JPS6141152A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body enhanced in adhesion between an electrostatic charge transfer layer and a substrate and superior in durability and the like by using a binder contg. a thermoplastic resin, an epoxy resin, and an epoxy resin hardener in the charge transfer layer. CONSTITUTION:The charge transfer layer is formed by using a binder contg. a thermoplastic resin, such as especially durable polycarbonate or polyacrylate resin, in an amt. of 20-300wt% of the charge transfer material, and an epoxy resin for enhancing adhesion in an amt. of 0.01-10wt% of the total weight of the charge transfer layer, and further, a hardener for enhancing the adhesion of the epoxy resin in an amt. of 0.1-1,000wt% of the epoxy resin. The charge transfer layer thus formed is laminated on a charge generating layer formed on the substrate or between them to enhance the adhesion between the substrate and the charge generating layer and to enhance toughness of them, thus permitting an electrophotographic sensitive body superior in electrophotographic characteristics and durability to be obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electrophotographic photoreceptor having a conductive layer, a charge generation layer containing an organic pigment that generates charges, and a charge transport layer having charge retention and transport functions. In particular, the present invention relates to an electrophotographic photoreceptor with improved adhesion of a charge transport layer.

(Prior Art) In an electrophotographic photoreceptor that uses a photoconductive substance as a photosensitive material, the conductive substance is conventionally used.

Inorganic conductive substances such as selenium, zinc oxide, titanium oxide, and cadmium sulfide have been mainly used.

However, many of these are generally highly toxic.

There are also problems with the method of disposal.

Photosensitive materials that use some organic photoconductive compounds are generally less toxic than those that use inorganic photoconductive substances, and are also superior in terms of transparency, flexibility, lightness, and price. Due to its advantages, it has recently been widely studied.

Among them, composite photoreceptors that separate the functions of charge generation and transport have been rapidly gaining popularity in recent years because they can significantly improve the sensitivity, which is a major drawback of conventional photoreceptors using organic conductive compounds. Continue to make progress.

(Problems to be Solved by the Invention) When these composite photoreceptors are applied to an electrophotographic device using the Carlson method, an electrostatic latent image is first formed on the surface of the photoreceptor, and then the image is charged with an opposite sign. Transferring the toner image to another substrate 1, such as paper, using a developer generally called a toner,
It is fixed and you can get a copy. At this time, it is necessary to remove (cleaning) the slight amount of toner remaining on the surface of the photoreceptor using a brush, blade, or the like.

Due to the repeated development, transfer, and cleaning steps, the surface of the photoreceptor is worn and damaged, resulting in the transferred image becoming unclear.

In some cases, the life of the photoreceptor is significantly shortened due to peeling of the charge transport layer or charge generation layer. Due to these problems, photoreceptors are required to have strong durability.

To this end, attempts have been made to improve wear resistance by hardening the charge transport layer, which is usually the surface layer of a composite two-layer electrophotographic photoreceptor, and to provide a hard protective layer on the surface of the electrophotographic photoreceptor. ing.

However, although the latter method of forming a protective layer improves abrasion resistance, it tends to increase the residual potential and decrease sensitivity in electrophotographic characteristics, and decreases productivity because the process of forming the protective layer increases. For these reasons, this is not necessarily a preferable method.

In order to improve the abrasion resistance of the charge transport layer as the surface layer of the former, it is possible to use a heat and/or photocurable resin as a binder for the charge transport layer, but in this case, the abrasion resistance is Although improved, the electrophotographic characteristics deteriorate. Therefore, in order to avoid these drawbacks, Japanese Patent Application Laid-Open No. 52-12083
As disclosed in Publication No. 4 and Japanese Patent Application Laid-Open No. 54-48555, thermoplastic resins such as polycarbonate resins and polyarylate resins that can form a hard and tough film simply by volatilizing the solvent are charged. Its use as a binder in transport layers is conventionally practiced.

However, these resins have a problem in that they have poor adhesion to the base and are easily peeled off.

Therefore, it is an object of the present invention to solve the above-mentioned problems, improve the adhesion of the charge transport layer, and provide an electrophotographic photoreceptor with excellent electrophotographic properties, durability, and adhesion. .

(Means and effects for solving the problems) The present invention solves the above problems by using a specific binder in the charge transport layer.

Specifically, the present invention provides an electrophotographic photoreceptor having a conductive layer, a charge generation layer containing an organic pigment that generates a charge, and a charge transport layer having charge retention and transport functions, in which a thermoplastic resin and an epoxy resin are used in the charge transport layer. The present invention relates to an electrophotographic photoreceptor containing a resin or a cured product thereof.

The materials used in the electrophotographic photoreceptor according to the present invention will be described in detail below.

First, in the present invention, the conductive layer refers to paper or plastic film treated for conductivity, or a plastic film laminated with metal foil such as aluminum.

It is a conductor such as a metal plate.

Organic pigments that generate charges and are included in the charge generation layer include azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinone, indigoid, quinacridone, phthalocyanine, perylene, and methine. Pigments known to generate charges such as can be used. These pigments are 1, for example, JP-A-47-3
No. 7453, JP-A-47-37544, JP-A-47-
No. 18543, JP-A-47-18544, JP-A-48
-43942, JP-A-48-70538, JP-A-4
9-1231, JP-A-49-105536, JP-A-50-75214, and JP-A-50-92738.

In particular, the
τ', η and η' type gold metal 7 talocyanine It has high sensitivity up to long wavelength K and is effective as an electrophotographic photoreceptor for printers equipped with diode lasers. In addition to these, any organic pigment that generates a stain carrier upon irradiation with light can be used.

As the charge transporting substance which is the main component of the charge transport layer, polymer compounds include poly-N-vinylcarbazole, halogenated holy-N-vinylcarbazole, poly and nylpyrene, polyvinylindoquinoxaline, polyvinylbenzothiophene, polyvinylanthracene, Polyvinylacridine, polyvinylpyrazoline, etc. are used as low molecular weight compounds such as fluorene, fluorenone, 2.7-sinitro-9-fluorenone, 2,4.7-)dinitro-9-fluorenone, and 4H-indeno(1,2,6)thiophene. -4-off, 3,7-sinitrodibenzothio7ene-5-oxide, 1-bromopyrene, 2-phenylpyrene, carbazole, 3-phenylcarbazole.

2-phenylindole, 2-phenylnaphthalene, oxadiazole, oxatriazole, 1-phenyl-
3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, 2-phenyl-4-
(4-Diethylaminophenyl) -5-phenyloxazole 1) IJ Examples include phenylamine, imidazole, chrysene, tetra7ene, acridene, and derivatives thereof.

Further, additives such as a binder, a plasticizer, a fluidity imparting agent, and a pinhole suppressing agent, which are commonly used in electrophotographic photoreceptors, can be added to the charge generation layer as necessary. Silicone resin is used as a binder.

Polyamide resin, polyurethane resin, polyester resin, polycarbonate resin, polyketo/resin, polycarbonate resin, polystyrene resin, polymethyl methacrylate resin,
Examples include polyacrylamide resin. Thermosetting and photocuring resins that are crosslinked by heat and/or light can also be used.

In any case, there is no particular restriction as long as the resin is insulative and can form a film under normal conditions. Examples of the plasticizer include halogenated paraffin, dimethylnaphthalene, dibutyl phthalate, and the like. Examples of the fluidity imparting agent include Modaflow (manufactured by Monosand Chemical Co.) and Acronal 4F (manufactured by Bass 7 Co., Ltd.), and examples of the pinhole inhibitor include benzoin, dimethyl heptatalate, and the like.

These can be selected and used as appropriate, and the amount thereof can also be determined as appropriate.

In the charge generating layer, the binder has a content of 300% relative to the organic pigment.
Weight - Use in the following amounts. If you exceed 300 weight,
Electrophotographic properties deteriorate.

In addition, the charge transport layer also contains a plasticizer, as well as the charge generation layer.
Additives such as fluidity imparting agents and pinhole inhibitors can be added.

In the present invention, the thermoplastic resin used as a binder in the charge transport layer includes silicone resin, polyamide resin,
Polyester resin, polyketone resin, polystyrene resin, polycarbonate resin.

Polyacrylate resin, polymethyl methacrylate resin,
Examples include polyacrylic oxide, but highly durable polycarbonate resins, polyacrylate resins, and the like are particularly advantageous. These resins.

It is used in an amount of 20 to 300% by weight based on the charge transport material.

If the weight is less than 20%, the durability of the charge transport layer will be poor;
If it exceeds 0% by weight, photographic properties will deteriorate.

Further, in the present invention, the epoxy resin added to improve the adhesion of the charge transport layer is as follows.

Examples include those having the following structure.

c) (3) Phenol novolac type epoxy resin, cresol-reduced epoxy resin.

\0' Cycloaliphatic epoxy resins such as.

Heterocyclic epoxy resins such as ethylene glycol.

Polyglycidyl ethers of polyhydric alcohols such as glycerin.

(Here, 9m indicates an integer from 1 to 5) etc.

The epoxy resin can be present in the charge transport layer by itself or as a cured product cured with a curing agent.

Here, as the curing agent, polymethylene diamine, polyether diamine, 1,3-diaminocyclohexane,
Aliphatic amines such as inphorondiamine, m-phenylenediamine, diaminodiphenyl ether, 2,6-diamitupyridine, aromatic amines such as m-aminobenzylamine, N-methylpiperazine, hydroxyethylpiperazine, morpholine, 2-dimethyl Secondary or tertiary amines such as amino-2-hydroxypropane, benzyldimethylamine, 1-hydroxyethyl-2-heptadecylglyoxalidine, phthalic anhydride, maleic anhydride,
Acid anhydrides such as succinic anhydride and methyltetrahydrophthalic anhydride, polyamide resins.

Polysulfide resin, boron trifluoride-monoethylamine complex, dicyandiamide, etc. others.

Silicone modified versions of the above compounds can be used.

The amount of epoxy resin added is 0.01 for the charge transport layer.
-10% by weight, preferably 0.1-3% by weight. If the amount of the epoxy resin added is less than 0.01 weight, there is no effect on improving adhesion, and if it exceeds 10 weight, the electrophotographic properties will deteriorate and the compatibility with the binder will deteriorate.

Adding 0.01 to 10% by weight of epoxy resin to the charge transport layer improves adhesion, but if a curing agent is used in combination, the effect of improving adhesion is further increased. In this case, the amount of curing agent added is 0.1% to 1% by weight based on the epoxy resin.
The amount is preferably in the range of 0.000% by weight, and can be appropriately determined depending on the relationship between the epoxy resin and curing agent used. Preferably, the amount of reactive groups in the curing agent is equal or less to the epoxy groups of the epoxy resin.

The electrophotographic photoreceptor of the present invention is formed by forming a charge generation layer on a conductive layer and forming a charge transport layer thereon, or by laminating the charge generation layer and the charge transport layer in the reverse order.

The thickness of the charge generation layer is 0.01 to 10 μm, preferably 0.01 to 10 μm.
．． It is 2 to 5 μm. Less than 0.01 μm.

It is difficult to form a charge generation layer uniformly.

If it exceeds 10 μm, electrophotographic properties tend to deteriorate. Further, the thickness of the charge transport layer is preferably 5 to 50 μm.
, particularly preferably 8 to 20 μm. When the thickness is less than 5 μm, the initial potential tends to decrease, and when it exceeds 50 μm, the sensitivity tends to decrease.

To form the charge generation layer and the charge transport layer, the components of each layer are uniformly dissolved or dispersed in a ketone solvent such as acetone or methyl ethyl ketone, an ether solvent such as tetrahydrofuran, or an aromatic solvent such as toluene or xylene. rear,
Coated on the conductive layer.

dry. In order to incorporate the cured epoxy resin into the charge transport layer, the epoxy resin, curing agent, and other components are uniformly dissolved or dispersed in a solvent.

Coat on the conductive layer, cure and dry. At this time, in order to cure the epoxy resin, a temperature suitable for the curing reaction of the epoxy resin can be appropriately selected and employed.

The electrophotographic photoreceptor of the present invention may further have a thin adhesive layer or barrier layer immediately above the conductive layer. Further, a protective layer can also be provided on the surface of the photoreceptor.

To perform copying using the electrophotographic photoreceptor of the present invention,
As in the past, after charging and exposing the surface of 9, development is performed, and the image is transferred onto plain paper and fixed.

(Function) In the present invention, a thermoplastic resin and an epoxy resin or a cured product thereof are contained in the charge transport layer.

When a charge generation layer and a charge transport layer are laminated in this order on a conductive layer, the interface between the charge generation layer and the charge transport layer, and when the charge generation layer and charge transport layer are reversed, the conductive layer and the charge transport layer.

(Example) Next, the present invention will be described in detail based on Examples and Comparative Examples, but the present invention is not limited thereto.

Each material used in the examples below is listed below.

(1) Organic pigment τW111k gold 87 talocyanine (τ-H, PC) (2
) Charge transporting substance 2-(p-dimethylamino)phenyl-4-(p-dimethylamino)phenyl-5-(o-chlorophenyl)-
1,3-Oxazole (OXZ) (3) Binder silicone varnish: KR-255 [Shin-Etsu Chemical ■Product name] Polycarbonate resin: Panlite L-1250 [Teijin Kasei Kogyo ■Product name] (4) Epoxy resin Epicoat 1004 (EP-1004) Epoxy equivalent weight 9
00-1000 [Shell Chemical ■Product name] Epicoat 1009 (BP-1009) Epoxy equivalent 2400-3300 [Shell Chemical ■Product name] (5) Curing agent 2-ethyl-4-methylimidazole (EMI) Silicone-modified amine (S几-2115K) [Tone Silicone Trade Name] Comparative Example 1 2.0 g of τ-H2PC, Silicone Fes 409, and Tetrahydrofuran 949 were kneaded for 8 hours using a ball mill (3-inch pot mill manufactured by Nippon Kagaku Togyo Co., Ltd.). The obtained pigment dispersion was applied to an aluminum plate (thickness 0) using an applicator.
．． 1 m) Coat the top and dry at 100°C for 15 minutes to form a charge generation layer with a thickness of 1 μm.

Next, OXZ 5 G and polycarbonate resin 159 were mixed with 2140 g of methine chloride and completely dissolved. The resulting coating liquid was applied onto the charge generation layer using an applicator and dried at 90° C. for 20 minutes to form a charge transport layer with a thickness of 15 μm.

Examples 1 to 5 A charge generation layer was formed on the same aluminum plate as in Comparative Example 1 in the same manner as in Comparative Example 1.

The charge transport layer coating liquid shown in Comparative Example 1 was further mixed with an epoxy resin and a curing agent in the proportions shown in Table 1 below, and after completely dissolving, a charge transport layer was prepared in the same manner as in Comparative Example 1. were laminated.

The electrophotographic properties and adhesion of the obtained electrophotographic photoreceptor were tested, and the results are shown in Table 1.

The electrophotographic characteristics were measured using an electrostatic recording paper tester (5P manufactured by Kawaguchi Electric).
-428).

The initial potential (Vo) in Table 1 is 1
Dark decay (Vk) represents the surface potential when discharged for 0 seconds.
indicates the potential attenuation when the sample is left in a dark place for 30 seconds, and the half-reduction exposure (E50) is the amount of light required to reduce the potential to half by irradiating it with 10JX of white light (unit: l).
x).

Further, adhesion was determined by making a mesh-like scratch on the surface of 9 in advance with a knife, and performing a peel test using Sellotape, and indicating the presence or absence of peeling.

As shown in Table 1, the photoreceptor of Comparative Example 1 had poor adhesion and peeled off easily, but the electrophotographic photoreceptors of the present invention shown in Examples 1 to 5 had good adhesion and In terms of photographic properties, initial potential and dark decay are also improved.

Below (Effects of the Invention) According to the present invention, an electrophotographic photoreceptor with significantly improved adhesion between each layer can be obtained, and this photoreceptor also has excellent electrophotographic properties, low initial potential and dark decay. improves.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a conductive layer, a charge generation layer containing an organic pigment that generates a charge, and a charge transport layer having charge retention and transport functions, the charge transport layer contains a thermoplastic resin, an epoxy resin, or a hardened resin thereof. An electrophotographic photoreceptor containing a substance.