JPS6250767A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having an improved sensitivity in a long wavelength range of from an infra-red ray to a near infra-red ray and an improved stability by incorporating a specific cyanine dyestuff as a sensitizing dyestuff for a white pigment type photoconductive body, to the titled body. CONSTITUTION:The cyanine dyestuff shown by the formula is incorporated to the white pigment type optical conductive body such as a zinc oxide and a titanium dioxide etc. In the formula, R1 and R2 are each 7-20C a straight chain alkyl group, X<-> is I<->, Br<->, Cl<->, O3<->S-C6H4-CH3, and ClO4<->, Z and Z' are each a nitro, a cyano or an alkylsulfonyl group, Y is a S atom or -C(R2)R3 group, Y' is a S atom or a -C(R2')R3' group, R2, R2', R3, R3' are each an alkyl group. The titled body is prepared by forming the photoconductive layer contg. the prescribed composition and a resin. Accordingly, as the titled body comprises the prescribed cyanine dyestuff, the titled body may be sensitized spectrally in the long wavelength range of form the infrared to the near infra red rays and is suitable to use for a semiconductor laser printer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoconductor, and more particularly to improvement of spectral sensitization of a white pigment-based photoconductor.

(Summary of the Invention) The present invention provides a sensitizing dye for a white pigment-based photoconductor using the general formula (wherein R+ and R* are linear alkyl groups having 7 to 20 carbon atoms,
Any one of these, z and z' are each a nitro group.

Represents either a cyano group or an alkylsulfonyl group,
However, R*+R'tJs+R'* each represents an alkyl group. ) The present invention aims to provide an electrophotographic photoreceptor that is spectrally sensitized to long-wavelength infrared to near-infrared light using a cyanine dye shown in .

[Conventional technology]

White pigment-based photoconductors such as zinc oxide, titanium dioxide, zinc sulfide, etc. exhibit excellent photoconductive properties and are widely used in electrophotographic photoreceptors.

In this case, since the sensitive wavelength range of the white pigment-based photoconductor alone is in the ultraviolet region, a sensitizing dye is usually added to perform spectral sensitization to widen the sensitive wavelength range.

For example, recording equipment that forms electrostatic latent images using laser light, such as laser printers, requires an electrophotographic photoreceptor that is highly sensitive to the laser light. Electrophotographic photoreceptors have been developed that are spectrally sensitized to the long wavelength visible light range, which is the wavelength range of argon laser light or helium-neon laser light, by adding acidic sensitizing dyes such as green, crystal bioleft, or erythrosine.

[Problems to be solved by the invention]-1 However,
There are almost no known sensitizing dyes capable of spectral sensitization to the infrared or near-infrared region for application to semiconductor lasers (wavelengths of about 600 to 1000 n11), which are smaller and cheaper than these lasers.

There is an example of an electrophotographic photoreceptor that is spectrally sensitized to a wavelength range of 700 to 9Q Orv, which corresponds to semiconductor laser light, by adding a small amount of cyanine dye to zinc oxide. When trying to spectral sensitize to long wavelength range,
It is necessary to use a methine chain with a long methine chain, and there is a problem that the stability of the dye is generally poor. In addition, white pigment-based photoconductors such as zinc oxide have the disadvantage that they themselves act as photocatalysts (therefore, they tend to decompose sensitizing dyes when exposed to light).

The stability of sensitizing dyes is particularly important when using high-intensity light such as laser light as the writing light source, and poor stability of sensitizing dyes is a major drawback for electrophotographic photoreceptors. .

Therefore, the present invention was proposed in view of the conventional situation, and has high sensitivity in the long wavelength range of infrared to near-infrared, and is very suitable for use in semiconductor laser printers, etc.
It is an object of the present invention to provide an electrophotographic photoreceptor having excellent stability.

[Means for solving problems]

As a result of long-term intensive research to achieve the above-mentioned purpose, the present inventors have discovered that certain cyanine dyes have excellent sensitizing properties to long wavelengths in the infrared to near-infrared light region, and are stable. The present invention was completed by discovering that the present invention has high properties, in which a white pigment-based photoconductor is coated on a conductive support with the general formula 8% (in the formula, R+ and Rz have a carbon number of 7 to 20 straight chain alkyl groups,
Any one of these, z and z' are each a nitro group.

Represents either a cyano group or an alkylsulfonyl group,
However, Rt* R'z+ Rff+ R'l each represents an alkyl group) It is characterized by providing a photoconductive layer containing a dye and a resin.

Here, as the white pigment-based photoconductor, zinc oxide, titanium dioxide, zinc sulfide, etc. are used, while the resins are acrylic resin, silicone resin, polyester resin, vinyl acetate resin, styrene resin.

Highly insulating resins such as alkyd resins and polyurethane resins are used.

The above-mentioned amount of added dye is 0.0000000000000 for a white pigment-based photoconductor.
It is preferable that the amount is in the range of 0.01 to 0.50% by weight. If the amount added is too small, the sensitivity will not be sufficient, and if it is too large, the charging characteristics will deteriorate. The amount of resin used is 5 to 100% by weight based on the white pigment photoconductor.
Preferably it is 15 to 50% by weight.

In addition to the above-mentioned dye, white pigment photoconductor, and resin, an electron-philic compound serving as a sensitizing agent and other additives may be added to the photoconductive layer.

Examples of the electron-affinity compound include benzoquinone, chloranil, phthalic anhydride, dinitrobenzoic acid, and tetracyanoquinodimethane. The amount used is preferably 0.5% by weight or less, based on the white pigment photoconductor; if the amount used exceeds 0.5%, dark decay may increase.

To produce the electrophotographic photoreceptor of the present invention, a white pigment-based photoconductor, the above-mentioned dye and resin (additives such as an electron-affinity compound as necessary) are placed on a conductive support in a solvent such as toluene. A photoconductive layer forming liquid dissolved or dispersed in an organic solvent may be applied and dried.

As the conductive support, a metal plate such as an AN plate or a Cu plate, or a plastic film or the like on which a conductive substance such as a metal or a metal oxide is deposited is used.

Furthermore, the white pigment-based photoconductor may have the above-mentioned dye adsorbed thereon. In this case, the white-pigment-based photoconductor is added and dispersed in a solution in which the above-mentioned dye is dissolved, and then the solvent is removed. A photoconductive layer forming liquid may be prepared by adding a resin (or its solution) with or without evaporation.

[Function] The cyanine dye that spectrally sensitizes a white pigment-based photoconductor tries to obtain a sensitizing effect by adsorbing it well to the photoconductor particles.
．． R'+ is a short alkyl group such as CJs or CHgC
It is common to use a group such as 0OH,C)lx-CHCHt to improve interaction. However, since the interaction is good, the white pigment-based photoconductor such as zinc oxide is likely to act as a photosensitizer, which may deteriorate the stability of the dye. An alkyl group having 7 or more carbon atoms is introduced to control the interaction by ensuring adsorption with the white pigment photoconductor while providing compatibility with the resin that serves as the binder. and,
This prevents decomposition of the dye due to photocatalytic reaction. Furthermore, in order to increase the sensitization wavelength to a long wavelength range without making the methine chain unnecessarily long, we introduced a strong electron-withdrawing group such as a nitro group into the cyanine ring to improve the sensitization effect. There is.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

Example: To 100 g of zinc oxide, 0.5 g of phthalic anhydride as an electron-affinity compound and 0.3 g of a dye represented by the formula as a sensitizing dye.
g, and then add 200 g of acetone-ethanol mixed solvent.
After adding g, ultrasonic dispersion was performed for 10 minutes.

After dispersion, vacuum drying was performed, 30 g of acrylic resin and 250 g of toluene were added thereto, and the mixture was dispersed in a ball mill for about 1 hour to prepare a photoconductive layer forming liquid.

This photoconductive layer forming liquid was coated on an A1 vapor-deposited polyethylene terephthalate film at a coating JI of 100 to 200 μm to prepare an electrophotographic photoreceptor.

This electrophotographic photoreceptor is charged, and the wavelength is 780n++.
When exposure was performed using a semiconductor laser with an output of 3 mW and the sensitivity was examined, the energy required to reduce it by half was less than 5 μJ/d.

Furthermore, when we repeated the durability test of charging (negatively) and irradiating the conductor with laser light, there was no change even after several hundred repetitions.

Furthermore, this electrophotographic photoreceptor was heated under a fluorescent lamp (approximately 5001 ux).
), no fading was observed, indicating high stability against light.

Comparative example
Ru.

An electrophotographic photoreceptor was prepared in the same manner as in the example except that the dye represented by the formula was used as the sensitizing dye.

The obtained electrophotographic photoreceptor was exposed to a fluorescent lamp (approximately 500 lux
), fading of color was observed within a few hours.

〔Effect of the invention〕

As is clear from the above description, the electrophotographic photoreceptor of the present invention is spectrally sensitized in a long wavelength region such as the infrared or near-infrared region, and therefore is very suitable as an electrophotographic photoreceptor for semiconductor laser printers. It is suitable for

Claims (1)

[Claims] On a conductive support, there is a white pigment-based photoconductor and a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (in the formula, R_1 and R_2 are linear alkyl groups having 7 to 20 carbon atoms , X^- is I^-, Br^-, Cl^-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ClO_4^-, Z and Z' are nitro group, cyano group, alkylsulfonyl, respectively Any one of the groups, Y is S or ▲ there is a mathematical formula, chemical formula, table, etc. ▼, Y' is S or ▲ mathematical formula, chemical formula,
There are tables etc. Represents ▼. However, R_2, R'_2, R
_3 and R'_3 each represent an alkyl group. ) An electrophotographic photoreceptor comprising a photoconductive layer containing a dye represented by the following formula and a resin.