JP2615760B2 - Photoconductor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoreceptor having a photosensitive layer containing titanyl phthalocyanine, and more particularly to a photoreceptor having high sensitivity in a long wavelength region.

2. Description of the Related Art In general, in electrophotography, an electrostatic latent image is formed by charging and exposing the surface of a photosensitive layer of a photoreceptor, developing the latent image with a developer, and visualizing the latent image. A direct method in which a copy image is obtained by fixing the image on the surface, a powder image transfer method in which the visible image on the photoconductor is transferred onto a transfer material such as paper, and the transferred image is fixed to obtain a copy image. A latent image transfer method for transferring an electrostatic latent image on a transfer sheet and developing and fixing the electrostatic latent image on the transfer sheet is known.

As a material constituting a photosensitive layer of a photoreceptor used in this type of electrophotography, conventionally, selenium, cadmium sulfide,
Inorganic photoconductive materials such as zinc oxide are known. These photoconductive materials have many advantages, for example, less charge dissipation in a dark place, or the ability to quickly dissipate charge by light irradiation, but have various disadvantages. For example, in the case of a selenium-based photoconductor, manufacturing conditions are difficult, the manufacturing cost is high, and the selenium-based photoconductor is susceptible to heat and mechanical shock.

Cadmium sulfide photoreceptors and zinc oxide photoreceptors do not provide stable sensitivity in humid environments, and dyes added as sensitizers cause charge deterioration due to corona charging and photobleaching due to exposure, resulting in long-term However, there is a disadvantage that stable characteristics cannot be provided over a wide range.

On the other hand, various organic photoconductive materials such as polyvinyl carbazole have been proposed. However, these organic photoconductive materials are different from the above-mentioned inorganic photoconductive materials in terms of film-forming property and lightness. , But still has sufficient sensitivity,
It is inferior to inorganic photoconductive materials in durability and stability due to environmental changes.

In recent years, a stacked photoreceptor that separates the functions of charge generation and transport has been proposed, and the organic photoreceptor has been put to practical use as a result of greatly improving the disadvantages of conventional photoreceptors using organic photoconductive materials. Is making rapid progress.

The laminated photoreceptor has a configuration in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate such as metal aluminum or copper.

These laminated photoreceptors satisfy basic conditions such as charge retention, high sensitivity, repetition stability, dielectric breakdown resistance, abrasion resistance, durability, moisture resistance, transferability, and cleaning storage safety. Is required.

Further, the laminated photoreceptor is also used for a laser printer using a light source having an emission wavelength of around 780 nm, and high image reliability and repetition stability during reversal development have been required.

A phthalocyanine pigment is known as one of the organic photoconductive materials used for the charge generation layer of such a laminated photoreceptor.

However, phthalocyanine-based pigments are inferior in light sensitivity in a long wavelength region, and thus are unsuitable for application to a photoreceptor for a laser printer using, for example, a long-wavelength light near an emission wavelength of 780 nm as a light source. Fog may occur.

A technique for improving the sensitivity characteristics by giving the photosensitivity range of phthalocyanine to a long wavelength range is described in, for example, JP-A-59-166959.

The above technique is a titanyl phthalocyanine film obtained by evaporating titanyl phthalocyanine and then contacting with a vapor of a soluble solvent, and having a specific infrared absorption spectrum and a crystal structure exhibiting an X-ray diffraction spectrum. Is used for the charge generation layer.
It discloses that a photoreceptor having excellent photosensitivity can be obtained even in a long wavelength region of 0 nm or more.

Also, JP-A-62-272272 discloses that, in the X-ray diffraction diagram, 7.6, 10.2, 12.6, 13.2, 15.1, 16.2, 17.2, 18.
3, 22.5, 24.2, 25.3, 28.6, 29.3, α-type titanyl phthalocyanine having an X-ray diffraction peak at 31.5 and 7.4, 9.2, 10.3, 13.0, 14.9, 15.3, 15.9, in the X-ray diffraction diagram
Β-type titanyl phthalocyanines having X-ray diffraction peaks at 18.6, 20.6, 23.2, 25.5, 26.2, 27.0 and 32.7 are disclosed.

JP-A-62-67094 discloses an X-ray diffraction diagram
9.3, 10.6, 13.2, 15.1, 15.7, 16.1, 20.8, 23.3, 26.
3, 27.1 disclose a β-form-like titanyl phthalocyanine having an X-ray diffraction peak.

The titanyl phthalocyanine to be disclosed in the present application has a crystal structure that is completely different from the crystal structure of titanyl phthalocyanine disclosed in the above technology in X-ray diffraction.

The present invention provides a photoreceptor using titanyl phthalocyanine having a novel crystal form.

SUMMARY OF THE INVENTION Since the conventional phthalocyanine pigment has poor light sensitivity in a long wavelength region, the present invention is applied to a photoreceptor for a laser printer using a long wavelength light near an emission wavelength of 780 nm as a light source, for example. However, it is intended to solve the problem of poor sensitivity, poor sensitivity, and image fogging.

Means for Solving the Problems To solve the above problems, the present invention provides a photoconductor having at least a photosensitive layer on a conductive substrate, wherein the photosensitive layer has a Bragg angle (2θ ± 0.2) in X-ray diffraction.
゜) 6.7 ゜, 7.4 ゜, 10.2 ゜, 12.6 ゜, 15.2 ゜, 16.0 ゜,
17.1 ゜, 18.2 ゜, 22.4 ゜, 23.2 ゜, 24.2 ゜, 25.2 ゜, 2
A photoreceptor characterized in that it is a photosensitive layer containing titanyl phthalocyanine having a crystal structure showing an X-ray diffraction peak at 8.5 °.

The titanyl phthalocyanine used in the present invention has the general formula [I] (Wherein X represents a halogen atom or a nitro group, and n represents 0
Shows an integer of ~ 8. ) A compound having a structure represented by

Of the compounds of the general formula [I], unsubstituted and tetrahalogen-substituted compounds are particularly preferred.

The titanyl phthalocyanine used in the present invention is disclosed in
Starting from α-form titanyl phthalocyanine obtained by a known method such as 61-217050 and the like, X
The crystal is converted into a unique crystal structure by X-ray diffraction. Hereinafter, this will be described in detail.

First, the above-mentioned α-type titanyl phthalocyanine is firstly treated into fine powder. At this time, in order to convert the crystal into a crystal structure unique to the present invention, the above-mentioned fine powder is approximately 0.1 μm.
In addition, the fine powder must be in a crystalline amorphous state. This is because this fine powder needs to be converted into crystal nuclei for converting the above-mentioned α-type titanyl phthalocyanine as a starting material into a crystal form of the final product of the present invention.

This primary treatment cannot be treated sufficiently finely as a crystal nucleus to grow into a crystal form of the final product of the present invention by using a ball mill, a sand mill, an eye lighter, etc. among known milling devices, LIMMAC (Linear Induction M
otor Mixing and Crashing (manufactured by Fuji Electric Co., Ltd.) can be sufficiently finely ground, and the fine powder obtained at this time is in an amorphous state, and the crystal nuclei of the final product of the present invention are obtained. Has been confirmed by the present inventor.

Further, in order to make the micropowder have a crystal structure unique to the present invention, a secondary treatment for growing crystals in a chlorinated aliphatic hydrocarbon solvent is required.

The titanyl phthalocyanine of the present invention obtained through the primary treatment and the secondary treatment was measured by an X-ray diffraction method,
FIG. 1 is an X-ray diffraction spectrum diagram. FIG. 1 shows the measurement results in the Bragg angle range of 5 ° to 40 ° by the above method.

Regarding other substituents such as halogen atoms used in the present invention, the above-mentioned specific peaks are common in their X-ray diffraction diagrams irrespective of the substitution position or the substitution number.

The titanyl phthalocyanine of the present invention has an ionization potential of 5.0 to 5.4 eV, and the ionization potential can be measured using a known means, for example, a surface analyzer (AC: 1; manufactured by Riken Keiki Co., Ltd.).

FIGS. 2 to 4 show X-ray diffraction spectra of titanyl phthalocyanines other than the present invention. FIG. 2 reflects the crystal structure of α-form titanyl phthalocyanine, FIG. 3 reflects the crystal structure of β-form titanyl phthalocyanine, and FIG. 4 reflects the crystal structure of similar β-form titanyl phthalocyanine. It turns out that they are clearly different.

5 to 9 schematically show examples of the constitution of a photoreceptor using titanyl phthalocyanine of the present invention.

FIG. 5 shows a charge generation material (3) on a conductive substrate (1).
And a charge transport material (2) mixed with a binder resin.
An example of the configuration of a photoreceptor using the titanyl phthalocyanine of the present invention is shown below.

FIG. 6 shows a laminated photoreceptor having a charge generating layer (6) as a photosensitive layer and a charge transporting layer (5). The charge transporting layer (5) is formed on the surface of the charge generating layer (6). 2 shows a configuration example of a photoconductor.

In the charge generation layer (6), the titanyl phthalocyanine of the present invention is blended with a binder resin.

FIG. 7 shows a laminated photoreceptor having a charge generation layer (6) and a charge transport layer (5) as in FIG. 2, but the surface of the charge transport layer (5) is opposite to FIG. 2 shows a configuration example of a photoreceptor having a charge generation layer (6) formed thereon.

FIG. 8 shows that the surface protective layer (7) is further provided on the surface of the photoreceptor of FIG. 1, and the photosensitive layer (4) has a charge generation layer (6) and a charge transport layer (5). An example of the configuration of a laminated photoconductor is shown.

FIG. 9 shows that an intermediate layer (8) is provided between the conductive substrate (1) and the photosensitive layer (4). The intermediate layer (8) has improved adhesiveness, improved coating properties, and improved substrate. An example of the structure of a photoreceptor provided for protecting the photoconductor and improving the charge injection property from the substrate to the photosensitive layer is shown below.

The photoreceptor of the present invention has a photosensitive layer containing one or more kinds of titanyl phthalocyanines represented by the above general formula.

Although various types of photoconductors are known, the photoconductor of the present invention may be any of those photoconductors.

For example, a single-layer type photoreceptor having a photosensitive layer formed by dispersing titanyl phthalocyanine in a binder resin or a charge transport medium on a support, or a charge generation layer containing titanyl phthalocyanine as a main component on a conductive substrate. There is a so-called stacked type photoconductor in which a charge transport layer is provided thereon. The titanyl phthalocyanine of the present invention acts as a charge generating substance, generates charge carriers with extremely high efficiency when absorbing light, and the generated charge carriers can be mailed using titanyl phthalocyanine as a medium. The transported method is even more effective.

In order to produce a single-layer photoreceptor, fine particles of titanyl phthalocyanine may be dispersed in a resin solution or a solution in which a charge transport substance and a resin are dissolved, and the dispersion may be applied on a conductive support and dried. The thickness of the photosensitive layer at this time is 3 to
The thickness is 30 μm, preferably 5 to 20 μm.

If the amount of titanyl phthalocyanine used is too small, the sensitivity is poor, and if it is too large, the chargeability is poor and the mechanical strength of the photosensitive layer is low. The ratio of titanyl phthalocyanine in the photosensitive layer was 0.1 part by weight based on 1 part by weight of the resin.
The range is from 01 to 3 parts by weight, preferably from 0.2 to 2 parts by weight. Further, in the case of a charge transporting substance such as polyvinyl carbazole, which can be used as a binder resin by itself, the amount of titanyl phthalocyanine added is 1
It is preferable to use 0.01 to 0.5 parts by weight based on parts by weight.

To prepare a laminated photoreceptor, after coating and drying a coating solution prepared by dispersing titanyl phthalocyanine in a suitable solvent or a solution in which a binder resin is dissolved if necessary on a conductive support, A solution containing a charge transport material and a binder resin is applied thereon and dried. At this time, the thickness of the titanyl phthalocyanine layer serving as the charge generation layer was 4 μm.
m or less, preferably 2 μm or less, and the thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 50 μm. The ratio of the charge transporting substance in the charge transporting layer is 0.2 to 2 parts by weight, preferably 0.3 to 1.3 parts by weight based on 1 part by weight of the binder resin.
In the case of a charge transport material that can be used as a binder by itself, other binders may not be used.

The photoreceptor of the present invention, together with a binder resin, halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutylphthalate, a plasticizer such as 0-terphenyl, chloranil, tetracyanoethylene, 2,4,7-trinitrofluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-
Electron-withdrawing sensitizers such as dinitrobenzoic acid, methyl violet, rhodamine B, cyanine dye, pyrylium salt,
A sensitizer such as a thiapyrylium salt may be used. As the electrically insulating binder resin used in the present invention, a binder resin such as a thermoplastic resin or a thermosetting resin, a photocurable resin, a photoconductive resin, or the like, which is electrically insulating, is used. it can. Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate resins, ionically crosslinked olefin copolymers (ionomers), and styrene-butadiene block copolymers. Polymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester,
Thermoplastic resins such as polyimide and styrene resin; epoxy resins, urethane resins, silicone resins, phenol resins, melamine resins, xylene resins, alkyd resins, thermosetting resins such as thermosetting acrylic resins; photo-curing resins; polyvinyl carbazole; Photoconductive resins such as polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole. These can be used alone or in combination. These electrically insulating resins were measured alone to give 1 × 10
It is desirable to have a volume resistance of ¹² Ω · cm or more.

As the charge transport material, hydrazone compounds, pyrazoline compounds, styryl compounds, triphenylmethane compounds, oxadiazole compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, triphenylamine compounds, tetphenylbenzidine compounds, azine compounds, etc. Although various things can be used, for example, carbazole, N-ethylcarbazole, N-vinylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2,3-benzochrysene, 3,4-benzopyrene, fluorene, 1.2-benzofluorene, 4- (2-fluorenylazo) resorcinol, 2-p-anisoleaminofluorene, p-diethylaminoazobenzene, cadion N, N-dimethyl -p
-Phenylazoaniline, p- (cimethylamino) stilbene, 1,4-bis (2-methylstyryl) benzene,
9- (4-diethylaminostyryl) anthracene, 2,
5-bis (4-diethylaminophenyl) -1,3,5-oxadiazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrrarizone, 1-phenyl-3-phenyl -5-pyrazolone, 2- (m-naphthyl) -3-phenyloxazole, 2- (p-diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminomistyryl) -6-diethylaminobenzothiazole,
Bis (4-diethylamino-2-methylphenyl) phenylmethane, 1,1-bis (4-N, N-diethylanomy-2)
-Ethylphenyl) heptane, N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, N,
N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, 1,1,2,2, tetrakis- (4-N, N-
Diethylamino-2-ethylphenyl) ethane, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N, N
-Diphenylhydrazone, N-ethylcarbazole-N
-Methyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-3
-Methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N, N-diphenylanomi-β-phenylstilbene, α-phenyl-4-N, N-diphenylanomistilbene and the like. A styryl compound represented by the following general formula [II]; [In the formula, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ represent an aryl group which may have a substituent. n represents 0 or 1. Or a hydrazone compound represented by the following general formula [III]; Wherein X and Y are each independently hydrogen, a lower alkyl group, a methoxy group, or an ethoxy group, Z is a lower alkyl group, a benzyl group, a lower alkoxy group, a phenoxy group or a benzyloxy group, and Z ′ is a hydrogen atom. , An alkyl group or an alkoxy group, and R represents a lower alkyl group, an aryl group which may have a substituent, or a benzyl group. ] Etc. can be mentioned. These charge transport materials are used alone or in combination of two or more.

Among the above charge transport materials, styryl compounds represented by the general formula [I] and hydrazone compounds represented by the general formula [II] are preferable, and styryl compounds represented by the general formula [I] are particularly preferable.

Specific examples of the styryl compound represented by the general formula [II] include the following compounds; And [3], [4], [5], [7],
[8], [9], [11], [12], [13], [14],
Compounds represented by [15] and [18] are preferred.

Specific examples of the hydrazone compound represented by the general formula [III] include the following compounds; And [23], [24], [25], [29],
Compounds represented by [32] and [33] are preferred.

However, it is not limited to these compounds.

These charge transport materials are used alone or in combination of two or more.

In addition, any of the photoconductors obtained as described above may be provided with an intermediate layer such as an adhesive layer or a barrier layer, and a surface protective layer, if necessary.

As a material used for the intermediate layer, polyimide, polyamide, nitrocellulose, polyvinyl butyral, a polymer such as polyvinyl alcohol as it is, or a dispersion of a low-resistance compound such as tin oxide or indium oxide, aluminum oxide, zinc oxide, A deposited film of silicon oxide or the like is suitable.

 The thickness of the intermediate layer is desirably 1 μm or less.

Acrylic resin,
Suitable are polymers such as polyaryl resins, polycarbonate resins and urethane resins as they are, or dispersions of low-resistance compounds such as tin oxide and indium oxide, and vapor-deposited films of aluminum oxide, zinc oxide and silicon oxide.

Also, an organic plasma polymerized film can be used. The organic plasma polymerized film may contain oxygen, nitrogen, halogen, and atoms of Groups 3 and 5 of the Periodic Table as needed.

The thickness of the surface protective layer is desirably 5 μm or less. As the conductive support used in the photoreceptor of the present invention, copper,
Aluminum, silver, iron, zinc, nickel or other metal or alloy foils or plates in the form of sheets or drums are used, or these metals are vacuum-deposited or electroless-plated on plastic films, etc. Alternatively, a layer obtained by applying or depositing a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide on a support such as paper or a plastic film is also used.

Preparation 1. 10.2 parts of 0-phthalodinitrile and 3.8 parts of titanium tetrachloride were suspended in 50 ml of α-chloronaphthalene, heated to 210 ° C. to 215 ° C., and reacted for 3 hours. The reaction mixture was cooled, and the crystals were collected by filtration and washed with acetone and methanol. After drying, the dark blue solid was slurried twice in refluxing dimethylformamide, filtered hot, and washed with acetone.

5 parts of the obtained titanyl phthalocyanine was dissolved in 50 ml of concentrated sulfuric acid with cooling, and this solution was added to 500 ml of ice water with stirring.

The precipitated blue crystals were washed with water until the acid disappeared, and collected by filtration.

The obtained titanyl phthalocyanine was subjected to fine powder treatment with a pulverizer (LIMMAC (manufactured by Fuji Electric)) together with Teflon beads, and 1 part of this finely powdered sample and 20 parts of dichloroethane were slurried in refluxing dichloroethane, It was filtered while hot and dried to obtain the target sample.

The X-ray diffraction pattern of the sample treated in this manner is shown in FIG.
FIG.

Preparation 2. The sample subjected to the fine powder treatment was subjected to an ultrasonic dispersion treatment with an ultrasonic homogenizer together with 1,1,2 trichloroethane for 1 hour.

Thereafter, the sample and the solvent were separated, filtered, and dried to obtain a target sample.

The titanyl phthalocyanine of the present invention is particularly good as a material for a charge generation layer of a function-separated type photoreceptor, and the photoreceptor of the present invention has excellent long-wavelength sensitivity, and is applicable to laser beam printers, LED printers, liquid crystal printers and the like. Useful for

Hereinafter, the present invention will be described with reference to examples. In the examples, “parts” means “parts by weight” unless otherwise specified.

Example 1 An alumite-treated aluminum drum having an outer diameter of 80 mm and a length of 350 mm is used as a support.

The charge generating material titanyl phthalocyanine of the present invention (production
1.) using 0.45 part of this titanyl phthalocyanine and polyvinyl butyral resin (acetylation degree 3 mol% or less,
Using a sand grinder together with 100 parts of cyclohexanone was dispersed 0.45 parts of a butylation degree of 68 mol% and a polymerization degree of 1500), and 0.3 g of this dispersion was placed on the aluminum drum.
/ m ² to form a charge generation layer.

Next, 70 parts of a styryl compound represented by the formula [4] and 70 parts of a polycarbonate resin K-1300 (manufactured by Teijin Chemicals Limited) were mixed on the charge generation layer in a ratio of 7: 3 of dioxane and cyclohexanone. A coating solution dissolved in a mixed solvent was applied by dip coating and dried to form a charge transport layer having a thickness of 18 μm.

Thus, a function-separated type photoconductor in which the charge generation layer and the charge transport layer were laminated on the aluminum drum was obtained.

Examples 2 to 6 Photoconductors were prepared in the same manner as in Example 1 except that the CT material used for the charge transport layer was changed to Formulas (5), (7), (12) and (28) (20). Was prepared.

COMPARATIVE EXAMPLE 1. X shown in FIG.
A photoreceptor was prepared in the same manner as in Example 1 using α-type titanyl phthalocyanine having a line diffraction peak.

Comparative Example 2. A photoconductor was prepared in the same manner as in Example 1, except that β-type titanyl phthalocyanine having an X-ray diffraction peak shown in FIG. 3 was used as the charge generating material in Example 1.

Comparative Example 3. A photoconductor was prepared in the same manner as in Example 1, except that a similar β-type titanyl phthalocyanine having an X-ray diffraction peak shown in FIG.

The obtained photoreceptor is used as a light source laser optical system (780 nm wavelength).
m) was replaced with an electrophotographic copying machine (EP-570Z: manufactured by Minolta Camera Co., Ltd.) and charged with a corona at −6 KV to halve the initial surface potential Vo (V) and the initial potential (Vo). The amount of exposure required for this (half exposure, E1 / 2 (erg / cm ² )) was measured for the decay rate DDR (%) of the initial potential when left in the dark for 1 second. The results are shown in Table 1.

Effects of the Invention As described above, according to the photoreceptor of the present invention, charge retention, high sensitivity, and repetition stability required for the photoreceptor are generally required in electrophotography, regardless of whether the photoreceptor is a single-layer type or a laminated type. sex,
It has basic characteristics such as dielectric breakdown resistance, abrasion resistance, durability, moisture resistance, transferability, cleaning properties, storage stability, and 78
Even when used as a photoreceptor such as a laser printer using a long-wavelength laser light of 0 nm, the photoreceptor has good sensitivity and has an effect that image fogging does not occur.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction spectrum of titanyl phthalocyanine of the present invention. 2 to 4 are X-ray diffraction spectrum diagrams of titanyl phthalocyanine other than the present invention. FIG. 5 to FIG. 9 are schematic diagrams showing examples of the constitution of a photoreceptor using titanyl phthalocyanine of the present invention. DESCRIPTION OF SYMBOLS 1 ... Conductive board | substrate, 2 ... Charge transport material 3 ... Charge generation material 4, ... Photosensitive layer 5 ... Charge transport layer, 6 ... Charge generation layer

Claims (1)

(57) [Claims] 1. A photosensitive member having at least a photosensitive layer on a conductive substrate, wherein the photosensitive layer is formed by X-ray diffraction.
Bragg angle (2θ ± 0.2 ゜) X at positions of 6.7 ゜, 7.4 ゜, 10.2 ゜, 12.6 ゜, 15.2 ゜, 16.0 ゜, 17.1 ゜, 18.2 ゜, 22.4 ゜, 23.2 ゜, 24.2 ゜, 25.2 ゜, 28.5 にA photoreceptor comprising a photosensitive layer containing titanyl phthalocyanine having a crystal structure showing a line diffraction peak.