JPH01283565A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the durability and mechanical durability in terms of electrophotographic characteristics in combination to the electrophotographic body having a photosensitive layer on a conductive base and to obviate the generation of a pause memory by incorporating >=1 kinds of lubricant powders, >=1 kinds of specific charge transfer materials and specific compd. into the layer furthest from the substrate of the above-mentioned photosensitive body. CONSTITUTION:This electrophotographic sensitive body has the photosensitive layer on the conductive substrate and the layer furthest from the substrate of said body contains >=1 kinds of the lubricant powders, >=1 kinds of the charge transfer materials having >=0.6V oxidation potential and the compd. expressed by formula I. The lubricant powders are exemplified by, for example, tetrafluoroethylene resin powder, fluoroplastic powder of a copolymer of monomers constituting said polymer, etc. The charge transfer materials having >=0.6V oxidation potential are exemplified by, for example, a hydrazone compd., etc. The durability and mechanical durability in terms of electrophotographic characteristics are thereby improved and further, the pause memory of the photosensitive body is extremely suppressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a highly sensitive and durable product that is widely used in electrophotographic application fields such as 1M1 child photocopiers, laser beam printers, CRT printers, and electrophotographic plate making systems. This invention relates to an excellent electrophotographic photoreceptor.

[Prior Art] In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoreceptors, and these organic photoconductive materials have already been developed.
Among the photoreceptors using Monoga, a functionally separated type in which a charge generation layer and a charge transport layer are laminated has been put into practical use and is installed in copying machines and printers.

However, these photoreceptors generally have poor durability against electrophotographic characteristics such as decreased sensitivity, fluctuations in residual potential, decreased charging ability, image blurring, and abrasion due to rubbing on the surface of the photoreceptor.
The lifespan of these photoreceptors was unsatisfactory because of their poor mechanical durability against scratches and the like.

It is known that the cause of poor durability of the electrophotographic characteristic surface, especially the cause of image blurring, is the deterioration of the charge transport material in the photoreceptor surface layer due to ozone, NO, etc. generated from the corona charger. In order to improve the durability of characteristics,
Substances with high oxidation potential are known as charge transport substances that are not easily degraded by ozone, NO, 1, etc.

It is known that the cause of poor mechanical durability is that paper, cleaning members such as blades and rollers, toner, etc. contact and rub against the surface of the photosensitive layer. , provides good lubricity on the surface of the photoreceptor.
Fluororesin and fluorine are added as additives to the surface layer, which can reduce friction and make the surface resistant to rubbing, improve releasability, and prevent toner filming, fusion, etc. Sliding materials such as carbonized graphite and polyolefin resin have been proposed (Japanese Patent Application Laid-open Nos. 56-25746 and 56-257).
No. 49, No. 61-123850).

Furthermore, it has been proposed to apply a combination of techniques for improving the durability of electrophotographic properties and mechanical durability (
According to this technique, the life of the photoreceptor can be considerably extended.

[Problems to be Solved by the Invention] However, it has been pointed out that the above-mentioned technique causes a new problem in that photoreceptor pause memory development is more likely to occur. The dormant memory phenomenon is basically a phenomenon of deterioration due to corona generation and objects, but after copying is completed, the rotation of the photoreceptor stops and the charging ability of the portion of the photoreceptor that is stopped near the corona charger increases. This is a phenomenon in which the image density decreases in that area in the case of normal development, and increases in the image density in the case of reversal development.

This phenomenon tends to occur after using the photoreceptor for a long period of time, and the above improvements will make it more noticeable as the life of the photoreceptor is extended. As a result, a slight improvement in the pause memory can be seen, but it is not perfect, and this poses a problem, particularly in small-sized copying machines and copying machines a having cartridge-type photoreceptors.

Therefore, an object of the present invention is to provide a photoreceptor that has both durability in terms of electrophotographic properties and mechanical durability, and does not cause the dormant memory phenomenon when used in an actual image forming bag. .

[Means for Solving the Problems] The problem is that in an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least the layer furthest from the substrate,
Solved by an electrophotographic photoreceptor characterized by containing one or more lubricant powders, one or more charge transport substances having an oxidation potential of 0.6 V or more, and a compound represented by the following general formula (1). It was done.

General formula (1) % Formula % is an alkyl group having a prime number of 1 to 10 or an alkenyl group having a carbon number of 2 to 10] In the present invention, the addition of (j) lubricant powder improves the slipperiness and wear resistance of the surface layer. (ii) Oxidation potential 0.6
The use of a charge transport material with a high oxidation potential of V or more improves durability against corona products and contributes to stabilizing electrophotographic properties such as sensitivity, residual potential, and image blur. (
iii) Furthermore, the compound of the general formula (1) is (i), (i
Since the life of the photoreceptor is extended by means i), it has the effect of preventing the photoreceptor stop memory phenomenon from occurring again.

Examples of the lubricant powder used in the present invention include tetrafluoroethylene resin powder, trifluorochloroethylene resin powder, hexafluoroethylene propylene resin powder, difluoride dichloride ethylene resin powder, and fluoride ethylene resin powder. Fluorine resin powders such as vinylidene resin powders and copolymers of the monomers that make up these bombers: polyethylene resin powders, polypropylene resin powders, polyhexene resin powders, and copolymers of the monomers that make up these polymers. Examples include polyolefin resin powder such as polymer; fluorocarbon powder.

Examples of charge transport substances with an oxidation potential of 0.6 V or more used in the present invention include hydrazone compounds, stilbene compounds, carbazole compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, Examples include aryl alkanes. The higher the oxidation potential of the charge transport material, the better the durability of the photoreceptor, and when the oxidation potential is 0.7 V or higher, the effect becomes more pronounced.

Charge transport materials generally have a low molecular weight and cannot be used to form a film by themselves, so a resin having film-forming properties is used as a binder to form a photosensitive layer in which the lubricant powder is dispersed.

The binder resin is not particularly limited as long as it is a polymeric compound with film-forming properties, but from the viewpoints of having some degree of hardness even when used alone and not interfering with carrier transport, the number of binder resins, polymethacrylate ester, polycarbonate, polyarylate, etc. , polyester, polysulfone, etc. are preferred.

The binder resin contained in the layer farthest from the substrate is usually 50 to 3 parts by weight per 100 parts by weight of the charge transport material.
About 0.00 parts by weight is used.

The content of the lubricant powder dispersed in the layer farthest from the substrate is based on the total amount of the charge transport substance and the binder (if the core layer contains a charge generation substance, the generated ha). 1.0-30ffi amount% is appropriate, especially 2.
0 to 20% is preferred.

If the content is less than 1.0% by weight, the surface modification effect due to dispersion of the lubricant powder will not be sufficient, while if it exceeds 30% by weight, the light transmittance will decrease and carrier mobility will also tend to decrease. be.

Examples of the compound represented by the general formula (1) used in the present invention include the following compounds.

The content of the compound represented by the general formula (1) contained in the layer farthest from the substrate is the same as that of the charge transport substance (if the core layer contains a charge generation substance, the charge generation substance).
The amount is usually 0.1 to 30% by weight, particularly preferably 0.2 to 10% by weight, based on the total amount of binder. When the amount added is less than 0.1% by weight, the effect of preventing sleep memory is insufficient, and when it exceeds 30% by weight, the residual potential tends to increase.

When producing the electrophotographic photoreceptor of the present invention, the substrate may be the substrate itself or a conductive material such as aluminum,
Aluminum alloy, copper, zinc, stainless steel, vanadium, mosopden, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, and in addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy Substrates made of plastics (e.g. carbon black, silver particles, etc.) coated on plastics with a suitable binder by vacuum deposition, substrates made of plastic or paper impregnated with conductive particles, and conductive materials. Plastics containing polymers, etc. can be used.

A subbing layer having a barrier function and an adhesive function can also be provided between the conductive layer and the light absorbing layer. The subbing layer is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610° copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0.1 micron to 40 micron.

Preferably, 0.3 micron to 3 micron is suitable.

Charge-generating substances include selenium-tellurium, biryllium, thiobililicum dyes, phthalocyanine pigments, anthanthrone pigments, dibenzpyrenequinone pigments, and lanthrone pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, and asymmetric quinocyanine. , quinocyanine, etc. can be used.

As a method for dispersing the lubricant powder, conventional dispersion means such as a homogenizer, an ultrasonic wave, a ball mill, a vibration mill, a sand mill, an attritor, a roll mill, etc. can be used. After adding the lubricant powder to the binder dissolved in a suitable solvent, it is dispersed by the above-mentioned dispersion method. A surface layer coating liquid containing lubricant powder can be obtained by mixing an appropriate amount of this with a solution in which a binder, a charge transport substance, and a compound not represented by the general formula (1) are dissolved in an appropriate solvent.

Construction methods include dip coating method, spray coating method, spinner coating method, beat coating method,
Meyer par coating method, blade coating method,
This can be carried out using a coating method such as a roller coating method or a curtain coating method. Drying is
It is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at 30° C. to 200° C. for a period of 5 minutes to 2 hours, either stationary or under ventilation.

In the present invention, the oxidation potential is determined by using a saturated calomel electrode as a reference electrode and a [1,IN(n-Bu)JOCIO40 acetone solution as an electrolyte solution, sweeping the potential of the working electrode with a potential siber, and calculating the current-potential obtained by sweeping the potential of the working electrode. The peak position of the curve was directly determined as the value of the oxidation potential.

The present invention will be explained below with reference to Examples. Parts in the examples represent parts by weight.

Example 1 An aluminum cylinder of 80φ x 360mm was used as a base, and polyamide resin (product name: Amilan CM-80
A 5% methanol solution (manufactured by Toshi Co., Ltd.) was applied by dipping to form an undercoat layer with a thickness of 1 m.

Next, add 10 parts of a disazo pigment having the following structural formula.

Polyvinyl butyral resin (product name: S-LEC BXL
, manufactured by Suikagaku Co., Ltd.) and 100 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using lφ glass beads. 50 to 100 parts of tetrahydrofuran (appropriately) was added to this dispersion and applied onto the undercoat layer, followed by drying at 100 DEG C. for 55 minutes to form a charge generating layer having a thickness of 0.15 parts m.

Next, polyethylene resin powder (trade name: Frozen 1:1142,
manufactured by Seitetsu Kagaku), a compound of the following structural formula with an oxidation potential of 0.67V as a charge transport substance, a compound of the following structural formula (corresponding to the general formula (1) above) for preventing dormant memory, and a binding agent as a binder. Bisphenol Z type polycarbonate resin (manufactured by Ondai Kasei Kasei) was prepared.

First, 20 parts of polycarbonate resin and the above charge transport material 2
0 parts, and also 0.2 parts of the above-mentioned compound for preventing dormant memory.
Pl was dissolved in 100 parts of monochlorobenzene, 6 parts of the above polyethylene resin powder was added thereto, dispersed for 50 hours in a stainless steel ball mill, and further dissolved in 20 parts of dichloroethane.
41 liquids of charge transport substances were prepared by adding 50% of the charge transport material. This solution was applied onto the generation layer and hot-dried at 100° C. for 90 minutes to form a charge transport layer with a thickness of 20 gm.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that a compound having the following structural formula and an oxidation potential of 0.54 V was used as the charge transport material.

Comparative Example 2 A photoreceptor was produced in the same manner as in Example 1, except that no lubricant powder was added.

Comparative Example 3 A photoreceptor was produced in the same manner as in Example 1, except that the compound for preventing pause memory was not added.

The above photoreceptor was subjected to a 100,000-sheet durability test by being installed in a Canon copier NP-3525 modified so that the blade penetration amount was 1.0 cm and the cleaning roller relative speed was 106%. The results are shown in Table 1.

Table 1 In Table 1, potential fluctuation refers to the dark potential (v
o') at -650V, bright area potential (VL) at -15
0v, the residual potential (vR) at that time is set to y8 such that it is -1ov, and shows the change in absolute value after a 100,000-sheet durability test. In addition, rest memory is expressed as the change in image density between the area immediately below the corona charger and other areas, or the change in potential (VO) 10 hours after the rotation of the photoreceptor was stopped after the 10,000-sheet durability test. It is something.

As can be seen from Table 1, even after the 100,000-sheet durability test, the photoreceptor of Example 1 had small potential fluctuations and small scratches on the surface layer, and no pause memory occurred, demonstrating high practical durability. On the other hand, in Comparative Example 1, which uses a charge transport material with a low oxidation potential, the potential fluctuation is large, and in Comparative Example 2, which does not use a lubricant powder, the surface layer is extremely abraded. Potential fluctuations are occurring. In addition, scratches have also occurred on the surface of the photoreceptor, and their effects are also visible on the image. Furthermore, in the photoreceptor of Comparative Example 3 to which the compound for preventing dormant memory was not added, potential fluctuations and scraping were confirmed as in Example 1, or the dormant memory was 90 V in potential.
This effect is also noticeable on the image.

Example 2 An aluminum cylinder of 80 Φ x 360 mm was used as a conductive substrate, and a 5% methanol solution of polyamide resin (product name: Amilan CM-8000, manufactured by Toshi) was applied by dipping to the bottom coat with a thickness of O, SJLm. Added layers.

Next, 10 parts of a trisazo pigment having the following structure, 6 parts of polyvinyl butyral resin (FfrJ product name: S-LEC BL-3, [hydrochemical type)], and 50 parts of cyclohexanone were dispersed in a Santo 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 lm.

Next, as a lubricant powder (fluorine-based resin powder), 4-fluorochemically modified tyrene resin powder (trade name: Lublon: L-2, manufactured by Daikin Industries) was used, and as a charge transport substance, the following structural formula (% formula %) was used to prevent pause memory. The compounds shown in Table 2 were prepared as compounds for use in the test, and bisphenol Z type car recarbonate resin (manufactured by Konjin Kasei Co., Ltd.) was prepared as a binder.

Table 2 Table 2 (Continued) Photoreceptors were prepared using the compounds listed in Table 2 in the same manner as in Example 1. The amount of trifluorine resin powder added is 2 for 20 parts of charge transport material and 20 parts of rejuvenating agent binder.
The addition fit of the compound for preventing dormant memory is 0.
．． For compound NO.1, if it is 2 parts, then 0.05
There were five levels: part, 0, 1 part, 0.5 part, 1.0 part, and 5.0 part.

Table 3 shows the results of evaluating the above photoreceptors.
A laser beam printer of an image scan reversal development type was used, which had a cleaning blade with a penetration i of 1.0 mm and used a two-component developer consisting of toner and carrier. In Table 3, the potential fluctuation is defined as the absolute value after the 10,000-sheet durability test by setting the dark area potential to -600V, the dark area potential to -150V, and the residual potential at that time to -10V at the initial stage of the durability test. This shows the amount of change. Regarding the pause memory, the measuring method is the same as in Example 1, but since reversal development is used, the change in image density appears in the direction of increasing density, contrary to Example 1.

Table 3 (% by weight: % by weight based on the total amount of charge transport material and binder) As can be seen from Table 3, in the system in which the compound corresponding to the general formula (1) was added, it was clear that compounds with other structures were added. The effect of preventing dormant memory is better than that of the case where the method is used, and there is less adverse effect on potential fluctuations, etc. Furthermore, even if the amount of the compound added to the general formula (1) is changed,
It has a high dormant memory prevention effect, and also has high potential stability without causing any increase in residual potential.

Example 3 An 80φ x 360mm aluminum cylinder was used as a base, and polyamide resin (product name: Amilan CM-8
A 5% methanol solution of 000 (manufactured by Toshi Co., Ltd.) was applied by a dipping method to provide an undercoat layer of Igm thickness.

Next, 10 parts of a disazo pigment having the following structural formula, 6 parts of polyvinyl butyral resin (trade name: S-LEC BL-3, manufactured by Ueki Kagaku), and 50 parts of cyclohexanone were dispersed using a Santomill trowel using glass beads. Add 100 parts of methyl ethyl ketone to this dispersion and apply it on the undercoat layer.
．． A charge generation layer having a thickness of 2 gm was formed.

next,! Graphite fluoride (manufactured by Daikin Industries, Ltd.) as the carbon hexide-based powder, the same compound as in Example 1 as the compound for preventing dormant memory, and the compounds shown in Table 4 as the charge transporting substance.
A bisphenol Z type polycarbonate resin (manufactured by Ondai Kasei) was prepared as a binder.

Table 4 Hereinafter, a photoreceptor was prepared using the charge transport materials listed in Table 4 in the same manner as in Example 1. The amount added is 0.2 part.

The above photoreceptor was evaluated in the same manner as in Example 1, and the results are shown in Table 5.

Table 5 As can be seen from the table, the oxidation potential of the charge transport material is 0.6 V.
It can be seen that those with less than 0.6 parts are excellent in preventing dormant memory, but the potential fluctuation is larger than when using 0.6 parts or more.

Example 4 An aluminum cylinder of 80φ x 360mm was used as a base, and polyamide resin (trade name: Amilan CM-8) was applied to it.
A 5% methanol solution (manufactured by Toshi Co., Ltd.) was applied by dipping to form an undercoat layer with a thickness of lpm.

Next, 10 parts of a disazo pigment having the following structural formula, 6 parts of polyvinyl butyral resin (trade name: Eslec BXL, manufactured by Tsukiki Chemical Co., Ltd.), and 100 parts of cyclohexanone were dispersed for 20 hours using a Santomill apparatus using lφ glass beads.

50 to 100 parts of tetrahydrofuran was added to this dispersion, which was applied onto the undercoat layer, and dried at 100 DEG C. for 15 minutes to form a charge-generating layer with a thickness of 0.15 gm.

Next, as a fluorine-based resin powder, 4-fluorochemically modified tyrene resin powder (
Product name: Lugulon L-2 (manufactured by Daikin Industries), a compound with the following structural formula as a charge transport substance (oxidation potential: 0.66 V)
.

The same compound as in Example 1 was prepared as a compound for preventing dormant memory, and bisphenol Z type polycarbonate resin (manufactured by Ondai Kasei) was prepared as a rejuvenator binder. below,
By the same method as in Example 1, the amount of the tetrafluoroethylene resin powder added was adjusted to 1.0% with respect to the total amount of the charge transport material and binder in the surface layer. Photoreceptors were prepared in which the concentration was changed to three levels: +0.0.30% by weight.

The above photoreceptor was evaluated in the same manner as in Example 1, and the results are shown in Table 6.

Table 6 As can be seen from the table, even if the amount of lubricant powder added is changed, it is highly effective in preventing abrasion of the photoreceptor, the surface is less likely to be scratched, and image stains due to toner filming are less likely to occur. Furthermore, there is no increase in residual potential, and the potential stability is good.

Example 5 An undercoat layer was applied on the base of an 80φ cylinder in the same manner as in Example 4. Next, 15 parts of the hydrazone compound used in Example 1 and 10 parts of polycarbonate Z resin were mixed with 50 parts of dichloromethane and monochlorobenzene. A solution containing 10 parts of the solution was applied onto the undercoat layer to form a charge transport layer with a thickness of 15 parts and m. Next, 4 parts of the same disazo pigment used in Example 1,
A CG dispersion (2) was prepared by dispersing 10 parts of polycarbonate Z resin and 50 parts of cyclohexanone in a sand mill using lφ glass beads for 20 hours.

Next, polytetrafluorochemically modified tyrene resin powder, a fluorine-based acrylic oligomer as a dispersant, the above hydrazone compound, and borica'
- Bonate Z resin was prepared. First, 10 parts of polycarbonate resin, 4 parts of hydrazone compound, and 0.15 parts of fluorine-based acrylic oligomer are dissolved in 10 parts of dichloromethane and 40 parts of monochlorobenzene. Next, 1.5 parts of polytetrafluoroethylene resin powder was added to the mixture and dispersed in a stainless steel ball mill for 40 hours. Furthermore, 0.3 part of the dormant memory prevention compound used in Example 1 was added to this liquid, and CT liquid ■
was prepared. A paint obtained by mixing the CG dispersion liquid (■) and the CT liquid (■) in a ratio of l=1 was applied onto the charge transport layer, and 5IL
A charge generation layer having a thickness of m was formed.

The copying machine used in Example 1 was modified so that it could be positively charged, and this photoconductor was evaluated in the same manner as in Example 1. Even after a 10,000-sheet durability test, there were no potential fluctuations, no scraping of the photoconductor, and no dead memory. A small, high-quality copy was obtained.

Comparative Example 4 As a comparative example of Example 5, a photoreceptor without any pause memory prevention compound was prepared and the same evaluation was conducted. After a 100,000-sheet durability test, pause memory appeared on the image and the potential also decreased by ΔV.
O=-160V.

[Effects of the Invention] According to the present invention, the durability of the electrophotographic surface is excellent, so the potential fluctuation of the photoreceptor is small, and the mechanical durability is excellent, so there is less abrasion of the photoreceptor. An excellent electrophotographic photoreceptor with a long body life and a significantly suppressed photoreceptor pause memory, with no local shading abnormalities in the resulting images, can be obtained.

, 62 patent attorneys Sekimi Yamashita

Claims (5)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least the layer farthest from the substrate includes one or more lubricant powders, one or more charge transport substances having an oxidation potential of 0.6 V or more, and an electrophotographic photoreceptor containing a compound represented by the following general formula (1). General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and X_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲Mathematical formulas, There are chemical formulas, tables, etc. ▼, X_2 is a hydrogen atom, carbon number is 1~
10 alkyl group or an alkenyl group having 2 to 10 carbon atoms] (2) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a laminated structure consisting of a charge generation layer and a charge transport layer, and the charge transport layer is provided on the charge generation layer. (3) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a laminated structure consisting of a charge generation layer and a charge transport layer, and the charge generation layer is provided on the charge transport layer. (4) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer comprises a single layer containing a charge generating substance and a charge transporting substance. (5) The electrophotographic photoreceptor according to claim 1, wherein the lubricant powder is a fluororesin powder, a polyolefin resin powder, or a fluorocarbon powder.