KR20110050012A - Charge-transporting material for organic photo conductor and organic photo conductor including the same - Google Patents

Abstract

PURPOSE: A charge-transporting material for an electro-photographic photosensitive unit and the electro-photographic unit are provided to stabilize a photosensitive layer and increase the sensitivity of the photosensitive unit. CONSTITUTION: A charge-transporting material for an electro-photographic photosensitive unit includes a compound represented by chemical formula 1. The electro-photographic photosensitive unit includes a conductive support, a charge transporting material, and a photosensitive layer. The photosensitive layer includes a charge generation layer and a charge transporting layer. The charge transporting material is included in the charge transporting layer.

Description

Charge-transporting material for organic photo conductor and organic photo conductor including the same}

The present invention relates to an electrophotographic photosensitive member having a charge transport material for forming a photosensitive layer and a photosensitive layer formed using the same. More specifically, the present invention exhibits high sensitivity and low residual potential for LED light and semiconductor laser light, which are used in a variety of laser printers, copiers, fax machines, and the like, and an electrophotographic photosensitive member and a photosensitive layer formed with excellent film stability of the photosensitive layer. It relates to a charge transport material in the composition.

In recent years, electrophotographic technology has been widely used and applied not only to the copier area but also to various printers and printer areas, in particular because it can produce high quality images with immediateness.

Electrophotographic photoconductor The photoconductive material used includes an inorganic photoconductive material and an organic photoconductive material. Commonly used photoconductive materials are inorganic photoconductive materials such as selenium, arsenic-selenium alloys, cadmium sulfide, and zinc oxide, and the current mainstream does not involve any contamination, guarantees easy film-forming, and easily Various photoreceptors using organic photoconductive materials having advantages such as being manufactured have been developed, and organic photoconductive materials having high charge mobility as well as increasingly high charge generating materials have been proposed.

In the photosensitive layer structure of an electrophotographic photosensitive member, a charge generating material and a charge transporting material are contained in the same layer, and the single layer type electrophotographic photosensitive member dispersed in a binder resin, and a function of generating a charge carrier by different compounds, and Background Art A stacked photosensitive layer is known in which a function of transporting a charge carrier is performed separately. Currently, most of the functional separation type stacked electrophotographic photosensitive members have been put to practical use and are widely used.

In the laminated electrophotographic photosensitive member, high sensitivity charge generating materials showing high charge generation efficiency have been continuously developed, and in combination with development of high sensitivity charge generating materials, a combination with a charge transport material having high charge transfer ability is important. It is a challenge.

In addition, the properties required for the charge transport material used in the electrophotographic photosensitive member are such that, by light irradiation under electric field application, the charge generated in the charge generating material must be effectively received, and the charges must be quickly moved to the surface, that is, the surface potential For the rapid disappearance of, it is important to allow the charge to move faster through the photoreceptor layer.

More specifically, the rate at which charge moves per unit electric field is called charge mobility, which is inherent in charge transport materials. High charge mobility means that charge travels quickly through the charge transport layer. Therefore, in order to obtain high charge mobility, it is necessary to use a material showing high charge mobility, and to satisfy this, a charge transport material having high charge mobility must be developed.

In addition, even if both the charge generating material and the charge transport material have excellent photoconductive properties, both the monolayer electrophotographic photosensitive member and the stacked electrophotographic photosensitive member are both charge transport materials (or charge transport layers) from the charge generating material (or charge generating layer). It is very important that the charge injection into the C) be performed quickly and with high efficiency. The injection of such charges depends on the properties of the interface between the charge generating material (or charge generating layer) and the charge transporting material (or charge transporting layer), and depends very much on the kind of materials constituting the interface.

Until now, charge transport materials having various characteristics have been developed, and electrophotographic photosensitive members using them have been put to practical use. Conventionally proposed charge transport materials for electrophotographic photosensitive members include the triarylamine dimer derivatives described in Japanese Patent Publication No. 58-32372. Further, as other examples, there are m-diaminobenzene derivatives described in Japanese Patent Application Laid-Open No. Hei 1-42642 and Japanese Patent Application Laid-open No. Hei 5-88389. As another example, 1,1,4,4-tetraphenyl-1,3-butadiene derivatives and tetraphenyl-1 described in JP-A-7-21646 and JP-A 5-19701, 3,5-hexatriene. In addition, there are many hydrazone derivatives, and are described in, for example, Japanese Patent Application Laid-Open No. 55-42380, Japanese Patent Application Laid-open No. 57-101844, Japanese Patent Application Laid-open No. 54-150128 and Japanese Patent Application Laid-open No. 61-23154. It is described.

However, the compounds reported so far present a variety of problems. For example, crystals precipitate after the film formation, or even if the film formation is performed well, sufficient surface potentials are not formed, dark decay phenomenon that does not sufficiently maintain the charge when exposed to a dark place occurs, It does not decrease completely after light irradiation. That is, there are problems involving low sensitivity and high residual potential.

It is an object of the present invention to provide a charge transport material for forming a photosensitive layer having high sensitivity and a reduction in residual potential, and to provide an electrophotographic photosensitive member using such a charge transport material.

An object of the present invention is to provide a charge transport material which forms a uniform organic thin film on a conductive support to form a photosensitive layer with excellent film stability, and to provide an electrophotographic photosensitive member comprising such charge transport material.

The above and other objects of the present invention can be achieved by the present invention described in detail.

In order to solve the above-mentioned problems, the inventors found that the above-mentioned problems show high charge mobility, stable photosensitive layer, high sensitivity, and reduction of residual potential when the compound of formula 1 is included in the charge transport material. Thus, the present invention has been completed.

In the present invention, the compound represented by the formula (1) used as the charge transport material of the electrophotographic photosensitive member shows high charge mobility, and the charge transport layer or the photosensitive layer including the same is homogeneous without precipitation of charge transport material crystals or formation of pinholes. The film is formed to have excellent film stability, and has the advantage of showing high sensitivity and low residual potential.

 Therefore, the photosensitive member according to the present invention can be effectively used as an electrophotographic photosensitive member of an electrophotographic image forming apparatus such as a laser printer, a digital copier, a facsimile or the like.

The present invention provides an electrophotographic photosensitive member comprising a conductive support and a photosensitive layer provided thereon, wherein the photosensitive layer contains a compound represented by the formula (1).

The photosensitive layer used in the present invention may be of a single layer type in which a charge generating material and a charge transporting material are included in the same layer, or a stacked type having a charge generating layer including a charge generating material and a charge transporting layer including a charge transporting material.

In the stacked electrophotographic photosensitive member, a charge generating layer and a charge transport layer are formed on a conductive support. The charge transport layer may be stacked on or below the charge generating layer, but it is preferred that the charge transport layer is stacked on the charge generating layer. The charge transport layer is vacuum deposited on the conductive support or the charge generating layer, or the compound and binder polymer are dissolved or dispersed in a suitable solvent, coated with a solution or a dispersion on the conductive support or charge generating layer, and then dried. Is provided.

As the binder polymer used to form the charge transport layer, any binder polymer that has conventionally been used to form the electrophotographic photosensitive member and the charge transport layer may be used. Examples include polyacrylates, polymethacrylates, polyamide resins, acrylonitrile resins, vinyl chloride resins, acetal resins, butyral resins, vinyl acetate resins, polystyrene resins, polyolefin resins, cellulose esters, phenolic resins, epoxy resins Photosetting with insulating thermoplastic and thermosetting resins such as methyl acrylic resins such as polyester resins, alkyd resins, silicone resins, polycarbonate resins, polyurethane resins, polyimide resins and copolymers or derivatives thereof (photo-setting) insulating resins. In addition to these resins, organic photoconductive polymers such as polyvinylcarbazole, polyvinylanthracene and polyvinylpyrene are also included. These binder polymers may be used independently or in combination of two or more thereof as appropriate. Of these binder polymers, polycarbonate resins are preferred.

Among the polycarbonates, preferred are bisphenol A type polycarbonates, bisphenol Z type polycarbonates and copolymerized carbonates having bisphenol A, bisphenol Z and biphenol carbonate as structural units. In addition to the bicarbonate / biphenyl type polycarbonates described above, polymeric binders incorporating siloxane units and the like are also preferred.

In the amount of mixing the binder polymer and compound 1, the amount of compound 1 is appropriately selected from the range of usually 10 to 1000 parts by weight, preferably from 50 to 200 parts by weight per 100 parts by weight of the binder polymer.

The solvent for dissolving both Compound 1 and the binder polymer is not particularly limited, but an organic solvent is preferred, and the choice of organic solvent mainly depends on the kind of binder resin. For example, alcohols such as methanol, ethanol and isopropanol ketones such as acetone, methyl ethyl ketone and cyclohexanone N, N-dimethylformamide and sulfoxides such as amides dimethyl sulfoxide such as N, N-dimethylacetamide Ethers such as tetrahydrofuran, dioxane, dioxolane, ethylene glycol, dimethyl ether, diethyl ether, diisopropyl ether and tert-butyl methyl ether, esters such as methyl acetate, methyl acetate, chloroform, Aliphatic halogenated hydrocarbons such as 1,2-dichloroethane, dichloroethylene, carbon tetrachloride and trichloroethylene aromatic halogenated hydrocarbons such as chlorobenzene and dichlorobenzene aromatic hydrocarbons such as benzene, toluene and xylene pentane, hexane, heptane, Such as octane and cyclohexane Aliphatic hydrocarbons. These solvents may be used alone or in combination of two or more solvents as appropriate.

The method of forming a charge transport layer comprising a compound of formula 1 on a conductive support or charge generating layer preferably dissolves Compound 1, a binder polymer, and other charge transport materials and various additives, as described below, as needed. By dispersing, a coating solution or dispersion may be prepared, and the solution or dispersion may be treated by a known coating method.

As a method for dispersing the components, a general dispersing method using a ball mill, a sand mill, a powder mill, a vibration mill or an ultrasonic disperser can be used. Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a wire bar coating method, a blade coating method, a roller coating method and a curtain coating method.

The charge transport layer is formed by drying after the coating process. Drying the coated film is preferably carried out by drying at room temperature, followed by heating and drying. Heating and drying can be carried out at a temperature of 30 to 200 ℃ without blowing or blowing for 5 minutes to 2 hours, preferably at a temperature of 50 to 150 ℃.

In the charge transport layer of the electrophotographic photosensitive member according to the present invention, other charge transport materials may be used together with the compound of Formula 1 as necessary. Examples of other charge transport materials include hydrazone compounds, triphenylamine dimers, distyryl compounds, tetraphenylbutadiene-based compounds, and triphenylmethanes. However, other known charge transport materials may also be used, but are not limited to the charge transport materials described above.

The charge transport layer of the electrophotographic photosensitive member of the present invention may be combined with various additives as necessary to increase the charge characteristics, the stability of the coating solution and the durability of the photosensitive member. For example, surface lubricant leveling agents dicyanovinyl compounds and carbazole derivatives such as biphenylene compounds, plasticizer silicone oils such as m-terphenyl and dibutyl terephthalate, graft silicone polymers and various fluorocarbons Potential stabilizers such as monophenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol, bisphenolic antioxidants, and amine antioxidants such as 4-diazabicyclo [2,2,2] octane Salicylic acid-based antioxidants, antioxidants such as tocopherols, ultraviolet absorbers and photosensitizers.

The thickness of the charge transport layer of the electrophotographic photosensitive member of the present invention is usually appropriately selected within the range of 5 to 50 mu m, and preferably in the range of 10 to 30 mu m.

The charge transport layer generated in this manner may be electrically connected to the charge generating layer, and may have a function of receiving charges injected from the charge generating layer in the presence of an electric field and transporting these charges to another surface of the charge transport layer.

On the other hand, in the stacked electrophotographic photosensitive member, the charge generating layer is formed by vacuum deposition or coating on the conductive support or the charge transport layer, similarly to the charge transport layer. As the charge generating material included in the charge generating layer of the electrophotographic photosensitive member of the present invention, any of those conventionally used may be used.

As the charge generating material, phthalocyanine-based compounds, azo-based compounds, azulenium salt-based compounds, pyrilium salt-based compounds, naphthoquinone-based compounds and the like which are known to generate charges with high efficiency are preferably used. Among these, phthalocyanine-based compounds are particularly widely used as charge generating materials for electrophotographic photosensitive members because of their chemical and physical stability and excellent photosensitivity. These charge generating materials may be used alone or in combination of two or more thereof. Mixed crystal means that two or more kinds of compounds are incorporated at the molecular level in the primary particles of the crystal.

Phthalocyanine-based compounds, azo-based compounds, perylene-based compounds, and polycyclic quinone-based compounds used in combination with the compound of formula 1 included in the charge transporting material having high charge mobility of the present invention will be described in more detail below. .

First of all, for phthalocyanine-based pigments, for example, alkoxy titanium phthalocyanine (Ti (OR) 2 Pc), oxo titanium phthalocyanine (TiOPc), copper phthalocyanine (CuPc), metal phthalocyanine (H 2 Pc), hydroxygallium phthalocyanine (HOGaPc) Vanadil phthalocyanine (VOPc) and chloroindium phthalocyanine (ClInPc). More specifically, TiOPc includes α-TiOPc, β-TiOPc, γ-TiOPc, m-TiOPc, Y-TiOPc, A-TiOPc, B-TiOPc and amorphous TiOPc, and as H2Pc, α-H2Pc, β-H2Pc, τ-H2Pc and x-H2Pc. Azo pigments include mono-azo compounds, bis-azo compounds and tris-azo compounds.

Forming the charge generating layer by application involves dissolving or dispersing the charge generating material in a solvent together with a binder polymer, together with various additives for preparing a coating solution, if necessary, as in the case of the formation of the charge transport layer. This is done by applying on a conductive support or on a charge transport layer and drying the film. The binder polymer and other additives used herein are the same as those previously described with respect to the formation of the charge transport layer. In addition, the special methods and conditions for forming the charge generating layer are the same as those used to form the charge transport layer.

In the tomographic electrophotographic photosensitive member of the present invention, the photosensitive layer including both the charge transport material and the charge generating material including the compound of formula 1 is supplied onto the conductive support. The charge transport materials, charge generating materials, binder polymers, and various additives used herein in forming the monolayer photosensitive layer are the same as those used to form the charge transport layer and the charge generating layer of the stacked electrophotographic photosensitive member described above.

Moreover, as a conductive support body used for the photosensitive member of this invention, the electrically conductive support body which consists of a sheet form or drum form made from metals, such as copper, aluminum, silver, iron, zinc, or nickel, or alloys thereof, Is provided by coating or vacuum depositing a layer of a conductive oxide such as a conductive polymer, indium oxide or tin oxide, and a conductive polymer, which is vacuum deposited or electrolytically plated on a film or cylinder, on a support such as glass, paper, or plastic film. An electrically conductive support is used.

In the electrophotographic photosensitive member of the present invention, an interlayer having a blocking function and an adhesive function may be provided between the conductive support and the photosensitive layer, if necessary. The intermediate layer is an electrically conductive support for the purpose of preventing phase defects during the reversal development, coating surface defects in the conductive support, improving the filling ability, improving the adhesive properties of the photosensitive layer, and improving the coating properties of the photosensitive layer. And a photosensitive layer is provided on the intermediate layer. Examples of the material for forming the intermediate layer include polyvinyl alcohol, nitrocellulose, casein, ethylene-acrylic acid copolymer, polyamide such as nylon, polyurethane, gelatin, aluminum oxide and the like. The intermediate layer may be formed according to the same method as the above-described charge transport layer by mixing the intermediate layer forming material, the solvent described above, and, if necessary, a metal oxide such as titanium oxide. The film thickness of the intermediate layer is usually appropriately selected in the range of 0.1 to 20 mu m, and preferably 0.5 to 10 mu m.

Further, in the electrophotographic photosensitive member of the present invention, a protective layer may be formed by coating on the photosensitive layer, if necessary. Such a protective layer is provided for the purpose of increasing the wear resistance of the photosensitive layer, or for the purpose of preventing the adverse effects of ozone or nitrogen oxides on the photosensitive layer.

As described above, in the present invention, the charge transport material including the compound of Formula 1 exhibits high charge mobility, and the charge transport layer or the photosensitive layer containing the same exhibits high sensitivity and low residual potential. In addition, the charge transport material including the compound of Formula 1 has a good film stability by forming a homogeneous film when forming the film, there is no problem such as precipitation of crystals, pinhole formation when forming the charge transport layer or photosensitive layer. Therefore, according to this invention, it is possible to obtain the practical electrophotographic photosensitive member which shows the outstanding photosensitive characteristic and durability.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

[Example]

1 part by weight of butyral resin [poly (vinyl butyral) BX-1, Sekisui Chemical Co.Ltd. Of oxytitanil phthalocyanine [Sensient Imaging Technologies GmbH, 06766 Bitterfeld-Wolfen, Y-TiOPc]. Preparation, same as below] 1 part by weight was added to a binder polymer solution obtained by dissolving 100 parts by weight of tetrahydrofuran, and dispersed in a ball mill with zirconia beads for 20 hours. This dispersion was applied using a dip-coating apparatus on the aluminite tube in which the aluminum surface serving as the conductive support was oxidized by force, and dried at 100 ° C. for 30 minutes to form a charge generating layer having a thickness of about 1 μm. Subsequently, the compound of Formula 1 [TAKASAGO INT'L CORP. Manufacture, T719], and 10 parts by weight of polycarbonate resin Panlite TS-2050 (manufactured by TEIJIN CHEMICALS LTD., The same below) were mixed and dissolved in 100 parts by weight of tetrahydrofuran. This solution was applied onto the charge generating layer prepared above using a dip-coating apparatus and dried at 120 ° C. for 30 minutes to form a charge transport layer having a thickness of about 25 μm, thereby preparing the electrophotographic photosensitive member A of the present invention. .

Comparative Example 1

The electrophotographic photosensitive member B of the present invention is a compound represented by the following Chemical Formula 2 instead of the compound represented by Chemical Formula 1 [TAKASAGO INT'L CORP. Manufacture, CT3] except that the photosensitive member was prepared in the same manner as in Example 1, and the overall electrostatic properties were evaluated under the same conditions. The results are summarized in Table 1 below.

Comparative Example 2

The electrophotographic photoconductor C of the present invention is a compound represented by the following Chemical Formula 3 instead of the compound represented by Chemical Formula 1. [TAKASAGO INT'L CORP. Fabrication, T405] except that the photosensitive member was prepared in the same manner as in Example 1, and the overall electrostatic properties were evaluated under the same conditions. The results are summarized in Table 1 below.

Comparative Example 3

The electrophotographic photosensitive member D of the present invention is a compound represented by the following Chemical Formula 4 instead of the compound represented by Chemical Formula 1. [TAKASAGO INT'L CORP. Manufacture, T337], except that the photosensitive member was manufactured in the same manner as in Example 1, and the overall electrostatic properties were evaluated under the same conditions. The results are summarized in Table 1 below.

[Characteristic Test Example]

The electrophotographic characteristics of electrophotographic photosensitive members A to D obtained in Examples 1 and 3 were measured by a static mode system using an electrostatic recording test apparatus model DTBUILDER CONTROLLER (same as JK TECH Co. Ltd. or less). do. That is, the electrophotographic photosensitive member is charged through corona discharge, and the surface potential V0 (unit: -v) is measured. These are held for 5 seconds in the dark (surface potential Vi in this step in -v). Then, the darkening rate (the rate of decrease of surface potential in the dark) at this time is measured. The surface potential change rate for 1 second is expressed as DD1 (%), and the surface potential change rate for 5 seconds is expressed as DD5 (%). The light is then irradiated with a tungsten halogen lamp to halve the total amount of light required to attenuate the surface potential Vi to half level, E 1/2 (lux sec), and the amount of total attenuation required to attenuate the surface potential Vi to a level of 100. E 100 (lux sec) and the surface residual potential Vr (-v) after attenuation are obtained. The result thus obtained is shown in Table 1.

Vr (V): Surface potential 10 seconds after exposure

E1 / 2 (lux sec): Exposure energy when the surface potential immediately before exposure reaches 1/2

E100 (lux sec): Exposure energy when the surface potential just before exposure is 100 V

DD1 (%): surface potential retention rate 1 sec after charging in suggestion

DD5 (%): surface potential retention rate 5 seconds after charging in suggestion

As is apparent from Table 1, in the case of the electrophotographic photosensitive member according to the present invention, it can be seen that the charging characteristics and the photosensitivity are superior to those of the photosensitive member of the comparative example. This is presumably because the photosensitive layer formed in the Example was formed using a composition comprising a high charge mobility charge transport material according to the present invention.

Claims (4)

A charge transport material for an electrophotographic photoconductor comprising a compound of formula [Formula 1]

Conductive support; And A charge transport material comprising a compound of Formula 1; And an electrophotographic photosensitive member comprising a photosensitive layer formed on the conductive support. [Formula 1]

3. The stacked electrophotographic photosensitive member according to claim 2, wherein the photosensitive layer comprises a charge generating layer and a charge transporting layer, and the charge transporting material is included in the charge transporting layer. 3. The single layer electrophotographic photosensitive member according to claim 2, wherein the photosensitive layer is one layer comprising a charge generating material and a charge transporting material.