JPS60189750A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve carrier generation efficiency and to enhance sensitivity by adding, as the material of an electrostatic charge generating layer, a specified amt. of the same material as a conductive substrate to a functionally separated laminate type photosensitive layer. CONSTITUTION:An ultrafine powder of aluminum same as the material of a conductive substrate of an aluminum plate is added to a charge generating layer (CGL) of a laminated photosensitive layer of said CGL and a charge transfer layer CTL formed on said conductive substrate in an amt. of 5-40wt% of a charge generating material (CGM). Said aluminum powder same as the material of the conductive substrate is dispersed concentratedly in the width of at largest 1/2 the total width of CGL from the interface of the substrate till the middle of CGL. It is preferred to form CGL by vapor depositing CGM together with the ultrafine aluminum powder. The addition of aluminum same as the substrate material into CGL enlarges the substantial area of the interface between CGL and the substrate, and the site contributing to charge generation, thus permitting both of charge generating efficiency and sensitivity of the photosensitive body to be elevated.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor.

This invention relates to a laminated electrophotographic photoreceptor using the Carlson method.

[Technical background of the invention]

In recent years, semiconductor lasers have come to be used as light sources for printers using electrophotography, but since the oscillation wavelength of semiconductor lasers is long at approximately 800 nm, electrophotography that can maintain high sensitivity even in this long wavelength range In the early days of photoconductor development, when photoconductors were being actively developed, photoconductors with a single layer of photoconductor laminated on a conductive support were used. A photoreceptor having a structure in which a generation layer and a charge transport layer are separated is used.

In the latter photoreceptor, since the charge generation layer is thinner than the charge transport layer and has weaker mechanical strength, the charge transport layer is usually the uppermost layer and the charge generation layer is the middle layer.

As the material for the charge transport layer of the photoreceptor, since there is no need to generate a charge in the layer, a charge transport material having a submerged charge retention ability and charge transport ability is used, and as a result, the above-mentioned latter The former photoreceptor has better sensitivity, chargeability, etc. than the former photoreceptor.

The charge transport material is transparent to visible light, and examples of such materials include polymeric organic semiconductors such as polyvinyl rubazol or its derivatives; low molecular weight organic semiconductors such as oxadiazole derivatives, triphenylamine derivatives, or pyrazoline conductors. Those dispersed in organic binders such as polyester resins are known. These charge transport materials are capable of transporting holes, but not electrons. As the charge generating substance, dyes such as copper phthalocyanine are usually used, and as the conductive support, AI! A plate or a polyethylene terephthalate resin film on which a metal such as A/ is deposited is used.

The electrostatic latent image forming mechanism of the photoreceptor described above is considered as follows. In other words, excitons generated in the charge generation layer by light irradiation dissociate into electrons and holes within the charge generation layer or at the boundary between the charge generation layer and the charge transport layer, generating carriers (holes). The carriers are then injected into the charge transport layer.

An electrostatic latent image is formed by neutralizing negative charges on the surface of the photoreceptor. On the other hand, electrons migrate to the conductive support.

[Problems with background technology]

In order to improve the sensitivity of such a laminated photoreceptor, the number of carriers generated within the charge generation layer must be increased.

It is necessary to inject the generated carriers into the charge transport layer without recombining or trapping them.

As a result of various studies aimed at improving charge generation, AI! The present invention was based on the discovery that charge generation is mainly caused by a Schottky barrier generated at the interface between a conductive substrate and a charge generation layer.

[Purpose of the invention]

An object of the present invention is to provide a highly sensitive electrophotographic photoreceptor with good carrier generation efficiency.

[Summary of the invention]

The present invention provides an electrophotographic/photosensitive member having a laminated structure of a charge generation layer and a charge transport layer on a conductive support.
It is characterized by adding 40 wt%. In other words, by adding a conductive support material to the charge generation layer, the effective area of the interface between the charge generation material and the conductive support increases, increasing the number of sites that are harmful to charge generation, resulting in high sensitivity. Conceivable.

The present invention will be explained in more detail below.

In the photoreceptor of the present invention, a C2 conductive material is added in the charge generation layer for the purpose of increasing the contact area between the charge generation material and the conductive material, but other than that, the photoconductor is separated into a generation layer and a transport layer. The same photoreceptor as a conventional photoreceptor is used.

The present invention≦The conductive materials that can be used as two agents are A/ and In.

Metals such as Au, Cu, Ni, Sn, Zn, and Ag are used. As the support, these metal cylinders may be used, or a conductive substance may be deposited on a resin film.

It is preferable that the charge generation material constituting the charge generation layer has a higher ionization energy and a higher Fermi level than the charge transport material in the charge transport layer. The layer usually has a thickness of 0.1 to 1 μm.

The charge generating material is an organic semiconductor material that has the function of supplying holes to the charge transport layer to neutralize the negative charges of the layer, and has an absorption band in a long wavelength range (400 to 900 nm). As the substance, any substance b that has been conventionally used as a charge generating substance in electrophotographic photoreceptors can be used, but aromatic dyes are usually used.

An example of this is binding or, for example, % copper phthalocyanine.

Phthalocyanines such as aluminum phthalocyanine and germanium phthalocyanine, pyrylium salt dyes, azo dyes, perylene dyes, indigoid dyes, perinone dyes, quinone dyes, anthraquinone dyes, quinacridone dyes, dioxazine dyes, and cyanine dyes. can give.

The amount of conductive material added to these materials is 5 to 40w.
If t* is appropriate and less than that, the effect of addition is not obvious. On the other hand, if it is too large, the conductivity of the charge generation layer will increase,
The saturation charging potential becomes low and the sensitivity is adversely affected, and the conductive material dispersed in the charge generation layer is mainly distributed from the interface of the conductive support to at most 1/2 of the thickness of the entire charge generation layer.
It is preferable to concentrate up to . In other words, the conductive material is largely dispersed near the interface with the support, is hardly present near the transport layer, and is dispersed in the thickness direction 12 within charge generation 1#.
Most preferably, the number of degrees gradually decreases by ≦2.

Methods for forming such a charge generation layer include coating a solution in which a charge generation material and a conductive material are dispersed in a polymer as a binder, and co-evaporation to form a charge generation material and a conductive material. There is a method of simultaneous vapor deposition. In the case of the coating method, a dispersed solution is coated and the conductive material gradually settles during the drying process, so that the concentration near the conductive support becomes high. Although this method makes it difficult to control the distribution of conductive material in the thickness direction, it is suitable for mass production and is suitable for materials that cannot be vapor deposited. As a binder.

The type of the island molecule compound is not limited to any known binder materials for electrophotographic photoreceptors, such as polystyrene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, and polyvinyl acetal.

Phenol resins, epoxy resins, and alkyd resins can be used as appropriate. Further, the conductive material preferably has an ultrafine powder average particle diameter of 0.3 μm or less, and if it is larger than that, there is a problem in film formability.

Co-evaporation methods include a method in which a conductive material and a charge-generating material are mixed together and a dual method in which they are separately deposited from two crucibles. Two-dimensional vapor deposition, which is performed by setting and vapor depositing, is effective because there are no restrictions on materials and it is easy to control the thickness direction.

The charge transport layer is made of a hole transport material that is transparent to visible light in the long wavelength range. The layer usually has a thickness of 2 to 50 μm. As the material, a material in which a high-molecular organic semiconductor or a low-molecular organic semiconductor is dispersed in an organic binder is usually used.

〔Effect of the invention〕

According to the photoreceptor of the present invention, since the conductive material is added to the charge generation layer, the number of contact surfaces with the charge generation material, that is, charge generation C: effective active sites is increased, so that the charge generation efficiency is increased. A photoreceptor with good sensitivity and high sensitivity can be obtained.

[Embodiments of the invention]

Example 1 A commercially available A/plate (99, 91) was used as a conductive support.

A mixed layer of copper phthalocyanine and A/ was provided thereon as a charge generation layer by co-evaporation. Pel jar internal pressure is 5
A/
Vapor deposition is carried out at 850-900℃ using a spiral boat.
When the shutter is opened, vapor deposition starts at the same time, and after 2 minutes, the A/
The vapor deposition was completed, and then 10 minutes later I: Copper phthalocyanide.The vapor deposition was completed, and the charge generation layer 0 with mulch dispersed near the support.
．． 3μ was formed. On top of that, as a charge transport layer, PUK
A photoreceptor was prepared by applying a solution of IQwt (chlorobenzene, THF mixed solvent) to a thickness of about 10 μC using a spinner.

Next, a photoreceptor having the same structure as the above-mentioned photoreceptor was prepared by using a charge generation layer in which only copper phthalocyanine was deposited at 0.3 μm, and used as a comparative example.

The charging and attenuation behavior of these photoreceptors was investigated using an electrostatic paper analyzer. The result is the exposure amount required to attenuate the initial value vO of the surface charge to 1/2 (unit: I!ux - sec).
Expressed as 8.5/u x s in the example with negative charge
ec (Vq=-980V) vs. l81ux sec (Vo =-1020V) in the comparative example
Met.

Chemical analysis of the added A/ in the charge generation layer of the example showed that it was 3 Owt%, and it was found that a large amount of A was present at about 800λ from the support in the thickness direction.
Confirmed by humans.

Example 2 On the same λl support as in Example 1, a mixed layer of polychlorosteel phthalocyanine A/ was provided by codeposition.

Polyfluoro steel phthalocyanine is 550″0-57 in a quartz crucible at Pelger internal pressure s x tO-6 tart.
At 0"O, A/deposition was carried out using a spiral boat at 850
The shutter was opened at ~900"0 and vapor deposition was started at the same time. After 3 minutes, the AI! vapor deposition was finished, and after 7 minutes, the vapor deposition of polychlorosteel phthalocyanine was finished. The charge generation layer thus obtained had a thickness of 0.2μ, The amount of M added was 18wt%, which was widely dispersed up to 600% in the thickness direction.On top of that, oxic diazole 60w expressed by the following formula was added as a charge transport layer.
t% is polyester resin [bidispersed solution is 15 μm
A photoreceptor was prepared by coating the film to a thickness of C2.

As a comparative example, a photoreceptor having the same structure as the above-mentioned photoreceptor was prepared except that only polychlorosteel phthalocyanino was deposited and nine layers were used as a charge generation layer.

When these photoreceptor characteristics were evaluated, the initial charge amount of Example was 7.61 at -5oo V! ux sec, whereas in the comparative example, the initial charge amount was 21.5/u at -840V.
It was x sec.

Representative Patent Attorney Kensuke Norichika (and 1 other person) Continued from page 1 ■ Int, C1, ' fi Separate symbol Inside the office ■ Inventor Ko Mizushima - Kawadokoro Reference number 2H 5F 1 Komukai Toshiba-cho, Saiwai-ku, Saki-shi Tokyo Shibaura Electric Co., Ltd. General Research Center

Claims (1)

[Scope of Claims] 1) In an electrophotographic photoreceptor in which a photosensitive layer having a laminated structure of a two charge generation layer and a charge transport layer is provided on a conductive support,
An electrophotographic photoreceptor characterized in that the same material as the conductive support is added to the charge generation layer material in an amount of 5 to 40 wt% based on the charge generation material. 2) The additive component made of the same material as the conductive support in the charge generation layer is mainly concentrated from the interface of the conductive support to at most 1/2 of the thickness of the entire charge generation layer. An electrophotographic photoreceptor according to claim 1, characterized in that the electrophotographic photoreceptor is dispersed in: 3) The quadruplets photographic photoreceptor 0 according to claim 1, wherein the charge generation layer made of a charge generation material and a conductive material is formed by co-evaporation.