JPH02269360A - Memory type electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the efficient memory type electrophotographic sensitive body by providing an intermediate layer contg. poly(3-alkyl thiophene) subjected to a doping treatment with iodine between a conductive base and a photoconductive layer. CONSTITUTION:The intermediate layer contg. the poly(3-alkyl thiophene) subjected to the doping treatment with the iodine is provided between the conductive base and the photoconductive layer. While the intermediate layer may be formed of the poly(3-alkyl thiophene) alone, the layer may be in the state of being mixed with other resins. The poly(3-alkyl thiophene) is incorporated at least at >=10wt.%, more preferably >=20wt.% into the intermediate layer. The doping treatment is usually executed by exposing the layer to the vapor of the iodine. The memory type latent image is formed in this way without degrading the performance of the photosensitive body and at the light quantity of image exposure level.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a memory photoreceptor for electrophotography.

(Prior art) Among the basic processes of electrophotography: charging, exposure, development, and transfer, systems have been developed that omit the image exposure process and make multiple copies with a single exposure. There is. This system requires a photoreceptor with excellent so-called memory properties, which maintains photoconductivity after one image exposure, and therefore, research on imparting memory properties to photoreceptors has been actively reported. A common method for imparting memory properties is to add a memory imparting agent, such as leuco dye (Japanese Patent Application Laid-Open No. 52-4839), protonic acid (US Pat. Nos. 3,879,201 and 3,997. No. 342),
halides (U.S. Pat. No. 3,081.165), diazonium salts (Photographic
e and II! ngineering volume 26, 69
(1982)) have been proposed.

(Problems to be Solved by the Invention) Memory properties are imparted by adding the above-mentioned memory imparting agent, but in order to impart memory properties, ultraviolet light, which may deteriorate the composition of the photoconductive layer, is not used. It is difficult to put it into practical use because it requires irradiation with light from a mercury lamp, or requires long exposure using a tungsten lamp, fluorescent lamp, etc., and it is easily decomposed by light and difficult to use repeatedly, such as diazonium salts. There was a problem with that.

On the other hand, are there any known examples of photoreceptors that have an intermediate layer formed by treating a numerically so-called conductive polymer, such as a polyalkylthiophene layer, with iodine?
No. 152), this example differs from the present invention in that it is a normal electrophotographic photoreceptor, and there is almost no change in charging characteristics even after repeating the normal Carlson process, that is, a process including charging and exposure, and it has good memory properties. is the whole (not).

(Means for Solving the Problems) The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems.

That is, an object of the present invention is to provide an electrophotographic photoreceptor with efficient memory properties. This is achieved by an electrophotographic memory photoreceptor having an intermediate layer containing doped poly(3-alkylthiophene).

The present invention will be explained in detail below.

In the present invention, the conductive support may be a drum or sheet made of metal such as aluminum or brass, or an insulating plastic film or sheet made of polyester or polyimide, or paper whose surface has been treated to make it conductive. used. As a conductive treatment method, a metal layer such as aluminum, gold 9WA, or indium oxide is formed by a method such as vapor deposition or sputtering.

Examples include a method of forming a so-called transparent conductive layer such as tin oxide.

Among these, indium oxide-tin oxide system so-called I
Preference is given to supports having a transparent conductive layer called TO.

In the present invention, poly(3-alkylthiophene) doped with iodine is used for the intermediate layer. Alkyl groups include methyl group, ethyl group, propyl group,
Examples include butyl group and hexyl group.

The intermediate layer may be formed from the poly(3-alkylthiophene) alone, or may be in a mixed state with other resins. In this case, the poly(3-alkylthiophene) may contain at least It is preferable that the intermediate layer contains 10% by weight or more, preferably 20% by weight or more,
Examples of other resins that may be mixed in the intermediate layer include acrylic resin, methacrylic resin, epoxy resin, vinyl acetate resin, vinyl chloride resin, styrene resin, urethane resin, polyester resin, polycarbonate resin, polyvinyl acetal resin, Examples include cellulose derivatives and polyvinyl alcohol.

Two or more of these may be used in combination.

The poly(3-alkylthiophene) forming the intermediate layer may be formed by oxidative polymerization of the corresponding monomer directly on the conductive support, or the poly(3-alkylthiophene) synthesized by separate polymerization may be formed. If necessary, it may be mixed with other resins and formed into a film by coating.When polymerizing on a conductive support, a thin film of other resin may be applied on the support in advance to improve adhesion, etc. The polymerization may be carried out after the formation of 3-alkylthiophene in the gas phase. In this case, an oxidative polymerization catalyst may be contained in the #lI thin film in advance, and 3-alkylthiophene in the gas phase is chemically polymerized using an electrolytic polymerization method. In the method, poly(3-alkylthiophene) is formed in the thin film by a polymerization reaction.

Among the various methods mentioned above, the method for forming the intermediate layer is as follows:
From the viewpoint of film uniformity, it is preferable to form a film by directly polymerizing 3-alkylthiophene on a conductive support by electrolytic polymerization. In this case, a layer with very good film quality and a uniform surface can be obtained. Specifically, the conductive support may be used alone or
With a thin polymer film formed on the surface, it is immersed in an electrolytic solution containing 3-alkylthiophene, and a voltage is applied. As a solvent for the electrolyte, acetonitrile, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide,
Nitrobenzene propylene carbonate, pyridine, methanol, water, etc. are used, and as the support electrolyte, alkali metal salts, ammonium salts, tetraalkylammonium salts, etc. are used. The thickness of the intermediate layer is preferably 1 μl or less.

Subsequently, the formed poly(3-alkylthiophene) is doped with iodine, which is usually done by exposing it to iodine vapor.

Before the doping treatment, the formed poly(3-alkylthiophene) is washed with an appropriate solvent or dedoped in an electrolyte solution, that is, the formed poly(3-alkylthiophene) is made conductive. It is preferable to remove anions from the poly(3-alkylthiophene) in advance by immersing the conductive support in an electrolyte solution and applying electricity to the solution using the conductive support as a cathode.

The photoconductive layer of the photoreceptor of the present invention may be of any type, including known types such as a charge transfer complex type, dye-sensitized type, and functionally separated type, but a charge transfer complex type photoconductive layer is preferable. .

The charge transfer complex type photoconductive layer consists of a photoconductive charge transfer complex formed by mixing an electron donating compound and an electron accepting compound.

Examples of electron-donating compounds include polyvinylcarbazole, polyvinylanthracene, polyacenaphthylene,
Examples include photoconductive polymers such as polystyrylanthracene and polyvinylpyrene, nitrogen-containing heterocyclic compounds such as oxasialzole and pyrazoline isoxazole, and low-molecular compounds such as hydrazone compounds and triarylamines.

Examples of electron-accepting compounds include 2.4.7-)
Compounds called Lewis acids such as linitrofluorenone, 2,4,5,7-titranitrofluorenone, tetracyanoethylenetetracyanoquinodimethane, chloranil, promanil, and terephthalal malononitrile are mentioned.

Among these, it is most preferable to use a combination of polyvinylcarbazole as the electron-donating substance and 2,4,7-)linitrofluorenone as the electron-accepting substance.

A photoconductive charge transfer complex can be obtained by mixing the electron-donating compound and the electron-accepting compound. - Generally, the electron-accepting compound is used at a ratio of 0.05 to 1.3 mol, preferably 0.1 to 1.1 mol, per 1 mol of the electron donating compound (monomer unit in the case of a polymer). used.

A binder polymer plasticizer and other additives may be added to the photoconductive layer if necessary.

Polyester is used as a binder polymer.

Examples include polycarbonate, methacrylic resin, phenoxy resin, polyacrylate, polysulfone, and the like.

When the electron-donating compound is a polymer such as polyvinylcarbazole, it is not necessarily necessary to separately add a binder polymer, but it is necessary to select an appropriate polymer and add it within the range that does not impair the effect of the electron-donating compound such as polyvinylcarbazole. It is preferable to add 50 parts by weight or less to 100 parts by weight of the electron donating compound in order to improve the strength of the photoreceptor of the present invention. When the electron-donating compound is a low-molecular-weight compound, 70 to 200 parts by weight of the binder polymer is added to 100 parts by weight of the electron-donating compound;
It is preferable to add 80 to 150 parts by weight.

A photoconductive layer is formed by applying a coating liquid made of the above composition onto the intermediate layer and drying it.

As the solvent for the coating liquid, ethers such as tetrahydrofuran and dioxane, aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and esters such as ethyl acetate and butyl acetate are used. The thickness of the photoconductive layer is 5μIll to 30μm
is preferred.

A memorable latent image is formed on the photoreceptor of the present invention by charging the photoreceptor by corona discharge or the like in a dark place and then imagewise exposing it to light. The exposure amount may be any amount necessary to form a latent image.

Examples of the present invention are shown below, but the present invention is not limited by the following examples unless it exceeds the gist thereof.

Example: CITO transparent conductive layer made of indium oxide-tin oxide
) was immersed in a solution of 3-methylthiophene in 0.1M acetonitrile and tetrabutyl perchlorate added to a concentration of 0.1M, and the temperature was 0.2mA/cffl. Electrolytic polymerization was performed at a current density to form a poly(3-methylthiophene) polymer film with a thickness of 0.4 μm on ITO. This quartz glass plate, 3
- It was transferred into an electrolyte solution excluding methylthiophene and dedoped by cathodic treatment, and then the dedoped polymer film was exposed to iodine vapor to form an intermediate layer by doping with iodine. A tetrahydrofuran solution of polyvinylcarbazole and 2.4.7-)linitrofluorenone (molar ratio 1:0.5) is applied onto this intermediate layer and dried to form a photoconductive layer with a thickness of about 7 μm. Then, a photoreceptor was produced.

The electrophotographic properties of this photoreceptor were measured using an electrostatic copying paper tester (Model 5P-428 manufactured by Kawaguchi Electric Seisakusho).

Perform corona charging (applied voltage -8 kV) in the dark, and
nm monochromatic light was irradiated for 3 seconds with an exposure intensity of 0.1 mW/ci. The surface potential of the photoreceptor immediately after corona charging is Vs+
(V) The attenuation rate (%) of the surface potential after 10 seconds in the dark after the corona charging is calculated and expressed as D+ as dark attenuation, and the amount of exposure required for the surface potential to be halved during the irradiation is calculated. Sensitivity (half exposure amount.

It was calculated as E′A(1)).

Next, the process from charging to exposure described above is repeated in exactly the same way, and the surface potential immediately after charging is v3! , dark decay depth and half-reduction exposure E'4<z+ were measured.

The surface potentials VSt and vo were compared and used as an index of memory property. That is, the memory property was evaluated by the value of.

If there is no memory property, the value of ■, does not change, so it becomes -0, and if the memory property is large, the value of F, also increases, and the maximum value is 100. The measurement results are shown in Table 1.

From these results, the photoreceptor of the present invention can provide extremely large memory properties with a small exposure amount required for sensitivity measurement compared to conventional memory-prone photoreceptors, and has small dark decay and almost no fluctuation ( Moreover, the characteristics of high sensitivity were shown.This shows that it is possible to impart memory properties and obtain stable V even when corona charging is performed continuously.

This photoreceptor was kept at 100°C for 10 minutes in a dry base.
The memory property, ie the persistent photoconductivity with a single exposure, was erased.

On the other hand, when this photoreceptor was corona charged at 18kV, VS+
The voltage was -186V, the dark decay was large, and it was shown that it was not practical with negative charging.

Comparative Example 1 Completely the same as the previous example except that propylene carbonate in which tetrabutyltetrafluoroborate and pyrrole were dissolved to a concentration of 0.1 M was used as the solution for electrolytic polymerization by dipping a quartz glass plate. Electrolytic polymerization was carried out to form a polypyrrole film on the ITO film, and a photoreceptor was prepared in exactly the same manner as in the example without iodine doping treatment, and its electrophotographic properties were measured.

The measurement results are shown in Table 1.

Comparative Example 2 Completely the same as Example 1 except that an aqueous solution containing lithium tetrafluoroporate and aniline dissolved at a concentration of 0.1 M was used as the solution for electrolytic polymerization by dipping a quartz glass plate. Electrolytic polymerization is carried out in the same manner,
A polyaniline film was formed on the ITO film, and then iodine doping treatment and formation of a photoconductive layer were performed in exactly the same manner as in the example, a photoreceptor was prepared, and its electrophotographic properties were measured.

The measurement results are shown in Table 1.

Comparative Example 3 A photoreceptor identical to that produced in the above example except that it did not have a poly(3-methylthiophene) interlayer film was prepared, and its electrophotographic properties were measured in the same manner as in the above example. . The measurement results are shown in Table 1.

From the results in Table 1, all of the comparative examples have poor memory performance, low sensitivity, and large dark decay.
All of them had insufficient performance as a memory photoreceptor, indicating that the intermediate layer provided in the photoreceptor of the present invention was highly effective in imparting memory properties.

Table (Effects of the Invention) According to the present invention, by providing a specific intermediate layer, the performance of the photoreceptor is not deteriorated, and moreover, a memorable latent image can be formed with a light amount comparable to that of image exposure.

Claims (1)

[Claims] (1) A memory photoreceptor for electrophotography, comprising an intermediate layer containing poly(3-alkylthiophene) doped with iodine between a conductive support and a photoconductive layer.