Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-01-13
2001-02-20
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06191249
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophoto-graphic photoconductor comprising an electroconductive support, and a photoconductive layer formed thereon, comprising an aromatic polycarbonate resin as an effective component. In addition, the present invention also relates to the above-mentioned aromatic polycarbonate resin with charge transporting properties.
2. Discussion of Background
Recently organic photoconductors are used in many copying machines and printers. These organic photoconductors have a layered structure comprising a charge generation layer (CGL) and a charge transport layer (CTL) which are successively overlaid on an electroconductive support. The charge transport layer (CTL) is a film-shaped layer comprising a binder resin and a low-molecular-weight charge transport material (CTM) dissolved therein. The addition of such a low-molecular-weight charge transport material (CTM) to the binder resin lowers the intrinsic mechanical strength of the binder resin, so that the CTL film is fragile and has a low tensile strength. Such lowering of the mechanical strength of the CTL causes the wearing of the photoconductor or forms scratches and cracks in the surface of the photoconductor.
Although some vinyl polymers such as polyvinyl anthracene, polyvinyl pyrene and poly-N-vinylcarbazole have been studied as high-molecular-weight photo-conductive materials for forming a charge transporting complex for use in the conventional organic photo-conductor, such polymers are not satisfactory from the viewpoint of photosensitivity.
In addition, high-molecular-weight materials having charge transporting properties have been also studied to eliminate the shortcomings of the above-mentioned layered photoconductor. For instance, there are proposed an acrylic resin having a triphenylamine structure as reported by M. Stolka et al., in “J. Polym. Sci., vol 21, 969 (1983)”; a vinyl polymer having a hydrazone structure as described in “Japan Hard Copy '89 p. 67”; and polycarbonate resins having a triarylamine structure as disclosed in U.S. Pat. Nos. 4,801,517, 4,806,443, 4,806,444, 4,937,165, 4,959,288, 5,030,532, 5,034,296, and 5,080,989, and Japanese Laid-Open Patent Applications Nos. 64-9964, 3-221522, 2-304456, 4-11627, 4-175337, 4-18371, 4-31404, and 4-133065. However, any materials have not yet been put to practical use.
According to the report of “Physical Review B46 6705 (1992)” by M. A. Abkowitz et al., it is confirmed that the drift mobility of a high-molecular weight charge transporting material is lower than that of a low-molecular weight material by one figure. This report is based on the comparison between the photoconductor comprising a low-molecular weight tetraarylbenzidine derivative dispersed in the photoconductive layer and the one comprising a high-molecular polycarbonate having a tetraarylbenzidine structure in its molecule. The reason for this has not been clarified, but it is suggested that the photoconductor employing the high-molecular weight charge transporting material produces poor results in terms of the photosensitivity and the residual potential although the mechanical strength of the photoconductor is improved.
Conventionally known representative aromatic polycarbonate resins are obtained by allowing 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A) to react with a carbonate precursor material such as phosgene or diphenylcarbonate. Such polycarbonate resins made from bisphenol A are used in many fields because of their excellent characteristics, such as high transparency, high heat resistance, high dimensional accuracy, and high mechanical strength.
For example, this kind of polycarbonate resin is intensively studied as a binder resin for use in an organic photoconductor in the field of electrophoto-graphy. A variety of aromatic polycarbonate resins have been proposed as the binder resins for use in the charge transport layer of the layered photoconductor.
As previously mentioned, however, the mechanical strength of the aforementioned aromatic polycarbonate resin is decreased by the addition of the low-molecular-weight charge transporting material in the charge transport layer of the layered electrophotographic photoconductor.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to provide an electrophotographic photo-conductor free from the conventional shortcomings, which can show high photosensitivity and high durability.
A second object of the present invention is to provide an aromatic polycarbonate resin that is remarkably useful as a high-molecular-weight charge transporting material for use in an organic electrophotographic photoconductor.
The above-mentioned first object of the present invention can be achieved by an electrophotographic photoconductor comprising an electroconductive support, and a photoconductive layer formed thereon comprising as an effective component an aromatic polycarbonate resin having a repeat unit of formula (I):
wherein n is an integer of 5 to 5000; Ar
1
, Ar
2
, Ar
3
and Ar
4
, which may be the same or different, represent a bivalent aromatic hydrocarbon group which may have a substituent, or a bivalent heterocyclic group which may have a substituent; Ar
5
is an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent; and X is a bivalent aliphatic group, a bivalent cyclic aliphatic group, or
in which R
1
and R
2
are each independently an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a halogen atom; l and m are each independently an integer of 0 to 4; and p is an integer of 0 or 1, and when p=1, Y is a straight-chain, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO
2
—,
in which Z is a bivalent aliphatic hydrocarbon group; a is an integer of 0 to 20; b is an integer of 1 to 2000; and R
3
and R
4
are each independently an alkyl group which may have a substituent or an aromatic hydrocarbon group which may have a substituent.
In the above-mentioned photoconductor, the repeat unit of formula (I) may be represented by the following formula (IV):
wherein n, Ar
5
and X are the same as those previously defined in formula (I).
The first object of the present invention can also be achieved by an electrophotographic photoconductor comprising an electroconductive support, and a photoconductive layer formed thereon comprising as an effective component an aromatic polycarbonate resin having a repeat unit of formula (II) and a repeat unit of formula (III), with the composition ratio of the repeat unit of formula (II) to the repeat unit of formula (III) being in the relationship of 0<k/(k+j)≦1:
wherein k is an integer of 5 to 5000; j is an integer of 0 to 5000; Ar
1
, Ar
2
, Ar
3
and Ar
4
, which may be the same or different, represent a bivalent aromatic hydrocarbon group which may have a substituent, or a bivalent heterocyclic group which may have a substituent; Ar
5
is an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent; and X is a bivalent aliphatic group, a bivalent cyclic aliphatic group, or
in which R
1
and R
2
are each independently an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a halogen atom; l and m are each independently an integer of 0 to 4; and p is an integer of 0 or 1, and when p=1, Y is a straight-chain, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—,—S—, —S—, —SO—, —SO
2
—,
in which Z is a bivalent aliphatic hydrocarbon group; a is an integer of 0 to 20; b is an integer of 1 to 2000; and R
3
and R
4
are each independently an alkyl group which may have a substituent or an aromatic hydrocarbon group which may have a substituent.
In the above-mentioned photoconductor, the repeat unit of formula (II) may be represented by the following formula (V):
wherein k and Ar
5
are the same as
Adachi Chihaya
Anzai Mitsutoshi
Katayama Akira
Morooka Katsuhiro
Nagai Kazukiyo
Boykin Terressa M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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