JPH0313957A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and speed of potential rising and to reduce change of residual potential of a photosensitive body even in repeating cycles of electric charging and exposure to light by forming an undercoat layer of specified 2 kinds of oxide particles and a resin. 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 composed of zirconium oxide particles and tin oxide particles both surface treated with an organic titanium compound, such as a compound of formula I, and a binder resin, and it can be formed by mixing a polyetherpolyol resin with an aromatic isocyanate compound as its cross-linking agent, such as tolylene-2,4-diisocyanate in a prescribed ratio, and adding both the surface treated to prepare a coating solution, coating the substrate with it, and hardening it by heating.

Description

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

[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, for example, by corona discharge, and then imagewise exposed, and the charge in the exposed area is selectively dissipated to create an electrostatic latent. 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 transport function, charge generation layer (CGL) with charge generation function, charge retention and CG
A charge transport layer having a function of transporting charges injected from L (
CTL), and a functionally separated type that has a laminated layer with functions such as blocking charge injection from the support or preventing light reflection on the support as necessary. It is being

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. Such fatigue is said to occur 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 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 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 TiO□, SnO, and 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 normal temperature and normal humidity, the electrostatic properties of the photoreceptor change significantly at low temperature and low humidity or high temperature and high humidity.

[Problem to be solved by the invention]

The present invention provides electrophotography that is highly sensitive, has a significantly small decrease 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 high humidity conditions and under low temperature and low humidity conditions.

[Means to solve the problem]

According to the present invention, in an electrophotographic photoreceptor in which a subbing 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 and tin oxide particles whose surface has been treated with an organic titanium compound, and a binder resin. Preferably, the binder resin contains a polyether polyol resin, an aromatic isocyanate compound, an isocyanate group, and a hydroxyl group. The ratio of numbers is from 1:1 to 3=1,
An electrophotographic photoreceptor is provided that is characterized by a reaction-cured binder resin.

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.

Hereinafter, one aspect of the present invention will be explained in detail.

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 is usually one with a purity of 90% or more, preferably one with a purity of 99.5% or more.

In addition, the average particle size of the primary particles of zirconium oxide and tin oxide is preferably 0.5μ or less, preferably 0.3μ or less. etc. are noticeable, and the electrostatic characteristics have large variations in sensitivity and poor quality stability.

In the present invention, an organic titanium compound is used as the surface treatment agent for zirconium oxide and tin oxide.

Organic titanium compounds usually have the general formula (■).

At least one kind of compound represented by general formula (n) and general formula (m) is used.

(In general formulas (1) and (II), OR,, OR□,
OR and OR4 represent an alkoxy group, a carbalkoxy group, a phenoxy group, a sulfoxy group, and a phosphoxy group, n represents an integer of 0 or 1 or more) Ti(L
)nL-n (m) (general formula (
In m), L is a chelate group, X is an ester group, and n is 1
-4 integer) Examples of the compound represented by the general formula (I) include tetramethyl orthotitanate, tetraethyl orthotitanate, tetra-n-propyl orthotitanate, tetracresyl titanate, tetrabutyl orthotitanate, and tetraisobutyl Ortho titanate, tetracresyl titanate, tetrastearyl titanate, tetra-2
-ethylhexyl titanate, isopropyltriisostearyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl-tris(dioctylpyrophosphate) titanate, and the like.

Examples of the compound represented by general formula (II) include:
Examples include tetrabutyl polytitanate, tetracresyl polytitanate, and tetraacetylacetonate polytitanate.

Examples of the compound represented by the general formula (Tll) include diisopropoxytitanium-bis-octanediol, diisopropoxytitanium-bis-hexanediol, diisopropoxytitanium-bis(acetylacetonate), titanium tetralactate ethyl Examples include ester, tetratriethanolamine titanium chelate, and the like.

Other titanium compounds include titanium tetraammonium lactate, titanium tetraacetylacetonate ammonium lactate, tetraisopropyl-bis(dioctylphosphate) titanate, tetraoctyl-bis(ditridecylphosphate) titanate, and tetra(2) ,2-diaryloxymethyl-1-butyl)bis(tidolidecyl phosphate)
In addition to titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, tris(dioctyl pyrophosphate) ethylene titanate, the following titanium compounds may also be mentioned.

Isopropyl tris isostearoyl titanate, isopropyl tris (dioctyl pyrophosphate), isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra (2,2'-diallyloxymethyl-1) -butyl)bis(ditridecyl)phosphite titanate, bis(dioctylpyrophosphate)
Oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, isopropyl dimethacrylylisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl trictinate Milphenyl titanate, tetraisopropylbis (
dioctyl phosphite) titanate, etc.

These organotitanium compounds are usually used to treat zirconium oxide and tin oxide surfaces.

The organic titanium compound may be diluted with a suitable solvent such as n-hexane or an alcohol, and then mixed with dried zirconium oxide and tin oxide, filtered, washed, dried, and subjected to a dispersion operation.

(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.

An aromatic isocyanate compound is used for curing the binder resin. Such aromatic isocyanate compounds include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene isocyanate, metaxylylene diisocyanate, 3,3'-bistrylene-4,4'-diisocyanate, 3. 3'
- of aromatic or aromatic polyisocyanate monomers or isocyanate compounds such as dimethyldiphenylmethane 4,4'-diisocyanate, naphthalene-1,5-diisocyanate, triphenylmethane triisocyanate, tris-(P-isocyanatophenyl)thiophosphite, etc. Examples include isocyanate adducts in which monomers are added to polyols. For example, adducts with the following structure in which three molecules of tolylene diisocyanate are added to trimethylolpropane, and isocyanurates in which three molecules of diisocyanate monomer are reacted. can give.

These isocyanate compounds undergo a thermal crosslinking reaction with a polymeric compound containing an OH group 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 may be contained and sufficient drying cannot be achieved by heat drying, or the solvent used in the coating solution may contain a small amount of water, causing Even if an equivalent amount of isocyanate compound is added, it will actually be insufficient. For this reason, 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 addition of an isocyanate compound is The amount is determined by the ratio of the number of NGO groups in the isocyanate compound to the number of OH groups in the polyether polyol resin (NGOl
oH) is 1/1-3/1, preferably 1.3/1-2
．． By setting it in the range of 2/1, stable charging performance is ensured even against fluctuations in temperature and humidity.

When the NGO10H ratio is less than 1/1, the above problems are likely to occur, and when it is 3/1 or more, the good properties inherent to the polyether polyol resin are lost.

The weight ratio of the zirconium oxide particles and tin oxide to the binder resin is 50,150 to 9,575, preferably 371 to 10/1.
If it is less than 9515, the effect will be small, and if it exceeds 9515, air bubbles will remain in the undercoat layer, causing defects in the charge generation layer and charge transfer layer coatings, which is not preferred.

The thickness of the undercoat layer is 0.3 to 10 .mu.m, preferably 0.5 to 5.0 .mu.m. If the thickness of the undercoat layer is less than 0.3 μm, the effect will be poor, and if it is more than 10 μm, residual potential will accumulate, which is not desirable.

The weight ratio of zirconium oxide to tin oxide is 571 to 3071, preferably 971 to 30/1. More preferably, it is 971-1571.

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 80-150℃, 20
minutes to 10 hours.

Examples of conductive substrates include those exhibiting conductivity with a volume resistance of 101 oΩcm or less.1For example, metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, and platinum, and metal oxides such as tin oxide and indium oxide. Film-like or cylindrical plastic, paper, etc. coated by vapor deposition or sputtering, or plates of aluminum, aluminum alloy, nickel, stainless steel, etc., and their coatings; 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) , a triazo pigment having a carbazole skeleton (JP-A-57-195767).

57-195768), phthalocyanine pigments such as CI Pigment Blue 16 (CI 74100), CI Bat Brown 5 (CI
73410), CI 7303
Organic pigments such as indigo pigments such as 0) and perylene pigments such as Argo Scarlet B (manufactured by Violet) and Indus Thread Scarlet R (manufactured by Bayer) 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.

face” calculation Specific examples of azo pigments are shown below.

Face 4 Rainbow Shame 1 1 1 1 Face J Rainbow Ugly Face "L and f Face" 1 Enthusiastic Face J [Chest 1 11 Δ--- --- Δ-11 Face JLNG Face" Rainbow- 11 1 to 111 face 41 and face J rainbow b -- 1 to 111 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/Jl, preferably about 0.1 to 2.

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.

Examples of the hole transport substance include poly-N-vinylcarbazole and its derivatives, poly-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, 'polyvinylphenanthrene, oxazole derivatives, and oxazole derivatives. Azole derivatives, imidazole derivatives, triphenylamine derivatives, 9-(P-diethylaminostyryl)anthracene, l,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
-trinidrothioxanthone, 2,6.8-trinitro-4H-indeno(1,2-b)thiophen-4-one, 1,3.7-dolinitrodibenzothiophenone-5,5-dioxide, etc. Examples include electron-accepting substances.

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 thickness of the charge transport layer is suitably about 5 to 100 mm.

Further, in the present invention, a plasticizer or a leveling agent may be added to the charge transport layer.

Those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 to 30% based on the binder resin.
Approximately % by weight is appropriate. 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% by weight based on 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 1 The following subbing layer coating solution was dip-coated on an Al1 plate, and
It was dried at .degree. C. for 30 minutes to form an undercoat layer containing zirconium oxide and tin oxide and having a thickness of 2.0 IJs.

[Subbing layer coating liquid]

530 g of polyether polyol (GP-1000: Sanyo Kasei Co., Ltd.) 7.71#t% solution (cellosolve acetate: methyl isobutyl ketone = 1:1) and oxidized surface treated with a titanium-based force-offering agent according to the following formulation. 400 g of zirconium (EP type: Daiichi Kigensho Kogyo M) and 50 g of tin oxide (S-1: Mitsubishi Metals Co., Ltd. 11) were mixed and placed in a glass ball mill pot (15 φ cm made of hard glass).

Dispersion was performed using a 100-hour leap ball mill using a PSZ ball.

(Surface treatment of zirconium oxide and tin oxide) (Plenact KR-TTS: manufactured by Ajinomoto Co., Inc.) 2. Owt% n-hexane solution IQ was mixed with 500 g of zirconium oxide dried at 120°C for 24 hours at a weight ratio of 100:30, stirred, and surface-treated. After washing with.

It was dried at 120° C. for 1 hour to obtain zirconium oxide surface-treated with a titanium coupling agent. The surface treatment of tin oxide was carried out in exactly the same manner.

After diluting 150 g of solvent (cellosolve oxide/methyl isobutyl ketone) to 173 g of this millbase, 5.6 g of tolylene-2,4-diisocyanate and 71 g of polyether polyol (GP-1000 10% solution) were added to NGOloH (moQ ratio). )='1.5/l, total weight of zirconium oxide and tin oxide and weight ratio of binder resin 4
:1 to prepare an undercoat layer coating solution.

Next, the following charge generation layer coating solution was applied by seed coating on the undercoat layer, and after drying at 120 DEG C. for 10 minutes, a charge generation layer having a thickness of 0.5 mm was formed.

(Charge generation layer coating liquid) PSz balls were put into a 15φl hardened glass pot to about half of the content, and then 3925 g of the above azo pigment was added.
Then, 415 g of cyclohexanone was added. After ball milling for 50 hours, 560 g of cyclohexanone was further added and ball milling was carried out for 24 hours. Cyclohexanone was added to this mill base to dilute it to about 2.0 wt % to prepare a charge generation layer coating solution.

Next, the charge transfer layer coating solution shown below was coated on the charge generation layer by dipping, and dried at 120°C for 20 minutes to form a film with a thickness of 20°C.
．． A charge transport layer was provided to obtain an electrophotographic photoreceptor of the present invention.

(Charge transport layer coating liquid) Charge transport material having the following structural formula 20g Tetrahydrofuran 160g Example 2 In Example 1, the amount of the millbase for the subbing layer coating liquid was changed to 1
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 97 g of the diluent, 142 g of the diluting solvent, 5.0 g of tolylene 2,4-diisocyanate, and 48 g of polyether polyol (1 part solution) were used.

Example 3 In Example 1, the following surface treatment agent was used as the surface treatment agent for the zirconium oxide particles and the tin oxide particles. The amount of diluting solvent was 134 g, the amount of tolylene-2,4-diisocyanate was 4.6 g, and the amount of polyether polyol solution was 29 g.
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that g was used instead.

Example 4 In Example 1, the mixing ratio of zirconium oxide and tin oxide was changed to 6:1, and the amount of mill base for the undercoat layer coating solution was 225 g, the amount of diluting solvent was 130 g, trilene-2,
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that the amount of 4-diisocyanate was changed to 5.9 g and the amount of polyether polyol solution was changed to 19.6 g.

Example 5 In Example 1, the mixing ratio of zirconium oxide and tin oxide was changed to 12:1, and the amount of mill base for the undercoat layer coating solution was 239 g, the diluent solvent was 122 g, and )-rylene-
8.0 g of 2,4-diisocyanate, 3.3 g of solution
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that .

Example 6 In Example 1, the azo pigment as the charge generating material was replaced with Nn.
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that &1 was substituted from No. 39 and the surface treatment agent was replaced with the following.

(Plenact KR-1388: manufactured by Ajinomoto Co., Ltd.) Comparative Example 1 In Example 1, unsurface-treated zirconium oxide and tin oxide were used, and the mixing ratio was changed to 40:1, and
The amount of millbase for the undercoat layer coating solution was 207 g, and the amount of tolylene-2,4-diisocyanate was 2.9 g.

An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that 40 g of the polyether polyol solution was used.

Each of the electrophotographic photoreceptors produced as described above was charged by performing -6KV corona discharge for 20 seconds using a commercially available electrostatic copying paper tester (Kawaguchi Electric Seisakusho 5P-428), and the surface of the photoreceptor was charged. After measuring the potential 9 and leaving it in the dark for another 20 seconds, the surface potential V was measured.Then, tungsten lamp light was irradiated so that the illuminance on the photoreceptor surface was 45Qx until vo reached 172. exposure amount E1/2 and 3
After 0 seconds, the residual potential Vr was measured.

In addition, in order to know the repeated fatigue characteristics, -7,5
Charging with KV and exposure with 30 lux were repeated for 1 hour to obtain the surface potential after fatigue v'11 surface potential V'o, exposure amount E
'1/2 and residual surface potential V'r were measured.

Further, the electrophotographic photoreceptors of Example 2 and Example 3 in the form of a drum were attached to a laser beam printer (30°C, 90% RH), (15°C, 20% RH).
), the electrophotographic photoreceptor was repeatedly subjected to fatigue by repeatedly printing 500 sheets, and the quality of one image was evaluated. After continuous printing, a clear image with no deterioration comparable to the initial image was obtained.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention comprises a substrate, zirconium oxide and tin oxide surface-treated with an organic titanium compound, and a binder resin, preferably an aromatic isocyanate compound.
By providing an undercoat layer using a polyether polyol resin as a binding material, which is reaction-cured with a GOlo)I ratio of 1/1 to 3/1, it has high sensitivity and remains strong even after repeated charging exposure. , it has the remarkable characteristics that the charge at the 4th position rises quickly and the residual potential is small.

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 light 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 and tin oxide particles whose surface has been treated with an organic titanium compound. A photoreceptor for electrophotography characterized by being made of a resin-adhesive resin. (2) The binder resin is a polyether polyol resin. 1. A photoreceptor for electrophotography, which is a binder resin containing an aromatic isocyanate compound in a ratio of isocyanate groups to hydroxyl groups in a ratio of 1:1 to 3:1 and cured by reaction.