JPS63197960A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the rise of residual potential and to stabilize electric characteristics by incorporating a specified azo pigment in an interlayer. CONSTITUTION:An electrophotographic sensitive body is obtained by successively laminating on a conductive substrate the interlayer, an electric charge generating layer, and a charge transfer layer, and the interlayer contains at least one of the azo pigments represented by formula I in which A is one of groups represented by formula II in which X is an optionally substituted aromatic ring; Ar1 is an optionally substituted benzene ring; and R1 is H, thus permitting rise of residual potential to be prevented, and stable electric characteristics to be retained even when environmental conditions, such as temperature and humidity, vary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in an electrophotographic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transfer layer are successively laminated on a conductive substrate.

[Prior art]

A photoreceptor formed from a charge generation layer and a charge transfer layer is provided on a conductive substrate, and then a corona is applied to the photoreceptor.

After being uniformly charged with a charger and imagewise exposed to form an electrostatic latent image corresponding to optical information on the surface of the photoreceptor, when developed with a developer containing charged and colored particles (toner), a speckled image is formed. Abnormal images occur. When the charge polarity of the toner is opposite to the charge polarity of the photoconductor (regular development), the toner-adhered area of the image (in the case of black-and-white development, the area corresponding to the so-called solid black area) is coated with a number of 1 to 0. If a patchy white spot (called a white spot) of about 1 mm occurs, and the charge polarity of the toner is the same as the charged polarity (reverse development), the toner-free area of the image (corresponding to the so-called background area) occurs. part) 0.1 to several ■■
Some degree of spot-like abnormal images, so-called background stains, occur.

These spot-like abnormal images occur when the photoreceptor is repeatedly subjected to the image forming process of charging, exposing, developing, and transferring, and as the image forming process is repeated, the density of the spots increases and their size tends to increase. . Furthermore, depending on the photoreceptor, the problem may occur from the beginning of image formation.

These spot-like abnormal images significantly impair copy quality and print quality in electrophotographic copiers, printers, and facsimile machines.

This abnormal image occurs because when the photoreceptor is charged with a corona or charger, charges are locally injected from the chargeable substrate into the photosensitive layer, resulting in the existence of local low potential areas on the surface of the photosensitive layer, which prevents development. This is based on the fact that non-uniformity occurs. Therefore, it has been proposed to provide an intermediate layer between the conductive layer and the charge generation layer for the purpose of preventing charge injection.

For example, JP-A Nos. 47-6341, 48-3544 and 48-12034 have cellulose sulfate resin intermediate layers; No. 58-9
No. 5351, No. 58-98739 and No. 60-6625
No. 8 has a nylon resin intermediate layer, as disclosed in Japanese Patent Application Laid-open No. 48-261.
No. 41 has a vinyl acetate resin intermediate layer, as disclosed in JP-A-49-6.
No. 9332 and No. 52-10138 disclose a maleic acid resin intermediate layer, and JP-A-58-103155 discloses a polyvinyl alcohol resin intermediate layer.

A photoreceptor using such an intermediate layer produces fewer spot-like abnormal images than a photoreceptor without an intermediate layer, and the intermediate layer is effective. However, the intermediate layer reduces the sensitivity of the photoreceptor, and as the image forming process is repeated, the residual potential gradually increases. In addition, the resin intermediate layer is easily affected by moisture in the air, and the residual potential becomes particularly high at low temperatures and low humidity. There was a problem in that it caused dirt.

〔the purpose〕

The present invention provides an electrophotographic photoreceptor that does not have an increase in residual potential, exhibits stable electrical characteristics even when the environment such as temperature and humidity fluctuates, and does not cause spot-like abnormal images or background stains. The purpose is to

〔composition〕

According to the present invention, in an electrophotographic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transfer layer are sequentially laminated on a conductive substrate, the intermediate layer is made of an azo pigment represented by the following general formula (1). Provided is an electrophotographic photoreceptor characterized by being made of a thermosetting resin containing at least one type of thermosetting resin.

(However, in Equation 1 (1), ^ is.

・1,X,! In the group represented by, X is a benzene ring and its substituted product, Ar1 is a benzene ring and its substituted product, and R□ is hydrogen. ) The present inventors have conducted extensive studies on an electrophotographic photoreceptor that can suppress the occurrence of spot-like abnormal images by increasing the charging property, and can also reduce the residual potential to prevent background smearing. It was discovered that an electrophotographic photoreceptor suitable for the above purpose can be obtained when a thermosetting resin containing at least one azo pigment represented by the general formula (I) is used, and the present invention was completed. I came to the conclusion.

In conventional electrophotographic photoreceptors, by increasing the thickness of the intermediate layer, charging performance can be increased and the formation of spot-like abnormal images can be suppressed, but due to repeated charging and exposure, the residual potential increases significantly. , stains appear on the skin. On the other hand, if the thickness of the intermediate layer is made thinner, it is possible to suppress the increase in the residual potential, but in this case, the charging property decreases and a spot-like abnormal image occurs. No material has been found that simultaneously satisfies these two characteristics.

In addition, the conventional photoreceptor has the drawback that the residual potential increases significantly under low temperature and low humidity conditions, and the photoreceptor characteristics fluctuate due to environmental changes.However, the electrophotographic photoreceptor according to the present invention As shown, even if the environment changes, it is possible to provide a good copy image without spotty white spots or background stains.

The present invention will be explained in more detail below.

The electrophotographic photoreceptor according to the present invention is formed by sequentially laminating an intermediate layer, a charge generation layer, and a charge transfer layer on a conductive substrate.

The purpose of the conductive substrate is to supply charges of opposite polarity to the charged charges to the substrate side.

It is possible to use a material that has an electrical resistance of 101 Ωcm or less and can withstand the film forming conditions for the intermediate layer, charge generation, and charge transfer layer. Examples of these are AQ, Ni
, Cr, Zn, stainless steel, and other electrically conductive metals and alloys, as well as inorganic insulating materials such as glass and ceramics, and polyester and polyimide.

Electrical coatings such as An, Ni, Cr, Zn, stainless steel, carbon, SnO, In, Oa, etc. can be applied to the surface of organic insulating materials such as phenol resin, nylon resin, and paper by methods such as vacuum evaporation, sputtering, and spray painting. Examples include those coated with a conductive substance and subjected to conductive treatment.

The intermediate layer may contain a disazo pigment represented by the above general formula (1) in a dispersed state in a binding resin. Examples of the binding resin include polyester resin, polystyrene resin, polycarbonate resin, polyacrylate resin, and polyvinyl butyral. resin, thermoplastic resin such as polyvinyl acetate resin, ethyl cellulose resin, polysulfone resin, polyvinyl carbazole resin, etc. can be used, but when overcoating the charge generation layer and charge transport layer on the intermediate layer, May melt and cause coating defects. For this reason, it is more preferable to use a thermosetting resin as shown below as the binder resin.

Thermosetting resins include 1, for example, active hydrogen (-〇H group, -NH group).

It is obtained by thermally polymerizing a compound containing a plurality of hydrogen groups such as -NH group and a compound containing a plurality of isocyanate groups and/or a compound containing a plurality of epoxy groups. Compounds containing multiple active hydrogens include:
Examples of the compound include polyvinyl butyral, phenoxy resin, phenol resin, polyamide, acrylic resin containing active hydrogen such as hydroxyethyl methacrylate group, and examples of the compound containing a plurality of isocyanate groups.

Examples include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and their prepolymers, and compounds containing multiple epoxy groups include bisphenol A.
Examples include molded epoxy resin.

In the present invention, the bisazo pigment represented by the general formula (1) is used, and its content is from 3 parts by weight to 100 parts by weight, preferably 5 parts by weight, based on 10 parts by weight of the resin.
50 parts by weight.

Dispersion methods for disazo pigments in resin include ball mill,
Ultrasonic methods, three rolls, sand gliders, attritors, impellers, stone mills, etc. can be used.

To disperse diazo pigments into thermoplastics.

The pigment may be added to an organic solvent solution of the resin and dispersed by pulverization and mixing using the above-mentioned dispersion means. However, when dispersing the disazo pigment in a thermosetting resin, first add the disazo pigment to an organic solvent solution of a compound containing active hydrogen. After the inocyanate group is dispersed therein, a compound containing a plurality of incyanate groups and/or a compound containing a plurality of epoxy resins is added. This is to avoid thermal polymerization in the first dispersion step, since the first dispersion step is accompanied by heat generation. The intermediate layer is formed on the conductive substrate by a conventionally known coating method such as roll coating, dip coating, spray coating, or blade coating. thermally polymerize with
Film thickness 0.1 μm--10 μm (preferably 0.5 μm to 5 μm
(μugly) as the middle layer.

Next, specific examples of the compound represented by the general formula (1) used in the present invention are shown below.

The charge generation layer is a layer whose purpose is to generate and separate charges by imagewise exposure. In the present invention, the charge generation layer uses an organic dye/pigment, crystalline selenium, or arsenic selenide as a charge generation substance, and examples of the organic pigment include a phthalocyanine pigment, a disazo raw material, a trisazo pigment, a perylene pigment, Examples include squalic basic dyes, azulenium salt dyes, and quinone fused polycyclic compounds. Specific examples of disazo pigments and trisazo pigments are shown below.

ILMUQ -Episode 11-J Rainbow House--Ko [-111 unit
--1he111-JLnu
-1-Δ-11 face Jib -1 person 111" Lnu -1-to---face JL--1-Δ-111 and length -11 111"L limb -1-Δ---Group" Ll
−6= face i n face] 1st sentence −−1Δ−−−face” L correct
-11Δ---face JL Shin
-11 to 111-JL encouragement--
com face'L--11 to 111-JL encouragement-1111-J[large
-Each person---face" L
-11 Δ-1-1 and h -com Face 4L and -11 to111 These organic dyes and pigments can be prepared by adding an organic solvent in a resin or without a resin and using the above methods such as ball milling. Disperse and use in the same way. Examples of resins for dispersing these organic dyes and pigments include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polycarbonate, and polyether, as well as polystyrene, polyacrylate, polymethacrylate, poly-N-vinylcarbazole, polyvinyl butyral, and styrene. Examples include polymers and copolymers such as -butadiene copolymer and styrene-acrylonitrile copolymer, which require insulation and adhesive properties. A charge generating layer having a thickness of 0.05 .mu.m to several .mu.m is formed by dispersing using the same dispersion means as for the intermediate layer, and forming and drying the film on the intermediate layer in the same manner.

The content of the organic dye and pigment is preferably 60 to 100 weight.

The purpose of the charge transfer layer provided on the charge generation layer is to retain the charged charges on its surface, and also to move the charges generated and separated in the charge generation layer by exposure and combine them with the held charges. This is the layer where In order to achieve the purpose of retaining electrical charges, high electrical resistance is required.
In addition, in order to achieve the purpose of obtaining a high surface potential using the retained charges, it is required that the dielectric constant be small and the charge mobility be good. In order to satisfy these requirements, an organic charge transfer layer containing an organic charge transfer substance as an active ingredient is used. Examples of organic charge transfer substances include:
Poly-N-vinylcarbazole compounds, pyrazoline compounds, α-phenylstyrene bene compounds, hydrazone compounds, diarylmethane compounds, triphenylamine compounds, divinylbenzene compounds, fluorine compounds, anthracene compounds, Conventionally known compounds such as oxadiazole compounds and diaminocarbazole compounds can be used.

These organic charge transfer substances other than polymers such as polyvinylcarbazole are used by being blended with the same resin as shown as the binder for the charge generation layer described above. However, it is not necessary that the resin used in the charge generation layer and the resin used in the charge transfer layer be the same, and a plasticizer may be added to them if necessary. Examples of such plasticizers include halogenated paraffins, dimethylnaphthalene, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and copolymers of polymers such as polyester. A charge transfer substance, the binder resin, and silicone oil (as a leveling agent during film formation) are dissolved in an organic solvent, and a film is formed and dried in the same manner as the intermediate layer and the charge generation layer.

5 μl to 100 μl of the peritoneal charge transport layer is formed on the charge generating layer. The charge transfer material to resin binder ratio is 2/8 to 8/2 weight ratio, and the amount of silicone oil to resin binder is 0.001% by weight to 1 weight ratio.

〔effect〕

Since the electrophotographic photoreceptor of the present invention uses a thermosetting resin containing at least one kind of azo pigment represented by the general formula (1) as the intermediate layer, there is no increase in residual potential;
Furthermore, it exhibits stable electrical characteristics even when the environment such as temperature and humidity fluctuates, and provides highly reliable copied images that do not cause spot-like abnormal images or background stains.

〔Example〕

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

Example 1 Alumina sintered balls with a diameter of 10 and a volume of 172 were placed in a 120 mm glass pot, and 120 g of the following resin solution A and 0.5 g of an azo pigment (azo pigment No. for intermediate layer) were added to a 120 mm glass pot.
1)-1) and 100 g of methyl ethyl ketone were added and mixed for 72 hours. After 220 g of methyl ethyl ketone was added and mixed for 24 hours, 27 g of the following TDI solution and 240 g of methyl ethyl ketone were added to 420 g of this dispersion to prepare an intermediate layer coating solution.

[Resin liquid A]

Cyclohexanone 92 parts by weight (TD
Solution I] Tolylene diisocyanate 10 parts by weight Methyl ethyl ketone 90 parts by weight Next, φ15
In a cm glass pot, a volume of 172 φ1c stainless steel pole and 400g of cyclohexanone and 25
Add g of azo pigment (Nol) for charge generation material and
Mixed for 8 hours.

After adding an additional 40g of cyclohexanone and mixing for another 24 hours, 800g of the dispersion solution was taken out.
While stirring, 800 g of tetrahydrofuran was added dropwise to obtain a charge generation layer coating solution.

The above intermediate layer coating solution was applied by dip coating onto an aluminum drum with a wall thickness of 2 mm and 80 φ x 340 mm, and then heated and cured at 130° C. for 1 hour to form an intermediate layer with a thickness of 2 μm. The aluminum drum on which the intermediate layer was formed was immersed in the above charge generation layer coating solution, pulled up at a rate of 15 mm/sec to perform dip coating, and then dried at 130° C. for 10 minutes to form a charge generation layer. Further, a charge transfer layer coating solution shown below was applied thereon by dip coating, and then dried at 130 DEG C. for 1 hour to form a charge transfer layer of 20 .mu.m.

[Charge transfer layer coating liquid (composed of the following composition)] α-
Phenylstilbene-based charge transfer substance Compounds below) (Product name: Valalite (1:1400: Teijin)) Tetrahydrofuran 80 parts by weight The photoreceptor drum thus prepared was charged, the transfer charger and the developing bias were set to negative polarity. When the image was evaluated by installing it on an improved FT4060 (■Ricoh copier) and developing it with a developer for %FT8030 (■Ricoh copier), a clear image was obtained with no speckled white spots in the solid black areas. It was done.

Further, the photoreceptor was subjected to forced fatigue by repeating exposure and charging 1000 times, and then developed and evaluated the image. As a result, an image was obtained without a single white spot or stain on the background.

In addition, this photoreceptor was subjected to initial image, charging and exposure cycles 1000 times in the same manner as above in an environment of 10° C. and 15% RH.
When the images were evaluated after repeated use, it was found that there were no mottled white spots and no background stains.

Comparative Example 1 The charge generation layer and charge transfer layer liquid shown in Example 1 were coated in the same manner as in Example 1 without providing an intermediate layer on an aluminum drum with a wall thickness of 2 m, 80φ x 340mm length, and a photoreceptor was formed. Created.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the following resin liquid B was used instead of the intermediate layer in Example 1 and was dip coated and cured by heating at 130° C. for 1 hour to obtain a 2 μ hazy intermediate layer. It was created.

[Resin liquid B]

Tolylene diisocyanate (TDI) 14.5 parts by weight Cyclohexane 552 parts by weight Methyl ethyl ketone 130 parts by weight Example 2 The azo pigment for the intermediate layer of Example 1 was used as the azo pigment for the intermediate layer No. (1)-2 exemplified in Table 1. A photoreceptor was produced in the same manner as in Example 1 except that

Example 3 A photoreceptor was produced in the same manner as in Example 1, except that the azo pigment for intermediate layer No. (1)-5 exemplified in Table 1 was used as the azo pigment for intermediate layer of Example 1.

Example 4 A photoreceptor was produced in the same manner as in Example 1, except that the azo pigment for intermediate layer No. (1)-6 exemplified in Table 1 was used as the azo pigment for intermediate layer of Example 1.

Example 5 The same intermediate layer coating solution as in Example 1 was applied by dip coating onto an aluminum drum having a wall thickness of 2 mm, a diameter of 80 mm and a length of 340 mm.

The material was cured by heating at 130° C. for 1 hour to form an intermediate layer having a thickness of 2 μm.

In addition, in a glass pot with a diameter of 15 cm, 1 of the volume of 172
Add 0+mmφ agate ball, add 400g of resin liquid C below and 25g of azo pigment (No. 39) for charge generating material.
) and mixed for 48 hours. Further, 580 g of resin liquid C was added and mixed for another 24 hours, and then 710 g of methyl ethyl ketone was added dropwise to 950 g of the dispersion solution taken out while stirring to obtain a charge generation layer coating solution.

The aluminum drum provided with the above-mentioned intermediate layer was immersed in this charge generation layer coating solution, pulled up at a speed of 6 seconds per second, and then heated and dried at 130°C for 10 minutes to form a charge generation layer. did.

Next, the charge transfer layer coating solution shown in Example 1 was applied by dip coating in the same manner as in Example 1, and a 20 g charge transfer layer was provided to prepare a photoreceptor.

[Resin liquid C]

Cyclohexane 970 parts by weight Example 6 Example 5 except that the intermediate layer azo pigment No. (1)-12 illustrated in Table 1 was used instead of the intermediate layer azo pigment of Example 5.
A photoreceptor similar to that was created.

Comparative Example 3 A photoconductor was produced in the same manner as in Example 5, except that instead of the intermediate layer in Example 5, the following resin liquid (D) was applied and heated at 130° C. for 10 minutes to form a 2 μm intermediate layer. did.

[Resin liquid D]

Nylon resin (manufactured by Toshisha) 8 parts by weight methanol 60 parts by weight butanol
32 parts by weight The photoreceptor thus prepared was tested at room temperature (22°C to 25°C, 50% RH to 65% RH) using the modified copying test apparatus shown in Example 1.
), image evaluation was performed in the same manner as in Example 1 under a low temperature, low humidity (10° C., 15% RH) environment.

The results are shown in Tables 2 and 3. It can be seen that the photoreceptor of the present invention provides stable copied images free of speckled white spots and background smearing despite environmental changes.

The meaning of each symbol in the table is as follows.

0: Abnormal images do not occur Δ: Abnormal images occur, but the degree is slight and there is no substantial problem X: Abnormal images occur severely ℃
, 55% to 65%) Procedural amendment (voluntary) December 12, 1988 Director General of the Patent Office Kunio Ogawa 1. Indication of the case 1988 Patent Application No. 29394 2. Name of the invention Electronic photograph Photoconductor 3, Relationship with the case of the person making the amendment Patent applicant address: 1-3-6 Nakamagome, Ota-ku, Tokyo Name
(674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 Address 1-58-1o-5, Yoyogi, Shibuya-ku, Tokyo
Date of amendment order Voluntary 6, Number of inventions increased by amendment 07, Subject of amendment 8. Contents of amendment amended to "Photoconductor provided with a photosensitive layer."

(3) "Corona, Charger" on page 2, lines 9 and 10.

Corrected to "Corona Charger".

(4) “Charged” in line 12 of page 2 is replaced with “charged”
I will correct it.

(5) “Several ■ to 0.1 tumors” on page 2, line 17,
Correct it to "rO, 1-~number-".

(6) “Corona, Charger” on page 3, line 11,
Corrected to "Corona Charger".

(7) Correct "cellulose sulfate" in line 19 of page 3 to "cellulose nitrate."

(8) On page 4, line 5, "JP-A-58-103155J" is corrected to "JP-A-58-105155."

To do.

(10) Correct "conductive substrate" in line 6 of page 7 to "conductive substrate."

(11) Correct "and" in line 16 of page 7 to "and".

(12) Pigment No. on page 34, line 2 to line 9 from the bottom,
Correct the structural formulas 72 to 74 as shown below.

(14) No. 37
Corrected to ``rlO, 5g no 7zo pigment''.

(15) Change “Add /” to “Add /” on page 38, line 5.
I will correct it.

(16) Correct "cyclohexane" in line 9 of page 43 to "cyclohexanone."

(17) “Nylon resin (manufactured by Toshisha)” at the end of page 43
is corrected to [Nylon resin (C manufactured by Toshisha Co., Ltd.) l-8000)J.

"Claim (1) An electrophotographic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transfer layer are sequentially laminated on a conductive substrate, wherein the intermediate layer is an azozoic acid compound represented by the following general formula (1). An electrophotographic photoreceptor characterized by containing at least one pigment.

(However, in formula (I), A is a group represented by the following, X is a benzene ring and its substituted product, Ar1 is a benzene ring and its substituted product, and R1 is hydrogen.)

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor in which an intermediate layer, a charge generation layer, and a charge transfer layer are sequentially laminated on a conductive substrate, the intermediate layer contains at least one azo pigment represented by the following general formula (I). An electrophotographic photoreceptor comprising a thermosetting resin containing seeds. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (However, in formula (I), A is a group represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and X is a benzene ring and its substitution Ar_1 is a benzene ring and its substituted product, R_
2 is hydrogen. )