JPH0675413A - Flexible electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] [Purpose] A flexible electrophotography that does not peel off the curl-preventing layer from the support even after long-term use, has excellent surface properties, and is easy to mount on the copying machine and easy to handle. Providing a photoconductor. In a flexible electrophotographic photosensitive member having a curl prevention layer on the back surface of a support, the curl prevention layer contains at least one resin selected from the following resin (A) group and a resin (B). A flexible electrophotographic photosensitive member. Resin (A) Polysulfone resin Polyarylate resin Polycarbonate resin Polyester carbonate resin Resin (B) Styrenic thermoplastic elastomer

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, to the side opposite to the side provided with the photoconductive layer. The present invention relates to an electrophotographic photosensitive member having an improved anti-curl layer provided on the back surface of a support.

[0002]

2. Description of the Related Art Conventionally, a photoconductor using an inorganic photoconductor has been used as an electrophotographic photoconductor. However, these photoconductors have problems in productivity, cost, discardability after use, and the like.
In recent years, photoconductors using organic photoconductors, which have advantages of high productivity, low cost, and no pollution, have been widely used. Among the photoconductors using such organic photoconductors, the endless belt-shaped photoconductors mainly composed of the photoconductive substance, the binder resin, and the flexible support have a high flexibility. The flexibility in layout design is high, and if the endless belt is partly flat in the copier, high-speed copying is possible by using flash exposure. Then, there is an advantage that it is possible to remove light efficiently from the back surface.

However, as one of the problems of the conventional belt-shaped photoreceptor, it is recognized that curling is easy. If the belt-shaped photoreceptor curls and the surface of the photoconductive layer loses its flatness, the distance between the photoconductor layer and a device around the belt such as a charging device and a developing device in the copying machine becomes uneven. This causes uneven charge potential during the charging process, uneven focus during the exposure process, and scumming during the developing process. In order to solve these problems, as an anti-curl layer, for example, an anti-curl layer containing a reaction product of a film-forming binder, crystal particles and a bifunctional chemical binder (JP-A-62-100764), the back surface of a substrate. An anti-curl layer comprising a resin layer having a specified film thickness (Japanese Patent Laid-Open No. 64-29).
851), an anti-curl layer made of polysulfone resin and polyarylate resin (JP-A-64-76065), an anti-curl layer containing a resin having a specific linear expansion coefficient as a main component (JP-A-1-223467), and the like. A method has been proposed.

However, the conventional anti-curl layer is peeled off from the support after being used for a long time in a copying machine, leaving many problems in its adhesiveness. Also,
As a means for solving this adhesiveness, a method of providing an adhesive layer between the support and the anti-curl layer (Japanese Patent Laid-Open No. 62-2807).
52) is also proposed, but it has a drawback that the cost increases due to the increase in the manufacturing process. As described above, a curl-preventing layer that can prevent curling of the photoreceptor at a low cost, improve the adhesion between the support and the curl-preventing layer, and can withstand long-term use has not yet been completed. .

[0005]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the prior art and has an excellent surface property that the anti-curl layer does not peel off from the support even when used for a long period of time. An object of the present invention is to provide a flexible electrophotographic photosensitive member which is easily attached to the main body and is easy to handle.

[0006]

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, there is provided a flexible electrophotographic photoconductor characterized in that the curl prevention layer contains at least one resin selected from the following resin (A) group and a resin (B). Resin (A) (a) Polysulfone resin (b) Polyarylate resin (c) Polycarbonate resin (d) Polyester carbonate resin represented by the following repeating unit (Formula 1)

[Chemical 1] Resin (B) Styrenic thermoplastic elastomer

A feature of the present invention is that at least one resin selected from the above-mentioned resin (A) group and a resin (on the surface of the support opposite to the photosensitive layer including the photoconductive layer, that is, the back surface of the support. It is provided by mixing with B).

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. The curl can be prevented by providing a layer that expands or contracts to the same extent as the photosensitive layer including the photoconductive layer on the back surface of the curl support which is generated due to a difference from the above. Secondly, the adhesiveness when it is directly provided on the back surface of the support must be at a level where there is no practical problem in the copying machine. Thirdly, since the probability of breakage due to bending stress caused by rollers and the like in the copying machine and rubbing increases, the photoconductor is required to have flexibility including the backside layer of the photoconductor. Therefore, in order to obtain a flexible photoconductor that has good smoothness and flexibility and can withstand long-term use, it is necessary to satisfy the above three requirements. As a means for preventing curling, the same composition as the photosensitive layer, or a single layer of the same resin as the binder resin used in the photosensitive layer, or the binder resin used in the photosensitive layer It has been known so far to use a binder resin having a linear expansion coefficient equal to or close to that of, but these methods are not only disadvantageous in terms of cost, but also the entire photoreceptor The increase in thickness causes deterioration of flexibility, and in any of the methods, there is a problem in adhesiveness to the support.

As a material used for the photosensitive layer of the current organic photoreceptor, a polymer which exhibits photoconductivity and has sufficient mechanical strength and adhesiveness and excellent electrical characteristics is not known at present. Therefore, the photosensitive layer of most organic photoreceptors is formed by dispersing or compatibilizing one or more optically active, relatively low molecular weight organic materials, and optionally inorganic materials, in a polymer or resin. In practice, the photosensitive layer including the photoconductive layer does not directly contact the support, but the conductive layer,
In some cases, it is provided on the support with an undercoat layer (intermediate layer or adhesive layer) interposed therebetween. Based on these circumstances, the present inventors have earnestly studied a curl layer that effectively prevents curling and further improves the adhesiveness, and as a result, it has been found that the curl preventive layer has improved adhesiveness between the curl preventive resin and the substrate. It has been found that the above object can be achieved by using a layer composition in which an excellent resin is mixed.

That is, the present inventors have selected resin (A), that is, (a) polysulfone resin, (b) polyarylate resin, (c) polycarbonate resin, or (d) polyester carbonate resin, as the curling preventing resin. If it has excellent adhesiveness to the substrate, it will be treated as resin (B)
That is, a styrene-based thermoplastic elastomer, preferably a styrene-butadiene block copolymer resin, or a styrene-isoprene-based thermoplastic elastomer, or styrene-
It was found that an electrophotographic photoreceptor satisfying the above-mentioned requirements can be obtained by using an olefin-based thermoplastic elastomer, and the present invention has been completed.

The polysulfone resin (a) used in the present invention preferably has a structure having the following repeating unit (Chemical Formula 2) or (Chemical Formula 3).

[Chemical 2]

[Chemical 3]

As the (b) polyarylate resin, those having a structure having the following repeating units are preferably used.

[Chemical 4]

As the polycarbonate resin, one having a structure having the following repeating unit (Formula 5) or (Formula 6) is preferably used.

[Chemical 5]

[Chemical 6]

As the polyester carbonate resin, those having a structure having the following repeating units are preferably used.

[Chemical 1]

The mixing ratio of at least one resin selected from the group of resins (A) and the resin (B) varies depending on the resin species of the binder used in the photosensitive layer, but is 50: 50-9.
The range of 9: 1, preferably 70:30 to 95: 5 is good. When the proportion of the resin (B) is increased, the adhesiveness is improved, but a sea-island pattern is generated and the light transmittance of the anti-curl layer is lowered.

Further, one or more kinds of the resins of the resin (A) group and the resin (B) group may be used in combination. The curl prevention layer is provided by dissolving the resin (A) and the resin (B) in a solvent, applying the solution to the back surface of the support, and drying. In the present invention, the procedure for providing the anti-curl layer on the back surface of the support is not specified. That is, a layer containing a photoconductive layer may be provided on the surface of the support after the anticurl layer is provided, or an anticurl layer may be provided on the back surface of the support after the photoconductive layer is provided.

The curling by the photosensitive layer does not occur depending on the entire photosensitive layer (total composition, total film thickness) itself, but mainly in proportion to the ratio of the binder component contained in the photosensitive layer. . For example, when the film thickness of the photosensitive layer is 30 μm and the ratio of the binder (resin) is 60%, the effect of curling the photosensitive member is 30% for the resin single layer.
When x0.6 = 1.8 μm, it is almost equal to that.
On the other hand, the curl prevention layer, when a resin for preventing curling and a resin for imparting adhesiveness are mixed,
In the case of microscopically uniform mixing (so-called transparency), the curl amount decreases as the mixing ratio of the resin increases, but in the case of macroscopic dispersion mixing (so-called sea-island type), The curl amount does not decrease even if the mixing ratio of the resin increases.

In order to improve the adhesiveness without deteriorating the curling prevention function of the anti-curl layer, the film thickness of the anti-curl layer in which a resin for preventing curling and a resin for imparting adhesiveness are mixed. By making the film thickness to be the value obtained by the following formula, a more functionally sufficient curl preventing effect can be obtained. Kt (the weight ratio of the adhesive used in the photosensitive layer is K, the thickness of the photosensitive layer is t) Actually, curling does not need to be present at all, and the film thickness of the anti-curl layer is 0.8 in the above formula. ~ 1.2 times,
The effect is sufficient.

Examples of the flexible support used in the present invention include polyimide, polybutylene terephthalate, polyethylene terephthalate, and the like, with polyethylene terephthalate (PET) being particularly preferable.
The support may have a film thickness of 10 to 300 μm, preferably 75 to 150 μm.

In the present invention, a conductive layer is provided on one surface of the support, and the conductive layer is aluminum,
A metal thin film of nickel, chromium, titanium or the like, or an alloy thin film of these metals such as nichrome, hastelloy, inconel, stainless steel or the like is suitable. Further, a transparent conductive material of metal oxide type can 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 21180), CI Pigment Red 41 (CI 21200), CI Acid Red 52 (CI 45100) CI Basic Red 3 (CI 45210), azo having a carbazole skeleton. Pigments (described in JP-A-53-95033), azo pigments having a distyrylbenzene skeleton (described in JP-A-53-133445), and azo pigments having a triphenylamine skeleton (JP-A-53-132).
347), an azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728),
Azo pigments having an oxadiazole skeleton (JP-A-54-
No. 12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-22834), an azo pigment having a bisstilbene skeleton (JP-A-54-17).
No. 733), an azo pigment having a distyryloxadiazole skeleton (described in JP-A-54-2129), an azo pigment having a distyrylcarbazole skeleton (described in JP-A-54-14967). Azo pigments such as CI Pigment Blue 16 (CI 74
100) and the like phthalocyanine pigments; for example, CIVAT BROWN 5 (CI 73410), CIVAT Dye (CI 73030) and other indigo pigments; Argol Scarlet B (manufactured by Bayer), Induslen Scarlet R (manufactured by Bayer), etc. Perylene pigments, squaric dyes, hexagonal Se powders, and the like.

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 by a method such as a bead coating method, a nozzle coating method, a blade coating method, a dipping method or a spray method, and dried 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 in the main chain or side chain, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, triazole. Compounds having a nitrogen-containing cyclic compound such as, triphenylamine compounds, hydrazone compounds (JP-A-55-467)
No. 60), 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, phenol resin, alkyd resin, and other thermoplastic or thermosetting resins, as well as 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 layer. 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 can be provided on the uppermost layer, if necessary.

[0026]

The present invention is explained in more detail by the following examples, which are merely illustrative, and the present 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 Polysulfone resin (P-350 manufactured by Nissan Chemical Industries, Ltd.)
0) 900 parts and styrene-butadiene block copolymer resin (Asaflex-805 manufactured by Asahi Kasei Corporation)
Dissolve 100 parts in 9000 parts tetrahydrofuran,
An anti-curl layer forming liquid was prepared. This liquid is 100 μm
Was coated on a polyethylene terephthalate film support having the above thickness and dried to provide an anti-curl layer having a thickness of 14 μm. Next, aluminum having a thickness of about 1000Å 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, alcohol-soluble copolymer nylon (CM-8000 Toray) 2
40 parts was dissolved in 3000 parts of methanol and 300 parts of butanol to prepare an undercoat layer forming liquid, which was applied onto the above conductive layer by the beat coating method and dried to form an undercoat layer having a thickness of about 1 μm. It was Next, 13.5 parts of the compound of the following structural formula (Formula 7), polyvinyl butyral resin (XY
HL UCC) 5.4 parts and tetrahydrofuran 3
After kneading and dispersing 60 parts in a ball mill for 72 hours, 211 parts of tetrahydrofuran and 356 parts of ethylene glycol monoethyl ether were further added and kneaded and dispersed for 1 hour.
A charge generation layer forming liquid was prepared by diluting with 110 parts of tetrahydrofuran and 664 parts of ethylene glycol monoethyl ether.

[Chemical 7] This solution was applied onto the undercoat layer by the bead coating method and dried to form a charge generation layer having a thickness of about 0.5 μm. further,
935 parts of the compound of the following structural formula (Formula 8) and 1039 parts of a polycarbonate resin (manufactured by Panlite C-1400 Teijin Ltd.) are dissolved in 7900 parts of tetrahydrofuran to prepare silicone oil (KF-50 manufactured by Shin-Etsu Chemical Co., Ltd.) (1% tetrahydrofuran solution). ) 2 parts was added to prepare a charge transport layer forming liquid.

[Chemical 8] This liquid is applied onto the charge generation layer by the nozzle coating method,
After drying, a charge transport layer having a thickness of about 25 μm was provided to prepare an electrophotographic photoreceptor of the present invention.

Example 2 The same as Example 1 except that the polysulfone resin, which is the component for forming the curl prevention layer, was replaced with a polyarylate resin (U4015 manufactured by Unitika Ltd.) and the film thickness was changed to 15 μm. Then, an electrophotographic photosensitive member of Example 2 was prepared.

Examples 3 and 4 Polycarbonate resin (C140 manufactured by Teijin Chemicals Ltd.)
0) 850 parts and styrene-butadiene block copolymer resin (Asaflex-805 manufactured by Asahi Kasei Kogyo Co., Ltd. or Clearlen-730L manufactured by Denki Kagaku Kogyo Co., Ltd.) 1
50 parts and 50 parts each were dissolved in 9000 parts of tetrahydrofuran to prepare the curl preventing layer forming liquids of Examples 3 and 4. This solution was applied onto a polyethylene terephthalate film having a thickness of 100 μm on a support and dried to form anti-curl layers having film thicknesses of 16 μm and 14 μm, respectively. Hereinafter, the conductive layer, the undercoat layer, and the photosensitive layer are the same as those in Example 1.
Electrophotographic photoreceptors of Examples 3 and 4 were prepared in the same manner as in.

Example 5 In Example 3, the polycarbonate resin which is a component of the curl prevention layer forming liquid was replaced with a polycarbonate resin (Z-TYPE manufactured by Teijin Chemicals Ltd.), and the film thickness was 15 μm.
An electrophotographic photoreceptor of Example 5 was prepared in the same manner as in Example 1 except that the above was adopted.

Examples 6 and 7 Polyester carbonate resin (P1000 manufactured by Mitsubishi Gas Chemical Co., Inc.) and styrene-butadiene block copolymer resin (Asaflex-825 manufactured by Asahi Kasei Co., Ltd.)
The ratios of 800 parts and 200 parts and 700 parts and 300 parts were dissolved in 9000 parts of tetrahydrofuran to prepare the curl preventing layer forming liquids of Examples 6 and 7. This solution was applied onto a polyethylene terephthalate film having a thickness of 100 μm and dried to form an anti-curl layer having film thicknesses of 16 μm and 17 μm, respectively. Hereinafter, electroconductive photoreceptors, subbing layers and photosensitive layers were prepared in the same manner as in Example 1 to prepare electrophotographic photoreceptors of Examples 6 and 7.

Examples 8 and 9 Polyarylate resin (U4015 manufactured by Unitika Ltd.)
900 parts and styrene-olefin thermoplastic elastomer (Tuftec H1051 manufactured by Asahi Kasei Co., Ltd.) or styrene-isobutylene thermoplastic elastomer (JSR SIS5000 manufactured by Japan Synthetic Rubber Co., Ltd.) 1
50 parts and 50 parts each were dissolved in 9000 parts of tetrahydrofuran to prepare the curl preventing layer forming liquids of Examples 8 and 9. This solution was applied onto a polyethylene terephthalate film support having a thickness of 100 μm and dried to provide a curl prevention layer having a thickness of 17 μm. Hereinafter, the conductive layer,
As the undercoat layer and the photosensitive layer, the electrophotographic photosensitive members of Examples 8 and 9 were prepared in the same manner as in Example 1.

Comparative Example 1 1000 parts of the polysulfone resin used in Example 1 was dissolved in 9000 parts of tetrahydrofuran to prepare a curl preventing layer forming liquid of Comparative Example 1. 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 14 μm.
Hereinafter, the conductive layer, the undercoat layer, and the photosensitive layer were the same as in Example 1 to prepare the electrophotographic photosensitive member of Comparative Example 1.

Comparative Example 2 Comparative Example 1 was compared with Comparative Example 1 except that the polyacrylate resin used in Example 2 was used instead of the polysulfone resin which was the component for forming the curl prevention layer, and the film thickness was 12 μm. An electrophotographic photosensitive member of Example 2 was prepared.

Comparative Example 3 Comparative Example 1 was carried out in the same manner as in Comparative Example 1 except that the polycarbonate resin used in Example 3 was used instead of the polysulfone resin which was the component for forming the curl prevention layer, and the film thickness was 14 μm. The electrophotographic photoconductor of No. 3 was prepared.

Comparative Example 4 Comparative Example 1 except that the polysulfone resin, which is the component for forming the anti-curl layer, was replaced with the polyester carbonate resin used in Example 4 and the film thickness was changed to 13 μm.
An electrophotographic photoreceptor of Comparative Example 4 was prepared in the same manner as in. The curl amount and the adhesiveness of the curl preventive layer of the flexible electrophotographic photoreceptors prepared in the above Examples and Comparative Examples were evaluated as follows. The curl amount was obtained by cutting the photosensitive member into a size of 10 × 10 cm, placing it on a surface plate, and measuring the amount with a height gauge. For the adhesiveness, the 90 ° peeling test method (the photoconductor was cut into 5 × 10 cm, and the photoconductor was fixed on a surface plate with double-sided tape. Next, part of the shorter end face of the pack coat layer was peeled off. The tension is read while pulling up 90 ° in the longitudinal direction with a spring.).
The results are shown in Table 1.

[Table 1]

[0037]

The present invention has at least a conductive layer and a photoconductive layer on a flexible film-shaped support,
Further, in the flexible electrophotographic photosensitive member having a curl prevention layer on the back surface of the support, since the curl prevention layer contains the resin (A) and the resin (B), the curl prevention layer can be used for a long period of time. Does not peel off from the support, has excellent surface smoothness, and can be a photoreceptor having abundant flexibility. Further, the electrophotographic photosensitive member of the present invention is easy to install in the main body of the copying machine and has excellent handling property, and its practical value is extremely high.

Claims (3)

[Claims] 1. A flexible film-shaped support,
In a flexible electrophotographic photoreceptor 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 comprises at least one kind selected from the following resin (A) group. A flexible electrophotographic photosensitive member comprising a resin and a resin (B). Resin (A) (A) Polysulfone resin (B) Polyarylate resin (C) Polycarbonate resin (D) Polyester carbonate resin represented by the following repeating unit (Chemical formula 1) Resin (B) Styrenic thermoplastic elastomer 2. The flexible electrophotographic photosensitive member according to claim 1, wherein the resin B is a styrene-butadiene block copolymer resin. 3. The flexible electrophotographic photosensitive member according to claim 1, wherein the resin B is a styrene-olefin thermoplastic elastomer or a styrene-isoprene thermoplastic elastomer.