JPH01292349A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance mechanical durability, potential stability under an environment exposed to corona discharge, and image quality by incorporating a lubricant powder, an electric charge transfer material specified in oxidation potential, and two kinds of organic compound specified in structure. CONSTITUTION:The electrophotographic sensitive body is obtained by forming a photosensitive layer on a conductive substrate, and a layer located farthest from the conductive substrate contains the lubricant powder, the charge transfer material having an oxidation potential of <0.6V, and each of the organic compounds represented by formulae I and II in which X1 is -C(CH3)2-CH3 or -C(CH3)2-CH2CH3; X2 is H, 1-10 C alkyl, or 2-10C alkenyl; each of R1 and R2 is H or 1-10 C alkyl; and each of m and n is an integer of 10-20. The addition of said compounds of formulae I and II has an effect of protecting the charge transfer material from oxidation by ozone or NOx, because they undergo the oxidation preferentially to the charge transfer material, and the oxidation products do not adversely affect the other electrophotographic characteristics.

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 electrophotographic copying machines, 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 photoreceptors using these organic photoconductors have already been developed, particularly for charge generation layers and charge transport layers. Laminated, functionally separated types have been put into practical use and are installed in copiers and printers.

However, these photoreceptors generally have poor mechanical durability against abrasion and scratches on the surface of the photoreceptor, as well as electrophotographic properties against reductions in sensitivity, fluctuations in residual potential, reductions in charging ability, image blurring, etc. The durability was not sufficient.

In order to improve mechanical durability, Japanese Patent Application Laid-Open No. 56-2574
Publication No. 6, Publication No. 56-25749, Publication No. 61-123
As described in Japanese Patent No. 850, etc., it is known to disperse lubricant powder such as fluororesin powder, polyolefin resin powder, or carbon fluoride in the surface layer of a photoreceptor.

However, with a photoreceptor in which lubricant powder is not dispersed, the deteriorated surface is scraped away by active species such as ozone and No. 8 generated during corona discharge, so a new, undeteriorated surface always appears. With a photoreceptor in which powder is dispersed, abrasion is significantly reduced, and new surfaces are not sufficiently exposed.
Therefore, when used for a long period of time, the image becomes distorted and it becomes difficult to distinguish the characters.

So-called image blurring occurs.

Therefore, the inventors of IJI solved the image blurring when lubricant powder was dispersed by using a compound with an oxidation potential of 0.6 V or more as a charge transport substance contained in the surface layer (Japanese Patent Application Laid-Open No. 83-30850).

However, a new problem with this photoconductor is that after continuous use of the photoconductor, if a signal is sent to the copying machine for a long period of time, the charging ability of the portion of the photoconductor close to the charger that performs corona discharge will apparently decrease. It has been pointed out that a phenomenon in which white streaks appear on an image, so-called white spots, occurs. This white spot is a peculiar phenomenon when a charge transport material having an oxidation potential of 0.8 V or more is used, and is not observed at all in a charge transport material having a low oxidation potential of less than o, e v.

Similar to the aforementioned image blur, the occurrence of white spots is caused by ozone and NOx generated during corona discharge.If the oxidation potential of the charge transport material is less than 0.6V, the charge transport material itself is exposed to the surface of the photoreceptor. However, in the case of a charge transport material with an oxidation potential of 0.6μ or higher, the charge transport material is oxidized by the action of ozone, NOx, etc., resulting in lower resistance and image blurring. Ozone and NOo penetrate deep into the photoreceptor and oxidize the charge-generating substance, lowering the resistance and promoting hole injection from the substrate.The apparent upper potential does not rise and white spots occur. It is estimated to be. This apparent potential drop occurs even during continuous use, but because the drop in surface orientation occurs uniformly on the photoconductor surface, it cannot be recognized as white spots, which is a partial potential drop. First, when the charger is left after continuous use, a local potential drop near the charger where ozone or NOx concentrations are extremely high becomes noticeable as white spots.

[Problems to be Solved by the Invention] The present invention provides an electrophotographic photoreceptor having high durability that solves the above-mentioned problems. In other words, the purpose of Suekan 1!1 is to provide an electrophotographic photoreceptor with high durability that has less surface abrasion and scratches due to JI rubbing, and that can produce high-quality images without image blurring or white spots (11). Another object of the present invention is to provide an electrophotographic photoreceptor having good cleaning properties and high durability without toner adhesion to the surface layer. Still another object of the present invention is to provide an electrophotographic photoreceptor that has high durability and does not accumulate residual potential in repeated electrophotographic processes and can always produce high quality images.

[Means for solving the problem] The problem is as follows: In an electrophotographic photoreceptor having a photosensitive layer on a photosensitive support, at least the layer farthest from the support contains a lubricant powder, a charge transport material with an oxidation potential of less than 0.6 V, and the following general formula (1). , (2) is solved by an electrophotographic photoreceptor characterized by containing the compound represented by (2).

General formula (1) X7 is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a fulkenyl group having 2 to 10 carbon atoms. ) General formula (2) (In the formula, R11R2 is each a hydrogen atom, carbon number 1 to 1
O is an alkyl group, and m and n are integers of 10 to 20. ) In the present invention, the addition of the compounds represented by the general formulas (1) and (2) can be used as a charge transport substance such as ozone, NO, etc.

It has the effect of protecting against the oxidative effects of That is, the general formula (1
) and (2) are preferentially oxidized by ozone and NO over charge transport substances, and their oxidized deterioration products do not adversely affect other electrophotographic properties. The book) AIJ will be explained in detail below.

The photosensitive layer containing an organic photoconductive material in Unreleased No. 11 is a single-layer photoreceptor in which a charge-generating material and a charge-transporting material are mixed, which are separated by a moat, or a charge-generating layer containing a charge-generating material and a charge-transporting material. It takes the form of a laminated photoreceptor, etc., in which a charge transport layer containing a charge transport layer is laminated.

Examples of charge-generating substances include biryllium, thiopyrylium dyes, phthalosifune pigments, anthoanthrone pigments,
Perylene pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, and the like can be used.

In the present invention, charge transport substances having a butylation potential of less than 0.6 V include hydrazone compounds, stilbene compounds, carbazole compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, and polyarylalkane compounds. Selected from Also,
Two or more of these charge transport materials can be used in combination.

Charge transport materials generally have a low molecular weight and cannot be used to form a film by themselves, so it is necessary to use a resin with film-forming properties as a binder. The binder resin is not particularly limited as long as it is a polymeric compound with film-forming properties, but polymethacrylic acid esters, polycarbonates, and holograms are recommended because they have a certain degree of hardness even when used alone and do not interfere with carrier transport. Arylate, polyester, polysulfone, etc. are preferred.

The binder resin contained in the layer farthest from the conductive support is usually used in an amount of about 10 to 1000 parts by weight per 100 parts by weight of the charge transport material.

Examples of the lubricant powder used in the present invention include tetrafluoroethylene resin powder, trifluorochloroethylene resin powder, hexafluoroethylene propylene resin powder, vinyl fluoride resin powder, and vinylidene fluoride resin. Fluororesin powders such as powders, niphfluorinated dichloride ethylene resin powders, and copolymers of monomers constituting these polymers; polyethylene resin powders, polypropylene resin powders, and copolymers of monomers constituting these polymers. Examples include polyolefin resin powder such as; and fluorinated carbon. Among these, preferred are tetrafluoroethylene resin, vinylidene fluoride resin, and polyethylene resin from the viewpoint of slipperiness, abrasion resistance, and GL type properties;
Two or more of these lubricant powders can also be used in combination.

The content of the lubricant powder dispersed in the layer farthest from the conductive support is the sum of the charge transport substance and the binder (if the core layer contains a charge generation substance, the charge generation substance). 1.0 to 3% by weight based on the amount of Offi is suitable, and particularly preferably 2.0 to 20% by weight.

When it exceeds fflfit%, the light transmittance decreases, and furthermore,
Carrier mobility also tends to decrease.

Examples of the compounds represented by the general formulas (+) and (2) used in the present invention include the following compounds.

t-C, l19 t-C, Il, + t-C,lls t-C,H.

Cl1(C113)2 C1,CH-CHz-CHi t-C4H.

C112CII 2 These compounds are one of the phenol derivatives with a hinted phenol group, which is known as a radical scavenger or antioxidant for plastics, rubber, etc., and a sulfide derivative, which is known as a hydroperoxide decomposer. It is one of the compounds. Furthermore, two or more of these compounds can also be used in combination.

General formula (1) contained in the layer farthest from the conductive support
), the content of the compound represented by (2) is.

The total amount of charge transporting material and binder (if the core layer contains a charge generating material, further charge generating material) is usually 0.1 to 30% by weight based on the total weight of the binder.
．． 2 to 10i amount% is preferable, the additive is 0.1 ton H,i
If it is less than %, the deterioration prevention effect will be small and 230 nails! If it exceeds -%, there is a tendency for problems such as a decrease in sensitivity and an increase in the residual potential to occur.

When manufacturing the electrophotographic photoreceptor of the present invention, examples of the conductive support include those whose support body has conductivity, such as aluminum and aluminum alloys.

Copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used.In addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. can be used. Plastic with a layer formed by vapor deposition.

Supports in which conductive particles such as titanium oxide or tin oxide are coated on plastic or the above-mentioned conductive support together with a suitable binder, supports in which plastic or paper is impregnated with conductive particles, plastics containing conductive polymers, etc. can be used.

A subbing layer having a barrier function and an adhesive fi can also be provided between the conductive support and the photosensitive layer.

The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon s1o, R polymerized nylon, alkoxymethylated nylon, etc.), polyurethane,
It can be formed from gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0. 1 lm to 40 lm, preferably
0.3 gm to 3 Im is suitable.

As a method for dispersing the lubricant powder, general 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. This is prepared by mixing an appropriate amount with a solution in which a binder, a charge transporting substance, and a compound represented by the general formulas (1) and (2) are dissolved.

Furthermore, various dispersion aids can be added to improve the dispersibility when dispersing the lubricant powder.

Coating methods include dip coating method, spray coating method, spinner coating method, bead coating method,
Coating can be carried out using coating methods such as Mayer bar coating, blade coach ink method, roller coating method, and curtain coating method. For drying, 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 with air blowing.

At unexploded +11, the oxidation potential was set using a saturated calomel electrode as the reference electrode, O, 1N(r+-Bu)4? Using l'ClO4 acetonitrile solution as the electrolyte, the potential of the working electrode was swept by a potential sweeper, and the obtained ? The peak position of the lf current-potential curve was directly determined as the value of the oxidation potential.

For details, please refer to sample 0. IN(n-Bu)N-C1O
-n acetonitrile solution electrolyte solution 5~10tso1%
Dissolve to a certain concentration. Then, a voltage is applied to this sample solution, and a current change is measured when the voltage is changed linearly from a low potential to obtain a current-potential curve.

In this 1, the potential value corresponding to the first inflection point of the 'iTt current value in the current-potential curve was set as the oxidation level.

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×360m5 was prepared as a conductive support.

On the other hand, 100 parts of conductive powder coated with tin oxide containing 10% antimony oxide at a ratio of 75 parts to 1% to titanium oxide was mixed with resol-based phenol mii o o.
The mixture was added to a solution consisting of 30 parts of methanol, 100 parts of methyl cellosolve, and well dispersed using a ball mill to form a paint. This paint was dip coated onto a support and heated at 140℃ for 3 hours.
It was heated and cured for 0 minutes to form a 20 μm conductive undercoat layer.

On top of this, 1 part of polyamide resin (6-66-610-124 nylon copolymer) and 3 parts of 8-nylon resin (methoxymethylated 6 nylon, methoxylation rate 30%) were added to 50 parts of methanol, butane/- A coating solution prepared by dissolving 40 parts of a solvent in a solvent was applied by dipping, and after drying at 70° C. for 10 minutes, a 0.5 gm thick undercoat layer was formed.

Next, 10 parts of a bisazo pigment of the following structural formula (3), 5 parts of polyvinyl butyral resin, and 100 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using 1φ glass beads. Add 50 to 100 (appropriate) parts of tetrahydrofuran to this dispersion, spread it on the undercoat layer, dry it at 100°C for 5 minutes, and dry the eel at 100°C for 5 minutes.
A charge generation layer having a thickness of 12 μm was formed.

Next, we use tetrafluoroethylene shelf fat powder, a fluorine-based acrylic oligomer as a dispersant, and an oxidation potential of 0.0 as a charge transport material.
57V hydrazone compound of the following formula (abbreviated as CT-1) Bisphenol Z type polycarbonate resin was prepared as a binding agent binder. First polycarbonate resin 20
1 part, 20 parts of a hydrazone compound, and 0.6 part of a fluorine-based acrylic oligomer are dissolved in 100 parts of monochlorobenzene. Next, 6 parts of tetrafluoroethylene resin powder was added to this and dispersed in a stainless steel ball mill for 40 hours to form a compound of the following structural formula (5) (which corresponds to the formula (1) above).
A charge transport layer was formed by adding 20BB of a dichloromethane solution in which 0.4 parts of each of the compound of structural formula (6) (corresponding to formula (2) (abbreviation TP-1)) was dissolved. A coating solution was prepared.This solution was coated on the charge generation layer, and dried with hot air at 10.0°C for 60 minutes.
A charge transport layer having a thickness of Lm was formed.

The photoconductor manufactured in this way was penetrated by a blade! 1.1
Canon copier MP-, modified to have a cleaning mechanism with a sponge roller relative speed of 102%.
3525 and evaluated its durability, no blurring occurred even after 100,000 sheets of durability testing, and high-resolution R Yabu copies (
I was able to do 5I. At this time, the amount of decrease in the photoreceptor film thickness is 1
．． It was 51 parts m. In addition, after making 5,000 continuous copies using another photoconductor made in the same way, the photoconductor was left in the copying machine for 3 days and the surface pattern was measured. i) The part of the photoreceptor located directly under the electric appliance was marked and the potential difference (ΔVo) with other parts was determined, but no difference was observed.

Examples 2 to 14 Below, vinylidene fluoride resin powder, difluoride dichloride ethylene resin powder, polyethylene powder, and carbon fluoride were used as lubricant powders, and the above CT-1 and oxidation potential were used as charge transport materials. A compound of structural formula (7) (abbreviation C↑-2) with an oxidation potential of 0.54V and structural formula (8) (abbreviation CT-3) with an oxidation potential of 0.47V, and the above - formula (+), (2) Table 1 shows the results of the same evaluation as in Example 1 for a photoreceptor manufactured in the same manner as in Example 1 using the compounds shown in Table 1 in addition to HPtIA-1 and TP-1 as compounds corresponding to the above. Summarized in 2.

Examples 15-20 +? Table 2 shows the evaluation results for photoreceptors manufactured in the same manner as in Example 1 except that the addition L of the compounds represented by formulas (1) and (2) was changed.

Table 1 Table / (7゛zuno dog/(--°y) Comparative examples 1 to 11 From the composition of the example, the lubricant powder or the formula (1) above.

A photoreceptor lacking the compound represented by (2)! ! ! It was crushed and evaluated in the same manner as in Example 1. In addition, the acid t shown in Table 3
a photoreceptor using a charge transport material with a voltage of 0.8 V or more;
Table 4 shows the evaluation results of photoreceptors using the additives shown in Table 1 alone.

Table 3 As shown in Table 4, the photoreceptor without the addition or combination of the compounds represented by the formulas (1) and (2) has a 3000
Blur started to appear after ~4,000 sheets, and after a durability test of 10,000 sheets, the image was completely unrecognizable.In addition, photoreceptors that do not contain polytetrafluoroethylene resin powder, which is lubricant powder, Due to the drastic decrease in film thickness on the surface of the photoconductor during durability tests, fogging began to occur after about 35,000 sheets.
After the 00,000-sheet durability test, it was difficult to distinguish the letters from the letters.

In addition, although photoreceptors using charge transport materials with an oxidation potential of O, SV or higher did not cause blurring during durability tests, when left in a copying machine for 311 hours, the potential at the area under the belt plate decreased. However, a noticeable white spot appeared on one image.

Example 21 In the same manner as in Example 1, an 80φ cylinder was coated on a substrate up to the undercoat layer. Next, 15 parts of the hydrazone compound (CT-1) used in Example 1 and 10 parts of polycarbonate Z resin were mixed with dichloromethane. 50 parts, monochlorobenzene 1
A solution dissolved in 0 parts of the above solution was applied onto the undercoat layer to form a charge transport layer having a thickness of 15 ILm.

Next, 4 parts of a disazo pigment having the following structural formula, 10 parts of polycarbonate ZwI fat, and 50 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using 1φ glass beads to prepare a charge generation layer dispersion.

Next, a tetrafluoroethylene resin powder, a tefluoroacrylic oligomer as a dispersant, and a hydrazone compound (CT-1) were added.
, polycarbonate Z resin was prepared.

First, 10 parts of polycarbonate resin, 4 parts of hydrazone compound
0.15 parts of fluorine-based acrylic oligomer were 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 the mixture was dispersed in a stainless steel ball mill for 40 hours.

Further, in this liquid, the formulas (1) and (2) used in Example 1 were added.
0.3 parts of each of the compounds represented by ) were added to prepare a charge transport layer solution (2). A paint obtained by mixing the charge generation layer dispersion liquid (1) and the charge transport layer liquid (2) at a ratio of 1:1 was applied onto the charge transport layer to form a charge generation layer of 5 gmg.

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.
Even after a 10,000-sheet durability test, no blurring occurred and high-quality copies were made (
I was able to do it. The amount of decrease in the film thickness of the photoreceptor at this time was 2.5 #Lm.

Also, even if the photoreceptor is left in a copying machine after the durability test, there will be a potential difference (YVo) in the part directly under the charger with other parts.
was hardly observed, and no white spots occurred.

Comparative Example 12 As a comparative example of Example 21, a photoreceptor without the addition of the compounds represented by formulas (1) and (2) was manufactured and evaluated in the same way, but blurring began to occur after about a few thousand sheets. .

[Effects of the Invention] As described above, the lubricant powder of the present invention, the charge transport substance having an oxidation potential of less than 0.6 parts, and the organic compound having a specific structure are combined.
Electrophotographic photoreceptors containing the above-mentioned types have extremely high mechanical durability and potential stability in a corona discharge environment, and can always produce stable, high-quality images.

Further, the electrophotographic photoreceptor of the present invention can be used not only for ordinary copying machines but also as a photoreceptor for printers that apply electrophotography, such as laser beam printers, LED printers, LCD printers, and CRT printers.

Claims (5)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive support, at least the layer farthest from the support contains a lubricant powder, a charge transport substance with an oxidation potential of less than 0.6 V, and the following general formula: An electrophotographic photoreceptor characterized by containing a compound represented by (1) or (2). General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, X_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, It is an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms.) General formula (2) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (In the formula, R_1 and R_2 are hydrogen atoms and carbon numbers, respectively. 1
-10 alkyl group, m and n are integers of 10-20. (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.