JPH01315750A - Photosensitive body - Google Patents

Abstract

PURPOSE:To enhance photosensitivity by adding polyvinyl acetal to a resin except polyvinyl acetal as a binder resin. CONSTITUTION:The photosensitive body is obtained by laminating on a conductive substrate 1 as a lower layer a carrier generating layer (CGL) 2 containing 100pts.wt. of a carrier generating material (CGM) and the binder resin composed of, preferably, 10-500, especially, 20-300pts.wt. of the resin other than the polyvinyl acetal, and preferably, 0.1-250, especially, 0.2-150pts.wt. of the polyvinyl acetal and as an upper layer a carrier transfer layer (CTL) 3 containing, preferably, 0-300pts.wt. of a carrier transfer material (CTM) and the binder resin composed of 100pts.wt. (independent of said 100pts.wt. of the CGM) of the resin other than the polyvinyl acetal and, preferably, 0.02-50, much preferably, 0.1-40, especially, 0.2-30pts.wt. of the polyvinyl acetal, thus permitting the obtained electrophotographic sensitive body to be enhanced in photosensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a photoreceptor, for example, an electrophotographic photoreceptor.

In the electrophotographic copying method of the prior art Carlson method, after the surface of a photoreceptor is charged, an electrostatic latent image is formed by exposure, the electrostatic latent image is developed with toner, and then the visible image is formed. Transfer and fix onto paper, etc. At the same time, the photoreceptor is cleaned of adhering toner, neutralized, and surface cleaned.
Used repeatedly over a long period of time.

Therefore, as an electrophotographic photoreceptor, it not only has electrophotographic properties such as good charging characteristics, good sensitivity, and low dark decay, but also physical properties such as stiffness resistance, abrasion resistance, and moisture resistance after repeated use. It is also required to have good properties and resistance to ozone generated during corona discharge, ultraviolet rays during exposure, etc. (environmental resistance).

Conventionally, as electrophotographic photoreceptors, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide have been widely used.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years.

For example, in Japanese Patent Publication No. 50-10496, poly-N-
vinyl carbazole and 2. 4. 7-) Dinitro-9
- An organic photoreceptor having a photosensitive layer containing fluorenone is described. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability.

In order to improve such defects, in the photosensitive layer,
Attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the functions of carrier generation and transport to different substances. In such a so-called functionally separated electrophotographic photoreceptor,
Since substances that exhibit each function can be selected from a wide range of materials, it is possible to relatively easily produce an electrophotographic photoreceptor having arbitrary characteristics. Therefore,
It is expected that organic photoreceptors with high sensitivity and durability will be obtained.

In the photosensitive layer of such an electrophotographic photoreceptor, efforts are being made to obtain an electrophotographic photoreceptor having excellent electrophotographic properties and film strength by using a carrier-generating substance and a polymer binder in combination.

At this time, the carrier-generating substance is dissolved, dispersed, etc. in the polymer binder, and the generated photocarriers are transported through the layer. Therefore, depending on the type of polymer binder, etc., the optical carrier transport ability in the layer is greatly influenced.
Therefore, the selection of a polymeric binder is an extremely important factor governing the photosensitivity of a photoreceptor. However, there is no general rule for uniform selection of binders, and the actual situation is that binders are selected based on repeated experiments, taking into account the type of carrier-generating substance, etc.

On the other hand, even if a polymeric binder is used that can provide an electrophotographic photoreceptor with excellent electrical properties, the liquid physical properties and stability of the coating liquid when forming a photosensitive layer may not be sufficient. During dip coating, the uniformity of the coating layer was microscopically insufficient, and the electrophotographic properties of the resulting electrophotographic photoreceptor were sometimes uneven.

An object of the present invention is to provide a photoreceptor that has excellent photosensitivity, has a layer containing a carrier-generating substance that has good coating properties, and is capable of producing uniform and high-quality images. .

21 Structure of the invention and its effects The present invention has a layer containing a carrier generating substance, polyvinyl acetal, and a resin other than the polyvinyl acetal, and in this layer, the resin other than the polyvinyl acetal is more than the polyvinyl acetal. This also relates to a photoreceptor in which the content is large in terms of weight ratio.

The present invention has a remarkable feature in the binder resin of the layer containing the carrier-generating substance.

That is, as the binder resin, "polyvinyl acetal" is added to "resin other than polyvinyl acetal",
It is important that both are used together.

That is, the present inventors have discovered that by adding polyvinyl acetal to a resin other than polyvinyl acetal, an unexpected improvement in photosensitivity can be seen.
Moreover, this makes it possible to create a layer containing a carrier-generating substance.
The coating properties were also improved, and high-quality images were obtained that were uniform and had little image defects (non-uniform fogging, rings of reduced blackness in solid black areas) suppressed.

Furthermore, as will be described later, it has been confirmed that the addition of a small amount of polyvinyl acetal can significantly improve the photosensitivity and the coating properties of the layer containing the carrier-generating substance, which is extremely noteworthy. Good morning.

Possible reasons for the increased sensitivity include improvements in the range probability of photocarriers, such as control of electric field effects and transport sites by controlling the junction state at the interface, and reduction of trap sites. Moreover, the reason for the high image quality is presumed to be the uniformity of the coating film due to changes in coating liquid physical properties (viscosity, flow characteristics, etc.) due to binder interaction, CGM=binder interaction, etc. However, these causes are not necessarily clear.

The photoreceptor of the present invention has a support l as shown in FIG.
(a conductive layer is provided on a conductive support or sheet), a carrier generation layer 2 (hereinafter sometimes referred to as CGL) containing a carrier generation material it (CGM) and a binder resin is formed as a lower layer, and a carrier Carrier transport layer 3 containing a transport material (CTM) and optionally a binder resin
(hereinafter sometimes referred to as CTL) as an upper layer, and a photosensitive layer with a laminated structure on a support 1 with CTL3 as a lower layer and CGL2 as an upper layer, as shown in Figure 2. 4B, as shown in FIG. 3, a photosensitive R4D with a single layer structure containing CGM, CTM, and binder resin as necessary is provided on the support 1,
For example, as shown in FIG. 4, a protective layer 5 is provided on a photosensitive layer 4B (see FIG. 2) having a laminated structure.

Further, CGL may contain both CGM and CTM, a protective layer (OCL) may be provided on the photosensitive layers 4A and 4D, and an intermediate layer or undercoat layer may be provided between the support and the photosensitive layer. It may be provided.

In the examples shown in FIGS. 1 to 4, the "layer containing a carrier-generating substance" refers to the carrier-generating layer 2 and the photosensitive layer 4D.

In the "layer containing a carrier-generating substance", when the content of CGM is 100 fEffi parts, the content of "resin other than polyvinyl acetal" is 10 to 50.

It is preferably 20 to 300 parts by weight! It is even more preferable to use 1 part by weight. Further, the content of "polyvinyl acetal" is preferably 0.1 to 250 parts by weight, more preferably 0.2 to 150 parts by weight. Similarly, the content of CTM is 0 to 500 parts by weight. The amount is preferably 0 to 300 parts by weight, and more preferably 0 to 300 parts by weight.

Furthermore, when the content of "resin other than polyvinyl acetal" in the "layer containing a carrier-generating substance" is 100 parts by weight, the content of "polyvinyl acetal" is 0.
．． Preferably L<, 0.1 to 50 parts by weight
The amount is more preferably 40 parts by weight, and even more preferably 0.2 to 30 parts by weight.

Next, polyvinyl acetal will be described.

Generally, polyvinyl acetal refers to polyvinyl alcohol obtained by saponifying polyvinyl acetate (or a partially saponified product of its ester), in which most of the hydroxyl groups are condensed with aldehyde to form an acetal.

In the acetalization reaction, polyvinyl acetate cannot be completely acetalized, so polyvinyl acetal is represented by the following general formula.

In this formula, R is H-, polyvinyl formal, R is CH, - is polyvinylacetoacecool,
Those in which R is C, H, - are called polyvinyl butyral and are well known.

Polyvinyl formal Polyvinyl formal is produced, for example, by reacting polyvinyl alcohol and formaldehyde with acidic hydrochloric acid.

In the above formula, l is 70% by weight or more, m is 10 to
20% by weight, n is preferably 3 to 10% by weight, and the average degree of polymerization is preferably 2000 or less (more preferably 1500 or less).

Polyvinyl butyral is produced, for example, by adding butyraldehyde to polyvinyl alcohol and reacting it with acidic hydrochloric acid.

In the above formula 1, l is preferably 60% by weight or more, m is preferably 10% by weight or less, and n is preferably 10 to 30% by weight. The average degree of polymerization is 4000 or less (even 3
000 or less) is preferred.

Specific product names of polyvinyl formal include "Denka Formal #20J, rDenka Formal #30",
Denka Formal #100 J, “Denka Formal #
Examples include Denka Formal series such as 200 J (manufactured by Denki Kagaku Co., Ltd.).

Specific trade names of polyvinyl butyral include Denka Butyral #2000-L, Denka Butyral #3000-1, Denka Butyral #
3000-2, #3000-4, #3000-K
, same #-4000-1, same #4000-2, same #50
00-A, #6000-C (manufactured by Denki Kagaku Kogyo Co., Ltd.), XYHL (manufactured by Union Kanibite Co., Ltd.), S-LEC BM-2, Varnish 1 F28 Varnish 1 F28 LEC BL-2, S-LEC BL-3 , S-Lec BL
-3, Nisleg BL-7, S-Lec BX-L,! Examples include SL'TSUKU BX Is-[-SUIz7ri BX-7, SLEK BH-3 (all manufactured by Block Chemical Industry Co., Ltd.), and the like.

Two or more types of polyvinyl acetal can also be used in combination.

Examples of "resins other than polyvinyl acetal" include polyethylene, polypropylene, acrylic resin, methacrylic resin, epoxy resin, polyurethane resin, polyester resin, alkyd resin, polycarbonate resin, vinyl chloride resin, silicone resin, melamine resin, methacrylic resin, and acrylic resin. Resin, polyvinylidene chloride, addition polymer resin such as polystyrene, polyaddition resin, polycondensation resin, copolymer resin containing two or more of these repeating units, styrene-butadiene copolymer resin, chloride Vinyl-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, vinylidene chloride-
Examples include one or more selected from acrylonitrile copolymer resins and polymeric organic semiconductors such as N-vinylcarbazole.

Among these, polyester resins, polycarbonate resins, acrylic resins, epoxy resins, styrene-acrylic resins, polyvinyl acetals (eg, polyvinyl butyral), phenolic resins, silicone resins, and the like are preferred.

As the carrier generating substance (CGM), any inorganic pigment or organic pigment can be used as long as it absorbs electromagnetic waves and generates free carriers. Examples of CGM include the following.

(1) Amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, mercury sulfide, lead sulfide,
Inorganic pigments such as zinc oxide and amorphous silicon (2) Azo pigments such as monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene azo and thiazole azo pigments (3) Anthraquinone derivatives, anthorone derivatives, di benzpyrenequinone derivatives, pyrantrone derivatives,
Anthraquinone or polycyclic quinone pigments such as violanthrone derivatives and isoviolanthrone derivatives (4) Indigoid pigments such as indigo derivatives and thioindigo derivatives (5) Diphenylmethane pigments, triphenylmethane pigments, xanthine pigments, acridine pigments, etc. Carbonium pigments (6) Quinoneimine pigments such as azine pigments, oxazine pigments and thiazine pigments (7) Methine pigments such as cyanine pigments and azomethine pigments (8) Quinoline pigments (9) Nitro pigments (10) Nitroso pigments (11) Benzoquinone and naphthoquinone pigments (12)
Naphthalimide pigments (13) Perylene pigments such as bisbenzimidazole derivatives (14) Fluorenone pigments (15) Squarylium pigments (16) Azulenium compounds (17) Perylene pigments such as perylene anhydride and perylene imide (18) ) Metal-free phthalocyanine pigments such as α-type, β-type, χ-type, and τ-type, metal phthalocyanine pigments such as titanyl phthalocyanine, and polycyclic bovine non-based pigments such as anthorone pigment, dibenzpyrenequinone pigment, and lanthrone pigment. Particularly preferred are pigments, azo pigments, phthalocyanine pigments, and the like.

Preferred azo pigments and polycyclic quinone pigments are illustrated below.

Exemplary compound group [I]: Exemplary compound [■]: (Hereafter the blank space) Exemplary compound group [■]: (Hereafter the blank space) Exemplary compound group [■]: Also, the exemplary compound group consisting of the following polycyclic quinone pigments (VI
) to (■) can also be used as carrier-generating substances.

Exemplary compound group [■]: Exemplary compound group [■]: Exemplary compound group [■]: In the photoreceptor as shown in FIG. The thickness of the transport layer is preferably 5 to 50 μm.

In the photoreceptor as shown in FIG. 2, the carrier generation layer preferably has a thickness of 1 to 10 μm, and the carrier transport layer preferably has a thickness of 1 to 30 μm.

In the photoreceptor shown in FIG. 3, the thickness of the photosensitive layer is preferably 5 to 30 μm.

The thickness of the undercoat layer or intermediate layer provided between the photosensitive layer and the conductive substrate, if necessary, is preferably 0.01 to 5 μm.

The thickness of the surface protective layer provided as necessary is 0.1 to 5.
μm is preferred.

The content of the carrier transport substance in the carrier transport layer is preferably 10 to 200 parts by weight per 100 parts by weight of the binder resin.

In the layer containing the carrier-generating substance, the particulate carrier-generating substance is bound in the binder resin (it may contain a carrier transporting substance if necessary), and is dispersed in the layer in the form of a dye or pigment. Preferably.

When a photosensitive layer is formed by dispersing a granular carrier-generating substance, the carrier-generating substance is in the form of powder with an average particle size of 2 μm or less, preferably 1 μm or less, and more preferably 0.5 μm or less. is preferred.

Further, in the carrier transport layer, the carrier transport substance preferably has excellent compatibility with the binder substance. This allows for a very wide mixing ratio with the binder material, resulting in a uniform and stable carrier transport layer, resulting in better sensitivity and charging characteristics. Furthermore, it is possible to use a photoreceptor that can form clear images with high sensitivity, and it is possible to achieve the effect that fatigue deterioration is less likely to occur especially during repeated use.

The "layer containing a carrier-generating substance" can be provided by the following method.

(a) A method in which a binder and a solvent are added to a carrier-generating substance and a mixed solution is applied.

(b) Use a ball mill, homomixer, or
A method of forming fine particles in a dispersion medium with or without a binder using a sand mill, ultrasonic dispersion machine, attritor, etc., and applying a dispersion obtained by mixing and dispersing with a binder added if necessary.

Dispersing the particles under the action of ultrasound in these methods allows for homogeneous dispersion.

At this time, if "polyvinyl acetal" is insoluble in the solvent in which "resin other than polyvinyl acetal" is to be dissolved, dissolve the "polyvinyl acetal" in the other solvent and then mix the solutions of each resin. good. Further, the same effect can be obtained by mixing before or after dispersion.

When a carrier transporting substance is contained in a layer containing a carrier generating substance, a method of dissolving or dispersing the carrier transporting substance in the solution (a) or the dispersion liquid of (b) above, that is, in the carrier generating layer. There is a method of adding a carrier transport substance.

Further, in the type shown in FIG. 1, there is a method in which a solution containing a carrier transport substance is applied onto the carrier generation layer, and the carrier generation layer is swollen or partially dissolved to diffuse the carrier transport substance into the carrier generation layer. When this method is adopted, it is not necessary to add a carrier transporting substance to the carrier generation layer as described above, but it is also possible to carry out the above three methods at the same time.

Further, the carrier transport layer can be formed by coating and drying the above-mentioned carrier transport substance alone or by dissolving and dispersing it together with the above-mentioned binder resin.

Examples of solvents used for forming the photosensitive layer of the present invention include hydrocarbons such as hexane, benzene, toluene, and xylene, methylene chloride, 1,2-dichloroethane, sym-tetrachloroethane, and cis-1,2-dichloroethane. Chlorethylene, 1,1゜2-trichloroethane, 1.1
．． 1-Trichloroethane, chloroform, bromoform, chlorobenzene and other halogenated hydrocarbons, acetone,
Ketones such as methyl ethyl ketone and cyclohexanone,
Esters such as ethyl acetate and butyl acetate, methanol,
Alcohols and derivatives thereof such as ethanol, propatool, butanol, cyclohexanol, pectanol, ethylene glycol, methyl cellosolve, ethyl cellosolve, acetic acid cellosolve.

Ethers such as tetrahydrofuran, 1,4-dioxane, furan and furfural, acetals, pyridine and amines 1. In addition to nitrogen compounds such as amides, fatty acids and phenols, sulfur such as carbon disulfide and triethyl phosphate,
Examples include a single solvent of any of the solvents such as a phosphorus compound, or various mixed solvents containing these as main components.

Furthermore, any of the above-mentioned solvents can be used as the solvent for "polyvinyl acetal", but in particular, ketones (
acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, methyl N-amyl ketone, cyclohexanone, isophorone, etc.), aromatics (benzene, toluene, xylene, etc.), and esters (ethyl acetate, butyl acetate, isobutyl acetate, cellosolve, etc.), and even cyclic ethers (
(THF, etc.) alone or in combination.

The photosensitive layer (layer containing a carrier-generating substance, carrier transport layer), undercoat layer, intermediate layer, protective layer, etc. can be formed by, for example, blade coating, dip coating, spray coating, roll coating, etc.
It can be provided by spiral coating or the like.

The carrier transport substances used in the present invention include carbazole derivatives, oxazole derivatives, oxadiazole derivatives,
Thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives,
imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives,
Oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, poly-N-vinylcarbazole, poly-1- vinylpyrene, poly-9
- It may be one or more selected from vinylanthracene and the like.

The general formula is listed below.

The following general formula (IX) or (X
) styryl compounds can be used.

- Formula [■]: (However, in this - formula, 9+, RZ represents a substituted or unsubstituted alkyl group, aryl group, and substituents include an alkyl group, an alkoxy group, a substituted amine group, a hydroxyl group, a halogen atom, Use an aryl group.

Ar', Ar": Represents a substituted or unsubstituted aryl group, and the substituent includes an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, and an alkyl group.

R3 and R4 represent a substituted or unsubstituted aryl group or a hydrogen atom, and as substituents, an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen ring, or an aryl group is used. ) General formula [X]: ■ S (However, in this formula, R5, substituted or unsubstituted aryl group, R&, hydrogen atom, halogen atom, substituted or unsubstituted alkyl group,
Alkoxy group, amine group, substituted amino group, hydroxyl group, R? , represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. ) In addition, the following general formula (XI), (
X11), (Xlla), (XI[b) or (XI[I
) can also be used.

-Math [x! ]: (However, in this formula, R8 and R9 each represent a hydrogen atom or a halogen atom, RIO and R": each represents a substituted or unsubstituted aryl group, Ar": represents a substituted or unsubstituted arylene group.) General Formula (XII): (In this formula, Rlt represents a substituted or unsubstituted aryl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted heterocyclic group, R'', R'4 and RIS, representing a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group) (However, in this formula, R'': methyl group, ethyl group, 2 -Hydroxyethyl group or 2-chloroethyl group, R17: Methyl group, ethyl group, benzyl group or phenyl group, RIS, methyl group, ethyl group, benzyl group or phenyl group.

General formula [xUb]: (In this formula, Rlt is a substituted or unsubstituted naphthyl group; R20 is a substituted or unsubstituted alkyl group,
an aralkyl group or an aryl group; R11 is a hydrogen atom, an alkyl group, or an alkoxy group; Rzz and RZ3 are the same or different groups consisting of a substituted or unsubstituted alkyl group, an aralkyl group, or an aryl group; ) -Formula (XII[): (However, in this formula, R24: Substituted or unsubstituted aryl group R2S, hydrogen atom, substituted or unsubstituted alkyl group, or substituted or device-substituted aryl group, Q: Hydrogen atom , halogen atom, alkyl group, substituted amino group, alkoxy group or cyano group, s: O or an integer of 1.) In addition, as a carrier transport substance, the following general formula (XIV)
pyrazoline compounds can also be used.

- Formula (XrV): [However, in this formula, l: O or 1, R2h and R17: substituted or unsubstituted aryl group, R■: substituted or unsubstituted aryl group, R group, or heterocyclic group, RZ! and R2@ dihydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group or aralkyl group (however, R" and R"' are not both hydrogen atoms, and the above l When is O, R29 is not a hydrogen atom.) Furthermore, an amine derivative of the following general formula (XV) can also be used as a carrier transport substance.

- Formula (XV): (In this formula, Ar', Ar': represents a substituted or unsubstituted phenyl group, and a halogen atom, an alkyl group, a nitro group, or an alkoxy group is used as a substituent.

Ar”: Represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, fluorenyl group, or heterocyclic group, and substituents include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an aryloxy group, an aryl group, and an amino group. , a nitro group, a piperidino group, a morpholino group, a naphthyl group, an anthryl group, and a substituted amino group. However, an acyl group, alkyl group, aryl group, or aralkyl group is used as a substituent for the substituted amino group.) Furthermore, the following Compounds of general formula (XVI) can also be used as carrier transport substances.

General formula (XVI): (However, in this formula, Ar': represents a substituted or unsubstituted arylene group, Roll, R2Z, R33 and R34: substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group , or represents a substituted or unsubstituted aralkyl group) Furthermore, a compound of the following general formula [X■] can also be used as a carrier transport substance.

General formula [X■]: [However, in this formula, R3S, R3h, R3? and R31' are hydrogen, an atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, a benzyl group, or an aralkyl group, R39 and R4, respectively.
6 is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, or an aralkyl group (provided that Ro and R4e' jointly Number of carbon atoms: 3~
Ten saturated or unsaturated hydrocarbon rings may be formed. ) R'1% R", R4 and R" each represent a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, ° It is an amino group, an alkylamino group, or an arylamino group. ] An antioxidant can be contained in the carrier transport layer, carrier generation layer, and photosensitive layer. This can suppress the influence of ozone generated during discharge, and can prevent an increase in residual potential and a decrease in charged potential during repeated use.

Examples of the antioxidant include hindered phenol, hindered amine, paraphenylene diamine, aryl alkane, hydroquinone, spirochroman, spiroindanone and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, and the like.

These specific compounds are disclosed in Japanese Patent Application No. 61-1628.
No. 66, No. 61-188975, No. 61-19587
No. 8, No. 61-157644, No. 61-195879
No. 61-162867, No. 61-204469, No. 61-217493, No. 61-217492, and No. 61-221541.

A polymeric organic semiconductor can also be included in the photosensitive layer. Among these polymeric organic semiconductors, poly-N-vinylcarbazole or its derivatives are highly effective and are preferably used. Such poly-N-vinylcarbazole derivatives mean that all or part of the carbazole ring in the repeating unit has various substituents, such as an alkyl group,
Substituted with a nitro group, an amino group, a hydroxy group, or a halogen atom.

Furthermore, at least one type of electron-accepting substance can be contained in the photosensitive layer for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, and the like.

Electron-accepting substances that can be used in the photoreceptor of the present invention include:
For example, succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4
-Nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, 0-dinitrobenzene, m-dinitrobenzene,
1.3.5-Trinitrobenzene, varanitrobenzonitrile, vicryl chloride, quinone chlorimide, chloranil, pullmanil, 2-methylnaphthoquinone, dichlorodicyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-fluorenylide - [dicyanomethylene malonodinitrile], polynitro-9-fluorenylidene [dicyanomethylene malonodinitrile], picric acid, 0-nitrobenzoic acid, p-nitrobenzoic acid, 3.5-dinitrobenzoic acid, pentafluoro Benzoic acid, 5-nitrosalicylic acid,
3,5-dinitrosalicylic acid, phthalic acid, mellitic acid,
One or more types of other compounds with high electron affinity can be mentioned. Among these, fluorenone series, quinone series, and benzene derivatives having electron-withdrawing substituents such as C1%CN and No.1 are particularly preferred.

Furthermore, a silicone oil or a fluorocarbon surfactant may be present as a surface modifier. Further, an ammonium compound may be contained as a durability improver.

Furthermore, an ultraviolet absorber may be used. Preferred ultraviolet absorbers include nitrogen-containing compounds such as benzoic acid, stilbene compounds and derivatives thereof, triazole compounds, imidazole compounds, triazine compounds, coumarin compounds, oxadiazole compounds, thiazole compounds and derivatives thereof.

The various binder resins described above can be used in the carrier transport layer.

In addition, for the subbing layer or intermediate layer provided as necessary,
In addition to the above binder resins, for example, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, casein, N-alkoxymethylated nylon, starch, etc. can be used.

As a binder for the protective layer provided as necessary,
Volume resistance 10”Ω・cat or more, preferably 1010Ω
A transparent resin having a Cl11 or more, more preferably an IQ of 13Ω'cat or more is used.The binder may also be a resin that is cured by light or heat, and examples of the resin that is cured by light or heat include, for example, a thermosetting resin. Acrylic resin, silicone resin, epoxy resin, urethane resin,
Urea resins, polyester resins, alkyd resins, melamine resins, photocurable cinnamic acid resins, etc., or copolymerized or condensed resins thereof, and all other photo- or thermosetting resins used in electrophotographic materials can be used. . If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Such thermoplastic resins include, for example, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polycarbonate resin, silicone resin, or copolymer resins thereof, such as vinyl chloride-vinyl acetate-maleic anhydride resin. , polymeric organic semiconductors such as poly-N-vinylcarbazole, and other thermoplastic resins used in electrophotographic materials can all be used.

The conductive substrate is a metal plate, a metal drum or a conductive polymer,
Applying a conductive thin film made of a conductive compound such as indium oxide or a metal such as aluminum, palladium, or gold,
Those provided on a substrate such as paper or plastic film by means such as vapor deposition or lamination are used.

E. Examples The present invention will be described in detail below, but the embodiments of the present invention are not limited thereby.

[Experiment■]

Niwa Yuusei Insect Disaster External Diameter 8. On the aluminum substrate of Ota mφ, vinyl chloride-vinyl acetate-maleic acid copolymer
Made of F-10J (manufactured by Block Chemical Industry Co., Ltd.), thickness approximately 0.
．． An intermediate layer of I IIm was provided.

Next, 100 parts by weight of CGM (1) shown in FIG.
A solution prepared by dissolving a predetermined amount of "binder resin other than polyvinyl acetal" in 4,170 parts by weight of 1,2-dichloroethane was added, and further dispersed for 24 hours using a ball mill. A predetermined amount of a solution of "polyvinyl acetal" dissolved in a predetermined solvent as shown in FIG. Sa1
A μ-CGL was formed. The content of "polyvinyl acetal" is expressed as solid content.

Next, 75 parts by weight of the following CTM (1) and 1 part of polycarbonate "Nipilon Z-200J (manufactured by Mitsubishi Gas Chemical Industries, Ltd.)
00 parts by weight and 1.00 parts by weight.・Dissolved in 625 parts by weight of 2-dichloroethane, applied the resulting solution by dip coating onto the carrier generation layer, dried at a temperature of 80°C for 1 hour, and formed a 20 μm thick C
TL was formed.

“Resin other than polyvinyl acetal” Polycarbonate resin: “Panlite L-1250J (
(manufactured by Kijin Kasei Co., Ltd.) Polyester resin = "Vylon 200" (manufactured by Toyobo Co., Ltd.) Acrylic resin: [Acrivet #001 J (manufactured by Mitsubishi Rayon Co., Ltd.) Epoxy resin = [Epicoat 1001 J (manufactured by Yuka Shell Epoxy Co., Ltd.) Polyvinyl butyral: "S-LEC BL-IJ (manufactured by Blockbuster Chemical Industry Co., Ltd.) Acetyl group 3 mo1% or less Butyral group 63 ± 3 #01% 7 "Denka Butyral #3000-Kl (manufactured by Denki Kagaku Kogyo Co., Ltd.) Composition: Polyvinyl acetate component 2.0 ~8.4Wt
χ Polyvinyl alcohol component 9-13 Each photoreceptor shown in FIG. 5 was prepared.

(2) For each electrophotographic photoreceptor obtained in the above manner, a voltage of +6 KV was applied to the charging electrode using an electrostatic charging tester rEPA-8100J (manufactured by Kawaguchi Denki Seisakusho Co., Ltd.).
The photosensitive layer was charged by corona discharge for seconds.

After that, it was left for 5 seconds (the potential at this time is called the initial potential), and then the light intensity on the surface of the photosensitive layer decreased to 21u.
Exposure amount E required to attenuate the initial potential from -600 m to -too v by irradiating light from a halogen lamp in a state where x is ? ? ! (j!ux-sec) was measured.

Further, Sλ was measured at a wavelength λ'' of 540 nm using a spectrometer MC-20L (manufactured by Ritsuichi Applied Optics Co., Ltd.).

However, Sλ is 0.5 μW/cm for light with a specific wavelength λ.
Vo = -800V to V = -10 when irradiated with
This is the amount of potential attenuation per unit energy during attenuation to 0V. In FIG. 5, the values are expressed as relative values when the value of Sλ for the photoreceptors of each comparative example is set to 1.00. That is, photoreceptor 1-AS! -BS 1-F
, I-G, the value of Sλ of photoreceptor 1-a is 1.0.
For photoreceptor I-C, the relative value when the value of Sλ of photoreceptor 1-c is taken as 1.00, for photoreceptor ID, the relative value when the value of Sλ of photoreceptor r-d is taken as 1.00. value 1.00
Relative value when photoreceptor 1-H is photoreceptor 1
- As a relative value when the value of Sλ of e is 1.00,
Each is a representation.

Furthermore, it was installed on a modified U-Bix 1550 MR (manufactured by Konica), and the black paper potential ■ゎ, the white paper potential v, 1, and the residual potential ■
The initial value of , and the respective variation amount ΔV after 10,000 copies
,,Δv1. l, Δv7 were measured. That is, A Vb
= l Vll 10,000': l '' - 1 - IVb initial value 1, and the others are the same.

The black paper potential here refers to the surface potential of the photoreceptor when the above-mentioned copying cycle is performed using a black paper original with a reflection density of 1.3, and the white paper potential refers to the surface potential of the photoreceptor when a blank paper is used as the original. Represents the surface potential of the body.

The results of these measurements are shown in FIG.

[Experiment■]

An intermediate layer was formed in the same manner as in Experiment (2).

Next, CGM (II) shown in FIG. 6 was added to a solution in which a predetermined amount of resin other than the polyvinyl acetal shown in FIG. 6 was dissolved in 10,500 parts by weight of 1,2-dichloroethane.
100 parts by weight was added and dispersed using a sand grinder for 8 hours. Into this dispersion, a solution of "polyvinyl acetal" shown in Fig. 6 dissolved in a predetermined solvent was added in a predetermined amount (
The liquid obtained by mixing (represented in the figure in terms of solid content) was dip-coated onto the intermediate layer to form a CGL having a thickness of 0.4 μm.

Next, in Experiment I, CTM (+) was changed to the following CTM (
II) and do the same except for C with a thickness of 20 μm.
TL was formed.

In this way, photoreceptors 11-A and UB of experimental examples and photoreceptors 11-a of comparative examples were prepared.

For each of these electrophotographic photoreceptors, measurements similar to those in Experiment (2) were performed. However, for Sλ, the value of -a is set to 1.
It is expressed as a relative value when it is set to 00.

The results are shown in FIG.

[Experiment■]

An intermediate layer was formed in the same manner as in Experiment (2).

Next, to 100 parts by weight of CGM (I [I) shown in FIG. 6, a predetermined amount of "Zubinder resin other than polyvinyl acetal" shown in FIG.
The solution dissolved in parts by weight was added and dispersed using a sand grinder for 5 hours. A solution of "polyvinyl acetal" shown in FIG. 6 dissolved in a predetermined solvent is mixed into the obtained dispersion liquid, and a solution containing a predetermined amount of "polyvinyl acetal" as a solid component is placed on the intermediate layer. It was applied by dip coating and sufficiently dried to form a CGL with a thickness of 0.4 μm.

Next, in experiment ①, CTM (I) was changed to the following CTM
(I [I), except for the same procedure, thickness 20 μm
CTLs were formed.

Electrophotographic photoreceptor I [[
-A, the same measurements as in Experiment I were performed on the photoreceptor m-a of Comparative Example. The results are shown in FIG. However, regarding Sλ, for photoconductor ■-A, photoconductor m
The values are shown when the value of Sλ of -a is 1.00.

CGM (I[I) τ-type metal-free phthalocyanine CTM ([1) [Experiment■] An intermediate layer was formed in the same manner as in Experiment I.

Next, change the CGM (I [I) of experiment ■ to CGM (IV)
A carrier generation layer and a carrier transport layer were sequentially coated and formed on the intermediate layer in the same manner as in Experiment ① except that .

Electrophotographic photoreceptor IV- of the example thus produced
A. Regarding the photoreceptor IV-a of Comparative Example, the same measurements as in Experiment ① were carried out. However, regarding Sλ, photoreceptor IV-
For A, the value of Sλ of photoreceptor IV-a is set to 1. It is expressed as a relative value when OO. The results are shown in FIG.

CGM (IV) X-type metal-free phthalocyanine [Experiment■] An intermediate layer similar to Experiment ① was provided.

Next, 75 parts by weight of the CTM (n) and 1 part of polycarbonate "Panrai" K-1300J (manufactured by Kijin Kasei Co., Ltd.)
00 parts by weight and 1.00 parts by weight. Dissolved in 760 parts by weight of 2-dichloroethane and dip coated the resulting solution on the intermediate layer,
It was dried at a temperature of 80° C. for 1 hour to form a CTL with a thickness of 20 μm.

Next, 50 parts by weight of CGM (1) shown in FIG. 6 was ground in a ball mill for 24 hours, and a predetermined amount of "binder resin other than polyvinyl acetal" shown in FIG.
A solution dissolved in 1750 parts by weight of 2-dichloroethane was added and further dispersed in a ball mill for 24 hours. To this dispersion, 75 parts by weight of CTM (II) was added, and further 750 parts by weight of monochlorobenzene and a solution of "polyvinyl acetal" shown in FIG.
In the report, it is expressed as solid content. ) was added to prepare a coating solution.

This coating solution was spray coated onto the carrier transport layer to obtain a carrier generation layer having a thickness of 5 μm.

Electrophotographic photoreceptor V-A of the example thus produced
The same measurements as in Experiment I were performed on the photoconductor Va of Comparative Example. However, regarding the value of Sλ, the photoreceptor V-A
is expressed as a relative value when the value of Sλ of photoreceptor Va is 1.00.

The results are shown in FIG.

[Experiment■]

In experiment ①, photoreceptor 1-A Nr-E and ①-a~
Regarding I-e, each photoreceptor Vl-A ~
Vl-E and VI-a to Vl-e were created. Then, the same measurements as in Experiment I were performed for each photoreceptor. The results are shown in FIG.

Polyvinyl formal: "Denka formal #100 J (manufactured by Denki Kagaku Kogyo Co., Ltd.) Composition: Polyvinyl acetate component 9 to 12 Wt! Polyvinyl alcohol component 5 to 6 Wtχ Polyvinyl formal component 82 W t% or more Average degree of polymerization: Approx. 750" Denka Formal #20J (manufactured by Denki Kagaku Kogyo Co., Ltd.) Composition: Polyvinyl acetate component 9 to 13 WtX Polyvinyl alcohol component 5.5 to 8.5 Wtχ Polyvinyl formal component 78% or more Average degree of polymerization: Approximately 450 [Experiment ■ ] Photoreceptor II of Experiment ■ As II 8% If-a
For each photoreceptor ■-A, ■-B, the same procedure as in experiment ■ was carried out by replacing polyvinyl butyral with polyvinyl formal.
, ■-a were created. Then, measurements similar to those in Experiment (2) were performed on each photoreceptor. The results are shown in FIG.

[Experiment■]

Photoreceptors ■-A and ■-a were prepared in the same manner as in Experiment (2) except that polyvinyl butyral was replaced with polyvinyl formal for Photoreceptor (2)-A1 (2)-a of Experiment (2). Then, measurements similar to those in Experiment (2) were performed on each photoreceptor. The results are shown in FIG.

[Experiment■]

Regarding the photoreceptors IX-A and IX-a of Experiment 2, polyvinyl butyral was replaced with polyvinyl formal, and Experiment 2 was carried out.
Photoreceptors IX-A and IX-a were prepared in the same manner. Then, the same measurements as in Experiment I were performed for each photoreceptor.

The results are shown in Figure 8.

[Experiment X]

Regarding the photoreceptors V-A and V-a of Experiment (2), each photoreceptor (X A % X-a) was prepared in the same manner as in Experiment (2) except that polyvinyl butyral was replaced with polyvinyl formal. Then, measurements similar to those in Experiment (2) were performed on each photoreceptor.
The results are shown in FIG.

As is clear from the above experimental results, the photoreceptor of the example has good photosensitivity and is particularly excellent in white paper potential (L).

[Experiment XI] Using the photoreceptor formulation described in Experiment I, the following experiment was conducted.

That is, in the same manner as described in Experiment I, an electrophotographic photoreceptor was prepared having a carrier generation layer containing 50 parts by weight of polycarbonate resin, polyvinyl acetals (1), (2), O, and 100 parts by weight of CGM (1).

However, in the example, the same polycarbonate resin was further added to 50 parts by weight of the polycarbonate 4M resin.

The content of polyvinyl acetal in polycarbonate resin (see FIG. 9) (value calculated based on 100 parts by weight of polycarbonate resin) was varied. In addition, for the intermediate layer and carrier transport layer, Experiment I
The same is true. However, in the comparative example, the amount of the polycarbonate resin itself was increased by the amount shown on the horizontal axis in FIG.

Sλ was measured for each photoreceptor produced in this manner. However, the value of Sλ was a relative value when the value of Sλ when the content ratio of the vinyl chloride resin was 0 parts by weight was set to 1.00.

The results are shown in FIG.

[Coating liquid physical properties, coating film evaluation]

The viscosity of each coating solution for the carrier generation layer and active layer of the electrophotographic photoreceptor of the above-mentioned Examples and Comparative Examples was measured 1 minute after the start of measurement using an E-type viscometer (5RRM) (liquid temperature 25°C). I asked for it. As a result, a value of 50 to 60 cp was obtained for the coating liquid used in the photoreceptor of the comparative example, and a value of 10 cp or less was obtained for the coating liquid used in the photoreceptor of the example. Therefore, it can be seen that the viscosity of the coating liquid is significantly reduced by adding a small amount of resin other than polyvinyl acetal resin.

Further, the coating liquid used for the photoreceptor in the comparative example exhibits the behavior of a pseudoplastic fluid, but in the example, it exhibits behavior close to that of a Newtonian fluid.

Further, visual sensory tests were conducted on the coating films of the carrier generation layer and the single-layer photosensitive layer, and it was found that the coating films of Examples had gloss and excellent uniformity.

Note that although the resin used for the intermediate layer was vinyl chloride-vinyl acetate-maleic acid resin, the effects of each of the above-mentioned examples were obtained even if other resins were used or even if there was no intermediate layer.

[Brief explanation of the drawing]

1, 2, 3, and 4 are cross-sectional views of each side of the photoreceptor. FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are graphs showing the relationship between the structure and prescription of the electrophotographic photoreceptor and the electrophotographic characteristics, respectively. FIG. 9 is a graph showing the relationship between the amount of potential attenuation per unit energy during light irradiation and the amount of polyvinyl acetal added in the carrier generation layer. In addition, in the symbols shown in the drawings, 1--1~----- Conductive support 2-----
--One charge generation layer (CGL) 3---------...
Charge transport layer (CTL) 4 A, 4 B, 4 I)
−−−−−・−−−One photosensitive layer 5−−−−−−・・−
This is the surface (protective) layer (OCL). Agent: Patent Attorney Hiroshi AisakaFigure 1Figure 2Figure 3

Claims (1)

[Claims] 1. A photoreceptor having a layer containing a carrier-generating substance, polyvinyl acetal, and a resin other than polyvinyl acetal, and in which the resin other than the polyvinyl acetal is contained in a larger amount by weight than the polyvinyl acetal. .