JP2003098698A - Method for dip coating of electrophotographic photoreceptor and electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for dip coating of a photographic photoreceptor capable of yielding a satisfactory coated film layer by limiting the specific gravity of a solvent used for a coating liquid, dipping an object to be coated in the coating liquid up to the upper end of the object, temporarily keeping the object in that state, eliminating a portion of air inside the object to be coated and subsequently pulling up the object. SOLUTION: In this method for applying a dip coating to an electrophotographic photoreceptor for dipping the object to be coated in the coating liquid and forming a coating film layer on the object to be coated, the specific gravity used for the coating liquid ranges between 0.780 and 1.200. The object to be coated is dipped in the coating liquid with air inside the object to be coated confined while the opening part of the object to be coated is turned down. When the object to be coated is dipped up to its highest end, the object is temporarily kept in that state, the air inside the object is also partially eliminated, and the object is subsequently pulled up to form a coating film layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dip coating method in which an article to be coated is dipped in a coating solution to form a coating layer, and an object thereof is to form a uniform coating layer without coating unevenness. And an electrophotographic photoreceptor (hereinafter, also simply referred to as a photoreceptor).

[0002]

2. Description of the Related Art A dip coating method is suitable as a method for forming a uniform coating layer on the outer peripheral surface of an object to be coated, and is widely used in the production of photoreceptors. In such a dip coating method, in order to grip an object to be coated, a rubber member (balloon chuck) capable of expanding and contracting a gripping member is inserted inside the object to be contracted, and then air is pressed into the rubber member. Then, it is usually performed that the product is inflated and brought into pressure contact with and closely adhered to the inner wall of the object to be coated, the object to be coated is gripped, dipped in the coating solution and applied. However, it is necessary to prevent the coating liquid from penetrating into the coating object from the lower end opening of the coating object and adhering to the inner peripheral surface of the coating object when the coating object is immersed in the coating liquid. was there.

For this reason, it has been practiced to fit the gripping device to the object to be coated in a hermetically sealed manner and to keep the lower part inside the object to be sealed in an airtight state except for the lower end opening.

On the other hand, as the solvent for the coating liquid, a solvent having a relatively low boiling point and high volatility is usually used. When the article to be coated is immersed in a coating solution prepared using such a highly volatile solvent, the solvent on the liquid surface at the lower end opening vaporizes, and the vaporized solvent vapor increases the gas volume inside the article to be coated. To do. When the gas volume inside the object to be coated increases during dip coating, the gas (air containing solvent) that has become larger than the lower end of the object to be coated jumps out into the coating liquid as bubbles. When the popped bubbles rise to the surface of the coating liquid along the outer peripheral surface of the object to be coated, the surface of the coating liquid is disturbed, uneven coating may occur in the formed coating layer, and the uniformity may be impaired.

In order to prevent the generation of such bubbles, a method (venting method) using a gripping mechanism having a function of adjusting the air pressure in the object to be coated is disclosed in JP-A-60-132678 and JP-A-60-255164. JP-A-63-3151
No. 67 publication.

However, although such a method could solve the generation of bubbles, it was not possible to prevent the generation of fine unevenness in the coating layer.

Conventionally, a halogen-based solvent having a large specific gravity has been used relatively frequently because it is a good solvent for polycarbonate which is a binder used in the charge transport layer. Due to its large specific gravity, the solvent vapor of the coating solution stagnates inside the object to be coated, causing uneven pressure inside the object to be coated, and the air pressure is not adjusted accurately, or the top of the coating solution is stagnant. The solvent vapor may cause fine unevenness in the coating layer.

Further, in recent years, it has been recommended to use a non-halogen solvent for environmental reasons.

[0009]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above problems, and limits the specific gravity of the solvent used in the coating liquid, and immerses the object to be coated in the coating liquid to the upper end to temporarily stop. At the same time, it is another object of the present invention to provide a dip coating method for a photoconductor in which a good coating layer can be obtained by pulling up a part of the air inside the article to be coated and then pulling it up.

[0010]

As a result of intensive studies on the above problems, the present inventors have found that there is a correlation between the weight of the solvent vapor, that is, the specific gravity of the solvent and the unevenness of the coating layer.

If the specific gravity of the solvent is large, the solvent vapor is stagnated at the upper part of the coating liquid, and the solvent vapor fluctuates, so that fine unevenness occurs in the coating layer. However, if the specific gravity is small, the solvent vapor is formed at the upper part of the coating liquid. It has been found that the stagnation is unlikely to occur and such a phenomenon is unlikely to occur.

Further, when a solvent having a small specific gravity is used, the difference in the vapor densities filling the inside of the object to be coated is small, so that the air pressure can be adjusted accurately, and there is no generation of bubbles or turbulence of the coating liquid surface during pulling up. It was also found that coating unevenness or fine unevenness of the coating layer does not occur.

That is, the object of the present invention can be achieved by adopting one of the following configurations. 1. In the dip coating method of the electrophotographic photosensitive member, which comprises immersing the article to be coated in a coating solution and forming a coating layer on the article to be coated,
The specific gravity of the solvent used for the coating liquid is 0.780 to 1.200.
And, with the opening of the article to be coated facing downward, the article to be coated is immersed in the coating solution in a state where air is contained inside the article to be coated, and when the immersion reaches the uppermost end, At the same time as stopping, part of the air inside the coating object is removed, and then
A dip coating method for an electrophotographic photoreceptor, which comprises pulling up to form a coating layer.

2. 2. The immersion coating method for an electrophotographic photosensitive member according to item 1, wherein a speed of pulling up the object to be coated is slower than a speed of immersing the object in the coating liquid.

3. The specific gravity of the solvent is 0.790 to 1.1
00 is the immersion coating method for an electrophotographic photosensitive member according to item 1 or 2 above.

4. An electrophotographic photosensitive member produced by the dip coating method for an electrophotographic photosensitive member according to any one of items 1 to 3.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic view of the steps in the dip coating method for the photoconductor of the present invention. The dip coating method for the photoconductor (hereinafter, also simply referred to as dip coating method) is as follows: A → B → C in FIG.
→ D → E process is performed.

FIG. 1A shows a state in which the object to be coated 2 is gripped by the gripping device 1 and is relatively close to the liquid surface of the coating liquid 4 while being gripped by the gripping device 1.

In the figure, 3 is a solvent vapor atmosphere, 5 is an air vent pipe, and 6 is a valve. B of FIG. 1 shows a state immediately after the object to be coated 2 starts to be dipped in the coating liquid 4.

In FIG. 1C, the article to be coated 2 is immersed in the coating solution 4 up to the upper end leaving the uncoated portion 7 and then temporarily stopped, and at the same time, the valve 6 of the air vent pipe 5 is opened and the article to be coated 2 is coated. Part of the air inside the chamber is replaced with coating liquid 4
The state where the coating liquid 4 is penetrated from the lower end to the penetration depth 8 is shown.

FIG. 1D shows a state in which the article 2 to be coated is being pulled up from the coating liquid 4 and the coating layer 9 is being formed on the outer peripheral surface of the article 2 to be coated.

FIG. 1E shows a state in which the article 2 to be coated is pulled up from the coating liquid 4 and the coating layer 9 is formed on the outer peripheral surface of the article 2 to be coated.

The gripping device grips the shaft of the object to be coated perpendicularly or almost perpendicularly to the liquid surface of the coating liquid 4, and while being immersed in the coating liquid, the coating liquid is kept inside the object to be coated. It is a chuck that functions to prevent entry.

The chuck is not particularly limited as long as it can vertically hold an object to be coated and can prevent the coating liquid from entering the inside of the object to be coated. Specifically,
A balloon chuck, an O-ring chuck, a mechanical chuck, etc. can be mentioned. Of these, a balloon chuck that is easy to use in combination with an air vent pipe and a gripping device is preferable.

The length of the uncoated portion varies depending on the electrophotographic apparatus in which the photoconductor thus prepared is loaded, but it is 0.0-2.
0 cm is preferred.

The pause time is preferably longer than 0 second and within 60 seconds, more preferably 1 to 30 seconds, further preferably 2 to 10 seconds. If the pause time is 0 seconds, the time for removing part of the air may not be in time for the application, and air bubbles may jump into the application liquid from the lower end of the object to be coated. If it is longer than 60 seconds, the time required for the application will be long. At the same time, there is a risk that the lower coating layer will be eluted into the coating liquid and the coating liquid will be contaminated.

The pulling rate varies depending on the viscosity of the intermediate layer, the charge generation layer, the charge transport layer, etc., the solid content concentration, the temperature, the required thickness of the coating layer, etc., but is 0.1 to 5.0 cm /
s is preferable, and 0.2 to 3.0 cm / s is more preferable. The immersion speed is preferably 1.1 to 20 times faster than the pulling speed, and more preferably 1.2 to 10 times faster. If it is less than 1.1 times, it will be disadvantageous because it takes time in the process, and if it exceeds 20 times, the liquid surface will be disturbed at the time of dipping and unevenness of the coating layer will be likely to occur.

The amount of air to be evacuated depends on the temperature and viscosity of the coating liquid, the temperature of the object to be coated, the size and heat capacity of the object to be coated, and is 0.5 to 5.0 c based on the lower end of the object to be coated.
The amount is preferably such that the coating liquid penetrates into the object to be coated up to m. If the depth of penetration of the coating liquid is less than 0.5 cm, it is not possible to deal with shaking and vibration of the liquid, and bubbles easily pop out into the coating liquid. Shaking is large and uneven coating is likely to occur.

The timing of bleeding the internal air preferably starts at the same time as the temporary stop and is completed within the temporary stop time.

Specifically, it can be performed by controlling the timing and time for opening and closing the valve 6 of the air vent pipe 5 that penetrates the gripping device 1 shown in FIG.

Next, the material according to the present invention will be described. The coating solvent according to the present invention has a specific gravity (20 ° C.) of 0.780 to 1.200,
It is more preferably 90 to 1.100.

Specifically, chlorobenzene (specific gravity 1.1)
06), 1,4-dioxane (specific gravity 1.039), toluene (specific gravity 0.866), methyl ethyl ketone (specific gravity 0.805), tetrahydrofuran (specific gravity 0.88).
9), cyclohexanone (specific gravity 0.945), 1,3-
Dioxolane (specific gravity 1.065), ethylene glycol dimethyl ether (specific gravity 0.867), t-butyl acetate (specific gravity 0.867), 2-methoxy-2-methyl-4-
Pentanone (specific gravity 0.910), n-butanol (specific gravity 0.810), isopropyl alcohol (specific gravity 0.78)
5), ethanol (specific gravity 0.791), methanol (specific gravity 0.792) and the like, but not limited thereto.

Here, the coating solvent means a coating composition from which solid components and additives have been removed.

When the specific gravity of the coating solvent exceeds 1.200,
A solvent vapor atmosphere layer with a high specific gravity drifts on the surface of the coating liquid, and it is easy to cause fine step unevenness in the lifted coating layer.
If it is less than 8, it is difficult to keep the viscosity of the coating solution constant because the solvent is likely to vaporize from the surface of the coating solution.

The specific gravity of the coating solvent is "JIS Z-8804".
It can be measured by the measuring method of "1994".

The material to be coated according to the present invention includes:
The following may be mentioned, but the present invention is not limited thereto.

1) A conductive metal material such as aluminum or stainless steel 2) A material in which a thin conductive metal layer such as aluminum, palladium and gold is laminated or vapor-deposited on paper or plastic 3) Paper or plastic On top of the conductive polymer,
A material obtained by applying or depositing a layer of a conductive compound such as indium oxide and tin oxide.

Among these, the conductive metal of aluminum is preferably used. As the shape of the object to be coated, a cylindrical substrate capable of forming an image endlessly by rotating is preferable. The thickness, diameter and length of the cylindrical substrate are not particularly limited and can be arbitrarily determined depending on the electrophotographic image forming apparatus used. The straightness of the cylindrical substrate is preferably 0.10 mm or less and the deflection is preferably 0.10 mm or less. If the circularity and the shake range are exceeded, good image formation becomes difficult.

The photoconductor according to the present invention will be described below. The photoreceptor is, for example, one in which a charge generation layer and a charge transport layer are sequentially laminated on an object to be coated, or an intermediate layer, a charge generation layer, and a charge transport layer are sequentially laminated on the object to be coated. Examples thereof include, but are not limited to, those obtained by further laminating a surface layer on the charge transport layer.

The layer structure of the photoconductor will be specifically described. << Intermediate Layer >> The intermediate layer is provided between the article to be coated and the photosensitive layer in order to improve the adhesion between the article to be coated and the photosensitive layer to be described later or to prevent charge injection from the article.

Examples of the material of the intermediate layer include, but are not limited to, polyamide resin, vinyl chloride resin, vinyl acetate resin, and copolymer resin containing two or more of the repeating units of these resins. It is not something that will be done. Among these resins for the intermediate layer, a polyamide resin can be mentioned as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.1 to 5.0 μm.

Other preferably used intermediate layers include, for example, an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent and a titanium oxide coupling agent. The thickness of the intermediate layer using the curable metal resin is preferably 0.05 to 2 μm.

The intermediate layer is produced by coating a coating solution for the intermediate layer prepared by dissolving the above resin with a coating solvent on the object to be coated by the dip coating method of the present invention and drying it. Preferably.

The coating solvent is not particularly limited as long as it dissolves the above resin and has a specific gravity (20 ° C.) of 0.780 to 1.200. For example, methanol, ethanol, methyl ethyl ketone, toluene or the like can be used. preferable.

<< Photosensitive Layer >> The photosensitive layer may have a single-layer photosensitive layer structure in which one layer has a charge generating function and a charge transporting function on the intermediate layer, but the photosensitive layer function is more preferable. It is preferable to separate the charge generation layer and the charge transport layer from each other. By adopting a constitution in which the functions are separated, the increase in residual potential due to repeated use can be controlled small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negative charging photoreceptor, it is preferable to have a charge generation layer on the intermediate layer and a charge transport layer on the intermediate layer. In the case of the photoconductor for positive charging, the order of the layers is the reverse of that of the photoconductor for negative charging.

If necessary, a surface layer can be provided on the charge transport layer. The surface layer has hardness and improves the abrasion resistance of the photoconductor, and is used by being provided on the uppermost layer of the photoconductive layer.

The constitution of the photosensitive layer of the function-separated negatively charged photoreceptor and the method for producing it will be described below. <Charge Generation Layer> The charge generation layer contains a charge generation substance. If necessary, binder resin,
Other additives may be included.

As the charge generating substance, known charge generating substances can be used. Specific examples thereof include phthalocyanine pigments, azo pigments, perylene pigments, and azurenium pigments, but are not limited thereto. Among them, the one that can minimize the increase in residual potential due to repeated use is one having a steric and potential structure capable of forming a stable aggregation structure among a plurality of molecules, and specifically, a phthalocyanine having a specific crystal structure. Examples include charge generating substances such as pigments and perylene pigments. For example Cu-K
C such as titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to α rays and benzimidazole perylene having a maximum peak at 22.4 of the same 2θ.
The GM hardly deteriorates with repeated use, and the increase in residual potential can be reduced.

When a binder is used as the dispersion medium of the charge generating substance in the charge generating layer, a known resin can be used as the binder, and as a specific example, formal resin,
Examples thereof include butyral resin, silicone resin, silicone-modified butyral resin, and phenoxy resin, but are not limited thereto. The ratio of the binder resin to the charge generating substance is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the resin. By using these resins, the increase in residual potential due to repeated use can be minimized. The thickness of the charge generation layer is preferably 0.1 to 2.0 μm.

For the charge generation layer, a charge generation layer coating solution prepared by dispersing a charge generation substance together with a binder resin and other additives in a coating solvent is applied onto the intermediate layer by the dip coating method of the present invention. It is preferable to apply a uniform film thickness and dry it to prepare.

The coating solvent is not particularly limited as long as it dissolves the resin and has a specific gravity (20 ° C.) of 0.780 to 1.200, and examples thereof include methanol, ethanol, methyl ethyl ketone, toluene and t-butyl acetate. And 2-
It is preferable to use methoxy-2-methyl-4-pentanone or the like.

As a means for dispersing the charge generating substance in the coating liquid, for example, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer and the like can be used, but the means is not limited to these.

<Charge Transport Layer> The charge transport layer contains a charge transport material. If necessary, a binder resin and other additives may be contained as other substances.

As the charge transport material, known materials can be used. Specifically, a triphenylamine derivative,
Examples thereof include hydrazone compounds, styryl compounds, benzidine compounds and butadiene compounds, but are not limited to these.

Known resins can be used as the binder, and specific examples thereof include polystyrene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin. , Alkyd resin, polycarbonate resin, silicone resin,
Examples thereof include, but are not limited to, a melamine resin and a copolymer resin containing two or more of repeating units of these resins. In addition to these insulating resins, polymer organic semiconductors such as poly-N-vinylcarbazole can be used. Preferred as a binder for these charge transport layers is a polycarbonate resin. Polycarbonate resin is preferable in terms of improving the dispersibility of the charge transport material and the electrophotographic characteristics.

The ratio of the binder resin to the charge transport material is 1 charge transport material to 100 parts by weight of the binder resin.
0 to 200 parts by mass is preferable. The thickness of the charge transport layer is 1
0 to 30 μm is preferable.

For the charge transport layer, a charge transport layer coating solution prepared by dissolving a charge transport material, a binder resin, and other substances in a coating solvent is fixed on the charge generating layer by the dip coating method of the present invention. It is preferable to apply the film having the thickness of 1 and dry.

The coating solvent is not particularly limited as long as it dissolves the resin and has a specific gravity (20 ° C.) of 0.780 to 1.200, and examples thereof include methanol, ethanol, methyl ethyl ketone, toluene, cyclohexanone and tetrahydro. It is preferable to use furan or the like.

As a means for dissolving the charge transport substance in the coating liquid, for example, an ultrasonic disperser, a ball mill, a homomixer and the like can be used, but the means is not limited to these.

All coating layers of photoreceptor (intermediate layer + charge generation layer +
It is preferable that the thickness of the charge transport layer) is approximately 10 to 37 μm.

Next, an image forming apparatus using a photoreceptor prepared by the dip coating method of the present invention will be described.

FIG. 2 is a sectional view showing an example of an electrophotographic image forming apparatus for forming an image by using a photoreceptor prepared by a dip coating method.

The electrophotographic image forming apparatus is an apparatus for forming an image by using a photosensitive drum and repeating charging, exposing, developing, transferring, separating and cleaning steps.

The electrophotographic image forming apparatus shown in FIG. 2 will be described below. Light is emitted from the semiconductor laser light source 21 based on information read by a document reading device (not shown). This is scanned by the polygon mirror 22 and is irradiated onto the surface of the photoconductor drum through the fθ lens 23 that corrects the distortion of the image, and an electrostatic latent image is formed by the digital exposure method. The photoconductor drum 24 is the charger 2 in advance.
It is uniformly charged by 5, and starts rotating clockwise in accordance with the timing of light irradiation.

The electrostatic latent image on the surface of the photosensitive drum is the developing device 2
Inverse development is performed by 6 to form a toner image. The formed toner image is transferred by the action of the transfer device 27 to the transfer body 28 that has been conveyed at the same timing. Further, the photosensitive drum 24 and the transfer body 28 are separated by a separator (separation pole) 2
Although separated by 9, the toner image is transferred and carried by the transfer member 28, guided to the fixing device 30, and fixed to form a print image.

Thereafter, the photosensitive drum 24 is cleaned of untransferred toner and the like remaining on the surface of the photosensitive drum by a cleaning device 31 of a cleaning blade type, and precharge exposure (PCL) 32 removes residual charges. , The next image is uniformly charged by the charger 25 again.

The transfer body 28 is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and includes a PET base for OHP and the like.

The cleaning blade 33 has a thickness of 1
A rubber-like elastic body of about 30 mm is used, and urethane rubber is often used as the material.

[0070]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 <Subject to be coated> Thickness of 0.2 m obtained by drawing
Cylindrical aluminum with m, a diameter of 8 cm, and a length of 40 cm was used as “application target 1”.

<Preparation of Coating Liquid for Intermediate Layer> Polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) 10 g Titanium oxide “SMT500SAS” (manufactured by Teika Co., Ltd.) 30 g Methanol 200 g The above materials for the intermediate layer are processed by a sand mill disperser for 10 hours. After the dispersion, the mixture was allowed to stand overnight and filtered (filter: “Rigimesh filter” manufactured by Nippon Pall Co., Ltd., nominal filtration accuracy 5 μm,
The pressure was 5 × 10 ⁴ N / m ² ) to prepare “Coating Liquid 1 for Intermediate Layer”.

<Coating of Intermediate Layer> “Subject 1 to be coated” is applied to the above “coating liquid 1 for intermediate layer” at a speed of 2 cm / s under the conditions of room temperature and liquid temperature of 25 ° C. Was soaked up to 1 cm. Then stop for 10 seconds,
The depth of penetration of "Intermediate layer coating liquid 1" into the object to be coated is 1
The valve of the pipe was opened so as to be cm, and air was released.
After that, the object to be coated is pulled up at a speed of 1.2 cm / s,
It was dried to prepare “Intermediate layer 1” having a dry film thickness of 2 μm.

When the "intermediate layer 1" was visually observed, it was confirmed that there was no coating unevenness due to bubbles jumping out from the inside of the object to be coated and fine stepwise unevenness due to the stagnation of solvent vapor.

Example 2 <Preparation of Coating Liquid for Charge Generation Layer> Titanyl phthalocyanine 20 g Butyral resin “# 6000-C” (manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 g t-butyl acetate 700 g 2-methoxy-2-methyl -4-Pentanone 300 g The above charge generation layer material was dispersed by a sand mill disperser for 10 hours to prepare "charge generation layer coating liquid 1".

<Coating of charge generation layer>
At room temperature and a liquid temperature of 25 ° C., it was immersed in the “charge generation layer coating liquid 1” at a rate of 2 cm / s until the uncoated portion of the coated object became 0.7 cm. After that, the liquid was stopped for 8 seconds, and at the same time, about 1 cm of air into which the “charge generation layer coating liquid 1” entered the inside of the coating object was removed from the inside of the coating object by opening the valve. After that, the object to be coated was pulled up at a speed of 1.3 cm / s and dried to prepare a “charge generation layer 1” having a dry film thickness of 1 μm.

When the "charge generation layer 1" was visually observed, it was confirmed that there was no coating unevenness due to bubbles jumping out from the inside of the object to be coated and fine stepwise unevenness due to stagnation of solvent vapor.

Example 3 <Preparation of Coating Liquid for Charge Transport Layer> Charge transport material “S-1” 75 g Polycarbonate resin “Iupilon Z300” 100 g (manufactured by Mitsubishi Gas Chemical Co., Inc.) Tetrahydrofuran 700 g Cyclohexanone 50 g The above charges The material for the transport layer was dissolved to prepare "Coating liquid 1 for charge transport layer".

<Coating of charge transport layer>
At room temperature and a liquid temperature of 25 ° C., it was immersed in the “charge transport layer coating liquid 1” at a rate of 1 cm / s until the uncoated portion of the coated object became 0.5 cm. Thereafter, the operation was stopped for 10 seconds, and at the same time, an amount of air in which the “charge transport layer coating liquid 1” was introduced into the article to be coated by about 0.5 cm was removed from the article to be coated by opening the valve. After that, the coated object is 0.2 cm /
It was pulled up at a speed of s and dried to prepare a “charge transport layer 1” having a dry film thickness of 25 μm.

When the "charge transport layer 1" was visually observed, it was confirmed that there was no coating unevenness due to bubbles jumping out from the inside of the object to be coated and fine stepwise unevenness due to stagnation of solvent vapor.

Example 4 The “charge generating layer 1” is provided on the “intermediate layer 1” produced in Example 1 in the same manner as in Example 2, and further thereon, in the same manner as in Example 3. A "photoreceptor 1" was prepared by providing the "charge transport layer 1".

The above-mentioned "photoreceptor 1" is replaced with a digital copying machine "Ko".
nica7140 ”(manufactured by Konica Corporation) and printed. When the printed image was visually evaluated, a good image without coating unevenness and fine stepwise unevenness was obtained.

Comparative Example 1 Application was carried out in the same manner as in Example 3 except that air was not pulled out from the inside of the object to be coated, but the "charge transport layer 2" was formed. It was made.

When the "charge transport layer 2" was visually observed, coating unevenness due to bubbles jumping out from the inside of the object to be coated was confirmed.

Comparative Example 2 In Example 3, the same amount of methylene chloride was used in place of the solvent, tetrahydrofuran / cyclohexanone, used in the preparation of “Coating liquid 1 for charge transport layer”. Liquid 2 "was prepared. This "Charge Transport Layer Coating Liquid 2" was applied in the same manner as in Example 3 and dried to prepare "Charge Transport Layer 3".

When the "charge transport layer 3" was visually observed, fine stepwise unevenness due to the stagnation of the solvent vapor was confirmed.

Comparative Example 3 A "charge generation layer 1" was provided on the "intermediate layer 1" prepared in Example 1 in the same manner as in Example 2, and the same procedure as in Comparative Example 1 was performed thereon. Then, "charge transport layer 2" was provided to prepare "photoreceptor 2".

The above "photoreceptor 2" is replaced with a digital copying machine "Ko".
nica7140 ”(manufactured by Konica Corporation) and printed. When the printed image was visually evaluated, it was found to be unusable for practical use due to image defects caused by uneven coating.

Comparative Example 4 A "charge generation layer 1" was provided on the "intermediate layer 1" produced in Example 1 in the same manner as in Example 2, and further thereon in the same manner as in Comparative Example 2. A "photoreceptor 3" was prepared by providing the "charge transport layer 3".

The above "photoreceptor 3" is replaced with a digital copying machine "Ko".
nica7140 ”(manufactured by Konica Corporation) and printed. When the printed image was visually evaluated, it was found to be unusable for practical use due to image defects caused by fine stepwise unevenness.

<< Evaluation >> [Examples 1 to 1 produced as described above]
In "3", a good coating layer having no unevenness was obtained, but in "Comparative Examples 1 and 2", a coating layer having coating unevenness or fine unevenness was obtained.

The image printed using the photoconductor prepared in "Example 4" was a good image without unevenness, but the photoconductor prepared in "Comparative Examples 3 and 4" was used. The printed image had coating unevenness or fine step unevenness and was unusable for practical use.

[0093]

According to the dip coating method for a photoreceptor of the present invention, the specific gravity of the solvent used in the coating solution is limited, and the article to be coated is dipped in the coating solution to the upper end thereof to be temporarily stopped and to be coated. It has an excellent effect that a good coating layer can be obtained by pulling up after removing a part of the internal air.

[Brief description of drawings]

FIG. 1 is a schematic view of steps in a dip coating method for a photoreceptor of the present invention.

FIG. 2 is a cross-sectional view showing an example of an electrophotographic image forming apparatus that forms an image using a photoreceptor prepared by a dip coating method.

[Explanation of symbols]

1 gripping device 2 Object to be coated 3 solvent vapor atmosphere 4 coating liquid 5 Air vent pipe 6 valves 7 Unapplied part 8 penetration depth 9 Coating layer

Claims (4)

[Claims] 1. In a dip coating method for an electrophotographic photoreceptor, which comprises immersing an article to be coated in a coating solution to form a coating layer on the article to be coated, the specific gravity of a solvent used in the coating solution is 0.780. ~
1.200, the opening of the article to be coated was faced down, and the article to be coated was immersed in the coating solution in a state where air was contained inside the article to be coated, and the immersion reached the uppermost end. At this time, while temporarily stopping, a part of the air inside the article to be coated is evacuated and then pulled up to form a coating layer, which is a dip coating method for an electrophotographic photoreceptor. 2. The dip coating method for an electrophotographic photosensitive member according to claim 1, wherein the pulling speed is slower than the dipping speed of the object to be coated in the coating liquid. 3. The specific gravity of the solvent is 0.790 to 1.10.
It is 0, The immersion coating method of the electrophotographic photosensitive member of Claim 1 or 2 characterized by the above-mentioned. 4. An electrophotographic photosensitive member produced by the dip coating method for an electrophotographic photosensitive member according to claim 1.