JPS6255657B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor containing a styryl anthracene compound as an active ingredient in the photosensitive layer. Conventionally, photoconductive materials for photoreceptors used in electrophotography include inorganic materials such as selenium, cadmium sulfide, and zinc oxide. The "electrophotographic method" referred to here generally involves first charging a photoreceptor in a dark place by corona discharge, and then exposing it to imagewise light to selectively discharge the charge only in the exposed areas, thereby forming an electrostatic latent image. This is one of the image forming methods in which an image is formed by visualizing this latent image area with a developer containing a coloring agent called a toner and electrostatic fine particles made of a binder resin. The basic characteristics required of a photoreceptor in such electrophotography are 1) the ability to be charged to an appropriate potential in a dark place, and 2)
Examples include the fact that there is little charge discharge in a dark place, and the charge is rapidly released by three-light irradiation. Although the conventionally used inorganic materials have many advantages, they also have various disadvantages. For example, selenium, which is currently widely used, fully satisfies conditions 1 to 3 above, but it has strict manufacturing conditions, increases manufacturing costs, and is not flexible, so it cannot be processed into a belt shape. It also has drawbacks such as being difficult and sensitive to heat and mechanical shock, requiring careful handling. Cadmium sulfide and zinc oxide are used dispersed in binding resins, but they have mechanical drawbacks such as smoothness, hardness, tensile strength, and abrasion resistance.
It cannot withstand repeated use as it is. In recent years, electrophotographic photoreceptors using various organic materials have been proposed in order to eliminate the drawbacks of these inorganic materials, and some of them have been put into practical use. For example, poly-N-vinylcarbazole and 2,4,7-
A combination of trinitro-9-fluorenone (U.S. Pat. No. 3,484,237), a sensitized poly-N-vinylcarbazole with a pyrylium salt dye (Japanese Patent Publication No. 48-25658), and organic pigments as main components. (Japanese Unexamined Patent Publication No. 47-37543), and one whose main component is a eutectic complex consisting of a dye and a resin (Japanese Unexamined Patent Publication No. 10735/1982). These photoreceptors certainly have excellent characteristics and are considered to be of high practical value, but considering the various requirements for photoreceptors from the viewpoint of electrophotographic processes, it is still difficult to fully meet these requirements. The reality is that we are not getting anything that satisfies us. On the other hand, although these excellent photoreceptors differ slightly depending on the purpose or manufacturing method, they generally exhibit excellent characteristics by using an excellent photoconductive material. As a result of researching this type of photoconductive substance from the above viewpoints, the present inventors discovered that a styryl anthracene compound represented by the following general formula works effectively as a photoconductive substance for electrophotographic photoreceptors. did. The present inventors previously published Japanese Patent Application Publication No. 51-94829.
Publication No. 51-98260 and patent application No. 53-57962
In the same issue, a styryl anthracene compound having a similar photoconductive effect was proposed, but the styryl anthracene compound of the present invention has a further elongated π-electron skeleton and has excellent compatibility with resins. As described later, the compound of this general formula is
We have discovered that by combining various materials, we can provide photoreceptors with unexpected effects and surprisingly versatile utility. [However, X represents a hydrogen or halogen atom, R ¹ represents a hydrogen or halogen atom, or a C ₁ to _{C 4} alkyl group, a dialkylamino group in which alkyl has 1 to 4 carbon atoms, or a C ₁ to C ₄ alkoxy group. , m is an integer of 1 or 2, and when m is 2, R ¹ may be the same or different. R ² and R ³ are hydrogen atoms, chloroethyl group, hydroxyethyl group, C ₁ -
C ₄ alkyl group or formula

[Formula] (where R ⁴ represents a hydrogen or halogen atom, a C ₁ to C ₄ alkyl group, a C ₁ to C ₄ alkoxy group, or a nitro group, n is an integer of 1, 2, or 3, and n is 2 or 3, R ⁴ may be the same or different.), and at least one of R ² and R ³ is the substituted or unsubstituted benzyl group. It is. ] The styryl anthracene compound of the general formula used in the present invention is dialkyl 9-anthrylmethylphosphonate (however, the number of carbon atoms in the alkyl is 1 to 4)
or dialkyl 10-bromo-9-anthrylmethylphosphonate (however, alkyl has 1 to 4 carbon atoms)
It can be obtained with high purity and high yield by reacting the above aldehydes with aldehydes in the presence of an alkali compound such as an alkali metal hydroxide, amide or alcoholate at a temperature of 10 to 180°C for 15 minutes to 6 hours. Specific examples of the styryl anthracene compound of the general formula thus obtained are as follows.

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[Table] The photoreceptor of the present invention contains the above-mentioned styryl anthracene compounds.
- It can take the form shown in Figure 3. The photoreceptor shown in FIG. 1 has a photosensitive layer 2 comprising the styryl anthracene compound, a sensitizing dye, and a binding resin on a conductive support 1. The photoreceptor shown in FIG. The photoreceptor shown in FIG. 2 has a photosensitive layer 2' on a conductive support 1, in which a charge carrier generating substance 3 is dispersed in a charge transfer medium 4 made of the styryl anthracene compound and a binding resin. be. The photoreceptor shown in FIG. 3 is provided with a photosensitive layer 2'' consisting of a charge carrier generation layer 5 mainly containing a charge carrier generation substance 3 and a charge transfer layer 4 containing the styryl anthracene compound on a conductive support 1. In the photoreceptor shown in Fig. 1, the styryl anthracene compound acts as a photoconductive substance, and the generation and transfer of charge carriers necessary for light attenuation occur through this styryl anthracene compound. Anthracene compounds have almost no absorption in the visible range, so for the purpose of forming images, it is necessary to sensitize them with a sensitizing dye that has absorption in the visible range. In this case, the styryl anthracene compound together with the binder (and optionally the plasticizer) forms the charge transport medium, while the charge carrier generating material, such as an inorganic or organic pigment, generates the charge carriers. The medium primarily has the ability to accept and transport charge carriers generated by the charge carrier generating substance.
The basic condition here is that the absorption wavelength regions of the charge carrier generating substance and the styryl anthracene compound do not overlap with each other, mainly in the visible region. This is because in order to efficiently generate charge carriers in the charge carrier generating material, it is necessary to transmit light to the surface of the charge carrier generating material. The styryl anthracene compound of the present invention has almost no absorption in the visible region, and when combined with a charge carrier generating substance that generally absorbs light in the visible region and generates charge carriers, it works particularly effectively as a charge transfer medium. have. In addition, in the photoreceptor shown in FIG. 3, light transmitted through the charge transfer layer 4 reaches the charge carrier generation layer 5, where charge carriers are generated, while the charge transfer layer does not allow injection of charge carriers. The mechanism in which the charge carriers necessary for photoattenuation are generated by a charge carrier generating substance, and the charge carriers are transferred by a charge transfer medium (mainly in which the styryl anthracene compound of the present invention works) is as follows. 2
This is the same as the case of the photoreceptor shown in the figure. Again, the styryl anthracene compound acts as a charge transfer substance. To prepare the photoreceptor shown in FIG. 1, the styryl anthracene compound is dissolved in a binder solution, and a sensitizing dye is added as necessary.
The photosensitive layer 2 may be formed by coating and drying the photosensitive layer 2 thereon. To make the photoreceptor shown in FIG. 2, fine particles of the charge carrier generating substance 3 are dispersed in a solution containing the styryl anthracene compound and a binder, and this is coated on the conductive support 1 and dried to form the photosensitive layer 2. ′ can be formed. In the case of the photoreceptor shown in FIG. 3, the charge carrier generating substance 3 (a) is vacuum-deposited on the conductive support 1, or the fine particles of the charge carrier generating substance 3 (b) are placed in a solution containing a binder dissolved therein. The charge carrier generating layer 5 is formed by dispersing, applying and drying the layer, and if necessary, finishing the surface by a method such as buffing or adjusting the thickness, and then applying the styryl anthracene compound and crystals thereon. The charge transfer layer 4 may be formed by applying and drying a solution containing an adhesive. Application is carried out by conventional means, such as a doctor blade or wire bar. In the above photoreceptor, the thickness of the photosensitive layer is about 3 to 100 μm, preferably 5 μm in the case of those shown in FIGS.
~30μ is appropriate. In addition, in the case of FIG. 3, the thickness of the charge carrier generation layer is 0.05 to 20μ, preferably 0.1 to 20μ.
5μ and the thickness of the charge transport layer is about 3 to 100μ, preferably 5 to 30μ. In addition, in the photoreceptor shown in FIG. 1, the proportion of the styryl anthracene compound in the photosensitive layer is 30 to 70% of the weight of the photosensitive layer, preferably about
50% is appropriate. The sensitizing dye used to impart photosensitivity in the visible region accounts for 0.1 to 5 of the weight of the photosensitive layer.
%, preferably 0.2 to 3%. Next, the proportion of the styryl anthracene compound in the photosensitive layer of FIG. 2 is 10 to 95% by weight, preferably 30 to 90% by weight, and the proportion of the charge carrier generating substance is 1 to 50% by weight, preferably 1 to It is 20% by weight. Further, in the photoreceptor shown in FIG. 3, the proportion of the styryl anthracene compound in the charge transfer layer is 10 to 95% by weight, preferably 30 to 90% by weight, as in the case of the photoreceptor shown in FIG. In addition, in any of the photoreceptors shown in FIGS. 1 to 3, a plasticizer can be used together with a binder. In the photoreceptor of the present invention, the conductive support may be a metal plate or metal foil such as aluminum, a plastic film on which metal such as aluminum is vapor-deposited,
Alternatively, conductive treated paper, plastic film, etc. may be used. Examples of binders include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, and polyacrylamide. In addition, any adhesive resin can be used. Examples of the plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. In addition, the sensitizing dyes used in the photoreceptor shown in FIG.
Xanthene dyes such as 6G, Rhodamine G Extra, Eosin S, Erythrosin, Rose Bengal, Fluorethcene; Thiazine dyes such as methylene blue; Cyanine dyes such as cyanine;
Examples include pyrylium dyes such as 2,6-diphenyl-(N,N-dimethylaminophenyl)thiapyrylium perchlorate and benzopyrylium salts described in Japanese Patent Publication No. 48-25658. The charge generating substance used in FIGS. 2 and 3 is a pigment capable of generating charge carriers by irradiation with light, and it is particularly effective to use, for example, the following azo pigment. Azo pigments having a carbazole skeleton (for example, described in Japanese Patent Application No. 52-8740 or 52-8741) Azo pigments having a styrylstilbene skeleton (for example, described in Japanese Patent Application No. 52-48859) Azo pigments having a triphenylamine skeleton Pigments (for example, described in Japanese Patent Application No. 52-45812) Azo pigments having a dibenzothiophene skeleton (for example, described in Japanese Patent Application No. 52-86255) Azo pigments having an oxadiazole skeleton (for example, described in Japanese Patent Application No. 52-86255) -77155) Azo pigments having a fluorenone skeleton (for example, described in Japanese Patent Application No. 52-87351) Azo pigments having a stilbene skeleton (for example, described in Japanese Patent Application No. 52-81790) Distyryloxadiazole skeleton (For example, described in Japanese Patent Application No. 52-66711) Azo pigments having a distyrylcarbazole skeleton (For example, described in Japanese Patent Application No. 52-81791) In addition to these azo pigments, generally The following known substances can also be used as charge carrier generating pigments. For example, selenium, selenium
Inorganic pigments such as tellurium, cadmium sulfide, cadmium-selenium sulfide, and organic pigments include, for example, seaweed.
Eye pigment blue 25 (color index)
Azo pigments such as CI Pigment Red 41 (CI21200), CI Pigment Red 52 (CI45100), CI Basic Cred 3 (CI45210), CI Pigment Blue 16 Phthalocyanine pigments such as (CI74100), Sea Butt Brown 5
Examples include organic pigments such as perylene pigments such as Indigo Scarlet B (CI73410), CI Butt Dye (CI73030), Indigo Scarlet R and the like. In any of the photoreceptors obtained as described above, an adhesive layer or a barrier layer can be provided between the conductive support and the photosensitive layer. Suitable materials for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the layer thickness is preferably about 0.01 to 2 .mu.m. To perform copying using the photoreceptor of the present invention, the surface of the photosensitive layer is charged and exposed in a conventional manner, then developed, and if necessary, the image is transferred to a transfer paper such as high-quality paper. The photoreceptor of the present invention generally has excellent advantages such as high sensitivity and flexibility. Examples are shown below. All parts are by weight. Example 1 98 parts of tetrahydrofuran were added to 2 parts of Diane Blue (CI21180), and the mixture was ground and mixed in a ball mill to obtain a charge carrier-generating pigment dispersion. This was applied onto a polyester film deposited with aluminum using a doctor blade, and air-dried to form a charge carrier generation layer having a thickness of 1 μm. Next, a charge transfer layer forming liquid obtained by mixing 2 parts of the styryl anthracene compound represented by Compound No. 16, 3 parts of polycarbonate (Panlite L manufactured by Teijin), and 45 parts of tetrahydrofuran was applied to the above charge carrier generation layer with a doctor. The photoreceptor of the present invention was prepared by applying the coating using a blade and drying at 100° C. for 10 minutes to form a charge transfer layer with a thickness of 9 μm. This photoreceptor was tested using an electrostatic copying paper tester (KK Kawaguchi Electric Seisakusho, SP428 model).
After applying 6KV corona discharge for 20 seconds to make it negatively charged, leave it in a dark place for 20 seconds, and then measure the surface potential.
Measure Vpo (V), then irradiate the surface with light using a tungsten lamp at an illuminance of 20 lux, and calculate the time (seconds) it takes for the surface potential to become 1/2 of Vpo during exposure. The quantity E1/2 (lux seconds) was obtained. The result is Vpo=1200V, E1/
2 = 2.5 lux seconds. Example 2

[Table] A charge carrier-generating pigment dispersion is obtained by pulverizing and mixing the liquid in a ball mill. This was applied onto a polyester film deposited with aluminum using a doctor blade, and dried for 5 minutes in a dryer at 80° C. to form a charge carrier generation layer with a thickness of 1 μm. Next, a charge transfer layer forming liquid obtained by mixing 2 parts of the styryl anthracene compound represented by Compound No. 18, 3 parts of polycarbonate (Panlite L), and 45 parts of tetrahydrofuran was applied onto the charge carrier generation layer with a doctor blade. Apply using
The photoreceptor of the present invention was prepared by drying at 100° C. for 10 minutes to form a charge transfer layer with a thickness of 10 μm. This photoreceptor was negatively charged in the same manner as in Example 1, and Vpo and E1/2 were measured.
= 1050V, E1/2 = 4.5 lux seconds. Example 3 In the same manner as in Example 2, as a charge carrier generating pigment When a styryl anthracene compound represented by Compound No. 10 was used as a charge transfer agent, Vpo=950V and E1/2=9.5 Lux·sec. Example 4 In the same manner as in Example 2, as a charge carrier generating pigment When a styryl anthracene compound represented by Compound No. 27 was used as a charge transfer agent, Vpo=920V and E1/2=1.3 Lux·sec. Next, the photoreceptors obtained in Examples 1 to 4 were negatively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image, followed by dry development with positively charged toner. The image was developed using a chemical agent, and the image was electrostatically transferred to high-quality paper and fixed to obtain a clear image. A similarly clear image was obtained when a wet type developer was used as the developer. Example 5 On an aluminum plate with a thickness of about 300 μm, selenium was vacuum-deposited to a thickness of 1 μm to form a charge carrier generation layer. Next, 2 parts of the styryl anthracene compound represented by Compound No. 1, polyester resin (manufactured by DuPont, Polyester Adhesive)
49000) and 45 parts of tetrahydrofuran to prepare a charge transfer layer forming liquid, apply this onto the above charge carrier generation layer (selenium vapor deposition layer) using a doctor blade, air dry, and then apply under reduced pressure. A charge transfer layer having a thickness of 10 μm was formed by drying the photoreceptor of the present invention. This photoconductor was prepared in the same manner as in Example 1, and Vpo
When measuring and E1/2, Vpo=1200V,
E1/2=9.0 lux·sec. Example 6 Perylene pigment in place of selenium in Example 5 is vacuum deposited to a thickness of 0.3μ to form a charge carrier generation layer. Next, a photoreceptor was prepared in the same manner as in Example 5 except that the charge transfer agent was replaced with a styryl anthracene compound represented by compound No. 24.
Vpo=790V, E1/2=10.5 Lux・sec. Next, the photoreceptors obtained in Examples 5 and 6 were negatively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image.A dry developer containing positively charged toner was then used. The image was electrostatically transferred to high-quality paper and fixed to obtain a clear image. A similarly clear image was obtained when a wet type developer was used as the developer. Example 7 A mixture of 1 part of β-type copper phthalocyanine and 158 parts of tetrahydrofuran was pulverized and mixed in a ball mill. The photosensitive layer forming solution obtained by adding 18 parts of 49000) and mixing further was applied onto an aluminum-deposited polyester film using a doctor blade, dried at 100℃ for 30 minutes, and the thickness was determined.
A photoreceptor of the present invention was prepared by forming a 16 μm photosensitive layer. This photoreceptor was positively charged by +6KV corona discharge using the same device as used in Example 1, and Vpo and E1/2 were similarly measured.Vpo=820V, E1/2=11.5 It was lux second. Example 8 In the same manner as in Example 7, as a charge carrier generating pigment When a styryl anthracene compound represented by Compound No. 17 was used as a charge transfer agent, Vpo=1320V and E1/2=9.5 Lux·sec. Example 9 In the same manner as in Example 7, as a charge carrier generating pigment When a styryl anthracene compound represented by compound No. 25 was used as a charge transfer agent, Vpo=990V and E1/2=7.4 lux·sec. Example 10 In the same manner as in Example 7, as a charge carrier generating pigment When a styryl anthracene compound represented by Compound No. 30 was used as a charge transfer agent, Vpo was 1320 V and E1/2 was 3.5 lux·sec. Next, the photoreceptors obtained in Examples 7 to 10 were positively charged by applying a +6KV corona discharge using a commercially available electrophotographic copying machine, and then irradiated with light through the original image to form an electrostatic latent image. The image was developed using a dry developer containing negatively charged toner, and the image was electrostatically transferred and fixed onto high-quality paper to obtain a clear image. Similarly good results were obtained when a wet type developer was used as the developer. Example 11 A solution consisting of 10 parts of styryl anthracene compound represented by Compound No. 5, 0.02 parts of Rhodamine B Extra, 10 parts of polyvinyl chloride (SG1100 manufactured by Nippon Carbide Co., Ltd.), and 70 parts of toluene was treated in advance to prevent seepage with organic solvents. Apply evenly on transparent paper and dry until thick.
A 10μ photosensitive layer was provided. Next, the obtained photoconductor is negatively charged by applying corona discharge of -6KV using a commercially available electrophotographic copying machine, and then light is irradiated through the original image to form an electrostatic latent image, and then a positively charged toner is charged. A second original copy having a clear image was obtained by developing and fixing the image using a dry developer having the following properties.

[Brief explanation of the drawing]

1 to 3 are enlarged sectional views of a photoreceptor according to the present invention. 1... Conductive support, 2, 2', 2''... Photosensitive layer, 3... Charge carrier generating substance, 4... Charge transport layer, 5... Charge carrier generating layer.

Claims (1)

[Claims] 1. General formula on a conductive support [However, X represents a hydrogen or halogen atom, R ¹ represents a hydrogen or halogen atom, or a C ₁ to _{C 4} alkyl group, a dialkylamino group in which alkyl has 1 to 4 carbon atoms, or a C ₁ to C ₄ alkoxy group. , m is an integer of 1 or 2, and when m is 2, R may be the same or different. R ² and R ³ are hydrogen atoms, chloroethyl group, hydroxyethyl group, C ₁ to _{C 4}
or an alkyl group of the formula [Formula] (where R ⁴ represents a hydrogen or halogen atom, a C ₁ to C ₄ alkyl group, a C ₁ to _{C 4} alkoxy group, or a nitro group, and n is 1, 2 or 3. is an integer, and when n is 2 or 3, R ⁴ may be the same or different.) represents a substituted or unsubstituted benzyl group, and at least one of R ² and R ³ is the substituted or It is an unsubstituted benzyl group. ] A photoreceptor for electrophotography, comprising a photosensitive layer containing at least one styryl anthracene compound as an active ingredient.