Note: Descriptions are shown in the official language in which they were submitted.
13~ 5
ROLL COVERED WITH SILICONE MATERIAL
AND METHOD FOR PRODUCING ~AME
Thi~ invention relate~ to a roll covered with a
silicone materia~ ~uitable for the variouæ applications,
including transfer rolls, heating roll~, pressure rolls,
and ~leaning roll~, typically found in
electrophotographic copier~ and facsimlle devices. More
par~icularly, thi6 invention relat~ to ~uch rollg that
~ontain a ~urface layer of cured silicone material that
i B harder than the underlying rubber and to a method for
producin~ these rolls.
Contact thermal fixing i~ widely u6ed, for
example, in el~ctrophotographic copier~. In contact
thermal fixing, ~n image is electrophotographically
~ormed on the photoreceptor by toner ( a thermopla~tic
resin powder), sub~equently transferred to the transfer
~heet and then fixed in a fixing element to generate the
copy.
- Conta~t thermal ~ixing omploy~ a device
referred to a~ a heat-flxing roll a6 embly compri~in~ a
bard heated roll, whose ~urface ha~ both heat resistance
and relea~ibility, and a ~oft pressure roll, which
posse se~ heat resistance, relea~ibllity, and
flexibility. To ~ix a toner image the&e two heat-ix~ng
rOllB are pre~8ed together at a deslgned pre~sure, and
the image-carrying transfer paper i6 pas~ed between the
rolls~ Und2r these conditions the so~t roll should
undergo an inerea~e i~;conta~t area while in ~ontact with
.
r
~3~21D3~i
the hard roll in order to obtain a clear imag~. A
problem encountered with prior ar~ ~oft roll6 i~ their
tendency to as~ume a permanent set ~ecause they are
continually being deformed.
With reqard to the 60ft roll~ us~ed for paper
advance in, for example, fac~imile devices, ~oiling of
the original occur6 as a re~ult of use and accumulation
o powder from the paper and other 60urces, with the
result that the quality of the image is adversely
affected.
In attempting to solve these problems, rolls
have been proposed in which a relatively hard material
such as a fluorinated resin or a flexible metal i8
additionally coated around the outer circumference of a
low-hardnes~ rubber.
Japane~e Patent Publication No. 20232/80,
published on April 19, 1980, di~close a roller
comprising a metal core, an under-coat of a æpecified
organo~iloxane composition that ~l~o includes an allyl
ester of a polybasic acid, a metal ~alt of a fatty acid
and an alkoxysilane, and an outer coating of a ~ilicone
rubber.
Research Di~clo~ure Nos. 2178,033 and 217,034,
publiRhed by Kenneth Mason Publications, Ltd. on April
20, 1982 and U.S. Pat. No. 4,430,406, which issued to J.
Newkirk et al. on~May 4, 1983 disclose a roller
compri~ing an i~ner layer of a ~ilicone elastomer and an
outer layer of an elastomeric organic fluoropolymer or a
fluorosilicone that resi~t6 a~sorption of fusel oil
absorbed by the inner lRyer. An intermediate layer has a
compo~ition that changes continuously or ln a step-wi.e
manner from that of the inner layer to that of ~he outer
layer.
,
~3~2~35
West German Pat. No. 3,539,377, which issued on
May 22, 1986 describes a roller having an elastic
silicone rubber layer that is coated with a ~intered
fluorinated organic resin such as
polytetrafluoroethylene.
Japanese Patent Publication No. 26070/61, which
was published on February 5, 1986, is directed to a heat
fixing roll comprising a layer of silicone rubber sponge
and a hard layer formed on the outer surface of the
sponge rubber.
U.S. Pat. No. 4,329,565, which issued to Namiki
et al. on May 11, 1982, discloses a fixing roll
comprising a layer of resilient material that is overlaid
with a layer of offset-preventing material containing
from 1 to 5 percent of a thermally conductive metal
powder. The offset-preve~ting material can be a
silicone, fluorosilicone or organic resin.
Japanese Patent Publication No. 56854/57, which ` --`
issued on April 5,~1982 discloses a roller formed from a
heat hardenable silicone rubber that is coated with a
layer of anti-~tatic material prepared by adding a
peroxide and either sodium sulfate or a sulonamide to a
heat hardenable silicone rubber.
Canadian Pat. No. 1,116,549, which issued on
January l9, 1982 discloses a fuser roll for a copier
consisting essentially of a thermally conductive metal
tube coated with a thin layer of a cured silicone rubber.
The rubber layer exhibits a thickness of about 0.25 mm.
and is expo~ed to ultra-violet radiation under an inert
atmosphere following curing.
i3~2~:~S
Japanese P~tent Publication ~o. 38957/61, which
was publi~hed on August 20, 19B7 discloses forming a
roller by molding a silicone rubber on a metal core,
in~erting the roller into a tube formed from a
fluorinated resin and heating the resultant composite to
shrink the resin tuba on to the 6ilicone rubber layer.
Japanese Patent Publication No. 28213, which
i6sued on Febxuary 6, 1987, ~isclosP6 a method for
forming a cvpier roll by placing a heat-resistant resin
tube and a central core in a mold, pouring in a heat
resistant material ~uch as a curable silicone rubber
composition between the tube and the core to form an
intermediate layar that is then vulcanized to form an
elastomer.
Japanese Patent Publ~cation No. 26027/87, which
was publi~hed on June S, 1987 discloses a fixing roll
comprising a metal roll, an inner layer of a sili~one
rubber and an outer layer of a fluoro~ilicone rubber.
U.S. Pat. No. 4,149,7~7, which iR~ued to G.
Imperial on April 17, 1979 and U.S. Pat. No. 4,083,092,
which issued to ~mperial et al. on April 11, 1978
disclose a fixing roll comprising a rigid core, an
organic rubber layer adhered to the core and an outar
protective ~leeve. The ~leeve haæ a high flex life and
blocks air from reaching and oxidizing the rubber.
Soft rolls known in the art, including the
6ilicone rubber-covered rolls, suffar from the problems
of 1) not increa6ing in contact area along the line of
contact between ~he ~oft roll and the aforementioned hard
roll 2 ) and ~suming a permanent compres6ion set. As a
result, there i~ a ~trong tendency for the copy image to
be unclear.
i ,
~L3~;~1D3~;
- 5
The present inventors carefully studied methods
for eliminating these problems, and developed the present
inven^tion as a consequence.
An objective of the present invention is to
provide a soft roll coated with a silicone material which
is not subject to permanent set during use and which has
an excellent resistance to soiling. This invention also
provides a method ~or preparing these rolls.
A particular object of the present inven~ion is
to provide a soft roll whose contact area with an
adjacent hard roll can expand along the line of contact
with a hard roll. This provides a clear copy image when
the rubber-covered roll is used as a fixer roll in an
electrophotographic device.
Another objective is to provide a method ~or
the production of these soft rolls.
The aorementioned objectives can be achieved
by a roll wherein a first layer of cured silicone
material having a hardness no greater than 30 on the JIS
A scale is formed on a roll axle and covered with a
second layer of cured silicone material having a hardness
greater than that of the first layer.
The present invention resides in an improvement
in an unheated roll for a copier or facsimile device
comprising a metal roll axle coated with a cured silicone
rubber, which improvement comprises:
a. the presence on said roll of an inner layer
of cured silicone rubber having a first and a second
surface and a hardness of less than 30 on the Japanese
Industrial Standards (JIS) A scale, wherein said first
surface is in contact with said axle and said second
surface is in contact with an outer layer of cured
silicone rubber exhibiting a hardness greater than that
of said inner layer, where said roll is formed by
~L30~35
1) coating the interior surface of a mold with
an organohydrogenpolysiloxane having at least 3 silicon-
~onded hydrogen atoms per molecule,
2) mounting said roll axle in said mold,
3) introducing into said mold a curable liquid
silicone rubber composition that will yield said cured
silicone rubber having a hardness no greater than 30 on
the JIS A scale, and
4) curing said organohydrogenpolysiloxane and
said liquid silicone rubber composition by heating.
~ ~,
, .
~3~2~35
The pres0nt invention also provides a preferred
method for preparing the present silicone-covered roll.
In accordance with this method an organopolysil~xane
having at least 3 silicon-bonded hydrogen atoms in each
molecule is applied to the interior surface of a mold. A
roll axle is then introduced into the interior of this
mold, followed by introduction of a liguid silicone
composition that is convertible t~ the aforementioned
elastomeric cured material having a hardness no greater
than 30 on the JIS A scale. As the final step the
organopolysiloxane and liquid silicone rubber composition
are thermally cured.
No specific restrictions apply to the roll axle
used in the present invention. The axle is formed from a
metal typically used as a roll core metal. The surface
of the axle can be treated with an anticorrosive agent or
a primer.
The inner layer of the present roll is adjacent
to the roll axle and consists essentially of an
elastomeric cured silicone material having a hardness no
greater than 30 on the JIS A scale. This material is
obtained from an organopolysiloxane-based composition
that cures either at room temperature or upon heating.
The cured silicone material is not specifically
restricted, and includes silicone gels and conventional
silicone rubbers. The hardness of the cured material
must be no greater than 30 on the JIS A scale, measured
as specified in JIS C 2123. The hardness of the cured
silicone material is preferably no more than 20, and most
preferably no more than 10.
If the hardness value of the inner layer
exceeds 30 on the JIS A scale the roll will not exhibit
the advantages of the present invention.
~L3~2~3~;
The thickness of the inner layer is not
specifically restricted, and will depend upon the end use
application of the roll.
An outer layer of cured silicone material
having a hardness in excess of that of the aforementioned
inner layer of cured silicone material is the
characterizing feature of the present rolls. The
principal component of the cured surface layer is at
least one organopolysiloxane. Preferably the
organopolysiloxanes present in the inner and outer layers
are identical.
No specific restrictions apply to the outer
layer other than the fact that a tacky semi-cured
material or cured gel material is undesirable. Concrete
examples of cured materials suitable for use as the outer
layer are silicone rubbers and silicone resin~.
The cured outer layer must be harder than the
cured inner layer. A hardness value in the range of 35
to 90 on the JIS A scale is preferred for the outer
layer. When the hardness of the outer layer is less
than that of the cured inner layer, the roll will have a
tacky surface, and will not exh'bit the desired
resistance to soiling and development of a permanent
compression set.
The cured outer layer preferably has a
thickness of approximately 1/10 to 1/1000 that of
aforementioned inner layer. The thickness of the outer
layer is preferably no greater than 1,000 microns.
The mold used to manufacture the silicone-
covered roll in accordance with the present method can be
formed from metal, silicone rubber, or a synthetic resin
such as a polyester or nylon. These materials are
typically used as mold materials for silicone rubber
compositions
: ~`
~L3~2~3S
No specific res~ictions apply to the mold so
lvng a~ the curable lisuid ~ilicone rubber comp~sition
can flow into the mold and be ~ubsequently cured.
In accordance with a preferred method for
preparing the present roll an organopolysiloxane
containing at lea~t 3 silicon bonded hydro~en atom~ is
applied to t~e interior ~urface of the mold, the roll
axle i~ placed in-~he center of the mold cavity and the
cavity is ~ubsequently filled with a cur~ble liquid
æilicone composition that will form the inner layer of
~; the roll upon curing. The organopolysiloxane is in
contact with and cures together with the curable liquid
Eilicone composition during molding to form the hard
outer layer o~ the roll. Although thi~
organopolys~loxane must have at least 3 ~ilicon-bonded
hydrogen atom~ in each molecule, it can be used in
combination with an organopolysiloxane having 2
: ~ilicon-bonded hydrogen atoms in each molecule to vary
the h~rdnes~ of ~he outer layer.
The molecular structure of the
organopolysiloxane containing at least three -
silicon-bonded hydrogen atoms per molecule is not
~pecifically restxicted. The molecular structure of thi6
molecule may be ~traight chain, branch-containing
straight chain, or cyclic. When a harder and tougher
outer layer must be formed at the 6urface of the
~ilicone~covered roll, it is pre~erable to use a branched
~: organopolysiloxane, for example, a copolymer composed of
~CH337HSiOl~2 and SiO4/2 units, or a copolymer o~
(C~3)3silJ2' ~CH3)2Hsiol/2~ and SiO4/2
Non-limiting examples of the organopoly~ilox~ne
ingredient include but are not limited to
trimethylsiloxy-terminated me~hylhydrogenpolysiloxanes.
7.
~:
s
trimethylsiloxy-terminated
dimethylsiloxane-methylhydrogensiloxane copolymers,
dimethylhydrogensiloxy-terminated dimethylsiloxane-
methylhydrogensiloxane copolymers, d:Lmethylsiloxane-
methylhydrogensiloxane cyclic copolymers, copolymerscomposed of (CH3)2HSiol/2 and Sio4/2 units, and
copolymers composed of (CH3)3SiOl/2l (CH3)2HsiOl/2~ and
SiO4/2 units.
The organopolysiloxane can be applied to the
inner surface of the mold by any of the known
conventional means, including spraying, brushing and
sponge coating. No specific restrictions apply to tha
quantity of organopolysiloxane, applied to the inner mold
surface, as long as a continuous, dry film is formed on
the mold surface.
The curable liquid silicone composition that
forms the inner elastomer layer of the present roll can
be a liquid or paste at room temperature, and is based on
a reactive group-containing liquid organopolysiloxane, a
crosslinker and~or a curing catalyst. The composition is
capable of curing into a rubbery elastomer or gel at room
temperature or with heating. It can be of the "sag" or
"non-sag" type.
The curing mechanism of this composition is not
critical, and can be an addition-reaction mechanism,
organoperoxide-based radical reaction-curing mechanism,
or condensation-reaction mechanism. Compositions that
cure by means o~ an addition reaction are preferred in
order to obtain a faster and more uniform curing.
Particularly preferred addition-curable liquid silicone
compositions for use in preparing the inner elastomer
layer comprise (A) an organopolysiloxane having at least
i~
~3~2~3S
2 lower alkenyl groups in each molec~lle; (B) an
organopolysilo~ane having at least 2 silicon-bonded
hydroyen atoms in each molecule, in a quantity such that
the molar ratio of the total quantity of silicon-bonded
hydrogen atoms in the present component to the total
quantity of all lower alkenyl groups in component ~A) is
from 0.1 to 1; and (C) a concentration of a platinum-type
catalyst equivalent to from 0.1 to 1,000 weight parts
platinum metal for each one million weight parts of the
total of components (A) and (B).
Component (A) of the preferred curable
compositions is the principal component of the
composition. Curing of the composition proceeds by the
addition reaction of component (A) with component (B)
under the catalytic activity of component (C). Component
(A~ must contain at ].east 2 silicon-bonded lower alkenyl
radicals-in each molecule. These lower alkenyl radicals
.
are exempli~ied by vinyl, allyl, and propenyl.
The alkenyl radicals of ingredient (A) can be
present at any location in the molecule, but are
preferably present at least at the molecular terminals.
The molecular configuration of this component can be
straight chain, branch-containing straight chain, cyclic,
or network, but is preferably straight chain, possibly
slightly branched. No specific restriction applies to
the molecular weight of this component. Also, while the
viscosity may range from that of low-viscosity liquids to
very high-viscosity gums and thus i~ not specifically
restricted, the viscosity at 25C is preferably at least
100 centipoise (0.1 Pa.s) in order to obtain a cured
material in the form of a rubbery elastomer. Examples of
this alkenyl-substituted organopolysiloxane include but
~l3~
are not limited to methylvinylpolysiloxanes,
methylvinylsiloxane-dimethylsiloxane copolymers,
dimethylvinylsiloxy-terminated dimethylpolysiloxanes,
dimethylvinylsiloxy-terminated
dimethylsiloxane-methylphenylsiloxane copolymers,
dimethylvinylsiloxy-terminated
dimethylsilo~cane-diphenylsiloxane-methylvinylsiloxane
copolymers, trimethylsiloxy-terminated
dimethylsiloxane-methylvinylsiloxane copolymers,
trimethylsiloxy-terminated
dim thylsiloxane-methylphenylsiloxane-methylvinylsiloxane
copolymers, dimethylvinylsiloxy-terminated
methyl(3,3,3-trifluoropropyl)polysiloxanes,
dimethylvinylsiloxy-terminated
dimethylsiloxane--methyl(3,3,3-trifluoropropyl)siloxane
copolymer~, and polysiloxane~ consisting essentially of
2 ( H3)2Si1/2~ (CH3)3siol/2~ and SiO4/2 units
Combinations of the above organopolysiloxanes can also be
used in the present invention.
. Component tB) of the preferred compositions or
preparing the inner elastomer layer of the present rolls
is a crosslinker for component (A). Curing proceeds by
the addition of the silicon-bonded hydrogen atoms in this
component with the lower alkenyl groups in component (A)
under the catalytic activity of component (C). This
component (B) must contain at least 2 silicon-bonded
hydrogen atoms in each molecule in order to function as a
crosslinker.
The molecular structure of component (B) is not
specifically restricted, and can be straight chain,
branch-containing straight chain, or cyclic. The
molecular weight of this component is likewise not
specifically restricted, however the viscosity of this
1~
~L3~2Q135
component, me~ured at 25bC., i6 preferably 1 to SO,OOO
centipoi~e ~0.001 to 50 P~.~) in order to obtain goQd
mi~cibility with component (A).
The concentration of component ~B) is
preferably one ~hat will provide a molar ratio of
~ilicon-bonded hydrogen atoms to all lower alkenyl
radical~ in c~mpo~ent (A) of from 0.1 to l. MGst
preferably t~iB ratio i6 fro~ 0.~ to 0.6. 'rhe
crosslinking density will be too low at molar ratios
below 0.1, re~ulting in un6ati~factory curing. On the
other hand, the cro~lin~ing den~ity of the cured inner
layer will be too high when the molar ratio
8i licon-bonded hydrogen atoms to total alkenyl radicals
exceeds 1, and it will be difficult to orm a hard
covering layer at the ~urace o~ the ~l$cone-covered
roll.
It will be unders~ood that when the curable
compo~ition u~ed to form the inner-elastomer layer
incl~d~ an additional organopoly~iloxane containing a
large concentration of alkenyl radicals for the purpo~e
of providing rei~forcement or other properties to the
cured elastomer, th~ amount of organopolysiloxane
containing siliton-bonded hydrogen atom i8 preferably
~ufficient to react with thee2 additional alkenyl
radicals.
Examples ~f component (B~ include but are not
limited to trimethyl~iloxy-terminated
methylhydroge~poly~ilox~ne > trimethyl~iloxy-terminated
dimethylsiloxane-methylhydrogen~iloxane copolymers,
dimethylhydrogensiloxy-terminated
dimethyl~iloxane-methylhydrogen~iloxane copolymer~,
1~
i ~`
i" .", ~
~30;~35
.
dimethylsiloxane-methylhydrogensiloxane cyclic
copolymers, copolymers composed of (CH3~2HSiO1/2 and
SiO4/2 units, and copolymers composed of (CH3)3$iO1~2,
(CH3)2HsiOl/2~ and SiO4/2 units.
Component (C) of the preerred curable
compositions is a catalyst for the addition reaction of
silicon-bonded hydrogen atoms with alkenyl radicals.
Non-limiting examples of this component include
chloroplatinic acid, including solutions of this catalyst
in alcohol or ketone and these solution following aging,
chloroplatinic acid-olefin complexes, chloroplatinic
acid-alkenylsiloxane complexes, chloroplatinic
acid-diketone complexes, platinum black, and platinum
supported on a carrier.
Component ~C) is present in an amount
equivalent to from 0.1 to 1~000 weight parts of
platinum-group metal for each one million parts by weight
(ppm) of the total guantity of components (A~ and`~~BF.'`~
The crosslinking reaction will not proceed satisfactorily
at below O.l ppm, while exceeding 1,000 weight parts is
uneconomical. In the typical case, the preferred
catalyst concentration is equivalent to approximately 1
to 100 ppm of platinum-group metal.
The curable liquid silicone compositions used
to form the inner layer of the present roller can include
at least one filler to adjust the fluidity and/or
improve the mechanical strength of the molded article.
These fillers are exemplifi~d by reinforcing fillers such
as precipitated silica, fumed silica, calcined silica,
and fumed titanium dioxide, and by non-reinforcing
fillers such as quartz powder, diatomaceous earth,
asbestos, aluminosilicic acid, iron oxide, zinc oxid~,
13012~35
and calcium car~onat~. The ~urface of the filler can
optionally be treated with a~ organo~ilicon compound, for
example, hexamethyldisilazane, trimethylchloro~ilane~ or
a hydroxyl terminated polydimethyl~iloxane.
Ths prasent curable liguid 6ilicone
compogition~ can al~o include ~mall or very ~mall amount~
of inhibitor~ for the curing reactionr BO long a~ the~e
inhibitor~ do not adversely affect the objectives of the
pre~en~ invention. Non-limiting ~xample~ of ~uch
inhibitors include acetylenic compounds, hydrazines,
triazole , phosphineR, and mercaptans.
Other optional inqredients that can be pre~ent
in the curable precursor of the elastomeric inner layer
include but are not limited to pigment8, heat
stabilizers, flame retardants, plaBticizer~ and
organopolyciloxanes having 1 alkenyl radical i~ each
molecule that are added to reduce the modulus of the
cured ela~tQmeris inner.layer.
A second ciaa of preferred curable ligui~
organosiloxana compositions cure by means of a free
radical reaction and include an organoperoxide as the
curing ~gent. The~e ~ompo~itions include a vinyl
group-containin~:diorganopolysiloxane that is li~uid at
room temperature and a catalytic quantity of
organoperoxide. Optional ingredients include but are not
limited to inorganic filler6 ~uch as fumed silica and
precipitated silica, heat stabilizers, and pigments. The
organoperoxide preferably has a decomposition temperature
in the range of ~25 to ~100C.
Compressio~ molding, transfer molding, and
in~ection molding are typically used to mold liquid
cilicone rubber composit on~, and can be u3ed to
introduce the pre~ent curable liguid silicone rubber
compo~ition into the in~erior of the mold ~nd thermally
cure them.
~ f~
131[~2~
3S
When the temperature used to cure the curable
llquid 6ilicone ma~erial is too low, the curing rate will
be reduced ~nd the productivity will be low. On the
other hand, when the molding ~emperature il3 to~ high, ~he
re~ul~ing ~ilicone ela6tomer molding will ~stick to the
i~terior surface of the mold, thus generat:ing problems in
de-moldinq. Ac a con~eguence, the molding temperature
æhould be within the range of from 50 to 220~C and
preferably in the range of 50 to 170C.
The sllicone-covered roll of the present
lnvention finds use in various applications, ~or example,
as the transfer roll~, fixing rolls, or c~eaning rol}s
used in electrophotographic copiers, and as
paper-advance roll~ in ac~imile devices.
The following examples describe preerred
e~bodiment~ of the prssent rolls, and should not be
-~nterpreted as limiting the scQpe of the invention a~ ~ _
de~ined in.the accompanying claims. Unless otherwise
~pecified.all part~ ~nd percen~age~ are by weight a~d
vi~coæities were measured at 25~C.
Example 1
100 Part6 of a dimethylvinylsiloxy-terminated
dimethylpoly~iloxane having a viscosity o~ 2000
centipoise (2 Pa.s) and a vinyl content of 0.23 wt%, 25
part~ dry-me~hod silica having a ~pecific ~urface area o~
200 sguare meter~ per gram, and 0.5 parts
tximethyl~iloxy-terminated methylhydrogen-
poly iloxane having a ~i6cosity of 10 centipvi~e (0.01
Pa . ~) and a SiH ~ilicon-~onded hydrogen content of 0.9%
were blended to homcgeneity to provide a mixture having a
vi~co~ity o~ 5~000 poise (500 Pa.~j at a ehear rate of 1~
,. 1~
: .,
~l3(~13~i
Bec 1, A curable liquid ~ilicone composition of this
invention wa~ obtained by bl~nding this ~uxture together
with 0.1 par~ of a ~olution of chloroplatinic acid in
i opropanol. The solution contained 3 percent of
platinum.
A metal mold designed for the moldi~g of
~ilicone ela~tomer-covered rolls and having a
chromium-plated interior ~urface was coated on it~
interior surface with a trimethylsiloxy-terminated
methylhydrogenpoly6iloxane having a vi6cosity of 10
centi~tokes (10 5 m2/sec.) and a silicon bonded hydrogen
atom content of 1.0 wt% to yield a uniform coating
density o~ 0.2 g per square meter.
A cylindrical iron roll axle was al50 prepared,
and coated with a primer consisting essentially of an
organopoly~iloxane gum~ an organopolysiloxane resin,
ethyl ~ilicate, a ~ethylhydro~enpoly6iloxane. and an
organotita~ate ~ster. The primer was applied ~o th~
ur~ace of the roll and subs~quently cured.
The primed roll axle wa~ mounted in~ide the
aforementioned metal mold, and the liguid ~ilicone
~omposition prepared as described in the preceding
portion of thi~ ~xample was then injected into the cavity
and thermally cured at 150C for lO rninutes. After
cooling, ~he obtained ~ilicone~-covered roll wa~ removed
and the interior portion o~ the coating was expo~ed by
cutting lnto the coating u~ing a knife.
The hardness of the $nterior and exterior
layers of the roll coating was then mea6ured using the
JIS A scale with the following results: surface layer
hardness - 50, inner layer hardne6s = 10. The thickness
of the outer layer wa~ ~.5 mm.
~13~2~35
The resiliency of the rubber layer wa~ 10% and
the permanent compree6io~ ~et was 15%. Th~ compreC6ion
æet value was o~tained by compressing the rub~er layer to
75% of its initial thicknesR for a period of 72 hour~
while heating the roll at a temperature of lB~C.
When this ~ilicone ela~tomer-covered roll wa~
u~ed a~ the pressure roll in the fixing roll of an
electroph~tographic copier, ~he copy paper wa~ not
creased, and the copied image was clear.
Example 2
100 Part~ of a dimethylvinyl6iloxy-terminated
dimethylpolysiloxane having a vi~cosity of ~000
centipoi~e (2 Pa. 5 ) and a vinyl content of 0.23 wt%l ~0
parts dry-method silica having a ~pecific surface area of
200 ~guare meterC per gram, 0.4 parts trimethylsiloxy-
terminated methylhydrogenpoly6i}0xane having a SiH
content of ~.0 wt%, and Ool part of a ~olution of
chloroplatinic acid 801ution in isopropanol (plati~um
content = 3 percent) were blended t9 homogeneity to
produce a curable liguid ~ilicone compo6itio~ of thi~
invention. The ~ame methylhydrogenpoly6iloxane described
in the preceding Example 1 wa~ ~prayed on the interior
~urface of ~n m~tal injection mold. The mold was heated
to a temperature of 120C at which time an iron roll core
was mounted in the interior of the~mold, and the liquid
silicone ~ompo~ition prepared as above was the~ injected
and cured. The hardne s values of the exterior and
interior lay~r~ o~ the resultant ilicone elastomer-
covered roll of thi invention were mea~ured a described
in the preceding Example 1, and were 38 and 3,
respectively, measured using the JIS A ~cale. When this
roll was u~ed a~ a paper-advance roll in a fac6imile
device neither the roll ~urface nor ~he image were
~oiled.
1~
,.
~3(:~203~
Example 3
100 Part~ of a dimethylvinylsiloxy-terminated
dimethylpoly iloxane having a visc06ity of 2000
centipoise (2 ~. 8) and a vinyl conten~ of 0.23 wt%, 15
part of carbon blaok having a specifiG ~urface area of
70 ~quare meters per gram (available as Denka Bl~ck*~rom
Denki Kagaku Kogyo ~abu~hi~i ~aisha) and Q.4 parts of a
trimethyl~iloxy-terminated methylhydrv~enpoly~iloxane
having a vi6cosity of 10 centipoige ~0.01 Pa.~) and a
#ilicon-bond~d hydrogen atom ~ontent of 1.0 wt% were
blended to ha~eneity of yield a mixture having a
viscosity of 800 po~se ~80 Pa.~) at a shear rate of 100
~ec 1. To this mixture wa~ added 0.1 part of the
chloroplatinic acld ~olution described in the preceding
Example 1 to produce a curabl~ liquid silicone rub~er
composit~on of this invention.
A cylindrtcal metal mold having a chromium~
plated inner ~urface was coated with a cylindrical -
~preformed polyester film and a 10% fiolution in toluene of
a trimethyl~iloxy-terminated methylhydrogenpolysiloxane
exhibiting a viscosity o~ 10 cer.tistokes (lxlO 5 m2~ec~
and eo~taining 1 percent of ailicon- bond~d hydrogen was
sprayed on the expo~ed surface of the film to produce a
c~ating density o~ 5 gram~ per ~guare meter. The coating
was then dried. An alumi~um roll axle was then inserted
into the cavity'~ interior, and the liguid ~ilicone
rubber comps~ition prepared a~ described in the precedin~
portion o~ ~hi~ Example wa~ then in~ected and thermally
cured at 139C for 5, minutes. ~e re~ultin~ molding wa~
a silicone-covered roll having an inner gel layer
(hardness = 5) and a 0.4 mm-thick hard cover~ng layer at
*Trad ~ rk
1)3~;
the surface. This silicone elastomer-covered roll of
this invention was used as the pressure roll in the
fixing rolls of an electrophotographic copier. No
permanent compression set in the roll was observed, and
the copied image was clear.
,~
2~
