JP2770462B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member having an improved photosensitive layer.

[Prior Art] Conventionally, an electrophotographic photoreceptor using a stacked type photosensitive layer having a configuration in which a charge generating material for generating charges and a charge transporting material for transferring charges are separated into respective layers, and both in the same layer And a photoreceptor using a single-layer photosensitive layer.
These photosensitive layers are formed by dispersing or dissolving the substance in a binder resin.

When such an electrophotographic photosensitive member is applied to a usual electrophotographic process such as the Carlson method, various problems have occurred. For example, since the compatibility between the charge transfer material and the binder resin is poor, there has been a defect that the charge transfer material is crystallized or deteriorated with the lapse of time. For example, in the case of a photoconductor provided with a charge transfer layer composed of a charge transfer material and a binder resin on the surface layer, abrasion due to adhesion of toner to the surface of the photosensitive layer and contact between the developer and transfer paper and the surface of the photosensitive layer are reduced. There is a drawback that scratches occur.

Polycarbonate, polyester, polymethyl methacrylate, and the like have been proposed as binder resins for the photosensitive layer that solve these problems.

[Problems to be Solved by the Invention] However, even when these binder resins are used, the above-mentioned disadvantages cannot be sufficiently solved.

Further, it has been proposed to provide a protective layer on the photosensitive layer. However, as long as the above-mentioned resin is used as a binder resin of the protective layer, the above-mentioned disadvantages cannot be sufficiently solved.

The present invention has been made in view of the problems of the prior art as described above, and its object is to improve chemical durability such as improvement in compatibility with a charge transfer agent and electrical durability such as electrophotographic sensitivity. It is an object of the present invention to provide an electrophotographic photoreceptor having cleaning properties such as toner properties, toner cleaning properties and toner filming properties, and mechanical durability such as abrasion resistance and scratch resistance.

[Means for Solving the Problems] To achieve the above object, the present invention has the following configuration.

(1) In an electrophotographic photosensitive member having at least a conductive support and a photosensitive layer, the photosensitive layer mainly includes a repeating unit represented by the following general formula (I) and a repeating unit represented by the following general formula (II). An electrophotographic photosensitive member comprising a binder resin made of a fluorine-containing polyester as a component.

(In the general formulas (I) and (II), X is -O-,-
R is at least one selected from the group consisting of CO-O-, -CO-NH-, and -CO-, and r represents 0 or 1. R ¹ has 1 carbon atom substituted by at least one fluorine atom
And represents an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 1 to 20 carbon atoms substituted by at least one fluorine atom. R ² represents a divalent aromatic group. R ³ represents a divalent organic residue. The molar ratio of m / n is from 1/99 to 100/0. In the present invention, R ¹ is an alkyl group having 1 to 20 carbon atoms substituted by at least one fluorine atom or 1 carbon atom substituted by at least one fluorine atom.
Represents up to 20 alkenyl groups. The carbon number of R ¹ is preferably 2 or more, more preferably 3 to 15, from the viewpoint of the reactive toner filming property and toner cleaning property of dicarboxylic acid, which is a starting material for polyester. The number of fluorine atoms substituted in R ¹ is preferably 2 or more from the viewpoint of toner filming properties and toner cleaning properties. Further, R ¹ is preferably an alkyl group having 3 or more carbon atoms or an alkenyl group having 3 or more carbon atoms. From the viewpoint of preference, the number of fluorine atoms is particularly preferably 5 or more. The terminal of the alkyl group or alkenyl group is preferably fluorinated from the viewpoint of exhibiting high toner filming property and toner cleaning property.

R ¹ may be linear or branched. Specific examples in which R ¹ is a straight chain include a methyl group, an ethyl group, an n-propyl group, an n-butyl group substituted with at least one fluorine atom,
n-pentyl group, n-hexyl group, n-heptyl group, n
-Octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group and the like.

Specific examples in which R ¹ is branched include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1-methylbutyl group, a 2-methylbutyl group substituted with at least one fluorine atom. 3-methylbutyl group, 1,
1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,
2-dimethylpropyl group, 1-ethyl-2-methyl-1
-Propenyl group, 2-isopropyl-1,3-dimethyl-
Examples thereof include a 1-butenyl group.

The polyester having a repeating unit represented by the general formula (I) can be produced from a dicarboxylic acid dihalide represented by the following general formula (III) and a diol represented by the following general formula (V).

In addition, polyesters containing the repeating units represented by the above general formulas (I) and (II) as main components are represented by the following general formula (II)
It can be produced from dicarboxylic acid dihalides represented by I) and (IV) and a diol represented by the following general formula (V).

(Wherein X, r, R ¹ is the same as the general formula (I), Z is a halogen ^{group.) Z-CO-R 3} -CO-Z (IV) ( wherein R ³ has the general formula As in (II), Z is a halogen group.

^{HO-R 2 -OH (V)} ( wherein R ² is the same as in the general formula (I).) As a method for producing dicarboxylic acid dihalide represented by the general formula (III), a dicarboxylate benzene derivatives And a compound containing an alkyl group or an alkenyl group substituted by at least one fluorine atom to synthesize a compound represented by the following general formula (VI).
Alternatively, a method comprising reacting a xylene derivative with a compound containing an alkyl group or an alkenyl group substituted by at least one fluorine atom, and then converting two methyl groups bonded to the benzene ring to a carboisyl group with a conventionally known oxidizing agent. To synthesize a compound represented by the following general formula (VI). Next, a method of halogenating the obtained compound (VI) with a conventionally known halogenating agent for various carboxylic acids may be mentioned.

(Wherein X, r, and R ¹ are the same as those in the general formula (I).) Examples of the dicarboxylic acid represented by the general formula (VI) include dicarboxybenzene fluoroalkyl ether;
Examples thereof include fluoroalkyl dicarboxybenzoate, N-fluoroalkyldicarboxybenzamide, dicarboxybenzenefluoroalkylketone, and dicarboxyfluoroalkylbenzene.

Examples of the dicarboxylic acid dihalide represented by the general formula (IV) include the following dicarboxylic acid dichlorides:
Examples thereof include difluoride and dibromide. That is, terephthalic acid, tetrafluoroterephthalic acid, isophthalic acid, tetrafluoroisophthalic acid,
Examples include naphthalenedicarboxylic acid, 4,4'-diphenylether dicarboxylic acid, dichlorides such as oxalic acid, succinic acid, adipic acid and sebacic acid, difluoride and dibromide.

When these dicarboxylic acid halides are used as a mixture, the dicarboxylic acid halide represented by the above general formula (III) is contained in an amount of 5 mol% or more, so that the toner filming property and the toner cleaning property, which are one feature of the present invention. Can be sufficiently improved.

In the above general formula (V), R ² which is a divalent aromatic group
In particular, it is desirable to use 1 to 4 nuclei. Specific examples include catechols, resorcines, hydroquinones, dihydroxybiphenyls, bis (hydroxyphenyl) ethanes, and the like.

In the present invention, these aromatic diols may be partially mixed with an aliphatic diol for use. Usable diols include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol and the like.

When these aliphatic diols are used as a mixture, the glass transition temperature can be sufficiently increased and the mechanical durability can be improved by containing the aromatic diol at 70 mol% or more.

The preferred molecular weight is in the range of 0.1 to 2.0 dl / g in terms of intrinsic viscosity from the viewpoint of mechanical durability and the like.
It is particularly preferred that it is in the range of ~ 1.5 dl / g.

In the present invention, the dicarboxylic acid dihalide of the above (III) is used in an amount of 100 to 1 mol%, and the remaining 0 to 99 mol% of the dicarboxylic acid dihalide of the above general formula (IV) is used. By reacting with a diol represented by the general formula (I) or (II),
A polyester is produced in which m / n is in a molar ratio of 100/0 to 1/99.

From the viewpoint of sufficiently improving toner cleaning properties and toner filming properties, the molar ratio of m / n is 1/99 or more,
More preferably, it is 5/95 or more.

The polyester resin of the present invention has sufficient strength and flexibility as a binder resin for a photosensitive layer of an electrophotographic photosensitive member. This is not only an electrophotographic photosensitive member having a photosensitive layer formed on a cylindrical substrate having no flexibility but also an electrophotographic photosensitive member having a photosensitive layer formed on a flexible sheet or belt-shaped substrate. Very suitable as a binder resin for the body.

Further, the polyester resin of the present invention has a low surface energy, a large surface contact angle, and good slipperiness. When the layer containing this resin is formed on the surface layer, the occurrence of toner filming in which toner adheres to the surface of the photoreceptor and the occurrence of scratches on the surface are reduced. Since the sliding property with the toner and the transfer paper is good, the wear of the photosensitive member is small, and as a result, the life of the photosensitive member can be prolonged.

Further, the polyester resin of the present invention has excellent compatibility with a charge transfer material, and has a small relative dielectric constant as compared with a polyester containing no fluorine in the molecule because it contains fluorine in the molecule. Since a large carrier mobility can be obtained by these effects, an electrophotographic photosensitive member having high sensitivity and high-speed response can be obtained.

In the present invention, known conductive supports can be used as they are. For example, aluminum, metal or alloy such as stainless steel plate, foil, cylindrical thing,
Alternatively, a sheet, belt, or cylinder formed by depositing a conductive substance such as metal or metal oxide on a plastic film, plate, or cylinder, or applying a dispersion of metal or metal oxide powder in resin Shape.

In the present invention, the photosensitive layer may be a stacked type in which a charge generating substance and a charge transfer substance are separated into respective layers, or a single layer type in which the charge generating substance and the charge transfer substance are contained in the same layer.

In the present invention, a known substance can be used as it is as the charge generating substance. For example, inorganic charge generating substances include selenium, selenium tellurium, selenium-arsenic, cadmium sulfide-selenium, cadmium sulfide, and the like. Examples of organic charge generating substances include pigments and / or pigments such as azo based monoazo, bisazo, and trisazo, phthalocyanine based metal-free phthalocyanine and metal phthalocyanine, polycyclic quinone based anthantrone, perylene based, squarylium based and the like. And the like.

These charge generating substances can be used in combination with various resins and sensitizers as needed.

When the photosensitive layer in the present invention has a layer structure laminated on the charge generation layer and the charge transfer layer, as the resin forming the charge generation layer, in addition to the polyester of the present invention, polyamide,
Examples thereof include polyurethane, polycarbonate, polyvinyl butyral, polyvinyl formal, cellulose acetate-butyrate, polyvinyl acetate, vinyl acetate-vinyl chloride copolymer, and vinyl acetate-vinyl chloride-maleic acid copolymer.

The charge generation layer can be obtained by vapor-depositing the above-mentioned charge generation substance, or by applying and drying a coating liquid in which the above-mentioned charge generation substance and a binder resin are dispersed or dissolved in a solvent.

In the present invention, a known substance can be used as the charge transfer material. For example, pyrazoline derivatives, hydrazone derivatives, stilbene derivatives, oxazole derivatives, oxadiazole derivatives, carbazole derivatives and the like can be mentioned.

The charge transfer layer is obtained by applying and drying a coating solution in which these charge transfer substances are dissolved together with a binder resin. When the charge transfer layer is formed on the surface layer, it is effective to use the polyester of the present invention as a binder resin of the charge transfer layer.

In the electrophotographic photoreceptor of the present invention, when the photosensitive layer has a layer configuration in which the charge generation layer and the charge transfer layer are laminated, the charge generation layer and the charge transfer layer are not clearly separated and the charge generation region The composition may change continuously from the charge transfer region to the charge transfer region.

Further, the charge transfer layer may be formed of two or more layers having different compositions. In this case, the effect can be expected when the polyester of the present invention is used as at least one layer of the binder resin, but it is effective to use the polyester of the present invention as the binder resin of the surface layer. The composition of the charge transfer layer in the thickness direction may not be clearly separated, but may change continuously.

When the charge generation layer is provided on the upper layer, it can be used as a positive charge type, and when the charge transfer layer is provided on the upper layer, it can be used as a negative charge type. When the charge generation layer is formed on the surface layer, it is effective to use the polyester of the present invention as a binder resin of the charge generation layer.

 Next, a method for producing the electrophotographic photoreceptor of the present invention will be described.

In the case of a stacked photoreceptor, the charge generation layer can be formed by a method in which the charge generation material is formed on a substrate by a vacuum deposition method, a sputtering method, a plasma CVD method, or the like, or the charge generation material is dispersed in a binder resin solution. Alternatively, a suitable method can be used from a method in which the composition is dissolved and then applied to a substrate by a dip coating method, a roller coating method, a blade coating method, a spray coating method, and the like, and dried. The thickness of the charge generation layer is preferably from 0.01 to 10 μm, more preferably from 0.05 to 3 μm. When the charge generation layer comprises a charge generation material and a binder resin, the composition ratio of the charge generation material and the binder resin is preferably 1/5 to 5/1 by weight, and more preferably 1/3 to A 3/1 weight ratio is desirable.

As a method for forming the charge transfer layer, the charge transfer substance and the binder resin may be dissolved in a solvent, and then applied and dried by the above-described application method. The thickness of the charge transfer layer is usually 5 to 50 μm,
More preferably, the thickness is 10 to 30 μm. The ratio between the charge transfer material and the binder resin is preferably 20/100 to 200/100 by weight, and more preferably 60/100 to 130 /.
Desirably, the weight ratio is 100.

In the case of a single-layer type, it can be formed by applying and drying a coating solution in which a charge generation material and a charge transfer material and a binder resin or a charge generation material and a binder resin are dissolved and dispersed in a solvent. it can. The thickness of the photosensitive layer is preferably from 5 to 100 μm, and more preferably from 10 to 50 μm. The composition of the charge generating material, the charge transfer material, and the binder resin is preferably in a weight ratio of 1 to 200/0 to 200/100.

In the case of forming an insulating or conductive protective layer, a resin and, if necessary, an additive may be dissolved in a solvent, and applied and dried by the above-described coating method.

[Measurement Method of Characteristics] The electrophotographic characteristics were measured with an electrostatic copying paper test apparatus EPA-8100 (manufactured by Kawaguchi Electric). The sensitivity was indicated by the exposure required to reduce the surface potential by half.

The printing test was performed with a partially modified commercial printer. The scratches on the photoreceptor and the toner filming property were visually and microscopically determined.

The surface contact angle was also measured as an index such as toner cleaning property, toner filming property, and lubricity.

The surface contact angle is desirably 85 degrees or more in order to sufficiently exhibit toner cleaning properties, toner filming properties, and slipperiness.

The surface contact angle was measured using a surface contact angle meter (CA-D type, manufactured by Kyowa Interface Science Co., Ltd.), and water was used as a measurement liquid.

The flexibility of the coating film is polyester film (Toray Industries, Inc.)
The photosensitive layer was wound around cylinders of various diameters and a tension of 500 g / cm was applied to determine whether or not cracks occurred in the coating film.

[Examples] Hereinafter, the present invention will be specifically described based on examples.

Synthesis Example 1 0.57 g (2.5 mmol) of 2,2 was added to 5.1 ml of a 1 M aqueous solution of NaOH.
-Bis (4-hydroxyphenyl) propane and 15 mg of benzyltriethyleneammonium chloride were dissolved. 0.32g dissolved in 5.0ml dichloromethane
(0.5 mmol) of 5- [3,4,4,4-tetrafluoro-2-
[1,2,2,2-tetrafluoro-1- (trifluoromethyl) ethyl] -1,3-bis (trifluoromethyl) -1
-Butenyl] oxyisophthaloyl dichloride, 0.15 g
(0.75 mmol) of isophthaloyl dichloride, 0.38 g
(1.25 mmol) of a mixture of terephthaloyl dichloride was added at once, and the mixture was stirred at 10 ° C. for 30 minutes. The reaction solution was poured into 300 ml of boiling water to which a small amount of hydrochloric acid was added to obtain a white flake polymer.

Yield 97% Intrinsic viscosity 0.83 dl / g (measured at a concentration of 0.5 g / dl in 1,1,2,2-tetrachloroethane at 25 ° C.) Synthesis Example 2 0.57 g in 5.1 ml of 1 M aqueous NaOH solution (2.5m mol) 2,2
-Bis (4-hydroxyphenyl) propane and 15 mg of benzyltriethyleneammonium chloride were dissolved. To this, 0.19 g dissolved in 5.0 ml of dichloromethane
A mixture of (0.5 mmol) of 5-heptafluoropentylisophthaloyl dichloride, 0.15 g (0.75 mmol) of isophthaloyl dichloride, and 0.38 g (1.25 mmol) of terephthaloyl dichloride is added all at once, and the mixture is added at 10 ° C. For 30 minutes. The reaction solution was poured into 300 ml of boiling water to which a small amount of hydrochloric acid was added to obtain a white flake polymer.

Yield 97% Intrinsic viscosity 0.84 dl / g (measured at a concentration of 0.5 g / dl in 1,1,2,2-tetrachloroethane at 25 ° C.) Synthesis Example 3 0.57 g in 5.1 ml of 1 M aqueous NaOH solution (2.5m mol) 2,2
-Bis (4-hydroxyphenyl) propane and 15 mg of benzyltriethyleneammonium chloride were dissolved. 0.875 g dissolved in 5.0 ml of dichloromethane
(2.5 mmol) of 5-heptafluoropropyloxyisophthaloyl dichloride was added, and the mixture was stirred at 10 ° C for 30 minutes.
The reaction solution was poured into 300 ml of boiling water to which a small amount of hydrochloric acid was added to obtain a white flake polymer.

Yield 97% Intrinsic viscosity Measured at a concentration of 0.81 dl / g (0.5 g / dl in 1,1,2,2-tetrachloroethane at 25 ° C.) Example 1 Polyvinyl butyral resin (“Eslec” BL-1, Sekisui Water) 5 parts by weight of Chemical Industry Co., Ltd.) were dissolved in 90 parts by weight of cyclohexanone, 5 parts by weight of titanyl phthalocyanine as a charge generating substance was mixed with this solution, and the mixture was dispersed with a paint shaker for 3 hours. Prepare a charge generation layer coating solution, apply it on an aluminum vapor-deposited film ("Metal Me" manufactured by Toray Industries, Inc.), dry it, and dry it.
A 0.2 μm charge generation layer was formed.

As the binder resin, the polyester 10 obtained in Synthesis Example 1 was used.
Parts by weight was dissolved in 90 parts by weight of 1,2-dichloroethane, and then the compound represented by the formula (VII) was added as a charge transfer material to 1 part by weight.
0 parts by weight were added and dissolved to prepare a charge transfer layer coating solution,
A 20 μm-thick charge transfer layer was formed by coating and drying on the charge generation layer to obtain an electrophotographic photosensitive member.

Example 2 In Example 1, titanyl phthalocyanine was converted to a compound represented by the formula (VI)
An electrophotographic photoreceptor was obtained in the same manner except that the bisazo pigment shown in II) was used.

Example 3 An electrophotographic photosensitive member was obtained in the same manner as in Example 1, except that the charge transfer material was changed to a compound represented by the formula (IX).

Example 4 An electrophotographic photosensitive member was obtained in the same manner as in Example 2, except that the charge transfer material was changed to the compound used in Example 3.

Examples 5 to 8 Examples 5 to 8 were obtained in the same manner as in Examples 1 to 4, except that the binder resin was changed to the polyester obtained in Synthesis Example 2.

Examples 9 to 12 Examples 9 to 12 were obtained in the same manner as in Examples 1 to 4, except that the binder resin was changed to the polyester obtained in Synthesis Example 3.

Comparative Example 1 An electrophotographic photoreceptor was obtained in the same manner as in Example 1, except that the binder resin of the charge transfer layer was changed to polycarbonate (“PANLITE” L-1225, manufactured by Teijin Chemicals Ltd.).

Comparative Example 2 An electrophotographic photoreceptor was obtained in the same manner as in Example 1, except that the binder resin of the charge transfer layer was changed to polymethyl methacrylate (“Acrypet” MD, manufactured by Mitsubishi Rayon Co., Ltd.).

Comparative Example 3 An electrophotographic photosensitive member was obtained in the same manner as in Example 1, except that the binder resin of the charge transfer layer was changed to polyarylate ("U-Polymer" U-100, manufactured by Unitika Ltd.).

Table 1 shows the measurement results of the compatibility, flexibility, surface contact angle, and electrophotographic sensitivity of the charge transfer material and the binder resin of the samples of Examples 1 to 12 and Comparative Examples 1 to 3.

Example 13 Copolymerized nylon (“Amilan” CM8000, manufactured by Toray Industries, Inc.)
Was dissolved in 96 parts by weight of methanol, and this solution was applied on an aluminum tube by a dip coating method and dried.
An undercoat layer having a thickness of 0.3 μm was formed. Next, the coating solution for the charge generation layer prepared in Example 1 was applied onto the undercoat layer by a dip coating method and dried to form a charge generation layer having a thickness of 0.2 μm.

Then, the coating solution for the charge transfer layer prepared in Example 1 was applied on the charge generation layer by a dip coating method, and dried to a thickness of 20 μm.
Was formed to obtain an electrophotographic photosensitive member.

Comparative Example 4 An electrophotographic photoreceptor was obtained in the same manner as in Example 13, except that the coating solution for the charge transfer layer was changed to that used in Comparative Example 3.

After the photoconductors obtained in Example 13 and Comparative Example 4 were mounted on a commercially available remodeled printer and subjected to a 10,000-sheet printing test,
Table 2 shows the results of examination on the scratches on the photoreceptor, the toner filming state, and the background stain state of the printed matter.

[Effects of the Invention] An electrophotographic photosensitive member having cleaning properties such as chemical durability, electrical durability, toner cleaning property and toner filming property, and mechanical durability such as abrasion resistance and scratch resistance according to the present invention. Could provide body.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-132451 (JP, A) JP-A-63-65449 (JP, A) JP-A-63-65451 (JP, A) JP-A 62-65451 215960 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 5/05

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member comprising at least a conductive support and a photosensitive layer, wherein the photosensitive layer comprises a repeating unit represented by the following general formula (I) and a compound represented by the following general formula (I)
An electrophotographic photoreceptor comprising a binder resin composed of a fluorine-containing polyester having a repeating unit represented by I) as a main component. (In the general formulas (I) and (II), X is -O-,-
R is at least one selected from the group consisting of CO-O-, -CO-NH-, and -CO-, and r represents 0 or 1. R ¹ has 1 carbon atom substituted by at least one fluorine atom
And represents an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 1 to 20 carbon atoms substituted by at least one fluorine atom. R ² represents a divalent aromatic group. R ³ represents a divalent organic residue. The molar ratio of m / n is from 1/99 to 100/0. )