Photoreceptor Charge Transport Layer Composition for Wear and Crack Resistance
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Solution Overview
Problem
Existing electrophotographic photoreceptors face issues with wear resistance and cracking resistance, particularly when the charge transport layer is composed of polyester resin or does not contain terphenyl, leading to surface degradation and image defects.
Innovation Solution
The charge transport layer is formulated with a specific polyester resin containing diol units and a biphenyl skeleton, along with a compound represented by Formula (T), which enhances cohesion and resistance to wear and cracking by incorporating bulky groups that create molecular spaces and increase interaction between resin and compound, thereby improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the charge transport layer is composed of polyester resin without specific modifications, then the manufacturing process is simple, but the wear resistance and cracking resistance are insufficient
Solution Approach 1:
The patent uses a composite resin system combining polyester resin with specific diol units (P1-P6), a unit including a biphenyl skeleton, and compound (T) with formula (T). This composite material approach provides synergistic effects where each component contributes to overall wear resistance and cracking resistance, resolving the contradiction between simplicity and performance by creating a optimized composite rather than using a single modified resin
Solution Approach 2:
The patent introduces specific functional units at localized positions within the resin structure - the diol units (P1-P6) provide flexibility and crack resistance, the biphenyl skeleton unit provides structural rigidity, and compound (T) with bulky groups provides wear resistance. This local quality assignment allows different parts of the resin system to perform specific functions, achieving high durability without overly complicating the overall composition
2Reliability
If the charge transport layer does not contain terphenyl or specific compound (T), then the resin composition is simpler, but the cohesion and resistance to surface degradation are reduced
Solution Approach 1:
The patent changes the chemical parameters of the resin system by incorporating compound (T) with specific formula (T) containing bulky groups. This parameter change - the introduction of specific molecular structures with defined chemical composition - enhances cohesion and surface degradation resistance. The bulky groups in compound (T) create molecular spaces and increase interaction between resin and compound, providing reliable protection against surface degradation while maintaining manageable composition complexity through targeted chemical selection
3Strength
If the polyester resin contains fluorine atoms in end groups, then the resin may have different processing properties, but the wear resistance and cracking resistance are lower
Solution Approach 1:
The patent changes the chemical parameter of the polyester resin by specifying that end groups do not include fluorine atoms. This parameter change - removing fluorine from the end group composition - directly improves wear resistance and cracking resistance. The specification maintains ease of manufacture by providing clear compositional guidelines for the polyester resin (1) including the specific diol units and biphenyl skeleton unit, allowing standard manufacturing processes to be used while achieving superior durability
Data Source
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AI summary
An electrophotographic photoreceptor includes a conductive base body and a multilayered photosensitive layer disposed on the conductive base body and including a charge generation layer and a charge transport layer, wherein the charge transport layer is an uppermost surface layer and contains a charge transport material, a polyester resin, and a compound (T) represented by Formula (T) below, the polyester resin includes a polyester resin (1) including at least one selected from the group consisting of a diol unit (P1) represented by Formula (P1), a diol unit (P2) represented by Formula (P2), a diol unit (P3) represented by Formula (P3), a diol unit (P5) represented by Formula (P5), and a diol unit (P6) represented by Formula (P6), the polyester resin (1) further includes a unit including a biphenyl skeleton, and end groups of the polyester resin (1) do not include fluorine atoms, Formula (T) ArT1-LT1-ArT2 in Formula (T), ArT1 is an optionally substituted naphthyl group or an optionally substituted biphenyl group, LT1 is a single bond or an ether bond, and ArT2 is an optionally substituted aryl group having 6 or more and 12 or less carbon atoms or an optionally substituted aralkyl group having 7 or more and 20 or less carbon atoms, in Formula (P1), Rb101 is a branched alkyl group having 4 or more and 20 or less carbon atoms, Rb201 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb401, Rb501, Rb801, and Rb901 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (P2), Rb102 is a linear alkyl group having 4 or more and 20 or less carbon atoms, Rb202 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb402, Rb502, Rb802, and Rb902 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (P3), Rb113 and Rb213 are each independently a hydrogen atom, a linear alkyl group having 1 or more and 3 or less carbon atoms, an alkoxy group having 1 or more and 4 or less carbon atoms, or a halogen atom, d is an integer of 7 or more and 15 or less, and Rb403, Rb503, Rb803, and Rb903 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (P5), Ar105 is an aryl group having 6 or more and 12 or less carbon atoms or an aralkyl group having 7 or more and 20 or less carbon atoms, Rb205 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb405, Rb505, Rb805, and Rb905 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, and in Formula (P6), Rb116 and Rb216 are each independently a hydrogen atom, a linear alkyl group having 1 or more and 3 or less carbon atoms, an alkoxy group having 1 or more and 4 or less carbon atoms, or a halogen atom, e is an integer of 4 or more and 6 or less, and Rb406, Rb506, Rb806, and Rb906 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom.