JPH03287274A - Manufacture of thin film and electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain this highly sensitive electrophotographic sensitive body by dispersing or dissolving a hydrophobic powder with the use of surfactant and by forming the film of the hydrophobic material on a cathode by energizing to the dispersion or the solution. CONSTITUTION:The powders of the hydrophobic material of <=10mum are dispersed or dissolved in an aqueous medium with the surfactant of 10.0-20.0 HLB value (excluding a ferrocene derivative) and then by energizing to the obtained dispersion or the solution at 40-80 deg.C, the film of a hydrohobic material is formed on the cathode. The hydrophobic material is preferably an electrostatic charge generating material. Thus the improvement of the film forming property, the uniformity of the formed film and the enhancement of the photosensitive characteristics can be attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a thin film and an electrophotographic photoreceptor;
In detail, we will explain how to efficiently produce a uniform thin film by using a surfactant with a specific HLB (hydrophilic-lipophilic balance) value and applying electricity under heating conditions, and how to efficiently produce a uniform thin film using this method. The present invention relates to a method of manufacturing an electrophotographic photoreceptor with excellent photosensitive characteristics by forming a charge generation layer thereon.

[Prior art and problems to be solved by the invention] Conventionally, methods for manufacturing thin films of dyes, etc. include vacuum evaporation, thermal CVD, plasma CVD, and ultra-high vacuum (ion beam, molecular beam epitaxy) methods. .

The LB film removal method and casting method are known.

However, since all of these methods require operations such as dissolving materials such as dyes in organic solvents or heating them, they have not been able to form thin films of hydrophobic substances that are sensitive to heat.

In addition, a method of forming thin films of various hydrophobic organic substances by the so-called cell electrolysis method is also known (Electrochemical Association (Electrochemical Association)).
54th) Spring Conference F201) (1987). This ξ cell electrolysis method can efficiently produce thin films of various hydrophobic substances, and is attracting attention as an industrially advantageous method.

However, although the above ξ cell electrolysis method is an excellent method, it is necessary to introduce ferrocene as a redox group.
Synthesis of such a surfactant having a ferrocene group requires time and effort, and a simpler method is desired. Also,
According to the principle of cell electrolysis, a thin film can only be formed on the anode, so it has been extremely difficult to form a film on the aluminum electrode (cathode), which dissolves due to anodic polarization.

On the other hand, in the field of photosensitive materials, there is a desire to form films on aluminum substrates, and there are expectations for the development of a method that can easily form thin films on aluminum.

Under these circumstances, in recent years, hydrophobic substance powder with an average particle size of 10 μm or less has been used in an aqueous medium with an HLB value of 10.0 to 20.
．． A method has been proposed in which the above-mentioned hydrophobic substance thin film is formed on the cathode electrode by dispersing or solubilizing the hydrophobic substance with a surfactant (excluding ferrocene derivatives) of 0.0 and then applying an electric current to the obtained dispersion or solution. Chem, Lett.
, 1989. μm37).

However, the thin film formed by this method does not necessarily have sufficient uniformity, and even when used as a photoreceptor for electrophotography, the photosensitive characteristics are insufficient and it is not suitable for practical use.

Therefore, the present inventors conducted repeated experiments in detail regarding the above method.

[Means to solve the problem]

As a result, it has been found that by heating the electrolytic solution to a temperature of 40 to 8 degrees Celsius, the film forming properties, the uniformity of the formed thin film, and the characteristics of the photoreceptor are significantly improved.

The present invention was completed based on this knowledge. That is, the present invention disperses or solubilizes a hydrophobic substance powder with an average particle diameter of 0 μm or less in an aqueous medium with a surfactant (excluding ferrocene derivatives) having an HLB value of 10.0 to 20.0, and then 40% of the dispersion or solution
The present invention provides a method for producing a thin film, characterized in that a thin film of the hydrophobic substance is formed on a cathode by conduction treatment at a temperature of ~80''C.
HL of a hydrophobic charge-generating material powder of less than m in an aqueous medium.
It is dispersed or solubilized with a surfactant (excluding ferrocene derivatives) having a B value of 10.0 to 20.0, and then the resulting dispersion or solution is subjected to electrical treatment at 40 to 80"C to produce a product made of aluminum. The present invention also provides a method for manufacturing an electrophotographic photoreceptor, which comprises forming a charge generation layer of the charge generation material powder on a cathode.

In the thin film manufacturing method of the present invention, a hydrophobic substance powder is used as the material for the thin film. The average particle size of this hydrophobic substance powder is 0 μm or less, preferably about 1 to 0.01 μm. If the average particle size exceeds 10 μm, there are various problems such as it takes time to disperse and solubilize in an aqueous medium, and uniform dispersion and solubilization are difficult.

The type of hydrophobic substance powder mentioned above depends on the purpose of the thin film to be formed,
In particular, the material may be appropriately selected depending on the use as an electrophotographic photoreceptor, and various materials can be used, regardless of whether they are organic or inorganic materials. In the method for producing an electrophotographic photoreceptor of the present invention, the hydrophobic substance may be a charge generating substance (
Examples of organic substances include phthalocyanines, metal complexes of phthalocyanines and derivatives thereof (e.g. copper complexes, chloroaluminum complexes, vanadate complexes, chloroindium complexes, etc.), naphthalocyanines, Phthalocyanine metal complexes and their derivatives, porphyrins, porphyrin metal complexes and their derivatives, perylene, perylene metal complexes and their derivatives, azo dyes, quinacridones, viologens, and organic dyes such as photomemory dyes and sudans 5- electrochromic materials such as 1,1°-diheptyl-4.4°-bipyridinium dibromide, 1.1'-didodecyl 4.4°-bipyridinium dibromide, 6-nitro-1,3°3-trimethyl spiro- (2'H-1'-benzobyran-2,2''-indoline) (commonly known as spiropyran) and other photosensitive materials (photoblack ivy materials) and optical sensor materials, 1-phenylazo-2
- Diazo type photosensitive materials such as naphthol can be mentioned.

Furthermore, examples of inorganic substances include TiOz, C, and CdS.

W○31 F ego 3+ y203+ ZrO21
Ah O31Cu S .

There are various materials such as ZnS, Te0z, LiNbO3, 5izN4, and various superconducting oxides.

Next, the aqueous medium used in the present invention includes water,
Various media can be used, such as a mixture of water and alcohol and a mixture of water and acetone.

On the other hand, in the method of the present invention, a surfactant having an HLB (alO,o ~20.0, preferably 12 to 18) is used as a surfactant, excluding ferrocene derivatives. Examples include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkyl phenyl ether, and polyoxyethylene polyoxypropylene alkyl ether.In addition, alkyl sulfates, It is also possible to use polyoxyethylene alkyl ether sulfates, alkyltrimethylammonium chlorides, fatty acid diethylaminoethylamides, and the like.

In the method of the present invention, first, the above-mentioned surfactant and hydrophobic substance powder are placed in an aqueous medium and subjected to ultrasonic waves.

Stir thoroughly using a homogenizer or a stirrer for about 1 hour to 7 days. In this operation, the hydrophobic substance powder is uniformly dispersed or solubilized in the aqueous medium by the action of the surfactant having an HLB value of 10.0 to 20.0, and becomes a dispersion or an aqueous solution.

In the method of the present invention, a supporting salt is added to the homogeneous dispersion or aqueous solution obtained in this way, if desired, and excess hydrophobic substances are removed depending on the situation by centrifugation, decantation, static sedimentation, etc. The electrolyte solution obtained is removed by energization treatment while being left standing or with slight stirring. During this energization process, the electrolytic solution (
It is necessary to heat the above dispersion or aqueous solution to a temperature of 40 to 80°C, preferably 50 to 70°C, and more preferably 55 to 65°C. By carrying out the energization treatment at a temperature within this range, the resulting thin film can be formed uniformly and its photosensitivity properties can be improved.

Note that during the energization process, hydrophobic substance powder may be added to the electrolytic solution, or a portion of the electrolytic solution may be extracted from the system.
A circulation circuit may also be provided in which a hydrophobic substance powder is added to the electrolytic solution that has been extracted, the electrolyte is thoroughly mixed and stirred, and then this solution is returned to the system.

The concentration of the surfactant at this time is not particularly limited, but is usually 10 uM to 0.0 μM. IM, preferably 0.5mM
Select in the range of ~5mM. Further, a supporting salt (supporting electrolyte) is added as necessary to adjust the electrical conductivity of the aqueous medium. The amount of the supporting salt to be added may be within a range that does not interfere with the precipitation of the hydrophobic substance that has been solubilized or dispersed, and is usually about 0 to 300 times the amount of the above-mentioned surfactant, preferably 10 to 200 times the amount of the surfactant. Use as a guideline for the degree of darkness. Although it is also possible to conduct current application without adding this supporting salt, in this case a highly pure thin film containing no supporting salt can be obtained. In addition, when using a supporting salt, the type of supporting salt is
There are no particular limitations as long as the electrical conductivity of the aqueous medium can be adjusted without hindering the progress of solubilization or precipitation of the hydrophobic substance onto the electrode.

Specifically, sulfates (lithium, potassium, and sodium) are commonly used as supporting salts.

salts of rubidium, aluminum, etc.), acetate salts (lithium, potassium, sodium, rubidium, etc.).

salts of beryllium, magnesium, calcium, strontium, barium, argonium, etc.).

Halide salts (salts of lithium, potassium, sodium, rubidium, calcium, magnesium, aluminum, etc.), water-soluble oxide salts (salts of lithium, potassium, sodium, rubidium, calcium, magnesium, aluminum, etc.) - 0 suitable.

On the other hand, the cathode electrode is preferably selected from various metals, particularly base metals, and an aluminum substrate is particularly suitable when manufacturing an electrophotographic photoreceptor. Various types of anode electrodes can be used, such as I
Suitable materials include TO (mixed oxide of indium oxide and tin oxide), platinum, gold, silver, grady carbon, conductive metal oxides, organic polymer conductors, and semiconductors such as crystalline silicon and amorphous silicon.

The energization conditions in the method of the present invention may be set under conditions such that a thin film of the hydrophobic substance is formed on the cathode such as an aluminum 4 substrate. The conditions under which a thin film of the hydrophobic substance is formed on the cathode are not limited to the conditions under which a thin film of the hydrophobic substance is formed only on the cathode, but are also the conditions under which a thin film of the hydrophobic substance is formed on both the cathode and the anode. It also includes. These conditions vary depending on the situation, but specifically, the liquid temperature is set to 40°C.
While maintaining the temperature at ~80[deg.] C., the energization process is performed at a constant potential or constant current for 1 minute to 2 hours.

In this constant potential energization process, the distance between the two poles is 0.5
~10. OV, preferably 2.0 to 5. Set to a potential of OV, and when conducting constant current current density, set the current density to 1 μA/c+fl to 100 mA/c+fl,
Preferably, it may be set in the range of 100 μA/crfl to 10 mA/aa.

It is also effective to subject the thin film obtained by the method of the present invention to post-treatments such as electrical cleaning, solvent cleaning, and baking at 100 to 300°C, if necessary.

In order to produce an electrophotographic photoreceptor according to the method of the present invention, the above-mentioned thin film may be formed as a charge generation layer on a cathode made of aluminum in particular. It is also effective to form a charge transport layer (CTL) on the layer. This charge transport layer may be formed by a bar code method, a spin code method, a ξ cell electrolysis method, or the like.

The materials for the charge transport layer used here include indoline quinoline, triphenylamine, bisazo, pyrazole, pyrazoline, oxadiazole, thiazole, imidazole, and hydrazone.

Examples include compounds such as triphenylmethane, carbazole, benzaldehyde, bistriphenylamine, and polyvinylcarbazole, or derivatives thereof, and blends of these compounds and derivatives with various polymers and copolymers.

Note that after forming the charge generation layer on the cathode made of aluminum and before forming the charge transport layer thereon,
If necessary, an adhesive layer may be interposed between both layers. This adhesive layer is composed of polyamide, nitrocellulose, casein, polyvinyl alcohol, etc.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Copper phthalocyanine (manufactured by Tokyo Kasei ■, average particle size 0.1 μm) as a hydrophobic substance and polyoxyethylene lauryl ether (Kao ■) as a surfactant were added to 250 cc of water.
Manufactured by Br1j35. HL B value 1.8.0
) and lithium bromide as supporting salt, 7mM each.
, 2mM and 0.1M. This mixed solution was dispersed with ultrasonic waves for 30 minutes, and then stirred at room temperature all day and night.

Furthermore, after being allowed to stand overnight, 50 cc of the supernatant liquid was put into an electrolytic cell to serve as an electrolytic solution, and the temperature of the cell was set to 40° C. in advance. This cell was then fitted with an aluminum plate as a cathode,
A platinum plate was inserted as an anode, and constant current electrolysis was performed. At this time, the current density between the two electrodes was 0.2 mA/afl, and the amount of current was 0.2 C/c+It.

Examples 2 to 5 In Example 1, the cell temperature was set to 50"C and 6"C, respectively.
The same operation as in Example 1 was performed except that the temperatures were 0°C, 70'C, and 80°C. The results are shown in Table 1.

Comparative Examples 1 to 3 In Example 1, the cell temperature was set to 20"C and 3"C, respectively.
The same operation as in Example 1 was performed except that the temperature was 0°C and 190°C. The results are shown in Table 1.

3 4 Example 6 The thin film (charge generation layer: CGL-) formed in Example 1 was thoroughly washed with ethanol, dried, and a chlorobenzene solution of polyvinylcarbazole (concentration μm weight %) was placed on top of it.
) was spin-coded and a charge transport layer (C
TL) was formed. In this way, a photoreceptor consisting of polyvinylcarbazole CTL/copper phthalocyanine CGL/aluminum electrode was obtained.

The performance of this photoreceptor was evaluated using a 5P42B tester manufactured by Kawaguchi Electric as described below.

That is, the photoreceptor was subjected to corona discharge at -7 kV for 30 seconds to negatively charge the surface of the photoreceptor.

The surface potential at this time is Vd, and this Vd is the wavelength of 610
Irradiate with nm or 630 nm light (output 5 μW) and find the time (seconds) it takes to reach half the value (1/2 Vd),
Amount of light during that time (light intensity x time, unit: pJ/crl+)
was used as an index of the photoreceptor for light with a wavelength of 610 nm or 630 nm. The results are shown in Table 2.

5 6 Examples 7 to 10 and Comparative Examples 4 to 6 As CGL, Examples 2 to 5. The same operation as in Example 6 was performed except that the thin films formed in Comparative Examples 1 to 3 were used. The results are shown in Table 2.

(The following is a blank space) 7 [Effects of the Invention] As described above, according to the method of the present invention, a highly uniform thin film is formed, and if this thin film is used as a charge generation layer of an electrophotographic photoreceptor, it can be used to generate electrons with good sensitivity. A photographic photoreceptor is obtained.

The electrophotographic photoreceptor manufactured in this way has good sensitivity, that is, it has improved photoreceptor characteristics, so it can be used as a copier to copy clearer images, and the improved sensitivity reduces copying time and exposure It is possible to save energy on the light source. Therefore, printing time can be shortened in laser printers as well.

It becomes possible to save energy in the exposure light source.

Therefore, the electrophotographic photoreceptor manufactured by the method of the present invention can be used in copiers, laser printers, and other electronic device elements (EL, sensors, etc.) that use aluminum as an electrode.
Widely effective for solar cells, EC, LCD displays, FDP display display electrodes), elements using functional thin films (optical memory disks, PHB elements, superconducting elements, second-order nonlinear optical elements, third-order nonlinear optical elements), etc. used.

9-

Claims (4)

[Claims] (1) Hydrophobic substance powder with an average particle diameter of 10 μm or less is dispersed or solubilized in an aqueous medium with a surfactant (excluding ferrocene derivatives) having an HLB value of 10.0 to 20.0, and then the resulting dispersion is obtained. Alternatively, a method for producing a thin film, comprising subjecting the solution to an electric current treatment at 40 to 80° C. to form a thin film of the hydrophobic substance on the cathode. (2) The method for producing a thin film according to claim 1, wherein the cathode is a base metal. (3) Hydrophobic charge-generating material powder with an average particle size of 10 μm or less is dispersed or solubilized in an aqueous medium with a surfactant (excluding ferrocene derivatives) having an HLB value of 10.0 to 20.0, and then the obtained 40% of the dispersion or solution
A method for manufacturing an electrophotographic photoreceptor, comprising forming a charge generation layer of the charge generation substance powder on a cathode made of aluminum by conducting a current treatment at a temperature of 80°C to 80°C. (4) An electrophotographic photoreceptor characterized in that after forming a charge generation layer of the charge generation substance powder on the cathode made of aluminum by the method according to claim 3, a charge transport layer is formed on the charge generation layer. manufacturing method.