JPH0542661B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a specific styryl compound in its photosensitive layer. Prior Art Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been used as photoconductive materials for photoreceptors used in electrophotography. The "electrophotographic method" referred to here generally refers to a method in which a photoconductive photoreceptor is first charged in a dark place, for example, by corona discharge, and then exposed imagewise to selectively dissipate the charge only in the exposed areas. An electrostatic latent image is obtained, and this latent image area is developed and visualized with electrostatic fine particles (toner) consisting of a coloring material such as a dye or residual material and a binder such as a polymeric substance to form an image. This is one of the image forming methods. The basic characteristics required of the photoreceptor in such electrophotography are (1) ability to be charged to an appropriate potential in the dark, (2) low charge dissipation in the dark, (3) For example, the charge can be quickly dissipated by light irradiation. Incidentally, while each of the above-mentioned inorganic substances has many advantages, it is also true that they also have various disadvantages. For example, selenium, which is currently widely used, fully satisfies conditions (1) to (3) above, but the manufacturing conditions are difficult, the manufacturing cost is high, it is not flexible, and it cannot be processed into a belt shape. It also has disadvantages, such as being difficult to handle and being sensitive to heat and mechanical shock, requiring careful handling.
Cadmium sulfide and zinc oxide are used as photoreceptors by being dispersed in resin as a binder.
It cannot be used repeatedly as it is because of mechanical defects such as smoothness, hardness, tensile strength, and abrasion resistance. 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-vinylcarbasol and 2,4,
7-trinitrofluoren-9-one (described in U.S. Pat. No. 3,484,237), a photoreceptor made by sensitizing poly-N-vinylacarbasol with a pyrylium salt dye (Tokuko Showa) 48-25658), a photoreceptor whose main component is an organic pigment (described in JP-A-47-37543), a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin (JP-A-47-37543), a photoreceptor whose main component is a eutectic complex consisting of a dye and a resin Showa 47-
(described in Publication No. 10735). Although these photoreceptors have excellent properties and are considered to be of high practical value, considering the various requirements for photoreceptors in electrophotography, it is still difficult to fully meet these requirements. The reality is that we are not getting anything that satisfies us. However, all of the photoreceptors mentioned so far differ depending on the purpose or manufacturing method, but in general, good characteristics can be obtained by using excellent photoconductive materials. be. Purpose It is an object of the present invention to provide a photoreceptor that can eliminate the various drawbacks of the conventional photoreceptors mentioned above and fully satisfy the conditions required in electrophotography. Another object of the present invention is to provide an electrophotographic photoreceptor that is easy to manufacture, relatively inexpensive, and has excellent durability. Structure As a result of research and consideration on many photoconductive substances, the inventor found the following general formula () (In the formula, R ¹ represents an alkyl group containing a substituted alkyl group or an aryl group containing a substituted aryl group, and R ²
represents a hydrogen atom, an alkyl group containing a substituted alkyl group, or an aryl group containing a substituted aryl group,
Ar represents an aryl group including a substituted aryl group. ) has been found to work effectively as a photoconductive substance for electrophotographic photoreceptors. Furthermore, it has been found that this styryl compound can be combined with various materials to create photoreceptors with unexpected effects, as will be apparent from the description below. The present invention was completed based on these findings. That is, the present invention provides an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive support, characterized in that the photosensitive layer contains a styryl compound represented by the above general formula (). It is. The styryl compound represented by the above general formula () used in the present invention is the following general formula () (In the formula, YX is

It is a phosphonium group represented by the formula: (wherein Z represents a halogen ion) or a dialkyl phosphorous group represented by -PO(OR) ₂ (wherein, R represents a lower alkyl group). ] Phosphorus compound represented by and the following general formula () (In the formula, R ¹ represents an alkyl group including a substituted alkyl group or an aryl group including a substituted aryl group.) Aryl groups in the above formula include phenyl, styryl, biphenyl, naphthyl, and anthryl groups, and substituents in these include alkyl, alkoxy, aryloxy, halogen, dialkylamino, and hydroxyl groups. group, a carboxy group or an ester thereof, a nitro group, an acetyl group, or a cyano group. Next, a manufacturing example will be shown. Production example 1 4,4'-diformyltriphenylamine 1.51g
and diethyl 1,1-diphenylmethylphosphonate
Dissolve 3.04g in 20ml of N,N-dimethylformamide, and add 1.68g of potassium t-butoxide to 25ml of N,N-dimethylformamide.
Added at ~35°C. After the addition, the mixture was stirred at room temperature for 3 hours, and then the contents were poured into ice water, and the resulting precipitate was filtered, washed with water, and dried. The yield was 2.77g. This was recrystallized from a mixed solvent of ethyl acetate and ethanol, and 4,4'-bis(β
-Phenylstyryl) triphenylamine was obtained in pure form. The melting point of the obtained crystals was 156.0-157.0°C. The elemental analysis values were as shown in the table below.

[Table] Specific examples of the styryl compound represented by the general formula () thus obtained are illustrated below.

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[Table] The photoreceptor of the present invention contains one or more styryl compounds as described above in the photosensitive layer. It can be used as shown in FIG. The photoreceptor shown in FIG. 1 has a photosensitive layer 2 comprising a styryl compound, a sensitizing dye, and a binder (binder resin) on a conductive support 1. The photoreceptor shown in FIG.
The styryl compound here acts as a photoconductive substance, and the generation and transfer of charge carriers necessary for light attenuation take place via the styryl compound. However, styryl compounds have almost no absorption in the visible region of light, so in order to form images with visible light, it is necessary to sensitize them by adding a sensitizing dye that absorbs in the visible region. be. The photosensitive member shown in FIG. 2 has a photosensitive layer 2' provided on a conductive support 1, in which a charge generating substance 3 is dispersed in a charge transporting medium 4 made of a styryl compound and a binder. The styryl compound here forms a charge transport medium together with the binder (or binder and plasticizer), while the charge generating substance 3
(a charge generating substance such as an inorganic or organic pigment) generates charge carriers. In this case, the charge transport medium 4 is mainly responsible for receiving charge carriers generated by the charge generating substance 3 and transporting them. The basic condition for this photoreceptor is that the absorption wavelength regions of the charge generating substance and the styryl compound do not overlap with each other, mainly in the visible region. In order to efficiently generate charge carriers in the charge generation material 3, it is necessary to
This is because it is necessary to transmit light. The styryl compound represented by the general formula () has almost no absorption in the visible region, generally absorbs light in the visible region, and works particularly effectively as a charge transport material when combined with a charge generating material 3 that generates charge carriers. This is its characteristic. The photoreceptor shown in FIG. 3 has a photosensitive layer 2'' consisting of a laminated layer of a charge generation layer 5 mainly composed of a charge generation substance 3 and a charge transport layer 4 containing a styryl compound on a conductive support 1. In this photoreceptor, light transmitted through the charge transport layer 4 reaches the charge generation layer 5, and charge carriers are generated in that region, while the charge transport layer 4 receives injection of charge carriers. The generation of charge carriers necessary for optical attenuation is performed by a charge generation substance 3, and the transport of charge carriers is performed by a charge transport layer 4 (mainly a styryl compound acts). The mechanism is the same as the explanation given for the photoreceptor shown in Figure 2. To actually produce the photoreceptor of the present invention, in the case of the photoreceptor shown in Figure 1, styryl is added to a solution containing a binder. The photosensitive layer 2 may be formed by dissolving one or more compounds and adding a sensitizing dye to the solution, coating this on the conductive support 1 and drying it. The thickness of 2 is 3 to 50 μm, preferably 5 to 50 μm.
20 μm is appropriate. The amount of the styryl compound in the photosensitive layer 2 is 30 to 70% by weight, preferably about 50% by weight, and the amount of the sensitizing dye in the photosensitive layer 2 is 0.1 to 5% by weight, preferably 0.5 to 3% by weight. %. As a sensitizing agent, Brilliant Green,
Victoria Blue B, Methyl Violet, Crystal Violet, Ashit Violet 6B
triarylmethane dyes such as Rhodamine B, Rhodamine 60, Rhodamine G Extra, Eosin S, Erythrosine, Rose Bengal, xanthene dyes such as fluorescein, thiazine dyes such as methylene blue, cyanine dyes such as cyanine, 2,6-diphenylene -4-(N,N-dimethylaminophenyl)thiapyrylium perchlorate, benzopyrylium salt (Special Publication No. 48-25658
Examples include pyrylium dyes such as (described in Japanese Patent No. Note that these sensitizing agents may be used alone or in combination of two or more. In addition, in order to produce the photoreceptor shown in FIG.
The photosensitive layer 2' may be formed by dispersing fine particles of the charge generating substance 3 in a solution containing one or more styryl compounds and a binder, and applying and drying this onto the conductive support 1. . The thickness of the photosensitive layer 2' is 3 to 50 μm, preferably 5 μm.
~20 μm is appropriate. The amount of the styryl compound in the photosensitive layer 2' is 10 to 95% by weight, preferably 30 to 95% by weight.
90% by weight, and the amount of the charge generating substance 3 in the photosensitive layer 2' is 0.1 to 50% by weight, preferably 1 to 50% by weight.
It is 20% by weight. Examples of the charge generating substance 3 include inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, cadmium-selenium sulfide, and α-silicon; examples of organic pigments include CI Pigment Blue 25 (Color Index C 21180);
C.I. Pigment Red 41 (CI 21200), C.I. Acid Red 52 (CI 45100), C.I. Basic Cred. 3 (CI 45210), azo pigment having a carbazole skeleton (described in JP-A-53-94033), Azo pigments having a distylbenzene skeleton (described in JP-A-53-133445), azo pigments having a triphenylamine skeleton (JP-A-53-132347)
Azo pigments having a dibenzothiophene skeleton (described in JP-A-54-21728), azo pigments having an oxadiazole skeleton (described in JP-A-54-21728),
12742), azo pigments having a fluorenone skeleton (described in JP-A-54-22834), azo pigments having a bisstilbene skeleton (described in JP-A-54-22834),
17733), azo pigments having a distyryloxadiazole skeleton (described in JP-A No. 54-2129), azo pigments having a distylcarbazole skeleton (described in JP-A-54-14967) Azo pigments such as C.I. Picment Blue 16
Phthalocyanine pigments such as (CI 74100), indigo pigments such as C.I. Butt Brown 5 (CI 73410), C.I. Butt Dyed (CI 73030), Argo Scarlet B (manufactured by Bayer AG), Indus Thread Scarlet R (manufactured by Bayer AG), Examples include perylene pigments such as (manufactured by Co., Ltd.). Note that these charge generating substances may be used alone or in combination of two or more types. Furthermore, in order to produce the photoreceptor shown in FIG. 3, a charge generating substance is vacuum-deposited on a conductive support 1, or fine particles 3 of a charge generating substance are deposited in a suitable form in which a binder is dissolved if necessary. A dispersion dispersed in a solvent is applied and dried, and if necessary, surface finishing and film thickness adjustment are performed by methods such as bath polishing to form a charge generation layer 5. to 1
The charge transport layer 4 may be formed by applying a solution of a styryl compound or two or more styryl compounds and a binder and drying the solution. The charge generating material used to form the charge generating layer 5 is the same as that used in the description of the photosensitive layer 2'. The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm.
m or less, and the thickness of the charge transport layer 4 is 3 to 50 μm.
A suitable thickness is preferably 5 to 20 μm. When the charge generation layer 5 is of a type in which charge generation substance fine particles 3 are dispersed in a binder, the proportion of the charge generation substance fine particles 3 in the charge generation layer 5 is preferably 10 to 95% by weight. It is about 50 to 90% by weight. Also,
The amount of styryl compound in the charge transport layer 4 is 10
~95% by weight, preferably 30-90% by weight. In the production of any of these photoreceptors, a metal plate or foil made of aluminum or the like, a plastic film deposited with a metal such as aluminum, or paper treated with electrical conductivity is used as the conductive support 1. As the binder, condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide are used. , any insulating and adhesive resin can be used. A plasticizer is added to the binder if necessary, but
Such plasticizers include halogenated paraffins,
Examples include polychlorinated biphenyl, dimethylnaphthalene, and dibutyl phthalate. Furthermore, the photoreceptor obtained in the above manner has
An adhesive layer or barrier layer can be provided between the conductive support and the photosensitive layer, if necessary. Materials used for these layers include polyamide, nitrocellulose, aluminum oxide, etc., and the film thickness is preferably 1 μm or less. To make a copy using the photoreceptor of the present invention, the photoreceptor surface is charged and exposed, then developed and, if necessary, transferred to paper or the like. The photoreceptor of the present invention has excellent advantages such as high sensitivity and flexibility. Examples are shown below. In the following examples, all parts are by weight. Example 1 76 parts of Diane Blue (CI Pigment Blue 25, CI 21180) as a charge generating substance, 1260 parts of a 2% tetrahydrofuran solution of polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) and 3700 parts of tetrahydrofuran were ground in a ball mill. The resulting dispersion was applied using a doctor blade onto the aluminum surface of a conductive support made of a polyester base coated with aluminum vapor, and air-dried to form a charge generation layer with a thickness of about 1 μm. On the other hand, 2 parts of N0.28 styryl compound and polycarbonate resin (Panlite) were used as charge transport materials.
After mixing and dissolving 2 parts of K1300 (manufactured by Teijin Ltd.) and 16 parts of tetrahydrofuran to form a solution, this was applied onto the charge generation layer using a doctor blade, heated to 80°C for 2 minutes, and then heated to 105°C. This was dried for 5 minutes to form a charge transport layer with a thickness of about 20 μm, thereby producing photoreceptor No. 1. Examples 2 to 27 Photoreceptors Nos. 2 to 27 were prepared in exactly the same manner as in Example 1, except that the charge generating substance and the charge transporting substance (styryl compound) were replaced with those shown in Table 1.

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[Table] Example 28 On an aluminum plate having a thickness of about 300 μm, selenium was vacuum-deposited to a thickness of about 1 μm to form a charge generation layer. Next, 2 parts of styryl compound No. 28, 3 parts of polyester resin (Polyester Adhesive 49000 manufactured by DuPont) and tetrahydrofuran.
Mix and dissolve 45 parts to create a charge transport layer forming liquid, apply this onto the charge generation layer (selenium vapor deposited layer) using a doctor blade, air dry, and then dry under reduced pressure to form a thick layer. A charge transport layer having a thickness of about 10 μm was formed to obtain photoreceptor No. 28 of the present invention. Example 29 Perylene pigment instead of selenium A charge generation layer (however, the thickness is about 0.3 μm) was formed using a styryl compound No. 29 instead of No. 28.
Photoreceptor No. 29 was prepared in the same manner as in Example 28 except that the photoreceptor No. 29 was used. Example 30 A mixture of 1 part of Diane Blue (same as that used in Example 1) and 158 parts of tetrahydrofuran was ground and mixed in a ball mill, and then
12 parts of styryl compound No. 28, polyester resin (Polyester Adhesive 49000 manufactured by DuPont)
The photosensitive layer forming solution obtained by adding 18 parts and further mixing was applied onto an aluminum-deposited polyester film using a doctor blade, and dried at 100°C for 30 minutes to form a photosensitive layer with a thickness of about 16 μm. Thus, photoreceptor No. 30 of the present invention was prepared. Regarding photoreceptors No. 1 to 30 thus made,
Using a commercially available electrostatic copying paper tester (SP 428 model manufactured by KK Kawaguchi Denki Seisakusho), conduct a corona discharge of -6KV or +6KV for 20 seconds to charge it, then leave it in a dark place for 20 seconds and measure the surface potential at that time. Measure Vpo (volts), then irradiate the photoreceptor surface with tungsten lamp light so that the illumination intensity is 4.5 lux, find the time (seconds) until the surface potential becomes 1/2 of Vpo, and calculate the exposure amount E1 /2 (lux seconds) was calculated.
The results are shown in Table-2. In addition, each of the above-mentioned photoreceptors is charged using a commercially available electrophotographic copying machine, and then light is irradiated through the original image to form an electrostatic latent image, which is developed using a dry developer. When the resulting image (toner image) was electrostatically transferred onto plain paper and fixed, a clear transferred image was obtained. A similarly clear transferred image was obtained when a wet developer was used as the developer.

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[Table] Effects The photoreceptor of the present invention not only has excellent photosensitive properties, but also has high strength against thermal and mechanical impact, and can be manufactured at low cost.

[Brief explanation of drawings]

1, 2, and 3 are cross-sectional views enlarged in the thickness direction of an electrophotographic photoreceptor according to the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support, 2, 2', 2''... Photosensitive layer, 3... Charge generating substance, 4... Charge transporting medium or charge transporting layer, 5... Charge generating layer.

Claims (1)

[Scope of Claims] 1. A photoreceptor for electrophotography, comprising a photosensitive layer containing as an active ingredient at least one styryl compound represented by the following general formula () on a conductive support. (In the formula, R ¹ represents an alkyl group containing a substituted alkyl group or an aryl group containing a substituted aryl group,
R ² represents a hydrogen atom, an alkyl group including a substituted alkyl group, or an aryl group including a substituted aryl group, and Ar represents an aryl group including a substituted aryl group. )