JPS63206764A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To maintain high sensitivity and to prevent the occurrence of ground stain even when a sensitive body is repeatedly used at high temp. and humidity by forming an intermediate layer composed of PVA and a prescribed amt. of a metallic salt of a weak acid. CONSTITUTION:An intermediate layer 2, an electric charge generating layer 4 and an electric charge transferring layer 5 are laminated on an electrically conductive substrate 1. The layer 2 is composed of PVA as a base and <=0.5wt.% metallic salt of a weak acid. The PVA is used after alkali metallic salts of acetic acid as impurities are removed to the desired amt. or below. The weak acid is preferably carbonic acid, phosphoric acid or benzoic acid and an alkali metallic salt of the acid is desirably used. An under coat layer 6 consisting essentially of a white pigment or a light absorbing pigment and a thermosetting resin is preferably formed between the substrate 1 and the layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in an electrophotographic photoreceptor having a charge injection preventing intermediate layer.

[Prior art]

Conventionally, general electrophotographic photoreceptors in which a photosensitive layer is provided on a conductive substrate, particularly laminated electrophotographic photoreceptors in which the photosensitive layer is composed of a charge generation layer and a charge transfer layer, have been developed to have high chargeability, high sensitivity, and To provide low residual potential.

Various attempts have been made. As one example, it has been proposed to provide an intermediate layer to prevent charges having a polarity opposite to the charged charge from being injected from the conductive substrate side into the highly sensitive charge generation layer during charging.

JP-A-47-6341, JP-A-48-3544 and JP-A-4
No. 8-12034 has a cellulose nitrate resin intermediate layer,
JP 48-47344, JP 52-25638, JP 58-30757, JP 5g-63945, JP 5B-
No. 95351, No. 5g-98739, No. 60-662
No. 58 and No. 61-110153 have a polyamide resin intermediate layer, JP-A No. 48-26141 has a vinyl acetate resin intermediate layer, and JP-A-49-69332 and No. 52-
No. 10138 discloses a maleic acid resin intermediate layer, and JP-A-58-105155 discloses a 181I layer in polyvinyl alcohol. Among them, polyvinyl alcohol-based ones have an electrical resistance of 101@Ωe.
This is the most preferable intermediate layer because it has a length of about 1 m, it is easy to apply the electrophotosensitive layer in a laminated manner, and it has good film formability and it is easy to obtain a uniform coating film.

However, when a photoreceptor with a polyvinyl alcohol intermediate layer is used repeatedly under high temperature and high humidity,
Although the charging property is good, there are disadvantages in that the sensitivity decreases and residual potential accumulates, increasing the background potential and causing background smearing.

〔the purpose〕

The object of the present invention is to provide a durable electrophotographic photographic system that maintains high sensitivity even when used repeatedly not only under low temperature and low humidity conditions but also under high temperature and high humidity conditions despite having a polyvinyl alcohol intermediate layer, and which does not cause background smearing. The purpose is to provide a photoreceptor.

〔composition〕

According to the present invention, in an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially provided on a conductive substrate, the intermediate layer contains polyvinyl alcohol as a main component, and is 0.5% by weight or less with respect to the polyvinyl alcohol. Provided is an electrophotographic photoreceptor characterized by containing a metal salt of a weak acid.

The inventors of the present invention have conducted various studies with the aim of solving the drawbacks of photoreceptors having a polyvinyl alcohol intermediate layer, and have found that this kind of conventional photoreceptor, especially when used repeatedly under high temperature and high humidity conditions. It has been found that the reason why the sensitivity decreases and the residual potential accumulates and the potential of the smear area increases, resulting in smearing, lies in the impurities present in the polyvinyl alcohol.

That is, polyvinyl alcohol is generally produced by saponifying polyvinyl acetate in the presence of an alkali, and as a result, alkali metal salts such as sodium acetate are produced as by-products. Although most of these by-produced alkali metal salts of acetic acid can be removed during mother liquor separation, they cannot be completely purified. Therefore, commercially available polyvinyl alcohol usually contains about 0.8 to 2 x weight of alkali acetate. Contains metal salts.

When polyvinyl alcohol containing such an alkali metal salt of acetate is used as an intermediate layer, by repeated charging and exposure under high temperature and high humidity, the alkali metal salt moves through the intermediate layer (ion conduction) and becomes exposed to light in contact with the intermediate layer. It was found that this substance enters the layer and becomes a causative substance that lowers the light attenuation sensitivity and increases the residual potential.

As a result of further research on this point, the present inventors purified commercially available polyvinyl alcohol through various purification operations, reduced the alkali metal salt of acetic acid to less than 0.001% by weight, and then further purified polyvinyl alcohol with a weak acid. 0.5% by weight or less, preferably 0% by weight of an alkali metal salt based on polyvinyl alcohol.
．． When 1 to 0.5% by weight is added, the content of alkali ions in the intermediate layer is reduced, and therefore the amount of alkali ions mixed into the photosensitive layer is also reduced. It has been discovered that even after repeated use under high humidity, a decrease in light attenuation sensitivity and an increase in residual potential can be suppressed, and a durable electrophotographic photoreceptor with high sensitivity and no background smearing can be obtained. I have reached the point where I have completed the .

The present invention will be explained in more detail below.

In the present invention, as the main component of the intermediate layer, high-purity polyvinyl alcohol is used, in which the impurity alkali metal salt of acetic acid is separated and removed, preferably to less than 0,000% by weight, from commercially available polyvinyl alcohol.

Alkali metal salts of acetic acid such as sodium acetate in polyvinyl alcohol are difficult to remove by commonly used chemical separation methods such as distillation, extraction, separation, and filtration. It can be removed using ion separation methods such as electrodialysis or methods that separate molecules based on their differences in size.

In either method, commercially available polyvinyl alcohol may be dissolved in pure water to form a 1-10 coulometric aqueous solution, and then purified.

The ion exchange method replaces acetate ions and sodium ions with hydroxide ions and hydrogen ions using an anion exchange resin, a cation exchange resin, an anion exchange membrane, a cation exchange membrane, or an anion exchange fiber and a cation exchange fiber. Since anion exchange resins are generally commercially available with chlorine ions bound to them, the chlorine ions are replaced with hydroxide ions using, for example, a 1N aqueous solution of sodium hydroxide. Wash with pure water before use. Cation exchange resins are generally commercially available with sodium ions or hydrogen ions bound thereto. Sodium ions are replaced with hydrogen ions using, for example, a 3N aqueous solution of hydrogen chloride, and then thoroughly washed with pure water before use. In the case of a cation exchange tree jm to which hydrogen ions are bound, it is similarly treated with an aqueous hydrogen chloride solution and pure water. The ion exchange resin can be used by packing an anion exchange resin and a cation exchange resin in separate columns, or by packing them together in one column. Although it varies depending on the degree of saponification and degree of polymerization, by treating an aqueous solution with a concentration of 1% by weight to 10% by weight at a column development rate of about 0.5 to 10cc/min, a pure product with a concentration of 71m ions and sodium ions of 1100 pp or less can be obtained. A polyvinyl alcohol aqueous solution can be obtained.

The dialysis method is carried out using a dialysis membrane such as a cellophane membrane, a collodion membrane, a parchment paper, an acetyl cellulose membrane, a protein membrane, or a synthetic resin membrane. Since the solution is infiltrated, it is thoroughly washed with pure water to remove glycerin, etc., to create several dozen pores, and treated with an aqueous solution of zinc chloride or sodium hydroxide to adjust (enlarge) the pore size. Wash thoroughly before use again. An aqueous solution of polyvinyl alcohol is wrapped in the treated cellophane tube or sheet, tied with nylon thread, etc., and suspended in a tank of 50 to 100 times the volume of agitated pure water. A pure polyvinyl alcohol aqueous solution can be obtained by replacing the pure water with fresh water 4 to 5 times every 5 to 20 hours.

In the electrodialysis method, electrodes made of a material with a small ionization tendency, such as platinum, are placed between the polyvinyl alcohol aqueous solution side and the pure water side of the dialysis method described above, and the pure water side is placed between the polyvinyl alcohol side and the pure water side.
Cations (sodium ions) are generated by applying current to the electrodes.
Next, replace the pure water tank with a new one, use the polyvinyl alcohol side as the e electrode and the pure water side as the Φ electrode, and apply current to remove anions (acetate ions) and prepare a pure polyvinyl alcohol aqueous solution. This is the way to get it.

In any case, in both of the above methods using a dialysis membrane, water enters due to osmotic pressure, so it is necessary to adjust the solid content concentration of polyvinyl alcohol after treatment.

Furthermore, the intermediate layer of the present invention contains a weak acid of 0.5% by weight or less, preferably 0.1 to 0.5% by weight based on the polyvinyl alcohol, in order to lower the electrical resistance under low humidity. Contain metal salt.

Weak acids include not only carbonic acid and inorganic acids such as phosphoric acid, but also
Carboxylic acids such as benzoic acid, phthalic acid, lauric acid, and stearic acid can be used, but carbonic acid, phosphoric acid, and benzoic acid are particularly preferably used from the viewpoint of effectiveness.

These metal salts of weak acids are not particularly limited, but it is preferable to use alkali metals such as lithium, sodium, potassium, etc.The amount of metal salts of weak acids to be used is 0.5% by weight or less based on polyvinyl alcohol. , preferably 0.1~
It is 0.5%.

When the amount used decreases o, sang, the light attenuation sensitivity decreases as in conventional products, and background smearing becomes noticeable due to an increase in residual potential.

The basic structure of the photoreceptor of the present invention is as shown in FIG. 1, in which a charge injection preventing intermediate layer 2 and a single-layer photosensitive layer 3 are provided on a conductive substrate 1, and as shown in FIG. A laminated photosensitive layer 3' consisting of a charge injection preventing intermediate layer 2, a mold generation layer 4, and a charge transfer layer 5 is provided on a conductive substrate 1.

In the present invention, in order to prevent light interference required for a photoreceptor for a printer using a laser light source, a conductive substrate is used as shown in the 3rd to 41st thresholds for both a single layer type photoreceptor and a laminated type photoreceptor, respectively. A light-scattering or light-absorbing subbing layer 6 can be inserted between the charge injection preventing intermediate layer 2 and the charge injection preventing intermediate layer 2.

Next, each constituent material used in the present invention will be explained.

The purpose of the conductive substrate is to supply charges of opposite polarity to the charged charges to the substrate side.

A material having an electrical resistance of 10' ΩC or less and capable of withstanding the conditions for forming the intermediate layer, charge generation and charge transfer layers can be used. Examples of these are AQ, Ni
, vacuum evaporation and sputtering on the surfaces of electrically conductive metals and alloys such as Cr, Zn, and stainless steel, inorganic insulating substances such as glass and ceramics, and organic insulating substances such as polyester, polyimide, phenolic resin, nylon resin, and paper. , AQ by spray painting, etc.
, Ni, Cr, Zn, stainless steel, carbon, 5n0
Examples include those coated with an electrically conductive material such as No. 2, In2O, etc., and subjected to conductive treatment.

The charge injection preventing intermediate layer prevents charge injection from the conductive substrate to the photosensitive layer when the photoreceptor is charged, and maintains the chargeability, and when the photoreceptor is exposed, it protects one of the pairs of charges generated in the photosensitive layer, that is, the side of the conductive substrate. It has the effect of moving charges of opposite polarity to the charges blocked by the conductive substrate toward the conductive substrate. This is especially necessary when the photosensitive layer has high sensitivity since the charging property of the photosensitive layer becomes poor. This intermediate layer is 0.5% by weight obtained as described above.
It is formed by applying a polyvinyl alcohol solution containing the following metal salt of a weak acid onto a substrate or a subbing layer by a method such as a spray coating method, a blade coating method, a dip coating method, or a roll coating method. A suitable thickness is 0.2 to 2 μm.

The photosensitive layer in the present invention may be either a single layer type as shown in FIG. 1 or a laminated type as shown in FIG.

A single-layer type photosensitive layer is a layer that has both charge generation and charge transfer functions in one layer, and is a layer whose purpose is to form a charge latent image by imagewise exposure.

This type of photosensitive layer contains dye-sensitized photoconductive powder such as zinc oxide, titanium oxide, zinc sulfide, amorphous silicon powder, crystalline selenium powder, phthalocyanine pigment, azo pigment, and binder resin. Further, if necessary, it is formed on the intermediate layer together with a charge transfer material to be described later. The binder resin used is the same as that used in the laminated photosensitive layer described later. Furthermore, a single-layer type photosensitive layer in which a charge transporting substance is added to a eutectic complex formed from a pyrylium dye and a bisphenol A polycarbonate can also be used. The appropriate thickness is 5 to 30 μI.

In addition, the charge generation layer in the laminated photosensitive layer is a layer whose purpose is to generate and separate charges by one image exposure. The organic pigments include phthalocyanine pigments, disazo pigments, trisazo pigments, perylene pigments, squalic basic dyes, azulenium salt dyes, and quinone condensed polycyclic compounds. Specific examples of disazo pigments and trisazo pigments are shown below.

Salmon family 1 - 1 per person salmon family No. 1 - 1 koshi 11 salmon family 1
- One piece, one face'' L outfit A Salmon family 1A Group 1nu - - Kom face] Lnu A face] L outfit - Kou face JL! xi A face” instrumentation
-11 to 11 with 111 face Jt
AILLI! 111 - 11 to 11 Salmonidae 1 - 11 faces to 11 a - 111 faces to 11] L packaging
--Koshi--QC, H3 These organic dyes and pigments are used after being dispersed in a resin or without a resin by adding an organic solvent and using a method such as a ball mill method. Examples of resins (binder) for dispersing these organic dyes and pigments include polyamide, polyurethane, polyester,
Condensation resins such as epoxy resins, polycarbonates, and polyethers, as well as polystyrene, polyacrylates, polymethacrylates, polyN vinylcarbazole, polyvinyl butyral, and styrene-butadiene copolymers.

Examples include polymers and copolymers such as styrene-acrylonitrile copolymers, which require insulation and adhesive properties. The charge generation layer has the above dyes and pigments dispersed therein.

A film is formed on the intermediate layer in the same manner and dried to a film thickness of O, O.
A charge generation layer of S μl to several μm is formed. The content of the organic dye and pigment is preferably 60% by weight and 100% by weight.

When crystalline selenium or arsenic selenide alloy powder is used, it is used in combination with a charge-transfer binder and/or a charge-transfer organic compound. Such charge transfer substances include polyvinylcarbazole and its derivatives (for example, those having a halogen such as chlorine or bromine, or a substituent such as a methyl group or an amino group in the carbazole skeleton), polyvinylpyrene, oxadiazole, pyrazoline, hydrazone, diarylmethane.

α = Nitrogen-containing compounds such as phenylstilbene, triphenylamine compounds, diarylmethane compounds, etc., but polyvinylcarbazole and its derivatives are particularly preferred, and these substances may be used as a mixture. When used, it is preferable to add other charge-transferable organic compounds to polyvinylcarbazole and its derivatives.

Furthermore, a binder resin can be used in combination with an organic pigment if necessary for the purpose of improving adhesiveness, flexibility, etc.

The content of this type of charge generating substance is suitably 30 to 90% by weight of the entire layer. Further, when a charge generating substance is used, the thickness of the charge generating layer is suitably 0.2 to 5 μm.

The purpose of the charge transfer layer provided on the charge generation layer is to retain the charged charges on its surface, and also to move the charges generated and separated in the charge generation layer by exposure and combine them with the held charges. This is the layer where In order to achieve the purpose of retaining electrical charges, high electrical resistance is required.
In addition, in order to achieve the purpose of obtaining a high surface potential using the retained charges, it is required that the dielectric constant be small and the charge mobility be good. In order to satisfy these requirements.

An organic charge transfer layer containing an organic charge transfer substance as an active ingredient is used. Examples of the organic charge transfer substance include poly-N-vinylcarbazole compounds, pyrazoline compounds, α-phenylstyrene bene compounds, hydrazone compounds, diarylmethane compounds, triphenylamine compounds, divinylbenzene compounds, Conventionally known compounds such as fluorine compounds, anthracene compounds, oxadiazole compounds, and diaminocarbazole compounds can be used.

These organic charge transfer substances other than polymers such as polyvinylcarbazole are used by being blended with the same resin as shown as the binder for the charge generation layer described above. However, it is not necessary that the resin used in the charge generation layer and the resin used in the charge transfer layer be the same, and a plasticizer may be added to them if necessary. These plasticizers include
Examples include halogenated paraffins, dimethylnaphthalene, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and polymers and copolymers of polyester. A charge transfer substance, the binder resin, and silicone oil (as a leveling agent during film formation) are dissolved in an organic solvent, and a film is formed and dried in the same manner as the intermediate layer and the charge generation layer.

A charge transfer layer having a thickness of 5 to 100 μm is formed on the charge generation layer. The ratio of ff1 cargo transport substance to resin binder is 2/
8 to 8/2 weight ratio, and the amount of silicone oil to resin binder is 0.001% by weight to 1% by weight.

As described above, the light-scattering subbing layer and the light-absorbing subbing layer are layers intended to prevent light interference in a photoreceptor for a printer. The light-scattering undercoat layer is made of, for example, conductive powder such as tin oxide or antimony oxide and zinc oxide.

It is composed of a white pigment such as zinc sulfide or titanium oxide dispersed in a thermosetting resin as shown below, and the light-absorbing subbing layer is composed of a conductive light-absorbing pigment such as carbon, various metals, etc. It is also constructed by dispersing a light-absorbing organic pigment in a similar thermosetting resin. The thermosetting resin used here is, for example,
Active hydrogen (-011 group.

-NH2Jls, -N11 groups, etc.) and/or a compound containing a plurality of epoxy groups are thermally polymerized. Examples of compounds containing multiple active hydrogens include acrylics containing active hydrogen such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene gellicol, and hydroxyethyl methacrylate group. Examples of compounds containing multiple isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and their prepolymers, and examples of compounds containing multiple epoxy groups include bisphenol A type. Examples include epoxy resin, etc. In any case, the light-scattering or light-absorbing undercoat layer is formed by coating a liquid in which the above components are dissolved or dispersed on the substrate and thermally polymerizing it at 50 to 200°C. be done. Note that the thickness of this undercoat layer is suitably 1 to 10 μm. Further, the weight ratio of the conductive powder, the white pigment, and the thermosetting resin is suitably 2 to 6/1 to 572 to 6;
Moreover, the weight ratio of the light-absorbing pigment and the thermosetting resin is 4 to 4.
9/1 to 6 is appropriate.

〔effect〕

The electrophotographic photoreceptor of the present invention has as a main component of the intermediate layer:
By using polyvinyl alcohol and containing a metal salt of a weak acid with a weight of 0.5 times less than the polyvinyl alcohol, it maintains high sensitivity even when used repeatedly not only at low temperatures and low humidity, but also at high temperatures and high humidity. To provide a copy image that is maintained and does not cause background stains.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 An 8-weight jXI kg pure aqueous solution of commercially available polyvinyl alcohol (manufactured by Kanto Kagaku Co., Ltd.; Polyvinyl Alcohol 12000) was passed through an ion exchange column to create an approximately 8% by weight aqueous high-purity polyvinyl alcohol solution having the following composition. .

The ion exchange column used DOWEX MSA-1 manufactured by Dow Chemical Company as an anion exchange resin and DOWEX 50W as a cation exchange resin, and the column development rate was 1 cc/min.

Therefore, the polyvinyl alcohol before treatment contains 1.1% by weight of sodium acetate, but the high purity polyvinyl alcohol after treatment contains 0.0005% by weight or less of sodium acetate and 0.1% by weight. It is understood that O3ff contains am of 1 m% or less.

Furthermore, the results of measuring the content of acetyl groups using gas chromatography revealed that the degree of saponification of polyvinyl alcohol did not change before and after the treatment.

Next, 92 parts by weight of methanol was added to 100 parts by weight of this high-purity polyvinyl alcohol, and 0.125 parts by weight of sodium carbonate was added to the polyvinyl alcohol to prepare an intermediate layer coating liquid. Next, this intermediate layer coating solution was washed with perchloren vapor to form a 0.3-thick layer A.
Dip coating on Q board and drying at 130℃ for 10 minutes to give a coating of approx.
A very thick intermediate layer was formed.

On the other hand, 172 volumes of stainless steel poles with a diameter of 1 cm, 400 g of cyclohexanone, and 25 g of the azo pigment Not were placed in a glass pot with a diameter of 15 cm and mixed for 48 hours. Further, 408 g of cyclohexanone was added and mixed for another 24 hours, and then 700 g of tetrahydrofuran was added dropwise to 700 g of the dispersion solution taken out while stirring to prepare a coating liquid for a charge generation layer.

Next, this coating liquid is dip coated onto the intermediate layer.

It was dried at 130° C. for 10 minutes to form a charge generation layer with a thickness of about 0.1 μm.

Subsequently, a charge transfer layer coating solution having the following formulation was applied by dip coating onto this charge generation layer, and dried at 130°C for 1 hour to form a layer of about 21 μm.
A thick charge transfer layer was formed to produce an electrophotographic photoreceptor of Example 1.

[Coating liquid for charge transfer layer]

Silicone oil (trade name, F2O: Shin-Etsu Silicone ■) 0.0002 parts by weight Tetrahydrofuran 80 parts by weight Example 2 In Example 1, the amount of sodium carbonate added to the intermediate layer coating liquid was changed to 0.37575 parts by weight. An electrophotographic photoreceptor of Example 2 was prepared in the same manner as Example 1 except for the above.

Example 3 An electrophotographic photoreceptor of Example 3 was prepared in the same manner as in Example 2 except that sodium carbonate in the intermediate layer coating solution was replaced with lithium carbonate.

Comparative Example 1 An electrophotographic photoreceptor of Comparative Example 1 was prepared in the same manner as in Example 1 except that the amount of sodium carbonate added to the intermediate layer coating solution was limited to 1.00% by weight.

Comparative Example 2 Example 1 except that the intermediate layer coating liquid was replaced with a mixture of 100 parts by weight of an 8-by-2 aqueous solution of the untreated commercially available polyvinyl alcohol and 92 parts by weight of methanol.
An electrophotographic photoreceptor of Comparative Example 2 was prepared in the same manner as above.

Comparative Example 3 Same as Example 1 except that the intermediate layer is not provided.
An electrophotographic photoreceptor of Comparative Example 3 was prepared in the same manner as described above.

Example 4 An electrophotographic photoreceptor of Example 4 was prepared in the same manner as in Example 1 except that sodium carbonate in the intermediate layer coating solution was replaced with sodium phosphate.

Example 5 An electrophotographic photoreceptor of Example 5 was prepared in the same manner as in Example 2 except that sodium carbonate in the intermediate layer coating solution was replaced with sodium phosphate.

Example 6 An electrophotographic photoreceptor of Example 6 was prepared in the same manner as in Example 5 except that lithium phosphate was used instead of sodium phosphate in the intermediate layer coating solution.

Comparative Example 4 An electrophotographic photoreceptor of Comparative Example 4 was prepared in the same manner as in Example 4, except that the amount of sodium phosphate added to the intermediate layer coating liquid was changed to 1.00% by weight. did.

Example 7 An electrophotographic photoreceptor of Example 7 was prepared in the same manner as in Example 1 except that sodium carbonate in the intermediate layer coating solution was replaced with sodium benzoate.

Example 8 An electrophotographic photoreceptor of Example 8 was prepared in the same manner as in Example 2, except that sodium carbonate in the intermediate layer coating solution was replaced with sodium benzoate.

Example 9 An electrophotographic photoreceptor of Example 9 was prepared in the same manner as in Example 8 except that lithium benzoate was used instead of sodium benzoate in the intermediate layer coating solution.

Comparative Example 5 An electrophotographic photoreceptor of Comparative Example 5 was prepared in the same manner as in Example 7, except that the amount of sodium benzoate added to the intermediate layer coating solution was changed to 1.00% by weight. did.

Each photoconductor prepared as described above was heated at low humidity (10℃,
15%) and high temperature and high humidity (30°C, 90%) measurement environments. Commercially available electrostatic copying paper test equipment! t (Kawaguchi Electric Works 11
elsP428 type) to generate a 2-6 kV corona discharge.
After charging for 0 seconds, measure the surface potential Vm of the photoreceptor, and then measure the surface potential Vp after leaving it in a dark place for 20 seconds.
o was set as 1. Next, tungsten lamp light was irradiated so that the illuminance on the photoreceptor surface was 4.5 lux.
The exposure amount E4 until po reached 172 and the residual potential Vr after irradiation for 30 seconds were measured. In addition, in order to understand the repeated fatigue characteristics, charging at -7.5 kV and exposure at 50 lux was repeated for 1 hour using the above device, and V's and V' after fatigue were measured.
po-E'h and V'r were measured. The measurement results under low temperature and low humidity are shown in Table 1, and the results under high temperature and high humidity are shown in Table 2.

Example 10 φ1 of 1/2:lf volume in φ9C11 Tsugara pot
cII+ alumina sintered balls, 8 g of fine tin oxide powder containing 10 weight x antimony oxide, 5 g of titanium oxide powder, and 68 g of methyl ethyl ketone solution of butyral resin (Sekisui Kagaku Co., Ltd. [IL-1) with a solid content concentration of 12 years]
and mixed for 72 hours, then methyl ethyl ketone 4
To 80 g of the pigment dispersion taken out, 8 g of tolylene diisocyanate in 20% by weight methyl ethyl ketone solution was added and stirred to obtain a light-scattering undercoat layer coating solution. . The above coating solution was applied by dip coating onto an AQ substrate in the same manner as in Example 1, and
A light-scattering undercoat layer having a thickness of about 3 μm was formed by heating and curing for a period of time.

Next, the coating liquid for the intermediate layer used in Example 2 is applied onto this undercoat layer to form an intermediate layer, and the coating liquid for the charge generating layer shown below is applied to the coating liquid for the charge generating layer of Example 1. A photoreceptor of Example 10 was prepared in the same manner as Example 1 except that the coating solution was used instead of the coating liquid.

[Coating liquid for charge generation layer]

1/2 volume φ1cI1 in a φ15cm glass pot
1 agate balls, 400 g of the following resin liquid, and 25 g of the azo pigment N047 were added and mixed for 48 hours. Further, 580 g of the following resin solution was added and mixed for a further 24 hours, and then 710 g of methyl ethyl ketone was added dropwise to 950 g of the dispersion solution taken out while stirring to obtain a charge generation layer coating solution.

(!M fat liquid) Cyclohexanone 970 parts by weight Comparative Example 6 Comparative Example 6 was carried out in the same manner as in Example 10, except that the intermediate layer coating liquid in Example 10 was replaced with that used in Comparative Example 1. An electrophotographic photoreceptor was prepared.

Comparative Example 7 Example 1 except that the intermediate layer is not provided in Example IO
An electrophotographic photoreceptor of Comparative Example 7 was prepared in the same manner as O.

Example 11 An electrophotographic photoreceptor of Example 11 was prepared in the same manner as in Example 1O, except that the intermediate layer coating liquid was replaced with that used in Example 5.

Comparative Example 8 An electrophotographic photoreceptor of Comparative Example 8 was prepared in the same manner as in Example 1O, except that the intermediate layer coating liquid was replaced with that used in Comparative Example 4.

Example 12 An electrophotographic photoreceptor of Example 12 was prepared in the same manner as in Example 10, except that the intermediate layer coating liquid was replaced with that used in Example 8.

Comparative Example 9 An electrophotographic photoreceptor was prepared in the same manner as in Example 10 in Example IO, except that the intermediate layer coating liquid was replaced with that used in Comparative Example 5.

Comparative Example 10 The electrophotographic photoreceptor of Comparative Example 1o was prepared in the same manner as in Example 10, except that the following was used as the intermediate layer coating liquid and the thickness of the intermediate layer was 1 μm. It was created.

[Coating liquid for intermediate layer]

Polyamide copolymer (Toshisha jllcM8000) 4
Foot warming part Methyl alcohol 38 parts by weight Butyl alcohol 58 parts by weight Comparative Example 11 Electrophotographic photoreceptor of Comparative Example 11 was prepared in the same manner as Comparative Example 1O, except that in Comparative Example IO, the thickness of the intermediate layer was changed to 0.4 μm. It was created.

The electrical characteristics of each of the photoreceptors prepared as described above were measured in the same manner as in Example 1 under low temperature and low humidity conditions and under high temperature and high humidity conditions.

The measurement results under low temperature and low humidity are shown in Table 3, and the measurement results under high temperature and high humidity are shown in Table 4.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views of an electrophotographic photoreceptor according to the present invention. 1: Conductive substrate 2: Charge injection prevention intermediate layer 3: Single layer type photosensitive layer 3': Laminated type photosensitive layer 4: Charge generation layer 5: Charge transfer layer

Claims (3)

[Claims] (1) In an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially provided on a conductive substrate, the intermediate layer contains polyvinyl alcohol as a main component, and contains 0.5% by weight or less of a weak acid based on the polyvinyl alcohol. An electrophotographic photoreceptor characterized by containing a metal salt. (2) The electrophotographic photoreceptor according to claim 1, wherein the weak acid is at least one selected from carbonic acid, phosphoric acid, and benzoic acid. (3) Claims in which a light-scattering or light-absorbing subbing layer containing a white pigment or a light-absorbing pigment and a thermosetting resin as main components is further provided between the conductive substrate and the intermediate layer. 2. The electrophotographic photoreceptor according to item 1.