Electrophotographic photosensitive member, process cartridge and electrophotographic apparatus having the electrophotographic photosensitive member

A process cartridge comprising:

• an electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means;
• said electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer containing a charge transporting material and a charge generating material, said charge generating material comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:
• ##STR35## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR36## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR37## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR38## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR39## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.11, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

An electrophotographic apparatus comprising:

• an electrophotographic photosensitive member, charging means, image exposing means, developing means, and transfer means,
• said electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer containing a charge transporting material and a charge generating material, said charge generating material comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:
• ##STR40## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR41## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR42## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR43## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR44## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer comprising a charge transport layer and a charge generation layer, said charge generation layer comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:

• ##STR45## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR46## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR47## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR48## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR49## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

A process cartridge comprising:

• an electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means;
• said electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer comprising a charge transport layer and a charge generation layer, said charge generation layer comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:
• ##STR50## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR51## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR52## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR53## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR54## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

An electrophotographic apparatus comprising:

• an electrophotographic photosensitive member, charging means, image exposing means, developing means, and transfer means,
• said electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer comprising a charge transport layer and a charge generation layer, said charge generation layer comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:
• ##STR55## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR56## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR57## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR58## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR59## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer comprising at least one layer, said one layer containing a charge transport material and a charge generating material, said charge generating material comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:

• ##STR60## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR61## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR62## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR63## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR64## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

A process cartridge comprising:

• an electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means;
• said electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer comprising at least one layer, said one layer containing a charge transport material and a charge generating material, said charge generating material comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:
• ##STR65## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR66## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR67## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR68## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR69## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.

An electrophotographic apparatus comprising:

• an electrophotographic photosensitive member, charging means, image exposing means, developing means, and transfer means,
• said electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer on said conductive substrate, said photosensitive layer comprising at least one layer, said one layer containing a charge transport material and a charge generating material, said charge generating material comprising an azo pigment represented by at least one formula selected from the group consisting of formulas (1), (2), (3), (4) and (5) below:
• ##STR70## wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, and Cp.sub.1, Cp.sub.2 and Cp.sub.3 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR71## wherein Ar.sub.4 and Ar.sub.5 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.1 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.4, Cp.sub.5 and Cp.sub.6 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR72## wherein R.sub.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.6 and Ar.sub.7 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.2 is a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.7, Cp.sub.8 and Cp.sub.9 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR73## wherein R.sub.2 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.8 is the same or different and is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, A.sub.3 and A.sub.4 are the same or different and are each a residual group required to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring with the carbon atoms in the formula above, and Cp.sub.10, Cp.sub.11 and Cp.sub.12 are the same or different and are each a coupler residual group having a phenolic hydroxyl group:
• ##STR74## wherein R.sub.3 is a hydrogen atom, a substituted or unsubstituted alkyl group or a cyano group, Ar.sub.9, Ar.sub.10 and Ar.sub.11 are the same or different and are each a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Cp.sub.13, Cp.sub.14 and Cp.sub.15, are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and m, n and p are the same or different and are each zero or a positive integer wherein m, n and p are not simultaneously zero.