JPH01276144A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve durability and to obtain a high-quality image while preventing a pause memory by incorporating a charge transfer material having a specific oxidation potential and the metal salt of specific dialkyl dithiocarbamic acid into the surface layer of the photosensitive body. CONSTITUTION:The charge transfer material having >=0.6V oxidation potential and the metal salt of the dialkyl dithiocarbamic acid expressed by formula (R1, R2 are an alkyl group and M is a metal atom) are incorporated into the surface layer of the photosensitive body having a photosensitive layer on a conductive base body. The resistance to corona products is improved and the electrophotographic characteristics such as sensitivity, residual potential and image blur are stabilized by the use of the charge transfer material having the high oxidation potential. The pause memory of the photosensitive body is effectively prevented by the addition of the metal salt of the dialkyl dithiocarbamic acid. The durability of the photosensitive body is thereby improved and the high-quality image is obtd.

Description

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

[Conventional technology]

In recent years, the development of various organic photoconductive materials has progressed as photoconductive materials for electrophotographic photoconductors, and functionally separated photoconductors in which a charge generation layer and a charge transport layer are laminated on T# have already been put into practical use, and are used in copiers and printers. It is installed in.

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, and chargeability per image, and mechanical durability such as abrasion and scratches on the surface of the photoreceptor due to rubbing. It is known that the low performance 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.

Therefore, as a measure to increase the durability of electrophotographic physical properties,
It is important to use a charge transport material that is not easily degraded by ozone, NOx, etc., and it has been proposed to select a charge transport material with a high oxidation potential. It has become clear that the use of a charge transport material with a high oxidation potential can suppress phenomena such as a decrease in charging ability, an increase in residual potential, and the occurrence of image fading that occur over long-term use, greatly extending the life of the photoreceptor. It has been pointed out that a new problem is that the photoreceptor pause memory phenomenon is more likely to occur. The dormant memory phenomenon is basically a deterioration phenomenon caused by corona products, but after copying is completed, the rotation of the photoreceptor stops, and the charging ability of the part stopped near the corona charger decreases, resulting in In the case of development, the image density is reduced in that part, and in the case of reversal development, the image density increases. This phenomenon tends to occur after the photoreceptor is used for a long period of time, and becomes more noticeable as the life of the photoreceptor is extended by taking the above measures. Improving the intake/exhaust mechanism and the shape of the charger in the main body of the image forming apparatus is a slight improvement, but it is not perfect, and is a problem especially in small copying devices and copying devices with cartridge-type photoreceptors. .

[Problems to be solved by the EIA of this invention] The purpose of the present invention is to have both the durability of the electrophotographic physical properties and the mechanical durability described above, and to improve the performance of the dormant memory when used in an actual image forming apparatus. An object of the present invention is to provide a photoreceptor in which the phenomenon is effectively suppressed.

[Means for solving problems]

The inventors of the present invention have conducted intensive studies to achieve this objective, and have found that in a photoreceptor having a photosensitive layer on a conductive substrate, the layer furthest away from the conductive substrate, that is, the surface layer, has an oxidation potential of 0. .6 V or higher charge transport materials and postscript - Monka (])
a metal salt of soalkyl ditheocarpamate represented by;
Furthermore, it has been found that a photoreceptor that preferably also contains lubricant powder in addition to these materials has the performance that meets the above-mentioned requirements.

That is, in the present invention, the use of a charge transport material with a high oxidation potential of 0.6 V or more improves resistance to corona products and stabilizes electrophotographic physical properties such as sensitivity and residual potential 9 image quality. contributes to

Moreover, the addition of the noalkyldithiolupamic acid metal salt of -Momona (1) has the effect of effectively preventing the dormant memory phenomenon that is more likely to occur due to the use of the above-mentioned charge transporting substance. Furthermore, the addition of lubricant powder, which is preferably used, has the effect of increasing the mechanical durability (surface abrasion resistance) of the photoreceptor and improving its durable life.

The charge transporting substance having an oxidation potential of 0.6v or more used in the present invention includes hydrazone compounds, stilbene compounds,
It is selected from carbazole compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, polyarylalkanes, and the like. Furthermore, the higher the oxidation potential, the better the durability of the photoreceptor, and especially when the oxidation potential is 0.7V or more, the effect becomes more remarkable.

The amount of charge transport material used in the present invention is determined by the binder (
Charge transport material/pine goo-3/
A range of 10 to 20/10 is common, 5/lO to 1
The thickness of the charge transport layer is preferably in the range of 5/10, and the thickness of the charge transport layer is generally in the range of 10 to 40μ, and 5.15 to 30μ.
A range of is preferred.

In addition, when actually coating a photosensitive layer, since the charge transporting substance generally has a low molecular weight, it cannot be formed into a film by itself.

Therefore, for example, in order to form a photosensitive layer in which a charge transport substance is dispersed together with a lubricant powder, which will be described later, a resin having film-forming properties is used as a binder.

As this binder, it has a similar hardness even when used alone, and it does not interfere with carrier replenishment.
Preferred are polymethacrylic esters, polycarbinates, polyarylates, polyesters, polysulfones, and the like.

The dialkyldithiocarbamate metal salt used in the present invention has the following general formula (1).

However, in the above general formula [I], R1 and R2 are alkyl groups which may be different or the same, and are generally methyl, ethyl, n-propyl or the like. M is a metal atom, such as Zn, Nls Pb, CubCr, Co
Examples include. The content of dialkyldithiocarbamate metal salt in the surface layer is suitably 0.05 to 20% by weight, preferably 0.1 to 10.0% by weight. If the content is less than 0.05% by weight, the effect of preventing the dormant memory phenomenon of the photoreceptor will not be sufficient;
Exceeding this results in an increase in residual potential.

The lubricant powder preferably used in the present invention refers to powder of fluorine, thread resin, /lyolefin resin, and carbon fluoride, and two or more of these can also be used in combination. . Furthermore, examples of the fluororesin include tetrafluoroethylene resin, chlorinated ethylene resin, 67. ethylene glopyrene resin, vinyl fluoride resin, vinylidene heptadide resin,
near.

Examples include ethylene dichloride and copolymers thereof; examples of lyolefin resins include polyethylene,
Typical examples include polypropylene and copolymers thereof.

The content of the above-mentioned lubricant powder in the surface layer is 0.5 to
50% by weight is suitable. If the content is less than 0.5% by weight, the mechanical durability of the photoreceptor will not be the same, and the
If it exceeds i%, the light transmittance will decrease and carrier mobility will also decrease, which is not preferable.

In the photoreceptor of the present invention, the photoreceptor layer on the conductive substrate 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 layer, or the charge transport layer is coated on the charge generation layer. Of these, the latter is preferred.

The conductive substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, and molybdenum.

There are materials made of materials such as chromium, titanium, metal, indium, gold, and platinum, and materials that have a conductive layer on the surface or inside even if the substrate itself is not conductive, such as aluminum, aluminum alloy, and oxide. Plastic, which has a layer formed by vacuum deposition of indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., or glass which has a layer formed with a conductive material (e.g. carbon black, silver particles, etc.) together with a suitable binder. Tick,
Paper or glass impregnated with conductive substances, conductive
There are plasti, ri, etc. that have rimers.

An undercoat layer having barrier and adhesive functions can also be provided between the conductive substrate and the photosensitive layer.

This undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-ac+) kW':1 polymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, sulfur 610, copolymerized nylon, alkoxymethylated It can be formed from polyurethane (nylon, etc.), gelatin, aluminum oxide, etc. The thickness of the undercoat layer is usually α1 to 40 microns,
Preferably, a range of α3 to 3 microns is appropriate.

The charge generating substances used in the production of the photoreceptor of the present invention include selenium-tellurium, pyrylium, thiopyrylium dyes, phthalocyanine pigments, aftanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, azo Pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanines, and quinocyanine pigments can also be used in combination of two or more types.

The type of charge generating substance used in the present invention is a binder (
charge generating substance/binder-1 for t:ilK of resin)
The range of 10 to 1/20 is common, and v1 to 1/10
A range of is preferred. In addition, the thickness of the charge generation layer is 0.
．． The thickness is appropriately selected from the range of 05 to 60μ as necessary.

Coating methods such as dip coating, soufflé coating, spinner-coach ink, bead coating, Mayer-per-coating, blade coating, roller coating, and curtain coating are used for coating the photosensitive layer. For drying subsequent to coating, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at 30 to 200° C. for 5 to 120 minutes, either stationary or with air blowing.

The general Y4 manufacturing method for the coating liquid used in the above coating is explained by first dissolving the binder in a suitable bath agent and then dispersing the lubricant powder. For this dispersion, common dispersion means are used: homogenizer, ultrasonic m, &-lumil,
Use a vibrating mail mill, sand mill, attritor, roll mill, etc.

In this dispersion, various known dispersants are appropriately used. On the other hand, a binder, a charge transport substance, and a compound of general formula (1) may be added to a solvent, and an appropriate amount of the above dispersion liquid may be taken and mixed with this solution.

〔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 ξnium clinder was used as a base, and polyamide resin (trade name: Ami 270M-80) was applied to this.
Apply a 5-time methanol solution (manufactured by 00 Toshi) by dipping method,
A 1 μm thick undercoat layer was formed.

Next, 10 parts of the disazo pigment with the following structural formula (parts by weight, the same applies hereinafter), 6 parts of Lipinyl Ptyral resin (black market name: S-LEC BXL, Tanezu Kagaku ((Ten) Ura)) and 100 parts of cyclohexanone were added to lφ glass. The mixture was dispersed for 20 hours using a sand mill device using peas.

Add 50 to 100% of tetrahydrofuran (as appropriate) to this dispersion.
The mixture was coated on the undercoat layer and dried at 100° C. for 5 minutes to form a charge generating layer having a thickness of α15 μm. Next, the compounds shown in Table 1 and zinc noethyldithiocarpamate having the following structural formula were used as charge transport substances.

Bisphenol 2 type polycargonate resin (manufactured by Yutaikasei) was prepared as a binder.

Table 1 *Reference electrode is saturated calomel electrode.

0. Using I N (n-Bu) 4NCJ4 acedol solution as the electrolyte, the potential of the working electrode was swept with a potential sweeper, and the peak position of the obtained current-potential curve was directly determined as the value of the oxidation potential. First, 20 parts of bisphenol-type polycargonate resin, 20 parts of the above charge transport material, and 0.2 parts of the above zinc diethyldithiocarbamate were added to 100 parts of monochlorobenzene, and then 20 parts of dichloroethane was added to form a coating solution of 1 part.
4 were made. This coating liquid was applied onto the charge generation layer, and 1
Hot drying was performed at 00° C. for 90 minutes to form a charge transport layer with a thickness of 20 μm.

For the photoreceptor thus obtained, the amount of grade penetration was 1.
0■, cleaning roller relative speed of 106 inches, a copying machine (part name: NP-3525° manufactured by Canon Co., Ltd.) was installed and a fire resistance evaluation of 100,000 copies was conducted.The results are shown below. Shown in 2.

In Table 2, potential fluctuation is the dark area potential (V
D) is set to -650V, the bright area potential (vL) is set to -150V, and the residual potential (v8) at that time is -iov, and the graph shows the change in absolute value after 100,000 sheets of durable use. be. ``Also, the pause memory is the change in image density between the area immediately below the corona charger and other areas, or the potential (vn
) is expressed as the change in

As can be seen from Table 2, the photoreceptors of Experimental Examples 4 to 8, which used a charge transport material with a high oxidation potential (0.6 V or more) and added zinc diethyldithiocarbamate, showed potential fluctuations even after 100,000 sheets were used. is small, and there is no pause memory.

Example 2 A polyamide resin undercoat layer was formed on an aluminum cylinder under the same conditions as in Example 1 except that the film thickness was 0.5 μm.

Next, 10 parts of a trisazo pigment having the following structural formula, 6 parts of a polyvinyl butyral resin (trade name: S-LEC BL-8, manufactured by Miki Kagaku), and 50 parts of cyclohexane were dispersed in a sand mill apparatus using glass beads. 100 parts of methyl ethyl ketone was added to this dispersion and coated on the undercoat layer to form a charge generation layer with a thickness of 0.2 μm.

Next, a compound with the following structural formula (oxidation potential 0.81) as a charge transport substance, a compound shown in Table 3 as a noalkylnotiorubamate metal salt, and a bisphenol 2 type polycarmenate resin (described above) as a binder were prepared. did.

Thereafter, photoreceptors were manufactured in the same manner as in Example 1 using the compounds listed in Table 3. The amount of each noalkyldithiolupamic acid metal salt added is α2 parts.

Table 4 shows the results of the evaluation of the photoreceptor.The evaluation was carried out using a two-component developer consisting of toner and carrier, equipped with a semiconductor laser with an oscillation wavelength of 780 nm, and equipped with a cleaning blade with a penetration amount of LO■. In Table 4, the potential fluctuation is the dark area potential at the initial stage of durability.
00V, bright area potential at -150V, and residual potential at that time at -10V, and shows the change in absolute value after 100,000 sheets of durable use. Regarding the pause memory, the measurement method is the same as in Example 1, but since reversal development is used, changes in image characteristics appear in the direction of increasing density, contrary to Example 1.

As can be seen from Table 4, the system to which the metal salt of soalkylnotiolupamate is added clearly has the effect of preventing rest memory.

Example 3 A polyamide resin undercoat layer was formed on an aluminum cylinder under the same conditions as in Example 1. Next, add 10 parts of the sosazo pigment of the following structural formula to polyvinyl butyral gruel (trade name: S-LEC BL-
8, 6 parts (Made by Block Chemical), and cyclohexanone sogl
was dispersed using a sand mill device using russian beads. 100 parts of methyl ethyl ketone was added to this dispersion and coated on the undercoat layer to form a charge generating layer 1- with a thickness of α2μ.

Next, prepare a compound with the following structural formula (oxidation potential o, s i ) as a charge transport W material, zinc quethyldithiorupamate with the following structural formula as a dialkyl zothiocarpamate metal, and bisphenol ZW polycarmenate resin (described above) as a binder. did. Thereafter, in the same manner as in Example 1, the amount of zinc zoethyldithiorupamate added was 0.05% by weight of the charge transport layer.

Photoreceptors were manufactured at five levels: 0.1 inch, 1 inch, and 10120 inch.

Table 5 shows the results of evaluating the nine photoreceptors thus obtained in the same manner as in Example 1.

As can be seen from Table 5, the amount of zinc noalkylzotheorubamate added is 0.1 based on the weight of the charge transport layer.
If it is less than 10%, the effect will be small, and if it exceeds 10%, there will be adverse effects such as an increase in residual potential, so the range of 0.1 to 10% is preferable.

Example 4 A subbing layer and a charge generation layer were provided on an aluminum cylinder in the same manner as in Example 1. Thereafter, the compound noalkyldithiolupamate of /165 was used as a charge transport material, and bisphenol 2 type polycarbonate was used as a binder, and tetrafluoroethylene resin (trade name: Luburon L-2.
Daikin Industries''!A) was prepared.

The mass bisphenol type 2 precursor is prepared by dissolving 20 parts of nate resin, 20 parts of the above charge transport substance, and 2 parts of the above iron alpha dialkylzothiocarpamate in 100 parts of monochlorpe/zene, and dispersing it with 6 parts of the above tetrafluoroethylene resin. 15 parts of fluorine-based acrylic oligomer α was added as an agent and dispersed for 50 hours in a stainless steel #i goal mill, and further 20 parts of cyclylmethane was added to prepare a coating solution. 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 obtained photoreceptor was evaluated in the same manner as in Example 1, and the potential fluctuation was ΔVd/Δv・/ΔVm −−207+50/
+30, the rest memory was good at ΔVd-10v, and there was no change in degree over one image. In addition, mechanical durability such as scratches on the surface of the photoreceptor and toner adhesion was also good, and high quality images were obtained even after 100,000 sheets of use.

Example 5 A subbing layer was applied on an aluminum cylinder in the same manner as in Example 1. Next, 15 parts of the /165 hydrazone compound used in Example 1 as a charge transport material and 4 Li-♂
A solution prepared by dissolving 10 parts of nate z-type resin in a mixture of 50 parts of zochloromethane and 10 parts of monochlorobenzea was applied onto the undercoat layer to form a charge transport layer with a thickness of 15 μm. Next, 4 parts of the same disazo pigment used in Example 1, 10 parts of polycarmenate z resin, and 50 parts of cyclohexanone were dispersed for 20 hours using a sand mill device using 1φ glass beads. (CG dispersion ■) Next, 47. Ethylene resin powder, fluorine-based acrylic oligomer as a dispersant, the above hydrazone compound, bisphenol z-ya polycarbonate? nate resin was prepared. First, bisphenol type 2 polycarbon? 10 parts of ester resin, 4 parts of hydrazone compound, and 0.15 parts of fluorine-based acrylic oligomer are dissolved in 10 parts of zochloromethane and 40 parts of monochlorobenzene.

Next, 1.5 parts of tetrafluoroethylene resin powder was added to this and dispersed in a stainless steel gel for 40 hours.Furthermore, 3 parts of magnesium zoethylnotiocarpamate α having the following structural formula was added to this dispersion. CG solution ■ was prepared. A coating material was prepared by mixing this CG dispersion liquid (1) and the above CT liquid (2), and this was coated on the charge transport layer to form a charge generation layer having a thickness of 5 μm to obtain a photoreceptor.

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, but even after 100,000 copies, the potential fluctuation, photoreceptor scraping, and pause memory were all small. A high quality copy was obtained.

Comparative Example 4 For comparison with Example 5, a photoreceptor without magnesium noethyldithiocarpamate was manufactured and the same evaluation was conducted. After 100,000 copies, a pause memory appeared on the image and the potential was ΔVd- -160V.

〔Effect of the invention〕

As is clear from the above, the photoreceptor of the present invention contains a charge transport substance having an oxidation potential of 0.6 parts or more, a dialkyldithiocarbamate metal salt, and more preferably a lubricant powder.
While exhibiting high durability, the pause memory phenomenon is effectively suppressed, making it possible to always obtain stable, high-quality images.

1゛ (Embedded Patent Attorney Johei Yamashita

Claims (8)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least the surface layer contains a charge transporting substance having an oxidation potential of 0.6 V or more and a dialkyldithiocarbamate metal salt represented by the following general formula [I]. An electrophotographic photoreceptor comprising: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In general formula (1), R1 and R2 are alkyl groups that may be the same or different, and M is a metal atom.) (2) The electrophotographic photoreceptor according to claim (1), wherein the surface layer also contains lubricant powder. (3) 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. Electrophotographic photoreceptor. (4) 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. Electrophotographic 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 dialkyldithiocarbamate 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 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.