JPH03157664A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a laminate type positively chargeable photosensitive body high in sensitivity and durability by incorporating a specified butadiene compound or a distyryl compound as an electric charge transfer material in a charge transfer layer. CONSTITUTION:The charge transfer layer contains the butadiene compound represented by a formula I or the distyryl compound represented by formula II as the charge transfer material. In formulae I and II, each of Ar1 - Ar7 is aryl and at least one of them is substituted; A is an optionally substituted alkylene, arylene, or divalent heterocyclic group; and R1 is H, or optionally substituted alkyl, such aralkyl, or such aryl, thus permitting the obtained laminate type positively chargeable photosensitive body to be reduced in tendency to undergo effects of photodeterioration and deterioration due to ozone accompanied by corona discharge, and to be enhanced in sensitivity and durability.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electrophotographic photoreceptor for positive charging.

PRIOR ART AND PROBLEMS Many organic photoreceptors are of a negatively charged type, and usually have a structure in which a charge generation layer and a charge transport layer are provided in this order on the top of a conductive support.

This is because the charge transport layer is generally formed thicker than the charge generation layer, so it is less affected by abrasion when the photoreceptor is used, and has excellent printing durability.The charge transport material also transports holes. This is due to the fact that many of them are sexual.

However, if an organic photoreceptor with such a configuration is used with negative charging due to corona discharge, a large amount of ozone, nitrogen oxides, etc. will be generated, and these compounds may be adsorbed to the surface of the photosensitive layer or the large surface of the photosensitive layer may be damaged. Since the photoreceptor chemically deteriorates the photoreceptor, it causes problems such as deterioration of the characteristics of the photoreceptor and deterioration of the quality of the copied image, especially when used repeatedly.

Furthermore, when used at high temperatures and high humidity, there are also problems such as image blurring and poor line reproducibility.

In order to solve these problems, research into positively charged photoreceptors is being actively conducted.

However, in a photoreceptor in which a carrier transport layer containing a charge transport material is provided on a charge generation layer, an appropriate charge transport material that can be used for positive charging has not been found, and the photoreceptor has not been put into practical use.

On the other hand, positively charged photoreceptors in which a charge generation layer is provided on a hole transport layer have problems such as the charge generation layer being on the surface side, printing durability, and environmental stability.

Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and is a highly sensitive positively charged type that is less susceptible to photodegradation and ozone deterioration due to corona discharge, and has excellent durability and repeated stability. The purpose is to widen the photoreceptor.

Means for Solving the Problems The present invention provides a laminated positive charging photoreceptor in which at least a charge transport layer and a charge generation layer are sequentially laminated on a conductive support, wherein the charge transport layer is represented by the following general formula [I]. An electrophotographic photoreceptor comprising at least one type of charge transporting material, such as a butadiene compound represented by the formula I or a distyryl compound represented by the following general formula I; Ar, each is an aryl group, at least one of which has a substituent 1
, [wherein Ars, Ar, and Ary are each an aryl group, and at least one has a substituent: A is an alkylene group, an arylene group, or a divalent heterocyclic group, each of which may have a substituent. represents a group: R6 represents hydrogen, each represents an alkyl group, an aralkyl group, or an aryl group which may have a substituent.

When a butadiene compound represented by the general formula [I] or a distyryl compound represented by the general formula [II] is used as the charge transport substance, the charge between the charge generation substance and the charge transport layer and between the charge transport layer and the conductive substrate is reduced. Since the movement is performed smoothly, the photoreceptor properties such as photosensitivity are improved.

In addition, a charge transport layer is formed under the charge generation layer,
Since it is used with a positive charge, the charge transport material can sufficiently exhibit its charge transport function without being affected by environmental deterioration, photodeterioration, etc.

In the general formula IIJ, Ar and =Ar are each an aryl group such as phenyl, and at least one of these groups is a halogen atom, a lower alkoxy group, an N-substituted amino group, or a lower alkyl group. It has more than one type of substituent. Preferred among these substituents are N-substituted amino groups. When neither Ar nor -Ar4 has the above-mentioned substituents, the sensitivity is poor and the compatibility with the resin is also poor.

As the butadiene compound represented by general formula [I],
Specific examples include, but are not limited to, the following.

In shin3 shinnz - Funato [IT], Ars to Ary are each an aryl group such as phenyl, and at least one of these groups is
It is preferable that each group has one or more substituents such as a lower alkoxy group, an N-1f substituted amino group, or a lower alkyl group.1. stomach. Particularly preferred among these substituents is an N-substituted amino group.

When neither Ar nor ~Ar has any substituent, at least one of Ar5-Ar7 is a residue of a heterocyclic ring containing a nitrogen atom or an oxygen atom (for example, carbazole, dioxindane, etc.) may be A
If none of r@-A ry has the above substituents or is not the above heterocyclic residue,
Sensitivity is poor and compatibility with resins is also poor.

In the general formula [I], R1 represents a hydrogen atom, a C, to C1 lower alkyl group, an aralkyl group such as benzyl, or an aryl group such as phenyl, and these groups are any of the substituents explained in Ars to Ar7. It may have.

In general formula [I]1, A is an arylene group such as phenylene,
or a heterocyclic divalent group such as thiol or furan,
The group may also have a substituent (alkyl group, alkoxy group, etc.).

-Funenin [I]] Specifically, the following compounds are used as distyryl compounds; A case of forming such a laminated photoreceptor will be specifically described.

Here, the conductive support in the photoreceptor may be a sheet or drum-shaped foil or plate of copper, aluminum, gold, silver, platinum, iron, palladium, nickel, etc., or a sheet or drum made of these metals. A layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide is applied to a support such as paper or a plastic film by coating or vapor deposition. A formed one can be used.

To form a charge transport layer on such a conductive support, the above-mentioned shipman [I] or "rll charge transport material is dissolved in a solvent together with an appropriate resin, and this solution is added. is applied onto a conductive support and dried to form a conductive material. Note that the thickness of this charge transport layer is 5 μm.
m to 40 μm, preferably 10 μm to 30 μm.

At this time, the content of the charge transport material in the charge transport layer is 0.02 to 2 parts by weight, preferably 0.5 to 1.2 parts by weight, based on 1 part by weight of the binder resin. do.

As the resin for forming the charge transport layer, thermoplastic resins, thermosetting resins, photocurable resins, photoconductive resins, etc., which are known per se, can be used. Examples of suitable binder resins include: are polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acetate-bimaleic anhydride copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal, polyester, phenoxy resin, (meth) ) Acrylic resin, polystyrene, polycarbonate, polyarylate, polystyrene, polyethersulfone, thermoplastic resin such as ABS resin, phenolic resin, epoxy resin, urethane resin, melamine resin, incyanate resin, alkyd resin, silicone resin, thermosetting resin Examples include curable resins such as acrylic resins, and photoconductive 8N resins such as polyvinylcarbazole, polyvinylanthracene, and polyvinylpyrene. However, it is not limited to these.

Solvents used to prepare the coating solution for forming the charge transport layer include alcohols such as methanol, ethanol, and inglobanol, ketones such as acetone, methyl isobutyl ketone, and cyclohexanone, N,
Amides such as N-dimethylformamide, N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydro-7rane, dioxane, cellosolve, calpitol, esters such as methyl acetate, ethyl acetate, chloroform, dichloromethane , aliphatic halogenated hydrocarbons such as dichloroethane, carbon tetrachloride, trichloroethane, benzene, toluene,
Organic solvents such as aromatics such as xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. can be used.

In addition, the charge transport layer further includes a known sensitizer,
Leveling agents, antioxidants, etc. may be added. The charge transporting materials of the general formulas [I] to [I]F of the present invention may be used alone or in a mixture of two or more, or may be mixed with other charge transporting materials to the extent that the effects of the present invention are not impaired. You can.

To form a charge generation layer on the charge transport layer thus formed, an appropriate charge generation material is dissolved together with the same resin and solvent as those used for forming the charge transport layer as described above. The dispersion is applied onto the charge transport layer and dried to form the charge transport layer. The charge generation layer has a thickness of 0.01 to 10 .mu.m, preferably 0.1 to 5 .mu.m.

The charge generation function of the charge generation layer is 0.01 to 1 μm.
The range is fine. However, since this film thickness does not have durability against blade cleaning, it is necessary to provide a surface protective layer.

When used without a surface protective layer, durability can be increased by increasing the thickness of the charge generation layer in the range of 1 μm to 10 μm, but in this case, charge transport within the charge generation layer It is desirable to include a charge transport material within the charge generating layer to improve efficiency.

When the charge generation layer does not contain a charge transporting material, the content of the charge generation material in the charge generation layer is based on 1 part by weight of the binder resin.
The charge generating material is 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight.
Make sure it is by weight.

On the other hand, when the charge-generating layer contains a charge-transporting material, the amount of the charge-generating material is 0.01 to 1 part by weight and the charge transporting material is 0.5 to 2 parts by weight per 1 part by weight of the binder resin. Make it.

Here, in forming the charge transport layer and the charge generation layer, methods for applying the coating solution include dip coating method, ring coating method, spray coating method, spinner coating method, blade coating method, roller coating method, wire coating method, etc. Various coating methods can be used, such as bar coating methods.

Furthermore, in any of the photoreceptors obtained as described above, an intermediate layer can be provided between the conductive support and the photosensitive layer, if necessary.

Here, the materials used for the intermediate layer include polyimide,
Polymers such as polyamide, nitrocellulose, polyvinyl butyral, and polyvinyl alcohol can be used as they are, or low-resistance compounds such as tin oxide, indium oxide, alkylene oxide, and titanium oxide can be dispersed in hardening resins such as acrylic, urethane, epoxy, and melamine. The things that caused
A vapor deposited film of aluminum oxide, zinc oxide, silicon oxide, zirconium oxide, etc. is suitable, and it is desirable to form the film so that the film thickness is 10 μm or less.

Further, in the photoreceptor of the present invention, a surface protective layer may be provided on the surface of the photoreceptor in order to improve its abrasion resistance and ensure more stable performance of the photoreceptor over a long period of time.

Examples of such a surface protective layer include a resin-based protective layer formed using a coating method using a thermosetting resin, a room temperature curable resin, an ultraviolet curable resin, etc., a vapor deposition method, a sputtering method, an ion blating method, and a plasma CVD method. A vacuum thin film protective layer formed using a method or the like is exemplified.

Among these, an amorphous carbon film produced by a plasma CVD method has excellent light transmittance, abrasion resistance, and adhesiveness, and therefore can be applied as a particularly suitable protective layer.

In order to place an amorphous carbon film on the photoreceptor of the present invention, for example, JP-A-63-97961, JP-A-63-979,
Known techniques such as those disclosed in Japanese Patent Application Laid-Open No. 63-97963 may be used.

Example 1 - 10 parts by weight of conductive titanium oxide - 20 parts by weight of thermosetting acrylic resin (AT-50 manufactured by Rohm & Haas) - 70 parts by weight of xylene The above materials were mixed and dispersed for 12 hours using a sand grinder. The mixture was applied onto an aluminum drum by a spray method, and then heated and cured (130° C., 1 hour) to form an intermediate layer (thickness: 5 μm).

・Compound [4] 10 parts by weight ・Polycarbonate (K-1300) 10 parts by weight
Dichloromethane 90 parts by weight The above materials were mixed and dissolved to obtain a charge transport layer coating solution.

The film thickness after drying is 20 mm on the intermediate layer formed with the coating solution first.
A charge transport layer was formed by dip coating to a thickness of μm.

・τ-type metal-free phthalocyanine l! 1jlff
i. Polyvinyl butyral 11 L parts (S-LEC BL-5) Tetrahydro 7ran 98 parts by weight The above materials were dispersed in a paint conditioner for 2 hours to prepare a coating solution for a charge generation layer.

The coating liquid was coated on the charge transport layer by a ring method so that the film thickness after drying was 0.3 μm, thereby producing a positively charged laminated photoreceptor.

Example 2 In the example, the r-type metal-free 7-polycyanine of the charge generation layer was replaced with the σ-type titanyl phthalocyanine as the compound of the charge transport layer [
A photoreceptor was produced in the same manner as in Example 1, except that Compound [4] was changed to Compound [41].

Examples 3 and 4 On the photoreceptors prepared in Examples I and 2, a surface protective layer (1000 layers) consisting of an amorphous carbon film was formed using a plasma CVD method. A plasma CVD apparatus similar to that disclosed in Japanese Patent Application Laid-open No. 63-97961 was used, and the manufacturing conditions were set as follows.

[Plasma conditions] ・Material gas and gas flow rate Hydrogen gas Butadiene gas ・Pressure inside the vacuum chamber ・Substrate temperature ・Discharge frequency ・Discharge power ・Discharge time Comparative example 1 Charge generation layer used in Example 1 on a conductive support After drying, the coating solution was applied so that the film thickness was 0.3 μm. Next, the charge transport layer coating liquid used in Example 1 was applied onto the charge generation layer to a dry film thickness of 20 μm to prepare a photoreceptor.

300 [secm] 15 [scC+nl O, 3[Torrl 50['(:!] 80 [kHzl 150 [W] 3.5L min] Comparative Example 2 Charge generation used in Example 2 in the same manner as Comparative Example 1) A layer coating liquid and a charge transport layer coating liquid were sequentially applied to produce a photoreceptor.

Example fv5 A photoreceptor was produced by changing the charge generation layer in Example Row to a bisazo pigment and polyester (Vylon 200) (7) dispersion film having the following structure. An amorphous carbon film was provided on this photoreceptor in the same manner as in Example 3.4.

Comparative Example 3 A photoreceptor was prepared in the same manner as in Example 5, except that a charge generation layer and a charge transport layer were laminated in this order on a conductive support.

Example 6 As a coating liquid for the charge generation layer, - [type metal-free 7 lysocyanine o, i parts by weight - polycarbonate 1 part by weight - tetrahydrofuran 10 parts by weight - Compound [4]
A photoreceptor was prepared in the same manner as in Example 1, except that a charge generating layer containing 0.5 parts of Ii was used and the charge generation layer was formed to have a film thickness of 4 pts after drying.

Example 7 A photoreceptor was produced in the same manner as in Example 6 except that the bisazo pigment used in Example 5 was used instead of the τ-type metal-free phthalocyanine.

Comparative Example 4 A photoreceptor was produced in the same manner as in Example 1, except that the charge transport material used in the charge transport layer in Example 1 was the following hydrazone compound.

Comparative Example 5 A photoreceptor was produced in the same manner as in Example 1, except that a stilbene compound other than the charge transport material used in the charge transport layer in Example 1 was used.

Comparative Example 6 A photoreceptor was produced in the same manner as in Example 1, except that the charge transport material used in the charge transport layer in Example 1 was the following enamine compound.

Furthermore, with the developing device removed, electrophotographic process 1
After repeating 000 times (7) V,,E,/2,DDR,
was measured.

Further, for the negatively charged photoreceptor produced in Comparative Example 1.2, similar measurements were performed using an electrophotographic printer (SP-130) as is.

The results are shown in Table 1.

(Hereinafter, blank space) The photoreceptors obtained in Evaluation Examples 1 to 4.6 and Comparative Examples 4 to 6 were printed on a commercially available electrophotographic printer (NISSHO-ELEC).
The initial surface potential VO<V) and the amount of exposure required to reduce the initial surface potential to 1/2 when a TRON rcs (5P-130) was modified to have a positive charging specification and corona charged at +6KV. (erg/cm), the decay rate DDR, (%) of the initial potential when left in the dark for 1 second was measured.

Table 1 A similar evaluation was conducted after modifying the battery to a positive charging specification. Comparative example 3
For details, copy machine (manufactured by Minolta Camera Co., Ltd., EP-50
) was used as is to carry out similar measurements.

The results are summarized in Table 2.

Table 2 Next, for the photoreceptors obtained in Example 3.4.6 and Comparative Examples 1 and 2, 10,000 copies were made using the same evaluation machine as above, and the electrostatic properties and image quality were evaluated. We conducted an evaluation.

For Example 5.7, a commercially available copying machine (manufactured by Minolta Camera Co., Ltd., EP-50) was used as a positively charging photoreceptor having a charge transport layer and a charge generation layer on a conductive support according to the present invention. High sensitivity could be achieved by using a specific butashun-based compound or distyryl-based compound as the charge transport material in the charge transport layer. Furthermore, by providing a surface protective layer, a photoreceptor was obtained that also had satisfactory printing durability.

When a surface protective layer is not provided, the same effect can be achieved by increasing the thickness of the charge generation layer and incorporating a butadiene compound or a distyryl compound used in the charge transport layer.

Claims (1)

[Scope of Claims] 1. A laminated positive charging photoreceptor comprising at least a charge transport layer and a charge generation layer sequentially laminated on a conductive support, wherein the charge transport layer is represented by the following general formula [I] An electrophotographic photoreceptor characterized by containing at least one butadiene compound or a distyryl compound represented by the following general formula [II] as a charge transporting material; In the formula, Ar_1, Ar_2, Ar_3, and Ar_4 are each aryl groups, and at least one has a substituent], ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [II] [In the formula, Ar_5, Ar_6, and Ar_7 are each is an aryl group, at least one of which has a substituent; A represents an alkylene group, an arylene group, or a divalent heterocyclic group, each of which may have a substituent; R_1 is hydrogen,
represents an alkyl group, an aralkyl group, or an aryl group, each of which may have a substituent. 2. The charge generation layer contains at least one type of butadiene compound represented by the general formula [I] according to claim 1 or a distyryl compound represented by the general formula [II] according to claim 1. The electrophotographic photoreceptor according to claim 1. 3. The electrophotographic photoreceptor according to claim 2, wherein the charge generation layer has a thickness of 1 to 10 μm. 4. The electrophotographic photoreceptor according to claim 1, wherein the protective layer is formed on the charge generation layer. 5. An electrophotographic photoreceptor characterized in that the protective layer is an amorphous carbon film formed by plasma CVD.