JPS6097363A - 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 The present invention relates to an electrophotographic photoreceptor having a conductive intermediate layer between a substrate and a photosensitive layer.

An electrophotographic photoreceptor basically consists of a substrate and a photosensitive layer (1'
# has been completed. However, if the substrate is insulating, such as paper or plastic, a conductive coating must be provided on the substrate to allow the charge to flow. In addition, when the substrate is a metal such as aluminum, copper, brass, stainless steel, etc., it is not necessary to form a conductive film, but it is necessary to improve the coatability of the photosensitive layer, protect the photosensitive layer from electrical damage, and protect the substrate surface. It is effective to form a coating layer to cover defects such as

This coating layer must have sufficiently low electrostatic resistance, so it must be a υ conductive film.

Since the conductive film described above is formed between the substrate and the photosensitive layer, it is usually called an intermediate layer. Conventionally, such an intermediate layer has been made of materials such as lithium chloride, sodium chloride, etc., dissolved in water-soluble resins (such as lithium chloride, sodium chloride, etc.), 15-livinyl alcohol, methyl cellulose, etc., or polymeric quaternary ammonium salts and polymeric quaternary ammonium salts. It is known to use polymer electrolytes such as sulfonates.

However, these resistance increases under slopes with low humidity,
For this reason, it was difficult to use it as a photographic photoreceptor. Further, when an intermediate layer is formed to cover defects on the surface of the substrate, it is necessary to increase the thickness of the intermediate layer, and for this purpose, it is also necessary to lower the resistance of the intermediate layer.

Since it is difficult to obtain an intermediate layer with low resistance using only a single resin, there is a method of using conductive powder dispersed in the resin. As the conductive powder, metal powders such as nickel, copper, silver, and aluminum, metal oxide powders such as iron oxide, tin oxide, antimony oxide, and indium oxide, and carbon powders are used. Since such a conductive paint in which conductive powder is dispersed in a resin is a powder dispersion system, it has the disadvantage that the surface on which the coated film is formed inevitably becomes rough or roughened.

However, since the surface of the intermediate layer greatly contributes to the image quality of the electrophotographic photoreceptor, it is required to have a very clean and smooth surface.

However, as mentioned above, the conventional conductive paint layer has defects in its surface properties, so electrophotographic photoreceptors using this have the problem of not being able to obtain high-quality copy images. .

An object of the present invention is to provide an electrophotographic photoreceptor using an intermediate layer having good planarity.

The present invention is an electrophotographic photoreceptor characterized by having an intermediate layer formed by dispersing conductive powder and binder resin using a surfactant between a substrate and a photosensitive layer. Through numerous experiments, we have found that due to the presence of pigments (conductive powders), coating films of dispersion paints are prone to coating defects such as color unevenness, color separation, orange skin, and pigment floating. The agglomeration caused surface roughness, but these defects caused the pigment to
The present invention was completed based on the fact that this can be prevented by dispersing with an activator.

When a pigment is dispersed using a surfactant, the pigment is dispersed more finely and uniformly due to its movement. Furthermore, during coating, the surface tension of the coated surface is lowered, making it less likely that defects will occur in the coating.

Surfactants include nonionic, cationic, anionic, and amphoteric types, and in the present invention, any surfactant may be used as long as it improves the dispersibility of the pigment. Examples of surfactants include aliphatic polycarboxylic acids, polyaminoamide phosphates, linear alcohol ethoxylates, nonylphenol ethoxylates, octylphenol ethoxylates, polynuclear phenol ethoxylates, higher alcohol sulfates, higher alcohol ether sulfates, aromatic Phosphate ester, aliphatic phosphate ester,
Polyoxyethylene glyfluorate, polyoxyethylene glycol stearate, alkylbenzene sulfonate, trialkylammonium chloride, coconut oil jetanolamide, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide Examples include adducts, perfluoroalkyltrimethylammonium salts, perfluoroalkyl phosphate esters, and various other types are also known. Among these, @ chain alcohol ethoxylate threads, phenol ethoxylate threads, phosphoric acid ester threads, aliphatic carboxylic acid threads, fluorine threads (fluoro compound threads), etc. were particularly suitable.

In addition, 0.0% of the non-volatile content of your conductive paint
01 to 1 weight is suitable. This amount added is 0.001
If the amount is less than 1% by weight, no initial effect will be obtained, and if the amount is more than 1% by weight, it may become difficult to overlay the underlying photosensitive layer or resin layer on the intermediate layer.

As the pigment, it is possible to use conductive powders as described above, as well as non-conductive powders coated with tin oxide and antimony monoxide.

This conductive powder preferably has a particle size of 0.01 to 1μ, and the content in the layer is 10 to 90μ.
Heavy JjLJ, preferably 40 to 80 wt.

The resin for dispersing the conductive powder must (1) have strong adhesion to the substrate, (2) have good dispersibility of the powder, (5) have sufficient solvent resistance, etc. It can be used as long as it satisfies the following conditions, but in particular, curable rubber,
Thermosetting resins such as polyurethane resins, epoxy resins, alkyd resins, polyester resins, silicone resins, acrylic-melamine resins, and phenolic resins are suitable. The volume resistivity of this intermediate layer is suitably 10<16 >[Omega]d or less, preferably 10<12 >[Omega] or less, and the blending ratio is selected so as to achieve such a value. Note that if the resistivity is sufficiently low, it is also possible to add a non-conductive pigment. Examples of these are zinc oxide, titanium oxide,
Examples include calcium carbonate, alumina, barium carbonate and barium sulfate. These are effective in increasing the whiteness of the paint and reducing the cost of the paint. The pigment can be dispersed by conventional methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, and a colloid mill. When the substrate is in the form of a sheet, wire bar foot, blade coat, knife coat, roll coat, and screen coat are suitable for coating, and when the substrate is in the form of a cylinder, the dip coating method is suitable. ing.

The thickness of the coating film varies depending on the surface roughness of the substrate, and a thickness that provides smoothness is selected, but it is preferably at least twice the maximum roughness of the substrate surface. If a photosensitive layer is applied directly onto the intermediate layer, the photosensitive material may penetrate into the fine pores of the intermediate layer, be buried, or become photosensitive due to the interaction between the conductive powder and the photosensitive material. Characteristics may change. Therefore, it is preferable to provide a resin layer (adhesive layer) containing no conductive powder on the intermediate layer. Such resins include, for example, water-soluble resins such as polyvinyl alcohol, polyvinyl methyl ether, polyvinyl pyridine, polyvinyl pyrrolidone, polyethylene oxide, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid, casein, glutinous acid, and starch. , polyamide resin, phenol flll
Resins such as polyvinyl formal, polyurethane elastomer, alkyd resin, ethylene-vinyl acetate copolymer, and vinylpyrrolidone-vinyl acetate copolymer are mentioned. According to the results of experiments conducted by the present inventor, polyamide resin was optimal. Polyamide resins are linear polyamides, typified by so-called nylons and copolymerized nylons. In the present invention, since it is suitable to apply it onto a substrate in a solution state, a low to non-crystalline one is preferable. Such a resin can be obtained by copolymerizing a mixture of two or more types of nylon raw materials. Alternatively, so-called type 8 nylon, which is made by treating the amide group of nylon with formalin and alcohol, is also effective.

The thickness of the polyamide resin layer is approximately 0.3 to 2 μm.

A photosensitive layer is formed on this. The photosensitive layer is formed by coating dye-sensitized zinc oxide, selenium powder, amorphous silicon powder, polyvinyl carbazole, phthalocyanine pigment, oxadiazole pigment, etc. together with a binder resin as required.

Furthermore, when using organic photoconductive materials, an effective method for improving properties is to combine a charge generation layer that generates charge carriers upon exposure to light and a charge transport layer that has the ability to move the generated charge carriers. There is also.

The charge generation layer may include azo pigments such as Sudan Red and Guianpuru; quinone pigments such as Algol Yellow and Pyrenequinone; quinocyanine pigments; Charge-generating substances such as phthalocyanine pigments such as copper phthalocyanine, quinacridone pigments, and pyrylium dyes are combined with binders such as polyester, polystyrene, polyvinyl acetate, acrylic, polyvinyl butyral, polyvinylpyrrolidone, methylcellulose, hydroxypropylmethylcellulose, and cellulose esters. It is formed by being dispersed in resin. Alternatively, it can also be formed by vapor deposition or the like. The thickness of the charge generation layer is approximately 0.05 to 0.2 μm.

The charge transport layer may contain a polycyclic aromatic compound or a window containing indole, carnosol, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, triazole, etc. in the main chain or side chain. It is formed by dissolving a hole-transporting substance such as a compound having a monocyclic compound or a hydrazone compound in a resin that has film-forming properties. This is because the charge transporting substance generally has a low molecular weight and has poor film-forming properties by itself. Such trees include polycarbonate,
Polyarylate, polystyrene, polymethacrylate esters, styrene-methyl methacrylate copolymer, polyester, styrene-acrylonitrile copolymer,
Examples include polysulfone. The thickness of the charge transport layer is 5~
It is about 20μ.

Since the electrophotographic photoreceptor of the present invention has a very smooth conductive layer, the substrate itself does not need to be conductive. Alternatively, since the surface of the substrate may be rough, the cost for processing the substrate can be significantly reduced.

Hereinafter, the present invention will be explained according to examples.

Example 1 8 parts by weight of titanium oxide powder (manufactured by Sakai Chemical Co., Ltd.) and 8 parts of tin oxide powder (manufactured by Mitsubishi Metals Co., Ltd.) were mixed with epoxy resin (product name: Ebicoat 828). , manufactured by Shell Chemical Co., Ltd.) and !:) were dispersed together with 10 parts of luene in a ball mill for 5 hours.

On the other hand, in addition to the same formulation, a surfactant (trade name! 5C5-
105, manufactured by Mudenka ■) and 016 parts were added and dispersed in the same manner.

6 were produced by adding 1 part of triethylenetetramine as a curing agent to each of the obtained dispersions and then drawing.
It was coated on the surface of an aluminum cylinder measuring 0φ×26 Umm and cured by heating at 110° C. for 2 hours. In this way, a 20 μm thick intermediate layer was formed. The surface roughness of the aluminum syringe was 4μ, but the surface roughness of the intermediate layer (A) to which the surfactant was added was 0.5μ, and the surface smoothness was greatly improved. On the other hand, the smoothness was inferior to that of the intermediate layer to which no surfactant was added (the surface roughness of Bl was 22μ).

Next, copolymerized nylon resin (previous product name + 0M8LIUU
, manufactured by Azuma Shishiri) 1 part, type 8 nylon resin (product name +
FIF3QT, Teikoku Kagaku ■li 1 part methanol 10 parts
part, and 8 parts of toluene. This was applied onto the conductive layer, and a 0.5μ thick polyamide resin layer (adhesive layer) was formed.

Next, 5 parts of zinc oxide powder for electrophotography (manufactured by Hakusui Kagaku ■), 0.2 parts of Rose Bengal, and nylon resin (product name: E
F30T) 0.2 parts, methanol 5 parts, n-heptane 5 parts
Add to a solution consisting of 0 parts and mix with a homogenizer for 20 parts.
Dispersed for minutes.

This was taken out by suction filtration and thoroughly dried at 80°C to obtain dye-sensitized zinc oxide.

To 60 parts of this zinc oxide, acrylic resin (trade name AircryPase CMZ-20, manufactured by Fujikura Kasei @, hardness 40%) 12
1 part, and 45 parts of toluene were added and dispersed in a ball mill for 4 hours. Applying the dispersion liquid onto the undercoat layer 22
A μ-thick photosensitive layer was formed and thoroughly dried at 80°C. Next, apply an acrylic resin emulsion (product name: Nearon H) on top of this.
D-11 (manufactured by Toagosei Kagaku ■)) was diluted with water, coated on the photosensitive layer, and dried with hot air at 70°C to form a 4 μm thick protective layer.

This photoreceptor was charged with -5.5 KV, the image was turned off, developed with dry toner, transferred to plain paper, and then a urethane rubber blade with a thickness of 1 printing and a hardness of 70° was placed at an angle of e3° and a pressure of 4fw/I+.
Used in a copying machine where the blade is cleaned by pressing it with +.

When looking at the copied images, the image of the prisoner had very good image quality, whereas in the case of (B), small scratches were seen throughout the image.

Examples 2 to 3 When the surfactant in Example 1 was replaced with a nonylphenol ethoxylate type surfactant (trade name I NF-660, manufactured by Kadenka Co., Ltd.) (Example 2), aliphatic Phosphate ester surfactant (product name! ps-44
The same effect as in Example 1 was also obtained in the case of replacing it with 0Fi (manufactured by 0Fi, non-electrified ■) (Example 3).

Example 4 Titanium oxide powder (10 parts of titanium oxide (mli!), 7 parts of tin oxide powder (manufactured by Mitsubishi Metals), 16 parts of acrylic resin (trade name: Nearcridic A405, manufactured by Dainippon Ink@)
part, melamine resin (trade name: Varnish-Perbeckamine L12)
1, manufactured by Dainippon Ink (■)) and 20 parts of toluene were dispersed in a ball mill over 6 hours. In addition, 03 parts of a perfluoroalkyl ethylene oxide surfactant (trade name: F142I, manufactured by Dainippon Ink ■) was further added to the same blending ratio and dispersed in the same manner.

On the other hand, an aluminum pipe with an outer diameter of 60 mm was cut into 260 mm pieces and used as a substrate. This pipe was manufactured by extrusion molding, and there were some small scratches and protrusions in some parts. The above two types of dispersion liquids were respectively coated on this surface by a dipping method and cured by heating at 170° C. to form an intermediate layer C) or ψ) having a thickness of 20 μm.

However, when the surface was observed, it was found that (C) had a partial protrusion on the base, and the conductive layer was repelled around the protrusion. Also,
Small undulations like lint and yuzu skin were observed on the entire surface of the coating film.

On the other hand, in the case of (D), there was no repellency or burrs, and the surface was very clean. On top of this, the same polyamide resin layer as in Example 1 was formed.

Next, 10 parts of a disazo pigment having the following structural formula, 6 parts of cellulose acetate butyrate resin (trade name + (!AB-381i Eastman Chemistry Department)) and 60 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using 1φ glass beads. 100 parts of methyl ethyl ketone was added to this dispersion, and the mixture was dip coated onto the undercoat layer, followed by heating and drying at 100° C. for 10 minutes to form a charge generating layer with a coating rate of 0.07 r/m 2 .

Next, 10 parts of a hydrazone compound having the following structural formula and a styrene-methyl methacrylate copolymer resin (trade name: M
12 parts of S-200 (manufactured by Nippon Steel Chemical Co., Ltd.) were dissolved in 70 parts of toluene, coated on the charge generation layer, and dried at 100° C. for 60 minutes to form a charge transport layer with a thickness of 16 μm.

When the electrophotographic photoreceptor thus produced was mounted on a copying machine, a copy image (D) of good quality was obtained. On the other hand, in the case of the intermediate layer C), patterns of repelling and waviness were also generated in the copied image.

Example 5 In place of the surfactant in Example 4, an aliphatic polycarboxylic acid surfactant (product name: +2150, Kusumoto Kasei ■!!
'! ), a similar effect was obtained.

Patent applicant: Canon Co., Ltd. Representative: Patent attorney Yu Karino

Claims (2)

[Claims] (1) An electrophotographic photoreceptor characterized by having an intermediate layer formed by dispersing conductive powder in a binder resin using a surfactant between a substrate and a photosensitive layer. (2) The electrophotographic photoreceptor according to claim 1, further comprising a resin layer containing no conductive substance on the intermediate layer.