JPH036570A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a high sensitivity and to improve the stability to repetitive use by incorporating titanyl phthalocyanine as a charge generating material into a photosensitive layer and incorporating specific compds. as a charge transfer material therein. CONSTITUTION:The titanyl phthalocyanine which exhibits strong diffraction peaks at Bragg angles (2theta+ or -0.2 deg.) 9.7 deg., 15.0 deg., 24.2 deg., and 27.3 deg. in powder X-ray diffraction spectral using CuKalpha rays is incorporated as the charge generating material into the photosensitive layer and at least one kind of the compds. expressed by formula I are incorporated as the charge transfer material into the photosensitive layer. In the formula I, R<1> denotes an alkyl group, aralkyl group, aryl group, etc.; R<2> denotes a group selected from a hydrogen atom, alkyl group and aralkyl group; R<3> denotes an aryl group which may have a substituent. The high sensitivity is obtd. and the stability to the repetitive use is improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an organic electrophotographic photoreceptor suitable for use as a photoreceptor for an optical printer.

[Prior Art] Selenium, cadmium sulfide, zinc oxide, etc. have long been known as photoconductors used in electrophotographic processes. In recent years, organic photoconductors have attracted attention because they have advantages such as low toxicity, good transparency, and the like.

The basic characteristics required of an electrophotographic photoreceptor include good charge acceptance and charge retention in the dark, high sensitivity, low residual potential, and spectral sensitivity appropriate to the intended use. , excellent durability, and good workability. However, among the conventionally proposed organic photoconductors, there are hardly any that satisfy all of these required characteristics using a single material.

Therefore, recently, a layer containing a charge-generating substance that absorbs light and generates charges (charge-generating layer) and a layer containing a charge-transfer substance that moves the generated charges (charge-transfer layer) have been developed on a conductive substrate. A functionally separated photoreceptor with laminated layers has been proposed. This is aimed at improving the characteristics and widening the range of material selection by assigning the two functions of the photoreceptor to different materials.

In functionally separated photoreceptors, charge-generating substances are mainly organic dyes such as bisazo compounds, squarylium dyes, and phthalocyanines, and charge-transfer substances are mainly low-molecular-weight compounds with hole-transfer functions such as hydrazone compounds and pyrazoline derivatives. used.

In recent years, high-speed, high-quality optical printers using an electrophotographic process have been attracting attention as output devices for computers and word processors. Semiconductor lasers are often used as light sources for optical printers due to their miniaturization and cost reduction.

Since the oscillation wavelength of a semiconductor laser is around 800 nm, the photoreceptor used in such an optical printer has a wavelength of 80 nm.
It is necessary to have high sensitivity to light around 0 nm.

[Problems to be Solved by the Invention] Since the spectral characteristics of a functionally separated photoreceptor are mainly determined by the charge-generating substance, it is necessary to use a material that absorbs light with a wavelength of around 800 nm well in the photoreceptor for optical printers. However, the number of organic compounds that absorb such long-wavelength light is quite limited, making it difficult to obtain good materials.

Further, conventional functionally separated photoreceptors for optical printers have had problems such as insufficient sensitivity and significant deterioration of characteristics due to repeated use.

In order to solve these problems, it is necessary to conduct extensive studies not only on charge-generating substances but also on charge-transfer substances.Moreover, in a functionally separated photoreceptor that combines these materials, it is necessary to conduct a wide range of studies on charge-generating substances and charge-transfer substances. Since photoreceptor characteristics are determined by compatibility, more studies need to be conducted to optimize the combination. As a result of extensive research, the present inventors have discovered that a photoreceptor containing a specific charge-generating substance and a charge-transfer substance exhibits particularly excellent characteristics as a photoreceptor for an optical printer, and has arrived at the present invention.

Therefore, an object of the present invention is to provide an electrophotographic photoreceptor for an optical printer that has high sensitivity and excellent stability against repeated use.

[Means for Solving the Problems] The electrophotographic photoreceptor of the present invention includes a conductive layer and a photosensitive layer,
The photosensitive layer contains a charge-generating substance and a charge-transfer substance, and in a powder X-ray diffraction spectrum using CuKa radiation as the charge-generating substance, the black angle (2θ±0.2°) is 9.
7@15.0@.

An electrophotographic image containing titanyl phthalocyanine exhibiting strong diffraction peaks at 24.2° and 27.3°, and containing at least one compound represented by the general formula (I) as the charge transfer substance. It is a photoreceptor.

(In the formula, R1 represents a group selected from an alkyl group that may have a substituent, an aralkyl group that may have a substituent, and an aryl group that may have a substituent, and R2 represents a hydrogen atom,
It represents a group selected from an alkyl group which may have a substituent and an aralkyl group which may have a substituent, and R3 represents an aryl group which may have a substituent. ) The electrophotographic photoreceptor of the present invention has a conductive layer and a photosensitive layer, and the photosensitive layer contains a charge generation substance and a charge transfer substance. The photosensitive layer referred to herein may be a single layer type containing a charge generation substance and a charge transfer substance in a single layer, each layer having a different composition containing at least one of a charge generation substance and a charge transfer substance. It may be of a laminated type in which a plurality of layers are laminated to contain a charge generating substance and a charge transporting substance as a whole. Therefore, the photoreceptor may have the following configurations, for example.

(1) Conductive layer/layer containing charge-generating substance/layer containing charge-transfer substance (2) Conductive layer/layer containing charge-transfer substance/layer containing charge-generating substance (3) Conductive layer/layer containing charge-generating substance Layer containing a substance and a charge transfer substance (4) Conductive layer/layer containing a charge generation substance/layer containing a charge generation substance and a charge transfer substance (5) Conductive layer/layer containing a charge transfer substance/charge generation Layer Containing Substance and Charge Transfer Substance Since ordinary charge transfer substances are of the hole transfer type, when used in the Carlson electrophotographic process, the structure (1)
The photoreceptors of configurations (2) and (5) are positively charged, and the photoreceptors of configurations (3) and (4) are used for both positively and negatively charged photoreceptors.

Photoreceptors with each of the above configurations are manufactured by providing an appropriate intermediate layer between layers to improve adhesion and controlling charge injection, providing a protective layer, an insulating layer, a white layer, etc. on the surface, and increasing the concentration of components in each layer. It can also be changed in the opposite direction.

Although the structure of the photoreceptor of the present invention can be modified in various ways other than the above-mentioned basic structure, the most common one is structure (1). Configuration (1) will be explained in detail below.

Any known conductive layer can be used as the conductive layer in configuration (1). For example, a metal material processed into a predetermined shape is used. Examples of metal materials in this case include aluminum, stainless steel, copper, and the like. Furthermore, a thin film of a conductive material formed on a suitable support may also be used. In this case, examples of the support include glass, resin, paper, cloth, etc., and examples of the conductive material include metals such as aluminum, palladium, rhodium, gold, and platinum, carbon, or tin oxide and oxide. Examples include conductive compounds such as indium tin, polymer electrolytes, and conductive polymers, and examples of forming methods include vapor deposition, sputtering, coating, and lamination. The shape of the conductive layer can be freely selected from flat plate, drum, film, etc. depending on the purpose of use.

The charge generating substance used in the layer containing the charge generating substance of configuration (1), that is, the charge generating layer, has a black angle (2θ
±0.2°) Titanyl phthalocyanine is used which shows strong diffraction peaks at 9.7°, 15.0°, 24.2° and 27.3°.

Such titanyl phthalocyanine is disclosed in, for example, JP-A No. 6
It can be obtained by selecting special heat treatment conditions in a method similar to the treatment method for titanyl phthalocyanine described in Publication No. 3-20365. The treatment method described in this publication is a method in which titanyl phthalocyanine synthesized by a conventional method is treated with an acid paste, suspended in water, added with an aromatic hydrocarbon solvent such as dichlorobenzene, and heat-treated. In the powder X-ray diffraction spectrum of titanyl phthalocyanine subjected to the above treatment, which is listed in the example, no diffraction peaks other than the diffraction peak at black 2θ of 27.3° appear clearly. It can be considered that the crystallinity is low. The heat treatment in this example was carried out at 50 to 60°C for 1 hour, but according to the studies of the present inventors, the heating temperature was as high as 80 to 100°C, and the treatment time was 3 to 5°C. When the time was increased, the crystallinity of titanyl phthalocyanine after treatment improved, and the black angle (2θ ± 0.2°) was 9.7° in the powder X-ray diffraction spectrum.
It was found that clear diffraction peaks also appeared at 15.0° and 24°2°.

Note that the measurement of the powder X-ray diffraction spectrum using CuKa rays can be performed using a 2155D goniometer manufactured by Rigaku Denki Co., Ltd.

As a known example of titanyl phthalocyanine that exhibits a powder X-ray diffraction spectrum similar to that of the titanyl phthalocyanine of the present invention, there is a titanyl phthalocyanine crystal obtained by hydrothermal treatment described as type ■ in JP-A No. 62-67094. . However, the powder X described in the publication
In the line diffraction spectrum, 9.7° 15.0°
Diffraction peaks with small Black angles, such as , do not clearly appear, and the crystallinity is considered to be low. Moreover, looking at the measurement results of electrophotographic properties in this publication, it is found that type 2 titanyl phthalocyanine does not provide very good properties as a charge generating material. On the other hand, since the titanyl phthalocyanine of the present invention exhibits very excellent electrophotographic properties as shown in the examples, it is considered that the effect of improving crystallinity has resulted in a very large improvement in electrophotographic properties. It will be done.

In addition to the above titanyl phthalocyanine, other known charge generating substances may be added to the charge generating layer.

The charge generation layer is formed by applying a paint in which a charge generation substance is dispersed in a solvent, or a paint in which a charge generation substance and a suitable binding resin are dispersed in a solvent, on the conductive layer. If the coating amount of the charge generation layer is too large, the chargeability and repetition stability will be lowered, and if it is too small, the sensitivity will be lowered.

The preferred coating amount of the charge generation layer is 0.01 to 1 g/Cm2.
It is.

When the charge generation layer is composed of a charge generation substance and a binding resin, a known binding resin can be used. Preferably used binding resins include the following.

Polyamide, polyester, polyurethane, polyimide, polycarbonate, polyarylate, polyacetal, polyethylene oxide, polypropylene oxide, polymethacrylate, polyacrylate, polystyrene, polyvinyl acetate, polyvinyl chloride, alkyd resin, butyral resin, silicone resin, Examples include, but are not limited to, epoxy resins and urea resins. These binding resins may be used alone or in a mixed system of two or more types (or may be a copolymer).

Further, crosslinking may be carried out by adding a suitable crosslinking agent.

When using a binding resin, the weight ratio of the charge generating substance to the binding resin is 110 from the viewpoint of film strength, adhesion and sensitivity.
．． It is preferable to set it to 2 to 1/2.

The layer containing a charge transfer substance in configuration (1), that is, the charge transfer layer, contains at least one compound represented by the general formula (1) as a charge transfer substance.

Various known olefin synthesis reactions can be used as a method for synthesizing the compound represented by general formula (I), but in the study of the inventors, the carbonyl compound represented by general formula (II) below is reductively trimerized. It has been found that the method of obtaining the compound represented by the general formula (I) is the simplest and best.

(In the formula, R1, R2, and R3 have the same meanings as in general formula (I).) Examples of reagents used for reductive dimerization include Tic13
-LiAlH4, TiCl4-Zn, etc. (
New Experimental Chemistry Course 14 Synthesis and Reactions of Organic Compounds 1,207
(see page).

In this reaction, the product is often a mixture of geometric isomers, but even in that case, the electrophotographic properties do not change much whether the isomers are isolated and used as a mixture, so it is not necessary to use isomers. It is not necessary to separate the

Substituents R1, R2, and R3 in general formula (I) are preferably substituents as described below.

When the substituent R1 or R2 is an alkyl group, it preferably has 1 to 20 carbon atoms, and may be linear or branched. When this further has a substituent, preferable substituents include a halogen atom, an alkoxy group, an aryloxy group, and a disubstituted amino group. When the substituent R1 or R2 is an aralkyl group, the aralkyl group represents an alkyl group substituted with one or more aryl groups, and preferably has 7 to 20 carbon atoms.

When this further has a substituent, preferred substituents include a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, and a di-substituted amino group. When substituent R1 or R2 is an aryl group, it preferably has 6 to 16 carbon atoms. In addition, when this further has a substituent, preferable substituents include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group,
Examples include a disubstituted amino group and a divalent group such as a methylenedioxy group.

Next, specific examples of the charge transfer substance represented by the general formula (I) are shown below. However, the present invention is not limited to these.

The charge transfer substance represented by the formula (I) may be used alone or in combination of two or more types, or may be used together with other known charge transfer substances.

The charge transfer layer is formed by dissolving or dispersing the charge transfer substance and a suitable binding resin in a suitable solvent and applying a coating material on the charge generation layer. Preferably used binding resins include the same resins as exemplified in the section of the charge generation layer. A preferable weight ratio of the charge transfer substance and the binding resin in the charge transfer layer is 110.0% from the viewpoint of sensitivity, response speed, and film strength.
It is preferable to set it to 2 to 1/2. If the thickness of the charge transfer layer is too thin, the charging ability of the photoreceptor will decrease, and if it is too thick, the response speed will decrease and the residual potential will increase.

The thickness of the charge transfer layer is preferably 5 to 30 μm, more preferably 10 to 25 μm.

Further, an antioxidant, an ultraviolet absorber, and the like can be added to this charge transfer layer in order to improve durability, repetition stability, and the like.

Next, photoreceptor configurations other than configuration (1) will be described.

The conductive layer, the layer containing a charge transfer substance, and the layer containing a charge generation substance in configuration (2) are the same as the corresponding layers in configuration (1), except that the stacking order is different. .

The conductive layer in configuration (3) is the same as the conductive layer in configuration (1). The layer containing a charge transfer substance and a charge generation substance in configuration (3) is formed by applying a paint in which a charge transfer substance, a charge generation substance, and a binding resin are dispersed in a solvent onto the conductive layer. Ru. If the core layer is too thin, the charging ability of the photoreceptor will be reduced, and if it is too thick, the response speed will be reduced. The preferred thickness of the nuclear layer is 5
~30 μm. The charge transfer substance, charge generation substance, and binding resin used here are the same as those used in configuration (1). If the weight ratio of the charge-generating substance to the charge-transfer substance in the layer is too small, the sensitivity will be lowered, and if it is too large, the chargeability will be lowered and the stability against repetition will be lowered. The preferred weight ratio of charge generating material to charge transporting material in the layer is 1/2 to 1/1000. Furthermore, if the weight ratio of the charge transfer substance to the binding resin in the layer is too small, the sensitivity and response speed will be reduced, and if it is too large, the film strength will be reduced. The preferred weight ratio of charge transport material to binding resin in the layer is 110.
．． It is 2 to 1/2.

The conductive layer and the layer containing a charge-generating substance in configuration (4) are the same as the corresponding layers in configuration (1), and the layer containing the charge-generating substance and charge-transfer substance in configuration (4) is the same as the corresponding layer in configuration (1). The same layer as the corresponding layer in (3) is used.

The conductive layer and the layer containing a charge transfer substance in configuration (5) are the same as the corresponding layers in configuration (1). The layer containing the charge-generating substance and the charge-transfer substance in configuration (5) has the same composition as the corresponding layer in configuration (3). If the thickness of the core layer is too thick, the chargeability and repetition stability will be lowered, and if it is too thin, the sensitivity will be lowered. The preferred thickness of the core layer is 0.1~
It is 10 μm.

Between the photosensitive layer and the conductive layer mentioned above, there is a need to improve adhesion,
A suitable intermediate layer can be provided for controlling charge injection.

Further, a surface layer can be provided on the surface of the photosensitive layer for the purpose of improving durability.

[Example] The present invention will be explained below based on examples.

[Method of Measuring Photoreceptor Characteristics] Corona charging was performed at 15 kV in a static manner using an electrostatic copying paper tester EPA-8100 manufactured by Kawaguchi Electric.
After being kept in a dark place for 5 seconds, it was exposed to light with a wavelength of 80 Qnm at an illuminance of 1 μW/cm 2 for 5 seconds, and the time change in surface potential was measured to determine the half-reduction exposure amount E% (μJ/cm 2 ).

Example 1 1 part of crude titanyl phthalocyanine synthesized from phthalonitrile and titanium tetrachloride by a conventional method was dissolved in 30 parts of concentrated sulfuric acid, and this was poured into 500 parts of water to precipitate crystals, which were collected by filtration and washed with water. Next, this was added to 5 parts of water, 1 part of O-dichlorobenzene was added, and the mixture was heated and stirred at 100°C for 3 hours.
The crystals were collected by filtration, washed with water, and dried.

Cu of the titanyl phthalocyanine crystal obtained in this way
A powder X-ray diffraction spectrum using Ka rays is shown in FIG. A 2155D goniometer manufactured by Rigaku Denki Co., Ltd. was used for the measurement.

Next, an aluminum vapor-deposited polyester film ("Metal Me"#75, Toshishiku Co., Ltd.)) was used as a conductive layer, and 10 parts of titanyl phthalocyanine obtained by the above method and a polyvinyl butyral resin ("S-LEC" BL-1) were then applied as a conductive layer.
, Tanezu Kagaku Co., Ltd., dispersed in cyclohexanone to a solid content concentration of 2.5% by weight, was applied with a wire bar to a coating amount of 0.15 g/cm2, and charged. A generation layer was formed.

Next, 10 parts of the charge transfer substance (I-7) shown in the specific example, 1 part of "Panlight" L-1225 (manufactured by Kijin Kasei Co., Ltd.)
A paint prepared by dissolving 0 parts in 1,2-dichloroethane to a solid concentration of 20% by weight is applied onto the charge generation layer using a wire bar to a film thickness of 20 μm, and charge transfer is performed. formed a layer.

The results of measuring the half-decrease exposure amount of the photoreceptor thus obtained under the above conditions are shown below.

E3A=0.25 pJ/cm2 Comparative Example 1 α-type titanyl phthalocyanine was obtained by the method described in Example 1 of JP-A-61-239248. FIG. 2 shows the powder X-ray diffraction spectrum of this α-type titanyl phthalocyanine using CuKa radiation.

Next, a photoreceptor was prepared in the same manner as in Example 1 except that the α-type titanyl phthalocyanine was used as the charge generating substance. The measurement results of the half-decreased exposure amount of this photoreceptor were as follows.

E3A=0.40aJ/cm2 Comparative Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that the charge transfer substance was changed to a hydrazone compound represented by the following formula.

The measurement results of the half-decreased exposure amount of this photoreceptor were as follows.

EH=0.44 μJ/am” Examples 2 to 19 Example 1 except that the charge transfer substance was changed to those shown in the table.
Table 1 shows the characteristics of the photoreceptor prepared in the same manner as above.

) × Lower Table 1 Table 1 2θ No-Hanging Example 20 A photoreceptor drum was prepared by forming a photoreceptor layer substantially the same as that of the photoreceptor prepared in Example 1 on an aluminum drum. This was installed in a commercially available laser printer and a printing test was performed 5000 times. Even after printing 5000 times, clear printing was obtained without deterioration in print quality.

[Effects of the Invention] As is clear from the above examples, the present invention provides an electrophotographic photoreceptor with high sensitivity, excellent stability against repeated use, and suitable for use in electrophotographic processes such as optical printers. be able to.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an X-ray diffraction spectrum of titanyl phthalocyanine used in the present invention, and FIG. 2 is a diagram showing an X-ray diffraction spectrum of a conventional titanyl phthalocyanine.

Claims (1)

[Claims] Comprising a conductive layer and a photosensitive layer, the photosensitive layer contains a charge generation substance and a charge transfer substance, and the charge generation substance is CuK.
Black angles (2θ±0.2°) of 9.7°, 15.0°, 24.2 in the powder X-ray diffraction spectrum using α-rays
An electrophotographic photoreceptor comprising titanyl phthalocyanine exhibiting strong diffraction peaks at 27.3° and 27.3°, and at least one compound represented by formula (I) as the charge transfer substance. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R^1 is an alkyl group that may have a substituent, an aralkyl group that may have a substituent, or an aralkyl group that may have a substituent. R^2 represents a group selected from a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, and R^3 represents a group selected from a substituent. (Represents an aryl group that may have a group.)