KR102281706B1 - Method for producing coating film and extrusion coating device - Google Patents

Abstract

(assignment)
Provided are a method for producing a coating film and an extrusion coating device that reduce the area of the thickly applied portion of the width direction end of the coating film.
(Solution)
A coating device 10 comprising: a coating liquid discharge port 16A for discharging a coating liquid from a manifold through a slit 16 through which the coating liquid passes; and a spacer 24 for regulating the flow path width of the slit 16; using, the coating liquid discharge port 16A is disposed toward the support 22, and an extrusion coating step of applying the coating liquid to the support is performed, and the coating liquid discharge port side of the spacer 24 has a flow path width It is the extrusion coating apparatus used for the manufacturing method of the application film thickly apply|coated by the width direction edge part in which R shape is formed in the narrowing direction, and a manufacturing method.

Description

The manufacturing method of an application film, and an extrusion coating apparatus TECHNICAL FIELD

The present invention relates to a method for producing a coating film and an extrusion coating device, and in particular, a method for producing a coating film (thickening of the film thickness) in which the width direction edge portion of the coating film is thickly coated and to an extrusion application device.

The extrusion coating device flows the coating liquid supplied to the pocket in the slot die widely from the pocket in the application width direction (same as the web width direction), and a slit having a very narrow gap communicating with the pocket portion. The coating liquid is discharged from the tip. On the other hand, the web (support body) to which the coating liquid is applied forms a bead (coating liquid pool) of the coating liquid discharged from the slit tip in the lip clearance between the slot die tip and the web while being wound around the backup roller and running. , A coating solution is applied to the web via this bead. In addition, the application width|variety of the coating liquid apply|coated to the web is regulated by the distance between the spacers inserted in the both ends of the width direction (the same as the web width direction) of a slit.

In such an extrusion coating device, if a conventional straight tapered spacer tapered toward the inside of the application width is used, the flow rate of the coating liquid at the end of the coating film (near the spacer) due to the viscous shear force is lowered. It became a film thickness distribution in which the part with a thick film thickness at the edge part of a film|membrane spreads, and it was affecting the quality within the effective width of a product.

In order to solve such a subject, for example, in the following patent document 1, in order to prevent an edge part thickening, the coating apparatus which has a shim which has a shape in which the coating liquid flow path gradually widens in the discharge port longitudinal direction is described.

Japanese Patent Laid-Open No. 2000-153199

However, also in the coating apparatus described in patent document 1, it was not able to solve that the area|region of the thickly apply|coated part of the width direction edge part of a coating film spreads.

The present invention has been made in view of such circumstances, and the purpose of providing a method for manufacturing a coating film and an extrusion coating device capable of narrowing the area of the thickly coated portion of the width direction end of the coating film and improving productivity do.

In order to achieve the above object, the present invention is a method for producing a coating film in which a coating liquid is applied on a band-shaped support that travels continuously, and the width direction end of the coating film formed on the support is thickly applied, wherein the coating liquid is An application device comprising: a manifold to be supplied; a coating liquid discharge port for discharging the coating liquid from the manifold through a slit through which the coating liquid passes; and a spacer formed at an end of the slit in the width direction to regulate the flow path width of the slit. using, the coating liquid discharge port is arranged toward the support body, and an extrusion coating step of applying the coating liquid to the support body is carried out, and the coating liquid discharge port side of the spacer is formed in an R shape in the direction in which the flow path width is narrowed. It provides a method for producing a coated film.

The flow velocity near the spacer in the slit is lowered by viscous shear. In the conventional linear spacer, since the channel width gradually narrows, the influence of viscous shear cannot be suppressed, the flow velocity distribution is broadened, and the region of the thickly coated portion is also widened. According to the present invention, since the coating liquid discharge port side of the spacer is formed in an R shape in the direction in which the flow path width becomes narrow, the direction in which the coating liquid flows from the coating liquid discharge port of the slit can be suddenly directed to the inside of the slit. Therefore, since the coating liquid flowing in the vicinity of the spacer can be flowed only to the end of the coating film to be produced, the film thickness can be increased only at the end of the coating film, and the region of the thickly coated portion of the end can be narrowed.

As for the manufacturing method of the coating film which concerns on another embodiment of this invention, it is preferable that the radius of curvature of R shape is 20 mm or more and 100 mm or less.

According to the manufacturing method of the coating film which concerns on another embodiment of this invention, by making the radius of curvature of R shape into the said range, the influence of viscous shear in the vicinity of a spacer can be suppressed, and the area|region of the thickly coated part of the edge part of a coating film can be narrowed.

As for the manufacturing method of the coating film which concerns on another embodiment of this invention, it is preferable that ^{the viscosity of a coating liquid is 0.5 x 10 -3} Pa.s or more and 2 x 10 ^{-2 Pa.s or less.}

According to the manufacturing method of the coating film which concerns on another embodiment of this invention, the viscosity of the coating liquid is low in the said range, and it can implement effectively also about the coating liquid which is easy to be influenced by viscous shear.

In order to achieve the above object, the present invention includes a manifold to which a coating liquid is supplied, a coating liquid discharge port for discharging the coating liquid from the manifold through a slit through which the coating liquid passes, and a slit formed at the end of the slit in the width direction, the slit Provided is an extrusion coating device comprising a spacer for regulating the flow path width of the spacer, and wherein an R-shape is formed on the coating liquid discharge port side of the spacer in a direction in which the flow path width becomes narrower.

According to the present invention, since the coating liquid discharge port side of the spacer is formed in an R shape in the direction in which the flow path width is narrowed, the coating liquid in the vicinity of the spacer can flow only to the end of the coating film to be formed. Therefore, since the area|region of the thickly apply|coated part of the edge part of a coating film can be made narrow, productivity of an application film can be improved.

According to the method for producing a coating film and the extrusion coating device of the present invention, since the coating liquid discharge port side of the spacer to be used is formed in an R shape in the direction in which the flow path width becomes narrower, in the vicinity of the coating liquid discharge port, the flow can be directed toward the end. Therefore, since only the edge part of a coating film can thicken the film thickness, and the thickly apply|coated area|region can be narrowed, productivity can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is the top view which looked at the extrusion application device from above.
2 is a side cross-sectional view of the extrusion application device.
3 is a perspective view of an extrusion application device.
4 is a view showing the shape of a conventional spacer.
Fig. 5 is a diagram showing the shape of a spacer according to the first embodiment.
Fig. 6 is a view showing the film thickness at the end of the coating film produced using the conventional spacer and the spacer of the first embodiment.
Fig. 7 is a diagram of the shape of a spacer according to the second embodiment.
Fig. 8 is a diagram of the shape of a spacer according to the third embodiment.
9 is a view for explaining a spacer used in Examples and Comparative Examples.

EMBODIMENT OF THE INVENTION Hereinafter, according to an accompanying drawing, the manufacturing method of the coating film which concerns on this invention, and preferable embodiment of an extrusion coating apparatus are demonstrated. In addition, in this specification, "-" is used in the meaning which includes the numerical value described before and after that as a lower limit and an upper limit.

<Configuration of Extrusion Applicator>

[First Embodiment]

Fig. 1 is a plan view of an extrusion coating device (hereinafter, simply referred to as "applying device") 10 viewed from above, Fig. 2 is a side cross-sectional view, and Fig. 3 is a perspective view showing the main part.

As shown in these figures, the slot die 12 has a pocket portion 14 inside the head, and a narrow slit 16 communicating with the pocket portion 14 is formed, and the tip of the slit 16 is formed. The coating liquid discharge port 16A is opened in the substantially flat lip surface 18 of the front-end|tip of a head. The openings at both ends through which the pocket portion 14 penetrates are closed by the side plates 30 and 32 formed on both end surfaces of the slot die 12 .

And it is connected to the liquid supply line 31 which penetrates one side plate 32 and sends a coating liquid to the pocket part 14. As shown in FIG. Moreover, as a method of sending the coating liquid to the pocket part 14, in addition to supplying from one side by closing the other end side of the pocket part 14, the type which supplies from the center part of the pocket part 14 and divides it into both sides. , there is a type that supplies from one side of the pocket portion 14 and draws it out from the other direction, and any one may be applied.

1 to 3, the backup roller 20 is disposed adjacent to the lip surface 18 of the slot die 12, and the support (web) 22 to which the coating liquid L is applied is the backup roller 20 ) and supported by being wound around it, it continues to run in the direction of the arrow The gap between the lip surface 18 at the tip of the die and the surface of the support wound on the backup roller 20 is usually set in the range of 30 μm to 300 μm, and the coating thickness, coating speed, and physical properties (viscosity) of the coating liquid L etc.), the bead pressure reduction degree, etc. are appropriately set.

Application|coating of the coating liquid with respect to the support body 22 arrange|positions the support body 22 which is wound around the backup roller 20, and is supported, and continuously travels, and the lip surface 18 of the coating device 10, and apply|coats the coating liquid It is discharged from the coating liquid discharge port 16A of the apparatus 10, and the coating liquid is apply|coated to the support body 22 through the bead formed by bridge|crosslinking between the lip surface 18 and the support body 22. As shown in FIG. When apply|coating a coating liquid, it is preferable to apply|coat a coating liquid by reducing pressure and making it into a negative pressure state from the running direction upstream of a support body rather than an application|coating position. By setting it as a negative pressure state, thinning of the film thickness of a coating film, and suction of accompanying air can be performed. As a pressure reduction degree, it is preferable to exist in the range of -50 Pa - -5000 Pa, More preferably, it exists in the range of -100 Pa - -3000 Pa.

Moreover, as shown in FIG. 1, the application width A of the coating liquid L applied to the support body 22 is a pair inserted in the both ends of the width direction (the same as the support body width direction) of the slit 16. is regulated according to the spacing (distance) between the spacers 24 of In the present invention, it is regulated by the space C between the pair of spacers 24 in the coating liquid discharge port 16A.

Then, the coating liquid supplied to the pocket portion 14 of the slot die 12 expands in the width direction of the support body in the pocket portion 14 and flows, then rises the slit 16 and is discharged from the coating liquid discharge port 16A do. The discharged coating liquid is applied to the support 22 while forming beads between the lip surface 18 of the application head and the support 22 traveling close to the lip surface 18 . That is, the coating liquid is applied to the support in a balanced state between the discharge force of the coating liquid discharged from the coating liquid discharge port 16A at the tip of the slit and the pressing force that the support 22 presses the distal end of the application head. Thereby, an ultra-thin coating film is formed on the surface of a support body.

Here, in this embodiment, the spacer 24 is formed in the width direction edge part of a slit, and regulates the application|coating width apply|coated to a support body. The spacer 24 is formed perpendicular to the support 22 from the manifold side, and on the coating liquid discharge port side of the spacer, an R shape is formed so that the arc of the spacer becomes a concave portion in the direction in which the coating liquid discharge port 16A becomes narrower. has been In addition, as for the starting position of the R shape, the distance from the coating liquid discharge port is preferably equal to or less than the radius of curvature of the R shape, and more preferably equal to the radius of curvature of the R shape. By setting the starting position of the R-shape and the distance from the discharge port to be less than or equal to the radius of curvature of the R-shape, the coating liquid can be flowed more efficiently in the direction of the end of the coating film. In general, the starting position of the R-shape is preferably 5 to 25 mm in distance from the discharge port.

Here, the R-shape indicates a circular arc shape of a perfect circle or an ellipse, but also includes those formed by changing the taper angle step by step in the direction in which the flow path width becomes narrower and thus forming an R-shape as a whole. In addition, the "taper angle" means the angle formed by the extension line of the tapered part of a spacer, and the coating liquid discharge port formed by a pair of spacers. Moreover, an ellipse is preferable from the ease of processing, and a perfect circle is the most preferable.

By forming the coating liquid discharge port side of the spacer 24 in an R shape, even if the flow velocity in the vicinity of the spacer 24 decreases due to the influence of viscous shear at the interface between the spacer 24 and the coating liquid, the application width in FIG. The flow rate of the coating liquid can be made faster from the space|interval (B) of a pair of spacers 24 comrades wider than the application width (A) toward the edge part of (A). Accordingly, the influence of viscous shear at the interface between the spacer 24 and the coating liquid can be suppressed, and the coating liquid can be concentrated at the end, so that the thickly applied width of the coating film can be narrowed.

In addition, in FIGS. 1-3, although demonstrated with the extrusion coating device which has a lip surface on the upstream and downstream sides of a support body running direction, the lip surface is not formed or the lip surface is formed only on the upstream or downstream side. A Trushen applicator may also be used.

Although it does not specifically limit as a support body used by this embodiment, A resin film, a resin plate, a resin sheet, glass, etc. can be used. As a resin film, a polyethylene terephthalate film, a cellulose acetate film, etc. can be used.

Although it does not specifically limit as a coating liquid used by this embodiment, For example, the coating liquid for antireflection films can be used. The viscosity of the coating liquid is not particularly limited, either, but when a low-viscosity coating liquid of 0.5 × 10 ^-3 Pa·s or more and 2 × 10 ^-2 Pa·s or less is used, the film thickness at the end of the coating film tends to become thick. Therefore, by implementing the manufacturing method of this embodiment, the width|variety of the thickly apply|coated part of the coating-film edge part can be made narrow, and it is effective. Moreover, as for the viscosity of a coating liquid, it is more preferable to set it as 0.8x10 ^-3 Pa*s or more and 1x10 ^{-2 Pa*s or less.} In addition, the viscosity of a coating liquid is a numerical value of an extensional viscosity, and can measure with the following method, for example. In addition, the viscosity of a coating liquid is a numerical value of an extensional viscosity, for example, can be measured by a conventional method using a B-type viscometer (Brookfield viscometer).

Next, the shape of the spacer of this embodiment is demonstrated. Fig. 4 is a view showing a conventional tapered spacer. Fig. 5 is a diagram showing an R-shaped spacer according to the first embodiment. Since the flow velocity of the coating liquid is affected by the viscous shear at the interface between the spacer and the coating liquid, the flow velocity of the coating liquid in the vicinity of the spacer is slowed by this viscous shear. As shown in Fig. 4, in the conventional tapered spacer 324, since the tapered portion is long, the coating liquid is concentrated in a wide area at the end of the coating film in the width direction, and the film at the end of the coating film is The thicker part gets wider. Therefore, the thickly coated area is widened, and thus productivity is deteriorated. On the other hand, as shown in FIG. 5 , in the R-shaped spacer 24 of the first embodiment, the coating liquid discharge port side of the spacer is widened in the R-shape. That is, since the flow path width is narrowed just before application|coating, only the edge part of a coating film can speed up the flow rate, and only an edge part can thicken a coating film. Therefore, it is possible to narrow a portion having a thick film at the end of the film, and it is possible to improve productivity.

Fig. 6 is a diagram showing the film thickness of the end portion of the coating film produced using the conventional spacer and the spacer of the first embodiment. As shown in Fig. 6, compared with the coating film formed using the conventional straight tapered spacer, the coating film formed with the tip R-shaped spacer of the first embodiment has a thick film thickness from the end of the coating film. It can be seen that this is narrow.

In addition, the "region of the thickly coated part (thickly applied width)" refers to an edge part having a film thickness of +2% or more with respect to the average value of the film thickness of the coating film in the range of ±0.5% of the application width, including the central portion of the film. means the area from

As a radius of curvature of the R shape of the spacer 24, it is preferable that they are 20 mm or more and 100 mm or less. By making the radius of curvature of the R-shape within the above range, the coating liquid can flow inward in the width direction of the coating film, so that the coating liquid can be applied only in the vicinity of the end portion of the coating film to be produced, and the region of the thickly coated portion can be narrowed.

[Second embodiment]

7 : is a figure which shows the shape of the spacer 124 which concerns on 2nd Embodiment. The spacer 124 shown in FIG. 7 differs from the spacer 24 of the first embodiment in that the radius of curvature of the R-shape is gradually reduced toward the coating liquid discharge port. By reducing the radius of curvature of the R-shape stepwise, the angle between the tangent of the R-shape of the spacer and the coating liquid discharge port can be reduced, so that the coating liquid can flow to the end of the coating film. Therefore, it is possible to flow the coating liquid at a sharp flow rate to the end side of the produced film, and it is possible to narrow the area of the thickly coated portion of the produced film end.

In addition, about the radius of curvature, it is preferable that the radius of curvature of each R-shaped part is in the range of 20 mm or more and 100 mm or less, and by making it smaller in steps within this range, the thickly coated width of the coated film can be narrowed. .

[Third embodiment]

8 is a diagram showing the shape of a spacer 224 according to the third embodiment. The spacer 224 shown in FIG. 8 is different from the spacer 24 of the first embodiment in that the taper angle α is changed stepwise in the direction in which the flow path width becomes narrow toward the coating liquid discharge port. By changing the taper angle stepwise, the same effect as in the case where the coating liquid discharge port side of the spacer has an R shape as in the first and second embodiments can be obtained. Moreover, in 3rd Embodiment, it is preferable to divide and change a taper angle in three or more steps at least.

(Example)

Next, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to this.

[How to apply]

The support, the application head, the application conditions, and the coating liquid used in the Examples are as follows.

As the support, a PET (polyethylene terephthalate) film having a width of 800 mm and a thickness of 15 μm was used.

As the application head, an extrusion type (E-type base) application head having a slit width of 1000 mm, a slit interval of 0.15 mm, and a lip surface length of 350 µm on the upstream side in the support conveyance direction was used.

As the coating liquid, a coating liquid for a low refractive index layer of an antireflection film was used. The refractive index of this coating liquid is 1.42, and MEK-ST (average particle diameter of 10 nm to 20 nm, _{Methyl ethyl ketone dispersion of SiO 2} sol having a solid content concentration of 30 wt %, Nissan Chemical Co., Ltd. 8 g, methyl ethyl ketone 94 g, and cyclohexanone 6 g are added and stirred, followed by stirring, polypropylene having a pore diameter of 1 µm It filtered with a filter made from a product (PPE-01), and the coating liquid for low-refractive-index layers was prepared.

A coating solution is applied to a continuously running support wound around a backup roller and supported by an extrusion type coating head so that the coating width is 700 mm and the dry film thickness is 1 to 20 µm, and then dried to make the coating film was prepared. At the time of application, the film thickness of the produced film end was controlled by changing the radius of curvature of the R-shape of the spacer. Moreover, as a comparative example, the coating film was formed using the conventional tapered spacer.

9 and Table 1 show the types and shapes of spacers used in Examples and Comparative Examples. In the linear tapered spacer, a taper is formed from a position of 50 mm from the coating liquid discharge port, and the angle of the taper is, as shown in Fig. 9(a), the coating liquid discharge port formed by a pair of spacers and The taper was formed so that the angle (alpha) which a taper makes may become Table 1. For the R-shaped spacer, an R-shape was formed with a distance and a width of a radius of curvature R from the coating liquid discharge port (FIG. 9(b)).

[Assessment Methods]

The film thickness of the prepared coated film was measured with an optical interference film thickness meter, and the width (ear width (edge width), thickly coated width) from the application end portion to the top portion (constant film thickness portion) was evaluated. . The width applied thickly was evaluated according to the following criteria.

<Ear width>

A … The thickly coated area from the end is less than 2% of the application width.

B … Thickly coated area from the end is 2% or more but less than 5% of the application width

C … Thickly coated area from the end is 5% or more of the application width

In addition, as described above, the thickly coated region means the region from the edge where the film thickness is +2% or more with respect to the average value of the film thickness of the coating film in the range of ±0.5% of the application width centered on the central portion. do. A result is shown in Table 1.

As shown in Table 1, by using the R-shaped spacer at the tip, compared with the case where the conventional linear tapered spacer was used, the thickly applied width could be narrowed.

10: Extrusion applicator
12: slot die
14: pocket part
16: slit
16A: coating liquid outlet
18: lip side
20: backup roller
22: support (web)
24, 124, 224: spacer
30, 32: side plate
31: liquid remittance line
α: taper angle

Claims (4)

A method for producing a coating film in which a coating liquid is applied on a continuously running band-shaped support, and a width direction edge portion of a coating film formed on the support is thickly applied,
a manifold to which the coating liquid is supplied; a coating liquid discharge port for discharging the coating liquid from the manifold through a slit through which the coating liquid passes; an application step by extrusion coating in which the coating liquid discharge port is disposed toward the support body using a coating device having a spacer to regulate, and the coating liquid is applied to the support body;
An R-shape is formed in the direction in which the width of the flow passage narrows on the coating liquid discharge port side of the spacer,
The viscosity of the coating solution is 0.5 × 10 ^-3 Pa·s or more and 2 × 10 ^-2 Pa·s or less,
The coating solution is a solution containing methyl ethyl ketone as a main component and a fluorinated polymer and silica sol,
The film thickness after drying of the coating liquid applied by the said application|coating process is 1-20 micrometers, the manufacturing method of the coating film. The method of claim 1,
The manufacturing method of the coating film whose radius of curvature of the said R shape is 20 mm or more and 100 mm or less. 3. The method according to claim 1 or 2,
The manufacturing method of the coating film, wherein the radius of curvature of the R-shape becomes small step by step toward the coating liquid discharge port. delete

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