JPH06186767A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body with an under-layer excellent in adhesion of the photosensitive layer to the electric conductive substrate, having high sensitivity and also excellent in mechanical characteristics at the time of coating. CONSTITUTION:This electrophotographic sensitive body has an underlayer between the electric conductive substrate and the photosensitive layer. The underlayer contains two or more kinds of nylon resins each soluble in a solvent and contg. N-alkoxymethylated nylon 12 as an essential component. Alumina coated fine titanium oxide powder is preferably dispersed in the underlayer because enhanced characteristics and an interference fringe preventing effect are ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having an undercoat layer, and more particularly, to an undercoat film having improved sensitivity and improved mechanical properties as compared with conventional materials for forming an undercoat layer. The present invention relates to an electrophotographic photoreceptor having a layer.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member has a basic structure in which a photosensitive layer is formed on a conductive support. However, the adhesion of the photosensitive layer, the coating property, the charging property, the support from the support are improved. An undercoat layer is provided to prevent unnecessary charge injection, protect against electrical breakdown, or cover defects on the support. Conventionally, as the undercoat layer, for example, polyvinyl methyl ether, poly-N-vinyl imidazole, polyethylene oxide, methyl cellulose,
Ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, casein, gelatin, polyethylene, polyester, phenol resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinylpyrrolidone, polyvinylpyridine, polyurethane, polyglutamic acid, polyacrylic acid, etc. It is known to use the above resin material.

Among these resin materials, a soluble polyamide resin is particularly preferred (Japanese Patent Laid-Open No. 5-5120).
1-114132, 52-25638, 56-
21129, 58-95351, etc.). Further, among these, N-alkoxymethylated nylon described in JP-A-58-95351 is a material having a good balance of various characteristics and is used as a preferable material. By the way, conventionally, as the N-alkoxymethylated nylon in the undercoat layer, nylon 6 is mainly used. N-alkoxymethylated nylon has different physical properties depending on the type of nylon to be alkoxymethylated, and when they are used in the undercoat layer, the characteristics of the photoconductor differ little by little, and always obtain satisfactory results. Was not.

The present inventor has studied various N-alkoxymethylated nylon resins and found that nylon 12
It was found that N-alkoxymethylated is particularly preferable, and a patent application was filed as Japanese Patent Application No. 3-254235 for an electrophotographic photoreceptor using this as an undercoat layer. However, the electrophotographic photoreceptor having the N-alkoxymethylated nylon 12 as the undercoat layer has good electrical characteristics such as chargeability and sensitivity, but is weak in mechanical characteristics such as scratch resistance and abrasion resistance. There is a property. Therefore, when applying the photosensitive layer on the undercoat layer, if it is applied by a coating means such as a wire bar coater or a ring coater that makes mechanical contact with the undercoat layer, a scratch may occur depending on the conditions. there were.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is to provide not only electrical characteristics such as sensitivity but also a conductive support and a photosensitive layer. Another object of the present invention is to provide an electrophotographic photosensitive member having an undercoat layer which is excellent in adhesiveness and mechanical properties during coating.

[0006]

As a result of further research on various materials for forming an undercoat layer, the present inventor has used N-alkoxymethylated nylon 12 in combination with another solvent-soluble nylon resin as the undercoat layer. By doing so, it was found that the mechanical properties were improved without impairing the electrical properties of the N-alkoxymethylated nylon 12, and the present invention was completed. That is, the electrophotographic photoreceptor of the present invention has an undercoat layer between a conductive support and a photosensitive layer, and comprises two or more solvent-soluble nylons containing N-alkoxymethylated nylon 12 as an essential component. A resin is contained in the undercoat layer.

The present invention will be described in detail below. In the present invention, the conductive support is aluminum,
Metallic drums and sheets of copper, stainless steel, etc., plastic films, papers, etc. laminated with metal foils of aluminum, etc., or aluminum, gold, etc. vapor-deposited, and those that have been subjected to a conductive treatment are mentioned. The surface of the conductive support can be subjected to various treatments within a range that does not affect the image quality. For example, surface oxidation treatment, chemical treatment, or the like can be performed.

The subbing layer on the conductive support is composed of two or more solvent-soluble nylon resins containing N-alkoxymethylated nylon 12 as an essential component, that is, nylon 12 is N-.
It is formed using alkoxymethylated nylon resins and other solvent soluble nylon resins. Specific examples of the N-alkoxymethylated nylon 12 include methoxymethylated, ethoxymethylated, propoxymethylated and butoxymethylated nylon 12.
Such a nylon resin also includes a copolymer containing nylon 12, such as nylon 6-12, 66-12.
10-12,610-12 copolymer, nylon 6-66
-12,6-610-12 copolymer, nylon 6-66
A nylon resin obtained by N-alkoxymethylating a -610-12 copolymer or the like can be mentioned.

As another solvent-soluble nylon resin, a copolymerized nylon resin itself containing nylon 6 as a copolymerization component, N-alkoxymethylated nylon 6 or a copolymer containing nylon 6 is preferably used. Specifically, nylon 6-66,6-10,6-610 copolymer, nylon 6-66-10,6-66-610,6
-66-12, 6-10-12, 6-610-12 copolymer, nylon 6-66-610-12 copolymer and the like, and further N-alkoxymethylated nylon 6 and nylon 6
-66,6-10,6-610 copolymer, nylon 6-
Examples thereof include copolymer nylon resins obtained by N-alkoxymethylating a 66-10,6-66-610 copolymer and the like. These N-alkoxymethylated nylon 12 and other solvent-soluble nylon resins can be used alone or in admixture of two or more.

When the subbing layer does not contain N-alkoxymethylated nylon 12, for example, N-alkoxymethylated nylon 6 alone produces an electrophotographic photosensitive member whose electrical characteristics are better than those of N-alkoxymethylated nylon 12 alone. Inferiority, only the copolymerized nylon resin which is not N-alkoxymethylated modified is further inferior in electrical properties, which is remarkable especially under low humidity. The mixing ratio of N-alkoxymethylated nylon 12 and other solvent-soluble nylon resin is
A range of 1:10 to 2: 1, preferably 1: 5 to 1: 1 is suitable. When the amount of the former is small, the electrical characteristics deteriorate, and when it is too large, the effect of improving the mechanical characteristics becomes small.

To form the undercoat layer, a solution obtained by dissolving the above-mentioned two or more solvent-soluble nylon resins in an alcohol solvent may be applied. As the alcohol solvent, for example, methanol, ethanol, n-propanol, i-propanol, butanol or the like is used. You may use 2 or more types of alcohol. The dissolution of the nylon resin in the solvent in the present invention is easily carried out within the range of the above mixing ratio. That is, unlike the case of N-alkoxymethylated nylon 6 alone, it is not necessary to take the complicated method of first dissolving it in methanol heated to 40 ° C. and then mixing with another alcohol, and adding it directly to the mixed solvent. Only dissolves.

The undercoat layer may contain alumina-coated titanium oxide fine particles as described in JP-A-2-181158. When alumina-coated titanium oxide is dispersed in the undercoat layer, the dielectric constant of titanium oxide is high, so that the dielectric constant of the undercoat layer can be increased and a thick film can be formed. Thereby, the dispersibility can be improved. Moreover, the undercoat layer in which the titanium oxide coated with alumina is dispersed has a high effect of concealing the conductive support, and some scratches do not pose a problem. Further, the scattering effect on incident light is high, and even if coherent light such as laser light is incident, interference does not occur. This is an effect due to the high refractive index of titanium oxide, and it is possible to obtain a photoconductor that does not cause interference fringes.

The alumina-coated titanium oxide fine particles used in the present invention can be produced, for example, as follows. Titanium oxide fine particles having a particle size of about 0.1 to 0.8 μm are dispersed in an aqueous solution of an aluminum salt such as aluminum chloride, and alkali such as caustic soda is added thereto to generate colloidal aluminum hydroxide.
Then, the titanium oxide fine particles are strongly heated at about 500 ° C. to obtain alumina-coated titanium oxide fine particles.
The amount of alumina coated is 1 to 1 with respect to titanium oxide.
About 0% by weight is preferable. The compounding ratio of the alumina-coated titanium oxide fine particles and the solvent-soluble nylon resin is 4: 1.
The range of to 1: 4 is preferable. When the latter ratio is large, the effect of increasing the film thickness of the undercoat layer is small, and when the former ratio is large, the film forming property and strength of the coating film of the undercoat layer become insufficient.

In order to obtain a coating liquid containing alumina-coated titanium oxide fine particles, alumina-coated titanium oxide fine particles are added to an alcohol solution of a polyamide resin, and a ball mill, roll mill, sand mill, paint shaker, attritor, ultrasonic wave or the like is used. It may be processed by means.
For example, about 30 minutes is sufficient for this dispersion treatment in the case of a sand mill.

In the electrophotographic photoreceptor of the present invention, a photosensitive layer is formed on the undercoat layer. The photosensitive layer may have a single layer structure, but preferably has a laminated structure in which a charge generation layer and a charge transport layer are functionally separated. When the photosensitive layer has a single layer structure, a known photosensitive layer in which a photosensitive material is dispersed in a binder resin may be used. Examples thereof include a dye-sensitized ZnO photosensitive layer, a CdS photosensitive layer, and a photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder resin.

When the photosensitive layer has a laminated structure, the charge generation layer and the charge transport layer are sequentially laminated on the undercoat layer. The charge generating layer and the charge transporting layer are formed by dispersing the charge generating substance and the charge transporting substance in a binder resin dissolved in a solvent as necessary. Examples of the charge generating substance include selenium, selenium alloy, CdS, CdSe, CdSS.
e, ZnO, ZnS, and other inorganic photoconductive materials, metal or metal-free phthalocyanine pigments, squarium compounds, azurenium compounds, perylene pigments, indigo pigments, quinacridone pigments, polycyclic quinone pigments, cyanine dyes, and other organic photoconductive materials. Can be mentioned. As the binder resin, for example,
Polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymer or copolymer thereof, vinyl acetate polymer or copolymer thereof,
Cellulose ester or ether, polybutadiene,
Polyurethane, epoxy resin, etc. are used. The thickness of the charge generation layer is generally 0.1 to 5 μm, preferably 0.2.
˜2.0 μm is suitable.

The charge transport material is not particularly limited as long as it is transparent to visible light and has a charge transport ability. Specifically, imidazole,
Pyrazoline, thiazole, oxadiazole, oxazole, hydrazone, ketazine, azine, carbazole,
Examples thereof include polyvinylcarbazole and the like and derivatives thereof, triphenylamine derivatives, stilbene derivatives, benzidine derivatives and the like. The binder resin may be any resin as long as it has a film-forming property, for example,
Polycarbonate, polyarylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylic acid ester, styrene-methacrylic acid ester copolymer and the like are used. The film thickness of the charge transport layer is preferably about 5 μm to 30 μm.
When the photosensitive layer has a laminated structure, the order of laminating the charge generation layer and the charge transport layer may be reversed.

[0018]

The nylon resin, which is an essential component of the material for forming the undercoat layer, is N-alkoxylated from nylon 12 as a raw material. Therefore, the solubility of nylon 12 in a solvent is increased and the solution is less likely to gel. And the undercoat layer containing this N-alkoxymethylated nylon 12 is
When the photosensitive layer is formed, the coating solvent for the photosensitive layer easily permeates, resulting in a concentration gradient at the interface between the undercoat layer and the photosensitive layer.
That is, a boundary region in which the both are mixed is formed without forming a clear layered structure, which in turn brings about a good result in electrical characteristics and the like, and improves the quality such that charges easily flow. Further, the electrophotographic photosensitive member of the present invention in which the above nylon resin is used in combination with another solvent-soluble nylon resin has substantially no change in the electrical characteristics and only the mechanical characteristics are improved.
This is because the N-alkoxymethylated nylon 12 and other solvent-soluble nylon resin are mixed in the undercoat layer, and the flexible solvent of the N-alkoxymethylated nylon 12 makes the coating solvent for the photosensitive layer more It is presumed that not only it becomes easy to penetrate, but also the excellent mechanical properties inherent to other solvent-soluble nylon resins appear.

[0019]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The following "parts" mean "parts by weight". Example 1 2 parts of N-methoxymethylated nylon 12 (trade name: Toresin G550, manufactured by Teikoku Chemical Industry Co., Ltd.) and N-methoxymethylated nylon 6 (trade name: Toresin F30, manufactured by Teikoku Chemical Industry Co., Ltd.) 4 parts methanol 60 parts and n
-Dissolved in 34 parts butanol. A mirror-cut aluminum pipe of 84 mmφ × 310 mm was prepared as a conductive support, and the above solution was applied to the surface of the aluminum pipe by a ring coater and dried at 120 ° C. for 10 minutes to give a film thickness of 1.
An undercoat layer of 0 μm was formed. Next, polyvinyl butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) 1
Parts were dissolved in 19 parts cyclohexanone. To this solution, 8 parts of dibromoanthanthrone pigment (CI Pigment Red 168) and 0.02 part of trifluoroacetic acid were mixed, and a dispersion treatment was performed by a sand mill using 1 mmφ glass beads as a dispersion medium. Cyclohexanone was further added to the obtained dispersion liquid to prepare a coating liquid having a solid content concentration of about 10%. This coating solution was applied onto the above-mentioned undercoat layer by a ring coater and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a film thickness of 0.8 μm. Then N,
4 parts of N'-diphenyl-N, N'-bis (m-tolyl) benzidine was used as a charge transport material and dissolved in 40 parts of monochlorobenzene together with 6 parts of polycarbonate Z resin.
The obtained solution was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 1 hour to form a charge transport layer having a film thickness of 20 μm. An electrophotographic photosensitive member was produced as described above. In the manufacturing process, no problem occurred even if 20 layers were repeatedly applied to form the charge generation layer.

Comparative Example 1 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 6 parts of N-methoxymethylated nylon 12 (Toresin G550) was used as the material for forming the undercoat layer. When the charge generation layer was formed by repeating the coating operation in the manufacturing process, streaks began to appear from the 12th coating layer. This is because the polyethylene ring in contact with the undercoat layer in the ring coater was damaged by repeated application, causing scratches on the undercoat layer.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 6 parts of a quaternary copolymer nylon resin (trade name: CM8000, manufactured by Toray Industries, Inc.) was used as the material for forming the undercoat layer. Was produced. Comparative Example 3 Example 1 was repeated except that 6 parts of N-methoxymethylated nylon 6 (Toresin F30) was used as the material for forming the undercoat layer.
An electrophotographic photosensitive member was produced in the same manner as. However, when the nylon resin was dissolved, a method was used in which it was dissolved in methanol heated to 40 ° C. and then butanol was added.

For each electrophotographic photosensitive member produced, -8
Charged with a scorotron charger having a grid held at a constant voltage of 20V (A), after 1 second 9.0 erg / c
The potential of each part was measured by a process of irradiating m ² of white light for discharging (B), and after 3 seconds of irradiating with 50 erg / cm ² of green light for static elimination (C). It can be said that the higher the potential (A) is, the higher the receptive potential of the photoconductor is, so that the injection of unnecessary charges is reduced. It can be said that the lower the potential (B) is, the higher the sensitivity is, and the lower the potential (C) is, the less the residual charge is, the less the image memory or the fog is.

For each electrophotographic photosensitive member, 55 ° C.
The results of these measurements at% RH are shown in Table 1.

[Table 1]

Next, Table 2 shows the same measurement results at 15 ° C. and 15% RH.

[Table 2] From the above results, the photoreceptors of Example 1 and Comparative Example 1 were
The sensitivity is higher than those of Comparative Examples 1 and 2, and the decrease in sensitivity is small even in an environment of low temperature and low humidity. However, as described above, Example 1 was superior to Comparative Example 1 from the viewpoint of the occurrence of scratches during repeated coating by the ring coater.

Example 2 A 50 mm thick polyester film vapor-deposited with aluminum was prepared as a conductive support. The same coating solution as in Example 1 was applied to this surface with a # 4 wire bar to form an undercoat layer. Further, the same charge generation layer forming coating solution as in Example 1 was applied thereon by a # 3 wire bar, and then an electrophotographic photosensitive member was produced in the same manner as in Example 1. Comparative Example 4 An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the undercoat layer was formed using the same coating solution as in Comparative Example 1.

Table 3 shows the state of the surface of the charge generation layer after coating of the electrophotographic photosensitive members produced in Example 2 and Comparative Example 4.

[Table 3] As described above, when only N-methoxymethylated nylon 12 is used as the material for forming the undercoat layer, the surface of the charge generation layer is easily scratched, but when N-methoxymethylated nylon 6 is used in combination, scratches are generated. No longer attached.

Example 3 N-methoxymethylated nylon 12 (Toresin G55
0) 3 parts and quaternary copolymer nylon resin (CM800
0) Example 1 except that the undercoat layer was formed using 3 parts
An electrophotographic photosensitive member was produced in the same manner as. In the production process, the coating operation was repeated to form the charge generation layer, but no problem occurred as in Example 1.

Example 4 An alumina-coated titanium oxide powder (trade name: SR-1T, manufactured by Sakai Chemical Industry Co., Ltd.) was added to the undercoat layer coating solution prepared in Example 1.
(Made by Japan) was added twice as much as the resin content, and then dispersed together with 2 mmφ glass beads by a paint shaker for 30 minutes. A 60 mmφ × 260 mm mirror-finished aluminum pipe is prepared as a conductive support, and the surface of the aluminum pipe is coated with the above dispersion liquid and dried at 120 ° C. for 10 minutes to obtain a film thickness of 3.0 μm. Layers were formed. Next, polyvinyl butyral resin (S-REC B
3 parts of x-type metal-free phthalocyanine was mixed with a solution prepared by dissolving 3 parts of M-1) in 100 parts of cyclohexanone in advance, and subjected to dispersion treatment for 5 hours by a sand mill. Then, it was diluted with cyclohexanone to prepare a charge generation layer forming coating liquid having a solid content concentration of 3.5% by weight. This coating solution was applied onto the undercoat layer by a ring coater and dried at 100 ° C. for 10 minutes to form a charge generation layer having a film thickness of 0.25 μm. Further, a charge transport layer was formed thereon in the same manner as in Example 1.

With respect to the electrophotographic photosensitive member thus produced, the following characteristics were obtained by a printer having an electrophotographic process such as -600 V charging, image exposure with a semiconductor laser, reversal development with a negatively charged developer, and transfer to paper. Was evaluated. When the potential of the light irradiation part was measured, -100
It was V. There was no problem even if I tried to print out images with various patterns. In addition, even if ten photoconductors were continuously produced, the tenth photoconductor had the same performance as the first photoconductor.

Comparative Example 5 An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that only N-methoxymethylated nylon 12 (Toresin G550) was used as the material for forming the undercoat layer. The performance of the photoconductor itself was the same as that of Example 4, but when the photoconductor was continuously produced, streaks began to appear in the undercoat layer from the fourth line.

Comparative Example 6 Only N-methoxymethylated nylon 6 was used as the material for forming the undercoat layer, and titanium oxide not coated with alumina-coated titanium oxide (trade name: R310, Sakai Chemical Industry Co., Ltd.). An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that (Production) was used. This photosensitive member was similar to that of Example 4 in terms of characteristics, but the stability of the dispersion liquid was poor, and when applied one day later, particles aggregated and became coarse, so that spots were conspicuously generated.

[0032]

The electrophotographic photoreceptor of the present invention uses two or more kinds of solvent-soluble nylon resins having N-alkoxymethylated nylon 12 as an essential component as the material for forming the undercoat layer. N-alkoxymethylated nylon 12 with high adhesion and high adhesion between support and photosensitive layer
In addition to its function, mechanical properties can be improved by using a solvent-soluble nylon resin other than Nylon 12, so even if the charge generation layer forming coating solution is repeatedly applied, streaks and scratches will not occur. I can't. Further, in the present invention, when alumina-coated titanium oxide is dispersed in the undercoat layer, the film thickness of the undercoat layer is increased (for example, 3.0 μm).
m), and has the effect of improving characteristics such as increasing the dielectric constant and preventing interference fringes.

Claims (3)

[Claims] 1. An electrophotographic photoreceptor having an undercoat layer between a conductive support and a photosensitive layer, wherein two or more kinds of solvent-soluble nylon resins containing N-alkoxymethylated nylon 12 as an essential component are undercoated. An electrophotographic photosensitive member characterized by being contained in a layer. 2. A solvent-soluble nylon resin other than N-alkoxymethylated nylon 12 is a copolymerized nylon resin containing nylon 6 as a copolymer component and a nylon resin obtained by N-alkoxymethylating nylon 6 or a copolymer thereof. The electrophotographic photoreceptor according to claim 1, which is at least one resin selected. 3. The electrophotographic photosensitive member according to claim 1, wherein alumina-coated titanium oxide fine particles are dispersed in the undercoat layer.