JPS5857231B2 - Tofuhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to bead coating methods.

Specifically, it can be applied to long materials to be coated, such as photographic materials and film supports for magnetic tapes, as well as sheet-like materials that are difficult to bead coated (so-called sheet materials).
It can also be applied to thin metal films (thin films that easily deform into corrugations), and it is possible to apply a smooth thin film using a low-viscosity coating liquid, and the coating liquid is supplied from a coating liquid supply device that can regulate the amount of liquid supplied. This invention relates to a bead coating method in which the coating thickness can be controlled depending on the amount.

More specifically, the coating must be to the extent that no coating failure occurs when coating the material under conditions in which the material is crimped and clamped between a coating roll and a nip roll, both rotating in the same direction as the conveying direction of the material. The applicator roll has unevenness formed on the surface of the coating roll, and even if the coating roll and the material to be coated come into contact, a considerable part of the meeting area maintains the gap necessary to form a bead, so that the coating roll and the material to be coated are The present invention relates to a coating method in which coating is performed by forming a bead at the meeting point with the material.

Thin film coating methods that can be used in the production of conventional photographic materials include dip coating, roll coating methods such as double coating, gravure coating, and slide hopper coating. There are drawbacks.

The roll coating method cannot coat sheet materials, and the regulation of the coating thickness of the material depends on the physical properties and coating speed of the coating liquid, and the amount of coating liquid is regulated by the coating liquid supply device. Since this method cannot be used as a coating method, it has drawbacks such as the need to strictly control the physical properties of the coating liquid in order to maintain a constant film thickness.

On the other hand, the gravure coating method is applied to coating liquids with relatively high viscosity and is unsuitable for coating liquids with relatively low viscosity, and the coating film thickness is almost unique to the shape of the gravure on the coating roll surface. Therefore, in order to change the coating film thickness (coating film thickness after drying), it is necessary to replace the coating roll with a gravure-shaped coating roll that can obtain the desired coating film thickness, or to change the concentration of solids in the coating liquid. There are drawbacks such as the need to make changes, making work management complicated.

Also, according to the gravure coating method,
When using a doctor knife as described in Publication No. 6, etc., or by using a glue spreading tool having a protruding surface that contacts the cloth roll as described in Japanese Utility Model Application No. 49-111509 etc., excess adhering glue is cut off. In any case, such as when
Since it is necessary to supply an excessive amount of coating liquid to the coating roll, it is not only impossible to control the coating film thickness by the amount of coating liquid supplied, but also it is necessary to dispose of the excess coating liquid. There are cases.

As described above, the gravure coating method described in the above-mentioned Japanese Utility Model Publication No. 49-111509 is a technique in which a coating liquid is directly applied from a coating device onto a material to be coated, and it is necessary to greatly vary the coating film thickness. For example, if it is necessary to change the coating film thickness beyond the range of liquid volume that can be directly transferred to the material to be coated by placing it in the recess of a gravure roll, it is necessary to use a volume that can accommodate such a large volume of liquid. It is necessary to convert it into a gravure roll with a recessed part.

A drawback is that a new gravure roll must be used each time the coating thickness differs.

In addition, in the gravure coating method described in Utility Model Application Publication No. 49-111509, etc., in which the coating liquid is directly applied onto the material to be coated, in order to smooth the coating thickness, an excess coating liquid is supplied to the gravure roll. and scraping with a blade before application is required.

Furthermore, the slide hopper coating method creates a gap of at least several hundred microns between the material to be coated and the edge of the coating device, and forms a bead at this gap point. The gap required to form the gap needs to be highly accurate, and therefore the coating device and the equipment for conveying the material to be coated are required to be highly accurate and are very expensive.

Furthermore, even if there is a slight scratch on the etch of the coating device, this scratch will generate coating streaks parallel to the coating direction on the material to be coated, and the product obtained by coating may be a photographic material, for example. In such a case, a serious failure may occur, so when the material to be coated is a thin metal plate, special care must be taken during manufacturing.

Moreover, if the gap formed between the material to be coated and the edge of the coating device is wide, the bead formed in this gap will not generate the necessary and sufficient force to wet the material to be coated, e.g. during coating. If the film is very thin, about 10-odd microns in thickness, the coating speed will need to be reduced considerably even if the gap between the edge of the coating device and the material to be coated is made extremely narrow, less than 100 microns. Therefore, it is difficult to use it practically, for example, for coating a coating liquid using a solvent.

Furthermore, this coating method has the disadvantage that it cannot be applied to a sheet-like material to be coated.

However, this method of coating by forming a coating liquid bead has the following advantages.

That is, in the bead coating method, as shown in Japanese Patent Publication No. 33-8977, the coating liquid is not directly applied from the coating device onto the material to be coated, but the coating device maintains a bead of the coating liquid and applies the coating liquid directly onto the material to be coated. A coating method in which the surface of the material to be coated, which moves across the coating liquid bead, picks up the coating liquid from the coating liquid bead (see lines 2 to 38 of the left column on page 4 of the publication).

), the thickness of the coating film is determined by the action of the coating liquid bead and can be changed depending on the speed at which the material to be coated moves, the supply rate of the coating liquid, etc.

Therefore, there is an advantage that there is no need to change the coating device each time the coating thickness is changed, as is the case with the gravure coating method described in the above-mentioned Japanese Patent Publication. This is a technique used in certain cases.

The present invention improves the drawbacks of the conventional coating methods as described above, and can be applied not only to long objects such as films but also to sheet-like objects, and can also be applied to thin metal plates that are easily deformed into liquid form. It is an object of the present invention to provide a coating method that allows smooth coating of a thin film and allows easy regulation of the thickness of the coated film.

Another object of the present invention is that there is no need to change the coating roll when regulating the coating film thickness, and the point is equal to the amount necessary for the desired coating thickness and the coating roll and the material to be coated meet. It is an object of the present invention to provide a coating method in which it is sufficient to form a bead on the surface and to supply a certain amount of coating liquid capable of maintaining the bead, and the thickness of the coating film can be easily controlled.

Another object of the present invention is to provide a coating method that can be applied to thin film coating with a low viscosity of about 1 to 10 c, p and is also suitable for coating solvent-based coating liquids. .

Furthermore, another object of the present invention is to provide a coating method in which the coating apparatus and equipment for conveying the material to be coated are not as expensive as the conventional slide hopper coating method.

Yet another object of the present invention is to provide a coating method that can easily obtain extremely thin coating thicknesses, such as coating thicknesses of 10 to 20 microns.

The above object of the present invention is that, instead of applying the coating liquid directly from the coating device onto the material to be coated, the coating device maintains a bead of coating liquid and moves the coating material across the bead of coating liquid. In the bead coating method in which the surface of the coating liquid is picked up and taken off from the coating liquid bead, the coating device has unevenness on the surface that forms a gap in which the coating liquid bead can be formed between the coating device and the material to be coated. Under conditions in which a roll is used and the material to be coated is held and conveyed by the coating roll rotating in the same direction as the moving direction of the material to be coated and a nip roll arranged below the coating roll, The amount of coating liquid required for the coating film thickness is supplied to the coating roll from the coating liquid supply port of the coating liquid supply device that can regulate the amount of supplied liquid, and the coating liquid is supplied as is without cutting off the coating liquid with a doctor blade or the like. A coating material that continuously transfers a coating liquid together with the coating roll, continuously supplies the coating liquid to a coating liquid bead formed between the coating roll and the material to be coated, and moves across the coating liquid bead. This is achieved by a bead coating method characterized in that the surface of the material is coated while maintaining a bead of coating liquid from which the coating liquid is taken up.

That is, one of the features of the present invention is that, like the bead coating method described in the above-mentioned Japanese Patent Publication No. 338977, a gap necessary for forming a bead at the meeting point between the coating device (coating roll) and the cloth material is created between the coating roll and the coating device. Rather than forming the coating roll in a space where it does not come into contact with the material to be coated, the coating roll is processed to press the coating roll against the material to be coated with the nip roll, and then the meeting point between the coating roll and the material to be coated is formed. A large part of this is to be able to maintain the gap necessary to form beads, and specifically, to form irregularities on the surface of the coating roll to the extent that they do not cause coating failure when coating the material to be coated. Another feature of the present invention is to maintain the necessary gap to form a bead in a substantial portion of the meeting area even when the applicator roll and the material to be coated come into contact. First, as in the conventional bead coating method, the coating film thickness is determined by the action of the coating liquid bead, but in the case of the present invention, the coating roll is used which also has the role of clamping and transporting the material to be coated. In this case, the coating liquid is regulated and supplied by a coating liquid supply device that can regulate the amount of liquid supplied, and the liquid is continuously moved along with the coating roll without draining the liquid with a doctor blade etc. It is to supply the

In other words, the coating liquid supply port of the coating liquid supply device that can regulate the amount of liquid supplied is provided in a manner similar to the coating roll, and the coating liquid is supplied to the coating roll in an amount necessary for the coating film thickness. The process involves forming a bead between the material and the material to be coated.

The bead coating method according to the present invention can be clearly distinguished from the gravure coating method described in Japanese Utility Model Application Publication No. 111509/1983 by the presence or absence of coating liquid beads.

That is, in the case of the technique described in the patent publication, the coating liquid in the recesses on the surface of the coating roll is directly transferred to the material to be coated and no coating liquid bead is formed, whereas in the case of the present invention, The coating liquid in the recesses on the roll surface is not directly transferred to the material to be coated, but is continuously poured onto the coating liquid bead.

The coating liquid bead in the present invention is maintained continuously during coating.

In order to maintain such a coating liquid bead continuously during coating, the surface of the coating roll is provided with unevenness, and the coating liquid is supplied from the coating liquid supply port in an amount necessary for the coating film thickness. It is.

The state of implementation of the method of the present invention is such that the coating liquid supplied to the coating roll is once poured into the coating liquid bead, and the surface of the material to be coated draws out the coating liquid from the coating machine bead. You can check it.

Hereinafter, details of the present invention will be explained together with examples shown in the drawings, but the embodiments of the present invention are not limited thereby.

FIG. 1 is a longitudinal sectional view showing an embodiment of the coating device used in the present invention, in which a coating roll 2 having an uneven surface 1 is shown.
and a nip roll 3 made of an elastic rubber material, etc., press and hold the material 4 to be coated, and this coating roll 2 is driven by a drive device (
Not shown.

) to convey the material 4 to be coated in the direction of the arrow.

A coating liquid supply lower of a coating liquid supply device 6 having a liquid volume regulating device 5 such as a pump is provided adjacent to the coating roll 2, so that the coating liquid 8 in an amount necessary for the coating film thickness is uniformly distributed on the coating roll. However, in this case, by forming a bead 9 in the gap between the etch forming the coating liquid supply lower and the coating roll 2, a more uniform coating liquid can be supplied onto the coating roll. It is preferable to

If the coating liquid is supplied onto the coating roll 2 as described above and a bead 10 is formed at the point where the coating roll and the material to be coated meet, this bead 10 will form a relationship between the coating liquid supply amount and the coating speed. It is applied to the material to be coated while maintaining the appropriate size.

Maintaining the coating liquid bead in this manner is the same as in the conventional bead coating method.

In thin film coating according to the present invention, the bead 10 is maintained in a fairly small state during coating, so even if the material to be coated is a sheet, the sheet can be continuously fed and its edges are fed close together. The coating will be smooth.

Further, even if the material to be coated is easily deformed into a wave shape, such as a thin metal plate, the bead is spread while being crimped and clamped by both rolls 2 and 3, so that there is little influence and smooth coating is performed.

In the present invention, the supply amount of the coating liquid supplied to the coating roll is regulated so that it is the amount necessary for the coating film thickness of the material to be coated, and the supply amount is regulated so that the coating liquid is supplied to the coating roll at the point where the coating roll and the material to be coated meet. Although the feature is that a bead is formed, as a specific embodiment of this liquid amount regulation, in addition to the method shown in FIG. 1, the methods shown in FIGS. 2 and 3 may also be used.

That is, as shown in FIG. 2, a side plate 12 is provided that regulates the coating liquid supply lower formed between the coating roll 2 and forms a coating liquid storage tank 11, and the side plate 12 is provided to control the coating liquid supply lower formed between the coating roll 2 and the coating liquid storage tank 11, and to apply the coating liquid to the storage tank 11 as necessary to achieve the coating thickness. A method may be adopted in which the amount is supplied from the liquid amount regulator 5 and the coating liquid supply lower is regulated by adjusting the side plate 12 so that the liquid level in the storage tank 11 is constant, or as shown in FIG. Adjust the amount of coating required to coat the material using the liquid volume regulator 5.
Therefore, the regulation roll 13 provided on the side of the application roll 2
The coating liquid is supplied to the coating liquid storage tank 11 formed by
The coating liquid supply lower formed between the coating roll 2 and the regulation roll 13 is regulated so that the liquid level of the coating material 1 is constant, and the amount of coating required for the coating thickness of the material to be coated is applied onto the coating roll. A method of supplying a liquid may be used, and the method of controlling the amount of application is not limited.

The coating roll 2 according to the present invention needs to have irregularities on its surface, but such irregularities can form an appropriate gap at the point where it meets the material to be coated, and the bead 1 can be formed in the gap.
If the shape is finer than a certain level so that the unevenness does not inhibit the formation of 0 and does not cause coating failure when the coating liquid is supplied to the material to be coated, it can be used in the form of a lattice, diagonal lattice, or pyramid. The shape does not matter, such as a concave shape such as a mold, a convex shape such as a circular or rectangular shape, or a spiral groove as shown in FIG.

Even in the case of a lattice-like structure, the bead coating method of the present invention can be applied depending on the coating liquid supply amount, coating speed, etc.

That is, if the recesses arranged in a grid have a depth necessary to form a bead of coating liquid in a considerable portion of the area where they meet the material to be coated, the coating speed and the amount of coating liquid supplied can be adjusted. This makes it possible to apply the liquid while maintaining the bead.

However, in the case of high-viscosity coating liquids, which are not applicable to conventional bead coating methods, it is difficult to apply the coating while forming beads even in the present invention, and the coating liquid to which the present invention applies also does not apply to conventional bead coating methods. Like the coating method, it is limited to low viscosity coating liquids.

The material to be coated in the present invention needs to be conveyed while being crimped between a coating roll and a nip roll, and the method for conveying the material to be coated is not only by driving the coating roll as described above, but also by using a take-up roll. Any method is acceptable, such as using .

In either method, the applicator roll and the nip roll may press and hold the material to be coated and rotate in the same direction as the conveyance direction of the material to be coated.

As described above, according to the method of the present invention, the gap necessary to form a bead is formed at the point where the coating roll and the material to be coated meet, so that it can be applied not only to long objects such as films but also to
It can be applied to sheet-like materials that are difficult to apply using bead coating using a conventional slide hopper, as well as thin metal plates that are easily deformed into corrugations, and there is no need to change the coating roll as in conventional gravure coating methods. , it is easy to control the coating film thickness, the equipment for conveying the coating device and the support to be coated does not need to be expensive like a slide hopper, and the above-mentioned gap is made to be a very narrow gap of about 20 microns. This can also be easily done by forming irregularities on the surface of the coating roll, so bead coating is possible even with a very thin coating film thickness of 10 to 20 microns.

For this reason, in the case of thin film coating even though it is bead coating, smooth coating is possible on a sheet-like material to be coated.Moreover, the bead coating method of the present invention can apply the coating liquid in the amount necessary for the coating thickness. Since the liquid is supplied onto the coating roll from the liquid supply device, it can be used as a coating method that allows the liquid amount to be regulated.
Since it is easy to change the coating thickness by regulating the amount of liquid, it is possible to obtain a gain in terms of quality control, and since it is a bead coating method, it is suitable for coating thin films with a low viscosity of about 1 to 10c, p. This is suitable as a coating method for a solvent-based coating liquid, where it is desirable to coat as thin a film as possible from the standpoint of pollution, work, and safety measures.

Hereinafter, specific examples will be given to illustrate the effects of the present invention.

Example 1 Using the coating device of the embodiment shown in FIG. 1, the gap between the coating liquid supply port (etch) 7 of the coating liquid supply device and the coating roll 2 was set to 200 microns, and the unevenness of the coating roll was as shown in FIG. A spiral groove as shown, the depth of the groove is 100 microns,
Using a pitch of 200 microns, the coating liquid supply amount was 60 cc/min per 1 m during coating, and the coating speed was 3.
m/rIu! When a coating liquid containing ethylene glycol monomethyl ether as the main solvent and having a viscosity of lc and p was applied to a thin aluminum plate, a stable bead was formed in the gap between the coating roll and the thin aluminum plate, and the coating film thickness increased to 2.
A smooth and good coating film of micron diameter was obtained.

Example 2 Using the coating device and coating roll of Example 1, the same coating solution was supplied at a coating solution supply rate of 300 CC7m per 1m during coating.
When the same thin aluminum plate was coated with 1yt1 at a coating speed of 15 m/min, stable beads were similarly formed and a smooth and good coating film with a coating thickness of 20 microns was obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 3 are vertical cross-sectional views showing specific examples of the coating device used to carry out the method of the present invention, and FIG. 4 shows an example of the coating roll according to the present invention. It is a partially enlarged front view. 1 is an uneven surface, 2 is a coating roll, 3 is a nip roll, 4 is a material to be coated, 5 is a liquid volume regulator, 6 is a coating liquid supply device, 7 is a coating liquid supply port, 8 is a coating liquid, and 10 is a bead.

Claims (1)

[Claims] 1. Rather than applying the coating solution directly from the coating device onto the material to be coated, the coating device maintains a bead of coating solution and the surface of the material to be coated moving across the bead of coating solution In a bead coating method in which a coating liquid is taken up from a liquid bead, a coating roll having an uneven surface that forms a gap between it and the material to be coated to form a bead of the coating liquid is used as the coating device; The amount of liquid to be supplied is regulated under conditions in which the material to be coated is conveyed while being crimped between the coating roll rotating in the same direction as the moving direction of the coating material and a nip roll disposed below the coating roll. The amount of coating liquid required for the coating film thickness is supplied from the coating liquid supply port of the coating liquid supply device to the coating roll, and the supplied coating liquid is directly transferred to the coating roll without cutting off the coating liquid with a doctor blade or the like. The surface of the material to be coated is continuously supplied to a bead of coating liquid formed between the coating roll and the material to be coated, and the surface of the material to be coated that moves across the bead of coating liquid is coated. A bead coating method characterized in that coating is carried out while maintaining a bead of the coating liquid from which the liquid is taken up.