JPS624470A - Coating methdod - Google Patents

Abstract

PURPOSE:To obtain a coated film which has a uniform film thickness and is smooth even if the film is thick by sucking the solvent evaporated from a coating liquid together with air by an air suction means and drying the surface to be formed with the coated film during the formation of the coated film. CONSTITUTION:This invention relates to a method for coating an image holding member in which the air suction device 13 as the annular air suction means is provided around a cylindrical body above a short cylindrical member 6 near said member and many suction ports 14 for ejecting the air diagonally downward at the same angle are provided onn the surface of the device 13 facing the outside peripheral surface of the body 1. The solvent around the body 1 evaporated from the coating liquid 16 during the coating of the coating liquid 16 is sucked upward together with the air to dry the coated film 17. The liquid sag is thus prevented and the uniformity of the film thickness in the axial direction of the cylindrical shape is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a coating method for an image holding member, and more particularly to a coating method for forming a coating film of a uniform constant thickness on the outer peripheral surface of a cylindrical body.

(B) Conventional technology Conventionally, methods for applying a coating material to a cylindrical body include a spray method, and a method in which a ring-shaped coating liquid storage part is provided around the outer periphery of the cylindrical body coaxially with the cylinder axis of the cylindrical body. There are vertical coating methods in which either the cylindrical body or the coating liquid storage area is moved and applied, and the immersion method in which the cylindrical body is immersed in a dipping tank and the cylindrical body is pulled up or the liquid is drained from the dipping tank. Are known.

(c) Problems to be Solved by the Invention However, although the above-mentioned spraying method is excellent in mass production, it has drawbacks such as a small amount of coating per application and poor surface smoothness.

The dipping method has simple equipment and can be applied neatly to any shape of coating member (hereinafter referred to as the substrate), but it has the disadvantage of requiring a large amount of coating liquid when coating a long object. When the substrate is swollen or eroded by the solvent in the coating solution, there are problems in that not only a uniform film thickness cannot be obtained, but also residual solvent is trapped in the substrate even after drying.

On the other hand, the vertical coating method has excellent surface smoothness of the coating film, and even when coating a long object, the tolerance of the coating liquid storage section can be freely changed according to the substrate. Liquid suspension can also be applied with a very small amount. Furthermore, because the contact time between the substrate and the coating solution is short, multilayer coating is possible using the same solvent system, and even if the substrate is wetted or eroded by the solvent of the coating solution, it can be coated in multiple layers compared to the dipping method. It has the advantage that the film thickness is uniform and the amount of residual solvent after drying is so small that it is not a problem.

In the vertical coating method and dipping method, the film thickness of the coating film is
It is determined by the concentration and lifting or lowering speed of one coating liquid, and it is known that the higher the concentration and the higher the lifting or lowering speed, the thicker the film becomes.

However, if the lifting or lowering speed is fast, the coating liquid will drip before the coating dries and is fixed, and the coating will be thin at the top of the cylindrical body and thin at the bottom. A phenomenon of thickening occurs. Particularly, when the concentration of the coating liquid is low and the viscosity is high, there is a large amount of solvent, so dripping phenomenon is very likely to occur. Such a dripping phenomenon often occurs particularly when the substrate is being pulled up or the coating liquid storage section is being pulled down.

The present invention was developed in view of the above circumstances, and aims to provide a coating method that improves the vertical coating method and provides a coating film with uniform thickness and excellent smoothness even in thick films. It is.

(d) Means for Solving the Problems The present invention provides a short cylindrical member having an inner diameter larger than the outer diameter of the vertical cylindrical body and provided substantially coaxially with the cylinder axis of the vertical cylindrical body; The coating liquid is stored in the coating liquid storage circle formed around the cylindrical body by the cylindrical member and the shield member that seals the lower end of the space between the outer peripheral wall of the cylindrical body. , instead of moving only the cylindrical body upward, 1↓, moving only the short cylindrical member downward, or moving the cylindrical body upward and the short cylindrical member downward to form a coating film on the outer peripheral wall of the cylindrical body. A coating method for forming a cylindrical body, the solvent being evaporated from the coating liquid around the cylindrical body during application of the coating liquid, together with air, by an air intake means provided around the cylindrical body near the upper part of the short cylindrical member. It is something that attracts attention.

<B> Effect The present invention is designed to dry the surface on which the coating film is formed by sucking the solvent evaporated from the coating solution together with air by the suction means during the coating film formation.

(f) Examples The present invention will be described in detail below based on examples shown in the figures. Note that the present invention is not limited to this.

FIG. 1 is an enlarged cross-sectional view of essential parts of an example of a coating device used in carrying out the present invention.

In the figure, (1) is a vertical cylindrical body, [2+ (
2+ is a lid plate that is locked to the openings at both ends of the cylindrical body (1) and closes the openings; an arm (3) that moves up and down is provided above the cylindrical body (1); ), pass through both cover plates (2) and attach a nut (4) to the lower cover plate ('2J)
) is installed with a fixed support @(5).

Around the cylindrical body (1), a plate-shaped horizontal member (the sword is provided so as to be movable in the vertical direction) has an insertion hole (6) for inserting the cylindrical body (1). (A sheet-shaped shield member (8) is placed on the upper surface of the sword, and a cylindrical body (1) is placed in the center of the shield member (8).
An opening (not shown) is provided with a diameter smaller by about 1 mm to 51 mm than the outer diameter of the opening. In addition, the shield member (8)
is placed so that the center of its opening coincides with the cylinder axis of the cylindrical body (1) inserted into the insertion hole (6). Roughly, the horizontal member (for the sword,
A short cylindrical member (9) having an inner diameter larger than the outer diameter of the cylindrical body (1) is inserted into the insertion hole (6) and coaxially with the cylindrical axis of the cylindrical body (1). Fixing jig QO),
It is fixed by a bolt (11) and a nut surface.

This fixes the shield member (8).

The material of the shield member (8) may be flexible and stable against the solvent of the coating liquid, preferably having good slip properties. Specific examples thereof include polyethylene, polypropylene, silicone rubber, fluororubber, etc., but the present invention is not limited to these.

Further, in the vicinity of the cylindrical body (1) and above the short cylindrical member (6), an inlet device (hereinafter referred to as a draft) 03) as a ring-shaped intake means is provided. 13) The surface facing the outer peripheral surface of the cylindrical body (1) is
Numerous suction ports that blow out air diagonally downward at the same angle (
I4) is provided. Note that the draft 03) is not limited to a ring shape, and may have any shape as long as it can uniformly suck in the solvent vapor and air around the cylindrical body (1).

Further, the suction angle on each suction port side is configured to be variable.

Next, a method of forming a coating film using the above apparatus will be explained.

First, the cylindrical body (
The coating liquid (5) is stored in the concave coating liquid storage part 05) formed around the area 1), and the cylindrical body (1) is moved upward to form the coating film (I7). Form. At this time, during the application of the coating liquid (16), the solvent around the cylindrical body (1) that has evaporated from the coating liquid (16) is removed together with air into the draft (1).
3) Dry the coating film [17] by suctioning upward.

Therefore, the coating film can be dried faster than in the conventional example. Therefore, it is possible to prevent the ff1I liquid from dripping in the direction of gravity, thereby improving the uniformity of the film thickness in the axial direction of the cylindrical body (1). In addition,
By appropriately changing the suction direction of the draft a3) depending on the coating liquid used, it is possible to prevent the surface of the coating film from being disturbed by the suction force of the draft (131), and at the same time, it is possible to prevent liquid dripping. Also, if the suction flow rate is too high, turbulence will occur on the coating surface, so the suction flow rate should be set to 0.
．． It is preferable to set it to about 1 to 5 m7 seconds or less.

In addition, in the above method, the cylindrical body (1) is pulled up to form a coating film, but this narrow cylindrical body (1) is fixed and a horizontal member (which pulls down the force to form a coating film) is used. Alternatively, the coating film may be formed by moving the cylindrical body (1) upward and the horizontal member (sword) downward.

The method of the present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 and Comparative Example 1 In the apparatus shown in Fig. 1, the suction flow rate on the coating film surface was 0.2 m/sec.The acute angle cylindrical body had an angle formed by the suction direction of troughs 1 to 03) and the coating film surface at 30°. Distance between (1) and draft (13) lIllt
Diameter of opening of 10ml shield member (8)
Pulling speed of 140mm cylindrical body (1) 7cm/
The outer diameter is 150nun with the following coating liquid under n+in conditions.
The coating was applied to an aluminum pipe having a length of 96 CIl.

Coating liquid: Polyurethane resin 10 parts by weight (fixed content 24.9%) Preliminary dispersion of carbon black 20 parts by weight (solid content 35.3%, carbon black/binder (urethane) ratio = 0.3) Methyl ethyl ketone
10 parts by weight Dry solid content: 23.9% Viscosity: 980 cps The above formulation was stirred for 10 minutes and left to stand for 10 minutes to defoam to prepare a coating liquid.

As a comparative example, a film was formed using the same coating solution as in the example without using a draft. Table 1 shows the results of measuring the film thickness and surface roughness of the obtained coating film.

From Table 1, it is clear that those using a draft are superior in uniformity of film thickness and surface smoothness compared to those not using a draft.

Example 2 and Comparative Example 2 Using the following coating liquid under the same equipment and conditions as Example 1,
The coating was applied to the outer peripheral wall of a soft drum 08) as shown in FIG. However, the diameter of the opening (8) in the shield member is 74 mm. In FIG. 2, (19) is an aluminum pipe, and ▪ is a urethane rubber layer cast onto the aluminum pipe. The aluminum pipe had an outer diameter of 74 mm and a length of 35 c+a, and the urethane rubber layer had an outer diameter of 84 mm, a thickness of 5 mm, and a length of 30 cm.

Coating liquid: Polyurethane resin 10 parts by weight (solid content 24.9%) Carbon black preliminary dispersion liquid 20 parts by weight (solid content 35.3%, carbon black/binder (
Urethane) ratio = 0.37) Methyl ethyl ketone
45 parts by weight Dry solid content: 12.7% Viscosity: 70 cps The above formulation was stirred for 10 minutes and left to stand for 10 minutes to defoam to prepare a coating liquid.

As a comparative example, a film was created using the same coating solution as in the example without using a draft. Table 2 shows the results of measuring the film thickness and surface roughness of the obtained coating film.

From Table 2, it is clear that those using a draft are superior in film thickness uniformity and surface smoothness compared to those not using a draft.

Example 3 and Comparative Example 3 Using the same equipment, conditions, and coating liquid as in Example 1, the third
The coating was applied to the outer peripheral wall of a soft drum (21) as shown in the figure. However, the diameter of the opening of the shield member (9) is 74 mm. In Figure 3, the lower part is an aluminum pipe,
The cutter is a foamed urethane rubber layer formed on an aluminum pipe, and the heat shrink tube is provided to cover the foamed urethane rubber layer.

The outer diameter of the aluminum pipe is 74 mm and the length is 35 cm, the outer diameter of the foamed urethane rubber layer is 84 mm, the thickness is 5 mm, and the length is 30 cm, and the heat shrink tube is made of polychloride. Made of vinyl and tightly adheres to the foamed urethane rubber layer. As a comparative example, a coating film was formed by dipping using the same coating solution as in Example 3 at the same speed.

Table 3 shows the results of measuring the film thickness and surface roughness of the obtained coating film. However, in Comparative Example 3, the heat shrink tube &41 was attacked by the solvent and peeled off within about 1 minute after the soft drum 2+1 was immersed and pulled up, making coating impossible.

From Table 3, it is clear that according to the present invention, the film thickness is uniform and the surface smoothness is excellent even when the cylindrical body has low stability against the solvent of the coating liquid. .

The coating material used in the method of the present invention is not limited to those described in the examples, but any known photoconductive material, insulating material, or conductive material can be applied. For example, photoconductive materials include phthalocyanine, ZnO1Cd S, T! 02
, PVK, TNF, 7zo pigments, and other known organic and inorganic materials. Insulating materials that can be combined with these or used alone include polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, polyester, (meth)acrylic, polyvinylpyrrolidone,
Polymer resins such as methylcellulose, hydroxypropylmethylcellulose, polyvinyl butyral, polyimide, polyamideimide, polyarylate, polysulfone, polyamide, fluororesin, and polyurethane are used.

As conductive materials, carbon black, Ketjen black, tin oxide, indium oxide, antimony trioxide, zinc oxide, titanium black, potassium titanate, etc. are used in combination with the insulating substances listed above. . Further, an insulating resin alone can also be used.

(1.) Effects of the Invention According to the present invention, it is possible to prevent the coating liquid from dripping and to form a uniform and smooth coating film even in the case of a thick film.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of a main part showing an example of a coating device used to carry out the coating method of the present invention, and FIGS. 2 and 3 are enlarged cross-sectional views of a cylindrical body of this example of the device. . (1)...Cylindrical body, (6)...
・Insertion hole, (7)...Horizontal member, (8)・
...Shield member, (9) ...Short cylindrical member, 03) ...Draft (intake means), 05)
・・・・・・Coating liquid storage part, 06)・・・Coating liquid, No. 111ff Procedure Neichi rE document (method) 1, Incident indication Patent Application No. 142733 of 1985 2, Method of applying the name of the invention 3, relationship with the case of the person making the amendment Patent applicant address 1 Teppo-cho, Sakai City, Osaka Name (290) Daicel Chemical Industries, Ltd. Representative Kubo 1) Mi Fumi 4, Agent 〒 530 Address 5-1-3 Quarter Nishitenma, Kita-ku, Osaka
One Bill 5, "2nd and" on page 15, line 12, for issuing the date details of the amendment order, changed to "2nd and"
Correct to.

Claims (1)

[Scope of Claims] 1. A short cylindrical member having an inner diameter larger than the outer diameter of the cylindrical body and provided approximately coaxially with the cylinder axis of the vertical cylindrical body, and an outer periphery of the short cylindrical member and the cylindrical body. The coating liquid is stored in a coating liquid storage area formed around the cylindrical body by a shield member that seals the lower end of the space between it and the wall, and only the cylindrical body is placed upward. In a coating method in which a coating film is formed on the outer peripheral wall of a cylindrical body by moving only the short cylindrical member downward, or by moving the cylindrical body upward and the short cylindrical member downward, the coating liquid A coating method characterized in that during coating, the solvent around the cylindrical body evaporated from the coating liquid is sucked together with air by a suction means provided around the cylindrical body near the upper part of the short cylindrical member.