JP2644280B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high sensitivity and durability widely used in electrophotographic application fields such as electrophotographic copying machines, laser beam printers, CRT printers, and electrophotographic plate making systems. The present invention relates to an electrophotographic photoreceptor excellent in the above.

[Prior art] In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoreceptors. Among photoreceptors using these organic photoconductive materials, particularly, a charge generation layer and a charge transport layer have been already used. The stacked function-separated type is commercialized and installed in copiers and printers. However, these photoreceptors generally have mechanical durability against abrasion and scratches on the surface of the photoreceptor, decrease in sensitivity, fluctuation in residual potential, decrease in charging ability, and decrease in electrophotographic characteristics against image blur. The durability was not enough.

In order to improve mechanical durability, JP-A-56-25746, JP-A-56-25749, and a fluorine-based resin powder on the photoconductor surface layer as described in JP-A-61-123850, etc. It is known to disperse lubricant powder such as polyolefin resin powder and carbon fluoride.

However, whereas since the photoreceptor does not distribute the lubricant powder surface degraded by active species of the ozone and NO _x and the like generated during corona discharge shaved surface not always new deterioration has appeared, smooth In the case of the photoreceptor in which the material powder is dispersed, the amount of shaving is remarkably reduced, so that a new surface does not sufficiently appear.

Therefore, the present inventors use a compound having an oxidation potential of 0.6 V or more as a charge transport material contained in the surface layer,
Image blur when lubricant powder is dispersed is eliminated
63-30850).

However, as a new problem with this photoreceptor, if the photoreceptor is continuously used and then left in a copying machine for a long period of time, the charging ability of the portion of the photoreceptor near the charger that performs corona discharge apparently decreases, and the It has been pointed out that a phenomenon in which white stripes occur, that is, a so-called white drop occurs. This white drop is a peculiar phenomenon when a charge transporting substance having an oxidation potential of 0.6 V or more is used, and is not seen at all in a charge transporting substance having a low oxidation potential of less than 0.6 V.

Generation of white spots are attributable to ozone and NO _x generated during similar corona discharge and an image blur of the foregoing, when the oxidation potential of the charge transporting material is less than 0.6V, the charge transport material itself photoreceptor surface in receiving oxidized by the action such as ozone and NO _x while the image blur lower resistance is occurring, the oxidation potential is 0.
Oxidizing a charge generation material to penetrate ozone and NO _x in the charge transporting material is less susceptible to oxidation until photoreceptor deep layer in the case of 6V or more charge transport materials, hole from infrastructure in order to reduce the resistance of It is presumed that the injection was promoted and the potential did not increase apparently and white spots occurred. Although this apparent potential drop occurs even during continuous use, the drop in surface potential is not recognized as a white drop, which is a partial potential drop because the surface potential uniformly occurs on the photoreceptor surface, and after continuous use. upon standing, in which local potential drop at extremely high charger vicinity ozone and concentration of NO _x is remarkably surfaced become white spots.

[Problems to be Solved by the Invention] The present invention is to provide an electrophotographic photosensitive member having high durability and solving the above-mentioned problems. That is, an object of the present invention is to provide an electrophotographic photoreceptor having a high durability with which a high-quality image free from image blurring and white spots can be obtained with less occurrence of surface wear and scratches due to rubbing. .
It is another object of the present invention to provide an electrophotographic photoreceptor having good cleaning properties and high durability without toner adherence to the surface layer. Still another object of the present invention is to provide an electrophotographic photosensitive member having high durability and capable of always obtaining a high-quality image without accumulation of residual potential in a repeated electrophotographic process.

[Means for Solving the Problems] The problem is that, in an electrophotographic photosensitive member having a photosensitive layer on a conductive support, at least a layer farthest from the support has a lubricant powder and an oxidation potential of 0.6 V Less than a charge transport material,
And an electrophotographic photoreceptor characterized by containing a compound represented by the following general formula (1).

General formula (1) [Where R is And X ₁ is X ₂ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms.] In the present invention, the addition of the compound represented by the general formula (1) changes the charge transporting substance to ozone or the effect of protecting from oxidation, such as NO _x. That is, the compound of the general formula (1) are those subjected to oxidation than the charge-transporting material preferentially ozone and NO _x, also oxidative degradation product thereof does not adversely affect the other electrophotographic properties .

 Hereinafter, the present invention will be described in detail.

The photosensitive layer containing an organic photoconductive material according to the present invention includes a single-layer type photoreceptor in which a charge-separated charge-generating material and a charge-transporting material are mixed, or a charge-generating layer containing a charge-generating material and a charge-transporting material It takes the form of a laminated photoreceptor having a charge transport layer laminated thereon.

As the charge generating substance, pyrylium, thiopyrylium dye, phthalocyanine pigment, anthantrone pigment, perylene pigment, sivenzpyrenequinone pigment, pyranthrone pigment, trisazo pigment, disazo pigment, azo pigment, indigo pigment, quinacridone pigment, or the like is used. be able to.

The charge transport material having an oxidation potential of less than 0.6 V in the present invention is a hydrazone compound, a stilbene compound, a carbazole compound, a pyrazoline compound, an oxazole compound, a thiazole compound, a triarylmethane compound, or a polyarylalkane. Selected. Also,
These charge transport materials can be used in combination of two or more.

Since the charge transport material generally has a low molecular weight and cannot form a film by itself, it is necessary to use a resin having film forming properties as a binder. The binder resin is not particularly limited as long as it is a polymer compound having a film-forming property, but from the viewpoint that it has a certain degree of hardness by itself and does not hinder carrier transport, polymethacrylates, polycarbonates, polyolefins, and the like. Preferred are arylate, polyester, polysulfone and the like.

The binder resin contained in the layer farthest from the conductive support is usually 1 to 100 parts by weight of the charge transporting substance.
About 0 to 1000 parts by weight are used.

As the lubricant powder used in the present invention, for example, ethylene tetrafluoride resin powder, ethylene trifluoride chloride resin powder, hexafluoroethylene propylene resin powder, vinyl fluoride resin powder, vinylidene fluoride resin Powder, fluorine-based resin powder such as ethylene difluoride dichloride resin powder, and copolymers of monomers constituting these polymers; polyethylene resin powder;
Polyolefin resin powders such as polypropylene resin powders and copolymers of monomers constituting these polymers; and carbon fluoride. Among these, slipperiness,
Ethylene tetrafluoride resin, vinylidene fluoride resin, and polyethylene resin are preferable from the viewpoint of wear resistance and mold release properties. Further, these lubricant powders can be used in combination of two or more kinds.

The content of the lubricant powder dispersed in the layer farthest from the conductive support is determined by the sum of the charge transporting substance and the binder (and, if the layer contains a charge generating substance, further the charge generating substance). 1.0 to 30% by weight based on the amount is appropriate, especially
When the content is less than 1.0% by weight, the surface modification effect by the dispersion of the lubricant powder is not sufficient, while when the content exceeds 30% by weight, the light transmittance is reduced, and Mobility also tends to decrease.

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

These compounds are one of the phenol derivatives having a hindered phenol group known as radical scavengers or antioxidants such as plastics and rubbers. These compounds may be used in combination of two or more.

The content of the compound represented by the general formula (1) contained in the layer farthest from the conductive support may be a charge transporting substance (or, if the layer contains a charge generating substance, a charge generating substance, ) Usually 0.1 to 3 based on the total amount of binder
0% by weight is suitable and 0.2 to 10% by weight is preferred. When the amount of the additive is less than 0.1% by weight, the effect of preventing deterioration is small.

When producing the electrophotographic photoreceptor of the present invention, as the conductive support, a support having conductivity itself, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel , Indium, gold, platinum, and the like can be used. In addition, plastic, titanium oxide, and oxide having a layer in which aluminum, an aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, or the like is formed by a vacuum evaporation method can be used. It is possible to use a support in which conductive particles such as tin are coated on a plastic or the conductive support together with a suitable binder, a support in which conductive particles are impregnated in plastic or paper, or a plastic having a conductive polymer. it can.

An undercoat layer having a barrier function and an adhesive function may 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 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, It can be formed of gelatin, aluminum oxide, or the like.

The thickness of the undercoat layer is 0.1 μm to 40 μm, preferably 0.3 μm.
μm to 3 μm is appropriate.

As a method of dispersing the lubricant powder, general dispersing means such as a homogenizer, an ultrasonic wave, a ball mill, a vibration mill, a sand mill, an attritor, and a roll mill can be used. After the lubricant powder is added to the binder dissolved in an appropriate solvent, it is dispersed by the above dispersion method. This is prepared by mixing an appropriate amount of a solution in which a binder, a charge transport material and the compound represented by the general formula (1) are dissolved.
In addition, it is also possible to add various dispersing aids to improve dispersibility when dispersing the lubricant powder.

Coating can be performed using a coating method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a Meyer bar coating method, a blade coating method, a roller coating method, and a curtain coating method. Drying is preferably performed by contact drying at room temperature and then heating and drying. The heating and drying can be performed at 30 ° C. to 200 ° C. for 5 minutes to 2 hours in a stationary or blown state.

In the present invention, the oxidation potential reference electrode saturated calomel _{electrode, 0.1N (n-Bu) 4} N + ClO 4 - with acetonitrile solution as an electrolytic solution, and sweeping the potential of the working electrode by the potential sweeper, resulting current The peak position of the potential curve was determined as the oxidation potential value.

Specifically, the sample is dissolved in an electrolyte solution of a 0.1 N (n-Bu) N ⁺ ClO ^- ₄ acetonitrile solution to a concentration of about 5 to 10 mmol%. Then, a voltage is applied to this sample solution, and a current change when the voltage is changed linearly from a low potential is measured to obtain a current-potential curve. The potential value corresponding to the first inflection point of the current value in this current-potential curve was defined as the oxidation potential.

Hereinafter, the present invention will be described with reference to examples. Parts in Examples are parts by weight.

Example 1 An 80φ × 360 mm aluminum cylinder was prepared as a conductive support.

On the other hand, 100 parts of conductive powder coated with tin oxide containing 10% of antimony oxide to 75% by weight of titanium oxide is composed of 100 parts of resole phenolic resin, 30 parts of methanol, and 100 parts of methyl cellosolve. To the solution,
It was well dispersed in a ball mill to give a coating. This paint was applied on the support by dip coating and cured by heating at 140 ° C for 30 minutes.
m of the conductive undercoat layer was provided.

On top of this, 1 part of a polyamide resin (6-66-610-12 quaternary nylon copolymer) and 3 parts of an 8-nylon resin (methoxymethylated 6 nylon, methoxylation ratio of about 30%) were mixed with 50 parts of methanol and 40 parts of butanol. The coating solution dissolved in the solvent consisting of
A thick undercoat layer was provided.

Next, 10 parts of a bisazo pigment of the following structural formula (2) and 5 parts of a polyvinyl butyral resin And 100 parts of cyclohexanone were dispersed in a sand mill using 1φ glass beads for 20 hours. To this dispersion, 50 to 100 parts (as appropriate) of tetrahydrofuran was added and applied onto the undercoat layer, followed by drying at 100 ° C. for 5 minutes to form a 0.12 μm charge generation layer.

Next, ethylene tetrafluoride resin powder, a fluorinated acrylic oligomer as a dispersant, and an oxidation potential of 0.
57V hydrazone compound of the following formula (3) (abbreviated as CT-1) A bisphenol Z-type polycarbonate resin was prepared as a binder. First, polycarbonate resin 20
Parts, 20 parts of a hydrazone compound and 0.6 parts of a fluorinated acrylic oligomer are dissolved in 100 parts of monochlorobenzene. Then, 6 parts of a tetrafluoroethylene resin powder was added thereto, and the mixture was dispersed in a stainless steel ball mill for 40 hours to give a compound of the following structural formula (4) (corresponding to the general formula (1)) (abbreviation)
HBCY-1) 20 parts of a dichloromethane solution dissolved with 0.4 part of HBCY-1 was added to prepare a charge transport layer coating solution. This solution was applied on the charge generation layer and dried with hot air at 100 ° C. for 60 minutes to form a charge transport layer having a thickness of 20 μm.

The photoreceptor manufactured in this way is inserted into the blade 1.1m.
m, mounted on a Canon copier NP-3525 modified to have a cleaning mechanism with a relative speed of the sponge roller of 102%, and the durability was evaluated. No blurring occurred even after the durability test of 100,000 sheets. A good quality copy was obtained. At this time, the amount of reduction in the thickness of the photoreceptor was 1.5 μm. Using another photoreceptor manufactured in the same manner, continuous copying of 5,000 sheets was performed, and the photoreceptor was left in a copying machine for 3 days, and the surface potential was measured. At this time, the portion of the photoreceptor located immediately below the corona charger during the standing was marked, and the potential difference (ΔV _D ) from the other portions was determined, but no difference was found.

Examples 2 to 16 below, as a lubricant powder, vinylidene fluoride resin powder,
Ethylene difluoride dichloride resin powder, polyethylene powder,
Using carbon fluoride as a charge transport material, the above CT-1 has an oxidation potential of 0.54 V, structural formula (5) (abbreviated as CT-2), oxidation potential of 0.4
A 7V compound of the structural formula (6) (abbreviated as CT-3) The compound corresponding to the general formula (1) is HB
Table 2 summarizes the results of the same evaluation as in Example 1 for a photoreceptor manufactured using the compounds shown in Table 1 in addition to CY-1.

Examples 17 to 20 Table 2 shows the evaluations of the photoconductors manufactured in the same manner as in Example 1 except that the amount of the compound represented by the general formula (1) was changed.

Comparative Examples 1 to 11 Photoreceptors lacking the lubricant powder or the compound represented by the formula (1) were produced from the compositions of the examples, and evaluated in the same manner as in the example 1.

In addition, Table 5 shows the evaluation results of the photoconductors using the charge transporting substances having an oxidation potential of 0.6 V or more shown in Table 3 and the photoconductors using other additives shown in Table 4.

As shown in Table 5, the photoreceptor to which the compound represented by the general formula (1) was not added and the photoreceptor to which an organic compound having a structure other than the compound represented by the general formula (1) was added, Blurring occurred from about 4000 sheets, and the image was indistinguishable after 100,000 sheets of durability test.

Also, the photoreceptor without the addition of the tetrafluoroethylene resin powder, which is a lubricating powder, has a sharp decrease in film thickness on the surface of the photoreceptor due to the durability test. Was in a state where it was difficult to distinguish it from characters.

The photoreceptor using a charge transport material having an oxidation potential of 0.6 V or more did not blur during the durability test, but when left in a copying machine for 3 days, the potential of the portion under the charger was significantly reduced. White spots occurred on the image.

Example 21 In the same manner as in Example 1, up to the undercoat layer was coated on an 80φ cylinder substrate.

Next, the hydrazone compound (CT-1) 15 used in Example 1 was used.
Parts, polycarbonate Z resin 10 parts dichloromethane 50
And a solution dissolved in 10 parts of monochlorobenzene was applied onto the undercoat layer to form a charge transport layer having a thickness of 15 μm.

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

Next, ethylene tetrafluoride resin powder, a fluorinated acrylic oligomer as a dispersant, a hydrazone compound (CT-1),
A polycarbonate Z resin was prepared. First, 10 parts of a polycarbonate resin, 4 parts of a hydrazone compound, and 0.15 part of a fluorinated acrylic oligomer are dissolved in 10 parts of dichloromethane and 40 parts of monochlorobenzene. Then, 1.5 parts of polytetrafluoroethylene resin powder was added thereto, and the mixture was dispersed in a stainless steel ball mill for 40 hours. Further, 0.3 part of the compound represented by the general formula (1) used in Example 1 was added to this liquid to prepare a charge transport layer liquid. A paint in which the charge generation layer dispersion liquid and the charge transport layer liquid were mixed at a ratio of 1: 1 was applied on the charge transport layer to form a charge generation layer having a thickness of 5 μm.

The copier used in Example 1 was modified so that it could be further positively charged, and this photoreceptor was evaluated in the same manner as in Example 1. However, even after the 100,000-sheet durability test, no blurring occurred and a high-quality copy was obtained. I got it. At this time, the amount of decrease in the thickness of the photoconductor is 2.5 μm.
m. The potential difference ([Delta] V _D) is almost observed no white spot with other portions in the portion even when left the endurance test after the photoreceptor in the copying machine hits the site just below the charger did not occur.

Comparative Example 12 As a comparative example of Example 21, a photoreceptor to which the compound represented by the general formula (1) was not added was manufactured and subjected to the same evaluation, but blurring began to occur from about several thousand sheets.

[Effects of the Invention] As described above, the electrophotographic photoreceptor containing the lubricant powder of the present invention, a charge transporting substance having an oxidation potential of less than 0.6 V, and an organic compound (additive) having a specific structure is mechanically The durability and the stability of the potential in a corona discharge environment are extremely high, and a stable high-quality image can always be obtained.
Further, the electrophotographic photoreceptor of the present invention can be used as a photoreceptor of a printer to which electrophotography is applied, such as a laser beam printer, an LED printer, an LCD printer, and a CRT printer, in addition to a normal copying machine.

Continuation of the front page (56) References JP-A-1-230052 (JP, A) JP-A-1-230053 (JP, A) JP-A-63-61256 (JP, A) JP-A-63-85748 (JP) , A)

Claims (5)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein at least the layer farthest from the support comprises a lubricant powder, a charge transporting substance having an oxidation potential of less than 0.6 V, and An electrophotographic photoreceptor comprising a compound represented by the formula (1). General formula (1) [Where R is And X ₁ is X ₂ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms 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 composed 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 comprising a charge generation layer and a charge transport layer, and the charge generation layer is provided on the charge transport layer. 4. The electrophotographic photosensitive member 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 carbon fluoride powder.