JPH01123247A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body which is excellent overall in electrophotographic characteristics by using an under coating layer contg. silicon carbide for the photosensitive body formed by providing the under coating layer between a conductive base and photoconductive layer. CONSTITUTION:The silicon carbide is incorporated into the under coating layer formed between the conductive base and the photoconductive layer. Since the silicon carbide has an electrical conductivity, the volume resistivity of the under coating layer lowers if the silicon carbide is incorporated into such under coating layer. The surface of the conductive base is thus sufficiently protected by increasing the film thickness of the under coating layer without increasing the residual potential; in addition, the surface of the conductive base can be finished smooth by coating the defects on said surface. Fine powder of a betacrystal type having the good electrical conductivity is preferably used as the silicon carbide layer to be incorporated into the under under coating layer. The fine powder of preferably 0.01-0.5mum is used on order to smoothly form the under coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a photoreceptor having an undercoat layer and a photoconductive layer on a conductive support.

[Prior art and its problems] Photoreceptors used in electrophotographic devices, etc. are those in which a photoconductive layer is formed on a conductive support, or in which this photoconductive layer is combined with a charge generation layer and a charge transport layer. It is widely known to have functionally separated layers and laminate them on a conductive support.

In such a photoreceptor, improvements in adhesion between the conductive support and the photoconductive layer, improvement in coatability of the photoconductive layer, protection of the conductive support, and covering of defects on the conductive support are required. , protection against electrical breakdown of the photoconductive layer, suppression of charge injection from the conductive support to the photoconductive layer, etc. are required.

For this reason, it has been conventionally practiced to provide an undercoat layer between the conductive support and the photoconductive layer.
No. 57 and Japanese Unexamined Patent Publication No. 58-95744 disclose forming an undercoat layer using a polyimide resin on a photoreceptor.

Here, such an undercoat layer is required to have various properties when used in an electrophotographic photoreceptor, and first of all, as an electrical property, electrical resistance is required so as not to affect the electrophotographic properties. is required to be low. That is, if the electrical resistance of the undercoat layer is high, a charged potential remains in the undercoat layer even after discharge, and the so-called residual potential becomes high, causing fog in the image. Therefore, if the undercoat layer is composed only of a resin having high electrical resistance, the residual potential will increase and the image will be blurred.

It is also necessary that the electrical resistance of the undercoat layer is not affected by changes in the external environment, particularly changes in atmospheric humidity. For example, when the electrical resistance increases due to low humidity, the residual potential increases similarly to the above, causing fogging in the image.

Furthermore, since the undercoat layer is required to have various properties in addition to the properties listed above, if the undercoat layer is made of only a single resin as in the past, it may not be good. The problem was that it was difficult to obtain.

In addition, in order to lower the electrical resistance of such an undercoat layer, the thickness of the resin layer that becomes the undercoat layer is made very thin, and if necessary, metal powder such as nickel, copper, silver, etc. Dispersing conductive powder consisting of a resin into a resin has been carried out.

However, if the thickness of the resin layer that becomes the undercoat layer is made thin, it has the disadvantage that other performances as an undercoat layer cannot be achieved sufficiently.On the other hand, when metal powder etc. are dispersed, However, since the metal particles are rough, the surface properties of the undercoat layer are deteriorated.

[Purpose of the Invention] This invention was made in order to solve the above-mentioned drawbacks of conventional photoreceptors in a photoreceptor in which an undercoat layer is provided between a conductive support and a photoconductive layer. The purpose of the present invention is to use a layer having excellent properties such as electrical properties and surface smoothness, and to provide a photoreceptor having excellent overall electrophotographic properties.

[Means for Solving the Problems] In the photoreceptor according to the present invention, the undercoat layer formed between the conductive support and the photoconductive layer contains silicon carbide.

In this way, when the undercoat layer contains silicon carbide, the volume resistivity of the undercoat layer decreases because silicon carbide has conductivity, and the film thickness of the undercoat layer can be reduced without increasing the residual potential. It can be made thicker, and the surface of the conductive support can be sufficiently protected, and defects on the surface of the conductive support can be covered and the surface can be finished smoothly.

In addition, the formation of such an undercoat layer suppresses the injection of carrier from the conductive support into the photoconductive layer, which is a problem especially in reader printers and laser printers that perform reversal development. The occurrence of black spots in the area can be effectively prevented.

Furthermore, when a photoreceptor on which such an undercoat layer is formed is used in an electrophotographic device that uses coherent light such as a laser beam, the laser light incident on the photoreceptor may damage the surface of the undercoat layer. The reflected light and the incident light will be reflected somewhat diffusely, and interference fringes will no longer occur in the image due to interference between the reflected light and the incident light.

Next, when the undercoat layer contains silicon carbide and is formed on a conductive support, the silicon carbide is usually finely divided and used as a binder that constitutes the undercoat layer. It is formed by dispersing it in a resin solution and applying this dispersion onto a conductive support.

Here, as the silicon carbide to be contained in the undercoat layer, it is preferable to use β-crystal type fine powder with good conductivity, and this fine powder is preferably used in order to form the undercoat layer smoothly. Those having an average particle size of 1 μm or less, more preferably 0.01 to 0.5 μm are used.

Furthermore, if the amount of silicon carbide contained in the undercoat layer is less than 20% by weight, the volume resistivity of the undercoat layer will generally not be sufficiently reduced, which may lead to an increase in residual potential. If the undercoat layer exceeds 80% by weight, the undercoat layer may not be formed homogeneously and image (A) defects may occur. Therefore, the content should preferably be 20 to 80% by weight. The volume resistivity of the silicon-containing undercoat layer is set to be 10 6 to 10 12 Ω·Ω.

In addition, in order to control the volume resistivity of the undercoat layer, it is also possible to heat-process a part of the silicon carbide contained to change it into silicon dioxide having high electrical resistance, and to use this in combination.

Regarding the thickness of this undercoat layer, if it is too thin, the desired effect as an undercoat layer cannot be obtained, while if it is too thick, the electrical resistance of the undercoat layer will become high and residual potential will accumulate. The film thickness is preferably about 1 to 30 μm, more preferably about 5 to 25 μm.

On the other hand, the resins constituting the undercoat layer include conventionally known polyvinyl alcohol, polyvinyl methyl ether,
In addition to using poly-N-vinylimidazole, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, gelatin, polyamide, etc.
- Thermoplastic resins such as polyester resin, acrylic resin, vinyl acetate resin, vinyl chloride-vinyl acetate resin, polyvinyl butyral resin, Alkyra F resin, melamine resin, urethane resin, epoxy resin, silicone resin, phenol resin, etc. Any of these thermosetting resins may be used, and is appropriately selected and used in consideration of adhesion to the conductive support, dispersibility, etc. Among these, acrylic-melamine resins, urethane resins, and the like are particularly preferred in terms of adhesiveness and coatability.

Next, when dispersing the silicon carbide fine powder as described above in a solution of such a resin and coating it on a conductive support, a dip coating method, a spray coating method, a spinner coating method, a bead coating method can be used. , a wire bar coating method, a blade coating method, a roller coating method, a curtain coating method, and other coating methods.

The dispersion thus applied onto the conductive support is then dried to form an undercoat layer containing silicon carbide.

In addition, this undercoat layer may contain zinc oxide, calcium oxide, barium oxide, titanium oxide, carbon oxide,
Non-conductive white powders such as barium sulfate, calcium sulfate, barium carbonate, magnesium carbonate, etc. may be added.
When the non-conductive white powder is added in this way, the light reflectance of the undercoat layer increases, and the sensitivity of the photoreceptor improves.

On the other hand, conductive supports forming such an undercoat layer include sheets or drums made of copper, aluminum, silver, iron, nickel, etc. foils or plates, and plastic films made of these metals. A layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide is formed by coating or vapor deposition on a support such as paper or plastic film. etc.

Next, the photoconductive layer formed on the undercoat layer can be any commonly used photoconductive layer, such as a photoconductive layer formed by vapor-depositing an inorganic photoconductive material such as Se or CdS. , CdS, ZnO.

Examples include those in which conductive powder such as TiO2 is dispersed and applied in an insulating binder resin, and organic photoconductive materials such as polyvinylcarbazole, anthracene, and phthalocyanine are applied as is or mixed with an insulating binder resin. Furthermore, a functionally separated type in which the functions of the photoconductive layer are separated and a charge generation layer and a charge transport layer are laminated may be used.

Note that, before forming the photoconductive layer on the undercoat layer in this manner, it is preferable to provide an intermediate layer on the undercoat layer in order to more reliably prevent injection of carriers. This intermediate layer includes polyvinyl alcohol, polyvinyl butalal,
A thin film made of water-soluble resins such as polyvinyl methyl ether, polyacrylic acids, casein, starch, gelatin, methylcellulose, ethylcellulose, polyglutamic acid, and resins such as polyimide, polyamide, epoxy resin, poly-N-vinylimidazole, polyurethane, etc. Form on the pull layer.

Further, a protective layer may be provided on the surface of the photoconductive layer to protect the photoconductive layer.

[Effects of the Invention] As described above, in the photoreceptor according to the present invention, silicon carbide is contained in the undercoat layer formed on the conductive support to reduce the volume resistivity of the undercoat layer. ,
Good images can now be obtained without fogging caused by an increase in residual potential.

In addition, since the volume resistivity of the undercoat layer is low, the thickness of the undercoat layer can be set with considerable flexibility, and the surface of the conductive support can be sufficiently protected. It becomes possible to cover defects on the surface and make the surface smooth.

In addition, this undercoat layer suppresses the injection of carrier from the conductive support to the photoconductive layer, and prevents the occurrence of black spots on blank areas, which is a particular problem with reader printers and laser printers that perform reversal development. It has become suppressed.

Furthermore, when used in an electrophotographic device that uses coherent light such as a laser beam, the laser beam is slightly diffusely reflected on the surface of this undercoat layer, resulting in interference fringes due to interference between the reflected light and the incident light. The occurrence of this problem has been suppressed, and high-quality images can now be obtained.

[Example] Next, specific examples of the present invention will be described, and comparative examples will be given to clarify that the examples of the present invention are superior.

Husband 1''L In this example, an aluminum drum was used as the conductive support.

Next, thermosetting acrylic resin Acrydic A405
(manufactured by Dainippon Ink ■) and 3 parts by weight of β-type random silicon carbide micronized to 1 μm or less are dispersed in 100 parts by weight of toluene, and this dispersion is placed on the aluminum drum mentioned above. It was applied to a thickness of 3 μm and dried to form an undercoat layer containing silicon carbide.

Then, a charge generation layer using τ-type metal-free phthalocyanine as a charge generation material was formed on this undercoat layer. In forming this charge generation layer, the above τ
1 part by weight of mold-free metal phthalocyanine, 1 part by weight of polyester resin Vylon 200 (manufactured by Toyobo ■), and 100 parts by weight of cyclohexanone were placed in a ball mill bot.
After dispersion for 4 hours, this dispersion was applied onto the undercoat layer and dried to form a charge generation layer having a thickness of 0.3 μm.

Next, in forming a charge transport layer on this charge generation layer, a butadiene compound represented by the following chemical formula (2) was used as a charge transport material.

Then, 10 parts by weight of the above butadiene compound and -1300 (manufactured by Yojin Kasei) were added to the polycarbonate resin Panlite.
10 parts by weight were dissolved in a solvent consisting of 180 parts by weight of TeI to bovine dorofuran, and this solution was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 15 μm.

In this way, a functionally separated laminated photoreceptor was produced in which a silicon carbide-containing undercoat layer, a charge generation layer, and a charge transport layer were laminated on an aluminum drum.

and fi Also in this example, an aluminum drum was used as the conductive support.

Then, 10 parts by weight of polystyrene resin Dialex 307 (manufactured by Mitsubishi Monsando Kasei ■) and 4 parts by weight of β-type random silicon carbide finely divided to 1 μm or less were dispersed in 100 parts by weight of toluene. It was coated onto the above aluminum drum to a thickness of about 5 μm and dried to form an undercoat layer containing silicon carbide.

Next, 50 parts by weight of copper phthalocyanine and 50 parts by weight of tetranitrocopper phthalocyanine were added to 500 parts by weight of 98% concentrated sulfuric acid and dissolved with thorough stirring.
After precipitating a photoconductive material composition of 00 parts by weight of copper phthalocyanine and tetranitrocopper cyanine, this was filtered, washed with water, and dried at 120° C. under reduced pressure.

15 parts by weight of the photoconductive material composition thus obtained, 20 parts by weight of polyester resin, 20 parts by weight of polycarbonate resin, and 20 parts by weight of P-diethylaminobenzaldehyde diphenylhydrazone were mixed together with 100 parts by weight of tetrahydrofuran in a ball mill. put it in a pot,
These were kneaded for 48 hours to prepare a photoconductive paint.

Then, this photoconductive paint is applied onto the undercoat layer and dried to produce a photoreceptor having a photoconductive layer with a thickness of 15 μm formed on the undercoat layer.

In this example as well, an aluminum drum was used as the conductive support, and thermosetting acrylic resin Acrydic A was used.
-405 (manufactured by Dainippon Ink ■), 6 parts by weight of silicon carbide, and 4 parts by weight of zinc oxide are dispersed together with 150 parts by weight of toluene, and this dispersion is placed on the aluminum drum so as to have a thickness of about 10 μm. and dried to form a silicon carbide-containing undercoat layer.

Next, in forming a charge generation layer on this undercoat layer, a disazo pigment represented by the following chemical formula (2) was used as a charge generation material.

(n) Then, 1 part by weight of this disazo pigment, 1 part by weight of polyester resin Vylon 200 (manufactured by Toyobo ■), and 100 parts by weight of cyclohexane were placed in a ball mill bot.
Dispersion was carried out for 4 hours, and this dispersion was placed on the undercoat layer at 0.00%.
It was applied to a thickness of 5 μm and dried to form a charge generation layer.

Next, in forming a charge transport layer on this charge generation layer, a hydrazone compound represented by the following chemical formula (2) was used as a charge transport material.

Then, 10 parts by weight of the above hydrazone compound and -1300 (manufactured by Yojin Kasei) were added to the polycarbonate resin Panlite.
This solution was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 18 μm.

In this manner, a functionally separated laminated photoreceptor was produced in which a silicon carbide-containing undercoat layer, a charge generation layer, and a charge transport layer were laminated on an aluminum drum.

K1 Randomization In this example, an intermediate layer was formed between the undercoat layer and the charge generation layer in the photoreceptor of Example 3 above.

In forming this intermediate layer, copolymerized nylon CM8
000 (manufactured by Toshi ■) in a mixed solvent consisting of 5 parts by weight of methanol and 50 parts by weight of n-butanol, and this solution was applied onto the undercoat layer to form a film with a thickness of 0.5 μm.
An intermediate layer was formed.

A laminated photoreceptor was produced in the same manner as in Example 3 except for forming an intermediate layer.

In L1 Milk Comparative Example 1, no undercoat layer was provided, except for Example 1.
A photoreceptor was produced in exactly the same manner as that described above.

In Comparative Example 2, a photoreceptor was produced in the same manner as in Example 1 except that the undercoat layer did not contain silicon carbide.

In Comparative Example 3 of L11, to form the undercoat layer, 5 parts by weight of copolymerized nylon C) 48000 (manufactured by Higashishabata) was dissolved in a mixed solvent consisting of 50 parts by weight of methanol and 50 parts by weight of n-butanol. This was coated onto an aluminum drum to a thickness of 0.5 μm and dried to form an undercoat layer. A photoreceptor was produced in the same manner as in Example 1 except for this.

Examples 1 to 4 and Comparative Examples 1 to 4 obtained as above
Each of the photoreceptors in Example 1 was incorporated as a photoreceptor in a powder image transfer type electrophotographic copying machine 470Z manufactured by Minolta Camera ■.
．． -6 for each photoconductor of 3.4 and Comparative Examples 1 to 3.
The photoconductor of Example 2 was charged with a +6KV corona discharge, and the initial surface potential Vo of each photoconductor was set to 172 KV.
The half-reduced exposure amount E1/2 (Ix-sec>
, initial surface potential V when left in the dark for 1 second
. The dark decay rate DDR1 (%) of each photoreceptor and the image quality when copied using each photoreceptor were investigated.

The results are shown in Table 1 below. Regarding the image quality, the same table shows good image quality as ○ and problematic image quality as x.

Table 1 Next, for the photoreceptors of Examples 1 and 3 and Comparative Examples 1 to 3, the initial surface potential V of each photoreceptor is shown. While setting the voltage to -750V, the developing bias vb was set to ~500V to perform a reversal phenomenon, and black spots in a blank area and white spots in a solid black area on the image were measured.

The results are shown in Table 2 below. In the same table, ○ means good, × means there is a problem, and XX means very bad.

As is clear from this result, when the photoreceptors of Examples 1 and 3 were used, black spots and black spots on the white paper area during reversal development were more pronounced than when the photoreceptors of Comparative Examples 1 to 3 were used. The occurrence of white spots in solid areas has been reduced, and high-quality images can now be obtained.

Claims (1)

[Scope of Claims] 1. A photoreceptor comprising at least an undercoat layer containing silicon carbide and a photoconductive layer formed on a conductive support. 2. The silicon carbide has β-type crystals, and the particle size is 1.
The photoreceptor according to claim 1, which has a particle diameter of μm or less.