JPH05289383A - Flexible electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body having excellent surface smoothness by making its curl-protective layer contain a styrene-butadiene copolymer of a prescribed value or below in the elongation of resin. CONSTITUTION:In a flexible electrophotographic sensitive body having at least an electroconductive layer and a photoconductive layer on a flexible film like supporting body and having the curl protective layer on the rear surface of the supporting body, the styrene-butadiene copolymer having <=235% elongation of resin is contained in the curl protective layer. In this case, the elongation of resin means a value determined by a testing method established by JIS-K6301 or JIS-6871 or ASTM-D638. The molecular structure of the styrene-butadiene copolymer is a random or block copolymer and it is also effective to use the random copolymer in combination with the block copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having a photoconductive layer formed of a photoconductive material, and more specifically, it is provided on the side opposite to the side provided with the photoconductive layer. The present invention relates to the improvement of the curl prevention layer on the back surface of the support.

[0002]

2. Description of the Related Art Conventionally, an inorganic photoconductive substance such as selenium, cadmium sulfide or zinc oxide has been widely used for a photosensitive layer of an electrophotographic photoreceptor. A photoreceptor using such an inorganic photoconductor has various advantages as well as various disadvantages, and in the case of selenium, selenium has low productivity and production due to vacuum deposition. There are problems that the manufacturing cost is high due to difficult conditions, wear of raw materials, and the like, and the selenium vapor deposition film itself is extremely weak against heat and mechanical shock, and is extremely likely to crystallize depending on environmental conditions. Cadmium sulfide is vulnerable to humidity and has a problem of pollution except for the photoreceptor coated with an insulating layer. In the case of zinc oxide, since it is sensitized with a dye having a low fastness such as rose bengal, there are problems such as deterioration of electrical current due to corona charging and photobleaching. Further, since the zinc oxide particles are a resin dispersion system, there are problems in surface smoothness, hardness, abrasion resistance and the like of the photosensitive layer.

On the other hand, an organic photoconductive substance has a more flexible photosensitive layer than an inorganic photoconductive substance, is easy to manufacture, and is cheaper to obtain a photoconductor having stable electrophotographic characteristics. There are many advantages and many proposals have been made in recent years.

The types of photoreceptors using organic light-guiding substances include (1) those in which a charge transfer complex is formed by combining an electron-donating compound and an electron-accepting compound (eg, US Pat. No. 3,484,237), (2) Sensitized by adding a dye to an organic photoconductor (eg, JP-B-48-25658)
(3) a pigment dispersed in a positive hole or electron active matrix (eg, Eikai 47-30328, JP 47-18545), and (4) functions as a charge generation layer and a charge transport layer. Those dispersed (eg, JP-A-49-10553)
No. 7), (5) three-component eutectic complex consisting of dye and resin (eg, JP-A-47-10785), (6) organic pigment or inorganic charge in the charge transfer complex. Addition of a generating material (eg, JP-A-49-916)
No. 48).

Among them, the photoconductor of the type (4) (function separation type) has been put into practical use because it is possible to select various materials in combination with high sensitivity and high function. Here, the charge generation layer is usually prepared by dispersing a charge generation substance such as an azo pigment, a phthalocyanine pigment, an indigo pigment, and a perylene pigment in a resin binder such as polyester, polycarbonate, polyvinyl butyral, and acrylic resin. It is formed by coating on a support. The charge-transporting layer is usually a triphenylamine-based compound, a hydrazone-based compound, an α-phenylstilbene-based compound, a pyrazoline-based compound, or another charge-transporting substance such as polyester, polysulfone, polycarbonate, polymethacrylic acid ester,
Dissolve in an organic solvent together with a resin such as polystyrene,
It is formed by applying and drying this. At this time, the stacking order of the charge generation layer and the charge transport layer may be arbitrarily determined as needed. Further, an undercoat layer (intermediate layer) and an overcoat layer can be combined if necessary.

Hereinafter, an electrophotographic photosensitive member mainly made of an organic material is abbreviated as OPC. If the base of the OPC is a flexible film such as a polyethylene terephthalate film, the endless belt shape of the photosensitive member increases the degree of freedom in mechanical design layout. Further, if the endless belt is partially flat in the copying machine, high-speed copying becomes possible by using flash exposure. Furthermore, if the substrate including the electrodes is made light-transmissive, it is possible to efficiently remove light from the back surface. Belt-shaped OPC is lightweight,
It has excellent mass productivity and can be easily discarded after use. For this reason, the OPC belt is currently a typical electrophotographic photosensitive member, and its improvement is of great practical value.

It is recognized that one of the problems of the above OPC belt is that it easily curls. The OPC belt curls,
When the surface of the photoconductive layer loses its flatness, the distance between the photoconductive layer and the belt rotating device such as a charging device and a developing device becomes uneven in the copying machine. This is due to the uneven charging potential during the charging process,
This may cause uneven focus during the exposure process and scumming during the development process. When the OPC belt unit to which the OPC belt is attached is attached to or detached from the main body of the copying machine,
If the edge of the PC belt is curled up due to curls,
In some cases, the OPC belt may be broken due to contact with the belt rotation device. This phenomenon significantly shortens the life of the OPC belt.

As a means for removing the curl of the OPC belt, it is generally known to provide a curl prevention layer. Specifically, there is an anti-curl layer containing a reaction product of a film-forming binder, crystal particles and a bifunctional chemical binder (eg, JP-A-62-100764). However, these anti-curl layers peel off from the support after long-term use in the copying machine, leaving many problems in the adhesive force, which makes it difficult to attach the unit including the photoconductor to the copying machine body and handle it. It has a drawback that it causes trouble.

[0009]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art, does not peel off the curl layer from the support even after long-term use, and has excellent surface smoothness. It is an object of the present invention to provide a flexible electrophotographic photosensitive member that is easily attached to the main body of the machine and has good hand linking properties.

[0010]

According to the present invention, a flexible electrophotography having at least a conductive layer and a photoconductive layer on a flexible film-like support and further having a curl prevention layer on the back surface of the support. In the photoconductor, the curl prevention layer has a resin elongation of 235% or less.
Provided is a flexible electrophotographic photoreceptor including a butadiene copolymer resin.

A feature of the present invention is that at least the surface of the support opposite to the photosensitive layer including the photoconductive layer, that is, the back surface of the support,
This is to provide an anti-curl layer containing a styrene-butadiene copolymer resin having a resin elongation of 235% or less. Here, the elongation of the resin means JIS K6301 or
It is a value obtained by the test method established in JIS K6871 or ASTM D638. The molecular structure of the styrene / butadiene copolymer resin is random or
It is a block copolymer, and it is also effective to use a mixture of a random copolymer and a block copolymer.

Generally, the requirements for the anti-curl layer are as follows: first, the degree of expansion or contraction of the photosensitive layer including the photoconductive layer provided on the flexible film support after coating and drying is flexible film support. It is possible to prevent the curl by providing a layer on the back surface of the support, which is different from the above-mentioned one, on the back surface of the support so as to expand or contract as much as the photosensitive layer including the photoconductive layer.

Secondly, it is necessary that the adhesiveness when it is directly provided on the back surface of the support must be at a level that causes no practical problem in the copying machine. Therefore, in general, in order to prevent curling, it is considered that the object can be achieved by using the same binder resin as that used in the photosensitive layer including the photoconductive layer as a component of the curl preventing layer.

However, in practice, the photosensitive layer including the photoconductive layer does not come into direct contact with the support, and is provided on the support with a conductive layer and, in some cases, an undercoat layer (intermediate layer) interposed. Therefore, the binder resin used for the photosensitive layer including the photoconductive layer does not always have the adhesiveness to the support, which is practically problem-free in the copying machine. With respect to this point, the present inventor has made further studies and found that when a styrene / butadiene copolymer resin having a resin elongation of 235% or less, more preferably 3 to 100%, is used as a main component of the curl prevention layer. Found that an electrophotographic photoreceptor satisfying the above-mentioned various requirements can be obtained, and completed the present invention.

The styrene / butadiene copolymer resin used in the present invention has a styrene / butadiene copolymerization ratio of 10:90 to 90:10 and an elongation of 235% or less. It is preferably used. The curl prevention layer is provided by applying the styrene / butadiene copolymer resin to the back surface of the support and drying. The thickness of the anti-curl layer should be determined by the degree of curl of the OPC belt. That is, O with a large curl amount
For a PC belt, the film thickness of the anti-curl layer is inevitably thicker than that for an OPC belt having a small amount.

Further, in the present invention, the procedure for providing the curl prevention layer on the back surface of the support is not particularly limited.
That is, the layer containing the photoconductive layer may be provided on the surface of the support after the anticurl layer is provided, or the anticurl layer may be provided on the back surface of the support after the layer containing the photoconductive layer is provided.

Examples of the flexible support to be used in the present invention include synthetic resin sheets such as polyimide, polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and the like, and especially polyethylene terephthalate (PET) is used. Is preferred.

In the present invention, a conductive layer is provided on one surface of the support, and the conductive layer is aluminum,
A thin metal film of nickel, chromium, titanium, or the like, or an alloy thin film of these metals, such as nichrome, hastelloy, inconel, or stainless is suitable. Furthermore, a metal oxide-based transparent conductive material can also be adopted. It can also be achieved by applying a carbon-based paint.

The photoconductive layer may be a single layer type or a laminated type.
In the case of a laminated type, a combination of a charge generation layer and a charge transport layer, which is widely known as a function separation type, is preferable. The charge generation layer will be described below. The charge generation layer is composed of an organic charge generation material or an organic charge generation material and a binder resin.

This organic charge generating material is, for example, CI Pigment Blue 25 (color index CI 21
180), CI Pigment Red 41 (CI 21
200), CI Acid Red 52 (CI 451
00), CI Basic Red 3 (CI 4521
0), an azo pigment having a carbazole skeleton (JP-A-53-53
-95033), an azo pigment having a distyrylbenzene skeleton (described in JP-A-53-133445), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132347), Azo pigments having a dibenzothiophene skeleton (JP-A-54-21728)
JP-A-54-12834), an azo pigment having an oxadiazole skeleton (described in JP-A-54-12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-22834), and a bisstilbene skeleton. Azo pigments (described in JP-A-54-17733) and azo pigments having a distyryl oxadiazole skeleton (JP-A-54-54).
2129) and azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-14967); for example, phthalocyanine pigments such as CI Pigment Blue 16 (CI 74100); Brown 5 (CI 7341
0), indigo-based pigments such as CI BAT Die (CI 73030); Argol Scarlet B (manufactured by Bayer), Induslen Scarlet R (manufactured by Bayer).
Perylene pigments such as, squaric dye, hexagonal Se
Powder etc. are mentioned.

These charge generating materials are pulverized and dispersed with a solvent such as tetrahydrofuran, cyclohexanone, dioxane or dichloroethane by a method such as a ball mill, an attritor or a sand mill. At this time, for example, polyamide, polyurethane, polyester, epoxy resin,
Resins such as polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide may be added as a binder. The charge generation layer forming liquid thus prepared is applied and dried by a method such as a bead coating method, a nozzle coating method, a blade coating method, a dipping method or a spraying method to form a charge generation layer.

Next, the charge transport layer will be described. The charge transport material is a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, coronene or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, triazole in the main chain or side chain. Compounds having nitrogen-containing cyclic compounds such as, triphenylamine compounds, hydrazone compounds (JP-A-55-467)
60), an α-phenylstilbene compound (JP-A-58)
-198043) and the like are used. These charge transport materials are polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride,
Vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic Resin, silicone resin, epoxy resin,
Melamine resin, urethane resin, phenolic resin, alkyd resin and other vapor or thermosetting resins, together with tetrahydrofuran, cyclolhexanone, dioxane,
Dissolve in a solvent such as dichloroethane to prepare a charge transport layer forming liquid, and use this liquid for bead coating, nozzle coating,
It is applied by a method such as a dipping method or a spray method, and dried to form a charge transport. A suitable film thickness is 5 to 50 μm, more preferably 15 to 35 μm.

If desired, an undercoat layer (intermediate layer) can be provided between the conductive layer and the photoconductive layer. In that case, a material selected from the resins listed as the binder of the charge generation layer can be used, and further, a white pigment such as titanium oxide or an alkali metal salt of sulfonic acid or sulfonic acid,
An anionic conductive polymer such as an ammonium salt may be added. At this time, it is preferable to select a material that does not dissolve in the solvent used for the forming liquid of the layer laminated on the undercoat layer. Further, an overcoat layer may be provided on the uppermost layer if necessary.

[0024]

The present invention is explained in more detail by the following examples, which are merely illustrative and the invention is not limited to the materials, conditions, processes, parameters etc. cited therein. .. Also, all parts and percentages are by weight unless otherwise specified.

Example 1 A styrene / butadiene block copolymer resin (Alex 85 manufactured by Asahi Kasei Corporation) having a resin elongation of 20% 1000
Parts was dissolved in 9000 parts of tetrahydrofuran to prepare a curl prevention layer forming liquid. This solution was coated on a polyethylene terephthalate film support having a thickness of 100 μm and dried to form a curl prevention layer having a thickness of 20 μm.
Next, aluminum having a thickness of about 1000 Å was provided on the surface of the support opposite to the side on which the anti-curl layer was provided by a vacuum deposition method to form a conductive layer. Next, 240 parts of alcohol-soluble copolymer nylon (CM-8000 Toray Co., Ltd.) was dissolved in 3000 parts of methanol and 300 parts of butanol to prepare a subbing layer forming liquid, which was coated on the above conductive layer by a beat coating method and dried. Then, an undercoat layer having a film thickness of about 1 μm was provided. Then, the compound (I) 1 having the following structural formula
3.5 parts, polyvinyl butyral resin (XYHL UC
5.4 parts and tetravidrofuran 360 parts are kneaded and dispersed in a ball mill for 72 hours, and then 211 parts of tetrahydrofuran and 356 parts of ethylene glycol monoethyl ether are further added and kneaded and dispersed for 1 hour, and then 110 parts of tetrahydrofuran, A charge generation layer forming liquid was prepared by diluting with 664 parts of ethylene glycol monoethyl ether.

[Chemical 1] This solution was applied onto the undercoat layer by a bead coating method and dried to form a charge generation layer having a thickness of about 0.5 μm. Further, 935 parts of a compound (II) having the following structural formula and 1039 parts of a polycarbonate resin (manufactured by Panlite C-1400 Teijin Limited) are dissolved in 7900 parts of tetrahydrofuran to give a silicone oil (KF-50 manufactured by Shin-Etsu Chemical Co., Ltd.) (1%). 2 parts of tetrahydrofuran solution) was added to prepare a charge transport layer forming liquid.

[Chemical 2] This liquid was applied onto the charge generating layer by a nozzle coating method and dried to provide a charge transporting layer having a thickness of about 20 μm to prepare an electrophotographic photoreceptor of the present invention.

Example 2 In Example 1, the elongation of the styrene / butadiene block copolymer resin, which is the curl preventing layer forming liquid component, was 8%.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the film thickness was changed to 21 μm instead of 4% of styrene / butadiene block copolymer resin (Clearene 730L manufactured by Denki Kagaku Kogyo KK).

Example 3 In Example 1, the elongation of the resin was 1 when the styrene / butadiene block copolymer resin, which is a component for forming the curl preventing layer, was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 5% of styrene / butadiene block copolymer resin (Clearene 530L manufactured by Denki Kagaku Kogyo Co., Ltd.) was used and the thickness thereof was changed to 25 μm.

Example 4 In Example 1, the styrene / butadiene block copolymer resin, which is a component for forming the curl preventing layer, was added to the resin composition to give an elongation of 3
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the film thickness was changed to 18 μm instead of 4% styrene / butadiene block copolymer resin (Clearene 750L manufactured by Denki Kagaku Kogyo Co., Ltd.).

Example 5 Styrene / butadiene block copolymer resin having a resin elongation of 10% (Denka Styrol TP-produced by Denki Kagaku Kogyo KK)
MI 7450) (1000 parts) was dissolved in toluene (9000 parts) to prepare a curl prevention layer forming liquid. This liquid 1
It was coated on a polyethylene terephthalate support having a thickness of 00 μm and dried to provide a curl prevention layer having a thickness of 20 μm. The conductive layer, undercoat layer, charge generation layer, charge transport layer,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1.

Example 6 In Example 1, the elongation of the resin was 2 when the styrene / butadiene block copolymer resin as the curl preventing layer forming liquid component was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the film thickness was 25 μm instead of 30% styrene / butadiene block copolymer resin (Asaflex 925, manufactured by Asahi Kasei Corporation).

Comparative Example 1 In Example 1, the styrene / butadiene block copolymer resin, which is a component for forming the curl preventing layer, was added to the resin composition to give an elongation of 2%.
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 50% styrene / butadiene block copolymer resin (Asaflex 810 manufactured by Asahi Kasei Corporation) was used.

Comparative Example 2 In Example 1, the styrene / butadiene block copolymer resin, which is a component for forming the curl prevention layer, was added to the resin composition to give an elongation of 8%.
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the styrene / butadiene block copolymer resin (Califlex KX155, manufactured by Shell Chemical Co., Ltd.) was changed to 00%.

Comparative Example 3 In Example 1, the elongation of the resin was 6 when the styrene / butadiene block copolymer resin which is the component for forming the curl preventing layer was used.
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 70% styrene / butadiene block copolymer resin (JSR TR2400 manufactured by Japan Synthetic Rubber Co., Ltd.) was used.

Comparative Example 4 In Example 1, except that the styrene / butadiene block copolymer resin as the curl preventing layer forming liquid component was replaced with a polycarbonate resin (K1300 manufactured by Teijin Chemicals Ltd.) and the film thickness was changed to 13 μm. An electrophotographic photosensitive member was prepared in the same manner as in Example 1.

Comparative Example 5 In Example 1, the styrene / butadiene block copolymer resin as the curl preventing layer forming liquid component was replaced with a polyarylate resin (U-100, manufactured by Unitika Ltd.), and the film thickness was 11
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the thickness was changed to μm.

Comparative Example 6 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the curl prevention layer was omitted. The curl amount and the adhesiveness of the curl prevention layer of the flexible electrophotographic photosensitive members prepared in the above Examples and Comparative Examples were evaluated as follows.

The curl amount was measured by cutting the photosensitive member into a size of 10 × 10 cm, placing it on a surface plate, and measuring it with a height gauge. The adhesiveness is 90 ° peeling test method (cut the photosensitive member into 5 × 10 cm, fix the photosensitive member side to the surface plate with double-sided tape, peel off a part of the short end face of the back coat layer, and use only the spring. The tension was measured while pulling up to 90 ° in the longitudinal direction. The results are shown in Table 1. ◎: Level where there is no practical problem in the copying machine ○: Level where there is almost no problem in the copying machine, but operability is slightly difficult ×: Level that cannot be used in actual use

[Table 1]

[0038]

The electrophotographic photosensitive member of the present invention has a flexible film-like support, at least a conductive layer and a photoconductive layer, and a flexible anti-curl layer on the back surface of the support. In the body, since the anti-curl layer contains a styrene / butadiene copolymer resin having a resin elongation of 235% or less, the anti-curl layer does not peel off from the support even after long-term use, resulting in excellent surface smoothness. Have sex. Therefore, the electrophotographic photosensitive member of the present invention is easy to mount on the main body of the copying machine and has excellent handling property, and its practical value is extremely high.

Claims (1)

[Claims] 1. A flexible film-shaped support,
In a flexible electrophotographic photosensitive member having at least a conductive layer and a photoconductive layer and further having a curl prevention layer on the back surface of the support, the curl prevention layer contains a styrene / butadiene copolymer resin having an elongation of 235% or less. A flexible electrophotographic photosensitive member characterized by the above.