JPH0756372A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain a photoreceptor for a printer and digital having high sensitivity and hardly deteriorating its performance at the time of repeated use by coating specified titanyl phthalocyanine with a polymer insoluble in a medium for dispersing the pigment. CONSTITUTION:Titanyl phthalocyanine pigment crystals whose Bragg angle 2theta in X-ray diffraction with characteristics of CuKalpha has the max. peak at 27.2+ or -0.2 deg. are coated with a polymer insoluble in a solvent for dispersing the pigment so as to ensure stability over a long period of time for a prepd. dispersion liq. Tetrahydrofuran, cyclohexanone, methyl ethyl ketone or dichloroethane may be used as the solvent. The phthalocyanine can be prevented from undergoing a crystal change due to the solvent by making the pigment hydrophobic by surface treatment with a surface treating agent preferably having the structure of metal alkoxide such as an aluminum coupling agent, a titanium coupling agent or a silane coupling agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor. In particular, the present invention relates to a high-sensitivity photoconductor sensitive to a semiconductor laser.

[0002]

2. Description of the Related Art In the past, electrophotography has passed half a century since the principle of electrophotography was announced, and semiconductor lasers have been used to cope with the digital processing from the early photoconductors corresponding to white light to the recent development of electronic devices. We are moving to photoconductors that can handle light.

A semiconductor laser has an oscillation wavelength of 780 to 820.
Since it is in the near-infrared region of nm, it is unsuitable for conventional inorganic photosensitive materials such as Se, and many organic photosensitive materials, particularly photoreceptors using phthalocyanines have been proposed. However, none of them are sufficiently satisfactory, and there are problems such as deterioration of performance during repeated use. There is also a demand for a photoreceptor having higher sensitivity and higher durability.

Considering a positively charged photoreceptor which has attracted much attention in recent years as a more preferable photoreceptor, since the layer containing the pigment is on or near the surface, the pigment is directly affected by the effect and the performance in repeated use is improved. The problem of deterioration of the surface potential, especially the decrease of the surface potential is great.

In the photoconductor, the pigment is wrapped in a binder or has a polymer layer as an upper layer, but these polymers mainly have film physical properties as a photoconductor, electrical properties, or various additives. It is chosen for its solubility chemistry and not necessarily for the purpose of protecting the pigment from the external environment.

Further, when the material side is seen from the side of producing the photoconductor, the phthalocyanines used in the above-mentioned photoconductor have many crystal polymorphisms, and during production, the phthalocyanines are always crystallized when the dispersion is used for a long period of time. There is a fear of conversion. This is a problem that leads to cost increase in dip coating, which is currently the mainstream.

Titanyl phthalocyanines having an X-ray diffraction peak at 27.2 degrees, which is known as a particularly sensitive material (JP-A-64-17066, JP-A-2-309362, JP-A-3-35245,
Although disclosed in JP-A-3-255456 and the like) have high sensitivity, they are all metastable crystals and have no problem in the completed photoconductor, but have a drawback that they are easily subjected to crystal conversion in the dispersion liquid.

Particularly, in the above-mentioned positively charged photoreceptor, the layer containing the pigment is the upper layer, and the binder of the pigment dispersion layer is related to the mechanical strength (film properties) of the photoreceptor. In such photoreceptors, the range of binder selection is limited, and as a result,
In the production, the choice of the dispersion solvent tends to be limited, and it is not allowed to use only the solvent in which the crystal conversion is hard to occur. It is desired to provide a stable dispersion liquid for a cheaper manufacturing method.

[0009] Further, although these are excellent in sensitivity, there is a problem that the sensitivity fluctuates depending on humidity, although it is slight. It is desired to develop a photoconductor that is more environmentally independent. Considering positive charge, which has been attracting attention in recent years as a particularly preferable photoconductor that generates a small amount of ozone, since the layer containing the pigment is on or near the surface, the pigment is directly affected by the change in performance, especially under high temperature and high humidity. It greatly affects the decrease of the surface potential.

[0010]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a printer and a digital photoconductor which have high sensitivity and little deterioration in performance during repeated use. In particular, it is to provide a photoconductor in which the performance is less deteriorated during repeated use under the positive charging specification. A second object of the present invention is to provide a stable dispersion liquid for inexpensively producing the above-mentioned photoreceptor. In the past, vapor deposition and the like were often used for the preparation of the photoconductor, but since special equipment is required in recent years, dipping coating is often used in which the pigment is dispersed and the photoconductor drum is dipped in the liquid. In such a case, a pigment that can have many crystal forms such as phthalocyanines is likely to undergo crystal conversion depending on the solvent.

[0011]

The object of the present invention is CuKα.
The diffraction peak of Bragg angle 2θ in characteristic X-ray diffraction is 2
It was achieved by coating certain titanyl phthalocyanines with a maximum peak at 7.2 ± 0.2 degrees with a polymer insoluble in the dispersion medium. The object of the present invention was also achieved by surface-treating specific titanyl phthalocyanines to make them hydrophobic.

The specific titanyl phthalocyanine crystal is characterized by having a particle size of 0.5 μm or less in addition to the above diffraction peak. The particle size can be observed with an electron microscope. Those having a particle size larger than that in the process of surface treatment have a defect that black spots called black spots are likely to appear in the image. Bragg angle 2θ 27.2 ± in CuKα characteristic X-ray diffraction of the present invention
Although titanyl phthalocyanines having a maximum peak at 0.2 degree are highly sensitive, it is necessary to pay attention to the selection of a dispersion solvent because they are metastable crystals.

By coating with a polymer insoluble in the dispersion medium, it was possible to stabilize the dispersion for a long period of time. Then, the constitution of the present invention results in coating the pigment with a polymer different from the main binder of the photoconductor, which contributes to the improvement of the stability of the photoconductor when it is repeatedly used. That is, by independently selecting the pigment-coated polymer, unlike the conventional polymer for the binder of the photoconductor, the polymer species can be selected for the purpose of protecting the pigment, apart from the restrictions such as film physical properties. For example,
It is also possible to select a polymer containing polyvinyl alcohol, which is known as a polymer having low oxygen permeability, as its component. Then, it is considered that it is effective against the deterioration of potential characteristics at the time of repetition, the influence of humidity, etc., which is considered to be caused by ozone and the like.

Various kinds of pigment dispersion solvents can be selected,
Examples thereof include tetrahydrofuran, cyclohexanone, methyl ethyl ketone, dichloroethane, dichloromethane, and alcohols and esters. The polymer insoluble in the dispersion medium may be any polymer which is insoluble in any one of the dispersion media, but is preferably a polymer insoluble in dichloroethane or toluene. The polymer insoluble in dichloroethane or toluene means a substance which is insoluble at a concentration of 0.5% or more at room temperature, and preferable examples thereof include a crosslinked polymer and a copolymer containing polyvinyl alcohol or polyamide as its component. The cross-linked polymer is a polymer that does not dissolve in a solvent when it is three-dimensionally cross-linked, such as those that self-crosslink by heating such as phenol resin, melamine resin, and urea resin, and urethane resin, epoxy resin, and silicon-modified epoxy resin. , Polyester-melamine resin and the like that can be crosslinked by condensation with other components. It is considered that the coating with these resins hindered the permeation of ozone and the like and had a favorable effect on the repeated use of the photoconductor.

The second object of the present invention is also to provide a dispersion for inexpensively producing a photoreceptor by using a pigment coated with a polymer insoluble in the dispersion medium. The preferred one was achieved by coating the titanyl phthalocyanine pigment with a polymer which is insoluble in dichloroethane or toluene. Dichloroethane and toluene are solvents that dissolve many polymers (used as a binder) together with THF (tetrahydrofuran), dichloromethane, cyclohexanone, etc. Because of their good affinity with pigments, they are often used to make stable dispersions. is there. Especially in electrophotography, as an additive other than pigments, electron transport materials (described later)
When adding aromatic compounds, it is effective because of its dissolving power. However, there is a problem that these solvents are likely to undergo crystal conversion for compounds having many crystal forms such as phthalocyanines due to their affinity for the surface. If the product coated with a polymer film is used as a dispersion liquid for an electrophotographic photoreceptor, the possibility of crystal conversion is reduced, the dispersion liquid becomes stable for a long time, and the manufacturing cost can be reduced.

Another method of the present invention solves the problem by hydrophobizing the pigment by surface treatment.
As the treating agent used for the surface treatment of the present invention, a coupling agent used for general surface treatment can be used. For example, many of them, such as aluminum coupling agents, titanium coupling agents, and silane coupling agents, have a metal alkoxide structure as a part thereof. The example of the compound is shown below.

[0017]

[Chemical 1]

[0018]

[Chemical 2]

[0019]

[Chemical 3]

[0020]

[Chemical 4]

The term "hydrophobicized" as used in the present invention means that the pigment becomes harder to be wetted with water than before treatment. For example, when the pigment which is wetted and settled with water alone is subjected to a surface treatment, the pigment does not get wet and floats on the water surface. Like The surface of the pigment was objectively hydrophobized by observing the amount of methanol required to start the settling, when the pigments that float without being wet by the water alone get wet and settle in the mixed solution of methanol / water. You can know Examples are given in the examples of this patent. The surface treatment agent does not necessarily cover the entire surface of the titanyl phthalocyanine particles. Therefore, even if the vicinity of the titanyl phthalocyanine particles is coated with the coupling agent, it is still affected by the humidity of the atmosphere. However, the surface treatment of the present invention increases the moisture resistance by making the surface of the pigment particle more hydrophobic.

Further, according to the present invention, the particle diameter of the surface-treated pigment is
It is also an essential requirement that the thickness be 0.1 μ or less. In the surface treatment, when the particles are weakly dispersed and agglomerated, the surface treatment (apparently, the particle diameter is large) appears as an image defect in the electrophotographic photoreceptor.

Regarding the titanyl phthalocyanine crystals having a maximum peak at 27.2 ° ± 0.2 °, those particularly preferred in the present invention are the crystals obtained through acid paste treatment in the process of synthesis.

The acid paste step is a step in which the pigment is dissolved in sulfuric acid, filtered to remove the remaining insoluble matter, and then poured into water to be made amorphous. The acid paste treatment referred to in the present invention has a broad meaning including an operation of pouring into an organic solvent containing water other than water to directly obtain the crystal form of the present invention, in addition to the above-mentioned operation of pouring into water.

Among the titanyl phthalocyanine crystals of the present invention, those obtained through the acid paste step in the process of synthesis show particularly good performance, probably because water-soluble impurities have been removed or once acid-dissolved. By going through the process,
This may be because other undesirable crystal forms formed during the synthesis of phthalocyanine disappear and are not mixed.

[0026]

The synthesis of the titanyl phthalocyanine of the present invention can be made according to the patents already published (JP-A-3-35245, JP-A-3-128973, JP-A-2-309362,
JP-A-3-255456). It can also be made by making a seed crystal and amplifying it.

From the X-ray diffraction spectrum, among the titanyl phthalocyanine crystals of the present invention, particularly preferable ones are selected from the following three. That is, the Bragg angle (2θ ± 0.
2 degree) has a maximum peak of 27.2 degree and at least 9.6
, A crystal having a peak at 24.1 degrees or at least 9.0 degrees in addition to 27.2 degrees, a crystal having a peak at 14.2 degrees, 24.0 degrees, or a maximum peak at 27.2 degrees and at least 7.5 degrees, 9.2 degrees, 10.5 other The three crystals have peaks at degrees 13.1, 13.0, and 26.2 degrees.

The measurement conditions of the X-ray diffraction spectrum are shown below. This measurement was performed by the usual powder method using "JDX-8200" (manufactured by JEOL Ltd.).

X-ray tube Cu voltage 40.0 KV current 100 mA start angle 6.0 deg. Stop angle 35.0 deg. Measurement time 0.50 sec. These crystal forms are all known in the laminated photoreceptor as far as the X-ray diffraction spectrum is seen. It is a thing. (JP-A-64
-17066, JP-A-2-309362, JP-A-3-35245, and JP-A-3-255456) However, these materials are metastable crystals although they have excellent sensitivity, and are easily thermally converted into A type. There are problems such as transfer. The transition temperature is, for example, maximum at 27.2 ° C and 250 ° C for other crystals having peaks at 9.6 ° and 24.1 °.
Therefore, there is no practical problem after it is completed as a photoconductor. However, during its production, the stability of the dispersion is affected, causing problems for long-term storage. This leads to an increase in cost in the mainstream dip coating. In particular, in the above-mentioned positively charged photoreceptor, the layer containing the pigment is the upper layer, and the mechanical properties of the pigment dispersion layer as a film are important.
Therefore, in such a photoreceptor, the selection range of the binder is limited, and as a result, the selection of the dispersion solvent in the production tends to be limited. For Y-type titanyl phthalocyanine, it is not allowed to use only a solvent in which crystal conversion does not easily occur, which is a serious problem.

The coating of sensitive but metastable crystals with the dichloroethane or toluene insoluble polymer of the present invention provides stability for repeated use of the photoreceptor while at the same time extending the life of the dispersion and making it. The cost will be reduced. Further, the constitutional requirements as the photoconductor of the present invention will be described.

The layer structure of the photoconductor of the present invention may be a known one. That is, the layer structure of a normal laminated photoconductor can be used for negative charging photosensitivity ((1) in FIG. 1,
(2)). For example, a subbing layer 4 is provided on a conductive substrate 1 made of aluminum or the like, and then a phthalocyanine wrapped with a crosslinked polymer of the present invention is dispersed in the charge generation layer 2 (CG
L) is provided, and the charge transport layer 3 (CTL) containing the charge transport material (CTM) is provided thereon. In some cases, a conductive layer 6 may be provided between the conductive substrate and the undercoat layer. Further, the protective layer 5 may be provided on the uppermost layer. In addition, the above-mentioned laminated photoreceptor (in this case, an electron transport material is used for the charge transport layer) can be used for positive charging, and the laminated photoreceptor having the reverse layer structure ((3) in FIG. 1,
(4)), and further, a single-layer photoconductor can be used ((5) and (6) in FIG. 1).

For each layer of these layer constitutions, those already known in the electrophotographic photoreceptor technology can be used alone or in combination. For the undercoat layer, for example, polyamide, polyester, polyacrylic, polymethacrylic,
Polyester, polyvinyl acetate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-maleic anhydride copolymer,
Alternatively, many kinds of modified polyolefin resin can be cited. Examples of the conductive layer include titanium oxide, tin oxide, and aluminum oxide dispersed in a binder. The charge generation layer (CGL) is a layer composed of a dispersion of phthalocyanines encapsulated by the cross-linked polymer of the present invention. In addition to the pigment, an azo pigment, a perylene pigment, a polycyclic quinone pigment, a squarium pigment, etc. are added. May be. As the binder of CGL, polycarbonate, polyvinyl butyral, polyvinyl formal, silicone resin, cellulose resin, and substances derived therefrom can be used in addition to the substances mentioned in the undercoat layer. The charge transport layer (CTL) contains a charge transport material (CTM). Known compounds such as amine compounds which are hole transporting substances, triphenylamine styryl compounds, hydrazones, pyrazolines, and diphenylamine derivatives can be used for negative charging. An electron transporting substance is used for positive charging. In the photoconductors of (3) and (4) shown in FIGS. 1A and 1B having the reverse layer structure, the above hole transporting substance can be used even for positive charging. CTL
Any binder may be used as the binder in the protective layer, and for example, the binder used in the undercoat layer or CGL may be used. When a single-layer photoconductor is used for positive charging, the charge generation layer contains a charge-transporting substance (hole and electron-transporting substance) in the layer in addition to the CGL technique described in the above-mentioned laminated photoconductor. be able to.

As the hole-transporting substance added to the inside of CGL, those described for the laminated photoreceptor can be used. Further, as the electron transporting material, in addition to the materials used in the laminated photoreceptor, compounds having poor solubility which are conventionally known as electron accepting materials can be used. Examples of such an electron transporting material include fluorenone derivatives, benzoquinone derivatives, maleic anhydride, nitro compounds, dibenzothiophene derivatives, aromatic carboxylic acids and the like.

An antioxidant or an ultraviolet absorber may be added to any layer of the electrophotographic photoreceptor of the present invention for the purpose of improving durability. Examples of these compounds include hindered phenol compounds, hindered amine compounds, hydroquinones, organic sulfur compounds, organic phosphorus compounds, and benzotriazole derivatives known by the trade name Tinuvin (Ciba Geigy).

[0035]

EXAMPLES Examples will be given, but the present invention is not limited thereto.

The synthesis example will be specifically described below.

Synthesis Example (Synthesis Example 1 of Pigment) 142 g of titanium butoxide is dissolved in 1.5 of 1-chlornaphthalene. Then, 203 g of 2.3-diiminoisoindoline is added to this and heated at 200 ° C. for 4 hours.

After cooling, the precipitated crystals were filtered and washed with chlornaphthalene and methanol to obtain crude titanyl phthalocyanine. Then, 100 g of this crystal was added to 1200 m of concentrated sulfuric acid.
It was dissolved in 1 and poured into pure water 25 to precipitate crystals. It was thoroughly washed with water to obtain an amorphous titanyl phthalocyanine wet paste. This wet paste (solid content
100% of 12%) was dispersed in a mixed solution of 300 ml of cyclohexanone and 100 ml of water, stirred for 24 hours, poured into 100 ml of methanol and the precipitated crystals were collected by filtration.

The X-ray diffraction pattern is shown in FIG. Maximum peak 27.2
And has clear peaks at 9.6 degrees and 24.1 degrees. TiOPc-1 (Synthesis example 2 of pigment) 18.0 g of titanium tetrachloride was dropped into a mixture of 40 g of phthalodinitrile and 500 ml of α-chloronaphthalene under a nitrogen stream, and the mixture was stirred at 250 ° C for 3 hours to complete the reaction. Let Then, it was left to cool to room temperature and filtered to obtain a product dichlorotitanium phthalocyanine. The obtained dichlorotitanium phthalocyanine was washed with water at 80 ° C. also for hydrolysis to obtain a crude titanyl phthalocyanine.

Then, 10 g of this crystal was dissolved in 150 ml of concentrated sulfuric acid and poured into pure water 3 to precipitate the crystal.

After thorough washing with water, an amorphous titanyl phthalocyanine wet paste was obtained. This was suspended in methanol at room temperature, left overnight, filtered and dried under reduced pressure to obtain low crystalline titanyl phthalocyanine.

Then, this product was n-
Butyl ether was added and milling was performed at room temperature for 20 hours. The solid content was taken out from the dispersion, sufficiently washed with methanol and then with water, and dried to obtain a titanyl phthalocyanine crystal of the present invention. The X-ray diffraction pattern is shown in FIG. Maximum peak at 27.1 degrees, described as TiOPc-2, other, 9.0 degrees, 14.2 degrees, 24.
It has a strong peak at 0 degree.

(Pigment Synthesis Example 3) 10 g of the crude phthalocyanine obtained in Pigment Synthesis Example 2 was dissolved in 150 ml of concentrated sulfuric acid to prepare pure water 3
To precipitate crystals. After thoroughly washing with water, amorphous titanyl phthalocyanine was obtained. 10 g of the amorphous titanyl phthalocyanine thus obtained was mixed with 15 g of sodium chloride and 7 ml of diethylene glycol, and milled for 60 hours in an automatic mortar under heating at 80 ° C. Then, it was thoroughly washed with water to remove sodium chloride and diethylene glycol, and dried under reduced pressure. Next, cyclohexanone and glass beads were added to this product and the mixture was subjected to a sand mill treatment to obtain a titanyl phthalocyanine crystal of the present invention. The X-ray diffraction pattern is shown in FIG.

Maximum peak at 27.1 degrees, others, 7.5 degrees, 9.2
It has peaks at degrees, 10.5 degrees, 13.1 degrees, 15.0 degrees, and 26.2 degrees.
It is written as TiOPc-3.

(Capsule Synthesis Example 1) 10 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 and 0.5 g (solid content) of a phenol resin (Sumirac PC-1 Sumitomo Chemical Co., Ltd.) were mixed in 250 ml of isopropanol, and ultrasonically mixed with 1 Time dispersed. This dispersion was placed in a flask, and 440 ml of isoparaffin solvent (Isopar G, Exxon Chemical) was added with stirring. Then, isopropanol was distilled off under normal pressure while heating and stirring at 100 ° C. for 4 hours to cure the phenol resin. After allowing to cool, it was filtered and washed with hexane to obtain 10.2 g of encapsulated titanyl phthalocyanine. Below capsule TiO
It is written as Pc-11.

(Capsule Synthesis Example 2) 10 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 and epoxy-modified silicone resin (ES-1001N Shin-Etsu Chemical Co., Ltd.) and 0.5 g (solid content) were added to 250 ml of methyl isopropyl ketone (MIPK). Mix and sonicate for 1 hour. Then, this was transferred to a flask and 440 ml of isoparaffin solvent (Isopar G, Exxon Chemical) was added with stirring. Then, 0.1 g of titanium tetraisopropoxide dissolved in 5 ml of Isopar G was added thereto. After stirring at room temperature for 30 minutes, under reduced pressure M
Heat while distilling off IPK, and after confirming 180 ml of distillate,
It was heated at 90 ° C. for another 4 hours to cure. After allowing to cool, it was filtered and washed with hexane to obtain 10.3 g of encapsulated titanyl phthalocyanine. Hereinafter referred to as capsule TIOPc-12.

(Capsule Synthesis Example 3) 20 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 and 0.8 g (solid content) of polyester resin (Almatex P-645 Mitsui Toatsu Chemical) and melamine resin (Uban 2061 Mitsui Higashi). 0.20 g (solid content) is mixed with 300 ml of MIPK and dispersed by ultrasonic wave for 1 hour. Then, this was transferred to a flask, and 800 ml of isoparaffin solvent (Isopar G, Exxon Chemical) was added with stirring. After stirring at room temperature for 30 minutes, M under normal pressure
The IPK was heated while distilling off. 190 ml is distilled off until the liquid temperature reaches 120 ° C. Heat at 120 ° C for 2 hours to complete curing. After allowing to cool, it was filtered and washed with hexane to obtain 20.5 g of encapsulated titanyl phthalocyanine.
Hereinafter referred to as capsule TiOPc-13.

By the same procedure, the titanyl phthalocyanine of Synthesis Example 2 and the titanyl phthalocyanine of Synthesis Example 3 were encapsulated, and each of them was encapsulated into TIPc-21 to 23 capsules.
It is written as TiOPc-31-33.

(Capsule Synthesis Example 4) 2.0 g of methoxymethylol-modified nylon (Daiamide X1874M Daicel Hüls) was dissolved in 300 ml of isopropanol in advance. Then, 20 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 was added thereto, and the mixture was ultrasonically dispersed for 1 hour. 1000 parts of isoparaffin solvent (Isoper G, Exxon Chemical)
ml was added with stirring. Precipitated crystals were collected by filtration, washed with hexane and encapsulated in titanyl phthalocyanine 2
Obtained 1.5 g. It is referred to as a capsule TIOPc-14.

(Capsule Synthesis Example 5) 2.0 g of copolymer nylon (CM8000 Toray) was dissolved in 100 ml of methanol in advance. To this, 100 ml of isopropanol was further added, and then 20 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 was added, and the mixture was ultrasonically dispersed for 1 hour.

To this, 1000 ml of isoparaffin solvent (Isopar G, Exxon Chemical) was added with stirring.

The precipitated crystals were collected by filtration and washed with hexane to obtain 21.8 g of encapsulated titanyl phthalocyanine.
It is referred to as a capsule TIOPc-15.

(Capsule Synthesis Example 6) 1.0 g of an ethylene vinyl alcohol copolymer (Soarnol Nippon Synthetic Chemical Industry Co., Ltd.) is heated and dissolved in a mixed liquid of 100 ml of isopropanol and 100 ml of water. 20 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 was added thereto, and the mixture was ultrasonically dispersed for 1 hour. Then, 10 l of water was added with stirring. The precipitated crystals were collected by filtration to obtain 20.6 g of encapsulated titanyl phthalocyanine. It is referred to as a capsule TiOPc-16.

By the same procedure, the titanyl phthalocyanine of Synthesis Example 2 and the titanyl phthalocyanine of Synthesis Example 3 were encapsulated to form capsules TiOPc-24 to 26 and capsule Ti, respectively.
It is described as OPc-34 to 36.

Evaluation 100 mg of the encapsulated pigment was ultrasonically dispersed in 5 ml of solvent. Then put this in a 60 ° C constant temperature box,
The change in crystal type was observed over time. The results are shown in Table 1.

[0056]

[Table 1]

○ ・ ・ ・ Maintain original crystal form × ・ ・ ・ Crystal form change 6h ・ ・ ・ 6 hours 1d ・ ・ ・ 1 day 3d ・ ・ ・ 3 days 1w ・ ・ ・ 1 week ie original TiOPc-1 ~ 3 is stable when special t-butyl acetate is used as a solvent, but crystal change is observed within 6 hours when heated in dichloroethane or toluene. On the contrary, encapsulated TiOPc tends to be stabilized. Although it seems to be storable for only 1 to 3 days, this is considered to correspond to 1 month or more at room temperature.

The data of TiOPc-1 to 3 supported at room temperature are shown below.

[0059] Both dichloroethane and toluene, which have undergone crystal transition within 60 hours at 60 ° C, are stable for more than 1 week at room temperature. From this, it is expected that the encapsulated product will be stable for more than one month.

Evaluation The solvent resistance stability was also observed for those coated with a non-crosslinked resin (Capsule Synthesis Examples 4 to 6). M is a ketone-based solvent
It was dispersed in EK (methyl ethyl ketone) and placed in a constant temperature box in the same manner to see the crystal stability at 50 ° C. In Table 2, x indicates that the crystal type was changed.

[0061]

[Table 2]

All of the encapsulated products show better stability than untreated products.

Next, a specific example of the surface treatment will be shown.

(Surface Treatment Example 1) 10 g of the titanyl phthalocyanine of the present invention obtained in Synthetic Example 1 of pigment and 1.0 g of an aluminum coupling agent (Exemplary compound 15, Plenact ALM Ajinomoto) were mixed with 250 ml of carbon tetrachloride, and the mixture was ultrasonicated. Dispersed for 1 hour.
This dispersion was placed in a flask and heated and stirred at 60 to 70 ° C for 4 hours. Then, methanol was added to this substance while stirring, and the precipitated crystals were collected by filtration. Hereinafter, it will be referred to as hydrophobized TiOPc-11. When observed with an electron microscope, the shape of this product was a sphere of about 0.1 μ.

(Surface Treatment Example 2) 10 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 and 1.0 g of a titanium coupling agent (Exemplary compound 1, Preneact KR-TTS Ajinomoto).
Was mixed with 250 ml of carbon tetrachloride and ultrasonically dispersed for 1 hour. This dispersion was placed in a flask and heated and stirred at 60 to 70 ° C for 4 hours. Then, methanol was added to this substance while stirring, and the precipitated crystals were collected by filtration. Below, hydrophobized TiOPc-12
Is written. When observed with an electron microscope, the shape of this product was a sphere of about 0.1 μ.

(Surface Treatment Example 3) 10 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 and 1.0 g of a titanium coupling agent (Exemplary Compound 14, Plenact KR-41B Ajinomoto).
Was mixed with 250 ml of carbon tetrachloride and ultrasonically dispersed for 1 hour. This dispersion was placed in a flask and heated and stirred at 60 to 70 ° C for 4 hours. Then, methanol was added to this substance while stirring, and the precipitated crystals were collected by filtration. Below, hydrophobized TiOPc-13
Is written. When observed with an electron microscope, the shape of this product was a sphere of about 0.1 μ.

(Surface Treatment Examples 4 to 7) The titanyl phthalocyanine of Synthetic Example 2 and the titanyl phthalocyanine of Synthetic Example 3 were encapsulated in exactly the same procedure, and encapsulated TiOP, respectively.
c-21 to 22, Capsule TiOPc-31 to 32. When observed with an electron microscope, all of these shapes were spherical with a diameter of 0.1 μm or less.

(Comparative Surface Treatment 1) 10 g of the titanyl phthalocyanine of the present invention obtained in Pigment Synthesis Example 1 and 3.0 g of an aluminum coupling agent (Exemplary compound 15, Plenact ALM Ajinomoto).
Was mixed with 250 ml of chloroform and stirred for 1 hour. This dispersion was placed in a flask and subjected to ultrasonic waves while heating at 60 to 70 ° C for 4 hours. Then, this product is methanol 1,000m
It was poured into 1 and the precipitated crystal was collected by filtration. Below, comparative hydrophobization
It is written as TiOPc-14. When observed with an electron microscope, many aggregates of 0.5 μm or more were observed in this product.

Evaluation Hydrophobicity Test The surface-treated pigment was placed in a test tube, an aqueous methanol solution having a different methanol concentration was added, and the mixture was stirred for a while to observe whether or not it settled. (× ... buoyancy ◯ ... sedimentation) The results are shown in Table 3.

[0070]

[Table 3]

The surface of each of the highly sensitive crystalline TiOPc-1 to 3 is hydrophilized to such an extent that water alone precipitates.
On the other hand, the surface-hydrophobicized TiOPc-11 to 32 do not settle in water alone, but settle only when 10% or more of methanol is added. This shows that the pigment surface is hydrophobized.

The present invention will be described below with reference to examples in which a photosensitive member is produced by using the above crystal.

Example 1 20 parts by weight of encapsulated TiOPc-11 powder, 50 parts by weight of bisphenol type polycarbonate resin (Z200 Mitsubishi Gas Chemical Co., Inc.), and 300 parts by weight of dichloroethane were added to glass beads having a particle diameter of 2.4 mm to 4.0 mm (HIBE No. 8 OHARA). And dispersed for 6 hours to prepare a dispersion liquid.

This dispersion was dip-coated on a drum having a diameter of 180 mm and dried at 120 ° C. for 1 hour to form a photosensitive layer of 17 μm. In the same manner, photoconductors were prepared for the capsules TOPc-12 to 33 and the comparative TIPc-1 to 3 mentioned in the above-mentioned synthesis examples and encapsulation examples.

The photoconductor was subjected to a normal temperature and normal humidity (20
When the running test was performed under the conditions of 60 ° C and 60%), the encapsulated TiOPc-11 to 33 had the same electrical characteristics before and after the repetition, and the image was good.
The image was fogged because the unexposed area potential decreased. The results are shown in Table 4.

Unexposed area potential Vh, exposed area potential Vl, image, ◯ Good Δ Fog occurred

[0077]

[Table 4]

Example 2 20 parts by weight of encapsulated TiOPc-14 powder, 40 parts by weight of polyester binder (ALMATEX P-645 Mitsui Toatsu Chemicals) (solid content), and 10 parts by weight of melamine resin (Uban 2061 Mitsui Toatsu Chemicals). (Solid content) cyclohexanone 30
Along with 0 part by weight, glass beads having a particle diameter of 2.4 mm to 4.0 mm (HIBY No. 8 OHARA) were used for dispersion for 6 hours to prepare a dispersion liquid. Dip coating this dispersion on a drum with a diameter of 180 mm, 1
It was dried at 20 ° C. for 1 hour to form a 17 μm photosensitive layer. In the same manner, the capsules listed in the encapsulation example TIPc-15, 24, 25,
Photoconductors were also prepared for 34, 35 and comparative TiOPc-1-3.

The photoconductor was mounted on an improved machine of "Konica 9028" (using a semiconductor laser light source of Konica Corporation), and was repeated 5000 times in a low temperature and low humidity environment (10 ° C 30%). The results are shown in Table 5, which is the capsule of the present invention TIPc-15.
˜36 was stable, but the comparative TiOPc-1 to 3 had the exposed portion potential Vl increased and the image density decreased.

Unexposed area potential Vh, exposed area potential Vl, solid black density Bl

[0081]

[Table 5]

Example 3 Capsule TiOPc-16 powder was used and coated and dried in the same manner as in Example 2 to form a photosensitive layer. Similarly, the capsules TIPc-26, 36 and the comparative TOPc-1 to 1 mentioned in the encapsulation example were compared.
For 3 as well, a photoconductor was prepared.

The photoconductor was left in an ozone atmosphere of 100 ppm at 50 ° C. for 1 hour, and the photoconductor before and after the exposure to the explosion was mounted on a modified machine of “Konica 9028” (Konica Corporation, using a semiconductor laser light source), and the potential and the image were compared. As shown in Table 6, the capsules of the present invention coated with an ethylene PVA resin having a high oxygen barrier property, TIPc-16 to 36, were stable, but the comparative TIOPC-.
In Nos. 1 to 3, the surface potential was lowered after ozone exposure and fine lines were blurred in the image.

Image of unexposed portion potential Vh, exposed portion potential Vl ○ Good △ Bleeding in fine lines

[0085]

[Table 6]

Example 4 20 parts by weight of the above-mentioned hydrophobized TiOPc-11 powder, 40 parts by weight of a polyester resin "ALMATEX P-645; Mitsui Toatsu Kagaku", 10 parts by weight of melamine resin "Uban 20HS; Mitsui Toatsu Kagaku" ,
250 parts by weight of cyclohexanone were dispersed for 10 hours together with glass beads "HIVY No8 OHARA" having a particle diameter of 2.4 to 4.0 mm to prepare a dispersion liquid. This dispersion was applied onto a drum having a diameter of 180 mm by dip coating and dried at 120 ° C. for 1 hour to form a photosensitive layer of 15 μm.

Photoreceptors were prepared in the same manner using the hydrophobized TIPc-12 to 32 mentioned in the above-mentioned synthesis examples and surface treatment examples and the non-hydrophobized TOPc-1 to TIPc-1 to 3 as comparative examples.

The obtained sample was mounted on a modified "Konica 9028" (Konica Corporation, using a semiconductor laser light source) in an environment of 20 ° C. and 50% RH, the grid voltage Vg was adjusted to 800 V, and the unexposed area was adjusted. Potential Vh and potential Vl of exposed area during light irradiation
Was measured.

Next, the sample was transferred to an environment of 30 ° C. and 80% RH and sufficiently adapted to the environment, and then Vh and Vl were measured under the above-mentioned conditions.

Further, reversal development was carried out to observe the image.

[0091]

[Table 7]

Image ○: Good Δ: Fogging
X: with black spots The photoconductor using the hydrophobicized TiOPc of the present invention is an excellent photoconductor with a small difference in the receptive potential Vh between high temperature and high humidity and normal temperature and normal humidity. On the other hand, the untreated surface of TiOPc
The comparative sample using is large in Vh due to environmental changes. As a result, the photoconductor using surface-untreated TiOPc causes fog under high temperature and high humidity. In addition, the comparatively hydrophobized TiOPc-14 having a large particle size has an image defect called black spot. On the other hand, the surface-treated phthalocyanine-containing photoconductor of the present invention gives a good image both under normal temperature and normal humidity and under high temperature and high humidity.

[0093]

Industrial Applicability According to the present invention, it is possible to provide a printer and a digital photoconductor which have high sensitivity, little deterioration in performance upon repeated use, and little pollution or environmental problems. In particular, it is possible to provide a photoconductor with less performance deterioration when repeatedly used in the positive charging specification. The second effect of the present invention is to provide a stable dispersion liquid for inexpensively producing the above-mentioned photoreceptor.

[Brief description of drawings]

FIG. 1 is a typical cross-sectional view of a photoconductor of the present invention.

FIG. 2 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment crystal according to the present invention.

FIG. 3 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment crystal according to the present invention.

FIG. 4 is an X-ray diffraction spectrum of a titanyl phthalocyanine pigment crystal according to the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Charge Generation Layer (CGL) 3 Charge Transport Layer (CTL) 4 Undercoat Layer 5 Protective Layer 6 Conductive Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Eto, Konica stock company, 2970 Ishikawa-cho, Hachioji, Tokyo (72) Inventor Hiroyuki Moriguchi, 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock, company

Claims (13)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein the Bragg angle 2θ in X-ray diffraction of CuKα characteristic of which surface is coated with a polymer insoluble in a dispersion medium is 27.2 ± 0.2 degrees. An electrophotographic photosensitive member comprising a titanyl phthalocyanine pigment crystal having a maximum peak in the. 2. The electrophotographic photosensitive member according to claim 1, wherein the polymer insoluble in the dispersion medium is a polymer insoluble in dichloroethane or toluene. 3. The electrophotographic photosensitive member according to claim 2, which is a polymer in which a polymer insoluble in dichloroethane or toluene is crosslinked. 4. The electrophotographic photosensitive member according to claim 2, wherein the polymer insoluble in dichloroethane or toluene has a polyvinyl alcohol structure as a part thereof. 5. The electrophotographic photosensitive member according to claim 2, wherein the polymer insoluble in dichloroethane or toluene has a polyamide structure as a part thereof. 6. The electrophotographic photosensitive member according to claim 1, wherein the titanyl phthalocyanine crystal is synthesized through an acid paste treatment step. 7. The photoreceptor according to claim 6, wherein the Bragg angle (2θ ± 0.2 degrees) has a maximum peak at 27.2 degrees, and the titanyl phthalocyanine crystal synthesized through the acid paste treatment step has a peak of 27.2 degrees. At least 9.6 degrees, 24.1
Crystal having a peak at 2 degrees, at least 9.0 degrees, 14.2 degrees, crystals having a peak at 24.0 degrees, or at least 7.5 degrees, 9.2 degrees, 10.5 degrees, 13.1 other than 27.2 degrees
A photoconductor characterized by being selected from crystals having peaks at 15.0 degrees, 15.0 degrees and 26.2 degrees. 8. The electrophotographic developing method according to claim 1, wherein the electrophotographic photosensitive member is applied to a positive charging process. 9. A dispersion liquid containing a titanyl phthalocyanine pigment crystal, which has a maximum Bragg angle 2θ in CuKα characteristic X-ray diffraction of 27.2 ± 0.2 degrees and is coated with a crosslinked polymer film. 10. An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer provided on the surface thereof.
Bragg angle 2θ in X-ray diffraction of α characteristics is 27.2 ± 0.
An electrophotographic photoreceptor comprising a titanyl phthalocyanine crystal having a maximum peak at 2 degrees and a particle size of 0.5 μm or less. 11. The electrophotographic developing method according to claim 10, wherein the electrophotographic photosensitive member is applied to a positive charging process. 12. The electrophotographic photosensitive member according to claim 10, wherein a titanyl phthalocyanine crystal having a maximum peak at a Bragg angle of 2θ27.2 ± 0.2 degrees is synthesized through an acid paste treatment step. body. 13. The photoconductor according to claim 12, wherein the Bragg angle (2θ ± 0.2 degrees) has a maximum peak at 27.2 degrees,
The titanyl phthalocyanine crystals synthesized through the acid paste treatment process were at least 9.6 degrees and 27.2 degrees in addition to 27.2 degrees.
A crystal having a peak at 4.1 degrees, or a crystal having a peak at at least 9.0 degrees, 14.2 degrees, and 24.0 degrees in addition to 27.2 degrees,
Or at least 7.5 degrees, 9.2 degrees, 10.5 degrees in addition to 27.2 degrees,
A photoconductor characterized by being selected from crystals having peaks at 13.1 degrees, 15.0 degrees, and 26.2 degrees.