JPH0462560A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body which is excellent in both quality and productivity by providing a photosensitive layer contg. a perylene pigment of pH ranging 6.3 to 7.7 as a charge generating material on a conductive base body. CONSTITUTION:The perylene pigment of the pH ranging 6.3 to 7.7 is incorporated as a charge generating material into the photosensitive layer. The photosensitive layer includes a single layer type formed by mixing the charge generating material, a charge transfer material and a binder resin and a laminated type formed by laminating a charge generating layer and a charge transfer layer. The single layer contg. the perylene pigment of the pH ranging 6.3 to 7.7, the charge transfer material, the binder resin, etc., is formed on a conductive base body in order to obtain the electrophotographic sensitive body of the single layer type. The charge generating layer contg. the perylene pigment of the pH ranging 6.3 to 7.7 is formed on the conductive base body and the charge transfer layer contg. the charge transfer material is formed on this charge generating layer in order to obtain the electrophotographic sensitive body of the laminated type. The sequence of lamination is otherwise reversed to form the charge generating layer on the charge transfer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor with stable quality.

(Prior Art and Problems to be Solved by the Invention) A photoreceptor is manufactured by applying a coating liquid containing a mixture of a binder resin, a charge generating material, a charge transporting material, a solvent, etc. onto the surface of a conductive substrate and drying it. It is created by

For example, a perylene pigment is used as the charge generating material contained in the coating liquid. This perylene pigment is usually obtained by reacting perylenetetracarboxylic anhydride and quinlysine. Synthesized pigments contain residual impurities such as the starting material xylidine and the catalyst, and these act as a trap for the bok yaria generated in the photosensitive layer and degrade the properties of the photoreceptor, so they are usually purified. used.

As a method for purifying pigments, there are generally the following methods.

■A method of purifying pigments after synthesis by sublimation.

■A method in which the pigment after synthesis is washed with an aqueous sulfuric acid solution and then with water.

■A method in which the synthesized pigment is washed with an acid aqueous solution and an alkaline aqueous solution, and then with water.

■A method in which pigments are washed with a large amount of water after synthesis.

Although pure pigment can be obtained by the method (2) above, the production efficiency is low and it is disadvantageous for industrial production.

In method (2) above, if post-washing with sulfuric acid remaining in the pigment is insufficient, other materials (for example, binder resin) may be deteriorated, resulting in a decrease in aging characteristics.

In the methods of ■ and ■ above, amine compounds (such as bovine silydine)
If amine compounds remain in the pigment due to poor cleaning,
There is a drawback that the sensitivity of the photoreceptor produced is greatly reduced.

As described above, the properties of the above-mentioned perylene pigments vary greatly depending on the purification method, and this greatly affects the properties of photoreceptors, making it difficult to maintain quality in mass production of photoreceptors. In addition, as mentioned above, various methods have been used to purify pigments, and as the number of refining steps increases, impurities contained in pigments are removed.
It has been known that the properties of the photoreceptor produced can be improved, but it is not known how much purification is required. Therefore, there is room for improvement in terms of photoreceptor productivity since the purification process becomes more than necessary.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an electrophotographic photoreceptor that is excellent in both quality and productivity.

(Means and Effects for Solving the Problems) The electrophotographic photoreceptor of the present invention has a conductive substrate and a charge-generating material of p.
The present invention is characterized by providing a photosensitive layer containing a perylene pigment whose H is in the range of 6.3 to 7.7, thereby achieving the above object.

That is, the present inventors investigated in detail the relationship between various physical properties of perylene pigments as charge-generating materials and the characteristics of photoreceptors made using the same, and found that the pH of the pigments used and the characteristics of photoreceptors It has been found that there is a correlation between the physical properties of the photosensitive material and the physical properties of the photoreceptor, and that a photoreceptor with stable quality can be obtained by using a pigment having a pH of 6.3 to 7.7.

(Preferred Embodiment) The electrophotographic photoreceptor of the present invention contains a perylene pigment having a pH in the range of 6.3 to 7.7 in the photosensitive layer as a charge generating material.

The above-mentioned photosensitive layer includes a single layer type in which a charge generation material, a charge transport material and a binder resin are mixed, and a multilayer type in which a charge generation layer and a charge transport layer are laminated. It is applicable to both.

To obtain a single-layer electrophotographic photoreceptor, p
A single layer containing a perylene pigment with H in the range of 6.3 to 7.7, a charge transport material, a binder resin, etc. may be formed. To obtain a laminated electrophotographic photoreceptor, a charge generation layer containing a perylene pigment having a pF+ of 6.3 to 7.7 is formed on a conductive substrate, and a charge transport layer is formed on this charge generation layer. A charge transport layer containing the material may be formed. Also,
The stacking order may be reversed, and the charge generation layer may be formed on the charge transport layer.

As the charge transport material, conventionally used charge transport materials can be used, such as oxadiazoles such as 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole. styryl compounds such as 9-(4-diethylaminostyryl)anthracene,
Carbazole compounds such as polyvinyl carbazole, 1
- Pyrazoline compounds such as phenyl-3-(P-dimethylaminophenyl) pyrazole, hydrazone compounds,
Nitrogen-containing cyclic compounds and fused polycyclic compounds such as triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds Examples include compounds.

These charge transport materials may be used alone or in combination of two or more. Note that a binder resin is not necessarily required when a charge transporting material having film-forming properties such as polyvinylcarbazole is used.

Various resins can be used as the binder resin,
For example, styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic polymers, styrene-
Acrylic copolymer, ethylene-vinyl acetate copolymer,
Polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, acrylic modified urethane resin, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin , polyether resin, phenol resin, and various other polymers are exemplified. Furthermore, photocurable resins such as epoxy acrylate can also be used. Furthermore,
Photoconductive polymers such as poly-N-vinylcarbazole may also be used as binder resins.

As the charge generating material, one represented by the following formula (I) is used.

(In the formula, R represents an alkyl group or an aryl group.) Perylene pigments are usually obtained by reacting perylenetetracarboxylic anhydride with a compound having an amine group. Since it contains a reactant amine compound (for example, 3,5-bovine silidine, etc.) and a catalyst (for example, zinc chloride, etc.), it is purified according to a conventionally known method.

Examples of this purification method include water washing, acid washing, and alkali washing using a washing liquid such as water, acid aqueous solution, alkaline aqueous solution, etc., and a plurality of these types of washing may be used in combination. In particular, a method in which acid washing and alkaline washing are used together and washing with condensed water is preferably used.Acid washing can neutralize amine compounds such as xylidine that remain in the pigment, and alkaline washing can neutralize amine compounds such as xylidine. Zinc etc. can be decomposed and removed.

In the present invention, the pH after washing with the washing liquid is 6.
A pigment having a particle size ranging from 3 to 7.7 is used.

If a pigment with a pH of less than 6.3 is used, it will adversely affect other materials such as the binder resin and deteriorate the aging characteristics of the photoreceptor produced. Furthermore, if a pigment with a pH exceeding 7.7 is used, residual alkali components (such as xylidine, etc.) in the pigment trap carriers generated in the photosensitive layer, reducing the sensitivity of the photoreceptor. It is something.

By preparing a coating liquid using a pigment having a pH within such a range, applying the coating liquid and drying it to form a photosensitive layer, a photoreceptor with excellent quality can be produced. Therefore, it is only necessary to set the degree of purification so that the pH of the pigment used falls within the above range, so the purification process does not become more than necessary, and the time and labor required for the purification are not spent more than necessary. It disappears.

In addition to using perylene pigment having a pH in the range of 6.3 to 77 alone as the charge generating material, it can also be used in combination with other charge generating materials. Examples of other charge-generating materials include selenium, selenium-tellurium, amorphous silicon, pyrylium salts, anthanthrone pigments, phthalocyanine pigments, indigo pigments, triphenylmethane pigments, threne pigments, toluidine pigments,
Examples include pyrazoline pigments, azo pigments, and quinacridone pigments.

Furthermore, a surfactant, a leveling agent, etc. may be used to improve the dispersibility, coating properties, etc. of the charge transporting material and the charge generating material.

In addition, as a solvent for dissolving the charge generating material, charge transporting material, binder resin, etc. to form a coating solution, for example,
Alcohols such as methanol, ethanol, isoprohanol, and phthanol, aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, benzene, toluene,
Aromatic hydrocarbons such as xylene, 10-genated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, dimethyl ether, diethyl ether,
Examples include ethers such as tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethyl formaldehyde, dimethyl formamide, and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

In addition, examples of the conductive substrate include aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium,
Examples include simple metals such as cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, plastic materials on which the above metals are vapor-deposited or laminated, and glass coated with aluminum iodide, tin oxide, indium oxide, etc. Ru.

The conductive substrate may be in the form of a sheet or a drum, and it is sufficient that either the substrate itself has conductivity or the surface of the substrate has conductivity.

The substrate preferably has sufficient mechanical strength during use.

In the laminated electrophotographic photoreceptor, the charge generation material and the binder resin constituting the charge generation layer can be used in various ratios, but with respect to 100 parts (parts by weight, same hereinafter) of the binder resin, 5 to 500 parts of charge generating material, especially 10 to 25 parts
Preferably, it is used in a proportion of 0 parts.

Further, the charge generation layer may have an appropriate thickness, but it is preferably formed to have a thickness of about 0.01 to 5 .mu.m, particularly 0.1 to 3 .mu.m.

The charge transport material and the binder resin constituting the charge transport layer can be used in various ratios, so that charges generated in the charge transport layer by light irradiation can be easily transported.
10 to 500 parts of charge transport material per 100 parts of binder resin
Parts, particularly preferably 25 to 200 parts.

In addition, the charge transport layer has a thickness of 2 to 100μ11, especially 5 to 3
Preferably, the thickness is about 0 μm.

In a single-layer type electrophotographic photoreceptor, the charge generating material is 2 to 20 parts, especially 3 to 15 parts, and the charge transporting material is 40 to 200 parts, especially 50 to 100 parts, based on 100 parts of the binder resin.
It is appropriate that the The thickness of the single-layer type photosensitive layer is preferably about 10 to 50 .mu.m, particularly about 15 to 25 .mu.m.

When a photosensitive layer including a charge generation layer and a charge transport layer is formed by a coating method, the charge generation material or the charge transport material and the binder resin are coated using a conventionally known method such as a roll mill, a ball mill, an attritor, or a paint shaker. , prepare a coating solution using an ultrasonic disperser or the like.

(Example) Hereinafter, the present invention will be explained in more detail based on examples.

Note that the pH was measured in accordance with JIS K, 5101.

Point 11 Pull 1 <Preparation of electrophotographic photoreceptor> Perylene pigment was synthesized by reacting perylenetetracarboxylic anhydride and xylidine.

Next, 100 parts by weight of this perylene pigment was dissolved in 1000 parts by weight of concentrated sulfuric acid, and then this was added dropwise to a large amount of cold water to cause reprecipitation. Separate this by filtration and add 0.1N NaOH
It was placed in an aqueous solution SOO parts by weight and subjected to ultrasonic dispersion for 2 minutes. This was further filtered, placed in a 0.1 N hydrochloric acid aqueous solution, and subjected to ultrasonic dispersion for 2 minutes.

Thereafter, it was washed with 1000 parts by weight of distilled water. By repeating the above operation three times, a perylene pigment with a pH of 6.4 was obtained.

1 part by weight of the obtained perylene pigment (charge generating material) and 40 parts by weight of tetrahydrofuran were mixed using an ultrasonic disperser.
After stirring and mixing for a minute, 10% of polyvinylcarbazole (Tupicol 210, manufactured by Anan Perfume Co., Ltd.) was added as a charge transport material.
% tetrahydrofuran solution and secondary dispersion was carried out for 2 minutes using an ultrasonic dispersion machine to prepare a coating solution for a single-layer type photosensitive layer.

Apply this coating solution onto the aluminum foil with a wire bar (#28
) and then dried with hot air at 100° C. for 1 hour to form a single-layer photosensitive layer with a thickness of about 10 μm, thereby producing an electrophotographic photoreceptor.

<Evaluation of electrophotographic photoreceptor> Electrostatic copying test device (manufactured by Kawaguchi Electric Co., Ltd., Model-810)
The electrophotographic photoreceptor was positively charged with an applied voltage of +5.5 Kv using 0), and the electrophotographic characteristics were measured under the following conditions. The results are shown in Table 1.

Exposure time = 10 seconds Irradiation light: White light Light intensity: 10 Lux Dark decay after charging = 2 seconds In the table, Vl (V) is the photoreceptor when the voltage is applied under the above conditions and the photoreceptor is charged. In addition, E+ 1/2 (Lux-sec) is the half reduction calculated from the exposure time required for the surface potential to become 1/2 of the initial surface potential Vl (V). Indicates the amount of exposure. Further, V lr, p, (V) in the table is the surface potential measured 5 seconds after the start of exposure as a residual potential. In addition, the values in the lower row of the table indicate the characteristics after repeated copying 500 times.

A perylene pigment was synthesized in the same manner as in Example 1 above. Next, 100 parts by weight of this perylene pigment was placed in 500 parts by weight of a 0.1N hydrochloric acid aqueous solution, and ultrasonic dispersion was performed for 2 minutes. This was separated by filtration and 0.1 N NaOH aqueous solution 500
It was placed in a weight part and subjected to ultrasonic dispersion for 2 minutes. By repeating the above operation three times, a perylene pigment with a pH of 6.8 was obtained.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of 10 μm was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. Ta.

Sotachioka Lord A perylene pigment was synthesized in the same manner as in Example 1.

Next, 100 parts by weight of this perylene pigment was placed in parts by weight of a 0.1N hydrochloric acid aqueous solution SOO, and ultrasonic dispersion was performed for 2 minutes. Thereafter, the pH was adjusted to 7 by washing with 1000 parts by weight of acetone and then 3 times with 1000 parts by weight of distilled water.
, 5 perylene pigments were obtained.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of 10 μm was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. Ta.

A perylene pigment was synthesized in the same manner as in Example 1 above. Next, 100 parts by weight of this perylene pigment was dissolved in 1000 parts by weight of concentrated sulfuric acid, and then this was added dropwise to a large amount of cold water to cause reprecipitation. This was filtered and washed with 1000 parts by weight of distilled water. By repeating the above operation three times, a perylene pigment with a pH of 5.7 was obtained.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of about 10 μm was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. Ta.

A perylene pigment was synthesized in the same manner as in Example 1 above. Next, 100 parts by weight of this perylene pigment was dissolved in 1000 parts by weight of concentrated sulfuric acid, and then this was added dropwise to a large amount of cold water to cause reprecipitation. This was filtered and washed with 500 parts by weight of 0.1N NaOH aqueous solution. After that, distilled water 1000
Washed with parts by weight. By repeating the above operation three times, the pH
A 6,0 perylene pigment was obtained.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of 10 μm was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. .

Master of the Saikyo Hill A perylene pigment was synthesized in the same manner as in Example 1.

Next, 100 parts by weight of this perylene pigment was washed with 500 parts by weight of 0.1N hydrochloric acid aqueous solution, and then washed with 100 parts by weight of acetone.
A perylene pigment having a pH of 7.9 was obtained by washing with 1 part by weight and then 3 times with 1000 parts by weight of distilled water.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of 10μ was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. Ta.

salt mosquito goto A perylene pigment was synthesized in the same manner as in Example 1.

Next, 100 parts by weight of this perylene pigment was added to 100 parts by weight of acetone.
After washing with 0 parts by weight, a perylene pigment of pl(8,3) was obtained by washing three times with 1000 parts by weight of distilled water.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of 10 μm was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. .

Hidden Δ Takumi A perylene pigment was synthesized in the same manner as in Example 1.

Next, 100 parts by weight of this perylene pigment was added to 1000 parts by weight of distilled water.
A perylene pigment having a pH of 9.2 was obtained by washing three times with parts by weight.

Using the obtained perylene pigment, an electrophotographic photoreceptor having a single layer photosensitive layer with a film thickness of 10 μm was prepared in the same manner as in Example 1, and its electrophotographic properties were measured. The results are shown in Table 1. .

(Hereinafter referred to as blank space) It is possible to provide an electrophotographic photoreceptor that is extremely suitable for industrial production.

that's all

Claims (1)

[Claims] 1. On a conductive substrate, a charge generating material with a pH of 6.3
An electrophotographic photoreceptor comprising a photosensitive layer containing a perylene pigment in the range of 7.7 to 7.7.