JPS6318742B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor using a phthalocyanine compound as a charge generating material. Conventionally, inorganic compounds such as selenium and cadmium sulfide have been mainly used as photoreceptors for electrophotography, but many of these materials are designated as poisonous, deleterious substances, or specified chemical substances, and their handling, It has the disadvantage of requiring special care when disposing of it. On the other hand, in contrast to photoreceptors using these inorganic substances, electrophotographic photoreceptors using organic photoconductors have recently been proposed as non-toxic and inexpensive photoreceptors. Typical examples include a large number of organic compounds, such as sensitized poly-N-vinylcarbazole, polyvinylanthracene, polyacenaphthylene, and various phthalocyanine compounds. Among these, phthalocyanine compounds are superior in terms of cost and sensitivity. However, with electrophotographic copying machines equipped with electrophotographic photoreceptors using phthalocyanine compounds,
When copying a document containing red parts such as red stamps, red letters, and red lines in black and white, the image density of the part of the resulting image that corresponds to the red part on the original is equivalent to the blue part or black part of the original. There is a major practical problem in that the density of the image is very low compared to the image density of the area. This is because electrophotographic photoreceptors using phthalocyanine compounds have extremely high sensitivity in the red region.
Since the photoreceptor exhibits photoconductivity to the same degree for red reflected light from the red portion of the original and white reflected light from the white portion, an electrophotographic copying machine equipped with the photoreceptor has a This is because the red part of the image is processed as a white part. An object of the present invention is to overcome the above-mentioned drawbacks and provide an electrophotographic photoreceptor using a practically usable phthalocyanine compound. The present invention provides a charge transport layer of a photoreceptor comprising a charge generation layer containing a phthalocyanine compound as a charge generation material, provided on a conductive substrate, and a charge transport layer provided on the upper surface of the charge generation layer. To,
By adding and containing an appropriate amount of a dye that has an absorption maximum in the red region of the spectrum, the image density of the portion corresponding to the red portion of the document becomes extremely high in the image obtained when copying a document containing the red portion. It is based on what was discovered. Examples of the present invention will be described in detail below. Example 1 1 part by weight of α-type copper phthalocyanine (“2712, Cyanine Blue B”: Toyo Ink Co., Ltd. trade name) and polyester resin (“Vylon 200”: Toyobo Co., Ltd. trade name)
2 parts by weight were mixed with 80 parts by weight of tetrahydrofuran in a ball mill for 150 hours to prepare a uniform coating solution. This coating liquid was applied onto a 10 μm thick aluminum foil laminated to a 75 μm thick polyester film using a film applicator so that the coating thickness after drying was 15 μm.
Dry. On the charge generation layer thus obtained, 3 parts by weight of cyanine (absorption maximum 5800-6100 Å: manufactured by Eastman Kodak), 3-(p-methoxyphenyl)-1,5-diphenyl-2- A solution prepared by dissolving 1,000 parts by weight of pyrazoline and 1,000 parts by weight of polycarbonate (Panlite L-1250: trade name of Teijin Ltd.) in 10,000 parts by weight of tetrahydrofuran was applied so that the dry film thickness was 15 μm.
A charge transport layer was prepared. The sensitivity, that is, the half-decreased exposure (E _1/2 ) of the electrophotographic photoreceptor composed of the charge generation layer and the charge transport layer thus obtained was determined to be 10.1 lux·sec. The half-decreased exposure amount is determined by first charging the photoreceptor in a dark place with a corona discharge of -6 kV, then irradiating it with white light at an illuminance of 5 lux, and measuring the amount of exposure required for the surface potential to attenuate to half of the initial surface potential. I asked for it. For this measurement, an electrostatic recording paper testing device "SP-428 improved model" manufactured by Kawaguchi Electric was used. Next, this electrophotographic photoreceptor was installed in an electrophotographic copying machine and its color sensitivity was examined, and the results shown in Table 1 were obtained.

[Table] As is clear from Table 1, in an electrophotographic photoreceptor comprising a charge generation layer containing a phthalocyanine compound as a charge generation material and a charge transport layer provided on the charge generation layer, the charge transport layer The photoreceptor containing a dye having an absorption maximum in the red region of the spectrum in its charge transport layer is more sensitive to originals containing a red region than the photoreceptor that does not contain a dye having an absorption maximum in the red region of the spectrum in its charge transport layer. When a copy is made, the image density of the portion corresponding to the red portion of the original is very high, and its practical value is great. Example 2 "Brilliant Milling Green B" was applied on the charge generation layer obtained in the same manner as in Example 1.
(CI42100, absorption maximum 6354Å: Hodogaya Chemical Industry Co., Ltd.)
(trade name) 1 part by weight, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline (``ASPP'': Anan Sangyo Co., Ltd. trade name) 300 parts by weight , and polycarbonate (“Panlite L-1250”: Teijin Ltd. product name)
A paint was obtained by mixing 300 parts by weight with 3000 parts by weight of tetrahydrofuran in a ball mill for 170 hours.
This paint was applied to give a dry film thickness of 15 μm to prepare a charge transport layer. The electrophotographic photoreceptor composed of the charge generation layer and the charge transport layer thus obtained was treated in the same manner as in Example 1 using filters of each color (Ratten filter manufactured by Kodatsu), and the half-decreased exposure amount was determined. The light sensitivity was determined. In this case, blue filter No. 47, green filter No. 58, and red filter No. 25 were used. The results are shown in Table 2.

[Table] As is clear from Table 2, in an electrophotographic photoreceptor comprising a charge generation layer containing a phthalocyanine compound as a charge generation material and a charge transport layer provided on the charge generation layer, the charge transport layer A photoreceptor containing a dye having an absorption maximum in the red region of the spectrum has no significant difference in spectral sensitivity characteristics in the visible region, and is an excellent photoreceptor in practical use. In the above examples, an α-type copper phthalocyanine pigment was used as the phthalocyanine compound, but the present invention provides an electrophotographic photoreceptor using other phthalocyanine compounds such as other metal phthalocyanines, halogenated phthalocyanines, and metal-free phthalocyanines as charge-generating materials. Needless to say, it can also be applied to Furthermore, the dye may be any dye that has an absorption maximum in the red region of the spectrum, and is not limited to the dyes used in the Examples. In this way, when the photoreceptor of the present invention copies a document containing a red portion in black and white, the image density of the portion corresponding to the red portion of the resulting image is lower than that of the blue portion or black portion of the document. It can overcome the disadvantage of conventional electrophotographic photoreceptors that use phthalocyanine as a charge-generating material, which is that the image density is very low compared to the corresponding part, and it is also easy to manufacture, so it can be used for practical purposes. Its value is extremely high.

Claims (1)

[Claims] 1. A charge generation layer containing a phthalocyanine compound as a charge generation material, provided on a conductive substrate;
A photoreceptor for electrophotography comprising a charge transport layer provided on the upper surface of the charge generation layer, wherein the charge transport layer contains a dye having an absorption maximum in the red region of the spectrum.