JPS6331736Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a coating device for applying a coating liquid to a continuously running web, and in particular, a nozzle-type coating head having a slit at the tip for supplying the coating liquid and an air knife device. The present invention also relates to a coating device.

Conventionally, in the coating method, the excess coating liquid applied to the web surface is measured using an air knife device to blow off the excess coating liquid applied to the web surface with an air jet to achieve the desired predetermined coating amount. There are roll methods, dip methods, fountain methods, etc., but the roll method tends to cause bubbles to form in the coating solution, making it difficult to obtain a high-quality coating, and the dip method tends to avoid excess coating during high-speed coating. The drawback is that it is difficult to control the liquid supply.
In contrast to these methods, the fountain method is less likely to generate bubbles and is suitable for controlling the coating liquid supply during high-speed coating.

The fountain method has a nozzle-type coating head with a slit at the tip for supplying the coating liquid to the web surface, and from this slit, an excess coating amount than the desired predetermined coating amount is supplied to the running web surface. The excess coating liquid is blown off by an air jet from an air knife device to obtain the desired coating amount.

Usually, the slit width of the fountain-type coating head is set to the same length as the coating width of the coating liquid applied to the web surface. The width of the nozzle can be determined by adjusting both ends of the nozzle at the nozzle design stage to prevent the coating liquid from spilling out from both ends of the slit, or by using a material such as film after the nozzle is manufactured. Measures such as closing both ends of the nozzle are taken, but the width of the nozzle is only a few millimeters to 10 millimeters longer than the coating width.
The nozzle width and application width are approximately the same length.

However, if the coating liquid is supplied to the web surface using a nozzle with approximately the same width as the coating width, and the excess coating liquid is blown off with an air jet in order to achieve the desired coating amount,
The coating liquid on the edges of the web to which the coating liquid has been applied spills out from the web, causing the so-called "back-wrapping" phenomenon in which the coating liquid wraps around the back side of the web, and the web with the back-wrapping cannot be used as a product and is discarded. . Even if backing does not occur, the amount of coating applied to the edge portions may not reach the predetermined amount, or the coating may be extremely uneven, resulting in the product being discarded. This phenomenon occurs significantly when the air pressure used to blow off excess coating liquid is high, when the viscosity of the coating liquid is low, or when there is a large amount of excess coating liquid.

This phenomenon is caused by the fact that the air blowing from the air knife flows around the nozzle at the edge of the coating width, and the coating liquid protrudes from the coating width and is blown away along the flow of this wind. It is thought that there are.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air knife coating device using a fountain method that can eliminate the above-mentioned drawbacks.

The object of the present invention is achieved by providing non-coating liquid supply portions of about 30 mm or more, preferably about 50 mm or more, on both sides of the coating width of the nozzle slit.

That is, the present invention uses a nozzle-type coating head having a slit at the tip for supplying the coating liquid to a continuously running web, and applies the coating liquid in excess of the desired predetermined coating amount. In a coating device that measures surplus coating liquid to a predetermined coating amount using an air knife device, in addition to the coating width of the slit, the nozzle has a coating on both sides of the coating width of the slit.
This coating device is characterized in that each non-coating liquid supply section is provided with a length of about 30 mm or more.

The present invention will be explained in detail below with reference to the drawings. 1st
The drawing shows a fountain-type air knife coating device in which a coating liquid 5 is supplied from a slit 4 of a nozzle 3 to the surface of a web 2 running along the surface of a coating bucking roll 1, and the excess coating liquid is transferred to an air knife 6. This shows the situation in which the amount of coating is measured to a predetermined amount by blowing it off with an air jet.

Although FIG. 2 shows a conventional nozzle, and FIGS. 3 and 4 show embodiments of the nozzle according to the present invention, the present invention is not limited thereto.
In the figure, a indicates a slit for supplying a coating liquid made to match the coating width, and b indicates non-coating liquid supply portions provided on both sides of the slit a in the coating width direction. In the present invention, each b is about 30 mm or more, preferably about 50 mm or more in the coating width direction. This upper limit of length is not limited for reasons of effectiveness of the present invention, but
It may be set to any length for reasons such as handling or cost.

In the present invention, the non-coating liquid supply surface b may be on the same plane as the slit tip a of the nozzle, or may be slightly concave or convex;
It is preferable to have a slightly concave shape on the order of mm or less.

Example In the nozzle shown in Fig. 3, the slit a is
A nozzle-type coating head of the present invention with a width of 1100 mm and a coating liquid non-supply part b of 100 mm on both sides of the slit was manufactured and used as nozzle 3 of the fountain-type air knife coating device shown in Fig. 1 at a rate of 100 m/min. When a silver halide photographic emulsion was coated on a polyethylene terephthalate film with a width of 1150 mm that was running at high speed, a uniform coating film was obtained without any backing phenomenon. On the other hand, when the conventional nozzle-type coating head shown in FIG. 2 having a slit a of the same width was applied in the same manner, development occurred around the back side and uneven coating occurred at the edges.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a coating situation using a fountain type air knife device, Fig. 2 is a perspective view of a conventional nozzle type coating head, and Figs. 3 and 4 are nozzle type coating showing an embodiment of the present invention. FIG. 3 is a perspective view of the head. 1... Application backing roll, 2... Web,
3... Nozzle type coating head, 4... Slit part at the tip of the nozzle, 5... Coating liquid, 6... Air knife,
7... Coating liquid recovery device, a... Slit, b... Non-coating liquid supply section.

Claims (1)

[Scope of utility model registration request] Using a nozzle-type coating head with a slit at the tip for supplying coating liquid to a continuously running web, the coating liquid is applied in excess of the predetermined coating amount, and this excess coating liquid is removed by air. A coating device that measures a predetermined amount of coating using a knife device, characterized in that in addition to the coating width of the slit, the nozzle is provided with non-coating liquid supply portions of approximately 30 mm or more each on both sides in the width direction of the slit. coating equipment.