JPH0255366A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, an electrophotographic photoreceptor in which the surface layer contains fluorine-containing resin powder and the photosensitive layer below contains an antioxidant. Regarding photoreceptors.

[Conventional technology]

Electrophotographic photoreceptors are required to have predetermined sensitivity, electrical properties, and optical properties depending on the electrophotographic process to which they are applied. The surface layer of the electrophotographic photoreceptor, that is, the layer furthest from the support, is directly subjected to electrical and mechanical external forces such as corona charging, toner development, transfer to paper, and cleaning processing, so durability against these forces is limited. is required.

Specifically, surface wear and scratches caused by rubbing.

Additionally, durability against surface deterioration due to ozone generated during corona charging under high humidity conditions is required. Furthermore, there is a problem of toner adhesion to the surface layer due to toner development and cycling during cleaning, and to solve this problem, it is required to improve the cleaning performance of the surface layer.

Various methods have been studied to satisfy the above-mentioned properties required for the surface layer, and among them, it is possible to provide a resin layer in which fluorine-containing resin powder is dispersed on the surface of the electrophotographic photoreceptor. Particularly effective.

By providing a resin layer in which fluorine-containing resin powder is dispersed on the surface of the electrophotographic photoreceptor, durability against scratches, surface cleaning, abrasion, etc. is improved, and water repellency and mold release of the surface of the electrophotographic photoreceptor are improved. It is also effective in preventing surface deterioration under high humidity conditions.

On the other hand, when an electrophotographic photoreceptor is used according to the electrophotographic process to which it is applied, in addition to the physical impact it receives from the process, it also suffers from fatigue due to repeated exposure.
Or they are exposed to ozone, nitrogen oxides, etc. generated by corona discharge.

In particular, ozone and nitrogen oxides directly chemically act on the charge transport material on the surface of the electrophotographic photoreceptor, lowering the surface resistance and affecting one image. In order to prevent this, it is effective to use a charge transporting material with a high oxidation potential and heat it to make it less likely to react with the ozone and nitrogen oxides.

But especially when it comes to nitrogen oxides.

In addition to acting on the electrophotographic photoreceptor in a gaseous state, it also acts on the electrophotographic photoreceptor in the form of nitric acid when combined with moisture in the air.

Especially near the corona charger, a large amount of nitric acid is generated.
This adheres to the corona charger, moves onto the electrophotographic photoreceptor while the machine is stopped for a long time, enters the electrophotographic photoreceptor, and reaches the support, so the area under the charger becomes electrically charged. This caused a decrease in performance, a change in sensitivity, and a phenomenon in which the parts had different characteristics from those of other parts.

In order to prevent these phenomena from occurring, studies have been made to add antioxidants to the surface layer to inactivate ozone, nitric acid, etc. that enter the electrophotographic photoreceptor. It has had good effects.

[Problem to be solved by the invention]

If the above two types of technologies are combined, 1 mechanical properties 1
An electrophotographic photoreceptor with excellent surface lubricity and wettability should be produced. However, in reality, good things are not always possible.・This is because the fluororesin powder discussed here has extremely poor dispersibility when dispersed in a binder resin, and in order to achieve uniform dispersion, it is almost always necessary to use a surfactant as a dispersion aid. It can be said that it is essential.

However, in electrophotography, if both the surfactant and the antioxidant are present in the same layer of the electrophotographic photoreceptor, their interaction will have an adverse effect on the electrophotographic properties of the electrophotographic photoreceptor, resulting in a decrease in sensitivity, for example. decline.

This causes an increase in residual potential and an increase in potential fluctuation due to durability.

It is an object of the present invention to overcome the above-mentioned drawbacks, to have durability and moisture resistance against surface abrasion and scratches caused by rubbing during use, and to provide moisture resistance against partial scratches caused by the above-mentioned nitric acid, etc. An object of the present invention is to provide an electrophotographic photoreceptor that does not cause image unevenness due to uneven chargeability or uneven sensitivity.

Another object of the present invention is <Shigaeshi IF! An object of the present invention is to provide an electrophotographic photoreceptor with high quality and particularly high sensitivity in terms of photogloss.

[Means to solve the problem]

In the present invention, as a result of repeated studies in accordance with these objectives, the 'stM It has become possible to solve the above problems by providing an electrophotographic photoreceptor having this structure.

That is, the present invention provides an electrophotographic photoreceptor having a conductive support, a photosensitive layer, and a surface layer, wherein the surface layer contains a binder and fluorine-containing resin powder dispersed therein, but also contains an antioxidant. First, it is an electrophotographic photoreceptor in which the layer on the side of the laminated photosensitive layer in contact with the surface layer or the single layer photosensitive layer contains an aromatic amine antioxidant.

In the present invention, the fluorine-containing resin powders include tetra7ethylene ethylene, trifluorinated ethylene, ethylene/hexafluoropropylene, divinyl fluoride, vinylidene fluoride, ethylene dichloride difluoride, trifluoroethylene Resin powder of a polymer such as bilmethyldichlorosilane, a copolymer thereof, or a copolymer of these and vinyl chloride can be used as appropriate.

Particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin. The molecular weight of the resin and the particle size of the powder are selected within a range that does not affect the uniformity of the coating film formed. Specifically, the average particle diameter is 2 μm or less, preferably 1 μm or less. The content of the dispersed fluororesin powder is suitably 1 to 50% by weight based on the total solid content of the surface layer. Content rate is 1
If there is less than ts, sufficient effect may not be obtained<<, and 5
If it exceeds 0%, electrophotographic properties will be adversely affected. The Pine Goo resin used for dispersion may be any polymer that has film-forming properties, but polymethacrylate ester is used because it has a certain degree of hardness even when used alone and does not interfere with carrier transport. , polycarbonate,
Polyarylate, polyester? Preferred are resulfone, vinyl chloride/vinyl acetate copolymer, I-restyrene, and the like.

The surface layer in which the fluorine-containing resin powder is dispersed in the binder does not necessarily need to be treated only as a protective layer. That is, this surface layer may contain a charge transport material and function as part of the charge transport layer, or it may contain a charge generation material and function as part of the charge generation layer, and the surface layer may contain a charge transport material and function as part of the charge generation layer. The same charge transport material as the charge transport layer or charge generation layer of /
It can also be a binder ratio or a charge generating material/binder ratio. The amount of charge transporting material or charge generating material to be included can be appropriately selected depending on the performance of the electrophotographic photoreceptor. Even when the surface layer contains a charge transporting material or a charge generating material, the effect of the fluororesin powder is fully exhibited.

In the electrophotographic photoreceptor of the present invention, the photosensitive layer may be of a single-layer type, or may be of a laminated type with functions separated into a charge generation layer and a charge transport layer. In addition, in the case of a laminated type, even if the conductive support, charge generation layer, °α charge transport layer and surface layer are laminated in this order, or the order of the charge generation layer and charge transport layer is reversed. Good too.

In the present invention, the aromatic amine antioxidant is

When the photosensitive layer is a single layer type, it is contained in the entire photosensitive layer.

In the case of a laminated type, when the layer 1 in contact with the surface layer is laminated in the order of the conductive support, the charge generation layer, the charge transport layer, and the surface layer, it is contained in the charge transport layer. However, it may be contained in both the charge transport layer and the charge generation layer.

The amount of the aromatic amine antioxidant to be added is preferably 0.1 to 10 mol based on the charge transport material in the layer to which it is added, and if it is less than 0.1 mol, sufficient effects may not be obtained. , if it exceeds 10 molt, it will adversely affect the electrophotographic properties.

Examples of aromatic amine antioxidants that can be used in the present invention include the following: When producing the electrophotographic photoreceptor of the present invention, any conductive support can be used as long as it has conductivity. For example, a cylindrical cylinder or film made of metal such as aluminum or stainless steel, or made of glass, paper, etc., coated with a conductive material alone or together with a suitable binder resin to provide a conductive layer can be used. A subbing layer (adhesive layer) having a barrier function and a subbing function can also be provided on these conductive supports. The subbing layer improves the adhesion of the photosensitive layer, improves coating properties, and protects the support.

It can be formed for purposes such as covering defects on the support, improving charge injection from the substrate, and protecting the photosensitive layer from electrical breakdown.

The material for the undercoat layer is polyvinyl alcohol.

Poly-N-vinylimidazole, polyethylene oxide, ethylcellulose, methylcellulose.

Known examples include ethylene-7-grily acid copolymer casei/polyamide, copolymerized nylon, glue, and gelatin. These are each dissolved in a suitable solvent and applied onto a support. The film thickness is about 0.2 to 2.0 μm.

As charge generating materials, biryllium-based dyes, thiapyrylium-based dyes, phthalo-7-anine pigments, anthoanthrone pigments,
Dibenzpyrenequinone pigments, vilanthrone pigments, trisazo pigments, sosazo pigments, azo pigments, in-novo pigments, quinacridone pigments, asymmetric quinocyanine, quinocyanine, and the like can be used.

Charge transport substances include pyrene, N-ethylcarbazole, N-(sopropylcarbazole; N-methyl-N-phenylhydrazino-3-methylane-9-ethylcarbazole, N,N-nophenylhydrano-3-methylane). -9-Ethylcarbazole, N,N-diphenylhydrazono-3-methylane-10-ethylphenothianone, N,N-nobenylhydrazono-3-methylane-
10-Ethylphenoxacin, p-noethylaminopenzaldehyde N, N-nophenylhydrazone, p-noethylaminopenzaldehyde N-α-naphthyl-N
-7enylhydrazone, p-virolizonopenzaldehyde N, N-diphenylhydrazone, 1゜3,3-trimethylindolenine-α-A/7'' human-N, N-zophenylhydrazone, p-diethylbenzaldehyde −
Hydrazones such as 3-methylbenzthiazolinone-2-hydrazone: 2,5. Bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, l-[quinolyl (2) E-3-CP-diethylaminostyryl)-
5-(p-diethylaminophenyl)pyrazoline, 1-
(Pyridyl (2)) -3-(p-diethylaminostyryl)-s-(p-diethylaminophenyl)pyrazoli/, 1-[6-methoxylbyrityl(2)-3-(p
-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-(pyridyl(3))
-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline.

1-[Lepidyl (2)]-3-(p-zoethylaminoxthiIJyl)-5-(p-f ethylaminophenyl)pyrazoline, 1-[Pyridyl(2))-3-(p-diethylaminostyryl) -4-Methyl-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2
]-3-(α-methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)hylasoline, 1-7E=3-Cp-zoethylaminostyryl)
Pyrazolines such as -4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-(α-benzo-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, and spiropyrazoli 7: 2- (p-diethylaminostyryl)-6-zoethylaminopenzoxazole, 2-(p-diethylaminophenyl)-4-CP-tumethylaminophenyl)-
Oxazole compounds such as 5-(2-chlorophenyl)oxazole; 2-(p-zoethylaminos-y-1)
)-thiazole compounds such as 5-noethylaminopenzothiazole; triaryl meta/compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane:, 1,1-bis(4-N , N-diethylamino-2-methylphenyl)butane% 1.1, 2.2
-tetrakis(4-N,N-dimethylamino-2-meth
A/ Polyarylal-h7 such as phenyl)ethane
etc. can be used.

In the present invention, as a method for dispersing the fluororesin powder in the resin solution, methods such as a homogenizer, an &-luminum, a vibratory lumill, a sand mill, and an attritor roll mill can be used.

The procedure involves dissolving the binder resin in an organic solvent.

Mix the required amount of fluororesin powder and dispersion aid to this,
Disperse using the above dispersion method and mix the charge transport material and charge generation material into the resulting dispersion. If the charge generation material is a pigment, add only the charge generation material according to the dispersion conditions of the charge generation material. A dispersion of the charge generating material may be prepared and then mixed with a dispersion of the fluororesin powder, or if conditions permit, this charge generating material may be dispersed simultaneously with the fluororesin powder.

When manufacturing the electrophotographic photoreceptor of the present invention, coating methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, and curtain coating are used to coat each layer. be able to. Especially when applying a surface layer in which fluororesin powder is dispersed.

If the underlying layer and the binder are of the same type of resin, or even if they are not of the same type but the solvent used for one will dissolve the other, dip coating methods etc. may not be usable. Spray coating method etc. are suitable.

The thickness of the surface layer after coating and drying can be adjusted to an appropriate thickness depending on the purpose. In particular, in systems containing a charge transport material or a charge generation material, the surface layer also functions as a charge transport layer or a charge generation layer, respectively, so electrophotographic properties can be maintained even if the coating is thicker than a general protective layer. It will not deteriorate.

Examples are shown below.

Example 1 A 5-time methanol solution of a quaternary polyamide copolymer resin of 6-6.6-6.10-1.2 was placed on an aluminum cylinder support with a diameter of 80 mm and a length of 360 mm. A subbing layer with a thickness of 0.5 μm was provided by coating by dipping.

Next, 12 parts of the charge generating material with the structural formula, 4! Rivinyl Penzal Resin 6
part and 60 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using a 1 m+φ Rusby and e. 120 parts of tetrahydrofuran was added to this dispersion and mixed, and this mixed solution was applied onto the undercoat layer to form a 0.2 μm charge generation layer.

Next, 10 parts of the charge transporting material represented by the formula and 10 parts of bisphenol Z-type polycarbonate resin were dissolved in 70 parts of a mixed solvent of monochlorobenzene and dichloromethane, and the aromatic amine oxidation material of Grave 3 in the table above was added to the mixture. The inhibitor was added and dissolved in an amount of 1 mol % with the charge transport material. This solution was applied onto the charge generation layer by dip coating and dried with hot air at 120°C to form a charge transport layer with a thickness of 17μ.Next, a low molecular weight polytetrafluoride with an average primary particle size of 0.3μ 5 parts of ethylene powder, 0.5 parts of a fluorine-based comb-shaped graft polymer with fluoroalkylate in its side chain as a dispersion aid
5 parts of bisphenol ZW polycarbonate having a number average molecular weight of approximately zoooo as a binder were mixed with 35 parts of monochlorobenzene and dispersed in a ball mill for 50 hours.To this dispersion, 52 parts of the charge transport material described above was mixed.
50 parts of polycarbonate, 70 parts of monochlorobenzene
0 parts and 7100 parts of dichloromethane to form e,
Coat it on the charge transport layer using an air spray coating device, and
It was dried at 20° C. to form a 5 μm surface layer.

This electrophotographic photoreceptor is referred to as sample 1.

Sample 2.1 had a charge transport layer with a thickness of 22 μm without coating one surface layer. Sample 10 When preparing the surface layer coating solution, the amount of the solvent to be added later was 300 parts of monochlorobenzene and 50 parts of nochloromethane, and the amount of 1 mol% of the charge transport material added to this was A3 in the above table. Sample 3. was prepared by adding and dissolving an aromatic amine-based antioxidant, applying this dispersion mixture onto the charge generation layer, and drying it at -120°C to form a charge transport layer with a thickness of 22μ. Sample 4 is Sample 3 in which no antioxidant is added to the charge transport layer.

These samples 1 to 4 were installed in a dry plain paper copying machine, and conditions were set so that the dark area potential was 650 V and the bright area potential was 130 V. An electrophotographic process consisting of transfer and cleaning with a rubber blade was carried out, and the images were evaluated after being used for 30,000 copies. The results were as follows.

Next, after long-term use, these electrophotographic photoreceptors were left in a copying machine for 24 hours and the images were evaluated again. In sample 4, the sensitivity of the portion facing the corona charger was apparently increased by 1, and a halftone image was produced, and that portion turned white in the form of a band. In other words, only sample 1 did not exhibit any scratches, white capri, or band-like white spots after being used for 30,000 sheets.

Example 2 In the method of Example 1, polyvinylidene fluoride powder was used as the fluororesin powder, and a fluorine-based block polymer tM consisting of a #-fluoroalkyl group moiety and an acrylic resin was used as the dispersion aid.

Similar results were obtained when the aromatic amine antioxidant of Grave 8 in the table above was used as the antioxidant.

Example 3 An aluminum 7-liner measuring 80° x 360° was used as a support, and a 5-thimethanol solution of the boriabad resin used in Example 1 was dip-coated onto the support to provide a 1 μm subbing layer.

Next, 1 part of the charge generating material represented by the structural formula and 10 parts of bisphenol z-type polycarbonate were added to 60 parts of monochlorobenzene, and this mixture was dispersed in a stainless steel M-Lumil for 72 hours. Six parts of the charge transport material used was added and dissolved.

Furthermore, 1.5 molty of aromatic amine type antioxidant (&12) in the table above was added to this solution based on the charge transport material. This solution was dip coated onto the undercoat layer to provide a 15μ exposure.

Next, we used the same method and ingredients to make this photosensitive layer coating solution, except that no antioxidant was added, and we used stainless steel! ! ! When dispersing in a hole mill, 4 parts of polytetrafluoroethylene resin powder and 0.4 part of a fluorine-based comb-shaped graft polymer consisting of a perfluoroalkyl group and a styrene resin are simultaneously added as a dispersion aid and dispersed. A dispersion containing a charge transport material was prepared. Monochlorobenzene was further added to this dispersion to obtain a solution having a coating fraction of 10. This was coated onto the photosensitive layer using a spray coating device and dried at 120C to form a surface layer of 5μ.

The electrophotographic photoreceptor thus produced is designated as sample 5.

Also, sample 6. has a photosensitive layer with a thickness of 20μ and no surface layer. Sample 7 was Sample 5 in which no antioxidant was added to the photosensitive layer. Further, when providing a photosensitive layer, sample 8 contained both polytetrafluoroethylene resin powder and an antioxidant in the photosensitive layer.

These electrophotographic photoreceptors of Samples 5 to 8 were placed in a plain paper copying machine in the same manner as in Example 1, and subjected to e-corona charging 8 image exposure, dry toner development, transfer to plain paper, cleaning with a rubber blade, An image production durability test was conducted using a process of removing the surface potential using strong-motion light. The image evaluation after 30,000 sheets is shown below. The residual potential of these photoreceptors after strong exposure was measured and was as follows.

Furthermore, in the same manner as in Example 1, these electrophotographic photoreceptors were
When the image was taken again after being left in the machine for a while, for sample 5.6%8, an image similar to that before being left was obtained, but for sample 7, the part corresponding to the corona charger was a halftone image. It was white and band-like.

Example 4 A 5% methanol solution of a quaternary polyamide copolymer resin of K 6-6.6-6.10-1.2 was immersed on an aluminum 7-ring support with a diameter of 80 mm and a length of 360 m. The entire undercoat layer was coated with a thickness of 0.5 μm.

12 parts of a charge transport material represented by the following formula, 10 parts of bisphenol 2 type polycarbonate) and 1.5 parts based on the charge transport material.
An antioxidant indicated by A4 in the above table in terms of the amount of mulch was dissolved in monochlorobenzene and applied by dip coating onto the above-mentioned undercoat layer to form a charge transport layer having a thickness of 18 microns.

Next, 10 parts of the charge generating material represented by the formula and 10 parts of bisphenol 2 type polycarbonate were added to 100 parts of a 1'l mixed medium of tetrahydrofuran/cyclohexanone = 1/l, and the average dispersed particle size of the charge generating material was reduced to 0 using a sand mill. It was dispersed until the particle size was .1μ or less. In this dispersion, 5 parts of the charge transport material and 1.5 molti of the AIO antioxidant listed in the above table based on the charge transport material were dissolved, and after dissolving, the charge transport layer was coated by spray coating. A charge generation layer having a thickness of 3 μm was formed by coating the film on the substrate. Additionally, 2 parts of pre-tetrafluoroethylene powder.

0.2 m of fluorine-based graft polymer and bisphenol 2 type polycarbonate used in Example 1? 8 parts of monochlorobenzene/dichloromethane = 7/3 (7) mixed solvent 1
00 parts and dispersed in a Gale mill for 50 hours. This dispersion was applied onto the stain generation layer by a spray coating method to form a 3 μm thick protective layer. The photoreceptor prepared in this manner is referred to as Sample 9. In addition, sample 10 is a sample 9 that does not have the protective layer. In addition, sample 11 contains no antioxidant in the charge transport layer and charge generation layer in sample 9.
And so. For these samples 9 to 11, ■ corona charging, latent image formation by image exposure, development with dry toner, 1
An electrophotographic process consisting of toner transfer to one sheet of paper, a cleaning process with a urethane 9-mole blade, and a process of removing residual potential using strong vibration light was used to produce images for 10,000 sheets, and the images and potential were evaluated after the durability. It became.

The part that corresponded to the area that was under the corona charger when it was left was a white band with approximately the same width as the "f! electric appliance. This was due to the nitric acid that had adhered to the charger while it was left. It is thought that the white stripe formed because it moved onto the photoreceptor and reached the support.

From this result, it was found that Sample 9 had excellent durability.

〔Effect of the invention〕

Since the electrophotographic photoreceptor of the present invention is constructed as described above, it has excellent mechanical properties, surface lubricity, moisture resistance, and durability.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having a conductive support, a photosensitive layer and a surface layer, the surface layer containing a binder and fluororesin powder dispersed therein, but containing no antioxidant;
Further, an electrophotographic photoreceptor characterized in that a layer of the laminated photosensitive layer in contact with the surface layer or a single layer photosensitive layer contains an aromatic amine antioxidant.