JPS6336254A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form an image free from uneven density by dispersing a squaric acid derivative in an electric charge generating layer and using as the interface between the charge generating layer and a low-resistivity surface protective layer a charge injection blocking interface. CONSTITUTION:The photosensitive body is obtained by successively laminating on a conductive substrate 1 made of Al, Cu, Fe, or the like, a charge transfer layer 2 composed of a charge transfer material, such as pyrene, and a binder resin, such as acrylic resin, and the charge generating layer 3 containing the charge generating material 5, such as a squaric acid derivative, dispersed in the binder resin in an amount of 20-50wt%, and further, the low-resistivity surface protective layer 4 containing a conductive metal oxide dispersed in it, having a resistivity of 10<9>-10<14>OMEGA.cm. The charge injection blocking accessary layer 8 is formed between layer 4 and the layer 3 as the charge injection blocking interface by using a coupling agent, such as a silane coupling agent or titanium coupling agent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved electrophotographic photoreceptor. BACKGROUND OF THE INVENTION Conventionally, there have been many configurations of laminated organic photoreceptors in which a charge generation layer is laminated as a lower layer of a charge transport layer. Since most of the charge transport layers generally known at present have hole transport properties, this configuration has no choice but to use a negatively charged layer. In the past, they had various drawbacks that affected the photoreceptor, such as the generation of high concentrations of ozone due to negative charging, and uneven charging due to rototrometry. In order to overcome this drawback, a charge generation layer is laminated as an upper layer of a charge transport layer and used with positive charging, and in order to further improve mechanical strength and deterioration, a low resistance surface protective layer is added as the top layer. Laminated configurations have been tried. Problems to be Solved by the Invention However, with such a layer structure, sufficient chargeability cannot be obtained and only a low contrast potential can be obtained, or even if chargeability is sufficient, optical attenuation is insufficient. The residual potential is high, and the charged potential changes due to changes in temperature and humidity.
It had various drawbacks, such as the residual potential fluctuating, the charged potential and residual potential changing during repeated use, and the sensitivity decreasing significantly compared to before applying the surface protective layer. . The present invention was made to solve these drawbacks, and it prevents a decrease in charging potential, a high residual potential, the effects of temperature and humidity, and a decrease in sensitivity, and reduces the charging potential and residual potential during repeated use. This provides a stable electrophotographic photoreceptor. Means and Effects for Solving the Problems The electrophotographic photoreceptor of the present invention comprises a charge transport layer, a charge generation layer and a low resistance surface protection layer laminated in this order on a conductive support. A squaric acid derivative is dispersed in the layer, and the interface between the charge generation layer and the low resistance surface protective layer is a charge injection blocking interface. Next, the electrophotographic photoreceptor of the present invention will be explained with reference to the drawings. 1 to 4 are schematic diagrams each not showing the specific structure of the electrophotographic photoreceptor of the present invention. FIG. 1 shows a typical configuration, in which a charge transport layer 2 and a charge generation layer 3 in which a charge generation material 5 is dispersed are sequentially laminated on a conductive support 1, and a conductive support 1 is further laminated. A low resistance surface protective layer 4 in which metal oxide 6 is dispersed is formed. In FIG. 2, an adhesive layer 7 is provided between the conductive support 1 and the charge transport layer 2, and in FIG. Further, in FIG. 4, an adhesive layer 7 is provided between the conductive support 1 and the charge transport layer 2.
However, a charge injection blocking auxiliary layer 8 is also provided between the charge generation layer 3 and the low resistance surface protection H4. Next, each layer constituting the electrophotographic photoreceptor of the present invention will be explained. The conductive support in the electrophotographic photoreceptor of the present invention includes a drum or sheet of metal such as aluminum, copper, iron, zinc, and nickel, and aluminum, copper, gold, silver, platinum, etc. on paper, plastic, or glass. Deposit metals such as palladium, titanium, nickel-chromium, stainless steel, copper-indium, conductive metal compounds (e.g. n203.5n02), laminate metal foils, or carbon Black, conductive metal compound (e.g., In 203, S b 203-8nO
2, S rl O2, T10X) powder, metal powder, etc., are dispersed in a binder resin and applied to conductive treatment, such as drum-shaped, sheet-like plate-shaped ones, etc. are used. The charge transport layer in the electrophotographic photoreceptor of the present invention is composed of a charge transport material and a binder resin. Charge transport materials include pyrene, N-ethylcarbazole, N-isopropylcarbazole, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3-(p-diethylaminostyryl). )-5-(p-
diethylaminophenyl)pyrazoline, 1-[pyridyl=(2)]-3-(p-diethylaminostyryl)-5
-(1)-diethylaminophenyl)pyrazoline, 1-
[Quinolyl-(2)]-3-(F)-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-heliphenylamine, N,N''-diphenyl-
N,N--bis(3-methylphenyl)-'[1,1"
-Bifinyl]-4゜4'-diamine, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4,4'-benzylidene-his(N,N--diethyl-m-1~luidine, poly-N - vinyl carbazole,
Halogenated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-
Examples include formaldehyde resin, ethylcarbazole-formaldehyde resin, and the like. These charge transport materials can be used alone or in a mixture of two or more. Charge transport materials are not limited to those described herein. As the binder resin used in the charge transport layer, general-purpose resins such as acrylic resin, methacrylic resin, polystyrene, polyester, polyarylate, polysulfone, and polycarbonate, and hole-transporting polymers such as poly-N-vinylcarbazole are used. Can be used. Note that an adhesive layer may be provided between the conductive support and the charge transport layer. -〇- The charge generation layer in d3 of the Nomiko photographic photoreceptor of the present invention is prepared by dispersing a squaric acid derivative as a charge generation material in a binder resin in an amount of 5 to 90 parts by weight, preferably 20 to 50 parts by weight. Contains Preferably used squaric acid derivatives are those represented by the following structural formula (1)', IV). 〇- (IV) These squaric acid derivatives have a particle size of 0.021
A thickness of 1 m to 3 μm, preferably 0.05 μm to 1 μm is used. As the binder resin for the charge generation layer, polyvinyl butyral, polyester, polycarbonate, phenoxy resin,
Various resins are used, such as acrylic resin, polyacrylamide, polyamide, polyvinylpyridine resin, casein, polyvinyl alcohol, and poly-N-vinylcarbazole. The low-resistance surface protective layer of the electrophotographic photoreceptor of the present invention is a layer in which fine particles of a conductive metal oxide are dispersed in an insulating resin, and the conductive metal oxide has an electrical resistance of 109.
Fine particles with an average particle size of 0.3 μm or less, preferably 0.1 μm or less that are white, gray, or bluish-white in color and are Ω・cm or less, such as antimony oxide, tin oxide, titanium oxide, and Examples include solid solutions of indium, tin oxide and antimony or antimony oxide, or mixtures thereof, or mixtures or coatings of these metal oxides in particles. Among these, solid solutions of tin oxide and ammonium oxide or antimony oxide, or tin oxide (51°) are preferably used because they can lower the electrical resistance and make the protective layer substantially transparent. (Special Open Show 57-3
(Refer to No. 0847, Japanese Unexamined Patent Publication No. 57-12834.4)
. The electrical resistance of the low resistance surface protective layer is 109 to 1014Ω.
・It is desirable to configure it so that it is cm. If the electrical resistance exceeds 1014Ω・cm, the residual potential will increase and the resulting copies will have a lot of fog.
・When the distance is less than cm, the image becomes blurred and the resolution decreases. Furthermore, the low resistance surface protective layer must be constructed so as not to substantially impede the passage of light used for imagewise exposure. If the particle size of the conductive metal oxide used is too large, the low resistance surface protective layer becomes opaque, resulting in desensitization and a decrease in image density. The particle size is determined by the wavelength of light used for image exposure (0, 4,
It is desirable to use particles having a particle diameter of 0.3 μm or less, preferably 0.1 μm or less. Further, as the insulating resin, it is desirable to use an electrically insulating transparent resin whose electrical resistance does not easily change due to changes in humidity or temperature. Examples of insulating resins include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polykene, and polycarbonate, and vinyl polymers such as polyvinylkene, borisdyrene, and polyacrylamide. It is preferably used in terms of film strength and chemical stability. It is desirable that the fine particles of the conductive metal oxide are dispersed in the insulating resin in an amount of 20% to 60% by weight. Below 20% by weight,
The electrical resistance was more than 10140 cm, and the
If it exceeds the maximum weight percentage, the film strength of the low-resistance surface protective layer will drop significantly. Therefore, dispersion is preferably carried out in a range of 30% to 50% by weight. In the electrophotographic photoreceptor of the present invention, the interface between the low-resistance surface protective layer and the charge generation layer needs to be a PI interface that stops charge injection. In order to form a charge injection/ejection interface, it is preferable to provide a charge injection blocking auxiliary layer between the low resistance surface protective layer and the charge generation layer. The materials for forming this auxiliary layer include coupling agents such as silane coupling agents and titanium coupling agents, organic zirconium compounds, and inorganic zirconium compounds.
Examples include organometallic compounds such as titanium compounds, and general-purpose resins such as polyester and polyvinyl butyral. The thickness of each layer in the electrophotographic photoreceptor of the present invention is 5 μm to 40 μm for the charge transport layer, preferably 8 μTr.
t~30μm is appropriate, and for the charge generation layer, 5μm.
m or less, preferably 0.1 μm to 3 μm, 0.5 μm to 20 μm for a low resistance surface protective layer, preferably 1 μm
m to 10 μm. EXAMPLES Hereinafter, the present invention will be explained by examples. Example 1 An electrophotographic photoreceptor was obtained by sequentially laminating a charge transport layer, a charge generation layer, and a low resistance surface protective layer having the following composition on a polyester film on which aluminum was vapor-deposited. Charge transport layer (film thickness 20μ) Polycarbonate resin 50 parts by weight (Teijin ■: Panlite) N,N'-diphenol-Nl-bis 50 parts by weight (3-methylphenyl) 41.1'-biphenyl] -4,4''-diamine charge generation layer (film thickness '1μ) Squaric acid derivative 30 parts by weight (structural formula (■)) Polyester resin 70 parts by weight (manufactured by Toyobo ■: Vylon-200) Low resistance surface protective layer ( Film thickness: 2μ) Tin oxide powder: 45 parts by weight Polyurethane resin (Kansai 48 parts by weight, manufactured by Paint: Retan Clear) Hardening agent: 7 parts by weight
+6kV using P428j Kawaguchi Electric La Seisakusho Co., Ltd.)
Measure the surface potential V DDP after being positively charged by corona discharge and leaving it in a dark place for 1 second, then expose it to white light, and measure the amount of light E1 required to reduce the surface potential (VODP) by half.
/2 was calculated. After this, 200 lux of light was applied to 0.
It was irradiated for 5 seconds, then roughly attenuated, and the residual potential RP was determined. This measurement was performed 1000 times in succession, and the 1st cycle and 1st cycle
000sf'ri/L, eyes (7) VDDP, RP(
7) Cycle stability was expressed as the difference ΔVDDp(c) and ΔRP(C). The measurement results are shown below. VDDP: 800V E1/2: 1, 3 Lux-5ecRP
: 60V △VDDP(C) (10℃, 20%) : 80VAR
P(C) (lo℃, 20%): 20V△VDDP(
C) (30°C, 80%): 60VARP(C) (30
'C, 80%): 20V From the above results, it can be seen that the electrophotographic photoreceptor of Example 1 has sufficient chargeability, high sensitivity, and excellent cycle stability. Example 2 In the combination of Example 1, an adhesive layer and a charge injection blocking auxiliary layer were newly provided with the following composition. Adhesive layer (film thickness 0.1μ) Polyester resin 100 parts by weight (Du
Made by Pont: Adhesive 49000) Charge injection blocking auxiliary layer (thickness 0.05μ) Organic zirconium compound
80 parts by weight (Matsumoto Pharmaceutical ■: ZA60) Silane coupling agent 20 parts by weight (Shin-Etsu Silicon ■: BH303) The obtained electrophotographic photoreceptor was measured in the same manner as in Example 1. The measurement results are shown below. yoop: 900V El/2: 1.3 Lux-sec RP: 80V ΔVDDP(C) (10℃, 20%): 60VARP(
C) (10℃, 20%): 20V△V DDP (
C) (30°C, 80%): 60V△RP(C) (3
0° C. 180%): 20 V From the above results, it can be seen that the electrophotographic photoreceptor of Example 2 has sufficient chargeability, high sensitivity, and excellent one-cycle stability. Comparative Example 1 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that β-type copper phthalocyanine was used instead of the squarine derivative in the charge generation layer, and measurements were performed in the same manner. The measurement results are shown below: VDDP: 500V E 1/2: 10 Lux -So(:RP
:60V △VD[)P(C) (10°Cl2O%):250VA
RP (C) (10'Cl2O%): 30VΔV
DDP(C) (30°C, 80%): 200VA
RP(C) (30°C, 80%): 50V From the above results, the electrophotographic photoreceptor of Comparative Example 1 had low chargeability;
It is also clear that there is a problem with cycle stability. Comparative Example 2 An electrophotographic photoreceptor was prepared in the same manner as in Example 2, except that β-type copper phthalocyanine was used instead of the squarine derivative in the charge generation layer, and measurements were performed in the same manner. The measurement results are shown below. VDDP Near 50V El/2: 11 Lux-5ecRP
:90V △V DDP(C) (10°Cl2O%):150V
ARP (C) (10'C, 20%): 30V△VD
DP (C) (30'C, 80%): 100VARP
(C) (30° C. 180%): 30 V From the above results, it can be seen that the electrophotographic photoreceptor of Comparative Example 2 had low chargeability and a problem in leak stability. Examples 3 to 5 Electrophotographic photoreceptors were prepared and measured in the same manner as in Example 2, except that the mixing ratio of the squarine derivative in the charge generation layer in Example 2 was changed as shown below. Ta. The measurement results are shown in Table 1. 16 One Example Charge Transport Layer 3 Squaric Acid Derivative/Polynisdel 1 et al. Old Information-50150 (Jewishube) 4
1 Tsukasa” 2
-/10/605
same"2
-20/80 Table 1 The above results show that the mixing ratio of squarine derivatives influences sensitivity and cycle stability. Example 6 An electrophotographic photoreceptor was obtained by sequentially laminating a charge transport layer, a charge generation layer, and a low-resistance surface protective layer having the following compositions on a polyester film on which aluminum was vapor-deposited. Charge transport layer (thickness 20μ) Polycarbonate resin 0 parts by weight - 17
= (Closed (Body made: Panlite L) N,N'-diphenyl-N,N'-bis(3-50 parts by weight medylphenyl)-[1,1°-biphenyl]-/1
．． 4"-Diamine charge generation layer (film thickness 1μ) Squaric acid derivative 30i parts (structural formula (II)) Polyester resin 70 parts by weight (Toyobo 0 wood: Vy10n-200) Low resistance surface protective layer (film thickness 2μ) Oxidation Tin powder: 45 parts by weight Polyester resin: 48 parts by weight (Nyretan Clear manufactured by Kansai Paint ■) Hardening agent: 7 parts by weight This electrophotographic photoreceptor was measured in the same manner as in Example 1.The measurement results is shown below: VDDP: 850V F1/2: 2.2 Luy, -secRP
Near 0V, A, VD[)P(C) (10'C, 20%): 80V
ARP (C) (10℃, 20%): 30V△V D
DP(C) (30℃, 80%): 70V△RP(
C) (30'C180%): 30V From the above results, the electrophotographic photoreceptor of Example 6 has sufficient chargeability and high sensitivity.
, and excellent cycle stability. Example 7 In the combination of Example 6, an adhesive layer and a charge injection positive auxiliary layer were newly provided with the following composition. Adhesive layer (film thickness 0.1μ) Polyester resin 100 parts by weight (D
o Made by Pont: Adhesive 49000) Charge injection blocking auxiliary layer (thickness 0.0!iμ) Organic zirconium compound 80 parts to 1 (60 parts by Matsumoto Seiyaku Aji) Silane coupling agent 20 parts by weight 4B (Shin-Etsu Siri-1) (Wood: KBH503) This electrophotographic photoreceptor was subjected to the same measurements as in Example 1. The measurement results obtained are shown below. VDDP: 1000V El/2: 2.3 Lux-5ecRP
:100V △V DDP(C) (10℃, 20%) Near 0VAR
P(C) (10℃, 20%): 30VΔV DDP
(C) (30℃, 80%) Near 0 VARP (C) (
30° C., 80%): 30V From the above results, it can be seen that the electrophotographic photoreceptor of Example 7 has sufficient chargeability, high sensitivity, and excellent cycle stability. Comparative Example 3 An electrophotographic photoreceptor was prepared in the same manner as in Example 6, except that β-type copper phthalocyanine was used instead of the squarine derivative in the charge generation layer, and measurements were performed in the same manner. The measurement results are shown below. VDDP: 500V 1mi1/2: 1Q Lux-secRP
:60V ΔV DDP(C) (10℃, 20%):250V-
20= ARP (C) (10'Cl2O%): 30V△
VI) DP(C) (30℃, 80%): 200V
△RP(C) (30℃, 80%): 50V'
From the above results, it can be seen that the electrophotographic photoreceptor of Comparative Example 3 has low chargeability and has problems with leakage and environmental stability. Comparative Example 4 An electrophotographic photoreceptor was prepared in the same manner as in Example 7 except that β-type copper phthalocyanine was used instead of the squarine derivative in the charge generation layer, and measurements were performed in the same manner. Each measurement value of Comparative Example 4 is shown below. VDDP Near 50V' El/2: l l Lux-5ecRP
:9C)V △V DDP(C) (10℃, 20%): 150VA
RP(C) (10°C, 20%): 30V△V
DDP (C) (30℃, 80%): 100VARP
(C) (30° C., 80%): 30 V From the above results, it can be seen that the electrophotographic photoreceptor of Comparative Example 4 had low chargeability and problems in cycle and environmental stability. Examples 8 to 10 Electrophotographic photoreceptors were prepared and measured in the same manner as in Example 7, except that the mixing ratio of the squarine derivative in the charge generation layer in Example 7 was changed as shown below. . The results are shown in Table 2. Example Charge transport layer 8 Squaric acid derivative/polyester resin-50150 (parts by weight) 9
Same as above =40/6010 Same as above
-20/80 Table 2 The above results show that the mixing ratio of squarine derivatives influences sensitivity and cycle stability. Example 11 A charge 1 transport layer, a charge I generation layer, and a low-resistance surface protective layer having the following composition were sequentially laminated on a polyester film on which aluminum had been vapor-deposited to form an electron-directed light body. . Charge transport layer (thickness 2() μ) Polycarbonate = i~Resin 55-layered parts (manufactured by Hitsuiri ■: Panrai 1-L) 4.4°-Benzylidene-45 parts by weight Bis(N, N'-Diedyl-m- Toluidine) Charge generation layer (film thickness 1μ) Squaric acid derivative 40 parts by weight (structural formula (■)) Polyester resin 60 parts by weight (Shubon, Adhesive 49000) Surface protective layer (film thickness 2μ)
) Tin oxide powder / 10-fold suspension urethane resin 60-overlap section
(manufactured by Kawaguchi Electric Seisakusho Co., Ltd.), the surface potential V DDP was measured using a +7 kV coroneau discharge, discharged for 1 second at the Did location, and illuminated with 5 lux tungsten light for 3 seconds. The amount of light [1/2] required to reduce V DDP by half was calculated. After that, 200 lux light was irradiated for 0.5 seconds, and the residual potential RP was determined by further attenuation1.This measurement was performed 1000 times in succession, and the VDDP of the 1st cycle and the 1000th cycle,
Cycle stability was expressed as RP (7) difference △1DP (C) and △RP (C). J: Measure the octopus at 10'0
．． It was carried out in an environment of 20% R1-1 and 30'C180% Rl-1, and one cycle [l)V DDP , RF)
(7) Environmental stability was expressed as the difference △VDDP (E) and △RP (E). The results are shown below. Table 3: It has sufficient chargeability, high sensitivity, and excellent 1-noise and environmental stability. Comparative Example 5 An electrophotographic photoreceptor was prepared in the same manner as in Example 11 except that β-type copper cap [l cyanine was used instead of the squarine derivative in the charge generation layer, and measurements were performed in the same manner. Results are not shown below. From the above results in Table 4, it can be seen that the electrophotographic photoreceptor of Comparative Example 5 had poor charging properties, and had problems in that cycle fluctuations and environmental fluctuations in V DDP were larger than those of Example 11. Comparative Example 6 An electrophotographic photoreceptor was prepared in the same manner as in Example 11, except that methylcellulose (1μ) was laminated and coated as a surface protective layer instead of the transparent surface protective layer. The results are shown below. Table 5 From the above results, the electrophotographic photoreceptor of Comparative Example 6 had poor charging properties, and the cycle fluctuations and environmental fluctuations of VDDP were similar to those of Example 11. Examples 12 to 16 A photoreceptor was prepared in the same manner as in Example 11, except that the charge transport layer in Example 11 was replaced with one of the following combinations. Example Charge transport layer 12ON, N'-Sifnyl N, N'-50 parts by weight bis(3-methylphenyl)-[1,1'-biphenyl]-4, 4'-Diamine○ Polycarbonate resin 50 parts by weight 1301-[
Pyridyl-(2)]-3-45 parts by weight (P-diethylaminostyryl) -5-(P-diethylaminophyl)pyrazoline Polycarbonate resin 55 parts by weight 1401-1
Quinolyl-(2)]-3-45 parts by weight (P-diethylaminobenzyl) -5-(p-diethylaminophenyl)pyrazoline Q polycarbonate resin 55 parts by weight 1504-diethylaminobenz 45 parts by weight Aldehyde-1,1
-Diphenylhydrazone○Polycarbonate 1~Resin 55 parts by weight 1602.
5-bis(/IN, N'-diethyl 50 parts by weight aminophenyl)-1,3,4 oxadiazole Polycarbonate resin 50 overlapping parts The measurement results are shown in Table 6. Table 6 Example 17 An electrophotographic photoreceptor was produced in the same manner as in Example 11 except that the surface protective layer in Example 11 was replaced with the following composition,
Measurements were taken. The measurement results are shown in Table 7. Surface protective layer tin oxide-antimony oxide solid solution 35 parts by weight Polyurethane resin 65 parts by weight Table 7 From the above results, the electrophotographic photoreceptors in Examples 12 to 17 were all sufficiently charged as in Example 11. Example 18 An adhesive layer having the following composition was formed on a poly]nidylene terephthalate film on which aluminum was vapor-deposited. charge transport layer,
A charge generation layer and a surface protection layer were sequentially spray coated to obtain an electrophotographic photoreceptor. Adhesive layer (thickness 0.005 μm) Polyester resin 5 parts by weight (manufactured by DuPont 49000) Tetrahydrofuran 80 parts Cyclohexanone 15 Heavy and small charge transport layer (
rPA thickness 20μ) Polycarbonate 5 parts by weight (
Yuto Panlite [) 1-Phenyl-3-(P-diethylamino 5 parts by weight Styryl-5-(P-diethylaminophenyl)pyrazoline Methylene chloride 30 parts by weight 1.1
．． 2-Trichloroethane 60 parts by weight Charge generation @ (film thickness 1 μm) Squaric acid derivative 4 parts by weight (Structural formula IV) Polyester resin 6 parts by weight (DuPont 49000) Methylene chloride 30 parts by weight 1.1
, 2-Trichloroethane 60 parts by weight Surface protective layer (film thickness 2 μm) Tin oxide 4 parts by weight Polyurethane resin 6 parts by weight (Kansai Paint Rethane 4000 Clear Base) tt2-Trichlorethane 60 parts by weight Methylene chloride 30 parts by weight The electrophotographic photoreceptor was tested using an electrostatic copying paper tester (product name: rSP42).
8J (manufactured by Kawanichi Denki Seisakusho Co., Ltd.), the surface potential V DDP was measured after being positively charged by 6.5 kV corona discharge and left in a dark place for 1 second, and then irradiated with 5 lux tungsten light for 3 seconds. During this time, the optical IE1/2 required for V DDP to be halved was determined. Roughly thereafter, light of 200 lux was irradiated for 0.5 seconds, and the residual potential RP was determined by immediately attenuating the light. This measurement was performed 1000 times in succession,
1st cycle and 1000th cycle Vl) DP,
Cycle stability was expressed as the difference in RP as ΔV DDP (C) and ARP (C). Also, this measurement was performed at 10'Cl2
Performed in an environment of O%RH and 30℃, 80%RH, the difference between the first cycle (7) VDDP and RP (7) was AVDDP.
(E), ARP (E) indicates environmental stability '1 no 1.3, measurement results are not shown below. VDDP: 930V El/2: 2.5 Lux-secRP
: 80V △Y DDP(C) : 100V ARP(C): 30V △VDDP(E) : 70V ARP(1':): 40V From the above results, the electrophotographic photoreceptor of Example 1B has sufficient charging property. It can be seen that it has high sensitivity, and excellent 1 noise and environmental stability. Comparative Example 7 An electrophotographic photoreceptor was prepared in the same manner as in Example 18, except that β-type copper phthalocyanine was used instead of the squarine derivative in the charge generation layer in Example 18, and measurements were performed in the same manner. The measurement results are shown below. VDDP: 600V Hi1/2: 10. 5 LUX-5ecR
P: 80V △VD[)P(C): 300V ARP(C): 30V △VDDP(E): 200V △RP(E): 50V From the above results, the electrophotographic photoreceptor of Comparative Example 7 was It can be seen that the stability is low, and there are problems with cycle and environmental stability. Comparative Example 8 An electrophotographic photoreceptor was prepared in the same manner as in Example 18, except that methyl cellulose (film thickness: 1 μm) was used instead of the squarine derivative in the charge generation layer.
When measurements were carried out in the same manner, the following measurement results were obtained. VDDP: 84. C) VEl/2: 1.1 +-UX-5ecRP
: 90V △VDDP(C) : 180V ARP(C): 50V △VDDP(E) : 310V ARP(E) near 0V From the above results, the electronic 77' true photoreceptor of Comparative Example 8 is particularly environmentally stable. It turns out that there is a problem with sexuality. Examples 19 to 21 Electrophotographic photoreceptors were prepared and measured in the same manner as in Example 18, except that the binder in the charge generation layer in Example 18 was replaced with one of the following combinations. Example Charge generation layer 19 Polyurethane (Nyrethane manufactured by Kansai Paint II 4
000 clear base) 20 Vinyl chloride = 33- (Kansai Paint ■: FPC-454) 21 Polyester (Kansai Paint 0 Vermilion: V-200) Table 8 From the above results, these electrophotographic photoreceptors: Example 1
As in No. 8, it can be seen that it has sufficient chargeability and high sensitivity, and that fluctuations due to cycles and environment are small. Examples 22 to 24 Electrophotographic photoreceptors were prepared in the same manner as in Example 18, except that the charge transport material C in Example 1B was replaced with the one below, and the measurements were carried out in the same manner. Example Charge transport material 22 2.5-bis(P-diethylaminophenyl)-
1,3,4-oxadiazole23 N,N'-diphenyl-N,N'-bis(3.
methylphenyl)-[1,1-biphenyl J-4,4°
-Diamine 24 4.4°-Benzylidene-bis(N,N'-diethyl-m-toluidine) Table 9 As is clear from the above results, these electrophotographic photoreceptors were similar to those in Example 18. It showed good electrical characteristics. Effects of the Invention Since the electrophotographic photoreceptor of the present invention has the above-described structure, the residual potential is low and uneven charging does not occur. Therefore, an image with uniform image density is also formed. Furthermore, since it has a low-resistance surface protective layer, there is no deterioration in electrophotographic properties even after repeated use.

[Brief explanation of the drawing]

1 to 4 are schematic diagrams of specific examples of the electrophotographic photoreceptor of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... Conductive support body, 2... Charge transport layer, 3...
Charge generation layer, 4... Low resistance surface protective layer, 5... Charge generation material, 6... Conductive metal oxide, 7... Adhesive layer, 8... Charge injection blocking auxiliary layer.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor in which a charge transport layer, a charge generation layer, and a low resistance surface protection layer are sequentially laminated on a conductive support, a squaric acid derivative is dispersed in the charge generation layer to generate charges. An electrophotographic photoreceptor characterized in that the interface between the layer and the low-resistance surface protective layer is a charge injection blocking interface.