JP2002161217A - Metal oxide particle supporting organic pigment, method for producing the same, electrophotographic photoreceptor and pigment ink composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor having high abrasion resistance and excellent electric characteristics. SOLUTION: In this electrophotographic photoreceptor in which an under- coating layer 2, a charge generation layer 31, a charge transportation layer 32 and a protective layer 4 are laminated to an electroconductive substrate 1 in this order, a solution comprising metal oxide particles supporting titanyl phthalocyanine pigment as a charge generation material on the surface of titanium oxide particles is used as a coating solution of the protective layer. In this case, the coating solution of the protective layer is obtained by dissolving a polycarbonate and a fixed charge transportation substance in tetrahydrofuran with mixing to give a solution and by dispersing the organic pigment supporting titanium oxide particles into the solution. Consequently, the abrasion resistance of the photoreceptor is dramatically increased and electric characteristics are improved (residual potential is reduced).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to metal oxide particles carrying an organic pigment, a method for producing the same, and an electrophotographic photosensitive member and a pigment ink composition containing the same.

[0002]

2. Description of the Related Art It is disclosed in Japanese Patent Publication No. 63-18743 that the photoconductivity of titanium oxide can be spectrally sensitized with an organic pigment by combining titanium oxide and an organic pigment.
JP-A No. 2000-125 (photoreceptor in which titanium dioxide, a binder and a cyanine dye are dispersed). Further, it is described in JP-A-9-194774 and the like that an ink having excellent functions can be obtained by utilizing the coloring property of an organic pigment and the concealing property and coloring property of titanium oxide to white. I have.

[0003] In the above-mentioned combination of titanium oxide and organic pigment, these may be mixed and used, but it is often advantageous to make them in contact with each other so as not to separate them. For example, by bringing both into an adhesive state, it is possible to prevent titanium oxide having a higher specific gravity than the pigment from being separated and precipitated in the coating liquid for the photoreceptor or the recording liquid for the inkjet (pigment ink composition). In addition, it is possible to avoid a problem that the pigment and the titanium oxide are separated after the coating on the photoreceptor substrate or after the printing on the recording paper. Needless to say, in the case of a photosensitizing function that functions only when the pigment and the titanium oxide come into contact, the contact between the two is an essential condition.

[0004] Conventionally, there is no known accurate method for supporting a pigment on titanium oxide. A typical example of the related art is disclosed in Japanese Patent Publication No. 6-64353. In this method, titanium dioxide is treated with a mineral acid, and after washing with water, a cyanine dye is supported on titanium oxide.

This method has been possible because the cyanine dye is a dye and has high solubility in a solvent. However, this method is not adopted for pigments having low solubility in water or organic solvents. In both cases of the photoconductor coating liquid and the ink composition, a pigment having a smaller particle size is desired.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art.
A second object of the present invention is to provide metal oxide particles having an organic pigment carried on the surface of the metal oxide particles, and to provide a method for producing such metal oxide particles. Further, a third object of the present invention is to provide an electrophotographic photoreceptor having high abrasion resistance and good electrical characteristics by using such metal oxide particles in a photoreceptor coating solution.
Further, a fourth object is to provide a pigment ink composition having good dispersibility, which contains such metal oxide particles as an active ingredient.

[0007]

The metal oxide particles according to the present invention are characterized in that an organic pigment is carried on the surface of the metal oxide particles.

[0008] The metal oxide particles according to claim 2 are characterized in that an organic pigment is carried on an organic resin on the surface of the metal oxide particles.

According to a third aspect of the present invention, there is provided a metal oxide particle according to the first or second aspect, wherein the metal oxide particle is a titanium oxide particle. Depending on the purpose, tin oxide, aluminum oxide, indium oxide, zinc oxide and the like can be used as the metal oxide.

According to a fourth aspect of the present invention, in the metal oxide particles according to any one of the first to third aspects, the organic pigment has a charge generating function.

A metal oxide particle according to a fifth aspect is characterized in that, in any one of the first to fourth aspects, the organic pigment is phthalocyanine.

According to a sixth aspect of the present invention, in the method for producing metal oxide particles, the metal oxide particles are dispersed in a mineral acid solution of an organic pigment, and the dispersion is dropped into water to insolubilize the organic pigment. By doing so, the organic pigment is carried on the surface of the metal oxide particles.

According to a seventh aspect of the present invention, in the method for producing metal oxide particles, the metal oxide particles are dispersed in a mineral acid solution of an organic pigment, and the dispersion is dropped into water to insolubilize the organic pigment. The organic pigment is carried on the surface of the metal oxide particles, and the pigment-carrying metal oxide particles are immersed in a solution of an organic resin. It is characterized by being supported by resin.

The method for producing metal oxide particles according to claim 8 is characterized in that, in claim 6 or 7, the metal oxide particles are titanium oxide particles. Depending on the purpose, tin oxide, aluminum oxide, indium oxide, zinc oxide and the like can be used as the metal oxide.

In a ninth aspect of the present invention, there is provided the method for producing metal oxide particles, wherein the organic pigment has a charge generating function. Manufacturing method.

[0016] The method for producing metal oxide particles according to claim 10 is characterized in that, in any one of claims 6 to 9, the organic pigment is phthalocyanine.

An electrophotographic photoreceptor according to claim 11, wherein the protective layer is provided on the surface of the photoreceptor substrate, wherein the protective layer is provided on the surface of the photoreceptor substrate.
5. It is characterized by containing metal oxide particles carrying an organic pigment described in any one of 5.

[0018] The pigment ink composition according to claim 12 is
It is characterized by containing metal oxide particles carrying an organic pigment as described in any one of claims 1 to 5.

[0019]

An embodiment of the invention (electrophotographic photoreceptor) according to claim 11 will be described below with reference to the drawings. In the following, sulfuric acid is mentioned as a mineral acid in the method for producing metal oxide particles according to claim 6. In addition, titanium oxide particles are taken as metal oxide particles.

Generally, pigments have a large particle size, and particularly phthalocyanine pigments are large powders having a particle size of about 1 μm.
On the other hand, metal oxides such as titanium oxide also have a particle size of 0.05 to
It is a relatively large powder of 0.5 μm, and it is difficult to support the pigment on the surface of the titanium oxide as it is.

The present inventor has devised a method in which the pigment is applied to the surface of titanium oxide in sulfuric acid by utilizing the fact that the pigment is dissolved in sulfuric acid, and the titanium oxide is made insoluble by dropping it in water. Also, at that time, the crystalline pigment is usually once dissolved in sulfuric acid and dropped into water,
It was confirmed that an amorphous state having a very small particle size (a state without a clear X-ray diffraction peak) can be obtained.

The dissolving treatment of the pigment with sulfuric acid may be carried out in the same manner as a usual acid paste treatment. Sulfuric acid having a concentration of 70 to 100%, preferably 95 to 100% is used. Titanium oxide is added to the sulfuric acid solution of the pigment and stirred. The ratio of the pigment, titanium oxide and sulfuric acid is changed depending on the purpose. If the amount of titanium oxide is too small compared to sulfuric acid, the proportion of the pigment not supported on the surface of the titanium oxide particles increases. To prevent this, the sulfuric acid solution of the pigment is filtered, and only the titanium oxide remaining as a filtration residue and the pigment liquid adhering to the titanium oxide are taken out and dropped into water.

The degree of dropping into water and subsequent washing with water varies depending on the purpose, but when used as a material for an electrophotographic photosensitive member, washing is required until the sulfuric acid concentration becomes 500 ppm or less.

In order to further enhance the adhesion between the pigment and the titanium oxide, the surface of the titanium oxide particles is made of a resin (organic resin).
It is effective to cover with (claim 2). This is produced by immersing the organic pigment-carrying titanium oxide particles produced by the above-mentioned method in a resin solution, filtering and drying (claim 7). When a water-repellent organic compound such as polycarbonate is used as the supporting resin, an aromatic solvent such as toluene is used. On the other hand, when a polyamide-based solvent is used, an alcohol-based solvent is used. These resins are selected according to the purpose of use. Unless a resin capable of maintaining a state in which it is not dissolved in the coating liquid applied to the photoreceptor surface is used as the supporting resin, the organic pigment and the titanium oxide via the resin (indirectly) The effect of improving the adhesion cannot be obtained.

[0025] The metal oxide particles obtained by the method according to claim 6, wherein an organic pigment is carried on the surface of the metal oxide particles (claim 1), and the material obtained by the method according to claim 7 There are various possible uses of metal oxide particles in which an organic pigment is carried on an organic resin on the surface of the metal oxide particles (claim 2). The case of use will be described.

In general, electrophotographic photosensitive members have various problems such as wear of the photosensitive member due to repeated use, reduction in chargeability, increase in residual potential, and deterioration in image characteristics. Among them, it is particularly important that the surface of the photoreceptor wears out due to actual use. The pigment-carrying titanium oxide according to the present invention (claims 1 and 2) can be applied as an antiwear agent for the surface of a photoreceptor. In general, when titanium oxide is contained in the protective layer to improve wear resistance, a residual potential which is considered to be caused by titanium oxide is generated, which causes an abnormal image. On the other hand, by using the pigment-carrying titanium oxide particles according to the present invention, the residual potential can be reduced.

Hereinafter, the electrophotographic photosensitive member of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a laminated structure of an electrophotographic photoreceptor. An undercoat layer 2, a charge generation material (charge generation material) and a charge transport material (charge transport material) are provided on a conductive support 1. A single-layer photosensitive layer 3 serving as a main component and a protective layer (surface protective layer) 4 are laminated in this order. However, the undercoat layer 2 is not always necessary.

FIG. 2 is a cross-sectional view showing another example of the laminated structure of the electrophotographic photosensitive member. An undercoat layer 2, a charge generation layer 31, a charge transport layer 32, and a protective layer (surface protection) are formed on a conductive support 1. layer)
4 are laminated in this order. The charge generation layer 31 is mainly composed of a charge generation material as a photosensitive layer,
2 has a charge transport material as a main component.

FIG. 3 is a sectional view showing still another example of the laminated structure of the electrophotographic photosensitive member. In this photosensitive member, the stacking order of the charge generation layer 31 and the charge transport layer 32 is opposite to that of FIG. ). In the photoconductor of FIGS. 1 to 3, the protective layer 4 contains the pigment-carrying titanium oxide particles and, if necessary, a charge transport material. Note that these are merely examples, and other layer configurations may be adopted, or an appropriate intermediate layer or the like may be inserted and laminated.

The conductive support 1 has a volume resistance of 10 ¹⁰
Those exhibiting conductivity of Ω · cm or less, for example, (1) metals or alloys such as aluminum, nickel, chromium, copper, gold, silver, platinum, nichrome (nickel-chromium alloy), and metals such as tin oxide and indium oxide Film or cylindrical plastic or paper coated with oxide by vapor deposition or sputtering, (2) Aluminum, aluminum alloy, nickel, stainless steel, etc., or a plate made of such a material as extruded or drawn After forming into a tube, a surface-treated tube such as cutting, superfinishing, polishing, or the like can be used.

An endless nickel belt or an endless stainless belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can also be used as the conductive support 1. In addition, a material obtained by dispersing a conductive powder in a suitable binder resin on the support and coating the same can also be used as the conductive support 1. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, and metal oxide powder such as conductive tin oxide and ITO. Can be

The binder resin used simultaneously with the conductive powder includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, and polyvinyl chloride. , Vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin,
Thermoplastic, thermosetting resins such as ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin or light Curable resin is mentioned.

Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in a suitable solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, or the like, and applying the dispersion.

Further, a heat-shrinkable tube made of a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, or Teflon (registered trademark) containing the above-mentioned conductive powder is suitably used. A substrate coated on a cylindrical substrate and the layer of the heat-shrinkable tube is used as a conductive layer can also be favorably used as the conductive support 1.

Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a stacked layer. For convenience of explanation, first of all, the charge generation layer 31 will be described with reference to FIG. Can be used. Representative examples thereof include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, quinone condensed polycyclic compounds,
Squaric acid dyes, various phthalocyanine pigments,
Examples include naphthalocyanine pigments and azurenium salt dyes.

The charge generation layer 31 is formed by dispersing a charge generation material together with a binder resin (binder resin) in an appropriate solvent using a ball mill, an attritor, a sand mill, ultrasonic waves, or the like, if necessary. It is formed by coating on a support and drying.

The binder resin used for the charge generation layer 31 as required includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, Poly-N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl And pyrrolidone.
Above all, polyvinyl acetal represented by polyvinyl butyral is preferably used. The amount of the binder resin is suitably from 0 to 500 parts by weight, more preferably from 10 to 300 parts by weight, based on 100 parts by weight of the charge generating substance.

Examples of the solvent include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. Particularly, ketone solvents, ester solvents and ether solvents are preferably used. As a method of applying the coating solution, a method such as a dip coating method, a spray coat, a bead coat, a nozzle coat, a spinner coat, and a ring coat can be used.

The thickness of the charge generation layer 31 is 0.01 to 5 μm.
m is appropriate, and more preferably 0.1 to 2 μm. The charge transport layer 32 can be formed by dissolving or dispersing a charge transport substance and a binder resin in a suitable solvent, applying the solution on the charge generation layer, and drying. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

The charge transport material includes a hole transport material and an electron transport material. Examples of the charge transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives,
α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
-Styryl anthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc., and other known materials. These charge transport materials are used alone or in combination of two or more.

Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polystyrene. Vinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, Urethane resin,
Thermoplastic or thermosetting resins such as phenolic resins and alkyd resins are exemplified.

The amount of the charge transporting substance is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, per 100 parts by weight of the binder resin.
Parts by weight are appropriate. The thickness of the charge transport layer is 5 to 1
It is preferable that the thickness be about 00 μm. Examples of the solvent include tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, and acetone. For the charge transport layer, a polymer charge transport material having both a function as a charge transport material and a function as a binder resin is preferably used.

In the photoconductor of the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 32. As the plasticizer, those used as general plasticizers for resins, such as dibutyl phthalate and dioctyl phthalate, can be used as they are.
A suitable amount is about weight%. As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain are used. % By weight is appropriate.

Next, the structure of the single-layer photosensitive layer 3 will be described. The single-layer photosensitive layer can be formed by dissolving or dispersing the charge generating substance and the binder resin in an appropriate solvent, and applying and drying this. The photosensitive layer may be of a function-separated type to which the above-described charge transport material is added, and can be used favorably. Further, if necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

As the binder resin, the binder resins described in the description of the charge transport layer 32 can be used, and the binder resins described in the description of the charge generation layer 31 are mixed with these resins. It can also be used. Of course, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 5 to 40 parts by weight, and the amount of the charge transporting substance is 0 to 1 part by weight based on 100 parts by weight of the binder resin.
It is preferably 90 parts by weight, more preferably 50 to 150 parts by weight. The single-layer photosensitive layer is formed by dip coating or spraying a coating liquid obtained by dispersing a charge generating substance and a binder resin together with a charge transporting substance, if necessary, using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane using a dispersing machine. It can be formed by coating with a coat, a bead coat, or the like. The thickness of the single-layer photosensitive layer is 5 to 100 μm
The degree is appropriate.

In the photoreceptor of the present invention, an undercoat layer 2 can be provided between the conductive support 1 and the photosensitive layer, if necessary. The undercoat layer generally contains a resin as a main component. However, considering that a photosensitive layer is coated thereon with a solvent, this resin may be a resin having high solvent resistance to a general organic solvent. desirable. Such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymerized nylon, alcohol-soluble resins such as methoxymethylated nylon, polyurethane,
Curable resins that form a three-dimensional network structure, such as melamine resins, phenol resins, alkyd-melamine resins, epoxy resins, and the like. Further, a fine powder pigment of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moiré and reduce residual potential.

These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, the undercoat layer of the present invention includes Al
₂ O ₃ provided by anodic oxidation, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂
An inorganic material such as ₂ , ITO, CeO ₂ or the like provided by a vacuum thin film manufacturing method can also be used favorably. In addition, known materials can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

Next, the organic pigment-carrying titanium oxide-containing protective layer of the present invention will be described. As the resin used for the protective layer, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, poly Resin such as vinylidene chloride and epoxy resin. Among them, polycarbonate, particularly those having low gas permeability are preferable.

As the charge generation material of the organic pigment-carrying metal oxide used in the protective layer, basically any material having a function of generating charges by light irradiation may be used. Any material generally known as a charge generation material for a photosensitive layer can be used. Examples of the metal oxide include titanium oxide, tin oxide, and silicon oxide.
In addition, to make it easier for the protective layer to transfer charges,
A charge transport material may be included. This charge transporting material may be of the same type as that used for the single-layer photosensitive layer 3, or may be of a different type.

As a method for forming the protective layer, a usual coating method is employed. In particular, a spray coating method and a ring coating method are effective because they do not affect the lower layer. The thickness of the protective layer is suitably about 0.1 to 10 μm. The content of the organic pigment-supported metal oxide particles in the protective layer is suitably from 0.01 to 50% by weight, and more preferably from 0.1 to 10% by weight. If the content is too small, the effect of preventing residual potential is lost. On the other hand, if the amount is too large, light absorption increases, and light does not reach the lower charge generation layer. Of course, the light absorption wavelength of the charge generation material in the charge generation layer is different from that of the charge generation material in the protection layer. In the case of the method of irradiating the charge generating material of the above with light to remove the residual charge in the protective layer, light may not reach the charge generating material in the charge generating layer due to light absorption of the charge generating material in the protective layer. can avoid. When a charge transport material is contained, its amount is from 0 to 50% by weight.

In the photosensitive member of the present invention, an intermediate layer can be provided between the photosensitive layer and the protective layer. When the intermediate layer is formed, a binder resin is generally used as a main component. Examples of the binder resin include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. The thickness of the intermediate layer is 0.05 to 2 μm.
About m is appropriate.

[0053]

The present invention will be described below with reference to examples.
The present invention is not limited by the embodiments. All “parts” are by weight, and all “%” are by weight.

Example 1 An undercoat layer coating solution, a charge generation layer coating solution, a charge transport layer coating solution and a protective layer solution having the following compositions were sequentially coated and dried on an aluminum plate (conductive support). Fig. 2
Was produced. [Undercoat layer coating liquid] Titanium dioxide powder 500 parts Alkyd resin liquid 80 parts (solid content 60%) Melamine resin liquid 150 parts (solid content 50%) 2-butanone 500 parts After applying a coating on the surface of the substrate, drying was performed at 130 ° C. for 20 minutes. The thickness of the undercoat layer was about 3.5 μm. Titanium dioxide powder in the undercoat layer coating solution has the effect of adjusting the electric resistance of the undercoat layer and reducing the residual potential caused by the undercoat layer,
It is added for the effect of increasing the light scattering property to prevent moire images, and has a different purpose from the pigment-supported titanium oxide of the present invention.

[Coating solution for charge generation layer] Titanyl phthalocyanine pigment 1.5 parts Polyvinyl butyral resin 1 part 2-butanone 200 parts After coating the above-mentioned undercoat layer with a milling dispersion liquid having this formulation, drying was carried out at 60 ° C. For 20 minutes.
The thickness of the charge generation layer was about 0.2 to 0.5 μm.

[Coating solution for charge transport layer] 10 parts of polycarbonate Z 8 parts of charge transport material H-1 (Chemical Formula 1) 80 parts of tetrahydrofuran 80 parts of silicone oil 0.002 part After coating, the coating was dried at 120 ° C. for 20 minutes. The thickness of the charge transport layer was about 15 μm. The chemical structure of the charge transport material H-1 is shown by the following [Chemical Formula 1].

[0057]

Embedded image

[Protective Layer Coating Solution] In this example, the protective layer contains a charge generating material in the form of a metal oxide carrying the charge generating material. (1) [Production Example 1 of Titanium Oxide Carrying Charge Generating Material] 7.5 parts of 96% sulfuric acid was placed in a glass container, and 0.07 part of titanyl phthalocyanine pigment was added thereto and stirred and dissolved. . 2.3 parts of titanium oxide powder (trade name: TTO55 (N) manufactured by Ishihara Sangyo Co., Ltd.) was added thereto, and
The mixture was stirred and dispersed for minutes. This was gradually dropped into 200 parts of ion-exchanged water to precipitate and was filtered. This was further dispersed in 200 parts of ion-exchanged water, washed, and filtered. This operation is 1
Repeated 0 times. Finally, after washing with 100 parts of methanol, vacuum drying was performed at 75 ° C. to obtain titanium oxide particles carrying a pigment (yield: about 70%).

(2) [Preparation of Coating Solution for Protective Layer] 14 parts of tetrahydrofuran and polycarbonate Z
A solution was prepared by mixing and dissolving 0.47 part and 0.33 part of the charge transport material (H-1) whose chemical structure is represented by the above [Chemical Formula 1]. To this solution, 0.2 parts of titanium oxide particles supporting the above-mentioned charge generating material was added, and dispersed with 2 mm zirconia balls. This dispersion was used as a coating liquid for a protective layer.

Next, a protective layer coating solution having the above composition was coated on the charge transport layer and dried at 120 ° C. for 20 minutes to form a protective layer having a thickness of about 3 μm.

Example 2 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that titanium oxide particles carrying a charge generating material used in a protective layer coating solution were produced as follows. .

[Production Example 2 of Titanium Oxide Carrying Charge Generating Material] Polyamide having a concentration of 5% (trade name CM800)
0) Resin solution (solvent: methanol / butanol = 1/1)
(Volume ratio)) In 10 parts, 0.1% of the titanium oxide particles of Production Example 1 was added.
25 parts were added, and the mixture was stirred and dispersed at about 40 to 50 ° C for 30 minutes. This dispersion was filtered and dried to obtain metal oxide particles in which a titanyl phthalocyanine pigment was supported on titanium oxide particles with a polyamide resin.

Comparative Example 1 In Example 1, a simple titanium oxide was used in place of the titanium oxide supporting the charge generating material when preparing the coating liquid for the protective layer. This is an example in which the protective layer does not contain a charge generating material.

Next, Examples 1 and 2 thus obtained are described.
And the sensitivity of the laminated electrophotographic photosensitive member of Comparative Example 1 was examined.
This photoreceptor is used as an electrostatic copying paper tester (Kawaguchi Electric Co., Ltd.)
-6kV in a dark place using
After performing Rona discharge for 20 seconds and charging, another 20 seconds
After being left in a dark place, the surface potential V0 (V) was measured.
Then, 780 nm monochromatic light is applied to the photoreceptor surface at 5 μW / c.
m^Two And the potential from -800 volts
Exposure amount E until it becomes 1/2_1/2 (ΜJ / cm ^Two )
Issued. Further, the potential at 30 seconds after the exposure,
That is, the residual potential (V30 (V)) was measured. Further
In addition, the photoconductor maintains 0.29 μA /
cm^Two Adjust the amount of white light and the amount of charge so that the current flows
And continuously fatigue for 15 minutes.
Examined. The results are shown in Table 1 below.

[0065]

[Table 1]

From Table 1, it can be seen that by including the pigment-carrying metal oxide of the invention in the protective layer as in Examples 1 and 2, the potential (V3
0) decreases. It should be noted that the first and second embodiments were used.
In the above, the conductive support was a metal flat plate, but instead, a drum-shaped conductive support was used to produce an electrophotographic photoreceptor similarly (the charge generation layer and the charge transport layer were immersed in the photosensitive member). Although the coating and the protective layer were spray-coated, the same effect of reducing the residual potential as described above was obtained in this case as well, and when the residual potential was high, the image density did not decrease in the reversal development system. In contrast, in the formulation of Comparative Example 1, the concentration was reduced. Further, the wear resistance was dramatically improved due to the effect of titanium oxide in the protective layer.

Next, examples of application as a recording liquid (pigment ink composition) will be described. Example 3 [Production Example 3 of Titanium Oxide Carrying Pigment] In 7 parts of 96% sulfuric acid placed in a glass container, 0.5 part of titanyl phthalocyanine pigment was charged and dissolved by stirring. Add 1 part of titanium oxide powder (TTO, manufactured by Ishihara Sangyo Co., Ltd.)
55 (N)) and stirred and dispersed for 15 minutes. The dispersion was gradually dropped into 200 parts of ion-exchanged water, precipitated, and filtered. The obtained filtration residue was dispersed in 200 parts of ion-exchanged water, washed, and filtered. This operation was repeated 10 times. Lastly, after washing with 100 parts of methanol, vacuum drying was performed at 75 ° C. to obtain a titanium oxide powder carrying a pigment. Thereafter, the powder was converted to a 5% concentration polyamide (trade name CM8).
000) resin solution (solvent: methanol / butanol = 1)
/ 1 (volume ratio)) to about 50 to 50 ° C.
For 30 minutes. This dispersion was filtered and dried to obtain a titanium oxide powder in which titanyl phthalocyanine was supported on titanium oxide particles by a polyamide resin.

A mixture having the following composition was dispersed in a ball mill to prepare an ink. Ink composition Pigment-carrying titanium oxide particles 4 parts Acrylic resin 1 part Diethylene glycol 14 parts Glycerin 1 part Ion-exchanged water 80 parts For comparison, ordinary pigments were used instead of the pigment-carrying titanium oxide particles. When the pigment-supported titanium oxide particles were used, blue coloring on plain paper became clearer than in the comparative example. This is because the whiteness of titanium oxide effectively acts as a base.

[0069]

As apparent from the above description, the following effects can be obtained according to the present invention. (1) The invention according to Claims 1, 3, 4, and 5: An organic pigment on the surface of metal oxide particles having excellent properties and suitable for forming an electrophotographic photoreceptor or an ink composition for ink jet recording. Can be provided. According to the third aspect of the present invention, metal oxide particles particularly suitable for an electrophotographic photosensitive member can be provided.

(2) The surface of a metal oxide particle having excellent properties suitable for forming an electrophotographic photoreceptor or an ink composition for ink-jet recording. Metal oxide particles in which an organic pigment is carried by an organic resin. Claim 3
According to the invention, metal oxide particles particularly suitable for an electrophotographic photoreceptor can be provided.

(3) The invention according to claims 6, 8, 9 and 10 After the metal oxide particles are dispersed in a mineral acid solution of an organic pigment, the dispersion is dropped into water to insolubilize the organic pigment. Thereby, the metal oxide particles according to the first aspect of the present invention can be easily and accurately manufactured.

(4) The invention according to claims 7, 8, 9 and 10, wherein the metal oxide particles are dispersed in a mineral acid solution of an organic pigment,
This dispersion was dropped into water to insolubilize the organic pigment, thereby causing the organic pigment to be supported on the surface of the metal oxide particles,
The pigment-carrying metal oxide particles are immersed in an organic resin solution and then filtered, whereby the metal oxide particles according to the second aspect of the present invention can be easily and accurately manufactured.

(5) The invention of claim 11 In the electrophotographic photosensitive member having a photosensitive layer on the surface of the photosensitive member substrate and a protective layer covering the photosensitive layer, the protective layer is preferably defined by claim 1
Including the metal oxide particles carrying an organic pigment according to any one of the above (1) to (5), the wear resistance of the photoreceptor is greatly improved and the residual potential is reduced. Further, by using titanium oxide particles as metal oxide particles, the abrasion resistance is drastically improved.

(6) The invention according to the twelfth aspect is characterized by incorporating the metal oxide particles carrying an organic pigment according to any one of the first to fifth aspects, whereby a dispersibility useful for ink-jet recording and the like is obtained. And an ink composition having excellent image quality can be provided, whereby a high-quality image can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a laminated structure of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the laminated structure of the electrophotographic photosensitive member according to the present invention.

FIG. 3 is a cross-sectional view showing still another example of the laminated structure of the electrophotographic photosensitive member according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive support 2 Undercoat layer 3 Single layer photosensitive layer 4 Surface protective layer 31 Charge generation layer 32 Charge transport layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 5/147 503 G03G 5/147 503 F-term (Reference) 2H068 AA04 BA38 CA29 FA03 4J037 AA22 AA25 CB19 CC13 CC14 CC15 CC24 DD05 DD13 EE03 FF11 4J039 AB02 AD03 AD05 AD07 AD08 AD10 AE01 AE02 AE05 AE06 AE09 AE11 BA04 BA13 BA32 BA35 BA38 BC60 BD02 BE01 CA04 DA02 EA23 EA24 GA15

Claims (12)

[Claims] 1. A metal oxide particle comprising an organic pigment carried on the surface of the metal oxide particle. 2. A metal oxide particle comprising an organic pigment carried on the surface of the metal oxide particle by an organic resin. 3. The metal oxide particles according to claim 1, wherein the metal oxide particles are titanium oxide particles. 4. The metal oxide particles according to claim 1, wherein the organic pigment has a charge generation function. 5. The metal oxide particles according to claim 1, wherein the organic pigment is phthalocyanine. 6. After dispersing metal oxide particles in a mineral acid solution of an organic pigment, the dispersion is dropped into water to insolubilize the organic pigment. And a method for producing metal oxide particles. 7. The metal oxide particles are dispersed in a mineral acid solution of an organic pigment, and the dispersion is dropped into water to insolubilize the organic pigment, whereby the organic pigment is supported on the surface of the metal oxide particles. A metal oxide, wherein the pigment-carrying metal oxide particles are immersed in a solution of an organic resin, and then filtered, so that the organic pigment is carried on the surface of the metal oxide particles by the organic resin. Method for producing particles. 8. The method for producing metal oxide particles according to claim 6, wherein the metal oxide particles are titanium oxide particles. 9. The method for producing metal oxide particles according to claim 6, wherein the organic pigment has a charge generation function. 10. The method for producing metal oxide particles according to claim 6, wherein the organic pigment is phthalocyanine. 11. An electrophotographic photosensitive member having a photosensitive layer provided on a surface of a photosensitive member substrate and a protective layer covering the photosensitive layer,
An electrophotographic photosensitive member, wherein the protective layer contains metal oxide particles carrying an organic pigment according to any one of claims 1 to 5. 12. A pigment ink composition comprising the metal oxide particles carrying an organic pigment according to claim 1. Description: