JPH0279858A - Electrophotographic sensitive body - 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] [Industrial application field] The present invention relates to improvements in electrophotographic photoreceptors.

[Conventional technology]

In recent years, organic photosensitive materials, which have advantages such as low cost, productivity, and non-pollution, have become popular as photoconductors used in electrophotographic copying machines.

Organic electrophotographic photoreceptors include photoconductive resins such as polyvinylcarbazole (PVK) and PVK-TN.
A charge transfer complex type photoreceptor represented by F (2,4,7-dolinitrofluorenone), a pigment dispersion type represented by a phthalocyanine binder, and a functionally separated type photoreceptor using a combination of a charge generation substance and a charge transport substance. etc. are known,
In particular, functionally separated photoreceptors are attracting attention.

When such a functionally separated high-sensitivity photoreceptor is applied to the Carlson process, it has low chargeability and poor charge retention (high dark decay), and these characteristics deteriorate significantly with repeated use, resulting in poor image quality. above.

This may cause density unevenness or decrease in image density, or in the case of reversal development,
It has the disadvantage of causing scumming.

Furthermore, in general, high-sensitivity photoreceptors have reduced chargeability due to pre-exposure fatigue. This pre-exposure fatigue is mainly caused by light absorbed by the charge-generating material, so the longer the charges generated by light absorption remain in the photoconductor in a mobile state, the more the number of charges increases. It is thought that the lower the chargeability becomes, the more the chargeability decreases due to pre-exposure fatigue. In other words, even if a charging operation is performed while the charge generated by light absorption remains, the surface charge will be neutralized by the movement of the remaining carriers, so the surface potential will increase until the residual charge is consumed. Therefore, the rise in surface potential is delayed by the amount of pre-exposure fatigue, and the apparent charge level 4 becomes lower.

To address the above-mentioned drawbacks, JP-A-58-18637 discloses an intermediate layer in which an organic titanium compound is dispersed.
In JP-A-60748 and JP-A-59-46653, an intermediate layer in which an organometallic compound is dispersed is disclosed.
No. 223438 and Japanese Patent Application Laid-open No. 121043/1983 disclose an intermediate layer made of zirconium alkoxide or silane and a pulling agent dispersed therein.
Thermoplastic polycarbonate resins are disclosed in JP-A No. 2552, JP-A-60-142341, and JP-A-60-117561.

An intermediate layer in which acrylate resin, methacrylate resin, etc. are dispersed is disclosed.

[Problem to be solved by the invention]

However, conventionally known electrophotographic photoreceptors are still insufficient in terms of deterioration in chargeability due to repeated use, especially in terms of delay in the rise of the 4th charge, and furthermore, changes in residual potential are large, and further improvements are desired. was.

The present invention is suitable for use in electrophotography, which has high sensitivity, significantly reduces chargeability due to pre-exposure fatigue, has no delay in the rise of charging potential even after repeated charging and exposure, and has small changes in residual potential. The purpose is to provide a photoreceptor.

[Means to solve the problem]

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

An electrophotographic photoreceptor characterized in that an intermediate layer contains a crown ether is provided.

For photoconductors with a protective layer, the abrasion resistance of the photoconductor,
In order to improve ozone resistance and the like, an intermediate layer is required between the photosensitive layer and the protective layer to increase adhesion and to prevent charge injection from the protective layer.

Conventionally, materials for the intermediate layer having such a function include, for example, epoxy resin, polyester resin, polyamide resin, polystyrene resin, polyvinylidene chloride resin, polyvinyl acetate, and polyvinyl chloride.

Various organic polymer compounds such as acrylic resins, silicone resins, and fluororesins; Silane coupling agents such as trimethylmonomethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; Titanium A binder resin formed by one or more combinations of metal alkoxides such as tetrabutoxide, aluminum tripropoxide, and zirconium tetrabutoxide; metal acetylacetone complexes such as titanium acetylacetate and zirconium acetylacetonate is used. It is being

However, when these resin binders are used as intermediate layer forming materials, they may suffer from pre-exposure fatigue or repeated use.
The rise of the charging potential becomes slower.

Further, there was a problem that charging characteristics were also deteriorated.

The present inventors focused on the intermediate layer of an electrophotographic photoreceptor, which is formed by successively laminating a photosensitive layer, an intermediate layer, and a protective layer on a conductive substrate, and as a result of intensive studies to eliminate the above-mentioned drawbacks, the inventors found that By containing crown ether in the intermediate layer,
The present inventors have discovered that an electrophotographic photoreceptor can be obtained that has no delay in the rise of the 4th charge after repeated use and has small changes in residual potential, and has completed the present invention.

In the present invention, as described above, an intermediate layer in which a crown ether is dispersed is provided on the photosensitive layer.6 Examples of the crown ether used in the present invention are as follows.

Preferably, the number of oxygen atoms constituting the ring is 3 to 8,
Examples of such raw ethers include the following compounds.

Benzo 9 Crowns 3 Ether 12 Crowns 4
Ether 18 Crown 6 Ether Dibenzo 18
Crown 6 ether □ Tribenzo 18 crown 6 ether Tetrabenzo 24 crown 8 ether 15 crown 5 ether 21 crown 7 ether Benzo 15 crown 5 ether Core Nialpoly (dibenzo 18 crown 6 ether) The content of the crown ether used in the present invention is intermediate. Preferably from 0.1 to 100 parts by weight of the binder resin of the layer.
The amount is 50 parts by weight, more preferably 0.2 to 20 parts by weight.

If the amount added is less than this, the effect of the present invention cannot be obtained,
Moreover, if the amount added is more than this, the sensitivity will decrease. The thickness of this intermediate layer is usually less than 10 thresholds, preferably less than 1 μm.

The present invention will be explained in more detail below.

The conductive substrate is intended to supply charges of opposite polarity to the charged charges to the substrate side, and has an electrical resistance of 10
It is possible to use a material that has a resistance of aΩcm or less and can withstand the film forming conditions of the intermediate layer, charge generation, and charge transfer layer. Examples of these are AQ, Ni, Cr, Zn
, vacuum evaporation, sputtering, and spray painting on the surfaces of electrically conductive metals and alloys such as styrene-free, inorganic insulating materials such as glass and ceramics, and organic insulating materials such as polyester, polyimide, phenol resin, and nylon resin paper. AQ, Ni, Cr
, Zn, stainless steel, carbon, SnO2, In, O,
Examples include those coated with an electrically conductive material such as

The photosensitive layer in the present invention may be of either a single layer type or a laminated type.

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 oxide, amorphous silicon powder, crystalline selenium powder, phthalocyanine pigment, azo pigment, and binder resin. Further, if necessary, it is formed on the conductive layer together with a charge transfer substance which will 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 μl.

In the case of a laminated type photosensitive layer, the charge transfer layer is a layer that functions to transfer charges generated and separated in the charge generation layer upon exposure to erase charges induced in the conductive layer. In order to achieve the purpose of retaining charged charges, it is required to have high electrical resistance, and in order to achieve the purpose of obtaining a high surface potential from the retained charges, it is necessary to have a low dielectric constant and good charge mobility. required. 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 organic charge transfer substances include poly-N-vinylcarbazole compounds, pyrazoline compounds, α-phenylstilbene compounds, hydrazone compounds, diarylmethane compounds, triphenylamine compounds, divinylbenzene compounds, and Conventionally known compounds such as oleic compounds, anthracene compounds, oxadiazole compounds, and diaminocarbazole compounds can be used.

These organic charge transfer substances other than polymers such as polyvinylcarbazole include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polycarbonate, and polyether, as well as polystyrene, polyacrylate, polymethacrylate, polyN-vinylcarbazole, and polyvinyl. It is used by blending into resins such as polymers and copolymers such as butyral, styrene-butadiene copolymer, and styrene-acrylonitrile copolymer.

Furthermore, a plasticizer is added to these as necessary. Examples of such plasticizers include halogenated paraffins,
Examples include dimethylnaphthalene, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and polymers and copolymers such as polyester. Roll coating method in which the charge transfer substance, the above-mentioned binding resin layer, and silicone oil (as a leveling agent during film formation) are dissolved in an organic solvent.

A film is formed on a conductive substrate by a dip coating method, a spray coating method, a blade coating method, etc., and is dried and cured at 50 to 200°C to a film thickness of 5 to 100. form a charge transport layer.

The ratio of the charge transfer substance to the resin binder is 2/8 to 8/2 by weight, and the amount of silicone oil to the resin binder is 0.
001% to 1% by weight.

The charge generation layer is a layer whose purpose is to generate and separate charges by image exposure. In the present invention, the charge generation layer is a layer in which organic dyes and pigments, crystalline selenium, or arsenic selenide are used as a charge generation substance. Examples of 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.

Face JLIQ -1-Δ--O face"Lnu -11Δ--1 face n
-To Kazuichi---Face] [Correct
-1-Δ---Face"L fire -Each person 111 red ■Length--com Red and long--Com 1 and h -Each person 111 and length -Each person 11 face"L Yang −1−Δ−−−face” 1 positive −11 to 111 face J [gap
-n face” [hi -8= LLI! IQ -6=Face"1
-11 to 11” [Clothes
-1-Δ-11 These organic dyes and pigments can be dispersed in a resin or without a resin by adding an organic solvent and using the same method as above, such as a ball mill, sand mill, triple roll, attritor, or ultrasonic method. and use it. As the resin (binder) for dispersing these organic dyes and pigments, the same resin as that used in the charge transfer layer can be used.

The charge generation layer is formed and dried in the same manner as the charge transfer layer to form a charge generation layer having a thickness of 0.05 to several layers.

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. Examples of such charge-transferable substances include polyvinylcarbazole and its dielectrics (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, and pyrazoline. , hydrazone, diarylmethane, α-phenylstilbene, triphenylamine compounds, and other nitrogen-containing compounds and diarylmethane compounds, but polyvinylcarbazole and its derivatives are particularly preferred, and these substances may also be used in combination. Good too. 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 appropriate content of this type of charge generating substance is 30-90% by weight of the entire layer. Further, when a charge generating substance is used, the thickness of the charge generating layer is preferably 0.2 to 5 -.

Examples of the resin used in the protective layer of the present invention include polyester resin, polycarbonate resin, polystyrene resin, polyvinyl butyral resin, polyamide resin, polyurethane resin, fluororesin, cellulose resin, vinyl chloride resin, acrylic resin, polypropylene resin, epoxy resin,
Examples include silicone resin, alkyd resin, and melamine resin. The protective layer is formed and dried in the same manner as the photosensitive layer, and preferably has a thickness of 1 to 30 μl. Preferably, the protective layer contains a metal oxide for preventing an increase in residual potential. in particular.

SnO,, sb, o,, In, O,, TiO2, etc., and the content is in the range of 10 to 80% by weight with respect to the protective layer.6 The particle size is 0.5. It is preferably 0.3ρ or less.

〔Example〕

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

Example 1 [Coating liquid for charge transfer layer] Shinn3 Tetrahydrofuran 80 [Coating liquid for charge generation layer] The azo pigment Nal and cyclohexanone were mixed in a weight ratio of 1:1.
6 was placed in a ball mill pot, and ball milling was performed for 48 hours using a stainless steel pole.

After adding an equal amount of cyclohexanone and milling for 24 hours, the solution taken out was diluted with cyclohexanone while stirring to give a solid content concentration of 1% by weight, which was used as a coating solution for charge generation.

[Coating liquid for intermediate layer]

Dicyclohexano 18 crowns 6 0.01 parts by weight Ether zirconium acetylacetone 1 part by weight γ-methacryloxypropyltri 1 part by weight Methoxysilane n-butanol 40 parts by weight [
Coating liquid for protective layer] Polyester resin 10 parts by weight (v-zoo manufactured by Toyobo Co., Ltd.) Dichloroethane 90 parts by weight These were placed in a ball mill pot and ball milled for 48 hours to obtain a coating liquid for protective layer.

Next, apply the charge transfer layer coating liquid onto the i-plate at a rate of 6 mm/s.
It was coated by dip coating at a pulling speed of ee and dried by heating at 120° C. for 30 minutes to form a charge transfer layer with a thickness of 20 layers. Further, on top of that, the coating liquid for the charge generation layer is pulled up at a rate of 5 mm/see.
A charge generation layer was provided by dipping and drying for 120'Cl2O minutes.The intermediate layer coating solution was applied thereon by dip coating at a pulling speed of 9I1 m/see, and then heating and drying for 80'Cl2O. We created a middle class of 2,000 people.Furthermore,
On top of that, the coating solution for the protective layer was spray-coated for 130 minutes.
A protective layer having a film thickness of 5 ps was provided by heating and curing at ℃ for 30 minutes to produce a photoreceptor.

Comparative Example 1 Dicyclohexano 18 crown 6 from the intermediate layer of Example 1
A photoreceptor was produced in the same manner as in Example 1 except that the ether was removed.

Example 2 Pigment Na was used instead of pigment Nα1 in the charge generation layer of Example 1.
A photoreceptor was produced in the same manner as in Example 1 except that No. 47 was used.

Comparative Example 2 A photoreceptor was produced in the same manner as in Example 2, except that dicyclohekilyl-18-chlorine-6 ether was removed from the intermediate layer.

Example 3 Dicyclohexano 18 crown 6 in the intermediate layer of Example 1
A photoreceptor was prepared in the same manner as in Example 1 except that poly-dibenzo 18 crown ether was used instead of ether.

Example 4 A photoreceptor was produced in the same manner as in Example 1, except that the protective layer coating liquid in Example 1 was replaced with the following.

[Coating liquid for protective layer] Phenoxy resin (Union Carbide Cor
p PKHJ)/cyclohexanone 20% solution 25
A liquid consisting of parts by weight of tin oxide powder, 5 parts by weight, and 70 parts by weight of cyclohexanone was dispersed in a ball mill for 72 hours, and diluted with cyclohexanone to give a solid concentration of 10 parts by weight.

Comparative Example 3 A photoreceptor was produced in the same manner as in Example 4 except that dicyclohexano 18 crown 6 ether was removed from the intermediate layer of Example 4.

Example 5 A photoreceptor was produced in the same manner as in Example 4, except that the intermediate layer coating liquid in Example 4 was replaced with the following.

[Intermediate layer coating liquid]

Nylon resin (manufactured by Toshi, CM8000) 2 parts by weight Methanol 60 parts by weight Butanol 38 parts by weight Comparative Example 4 The same procedure as in Example 5 was performed except that dicyclohexano 18 crown 6 ether was removed from the intermediate layer of Example 5. A photoreceptor was produced.

The electrophotographic properties of the electrophotographic photoreceptor produced as described above were evaluated in the following manner using an electrostatic copying paper tester (Model 5P428 manufactured by Kawaguchi Denki Seisakusho).

First, it was corona charged at +6KV for 20 seconds and then left in a dark place until the surface potential reached +800V.

4, 5 Lux of tungsten light was irradiated to determine the surface potential v2.2 seconds after the start of charging at this time. The required exposure amount is 5 (Lux 5ee) so that the surface potential becomes +400V during light irradiation.
) was measured. Also, after this, the color temperature of 2856 is applied to the photoreceptor.
A tungsten light of 100,000 Luxsee was irradiated at 100°C, and the charged potential v2' and the exposure amount S' were determined in the same manner as above. The results are shown in Table 1.

Table 1 The fabricated photoreceptor was 3mm thick, 80φX 340mm.
It was attached to a mm AQ drum and mounted on an FT4060 (a copying machine manufactured by Ricoh) to produce an image, and the image production was repeated 10,000 times. The results are shown in Table 2.

Table 2 [Effects] The electrophotographic photoreceptor of the present invention has the above-mentioned structure and uses a crown ether dispersed therein as the intermediate layer, so that it has high sensitivity and does not reduce chargeability due to pre-exposure fatigue. It is extremely small, and has the remarkable effect that the charging characteristics do not deteriorate even after repeated charging and exposure, and the increase in residual potential is small.

Claims (1)

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