Manufacturing method of laminated film

Abstract

To provide a manufacturing method of a laminate film capable of realizing a product film having an excellent appearance while protecting a surface of the product film.SOLUTION: The manufacturing method of a laminate film includes a bonding process. In the bonding process, a protective film and a product film are passed between a first bonding roller and a second bonding roller and are bonded together, by an adhesive layer. At 25°C and 55%RH, a storage elastic modulus of the adhesive layer is 1.0×103 Pa to 9.9×105 Pa. Thickness of the adhesive layer is 5 μm or more. Thickness T1 of the protective film exceeds 1.0 with regard to thickness T2 of the adhesive layer. At 25°C, hardness R2 of the second bonding roller on a side of the product film exceeds 1.0 with regard to hardness R1 of the first bonding roller on a side of the protective film.SELECTED DRAWING: Figure 1

Description

[Technical Field] 【0001】 This invention relates to a method for manufacturing a laminated film. [Background technology] 【0002】 Traditionally, resin films have been widely used in various industrial products. One example of such resin films is optical films used in image display devices. Optical films require stricter standards regarding scratches and dirt than resin films used in other applications (e.g., packaging films). Therefore, it is known that a protective film is temporarily applied to the surface of optical films during transportation to suppress scratches and dirt on the optical film surface. As such a protective film, it has been proposed to use, for example, a polyester film with excellent mechanical strength and transparency (see, for example, Patent Document 1). [Prior art documents] [Patent Documents] 【0003】 [Patent Document 1] Japanese Patent Publication No. 2006-176685 [Overview of the project] [Problems that the invention aims to solve] 【0004】 In recent years, the development of new applications for image display devices has been progressing. Depending on the application of the image display device, a significantly superior appearance is required for the resin film (typically optical film) compared to conventional methods. In particular, appearance defects at levels that were not problematic until now may have a substantial negative impact on the performance of the image display device. The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a method for manufacturing a laminated film that can protect the surface of the product film and realize a product film having an excellent appearance. [Means for solving the problem] 【0005】 [1] A method for manufacturing a laminated film according to an embodiment of the present invention includes a lamination step. In the lamination step, a protective film and a product film are bonded together by an adhesive layer by passing them between a first lamination roll and a second lamination roll. In the lamination step, the first lamination roll is located on the side of the product film relative to the protective film, and the second lamination roll is located on the side of the protective film relative to the product film. The storage modulus of the adhesive layer at 25°C and 55% relative humidity is 1.0 × 10⁻⁶ 3 Pa~9.9×10 5 The hardness is Pa. The thickness T1 of the adhesive layer is 5 μm or more. The thickness T1 of the adhesive layer is 1.0 or less relative to the thickness T2 of the protective film. At 25°C, the hardness R2 of the second laminating roll is greater than 1.0 relative to the hardness R1 of the first laminating roll. [Effects of the Invention] 【0006】 According to embodiments of the present invention, it is possible to realize a product film that can protect the surface of the product film and has an excellent appearance. [Brief explanation of the drawing] 【0007】 [Figure 1] Figure 1 is a schematic diagram illustrating a method for manufacturing a laminated film according to one embodiment of the present invention. [Modes for carrying out the invention] 【0008】 The embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. In addition, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the embodiments in order to make the explanation clearer, but these are merely examples and do not limit the interpretation of the present invention. 【0009】 (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated using the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). 【0010】 A. Outline of the manufacturing method for laminated films Figure 1 is a schematic diagram illustrating a method for manufacturing a laminated film according to one embodiment of the present invention. 【0011】 A method for manufacturing a laminated film according to one embodiment includes a lamination step. In the lamination step, the protective film 1 and the product film 2 are bonded together by passing them between a first lamination roll 3a and a second lamination roll 3b using an adhesive layer 5. In the lamination step, the first lamination roll 3a is located on the side of the protective film 1 away from the product film 2, and the second lamination roll 3b is located on the side of the product film 2 away from the protective film 1. The storage modulus of the adhesive layer 5 at 25°C and 55% RH (relative humidity) is 1.0 × 10⁻⁶. 3 Pa~9.9×10 5 The hardness is Pa. The thickness T1 of the adhesive layer 5 is 5 μm or more. The ratio of the thickness T1 of the adhesive layer 5 to the thickness T2 of the protective film 1 (T1 / T2) is 1.0 or less. At 25°C, the hardness R2 of the second laminating roll 3b to the hardness R1 of the first laminating roll 3a (R2 / R1) exceeds 1.0. The inventor has discovered that when the product film and the protective film are bonded using the first bonding roll and the second bonding roll, indentations may be formed on the product film. Therefore, as a result of intensive studies on the formation of indentations in the product film, it was estimated that the indentations in the product film are formed by the transfer of appearance defects (such as fish eyes, burns, wrinkles) of the protective film to the product film during the bonding process. The inventor further studied this finding and found that if the thickness of the adhesive layer for attaching the product film and the protective film and the hardness of each of the first bonding roll and the second bonding roll are in a specific relationship, even when the protective film is attached to the product film by the first bonding roll and the second bonding roll, the indentations in the product film can be suppressed. Specifically, when the thickness T1 of the adhesive layer is 5 μm or more and the hardness R2 of the second bonding roll with respect to the hardness R1 of the first bonding roll (R2 / R1) exceeds 1.0, the transfer of appearance defects of the protective film to the product film can be suppressed. Therefore, the indentations in the product film can be suppressed. Also, according to one embodiment, since the thickness T1 of the adhesive layer with respect to the thickness T2 of the protective film (T1 / T2) is 1.0 or less and the storage elastic modulus of the adhesive layer is 1.0×10 3 Pa or more, the occurrence of wrinkles in the product film during the conveyance of the laminated film can be suppressed, and the peeling of the protective film from the product film can be suppressed. As a result, while the protective film can be attached to the product film to protect the surface of the product film, a product film having an excellent appearance can be realized. 【0012】 The storage elastic modulus of the adhesive layer 5 at 25°C and 55% RH is preferably 1.0×10 3 Pa to 9.0×10 5 Pa, and more preferably 8.0×10 4 Pa to 1.2×10 5 Pa. When the storage elastic modulus of the adhesive layer is within such a range, the peeling of the protective film from the product film can be stably suppressed. The storage elastic modulus of the adhesive layer is measured in accordance with JIS K 6868, for example, in shear mode, at a constant temperature of 25°C, and at a frequency of 1 Hz. 【0013】 The thickness T1 of the adhesive layer 5 with respect to the thickness T2 of the protective film 1 (T1 / T2) is preferably 0.90 or less, more preferably 0.80 or less, and even more preferably 0.50 or less. When the thickness ratio (T1 / T2) of the protective film and the adhesive layer is in such a relationship, it is possible to stably suppress the occurrence of wrinkles in the product film during the conveyance of the laminated film, and it is possible to improve the conveyance property of the laminated film. On the other hand, the thickness T1 of the adhesive layer 5 with respect to the thickness T2 of the protective film 1 (T1 / T2) is, for example, 0.10 or more, preferably 0.20 or more, and more preferably 0.30 or more. When the thickness ratio (T1 / T2) of the protective film and the adhesive layer is in such a relationship, it is possible to stably suppress the indentation in the product film. 【0014】 The thickness T1 of the adhesive layer 5 is preferably 8 μm or more, more preferably 10 μm or more. When the adhesive layer has such a thickness, it is possible to more stably suppress the indentation in the product film. On the other hand, the thickness T1 of the adhesive layer 5 is, for example, 50 μm or less, preferably 40 μm or less, and more preferably 35 μm or less. When the adhesive layer has such a thickness, it is possible to more stably suppress the occurrence of wrinkles in the product film during the conveyance of the laminated film. 【0015】 The thickness T2 of the protective film 1 is, for example, 7 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more. On the other hand, the thickness T2 of the protective film 1 is, for example, 80 μm or less, preferably 60 μm or less, and more preferably 40 μm or less. When the protective film has such a thickness, it is possible to stably adjust the thickness ratio (T1 / T2) of the protective film and the adhesive layer within the above range. 【0016】 At 25°C, the ratio of the hardness R2 of the second laminating roll 3b to the hardness R1 of the first laminating roll 3a (R2 / R1) is preferably 1.01 or higher, more preferably 1.05 or higher, and even more preferably 1.08 or higher. When the hardness ratio (R2 / R1) of the first laminating roll and the second laminating roll has this relationship, dents in the product film can be suppressed more stably. On the other hand, at 25°C, the hardness R2 (R2 / R1) of the second bonding roll 3b relative to the hardness R1 of the first bonding roll 3a is, for example, 2.0 or less, preferably 1.8 or less, and more preferably 1.60 or less. 【0017】 The first laminating roll 3a on the protective film 1 side is typically softer than the second laminating roll 3b on the product film 2 side. The hardness R1 of the first bonding roll 3a at 25°C is, for example, 30 to 120, preferably 50 to 90, and more preferably 60 to 80. The hardness R2 of the second bonding roll 3b at 25℃ is, for example, 50 to 130, preferably 70 to 110, and more preferably 85 to 95. The hardness of the laminating roll is measured using durometer hardness, for example, in accordance with JIS K 6253. 【0018】 At 25°C, the indentation modulus E2 of the product film 2 relative to the indentation modulus E1 of the protective film 1 (E2 / E1) is, for example, 0.30 or more, preferably 0.50 or more, and more preferably 0.60 or more. On the other hand, at 25°C, the indentation modulus E2 of the product film 2 relative to the indentation modulus E1 of the protective film 1 (E2 / E1) is, for example, 1.40 or less, or for example 1.20 or less, or for example 1.00 or less, or for example 0.80 or less. Even with such a relationship in the indentation modulus ratio (E2 / E1) between the protective film and the product film, according to the above embodiment, a product film with an excellent appearance can be stably realized. 【0019】 The protective film 1 may be softer than the product film 2, or it may be harder than the product film 2. In one embodiment, the protective film 1 is harder than the product film 2. The indentation modulus E1 of the protective film 1 at 25°C is, for example, 0.5 GPa to 6.0 GPa, preferably 1.5 GPa to 4.5 GPa, and more preferably 2.0 GPa to 4.0 GPa. The indentation modulus E2 of the product film 2 at 25°C is, for example, 1.0 GPa to 5.0 GPa, preferably 1.0 GPa to 4.0 GPa, more preferably 2.5 GPa to 3.5 GPa, and particularly preferably 2.0 GPa to 3.2 GPa. The indentation modulus of the film is measured, for example, in accordance with ISO 14577. 【0020】 B. Details of the manufacturing method for laminated films The following describes the details of the manufacturing method for laminated films. In one embodiment of the method for manufacturing a laminated film, first, a protective film 1 and a product film 2 are prepared. 【0021】 B-1. Product Film Product film 2 may have any suitable configuration. Typically, product film 2 has a long, rectangular shape. Product film 2 may have a single-layer structure or a laminated structure in which two or more layers are stacked. In the illustrated example, product film 2 has a single-layer structure. The thickness of product film 2 is, for example, 10 μm to 100 μm, preferably 15 μm to 80 μm. 【0022】 Product film 2 is typically composed of any suitable resin material. Examples of resin materials constituting product film 2 include polycarbonate (PC) resins, polyvinyl acetal resins, cycloolefin (COP) resins, (meth)acrylic resins, cellulose ester resins, cellulose resins, polyester resins, polyester carbonate resins, olefin resins, and polyurethane resins. (Meth)acrylic resins refer to acrylic resins and / or methacrylic resins. These resin materials can be used individually or in combination. 【0023】 Among the resin materials constituting the product film 2, PC-based resins, COP-based resins, and (meth)acrylic resins are preferred, with PC-based resins being more preferred. When the product film is made of such resin materials, dents in the product film can be reliably suppressed. 【0024】 Examples of PC resins include PC resins containing structural units derived from dihydroxy compounds. Specific examples of dihydroxy compounds include 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-hydroxy-3-ethylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-propylphenyl)fluorene, 9,9-bis(4-hydroxy-3-isopropylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-sec-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-tert-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-cyclohexylphenyl)fluorene, 9,9-bis(4-hydroxy-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis( 4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexyl Examples include phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, and 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene.In addition to the structural units derived from the above-mentioned dihydroxy compounds, PC resins may also contain structural units derived from dihydroxy compounds such as isosorbide, isomannide, isoidet, spiroglycol, dioxane glycol, diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), cyclohexanedimethanol (CHDM), tricyclodecanedimethanol (TCDDM), and bisphenols. 【0025】 Details of the PC resin described above are described, for example, in Japanese Patent Publication No. 2012-67300 and Japanese Patent No. 3325560. The descriptions in said patent documents are incorporated herein by reference. 【0026】 Examples of product film 2 include optical films such as phase difference films, and phase difference films are preferred. 【0027】 A phase difference film is typically prepared by stretching a resin film made of the resin material described above in a predetermined direction. Any suitable stretching method can be employed. A phase difference film typically has a slow axis in the stretching direction. In one embodiment, the refractive index of the phase difference film is given by nx > ny. 【0028】 The phase difference film may function as a λ / 4 plate. When the phase difference film functions as a λ / 4 plate, the in-plane phase difference Re(550) of the phase difference film is, for example, 100 nm to 180 nm, preferably 135 nm to 155 nm. Furthermore, the phase difference film may function as a λ / 2 plate. When the phase difference film functions as a λ / 2 plate, the in-plane phase difference Re(550) of the phase difference film is, for example, 230 nm to 310 nm, preferably 250 nm to 290 nm. 【0029】 B-2. Protective film The protective film 1 can protect the surface of the product film 2 by being attached to it. The protective film 1 may have any suitable configuration. Typically, the protective film 1 has a long shape. The protective film 1 may have a single-layer structure or a laminated structure in which two or more layers are laminated. In the illustrated example, the protective film 1 has a single-layer structure. 【0030】 The protective film 1 is typically composed of any suitable resin material. Examples of resin materials that make up the protective film 1 include olefin resins, COP resins, polyester resins, cellulose resins, PC resins, (meth)acrylic resins, polyvinyl acetal resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, acetate resins, thermosetting resins, and UV-curing resins. These resin materials can be used individually or in combination. 【0031】 Among the resin materials constituting the protective film 1, preferred examples include COP resins and polyester resins, and more preferably polyethylene terephthalate (PET). When the protective film is made of such resin materials, the protective film can stably protect the surface of the product film. 【0032】 B-3.Adhesive layer In one embodiment, an adhesive layer 5 is pre-laminated on the protective film 1 and / or the product film 2. In the illustrated example, the adhesive layer 5 is laminated on the protective film 1 but not on the product film 2. Hereinafter, the protective film 1 with the adhesive layer 5 laminated on it may be referred to as the adhesive-layered protective film 6. 【0033】 Any suitable method can be used for laminating the adhesive layer 5. The adhesive layer 5 may be formed on the surface of the film (protective film 1 and / or product film 2) by direct printing or by transfer printing. In the case of direct printing, the adhesive composition is applied directly to the surface of the film to form the adhesive layer 5. In the case of transfer printing, the adhesive composition is applied to the surface of a release liner to form the adhesive layer 5, and then the adhesive layer 5 is attached to the film. 【0034】 The adhesive layer 5 may be composed of any suitable adhesive. Examples of adhesives include (meth)acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination and blending ratio of monomers forming the base resin of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., an adhesive with desired properties according to the purpose can be prepared. The base resin of the adhesive may be used alone or in combination of two or more types. Among such adhesives, (meth)acrylic adhesives ((meth)acrylic adhesive compositions) are preferred. 【0035】 (Meth)acrylic adhesive compositions typically contain (meth)acrylic polymers as their main component. The content of (meth)acrylic polymers in the solid content of the adhesive composition is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more. On the other hand, the upper limit of the content of (meth)acrylic polymers in the solid content of the adhesive composition is typically 100% by mass. 【0036】 (Meth)acrylic polymers contain alkyl (meth)acrylate as the main component as monomer units. In (meth)acrylic polymers, the content of constituent units derived from alkyl (meth)acrylate is, for example, 70% by mass or more, preferably 80% by mass or more, and more preferably 85% by mass or more. On the other hand, the content of constituent units derived from alkyl (meth)acrylate is, for example, 98% by mass or less, preferably 95% by mass or less. Examples of alkyl groups in alkyl (meth)acrylates include linear or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is preferably 3 to 9, and more preferably 3 to 6. Among alkyl (meth)acrylates, butyl acrylate is a preferred example. 【0037】 Examples of monomers (copolymer monomers) constituting (meth)acrylic polymers include alkyl (meth)acrylates, carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic vinyl monomers. Representative examples of copolymer monomers include acrylic acid, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, benzyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. Copolymer monomers can be used alone or in combination. Among the copolymer monomers, acrylic acid, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and benzyl acrylate are preferred, more preferably acrylic acid and 2-hydroxyethyl acrylate, and even more preferably a combination of acrylic acid and 2-hydroxyethyl acrylate. In (meth)acrylic polymers, the content of constituent units derived from copolymer monomers is, for example, 30% by mass or less, preferably 20% by mass or less, and more preferably 15% by mass or less. On the other hand, the content of constituent units derived from copolymer monomers is, for example, 0% by mass or more, or for example, 3% by mass or more. 【0038】 The weight-average molecular weight Mw of the (meth)acrylic polymer is, for example, 200,000 to 3,000,000, preferably 1,000,000 to 2,500,000, more preferably 1,200,000 to 2,500,000, and even more preferably 1,500,000 to 2,500,000. The weight-average molecular weight Mw can be calculated, for example, from the results of GPC measurement by styrene conversion. If the weight-average molecular weight Mw is within this range, an adhesive layer with excellent durability (especially heat resistance) can be obtained. The weight-average molecular weight Mw (Mw / Mn) of the (meth)acrylic polymer relative to the number-average molecular weight Mn is, for example, 1.0 or more, preferably 2.0 or more, and for example, 5.0 or less, preferably 4.0 or less. 【0039】 The acrylic adhesive composition preferably contains a silane coupling agent and / or a crosslinking agent. Examples of silane coupling agents include epoxy group-containing silane coupling agents. The content of the silane coupling agent is, for example, 0.001 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the (meth)acrylic polymer. 【0040】 Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. The crosslinking agents can be used alone or in combination. Among the crosslinking agents, isocyanate-based crosslinking agents are preferred. The content of the crosslinking agent is, for example, 0.01 parts by mass or more, preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of (meth)acrylic polymer. On the other hand, the content of the crosslinking agent is, for example, 15 parts by mass or less, preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and particularly preferably 1.0 part by mass or less. 【0041】 B-4. First laminating roll and second laminating roll The first bonding roll 3a has any suitable configuration. Typically, the first bonding roll 3a has a cylindrical shape extending in a predetermined direction. The outer diameter of the first bonding roll 3a is, for example, 100 mm to 500 mm, preferably 150 mm to 300 mm. The outer surface of the first bonding roll 3a is softer than the outer surface of the second bonding roll 3b. The outer surface of the first bonding roll 3a has the hardness R1 described above. 【0042】 The first laminating roll 3a is made of any suitable material. Examples of materials for the first laminating roll 3a include metals, metalloids, and rubber, with rubber being preferred. Preferred rubbers include silicone rubber, butyl rubber, and SEBS, with silicone rubber being more preferred. 【0043】 In one embodiment, the first bonding roll 3a comprises a roll body having a cylindrical shape and a shaft inserted into the roll body. The roll body is typically made of the rubber described above. The range of the outer diameter of the roll body is typically the same as the range of the outer diameter of the first laminated roll described above. The outer surface of the roll body is softer than the outer surface of the second laminated roll 3b. The outer surface of the roll body has the hardness R1 described above. The shaft is typically made of the metals mentioned above. When the shaft is inserted into the roll body, both ends of the shaft are exposed from the roll body. 【0044】 The second bonding roll 3b has any suitable configuration. Typically, the second bonding roll 3b has a cylindrical shape extending in a predetermined direction. The outer diameter of the second bonding roll 3b is, for example, 100 mm to 500 mm, preferably 150 mm to 300 mm. The outer surface of the second bonding roll 3b has the hardness R2 described above. 【0045】 The second bonding roll 3b is made of any suitable material. Examples of materials for the second bonding roll 3b include metals and metalloids, with metals being preferred. Examples of metals include iron, copper, aluminum, chromium, nickel, and their alloys. Among metals, iron is preferred. 【0046】 In one embodiment, the second bonding roll 3b comprises a cylindrical shaft and a plating film provided on the outer surface of the shaft. The shaft is typically made of the metal described above. The plating film is typically made of an alloy of the metal described above. In one embodiment, the plating film is applied over the entire outer surface of the shaft. The thickness of the plating film is arbitrarily and appropriately adjusted so that the hardness R2 of the outer surface of the second bonding roll 3b falls within the range described above. 【0047】 The second laminating roll 3b is positioned radially opposite to the first laminating roll 3a. The outer surfaces of the first laminating roll 3a and the second laminating roll 3b are typically in contact with each other before the protective film 1 and the product film 2 are supplied between them. 【0048】 In one embodiment, either the first laminating roll 3a or the second laminating roll 3b is pressed toward the other. This typically forms a nip N between the first laminating roll 3a and the second laminating roll 3b. The nip pressure (pressing force of the bonding roll) is, for example, 1 MPa to 100 MPa, preferably 5 MPa to 50 MPa. 【0049】 B-5. Details of the lamination process In the lamination process, the protective film 1 and the product film 2 are supplied so as to pass through the nip N. In one embodiment, the adhesive-coated protective film 6 and the product film 2 are supplied so as to pass through the nip N. In the illustrated example, the protective film 1 (adhesive-coated protective film 6) is supplied between the first laminating roll 3a and the second laminating roll 3b via the first conveyor roller 41. The product film 2 is supplied between the first laminating roll 3a and the second laminating roll 3b via the second conveyor roller 42. Each of the first conveyor roller 41 and the second conveyor roller 42 is movable relative to the first laminating roll 3a. 【0050】 In the lamination process, the tension applied to the protective film 1 is, for example, 50 N / m to 500 N / m, preferably 100 N / m to 300 N / m. When the tension applied to the protective film in the lamination process is within this range, the protective film and the product film can be smoothly bonded together, and the occurrence of dents on the product film can be more reliably suppressed. The tension on the protective film 1 can be adjusted as appropriate by moving the first transport roller 41 relative to the first laminating roll 3a. 【0051】 In the lamination process, the tension applied to the product film 2 is, for example, 50 N / m to 500 N / m, preferably 100 N / m to 300 N / m. When the tension applied to the product film in the lamination process is within this range, the protective film and the product film can be bonded more smoothly, and the occurrence of dents on the product film can be suppressed more reliably. The tension on the product film 2 can be adjusted as appropriate by moving the second transport roller 42 relative to the first laminating roll 3a. 【0052】 The supply speed (line speed) of the protective film 1 and the product film 2 in the lamination process is, for example, 5 m / min to 50 m / min, preferably 15 m / min to 30 m / min. 【0053】 When protective film 1 passes between the first laminating roll 3a and the second laminating roll 3b (nip N), it typically comes into contact with the outer surface of the first laminating roll 3a. Similarly, when product film 2 passes between the first laminating roll 3a and the second laminating roll 3b (nip N), it typically comes into contact with the outer surface of the second laminating roll 3b. At this time, the protective film 1 and the product film 2 are properly pressed together by the first laminating roll 3a and the second laminating roll 3b. As a result, the protective film 1 and the product film 2 are pressed together by the adhesive layer 5. 【0054】 A long laminated film 100 is manufactured as described above. In the illustrated example, the laminated film 100 is wound up as needed after passing through the third conveyor roller 43. The third conveyor roller 43 may be movable relative to the first laminating roll 3a. 【0055】 C. Laminated film The laminated film 100 in the illustrated example comprises a protective film 1, an adhesive layer 5, and a product film 2 in this order. Such a laminated film 100 can be used in any suitable application. The product film 2 may be used with the protective film 1 attached (i.e., as part of the laminated film 100), or it may be used after the protective film 1 and adhesive layer 5 have been peeled off. Preferably, the product film 2 is used after the protective film 1 and adhesive layer 5 (adhesive-coated protective film 6) have been peeled off. The product film 2 can typically be used in optical applications such as image display devices. In particular, the product film 2 is suitable for use in image display devices such as smartphones and tablet PCs because it significantly suppresses scratches and dirt and has an excellent appearance. [Examples] 【0056】 The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on mass. Furthermore, the measurement methods for each characteristic in the examples and comparative examples are as follows. 【0057】 (1) Measurement of the indentation modulus of the protective film and the product film, respectively. The indentation modulus of the protective film and product film used in the examples and comparative examples was measured by the nanoindenter method in accordance with ISO 14577 under the following measurement conditions. The indentation modulus E1 of the protective film, the indentation modulus E2 of the product film, and E2 / E1 are shown in Table 1. Equipment: Nanoindenter (manufactured by nanomechanics) Sample size: 10 x 10 mm Indenter: square pyramid indenter Measurement temperature: 25℃ Measurement humidity: 55%RH Maximum indentation load: 25mN Indentation speed: 100nm / sec Hold time: 2 seconds Load unloading speed: 2.5mN / sec Calculation method: Compliant with ISO 14577 【0058】 (2) Measurement of the storage modulus of the adhesive layer The storage modulus of the adhesive layers used in the examples and comparative examples was measured in accordance with JIS K 6868 under the following measurement conditions. The storage modulus of the adhesive layers is shown in Table 1. Measurement temperature: 25℃ (constant temperature) Measurement humidity: 55%RH Measurement mode: Shear Frequency: 1Hz 【0059】 (3) Measurement of the hardness of the first and second laminating rolls. The hardness of the first and second laminating rolls used in the examples and comparative examples was measured in accordance with JIS K 6253. The hardness R1 of the first laminating roll, the hardness R2 of the second laminating roll, and R2 / R1 are shown in Table 1. 【0060】 (4) Appearance determination of laminated film The appearance of the laminated films prepared in the examples and comparative examples was evaluated by laminating them onto an aluminum reflector after integrating them with a polarizing plate, and checking their appearance under fluorescent light reflection, according to the following criteria. The results are shown in Table 1. ○: No dent shape is visible. ×: The shape of the dent is visible. 【0061】 (5) Evaluation of the transportability of laminated films The transportability of the laminated films prepared in the examples and comparative examples was evaluated according to the following criteria, based on the degree of contamination of the production line or the presence or absence of film breakage. The results are shown in Table 1. ○: No process contamination or film breakage. ×: Process contamination and / or film breakage present. 【0062】 <<Preparation of adhesive>> <Preparation Example 1> In a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirring device, 94.9 parts by mass of butyl acrylate, 5 parts by mass of acrylic acid, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 0.3 parts by mass of dibenzoyl peroxide per 100 parts by mass of the total monomers (solids) were added together with ethyl acetate. The mixture was reacted at 60°C for 7 hours under a nitrogen gas stream, and then ethyl acetate was added to the reaction solution to obtain a solution containing an acrylic polymer with a weight-average molecular weight of 2.2 million and a dispersion ratio of 3.9 (solids concentration 30% by mass). For every 100 parts by mass of the solids of the acrylic polymer solution, 0.6 parts by mass of trimethylolpropanetylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.: Coronate L) and 0.075 parts by mass of γ-glycidoxypropyl methoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.: KBM-403) were added to obtain an adhesive solution. The above solution was diluted with ethyl acetate to a solids concentration of 15% by mass to prepare an adhesive coating solution. A 38 μm polyethylene terephthalate (PET) film (MRF38, manufactured by Mitsubishi Chemical Polyester Films Co., Ltd.) that had been treated with silicone was coated on one side with the adhesive coating solution prepared above using a fountain die coater to a coating thickness of 134.0 μm. It was then dried at 155°C for 1 minute, resulting in a storage modulus of 1.13 × 10⁻⁶. 5 An adhesive layer with a density of Pa was obtained. The thickness T1 of the adhesive layer was 15 μm. 【0063】 <Preparation Example 2> Except for adding 89.9 parts by mass of butyl acrylate, 10 parts by mass of acrylic acid, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 0.3 parts by mass of dibenzoyl peroxide to 100 parts by mass of the total monomers (solids) together with ethyl acetate, and reacting under a nitrogen gas stream at 60°C for 6 hours, ethyl acetate was added to the reaction solution to obtain a solution containing an acrylic polymer with a weight-average molecular weight of 1.7 million and a dispersion ratio of 3.9 (solids concentration 30% by mass), the preparation was carried out in the same manner as in Preparation Example 1, with a storage modulus of 1.13 × 10⁻⁶. 3 An adhesive layer with a density of Pa was obtained. The thickness T1 of the adhesive layer was 38 μm. 【0064】 <Preparation Example 3> An adhesive layer was obtained in the same manner as in Preparation Example 1, except that the thickness T1 was changed to 10 μm. 【0065】 <Preparation Example 4> An adhesive layer was obtained in the same manner as in Preparation Example 1, except that the thickness T1 was changed to 50 μm. 【0066】 <Preparation Example 5> An adhesive layer was obtained in the same manner as in Preparation Example 1, except that the thickness T1 was changed to 3 μm. 【0067】 <Preparation Example 6> Except for adding 92.9 parts by mass of butyl acrylate, 7 parts by mass of acrylic acid, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 0.3 parts by mass of dibenzoyl peroxide to 100 parts by mass of the total monomers (solids) together with ethyl acetate, and reacting under a nitrogen gas stream at 60°C for 7 hours, ethyl acetate was added to the reaction solution to obtain a solution containing an acrylic polymer (B) with a weight-average molecular weight of 2,000,000 and a dispersion ratio of 3.9 (solids concentration 30% by mass), the process was the same as in Preparation Example 1, and the elastic modulus was 8.86 × 10⁻⁶. 4 An adhesive layer with a density of Pa was obtained. The thickness T1 of the adhesive layer was 10 μm. 【0068】 <Preparation Example 7> Except for adding 89.9 parts by mass of butyl acrylate, 10 parts by mass of acrylic acid, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 0.3 parts by mass of dibenzoyl peroxide to 100 parts by mass of the total monomers (solids) together with ethyl acetate, and reacting under a nitrogen gas stream at 60°C for 4 hours, ethyl acetate was added to the reaction solution to obtain a solution containing an acrylic polymer with a weight-average molecular weight of 1.2 million and a dispersion ratio of 3.9 (solids concentration 30% by mass), the process was the same as in Preparation Example 1, and the elastic modulus was 8.86 × 10⁻⁶. 2 An adhesive layer with a density of Pa was obtained. The thickness T1 of the adhesive layer was 10 μm. 【0069】 <<Preparation of protective film with adhesive layer>> <Preparation Example 8> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 1 onto the surface of a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, product number "Diafoil") used as a protective film. The thickness T2 of the protective film was 38 μm. Table 1 shows the ratio of the thickness T2 of the protective film to the thickness T1 of the adhesive layer (T1 / T2). 【0070】 <Preparation Example 9> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 2 onto the surface of a PET film (manufactured by Mitsubishi Chemical Corporation, product number "Diafoil") used as a protective film. 【0071】 <Preparation Example 10> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 3 onto the surface of a PET film (manufactured by Mitsubishi Chemical Corporation, product number "Diafoil") used as a protective film. The thickness T2 of the protective film was 30 μm. 【0072】 <Preparation Example 11> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 6 onto the surface of a cycloolefin (COP) resin film (manufactured by Zeon Corporation, product number "ZF-14") used as a protective film. The thickness T2 of the protective film was 13 μm. 【0073】 <Preparation Example 12> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 4 onto the surface of a PET film (manufactured by Mitsubishi Chemical Corporation, product number "Diafoil") used as a protective film. 【0074】 <Preparation Example 13> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 5 onto the surface of a COP-type resin film (manufactured by Zeon Corporation, product number "ZF-14") used as a protective film. 【0075】 <Preparation Example 14> A protective film with an adhesive layer was prepared by laminating the adhesive layer obtained in Preparation Example 7 onto the surface of a COP-type resin film (manufactured by Zeon Corporation, product number "ZF-14") used as a protective film. The thickness T2 of the protective film was 25 μm. 【0076】 <<Preparation of product film>> <Preparation Example 15> A resin film made of PC resin was prepared in the same manner as in Manufacturing Example 9 of Japanese Patent Publication No. 2022-150732. The resin film was elongated and had a thickness of 130 μm. Next, the resin film was uniaxially stretched at a stretching temperature of 150°C and a stretching ratio of 2.8 times at a fixed end to prepare a phase difference film as a product film. The phase difference film was elongated. The thickness of the phase difference film was 47 μm. The in-plane phase difference Re(550) of the phase difference film was 140 nm. 【0077】 <Preparation Example 16> A resin film made of COP-type resin (manufactured by Zeon Corporation, product number "ZF16") was uniaxially stretched at a fixed end at a stretching temperature of 170°C and a stretching ratio of 2.8 times to prepare a phase difference film as a product film. The phase difference film was elongated. The thickness of the phase difference film was 40 μm. The in-plane phase difference Re(550) of the phase difference film was 140 nm. 【0078】 <Preparation Example 17> An optical film was prepared as a product film by simultaneously biaxial stretching at fixed ends of an acrylic resin film (manufactured by Kaneka Corporation, product name "HTX-Z") at a stretching temperature of 125°C and a stretching ratio of 4. The optical film was elongated. The thickness of the optical film was 40 μm. The in-plane phase difference Re(550) of the optical film was 0.5 nm. 【0079】 [Examples 1-4, Comparative Examples 1-3] A first laminating roll and a second laminating roll were prepared. The first laminating roll consisted of a roll body made of silicone rubber (Si rubber) and a shaft made of metal. The outer diameter of the roll body was 250 mm. The second laminating roll consisted of a shaft made of iron (Fe) and a plated coating made of chromium. The outer diameter of the second laminating roll was 250 mm. 【0080】 Next, the first and second bonding rolls were positioned opposite each other so that they were in radial contact with each other. Furthermore, both ends of the second bonding roll were pressed toward the first bonding roll with a cylinder at 10 MPa. Finally, both the first and second bonding rolls were rotated. 【0081】 Next, the adhesive-coated protective film and the product film obtained in the preparation examples shown in Table 1 were supplied between the first and second laminating rolls. The supply speed (line speed) for the adhesive-coated protective film and the product film was 15 m / min. The protective film was in contact with the outer surface of the first laminating roll (roll body), and the product film was in contact with the outer surface (plated coating) of the second laminating roll. 【0082】 The protective film and the product film were pressed against the first and second laminating rolls as they passed between them, and were bonded together by the adhesive layer. As a result, a laminated film having the configuration of a protective film / adhesive layer / product film (phase difference film) was obtained. 【0083】 [Comparative Example 4] A laminated film was obtained in the same manner as in Example 1, except that the adhesive-coated protective film of Preparation Example 8 was changed to the adhesive-coated protective film of Preparation Example 10, the product film of Preparation Example 16 was changed to the product film of Preparation Example 15, and the first and second laminating rolls were swapped so that the laminating roll with a shaft made of Fe was in contact with the protective film, and the laminating roll with a roller body made of Si rubber was in contact with the product film. 【0084】 [Table 1] 【0085】 [evaluation] As is clear from Table 1, the storage modulus of the adhesive layer is 1.0 × 10⁻⁶. 3 Pa~9.9×10 5 It can be seen that a product film with excellent appearance can be achieved when the hardness is Pa, the thickness T1 of the adhesive layer is 5 μm or more, the ratio of the thickness T1 of the adhesive layer to the thickness T2 of the protective film is 1.0 or less, and the ratio of the hardness R2 of the second laminating roll to the hardness R1 of the first laminating roll exceeds 1.0. [Industrial applicability] 【0086】 The method for manufacturing laminated films of the present invention is used to manufacture product films that can be used in various industrial products, and is particularly suitable for the manufacture of optical films (specifically, phase difference films). [Explanation of symbols] 【0087】 1. Protective film 2 Product Film 3a First bonding roll 3b Second bonding roll 5. Adhesive layer 100-layer film

Claims

[Claim 1] The process includes a bonding step in which a protective film and a product film are bonded together by passing them between a first bonding roll and a second bonding roll using an adhesive layer. In the lamination process, the first lamination roll is positioned on the side of the protective film away from the product film, and the second lamination roll is positioned on the side of the protective film away from the product film. The storage modulus of the adhesive layer at 25°C and 55% relative humidity is 1.0 × 10⁻⁶ ３ Pa ~ 9.9 × 10 ５ Pa is, The thickness T1 of the adhesive layer is 5 μm or more, and is 0.10 to 1.0 relative to the thickness T2 of the protective film. A method for manufacturing a laminated film, wherein at 25°C, the hardness R2 of the second laminating roll is 1.01 or more and 2.0 or less relative to the hardness R1 of the first laminating roll.

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