Electrophotography – Image formation – Transfer
Reexamination Certificate
1999-08-17
2002-01-01
Metzmaier, Daniel S. (Department: 1712)
Electrophotography
Image formation
Transfer
C399S307000, C399S308000, C428S421000, C428S447000, C524S262000, C430S124300
Reexamination Certificate
active
06336026
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to crosslinked fluorosilicone materials. More specifically, the present invention is directed to thermally stabilized crosslinked fluorosilicone materials suitable for applications such as transfer members for imaging processes and the like. One embodiment of the present invention is directed to a transfer member comprising a crosslinked product of a liquid composition which comprises (a) a fluorosilicone, (b) a crosslinking agent, and (c) a thermal stabilizing agent comprising a reaction product of (i) a cyclic unsaturated-alkyl-group-substituted polyorganosiloxane, (ii) a linear unsaturated-alkyl-group-substituted polyorganosiloxane, and (iii) a metal acetylacetonate or metal oxalate compound, said transfer member having surface a resistivity of from about 10
4
to about 10
16
ohms per square.
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. Generally, the electrostatic latent image is developed by bringing a developer mixture into contact therewith. The developer mixture can comprise a dry developer mixture, which usually comprises carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which can include a liquid carrier having toner particles dispersed therein. The developer material is advanced into contact with the electrostatic latent image and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a copy sheet.
It can be advantageous to transfer the developed image to a transfer member, and subsequently to transfer the developed image from the transfer member to a permanent substrate with very high transfer efficiency. The toner image is subsequently usually fixed or fused upon a support, which can be the photosensitive member itself, or can be any other desired support sheet, such as plain paper.
Transfer members allow for positive attributes such as high throughput at modest process speeds, improved registration of the final color toner image in color systems using synchronous development of one or more component colors using one or more transfer stations, and increased range of final substrates that can be used.
In electrostatographic printing machines wherein the toner image is transferred from the transfer member to the image receiving substrate, the transfer of the toner particles from the transfer member to the image receiving substrate preferably is as complete as possible. Less than complete transfer to the image receiving substrate can result in image degradation and low resolution. Efficient transfer is particularly important when the imaging process entails generating full color images, since undesirable color deterioration in the final colors can occur when the color images are not completely transferred from the transfer member.
Accordingly, the transfer member surface preferably has excellent release characteristics with respect to the toner particles. Conventional materials known in the art for use as transfer members often possess the strength, conformability, and electrical conductivity necessary for use as transfer members, but can suffer from poor toner release characteristics, especially with respect to higher gloss image receiving substrates.
Although use of a release agent increases toner transfer, the transfer member outer layer can swell upon addition of the release agent. For example, silicone rubber performs well as a transfer layer, but swells significantly in the presence of a hydrocarbon fluid release agent. In addition, release properties have been shown to decay from repeated interaction with certain release agents such as hydrocarbon release agents.
Preferably, the resistivity of the transfer member is within a preferred range to allow for sufficient transfer. The transfer member also preferably has a controlled resistivity, wherein the resistivity is virtually unaffected by changes in humidity, temperature, bias field, or operating time. In addition, a controlled resistivity is desirable so that a bias field can be established for electrostatic transfer. The transfer member preferably is not too conductive, since air breakdown can possibly occur in that instance.
Attempts at controlling the resistivity of transfer members have been performed by, for example, adding conductive fillers to the outer layer. Use of carbon black as a conductive filler has been disclosed. Carbon black has been the chosen additive for imparting conductive properties in electrostatographic films. Carbon black is relatively inexpensive and very efficient in that a relatively small percentage can impart a high degree of conductivity. Many doped metal oxides can also be employed to impart desired conductivity to the member.
U.S. Pat. No. 5,864,740 (Heeks et al.), the disclosure of which is totally incorporated herein by reference, discloses a thermally stabilized silicone liquid composition and a toner fusing system using the thermally stabilized silicone liquid as a release agent, wherein the thermally stabilized silicone liquid contains a silicone liquid and a thermal stabilizer composition (including a reaction product from at least a polyorganosiloxane and a platinum metal compound (Group VIII compound) such as a ruthenium compound, excluding platinum.
U.S. Pat. No. 5,493,376 (Heeks), the disclosure of which is totally incorporated herein by reference, discloses a thermally stabilized polyorganosiloxane oil including a polyorganosiloxane oil and, as the thermal stabilizer, the reaction product of chloroplatinic acid and a member selected from the group consisting of a cyclic polyorganosiloxane having the formula
where R
3
is an alkyl radical having 1 to 6 carbon atoms and R
4
is selected from the group consisting of alkene and alkyne radicals having 2 to 8 carbon atoms, and n is from 3 to 6; a linear polyorganosiloxane having the formula
wherein R
1
and R
2
are selected from the group consisting of hydroxy and alkyl, alkoxy, alkene, and alkyne radicals having 1 to 10 carbon atoms, provided that at least one of R
1
and R
2
is alkene or alkyne, and m is from 0 to 50; and mixtures thereof, present in an amount to provide at least 5 parts per million of platinum in said oil.
U.S. Pat. No. 5,395,725 (Bluett et al.), the disclosure of which is totally incorporated herein by reference, discloses a process for fusing toner images to a substrate which comprises providing a fusing member having a fusing surface; heating the fuser member to an elevated temperature to fuse toner to the substrate; and applying directly to the fusing surface a fuser release agent oil blend composition; wherein volatile emissions arising from the fuser release agent oil blend are minimized or eliminated.
U.S. Pat. No. 4,150,181 (Smith), the disclosure of which is totally incorporated herein by reference, discloses a contact fuser assembly and method for preventing toner offset on a heated fuser member in an electrostatic reproducing apparatus which includes a base member coated with a solid, abrasion resistant material such as polyimide, poly(amide-imides), poly(imide-esters), polysulfones, and aromatic polyamides. The fuser member is coated with a thin layer of polysiloxane fluid containing low molecular weight fluorocarbon. Toner offset on the heated fuser member is prevented by applying the polysiloxane fluid containing fluorocarbon to the solid, abrasion resistant surface of the fuser member.
U.S. Pat. No. 3,002,927 (Awe et al.), the disclosure of which is totally incorporated herein by reference, discloses organosilicon fluids capable of withstanding high temperatures which are prepared by preoxygenating the fluid by heating a mixture of (1) a polysiloxane fluid in which the siloxane units are selected from the
Badesha Santokh S.
Gervasi David J.
Heeks George J.
Henry Arnold W.
Byorick Judith L.
Metzmaier Daniel S.
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