JP2575893B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member used for an image forming apparatus such as a copying machine.

<Related Art> In recent years, in an image forming apparatus such as a copying machine using a so-called Carlson process, a charge generating material that generates charges by light irradiation and a charge transporting material that transports generated charges are used in combination. By separating the charge generation function and the charge transport function, so-called function separation type,
It is widely used because it is easy to increase the sensitivity. As the function-separated type photoreceptor, a laminated photosensitive layer including a charge generation layer containing the above-described charge generation material and a charge transport layer containing the charge transport material was formed on the surface of a conductive substrate. There are a laminate type and a single layer type in which a single layer type photosensitive layer containing a charge generation material and a charge transport material is formed on the surface of a conductive substrate.

Further, in the function-separated type photoreceptor, the entirety of the single-layer or stacked-type photosensitive layer formed on the surface of the conductive substrate is formed by bonding the functional components such as the charge generation material and the charge transport material to a binder resin. An organic photoreceptor with an organic layer contained therein,
A composite type photoreceptor having a part of the above-mentioned laminated type photosensitive layer and the above-mentioned organic layer is preferably used for a wide selection of materials, excellent productivity, and a high degree of freedom in functional design. I have.

Various synthetic resin materials are used as the binder resin constituting each of the organic layers. Particularly, polycarbonate having excellent physical properties such as mechanical strength is preferably used.

In addition, the polycarbonate has various types depending on the type of bisphenol as a raw material.
Bisphenol Z type polycarbonate [poly- (4,
4'-cyclohexylidenediphenyl) carbonate]
Is preferably used because of its excellent applicability as a coating solution and physical properties of a film.

<Problems to be Solved by the Invention> By the way, the above-mentioned bisphenol Z-type polycarbonate has a problem that adhesion to a base, particularly a surface of a conductive substrate or the like is poor, and it is easy to peel off when forming images continuously. was there.

In the above-mentioned peeling, the glass transition temperature of the layer containing bisphenol Z-type polycarbonate as a binder resin is lower than the heating temperature of the electrophotographic photosensitive member at the time of image formation (around 60 ° C.). This is considered to be because the difference in physical properties such as the coefficient of thermal expansion between the base and the base increases.

The present invention has been made in view of the above circumstances, and includes an electronic device including a layer containing bisphenol Z-type polycarbonate having excellent physical properties and the like as a binder resin and having excellent adhesion to a base. It is intended to provide a photoreceptor.

<Means and Actions for Solving the Problems> To solve the above problems, the electrophotographic photoreceptor of the present invention contains a bisphenol Z-type polycarbonate represented by the following general formula [I] as a binder resin. In an electrophotographic photosensitive member having a layer, the glass transition temperature of the layer is
It is characterized by a temperature of 62 ° C or higher.

In the electrophotographic photoreceptor of the present invention having the above configuration, since the glass transition temperature of the layer is higher than the heating temperature when the electrophotographic photoreceptor is used, the physical properties between the layer and the base even in the heated state. There is no large difference between the layers, and the adhesion of the layer to the base is high.

 Hereinafter, the present invention will be described in detail.

The structure of the present invention can be applied to an electrophotographic photoreceptor having various types of photosensitive layers including an organic layer containing bisphenol Z-type polycarbonate as a binder resin (hereinafter, referred to as a “specific layer”). It is preferably applied to the following layers which are in direct contact with the surface of a base made of a different material such as metal.

A single-layer organic photosensitive layer containing a charge generation material and a charge transport material in a binder resin and formed on the surface of a conductive substrate.

A lower layer in a laminated organic photosensitive layer in which an organic charge generation layer and an organic charge transport layer are laminated on the surface of a conductive substrate.

The charge transport layer in a composite photosensitive layer in which an organic charge transport layer is laminated on a charge generation layer formed of a thin film of a semiconductor material.

In order to set the glass transition temperature of the specific layer containing the bisphenol Z-type polycarbonate to 62 ° C. or more,
For example, a method in which the crystallinity of the polycarbonate in the layer is increased by heat-treating the specific layer to increase the glass transition temperature thereof is suitably adopted. According to such a method, the glass transition temperature of the specific layer is reduced to 62 by simply heating.
° C or higher, so no large-scale equipment is required.
The electrophotographic photoreceptor of the present invention can be easily manufactured.

The conditions of the heat treatment are not particularly limited, but the heat treatment temperature is preferably 110 ° C. or more and the heat treatment time is preferably 30 minutes or more. If the heat treatment temperature is less than 110 ° C or the heat treatment time is less than 30 minutes, the crystallinity of the polycarbonate in the specific layer cannot be sufficiently increased. The heat treatment temperature is preferably 130 ° C. or lower in order to prevent sublimation, decomposition, and the like of the functional components such as the charge generation material and the charge transport material contained in the specific layer.

The heat treatment under the above heating conditions may be performed simultaneously with the drying of the specific layer when the coating liquid containing bisphenol Z-type polycarbonate is applied to the base surface to form the specific layer, or the specific layer already dried and solidified It may be performed on layers.

In addition, another binder resin may be used in combination with the specific layer as long as it does not affect the glass transition temperature of the specific layer. Examples of the other binder resin include polycarbonates other than bisphenol Z type, such as bisphenol A type polycarbonate, and thermosetting silicone resins;
Epoxy resin; urethane resin; curable acrylic resin; alkyd resin; unsaturated polyester resin; diallyl phthalate resin; phenol resin; urea resin; benzoguanamine resin; Olefin polymers such as polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polypropylene, and ionomer; polyvinyl chloride; vinyl chloride-vinyl acetate copolymer; polyvinyl acetate; saturated polyester;
Thermoplastic urethane resin; polyarylate; polysulfone; ketone resin; polyvinyl butyral; In addition, each of the binder resins including the bisphenol Z-type polycarbonate may be used, as necessary, in addition to the specific layer, an upper layer of the stacked organic photosensitive layers, and an outermost layer of each type of photosensitive layer as needed. It is also used for forming an organic layer such as a surface protective layer formed by the above method.

The electrophotographic photoreceptor of the present invention can be configured in the same manner as the conventional one, except for the glass transition temperature of the specific layer.

For example, among the above types of photosensitive layers, in the composite type photosensitive layer, as a semiconductor material constituting a thin film used as a charge generation layer, α-Se, α-As ₂ Se ₃ , α-SeAsTe
And amorphous silicon (α-Si). The thin-film charge generation layer made of the semiconductor material can be formed on the surface of the conductive substrate by a known thin-film forming method such as a vacuum evaporation method and a glow discharge decomposition method.

When the specific layer is a single-layer organic photosensitive layer or a charge transport layer of a laminated or composite photosensitive layer, examples of the charge transport material that is additionally contained in the specific layer include tetracyanoethylene; Fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; fluorene compounds such as 9-carbazolyliminofluorene; nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride A triphenylmethane compound; 2,5-
Oxadiazole compounds such as di (4-dimethylaminophenyl) -1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole such as poly-N-vinylcarbazole Pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline; 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine;
Amine derivatives such as 3,3'-dimethyl-N, N, N ', N'-tetrakis-4-methylphenyl (1,1'-biphenyl) -4,4'-diamine; 1,1-bis (4 Conjugated unsaturated compounds such as -diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; hydrazone-based compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; N ', N'-tetrakis (3-tolyl) -1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N-
M such as bis (3-tolyl) -1,3-phenylenediamine
A phenylenediamine compound; an indole compound,
Nitrogen-containing cyclic compounds such as oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds and triazole compounds; condensed polycyclic compounds. In addition, among the above-mentioned charge transporting materials, a polymer material having photoconductivity such as poly-N-vinylcarbazole can also be used as a binder resin.

On the other hand, when the specific layer is a single-layer organic photosensitive layer or a charge-generating layer of a stacked organic photosensitive layer, the charge-generating material contained in the specific layer includes, for example, a powder of the semiconductor material. Group II-VI microcrystals such as ZnO and CdS; pyrylium salts;
Azo compounds; Bisazo compounds; Phthalocyanine compounds such as aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, titanyl phthalocyanine, etc. having crystal forms such as α-type, β-type, and γ-type; Phenylmethane compounds; sulene compounds; toluidine compounds; pyrazoline compounds; quinacridone compounds; and pyrrolopyrrole compounds. These charge generating materials can be used alone or in combination of two or more.

Among the photosensitive layers of each type described above, the content of the charge generation material with respect to 100 parts by weight of the binder resin in the single-layer type organic photosensitive layer is in the range of 2 to 20 parts by weight, particularly 3 to 15 parts by weight. It is preferably within the range. Further, the content of the charge transporting material relative to 100 parts by weight of the binder resin is preferably in the range of 40 to 200 parts by weight, particularly preferably in the range of 50 to 100 parts by weight. If the content of the charge generating material is less than 2 parts by weight or the content of the charge transporting material is less than 40 parts by weight, the sensitivity of the photoconductor may be insufficient or the residual potential may be increased. On the other hand, when the content of the charge generating material exceeds 20 parts by weight or when the content of the charge transporting material exceeds 200 parts by weight, the abrasion resistance of the photoconductor may be insufficient.

The thickness of the single-layer type organic photosensitive layer is not particularly limited, but the same as that of the conventional single-layer type organic photosensitive layer, that is, 10
It is preferably in the range of 5050 μm, especially 15-25 μm.

Among the layers constituting the laminated organic photosensitive layer, the content of the charge generation material relative to 100 parts by weight of the binder resin in the organic charge generation layer is in the range of 5 to 500 parts by weight, particularly 10 to 2 parts by weight.
Preferably it is in the range of 50 parts by weight. When the content of the charge generation material is less than 5 parts by weight, the charge generation ability is too small,
If it exceeds 500 parts by weight, there is a possibility that the adhesion to the base material and other adjacent layers may be reduced.

The thickness of the charge generation layer is not particularly limited, but is 0.01 to
It is preferably within a range of 3 μm, especially 0.1 to 2 μm.

Among the layers constituting the laminated organic photosensitive layer or the composite photosensitive layer, the content of the charge transporting material relative to 100 parts by weight of the binder resin in the charge transporting layer is in the range of 10 to 500 parts by weight, particularly 25 to 500 parts by weight. Preferably it is in the range of 200 parts by weight. If the content of the charge transporting material is less than 10 parts by weight, the charge transporting ability is not sufficient, and if it exceeds 500 parts by weight, the mechanical strength of the charge transporting layer may be reduced.

The thickness of the charge transport layer is not particularly limited, but may be 2 to 10
It is preferably within a range of 0 μm, particularly 5 to 30 μm.

Further, the surface protective layer which can be formed on the outermost layer of each type of photosensitive layer contains the binder resin as a main component, and further includes, if necessary, a conductivity-imparting material or a benzoquinone-based ultraviolet absorber. The agent can be contained in an appropriate amount.

The thickness of the surface protective layer is 0.1 to 10 μm, particularly 2 to 5 μm.
It is preferably in the range of μm.

When an antioxidant is used in combination with the organic layer of the above-described types of photosensitive layers, the surface protective layer, and the like, deterioration due to oxidation of a functional component such as a charge transport material having a structure that is easily affected by oxidation. Can be prevented.

As the antioxidant, 2,6-di-tert-butyl-
p-cresol, triethylene glycol-bis [3-
(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentane Erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-) Hydroxyphenyl) propionate], 2,2-thiobis (4-
Methyl-6-tert-butylphenol), N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,
Examples include phenolic antioxidants such as 4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene.

The conductive substrate on which the photosensitive layer of each type is formed on the surface is formed into an appropriate shape, such as a sheet or a drum, corresponding to the mechanism and structure of the image forming apparatus in which the electrophotographic photosensitive member is incorporated. You.

The conductive base material may be entirely formed of a conductive material such as metal, or the base material itself may be formed of a structural material having no conductivity, and the surface may be provided with conductivity. Is also good.

The entirety of the conductive substrate is made of a conductive material, and as the conductive material used in the former case, alumite-treated or untreated aluminum, copper, tin,
Platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium,
Metal materials such as stainless steel and brass are preferable, and particularly, aluminum subjected to anodic oxidation by the alumite sulfate method and sealed with nickel acetate is preferably used.

On the other hand, in the latter case of imparting conductivity to the surface of a substrate made of a structural material having no conductivity, the above-described metal or aluminum iodide may be applied to the surface of a synthetic resin substrate or a glass substrate. A structure in which a thin film made of a conductive material such as tin oxide, indium oxide, or the like is formed by a known film forming method such as a vacuum evaporation method or a wet plating method; A structure in which a film of a material or the like is laminated, a structure in which a substance imparting conductivity is injected into the surface of the synthetic resin base or the glass base, or the like can be employed.

The conductive substrate may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, as necessary, to increase the adhesion to the photosensitive layer.

Of the photosensitive layers of each type described above, each of the organic layers including the specific layer and the surface protective layer is prepared by adjusting the coating solution for each layer containing the above-described components, and forming these coating solutions into the above-described layer configuration. Can be formed on the conductive substrate in order for each layer, and dried or cured to form a laminate.

In preparing the coating solution, various solvents can be used depending on the type of the binder resin or the like to be used. Examples of the solvent include aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; benzene, xylene,
Aromatic hydrocarbons such as toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene, methylene chloride; methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone Alcohols such as alcohols; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;
Various solvents such as esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethyl sulfoxide, and the like, may be used alone or as a mixture of two or more. When preparing the coating liquid, a surfactant, a leveling agent, and the like may be used in combination in order to improve dispersibility, coatability, and the like.

The coating solution can be prepared by a conventional method, for example, using a mixer, a ball mill, a paint shaker, a sand mill, an attritor, an ultrasonic disperser, or the like.

<Example> Hereinafter, the present invention will be described in more detail based on examples.

Examples 1 to 3, Comparative Examples 1 and 2 100 parts by weight of poly- (4,4'-cyclohexylidenediphenyl) carbonate (manufactured by Mitsubishi Gas Chemical Company, trade name Z-200) as a binder resin, a charge generating material N, N'- as
5 parts by weight of di (3,5-dimethylphenyl) perylene 3,4,9,10-tetracarboxydiimide and 0.2 parts by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink), 3,3 'as a charge transport material -Dimethyl-N, N, N ', N'-tetrakis-4-methylphenyl (1,1'-biphenyl)-
100 parts by weight of 4,4'-diamine, 2,6- as an antioxidant
5 parts by weight of di-tert-butyl-p-cresol (manufactured by Kawaguchi Chemical Co., Ltd., trade name: Antage BHT) was mixed and dispersed with a predetermined amount of tetrahydrofuran by an ultrasonic disperser to prepare a coating solution for a single-layer type photosensitive layer. . This coating solution has an outer diameter of 78 mm x length
After coating on a 344 mm aluminum tube and drying at room temperature, it is heat-treated in a dark place under the heat treatment conditions shown in Table 1 to have a glass transition temperature shown in the table and a thickness of about 22 μm.
Thus, a drum-type electrophotographic photosensitive member having a single-layer photosensitive layer of m was prepared. The glass transition temperature was measured by differential scanning calorimetry (DSC method).

Cross-cut test The electrophotographic photoreceptor prepared in each of the above Examples and Comparative Examples was loaded into a copying machine (DC-1655 type machine, manufactured by Mita Kogyo Co., Ltd.).
After performing 0 sheets of copying processing, a 1 mm x 1 mm and a 5 mm x 5 mm grid were cut on each photoreceptor with a cutter knife.
The sheets were attached one by one, and a peeling test was performed using Nichiban Tabe to observe peeling of the photosensitive layer. And the above 1mm × 1mm, and 5m
The number of mx 5 mm grids that did not peel from the photoreceptor was recorded. In addition, in this cross-cut test, x was evaluated when 8 or more of the 16 sheets were peeled, and ○ was evaluated when less than 8 were peeled. The results are shown in the following table.

From the results in the above table, the glass transition temperature of the single-layer photosensitive layer is
All of the electrophotographic photoreceptors of Examples 1 to 3 having a temperature of 62 ° C. or higher exhibited less peeling of the photosensitive layer by a grid test and lower adhesion than Comparative Examples 1 and 2 in which the glass transition temperature was lower than the above value. It turned out to be excellent.

<Effect of the Invention> The electrophotographic photoreceptor of the present invention is configured as described above, and has a glass transition temperature of a layer containing bisphenol Z-type polycarbonate having excellent mechanical strength and the like as a binder resin. Since the heating temperature is higher than the heating temperature when the photographic photosensitive member is used, there is no large difference in physical properties between the layer and the base even in the heated state, and the adhesion of the layer to the base is high.

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor having a layer containing a bisphenol Z-type polycarbonate represented by the following general formula [I] as a binder resin, wherein the layer has a glass transition temperature of 62 ° C. or higher. An electrophotographic photoreceptor, comprising: