Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
1995-03-23
2001-01-16
Rodee, Christopher D. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S078000, C430S059400
Reexamination Certificate
active
06174635
ABSTRACT:
DESCRIPTION
1. Field of the Invention
The present invention relates to photosensitive recording materials suitable for use in electrophotography.
2. Background of the Invention
In electrophotography photoconductive materials are used to form a latent electrostatic charge image that is developable with finely divided colouring material, called toner.
The developed image can then be permanently affixed to the photoconductive recording material, e.g. a photoconductive zinc oxide-binder layer, or transferred from the photoconductor layer, e.g. a selenium or selenium alloy layer, onto a receptor material, e.g. plain paper and fixed thereon. In electrophotographic copying and printing systems with toner transfer to a receptor material the photoconductive recording material is reusable. In order to permit rapid multiple printing or copying, a photoconductor layer has to be used that rapidly loses its charge on photo-exposure and also rapidly regains its insulating state after the exposure to receive again a sufficiently high electrostatic charge for a next image formation. The failure of a material to return completely to its relatively insulating state prior to succeeding charging/imaging steps is commonly known in the art as “fatigue”.
The fatigue phenomenon has been used as a guide in the selection of commercially useful photoconductive materials, since the fatigue of the photoconductive layer limits the copying rates achievable.
A further important property which determines the suitability of a particular photoconductive material for electrophotographic copying is its photosensitivity, which must be sufficiently high for use in copying apparatuses operating with the fairly low intensity light reflected from the original. Commercial usefulness also requires that the photoconductive layer has a spectral sensitivity that matches the spectral intensity distribution of the light source e.g. a laser or a lamp. This enables, in the case of a white light source, the reproduction of all the colours in balance.
Known photoconductive recording materials exist in different configurations with one or more “active” layers coated on a conducting substrate and include optionally an outermost protective layer. By “active” layer is meant a layer that plays a role in the formation of the electrostatic charge image. Such a layer may be the layer responsible for charge carrier generation, charge carrier transport or both. Such layers may have a homogeneous structure or heterogeneous structure.
Examples of active layers in said photoconductive recording material having a homogeneous structure are layers made of vacuum-deposited photoconductive selenium, doped silicon, selenium alloys and homogeneous photoconducting polymer coatings, e.g. of poly(vinylcarbazole) or polymeric binder(s) molecularly doped with an electron (negative charge carrier) transporting compound or a hole (positive charge carrier) transporting compound such as particular hydrazones, amines and heteroaromatic compounds sensitized by a dissolved dye, so that in said layers both charge carrier generation and charge carrier transport take place.
Examples of active layers in said photoconductive recording material having a heterogeneous structure are layers of one or more photosensitive organic or inorganic charge generating pigment particles dispersed in a polymer binder or polymer binder mixture in the presence optionally of (a) molecularly dispersed charge transport compound(s), so that the recording layer may exhibit only charge carrier generation properties or both charge carrier generation and charge transport properties.
According to an embodiment that may offer photoconductive recording materials with particularly low fatigue a charge generating and charge transporting layer are combined in contiguous relationship. Layers which serve only for the charge transport of charge generated in an adjacent charge generating layer are e.g. plasma-deposited inorganic layers, photoconducting polymer layers, e.g. on the basis of poly(N-vinylcarbazole) or layers made of low molecular weight organic compounds molecularly distributed in a polymer binder or binder mixture.
In order to form a photoconductive two layer-system with high photosensitivity to the incident light efficient charge generating substances are required that operate in conjunction with efficient charge transport substances.
Examples of preferred polymeric positive hole charge carrier transporting substances are poly(N-vinylcarbazole), N-vinylcarbazole copolymers, polyvinyl anthracene and the condensation products of an aldehyde with two or more 1,2-dihydroquinoline molecules as described e.g. in U.S. Pat. No. 5,043,238.
Preferred non-polymeric materials for positive charge transport are
a) hydrazones e.g. a p-diethylaminobenzaldehyde diphenyl hydrazone as described in U.S. Pat. No. 4,150,987; and other hydrazones described in U.S. Pat. No. 4,423,129: U.S. Pat. No. 4,278,747, U.S. Pat. No. 4,365,014, EP 448,843 A and EP 452,569 A, e.g. T 191 from Takasago having the following structure:
b) aromatic amines e.g. N,N′-diphenyl, N,N-bis-m-tolyl benzidine as described in U.S. Pat. No. 4,265,990, tris(p-tolyl)amine as described in U.S. Pat. No. 3,180,730:
1,3,5-tris(aminophenyl)benzenes as described in U.S. Pat. No. 4,923,774; 3,5 diarylaniline derivatives as described in EP 534,514 A and triphenyloxazole derivatives as described in EP 534,005 A;
c) heteroaromatic compounds e.g. N-(p-aminophenyl) carbazoles as described in U.S. Pat. No. 3,912,509 and dihydroquinoline compounds as described in U.S. Pat. No. 3,832,171, U.S. Pat. No. 3,830,647, U.S. Pat. No. 4,943,502, U.S. Pat. No. 5,043,238, EP 452,569 A and EP 462,327 A e.g.
d) triphenylmethane derivatives as described for example in U.S. Pat. No. 4,265,990;
e) pyrazoline derivatives as described for example in U.S. Pat. No. 3,837,851;
f) stilbene derivatives as described for example in Japanese Laid Open Patent Application (JL-0P) 198,043/83.
Preferred non-polymeric materials for negative charge transport are
a) dicyanomethylene and cyanoalkoxycarbonyl methylene condensates with aromatic ketones such as 9-dicyanomethylene-2,4,7-trinitro-fluorenone (DTF); 1-dicyanomethylene-indan-1-ones as described in EP 537,808 A with the formula:
wherein R
1
and R
2
have the same meaning as described in said published EP application; compounds with the formula:
wherein A is a spacer linkage selected from the group consisting of an alkylene group including a substituted alkylene group, an arylene group including a substituted arylene group; S is sulphur, and B is a member selected from the group consisting of an alkyl group including a substituted alkyl group, and an aryl group including a substituted aryl group as disclosed e.g. in U.S. Pat. No. 4,546,059 such as:
and 4-dicyanomethylene 1,1-dioxo-thiopyran-4-one derivatives as disclosed in U.S. Pat. No. 4,514,481 and U.S. Pat. No. 4,968,813 e.g.
b) derivatives of malononitrile dimers as described in EP 534,004 A;
c) nitrated fluorenones such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitrofluorenone;
d) dicyanofluorene carboxylate derivatives as described in U.S. Pat. No. 4,562,132;
e) 1,1,2-tricyanoethylene derivatives.
Useful charge carrier generating pigments (CCM's) belong to one of the following classes:
a) perylimides, e.g. C.I. 71 130 (C.I.=Colour Index) described in DBP 2 237 539;
b) polynuclear quinones, e.g. anthanthrones such as C.I. 59 300 described in DBP 2 237 678;
c) quinacridones, e.g. C.I. 46 500 described in DBP 2 237 679;
d) naphthalene 1,4,5,8-tetracarboxylic acid derived pigments including the perinones, e.g. Orange GR. C.I. 71 105 described in DBP 2 239 923;
e) tetrabenzoporphyrins and tetranaphthaloporphyrins, e.g.
H
2
-phthalocyanine in X-crystal form (X—H
2
Pc) described in U.S. Pat. No. 3,357,989, metal phthalocyanines, e.g. CuPc C.I. 74 160 described in DBP 2 239 924, indium phthalocyanine described in U.S. Pat. No. 4,713,312 and tetrabenzoporphyrins described in EP 428,214 A; and naphthalocyanines having siloxy groups bonded to the central
De Meutter Stefaan
Kaletta Bernd
Terrell David
Agfa-Gevaert N.V.
Breiner & Breiner
Rodee Christopher D.
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