KR100510871B1 - Coating Liquid for Charge Generating and Delivering Layer in Electrophotographic Photoconductor - Google Patents

Abstract

The present invention relates to a charge generating transport coating liquid comprising an X-type metal-free phthalocyanine, a perylene pigment, a butadiene-based hole transport material, a diphenoquinone-based electron transport material, a binder resin, and an organic solvent. The compatibility between components is excellent and there is no change over time even in long-term use, and the single layer electrostatic electrophotographic photosensitive member including the charge generating transport layer formed therefrom has excellent sensitivity and excellent image quality.

Description

Coating Liquid for Charge Generating and Delivering Layer in Electrophotographic Photoconductor}

The present invention relates to a charge generating transport coating liquid for an electrophotographic photosensitive member, and more particularly, to a charge containing a metal-free phthalocyanine and perylene pigment, butadiene-based hole transport material, diphenoquinone-based electron transport material, a binder resin and an organic solvent The present invention relates to an electrophotographic photosensitive member having a generation transport coating liquid and a charge generation transport layer formed using the same, which exhibits excellent sensitivity and image practical characteristics.

As electrophotographic photoconductors, inorganic photoconductors mainly composed of inorganic photoconductive materials such as selenium, zinc oxide, and cadmium sulfide have been widely used. However, these inorganic photoconductors have been insufficient in light sensitivity, durability, and environmental problems. Attempts have been made to use organic photoconductive materials in electrophotographic photosensitive layers that can obtain various properties by changing chemical or crystal structures, and research and development have been actively conducted. Organic photoconductive materials have the advantage of being easy to control the properties of the material itself in the synthesis process and the production of the photoconductor is relatively simple.

On the other hand, the photoreceptor can be divided into the negative charging method and the positive charging method according to the charging method. Currently, the photosensitive member adopts the negative charging method that charges and exposes the negative charge on the drum surface, but ozone by applying the negative charge is used. Recently, research on the photosensitive member of the positive charging method has been actively conducted again due to disadvantages such as a problem of occurrence and limitation of resolution improvement.

The positive charging method is a method of exposing the surface of the photoconductor by applying a positive charge, and the ozone generation amount is remarkably low, which is environmentally friendly and has a higher resolution than the secondary charging method. R & D on transportation materials is relatively weak, and there are restrictions on using it.

In addition, the photoreceptor can be divided into a single layer type and a stacked type according to the configuration of the layer, the single layer type is characterized in that the charge generation and charge transport takes place in the same layer, the stacked type is characterized in that the charge generation and charge transport occurs in separate layers, respectively. to be.

Among the organic photoconductive materials, azo compounds, phthalocyanine compounds, azulenium salt compounds, pyryllium salt compounds, naphthoquinone compounds, and the like are known as substances having sensitivity to semiconductor laser light, and among these, particularly phthalocyanine compounds. Compounds are widely used as charge generating materials for electrophotographic photosensitive members because of their chemical and physical stability and excellent light sensitivity. For example, there are copper phthalocyanine, metal-free phthalocyanine, chloroaluminum phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, chlorogermanium phthalocyanine, vanadil oxide phthalocyanine, titanyl oxide phthalocyanine, hydroxygermanium phthalocyanine and the like.

The phthalocyanine-based charge generator can be used in combination with an azo or perylene-based charge generator, and the charge generation transport coating liquid prepared by dispersing it in an organic solvent together with a hole transport material, an electron transport material, and a binder resin can be used on an aluminum substrate. It is applied to and coated on the film. However, even if the charge generation transport coating liquid is stable immediately after the preparation of the coating liquid, the charge generating material in the coating liquid may cause crystal growth, agglomeration, and coarse particle formation after a predetermined time. Also, the charge generating material, the hole transport material, Crystallization or gelation may occur due to lack of solubility or compatibility between the electron transport material, binder resin, solvent, and additives, resulting in deterioration of electrophotographic properties or nonuniformity of local electrical properties in the coating. Since the above causes black spots, image defects, and resolution degradation, there is a demand for a charge generation transport coating liquid that is stable against crystal change, crystal growth, and aggregation of the charge generating material and has excellent compatibility between components.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, using a mixed or simple mixed charge generating material of the phthalocyanine-based pigment for the p-type semiconductor and the perylene-based pigment for the n-type semiconductor and An object of the present invention is to provide a single-layer positive electrostatic photosensitive member having excellent sensitivity characteristics, potential retention, and image quality characteristics by using a hole transport material, an electron transport material, etc. having excellent properties.

That is, one aspect of the present invention is a single-layer positive electrode type including a X-type metal-free phthalocyanine of the formula (1), a perylene pigment of the formula (2), a butadiene-based hole transport material, a diphenoquinone-based electron transport material, a binder resin and an organic solvent Provide a charge generating transport coating solution for an electrophotographic photosensitive member:

[Formula 1]

In the above formula, R1 to R16 are each independently a hydrogen atom, a halogen atom, a nitro group, an alkyl group or an alkoxy group;

[Formula 2]

In the above formula, R17 and R18 are each independently a methyl group, hydroxyethyl group, ethyl group, methoxyethyl group, propyl group, butyl group, pyridyl group, isopentyl group, pentyl group, hexyl group, isohexyl group, dichlorophenyl group, chlorophenyl group , Phenyl group, methylpyridyl group, cyclohexyl group, benzthiazole group, benzyl group, methoxyphenyl group, phenylethyl group or quinoline group.

Another aspect of the present invention provides a single-layer positive electrostatic photosensitive member including a charge generating transport layer formed using the charge generating transport coating solution.

As a result of intensive research, the present inventors have used the metal-free phthalocyanine and the perylene-based pigments together to determine the crystal change, such as aggregation, precipitation, growth, crystal wall transition, and crystal transition in organic solvents, regardless of the type of crystal form. The single-layer electrostatic electrophotographic photosensitive member comprising a charge generating transport layer formed by using a charge generating transport liquid formed by combining a specific hole transporting material and an electron transporting material in a suitable combination with the pigment is excellent in electrostatic characteristics and noise. The invention has been devised to provide a high quality image that is absent.

Hereinafter, the present invention will be described in more detail.

Phthalocyanine pigment used in the present invention is a metal-free phthalocyanine having a structure of the formula (1), the crystal form is not particularly limited, but the improvement of photosensitivity In consideration of the aspect, it is preferable to use the X-form crystal form, and it is possible to synthesize using a known production method:

In the above formula, R1 to R16 are each independently a hydrogen atom, a halogen atom, a nitro group, an alkyl group or an alkoxy group.

In addition, the perylene pigment used in the present invention has a structure of Formula 2:

In the above formula, R17 and R18 are each independently a methyl group, hydroxyethyl group, ethyl group, methoxyethyl group, propyl group, butyl group, pyridyl group, isopentyl group, pentyl group, hexyl group, isohexyl group, dichlorophenyl group, chlorophenyl group , Phenyl group, methylpyridyl group, cyclohexyl group, benzthiazole group, benzyl group, methoxyphenyl group, phenylethyl group or quinoline group.

When the metal-free phthalocyanine and the perylene pigment are used together as in the present invention, the metal-free phthalocyanine and the perylene pigment form a pn bond, thereby inhibiting the transition of the crystalline form of the metal-free phthalocyanine and increasing the charge generation efficiency to thereby increase the final photosensitive member. High sensitivity can be realized.

In the present invention, the metal-free phthalocyanine and perylene pigments are used in the form of mixed crystals or simple mixtures. Here, mixed crystal means that two or more kinds of compounds are incorporated at the molecular level in the primary particles of the crystal, and whether it is a simple mixture or mixed crystal of single compound crystals is X-ray diffractogram, infrared absorption spectrum or visible light absorption. It can easily identify by a well-known analysis method based on the difference of a physical property like a spectrum. Mixed crystals of metal-free phthalocyanine and perylene pigments can be produced, for example, in an acidic phase manner. The mixed crystal composition thus prepared may be used as a charge generating material as it is, but when a specific crystalline form is desired, it may be used after work-up by a known method. For example, it is possible to work up by chemical solvent treatment or by dry milling.

The content of the metal-free phthalocyanine pigment in the charge-generating transport coating solution of the present invention is 0.01 to 5% by weight, the content of perylene pigment is 0.0005 to 0.5% by weight, wherein the ratio of the metal-free phthalocyanine and perylene pigment is a metal-free phthalocyanine: Perylene

It is preferable that it is pigment = 99.5: 0.5-80: 20 (w / w). If the ratio of the perylene pigment is too low, there is no effect of crystal stabilization and charge generation enhancement, whereas if the ratio is too high, the photosensitivity decreases due to the characteristics of the perylene itself.

Meanwhile, in the present invention, a butadiene compound having high mobility and excellent compatibility with other components is used as the hole transport material, and a diphenoquinone compound of Formula 3 is used as the electron transport material:

In the above formula, R19 to R22 are each independently a methyl group, an ethyl group, an isopropyl group, or a t-butyl group.

The charge-generating transport coating solution of the present invention includes 2 to 10% by weight of butadiene-based hole transport material and 2 to 10% by weight of diphenoquinone-based electron transport material, wherein the ratio of diphenoquinone-based electron transport material and butadiene-based hole transport material is deferred Noquinone electron transport material: Butadiene hole transport material = It is preferable that it is 5: 95-90: 10 (w / w), More preferably, it is 20: 80-70: 30 (w / w). In the present invention, a combination of a butadiene-based hole transport material and a diphenoquinone-based electron transport material is important, and when the ratio of the diphenoquinone-based electron transport material is insufficient, light sensitivity decreases due to a decrease in electron transfer efficiency, whereas when the ratio is too high, holes Deterioration in light sensitivity occurs due to uneven movement.

On the other hand, the binder resin required for preparing the charge generating transport coating solution of the present invention is polyvinyl butyral, polyarylate (such as a condensation polymer of bisphenol A and phthalic acid), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic Resin, polyacrylamide resin, polyamide, polyvinyl pyridine, cellulose resin, urethane resin, epoxy resin, silicone resin, polystyrene, polyketone, polyvinyl chloride, vinyl chloride-vinyl acid copolymer, polyvinyl acetal, polyacryl Insulating resin such as ronitrile, phenol resin, melamine resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, or organic photoconductive polymer such as polyN-vinylcarbazole, polyvinyl anthracene, polyvinylpyrene, However, the present invention is not limited thereto, and most preferably, polycarbonate having excellent durability and wear resistance. Good.

The binder resin content of the charge generating transport coating solution of the present invention is 5 to 20% by weight, wherein the ratio of the charge transport material (hole transport material + electron transport material) and the binder resin is the charge transport material: binder resin = 20:80 to 60 It is preferable that it is: 40 (w / w). When the binder resin is insufficient, dispersion is difficult and dispersion stability is lowered. On the other hand, when the binder resin is used excessively, the dispersion stability of the pigment increases, but due to the deterioration in sensitivity due to the excessive binder resin, the desired effect cannot be expected.

The solvent of the coating liquid of the present invention depends on the type of resin selected and should be one that does not affect the adjacent layer during coating. Examples of preferred organic solvents include aromatic hydrocarbons such as benzene, xylene, ligroin, monochlorobenzene and dichlorobenzene; Ketones such as acetone, methyl ethyl ketone and cyclohexanone; Alcohols such as methanol, ethanol and isopropanol; Esters such as ethyl acetate and methyl cellosolve; Aliphatic halogenated hydrocarbons such as carbon tetrachloride, chloroform, dichloromethane, dichloroethane and trichloroethylene; Ethers such as tetrahydrofuran, dioxane, dioxolane and ethylene glycol monomethyl ether; Amides such as N, N-dimethyl formamide and N, N-dimethyl acetamide; And sulfoxides such as dimethyl sulfoxide, and one or two or more thereof may be mixed and used.

The organic solvent content of the coating liquid of the present invention is 60 to 90% by weight.

The coating solution of the present invention may further contain an electron-accepting substance for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue upon repeated use in addition to the above-described charge generating material, hole transporting material and electron transporting material. As such an electron-accepting substance, succinic anhydride, maleic anhydride, dibromic succinic anhydride, phthalic anhydride, 3-nitro phthalic anhydride, 4-nitro phthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, trimellitic anhydride Compounds with high electron affinity such as triacid, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetratoranoquinodimethane, chloranyl, bromanyl, o-nitro benzoic acid, and ｐ-nitro benzoic acid Can be used. It is preferable that the addition ratio of an electron accepting material is 0.001-5 weight part with respect to 1 weight part of charge transport materials.

In addition, the coating liquid of the present invention may contain a deterioration inhibitor such as an antioxidant and a light stabilizer for the purpose of improving the environmental resistance and stability to harmful light. Examples of compounds that can be used for such purposes include chromatinol derivatives such as tocopherol and etherified or esterified compounds thereof, polyaryl alkane compounds, hydroquinone derivatives and their mono- or dietherated compounds, benzophenone derivatives, benzotria Sol derivatives, thioether compounds, phenylenediamine derivatives, phosphonic acid esters, phosphorous acid esters, phenol compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, hindered amine compounds and the like.

As a dispersing device for dispersing the above components to produce the coating liquid of the present invention, a device commonly used in the field of paints and inks is used. For example, an Ato lighter, a ball mill, a sand mill, a high speed mixer, a vanvari mixer ， Special mixer, roll mill, three roll mill, nano-mizer, microfluidizer, stamp mill, planetary mill, vibration mill, kneader, etc. can be used, if necessary, glass beads, steel beads, zirconia oxide beads, etc. Alumina balls, zirconia balls, flint stones, etc. may be used.

The coating solution of the present invention prepared as described above is coated on a conductive substrate and dried to form a charge generating transport layer.

In coating, conventional coating apparatuses such as dip coater, spray coater, wire bar coater, applicator, doctor blade, roller coater, curtain coater, bead coater and the like can be used.

The material of the conductive substrate is not particularly limited as long as it is a conductive material, and sheet shape, cylindrical shape, and the like are also possible, and the shape thereof is not particularly limited. Thus, for example, a metal drum made of aluminum, vanadium, nickel, copper, zinc, palladium, indium, tin, platinum, stainless steel, chromium, or pearl, or a conductive material prepared by dispersing a conductive material in conductive plastic or plastic It is possible to use a plastic drum made of plastic, or a metal sheet or a plastic sheet in which metal is deposited or laminated on the surface as a substrate.

In addition, such a conductive substrate may be provided with a layer, referred to as a blocking layer or under coated layer, on the surface, for the purpose of preventing charge injection from the substrate or improving adhesion. Formation of such a blocking layer or undercoat layer includes polyamides such as nylon 6, nylon 66, nylon 11, nylon 610, copolymerized nylon and alkoxy methylated nylon; Film-forming polymer resins such as casein, polyvinyl alcohol, ethylene-acrylic acid copolymer, gelatin, polyvinyl butyral; Metal oxides such as zinc oxide, titanium oxide and aluminum oxide; Or resin which disperse | distributed electroconductive, semiconductive, or dielectric particles, such as silicon nitride, a silicon carbide, carbon black, is used.

The thickness of the charge generating transport layer formed according to the present invention is 5 to 50 µm, preferably 15 to 40 µm.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example 1

0.13 parts by weight of X-type metal-free phthalocyanine

0.01 parts by weight of 2,9-dimethylanthra [2,1,9-def: 6,5,10-d'e'f '] diisoquinoline-1,3,8,10-tetrone, with a hole transport material 5.1 parts by weight of 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene, 3,5-dimethyl- 3 ', 5'-di-ｔ as an electron transport material 90 parts by weight of tetrahydrofuran and toluene, 3.1 parts by weight of -butyl 4,4'-diphenoquinone, 10.1 parts by weight of polycarbonate resin (TS-2040: Teijin Co., Ltd.), and 0.05 parts by weight of antioxidant Irganox 565 (Shibagai Co., Ltd.) After dissolving in 5 parts by weight of a mixed solvent, 800 parts by weight of zirconia beads were added and dispersed for 72 hours using a ball mill.

The beads obtained above were filtered using a filter, coated on aluminite-treated aluminum drums using a dip coating method, and then dried in a 120 degree oven for 30 minutes to achieve a film thickness of 20 μm. The electrical sensitivity of this photosensitive drum was measured with an electrostatic characteristic measuring instrument (PDT-2000: QEA Co., Ltd.) whose light source was adjusted to 780 nm to evaluate the light sensitivity. The results are as described in Table 1 below.

Example 2

Bis (para-4,4-diphenyl-) instead of 5.1 parts by weight of 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene as a hole transporting material in the preparation of the dispersion It is the same as that of Example 1 except having used 5.1 weight part of 1, 3- butadiene phenyl) phenylamines.

Example 3

Bis (para-4,4-di (para) instead of 5.1 parts by weight of 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene as a hole transporting material in the preparation of the dispersion It is the same as that of Example 1 except having used 5.1 weight part of -methylphenyl) -1,3-butadienephenyl) -para-methoxyphenylamine.

Comparative Example 1

N, N'-bis- (3-methylphenyl instead of 5.1 parts by weight of 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene as a hole transporting material in the preparation of the dispersion It is the same as that of Example 1 except having used 5.1 weight part of -N, N'-bis (phenyl) benzidine.

Comparative Example 2

N, N, N ', N'-tetra instead of 5.1 parts by weight of 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene as a hole transporting material in the preparation of the dispersion The same procedure as in Example 1 was carried out except that 5.1 parts by weight of kiss (3-methylphenyl) benzidine was used.

Comparative Example 3

0.13 parts by weight of X-type metal-free phthalocyanine as the charge generating material, 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene as the hole transport material, 8.2 parts by weight of polycarbonate After dissolving 10.1 parts by weight of the resin (TS-2040: Deijin Co.) and 0.05 parts by weight of the antioxidant Iganox 565 (Shibagai Co.) in 90 parts by weight of tetrahydrofuran and 5 parts by weight of toluene, 800 parts by weight of zirconia beads were added. And dispersed for 72 hours using a ball mill.

The beads obtained above were filtered using a filter, coated on aluminite-treated aluminum drums using a dip coating method, and then dried in a 120 degree oven for 30 minutes to achieve a film thickness of 20 μm. The electrical characteristics of this photosensitive drum were measured with an electrostatic characteristic measuring instrument (PDT-2000: QEA Co., Ltd.) whose light source was adjusted to 780 nm, and the light sensitivity was evaluated. The results are as described in Table 1 below.

Comparative Example 4

0.13 parts by weight of X-type metal-free phthalocyanine and 2,9-dimethylanthra [2,1,9-def: 6,5,10-d'e'f '] diisoquinoline-1, It is the same as that of the said comparative example 3 except having used 0.007 weight part of 3,8,10- tetratrons.

Comparative Example 5

It was the same as that of Example 1 except having used 8.2 weight part of electron transport materials 3, 5- dimethyl- 3 ', 5'- di-tet- butyl 4, and 4'- diphenoquinone instead of a hole transport material.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Vr 34 30 22 36 40 48 82 40 E1 / 2 0.32 0.28 0.25 0.35 0.38 0.40 0.82 0.68 E100 2.23 1.85 1.20 1.95 2.14 3.30 3.24 2.78 DD5 89 89 90 84 88 88 87 82

Vr (V): Surface potential 10 seconds after exposure

    E1 / 2 (μJ / cm 2): exposure energy when it becomes 1/2 of surface potential immediately before exposure

    E100 (μJ / cm 2): exposure energy when the surface potential immediately before exposure is -100

    DD5 (%): surface potential retention after 5 seconds of exposure in the dark room

As described in detail above, the charge generation transport coating solution of the present invention has excellent compatibility between components and no change over time even in long-term use, and the single-layer positive electrostatic photosensitive member including the charge generation transport layer formed therefrom has excellent sensitivity. Image quality has an advantage.

Claims (7)

In the charge-generating transport coating solution containing a X-type metal-free phthalocyanine of the formula (1), a perylene pigment of the formula (2), a butadiene-based hole transport material, a diphenoquinone-based electron transport material, a binder resin and an organic solvent, a diphenoquinone-based electron Charge-generating transport coating liquid, characterized in that the ratio of the transport material and butadiene-based hole transport material is 5:95 ~ 90:10 (w / w). [Formula 1] In the above formula, R1 to R16 are each independently a hydrogen atom, a halogen atom, a nitro group, an alkyl group or an alkoxy group; [Formula 2] In the above formula, R17 and R18 are each independently a methyl group, hydroxyethyl group, ethyl group, methoxyethyl group, propyl group, butyl group, pyridyl group, isopentyl group, pentyl group, hexyl group, isohexyl group, dichlorophenyl group, chlorophenyl group , Phenyl group, methylpyridyl group, cyclohexyl group, benzthiazole group, benzyl group, methoxyphenyl group, phenylethyl group or quinoline group. The method of claim 1, 0.01-5 wt% of the X-type metal-free phthalocyanine; 0.0005 to 0.5% by weight of the perylene pigment; 2 to 10% by weight of the butadiene-based hole transport material; 2 to 10% by weight of the diphenoquinone-based electron transport material; 5 to 20% by weight of the binder resin; And 60 to 90% by weight of the organic solvent Coating liquid, characterized in that it comprises a. The coating liquid according to claim 1 or 2, wherein the ratio of the metal-free phthalocyanine to the perylene pigment is 99.5: 0.5 to 80:20 (w / w). delete The coating liquid according to claim 1 or 2, wherein the ratio of the charge transport material (hole transport material + electron transport material) to the binder resin is 20:80 to 60:40 (w / w). The coating liquid according to claim 1 or 2, wherein the diphenoquinone-based electron transport material has a structure of Formula 3 below: [Formula 3] In the above formula, R19 to R22 are each independently a methyl group, an ethyl group, an isopropyl group, or a t-butyl group. A single layer positive electrostatic photosensitive member comprising a charge generating transport layer formed using the charge generating transport coating solution of claim 1.