENTER
XEROX CORPORATION
100 CLINTON AVE., SOUTH, XEROX SQUARE, 20TH FLOOR
ROCHESTER
NY
14644
US
|
Assignee: |
Xerox Corporation
|
Family ID: |
33511169 |
Appl. No.: |
10/461062 |
Filed: |
June 13, 2003 |
Current U.S.
Class: |
428/328 ;
428/447; 430/104 |
Current CPC
Class: |
Y10T 428/1393 20150115;
Y10T 428/269 20150115; Y10T 428/31663 20150401; C08K 3/22 20130101;
Y10T 428/3154 20150401; C08K 2003/2227 20130101; Y10T 428/257
20150115; G03G 15/2057 20130101; C09D 183/14 20130101; B32B 25/20
20130101; Y10T 428/1386 20150115; Y10T 428/256 20150115; C08K 3/22
20130101; C08L 83/04 20130101; C08K 2003/2265 20130101; C08K
2201/014 20130101; C08L 83/14 20130101 |
Class at
Publication: |
428/328 ;
428/447; 430/104 |
International
Class: |
B32B 009/04 |
Claims
1. A fuser member for fixing a developed image to a copy substrate
comprising: a) a substrate; and thereover b) a silicone rubber
layer comprising the crosslinked product of: i) at least one
platinum catalyzed addition curable polyorganosiloxane having the
following Formula I: 9wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5
are the same or different and are selected from the group
consisting of (CH.sub.2).sub.pCH.sub.3 wherein p is a number of
from about 0 to about 6, phenyl, and CH.sub.2CH.sub.2CF.sub.3;
R.sub.3 is selected from the group consisting of H and
(CH.sub.2).sub.pCH.sub.3 where p is a number of from about 0 to
about 6; R.sub.6 is selected from the group consisting of
CH.sub.2.dbd.CH and (CH.sub.2).sub.pCH.sub.3 where p is a number of
from about 0 to about 6; n is a number of from about 10 to about
4,000; and m is a number of from about 2 to about 4000; ii)
aluminum oxide fillers; iii) iron oxide fillers; and iv) a
crosslinking agent selected from the group consisting of
1,3,5,7-tetravinyltetramethyl cyclotetrasiloxane, tetravinylsilane,
and 1,1,3,3-tetravinyldimethyldisiloxane.
2. A fuser member in accordance with claim 1, wherein p in
(CH.sub.2).sub.pCH.sub.3 of R.sub.1, R.sub.2, R.sub.3, R.sub.4
R.sub.5, and R.sub.6 in Formula I is from about 1 to about 4.
3. CANCELLED
4. CANCELLED
5. A fuser member in accordance with claim 23, wherein p in
(CH.sub.2).sub.pCH.sub.3 of R.sub.1, R.sub.2, R.sub.3, R.sub.4
R.sub.5, and R.sub.6 in Formula II is from about 1 to about 4.
6. CANCELLED
7. A fuser member in accordance with claim 1, wherein said fuser
member further comprises an outer layer positioned on said silicone
rubber layer, wherein said outer layer comprises a
fluoroelastomer.
8. A fuser member in accordance with claim 7, wherein said
fluoroelastomer is selected from the group consisting of a)
copolymers of two of vinylidene fluoride, hexafluoropropylene and
tetrafluoroethylene; b) terpolymers of vinylidene fluoride,
hexafluoropropylene and tetrafluoroethylene; and c) tetrapolymers
of vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene
and a cure site monomer.
9. A fuser member in accordance with claim 8, wherein said
fluoroelastomer comprises about 35 weight percent of vinylidene
fluoride, about 34 weight percent of hexafluoropropylene, about 29
weight percent of tetrafluoroethylene, and about 2 weight percent
cure site monomer.
10. A fuser member in accordance with claim 1, wherein said
aluminum oxide fillers are present in an amount of from about 50 to
about 80 percent by weight of total solids.
11. A fuser member in accordance with claim 1, wherein said iron
oxide fillers are present in an amount of from about 1 to about 50
percent by weight of total solids.
12. A fuser member in accordance with claim 1, wherein said
aluminum oxide fillers comprise a silane coating.
13. A fuser member in accordance with claim 12, wherein said silane
coating is selected from the group consisting of epoxy silane,
vinyl silane, amine silane, methyltrimethoxysilane, and phenyl
silane.
14. Cancelled
15. A fuser member in accordance with claim 1, wherein said iron
oxide fillers comprise a silane coating.
16. A fuser member in accordance with claim 15, wherein said silane
coating is selected from the group consisting of epoxy silane,
vinyl silane, amine silane, methyltrimethoxysilane, and phenyl
silanes.
17. Cancelled
18. A fuser member in accordance with claim 1, wherein said
silicone rubber layer has a thickness of from about 1 mm to about
10 mm.
19. A fuser member in accordance with claim 1, wherein said
silicone rubber layer has a hardness from about 50 to about 78
Shore A.
20. A fuser member in accordance with claim 1, wherein said
silicone rubber layer has a modulus of from about 500 to about 800
psi.
21. Cancelled
22. An image forming apparatus for forming images on a recording
medium comprising: a charge-retentive surface to receive an
electrostatic latent image thereon; a development component to
apply toner to said charge-retentive surface to develop an
electrostatic latent image to form a developed image on said charge
retentive surface; a transfer film component to transfer the
developed image from said charge retentive surface to a copy
substrate; and a fusing component for fusing toner images to a
surface of said copy substrate, said fusing component comprising:
a) a substrate; and thereover b) a silicone rubber layer comprising
the crosslinked product of: i) at least one platinum catalyzed
addition curable polyorganosiloxane having the following Formula I:
10wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and are selected from the group consisting of
(CH.sub.2).sub.pCH.sub.3 wherein p is a number of from about 0 to
about 6, phenyl, and CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is selected
from the group consisting of H and (CH.sub.2).sub.pCH.sub.3 where p
is a number of from about 0 to about 6; R.sub.6 is selected from
the group consisting of CH.sub.2.dbd.CH and
(CH.sub.2).sub.pCH.sub.3 where p is a number of from about 0 to
about 6; n is a number of from about 10 to about 4,000; ii)
aluminum oxide fillers; iii) iron oxide fillers; and iv) a
crosslinking agent selected from the group consisting of
1,3,5,7-tetravinyltetramethyl cyclotetrasiloxane, tetravinylsilane,
and 1,1,3,3-tetravinyldimethyldisil- oxane.
23. A fuser member for fixing a developed image to a copy substrate
comprising: a) a substrate; and thereover b) a silicone rubber
layer comprising the crosslinked product of: i) at least one
platinum catalyzed addition curable polyorganosiloxane having the
following Formula II: 11wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5
are the same or different and are selected from the group
consisting of (CH.sub.2).sub.pCH.sub.3 wherein p is a number of
from about 0 to about 6, phenyl, and CH.sub.2CH.sub.2CF.sub.3;
R.sub.3 is selected from the group consisting of H and
(CH.sub.2).sub.pCH.sub.3 where p is a number of from about 0 to
about 6; R.sub.6 is selected from the group consisting of
CH.sub.2.dbd.CH and (CH.sub.2).sub.pCH.sub.3 where p is a number of
from about 0 to about 6; n is a number of from about 10 to about
4,000; ii) aluminum oxide fillers; iii) iron oxide fillers; iv) a
crosslinking agent selected from the group consisting of
1,3,5,7-tetravinyltetramethyl cyclotetrasiloxane, tetravinylsilane,
and 1,1,3,3-tetravinyldimethyldisiloxane.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to an imaging
apparatus and fuser components thereof for use in
electrostatographic, including digital, contact electrostatic
printing, and like apparatuses. The fuser components, including
fuser members, pressure member, donor members, external heat
member, and the like, are useful for many purposes including, in
the case of a fuser member, fixing a toner image to a copy
substrate. More specifically, the present invention relates to
fuser components comprising a platinum catalyzed addition cured
silicone layer. In embodiments, the silicone layer is positioned on
a substrate, which may be of many configurations including a
roller, belt, film, or like substrate. In other embodiments, the
silicone rubber layer has an outer layer thereon. In embodiments,
there is positioned between the substrate and the silicone layer,
and/or between the silicone layer and the outer layer, an
intermediate and/or adhesive layer. The present invention may be
useful as fuser members in xerographic machines, including color
machines.
[0002] In a typical electrostatographic reproducing apparatus, a
light image of an original to be copied is recorded in the form of
an electrostatic latent image upon a photosensitive member and the
latent image is subsequently rendered visible by the application of
electroscopic thermoplastic resin particles which are commonly
referred to as toner. The visible toner image is then in a loose
powdered form and can be easily disturbed or destroyed. The toner
image is usually fixed or fused upon a support, which may be the
photosensitive member itself, or other support sheet such as plain
paper.
[0003] The use of thermal energy for fixing toner images onto a
support member is well known and methods include providing the
application of heat and pressure substantially concurrently by
various means, a roll pair maintained in pressure contact, a belt
member in pressure contact with a roll, a belt member in pressure
contact with a heater, and the like. Heat may be applied by heating
one or both of the rolls, plate members, or belt members. With a
fixing apparatus using a thin film in pressure contact with a
heater, the electric power consumption is small, and the warming-up
period is significantly reduced or eliminated.
[0004] It is important in the fusing process that minimal or no
offset of the toner particles from the support to the fuser member
take place during normal operations. Toner particles offset onto
the fuser member may subsequently transfer to other parts of the
machine or onto the support in subsequent copying cycles, thus
increasing the background or interfering with the material being
copied there. The referred to "hot offset" occurs when the
temperature of the toner is increased to a point where the toner
particles liquefy and a splitting of the molten toner takes place
during the fusing operation with a portion remaining on the fuser
member. The hot offset temperature or degradation of the hot offset
temperature is a measure of the release property of the fuser, and
accordingly it is desired to provide a fusing surface, which has a
low surface energy to provide the necessary release. To ensure and
maintain good release properties of the fuser, it has become
customary to apply release agents to the fuser roll during the
fusing operation. Typically, these materials are applied as thin
films of, for example, silicone oils to prevent toner offset.
[0005] Another important method for reducing offset, is to impart
antistatic and/or field assisted toner transfer properties to the
fuser. However, to control the electrical conductivity of the
release layer, the conformability and low surface energy properties
of the release layer are often affected.
[0006] U.S. Pat. No. 4,711,818 teaches a fuser member having as a
layer, a crosslinked product of a mixture of at least one
polyfluoroorganosiloxane- , filler, heat stabilizer, crosslinking
agent and crosslinking catalyst.
[0007] U.S. Pat. No. 4,659,621 teaches a one-layer platinum
catalyzed addition cured silicone layer as a coating on a donor
roller for an electrostatographic machine.
[0008] U.S. Pat. No. 4,763,158 teaches a fuser member having as a
layer, a platinum catalyzed addition cured silicone material.
[0009] U.S. Pat. No. 4,777,087 teaches a platinum catalyzed
addition cured polyorganosiloxane useful as layers in a fuser
member for an electrostatographic apparatus.
[0010] U.S. Pat. No. 4,868,251 teaches an ultraviolet light
absorbing silicone composition. A platinum catalyzed vinyl/hydride
addition cured silicone material can be used in crosslinking. The
silicone material can be used in lenses.
[0011] U.S. Pat. No. 4,925,895 teaches a polyorganosiloxane
platinum catalyzed addition curable silicone elastomer useful as a
layer for a fuser member useful in xerographic machines.
[0012] U.S. Pat. No. 4,983,641 teaches a platinum-catalyzed
addition cured silicone foamable composition.
[0013] U.S. Pat. No. 5,082,871 teaches a platinum catalyzed
addition curable polyorganosiloxane release coating
composition.
[0014] U.S. Pat. No. 5,164,462 teaches an ultraviolet light
absorbing silicone elastomer that is crosslinked using a
platinum-catalyzed addition cured silicone material. The silicone
materials may be useful in lenses.
[0015] U.S. Pat. No. 5,217,837 teaches a peroxide cured silicone
elastomer layer for a fuser member.
[0016] U.S. Pat. No. 5,352,753 teaches an ultraviolet light
absorbing silicone layer with filler. The silicone may be formed
with a crosslinking agent that is a platinum catalyzed addition
cured silicone. An amino siloxane is disclosed as a crosslinking
agent. The coating is useful as a lens material.
[0017] U.S. Pat. No. 5,401,570 teaches a fuser member comprising a
substrate and thereover, a silicone rubber containing a filler. The
silicone elastomer can be peroxide cured.
[0018] U.S. Pat. No. 5,464,896 teaches an addition cured silicone
layer with fluorocarbon outer surface as coatings for fuser
members.
[0019] U.S. Pat. No. 5,466,768 teaches an ultraviolet light
absorbing silicone layer with filler. The silicone may be formed
with a crosslinking agent that is a platinum catalyzed addition
cured silicone. An amino siloxane is disclosed as a crosslinking
agent. The coating is useful as a lens material.
[0020] U.S. Pat. No. 5,474,821 teaches a fuser member having a
layer of platinum catalyzed addition cured silicone material.
[0021] Known fuser coatings include high temperature polymers such
as polytetrafluoroethylene, perfluoroalkoxy, fluorinated ethylene
propylene, silicone rubber, fluorosilicone rubber,
fluoroelastomers, and the like. These coatings have been found to
have adequate release properties and control toner offset
sufficiently. However, problems have resulted with known fuser
member layers, including that the fuser member prematurely hardens
resulting in a life short fall. Some known fuser members have also
been shown to show a susceptibility to contamination, scratching
and other damage. Further, silicone rubber layers tend to swell
upon application of release agents. Moreover, fuser members have
been shown to provide toner offset or inferior release capability,
which allows for inappropriate copies and/or prints, and toner
contamination to other parts of the machine.
[0022] In order to solve some of the above problems, a boron
nitride filler has been introduced into a silicone rubber to
provide a superior layer material. However, use of boron nitride is
expensive and has been found not to solve all the above
problems.
[0023] A platinum catalyzed addition cured silicone layer as a
layer for fuser members has been shown to correct some, if not all,
of the above problems. For example, the layer improves delivery and
processability. However, the layer is not thermally conductive or
thermally stable.
[0024] Therefore, a need remains for fuser components for use in
electrostatographic machines that have superior mechanical
properties, including the ability to maintain superior heat age
stability, and consequently, improved life short fall. A further
need remains for fuser coatings having increased toughness and
increased tensile strength, having a reduced susceptibility to
contamination, scratching, and other damage. In addition, a need
remains for a fuser component with a decreased tendency to swell in
the presence of release agents. A need further remains for a fuser
member layer, which decreases toner offset, resulting in a decrease
or elimination of inferior prints and/or copies and toner
contamination to other parts of the machine. In addition, a need
remains for a fuser member having superior thermal conductivity,
good conformability, lower modulus, and lower hardness. Further, it
is desired to dispense with the need for expensive fillers such as
boron nitride in the fuser layer(s).
SUMMARY OF THE INVENTION
[0025] The present invention provides, in embodiments, a fuser
member for fixing a developed image to a copy substrate comprising
a) a substrate; and thereover b) a silicone rubber layer comprising
the crosslinked product of i) at least one platinum catalyzed
addition curable vinyl terminated polyorganosiloxane having the
following Formula I: 1
[0026] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and are selected from the group consisting of
(CH.sub.2).sub.pCH.sub.3 wherein p is a number of from about 0 to
about 6, phenyl, and CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is selected
from the group consisting of H and (CH.sub.2).sub.pCH.sub.3 where p
is a number of from about 0 to about 6; R.sub.6 is selected from
the group consisting of CH.sub.2.dbd.CH and
(CH.sub.2).sub.pCH.sub.3 where p is a number of from about 0 to
about 6; n is a number of from about 10 to about 4,000; and m is a
number of from about 2 to about 4000; i) aluminum oxide fillers;
iii) iron oxide fillers; and iv) a crosslinking agent.
[0027] The present invention further includes, in embodiments, a
fuser member for fixing a developed image to a copy substrate
comprising: a) a substrate; and thereover b) a silicone rubber
layer comprising the crosslinked product of i) at least one
platinum-catalyzed addition curable vinyl terminated
polyorganosiloxane having the following Formula I: 2
[0028] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and are selected from the group consisting of
(CH.sub.2).sub.pCH.sub.3 wherein p is a number of from about 0 to
about 6, phenyl, and CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is selected
from the group consisting of H and (CH.sub.2).sub.pCH.sub.3 where p
is a number of from about 0 to about 6; R.sub.6 is selected from
the group consisting of CH.sub.2.dbd.CH and
(CH.sub.2).sub.pCH.sub.3 where p is a number of from about 0 to
about 6; n is a number of from about 10 to about 4,000; and m is a
number of from about 2 to about 4000; ii) aluminum oxide fillers;
iii) iron oxide fillers; and iv) a crosslinking agent; and c) an
outer layer positioned on said silicone rubber layer, wherein said
outer layer comprises a fluoroelastomer.
[0029] In addition, the present invention provides, in embodiments,
an image forming apparatus for forming images on a recording medium
comprising a charge-retentive surface to receive an electrostatic
latent image thereon; a development component to apply toner to
said charge-retentive surface to develop an electrostatic latent
image to form a developed image on said charge retentive surface; a
transfer film component to transfer the developed image from said
charge retentive surface to a copy substrate; and a fusing
component for fusing toner images to a surface of said copy
substrate, said fusing component comprising a) a substrate; and
thereover b) a silicone rubber layer comprising the crosslinked
product of i) at least one platinum catalyzed addition curable
vinyl terminated polyorganosiloxane having the following Formula I:
3
[0030] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and are selected from the group consisting of
(CH.sub.2).sub.pCH.sub.3 wherein p is a number of from about 0 to
about 6, phenyl, and CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is selected
from the group consisting of H and (CH.sub.2).sub.pCH.sub.3 where p
is a number of from about 0 to about 6; R.sub.6 is selected from
the group consisting of CH.sub.2.dbd.CH and
(CH.sub.2).sub.pCH.sub.3 where p is a number of from about 0 to
about 6; n is a number of from about 10 to about 4,000; and m is a
number of from about 2 to about 4000; ii) aluminum oxide fillers;
iii) iron oxide fillers; and iv) a crosslinking agent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The above embodiments of the present invention will become
apparent as the following description proceeds upon reference to
the drawings, which include the following figures:
[0032] FIG. 1 is an illustration of a general electrostatographic
apparatus.
[0033] FIG. 2 is a sectional view of a fusing belt in accordance
with one embodiment of the present invention.
[0034] FIG. 3 is a schematic illustration of an embodiment of the
present invention, and represents a fuser component having a
two-layer configuration, wherein the silicone layer is the outer
layer.
[0035] FIG. 4 is an illustration of an embodiment of the present
invention, and represents a fuser component having a three-layer
configuration, wherein the silicone layer is the intermediate
layer.
[0036] FIG. 5 is a graph showing hardness versus hours at a certain
temperature for an embodiment of a platinum catalyzed addition
curable vinyl terminated polyorganosiloxane layer.
[0037] FIG. 6 is a graph of modulus versus hours at a certain
temperature for an embodiment of a platinum catalyzed addition
curable vinyl terminated polyorganosiloxane layer.
[0038] FIG. 7 is a graph showing modulus versus hours at
215.5.degree. C. in an oven for an embodiment of a platinum
catalyzed addition curable vinyl terminated polyorganosiloxane
layer.
[0039] FIG. 8 is a graph of modulus versus hours at 405.degree. F.
for a platinum catalyzed addition curable vinyl terminated
polyorganosiloxane (DC-6395) and the leading HTV (high temperature
vulcanized silicone rubber) from Ames.
DETAILED DESCRIPTION OF THE INVENTION
[0040] The present invention is directed to fuser components, and
in particular, fusing components including fuser members; pressure
members; donor members such as release agent donor members, release
agent metering members, and the like; transfix or transfuse
members; external heat members; and the like. In an embodiment of
the present invention, the fuser component comprises a substrate
and a layer comprising a platinum catalyzed addition cured silicone
rubber. In another embodiment, the fuser component comprises a
substrate having an intermediate layer comprising a platinum
catalyzed addition cured silicone rubber thereon, and having an
outer layer on the silicone intermediate layer. In embodiments,
optional adhesive and/or intermediate layers can be present between
the substrate and the silicone layer, and/or between the silicone
intermediate layer and the outer release layer. In embodiments, the
silicone layer contains aluminum oxide and iron oxide fillers
dispersed or contained therein.
[0041] The present silicone rubber layer has been shown, in
embodiments, to have superior mechanical properties, including the
ability to maintain superior heat age stability, and consequently,
improved life short fall. The silicone rubber fuser coatings, in
embodiments, have increased toughness and increased tensile
strength, and have a reduced susceptibility to contamination,
scratching, and other damage. In addition, the silicone rubber
fuser layer, in embodiments, has a decreased tendency to swell in
the presence of release agents. The silicone rubber fuser member
layer, in embodiments, also decreases toner offset, resulting in a
decrease or elimination of inferior prints and/or copies and toner
contamination to other parts of the machine. In addition, in
embodiments, the silicone rubber fuser member layer exhibits
superior thermal conductivity, good conformability, lower modulus,
and lower hardness. Further, with the silicone rubber layer, in
embodiments, there is no need for expensive fillers such as boron
nitride.
[0042] Referring to FIG. 1, in a typical electrostatographic
reproducing apparatus, a light image of an original to be copied is
recorded in the form of an electrostatic latent image upon a
photosensitive member and the latent image is subsequently rendered
visible by the application of electroscopic thermoplastic resin
particles which are commonly referred to as toner. Specifically,
photoreceptor 10 is charged on its surface by means of a charger 12
to which a voltage has been supplied from power supply 11. The
photoreceptor is then imagewise exposed to light from an optical
system or an image input apparatus 13, such as a laser and light
emitting diode, to form an electrostatic latent image thereon.
Generally, the electrostatic latent image is developed by bringing
a developer mixture from developer station 14 into contact
therewith. Development can be effected by use of a magnetic brush,
powder cloud, or other known development process.
[0043] After the toner particles have been deposited on the
photoconductive surface, in image configuration, they are
transferred to a copy sheet 16 by transfer means 15, which can be
pressure transfer or electrostatic transfer. Alternatively, the
developed image can be transferred to an intermediate transfer
member and subsequently transferred to a copy sheet.
[0044] After the transfer of the developed image is completed, copy
sheet 16 advances to fusing station 19, depicted in FIG. 1 as
fusing and pressure rolls, wherein the developed image is fused to
copy sheet 16 by passing copy sheet 16 between the fusing member 20
and pressure member 21, thereby forming a permanent image.
Photoreceptor 10, subsequent to transfer, advances to cleaning
station 17, wherein any toner left on photoreceptor 10 is cleaned
therefrom by use of a blade 22 (as shown in FIG. 1), brush, or
other cleaning apparatus. Although the fusing station 19 depicts
the fusing and pressure members as rollers, the fuser and/or
pressure member(s) may also be in the form of belts, sheets, films
or other like fusing members.
[0045] Referring to FIG. 2, an embodiment of a fusing station 19 is
depicted with an embodiment of a fuser roll 20 comprising polymer
surface 5 upon a suitable base member 4, a hollow cylinder or core
fabricated from any suitable metal, such as aluminum, anodized
aluminum, steel, nickel, copper, and the like, having a suitable
heating element 6 disposed in the hollow portion thereof which is
coextensive with the cylinder. The fuser member 20 can include an
adhesive, cushion, or other suitable layer 7 positioned between
core 4 and outer layer 5. Backup or pressure roll 21 cooperates
with fuser roll 20 to form a nip or contact arc 1 through which a
copy paper or other substrate 16 passes such that toner images 24
thereon contact elastomer surface 5 of fuser roll 20. As shown in
FIG. 2, an embodiment of a backup roll or pressure roll 21 is
depicted as having a rigid steel core 2 with a polymer or elastomer
surface or layer 3 thereon. Sump 25 contains polymeric release
agent 26 that may be a solid or liquid at room temperature, but it
is a fluid at operating temperatures. The pressure member 21 may
include a heating element (not shown).
[0046] In the embodiment shown in FIG. 2 for applying the polymeric
release agent 26 to polymer or elastomer surface 5, two release
agent delivery rolls 27 and 28 rotatably mounted in the direction
indicated are provided to transport release agent 26 to polymer or
elastomer surface 5. Delivery roll 27 is partly immersed in the
sump 25 and transports on its surface release agent from the sump
to the delivery roll 28. By using a metering blade 29, a layer of
polymeric release fluid can be applied initially to delivery roll
27 and subsequently to polymer or elastomer 5 in controlled
thickness ranging from submicrometer thickness to thicknesses of
several micrometers of release fluid. Thus, by metering device 29,
preferably from about 0.1 to about 2 micrometers or greater
thicknesses of release fluid can be applied to the surface of
polymer or elastomer 5.
[0047] The fusing component of the present invention can be
comprised of at least two different configurations. In one
embodiment of the invention, the fusing component is of a two-layer
configuration as shown in FIG. 3. FIG. 3 demonstrates fusing
component as fuser belt 39. However, it is understood that this and
other configurations herein such as a fuser roller, can be used as
the fusing member. Fuser member 39 comprises substrate 30 having
optional fillers 31 dispersed or contained therein. Positioned over
the substrate is outer silicone rubber layer 32 having optional
fillers 35 dispersed or contained therein.
[0048] FIG. 4 demonstrates an alternative embodiment of the fuser
member 39, which is that of a three-layer configuration. FIG. 4
demonstrates substrate 30 having optional fillers 31 dispersed or
contained therein. Positioned on the substrate 30 is intermediate
silicone layer 32 having optional fillers 35 dispersed or contained
therein. Positioned over the intermediate silicone layer 32 is
outer release layer 33 having optional fillers 36 dispersed or
contained therein.
[0049] An adhesive layer, or other intermediate layer or layers may
be present between the substrate and the silicone intermediate
layer. Fillers 31, 35, and 36 are optional, and if present, may be
the same or different.
[0050] Examples of suitable substrate materials include in the case
of roller or film-type substrates, metals such as aluminum,
stainless steel, steel, nickel and the like. In the case of
film-type substrates, suitable substrates include high temperature
plastics that are suitable for allowing a high operating
temperature (i.e., greater than about 80 C., preferably greater
than 200.degree. C.), and capable of exhibiting high mechanical
strength. In embodiments, the plastic has a flexural strength of
from about 2,000,000 to about 3,000,000 psi, and a flexural modulus
of from about 25,000 to about 55,000 psi. Plastics possessing the
above characteristics and which are suitable for use as the
substrate for the fuser members include epoxy; polyphenylene
sulfide such as that sold under the tradenames FORTRON.RTM.
available from Hoechst Celanese, RYTON R-4.RTM. available from
Phillips Petroleum, and SUPEC.RTM. available from General Electric;
polyimides such as polyamideimide sold under the tradename
TORLON.RTM. 7130 available from Amoco; polyketones such as those
sold under the tradename KADEL.RTM. E1230 available from Amoco,
polyether ether ketone sold under the tradename PEEK 450GL30 from
Victrex, polyaryletherketone, and the like; polyamides such as
polyphthalamide sold under the tradename AMODEL.RTM. available from
Amoco; polyethers such as polyethersulfone, polyetherimide,
polyaryletherketone, and the like; polyparabanic acid; and the
like; liquid crystalline resin (XYDAR.RTM.) available from Amoco;
ULTEM.RTM. available from General Electric; ULTRAPEK.RTM. available
from BASF; and the like, and mixtures thereof. Other suitable
substrate materials include fluoroelastomers such as those sold
under the tradename VITON.RTM. from DuPont; silicone rubbers, and
other elastomeric materials. The substrate may also comprise a
mixture of any of the above materials. In embodiments, the
substrate comprises aluminum.
[0051] The substrate as a film, sheet, belt, or the like, has a
thickness of from about 25 to about 250, or from about 60 to about
100 micrometers.
[0052] Over the substrate is the platinum catalyzed addition cured
silicone layer. The silicone layer may be positioned over an
adhesive, primer or other layer. The silicone layer may be cured
using addition-curing techniques. These addition-curing techniques
include two-component systems, and one-component systems. The
one-component system can be used if the catalyst is inhibited
sufficiently. These systems may be made by adding a polyfunctional
silicon hydride crosslinker to a vinyl-containing silicone polymer.
Vinyl on the end of the polymer is more reactive than vinyl in the
chain. The catalyst is usually a complex of platinum, although
palladium, rhodium and ruthenium can also be used. The following
reaction demonstrates an addition cured technique. 4
[0053] In the above system, there are no volatile by-products. The
compounds have excellent resistance to compression set and to
reversion. Elastomers produced have demonstrated increased
toughness, tensile strength and dimensional stability. Both
terminal and internal vinyl groups may be cured by this method,
although the former usually leads to greater toughness.
[0054] The amount of platinum used can be from about 1 to about 25
ppm, or from about 5 to about 10 ppm. The starting products are
used in ratio of from about 20:0.5 to about 10:0.5, or from about
10:1 to about 10:2. by weight of --SiH-- to
CH.sub.2.dbd.CH.sub.2Si. The stoichiometry of the hydride to the
vinyl components can be from about 1:1 to about 10:1, or about 1:1
to about 6:1.
[0055] The silicone elastomer layer comprises a two-component
platinum catalyzable addition cured silicone rubber formed by the
reaction below: 5
[0056] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and can be (CH.sub.2).sub.pCH.sub.3 where p is a number
of from about 0 to about 6, or from about 1 to about 4, phenyl, or
CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is H, (CH.sub.2).sub.pCH.sub.3
where p is a number of from about 0 to about 6, or from about 1 to
about 4; R.sub.6 is CH.sub.2.dbd.CH or (CH.sub.2).sub.pCH.sub.3
where p is a number of from about 0 to about 6, or from about 1 to
about 4; n is a number of from about 10 to about 4,000; and m is a
number of from about 2 to about 4000. The product above is the
following Formula I: 6
[0057] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and can be (CH.sub.2).sub.pCH.sub.3 where p is a number
of from about 0 to about 6, or from about 1 to about 4, phenyl, or
CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is H, (CH.sub.2).sub.pCH.sub.3
where p is a number of from about 0 to about 6, or from about 1 to
about 4; R.sub.6 is CH.sub.2.dbd.CH or (CH.sub.2).sub.pCH.sub.3
where p is a number of from about 0 to about 6, or from about 1 to
about 4; n is a number of from about 10 to about 4,000; and m is a
number of from about 2 to about 4000.
[0058] In an embodiment, the silicone material is
divinyl-terminated. A specific example of a divinyl-terminated
platinum catalyzed addition cured silicone material is formed by
the reaction below: 7
[0059] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and can be (CH.sub.2).sub.pCH.sub.3 where p is a number
of from about 0 to about 6, or from about 1 to about 4, phenyl, or
CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is H or (CH.sub.2).sub.pCH.sub.3
where p is a number of from about 0 to about 6, or from about 1 to
about 4; R.sub.6 is CH.sub.2.dbd.CH, (CH.sub.2).sub.pCH.sub.3 where
p is a number of from about 0 to about 6, or from about 1 to about
4; n is a number of from about 10 to about 4,000; and m is a number
of from about 2 to about 4000. The product above is the following
Formula II: 8
[0060] wherein R.sub.1, R.sub.2, R.sub.4, R.sub.5 are the same or
different and can be (CH.sub.2).sub.pCH.sub.3 where p is a number
of from about 0 to about 6, or from about 1 to about 4, phenyl, or
CH.sub.2CH.sub.2CF.sub.3; R.sub.3 is H, or (CH.sub.2).sub.pCH.sub.3
where p is a number of from about 0 to about 6, or from about 1 to
about 4; R.sub.6 is CH.sub.2.dbd.CH, (CH.sub.2).sub.pCH.sub.3 where
p is a number of from about 0 to about 6, or from about 1 to about
4; n is a number of from about 10 to about 4,000; and m is a number
of from about 2 to about 4000.
[0061] Commercially available platinum-catalyzed addition cured
silicone rubbers include those available from Dow Corning, such as
the silicone rubber sold under the designation DC3-6395 (one-part
formulation) and DC3-6396 (two-part formulation).
[0062] The platinum-catalyzed addition cured silicone rubber can be
prepared by the above process using platinum as a catalyst, along
with a crosslinking agent. Suitable crosslinking agents include
silanes such as 1,3,5,7-tetravinyltetramethyl cyclotetrasiloxane
(T2160 available from United Chemical Technologies, Pennsylvania),
tetravinylsilane (T2150 from UCT),
1,1,3,3-tetravinyldimethyldisiloxane (T2145 from UCT), and the
like. The crosslinking agent is used to process the platinum
catalyzed addition cured silicone in an amount of from about 0.5 to
about 10 pph, or from about 2 to about 8 pph.
[0063] A low surface energy filler and/or electrically conductive
filler and/or chemically reactive filler may be present in the
silicone layer, the substrate, the intermediate layer(s), and/or
the outer release layer. The filler if present in the outermost
layer may aid in release by reacting with any functional groups in
any release agent present. The electrically conductive filler may
aid in controlling the charge on the fuser member to enhance
performance such as non-visual offset or pre-nip toner disturbances
or to enable use as a transfix or transfuse member.
[0064] Examples of suitable fillers include carbon fillers, metals,
metal oxides, doped metal oxides, ceramics, polymer fillers, and
the like, and mixtures thereof. Nanofillers are also suitable for
use herein, including those having particle sizes of from about
from 5 to about 350 nanometers, or from about 20 to about 100
nanometers. Examples of suitable carbon fillers include carbon
black (for example, N330.RTM. from Cabot, Alpharetta, Ga.)
graphite, fluorinated carbon black (for example, ACCUFLUOR.RTM. or
CARBOFLUOR.RTM.), and the like, and mixtures thereof. Examples of
metal fillers include aluminum, copper, silver, and the like, and
mixtures thereof. Examples of suitable inorganics/ceramics include
silica, silicon carbide, silicone nitride, boron nitride, aluminum
nitride, boron carbide, tungsten carbide, calcium carbonate, clay,
and the like, and mixtures thereof. Examples of suitable metal
oxides include copper oxide, aluminum oxide, zinc oxide, titanium
oxide, iron oxide, and the like, and mixtures thereof. Examples of
suitable doped metal oxides include antimony doped tin oxide (such
as ZELEC.RTM., which is a trademark of DuPont Chemicals Jackson
Laboratories, Deepwater, N.J.), aluminum doped zinc oxide, antimony
doped titanium dioxide, similar doped oxides, and mixtures thereof.
Examples of suitable polymer fillers include polyaniline,
polytetrafluoroethylene powder, perfluoroalkoxy powder, ethylene
chlorotrifluoroethylene, ethylene tetrafluoroethylene,
polytetrafluoroethylene perfluoromethylvinylether copolymer,
fluorinated ethylene propylene powder, and the like, and mixtures
thereof.
[0065] In an embodiment, aluminum oxide filler and/or iron oxide
filler are incorporated into the silicone elastomer layer. The
aluminum oxide filler can be provided in an amount from about 50 to
about 80, or from about 60 to about 75 percent by weight of total
solids. The iron oxide filler can be present in an amount from
about 1 to about 50, or from about 10 to about 20 percent by weight
of total solids. Total solids, as used herein, refers to the total
amount by weight of silicone rubber, fillers, crosslinking agents,
and other like solid materials.
[0066] In an embodiment, the filler or fillers can be coated with a
silane material. This silane lowers the surface energy of the
silicone elastomer layer as well as improves particle separation
and particle flow. In embodiments, the silane coating reduces
particle agglomeration, thus allowing more uniform particle
distribution, reduced settling, and free movement of individual
particles during processing. Examples of suitable silanes for
coating filler(s) include, but are not limited to epoxy, vinyl,
amine, phenyl, and other functional silanes, mixtures thereof, and
the like. In an embodiment, the silane coating is
methyltrimethoxysilane (CH.sub.3O).sub.3SiCH.sub.3. The amount of
silane incorporated with the filler into the above-identified
silicone elastomer is an amount sufficient to increase thermal
stability of the silicone elastomer to repeated exposure to fusing
temperatures, pressures and other fusing conditions. The silane is
coated on the filler by known coupling methods.
[0067] The silicone elastomer may be spray coated, molded, flow
coated, or the like, onto the substrate, or onto the optional
primer, adhesive, or intermediate layer according to known
procedures.
[0068] The thickness of the silicone elastomer layer is from about
1 mm to about 10 mm, or from about 3 mm to about 7 mm, or from
about 4 mm to about 6 mm. The above-identified silicone elastomer
layer has a hardness of from about 50 to about 78, or from about 55
to about 75, or from about 60 to about 65 Shore A. The thermal
conductivity is from about 1.times.10.sup.-7 to about
1.times.10.sup.-1, or about 1.5.times.10.sup.-3. The toughness is
from about 250 to about 450, or from about 350 to about 380
lb/in.sup.3. The modulus is from about 500 to about 800 psi.
[0069] Optionally, an outer release layer may be coated on the
silicone layer using known techniques such as spray coating, dip
coating, flow coating, or the like. In embodiments, an outer
fluoroelastomer layer can be present on the silicone layer, or on
an adhesive, primer or other intermediate layer positioned between
the silicone material layer and the outer fluoroelastomer
layer.
[0070] Examples of suitable fluoroelastomers include copolymers and
terpolymers of vinylidenefluoride, hexafluoropropylene and
tetrafluoroethylene, which are known commercially under various
designations as VITON A.RTM., VITON E.RTM., VITON E60C.RTM., VITON
E45.RTM., VITON E430.RTM., VITON 910.RTM., VITON GH.RTM., VITON
B50.RTM., and VITON GF.RTM.. The VITON.RTM. designation is a
Trademark of E.I. DuPont de Nemours, Inc. Other commercially
available materials include FLUOREL 2170.RTM., FLUOREL 2174.RTM.,
FLUOREL 2176.RTM., FLUOREL 2177.RTM. and FLUOREL LVS 76.RTM.
FLUOREL.RTM. being a Trademark of 3M Company. Additional
commercially available materials include AFLAS.TM. a
poly(propylene-tetrafluoroethylene) and FLUOREL II.RTM. (LII900) a
poly(propylene-tetrafluoroethylene vinylidenefluoride) both also
available from 3M Company, as well as the Tecnoflons identified as
FOR-60KIR.RTM., FOR-LHF.RTM., NM.RTM. FOR-THF.RTM., FOR-TFS.RTM.,
TH.RTM., TN505.RTM. available from Montedison Specialty Chemical
Company.
[0071] Two specific known fluoroelastomers are (1) a class of
copolymers of one or more of, or any combination of
vinylidenefluoride, tetrafluoroethylene and hexafluoropropylene
known commercially as VITON A.RTM. and (2) a class of terpolymers
of vinylidenefluoride, hexafluoropropylene, and tetrafluoroethylene
known commercially as VITON B.RTM.. VITON A.RTM., and VITON B.RTM.,
and other VITON.RTM. designations are trademarks of E.I. DuPont de
Nemours and Company.
[0072] In another embodiment, the fluoroelastomer is a tetrapolymer
having a relatively low quantity of vinylidenefluoride. An example
is VITON GF.RTM., available from E.I. DuPont de Nemours, Inc. The
VITON GF.RTM. has about 35 weight percent of vinylidenefluoride,
about 34 weight percent of hexafluoropropylene and about 29 weight
percent of tetrafluoroethylene with about 2 weight percent cure
site monomer. The cure site monomer can be those available from
DuPont such as 4-bromoperfluorobutene-1,
1,1-dihydro-4-bromoperfluorobutene-1, 3-bromoperfluoropropene-1,
1,1-dihydro-3-bromoperfluoropropene-1, or any other suitable,
known, commercially available cure site monomer.
[0073] In another embodiment, the fluoroelastomer is a volume
grafted elastomer. Volume grafted elastomers are a special form of
hydrofluoroelastomer and are substantially uniform integral
interpenetrating networks of a hybrid composition of a
fluoroelastomer and a polyorganosiloxane, the volume graft having
been formed by dehydrofluorination of fluoroelastomer by a
nucleophilic dehydrofluorinating agent, followed by addition
polymerization by the addition of an alkene or alkyne functionally
terminated polyorganosiloxane and a polymerization initiator.
[0074] Volume graft, in embodiments, refers to a substantially
uniform integral interpenetrating network of a hybrid composition,
wherein both the structure and the composition of the
fluoroelastomer and polyorganosiloxane are substantially uniform
when taken through different slices of the fuser member. A volume
grafted elastomer is a hybrid composition of fluoroelastomer and
polyorganosiloxane formed by dehydrofluorination of fluoroelastomer
by nucleophilic dehydrofluorinating agent followed by addition
polymerization by the addition of alkene or alkyne functionally
terminated polyorganosiloxane. Examples of specific volume graft
elastomers are disclosed in U.S. Pat. No. 5,166,031; U.S. Pat. No.
5,281,506; U.S. Pat. No. 5,366,772; and U.S. Pat. No. 5,370,931,
the disclosures of which are herein incorporated by reference in
their entirety.
[0075] The outer release layer can be coated on the silicone layer
or on an adhesive, primer or other intermediate layer, to a
thickness of from about 10 to about 65, or from about 15 to about
40 .mu.m, in the case of a fuser roller. For a belt fusing
component, the thickness of the outer release layer is from about 2
to about 7, or from about 3 to about 4 mm.
[0076] The fusing component can be of any suitable configuration.
Examples of suitable configurations include a sheet, a film, a web,
a foil, a strip, a coil, a cylinder, a drum, a roller, an endless
strip, a circular disc, a belt including an endless belt, an
endless seamed flexible belt, an endless seamless flexible belt, an
endless belt having a puzzle cut seam, and the like.
[0077] Optionally, any known and available suitable adhesive,
primer or intermediate layer may be positioned between the silicone
layer and the substrate, and/or between the silicone layer and the
outer release layer. Examples of suitable adhesives include silanes
such as amino silanes (such as, for example, A1100 from OSI
Specialties, Friendly West Virginia), titanates, zirconates,
aluminates, and the like, and mixtures thereof. In an embodiment,
an adhesive in from about 0.25 to about 10 percent solution, can be
wiped on the substrate. The adhesive layer can be coated on the
substrate, or on the silicone layer, to a thickness of from about 2
to about 2,000 nanometers, or from about 2 to about 500 nanometers.
The adhesive can be coated by any suitable, known technique,
including spray coating or wiping.
[0078] Specific embodiments of the invention will now be described
in detail. These examples are intended to be illustrative, and the
invention is not limited to the materials, conditions, or process
parameters set forth in these embodiments. All parts are
percentages by volume of total solids unless otherwise
indicated.
EXAMPLES
Example 1
Stability Testing of Platinum Catalyzed Addition Cured Silicone
Rubber
[0079] A platinum catalyzed addition cured silicone rubber
(DC3-6395) was purchased from Dow Corning. The silicone rubber was
processed by adding a crosslinker (a vinyl functional siloxane
coupled with a platinum catalyst). The rubber filler content and
crosslinker content were varied in uniform increments in order to
determine stability of fuser member over time. The samples were
evaluated for Shore A hardness changes over time. The length of
time ranged up to 8 weeks and the temperature was 204.degree. C. in
a flow through oven.
[0080] Expressions showing a variation of both the hardness and the
thermal conductivity with only concentration changes was determined
and is shown in the first two equations below. An estimate of the
relationship between hardness change with both concentration and
age time is expressed by the third equation. The regression
expressions below were derived from the experimental data using a
plus one and a minus one to represent the high/low concentrations
levels and the initial/aged values of the independent variables,
i.e., the filler and crosslinker concentration levels as well as
the oven age time. Hardness is expressed as Shore A and Thermal
Conductivity as W/Msec. The variables are identified below.
[0081] A=Filler level, B=crosslinker level and C=oven age time
Hardness (time zero)=4.5A+3.25B=2.25BC
Thermal Conductivity (time zero)=0.09A-0.01B+0.70
Hardness=4.25A+3.25B+8.5C+2.25BC+77
[0082] The minus-value for both the filler level and the
crosslinker level represent the standard formulation of the
DC3-6395 and is called Formula 1. The BC interaction in the third
equation suggests that the lower level of crosslinker may have a
beneficial influence by keeping the hardness increase less
pronounced during aging.
Example 2
Physical Analysis of Molded Test Parts
[0083] The above-identified silicone elastomer composition exhibits
superior heat age stability as measured by initial rubber property
values and changes in these properties as the pads or rolls were
oven/fixture tested. The initial, non-age rubber properties were
used to screen other candidate materials and discard unacceptable
rubbers before the age test began. Two important initial properties
were hardness and thermal conductivity, wherein the acceptable
candidate was required to have the highest thermal conductivity at
the required hardness. Table I below displays some candidate
silicone rubbers and the initial test results. Standard hardness
and thermal conductivity testing was performed.
1TABLE I Thermal Conductivity Candidate Rubber Shore A Hardness
W/Msec DC 6395 Pt catalyzed 63 (Required Hardness) 0.62 DC 591 Pt
catalyzed 70 0.40 ECD LEW 64 0.56 Condensation Crosslinked Sn
catalyzed DC 437 HTV at 170 66 0.53 Parts Al.sub.2O.sub.3 peroxide
catalyzed X 727 Sn catalyzed (51 measured) (0.33 measured) 51* for
6395 0.36* for 6395
[0084] Measured data for the X727 (a boron nitride filled silicone
rubber described in U.S. Pat. No. 4,763,158) is shown along with
calculated data for the DC6395, where the regression equations were
used to obtain the thermal conductivity at the hardness of the
X727. Note that this is only an estimate, especially since the
hardness levels calculated were outside the design range of the
statistical experiment. The hardness calculated data compared very
favorably to the measured data for all treatment combinations in
the statistical designed experiment.
Example 3
Demonstration Example of Test Pads and Rolls
[0085] Another sample of DC 6395 was purchased from Dow Corning,
and was tested by coating test rolls and then aging the rollers in
ovens and on fixtures. Test pads were also oven aged and the Shore
A hardness ratio (aged hardness/initial hardness) was plotted and
compared to curves of the modulus change found in similar rolls
that were oven and fixture tested.
[0086] The graphs of FIGS. 5 and 6 illustrate that although the DC
6395 is temperature stable for an extended period, fixture
compaction may eventually be a failure mode, so it was tested
separately.
[0087] A graph as shown in FIG. 7 compares the DC 6395 to other
candidates. Once again, the DC 6395 shows desired results,
including a minimum modulus change with oven age time, thus
remaining within the required functional modulus range of 500 to
800 psi. Candidate fuser rolls were oven-aged at 212.5.degree. C.
for about 3,000 hours. As shown in the graph, the 6396 remains
stable with respect to modulus over the tested time frame.
Example 4
Demonstration Example of Test Pads and Rolls
[0088] Two representative test rolls were prepared according to
their respective or anticipated roll coating procedures. One was a
vendor coated HTV and the other was DC6395. Data for the DC 6395
and the leading HTV silicone rubber contender was taken from a
fixture test that was designed to be somewhat similar to the
expected application. The two Modulus (PSI) versus Hours in Fixture
curves are displayed in the graphs of FIG. 8. The curves give a
clear demonstration that a minimal change in modulus was observed
with the DC6395, while the other candidate, an HTV, was shown to be
unacceptable.
[0089] While the invention has been described in detail with
reference to specific and preferred embodiments, it will be
appreciated that various modifications and variations will be
apparent to the artisan. All such modifications and embodiments as
may readily occur to one skilled in the art are intended to be
within the scope of the appended claims.
* * * * *