JPH04350662A - Electrophotographic sensitive body and production thereof - Google Patents

Abstract

PURPOSE:To improve the dispersibility, coatability and adhesiveness of a charge generating material and charge transfer performance by incorporating a specific phenoxy bromide resin at >=5wt.% and <=90wt.% into a binder resin. CONSTITUTION:This photosensitive body has a photosensitive layer contg. a charge generating layer and a charge transfer on a conductive base body and is constituted by incorporating an org. pigment as the charge generating material and a binder resin as the binder into the charge generating layer. This binder resin contains the phenoxy bromide resin expressed by formula I within the range of >=5wt.% and <=90wt.%. Namely, this photosensitive body is adequately produced by dispersing the org. pigment into a soln. dissolved with only the phenoxy bromide resin, mixing and dispersing this dispersion with and into a soln. dissolved with the binder resin of the remaining part exclusive of the phenoxy bromide resin, applying such soln. on the conductive base body to form the charge generating layer, and providing the charge transfer layer thereon.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer including a charge generation layer and a charge transport layer on a conductive substrate, and a method for manufacturing the same.

0002

2. Description of the Related Art Electrophotographic photoreceptors (hereinafter simply referred to as photoreceptors) generally include a photosensitive layer containing a photoconductive substance on a conductive substrate. In the electrophotographic image formation invented by Carlson, the surface of the photoreceptor is charged, imagewise exposed to form an electrostatic latent image, and the electrostatic latent image is developed with toner to form a visible image. Then, the visible image is transferred and fixed onto a support such as paper. On the other hand, the surface of the photoreceptor is cleaned by removing residual toner and eliminating static electricity, and is used repeatedly over a long period of time. Therefore, as a photoreceptor, it not only has good electrophotographic properties such as charging properties, charge retention properties, and photosensitivity properties, but also stability of electrophotographic properties during repeated use over a long period of time, abrasion resistance,
It is required to have good durability such as ozone resistance and light resistance to ultraviolet rays, and furthermore, it is required to have little variation in characteristics depending on the environment during use (low temperature/low humidity, high temperature/high humidity).

Conventionally, inorganic photoreceptors containing as a main component an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide have been widely used. However, these inorganic photoreceptors have various drawbacks such as photosensitivity, thermal stability, durability, environmental resistance, and toxicity, and are not always fully satisfactory.

In contrast to these inorganic photoreceptors, photoreceptors using organic photoconductive substances have been actively researched and developed in recent years.

[0005] Compared to inorganic photoreceptors, these organic photoreceptors have
Generally, it is attracting attention and being put into practical use because of its low toxicity, light weight, flexibility, and excellent productivity. For example, Japanese Patent Publication No. 50-10496 proposes a photoreceptor containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone, and Japanese Patent Publication No. 48-25658 proposes a photoreceptor containing poly-N- - A photoreceptor in which vinyl carbazole is sensitized with pyrylium dye has been proposed. However, these photoreceptors were not necessarily fully satisfactory in terms of photosensitivity and durability. Later, a so-called functionally separated photoreceptor was proposed, in which the photoreceptor layer was functionally separated into a layer that generates charges and a layer that moves the generated charges when exposed to light in the presence of an electric field, and the performance of organic photoreceptors improved. It has improved dramatically. For example, Japanese Patent Publication No. 55-42380 proposes a functionally separated photoreceptor using chlorodiane blue and a hydrazone compound.

In this way, by separating the photosensitive layer into a charge generation layer and a charge transport layer and assigning their functions, it is possible to easily produce photoreceptors with various characteristics, such as high photosensitivity and durability. It is expected that a photoreceptor with excellent properties will be obtained.

[0007] The charge generation layer of such a photoreceptor generally consists of:
It is composed of an organic pigment as a charge generating substance and a binder resin as a binder. This is because if the charge generation layer is made of only organic pigments, it itself has no film-forming ability, resulting in poor adhesion to the substrate and charge transport layer, resulting in insufficient mechanical strength of the photoreceptor. This is because such problems tend to occur, and the dispersibility and dispersion stability of the coating liquid are insufficient, resulting in the problem that continuous coating cannot be performed industrially.

The required properties for the binder resin used in the charge generation layer are: (1) good dispersibility of the organic pigment as the charge generation substance;
Good dispersion stability. (2) Good adhesion to the conductive substrate or subbing layer and charge transport layer. (3) It should not be attacked by the charge transport layer coating solution or the intermediate layer coating solution. (4) Stable against changes in temperature and humidity and good light resistance. (5) The transport efficiency of charges generated by exposure to light is high. The binder resin has become a major factor influencing the performance of the charge generation layer and, ultimately, the performance of the photoreceptor.

However, there are no governing rules regarding the selection of binder resins, and the actual situation is that they are selected empirically depending on the type of organic pigment as a charge-generating substance and its film quality, which is still not fully satisfactory. I haven't gotten what I could have. An example of a binder resin used as such a binding agent is polyvinyl butyral resin (Japanese Patent Application Laid-Open No.
8-105154), acid value 10 to 40
, acrylic resin with a glass transition temperature of 70°C or less (Japanese Patent Application Laid-Open No.
8-192040), polyvinylpyrrolidone resin (disclosed in JP-A-56-12646), polyvinylpyridine resin (disclosed in JP-A-56-60443), phenol resin (disclosed in JP-A-58-17448) Various methods have been proposed, such as those disclosed in Japanese Patent Publication No.

[0010] In recent years, electrophotographic application devices such as copying machines and non-impact printers have become faster, and there has been a stronger demand for high-quality images to be stably obtained over a long period of time. For this reason, photoreceptors are required to have better electrophotographic properties, durability, and environmental resistance, and binder resins to be used in the charge generation layer are also being studied, as disclosed in Japanese Patent Application Laid-Open No. 2-135453. By using a brominated phenoxy resin represented by the following formula (1), it has excellent adhesion and electrophotographic properties such as chargeability, dark decay, and sensitivity, as well as excellent repeatability and moisture resistance. It is disclosed that a photoreceptor can be obtained.

[0011]

[Case 2]

[In formula (1), n represents a positive integer. ]

[
0013

[Problems to be Solved by the Invention] However, when a brominated phenoxy resin alone is used as a binder resin, there is a problem in that the organic pigment as a charge generating substance has poor dispersibility and it is difficult to prepare a coating liquid for the charge generating layer. Ta. That is, using only brominated phenoxy resin as a binder resin,
In order to disperse the organic pigment contained in this into fine particles of submicron size or less, using normal dispersion methods such as dispersion equipment such as a ball mill or sand mill requires a long dispersion time lasting from several days to several tens of days. Furthermore, if the obtained dispersion is left to stand, it will begin to aggregate within a few hours, and lump-like lumps will form in the coating solution.

The present invention solves the above-mentioned problems, and provides a charge generating material as a binder for a charge generating layer, which has good dispersibility and dispersion stability, and has excellent coating properties and adhesive properties. By finding a binder resin with good charge transport ability and using this binder resin to prepare a coating liquid for the charge generation layer and coating the charge generation layer, it is possible to achieve high sensitivity, excellent durability, and long-term repeated use. The object of the present invention is to provide a photoreceptor with stable characteristics and less fluctuation in characteristics due to changes in temperature and humidity.

[0015]

[Means for Solving the Problems] According to the present invention, in an electrophotographic photoreceptor comprising a photosensitive layer including a charge generation layer and a charge transport layer on a conductive substrate, the charge generation layer is A photosensitive material comprising an organic pigment as a charge generating substance and a binder resin as a binder, the binder resin containing 5% by weight or more and 90% by weight or less of a brominated phenoxy resin represented by the following formula (1). It is solved by becoming a body.

[0016]

[Chemical formula 3]

[In formula (1), n represents a positive integer. ]

[
The binder resin represented by the above formula (1) is a known compound, for example, Phenotote YP (trade name).
It is known as B-43C (manufactured by Toto Kasei Co., Ltd.). The resin of formula (1) used here preferably has a weight average molecular weight of 10,000 to 300,000, and particularly has a weight average molecular weight of 50,000 to 100,000 to improve the mechanical strength of the coating film. This is desirable from the viewpoint of workability during membrane production.

Examples of resins that can be used in the binder resin together with brominated phenoxy resins include double bonds such as styrene, vinyl acetate, acrylic esters, methacrylic esters, vinyl alcohol, ethyl vinyl ether, maleic esters, ethylene, propyrel, and butadiene. Polymers or copolymers of compounds having , phenoxy resins, polycarbonate resins, polysulfone resins, polyketone resins, polyester resins, polyvinyl acetal resins, polyamide resins, polyurethane resins, epoxy resins, phenol resins, melamine resins, urea resins, silicones Although various resins such as resin and cellulose resin are used, a particularly effective binder resin in this invention is polyvinyl acetal resin.

[0020] Polyvinyl acetal resins are known as, for example, polyvinyl butyral resin, polyvinyl acetoacetal resin, and polyvinyl formal resin. ) and Denka Formal (manufactured by Denki Kagaku Kogyo Co., Ltd.).

[0021] The binder resin of the present invention is obtained by adding the above-mentioned various resins to the brominated phenoxy resin alone or in combination. However, if the proportion of the brominated phenoxy resin to the entire binder resin exceeds 90% by weight, The dispersibility and dispersion stability of the coating liquid will deteriorate rapidly, and if it is less than 5% by weight, the sensitivity and charge retention will deteriorate, and the moisture resistance will also decrease, which is not preferable.

Organic pigments used in the charge generation layer include azo pigments, anthraquinone pigments, polycyclic quinone pigments,
Indigo pigments, diphenylmethane pigments, azine pigments, cyanine pigments, quinoline pigments, benzoquinone,
naphthoquinone pigments, naphthalucide pigments, perylene pigments, fluorenone pigments, squarylium pigments,
Azlenium pigments, perinone pigments, quinacridone pigments, phthalocyanine pigments, naphthalocyanine pigments, polyphylline pigments, etc. are used. Among these, in this invention, polycyclic quinone pigments, such as 3,9-dibromoanthanthrone, α, β, χ, ζ type metal-free phthalocyanine, copper phthalocyanine, vanadyl phthalocyanine, titanyl phthalocyanine, cytoxyphthalocyanine Metal phthalocyanines such as and azo pigments represented by the following general formula are effective.

[0023]

[C4]

[In the formula, R1 represents a halogen atom, an alkyl group, or an alkoxy group, R2 represents an alkyl group that may have a substituent, and R3 represents a hydrogen atom, a cyano group, or a carbamoyl group. , a carboxyl group, an ester group, or an acyl group, and R4 represents any one of a hydrogen atom, a halogen atom, a nitro group, an alkyl group, and an alkoxy group. ]

Specific examples of these azo pigments are as follows.

[0026]

[C5]

[0027]

[C6]

These pigments can be used alone or in any combination of pigments of any type in any proportion.

Further, as the organic solvent, cyclohexanone, dioxane, tetrahydrofuran, dimethylformamide, methyl ethyl ketone, ethyl acetate, cellosolve, toluene, xylene, methylene chloride, etc. are used.

The coating liquid for the charge generation layer is prepared by dissolving and dispersing a binder resin containing the above-mentioned brominated phenoxy resin, an organic pigment, and an organic solvent using a dispersion device such as a ball mill, sand mill, or attritor. A spreading agent, a surfactant, etc. may be added to the coating liquid as necessary. The mixing ratio of binder resin and organic pigment in the coating liquid is 5 parts by weight to 5 parts by weight of binder resin to 100 parts by weight of organic pigment.
200 parts by weight is desirable, more preferably 10 parts by weight -
It is 100 parts by weight. If the amount is less than 5 parts by weight, the adhesion of the charge generation layer will be poor, and if it is more than 200 parts by weight, the photosensitivity will tend to decrease.

In preparing the coating solution for the charge generation layer, first, the brominated phenoxy resin and the organic pigment are mixed together with an organic solvent such as hexanone or dioxane that dissolves the brominated phenoxy resin well until a predetermined pigment particle size is obtained. Then, by adding a solution of the remaining binder resin such as polyvinyl acetal to this dispersion and further mixing and dispersing, a coating liquid in which the organic pigment is well dispersed and has good dispersion stability is obtained. This is preferable because the effects of this invention become more pronounced.

The charge generation layer is formed by applying such a coating liquid onto a conductive substrate by a known method, drying it, and then curing it by heating if necessary. The thickness of the charge generation layer is 0.05μ
m to 5 μm is desirable. If the thickness is less than 0.05 μm, film forming properties are poor and defects are likely to occur in the image, and if it is more than 5 μm, the photoreceptor characteristics such as charging characteristics deteriorate.

The conductive substrate has the purpose of supporting each layer as well as functioning as an electrode, and may have any shape such as cylindrical, plate, or film, and may be made of aluminum, aluminum alloy, stainless steel, or conductive. Polymer plastics, etc. are used. If necessary, a conductive coating can be applied to the conductive substrate in order to improve the surface smoothness.

A coating liquid in which an organic compound as a charge transport substance and a binder resin as a binder are dispersed and dissolved in an organic solvent is applied onto this charge generation layer by a known method and dried to form a charge transport layer. It is formed into a photoreceptor.

Materials suitable as charge transport substances include:
Polymer compounds such as poly(N-vinylcarbazole), poly(vinylanthracene), poly(9,10-anthracenylendodecanedicarboxylate), polysilane, polygermane, poly(p-phenylene sulfide), hydrazone type There are low-molecular-weight compounds such as pyrazoline compounds, enamine compounds, styryl compounds, arylmethane compounds, arylamine compounds, butadiene compounds, and azine compounds, and these can be used alone or in combination.

Binder resins used when a low molecular weight compound is used as a charge transport material include polycarbonate, polyester, polyurethane, epoxy resin, silicone resin, styrene resin, etc., and these may be used alone or in combination. . At this time, 50 parts by weight of the binder resin to 100 parts by weight of the low molecular compound
A mixture of 200 parts by weight of a low molecular compound,
Preferably, the binder resin is dissolved in a solvent that dissolves the binder resin as well.

[0037] If necessary, stabilizers such as antioxidants, ultraviolet absorbers, and proton absorbers can be added to the coating liquid for the charge transport layer. A spreading agent, anti-sagging agent, etc. can also be added to prevent sagging.

The thickness of the charge transport layer is arbitrarily determined depending on the charging characteristics, photosensitivity, printing durability, etc. required for the photoreceptor, but is usually 5 μm to 50 μm, preferably 10 μm to 3 μm.
It is assumed to be 0 μm.

[0039]

[Function] When the brominated phenoxy resin represented by formula (1) is used alone as the binder resin for the charge generation layer of a functionally separated photoreceptor, the sensitivity improves, but the dispersion of the coating liquid for the charge generation layer properties and dispersion stability deteriorate. As a result of intensive research in order to solve this problem, we found that by mixing appropriate amounts of the brominated phenoxy resin represented by formula (1) and other binder resins as the binder resin, we improved the dispersibility of the coating liquid. It was found that deterioration of dispersion stability can be prevented.

FIG. 1 shows the brominated phenoxy resin in the binder resin when the binder resin as a binder of the charge generation layer of a functionally separated photoreceptor contains the brominated phenoxy resin represented by formula (1). FIG. 2 is a diagram showing the relationship between the content of and the dispersion stability of a coating liquid for a charge generation layer and the sensitivity of a photoreceptor. Dispersion stability was evaluated based on the number of days during which the dispersion state was maintained well after preparing the coating liquid for the charge generation layer. As seen in Figure 1, the content of brominated phenoxy resin is 90% by weight.
If it exceeds this value, the dispersion stability deteriorates rapidly, and the sensitivity decreases as the content of the brominated phenoxy resin decreases. The content of brominated phenoxy resin is 5% by weight.
When the content is within the above range of 90% by weight or less, a coating liquid for a charge generation layer can be obtained which has good dispersion stability, good coating properties and adhesion properties, and can form a highly sensitive photosensitive layer. I understand.

The remaining binder resin used together with the brominated phenoxy resin is particularly preferably one containing a polyvinyl acetal resin.

[0042] By forming the charge generation layer with a coating liquid for the charge generation layer using the binder resin having the composition as described above, it has high sensitivity, excellent durability, and stable characteristics for long-term repeated use. In addition, it is possible to obtain a photoreceptor with less variation in characteristics due to changes in temperature and humidity.

Furthermore, it is not necessary to provide a special undercoating layer on the surface of the conductive substrate on which the charge generation layer is formed, or to perform alumite treatment on the surface when aluminum or aluminum alloy is used as the conductive substrate. It was also found that photoreceptors capable of producing high-quality images under various environments can be produced.

[0044]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited thereto.

(1) Coating liquid for charge generation layer As shown in Table 1, 70 parts by weight of various charge generation substances and 30 parts by weight of binder resins of various compositions are combined and dissolved and dispersed in an organic solvent to form a charge. Coating liquid N for generation layer
o. 1~No. Prepare 16. The preparation method is as follows: First, 70 parts by weight of the charge generating substance and a predetermined amount of the brominated phenoxy resin shown in formula (1) above are mixed with 100 parts by weight of cyclohexanone as an organic solvent, and the mixture is ground in a sand mill for 36 hours to dissolve. - A dispersion liquid was prepared by dispersion, and a predetermined amount of the remaining resin and 3900 parts by weight of tetrahydrofuran were added to this dispersion liquid, and the mixture was dissolved and dispersed in a paint shaker for 10 hours to obtain a coating liquid.

[0046]

[Table 1]

These coating solutions were examined for changes in particle size due to aggregation of the organic pigment, which is a charge-generating substance, when the coating solutions were left at room temperature after preparation. The results are shown in Table 2.

[0048]

[Table 2]

As seen in Table 2, by including a polyvinyl acetal resin in the binder resin, the dispersibility and dispersion stability of the organic pigment as a charge generating substance are improved. It has been found that it is preferable to include 5% by weight or more of polyvinyl acetal resin. This effect hardly changes even if the type of polyvinyl acetal resin changes. It can also be seen that almost the same effect can be obtained even if the type of organic pigment is changed.

(2) Coating liquid for charge transport layer As the charge transport material, the following compound No. II-1, No.
．． II-2, No. II-3, No. II-4 was used.

[0051]

[C7]

Compound No. 1 is used as a charge transport substance. II-1
, No. II-2 and No. When II-3 is used, 100 parts by weight of a charge transport substance and 100 parts by weight of a polycarbonate resin (Panlite L-1225; manufactured by Teijin Kasei Ltd.) as a binder resin are mixed with 60 parts by weight of dichloromethane.
It was dissolved in 0 parts by weight to prepare a coating liquid. In addition, polymeric compound No. When using II-4, the compound is added to toluene at a concentration of 15% by weight without using a binder resin.
It was dissolved to give a coating liquid.

[0053] Soluble nylon CM-4001 (manufactured by Toray Industries, Inc.) is placed on a conductive substrate made of an aluminum alloy cylinder (external diameter 60 mm and 80 mm) that has been subjected to the required machining and surface treatment, or on this conductive substrate. On a subbing layer having a thickness of 1 μm formed by dip-coating a solution prepared by dissolving 1.5% by weight in methanol, each of the above-mentioned charge generation layer coating liquids is dip-coated and dried. Film thickness 0.
A charge generation layer of 1 μm was formed. The various charge transport layer coating liquids described above were applied by dip coating onto these charge generation layers to a film thickness of 20 mm.
Photoreceptor No. 1, which has a charge transport layer of .mu.m in thickness and has a combination of a charge generation layer and a charge transport layer as shown in Table 3. 1~N
o. No. 19 was produced.

[0054]

[Table 3]

[0055] Regarding these photoreceptors, initial surface potentials Vo (volts),
Charge retention rate after 5 seconds (Surface potential after 5 seconds left in the dark is Vo
The value obtained by multiplying the value divided by 100) Vk5 (%) was measured. Next, we developed photoreceptor No. 1, which uses a phthalocyanine pigment as a charge-generating substance and is sensitive to long wavelength light.
．． 1~No. 9, the wavelength is 780 nm and the light intensity is 1.
Irradiation with monochromatic light of 0 μW/cm2 reduces the surface potential to 1/2
The half-reduced exposure energy E1 is determined by measuring the time it takes to decay to
/2 (μJ/cm2), and 5μJ/cm
2. The residual potential Vr (volts) after exposure was measured. Photoreceptor No. 1 uses 9,10-dibromanthanthrone as a charge generating substance. 10~No. 12, 9, 1
Compound No. 0-dibromanthanthrone and an azo compound. Photoconductor No. I-1 was mixed at a ratio of 9:1. 13. Compound No. which is an azo compound
．． Photoconductor No. I-1 is used. 14~No. For No. 19, irradiate white light of 2.1 lux and measure the time for the surface potential to decay to 1/2 to find the half-decreased exposure energy E1/2 (lux/sec), The residual potential Vr (volt) after exposure was measured.

The above measurements regarding the initial performance of the photoreceptor were
The tests were carried out under a low temperature and low humidity environment (temperature 10°C, relative humidity 40%), a normal temperature environment (temperature 22°C, relative humidity 60%), and a high temperature and high humidity environment (temperature 35°C, relative humidity 85%). The results were transferred to photoreceptor No. 1~No. For 9, see Table 4, Table 5,
Table 6 shows photoreceptor No. 10~No. Table 7 for 19
, Table 8 and Table 9.

[0057]

[Table 4]

[0058]

[Table 5]

[0059]

[Table 6]

[0060]

[Table 7]

[0061]

[Table 8]

[0062]

[Table 9]

From Tables 5 to 9 above, photoreceptor No. 7,
No. 8, No. It can be seen that No. 18 has poor sensitivity and a large residual position, and these characteristics are highly dependent on the environment. In all of these photoreceptors, the binder resin of the charge generation layer does not contain the brominated phenoxy resin of the formula (1), or contains only a small amount of the brominated phenoxy resin, and the binder resin of the charge generation layer contains 5 The effect of including more than % by weight of brominated phenoxy resin is obvious. In addition, photoreceptor No. 1 contains a large amount of brominated phenoxy resin in the binder resin of the charge generation layer. 9, No. No. 19 has good properties, but as shown in Table 2, there are problems with the dispersibility and dispersion stability of the coating liquid for the charge generation layer, making it difficult to mass-produce the charge generation layer uniformly and with good coating properties. Become. The content of the brominated phenoxy resin is desirably 90% by weight or less.

[0064] Also, photoreceptor No. 1~No. Charging for No. 9 - Photostatic charge removal using light with a wavelength of 780 nm was performed on photoreceptor No.
．． 10~No. For No. 19, charging and optical neutralization using white light were repeated 10,000 times at room temperature and humidity, and then the performance was evaluated at room temperature and humidity. Table 1 shows the results.
0, respectively shown in Table 11.

[0065]

[Table 10]

[0066]

[Table 11]

Values in Tables 10 and 11 and Tables 5 and 8
When compared with the value of photoreceptor No. 7 and no. 18
It can be seen that the sensitivity and residual potential have deteriorated slightly after repeating charging and photostatic discharge 10,000 times. From this, it is considered that including the brominated phenoxy resin in the binder resin of the charge generation layer has the effect of improving durability.

Next, photoreceptor No. 1~No. 9 was attached to a semiconductor laser beam printer (laser jet: manufactured by Hewlett-Packard), and photoconductor No. 10
~No. No. 19 was attached to a copying machine (EP-490Z: manufactured by Minolta), and the image quality was evaluated. First, the initial image quality was evaluated by taking images under low temperature and low humidity, normal temperature and normal humidity, and high temperature and high humidity environments, and then the image quality was evaluated after 10,000 images were taken under normal temperature and normal humidity environments. . Table 1 shows the results.
2, shown in Table 13.

[0069]

[Table 12]

[0070]

[Table 13]

From Tables 12 and 13, photoreceptor No. 7
, No. 8, No. 18, No. It can be seen that although No. 19 can produce good images under normal temperature and normal humidity environments, problems occur in image quality and environmental characteristics under low temperature and low humidity environments or high temperature and high humidity environments. Furthermore, after 10,000 images have been printed, the image quality has deteriorated even in a normal temperature and normal humidity environment, indicating that there is also a problem with durability. The effect of containing the brominated phenoxy resin in the binder resin of the charge generation layer in the range of 5% by weight or more and 90% by weight or less is also evident on the image.

In each of the above evaluations, photoreceptor No. 1 and photoconductor no. It has the same performance as 2. This shows that by including the brominated phenoxy resin in the binder resin of the charge generation layer, there is no need to provide a subbing layer on the conductive substrate.

[0073]

According to the present invention, by including the brominated phenoxy resin represented by the formula (1) in the range of 5% to 90% by weight in the binder resin used for the charge generation layer, the charge generation layer can be improved. A coating for charge generation layers that has good dispersibility and dispersion stability for organic pigments as generation substances, has excellent coating properties, and can mass-produce charge generation layers with good adhesion and excellent charge transport ability. By using this coating liquid, electrophotographic coatings with high sensitivity, excellent durability, stable characteristics even after repeated use over a long period of time, and less fluctuation in characteristics due to changes in temperature and humidity can be obtained. It becomes possible to obtain a photoreceptor.

It is particularly preferable to include a polyvinyl acetal resin together with a brominated phenoxy resin as a binder resin for the charge generation layer, since this improves the dispersibility and dispersion stability of the coating liquid for the charge generation layer.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the content of brominated phenoxy resin in the binder resin of the charge generation layer, the dispersion stability of the coating liquid for the charge generation layer, and the sensitivity of the photoreceptor.

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer including a charge generation layer and a charge transport layer on a conductive substrate, wherein the charge generation layer comprises an organic pigment as a charge generation substance and a binder as a binder. 1. A photoreceptor for electrophotography, wherein the binder resin contains a brominated phenoxy resin represented by the following formula (1) in an amount of 5% by weight or more and 90% by weight or less. embedded image [In formula (1), n represents a positive integer. ] 2. The electrophotographic photoreceptor according to claim 1, wherein the binder resin further contains a polyvinyl acetal resin. 3. An organic pigment as a charge generating substance is dispersed in a first binder resin solution in which only a brominated phenoxy resin as a binder resin is dissolved, and then this dispersion is mixed with a binder resin in which the remaining binder other than the brominated phenoxy resin is dissolved. An electrophotographic photoreceptor comprising the step of mixing and dispersing a resin in a second binder resin solution and then coating the mixed dispersion on a conductive substrate to form a charge generation layer. Production method.