JP2005241974A - Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the difference in glass transition temperature between a charge transport material and a binder resin, and to form a charge transport layer with a specific binder resin, thereby providing high mechanical strength, high wear resistance, and good electrophotography. It is an object to provide an electrophotographic photosensitive member having characteristics, that is, an electrophotographic photosensitive member having stable characteristics even in repeated use.
In a support and an electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are laminated in this order on the support, the charge transport layer contains at least a charge transport material and a binder resin, The binder resin is a polyarylate resin having a specific structure, and
The glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin are represented by the following formula (A):
−40 (° C.) ≦ (Tg2−Tg1) ≦ 55 (° C.) (A)
An electrophotographic photosensitive member characterized by satisfying the above.
[Selection figure] None

Description

  The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an electrophotographic apparatus, and more particularly, an electrophotographic photoreceptor containing a charge transport material having a specific glass transition temperature and a binder resin in a charge transport layer, and the electrophotographic photoreceptor. The present invention relates to a process cartridge and an electrophotographic apparatus.

  Electrophotographic technology is widely used and applied in the fields of copiers and various printers because of its immediacy and high quality images. Regarding the electrophotographic photosensitive member that is the core image holding member, there are inorganic materials represented by selenium, cadmium sulfide, and zinc oxide. However, in recent years, pollution-free, high productivity, ease of material design and the future Organic materials are being developed extensively from the standpoint of characteristics. These electrophotographic photoreceptors are naturally required to have various characteristics such as electrical, mechanical and optical characteristics according to the applied electrophotographic process. In particular, in electrophotographic photoreceptors that are repeatedly used, electrical and mechanical forces such as charging, exposure, development, transfer, and cleaning are repeatedly applied directly or indirectly, and thus durability against them is required.

  Organic electrophotographic photoreceptors are generally used by mixing a charge transport material with a binder resin, but the inclusion of the charge transport material causes partial strength and flexibility unevenness in the layer. In addition, the mechanical strength is lowered, and in particular, scratches due to peripheral rubbing during repeated use are likely to occur, and the inherent durability of the binder resin may not be utilized.

In order to improve the decrease in mechanical strength of the electrophotographic photosensitive member due to the inclusion of the charge transport material, use a polymer type high molecular weight charge transport material instead of the conventional charge transport material. (For example, refer to Patent Documents 1 to 5). However, the high molecular weight charge transporting substance of the polymer type may have insufficient compatibility depending on the combination with the binder resin. Therefore, separation / precipitation may occur in the coating liquid for the charge transporting layer, Phase separation may occur during the preparation of a photographic photoreceptor, resulting in deterioration of electrophotographic characteristics and abrasion resistance. Thus, further improvement is required from the viewpoint of achieving both the mechanical strength and electrophotographic characteristics of the electrophotographic photosensitive member.
Japanese Patent Laid-Open No. 64-9964 JP-A-2-282263 Japanese Patent Laid-Open No. 3-221522 JP-A-8-208820 International Publication Number WO99 / 32537

  The object of the present invention is to reduce the difference in the glass transition temperature between the charge transport material and the binder resin, and to form a charge transport layer with a specific binder resin. An object of the present invention is to provide an electrophotographic photoreceptor having abrasion resistance and good electrophotographic characteristics, that is, an electrophotographic photoreceptor having stable characteristics even after repeated use.

One embodiment of the present invention is:
[1] In an electrophotographic photosensitive member obtained by laminating a support and a charge generation layer and a charge transport layer in this order on the support,
The charge transport layer contains at least a charge transport material and a binder resin;
The binder resin is represented by the following formula (PA)

(Wherein R _{1 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, or a carbon number of 1 to 3 represents a substituted or unsubstituted alkoxy group, at least one of R _{1 to} R ₄ represents an alkyl group, X represents a single bond, an oxygen atom, a sulfur atom,

R ₉ and R ₁₀ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted aryl group, or R ₉ and R _10. Represents an alkylidene group formed by bonding. )
A polyarylate resin having a repeating structural unit represented by:
The glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin are represented by the following formula (A):
−40 (° C.) ≦ (Tg2−Tg1) ≦ 55 (° C.) (A)
An electrophotographic photoreceptor satisfying the above requirements is provided.

  Preferable embodiments of the electrophotographic photoreceptor according to the present invention include the following [2] to [6] electrophotographic photoreceptors.

[2] The glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin are represented by the following formula (B):
−20 (° C.) ≦ (Tg2−Tg1) ≦ 40 (° C.) (B)
The electrophotographic photosensitive member according to the above [1], wherein

  [3] The electrophotographic photosensitive member according to the above [1] or [2], wherein the charge transport material has a glass transition temperature (Tg1) of 140 ° C. or higher.

  [4] The electrophotographic photosensitive member according to any one of [1] to [3], wherein the charge transport material has a repeating structural unit represented by the following formula (1):

(In formula (1), Ar ¹¹ represents a substituted or unsubstituted monovalent aromatic hydrocarbon ring group or a substituted or unsubstituted monovalent aromatic heterocyclic group. Ar ¹² represents the following formula: (2) represents a divalent group having a structure represented by a formula selected from the group consisting of the following formula (2) ′ and the following formula (2) ″:

(In Formula (2), Ar ²¹ and Ar ²² each independently represent a substituted or unsubstituted trivalent aromatic ring group or a substituted or unsubstituted trivalent heterocyclic group. A ²¹ , A ²² is independently a single bond, hydrogen, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkyleneoxy group, a group 14 element having an electron withdrawing group, an electron withdrawing group Represents a group 15 element or a group 16 element having the following: c represents 0 or 1;
In formula (2) ′, Ar ²¹ ′ and Ar ²² ′ each independently represent a substituted or unsubstituted divalent aromatic ring group or a substituted or unsubstituted divalent heterocyclic group. A ²¹ ′ is a hydrogen atom, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkyleneoxy group, a group 14 element having an electron withdrawing group, or a group 15 element having an electron withdrawing group Or a group 16 element. c ′ represents 1;
In formula (2) ″, A21 ″ represents a substituted or unsubstituted divalent aromatic ring group, or a substituted or unsubstituted divalent heterocyclic group. c ″ represents an integer of 1 or more. However, when c ″ is 2 or more, two or more Ar 21 ″ may be the same or different)).

  [5] The electrophotographic photoreceptor according to any one of [1] to [4], wherein the charge transport material has a molecular weight or a weight average molecular weight (Mw) of 1500 or more and 5500 or less.

[6] The electrophotographic photosensitive member according to any one of [1] to [5], wherein the polyarylate resin has a methyl group in each of R ₁ and R ₂ .

Another aspect of the present invention is:
[7] An electrophotographic photosensitive member according to any one of the above [1] to [6] and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means are integrally supported, and an electron Provided is a process cartridge which is detachable from a photographic apparatus main body.

Yet another aspect of the present invention provides:
[8] An electrophotographic apparatus comprising the electrophotographic photosensitive member according to any one of [1] to [6], a charging unit, an exposure unit, a developing unit, and a transfer unit.

  According to the present invention, an electrophotographic photosensitive member having a charge transport layer containing a specific binder resin, which reduces the difference in glass transition temperature between the charge transport material and the binder resin, has abrasion resistance in repeated use. It is possible to provide a uniform image without improvement and image deterioration due to potential fluctuation.

In the electrophotographic photoreceptor of the present invention, the glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin are represented by the following formula (A).
−40 (° C.) ≦ (Tg2−Tg1) ≦ 55 (° C.) (A)
By using a polyarylate resin that satisfies the above requirements and has a specific repeating structural unit, the compatibility between the charge transport material and the binder resin is improved, phase separation does not occur, and wear resistance and scratches are generated. The effect of suppressing is remarkably exhibited. Preferably, the following formula (B)
−20 (° C.) ≦ (Tg2−Tg1) ≦ 40 (° C.) (B)
More preferably, the following formula (C)
−20 (° C.) ≦ (Tg2−Tg1) ≦ 20 (° C.) (C)
Is to satisfy.

  The charge transport material of the electrophotographic photoreceptor of the present invention may have any structure as long as it satisfies the above formula (A), but the glass transition temperature (Tg1) of the charge transport material is It is 140 degreeC or more, More preferably, it is 140 degreeC or more and 230 degrees C or less.

  In order to increase the glass transition temperature of the charge transport material, it is preferable to incorporate a more rigid structure in the charge transport material. Therefore, the charge transport material preferably has a repeating structural unit represented by the following formula (1).

(In formula (1), Ar ¹¹ represents a substituted or unsubstituted monovalent aromatic hydrocarbon ring group or a substituted or unsubstituted monovalent aromatic heterocyclic group. Ar ¹² represents the following formula: (2) represents a divalent group having a structure represented by a formula selected from the group consisting of the following formula (2) ′ and the following formula (2) ″:

(In Formula (2), Ar ²¹ and Ar ²² each independently represent a substituted or unsubstituted trivalent aromatic ring group or a substituted or unsubstituted trivalent heterocyclic group. A ²¹ , A ²² is independently a single bond, hydrogen, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkyleneoxy group, a group 14 element having an electron withdrawing group, an electron withdrawing group Represents a group 15 element or a group 16 element having the following: c represents 0 or 1;
In formula (2) ′, Ar ²¹ ′ and Ar ²² ′ each independently represent a substituted or unsubstituted divalent aromatic ring group or a substituted or unsubstituted divalent heterocyclic group. A ²¹ ′ is a hydrogen atom, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkyleneoxy group, a group 14 element having an electron withdrawing group, or a group 15 element having an electron withdrawing group Or a group 16 element. c ′ represents 1;
In formula (2) ″, A21 ″ represents a substituted or unsubstituted divalent aromatic ring group, or a substituted or unsubstituted divalent heterocyclic group. c ″ represents an integer of 1 or more. However, when c ″ is 2 or more, two or more Ar 21 ″ may be the same or different)).

  More preferably, it is a charge transport material having a structure represented by any of the following formulas (4) to (8).

In the above formulas (4) to (8), Ar _{101 to} Ar ₅₁₂ are each independently a substituted or unsubstituted monovalent aromatic hydrocarbon ring group, or a substituted or unsubstituted monovalent aromatic. Represents a heterocyclic group, and Z _{11 to} Z ₅₉ represent a substituted or unsubstituted divalent aromatic hydrocarbon ring group or a substituted or unsubstituted divalent aromatic heterocyclic group.

The substituted or unsubstituted monovalent aromatic hydrocarbon ring group represented by Ar ₁₀₁ to Ar ₅₁₂ constituting the compounds represented by the above formulas (4) to (8) includes a phenyl group, a naphthyl group, an anthracenyl group, and a pyrenyl group. Examples of the substituted or unsubstituted monovalent aromatic heterocyclic group include pyridyl group, indole group, quinolinyl group, benzofuranyl group, dibenzofuranyl group, benzothiophenyl group, and dibenzothiophenyl group. Can be mentioned. Of these, a phenyl group, a naphthyl group, a pyridyl group, a benzofuranyl group, and a benzothiophenyl group are preferable. These substituents include a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aromatic hydrocarbon ring group having any of 3 to 12 carbon atoms, and 1 to 8 carbon atoms. Any of alkoxy groups, halogen atoms, fluorinated alkyl groups, cyano groups, nitro groups, etc. are mentioned. Among them, hydrogen atom, methyl group, ethyl group, methoxy group, fluorine atom, chlorine atom, bromine atom, A fluoromethyl group is preferred.

Examples of the substituted or unsubstituted divalent aromatic hydrocarbon ring group represented by Z _{11 to} Z ₅₉ constituting the compounds represented by the above formulas (4) to (8) include a phenylene group, a biphenylene group, and a terphenylene group. Fluorenylene group, naphthylene group, anthracenylene group, pyrenylene group, etc., and the substituted or unsubstituted divalent aromatic heterocyclic group includes pyridinylene group, indoleylene group, quinolinylene group, benzofuranylene group, dibenzofuranylene group Benzothiophenylene group, dibenzothiophenylene group and the like. In addition, the above divalent aromatic hydrocarbon ring or divalent aromatic heterocyclic group may be a single bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, an alkylidene group, a substituted or A substituted or unsubstituted divalent aromatic hydrocarbon ring group or a substituent formed by linking with an unsubstituted silicon group having 1 to 4 silicon atoms, an oxygen atom, or a sulfur atom Or it is mentioned as an unsubstituted divalent aromatic heterocyclic group. Among substituted or unsubstituted divalent aromatic hydrocarbon ring groups, or substituted or unsubstituted divalent aromatic heterocyclic groups, biphenylene group, fluorenylene group, pyridinylene group, dibenzofuranylene group, benzothiophenylene Group is preferable, and among them, a biphenylene group, a dibenzofuranylene group, and a benzothiophenylene group are more preferable. More preferably, at least one of Z _{11 to} Z ₅₉ is a substituted or unsubstituted dibenzofuranylene group or a substituted group. or be unsubstituted benzothiophenyl phenylene group, other Z ₁₁ to Z ₅₉ are substituted or unsubstituted biphenylene group.

  Examples of the substituent of these divalent aromatic hydrocarbon ring group or divalent aromatic heterocyclic group include a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and 3 to 12 carbon atoms. An aromatic hydrocarbon ring group which is any of the above, an alkoxy group having any one of 1 to 8 carbon atoms, a halogen atom, a fluorinated alkyl group, a cyano group, a nitro group, etc., among them, a hydrogen atom, A methyl group, ethyl group, propyl group, methoxy group, ethoxy group, fluorine atom, chlorine atom, bromine atom and trifluoromethyl group are preferred.

  Examples of the specific structure of the charge transport material of the present invention are shown below, but are not particularly limited.

(The parentheses in the above formulas (CT-66) to (CT-69) represent repeating structural units, and n represents the number of repetitions of the repeating structural units in the parentheses.)

  When the molecular weight is increased by the repeating structural unit represented by the above formula (1), the compatibility with the binder resin becomes insufficient, causing separation / precipitation in the coating solution for the charge transport layer, or at the time of preparing an electrophotographic photoreceptor. Phase separation may occur, resulting in deterioration of electrophotographic photoreceptor characteristics. In particular, when the electrophotographic photosensitive member is repeatedly used, the chargeability is remarkably lowered, and the constitution becomes inappropriate for the electrophotographic photosensitive member used for a long time. The higher the number of repetitions, the higher the glass transition temperature of the charge transport material, but the rigid structure contributes to a decrease in compatibility with the resin, so the molecular weight of the charge transport material is the weight average molecular weight of gel permeation chromatography ( If the Mw) exceeds 5500, the characteristics may be deteriorated. If the weight average molecular weight of the charge transport material is less than 1500, the glass transition temperature tends to decrease, and the inherent mechanical strength of the binder resin. May not be able to be demonstrated. Therefore, the molecular weight or the weight average molecular weight (Mw) of the charge transport material is preferably 1500 or more and 5500 or less, more preferably 1500 or more and 4000 or less, and further preferably 1500 or more and 3500 or less.

  Next, the binder resin used in the charge transport layer in the present invention is a polyarylate resin having a repeating structural unit represented by the following formula (PA).

(Wherein R _{1 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, or a carbon number of 1 to 3 represents a substituted or unsubstituted alkoxy group, at least one of R _{1 to} R ₄ represents an alkyl group, X represents a single bond, an oxygen atom, a sulfur atom,

R ₉ and R ₁₀ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted aryl group, or R ₉ and R _10. Represents an alkylidene group formed by bonding. )

From the viewpoint of compatibility with the charge transport material, the polyarylate resin having a repeating structural unit represented by the above formula (PA) needs to have an alkyl group in at least one of R _{1 to} R ₄ , and R ₁ and R ₂ each preferably have an alkyl group, and more preferably R ₁ and R ₂ each have a methyl group.

  Specific examples of the structure of the polyarylate resin having a repeating unit structure represented by the above formula (PA) are shown below, but the structure is not particularly limited.

  As for the structure of the phthalic acid moiety used in the polyarylate resin, isophthalic acid or terephthalic acid is used. The ratio of terephthalic acid to isophthalic acid in the resin (isophthalic acid / terephthalic acid) can be arbitrarily from 0/100 to 100/0 in terms of mass ratio, but from the viewpoint of solubility of the polyarylate resin in the solvent, isophthalic acid / Terephthalic acid is preferably 20/80 to 80/20. Furthermore, from the viewpoint of the strength of the polyarylate resin, isophthalic acid / terephthalic acid = 30/70 to 70/30 is preferable.

  The divalent organic residue part constituting the polycarbonate resin or polyarylate resin is substituted or unsubstituted divalent biphenyl residue, substituted or unsubstituted divalent bisphenyl residue, substituted or unsubstituted divalent Any structure can be used as long as it is a divalent organic residue such as a biphenyl ether residue or a substituted or unsubstituted divalent biphenylthioether residue, but a substituted or unsubstituted divalent It is preferably a biphenyl residue, a substituted or unsubstituted divalent bisphenyl residue, or a substituted or unsubstituted divalent biphenyl ether residue.

  The weight average molecular weight (Mw) of the binder resin is preferably Mw = 50000 to 200000, and Mw = 80000 to 150,000 is particularly preferable from the viewpoint of strength, productivity, and the like.

  In order to add other characteristics such as strength and solubility, a copolymer with a bisphenol having another structure may be used. The ratio of copolymerization can exert the effect of each characteristic in 95/5 to 5/95. In addition, it can be blended with polyarylate resin or polycarbonate resin of other structure to improve productivity. However, from the viewpoint of strength and compatibility with the charge transport material, the polyarylate resin of the present invention is used for charge transport. It is preferable that 50 mass% or more is contained with respect to the total amount of the binder constituting the layer.

  Further, the glass transition temperature (Tg2) of the binder resin used in the electrophotographic photosensitive member of the present invention is preferably 170 ° C. or higher, more preferably 180 ° C. or higher and 230 ° C. or lower.

  By using a binder resin and a charge transport material having a specific repeating structural unit, the glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin satisfy the above formula (A), The reason why it can provide excellent image quality over a long period of time by suppressing the decrease in charging ability when it is excellent in electrophotographic characteristics, especially in repetitive use is not clarified in detail, but is considered as follows.

  In order to make use of the mechanical strength of the binder resin, it is necessary to suppress unevenness in partial strength and flexibility due to the inclusion of the charge transport material. One possible cause of this unevenness is a large difference in glass transition temperature between the charge transport material and the binder resin. That is, it is speculated that the substances having different glass transition temperatures are different in the ease of relaxation of the substance during the drying process of the electrophotographic photosensitive member, and the above-described problem occurs. On the other hand, as in the present invention, the high mechanical strength of the binder resin is maintained by reducing the difference in glass transition temperature between the charge transport material and the binder resin. As for the electrophotographic characteristics, the charge transport material having a high glass transition temperature as described above tends to cause a decrease in compatibility with the binder resin, and the electrophotographic characteristics deteriorate due to the decrease in compatibility. In particular, there was a decrease in charging ability. On the other hand, it is considered that compatibility was improved by using a polyarylate resin having a specific repeating structure as a binder resin, and good electrophotographic characteristics were exhibited.

  Among them, the charge transporting material having the repeating structural unit represented by the above formula (1) not only has a glass transition temperature close to that of the binder resin but also has a high charge transporting ability, so that it is very useful as a charge transporting material. Useful.

  Hereinafter, the structure of the electrophotographic photosensitive member used in the present invention will be described.

  The support used in the electrophotographic photosensitive member of the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc, stainless steel in the form of a drum or a sheet. Examples include a molded product, a laminate of a metal foil such as aluminum or copper on a plastic film, and a product obtained by evaporating aluminum, indium oxide, tin oxide, or the like on a plastic film.

  When the image input such as LBP is laser light, a conductive layer may be provided for the purpose of preventing interference fringes due to scattering or covering a scratch on the support.

  This can be formed by dispersing conductive particles such as carbon black and metal particles in a binder resin.

  5-40 micrometers is preferable and, as for the film thickness of a conductive layer, 10-30 micrometers is more preferable.

  Further, an intermediate layer having an adhesive function may be provided on the support or the conductive layer.

  Examples of the material for the intermediate layer include polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane. These are dissolved in an appropriate solvent and applied.

  The thickness of the intermediate layer is preferably 0.05 to 5 μm, more preferably 0.3 to 1 μm.

  In the case of the function separation type (laminated type) photosensitive layer, a charge generation layer is formed on the support, the conductive layer or the intermediate layer.

  The charge generation layer is formed by a method such as homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor, roll mill and liquid collision type high-speed disperser together with 0.3 to 4 times the amount of binder resin and solvent. It is formed by dispersing well and applying and drying the dispersion.

  The thickness of the charge generation layer is preferably 5 μm or less, more preferably 0.1 to 2 μm.

  As the charge generation material, those generally known can be used, for example, selenium-tellurium, pyrylium, metal phthalocyanine, metal-free phthalocyanine, anthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo. And pigments such as quinacrine.

  These pigments were well dispersed using a homogenizer, ultrasonic dispersion, ball mill, vibration mill, sand mill attritor, roll mill, liquid collision type high-speed disperser, etc. together with binder resin and solvent having a weight of 0.3 to 4 times. A dispersion is obtained. In the case of a functional separation type (laminated type) photosensitive layer, a charge generation layer is obtained by applying this solution and drying.

  In the case of a function separation type (laminated type) photosensitive layer, a charge transport layer is formed on the charge generation layer.

  The charge transport layer is prepared by dissolving the charge transport material and an insulating binder resin in a solvent to form a coating solution, coating the solution on the charge generation layer, and drying.

  The ratio of the charge transport material to the binder resin (charge transport material / binder resin) is preferably 1/10 to 12/10 in terms of mass ratio, from the viewpoint of the charge transport characteristics of the electrophotographic photoreceptor or the strength of the charge transport layer. 2/10 to 8/10 is more preferable.

  When the charge transport layer is a surface layer of an electrophotographic photosensitive member, a lubricant or fine particles may be used as necessary. Examples of the lubricant or fine particles include polytetrafluoroethylene fine particles, silica fine particles, and alumina fine particles.

  The thickness of the charge transport layer is preferably 5 to 40 μm, and preferably 15 to 30 μm.

  In the step of forming each layer of the electrophotographic photoreceptor, examples of the solvent to be used include chlorobenzene, tetrahydrofuran, 1,4-dioxane, toluene, xylene, and the like. A single solvent or a plurality of solvents may be used.

  Further, as the coating method, a conventionally known method such as a dip coating method, a spray coating method, or a bar coating method can be used.

  FIG. 1 shows a schematic configuration of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 2 in the direction of an arrow at a predetermined peripheral speed. In the rotating process, the electrophotographic photosensitive member 1 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by the primary charging unit 3, and then from an exposure unit (not shown) such as slit exposure or laser beam scanning exposure. The exposure light 4 is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1.

  The formed electrostatic latent image is then developed with toner by the developing means 5, and the developed toner developed image is transferred between the electrophotographic photosensitive member 1 and the transfer means 6 from a paper supply unit (not shown). The image is sequentially transferred by the transfer means 6 to the transfer material 7 fed in synchronization with the rotation of 1.

  The transfer material 7 that has received the image transfer is separated from the surface of the electrophotographic photosensitive member, introduced into the image fixing means 8, and subjected to image fixing to be printed out as an image formed product (copy or print).

  After the image transfer, the surface of the electrophotographic photosensitive member 1 is cleaned by the removal of the toner remaining after the transfer by the cleaning unit 9, and is further subjected to charge removal processing by the pre-exposure light 10 from the pre-exposure unit (not shown). Used repeatedly for image formation. When the primary charging unit 3 is a contact charging unit using a charging roller as shown in FIG. 1, pre-exposure is not necessarily required.

  In the present invention, a plurality of components such as the above-described electrophotographic photosensitive member 1, primary charging unit 3, developing unit 5, and cleaning unit 9 are integrally coupled as a process cartridge. May be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 3, the developing unit 5 and the cleaning unit 9 is integrally supported together with the electrophotographic photosensitive member 1 to form a cartridge, and can be attached to and detached from the apparatus main body using guide means such as the rail 12 of the apparatus main body. Process cartridge 11.

  Further, when the electrophotographic apparatus is a copying machine or a printer, the exposure light 4 is a reflected light or transmitted light from the original, or the original is read by a sensor and converted into a signal, and a laser beam performed in accordance with this signal. The light is emitted by scanning, driving the LED array, driving the liquid crystal shutter array, and the like.

  The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also widely in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”.

(Example 1)
A coating composed of the following materials was applied on an aluminum cylinder having a diameter of 30 mm and a length of 357 mm by a dip coating method, and was thermally cured at 150 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm. .

Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol / methoxypropanol = 2/8 20 parts

  Next, a solution obtained by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol is applied onto this conductive layer by a dip coating method and dried. Thus, an intermediate layer having a film thickness of 0.6 μm was formed.

  Next, 4 parts of hydroxygallium phthalocyanine having strong peaks at 7.4 ° and 28.2 ° of diffraction angle 2θ ± 0.2 ° in the X-ray diffraction spectrum of CuKα, polyvinyl butyral (Esrec BX-1, Sekisui Chemical ( 2 parts) and 60 parts of cyclohexanone were dispersed in a sand mill apparatus using glass beads having a diameter of 1 mm for 4 hours, and then 100 parts of ethyl acetate was added to prepare a dispersion for charge generation layer. This was applied onto the intermediate layer by a dipping method to form a charge generation layer having a thickness of 0.2 μm.

  Next, 6 parts of a charge transport material having a structure represented by (CT-10) and 10 parts of a polyarylate resin having a repeating structural unit represented by (PA-2) and having a weight average molecular weight (Mw) of 130000 ( The mass ratio of terephthalic acid and isophthalic acid in the resin: terephthalic acid / isophthalic acid = 50/50) was dissolved in 85 parts of monochlorobenzene to prepare a coating solution for a charge transport layer. This was applied on the charge generation layer by a dipping method and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 25 μm.

  Thus, the electrophotographic photosensitive member of each example was produced.

  Next, evaluation of the electrophotographic photosensitive member of the present invention will be described.

The evaluation of the dark part potential (Vd) and the bright part potential (Vl) of the electrophotographic photosensitive member using the production method of the present invention and the fluctuation of the dark part potential (ΔVd) during repeated use of the electrophotographic photosensitive member was performed by Canon Inc. Evaluation made by modifying the photocopier GP215 (contact charging method) so that the image exposure amount was 0.5 μJ / cm ² on the surface of the electrophotographic photosensitive member, and the initial dark portion potential was adjusted to −750V. This was done using a machine. The evaluation of fluctuations in potential characteristics due to repeated use of the electrophotographic photosensitive member was performed by copying 20000 sheets in an intermittent mode in which A4 size plain paper is stopped once for each copy, and measuring the surface potential before and after that. . Note that the fluctuation (ΔVd) of the dark portion potential during repeated use indicates a value (ΔVd = Vd−Vd ′) obtained by subtracting the initial dark portion potential (Vd) from the dark portion potential (Vd ′) after repeated use.

  The surface potential of the electrophotographic photosensitive member was measured at the developing device position by exchanging the jig and the developing device fixed so that the potential measuring probe was positioned at a position 180 mm from the upper end of the electrophotographic photosensitive member.

  Evaluation of durability characteristics by repeated use of the electrophotographic photosensitive member is performed by copying 20000 sheets in an intermittent mode in which A4 size plain paper is stopped once for each copy, and then measuring the film thickness of the electrophotographic photosensitive member. The amount of wear was measured. The film thickness was measured with a film thickness meter (Fischer Scope MMS eddy current probe EAW3.3, manufactured by Fisher Instruments Co., Ltd.). Further, scratches on the photoreceptor after repeated use were evaluated. The evaluation of the flaw is an evaluation (evaluation length: 8 mm) according to the ten-point average roughness (Rzjis) evaluation in JIS B 0601: 2001 with a surface roughness measuring device (Surfcoder SE-3400, manufactured by Konishi Laboratory Co., Ltd.). ) And a position 180 mm from the upper end of the electrophotographic photosensitive member was measured.

  The glass transition temperature (Tg1) of the charge transport material was measured by thermomechanical analysis under the following conditions. First, the powder of the charge transport material was heated and melted, and then rapidly cooled to prepare a glass sample. Next, this sample was heated at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC-7000, manufactured by Vacuum Riko Co., Ltd.), and the glass transition temperature was determined from the obtained differential heat curve. The glass transition temperature (Tg2) of the binder resin was also determined by the same measurement method.

  In addition, the weight average molecular weight of the charge transport material is measured by ordinary gel permeation chromatography (GPC) (column used: Showa Denko KF-802, developing solvent: methanol / tetrahydrofuran = 7/3, detector: The RI detector and the molecular weight of the sample were determined by a polystyrene conversion method). When the charge transporting material is a compound having only a specific molecular structure, it was determined by the same measurement method, and the obtained value was used as the molecular weight of the charge transporting material. Moreover, the weight average molecular weight of binder resin was calculated | required with the same measuring method.

  The results are shown in Table 1.

(Example 2)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that a charge transport material having a structure represented by (CT-17) was used as the charge transport material, and the same evaluation was performed. The results are shown in Table 1.

(Example 3)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that a charge transport material having a structure represented by (CT-65) was used as the charge transport material, and the same evaluation was performed. The results are shown in Table 1.

Example 4
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a charge transport material having a repeating structural unit represented by (CT-66) having a weight average molecular weight (Mw) of 2150 was used as the charge transport material. Similar evaluations were made. The results are shown in Table 1.

(Example 5)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a charge transport material having a repeating structural unit represented by (CT-68) having a weight average molecular weight (Mw) of 3520 was used as the charge transport material. Similar evaluations were made. The results are shown in Table 1.

(Examples 6 to 8)
As a binder resin for the charge transport layer, a polyarylate resin having a repeating structural unit represented by (PA-10) having a weight average molecular weight (Mw) of 80,000 (mass ratio of terephthalic acid and isophthalic acid in the resin: terephthalic acid / Except that isophthalic acid = 50/50) was used, an electrophotographic photoreceptor was prepared in the same manner as in Examples 1, 3, and 4, and the same evaluation was performed. The results are shown in Table 1.

Example 9
As a binder resin for the charge transport layer, a polyarylate resin having a repeating structural unit represented by (PA-15) having a weight average molecular weight (Mw) of 150,000 (mass ratio of terephthalic acid and isophthalic acid in the resin: terephthalic acid / An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that isophthalic acid = 50/50) was used, and the same evaluation was performed. The results are shown in Table 1.

(Examples 10 to 12)
As a binder resin for the charge transport layer, a copolymerized polyarylate resin having a repeating structural unit represented by (PA-2) and a repeating structural unit represented by (PA-9) having a weight average molecular weight (Mw) of 130,000 ( Example 6 except that copolymerization ratio: (PA-2) / (PA-9) = 7/3, mass ratio of terephthalic acid to isophthalic acid in resin: terephthalic acid / isophthalic acid = 50/50) The electrophotographic photosensitive member was produced in the same manner as in -8, and the same evaluation was performed. The results are shown in Table 1.

(Examples 13 to 15)
As a binder resin for the charge transport layer, a copolymer polyarylate resin (copolymerization ratio: (Mw = 130,000) having a repeating structural unit represented by (PA-2) and a repeating structural unit represented by (PA-9). PA-2) / (PA-9) = 7/3, the mass ratio of terephthalic acid to isophthalic acid in the resin: terephthalic acid / isophthalic acid = 50/50) is 45 parts, and the following formula (9) An electrophotographic photosensitive member was prepared in the same manner as in Examples 6 to 8 except that 40 parts of polycarbonate resin having a repeating structural unit (Iupilon Z400, manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used. It was. The results are shown in Table 1.

(Comparative Examples 1-3)
An electrophotographic photoreceptor in the same manner as in Examples 6 to 8, except that a polyarylate resin (U100, manufactured by Unitika Ltd.) having a repeating structural unit represented by the following formula (10) was used as the binder resin for the charge transport layer. The same evaluation was performed. The results are shown in Table 1.

(Comparative Examples 4-7)
An electrophotographic photosensitive member was prepared in the same manner as in Examples 1, 6, 10, and 13 except that a charge transport material having a structure represented by the following formula (11) was used as the charge transport material. It was. The results are shown in Table 1.

(Comparative Example 8)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a charge transport material having a repeating structural unit represented by (CT-66) having a weight average molecular weight (Mw) of 5960 was used as the charge transport material. Similar evaluations were made. The results are shown in Table 1.

1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus having the electrophotographic photosensitive member of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Primary charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Image fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Rail

Claims (8)

In an electrophotographic photosensitive member formed by laminating a support and a charge generation layer and a charge transport layer in this order on the support,
The charge transport layer contains at least a charge transport material and a binder resin;
The binder resin is represented by the following formula (PA)

(Wherein R _{1 to} R ₈ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, or a carbon number of 1 to 3 represents a substituted or unsubstituted alkoxy group, at least one of R _{1 to} R ₄ represents an alkyl group, X represents a single bond, an oxygen atom, a sulfur atom,

R ₉ and R ₁₀ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, a substituted or unsubstituted aryl group, or R ₉ and R _10. Represents an alkylidene group formed by bonding. )
A polyarylate resin having a repeating structural unit represented by:
The glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin are represented by the following formula (A):
−40 (° C.) ≦ (Tg2−Tg1) ≦ 55 (° C.) (A)
An electrophotographic photosensitive member characterized by satisfying the above. The glass transition temperature (Tg1) of the charge transport material and the glass transition temperature (Tg2) of the binder resin are represented by the following formula (B).
−20 (° C.) ≦ (Tg2−Tg1) ≦ 40 (° C.) (B)
The electrophotographic photosensitive member according to claim 1, wherein:   The electrophotographic photosensitive member according to claim 1 or 2, wherein the charge transport material has a glass transition temperature (Tg1) of 140 ° C or higher. The electrophotographic photoreceptor according to claim 1, wherein the charge transport material has a repeating structural unit represented by the following formula (1):

(In formula (1), Ar ¹¹ represents a substituted or unsubstituted monovalent aromatic hydrocarbon ring group or a substituted or unsubstituted monovalent aromatic heterocyclic group. Ar ¹² represents the following formula: (2) represents a divalent group having a structure represented by a formula selected from the group consisting of the following formula (2) ′ and the following formula (2) ″:

(In Formula (2), Ar ²¹ and Ar ²² each independently represent a substituted or unsubstituted trivalent aromatic ring group or a substituted or unsubstituted trivalent heterocyclic group. A ²¹ , A ²² is independently a single bond, hydrogen, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkyleneoxy group, a group 14 element having an electron withdrawing group, an electron withdrawing group Represents a group 15 element or a group 16 element having the following: c represents 0 or 1;
In formula (2) ′, Ar ²¹ ′ and Ar ²² ′ each independently represent a substituted or unsubstituted divalent aromatic ring group or a substituted or unsubstituted divalent heterocyclic group. A ²¹ ′ is a hydrogen atom, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkyleneoxy group, a group 14 element having an electron withdrawing group, or a group 15 element having an electron withdrawing group Or a group 16 element. c ′ represents 1;
In formula (2) ″, A21 ″ represents a substituted or unsubstituted divalent aromatic ring group, or a substituted or unsubstituted divalent heterocyclic group. c ″ represents an integer of 1 or more. However, when c ″ is 2 or more, two or more Ar 21 ″ may be the same or different)).   The electrophotographic photosensitive member according to claim 1, wherein the charge transport material has a molecular weight or a weight average molecular weight (Mw) of 1500 or more and 5500 or less. The electrophotographic photosensitive member according to claim ₁ , wherein the polyarylate resin has a methyl group in each of R ₁ and R ₂ .   7. The electrophotographic photosensitive member according to claim 1 and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means are integrally supported and detachably attached to the electrophotographic apparatus main body. Process cartridge characterized by being.   An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, and a transfer unit.

Images