TW201536416A - 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 thick 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 thick 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 apparatus, and more particularly to a method for producing a coating film in which a width direction of a coating film is thick (thickness is increased) and an extrusion coating apparatus.

The extrusion coating apparatus is such that the coating liquid supplied to the pocket in the slot die is widened in the pocket width in the coating width direction (the same as the web width direction) (wide 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 applied coating liquid is wound around a backup roller, and a lip clearance between the front end of the slit die and the mesh has been formed. A bead (reservoir of coating fluid) of the coating liquid discharged from the tip end of the slit is passed through the bead 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).

With such an extrusion coating apparatus, if a previous linear tapered shape spacer having a tapered shape toward the inner side of the coating width is used, the flow rate of the coating liquid at the end portion (near the spacer) of the coating film is viscous shear The thickness is reduced by the shear force, so it becomes a thick portion of the film thickness at the end of the coating film. A widened film thickness distribution affects the quality within the effective width of the article.

In order to solve such a problem, for example, Patent Document 1 discloses a coating device which has a shape in which the coating liquid flow path is gradually widened in the longitudinal direction of the discharge port in order to prevent the thickness of the end portion.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2000-153199

However, even in the coating device described in Patent Document 1, the region where the thick portion of the coating film in the width direction end portion is not released is widened.

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 apparatus which can reduce the area of the thick portion of the coating film in the width direction and improve the productivity.

In order to achieve the above object, the present invention provides a method for producing a coated film by applying a coating liquid on a belt-shaped support that continuously travels, and the end portion in the width direction of the coating film formed on the support is thickly coated. A method for producing a coated film comprising a coating step by extrusion coating, wherein a coating liquid discharge port is disposed toward a support using a coating device, and a coating liquid is applied to the support; the coating device includes: a manifold for supplying a coating liquid, a coating liquid discharge port through which a coating liquid passes through a slit through which the coating liquid passes, and a spacer which is provided at an end portion in the width direction of the slit and which regulates a flow path width of the slit; Further, the coating liquid discharge port side of the separator is formed in an R shape in a direction in which the flow path width is narrowed.

The flow velocity near the spacer of the slit is reduced by viscous shear. In the conventional linear spacer, since the width of the flow path is gradually narrowed, the influence of the viscous shear cannot be suppressed, and the flow velocity distribution is broadened, and the area of the thick coated portion is also widened. According to the present 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 narrowed, the flow direction of the coating liquid can be sharply directed toward the slit at the coating liquid discharge port of the slit. The inside. Therefore, since the coating liquid flowing in the vicinity of the separator can flow only to the end portion of the coating film to be produced, the film thickness of the end portion of the coating film can be increased, and the area of the thick portion of the end portion can be reduced. .

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 thickness of the end portion of the coating film can be reduced. 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 another aspect of the present invention, in the method for producing a coated film, the viscosity of the coating liquid is low in the above range, The coating liquid which is easily affected by the viscous shear can also 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 narrowed.

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 narrowed, the coating liquid in the vicinity of the spacer can flow only to the end portion of the formed coating film. Therefore, the productivity of the coating film can be improved by reducing the area of the thick portion of the end portion of the coating film.

According to the method for producing a coating film of the present invention and the extrusion coating apparatus, the coating liquid discharge port side of the separator to be used is formed in the R shape in the direction in which the flow path width is narrowed, and is capable of being formed in the vicinity of the coating liquid discharge port. The flow is directed towards the end. Therefore, productivity can be improved because only the thickness of the end portion of the coating film can be increased and the thick coating region can be reduced.

10‧‧‧Extrusion coating device

12‧‧‧Slit mould

14‧‧‧ Pocket Department

16‧‧‧Slit

16A‧‧‧ Coating liquid discharge

18‧‧‧Lip face

20‧‧‧Support roller

22‧‧‧Support (mesh)

24, 124, 224‧‧‧ 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 of the previous spacer.

Fig. 5 is a view showing the shape of the spacer of the first embodiment.

[Fig. 6] Fig. 6 is a view showing the film thickness of the end portion of the coating film produced by using the spacer of the prior spacer and the spacer of the first embodiment.

Fig. 7 is a view showing the shape of the spacer of the second embodiment.

Fig. 8 is a view showing the shape of a spacer according to a third embodiment.

[Fig. 9] A view illustrating a spacer used in the examples and comparative examples.

[Formation of the Invention]

Hereinafter, preferred embodiments of the method for producing a coated film and the extrusion coating device of 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 is formed with a pocket portion 14 inside the head 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 to the head. The generally flat lip surface 18 of the front end 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. Furthermore, the coating liquid will be The method of feeding to the pocket portion 14 is performed by supplying the side portion of the pocket portion 14 from the center portion of the pocket portion 14 in addition to the other end side of the pocket portion 14, and the type is removed from the pocket portion. Any of the types in which one of the 14 is supplied and extracted from the other direction can be applied.

In the first to third figures, the backup roller 20 is disposed close to the lip surface 18 of the slit die 12, and the support (mesh) 22 to which the coating liquid L is applied is wound around the support roller 20 to be supported in the direction of the arrow. Travel continuously. The gap between the lip surface 18 of the front end of the mold and the surface of the support that has been wound around 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 support body 22 is performed by winding the support body 22 which is continuously supported by the support roller 20 and supported, and is disposed close to the lip surface 18 of the coating device 10, and is sprayed and coated from the coating liquid discharge port 16A of the coating device 10. The liquid is applied to the support 22 by a bead formed by crosslinking between the lip surface 18 and the support 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 on the upstream side in the traveling direction of the support. By the negative pressure state, it is possible to form a film thickness of the coating film and to attract air. The degree of decompression is preferably in the range of -50 Pa to -5000 Pa, more preferably in the range of -100 Pa to -3000 Pa.

Moreover, as shown in FIG. 1, the application width A of the coating liquid L applied to the support 22 is one of the two end portions which are inserted in the width direction of the slit 16 (the same as the width direction of the support). The spacers 24 are controlled by the spacing (distance) of each other. In the present invention, by spraying in a coating liquid One of the outlets 16A regulates the spacing C of the spacers 24 from one another.

Then, the coating liquid supplied to the pocket portion 14 of the slit die 12 is expanded in the width direction of the support body after the pocket portion 14 is expanded in the width direction of the support, and then the slit 16 is raised and discharged from the coating liquid discharge port 16A. The sprayed coating liquid is applied to the support 22 while forming a bead between the lip surface 18 of the coating head and the support 22 that travels close to the lip surface 18. In other words, the coating liquid is applied to the support 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 support body 22 pressing the tip end portion of the coating head. Thereby, an extremely thin coating film is formed on the support 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 support body 22 from the manifold side, and the coating liquid discharge port side of the spacer forms an R shape so that the arc of the spacer becomes a concave portion in a direction in which the coating liquid discharge port 16A is narrowed. 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 initial 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 step in which the taper angle is gradually changed in a direction in which the flow path width is narrowed, and the R shape is formed as a whole. Further, the "tapered angle" is an extension of the tapered portion of the spacer and a coating formed by a pair of spacers. The angle formed by the discharge of the cloth liquid. Further, from the viewpoint of easiness of processing, it is preferably an ellipse, and it is preferably a perfect circle.

By forming the coating liquid discharge port side of the spacer 24 into an R shape, even if the flow velocity in the vicinity of the spacer 24 is lowered due to the influence of the viscous shear in the interface between the spacer 24 and the coating liquid, it is possible to face the first The end portion of the coating width A in the drawing accelerates the flow rate of the coating liquid from the interval B between the pair of spacers 24 which is wider than the coating width A. Therefore, the influence of the 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 portion, and the thick coating width of the coating film can be reduced.

Further, in the first to third embodiments, the extrusion coating device having the lip surface on the upstream side and the downstream side in the traveling direction of the support is described, but it is also possible to use the lip surface instead of the upstream side or the downstream side. An extrusion coating device having a lip surface is provided on the side.

The support used in the present embodiment is not particularly limited, and 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. The film thickness tends to be thick, and by carrying out the production method of the present embodiment, it is possible to reduce the width of the thick portion of the coating film at the end portion. 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 the following method. 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 present embodiment will be described. Figure 4 is a diagram showing the spacer of the previous tapered shape. Fig. 5 is a view showing a spacer of an R shape according to the first embodiment. Since the flow rate of the coating liquid is affected by the viscous shear in 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 the viscous shear. As shown in Fig. 4, in the previously tapered member spacer 324, the coating liquid is concentrated in a wide area in the end portion of the coating film with respect to the width direction due to the length of the tapered portion. At the end of the coating film, the thick portion of the film becomes wider. Therefore, since the area of the thick coating becomes wider, the 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 expanded into an R shape. That is, since the flow path width is narrowed immediately before coating, only the end flow rate of the coating film can be accelerated, and the coating film can be thickened only at the end portion. Therefore, it is possible to reduce the thickness of the film end portion, and it is possible to improve the productivity.

Fig. 6 is a view showing the film thickness of the end portion of the coating film produced by using the separator of the prior art and the spacer of the first embodiment. As shown in Fig. 6, it was confirmed that the coating film formed by the front end R-shaped spacer of the first embodiment was used from the end of the coating film as compared with the coating film formed using the conventional linear tapered separator. The area of the thick coated portion of the film thickness is reduced.

In addition, the "thick-coated portion region (thick coating width)" is an average value of the coating film thickness in the range of ±0.5% in the application center width including the center portion of the film, and the film thickness is +2% or more. The area that the department has.

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 applied to the inner side in the width direction of the coating film, and the coating liquid can be applied only to the vicinity of the end portion of the coated film to be produced, and the thick coating can be reduced. Part of the area.

[Second Embodiment]

Fig. 7 is a view showing the shape of the spacer 124 of the second embodiment. The spacer 124 shown in Fig. 7 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 tangent of the R shape of the spacer and the coating liquid discharge port can be reduced, and the coating liquid can be caused to flow to the end portion of the coating film. Therefore, it is possible to cause the coating liquid to flow to the end side of the produced film at a steep flow rate, and to narrow the area of the thick portion of the end portion of the produced film.

Further, it is preferable that the radius of curvature of the portion of each R shape is 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. 8 is a view showing the shape of the spacer 224 of 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 gradually changed in the direction in which the flow path width is narrowed toward the coating liquid discharge port. By making the cone angle stage 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 embodiment and the second embodiment 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 support, the coating head, the coating conditions, and the coating liquid used in the examples are as follows.

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

The coating head used was 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 support conveyance direction.

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 heat-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 support body that is continuously supported by being wound around the backup roll, using an extrusion type coating head, has a coating width of 700 mm, The coating liquid was applied so as to have 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 produced film 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 used in the examples and comparative examples are shown in Fig. 9 and Table 1. In the linear-shaped tapered 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. 9(a). The angle (α) formed by the coating 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. 9(b)).

[Evaluation method]

The film thickness of the produced coating film was measured by an optical interference layer thickness meter, and the width (the flange width (edge width)) of the fixing portion (a certain film thickness portion) from the coated end portion was measured. Thick coating width) was evaluated. The thick coating width was evaluated by the following criteria.

<flange width>

A···The thick coating area from the end is less than 2% of the coating width

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

C···The thick coating area from the end is 5% or more of the coating width

In addition, as described above, the thick coating region has a film thickness of +2% or more from the end portion with respect to the average value of the film thickness of the coating film having a coating width of ±0.5% around the center portion. The results are shown in Table 1.

As shown in Table 1, the thickness of the thick coating 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 at a width direction end portion thereof; And a coating step by extrusion coating: using a coating device and disposing a coating liquid discharge port toward the support body, and applying the coating liquid 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 narrowed. 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 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 narrowed.