Electrophotographic photoreceptor with polyester resin in photosensitive layer

1. An electrophotographic photoreceptor comprising an electroconductive substrate and a photosensitive layer formed thereon, wherein the photosensitive layer contains a polyester resin consisting of a repeating ester structure consisting of at least one bivalent phenol residue having formula (1) and at least one of an aromatic dicarboxylic acid residue having formula (2):

wherein R 1 and R 5 are each a methyl group and R 2 to R 4 are hydrogen atoms.

2. The electrophotographic photoreceptor according to claim 1 , wherein the aromatic dicarboxylic acid residue represented by formula (2) is a terephthaloyl acid residue.

3. The electrophotographic photoreceptor according to claim 1 , wherein the polyester resin has a viscosity average molecular weight ranging from 15,000 to 100,000.

4. The electrophotographic photoreceptor according to claim 1 , wherein the photosensitive layer contains a compound represented by formula (7):

wherein each of Ar 1 to Ar 4 , which are independent of one another, represents an arylene group which optionally is substituted, or a bivalent heterocyclic group which optionally is substituted, each of m 1 and m 2 , which are independent of one another, represents 0 or 1, each of Ar 5 , when m 1 =0, and Ar 6 , when m 2 =0, represents an alkyl group, which optionally is substituted, an aryl group, which optionally is substituted, or a monovalent heterocyclic group, which optionally is substituted, each of Ar 5 , when m 1 =1, and Ar 6 , when m 2 =1, represents an alkylene group, which optionally is substituted, an arylene group, which optionally is substituted, or a bivalent heterocyclic group, which is optionally is substituted, Q represents a direct bond or a bivalent residue, each of R 6 to R 13 , which are independent of one another, represents hydrogen, an alkyl group, which optionally is substituted, an arylgroup, which optionally is substituted, or a heterocyclic group, and each of n 1 to n 4 , which are independent of one another, represents an integer ranging from 0 to 4, provided that Ar 1 to Ar 6 may be mutually bonded to form a cyclic structure.

5. An electrophotographic photoreceptor comprising an electroconductive substrate and a photosensitive layer formed thereon, wherein the photosensitive layer contains a polyester resin having

(A) a repeating ester structure of a bivalent phenol residue having formula (1) and at least one aromatic dicarboxylic acid residue having formula (2):

wherein R 1 and R 5 are each a methyl group and R 2 to R 4 are hydrogen atoms, and

(B) a repeating ester structure comprising a bivalent phenol residue having formula (3) below and an aromatic dicarboxylic acid residue having formula (2):

6. The electrophotographic photoreceptor according to claim 5 , wherein the bivalent phenol residue represented by formula (3) has a structure selected from the structures represented by the following formulas (4), (5) and (6), and the polyester resin has at least two types of repeating ester structures comprising such a bivalent phenol residue and an aromatic dicarboxylic acid residue having formula (2):

7. The electrophotographic photoreceptor according to claim 6 , wherein at least one bivalent phenol residue represented by formula (3) has a structure represented by formula (4).

8. An electrophotographic photoreceptor comprising an electroconductive substrate and a photosensitive layer formed thereon, wherein the photosensitive layer contains a polyester resin having (A) a repeating ester structure of a bivalent phenol residue having formula (1) and at least one aromatic dicarboxylic acid residue having formula (2),

wherein R 1 and R 5 are each a methyl group and R 2 to R 4 are hydrogen atoms,

and (B) a repeating ester structure of terephthalic acid and a bivalent phenol residue having the following formula: