Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Nitrogen-containing reactant
Reexamination Certificate
2001-10-02
2003-10-07
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Nitrogen-containing reactant
C528S373000, C528S398000, C525S328500, C428S690000, C428S917000, C250S462100
Reexamination Certificate
active
06630566
ABSTRACT:
The present invention relates to certain polymeric materials, and compositions containing them, which may be useful as charge transport materials. The invention also relates to processes for making these polymers and their use in devices such as electroreprographic devices and electroluminescent devices.
Polymers of the invention may be particularly useful in the field of electroreprography. Electroreprography is any process in which an image is reproduced by means of electricity and incident radiation, usually, electromagnetic radiation, more usually visible light. Electroreprography includes the technology of electrophotography which encompasses photocopying and laser printing technologies. Typically, in both a photocopier and a laser printer, a photo-conductive member is first charged in the dark (e.g. by applying a high voltage via a Corona discharge). Then a latent electrostatic image in charge is produced by partial exposure of the charged photo-conductive member (e.g. a drum or belt) to radiation (e.g. light). The radiation neutralises the charge to the exposed regions. The light source can either be reflected light from an illuminated image (photocopying) or from a laser which scans the photo-conductive member usually under instruction from a computer (laser printing). Once a latent image has been produced in charge, it is developed with toner, the toner is transferred onto a substrate (e.g. paper) and then fixed thereto (e.g. by heat) so that a visible image is obtained.
The photo-conductive member typically comprises a photo-conductor (e.g. an organic photo-conductor [“OPC”]) which must perform two different functions: generate a charge on exposure to the incident radiation; and transport the photo-generated charge to the surface. The unexposed regions of the photo-conductive member will retain their charge and form the latent image. It is usual to use different materials for each of these two processes and develop materials which are separately optimized for their ability to generate photo-induced charge (charge generating materials or “CGMs”) or their ability to transport charge (charge transport materials or “CTMs”). One aspect of the present invention is concerned with improvements in the field of CTMs.
The photo-conductor can be constructed as a single law or from a plurality of layers, for example from at least one charge generating layer (“CGL”) comprising the CGM and at least one separate charge transport layer (“CTL”) comprising the CTM.
An ideal photoconductor would be one where the material charges rapidly to a high value in the dark, retains the charge in the dark (i.e. exhibits no dark decay) and shows rapid total discharge on exposure to low-intensity illumination. The time taken for the charge-discharge cycle of a photo-conductor limits the maximum speed at which the latent image can be generated. Photo-conductive materials with improved electrical properties allow faster printing and copying.
The present invention relates to certain polymeric materials which may comprise triarylamine repeat units and which can offer improved properties as charge transport materials. Triarylamines are well known small molecule CTMs. Certain large molecule compounds and polymeric materials that comprise triarylamine moieties and/or repeat units are also known in the prior art, as described below.
DE 3610649 (BASF) discloses polymers of formula:
where ′n is from 1 to 100, and ′X is H or Br. These polymers are made from an Ullmann coupling of tri- and/or di-bromotriphenylamine monomers and are not end capped (i.e. are not treated with a material with acts as an end capping reagent positively to control the molecular weight of the chains during polymerisation). This reference only suggests the use of these polymers as effective electrical conductors if doped either chemically (e.g. with tris-p-bromophonylaminiumhexachloroantimonate) or electrochemically (e.g. by anodic oxidation with conducting salt anions). This acts as a disincentive for a reader of this document to use undoped triarylamine polymers as CTMs in electroreprography, particularly as this field of use is not mentioned in this patent. This document does not suggest that it might be desirable to control the properties of these polymers during polymerisation, or how this might be achieved.
EP 0669654-A (Toyo ink) (=U.S. Pat. No. 5,681,664) discloses a hole transport material which is a copolymer of formula:
H—A″—[B″—A″]
n
—B″—A″—H
where A″ is a aromatic amine moiety which may be a triarylamine and B″ is a C
4-7
alicyclic moiety which optionally may contain heteroatoms. This document teaches that these copolymers need the alicyclic moiety B″ to be an effective hole transport material and this would discourage a reader of this document from using polymers without this moiety as CTMs. These polymers are not intentionally end capped.
EP 0786106-A (Toyo ink) discloses light emitting compounds of formula:
where each of A
1−
to A
4−
is a substituted or unsubstituted aryl group having 6 to 16 carbon atoms, and each of R
1−
to R
B−
is independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group or a substituted or unsubstituted amino group, provided that adjacent substituents may form an aryl ring. These compounds are not polymers and there is no suggestion from this document to use polymers as CTMs.
EP 0827367-A (Xerox) disclose the use in electroluminescent (EL) devices of polynuclear amines of formula:
where ′R
1
to ′R
5
are aryl groups and ′A
1
and ′A
2
are biaryl groups. These compounds are monodisperse molecules which are prepared by direct synthesis (e.g. Ullmann coupling), not by polymerisation. These compounds are not polymers. Indeed this patent teaches explicitly that polymeric CTMs are disadvantageous compared to the above compounds, as Xerox state that, unlike polymers, these compounds can be used to prepare a CTL by vapour deposition (see page 2, lines 29 to 31).
JP-A-08(96)-040995, 040996 and 040997 (all Togo ink) are consecutively numbered patent publications each of which discloses certain compounds which comprise triphenylamine residues. The compounds in stated to have utility in OLEDs and electrophotosensors. These triarylamine derivatives are molecular compounds and are not end gapped polymeric materials.
JP-A-08(96)-259938 (Togo ink) describes hole transport materials (for use in electrophotography and OLEDs) which are compounds of the formula:
where: ′″R
1
to ′″R
14
are H, halogen, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted thioalkoxy, cyano, amino, mono- or di-substituted amino, hydroxy, mercapto, optionally substituted aryloxy, optionally substituted arylthio, optionally substituted carbocyclic aromatic ring group, optionally substituted heterocyclic aromatic ring group, optionally substituted heterocyclic group with neighbouring substituents optionally forming optionally substituted alicyclic ring, optionally substituted carbocyclic aromatic ring, optionally substituted heterocyclic aromatic ring, optionally substituted heterocyclic ring: and ′″n is 2 to 7. These molecules contain a saturated alicyclic or heterocyclic moiety, are not polymers and are not end capped.
U.S. Pat. No. 3,256,486 (Eastman Kodak) discloses doped linear polymers comprising triarylamine repeat units which have utility as photo-conductors in electrophotography where the polymer would perform the function of both the COM and CTM. This teaches away from the use of undoped linear polymers as a separate CTM in conjunction with a (different) CGM. The polymers disclosed are not end capped polymers and there is no suggestion that it would be desirable to control polymerisation or how this might be achieved.
U.S. Pat. No. 4,322,487 (Eastman Kodak): and Research Disclosure 19014 (Feb 1980); disc
Allen Joanne Victoria
Fergus Julie Anne
Leeming Stephen William
Morgan John Dylan
Thomas Mark
Avecia Limited
Truong Duc
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