JP5644562B2 - Method for producing organic photoreceptor - Google Patents

Description

  The present invention relates to a method for producing an organic photoreceptor used in an electrophotographic image forming apparatus.

  In general, a photoreceptor used in an electrophotographic image forming apparatus is repeatedly subjected to a series of image forming processes including a charging process, an exposure process, a developing process, a transfer process, a cleaning process, and a charge eliminating process. Accordingly, there is a demand for a photoreceptor that has little deterioration in electrical characteristics such as chargeability and potential retention even when the image forming process is repeated.

Conventionally, as a photoreceptor, for example, zinc oxide (ZnO), cadmium sulfide (CdS), cadmium selenide (CdSe), amorphous selenium-based (a-Se, a-Se-Te, a-As ₂ Se ₃ ), etc. However, in recent years, it has many advantages such as easy manufacturing, high sensitivity design, low cost, and no pollution. Therefore, an organic photoreceptor having an organic compound in the photosensitive layer has become the mainstream.

  Such an organic photoreceptor is generally soft because the surface layer is mainly composed of a low molecular charge transport material and an inert polymer, and when used repeatedly in an image forming process, it is mechanically subjected to a development process and a cleaning process. Wear easily due to excessive load. Such wear of the organic photoconductor causes a deterioration in electrical characteristics such as a deterioration in sensitivity and a decrease in chargeability, thereby causing a problem that a high-quality image cannot be formed over a long period of time.

In order to solve such a problem, a technique of providing a protective layer on the surface of an organic photoreceptor has been proposed (see, for example, Patent Document 1).
In general, such a protective layer is formed by coating a coating solution for forming a protective layer containing a polymerizable compound component on, for example, a photosensitive layer to form a coating film, and polymerizing the polymerizable compound component in the coating film. Although it is formed by curing, since the coating liquid for forming the protective layer has a low liquid viscosity, a coating film having an appropriate film thickness cannot be formed. As a result of not having a desired layer thickness, the protective layer is worn away by long-term use, and this causes a defective image due to a scratch on the surface of the protective layer, so that a high-quality image cannot be formed. There is. Further, since the coating liquid for forming the protective layer has a low liquid viscosity, coating unevenness occurs, and a protective layer having a uniform layer thickness cannot be formed. As a result, the image density decreases (image density unevenness). There is a problem that occurs.
Therefore, it is conceivable to increase the viscosity of the coating liquid for forming the protective layer to increase the thickness of the protective layer and solve the above problem.
Examples of the method for increasing the liquid viscosity of the protective layer forming coating solution include a method for increasing the solid content concentration in the coating solution, a method using a high viscosity solvent, and a method for adding a thickener.

However, in the method of increasing the solid content concentration in the coating liquid for forming the protective layer, the manufacturing cost increases, and when the metal oxide fine particles are added to the coating liquid, the metal oxide fine particles There is a problem that the dispersibility is lowered. Further, in the method using a high-viscosity solvent, there is a problem that the boiling point of the coating solution becomes high and the solvent remaining in the formed protective layer adversely affects the image quality. Furthermore, in the method of adding a thickener, there is a problem that the strength of the protective layer to be formed is lowered when the thickener is added to such an extent that an appropriate liquid viscosity is obtained.
In addition to the methods described above, a method of adding a polymer to the coating solution for forming the protective layer is conceivable. However, in such a method, since the polymer is mainly composed, the crosslinking density is lowered. Therefore, there is a problem that sufficient strength cannot be secured in the protective layer.

JP 2008-96528 A

  The present invention has been made based on the circumstances as described above, and the object thereof is to produce an organic photoreceptor in which the protective layer has a desired layer thickness while the protective layer has sufficient strength. It is to provide a method.

The organic photoreceptor production method of the present invention is a method for producing an organic photoreceptor in which an organic photoreceptor layer and a protective layer are laminated in this order on a conductive support,
Protective layer forming coating solution comprising a polymerizable compound component having a reactive group to form a cured resin constituting the protective layer, and a thickener component having a reactive group that undergoes a polymerization reaction with the polymerizable compound component It has a step of applying a,
The polymerizable compound component comprises a compound having an acryloyl group or a methacryloyl group as a reactive group,
The thickener component comprises a compound having an acryloyl group or a methacryloyl group as a reactive group,
The cured resin constituting the protective layer is formed by polymerizing a reactive group of the polymerizable compound component and a reactive group of the thickener component to cure. .

In the method of manufacturing an organic photoreceptor of the present invention, the thickener component having a reactive group, it is preferably made of a cellulose derivative having a reactive group.

  In the method for producing an organic photoreceptor of the present invention, it is preferable that the thickener component is contained in a proportion of 0.1 to 5% by mass in the protective layer forming coating solution.

  In the method for producing an organic photoreceptor of the present invention, it is preferable that the protective layer-forming coating solution contains metal oxide fine particles.

  In the method for producing an organophotoreceptor of the present invention, the metal oxide fine particles are preferably alumina fine particles or tin oxide fine particles surface-treated with a surface treatment agent having a reactive group.

  In the method for producing an organophotoreceptor of the present invention, the surface treatment agent preferably has an acryloyl group or a methacryloyl group as a reactive group.

  According to the method for producing an organophotoreceptor of the present invention, by having a step of applying a protective layer forming coating solution containing a polymerizable compound component and a thickener component that undergoes a polymerization reaction with the polymerizable compound component. When the protective layer-forming coating liquid having an appropriate liquid viscosity is applied to form a coating film having an appropriate film thickness, and when the polymerizable compound component in the coating film is cured by polymerization reaction, Since the thickener component itself is incorporated into the polymerization reaction system, an organic photoreceptor in which the protective layer has a desired layer thickness while the protective layer has sufficient strength can be obtained. Therefore, according to the method for producing an organic photoreceptor of the present invention, it is possible to increase the thickness of the protective layer while the protective layer has sufficient strength. Occurrence of image defects due to wear is suppressed, and an organic photoreceptor capable of forming a high-quality image is obtained. Moreover, since the coating liquid for forming the protective layer has an appropriate liquid viscosity, the occurrence of coating unevenness can be suppressed, and a protective layer having a uniform layer thickness can be formed. The occurrence of density unevenness can be suppressed.

It is sectional drawing for description which shows an example of a structure of the circular slide hopper coating device used for the protective layer formation process in the manufacturing method of the organic photoreceptor of this invention. It is a perspective sectional view of the circular slide hopper applicator shown in FIG.

  Hereinafter, the present invention will be described in detail.

  The method for producing an organic photoreceptor of the present invention is a method for producing an organic photosensitive layer and a protective layer laminated in this order on a conductive support, and a cured resin constituting the protective layer is formed. This is a method comprising a step of applying a protective layer-forming coating solution containing a power polymerizable compound component and a thickener that undergoes a polymerization reaction with the polymerizable compound.

The organic photoreceptor obtained by the production method of the present invention is not particularly limited as long as an organic photosensitive layer and a protective layer are laminated in this order on a conductive support, but specifically, the following (1 ) And (2).
(1) A layer structure in which a charge generation layer, a charge transport layer, and a protective layer are laminated in this order as an intermediate layer and an organic photosensitive layer on a conductive support.
(2) A layer structure in which an intermediate layer, a single layer containing a charge generation material and a charge transport material as an organic photosensitive layer, and a protective layer are laminated in this order on a conductive support.

  In the present invention, the organic photoreceptor means a structure in which at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoreceptor is exhibited by an organic compound. Includes all known organic photoreceptors such as a photoreceptor having a photosensitive layer composed of a generating material or an organic charge transport material, and a photoreceptor having a photosensitive layer in which a charge generating function and a charge transport function are composed of a polymer complex Say.

As a method for producing the organic photoreceptor of the present invention, the case of producing an organic photoreceptor having the layer structure (1) will be specifically described below.
Step (1): A step of forming an intermediate layer by applying and drying an intermediate layer-forming coating solution on the outer peripheral surface of the conductive support.
Step (2): a step of forming a charge generation layer by applying and drying a charge generation layer forming coating solution on the outer peripheral surface of the intermediate layer formed on the conductive support.
Step (3): A step of forming a charge transport layer by applying and drying a charge transport layer forming coating solution on the outer peripheral surface of the charge generation layer formed on the intermediate layer.
Step (4): A step of forming a protective layer by applying and drying a protective layer-forming coating solution on the outer peripheral surface of the charge transport layer formed on the charge generation layer.

[Step (1): Intermediate layer forming step]
In this step (1), for example, a binder resin is dissolved in a known solvent to prepare an intermediate layer forming coating solution, and this intermediate layer forming coating solution is applied to the outer peripheral surface of the conductive support. An intermediate layer can be formed by forming a film and drying the coating film.

  The intermediate layer formed in step (1) provides a barrier function and an adhesive function between the conductive support and the organic photosensitive layer. From the viewpoint of preventing various failures, it is preferable to provide such an intermediate layer.

(Conductive support)
The conductive support on which the intermediate layer is formed is not particularly limited as long as it has conductivity. For example, a metal such as aluminum, copper, chromium, nickel, zinc, and stainless steel is drum-shaped or Sheet shaped, laminated metal foil such as aluminum or copper on plastic film, deposited aluminum, indium oxide and tin oxide etc. on plastic film, or coated with conductive material alone or with binder resin Examples thereof include metals provided with a conductive layer, plastic films, and paper.

(Binder resin)
Examples of the binder resin used in the step (1) include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. The binder resin may be an alcohol-soluble polyamide resin. preferable.

(solvent)
As the solvent used in the step (1), those in which inorganic fine particles described later are well dispersed and the polyamide resin is dissolved are preferable. Specifically, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol are used. Alcohols having 2 to 4 carbon atoms such as t-butanol and sec-butanol are particularly preferred from the viewpoints of solubility and applicability of the polyamide resin.
In the step (1), in order to improve the storage stability and dispersibility of the inorganic fine particles, it is preferable to use a co-solvent together with a solvent. Examples of co-solvents that can be used in combination include methanol, benzyl alcohol, toluene, Examples include methylene chloride, cyclohexanone, and tetrahydrofuran.

(Inorganic fine particles)
The coating liquid for forming an intermediate layer may contain inorganic fine particles such as various conductive fine particles and metal oxide fine particles for the purpose of adjusting the resistance of the formed intermediate layer.

  Examples of the inorganic fine particles contained in the coating liquid for forming the intermediate layer include metal oxide fine particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide, and doped with tin. Ultrafine particles such as indium oxide, antimony-doped tin oxide and zirconium oxide can also be used. These metal oxide fine particles can be used singly or in combination of two or more. When two or more metal oxide fine particles are used in combination, the metal oxide fine particles are in a solid solution state. It may be in a fused state.

The number average primary particle size of such metal oxide fine particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.
In the present invention, the number average primary particle size of the metal oxide fine particles is measured as follows.
That is, a 10000 times magnified photograph was taken with a scanning electron microscope “JSM-7500F” (manufactured by JEOL Ltd.), and a photographic image (excluding aggregated particles) obtained by randomly capturing 300 metal oxide fine particles with a scanner. Calculation is performed using an automatic image processing analysis apparatus “LUZEX AP” (software version Ver. 1.32, manufactured by Nireco).

  The means for dispersing the inorganic fine particles in the intermediate layer forming coating solution is not particularly limited, and examples thereof include a dispersing machine such as an ultrasonic dispersing machine, a ball mill, a sand grinder, and a homomixer.

  The addition amount of the inorganic fine particles is preferably 20 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  Although it does not specifically limit as a coating method of the coating liquid for intermediate | middle layer formation, For example, the dip coating method, the spray coating method, etc. are mentioned.

  The method for drying the coating film of the coating solution for forming the intermediate layer can be appropriately selected according to the type of the solvent and the layer thickness of the intermediate layer to be formed, but a method by thermal drying is preferred.

  The layer thickness of the intermediate layer formed in the step (1) is preferably 0.1 to 15 μm, more preferably 0.3 to 10 μm.

[Step (2): Charge Generation Layer Formation Step]
In this step (2), for example, a charge generation material is added and dispersed in a binder resin dissolved in a known solvent to prepare a charge generation layer forming coating solution. The charge generation layer can be formed by coating the outer peripheral surface of the intermediate layer formed in the step (1) to form a coating film and drying the coating film.

(Binder resin)
As the binder resin used in the step (2), a known resin can be used. For example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, Epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and copolymer resin containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer) Resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin), poly-vinylcarbazole resin, and the like, but are not limited thereto.

(solvent)
Examples of the solvent used in the step (2) include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, Examples thereof include, but are not limited to, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine and the like.

(Charge generating material)
The charge generation material used in the step (2) is not particularly limited. For example, azo raw materials such as Sudan Red and Diane Blue; quinone pigments such as pyrenequinone and anthanthrone; quinocyanine pigments; perylene pigments; Indigo pigments such as thioindigo; phthalocyanine pigments and the like. These charge generation materials can be used alone or in combination of two or more.

  The amount of the charge generating material added is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin.

  The means for dispersing the charge generating material is not particularly limited, and examples thereof include a dispersing machine such as an ultrasonic dispersing machine, a ball mill, a sand grinder, and a homomixer.

  The method for applying the charge generation layer forming coating solution is not particularly limited, and examples thereof include a dip coating method and a spray coating method.

  The method for drying the coating film of the coating solution for forming the charge generation layer can be appropriately selected according to the type of the solvent and the layer thickness of the charge generation layer to be formed, but a method by thermal drying is preferred.

  The layer thickness of the charge generation layer formed in the step (2) varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, more preferably 0.00. It is 05-3 micrometers. It should be noted that the coating solution for forming the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating. The pigment can also be formed by vacuum deposition.

[Step (3): Charge Transport Layer Formation Step]
In this step (3), for example, a charge transport material (CTM) is added to a binder resin dissolved in a known solvent to prepare a charge generation layer forming coating solution. Is applied to the outer peripheral surface of the charge generation layer formed in step (2) to form a coating film, and the coating film is dried to form the charge transport layer.

(Binder resin)
As the binder resin used in the step (3), a known resin can be used, and polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, styrene. -A methacrylic acid ester copolymer resin etc. are mentioned, However, A polycarbonate resin is preferable. Furthermore, bisphenol A (BPA), bisphenol Z (BPZ), dimethyl BPA, BPA-dimethyl BPA copolymer and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

(solvent)
Examples of the solvent used in the step (3) include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4- Examples include, but are not limited to, dioxane, 1,3-dioxolane, pyridine, diethylamine and the like.

(Charge transport material)
Examples of the charge transport material used in the step (3) include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, Styryl compound, hydrazone compound, pyrazoline compound, oxazolone derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, triarylamine derivative, phenylenediamine derivative, stilbene derivative, benzidine derivative, poly-N -Vinylcarbazole, poly-1-vinylpyrene and poly-9-vinylanthracene, triphenylamine derivatives Etc., and the like. These charge transport materials can be used alone or in combination of two or more.

  The addition amount of the charge transport material is preferably 10 to 500 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

  The charge transport layer forming coating solution may contain an antioxidant, an electronic conductive agent, a stabilizer and the like as necessary. Examples of the antioxidant include those described in Japanese Patent Application No. 11-200135, and examples of the electronic conductive agent include those described in JP-A Nos. 50-137543 and 58-76483.

  The coating method of the charge transport layer forming coating solution is not particularly limited, and examples thereof include a dip coating method and a spray coating method.

  The method for drying the coating film of the coating liquid for forming the charge transport layer can be appropriately selected according to the type of the solvent and the layer thickness of the charge transport layer to be formed, but a method by thermal drying is preferred.

  The layer thickness of the charge transport layer formed in the step (3) varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, etc., but is preferably 5 to 40 μm, more preferably 10 to 30 μm. is there.

[Step (4): Protective layer forming step]
In this step (4), a polymerizable compound component that should form a cured resin constituting the protective layer, a thickener component that undergoes a polymerization reaction with the polymerizable compound component, a polymerization initiator, and, if necessary, metal oxidation The protective layer forming coating solution is prepared by adding the fine particles to a known solvent, and this protective layer forming coating solution is applied to the outer peripheral surface of the charge transport layer formed in the step (3) to form a coating film. Then, this coating film is dried, and a protective layer is formed by curing the polymerizable compound component and the thickener component in the coating film by irradiating active rays such as ultraviolet rays and electron beams. Can do.

(Polymerizable compound component)
Although it does not specifically limit as a polymeric compound component used in a process (4), For example, a styrene monomer, an acrylic monomer, a methacrylic monomer, a vinyl toluene monomer, a vinyl acetate monomer, an N-vinyl pyrrolidone monomer Etc. These polymerizable compound components can be used alone or in combination of two or more.

Since the polymerizable compound component can be cured in a small amount of light or in a short time, the polymerizable compound component is more than a compound having a reactive group of an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—). It is preferable to become.

  Specific examples of the compound having an acryloyl group or a methacryloyl group as the polymerizable compound component include those shown in the following exemplified compounds 1 to 44. Moreover, the number of groups shown below is the number of acryloyl groups or methacryloyl groups.

  In the exemplary compounds 1 to 44, R is an acryloyl group represented by the following formula (1), and R ′ is a methacryloyl group represented by the following formula (2).

The polymerizable compound component is more preferably composed of a compound having two or more acryloyl groups or methacryloyl groups, and particularly preferably composed of a compound having three or more acryloyl groups or methacryloyl groups.
Moreover, although 2 or more types of polymerizable compound components can be used in combination, in this case as well, it is preferable to use 50% by mass or more of a compound having three or more acryloyl groups or methacryloyl groups.

(Thickener component)
The thickener component used in the step (4) is not particularly limited as long as it is a compound having a reactive group that undergoes a polymerization reaction with the polymerizable compound component, but a cellulose derivative having a reactive group (hereinafter referred to as “reaction”). It is also preferred that it is also referred to as “a functional group-containing cellulose derivative”.
The thickener component is preferably composed of a compound having an acryloyl group or a methacryloyl group, and is particularly preferably composed of a cellulose derivative having an acryloyl group or a methacryloyl group.

As the reactive group-containing cellulose derivative, the following are preferably used as raw materials. That is, it is preferable to use one in which 0.5 to 2.5 R ¹ O— is substituted on three hydroxyl groups per glucose unit constituting cellulose (hereinafter also referred to as “raw cellulose derivative”). . Here, R ¹ represents a linear or branched alkyl group having 2 to 4 carbon atoms, and as such a group R ¹ , an ethyl group and a propyl group are preferable.
Specific examples of the raw material cellulose derivative include ethyl cellulose and propyl cellulose, and ethyl cellulose is particularly preferable.

  The reason why it is preferable to use the above-mentioned cellulose derivative substituted with an alkyl group as a raw material for the reactive group-containing cellulose derivative is that unsubstituted cellulose has a remarkably low solubility in water or various organic solvents. It is necessary to carry out the reaction in a state where cellulose is dispersed in a solvent. For this reason, the reactivity is remarkably inferior, and it becomes difficult to obtain cellulose substituted with a reactive group for a desired amount. This is because the hydroxyl group of glucose constituting cellulose in or between celluloses does not dissolve in water or various organic solvents by forming an association state through hydrogen bonds. In order to weaken this hydrogen bond, a part of the hydroxyl group in glucose may be substituted. Cellulose partially substituted with hydroxyl groups becomes soluble in water or various organic solvents, and the reactivity is sufficiently improved as compared with unsubstituted cellulose, so that a cellulose substituted with a reactive group is obtained in a desired amount. be able to.

The average degree of substitution of ethyl groups and propyl groups contained in the raw material cellulose derivative is preferably 0.5 to 2.5 per glucose unit, and more preferably 0.9 to 1.5 per glucose unit.
When the average substitution degree of ethyl group or propyl group contained in the raw material cellulose derivative is too low, the synthesis may be difficult due to poor solubility, while the ethyl group or propyl contained in the raw material cellulose derivative may be difficult. In the case where the average degree of substitution of the group is excessive, the number of substituted reactive groups to be substituted decreases, and a desired strength cannot be expressed when it is incorporated into a reaction system.

In the present invention, the average degree of substitution of ethyl groups and propyl groups means the average number of moles of ethoxy groups and propoxy groups per glucose unit constituting cellulose, and the calculation method is methoxyacetyl in a pyridine solvent. Methoxyacetylation of the unreacted hydroxyl group in the product obtained using chloride was carried out, and the ¹ H-NMR spectrum of the methoxyacetylated product was measured, and 3.2 to 4.6 ppm (in deuterated chloroform solvent, TMS standard). ) Observed from the integral ratio of the methyl proton and methylene proton signals derived from the methoxyacetyl group and the proton signal derived from the introduced alkyl group.
For the NMR measurement, “FT-NMR LA-400” (manufactured by JEOL Ltd.) is used.

In addition, the average substitution degree of the reactive group contained in the reactive group-containing cellulose derivative is preferably 0.5 to 2.5 per glucose unit, more preferably 0.9 to 1.5 per glucose unit. It is.
When the average substitution degree of the reactive group contained in the reactive group-containing cellulose derivative is too small, the protective layer formed may not have sufficient strength, while the reactive group In the case where the average substitution degree of the reactive group contained in the cellulose derivative is excessive, the synthesis is practically difficult.

In the present invention, the average degree of substitution of reactive groups means the average number of added moles of (meth) acryloyl groups per glucose unit constituting cellulose, and the calculation method is as follows. Methoxyacetylation of the unreacted hydroxyl group in the product obtained using chloride was carried out, and the ¹ H-NMR spectrum of the methoxyacetylated product was measured, and 3.2 to 4.6 ppm (in deuterated chloroform solvent, TMS standard). ) Observed from the integral ratio of the methyl proton and methylene proton signal derived from the methoxyacetyl group, the proton signal derived from the alkyl group, and the proton signal derived from the introduced (meth) acryloyl group.
For the NMR measurement, “FT-NMR LA-400” (manufactured by JEOL Ltd.) is used.

  As a method for producing a reactive group-containing cellulose derivative according to the present invention, for example, a raw material cellulose derivative represented by the following formula (3) is reacted with an acid halide having an acryloyl group or a methacryloyl group, and the hydroxyl group of the raw material cellulose derivative is thus reacted. This is done by replacing. More specifically, the raw material cellulose derivative is dissolved in a suitable solvent and reacted with an acid halide having an acryloyl group or a methacryloyl group.

[In said formula (3), R < ¹ > shows a hydrogen atom, an ethyl group, or a propyl group. n represents an integer of 2 or more. ]

  A basic solvent is particularly preferably used as the solvent and at the same time makes the solution basic. The basic solvent is a solvent that plays a role of receiving protons, such as morpholine, acetylmorpholine, pyridine, N-methyl-2-pyrrolidone, α-picoline, β-picoline, γ-picoline, 2,4-lutidine. 2,6-lutidine, piperidine, pyrrolidine, quinoline, isoquinoline, 4-dimethylaminopyridine, tertiary amine and the like. These basic solvents can be used alone or in combination of two or more. The amount of the basic solvent used is preferably 1.0 mol or more per 1.0 mol of acid halide, and more preferably 1.1 to 5.0 mol from the viewpoint of reactivity.

The following organic solvents may be added as necessary within the range not impairing the reactivity between the hydroxyl group of the raw material cellulose derivative and the acid halide.
Examples of the organic solvent include N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, dipropyl sulfoxide, dipropyl sulfoxide, methyl ethyl ketone, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, benzene, toluene, xylene, hexaneheptane. Etc. These organic solvents can be used alone or in combination of two or more.

  The reaction is preferably performed in a homogeneous system in which the raw material cellulose derivative is uniformly dissolved in a solvent from the viewpoint of increasing the esterification rate. Similarly, from the viewpoint of increasing the esterification rate by reacting in a homogeneous system, the concentration of the raw material cellulose derivative in the reaction solution is preferably 0.01 to 5.0% by mass, more preferably 0.1%. It is -4.5 mass%, More preferably, it is 1.0-4.0 mass%.

  The reaction temperature is preferably 0 to 150 ° C, particularly preferably 30 to 120 ° C, from the viewpoint of the thermal stability of the raw material cellulose derivative and the reactivity of the hydrophobizing agent. The reaction time is preferably 0.5 to 30 hours. The obtained cellulose derivative can be purified by drying after washing with ethanol or the like, if necessary.

The weight average molecular weight of the raw material cellulose derivative is preferably 80,000 to 300,000, more preferably 80,000 to 220,000 as a value with which a thickening effect can be expected with a small amount.
Moreover, it is preferable that the weight average molecular weights of a reactive group containing cellulose derivative are 80,000-300,000, More preferably, it is 80,000-220,000.
This weight average molecular weight is measured by “HLC-8220” (manufactured by Tosoh Corporation).

The content of the thickener component is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass in the protective layer forming coating solution.
In the case where the content of the thickener component is too small, a sufficient liquid viscosity cannot be obtained in the protective layer forming coating solution, resulting in uneven coating, a desired layer thickness, and There is a possibility that a protective layer having a uniform layer thickness cannot be formed. On the other hand, when the content of the thickener component is excessive, the crosslinking density is lowered, and there is a possibility that sufficient strength cannot be secured for the protective layer to be formed.

Examples of the method for polymerizing the polymerizable compound component and the thickener component in the coating solution for forming the protective layer include a method of irradiating active rays such as ultraviolet rays and electron beams. Specifically, the reaction is performed by electron beam cleavage. And a method of adding a polymerization initiator and reacting with light, heat, or the like.
As a polymerization method of the polymerizable compound component and the thickener component, a method of reacting with ultraviolet rays is particularly preferable from the viewpoint of ease of use.

The ultraviolet light source is not particularly limited as long as it is a light source that generates ultraviolet light. Is mentioned.
Irradiation conditions vary depending on the type of each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² . The power of the lamp is preferably 0.1 to 5 kW, more preferably 0.5 to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage of electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary irradiation amount of active rays is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

(Polymerization initiator)
As the polymerization initiator used in the step (4), any of a photopolymerization initiator and a thermal polymerization initiator can be used. Moreover, a photoinitiator and a thermal polymerization initiator can also be used together.

  Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2-methyl). Azo compounds such as butyronitrile); benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, etc. And peroxides.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (“Irgacure 369” manufactured by BASF Japan Ltd.), 2-hydroxy-2 -Methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) Acetophenone or ketal photoinitiators such as oximes; benzoin, benzoin methyl ether Benzoin ether photopolymerization initiators such as benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether; benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyl Benzophenone photopolymerization initiators such as phenyl ether, acrylated benzophenone, 1,4-benzoylbenzene; 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4- Examples thereof include thioxanthone photopolymerization initiators such as dichlorothioxanthone.

  Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine Compounds, triazine compounds, imidazole compounds and the like. In addition, a photopolymerization accelerator having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. Examples of the photopolymerization accelerator include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, and 4,4′-dimethylaminobenzophenone. Etc.

  The polymerization initiator used in the present invention is preferably a photopolymerization initiator, preferably an alkylphenone compound or a phosphine oxide compound, more preferably a polymerization initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure. Agents are preferred.

  It is preferable that the addition amount of a polymerization initiator is 0.1-30 mass parts with respect to 100 mass parts of polymeric compound components, More preferably, it is 0.5-10 mass parts.

(solvent)
Examples of the solvent used in the step (4) include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, and cyclohexane. , Ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine, but are not limited thereto.

(Metal oxide fine particles)
The coating liquid for forming the protective layer preferably contains metal oxide fine particles for the purpose of imparting high durability to the formed protective layer.
Such metal oxide fine particles may be metal oxide particles including transition metals. For example, silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), tin oxide, oxide Metal oxides such as tantalum, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium dioxide, niobium oxide, molybdenum oxide, vanadium oxide Among these, fine particles of alumina (Al ₂ O ₃ ), tin oxide (SnO ₂ ), and titanium dioxide (TiO ₂ ) are preferable, and alumina and tin oxide are more preferable.

The number average primary particle size of the metal oxide fine particles is preferably in the range of 1 to 300 nm, more preferably 3 to 100 nm.
In the present invention, the number average primary particle size of the metal oxide fine particles is measured as follows.
That is, a 10000 times magnified photograph was taken with a scanning electron microscope “JSM-7500F” (manufactured by JEOL Ltd.), and a photographic image (excluding aggregated particles) obtained by randomly capturing 300 metal oxide fine particles with a scanner. Calculation is performed using an automatic image processing analysis apparatus “LUZEX AP” (software version Ver. 1.32, manufactured by Nireco).

  The means for dispersing the metal oxide fine particles is not particularly limited, and examples thereof include a disperser such as an ultrasonic disperser, a ball mill, a sand grinder, and a homomixer.

20-400 mass parts is preferable with respect to 100 mass parts of polymeric compound components, and, as for content of metal oxide microparticles | fine-particles, More preferably, it is 50-300 mass parts.
When the content of the metal oxide fine particles is too small, the electrical resistance of the protective layer to be formed becomes low, and it may not be possible to prevent an increase in residual potential and occurrence of fog. On the other hand, when the content of the metal oxide fine particles is excessive, there is a possibility that good film formability cannot be obtained in the formed protective layer, and it is impossible to prevent deterioration of charging performance or occurrence of pinholes. is there.

The metal oxide fine particles are preferably those that have been surface-treated with a surface treatment agent having a reactive group (hereinafter also referred to as “reactive group-containing surface treatment agent”). Alumina fine particles or tin oxide fine particles surface-treated with a treating agent are preferred.
Such a reactive group-containing surface treatment agent may be any one having reactivity with a hydroxyl group or the like present on the surface of the metal oxide fine particles, and specifically, one having an acryloyl group or a methacryloyl group is preferable.
When the metal oxide fine particles are surface-treated with the reactive group-containing surface treatment agent, the bond with the polymerizable compound component becomes strong, and the formed protective layer has higher durability. .

  Specific examples of the reactive group-containing surface treatment agent include those shown in the following exemplary compounds S-1 to S-36.

Exemplary Compound S-1: CH ₂ ═CHSi (CH ₃ ) (OCH ₃ ) ₂
Exemplary Compound S-2: CH ₂ ═CHSi (OCH ₃ ) ₃
Exemplary compound S-3: CH ₂ ═CHSiCl ₃
Exemplary Compound S-4: CH ₂ ═CHCOO (CH ₂ ) ₂ Si (CH ₃ ) (OCH ₃ ) ₂
Exemplified Compound _{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
Exemplified compound _{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
Example Compound _{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
Exemplary Compound S-8: CH ₂ ═CHCOO (CH ₂ ) ₂ Si (CH ₃ ) Cl ₂
Exemplary Compound S-9: CH ₂ ═CHCOO (CH ₂ ) ₂ SiCl ₃
Example Compound _{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
Exemplary Compound S-11: CH ₂ ═CHCOO (CH ₂ ) ₃ SiCl ₃
Exemplified compound _{S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
Exemplified compound _{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
Example Compound _{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
Exemplified compound _{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
Exemplified compound _{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
Exemplary Compound S-17: CH ₂ ═C (CH ₃ ) COO (CH ₂ ) ₂ SiCl ₃
Example Compound _{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
Exemplary Compound S-19: CH ₂ ═C (CH ₃ ) COO (CH ₂ ) ₃ SiCl ₃
Example Compound _{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
Exemplary Compound S-21: CH ₂ ═C (CH ₃ ) Si (OCH ₃ ) ₃
Example Compound _{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
Example Compound _{S-23: CH 2 = CHSi} (OCH 3) 3
Example Compound _{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
Exemplary Compound S-25: CH ₂ ═CHSi (CH ₃ ) Cl ₂
Example Compound _{S-26: CH 2 = CHCOOSi} (OCH 3) 3
Example Compound _{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
Example Compound _{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
Example Compound _{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
Example Compound _{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
Exemplified compound _{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
Example Compound _{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
Example Compound _{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
Example Compound _{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
Example Compound _{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
Example Compound _{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2

Moreover, as a surface treating agent, the silane compound which has a reactive group in which radical polymerization reaction is possible other than what is shown to the said exemplary compound S-1 to S-36 can be used.
These silane compounds can be used alone or in combination of two or more.

  The surface treatment method using a reactive group-containing surface treatment agent for metal oxide fine particles is not particularly limited, and wet treatment or dry treatment can be adopted, but treatment using a wet media dispersion type apparatus is preferable. .

Hereinafter, a surface treatment method using a wet media dispersion type apparatus will be specifically described.
That is, by subjecting a slurry (suspension of solid particles) containing metal oxide fine particles and a reactive group-containing surface treatment agent to wet pulverization, the metal oxide fine particles are refined and the surface treatment of the metal oxide fine particles is performed. Progresses. After that, the surface-treated metal oxide fine particles are obtained by removing the solvent and pulverizing.

  In the surface treatment method as described above, the addition amount of the reactive group-containing surface treatment agent is 0.1 to 100 parts by mass with respect to 100 parts by mass of the metal oxide fine particles, and the addition amount of the solvent is the metal oxide fine particles. It is preferable that it is 50-5000 mass parts with respect to 100 mass parts.

Wet media dispersion type device is a device that crushes and disperses the aggregated particles of metal oxide by filling beads in the container as media and rotating the stirring disk mounted perpendicular to the rotation axis at high speed. The structure is not particularly limited as long as the metal oxide fine particles can be sufficiently dispersed and subjected to the surface treatment when the surface treatment is performed on the metal oxide fine particles. For example, vertical and horizontal types, Various modes such as a continuous type and a batch type can be adopted. Specifically, a sand mill, an ultra visco mill, a pearl mill, a glen mill, a dyno mill, an agitator mill, a dynamic mill, or the like can be used.
In these dispersion-type apparatuses, pulverization and dispersion are performed by impact crushing, friction, shearing, shear stress, and the like using a pulverizing medium (media) such as balls and beads.

  Examples of the beads used in the wet media dispersion type apparatus include pulverization media made of glass, alumina, zircon, zirconia, steel, flint stone, etc., and those made of zirconia or zircon are particularly preferable. The size of the beads is usually about 1 to 2 mm in diameter, but in the present invention, about 0.1 to 1.0 mm is preferable.

  For example, stainless steel, nylon, and ceramic materials are used for the stirring disk and the inner wall of the container used in the wet media dispersion type apparatus, but ceramic materials such as zirconia or silicon carbide are particularly preferable.

  By the surface treatment with the reactive group-containing surface treatment agent as described above, metal oxide fine particles having a reactive group capable of reacting with a reactive acryloyl group and a reactive methacryloyl group can be obtained.

  The coating liquid for forming the protective layer may contain lubricant particles, a charge transport material, an antioxidant and the like as necessary.

(Lubricant particles)
Examples of the lubricant particles include fluorine atom-containing resin particles. Examples of the fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorinated ethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these It is preferable to select one or two or more of these copolymer particles as appropriate, but tetrafluoroethylene resin particles and vinylidene fluoride resin particles are particularly preferable.

The number average primary particle size of the lubricant particles is preferably 0.01 to 1 μm, more preferably 0.05 to 0.5 μm.
In the present invention, the number average primary particle size of the lubricant particles is measured as follows.
In other words, a 10000x magnified photograph was taken with a scanning electron microscope "JSM-7500F" (manufactured by JEOL Ltd.), and a photographic image (excluding aggregated particles) obtained by randomly capturing 300 lubricant particles with a scanner was automatically displayed. Calculation is performed using a processing analysis apparatus “LUZEX AP” (software version Ver. 1.32, manufactured by Nireco).

  The molecular weight of the resin constituting the lubricant particles can be appropriately selected and is not particularly limited.

  The content of the lubricant particles is preferably 0.1 to 20% by mass, more preferably 0.2 to 10% by mass in the protective layer forming coating solution.

The liquid viscosity of the protective layer-forming coating solution is preferably 5 to 50 mP · s, more preferably 10 to 25 mP · s.
When the viscosity of the coating liquid for forming the protective layer is too small, coating unevenness occurs, and there is a possibility that a protective layer having a desired layer thickness and a uniform layer thickness cannot be formed. . On the other hand, when the liquid viscosity of the coating liquid for forming the protective layer is excessive, good fluidity cannot be obtained in the coating liquid for forming the protective layer, causing liquid breakage on the coated surface and forming a uniform coated film. There is a risk that it cannot be done.
The liquid viscosity of the coating liquid for forming the protective layer is measured using “E-type viscometer VISCONIC ELD type” (manufactured by Tokyo Keiki Co., Ltd.).

  Examples of the method for applying the coating liquid for forming the protective layer include known methods such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a slide hopper method. Among these, the application method by the slide hopper method is preferable.

  Hereinafter, a method of applying by a slide hopper method using a circular slide hopper applicator will be specifically described.

FIG. 1 is an explanatory cross-sectional view showing an example of the configuration of a circular slide hopper coating apparatus used in the protective layer forming step in the method for producing an organic photoreceptor of the present invention, and FIG. 2 is a circular slide hopper shown in FIG. It is a perspective sectional view of a coating device.
This circular slide hopper coating apparatus includes a cylindrical base material 251, an annular coating head 260 provided so as to surround the periphery thereof, and a storage tank 254 that stores the coating liquid L.

  The substrate 251 here is a substrate for forming a protective layer to which a coating solution for forming a protective layer is to be applied. For example, the substrate 251 has a state in which an intermediate layer and an organic photosensitive layer are formed on a conductive support. Thus, the protective layer is not formed.

The coating head 260 has a narrow coating liquid distribution slit 262 having a coating liquid outlet 261 that opens to the base 251 side along the entire direction of the annular coating head 260 along the direction perpendicular to the longitudinal direction of the base 251. Is formed over. The coating liquid distribution slit 262 communicates with the annular coating liquid distribution chamber 263, and the coating liquid distribution chamber 263 is supplied with the coating liquid L in the storage tank 254 through the supply pipe 264 by the pumping pump 255. Is formed.
On the lower side of the coating liquid outlet 261 of the coating liquid distribution slit 262, there is formed a slide surface 265 that is continuously inclined downward and is formed with a dimension slightly larger than the outer dimension of the substrate 251. Furthermore, a lip portion (bead; liquid reservoir portion) 266 extending downward from the end of the slide surface 265 is formed.

  In such a circular slide hopper coating apparatus, when the coating liquid L is pushed out from the coating liquid distribution slit 262 and allowed to flow down along the slide surface 265 in the process of moving the base 251 in the direction of the arrow, the slide surface 265 ends. The resulting coating liquid L forms a bead between the end of the slide surface 265 and the outer peripheral surface of the substrate 251, and is then applied to the surface of the substrate 251 to form a coating film F. Is discharged from the discharge port 267.

  In such a coating method using a circular slide hopper coating apparatus, the slide surface end and the base material are arranged with a certain gap (about 2 μm to 2 mm), so that the base material is not damaged and the layers have different properties. Even in the case of forming a multilayer, it can be applied without damaging the already applied layer. Furthermore, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter than in the dip coating method. Since it can be applied without elution, for example, it can be applied without deteriorating the dispersibility of the metal oxide fine particles.

Drying of the coating film of the coating solution for forming the protective layer can be performed before and after irradiating with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining them.
The method for drying the coating film of the coating liquid for forming the protective layer can be appropriately selected depending on the type of the solvent, the layer thickness of the protective layer to be formed, etc. The drying temperature is preferably room temperature to 180 ° C., for example. More preferably, it is 80-140 degreeC. The drying time is preferably, for example, 1 to 200 minutes, and more preferably 5 to 100 minutes.

  The thickness of the protective layer formed by the step (4) is preferably 0.2 to 10 μm, more preferably 0.5 to 5 μm.

The protective layer formed by this process (4) can also be comprised using together well-known resin with the cured resin formed by a polymeric compound component.
Examples of known resins include polyester resins, polycarbonate resins, polyurethane resins, acrylic resins, epoxy resins, silicone resins, alkyd resins, and the like.

[Image forming apparatus]
The organic photoreceptor obtained by the production method of the present invention can be used in various known electrophotographic image forming apparatuses such as a monochrome image forming apparatus and a full color image forming apparatus.
The image forming apparatus using the organic photoreceptor according to the present invention includes, for example, a charging unit that applies a uniform charging potential on the organic photoreceptor, and an electrostatic latent image on the organic photoreceptor to which the uniform charging potential is applied. A developing unit that develops the electrostatic latent image with a toner and visualizes the toner image, a transfer unit that transfers the toner image onto the transfer material, and a toner image on the transfer material that is fixed. The image forming apparatus includes a fixing unit and a cleaning unit that removes toner remaining on the organic photoreceptor.

〔toner〕
The electrostatic latent image formed on the organic photoreceptor obtained by the production method of the present invention is visualized as a toner image by development. The toner used for the development may be a pulverized toner or a polymerized toner, but a polymerized toner produced by a polymerization method is preferable from the viewpoint of obtaining a stable particle size distribution.

  Polymerized toner is formed by the formation of a binder resin (hereinafter also referred to as “binder resin for toner”) and the shape of the toner by polymerization reaction of the raw material monomer of the toner binder resin and, if necessary, subsequent chemical treatment. Specifically, it means a material formed through a polymerization reaction such as suspension polymerization or emulsion polymerization and, if necessary, a step of fusing the particles thereafter.

The particle diameter of the toner particles constituting the toner is preferably 2 to 9 μm, more preferably 3 to 7 μm in terms of volume average particle diameter (Dv50).
When the particle diameter of the toner particles is in the above range, the resolution of the formed image can be increased. Furthermore, although the toner particles have a small particle size, the abundance of fine toner particles can be reduced, the dot image reproducibility is improved over a long period of time, and a stable image with good sharpness. Can be formed.
The volume average particle diameter (Dv50) of the toner particles is measured and calculated using a measuring device in which a computer system for data processing (manufactured by Beckman Coulter) is connected to “Multisizer 3” (manufactured by Beckman Coulter). Is.

(Developer)
The toner according to the present invention may be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. can do.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable.

The magnetic particles constituting the carrier preferably have a volume average particle size (Dv50) of 15 to 100 μm, more preferably 25 to 80 μm.
In the present invention, the volume average particle diameter (Dv50) of the magnetic particles is measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser. is there.

  The carrier is preferably a resin-coated type in which magnetic particles are further coated with a resin, or a so-called resin-dispersed type in which magnetic particles are dispersed in a resin. The coating resin for constituting the resin-coated carrier is not particularly limited. For example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, fluorine-containing resin Examples thereof include polymer resins. In addition, the dispersing resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, styrene-acrylic resin, polyester resin, fluorine resin, phenol resin Etc.

  According to the method for producing an organophotoreceptor of the present invention, by having a step of applying a protective layer forming coating solution containing a polymerizable compound component and a thickener component that undergoes a polymerization reaction with the polymerizable compound component. When the protective layer-forming coating liquid having an appropriate liquid viscosity is applied to form a coating film having an appropriate film thickness, and when the polymerizable compound component in the coating film is cured by polymerization reaction, Since the thickener component itself is incorporated into the polymerization reaction system, an organic photoreceptor in which the protective layer has a desired layer thickness while the protective layer has sufficient strength can be obtained. Therefore, according to the method for producing an organophotoreceptor of the present invention, it is possible to increase the thickness of the protective layer without reducing the strength of the protective layer. Occurrence of image defects due to this is suppressed, and an organic photoreceptor capable of forming a high-quality image is obtained. Moreover, since the coating liquid for forming the protective layer has an appropriate liquid viscosity, the occurrence of coating unevenness can be suppressed, and a protective layer having a uniform layer thickness can be formed. Generation of density unevenness can be suppressed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Synthesis example 1 of thickener component]
Into a four-necked separable flask equipped with a stirrer, a Dimroth reflux condenser and a thermometer, 10 g of ethyl cellulose “Ethocel 100 (average molecular weight: 190,000)” (manufactured by Dow Chemical Co., Ltd.) as a raw material (raw cellulose derivative) Dissolved in 700 g of chloroform. To this, 100 g of pyridine and 0.1 g of 4-dimethylaminopyridine were added, and the temperature was raised to 50 ° C. After these were completely dissolved, 11 g of acrylic acid chloride was added over 30 minutes and reacted at 50 ° C. for 20 hours. After washing with ethanol, about 8 g of a reactive group-containing cellulose derivative [1] composed of ethyl cellulose acrylate was obtained. The average substitution degree of the reactive group of this reactive group-containing cellulose derivative [1] was 1.0 per glucose unit.
In addition, ethyl cellulose as a raw material cellulose derivative had an average ethyl group substitution degree of 1.45 per glucose unit.

[Synthetic Examples 2 to 15 of the thickener component]
In Synthesis Example 1 of the thickener component, the raw material cellulose derivative is changed to the type shown in Table 1, and when an acryloyl group is introduced, acrylic acid chloride or methacryloyl group is introduced. Reactive group-containing cellulose derivatives [2] to [15] were obtained in the same manner except that the addition amount shown in 1 was changed. Table 1 shows the average degree of substitution of reactive groups and the types of reactive groups in the obtained reactive group-containing cellulose derivatives [2] to [15].

[Example 1: Production Example 1 of Organic Photoreceptor]
(1) Production of conductive support The surface of a drum-like aluminum support was cut to produce a conductive support [1] having a surface roughness Rz = 1.5 (μm).

(2) Intermediate layer forming step Using a sand mill with the following raw materials as a disperser, dispersion was performed for 10 hours by a batch method to prepare an intermediate layer forming coating solution [1].
-Binder resin: Polyamide resin "X1010" (manufactured by Daicel Degussa) 1 part by mass-Solvent: 20 parts by mass of ethanol-Metal oxide fine particles: Titanium oxide fine particles "SMT500SAS" (manufactured by Teika) with a number average primary particle size of 0.035 µm 1.1 parts by mass On the conductive support [1], the intermediate layer-forming coating solution [1] is applied by a dip coating method to form a coating film, and the coating film is formed at 110 ° C. for 20 minutes. Dried to form an intermediate layer [1] having a layer thickness of 2 μm.

(3) Organic photosensitive layer forming step (charge generating layer forming step)
Dispersion for 10 hours was performed using a sand mill with the following raw materials as a disperser to prepare a coating solution [1] for forming a charge generation layer.
Charge generating material: titanyl phthalocyanine pigment (having a maximum diffraction peak at a position of 5 at least 27.3 ° by Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts by mass Binder resin: polyvinyl butyral resin “# 6000-C (Electric Chemical Industry Co., Ltd.)
10 parts by mass / solvent: 700 parts by mass of t-butyl acetate / solvent: 300 parts by mass of 4-methoxy-4-methyl-2-pentanone On the intermediate layer [1], this coating solution for forming a charge generation layer [1] ] Was applied by a dip coating method to form a coating film, and a charge generation layer [1] having a layer thickness of 0.3 μm was formed.

(Charge transport layer forming step)
The following raw materials were mixed and dissolved to prepare a charge transport layer forming coating solution [1].
-Charge transport material: 150 parts by mass of the compound represented by the following formula (A)-Binder resin: 300 parts by mass of polycarbonate resin "Z300" (manufactured by Mitsubishi Gas Chemical Company)-Solvent: Toluene / tetrahydrofuran = 1/9% by volume 2000 parts by mass Antioxidant: “Irganox 1010” (manufactured by Ciba Geigy Japan) 6 parts by mass Leveling agent: Silicone oil “KF-54” (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass On the charge generation layer [1], this charge transport The layer forming coating solution [1] was applied by a dip coating method to form a coating film, and this coating film was dried at 120 ° C. for 70 minutes to form a charge transport layer [1] having a layer thickness of 20 μm.

(4) Protective layer forming step The following polymerizable compound component, thickener component, solvent, polymerization initiator and metal oxide fine particles are dispersed for 10 hours using a sand mill as a disperser under light shielding to form a protective layer. Coating solution [1] was prepared.
-Polymerizable compound component: 100 parts by weight of the compound shown in the exemplified compound 42-Thickener component: 3 parts by weight of reactive group-containing cellulose derivative-Solvent: 500 parts by weight of sec-butanol-Polymerization initiator: "Irgacure 369 "(manufactured by BASF Japan Ltd.) 5 parts by mass, metal oxide fine particles: 100 parts by mass of tin oxide fine particles having a number average primary particle size of 20 nm and surface-treated with the surface treating agent shown in Exemplary Compound S-15 The coating liquid [1] was applied onto the charge transport layer [1] using a circular slide hopper coating apparatus shown in FIG. 1 to form a coating film. Thereafter, this coating film was dried at room temperature for 20 minutes, and a metal halide lamp was used to irradiate ultraviolet rays for 1 minute at a lamp output of 4 kW with a separation distance between the light source and the photoreceptor surface of 100 mm under a nitrogen stream. A protective layer [1] of 3.5 μm was formed to obtain an organic photoreceptor [1].

[Examples 2 to 14 and Comparative Examples 1 and 2: Production Examples 2 to 16 of Organic Photoreceptor]
In Production Example 1 of the organophotoreceptor, (4) The polymerizable compound component, the thickener component, and the metal oxide fine particles in the protective layer forming step were changed to the types and addition amounts shown in Table 2 in the same manner. Organic photoreceptors [2] to [16] were obtained.

  The organic photoreceptors [1] to [16] obtained as described above were subjected to a full-color image forming apparatus “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies, Inc .; exposure, reversal development, intermediate transfer member of 780 nm semiconductor laser) The following evaluations 1 to 3 were performed. The results are shown in Table 3.

[Evaluation 1: Image uniformity]
1. A4 plate image with 5% print area ratio for each color of yellow (Y), magenta (M), cyan (C), and black (K) under the conditions of temperature 20 ° C. and humidity 50% RH on A4 plate neutral paper. After printing 50,000 sheets, a halftone image (relative reflection density of 0.4 with Macbeth densitometer) was printed on the entire surface of A3 neutral paper. The density difference (ΔHD = maximum density−minimum density) of the printed image was evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: ΔHD is 0.05 or less (good)
○: ΔHD is larger than 0.05 and smaller than or equal to 0.075 (no practical problem)
Δ: ΔHD greater than 0.075 and less than 0.1 (practical)
×: ΔHD is larger than 0.1 (practical problem)

[Evaluation 2: Scratch resistance]
After the evaluation of the uniformity of the above image, an A4 size image with a color printing area ratio of 5% for each of yellow (Y), magenta (M), cyan (C), and black (K) under the conditions of a temperature of 20 ° C. and a humidity of 50% RH. 1 million sheets were printed on A4 neutral paper. Thereafter, a halftone image (relative reflection density of 0.4 with Macbeth densitometer) was printed on the entire surface of A3 neutral paper. Thereafter, the organic photoreceptor and the formed halftone image were observed and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: No noticeable scratches are observed on the surface of the organic photoreceptor, and no image defects corresponding to the scratches are found in the halftone image (good).
○: Minor scratches are visually observed on the surface of the organophotoreceptor, but no image defects corresponding to the scratches are found in the halftone image (no problem in practical use).
×: The surface of the organic photoconductor is clearly scratched, and the occurrence of image defects corresponding to the scratch is also observed in the halftone image (practically problematic).

[Evaluation 3: Abrasion resistance]
Under the conditions of the initial organic photoconductor thickness, temperature 20 ° C., humidity 50% RH, yellow (Y), magenta (M), cyan (C), black (K) A4 version with 5% each color printing area ratio The film thickness of the organic photoconductor after printing 1 million sheets of images on A4 neutral paper was measured, and this film thickness difference was evaluated according to the following evaluation criteria as the amount of wear of the protective layer of the organic photoconductor.
In addition, the film thickness of the organic photoconductor was measured at 10 points at random on the uniform film thickness portion (the film thickness tends to be non-uniform at both ends of the organic photoconductor), and the average value thereof was measured. Was the film thickness of the organic photoreceptor. The film thickness was measured using an eddy current film thickness measuring instrument “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO).
-Evaluation criteria-
A: The amount of wear is 1 μm or less (good)
○: Amount of wear is greater than 1 μm and less than 3 μm (no problem in practical use)
X: The amount of wear is larger than 3 μm (there is a practical problem)

251 Substrate 254 Storage tank 255 Pressure pump 260 Application head 261 Application liquid outlet 262 Application liquid distribution slit 263 Application liquid distribution chamber 264 Supply pipe 265 Slide surface 266 Lip portion 267 Discharge port L Application liquid F Application film

Claims (6)

A method for producing an organic photoreceptor in which an organic photosensitive layer and a protective layer are laminated in this order on a conductive support,
Protective layer forming coating solution comprising a polymerizable compound component having a reactive group to form a cured resin constituting the protective layer, and a thickener component having a reactive group that undergoes a polymerization reaction with the polymerizable compound component It has a step of applying a,
The polymerizable compound component comprises a compound having an acryloyl group or a methacryloyl group as a reactive group,
The thickener component comprises a compound having an acryloyl group or a methacryloyl group as a reactive group,
The cured resin constituting the protective layer is formed by polymerizing a reactive group of the polymerizable compound component and a reactive group of the thickener component to cure. A method for producing an organic photoreceptor. The method for producing an organic photoreceptor according to claim 1, wherein the thickener component having a reactive group comprises a cellulose derivative having a reactive group . The method for producing an organic photoreceptor according to claim 1, wherein the thickener component is contained in the protective layer forming coating solution in a proportion of 0.1 to 5% by mass. . The method for producing an organic photoreceptor according to any one of claims 1 to 3, wherein the coating liquid for forming the protective layer contains metal oxide fine particles . 5. The method for producing an organophotoreceptor according to claim 4 , wherein the metal oxide fine particles are alumina fine particles or tin oxide fine particles surface-treated with a surface treatment agent having a reactive group . 6. The method for producing an organic photoreceptor according to claim 5 , wherein the surface treatment agent has an acryloyl group or a methacryloyl group as a reactive group .