WO2015025563A1

WO2015025563A1 - Die coater, coating device, coating method, and method for manufacturing electromagnetic wave-shielding film

Info

Publication number: WO2015025563A1
Application number: PCT/JP2014/062629
Authority: WO
Inventors: 川邉　茂寿; 篤志齋藤
Original assignee: コニカミノルタ株式会社
Priority date: 2013-08-20
Filing date: 2014-05-12
Publication date: 2015-02-26
Also published as: JPWO2015025563A1

Abstract

[Problem] To provide a die coater, a coating device, a coating method, and a method for manufacturing an electromagnetic wave-shielding film capable of adequately coating wide, simultaneous heavy layers even when the number of layers is increased. [Solution] A sliding-type die coater having a plurality of layered bars (40) for simultaneous heavy-layer coating. The bars (40) have a distal end part (56) in which a slit (gap) (58) is formed between another adjacent bar (40), a proximal end part (50) in contact with another bar (40), and a pocket part (53) having a concavity (54), which is a coating liquid reservoir part, the pocket part (53) being positioned between the distal end part (56) and the proximal end part (50). The coating liquid discharged from the slit (gap) (58) flows down the end face (57) of the distal end part (56). The Young's modulus of the material constituting at least the pocket part (53) is 240 GPa or higher.

Description

Die coater, coating apparatus, coating method, and electromagnetic wave shielding film manufacturing method

The present invention relates to a die coater, a coating apparatus, a coating method, and a method for manufacturing an electromagnetic wave shielding film.

In recent years, interest in energy-saving measures has increased, and it has been applied to building and vehicle window glass to reflect near-infrared light in order to reduce the load on cooling equipment by blocking the transmission of heat rays contained in sunlight. Development of electromagnetic shielding films having functions has been actively conducted.

The electromagnetic wave shielding film is formed by alternately laminating high refractive index layers and low refractive index layers. Generally, the larger the number of layers, the higher the electromagnetic wave reflectivity and the higher the shielding effect. However, the layers are sequentially formed by coating, and there is a problem in productivity (see, for example, Patent Documents 1 and 2). Therefore, in order to improve productivity, application of a slide type die coater capable of performing multilayer coating (simultaneous multilayer coating) at once has been proposed.

JP-A-8-110401 JP 2004-123766 A

However, the number of bars that constitute the slide type die coater corresponds to the number of layers of the electromagnetic shielding film to be manufactured. Therefore, when the number of coating layers is increased in order to increase the number of layers of the electromagnetic shielding film to be manufactured, the number of bars installed increases, so that the slide surface constituted by the end surfaces of the bars through which the coating liquid flows down becomes long. As a result, the flow of the coating liquid is likely to be disturbed, so that uniform coating becomes difficult, and the coating liquid is mixed to adversely affect the electromagnetic shielding film, for example, non-uniformity (fluctuation) in film thickness or There is a possibility that performance such as reflectivity is deteriorated.

In order to prevent disturbance of the flow of the coating liquid, it is effective to shorten the slide surface, but in order to do so, it is necessary to make the bar thinner. However, when the bar is thinned, the effect of the difference between the low refractive index layer coating liquid viscosity and the high refractive index layer coating liquid viscosity, that is, the gap that is the flow path of the coating liquid formed between the bars is applied to the low refractive index layer coating. There is a problem of being affected by the pressure difference between the internal pressure based on the pressure loss generated when the liquid passes and the internal pressure based on the pressure loss generated when the high refractive index layer coating liquid passes.

For example, the bar is pressurized from the higher pressure (the side through which the low refractive index layer coating solution having a large viscosity passes) to the lower side (the side through which the high refractive index layer coating solution having a low viscosity passes), thereby , The deformation of the bar, the uniformity of the gap in the coating width direction is deteriorated, the coating film thickness becomes non-uniform, and as a result, the uniformity of the optical properties of the electromagnetic wave shielding film to be produced decreases, for example, the color There is a problem that unevenness occurs.

Also, a wide bar may bend or warp, which deteriorates the uniformity of the gap in the coating width direction and makes the coating thickness in the coating width direction non-uniform. It has the problem that it is difficult to implement well.

The present invention has been made in order to solve the problems associated with the prior art described above, and is capable of satisfactorily performing wide simultaneous multilayer coating even when the number of layers is increased, a coating apparatus, and a coating method. And it aims at providing the manufacturing method of an electromagnetic wave shielding film.

The above object of the present invention is achieved by the following means.

(1) having a plurality of stacked bars for simultaneous multi-layer application;
The bar
A tip that forms a gap between another adjacent bar;
A proximal end abutting against the another bar;
A pocket portion located between the distal end portion and the base end portion and having a recess that is a coating liquid reservoir,
A slide type die coater in which the coating liquid discharged from the gap flows down the end face of the tip,
The die coater whose Young's modulus of the material which comprises the said pocket part at least is 240 GPa or more.

(2) The die coater according to (1) above, wherein the material has a Young's modulus of 280 GPa or more.

(3) The die coater according to (1) or (2) above, wherein the material is cemented carbide or ceramics.

(4) The die coater according to any one of (1) to (3), wherein at least the pocket portion is made of a single material.

(5) The die coater according to any one of (1) to (4), wherein the pocket portion has a thickness of 15 mm or less.

(6) The die coater according to (5), wherein the pocket portion has a thickness of 10 mm or less.

(7) The die coater according to (5) or (6) above, wherein the pocket portion has a thickness of 5 mm or more.

(8) The die coater according to any one of (1) to (7), wherein the length and height of the bar are 1 m or more and 80 mm or more, respectively.

(9) The die coater according to any one of (1) to (8) above,
A first container for holding a first coating liquid;
A second container for holding a second coating liquid;
A first coating liquid supply system for supplying the first coating liquid held in the first container to the die coater;
A second coating solution supply system for supplying the second coating solution held in the second container to the die coater;
A coating apparatus.

(10) The pressure difference between the internal pressure of the concave portion of the pocket portion of the bar supplied with the second coating liquid and the internal pressure of the concave portion of the pocket portion of the bar supplied with the first coating liquid is 0.3 MPa or less. The coating apparatus according to (9), which is set to be

(11) The coating apparatus according to (10), wherein the pressure difference is set to be 0.1 MPa or less.

(12) The coating layer of the first coating liquid constitutes the high refractive index layer in the electromagnetic wave shielding film having a high refractive index layer and a low refractive index layer laminated alternately,
The coating apparatus according to any one of (9) to (11), wherein the coating layer of the second coating liquid constitutes the low refractive index layer.

(13) The first coating liquid and the second coating liquid are supplied to the die coater according to any one of (1) to (8) above, and discharged from the gap at the tip of the bar of the die coater. Then, the coating method of applying the first and second coating liquid coating layers and the second coating liquid coating layer alternately to each other, and simultaneously coating the film substrate by causing the end surface of the tip portion to flow down.

(14) The pressure difference between the internal pressure of the concave portion of the pocket portion of the bar supplied with the second coating liquid and the internal pressure of the concave portion of the pocket portion of the bar supplied with the first coating liquid is 0.3 MPa or less. The coating method according to (13) above.

(15) The coating method according to (14), wherein the pressure difference is 0.1 MPa or less.

(16) The coating layer of the first coating liquid constitutes the high refractive index layer in the electromagnetic wave shielding film having a high refractive index layer and a low refractive index layer laminated alternately,
The coating method according to any one of (13) to (15), wherein the coating layer of the second coating liquid constitutes the low-index layer.

(17) A method for producing an electromagnetic wave shielding film comprising a step of simultaneously applying a high refractive index layer and a low refractive index layer by using the coating method described in (16) above.

According to the die coater, the coating device, the coating method, and the electromagnetic wave shielding film manufacturing method according to the present invention, the Young's modulus of the material constituting at least the pocket portion is 240 GPa or more. That is, the pocket portion, which is the main portion of the bar that is easily deformed under the influence of pressure, is made of a material having a high Young's modulus that is difficult to twist. This suppresses the deformation of the bar, thereby maintaining the uniformity of the gap in the coating width direction and preventing the coating film thickness in the coating width direction from becoming nonuniform. The uniformity of the optical characteristics is good. Further, since deformation due to the effect of the pressure difference and occurrence of bending and warping due to the widening of the bar are suppressed, the bar can be made wide and thin. Furthermore, by reducing the thickness of the bar, even if the number of installed bars (number of layers) increases, the sliding surface constituted by the end surface of the bar through which the coating liquid flows down is prevented from becoming long. This prevents the turbulence in the flow. Therefore, it is possible to provide a die coater, a coating apparatus, a coating method, and a method for manufacturing an electromagnetic wave shielding film, which are capable of satisfactorily performing wide simultaneous multilayer coating even when the number of layers is increased.

Further objects, features, and characteristics of the present invention will become apparent by referring to the preferred embodiments illustrated in the following description and the accompanying drawings.

It is the schematic for demonstrating the coating device which has the die-coater which concerns on embodiment of this invention. It is a top view for demonstrating the side wall part of the die-coater shown by FIG. It is a top view for demonstrating the bar | burr of the die-coater shown by FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. It is sectional drawing for demonstrating another aspect of the bar | burr of a die-coater. It is sectional drawing for demonstrating another aspect of the bar | burr of a die-coater. It is a flowchart for demonstrating the manufacturing method of the electromagnetic wave shielding film which concerns on embodiment of this invention. It is sectional drawing for demonstrating the application | coating process which concerns on embodiment of this invention. It is sectional drawing for demonstrating the application | coating conditions in an application | coating process. It is sectional drawing for demonstrating a comparative example. It is a table which shows the test result for demonstrating the influence of the Young's modulus and the pressure difference with respect to the film thickness fluctuation rate of an electromagnetic wave shielding film. It is a table which shows the test result for demonstrating the influence of the Young's modulus with respect to the film thickness fluctuation rate of an electromagnetic wave shielding film, and the thickness of the pocket part of a bar.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

1 is a schematic view for explaining a coating apparatus having a die coater according to an embodiment of the present invention, FIG. 2 is a plan view for explaining a side wall portion of the die coater shown in FIG. 3 is a plan view for explaining the bar of the die coater shown in FIG. 1, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

The coating apparatus 10 according to the present embodiment is used to manufacture an electromagnetic wave shielding film formed by alternately laminating a plurality of high refractive index layers and low refractive index layers by simultaneous multilayer coating, and is shown in FIG. As described above, a transport system 20, a die coater 30, a coating liquid supply system 70, and

pressure sensors

81 and 82 are included.

The electromagnetic wave shielding film according to the present embodiment has an optical property having high optical characteristics in the visible light region (wavelength 380 to 780 nm) and high reflectance in the near infrared light region (780 to 2500 nm) ( Near-infrared light reflecting film), which is disposed in a building outdoor window, automobile window, agricultural greenhouse, etc., and used to impart a heat ray reflecting effect.

"High refractive index layer" and "low refractive index layer", when comparing the refractive index difference between two adjacent layers, the higher refractive index layer is the high refractive index layer, the lower one is the low refractive index layer Means. The reflectance in the specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of layers. The larger the difference in refractive index, the higher the reflectance with a smaller number of layers.

The conveyance system 20 includes a film base material 22 and a back roll 24. The film substrate 22 is a belt-like support on which the coating liquid L is applied. The back roll 24 is arranged inside the film base 22 and is configured to transport the film base 22 from the upstream side to the downstream side in the application direction (transport direction) F by being driven to rotate. ing.

The die coater 30 is a slide type, and is configured to be able to apply the application layers corresponding to each layer of the electromagnetic wave shielding film in a lump (simultaneous multi-layer application), and the rectangular bars 40 are sequentially stacked. It has the laminated body 32 comprised and the side wall part 60. FIG.

The bar 40 includes a front bar 42, a plurality of intermediate bars 44, and a back bar 46, which have substantially the same shape. The front bar 42 is a bar that occupies the lowermost layer of the laminate 32 and is positioned in the vicinity of the film substrate 22. The back bar 46 is a bar that occupies the uppermost layer of the stacked body 32. The intermediate bar 44 is a bar that occupies an intermediate layer located between the front bar 42 and the back bar 46. As shown in FIG. 2, the side wall portions 60 are disposed on both end surfaces of the laminate 32 in the application width direction W. The application width direction W is orthogonal to the application direction (conveyance direction) F.

As shown in FIGS. 3 and 4, the bar 40 has a proximal end portion 50, a pocket portion 53, and a distal end portion 56 in order from the proximal end side.

The base end portion 50 has a through hole 52 communicating with the coating liquid supply system 70. The through hole 52 is located in the center of the application width direction W of the base end portion 50 and extends from the end surface of the base end portion 50 toward the pocket portion 53.

A thickness D ₁ of the proximal end portion 50 is set to be larger than a thickness D ₂ of the distal end portion 56. Therefore, when the bars 40 are stacked, the base end portion 50 comes into contact with the base end portion 50 of another adjacent bar, while the front end portion 56 and the front end portion 56 of another adjacent bar are in between. A slit (gap) 58 having a thickness D ₃ (= D ₁ −D ₂ ) is formed. In the following, the thickness _{D 3} are referenced by the slit spacing _{D 3.} Reference numeral 51 denotes an end face of the base end portion 50.

The slit 58 functions as a passage through which the coating liquid passes. Since the coating liquid discharged from the front end of the slit 58 flows down the end surface 57 of the front end portion 56, the end surface 57 functions as a slide surface on which the coating liquid flows down.

The pocket portion 53 has a concave portion 54 formed to extend in the coating width direction W of the bar 40. The recess 54 is a coating liquid reservoir that communicates with the slit 58 and the through hole 52. The concave portion 54 is used to stably spread the coating liquid from the through hole 52 (coating liquid supply system 70) in the coating width direction W and stably supply the slit 58.

Depending on the stacking position of the bar 40, the through hole 52 of the bar 40, the high-refractive index layer coating solution L ₁ which is a first coating liquid constitutes the high refractive index layer and the low refractive index layer and thus the second coating liquid and the low-refractive index layer coating solution L _2, but are alternately introduced. For example, the low refractive index layer coating liquid L ₂ is introduced into the through hole 52 of the front bar 42, and the high refractive index layer coating liquid L ₁ is introduced into the through hole of the intermediate bar 44 adjacent to the front bar 42. , the through hole 52 of another intermediate bar 44 adjacent to the intermediate bar 44, the low refractive index layer coating solution L ₂ is introduced.

Therefore, the number of slits 58 is equal to the number of layers of the electromagnetic shielding film, and the number of stacked intermediate bars 44 is adjusted according to the number of layers of the electromagnetic shielding film. The length of the slide surface is the sum of the lengths of the intermediate bar 44 where the coating liquid stacked in two or more layers flows down and the end surface 57 of the front end portion 56 of the front bar 42. The remaining thickness of the intermediate bar 44 and the thickness of the front bar 42 are approximately equal to the total value.

Coating liquid supply system 70, as shown in FIG. 1, is used to provide a low refractive index layer coating solution L ₂ and the high-refractive index layer coating solution L ₁ die coater 30, the

preparation kettle

72 and 76, It has

piping systems

73 and 77 and pumps 74 and 78.

Preparation kettle 72, a low refractive index layer coating solution L ₂ is prepared, a predetermined temperature (e.g., 30 ° C. or higher) is a vessel used to hold in. The piping system 73 connects the preparation kettle 72 and the through hole 52 of the base end portion 50 of the bar 40 for the low refractive index layer coating solution. The pump 74 is used for pumping the prepared low refractive index layer coating liquid L ₂ through the piping system 73.

Preparation kettle 76, the high refractive index layer coating solution L ₁ was prepared, a predetermined temperature (e.g., 30 ° C. or higher) is a vessel used to hold in. The piping system 77 connects the preparation pot 76 and the through hole 52 of the base end portion 50 of the bar 40 for the high refractive index layer coating solution. Pump 78, via the piping system 77 is used has been prepared with high refractive index layer coating solution L ₁ for pumping. The

pumps

74 and 78 are, for example, gear pumps or tube pumps.

The

pressure sensors

81 and 82 are disposed in the

piping systems

73 and 77 in the vicinity of the die coater 30 and are used for detecting the pressure difference ΔP. The pressure difference ΔP is, the internal pressure of the recess 54 of the pocket portion 53 of the bar 40 having a low refractive index layer coating solution L ₂ is supplied, the recess of the pocket portion 53 of the bar 40 to the high refractive index layer coating solution L ₁ is supplied It is a difference between the internal pressure of 54 and 0.3 MPa or less, more preferably 0.1 MPa or less, as will be described later.

The

pressure sensors

81 and 82 can be disposed on the inner surface of the concave portion 54 of the pocket portion 53 or on the inner surface of the side wall portion 60 in contact with the concave portion 54 of the pocket portion 53, for example. The pressure difference ΔP can also be directly detected by a differential pressure gauge.

Next, the constituent materials of the bar 40 of the die coater 30 will be described.

The bar 40 is made of a material having a high Young's modulus E that is difficult to be twisted. The Young's modulus E of the material is 240 GPa or more, preferably 280 GPa or more, more preferably 390 GPa or more, as will be described later. Examples of the material having a large Young's modulus E that hardly causes twisting are ceramics (alumina) and cemented carbide. Conventionally, articles composed of ceramics (alumina) or cemented carbide have been mainly short articles having a length of 500 mm or less, or thin articles having a long diameter of about 50 mm at the longest. However, due to recent progress in manufacturing technology, it is possible to manufacture products having a length of 1 m or more and a cross-sectional major axis of about 80 mm or more.

The bar 40 is made of a material having a large Young's modulus E as described above. As a result, the deformation of the bar 40 is suppressed, the uniformity of the slit (gap) 58 in the coating width direction W is maintained, and the coating film thickness in the coating width direction W is prevented from becoming non-uniform. The uniformity of the optical properties of the electromagnetic wave shielding film is good. In addition, since deformation due to the influence of the pressure difference ΔP and occurrence of bending and warping due to the widening of the bar are suppressed, the bar 40 can be made wide and thin. Further, by making the bar 40 thin, even if the number of installed bars (number of layers) is increased, the slide surface (end surface 57) is suppressed from becoming long, and the flow of the coating liquid is prevented from being disturbed. Can be removed. Therefore, even when the number of layers is increased, it is possible to satisfactorily perform wide simultaneous multilayer coating.

When the bar 40 is manufactured using ceramics, unlike a metal material, internal stress does not accumulate in the manufacturing process, and therefore, distortion deformation due to internal stress does not occur during finish grinding and after finishing. Therefore, it is possible to finish the bar 40 with high accuracy, and it is easy to ensure accuracy such as straightness and flatness of the bar 40. In particular, when the bar 40 is thin, distortion deformation is likely to occur with a metal material, and therefore, the accuracy of the bar 40 can be improved by using ceramics.

It should be noted that the bar 40 is not limited to a form in which the entire bar 40 is made of a material having a high Young's modulus E that is less likely to be twisted. For example, the pocket portion 53, which is the main portion of the bar 40, is easily deformed due to the influence of pressure. Therefore, if necessary, only the material constituting the pocket portion 53 is less likely to be twisted and has a large Young's modulus E. It can also be composed of materials.

5 and 6 are cross-sectional views for explaining another embodiment of the bar of the die coater.

The pocket portion 53 is not limited to a form composed of a single material, and a composite material integrated using a fastening member such as a bolt or an adhesive can also be applied. For example, as shown in FIG. 5, it is possible to have a two-layer structure made of different materials, or as shown in FIG. 6, only the periphery of the concave portion 54 of the pocket portion 53 can be made of another material. .

Next, a method for manufacturing an electromagnetic wave shielding film according to an embodiment of the present invention will be described.

FIG. 7 is a flowchart for explaining a method of manufacturing an electromagnetic wave shielding film according to an embodiment of the present invention.

The manufacturing method of the electromagnetic wave shielding film according to the embodiment of the present invention includes a preparation process, a coating process, and a drying process, as shown in FIG.

In the preparation step, for example, metal oxide particles, resin binder, curing agent, additive, solvent and the like are mixed to prepare a high refractive index layer coating solution and a low refractive index layer coating solution, respectively.

In the coating step, the high refractive index layer coating liquid and the low refractive index layer coating liquid corresponding to each layer of the electromagnetic wave shielding film are collectively coated (simultaneous multilayer coating) on the film substrate.

As the film substrate, various resin films such as polyolefin film, polyester film, polyvinyl chloride film, and cellulose acetate film can be applied. Polyolefin is, for example, polyethylene or polypropylene. Examples of the polyester include polyethylene terephthalate and polyethylene naphthalate.

In the drying step, the electromagnetic wave shielding film is produced by drying and thermally curing the film substrate on which the high refractive index layer coating solution and the low refractive index layer coating solution are applied in multiple layers. The drying conditions are appropriately set in consideration of the evaporation temperature of the volatile components contained in the high refractive index layer coating solution and the low refractive index layer coating solution, the curing temperature of the curing agent, the heat resistant temperature of the film substrate, and the like. . The dried electromagnetic shielding film is then cut into an appropriate size as necessary.

As will be described later, in the coating process, even when the number of layers is increased, a wide simultaneous multilayer coating can be performed satisfactorily, and since the coating thickness per layer is reduced, the drying load in the drying process is reduced. Is done.

Next, the constituent materials of the coating liquid will be specifically described.

The metal oxide particles of the high refractive index layer coating liquid are, for example, titanium dioxide, zirconium oxide, zinc oxide, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide, ferric oxide, They are iron black, copper oxide, magnesium oxide, magnesium hydroxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon and tin oxide. In order to obtain a transparent and high refractive index, it is preferable to contain fine titanium oxide particles and fine zirconia oxide particles. The concentration of the metal oxide particles is, for example, 1 to 50% by mass.

The metal oxide particles of the low refractive index layer coating solution are, for example, silicon dioxide and colloidal silica. The concentration of the metal oxide particles is, for example, 1 to 50% by mass.

Resin binders are, for example, polyvinyl alcohol, gelatin, water-soluble cellulose derivatives, thickening polysaccharides, and polymers having reactive functional groups. The concentration of the resin binder in the high refractive index layer coating solution is, for example, 0.5 to 10% by mass. The concentration of the resin binder in the low refractive index layer coating solution is 1 to 10% by mass.

The curing agent is not particularly limited as long as it causes a curing reaction with the resin binder. When polyvinyl alcohol is selected as the resin binder, for example, boric acid and salts thereof.

Additives are, for example, ultraviolet absorbers, fading inhibitors, surfactants, fluorescent brighteners, pH adjusters, antifoaming agents, lubricants, preservatives, and antistatic agents.

The solvent is, for example, water, an organic solvent, or a mixed solution thereof. The organic solvent is methanol, ethanol, ethyl acetate or the like.

Next, the preparation process and the coating process will be described in detail.

8 is a cross-sectional view for explaining a coating process according to an embodiment of the present invention, FIG. 9 is a cross-sectional view for explaining a coating condition in the coating process, and FIG. 10 is for explaining a comparative example. It is sectional drawing.

In the preparation process, the metal oxide particles for low refractive index layer, the resin binder, a curing agent, additives, solvents and the like, after turning the preparation kettle 72, is mixed, the low refractive index layer coating solution L ₂ is prepared whereas, the metal oxide particles for high refractive index layer, the resin binder, a curing agent, additives, solvents and the like, after turning the preparation kettle 76, is mixed, the high refractive index layer coating solution L ₁ is prepared. Then, the low refractive index layer coating solution L ₂ and the high-refractive index layer coating solution L ₁ which is prepared is held at a predetermined temperature (e.g., 30 ° C. or higher).

In the coating step, the prepared low refractive index layer coating liquid L ₂ and high refractive index layer coating liquid L ₁ are pumped by

pumps

74 and 78, and are connected to the low refractive index layer coating liquid via the

piping systems

73 and 77. To the through hole 52 of the base end portion 50 of the bar 40 for use and the through hole 52 of the base end portion 50 of the bar 40 for the high refractive index layer coating solution.

Thus, as shown in FIG. 8, in accordance with the stacking position of the bar 40, introduced into the through hole 52 of the bar 40, in the high refractive index layer coating solution L ₁ and the low refractive index layer coating solution L ₂ is alternately Is done. For example, the low refractive index layer coating liquid L ₂ is introduced into the through hole 52 of the front bar 42, and the high refractive index layer coating liquid L ₁ is introduced into the through hole of the intermediate bar 44 adjacent to the front bar 42. , the through hole 52 of another intermediate bar 44 adjacent to the intermediate bar 44, the low refractive index layer coating solution L ₂ is introduced.

The coating solution is spread evenly in the coating width direction W in the concave portion 54 of the pocket portion 53 and introduced into the slit 58. As shown in FIG. 8, the coating liquid that has passed through the slit 58 flows down the end surface 57 of the front end portion 56 of the bar 40 and flows down the end surface 57 of the front end portion 56 of another bar 40 positioned below. And overlap one after another. And the coating liquid which flows down is comprised from the layer corresponding to the number of layers of an electromagnetic wave shielding film, when it overlaps with the coating liquid which passed the slit 58 of the front bar 42. FIG.

Then, the coating liquid L is separated from the front bar 42 which is the lowermost bar 40 and flows down to the film base material 22 to be applied.

Further, when the coating liquid L passes through the slit 58 of the bar 40, a pressure loss (slit resistance) is generated, and thereby pressure (internal pressure) is generated inside the die coater 30. The internal pressure is affected by the viscosity of the coating liquid L.

The viscosity μ ₁ of the high refractive index layer coating liquid L ₁ is 3 mPa · s or more and 30 mPa · s or less. The viscosity μ ₂ of the low refractive index layer coating liquid L ₂ is 50 mPa · s or more and 500 mPa · s or less, which is one digit or more larger than the viscosity μ _{1 of} the high refractive index layer coating liquid L ₁ . Therefore, the internal pressure P _{1 of the} concave portion 54 to which the high refractive index layer coating liquid L ₁ is supplied is smaller than the internal pressure P _{2 of the} concave portion 54 to which the low refractive index layer coating liquid L ₂ is supplied, and is adjacent (adjacent). An internal pressure difference ΔP occurs between the bars 40.

Thus, as shown in the comparative example of FIG. 10, towards the low pressure (high refractive index layer coating solution L ₁ is fed toward the high pressure (recess 54 having a low refractive index layer coating solution L ₂ is supplied) The bar 40 positioned between the recess 54) is pushed and deformed from the high pressure to the low pressure. As a result, the slit gap D ₃₂ of the slit 58 having a low refractive index layer coating solution L ₂ passes is enlarged, the slit gap D ₃₁ of the slit 58 the high refractive index layer coating solution L ₁ passes is reduced. That is, the distribution of the slit gap in the coating width direction is deteriorated, so that the uniformity in the coating width direction of the coating liquid L flowing out from the slit 58 is lowered, and finally a uniform coating film thickness cannot be obtained.

On the other hand, the internal pressure P2 of the recess 54 of the pocket portion 53 of the bar 40 having a low refractive index layer coating solution L ₂ is supplied, the high-refractive index layer coating solution L ₁ is a concave portion 54 of the pocket portion 53 of the bar 40 to be supplied The deformation of the bar caused by the pressure difference ΔP between the internal pressure P1 and the internal pressure P1 is considered to be the deflection of the bar 40 due to the load generated by the pressure difference ΔP. Therefore, the deformation amount of the bar 40 is inversely proportional to the Young's modulus E of the material constituting the bar 40.

In the coating process according to the present embodiment, as described above, the bar 40 made of a material having a high Young's modulus E that is less likely to be twisted is applied. As a result, the deformation of the bar 40 is suppressed, the uniformity of the slit (gap) 58 in the coating width direction W is maintained, and the coating film thickness in the coating width direction W is prevented from becoming non-uniform. The uniformity of the optical properties of the electromagnetic wave shielding film is good. In addition, since deformation due to the influence of the pressure difference ΔP and occurrence of bending and warping due to the widening of the bar are suppressed, the bar 40 can be made wide and thin. Furthermore, even if the number of installed bars (number of layers) is increased, the slide surface (end surface 57) is suppressed from becoming long, and the flow of the coating liquid is prevented from being disturbed. Therefore, even when the number of layers is increased, it is possible to satisfactorily perform wide simultaneous multilayer coating.

The high-refractive index layer coating solution L ₁ and the low refractive index layer coating solution L ₂ is coated film substrate 22 is cooled once to 1 ~ 15 ° C., it is introduced into the drying step. Thus, the high-refractive index layer coating solution L ₁ and the low refractive index layer coating solution L ₂ is dried by heat curing. The drying temperature is 10 ° C. or higher, for example, a wet bulb temperature of 5 to 50 ° C. and a coating surface temperature of 10 to 50 ° C. Incidentally, to once cool the film substrate, by increasing the viscosity of the high refractive index layer coating solution L ₁ and the low refractive index layer coating solution L _2, to suppress the mixing of the coating layers, The film substrate This is to improve the handleability of the 22.

Next, the conditions under which a wide simultaneous multilayer coating can be satisfactorily performed even when the number of layers is increased will be described in detail.

FIG. 11 is a table showing test results for explaining the influence of the Young's modulus and pressure difference on the film thickness fluctuation rate of the electromagnetic wave shielding film, and FIG. 12 shows the Young's modulus and bar with respect to the film thickness fluctuation rate of the electromagnetic wave shielding film. It is a table which shows the test result for demonstrating the influence of the thickness of a pocket part.

First, common conditions relating to the test, that is, conditions for preparing a low refractive index layer coating solution, conditions for preparing a high refractive index layer coating solution, and coating conditions will be described.

The coating solution for the low refractive index layer is composed of 12 parts by mass of colloidal silica (Snowtex OXS, manufactured by Nissan Chemical Industries, Ltd., solid content 10% by mass), polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, 2 parts by weight of a 5% by weight aqueous solution of Kuraray Co., Ltd., and 10 parts by weight of a 3% by weight aqueous boric acid solution were added, and the mixture was heated to 45 ° C. and stirred while polyvinyl alcohol (PVA-117, polymerization degree 1700, saponification). 20 mass parts of 5 mass% aqueous solution of degree 98.5 mol%, manufactured by Kuraray Co., Ltd., 1 mass part of 1 mass% aqueous solution of surfactant (Rapisol A30, manufactured by NOF Corporation) were added, and 55 mass parts of pure water was added. And prepared by stirring and mixing.

The coating solution for the high refractive index layer is 5 parts of polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, manufactured by Kuraray Co., Ltd.) in 30 parts by mass of silica-attached titanium dioxide sol (solid content 20.0% by mass). After adding 2 parts by weight of 2% by weight aqueous solution, 10 parts by weight of 3% by weight aqueous boric acid solution, and 10 parts by weight of 2% by weight aqueous citric acid solution, the mixture was heated to 45 ° C. and stirred while polyvinyl alcohol (PVA-617, polymerized). 20 parts by weight of a 5% by weight aqueous solution having a degree of 1700, a degree of saponification of 95.0 mol%, manufactured by Kuraray Co., Ltd., and 1 part by weight of a 1% by weight aqueous solution of a surfactant (Rapidol A30, manufactured by NOF Corporation) It was prepared by adding part by mass and stirring and mixing.

The silica-attached titanium dioxide sol is obtained by adding 2 parts by mass of pure water to 0.5 parts by mass of 15.0% by mass titanium oxide sol (SRD-W, volume average particle size 5 nm, rutile titanium dioxide particles, manufactured by Sakai Chemical Co., Ltd.). Then, heated to 90 ° C., 1.3 parts by mass of an aqueous silicic acid solution (sodium silicate 4 (manufactured by Nippon Chemical Co., Ltd.) diluted with pure water so that the SiO ₂ concentration becomes 2.0% by mass) It was obtained by gradually adding and heat-treating at 175 ° C. for 18 hours in an autoclave, then cooling and concentrating with an ultrafiltration membrane.

The low refractive index layer coating solution and the high refractive index layer coating solution were kept at 45 ° C. and supplied to a die coater, and 15 layers were simultaneously coated. The lowermost layer and the uppermost layer are low refractive index layers, and the low refractive index layer is included one more than the high refractive index layer.

The slit gap was set to 0.2 mm. The viscosity of the high refractive index layer coating solution and the low refractive index layer coating solution was set to 10 mPa · s and 100 mPa · s.

The film substrate was a polyethylene terephthalate film (A4300 manufactured by Toyobo Co., Ltd .: double-sided easy-adhesion layer) having a thickness of 50 μm and a width of 2000 mm, and the temperature was raised to 45 ° C. during application of the coating solution. The front bar and back bar of the die coater were 40 mm thick. The coating speed and coating width were set to 50 m / min and 1950 mm. The coating thickness of the low refractive index layer and the high refractive index layer was set to be 150 nm as an average film thickness during drying.

Next, a method of calculating the film thickness fluctuation rate of the electromagnetic wave shielding film will be described.

The film thickness fluctuation rate V [%] of the electromagnetic wave shielding film is a value obtained by dividing the film thickness fluctuation width by the film thickness average value and multiplying by 100. The film thickness variation width is a difference between the minimum value and the maximum value of the film thickness. The film thickness average value is an average value related to the entire width of the film thickness measured at intervals of 50 mm in the coating width direction.

The film thickness was obtained by measuring each layer after digitizing an image obtained by observing the cross section of the electromagnetic wave shielding film produced under the above conditions and performing image processing for adjusting contrast. The cross section was observed using an electron microscope (FE-SEM, S-5000H type, manufactured by Hitachi, Ltd.) with the number of fields of view selected so that a length of 1 cm could be observed under the condition of an acceleration voltage of 2.0 kV. The film thickness is an average value of 1000 measurement results.

Next, the influence of Young's modulus and pressure difference on the film thickness fluctuation rate of the electromagnetic shielding film will be described.

As an individual condition related to the test, by changing the constituent material of the bar, the Young's modulus E is changed in the range of 106 to 540 GPa, and the viscosity is adjusted by adding pure water to the coating solution. The pressure difference ΔP was changed in the range of 0.1 to 1.0 MPa. The pressure difference ΔP is, the internal pressure P ₂ of the recess of the pocket portion of the bar having a low refractive index layer coating solution L ₂ is supplied, the recess of the pocket portion of the bar which high refractive index layer coating solution L ₁ is supplied internal pressure P ₁ and the pressure difference. The thickness _{D 1} and a thickness _{D 4} of the pocket portion of the proximal end portion of the bars are common, it was set to 15mm and 10 mm.

As shown in FIG. 11, a bar whose constituent material is ceramic and Young's modulus E is 240 GPa or more and a bar whose constituent material is cemented carbide and whose Young's modulus E is 240 GPa or more are pure titanium and Young's modulus E Compared to a bar having a thickness of 204 GPa or less and a constituent material of SUS630 (precipitation hardening stainless steel) and a Young's modulus E of 204 GPa or less, the film thickness variation rate (V) is good and a uniform coating film is obtained. I was able to.

In particular, a bar whose constituent material is ceramics (zirconia) and Young's modulus E is 240 GPa has a film thickness variation rate (V) of 3.0% or less when the pressure difference ΔP is 0.5 MPa or less. A bar whose constituent material is ceramics (alumina 90%) and whose Young's modulus E is 280 GPa has a film thickness variation rate (V) of 1.0% or less regardless of the pressure difference ΔP. A bar whose constituent material is ceramic (alumina 99.8%) and Young's modulus E is 390 GPa or more and a bar whose constituent material is cemented carbide and whose Young's modulus E is 390 GPa or more have a film thickness variation rate (V) of 0. It was 5% or less.

That is, the bar very thin and the thickness _{D 4} is 10mm in the pocket of, and even when the pressure difference ΔP as exceeding 0.1 MPa, Young's modulus E is equal to or larger than 240 GPa, suppressing deformation of the bars It is shown that the uniformity of the slit (gap) in the coating width direction is maintained, and the Young's modulus E is preferably 280 GPa or more, more preferably 390 GPa or more. In addition, there is no restriction | limiting in particular in the upper limit of the Young's modulus E, The number of layers can be increased, so that it is large, but applicable constituent materials are limited.

Next, the influence of the Young's modulus and the thickness of the pocket of the bar on the film thickness fluctuation rate of the electromagnetic shielding film will be described.

As a separate condition according to the test, the Young's modulus E, by varying the bar of the material, was varied in the range of 106 ~ 540GPa, and a thickness _{D 4} of the pocket portion of the bar, in the range of 5 ~ 15 mm Changed. The thickness D ₁ of the proximal end portion of the bars, depending on the thickness of the pocket portion was changed in the range of 10 ~ 20 mm. The pressure difference ΔP is common and was set to 0.3 MPa.

As shown in FIG. 12, a bar whose constituent material is ceramic and Young's modulus E is 240 GPa or more and a bar whose constituent material is cemented carbide and whose Young's modulus E is 240 GPa or more are composed of pure titanium and Young's modulus E. Compared to a bar having a thickness of 204 GPa or less and a constituent material of SUS630 (precipitation hardening stainless steel) and a Young's modulus E of 204 GPa or less, the film thickness variation rate (V) is good and a uniform coating film is obtained. I was able to.

In particular, the bar construction material ceramics (zirconia) and Young's modulus E is 240GPa, when the thickness _{D 4} of the pocket portion is not less than 10 mm, the thickness variation rate (V) was 3.0% or less. Constituent materials are ceramics (90% alumina) and Young's modulus E is 280GPa bars, regardless of the thickness _{D 4} of the pocket portion, the thickness variation rate (V) was 1.0% or less. A bar whose constituent material is ceramic (alumina 99.8%) and Young's modulus E is 390 GPa or more and a bar whose constituent material is cemented carbide and whose Young's modulus E is 390 GPa or more have a film thickness variation rate (V) of 0. It was 5% or less.

That is, even less bar pocket portion thickness D ₄ is 15mm in, if the Young's modulus E is 240GPa or more, it is possible to suppress deformation of the bars, uniform slit coating width (clearance) The Young's modulus E is preferably 280 GPa or more, and more preferably 390 GPa or more, as in the test results shown in FIG.

Thus, for example, by setting the thickness D ₄ of the pocket portion 53 of the bar 40 to 15mm or less, to thin the bar 40 (thinning and weight reduction) it is possible, the installation number of the bar 40 (the number of layers ) Is suppressed, it is possible to prevent the slide surface from becoming long, so that the flow of the coating liquid is prevented from being disturbed. In addition, the die coater 30 can be reduced in size, space-saving, energy saving, and apparatus cost can be reduced, handling is easy, and workability can be improved and failure in the coating process can be expected. Note that the lower limit of the thickness D ₄ of the pocket portion of the bar restriction is not, it is possible to increase the the thinner the number of layers. However, the thickness D ₄ of the pocket portion of the bar, an excessively reduced, it becomes susceptible to the pressure difference [Delta] P, is preferably at least 5 mm.

As described above, in the present embodiment, at least the pocket portion, which is the main portion of the bar, is made of a material having a high Young's modulus that is unlikely to be twisted. As a result, the deformation of the bar is suppressed, the uniformity of the slit (gap) in the coating width direction is maintained, and the coating film thickness in the coating width direction is prevented from becoming non-uniform, so that the manufactured electromagnetic shielding film The uniformity of the optical characteristics is good. Further, since deformation due to the effect of the pressure difference and occurrence of bending and warping due to the widening of the bar are suppressed, the bar can be made wide and thin. Furthermore, by making the bar thin, even if the number of installed bars (number of layers) is increased, the slide surface is prevented from becoming long, and the flow of the coating liquid is prevented from being disturbed. Therefore, it is possible to provide a die coater, a coating apparatus, a coating method, and a method for manufacturing an electromagnetic wave shielding film, which are capable of satisfactorily performing wide simultaneous multilayer coating even when the number of layers is increased.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, the electromagnetic wave shielding film can be applied to a visible light reflecting film, a far infrared reflecting film, and an ultraviolet reflecting film. In this case, the electromagnetic wave shielding film is designed to reflect visible light, far infrared light, or ultraviolet light instead of near infrared light by adjusting the optical film thickness of the high refractive index layer and the low refractive index layer. .

It is also possible to arrange a structure in which high refractive index layers and low refractive index layers are alternately laminated on both surfaces of the film substrate. This is performed, for example, by performing simultaneous multi-layer coating on one side of the film substrate and drying, and then performing simultaneous multi-layer coating again on the other side of the film substrate and drying. The It is also possible to increase the number of installed high refractive index layers than the number of installed low refractive index layers. This is performed by disposing the high refractive index layer in the lowermost layer and the uppermost layer of the structure in which the high refractive index layer and the low refractive index layer are alternately laminated. It is also possible to make the number of the low refractive index layers and the number of the high refractive index layers the same.

It is also possible to improve the clearance accuracy between the die coater and the film substrate by arranging a decompression mechanism that sucks the film substrate and corrects the distortion of its shape in the vicinity of the back roll of the coating apparatus.

It is possible to arrange a layer having another function between the film base and the coating layer or on the surface of the coating layer. For example, it is possible to dispose a gas barrier layer or an easy-adhesion layer between the film substrate and the coating layer, or to dispose a hard coat layer or an abrasion-resistant layer on the surface of the coating layer.

This application is based on Japanese Patent Application No. 2013-170647 filed on August 20, 2013, the disclosures of which are referenced and incorporated as a whole.

10 coating device,
20 transport system,
22 film substrate,
24 Backroll,
30 Die coater,
32 laminates,
40 bars,
42 Front bar,
44 middle bar,
46 Backbar,
50 proximal end,
51 end face,
52 through holes,
53 pocket part 54 recess,
56 tip,
57 end face,
58 slit (gap),
60 side wall,
70 coating solution supply system,
72 preparation kettle,
73 Piping system,
74 pumps,
76 Preparation kettle,
77 Piping system,
78 pump,
81,82 pressure sensor,
D ₁ , D ₂ , D ₃ , D ₃₁ , D ₃₂ , D ₄ thickness,
F coating direction,
L, L ₁ , L ₂ coating solution,
W coating width direction,
μ ₁ and μ ₂ viscosities.

Claims

Having a plurality of stacked bars for simultaneous multi-layer application;
The bar
A tip that forms a gap between another adjacent bar;
A proximal end abutting against the another bar;
A pocket portion located between the distal end portion and the base end portion and having a recess that is a coating liquid reservoir,
A slide type die coater in which the coating liquid discharged from the gap flows down the end face of the tip,
The die coater whose Young's modulus of the material which comprises the said pocket part at least is 240 GPa or more.
The die coater according to claim 1, wherein the material has a Young's modulus of 280 GPa or more.
The die coater according to claim 1 or 2, wherein the material is a cemented carbide or a ceramic.
The die coater according to any one of claims 1 to 3, wherein at least the pocket portion is made of a single material.
The die coater according to any one of claims 1 to 4, wherein the pocket portion has a thickness of 15 mm or less.
The die coater according to claim 5, wherein the pocket portion has a thickness of 10 mm or less.
The die coater according to claim 5 or 6, wherein the pocket portion has a thickness of 5 mm or more.
The die coater according to any one of claims 1 to 7, wherein a length and a height of the bar are 1 m or more and 80 mm or more, respectively.
A die coater according to any one of claims 1 to 8,
A first container for holding a first coating liquid;
A second container for holding a second coating liquid;
A first coating liquid supply system for supplying the first coating liquid held in the first container to the die coater;
A second coating solution supply system for supplying the second coating solution held in the second container to the die coater;
A coating apparatus.
The pressure difference between the internal pressure of the concave portion of the pocket portion of the bar supplied with the second coating liquid and the internal pressure of the concave portion of the pocket portion of the bar supplied with the first coating liquid is 0.3 MPa or less. The coating device according to claim 9, which is set.
The coating apparatus according to claim 10, wherein the pressure difference is set to be 0.1 MPa or less.
The coating layer of the first coating liquid constitutes the high refractive index layer in the electromagnetic wave shielding film having a high refractive index layer and a low refractive index layer laminated alternately,
The coating apparatus according to any one of claims 9 to 11, wherein the coating layer of the second coating liquid constitutes the low refractive index layer.
A first coating liquid and a second coating liquid are supplied to the die coater according to any one of claims 1 to 8, and are discharged from a gap at a tip portion of the bar of the die coater. A coating method in which a coating layer of the first coating solution and a coating layer of the second coating solution are alternately laminated by causing the end surface to flow down, and a multilayer coating is simultaneously applied to the film substrate.
The pressure difference between the internal pressure of the concave portion of the pocket portion of the bar supplied with the second coating liquid and the internal pressure of the concave portion of the pocket portion of the bar supplied with the first coating liquid is 0.3 MPa or less. 14. The coating method according to 13.
The coating method according to claim 14, wherein the pressure difference is 0.1 MPa or less.
The coating layer of the first coating liquid constitutes the high refractive index layer in the electromagnetic wave shielding film having a high refractive index layer and a low refractive index layer laminated alternately,
The coating method according to any one of claims 13 to 15, wherein the coating layer of the second coating solution constitutes the low refractive index layer.
A method for producing an electromagnetic wave shielding film, comprising a step of simultaneously applying a high refractive index layer and a low refractive index layer by using the coating method according to claim 16.