JPH11288121A - Electrophotographic photoreceptor and electrophotographic device equipped with electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has durability against wear or scratches of the photoreceptor surface by friction, which does not cause decrease in the surface resistance due to deposition of products by corona discharge in repeated electrophotographic processes, and which can maintain high quality images even in a high humidity environment, and to provide an electrophotographic device having the electrophotographic photoreceptor. SOLUTION: This electrophotographic photoreceptor is produced by successively depositing a surface photosensitive layer and a protective layer on a conductive supporting body. The surface protective layer consists of a hardening resin by the combination of a radical polymerizable compd. and an ion polymerizable compd. Thus, the obtd. photoreceptor has excellent environmental stability and can produce high quality image even after repeatedly used. The electrophotographic device is equipped with this electrophotographic photoreceptor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member having a surface protective layer and an electrophotographic apparatus.

[0002]

2. Description of the Related Art An electrophotographic photoreceptor is required to have required sensitivity, electrical characteristics and optical characteristics according to an electrophotographic process to be used, but it is used over and over again. In the photoreceptor, the surface layer of the photoreceptor, that is, the layer farthest from the support, is subjected to direct electrical and mechanical external forces such as charging, exposure, development, transfer, and cleaning. Is required. Specifically, there is a demand for durability against surface abrasion and scratches caused by rubbing, surface deterioration due to ozone generated during charging, and the like. On the other hand, there is a problem that toner is adhered to the surface layer due to repetition of toner development and cleaning, and it is required to improve the cleaning property of the surface layer.

Attempts have been made to provide a surface protective layer containing a resin as a main component in order to satisfy the characteristics required for the above-mentioned surface layer. For example, as proposed in JP-A-57-30846, a protective layer in which resistance is controlled by adding a metal oxide as a conductive powder has been proposed.
The main purpose of dispersing the metal oxide in the protective layer for the electrophotographic photosensitive member is to control the electrical resistance of the protective layer itself, and to prevent an increase in the residual potential in the photosensitive member during the repetition of the electrophotographic process. Is the purpose.

Further, it has been shown that a suitable resistance value of a protective layer for an electrophotographic photosensitive member is 10 ¹⁰ to 10 ¹⁵ Ω · cm. However, in the resistance value in the above range, the electric resistance of the protective layer is easily affected by ionic conduction,
For this reason, the electrical resistance tends to greatly change due to changes in the environment.

[0005] Furthermore, corona products such as ozone and nitrogen oxides generated by repetitive charging under high humidity, in particular,
Adhering to the surface causes a reduction in the surface resistance of the photoreceptor, causing problems such as image deletion.
In addition, the releasability of the binder resin itself and the durability against abrasion and scratches due to rubbing are not sufficient for prolonging the service life, and a material showing satisfactory electrophotographic properties as a protective layer has not yet been obtained. It was the current situation.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photosensitive member which meets the above-mentioned requirements. That is, an object of the present invention is to provide an electrophotographic photoreceptor having excellent slipperiness and having durability against abrasion and scratches on the surface due to rubbing.

Another object of the present invention is to provide an electrophotographic photoreceptor capable of maintaining a high quality image even under high humidity without a decrease in surface resistance due to the adhesion of corona products generated in a repetitive electrophotographic process. Is to provide.

Another object of the present invention is to provide an electrophotographic apparatus provided with the above electrophotographic photosensitive member.

[0009]

According to the present invention, in an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer laminated in this order on a conductive support, the surface protective layer comprises a radical polymerizable compound and an ionic polymerizable compound. An electrophotographic photoreceptor formed of a combined curable resin is provided.

Further, according to the present invention, in an electrophotographic apparatus comprising an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit and a transferring unit, the photosensitive member comprises a photosensitive layer and a surface protective layer on a conductive support in this order. There is provided an electrophotographic apparatus provided with an electrophotographic photoreceptor laminated and formed of a curable resin in which the surface protective layer is a combination of a radical polymerizable compound and an ion polymerizable compound.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photoconductive layer and a surface protective layer on a conductive substrate. The radical polymerizable compound used in the protective layer is a monomer or an oligomer that starts a polymerization reaction by a suitable radical initiator that generates a radical by heat or ultraviolet rays. In general, acrylics are widely used, and the types of monomers include monofunctional and polyfunctional acrylates.

The basic skeleton is of an aliphatic type, an alicyclic type, an aromatic type, or a type containing a functional group such as a hydroxyl group, an aryl group, a glycidyl group, a carboxyl group, or a Cl or Br group. Further, a special acrylate monomer containing phosphorus or other metal can be selected. For oligomers, polyester, urethane, polyether, epoxy,
Polybutadiene-based, silicone-based and the like are of various types. On the other hand, as the non-acrylic type, unsaturated polyester type, polybutadiene type, polyene-polythiol type and the like are used. Each of these monomers and oligomers may be used alone, or two or more of them may be mixed.

The radical polymerization initiator used in the radically polymerizable compound of the present invention may be any compound capable of generating a radical upon irradiation with heat or light, such as arylalkylketones, oximuketins, acylphensphine oxides, Benzoin ethers, thiobenzoic acid S-
Examples include, but are not limited to, phenyl, titanocenes, aromatic ketones, thioxanthones, azo compounds, organic oxide compounds, and the like. In addition to using these alone, it is also possible to mix two or more.

The ionic polymerizable compound used in the present invention is a monomer or an oligomer which starts ionic polymerization by using an ionic initiator which generates a cation or an anion catalyst by light irradiation. In the present invention, examples of vinyl ether monomers and oligomers used as particularly preferred cationic polymerizable compounds among these are shown in Table 1, but are not limited thereto. These may be used alone or in combination of two or more.

[0015]

[Table 1]

Examples of the cationic initiator used in the ionic polymerizable compound of the present invention include, as shown in Table 2, diazonium compounds, sulfonium compounds, iodonium compounds, metal complex compounds, arylsilanol aluminum complexes and the like. However, the present invention is not limited to these. These can be used alone or in combination of two or more.

[0017]

[Table 2]

In the present invention, the mixing ratio between the radical polymerizable compound and the ionic polymerizable compound is as follows:

[0019]

(Equation 2) Can be appropriately selected within the range.

The surface protective layer of the present invention is preferably a film in which ultrafine particles of a conductive metal oxide are dispersed in a curable resin. Examples of the conductive metal oxide used in the present invention include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide. One or more of the fine particles can be used in combination.

Since these conductive fine particles and the above-mentioned curable resin (binder resin) are factors that determine the resistance as the surface protective layer, their ratios are carefully determined. In the present invention, the ratio of the conductive fine particles in the protective layer is one of the factors directly determining the resistance of the protective layer.
It is preferably in the range of 0 ¹⁰ to 10 ¹⁵ Ω · cm. Therefore, the ratio between the conductive fine particles and the binder resin is determined within the range of the resistance.

Various additives can be added to the protective layer for the purpose of improving the dispersibility and smoothness of the conductive fine particles. In particular, for improving the dispersibility, it is very effective to perform a surface treatment on the conductive fine particles. As the surface treatment agent, a fluorine-containing silane coupling agent, a fluorine-modified silicone oil, a fluorine-based surfactant and a fluorine-based graft polymer are particularly preferable.

In the protective layer, a fluorine-containing resin can be added for the purpose of improving smoothness. Examples of the fluorine atom-containing resin include tetrafluoroethylene resin, trifluoroethylene resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorinated ethylene chloride resin and copolymers thereof. 1 from inside
It is preferable to appropriately select the species or two or more species, and particularly preferred are a tetrafluoroethylene resin and a vinylidene fluoride resin. The ratio of the fluorine atom-containing resin particles in the protective layer is 5
%, Preferably in the range of 10 to 60% by weight. The molecular weight of the resin and the particle size of the particles can be appropriately selected and are not particularly limited.

In the present invention, additives such as an antioxidant may be added to the protective layer for the purpose of improving weather resistance. In this way, the protective layer is formed by applying and curing a solution in which the binder resin and the conductive metal oxide are dispersed. The thickness of the protective layer of the present invention is suitably in the range of 0.2 to 7 μm, and more preferably in the range of 0.5 to 5 μm.

An intermediate layer may be used between the photosensitive layer and the protective layer for the purpose of improving smoothness and weather resistance, but the binder resin is a polyester resin, a polycarbonate resin, or the like.
Polyurethane resin, phenolic resin, epoxy resin, melamine resin, polystyrene resin, polyvinyl butyral resin, polyamide resin, acrylic resin, styrene-butadiene copolymer, styrene-acrylic copolymer, polyacrylic acid and its esters, polymethacrylic acid and Examples thereof include esters, cellulose, casein, and gelatin. The thickness of the intermediate layer is from 0.01 to 10 μm, preferably from 0.1 to 3 μm. In addition, the intermediate layer may further contain an antioxidant, a conductive material, an ultraviolet absorber, and a surfactant.

The photoconductive layer of the electrophotographic photoreceptor may be composed of a single layer containing both a charge generating substance and a charge transporting substance, or a laminated type comprising a charge generating layer and a charge transporting layer laminated on a conductive substrate. Is one of As the structure of the laminated photosensitive layer, there are a structure in which a charge generation layer and a charge transport layer are laminated on a conductive substrate in this order, and a structure in which a charge transport layer and a charge generation layer are laminated in this order.

The conductive substrate to be used is selected from those having conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc, stainless steel or the like, which is formed into a drum or sheet shape; A metal foil laminated on a plastic film, aluminum, indium oxide, tin oxide, etc. deposited on a plastic film, a metal, plastic film, paper provided with a conductive layer by applying a conductive substance alone or with a binder resin And the like.

The charge transport layer of the laminated photoreceptor is composed of a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene, or phenanthrene in the main chain or side chain, or a nitrogen-containing compound such as indole, carbazole, oxadiazole, or pyrazoline. It is formed by using a coating solution in which a charge transporting substance such as a ring compound, a hydrazone compound, a styryl compound or the like is dissolved in a resin having a film forming property. Examples of the resin having a film forming property include polyester, polycarbonate, polystyrene, and polymethacrylate. The thickness of the charge transport layer is 5 to 40 μm, preferably 10 to 30 μm.

The charge generating layer of the laminated photoreceptor is made of an azo pigment such as stern red and diane blue, a quinone pigment such as perenquinone and anthantrone, a quinocyanine pigment, a perylene pigment, an indigo pigment such as indigo and thioindigo,
A charge-generating substance such as a phthalocyanine pigment is dispersed in a binder resin such as polyvinyl butyral, polystyrene, polyvinyl acetate, and an acrylic resin, and the dispersion is applied or the pigment is formed by vacuum evaporation. The thickness of such a charge generation layer is 5 μm or less, preferably 0.05 to 3 μm.

In the present invention, an undercoat layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer. The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, alcohol-soluble amide, polyurethane, gelatin or the like. The thickness of the undercoat layer is 0.1 to 3 μm
Is appropriate.

As described above, the electrophotographic photoreceptor of the present invention has an electrophotographic photoreceptor in which a protective layer made of a curable resin in which a radically polymerizable compound and an ionic polymerizable compound are combined is formed on a photosensitive layer. It is. This makes it possible to form a protective layer that is excellent in durability and suppresses a decrease in surface resistance due to corona product adhesion during charging even under high humidity, resulting in image defects due to scratches and images under high humidity. It has become possible to provide high quality electrophotographic photoreceptors without flow.

The electrophotographic photoreceptor of the present invention is applicable to general electrophotographic devices such as copiers, laser beam printers, LED printers, and liquid crystal shutter printers.

[0033]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited by these examples. In the examples, "parts" indicates parts by weight.

Example 1 An alcohol-soluble polyamide resin [trade name; Amilan CM-
8000, manufactured by Toray Industries, Inc.] 10 parts, methoxymethylated 6 nylon resin [trade name: Toresin EF-30T, manufactured by Teikoku Science Co., Ltd.] 30 parts in a mixed solvent of 150 parts of methanol and 150 parts of butanol. The dissolved preparation was applied by dip coating and dried at 90 ° C. for 10 minutes to form an undercoat layer having a thickness of 1 μm.

Next, 4 parts of a disazo pigment represented by the following structural formula:

[0036]

Embedded image After dispersing 2 parts of butyral resin [trade name: S-Rex BL-S, manufactured by Sekisui Chemical Co., Ltd.] and 100 parts of cyclohexanone for 48 hours using a sand mill, 100 parts of tetrahydrofuran is added, and a dispersion for the charge generation layer is added. Was prepared. This dispersion is dip-coated on the undercoat layer,
After drying at 15 ° C. for 15 minutes, a charge generation layer having a thickness of 0.15 μm was formed.

Next, 10 parts of a styryl compound having the following structural formula

[0038]

Embedded image And polycarbonate resin [trade name: Iupilon Z-2]
00, manufactured by Mitsubishi Gas Chemical Co., Ltd.] was dissolved in a mixed solvent of 20 parts of dichloromethane and 60 parts of monochlorobenzene, and this solution was applied onto the charge generating layer by dip coating.
After drying at 0 ° C. for 60 minutes, a charge transport layer having a thickness of 18 μm was formed.

Next, a preparation for the protective layer was prepared by the following procedure. Antimony-containing tin oxide having an average particle size of 0.02 μm [T-1; manufactured by Mitsubishi Materials Corporation] 10
After milling 0 parts, 30 parts of (3,3,3-trifluoropropyl) trimethoxysilane [manufactured by Shin-Etsu Chemical Co., Ltd.] and 300 parts of a 95% ethanol-5% aqueous solution, the solution is filtered and washed with ethanol. After drying, 120 ℃
The surface treatment of the tin oxide fine particles was performed by heat treatment for 1 hour.

80 parts of an acrylic monomer compound represented by the following structural formula was added to the surface-treated tin oxide fine particles,

[0041]

Embedded image 20 parts of a vinyl ether monomer represented by the following structural formula,

[0042]

Embedded image 8 parts of a radical polymerization initiator represented by the following structural formula,

[0043]

Embedded image 1 part of a cationic polymerization initiator represented by the following structural formula,

[0044]

Embedded image And 300 parts of ethanol and 9
Disperse for 6 hours and add tetrafluoroethylene resin particles
[Product name: Lubron L-2, manufactured by Daikin Industries, Ltd.] 1
Then, 00 parts were mixed and further dispersed for 4 hours by a sand mill to prepare a preparation liquid for a protective layer.

Dip coating was carried out on the charge transport layer using this prepared liquid, and 500 mW /
UV irradiation for 30 seconds at a light intensity of 3 cm ²
Was formed to obtain a photoreceptor.

The electrophotographic photosensitive member produced in this manner was mounted on a copying machine in which a charging-exposure-development-transfer-cleaning process was repeated in a cycle of 1.5 seconds.
Evaluation of electrophotographic properties at room temperature and humidity of 50 ° C. and 50%, image evaluation at low temperature and low humidity of 10 ° C. and 15%, and image evaluation at high temperature and high humidity of 35 ° C. and 85%. Was done.
Further, the image was repeatedly imaged and durable 70,000 times under normal temperature and normal humidity.

The dark area potential is the surface potential of the photosensitive member when discharged at a corona discharge voltage of -5 kV. The larger the value, the better the charging ability, and the sensitivity is -7.
Indicates the amount of exposure necessary to attenuate from 00V to -200V.

As a result, the photoreceptor of the present invention was a photoreceptor having no protective layer as shown in Comparative Example 1, and a photoreceptor in which no ionic polymerizable compound was mixed in the protective layer as shown in Comparative Examples 2 and 3.
The sensitivity and the residual potential were the same as those of the photoreceptor having a large mixing ratio of the ionic polymerizable compound, but no image defect or image deletion was observed during the durability test. And 7
A stable image was able to be maintained even in an image repetition durability test for 10,000 times. Table 3 shows the results.

Example 2 Example 1 was the same as Example 1 except that 30 parts of the acrylic monomer compound, 70 parts of the vinyl ether monomer compound, 3 parts of the radical polymerization initiator and 3.5 parts of the cationic polymerization initiator were used. In the same manner, an electrophotographic photosensitive member was prepared and evaluated. Table 3 shows the results.

Example 3 An electrophotographic photosensitive member was prepared and evaluated in exactly the same manner as in Example 1 except that the vinyl ether monomer compound in Example 1 was changed to the one having the following structural formula. Table 3 shows the results.

[0051]

Embedded image

Example 4 An electrophotographic photoreceptor was prepared and evaluated in exactly the same manner as in Example 1 except that the vinyl ether monomer compound in Example 1 was changed to that of the following structural formula. Table 3 shows the results.

[0053]

Embedded image

(Example 5) In Example 1, 99 parts of an acrylic monomer compound and a vinyl ether monomer compound 1
An electrophotographic photoreceptor was prepared and evaluated in exactly the same manner as in Example 1 except that the parts were 10 parts, a radical polymerization initiator of 10 parts, and a cationic polymerization initiator of 0.05 part. Table 3 shows the results.

(Comparative Example 1) An electrophotographic photosensitive member was prepared and evaluated in exactly the same manner as in Example 1 except that the protective layer was omitted. As a result, as shown in Table 3, the initial electrophotographic characteristics were good, but when a durability test was performed, a good image could not be obtained from around 7,500 sheets.

(Comparative Example 2) The same procedure as in Example 1 was repeated except that the ionic polymerizable compound was not mixed with the acrylic monomer compound.
And an electrophotographic photoreceptor was prepared and evaluated in exactly the same manner as in Example 1 except that the amount of the radical polymerization initiator was changed to 10 parts. As a result, as shown in Table 3, the initial electrophotographic characteristics were good, but when a durability test was performed, a good image could not be obtained from around 30,000 sheets. Further, image deletion occurred under high temperature and high humidity.

Comparative Example 3 Example 1 was repeated except that the acrylic monomer compound was 20 parts, the vinyl ether monomer compound was 80 parts, the radical polymerization initiator was 2 parts, and the amount of the ionic polymerization initiator was 4 parts. An electrophotographic photoreceptor was prepared and evaluated in exactly the same manner as described above. As a result, Table 3
As shown in Fig. 5, the initial electrophotographic characteristics were good, but when a durability test was performed, a good image could not be obtained from around 10,000 sheets. Further, image deletion occurred under high temperature and high humidity.

[0058]

[Table 3]

[0059]

As described above, by forming the protective layer with a curable resin in which a radical polymerizable compound and an ionic polymerizable compound are combined, the durability is improved, and even under high temperature and high humidity. It has become possible to produce an electrophotographic photosensitive member that does not cause image deletion.

The use of the electrophotographic photoreceptor of the present invention is excellent in environmental stability and can provide a high-quality image even after repeated use.

Claims (8)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer and a surface protective layer laminated on a conductive support in this order, wherein the surface protective layer is formed of a curable resin in which a radical polymerizable compound and an ionic polymerizable compound are combined. An electrophotographic photoreceptor characterized in that: 2. The electrophotographic photoreceptor according to claim 1, wherein said radical polymerizable compound is at least one compound selected from acrylic monomers and acrylic oligomers. 3. The electrophotographic photosensitive member according to claim 1, wherein the ionic polymerizable compound is cationically polymerizable. 4. The electrophotographic photosensitive member according to claim 1, wherein the ionic polymerizable compound is at least one compound selected from a vinyl ether monomer and a vinyl ether oligomer. 5. The electrophotographic photoreceptor according to claim 1, wherein the mixing ratio of the radical polymerizable compound and the ionic polymerizable compound satisfies the following relationship. (Equation 1) 6. The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer is a film in which ultrafine particles of a conductive metal oxide are dispersed in the curable resin. 7. The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer is a film in which fine particles of a fluorine atom-containing resin are dispersed in the curable resin. 8. An electrophotographic photoreceptor, charging means, exposure means,
In an electrophotographic apparatus comprising a developing unit and a transfer unit,
An electrophotography in which the photoconductor has a photosensitive layer and a surface protective layer laminated in this order on a conductive support, and the surface protective layer is formed of a curable resin in which a radical polymerizable compound and an ionic polymerizable compound are combined. An electrophotographic device provided with a photoreceptor.