JPS59166958A - Manufacture of coated material - Google Patents

Abstract

PURPOSE:To form a transparent coating film in high reproducibility and to render the once opacified film again transparent by dipping the material to be coated into a film forming soln. and taking it up to remove most of the solvent of said soln. and then, bringing it into contact with the vapor of the solvent. CONSTITUTION:The material 3 to be coated, such the drum or the aluminum plate of an electrophotographic sensitive body, is dipped into a film forming soln., and pulled up at a constant speed to form a uniform film. The coated material is suspended in the air for about 30min to evaporate about 95% of the solvent. The material 3 is suspended in the vessel 1 in which the used solvent 2 or the film forming soln. is placed on the bottom to bring it into contact with the satd. vapor of the solvent. After 10min, it is dried at 70 deg.C for 1hr. As a result, a transparent film is formed with high reproducibility, and the once opacified film is made transparent again.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a coated article having a uniform and smooth coating film, and particularly to a method for producing a coated article, such as an electrophotographic photoreceptor drum on which a photosensitive layer and/or a protective layer have been formed, by applying the coating solution to the coated article. A coating method in which the liquid is moved upward relative to the liquid level and taken out of the liquid to form a liquid film on the surface of the object to be coated, and then the liquid film is dried and solidified to form a coating. This method is well known as the "immersion method."

The application of this immersion method to a method for manufacturing electrophotographic photoreceptors is disclosed in Japanese Patent Application Laid-open Nos. 49-130736 and 5
This method has been proposed in Japanese Patent Application Laid-open No. 0-26, Japanese Patent Laid-Open No. 50-75041, and is well known.

Among them, the invention described in JP-A-49-130736 and JP-A-50-75041 relates to a method of pulling up an object to be coated from a film-forming solution at a constant speed; The invention described in the publication relates to a method for lowering the liquid level of a film forming solution in which an object to be coated is immersed.

Both dipping methods include brush coating and roller coating.

Compared to the spray method, it is possible to form a smooth film on the surface of the object with a relatively simple operation.

However, when these immersion methods are used, the film formed is easily affected by the atmosphere during drying, and the film becomes significantly opaque especially in a high humidity atmosphere, especially when applied to an electrophotographic photoreceptor drum. There was a problem in that the electrophotographic properties, especially the sensitivity, deteriorated.

The reason why the film becomes opaque is that during the process of drying and solidifying the liquid film, moisture in the atmosphere condenses due to the heat of evaporation of the highly volatile solvent and is incorporated into the surface of the film that is being formed.

Conventional technology prevents the film from becoming opaque by controlling the atmosphere to low humidity, but
There were large variations in sensitivity and electrophotographic properties.

Furthermore, it was not possible to regenerate the film to be transparent once it had become opaque.

The present invention solves these problems and relates to a method for producing a coated article that overcomes the above problems by providing a new processing step.

That is, in the present invention, after immersing the object to be coated in a film-forming solution, the object to be coated is taken out of the solution, a film is formed on the surface of the object to be coated, and the film is then dried. In the method for manufacturing a coated article, after the article to be coated is removed from the solution, the film formed on the article to be coated is brought into contact with the vapor of a highly volatile solvent that is a component of the solution. The present invention relates to a method for producing a coated article characterized by:

The film-forming solution used in the present invention can be any of those conventionally used in the dipping method, and can be applied to 1% of the photosensitive layer of the photosensitive drum used in electrophotography.

It is effective for forming conductive layers and protective layers. Such a film-forming solution is a low-viscosity solution containing a non-volatile component that can form a film and a highly volatile solvent that can dissolve the component. Nonvolatile components include organic photoconductive materials, sensitizers, and resins, used alone or in combination.

Specific examples of organic photoconductive materials include:

Oxazolethiazole, oxadiazole.

Thiadiazole, triazole, imidacilone.

Various derivatives such as pyrazoline, polyvinylcarbazole or charge transfer complexes of polyvinylcarbazole and 2,4°7-trinitrofluorenone.

Examples include aromatic amine compounds and phthalocyanine pigments.

Sensitizers include triarylmethane dyes, xanthine dyes, thiazine dyes, and acridine dyes.

These include most common dyes such as quinoline dyes, ketone dyes, and cyanine dyes, and Lewis acids such as acids, acid anhydrides, metal halides, quinones, and ketones. The resins include polyester resin, acrylic resin, polycarbonate, polyvinyl formal, polyvinyl chloride, polystyrene, and the like.

Examples of highly volatile solvents include halogenated hydrocarbons such as dichloromethane, dichloroethylene, and trichloroethane; alcohols such as methanol, ethanol, and butanol;
Ketones such as acetone and methyl ethyl ketone, and ethyl ether.

Examples include ethers such as isopropyl ether, aromatic hydrocarbons such as toluene and xylene, solvents such as tetrahydrol, dimethylformamide, etc.

The film-forming solution consisting of the above components has a temperature of 0.5 to 50 C.
I) It is preferable to be in the range of S.

The object to be coated of the present invention is a photosensitive drum for electrophotography.

There are metal plates such as aluminum, etc., and the present invention is particularly suitably applied to those on which thin films are formed.

In the present invention, after the object to be coated is immersed in a film-forming solution, the object to be coated is taken out from the solution and a film is formed on the surface of the object to be coated.

The object to be coated may be immersed in a film-forming solution contained in a predetermined container, then pulled up, the solution discharged from the bottom of the container after immersion, or a combination of these methods. This is preferably carried out by moving the film-forming solution upwards relative to the liquid level.

The speed during the above movement is preferably in the range of 0.05 to 50 km/sec.

In order to form a uniform and smooth coating, the above movement is performed at a constant speed.

In addition, in the above, for the purpose of discharging the solution, a metering pump,
Although a siphon or the like can be used, there are no particular limitations on the discharge method.

In the present invention, the object to be coated is removed from the film-forming solution, and after the tackiness of the film formed on the object has disappeared, it is brought into contact with the vapor of a highly volatile solvent.

Remove the object to be coated from the film-forming solution and leave it at room temperature (approximately 20°C).
), the adhesiveness of the film disappears in 20 minutes to several hours. At this time, approximately 95% of the solvent in the film has evaporated. After this, the coating is applied within 3 hours, particularly preferably within 30 minutes. If too much time passes, the residual rate of the solvent will be too low, making it difficult to obtain a dry film with high smoothness.

The vapor pressure of the highly volatile solvent is preferably 5.
0 to 300 alHg, particularly preferably c.

150 to 300 mlHg is preferable. 300fiHg
The above amount may be used, but the amount of solvent used is small. Also.

It is preferable to use the saturated vapor pressure of each volatile solvent.

The preferred contact time is 1 to 10 minutes.

The temperature at this time is preferably 5 to 40°C2, particularly 15 to 30°C. As the temperature rises, drying progresses.

It becomes difficult to obtain smoothness of the coating film, and if 9 hours is too long, the coating film is likely to be re-dissolved.

After this, the film is heated to 40 to 120℃ for 1 minute to 1 minute.
Heat and dry for 2 hours.

The method of contacting the steam described above will be explained using the drawings. 1st
The figure is a schematic diagram showing an example of an apparatus for bringing a film formed on an object into contact with steam.

In FIG. 1, a highly volatile solvent or film-forming solution 2 is contained in a lower portion of a container 1. It is preferable to wet the wall surface inside the container 1 with the above-mentioned solvent or solution. As a result, the container 1 is filled with highly volatile solvent. In this state, the object to be coated 3 on which the film has been formed is housed in the container 1 so as not to come into contact with the solvent-sprayed solution 2 . Object to be coated 3
is held by a holder 4. Also.

Preferably, the upper surface of the container 1 is covered by covers 5 and 6.

In the present invention, FIG. 2 shows how a uniform and smooth film is formed by bringing the film formed on the surface of the object to be coated into contact with the vapor of a highly volatile solvent. (A) in FIG. 2 shows the coating 2 formed on the object 0 to be coated, and shows how water in the air has been incorporated into the coating surface. next,
(b) indicates that the water has partially evaporated, and (・→ indicates that the moisture has evaporated and the coating surface has lost its smoothness. If the coating is heated and dried in this state, the formed coating will naturally become smooth. However, as in the present invention, when the coating is brought into contact with the vapor of a highly volatile solvent, it becomes a smooth coating without moisture as shown in ()→.

Next, an example of the present invention will be shown.

Example 1 Outer diameter 120gIan, inner diameter 112mm, length 300 (roll)
An aluminum drum was immersed in the following photosensitive layer forming solution and then pulled up at a speed of 51 B/sec to form a liquid film on the drum surface. After being left at room temperature for 5 minutes, the surface of the liquid film lost its tackiness and a film was being formed. The surface of this coating was opaque. Next.

Fill the drum with 2000C of tetrahydrofuran.

Cylindrical container (inner diameter 160 dew,
The specimen was placed at a height of 400 W for 2 minutes as shown in FIG. This resulted in a transparent coating. Thereafter, the drum was taken out, left at room temperature for 10 minutes, and then dried and solidified at 70°C for 1 hour. - (Composition of photosensitive layer forming solution) Poly-N-vinylcarbazole 6 Weight ratio 2.4.
7-) Rinitrofluorenone 2.4 Tetrahydro 7
Run 91 〃Example 2 Vertical 10 Qam, Width 70 rtm, Thickness o, s rtrm
A coating was formed on a ram board in the same manner as in the example to produce a coated product.

The coating was transparent. The coated object was charged at +6KV for 10 minutes using an electrostatic recording paper measuring device 5P-428 manufactured by Kawaguchi Electric.
Table 1 shows the results of determining the electrophotographic characteristics by measuring potential changes under condition K (dynamic measurement) of exposing the sample to white light at 10 tx 5 seconds after the end of charging.

Comparative Example After forming a liquid film on the aluminum plate in Example 2 5
The mixture was left to stand for a minute and then immediately dried and solidified at 70'C for 1 hour. The coating was opaque. The electrophotographic properties measured in the same manner as in Example 2 are shown in Table IK.

Table 1 Electrophotographic characteristics Thickness of film: 10 μm Note 1) Surface potential after 10 seconds at -6 fv charging 2) Ratio of surface potential 5 seconds after the end of charging to the initial potential Note 3) The potential attenuated by exposure becomes foggy Product of the time when the photoinitiation potential is reduced to 1 and the amount of white light exposure Note 4) Surface potential 60 seconds after the start of exposure The present invention makes it possible to produce coated objects with a transparent film with good reproducibility, and once it becomes opaque. It is also possible to produce coated objects by regenerating the film to make it transparent.

In particular, in an electrophotographic photosensitive drum on which a photosensitive layer and/or a protective layer is formed, the sensitivity in electrophotographic characteristics can be improved.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing an example of an apparatus for bringing a coated object on which a liquid film has been formed according to the present invention into contact with the vapor of a highly volatile solvent, and Figure 2 shows the process of film change in the present invention. FIG. Explanation of symbols 1... Container 2... Highly volatile solvent or film-forming solution 3... Object to be coated with a film 4... Support 5, 6... Cover 7...
Object to be coated 8... Film 9... Moisture agent Patent attorney Kunihiko Wakabayashi Figure 1

Claims (3)

[Claims] (1) After immersing the object to be coated in a film-forming solution. In a method for producing a coated article by removing the object to be coated from the solution, forming a film on the surface of the object and then drying the film, after removing the object to be coated from the solution, A method for producing a coated article, which comprises first bringing the film formed on the article into contact with the vapor of a highly volatile solvent that is a component of the solution. (2) The object to be coated is an electrophotographic photosensitive drum. 2. The method for producing a coated article according to claim 1, wherein the film-forming solution is a photosensitive layer-forming solution. (3) A method for producing a coated article described for electrophotography, in which the coated article has a photosensitive layer on its surface.