Photoreceptor

Claim 2

In a photoreceptor comprising an electroconductive base that has a carrier generation layer formed thereon which is overlaid with a carrier transport layer, the improvement wherein said carrier transport layer comprises at least two constituent layers, the weight ratio of the content of the carrier transport material to the binder material in a constituent layer which is closer to said electroconductive base is higher than the weight ratio of the content of the carrier transport material to the binder material in a constituent layer which is more remote from said electroconductive base, and the binder in the outermost constituent layer of said carrier transport layer contains a polycarbonate having as the principal recurring unit a structural unit represented by the following general formula (I) and/or a structural unit represented by the following general formula (II): (where R¹ and R² each is a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted carbocyclic group, or a substituted or unsubstituted aromatic group, provided that at least one of R¹ and R² is a "bulky" group; and R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ each is a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted carbocyclic group); (where R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ each is name as defined above; Z is the atomic group necessary to form a substituted or unsubstituted carbon ring or a substituted or unsubstituted heterocyclic ring).

Claim 3

A photoreceptor according to claim 1 wherein the ratio of the content of the carrier transport material to binder material in the outermost constituent layer of said carrier transport layer is not higher than 70 wt%.

Claim 4

A photoreceptor according to claim 1 wherein the weight ratio of the content of the carrier transport material to binder material in the outermost constituent layer of said carrier transport layer is 5 - 70 wt%.

Claim 5

A photoreceptor according to claim 1 wherein the weight ratio of the content of the carrier transport material to binder material in a constituent layer of said carrier transport layer which is the closest to the electroconductive base is at least 30 wt%.

Claim 6

A photoreceptor according to claim 1 wherein the ratio of the content of the carrier transport material to binder material in a constituent layer of said carrier transport layer which is the closest to the electroconductive base is 30 - 300 wt%.

Claim 7

A photoreceptor according to claim 1 wherein the ratio of the content of the carrier transport material to binder material in the outermost constituent layer of said carrier transport layer differs by at least 1.0 wt% from the ratio of the content of the carrier transport material to binder material in a constituent layer which is the closest to the electroconductive base.

Claim 8

A photoreceptor according to claim 1 wherein R¹ and R² in said general formula (I) represent different groups, or they are bound asymmetrically if they are of the same group.

Claim 9

A photoreceptor according to claim 1 wherein at least one of R¹ and R² in said general formula (I) is a bulky group having at least 3 carbon atoms.

Claim 10

A photoreceptor according to claim 8 wherein at least one of said R¹ and R² is a member selected from among the following groups: (1) where R¹¹ is a hydrogen atom, an alkyl group such as methyl, or an alkyl ester group represented by CH₂) m COOR (where R is an alkyl group, and m ≧ 1); (2) (3) an alkyl group represented by -C m H 2m+1 (m ≧ 4); and (4) an alkyl ester group represented by CH₂) m COOR¹² (where R¹² is an alkyl group, and m ≧ 2).

Claim 11

A photoreceptor according to claim 1 wherein each of R³ - R¹⁰ in said general formulas (I) and (II) is at least one member selected from the group consisting of a hydrogen atom, a halogen atom, a methyl group and a cyclohexyl group.

Claim 12

A photoreceptor according to claim 1 wherein Z in the general formula (II) forms a 5- or 6-membered carbon ring or heterocyclic ring.

Claim 13

A photoreceptor according to claim 1 wherein the number of repetitions of the structural unit represented by said general formula (I) or (II) is from 10 to 5000.

Claim 14

A photoreceptor according to claim 1 wherein the number of repetitions of the structural unit represented by said general formula (I) or (II) is from 5o to 2000.

Claim 15

A photoreceptor according to claim 1 wherein said polycarbonate has at least a structural unit represented by said general formula (II).

Claim 16

A photoreceptor according to claim 11 wherein R³ - R¹⁰ in said general formula (II) are each a hydrogen atom and Z is the atomic group necessary to form a cyclohexylidene group.

Claim 17

A photoreceptor according to claim 1 wherein said carrier transport material is at least one of the members represented by the following general formulas (III) - (X): (where R¹³ is a substituted or unsubstituted aryl group; R¹⁴ is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an amino group, a hydroxyl group or a substituted amino group; and R¹⁵ is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group); (where R¹⁶ and R¹⁷ each is a hydrogen atom or a halogen atom; R¹⁸ and R¹⁹ each is a substituted or unsubstituted aryl group; and Ar¹ is a substituted or unsubstituted arylene group); (where R²⁰ is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group; R²¹ is a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group; Q is a hydrogen atom, a halogen atom, an alkyl group, a substituted amino group, an alkoxy group or a cyano group; and p is an integer of 0 or 1); (where R²² is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group; R²³ is a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group; X′₂ is a hydrogen atom, a halogen atom, an alkyl group, a substituted amino group, an alkoxy group or a cyano group; and q is an integer of 0 or 1); (where ℓ is an integer of 0 or 1; R²⁴, R²⁵ and R²⁶ each is a substituted or unsubstituted aryl group; R²⁷ and R²⁸ each is a hydrogen atom, an alkyl group having 1 - 4 carbon atoms, a substituted or unsubstituted aryl or aralkyl group, provided that R²⁷ and R²⁸ are not a hydrogen atom at the same time, and when ℓ is 0, R²⁷ is not a hydrogen atom); (where R²⁹ and R³⁰ each is a substituted or unsubstituted alkyl or phenyl group, with the substituent being an alkyl, alkoxy or phenyl group; R³¹ is a substituted or unsubstituted phenyl, naphthyl, anthryl, fluorenyl or heterocyclic group, with the substituent being an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group or a phenyl group; R 31′ is a hydrogen atom, a substituted or unsubstituted alkyl or phenyl group; and R³², R³³, R³⁴ and R³⁵ each is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or an alkylamino group); (where Ar² and Ar³ each is a substituted or unsubstituted phenyl group, with the substituent being a halogen atom, an alkyl group, a nitro group or an alkoxy group; and Ar⁴ is a substituted or unsubstituted phenyl, naphthyl, anthryl, fluorenyl or heterocyclic group, with the substituent being an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an aryloxy group, an aryl group, an amino group, a nitro group, a piperidino group, a morpholino group, a naphthyl group, an anthryl group or a substituted amino group, provided that the last-­mentioned substituted amino group has an acyl, alkyl, aryl or aralkyl group as the substituent); (where D is a substituted or unsubstituted phenyl group or a substituted or unsubstituted carbazolyl group, as specifically illustrated by where R³⁶, R³⁷, R³⁸, R³⁹ and R⁴⁵ each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group or a substituted or unsubstituted aryl group; and R⁴⁰, R⁴¹, R⁴², R⁴³, R⁴⁴ and R⁴⁶ each represents an alkyl group, an alkoxy group, a halogen atom, etc.)

Claim 18

A photoreceptor according to claim 1 wherein the carrier generation material contained in said carrier generation layer is a polycyclic quinone pigment or a bisazo pigment.

Claim 19

A photoreceptor according to claim 17 wherein said polycyclic quinone pigment is anthanthrone pigment represented by the following general formula (XI): where X is a halogen atom, a nitro group, a cyano group, an acyl group or a carboxyl group; n is an integer of 0 to 4; and m is an integer of 0 to 6.

Claim 20

A photoreceptor according to claim 17 wherein said bisazo pigment is fluorenylidene pigment represented by the following general formula (XVa): where R⁵⁵ and R⁵⁶ each is an alkyl group, an alkoxy group or an aryl group; R⁵⁷, R⁵⁸, R⁵⁹, R⁶⁰, R⁶¹ and R⁶² each is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an amino group, a hydroxyl group or an aryl group; and A˝ is a substituted or unsubstituted aryl group.

Claim 21

A photoreceptor according to claim 17 wherein said bisazo pigment is a fluorenone pigment represented by the following general formula (XVI): where X¹ and X² each is a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a nitro group, a cyano group, a hydroxyl group or a substituted or unsubstituted amino group, provided that at least one of X¹ and X² is a halogen atom; p and q each represents an integer of 0, 1 or 2, provided that p and q are not zero at the same time and that when p is 2, X¹ may be the same or different groups, and that when q is 2, X² may be the same or different groups; and A is a group represented by the following general formula (XVII): (where Ar⁸ is an aromatic carbocyclic or heterocyclic group having at least one fluorinated hydrocarbon group; Z is the nonmetallic atomic group necessary to form a substituted or unsubstituted aromatic carbon ring or a substituted or unsubstituted aromatic heterocyclic ring); m and n each represents an integer of 0, 1 or 2, provided that m and n are not zero at the same time.

Claim 22

A photoreceptor according to claim 1 wherein a constituent layer of said carrier transport layer that is closer to the electroconductive base and that is adjacent to the outermost constituent layer of said carrier transport layer contains a bisphenol A type polycarbonate as a binder.

Claim 23

A photoreceptor according to claim 1 wherein the binder resin contained in a constituent layer of said carrier transport layer that is closer to the electroconductive base and that is adjacent to the outermost constituent layer of said carrier transport layer is hardly soluble with respect to the solvent used to coat said outermost constituent layer.

Claim 24

A photoreceptor according to claim 1 wherein a constituent layer of said carrier transport layer that is the closest to the electroconductive base is formed by dip coating, and a constituent layer of said carrier transport layer that is adjacent to said constituent layer and that is more remote from the electroconductive base is formed by spray coating.

Claim 25

A photoreceptor according to claim 1 wherein a constituent layer of said carrier transport layer which is the closest to the conductive base has a thickness of 5 - 50 µm.

Claim 26

A photoreceptor according to claim 1 wherein a constituent layer of said carrier transport layer which is the closest to the electroconductive base has a thickness of 5 - 30 µm.

Claim 27

A photoreceptor according to claim 1 wherein the outermost constituent layer of said carrier transport layer has a thickness of 0.1 - 30 µm.

Claim 28

A photoreceptor according to claim 1 wherein the outermost constituent layer of said carrier transport layer has a thickness of 0.5 - 10 µm.

Claim 29

A photoreceptor according to claim 1 wherein said carrier generation layer has a thickness of 0.01 - 10 µm.

Claim 30

A photoreceptor according to claim 1 wherein said carrier generation layer has a thickness of 0.1 - 5 µm.