KR940001485B1 - Electrophoto-sensitive materials and making method thereof - Google Patents

Abstract

The photosensitive material for organic stack electrophotography is disclosed in which a hydrazones electron hole injecting efficient layer is formed between a charge generator layer and charger carrier layer.

Description

Organic laminated electrophotographic photosensitive member and manufacturing method thereof

The present invention relates to an organic laminated electrophotographic photoconductor, and more particularly, to an organic laminated electrophotographic recording medium comprising a conductive support, a charge generating layer, a hole injection efficiency layer and a charge transport layer, which can be used as an electrode, and a manufacturing method thereof. It is about.

Currently, the photosensitive member of the recording medium for an electronic copying machine used in the radiation process mainly uses an inorganic material of selenium (Se), amorphous silicon (ZnO) or zinc oxide (ZnO). Although the sensitivity and durability are excellent, the wavelength band of the sensitive light is limited, and it is relatively expensive in terms of price, and because the inorganic material must be coated on the drum by vacuum deposition method, the coating was relatively difficult. There was also difficulty in controlling the mechanical properties.

Therefore, in recent years, a multilayer photoconductor is widely used, and a layered electrophotographic photoconductor is a wide band (visible light region) by using various types of photoconductive materials instead of inorganic materials as components of an electrophotographic recording medium. It has enabled the wavelength sensitivity of, and makes the photoreceptor cheap and easy to manufacture.

That is, it was possible to simply manufacture by using a simple spin coating or dip coating using the excellent coating properties that can be obtained in the organic material system rather than the vacuum deposition method used in the inorganic material system, Furthermore, the mechanical properties of the drums could be controlled by using suitable polymers or, if necessary, polymer mixtures.

Accordingly, in the present invention, in the organic laminated electrophotographic photoconductor composed of a conductive support and a charge generating layer and a charge transport layer, which can be used as an electrode, in particular, by forming a hole injection efficiency layer between the charge generating layer and the transport layer, It is an object of the present invention to provide a novel organic-layer electrophotographic photosensitive member that improves the efficiency of the organophotoreceptor and improves the sensitivity, residual potential and initial potential of the organophotoreceptor.

Hereinafter, the present invention will be described in detail.

The present invention relates to an organic laminated electrophotographic photosensitive member having a conductive support that can be used as an electrode, a charge generating layer and a charge transporting layer, wherein a hydrazone-based compound component represented by the following general formula (I) is formed between the charge generating layer and the charge transporting layer: A hole injection efficiency layer is formed.

Wherein R represents any one group selected from the following general formulas (I-a), (I-b) and (I-c).

In order to manufacture the photoconductor according to the present invention, in the manufacture of an organic laminate electrophotographic photosensitive member having a conductive support that can be used as an electrode, a charge generating layer and a charge transport layer, 35 to 60 wt% of the selected charge generating material, 36 to 54 wt% of the binder resin and 2 to 11 wt% of the hydrazone sensitizer are mixed and dispersed in a solvent of 10 to 20 times the weight of the charge generating material, and the charge generating layer is placed on the conductive support. Coating and forming a hole injection efficiency layer on the charge generating layer by mixing and dispersing the hydrazone compound represented by the general formula (I) in a solvent having a weight of 10 to 20 times. 40 to 60 wt% of the hydrazone compound and oxadiazole compound used in the efficiency layer and 40 to 60 wt% of the binder resin were Were mixed in a solvent of between 10 to 20 times the weight of the binder resin is prepared by coating a charge transport layer formed.

Referring to the present invention in more detail as follows.

The present invention is to produce an organic laminated electrophotographic photosensitive member having a conductive support and a charge generating layer and a charge transport layer that can be used as an electrode, by forming a hole injection efficiency layer between the charge generating layer and the charge transport layer to improve charge transport efficiency It is characterized by the remarkable improvement. For the preparation thereof, the charge generating material selected from symmetric quinone compound, perylene compound and symmetric azo compound is 35 to 60wt%, binder resin 36 to 54wt%, hydrazone The second to llwt% is mixed and dispersed in a suitable solvent in an amount of 10 to 20 times the weight of the charge generating material and formed on the conductive support.

In this case, when the charge generating material is relatively larger than the binder resin, the sensitivity may be improved, but the mechanical properties are deteriorated. On the contrary, when the charge generating material is relatively small, the sensitivity and the general properties are deteriorated.

Here, a compound that can be used as a charge transport layer is separated into two layers, and the hydrazone-based compound of Formula (I), which is a charge transport material, is mixed and dispersed in a suitable solvent having a weight of 10 to 20 times to form a hole injection efficiency layer. On the other hand, a compound selected from the hydrazone-based and oxadiazole-based compounds which are used in the hole injection efficiency layer as the charge transport layer is 40-60wt% by weight ratio and 40-60wt% of the binder resin by 10-20 to the weight of the binder resin. The charge transport layer is formed by mixing and dispersing in a suitable solvent twice, to form a stack of electrophotographic photosensitive members.

The conductive support in the present invention may be used as a conventional one that can be used as an electrode, for example, having a thickness of about 0.5μm and irregularities of less than 0.01μm to use polyethylene terephthalate (PET) deposited aluminum There is a number.

In addition, in order to form the charge generating layer, it is necessary to use a material of a certain composition capable of generating charges when irradiated with light. The charge generating material is represented by the following general formulas (II-a) to (II-h). It is selected from pigment materials of symmetric dicyclic quinone and perylene compounds and symmetric azo compounds, and the hydrazine zone compound of the general formula (I) is used as a sensitizer in the form of die. The solvent as the dispersion medium is selected from tetrahydrofuran, isopropyl alcohol, 1,2-dichloroethane and 1,4-dioxane.

In addition, polyvinyl butyral, polyester, etc. are used as a binder resin for forming a layer and maintaining mechanical strength with a matrix of charge generating materials.

In the case where the charge generating layer is formed of such a material, it is preferable to form such that the thickness after drying is 0.01 to 10 m, preferably 0.05 to 5 m.

If the thickness is too thin, the absolute amount of generated charges is insufficient, and if too thick, positive and negative ions are generated simultaneously by light, so traps by negative ions occur during cation (hole) transfer.

Meanwhile, in the present invention, the hole injection efficiency layer is formed on the charge generating layer together with the charge transport layer. The hole injection efficiency layer uses a hydrazone-based compound, and the solvent used as the dispersion medium is 1,2-dichloro. Select one of ethane, methylene chloride, methyl ethyl ketone, and isopropyl alcohol, and disperse the hydrazone compound in the form of a die in an amount of 10 to 20 times by weight to coat the charge transport layer to form a hole injection efficiency layer. Let's do it.

At this time, the thickness of the layer is preferably formed so as to be 0.05 to 1 m in thickness after drying.

Thereafter, a charge transport layer is formed on the hole injection efficiency layer, and as a composition, one selected from the general formulas (I) and the following general formulas (III-a) to (III-d) may be used. The solvent used as the dispersion medium is one selected from 1,2-dichloroethane, methylene chloride, methyl ethyl ketone and isopropyl alcohol, and a binder resin such as polycarbonate, polyvinyl formal and polyester used as a matrix of the charge transport material. To form a charge transport layer.

2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole

2- (4-biphenylyl) -5-phenyl-1,3,4-oxadiazole

2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole

1,4-bis (5-phenyloxazol-2-yl) benzene

Herein, the thickness after drying of the layer is preferably 10 to 40 µm, preferably 15 to 20 µm, in consideration of the limitation of the length of the charge transporting, to prepare an organic electrophotographic photosensitive member.

Meanwhile, according to the present invention, the sensitizers of the hole injection efficiency layer and the charge generating layer use the same hydrazone-based compound, and the effect thereof is the same in terms of reducing the energy gap, but in terms of efficiency. There is a big difference.

In other words, the irradiated light energy surpasses the band gap in the charge generating layer to generate charge, and in the charge transport layer, the energy of the excited state in the double bond and symmetric resonance structure of the transport material is generated. Supply it.

At this time, the main role of the hole injection efficiency layer is to reduce the energy gap between the generated charge and the excited state uniformly, and the sensitizer prevents the loss of charge generated by trapping inside the charge generating layer. The main action is to make the efficient transfer of charges.

In the electrophotographic recording medium manufactured as described above, that is, an electrophotographic copying process using a photoreceptor, air is ionized by corona discharge (-5KV to -7KV), and darkness is formed on the surface of the organic layered photoconductor (OLP). Dislocations are formed across the OLP in the stomach.

Irradiation of light onto the OLP to form an electrical latent image to be radiated next generates electron-hole pairs in the charge generating layer, where efficient energy transfer is performed for holes in the ion pairs generated by the hole injection efficiency layer. And uniform hole transfer occurs, and vice versa.

Therefore, in the charge transport layer, electrons are neutralized by transferring holes to the anion layer formed on the surface of the OLP, and as a result, an electric latent image formed of negative ions is formed in the portion where the holes are not transferred.

In addition, the negatively charged electric latent image is developed on the opposite positively charged toner, and undergoes a process in which the latent image is printed again on the paper charged by the corona discharge.

At this time, since all the toner is not transferred to the paper, it is removed once by irradiation of light, and finally by mechanical or electrostatic brushing. In addition, toner printed on paper is fixed by pressure or heat to complete copying.

As described above, according to the present invention, the general formulas (II-a) to (II-) among polycyclic quinone-based, perylene-based and azo-based compounds are improved by improving sensitivity and residual potential, which are the biggest problems of the organic multilayer photoconductive drum system. By using a symmetrical material, which is a compound of h), and a material having an electron cloud and a non-covalent electron pair, the material capable of mutual attraction between these molecules can increase the charge generation yield by delocalizing charges during charge generation. .

In addition, the charge-transporting material used is a hydrazone-based material. Since the nitrogen of the hydrazone-type has a non-covalent electron pair, the molecules form hydrogen bonds (CHN --- HNC) in which nitrogen is involved. The attraction force can act, and since there is a phenyl group on both sides of the nitrogen, the resonance structure of the following form is possible, so that the function can be increased.

In the hole transport injection efficiency layer unique to the present invention, the hydrazone-based compound forms a direct layer without the use of a binder resin, thereby shortening the transport distance between charge transport materials and increasing transport energy efficiency.

In other words, the problem of mechanical strength caused by the absence of binder resin is that the hole injection efficiency layer between the charge transport layer and the charge generating layer can replace the mechanical strength of the binder resin. It can play a big role in improving.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by Examples.

Example 1

As the conductive support, a polyester film (manufactured by SKC Co., Ltd.) deposited with aluminum was used. As the charge generating layer material, 1.8 g of the material represented by the general formula (II-c) and the general formula (Ic) as the sensitizer were used. 0.2 g of the above-mentioned substance of formula (I) having a group of) was used, and 60 g of tetrahydrofuran (Aldrich) was used as a solvent, and 2 g of polyethylene terephthalate (PET: SKC-100) was used as a binder resin. Using a spin coater (Integrated Tech Co., Ltd.), after drying for 30 minutes at room temperature, convection drying for 1 hour at 64 ℃ was coated to a thickness of 1μm.

The hole injection efficiency layer is mixed with 2 g of the charge transport material of Formula (I) having the group of Formula (Ic) and 200 g of methylene chloride (Aldrich) as a solvent, using a spin coater (Integral Tech) After coating for 30 minutes at room temperature drying, 60 ℃ convection drying for 1 hour and then coated to a thickness of about 0.5μm.

In addition, as the charge transport layer, 2 g of the charge transport material of the general formula (I) having the group of the general formula (Ic), 30 g of methylene chloride (Aldrich) as the solvent, and 2 g of polycarbonate (Laxan) as the binder resin After the composition was formed to form a coating and dried for 30 minutes at room temperature, and conducting convection drying at 60 ℃ 1 hour was coated on the hole injection layer with a spin rotor (Integral Tech) to the thickness of about 20μm.

The charging characteristics were measured using an electrostatic charging test apparatus (EPA-8100; Kawaguchi, Japan), and the results are shown in Table 1 below.

(Measuring conditions)

STATIC MODE # 3, 20Ø Sample

Preliminary light exposure: 2,000 lux, 2.0 seconds

DC potential: -5kv, 5.0 seconds

Dark Decay: 5.0 seconds

Suspension: 5.0 seconds

Light exposure: 5.0Lux, 10 seconds

Comparative Example 1

Example 1 was carried out in the same manner, but the charge generating layer was composed of the compound of the general formula (II-c) of the charge generating material 2g, the solvent of tetrahydrofuran 60g, the binder resin was composed of PET 2g, As the charge transport layer, 2 g of an oxazole-based charge transport material (2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole) having the following structural formula

30 g of methylene chloride as a solvent and 2 g of polycarbonate as a binder resin were prepared, and the same procedure as in Example 1 was carried out to produce the same conditions.

Comparative Example 2

The same method as in Example 1, was prepared and measured under the same conditions, except that only the hole injection efficiency layer to form an organic layer.

TABLE 1

As can be seen from Table 1, in Comparative Example 2 compared with Comparative Example 1, the sensitivity of the drum was improved by about 4 (Lux · Sec).

In addition, the initial potential potential and the residual potential is maintained as a correlation, the residual potential of Comparative Example 2 was shown to be inferior to that of Comparative Example 1, but the initial potential potential showed a relatively improved results. This result is due to the addition of a sensitizer to the charge generating layer in Comparative Example 2.

On the other hand, in Example 1 according to the method of the present invention by adding a hole injection efficiency layer to the sensitizer, it was possible to improve the about 600V and decrease the residual potential of the early charging mice than in Comparative Example 2.

Claims (6)

In an organic laminated electrophotographic photosensitive member having a conductive support that can be used as an electrode, a charge generating layer, and a charge transport layer, a hole injection efficiency of a hydrazone-based compound component represented by the following general formula (I) between the charge generating layer and the charge transport layer: An organic layer electrophotographic photosensitive member, characterized in that a layer is formed.

In the formula, R represents any one group selected from the following general formulas (I-a), (I-b) and (I-c).

35-60wt% of charge generating materials selected from symmetrical polycyclic quinone compounds, perylene compounds and symmetrical azo compounds in the manufacture of an organically charged electrophotographic photosensitive member having a conductive support that can be used as an electrode, a charge generating layer, and a charge transport layer; , Binder resin 36 ~ 54wt% and hydrazone sensitizer 2 ~ 11wt% by mixing and dispersing in a solvent of 10 to 20 times the weight of the charge generating material to form a charge generating layer on the conductive support, the following general formula (I Hydrazone-based compound and oxadiazole-based compound used in the hole-injection layer were formed by coating and dispersing the hydrazone-based compound represented by) in a solvent having a weight of 10 to 20 times. 40 to 60 wt% of the selected one and 40 to 60 wt% of the binder resin are mixed with a solvent of 10 to 20 times the weight of the binder resin. Organic layer manufacturing method of the electrophotographic photosensitive member and a transport layer characterized by forming the coating.

In the formula, R represents any one group selected from the following general formulas (I-a), (I-b) and (I-c).

The symmetric polycyclic quinone compound, the perylene-based compound, and the symmetrical azo-based compound of the components constituting the charge generating layer are selected from compounds represented by the following general formulas (II-a) to (II-h). Method for producing an organic laminated electrophotographic photosensitive member characterized in that.

The method of claim 2, wherein the oxadiazole-based compound of the components constituting the charge transport layer is prepared using a compound selected from compounds represented by the following general formula (II-a) to II-d) of the organic laminated electrophotographic photosensitive member Way.

3. The method for manufacturing an organic layer electrophotographic photosensitive member according to claim 2, wherein the hole injection efficiency layer is formed so as to have a thickness of 0.05 to 0.1 m after drying thereof. The method according to claim 2, wherein the charge generating layer and the charge transport layer are formed so as to have a thickness of 0.1 to 10 m and 10 to 40 m, respectively, after drying.