JPS60225851A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To adapt an electrophotographic sensitive body to a printer using a laser as a light source and to enhance sensitivity by incorporating a phthalocyanine pigment in an electrostatic charge generating layer and using an acrylic resin as a binder for a charge transfer layer. CONSTITUTION:The phthalocyanine pigment is incorporated in the charge generating layer of a photosensitive layer of a functionally separated laminate structure, and the charge transfer layer contains as a binder one or more kinds of acrylic resins represented by the formula in which R1 is H or methyl; R2 is a 1-4C satd. alkyl, aromatic, or naphthenic group, and H of these group may be substd. by Cl or F; and n is a value capable of forming a solid polymer. The incorporation of the phthalocyanine pigment sensitive to semiconductor laser beams and the use of the acrylic resin for the binder of the charge transfer layer to be formed on the charge generating layer change configuration of molecules in the interlayer between both layers and the level of a barrier, affect sensitivity and photomemory, and permit a photosensitive body superior in sensitivity and small in PM to be obtained, charging to be specified, and an image good in quality to be formed. As a result, the obtained photosensitive body has high sensitivity and can be used for electrophotography using semiconductor laser beams as the light source.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor suitable for an electrophotographic printer using a semiconductor laser as a light source.

An electrophotographic printer that uses a laser as a light source modulates the laser using an electrical signal that corresponds to image information, and scans the modulated laser onto a photoreceptor using a galvanometer mirror to form an electrostatic latent image. After formation, a desired reproduced image can be formed by sequentially performing toner development and transfer. The laser used at this time was generally helium-cadmium (oscillation wavelength:
441, 6 nm or helium-neon (oscillation wavelength: 6
32.8 nm) gas laser. Therefore, the photosensitive layer used for such a light source is 650
For example, a charge transfer complex of polyvinylcarpasolte trinitrofluorenone may be used as the photosensitive layer, or a tellurium vapor-deposited layer sensitized with selenium may be used as the photoreceptor. A photosensitive layer consisting of a selenium vapor-deposited layer formed on a conductive layer as a charge transport layer and a selenium-tellurium vapor-deposited layer formed on this selenium vapor-deposited layer, and a photosensitive layer that is spectral sensitized with a sensitizing dye. There are also known photosensitive layers that use cadmium sulfide in the photosensitive layer, and photosensitive layers that are functionally separated into a charge generation layer and a charge transport layer that contain organic pigments and are sensitized to the longer wavelength range. It is being

Incidentally, in recent years, semiconductor lasers have been developed that are small, low-cost, and capable of direct modulation. However, this semiconductor laser has an oscillation wavelength of 75
0 nm or more, and the photoreceptor described above has no or almost no sensitivity in the wavelength region of 750 nm or more, making it difficult to use semiconductor lasers in electrophotographic printers. I'm letting it happen.

On the other hand, 1. Recently, it has become known that phthalocyanine pigments are effective as materials sensitive to semiconductor lasers, but they are used as charge generation layers in functionally separated multilayer electrophotographic photoreceptors. It was found that the sensitivity and photomemory of the photoreceptor vary greatly depending on the type of binder in the charge transport layer.

An object of the present invention is to provide an electrophotographic photoreceptor having the best characteristics by combining an optimal binder for a charge transport layer when using a phthalocyanine pigment.

Another object of the present invention is to provide an electrophotographic photoreceptor suitable for an electrophotographic printer using a laser as a light source.

Another object of the present invention is to provide an electrophotographic photoreceptor suitable for an electrophotographic printer using a semiconductor laser having an oscillation wavelength of 750 nm or more as a light source.

Another object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity in a wavelength range of 750 nm or more.

Another object of the present invention is to provide an electrophotographic photoreceptor with improved photomemory properties.

This object of the present invention is achieved by an electrophotographic photoreceptor provided with a photosensitive layer having a laminated structure consisting of a specific charge generation layer and a specific charge transport layer.

The electrophotographic photoreceptor of the present invention is characterized by containing a phthalocyanine pigment as a charge generation layer and one or more acrylic resins represented by the following formula as a binder for the charge transport layer. Body-R2 R'H or CH.

1' R2: represents a saturated alkyl group having 1 to 4 carbon atoms, an aromatic ring group, or a 7-tenyl group, and these hydrogen atoms are chlorine,
It may be replaced with a fluorine atom.

n: An arbitrary integer that allows the polymer to become solid.

It is not clear how the binder in the charge transport layer affects the electrophotographic properties of the photoreceptor, but when the charge transport layer is laminated on the charge generation layer, charge transport material molecules at the interface between the two layers It is thought that the alignment, barrier level, and degree change depending on the binder, which affects sensitivity and photomemory properties.

The phthalocyanine pigment used in the present invention is represented by the following structural formula.

In the formula, M is a metal atom, X is an anionic atom, and n is a valence of 2 or more.

As the binder, for example, polyvinyl acetal, polyvinyl acetal, polyester, polycarzenate, polyamide, polyurethane, phenol resin, etc. can be used. The proportion of the resin forming the binder in the charge generation layer is preferably 80% or less, preferably 50% or less, and particularly preferably 40% or less.

In dispersing the above-mentioned OS material, a known method using a sol mill, ato 2 iter, etc. can be employed, and in this case, it is desirable that the pigment particles have a size of 5 microns or less, particularly 0.5 microns or less. The dispersion liquid containing the pigment dispersed in this manner is applied by a coating method such as a Fleid coating method, a Mayer coating method, a spray coating method, an immersion coating method, a curtain coating method, or a bead coating method. The thickness of the charge generation layer is suitably 5 microns or less, preferably 0.05 to 1 micron.

The spectral absorption of the charge generation layer formed in this way is, for example, in the case of aluminum chloride phthalocyanine, it has strong absorption in the region of 750 to 850 nm as shown in the drawing, and it is difficult to use for lasers in the wavelength region of 750 nm or more. Charges generated by exposure can be injected into the stain charge transport layer using an electric field. As the charge transport material, polycyclic aromatic compounds such as anthracene, bire/, 7-enanthrene, coronene, etc. are used in the main chain or side chain, or indole, carbazole, oxazole, isoxazole, thiazole,
Compounds having nitrogen-containing cyclic compounds such as imidazole, pyrazole, oxadiazole, birapurin, thiadiazole, and triazole, human 2-sine compounds, and the like are used. In the present invention, an acrylic resin represented by the following formula is used as a binder for these charge transport materials.

An electrophotographic photoreceptor nose-R2 R4:H or CH characterized by containing gold in one or more acrylic resins represented by the following formula.

R2: represents a saturated alkyl group having 1 to 4 carbon atoms, an aromatic ring group, or a naphthene group 1; these hydrogen atoms may be replaced with chlorine or fluorine atoms.

n: An arbitrary integer that allows the polymer to become solid.

Examples of such binders include polymethyl acrylate, polymethyl methacrylate, polyethyl methacrylate,
Examples include single or copolymers of two or more of polyn-butyl methacrylate to polytrifloethyl methacrylate, polycyclohexyl methacrylate, and polybenzyl methacrylate. In addition, in the case of copolymers of these acrylic resins and other resins, the resins to be combined are:
Examples include polystyrene, polyacrylonitrile, vinyl acetate, etc. Furthermore, in the case of a polymer blend, cellulose, vinyl chloride-vinyl acetate copolymer, epoxy resin, etc. are appropriately mixed. In such a case, the acrylic resin is contained in an amount of 20 or more, preferably 4 (1 or more) of the entire binder resin.

The blending ratio of the charge transport material and these binders is preferably 10 to 500 parts by weight of the charge transport compound per 100 parts by weight of the binder. The thickness of this charge transport layer is 2
~100' microns, preferably 5-30 microns. In addition, as the coating method used when providing the charge transport layer, conventional methods such as blade coating method, Mayer-Percoch ink method, spray coating method, dip coating method, bead coating method, air knife coating method, and curtain coating method are used. Can be used.

Further, an undercoat layer may be provided between the charge generation layer and the conductive layer. This subbing layer prevents the injection of free charges from the conductive support to the photosensitive layer when the photosensitive layer having a laminated structure is charged, and also allows the photosensitive layer to be integrally adhered to the conductive support. It acts as an adhesive layer. This intermediate layer includes polyethylene, I-lysylpyrene, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenolic resin, epoxy resin,
polynisder resin, alkyd resin, polycarbonate,
Polyurethane, polyimide resin, vinylidene chloride resin,
Vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, water-soluble Polyny 7-L/N, nitrocellulose,
It can be made using casein, gelatin, etc. The thickness of this intermediate layer or adhesive layer is suitably 0.1 to 5 microns, preferably 0.5 to 3 microns.

In addition, in the electrophotographic photoreceptor of the present invention, in order to uniformly inject carriers into the charge generation layer and the upper charge transport layer, the surface of the charge generation layer may be polished to a mirror finish, if necessary. can. As the mirror finishing method, for example, the method disclosed in Japanese Unexamined Patent Publication No. 55-155356 can be used.

The support used in the electrophotographic photoreceptor of the present invention may be any support as long as it is endowed with conductivity, and any type of conductive layer conventionally used may be used. Specifically, metals such as aluminum, copper, stainless steel, and brass, and TFC deposited with aluminum, gold, cuprous iodide, etc., are laminated glass or conductive particles, such as carden black, silver particles, aluminum particles, Examples include a substrate provided with a layer in which tin oxide particles, zinc oxide particles, etc. are dispersed in a binder resin, or a glass material in which the above particles are dispersed. Furthermore, the shape of the book may be a sheet, a cylinder, or any other book shape.

The electrophotographic photoreceptor of the present invention has a coherent property (
It can be applied to devices that utilize a four-stage system using coherent (coherent) light as a light source, such as an electrophotographic printer or an electrophotographic plate-making system.

According to the present invention, compared to conventional laser electrophotographic photoreceptors, it has significantly higher sensitivity in the wavelength range of 750 nm or more;
You can also improve your photo memory.

The electrophotographic photoreceptor of the present invention is particularly suitable for an electrophotographic printer using a semiconductor laser as a light source.
It can also be used with a photoreceptor for ordinary electrophotography using an incoherent light source.

The present invention will now be described according to examples.

Example 1 A solution of casein in ammonia (11.2 g of casein, 1 part of 216 ammonia water) was placed on a mirror-finished aluminum cylinder.
g, water 222+114') by dip coating method and dried to give a coating weight of 1. A subbing layer of Ofl/m2 was formed.

Next, 1 part by weight of aluminum chloride phthalocyanine, 1 part by weight of butyral resin (S-LEC BM-2, manufactured by I-Sui Kagaku Co., Ltd.) and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a Ga-lumil disperser. This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generating layer. The film thickness at this time is 0.3μ
Met.

Next, 1 part by weight of the following compound (1) as a charge transport material, 1 part by weight of the following compound (2) as a binder, and 0-CH.

n=1X10 to 3X10' 6 parts by weight of monochlorobenzene was mixed and dissolved by stirring with a stirrer. This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The film thickness at this time was 12μ.

Examples 2 to 6 Electrophotographic photoreceptors were produced in the same manner as in Example 1, except that the charge generating material, the charge transporting material, and their binders were combined as shown in Table 1.

Table 1 0-CR2 n=3X10' (Acrylic content 60%) n=4X10 (Contains 80% ethyl methacrylate) Blend of 70% cellulose acetate butyrate (trade name CAB-381) Charge Transport Material The photoreceptor thus prepared was subjected to a -5 kV corona discharge. The surface potential at this time was measured (initial potential Vo)
. Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay Vs).

Sensitivity was evaluated by measuring the amount of exposure (E strong microphone pgy-xytJ) required to attenuate the potential V after dark decay. At this time, gallium was used as the light source.
Aluminum arsenic, semiconductor laser (oscillation wavelength 790
nm) was used. In addition, photomemory property (PM)
The photoreceptor was left under 600 lux for 3 minutes, then left in a dark place for 1 minute, and the charge was measured again under the same conditions.
PM). In other words, PM is expressed by the following equation.

PM=potential before strong illuminance exposure−potential charging characteristics after strong illuminance exposure are shown in Table 2.

Table 2 Comparative Examples 1 to 4 Photoreceptors were prepared in the same manner as in Example 1 except that the charge generating material and charge transporting material binder shown in Table 3 were used.

Cap 4 As described above, when a phthalocyanine pigment is used as a charge generating material, the electrophotographic photoreceptor of the present invention containing a polymethacrylic acid ester as a binder in the charge transport layer has extremely high sensitivity compared to the photoreceptor of the comparative example. It was a photoreceptor with excellent properties and low PM content.

If the PM is small, even if the user removes the photoreceptor from the LBP or copying machine and exposes it to illumination light or natural light, the charging characteristics will be stable, and a stable and high-quality image can be obtained. There are countless practical advantages, such as:

[Brief explanation of drawings]

The drawing is an explanatory diagram showing an absorption spectrum when a resin dispersion of aluminum chloride phthalocyanine is formed into a film on a glass plate.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor provided with a photosensitive layer having a laminated structure consisting of a charge generation layer and a charge transport layer, wherein the charge generation layer contains a phthalocyanine pigment, and a binder for the charge transport layer. An electrophotographic photoreceptor characterized by containing 1s or 2 or more types of acrylic resins represented by the following formula - R2 R1: H or CH3 R2: a saturated alkyl group having 1 to 4 carbon atoms, or an aromatic ring or naphthesi group, and these hydrogen atoms are chlorine,
It may be replaced with a fluorine atom. n: An arbitrary integer that allows the polymer to become solid. The electrophotographic photoreceptor described above.