JP3033585B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor having high sensitivity and excellent characteristics from a visible light region to a near infrared wavelength region.

[Conventional technology and its problems]

2. Description of the Related Art Conventionally, photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used for a photosensitive layer of an electrophotographic photosensitive member.

Researches using organic photoconductive substances represented by polyvinyl carbazole for the photosensitive layer of an electrophotographic photoreceptor have been advanced, and some of them have been put to practical use.

An organic photoconductive substance can be easily formed into a light-weight film as compared with an inorganic material. It is easy to manufacture the photoreceptor.
The material has advantages such as harmlessness.

In recent years, laser beam printers (LBPs), which use laser light as a light source instead of conventional white light and have advantages of high speed, high image quality, and non-impact, have become widespread in conjunction with the progress of information processing systems. There is a demand for the development of materials that can withstand such demands.

In particular, among laser beams, in recent years, applications to compact discs, optical discs, and the like have increased, and semiconductor lasers, which have undergone remarkable technological progress, have been actively applied in the field of printers as compact and highly reliable light source materials.

In this case, since the wavelength of the light source is around 800 nm, 800 nm
There is a strong demand for the development of a photoreceptor having high sensitivity to long wavelength light before and after.

JP-A-59-49544, 5
9-214034, 60-109056, 61-177171, 61-21705
No. 0, 61-239248, 62-67094, 62-133461, 62-
275272, 63-198067, 63-198068, 63-210942
And 63-218768, and various oxytitanium phthalocyanines each having a suitable crystal type as a material for an electrophotographic photosensitive member are known. However, there has been a demand for an electrophotographic photoreceptor that has higher sensitivity to long-wavelength light and good other electrical characteristics.

The present inventors have conducted intensive studies on an electrophotographic photoreceptor using oxytitanium phthalocyanines and found that the X-ray diffraction spectrum showed a Bragg (2θ ± 0.2 °) of 27.3.
When a photoreceptor is prepared using oxytitanium phthalocyanine, which exhibits a main folding peak as a charge transport material, and a specific compound as a charge transport material, the desired purpose is achieved, and the chargeability, sensitivity, dark decay, and residual potential are achieved. The present inventors have found that it is possible to provide a well-balanced electrophotographic photoreceptor, and have completed the present invention.

[Means for solving the problem]

That is, the gist of the present invention is to provide a photoconductor for electrophotography having a photosensitive layer containing a charge generating material and a charge transporting material on a conductive support, and as a charge generating material, a Bragg angle (X-ray diffraction spectrum) 2θ ± 0.2 °) Oxytitanium phthalocyanine showing a main diffraction peak at 27.3 ° is used, and the following general formula [I] is used as a charge transporting material.
Or [II] (In the formula, R ¹ and R ² are a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, an aralkyl group, an allyl group, an aryl group or a halogen atom such good .R ³ and be different from each other in the same R ⁴ represents an alkyl group, an aralkyl group, an allyl group or an aryl group, which may be the same or different from each other, and n represents a number of 0 or 1.
X represents a direct bond forming a ring, a methylene residue or an ethylene residue, -O- Or -S-. R ⁵ represents a hydrogen atom, an alkyl group, an aralkyl group, an allyl group, or an aryl group.

However, in the general formula [I], the case where n represents 0, R ³ represents an alkyl group or an aryl group, and R ⁴ represents an alkyl group or an aryl group is excluded. ) Wherein the compound represented by the formula (1) is used.

(Operation) Hereinafter, the present invention will be described in detail.

Of the materials for forming the electrophotographic photoreceptor of the present invention, oxytitanium phthalocyanine used as a charge generating material has a main diffraction peak at 27.3 ° at a Bragg angle (2θ ± 0.2 °) in its X-ray diffraction spectrum. In the present invention, “main diffraction peak” refers to the X
It refers to the strongest (highest) peak in the line diffraction spectrum.

Oxytitanium phthalocyanine powder X used
Examples of the line spectrum are shown in FIGS. As shown
The main peak is the diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 °. Other than the peak, various peaks occur depending on detailed conditions. ) Is preferably 50% or less as an electrophotographic photoreceptor in terms of chargeability, sensitivity and the like.

The method for producing oxytitanium phthalocyanine used in the present invention is not particularly limited, but is produced, for example, by the following method.

A method for producing type [II] crystals described in Production Example 1 of JP-A-62-67094. That is, orthophthalodinitrile and a halide of titanium are heated and reacted in an inert organic solvent, and then hydrolyzed.

Direct Various crystal forms of oxytitanium phthalocyanine, an organic acid solvent, sulfuric acid or the formula R-SO ₃ H (represented in the formula, R may have a substituent, an aliphatic or aromatic residue.) Heat treatment with a sulfonated compound represented by
In some cases, the mixture is then heated with a mixed solvent of a water-insoluble organic solvent and water.

If desired, after previously dissolving in concentrated sulfuric acid and releasing it into ice water, or making it amorphous by a known method such as a mechanical grinding method such as a paint shaker, ball mill, side grind mill, etc., heat-treat with the above sulfonated product or water. Heat treatment is performed with a mixed solvent of an insoluble organic solvent and water.

In the case of the above-mentioned treatment with a sulfonated product, it can also be produced by using a mechanical grinding method such as a paint shaker, a ball mill, or a sand grinding mill instead of the heat treatment.

As the charge transporting material, a compound represented by the general formula [I] or [II] is used.

In the general formulas [I] and [II], R ¹ and R ² are hydrogen atoms; mainly lower alkyl groups such as methyl group and ethyl group; mainly lower alkoxy groups such as methoxy group and ethoxy group; dimethylamino group A substituted amino group such as diethylamino group and morpholino group; an aralkyl group such as benzyl group and phenethyl group; an allyl group; an aryl group such as phenyl group and naphthyl group or a halogen atom such as chlorine atom and bromine atom, which are the same. However, they may be different from each other. Preferred are a hydrogen atom, a methyl group, a methoxy group, a dimethylamino group and the like.

R ³ and R ⁴ are mainly lower alkyl groups such as methyl group, ethyl group and butyl group; aralkyl groups such as benzyl group and phenethyl group; allyl group; phenyl group;
It represents a substituted phenyl group such as a methoxyphenyl group, a chlorophenyl group, a biphenyl group, or an aryl group such as a naphthyl group, which may be the same or different.
Among them, a phenyl group is preferred. N represents a number of 0 or 1. However, in the general formula [I], the case where n represents 0, R ³ represents an alkyl group or an aryl group, and R ⁴ represents an alkyl group or an aryl group is excluded. In the general formula [II], X represents a direct bond forming a ring, a methylene residue or an ethylene residue —O—, Or -S-. Here, R ⁵ represents a hydrogen atom, mainly a lower alkyl group such as a methyl group or an ethyl group; an aralkyl group such as a benzyl group or a phenethyl group; an aryl group such as an allyl group or a phenyl group or a naphthyl group. Among them, X is particularly preferably a direct bond forming a ring or Among them, R ⁵ is a methyl group, an ethyl group, etc. It is.

The photosensitive member of the present invention will be described in more detail. The photosensitive member of the present invention contains a charge generating material and a charge transport material in a photosensitive layer formed on a conductive support. Specifically, the photoreceptor of the present invention usually forms a charge generation layer by directly depositing a charge generation material or applying it as a dispersion with a binder, forming a charge generation layer thereon, and dissolving the cast or binder from an organic solvent solution. The photoreceptor is a laminate type photoreceptor in which a charge transport layer containing a charge transport material is formed by coating with a dispersion, but the order of lamination of the charge generation layer and the charge transport layer may be reversed.

Further, the photoreceptor of the present invention may be a single-layer type photoreceptor obtained by applying a coating solution in which a charge generating material and a charge transporting material are dispersed and dissolved in a binder on an electrically conductive support.

In addition, a layer for improving electrical and mechanical properties, such as an intermediate layer such as an adhesive layer and a blocking layer, and a protective layer may be provided.

As the conductive support, any of those used in known electrophotographic photoreceptors can be used. Specific examples include metal drums and sheets of aluminum, stainless steel, copper and the like, and laminates and vapor-deposits of these metal foils. Further, a plastic film, a plastic drum, paper, a paper tube, and the like, which are subjected to a conductive treatment by applying a conductive substance such as metal powder, carbon black, copper iodide, and a polymer electrolyte together with an appropriate binder, may be mentioned. Further, a plastic sheet or drum containing a conductive substance such as a metal powder, carbon black, or carbon fiber to become conductive may be used.

Further, plastic films and belts which have been subjected to conductive treatment with a conductive metal oxide such as tin oxide or indium oxide may be used. The charge generation layer formed on these conductive supports is formed by dissolving or dispersing the oxytitanium phthalocyanine particles of the present invention and the binder polymer and, if necessary, the organic photoconductive compound, the dye, and the electron-withdrawing compound in a solvent. The obtained coating liquid is obtained by coating and drying. As the binder, styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinyl alcohol, polymers and copolymers of vinyl compounds such as vinyl such as ethyl vinyl ether, polyvinyl acetal,
Examples include polycarbonate, polyester, polyamide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, epoxy resin and the like. The ratio of oxytitanium phthalocyanine to binder polymer is not particularly limited, but generally, 5 to 500 parts by weight, preferably 20 to 300 parts by weight, of binder polymer is used per 100 parts by weight of oxytitanium phthalocyanine.

The thickness of the charge generation layer is 0.05 to 5 μm, preferably 0.1 to 5 μm.
２2 μm.

The charge transport layer into which charge carriers are injected from the charge generation layer contains a charge transport material having high carrier injection efficiency and transfer efficiency.

A binder polymer is used for the charge transport layer as needed. As the binder polymer, a polymer that has good compatibility with the above-described charge transporting material, and does not crystallize or charge-separate the charge transporting material after forming the coating film, is preferable.
Examples thereof include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylates, methacrylates, butadiene, polyvinyl acetal, polycarbonate, polyester,
Examples thereof include polysulfone, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, and epoxy resin.
The amount of binder polymer used is usually 100
It is in the range of 50-3000 parts by weight, preferably 70-1000 parts by weight, based on parts by weight. In addition to the above, various additives for improving the mechanical strength and durability of the coating film can be used in the charge transport layer.

Examples of such additives include well-known plasticizers, various stabilizers, fluidity-imparting agents, and cross-linking agents.

〔The invention's effect〕

The electrophotographic photoreceptor of the present invention obtained in this manner has high sensitivity, low residual potential, high chargeability, and small fluctuation due to repetition, and particularly, good charge stability which affects image density. Therefore, it can be used as a highly durable photoconductor. Also, since the sensitivity is high in the range of 750 to 850 nm, it is particularly suitable for a photosensitive member for a semiconductor laser printer.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Production Examples and Examples. However, the present invention is not limited to the following Production Examples and Examples as long as the gist is not exceeded.

Production Example 1 97.5 g of phthalodinitrile was added to 750 ml of α-chloronaphthalene
Then, under a nitrogen atmosphere, 22 ml of titanium tetrachloride was added dropwise. After the dropwise addition, the temperature was raised, and the mixture was reacted at 200 to 220 ° C. for 3 hours with stirring, then allowed to cool, and heated at 100 to 130 ° C.
Washed with 200 ml of α-chloronaphthalene heated to ℃.
The obtained crude cake was washed with 300 ml of α-chloronaphthale and then with 300 ml of methanol at room temperature, and further washed with 800 ml of methanol for 1 hour while hot, and the obtained cake was placed in 700 ml of water. The resultant was suspended and subjected to hot suspension washing for 2 hours.

The pH of the solution was 1 or less. PH of the solution is 6
Repeated until ~ 7.

FIG. 1 shows an X-ray diffraction spectrum of the obtained oxytitanium phthalocyanine.

As is clear from FIG. 1, the spectrum shows a sharp peak at a Bragg angle (2θ ± 0.2 °) of 27.3 °, but the other peaks are relatively broad peaks.

Production Example 2 40 g of β-type oxytitanium phthalocyanine having the X-ray diffraction spectrum shown in FIG. 3 was dissolved in 400 ml of 98% concentrated sulfuric acid, and the mixture was stirred in an ice bath for 3 hours.

Then, a concentrated sulfuric acid solution was dropped into 1.6 parts of ice water over 30 minutes to make the mixture sufficiently uniform, and then passed. The resulting precipitate is neutralized by suspending and washing with an aqueous solution of sodium acetate and then neutralized by suspending and washing with water.
110 g were obtained.

Further, 85 g of the obtained wet cake was suspended in 770 ml of water, 57 ml of ortho-dichlorobenzene was added, and the mixture was stirred at a temperature of 60 ° C. for 1 hour. The reaction solution was decanted to remove most of the water-ortho-dichlorobenzene, and then 800 ml of methanol was added, and the mixture was stirred at a temperature of 60 ° C. for 2 hours, and then filtered and dried by a conventional method to obtain 18 g of blue oxytitanium phthalocyanine. Obtained.

The second X-ray diffraction spectrum of the obtained oxytitanium phthalocyanine is shown.

The peak in the X-ray diffraction spectrum of oxytitanium phthalocyanine obtained as evident from FIG.
1 has a sharp peak at 27.3 ° at a Bragg angle (2θ ± 0.2 °), but the other peaks are relatively broad peaks.

Example 1 Oxytitanium phthalocyanine produced in Production Example 1
0.4 g of polyvinyl butyral 0.2 g of 4-methoxy-4-
Disperse with a sand grinder together with 30 g of methyl-2-pentanone, apply this dispersion on an aluminum vapor-deposited layer vapor-deposited on a polyester film using a film applicator to a dry film thickness of 0.3 g / m ² and dry. Thus, a charge generation layer was formed.

A film 17 comprising 90 parts of a compound represented by the following chemical formula [III] and 100 parts of a polycarbonate resin (manufactured by Mitsubishi Gas Chemical Company, trade name Iupilon E-2000) is formed on the charge generation layer.
A μm charge transport layer was laminated to obtain an electrophotographic photosensitive member having a laminated photosensitive layer.

The half-life exposure (E1 / 2) was measured as the sensitivity of this photoreceptor using an electrostatic copying paper tester (Model SP-428, manufactured by Kawaguchi Electric Works). That is, the photoconductor is negatively charged by corona discharge with an applied voltage set so that the corona current becomes 50 μA in a dark place, and then 775 nm having an intensity of 0.125 μW / cm ^2.
The exposure amount (E1 / 2) required for halving the surface potential from -500 V to -250 V was calculated to be 0.18
μJ / cm ² .

Example 2 The procedure of Example 1 was repeated except that the compound [III] used in Example 1 was replaced with a compound shown in the following table.

 The results are summarized in the table below.

[Brief description of the drawings]

1 and 2 are X-ray diffraction spectra of oxytitanium phthalocyanine used in the present invention. FIG.
6 is an X-ray diffraction spectrum of β-type oxytitanium phthalocyanine used in Production Example 2.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Junko Watanabe 1000 Kamoshita-cho, Midori-ku, Yokohama-shi, Kanagawa Prefecture, Mitsubishi Chemical Research Institute (56) References JP-A-64-82042 (JP, A) JP-A Sho 63-210942 (JP, A) JP-A-63-316868 (JP, A) JP-A-63-235945 (JP, A)

Claims (1)

(57) [Claims] 1. A photoconductor having a photosensitive layer containing a charge generation material and a charge transport material on a conductive support, the charge generation material having a Bragg angle (2θ ± 0.2 °) 27.3 ° in an X-ray diffraction spectrum. Oxytitanium phthalocyanine showing a main diffraction peak is used, and the following general formula [I] and / or [II] is used as a charge transporting material. (In the formula, R ¹ and R ² are a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, an aralkyl group, an allyl group, an aryl group or a halogen atom such good .R ³ and be different from each other in the same R ⁴ represents an alkyl group, an aralkyl group, an allyl group or an aryl group, which may be the same or different from each other, and n represents a number of 0 or 1. X represents a direct bond forming a ring, Methylene residue or ethylene residue, Or -S-. R ⁵ is a hydrogen atom, an alkyl group,
Represents an aralkyl group, an allyl group or an aryl group. However, in the general formula [I], the case where n represents 0, R ³ represents an alkyl group or an aryl group, and R ⁴ represents an alkyl group or an aryl group is excluded. A photoreceptor for electrophotography, comprising using a compound represented by the formula: