JP2847828B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member using a polymer charge transfer material having a hydrazone group, and more particularly, to a method using a charge generation material and a charge transfer material. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member including a polystyrene-based compound which is a polymer charge transfer material having a hydrazone group as a charge transfer material and one or more low-molecular charge transfer materials.

[Prior art and its problems] Conventionally, selenium (Se), cadmium sulfide (Cd
S), zinc oxide (ZnO), amorphous silicon (a-S
i) and other inorganic substances. While these inorganic photoreceptors have many advantages, they also have various disadvantages such as harmfulness and high cost. For this reason, in recent years, many organic photoreceptors using organic substances having no such defects have been proposed and put to practical use.

Further, the structure of these photoconductors includes a material that generates charge carriers (hereinafter, referred to as a charge generation material) and a material that receives and moves the generated charge carriers (hereinafter, referred to as a charge transfer material). ) And a single-layer structure having a single-layer type photoconductor in which charge carrier generation and charge transfer are performed using the same material, and a multilayer structure is more preferable. It is widely used because of its wide selection of materials and high sensitivity.

In recent years, with the development of non-impact printing technology, research and development of electrophotographic printers using a laser light source have been actively conducted. In these devices,
As the device size is reduced and the operation speed is increased, it is desired that the sensitivity of the charge generation material and the mobility of the charge transfer material be increased for photosensitive materials.

In the case of a charge transfer material, it is known that the mobility greatly depends on the concentration of the transfer material (for example, triphenylamine compounds) in a binder (for example, polycarbonate) (Takahashi, Sorin, Yokoyama, electrophotography). , 25 , 16
(1986)). When the concentration of the moving material is increased, the mobility is increased, but the physical properties are deteriorated, for example, cracks are caused. Further, when the paper passes during printing, mechanical wear becomes severe. Therefore, it is difficult to add the charge transfer material to the binder (binder resin) at a high concentration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional circumstances. By blending a polymer charge transfer material with one or more low-molecular charge transfer materials, there is no decrease in mechanical strength and high mobility. It is an object of the present invention to provide an electrophotographic photoreceptor containing a charge transfer material that provides the following.

[Means for Solving the Problems] As a result of continuing research in view of such a conventional situation, the present inventors have found that a polymer having a charge-transfer functional group and one or more low-molecular-weight charge-transfer materials have been developed. It has been found that by blending, high mobility can be achieved without using high concentrations of low molecular charge transfer materials.

That is, the present invention relates to an electrophotographic photoreceptor containing a charge generation material and a charge transfer material, wherein the general formula [I]; (In the formula, R represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxyl group or a dialkylamino group, m and n are each a positive integer, and m / n is 100 or less.) An electrophotographic photosensitive member comprising, as charge transfer materials, a polymer charge transfer material having a hydrazone group having a molecular weight of 1,000 to 500,000 and having at least one kind of low molecular charge transfer materials.

The polymer charge transfer material used in the present invention is represented by the above general formula [I], and specific examples include those shown in Table 1, but similar compounds are effective. It is not limited to these.

The polymer charge transfer material represented by the general formula [I] is
General formula [II]; (In the formula, R represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxyl group or a dialkylamino group.) A hydrazone group-containing styrene compound represented by the following general formula [III]: Can be produced by copolymerizing a styrene monomer represented by the following formula at an appropriate ratio.

For example, as a first production method, first, a Grignard reagent of 4-chlorostyrene is produced, and then dimethylformamide (DMF) is added to produce 4-formylstyrene (JWDale, L. Starr and CWStrobel, J. Am. Org.C
hem., 26 , 1965, 2225). Next, a desired 1,1-diarylhydrazine compound is added to 4-formylstyrene, and the mixture is condensed in the presence of an acidic catalyst to produce a hydrazone group-containing styrene compound represented by the general formula [II]. This monomer and the styrene monomer represented by the general formula [III] are mixed at an appropriate ratio and, if necessary, are copolymerized with a polymerization initiator, whereby the polymer charge transfer polymer used in the present invention is obtained. The material is obtained.

In the second method, after protecting the aldehyde group of 4-formylstyrene produced as described above as an acetal, the compound and styrene are polymerized in the presence of a suitable polymerization initiator, and then acidified. The 4-formylstyrene-based copolymer is produced by removing the acetal group by hydrolysis in a solution. Next, the polymer charge transfer material of the present invention can be obtained also by reacting the copolymer with a hydrazine compound.

In the present invention, the polymer charge transfer material represented by the general formula [I] is easily soluble in solvents such as chloroform, methylene chloride and tetrahydrofuran, and is insoluble in methanol and ethanol.

As the low molecular charge transfer material, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N, N−
Diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N,
N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 2-methyl-4-dibenzylaminobenzaldehyde-1′-ethyl- 1'-benzothiazolylhydrazone, 2-methyl-4-dibenzylaminobenzaldehyde-1'-propyl-1'-benzothiazolylhydrazone, 2-methyl-4-dibenzylaminobenzaldehyde-1 ', 1' -Diphenylhydrazone, 9-ethylcarbazole-3-carboxaldehyde-1'-methyl-1 '
-Phenylhydrazone, 1-benzyl-1,2,3,4-tetrahydroquinoline-6-carboxaldehyde-1 ', 1'
-Diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p-
Hydrazones such as diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p- Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- (quinoline (2))-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- (pyridyl (2)) -3- (p-Diethylaminostyryl) -5- (p-diethylaminophenyl)
Pyrazoline, 1- (6-methoxy-pyridyl (2))-3
-(P-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- (pyridyl (3))
-3- (p-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- (pyridyl (2))-3- (p-diethylaminostyryl) -4-
Methyl-5- (p-diethylaminophenyl) pyrazoline, 1- (pyridyl (2))-3- (α-methyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3- (P-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) -6-pyrazoline , Pyrazolines such as spiropyrazoline, 2- (p-diethylaminostyryl) -6-diethylaminobenzoxazole, 2
Oxazole compounds such as-(p-diethylaminophenyl) -4- (p-diethylaminophenyl) -5- (2-chlorophenyl) oxazole and thiazole compounds such as 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole , Triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) -phenylmethane, 1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,2, Polyarylalkanes such as 2-tetrakis (4-N, N-dimethylamino-2-methylphenyl) ethane; stilbene-based compounds such as 1,1-diphenyl-p-diphenylaminoethylene; and 4,4'-3- Triarylamino compounds such as methylphenylphenylaminobiphenyl and the like are used.

The electrophotographic photoreceptor of the present invention is preferably formed by laminating an undercoat layer, a charge generation layer and a charge transfer layer in this order on a conductive substrate, but in the order of the undercoat layer, the charge transfer layer and the charge generation layer. A laminate may be used, or a charge generating agent and a charge transfer agent may be dispersedly coated on a subbing layer with an appropriate resin. Further, these undercoat layers can be omitted as necessary.

When the charge transfer layer and the charge generation layer have a function-separated structure, the charge transfer layer is to produce a hard film by casting a solution in which a high-molecular charge transfer material and a low-molecular charge transfer material are dissolved as described above. And is extremely useful as a charge transfer layer of an electrophotographic photosensitive member.

The amount of the polymer charge transfer material contained in the charge transfer material of the charge transfer layer is suitably 100% by weight or less, preferably about 50% by weight.

The charge transfer material contained in the charge transfer layer is 100
% Or less, and preferably 100% by weight, but a binder resin may be added as needed. These resins may be used alone or in combination of two or more.

As the electrically insulating binder (binder resin) to be contained in the charge transfer layer, phenol resin, urea resin,
Examples include melamine resin, epoxy resin, silicon resin, vinyl chloride-vinyl acetate copolymer, butyral resin, xylene resin, urethane resin, acrylic resin, polycarbonate resin, polyacrylate resin, saturated polyester resin, and phenoxy resin.

The solvent for dissolving the charge transfer material and the binder resin varies depending on the type of the resin and the like, and is preferably selected from those which do not affect the charge generation layer or the undercoat layer described later during coating. Specifically, aromatic hydrocarbons such as benzene, xylene, ligroin, monochlorobenzene and dichlorobenzene, ketones such as acetone, methyl ethyl ketone and cyclohexanone, alcohols such as methanol, ethanol and isopropanol, ethyl acetate, methyl cellosolve and the like Esters of carbon, aliphatic halogenated hydrocarbons such as carbon tetrachloride, chloroform, dichloromethane, dichloroethane, and trichloroethylene; ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether; N, N-dimethylformamide, N, N- Amides such as dimethylacetamide and sulfoxides such as dimethylsulfoxide are used. The thickness of the charge transfer layer of the electrophotographic photoreceptor
10 to 25 μm is preferred.

Furthermore, it is effective to appropriately prevent the deterioration of the charge transfer layer by appropriately adding various commonly used additives such as an ultraviolet absorber and an antioxidant.

As the conductive substrate used in the present invention, a plastic film provided with a thin layer of aluminum, nickel, chromium or the like, paper or a plastic film coated or impregnated with a conductive substance, or the like is used.

As the charge generation layer, a known photoconductive material, for example, S
e, CdS, inorganic materials such as ZnO or phthalocyanines having metal atoms such as Cu, Al, In, Ti, Pb, and V, and organic materials such as inorganic phthalocyanines, azo pigments, bisazo pigments, and cyanine pigments. The materials can be used alone or as a mixture.

Examples of the electrically insulating binder (binder resin) contained in the charge generation layer include phenol resin, urea resin, melamine resin, epoxy resin, silicon resin, vinyl chloride-vinyl acetate copolymer, butyral resin, Kirylene resin, urethane resin, acrylic resin, polycarbonate resin, polyacrylate resin, saturated polyester resin,
Phenoxy resins and the like can be mentioned. The ratio of the charge generation material contained in the charge generation layer is 0.05 to
90% by weight, preferably 30-65% by weight, is suitable.

Further, the solvent for dissolving these resins differs depending on the type of the resin, and it is desirable to select a solvent that does not dissolve the undercoat layer described below. Specific organic solvents include alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone and cyclohexane, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, tetrahydrofuran, dioxane Ethers such as ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, and trichloroethylene; or benzene, toluene, xylene, and monodiethylene. Chlorobenzene,
Aromatic compounds such as dichlorobenzene can be used.

At this time, the thickness of the charge generation layer is about 0.1 to 0.5 μm in order to maintain chargeability and ensure stability. If necessary, a plasticizer or the like can be used together with the binder. Coating can be performed using a coating method such as a dip coating method, a spray coating method, a wire bar coating method, a blade coating method, and a roller coating method.

In addition to these layers, a subbing layer can be provided on the conductive substrate for the purpose of preventing a decrease in chargeability and improving adhesion. Examples of the binder used for the undercoat layer include alcohol-soluble polyamides such as nylon 6, nylon 66, nylon 11, nylon 610, copolymerized nylon, and alkoxymethylated nylon, casein, polyvinyl alcohol,
Nitrocellulose, ethylene-acrylic acid copolymer,
Gelatin, polyurethane, polyvinyl butyral and the like are used. The undercoat layer can be formed by a method similar to that of the charge generation layer described above. At this time, the thickness of the undercoat layer is preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm. These undercoat layers can be omitted as necessary.

The electrophotographic photosensitive member of the present invention can be applied not only to a laser beam printer, but also to various other optical storage devices using a light source having a wavelength of 750 to 850 nm, such as a semiconductor laser.

Hereinafter, the present invention will be described specifically, but the present invention is not limited to the following examples unless it exceeds the gist.

[Examples] Hereinafter, examples of the present invention will be described in detail.

Production Example 1 In this Production Example, a polystyrene-based compound represented by the formula (3) was produced by a method represented by the following series of reaction formulas.

Production of Compound (1) In a flask, 14.7 g of metallic magnesium, 20 ml of ethyl ether and a small amount of ethyl bromide were added, and the mixture was heated to activate magnesium. Further, a solution of 81.8 g of 4-chlorostyrene / 400 ml of tetrahydrofuran (THF) was added to 3
Added over time. During the reaction, heat was generated and the temperature became high. Therefore, the reaction solution was cooled in a water bath and kept at 50 ° C. or lower.
After completion of the dropwise addition, the reaction was continued at room temperature for another 2 hours. 43.8 g of dimethylformamide (DMF) was added dropwise over 2 hours,
Further, it was left overnight at room temperature. 500 ml of ethyl ether was added, and the reaction solution was added to a dilute aqueous hydrochloric acid solution. Perform the extraction,
The ether layer was washed with pure water and dried over magnesium sulfate. After distilling ether, it was distilled to produce 4-formylstyrene (boiling point 70 ° C./0.8 mmHg). The yield was 42 g (63%).

Production of Compound (2) 66 g of the compound (1) produced by the above method, 92.5 g of 1,1-diphenylhydrazine, 300 ml of benzene, and a small amount of p-toluenesulfonic acid were attached to a Dean Starck receiver.
A 500 ml flask was charged, heated and refluxed for 2 hours. After completion of the reaction, benzene was distilled off and recrystallized from methanol to obtain a pale yellow solid compound (2) having a melting point of 79 ° C.

Production of Compound (3) 15 g of Compound (2), 5 g of styrene and 15 ml of benzene were charged into a 50 ml flask, and 0.5 g of azobisisobutyronitrile (AIBN) was further added. After polymerization at 60 ° C. for 24 hours, the polymerization solution was poured into a large amount of methanol. The obtained solid was dried at 50 ° C. under reduced pressure. Compound (3) with a yield of 17.5 g, a weight average molecular weight of 180,000 and a number average molecular weight of 84,000
I got

Production Example 2 In this Production Example, a method represented by the following reaction formula was used.
A polystyrene-based compound represented by the formula (3) was produced.

In a 100 ml flask, 5 g of poly (p-formylstyrene-costyrene) (compound (4)), 15 g of 1,1-diphenylhydrazine, 50 ml of tetrahydrofuran (THF) and 0.05 g of p-toluenesulfonic acid are charged, and the mixture is kept at room temperature for 4 hours The reaction was performed. After completion of the reaction, tetrahydrofuran was distilled off under reduced pressure, 50 ml of benzene was added, and the solution was treated with 50 ml of methanol.
Charged to 0 ml. The obtained solid product was filtered and then dried to produce a compound (3). The yield was 12.3 g.

Example 1 An undercoat layer made of nylon was formed on an Al substrate, and a butyral film (0.1 mm thick) containing phthalocyanine was applied as a charge generation layer on the undercoat layer. On this charge generation layer, a polymer charge transfer material (polystyrene compound obtained in Production Example 2, m / n = 1) / low molecular charge transfer material (p-diethylaminobenzaldehyde-N, N-diphenylhydrazone) / methylene chloride (1: 1: 2 weight ratio)
It was baked at 0 ° C. for 30 minutes to form a 15 μm thick charge transfer layer.

After applying a surface potential of -1100 V with a -5 kV corona discharge using an electrostatic copying tester, irradiate the light with an illuminance of 5 lux, and wait until the surface potential becomes 1/2 (seconds). Was obtained to obtain a half-life exposure amount E _1/2 (looks / second). As a result, V ₃ = −980 V and E _1/2 = 0.90 lux · sec, indicating high sensitivity. The mechanical properties were also very good.

FIG. 1 is a schematic sectional view of a photoreceptor manufactured in the present embodiment. In the figure, reference numeral 1 denotes an Al substrate, 2 denotes a charge generation layer, 3 denotes a charge transfer layer, and 4 denotes an undercoat layer.

[Effects of the Invention] As described above, according to the present invention, by blending a polymer charge transfer material with one or more kinds of low molecular charge transfer materials, a charge giving a high mobility without a decrease in mechanical strength. An electrophotographic photoreceptor containing the transfer material is obtained.

[Brief description of the drawings]

 FIG. 1 is a schematic sectional view of one embodiment of the present invention. 1 ... Al substrate, 2 ... Charge generation layer 3 ... Charge transfer layer, 4 ... Undercoat layer

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-50555 (JP, A) JP-A-3-109406 (JP, A) JP-A-2-272006 (JP, A) JP-A-2-27 107607 (JP, A) JP-A-61-20953 (JP, A) JP-A-61-296358 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5 / 00-5 / 16 CAS ONLINE

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor containing a charge generating material and a charge transfer material, wherein the general formula [I]: (In the formula, R represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxyl group or a dialkylamino group, m and n are each a positive integer, and m / n is 100 or less.) An electrophotographic photoreceptor comprising, as charge transfer materials, a polymer charge transfer material having a hydrazone group having a molecular weight of 1,000 to 500,000 and having at least one kind of low molecular charge transfer material.