Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2001-09-28
2002-06-25
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
Reexamination Certificate
active
06410196
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a novel charge transport layer composition of a photoreceptor used in electrophotography. More in particular, the invention relates to a polycarbonate binder for use in a charge transport layer.
2. Description of Related Art
In the art of electrophotography, an electrophotographic plate comprising a photoconductive insulating layer on a conductive layer is imaged by first uniformly electrostatically charging the surface of the photoconductive insulating layer. The plate is then exposed to a pattern of activating electromagnetic radiation such as light, which selectively dissipates the charge in the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image in the non-illuminated areas. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic toner particles, for example from a developer composition, on the surface of the photoconductive insulating layer. The resulting visible toner image can be transferred to a suitable receiving member such as paper.
Electrophotographic imaging members are usually multilayered photoreceptors that comprise a substrate support, an electrically conductive layer, an optional hole blocking layer, an optional adhesive layer, a charge generating layer, a charge transport layer, and optional protective or overcoating layer(s). The imaging members can take several forms, including flexible belts, rigid drums, etc. For most multilayered flexible photoreceptor belts, an anti-curl layer is usually employed on the back side of the substrate support, opposite to the side carrying the electrically active layers, to achieve the desired photoreceptor flatness. One type of multilayered photoreceptor comprises a layer of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder.
U.S. Pat. No. 4,265,990 discloses a layered photoreceptor having a separate charge generating (photogenerating) layer (CGL) and charge transport layer (CTL). The charge generating layer is capable of photogenerating holes and injecting the photogenerated holes into the charge transport layer. The photogenerating layer utilized in multilayered photoreceptors include, for example, inorganic photoconductive particles or organic photoconductive particles dispersed in a film forming polymeric binder. Inorganic or organic photoconductive materials may be formed as a continuous, homogeneous photogenerating layer.
Examples of photosensitive members having at least two electrically operative layers including a charge generating layer and diamine containing transport layer are disclosed in U.S. Pat. Nos. 4,265,990, 4,233,384, 4,306,008, 4,299,897 and 4,439,507. The disclosures of these patents are incorporated herein in their entirety.
Charge transport layers are known to be comprised of any of several different types of polymer binders that have a charge transport material dispersed therein. For example:
U.S. Pat. No. 6,242,144 describes a charge transport layer including an electrically inactive resin binder such as polycarbonate resin, polyester, polyarylate, polyacrylate, polyether, polysulfone, and the like, with weight average molecular weights varying from about 20,000 to about 150,000. It is further indicated that preferred binders include polycarbonates such as poly(4,4′-isopropylidene-diphenylene)carbonate (bisphenol-A-polycarbonate), poly(4,4′-cyclohexylidinediphenylene) carbonate (referred to as bisphenol-Z polycarbonate), and the like.
U.S. Pat. No. 6,020,096 similarly describes that a photoreceptor includes a charge transport layer including any suitable electrically inert film forming polymeric binder such as poly(4,4′-isopropylidene-diphenylene)carbonate, poly(4,4′-isopropylidene-diphenylene)carbonate, poly(4,4′-diphenyl-1,1′-cyclohexane carbonate), polyaryl ketones, polyester, polyarylate, polyacrylate, polyether, polysulfone, and the like.
U.S. Pat. No. 6,171,741 describes that a photoreceptor includes a charge transport layer including an electrically inactive resin material, preferably polycarbonate resins having a weight average molecular weight from about 20,000 to about 150,000. The most preferred polycarbonate resins are poly(4,4′-dipropylidene-diphenylene carbonate) with a weight average molecular weight of from about 35,000 to about 40,000, available as LEXAN 145 from General Electric Company; poly(4,4′-isopropylidene-diphenylene carbonate) with a weight average molecular weight of from about 40,000 to about 45,000, available as LEXAN 141 from the General Electric Company; a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 120,000, available as MAKROLON from Bayer Corp.; and a polycarbonate resin having a weight average molecular weight of from about 20,000 to about 50,000 available as MERLON from Mobay Chemical Company. It is also described that methylene chloride solvent is a desirable component of the charge transport layer coating mixture for adequate dissolving of all the components and for its low boiling point.
In addition, U.S. Pat. No. 5,728,498 describes a flexible electrophotographic imaging member including a supporting substrate coated with at least one imaging layer comprising hole transporting material containing at least two long chain alkyl carboxylate groups dissolved or molecularly dispersed in a film forming binder.
What is still desired is an improved binder for a charge transport layer of an imaging member (photoreceptor) that exhibits excellent performance properties the same as or better than existing binder materials discussed above, and has a further advantage of being coated using a solvent that is more environmentally friendly than methylene chloride.
SUMMARY OF THE INVENTION
It is therefore one object of the invention to develop a novel binder resin for use as a charge transport layer binder.
It is a still further object of the present invention to develop a charge transport layer binder that performs as well as or better than existing charge transport layer binders and is additionally capable of being coated from a solution containing an environmentally friendly solvent.
These and other objects are obtained by the present invention. In a first aspect, the present invention relates to a charge transport layer material for a photoreceptor comprising at least a bisphenol A-phthallic acid dichloride ester copolymer polycarbonate binder and at least one charge transport material dispersed in a solvent comprised of at least tetrahydrofuran.
In a second aspect of the invention, the invention relates to a charge transport layer of a photoreceptor comprising at least a bisphenol A-phthallic acid dichloride ester copolymer polycarbonate binder and at least one charge transport material.
In a third aspect of the invention, the invention relates to an image forming device comprising at least a photoreceptor and a charging device which charges the photoreceptor, wherein the photoreceptor comprises an optional anti-curl layer, a substrate, an optional hole blocking layer, an optional adhesive layer, a charge generating layer, a charge transport layer comprising at least a bisphenol A-phthallic acid dichloride ester copolymer polycarbonate binder and at least one charge transport material, and an optional overcoat layer.
By the use of the preferred polycarbonate resin binder as the charge transport layer binder in the present invention, a charge transport layer of an imaging member is achieved that has excellent hole transporting performance and wear resistance, and that is able to be coated onto the imaging member structure with an environmentally friendly solvent such as tetrahydrofuran.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In the present invention, the charge transport layer material for a photoreceptor comprises at least a bisphenol A-phthallic acid dichloride ester copolymer polycarbonate binder
Bergfjord, Sr. John A.
Carmichael Kathleen M.
Drappel Stephan V.
Maty David J.
Goodrow John
Oliff & Berridg,e PLC
Palazzo Eugene O.
Xerox Corporation
LandOfFree
Photoreceptor charge transport layer with a polycarbonate... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photoreceptor charge transport layer with a polycarbonate..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoreceptor charge transport layer with a polycarbonate... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2910091