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IMPROVED SUBSTRATES FOR ORGANIC PHOTOCONDUCTORS

IP.com Disclosure Number: IPCOM000027037D
Original Publication Date: 1994-Dec-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 126K

Publishing Venue

Xerox Disclosure Journal

Abstract

Photoconductors for electrophotographic imaging processes can be prepared by applying an organic photoconductive material to a substrate of the desired size and shape, such as a drum or a belt. One method for preparing suitable substrates for organic photoconductors entails a centrifugal spin casting process, wherein a stream of high viscosity liquid monomer is delivered into a cylindrical mold which is spinning at high speed (about 105 revolutions per minute, for example). Rotation of the mold is maintained while the viscous monomer flows out to a uniform thickness inside the mold as a result of centrifugal force. Thereafter, the mold is heated to induce thermal crosslinking and/or polymerization of the monomer, thereby converting it to a solid cylindrical tube. The finished substrate tube is then released from the mold.

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XEROX DISCLOSURE JOURNAL

IMPROVED SUBSTRATES FOR Proposed Classification ORGANIC PHOTOCONDUCTORS US. C1.430/127 Stuart B. Berger
5/00 Int. John M. Hammond C1. G03g

Photoconductors for electrophotographic imaging processes can be prepared by applying an organic photoconductive material to a substrate of the desired size and shape, such as a drum or a belt. One method for preparing suitable substrates for organic photoconductors entails a centrifugal spin casting process, wherein a stream of high viscosity liquid monomer is delivered into a cylindrical mold which is spinning at high speed (about 105 revolutions per minute, for example). Rotation of the mold is maintained while the viscous monomer flows out to a uniform thickness inside the mold as a result of centrifugal force. Thereafter, the mold is heated to induce thermal crosslinking and/or polymerization of the monomer, thereby converting it to a solid cylindrical tube. The finished substrate tube is then released from the mold.

This process has some disadvantages related to the high viscosity (frequently greater than 106 centipoise) of the liquid monomer. It is dificult to pump the monomer into the mold, and, more importantly, the monomer may fail to flow out well into the smooth, uniform film needed for subsequent curing into a homogeneous solid polymer substrate. The use of organic liquid solvents to reduce monomer liquid viscosity is not satisfactory because the solvent cannot be evaporated from the finished substrate quickly enough to enable economical manufacturing throughput. In addition, residual solvent in the substrate can have adverse effects on photoconductor performance and may also have adverse environmental and/or safety effects. The use of heat as a means for reducing monomer liquid viscosity is also unsatisfactory because heating of the thermosetting monomer during liquid delivery into the mold can cause premature curing, resulting in a viscosity increase.

These disadvantages can be avoided by the use of supercritical carbo...