JPH09179315A - Positive electrification type electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photoreceptor excellent in mechanical characteristics and ensuring high image quality free from interference fringes as a defect and satisfactory electrical characteristics by incorporating a phthalocyanine compd. or a squarylium compd. into a middle layer. SOLUTION: An electrophotographic photoreceptor consists of a middle layer 6 and a single photosensitive layer 7 consisting of an electric charge generating material 4 and a resin 5 contg. a dissolved or dispersed electric charge transferring material are successively laminated on an electrically conductive substrate 1. A phthalocyanine compd. or a squarylium compd. 2 is incorporated into the resin 3 of the middle layer 6. The amt. of the electric charge generating material 4 contained in the photosensitive layer 7 is regulated to 0.2-5wt.% of the total amt. of the layer 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoconductor, and more particularly to a positive charging type electrophotographic photoconductor having good electrical characteristics, excellent image quality and practically preferable characteristics. .

[0002]

2. Description of the Related Art Generally, an electrophotographic photoreceptor is formed by forming a photosensitive layer made of a photoconductive material on a conductive support. And a charge-transporting layer, and a function-separated type laminated electrophotographic photoreceptor is often used.

In the history of the development of the organic photoreceptor for electrophotography, US Pat. No. 3,484,237 discloses a monolayer of a poly-N-vinylcarbazole / trinitrofluorenone complex which was first put into practical use as an organic compound. Type electrophotographic photoreceptors are disclosed. US Patent 339708
No. 6 describes phthalocyanine resin-dispersed electrophotographic photoconductors, "Journal of Applied Physics", Vol. 49, No. 11, 5543-5564 (1978), etc. , A photoconductor for electrophotography in which a triphenylmethane-based charge transport material is used in combination with a eutectic of a thiapyrylium salt and a polycarbonate resin. As can be seen from these, at the beginning, various single-layer electrophotographic photoconductors were developed, but these single-layer electrophotographic photoconductors were
There were problems such as many restrictions on materials, insufficient sensitivity and durability. Since then, a multi-layer type electrophotographic photoreceptor having a photosensitive layer composed of a charge generation layer and a charge transport layer capable of improving these problems has become widespread. Not in practical use.

However, the layer structure of the multi-layer type electrophotographic photoreceptor is such that a charge transport layer composed of a relatively thick layer is laminated on a charge generation layer of a thin layer of usually 1 μm or less. As the charge-transporting substance used in (1), a substance having a hole-transporting property is generally used because of its abundance of compounds, electrical stability, and safety as a substance. Therefore, in this case, the laminated electrophotographic photoreceptor is
Inevitably, it exhibits sensitivity only when negatively charged.

In recent years, harmful ozone generated from minus corona discharge in the electrophotographic process has become an environmental problem, and it has been desired to commercialize a positively charged electrophotographic photoreceptor which can be used in a plus corona which generates a small amount of ozone. I have. Further, since the positive charging type electrophotographic photoconductor has the same polarity as that of the conventionally used inorganic electrophotographic photoconductors such as a-Se and a-Si, there is an advantage that many peripheral members can be shared. .

In response to the demand for realizing such a practical positive charging type electrophotographic photoconductor, for example, improvement of the conventional single-layer type electrophotographic photoconductor or development of a new electron transporting substance, In addition, although efforts have been made to review the layer structure itself and other efforts have been made, it has not been possible to sufficiently meet the requirements.

[0007] For example, in JP-A-59-49545, charge transport in which a hole transport material is resin-dispersed between a charge generation layer containing a charge generation material and a hole transport material and a conductive support is disclosed. Techniques for providing layers are disclosed. This is basically an attempt to achieve positive charging by reversing the stacking order of the conventional stacking type electrophotographic photoreceptor. In principle, this type of electrophotographic photoreceptor has a hole transport layer provided under a single-layer type electrophotographic photoreceptor of charge generating substance / charge transporting substance / resin dispersion system. The basic characteristics of the electrophotographic photosensitive member are very close to those of a single-layer type electrophotographic photosensitive member having only an upper layer. Further, the upper layer used for the electrophotographic photoreceptor proposed in this publication can be increased in mobility by adding a charge transporting substance to the conventional charge generation layer, and can be made thicker than the conventional one. There is a limit to the number of layers, and in actual continuous use, characteristic changes due to wear of the upper layer are unavoidable, and since a high concentration of charge-generating substances are exposed on the surface, even trace amounts of positive corona discharge occur. The deterioration was large due to adsorption of ozone and nitrogen oxides, and the durability was extremely poor.

As a means for improving the above-mentioned drawbacks of the electrophotographic photoreceptor, for example, "Journal of Imaging Science", No. 28,
Vol. 5, No. 5, pp. 191 to 195 (1984), etc., describes that the content of the charge generating substance in the photosensitive layer of a single layer structure or the charge generating layer provided in the upper layer is extremely reduced. The electrophotographic photoreceptor dispersed in the hole-transporting binder resin is
It has been disclosed. In this case, the content of the charge generating substance is
Since it was extremely low, 5% by weight or less with respect to the photosensitive layer,
There was a merit that a positive charging type electrophotographic photoconductor can be realized which is less affected by surface deterioration and has durability equivalent to that of a conventional laminated type electrophotographic photoconductor.

However, in the single-layer type electrophotographic photoreceptor having the above structure, the amount of the charge generating substance is greatly reduced in order to obtain good sensitivity and durability, so that electrons are sufficiently transported. However, when used in an electrophotographic device such as a laser printer that uses coherent light as an exposure light source, the light reflected by the surface of the photosensitive layer and the photosensitive layer cannot fully absorb it. There is a drawback in that the light reaching the support and reflected by them cause mutual interference, and a ripple-like interference fringe pattern is likely to appear in the image.

[0010]

The problem to be solved by the present invention is to improve various points which have been problems in the practical application of the positively charged type electrophotographic photosensitive member which has been proposed in the past, by the novel photosensitive layer structure. And to provide a positively charged type electrophotographic photoreceptor having favorable performance in terms of electrical and image characteristics.

[0011]

In order to solve the above-mentioned problems, the present invention sequentially forms an intermediate layer and a photosensitive layer having a single layer structure containing a charge generating substance and a charge transporting substance on a conductive support. A positively-charged electrophotographic photoreceptor, wherein the intermediate layer contains a compound having a hole transporting ability and a latent image forming irradiation light absorbing ability in a laminated electrophotographic photoreceptor. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the photosensitive layer of the positive charging type electrophotographic photoreceptor of the present invention is shown in FIG. In FIG. 1, reference numeral 1 is a conductive support, reference numeral 2 is a compound having a hole transporting ability and absorption ability of latent image forming irradiation light, reference numeral 3 is a resin, reference numeral 4
Is a charge generating substance, 5 is a resin in which a charge transporting substance is dissolved or dispersed, 6 is an intermediate layer, and 7 is a photosensitive layer.

As the conductive support, for example, a metal plate, a metal drum, a metal belt using a metal or alloy such as aluminum, copper, zinc, stainless steel, chromium, nickel, molybdenum, vanadium, indium, gold and platinum, Alternatively, a conductive polymer, a conductive compound such as indium oxide, or a metal, an alloy such as aluminum, palladium, or gold coated or vapor deposited or laminated with paper, a plastic film, a belt, or the like can be given.

Examples of the compound having a hole transporting ability and a light absorbing ability for the latent image forming irradiation light used in the intermediate layer include, for example, organic materials such as phthalocyanine compounds, merocyanine compounds, and squarium compounds, or amorphous selenium. , An inorganic material such as crystalline selenium and amorphous silicon can be selected. In particular, in order to correspond to a general semiconductor laser as an exposure light source for image formation, a large absorption power is required for its oscillation wavelength. It is preferable to use a phthalocyanine-based compound, a merocyanine-based compound, or a squarerium-based compound that the compound has.

The proportion of the compound having a hole transporting ability in the intermediate layer and a light absorbing ability for the latent image forming irradiation light is within a range in which the hole transportation in the intermediate layer is sufficient and the transmitted light can be sufficiently absorbed. Therefore, the range in which the film strength can be obtained is preferable. Usually, the ratio of the same material to the total weight of the intermediate layer is 10 to 90% by weight.
Is preferred. If it is less than 10% by weight, holes generated in the photosensitive layer are not sufficiently transported to the conductive support side, the residual potential tends to increase, and light absorption tends to become insufficient, which is not preferable. . Also,
When it is more than 90% by weight, the proportion of the binder in the intermediate layer becomes small, so that mechanical properties such as adhesiveness tend to be insufficient, which is not preferable.

The binder used for the intermediate layer is preferably a high molecular polymer capable of forming an electrically insulating film. Examples of such a high-molecular polymer include polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer,
Vinylidene chloride-acrylonitrile polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinyl carbazole,
Polyvinyl butyral, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenolic resin, polyamide,
Examples include, but are not limited to, carboxy-methylcellulose, vinylidene chloride-based polymer latex, polyurethane, and the like. These binders are used alone or in combination of two or more.

Examples of the charge generating substance used in the photosensitive layer include azo pigments, quinone pigments, perylene pigments, indigo pigments, thioindigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, and quinoline. Series pigments, lake series pigments, azo lake series pigments, anthraquinone series pigments, oxazine series pigments, dioxazine series pigments, triphenylmethane series pigments, azurenium series dyes, squarium series dyes, pyrylium series dyes, triallylmethane series dyes, xanthene series pigments Various organic pigments such as dyes, thiazine dyes, cyanine dyes, dyes, and further amorphous silicon, amorphous selenium,
Inorganic materials such as tellurium, selenium-tellurium alloys, cadmium sulfide, antimony sulfide, zinc oxide, and zinc sulfide can be listed. Among these, titanyl phthalocyanine, or a reaction product of titanyl phthalocyanine and 2,3-butanediol is formed. The thing is especially preferable from the viewpoint of electrical characteristics.

The charge-generating substance used in the photosensitive layer is not limited to those listed here, and when used, it can be used alone, but two or more types of charge-generating substances are mixed and used. You can also

The proportion of the charge generating substance in the photosensitive layer is preferably in the range of 0.2 to 5% by weight based on the total weight of the photosensitive layer. The reason will be described in detail in the section of action.

As the charge transport material used in the photosensitive layer, examples of low molecular weight compounds include pyrene series, carbazole series, hydrazone series, oxazole series, oxadiazole series, pyrazoline series, arylamine series, arylmethane series, Examples thereof include benzidine-based compounds, thiazole-based compounds, stilbene-based compounds, and butadiene-based compounds. Further, as the polymer compound, for example, poly-N-vinyl carbazole,
Examples thereof include halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, and polysilane.

The charge-transporting substance used in the positive charging type electrophotographic photosensitive member of the present invention is not limited to those listed here, and may be used alone or in combination of two or more. You can

The proportion of the charge transporting substance in the photosensitive layer varies depending on the charge transporting ability of the charge transporting substance used, but in the case of a low molecular weight compound, it is in the range of 10 to 60% by weight based on the total weight of the photosensitive layer. preferable. If less than 10% by weight,
Since the charge transport is not sufficiently performed, the sensitivity becomes insufficient and the residual potential tends to increase, which is not preferable, and when it is more than 60% by weight, the content of the resin in the photosensitive layer becomes small, It is not preferable because the mechanical strength of the photosensitive layer tends to decrease. However, when a polymer compound such as poly-N-vinylcarbazole is used as the charge transporting substance, the charge transporting substance itself has a function as a binder, and therefore the entire amount except the charge generating substance may be the charge transporting substance. it can.

In addition to these materials, it is desirable to add an electron-accepting substance to the photosensitive layer in order to effectively prevent the trapping of electrons in the photosensitive layer. As the electron accepting substance, for example, an organic compound such as benzoquinone-based, tetracyanoethylene-based, tetracyanoquinodimethane-based, fluorenone-based, xanthone-based, phenanthraquinone-based, phthalic anhydride-based, diphenoquinone-based You can

As the material used for the binder of the photosensitive layer, the materials mentioned as the binder of the intermediate layer may be used alone or in combination of two or more kinds.

In addition to these binders, additives such as dispersion stabilizers, plasticizers, surface modifiers, antioxidants and photodegradation inhibitors can also be used.

Examples of the plasticizer include biphenyl, biphenyl chloride, terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, polypropylene, polystyrene and various fluorohydrocarbons. Can be mentioned.

Examples of the surface modifier include silicone oil and fluororesin.

Examples of the antioxidant include antioxidants such as phenol type compounds, sulfur type compounds, phosphorus type compounds and amine type compounds.

Examples of the photodeterioration preventing agent include benzotriazole compounds, benzophenone compounds, hindered amine compounds and the like.

When the intermediate layer or the photosensitive layer is formed by dip coating, a mixture of the hole transporting light absorbing material, the charge generating substance, or the charge transporting substance described above with a binder is dissolved in a solvent. Or use a dispersed paint. The solvent for dissolving the binder varies depending on the type of the binder, but is preferably selected from those that do not dissolve the lower layer. Examples of such organic solvents include, for example, methanol,
Alcohols such as ethanol and n-propanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; ethers such as tetrahydrofuran, dioxane and methyl cellosolve; acetic acid Esters such as methyl and ethyl acetate; Sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane; Aliphatic halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and trichloroethane; Benzene, toluene, xylene, monochlorobenzene, dichloro Examples thereof include aromatics such as benzene.

The thickness of the intermediate layer is preferably in the range of 0.1 to 5 μm, and the thickness of the photosensitive layer is preferably in the range of 5 to 50 μm. When the intermediate layer and the photosensitive layer are formed by dip coating, the desired film thickness can be easily obtained by adjusting various properties such as the coating speed, the viscosity of the coating, and the shearing force.

[0032]

The function of the positive charging type electrophotographic photosensitive member of the present invention will be described in detail below, and the reason why the positive charging type electrophotographic photosensitive member of the present invention can exhibit excellent electrical and image quality is clarified. To

In the positive charging type electrophotographic photosensitive member of the present invention, the reason why the concentration of the charge generating substance is made extremely low is that the charge transporting and the charge generating are shared by different materials even though the photosensitive layer has a single layer structure. It is derived from the fact that it is a function-separated type electrophotographic photoreceptor. That is, since the photosensitive layer of the present invention is formed of a matrix in which materials having completely different energy levels of a charge generating substance and a charge transporting substance are dispersed,
The presence of the charge-generating substance acts as a trap for the charge transport, and when the concentration thereof increases, the charge mobility sharply decreases, resulting in deterioration of characteristics. That is, from the viewpoint of charge transport, the lower the concentration of the charge generating substance, the better. On the other hand, if the concentration of the charge-generating substance becomes too low, the absolute amount of the charge-generating substance that contributes to charge generation will be insufficient, so it is necessary to control it to an appropriate value in consideration of these factors. . This proper value varies somewhat depending on the type and dispersion state of the charge generating substance used, but as a ratio of the charge generating substance, relative to the total weight of the photosensitive layer,
A range of 0.2 to 5% by weight is suitable.

In the electrophotographic photoconductor in which the concentration of the charge generating substance is reduced, as described in the section of the prior art, it is inevitable to avoid the generation of interference fringes in the latent image formation by the coherent light. In the electrophotographic photosensitive member of the present invention, the occurrence of interference fringes can be effectively prevented by including a material capable of absorbing the irradiation light transmitted through the intermediate layer. Moreover, since the material used in the present invention also has a hole transporting ability, it has not only a light absorbing effect but also an action of easily injecting holes generated in the photosensitive layer into the conductive support, and thus the electrophotographic photoreceptor There is also a merit that the electric characteristics of are improved.

Further, since the intermediate layer of the electrophotographic photosensitive member of the present invention is not a part directly contributing to the photoelectric conversion of the electrophotographic photosensitive member, it is also a great advantage that the material to be used can have a wide selection range. is there. For example, a compound such as phthalocyanine used as a hole-transporting light-absorbing material can be used as long as it has a light-absorbing ability and a hole-transporting ability even if the compound has insufficient characteristics as a charge-generating substance. Also, as the binder resin, a resin that is completely different from the resin of the photosensitive layer can be used, so a resin such as polycarbonate, which has strong mechanical strength and good electrical characteristics, can be used as an intermediate resin. By using a polyester resin or polyvinyl butyral resin having good adhesiveness for the layer, the electrophotographic photoreceptor can also realize excellent mechanical properties satisfying both strength and adhesiveness at the same time.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the examples. In addition, "part" in the following synthetic examples, examples and comparative examples means "part by weight".

(Synthesis Example 1) 20 parts of β-type titanyl phthalocyanine and (2R, 3R) -2,3-butanediol 2.
Two parts were reacted in 240 parts of α-chloronaphthalene with stirring at 200 ° C. for 1.5 hours. After cooling the reaction mixture to room temperature, the reaction product was filtered off, washed with benzene, methanol, dimethylformamide and water in this order, and then dried under reduced pressure to obtain a phthalocyanine compound.

The phthalocyanine compound thus obtained has a mass spectrum of m / Z = 648 and m / Z = 648.
Since a peak was shown at Z = 576, the formula (1)

[0039]

Embedded image

It was found to be a mixed composition of the compound represented by and unreacted titanyl phthalocyanine.

The X-ray diffraction spectrum of Cu-Kα of this composition is shown in FIG.

As can be seen in FIG. 2, the composition has a Bragg angle of 2θ of 8.3 °, 24.7 ° and 25.1.
It had a strong peak characteristic of °.

Example 1 A resin solution containing 1 part of polyvinyl butyral resin (“S-REC BM-1” manufactured by Sekisui Chemical Co., Ltd.) and 50 parts of methylene chloride was mixed with 2 parts of X-type metal-free phthalocyanine, and It was dispersed for 6 hours using a ball mill to obtain a coating material A for the intermediate layer.

Using this paint A, the thickness of the film after drying was 0.5 μm on the outer peripheral surface of an aluminum drum having a diameter of 30 mm.
After being applied by dipping, the intermediate layer was formed by heating and drying at 100 ° C. for 10 minutes.

Next, 0.3 part of the phthalocyanine composition obtained in Synthesis Example 1 and the formula (2)

[0046]

Embedded image

10 parts of the arylamine compound represented by and 14 parts of a polycarbonate resin ("Iupilon Z-200" manufactured by Mitsubishi Gas Chemical Co., Inc.) were dissolved in 76 parts of chloroform and dispersed using a vibration mill to prepare a photosensitive layer. Paint B
It was created.

This coating material B is applied onto the above intermediate layer by dip coating so that the film thickness after drying is 20 μm, and then dried to form a photosensitive layer, which is a drum-shaped positive charging type. An electrophotographic photoreceptor was obtained.

Example 2 1 part of β-type titanyl phthalocyanine and polyester resin (“Byron-manufactured by Toyobo Co., Ltd.”)
200 ") was mixed with 50 parts of chloroform and dispersed for 1 hour using a sand mill to obtain a coating material C for the intermediate layer.

In Example 1, a paint C for the intermediate layer was used instead of the paint A for the intermediate layer, and the film thickness after drying was 0.8.
A positive charging type electrophotographic photoconductor was obtained in the same manner as in Example 1 except that the intermediate layer was formed to have a thickness of μm.

(Example 3) 1 part of ε-type copper phthalocyanine and phenoxy resin (“PKH” manufactured by Union Carbide Co., Ltd.)
H ") 1 part to 1-acetoxy-2-methoxyethane 2
The mixture was mixed with a mixed solvent of 5 parts and 25 parts of methyl ethyl ketone and dispersed for 1 hour using a sand mill to prepare a coating D for the intermediate layer.

In Example 1, a paint D for the intermediate layer was used instead of the paint A for the intermediate layer, and the film thickness after drying was 0.5.
A positive charging type electrophotographic photoconductor was obtained in the same manner as in Example 1 except that the intermediate layer was formed to have a thickness of μm.

Example 4 A coating material E for the intermediate layer was obtained in the same manner as in Example 3 except that 1 part of chloroindium phthalocyanine was used instead of the ε-type copper phthalocyanine.

In Example 1, a paint E for the intermediate layer was used in place of the paint A for the intermediate layer, and the film thickness after drying was 0.4.
A positive charging type electrophotographic photoconductor was obtained in the same manner as in Example 1 except that the intermediate layer was formed to have a thickness of μm.

Comparative Example 1 Formula (2) used in Example 1
And 10 parts of the arylamine compound represented by
A coating material G for the charge transport layer was obtained by dissolving 14 parts of the polycarbonate resin used in 1) in 76 parts of chloroform.

This coating material G was applied by dip coating to the outer peripheral surface of the same aluminum drum as used in Example 1 so that the film thickness after drying was 10 μm, and then dried to form a charge transport layer. Was formed.

Next, the paint B is applied onto the charge transport layer.
It was applied by a ring coating method so that the film thickness after drying was 10 μm, and then dried by heating to prepare a positive charging type laminated electrophotographic photoreceptor.

(Comparative Example 2) In Example 1, the intermediate layer was not provided directly on the outer peripheral surface of the aluminum drum.
A single-layer type electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the photosensitive layer was provided.

(Comparative Example 3) 1 part of a polyamide resin ("CM-8000" manufactured by Toray Industries, Inc.), 7 parts of methanol and n-
A coating material H was obtained which was composed of a resin solution dissolved in a mixed solvent containing 7 parts of butanol.

In the same manner as in Example 1 except that a barrier layer made of this coating material H having a thickness of 1 μm was provided in place of the intermediate layer and a photosensitive layer was provided on the barrier layer. A positive charging type electrophotographic photoreceptor was obtained.

Comparative Example 4 The aluminum drum used in Example 1 was anodized to form a porous oxide film having a thickness of 6 μm on the surface, and then a sealing treatment was performed with nickel acetate.

In Example 1, an aluminum drum that had been subjected to anodizing treatment and sealing treatment was used, and from the coating material B for the photosensitive layer directly without providing an intermediate layer on the outer peripheral surface of this aluminum drum. Except that a photosensitive layer consisting of
In the same manner as in Example 1, a single-layer type electrophotographic photoreceptor was obtained.

(Electrical Properties) In order to evaluate the electrical properties of the electrophotographic photoconductors obtained in each of the examples and comparative examples, each electrophotographic photoconductor was tested with an electrophotographic photoconductor testing device (manufactured by Gentec). "Cynthia-30") was used to measure the electrophotographic characteristics. The measuring method was as follows. First, the electrophotographic photosensitive member was charged at a voltage of +6 kV by corona discharge while rotating at 60 rpm in the dark, and the surface potential immediately after this was used as the initial potential V ₀ for evaluation of the charging ability. Then 10 in the dark
The potential after standing for 2 seconds was measured and defined as V ₁₀ . here,
The potential holding ability was evaluated by V ₁₀ / V ₀ . Then 7
The exposure intensity on the surface is 1μ with monochromatic light of 80 nm.
Set to be W / cm ^2, for 15 seconds with light irradiation in the photosensitive layer, was recorded decay curve of the surface potential. Here by measuring the surface potential after 15 seconds, was it a residual potential V _R. The surface potential by light irradiation determined amount of exposure until reduced to 1/2 of V _10, were evaluated sensitivity as half decay exposure E _1/2. The results are summarized in Table 1.

[0064]

[Table 1]

As is clear from the results shown in Table 1, the electrophotographic photoconductors obtained in Examples 1 to 4 of the present invention exhibited excellent charging ability and sensitivity. In addition, the phthalocyanine compound used for the intermediate layer, like the copper phthalocyanine used in Example 3, shows a property comparable to that of other phthalocyanines even though it is extremely inferior as a charge generating material. The points are notable. On the other hand, the positive-charge type electrophotographic photoconductors obtained in Comparative Example 1 having a conventional structure in which a thick hole transport layer was provided instead of the intermediate layer were compared with the electrophotographic photoconductors obtained in the respective examples. , The sensitivity was significantly inferior. It is considered that this is because the thickness of the charge transport layer occupies half the thickness of the photosensitive layer, and as a result, the thickness of the layer containing the charge generating substance cannot be made large, resulting in insufficient charge generation. Further, the electrophotographic photoreceptor obtained in Comparative Example 2 in which the intermediate layer was not provided was inferior in potential holding ability and sensitivity to the electrophotographic photoreceptors obtained in the respective examples. Further, the electrophotographic photoconductors obtained in Comparative Examples 3 and 4 in which a barrier layer was provided instead of the intermediate layer had a slight improvement in charging property as compared with the electrophotographic photoconductors obtained in Comparative Example 2. I saw it,
The sensitivity and residual potential were inferior to those of the electrophotographic photoreceptors obtained in the respective examples.

(Practical Characteristics) As an evaluation of image characteristics, a commercially available laser printer (“HL-66” manufactured by Brother Industries, Ltd.) corresponding to a positive charging type drum-shaped electrophotographic photoreceptor is used.
0 ”), a prototype drum-shaped electrophotographic photosensitive member was mounted, and a printing test was performed in an environment of 23 ° C. and 50% RH to evaluate interference fringes. The evaluation regarding the interference fringe is 2
A halftone dot image having a density of 5% was printed, and the degree of evaluation was evaluated on the basis of the following evaluation criteria in three grades of ○, Δ, and ×. ◯: No interference fringes. Δ: Minor interference fringes are seen. X: Remarkable interference fringes are seen.

Next, in order to evaluate the mechanical strength of the electrophotographic photosensitive member, a cross-cut test was carried out in accordance with JIS-K5400, and the number of remaining 100 squares was measured.
The adhesiveness of the photosensitive layer was evaluated.

The evaluation results of these practical characteristics are summarized in Table 2.

[0069]

[Table 2]

As is clear from the results shown in Table 2, each of the electrophotographic photoreceptors obtained in Examples 1 to 4 was
No interference fringe was observed at all, and a good image was obtained, but the electrophotographic photoreceptors obtained in Comparative Examples 1 to 3 had a very remarkable interference fringe, which was a problem in practical use. Further, in the electrophotographic photosensitive member obtained in Comparative Example 4 in which the surface of the support was anodized, a diffuse reflection surface was formed due to the etching effect, and a slight improvement in the degree of interference fringes was observed, but it was not sufficient yet. However, it was insufficient for application to high-definition images. Also, in the evaluation of adhesiveness, the electrophotographic photoreceptors obtained in Examples 1 to 4 showed extremely good results, whereas the electrophotographic photoreceptors obtained in Comparative Examples 1 and 2 showed adhesiveness. Was very bad and the entire surface was peeled off. Further, although the electrophotographic photoreceptors of Comparative Example 3 in which the resin undercoat layer was provided and Comparative Example 4 in which the support was subjected to the surface treatment showed improved adhesiveness, the electrophotographic photoreceptor of the Example. It was much inferior to.

[0071]

The positive charging type electrophotographic photoreceptor of the present invention comprises:
It is practically preferable because it has excellent mechanical properties, high image quality in which interference fringe defects do not appear, and good electrical properties can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a positive charging type electrophotographic photoreceptor of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conductive support 2 Compound having hole transporting ability and absorption of irradiation light for latent image formation 3 Resin 4 Charge generating substance 5 Resin in which charge transporting substance is dissolved or dispersed 6 Intermediate layer 7 Photosensitive layer

FIG. 2 shows titanyl phthalocyanine and (2
R, 3R) -2,3-butanediol reaction product and unreacted titanyl phthalocyanine mixed composition X
It is a line diffraction spectrum.

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[Procedure amendment]

[Submission date] February 29, 1996

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[0011]

In order to solve the above-mentioned problems, the present invention sequentially forms an intermediate layer and a photosensitive layer having a single layer structure containing a charge generating substance and a charge transporting substance on a conductive support. in electrophotographic photoreceptor obtained by laminating the intermediate layer is off
From Tarocyanine compounds, Squareium compounds
Provided is a positively chargeable electrophotographic photoreceptor, which contains a compound selected from the group consisting of:

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[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the photosensitive layer of the positive charging type electrophotographic photoreceptor of the present invention is shown in FIG. In FIG. 1, reference numeral 1 is a conductive support, reference numeral 2 is a phthalocyanine compound,
A compound selected from the group consisting of squarerium compounds , reference numeral 3 is a resin, reference numeral 4 is a charge generating substance, reference numeral 5 is a resin in which a charge transport substance is dissolved or dispersed, reference numeral 6 is an intermediate layer,
Reference numeral 7 represents a photosensitive layer.

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Intermediate of the positive charging type electrophotographic photoreceptor of the present invention
The layer contains a semiconductor layer that is commonly used as an exposure light source for image formation.
Laser with a large absorption capacity for its oscillation wavelength.
And phthalocyanine having good hole transporting ability
Selected from the group consisting of compounds
Contains compounds that are exposed. Phthalocyanine system here
The compound is a generally known substituted or unsubstituted metal-free or
Means metal phthalocyanine compound
The um-based compound refers to US Pat. No. 3,617,270.
No. 3824099, No. 4140989, etc.
Means a group of disclosed compounds.

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Phthalocyanine compound in the intermediate layer
The proportion of the compound selected from the group consisting of wareium-based compounds is preferably within the range where the hole transport in the intermediate layer is sufficient and the transmitted light can be sufficiently absorbed, and a range in which the film strength is obtained. Usually, the ratio of the same material to the total weight of the intermediate layer is preferably in the range of 10 to 90% by weight. 10% by weight
If it is smaller than the above, holes generated in the photosensitive layer are not sufficiently transported to the conductive support side, the residual potential tends to be large, and light absorption tends to be insufficient,
Not preferred. On the other hand, if it is more than 90% by weight, the proportion of the binder in the intermediate layer becomes small, and mechanical properties such as adhesiveness tend to be insufficient, which is not preferable.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

In the electrophotographic photoconductor in which the concentration of the charge generating substance is reduced, as described in the section of the prior art, it is inevitable to avoid the generation of interference fringes in the latent image formation by the coherent light. However, in the electrophotographic photoreceptor of the present invention, the phthalocyanine-based compound, sucrose, which has the ability to absorb the irradiation light transmitted through the intermediate layer is used.
By containing a compound selected from the group consisting of aerium compounds, it is possible to effectively prevent the generation of interference fringes. Moreover, since the material used in the present invention also has a hole transporting ability, it has not only a light absorbing effect but also an action of easily injecting holes generated in the photosensitive layer into the conductive support,
There is also a merit that the electric characteristics of the electrophotographic photoreceptor are improved.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a positive charging type electrophotographic photoreceptor of the present invention.

[Explanation of Codes] 1 Conductive Support 2 Phthalocyanine Compound, Squareium Compound
A compound selected from the group consisting of compounds 3 resin 4 charge generating substance 5 resin in which a charge transporting substance is dissolved or dispersed 6 intermediate layer 7 photosensitive layer

FIG. 2 shows titanyl phthalocyanine and (2
R, 3R) -2,3-butanediol reaction product and unreacted titanyl phthalocyanine mixed composition X
It is a line diffraction spectrum.

Claims (7)

[Claims] 1. A positive charging type electrophotographic photosensitive member comprising an electrically conductive support, and an intermediate layer and a photosensitive layer having a single layer structure containing a charge generating substance and a charge transporting substance, which are sequentially laminated on the conductive support.
A positively chargeable electrophotographic photoreceptor, wherein the intermediate layer contains a compound having a hole transporting ability and a latent image forming irradiation light absorbing ability. 2. The compound having a hole transporting ability and a light absorbing ability contained in the intermediate layer is a compound selected from the group consisting of a phthalocyanine compound, a merocyanine compound and a squarium compound. 1. The positively chargeable electrophotographic photoreceptor according to 1. 3. The positive electrode according to claim 1, wherein the proportion of the charge generating substance contained in the photosensitive layer is in the range of 0.2 to 5% by weight based on the total weight of the photosensitive layer. Charge type electrophotographic photoreceptor. 4. The charge-generating substance contained in the photosensitive layer is titanyl phthalocyanine, and titanyl phthalocyanine and 2,
4. The positively chargeable electrophotographic photoreceptor according to claim 1, wherein the material is at least one material selected from the group consisting of reaction products with 3-butanediol. 5. The positively chargeable electrophotographic photoconductor according to claim 1, wherein the photosensitive layer contains an electron-accepting substance. 6. The positive-charge type electrophotographic photosensitive material according to claim 1, which is used in a positive-charge type electrophotographic apparatus which forms a latent image by exposure with coherent light. body. 7. The positive charging type electrophotographic photoconductor according to claim 6, wherein the electrophotographic apparatus is a laser printer.