# US 8,771,909 B2 · Electrophotographic photoconductor, image forming apparatus, and process cartridge

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- Number: US 8,771,909 B2
- Document ID: US8771909B2
- Status: Granted
- Kind: B2
- Application number: 13/670,022
- Filed: 2012-11-06
- Published: 2013-05-16
- Granted: 2014-07-08
- Earliest claimed: 2011-11-15
- Assignees: Ricoh Company, Ltd.
- Applicants: Yuusuke Koizuka; Yuuji Tanaka; Kazukiyo Nagai; Tetsuro Suzuki
- Inventors: Yuusuke Koizuka; Yuuji Tanaka; Kazukiyo Nagai; Tetsuro Suzuki
- Web page: https://patentgrep.com/patent/US8771909B2

## CPC

- G03G 15/75: {Details relating to xerographic drum, band or plate, e.g. replacing, testing (electrographic recording members per se G03G5/00)}
- G03G 5/0589: {Macromolecular compounds characterised by specific side-chain substituents or end groups}
- G03G 5/0592: {Macromolecular compounds characterised by their structure or by their chemical properties, e.g. block polymers, reticulated polymers, molecular weight, acidity}
- G03G 5/06144: {diamine}
- G03G 5/14704: {comprising inorganic material}
- G03G 5/14769: {Other polycondensates comprising nitrogen atoms with or without oxygen atoms in the main chain}
- G03G 5/14786: {Macromolecular compounds characterised by specific side-chain substituents or end groups}
- G03G 5/14791: {Macromolecular compounds characterised by their structure, e.g. block polymers, reticulated polymers, or by their chemical properties, e.g. by molecular weight or acidity}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An electrophotographic photoconductor including: an electrically conductive substrate; and at least a photoconductive layer on the electrically conductive substrate, wherein the electrophotographic photoconductor includes an uppermost surface layer, and the uppermost surface layer includes an inorganic filler, an acidic disperser and a three-dimensionally crosslinked polymer, wherein the three-dimensionally crosslinked polymer is formed through polymerization among compounds each containing a charge transporting compound and three or more [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups where the charge transporting compound has one or more aromatic rings and the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups are bound to the aromatic rings of the charge transporting compound, and wherein the polymerization proceeds after some of the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups have been partially cleaved and eliminated with an acid catalyst.

## Claims

### Claim 1

An electrophotographic photoconductor comprising:
an electrically conductive substrate; and
at least a photoconductive layer on the electrically conductive substrate,
wherein the electrophotographic photoconductor comprises an uppermost surface layer, and the uppermost surface layer comprises an inorganic filler, an acidic disperser and a three-dimensionally crosslinked polymer,
wherein the three-dimensionally crosslinked polymer is formed through polymerization among compounds each containing a charge transporting compound and three or more [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups where the charge transporting compound has one or more aromatic rings and the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups are bound to the aromatic rings of the charge transporting compound, and
wherein the polymerization proceeds after some of the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups have been partially cleaved and eliminated with an acid catalyst.

### Claim 2 (depends on 1)

The electrophotographic photoconductor of claim 1, wherein the acidic disperser is a polycarboxylic acid.

### Claim 3 (depends on 1)

The electrophotographic photoconductor of claim 1, wherein the inorganic filler is a metal oxide.

### Claim 4 (depends on 3)

The electrophotographic photoconductor of claim 3, where the metal oxide is titanium oxide or alumina or both thereof.

### Claim 5 (depends on 1)

The electrophotographic photoconductor of claim 1, wherein the compound containing a charge transporting compound and three or more [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups where the charge transporting compound has one or more aromatic rings and the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups are bound to the aromatic rings of the charge transporting compound is a compound represented by the following General Formula (1):
where X1 is a C1-C4 alkylene group, a C2-C6 alkylidene group, a divalent group formed of two C2-C6 alkylidene groups bonded together via a phenylene group, or an oxygen atom, and Ar1, Ar2, Ar3, Ar4, Ar5 and Ar6 each are a C6-C18 divalent aromatic hydrocarbon group which may have an alkyl group as a substituent.

### Claim 6 (depends on 5)

The electrophotographic photoconductor of claim 5, wherein the compound represented by the General Formula (1) is a compound represented by the following General Formula (1-1):
where X2 is —CH2—, —CH2CH2—, —C(CH3)2-Ph-C(CH3)2—, —C(CH2)5— or —O—, where Ph is a phenylene group; R1, R2, R3, R4, R5 and R6, which may be the same or different, each are a hydrogen atom, a methyl group or an ethyl group; and o, p, q, r, s and t each are an integer of 1 to 4.

### Claim 7 (depends on 1)

The electrophotographic photoconductor of claim 1, wherein the photoconductive layer comprises a charge generation layer, a charge transport layer and a crosslinked charge transport layer disposed in this order on the electrically conductive substrate, and the crosslinked charge transport layer is the uppermost surface layer.

### Claim 8

An image forming apparatus comprising:
an electrophotographic photoconductor;
a charging unit configured to charge a surface of the electrophotographic photoconductor;
an exposing unit configured to expose the charged surface of the electrophotographic photoconductor to light to form a latent electrostatic image;
a developing unit configured to develop the latent electrostatic image with a toner to form a visible image;
a transfer unit configured to transfer the visible image onto a recording medium; and
a fixing unit configured to fix the transferred visible image on the recording medium,
wherein the electrophotographic photoconductor comprises:
an electrically conductive substrate; and
at least a photoconductive layer on the electrically conductive substrate,
wherein the electrophotographic photoconductor comprises an uppermost surface layer, and the uppermost surface layer comprises an inorganic filler, an acidic disperser and a three-dimensionally crosslinked polymer,
wherein the three-dimensionally crosslinked polymer is formed through polymerization among compounds each containing a charge transporting compound and three or more [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups where the charge transporting compound has one or more aromatic rings and the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups are bound to the aromatic rings of the charge transporting compound, and
wherein the polymerization proceeds after some of the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups have been partially cleaved and eliminated with an acid catalyst.

### Claim 9

A process cartridge comprising:
an electrophotographic photoconductor; and
at least one unit selected from the group consisting of a charging unit, an exposing unit, a developing unit, a transfer unit, a cleaning unit and a charge-eliminating unit,
wherein the process cartridge is detachably mounted to a main body of an image forming apparatus, and
wherein the electrophotographic photoconductor comprises:
an electrically conductive substrate; and
at least a photoconductive layer on the electrically conductive substrate,
wherein the electrophotographic photoconductor comprises an uppermost surface layer, and the uppermost surface layer comprises an inorganic filler, an acidic disperser and a three-dimensionally crosslinked polymer,
wherein the three-dimensionally crosslinked polymer is formed through polymerization among compounds each containing a charge transporting compound and three or more [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups where the charge transporting compound has one or more aromatic rings and the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups are bound to the aromatic rings of the charge transporting compound, and
wherein the polymerization proceeds after some of the [(tetrahydro-2H-pyran-2-yl)oxy]methyl groups have been partially cleaved and eliminated with an acid catalyst.