JPH0727265B2 - Multilayer photoconductor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate type photoconductor in which at least a charge generation layer and a charge transport layer are provided on a substrate.

2. Description of the Related Art Conventionally, selenium, zinc oxide, titanium oxide, selenium, as a photosensitive material for forming a photosensitive layer of a photoreceptor used in electrophotography,
Inorganic photoconductive materials such as cadmium sulfide have been used. However, these have a number of drawbacks, and in general, many of them are highly toxic, and there are also problems with moisture resistance and the like.

On the other hand, the photoreceptor using the organic photoconductive material has
Although it is excellent in terms of lightness and price, it still has problems in terms of sufficient sensitivity, durability and stability due to environmental changes.

In recent years, a multi-layer type photoconductor in which the functions of charge generation and transport are separated has been proposed, and the drawbacks of conventional photoconductors using organic photoconductive materials have been greatly improved, resulting in the practical use of organic photoconductors. , Is making rapid progress.

The laminated photoreceptor has a structure in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate such as metal aluminum or copper.

These laminated type photoreceptors have charge retention, high sensitivity, repeated stability, dielectric breakdown resistance, abrasion resistance, durability, moisture resistance,
It is required to satisfy the basic conditions such as transferability, cleaning property and storage stability.

Further, the laminated type photoconductor is also used for a laser printer, and high image reliability and repetitive stability at the time of reversal development are required.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional laminated type photoreceptor, particularly in the case where the charge generation layer is a dispersion film in which a pigment is dispersed in a resin, adhesiveness with a substrate, coating property, charge transport layer from the substrate There were various problems such as charge injection into the. These have a serious problem of the conductive substrate, and it is necessary to improve defects on the substrate, charge injection property and adhesive property.
As measures against these problems, JP-A-58-30757 and JP-A-58-957 have been adopted.
No. 44 proposes a photoreceptor using an undercoat layer. JP-A-58-14841, JP-A-59-41360, JP-A-61
No. 140947 proposes a photoconductor in which an aluminum support is anodized.

However, the electric resistance of the undercoat layer disclosed in JP-A-58-30757 and JP-A-58-95744 is greatly affected by changes in the external environment, particularly humidity in the atmosphere.
Fog may occur at low humidity. Further, when the electric resistance is high, a charging potential is applied to the undercoat layer, causing fog in the image as a so-called residual potential. The undercoating layer is required to have such various characteristics, but it is difficult to obtain a good one when only a single resin is used. Therefore, the film thickness of the resin film is made extremely thin, or conductive powder (metal powder or the like) is dispersed in the resin as needed. However, reducing the film thickness of the resin layer has a drawback that the performance as an undercoat layer is not sufficient, while in the undercoat layer in which the metal powder is dispersed, the metal particles are coarse, There is a drawback that the surface property of the pulling layer is lowered.

In particular, even if the conventional laminated type photoreceptor is applied to a laser printer, it is not so effective for the minute black spots generated on the white paper portion during the reversal development.

On the other hand, JP-A-58-14841 discloses that an aluminum support is
Disclosed is a photoreceptor including a step of immersing in water having a specific resistance of 10 ⁶ Ω · cm or more and a temperature of 60 ° C. or more. JP 59-
No. 41360 uses a phthalocyanine vapor deposition film as a charge generation layer,
Disclosed is a photoreceptor in which an aluminum support is treated to form a non-sealing anodized film of at least 4 μm. JP-A-61-140947 discloses a photoconductor in which a barrier layer and a porous layer are provided by previously subjecting the aluminum support to an alumite treatment when forming a-Si on the surface of the aluminum support. . However, in the technologies disclosed in these documents, when the charge generation layer is a dispersion film, no improvement is shown for black spots generated during reversal development, and no description is made conditionally.

An object of the present invention is to provide a photoconductor in which the above drawbacks are eliminated, and specifically to provide a photoconductor having excellent electrophotographic properties by using a specific conductive substrate. .

Means for Solving the Problems The present invention provides a photoreceptor having at least a charge generation layer and a charge transport layer on an aluminum substrate, wherein the charge generation layer is a resin dispersion film of an organic pigment, and the aluminum substrate is
It is characterized by having an alumite layer which has been alumite treated and then subjected to a pore-sealing treatment by the nickel acetate method.

The alumite layer is required to have functions such as imparting adhesiveness, charge injection preventing property, and rectifying property, and in order to satisfy the functions, it is effective to seal the alumite layer by a nickel acetate method. If the sealing treatment is performed by another method, for example, the steam method, the rectifying property is lost and the residual potential increases.

The photoreceptor of the present invention has an aluminum support which is processed into a suitable shape such as a cylinder as a support for the photoreceptor, and is subjected to electrolytic treatment with sulfuric acid or oxalic acid as an electrolytic solution. Form an alumite layer. afterwards,
The sealing treatment is performed by treating with an aqueous solution of nickel acetate. The concentration of nickel acetate is preferably 1 to 15 wt%, preferably 5 to 10 wt%, and the temperature of the aqueous solution is preferably 50 to 80 ° C.

More preferably, the sealing treatment is partially performed. The alumite layer is generally composed of two layers, a barrier layer and a porous layer. Partially means that only the surface of the porous layer is sealed with the voids remaining in the porous layer. The sealing degree can be adjusted by the sealing treatment time, the concentration of nickel acetate, the temperature of the solution, and the like. Impurities such as Ni that entered the alumite layer by the partial sealing treatment allow electrons to flow smoothly, while the barrier property of the alumite layer prevents the injection of holes themselves, resulting in good rectification. can get.

As the obtained alumite layer, especially, the barrier layer has a thickness of 100 to 1000Å and the porous layer has a thickness of 1 to 15 μm.
Things are good. In addition, the sealing treatment gives the alumite layer a more stable film.

When the photoreceptor of the present invention is composed of the above-mentioned substrate having the alumite layer, it becomes a good one in which the generation of black spots, which is a problem particularly in a laser printer for reversal development, is suppressed.

Examples of the organic pigment used in the charge generation layer of the present invention include various azo pigments, perylene pigments, phthalocyanine pigments,
Examples thereof include polycyclic quinone pigments, indico pigments, and quinacridone pigments.

The charge generation layer is prepared by dissolving a binder resin using a suitable solvent and adding the above pigment to the binder resin in an amount of 10 parts by weight based on 100 parts by weight of the binder resin.
~ 200 parts by weight, and 0.1 ~ 1μ of the solution dispersed by ball mill, vibration mill, sand mill, roll mill, etc.
It is obtained by applying to m.

The charge transport layer includes pyrazoline, triphenylmethane, oxadiazole, carbazole, hydrazone, styryl,
Dissolving electron-donating substances consisting of derivatives such as imidazole and substances with charge-transporting properties such as electron-accepting substances such as trinitrofluorenone, tetranitroxanthone, tetracyanoethylene, tetracyanoquinodimethane in film-forming resins It can be obtained by coating and coating to 5 to 30 μm.

Examples of the binder resin used in the charge generation layer and the charge transport layer include polyester, polycarbonate, polymethacrylic acid ester, polyvinyl butyral, silicone resin, epoxy resin, melamine resin, urethane resin, polystyrene and the like.

The photoreceptor of the present invention may have a structure in which a charge generation layer and then a charge transport layer are laminated on an alumite-treated aluminum substrate, or a structure in which a charge transport layer and then a charge generation layer are laminated. Further, those photoreceptors may have a surface protective layer, an undercoat layer or an intermediate layer, if necessary.

Hereinafter, the present invention will be described with reference to examples. In the examples, all "parts" are "parts by weight" unless otherwise specified.

Example 1 As a conductive substrate, aluminum subjected to surface treatment by lathing was used, and an alumite layer was formed on the surface of the conductive substrate by an electrolytic bath containing sulfuric acid 15 vol% at a liquid temperature of 20 ° C. ± 1 ° C. . The barrier layer of the alumite layer was 200Å, and the porous layer was 7 μm. After that, the pores were sealed by treating them in a nickel acetate aqueous solution (concentration: 7 wt%) at a temperature of 50 ° C.

Next, 1 part of titanyl phthalocyanine and 1 part of polystyrene and 50 parts of cyclohexanone were placed in a ball mill pot as a charge generation layer on this substrate and dispersed for 24 hours to obtain a photosensitive coating liquid. By applying and drying this, the thickness
A 0.3 μm charge generation layer was obtained.

Then, on this charge generation layer And 10 parts of polycarbonate resin in 100 parts of tetrahydrofuran were applied so that the film thickness after drying would be 15 μm to form a charge transport layer, and a photoconductor was prepared.

Examples 2 to 4 The sealing treatment with nickel acetate was performed in the same manner as in Example 1 except that the thickness of the barrier layer and the porous layer of the alumite layer was set as follows, and the charge generation layer and the charge transport layer were formed thereon. To form a photoconductor.

Comparative Example 1 A photoconductor was prepared in exactly the same manner as in Example 1 except that the barrier layer of the alumite layer was 50Å and the porous layer was 3 μm, and that the sealing treatment was not performed.

Comparative Example 2 A photoconductor was prepared in exactly the same manner as in Example 1 except that the barrier layer of the alumite layer was 1500Å and the porous layer was 6 μm, and the sealing treatment was performed by steam treatment.

Comparative Example 3 A photoconductor was prepared in exactly the same manner as in Example 1 except that the alumite layer was not provided.

The obtained photoreceptor was corona charged using a powder image transfer type copying machine (EP-470Z manufactured by Minolta Camera Co., Ltd.), and the initial surface potential (V ₀ ) was set to −750 V, the initial potential was 1 / The exposure amount required to reach 2 was E1 / 2 (lux · sec), and the decay rate DDR ₅ (%) of the initial potential and the residual potential Vr (V) when left in the dark for 5 seconds were measured. Further, black spots on a white paper portion on an image when reversal development was performed with V ₀ = −750V and developing bias Vb = −500V were measured. White spots were measured on the solid black portion on the image. The results are shown in Table-1. In Table 1, ◯ means good, and x means problem.

EFFECTS OF THE INVENTION According to the laminated type photoreceptor of the present invention, the adhesiveness between the charge generation layer and the aluminum support is dramatically improved, and
Due to the rectification function of the alumite layer, the charge injection prevention property is improved, black spots which are a problem on the white paper part are suppressed at the time of reversal development, and the coatability of the pigment dispersion coating liquid of the charge generation layer is improved. Excellent electrophotographic characteristics can be obtained.

Continuation of the front page (56) References JP-A-54-89637 (JP, A) Actual development: S59-41360 (JP, U)

Claims (1)

[Claims] 1. A photoreceptor having at least a charge generation layer and a charge transport layer on an aluminum substrate, wherein the charge generation layer is a resin dispersion film of an organic pigment, the aluminum substrate is anodized, and then nickel acetate method is used. A laminated type photoreceptor having an alumite layer which has been subjected to a pore-sealing treatment by.