Phthalocyanine crystal and its production, and electrophotosensitive material using the same

Abstract

Disclosed are a phthalocyanine crystal in which an organic acceptor compound is associated with a phthalocyanine molecule, wherein said organic acceptor compound has a reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V, and an electrophotosensitive material containing said phthalocyanine crystal as an electric charge generating material, which exhibits sufficient photosensitivity even in high-speed image forming apparatuses.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a phthalocyanine crystal associating with an organic acceptor compound, its production method, and a high-sensitivity electrophotosensitive material containing the same.

With the development of a non-impact printer technique, an electrographic photoprinter using laser beam or LED as a light source,which is capable of attaining high image quality and high speed, has widely been used and a photosensitive material which responds to the demands has intensively been developed, recently. Among these photosensitive materials, an organic photosensitive material has widely been used because of its easy production, wide range of choice of photosensitive materials and high functional design freedom as compared with a conventional inorganic photosensitive material.

The organic photosensitive material includes, for example, single-layer type photosensitive material wherein an electric charge transferring material is dispersed in the same photosensitive layer, together with an electric charge transferring material, and function-separation type multi-layer type photosensitive material comprising an electric charge generating layer containing an electric charge generating material and an electric charge transferring layer containing an electric charge transferring material, which are mutually laminated.

When using a laser as a light source, a semiconductor laser is exclusively used because of its small size, cheap price, and simplicity. The oscillation wavelength of the semiconductor laser is not less than 750 nm at present and is limited to an infrared range. Accordingly, an organic photosensitive material having the sensitivity at a wavelength within a range from 750 to 850 nm is required.

As the electric charge generating material used in the organic photosensitive material, which satisfies the above demands, for example, polycyclic quinone pigment, pyrylium dye, squarium pigment, phthalocyanine pigment, and azo pigment have been suggested or put into practice.

Among the above electric charge generating materials, most popular phthalocyanine pigments include, for example, metal-free phthalocyanine having no center metal and metallic phthalocyanine having a center metal, and they have various crystal forms such as α, β, and γ forms. The presence or absence and kind of the center metal as well as crystal form exert a large influence on the charging properties and sensitivity of the photosensitive material.

As the method of attaining a high-sensitivity photosensitive material using phthalocyanine, for example, a method of adding an organic acceptor compound in a photosensitive material has been studied. Japanese Unexamined Patent Publication (Kokai) No. 7-104495 describes a method of adding an organic acceptor compound in an electric charge generating layer of a multi-layer photosensitive material, while Japanese Unexamined Patent Publication (Kokai) No. 6-123984 describes a method of adding an organic acceptor compound in a binder of a single-layer photosensitive material.

However, any of the above methods is a method of adding an organic acceptor compound in the production process of a photosensitive material, that is, a method of adding an organic acceptor compound in the production process of a coating solution for photosensitive layer. A high-speed image forming apparatus has such a problem that the photosensitivity of its photosensitive material is poor, and a further improvement in photosensitivity is required.

SUMMARY OF THE INVENTION

Thus, an object of the present invention is to provide a novel phthalocyanine crystal useful as an electric charge generating material, and a production method thereof.

Another object of the present invention is to provide an extra-high-sensitivity electrophotosensitive material containing the above phthalocyanine crystal.

The present inventors have intensively studied to attain the above object and found that a photosensitive material containing, as an electric charge generating material, a phthalocyanine crystal produced by adding an organic acceptor compound in a photosensitive layer during the step of converting into a pigment, not produced by merely adding the organic acceptor in the photosensitive layer.

Thus, the present inventions relate to:

1. A phthalocyanine crystal in which an organic acceptor compound whose reduction potential to a reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V is associated with a phthalocyanine molecule.

2. The phthalocyanine crystal according to the above item 1, wherein said phthalocyanine is a metal-free phthalocyanine.

3. The phthalocyanine crystal according to the above item 1, wherein said phthalocyanine is a metal phthalocyanine represented by the general formula (1):

 wherein M is a metal of the groups IIa, IIIa, IVa, Va, VII, Ib, IIb, IIIb, IVb or VIb on the periodic table, or a group containing the metal.

4. The phthalocyanine crystal according to the above item 3, wherein the group containing the metal is in the form of oxide, hydroxide, halide or cyanide.

5. The phthalocyanine crystal according to the above item 3, wherein M is TiO.

6. The phthalocyanine crystal according to the above item 1, wherein a solubility of said organic acceptor compound in a solvent in a coating solution for photosensitive layer is less than 10% by weight.

7. The phthalocyanine crystal according to the above item 6, wherein said solvent in a coating solution for photosensitive layer is alcohols, ketones or ethers.

8. The phthalocyanine crystal according to the above item 1, wherein said organic acceptor compound contains a compound represented by the general formula (2):

 wherein R 1 , R 2 , R 3 and R 4 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R 1 and R 2 , or R 3 and R 4 may be combined with each other to form a ring.

9. The phthalocyanine crystal according to the above item 1, wherein said organic acceptor compound contains a compound represented by the general formula (3):

 wherein R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 and R 12 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R 5 and R 6 , R 7 and R 8 , R 9 and R 10 , or R 11 and R 12 may be combined with each other to form a ring; and A 1 represents a saturated or unsaturated alkyl group which may have a substituent, an aryl group, or a heterocycle which may have a substituent.

10. The phthalocyanine crystal according to the above item 1, wherein said organic acceptor compound contains a compound represented by the general formula (4):

 wherein X 1 , X 2 , X 3 and X 4 are the same or different and each represents an oxygen atom or C(CN) 2 ; R 13 , R 14 and R 15 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent; and Y 1 and Y 2 are the same or different and each represents a carbon atom, an oxygen atom, or a nitrogen atom.

11. The phthalocyanine crystal according to the above item 1, wherein said organic acceptor compound contains a compound represented by the general formula (5):

 wherein X 5 and X 6 are the same or different and each represents an oxygen atom or C(CN) 2 ; and R 16 , R 17 and R 18 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R 16 and R 17 may be combined with each other to form a ring.

12. A phthalocyanine crystal in which an organic acceptor compound is associated with a phthalocyanine molecule, which is produced by adding the organic acceptor compound whose reduction potential to a reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V during a step of converting into a pigment.

13. A method of producing a phthalocyanine crystal in which an organic acceptor compound is associated with a phthalocyanine molecule, a step of which comprises: dissolving said phthalocianine together with said organic acceptor compound whose reduction potential to a reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V in a solvent capable of dissolving both of said phthalocyanine and said organic acceptor compound, adding the resulting solution to an aqueous methanol, thereby crystallizing said phthalocyanine associated with said organic acceptor compound.

14. An electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the photosensitive layer contains the phthalocyanine crystal of the above item 1 as an electric charge generating material.

15. An electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the photosensitive layer contains the phthalocyanine crystal of the above item 12 as an electric charge generating material.

16. The electrophotosensitive material according to the above item 14 or 15, which is a single-layer photosensitive material a layer of which comprises dispersing said phthalocyanine crystal and at least one of a hole transferring material and an electron transferring material into a binder resin.

17. The electrophotosensitive material according to the above item 16, wherein said single photosensitive layer contains both of the hole transferring material and the electron transferring material.

18. The electrophotosensitive material according to the above item 16, wherein said single photosensitive layer is formed by coating a coating solution which comprises adding said phthalocyanine crystal, at least one of the hole transferring material and the electron transferring material, and the binding resin to an organic solvent, and then drying the coated layer.

19. The electrophotosensitive material according to the above item 14 or 15, wherein said photosensitive layer is a laminated photosensitive layer which comprises laminating an electric charge generating layer containing said phthalocyanine crystal and an electric transferring layer containing at least one of a hole transferring material and an electron transferring material into a binder resin.

20. The electrophotosensitive material according to the above item 19, wherein said electric charge generating layer is formed by coating a coating solution which comprises adding said phthalocyanine crystal and the binding resin to an organic solvent, and then drying the coated layer.

21. The electrophotosensitive material according to the above item 16 or 19, wherein said binder resin contains a bis-Z type polycarbonate resin.

An electrophotosensitive material according to the present invention exhibits extra-high sensitivity. For example, it becomes possible to use the electrophotosensitive material even in high-speed image forming apparatuses because of its sufficient photosensitivity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph showing a relationship between the reduction potential (V) of an organic acceptor compound and the potential after exposure V L (V) of a single-layer type photosensitive material (hole transferring material: HT-1, electron transferring material: ET-1).

FIG. 2 is a graph showing a relationship between the solubility (% by weight) of an organic acceptor compound to THF and the potential after exposure V L (V) of a single-layer type photosensitive material (hole transferring material: HT-1, electron transferring material: ET-1). In a single-layer type photosensitive material using a hole transferring material HT-1 and an electron transferring material ET-1, the case where V L is not more than 150 V was rated “pass”, whereas, the case where V L exceeds 150 V was rated “fail”. The double line in the drawing means this boundary value.

FIG. 3 is a graph showing a relationship between the reduction potential (V) of an organic acceptor compound and the potential after exposure V L (V) of a multi-layer type photosensitive material (hole transferring material: HT-1).

FIG. 4 is a graph showing a relationship between the solubility (% by weight) of an organic acceptor compound to THF and the potential after exposure V L (V) of a multi-layer type photosensitive material (hole transferring material: HT-1). In a single-layer type photosensitive material using a hole transferring material HT-1, the case where V L is not less than −150 V was rated “pass”, whereas, the case where V L is less than −150 V was rated “fail”. The double line in the drawing means this boundary value.

MODE FOR CARRING OUT THE INVENTION

According to the present invention, a photosensitive material containing, as an electric charge generating material, a phthalocyanine crystal which comprises associating with an organic acceptor compound in a photosensitive layer exhibits extra-high sensitivity. Said phthalocyanine crystal is produced during the step of converting into a pigment, not produced by merely adding the organic acceptor in the photosensitive layer. The reason is assumed as follows.

In the phthalocyanine crystal produced by adding the organic acceptor compound during the step of converting into a pigment, phthalocyanine molecules and organic acceptor compound molecules are associated in a molecular state and then crystallized as they are, so that an intermolecular distance of both molecules in the photosensitive layer is very small and both molecules are dispersed in the state where they are associated, which leads to the state where the organic acceptor compound is contained in the phthalocyanine crystal. It is, therefore, considered that the photosensitive material exhibits extra-high sensitivity because giving and receiving of electric charges generated in phthalocyanine are carried out very smoothly.

On the other hand, in the method of adding the organic acceptor compound during the step of preparing the coating solution for photosensitive layer, an intermolecular distance of both molecules in the photosensitive layer is comparatively long and, furthermore, crystallization and poor dispersion of the organic acceptor compound molecules occur and giving and receiving of electric charges are not carried out smoothly.

An organic acceptor compound in the present invention is an organic compound capable of acting as an electron acceptor. The organic acceptor compound is capable of forming associating molecules with phthalocyanine molecules. As described in the above item 1, it is necessary that the reduction potential of the organic acceptor to the reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V. When the reduction potential of the organic acceptor potential is less than−1.5 V, the photosensitivity does not exhibit high sensitivity because of too weak acceptability. When the reduction potential of the organic acceptor potential is more than −0.5 V, the charging properties and sensitivity of the photosensitive material are drastically lowered because an increase in thermal carrier is caused by formation of a complex of the phthalocyanine and organic acceptor compound.

The reduction potential of the organic acceptor compound was determined by a cyclic voltammetry. The measurement conditions are shown below.

Work electrode: glassy carbon

Counter electrode: platinum

Reference electrode: silver/silver nitrate (0.1 mol/1AgNO 3 -acetonitrile solution)

Sample Solution

Electrolyte: tetra-n-butylammonium perchlorate (0.1 mol)

Specimen: acceptor compound (0.001 mol)

Solvent: dichloromethane (1 L)

As is described in the above item 3, the solubility of the organic acceptor in the solvent in a coating solution for photosensitive layer is less than 10% by weight, particularly preferably. When the solubility is not less than 10% by weight, organic acceptor compound molecules associated with phthalocyanine molecules are liable to diffuse in the coating solution for photosensitive layer and the sensitizing effect of the photosensitive material is drastically lowered.

The electrophotosensitive material of the present invention may be an arbitrary photosensitive material, a single-layer photosensitive material containing an electric charge generating material and an electron charge transferring material in a single photosensitive layer, or a multi-layer photosensitive material comprising an electric charge generating layer and an electric charge transferring layer, which are mutually laminated, as far as it contains, as the electric charge material, a novel phthalocyanine crystal according to the present invention.

The constituent materials of the electrophotosensitive material of the present invention will be described in detail hereinafter.

<Electric Charge Generating Agent>

The electric charge generating material used in the electrophotosensitive material of the present invention may contain a phthalocyanine crystal which comprises associating with an organic acceptor compound whose reduction potential to a reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V. Said phthalocianine can be produced during a step of converting into a pigment. These electric charge generating materials can be used alone, or can be used in combination with the other electric charge generating material.

The phthalocyanine in the present invention, as described hereinbefore, is a metal-free phthalocyanine or a metal phthalocyanine represented by the general formula (1).

The metal phthalocyanine represented by the general formula (1) includes, for example, aluminum phthalocyanine, vanadium phthalocyanine, cadmium phthalocyanine, antimony phthalocyanine, chromium phthalocyanine, copper 4-phthalocyanine, germanium phthalocyanine, iron phthalocyanine, chloroaluminum phthalocyanine, oxotitanyl phthalocyanine (CGM-2), chloroindium phthalocyanine, chlorogallium phthalocyanine, and magnesium phthalocyanine. The phthalocyanine of the general formula (1) is usually referred to as “metalo-phthalocyanine”.The crystal form that can be used may be any of α, β, γ, δ, ε, σ, × and π forms.

As the other electric charge generating material which can be used in combination of the phthalocyanine crystal of the present invention, there can be used various electric charge generating materials used conventionally in the photosensitive layer.

Examples thereof include selenium, selenium-tellurium, amorphous silicon, polycyclic quinone pigment, pyrylium pigment, squarium pigment, phthalocyanine pigment, azo pigment, disazo pigment, anthanthrone pigment, indigo pigment, threne pigment, toluidine pigment, pyrazoline pigment, perylene pigment, and quinacridone pigment.

As the organic acceptor compound, for example, there can be used compounds wherein a reduction potential to a reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V and a solubility in a solvent in a coating solution for photosensitive layer is less than 10% by weight, as described above.

Particularly preferably organic acceptor compounds include specific quinone derivative, diphenoquinone derivative, naphthoquinone derivative, dinaphthoquinone derivative, and diimide naphthalenecarboxylate, as represented by the above general formulas (3), (4) and (5).

These organic acceptor compounds can be used alone, or can be used in combination with other organic acceptor compounds. Specific examples of the organic acceptor compound are shown below. The reduction potential value and solubility in tetrahydrofuran (THF) as the solvent in the coating solution for photosensitive layer were simultaneously shown.

(AC-1) Reduction Potential: −0.95 V

Solubility: 3% by weight (THF)

(AC-2) Reduction Potential: −0.85 V

Solubility: 3% by weight (THF)

(AC-3) Reduction Potential: −0.85 V

Solubility: 1% by weight (THF)

(AC-4) Reduction Potential: −1.28 V

Solubility: 3% by weight (THF)

The phthalocyanine crystal of the present invention can be produced by a method descried in the above item (9) or (10). The phthalocyanine crystal of the above item (10) is characterized in that it is produced by adding the organic acceptor compound during the step of converting into a pigment.

The step of converting into a pigment refers to a step of dissolving phthalocyanine and an organic acceptor compound in a solvent (e.g. trihaloacetic acid such as trifluoroacetic acid or trichloroacetic acid, a mixed solvent of trihaloacetic acid/dichloromethane, and sulfuric acid) in which both of the phthalocyanine and organic acceptor compound dissolve at a temperature of 20 to 50° C., and adding dropwise the solution in a mixed solvent of water/methanol, thereby to deposit a crystal.

Then, the resulting crystal is washed with a solvent (e.g. methanol, etc.) having affinity with the dissolving solvent, washed with a large amount of a neutral solvent (e.g. water, etc.) to finally remove impurities (e.g. acid, alkali, etc.) until the filtrate becomes neutral, and then subjected to a dry or wet crystal converting step to convert into a desired crystal, which is sufficiently dried by vacuum drying.

The added amount of the organic acceptor compound is preferably not less than 0.5% by weight, and preferably not more than 100% by weight, based on the weight of phthalocyanine. When the amount of the organic acceptor is less than 0.5% by weight, the sensitizing effect is poor. On the other hand, when the amount is more than 100% by weight, the organic acceptor compound associated with a phthalocyanine molecule in the coating solution for photosensitive layer is liable to diffuse in the solvent, and a crystal made of only the organic acceptor compound is liable to be formed.

<Electric Charge Transferring Material>

As the electric charge transferring material used in the electrophotosensitive material of the present invention, there can be used various electric charge transferring materials which have conventionally been used in the photosensitive layer.

Examples of the electric charge transferring material include nitrogen-containing cyclic compounds as the hole transferring material, for example, oxadiazole compound such as 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole, styryl compound such as 9-4-(diethylaminostyryl)anthracene, carbazole compound such as polyvinylcarbazole, organic polysilane compound, pyrazoline compound such as 1-phenyl-3(p-dimethylaminophenyl)pyrazoline, hydazone compound, triphenylamine compound, indole compound, oxadiazole compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole compound, pyrazole compound, triazole compound, and stilbene compound; and electron transferring material, for example, pyrene compound, carbazole compound, hydrazone compound, N,N-dialkylaniline compound, diphenylamine compound, triphenylamine compound, naphthoquinone compound, pyrazoline compound, and styryl compound. These electric charge transferring materials can be used alone, or two or more kinds of them can be used in combination.

<Binder Resin>

As the binder resin used in the electrophotosensitive material of the present invention, for example, there can be used various resins which have conventionally been used in the photosensitive layer.

Examples of the binder resin include various polycarbonate resins having a bisphenol A skeleton or a bisphenol Z skeleton, polyacrylate, polyester resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide, polyurethane, polusulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, and polyether resin; crosslinkable thermosetting resins such as silicone resin, epoxy resin, phenol resin, urea resin, and melamine resin; and photocurable resins such as epoxy acrylate and urethane acrylate. These binder resins can be used alone, or two or more kinds of them can be used in combination.

Particularly preferred resin includes, for example, bisphenol Z type monomer and bisphenol Z type polycarbonate derived from phosgene, such as Panlight manufactured by Teijin Chemicals Co., Ltd. and PCZ manufactured by Mitsubishi Gas Chemicals Co., Ltd. The weight-average molecular weight of the binder resin is preferably within a range from 5,000 to 200,000, and more preferably from 15,000 to 100,000.

In case of the single-layer type, the film thickness of the photosensitive layer is preferably within a range from about 5 to 100 μm, and more preferably from about 10 to 50 μm. The electric charge generating material is preferably contained in the amount within a range from 0.1 to 50% by weight, and preferably from 0.5 to 30% by weight, based on the weight of the binder resin. The electron transferring material is preferably contained in the amount within a range from 20 to 500% by weight, and more preferably from 30 to 200%, based on the weight of the binder resin. In case of the single-layer type, the hole transferring material and electron transferring material are preferably used in combination as the electric charge transferring material.

In case where the photosensitive layer has a multi-layer structure, the film thickness of the electric charge generating layer preferably within a range from about 0.01 to 5 μm, and more preferably from about 0.1 to 3 g m. The film thickness of the electric charge transferring layer preferably within a range from about 2 to 100 μm, and more preferably from about 5 to 50 μm. The electric charge generating material is preferably contained in the electric charge generating layer in the amount within a range from 0.1 to 50% by weight, and preferably from 0.5 to 30% by weight, based on the weight of the whole binder resin. The electron transferring material is preferably contained in the electron transferring layer in the amount within a range from 20 to 500% by weight, and more preferably from 30 to 200%, based on the weight of the whole binder resin.

The single-layer type and multi-layer type photosensitive materials can be applied to any of positive charging type and negative charging type. It is particularly preferred that the single-layer type photosensitive material is used in the positive charging type, whereas, the multi-layer type photosensitive material is used in the negative charging type. When using the multi-layer type photosensitive material in the negative charging type, an electric charge generating layer and electric charge transferring layer are laminated from the substrate side in this sequence.

In addition to the above respective components, various conventionally known additives such as antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors (e.g. ultraviolet absorbers), softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, and donors can be incorporated into the photosensitive layer as far as these additives do not exert a deleterious influence on electrophotographic characteristics. To improve the sensitivity of the photosensitive layer, for example, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the electric charge generating material.

An undercoat layer may be formed between the substrate and photosensitive layer as far as it does not inhibit the characteristics of the photosensitive material. A protective (overcoat) layer may be formed on the surface of the photosensitive material.

As the substrate on which the photosensitive layer is formed, for example, various materials having the conductivity can be used. The substrate includes, for example, metallic simple substances such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass; plastic materials prepared by depositing or laminating the above metal; and glasses coated with aluminum iodide, tin oxide, and indium oxide.

The substrate may be in the form of a sheet or drum according to the structure of the image forming apparatus to be used. The substrate itself may have the conductivity, or the surface of the substrate may have the conductivity. The substrate may be preferably those having a sufficient mechanical strength on use.

When the photosensitive layer is formed by the coating method, a dispersion is prepared by dispersing and mixing the above electric charge generating material, electric charge transferring material and binder resin, together with a proper solvent, using a known method such as roll mill, ball mill, attritor, paint shaker, and ultrasonic dispersing equipment, and then the resulting dispersion is coated by using a known means and dried.

As the solvent for preparing the dispersion, various organic solvents can be used. The organic solvent includes, for example, alcohols such as methanol, ethanol, isopropanol, and butanol; aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, and cylohexanone; esters such as ethyl acetate and methyl acetate; and dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide. These solvents can be used alone, or two or more kinds of them can be used in combination.

To improve the dispersion properties of the electric charge generating material and electric charge transferring material, and the smoothness of the surface of the photosensitive layer, for example, various coupling agents, various surfactants, and various leveling agents such as silicone oil may be used.

EXAMPLES

The following Synthesis Examples, Synthesis Comparative Examples, Examples and Comparative Examples further illustrate the present invention in detail. The following embodiments are illustrative, and they should not be construed to limit the technical scope of the present invention.

Synthesis Example 1

Synthesis of Titanyl Phthalocyanine Crystal (CG-1)

In a flask wherein the atmosphere was replaced by argon, 1,3-diiminoisoindoline (25 g), titanium tetrabutoxide (CGM-2)(14.6 g) and diphenylmethane (300 g) were mixed and heated to 150° C. While vapor generated in the flask was distilled out of the reaction system, the temperature in the system was raised to 200° C. Then, the mixture was reacted by stirring for additional four hours.

After the completion of the reaction, the temperature in the system was cooled to 150° C., the reaction mixture was filtered through a glass filter. The resulting solid was washed twice with previously heated dimethylformamide (DMF), washed with DMF and methanol, and then vacuum-dried to obtain titanyl phthalocyanine (24 g).

Titanyl phthalocyanine (5 g) and AC-1 (0.2 g) as the organic acceptor compound were mixed and the mixture was dissolved in 100 ml of a mixed solution of dichloromethane/trifluoroacetic acid (volume ratio of 4:1). The resulting solution was added dropwise in 1 L of methanol/water (volume ratio: 1:1). After the completion of the dropwise addition, the reaction solution was stirred at room temperature for 15 minutes, allowed to stand for 30 minutes and then filtered through a glass filter. The resulting solid was washed with water until the filtrate becomes neutral, redispersed in 200 ml of chlorobenzene, and then filtered through a glass filter after stirring for one hour. The resulting solid was vacuum-dried at 50° C. for five hours to obtain 4.2 g of a titanyl phthalocyanine crystal (CG-1)of the present invention.

Synthesis Examples 2, 3 and 4

Synthesis of Titanyl Phthalocyanine Crystals (CG-2, CG-3 and CG-4)

In the same manner as in Synthesis Example 1, except that AC-2, AC-3 and AC-4 were used as the organic acceptor compound, titanyl phthalocyanine crystals (CG-2, CG-3 and CG-4) were obtained.

Synthesis Comparative Examples 1, 2, 3 and 4

Synthesis of Titanyl Phthalocyanine Crystals (CG-5, CG-6, CG-7 and CG-8)

In the same manner as in Synthesis Example 1, except that AC-5, AC-6, AC-7 and AC-8 were used as the organic acceptor compound, titanyl phthalocyanine crystals (CG-5, CG-6, CG-7 and CG-8) were obtained.

(AC-5) Reduction Potential: −1.53 V

Solubility: 5% by weight (THF)

(AC-6) Reduction Potential: −1.32 V

Solubility: 20% by weight (THF)

(AC-7) Reduction Potential: −0.37 V

Solubility: 3% by weight (THF)

(AC-8) Reduction Potential: −1.31 V

Solubility: 11% by weight (THF)

Synthesis Comparative Example 5

Synthesis of Titanyl Phthalocyanine Crystal (CG-9)

In the same manner as in Synthesis Example 1, except that no organic acceptor compound was used, a titanyl phthalocyanine crystal (CG-9) were obtained.

Examples 1 to 144

Single-layer Type Photosensitive Material

One kind (5 parts by weight) selected from the titanyl phthalocyanine crystals (CG-1 to CG-4) obtained in Synthesis Examples 1 to 4 as the electric charge generating material, one kind (70 parts by weight) selected from HT-1 to HT-15 as the hole transferring material, one kind (30 parts by weight) selected from ET-1 to ET-3 as the electron transferring material, a bis-Z type polycarbonate resin (100 parts by weight) having a weight-average molecular weight of 50,000 as the binder resin and tetrahydrofuran (800 parts by weight) were dispersed or dissolved using an ultrasonic dispersing apparatus to prepare a coating solution for single-layer type photosensitive layer. Then, an alumina tube as the substrate was coated with the coating solution according to a dip coating method, followed by hot-air drying at 110° C. for one hour to form a single-layer type photosensitive material having a photosensitive layer of 25 μm in a film thickness.

Comparative Examples 1 to 36

Single-layer Type Photosensitive Material

In the same manner as in Examples 1 to 144, except that the titanyl phthalocyanine crystal (CG-9) obtained in Synthesis Comparative Example 5 was used as the electric charge generating material, single-layer type photosensitive materials were produced.

Comparative Examples 37 to 40

Single-layer Type Photosensitive Material

In the same manner as in Examples 1 to 144, except that the titanyl phthalocyanine crystals (CG-5, CG-6, CG-7 and CG-8) obtained in Synthesis Comparative Examples 1, 2, 3 and 4 were used as the electric charge generating material, single-layer type photosensitive materials were produced.

Comparative Example 41

Single-layer Type Photosensitive Material

In the same manner as in Comparative Examples 1 to 36, except that 0.2 parts by weight of AC-1 as the organic acceptor compound was directly added (simple addition) in the coating solution for photosensitive layer, a single-layer type photosensitive material was produced.

Examples 145 to 205

Multi-layer Type Photosensitive Material

One kind (250 parts by weight) selected from the titanyl phthalocyanine crystals (CG-1 to CG-4) obtained in Synthesis Examples 1 to 4 as the electric charge generating material, polyvinyl butyral (100 parts by weight) having a weight-average molecular weight of 2,000 as the binder resin and tetrahydrofuran (1,500 parts by weight) were dispersed using an ultrasonic dispersing apparatus to prepare a coating solution for electric charge generating layer.

On the other hand, one kind (100 parts by weight) selected from HT-1 to HT-15 as the hole transferring material, a bis-Z type polycarbonate resin (100 parts by weight) having a weight-average molecular weight of 50,000 as the binder resin and toluene (1000 parts by weight) were dispersed using an ultrasonic dispersing apparatus to prepare a coating solution for electric charge transferring layer.

Then, an alumina tube as the substrate was coated with the coating solution according to a dipping method, followed by hot-air drying at 110° C. for 20 minutes to form an electric charge generating layer having a film thickness of 0.5 g in. Then, the electric charge generating layer was coated with the coating solution for electric charge transferring layer according to a dip coating method, followed by hot-air drying at 110° C. for 40 minutes to form a multi-layer type photosensitive material having a film thickness of 20 μm.

Comparative Examples 42 to 56

Multi-layer Type Photosensitive Material

In the same manner as in Examples 146 to 205, except that the titanyl phthalocyanine crystal (CG-9) obtained in Synthesis Comparative Example 5 was used as the electric charge generating material, multi-layer type photosensitive materials were produced.

Comparative Examples 57 to 60

Multi-layer Type Photosensitive Material

In the same manner as in Examples 145 to 205, except that the titanyl phthalocyanine crystals (CG-5, CG-6, CG-7 and CG-8) obtained in Synthesis Comparative Examples 1, 2, 3 and 4 were used as the electric charge generating material, multi-layer type photosensitive materials were produced.

Comparative Example 61

Multi-layer Type Photosensitive Material

In the same manner as in Comparative Examples 42 to 56, except that 10 parts by weight of AC-1 as the organic acceptor compound was directly added (simple addition) in the coating solution for electric charge generating layer, a coating solution for electric charge generating layer was produced. In the same manner as in Comparative Examples 42 to 56, except that the coating solution for electric charge generating layer was produced, a multi-layer type photosensitive material was produced.

The photosensitive materials of the respective Examples and Comparative Examples were subjected to the following test and their characteristics were evaluated.

Evaluation of Initial Sensitivity of Single-layer Type Photosensitive Material

Using a drum sensitivity tester (Model GENTEC SINCIA 30 M) manufactured by GENTEC Co., a voltage was applied on the surface of the photosensitive materials of the respective Examples and Comparative Examples to charge the surface at +700 V.

Then, the surface of each photosensitive material (exposure time: 80 msec.) was irradiated with monochromic light having a wavelength of 780 nm (half-width: 20 nm, light intensity: 15 μW/cm 2 ) from white light of a halogen lamp as an exposure light source through a band-pass filter, and then a surface potential at the time at which 330 msec. have passed since the beginning of exposure was measured as a potential after exposure V L (V). The smaller the potential after exposure, the higher the sensitivity of the photosensitive material.

Evaluation of Initial Sensitivity of Multi-layer Type Photosensitive Material

In the same manner as in case of the single-layer photosensitive material, except that the surface of the photosensitive material was charged at −700 V, the initial sensitivity was evaluated.

The results are shown in Tables 1 to 6 and FIGS. 1 to 4 .

	TABLE 1
								Vr
								calculated
	Electric							based on Vr
	charge		Reduction		Hole	Electron		(100) of
	generating	Organic	potential	Solubility/THF	transferring	transferrring		Comparative
	material	acceptor	[V]	[% by weight]	material	material	Vr [V]	Example
Single-layer	Example 1	CG-1	AC-1	−0.95	3	HT-1	ET-1	125	83
type	Example 2	CG-2	AC-2	−0.85	3	HT-1	ET-1	120	79
photosensitive	Example 3	CG-3	AC-3	−0.85	1	HT-1	ET-1	123	81
material	Example 4	CG-4	AC-4	−1.28	3	HT-1	ET-1	130	86
	Comp. Example 1	CG-9	No addition	—	—	HT-1	ET-1	151	100
	Example 5	CG-1	AC-1	−0.95	3	HT-4	ET-1	165	92
	Example 6	CG-2	AC-2	−0.85	3	HT-4	ET-1	158	88
	Example 7	CG-3	AC-3	−0.85	1	HT-4	ET-1	162	90
	Example 8	CG-4	AC-4	−1.28	3	HT-4	ET-1	168	93
	Comp. Example 2	CG-9	No addition	—	—	HT-4	ET-1	180	100
	Example 9	CG-1	AC-1	−0.95	3	HT-5	ET-1	168	94
	Example 10	CG-2	AC-2	−0.85	3	HT-5	ET-1	166	93
	Example 11	CG-3	AC-3	−0.85	1	HT-5	ET-1	168	94
	Example 12	CG-4	AC-4	−1.28	3	HT-5	ET-1	170	96
	Comp. Example 3	CG-9	No addition	—	—	HT-5	ET-1	178	100
	Example 13	CG-1	AC-1	−0.95	3	HT-6	ET-1	103	79
	Example 14	CC-2	AC-2	−0.85	3	HT-6	ET-1	99	76
	Example 15	CG-3	AC-3	−0.85	1	HT-6	ET-1	102	78
	Example 16	CG-4	AC-4	−1.28	3	HT-6	ET-1	109	84
	Comp. Example 4	CG-9	No addition	—	—	HT-6	ET-1	130	100
	Example 17	CG-1	AC-1	−0.95	3	HT-8	ET-1	162	94
	Example 18	CG-2	AC-2	−0.85	3	HT-8	ET-1	155	90
	Example 19	CG-3	AC-3	−0.85	1	HT-8	ET-1	158	92
	Example 20	CG-4	AC-4	−1.28	3	HT-8	ET-1	165	96
	Comp. Example 5	CG-9	No addition	—	—	HT-8	ET-1	172	100
	Example 21	CG-1	AC-1	−0.95	3	HT-9	ET-1	124	90
	Example 22	CG-2	AC-2	−0.85	3	HT-9	ET-1	117	85
	Example 23	CG-3	AC-3	−0.85	1	HT-9	ET-1	122	88
	Example 24	CG-4	AC-4	−1.28	3	HT-9	ET-1	130	94
	Comp. Example 6	CG-9	No addition	—	—	HT-9	ET-1	138	100
	Example 25	CG-1	AC-1	−0.95	3	HT-10	ET-1	174	96
	Example 26	CG-2	AC-2	−0.85	3	HT-10	ET-1	171	94
	Example 27	CG-3	AC-3	−0.85	1	HT-10	ET-1	173	95
	Example 28	CG-4	AC-4	−1.28	3	HT-10	ET-1	178	98
	Comp. Example 7	CG-9	No addition	—	—	HT-10	ET-1	182	100
	Example 29	CG-1	AC-1	−0.95	3	HT-11	ET-1	152	93
	Example 30	CG-2	AC-2	−0.85	3	HT-11	ET-1	150	92
	Example 31	CG-3	AC-3	−0.85	1	HT-11	ET-1	153	94
	Example 32	CG-4	AC-4	−1.28	3	HT-11	ET-1	158	97
	Comp. Example 8	CG-9	No addition	—	—	HT-11	ET-1	163	100
	Example 33	CG-1	AC-1	−0.95	3	HT-12	ET-1	143	91
	Example 34	CG-2	AC-2	−0.85	3	HT-12	ET-1	140	89
	Example 35	CG-3	AC-3	−0.85	1	HT-12	ET-1	141	90
	Example 36	CG-4	AC-4	−1.28	3	HT-12	ET-1	147	94
	Comp. Example 9	CG-9	No addition	—	—	HT-12	ET-1	157	100
	Example 37	CG-1	AC-1	−0.95	3	HT-13	ET-1	133	89
	Example 38	CG-2	AC-2	−0.85	3	HT-13	ET-1	131	87
	Example 39	CG-3	AC-3	−0.85	1	HT-13	ET-1	133	89
	Example 40	CG-4	AC-4	−1.28	3	HT-13	ET-1	139	93
	Comp. Example 10	CG-9	No addition	—	—	HT-13	ET-1	150	100
	Example 41	CG-1	AC-1	−0.95	3	HT-14	ET-1	135	92
	Example 42	CG-2	AC-2	−0.85	3	HT-14	ET-1	131	90
	Example 43	CG-3	AC-3	−0.85	1	HT-14	ET-1	133	91
	Example 44	CG-4	AC-4	−1.28	3	HT-14	ET-1	140	96
	Comp. Example 11	CG-9	No addition	—	—	HT-14	ET-1	146	100
	Example 45	CG-1	AC-1	−0.95	3	HT-15	ET-1	118	90
	Example 46	CG-2	AC-2	−0.85	3	HT-15	ET-1	114	87
	Example 47	CG-3	AC-3	−0.85	1	HT-15	ET-1	117	89
	Example 48	CG-4	AC-4	−1.28	3	HT-15	ET-1	123	94
	Comp. Example 12	CG-9	No addition	—	—	HT-15	ET-1	131	100

	TABLE 2
								Vr
								calculated
	Electric							based on Vr
	charge		Reduction		Hole	Electron		(100) of
	generating	Organic	potential	Solubility/THF	transferring	transferrring		Comparative
	material	acceptor	[V]	[% by weight]	material	material	Vr [V]	Example
Single-layer	Example 49	CG-1	AC-1	−0.95	3	HT-1	ET-1	117	91
type	Example 50	CG-2	AC-2	−0.85	3	HT-1	ET-2	114	89
photosensitive	Example 51	CG-3	AC-3	−0.85	1	HT-1	ET-2	116	91
material	Example 52	CG-4	AC-4	−1.28	3	HT-1	ET-2	123	96
	Comp. Example 13	CG-9	No addition	—	—	HT-1	ET-2	128	100
	Example 53	CG-1	AC-1	−0.95	3	HT-4	ET-2	160	94
	Example 54	CG-2	AC-2	−0.85	3	HT-4	ET-2	156	91
	Example 55	CG-3	AC-3	−0.85	1	HT-4	ET-2	160	94
	Example 56	CG-4	AC-4	−1.28	3	HT-4	ET-2	168	98
	Comp. Example 14	CG-9	No addition	—	—	HT-4	ET-2	171	100
	Example 57	CG-1	AC-1	−0.95	3	HT-5	ET-2	164	94
	Example 58	CG-2	AC-2	−0.85	3	HT-5	ET-2	161	92
	Example 59	CG-3	AC-3	−0.85	1	HT-5	ET-2	166	95
	Example 60	CG-4	AC-4	−1.28	3	HT-5	ET-2	172	98
	Comp. Example 15	CG-9	No addition	—	—	HT-5	ET-2	175	100
	Example 61	CG-1	AC-1	−0.95	3	HT-6	ET-2	95	78
	Example 62	CG-2	AC-2	−0.85	3	HT-6	ET-2	92	75
	Example 63	CG-3	AC-3	−0.85	1	HT-6	ET-2	94	77
	Example 64	CG-4	AC-4	−1.28	3	HT-6	ET-2	100	82
	Comp. Example 16	CG-9	No addition	—	—	HT-6	ET-2	122	100
	Example 65	CG-1	AC-1	−0.95	3	HT-8	ET-2	160	94
	Example 66	CG-2	AC-2	−0.85	3	HT-8	ET-2	154	91
	Example 67	CG-3	AC-3	−0.85	1	HT-8	ET-2	159	94
	Ecample 68	CG-4	AC-4	−1.28	3	HT-8	ET-2	165	97
	Comp. Example 17	CG-9	No addition	—	—	HT-8	ET-2	170	100
	Example 69	CG-1	AC-1	−0.95	3	HT-9	ET-2	115	88
	Example 70	CG-2	AC-2	−0.85	3	HT-9	ET-2	112	86
	Example 71	CG-3	AC-3	−0.85	1	HT-9	ET-2	114	88
	Example 72	CG-4	AC-4	−1.28	3	HT-9	ET-2	122	94
	Comp. Example 18	CG-9	No addition	—	—	HT-9	ET-2	130	100
	Example 73	CG-1	AC-1	−0.95	3	HT-10	ET-2	170	93
	Example 74	CG-2	AC-2	−0.85	3	HT-10	ET-2	168	92
	Example 75	CG-3	AC-3	−0.85	1	HT-10	ET-2	171	94
	Example 76	CG-4	AC-4	−1.28	3	HT-10	ET-2	175	96
	Comp. Example 19	CG-9	No addition	—	—	HT-10	ET-2	182	100
	Example 77	CG-1	AC-1	−0.95	3	HT-11	ET-2	147	92
	Example 78	CG-2	AC-2	−0.85	3	HT-11	ET-2	144	90
	Example 79	CG-3	AC-3	−0.85	1	HT-11	ET-2	146	91
	Example 80	CG-4	AC-4	−1.28	3	HT-11	ET-2	150	94
	Comp. Example 20	CG-9	No addition	—	—	HT-11	ET-2	160	100
	Example 81	CG-1	AC-1	−0.95	3	HT-12	ET-2	140	90
	Example 82	CG-2	AC-2	−0.85	3	HT-12	ET-2	136	88
	Example 83	CG-3	AC-3	−0.85	1	HT-12	ET-2	140	90
	Example 84	CG-4	AC-4	−1.28	3	HT-12	ET-2	145	94
	Comp. Example 21	CG-9	No addition	—	—	HT-12	ET-2	155	100
	Example 85	CG-1	AC-1	−0.95	3	HT-13	ET-2	131	89
	Example 86	CG-2	AC-2	−0.85	3	HT-13	ET-2	128	87
	Example 87	CG-3	AC-3	−0.85	1	HT-13	ET-2	130	88
	Example 88	CG-4	AC-4	−1.28	3	HT-13	ET-2	136	93
	Comp. Example 22	CG-9	No addition	—	—	HT-13	ET-2	147	100
	Example 89	CG-1	AC-1	−0.95	3	HT-14	ET-2	133	92
	Example 90	CG-2	AC-2	−0.85	3	HT-14	ET-2	127	88
	Example 91	CG-3	AC-3	−0.85	1	HT-14	ET-2	130	90
	Example 92	CG-4	AC-4	−1.28	3	HT-14	ET-2	138	95
	Comp. Example 23	CG-9	No addition	—	—	HT-14	ET-2	145	100
	Example 93	CG-1	AC-1	−0.95	3	HT-15	ET-2	115	88
	Example 94	CG-2	AC-2	−0.85	3	HT-15	ET-2	111	85
	Example 95	CG-3	AC-3	−0.85	1	HT-15	ET-2	114	88
	Example 96	CG-4	AC-4	−1.28	3	HT-15	ET-2	121	93
	Comp. Example 24	CG-9	No addition	—	—	HT-15	ET-2	130	100

	TABLE 3
								Vr
								calculated
	Electric							based on Vr
	charge		Reduction		Hole	Electron		(100) of
	generating	Organic	potential	Solubility/THF	transferring	transferrring		Comparative
	material	acceptor	[V]	[% by weight]	material	material	Vr [V]	Example
Single-layer	Example 97	CG-1	AC-1	−0.95	3	HT-1	ET-3	136	89.5
type	Example 98	CG-2	AC-2	−0.85	3	HT-1	ET-3	133	87.5
photosensitive	Example 99	CG-3	AC-3	−0.85	1	HT-1	ET-3	135	88.8
material	Example 100	CG-4	AC-4	−1.28	3	HT-1	ET-3	141	92.8
	Comp. Example 25	CG-9	No addition	—	—	HT-1	ET-3	152	100.0
	Example 101	CG-1	AC-1	−0.95	3	HT-4	ET-3	180	95.7
	Example 102	CG-2	AC-2	−0.85	3	HT-4	ET-3	178	94.7
	Example 103	CG-3	AC-3	−0.85	1	HT-4	ET-3	179	95.2
	Example 104	CG-4	AC-4	−1.28	3	HT-4	ET-3	182	96.8
	Comp. Example 26	CG-9	No addition	—	—	HT-4	ET-3	188	100.0
	Example 105	CG-1	AC-1	−0.95	3	HT-5	ET-3	181	96.3
	Example 106	CG-2	AC-2	−0.85	3	HT-5	ET-3	178	94.7
	Example 107	CG-3	AC-3	−0.85	1	HT-5	ET-3	179	95.2
	Example 108	CG-4	AC-4	−1.28	3	HT-5	ET-3	183	97.3
	Comp. Example 27	CG-9	No addition	—	—	HT-5	ET-3	188	100.0
	Example 109	CG-1	AC-1	−0.95	3	HT-6	ET-3	115	82.1
	Example 110	CG-2	AC-2	−0.85	3	HT-6	ET-3	112	80.0
	Example 111	CG-3	AC-3	−0.85	1	HT-6	ET-3	115	82.1
	Example 112	CG-4	AC-4	−1.28	3	HT-6	ET-3	121	86.4
	Comp. Example 28	CG-9	No addition	—	—	HT-6	ET-3	140	100.0
	Example 113	CG-1	AC-1	−0.95	3	HT-8	ET-3	171	92.4
	Example 114	CG-2	AC-2	−0.85	3	HT-8	ET-3	167	90.3
	Example 115	CG-3	AC-3	−0.85	1	HT-8	ET-3	169	91.4
	Example 116	CG-4	AC-4	−1.28	3	HT-8	ET-3	173	93.5
	Comp. Example 29	CG-9	No addition	—	—	HT-8	ET-3	185	100.0
	Example 117	CG-1	AC-1	−0.95	3	HT-9	ET-3	135	88.2
	Example 118	CG-2	AC-2	−0.85	3	HT-9	ET-3	133	86.9
	Example 119	CG-3	AC-3	−0.85	1	HT-9	ET-3	134	87.6
	Example 120	CG-4	AC-4	−1.28	3	HT-9	ET-3	139	90.8
	Comp. Example 30	CG-9	No addition	—	—	HT-9	ET-3	153	100.0
	Example 121	CG-1	AC-1	−0.95	3	HT-10	ET-3	179	90.9
	Example 122	CG-2	AC-2	−0.85	3	HT-10	ET-3	175	88.8
	Example 123	CG-3	AC-3	−0.85	1	HT-10	ET-3	176	89.3
	Example 124	CG-4	AC-4	−1.28	3	HT-10	ET-3	182	92.4
	Comp. Example 31	CG-9	No addition	—	—	HT-10	ET-3	197	100.0
	Example 125	CG-1	AC-1	−0.95	3	HT-11	ET-3	166	89.7
	Example 126	CG-2	AC-2	−0.85	3	HT-11	ET-3	164	88.6
	Example 127	CG-3	AC-3	−0.85	1	HT-11	ET-3	165	89.2
	Example 128	CG-4	AC-4	−1.28	3	HT-11	ET-3	171	92.4
	Comp. Example 32	CG-9	No addition	—	—	HT-11	ET-3	185	100.0
	Example 129	CG-1	AC-1	−0.95	3	HT-12	ET-3	155	90.6
	Example 130	CG-2	AC-2	−0.85	3	HT-12	ET-3	152	88.9
	Example 131	CG-3	AC-3	−0.85	1	HT-12	ET-3	153	89.5
	Example 132	CG-4	AC-4	−1.28	3	HT-12	ET-3	159	93.0
	Comp. Example 33	CG-9	No addition	—	—	HT-12	ET-3	171	100.0
	Example 133	CG-1	AC-1	−0.95	3	HT-13	ET-3	144	88.9
	Example 134	CG-2	AC-2	−0.85	3	HT-13	ET-3	142	87.7
	Example 135	CG-3	AC-3	−0.85	1	HT-13	ET-3	142	87.7
	Example 136	CG-4	AC-4	−1.28	3	HT-13	ET-3	147	90.7
	Comp. Example 34	CG-9	No addition	—	—	HT-13	ET-3	162	100.0
	Example 137	CG-1	AC-1	−0.95	3	HT-14	ET-3	145	89.5
	Example 138	CG-2	AC-2	−0.85	3	HT-14	ET-3	140	86.4
	Example 139	CG-3	AC-3	−0.85	1	HT-14	ET-3	145	89.5
	Example 140	CG-4	AC-4	−1.28	3	HT-14	ET-3	151	93.2
	Comp. Example 35	CG-9	No addition	—	—	HT-14	ET-3	162	100.0
	Example 141	CG-1	AC-1	−0.95	3	HT-15	ET-3	129	90.2
	Example 142	CG-2	AC-2	−0.85	3	HT-15	ET-3	128	89.5
	Example 143	CG-3	AC-3	−0.85	1	HT-15	ET-3	130	90.9
	Example 144	CG-4	AC-4	−1.28	3	HT-15	ET-3	133	93.0
	Comp. Example 36	CG-9	No addition	—	—	HT-15	ET-3	143	100.0

	TABLE 4
	Electric
	charge				Hole	Electron
	generating	Organic	Redox	Solubility/THF	transferring	transferring
	material	acceptor	potential	[% by weight]	material	material	Vr [V]
Single-layer	Example 1	CG-1	AC-1	−0.95	3	HT-1	ET-1	125
type	Comp. Example 37	CG-5	AC-5	−1.53	5	HT-1	ET-1	160
photosensitive	Comp. Example 38	CG-6	AC-6	−1.32	20	HT-1	ET-1	158
material	Comp. Example 39	CG-7	AC-7	−0.37	3	HT-1	ET-1	210
	Comp. Example 40	CG-8	AC-8	−1.31	11	HT-1	ET-1	155
	Comp. Example 41	CG-9	AC-1	−0.95	3	HT-1	ET-1	145
In Comparative Example 41, AC-1 was simply added and a crystal was deposited on the surface of the photosensitive layer.

	TABLE 5
							Vr
							calculated
	Electric						based on Vr
	charge		Reduction		Hole		(100) of
	generating	Organic	potential	Solubility/THF	transferring		Comparative
	material	acceptor	[V]	[% by weight]	material	Vr [V]	Example
Multi-layer	Example 145	CG-1	AC-1	−0.95	3	HT-1	−128	85.3
type	Example 146	CG-2	AC-2	−0.85	3	HT-1	−120	80.0
photosensitive	Example 147	CG-3	AC-3	−0.85	1	HT-1	−122	81.3
material	Example 148	CG-4	AC-4	−1.28	3	HT-1	−135	90.0
	Comp. Example 42	CG-9	No addition	—	—	HT-1	−150	100.0
	Example 149	CG-1	AC-1	−0.95	3	HT-4	−108	80.0
	Example 150	CG-2	AC-2	−0.85	3	HT-4	−101	74.8
	Example 151	CG-3	AC-3	−0.85	1	HT-4	−110	81.5
	Example 152	CG-4	AC-4	−1.28	3	HT-4	−119	88.1
	Comp. Example 43	CG-9	No addition	—	—	HT-4	−135	100.0
	Example 153	CG-1	AC-1	−0.95	3	HT-5	−265	73.4
	Example 154	CG-2	AC-2	−0.85	3	HT-5	−250	69.3
	Example 155	CG-3	AC-3	−0.85	1	HT-5	−257	71.2
	Example 156	CG-4	AC-4	−1.28	3	HT-5	−267	74.0
	Comp. Example 44	CG-9	No addition	—	—	HT-5	−361	100.0
	Example 157	CG-1	AC-1	−0.95	3	HT-6	−113	88.3
	Example 158	CG-2	AC-2	−0.85	3	HT-6	−105	82.0
	Example 159	CG-3	AC-3	−0.85	1	HT-6	−111	86.7
	Example 160	CG-4	AC-4	−1.28	3	HT-6	−120	93.8
	Comp. Example 45	CG-9	No addition	—	—	HT-6	−128	100.0
	Example 161	CG-1	AC-1	−0.95	3	HT-8	−178	87.7
	Example 162	CG-2	AC-2	−0.85	3	HT-8	−170	83.7
	Example 163	CG-3	AC-3	−0.85	1	HT-8	−174	85.7
	Example 164	CG-4	AC-4	−1.28	3	HT-8	−195	96.1
	Comp. Example 46	CG-9	No addition	—	—	HT-8	−203	100.0
	Example 165	CG-1	AC-1	−0.95	3	HT-9	−85	84.2
	Example 166	CG-2	AC-2	−0.85	3	HT-9	−72	71.3
	Example 167	CG-3	AC-3	−0.85	1	HT-9	−82	81.2
	Example 168	CG-4	AC-4	−1.28	3	HT-9	−90	89.1
	Comp. Example 47	CG-9	No addition	—	—	HT-9	−101	100.0
	Example 169	CG-1	AC-1	−0.95	3	HT-10	−110	88.7
	Example 170	CG-2	AC-2	−0.85	3	HT-10	−105	84.7
	Example 171	CG-3	AC-3	−0.85	1	HT-10	−105	84.7
	Example 172	CG-4	AC-4	−1.28	3	HT-10	−115	92.7
	Comp. Example 48	CG-9	No addition	—	—	HT-10	−124	100.0
	Example 173	CG-1	AC-1	−0.95	3	HT-11	−120	91.6
	Example 174	CG-2	AC-2	−0.85	3	HT-11	−112	85.5
	Example 175	CG-3	AC-3	−0.85	1	HT-11	−119	90.8
	Example 176	CG-4	AC-4	−1.28	3	HT-11	−128	97.7
	Comp. Example 49	CG-9	No addition	—	—	HT-11	−131	100.0
	Example 177	CG-1	AC-1	−0.95	3	HT-12	−103	86.6
	Example 178	CG-2	AC-2	−0.85	3	HT-12	−95	79.8
	Example 179	CG-3	AC-3	−0.85	1	HT-12	−100	84.0
	Example 180	CG-4	AC-4	−1.28	3	HT-12	−111	93.3
	Comp. Example 50	CG-9	No addition	—	—	HT-12	−119	100.0
	Example 181	CG-1	AC-1	−0.95	3	HT-13	−138	89.0
	Example 182	CG-2	AC-2	−0.85	3	HT-13	−130	83.9
	Example 183	CG-3	AC-3	−0.85	1	HT-13	−132	85.2
	Example 184	CG-4	AC-4	−1.28	3	HT-13	−148	95.5
	Comp. Example 51	CG-9	No addition	—	—	HT-13	−155	100.0
	Example 185	CG-1	AC-1	−0.95	3	HT-14	−150	87.2
	Example 186	CG-2	AC-2	−0.85	3	HT-14	−140	81.4
	Example 187	CG-3	AC-3	−0.85	1	HT-14	−148	86.0
	Example 188	CG-4	AC-4	−1.28	3	HT-14	−165	95.9
	Comp. Example 52	CG-9	No addition	—	—	HT-14	−172	100.0
	Example 189	CG-1	AC-1	−0.95	3	HT-15	−150	87.2
	Example 190	CG-2	AC-2	−0.85	3	HT-15	−143	83.1
	Example 191	CG-3	AC-3	−0.85	1	HT-15	−143	83.1
	Example 192	CG-4	AC-4	−1.28	3	HT-15	−158	91.9
	Comp. Example 53	CG-9	No addition	—	—	HT-15	−172	100.0
	Example 193	CG-1	AC-1	−0.95	3	HT-13	−143	94.1
	Example 194	CG-2	AC-2	−0.85	3	HT-13	−135	88.8
	Example 195	CG-3	AC-3	−0.85	1	HT-13	−138	90.8
	Example 196	CG-4	AC-4	−1.28	3	HT-13	−149	98.0
	Comp. Example 54	CG-9	No addition	—	—	HT-13	−152	100.0
	Example 197	CG-1	AC-1	−0.95	3	HT-14	−138	86.3
	Example 198	CG-2	AC-2	−0.85	3	HT-14	−133	83.1
	Example 199	CG-3	AC-3	−0.85	1	HT-14	−134	83.8
	Example 200	CG-4	AC-4	−1.28	3	HT-14	−145	90.6
	Comp. Example 55	CG-9	No addition	—	—	HT-14	−160	100.0
	Example 201	CG-1	AC-1	−0.95	3	HT-15	−125	90.6
	Example 202	CG-2	AC-2	−0.85	3	HT-15	−120	87.0
	Example 203	CG-3	AC-3	−0.85	1	HT-15	−121	87.7
	Example 204	CG-4	AC-4	−1.28	3	HT-15	−131	94.9
	Comp. Example 56	CG-9	No addition	—	—	HT-15	−138	100.0

	TABLE 6
	Electric
	charge				Hole
	generating	Organic	Redox	Solubility/THF	transferring
	material	acceptor	potential	[% by weight]	material	Vr [V]
Multi-layer	Example 145	CG-1	AC-1	−0.95	3	HT-1	−128
type	Comp. Example 57	CG-5	AC-5	−1.53	5	HT-1	−160
photosensitive	Comp. Example 58	CG-6	AC-6	−1.32	20	HT-1	−157
material	Comp. Example 59	CG-7	AC-7	−0.37	3	HT-1	−220
	Comp. Example 60	CG-8	AC-8	−1.31	11	HT-1	−160
	Comp. Example 61	CG-9	AC-1	−0.95	3	HT-1	−149
In Comparative Example 61, AC-1 was simply added and poor dispersion of the electric charge generating material occurred.

As is apparent from the drawings and tables, a photosensitive material comprising, as the electric charge generating material, a phthalocyanine crystal produced by adding an organic acceptor compound, wherein a reduction potential to a reference electrode (Ag + /Ag) is not less than −1.5 V and not more than −0.5 V and a solubility of the organic acceptor compound in a solvent in a coating solution for photosensitive layer is less than 10% by weight, during a step of converting into a pigment exhibits higher sensitivity than that of the photosensitive material containing a phthalocyanine crystal produced by adding no organic acceptor compound in both cases of the single-layer photosensitive material and multi-layer photosensitive material.

When the organic acceptor compound is simply adding in the coating solution for photosensitive layer or the coating solution for electric charge generating layer, crystallization of the photosensitive layer and poor dispersion of the electric charge generating material are liable to occur and, furthermore, the sensitivity also became poor (Comparative Example 41 in Table 4 and Comparative Example 61 in Table 6).

The disclosure of Japanese Patent Application Serial No.11-213814, filed on Jul. 28, 1999, is incorporated herein by reference.

Claims

1. A phthalocyanine crystal in which an organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V is associated with a phthalocyanine molecule wherein said organic acceptor compound contains a compound selected from a group represented by the following general formulas: wherein R1, R2, R3 and R4 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R1 and R2, or R3 and R4 may be combined with each other to form a ring; wherein R5, R6, R7, R8, R9, R10, R11, and R12 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R5 and R7, R6 and R8, R9 and R10, or R11 and R12 may be combined with each other to form a ring; and A1 represents a saturated or unsaturated alkyl group which may have a substituent, an aryl group, or a heterocycle which may have a substituent; wherein X1, X2, X3 and X4 are the same or different and each represents an oxygen atom or C(CN)2; R13 and R14 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent; and Y1 and Y2 are the same or different and each represents a carbon atom, an oxygen atom, or a nitrogen atom; and wherein X5 and X6 are the same or different and each represents an oxygen atom or C(CN)2; and R16, R17, and R18 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R16 and R17 may be combined with each other to form a ring.

2. The phthalocyanine crystal according to claim 1, wherein said phthalocyanine is a metal-free phthalocyanine.

3. The phthalocyanine crystal according to claim 1, wherein said phthalocyanine is a metal phthalocyanine represented by the general formula: wherein M is a metal of the groups IIa, IIIa, IVa, Va VII, Ib, IIb, IIIb, IVb or VIb on the periodic table or a group containing the metal.

4. The phthalocyanine crystal according to claim 3, wherein the group containing the metal is in the form of oxide, hydroxide, halide or cyanide.

5. The phthalocyanine crystal according to claim 3, wherein M is TiO.

6. The phthalocyanine crystal according to claim 1, wherein a solubility of said organic acceptor compound in a solvent in a coating solution for photosensitive layer is less than 10% by weight, said solvent is one or more member selected from the group consisting of alcohols, ketones, and ethers.

7. The phthalocyanine crystal according to claim 1 in which an organic acceptor compound is associated with a phthalocyanine molecule, which is produced by adding the organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V during a step of converting into a pigment.

8. An electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the photosensitive layer contains the phthalocyanine crystal of claim 7 as an electric charge generating material.

9. The electrophotosensitive material according to claim 8, which is a single-layer photosensitive material, comprising said phthalocyanine crystal and at least one of a hole transferring material and an electron transferring material dispersed into a binder resin.

10. The electrophotosensitive material according to claim 8, wherein said photosensitive layer is a laminated photosensitive layer which comprises an electric charge generating layer containing said phthalocyanine crystal and an electron transferring layer containing at least one of a hole transferring material and an electron transferring material.

11. A method of producing the phthalocyanine crystal of claim 1 in which an organic acceptor compound is associated with a phthalocyanine molecule, a step of which comprises: dissolving said phthalocyanine together with said organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5V in a solvent capable of dissolving both of said phthalocyanine and said organic acceptor compound, adding the resulting solution to an aqueous methanol, thereby crystallizing said phthalocyanine associated with said organic acceptor compound.

12. An electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the photosensitive layer contains the phthalocyanine crystal of claim 1 as an electric charge generating material.

13. The electrophotosensitive material according to claim 12, which is a single-layer photosensitive material comprising said phthalocyanine crystal and at least one of a hole transferring material and an electron transferring material dispersed into a binder resin.

14. The electrophotosensitive material according to claim 13, wherein said single photosensitive layer contains both of the hole transferring material and the electron transferring material.

15. The electrophotosensitive material according to claim 13, wherein said single photosensitive layer is formed by coating a coating solution which comprises adding said phthalocyanine crystal, at least one of the hole transferring material and the electron transferring material, and the binding resin to an organic solvent, and then drying the coated layer.

16. The electrophotosensitive material according to claim 13, wherein said binder resin containing a bisphenol z polycarbonate resin.

17. The electrophotosensitive material according to claim 12, wherein said photosensitive layer is a laminated photosensitive layer which comprises an electric charge generating layer containing said phthalocyanine crystal and an electron transferring layer containing at least one of a hole transferring material and an electron transferring material.

18. The electrophotosensitive material according to claim 17, wherein said electric charge generating layer is formed by coating a coating solution which comprises adding said phthalocyanine crystal and a binding resin to an organic solvent, and then drying the coated layer.

19. The electrophotosensitive material according to claim 17, wherein said photosensitive layer further comprises a binder resin contains a bisphenol z polycarbonate resin.

20. The phthalocyanine crystal according to claim 6, wherein the solvent is selected from the group consisting of methanol, ethanol, isopropanol, butanol, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, and cyclohexane.

21. A phthalocyanine crystal in which an organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V is associated with a phthalocyanine molecule, wherein said organic acceptor compound contains a compound represented by the general formula: wherein R1, R2, R3 and R4 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R1 and R2, or R3 and R4 may be combined with each other to form a ring.

22. A phthalocyanine crystal in which an organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V is associated with a phthalocyanine molecule wherein said organic acceptor compound contains a compound represented by the general formula: wherein R5, R6, R7, R8, R9, R10, R11, and R12 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R5 and R7, R6 and R8, R9 and R10, or R11 and R12 may be combined with each other to form a ring; and A1 represents a saturated or unsaturated alkyl group which may have a substituent, an aryl group, or a heterocycle which may have a substituent.

23. A phthalocyanine crystal in which an organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V is associated with a phthalocyanine molecule, wherein said organic acceptor compound contains a compound represented by the general formula: wherein X1, X2, X3 and X4 are the same or different and each represents an oxygen atom or C(CN)2; R13 and R14 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent; and Y1 and Y2 are the same or different and each represents a carbon atom, an oxygen atom, or a nitrogen atom.

24. A phthalocyanine crystal in which an organic acceptor compound whose reduction potential to a reference electrode (Ag+/Ag) is not less than −1.5 V and not more than −0.5 V is associated with a phthalocyanine molecule wherein said organic acceptor compound contains a compound represented by the general formula: wherein X5 and X6 are the same or different and each represents an oxygen atom or C(CN)2; and R16, R17, and R18 are the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl, alkyl halide, alkoxy, aryl, aralkyl, cycloalkyl, cyano, nitro or amino group which may have a substituent, with a proviso that R16 and R17 may be combined with each other to form a ring.