JPH01282560A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the durability in corona discharge environment and stable high-quality image by incorporating a charge transfer material having <0.6V oxidation potential and specified acetyl acetone metal complex into the surface layer of the photosensitive body. CONSTITUTION:The charge transfer material having <0.6V oxidation potential and the acetyl aceton metal complex specified by the formula I are incorporated into at least the layer furthest from a conductive base body i.e. the surface layer, of the photosensitive body formed by providing the photosensitive layer on the conductive base body. In the formula I, M is a metal atom; n is 1-4 integer. The specified acetyl acetone metal complex receives the oxidation effect of ozone and Nox preferentially from the charge transfer material and the oxidation deteriorating matter thereof does not adversely affect the other electrophotographic characteristics. The mechanical durability is, therefore, improved by adding various kinds of the lubricant powders to the surface layer, by which the stable high-quality image is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to electrophotographic copying machines, laser beam printers,
CRT printers, electrophotographic plate making systems, etc.
The present invention relates to an electrophotographic photoreceptor that can be widely used in photographic applications, and more particularly to an electrophotographic photoreceptor that is highly sensitive and has excellent durability.

[Conventional technology]

In recent years, the development of organic photoconductive materials as photoconductive materials for electrophotographic photoconductors (hereinafter abbreviated as photoconductors) has progressed, and in particular, functionally separated photoconductors in which a charge generation layer and a charge transport III are laminated have already been developed. It has been put into practical use and is installed in copiers and printers. However, one major drawback of these photoreceptors has been that they generally have low durability.

Does this durability affect sensitivity, residual potential, etc.? #Durability of electrophotographic physical properties such as electric power and image picket, and mechanical durability such as abrasion and scratches on the photoreceptor surface due to rubbing.Is the low durability of the former due to corona? # This is caused by the deterioration of the charge transport material contained in the surface layer of the photoreceptor due to ozone NOx etc. generated from electrical appliances. Particularly when the oxidation potential of the charge transport material is less than 0.6 V, this deterioration is significant, and as the image is used for long periods of time, the image becomes distorted and characters become indistinguishable, a phenomenon called so-called image pickling. Therefore, in order to obtain high-quality images, it is essential to polish the surface of the photoreceptor to always present a fresh surface. However, as attempts were made to improve mechanical durability by dispersing various lubricants on the surface of the photoreceptor, the amount of abrasion decreased significantly, and the deteriorated charge transport material could no longer be removed promptly.
Currently, the occurrence of image picketing has become evident.

The present inventors have discovered that it is effective to use a compound with an oxidation potential of 0.6 V or more as a charge transport material contained on the surface as a solution to these problems, and have put a highly durable photoreceptor into practical use. However, new problems have been pointed out depending on how the photoreceptor is used. In other words, if the photoreceptor is left in the copier for a long time after being used continuously,
A phenomenon occurs in which the charging ability of the photoreceptor in the vicinity of the charger that performs corona discharge appears to be lowered, resulting in the appearance of white streaks on the image, so-called white spots. This day drop phenomenon is a unique phenomenon that appears when a charge transport material with an oxidation potential of 0.6 V or more is used.
．． This is not seen at all in charge transport materials with low oxidation potentials of less than 6V.

It is believed that the above-mentioned image pickling and the occurrence of white spots are both caused by ozone and NOx generated during corona discharge. In other words, when the oxidation potential of the charge transport material is less than 0.6 V, the 1jtt charge transport material itself is oxidized on the surface of the photoreceptor by the action of ozone and NOx and becomes low in resistance, causing image pixelation. Charge transport materials with a voltage of 0.6 V or higher are not susceptible to oxidation, so ozone and NOx penetrate deep into the photoreceptor and oxidize the charge-generating materials, lowering their resistance. As a result, holes are injected from the substrate. It is presumed that this promotes the appearance of the upper potential and that a white-out phenomenon occurs. This apparent potential drop occurs even during durable use, but it is not observed as a sun drop phenomenon, which is a partial potential drop because the surface potential drop occurs uniformly on the surface of the photoreceptor. However, when the charger is left unattended after continuous use, the local potential drop near the charger where ozone and NOx concentrations are extremely high becomes noticeable as white spots.

[Problems to be solved by the present invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor capable of producing high-quality images without scratches or white spots.

Another object of the present invention is to provide an electrophotographic photoreceptor with high durability, which has less surface wear and scratches caused by rubbing, and which can provide high-quality images without image pickling or white spots. be. Still another object of the present invention is to provide an electrophotographic photoreceptor that does not accumulate residual potential during repeated electrophotographic processes and can always produce high-quality images.

[Means for Solving All Problems] As a result of extensive studies in accordance with the above objectives, the present inventors found that acetylacetone, which has a special structure, can be used even in photoreceptors using charge transport materials with an oxidation potential of less than 0.6V. It was discovered that by adding a metal complex to prevent its deterioration, a photoreceptor without image pickling could be obtained, and the present invention was completed. In the photoreceptor, at least the I@ farthest from the conductive support, that is, the surface layer, contains a charge transport substance with an oxidation potential of less than 0.6 V and an acetylacetone metal complex represented by the following general formula (1). The present invention provides a photoreceptor with

However, in the above formula, Mf'i metal atom and n are integers of 1 to 4.

In the present invention, the effect of adding the acetylacetone metal complex of general formula (1) above is that the charge transport substance is
Its purpose is to protect against the oxidative effects of

In other words, it has been found that the acetylacetone metal complex specified in the present invention is preferentially oxidized by ozone and NOx over charge transport substances, and its oxidized deterioration products do not have any adverse effects on other electrophotographic properties. It was done.

Further, in the photoreceptor of the present invention, since there is no deterioration of the charge transport substance, mechanical durability (reduction in the amount of abrasion of the surface layer) can be improved by adding various lubricant powders.

The present invention will be explained in more detail below.

In the photoreceptor of the present invention, the photoreceptor layer may be a single layer containing a charge-generating substance and a charge-transporting substance, but a functionally separated photoreceptor is preferable. That is, the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, and the charge generation layer is coated on the charge transport material, or conversely, the charge transport layer is coated on the charge generation layer. Of these, the latter is preferred.

Examples of the charge-generating substance used in the present invention include pi-1,11Jium, thiopyrylium dyes, 7-talocyanine pigments, anthoanthrone pigments, perrine pigments, dibenzpyrenequinone pigments, pyranthrone pigments, triazo pigments, disazo pigments, monoazo pigments, Examples include indib pigments and quinacridone pigments, and two or more of these can also be used in combination.

When a charge generation layer is formed, the charge generation material is dispersed in a suitable binding agent and the layer is coated, or it is formed by vapor deposition using a vacuum evaporation apparatus. The film thickness is preferably 0.01 to 1 μm.

Further, as charge transport substances having an oxidation potential of less than 0.6 V used in the present invention, hydrazone compounds, stilbene compounds, carbazole compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, Examples include I-realylalkanes, and 12 or more of these F1 types can also be used in combination. The amount added is preferably 10 to 50,031 parts (fi parts) per 100 parts by weight of the binding agent binder.

Note that charge transport materials generally have a low molecular weight and cannot be used to form a film by themselves. Therefore, it is necessary to use a resin having film-forming properties as a binder. This binder may be any polymeric compound with film-forming properties, but polymethacrylates, polycargonates, polyarylates are preferred because they have a certain degree of hardness even when used alone and do not interfere with carrier transport. , polyester, polysulfone, etc. are preferred.

Next, in the acetylacetone metal complex used in the present invention, in the general formula (1), the metal M is Zn, N
i*Co, Cu, Pb, Cu, C
Examples include compounds such as r, and it is also possible to use two or more of these in combination.

The amount added is 0.0% by weight relative to the surface layer of the photoreceptor.
05-20.0% is appropriate, preferably 0.1-1
The range is 0.0%. If the amount added is less than 0.05%, the effect of preventing image R on the photoreceptor will not be sufficient;
Exceeding this results in an increase in residual potential (fogging on the image).

When constructing the photoreceptor of the present invention, the conductive support is made of a material that itself has conductivity, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, etc. , nickel, indium, gold, platinum, etc.Also, even if the support itself is not conductive, it has a conductive layer on one side or inside, such as aluminum, aluminum alloy, indium oxide, tin oxide, and indium oxide. - A glass film coated with a tin oxide alloy or the like by vacuum evaporation, a plastic film coated with carmen plaque, silver particles, etc. together with a suitable binder, or the above-mentioned conductive support;
Examples include paper and plastics impregnated with conductive substances, and plastics containing conductive polymers, as well as metal powders such as copper and aluminum, and powders such as carmen plaque, tin oxide, antimony oxide, and titanium oxide in the binder. It is also possible to use a support coated with a dispersed dye, and in this case, the binder is phenol resin,
Examples include urethane resin, epoxy resin, phenoxy resin, polyvinyl alcohol, acrylic resin, and polyamide.

Further, in the photoreceptor of the present invention, an undercoat layer having both a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. This undercoat layer.

Casein, yjflJ vinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, I-lyamide (nylon 6,
It can be formed from nylon 66, nylon 610° copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is generally 0.1 to 40 μm, preferably 0.3 to 40 μm.
3 μm is appropriate.

The lubricant powder used in the present invention includes fluororesin powder, polyolefin resin powder, and fluorinated carbine powder, and two or more of these can also be used in combination. Fluorine-based resin powders include tetra7fluoroethylene resin, trifluorochloroethylene resin, hexafluoroethylene propylene street resin, and fluorinated vinyl street resin.

Examples include powders of vinylidene fluoride resin, ethylene difluoride dichloride, and copolymer resins thereof.

Examples of the polyolefin resin powder include powders of I-lyethylene, polypropylene, and copolymer resins thereof.

The amount of lubricant powder added to the surface layer of the photoreceptor of the present invention is 0.
．． A range of 5 to 50 i is preferred. The amount added is 0.
If the amount of M is less than 5%, the mechanical durability of the photoreceptor will not be sufficient, and if it exceeds 50% by weight, the light transmittance will decrease.
Furthermore, carrier mobility is reduced, which is not preferable.

On the other hand, the photosensitive layer can be coated on the conductive support by a dip coating method, a spray coating method, a spinner coating method, a bead coating method, or a Meyer bar coating method.

This can be carried out using a coating method such as a blade coating method, a roller coating method, or a curtain coating method. In the subsequent drying step, it is preferable to dry to the touch at room temperature and then heat dry. The heat drying is generally carried out at 30 to 200° C. for 5 to 120 minutes, either stationary or under ventilation.

Here, we will describe a general method for preparing a coating solution, taking as an example the case where the charge transport layer corresponds to the surface layer of the photoreceptor and a lubricant powder is added to it. Then add the lubricant powder and disperse it evenly. As a dispersion method, a homogenizer, an ultrasonic wave, a male mill, a vibrating Seel mill, a sand mill, an attritor, a roll mill, etc. may be used. In addition, in order to improve the dispersibility of the lubricant powder, a known dispersant can be added. After dispersing the lubricant powder in this manner, a suitable amount of this dispersion is further mixed with a solution containing a charge transport substance and an acetylacetone metal complex to obtain a coating liquid.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

The oxidation potential in the examples was determined by using a saturated Romeril solution as the electrolyte, sweeping the entire potential of the working electrode with a potential sweeper, and using the peak position of the obtained current-potential curve as the value of the oxidation potential. Next. For details, let the sample be 0, I N (n − Bu ) NC
5-10 mmol in the electrolyte of IO4 acetonitrile solution
Dissolve to a concentration of about 1%.

Then, apply this sample solution vc IL pressure, measure the current change when changing the voltage linearly from a low potential,
Obtain the current-potential curve. The potential value corresponding to the first inflection point of the current value in this current-potential curve was defined as the oxidation potential in the present invention.

Example 1 An aluminum cylinder of 80φ x 360m was prepared as a conductive support.

On the other hand, 100 parts (by weight, hereinafter the same) of conductive powder coated with 75fii1% of tin oxide total titanium oxide containing 101i mass% of antimony oxide, 100 parts of resol-based phenol fat, and methanol In addition to a solution consisting of 30 parts and 1100 parts of methyl serotonin, the mixture was well dispersed using a Gale mill to obtain a paint. This coating material was dip-coated onto the above-mentioned conductive support and thermally cured at 140° C. for 30 minutes to form a conductive undercoat layer having a thickness of 20 μm.

On top of this, 1 part of polyamide resin (6-66-610-12 quaternary nylon copolymer) and 8-nylo yw + fat (methoxymethylated 6 nylon methoxylation rate approximately 30%)
) 3 parts to 30 parts of methanol! A coating solution dissolved in a solvent consisting of 40 parts of tanol was applied using the V method, and after drying at 70° C. for 10 minutes, a 0.5 μm thick undercoat layer was formed.

Next, 10 parts of bisazo pigment of the following structural formula (2), 5 parts of polyvinyl butyral resin, and 77,100 parts of cyclohexane were dispersed for 20 hours in a sand mill apparatus using 1φ diameter beads. Add 50 to 100 (appropriate) parts of tetrahydrofuran to this dispersion, apply it on the undercoat layer, and dry for 5 minutes at 100°C.
．． A charge generation layer with a thickness of 12 μm was formed.

Next, a hydrazone compound [oxidation potential 0.57 V (abbreviation CT-1)] of the following structural formula (3) as a charge transport substance, zinc acetylacetonate of the following structural formula (4) as an acetylacetone metal complex, and a binder. A bisphenol A precargonate resin was prepared. First, 20 parts of a polycargonate resin, 20 parts of a charge transport material of structural formula (3), and 1 part of zinc acetylacetonate (abbreviated as AAM-1) of structural formula (4) were added to 100 parts of monochlorobenzene, and then dichloroethane was added. A coating solution was prepared by dispensing 20 parts. This coating solution was applied onto the charge generation layer and dried with hot air at 100° C. for 90 minutes to form a charge transport layer with a thickness of 20 μm.

The thus obtained photoreceptor was used in a modified copying machine (product name NP-35) in which the developer and cleaner unit were removed.
25. It was mounted on a Canon Co., Ltd., and the charging and exposure processes were repeated 10,000 times.

Immediately after that, a copy was made using a copying machine (described above) and the image was observed, but no image blurring occurred and a high-quality image could be obtained.

Furthermore, this photoreceptor was subjected to a durability test of 5,000 images in a copying machine (see above), and after being left in the copying machine for 3 days, 97 images were clear and of high quality after being left in the copying machine for 3 days. No white spots were observed even in the position corresponding to the part close to the medium strain TI5.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that zinc acetylacetonate was not added, and the same tests were conducted.

Image picketing occurred over the entire surface of the image, making it impossible to distinguish the characters.

However, there is a white void V' at a position corresponding to the part close to the charger.
iu was not praised.

Examples 2 to 15 Compound of CT-1 as charge transport material, oxidation potential 0
．． A compound of structural formula (5) (abbreviated as CT-2) of 54, a compound of structural formula (6) (abbreviated as CT-3) with oxidation potential of 0.47, and a compound of structural formula (6) (abbreviated as CT-3) with oxidation potential of 0.47. A photoreceptor manufactured in the same manner as in Example 1 using the compounds shown in Table 1 was subjected to the same tests for the same tolerance. The results are summarized in Clone 2.

Examples 16 to 20 Using the compound CT-1 as the charge transport material and the compound AAM-1 as the acetylacetone metal complex, the photoreceptor was prepared in the same manner as in Example 1 except for changing the amount of the latter added. Table 2 shows the results of the evaluation.

Comparative Examples 2 to 8 Photoreceptors were separated and evaluated in the same manner as in Example 1, using CT-2 and CT-3 as the charge transport materials and without adding the acetylacetone metal complex.

Further, a photoreceptor was manufactured and evaluated in the same manner as in Example 1, using CT-1 as the charge transport material and adding 0.0331 tt% and 22% by weight of AAM-1 as the acetylacetone metal complex.

Furthermore, a photoreceptor using a charge transporting material having an oxidation potential of 0.6 V or higher shown in Table 3 (no acetylacetone gold scrap complex added) was manufactured in the same manner as in Example 1 and evaluated.

The results are summarized in Table 4.

Table 3 Example 21 In addition to the charge transport material, AAM-1, and polycarbonate resin used in Example 1, tetrafluoroethylene resin powder and a fluorine-based acrylic oligomer as a dispersant were prepared.

First, 20 parts of polycargonate resin, 2 parts of hydrazone compound
0 parts and 0.6 parts of fluorine-based acrylic oligomer are dissolved in 100 parts of monochlorobenzene.

Next, 6 parts of tetrafluoroethylene resin powder was processed into this,
Dispersed for 40 hours in a stainless steel Yumeru mill, and further M-tone.
Added 11 parts of dichloromethane solution to 20 parts of metal,
The coating liquid was t-Sa. This coating solution was applied onto the charge generation layer and dried with hot air at 100° C. for 90 minutes to form a charge transport layer with a thickness of 20 μm.

The photoreceptor manufactured in this way has a grade penetration amount of 1.1 mm, a relative speed of the sponge roller of 102%, and a glue IJ =
Modified to have a locking mechanism 7? I attached it to a copying machine (mentioned above) and evaluated its durability, and even after 10,000 copies, no blurring occurred and I was able to obtain high-quality copies. The amount of decrease in the film thickness of the photoreceptor at this time was 1.5 μm. Furthermore, this photoreceptor was left in a copying machine for three days and then copied, and the image was clear and of high quality, and no white spots were observed even in the areas close to the electric distortion device during the time of storage. Ta.

Examples 22 to 29 As lubricant powder, polytetrafluoroethylene resin powder, polyfluorinated pinylene resin powder, difluoride dichloride ethylene resin powder, polyethylene powder, polypropylene powder, cardene fluoride, and AAM 1 to 5 using the compounds of CT-1 to 3 as acetylacetone metal complexes as charge transport substances
A photoreceptor was produced and evaluated in the same manner as in Example 21 using the compound. The results are shown in Table 5.

As mentioned above, the photoreceptor manufactured by adding all the acetylacetone metal complex to the charge transport material with an oxidation potential of less than Q, 6V has no deterioration of the charge transport material, no blurring of the image, and always has a high This allows you to obtain high-quality images. Further, even if the copying machine is left in a copying machine for a long period of time, white spots corresponding to the portions close to the charger do not occur, and high-quality images are always obtained.

Further, by adding all kinds of lubricant powders, high-quality images can always be obtained even after 10,000 sheets of printing, and a highly durable photoreceptor has been realized.

Example 30 In the same manner as in Example 1, an undercoat layer was formed on the support of an 80φ cylinder. Next, the following hydrazone compound (
CT-1) Part 15, Polycar? 10 parts of natez resin was dissolved in 50 parts of dichloromethane and 10 parts of monochlorobenzene, and the solution was applied onto the undercoat layer to form a charge transport layer with a thickness of 15 μm.

Next, 4 parts of a disazo pigment having the following structural formula, 10 parts of polycargenate z resin, and 50 parts of cyclohexanone were dispersed for 20 hours in a sand mill using a 1φ diameter bead. (Charge generation layer dispersion ■) Next, 4 parts of hydrazone compound (CT-1), polycarbonate) Zl (10 parts of fat and 10 parts of dichloromethane).

A charge transport layer solution (2) was prepared by dissolving in 40 parts of monochlorobenzene and further adding 0.3 parts of zinc acetylacetonate. The above charge generation layer dispersion ■ and charge transport layer liquid ■
A photoreceptor was manufactured by mixing the above to prepare a coating material, coating it on the charge transport layer, and molding the charge generation layer to a thickness of 5 μm.

The copying machine used in Example 1 was modified so that it could be positively charged, and this photoreceptor was evaluated in the same manner as in Example 1.

There was no blurring in the images after 10,000 cycles, and it was possible to obtain high-quality images. Also, the image after being left in the copying machine is clear and there are no white spots.

Comparative Example 9 Comparison to Example 30 A photoreceptor was produced in the same manner as in Example 30 except that zinc acetylacetonate was not added at all, and the same evaluation was conducted. Image blur occurred over the entire image, making it impossible to distinguish the characters.

〔Effect of the invention〕

As described above, the electrophotographic photoreceptor of the present invention containing a charge transport substance with an oxidation potential of less than 0.6 V and an acetylacetone metal complex has extremely high durability in a corona discharge environment, and does not cause image blurring or white spots. , the increase in residual potential is also suppressed, and stable, high-quality images can be obtained at all times.

Furthermore, in combination with various lubricant powders, mechanical durability is improved, and a highly durable electrophotographic photoreceptor can be obtained.

Claims (8)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive support, at least the surface layer contains a charge transport substance with an oxidation potential of less than 0.6 V and an acetylacetone metal complex represented by the following general formula (1). An electrophotographic photoreceptor characterized by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (However, in the above formula, M is a metal atom and n is an integer from 1 to 4) (2) The electrophotographic photoreceptor according to claim 1, wherein the surface layer contains lubricant powder. (3) The electrophotography according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, and the charge transport layer is coated on the charge generation layer. Photoreceptor. (4) Electrophotography according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, and the charge generation layer is coated on the charge transport layer. Photoreceptor. (5) The electrophotography according to claim 1, wherein the photosensitive layer is a single layer containing a charge-generating substance and a charge-transporting substance. Photoreceptor. (6) The electrophotographic photoreceptor according to claim 1, wherein the amount of the acetylacetone metal complex added to the surface layer is 0.05 to 20.0% by weight. (7) The electrophotographic photoreceptor according to claim 2, wherein the lubricant powder is selected from fluororesin powder, polyolefin resin powder, and fluorocarbon powder. (8) The amount of the lubricant powder added to the surface layer is 0.
The electrophotographic photoreceptor according to claim 2, wherein the content is 5 to 50% by weight.