Stock material or miscellaneous articles – Composite
Reexamination Certificate
2000-07-06
2003-03-11
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
C428S906000, C399S297000, C399S308000, C492S056000
Reexamination Certificate
active
06531227
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an intermediate medium with a rubber top layer which contains a conductive material for use as a temporary image support in an imaging device or system. The imaging device uses the intermediate medium of this kind as the temporary image support.
Imaging techniques in which an image is formed on a temporary image support with a rubber top layer, and said image is transferred under pressure, possibly combined with a supply of heat, to a final receiving material, are known in various forms. In one very well known embodiment, a toner powder image is formed on a re-usable imaging element, such as a photoconductive element, a magnetic imaging element or an electrostatic imaging element containing a dielectric image receiving layer, and said toner powder image is transferred under pressure to an intermediate medium as specified above. The toner powder image is heated on the intermediate medium to make the toner powder tacky, whereafter in a second pressure transfer zone the tacky image is transferred and at the same time fixed on a final receiving support. The latter is heated if necessary before being introduced into the pressure transfer zone. After the image transfer in the second pressure transfer zone, an additional fixing step can take place if necessary to provide optimal fixing of the image on the final image receiving support. Also, in addition to or instead of the additional fixing step, other finishing operations can take place, for example, a gloss treatment. After-treatments of this kind are carried out particularly in the case of (multi-)color images.
Other imaging processes in which intermediate media with a rubber top layer can be used, are processes in which liquid ink or melted ink (hot melt ink) directly form an image on the top layer by means of an ink jet print head and the image is then transferred to the final receiving material.
The rubber top layer of the intermediate medium must have good mechanical and chemical permanency and should particularly be insensitive to the (low-melting) substances (waxes, plasticizers, etc.) released from the receiving materials, particularly receiving papers. The rubber must also have a certain electric conductivity to obviate electrostatic charges. Conventional rubbers for forming such a top layer are silicone rubbers and perfluoropolyether rubbers (PFPE-rubbers).
NL-A 1 001 471 proposes an intermediate medium wherein the rubber is a perfluoropolyether (PFPE) rubber. The top layer containing the PFPE-rubber described therein gives high resistance to the transfer of low-melting impurities. A process for the preparation of a PFPE-rubber by curing a lengthened-chain bifunctional PFPE-oil is described. In one embodiment, furnace black is added as a filler and conductive material to the PFPE-oil, whereafter thermal curing is carried out. In addition, a process is described for the preparation of the lengthened-chain PFPE-oils used as starting material, in which process a PFPE-oil having a weight-averaged molecular weight (Mw) in the range from 1500 to 3000 g/mol is reacted with a lengthened-chain agent selected from the group of di-acid chlorides and di-isocyanates.
One disadvantage of the embodiment of NL-A 1 001 471, in which furnace black is contained in the PFPE-rubber-containing top layer, is that the conductivity of the PFPE-rubber cannot be adjusted within a required bandwidth and the PFPE-rubber is therefore not anti-static. Another disadvantage is that the conductivity with furnace black in the antistatic PFPE-rubber is not stable. Deformation of the PFPE-rubber in fact causes the conductive furnace black paths to be broken. Yet another disadvantage is the difficulty of curing with UV radiation a PFPE-oil with which furnace black has been mixed.
In addition, the prior art makes a number of proposals according to which, in addition to furnace black, other conductive materials such as intrinsically conductive polymers, can be included in the top layer.
For example, U.S. Pat. No. 5,629,094 relates to a transfer material support consisting of a substrate and a top layer. The substrate preferably consists of a resin such as a polyester, polycarbonate, polyvinylidene fluoride, Teflon, polyurethane or polyacetate. The top layer contains a polyester resin, a hardened resin and a silicone polymer. This top layer can also contain polycarbonate, polyamide, polyacrylate, polyoxymethylene, polyphenylene oxide, polyphenylene sulphide, polyethylene, polypropylene, polystyrene, a copolymer of ethylene and propylene, a copolymer of styrene and butadiene, and so on. In addition, the top layer or the substrate may contain conductive materials such as metal powder, metal oxides, gas black, graphite, carbon fibers, organic or inorganic electrolytes and intrinsically conductive polymers such as polypyrrole or polyaniline.
U.S. Pat. No. 5,534,581 describes a transfer material support consisting of a copolycarbonate resin and conductive particles. The conductive particles comprise furnace black, metal oxides or intrinsically conductive polymers, such as polyaniline, polythiophene and polyacetylene. The conductive particles are dispersible in high concentration in the copolycarbonate resin.
U.S. Pat. No. 5,430,073 relates to a process for the preparation of intrinsically conductive polymers comprising in situ activation of precursor monomers whereby activated monomers are obtained which polymerize in the presence of a catalyst. Polymerization without activation of the precursor monomers is prevented. The intrinsically conductive polymers can, for example, be formed after mixing the precursor monomers in a polymer matrix. The intrinsically conductive polymers which are prepared with this process comprise polypyrrole, polythiophene and polyfurane which may or may not be substituted and mixtures of two or more of these polymers.
SUMMARY OF THE INVENTION
The object of the present invention is to include an intrinsically conductive polymer as a conductive material in a PFPE or silicone rubber, instead of furnace black, to ensure that a rubber is formed which is antistatic. Intrinsically conductive polymers, however, are insoluble in the rubber oil (PFPE or silicone oil) used as starting material. The present invention thus provides an intrinsically conductive polymer which is so modified that it can be combined with the rubber oil.
Accordingly, the present invention relates to an intermediate medium for use as a temporary image support in an imaging device, as described in the preamble, wherein the conductive material is an intrinsically conductive polymer so modified that it can be combined with the rubber oil.
PFPE-rubber or silicone rubbers can be used as the rubber. The preferred PFPE-rubber is as described inter alia in NL-A 1 001 471.
Conventional polymers, inter alia, as described in U.S. Pat. Nos. 5,629,094; 5,534,581 and 5,430,073, can be used as intrinsically conductive polymer. Examples are polyaniline, polypyrrole, polythiophene. A very suitable polymer is a modified polyaniline. The conductive polymer can be modified in various ways.
For example, a conductive polymer can be used that is doped with a PFPE-carboxylic acid. The PFPE-carboxylic acid preferably has the formula:
F
3
C[(OCF
2
—)
p
—(OCF
2
CF
2
—)
q
]OCF
2
—COOH
where p and q are in the range of 5 to 9. An advantage of such a modified conductive polymer is that a high intrinsic conductivity and good miscibility in a PFPE-oil used as a starting material can be obtained.
Preferably, the polyaniline used is modified by substituting it on the aromatic ring with a PFPE-chain. Particularly preferred is the use of a modified polyaniline which is a copolymer formed by the polymerization of aniline and aniline substituted on the aromatic ring with a PFPE-chain. The PFPE-chain is preferably a linear [(OCF
2
)
m
(OCF
2
C—
F2
)
n
] chain where m and n are in the range of 9 to 13. One advantage of such modified polyanilines is that very good miscibility in a PFPE-oil used as a starting material can be obtained.
Th
Beers Edgarius Jakobus Hermanus
van den Reek Johannes Adrianus
van Zeeventer Karel Pieter Daniel
Birch & Stewart Kolasch & Birch, LLP
Oce--Technologies B.V.
Thibodeau Paul
Zacharia Ramsey
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