JPH0372350B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for uniformly applying a coating liquid onto the outer surface of a substrate having an endless continuous surface.

Various methods, such as spray coating, dip coating, blade coating, and roll coating, have been investigated for uniformly coating a thin film onto the outer surface of a substrate having an endless continuous surface. In particular, studies have been made to develop a coating device with excellent productivity for uniform coating of thin films such as electrophotographic photosensitive drums. However, the conventional apparatus for coating a substrate having an endless continuous surface has disadvantages such as not being able to obtain a uniform coating film and poor productivity.

In the spray coating method, the solid content concentration of the coating droplets increases because the solvent evaporates before the coating droplets ejected from the spray gun reach the outer circumferential surface of the endlessly formed base material. As a result, the viscosity of the applied droplets increases, and when the droplets reach the surface, the droplets do not spread sufficiently over the surface, or particles that have dried and solidified adhere to the surface. , it is not possible to obtain a coated surface with good smoothness. Furthermore, since the rate of droplet arrival at the substrate having the continuous surface is not 100% and is partially uneven, it is very difficult to control the film thickness. Furthermore, since polymer solutions and the like may cause stringiness, there are restrictions on the solvents and resins that can be used.

In the blade coating method and roll coating method, for example, a blade or roll is arranged in the length direction of a cylindrical base material, and the cylindrical base material is rotated to perform coating.After the cylindrical base material is rotated once, the blade or roll is It is a setback. However, when the blade or roll is retracted, the viscosity of the coating liquid causes some parts of the coating film to be thicker than other parts, resulting in a disadvantage that a uniform coating film cannot be obtained. JP-A No. 54-87229 and JP-A No. 54-128740 disclose that the blade during blade coating is connected to a change in the direction of movement of a piston in a tank or cylinder that can switch between vacuum and atmosphere, and By switching to the vacuum side when retracting, excess coating liquid is handled and a uniform coating film is obtained. However, in order to obtain a uniform coating film, it is necessary to set the suction timing and precisely control the amount of the coating liquid to be suctioned, but this method has drawbacks such as complicated and difficult control.

The dip coating method improves the above-mentioned poor coating film surface smoothness and coating film uniformity. However, controlling the coating film thickness is difficult due to the physical properties of the coating liquid (viscosity,
It is very important to adjust the physical properties of the coating liquid, which are controlled by surface tension, density) and coating speed, and the coating speed is also limited to a low level, resulting in disadvantages such as poor productivity.

In JP-A-56-15864, JP-A-56-15865, and JP-A-56-15866, a scraping blade arranged with a certain clearance around the circumference of a cylindrical base material is moved, The thickness of the film formed for coating is determined by the clearance between the scraping blade and the cylindrical base material, and this film thickness is approximately 1/2 of the clearance.In order to obtain a uniform film thickness, the cylindrical base material must be rotated. We have proposed a method of holding the scraping blade in order to maintain a constant clearance. Furthermore, when changing the coating thickness, the coating thickness will be approximately 1/2 of the clearance, so it is necessary to prepare a scraping blade that has clearance according to the required coating thickness. Every time a change is made, workers are forced to perform complicated tasks. Furthermore, since the setting accuracy of the scraping blade is the immediate film thickness accuracy, there is no play (variability) in accuracy, making it extremely difficult to finely adjust the coating film thickness.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating apparatus that can solve the various disadvantages mentioned above, obtain a uniform film thickness, and easily control the film thickness with high precision. Other purposes will become apparent from the description.

As a result of intensive research, the present inventors have completed the coating device of the present invention. The coating apparatus for a substrate having an endless continuous surface according to the present invention is capable of rapid coating and has high productivity. The coating device of the present invention has various other effects, but in particular, it can obtain a uniform film thickness,
The film thickness can be easily controlled. Moreover, it can be applied to an endless continuous surface without damaging it.

The present invention is a substrate that moves relative to a coating device and that does not have an edge in a vertical section in the direction of movement, that is, a substrate surface that has an endless continuous surface. In the device,
The coating liquid distribution slit is continuous, the coating liquid distribution slit is continuous below the coating liquid outlet and is inclined downwardly, and the endless continuous surface is slightly larger than the outer dimension of the base material. A coating device for a substrate having an endlessly formed continuous surface, characterized by having a liquid sliding surface configured to form a terminal end, and a lip-shaped portion extending downward from the terminal end of the liquid sliding surface. be.

Specifically, in an apparatus for coating the outer surface of a substrate having an endlessly formed continuous surface, the coating liquid distribution chamber and the coating liquid distribution slit connected to the coating liquid distribution chamber are continuous, and the coating liquid distribution chamber is connected to the coating liquid distribution chamber. A coating supply means is connected to the coating liquid distribution chamber, is located inside the coating liquid distribution slit, and is continuous with the coating liquid outlet of the coating liquid distribution slit on the lower side and slopes downward obliquely and is endless. A liquid sliding surface configured to terminate at a dimension slightly larger than the outer dimension of a base material having a continuous surface formed thereon, and 0.05 to 1 mm larger than the outer dimension of the base material having an endlessly formed continuous surface. , the length extending downward from the end of the liquid slide surface is 0.1 to 10 mm, preferably 0.5 to 4
It is preferable to use a coated part device having a lip-shaped part of mm. Further, the lip-shaped portion is vertically downward from the end of the slide surface and is inclined toward the opposite side from the base material within a range of up to 30 degrees from the end, and more preferably, vertically downward and within a range of up to 20 degrees from there. It extends at an angle inside.

If the slope of the lip exceeds 30 degrees, the crosslinking of the coating solution will be shortened, making it difficult to obtain a good coating film. Further, the coating liquid supplied to the coating device is temporarily stored in a coating liquid distribution chamber, and the coating liquid is uniformly distributed to a coating liquid distribution slit connected thereto. In order to distribute and uniformly apply the coating liquid distributed to the slit onto the substrate surface, the pressure loss ratio of the coating liquid distribution chamber to the coating liquid distribution slit is 40 or more, preferably 40. ~100000. If the pressure drop is less than 40, it will be difficult to uniformly distribute and apply the coating liquid, and if it exceeds 100,000, it will be necessary to enlarge the coating liquid distribution chamber or lengthen the slit, which will cause problems in the structure of the device.

The coating device of the present invention inserts a base material having an endlessly formed continuous surface into the terminal end of a liquid slide surface, moves the base material vertically upward relative to the device, and causes the liquid to flow down the slide surface. The coating liquid is applied onto the substrate having a continuous surface after forming a bridge between the lip at the end of the liquid sliding surface and the substrate having an endless continuous surface.

When the substrate having an endlessly formed continuous surface is cylindrical, the coating liquid distribution slit is circular and has a diameter slightly larger than the diameter of the cylindrical substrate (0.05~
The coating can be suitably applied by using a coating device having a cylindrical end (1 mm larger in diameter) and a conical slope.

It is preferable to use a pipe as the coating liquid supply means for supplying the coating liquid to the coating liquid distribution chamber, and two or more pipes may be used. Two or more pipes may be used to ensure safety and uniformity of the coating liquid.
A decompression chamber that cooperates with the bridge and the cylindrical base material is provided at the bottom of the bridge of the coating liquid formed between the base material and the base material having a continuous lip-like surface at the end of the liquid slide surface, and communicates with the decompression chamber. It is also possible to suitably use a coating apparatus which is provided with a gas discharge pipe to reduce the pressure in the vacuum chamber so as to keep the pressure lower than the atmospheric pressure and perform coating.

As a simple example of the present invention, Fig. 1 is a perspective view, and Fig. 2 is a perspective view.
The figure shows a cross-sectional view during coating. The coating liquid is supplied to the supply port 1 by a pump in the amount necessary for coating, is distributed in the distribution chamber 2 in the circumferential direction of the cylindrical drum, passes through the distribution slit 3, and is distributed uniformly in the circumferential direction to the slide portion 4. After flowing down the slide section,
After forming a bridge between the tip of the slide part and the outer peripheral surface O of the cylindrical base material, it is applied to the surface of the cylindrical base material.
Here, the difference between the diameter of the terminal end of the slide part and the outer diameter of the cylindrical base material is in the range of 0.05 to 1 mm, but preferably 0.1 mm.
~0.6mm range. Further, the inclination angle of the slide portion is in the range of 10 to 70 degrees with respect to the horizontal, preferably in the range of 20 to 45 degrees.

The viscosity of the liquid applied with this device is 0.5~
The range is 700 cp, preferably 1 to 500 cp. The coating film applied by this apparatus is seamless and uniform because the distribution chamber distribution slit and the sliding portion are seamlessly arranged in the circumferential direction of the cylindrical base material. Furthermore, since the coating thickness is determined by the coating supply amount and the moving speed of the cylinder diameter, it can be easily controlled, and at the same time, the coating speed can be made much faster than in the dipping method.

The tip of the slide part and the cylindrical base material are arranged with a certain gap between them, so they do not damage the cylindrical drum, and even when forming multiple layers with different properties, they do not damage the already applied layers. It can be applied without any problem. Furthermore, when using this device to form multiple layers with different properties that dissolve in the same solvent, the time spent in the solvent can be much shorter than with the immersion method, and the lower layer material will hardly elute to the upper layer side. A coating layer can be formed on the surface.

The coating solution used is supplied in the amount necessary for coating, so only a small amount is required, which is advantageous because coating and drying can be carried out in a short time even with unstable solutions where the components contained in the solution state are prone to decomposition or other deterioration. be.

This device is used for manufacturing electrophotographic photoreceptor drums and electrostatic recording media that require thin and uniform coatings, coating the surfaces of rollers, and forming coatings on the outer peripheral surfaces of endless strips. It can be used as a coating device without limitation, ie on the outer surface of a substrate having an endlessly formed continuous surface. The coating may be carried out by moving the substrate itself, which has an endless continuous surface, by moving the coating device, or by rotating a cylindrical drum.

Note that the present invention is not limited only to the shapes shown in the attached drawings.

Next, examples will be shown, but the present invention is not limited to these examples.

Example 1 A 20% ethylene chloride solution of polycarbonate resin with a viscosity of 200 cp was applied at a rate of 3 m/min in a coating device placed on a 120φ aluminum tube with a gap of 300μ.
The liquid layer was coated at a coating speed of 100 μm in thickness. As a result, the film thickness after drying was 20μ, and
The error range in the length direction was within 1μ, and a tube with a good coating film could be obtained. Using the same solution, an aluminum tube was moved at a moving speed of 0.3 m/min to obtain the same dry film thickness of 20 μm as described above by dip coating.

In addition, in the present invention, when coating in a downward film thickness within the film thickness range determined by the viscosity of the prepared coating liquid, when the viscosity of the coating liquid is too high, or when the coating speed is too high, the cylinder When the liquid applied on the circumference of the cylindrical base material at the end of the slide surface is removed, the viscosity of the liquid causes a strong force to lift the liquid at the crosslinked part upward, causing the cylindrical base material and the end lip of the slide surface to be removed. The crosslink formed between the two parts may not be able to exist stably. As described above, uniform coating may become impossible due to conditions such as variations in coating speed and variations in the gap between the cylindrical base material and the end of the slide surface. However, the disadvantage of this is that air is discharged from the vacuum chamber below the bridge, which includes the bridge and part of the surface of the cylindrical substrate as part of the wall, through the exhaust pipe, making the pressure in the vacuum chamber negative (desirably) lower than the atmospheric pressure. is 1 mm water column ~ 300 below atmospheric pressure
The application is controlled by keeping the application low (in the range of mm water column).

Example 2 In a coating device placed on a cylinder of a 120φ aluminum tube with a gap of 200μ, a solution with a viscosity of 450 cp in which 10 g of polyvinyl carbazole and 1.5 g of polycarbonate were dissolved in 100 ml of monochlorobenzene was applied at a coating speed of 3 m/min. in,
The coating was applied to a liquid layer thickness of 70 μm under the internal pressure of a decompression chamber that was 15 mm lower in water column than atmospheric pressure.

A good coated film was obtained with a film thickness of 5.5 μm after drying and a film thickness error within 0.5 μm in the circumferential direction and longitudinal direction of the substrate.

[Brief explanation of drawings]

Fig. 1, perspective view, partially sectional view, Fig. 2, sectional view during coating, Fig. 3, perspective view, partially sectional view of the coating device with two coating liquid supply pipes, Fig. 4, FIG. 2 is a sectional view of a coating device having a reduced pressure chamber during coating. 0... Cylindrical base material, 1... Coating liquid supply pipe,
2... Coating liquid distribution chamber, 3... Coating liquid distribution slit, 4... Liquid slide surface, 5... Coating film, 6...
Air exhaust pipe, 7...Bridging, 8...Decompression chamber.

Claims (1)

[Claims] 1. In an apparatus for coating the outer surface of a substrate having an endless continuous surface, the coating liquid distribution slit is continuous so as to surround the outer periphery of the substrate without having an end, and the coating liquid flow in the coating liquid distribution slit is continuous. The liquid slide has a liquid slide surface configured to continuously slope below the outlet and terminate at a dimension slightly larger than the outer dimension of the base material having the endless continuous surface. A coating device for a substrate surface having an endless continuous surface, characterized by having a lip-shaped portion extending downward from the end of the surface.