JPH01269974A - Method for recovering fatigue of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To recover fatigue of an electrophotosensitive body, and to improve environmental dependency thereof by heat-treating a specified org. sensitive body which has become fatigued by repetitive use. CONSTITUTION:A photosensitive layer consisting primarily of a charge generating material and at least one kind among charge transfer materials expressed by the formula I-VI, is formed on an electroconductive base, and an org. electrophotosensitive body which has become fatigued by the repetition of charge and exposure is heat-treated. In the formula I, each R1-R4 is hydrogen atom, etc.; Ar1 is an aryl group; Ar2 is an arylene group; n is zero or 1. In the formula II, R1 is a lower alkyl group, alkoxy group, or a halogen atom; n is an integer 0-4. Thus, an electrophotosensitive body is recovered from fatigue. Its durability is improved, and its environmental dependency is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering from fatigue of an organic electrophotographic photoreceptor using a specific charge transport material.

In recent years, organic photoreceptors have begun to be used as photoreceptors for electrophotography, as they are more advantageous in terms of cost, productivity, and pollution than inorganic photoreceptors such as selenium photoreceptors. Organic photoreceptors basically have an organic photoconductive layer provided on a support, and the types include organic photoconductor-only types such as PVK (polyvinylcarbazole); PVK-TNF (2°4
．． 7-dolinitrofluorenone);
Organic photoconductors such as phthalocyanine pigments to resin-dispersed types; functionally separated types such as a charge generation layer and a charge transfer layer are known, and among them, functionally separated types are attracting attention. However, conventional organic photoreceptors suffer from significant pre-exposure fatigue, so...
It has low f-conductivity, poor charge retention in the dark (large dark decay), and is subject to repeated use. Deterioration of these characteristics,
That is, fatigue is large, and the residual potential gradually accumulates, resulting in uneven density, fog, and, in the case of reversal development, background smear on the image. Therefore, in order to eliminate these drawbacks, for example, in the case of a functionally separated type, an inorganic material layer such as Sin, A et al. (Unexamined Japanese Patent Publication No. 55-14
No. 2354) and metal powder (Japanese Unexamined Patent Publication No. 60-21436)
4) is known to be included.

In addition to functionally separated type photoreceptors, polyamide resins (JP-A-58-30757, JP-A-58-98739), alcohol-soluble polyamide resins (JP-A-60) are used as subbing layers for general organic photoreceptors. -196766),
Water-soluble polyvinyl butyral resin (JP-A-60-232
No. 553), polyvinyl butyral resin (Japanese Unexamined Patent Publication No. 553
It has been proposed to provide a resin layer such as Japanese Patent No. 8-106549).

However, the organic photoreceptors described above are still insufficient in improving the deterioration in chargeability and charge retention due to repeated use, and further improvements have been desired.

In the environment in which copying machines are used, regardless of the roughness of the photoconductor, under high temperature and high humidity conditions, image blurring, image temperature drop by 1 degree, etc. may occur, and at low temperatures, condensation on the photoconductor f1, etc. There are problems such as background stains [2].

Regarding the environmental dependence of this photoreceptor, JP-A No. 6
Japanese Patent No. 1-7843 discloses J'-, which can reduce the relative humidity of a photoreceptor under high temperature and high humidity conditions by heating the support under the photoreceptor layer to a relatively low temperature using a planar heating element. JP-A-62-121482 discloses a method of blowing hot or cold air onto a photoreceptor, which is said to prevent dew condensation on the photoreceptor at low temperatures and deterioration of the photoreceptor at high temperatures.

The purpose of the present invention is to heat-treat a specific organic photoreceptor that has become fatigued due to repeated use, and to recover the fatigue.
An object of the present invention is to provide a method for recovering from fatigue of an electrophotographic photoreceptor that can improve environmental dependence.

Furthermore, the method for recovering from fatigue of an electrophotographic photoreceptor according to the present invention comprises disposing a charge generating substance and at least one charge transporting substance represented by the following general formulas (I) to (VI) on a conductive support. It is characterized in that it is provided with a photosensitive layer as a main component, and heat-processes an organic electrophotographic photoreceptor that has become fatigued by repeating at least the steps of charging and exposure.

(However, Lr R3 and R4 represent a hydrogen atom, a substituted or unsubstituted lower alkyl group, a W-substituted or unsubstituted aryl group, Ar represents a substituted or unsubstituted aryl group, and Ar represents a substituted or unsubstituted aryl group. It represents an unsubstituted arylene group, and Ar and R1 may jointly form a ring.

n is an integer of O or 1. ) (However, R1 represents a lower alkyl group, a lower alkoxy group, or a halogen atom, n represents an integer of 0 to 4, and Lr
L may be the same or different and represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a halogen atom,
) (However, R,, R,, R, may be the same or different,
(represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a phenyl group, a fe, noxy group, or a halogen atom) (However, R4 represents a lower alkyl group, a 2-, hydroxyethyl group, or a 2-chloroethyl group, and R2 represents a lower represents an alkyl group, benzyl group, or phenyl group, and R1 represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a di-lower alkylamino group, or a nitro group) (However, Rx, R,, R,, R4 and RG is Mizu SM child,
represents a lower alkyl group, a lower alkoxy group, a substituted or unsubstituted di-lower alkylamino group, a dibenzylamino group, or a halogen atom; R8 represents a lower alkyl group or a benzyl group; (represents a substituted naphthalene ring, anthracene ring, or styryl group; or a pyridine ring, furan ring, or thiophene ring, and R represents a lower alkyl group or a benzyl group). However, repeated use, that is, repeating at least the charging and exposure steps, can cause deterioration of characteristics such as chargeability and charge retention, that is, fatigue. It was discovered that the damage could be recovered by heat treatment (performed in the dark), and the present invention was achieved.

The structure of the organic electrophotographic photoreceptor itself used in the method of the present invention is exactly the same as the conventional one. Examples of the structure include those shown in FIGS. 1 to 4.

That is, the photoreceptor shown in FIG.
4 in a single layer configuration. Figure 2 (a) and (
In the photoreceptor b), the photoreceptor layer 14 is composed of a charge generation layer 21 and a charge transport layer 22 stacked together. 3 and 4 are modified examples of FIGS. 1 and 2, in which an intermediate M13 is provided between the conductive support 11 and the photosensitive member M14, and FIG. Insulating protection M1 on the photosensitive layer 14
5.

The conductive support 11 may be one that exhibits conductivity with a volume resistance of 1016Ω1 or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, and platinum, and metal oxides such as tin oxide and indium oxide. covered with film or drum-shaped plastic or paper,
Or aluminum, aluminum alloy, nickel.

Examples include stainless steel plates, belts, drums, etc.

In the case of a single layer type, the photosensitive layer 14 is mainly composed of a charge generating material, a charge transporting material, and a binder resin. On the other hand, in the case of a laminated type, the photosensitive layer 14 consists of the charge generation layer 21 and the charge transport M22 as described above.
1 is composed mainly of a charge generating substance, and the charge transport layer 22 is composed mainly of a charge transporting substance and a binder resin.

Examples of the charge generating substance include CI Pigment Blue 25 [Color Index (:I) 21180],
CI Pigment Blue 41 (CI 21200)
benzidine derivative disazo pigments such as; xanthine dyes such as CI Acid Red 52 (CI 45100) and CI Basic Red 3 (CI 45210); phthalocyanine pigments having a porphyrin skeleton; azulenium salt pigments; Squaric salt pigments; having a carbazole skeleton Disazo pigments (described in JP-A-53-95033), disazo pigments having a styrylstilbene skeleton (described in JP-A-53-138229), disazo pigments having a distyrylbenzene skeleton (described in JP-A-53-138229),
3-133455), a trisazo pigment having a triphenylamine skeleton (Japanese Patent Application Laid-open No. 53-13254)
7), a disazo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728),
Disazo pigment with oxadiazole skeleton (Unexamined Japanese Patent Publication No. 5
4-12742), a disazo pigment having a fluorenone skeleton (described in JP-A-54-22834), a disazo pigment having a bisstilbene skeleton (described in JP-A-54-17733), Disazo pigments having a styryl oxadiazole skeleton
(described in Publication No. 2129).

Disazo pigments having a distyryl or rubazole skeleton (described in JP-A-54-17734), trisazo pigments having a carbazole skeleton (JP-A-57-195767)
CI Pigment Blue 16 (CI 7410);
Phthalocyanine pigments such as C.I. 0); C.I. Butt Brown 5 (CI 73410), C.I. Butt Dye (C
Indigo pigments such as I 73030); organic pigments such as perylene pigments such as Algol Scarlet B and Indus Thread Scarlet R (manufactured by Bayer AG).

Among these charge-generating substances, azo pigments are particularly preferred, and among azo pigments, disazo raw materials and trisazo pigments shown in the following formats (a□) to (V) are most preferred.

General formula (a8) ~ (,,,): (a) ring (b) ring (c) ring (however, Cp is a coupler residue, the same applies hereinafter) υ General formula (f) 20 General formula (g) D general Formula (h□) ~ (h4): CP-N=N-◎ko◎-N=N -cp General formula (i): N=N-CP General formula (j) ~ (j4) General formula (k): C, -N=N-@-■-@-N=N-CP general formula (previous)
~ (chi): ^ General formula (m,) ~ (mi.): (a) ring (b) ring d In addition, as the coupler residue CP in the above general formulas (81) to (v), for example, phenols , compounds with a phenolic hydroxyl group such as naphthols, aromatic amino compounds with an amino group or aminonaphthols with an amino group and a phenolic hydroxyl group, compounds with an aliphatic or aromatic enolic ketone group (active methylene group) Compounds having the following formulas (1) to (11) are preferably used.

[In the above formulas (1), (2), (3) and (4),
.

Y, , Z, m and n each represent the following.

(R1 and R2 represent hydrogen or a substituted or unsubstituted alkyl group, R2 represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group) Y = hydrogen, halogen, substituted or unsubstituted Alkyl group, substituted or unsubstituted alkoxy group, carboxy group, sulfone group, substituted or unsubstituted sulfa K.

(R4 represents hydrogen, an alkyl group or a substituent thereof, a phenyl group or a substituent thereof, and Y2 is a hydrocarbon ring group, an N-shaped ring thereof, a heterocyclic group or a substituent thereof.

a hydrocarbon ring group or a substituent thereof, a heterocyclic group or a substituent thereof, a styryl group or a substituent thereof, R represents hydrogen, an alkyl group, a phenyl group or a substituent thereof, or h and R1 are bonded thereto; Z: a hydrocarbon ring or a substituent thereof, or a heterocycle or a substituent thereof n: an integer of 1 or 2 m: an integer of 1 or 2] [Formula In (5) and (6), R1 represents a substituted or unsubstituted hydrocarbon group, and X is as defined above. ] Ar.

[In the formula, R represents an alkyl group, a carbamoyl group, a carboxyl group, or an ester thereof, Ar1 represents a hydrocarbon ring group or a substitute thereof, and X is the same as above. ] [In the above formulas (8) and (9), R represents hydrogen or a substituted or unsubstituted hydrocarbon group.

Ar represents a hydrocarbon ring group or a substituted product thereof. ] Examples of the hydrocarbon ring of Z in the above-format (1), (2), (3) or (4) include a benzene ring, a naphthalene ring, etc., and a heterocycle (which may have a substituent) ) can be exemplified by an indole ring, a carbazole ring, a benzolane ring, a dibenzofuran ring, etc. Examples of the substituent in ring 2 include halogen atoms such as chlorine atom and bromine atom.

As the hydrocarbon ring group in Y2 or R1.

Examples include phenyl group, naphthyl group, anthryl group, pyrenyl group, and heterocyclic groups include pyridyl group, thienyl group, furyl group, and indolyl group.

Examples include a benzofuranyl group, a carbazolyl group, a dibenzofuranyl group, and further examples of the ring formed by bonding R6 and R6 include a fluorene ring.

Is Y2 or R5 a hydrocarbon ring group or double? Examples of substituents on the FfR group or the ring formed by R5 and R2 include alkyl groups such as methyl, ethyl, propyl, and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy; and chlorine. atom, halogen atom such as bromine atom, dialkylamino group such as dimethylamino group or diethylamino group, halomethyl group such as trifluoromethyl group, nitro group, cyano group, carboxyl group or its ester, hydroxyl group, -So, Na
Examples include the sulfonic acid group of Nato.

Examples of substituents for the phenyl group of R4 include halogen atoms such as chlorine atoms and bromine atoms.

Representative examples of the hydrocarbon group in R7 or R9 are:
Examples include alkyl groups such as methyl, ethyl, propyl and butyl groups, aryl groups such as phenyl, and substituted products thereof.

As a substituent in the hydrocarbon group of R7 or R9,
Examples include alkyl groups such as methyl, ethyl, propyl, and butyl groups; alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy; halogen atoms such as chlorine and bromine; hydroxyl and nitro groups. .

Typical examples of the hydrocarbon ring group in Ar□ or Ar are phenyl group, naphthyl group, etc.
Substituents for these groups include alkyl groups such as methyl, ethyl, propyl, and butyl, alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy, nitro, chlorine, bromine, etc. Examples include halogen atoms, dialkylamino groups such as cyano groups, dimethylamino groups, and diethylamino groups.

Furthermore, among X, a hydroxyl group is particularly suitable.

Among the above coupler residues, the above -format (
2), (5), (6), (7), (8) and (9), and among these, those in which X in the general formula is a hydroxyl group are preferred;
) (Yl and 2 are the same as above) A coupler residue represented by the following is preferable, and a coupler residue represented by the general formula (z, y, and R2 are the same as above) is more preferable.

Furthermore, among the above-mentioned preferred coupler residues, general formula (12) or (13) 1\Zノ°ゝZ/' (z, Rx, R, and R6 are the same as above, and R1゜The above-mentioned substituents for Y2 can be exemplified.) Those represented by the following are suitable.

Specific examples of the coupler residue Cp are shown below.

(Continued) Therefore, specific examples of disazo or trisazo pigments represented by general formulas (al) to (v) include specific examples of the coupler residue Cp in these general formulas, but in the examples below, they are simplified. Therefore, No of the general formula and CpNo,
For example, an azo pigment represented by the formula is represented as rk-IJ.

In any case, the charge generating substances may be used alone or in combination of two or more.

Next, as the charge transport substance, the general formulas (1) to (VI) are used.
The one shown is used. Specific examples thereof are as follows.

(The following is a blank space) To Ar-CH=N-N ◇''・(■) These charge transport materials may be used alone or in combination of two or more.

As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-
Maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate resin.

Phenoxy resin, polycarbonate-1, cellulose acetate, ethyl cellulose, polyvinyl butyral, polysulfomal, polyvinyl toluene, poly-N-vinyl carbazole, polyurethane, acrylic resin, silicone resin, epoxy resin, melamine resin, phenolic resin, alkyd resin In the case of a single layer type, polyamide, polyketone, polyvinyl ketone, polyacrylamide, etc. can be used in combination.

Generally, in the case of a single-layer type photosensitive layer, a charge generating substance, a charge transporting substance, and a binder resin are dissolved or dispersed in a solvent such as tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, cyclohexanone, or methylene chloride. In the case of a laminated type, a charge-generating substance and, if necessary, a binder resin as described below may be dissolved or The dispersed liquid is coated on a support using a similar coating method and dried to form a charge generation layer, and then a liquid in which a charge transport substance and a binder resin are dissolved or dispersed is coated thereon using a similar coating method. , and drying to form a charge transport layer. Here, the binder resin for the charge generation layer includes polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, etc. can be mentioned. Note that a plasticizer, a leveling agent, etc. may be added to the single-layer type photosensitive layer or the charge transport layer, if necessary.

In any case, the thickness of the photosensitive layer is 5 to 1O in the case of a single layer type.
Appropriately, the thickness is about 0 .mu.m, and in the case of a laminated type, the appropriate thickness is about 0.01 to 5 .mu.m for the charge generation layer, and about 5 to 50 .mu.m for the charge transport layer.

The intermediate layer 13 provided between the support 11 and the photosensitive material 14 further improves the effects of the present invention.

It is provided for the purpose of improving adhesiveness, and its material is S.
in, A Q zO3, inorganic materials such as silane coupling agents, titanium coupling agents, chromium coupling agents, polyamide resins, alcohol-soluble polyamide resins,
Water-soluble polyvinyl butyral, polyvinyl butyral,
A binder resin with good adhesive properties such as PVA is used. In addition, ZnO, TiO are added to the resin with good adhesive properties.
2. A material in which ZnS or the like is dispersed can also be used. As a method for forming the intermediate layer, when an inorganic material is used, methods such as sputtering or vapor deposition are used, and when an organic material is used, a normal coating method is used. Note that the thickness of the intermediate layer is suitably 5 μm or less.

The protective layer 15 is provided for the purpose of protecting the surface of the photoreceptor, and materials used for this include ABS resin, AC8 resin, and olefin rubinyl monomer copolymer.

Chlorinated polyether, allyl resin, phenolic resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic Resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane.

Examples include resins such as polyvinyl chloride, polyvinylidene chloride, and epoxy resins. In addition, the protective layer contains fluororesin such as polytetrafluoroethylene, silicone resin, and titanium oxide, titanium oxide, etc. in order to improve wear resistance.
Dispersed inorganic materials such as tin oxide and potassium titanate can be added. A normal coating method is adopted as a method for forming the protective layer. Naoyasu! ! The layer thickness is 0.5
A suitable thickness is about 10 μm.

As mentioned above, the organic photoreceptor described above becomes fatigued by repeated use. The method of the present invention is to recover the fatigued organic photoreceptor by heat treatment (in the dark).

The second heat treatment method is not particularly limited;
For example, the front surface (photosensitive side) or back surface (support side) of the photoreceptor may be exposed to an infrared lamp (heat ray) or hot air.

High frequency, PTC heating element (heating element with PTC characteristics), heat roller (infrared lamp, PTC heating element, resistance heater, heat pipe passing heat medium, etc. as a heat source are built-in, or the surface is exposed) or the support of the photoreceptor is made of a planar heating element. In this case, the support is made of a plastic film charged with a conductive substance such as carbon powder or metal powder. Or,
Alternatively, there may be a method in which such conductive plastics are laminated by coating, adhesion, etc.), a method in which a direct current is passed through the conductive plastic, and the material is heated. These methods may be selected as appropriate depending on the shape of the photoreceptor (usually belt-shaped or drum-shaped); however, in the case of a drum-shaped photoreceptor, a heat source such as that used in the above-mentioned thermal roller may be incorporated. In either method, cooling means such as cold air or cooling pipes may be used in combination to adjust the temperature.

When this heat treatment method is actually applied to the specific organic photoreceptor of the present invention, heating is performed while the photoreceptor is in use.

It may be carried out continuously, intermittently or occasionally [at the beginning of use, during use (for example, when a fatigue detection device is attached and fatigue occurs), or only just before use].
When heating continuously or intermittently (when the heating interval is short), if it is too low, it will not be effective, and if it is too high, it will stress or destroy the photosensitive layer. The heating temperature is usually 35-100'C, preferably! , t50=approximately 80°C. - When heating occasionally or intermittently (when the heating interval is long), the temperature may be higher than 80°C (maximum 150"C, preferably about 120"C), depending on the usage time. The higher the temperature and the longer the heating time, the more effective the recovery from fatigue of the photoreceptor.

In addition, the sensitivity of the photoconductor tends to deteriorate as the temperature decreases, so from this point of view as well, it is preferable to heat the photoconductor at a temperature as high as possible within the above range. (for example, at 100° C. or higher), it is preferable to stop the copying machine or printer, or move the fixing, developing, and exposing sections away from the photoreceptor.

The present invention will be explained below by way of examples. All of the sections are heavy-duty sections.

Examples 1 to 132 An AQ drum (with built-in heat pipe) having a diameter of 80 m and a length of 340 W was coated with an intermediate layer forming liquid, a charge generation layer forming liquid, and a charge transport layer forming liquid having the following compositions in order by dip coating, and then dried to form a zero
．． An organic electrophotographic photoreceptor was prepared by forming an intermediate layer with a thickness of 37 zm, a charge generation layer with a thickness of 0.1 μm, and a charge transport layer with a thickness of 20 μm. The charge generation layer forming liquid was dispersed in a ball mill for 48 hours.

Intermediate layer forming liquid: water i
so part methanol 1
50 parts Charge generation layer forming liquid: 2 parts of azo pigment listed in Table 1 80 parts of hexanone 18 parts of methyl ethyl getone Charge transport layer forming liquid: 9 parts of charge transport substance listed in Table 1 81 parts of methylene chloride Next, each photoreceptor was set in an electrophotographic copying machine (Coby FT4080 manufactured by Ricoh, modified to be negatively charged), and while heating the drum to 50±2°C by passing hot water through a heat pipe, 8,000 sheets were continuously printed. Copies were made, and the initial (3rd to 5th) and 8000th surface potentials were determined. In this case, the probe of the surface electrometer was set so that the surface potential of the photoreceptor immediately after charging could be measured.The environmental conditions at this time were 20 DEG C. and 60% RH.

For comparison, continuous copying was carried out in the same manner except that the photoreceptors of each example were not heated, and the same tests were conducted.

The above results are shown in Table 1, and the storms of the comparative examples correspond to the positives of the examples.

Examples 133 to 264 An intermediate layer forming liquid, a charge generation layer forming liquid, and a charge transport layer forming liquid having the following compositions were sequentially applied by dip coating on an AQ drum (with built-in resistance heater) having a diameter of 120 nn and a length of 340 IIn, and dried. An organic electrophotographic photoreceptor was prepared by forming an intermediate layer with a thickness of 3.5 μm, a charge generation layer with a thickness of 0.2 μm, and a charge transport layer with a thickness of 22 μm. The intermediate layer forming liquid and the charge generation layer forming liquid were dispersed in a ball mill for 12 hours and 36 hours, respectively.

Intermediate layer forming liquid: Titanium dioxide 10 parts Polyvinyl butyral (Eslec BL-1 manufactured by Tanemizu Chemical Industry Co., Ltd.)
1 part toluylene-2,4-diisocyanate
0.2 parts 2-butanone
100 parts 4-methyl-2-pentanone
60 parts Charge generation layer forming liquid: Azo pigment shown in Table 2 3 parts Cyclohexanone 160 parts Cyclohexane 40 parts Charge transport store forming liquid: Charge transport material shown in Table 2 9 parts Polyarylate (Unitika Co., Ltd. 17Ll- 100)
11 parts methylene chloride
70 parts chlorobenzene 1
Copy 0 Next, each photoreceptor was set in an electrophotographic copying machine (Ricoh Copy FT7050 modified to be negatively charged), copying was stopped every 5,000 copies, and the drum was heated to 100°C with a resistance heater. After that, 10,010 copies were made intermittently by cooling the paper to room temperature using a separately provided fan and starting copying again. The environmental conditions at this time are 25
°C-45%R)l. For comparison, intermittent copying was performed using the same method except that the photoreceptors of each example were not subjected to the heat treatment (including the cooling step) and copying was stopped during that time.

The initial (10th) and 10010th image densities (rD) of the resulting copies were measured using a Macbeth densitometer.

The above results are shown in Table 2, and the numbers in the comparative examples correspond to the NQs in the examples.

(Leaving space below) Examples 265 to 396 1 A charge generation layer forming liquid and a charge transport layer forming liquid having the following compositions were sequentially applied by dip coating onto a long polyester film support having a conductive layer, and dried to a thickness of 0.2 μm. After forming a charge generation layer with a thickness of 18 μm and a charge transport layer with a thickness of 18 μm, both ends were joined to prepare an organic electrophotographic photoreceptor belt.

The charge generation layer forming liquid was dispersed in a ball mill for 72 hours.

Charge generation layer forming liquid: Azo pigment listed in Table 3 10 parts Cyclohexanone 500 parts Methyl isobutyl ketone 200 parts Charge transport layer forming liquid: Charge transport substance listed in Table 3 10 parts Tetrahydrofuran 180 parts Next, each photosensitive material The body is an electrophotographic copying machine (Copy FT2050 manufactured by Ricoh Co., Ltd., in which the driving roller that supports the photoreceptor belt from the support side and the driven roller of the plurality of driven rollers are modified into a thermal roller that uses a planar heating element as a heat source) While heating the belt to 40±3℃ with a heat roller, 7500 sheets were continuously copied, and the initial (1st sheet)
And the surface potential after copying 7,500 sheets was measured. The environmental conditions at this time were 18° C. and 35% RH.

For comparison, continuous copying was carried out in the same manner except that the photoreceptors of each example were not heated, and the same tests were conducted.

The above results are shown in Table 3, where Na in the comparative examples corresponds to Na in the examples.

(Left space below) Examples 397 to 528 A charge transport layer forming liquid, a charge generating layer forming liquid, an intermediate layer forming liquid and a protective layer forming liquid having the following compositions were sequentially dip-coated onto a drum having a diameter of 80 m and a length of 340 mm. , 15μm each after drying
An organic electrophotographic photoreceptor was prepared by forming a charge transport layer with a thickness of 3 μm, a charge generation layer with a thickness of 3 μm, an intermediate layer with a thickness of 0.5 μm, and a protective layer with a thickness of 5 μm. The charge generation layer forming liquid and the protective layer forming liquid were heated in a ball mill for 40 hours and 80 hours, respectively.
It is time-dispersed.

Charge transport layer forming liquid: Charge transport substance listed in Table 4 10 parts Tetrahydrofuran 100 parts cyclohexanone 80 parts Charge generation layer forming liquid: Azo pigment listed in Table 4 2 parts cyclohexanone 97 parts Intermediate layer forming liquid : Boryamide (CM-4000 manufactured by Toshisha)
4 parts methanol 1
00 parts Protective layer forming liquid: Styrene - methyl methacrylate - 2-hydroxyethyl methacrylate copolymer 8 parts Conductive titanium
10 parts toluene
240 parts butanol
60 copies Next, each photoreceptor was set in an electrophotographic copying machine (Coby FT5510 manufactured by Ricoh Co., Ltd.), copying was stopped every 3000 copies, and the photoreceptor was exposed to the surface using an infrared lamp installed on the photosensitive layer side of the photoreceptor drum. 4 in temperature
After heating to 0° C., cooling to 20° C. and restarting copying, 12,000 copies were made intermittently, and the surface potentials of the initial (10th) and 12,000th copies were measured. In this case, a probe of a surface electrometer was set so that the surface potential of the photoreceptor could be measured immediately after charging. The environmental conditions at this time were 30° C. and 80% RH.

For comparison, the photoreceptors of each example were subjected to intermittent copying in the same manner except that no heat treatment (including the cooling step) was performed and copying was stopped during that time, and tests were conducted in the same manner.

The above results are shown in Table 4, where Nα of the comparative example corresponds to Nα of the example.

(The following is a blank space) Examples 529 to 660 An intermediate layer forming liquid, a charge generation layer forming liquid, and a charge transporting layer forming liquid having the following compositions were sequentially dip-coated on a long polyester film support having a layer A, and 0.2 each after drying
μm thick intermediate layer, 0.1μm thick charge generation layer and 20μm thick
An IJ organic electrophotographic photoreceptor belt was prepared by forming a charge transport layer having a thickness of m and then joining both ends thereof. The charge generation layer forming liquid was dispersed in a ball mill for 60 hours.

Intermediate layer forming liquid: Polyvinyl alcohol (Denka Poval I+-20 manufactured by Denki Kagaku Kogyo Co., Ltd.)
2 parts water
2°0 parts methanol
100 parts Charge generation layer forming liquid: Azo pigment listed in Table 5 3 parts Cyclohexanone 97 parts Charge transporting layer forming liquid; Charge transport substance listed in Table 5 10 parts Polycarbonate (Teijin Panlite -1300) )
10 parts terahydrofuran
90 parts dioxane 9
Part 0 Next, each photoreceptor was transferred to an electrophotographic copying machine (a driven roller of the yjA moving roller and a plurality of driven rollers that support the photoreceptor belt from the support side).

It was set in a copying machine (FT2070 manufactured by Ricoh Co., Ltd.) which had been modified to a thermal roller with a built-in PTC heating element, and while the belt was heated to 35±3°C by the thermal roller, 7,000 sheets were continuously copied, and the initial (5th sheet) And the image condition after copying the 7000th sheet was evaluated. The environmental conditions at this time are 1
0°C-60%RH.

For comparison, continuous copying was performed using the same method except that the photoreceptors of each Example were not heat-treated during copying, and the image condition was evaluated in the same manner.

The above results are shown in Table 5, where Nα of the comparative example corresponds to Nα of the example. Further, in the table, O indicates good, ○ to Δ is rather good, X to Δ is almost poor, and × indicates that image formation is not possible.

Examples 661 to 792 Intermediate layer forming liquid 5 of the following composition was sequentially applied by dip coating to an All drum having a diameter of 120 m and a length of 340 m, a charge generation layer forming liquid and a charge transport layer forming liquid, and dried to form an intermediate layer having a thickness of 5 μm, respectively.
An organic electrophotographic photoreceptor was prepared by forming a charge generation layer with a thickness of 0.3 μm and a charge transport layer with a thickness of 25 μm. The intermediate layer forming liquid was dispersed in a ball mill for 12 hours.

Intermediate layer forming liquid: Titanium dioxide 10 parts Polyvinyl butyral (S-LEC BL-1 manufactured by Block Chemical Industry Co., Ltd.) 1
Part toluylene-2,4-diisocyanate 0
．． 2 parts 2-butanone 1
00 parts 4-methyl-2-pentanone
60 parts Charge generation layer forming liquid: Azo pigment shown in Table 6 2 parts Polyester (Vylon 200 manufactured by Toyobo Co., Ltd.) 1 part Cyclohexanone 97 parts Charge transport layer forming liquid: Charge transport substance shown in Table 6 9 parts Polyester Acrylate (Unitika 1lU-100) 1
1 part methylene chloride 70
1 part chlorobenzene 10 parts Next, each photoreceptor was set in an electrophotographic copying machine (Coby FT6080 manufactured by Ricoh, modified to be negatively charged).
After making 9,990 continuous copies, the photoreceptor was taken out of the copying machine and heated using a light-shielding external heating device (equipped with a drum-shaped sheet heating element that can heat the photoreceptor drum from the photosensitive layer side in a light-shielded state). Heat treatment at 130°C for 20 minutes,
Then, cool it to room temperature, put it back into the copier, and make another 10 sheets (
10,000 copies in total), initial (10th copy)
And the surface potential of the 10,000th sheet was measured. in this case.

A surface electrometer probe was set so that the surface potential of the photoreceptor immediately before development could be measured. The environmental conditions at this time were 25° C. and 50% RH.

For comparison, the photoreceptors of each example were subjected to intermittent copying in the same manner except that they were not subjected to heat treatment (including the cooling step) and tested in the same manner.

The above results are shown in Table 6, and each of the comparative examples corresponds to the islands of the examples.

Examples 793 to 924 An intermediate layer forming liquid, a charge generation layer forming liquid, and a charge transport layer forming liquid having the following compositions were sequentially applied by dip coating onto an AΩ drum having a diameter of 80 IIn and a length of 340 m, and dried to form an intermediate layer having a thickness of 0° and 3 μm. An organic electrophotographic photoreceptor was prepared by forming a 0.2 μm thick charge generation layer, and a 20 μm thick charge transport layer.

Intermediate layer forming liquid: Water 1
50 parts methanol 20
0 parts Charge generation layer forming liquid: Azo pigment listed in Table 6 2 parts Tetrahydrofuran 80 parts Ethyl cellosolve 120 parts Charge transporting layer forming liquid: Charge transport material listed in Table 6 io part Base methylene chloride 80 parts Next, each The photoreceptor was set in an electrophotographic copying machine (Coby FT5050 manufactured by Ricoh, modified to be negatively charged), and a separately installed high-frequency induction heating device (a 2.45 GHz magnetron was used as the high-frequency power source, and a ferrite-based ferromagnetic material was heated). While the photoreceptor was heated to 50±2° C. using a laminate of dispersed resin plates and one pole as a heating element, 9000 sheets were subjected to continuous picobeaming. The environmental temperature at this time was 23℃-50%RH.
It is.

For comparison, continuous copying was performed using the same method except that high-frequency heating was not performed.

The image densities of the obtained copies at the initial stage (5th copy) and at the 9000th copy were measured using a Macbeth densitometer.

The above results are shown in Table 7, where Nα of the comparative examples correspond to those of the examples.

(The following is a blank space) According to the method of the present invention, fatigue can be recovered by heat-treating a specific organic photoreceptor whose properties such as chargeability and charge retention have deteriorated due to repeated use, that is, which has become fatigued. It is possible to constantly form high-quality images by improving durability and improving environmental dependence.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views of examples of organic electrophotographic photoreceptors used in the method of the present invention. 11... Conductive support 13... Intermediate layer 14...
・Photosensitive Jil 15...Protective layer 21...
Charge generation layer 22...Charge transport layer Patent applicant Ricoh Co., Ltd. - Figure 1 Figure 3 Figure 2 (,) Figure 4 Figure 2. .

Claims (1)

[Claims] 1. A charge generating substance and the following general formula (I
) to (VI), the organic electrophotographic photoreceptor is heated by repeating at least the steps of charging and exposure. A method for recovering from fatigue of an electrophotographic photoreceptor, the method comprising: treating the electrophotographic photoreceptor; ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (However, R_1, R_2, R_3 and R_4 are hydrogen atoms,
represents a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, Ar_1 represents a substituted or unsubstituted aryl group, Ar_2 represents a substituted or unsubstituted arylene group, and Ar_1 and R_2 jointly represent n may form a ring; n is an integer of 0 or 1; ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) (However, R_1 represents a lower alkyl group, lower alkoxy group, or halogen atom, n represents an integer from 0 to 4, and R_2 and R_3 may be the same. They may be different and represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a halogen atom.) ▲There are numerical formulas, chemical formulas, tables, etc.▼...(III) (However, R_1, R_2, and R_3 may be the same or different. may represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a phenyl group, a phenoxy group, or a halogen atom.) ▲Mathematical formulas, chemical formulas, tables, etc.▼...(IV) (However, R_1 is lower alkyl R_2 represents a lower alkyl group, benzyl group or phenyl group, R_3 represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a di-lower alkylamino group. or represents a nitro group.) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(V) (However, R_1, R_2, R_3, R_4 and R_6 are hydrogen atoms, lower alkyl groups, lower alkoxy groups, substituted or unsubstituted. represents a di-lower alkylamino group, dibenzylamino group, or halogen atom, and R_5 represents a lower alkyl group or benzyl group.) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(VI) (However, each Ar is (R represents a substituted or unsubstituted naphthalene ring, anthracene ring, or styryl group; or a pyridine ring, furan ring, or thiophene ring, and R represents a lower alkyl group or a benzyl group.)