JPH0313960A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity of a photosensitive body and to reduce deterioration of potential acceptance due to electrostatic fatigue by hardening a specified resin by cross-linking to form an undercoat layer. CONSTITUTION:This photosensitive body is obtained by successively laminating on a conductive substrate the undercoat layer, an electric charge generating layer, and a charge transfer layer and the undercoat layer is made of a binder resin (C) containing zirconium oxide particles (A) and tin oxide particles (B) both, preferably, treated with a silane coupling agent, such as a compound of formula I. The binder resin C can be prepared by cross-linking polyvinylacetal by a cyclic aliphatic isocyanate compound, such as 1,3-(isocyanatomethyl) cyclohexane and hardening it on the substrate.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer consisting of a substrate, an undercoat layer, a charge generation layer, and a charge transport layer, and particularly relates to This invention relates to an improved electrophotographic photoreceptor.

[Conventional technology]

Conventionally, photoreceptors used in electrophotography include those with a photoconductive layer mainly made of selenium or selenium alloys on a conductive support, and inorganic photoconductive materials such as zinc oxide and cadmium sulfide. Generally known are those that use organic photoconductive materials such as poly-N-vinylcarbazole and trinitrofluorenone or azo pigments, and those that use amorphous silicon-based materials. There is.

By the way, in general, the "electrophotographic method" means that a photoconductive photoreceptor is first charged in a dark place by, for example, corona discharge, and then imagewise exposed to selectively dissipate the charge only in the exposed area to create an electrostatic latent material. Image formation in which an image is obtained by obtaining an image, and developing and visualizing this latent image area with electrostatic fine particles (toner) made of coloring materials such as dyes and pigments and binders such as polymeric substances to form an image. It is one of the laws.

The basic characteristics required of the photoreceptor in such electrophotography are (1) the ability to be charged to an appropriate potential in a dark place;

(2) Less charge dissipation in the dark.

(3) Charge can be quickly dissipated by light irradiation.

Examples include.

In addition to these basic characteristics, each of the above-mentioned photoconductors has excellent features and disadvantages in practical use, but in recent years, photoconductors that have low manufacturing costs, little environmental pollution, and are relatively free have been developed. Organic photoreceptors are rapidly developing due to their ease of design.

In general, an organic photoreceptor is one in which a charge generating material and a charge transporting material are dispersed or dissolved in a binder resin and coated on a conductive support. Single layer type with charge transport function, charge generation layer (CGL) with charge generation function, charge retention and C
A charge transport layer (CTL) has the function of transporting charges injected from the GL, and further has functions such as blocking charge injection from the support or preventing light reflection on the support as necessary. A functionally separated type, which has a structure in which layers such as

Although these organic photoreceptors have excellent features as described above, they have the following drawbacks because they are organic materials.

(1) Low chargeability and charge retention.

(2) Fog and density unevenness occur on one image due to residual charge.

(3) Because the chemical, physical, and mechanical properties of the substrate are nonuniform, defects such as white spots and black spots occur on the image.

In particular, when a high-sensitivity photoreceptor is subjected to repeated charging and exposure, the characteristic (1) above appears as a significant deterioration due to so-called electrostatic fatigue. It is said that such fatigue occurs mainly because positive and/or negative charges remain in a movable state in the photoreceptor. In other words, due to repeated charging exposure, the remaining charges move to the surface at the start of the next charging operation and neutralize the charged charges.
The required rapid rise in surface potential at the initial stage of charging cannot be achieved.

For this reason, a desired surface potential cannot be obtained within the time set in the charging process, which poses a serious problem particularly in high-speed copying processes.

For the above-mentioned drawbacks, for example, Japanese Patent Application Laid-Open No. 47-6341.
Nos. 48-3544 and 48-12034 have cellulose nitrate resin intermediate layers, as disclosed in JP-A No. 48-47344.52.
-25638.58-30757.5g-63945,
58-95351, 58-98739 and 60-66
No. 258 has a nylon resin intermediate layer, which is disclosed in Japanese Patent Application Laid-Open No. 49-6
Nos. 9332 and 52-10138 disclose a maleic acid resin intermediate layer, and JP-A-58-105155 discloses a polyvinyl alcohol resin intermediate layer. In addition, intermediate layers containing various conductive additives in resin have been proposed in order to control the electrical resistance of the intermediate layer.
For example, JP-A No. 51-65942 uses an intermediate layer in which carbon or chalcogen-based substances are dispersed in a curable resin, and JP-A No. 52-82238 uses an isocyanate-based curing agent with the addition of a quaternary ammonium salt. JP-A-55-1180451 discloses a resin intermediate layer containing a resistance modifier, and JP-A-58-58556 discloses a resin intermediate layer in which aluminum or tin oxide is dispersed. ,
JP-A No. 58-93062 discloses a resin intermediate layer containing an organometallic compound;
Nos. 363 and 60-111255 have a resin intermediate layer in which conductive particles are dispersed, and JP-A-59-17557 has a layer in which magnetite is dispersed in a resin.
-84257, 59-93453 and 60-3205
No. 4 discloses a resin intermediate layer in which TiO2 and SnO2 powder are dispersed.

However, conventionally known electrophotographic photoreceptors are still insufficient in terms of deterioration in chargeability due to repeated use, particularly in terms of delay in the rise of the 4th charge, and furthermore, residual potential changes are large, which is still a major problem. Furthermore, many of the resins, inorganic particles, dyes, and other organic substances used in the intermediate layer are easily affected by temperature and humidity, to varying degrees, and as a result, the resistance value of the intermediate layer changes widely. . Even if an intermediate layer of a certain suitable material and film thickness is provided at room temperature, the electrostatic properties of the photoreceptor change significantly at low temperature and low humidity or high temperature and high temperature.

[Problem to be solved by the invention]

The present invention provides electrophotography that is highly sensitive, has a significantly small drop in chargeability due to electrostatic fatigue, and has a fast rise in charging potential and small change in residual potential even after repeated charging and exposure. Another object of the present invention is to provide an electrophotographic photoreceptor that has good charging properties and does not change its residual potential even under high temperature and low temperature conditions and low humidity.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive substrate, the undercoat layer is composed of zirconium oxide particles, tin oxide particles, and a binder resin. , and this binder resin blends a cycloaliphatic isocyanate compound and a polyvinyl acetal resin,
An electrophotographic photoreceptor is provided that is characterized by a binder resin that has been cured by a reaction.

The present inventor focused on the subbing layer of an electrophotographic photoreceptor, which is formed by sequentially laminating a subbing layer, a charge generation layer, and a charge transport layer on a conductive substrate, and conducted extensive studies to eliminate the above-mentioned drawbacks. result,
By making the components of the undercoat layer have the above-mentioned specific composition, an electrophotographic photoreceptor is provided that has a small delay in the rise of the 4th charge after repeated use, a small change in residual potential, and a small change in characteristics with respect to temperature and humidity. The present inventors have discovered that the following can be obtained, and have completed the present invention.

The present invention will be explained in detail below.

The zirconium oxide contained in the undercoat layer usually has a purity of 90% or more, preferably 99.5% or more. The tin oxide used usually has a purity of 90% or more, preferably 99.5% or more. Further, it is preferable that the average particle diameter of the primary particles of zirconium oxide and tin oxide is 0.5μ or less, preferably 0.3μ or less, and 0.5μ or less.
If it is more than 5 μm, roughness of characters, stains, etc. will be noticeable on the image, and the electrostatic characteristics will have large variations in sensitivity and poor quality stability.

In the present invention, the surfaces of the zirconium oxide and tin oxide are preferably treated with a silane coupling agent.

Such silane coupling agents include trimethylmonoethoxysilane, dimethyljethoxysilane, methyltrimethoxysilane, tetraethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, and β-(methacryloxypropyl). ) trimethoxysilane.

γ-glycidoxypropyltrimethoxysilane, β-(
Examples include 3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

To treat the surface of zirconium oxide using these silane coupling agents, 1. Usually, the silane coupling agent is applied in an appropriate solvent such as an aliphatic hydrocarbon such as n-hexane or an alcohol such as methanol or ethanol. It may be diluted, then mixed with dried zirconium oxide and tin oxide, filtered, washed and dried, and then subjected to a dispersion operation.

Various binder resins can be used.

Preferably, a polyacetal resin reaction-cured with an isocyanate compound is used.

The polyacetal resin used in the present invention generally includes polyvinyl acetal resins containing the following repeating units, and forms resins with different characteristics depending on the type of H.

Specific examples of this polyvinyl acetal resin include resins containing repeating units as shown below.

Furthermore, in the present invention, a polyvinyl butyral resin containing vinyl acetate and vinyl alcohol monomers at the same time in the seven-mer structure (4) is preferably used.

(n, Otori, n: integer) Normally 0 is 50JOmoQ%, ■ is 10moQ% or less,
It is preferable that n is 30 to 50@of1%.

In this way, in addition to at least one type of repeating unit selected from (1) to (5) above, the resin may contain two or more other repeating units to improve properties.

In this case as well, the resin must have OH groups present for the curing reaction, and the OH content is usually 1
=10 wt%, preferably 3-8 wt%. O
The H content is roughly considered from the following two points.

(1) An amount of O that can be cured to the extent that the undercoat layer does not dissolve in the solvent of the coating solution for the charge generation layer laminated on the undercoat layer.
Contains an H group.

(2) Contains an amount of OH groups that facilitates resin dispersion of zirconium oxide and tin oxide.

Examples of isocyanate compounds include cycloaliphatic diisocyanates such as 4,4'-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate, and 1,3-(isocyanate)cyclohexane, as well as adducts obtained by adding isocyanate compound monomers to polyols, such as An isocyanate compound having the following structure in which three molecules of isophorone diisocyanate are added to trimethylolpropane is also used.

Furthermore, isocyanurates in which three molecules of cycloaliphatic diisocyanate are polymerized can also be used.

Among these cycloaliphatic incyanate compounds, 1.3
Particular preference is given to using -(isocyanatomethyl)cyclohexane.

These isocyanate compounds undergo a thermal crosslinking reaction with a polymer compound containing 011 groups to form a cured coating film. In this case, it is necessary to add an amount (equivalent) of the isocyanate compound commensurate with the amount of OH groups.

However, zirconium oxide particles and tin oxide particles have
In some cases, a large amount of adsorbed water is contained and sufficient drying cannot be achieved by heat drying, or the solvent used in the coating solution may contain a small amount of water1.
Even if an equivalent amount of isocyanate compound is added to the resin, it will actually be insufficient. Therefore, the undercoat layer is cured with a large amount of uncrosslinked hydroxyl groups remaining, and as a result, the influence of temperature and humidity on the photoreceptor appears to be greater.

In this case, in the present invention, the amount of the isocyanate compound added is determined by the ratio of the number of NGO groups in the isocyanate compound to the number of OH groups in the polyacetal resin (NCOloH) of 1.
By setting it in the range of 71 to 571, preferably 1/1 to 3/1, stable charging performance is ensured even under fluctuations in temperature and humidity.

When the NGO1011 ratio is less than 1/1, the above problems are likely to occur, and when it is 5/1 or more, the good properties inherent to the polyacetal resin are lost.

The ratio by weight of the total amount of zirconium oxide particles and tin oxide particles to the binder resin is 1/1 to 19/l, preferably 3/1 to 10/1. If the ratio is less than 171, the effect will be small, and if it exceeds 19/1, air bubbles will remain in the undercoat layer, resulting in a difference between the charge generation layer and the charge transfer layer. ! & It is not preferable because it causes defects in the film.

The ratio of zirconium oxide particles to tin oxide particles used is 571 to 3071 by weight, preferably 9/1 to 20/2.
1°, more preferably 9/1-15/1.

The thickness of the undercoat layer is 0.3 to 10 .mu.m, preferably 0.5 to 5.0 .mu.m. When the thickness of the undercoat layer is less than 0.3μ.

It is not desirable to have a poor effect, and if it is 10μ or more, residual potential will accumulate.

In the present invention, in order to form the undercoat layer, a liquid in which the above components are dissolved or dispersed is applied onto the conductive substrate,
dry. Drying conditions are usually 80-tSO°C, 20 minutes-10 hours.

Examples of conductive substrates include metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, and platinum, and metal oxides such as tin oxide and indium oxide, which exhibit conductivity with a volume resistance of xallΩCm or less. A film or cylindrical plastic, paper, etc. coated by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, etc., and their adhesives, 1. ．． 1.1. It is possible to use pipes that have been made into blank pipes by methods such as , extrusion, and drawing, and then surface-treated by cutting, superfinishing, polishing, and the like.

Next, the charge generation layer will be explained.

The charge generation layer is a layer mainly composed of a charge generation substance, and a binder resin may be used as necessary.

Binder resins include polyamide, polyurethane,
Polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone,
Polystyrene, poly-N-vinylcarbazole, polyacrylamide, etc. are used.

Examples of charge-generating substances include CI Pigment Blue 25 (Color Index (CI) 21180).

CI Pigment Red 41 (CI 21200),
C.I. Acid Red 52 (CI 45100), C.I. Basic Red 3 (CI 45210), and a phthalocyanine pigment having a porphyrin skeleton,
Azulenium salt pigments, squalic salt pigments, azo pigments with a carbazole skeleton (described in JP-A-53-95033), azo pigments with a stilstilbene skeleton (
(described in JP-A No. 53-138229), azo pigments having a triphenylamine skeleton (described in JP-A-53-1325)
47), azo pigments having a dibenzothiophene skeleton (described in JP-A No. 54-21728), azo pigments having an oxadiazole skeleton (described in JP-A-54-1
2742), azo pigments having a fluorenone skeleton (described in JP-A-54-22834), azo pigments having a bisstilbene skeleton (described in JP-A-54-177)
33), an azo pigment having a distyryloxadiazole skeleton (described in JP-A No. 54-2129), an azo pigment having a distyrylcarbazole skeleton (described in JP-A-54-17734) , triazo pigments having a carbazole skeleton (described in JP-A-57-195767 and JP-A-57-195768), and CI Pigment Blue 16 (CI 74100).
Phthalocyanine pigments such as Sea Eye Butt Brown 5
(CI 73410).

Indigo pigments such as CI Bat Dye (CI 73030), Argo Scarlet B (manufactured by Violet),
Organic pigments such as perylene pigments such as Indus Thread Scarlet R (manufactured by Bayer AG) can be used.

Among these charge-generating substances, azo pigments are particularly preferred, and among azo pigments, disazo pigments and trisazo pigments shown below are most preferred.

Specific examples of azo pigments are shown below.

These charge generating substances may be used alone or in combination of two or more.

The binder resin is suitably used in an amount of 0 to 100 parts by weight, preferably 0 to 100 parts by weight, based on 100 parts by weight of the charge generating substance.
~50 parts by weight.

The charge generation layer contains a charge generation substance, along with a binder resin if necessary, tetrahydrofuran, cyclohexanone,
It can be formed by dispersing using a ball mill, attritor, sand mill, etc. using a solvent such as dioxane or dichloroethane, diluting the dispersion liquid appropriately, and applying the dispersion. Application can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transport layer consists of a charge transport substance and a binder resin used as necessary.

A charge transport layer can be formed by dissolving or dispersing the above-mentioned substances in a suitable solvent and applying and drying the solution.

Charge transport materials include hole transport materials and electron transport materials.

As hole transport substances, poly-N-vinylcarbazole and its derivatives, poly-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole Derivatives, imidazole derivatives, triphenylamine derivatives, 9-(p-diethylaminostyryl)anthracene, ■, 1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α- Examples include electron-donating substances such as phenylstilbene derivatives.

Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-dolinitro-9-fluorenone, 2,4,5.7-tetranitro-9-fluorenone, 2,4 , 5.7-tetranitroxanthone, 2,4°8-1-linitrothioxanthone, 2,6.8-trinitro-4)1-indeno(1,2-b)thiophene-
Examples include electron-accepting substances such as 4-one, 1,3.7-dolinitrodibenzothiophenone-5,5-dioxide.

These charge transport substances may be used alone or in a mixture of two or more.

Binder resins used as necessary in the present invention include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride- Vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone Examples include thermoplastic or thermosetting resins such as resins, epoxy resins, melamine resins, urethane resins, phenolic resins, and alkyd resins.

As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. are used.

The appropriate thickness of the charge transport layer is about 5 to 100 μm.

Further, in the present invention, a plasticizer or a leveling agent may be added to the charge transport layer.As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are. The appropriate amount to be used is 0 to 30'18% by weight relative to the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil are used, and the appropriate amount thereof is about 0 to 1 weight per weight of the binder resin.

In the present invention, it is also possible to further provide an insulating layer or a protective layer on the photosensitive layer.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example I The following subbing layer coating solution was dip coated on an AQ board and heated to 120°C.
This was dried for 30 minutes to form an undercoat layer containing zirconium oxide and tin oxide and having a thickness of 2.0.

[Subbing layer coating liquid]

525g of a 5.7% by weight cyclohexanone solution of butyral resin (S-LEC BL-1: Tanemizu Chemical Industry Co., Ltd.), 420g of zirconium oxide (Daiichi Kigenso Kogyo Co., Ltd.) surface-treated with a silane coupling agent according to the following recipe, and tin oxide. (manufactured by Mitsubishi Metals) 45g was
1 hard glass), filled with PSz balls (made of partially stable zirconia) to about half of the content, and dispersed in a ball mill for 100 hours.

(Surface treatment of zirconium oxide and tin oxide) 11, N
-C,H4-NH-C3H,-3i(OC11□)2(
2.0% by weight of Toshi Silicone IIKBM-602)
500 g of zirconium oxide particles (ZrO, -EP type) dried at 120° C. for 24 hours were mixed into the aqueous solution IQ and stirred. The filtrate was then filtered, and the filtrate was washed with a large amount of methanol, and then dried at 120° C. for 1 hour to obtain zirconium oxide surface-treated with a silane coupling agent. In addition, tin oxide surface-treated with a silane coupling agent was obtained using the same recipe.

146g of methyl ethyl ketone to 184g of this mill base
After dilution by adding 5.7 g of 1.3-(incyanate methyl)cyclohexane and
, 10 wt% cyclohexanone solution) was added,
The molar ratio of isocyanate groups and hydroxyl groups was 1.5:1 (NG
O10H=1.5/1), and the weight ratio of the total amount of zirconium oxide particles and tin oxide particles to the binder resin was 5=1.
A coating solution for the undercoat layer was prepared.

Next, on this subbing layer, the following charge generation layer coating solution was applied to Depping Coat L, and after drying at 120°C for 10 minutes, a charge generation layer having a thickness of 0.7 μm was formed.

(Charge generation layer coating liquid) Psz balls were put into a 15φ hardened glass pot to about half of the content, and then the azo pigment pot 3925 was added.
g and 415 g of cyclohexanone were charged. After 50 hours of ball milling, additional 560 g of cyclohexanone
was added and ball milled for 24 hours. Add cyclohexanone to this mill base and add about 2. A charge generation layer coating solution was prepared by diluting it to Ovt%.

Next, the charge transport layer coating solution shown below was applied by dipping coating on the charge generation layer and dried at 120° C. for 20 minutes.

A charge transport layer having a thickness of 20 μm was provided to obtain an electrophotographic photoreceptor of the present invention.

(Charge transport layer coating liquid) Charge transport material having the following structural formula: 20 g Tetrahydrofuran 160 g Example 2 In Example 1, zirconium oxide particles and tin oxide particles that were not surface-treated with a silane coupling agent were used, and an undercoat layer was used. The amount of millbase for the coating liquid was set to 221g.
The amount of methyl ethyl ketone is 129 g.

An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the amount of 1.3-(isocyanatomethyl)cyclohexane was changed to 8.6 g and the amount of butyral resin was changed to 20 g.

Example 3 In Example 1, KBM402) was used as a surface treatment agent for zirconium oxide and tin oxide particles, and the amount of mill base for the undercoat layer coating solution was 208 g, and the amount of methyl ethyl ketone was 1.
36g.

An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the amount of 1,3-(isocyanatomethyl)cyclohexane was changed to 6.5 g and the amount of butyral resin was changed to 35 g.

Example 4 In Example 1, the weight ratio of zirconium oxide and tin oxide in the mill base for coating the undercoat layer was changed from 9/1 to 5/1, and the surface treatment agent was used in the same manner as in Example 1, and electrophotography was carried out. A photoreceptor was produced.

Example 5 In Example 2, the weight ratio of zirconium oxide and tin oxide in the mill base for coating the undercoat layer was changed from 9/1 to 1571, and the surface treatment agent was used in the same manner as in Example 2, but electrophotographic photosensitive treatment was performed. The body was created.

Example 6 An electrophotographic photoreceptor was produced in the same manner as in Example 3 except that the surface treatment agent was changed from &39 to &1.

Comparative Example 1 An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that unsurface-treated zirconium oxide and tin oxide were used and the weight mixing ratio was changed from 971 to 4071.

Each electrophotographic photoreceptor produced as described above was tested using a commercially available electrostatic copying paper tester! (Kawaguchi Electric Seisakusho 5P-428), a corona discharge of -6 KV was performed for 20 seconds to charge the sample, and then the surface potential (v2) was measured 2 seconds after the start of charging. In addition, after charging for 20 seconds, the surface potential VR (residual potential) was measured after irradiation with a tungsten lamp at 2856° for 20Qux, then again at 180°.
After being charged to a surface potential of 0V, it was exposed to light using the tungsten lamp, and the exposure amount S required for the surface potential to attenuate to 1400V was measured.

Further, in order to determine the repeated fatigue characteristics, charging at 17 KV and exposure at 30 Qux were alternately repeated for 1 hour using the above apparatus, and Vz'*VR' and S' after fatigue were measured. The results are shown in Table-1.

Further, the electrophotographic photoreceptors of Examples 1 to 3 were made into a drum shape and used in a laser beam printer.

Installation, (30℃, 90%RH) and (15℃, 2
The image quality was evaluated by repeatedly subjecting the electrophotographic photoreceptor to fatigue by repeatedly printing 5,000 sheets in an environment of 0% RH). After continuous printing, a clear image with no deterioration similar to the initial image was obtained.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention is obtained by blending zirconium oxide particles and tin oxide particles, preferably surface-treated with a silane coupling agent, a cycloaliphatic isocyanate compound, and a polyacetal resin on a substrate, and curing the resultant mixture by reaction. By providing an undercoat layer made of a bonding resin, the film has remarkable characteristics such as high sensitivity, rapid rise of the 4-position charge, and small residual potential even after repeated charging and exposure.

Further, the electrophotographic photoreceptor of the present invention exhibits extremely small changes in electrical characteristics with respect to temperature and humidity.

Therefore, according to the electrophotographic photoreceptor of the present invention, it is possible to prevent abnormal images from occurring due to optical interference even in exposure using coherent light from a laser printer or the like.

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive substrate, the undercoat layer is composed of zirconium oxide particles, tin oxide particles, and a binder resin; An electrophotographic photoreceptor characterized in that the binder resin is a binder resin that is a mixture of a cycloaliphatic isocyanate compound and a polyvinyl acetal resin and is cured by reaction. (2) The electrophotographic photoreceptor according to claim (1), wherein the zirconium oxide particles and the tin oxide particles are surface-treated with a silin coupling agent.