JPH04240861A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body stable in electrophotographic characteristics in successive printing tests and superior in adhesion and image stability against change of temperature and humidity and long in life. CONSTITUTION:The electrophotographic sensitive body is formed by successively laminating on a conductive substrate an undercoat layer containing a binder resin, an electric charge generating layer containing an organic pigment for generating charge and a binder having a water absorbing capacity of <=1.0 wt.% and a charge transfer layer containing a charge transfer material. The difference between the solubility parameter SPBL of the binder resin of the undercoat and that SPCGL of the charge generating layer is controlled to +1.5--1.5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor.

0002

BACKGROUND OF THE INVENTION Electrophotographic photoreceptors using organic photoconductive compounds have recently been widely studied because they are advantageous in terms of flexibility, light weight, surface smoothness, cost, and the like. Among these, functionally separated electrophotographic photoreceptors, which are provided with a charge generation layer that generates charge carriers by light absorption and a charge transport layer that transports the generated charge carriers by an electric field, are conventionally known.
Rapid progress has been made in recent years because the sensitivity, which has been a major drawback of electrophotographic photoreceptors using organic photoconductive compounds, can be greatly improved.

These composite organic electrophotographic photoreceptors are used by being installed in electrophotographic devices (printers, copying machines, etc.) based on the Carlson method.

0004

Problems to be Solved by the Invention Electrophotographic photoreceptors using conventional organic photoconductive compounds have been developed that have good initial characteristics and durability in terms of sensitivity.

However, recently, the printing speed of electrophotographic devices such as copying machines and laser beam printers has become faster.
The apparatuses themselves tend to become smaller, and the process time (charging-exposure-development-erase time) per print also tends to become shorter. Therefore, in terms of electrophotographic properties, electrophotographic photoreceptors have excellent charging properties, fast photoresponsiveness,
In terms of image quality, stability against environmental changes, stability in continuous printing, and mechanical strength, the adhesion of the photoreceptor film is increasingly required. However, by repeating a series of steps such as rapid charging, exposure, development, and erasing, the chargeability of the photoreceptor changes and the sensitivity decreases, resulting in the transferred image becoming unclear or the so-called There have been problems such as deterioration in image quality called fog and peeling of the film on the electrophotographic photoreceptor.

The present inventors have proposed a method for preventing changes in the chargeability of the photoreceptor, deterioration in sensitivity, and deterioration in image quality among these drawbacks (Japanese Unexamined Patent Publication No. 1-118847). Using this method, even in continuous printing, environmental changes and
In particular, the electrophotographic properties do not change much even with changes in temperature and humidity, and electrophotographic properties with good image quality can be obtained. Although there is no practical problem with the adhesion of the film, it is expected that the speed of printers will become faster in the future and the number of prints per surface of the photoreceptor will increase. In this case, it is necessary to further improve the adhesion of the film from the viewpoint of the mechanical life of the photoreceptor. As a method of improving the adhesion of the film and uniformly applying the charge generation layer to improve the image quality, there is a method of using phenoxy resin as a resin binder used as a binding agent for the charge generation layer (Japanese Patent Application Laid-open No. 196766/1983, Same 6
No. 0-232554, No. 61-65252,
63-33747, 63-243961), a method of using melamine resin or benzoguanamine resin in combination with polyvinyl butyral, polyester resin, or phenoxy resin (JP-A-62-242953, 63-243961).
Publication No. 3-85562, Publication No. 63-187248,
63-271451) and the like have been proposed. These methods are effective in improving adhesion, but
It is insufficient in terms of electrophotographic properties. That is, in a continuous printing test, a decrease in charging potential (Vo), an increase in residual potential (Vr), etc. occur, resulting in a decrease in density and fog. Also,
There is a problem in that the performance of the photoreceptor changes significantly due to environmental changes, particularly environmental humidity, and image defects such as black spots, white spots, and fog are more likely to occur due to a decrease in charging potential.

The present invention has been made in view of the above points, and has excellent adhesion, stable electrophotographic characteristics in continuous printing tests, and excellent image quality stability against changes in temperature and humidity. The purpose is to obtain a long-life electrophotographic photoreceptor.

[0008]

[Means for Solving the Problems] That is, the present invention comprises, on a conductive substrate, an undercoat layer containing a binder resin, an organic pigment that generates a charge, and a binder having a water absorption rate of 1.0 wt% or less. In an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer containing a charge transporting substance are sequentially laminated, the solubility parameter (SPBL) of the binder contained in the undercoat layer and the binder resin of the charge generation layer are Solubility parameter (SP
CGL) difference (SPBL-SPCGL) is +1.5 to -
1.5.

[0009] Solubility parameter (SPB
L and SPCGL) are R. F. Fedors method (
Polym. Eng. Sci. , 14, 147 (197
4)). When determining solubility parameters using this method, the chemical structure of the binder resin and binder must be known. The chemical structure can be found in the catalogs of binder resin and binder manufacturers and in
It can be determined from analytical data such as H-NMR, IR, and GPC. Further, as the solubility parameter of the thermosetting resin, a value that can be determined from the structure before reaction may be used.

[0010] SPBL-SPCGL is +1.5 to -1
．． It is essential that it be in the range of 5. It is preferably in the range of 0 to -1.5, more preferably 0 to -0.6. Outside this range, the effects of the present invention will not be achieved.

[0011] The water absorption rate in the present invention is determined by dissolving the binder contained in the charge generation layer in a good solvent (resin solution with solid content of 5%).
After that, it was dried at 140℃ for 1 hour, and then heated to NH4H2 at 25℃.
It was determined from the weight change after being left in a PO4 saturated solution environment (93% RH) for 100 hours.
5)).

[0012] The water absorption rate is essential to be 1.0 wt% or less, preferably 0.7 wt% or less,
More preferably, it is 0.5 wt% or less. Outside this range, the effects of the present invention will not be achieved.

[0013] As the conductive substrate, conductive materials such as conductively treated paper or plastic film, plastic film laminated with metal foil such as aluminum, metal plate, metal drum, etc. can be used.

A known undercoat layer is provided on such a conductive substrate.

[0015] The undercoat layer in the present invention comprises fine particles and/or
Alternatively, a solution prepared by dispersing and dissolving the binder resin in a solvent is applied onto the conductive substrate using a coating method such as dip coating, spray coating, roll coating, applicator coating, or wire bar coating, and then dried. It can be formed by

Examples of the fine particles include fine particles of titanium oxide, aluminum oxide, zirconia, lanthanum lead zirconate titanate, alumina, titanium black, silica, lead titanate, barium titanate, and the like.

Examples of the binder resin include polyamide resin, phenol resin, casein, melamine resin, benzoguanamine resin, polyurethane resin, epoxy resin, cellulose, and polyvinyl butyral resin. These fine particles and binder resin can be used alone or in combination of two or more.

In particular, when fine particles are used, it is desirable to use them together with a resin because a smooth film can be obtained by adsorbing the fine particles to the resin.

Examples of the solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, toluene, ethyl acetate, methylene chloride, toluene, xylene, cellosolve, 1,1,2-trichloroethane, methanol, isopropyl alcohol, isobutyl alcohol, Solvents include n-butyl alcohol and 1,2-dichloroethane. The thickness of the undercoat layer is usually 0.01 to 10.0 μm, preferably 0.1 to 3.0 μm.
It is 0 μm. When this thickness is less than 0.01 μm,
It tends to be difficult to form an undercoat layer uniformly,
If it exceeds 10.0 μm, electrophotographic properties tend to deteriorate.

The charge generation layer contains an organic pigment and a binder that generate charges, a plasticizer used as necessary, a curing catalyst,
After uniformly dissolving or dispersing additives such as flowability agents and pinhole control agents in the same solvent used to form the undercoat layer, dip coating or spray coating is applied onto the undercoat layer. It can be formed by coating using a coating method such as a coating method, a roll coating method, an applicator coating method, or a wire bar coating method, and then drying it.

[0021] As the charge-generating organic pigment, known ones can be used, such as azoxybenzene type,
Organic pigments such as disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, naphthalocyanine, pyrrolopyrrole, perylene, and methine can be used.

[
Examples of the binder include silicone resin, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polystyrene resin, polymethacrylate resin,
Polyacrylamide resin, polybutadiene resin, polyisoprene resin, melamine resin, benzoguanamine resin,
Polychloroprene resin, polyacrylonitrile resin, ethyl cellulose resin, nitrocellulose resin, urea resin, phenol resin, phenoxy resin, polyvinyl butyral resin, formal resin, vinyl acetate resin, vinyl acetate/vinyl chloride copolymer, polyester carbonate resin, etc. It will be done. A single substance or a blend of two or more of these resins may be used. In particular, resins (thermal and/or photocurable resins) that are electrically insulating and do not dissolve in the solvent of the charge transport layer are preferred. If the binder resin contained in the undercoat layer used changes, the binder contained in the charge generation layer changes accordingly, but in any case, SPBL-SPCG
It is sufficient if L=+1.5 to -1.5 is satisfied.

The water absorption rate of the binder contained in the charge generation layer is 1
．． It is set to be 0wt% or less. The content is preferably 0.7 wt% or less. If the water absorption rate is too high, the image quality and humidity resistance during repeated use will be poor. The amount of binder in the charge generating layer is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight, based on 100 parts by weight of the photoconductive material. If the amount is less than 5 parts by weight, the binder will not be sufficiently adsorbed to the photoconductive substance, so that the film of the charge generation layer will tend to be non-uniform and the image quality will tend to be poor. If it exceeds 200 parts by weight,
Sensitivity tends to decrease and residual potential increases.

[0024] Examples of the plasticizer include halogenated paraffin, dimethylnaphthalene, dibutyl phthalate, and the like. Examples of the curing catalyst include sulfonsane-based catalysts such as methanesulfonic acid, dodecylbenzenesulfonic acid, and dinonylnaphthalenedisulfonic acid. Examples of the fluidity imparting agent include Modaflow (manufactured by Monsanto Chemical Company) and Acronal 4F (manufactured by Basf Company). Examples of pinhole control agents include benzoin and dimethyl phthalate. these are,
It is preferable to use each in an amount of 5 parts by weight or less based on the charge-generating organic pigment.

The thickness of the charge generation layer is usually 0.01 to 2.
0 μm, preferably 0.1 to 0.8 μm. If the thickness is less than 0.01 μm, it tends to be difficult to uniformly form the charge generation layer;
If it exceeds 20%, the electrophotographic properties tend to deteriorate.

A charge transport layer is provided on the charge generation layer formed as described above. The charge transport layer includes a charge transport material, a binder, and other additives.

To form the charge transport layer, the charge transport material, binder, and additives are uniformly dissolved in a solvent similar to that used to form the charge generation layer, and then this solution is added to the charge generation layer. It can be formed by applying a coating thereon using a coating method such as a dip coating method, a spray coating method, a roll coating method, an applicator coating method, a wire bar coating method, or the like, and drying it.

Examples of the charge transport substance include fluorene, fluorenone, 2,7-dinitro-9-fluorenone, and 4H-indeno(1,2,6)thiophene-
4-one, 3,7-dinitro-dibenzothiophene-5
-oxide, 1-bromopyrene, 2-phenylpyrene,
Carbazole, 3-phenylcarbazole, 2-phenylindole, 2-phenylnaphthalene, oxazole, oxadiazole, oxatriazole, triphenylamine, imidazole, chrysene, tetraphene, acridene, various hydrazones, styryl compounds, poly-
N-vinylcarbazole, halogenated poly-N-vinylcarbazole, 1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, polyvinylpyrene, 2-phenyl-4-(4
-diethylaminophenyl)-5-phenyloxazole, polyvinylindoquinoxaline, 1,1-bis(
p-diethylaminophenyl)-4,-4diphenyl-
Examples include 1,3-butadiene, polyvinylbenzothiophene, polyvinylanthracene, polyvinylacridine, polyvinylpyrazoline, and derivatives thereof.

As the binder, the same binder as in the charge generation layer can be used. The binder is desirably used in an amount of 450 parts by weight or less per 100 parts by weight of the charge transport material to avoid deterioration of electrophotographic properties, and for low-molecular charge transport materials, it is preferably used in an amount of 50 parts by weight or less in view of film properties. The above is desirable. Further, the charge transport layer may contain additives similar to those in the charge generation layer, such as a plasticizer, a fluidity imparting agent, and a pinhole control agent, if necessary. Preferably, each additive is used in an amount of 5 parts by weight or less based on the charge transport material.

The thickness of the charge transport layer is usually 5 to 50 μm, preferably 8 to 30 μm. This thickness is 5
If it is less than μm, the potential tends to be low at the initial stage.
If it exceeds 50 μm, electrophotographic properties tend to deteriorate.

In the electrophotographic photoreceptor of the present invention, a protective layer may be formed on the charge transport layer. The thickness of the protective layer is
0.01 to 10 μm, preferably 0.1 to 3 μm
It is m. If the thickness is less than 0.01 μm, the protective layer tends to be less effective and has poor durability, and if it exceeds 10 μm, the sensitivity tends to decrease and the residual potential increases.

When printing is performed using the electrophotographic photoreceptor of the present invention, the image may be charged and exposed in the conventional manner, then developed, and the image transferred onto plain paper and fixed.

[0033]

[Examples] Next, the present invention will be explained in detail by examples.
The present invention is not limited to these. Unless otherwise specified, "%" means "% by weight".

The materials used in the following examples are listed below. Abbreviations are shown in parentheses. (1) Fine particle lead zirconate titanate (PLZT) for undercoat layer (manufactured by Sumitomo Cement Co., Ltd.) (2) Organic pigment τ-type metal-free phthalocyanine (τ-H2Pc) that generates electric charge (manufactured by Toyo Ink Co., Ltd.) (3) Charge transport substance 1,1-bis(p-diethylaminophenyl)-4,4
-diphenyl-1,3-butadiene (PBD)

003
5]

[Chemical formula 1]

(4) Binder (A) For undercoat layer Resin with the following structure MX1970 (MX1970) Solid content 100% (manufactured by Nippon Rilsan Co., Ltd.)

[0037]

[Case 2] Resin with the following structure VP16 (VP16) Solid content 50% (manufactured by Hitachi Chemical)

[0038]

[Formula 3] The number of formaldehyde bonds is 4.0, and the number of methylol groups is 1.
0 butylated melamine resin Melan 2000 (ML2000) Solid content 50% (manufactured by Hitachi Chemical)

(B) Bisphenol A polycarbonate resin Lexan 141 for charge generation layer
(L141) Solid content 100% (manufactured by GE)

[0040]

[C4] Butyl methacrylate resin Elbasite 2045 (E2045) Solid content 100% (manufactured by GE)

[0041]

[C5] polyester resin Byron 290 (V290) Solid content 100% (manufactured by Toyobo Co., Ltd.)

[0042]

[C6] Brominated phenoxy resin YPB-43 (YPB-43) Solid content 100% (manufactured by Toto Kasei Co., Ltd.)

[0043]

[C7] Resin shown by the structural formula below A-ST-1　Solid content 100% (manufactured as below)

[0044]

[Chemical formula 8] A-ST-2　Solid content 100% (manufactured as below)

[0045]

[Chemical formula 9] A-ST-3　Solid content 100% (manufactured as below)

[0046]

[Chemical formula 10]

Synthesis of prepolymer In a four-neck flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, 600 parts of toluene, 80 parts of p-tert-butoxystyrene, and 0.2 parts of azobisisobutyronitrile were added.
0 part was added, and nitrogen substitution was sufficiently performed. Next, the contents were heated to 80° C. over 30 minutes with stirring, kept at this temperature for 3 hours, then heated to 110° C. and kept at this temperature for 8 hours. After cooling the resulting reaction mixture, it was added to 3 liters of cold methanol to produce a white precipitate, which was filtered and dried. The yield was 27 parts (yield 33.8%).

When the molecular weight was measured using a high performance liquid chromatograph (hereinafter abbreviated as HLC), the number average molecular weight was 19.
,000, and the weight average molecular weight was 48,000. On the other hand, nuclear magnetic resonance absorption spectrum (hereinafter abbreviated as NMR)
When measured, aromatic content was found to be 6.3 to 6.6 ppm.
tert-butyl group and methylene group at 1.25 ppm,
In addition, a methine group broton signal was observed at 1.7 ppm. From these data, the product is p-tert-
It was confirmed that it was butoxystyrene polymer.

Synthesis of A-ST-1 5.0 parts of the p-tert-butoxystyrene polymer obtained in the synthesis of the prepolymer and 0.92 parts of concentrated hydrochloric acid were mixed with 50 parts of dioxane.
The mixture was placed in a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube. After raising the temperature of the flask to 60°C and keeping it at this temperature for 5 hours, it was heated to about 1/3 under reduced pressure.
It was then added dropwise to 100 ml of cold toluene, and the precipitate was filtered and dried. The obtained precipitate was dissolved in 15 ml of dioxane, and then reprecipitated with toluene. This operation was repeated twice for purification and then thoroughly dried to obtain 3.5 parts of polymer.

This polymer was analyzed by infrared absorption spectrum and NM
When analyzed by R, hydroxyl group (tert-butanol was removed from tert-butoxy group to generate hydroxyl group)
was recognized. Polymer hydroxyl group/t from NMR chart
The ratio of ert-butoxy groups was determined to be 50/50 (
molar ratio).

Synthesis of A-ST-2 5.0 parts of the p-tert-ptoxystyrene polymer obtained in the synthesis of the prepolymer and 0.38 parts of concentrated hydrochloric acid were mixed with 5.0 parts of dioxane.
The mixture was dissolved in 0 parts and placed in a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube. flask at 60℃
After raising the temperature to
The mixture was concentrated to a volume of 3 and added dropwise to 100 ml of cold toluene, and the precipitate was filtered and dried. The obtained precipitate was dissolved in 15 ml of dioxane, and then reprecipitated with toluene. This operation was repeated twice for purification and then thoroughly dried to obtain 3.5 parts of polymer.

This polymer was analyzed by infrared absorption spectrum and NM
When analyzed by R, hydroxyl group (tert-butanol was removed from tert-butoxy group to generate hydroxyl group)
was recognized. Polymer hydroxyl group/t from NMR chart
The ratio of ert-butkin groups was determined to be 10/90 (
molar ratio).

Synthesis of A-ST-3 5.0 parts of the p-tert-butoxystyrene polymer obtained in the synthesis of the prepolymer and 0.79 parts of concentrated hydrochloric acid were mixed with 50 parts of dioxane.
The mixture was placed in a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube. After raising the temperature of the flask to 60°C and keeping it at this temperature for 5 hours, it was heated to about 1/3 under reduced pressure.
It was then added dropwise to 100 ml of cold toluene, and the precipitate was filtered and dried. The obtained precipitate was dissolved in 15 ml of dioxane, and then reprecipitated with toluene. This operation was repeated twice for purification and then thoroughly dried to obtain 3.5 parts of polymer.

This polymer was analyzed by infrared absorption spectrum and NM
When analyzed by R, hydroxyl group (tert-butanol was removed from tert-butoxy group to generate hydroxyl group)
was recognized. Polymer hydroxyl group/t from NMR chart
The ratio of ert-butoxy groups was determined to be 30/70 (
molar ratio).

[0055] Butylated benzoguanamine resin (BG
A) Solids content 60% (manufactured as follows)

[0056] Into a flask equipped with a stirrer and a reflux condenser, 187 g (1 mol) of benzoguanamine, 222 g (3 mol) of n-butanol, and 93.75 g (2.5 mol) of 80% paraformaldehyde were weighed. The temperature was raised to ℃ and the addition reaction was carried out for 1 hour. Then add dilute nitric acid to adjust the pH.
The temperature was adjusted to 5.0, and heating was performed again. While refluxing,
Dehydration was performed for 3 hours. Then, start desolventizing at the same temperature.
The time point when the temperature reached 130°C was defined as the end point of solvent removal. After this,
It was diluted with Sorbetsuso-100 so that the heating residue was 60%. The viscosity at this time was S (Gardna/25°C).

The number of bound formaldehyde and the number of methylol groups per triazine nucleus of BGA were determined by 1H-NMR.

(C) For charge transport layer polycarbonate resin Lexan 141-111 (L141) Solid content 100% (manufactured by GE)

Comparative Example 1 35g of MX1970, 70g of ML2000 and 2.
1g of trimellitic acid is mixed with methanol and methylene chloride.
:1 (weight ratio, the same applies hereinafter) in 1800 g of a mixed solvent. This solution was poured into an aluminum drum (diameter 6
0.1 mm x 247 mm in length) using a dip coating method and dried at 120° C. for 60 minutes to form an undercoat layer with a thickness of 0.3 μm.

The solubility parameter (SPBL) of this undercoat layer binder was determined by the Fedors method.12
．． It was 64.

Next, 50g of τ-H2Pc, 40g of L
1,850 g of a mixed solvent of 141, tetrahydrofuran and 1,2-dichloromethane in a ratio of 1:1 (weight ratio, the same applies hereinafter) was dispersed for 10 hours using an ultrasonic disperser. The resulting dispersion was applied onto the undercoat layer using a dip coating method, and
It was dried at .degree. C. for 60 minutes to form a charge generation layer with a thickness of 0.3 .mu.m.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 10.54.

Therefore, SPBL-SPCGL is +
It is 2.10. Further, the water absorption rate of this charge generation layer binder was 0.32wt.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1200 g of a mixed solvent of methylene chloride and 1,1,2-trichloroethane at a ratio of 1:1 (weight ratio, the same applies hereinafter). This solution was coated on the charge generation layer having the undercoat layer by a dip coating method, and dried at 120° C. for 60 minutes to form a charge transport layer having a thickness of 20 μm, thereby forming an electrophotographic photoreceptor.

Comparative Example 2 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 40 g of E
1,850 g of a 1:1 mixed solvent of No. 2045, methylene chloride, and 1,1,2-trichloroethane were dispersed for 10 hours using an ultrasonic disperser. The resulting dispersion was applied onto the above-mentioned undercoat layer by dip coating and dried at 140° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solvent property parameter (SPCGL) of this charge generating layer binder was determined to be 10.77.

Therefore, SPBL-SPCGL is +
It is 1.87. Further, the water absorption rate of this charge generation layer binder was 0.42 wt%.

Next, 50 g of PBD and 150 g of R1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Comparative Example 3 36g of VP16, 4g of ML2000 and 20g of P
LZT was completely dissolved and dispersed in 1800 g of a 1:1:2 mixed solvent of ethanol, 1,1,2-trichloroethane, and THF. This solution was poured into an aluminum drum (diameter 60
．． 1 mm in length and 247 mm in length) by a dip coating method, and dried at 180° C. for 60 minutes to form an undercoat layer with a thickness of 0.3 μm.

The solubility parameter (SPBL) of this undercoat layer binder was determined using the Fedors method.12
．． It was 13.

Next, 50g of τ-H2Pc, 40g of L
141, 1850 g of a 1:1 mixed solvent of tetrahydrofuran and 1,2-dichloromethane was dispersed for 10 hours using an ultrasonic disperser. The resulting dispersion was applied onto the above-mentioned undercoat layer by dip coating and dried at 140° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 10.54.

Therefore, SPBL-SPCGL is +
It is 1.59. Further, the water absorption rate of this charge generation layer binder was 0.32 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1200 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Comparative Example 4 Using the materials and procedures shown in Comparative Example 3, an undercoat layer with a thickness of 0.3 μm was formed on aluminum Domura (diameter 60.1 mm, length 247 mm).

Next, 50g of τ-H2Pc, 19.2g
of V290, 12.8g of YPB43, 13.3g of B
1:1 of GA, THF and 1,1,2-trichloroethane
1850 g of the mixed solvent was dispersed for 10 hours using an ultrasonic disperser. The resulting dispersion was applied onto the undercoat layer using a dip coating method, and dried at 140°C for 60 minutes to give a film thickness of 0.3.
A charge generation layer of .mu.m was formed.

The solubility parameter (SPCGL) of this charge generation layer binder was determined to be 13.73.

Therefore, SPBL-SPCGL is -
It is 1.60. Further, the water absorption rate of this charge generation layer binder was 0.70 wt%.

Next, 50 g of PBD and 150 g of R1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was applied to the charge generation layer having the undercoat layer by a dip coating method and dried at 120° C. for 60 minutes to form a charge transport layer having a thickness of 20 μm, thereby forming an electrophotographic photoreceptor.

Comparative Example 5 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 40 g of A
-ST-1 and 1850 g of tetrahydrofuran were dispersed for 10 hours using an ultrasonic disperser. The obtained dispersion was coated on the above-mentioned undercoat layer using a dip coating method, and then heated at 140°C for 60°C.
A charge generation layer having a thickness of 0.3 μm was formed by drying for 1 minute.

The solubility parameter (SPCGL) of this charge generating layer binder was determined to be 11.83.

Therefore, SPBL-SPCGL is +
It is 0.81. Further, the water absorption rate of this charge generation layer binder was 1.10 wt%.

Next, 50 g of PBD and 150 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Comparative Example 6 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 32 g of A
-ST-1, 16g of BGA and tetrahydrofuran and 1
, 1:1 mixed solvent of 1,2-trichloroethane 185
0 g was dispersed for 10 hours using an ultrasonic disperser. Coating the obtained dispersion onto the undercoat layer using a dip coating method,
It was dried at 140° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined to be 12.03.

Therefore, SPBL-SPCGL is +
It is 0.61. Further, the water absorption rate of this charge generation layer binder was 1.20 wt%.

Next, 50 g of PBD and 150 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 1 Using the materials and procedures shown in Comparative Example 1, a 0.3 μm thick undercoat layer was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 36 g of V
290, 7g BGA, tetrahydrofuran and 1,2-
1850 g of a 1:1 mixed solvent of dichloromethane was dispersed for 10 hours using an ultrasonic disperser. The obtained dispersion was coated on the above-mentioned undercoat layer by a dip coating method, and then coated at 140°C for 6 hours.
After drying for 0 minutes, a charge generation layer with a thickness of 0.3 μm was formed.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 12.65.

Therefore, SPBL-SPCGL is -
It is 0.01. Further, the water absorption rate of this charge generation layer binder was 0.40 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 2 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50g of τ-H2Pc, 19.2g
of V290, 12.8 of YPB-43, 13.5g of B
GA, 1900 g of a 1:1 mixed solvent of tetrahydrofuran and 1,2-dichloromethane were added to 1:1 using an ultrasonic disperser.
Dispersed for 0 hours. The resulting dispersion was applied onto the above-mentioned undercoat layer by dip coating and dried at 140° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 13.73.

Therefore, SPBL-SPCGL is -
It is 1.09. Further, the water absorption rate of this charge generation layer binder was 0.70 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 3 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50g of τ-H2Pc, 25.6g
of V290, 6.4g of YPB-43, 13.5g of B
GA, 1900 g of a 1:1 mixed solvent of tetrahydrofuran and 1,2-dichloromethane were added to 1:1 using an ultrasonic disperser.
Dispersed for 0 hours. The resulting dispersion was applied onto the above-mentioned undercoat layer by dip coating and dried at 140° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 13.19.

Therefore, SPBL-SPCGL is -
It is 0.55. Further, the water absorption rate of this charge generation layer binder was 0.80 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 4 Using the materials and procedures shown in Comparative Example 3, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 36 g of V
290, 6.7g BGA, tetrahydrofuran and 1,
1900 g of a 1:1 mixed solvent of 2-dichloromethane was dispersed for 10 hours using an ultrasonic disperser. The obtained dispersion was coated on the above-mentioned undercoat layer by dip coating method and heated at 140°C.
This was dried for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generation layer binder was determined by the Fedors method and was 12.65.

Therefore, SPBL-SPCGL is -
It is 0.52. Further, the water absorption rate of this charge generation layer binder was 0.40 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 5 Using the materials and procedures shown in Comparative Example 3, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50g of τ-H2Pc, 25.6g
of V290, 6.4g of YPB-43, 13.5g of B
GA, 1900 g of a 1:1 mixed solvent of tetrahydrofuran and 1,2-dichloromethane were added to 1:1 using an ultrasonic disperser.
Dispersed for 0 hours. The resulting dispersion was applied onto the above-mentioned undercoat layer by dip coating and dried at 140° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by Fedors' method and was 13.19.

Therefore, SPBL-SPCGL is -
It is 1.06. Further, the water absorption rate of this charge generation layer binder was 0.80 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 6 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 32 g of A
-ST-2, 13.3g BGA, 1:1 mixed solvent of tetrahydrofuran and 1,2-dichloromethane 1900
g was dispersed for 10 hours using an ultrasonic disperser. Obtained. The dispersion was coated on the undercoat layer using a dip coating method, and 1
It was dried at 40° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 11.31.

Therefore, SPBL-SPCGL is +1
．． It is 33. Further, the water absorption rate of this charge generation layer binder was 0.65 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

Example 7 Using the materials and procedures shown in Comparative Example 1, a subbing layer with a thickness of 0.3 μm was formed on an aluminum drum (diameter 60.1 mm, length 247 mm).

Next, 50 g of τ-H2Pc, 32 g of A
-ST-3, 13.3g BGA, 1:1 mixed solvent of tetrahydrofuran and 1,2-dichloromethane 1900
g was dispersed for 10 hours using an ultrasonic disperser. The obtained dispersion was coated on the above-mentioned undercoat layer by dip coating method, and 1
It was dried at 40° C. for 60 minutes to form a charge generation layer with a thickness of 0.3 μm.

The solubility parameter (SPCGL) of this charge generating layer binder was determined by the Fedors method and was 11.67.

[0124] Therefore, SPBL-SPCGL is +
It is 0.97. Further, the water absorption rate of this charge generation layer binder was 0.90 wt%.

Next, 60 g of PBD and 140 g of L1
41 was completely dissolved in 1400 g of a 1:1 mixed solvent of methylene chloride and 1,1,2-trichloroethane. This solution was coated on the charge generation layer having the undercoat layer by dip coating method, and dried at 120°C for 60 minutes to obtain a film thickness of 20 μm.
A charge transport layer was formed to form an electrophotographic photoreceptor.

The adhesion, electrophotographic properties, images, and image durability of the electrophotographic photoreceptors obtained in the Comparative Examples and Examples were evaluated.

[0127] Adhesion was evaluated by the number remaining after a cross-cut test using a grid test.

The electrophotographic characteristics were measured using a light attenuation measuring device (Cynthia 30, manufactured by Midoriya Electric Co., Ltd.) at a Vo of -700.
Dark decay (DDR5) at the initial stage and after printing 200,000 sheets,
The residual potential (Vr) and sensitivity (E5o) after 0.3 seconds were evaluated.

[0129] For DDR5, the potential (V5) was measured after 5 seconds in the dark and was expressed as (V5/Vo) x 100 (%). E5o
When irradiated with light with a wavelength of 780 nm, Vo is -350
It is expressed as the energy required to reach v. Vr is 20
The surface potential when irradiated with energy of mJ/m2 (wavelength 7800 nm) is shown.

[0130] The image and the durability of the image were evaluated by using an image evaluation machine (negative charging, reversal development method) to evaluate the image quality at the initial stage and after printing 200,000 sheets.

[0131] The humidity resistance of the image is
After being left in an environment of 0°C and 90% RH for 72 hours, the image evaluation machine (
The image quality was evaluated using a negative charging, reversal development method).

Tables 1 and 2 show the evaluation results of adhesion, electrophotographic properties at the initial stage and after printing 200,000 sheets, image quality at the initial stage and after printing 200,000 sheets, and humidity resistance.

From the results shown in Tables 1 and 2, Comparative Example 1,
Electrophotographic photoreceptors Nos. 2 and 4 had poor adhesion, so the film peeled off during the test using an image evaluation machine. Comparative example 3
In the case of the electrophotographic photoreceptor, after 200,000 sheets were printed, Vr increased and the image density decreased. The electrophotographic photoreceptors of Comparative Examples 5 and 6 have excellent adhesion, so the film does not peel off during the test with an image evaluation machine, but after printing 200,000 sheets, the Vr
has increased, resulting in a decrease in image density. Also,
Fog occurred in the image after humidity resistance.

On the other hand, the electrophotographic photoreceptor of the present invention has excellent adhesion, image durability, and image resistance to humid environments, so it is fully applicable to high-speed printers that require high-speed response. .

[0135]

[Table 1]

[0136]

[Table 2]

[0137] In the undercoat layer containing fine particles and the charge generation layer containing organic pigment, the binder resin adsorbs to the inorganic fine particles and organic pigment and envelops them, so the adhesion depends on the binder resin of the undercoat layer and charge generation layer. It is thought that it depends on the difference in solubility parameters.

[0138]

[Effects of the present invention] The electrophotographic photoreceptor of the present invention has excellent adhesion,
Since it has excellent electrophotographic properties and image durability, it is fully applicable to high-speed printers as a long-life photoreceptor.

Claims (4)

[Claims] Claim 1: A conductive substrate, an undercoat layer containing a binder resin, an organic pigment that generates a charge, and a water absorption rate of 1.0 W.
In an electrophotographic photoreceptor comprising a charge generating layer containing a binder of t% or less and a charge transporting layer containing a charge transporting substance, the solubility parameter SPBL of the binder resin contained in the undercoat layer and the Difference in solubility parameter SPCGL of the binder contained in the charge generation layer (SPBL-SP
CGL) is +1.5 to -1.5. 2. The binder contained in the charge generation layer comprises:
The electrophotographic photoreceptor according to claim 1, comprising a thermosetting resin and at least one thermoplastic resin. 3. The thermosetting resin has a triazine nucleus 1
3. The electrophotographic photoreceptor according to claim 2, which is an alkyl etherified benzoguanamine resin having 1.5 to 3.0 formaldehyde bonds and 2.0 or less methylol groups per unit. 4. The electrophotographic photoreceptor according to claim 1, wherein the organic pigment that generates charges is a phthalocyanine pigment.