JPS63243945A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide high sensitivity and to prevent deterioration in electrostatic chargeability due to fatigue by pre-exposure and reduction in electric potential by electrostatic charge due to repeated use by forming an electric charge generating layer on an electrically conductive support with an electric charge generating substance and mono- or diester polyethylene glycol. CONSTITUTION:An electric charge generating layer 1 is formed on an electrically conductive support 3 with an electric charge generating substance and mono- or diester of polyethylene glycol (PEG). An electric charge transferring layer 2 is then formed on the layer 1 to obtain an electrophotographic sensitive body. Since the mono- or diester of PEG is chemically adsorbed on an electric charge transferring substance and acts as the recombination center of electric charges generated by light absorption, electric charges generated by fatigue by pre-exposure recombine rapidly and vanish, so reduction in the electric potential of the sensitive body by electrostatic charge is suppressed. This effect is produced even during repeated use. The title sensitive body which has high sensitivity, hardly undergoes deterioration in the electrostatic chargeability due to fatigue by pre-exposure and undergoes no reduction in electric potential by electrostatic charge even after repeated electrostatic charge and exposure is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in an electrophotographic photoreceptor having a layer in which a charge generating substance is dispersed.

[Prior art]

2. Description of the Related Art Electrophotographic photoreceptors have been known that are provided with a charge generation layer containing a charge generation substance and various resins.

Examples of this include polyvinyl butyral (Japanese Patent Application Laid-open No. 58-105154), fatty acid cellulose ester (
JP-A-58-166353), acrylic resin with Tg of 70°C or less and acid number 10-40 (JP-A-58-192)
No. 040), a resin with a Tg of 70°C or less, and a resin with a Tg of 75
A mixture of resins with a temperature of ℃ or above
No. 9), which is redispersed by adding a less compatible resin-solvent system to the charge-generating substance-resin-solvent system (Japanese Patent Laid-Open No. 56
-12646), polyvinylpyrrolidone (Unexamined Japanese Patent Publication No. 12646), polyvinylpyrrolidone
-113140), polyvinyl formal resin (Japanese Patent Application Laid-Open No. 61-235844).

However, conventionally known photoreceptors have a problem in that sensitivity and chargeability against pre-exposure fatigue vary depending on the mixing ratio of the charge generating substance and the binder resin.

In other words, in conventional photoreceptors, sensitivity can be increased by reducing the amount of binder resin used for the charge-generating substance, but the chargeability deteriorates significantly due to pre-exposure fatigue, and conversely, the use of binder resin for the charge-generating substance If the amount is increased, it is possible to suppress a decrease in chargeability due to pre-exposure fatigue, but this includes the problem of a significant decrease in sensitivity.

Furthermore, the conventional photoreceptor also has the disadvantage that the potential of the band fjL decreases significantly during repeated charging and exposure.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that has high sensitivity, exhibits significantly less deterioration in chargeability due to pre-exposure fatigue, and does not cause a decrease in charging potential even after repeated charging and exposure.

〔composition〕

According to the present invention, in an electrophotographic photoreceptor having at least a layer in which a charge generating substance is dispersed on a conductive support,
There is provided an electrophotographic photoreceptor characterized in that a layer in which a charge generating substance is dispersed is composed of a charge generating substance and a mono- or diester of polyethylene glycol.

The electrophotographic photoreceptor of the present invention has a layer in which a charge-generating substance is dispersed and is composed of a charge-generating substance and mono- or diester of polyethylene glycol, so that it has high sensitivity and significantly reduces chargeability deterioration due to pre-exposure fatigue. Moreover, it has a remarkable effect that the charging potential does not decrease even after repeated charging and exposure. Generally, high-sensitivity photoreceptors have reduced chargeability due to pre-exposure fatigue. The longer the charge generated by light absorption remains on the photoreceptor in a movable state, and the greater the number of charges, the more significant the reduction in chargeability due to pre-exposure fatigue becomes. That is, even if the JiF TIE operation is performed in a state where charges generated by light absorption remain, the surface charges are neutralized by the movement of the remaining carriers, so the surface potential does not increase until the residual potential is consumed. Therefore, the increase in surface potential is delayed by the amount of pre-exposure fatigue, and the apparent charged potential is lowered.

As a result of intensive study to improve this point, the present inventors found that
It has been discovered that the above-mentioned drawbacks can be overcome by incorporating a mono- or diester of polyethylene glycol into the layer in which the charge-generating substance is dispersed, and the present invention has been completed.

The reason why the present invention has such remarkable effects is not necessarily clear at this point, but the reason is that mono- or diester of polyethylene glycol is chemically adsorbed to the charge-generating substance,
Because it becomes a recombination center for charges generated by light absorption,
This is thought to be due to the fact that charges generated due to pre-exposure fatigue are quickly recombined and disappear, thereby suppressing a decrease in the charged potential of the photoreceptor.

Furthermore, the effect on pre-exposure fatigue as described above is similarly manifested during actual use where charging and exposure are repeated. Even after repeated exposure and exposure, the drop in charging potential is extremely small.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 to 3 are drawings illustrating typical layer structures of the electrophotographic photoreceptor of the present invention.

FIG. 1 shows a structure in which a charge generation layer 1 and a charge transfer layer 2 are sequentially laminated on a conductive support 3, and FIG.
The stacking order of the charge generation layer 1 and the charge transfer layer 2 in the figure is reversed, and the charge generation layer 1 is formed by a coating method such as a spray coating method that does not disturb the charge transfer layer 2. Ru.

In FIG. 3, a subbing layer 4 is provided between the conductive support 3 and the charge generation layer I in FIG. 1.

When the purpose of the undercoat layer is to prevent light interference in the photoreceptor for laser printers, a light-scattering undercoat layer or a light-absorbing undercoat layer is used, and when the purpose is adhesiveness and flexibility, an adhesive is used. Polyamide, polyester, vinyl chloride with good properties
A resin undercoat layer such as vinyl acetate copolymer or polyvinyl butyral is used.

Next, each constituent material used in the present invention will be explained.

The conductive support is intended to supply charges of opposite polarity to the charged charges to the substrate side, and has an electrical resistance of 1.
0" ΩcI11 or less and can withstand the film formation conditions of the charge generation layer, charge transfer layer, and even undercoat layer. Examples of these include A Q , Ni,
The surfaces of electrically conductive metals and alloys such as Cr, Zn, and stainless steel, inorganic insulating materials such as glass and ceramics, and organic insulating materials such as polyester, polyimide, phenolic resin, nylon resin, and paper are coated by vacuum evaporation, sputtering, AQ, N by methods such as spray painting
i, Cr, Zn, stainless steel, carbon, SnO,,I
Examples include those coated with an electrically conductive substance such as n, 0, etc. and subjected to conductive treatment.

The layers in which the charge generating substance is dispersed are shown in FIGS. 1, 2 and 3.
As shown in the figure, it is constituted as a charge generation layer in a laminated photosensitive layer, and is formed from a charge generation substance and mono- or diester of polyethylene glycol.

As the mono- or diester of polyethylene glycol, those represented by the following general formulas (1) and (II) are used.

R, -C-0-→CH2CH,O←-H(1)II
n (wherein R and R3 are hydrocarbon groups having 1 to 30 carbon atoms,
Preferably 10 to 20 hydrocarbon groups, n indicates the average number of added moles, and represents a real number of 1 or more, preferably 1 to 30. ) This mono- or diester of polyethylene glycol is
These are conventionally known, and various commercially available ones are used in the present invention, but those with a molecular weight of 100 to 1000
0, preferably 100 to 2,000.

Specific examples of the compound of general formula (1) include Sanyo Chemical Co., Ltd.'s Ionet series; MS-400, MS-1
000°MO-200, MO-400, MO-600;
Santobar TE-106, Daiichi Kogyo Seiyaku Co., Ltd.'s Neugen ES series; NOF Corporation's Nonion-L series, Nonion-S series, Nonion-〇 series,
Examples include Nonion-T series.

Further, as specific examples of the compound of general formula (II), Sanyo Chemical Co., Ltd.'s Ionet O series; DL-200;
O3-300, O3-400, Do-200%Do-4
00, Do-600, Do-1000, Santopearl G
E-70; Nonion O5-6011 from Nippon Oil & Fats Co., Ltd.
Examples include N.

The amount of polyethylene glycol mono- or diester used is 0.001 part by weight of the charge generating substance described below.
-2 parts by weight, preferably 0.1-1 parts by weight.

If the amount used is outside the above range, the intended purpose of the present invention will not be fully achieved.

As the charge generating substance, for example, CI Pigment Blue 25 [Color Index (CI) 21180]
, CI Pigment Red 41 (CI 21200)
, Sea Eye Acid Red 52 (CI 45100),
CI Basic Red 3 (CI 45210), further contains a phthalocyanine pigment having a porphyrin skeleton, an azulenium salt pigment, a squalic salt pigment, an azo pigment having a carbazole skeleton (described in JP-A-53-95033), and a stilstilbene skeleton. (described in JP-A No. 53-138229), azo pigments having a triphenylamine skeleton (described in JP-A-53-132
547), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728),
Azo pigments having an oxadiazole skeleton
12742), an azo pigment having a fluorenone skeleton (described in JP-A No. 54-22834), an azo pigment having a bisstilbene skeleton (described in JP-A-54-17)
733)), azo pigments having a distyryloxadiazole skeleton (described in Japanese Patent Application Publication No. 15/1982-2129), azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-17734), described), triazo pigments having a carbazole skeleton (Japanese Patent Application Laid-Open No. 57-195
No. 767, No. 57-195768), and CI Pigment Blue 16 (CI 74).
100), C.I. Butt Brown 5 (CI 73410), C.I. Butt Dye (
Organic pigments such as indigo pigments such as CI 73030) 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.

Specific examples of azo pigments are shown below.

face jl positive - one red tooth one tooth - f- 1 and h - one koshi one one face" 1 phrase - 1181111
--com [7to-No u
□1 crosspiece −−1Δ−11 face”1−
-11Δ---mll')J! Q
-11 to 111 red mutual h
- One piece, one face" L Tsumugi - - One piece, one face" Seven [Yes]
-1-A---Face" L teeth
-ri face” [corner -11 to 11-LLI
! iQ -118111 face 4F teeth
--8=^[odd teeth
□A face'' [Tooth -11---Face 1 inch~ -8□ 11uuQ -1----The appropriate thickness of the charge generation layer 1 is about 0.05 to 2 μm,
Preferably it is 0.1 to 1 μm.

'The burden generating layer 1 can be formed by dissolving or dispersing polyethylene glycol mono- or diester and a charge-generating substance in a suitable solvent, applying the solution, and drying the solution. As a solvent, benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexanone, methyl cellosolve, ethyl cellosolve, etc. can be used alone or in combination. can.

The charge transfer layer 2 can be formed by dissolving or dispersing a charge transfer substance and a resin binder in a suitable solvent, coating the solution on the charge generation layer 1, and drying it. Moreover, a plasticizer, a leveling agent, etc. can also be added if necessary.

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

As the resin binder, 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, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyltoluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine Examples include thermoplastic or thermosetting resins such as resins, urethane resins, phenol resins, and alkyd resins.

As the solvent at this time, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. can be used.

The thickness of the charge transfer layer 2 is suitably about 5 to 100 μm.

Furthermore, in the present invention, as described above, an undercoat layer can be provided between the conductive support and the photosensitive layer if necessary.

As described above, the light-scattering subbing layer and the light-absorbing subbing layer are layers intended to prevent light interference in a photoreceptor for a printer. The light-scattering undercoat layer is composed of a conductive powder such as tin oxide or antimony oxide and a white pigment such as zinc oxide, zinc sulfide, titanium oxide, etc. dispersed in a thermosetting resin as shown below. The light-absorbing subbing layer is constructed by dispersing a conductive light-absorbing pigment such as carbon, various metals, and/or a light-absorbing organic pigment in a similar thermosetting resin. The thermosetting resin used here includes, for example, active hydrogen (-OH group, -
Compounds containing multiple hydrogen groups such as N11□ groups and -N11 groups; compounds containing multiple isocyanate groups; and/or
Alternatively, it is thermally polymerized with a compound containing a plurality of epoxy groups. Examples of compounds containing multiple active hydrogens include polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester 2 polyethylene glycol, polypropylene glycol, polybutylene glycol, and droxyethyl methacrylate groups. Examples include acrylic resins.

Examples of compounds containing multiple isocyanate groups include tolylene diisocyanate.

Examples include hexamethylene diisocyanate, diphenylmethane diisocyanate, and prepolymers thereof, and examples of compounds having a plurality of epoxy groups include bisphenol A type epoxy resin.

In any case, the light-scattering or light-absorbing undercoat layer is prepared by coating a liquid in which the above-mentioned components are dissolved or dispersed on the substrate.
It is formed by thermal polymerization at -200°C. The thickness of this undercoat layer is suitably 1 to 10 .mu.m. The weight ratio of the conductive powder, white pigment, and thermosetting resin is 2 to 6/l-
The weight ratio of the light-absorbing pigment to the thermosetting resin is preferably 4 to 9/1 to 6.

〔effect〕

Since the electrophotographic photoreceptor of the present invention has a layer in which a charge generating substance is dispersed and is composed of a charge generating substance and a polyethylene glycol mono- or diester, it has high sensitivity and significantly reduces chargeability due to pre-exposure fatigue. It's small, and even when it comes to repeating the electric current and exposure, the band f! ! It has the remarkable effect that the potential does not drop.

〔Example〕

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

Example 1 [Coating liquid for charge generation layer] 5 parts by weight of the azo pigment (pigment NQI) shown in Table 1 and stearic acid monoester of polyethylene glycol [Ionet MS-400, Sanyo Chemical Co., Ltd.] (7) 0 A pigment dispersion was obtained by mixing with 160 parts by weight of a 39% by weight cyclohexanone solution in a ball mill for 72 hours, and then 90 parts by weight of methyl ethyl ketone was further mixed with 100 parts by weight of this pigment dispersion while stirring to form a charge generation layer. It was used as a coating liquid.

[Coating liquid for charge transfer layer]

100 parts by weight of an α-phenylstilbene charge transfer substance (compound below) 800 parts by weight tetrahydrofuran Next, the above coating solution for the charge generation layer was coated with a blade onto a 75 μm polyester film substrate on which AQ had been vacuum-deposited. ,
It was heated and dried at 120° C. for 10 minutes to form a charge generation layer with a thickness of about 0.2 μm. Next, the charge of the above composition is transferred onto the charge generation layer! ! Coating solution for layer 11 was applied with a blade at 120°C.
The photoreceptor was then dried by heating for 20 minutes to form a charge transfer layer of about 20 μm.

Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that the azo pigment in the charge generation layer coating solution was replaced with pigment Nα39.

Example 3 Ionet MS400 of Example 1 was replaced with stearic acid diester of polyethylene glycol [Ionet DS400
A photoreceptor was prepared in the same manner as in Example 1, except that the photoreceptor was replaced with the photoreceptor (manufactured by Sanyo Kasei Co., Ltd.).

Example 4 A photoreceptor was produced in the same manner as in Example 3 except that the azo pigment in Example 3 was replaced with an azo pigment (Na39).

Example 5 The charge transfer layer coating solution used in Example 1 was applied to a 75μ polyester film substrate on which AQ was vacuum-deposited in Example 1.
Apply blade coating in the same manner as above, then dry to about 20μ
A charge transfer layer of m was formed. Next, the coating solution for charge generation layer used in Example 1 was spray coated onto this charge transfer layer, and dried by heating at 120° C. for 30 minutes to form a charge generation layer of about 0.2 μm. It was created.

Example 6 A photoreceptor was prepared in the same manner as in Example 5, except that the charge generation layer coating liquid was replaced with that of Example 3.

Example 7 A photoreceptor was produced in the same manner as in Example 1, except that the α-phenylstilbene compound in the charge transfer layer coating solution was changed to a compound having the structure below.

Example 8 A photoreceptor was prepared in the same manner as in Example 3 except that the charge generation layer coating liquid in Example 7 was replaced with that in Example 3.

Example 9 The same procedure as in Example 2 was carried out except that Ionet MS400, which was a component of the coating liquid for the charge generation layer in Example 2, was replaced with another stearic acid monoester of polyethylene glycol (Ionet MSiooo, manufactured by Sanyo Kasei Co., Ltd.). A photoreceptor was prepared.

Example 10 Ionet DS400, the coating liquid component for the charge generation layer in Example 4, was replaced with lauric acid diester of polyethylene glycol [Ionet DL200, Sanyo Chemical Co., Ltd.]
A photoreceptor was produced in the same manner as in Example 4 except that .

Example 11 Fine powder of tin oxide containing 10 parts by weight of antimony oxide by 8 parts
1 part by weight, 5 parts by weight of titanium oxide white pigment powder, and 1 part by weight of polyvinyl butyral (trade name: nL-1, manufactured by Block Chemical Co., Ltd.)
68 parts by weight of a 2% by weight methyl ethyl ketone solution was ball milled for 72 hours, then 47 parts by weight of methyl ethyl ketone was added and the mixture was ball milled again for 48 hours. Next, 80 parts by weight of this pigment dispersion was further mixed with a solution of 8 parts by weight of tolylene diisocyanate in 20 deuterium methyl ethyl ketone while stirring to obtain a light scattering undercoat layer coating solution.

Next, the light scattering undercoat layer coating solution was coated with a blade on a 75 μm polyester film substrate on which AQ was vacuum-deposited, and the light scattering undercoat layer was cured by heating at 120° C. for 30 minutes. formed a layer.

Next, a photoreceptor was prepared in which a charge generation layer and a charge transfer layer were formed on this light scattering undercoat layer in the same manner as in Example 2.

Example 12 A photoreceptor was prepared in the same manner as in Example 11, except that the charge generation layer coating liquid was replaced with that of Example 4.

Comparative Examples 1 to 2 Polyvinyl butyral (trade name: XYI
Photoreceptors were prepared in the same manner as in Examples 1 and 2, except that a pigment dispersion was prepared using a 0.78% by weight solution of polyvinyl butyral.

Comparative Example 3 Same as Example 5 except that polyvinyl butyral (trade name: A photoreceptor was prepared.

Comparative Example 4 The same procedure as in Example 7 was carried out except that polyvinyl butyral (trade name: XYIIL, Union Carbide Plastics Co., Ltd. II) was used as the polyethylene glycol stearate ester in the coating solution for the charge generation layer as in Comparative Examples 1 and 2. A photoreceptor was created.

Comparative Example 5 A photoreceptor was prepared in the same manner as in Example 2, except that polyester (trade name: Vylon 200, manufactured by Toyobo Co., Ltd.) was used as the polyethylene glycol stearate ester in the coating solution for the charge generation layer, as in Comparative Examples 1 and 2. It was created.

Comparative Example 6 A 0.78 weight, 1% cyclohexanone solution of polyethylene glycol stearate was mixed with a 5.88 weight piece of polyvinyl butyral (trade name: %
A photoreceptor was prepared in the same manner as in Example 1 except that a cyclohexanone solution was used.

Comparative Example 7 A photoreceptor was prepared in the same manner as in Example 2 except that tristearyl phosphate was used instead of polyethylene glycol stearate when preparing the coating solution for the charge generation layer.

Comparative Examples 8 to 9 Examples except that 90 parts by weight of methyl ethyl ketone used in preparing the coating solution for the charge generation layer was replaced with 90 parts by weight of a 4-weight methyl ethyl ketone solution of polyester resin (trade name: Pylon 200, manufactured by Toyobo Co., Ltd.) Photoreceptors were prepared in the same manner as in Examples 9 and 10.

The electrophotographic properties of the electrophotographic photoreceptor prepared as described above were evaluated as follows using an electrostatic copying paper test bag Fj (Kawaguchi Electric Seisakusho ■, model SP 428). First, a corona discharge of 16 KV is applied to each photoreceptor for 20 seconds, during which Φ charging potential V, (vol.
t), then discharge in the dark until the surface potential is 18
When the voltage reaches 00V, tungsten light is irradiated to reduce the exposure amount 5 (l) necessary for the surface potential to optically attenuate to -400V.
ux 5ee) was calculated. Then color temperature 2856'
After irradiation with K tungsten light at 100000 lux see, the JtF electric potential Vt after photo-fatigue was determined again in the same manner as above.
'(volt) and exposure is' (lux 5ec)
I asked for The above results are shown in Table-1.

For the type photoreceptor shown in Figure 2, corona discharge of +7KV is performed for 20 seconds, during which time ? Il
'Measure the electric potential v2, then leave it in a dark place, and when the surface potential reaches +800V, irradiate it with tungsten light, and the exposure amount S required to attenuate the surface potential to +400V.
I asked for After that, 1000001ux s as above
Charge 4th position V21 and exposure amount S' after ec irradiation and photo fatigue
I asked for

[Brief explanation of the drawing]

1 to 3 are schematic cross-sectional views of various electrophotographic photoreceptors according to the present invention. 1; Charge generation layer 2; Charge transfer layer 3; Conductive support 4; Undercoat layer

Claims (1)

[Claims] (1) An electrophotographic photoreceptor having at least a layer in which a charge-generating substance is dispersed on a conductive support, characterized in that the layer in which the charge-generating substance is dispersed is composed of a charge-generating substance and a mono- or diester of polyethylene glycol. A photoreceptor for electrophotography.