JPH09281734A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance sensitivity higher than the conventional ones by incorporating α-oxotitanylphthalocyanine having a crystallinity of a specified value or more as a charge generating agent in a photosensitive layer. SOLUTION: The photosensitive layer contains as the charge generating agent the α-oxotitanylphthalocyanine having a crystallinity Y of >=15 measured by using a characteristic X-ray of Cu, CuK having a wavelength of 1.541Å as a light source and the expression: Y=(A+B)/B, where A is diffraction line strength at a diffraction peak at a Bragg angle of 7.6 deg.±0.3 deg. and B is a background line strength at the same angle. The X-ray diffraction peaks exist in addition at Bragg angles (2θ) of near 7.6 deg., 10.4 deg., 12.8 deg., 13.5 deg., and 14.5 deg., and the like. The sensitivity characteristics can be enhanced by using the α- oxotitanylphthalocyanine having a high crystallinity of >=15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic copying machine,
The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus such as a laser printer or a plain paper facsimile machine.

[0002]

2. Description of the Related Art Organic photoconductors are widely used in the above image forming apparatus. Organic photoconductors are easier to manufacture than inorganic photoconductors that use inorganic semiconductor materials, and there are various choices of materials such as charge generation agents, charge transport agents, and binder resins, which gives flexibility in functional design. Has the advantage of being large.

As such an organic photoreceptor, for example, one having a single-layer type photosensitive layer in which a charge generating agent which generates an electric charge by light irradiation is dispersed in a binder resin together with a charge transfer agent which transfers the generated electric charge, Alternatively, a charge-generating layer containing the above charge-generating agent and a charge-transporting layer containing a charge-transporting agent are laminated to form a laminated photosensitive layer.

As the charge generating agent used in the above-mentioned organic photoreceptor, various pigments are used depending on the sensitivity range of the photoreceptor. For example, an infrared or near infrared ray such as a semiconductor laser or an infrared LED is used. Phthalocyanine pigments are widely used as charge generating agents for photoconductors that are sensitive to wavelength light. The phthalocyanine-based pigment includes metal-free phthalocyanine, oxotitanyl phthalocyanine, etc. depending on its structure, and each of them can have various crystal types, so that various crystal types can be used in order to improve characteristics as a charge generating agent. Are being considered.

[0005]

Problems to be Solved by the Invention For example, Japanese Patent Publication No. 6-2
In Japanese Patent Publication No. 9975 and Japanese Patent Publication No. 6-29976, oxotitanyl phthalocyanine having an α-type crystal form is superior in characteristics as a charge generating agent to those having other crystal types, and therefore, is a single-layer type. Alternatively, it has been shown that it can contribute to improving the sensitivity of a laminated electrophotographic photoreceptor.

However, according to the studies by the inventors, the conventional photoconductor using the α-type oxotitanyl phthalocyanine as the charge generating agent has excellent characteristics as the charge generating agent that the α-type oxotitanyl phthalocyanine has. Has not been fully utilized, and it has become clear that there is room for further improvement in sensitivity. An object of the present invention is to provide an electrophotographic photosensitive member which uses α-type oxotitanyl phthalocyanine as a charge generating agent and has further improved sensitivity as compared with the conventional one.

[0007]

According to the studies made by the inventors, the α-type oxotitanyl phthalocyanine used in the conventional photoconductor is the characteristic X-ray of copper.

[0008]

[Outside 2]

Among the X-ray diffraction spectra measured with the (wavelength 1.541Å) as the radiation source, as shown in FIG. 1, the diffraction line intensity of the diffraction peak at the Bragg angle (2θ) of 7.6 ± 0.3 °. When A and the valleys on both sides sandwiching this diffraction peak are connected by a common tangent line indicated by a dashed line in the figure, the intensity B of this tangent line at the same Bragg angle as the above diffraction peak
From the background diffraction line intensity represented by
(1):

[0010]

[Equation 2]

The crystallinity Y calculated by
Since it is as low as about 4 to 4, it has been clarified that the excellent characteristics of the α-type oxotitanyl phthalocyanine as a charge generating agent are not fully utilized. For example, the crystallinity Y of the α-type oxotitanyl phthalocyanine used in the above-mentioned prior art is described in Japanese Patent Publication No. 6-2997.
From the X-ray diffraction spectrum shown in FIG.
It was about 3.48 as determined by the above method.

On the basis of this finding, the excellent crystallinity of α-type oxotitanyl phthalocyanine as a charge generating agent can be fully utilized, and a crystallinity with which a photoreceptor having a higher sensitivity than that of the conventional one can be obtained. As a result of further examination of the range, the present invention has been completed. That is, in the electrophotographic photoreceptor of the present invention, the crystallinity Y determined by the above formula (1) as a charge generating agent is 1 in the photosensitive layer.
It is characterized by containing α-type oxotitanyl phthalocyanine of 5 or more.

The α-type oxotitanyl phthalocyanine having a crystallinity Y of 15 or more, which is used as a charge generating agent in the electrophotographic photosensitive member of the present invention having the above-mentioned constitution, is used in Examples and Comparative Examples described later. As is clear from the results, it is possible to dramatically improve the sensitivity of the photoconductor as compared with the case where the crystallinity Y is less than 15. It is considered that this is because the charge generation efficiency is significantly improved as the crystallinity increases.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below. The oxotitanyl phthalocyanine used as the charge generating agent in the present invention has an α-type crystal form as described above. That is, the characteristic X-ray of copper

[0015]

[Outside 3]

Of the X-ray diffraction spectra measured with the (wavelength 1.541Å) as a radiation source, the Bragg angle (2θ)
7.6 °, 10.4 °, 12.8 °, 13.5 °, 1
5.4 °, 16.5 °, 17.5 °, 18.6 °, 2
Oxotitanyl phthalocyanine having strong diffraction peaks in the vicinity of 2.8 °, 24.5 °, 25.7 ° and 29.2 ° is used.

The α-type oxotitanyl phthalocyanine used in the present invention has the above-mentioned X-type as shown in FIG.
Bragg angle (2θ) of the line diffraction spectrum of 7.6
When the diffracted line intensity A of the diffractive peak of 7.6 ± 0.3 ° and the valleys on both sides of this diffracted peak are connected by a common tangent line shown by a dashed line in the figure From the background diffraction line intensity represented by the intensity B of this tangent line at the same Bragg angle as the above diffraction peak,
(1):

[0018]

(Equation 3)

It is necessary that the crystallinity Y determined by the above is 15 or more. The reason is as described above.
The crystallinity Y is, considering the sensitivity of the photoconductor,
Even within the above range, it is particularly preferably 23 or more. The electrophotographic photosensitive member of the present invention is one in which the photosensitive layer containing the α-type oxotitanyl phthalocyanine having the crystallinity Y of 15 or more as the charge generating agent is provided on the conductive substrate. As described above, the photosensitive layer includes so-called single-layer type photosensitive layer and laminated type photosensitive layer, but the present invention is applicable to both of them.

The single-layer type photosensitive layer is prepared by dissolving or dispersing α-type oxotitanyl phthalocyanine, which is a charge generating agent, in a suitable solvent together with a charge transporting agent and a binder resin by a means such as coating. It is formed by coating on a conductive substrate and drying. Such a single-layer type photosensitive layer has a simple layer structure and is excellent in productivity. As the charge transfer agent, either one or both of an electron transfer agent and a hole transfer agent can be used. In particular, the single-layer type photosensitive layer in which both the transfer agents are used in combination has a positive or negative charge in a single constitution. There is an advantage that it can correspond to.

The electron transfer material and the hole transfer material each have a good matching with α-type oxotitanyl phthalocyanine, which is a charge generating agent, and can extract electrons or holes generated in the α-type oxotitanyl phthalocyanine to efficiently remove them. Those that can be transported well are desirable. Further, in a system in which an electron transfer material and a hole transfer material coexist, both prevent formation of a charge transfer complex, which causes a decrease in charge transfer ability in the entire photosensitive layer and a decrease in sensitivity of the photoreceptor. Therefore, it is necessary to consider the combination of both transport agents. That is, even if both transfer agents are contained in the same layer at a high concentration at which hole transport and electron transport are efficiently performed, a charge transfer complex is not formed in the layers, and the hole transport agent transports holes to electron transport. As the agent, it is desirable to select a combination of an electron transporting agent and a hole transporting agent that can transport electrons efficiently.

On the other hand, in the laminated type photosensitive layer, first, a charge generating layer containing α-type oxotitanyl phthalocyanine which is a charge generating agent is formed on a conductive substrate by means such as vapor deposition or coating, and then the charge generating layer is formed. The charge transport layer is formed by applying a coating solution containing a charge transport agent and a binder resin onto the generating layer by means such as coating and drying the coating solution. In contrast to the above, a charge transport layer may be formed on the conductive substrate, and the charge generation layer may be formed thereon.

However, since the charge generating layer is much thinner than the charge transporting layer, the charge generating layer is formed on the conductive substrate and the charge transporting layer is formed thereon for protection thereof. Is preferred. The lamination type photosensitive layer is selected from positive and negative charging types depending on the order of forming the charge generation layer and the charge transport layer and the type of the charge transport agent used in the charge transport layer.

For example, in the layer structure in which the charge generating layer is formed on the conductive substrate and the charge transporting layer is formed thereon, when the hole transporting agent is used as the charge transporting agent of the charge transporting layer, , The photosensitive layer is of negative charging type. In this case, the charge generation layer may contain an electron transport agent. As the electron transfer agent contained in the charge generation layer, it is desirable that the electron transfer agent has good matching with α-type oxotitanyl phthalocyanine which is a charge generation agent and can efficiently transport the electrons generated by the α-type oxotitanyl phthalocyanine.

On the other hand, in the above-mentioned layer structure, when the electron transfer agent is used as the charge transfer agent of the charge generation layer, the photosensitive layer becomes positively charged. In this case, the charge generation layer may contain a hole transporting agent. As the electron-transporting agent used in the above-mentioned single-layer type or laminated-type photosensitive layer, any of various conventionally known electron-transporting compounds can be used. In particular, benzoquinone-based compounds, diphenoquinone-based compounds, and naphthoquinone. Compounds, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, fluorenone compounds [eg 2,4,7-trinitro-9-fluorenone, etc.],
Dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2,4,7-trinitrofluorenoneimine type compound, ethylated nitrofluorenoneimine type compound, tryptoanthrine type Compounds, tryptoanthrin imine compounds, azafluorenone compounds, dinitropyridquinazoline compounds,
Thioxanthene compounds, 2-phenyl-1,4-benzoquinone compounds, 2-phenyl-1,4-naphthoquinone compounds, 5,12-naphthacenequinone compounds, α
Various electron-withdrawing compounds such as -cyanostilbene compounds, 4'-nitrostilbene compounds, and salts of benzoquinone compounds with anion radicals and cations are preferably used. These can be used alone or in combination of two or more.

Among them, especially the general formula (ET1):

Embedded image

[Wherein R ^e1 , R ^e2 , R ^e3 and R ^e4 are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or The aryl group which may have a substituent is shown. ] The diphenoquinone-based compound represented by the following is preferably used as an electron transfer agent having good matching with the α-type oxotitanyl phthalocyanine and excellent electron transfer ability.

As the hole-transporting agent, any of various conventionally known hole-transporting compounds can be used. In particular, benzidine compounds, phenylenediamine compounds,
Naphthylenediamine compounds, phenanthrylenediamine compounds, oxadiazole compounds [eg 2,
5-di (4-methylaminophenyl) -1,3,4-oxadiazole, etc.], a styryl compound [for example, 9-
(4-diethylaminostyryl) anthracene, etc.], a carbazole compound [eg poly-N-vinylcarbazole etc.], an organic polysilane compound, a pyrazoline compound [eg 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline etc.], Hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds,
Butadiene-based compounds, pyrene-hydrazone-based compounds, acrolein-based compounds, carbazole-hydrazone-based compounds, quinoline-hydrazone-based compounds, stilbene-based compounds, stilbene-hydrazone-based compounds, and diphenylenediamine-based compounds are preferably used. These can be used alone or in combination of two or more.

Among them, especially the general formula (HT1):

[0030]

Embedded image

[In the formula, R ^h1 , R ^h2 , R ^h3 , R ^h4 , R ^h5 and R ^h6 are the same or different and each represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group or a substituent. The alkoxy group which may have or the aryl group which may have a substituent is shown. a and b are the same or different and are 1 to 4
, And c, d, e and f are the same or different and each represents an integer of 1 to 5. When a, b, c, d, e or f is 2 or more, each R ^h1 , R ^h2 , R ^h3 , R ^h4 , R ^h5
And R ^h6 may be different. ] The benzidine type compound represented by or general formula (HT2):

[0032]

Embedded image

[Wherein, R^h7, R^h8, R^h9, R^h10and
R^h11Are the same or different and are hydrogen atom,
Child, an alkyl group which may have a substituent, and a substituent
Which may have an alkoxy group or a substituent,
Group. g, h, i and j are the same or different
Represents an integer of 1 to 5, and k represents an integer of 1 to 4. What
When g, h, i, j or k is 2 or more, each R^h7,
R^h8, R^h9, R^h10And R ^h11Can be different
Yes. ] The phenylenediamine compound represented by
Matches well with α-type oxotitanyl phthalocyanine
Suitable as a hole-transporting agent having excellent hole-transporting ability
Used for.

Examples of the halogen atom corresponding to each group in the general formulas representing the electron transfer agent and hole transfer agent include fluorine atom, chlorine atom, bromine atom, iodine atom and the like. As the alkyl group, for example, a methyl group,
C1-C6 such as ethyl group, normal propyl group, isopropyl group, normal butyl group, isobutyl group, secondary butyl group, tertiary butyl group, pentyl group, hexyl group
And lower alkyl groups.

Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, a butoxy group and a tertiary group.
Examples thereof include a butoxy group and a hexyloxy group. Examples of the aryl group include a phenyl group, a biphenyl group,
Examples thereof include naphthyl group, anthryl group, phenanthryl group and o-terphenyl group. Examples of the aralkyl group include benzyl group, benzhydryl group, trityl group, phenethyl group and the like.

Further, examples of the substituent which may be substituted on these groups and the phenoxy group include the above-mentioned alkyl group, halogen atom or alkoxy group. Examples of the binder resin include styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic polymers, styrene-acrylic copolymers, polyethylene, ethylene. −
Vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallylphthalate resin, ketone resin, polyvinyl butyral Thermoplastic resins such as resins and polyether resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins and other crosslinkable thermosetting resins, and photocurable resins such as epoxy-acrylate and urethane-acrylate. Can be given. These binder resins can be used alone or in combination of two or more.

In the photosensitive layer, in addition to the above components, for example, a sensitizer, a fluorene compound, an ultraviolet absorber, a plasticizer,
Various additives such as an interfacial lubricant and a leveling agent can also be added. In order to improve the sensitivity of the photoconductor,
For example, a sensitizer such as terphenyl, halonaphthoquinones and acenaphthylene may be used in combination with the charge generating agent. Further, another charge generating agent may be used in combination for adjusting the sensitivity region of the photoconductor. Other charge generating agents include, but are not limited to, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, powders of inorganic photoconductive materials such as α-silicon, azo pigments, bisazo pigments, perylene pigments. , Anthanthrone-based pigments, conventional phthalocyanine-based pigments other than α-type oxotitanyl phthalocyanine having a crystallinity Y of 15 or more, indigo-based pigments, triphenylmethane-based pigments, slene-based pigments, toluidine-based pigments, pyrazoline-based pigments, Examples thereof include quinacridone pigments and dithioketopyrrolopyrrole pigments. These other charge generating agents may be used alone or in combination of two or more.

In the laminated type photoreceptor, the charge generating agent and the binder resin constituting the charge generating layer can be mixed in various proportions, and the charge generating agent is added to 100 parts by weight of the binder resin. 5 to 1000 parts by weight, especially 30 to 500 parts by weight is preferably blended. Note that, when the α-type oxotitanyl phthalocyanine is used alone as the charge-generating agent, the amount of the charge-generating agent is the amount of the α-type oxo-titanyl phthalocyanine, and α-type oxo-titanyl phthalocyanine and other charge-generating agents When the agent is used in combination, the total amount is the total amount of both.

When the α-type oxotitanyl phthalocyanine is used in combination with another charge generating agent, it is preferable to add the other charge generating agent in a small amount within a range that does not impair the effects of the α-type oxotitanyl phthalocyanine described above. Specifically, another charge generating agent is used as α-type oxotitanyl phthalocyanine 1
It is preferable to add 30 parts by weight or less to 00 parts by weight.

The charge-transporting agent and the binder resin constituting the charge-transporting layer can be mixed in various proportions within a range that does not hinder the transport of charges and a range that does not crystallize. In order to easily transport the charge generated in step 1, one charge transfer agent is added to 100 parts by weight of the binder resin.
It is preferable to mix it in an amount of 0 to 500 parts by weight, particularly 25 to 200 parts by weight.

Regarding the thickness of the laminated type photosensitive layer, it is preferable that the charge generation layer is formed to have a thickness of about 0.01 to 5 μm, particularly 0.1 to 3 μm, and the charge transport layer has a thickness of 2 to 100 μm, particularly 5 to 5. The thickness is preferably about 50 μm. In the single-layer type photoreceptor, the charge generating agent is 0.1 to 50 parts by weight, particularly 0.5 to 30 parts by weight, and the charge transporting agent is 20 to 500 parts by weight, and particularly 100 to 100 parts by weight of the binder resin. 30-20
It is suitable to add 0 part by weight.

The amount of the above-mentioned charge generating agent is the same as that described above, when only the α-type oxotitanyl phthalocyanine of the present invention is used as the charge generating agent, it is the amount of the α-type oxotitanyl phthalocyanine. When the type oxotitanyl phthalocyanine and other charge generating agent are used in combination, the total amount is the total amount of both. When the α-type oxotitanyl phthalocyanine is used in combination with another charge generating agent, the other charge generating agent is preferably blended in a small amount within a range that does not impair the effects of the α-type oxotitanyl phthalocyanine described above. Specifically, it is preferable to add another charge generating agent in a proportion of 100 parts by weight or less with respect to 100 parts by weight of α-type oxotitanyl phthalocyanine.

When only one of an electron transporting agent and a hole transporting agent is used as the charge transporting agent, the charge transporting agent is blended with the electron transporting agent alone. When a transporting agent and a hole transporting agent are used in combination, the total amount of the two is blended. When the electron transfer agent and the hole transfer agent are used in combination, the electron transfer agent is preferably blended in a ratio of 10 to 100 parts by weight with respect to 100 parts by weight of the hole transfer agent.

The thickness of the single-layer type photosensitive layer is 5 to 100 μm,
It is particularly preferable that the thickness is about 10 to 50 μm. In the case of a photoreceptor having a single-layer type photosensitive layer, between the conductive base and the photosensitive layer, and in the case of a photoreceptor having a laminated type photosensitive layer, the conductive base and the charge generation layer are provided. A barrier layer may be formed between the electrically conductive substrate and the charge transport layer, or between the charge generation layer and the charge transport layer as long as the characteristics of the photoreceptor are not impaired. A protective layer may be formed on the surface of the photoreceptor having the single-layer type or laminated type photosensitive layer.

As the conductive substrate on which the above layers are formed, various conductive materials can be used.
For example, metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, and plastic materials obtained by vapor deposition or lamination of the above metals, iodine, Examples thereof include glass coated with aluminum oxide, tin oxide, indium oxide and the like.

The conductive substrate may have a sheet shape, a drum shape, or the like, depending on the structure of the image forming apparatus used. The substrate itself may be conductive, or the surface of the substrate may be conductive. In addition, the conductive substrate preferably has sufficient mechanical strength when used. When each layer constituting the photoreceptor is formed by a coating method, the charge generating agent, charge transporting agent, binder resin and the like exemplified above are used together with a suitable solvent in a known method,
For example, a roll mill, a ball mill, an attritor, a paint shaker or an ultrasonic disperser is used to disperse and mix to prepare a coating solution, which is coated by a known means.
Just dry.

As the solvent for forming the coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, Aromatic hydrocarbons such as benzene, toluene, xylene, dichloromethane, dichloroethane, carbon tetrachloride, halogenated hydrocarbons such as chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran,
Examples thereof include ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide and dimethyl sulfoxide. These solvents can be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the charge transport agent or the charge generating agent and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent or the like may be added to the coating liquid.

[0049]

The present invention will be described below with reference to examples and comparative examples. Example 1 As shown in FIG. 2, among the X-ray diffraction spectra measured using the characteristic X-ray of copper as the radiation source, the Bragg angle (2θ)
7.860 °, 10.540 °, 12.940 °, 1
3.580 °, 15.460 °, 16.600 °, 1
7.540 °, 18.720 °, 22.860 °, 2
It has strong diffraction peaks at 4.560 °, 25.700 ° and 29.020 °, and the diffraction line intensity A of the diffraction peak at the Bragg angle (2θ) of 7.860 °.
Based on the background diffraction line intensity B at the same Bragg angle (2θ) of 7.860 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 24.39 determined by the above formula (1) was used as a charge generating agent. Used as.

Then, 3 parts by weight of the above-mentioned oxotitanyl phthalocyanine, which belongs to the benzidine compound represented by the general formula (HT1) as a charge transport agent, is represented by the formula (HT1-1):

[0051]

Embedded image

A coating solution for a single-layer type photosensitive layer was obtained by mixing and dispersing in a ball mill together with 100 parts by weight of the compound represented by: 100 parts by weight of a binder resin, polycarbonate, and tetrahydrofuran. Then, the above coating solution,
It is applied using a wire bar on an aluminum substrate which is a conductive base material, and dried with hot air at 110 ° C. for 30 minutes,
An electrophotographic photoreceptor having a single-layer type photosensitive layer having a film thickness of 20 μm was produced.

Example 2 As shown in FIG. 3, of the X-ray diffraction spectra measured using the characteristic X-ray of copper as the radiation source, the Bragg angle (2θ)
7.660 °, 10.380 °, 12.740 °, 1
3.340 °, 15.280 °, 16.440 °, 1
7.400 °, 18.440 °, 22.660 °, 2
Diffraction line intensity A of the diffraction peak at the Bragg angle (2θ) of 7.660 ° while having strong diffraction peaks at 4.380 °, 25.520 ° and 28.760 °,
From the background diffraction line intensity B at the same Bragg angle (2θ) of 7.660 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 23.06 determined by the above formula (1) is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Example 3 As shown in FIG. 4, among the X-ray diffraction spectra measured using the characteristic X-ray of copper as the radiation source, the Bragg angle (2θ)
7.660 °, 10.420 °, 12.800 °, 1
3.400 °, 15.300 °, 16.480 °, 1
7.380 °, 18.520 °, 22.700 °, 2
Diffraction line intensity A of the diffraction peak of Bragg angle (2θ) 7.660 ° while having strong diffraction peaks at 4.400 °, 25.600 ° and 28.880 °,
From the background diffraction line intensity B at the same Bragg angle (2θ) of 7.660 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 20.68 determined by the above formula (1) is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Example 4 As shown in FIG. 5, the Bragg angle (2θ) in the X-ray diffraction spectrum measured using the characteristic X-ray of copper as the radiation source.
7.440 °, 10.120 °, 12.540 °, 1
3.160 °, 15.040 °, 16.220 °, 1
7.180 °, 18.300 °, 22.460 °, 2
Diffraction line intensity A having strong diffraction peaks at 4.160 °, 25.280 ° and 28.580 ° and the diffraction peak at the Bragg angle (2θ) of 7.440 °,
From the background diffraction line intensity B at the same Bragg angle (2θ) of 7.440 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 15.39 obtained by the above formula (1) is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Comparative Example 1 As shown in FIG. 6, the Bragg angle (2θ) in the X-ray diffraction spectrum measured using the characteristic X-ray of copper as a radiation source.
7.800 °, 10.480 °, 12.940 °, 1
3.560 °, 15.380 °, 16.620 °, 1
7.560 °, 18.680 °, 22.760 °, 2
Diffraction line intensity A of the diffraction peak at the Bragg angle (2θ) of 7.800 ° while having strong diffraction peaks at 4.500 °, 25.580 ° and 28.820 °,
Based on the background diffraction line intensity B at the same Bragg angle (2θ) of 7.800 °, α-type oxotitanyl phthalocyanine having a crystallinity Y determined by the above formula (1) of 8.94 is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Comparative Example 2 As shown in FIG. 7, among the X-ray diffraction spectra measured using the characteristic X-ray of copper as the radiation source, the Bragg angle (2θ)
7.800 °, 10.480 °, 12.880 °, 1
3.500 °, 15.400 °, 16.660 °, 1
7.360 °, 18.760 °, 22.840 °, 2
It has strong diffraction peaks at 4.520 °, 25.640 ° and 28.900 °, and the diffraction line intensity A of the diffraction peak at the Bragg angle (2θ) of 7.800 °.
Based on the background diffraction line intensity B at the same Bragg angle (2θ) of 7.800 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 7.78 determined by the above formula (1) is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Comparative Example 3 As shown in FIG. 8, the Bragg angle (2θ) in the X-ray diffraction spectrum measured using the characteristic X-ray of copper as the radiation source.
7.860 °, 10.380 °, 12.780 °, 1
3.420 °, 15.380 °, 16.480 °, 1
7.580 °, 18.680 °, 22.720 °, 2
Diffraction line intensity A of the diffraction peak at the Bragg angle (2θ) of 7.860 ° while having strong diffraction peaks at 4.460 °, 25.560 ° and 28.840 °,
Based on the background diffraction line intensity B at the same Bragg angle (2θ) of 7.860 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 4.59 determined by the above formula (1) is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Comparative Example 4 As shown in FIG. 9, the Bragg angle (2θ) in the X-ray diffraction spectrum measured using the characteristic X-ray of copper as the radiation source.
7.780 °, 10.340 °, 12.820 °, 1
3.380 °, 15.380 °, 16.540 °, 1
7.620 °, 18.620 °, 22.740 °, 2
Diffraction line intensity A of the diffraction peak at the Bragg angle (2θ) of 7.780 ° while having strong diffraction peaks at 4.440 °, 25.580 ° and 28.800 °,
From the background diffraction line intensity B at the same Bragg angle (2θ) of 7.780 °, α-type oxotitanyl phthalocyanine having a crystallinity Y of 3.29 obtained by the above formula (1) is used as a charge generating agent. An electrophotographic photosensitive member having a single-layer type photosensitive layer was produced in the same manner as in Example 1 except that it was used.

Electrical Property Test (1) The electrophotographic photosensitive members of the above Examples and Comparative Examples were charged in a dark place by corona discharge so that the surface potential became +700 V ± 20 V.

Then, the above electrophotographic photosensitive member was processed at a wavelength of 780
After exposure with monochromatic light having a wavelength of 10 nm and a light intensity of 10 μW / cm ² for 0.1 second, the surface potential at the time when 1 second has elapsed from the start of the exposure was measured as the residual potential Vr (V).
The results are shown in Table 1.

[0062]

[Table 1]

From Table 1, α having a crystallinity Y of 15 or more
The electrophotographic photoreceptors of Examples 1 to 4 in which the oxo-titanyl phthalocyanine of the α-type was used as the charge generating agent were all compared with each other in which the α-type oxo-titanyl phthalocyanine having the crystallinity Y of less than 15 was used as the charge-generating agent. Examples 1-4
It was found that the residual potential was significantly smaller than that of. From this, it was confirmed that the electrophotographic photoreceptors of Examples 1 to 4 had dramatically improved sensitivity as compared with Comparative Examples 1 to 4.

Examples 5 to 8 and Comparative Examples 5 to 8 As charge generating agents, Examples 1 to 4 and Comparative Examples 1 to 1, respectively.
The same α-type oxotitanyl phthalocyanine as used in 4 was used, and 100 parts by weight of this α-type oxotitanyl phthalocyanine was mixed with 100 parts by weight of polyvinyl butyral which is a binder resin in a ball mill together with butanol. By dispersing, a coating liquid for the charge generation layer was obtained.
Then, this coating solution is applied onto an aluminum substrate, which is a conductive base material, using a wire bar, and is applied at 110 ° C. for 30 minutes.
It was dried with hot air for 1 minute to form a charge generation layer having a film thickness of 0.5 μm.

Further, as the charge transport agent, the above formula (HT1-1)
100 parts by weight of the benzidine compound represented by and 100 parts by weight of polycarbonate as a binder resin were mixed and dispersed with tetrahydrofuran in a ball mill to obtain a coating liquid for the charge transport layer. Then, this coating solution is applied onto the charge generation layer using a wire bar, and dried with hot air at 110 ° C. for 30 minutes to give a film thickness of 20 μm.
The charge transport layer of 1 was formed to produce an electrophotographic photosensitive member having a laminated photosensitive layer. Electrical Characteristic Test (2) The electrophotographic photosensitive members of the above-mentioned Examples and Comparative Examples were charged in a dark place by corona discharge so that the surface potential became −700 V ± 20 V.

Then, the above electrophotographic photosensitive member is processed at a wavelength of 780
After exposure with monochromatic light having a wavelength of 10 nm and a light intensity of 10 μW / cm ² for 0.1 second, the surface potential at the time when 1 second has elapsed from the start of the exposure was measured as the residual potential Vr (V).
Table 2 shows the results.

[0067]

[Table 2]

From Table 2, α having a crystallinity Y of 15 or more
The electrophotographic photoreceptors of Examples 5 to 8 in which the oxo-titanyl phthalocyanine type was used as the charge generating agent were all compared with each other in which the α-type oxo titanyl phthalocyanine having the crystallinity Y of less than 15 was used as the charge generating agent. Examples 5-8
It was found that the residual potential was significantly smaller than that of. From this, it was confirmed that the electrophotographic photoreceptors of Examples 5 to 8 had dramatically improved sensitivity as compared with Comparative Examples 5 to 8.

[0069]

As described above in detail, the electrophotographic photoreceptor of the present invention uses α-type oxotitanyl phthalocyanine having a high degree of crystallinity, which has never been used, as a charge generating agent, and therefore has excellent sensitivity characteristics. It becomes a thing.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for obtaining a crystallinity Y of α-type oxotitanyl phthalocyanine from a characteristic X-ray diffraction spectrum.

FIG. 2 is a graph showing a characteristic X-ray diffraction spectrum of α-type oxotitanyl phthalocyanine used in Examples 1 and 5 of the present invention.

FIG. 3 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Examples 2 and 6 of the present invention.

FIG. 4 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Examples 3 and 7 of the present invention.

FIG. 5 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Examples 4 and 8 of the present invention.

FIG. 6 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Comparative Examples 1 and 5 of the present invention.

FIG. 7 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Comparative Examples 2 and 6 of the present invention.

FIG. 8 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Comparative Examples 3 and 7 of the present invention.

FIG. 9 is a graph showing characteristic X-ray diffraction spectra of α-type oxotitanyl phthalocyanine used in Comparative Examples 4 and 8 of the present invention.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer containing at least a charge generating agent, wherein the charge generating agent is α
Has a crystal type of Of the X-ray diffraction spectrum measured with the Bragg angle (2θ) of 7.6 ± 0.3 ° as the X-ray diffraction spectrum and the common between the valleys on both sides sandwiching this diffraction peak. When connected by a tangent line, from the background diffraction line intensity represented by the intensity B of this tangent line at the same Bragg angle as the above diffraction peak, the formula (1): An electrophotographic photoreceptor containing oxotitanyl phthalocyanine having a crystallinity Y of 15 or more as determined by