JPH01134457A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability by incorporating a polymer of alkyleneimine substituted by a specified triarylamine derivative in an electric charge transfer layer. CONSTITUTION:The charge transfer layer contains at least one of the polymers of alkyleneimines substituted by triarylamine derivatives represented by formula I in which each of R1-R3 is H, optionally substituted straight or branched alkyl or alkoxy, optionally substituted aryl or aryloxy, or such aralkyl, or the like, optionally same or different from each other; each of R4 and R5 is optionally substituted straight or branched alkyl, optionally substituted aryl, or such aralkyl, optionally same or different from each other; (n) is an integer of >=2; and (m) is an integer of 2-20, thus permitting sensitivity and durability to be both enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrophotographic photoreceptors, and more particularly, to electrophotographic photoreceptors having high sensitivity and high durability containing a triarylamine derivative-substituted polyalkyleneimine polymer in a charge transport layer. The present invention relates to an electrophotographic photoreceptor.

[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 the purpose, and correspondingly, the photoreceptors used in these machines have also changed from inorganic to organic materials. A 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, cardium sulfide, and 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 methods have very good sensitivity, they mainly use the plasma CVD method when forming thin films, so their productivity is extremely low, and both photoreceptor costs and running costs are high. There is.

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, transported through the charge transport layer to the surface, and by neutralizing the surface charges, an electrostatic latent image is formed on the surface of the photoreceptor. be done. 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. 28035
No. 41).

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.

As the charge transport material used in the charge transport layer, it is necessary to select a compound that has high charge injection efficiency from the charge generation layer and also has high charge mobility within the charge transport layer.

For this purpose, compounds with small ionization potential,
Compounds that are likely to generate radical cations are selected, but
Among them, triarylamine derivatives (JP-A-53-472
60), hydrazone derivatives (JP-A-57-101)
No. 844), oxadiazole derivatives (Japanese Patent Publication No. 34
-5466), pyrazoline derivatives (Special Publication No. 52-
4188), stilbene derivatives (JP-A-58-1
98043), triphenylmethane derivatives (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. Although the development of binders and protective layers is progressing for the purpose of improving these durability, nothing satisfactory has yet been obtained.

[Means for Solving 5 Problems] As a result of intensive studies on highly sensitive and highly durable electrophotographic photoreceptors, the present inventors have developed an electrophotographic photoreceptor containing a specific polyalkylene imine polymer in a charge transport layer. The photoreceptor has a sensitivity,
It was discovered that both durability is excellent, leading 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) (wherein Rt, Rt, and Rs are the same or different and each represents a hydrogen atom, an optionally substituted linear or branched alkyl group or alkoxy group, an optionally substituted aryl group, or Represents any of an aryloxy group, an optionally substituted aralkyl group or aralkyloxy group, a halogen atom, or an amino group represented by Rs in the formula -N8, where Ra and Rs are the same or different and are substituted. an optional straight-chain or branched alkyl group, an optionally substituted aryl group,
Represents any aralkyl group that may be substituted.

n is an integer of 2 or more, and ■ is an integer of 2 to 20.

The present invention provides an electrophotographic photoreceptor comprising a triarylamine derivative-substituted polyalkyleneimine polymer represented by the following formula in a charge transport layer.

Although the triarylamine derivative-substituted polyalkyleneimine polymer represented by the general formula (1) can be easily synthesized, 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 triarylamine derivative shown in 2).

(In the formula, R, , R, , R3 are each R in formula (1)
It is the same as 1°R,,R,, and X represents a halogen atom. : Another method is a method in which the aminotriarylamine derivative represented by the general formula (3) is reacted with α,ω-dihalogenoalkylene.

(In the formula, R1 + Rz, Ih are the same as Rl + RI R2 in formula (1), respectively.) Also, regarding the triarylamine derivative-substituted polyethyleneimine polymer and the triarylamine derivative-substituted polytrimethyleneimine polymer Alternatively, a method of ring-opening polymerization of an aziridine derivative or an azetidine derivative represented by the general formula (4) can be used.

(In the formula, Rt, RZ, and R3 are the same as R1゜Rt and R3 in formula (1), respectively, and 1 is 2 or 3.) The polymerization degree n of coalescence is 2 or more,
Preferably it is 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 2
0, and it is difficult to synthesize a triarylamine derivative-substituted polymer in which m is 1 or O. Also, I is 20
If it is larger, the distance between charge hopping becomes large, which is not preferable.

Examples of the main chain polyalkyleneimine of the triarylamine derivative-substituted polyalkyleneimine polymer used in the present invention include polyethyleneimine, polytrimethyleneimine, polytetramethyleneimine, polypentamethyleneimine, polyhexamethyleneimine, and polyalkyleneimine. Examples include hebutamethyleneimine, polyoctamethyleneimine, polynonamethyleneimine, polydecamethyleneimine, polydodecamethyleneimine, polyundecamethyleneimine, etc. On the other hand, triarylamine derivatives having side chain moieties include, for example. Examples include, but are not limited to, those shown in formulas (A) to (0).

(υ) (C) (E) (F)I (G) (H) (K)
(L)(N) These triarylamine derivative-substituted polyalkyleneimine polymers are 1. soluble in many solvents, e.g.
Aromatic solvents such as benzene, toluene, xylene, tetralin, and chlorobenzene, halogen solvents such as dichloromechen, chloroform, trichloroethylene, and tetrachloroethylene, and ester solvents such as methyl acetate, ethyl acetate, propyl acetate, methyl formate, and ethyl formate. , soluble in ketone solvents such as acetone and methyl ethyl ketone, ether solvents such as diethyl ether, dipropyl ether, and tetrahydrofuran, alcohol solvents such as methanol, ethanol, and isopropyl alcohol, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc. .

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 formed in the form of a drum or sheet. do.

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 irradiated light of a specific wavelength and can efficiently generate charges. It can be used.

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, and azulenium pigments. dispersed in a binder,
A charge generation layer can be formed by coating. Examples of the inorganic charge generating material include selenium, selenium alloys, cadmium sulfide, zinc oxide, amorphous silicon, and the like.

The thickness of the formed charge generation layer is preferably 0.1 to 2.0 -, more preferably 0.2 to 1. OI! It is m.

Next, a charge transport layer containing a triarylamine 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 triarylamine 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. It can be coated and then dried.

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

The binder used as necessary is not particularly limited as long as it is an insulating resin; for example, polycarbonate,
Condensation polymers such as polyarylate, polyester, and polyamide, polyethylene, polystyrene, styrene-acrylic copolymer, polyacrylate, polymethacrylate 1, polyvinyl butyral, polyacrylonitrile, polyacrylamide, acrylonitrile-butadiene copolymer, polyvinyl chloride addition polymers such as 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 0.1 to 3 weight ratio, preferably 0.1 to 2 weight ratio to the triarylamine derivative substituted polyalkylene imine polymer represented by formula (1) -a. be. 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 triarylamine derivative-substituted polyalkyleneimine polymer represented by the general formula (1) has excellent thin film-forming properties, flexibility, and adhesive properties, and can transport charges by itself without using a binder. It is also possible to form a layer.

Further, in the present invention, it is also possible to use the above-mentioned known charge transporting materials in combination with the triarylamine derivative-substituted polyalkyleneimine polymer, if necessary.

The coating method is not limited, for example, bar coater,
A 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 50 mm, more preferably 10 to 30 mm. If the film thickness is greater than 50 m, it will take more time to transport the charges, and the probability that the charges will be captured will also increase, causing a decrease in sensitivity. On the other hand, 10
If it is smaller than -, 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 the triarylamine derivative-substituted polyalkyleneimine polymer represented by the general formula (1) in the charge transport layer can be produced.
In the present invention, an undercoat layer, an adhesive layer, a barrier layer, etc. can be further provided between the conductive support and the charge generation layer as required. For example, polyvinyl butyral, phenolic resin,
Polyamide resin or the like is used. It is also possible to provide a surface protective layer on the surface of the photoreceptor.

When using the electrophotographic photoreceptor obtained as described above, the surface of the photoreceptor is first 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. Become.

〔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 21 equipped with a stirring bar, thermometer, cooling tube, and dropping funnel.
86g of 4-aminotriphenylamine in a four-eye flask
and dissolved in dimethylformamide 11. Add 1 ml to this dimethylformamide solution while cooling with ice.
．． A solution of 94 g of 2-short ethane in 200 g of dimethylformamide was slowly added dropwise with stirring. After the dripping is finished,
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,
Concentrated to 0-. The concentrated ethyl acetate solution was added dropwise to diethyl ether 31 at room temperature to perform reprecipitation. The obtained precipitate was dissolved again in 300 ml of ethyl acetate and added dropwise to 32 ml 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 56 g of a polymer. - H-NMR measurement confirmed that the polymer was a triarylamine derivative-substituted polyethyleneimine polymer represented by formula (5) in Table 1.

Further, the number average molecular weight was determined to be 4700 in terms of polystyrene by gel permeation chromatography.

By similar operations, triarylamine derivative-substituted polyalkyleneimine polymers shown in formulas (6) to 00 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 Miki Kagaku ■) were added to cyclohexanone 90- 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 would be 0.5 -, and dried to form a charge generation layer.

Next, the triphenylamine-substituted polyethyleneimine polymer Log shown by the formula (5) obtained in the synthesis example was dissolved in methylene chloride 90-, and this was dried with a blade coater on the previously formed charge generation layer. The film thickness is 25. A was applied 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 -830v. The surface potential V after being left in the dark for 5 seconds was -820V. Next, the oscillation wavelength is 780n.
Irradiate with a semiconductor laser of m, and the exposure amount is halved t! When tzz was determined, it was 0.6 tlJ/cwI'', and the residual potential Vl was -24V.

Next, V11+V after repeating the above operation 2000 times
,.

When El/l and VR were measured, v, =
-B20V.

Vs=812V, E+zz=0.7637cm",
It was found that the photoreceptor was VR-31V, and its performance as a photoreceptor had hardly deteriorated and it exhibited high durability.

Examples 2 to 6 Formulas (6) to 0(I) in Table 1 were used as charge transport materials, respectively.
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except for using the triarylamine derivative-substituted polyalkyleneimine polymer shown below.

The performance of each of the produced electrophotographic photoreceptors was evaluated using electrostatic copying paper test equipment fisP-428 manufactured by Kawaguchi Denki ■. The results are shown in Table 1. Also, V11+ VS+ El/2 after 2000 repetitions
1 The measurement results of Vl are shown in Table-2.

Table 1 Continuation of Table 1 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 triphenylamine-substituted polyethyleneimine polymer represented by formula (5) was formed. 5g, polycarbonate resin (Lexan 141-111.

Engineering Plastics ■) was dissolved in 90-methylene chloride, and this was coated on the previously formed charge generation layer using a blade coater so that the film thickness after drying was 25-25-2, and then dried to transfer charges. formed a layer.

When the electrophotographic photoreceptor thus produced was evaluated in the same manner as in Example-1, v0=820L Vs=
810V+E+zz=0.6 pJ/cs+
”.

V+*=27V, and there was almost no deterioration in performance even when a binder was included.

Example-8 An electrophotographic photoreceptor was produced 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 represented by the formula Ql).
When I evaluated it, Vo=760V+Vs=750
L EI/l=0.1 μJ/cva"+Vt"-30
V, repeat 2000 times, then Vo = 750V
.

Vs"" 745L Et/z=0.7 jlJ/c
ta"+V*=32 V. Thus, it was found that high sensitivity and high durability were exhibited even when an azo pigment was used as the charge generating material.

Comparative Example In Example 7, formula 02) was used instead of the triphenylamine-substituted polyethyleneimine polymer represented by formula (5).
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 7 except that the triphenylamine derivative represented by was used.

Surface potential before exposure is V@=-770V, VS=-75
0V, and no difference was observed from the above-mentioned Examples 1 to 8, but El/2 = 2.2 p J/cn+'', and the half-decreased exposure amount was poor.Also, the residual potential was V*=-
It was 45v.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention, which is characterized by containing the triarylamine 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, R_2, and R_3 are the same or different and are a hydrogen atom, an optionally substituted linear or branched alkyl group or alkoxy group, an optionally substituted aryl group or aryloxy group, a substituted an optional aralkyl group or aralkyloxy group, a halogen atom,
Represents any of the amino groups represented by the formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R_4 and R_5 are the same or different and are optionally substituted linear or branched alkyl groups, represents either an optionally substituted aryl group or an optionally substituted aralkyl group. n is an integer of 2 or more, and m is an integer of 2 to 20. ) An electrophotographic photoreceptor comprising a triarylamine derivative-substituted polyalkyleneimine polymer represented by the following formula in a charge transport layer.