JPS5924853A - Electrophotographic receptor - Google Patents

Abstract

PURPOSE:To increase adhesion between a substrate and a photosensitive layer, to prevent unfavorable influence of the substrate on said layer, and to enhance electrophotographic characteristics, by forming a resin layer contg. a carbon powder as an undercoat layer on the conductive substrate, and providing a laminate photosensitive layer using another resin on this undercoat layer. CONSTITUTION:The undercoat layer obtd. by dispersing the carbon powder into a thermosetting resin, such as polyurethane or polyamide resin, is formed on a conductive substrate. On this layer a charge generating layer is formed. It is obtained by dispersing a charge generating agent into a soln. of a polyamide, phenolic resin, or an ethylene-vinyl acetate copolymer, and on this layer a charge transfer layer is formed contg. a charge transfer agent and a binder, such as polystyrene or polyvinylpyrrolidone. The resin of the undercoat layer is made different from that of the photosensitive layer, and the solvents used for these layers are made also different from each other in order to avoid dissolution, swelling, etc. of the under layer during forming the upper layer, and also to prevent deterioration of the characteristics of the photosensitive layer due to ruggedness or reflected light, and further to raise adhesion strength between the substrate and the photosensitive layer.

Description

[Detailed description of the invention] The present invention relates to an electrophotographic photoreceptor having an undercoat layer.

? Niko photographic photoreceptors basically consist of a substrate and a photosensitive layer. However, improvements in adhesion between the substrate and the photosensitive layer, coating properties of the photosensitive layer, protection of the substrate, damage from defects on the substrate, protection against electrical breakdown of the photosensitive layer, and protection from electric charge from the substrate to the photosensitive layer. In order to improve injection properties, it is effective to provide an undercoat layer between the substrate and the photosensitive layer.

Conventionally, the undercoat layer is made of, for example, %l:! i] Showa 56-2
sJ! ', IJ vinyl methyl ether, IP +7 vinyl ethyl ether, polyvinylhyridine, polyvinylpyrrolidone, polyethylene oxide, polyacrylic acids, methylcellulose, ethylcellulose, polyglutamic acid, tunosein, gelatin,
Water-soluble (F11 fat was used) such as starch.Water-soluble (F11 fat) has advantages such as being cheap, not causing pollution from solvents, and being able to obtain reasonable photographic properties. Since it is an aqueous solution, it will repel when applied to the substrate.
There were problems such as coating defects such as dripping, pinholes, and unevenness, and a partial decrease in adhesion to the substrate. Therefore, it is also desired to form an undercoat layer using a resin soluble in an organic solvent.

However, when an organic solvent-soluble resin is used as an undercoat layer and a photosensitive layer is applied thereon, the undercoat layer often dissolves due to the solvent. In addition, if the sublayer is formed with a thermosetting resin that does not elute, thermosetting resins generally have high electrical resistance, so if electrophotographic characteristics are taken, a large amount of residual 11 will accumulate. There were drawbacks.

For this reason, it has been thought of dispersing carbon powder in the resin of the undercoat layer to impart conductivity, but since this carbon powder has the property of injecting free carriers, it generates charge especially in the photosensitive layer. When used in an electrophotographic photoreceptor that has a structure in which layers and charge transport layers are separated, dark decay increases.
[Image formation may become impossible.]

When the substrate is made of metal, it tends to reflect light, so depending on the process using the electrophotographic photoreceptor, light may interfere with the incident light for image exposure and the reflected light from the substrate. This may result in complex patterns. In such a case, it is sufficient to eliminate the reflected light from the substrate, but for this purpose as well, it is effective to use an undercoat layer in which black carbon powder is dispersed. However, conventionally, it has not been possible to use an undercoat layer in which carbon powder is dispersed due to the drawbacks mentioned above.

In view of the above drawbacks, the main object of the present invention is to effectively use an undercoat layer in which carbon powder is dispersed. Another purpose is to eliminate defects on the substrate by applying a thick undercoat layer. The aim is to increase the ability to reverse defects and reduce the number of defective products due to defects.

The present invention is characterized in that another resin layer is formed on the undercoat layer in which carbon powder is dispersed, in order to prevent the carrier injection properties of carbon powder from affecting the photosensitive layer. Since the separate resin layer increases the carrier injection property of the carbon powder to 1 (Ii, d2), dark decay of the photosensitive layer can be eliminated.

The conditions required for such a resin layer are: (1) It must be able to sufficiently stop the carrier injectability of carbon powder.
2) Close contact 4' to the undercoat layer in which carbon powder is dispersed
γ(
Examples include low air resistance. As such a resin, a suitable one may be selected from the water-soluble resins mentioned above, and in addition, polyamide resin, phenol resin, polyvinyl formal, polyurethane elastomer, alkyd resin, ethylene-vinyl acetate copolymer, vinyl Resins such as pyrrolidone-vinyl acetate copolymer may also be used. According to the results of experiments conducted by the present inventors, it was found that polyamide resin or phenol resin is optimal.

In other words, the resin for dispersing the carbon powder must (1) have strong adhesion to the substrate, (2) have good dispersibility of the carbon powder, and (3) have sufficient solvent resistance. For this purpose, thermosetting resins such as polyurethane resins, epoxy resins, alkyd resins, l'lyester resins, silicone resins, and acrylic-melamine resins are suitable.

The resin in which carbon powder is dispersed has an electrical resistivity of 1016Q-an or less, preferably 1012Q, n
The following is suitable, and it is suitable that the content of the carbon powder is 5 weight units or more, preferably 15 weight units or more and 60 weight units or less.

Carbon black, graphite, etc. can be used as the carbon powder, and the particle size is about 0.0
5μ to 2.5μ is appropriate. For dispersion, a ball mill,
Conventional methods such as roll milling and sand milling are used.

To explain the present invention in more detail, the substrate is formed by molding a metal such as aluminum, i+' (copper, stainless steel, ωj iron, etc.) into a cylindrical shape, or by forming it into a foil. According to the present invention, since the undercoat layer can be made thicker, it is possible to use a material that is more similar to the surface than the tube surface, and the cost can be reduced accordingly.

A coating of 1-gold in which carbon powder is dispersed is applied onto the substrate and cured by heating. The film thickness may be any thickness as long as it does not accumulate charge. The rougher the substrate surface, the thicker the coating needs to be. Usually it is about 2 to 20μ.

The polyamide resin coated thereon is linear polyamide, and is typified by so-called nylon and copolymerized nylon. In the present invention, since it is suitable to apply the solution onto the substrate, a low to non-crystalline one is preferable. The darning resin can be obtained by copolymerizing a mixture of two or more types of nylon raw materials.

Raw materials for nylon include, for example, caprolactam or 6-aminocaproic acid, which is the raw material for nylon B, hexamethylene diamine, which is the raw material for nylon 66 and nylon 61o, and dicarboxylic acids such as adipic acid and sepacic acid.
11-aminoundecanoic acid, a raw material for nylon 11,
ω-laurolactam or 1, which is the raw material for nylon 12
Examples include 2-aminododecanoic acid.

Although the composition of the polyamide resin influences crystal blindness, solubility in solvents, and the 11-gearability of the coating, such properties are not the object of the present invention.

Polyamide resin is dissolved in alcohol such as methanol or ethanol, but for solution stability, toluene,
Aromatic hydrocarbons such as xylene may also be added. The coating thickness is preferably about 1.3 to 2 μm.

Furthermore, the phenol resin used in place of the polyamide resin is preferably a resol-type alcohol-soluble phenol resin that is produced by reacting carbolic acid and polymerine with an alkali catalyst. An organic acid such as benzenesulfonic acid, toluenesulfonic acid, phenolsulfonic acid, naphthalenesulfonic acid or the like is added in an amount of 10 to 20% by weight as a curing agent to such an alcohol-soluble phenol resin, and the resin is coated. The coating thickness is 1 to 10 μm, and the coating is cured by heating at about 80 to 150°C.

The photosensitive layer coated on the undercoat layer is made by coating dye-sensitized photoconductive substances such as zinc oxide, cadmium sulfide, polyvinyl carbazole, phthalocyanine pigments, and azo pigments together with binders as necessary. Formed by coating. Particularly, when using an organic photoconductive substance, the present invention uses a photosensitive layer consisting of a combination of a charge generation layer that generates a charge phase upon exposure to light, and a charge transport layer that has the ability to transport the generated charge carriers. ,It is valid.

i
, azo pigments such as Jenas Green B, quinone pigments such as Algol Yellow, Pyrenequinone, Indanthrene Brilliant Violet RRP, quinocyanine pigments,
Indigo pigments such as perylene pigments, indigo, and thioindigo, bisbenzimidazole pigments such as India Fast Orange toner, phthalocyanine pigments such as copper phthalocyanine, and charge-generating substances such as quinacridine pigments, polyester, polystyrene, polyvinyl butyral, polyvinyl pyrrolidone, and methylcellulose. , polyacrylic esters, cellulose esters, and other binder resins. Its thickness is about 0.01-1μ, preferably about 0.05-0.5μ.

゛The charge transport layer may contain polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, coronene, etc., or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, etc. in the main chain or side chain. Compounds with nitrogen-containing cyclic compounds such as triazole, hole-transporting substances such as hydrazone compounds, etc.
It is formed by dissolving it in 1 fat. This is because charge transporting substances are generally low molecular weight. This is because it has poor film-forming properties by itself. Such resins include polycarbonate, polymethacrylic acid esters, polyarylate, polystyrene, polyester, folyzalfone, and styrene.
, -acrylonitrile copolymer, methyl methacrylate copolymer, and the like.

1 (X: The thickness of the cargo transport layer is 5 to 20 μm.

According to the present invention, since a paint in which carbon powder is dispersed can be effectively used in the undercoat layer, it is possible to apply a thick undercoat layer, and the number of finishing steps for the substrate surface can be reduced, resulting in cost reduction. When I measured it, I was able to measure it. Next, since the undercoat layer was black, it was possible to eliminate reflected light from the substrate, thereby eliminating light interference. Therefore, the photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser printers, CRT printers, and electrophotographic plate making systems.

Example 1 As part of the carbon powder dispersion department, we developed a paint (trade name Nido-Thai 1-XC-46) in which carbon powder was dispersed in alkyd resin.
, manufactured by Fujikura Kasei) was used. The surface of an 80φ×300mm aluminum cylinder was polished to a smoothness of 2S. Immerse yourself in this surface! The film thickness of carbon dispersed paint is 15
It was coated so as to have a thickness of .mu. and was cured by heating at 150.degree. C. for 30 minutes to form an undercoat layer.

Next, copolymerized nylon resin (product name: Amilan CM 8
000, made by Toshi) (parts by weight, the same applies hereinafter) was dissolved in a mixed solution of 60 parts of methanol and 40 parts of butanol, and coated on the undercoat layer by dipping to form a 1 μ thick polyamide resin layer. I made a profit.

Next, 10 parts of a disazo pigment having the following structural formula, 6 parts of cellulose acetate butyrate resin (trade name: CAD-381; manufactured by East Seven Chemical Co., Ltd.), and 6 parts of cyclohexanone were mixed in a sand mill using 1φ glass beads. / for 20 hours. 100 parts of methyl ethyl ketone was added to this dispersion, and the mixture was applied by dip coating onto the undercoat layer described above, and dried by heating at 100°C for 10 minutes to obtain a coated area of 0.1 y/m2. 1ili
, created a load-producing layer.

Next, 10 parts of a hydrazone compound having the following structural formula and polystyrene resin (trade name: Dialex HF) were added.
-55: Mitsubishi Monsanto Chemical Co., Ltd.) 10 parts was dissolved in 70 parts of monochlorobenzene. This was applied onto the charge generation layer and dried with hot air at 100° C. for 1 hour to form a charge transport layer with a thickness of 12 μm.

Adhesion was examined from above the charge transport layer using the Chromeno-Fuchi method, and the result was 100/100, with no peeling.

#, II separation test, electrophotographic photoreceptor without all tests, -5,
6KV corona QRY TLT, image exposure, dry toner development, toner transfer to plain paper, urethane rubber blade (
The electrophotographic properties were evaluated by attaching it to an electrophotographic copying machine having a cleaning process with a hardness of 70°, a pressure of 109w7cm, and an angle of 200° with respect to the photoreceptor. 'rla was charged to -620V, and a good image could be obtained.

For comparison, a photoreceptor was manufactured in which an iK contact, a charge generation layer, and a charge transport layer were formed on a carbon powder dispersed resin layer without applying a polyamide resin layer. In this case, the charging potential was about -100 V, and no image could be obtained. This is because carbon powder has the effect of injecting holes among free carriers.・In addition, in the case of a photoreceptor in which a polyamide resin layer was applied without applying a carbon powder dispersed resin layer, and a charge generation layer and a charge transport layer were formed thereon, the potential was -620V, which was normal. , fine sushi was partially visible in the image. This was because the surface smoothness of the substrate was 28, so there were some scratches, and the polyamide undercoat layer could not sufficiently cover the scratches. In order to obtain a high-quality image with this layered structure, it is necessary to polish the surface smoothness to 1S or less and use a goo substrate, which increases the cost.

Furthermore, in Example 1, the resin of the carbon powder dispersion coating was a thermosetting alkyl l-' resin, but this was replaced with a coating using a plasticized acrylic resin (trade name Nido-Tite XC-12, Fujikura Kasei), this resin layer swelled when a photosensitive layer was applied on top.
Adhesion to the substrate was O/100.

Example 2 A paint in which carbon black was dispersed in an epoxy resin (trade name: Neo Chaclone Black, manufactured by Musashi Paint Co., Ltd.) was dip-coated to a thickness of 10 μm on a 136φ×300 mm aluminum cylinder, and was cured by heating at 150° C. for 30 minutes. On top of this, the same polyamide resin layer as in Example 1 was formed.

β-type copper phthalocyanine pigment (manufactured by Toyo Ink ■) was purified by successive filtration with water, ethanol, and methyl ethyl ketone. 10 parts of this pigment, 5 parts by weight of hydroxypropyl methyl cellulose resin (trade name: Metrose 608H50, manufactured by Shin-Etsu Chemical), 50'7 parts of water and 5 parts of methanol.
0 parts of a solvent and mixed. Next, the mixture was dispersed for 1 hour using a sand mill device using glass beads. Further, 20 parts of ethanol was added to this dispersion, and the mixture was dip coated onto the polyamide layer to form a charge generation layer having a thickness of 0.1 μm.

The same charge transport layer as in Example 1 was formed on the 11-part charge generation layer to prepare a photoreceptor.

This photoreceptor was attached to a commercially available laser beam printer (trade name: LBP-10, manufactured by Canon) after being modified to be charged (■), and when the printed image was viewed, the image quality was good.

On the other hand, when a photoreceptor was used without forming a carbon dispersion layer, the reflected light from the At surface interfered with the laser beam, resulting in a complicated striped pattern in the printed image. In this case, a black undercoat layer was absolutely necessary.

Actual hfq examples 3 to 4 In place of the polyamide resin coated on the carbon-dispersed tlrjl fat layer in actual Mti examples 1 to 2, 100 parts of phenol resin (trade name: Nibryofen 5010, manufactured by Dog F1 Ink), A solution consisting of 7 parts of paratoluenesulfonic acid and 70 parts of ethanol was applied by dip coating onto the carbon-dispersed resin layer and heated at 100° C. for 10 minutes to form a phenol resin layer with a thickness of 6 μm. When a photosensitive layer similar to that in Examples 1 and 2 was formed on this, the result was still similar! A photoreceptor of 1 ga. was obtained.

In the case of phenol resin, when it was coated directly onto aluminum without forming a carbon-dispersed resin layer, the adhesion was insufficient and was IO/100.

Examples 5 to 6 Paint in which carbon powder is dispersed in polyester resin (trade name Nido-Tite FC404, manufactured by Fujikura Kasei) or paint in which carbon powder is dispersed in silicone resin (trade name Nido-Tite RA6)
5, manufactured by the same company), a similar photoreceptor was also obtained.

Patent applicant: Canon Co., Ltd. Dai Misaki Patent Attorney Kari No Yu

Claims (1)

[Claims] (1) Electrophotography with an undercoat layer and a photosensitive layer on the substrate! (In the photoreceptor, underarm) 1" 4 contains carbon powder and consists of two layers: fc, a resin layer, and another resin layer formed thereon. ，
Feeling C body.