JPH0584459A - Coating device - Google Patents

Abstract

(57) [Summary] [Purpose] Of the coating methods for coating various thin films such as photographic films, magnetic tapes, and photographic paper,
In stripe coating by the die coating method, which has recently attracted attention as a rational method, uneven coating of the stripe film
The purpose is to solve the disorder of the film edge and the entrainment of air, and obtain a uniform and stable coating film. [Structure] Paint measuring groove 26 and supply paint discharge opening 25
With the configuration in which the edge portion 27 formed by and has a sharp edge of 50 μm or less, there is no change in the liquid pressure of the paint in the measuring groove 26, and as a result, uneven coating due to the fall of the film 21 can be avoided and a uniform film can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus which realizes uniform and stable thin film coating.

[0002]

2. Description of the Related Art For coating a thin film such as various photographic films, magnetic tapes, photographic papers, etc.
Conventionally, various coating methods such as a gravure coating method, a reverse coating method, and a die coating method have been used, and they have been properly used depending on the purpose of use. Of the above coating methods, in the case of stripe coating, the die method (floating die) shown in FIG. 4 is the most efficient. In FIG.
1 is a die main body, 2 is a paint reservoir, 3 is a flow groove, 4 is a nozzle, 5 is a film, 6 is a supporting portion, 7 is a measuring groove, and 8 is a nozzle tip edge portion. When the paint is supplied from a supply device (not shown) to the paint reservoir 2 provided inside the block-shaped die 1, the paint is discharged from the nozzle 4 through the flow groove 3. At the nozzle tip portion 4, the film 5 travels in a certain direction at a constant speed while contacting the supporting portion 6. Also, the discharged paint changes the direction by 90 ° at the edge portion 8,
The coating material stored in the measuring groove 7 is transferred to the running film 5, and the stripe coating is completed. Compared to other gravure methods or reverse methods, the die method does not require a scraping and collecting process when measuring the paint, and has excellent stability of paint quality. Further, there is no accident that the coating liquid is scattered and redeposited on the film or the like due to the effect of increasing the centrifugal force of the rotating roll as the coating speed increases. Therefore, it has recently attracted attention as the most reliable and rational method for high-speed coating.

[0003]

However, the above conventional method has the following problems. The coating is applied while the supporting portion 6 is in contact with the film 5 at a certain surface pressure or more, but if the film tension on the supporting portion 6 is weak, the paint will ride on the supporting portion 6 and the end of the stripe coating film. Disorder occurs. At the same time, there is a risk that air particles may be caught due to film pattering. Therefore, as a measure against the above problem, the film tension is increased. Next time,
There is a possibility that the film 5 may be dropped due to a decrease in the liquid pressure due to a slight chipping of the edge portion 8 to cause uneven coating.

The present invention solves the above-mentioned problems of the prior art, and eliminates these factors for the phenomenon of the paint running onto the support portion 6, the air entrainment phenomenon, and the film 5 sagging phenomenon, whereby unevenness of the coating film, etc. An apparatus that can realize uniform and stable stripe coating without defects.

[0005]

To achieve this object, a first invention of the present invention is to provide a block-shaped die main body and a block-shaped upper and lower nozzles provided so as to project from one side surface of the die main body. An opening having a curved surface with a substantially constant curvature provided at the tip of the upper and lower nozzles and a substantially rectangular cross section provided at the tip of either or both of the upper nozzle and the lower nozzle substantially evenly A coating material reservoir provided on the curved surface of the upper nozzle tip portion on the downstream side in the film running direction in a substantially even manner, a flow groove for fluidly connecting the reservoir and the opening, and the upper nozzle. The amount of protrusion to the film side with respect to the lower nozzle is approximately 30 μm or more 5
It has a structure of 60 μm or less.

A second aspect of the present invention has a structure in which an edge portion formed by the opening and the measuring groove has a sharp edge of about 50 μm or less.

[0007]

According to the first aspect of the present invention, by projecting the upper nozzle with respect to the lower nozzle by about 30 μm or more,
By increasing the tension between the support portion and the film, it is possible to prevent the paint from running on the support portion and the entrainment of air particles due to the flapping of the film. Furthermore, it was found that the coating material drips toward the lower nozzle when the protrusion amount is about 60 μm or more.
That is, by optimizing the amount of protrusion of the upper nozzle, stable coating can be realized without accidents such as coating film defects such as entrainment of air particles and paint dripping.

Further, according to the second aspect of the present invention, by making the edge portion a sharp edge of about 50 μm or less, reduction of reduced pressure is prevented, and as a result, unevenness of coating film due to film drop does not occur. An excellent coating film could be obtained.

[0009]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a film, 12a and 12b are tip parts of upper and lower nozzles for supplying paint to the film 11, 13 is paint fed under pressure, 14 is a film contact portion at the nozzle tip part called a support part, Reference numeral 15 is an opening for discharging the paint that has been fed under pressure, 16 is a gap space caused by film patching, and L is a relative position change amount of the upper and lower nozzles.

The operation of this embodiment of the coating apparatus having the above structure will be described in detail with reference to FIG. In this coating apparatus, the film 11 is used from the viewpoint of stable running.
Is required to be about 100 g / cm or less. However, with the above-mentioned tension, the wrapping force around the film 11 around the support portion 14 cannot be said to be sufficient, and when the film 11 is accidentally wrinkled or fluttered, a gap space 16 is formed. In the past, defects such as air entrainment of the coating film due to air entering the gap space and disturbance of the coating film edge portion due to the paint riding on the support portion have occurred. On the other hand, when the amount of wrinkles and the amount of scatter of the film 11 were measured, it was found that the maximum amount reached about 30 μm. From the above experimental examination, the upper nozzle 12a and the lower nozzle 12b are used as means for canceling the film wrinkles and the amount of patter.
In contrast, the protrusion amount is about 30μ
It was decided to make it m or more. However, when the relative protrusion amount reaches 60 μm or more, this time, the coating material starts to drip toward the lower nozzle 12b side and stains the lower nozzle 12b.
When the amount of the contaminated paint on the lower nozzle 12b reaches a certain amount, an accident called reattachment to the film 11 occurs.

From the above viewpoint, the relative amount of protrusion has a proper region of the amount of protrusion of 30 μm or more and 60 μm or less,
It was confirmed that by setting it in that region, stable coating could be performed without air entrainment or disturbance of the coating film edge.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, 21 is a film, 22a and 22b are tip portions of upper and lower nozzles for supplying paint to the film 21, 23 is paint fed under pressure, 24 is a film contact portion of the nozzle tip part called a support portion, 25 Is a supply paint discharge opening, 26 is a paint measuring groove for forming a stripe film, 27 is an edge formed by the opening 25 and the measuring groove 26, and L is the relative position change amount of the upper and lower nozzles.

The operation of the coating apparatus having the above structure will be described below. As described in Example 1, when the relative change amount L of the tip portions of the upper and lower nozzles is projected from the upper nozzle and L is set to 30 μm to 60 μm, the following new problems arise.

In the inside of the measuring groove 26 of FIG. 2, the film 21 has the measuring groove 26 due to the balance between the pressing force of the film 21 against the upper nozzle 22a generated by the tension and the buoyancy of the film 21 caused by the coating liquid pressure. Can be kept in a stable position. However, when the upper nozzle 22a is projected toward the film 21, the projection force is added to the film 21 in addition to the pressing force. At this time, in the portion where the hydraulic pressure is inevitably reduced, that is, the local reduction of the hydraulic pressure due to a minute crack or the like at the edge portion 27, the above influence cannot be ignored and the film 21 develops into a depression. Will end up. Then, the result leads to defective coating unevenness.

In order to avoid the above phenomenon, the edge portion 27
The spec of sharpness was calculated by theoretical analysis. In this phenomenon, it is necessary to consider the equation of motion of the film 21 and the equation of motion of the coating liquid at the same time. Using the levitation analysis code of the film 21 incorporating these equations, changes in the levitation amount of the film 21 and the hydraulic pressure in the measuring groove 26 were calculated using the amount of chipping of the edge portion 27 as a parameter.
The results are shown in FIGS. 3 and 4. As shown in FIG. 3, when the edge chipping amount is 200 μm, the floating amount and the liquid pressure of the film 21 start to change. Further, as shown in FIG. 4, it can be seen that when the amount of chipping is 0.5 mm, the film 21 largely falls and the liquid pressure fluctuates significantly. In addition, the state when the film does not fall is shown by a virtual line.

From the above, the relationship between the chipping of the edge portion 27 and the coating unevenness due to the fall of the film 21 was theoretically clarified, and it became clear that the edge portion should be 200 μm or less. Further, as a result of experiments and examinations with the edges of 50 μm, 100 μm and 200 μm, it was found that the coating unevenness that had occurred at the edges of 100 μm and 200 μm did not occur at the edges of 50 μm at all and succeeded in obtaining a uniform coating. In consideration of safety during mass production, a sharp edge with an edge portion of 50 μm or less was adopted from both the above theory and experiment.

In the first embodiment, the film 11
Although the influence of the unevenness of the pattern is adjusted by the relative protrusion amount, it may be adjusted by increasing the tension of the film 11 or decreasing the radius of curvature of the upper nozzle 12a if possible.

[0020]

According to the first aspect of the present invention, the protrusion amount of the upper nozzle to the film side is about 30 with respect to the lower nozzle.
By providing the structure having a thickness of not less than μm and not more than 60 μm, it is possible to eradicate the cause of the film defect such as the disturbance of the coating film end portion or the air entrainment that has occurred conventionally and to stably obtain a good striped coating film. I can do it.

Further, according to the second aspect of the present invention, the edge portion formed by the opening and the measuring groove has a sharp edge of about 50 μm or less, so that a good coating film free from uneven coating film due to film drop is formed. Could be formed.

[Brief description of drawings]

FIG. 1 is a sectional view of a coating apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a coating device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an analysis result of a flying height of a film.

FIG. 4 is a diagram showing an analysis result of a flying height of a film.

FIG. 5 is a perspective view of a conventional coating device.

[Explanation of symbols]

 11 Films 12a and 12b Top and bottom nozzle tips 13 Paint fed by pressure 14 Supports 15 Openings 16 Gap space L Relative position change amount of top and bottom nozzles

Claims (2)

[Claims] 1. A block-shaped die main body, a block-shaped upper and lower nozzles provided so as to project from one side surface of the die main body, a curved surface having a substantially constant curvature provided at a tip end portion of the upper and lower nozzles, and the upper nozzle. Alternatively, one or both of the lower nozzles has an opening having a substantially rectangular cross section provided substantially evenly at the tip, and the upper nozzle tip curved surface on the downstream side in the film traveling direction is substantially evenly divided. And a measuring groove having a substantially constant depth provided on the die body, a supporting portion and a measuring groove having a substantially constant depth provided on the substantially central portion of the die body, and a substantially central portion of the die body. A paint puddle,
A flow groove that fluidly connects the reservoir and the opening,
A coating apparatus having a configuration in which the amount of protrusion of the upper nozzle toward the film side is 30 μm or more and 60 μm or less with respect to the downward displacement. 2. The edge portion formed by the opening and the measuring groove is 50.
The coating apparatus according to claim 1, which has a sharp edge of not more than μm.