JP2017164682A - Method for manufacturing web with coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a web onto the whole of both sides of which a coating film is applied at a high speed and with a good accuracy.SOLUTION: A method for manufacturing a web with a coating film by which by use of a coating applicator equipped with a coating head having a measuring part provided with a predetermined space and a liquid-storage part for storing a coating liquid above the measuring part, a web, which is transported from an upper side to a lower side in a vertical direction, is passed through the liquid-storage part and the measuring part of the coating head, and the coating liquid is simultaneously applied onto both sides of the web. According to this method, a length h1 from a liquid surface upper end of the coating liquid to a bottom edge of a portion into which the coating liquid is introduced, and a length W of the liquid-storage part in a direction orthogonal to a transported web surface satisfies the relation of W>2×h1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a web with a coating film in which a coating liquid is applied to both surfaces of a film, a nonwoven fabric, paper, or the like.

  The method of applying a coating film on both sides of a web is roughly divided into a sequential application method and a simultaneous application method. However, a sequential application method in which a coating film is applied to each side of a web has a long takt time and production efficiency is low. The simultaneous application method is becoming mainstream.

  The simultaneous coating method is known to perform coating by placing coating heads such as rolls, knives, and slit dies on both sides of the web. Which coating head is selected depends on the nature of the coating liquid to be coated. Or, it is selected in view of the desired thickness accuracy and cost of the coating film.

  As such an application head, Patent Document 1 discloses that a web is passed through a liquid storage part for storing a coating liquid called a dope bath, and then is installed so as to be horizontally opposed in a direction perpendicular to the web surface across the web. An application head that forms a coating film by passing it through a measuring unit called a smoothing jig is disclosed. Patent Document 1 also discloses an application head that forms a coating film by passing between two dies facing each other with a predetermined clearance between webs.

  Further, Patent Document 2 discloses an application head that combines a part consisting of a liquid storage part and a metering part and a slit die in Patent Document 1 in order to simultaneously apply two types of coating materials on both sides. Yes. With this application head, the application to the lower layer in contact with the substrate is carried by the part where the liquid storage part and the measuring part are connected with a gentle inclination, and the application to the upper layer (surface layer) is carried by a part like a slit die. .

JP 2011-12266 A European Patent No. 1270133

  In an application head that forms a coating film on both sides of a web at the same time by passing the liquid storage unit and the metering unit in Patent Document 1 and Patent Document 2, the coating liquid in the vicinity of the web in the liquid storage unit is drawn into the web. The liquid level of the nearby coating liquid decreases. When the lowered liquid level reaches the measuring portion, it causes a coating defect such that the coating film thickness becomes thin or is not coated. In the vicinity of the web, the amount of coating liquid drawn into the web increases as the web conveyance speed during application is increased or the amount to be measured by the measuring unit is increased, that is, the amount applied is increased. The position of the liquid level is further lowered. The lower the liquid level in the vicinity of the web, the easier it is to cause the above-mentioned coating defects or the film breakage of the web due to contact between the web and the metering unit when not applied.

  In order to suppress coating defects due to the liquid level drop in the vicinity of the web, generally, the position where the liquid level of the coating liquid is managed is set higher in the liquid storage part. However, if the liquid surface position of the liquid storage part is too high, the amount of the coating liquid in the coating head increases, the amount of the coating liquid discarded when the coating is finished increases, and the loss of the coating liquid increases. In addition, if the amount of liquid in the liquid storage part increases, the residence time in the liquid storage part until the coating liquid is applied also increases, so depending on the liquid, there is a concern that the composition may change or the material may deteriorate. . Furthermore, since the total weight of the coating head containing the coating liquid increases as the amount of coating liquid in the liquid storage section increases, it is necessary to change the coating head to a rigid structure so that it can withstand it. It is necessary to make the head mounting part strong enough to withstand the increase in weight, leading to an increase in cost.

  As a countermeasure against this, it is conceivable to reduce the length in the width direction of the liquid storage portion orthogonal to the web surface in order to suppress the amount of the coating liquid. However, if the width of the liquid storage part is made too narrow, the amount of liquid applied to the liquid storage part will decrease, and in particular, the liquid application part of the liquid storage part per unit time will increase by increasing the web conveyance speed or increasing the amount of application. When the amount of consumption increases, the liquid level of the coating liquid in the vicinity of the web is easily lowered by being drawn into the web. If it becomes so, it will become easy to cause the defect of application | coating that a liquid level reaches | attains a measurement part and an application | coating film thickness becomes thin or is not apply | coated. In addition, when foreign matter is mixed in the weighing unit, or because the joint between the base material and the base material passes through the weighing unit, the interval between the weighing units that are installed horizontally facing each other with the web interposed between them is temporarily increased. Even when it is necessary to open, if the liquid storage part of the coating head has a narrow width and the amount of liquid in the liquid storage part is small, the liquid level rapidly decreases, leading to coating defects and web breakage.

  In this way, in the method for manufacturing a coated web in which a coating film is simultaneously formed on both sides of the web by passing through the liquid storage unit and the metering unit, the coating amount per unit time is increased by increasing the web conveyance speed. Even when the number is increased, a method for stably coating has not been found.

  Therefore, an object of the present invention is to provide a method for producing a web in which a coating film is applied on both sides of the web simultaneously and at high speed with high accuracy.

  In order to achieve the above object, a method for manufacturing a web with a coating film according to the present invention comprises a coating head having a measuring section provided at a predetermined interval and a liquid storage section for storing a coating liquid above the measuring section. By using the coating apparatus provided, the web transported from the upper side to the lower side in the vertical direction is passed through the liquid storage unit and the measuring unit of the coating head, and the coating liquid is simultaneously coated on both surfaces of the web. When the coating liquid stored in the liquid storage part is drawn downward toward the measuring part by the web to be conveyed, from the liquid surface upper end of the coating liquid to the lower end of the part where the coating liquid is drawn The length h1 and the length W in the direction perpendicular to the web surface to which the liquid storage unit is conveyed are set to satisfy W> 2 × h1.

  Moreover, the manufacturing method of the web with a coating film of this invention makes the said h1 and the liquid level height h2 from the liquid level upper end of the said coating liquid to the minimum of the said liquid storage part satisfy | fill h2> h1. It is preferable.

  According to the present invention, in the manufacture of a coated web in which a coating film is formed on both sides of a web by passing a coating head having a liquid storage section and a metering section, the coating liquid near the web in the liquid storage section is the web. Even if the liquid level of the coating liquid is lowered by being drawn into the liquid, the liquid level does not reach the measuring part, and the web is not broken, and a coating film having a desired thickness is stably formed on both sides. A web with high accuracy can be manufactured.

Schematic which shows the coating device which manufactures a web with a coating film. Schematic sectional view of a coating head used in a coating apparatus for producing a web with a coating

  Preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a coating apparatus for producing a web with a coating film, and FIG. 2 is a schematic sectional view of a coating head used in the coating apparatus. First, a coating apparatus used in the method for producing a coated web according to the present invention will be described.

  A coating apparatus 1 shown in FIG. 1 provided with a coating head 10 shown in FIG. 2 is a coating apparatus that applies a coating liquid 40 to both surfaces of a web 2 to produce a web 20 with a coating film. The configuration of the coating apparatus 1 includes a coating head 10, a liquid level detection unit 3 that detects a liquid level of the coating liquid 40 in the coating head 10, a coating liquid tank 4 that stores a coating liquid supplied to the coating head 10, A pipe 5 that connects the coating liquid tank 4 and the coating head 10, a liquid feed pump 6 that is provided in the middle of the pipe 5 and that feeds the coating liquid to the coating head 10, and a signal from the liquid level detection means 3 are received and sent. It comprises a control unit 7 that instructs operation and stop of the liquid pump 6.

  The coating head 10 shown in FIG. 2 has a measuring unit 11 provided at an interval t in a direction orthogonal to the surface of the web 2 and a liquid storage unit 12 provided above the measuring unit 11. The coating head 10 has a length equal to or greater than the width of the web 2 in the width direction of the web 2, and members 15 and 15 ′ disposed so as to face each other with the web 2 interposed therebetween, and the webs of the members 15 and 15 ′. Is formed of a horizontal plate (not shown) provided so that the coating liquid 40 does not overflow. The interval t in the measuring unit 11 can be freely changed by moving the members 15 and 15 ′ in a direction orthogonal to the web 2 surface by a stage mechanism including a drive source and a guide rail, for example.

  Here, a method of supplying the coating liquid to the coating head 10 will be described. In addition, the liquid level height from the liquid level upper end of the coating liquid 40 in the coating head 10 to the minimum of the liquid storage part 12 is set to h2.

  The supply of the coating liquid to the coating head 10 is based on the fact that the liquid level height h2 has dropped to a liquid level lower limit value (not shown, the same applies hereinafter) of the liquid storage section 12 of the coating head 10 that has been set in advance. If the detection means 3 detects, it will carry out by operating the liquid feeding pump 6 provided in the middle of the piping 5 which leads from the coating liquid tank 4 to the coating head 10 via the control part 7. On the other hand, the supply of the coating liquid 40 is stopped by supplying the coating liquid to the coating head 10 until the liquid level height h2 of the liquid storage unit 12 is set to a liquid level upper limit value (not shown, the same applies hereinafter). When the liquid level detecting means 3 detects that the liquid has risen, the liquid feed pump 6 is stopped via the control unit 7.

  The supply of the coating liquid is not limited to that shown here, for example, using a pressurized coating liquid tank, a pipe connecting the coating liquid tank and the coating head, and a liquid feed valve provided in the middle of the pipe, In response to the result of the liquid level detected by the liquid level detecting means, the liquid supply valve may be opened and closed to supply or stop the coating liquid.

  Next, the production of a coated web performed by applying the coating liquid 40 to the web 2 using the coating apparatus 1 shown in FIG. 1 provided with the coating head 10 shown in FIG. 2 will be described.

  First, before coating, the web 2 is passed between the members 15 and 15 ′ of the facing coating head 10 in advance so that the web 2 passes from the liquid storage unit 12 to the measuring unit 11. Then, the members 15 and 15 ′ of the coating head 10 are moved in the direction perpendicular to the surface of the web 2 to set the interval t of the measuring unit 11 to a desired interval, and then the coating liquid is fed from the coating liquid tank 4 by the liquid feed pump 6. The liquid is supplied to and stored in the liquid storage section 12 of the coating head 10. The liquid level height h2 from the upper end of the liquid level of the coating liquid 40 in the coating head 10 to the lower limit of the liquid storage unit 12 at this time is a preset upper limit value of the liquid level. Then, the web 2 is transported from the vertically upper side to the lower side of the coating head 10 so that the web 2 passes through the measuring unit 11 from the liquid storage unit 12 of the coating head 10, and the coating liquid 40 is applied to both surfaces of the web 2. The coated web 20 is manufactured by coating. At this time, the application amount of the coating liquid to the coated web 20 is determined only by the interval t of the measuring unit 11, regardless of the transport speed.

  And if application | coating is continued as it is, since the coating liquid 40 will be apply | coated continuously to the web 2 and the web 20 with a coating film will be manufactured, the coating liquid 40 of the liquid storage part 12 will reduce gradually, and it sets beforehand in advance. The liquid level height h2 is lowered to the liquid level lower limit value. Then, the liquid level detecting means 3 detects this, and the liquid feed pump 6 provided in the middle of the pipe 5 leading from the coating liquid tank 4 to the coating head 10 is operated, and the coating liquid is supplied to the liquid storage section 12. Supply. And if the liquid level detection means 3 detects the preset liquid level upper limit of the liquid level height h2 of the liquid storage part 12, the liquid feeding pump 6 will be stopped and supply of a coating liquid will be stopped. Thereafter, as long as the application is continued, the coating liquid is supplied when the liquid level lower limit value is detected, and the supply of the coating liquid is stopped when the liquid level upper limit value is detected.

  Here, the liquid level detection means 3 may be any means, but does not inhibit the conveyance of the web 2 or the flow of the coating liquid 40 in the coating head 10, and also prevents foreign matter from entering the coating liquid 40. Since it can do, the means which detects a liquid level non-contactingly is preferable.

  Next, the aspect of the measurement part 11 and the liquid storage part 12 of the coating head 10 when manufacturing the coated film web 20 will be described in more detail with reference to FIG.

  While manufacturing the web 20 with a coating film, the web 2 is first transported from the vertically upper side to the lower side of the coating head 10 and enters the liquid storage part 12 of the coating head 10. At this time, the liquid level of the coating liquid 40 in the liquid storage unit 12 is drawn into the web 2 that is transported vertically downward, and decreases as the distance from the web 2 approaches the web. Draw an arc toward the web 2. The shape of the arc varies depending on the viscosity of the coating liquid 40, the conveyance speed of the web 2 to be conveyed, and the length of the liquid storage section 12 in the direction orthogonal to the web 2 surface.

  Here, the distance from the liquid surface upper end of the coating liquid 40 of the liquid storage part 12 being applied to the lower end drawn into the web is h1, and the length of the liquid storage part 12 in the direction perpendicular to the web 2 surface being conveyed is When W is set, W and h1 are set to satisfy the relationship of W> 2 × h1.

  The shape of the liquid surface drawn by the web 2 drawing the coating liquid 40 draws an arc shape similar to a part of the circumference. Therefore, the liquid level within a range of h1 from the web 2 is inclined in a direction parallel to the direction orthogonal to the web 2 surface as it approaches the web 2. It means that you are drawn into. The distance between the web 2 and the member 15 or the distance between the web 2 and the member 15 ′, that is, the half of the length W of the liquid storage section 12 in the direction orthogonal to the surface of the web 2 is smaller than h1. The liquid level of the coating liquid 40 is all inclined toward the web 2, and this is because sufficient coating liquid 40 is not secured to measure by the measuring unit 11, so that the drawing of the coating liquid 40 becomes strong. It may indicate that there is a possibility. If the weighing unit 11 cannot perform proper weighing, the coating film thickness is not stable on the web 2 in the coating direction, and there is a possibility of causing a coating defect such that the coating film becomes thin or not coated. In order to obtain a stable coating film, the relationship of W> 2 × h1 is satisfied.

  Next, when the liquid level height from the upper end of the liquid level of the coating liquid 40 to the lower limit of the liquid storage unit 12 is h2, it is preferable that h2> h1 is satisfied.

  When h1 which is the drawing-in height exceeds h2, this means that the lower end of the liquid level has reached the measuring unit 11, and the coating liquid to be applied is changed by changing the amount of the coating liquid 40 in the measuring unit 11. It is preferable that h2> h1 is satisfied because the amount of the coating liquid 40 is reduced and the applied coating liquid 40 causes film breakage on the web 2.

  As described above, if the method for producing a web with a coating film according to the present invention is used, a web with a coating film having a uniform film thickness can be accurately produced.

  The present invention can be applied to a method for producing a web such as paper, a metal thin film, a film, or a cloth having a coating film on both sides simultaneously, but is not limited thereto.

DESCRIPTION OF SYMBOLS 1 Application | coating apparatus 2 Web 3 Liquid level detection means 4 Coating liquid tank 5 Piping 6 Liquid feed pump 7 Control part 10 Application | coating head 11 Measuring part 12 Liquid storage part 15, 15 'Member 20 Web with coating film 40 Coating liquid h1 of coating liquid Length from the upper end of the liquid surface to the lower end of the portion where the coating liquid is drawn in. H2 Liquid surface height from the upper end of the liquid surface of the coating liquid to the lower limit of the liquid storage part. W The direction orthogonal to the web surface of the liquid storage part being conveyed. Length t The distance between the measuring parts 11 in the direction perpendicular to the web surface

Claims (2)

Using a coating apparatus having a coating head having a weighing unit provided at a predetermined interval and a liquid storage unit for storing a coating liquid above the weighing unit, the coating unit is transported from the upper side to the lower side in the vertical direction. A method for producing a web with a coating, wherein a web is passed through the liquid storage part and the metering part of the application head, and a coating liquid is simultaneously applied to both sides of the web,
The length from the upper end of the liquid surface of the coating liquid to the lower end of the portion where the coating liquid is drawn when the coating liquid stored in the liquid storage section is drawn downward toward the measuring section by the web to be conveyed. The manufacturing method of the web with a coating film which makes h1 and length W of the direction orthogonal to the web surface conveyed of the said liquid storage part satisfy | fill W> 2xh1.   The method for producing a web with a coating film according to claim 1, wherein the h1 and the liquid level height h2 from the upper end of the liquid level of the coating liquid to the lower limit of the liquid storage part satisfy h2> h1.

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