JP2023177169A - Method for producing film - Google Patents

Abstract

To provide a method for producing a film capable of uniformly forming a wide and thin coating film on a substrate by using a slot die.SOLUTION: A method for producing a film, in which a slot die is used to form, on a substrate, a coating film having a width of 1,600 mm or more and a thickness of 30 μm or less, includes: an application step of applying a coating fluid to the substrate; and a drying step of drying the coating fluid applied to the substrate. A thickness of a shim of the slot die is 20 μm or more and 100 μm or less.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for manufacturing a film.

BACKGROUND ART Conventionally, a film manufacturing method is known in which a coating liquid is applied onto a base material using a slot die coater (see, for example, Patent Document 1).

JP 2021-34139 Publication

In the film manufacturing method as described in Patent Document 1 mentioned above, when forming a wide and thin film on a base material, it is desired to form it more uniformly.

The present invention provides a method for producing a film that can uniformly form a wide and thin coating on a substrate using a slot die.

The present invention [1] is a method for producing a film in which a film having a width of 1,600 mm or more and a thickness of 30 μm or less is formed on a base material using a slot die, and the method comprises using a coating liquid as a base material. A film comprising a coating step of coating the material and a drying step of drying the coating liquid applied to the base material, and the thickness of the shim of the slot die is 20 μm or more and 100 μm or less. Including manufacturing method.

The present invention [2] is characterized in that the slot die is arranged downstream of the first block in the conveyance direction of the base material and forms a slot between the first block and the second block. a block, and the shim disposed between the first block and the second block, and the second block includes a main body and a downstream side of the main body in the discharging direction of the coating liquid. The method includes a method for manufacturing a film according to [1] above, wherein the film has a protrusion that protrudes from the end face toward the downstream side in the discharge direction, and the protrusion amount of the protrusion is 10 μm or less.

The present invention [3] is characterized in that the slot die is arranged downstream of the first block in the transport direction of the base material and forms a slot between the first block and the second block. a block, and the shim disposed between the first block and the second block, wherein the second block is arranged in the discharging direction from the downstream end of the second block in the discharging direction of the coating liquid. has a slope that slopes away from the first block toward the upstream end of the second block, and an obtuse angle between the coating liquid discharge direction and the slope is 110° or more, It includes the method for producing a film according to [1] above, in which the angle is 170° or less.

The present invention [4] includes the method for producing a film according to the above [1], wherein the transport speed of the base material is 15 m/min or more and 30 m/min or less.

The present invention [5] includes the method for producing a film according to the above [1], wherein the solid content concentration of the coating liquid is 10% by mass or more and 50% by mass or less.

In the present invention [6], the coating liquid contains a polyfunctional oligomer and a trifunctional monomer, and the proportion of the polyfunctional oligomer in the coating liquid is 20% by mass or more and 70% by mass or less. The present invention includes the method for producing a film according to [1] above, wherein the proportion of the trifunctional monomer in the coating liquid is 20% by mass or more and 70% by mass or less.

The present invention [7] includes the method for producing a film according to the above [1], wherein the shim has an elastic modulus of 1500 MPa or more and 6000 MPa or less.

The present invention [8] includes the method for producing a film according to the above [1], wherein the shim is made of polyethylene terephthalate.

According to the film manufacturing method of the present invention, the thickness of the shim of the slot die is adjusted to 30 μm or more and 100 μm or less.

Therefore, a wide (width: 1600 mm or more) and thin (thickness: 30 μm or less) coating can be uniformly formed on the base material.

FIG. 1 is a cross-sectional view of the film. FIG. 2 is a schematic diagram of a film manufacturing system. FIG. 3 is a perspective view of the slot die. FIG. 4 is a cross-sectional view of the slot die shown in FIG. 3.

1. Method for manufacturing film In the method for manufacturing film F of the present invention, a slot die D is used to form a "wide" and "thin" coating C on a base material S. "Wide" means that the width is 1600 mm or more. "Thin" means that the thickness is 30 μm or less.

(1) Film First, film F will be explained. As shown in FIG. 1, the film F includes a base material S and a coating C.

The base material S has a sheet shape. The base material S has a first surface S1 and a second surface S2 in the thickness direction of the base material S. The base material S is made of thermoplastic resin.

Examples of the thermoplastic resin include acrylic resin, polyolefin resin, cyclic polyolefin resin, polyester resin, polycarbonate resin, polystyrene resin, polyamide resin, polyimide resin, and acetate resin. Examples of acetate resins include diacetylcellulose and triacetylcellulose.

In addition, the base material S may contain an additive. Examples of additives include antioxidants, stabilizers, reinforcing materials, ultraviolet absorbers, flame retardants, antistatic agents, colorants, fillers, plasticizers, lubricants, and fillers.

The coating C is arranged on the first surface S1 of the substrate S. The coating C covers the first surface S1 of the base material S. Functions of the coating C include, for example, anti-glare properties, anti-reflection properties and scratch resistance.

Coating C contains resin. Examples of the resin include thermosetting resins and thermoplastic resins. Examples of thermosetting resins include urethane resins and epoxy resins. Examples of thermoplastic resins include acrylic resins, urethane acrylic resins, and polyester resins.

Coating C may contain particles. Examples of the particles include oxides, carbonates, silicates, silicate minerals, and phosphates. Examples of the oxide include silicon oxide (silica), titanium oxide (titania), aluminum oxide (alumina), and zirconium oxide (zirconia). Examples of carbonates include calcium carbonate. Examples of silicates include calcium silicate, aluminum silicate, and magnesium silicate. Examples of silicate minerals include talc and kaolin. Examples of phosphates include calcium phosphate.

(2) Film Manufacturing System Next, a film F manufacturing system 1 for carrying out the film F manufacturing method will be described. As shown in FIG. 2, the film F manufacturing system 1 includes a coating device 2 including a slot die D and a drying device 3.

The coating device 2 coats the coating liquid onto the first surface S1 of the base material S (coating process). That is, the method for manufacturing film F includes a coating step. Note that the first surface S1 of the base material S may be subjected to surface treatment such as corona treatment or plasma treatment before the coating step.

In the coating step, the conveyance speed of the substrate S is, for example, 10 m/min or more, preferably 15 m/min or more, more preferably 20 m/min or more, and, for example, 40 m/min or less, preferably 35 m/min. /min, more preferably 30m/min or less.

When the conveyance speed of the substrate S is equal to or less than the above upper limit, the coating liquid can be uniformly applied to the substrate S. When the transport speed of the base material S is equal to or higher than the above lower limit value, the production efficiency of the film F can be improved.

The drying device 3 dries the coating liquid applied to the base material S (drying step). That is, the method for manufacturing film F includes a drying step. By drying the coating liquid, a coating C is formed on the base material S, and the above-described film F is obtained. Note that the coating C may be subjected to an ultraviolet curing treatment or a thermosetting treatment, if necessary.

2. Details of Coating Liquid The viscosity of the coating liquid is, for example, 100 mPa·s or less, preferably 50 mPa·s or less, more preferably 10 mPa·s or less, for example, 1 mPa·s or more. When the viscosity of the coating liquid is below the above upper limit, the coating liquid can be uniformly applied to the substrate S.

The surface tension of the coating liquid is, for example, 30 mN/m or more, preferably 35 mN/m or more, and, for example, 60 mN/m or less, preferably 55 mN/m or less.

The solid content concentration of the coating liquid is adjusted so that the viscosity of the coating liquid is equal to or less than the above upper limit. The solid content concentration of the coating liquid is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 40% by mass or more, and, for example, 50% by mass or less. , preferably 45% by mass or less.

The coating liquid contains a resin component and a solvent. The coating liquid contains the above-mentioned particles and additives, if necessary. The resin component may be the resin described above or a precursor of the resin described above.

Specifically, the coating liquid contains a polyfunctional oligomer, a polyfunctional monomer, a hydroxyl monomer, a photopolymerization initiator, the above particles, a surface tension modifier, and a thickener. The polyfunctional oligomer, polyfunctional monomer, and hydroxyl monomer are resin components (resin precursors), and the photopolymerization initiator, surface tension adjuster, and thickener are additives.

A polyfunctional oligomer has multiple ethylenically unsaturated groups. Examples of the ethylenically unsaturated group include an acrylic group, a methacryl group, and a vinyl group.

The weight average molecular weight of the polyfunctional oligomer is, for example, 300 or more, preferably 400 or more, and, for example, 5,000 or less, preferably 3,000 or less.

The functional group equivalent of the polyfunctional oligomer is, for example, 1 or more, preferably 2 or more, and is, for example, 6 or less, preferably 5 or less.

Examples of the polyfunctional oligomer include urethane acrylate and erythritol acrylate.

The proportion of the polyfunctional oligomer in the coating liquid is, for example, 20% by mass or more, preferably 30% by mass or more, and, for example, 70% by mass or less, preferably 50% by mass or less.

A polyfunctional monomer has multiple ethylenically unsaturated groups. Examples of the ethylenically unsaturated group include an acrylic group, a methacryl group, and a vinyl group.

Examples of the polyfunctional monomer include a condensate of pentaerythritol and acrylic acid.

The proportion of the polyfunctional monomer in the coating liquid is, for example, 20% by mass or more, preferably 30% by mass or more, and, for example, 70% by mass or less, preferably 50% by mass or less.

The hydroxyl monomer has one ethylenically unsaturated group and one hydroxyl group. Examples of the hydroxyl monomer include 4-hydroxybutyl acrylate and 2-hydroxyethyl acrylate.

The photopolymerization initiator radically polymerizes a polyfunctional oligomer, a polyfunctional monomer, and a hydroxyl monomer by UV irradiation. Examples of the photopolymerization initiator include benzophenone photopolymerization initiators, phosphine oxide photopolymerization initiators, oxime ester photopolymerization initiators, and cationic photopolymerization initiators.

The surface tension adjuster adjusts the surface tension of the coating liquid. Examples of the surface tension adjusting agent include cationic surfactants, anionic surfactants, nonionic surfactants, silicone leveling agents, and fluorine leveling agents.

The thickener adjusts the viscosity of the coating solution. Examples of thickeners include synthetic inorganic polymers, synthetic organic polymers, and natural organic polymers.

3. Details of Slot Die As shown in FIG. 3, the slot die D includes a first block 11, a second block 12, and a shim 13. The slot die D has a slot 10 between a first block 11 and a second block 12. The coating liquid is discharged from the slot 10.

(1) First block The first block 11 is arranged upstream of the second block 12 in the transport direction of the base material S. In this embodiment, the first block 11 is arranged below the second block 12. The first block 11 extends in the width direction of the base material S. As shown in FIG. 4, the first block 11 has an upstream end E1 and a downstream end E2 in the coating liquid discharge direction. Further, the first block 11 has a manifold 111, a flow path 112, a slot surface 113, and an inclined surface 114.

Manifold 111 is arranged between upstream end E1 and downstream end E2 in the coating liquid discharge direction. Manifold 111 extends in the width direction. The manifold 111 is open toward the second block 12.

The flow path 112 is arranged at the center of the first block 11 in the width direction. Flow path 112 communicates with manifold 111 . The coating liquid passes through the flow path 112 and enters the manifold 111 .

The slot surface 113 is an inner surface on the upstream side of the slot 10 in the conveying direction of the base material S. The slot surface 113 faces the second block 12. The slot surface 113 extends from the manifold 111 to the downstream end E2 in the coating liquid discharge direction. The slot surface 113 also extends in the width direction. Slot surface 113 is a flat surface.

The inclined surface 114 is the outer surface of the first block 11 on the upstream side in the conveying direction of the base material S. The inclined surface 114 is inclined with respect to the coating liquid discharge direction. Specifically, the slope 114 slopes away from the second block 12 from the downstream end E2 of the first block 11 toward the upstream end E1. The obtuse angle θ1 between the coating liquid discharge direction and the inclined surface 114 is, for example, 110° or more, preferably 140° or more, and is, for example, 170° or less, preferably 160° or less.

When the obtuse angle θ1 is equal to or greater than the lower limit value, it is possible to prevent the coating liquid from accumulating excessively on the upstream side of the protrusion 122 in the conveyance direction of the base material S. The protrusion 122 will be explained later. When the obtuse angle θ1 is less than or equal to the above upper limit value, it is possible to suppress the amount of the coating liquid that accumulates on the upstream side of the protruding portion 122 in the transport direction of the substrate S from becoming excessively small.

(2) Second block As shown in FIG. 3, the second block 12 is arranged downstream of the first block 11 in the conveyance direction of the base material S. In this embodiment, the second block 12 is arranged above the first block 11. The second block 12 extends in the width direction of the base material S. As shown in FIG. 4, the second block 12 has an upstream end E11 and a downstream end E12 in the coating liquid discharge direction. Further, the second block 12 has a main body portion 121 and a protrusion portion 122.

The main body portion 121 is the entire second block 12 excluding the protruding portion 122. The main body portion 121 has a slot surface 1211, an inclined surface 1212, and an end surface 1213.

The slot surface 1211 is the downstream inner surface of the slot 10 in the conveyance direction of the base material S. The slot surface 1211 faces the first block 11 . Specifically, slot surface 113 faces manifold 111 and slot surface 113. The slot surface 1211 extends in the coating liquid discharge direction. Slot surface 1211 extends parallel to slot surface 113. Note that the slot surface 1211 also extends in the width direction. Slot surface 1211 is a flat surface.

The inclined surface 1212 is the outer surface of the second block 12 on the downstream side in the conveyance direction of the base material S. The inclined surface 1212 is inclined with respect to the coating liquid discharge direction. Specifically, the slope 1212 slopes away from the first block 11 from the downstream end E12 of the second block 12 toward the upstream end E11. The obtuse angle θ2 between the coating liquid discharge direction and the inclined surface 1212 is, for example, 110° or more, preferably 140° or more, and is, for example, 170° or less, preferably 160° or less.

When the obtuse angle θ2 is equal to or greater than the lower limit value, it is possible to prevent the coating liquid from accumulating excessively on the upstream side of the protrusion 122 in the conveyance direction of the base material S. When the obtuse angle θ2 is less than or equal to the above upper limit value, it is possible to suppress the amount of the coating liquid that accumulates on the upstream side of the protruding portion 122 in the conveyance direction of the substrate S from becoming excessively small.

The end surface 1213 is a downstream end surface of the main body portion 121 in the coating liquid discharge direction. The end surface 1213 is arranged at the downstream end E12 of the second block. End surface 1213 is perpendicular to slot surface 1211. The end surface 1213 extends in the conveyance direction of the base material S.

The protruding portion 122 protrudes from the end surface 1213 toward the downstream side in the discharge direction. In other words, the protrusion 122 protrudes toward the base material S.

The amount of protrusion of the protruding portion 122 is, for example, 15 μm or less, preferably 10 μm or less, preferably 5 μm or less, and, for example, 1 μm or more.

When the amount of protrusion of the protrusion 122 is equal to or less than the upper limit value, the protrusion 122 can be prevented from touching the base material S. When the amount of protrusion of the protruding portion 122 is equal to or greater than the above lower limit value, the coating liquid can be stored upstream of the protruding portion 122 in the conveying direction of the substrate S, and even if the conveying speed of the substrate S increases, the coating will not be applied. The solution can be uniformly applied to the base material S.

The amount of protrusion of the protrusion 122 is, for example, 20% or less, preferably 10% or less, and, for example, 1% or more with respect to the distance between the end surface 1213 and the base material S in the discharge direction.

When the ratio of the amount of protrusion of the protrusion 122 to the distance between the end face 1213 and the base material S in the discharge direction is equal to or less than the above upper limit value, it is possible to suppress the protrusion 122 from touching the base material S. When the ratio of the protrusion amount of the protrusion 122 to the distance between the end face 1213 and the base material S in the discharge direction is equal to or greater than the lower limit value, the coating liquid is stored upstream of the protrusion 122 in the conveyance direction of the base material S. Therefore, even if the conveyance speed of the substrate S increases, the coating liquid can be uniformly applied to the substrate S.

(3) Shim As shown in FIGS. 3 and 4, the shim 13 is arranged between the first block 11 and the second block 12. The shim 13 adjusts the distance between the slot surface 113 of the first block 11 and the slot surface 1211 of the second block 12. In other words, the shim 13 adjusts the inner dimension of the slot 10 in the conveyance direction of the base material S.

The thickness of the shim 13 is 20 μm or more, preferably 30 μm or more, more preferably 60 μm or more, and, for example, 100 μm or less, preferably 80 μm or less.

If the thickness of the shim 13 is greater than or equal to the above lower limit, the thickness of the central portion of the coating C in the width direction of the base material S will increase excessively relative to the thickness of the end portion of the coating C in the width direction of the base material S. can be suppressed. If the thickness of the shim 13 is below the above upper limit value, the thickness of the end portion of the coating C in the width direction of the base material S will increase excessively relative to the thickness of the center portion of the coating C in the width direction of the base material S. can be suppressed.

Examples of the material for the shim 13 include stainless steel and polyethylene terephthalate.

The elastic modulus of the shim 13 is 1500 MPa or more and 6000 MPa or less. When the elastic modulus of the shim 13 is less than or equal to the above upper limit value, the shim 13 can be slightly deformed when the shim 13 is sandwiched between the first block 11 and the second block 12. As a result, the shim 13 is brought into contact with the first block 11 so that there is no gap between the first block 11 and the shim 13, and the shim 13 is brought into contact with the first block 11 so that no gap is created between the second block 12 and the shim 13. It can be brought into contact with the second block 12. As a result, it is possible to prevent the coating liquid from leaking between the first block 11 and the shim 13 or between the second block 12 and the shim 13. In addition, if the elastic modulus of the shim 13 is below the upper limit value, even if the shim 13 is slightly bent during storage, or if the shim 13 has minute scratches, the first block 11 and the first block 11 A shim 13 can be sandwiched between the first block 11 and the second block 12 so as to follow the second block 12. On the other hand, when the modulus of elasticity of the shim 13 is equal to or greater than the above lower limit value, when the shim 13 is sandwiched between the first block 11 and the second block 12, excessive deformation of the shim 13 can be suppressed.

Shim 13 preferably consists of polyethylene terephthalate. When the shim 13 is made of polyethylene terephthalate, the elastic modulus of the shim 13 can be set within the above range. Moreover, when the shim 13 is made of polyethylene terephthalate, the shim 13 can be easily processed.

4. Uniformity of the film By applying the above-mentioned coating liquid to the base material S using the above-mentioned slot die D and drying it, a film F having a uniform thickness of the film C across the width direction of the base material S is manufactured. be able to.

In the obtained film F, in the width direction of the base material S, the difference between the thickness of the center part of the coating C and the thickness of the edge part of the coating C is, for example, 2.5 μm or less, preferably 2.0 μm or less. , more preferably 1.5 μm or less, more preferably 1.0 μm or less, and even more preferably 0.5 μm or less. Note that the lower limit of the difference between the thickness of the central portion of the coating C and the thickness of the end portions of the coating C is not limited. The difference between the thickness of the central portion of the coating C and the thickness of the end portions of the coating C may be 0 μm.

4. Effects According to the method for manufacturing the film F, the thickness of the shim 13 of the slot die D is adjusted to be 30 μm or more and 100 μm or less.

Therefore, a wide (width of 1600 mm or more) and thin (thickness of 30 μm or less) coating C can be uniformly formed on the base material S.

Specifically, when the viscosity of the coating liquid is 100 mPa or less, the difference between the thickness of the center portion of the coating C and the thickness of the edge portion of the coating C in the width direction of the substrate S is 2.5 μm or less. Can be done.

Next, the present invention will be explained based on Examples and Comparative Examples. The invention is not limited by the examples below. In addition, specific numerical values of physical property values, parameters, etc. used in the following description are the corresponding upper limit values of physical property values, parameters, etc. described in the above "Detailed Description" (a numerical value defined as "less than or equal to" or "less than") or a lower limit value (a numerical value defined as "more than" or "greater than").

1. Manufacture of coating liquid The following materials were blended with toluene to obtain a coating liquid. The solid content of the coating liquid was 42% by mass, and the viscosity of the coating liquid was 6 mPa·s.

Multifunctional oligomer:
NK oligomer UA-53H-80BK (manufactured by Shin Nakamura Chemical Co., Ltd.) 50 parts by mass Polyfunctional monomer:
Viscoat #300 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 50 parts by mass Hydroxyl group monomer:
4-Hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 20 parts by mass Photopolymerization initiator:
Omnirad907 (manufactured by IGM Resin) 5 parts by mass Surface tension regulator GRANDIC PC4100 (manufactured by DIC) 1 part by mass Silica particles Techpolymer SSX-103DXE (manufactured by Sekisui Plastics Co., Ltd.) 0.5 parts by mass Thickener Smectone-SAN Solution (manufactured by Nitto Denko Corporation) 1.5 parts by mass 2. Production of film The coating liquid was applied to the base material (material: acrylic film) using the slot die (block height: 76 mm) shown in Figure 3 under the conditions shown in Tables 1 to 3, and the coating solution was heated at 95°C. , and dried for 1 minute to obtain films of each Example and each Comparative Example having an acrylic urethane resin coating on the base material.

The thickness of the resulting film was measured at five locations in the width direction of the base material (the center, one end, the other end, between one end and the center, and between the other end and the center). The difference between the thickness and the minimum thickness was calculated. The results are shown in Table 1.

In addition, the appearance of the film was evaluated based on the following criteria. The results are shown in Tables 1 to 3.

<Appearance evaluation criteria>
A: There is no appearance defect at all in visual inspection.

B: Slight unevenness is visible in visual inspection, but it can be used as a product.

C: Appearance defects are visible in visual inspection, but it can be used as a product.

D: Appearance defects occur throughout the product and it cannot be used as a product.

D Slot die 10 Slot 11 1st block 12 2nd block 13 Shim

Claims (8)

A method for producing a film in which a film having a width of 1600 mm or more and a thickness of 30 μm or less is formed on a base material using a slot die, the method comprising:
a coating process of applying a coating liquid to a base material;
a drying step of drying the coating liquid applied to the base material,
A method for manufacturing a film, wherein the thickness of the shim of the slot die is 20 μm or more and 100 μm or less. The slot die includes a first block, a second block that is disposed downstream of the first block in the conveying direction of the base material and forms a slot between the first block, and the first block. and the shim disposed between the shim and the second block,
The second block is
The main body and
a protruding portion that protrudes from a downstream end face of the main body portion toward the downstream side in the discharging direction of the coating liquid;
The method for producing a film according to claim 1, wherein the protrusion amount of the protrusion is 10 μm or less. The slot die includes a first block, a second block that is disposed downstream of the first block in the conveying direction of the base material and forms a slot between the first block, and the first block. and the shim disposed between the shim and the second block,
The second block is
having an inclined surface that slopes away from the first block from the downstream end of the second block in the discharging direction of the coating liquid toward the upstream end of the second block in the discharging direction;
The method for producing a film according to claim 1, wherein an obtuse angle between the discharge direction of the coating liquid and the inclined surface is 110° or more and 170° or less. The method for manufacturing a film according to claim 1, wherein the conveyance speed of the base material is 15 m/min or more and 30 m/min or less. The method for producing a film according to claim 1, wherein the coating liquid has a solid content concentration of 10% by mass or more and 50% by mass or less. The coating liquid contains a polyfunctional oligomer and a trifunctional monomer,
The proportion of the polyfunctional oligomer in the coating liquid is 20% by mass or more and 70% by mass or less,
The method for producing a film according to claim 1, wherein the proportion of the polyfunctional oligomer in the coating liquid is 20% by mass or more and 70% by mass or less. The method for producing a film according to claim 1, wherein the shim has an elastic modulus of 1500 MPa or more and 6000 MPa or less. The method for manufacturing a film according to claim 1, wherein the shim is made of polyethylene terephthalate.