JPH01572A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 Various attempts have been made to provide low residual potential. As one of these, it has been proposed to provide an intermediate layer to prevent charges of opposite polarity from the charged charge from being injected from the conductive substrate side into the highly sensitive charge generation layer during charging. For example, JP-A-47-6341, JP-A-48-3544, and JP-A-48-12034 have cellulose nitrate resin intermediate layers;
No. 58-30757, No. 58-63945, No. 58
-95351, 58-98739, 60-66
No. 258 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 No. 49-69332 and No. 52 have a vinyl acetate resin intermediate layer.
No. 10138 discloses a maleic acid resin intermediate layer, and JP-A-58-105155 discloses a polyvinyl alcohol intermediate layer.

However, when a conventionally known photoreceptor with an intermediate layer is used repeatedly, the charging potential rises slowly and the charging characteristics deteriorate, resulting in a decrease in image density, and especially in the case of reversal development, the image density decreases. The problem was that it caused stains.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that maintains high sensitivity even after repeated use, does not deteriorate its charging characteristics, and therefore provides good images without a decrease in image density or background smudge. .

〔composition〕

According to the present invention, there is provided an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially provided on a conductive substrate, wherein the intermediate layer contains an aliphatic alcohol. Ru.

The electrophotographic photoreceptor of the present invention has as a main component of the intermediate layer:
Since at least an aliphatic alcohol is used, the charging characteristics do not deteriorate even when used repeatedly, unlike conventional products, so that a clear copy image is provided without a decrease in image density or background smudge.

The present invention will be explained in detail below.

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 photoreceptor M3 are provided on a conductive substrate L, and as shown in FIG. A laminated photosensitive layer 3' comprising a charge injection preventing intermediate layer 2, a charge generation layer 4, and a charge transfer layer 5 is provided on a conductive substrate 1.

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.

It is possible to use a material that has an electrical resistance of 10 QΩcm or less and can withstand the film forming conditions of the intermediate layer, charge generation, and charge transfer layer. Examples of these are AQ%Nj, .
Electrically conductive metals and alloys such as Cr%Zn and stainless steel, inorganic insulating materials such as glass and ceramics, and polyester and polyimide.

Electrically conductive materials such as AQ, Ni, Cr, Zn, stainless steel, carbon, SnO, In2O, etc. are coated on the surface of organic insulating materials such as phenol resin, nylon resin, and paper by methods such as vacuum evaporation, sputtering, and spray painting. Examples include those coated with a conductive substance and subjected to conductive treatment.

The charge injection preventing intermediate layer prevents charge injection from the conductive substrate to the photosensitive layer when the photoconductor is charged at 4F, thereby maintaining charging properties, and also protects one side of the charge generated in the photosensitive layer during exposure of the photoconductor, 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.

In the present invention, an aliphatic alcohol is used in the intermediate layer.

As the aliphatic alcohol, not only aliphatic monohydric alcohols but also aliphatic polyhydric alcohols can be used.

As the higher aliphatic alcohol, those having 5 or more carbon atoms, preferably 12 to 25 carbon atoms are used, and specific examples of these compounds include n-amyl alcohol, isoamyl alcohol, and 2-methyl-1-butanol. , n-hexyl alcohol, n-heptyl alcohol, pentamethyl alcohol, n-octyl alcohol, n-nonyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, n-eicosyl alcohol, n-docosanol, ceryl alcohol, Alcohols such as n-ophtacosyl alcohol, n-triacontyl alcohol, and mericyl alcohol are exemplified, but in the present invention, in particular, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, n-eicosyl alcohol, It is desirable to use a higher aliphatic alcohol having 12 or more carbon atoms such as n-docosanol and ceryl alcohol.

As the aliphatic dihydric alcohol, those having 2 or more carbon atoms, preferably 3 to 20 carbon atoms are used, and specific examples of these compounds include ethylene glycol, propylene glycol, ethyl ethylene glycol, and 2,3-butanediol. , 2-methyl-1,2-propanediol, ■,
2-bentanediol, 2,3-bentanediol, t
hreo-2,3-bentanediol, erythro
-2,3-bentanediol, 3-methyl-1,2-butanediol, 2-methyl-1,2-butanediol,
2-methyl-2,3-butanediol, pinacol, trimethine glycol, 1-3butanediol, 2.4
-bentanediol, 2-methyl-2,4-butanediol, 2-methyl-2,4-bentanediol, 2,4
-dimethyl-2,4-bentanediol, hexamethyltrimethylene glycol, 2,2-dimethyltrimethylene glycol, 2,2-dimethyl-1,3-butanediol, 2,2-dimethyl-1,3-bentanediol ,
Tetramethylene glycol, 2,2.4-trimethyl-1,3-bentanediol, γ-pentylene gelicol, 2-methyl-2,5-bentanediol, 3-methyl-2,5-bentanediol, 1-. 4-hexanediol, 2,5-hexanediol 1.2,5-dimethyl-2,5-hexanediol, pentamethylene glycol, 1,5-hexanediol, hexamethylene glycol, 1,7-hebutanediol, 1 , 8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-
Dodecanediol, 1,13-tridecanediol, 1
, 14-tetradecanediol, 1,12-octadecanediol, 1,18-octadecanediol and the like.

Although the intermediate layer of the present invention has an aliphatic alcohol as its main component, resins commonly used in this type of intermediate layer may be used in combination, if necessary.

Examples of such resins include thermoplastic resins such as polyester, polycarbonate, polyvinyl butyral, polyamide, polystyrene, polyurethane, polypropylene, polyacrylate, and polyvinyl chloride, as well as thermosetting resins such as phenolic resin, melamine resin, and epoxy resin. Examples include photocurable resins and photocurable resins. Further, conductive powder such as 5nO7, Sb, 01, etc. and/or white pigment such as ZnO, ZnS, TiO2, etc. can also be contained in the intermediate layer. The intermediate layer is formed on the conductive substrate by roll coating, dip coating, spray coating, blade coating, etc., and is dried or cured at 50 to 200°C to form a film with a thickness of 0.05 to 10 μm. , preferably 0.2~
The film is 2 μm thick.

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

Further, the charge generation layer in the laminated photosensitive layer is a layer whose purpose is to generate and separate charges by imagewise exposure. In the present invention, the charge generation layer uses organic dyes and pigments, crystalline selenium, or arsenic selenide as a charge generation substance, and examples of the organic pigments include phthalocyanine pigments, disazo pigments, 1-helisazo pigments, and perylene pigments. , squalic salt dyes, azulenium salt dyes, quinone fused polycyclic compounds, and the like. Specific examples of disazo pigments and trisazo pigments are shown below.

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---Δ --- These organic dyes and pigments are used by adding an organic solvent in a resin or without a resin and dispersing them by methods such as a ball mill, a sand mill, a three-roll mill, an attritor, and an ultrasonic method. A resin that disperses these organic dyes and pigments (
Examples of binders include polyamide, polyurethane,
Condensation resins such as polyester, epoxy resin, polycarbonate, polyether, and polymers and copolymers such as polystyrene, polyacrylate, polymethacrylate, polyN vinyl carbazole, polyvinyl butyral, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, etc. Examples include polymers, which require insulation and adhesive properties. Disperse using the same dispersion method as above, form a film on the intermediate layer using the same method as the intermediate layer, and dry it to a film thickness of 0.05 μm.
A charge generation layer with a thickness of m to several μI is formed.

The content of the organic dye and pigment is preferably 60% by weight to 100% by weight.

When crystalline selenium or arsenic selenide alloy powder is used, it is used in combination with a charge-transferable binder and/or a charge-transferable 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, bira, Nitrogen-containing compounds and diarylmethane compounds such as purine, hydrazone, diarylmethane, α-phenylstilbene, and triphenylamine compounds are available, and polyvinylcarbazole and its derivatives are particularly preferred. Alternatively, a mixture of these substances may be used. Even when used in combination, 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, the retained electrical charge increases the surface potential by 1! ), 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. Furthermore, a plasticizer is added to these as necessary. Examples of such plasticizers include halogenated paraffins, dimethylnaphthalene, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and polymers and copolymers such as polyester. The charge transfer substance and the binder resin (
Silicone oil (as a leveling agent during film formation) is dissolved in an organic solvent, and the film is formed and dried in the same manner as the intermediate layer and charge generation layer to form a charge transfer layer of 5 μm to 100 μm. Form on the layer. The charge transfer material to resin binder ratio is from 2/8 to 872% by weight, and the amount of silicone oil to resin binder is from o, oot% to 1% by weight.
Heavy fi1%.

[Effect] The electrophotographic photoreceptor of the present invention contains, as the main component of the intermediate layer,
Since the aliphatic alcohol is used, the charging characteristics do not deteriorate even after repeated use, so a clear copy image is produced without a decrease in image density or background smudge.

〔Example〕

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

Example 1 [Coating liquid for intermediate layer] n-stearyl alcohol 4 parts by weight Nylon resin (manufactured by Toshi ■, CM-8000) 4 n-methanol 60 Butanol
32〃The above mixture was mixed to prepare a coating liquid for an intermediate layer.

[Coating liquid for charge generation layer]

φ] A volume of 172 φ in a 5 cm glass pot
1c111 stainless steel pole, 400 g of cyclohexanone, and 25 g of the azo pigment Nol were added and mixed for 48 hours. After 400 g of cyclohexanone was added and mixed for another 24 hours, 800 g of methyl ethyl ketone was added dropwise to the 800K dispersion solution taken out while stirring to obtain a charge generation layer coating solution.

[Coating liquid for charge transfer Jfn]

Tetrahydrofuran 80 parts by weight Next, a 100 μm thick PET film without AQ deposition (Toshi
The coating solution for the intermediate layer was applied onto the surface of the product (manufactured by Lumirror) using a doctor blade, and dried by heating at 120° C. for 10 minutes to form an intermediate layer having a thickness of 1 μm. Next, the charge generation layer coating liquid was applied onto this intermediate layer using a blade, and 12
A charge generation layer having a thickness of 0.1 μm was formed by heating and drying at 0°C for 10 minutes, and the charge transfer layer coating solution was applied thereon using a blade, followed by heating and drying at 120°C for 20 minutes. 1
A charge transfer layer having a thickness of 20 .mu.m was formed to produce an electrophotographic photoreceptor of Example 1.

Comparative Example 1 An electrophotographic photoreceptor of Comparative Example 1 was prepared in the same manner as in Example 1 except that n-stearyl alcohol was removed from the intermediate layer coating solution of Example 1.

Example 2 An electrophotographic photoreceptor of Example 2 was prepared in the same manner as in Example 1 except that the intermediate layer coating liquid was replaced with the one shown below.

[Coating liquid for intermediate layer]

n-stearyl alcohol 4 parts by weight Polyvinyl alcohol (manufactured by Denki Kagaku Kogyo ■, Poval B-24) 4 n methanol 41 water
41 Comparative Example 2 An electrophotographic photoreceptor of Comparative Example 2 was prepared in the same manner as in Example 2 except that n-stearyl alcohol was removed from the intermediate layer coating solution of Example 2.

Example 3 An electrophotographic photoreceptor of Example 3 was prepared in the same manner as in Example 1, except that the intermediate layer coating liquid was replaced with the one shown below.

[Coating liquid for intermediate layer]

n-Docosanol 4 parts by weight Nylon resin (manufactured by Toshi@, CM-8000) 4″
Methanol 60 Butanol 32I! Example 4 An electrophotographic photoreceptor of Example 4 was prepared in the same manner as in Example 1, except that the charge transfer substance was replaced with the following.

Comparative Example 3 An electrophotographic photoreceptor of Comparative Example 3 was prepared in the same manner as in Example 4 except that n-stearyl alcohol was removed from the intermediate layer coating solution of Example 4.

Example 5 n-stearyl alcohol 5 parts by weight
M/Resin (Toshi@*, CM-8000) 5 n
Tin oxide fine powder 5 Titanium oxide powder 3 n methanol
The solution consisting of 40% of the dispersion was dispersed in a ball mill for 72 hours, then diluted with a mixed solvent of methanol/butanol (20/30 parts by weight), and treated again in a ball mill for 48 hours.

An electrophotographic photoreceptor of Example 5 was prepared in the same manner as Example 1 except that this liquid was used as the intermediate layer coating liquid.

Example 6 n-stearyl alcohol 48 parts by weight Tin oxide fine powder 48 Tolylene diisocyanate 14.5 LL cyclohexanone
552 parts by weight methyl ethyl ketone
After coating the intermediate layer, a solution consisting of 130 th was used as the coating solution for the intermediate layer.

Example 1 except that heat treatment was performed at 130°C for 1 hour.
An electrophotographic photoreceptor of Example 6 was prepared in the same manner as described above.

Example 7 An electrophotographic photoreceptor of Example 7 was prepared in the same manner as in Example 1 except that n-stearyl alcohol in the intermediate layer coating solution was replaced with 1,12-dodecanediol.

Example 8 An electrophotographic photoreceptor of Example 8 was prepared in the same manner as in Example 1 except that the intermediate layer coating liquid in Example 7 was replaced with the one shown below.

[Coating liquid for intermediate layer]

1.12-Dodecanediol 4 parts by weight Methanol 41 Water
41 Example 9 An electrophotographic photoreceptor of Example 9 was prepared in the same manner as in Example 7, except that the intermediate layer coating liquid was replaced with the one shown below.

[Coating liquid for intermediate layer]

Propylene glycol 4 parts by weight Nylon resin (manufactured by Toshi@, CM-8000) 4 II methanol 60 Butanol
32 Example 10 An electrophotographic photoreceptor of Example 10 was prepared in the same manner as in Example 7, except that the charge transfer substance was replaced with the following.

Example 11 1.12-Dodecanediol 5 parts by weight Nylon resin (manufactured by Toshi ■, CM-8000) 5
n Tin oxide fine powder 5 Titanium oxide powder 3 Methanol
A liquid consisting of 40〃 is milled with a ball mill to 72
Time dispersed primary methanol/butanol (20/30
The mixture was diluted with a mixed solvent (parts by weight) and treated again in a ball mill for 48 hours.

An electrophotographic photoreceptor of Example 11 was prepared in the same manner as in Example 7 except that this liquid was used as the coating liquid for the intermediate layer.

Example 12 1.12-Dodecanediol 48 parts by weight Tolylene diisocyanate 14.5 n Tin oxide fine powder 48 Cyclohexanone 552 parts by weight Methyl ethyl ketone
The electrophotographic photoreceptor of Example 12 was prepared in the same manner as in Example 1, except that a solution consisting of 130 〃 was used as a coating solution for the intermediate layer, and after coating the intermediate layer, heat treatment was performed at 130° C. for 1 hour. Created.

The electrophotographic properties of the electrophotographic photoreceptor prepared as described above were evaluated in the following manner using an electrostatic copying paper tester (SP42g type manufactured by Kawaguchi Electric Seisakusho).

First, corona charging of -6KV was carried out for 20 seconds, and then the surface potential became 1800V after being left in a dark place.
4.51 ux of tungsten light was irradiated, and the surface potential V2.2 seconds after the start of charging at this time. The exposure amount required for the surface potential to become 1400V during light irradiation is 5 (lux 5ec)
was measured. Also, after this, the color temperature of 2856 is applied to the photoreceptor.
A tungsten light of K was irradiated at 1o00001ux see, and the 41F electric potential v2' and the exposure amount S' were determined in the same manner as above.

Table 1 Example 13 The same intermediate layer coating solution as in Example 1 was dip-coated on an AQ drum with a wall thickness of 3 mm, 80φ x 340m1, and 130
Heat drying was performed at ℃ for 20 minutes to form an intermediate layer having a thickness of 1 μm. Further, a charge generation layer coating liquid similar to that in Example 1 was applied by dip coating on this, and the resultant was heated and dried at 130° C. for 20 minutes to form a charge generation layer of 0.1 μm. Furthermore, a charge transfer layer coating solution was dip-coated thereon and dried by heating at 130° C. for 30 minutes to obtain a charge transfer layer with a thickness of 20 μm.

F-4060 is a photoreceptor drum created in this way with improved charging, transfer charger, and developing bias to negative polarity.
When the image was produced by mounting it on a Ricoh copying machine, a clear image was obtained. When the surface potential of the photoreceptor was measured immediately after passing through the charging charger at this time, it was found to be -5oo.
It was v. Thereafter, the photoreceptor was charged and exposed too many times, and the same operation was performed. There was no decrease in image density and the surface density was -730V.

Example 14 The same intermediate layer coating solution as in Example 7 was dip coated on an AQ drum with a wall thickness of 3 nm and 80φ x 340nys at 130°C.
Heat drying was performed for 20 minutes to form an intermediate layer having a film thickness of 1. Furthermore, the same charge generation layer coating solution as in Example 7 was dip coated on top of this, and the coating was dried by heating at 130°C for 20 minutes to obtain a zero
．． An IP charge generation layer was provided. Further, a charge transfer layer coating solution was dip coated on top of this and dried by heating at 130°C for 30 minutes to a film thickness of 20. A charge transport layer was obtained.

FT4060 is a photoreceptor drum created in this way with improved charging, transfer charger, and developing bias to negative polarity.
(-Ricoh Co., Ltd.) to produce an image, a clear image was obtained. At this time, the surface potential of the photoreceptor was measured immediately after passing through the charging charger, and it was found to be -800.
It was V. Thereafter, this photoreceptor was further charged and exposed 10,000 times, and then the same operation was performed. There was no decrease in image density and the surface potential was -750V.

Comparative Example 4 A photoreceptor similar to that of Example 13 was prepared using the same shoe coating solution as that of Comparative Example 1, and the initial surface potential was -800 V, but after 10,000 repetitions. The surface potential after that was significantly lowered to -520V, and a decrease in image density was also observed.

[Brief explanation of drawings]

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

Claims (1)

[Claims] (1) An electrophotographic photoreceptor comprising an intermediate layer and a photosensitive layer sequentially provided on a conductive substrate, wherein the intermediate layer contains an aliphatic alcohol.