JPS6231861A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body superior in fatigue resistance by incorporating a halogen-containing solvent in photosensitive layers formed on a conductive substrate. CONSTITUTION:The photosensitive body is composed of the conductive substrate 1, an electrostatic charge generating layer 2, and a charge transfer layer 3, and interlayers may be formed between each adjacent couple of these layers, and a surface protective layer may be formed on the uppermost layer. The halogen-containing solvent and, when needed, containing an optional solvent, are incorporated at the time of forming the photosensitive layers 2, 3, and this halogen-containing solvent has a low boiling point of 30-180 deg.C, preferably, 35-150 deg.C, such as dichloromethane, 1,1-dichloroethane, 1,2-dichloroethane, or chloroform, and it is used alone or in a combination of some of them, in an amount of 0.05-10wt%, preferably, 0.2-10wt% of the total weight of the photosensitive layers 2, 3, thus permitting the obtained photosensitive body to be enhanced in resistance to fatigue.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoconductor suitable for use in electrophotography, and more particularly to a photoconductor that exhibits little variation in charge retention and sensitivity during repeated use.

Prior Art] Conventionally, photosensitive layers used in electrophotographic photoreceptors include Se,
Inorganic photoconductive materials such as GdS and ZnO are widely used. However, due to various demands such as the fact that some materials themselves have Ui properties and the need to avoid environmental pollution,
In recent years, research using organic photoconductive substances instead of inorganic photoconductive substances has been actively conducted (for example,
! +50-1 (see Publication No. 1498, etc.), compared to inorganic photoconductive materials, such organic photoconductive materials have a higher fi! Although there are advantages such as the optical layer is highly flexible, easy to manufacture, and a photoreceptor with stable electrophotographic characteristics can be obtained at a lower cost, the sensitivity and durability are not necessarily satisfactory.

As a solution to this drawback, there is a so-called functional molecule a type photoreceptor in which the charge generation function and the charge transport function are individually assigned to different substances in the photosensitive layer. This mechanical separation type photoreceptor has a charge generation layer and a charge transport layer coated on a conductive substrate in order, and most of the incident light is absorbed by the charge generation layer to generate carriers. A photoreceptor that has the function of injecting charges into a charge transport layer without being deactivated by recombination or capture, and has been put into practical use due to its high sensitivity and durability.

As charge-generating substances that are effective for such functionally separated type photoreceptors, a number of substances have been proposed, including (1) black metal substances, and (2) organic dyes and organic pigments.

As an example of using the former inorganic substance,
No. 198 discloses a combination of amorphous selenium and an organic charge transport material. Examples of the latter include JP-A-47-37543, JP-A-55-22834, and JP-A-54-
No. 79832 and No. 58-116040 disclose examples in which a bisazo compound is used as a charge generating substance.

However, although these at@ separation type organic photoreceptors have mechanical durability, the current situation is that they cannot be said to be free from problems in their electrical durability.

'In the Shigeko photographic process, the charge retention in the dark and the degree of charge attenuation during exposure are considered to be indicators of the performance of the photoreceptor. By repeating the process, that is, by performing multiple printouts, the charge retention ability of the photoreceptor may decrease, and the degree of charge attenuation during exposure, that is, the sensitivity, often changes at the same time. In such a case, there is a problem in that the contrast between exposed and non-exposed areas varies, making it impossible to obtain a good image.

Various attempts have been made to improve the fatigue characteristics of such organophotoreceptors. For example, in the case of a functionally separated type, there are methods of changing the combination of a charge generating substance and a charge transporting substance, or methods of changing the combination of a charge generating substance and a charge transporting substance, or Japanese Patent Application Laid-Open No. 49-34327, No. 58- 5434fli issue, episode 5
As disclosed in Japanese Patent Application No. 8-40555, attempts have been made to improve fatigue properties by adding various additives to photoreceptors. However, in the former case, fatigue properties can be improved by changing the combination, but on the other hand, sensitivity may be reduced to some extent, and in the latter case, of course, excessive exfoliation can occur if the amount of additives added is too small. If added, there is a problem that phenomena such as bleed-out occur and control is not necessarily easy.

[Problems to be Solved by the Invention] Therefore, the present invention solves the above-mentioned drawbacks of the prior art, and provides a solution with less variation in charge retention and sensitivity during repeated use.
That is, the technical problem is to provide a photoreceptor with excellent fatigue resistance.

[Means for Solving the Problems] As a result of extensive research to solve the above problems, the inventors of the present invention have found that a halogen-containing solvent remains in the photosensitive layer, and that the remaining amount of the solvent can be reduced by adjusting the drying conditions. It was discovered that M control can be easily performed, leading to the present invention.

That is, the photoreceptor according to the present invention is a photoreceptor in which at least a photosensitive layer is formed on a conductive substrate, and the photoreceptor contains a halogen-containing solvent (hereinafter referred to as the halogen-containing solvent of the present invention). It is characterized by

The present invention will be explained in detail below.

The photoreceptor of the present invention has a photosensitive layer on a conductive substrate. Preferred embodiments of the layer structure of the photoreceptor of the present invention include the following layer structures (1) to (8).

(1) As shown in FIG. 1, from the upper layer, the charge transport layer 3,
A charge generation layer 2 and a conductive substrate 1 are constructed in this order.

(2) As shown in FIG. 2, in the layer structure shown in (1) above, an undercoat layer 4 (
(layers with functions such as intermediate layer, adhesive layer, etc.)

(3) As shown in FIG. 3, from the upper layer, the charge generation layer 2.
'Jl charge transport layer 3, which is constructed at the top of the conductive substrate 1.

(4) As shown in FIG. 4, in the layer structure shown in (3) above, an undercoat layer 4 (
(layers with good functions such as intermediate layers, adhesive layers, etc.)

(5) As shown in FIG. 5, from the upper layer, a charge generation layer 2A containing a charge generation substance and a charge transport substance, a charge transport layer 3
, conductive substrate 1 in this order.

(6) As shown in FIG. 6, in the layer structure shown in (5) above, an undercoat layer 4 (
Those with functional layers such as intermediate layers and adhesive layers.

(7) As shown in FIG. 7, only a photosensitive layer 5 in which a charge generating substance or a charge generating substance and a charge transport substance are uniformly dispersed or dissolved is formed on a conductive substrate 1F.

(8) As shown in FIG. 8, in the layer structure shown in (7) above, a subbing layer 4 (a layer having functions such as an intermediate layer and an adhesive layer) is provided between the photosensitive layer 5 and the conductive substrate 1. What you have.

Further, in the above layer structure, an intermediate layer may be provided between each layer, and a surface protective layer may be formed as the uppermost layer.

In the present invention, the photosensitive layer refers to the layer structure of the photoreceptor described in (7) above.
, (8), it means the photosensitive layer, and in the case of a photoreceptor having a charge generation layer and a charge transport layer, it means the charge generation layer and the charge transport layer. .

In the present invention, the method for containing a halogen-containing solvent in the photosensitive layer is as follows: (1) A halogen-containing solvent (which may contain other known solvents as necessary) is used during the preparation of the photosensitive layer, and the halogen-containing solvent is not contained as a residual component even after drying. If the photosensitive layer does not contain a halogen-containing solvent when creating the photosensitive layer, use a method such as a spray method or a steam bath for the photosensitive layer after one production (either before or after drying is fine). If the residual component is added later as a residual component in the final photoconductor, (1) After the residual component becomes O after drying in 1 above, it is added later as in (2) and included in the final photoconductor as a residual component. There are various methods, such as when including.

By containing the halogen-containing solvent of the present invention in the photosensitive layer as described above, it is possible to improve the fatigue resistance of the photoreceptor. The halogen-containing solvent is preferably contained in the photosensitive layer, and when the photosensitive layer has the above-mentioned layer structure, it is contained in the charge generation layer, the charge transport layer, and either the charge generation layer or the charge transport layer. May contain.

In the present invention, what is the residual amount of halogen-containing solvent?

After extracting the remaining solvent, it can be quantified using gas chromatography. Specifically, a certain amount of the photoreceptor is accurately weighed, immersed in a ketone solvent such as acetone or methyl ethyl ketone, an ether solvent such as tetrahydrofuran, an alcohol solvent such as methanol or ethanol, and subjected to ultrasonic waves, etc. Extract the remaining solvent using

Next, benzene, toluene, xylene, hexane, etc. (these may be used selectively as necessary) are added as internal standard substances, and gas chromatography (HP-5974
Model: Huuret Paracard, Detector: FID)
Quantification may be performed using the internal standard method.

The halogen-containing solvent of the present invention refers to a halogen-containing low-boiling compound having a boiling point in the range of 30 to 180°C, preferably 35 to 150°C. Examples of the halogen-containing solvent of the present invention include dichloromethane, 1. 1-dichloroethane, l, 2
-dichloroethane, chloroform, carbon tetrachloride 1,1
．． 14-lichloroethane, 1.1.2-)dichloroethane, 1,1,2.2-tetrachloroethane.

Examples include 1.1,1.2-tetrachloroethane, and these may be contained alone or in combination with the two inserts E.

The content of the halogen-containing solvent of the present invention is 0.05 to 10% by weight, preferably 0.1 to 5% by weight based on the total weight of the photosensitive layer.
, more preferably a range of 0.2 to 1.0% by volume.

In order to significantly obtain the effects of the present invention, the amount is preferably 0.05% by weight or more, and on the other hand, from the viewpoints of preventing the occurrence of toner vent, preventing the residual potential from increasing, and repeated use. The amount is preferably 10% by weight or less in order to keep the fluctuation difference in the surface potential of the photoreceptor to a small level.

This content can be controlled by the drying conditions when producing the photoreceptor. Appropriate drying conditions can be determined by quantifying the residual amount that can improve the fatigue properties most by the method described below.

In the present invention, the conductive substrate is aluminum.

Fully bendable materials such as brass and stainless steel are molded into drum shapes or used as sheet-like films or foils, and polymeric materials such as polyethylene terephthalate, nylon, polyarylate, polyimide, polycarbonate, and insulating materials such as hard paper are used. It is used by molding a magnetic material into a drum shape or by applying a conductive treatment to a sheet-like film. Methods for conductive treatment include impregnation with a conductive substance, lamination of metal foil (for example, aluminum foil), vapor deposition of metal (for example, aluminum, indium, tin oxide, yttrium, etc.), and processing for conductivity.

Materials that can be used for the undercoat layer include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, vinyl nide resin, vinylidene chloride resin,
Styrene resin, vinyl acetate resin, styrene-butadiene combination, amount! ! vinyl chloride/-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-
Vinyl acetate-maleic anhydride copolymer, silicone resin,
Silicone-alkyd phase opening, phenol-formaldehyde resin, styrene-flukyd resin, poly-N-vinylcarhesol, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl alcohol resin, epoxy resin, urethane resin.

Polymer materials such as phenol resin and melamine resin, celluloses such as ethyl cellulose and carbodimethyl cellulose, and metal oxides such as aluminum oxide, indium oxide, and titanium oxide are used, and each can be used alone or in combination of two or more. be able to.

The undercoat layer is formed to a predetermined thickness by dissolving the above-mentioned material in an appropriate solvent and coating the solution on the conductive substrate. As the solvent, tetrahydrofuran, 1,2-dichloroethane, dioxane, etc. are preferably used, and combinations of halogen solvents and alcohol solvents, halogen solvents and ketone solvents, aromatic solvents and alcohol solvents, etc. are preferably used. Further, the halogenated solvents of the present invention, which will be described later, can be used alone or in combination as described above. The coating method is preferably a dipping method, a spray method, an extrusion method, a slide hopper method, etc. when the conductive substrate is in the form of a drum, and a roll method, extrusion or slide hopper method when the conductive substrate is in the form of a sheet. A slide hopper method or the like is preferably employed. The thickness of the undercoat layer formed in this way is preferably in the range of 0.01 to lOg+s;
．． The range of 05 to 54 m is more preferable.

A photosensitive layer having at least a charge generation layer is formed on the F intermediate layer. It is preferable that the charge generation layer is formed by coating a charge generation substance alone or dispersed in a binder on a conductive substrate.

As the charge generating substance, JP-A-59-53850 (guaiazulene pigment), JP-A-59-24852, JP-A-47
-30330 (perylene pigment), No. 53-9538
No. 59-9537 (phthalocyanine pigment), No. 53-40531 (pyrylium pigment), No. 47-3
No. 0332 (ginacridone pigment), No. 47-3033
No. 1 C- (Ndigo pigment), No. 54-21343 (cyanine pigment), No. 58-194035, No. 58-1
No. 15447, 5B-723757゜59-723
No. 78 and No. 59-73820 (Azo Pigments) (Azo Pigments) Publication No. 78, Publication No. 59-73820 (Azo Pigments).

(G-1) O0 (G-2) OO ((]-3) Φ Φ To form the charge generation layer, a solvent (even if it contains the halogen-containing solvent of the present invention) is added to the binder and the charge generation substance. As a binder, a dispersion liquid may be obtained by adding a dispersion liquid (good) and dispersing it by a known dispersion means such as a sand mill, a ball mill, or an ultrasonic dispersion, and then applying it to the conductive substrate directly or via an undercoat layer. Polymer materials such as acrylic resin, methacrylic resin, polyester resin, polycarbonate resin, styrene resin, and polyvinyl alcohol resin are used.
? The mixing ratio of the binder with the charge generating material and the charge generating material is 0 to 500 parts, preferably 0 to 200 parts, per 100 parts of the charge generating material. Suitable solvents include, for example, acetone, methyl ethyl ketone, cyclohexane, benzene, toluene, xylene, tetrahydrofuran, dioxane, methanol, ethanol, impropatol, chloroform, dichloromethane, ! , 2-dichloroethane, and other conventionally known solvents can be used, and these can be used alone or in combination of two or more.

Further, the above-mentioned solvent may contain the halogen-containing solvent of the present invention described above.The charge transport layer is formed by combining the charge transport substance and the binder in a suitable solvent (which may contain the halogen-containing solvent of the present invention). It is melted and formed on the above-mentioned 'ITt charge-generated waste generation layer.

As charge transport materials, Japanese Patent Publication No. 34-5487 (triazole derivatives), Japanese Patent Publication No. 35-1125 (oxazole derivatives), Japanese Patent Publication No. 34-5488 (oxadiazole derivatives), Japanese Patent Publication No. 34-103H (pyrazoline derivatives), 3
No. 5-11215, No. 37-18098 (imidazole derivative), JP-A-52-128373, No. 54-1
No. 10837 (fluorenone derivative), No. 54-591
No. 42 (carbazole derivative), No. 58-134642
No. 58-65440, but the present invention is not limited thereto.

Below margin Specifically, primary compounds are mentioned.

As a binder, it has high compatibility with charge transport substances,
Furthermore, materials with high transparency and insulation properties are preferred, and all materials commonly used for photoreceptors can be used. For example, polyester resins, polyethylene resins, polyamide resins, polycarbonate resins, epoxy resins, polyvinyl butyral resins, and Methyl methacrylate resin or the like is used.

The content of the charge transport substance is 2 parts per 100 parts of the binder.
The amount is 5 to 200 parts, preferably 50 to 100 parts.

The charge generation layer and the charge transport layer can be coated by the same method as the undercoat layer described above, and the thickness of the charge generation layer is 0.01 to 1.
0 end is preferable, more preferably 0.05 to 2 JLm
The charge transport layer preferably has a density of 5 to 5 1, more preferably 10 to 30.

[Effects of the Invention] According to the present invention, it is possible to obtain a photoreceptor that exhibits less variation in charge retention and sensitivity during repeated use, that is, has excellent fatigue resistance.

[Example] Preferred examples of the present invention are shown below, but the present invention is not limited thereto.

Example l Polycarbonate resin (product name: Panlite L-12
50, manufactured by Ondai Kasei Co., Ltd.) 5g, charge generating substance (exemplary compound G-18) 10g, 1,2-dichloroethane 10
00m was pulverized and dispersed in a ball mill to obtain a dispersion.

The resulting dispersion was applied to an aluminum plate by dip coating and dried at 100°C for 10 minutes to give a film thickness of 0.
A charge generation layer of 2 square meters was formed. Furthermore, 150 g of polycarbonate resin (trade name: Banrai 1-K-1300, manufactured by Ondai Kasei Co., Ltd.), charge transport material (exemplary compound d)
) was dissolved in 1000 m of 1,2-dichloroethane and applied to the charge generating material using a dip coating method to obtain a solution containing about 0-21 u% of 4f1,2-dichloroethane.
A charge transport layer having a thickness of about 18p was formed by controlling the drying conditions so that the photoreceptor of the present invention was obtained. This is designated as sample l.

Example 2 In Example 1, the charge generating substance was exemplified compound G-1.
G-12 was used instead of 8, Exemplified Compound A was used instead of Exemplified Compound D as the charge transport substance, and the drying conditions were controlled so that the content of 1,2-dichloroethane was about 0.5 positive ffi%. A charge transport layer having a thickness of 18 µm was formed to obtain a photoreceptor of the present invention. This is called sample 2.

Example 3 In Example 2, the content of 1,2-dichloroethane was about 1
．． A photoreceptor of the present invention was obtained in the same manner except that the drying conditions were controlled so that the drying content was 0% by weight. This is called sample 3.

Example 4 A photoreceptor of the present invention was obtained in the same manner as in Example 2 except that chloroform was used instead of 1,2-dichloroethane. This is called sample 4.

Example 5 A photoreceptor of the present invention was obtained in the same manner as in Example 3, except that 1.1.2-trichloroethane was used instead of 1.2-dichloroethane. This was designated as Sample 5.

Example 6 10g of polyvinyl formal resin was added to Improper Tool 1
00h, and applied to an aluminum-deposited polyethylene terephthalate film by a roll coater coating method to form an undercoat layer having a film thickness of 77.18 Jj, ts. Next, a charge generation layer similar to that in Example 2 was formed on the undercoat layer by a wire bar coating method, and a charge transport layer similar to that in Example 2 was further formed by a plate coating method, but in the same manner as in Example 2. A photoreceptor of the present invention was obtained. This is called sample 6.

Example 7 A photoreceptor of the present invention was obtained in the same manner as in Example 6 except that 1.1.2) dichloroethane was used instead of 1.2-dichloroethane. This is called sample 7.

Comparative Examples 1 to 4 In Examples 1, 2, and 4.5, 1,2-dichloroethane, chloroform, 1.1,2 contained in the photosensitive layer
) A photoreceptor of the present invention was obtained in the same manner except that the drying conditions were controlled so that the amount of dichloroethane was less than 0.01 i1%. Compare this with samples 1, 2, 3.4
shall be.

Comparative Example 5 A photoreceptor of the present invention was obtained in the same manner as in Example 2, except that the drying conditions were controlled so that the amount of 1,2-dichloroethane contained in the photosensitive layer was 10% by weight. This will be referred to as comparative sample 5.

Comparative Example 6 A photoreceptor of the present invention was obtained in the same manner as in Example 3 except that tetrahydrofuran was used instead of 1,2-dichloroethane. This will be referred to as comparative sample 6.

Comparative Example 7 A photoreceptor of the present invention was obtained in the same manner as in Example 3 except that dioxane was used instead of 1,2-dichloroethane. This will be referred to as comparative sample 7.

[Evaluation] Samples 1 to 7. Comparative samples 1 to 7 were analyzed using Paper Analyzer 5P-428 (manufactured by Kawaguchi Electric Co., Ltd.) at 40% A.
The surface potential immediately after charging [VA
], surface potential after being left in the dark for 5 seconds [V+], surface illuminance exposed to 2 lux, exposure amount until surface potential becomes 1/2 V+ [E l/2 ]
(Lux-8ee), surface potential after 10 seconds exposure [VR
] was obtained, and the dark decay rate [D] was further obtained from the formula: -vID=X100 VA. In addition, a normal Carlson process was carried out, and the difference in surface potential immediately after the initial charging and after 10,000 charging cycles [ΔVal], and the residual potential after 10,000 charging cycles [VR'] were determined. These results are shown in Table-1.

As is clear from these tables, the photoreceptor of the present invention is an excellent photoreceptor with low potential retention and little fluctuation due to repeated use.

[Brief explanation of the drawing]

1 to 8 are schematic sectional views showing embodiments of the layer structure of the photoreceptor of the present invention. In the figure, 1 is a conductive substrate, 2 is a charge generation layer, 3 is a charge transport layer, 4 is an undercoat layer, and 5 is a photosensitive layer. Patent applicant: Roku Konishi Photo Industry Co., Ltd. Agent
Patent attorney Nobuaki Sakaguchi (and 1 other person) @1 diagram Nephew 5 diagrams

Claims (1)

[Claims] A photoreceptor comprising at least a photosensitive layer formed on a conductive substrate, characterized in that the photosensitive layer contains a halogen-containing solvent.