JPS61223843A - Formation of thin film - Google Patents

Abstract

PURPOSE:To easily form an extremely uniform thin film, by removing liquid puddles which occur after the liquid is applied to the surface of a supporting body by means of a sucking means. CONSTITUTION:After a cylindrical supporting body 1 is dipped in a liquid tank 8 under a condition where the hollow of the supporting body 1 is enclosed by means of a top and bottom lids 5 and 6, the supporting body 1 is brought up by its handle 7 and an applied film 2a is formed. After the supporting body 1 are removed by sucking by means of a sucking device 10 while the supporting body 10 is slowly rotated in the direction shown by the arrow G. The sucking power of this sucking operation is controlled by adjusting the water quantity by means of an opening/closing cook 13. Then the applied film 2a is dried with a hot blast.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a thin film on the surface of a support, and particularly relates to an improvement in a method for forming a thin film as a recording medium in fields such as electrophotography and electrostatic recording.

[Conventional technology]

Conventionally, there are a wide variety of techniques for forming various thin films on supports such as metal, plastic, wood, and paper depending on the purpose.

For example, methods such as spraying, brush coating, casting coating, and roller coating are used, but even though these methods may produce a thin film that appears macroscopically uniform, microscopically it is extremely uneven. Since it is uniform, it is not suitable for use as a thin film for recording, for example. For example, JP-A-49-130738 discloses a method of coating a cylindrical support by immersing it in a photosensitive liquid containing an organic photoconductor. For example, Japanese Patent Application Laid-Open No. 53-119042 discloses that after coating a cylindrical support by dipping it in a photosensitive liquid containing a photoconductor, in order to avoid the formation of a liquid pool at the trailing end of the coating, A technique for providing a taper as shown in FIG. 4 at the lower end of the support is disclosed.

Figure 4 is a cross-sectional view of a cylindrical support coated with a photosensitive liquid.
1 is a cylindrical conductive support, 2 is a photosensitive layer, and 3 is a taper. The support 1 is coated by dipping it into a container filled with a photosensitive liquid, and then pulled up above the drawing and dried.
It is said that a liquid pool generated below the support during pulling up can be removed by being stretched by the action of the surface tension of the surface of the taper 3.

In a copying machine or the like, both ends of the photoreceptor are placed outside the image forming area, and a roller or the like is brought into contact with the end portions to define the gap between the developing device and the photoreceptor. When forming such a photoreceptor, for example, wipe off the liquid pool using gauze or cloth, or press an adapter with an uneven surface against the lower end of the support during or after coating to wash away the liquid pool. Another possible method is to do so.

[Problem that the invention seeks to solve]

The above-mentioned publications disclose a method of coating by dipping, and also describe a method of avoiding a liquid pool 4 by using a taper 3 or the like. However, in the method using the taper 3, the liquid pool 4 remains in front of the slope 3 due to the influence of the degree of slope of the taper 3, the surface condition of the slope, the material of the support member, the viscosity of the coating liquid, and the temperature and humidity of the atmosphere. Sometimes the purpose is not achieved. Furthermore, all supports 1
Machining the desired taper 3 with high accuracy requires a great deal of effort, leading to problems such as increased costs. Furthermore, the method of wiping with gauze or the like requires a lot of time and effort, and has disadvantages such as the fact that the wiped coating solution, gauze fibers, etc. adhere to the photosensitive layer and cause malfunctions. Furthermore, the method of using an adapter is troublesome as it requires attachment and detachment work each time the adapter is applied, and it also has problems such as the possibility of damaging the surface of the support.

[Means for solving problems]

The object of the present invention is to accurately remove liquid pools that occur when a support is immersed in a coating liquid and to form a uniform thin film in an extremely simple and rational manner. It is an object of the present invention to provide a method for forming a thin film that allows a thin film forming body having quality characteristics to be obtained.

The above purpose is to absorb liquid pools that occur after coating on the surface of the support in a thin film forming method in which the support is immersed in a liquid tank filled with a coating liquid and the coating liquid is applied to the surface of the support. This is achieved by a method of forming a thin film in which the film is removed by a method.

[Effect]

In the present invention, when a coating liquid is applied to a support by the dipping method as described above, the coating film on the surface of the support flows down due to the action of gravity, and the liquid pool formed at the lower end of the support is removed using, for example, an aspirator. , diaphragm pump.

The support used in the thin film forming method of the present invention includes materials and Although there is no particular limitation regarding the shape, for example, in the case of an electrophotographic photoreceptor or an electrostatic recording medium, a conductive metal 1
For example, it is preferably made of aluminum, iron, stainless steel, etc., or has a conductive broken film on its surface, such as metal powder such as aluminum powder, or carbon powder.

It may be provided with a coating containing tin oxide powder, titanium oxide powder, or the like. Furthermore, films, paper, plastics, etc., on which metals such as aluminum and tin are vapor-deposited, plated, or laminated are also suitably used. The shape of the support may be cylindrical or sheet-like, but cylindrical is more preferable.

Next, as a coating liquid for an electrophotographic photoreceptor, for example, a dispersion in which an inorganic photoconductor such as zinc oxide, zinc sulfide, mercury sulfide, cadmium sulfide, titanium oxide, zinc selenide, etc. and a resin are dissolved and dispersed in an organic solvent is used. , e.g. polyvinylcarbazole,
There is a liquid in which an organic photoconductor such as polyvinylanthracene, polyvinylene, phthalocyanine, trinitrofluorenone, etc. is dissolved or dispersed in an organic solvent together with a resin if necessary.

Coating liquids for functionally separated type photoreceptors include coating liquids for charge generation layers containing, for example, perylene derivatives, chlordian blue, methylskarylium, bisazo dyes, polycyclic dyes, pyrylium salt dyes, and, for example, oxadiazole derivatives. , pyrazoline derivatives.

There is a coating liquid for a charge transport layer containing a polyarylalkane aromatic amine compound and the like. Further, coating liquids containing resins such as polyacrylic esters, polymethacrylic esters, polyvinyl chloride, polyvinyl acetate, epoxy resins, ethyl cellulose, etc., and polyurethane, polyethylene as charge transporting substances and binder resins, etc. ,
Polypropylene, polyvinyl butyral, acrylic resin.

There are coating liquids for protective layers containing methacrylic resin and the like.

Among these, the thin film forming method of the present invention is preferably used for photosensitive liquids containing photoconductive substances. Further, as a coating liquid for electrostatic recording material, for example, polyethylene is used.

polyester, polystyrene, polycarbonate.

There are liquids in which acrylic resin, silicone resin, epoxy resin, etc. are dissolved in organic solvents. Examples of the organic solvents for the various coating liquids include tetrahydrofuran.

Benzene, toluene, acetone, methyl ethyl ketone,
Ethyl acetate, butyl acetate, dichloroethane.

Examples include trichloroethane.

To apply the coating liquid to the support, fill a plastic acid or metal liquid tank that is thicker than the cylindrical support with the coating liquid, and place the support in the axial direction with respect to the liquid surface. It is applied by immersion by moving relative to the surface. The speed of the relative movement is not particularly limited, but is 1, for example, 0.1 to 50
mm/sec, and the viscosity of the coating liquid is also not particularly limited, but is, for example, 0.5 to 100 OCP.

After the coating is completed, the coating film flows down to the lower end of the support to form a liquid puddle several times the thickness of the coating film and about 1 to 15 mm in width. is removed while rotating the support. At this time, the amount of coating liquid remaining after the liquid pool is removed by the suction means may be the same amount as the coating film on the main body side, or may be a very small amount.

The suction force when using a suction device such as an aspirator or a pump is not particularly limited, but, for example, the differential pressure with atmospheric pressure is 1 to 760 sHg.

Note that the size of the suction port of the suction device such as the aspirator or pump is designed in consideration of the size of the liquid pool, and its shape is not particularly limited.

In addition, when blotting with a blotting paper or the like, it is held in contact with a liquid pool and is blotted and removed while rotating the support. The coating film is then dried using, for example, an air-conditioned drying device, but not only the drying time is shortened because the liquid pools are removed, but uneven drying due to local differences in drying speed is prevented. Productivity and quality will be improved.

〔Example〕

The present invention will be explained below with reference to Examples, but the embodiments of the present invention are not limited thereto.

[Example 1] Figures 1 and 2 are diagrams for explaining this example.
The figure is a cross-sectional view showing a state in which a cylindrical support is immersed in a coating liquid tank for coating, and FIG. The same contents as in Fig. 4 are given the same reference numerals. In Fig. 4, 5 and 6 are upper and lower lids that close the cavity of the cylindrical support l, 7 is a handle, 8 is a coating liquid tank, 9 is a coating liquid. 10 is a suction device for the liquid reservoir 4; 11 is a bottle for trapping the sucked liquid; 12 is an aspirator;
Reference numeral 3 indicates an opening/closing cock of a water faucet, 14 a suction port of the suction device 10, 15 a pipe connecting the bottle 11 and the aspirator 12, and 18 a pipe connecting the aspirator 12 and the water faucet.

First, in FIG. 1, 100,100 O each of liquid A (for charge generation layer) and liquid B (for charge transport layer) having the following formulations were prepared as coating liquid 9 to be stored in coating liquid tank 8.

Liquid A disazo pigment 2 parts by weight Tetrahydrofuran 88 parts by weight Liquid B oxadiazole derivative 4 parts by weight Polycarbonate resin 4 parts by weight Tetrahydropran 92 parts by weight The above AA liquid 000 m fl has an inner diameter of 120 mm and a height of 80 mm.
Fill the coating liquid tank 8 with a diameter of 0+sm, and
After immersing a cylindrical support 1 with a diameter of 00 mm and a height of 400 μm with the cavity closed with an upper lid 5 and a lower lid 6, it is pulled up by a handle 7 at a speed of about 10 mm/sec in the direction of arrow F to form a coating film 2a. was formed. After coating, the support 1 is taken out of the tank, and the liquid pool 4a generated at the lower end of the support 1 is removed by gently rotating the support 1 in the direction of arrow G using a suction device 1O shown in FIG. did.

At this time, the suction force was adjusted to an atmospheric pressure difference of about 5 mmHg by adjusting the amount of water with the opening/closing cock 13.Next, the coating film 2a was dried with hot air at about 80°C to form a charge generation layer with a thickness of about 1 g. Been formed.

Next, the coating liquid in the coating liquid tank 8 is changed to liquid B (viscosity: 100 CP) instead of liquid A, and the cylindrical support l is immersed in it with the upper lid 5 and lower lid 6 closed, as in the previous case, and The coating film 2b was formed by pulling it up in the direction of arrow F at a speed of about 5 mm 2 /sec. Liquid puddle 4 generated at the lower end of the support l after coating
b by the suction device 10 shown in FIG.
The sample was removed by suction while gently rotating in the direction of the sample. At this time, the suction force was set to an atmospheric pressure difference of about 10+e+sHg6.Then, the coating film 2b was dried with hot air at about 100°C, and
A charge transport layer having a thickness of 01Ls was formed.

Through the above operations, a functionally separated photoreceptor having a charge generation layer and a charge transport layer was obtained, and the film thickness variation over the entire area of the photoreceptor layer could be suppressed to within ±5%.

In addition, the photoreceptor was U-Bii manufactured by Konishiroku Photo Industry Co., Ltd.
When the copying machine was attached to a T-shirt and image formation was performed, a clear copy image with no image unevenness was obtained.

[Example 2] FIG. 3 is a cross-sectional view of a photoreceptor and a developing device for explaining Example 2, in which 20 is the photoreceptor obtained in Example 1, 21 is a charge generation layer, 22 is a charge transport layer, 23 is a developing device, 24 is a sleeve, and 25 and 2B are rollers for defining a gap between the photoreceptor 20 and the developing device 23. The photoreceptor 20 is uniformly charged by a charger (not shown) and subjected to image exposure to form an electrostatic image, which is then developed by contact with the spikes K formed on the surface of the sleeve 24 of the developer 23. At this time, developing device 2
The gap between the photoreceptor 3 and the photoreceptor 2o is strictly defined by, for example, the rollers 25 and 28. This is essential in order to achieve uniform development over the entire development area. However, if there is variation in film thickness at both ends of the photosensitive drum 20, the contact between the rollers will change, and the rollers will scrape off the convex portions of the photosensitive layer, and the powder will be mixed into the developer in the developing device 23, causing problems in development. Conditions change and uniform development is no longer achieved.

In this example, since the photoreceptor l shown in Example 1 is used from which liquid pools have been removed, such adverse effects do not occur, and extremely uniform development can be performed, resulting in A clear image without unevenness was obtained.

〔Effect of the invention〕

As explained above, according to the thin film forming method of the present invention, the liquid pool during dip coating is removed by simple means, so an extremely uniform thin film can be easily obtained, especially when forming a thin film for a recording medium. Effects such as being able to achieve high performance records are produced.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a state in which a cylindrical support is immersed in a coating liquid tank for coating, and Fig. 2 shows a state in which a liquid pool formed at the lower end of the cylindrical support is removed by a suction device. 3 is a sectional view showing the arrangement of a photoreceptor and a developing device in an embodiment, and FIG. 4 is a sectional view showing a conventional method for removing a liquid pool. l...Cylindrical support 2.2a, 2b...Coating film 4.4a, 4b...Liquid reservoir 8...Coating liquid tank 9... . . . Coating liquid 10 . . . Absorbing device 11 . . . Bottle 12 for trapping the absorption liquid.
... Aspirator 14 ... Suction port 20
... Photoreceptor 21 ... Charge generation layer 22 ... Charge transport layer 23 ...
・Developer 24...Sleeve 25...
... Coro applicant Konishiroku Photo Industry Co., Ltd. Figure 3 Figure 4

Claims (6)

[Claims] (1) In a thin film forming method in which a support is immersed in a liquid bath filled with a coating liquid and the coating liquid is applied to the surface of the support, a liquid pool that occurs after coating on the surface of the support is removed by a suction means. A thin film forming method characterized in that the film is removed. (2) The thin film forming method according to claim 1, wherein the support is a cylindrical support. (3) The thin film forming method according to claim 2, wherein the cylindrical support is moved in its axial direction relative to the liquid level in the liquid tank to apply the coating liquid. (4) The cylindrical support is applied by moving relative to the liquid level in the liquid tank in a direction substantially perpendicular to the liquid surface, and the liquid pool is formed near the lower end of the outer periphery of the support. Second
The method for forming a thin film according to item 1 or 3. (5) The liquid pool is removed by bringing the suction means into contact with or close to the liquid pool.
The method for forming a thin film according to item 1 or 4. (6) The thin film forming method according to any one of claims 1 to 5, wherein the coating liquid is a photosensitive liquid containing a photoconductive substance.