JPS6255782B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic light-sensitive material, and more particularly to a laminated electrophotographic light-sensitive material comprising a charge generation layer made of a novel polymethine dye and a charge transport layer. In recent years, many electrophotographic photoreceptors have been proposed that combine a substance that generates charge carriers when exposed to light (referred to as a charge-generating material) and a material that can transport the generated charge carriers (referred to as a charge-transfer material). has been done. For example, US Pat. No. 3,791,826 discloses a photoreceptor in which a charge transport layer is provided on a charge generation layer, and US Pat. No. 3,573,906 discloses a photoreceptor in which a charge generation layer is provided on a charge transport layer. Each is listed. Conventional electrophotographic materials include amorphous selenium,
Inorganic materials such as selenium alloys, cadmium sulfide, and zinc oxide, and organic materials such as polyvinylcarbazole are widely known. It is well known that amorphous selenium or selenium alloys have extremely excellent properties as electrophotographic light-sensitive materials and have been widely used in practical applications. However, the sensitive wavelength range of amorphous selenium and the like is in the blue region, and has little or no sensitivity in the red or infrared region. Additionally, various methods have been proposed to extend photosensitivity to longer wavelength regions;
There are many restrictions on the selection of the sensitive wavelength range, and photosensitivity to long wavelength light is not sufficient. The same applies when zinc oxide or cadmium sulfide is used as a photosensitive material. Organic materials have many superior properties compared to inorganic materials, and have a wide range of applications in the field of electrophotography. For example, it is only possible to produce a transparent photosensitive film, a flexible photosensitive film, or a light and easy-to-handle photosensitive film using organic materials.
In addition, film formation properties, surface smoothness, and
Furthermore, it has properties that cannot be expected from inorganic materials, such as selectivity in charging polarity when applied to electrophotographic processes. Although organic materials have excellent properties in many respects, to date they have not been able to contribute sufficiently to the technical field of electrophotography, mainly due to their low photosensitivity. . For example, polyvinylcarbazole itself has the drawback of having almost no sensitivity in the visible light region, and cannot be put to practical use as it is, so various sensitization methods have been proposed. The most commonly known methods of sensitization are the addition of sensitizing dyes and the addition of Lewis acids, which can be applied to most organic materials without exception; By adding spectral absorption properties to an organic material, the latter brings about sensitization due to the appearance of new spectral sensitivity due to the formation of a donor-acceptor complex with the organic material. However, even when organic materials are sensitized by the above-mentioned conventional method, the sensitive wavelength range is limited and the sensitivity is still insufficient, making it impractical as a photoreceptor for electrophotography.
The same can be said of inorganic materials. By using a new polymethine dye in the charge generation layer, inorganic, organic, or organic-inorganic 2
It has been found that a highly sensitive electrophotographic material whose photosensitive wavelength range extends to infrared rays can be obtained. An object of the present invention is to provide a highly sensitive panchromatic photosensitive material that can be used in any electrophotographic process and is sensitive to all visible wavelengths and in the infrared region up to around 1200 nm. . In particular, it is an object of the present invention to provide a light-sensitive material for a system using a semiconductor laser as a light source. The present invention was achieved by using a polymethine dye represented by the following general formula () in the charge generation layer in a laminated electrophotographic material having a charge generation layer and a charge transport layer on a conductive support. . General formula () [However, A, B, D, and E are phenyl (including substituted phenyl), Y is a divalent residue necessary to form a 5- or 6-membered ring, and R is hydrogen or halogen. Yes, and X represents an anionic residue. ] The above polymethine dye is a new compound, but it can be synthesized by a conventionally known method. For example, Bernard S. Wildi et al., J. Am. Chem.
Sec (Journal of American Chemical Society) 80 3772-3777 (1958) and
It is described in detail in R. Wizinger et al., Helv.Chim.Acta (Krepeteica simica acta) 24 369E. Next, the synthesis of the polymethylene dye having the above general formula () will be briefly described. Synthesis example 3.4 g of 2-chloro-1-formyl-3-hydroxymethylenecyclohexene (melting point 115-116°C, synthesized using cyclohexanone with dimethylformamide and phosphorus oxychloride) and 1.1-bis-
(4-diethylaminophenyl)ethylene 13.0g
Dissolve in 30ml of acetic acid and add 70% perchloric acid aqueous solution to this.
A solution of 3.0 g dissolved in 30 ml of acetic anhydride is added dropwise at room temperature. Stirring was performed for 1 hour on an oil bath with a post-bath temperature of 90°C. After the reaction is complete, add 200ml of isopropyl ether to form a powder. This powder was recrystallized from ethanol to obtain 5.3 g of powder with metallic luster. The melting point was 180-181°C. ^ETOH 〓 _nax =1055 nm, 715 nm The dyes shown below are also synthesized according to the above synthesis example. The present invention provides a highly sensitive infrared-sensitive electrophotographic material by using the polymethine dye as a charge-generating substance and combining it in a laminated manner with a layer having a charge-transfer function. The charge generation layer made of the polymethine dye described above may be provided on the conductive support and may be provided either above or below the charge transport layer. The conductive support used in the present invention is a metal plate or sheet made of aluminum, copper, zinc, etc., a plastic sheet or plastic film made of polyester, etc., and aluminum, SnO ₂
Examples include those made by vapor-depositing and laminating conductive materials, such as glass plates, plastic films, paper, etc., which are subjected to various conductive treatments. When using an opaque inorganic material such as zinc oxide for the charge transport layer and placing it on top of the charge generation layer (on the side far from the support), the conductive support should be transparent so that it can be exposed from the back side. Preferably a sexual one. In the charge generation layer, the dye can be used dispersed in a binder, or the dye can be used alone. Alternatively, a thin layer of dye may be formed by vacuum deposition to form a charge generation layer, a solution in which the dye is dissolved (which may also contain a binder) may be applied, or the dye may be ground in a dispersion solvent to create a charge generation layer. In either case, it is effective to apply a mixture of a pigment and a dye to form a charge generation layer. In particular, favorable results are obtained when the polymethine dye used in the present invention is applied after being dissolved in a dye solvent that may contain a binder. When used dissolved or dispersed in a binder, it is usually 1 to 500% by weight based on the binder.
Added. In the case of dispersion, the dye is 5 μm or less,
Preferably, particles are 1 μm or less. As the binder for the charge generation layer, known binder resins can be used. Specifically, polyester, styrene resin, acrylic resin, polyurethane, epoxy resin, polyamide, polyvinylcarbazole and its derivatives or their derivatives or their compounds with chemical sensitizers, polyvinyl butyral, polycarbonate, styrene-butadiene copolymer, silicone resin. , styrenated alkyd resin, polyrifenylene oxide resin, phenoxy resin, diallyl phthalate resin, polysulfone resin, xylene resin and the like. Alcohol-soluble polyamides have been found to be particularly preferred in the present invention. Alcohol-soluble polyamide is a polyamide that has high solubility in solvents, especially lower alcohols, and is specifically synthesized from dibasic fatty acids, diamines, ω-amino acids, lactams, or derivatives thereof by known methods. It is a linear polyamide with
Not only homopolymers but also copolymers, block polymers, etc. can be used. Alcohol-soluble polyamides are detailed in, for example, JP-A-54-39802, and specifically include copolymerized nylon “Uitramid IC” manufactured by BASF, “Aramin CM4000” and “Aramin CM8000” manufactured by Toray Industries, Inc. It is available under the trade name. As the solvent for the polymethine dye used in the present invention, for example, methyl alcohol, ethyl alcohol benzene, toluene, xylene, monochlorobenzene, dioxane, dichloroethane, methyl ethyl ketone, etc., or a mixed solvent thereof can be used. Moreover, the polymethine dye used in the present invention can be dissolved using a co-solvent. Examples of the co-solvent include dimethylformamide, acetylacetone, dimethyl sulfoxide and the like. When using pigment particles as described above dispersed in a binder, it is necessary to use a dispersion solvent that dissolves the binder resin but does not dissolve the pigment particles. The charge generation layer in the present invention has, for example, 10 ^-3 to
Vacuum deposition is performed by heating the dye to a temperature below its decomposition point under a vacuum of 10 ^-5 mmHg, and a homogeneous dye layer can be obtained. Further, when forming a dye layer by a method of pulverizing and coating, pulverizing can be performed using a ball mill or the like. As a coating method, known methods such as an applicator method, a spray method, a bar coater method, and a dip coat method can be used. The charge generation layer in the present invention has a thickness of 0.005
The thickness is in the range of 10 μm, preferably 0.005 to 5 μm. The charge transport layer in the present invention does not necessarily have the function of transporting both electrons and holes, but the object of the present invention can be achieved as long as it has the function of transporting either one of the charges. In addition, the charge transport layer may be formed by a polymer compound that itself has film-forming ability and charge transport function, or it may be formed by dispersing a charge transport material that does not have film-forming ability in itself in a binder. It is formed by letting As the charge transport material, the inorganic materials mentioned above can be used, and for example, the following organic materials can be preferably used. (1) Aromatic tertiary amino compounds: triphenylamine, dibenzylaniline, di-(P-chlorobenzyl)aniline, etc. (2) Aromatic tertiary diamino compound: N・N・
N′・N′-tetrabenzyl-p-phenylenediamine, N・N・N′・N′-tetrabenzyl-
m-phenylenediamine, N・N・N′・N′-
tetraphenyl-m-phenylenediamine,
4,4'-benzylidine-bis(N,N-diethyl-m-toluidine), etc. (3) Aromatic tertiary triamino compound: 4・4′・
4″-tris(diethylaminophenyl)methane, 4-dimethylamino-4′・4″-bis(diethylamino)-2′・2″-dimethyl-triphenylmethane, etc. (4) Polyvinylcarbazole compound: polyvinylcarbazole, Halogen-substituted polyvinylcarbazole, copolymer of vinylcarbazole and styrene, copolymer of vinylcarbazole and vinylanthracene, etc. (5) Condensation products: condensation products of aldehydes and aromatic amines, tertiary aromatic amines and aromatic (6) Metal-containing compounds: Salts of 2-mercapto-benzothiazole and mercapto compounds such as lead, zinc or copper salts with metals, metal salts of 8-hydroxy-quinoline, etc. (7) Heterocyclic compound: 1,5-diphenyl-3-styryl-pyrazoline, 1,3-diphenyl-5
Pyrazoline derivatives such as -(P-dimethylaminophenyl)-pyrazoline, 3-(4'-dimethylaminophenyl)-5,6-di-(4'-methoxyphenyl)-1,2,4-triazine triazine derivatives such as, quinazoline derivatives such as 2-phenyl-4-(4'-dimethylaminophenyl)-chitozoline, benzofurans such as 6-hydroxy-2-phenyl-3-(P-dimethylaminophenyl)-benzofuran. Derivative, 2.5-
Bis-[4'-dimethylaminophenyl-(1')]-
Examples include oxadiazole derivatives such as 1,3,4-oxadiazole. When using a binder, for example, a binder resin as described above can be used. The ratio of charge transport material to binder is e.g. 30-300
It can be used in weight percent. The thickness of the charge transport layer is approximately 5 to 100 microns. Other types of dyes and chemical sensitizers typified by Lewis acid compounds can also be added to the light-sensitive material of the present invention. For example, pigments include triphenylmethane-based pigments such as Victoria Blue B and Crystal Violet, diphenylmethane-based pigments such as Auramine G, xanthene-based pigments such as Rhodamine G, azine-based pigments such as methylene violet BN, and 2,6-di(4- dimethylaminostyryl)-4-phenylbenzopyrylium-perchlorate, 2,4,6-
Pyrylium dyes such as tri(dimethylaminophenyl)-thiapyrylium-perchlorate can be used. As chemical sensitizers, P-nitrophenol, P-nitrobenzoic acid, 4-chloro-3.5-
Dimethylphenol, 4-hydroxy-3-promo-bisphenylbis(5-chloro-2-hydroxyphenyl)methane, N・N'-diethyl-2
-thiobarbituric acid, N・N′-dimethyl-barbituric acid, N・N′-dibenzyl-2-thiobarbituric acid, N-(n-butyl)-N′-(P-
It can also contain compounds such as chlorophenyl)barbituric acid, 3-chlorobenzoylacetanilide, 3,5-dichlorobenzoylaceto-(3',5'-dichloroanilide)malondianilide, tetracyanoquinodimethane, picric acid, etc. . Furthermore, for the purpose of further improving mechanical strength, plasticizers such as chlorinated paraffin, phthalate type and phosphate type plasticizers can be added. Next, the present invention will be explained with reference to examples, but it goes without saying that the present invention is not limited to these examples. Examples 1 to 5 On a polyethylene terephthalate film support laminated with aluminum, 1 part by weight of alcohol-soluble nylon "Amilan CM-8000" manufactured by Toray Industries, Inc. and 0.15 parts by weight of the polymethine dye of the present invention were added to n-
1.0 after drying the solution dissolved in propyl alcohol
A charge generation layer was provided by applying the coating to a thickness of .mu.m. Next, 1-(P-ethoxyphenyl)-3-(P-ethoxystyryl)-5 was added to these charge generation layers.
A coating solution in which equal amounts of -phenyl-pyrazoline and polyester resin "Pylon #200" manufactured by Toyobo Co., Ltd. were dissolved was coated in layers to a dry film thickness of 10 μm and dried. After cleaning a part of the photosensitive layer surface of each of these samples to expose the aluminum surface and treating it so that it can be grounded, the maximum spectral sensitivity was measured using a monochromator, and the surface potential and surface potential were halved. The energy (E1/2μ joul/cm ² ) required for this is shown in Table 1. Further, the maximum spectral sensitivity wavelength (nm) and maximum reflection wavelength (nm) are shown in Table 1. Incidentally, the polymethine dyes used in this example were the following five types from among the above-mentioned exemplified dyes.

[Table] From the results in Table 1, it can be seen that the sensitizing dyes of the present invention, except for some (Example 2), are dyes that provide excellent sensitization in the near-infrared sensitive region. Example 6 On a polyethylene terephthalate film support coated with aluminum, 0.1 part by weight of polymethine dye No. 12 of the present invention was dissolved in 50 ml of ethanol and applied to a film thickness of 0.3 μm after drying to form a charge generation layer. Ta. Next, 2 g of 2,2-bis-(4-N-N-dibenzylaminophenyl)-butane (the following structural formula) was added to this charge generation layer. A solution of 1.8 g of polycarbonate resin and 0.1 g of N·N'-diethyl-2-thiobarbituric acid dissolved in 10 g of dichloroethane was coated in a layered manner and dried under heating to form a charge transfer layer with a thickness of 8 μm. The photoreceptor prepared in this way was installed in an electrometer SP-428 model manufactured by Kawaguchi Electric Co., Ltd., and the voltage applied to the charger discharge electrode was set to -6 KV, and the potential after 10 seconds of charging operation was measured.
Vo (volt) and the amount of irradiation light E1/2 (lux·sec) required to reduce Vo by half were determined. In addition, these charging-exposure cycles were repeated 1000 times using the same device, and the potential Vo' (volt) for the 1000th time and the amount of irradiation light E'1/2 (lux sec) required to halve Vo' were determined. . The results are shown in Table 2.

[Table] From the results shown in the table above, it can be seen that the dye of the present invention undergoes almost no optical deterioration or electrical deterioration due to repeated charging-exposure operations. In this example, the relatively poor sensitivity E1/2 of the laminated structure photoreceptor is thought to be due to the discrepancy between the wavelength of the light source of the electrometer SP-428 model and the spectral sensitivity of this photoreceptor. It will be done. Example 7 500nm to 1300nm of photoreceptor made with laminated type 6
The energy required to reduce the initial potential Vo (approximately 1000 to 1200 volts) by half was measured using a monochromator and is illustrated as a spectral sensitivity curve.
Further, the reflection spectrum of this photoreceptor was measured using a spectrophotometer UV-365 manufactured by Shimadzu Corporation and is similarly illustrated. Incidentally, curves with almost the same tendency were obtained even when the charging was different.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram showing the spectral sensitivity and reflection spectrum in the range from 500 nm to 1300 nm of a photoreceptor using the dye of the present invention as a charge generation layer in Example 7.

Claims (1)

[Scope of Claims] 1. An electrophotographic light-sensitive material characterized in that a charge transport layer and a charge generation layer containing a dye represented by the following general formula (2) are laminated on a conductive support. General formula () [However, A, B, D, and E are phenyl (including substituted phenyl), Y is a divalent residue necessary to form a 6-membered ring or a 5-membered ring, and R is hydrogen or halogen. Yes, and X represents an anionic residue. ] 2 In the dye represented by the general formula () according to item 1, A and D or all A, B, D, and E are [Formula] [R ₁ and R ₂ are lower alkyl, benzyl (including substituted benzyl) )] is an electrophotographic photosensitive material. 3. The electrophotographic material according to claim 1, wherein the charge generation layer contains alcohol-soluble polyamide as a binder.