JPH03196049A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor that simultaneously contains a disazo pigment with a specific structure and oxytitanium phthalocyanine as a charge generating substance, and The present invention relates to an electrophotographic photoreceptor containing a stilbene compound with a specific structure and a triphenylamine compound as a transport substance.

[Prior Art] Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components are well known.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene; low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, and polyarylalkane; or phthalocyanine pigments; Organic pigments or dyes such as azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, and methine squaric acid dyes are known.

In particular, organic pigments and dyes with photoconductivity are easier to synthesize than non-contact materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. Conductive organic pigments and dyes have been proposed.

For example, US Pat. No. 4,123,270, US Pat. No. 4,247,614, US Pat. No. 4,251,613, US Pat. No. 4,251,614, US Pat. No. 4,256,821, US Pat. No. 4,260,672.
US Pat. No. 4,268,596, US Pat. No. 4,278,747 and US Pat. No. 42,936
As disclosed in the specification of No. 28, etc., an electrophotographic photoreceptor is known that uses a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer. There is.

An electrophotographic photoreceptor using such an organic photoconductor can be produced by coating by appropriately selecting a binder, and therefore has extremely high productivity and, as a result, can be provided at low cost. Moreover, it has the advantage that the sensitive wavelength range can be freely controlled by selecting the organic pigments and dyes used.

By the way, in recent years, with the advent of analog-digital dual-purpose machines or analog full-color copying machines that can perform exposure with a laser beam in addition to normal white light exposure, photoreceptors for copying machines have expanded from the visible range to the infrared range. There is a growing demand for sensitivity over a wide range of wavelengths.

However, since it is difficult to cover this wide wavelength range with a single charge-generating material, it has been proposed to use two or more types of charge-generating materials in combination. However, conventional photoreceptors made of a combination of two or more types of charge-generating substances have not yet achieved sufficiently excellent sensitivity and electrophotographic properties.

[Problems to be Solved by the Invention] The purpose of the present invention is to improve the above-mentioned drawbacks, to provide a material that has high sensitivity in a wide wavelength range from the visible light region to the infrared light (laser) region, and has excellent electrophotographic characteristics. An object of the present invention is to provide an electrophotographic photoreceptor.

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention provides an electroconductive support having a laminated or single-layer photosensitive layer containing at least both a charge-generating substance and a charge-transporting substance on a conductive support. In a photographic photoreceptor, two specific types of pigments are simultaneously contained as a charge generating substance, and a specific compound is also used as a charge transporting substance.

That is, the object of the present invention is achieved by the electrophotographic photoreceptor of the following (1) and/or (2) = (1) a conductive support containing at least a charge generating substance and a charge transporting substance. In an electrophotographic photoreceptor having a laminated or single layer photosensitive layer, the following structural formula [1] is used as a charge generating substance.
simultaneously contains a disazo pigment and an oxotitanium phthalocyanine, and the charge transport substance has the following structural formula [2
] and a triarylamine compound represented by the following structural formula [3].

(2) Bragg angle 2θ±0.2° in the Cu-α X-ray diffraction spectrum of oxotitanium phthalocyanine
are 7.4°, 9.2°, 10.4°, 11.6°1
3.0° 14.3′″ 15.0°, 15.
5°, 23.4°24.1', 26.2' and 2
The electrophotographic photoreceptor according to claim 1, which is an oxotitanium phthalocyanine crystal having a strong peak at 7.2°.

Structural formula [2] (Here, Ar', Ar'', Ar'' and Ar' represent a phenyl group, tolyl group or ethylphenyl group, and Ar'' and Ar' may be bonded to each other to form a ring. ) Ar' \ N--Ar' Structural formula [3] (Here, Ar' and Ar' represent a phenyl group, a tolyl group, or an ethylphenyl group, and Ar' is a phenyl group,
Represents a diphenyl group, a fluorenyl group, or a pyrenyl group. ) Specific examples of charge transport materials represented by structural formulas [2] and [3] are shown on the next page.

Structural formula [3] According to the present invention, the structural formula [3] exhibits high sensitivity in the visible light region.
Since it contains both the disazo pigment represented by [1] and oxotatinium phthalocyanine, which has high sensitivity in the infrared laser region, as charge-generating substances, it efficiently generates charges from light in the visible light region to the infrared light region. can be generated.

Several crystal forms are known for oxotatinium phthalocyanine, including amorphous, but among these, C
Bragg angle 2θ in the X-ray diffraction spectrum of α to u-
±0.2@7.4° 9.2°1O04° 11
．． 6° 13.0° 14.3" 15.0° Those with strong peaks at 15.5°, 23.4°, 24.1°, 26.2° and 27.2" are very Since it exhibits high sensitivity, it can be said to be a preferable crystal form.

In addition, by containing the stilbene compound of structural formula [2] or the triphenylamine compound of structural formula [3], which exhibits optimal compatibility with both disazo pigments and oxotatinium phthalocyanine, as a charge transport material, Since the charged charges can be efficiently transported, it is possible to provide a photoreceptor with extremely high sensitivity from the visible region to the infrared region.

In addition, both the disazo pigment of structural formula [1] and the oxotatinium phthalocyanine inherently have the property that there is little decrease in potential after a history of light irradiation, little increase in bright area potential, and little decrease in dark area potential after repeated durability tests. However, in the present invention, since charge transport materials that are optimally compatible with each other are used as both charge generation materials, their characteristics can be utilized in a manner that takes advantage of each other.

In addition, even if these two charge-generating substances are mixed and placed in a coexisting state, they do not create carrier trap sites or barriers, so that the mixing does not cause deterioration of characteristics.

Therefore, the photoreceptor of the present invention has excellent potential stability, and is a photoreceptor with a long life that can stably form high image quality compared to photoreceptors for digital and analog dual-use machines obtained by combining conventional materials. can.

In addition, the charge generating substance is dispersed in a solvent together with a binder, and a film is formed by coating the dispersion, but both of the charge generating substances used in the present invention have dispersibility. It is excellent in that a stable coating liquid (coating liquid) can be formed without causing any adverse effects such as aggregation even when mixed.

Therefore, the photoreceptor of the present invention obtained using the coating liquid has excellent productivity.

Next, specific embodiments of the electrophotographic photoreceptor of the present invention will be explained.

The photosensitive layer is provided on a substrate having a conductive layer, ie, a conductive support. As the substrate having a conductive layer, a substrate which itself is conductive is used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, and the like.

In addition, plastics having a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., conductive particles (e.g. carbon black, silver particles, etc.) with a suitable binder. In addition, a substrate coated on plastic or the like, a substrate obtained by impregnating plastic or paper with conductive particles, a plastic having a conductive polymer, etc. can be used.

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

The subbing layer can be formed from casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. .

The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably 0.1 to 10 μm.
It is 5 to 3 μm.

Furthermore, it is preferable to provide a conductive layer between the substrate and the undercoat layer for the purpose of covering unevenness and defects on the substrate and preventing interference fringes caused by scattering of laser light when the image input is a laser beam. This can be formed by dispersing conductive powder such as carbon black, metal particles, metal oxide, etc. in a binder resin described later.

The thickness of the conductive layer is usually 5 to 401 tm, preferably 10 to 3 tm.
0ILm.

The photosensitive layer may take either a single layer type in which a charge generating substance and a charge transporting substance are contained in the same layer, or a laminated type in which a charge generating layer and a charge transporting layer are arranged in a separated state. Also,
In the case of a laminated type, whether a charge generation layer is provided on the substrate side or a charge transport layer is provided on the substrate side,
Similarly, the effects of the present invention can be obtained.

In order to provide a charge generation layer containing two types of pigments simultaneously in a photoreceptor having a laminated type photosensitive layer, the two types of pigments are dispersed in a resin solution, or the liquids in which they are individually dispersed are mixed. This can be done by applying a coating liquid obtained by

In this case, the ratio of oxotitanium phthalocyanine to the disazo pigment of structural formula [1] is former/latter = lO/l
A range of -1/2 is preferred. The purpose is to minimize the wavelength dependence of sensitivity.

Further, the thickness of the charge generation layer is 0.01 to 10 μm, preferably 0.05 to 3 μm.

The resin used can be selected from a wide range of insulating resins and also from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (condensation polymer of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyrrolidine, cellulose resin, urethane resin, Examples include insulating resins such as epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone.

The amount of resin contained in the charge generation layer is usually less than % by weight,
It is preferably selected to be 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of target resin, and is preferably selected from those that do not dissolve the charge transport layer or undercoat layer, which will be described later.

Specific organic solvents include methanol, ethanol,
Alcohols such as isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexane, N, N-
Amides such as dimethylformamide, N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, methyl acetate,
Esters such as ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, dichlorobenzene, etc. Hydrocarbons etc. can be used.

The charge transport layer is prepared by dissolving or dispersing a stilbene compound of structural formula [2] or a triphenylamine compound of structural formula [31] in a solvent together with a binder resin as described in the section for the charge generation layer to obtain a coating solution. , can be formed by applying this.

The thickness of the charge transport layer is generally set to 5 to 30 μm, preferably 8 to 20 μm.

The weight ratio of the stilbene compound and the binder resin is set to the former/latter ratio of 1/3 to 3/1, preferably 1/2 to 2/l.

In order to provide a single-layer photosensitive layer containing a charge-generating substance and a charge-transporting substance in the same layer, basically two kinds of charge-generating substances and a stilbene compound of structural formula [2] or a stilbene compound of structural formula [2] are combined.
This can be carried out by dispersing the triphenylamine compound (3) in a solution of a binder resin as described in the section regarding the laminated charge generation layer to obtain a coating solution, and then coating the solution.

In this case, the ratio of the disazo pigment represented by the structural formula [1] and the oxotitanium phthalocyanine is the former/latter = 6/l to 1/2 on a weight basis, as in the above-mentioned charge generation layer section.
is preferred.

Further, the weight ratio between the total amount of charge generating substances and the stilbene compound represented by structural formula [2] is former/latter = 1/2
0 to 5/1 is preferred.

When a single photosensitive layer is provided, the amount of resin contained in the layer is preferably 75 to 25% by weight. Also, the film thickness is usually 5 to 4
0 μm, preferably 10 to 30 μm.

In the present invention, a single-layer photoreceptor or an electrophotographic photoreceptor having a laminated photosensitive layer in which a charge generating substance and a charge transporting substance are contained in separate layers has been described. It can be easily imagined from the results of the present invention that a photoreceptor manufactured by laminating layers having different ratios using a charge transporting substance can also exhibit the same effects as the present invention.

Regarding the formation of each layer by these coatings, a known coating method such as a dipping method, a spray method, a beam method, a blade coating method, or a spinner coating method can be used.

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

Example 1 A cylinder having an outer diameter of 80 mm and a length of 360 mm was used as a base. A conductive layer made of the following material was coated onto the substrate by a dipping method and thermally cured at 140° C. for 30 minutes to form an anti-scattering conductive layer with a thickness of 18 μm.

(Chromes ECT-62 manufactured by Titanium Industries) (Titone 5R-IT manufactured by Sakai Chemicals) (J-325 manufactured by Dainippon Ink) Next, polyamide resin [Product name: Amilan CM-8000
(manufactured by Toshisha Co., Ltd.) by a dipping method to form a subbing layer having a thickness of 1 μm.

Next, 10 parts by weight of the disazo pigment represented by the structural formula [1], 4 parts by weight of oxotitanium phthalocyanine crystal powder showing the X-ray diffraction spectrum according to claim 2, and polyvinyl butyral resin [trade name: Eslec BX-1] (
7.5 parts by weight, 150 parts of MEK, and 200 parts of cyclohexanone were mixed and dispersed for 10 hours in a sand mill containing glass beads with a diameter of 1 mm, and then diluted appropriately to obtain a coating solution for forming a charge generation layer. And so.

This coating liquid was applied onto the undercoat layer using a dipping method to form a film with a film thickness of 0.15.
A charge generation layer of .mu.m was formed.

Next, a stilbene compound represented by the above structural formula [2] (
A coating solution for forming a charge transport layer is prepared by dissolving 10 parts of compound N (L, 2) and 10 parts of bisphenol Z type polycarbonate resin (manufactured by Mitsubishi Gas Chemical) in a mixed solvent consisting of 50 parts of monochlorobenzene and 10 parts of dichloromethane. And so.

This coating solution was applied onto the charge generation layer using a dipping method, and the film thickness was 2.
A charge transport layer of 6 μm was formed.

Example 2 A trianolamine compound (compound An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that fish 5) was used.

Example 3 2 parts by weight of the disazo pigment represented by the structural formula [1],
1 part by weight of powder of oxotitanium phthalocyanine crystal exhibiting the X-ray diffraction spectrum according to claim 2, a stilbene compound represented by the structural formula [3] (compound NQ,
, 6) 12 parts by weight, 15 parts by weight of the polyvinyl butyral resin described in Example 1, methyl ethyl ketone (MEK
) and 100 parts by weight of cyclohexanone were mixed and dispersed for 10 hours in a sand mill containing glass beads having a diameter of 1 mm to prepare a coating liquid.

This coating solution was coated at A°C with the undercoat layer installed as described in Example 1.
Coated on the undercoating layer of the cylinder by dipping method to a thickness of 15 μm.
A photosensitive layer of m was formed.

Example 4 An anti-scattering conductive layer and a subbing layer were provided on an AI2 cylinder in the same manner as described in Example 1. Next, a coating solution for forming a charge transport layer prepared in the same manner as described in Example 1 was applied onto the undercoat layer by a dipping method to form a charge transport layer with a thickness of 18 μm. . Next, a coating solution for forming a charge generation layer prepared in the same manner as described in Example 1 was applied onto the charge transport layer by a spray method to form a charge generation layer having a thickness of 3 μm.

Comparative Example 1 No implementation except that the oxotitanium phthalocyanine crystal powder having the X-ray diffraction spectrum according to claim 2 used in the charge generation layer in Example 1 was changed to an azo pigment represented by the following structural formula [4]. An electrophotographic photoreceptor was produced in the same manner as in Example 1.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the stilbene compound of the structural formula [2] used in the charge transport layer in Example 1 was changed to a triphenylamine compound represented by the following structural formula [5]. An electrophotographic photoreceptor was produced.

Structural formula [5] The electrophotographic photoreceptors produced according to Examples 1 to 3 and Comparative Examples 1 to 2 were tested using a copying machine [NP-4835 (Canon ■
Sensitivity in the visible light region and infrared region, repetition characteristics, and photomemory were evaluated using the following products. Example 2
When evaluating photoreceptors No. 3 and No. 3, modifications were made so that the polarity of charging was reversed.

Note that this copying machine uses semiconductor laser exposure to perform static elimination exposure after the cleaning process and to input arbitrary character patterns that are not on the original.

Sensitivity in the visible light region is determined by using a halogen lamp and determining the exposure amount [E (1/2)
βux-sec] was evaluated. In addition, the sensitivity in the infrared light region is determined by the amount of energy [E (1/2. λ = 780 nm) μJ/cm] required for the dark potential to attenuate to 172 using a 780 nm semiconductor laser.
] was evaluated by measuring.

In the above measurements, the dark potential was set to 650V.

Next, in order to evaluate the repetition characteristics, 100
A 0-frame image was produced, and the difference [ΔV, ] between the dark area potential after image exposure and the dark area potential before image exposure was measured.

Next, each photoreceptor is irradiated with light of 1500βux, and the difference between the dark area potential after irradiation and the dark area potential before light irradiation [Δv p,]
was measured to evaluate photomemory.

The above results are summarized in Table 1.

Table *2 *3 *4 *5 2 Same as above〃 Same as above: Same as above / Same as above: Charge transport layer〃Charge generation layer: About 2 disazo pigments〃Charge transport layer＊6: Charge generation layer〃Special triarylamine (stilbene) [Effects of the Invention] As is clear from the above results, the electrophotographic photoreceptor of the present invention has high sensitivity in both the visible light region and the infrared laser region, and has a small photomemory (the value of ΔV py). It can be seen that the repeatability is excellent.

Claims (2)

[Claims] (1) Electrophotography having a single-layer photosensitive layer on a conductive support, in which at least a charge-generating substance and a charge-transporting substance are contained in the same layer, or a laminated photosensitive layer in which both substances are contained in separate layers. In the photoreceptor, the charge generating substance contains both a disazo pigment represented by the following structural formula [1] and oxotitanium phthalocyanine, and the charge transporting substance is a stilbene compound represented by the following structural formula [2] and the following structure. Electrophotographic photoreceptor characterized by being a triphenylamine compound represented by formula [3]: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Structural formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Structural formula [2] ] (Ar^1, Ar^2, Ar^3 and Ar^4 represent a phenyl group, tolyl group, ethylphenyl group, and Ar^3
and Ar^4 may be bonded to each other to form a ring. ) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Structural formula [3] (Ar^5 and Ar^6 represent a phenyl group, tolyl group, ethylphenyl group, and Ar^7 represents a phenyl group, diphenyl group, fluorenyl group, or (Represents a pyrenyl group.) (2) Cu-K of oxotitanium phthalocyanine crystals
Bragg angle 2θ±0 in the X-ray diffraction spectrum of α.
2° is 7.4°, 9.2°, 10.4°, 11.6°,
13.0°, 14.3°, 15.0°, 15.5°, 2
Oxotitanium phthalocyanine crystals having strong peaks at 3.4°, 24.1°, 26.2° and 27.2° and 0.00° for the oxotitanium phthalocyanine crystals.
2. The electrophotographic photoreceptor according to claim 1, further comprising 01 to 50% by weight of metal-free phthalocyanine.