JPH04329549A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a sensitive body having high sensitivity and excellent repetitive characteristics in electrification and exposure even at low temp. and humidity by using alcohol-soluble nylon resin as the base of an underlayer and incorporating aluminate into the underlayer. CONSTITUTION:An electric charge generating layer and an electric charge transferring layer are successively laminated on an underlayer based on alcohol- soluble nylon resin and contg. aluminate. The nylon resin used is a nylon copolymer or modified nylon, preferably the nylon copolymer. Since the nylon resin is dissolved only in lower aliphatic alcohol such as methanol or ethanol, a solvent other than lower alcohol is used as a solvent for coating when the electric charge generating layer is formed on the underlayer. The aluminate is a compd. represented by a general formula xM12O.yAl2O3.zH2 and sodium aluminate or potassium aluminate may be used.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to a laminated electrophotographic photoreceptor having excellent charging and exposure repetition characteristics.

0002

2. Description of the Related Art Conventionally, electrophotographic photoreceptors having photosensitive layers containing inorganic photoconductors such as selenium, zinc oxide, and cadmium sulfide as main components have been widely known. However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. In addition, selenium and cadmium sulfide are particularly toxic, so there are restrictions in production and handling.

On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, and easy to handle.
In addition, they generally have many advantages over selenium photoreceptors, such as superior thermal stability, and have attracted much attention in recent years. Such organic photoconductive compounds include poly-N
-Vinylcarbazole is well known, and this and 2,
Japanese Patent Publication No. 10469/1989 describes an electrophotographic photoreceptor having a photosensitive layer containing as a main component a charge transfer complex formed with a Lewis acid such as 4,7-trinitro-9-fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity, film formability, and durability.

In response, low molecular weight organic photoconductors typified by hydrazones and pyrazolines have been proposed. By combining these with an appropriate binder,
Although significant improvements have been made in film formability, sensitivity and durability are still far from satisfactory. For this reason, in recent years, a laminated photoreceptor has been proposed in which the carrier generation function and carrier transport function are shared by separate substances. By adopting this structure, the charging characteristics and sensitivity are greatly improved.In particular, an azo pigment with high carrier generation ability is used in the charge generation layer, and this is combined with a charge transfer substance with high carrier transport ability such as a hydrazone compound. As a result, some photoreceptors with sensitivity close to that of inorganic photoreceptors such as selenium have appeared. As a result, the current situation is that electrophotographic photoreceptors containing these types of organic photoconductive compounds as main components are beginning to make significant inroads into the fields of copying machines, optical printers, and the like.

[0005] Electrophotographic photoreceptors undergo repeated processes such as charging, exposure, and neutralization in copiers, printers, etc., and fluctuations in the initial potential after charging and the residual potential after neutralization affect the output image. must be suppressed as much as possible. However, in general, these photoreceptors suffer from fatigue due to repeated charging and exposure, resulting in a decrease in chargeability or an increase in residual potential.

In order to compensate for the above-mentioned drawbacks, a method has been proposed in which an undercoat layer is provided between the conductive substrate and the photosensitive layer. For example, JP-A-48-47344, JP-A No. 52-25638.
No. 58-30757, No. 58-63945, No. 58-98739, and No. 60-66258 have a nylon resin undercoat layer;
No. 32 and No. 52-10138 disclose a maleic acid resin undercoat layer, and JP-A-58-105155 discloses a polyvinyl alcohol resin undercoat layer.

[0007] A method has also been proposed in which the electrical resistance of the undercoat layer is controlled by containing various conductive additives in the undercoat layer. For example, JP-A-51-65942 discloses an undercoat layer in which carbon or chalcogen-based substances are dispersed in a curable resin, and JP-A-52-82238 discloses an isocyanate-based undercoat layer in which a quaternary ammonium salt is added. A thermopolymer undercoat layer using a hardening agent is disclosed in JP-A-55-1180451.
In the publication, an undercoat layer containing a resistance adjusting agent was disclosed in Japanese Patent Application Laid-open No. 5
8-58556 discloses an undercoat layer in which tin or aluminum oxide is dispersed, and JP-A-58-93063, JP-A-60-97363, and JP-A-60-111255 disclose an undercoat layer in which conductive particles are dispersed. Subbing layers are each disclosed.

However, the conventional electrophotographic photoreceptor is
It is still insufficient to reduce chargeability and increase residual potential due to fatigue due to repeated charging and exposure, and there is also the problem that the increase in residual potential is particularly large at low temperatures and low humidity, so further improvements are desired. It was rare.

[0009]

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor whose characteristics are stabilized even under low temperature and low humidity when used repeatedly in an electrophotographic process. be.

0010

[Means for Solving the Problems] The present inventors have conducted various studies in order to achieve the above object, and as a result, the present inventors have found that an alcohol-soluble nylon resin is used as a main component between the conductive support and the charge generation layer. It has been found that by providing an undercoat layer and containing an aluminate in this undercoat layer, a laminated electrophotographic photoreceptor can be obtained that exhibits extremely excellent charging and repeated exposure characteristics even at low temperature and low humidity.

[0011] The constituent elements of the present invention will be explained in detail below. Alcohol-soluble nylon resins used in the present invention can generally be classified into two types. One is nylon 6, nylon 66, nylon 610, nylon 11, nylon 1
The other type is called copolymer nylon, which is a copolymerization of 2, etc., and the other type is called modified nylon, which is a chemically modified nylon such as N-alkoxymethyl-modified nylon and N-alkoxyethyl-modified nylon. be. Among these alcohol-soluble nylon resins used in the present invention, copolymer nylon is more preferable.

[0012] These alcohol-soluble nylon resins are only soluble in lower aliphatic alcohols such as methanol and ethanol. It is sufficient to use something other than alcohol, which increases the range of solvent selection. If a charge generation layer is coated using a solvent that dissolves the undercoat layer, it may mix with the undercoat layer and deteriorate its characteristics, or depending on the coating method, problems such as uneven coating may occur. . As the coating solvent for forming the undercoat layer, the above-mentioned lower aliphatic alcohol is mainly used, but a mixed solvent containing water, benzyl alcohol, n-propyl alcohol, iso-propyl alcohol, etc. is also used. Good too. In addition, the thickness of the undercoat layer is 0.05~
50μ is appropriate.

[0013] Aluminate has the general formula xMI2O.
It is a compound defined by yAl2O3.zH2O, and specific examples include sodium aluminate, potassium aluminate, and magnesium aluminate. The reason why the repeatability of the photoreceptor under low humidity is improved by adding these compounds to the undercoat layer mainly composed of alcohol-soluble nylon resin is not yet clear, but it is probably due to the moisture absorption of these substances. It seems that the water content in the membrane is controlled depending on the performance. The amount added to the undercoat layer is desirably in the range of 0.1 to 200 parts by weight, preferably 0.5 to 100 parts by weight, per 100 parts by weight of the alcohol-soluble nylon resin.

As the conductive support on which the photoreceptor is formed, any of those employed in well-known electrophotographic photoreceptors can be used. Specific examples include metal drums or sheets made of aluminum, copper, etc., or laminates and vapor deposits of these metal foils. Further examples include plastic films, plastic drums, paper, etc., which are coated with a conductive substance such as metal powder, carbon black, copper iodide, or polymer electrolyte together with a suitable binder and subjected to conductive treatment. Other examples include plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are made conductive.

The charge generating layer can be provided by dispersing and coating a pigment or dye, preferably together with a binder, in a solvent. Pigments that can be used include azo pigments such as monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene pigments, and thiazole azo pigments; perylene pigments such as perylene acid anhydride and perylene acid imide. Anthraquinone or polycyclic quinone pigments such as anthraquinone derivatives, anthanithrone derivatives, dibenzpyrenequinone derivatives, pyrantrone derivatives, violanthrone derivatives and isoviolanthrone derivatives; metal phthalocyanines, metal naphthalocyanines, Examples include phthalocyanine pigments such as metal phthalocyanine and metal-free naphthalocyanine. Dyes that can be used include triphenylmethane dyes such as methyl violet, quinone dyes such as quinizarin, pyrium salts,
Examples include thiapyrylium salt and benzopyrylium salt.

Binders used in the charge generation layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic esters, and methacrylic esters, phenoxy resins, polysulfones, arylate resins, polycarbonates, polyesters, and cellulose. Examples include various polymers such as esters, cellulose ethers, urethane resins, epoxy resins, and acrylic polyol resins.

The binder is used in an amount of 1 to 1000 parts by weight, preferably 1 to 400 parts by weight, based on 100 parts by weight of the charge generating material. The thickness of the charge generation layer is 0.1
to 20 μm is preferable.

As charge transfer substances used in the charge transfer layer, triphenylamine derivatives represented by chemical formulas 1 to 5,

[0019]

[Chemical formula 1]

[0020]

[Case 2]

[0021]

[Chemical formula 3]

[0022]

[C4]

[0023]

[C5]

Stilbene derivatives represented by chemical formulas 6 to 14,

[0025]

[C6]

[0026]

[C7]

[0027]

[Chemical formula 8]

[0028]

[Chemical formula 9]

[0029]

[Chemical formula 10]

[0030]

[Chemical formula 11]

[0031]

[Chemical formula 12]

[0032]

[Chemical formula 13]

[0033]

[Chemical formula 14]

Butadiene derivatives represented by chemical formulas 15 and 16,

[0035]

[Chemical formula 15]

[0036]

[Chemical formula 16]

Examples include, but are not limited to, hydrazone derivatives represented by Chemical Formulas 17 to 25.

[0038]

[Chemical formula 17]

[0039]

[Chemical formula 18]

[0040]

[Chemical formula 19]

[0041]

[C20]

[0042]

[C21]

[0043]

[C22]

[0044]

[C23]

[0045]

[C24]

[0046]

[C25]

Binder resins used in the heavy transfer layer include polystyrene, acrylic resins typified by polymethyl methacrylate, polycarbonates having bisphenol A and Z skeletons, polyarylates, polyphenylene ethers, polyether sulfones, polyamides, polyimides, etc. can be used.

In the charge transfer layer, the binder is used in an amount of 10 to 400 parts by weight per 100 parts by weight of the charge transfer substance. The thickness of the charge transport layer is preferably 5 to 100 μm.

In the electrophotographic photoreceptor of the present invention, various antioxidants may be added to prevent deterioration due to oxidation of organic compounds of the constituent materials, and film formability, flexibility, and mechanical strength may be improved. Known plasticizers may be used for enhancement.

Furthermore, in the electrophotographic photoreceptor of the present invention, the pigment is dispersed in a solvent, and the dye, binder, and charge transfer agent are dissolved. The solvents used are chloroform, dichloroethane, trichloroethane, halogenated hydrocarbons such as trichloroethylene, benzene, toluene,
Aromatic hydrocarbons such as xylene, ethers such as dioxane, tetrahydrofuran, dimethoxyethane, cellosolves such as methyl cellosolve, dimethyl cellosolve, methyl cellosolve acetate, etc. alone or in combination of two or more solvents, or alcohol as necessary. A solvent such as acetonitrile, N,N-dimethylformamide, methyl ethyl ketone, etc. can be further added and used. Further, when coating a drum, a dip coating method or the like is used.

[0051]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Alcohol-soluble nylon resin (CM-8000, nylon 6/66/610/12 copolymer, manufactured by Toray Industries, Inc.)
A solution prepared by dissolving 1 part by weight in 20 parts by weight of methanol and adding 0.05 parts by weight of sodium aluminate (manufactured by Wako Pure Chemical Industries, Ltd. M) was applied onto a thin metal aluminum plate (JIS standard #1050). Apply with a tap, and
It was dried at 0 degrees for 30 minutes to form an undercoat layer with a thickness of about 0.5 μm.

[0053]

[C26]

Next, bisazo pigment 1 of exemplified compound 26
Weight parts and phenoxy resin (PKH manufactured by Union Carbide)
1 part by weight of J) was mixed with 100 parts by weight of dimethoxyethane and dispersed together with glass beads in a paint conditioner for 2 hours. The pigment dispersion thus obtained was applied onto the undercoat layer using an applicator and dried at 80 degrees for 15 minutes to form a charge generation layer having a thickness of about 0.2 μm.

Next, 10 parts by weight of the hydrazone compound shown in Exemplified Compound 17 and 10 parts by weight of polyarylate resin (U-polymer manufactured by Unitika) were dissolved in 200 parts by weight of dichloroethane, and the mixture was applied onto the film of the carrier-generating substance. Then, apply this solution with an applicator to a dry film thickness of 2
A charge transfer layer of 0 μm was formed.

After storing the laminated electrophotographic photoreceptor thus prepared in the dark at room temperature for a day and night, it was placed in an electrostatic recording tester "S".
P-428" (manufactured by Kawaguchi Electric Seisakusho Co., Ltd.), the photoreceptor is charged with a charging voltage of -4.8 kV, and then 2lux tungsten light is irradiated to reduce the photoreceptor's half-exposure amount E1/
2 was measured. Separately, using a drum photoconductor evaluation device (Cynthia 30 manufactured by Gentech), the photoconductor was charged and neutralized 1000 times at a room temperature of 23°C and a relative humidity of 55%. Potential and residual potential were measured. Further, similar repeated tests were conducted under the conditions of room temperature, 5° C., and relative humidity of 30%. The results are given in Tables 2 and 3.

Examples 2 to 4 Photoreceptors were prepared in the same manner as in Example 1, except that the amount of sodium aluminate added was as shown in Table 1 based on 100 parts by weight of alcohol-soluble nylon resin. The test was conducted in the same manner. The results are given in Tables 2 and 3.

[0058]

[Table 1]

Example 5 Alcohol-soluble nylon resin was mixed with Diamide 1874.
(Copolymer nylon mainly composed of nylon 12, manufactured by Daicel Corporation) A photoreceptor was prepared in the same manner as in Example 3, and the test was conducted in the same manner as in Example 3. The results are given in Tables 2 and 3.

Comparative Example 1 A photoreceptor was prepared in exactly the same manner as in Example 1, except that the undercoat layer was omitted, and tests were conducted in the same manner as in Example 1. Table 2 shows the results.
and given in Table 3.

Comparative Example 2 A photoreceptor was prepared in exactly the same manner as in Example 1, except that sodium aluminate was not added, and tests were conducted in the same manner as in Example 1. The results are given in Tables 2 and 3.

Example 6

[0063]

[C27]

A subbing layer was formed in the same manner as in Example 3, and 1 part by weight of the bisazo pigment of Exemplified Compound 27 and 1 part by weight of butyral resin (#3000-K manufactured by Denki Kagaku Co., Ltd.) and 100 parts by weight of tetrahydrofuran were added thereon. The resulting pigment dispersion was mixed with glass beads using a paint conditioner for 2 hours, and the obtained pigment dispersion was applied with an applicator and dried at 80 degrees for 15 minutes to form a charge generation layer with a thickness of about 0.2 μm.

Next, 10 parts by weight of the hydrazone compound shown in Exemplified Compound 19 and 10 parts by weight of polycarbonate resin (Z-200 manufactured by Mitsubishi Gas Chemical) were added to 16 parts by weight of dichloroethane.
This solution was applied onto the film of the carrier generating substance using an applicator to form a charge transfer layer having a dry thickness of 20 μm. The photoreceptor thus prepared was subjected to repeated tests similar to those in Example 1. The results are shown in Tables 2 and 3.

[0066]

[Table 2] Half-decreased exposure amount of photoreceptor and repetition characteristics under conditions of room temperature, 23°C, and relative humidity of 55% (charged potential and residual potential are both in volts)

0
067]

[Table 3] Repeatability characteristics under conditions of room temperature 5°C and relative humidity 30% (Charged potential and residual potential are both in volts.)

As is clear from the above, according to the present invention, it is possible to provide an electrophotographic photoreceptor that is highly sensitive and has excellent repeatability even under low temperature and low humidity conditions.

Claims (1)

[Claims] Claims: 1. An electrophotographic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transfer layer are sequentially laminated on a conductive support,
An electrophotographic photoreceptor characterized in that the undercoat layer is mainly composed of an alcohol-soluble nylon resin and contains an aluminate.