JPH0313959A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity of a photosensitive body and the speed of potential rising even in repeating cycles of electric charging and exposure to light and to reduce change of residual potential by forming an undercoat layer made of specified 2 kinds of compound particles. 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 containing both of zirconium oxide and tin oxide particles surface treated with a fluorinated surface treating agent, such as formula I. It is preferred to mix aliphatic isocyanate with polyvinylacetal as the binder resin, to coat the substrate with the mixture, and to dry and harden it. A desired trisazo pigment can be used as a charge generating material and a compound of formula II and the like can be used as a charge transfer material.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a conductive substrate, an undercoat layer, and a charge generation layer.

The present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer comprising a charge transport layer, and particularly to an electrophotographic photoreceptor having an improved subbing layer.

[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. An image is obtained, and this latent image area is developed and visualized with electrostatic fine particles (toner) composed of coloring materials such as dyes and pigments and binders such as polymeric substances to form an image. This is one of the formation methods.

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 a material 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) Residual charge causes fog and density unevenness on the image.

(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 rapid rise in surface potential required at the initial stage of IF electrolysis 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.
-25638.58-30757.58-63945.
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 layer1.
For example, JP-A-51-65942 discloses an intermediate layer in which carbon or chalcogen-based substances are dispersed in a curable resin.
JP-A-52-82238 discloses a thermal polymer intermediate layer using an isocyanate curing agent with the addition of a quaternary ammonium salt, and JP-A-55-1180451 discloses a resin intermediate layer containing a resistance modifier. , JP-A-58-58556 discloses a resin intermediate layer in which aluminum or tin oxide is dispersed, and JP-A-58-93062 discloses a resin intermediate layer in which an organometallic compound is added. .60-9
Nos. 7363 and 60-111255 have a resin intermediate layer in which conductive particles are dispersed, and JP-A-59-17557 has an eyebrow in which magnetite is dispersed in a resin.
9-84257.59-93453 and 60-320
No. 54 discloses a resin intermediate layer in which Tie and SnO□ 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 made of a suitable material and having a certain 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 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 an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive substrate,
There is provided an electrophotographic photoreceptor characterized in that the undercoat layer comprises zirconium oxide particles and tin oxide particles whose surface has been treated with a fluorine-based surface treatment agent, and a 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-described specific composition, there is little delay in the rise of the electrification after repeated use.
The inventors have also discovered that an electrophotographic photoreceptor can be obtained that exhibits small changes in residual potential and small changes in characteristics with respect to temperature and humidity.

The present invention has now been completed.

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. As the tin oxide, one with a purity of 90% or higher, preferably 99.5% or higher is used.

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, the surfaces of the zirconium oxide and tin oxide are treated with a fluorine-based surface treatment agent.

As the fluorine-based surface treatment agent, those having the following structural formula are usually used.

CnF,-,Q(,-GE,-ωO1((rs44)C
nF2n+1-Gl=C)1. (n=(y-12)C
IIF17C1(,-CH□IH swordI fraud H8C, Fl
,-CI! , -CI, -OH Although various binder resins can be used, polyvinyl acetal resin reaction-cured with an isocyanate compound is preferably used.

The polyvinyl atal resin used in the present invention generally contains the following repeating units, and R
Forms resins with different characteristics depending on the type.

C,F,,C0-0-C,H,-5i(QC)I))I
Cm Fl□-so, -N-C2 horse-5i ((9),)
3-ke CIFI-1ωIIJH-C3H-3i (OCHs)i
To treat the surfaces of zirconium oxide and tin oxide using these surface treatment agents, 1. Usually, the surface treatment agent is treated with an appropriate solvent such as a saturated aliphatic hydrocarbon such as n-hexane, or an alcohol such as methanol or ethanol. is diluted, and then mixed with dried zirconium oxide and tin oxide, filtered, washed and dried, and then subjected to a dispersion operation.

(R: Alkyl group or hydrogen) 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 simultaneously in the monomer composition (4) is preferably used as described below.

(Q, ■, n: integer) Generally, it is preferable that Ω is 50 to 80−0Q%, Ω is 10 mofi% or less, and n is 30 to 50 moQ%.

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 to 1.
It is 10 wt%, preferably 3 to 8 vt%. OH
The content rate 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 particles and tin oxide particles.

An aliphatic isocyanate compound is used for curing the binder resin. Examples of such aliphatic isocyanate compounds include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine isocyanate, and the like. Further, in the present invention, an isocyanate adduct obtained by adding an isocyanate compound monomer to a polyol can also be used.

As such an incyanate adduct body.

For example, an adduct with the following structure in which three molecules of hexamethylene diisocyanate are added to trimethylolpropane, a biuret made by reacting hexamethylene diisocyanate with water, an isocyanurate made by polymerizing three molecules of aliphatic isocyanate monomer, etc. .

Examples include the following structure in which three molecules of hexamethylene diisocyanate are polymerized.

These isocyanate compounds undergo a thermal crosslinking reaction with a polymer compound containing an OH group to form a cured coating. In this case, the amount ( equivalent amount) of isocyanate compound should be added.

However, zirconium oxide particles and tin oxide particles have
In some cases, a large amount of adsorbed water may be contained and sufficient drying may not be achieved by heat drying, or the solvent used in the coating solution may contain a small amount of water.
Even if an equivalent amount of isocyanate compound is added to I fat, 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 1 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 O1l groups in the polyacetal resin (NGOloH).
By setting it in the range of 1/1 to 3/l, preferably 1.2/1 to 2.2/1, it is stable against fluctuations in temperature and humidity.
iF conductivity is ensured.

If the NGO10H ratio is less than 171, the above problems are likely to occur. If it is 3/1 or more, the good properties inherent to the polyacetal resin are lost.

The ratio of the total amount of zirconium oxide particles and tin oxide particles to the binder resin used is 50,150 to 9,515 degrees, preferably 3/1 to 10/1, in a weight ratio of 5. Usage rate is 5015
If it is less than 0, the effect will be small, and if it exceeds 9515, air bubbles will remain in the undercoat layer, resulting in defects in the charge generation layer and charge transfer layer coatings, which is not preferred.

The thickness of the undercoat layer is 0.3-10μ, preferably 0.
It is 5 to 5.0μ. 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.

Further, the ratio of zirconium oxide particles to tin oxide particles used is 5/1 to 30/l in weight ratio, preferably 9/1 to 20/1.
More preferably, it is 971 to 15/1.

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 to 150°C and 20 minutes to 10 hours.

As the conductive substrate, materials exhibiting conductivity of 1 volume resistivity of 101 oΩcya or less, such as aluminum, nickel,
Metals such as chromium, nichrome, copper, silver, gold, and platinum, and metal oxides such as tin oxide and indium oxide are coated on film or cylindrical plastics, paper, etc. by vapor deposition or sputtering, or aluminum. , plates of 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 C.I. Pigment Blue 25 [Color Index ((1:I) 21180
], CI Pigment Red 41 (CI 21200
), Sea Eye Acid Red 52 (CI 45100)
, CI Basic Red 3 (CI 45210),
Furthermore, phthalocyanine pigments having a porphyrin skeleton, azulenium salt pigments, squalic salt pigments, and azo pigments having a carbazole skeleton (Japanese Patent Application Laid-Open No. 53-95033
(described in JP-A-53-138229), an azo pigment having a stilstilbene skeleton (described in JP-A-53-138229), an azo pigment having a triphenylamine skeleton (described in JP-A-53-13-13)
2547), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728)
, an azo pigment having an oxadiazole skeleton (Japanese Unexamined Patent Application Publication No. 54
-12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-22834),
Azo pigment having a bisstilbene skeleton (JP-A-54-1
7733), an azo pigment having a distyryloxadiazole skeleton (described in JP-A-54-2129), an azo pigment having a distyrylcarbazole skeleton (described in JP-A-54-17734) , a triazo pigment having a carbazole skeleton (Japanese Patent Application Laid-Open No. 57-19576
No. 7, No. 57-195768), and CI Pigment Blue 16 (CI 7410).
0) and other phthalocyanine pigments such as CI 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.

N.

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

It is appropriate to use the binder resin in an amount of 0 to 100 parts by weight based on 100 parts by weight of the charge generating substance, and preferably θ
-50 parts by weight.

The charge generation layer contains a charge generation substance, along with A inder 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 0. A value of about 01-5 is appropriate, and preferably 061-2.

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.

As hole transport substances, poly-N-vinylcarbazole and its derivatives, poly-γ-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, l,1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α - Electron-donating substances such as phenylstilbene derivatives can be mentioned.

Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4.7-trinitro-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)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 rubber), acrylic resin , thermoplastic or thermosetting resins such as silicone 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 tones.

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 about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil are used, and the appropriate amount is about 0-1 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 Dip coat the following subbing layer coating solution on the Aj2 board.

It was dried at 120 DEG C. for 30 minutes to form an undercoat layer containing zirconium oxide and tin oxide and having a thickness of 2.0.

[Undercoat layer coating liquid]

Oxidation with 525 g of a 5.7 weight 2-cyclohexanone solution of butyral resin (S-LEC BL-1: Tanemizu Chemical Industry Co., Ltd.) and 420 g of zirconium oxide (manufactured by Daiichi Kigenso Kogyo Co., Ltd.) surface-treated with a fluorine-based surface treatment agent according to the following recipe. Tin (manufactured by Mitsubishi Metals) was placed in a ball mill bot (15φ1 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) C, FL,
, C00C,H,5i(OCH,), 500g of zirconium oxide particles (ZrO, -HP type) dried at 120°C for 24 hours were mixed into 1Ω of a 2.0% by weight methanol solution and stirred. Next, this liquid was 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 fluorine-based surface treatment agent. Surface-treated tin oxide was obtained using a completely similar recipe.

125g of methyl ethyl ketone to 129g of this millbase
After diluting by adding hexamethylene diisocyanate 4.
5 g and 67 g of butyral resin liquid (BL-1, 10 wt% cyclohexanone solution) were added to make the molar ratio of incyanate groups and hydroxyl groups to 1.5:1 (NGO10H = 1.5
/1) and the weight ratio of the total amount of zirconium oxide particles and tin oxide to the binder resin was adjusted to 5:1 to prepare an undercoat layer coating solution.

Next, on this undercoat layer, the following charge generation layer coating solution was applied by dipping coating, 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 up to about half of the content, and then the azo pigment Nα3925 was added to the pot.
g and 415 g of cyclohexanone were 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 60g Example 2 In Example 1, the amount of mill base for the undercoat layer coating liquid was 157g, the amount of methyl ethyl ketone was 115g, and hexamethylene diisocyanate. An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the amount of the butyral resin was changed to 3.7 g and the amount of the butyral resin was changed to 39 g.

Example 3 In Example 1, zirconium oxide and oxide (manufactured by Mitsubishi Metals) were used, and the amount of millbase for the undercoat layer coating solution was 151'1 g, the amount of methyl ethyl ketone was 115 g, and the amount of hexamethylene diisocyanate was An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the amount of butyral resin was changed to 3.7 g and 38 g.

Example 4 In Example 1, the azo pigment which is the charge generating material was replaced with Na
39 to Nal, and the surface treatment agents of zirconium oxide and tin oxide were replaced with C, Fl, -C□H, -COOH, and in addition, in preparing the mill base for the undercoat layer coating solution, zirconium oxide and tin oxide were used. ratio from 971 to 67
A coating solution was prepared in the same manner as in Example 1, except that subbing layer coating solution 161 g of mill base, 110 g of methyl ethyl ketone, 5.2 g of hexamethylene diisocyanate, and 44 g of butyral resin solution were used. An electrophotographic photoreceptor was prepared.

Example 5 In Example 2, the azo pigment as the charge generating material was used as No. 39.
In addition, the surface treatment agents of zirconium oxide and tin oxide were replaced with C, F□, -C,H, -COOH, and in addition, zirconium oxide and tin oxide The ratio of 971 to 1271
A coating solution was prepared in the same manner as in Example 2, except that 161 g of the mill base for the undercoat layer coating solution, 110 g of methyl ethyl ketone, 7.0 g of hexamethylene diisocyanate, and 33 g of the butyral resin solution were used to prepare the coating solution. An electrophotographic photoreceptor was prepared.

Example 6 In Example 3, the azo pigment as the charge generating material was used as No. 39.
Same as Example 3, except that Nol was replaced with Nol, zirconium oxide and acid were replaced, and the mill base for the undercoat layer coating solution was replaced with 122 g, methyl ethyl ketone was replaced with 128 g, hexamethylene diisocyanate was replaced with 3.2 g, and butyral resin was replaced with 75 g. An electrophotographic photoreceptor was prepared.

Comparative Example 1 Using 0 in Example 1, normal zirconium oxide and tin oxide particles that have not been surface treated with a fluorine-based surface treatment agent, 122 g of mill base for the undercoat layer coating solution, 128 g of methyl ethyl ketone, and 3 hexamethylene diisocyanate. An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the butyral resin was replaced with 74.5 g.

Each of the electrophotographic photoreceptors prepared 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. The potential V was measured, and after being left in a dark place for 20 seconds, the surface potential Vo was measured.

Next, the tungsten lamp light was applied to the surface of the photoreceptor at an illuminance of 4.5! The exposure amount E1/2 until vO became 1/2 after irradiation was applied so that the voltage was ux, and the residual potential Vr after 30 seconds were measured. In addition, in order to determine the fatigue characteristics, charging at -7.5 KV and exposure at 30 lux was repeated for 1 hour using the above device, and the surface potential after fatigue was y/, 1 surface potential V'o.
, the exposure amount E' 1/2 and the residual surface potential V'r were measured. room temperature (25°C, 55% R) I), low temperature and low humidity (10°C, 15% R) I), and high temperature and high humidity (30°C, 9
0%RH) results are shown in Table-1, Table-2, and Table-3, respectively.

Table 2 (Low Temperature) Table 3 (High Temperature) Even in exposure using coherent light such as a printer, the generation of abnormal images due to optical interference can be prevented.

Patent Attorney Toshiaki Ikeura, Patent Attorney Rico Co., Ltd. (and 1 other person, Example 2 and Example 3)
A drum-shaped electrophotographic photoreceptor was attached to a laser beam printer (30°C, 90% RH),
(15° C., 20% RH), the electrophotographic photoreceptor was repeatedly fatigued by printing 5,000 sheets continuously, and the quality of one image was evaluated. 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 includes, on a substrate, zirconium oxide particles and tin oxide particles surface-treated with a fluorine surface treatment agent, and preferably an aliphatic incyanate compound, N
By providing an undercoat layer using a polyacetal resin as a binder resin, which is reaction-cured with a GO10H ratio of 115 to 5/1, it has high sensitivity and even after repeated charging exposures, the charge at the 4th position does not rise. It has the remarkable characteristics of being fast and having a small residual potential.

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

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 surface-treated with zirconium oxide particles and tin oxide particles with a fluorine-based surface treatment agent. An electrophotographic photoreceptor comprising: and a binder resin. (2) The electrophotographic photoreceptor according to claim 1, wherein the binder resin is a resin obtained by blending a polyvinyl acetal resin and an aliphatic isocyanate and curing the mixture by reaction.