JPS6320342B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite photographic plate and an electrophotographic method,
In particular, the present invention relates to a composite electrophotographic plate and electrophotographic method having excellent photosensitivity using a novel combination of a charge generating material and a charge transporting material. Conventionally, charge generating substances in composite electrophotographic plates include organic pigments such as quinocyanine pigments, azo pigments, perylene pigments, indigoid pigments, polycyclic quinone pigments, bisbenzimidazole and methine squaritate pigments, and also glassy selenium,
Inorganic materials such as CdS, CdSe, etc., and materials to which Te, As, Cu, In, etc. are added are known. On the other hand, known charge transporting substances include trinitrothioxanthone, polyvinylcarbazole and its derivatives, triarylpyrazoline, trinitrofluorenone, oxazole and its derivatives, and oxadiazole and its derivatives. The various compounds used as charge-generating substances or charge-transporting substances mentioned above all have good electrophotographic properties, but the photosensitivity required for practical use, especially the spectral sensitivity to wavelengths in the visible light region, is was not sufficient, and this was becoming a problem. The purpose of the present invention is to solve the above-mentioned problems of the prior art, and to provide excellent photosensitivity, especially at wavelengths in the visible light region (400
An object of the present invention is to provide a composite electrophotographic plate having excellent photosensitive and spectral characteristics for wavelengths of up to 700 nm). To summarize the present invention, the composite electrophotographic plate of the present invention is a composite electrophotographic plate in which a charge generation material layer and a charge transport material layer are laminated on a conductive substrate, in which the charge generation material is made of CdSe. , and the charge transport substance is a triphenyloxazole compound,
The electrophotographic method of the present invention is characterized by comprising at least one compound selected from the group consisting of a styryl dye base and a cyanine dye base. In an electrophotographic method including a step of developing and developing, a charge generating substance is used as the electrophotographic plate.
A composite electrophotographic plate made of CdSe and in which the charge transport substance is made of at least one compound selected from the group consisting of a triphenyloxazole compound, a styryl dye base, and a cyanine dye base, and the electrophotographic plate is It is characterized by being negatively charged. Although there are still many unknowns about the photosensitive mechanism of composite electrophotographic plates, a charge-generating material absorbs irradiated light to form a light carrier, and then this light carrier, that is, either electrons or holes, is transferred to a charge-transporting material. The mechanisms by which charge transport materials are injected into the layer and migrate through this layer to form a surface charge distribution are generally well known to those skilled in the art. From this principle mechanism, it is clear that in order to inject optical carriers smoothly and without barriers from the charge generating material into the charge transporting material, matching of the energy levels of the two materials is extremely important. That is, for example, when the optical carrier to be injected is an electron, it is advantageous to use a charge transporting material with a large electron affinity because there are fewer barriers during injection.
Similarly, when the optical carrier to be injected is a hole, it is advantageous to use a charge transport material with a small ionization potential. It is not easy to select a charge generating material that has photosensitivity suitable for the visible light region, that is, the ability to generate light carriers. For example, perylene pigments and azo pigments, which have excellent photosensitivity, generally have poor sensitivity to red light above 600 nm, while phthalocyanine pigments are insensitive to colored light below 500 nm. or,
Among inorganic materials, glassy selenium and CdS are excellent in their ability to generate light carriers, but the photosensitive range is
Since it only emits blue light with a wavelength of 500 nm or less, there is a problem in that it is extremely complicated to manufacture, such as the need to add impurities such as Te and Cu. CdSe is the most commonly used material suitable for visible light.
No charge transport material has yet been found that can easily inject photocarriers from charge generating materials. As a result of various studies based on the above findings, the present inventors have found that CdSe is used as a charge-generating substance, and at least one compound selected from the group consisting of a triphenyloxazole compound, a styryl dye base, and a cyanine dye base is used as a charge transport substance. The present invention was completed based on the discovery that excellent sensitivity and spectral characteristics for wavelengths in the visible light region can be exhibited by using a combination of various compounds. When using the electrophotographic plate of the present invention, the optical carriers to be injected are holes, so excellent sensitivity can be obtained by negatively charging the electrophotographic plate in the charging step. In this case, only extremely low sensitivity can be obtained with positive charging. As the conductive substrate in the present invention, brass, aluminum, gold, steel, etc. are used, and these are sheets with appropriate thickness, hardness, or flexibility.
They may be sheet-like and cylindrical, and may be coated with a thin layer of plastic. Also, this is
It may be metal coated paper, metal coated plastic sheet or glass coated with a thin layer of aluminum iodide, copper iodide, chromium oxide, tin oxide or indium oxide. In the present invention, in particular, commonly used aluminum plates and aluminum-coated sheets can be used without special treatment, which is an unparalleled advantage. The charge generating substance in the present invention is CdSe,
It is also possible to improve the characteristics by adding impurities such as Te, Cu, In, and Cl, or by stacking thin films thereof. The layer made of such a charge-generating material can be formed using various methods depending on the purpose and shape, such as vapor deposition, vacuum sublimation, sputtering, electrode reaction, and spraying. Typical examples of triphenyloxazole compounds which are charge transporting substances in the present invention are listed below using structural formulas. Further, typical examples of the styryl dye base, which is a charge transport material in the present invention, are listed below using structural formulas. Further, typical examples of the cyanine dye base which is the charge transport material in the present invention are listed below. When forming a layer, it is advantageous to use the charge transporting substance in the present invention in combination with a suitable binder in order to improve the mechanical strength of the coating film. Such binders include known electrophotographic binder materials such as acrylic resins, butyral resins, polyester resins, polycarbonate resins,
Polyketone resins, polyurethane resins poly-N-vinylcarbazole, poly-9-(p-vinylphenyl)anthracene, and mixtures thereof can be used as appropriate. In addition, the blending amount of these polymer compounds is 1 part by weight of the charge transport material of the present invention.
A suitable range is 0.5 to 10 parts by weight. The film thickness of the charge-generating substance and charge-transporting substance in the present invention is determined based on the charging characteristics required for an electrophotographic plate, but the thickness of the charge-generating substance layer is usually 0.1 to 5 μm.
It is appropriate that the thickness of the charge transport material layer is approximately 5 to 50 μm. If the charge generation material layer is outside the above range, the sensitivity will decrease. In addition, the charge transport material layer
If it is less than 5 μm, the image density will decrease, and if it exceeds 50 μm, the sensitivity will also decrease. Note that, as described above, in the present invention, each charge transporting substance can be used in combination;
If it is difficult to blend them, another layer of charge transporting material may be provided on top of the layer of charge transporting material, if necessary, to achieve the purpose. Next, the present invention will be explained with reference to Examples, but the present invention is not limited to these in any way. Examples 1 to 7 A rolled aluminum plate with a thickness of 2 mm was cut into 50 mm x 50 mm to obtain a conductive substrate. This substrate was cleaned using a neutral detergent, acetone, and trichlene in this order. Four of these substrates were placed in a vapor deposition apparatus, and 0.5 g of Ultrapure CdSe manufactured by Merck was placed in a Mo boat and the entire amount was vapor-deposited. The distance between the boat and the board is 20cm
The deposition rate was monitored using a crystal oscillator.
The speed was adjusted to 40 cps/s. No heating of the substrate was performed. In this way, a deposited film (coat of charge-generating substance) with a thickness of 0.8 μm was formed. Next, 8 g of styryl dye base of the following structural formula, Polyester resin (manufactured by Toyobo Co., Ltd., Byron 200)
A mixed solution of 16 g, 50 ml of 1,2-dichloroethane, and 50 ml of dichloromethane was prepared, and this coating liquid was applied to the above-mentioned CdSe vapor-deposited film using an applicator and dried to form a charge transporting material film with a thickness of about 10 μm. For the composite electrophotographic plate produced in this way, an electrostatic recording paper tester (manufactured by Kawaguchi Electric Co., Ltd., SP-
428), the half-decrease exposure sensitivity using white light as a light source was 10.7 lux sec when negatively charged and 580 lux sec when positively charged, and the injected carrier is a hole. It turns out that it is. A charge generating material layer with a thickness of 5 μm was formed in the same manner as above, and various styryl dye bases shown in Table 1 below were applied as a charge transport material to form a layer with a thickness of 50 μm.
A charge transport material was formed, and the half-decrease exposure sensitivity of the resulting composite electrophotographic plate was measured. The results obtained are also shown in Table 1 below.

【table】

[Table] As is clear from Table 1, all of them exhibited values of around 10 lux·sec or less, and could be fully used as electrophotographic plates. Example 8 A film with a thickness of 0.1 μm was formed in the same manner as in Example 1.
A triphenyloxazole compound represented by the following structural formula was coated on a charge generating substance layer made of CdSe in the same manner as in Example 1, and dried to obtain a film thickness.
A 5μ layer of charge transport material was formed. The spectral sensitivity characteristics of the composite electrophotographic plate thus produced are shown in the graph of the drawing. In addition, as a control, the spectral sensitivity characteristics of an existing electrophotographic plate using a composite type of perylene pigment and oxadiazole derivative, and an electrophotographic plate using a general-purpose mixed compound of polyvinylcarbazole and trinitrofluorenone are also shown in the graph of the same drawing. . That is, curve A in the figure is for this example, curve B is for control 1 when a perylene pigment and oxadiazole derivative is used, and curve C is for control 2 when a mixed compound of polyvinyl carbazole and trinitrofluorenone is used. Indicates the case where
Furthermore, the sensitivity on the vertical axis in the figure is expressed as the reciprocal of the half-reduction exposure sensitivity (in mJ/m ² unit) for each wavelength. As is clear from the drawings, the electrophotographic plate of this example has extremely superior sensitivity and spectral characteristics compared to the control plate. Example 9 A powder prepared by mixing CdSe with 0.1% by weight of Cu and 10% by weight of NH ₄ Cl was fired at about 1000° C. for about 1 hour in a nitrogen stream. The obtained powder was deposited in the same manner as in Example 1 to form a charge generating material layer having a thickness of about 0.5 μm. Next, the structural formula A coating liquid was prepared by blending the triphenyloxazole compound represented by polycarbonate resin (Mitsubishi Gas Chemical Co., Ltd., Iupilon S2000) (weight ratio of 1:1 to the oxazole derivative) and dichloromethane, and the charge generating material layer was It was coated on top and dried to form a layer of charge transport material about 10 μm thick.
The composite electrophotographic plate produced in this manner had extremely high sensitivity, with a half-decrease exposure sensitivity of 1.5 lux·sec when negatively charged. In addition, as a control, composite electrophotographic plates prepared in the same manner as above using three types of known compounds represented by the structural formulas shown in Table 2 below were all found to have low sensitivity or lack of electrical resistance. It is clear from the results in Table 2 that the

[Table] *Measurement Examples 10 to 13 0.4 g of CdSe and 0.2 g of Te were placed in separate boats and deposited to a thickness of 1 μm on Al ₂ O ₃ measuring 50 mm×50 mm. The deposition rate of CdSe is about 5 times that of Te.
The degree of vacuum was 10 ^-5 Torr. Next, this vapor-deposited film was heat-treated at 650° C. for about 1 hour in a nitrogen stream. Next, a styryl dye base, a triphenyloxazole compound, and a cyanine dye base shown in Table 3 below were formed as a charge transport material layer on the vapor deposited film in the same manner as in Example 9. The half-reduced exposure sensitivity of each composite electrophotographic plate obtained when negatively charged was also determined by the third method.
Shown in the table.

【table】

[Table] As is clear from Table 3, all values are sufficient for practical use. Examples 14 and 15 On the charge generating material (CdSe) layer formed in the same manner as in Example 1, triphenyloxazole compounds and cyanine dye bases shown in Table 4 below were vacuum deposited, respectively. The degree of vacuum was 10 ^-3 Torr, and the film thickness was about 1 μm. Furthermore, the same styryl dye base as in Example 1 was coated thereon to produce a composite electrophotographic plate. The half-reduction exposure sensitivity when negatively charged is also shown in Table 4 below.

[Table] As is clear from Table 4, all of the samples exhibited good sensitivity with no practical problems. As explained above, the composite electrophotographic plate of the present invention exhibits high sensitivity and good spectral sensitivity characteristics, and can be applied to the electrophotographic method of the present invention to be used in copiers, laser printers, printing original plates, etc. It can be suitably used.

[Brief explanation of the drawing]

The figure is a graph showing the spectral sensitivity characteristics of composite electrophotographic plates in Example 8 and a control.

Claims (1)

[Scope of Claims] 1. A composite electrophotographic plate comprising a charge generating material layer and a charge transporting material layer laminated on a conductive substrate, wherein the charge generating material is made of CdSe and the charge transporting material is a triphenyloxazole compound. A composite electrophotographic plate comprising at least one compound selected from the group consisting of a styryl dye base and a cyanine dye base. 2. The composite electrophotographic plate according to claim 1, wherein the charge generating material layer has a thickness of about 0.1 to 5 μm, and the charge transporting material layer has a thickness of about 5 to 50 μm. 3 In an electrophotographic method that includes the steps of charging an electrophotographic plate in a dark place, irradiating it with light, and developing it, a charge-generating substance is used as the electrophotographic plate.
A composite electrophotographic plate made of CdSe, in which the charge transport substance is made of at least one compound selected from the group consisting of a triphenyloxazole compound, a styryl dye base, and a cyanine dye base, is used, and the electrophotographic plate is used in the charging step. An electrophotographic method characterized by negatively charging.