JPH01285949A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a image having high quality contg. no undistinct image nor white spots by incorporating at least one kind of charge transfer material having <0.6V oxidation potential and a specified metal salt of a fatty acid into a surface layer. CONSTITUTION:At least one kind of charge transfer material having <0.6V oxidation potential and a metal salt of fatty acid expressed by the formula I are incorporated into at least a surface layer. Suitable charge transfer material to be used having <0.6V oxidation potential is a hydrazone compd., stilbene compd., etc., which may be used in combination of >=2 kinds thereof. Further, suitable amt. of the metal salt of fatty acid to be added is 0.05-20.0% expressed in terms of wt.% in the surface layer of the photosensitive body. Thus, a image having high quality contg. no undistinct image nor white spot is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an electrophotographic photosensitive material that can be widely used in electrophotographic application fields such as electrophotographic copying machines, laser beam printers, CRT printers, and electrophotographic plate making systems. Regarding the body. More specifically, the present invention relates to an electrophotographic photoreceptor having high sensitivity and excellent durability.

[Conventional technology]

In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoconductors (hereinafter referred to as photoconductors), and in particular, functionally separated photoconductors in which a charge generation layer and a charge transport layer are laminated are already in practical use. It is now installed in copiers and printers. However, one major drawback of these photoreceptors has been that they generally have low durability. Durability is broadly divided into durability of electrophotographic physical properties such as sensitivity, residual potential, charging ability, and image density, and mechanical durability such as abrasion and scratches on the photoreceptor surface due to rubbing.

The low durability of the former is due to deterioration of the charge transport material contained in the photoreceptor surface layer due to ozone, NOx, etc. generated from the corona charger. Particularly when the oxidation potential of the charge transport material is less than 0.6V, this deterioration is significant, and as it is used for long periods of time, images become distorted and characters become indistinguishable.
A phenomenon called so-called image distortion occurs noticeably. 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 efforts have been made to improve mechanical durability by dispersing various lubricants on the surface of photoreceptors, the amount of abrasion has decreased significantly, and it has become impossible to promptly remove deteriorated charge transport materials. Currently, the occurrence of image picketing is becoming more apparent.

The present inventors have found that it is effective to use a compound with an oxidation potential of 0.6 V or more as a charge transport substance contained in the surface layer as a solution to these problems, and have put this into practical use in highly durable photoreceptors. However, new problems have been pointed out depending on how the photoreceptor is used. In other words, if a photoconductor is left in a copying machine for a long period of time after being used continuously, a phenomenon occurs in which the charging ability of the photoconductor in the vicinity of the charger that performs corona discharge is apparently reduced, causing white spots to appear on the image. This is the appearance of streaks, so-called white spots. This phenomenon of white spots is a peculiar phenomenon that occurs when a charge transport material with an oxidation potential of 0.6V or more is used.
This is not seen at all in charge transport materials with low oxidation potentials below 0.6V.

The above-mentioned image blur and white spots are caused by ozone and NOx generated during corona discharge, and if the oxidation potential of the charge transport material is less than 0.6V, it will itself generate ozone on the photoreceptor surface. When the oxidation potential is 0.0.
Charge transport materials with voltages of 6V or higher are not easily susceptible to oxidation, so ozone and NOx penetrate into the deep layer 1 of the photoreceptor and oxidize the charge generating material, lowering its resistance and promoting hole injection from the substrate. Therefore, it is presumed that the apparent upper potential does not appear and a white-out phenomenon occurs. This observation shows that the above potential drop occurs even during durable use, but because the drop in surface potential occurs uniformly on the surface of the photoconductor, it is considered to be a white-out phenomenon, which is a partial potential drop. is not observed, and when the battery is left after continuous use, a local potential drop becomes noticeable in the form of white spots in the vicinity of the charger where the K, ozone, or NOx concentrations are extremely high.

[Problems to be solved by the present invention]

An object of the present invention is to provide a photoreceptor that can produce high-quality images without image defects or white spots. Another object of the present invention is to provide a highly durable photoreceptor that is less prone to surface wear and scratches due to rubbing and is capable of producing high quality images. A further object of the present invention is to provide a photoreceptor that does not accumulate residual potential in an electrophotographic process that is performed repeatedly and that consistently produces images of high quality.
be.

[Means for Solving the Problems] As a result of extensive studies in accordance with the above objectives, the present inventors found that even in photoreceptors using charge transport materials with an oxidation potential of less than 0.6V, a specific organic compound may be added. Kinoe qAK has discovered that it is possible to obtain a photoreceptor that does not cause image blurring by preventing its deterioration.

That is, the present invention provides a photoreceptor having a photosensitive layer on a conductive substrate, in which at least one layer of a charge transport material having an oxidation potential of less than 0.6 V is added to at least the layer furthest from the conductive substrate, the surface layer. The percentage indicates that the fatty acid metal salt represented by Formation (1) below is contained.

The purpose of adding the fatty acid metal salt in the present invention is to protect the charge transport substance from the oxidizing effects of ozone and NOx. In other words, it has been found that the fatty acid metal salts described below are preferentially subjected to the acidic effects of ozone and NOx over charge transport substances, and that their oxidized deterioration products do not have any adverse effects on other electrophotographic properties. .

In addition, since the photoreceptor of the present invention does not suffer from deterioration of the charge transport substance, mechanical durability (reduction in the amount of abrasion of the surface layer due to continuous use) can be improved by adding various lubricant powders.

The present invention will be explained in 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. Namely.

The photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer,
In addition, the charge generation layer is coated on the charge transport layer, or, conversely, the charge transport layer is coated on the charge generation layer. Of these, the latter is preferred.

The charge generating substances used in the present invention include biryllium, thiopyrylium dyes, phthalocyanine pigments, anthoanthrone pigments, perylene pigments, dibenzpyrenequinone pigments, pyranthrone pigments, triazo pigments, disazo pigments,
Examples include azo pigments, indigo pigments, and quinacridone pigments, and two or more of these can also be used in combination.

The amount used is generally in the range of charge generating substance/binder = I10 to 1/20, preferably in the range of 4/1 to 1/10, based on the weight of the binder.

The thickness of the charge generation layer is appropriately selected from a range of 0.05 to 60 .mu.m as necessary.

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 polyarylalkane, and two or more of these can be used in combination.

The amount of charge transport material used is generally in the range of charge transport material/binder = 3/10 to 20/10, preferably in the range of 5/10 to 15/10, based on the weight of the binder.

Further, the thickness of the charge transport layer is generally in the range of 10 to 40 microns, preferably in the range of 15 to 30 microns.

Note that since the charge transport substance generally has a low molecular weight, it cannot be formed into a film by itself. Therefore, it is necessary to use a resin with film-forming properties as a binder.

Preferably, K is polymethacrylic acid ester, polycarbonate, polyarylate, polyester, polysulfone, etc., since it has a certain degree of hardness even when used alone and does not interfere with carrier transport.

Next, the fatty acid metal salt used in the present invention has the following general formula (
I).

(CITIHn+1COO+nM(■) However, in the formula y
is a metal atom such as Zn, Cu, Mg, At, Ca, Fe, Ni, etc. Among these, Zn, Mg, At
, Fe, and Ca are preferred. m is an integer of 10 to 31, preferably 15 to 19. n is an integer from 1 to 3. In the present invention, metal stearates with m of 17 are preferred.

The amount of the fatty acid metal salt added is suitably 0.05 to 20.0 inches, preferably 01 to 10.0 inches, as a weight fraction in the surface layer of the photoreceptor.

If the amount added is less than 0.05%, the effect of preventing image blurring on the photoreceptor will not be sufficient, and if it exceeds 20 inches, the residual potential will increase (capri on the image).

When manufacturing the photoreceptor of the present invention, the conductive substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, and indium. , gold, platinum, etc.Although the substrate itself is not conductive, it has a conductive layer on one side or inside, such as aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. Examples include glasstic with a film formed by a vapor deposition method, plastic with a film formed with carbon black or silver particles together with a suitable binder, paper or plastic impregnated with a conductive substance, glasstic with a conductive f-rimer, etc. Furthermore, it is also possible to use a binder coated with a dye in which metal powder such as copper or aluminum or powder such as carbon black, tin oxide, antimony oxide, or titanium oxide is dispersed on the substrate. are phenolic resin, urethane resin, epoxy resin,
Mention may be made of phenoxy resins, polyvinyl alcohol, acrylic resins, and polyamides.

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 substrate and the photosensitive layer. This subbing layer contains casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin,
It can be formed from K such as polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is generally 01 to 4.
0 micron, preferably 0.3 to 3 micron is suitable.

The lubricant powder used in the present invention includes fluororesin powder, polyolefin resin powder, and fluorocarbon powder, and two or more of these can also be used in combination. Fluorine-based resin powders include tetrafluoroethylene resin, trifluorochloroethylene resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoroethylene chloride, and copolymer resins of these. Examples of the polyolefin resin powder include powders of polyethylene, polypropylene, and copolymer resins thereof.

The content of lubricant powder in the surface layer of the photoreceptor of the present invention is 0.
．． A range of 5 to 50% by weight is preferred. Its content is 05
If the weight is less than -, the mechanical durability of the photoreceptor will not be sufficient, and if it exceeds 50 weight, the light transmittance and carrier mobility will be lowered, which is not preferable.

On the other hand, the photosensitive layer can be coated on the conductive substrate by dip coating method, souffle coating method, spinner coating method, bead coach ink method, Mayer-Per coating method, blade coating method, roller coating method, curtain coating method. This can be done using a coating method such as. In the subsequent drying step, it is preferable to dry to the touch at room temperature and then heat dry. The heat drying is 5 to 1 at 30 to 200℃.
It is common to do this for 20 minutes, either still or with 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 photoreceptor13) and a lubricant powder is added to it. First, the binder is mixed with a suitable solvent. After dissolving the lubricant powder, add the lubricant powder and disperse it evenly. This dispersion method includes homogenizer, ultrasonic,
Goalmill, vibration +4? - Lumill, sand mill, attritor, 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 coating liquid is obtained by further mixing an appropriate amount of this dispersion liquid with a solution containing a charge transport substance and an acetylacetone metal complex.

〔Example〕

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

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

On the other hand, a conductive powder was prepared by coating titanium oxide with tin oxide containing 10 parts by weight of antimony oxide, and 100 parts (parts by weight, same hereinafter) of the titanium oxide were coated with tin oxide containing 10 parts by weight of antimony oxide. 100 parts of phenolic resin and 3 parts of methanol
In addition to a solution consisting of 0 parts and 1100 parts of methylcelonol,
It was well dispersed using a gall mill device and made into a paint. This paint was dip coated onto the conductive substrate and cured by heating at 140° C. for 30 minutes to form a conductive undercoat layer with a thickness of 20 μm.

Subsequently, this upper K, polyamide resin (6-66-6
1 part of 10-12 quaternary nylon copolymer) and 3 parts of 8-nylon resin (methoxymethylated 6 nylon methoxylation rate of about 3 os) were dissolved in a solvent consisting of 30 parts of methanol and 40 parts of butanol, and immersed in a coating solution. Apply by method, 7
It was dried at 0° C. for 10 minutes to form a 0.5 μm thick undercoat layer.

Next, 10 parts of a bisazo pigment having the following structural formula (n), 5 parts of polyvinyl butyral resin, and 100 parts of cyclohexanone were dispersed for 20 hours using a sand mill apparatus using 1φ glass beads. Add 50 to 100% of tetrahydrofuran to this dispersion.
(appropriate) was applied onto the undercoat layer and dried at 100° C. for 5 minutes to form a charge generating layer with a thickness of 0.12 μm.

Next, a hydrazone compound of the following structural formula (I[l) [oxidation potential 0.57 V (abbreviation CT-1)] was used as a charge transport material.
And zinc stearate as a fatty acid metal salt, and bisphenol A type number as a binder? A licargenate resin was prepared.

First, 20 parts of bisphenol A type polycarbonate resin, 20 parts of a charge transport material of structural formula (III), and 1 part of zinc stearate (abbreviated as FAM-1) are added to 100 parts of monochlorobenzene, and then 20 parts of dichloroethane is added and coated. A liquid was prepared. 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, manufactured by Canon ■) and charged.

The exposure process was repeated 10,000 times. Immediately after that,
Copies were made using a copying machine (described above) and images were observed, but no image blurring occurred and a high-quality image could be obtained.

Furthermore, this photoconductor was processed by a copying machine (mentioned above) at a rate of 500
After running a 0-sheet image printing test and leaving it in the copying machine for 3 days, copies were made. The image was clear and of high quality, and no white spots were observed even in positions corresponding to areas close to the abandoned electrical appliance.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that the zinc stearate used in Example 1 was not added, and the same tests were conducted. The image was blurred over the entire surface, making it impossible to distinguish the characters. However, no white spots were observed at positions corresponding to areas close to the charger.

Examples 2 to 15 As a charge transport substance, the compound of CT-1, a compound of structural formula (■) with an oxidation potential of 0.54 (abbreviation CT-2), and a compound of the structural formula (■) with an oxidation potential of 0.47 (abbreviation) The photoreceptor was manufactured in the same manner as in Example 1 (]8) using the compound CT-3) and the compound shown in Table 1 of the FAM-1 compound as the fatty acid metal salt. We conducted an evaluation. The results are shown in Table 2.

Examples 16 to 20 Using the compound of CT-1 and the compound of FAM-1,
A photoreceptor was produced and evaluated in the same manner as in Example 1, except that the amount of the latter added was varied. The results are shown in Table 2.

Table 1 *Saturated calomel electrode is the reference electrode.

Φ e O, I N(n-Bu)4NclD4 acetone solution was used as an electrolyte, the potential of the working electrode was swept with a potenzoyarsuino, and the peak position of the obtained current-potential curve was directly adjusted to the oxidation potential. It was calculated as a value.

Comparative Examples 2 to 8 Photoreceptors were produced and evaluated in the same manner as in Example 1, using the CT-2 compound and CT-3 compound as charge transport materials and without adding fatty acid metal salts. Using the compound CT-1 as a charge transport material, zinc stearate (FAM-1) was added at 0.03% by weight and 22% by weight.
A photoreceptor containing % by weight was produced in the same manner as in Example 1,
evaluated.

Furthermore, a photoreceptor (without addition of fatty acid metal salts) using the above charge transport material with an oxidation potential of 0.6vy shown in Table 3 was used as an example]
It was manufactured and evaluated in the same manner.

The results are summarized in Table 4.

Sac 3 Example 21 The charge transport substance used in Example 1, zinc stearate, and bisphenol A type polycarbonate? In addition to the ester resin, polytetrafluoroethylene resin powder and a fluorine-based acrylic oligomer were prepared as a dispersant.

First, 20 parts of bisphenol A type polydenate resin, 20 parts of hydrazone compound, and 0.6 part of fluorine-based acrylic olidemer are dissolved in 100 parts of monochlorobenzene. Next, add 6 parts of polytetrafluoroethylene resin powder to this and make stainless steel? - Dichloromethane solution dispersed for 40 hours with Zinc Stearate and added with Zinc Stearate 20
A coating solution was prepared. This coating solution was coated on the charge generation layer and dried with hot air at 100°C for 90 minutes.
A charge transport layer with a thickness of 0 μm was formed.

The photoreceptor manufactured in this way had a blade penetration depth of 1.1 m.
A copying machine (see above) K modified to have a sponge roller cleaning mechanism with a relative speed of 102 inches was installed, and its durability was evaluated. No blurring occurred even after 10,000 sheets of use, and the image quality was high. The amount of copies was 1.5μ. Furthermore, this photoconductor was left in a copying machine for three days and then copied, and the resulting image was clear and of high quality, and no white spots were observed in the positions corresponding to the areas close to the charger while the photoconductor was left unused. Ta.

Examples 22 to 29 As lubricant powder, polytetrafluoroethylene resin powder, polyvinylidene fluoride resin powder, polynifluorodichloride ethylene resin powder, JIJ ethylene powder, polyglobylene powder, fluorinated carbon, Moreover, the above-mentioned CT is used as a charge transport material.
- Compounds 1 to 3 are SAM as stearic acid metal salts.
Photoreceptors were produced in the same manner as in Example 21 using each of Compounds I to 5, and evaluated. The results are shown in Table 5.

As can be seen from Table 5, photoreceptors manufactured by adding metal stearate to a charge transport material with an oxidation potential of less than 0.6 V do not suffer from image blurring due to no deterioration of the charge transport material, and are always high. A quality image can be obtained. Furthermore, even if the copying machine is left in the copying machine for a long period of time, white spots corresponding to the areas close to the charger do not occur, and high-quality images are always obtained.

Furthermore, those to which various lubricant powders are added realize highly durable photoreceptors, and can always obtain high-quality images even after being used for 10,000 sheets.

Example 30 As in Example 1, an undercoat layer was formed on an 80φ aluminum cylinder substrate. Next, a solution prepared by dissolving 10 parts of the hydrazone compound (CT-1) 15N and hisphenol A type I ricardinate resin used in Example in a mixed solution consisting of 50 parts of sochloromethane and 1 part of monochlorobenzene was applied onto the undercoat layer. A charge transport layer having a thickness of 15 μm was formed.

Next, 4 parts of disazo pigment with the following structural formula and bisphenol A
Polycarbonate resin contains 10 parts of nate resin and 50 parts of cyclohexanone.
The sample was dispersed for 20 hours using a sand mill device using 1φ glass beads. (CG dispersion ■) Next, hydrazone compound (
CT-1) Part 4 and bisphenol humanoid polycarbohydrate
10 parts of CT resin was dissolved in a mixed solution consisting of 10 parts of dichloromethane and 40 parts of monochlorobenceph, and 0.3 parts of zinc stearate was further added to prepare CT solution (2). A paint is prepared by mixing the above C0 dispersion liquid (■) of this CT liquid (■),
A photoreceptor was manufactured by coating this on the charge transport layer described above to form a charge generating Jfk having 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.

The image after being used 10,000 times showed no pickling, and it was possible to obtain an image with good surface quality. I couldn't copy it again.

Comparative Example 9 For comparison with Example 30, a photoreceptor without the addition of zinc stearate was manufactured in the same manner and evaluated in the same manner, but after 10,000 sheets of durable use, image blurring occurred over the entire surface. However, it was impossible to distinguish a single character.

[Effects of the Invention] As is clear from the above, the photoreceptor of the present invention containing a charge transport substance with an oxidation potential of less than 0.6 parts and a fatty acid metal salt has extremely high durability in a corona discharge environment, and has a high resistance to image pickup. With no white spots or residual potential, you can always obtain stable, high-quality images. Furthermore, mechanical durability can be improved by combining with various lubricant powders, and a highly durable photoreceptor can be obtained.

Agent Patent Attorney Ms. Yamashita

Claims (8)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least one type of charge transporting substance having an oxidation potential of less than 0.6 V and a fatty acid metal salt represented by the following general formula (I) in the surface layer An electrophotographic photoreceptor comprising: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (However, in the formula, M is a metal atom, m is an integer from 10 to 31,
n is an integer from 1 to 3. ) (2) The electrophotographic photoreceptor according to claim 1, wherein the surface layer contains one or more lubricant powders. (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 electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer is a single layer containing a charge generating substance and a charge transporting substance. (6) The electrophotographic photoreceptor according to claim 1, wherein the content of the fatty acid metal salt in 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 content of the lubricant powder in the surface layer is 0.
The electrophotographic photoreceptor according to claim 2, wherein the content is 5 to 50% by weight.