TW201536415A - Manufacturing method of coating film and extrusion coating apparatus - Google Patents

Abstract

The subject of the present invention is to provide a manufacturing method of coating film and an extrusion coating apparatus, which can reduce the area of a thin coating portion at an end part of the coating film in the width direction. To solve the problem, the present invention provides a manufacturing method of coating film in which the end part in the width direction becomes a thin coating, and also provides an extrusion coating apparatus used in the manufacturing method. The manufacturing method includes a coating step of extrusion coating for using a coating apparatus 10 and orienting the coating liquid ejection port 16A toward the support body 22 to coat the coating liquid onto the support body. The coating apparatus 10 comprises: a coating liquid ejection port 16A to eject coating liquid from a manifold and through a slit 16, and a spacer 24 for regulating the flow path width of the slit 16, wherein the spacer 24 at the side of the coating liquid ejection port is provided with an R shape in a direction along which the flow path width is increased.

Description

Coating film manufacturing method and extrusion coating device

The present invention relates to a method for producing a coated film and an extrusion coating device, and more particularly to a method for producing a coating film in which a width direction end portion of a coating film is thinned (thickness is reduced) and an extrusion coating device.

The extrusion coating apparatus spreads the coating liquid supplied to the pocket portion in the slot die in a pocket in the coating width direction (the same as the width direction of the web). Spread), the coating liquid is ejected from a slit end having a narrow gap that communicates with the pocket portion. On the other hand, the mesh (support) of the coating liquid to be applied is wound around a backup roller, and a lip clearance between the front end of the slit die and the mesh has been formed. The coating liquid of the coating liquid discharged from the tip end of the slit (reservoir of coating fluid) is passed through the beads to apply the coating liquid to the mesh. Moreover, the application width of the coating liquid applied to the mesh is regulated by the distance between the spacers which are inserted in the slit width direction (the same as the width direction of the mesh).

In the above-described extrusion coating apparatus, when the conventional linear tapered spacer is used, the thickness of the thin portion of the film thickness due to the viscous shearing force is broadened at the end portion, and the thickness is thin within the effective width of the product. Painted, so it has an impact on quality.

In order to solve such a problem, for example, Patent Document 1 listed below discloses a slit die coater nozzle which is used for forming a slit for the purpose of coating with a uniform film thickness. The side surface of the opening is curved in a curved shape on the outer side.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-864

However, in the nozzle die coater nozzle described in Patent Document 1, the film thickness at the end portion in the width direction of the coating film cannot be released, and the thin coating portion is also wide.

The present invention has been made in view of such circumstances, and an object of the invention is to provide a method for producing a coated film and an extrusion coating device which can reduce the area of the thin portion of the end portion in the width direction of the coating film, thereby improving productivity.

In order to achieve the above object, the present invention provides a method for producing a coated film by coating a coating liquid on a continuously traveling belt-shaped support, and the end portion in the width direction of the coating film formed on the support is thinly coated. The method for producing a coated film includes a coating step by extrusion coating, wherein a coating liquid discharge port is disposed toward a support body using a coating device, and a coating liquid is applied to the support; the coating device is provided with a coating liquid supplied thereto a tube, a coating liquid discharge port that ejects a coating liquid from a manifold through a slit through which a coating liquid passes, and is disposed at a slit width direction end And a spacer which regulates the flow path width of the slit; and the coating liquid discharge port side of the spacer is formed in an R shape in a direction in which the flow path width is widened.

The flow rate near the wall of the spacer is reduced by viscous shear. In the conventional linear spacer, since the flow path width is gradually widened, the influence of the viscous shear cannot be suppressed, and the flow velocity distribution is widened, and the area of the thin coating portion is also widened. According to the invention, since the coating liquid discharge port side of the spacer is formed in the R shape in the direction in which the flow path width is widened, the coating liquid can be caused to flow to the end direction of the formed coating film, and the adhesiveness can be suppressed. The effect of shearing. Therefore, only the flow rate of the coating liquid in the slit corresponding to the vicinity of the end portion of the applied coating film can be lowered, and only the film thickness in the vicinity of the end portion of the coating film can be made thin. That is, since the thin coating width of the end portion of the coating film can be made small, the productivity of the coating film can be improved.

In the method for producing a coated film according to another embodiment of the present invention, it is preferable that the radius of curvature of the R shape is 20 mm or more and 100 mm or less.

According to the method for producing a coated film according to another embodiment of the present invention, by setting the radius of curvature of the R shape to the above range, the influence of the viscous shear in the vicinity of the spacer can be suppressed, and the end portion of the coating film can be made thin. The area where the part is painted.

In the method for producing a coated film according to another embodiment of the present invention, the viscosity of the coating liquid is preferably 0.5 × 10 ^-3 Pa‧s or more and 2 × 10 ^-2 Pa‧s or less.

According to the method for producing a coated film according to another embodiment of the present invention, even if the viscosity of the coating liquid is within the above range, the coating liquid having a low viscosity and being easily affected by viscous shear can be effectively carried out.

In order to achieve the above object, the present invention provides an extrusion coating apparatus comprising: a manifold for supplying a coating liquid; a coating liquid discharge port for discharging a coating liquid from a manifold through a slit through which the coating liquid passes; The spacer at the width direction end portion and the flow path width of the slit is adjusted, and the coating liquid discharge port side of the spacer is formed in an R shape in a direction in which the flow path width is widened.

According to the invention, since the coating liquid discharge port side of the spacer is formed in the R shape in the direction in which the flow path width is widened, the liquid can flow to the end direction of the formed coating film, and the viscous shear can be pressed. The impact of the cut. Therefore, only the flow rate of the coating liquid in the slit corresponding to the vicinity of the end portion of the coated film to be produced can be lowered, and only the film thickness in the vicinity of the end portion of the coating film can be made thin. In other words, the productivity of the coated film can be improved by reducing the thin coating width of the end portion of the coating film.

According to the method for producing a coated film of the present invention and the extrusion coating apparatus, the spacer used is formed in an R shape in a direction in which the flow path width is widened, and the flow velocity distribution in the vicinity of the coatable liquid discharge port is directed toward the end portion in the width direction. Only reduce the flow rate at the end in the width direction (near the spacer). Therefore, the thin coating width at the end portion in the width direction can be reduced, and the productivity can be improved.

10‧‧‧Extrusion coating device

12‧‧‧Slit mould

14‧‧‧ Pocket Department

16‧‧‧Slit

16A‧‧‧ Coating liquid discharge

18‧‧‧Lip face

20‧‧‧Support roller

22‧‧‧ mesh (support)

24‧‧‧ spacers

30, 32‧‧‧ side panels

31‧‧‧ Liquid supply line

‧‧‧‧ cone angle

[Fig. 1] is a plan view of the extrusion coating apparatus as seen from above.

[Fig. 2] is a side cross-sectional view of the extrusion coating apparatus.

[Fig. 3] is a perspective view of an extrusion coating apparatus.

[Fig. 4] is a view showing the shape (a) of the previous spacer and the film thickness (b) of the film end portion produced.

[Fig. 5] A view showing the shape (a) of the spacer of the first embodiment and the film thickness (b) of the film end portion produced.

Fig. 6 is a view showing the shape of the spacer of the second embodiment.

Fig. 7 is a view showing the shape of a spacer according to a third embodiment.

[Fig. 8] A view illustrating a spacer used in the examples and comparative examples.

[Formation of the Invention]

Hereinafter, preferred embodiments of a method for producing a coated film and an extrusion coating device according to the present invention will be described with reference to the accompanying drawings. In the present specification, the term "~" is used to mean that the numerical values described before and after are used as the lower limit value and the upper limit value.

<Structure of extrusion coating device>

[First Embodiment]

Fig. 1 is a plan view of an extrusion coating apparatus (hereinafter, also simply referred to as "coating apparatus") 10 as seen from above, Fig. 2 is a side sectional view, and Fig. 3 is a perspective view showing a main part.

As shown in the figures, the slit die 12 has a pocket portion 14 formed therein and a narrow slit 16 communicating with the pocket portion 14, and the coating liquid discharge port 16A at the tip end of the slit 16 is attached thereto. The generally flat lip surface 18 of the front end of the head is opened. The opening portions at both ends of the through pocket portion 14 are blocked by the side plates 30 and 32 provided on both end faces of the slit die 12.

Then, one of the side plates 32 is passed through to the liquid supply line 31 that sends the coating liquid to the pocket portion 14. In addition, the method of feeding the coating liquid to the pocket portion 14 is supplied from one side of the pocket portion 14 in addition to the other end side of the clogging pocket portion 14, and is branched to two. Any type of side type, a type that is supplied from one side of the pocket portion 14 and extracted from the other direction can be applied.

In the first to third figures, the backup roller 20 is disposed adjacent to the lip surface 18 of the slit die 12, and the mesh (support) 22 of the coating liquid L is wound around the support roller 20 to be supported by the arrow. The direction continues to travel. The gap between the lip surface 18 of the front end of the mold and the surface of the web wound on the backup roll 20 is usually set in the range of 30 μm to 300 μm, depending on the coating thickness, the coating speed, the physical properties (viscosity, etc.) of the coating liquid L, and the bead reduction. It is set as appropriate in terms of reduction in bead pressure or the like.

The application of the coating liquid to the web 22 is carried out by winding the web 22 which is continuously supported by the support roller 20 and is placed close to the lip surface 18 of the coating device 10, and is ejected and coated from the coating liquid discharge port 16A of the coating device 10. The liquid is applied to the web 22 through a bead formed by crosslinking between the lip surface 18 and the web 22. When the coating liquid is applied, it is preferred to apply a coating liquid by performing a pressure reduction to a negative pressure state from the coating position to the upstream side in the traveling direction of the web. By making the work into a negative pressure state, it is possible to form a thin film of the coating film thickness, adjust the thickness of the coating film, and attract the air. The degree of decompression is preferably in the range of from -50 Pa to -5000 Pa, more preferably in the range of from -100 Pa to -3000 Pa.

Moreover, the application width A of the coating liquid L applied to the mesh sheet 22 is inserted into the width direction of the slit 16 as shown in Fig. 1 . One of the both end portions (the same as the width direction of the mesh) is regulated by the interval (distance) B between the spacers 24.

Then, the coating liquid supplied to the pocket portion 14 of the slit die 12 is expanded in the width direction of the mesh portion of the pocket portion 14, and then the slit 16 is raised to be ejected from the coating liquid discharge port 16A. The sprayed coating liquid is applied to the mesh sheet 22 while forming a bead between the lip surface 18 of the coating head and the web 22 that travels close to the lip surface 18. In other words, the coating liquid is applied to the mesh in a state where the discharge force of the coating liquid discharged from the coating liquid discharge port 16A at the tip end of the slit is balanced with the pressing force of the web 22 at the tip end portion of the coating head. Thereby, an extremely thin coating film is formed on the mesh surface.

Here, in the present embodiment, the spacer 24 is provided at the end portion in the width direction of the slit, and regulates the coating width applied to the support. The spacer 24 is formed perpendicularly to the mesh sheet 22 from the manifold side, and the coating liquid discharge port side is formed in an R shape in a direction in which the coating liquid discharge port 16A is widened. Further, the starting position of the R shape is preferably equal to or less than the radius of curvature of the R shape from the coating liquid discharge port, and more preferably equal to the radius of curvature of the R shape. By setting the starting position of the R shape to be equal to or less than the radius of curvature of the R shape from the discharge port, the coating liquid can be more efficiently flowed to the end direction of the coating film. In general, the starting position of the R shape is preferably 5 to 25 mm from the discharge port.

Here, the R shape means an arc shape of a perfect circle or an ellipse, but it also includes a case where the taper angle is changed stepwise in the direction in which the flow path width is widened, and the R shape is formed as a whole. Moreover, the "tapered angle" is an extension of the tapered portion of the spacer and is formed by a pair of spacers. The angle formed by the spray outlet of the coating liquid. Further, from the viewpoint of easiness of processing, it is preferably an ellipse, and the best is a perfect circle.

By forming the coating liquid discharge port side of the spacer 24 into an R shape and pressing the influence of the viscous shear at the interface between the spacer 24 and the coating liquid, it is possible to apply only the coating liquid at the end portion in the width direction of the coating liquid discharge port 16A. The flow rate is reduced. Thereby, the thin coating width of the coating film can be reduced.

In addition, in the first to third figures, the extrusion coating device having the lip surface on the upstream side and the downstream side in the web traveling direction is described, but it is also possible to use the non-lip surface or only on the upstream side or The downstream side is provided with a lip coating device.

The mesh (support) used in the present embodiment is not particularly limited, but a resin film, a resin plate, a resin sheet, glass, or the like can be used. As the resin film, a polyethylene terephthalate film, a cellulose acetate film, or the like can be used.

The coating liquid used in the present embodiment is not particularly limited, and for example, a coating liquid for an antireflection film can be used. The viscosity of the coating liquid is not particularly limited, 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 end of the coating film is used. Since the film thickness is easily thinned, it is effective to reduce the width of the thin portion of the coating film at the end portion of the coating film by performing the production method of the present embodiment. Further, the viscosity of the coating liquid is preferably 0.8 × 10 ^-3 Pa‧s or more and 1 × 10 ^-2 Pa‧s or less. Further, the viscosity of the coating liquid is a value of the elongational viscosity, and can be measured, for example, by a conventional method using a B-type viscometer (Brookfield viscometer).

Next, the shape of the spacer of the embodiment is performed. Description. Fig. 4 is a view (b) of the previous tapered shape of the spacer (a) and a film thickness showing the film end portion produced using the spacer. Fig. 5 is a view showing the R-shaped spacer (a) of the first embodiment and the thickness (b) showing the film thickness of the film end portion produced by using the spacer. The flow rate of the coating liquid is affected by the viscous shear in the interface between the spacer and the coating liquid, and the flow velocity of the coating liquid in the vicinity of the spacer is slowed by the viscous shear. As shown in Fig. 4(a), in the case of the spacer member 324 of the previous tapered shape, since the portion of the tapered shape is long, the region where the flow velocity of the coating liquid becomes slow with respect to the width direction becomes wider; As shown in Fig. 4(b), the film thickness portion (thin coating width) of the film end portion is widened, and the productivity is deteriorated. On the other hand, as shown in Fig. 5(a), in the R-shaped spacer 24 of the first embodiment, since the flow path is expanded to the R shape immediately before the application of the coating liquid, the viscous shear can be pressed. The effect of cutting in the width direction is cut, and the area where the flow velocity is slow can be reduced. Therefore, as shown in Fig. 5(b), the thin portion of the film end portion becomes small, and the productivity can be improved.

In addition, the "thickness of the film thickness at the end of the film (thin coating width)" is an average value of the film thickness of the coating film in the range of ±0.5% of the coating width in the center portion of the film, and the film thickness is 98% or less. The area from the end.

The radius of curvature of the R shape of the spacer 24 is preferably 20 mm or more and 100 mm or less. By setting the radius of curvature of the R shape to the above range, the coating liquid can be caused to flow in the width direction of the coating film, and the region of the thin portion of the end portion of the applied coating film can be reduced.

[Second Embodiment]

Fig. 6 is a view showing the shape of the spacer 124 according to the second embodiment. The spacer 124 shown in Fig. 6 is different 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 gradually reducing the radius of curvature of the R shape stepwise, the angle formed by the spacer and the coating liquid discharge port can be made small, and the coating liquid can be caused to flow in the width direction. Thereby, the coating liquid can be caused to flow to the end side of the produced film, and the area of the thin portion of the film end to be produced can be reduced.

In addition, the radius of curvature of the portion of each R shape may be in the range of 20 mm or more and 100 mm or less with respect to the radius of curvature, and the thickness of the coating film can be reduced by a stepwise reduction in the range.

[Third embodiment]

Fig. 7 is a view showing the shape of the spacer 224 according to the third embodiment. The spacer 224 shown in Fig. 7 is different from the spacer 24 of the first embodiment in that the taper angle α is gradually changed in the direction in which the width of the flow path is widened toward the coating liquid discharge port. By the stepwise change of the taper angle, the same effect as in the case where the coating liquid discharge port side of the separator is set to the R shape in the first and second embodiments can be obtained. Further, in the third embodiment, the taper angle is preferably changed to at least three stages or more.

[Examples]

Next, the present invention will be specifically described by way of examples, but the invention is not limited thereto.

[Coating method]

The mesh, the coating head, the coating conditions, and the coating liquid used in the examples are as follows.

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

An application head of an extrusion type (E-type geeser) 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 web conveyance direction was used for the coating head.

As the coating liquid, a coating liquid for a low refractive index layer of an antireflection film was used. The coating liquid had a refractive index of 1.42, and MEK-ST (average particle) was added to 93% of a methyl ethyl ketone solution (JN-7228, manufactured by JSR) of a 6% by weight of a thermally crosslinkable fluoropolymer. 10 nm to 20 nm, a methyl ethyl ketone dispersion of SiO ₂ sol having a solid concentration of 30% by weight, 8 g of Nissan Chemical Co., Ltd., 94 g of methyl ethyl ketone and 6 g of cyclohexanone, and agglutination after stirring A 1 μm polypropylene filter (PPE-01) was filtered to prepare a coating liquid for a low refractive index layer.

The coating liquid was applied to the web which was continuously supported by the support roll, and the coating liquid was applied so as to have a coating width of 700 mm and a dry film thickness of 1 to 20 μm, and dried to produce a coated film. At the time of coating, the film thickness of the end portion of the film to be produced was controlled by changing the radius of curvature of the R shape of the spacer. Further, as a comparative example, a coating film was formed using a spacer having a tapered shape in the past.

The types and shapes of the spacers to be used in the examples and comparative examples are shown in Fig. 8 and Table 1. In the linear trapezoidal spacer, a taper is provided at a position 50 mm from the discharge opening of the coating liquid, and the angle of the taper is formed by a pair of spacers as shown in Fig. 8(a). Coating The angle (α) between the liquid discharge port and the taper was set to be tapered as shown in Table 1. The R-shaped spacer is formed into an R shape by a distance and a width from the coating liquid discharge opening with a radius of curvature R (Fig. 8(b)).

[Evaluation method]

The film thickness of the produced coating film was measured by an optical interference layer thickness meter, and the width (edge width (edge width) from the coated end portion to the fixed portion (a certain film thickness portion) ), thin coating width) for evaluation. The thin coating width was evaluated on the basis of the following criteria.

<thin coating width>

A. . . The thin coating area from the end is less than 2% of the coating width

B. . . The coating area from the end is 2% or more of the coating width less than 5%

C. . . 5% or more of the coating width from the end portion of the thin coating area

In addition, as described above, the thin coating region has a film thickness of 98% or less from the end portion with respect to the average value of the coating film thickness in the range of ±0.5% in the application width centering on the center portion. The results are shown in Table 1.

As shown in Table 1, the thin coating width can be reduced by using the spacer of the front end R shape as compared with the case of using the spacer of the previous linear tapered shape.

24‧‧‧ spacers

Claims (4)

A method for producing a coated film, which is a method for producing a coated film by coating a coating liquid on a continuously traveling belt-shaped support, and forming a coating film formed on the support in a width direction direction; There is a coating step by extrusion coating: a coating liquid discharge port is disposed toward the support body using a coating device, and the coating liquid is applied to the support body; wherein the coating device is provided with: the coating liquid is supplied a pipe, a coating liquid discharge port through which the coating liquid passes through the slit through which the coating liquid passes, and a spacer provided at an end portion of the slit in the width direction and regulating a flow path width of the slit The coating liquid discharge port side of the spacer is formed in an R shape in a direction in which the flow path width is widened. The method for producing a coated film according to claim 1, wherein the radius of curvature of the R shape is 20 mm or more and 100 mm or less. The method for producing a coated film according to claim 1 or 2, wherein the viscosity of the coating liquid is 0.5 × 10 ^-3 Pa‧s or more and 2 × 10 ^-2 Pa‧s or less. An extrusion coating apparatus comprising: a manifold to which a coating liquid is supplied; a coating liquid discharge port through which a coating liquid passes through the slit through which the coating liquid passes, and a width of the slit in the width direction of the slit A spacer that regulates the flow path width of the slit at the end portion; and the coating liquid discharge port side of the spacer is formed in an R shape in a direction in which the flow path width is widened.