JP2700231B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member in which a specific compound is contained in a photosensitive layer.

(Prior art)

Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc sulfide have been used as photoconductive materials for photoconductors used in electrophotography. Here, the term "electrophotographic method" generally means that a photoconductive photoreceptor is first charged in a dark place, for example, by corona discharge, and then subjected to image exposure to selectively dissipate the charge of only the exposed portion. An electrostatic latent image is obtained, and the latent image portion is developed and visualized with fine particles (toner) composed of a coloring material such as a dye or a pigment and a binder such as a polymer substance to form an image. This is one of the image forming methods used.

The basic characteristics required of the photoreceptor in such an electrophotographic method include (1) being able to be charged to an appropriate potential in a dark place, (2) being less liable to charge in a dark place, and (3) Charges can be quickly dissipated by light irradiation.

By the way, each of the above-mentioned inorganic substances has many advantages and also has various disadvantages. For example, selenium, which is widely used at present, satisfies the above conditions (1) to (3), but the production conditions are difficult, the production cost is high, there is no flexibility, and the selenium is processed into a belt shape. It also has drawbacks in that it is difficult to handle, and is sensitive to heat and mechanical shocks, and requires careful handling. Cadmium sulfide and zinc oxide are used as photoreceptors by dispersing them in a resin as a binder.However, due to mechanical defects such as smoothness, hardness, tensile strength, and abrasion resistance, they are repeatedly used as they are. Can not be used.

In recent years, electrophotographic photoreceptors using various organic substances have been proposed to eliminate the disadvantages of these inorganic substances, and some of them have been put to practical use. For example, poly-N-vinylcarbazole and 2,4,7-trinitrofluorene-9-
Photoreceptor (described in U.S. Pat. No. 3,484,237), a photoreceptor obtained by sensitizing porin-N-vinylcarbazole with a pyrylium salt dye (described in JP-B-48-25658), organic Photoreceptors containing pigment as a main component
-37543), a photoreceptor having a eutectic complex comprising a dye and a resin as a main component (described in JP-A-47-10735), and a photoreceptor sensitized with a triphenylamine compound (U.S. Pat. No. 3,180,730), and a photoreceptor using poly-N-vinylcarbazole and an amine derivative as a charge transporting material (JP-A-58-1155). Although these photoreceptors have excellent properties and are considered to be of high practical value, in electrophotography, considering various requirements for photoreceptors, these requirements are still insufficient. In fact, it is not possible to obtain anything satisfying the above conditions.

〔Purpose〕

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photoreceptor capable of solving the above-mentioned various disadvantages of the conventional photoreceptor and sufficiently satisfying the conditions required in electrophotography. It is a further object of the present invention to provide an electrophotographic photoreceptor which is easy to manufacture, relatively inexpensive, and has excellent durability.

〔Constitution〕

According to the present invention, the following general formula (I) is provided on a conductive support.
A photosensitive layer containing at least one of the biphenyl compounds represented by the formula (1) as an active ingredient.

(Wherein, R ₁ and R ₂ are a substituted or unsubstituted alkyl group,
Represents a substituted or unsubstituted aryl group, and at least one of R ₁ and R ₂ represents a substituted or unsubstituted aryl group. In the invention, the above general formula (I) to be contained in the photosensitive layer
The biphenyl compound represented by the general formula (II) 2,4-diiodo-5-methoxybiphenyl represented by the general formula (III) (Wherein R ₁ and R ₂ are the same as defined above), and are prepared by reacting with an amine represented by (III). In addition, acetylamines represented by the general formula (IV) R ₁ —NHCOCH ₃ (IV) (wherein R ₁ represents a substituted or unsubstituted aryl group) are represented by the general formula (V). After obtaining the diacetyl compound (Wherein, R ₁ represents a substituted or unsubstituted aryl group), and then a halide represented by the general formula (VI) R ₂ —X (VI) (where R ₂ is the same as defined above) , X represents a halogen atom) to obtain a biphenyl compound represented by the general formula (I). (Wherein R ₁ and R ₂ are the same as defined above).

The biphenyl compound represented by the general formula (I) thus obtained is exemplified below.

In the photoreceptor of the present invention, one or more of the above biphenyl compounds are used in the photosensitive layer 2 (2 ′, 2 ″, 2 or 2).
'), But can be used as shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4 or FIG. 5 depending on the application of these biphenyl compounds.

The photoreceptor in FIG. 1 has a conductive support 1 on which a photosensitive layer 2 made of a biphenyl compound, a sensitizing dye and a binder (binder resin) is provided. The biphenyl compound here acts as a photoconductive substance, and the generation and transfer of charge carriers required for light decay are performed via the biphenyl compound. However, since the biphenyl compound has little absorption in the visible region of light, it is necessary to sensitize by adding a sensitizing dye having absorption in the visible region for the purpose of forming an image with visible light. .

The photosensitive member shown in FIG. 2 has a photosensitive layer 2 'in which a charge generating substance 3 is dispersed in a charge transporting medium 4 comprising a biphenyl compound and a binder on a conductive support 1. The biphenyl compound here is a binder (or
Together with the binder and the plasticizer) form a charge transport medium, while the charge generating material 3 (a charge generating material such as an inorganic or organic pigment) generates charge carriers. In this case, the charge transport medium 4 is mainly responsible for receiving and transporting charge carriers generated by the charge generating substance 3. In this photoreceptor, the basic condition is that the charge generating substance and the biphenyl compound do not overlap in the absorption wavelength region mainly in the visible region. This is because it is necessary to transmit light to the surface of the charge generating material 3 in order to efficiently generate charge carriers in the charge generating material 3. The biphenyl compound represented by the general formula (I) has almost no absorption in the visible region, and generally absorbs light in the visible region, and is particularly effective as a charge transport material when combined with the charge generation material 3 which generates charge carriers. The feature is that it works.

The photosensitive member shown in FIG. 3 is a photosensitive layer 2 ″ comprising a conductive support 1 and a charge generating layer 5 mainly composed of a charge generating substance 3 and a charge transport layer 4 containing a biphenyl compound.
Is provided. In this photoreceptor, the light transmitted through the charge transport layer 4 reaches the charge generation layer 5 and charge carriers are generated in that region. On the other hand, the charge transport layer 4 receives injection of the charge carriers and transports them. The charge carriers required for light attenuation are generated by the charge generating substance 3, and the charge carriers are transported by the charge transport layer 4 (mainly the biphenyl compound works). Such a mechanism is the same as that described for the photosensitive member shown in FIG.

The photoreceptor in FIG. 4 is obtained by reversing the stacking order of the charge generation layer 5 and the charge transport layer 4 containing the biphenyl compound in FIG. 3, and the mechanism of generation and transport of the charge carriers is as described above. You can do the same. In this case, a protective layer 6 can be provided on the charge generation layer 5 as shown in FIG. 5 in consideration of mechanical strength.

To actually prepare the photoreceptor of the present invention, if the photoreceptor shown in FIG. 1 is used, one or two or more biphenyl compounds are dissolved in a solution in which a binder is dissolved, and further a sensitizing dye is added thereto. , A liquid to which the photosensitive layer 2 may be formed by coating the liquid on the conductive support 1 and drying the liquid.

The thickness of the photosensitive layer is 3 to 50 µm, preferably 5 to 20 µm. The amount of the biphenyl compound in the photosensitive layer 2 is
The amount 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. Examples of sensitizing charges include brilliant green, Victoria Blue B, methyl violet, crystal violet, triarylmethane dyes such as Acid Violet 6B, rhodamine B,
Rhodamine 6G, Rhodamine G Extra, Eosin S,
Xanthene dyes such as erythrosine, rose bengal, and fluorescein; thiazine dyes such as methylene blue; cyanine dyes such as cyanine; 2,6-diphenyl-4- (N, N-dimethylaminophenyl) thiapyrylium perchlorate; Pyrylium salt (JP-B-48-25
No. 658) and pyrylium dyes. It should be noted that even if these sensitizing charges are used alone,
More than one species may be used in combination.

In addition, in order to produce the photoreceptor shown in FIG. 2, fine particles of the charge generating substance 3 are dispersed in a solution in which one or more biphenyl compounds and a binder are dissolved, and this is used as a conductive support. 1 and dried to form a photosensitive layer 2 '.

The thickness of the photosensitive layer 2 'is 3 to 50 .mu.m, preferably 5 to 20 .mu.m.
m is appropriate. The amount of the biphenyl compound in the photosensitive layer 2 'is 10 to 95% by weight, preferably 30 to 90% by weight,
The amount of the charge generating substance 3 occupying the photosensitive layer 2 'is 0.1 to 5%.
0% by weight, preferably 1 to 20% by weight. Examples of the charge generating substance 3 include inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, cadmium sulphide-selenium, and α-silicon. Examples of the organic pigments include CI Pigment Blue 25 (color index CI 21180) and CI Pigment Red 41. (CI 21200), CI Acid Red 52 (CI 45100), CI Basic Red 3 (CI
45210), an azo pigment having a carbazole skeleton (JP-A
53-95033), azo pigments having a distyrylbenzene skeleton (JP-A-53-133445), azo pigments having a triphenylamine skeleton (described in JP-A-53-132347), dibenzo Azo pigments having a thiophene skeleton (described in JP-A-54-21728), azo pigments having an oxadiazole skeleton (described in JP-A-54-12742), and azo pigments having a fluorenone skeleton (described in JP-A-54-12742) 54−
No. 22834), an azo pigment having a bisstilbene skeleton (described in JP-A-54-17733), and an azo pigment having a distyryloxadiazole skeleton (described in JP-A-54-21)
Azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-14967), such as C.I. Pigment Blue 16 (CI 7410).
Phthalocyanine-based pigments such as C.I.Hat Brown 5 (CI 73410), C.I.
Indigo pigments such as 3030), Argo Scarlet B
(Manufactured by Bayer AG) and perylene pigments such as Indance Scarlet R (manufactured by Bayer AG).
These charge generating substances may be used alone or in combination of two or more.

Further, to prepare the photoreceptor shown in FIG. 3, a charge generating substance is vacuum-deposited on the conductive support 1 or more, or
If necessary, a dispersion liquid in which the fine particles 3 of the charge generating substance are dispersed in a suitable solvent in which a binder is dissolved is applied and dried, and if necessary, the surface is finished by a method such as buffing, and the film thickness is adjusted. To form the charge generation layer 5,
A solution in which one or two or more biphenyl compounds and a binder are dissolved is applied thereon and dried to form the charge transport layer 4. Here, the charge generation material used for forming the charge generation layer 5 is the same as that described in the description of the photosensitive layer 2 '.

The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm.
The thickness of the charge transport layer 4 is 3 to 50 μm, preferably 5 to 20 μm. In the type in which the charge generation layer 5 has the fine particles 3 of the charge generation layer material dispersed in a binder, the ratio of the fine particles 3 of the charge generation material to the charge generation layer 5 is preferably 10 to 95% by weight. Is about 50 to 90% by weight. The amount of the compound in the charge transport layer 4 is 10%.
9595% by weight, preferably 30-90% by weight. In order to produce the photoreceptor shown in FIG. 4, a solution in which a biphenyl compound and a binder are dissolved is applied on the conductive support 1 and dried to form the charge transport layer 4. The charge generation layer 5 may be formed by applying a dispersion of fine particles of the charge generation layer material in a solvent in which a binder is dissolved, if necessary, by a method such as spray coating and drying. The amount ratio of the electric field generating layer or the charge transport layer is the same as that described in FIG. By forming a protective layer 6 on the charge generating layer 5 of the photoreceptor thus obtained by spraying an appropriate resin solution or the like, the photoreceptor shown in FIG. 5 can be prepared. As the resin used here, a binder described later can be used.

In the production of any of these photoconductors, a metal plate or metal foil of aluminum or the like, a plastic film on which a metal such as aluminum is vapor-deposited, or a paper subjected to a conductive treatment is used for the conductive support 1. Examples of the binder include 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. All insulating and adhesive resins can be used. If necessary, a plasticizer is added to the binder. Examples of such a plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutylphthalate.

Further, the photosensitive member obtained as described above may be provided with an adhesive layer or a barrier layer between the conductive support and the photosensitive layer, if necessary. Materials used for these layers include polyamide, nitrocellulose, and aluminum oxide, and the film thickness is preferably 1 μm or less.

To make a copy using the photoreceptor of the present invention, the photosensitive surface is charged, exposed, then developed, if necessary,
Transfer to paper etc. The photoconductor of the present invention has high sensitivity,
In addition, it has excellent advantages such as high flexibility.

〔Example〕

Hereinafter, the present invention will be described with reference to examples. In the following examples, all parts are parts by weight.

[Synthesis of Compound of General Formula (I)]

(Synthesis Example of Compound No. 6) 4.36 g of 2,4-diiodo-5-methoxybiphenyl (0.01
0 mol), 4.34 g (0.022 mol) of p-ditolylamine, 3.65 g (0.026 mol) of potassium carbonate, and 0.10 g of copper powder were placed in 50 ml of nitrobenzene, and heated and refluxed for 9 hours under a nitrogen stream.
After cooling to room temperature, the insoluble portion was removed by filtration together with Celite, and nitrobenzene was distilled off under reduced pressure. The resulting brown oily product was subjected to column treatment (first carrier; silica gel, eluent; toluene; second carrier; silica gel, eluent; toluene / n-hexane = 1/1), followed by mixing of toluene-n-hexane. Recrystallization from the solvent gave 1.44 g of 2,4-bis (N, N-di-p-tolyl-amino) -5-methoxybiphenyl (compound No. 6) as colorless plate crystals. 189.5-190.5 ° C. Elemental analysis values (%) were as follows as C ₄₁ H ₃₈ N ₂ O.

CH N measured 85.72 6.54 4.68 calculated 85.66 6.68 4.87 The infrared absorption spectrum (KBr tablet method) of this compound is shown in FIG.

Example 1 76 parts of Diane Blue (C.I. Pigment Blue 25, CI 21180), 1260 parts of a 2% tetrahydrofuran solution of a polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) and 3,700 parts of tetrahydrofuran were ground in a ball mill as charge generating substances. After mixing, the obtained dispersion was applied on an aluminum surface of a conductive support made of a polyester base on which aluminum was deposited by using a doctor blade, and was naturally dried to form a charge generating layer having a thickness of about 1 μm.

On the other hand, as a charge transport material, 2 parts of a biphenyl compound of No. 6 and a polycarbonate resin (Panlite K1300,
2 parts and 16 parts of tetrahydrofuran were mixed and dissolved to form a solution, which was then applied to the charge generating layer using a doctor blade, and then applied at 80 ° C. for 2 minutes.
After drying at 120 ° C. for 5 minutes to form a charge transport layer having a thickness of about 20 μm, photoconductor No. 1 was prepared.

Examples 2 to 15 Photoconductors were made in exactly the same manner as in Example 1 except that the charge generating substance and the charge transporting substance were changed to those shown in Table 1.
Nos. 2 to 15 were created.

Example 16 The following perylene pigment was vacuum-deposited to a thickness of about 1 μm on an aluminum plate having a thickness of 300 μm to form a charge generation layer. Next, 2 parts of No. 6 biphenyl compound and polyester resin (Polyester Adhesive 49000 manufactured by DuPont)
3 parts and 45 parts of tetrahydrofuran are mixed and dissolved to form a charge transport layer forming solution, which is applied to the charge generation layer using a doctor blade, air-dried, and then dried under reduced pressure to obtain a thickness. By forming a charge transport layer of about 10 μm, photoconductor No. 16 of the present invention was obtained.

Example 17 A mixture of 1 part of Diane Blue (same as that used in Example 1) and 158 parts of tetrahydrofuran was pulverized and mixed in a ball mill, and then mixed with 12 parts of a biphenyl compound of No. 5 and a polyester resin ( 18 parts of DuPont polyester adhesive 49000) was added, and the photosensitive layer forming liquid obtained by further mixing was applied onto an aluminum-evaporated polyester film using a doctor blade, and the solution was heated at 100 ° C for 30 minutes.
After drying for about 1 minute to form a photosensitive layer having a thickness of about 16 μm, Photoconductor No. 17 of the present invention was prepared.

Example 18 A charge transport layer coating solution used in Example 8 was blade-coated in the same manner as in Example 1 on an aluminum-evaporated polyester film substrate, and then dried to a thickness of about 20 μm.
Was formed. Bisazo pigment (P-2) 13.5
Parts, 5.4 parts of polyvinyl butyral (trade name: XYHL Union Carbide Plastics Co., Ltd.), 680 parts of THF and 1020 parts of ethyl cellosolve were pulverized and mixed in a ball mill, and 1700 parts of ethyl cellosolve were added and mixed with stirring to form a coating for the charge generation layer. A working liquid was obtained. This coating solution was spray-coated on the charge transport layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 0.2 μm. Further, a methanol / n-butanol solution of a polyamide resin (trade name: CM-8000, manufactured by Toray) is spray-coated on the charge generation layer and dried at 120 ° C. for 30 minutes to form a protective layer having a thickness of about 0.5 μm. Photoreceptor N
o.18 was created.

The photoreceptors Nos. 1 to 18 thus produced were charged by performing a −6 KV or +6 KV corona discharge for 20 seconds using a commercially available electrostatic copying paper tester (SP428, manufactured by KK Kawaguchi Electric Works). Leave for 20 seconds in a dark place, then the surface potential Vp
o (volt), then illuminate the surface of the photoreceptor with a tungsten lamp so that the illuminance is 4.5 lux, and calculate the time (second) until the surface potential becomes 1/2 of Vpo. E1 / 2 (looks-seconds) was calculated. Table 2 shows the results.

Also, after charging each of the above photoreceptors using a commercially available electrophotographic copying machine, irradiating light through the original drawing to form an electrostatic latent image, and developing using a dry developer, the obtained The transferred image (toner image) was electrostatically transferred onto plain paper and fixed, and a clear transferred image was obtained. Similarly, when a wet type developer was used as the developer, a clear transfer image was obtained.

[Effects] The photoreceptor of the present invention is not only excellent in photosensitive characteristics but also has high strength against heat and mechanical shock and can be manufactured at low cost.

[Brief description of the drawings]

1 to 5 are cross-sectional views of the electrophotographic photosensitive member according to the present invention, which are enlarged in the thickness direction, and FIG. 6 is an infrared absorption spectrum of the biphenyl compound used in the present invention. DESCRIPTION OF SYMBOLS 1 ... Conductive support 2,2 ', 2 ", 2,2' ... Photosensitive layer 3 ... Charge generating substance 4 ... Charge transporting medium or charge transport layer 5 ... Charge generating layer 6 ... Protective layer

Claims (1)

(57) [Claims] An electrophotographic photosensitive member comprising a conductive support and a photosensitive layer containing at least one of the biphenyl compounds represented by the following general formula (I) as an active ingredient. (Wherein, R ₁ and R ₂ are a substituted or unsubstituted alkyl group,
Represents a substituted or unsubstituted aryl group, and at least one of R ₁ and R ₂ represents a substituted or unsubstituted aryl group. )