JPH01134456A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability by incorporating a polymer of alkyleneimine substituted by a specified hydrazone derivative in an electric charge transfer layer. CONSTITUTION:The charge transfer layer contains at least one of the polymers of alkyleneimines substituted by hydrazone derivatives represented by formula I in which R1 is H, optionally substituted aryl or such aralkyl; each of R2 and R3 is optionally substituted straight or branched alkyl, such aralkyl, or the like, each optionally same or different, and each may combine with each other to form a ring; Y is 1-10C alkyl or alkoxy, or halogen; n is an integer of >=2; m is an integer of 2-20; and (l) is an integer of 0-4, thus permitting sensitivity and durability to be both enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to a highly sensitive and highly durable electrophotographic photoreceptor containing a hydrazone derivative-substituted polyalkyleneimine polymer in a charge transport layer. Regarding photoreceptors.

[Conventional technology and its problems]

In recent years, the development of copiers and printers using electrophotography has been remarkable, with various forms and types of models being developed depending on their uses, and correspondingly, the photoreceptors used in them have also changed from inorganic to organic materials. A wide variety of products are being developed.

Conventionally, inorganic compounds have been mainly used as electrophotographic photoreceptors due to their sensitivity and durability. Examples of these inorganic compounds include zinc oxide, cadmium sulfide,
Examples include selenium. However, these often use harmful substances, and their disposal becomes a problem and causes pollution. Furthermore, when selenium, which has good sensitivity, is used, it is necessary to form a thin film on a conductive substrate by a vapor deposition method or the like, resulting in poor productivity and increased costs. In recent years, amorphous silicon has attracted attention as a non-polluting inorganic photoreceptor, and its research and development is progressing. However, although these are also very good in sensitivity, they mainly require plasma C
Since the vD method is used, its productivity is extremely low.
Both the photoreceptor cost and the running cost are large.

On the other hand, organic photoreceptors can be incinerated and have the advantage of being non-polluting, and many of them can be coated to form thin films, making mass production easy. Therefore, it has the advantage of being able to significantly reduce costs and being able to be processed into various shapes depending on the application. However, problems remain in the sensitivity and durability of organic photoreceptors, and there is a strong desire for an organic photoreceptor with high sensitivity and high durability.

Various methods have been proposed to improve the sensitivity of organic photoreceptors, but currently the mainstream is a functionally separated photoreceptor with a two-layer structure in which the functions are separated into a charge generation layer and a charge transport layer. There is. For example, charges generated in the charge generation layer due to exposure to light are injected into the charge transport layer and pass through the charge transport layer to the surface.

By neutralizing the surface charge, an electrostatic latent image is formed on the surface of the photoreceptor. Compared to the single-layer type, the function-separated type has a smaller possibility that generated charges will be captured, and the charges can be efficiently transported to the photoreceptor surface without each layer having its own function inhibited (U.S. patent No. 280354
No. 1).

As the organic charge-generating material used in the charge-generating layer, compounds that absorb the energy of irradiated light and efficiently generate charges are selectively used, such as azo pigments (
JP-A-54-14967), metal-free phthalocyanine pigments (JP-A-60-143346), metal phthalocyanine pigments (JP-A-50-16538), squarylium salts (JP-A-53-27033) ), etc.

It is necessary to select a compound that has a high charge injection efficiency from the charge generation layer into the charge transport layer and also has a high charge mobility within the charge transport layer. For this purpose, compounds with low ionization potential and compounds that easily generate radical cations are selected, among which are triarylamine derivatives (Japanese Patent Laid-Open No. 53
-47260), hydrazone derivatives (Japanese Unexamined Patent Publication No. 57
-101844), oxadiazole derivatives (Japanese Patent Publication No. 34-5466), pyrazoline derivatives (Japanese Patent Publication No. 52-4188), stilbene derivatives (Japanese Patent Publication No. 58-198043), triphenylmethane derivatives (Japanese Patent Publication No. 58-198043), (Japanese Patent Publication No. 45-555) etc. are often used.

However, the charge mobility of these materials is small compared to that of inorganic materials, and the sensitivity is still unsatisfactory.

It has been proposed that charges in organophotoreceptors move between molecules by a hopping mechanism. Mobility is strongly influenced by its interhop distance and deep structural traps. Regarding this distance between hopping, the charge transport functional group is incorporated into the side chain or the main chain, compared to a charge transport layer with a structure in which the aforementioned low molecular weight compounds such as triarylamine derivatives and hydrazone derivatives are dispersed in the binder. A polymeric charge transporting material that has a high molecular weight is preferred. For example, polyvinylcarbazole (Japanese Patent Publication No. 34-10966), polyvinylanthracene, etc. have been proposed. However, although these are preferable in terms of the distance between hoppings, the present situation is that deep structural traps exist, and as a result, the charge mobility has not been improved. Furthermore, these polymer compounds are often insoluble in organic solvents, creating difficulties when producing electrophotographic photoreceptors.

On the other hand, in a series of electrophotographic processes such as charging, exposure, development, transfer, and static elimination, photoreceptors are placed under extremely harsh conditions, and their ozone resistance and abrasion resistance are particularly problematic. These binders and retainers are used to improve durability! 1
Development of 715 is progressing, but nothing satisfactory has yet been achieved.

[Means for solving problems]

As a result of intensive studies on electrophotographic photoreceptors with high sensitivity and high durability, the present inventors found that an electrophotographic photoreceptor containing a specific polyalkyleneimine polymer in the charge transport layer has excellent sensitivity and durability. This led to the present invention.

That is, the present invention provides an electrophotographic photoreceptor comprising a conductive support, a charge generation layer, and a charge transport layer as essential components,
General formula (1) %Formula% (wherein, R5 is any one of a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group) Rz and R2 are the same or different and represent any of an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, and an optionally substituted aralkyl group. , R1 and R1 may be taken together to form a ring, Y represents an alkyl group or alkoxy group having 1 to 10 carbon atoms, or a halogen atom, n is an integer of 2 or more, and m is The integer 1 of 2 to 20 is an integer of O to 4. .

The hydrazone derivative-substituted polyalkyleneimine polymer represented by general formula (1) can be easily synthesized, but the method of synthesis is not particularly limited.

One method is to combine a linear polyalkyleneimine with the general formula (
This is a method of reacting with the leaving group-containing hydrazone derivative shown in 2).

(In the formula, R,, R,, R3, Y and are each represented by the formula (
1) is the same as R, , R2, R, , Y and , and X
represents a halogen atom) Another method is a method of reacting the aminohydrazone derivative represented by the general formula (3) with α,ω-dihalogenoalkylene.

R.

(In the formula, RI+ R2, R1Y and are each represented by the formula (
Same as R+, RI R3, Y and in 1).

) Furthermore, for the hydrazone derivative-substituted polyethyleneimine polymer and the hydrazone derivative-substituted polytrimethyleneimine polymer, a method of ring-opening polymerization of an aziridine derivative or azetidine derivative represented by general formula (4) can also be used.

R.

(In the formula, p is 2 or 3, and R,, R2, R3, Y and are respectively R1, lh, R3, Y in formula (1)
and are the same. ) The degree of polymerization n of the hydrazone derivative-substituted polyalkyleneimine polymer used in the present invention is 2 or more, preferably 4 or more. If it is smaller than this, the effect of shortening the distance between hoppings due to the polymer effect will be poor, and the sensitivity will not improve. The number m of methylene groups in the alkylene group is 2 to 20, and it is difficult to synthesize a hydrazone derivative-substituted polymer in which m is 1 or 0. Moreover, if the steel is larger than 20, the distance between charge hopping becomes large, which is not preferable.

Examples of the main chain polyalkyleneimine of the hydrazone derivative-substituted polyalkyleneimine polymer used in the present invention include polyethyleneimine, polytrimethyleneimine, polytetramethyleneimine, polypentamethyleneimine,
Examples include polyhexamethyleneimine, polyhebutamethyleneimine, polyoctamethyleneimine, polynonamethyleneimine, polyocmethyleneimine, polydodecamethyleneimine, polyundecamethyleneimine, etc.
On the other hand, the side chain portion of the hydrazone derivative is, for example, the formula (A)
-(V) include, but are not limited to.

（＾） （B） （C）（
D) (E) (F)
(G) (H) (
I) (J) (M) (N)
(0) (P) (Q) (S) (T) (
U) (V) These hydrazone derivative-substituted polyalkyleneimine polymers are soluble in many solvents, such as benzene,
Aromatic solvents such as toluene, xylene, tetralin, and chlorobenzene, halogen solvents such as dichloromethane, chloroform, trichloroethylene, and tetrachloroethylene, ester solvents such as methyl acetate, ethyl acetate, propyl acetate, methyl formate, and ethyl formate, acetone, and methyl ethyl ketone. It is soluble in ketone solvents such as diethyl ether, dipropyl ether, and tetrahydrofuran, alcohol solvents such as methanol, ethanol, and isopropyl alcohol, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and the like.

In producing an electrophotographic photoreceptor, a charge generation layer and a charge transport layer are formed in the form of a thin film on a conductive support. As the base material of the conductive support, metals such as aluminum and nickel, metal-deposited polymer films, metal-laminated polymer films, etc. can be used, and the conductive support is configured in the form of a drum or sheet. .

The charge generation layer is made of a charge generation material and, if necessary, a binder and additives, and can be produced by a method such as a vapor deposition method, a plasma CVD method, or a coating method.

The charge generating material is not particularly limited, and any organic charge generating material or inorganic charge generating material is suitable as long as it absorbs the irradiated light of a specific wavelength and can efficiently generate a charge. It can be used for.

Examples of organic charge generating materials include perylene pigments, polycyclic quinone pigments, metal-free phthalocyanine pigments, metal phthalocyanine pigments, bisazo pigments, trisazo pigments, thiapyrylium salts, squarylium salts, azulenium pigments, etc. A charge-generating layer can be formed by dispersing it in an agent and coating it. Inorganic charge generating materials include selenium, selenium alloys, cadmium sulfide,
Examples include zinc oxide and amorphous silicon.

The thickness of the formed charge generation layer is preferably 0.1 to 2.04 mm, more preferably 0.2 to 1.0 mm. It is OIm.

Next, a charge transport layer containing a hydrazone derivative-substituted polyalkyleneimine polymer represented by the general formula (1) is formed in the form of a thin film on top of the charge generation layer. A coating method is mainly used to form a thin film, in which a hydrazone derivative-substituted polyalkyleneimine polymer represented by general formula (1) is dissolved in a solvent together with a binder if necessary, and coated on the charge generation layer. All you have to do is press it, then dry it.

The solvent to be used is not particularly limited as long as it dissolves the hydrazone derivative-substituted polyalkyleneimine polymer and the binder used if necessary, but does not dissolve the charge generation layer.

The binder that can be used as necessary is not particularly limited as long as it is an insulating resin, and examples include condensation polymers such as polycarbonate, polyarylate, polyester, and polyamide, polyethylene, polystyrene, and styrene-acrylic copolymers. , polyacrylate, polymethacrylate, polyvinyl butyral, polyacrylonitrile, polyacrylamide, acrylonitrile-butadiene copolymer, addition polymers such as polyvinyl chloride, polysulfone,
Polyether sulfone, silicone resin, etc. are used as appropriate, and one type or a mixture of two or more types can be used.

The amount of the binder used is 0 for the hydrazone derivative-substituted polyalkylene imine polymer represented by the general formula (1).
．． The weight ratio is 1 to 3, preferably 0.1 to 2. If it is larger than this, the concentration of the charge transporting material in the charge transporting layer becomes small, resulting in poor sensitivity. The hydrazone derivative-substituted polyalkyleneimine polymer represented by the general formula (1) has excellent thin film-forming properties, flexibility, and adhesive properties, and can form a charge transport layer by itself without using a binder. It can also be formed.

Further, in the present invention, it is also possible to use a known charge transporting material as described above in combination with the hydrazone derivative-substituted polyalkyleneimine polymer, if necessary.

The coating means is not limited, and for example, a bar coater, calendar coater, gravure coater, blade coater, spin coater, dip coater, etc. can be used as appropriate.

The thickness of the charge transport layer formed as described above is preferably 10 to 50Jn, more preferably 10 to 30Jn.
It is a. If the film thickness is greater than 50 -, it will take more time to transport the charge, and the probability that the charge will be captured will also increase, causing a decrease in sensitivity. On the other hand, 1
If it is smaller than 01 m, the mechanical strength will decrease and the life of the photoreceptor will be shortened, which is not preferable.

As described above, an electrophotographic photoreceptor containing a hydrazone derivative-substituted polyalkyleneimine polymer represented by the general formula (1) in the charge transport layer can be produced. An undercoat layer, an adhesive layer, a barrier layer, etc. can be provided between the generation layers, if necessary, and for example, polyvinyl butyral, phenol resin, polyamide resin, etc. are used. Furthermore, a surface protective layer can also be provided on the surface of the photoreceptor.

An electrophotographic photoreceptor obtained as described above.

In use, first the surface of the photoreceptor is negatively charged using a corona charger or the like. After being charged and exposed to light, charges are generated in the exposed portion within the charge generation layer, and the positive charges are injected into the charge transport layer and then transported to the surface, where the negative charges on the surface are neutralized.

On the other hand, negative charges remain in the unexposed areas, which form an electrostatic latent image. Toner adheres to this area, is transferred onto paper, etc., and is fixed.

Further, in the present invention, it is also possible to produce an electrophotographic photoreceptor by first providing a charge transport layer on a conductive support and then providing a charge generation layer thereon. In this case, the surface of the photoreceptor is first positively charged, and after exposure, the negative charge neutralizes the surface charge of the photoreceptor, and the positive charge is transported to the conductive support through the charge transport layer. It's going to happen.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples.

Synthesis example Equipped with a stirring bar, thermometer, cooling tube, and dropping funnel 2!
Add p-aminoacetophenone-N,N- to the fourth flask.
Add 100 g of diphenylhydrazone and 1 portion of dimethylformamide! It was dissolved in Add 1,2-short ethane 9 to this dimethylformamide solution while cooling with ice.
200 d of 4 g of dimethylformamide solution was slowly added dropwise while stirring. After the dropwise addition was completed, the reaction system was heated to 100'C and stirred for 5 hours. Thereafter, the temperature was lowered to room temperature, and then poured into a saturated aqueous sodium hydrogen carbonate solution 31. Ethyl acetate 31 was added thereto and an extraction operation was performed. After washing the ethyl acetate layer once with water, it was condensed to 300 mZ. The concentrated ethyl acetate solution was added dropwise to diethyl ether 32 at room temperature to perform reprecipitation. The obtained precipitate was dissolved again in 300 g of ethyl acetate and added dropwise to 31 g of diethyl ether at room temperature. After repeating the same operation three times, the resulting precipitate was collected by filtration, washed three times with diethyl ether, and dried at room temperature to obtain 47 g of a polymer.

II-NMR measurement confirmed that the polymer was a hydrazone derivative-substituted polyethyleneimine polymer represented by formula (5) in Table 1.

Further, as determined by gel permeation chromatography, the number average molecular weight was -6200 in terms of polystyrene.

By similar operations, various hydrazone derivative-substituted polyalkyleneimine polymers shown in (6) to Measurement in Table 1 were synthesized.

Example-1 5 g of vanadyl oxide phthalocyanine and 5 g of butyral resin (S-LEC BM-2, manufactured by Tanesui Chemical Co., Ltd.) were added to 90 ml of cyclohexanone and kneaded in a ball mill for 24 hours. The resulting dispersion was applied onto an aluminum plate using a bar coater so that the film thickness after drying was 0.5 shavings, and dried to form a charge generation layer.

Next, N represented by formula (5) obtained in the synthesis example.

10 g of N-diphenylhydrazone-substituted polyethyleneimine polymer was dissolved in 90 m7 of methylene chloride, and this was coated on the previously formed charge generation layer using a blade coater so that the film thickness after drying would be 25 mm, and dried. , to form a charge transport layer.

The electrophotographic photoreceptor thus produced was tested at -5,5k using an electrostatic copying paper tester SP-428 manufactured by Kawaguchi Denki ■.
When charged with a corona voltage of v, the initial surface potential v0
was -780v. The surface potential V after being left in the dark for 5 seconds was -750V. Next, the oscillation wavelength is 780 nm.
The half-tooth exposure amount E+/□ was determined to be 0.5 μJ/cm'', and the residual potential was -17V.

Next, Vll+v after repeating the above operation 2000 times
,.

El/2. When VR was measured, v, ==
-740V.

Vs-730V, Etzz=0.6 μJ/cm”
, VR = 18V, and it was found that the performance as a photoreceptor was hardly deteriorated and that it exhibited high durability.

Examples 2 to 6 Electrophotographic photoreceptors were produced in the same manner as in Example 1, except that hydrazone derivative-substituted polyalkylene imine polymers represented by formulas (6) to 00) in Table 1 were used as charge transport materials, respectively. Created.

The performance of each of the produced electrophotographic photoreceptors was evaluated using an electrostatic copying paper tester SP-428 manufactured by Kawaguchi Denki ■. The results are shown in Table-1. Furthermore, after 2000 repetitions (DVo, Vs, Etzz, VR measurement results) are shown in Table 2.

Table 1 Table-1 continued Table 2 Example-7 A charge generation layer was formed on an aluminum plate in the same manner as in Example-1, and then a charge generation layer was formed on an aluminum plate using the N,N-diphenylhydrazone-substituted polyethyleneimine polymer represented by formula (5). 5 g of the combined material and 5 g of polycarbonate resin (Lexan 141-111, manufactured by Engineering Plastics ■) were dissolved in 90 methylene chloride, and this was dried with a blade coater on the previously formed charge generation layer to a film thickness of 254 mm. A charge transport layer was formed by coating and drying.

When the electrophotographic photoreceptor thus produced was evaluated in the same manner as in Example-1, v, = 830V, Vs =
820V, EIyz=0.6 pJ/cm”.

Vl=-20V, and even when a binder was included, the performance was hardly inferior.

Example-8 An electrophotographic photoreceptor was produced and evaluated in the same manner as in Example-1, except that the charge-generating material vanadyl oxide phthalocyanine in Example-1 was replaced with an azo pigment indicated by 2〇. However, Vo”” 770V+ Vs””
760L Eryz=0.41#J/C0l! IV
l=-21V, Vo=-75 after 2000 repetitions
0V.

Vs=740L H+7g=0.511J/cm”
+V*=20V. As described above, it was found that high sensitivity and high durability were also exhibited when an azo pigment was used as the charge generating material.

10D Comparative Example Electron production was performed in the same manner as in Example-7, except that the hydrazone derivative represented by 2G21 was used instead of the N,N-diphenylhydrazone-substituted polyethyleneimine polymer represented by formula (5) in Example-7. A photographic photoreceptor was produced and evaluated.

The surface potential before exposure is vo=-770v, vs=-75
0v, and no difference was observed from Examples 1 to 8 described above, but E+1t=2.1BJ/cra'', which was a poor half-decreased exposure amount.Also, the residual potential was v, I=-3
It was 2v.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention, which is characterized by containing a hydrazone derivative-substituted polyalkyleneimine polymer in its charge transport layer, has a stable initial potential, small dark decay (and high sensitivity).

Furthermore, it shows little deterioration due to repeated use and has excellent durability.

Applicant's agent Kaoru Furutani

Claims (1)

[Claims] In an electrophotographic photoreceptor having a conductive support, a charge generation layer, and a charge transport layer as essential components, general formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) ( In the formula, R_1 represents a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted aralkyl group. R_2 and R_3 are the same Alternatively, R_2 and R_3 together represent an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted aralkyl group. A ring may be formed.Y represents an alkyl group or alkoxy group having 1 to 10 carbon atoms, or a halogen atom.n
is an integer of 2 or more, m is an integer of 2 to 20, and l is an integer of 0 to 20.
It is an integer of 4. ) An electrophotographic photoreceptor comprising a hydrazone derivative-substituted polyalkyleneimine polymer represented by the following formula in a charge transport layer.