JPH04170553A - Electrophotosensitive material - Google Patents

Abstract

PURPOSE:To obtain an electrophotosensitive material, which can hold a picture of high quality without accumulation of residual potential in a repeated electrophotographic process, by containing polyamide resin of containing a specific unit component in an intermediate layer. CONSTITUTION:An intermediate layer contains polyamide resin having a unit component expressed by a formula I. In the formula I, R1 represents a substituted or not alkyl group, R2 a substituted or not alkylene group, and (n) an integer of 1 or more. Here by containing denatured polyamide resin in the intermediate layer between a sensitive layer and a surface protective layer, the intermediate layer acts as a barrier layer of the sensitive layer, at the time of molding the protective layer, and further as an adhesive layer between the sensitive layer and the protective layer after molding the protective layer. In this way, a picture of high quality without a sunspot-shaded picture defect (black dot) and fogging can be held with stable sensitivity and no accumulation of residual potential in a repeated eletrophotographic process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and particularly to an intermediate layer when a protective layer is used.

[Prior Art] Electrophotographic photoreceptors are required to have the required sensitivity, electrical properties, and optical properties according to the electrophotographic process used. Since electrical and mechanical external forces such as corona charging, toner development, transfer to transfer paper, and cleaning treatment are directly applied to the surface layer of the photoreceptor, durability against these forces is required. Specifically, durability is required against surface friction and scratches caused by rubbing, as well as surface deterioration due to ozone generated during corona charging.

On the other hand, there is also a problem of toner adhesion to the surface layer due to repeated toner development and cleaning, and to solve this problem, it is desired to improve the cleaning properties of the surface layer.

In particular, in the case of positively charging photoreceptors, the layer in the photosensitive layer that is most isolated from the conductive support is the charge generation layer, so the surface layer is mechanically and chemically weak, making it difficult to provide a protective layer. Very effective in terms of durability. In order to satisfy the characteristics required of the surface layer as described above, attempts have been made to provide a surface protective layer containing resin as a main component. For example, JP-A-5
7-30843, a protective layer in which resistance is controlled by adding a metal oxide as a conductive powder has been proposed.

However, the conventional methods have problems with the dispersibility and aggregation of metal oxide particles in the yt4 fat pile, conductivity and transparency when used in the protective layer, and non-uniformity of the surface of the protective layer. , image defects due to unevenness, increased residual potential due to repeated charging, and decreased sensitivity were likely to occur.

Furthermore, when a protective layer is laminated on top of a photosensitive layer for positive charging, which has a charge transport layer and a charge/generation layer laminated in this order on a support, the problem often arises that the sensitivity is greatly reduced. , which was a hindrance to practical application.

[Problem to be solved by the invention]

The present invention seeks to provide an electrophotographic photoreceptor that meets the above-mentioned requirements. That is, the object of the present invention is to provide an electronic device having an intermediate layer that allows a protective layer with excellent slipperiness and durability against surface abrasion and scratches caused by rubbing to be coated without damaging the photosensitive layer. An object of the present invention is to provide a photographic photoreceptor.

Still another object of the present invention is to provide an electrophotographic photoreceptor that does not accumulate residual potential and can maintain high image quality in repeated electrophotographic processes. Still another object of the present invention is to provide an electrophotographic photoreceptor that is free from image defects such as black dots (hereinafter referred to as black dots) and is capable of producing fog-free images.

[Means to solve the problem]

That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer, an intermediate layer, and a protective layer in this order on a conductive support, in which the intermediate layer comprises a polyamide resin having a unit component represented by the following general formula (1). An electrophotographic photoreceptor characterized by containing the general formula (I) ), and an electrophotographic apparatus and facsimile equipped with the photoreceptor.

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

In the general formula (I), examples of the alkyl group represented by Rt include methyl group, ethyl group, propyl group, etc., and examples of the alkylene group represented by R2 include methylene group, ethylene group, propylene group, isopropylene group, etc. can be mentioned. These alkyl groups and alkylene groups may have a substituent such as a halogen atom, an aryl group such as a phenyl group, or an alkoxy group.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photosensitive layer, an intermediate layer, and a protective layer on a conductive support.

The protective layer will be explained below.

In the protective layer of an electrophotographic photoreceptor, it is essential to control the resistance in relation to chargeability, residual potential, sensitivity, etc. For this reason, attempts have been made in the past to control resistance by dispersing metal oxides in a binder resin in a protective layer. - When particles are dispersed in a protective layer for boat fishing, in order to prevent scattering of incident light by the dispersed particles, the particle size of the particles must be smaller than the wavelength of the incident light, that is, ultrafine particles of 0.3μ or less. It is necessary that there be.

Examples of the resin used in the protective layer in the present invention include resins such as polycarbonate, polyester, phenol resin, polyethylene terephthalate, acrylic resin, polystyrene, cellulose, polyethylene, polypropylene, polyurethane, epoxy, silicone, and polyvinyl chloride.

The present inventors investigated how to satisfy all the characteristics of dispersibility, abrasion resistance, and scratch resistance of these fine particles, and found that a resin containing a monomer having a curable ethylenic double bond, especially an acrylic monomer, was used with metal. It was found that the dispersibility of the fine particles, abrasion resistance, and scratch resistance are excellent when ultrafine oxide particles are dispersed.

The conductive metal oxide used in the present invention includes zinc oxide,
titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide,
Ultrafine particles of tin oxide, zirconium oxide, etc. doped with antimony can be used. These metal oxides may be used alone or in combination of two or more. When two or more types are mixed, they may be in the form of a solid solution or fusion.

The above-mentioned curable acrylic monomer has the following general formula [1]
It is a compound with an acrylic functional group shown in the figure below.

HOCCH=CHz IROCC=CHz These acrylic monomers may be used alone or in combination with other commercially available monomers such as polyesters, polycarbonates, polystyrene, cellulose, polyethylene, polypropylene, -polyurethanes, acrylics, epoxies, silicones, polyvinyl chloride, etc. May be mixed with resin.

In the present invention, additives such as a coupling agent and an antioxidant may be added to the protective layer for the purpose of improving dispersibility, binding properties, and weather resistance. The protective layer is formed by applying and curing a solution in which a metal oxide is dispersed in the binder resin.

However, while a protective layer made of a resin containing a curable acrylic monomer, for example, satisfies both the dispersibility of the fine particles and the abrasion and scratch resistance characteristics, when it is formed on the photosensitive layer, it corrodes the photoreceptor and increases the sensitivity. It has been found that there is a drawback in that it causes deterioration.

This deterioration in sensitivity was particularly noticeable in positively charging photoreceptors having a charge generation layer as an upper layer.

As a method for dealing with this problem, the present inventors discovered that it is effective to provide an intermediate layer between the photosensitive layer and the protective layer, and established an optimal formulation for the intermediate layer.

Therefore, the middle layer will be explained below.

The intermediate layer of the present invention is characterized by using a modified polyamide resin having a unit component represented by the general formula (I), in which the hydrogen atoms of the amide groups of the polyamide resin are replaced by a substitution reaction.

The polyamide resin constituting the main chain of the modified polyamide used in the present invention is 6.11, 12°66.610
and copolymerized nylon resins containing the above components; N-alkoxymethylated and N-alkylated nylon resins; and nylon resins containing aromatic components.

Further, the modified polyamide used in the present invention can also be crosslinked in consideration of solvent resistance to the coating material for the photosensitive layer. Crosslinking is usually carried out using an epoxy compound, a melamine compound, etc. by heat treatment after the coating film is formed. When N-alkoxymethylated nylon resin is used as the polyamide component, self-crosslinking is performed by heating using an acid catalyst such as citric acid, adipic acid, tartaric acid, maleic acid, or hypophosphorous acid without using a crosslinking agent. A crosslinked body can also be formed by.

Examples of the main chain component of the polyamide resin used in the present invention include a polymer having a structure such as CHzOCHs as a unit component, or a copolymer having two or more of these structures as a unit component. Specific examples of such main chain components are shown below.

Examples of Components of Polyamide Resin Main Chain Next, examples of modified polyamide resins actually used in the present invention will be shown.

In the electrophotographic photoreceptor of the present invention, by containing the above-mentioned modified polyamide resin in the intermediate layer between the photosensitive layer and the surface protective layer, it acts as a barrier layer for the photosensitive layer when forming the protective layer, and After the protective layer is formed, it acts as an adhesive layer between the photosensitive layer and the protective layer.

Although the reason for the above effects of the modified polyamide resin is not clear, the following structural factors are considered.

(1) By adding side chains, coating films are more easily amorphous and structured than linear polymers, improving film forming properties, and preventing pinhole-like coating defects from occurring even in thin films.

(2) The adhesion of the membrane is improved by the polar group on the side chain.

From the above two points, it is considered that the barrier function of the photosensitive layer during the formation of the protective layer and the adhesive function after the film formation are superior to other polyamide resins.

The modified polyamide used in the present invention can be synthesized by reacting formaldehyde and alcohol with polyamide as a raw material to replace hydrogen in amide groups.

Next, a specific synthesis example of the modified polyamide of the present invention will be shown.

Charcoal 1 (exemplified compound [l]) 50g of 6-nylon resin was mixed with 250g of formic acid and 25g of acetic anhydride.
The mixture was added to 0 g of a mixed solvent and dissolved with stirring.

15 g of formaldehyde and 35 g of 2-methoxyethanol were added to this, heated to 60°C, and reacted for 5 hours.Then, the reaction product solution was cooled to room temperature, poured into acetone 51, and filtered by reprecipitation to produce a white reaction product. I got it. This product was stirred and washed in a large amount of water, and after filtration, the product was heated at 40°C for 10 to 20 seconds.
It was dried under reduced pressure under HH conditions to obtain 50.7 g of methoxyethoxymethylated 6-nylon resin (methoxyethoxymethyl group substitution rate: 31%).

The intermediate layer of the present invention may be composed of the above-mentioned modified polyamide alone, or may be composed of a system in which other resins, additives, and conductive substances are added as necessary.

The structure of the photoconductive layer of the electrophotographic photoreceptor of the present invention is a single layer type containing both a charge generating substance and a charge transporting substance, or a laminated type in which a charge generating layer and a charge transporting layer are laminated on a conductive support. Either.

The laminated type photoreceptor will be explained below.

The laminated type photosensitive layer may have a structure in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support, or a structure in which a charge transport layer and a charge generation layer are laminated in this order on a conductive support.

If the support used in the present invention has conductivity,
Any type of pot may be used, such as a pot made of aluminum, copper, chromium, nickel, zinc, stainless steel, etc., molded into a drum or sheet shape, a plastic film laminated with metal foil of aluminum or copper, aluminum, Examples include plastic films on which indium oxide, tin oxide, etc. are vapor-deposited, and metals, plastic films, and paper on which conductive layers are provided by coating a conductive substance alone or together with a binder resin.

The charge transport layer of the laminated photoreceptor is made of a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene, or phenanthrene in the main chain or side chain; a nitrogen-containing ring compound such as indole, carbazole, oxadiazole, or pyrazoline; It is formed using a coating liquid in which a charge transporting substance such as a hydrazone compound or a styryl compound is dissolved in a resin that has film-forming properties. Examples of resins having such film-forming properties include polyester, polycarbonate, polystyrene, and polymethacrylic acid ester. The thickness of the transport layer is 5 to 40 μm, preferably 10 to 30 μm.

The charge generating layer of the laminated photoreceptor is made of charge generating substances such as quinone pigments such as Sudan red and Guianpuru, quinicyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, phthalocyanine pigments, polyvinyl butyral, polystyrene, polyvinyl acetate, etc. The pigment is formed by dispersing it in a binder resin such as acrylic resin and coating this dispersion, or by vacuum depositing the pigment. The thickness of such a charge generation layer is 5 microns or less, preferably 0.05 to 3 microns.

In the present invention, a subbing layer having barrier and adhesive functions may be provided between the conductive layer and the photosensitive layer. The subbing layer can be formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, alcohol-soluble amide, polyurethane, gelatin, or the like. The appropriate thickness of the undercoat layer is O, ltI steel ~3μ.

As described above, the electrophotographic photoreceptor of the present invention includes a polyamide resin layer having a unit component represented by the general formula (1) as an intermediate layer on the photosensitive layer, and →N-C-)-(I). 0H2→ORz h-OR.

The photoreceptor for electrophotography further has a protective layer formed thereon in which conductive metal oxide ultrafine particles are dispersed in a resin. Therefore, in the present invention, a homogeneous protective layer with high hardness and good dispersibility of conductive fine particles could be formed without damaging the photosensitive layer. As a result, it has become possible to provide an electrophotographic photoreceptor that is free from image defects such as unevenness, fogging, and black spots, has very high wear resistance and scratch resistance, and has good sensitivity.

Furthermore, in the present invention, since there is no deterioration of the photoreceptor due to leaving it under a charged layer, it was possible to provide a photoreceptor without image defects even after repeated durability tests.

FIG. 1 shows a schematic configuration example of a general transfer type electrophotographic apparatus using the electrophotographic photoreceptor of the present invention.

In the figure, reference numeral 1 denotes a drum-type photoreceptor of the present invention as an image carrier, which is rotated at a predetermined circumferential speed in the direction of the arrow around an axis 1a. The photoreceptor 1 is charged by charging means 2 during its rotation process.
The peripheral surface is uniformly charged with a predetermined positive or negative potential, and then exposed to a light image by an image exposure means (not shown) in the exposure section 3 (slit exposure, laser beam scanning exposure, etc.)
receive. As a result, static i1 latent images corresponding to the exposed images are sequentially formed on the circumferential surface of the photoreceptor.

The electrostatic latent image is then developed with toner by a developing means 4, and the toner developed image is transferred by a transfer means 5 from a paper feed section (not shown) between the photoreceptor 1 and the transfer means 5 in synchronization with the rotation of the photoreceptor 1. The images are sequentially transferred onto the surface of the transfer material P that is fed.

The transfer material P that has undergone the image transfer is separated from the photoreceptor surface and introduced into the image fixing means 8, where the image is fixed and a copy is produced.
will be printed out on the outside of the aircraft.

After the image has been transferred, the surface of the photoreceptor 1 is cleaned by a cleaning means 6 to remove residual toner, and is further subjected to a charge removal process by a pre-exposure means 7, and is used repeatedly for image formation.

As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. Also, as the transfer device 5, a corona transfer means is generally widely used.

An electrophotographic apparatus is constructed by combining a plurality of components such as the above-mentioned photoreceptor, developing means, and cleaning means into an apparatus unit, and this unit is configured to be detachable from the apparatus main body. It's okay. For example, the photoreceptor 1 and the cleaning means 6 may be integrated into one device unit, and configured to be detachable using a guide means such as a rail of the device body. At this time, the above-mentioned device unit may include a charging means and/or a developing means.

When using an electrophotographic device as a copying machine or printer, light image exposure involves scanning the reflected light or transmitted light from the original, or reading the original into a signal, and using this signal to scan the laser beam and drive the LED array. , or by driving a liquid crystal shutter array.

When used as a facsimile printer, the optical image exposure is exposure for printing received data. FIG. 2 is a block diagram showing an example of this case.

The controller 11 controls the image reading section 10 and the printer 19. The entire controller 11 is controlled by a CPU 17. The read data from the image reading unit 10 is
The signal is transmitted to the other station through the transmission circuit 13. Data received from the partner station is sent to the printer 19 through the receiving circuit 12. Predetermined image data is stored in the image memory 16.

A printer controller 18 controls a printer 19. 14 is a telephone.

times! Image information received from 15 (image information from a remote terminal connected via a line) is demodulated by receiving circuit 12, decoded by CPU 17, and sequentially stored in image memory 16. When at least one page of image information is stored in the memory 16, the image information for that page is recorded. The CPU 17 reads one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18.

When the printer controller 18 receives one page of image information from the CPU 17, it controls the printer 19 to record the image information of that page.

Note that the CPU 17 is receiving the next page while the printer 19 is recording.

Images are received and recorded in the manner described above.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

〔Example〕

The present invention will be explained in more detail below with reference to specific examples. The middle part of the example shows parts by weight.

Alcohol-soluble copolymerized nylon resin (average molecular weight 2
9000) 10 parts, methoxymethylated 6 nylon resin (average molecular weight 32000) 30 parts methanol 2
A prepared liquid solution dissolved in a mixed solvent of 60 parts of butanol and 40 parts of butanol was dip coated to form an undercoat layer with a thickness of 14 parts.

Next, 10 parts of a styryl compound having the following structural formula and 10 parts of polycarbonate (weight average molecular weight 33.000) were added to 2 parts of dichloromethane.
0 parts of monochlorobenzene and 40 parts of monochlorobenzene, and this solution was applied by dip coating onto the above-mentioned undercoat layer, and heated at 120°
It was dried at C for 60 minutes to form a charge transport layer with a thickness of 16 μm.

Next, 4 parts of the disazo pigment represented by the following structural formula, 2 parts of polyvinyl butyral (butyralization degree 66%, weight average molecular weight 24,000), and 34 parts of cyclohexanone were dispersed in a sand mill for 24 hours, and then tetrahydrofuran (T ) (F) was added to prepare a dispersion liquid for a charge generation layer. This dispersion was spray-coated onto the charge transport layer and heated at 80°C for 15 minutes.
It was dried for a minute to form a charge generation layer with a thickness of 0.15 μm.

Next, as a coating solution for the intermediate layer, 1 part and 5 parts of the above-mentioned exemplary polymer were dissolved in 95 parts of methanol to prepare an intermediate layer coating. This paint was spray coated on the charge generating layer to form an intermediate layer having a thickness of 1 μm.

Next, 60 parts of a curable acrylic monomer represented by the following structural formula %, 30 parts of ultrafine tin oxide particles with an average particle size of 400 before dispersion, 0.1 part of 2-methylthioxanthone as a photoinitiator, and toluene. 3
00 parts were mixed and dispersed in a sand mill for 48 hours. Using this mixture, a film was formed by spray coating on the intermediate layer, and after drying, a protective layer was obtained by irradiating with ultraviolet light for 20 seconds at a light intensity of 8 mW/cm'' using a high-pressure mercury lamp.

The electrophotographic photoreceptor produced in this way was charged and exposed.
The sample was installed in a normal development type copying machine that repeats the development-transfer-cleaning process in a 1.5-second cycle, and the electrophotographic properties were evaluated at room temperature. Furthermore, the image reproduction durability was repeated 10,000 times. As a result, sensitivity and residual potential were stable, and images without unevenness or black spots could be obtained. Furthermore, a stable image could be maintained even after repeated image formation 10,000 times.

1" 2 vomit 2i Examples of polymers [2] and (3) for intermediate layer coatings.

Electrophotographic photoreceptors were prepared in the same manner as in Example 1, except that (5) and (6:l) modified polyamide resins were used, respectively.

When these photoreceptors were evaluated in the same manner as in Example 1, the sensitivity and residual potential were stable, and good images without unevenness or black spots could be obtained.

The results are shown in Table 1.

Comparison (3) - A photoreceptor was prepared in the same manner as in Example 1 except that the intermediate layer and protective layer of Example 1 above were omitted, and the same evaluation was performed. As a result, as shown in Table 1, the initial electrophotographic properties were good, but after 300 sheets of durability, the charge generation layer on the surface was scraped off, and good images could no longer be obtained.

Comparison Test-I A photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the intermediate layer of Example 1 was omitted.

As a result, as shown in Table 1, the initial electrophotographic sensitivity was extremely low.

! Comparison 5-1 A photoreceptor was prepared and evaluated in the same manner as in Example 1, except that the intermediate layer of Example 1 was spray-coated with a 1.0 μm film of polycarbonate (weight average molecular weight: 35,000). As a result, as shown in Table 1, the initial residual potential was very high, and capri was generated in the background of the image.

Implementation ①--A subbing layer was provided on an aluminum cylinder in the same manner as in Example 1. Next, 10 parts of a charge transport material with the following structural formula and polycarbonate (weight average molecular weight 22,000)
10 parts, 20 parts of dichloromethane, 4 parts of monochlorobenzene
This solution was applied onto the undercoat layer by dip coating and dried at 120°C for 60 minutes to give a film thickness of 5 μm.
A charge transport layer was formed. Next, 4 parts of a disazo pigment with the following structural formula, 2 parts of polyvinylbenzal (benzalization rate 78%, weight average molecular weight 11000), and 3 parts of cyclohexane.
0 part was dispersed for 20 hours using a sand mill, and 60 parts of 2-methyl ethyl ketone was added to prepare a dispersion for a charge generation layer. This dispersion was spray-coated onto the charge transport layer at 80°C.
It was dried at 115° C. to form a 0.10 μm charge generation layer.

An intermediate layer and a protective layer were formed on this charge generation layer in the same manner as in Example 5 to obtain a photoreceptor.

The electrophotographic photoreceptor produced in this way was installed in a reversal development type laser printer that repeats the process of charging, laser exposure, development, transfer, and cleaning in a 1.5 second cycle, and the electrophotographic properties were evaluated. 1000
Durable image formation was performed 0 times. As a result, sensitivity and residual potential were stable, and images without unevenness or black spots could be obtained.

EXAMPLE 1 - An electrophotographic photoreceptor was prepared in the same manner as in Example 6, except that Exemplary Polymer (10) and (2U modified polyamide resin) were used as the coating for the intermediate layer.

When these photoreceptors were evaluated in the same manner as in Example 6, the sensitivity and residual potential were stable, and the images were good with no defects. The results are shown in Table 1.

Soil Base - Soil A photoreceptor was prepared and evaluated in the same manner as in Example 6 except that the intermediate layer of Example 6 was omitted.

As a result, as shown in Table 1, the initial electrophotographic sensitivity was extremely low.

Table 1 [Effects of the Invention] According to the present invention, sensitivity is stable in repeated electrophotographic processes, there is no accumulation of residual potential, and high quality images are maintained without black dot-like image defects (black spots) or fog. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a general transfer type electrophotographic apparatus. FIG. 2 is a block diagram of a facsimile machine using an electrophotographic device as a printer. 1: Photoreceptor, 2: Charging means, 3: Exposure section, 4: Developing means, 5: Transfer means, 6: Cleaning means, 7: Pre-exposure means, 8: Image fixing means. Agent Patent Attorney Seki Yamashita

Claims (4)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer, an intermediate layer, and a protective layer in this order on a conductive support, the intermediate layer contains a polyamide resin having a unit component represented by the following general formula (I). An electrophotographic photoreceptor characterized by the general formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, R_1 is a substituted or unsubstituted alkyl group, R_
2 represents a substituted or unsubstituted alkylene group, and n represents an integer of 1 or more). (2) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a charge transport layer and a charge generation layer in this order. (3) An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1 or 2. (4) comprising the electrophotographic photoreceptor according to claim 1 or 2;
and a facsimile having a receiving means for receiving image information from a remote terminal.