Laminated film, method for manufacturing laminated film, and method for manufacturing optical laminate

Abstract

The present application provides a laminated film capable of inhibiting generation of a minute defect in an image display device, a method for manufacturing the laminated film capable of smoothly manufacturing the laminated film, and a method for manufacturing an optical laminate including the laminated film. The laminated film of the embodiment of the present application successively has a substrate layer, an orientation fixing layer of a liquid crystal compound, an adhesive layer, and a release liner. The release liner is attached to a surface in a thickness direction of the adhesive layer. The release liner is capable of being peeled from the adhesive layer.

Description

Technical Field

[0001] This invention relates to laminated thin films, methods for manufacturing laminated thin films, and methods for manufacturing optical laminates. Background Technology

[0002] Image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays and inorganic EL displays), are rapidly gaining popularity. Image display devices sometimes use laminated optical films containing an alignment fixing layer of a liquid crystal compound. For example, research is underway to fabricate laminated optical films in which an alignment fixing layer of a liquid crystal compound is laminated onto other optical films using an adhesive layer.

[0003] As a method for manufacturing such a stacked optical thin film, for example, the following method has been proposed: after forming an adhesive layer on the surface of a release liner, the surface of the adhesive layer opposite to the release liner is attached to the optical thin film, then the release liner is peeled off from the adhesive layer, and an alignment fixing layer of a liquid crystal compound is attached to the surface of the adhesive layer where the release liner has been peeled off (for example, see Patent Document 1).

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2023-096468 Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] When a stacked optical thin film manufactured using the method described in Patent Document 1 is applied to an image display device, minute defects such as point-like interference inhomogeneities (hereinafter sometimes referred to as point-like inhomogeneities) may sometimes occur.

[0007] The main objective of this invention is to provide a laminated thin film capable of suppressing the generation of minute defects in an image display device, a method for manufacturing the laminated thin film capable of smoothly manufacturing the laminated thin film, and a method for manufacturing an optical laminate containing the laminated thin film.

[0008] means for solving problems

[0009] [1] The laminated film of the present invention comprises, in sequence, a substrate layer, an alignment fixing layer of liquid crystal compound, an adhesive layer and a release liner.

[0010] The release liner is attached to the surface of the adhesive layer in the thickness direction.

[0011] The release liner can be peeled off from the adhesive layer.

[0012] [2] In the laminated film described in [1] above, the orientation fixing layer of the liquid crystal compound can be disposed on the surface of the substrate layer in the thickness direction.

[0013] The substrate layer can be peeled off from the alignment fixing layer of the liquid crystal compound.

[0014] [3] In the laminated film described in [1] or [2] above, the size of the alignment fixing layer of the liquid crystal compound in the orthogonal direction orthogonal to the thickness direction can be greater than or equal to the size of the adhesive layer in the orthogonal direction.

[0015] [4] The laminated film described in any one of [1] to [3] above may be elongated.

[0016] [5] In any of the above-mentioned [1] to [4] stacked films, the orientation fixing layer of the liquid crystal compound may have an in-plane phase difference.

[0017] [6] In any of the laminated films described in any one of [1] to [5] above, the adhesive layer may contain a (meth)acrylic adhesive.

[0018] [7] In any of the above-mentioned [1] to [6] laminated films, the substrate layer may be the coating substrate of the alignment fixing layer of the liquid crystal compound.

[0019] [8] Another aspect of the present invention includes a method for manufacturing a laminated film, comprising: forming an alignment fixing layer of a liquid crystal compound on a surface in the thickness direction of a substrate layer to prepare a first film; forming an adhesive layer on a surface in the thickness direction of a release liner to prepare a second film; and bonding the first film to the second film by contacting the adhesive layer of the second film with the alignment fixing layer of the liquid crystal compound in the first film.

[0020] [9] In the method for manufacturing the laminated film described in [8] above, the adhesive layer of the second film may have a first side on the peeling pad side and a second side located away from the first side in the thickness direction.

[0021] The arithmetic mean roughness Ra of the second surface of the adhesive layer is less than the arithmetic mean roughness Ra of the first surface of the adhesive layer.

[0022]

[10] The method for manufacturing the laminated film described in [8] or [9] above may further include a step of cutting off the two ends of the laminated film in a direction orthogonal to the lamination direction.

[0023]

[11] Another aspect of the method for manufacturing an optical laminate of the present invention further includes: a step of manufacturing the laminated film by the method for manufacturing laminated films described in any one of [8] to

[10] above; a step of peeling the release liner provided on the laminated film from the adhesive layer; a step of attaching the optical film to the surface of the adhesive layer from which the release liner has been peeled; and a step of peeling the substrate layer from the alignment fixing layer of the liquid crystal compound.

[0024]

[12] In the manufacturing method of the optical laminate described in

[11] above, the optical laminate may include a polarizer.

[0025] In this case, the refractive index of the polarizer in the transmission axis direction of the orientation fixing layer of the liquid crystal compound can exceed 1.55.

[0026]

[13] In the manufacturing method of the optical laminate described in

[12] above, the optical thin film may include a polarizer.

[0027] In this case, the refractive index of the polarizer in the transmission axis direction of the alignment fixing layer of the liquid crystal compound can exceed 1.60.

[0028] Invention Effects

[0029] According to embodiments of the present invention, a laminated thin film capable of suppressing the generation of minute defects in an image display device, a method for manufacturing the laminated thin film capable of smoothly manufacturing the laminated thin film, and a method for manufacturing an optical laminate containing the laminated thin film can be realized. Attached Figure Description

[0030] Figure 1 This is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram illustrating the first bonding step included in a method for manufacturing a laminated film according to another aspect of the present invention.

[0032] Figure 3 It is used to explain what follows. Figure 1 A schematic diagram illustrating the cutting process of the first bonding step.

[0033] Figure 4 This is a schematic diagram illustrating the first peeling step included in a method for manufacturing an optical laminate according to another aspect of the present invention.

[0034] Figure 5 It is used to explain what follows. Figure 4 A schematic diagram illustrating the first peeling process and the second bonding process.

[0035] Figure 6It is for Figure 5 A schematic diagram illustrating the optical film in the second bonding process.

[0036] Explanation of reference numerals in the attached figures 1. Substrate layer 2 Liquid crystal alignment fixing layer 3 Adhesive layer 3a First page 3b Second page 4. Peel off the liner 5 First Thin Film 6 Second Thin Film 7 Optical Thin Films Detailed Implementation

[0037] The following describes representative embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, in order to make the description clearer, the accompanying drawings sometimes schematically show the width, thickness, shape, etc. of various parts compared to the embodiments, but these are merely examples and are not intended to limit the interpretation of the present invention.

[0038] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows.

[0039] (1) Refractive index (nx, ny, nz) “nx” is the refractive index in the direction where the refractive index is greatest in the plane (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0040] In the elliptic form (x) 2 / a 2 )+(y 2 / b 2 In equation ()=1, let a be nx, b be ny, and x and y be the refractive indices in the x and y directions along the angle θ on the ellipse. Solve the simultaneous equations using y=x(tanθ) and the aforementioned nx and ny. The refractive index along the transmission axis is obtained by √(x... 2 +y 2 Find the answer.

[0041] The "average refractive index" is obtained by (nx + ny + nz) / 3.

[0042] (2) In-plane phase difference (Re) “Re(λ)” is the in-plane phase difference measured at 23°C with light of wavelength λnm. For example, “Re(550)” is the in-plane phase difference measured at 23°C with light of wavelength 550nm. When the thickness of the layer (thin film) is set to d (nm), Re(λ) is obtained by the formula: Re(λ) = (nx - ny) × d.

[0043] (3) Phase difference in the thickness direction (Rth) “Rth(λ)” is the phase difference in the thickness direction measured at 23°C with light of wavelength λnm. For example, “Rth(550)” is the phase difference in the thickness direction measured at 23°C with light of wavelength 550nm. When the thickness of the layer (thin film) is set to d (nm), Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d.

[0044] (4) Nz coefficient The Nz coefficient is obtained by Nz=Rth / Re.

[0045] (5) Angle When referring to angles in this specification, the angle includes both clockwise and counterclockwise relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0046] (6) In fact, they are parallel or orthogonal The expressions "substantially parallel" and "approximately parallel" include cases where the angle between the two directions is within 0° ± 3°. Conversely, the expressions "substantially orthogonal" and "approximately orthogonal" include cases where the angle between the two directions is 90° ± 3°.

[0047] A. Overview of laminated thin films Figure 1 This is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention.

[0048] like Figure 1 As shown, in one embodiment, the laminated film 100 sequentially comprises a substrate layer 1, a liquid crystal compound alignment fixing layer 2, an adhesive layer 3, and a release liner 4.

[0049] In this specification, "alignment fixing layer of liquid crystal compound" refers to a layer in which the liquid crystal compound is oriented in a specified direction and its orientation state is fixed. It should be noted that "alignment fixing layer," as described below, includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers.

[0050] The adhesive layer 3 has a first surface 3a and a second surface 3b in its thickness direction (hereinafter sometimes simply referred to as the thickness direction). The first surface 3a of the adhesive layer 3 is located on the side of the release liner 4. The second surface 3b of the adhesive layer 3 is located on the side of the first liquid crystal alignment fixing layer 2.

[0051] The release liner 4 is attached to the surface (specifically the first surface 3a) in the thickness direction of the adhesive layer 3. The release liner 4 can be peeled off from the adhesive layer 3.

[0052] The inventors have discovered that minute defects (typically dot-like unevenness) that occur when a laminated film having an alignment fixing layer and an adhesive layer of a liquid crystal compound is applied to an image display device are caused by the surface shape of the adhesive layer.

[0053] Therefore, the inventors conducted an in-depth study on the relationship between minute defects and the surface shape of the adhesive layer. The results showed that when a relatively flat surface in the adhesive layer is positioned closer to the alignment fixing layer of the liquid crystal compound than a relatively rough surface in the adhesive layer, light interference is generated, which can reduce minute defects (typically dot-like unevenness) in the image display device.

[0054] Light interference occurs in thinner layers with stronger interface reflection. That is, light interference is easily generated on the surface of thin layers with high refractive index, such as the alignment fixing layer of a liquid crystal compound. When an adhesive layer is bonded to the rough surface of the alignment fixing layer of a liquid crystal compound, optical path inhomogeneity is generated, resulting in interference inhomogeneity (typically point-like inhomogeneity).

[0055] In one embodiment, a release liner 4 is attached to the first surface 3a of the adhesive layer 3. Therefore, the first surface 3a of the adhesive layer 3 is prone to developing unevenness due to components from the release liner 4 and / or foreign matter adhering to the release liner 4. That is, the first surface 3a of the adhesive layer 3 is relatively rougher than the second surface 3b of the adhesive layer 3. In other words, the second surface 3b of the adhesive layer 3 is relatively flatter than the first surface 3a of the adhesive layer 3.

[0056] In such a laminated film 100, the second side 3b of the adhesive layer 3 is located closer to the alignment fixing layer 2 of the liquid crystal compound than the first side 3a. Therefore, when the laminated film 100 is applied to an image display device, light interference can be reduced, and as a result, the generation of minute defects (typically dot-like unevenness) can be suppressed.

[0057] The laminated film 100 can be in the form of a single sheet or in the form of a strip. In one embodiment, the laminated film 100 is in the form of a strip.

[0058] It should be noted that, in this specification, "elongated" refers to a slender shape whose dimension in the elongated direction is longer than its dimension in the width direction, which is orthogonal to both the elongated and thickness directions. Hereinafter, the dimension in the elongated direction of the film will sometimes be simply referred to as the length, and the dimension in the width direction of the film will sometimes be simply referred to as the width. The length of a film having an elongated shape is, for example, 10 times or more, preferably 20 times or more, relative to its width.

[0059] B. Details of laminated films Next, refer to Figure 1 The laminated film of one embodiment will be described in detail.

[0060] B-1. Substrate layer The substrate layer 1 supports the alignment fixing layer 2 of the liquid crystal compound. The substrate layer 1 has any suitable configuration.

[0061] The substrate layer 1 typically comprises a resin material.

[0062] Examples of resin materials include polyester resins such as polyethylene terephthalate (PET); polyolefin resins such as polyethylene and polypropylene; cyclic olefin (COP) resins such as polynorbornene; cellulose resins such as triacetyl cellulose (TAC); polycarbonate (PC) resins; and (meth)acrylic resins. It should be noted that "(meth)acrylic resins" refers to acrylic resins and / or methacrylic resins.

[0063] Resin materials can be used alone or in combination.

[0064] Among resin materials, polyester resins and cellulose resins are preferred.

[0065] In one embodiment, the substrate layer 1 is a coating substrate for the first liquid crystal alignment fixing layer 2. An alignment treatment is performed on one side of the substrate layer 1 in the thickness direction. The alignment-treated surface of the substrate layer 1 is configured to align the liquid crystal compound, which will be described later.

[0066] Examples of orientation treatments include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment.

[0067] The thickness of the substrate layer 1 is, for example, 5 μm to 100 μm, preferably 20 μm to 80 μm.

[0068] The width of the substrate layer 1 is, for example, 500mm to 2000mm, preferably 1000mm to 1500mm.

[0069] B-2. Alignment fixing layer of liquid crystal compound In one embodiment, the alignment fixing layer 2 of the liquid crystal compound is disposed on the surface of the substrate layer 1 in the thickness direction. In the example shown, the alignment fixing layer 2 of the liquid crystal compound is disposed on the alignment treatment surface of the substrate layer 1.

[0070] The aforementioned substrate layer 1 can be peeled off from the alignment fixing layer 2 of the liquid crystal compound (see reference). Figure 5 Therefore, the substrate layer can be removed as needed. Thus, in image display devices, it is possible to suppress the substrate layer from becoming a source of minute defects and to achieve thinner designs.

[0071] Hereinafter, the alignment fixing layer 2 of the liquid crystal compound is sometimes referred to as the first liquid crystal alignment fixing layer 2.

[0072] The first liquid crystal alignment fixing layer 2 can have an in-plane phase difference or a phase difference in the thickness direction. Preferably, the first liquid crystal alignment fixing layer 2 has an in-plane phase difference.

[0073] The refractive index of the first liquid crystal alignment fixing layer 2 is, for example, expressed as nx > ny = nz. It should be noted that "ny = nz" includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Therefore, without impairing the effects of the present invention, sometimes ny > nz or ny > nz can be used. <nz。

[0074] The in-plane phase difference Re(550) of the first liquid crystal alignment fixing layer 2 is, for example, 100nm to 300nm. The Nz coefficient of the first liquid crystal alignment fixing layer 2 is, for example, 0.9 to 1.5, preferably 0.9 to 1.3.

[0075] The first liquid crystal alignment fixing layer 2 can function as a λ / 2 plate, or as a λ / 3 plate, λ / 4 plate, λ / 5 plate, or C-plate. In the example shown, the first liquid crystal alignment fixing layer 2 functions as a λ / 4 plate.

[0076] When the first liquid crystal alignment fixing layer 2 functions as a λ / 4 plate, the in-plane phase difference Re (550) is preferably 100nm~190nm, more preferably 110nm~170nm, and even more preferably 130nm~160nm.

[0077] In the first liquid crystal alignment fixing layer 2, typically, the rod-shaped liquid crystal compounds are aligned in a state of parallel alignment along a predetermined direction.

[0078] Examples of liquid crystal compounds include those in which the liquid crystal phase is a nematic phase (nematic liquid crystals). Examples of such liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. Liquid crystal polymers and liquid crystal monomers can be used individually or in combination.

[0079] The liquid crystal properties of liquid crystal compounds can be expressed by either lyotropic or thermotropic mechanisms.

[0080] When the liquid crystal compound contains liquid crystal monomers, these monomers are preferably polymerizable or crosslinkable monomers. By polymerizing or crosslinking the liquid crystal monomers (i.e., curing), the orientation state of the liquid crystal monomers can be fixed. After aligning the liquid crystal monomers, for example, if the liquid crystal monomers are polymerized or crosslinked with each other, the aforementioned orientation state can be fixed. Here, polymers are formed through polymerization, and three-dimensional network structures are formed through crosslinking, but these are non-liquid crystals. Therefore, the formed first liquid crystal alignment-fixed layer does not undergo, for example, a transformation to a liquid crystal phase, glassy phase, or crystalline phase caused by temperature changes characteristic of liquid crystal compounds. As a result, the first liquid crystal alignment-fixed layer can possess extremely excellent stability unaffected by temperature changes.

[0081] Any suitable liquid crystal monomer can be used. Examples of liquid crystal monomers include polymerizable mesocrystalline compounds described in Japanese Patent Application Publication No. 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445.

[0082] Specific examples of such polymeric mesocrystalline compounds include BASF's LC242, Merck's E7, and Wacker-Chem's LC-Sillicon-CC3767.

[0083] Specific examples of liquid crystal compounds and detailed methods for forming the alignment fixing layer are described in Japanese Patent Application Publication No. 2006-163343. The contents of that publication are incorporated herein by reference.

[0084] The thickness of the first liquid crystal alignment fixing layer 2 can be arbitrarily and appropriately adjusted to obtain the desired in-plane phase difference. The thickness of the first liquid crystal alignment fixing layer 2 is, for example, 5 μm or less, preferably 3 μm or less, and more preferably 2 μm or less. On the other hand, the lower limit of the thickness of the first liquid crystal alignment fixing layer 2 is typically 0.5 μm.

[0085] In one embodiment, the size of the first liquid crystal alignment fixing layer 2 in an orthogonal direction (hereinafter, sometimes simply referred to as the orthogonal direction) orthogonal to the thickness direction is greater than or equal to the size of the adhesive layer 3 in the orthogonal direction. In particular, the width of the first liquid crystal alignment fixing layer 2 is greater than or equal to the width of the adhesive layer 3. With this configuration, it is possible to increase the size of optical laminates (refer to...) manufactured using laminated thin films. Figure 5 The dimensions (especially the width) of the object.

[0086] The size (typically the width) of the alignment fixing layer 2 of the liquid crystal compound in the orthogonal direction is, for example, 1.000 times to 1.050 times, preferably 1.005 times to 1.030 times, relative to the size (typically the width) of the adhesive layer 3 in the orthogonal direction.

[0087] The width range of the first liquid crystal alignment fixing layer 2 is, for example, the same as the width range of the substrate layer 1 described above.

[0088] The average refractive index of the liquid crystal alignment fixing layer 2 at a wavelength of 550 nm is, for example, 1.45 to 1.65, preferably 1.50 to 1.65, and more preferably 1.55 to 1.65.

[0089] B-3. ​​Adhesive layer In one embodiment, the adhesive layer 3 is disposed on the surface of the first liquid crystal alignment fixing layer 2 opposite to the substrate layer 1.

[0090] Adhesive layer 3 typically contains adhesive.

[0091] Examples of adhesives include (meth)acrylic adhesives, urethane adhesives, and silicone adhesives. Adhesives can be used alone or in combination.

[0092] Among adhesives, (meth)acrylic adhesives are preferred.

[0093] (Meth)acrylic adhesives contain polymers with alkyl (meth)acrylate as the main monomer component (hereinafter referred to as (meth)acrylic polymers). In other words, (meth)acrylic polymers contain structural units derived from alkyl (meth)acrylate. The proportion of structural units derived from alkyl (meth)acrylate in the (meth)acrylic polymer is typically 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, for example 100% by mass or less, and preferably 98% by mass or less.

[0094] The alkyl group in (meth)acrylates can be straight-chain or branched. The alkyl group has, for example, 1 or more but less than 18 carbon atoms. Examples of alkyl groups include methyl, ethyl, butyl, 2-ethylhexyl, decyl, isodecyl, and octadecyl. Alkyl (meth)acrylates can be used alone or in combination. The average number of carbon atoms in the alkyl group is preferably 3 to 10.

[0095] In addition to structural units derived from alkyl methacrylates, (meth)acrylic polymers may also contain structural units derived from comonomers capable of polymerizing with alkyl methacrylates. Examples of comonomers include carboxyl-containing monomers, hydroxyl-containing monomers, amino-containing monomers, and amide-containing monomers. Comonomers can be used alone or in combination.

[0096] In one embodiment, the (meth)acrylic polymer contains, in addition to structural units derived from alkyl (meth)acrylic esters, structural units derived from carboxyl-containing monomers, structural units derived from hydroxyl-containing monomers, and structural units derived from amide-containing monomers.

[0097] Carboxyl-containing monomers are compounds whose structures contain a carboxyl group and polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Examples of carboxyl-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylic acid, maleic acid, fumaric acid, and crotonic acid, with (meth)acrylic acid being the most preferred. When (meth)acrylic acid polymers contain structural units derived from carboxyl-containing monomers, the adhesive properties of the adhesive layer can be improved.

[0098] When the (meth)acrylic polymer contains structural units derived from carboxyl-containing monomers, the proportion of structural units derived from carboxyl-containing monomers is preferably 0.01% by mass or more and 10% by mass or less.

[0099] Hydroxyl-containing monomers are compounds whose structures contain hydroxyl groups and polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 12-hydroxylaurate (meth)acrylate, and methyl (4-hydroxymethylcyclohexyl)acrylate; more preferably, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are also examples; and more preferably, 2-hydroxyethyl (meth)acrylate is another example. When (meth)acrylate polymers contain structural units derived from hydroxyl-containing monomers, the durability of the adhesive layer can be improved.

[0100] When the (meth)acrylic polymer contains structural units derived from hydroxyl-containing monomers, the proportion of structural units derived from hydroxyl-containing monomers in the (meth)acrylic polymer is preferably 0.01% by mass or more and 10% by mass or less.

[0101] Amide monomers are compounds whose structures contain amide groups and polymerizable unsaturated double bonds such as (meth)acryloyl groups and vinyl groups. Examples of amide-containing monomers include (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropylacrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-hydroxymethyl-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth)acrylamide, mercaptoethyl (meth)acrylamide, and other acrylamide monomers; N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, and other N-acryloyl heterocyclic monomers; and N-vinyl lactam monomers containing N-vinyl groups such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam. N-acryloyl heterocyclic monomers are preferred, and N-(meth)acryloylmorpholine is more preferred. When (meth)acrylic polymers contain structural units derived from amide-containing monomers, the durability of the adhesive layer can be improved.

[0102] When the (meth)acrylic polymer contains structural units derived from amide-containing monomers, the proportion of structural units derived from amide-containing monomers in the (meth)acrylic polymer is preferably 1% by mass or more and 10% by mass or less, more preferably 4% by mass or more and 8% by mass or less.

[0103] The weight-average molecular weight (Mw) of the (meth)acrylic polymer is, for example, 100,000 to 4,000,000, preferably 200,000 to 3,000,000.

[0104] Furthermore, (meth)acrylic adhesives preferably contain a crosslinking agent. Representative examples of crosslinking agents include organic crosslinking agents and multifunctional metal chelates, with organic crosslinking agents being preferred.

[0105] Examples of organic crosslinking agents include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, and imine-based crosslinking agents, with isocyanate-based crosslinking agents being the preferred choice.

[0106] When the adhesive contains a crosslinking agent, the proportion of the crosslinking agent is typically 0.01 parts by weight or more and 15 parts by weight or less per 100 parts by weight of the (meth)acrylic polymer.

[0107] Furthermore, (meth)acrylic adhesives can contain various additives (such as polymerization initiators, solvents, and crosslinking catalysts) in appropriate proportions.

[0108] Such adhesive compositions (meth)acrylic adhesives, urethane adhesives, and silicone adhesives) contain a base polymer (or its constituent monomer components) and, as needed, crosslinking agents and solvents. The adhesive compositions may contain additives such as polymerization catalysts, crosslinking catalysts, silane coupling agents, tackifiers, plasticizers, softeners, deterioration inhibitors, fillers, colorants, UV absorbers, antioxidants, surfactants, and antistatic agents, to a extent that does not impair the properties of the invention.

[0109] The thickness of the adhesive layer 3 is, for example, 3 μm or more, preferably 5 μm or more, and more preferably 20 μm or more. On the other hand, the thickness of the adhesive layer 3 is, for example, 50 μm or less, and more preferably 30 μm or less.

[0110] In one embodiment, the width of the adhesive layer 3 is less than or equal to the width of the first liquid crystal alignment fixing layer 2. In the example shown, the width of the adhesive layer 3 is less than the width of the first liquid crystal alignment fixing layer 2.

[0111] Viewed from the thickness direction, the center of the adhesive layer 3 in the width direction is substantially the same as the center of the first liquid crystal alignment fixing layer 2 in the width direction. The distance between the center of the adhesive layer 3 in the width direction and the center of the first liquid crystal alignment fixing layer 2 in the width direction is, for example, 10 mm or less, preferably 5 mm or less, and more preferably 0 mm.

[0112] The width of the adhesive layer 3 is, for example, 1250 mm to 1350 mm, preferably 950 mm to 1450 mm.

[0113] The average refractive index of the adhesive layer 3 at a wavelength of 550 nm is typically less than the average refractive index of the first liquid crystal alignment fixing layer 2 at a wavelength of 550 nm.

[0114] The absolute value of the difference between the average refractive index of the adhesive layer 3 and the average refractive index of the first liquid crystal alignment fixing layer 2 is, for example, 0.01 to 0.30, or 0.05 to 0.20, or 0.10 to 0.14. Even if the average refractive index difference between the adhesive layer and the liquid crystal alignment fixing layer is within such a range, the relatively flat second surface of the adhesive layer is adjacent to the first liquid crystal alignment fixing layer. Therefore, in an image display device using laminated thin films, light interference can be stably reduced.

[0115] The average refractive index of the adhesive layer 3 at a wavelength of 550 nm is, for example, 1.30 to 1.70, preferably 1.42 to 1.52.

[0116] B-4. Stripping the liner The release liner 4 is disposed on the side opposite to the first liquid crystal alignment fixing layer 2 relative to the adhesive layer 3. The release liner 4 is typically temporarily adhered to the first surface 3a of the adhesive layer 3 before the use of the laminated film 100.

[0117] The release liner 4 comprises any suitable resin material. Examples of resin materials include the resin material contained in the substrate layer 1, and preferred examples include polyethylene terephthalate (PET), polyethylene, and polypropylene.

[0118] Resin materials can be used alone or in combination.

[0119] In one embodiment, a release treatment layer is provided on the contact surface of the release liner 4 with the adhesive layer 3.

[0120] The release layer typically contains a release agent.

[0121] Examples of release agents include silicone-based release agents, fluorinated release agents, and long-chain alkyl acrylate release agents. Silicone-based release agents are preferred, and addition-type silicones containing vinyl groups are even more preferred.

[0122] Release agents can be used alone or in combination.

[0123] The thickness of the release layer is, for example, 50nm~400nm.

[0124] The arithmetic mean roughness (Ra) of the contact surface between the release liner 4 and the adhesive layer 3 is, for example, 5 nm to 40 nm, preferably 5 nm to 20 nm. It should be noted that the arithmetic mean roughness (Ra) is measured, for example, according to JIS B0681-2:2018.

[0125] The thickness of the release liner 4 is, for example, 5 μm or more, preferably 20 μm or more. On the other hand, the thickness of the release liner 4 is, for example, 85 μm or less, preferably 45 μm or less. It should be noted that when a release layer is implemented, the thickness of the release liner includes the thickness of the release layer.

[0126] C. Manufacturing method of laminated thin films Next, refer to Figure 2 and Figure 3 A method for manufacturing a laminated film according to one embodiment will be described.

[0127] In one embodiment, the method for manufacturing a laminated film includes a first preparation step, a second preparation step, and a first lamination step. According to this method, compared to conventional methods for manufacturing laminated films, it is possible to reduce processing time and smoothly manufacture laminated films.

[0128] C-1. First Preparation Step like Figure 2 As shown, in the first preparation step, the first liquid crystal alignment fixing layer 2 is formed on the surface of the substrate layer 1 in the thickness direction.

[0129] In one embodiment, a substrate layer 1 on one side of the substrate layer 1 having undergone the aforementioned alignment treatment is prepared. A coating liquid containing the aforementioned liquid crystal compound is prepared and applied to the alignment-treated surface of the substrate layer 1. This aligns the liquid crystal compound in the direction corresponding to the alignment treatment. Then, the alignment state of the liquid crystal compound is fixed using a method corresponding to the liquid crystal compound.

[0130] Thus, a first liquid crystal alignment fixing layer 2 is formed on the surface of the substrate layer 1, and a first thin film 5 is prepared.

[0131] The first film 5 can be in the form of a single sheet or in the form of a strip. In one embodiment, the first film 5 is in the form of a strip.

[0132] C-2. Second Preparation Step In the second preparation step, the adhesive layer 3 is formed on the surface of the release liner 4 in the thickness direction.

[0133] In one embodiment, a release liner 4 having the aforementioned release treatment layer provided on one side in the thickness direction is prepared. Next, the aforementioned adhesive is applied to the surface of the release treatment layer of the release liner 4 using any suitable method. Then, the coating is dried as needed.

[0134] Thus, an adhesive layer 3 is formed on the surface of the release liner 4, and a second film 6 is prepared.

[0135] The second film 6 can be in the form of a single sheet or in the form of a strip. In one embodiment, the second film 6 is in the form of a strip. In the example shown, the first film 5 and the second film 6 are both in the form of strips.

[0136] The adhesive layer 3 of the second film 6 has a first surface 3a on the side of the peeling liner 4 and a second surface 3b located away from the first surface 3a in the thickness direction. In the second film 6, the second surface 3b of the adhesive layer 3 is an air surface and is exposed.

[0137] In one embodiment of the second film 6, the arithmetic mean roughness Ra of the second surface 3b of the adhesive layer 3 is less than the arithmetic mean roughness Ra of the first surface 3a of the adhesive layer 3.

[0138] The arithmetic mean roughness Ra of the second surface 3b of the adhesive layer 3 is, for example, 0.6 times or less, preferably 0.4 times or less, and more preferably 0.2 times or less, relative to the arithmetic mean roughness Ra of the first surface 3a of the adhesive layer 3. On the other hand, the arithmetic mean roughness Ra of the second surface 3b of the adhesive layer 3 is, for example, more than 0.01 times, and also, for example, more than 0.5 times, relative to the arithmetic mean roughness Ra of the first surface 3a of the adhesive layer 3.

[0139] The arithmetic mean roughness Ra of the first surface 3a of the adhesive layer 3 is, for example, 0 μm, and also, for example, 0.02 μm or more, and also, for example, 0.04 μm or more. On the other hand, the arithmetic mean roughness Ra of the first surface 3a of the adhesive layer 3 is, for example, 0.10 μm or less, preferably 0.08 μm or less, and more preferably 0.06 μm or less.

[0140] The arithmetic mean roughness Ra of the second surface 3b of the adhesive layer 3 is, for example, less than 0.06 μm, preferably less than 0.04 μm, and more preferably less than 0.02 μm. On the other hand, the lower limit of the arithmetic mean roughness Ra of the second surface 3b of the adhesive layer 3 is typically 0 μm.

[0141] When the arithmetic mean roughness of the second surface of the adhesive layer in the second film is within such a range, it is possible to improve the smoothness of the second surface of the adhesive layer in the manufactured laminated film. As a result, it is possible to more stably reduce minute defects (typically dot-like unevenness) in image display devices using laminated films.

[0142] C-3. First bonding process like Figure 3 As shown, in the first bonding process, the first film 5 and the second film 6 are bonded together. In one embodiment, the first film 5, which has an elongated shape, and the second film 6, which has an elongated shape, are bonded in such a way that their elongated directions are substantially parallel and their width directions are substantially aligned when viewed from the thickness direction.

[0143] More specifically, the adhesive layer 3 of the second thin film 6 is brought into contact with the first liquid crystal alignment fixing layer 2 of the first thin film 5. Thus, the second surface 3b of the adhesive layer 3 is adjacent to the first liquid crystal alignment fixing layer 2.

[0144] Through the above, a laminated film 100 is manufactured having a substrate layer 1, a first liquid crystal alignment fixing layer 2, an adhesive layer 3, and a release liner 4 in sequence.

[0145] C-4. Cutting process The manufacturing method of laminated films may also include a cutting process, depending on the requirements.

[0146] In the cutting process, the two ends of the laminated film 100 in the direction orthogonal to the lamination direction are cut from the laminated film 100 by any suitable method. In one embodiment, the laminated film 100 is transported along the strip direction while the two ends of the laminated film 100 in the width direction are continuously cut along the strip direction.

[0147] Therefore, the dimensions (especially the width) of the laminated film can be adjusted appropriately. By including a cutting process, the substrate layer 1 can be easily peeled off from the laminated film 100.

[0148] like Figure 4 As shown, in the laminated film 100 after the cutting process, the widths of the substrate layer 1, the first liquid crystal alignment fixing layer 2, the adhesive layer 3, and the release liner 4 are substantially the same.

[0149] D. Manufacturing method of optical laminates Such a laminated film 100 is typically used in an optical laminate 101 that can be applied to an image display device.

[0150] Next, refer to Figure 4 and Figure 5 A method for manufacturing an optical laminate according to one embodiment will be described.

[0151] In one embodiment, the method for manufacturing an optical laminate includes a first peeling step, a second bonding step, and a second peeling step.

[0152] D-1. First stripping process In the method for manufacturing an optical laminate, firstly, a laminated thin film 100 is manufactured by the above-described method for manufacturing laminated thin films.

[0153] Then, as Figure 4 As shown, in the first peeling process, the release liner 4 of the laminated film 100 is peeled off from the adhesive layer 3. As a result, the first surface 3a of the adhesive layer 3 is exposed.

[0154] D-2. Second bonding process Next, as Figure 5 As shown, in the second bonding process, an optical film 7 is attached to the first side 3a of the adhesive layer 3 that has been peeled off from the release liner 4.

[0155] D-2-1. Optical Thin Film The optical thin film 7 can be in the form of a single sheet or in the form of a strip. In one embodiment, the optical thin film 7 is in the form of a strip.

[0156] In one embodiment, the width of the optical film 7 is greater than or equal to the width of the adhesive layer 3.

[0157] The width of the optical film 7 is, for example, 1.000 to 1.030 times, preferably 1.005 to 1.010 times, of the width of the adhesive layer 3. When the width of the optical film is in such a range relative to the width of the adhesive layer, an optical laminate with a wider effective width can be manufactured.

[0158] The optical thin film 7 possesses any suitable optical properties. The optical thin film 7 can have a single-layer structure or a multilayer structure.

[0159] Examples of optical thin films 7 include polarizers, phase retardation films, polarizer protective films, phase retardation protection films, image display device protective films, ultraviolet transmission suppression films, and infrared transmission suppression films. Optical thin films 7 may include these individually or in combination of two or more of them.

[0160] like Figure 6 As shown, in one embodiment, the optical thin film 7 includes a polarizer 7a and a phase retardation film 7b.

[0161] Polarizer 7a typically includes polarizer 71.

[0162] As the polarizer 71, any suitable polarizer can be used. For example, the polarizer can be made of a single layer of resin film, or it can be obtained by using a laminate of two or more layers.

[0163] Specific examples of polarizers composed of single-layer resin films include polarizers obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (PVA)-based resin films, partially formalized PVA-based resin films, and partially saponified ethylene-vinyl acetate copolymer-based films using dichroic substances such as iodine and dichroic dyes; and polyene-based oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. From the perspective of superior optical properties, polarizers obtained by dyeing PVA-based resin films with iodine and then uniaxially stretching them are preferred.

[0164] Specific examples of polarizers obtained using laminates include those using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or those using a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by coating a PVA-based resin solution onto a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizer from the PVA-based resin layer. In one embodiment, a polyvinyl alcohol (PVA) resin layer comprising a halide and a polyvinyl alcohol resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may, as needed, further include air stretching of the laminate at a high temperature (e.g., above 95°C) prior to stretching in the aqueous boric acid solution. Furthermore, in one embodiment, it is preferable that the laminate is subjected to a drying shrinkage treatment, which causes it to shrink by more than 2% in the width direction by heating while being transported along the length direction. Typically, the manufacturing method of this embodiment includes sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing assisted stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, resulting in high optical properties. Additionally, by simultaneously improving the orientation of PVA beforehand, problems such as reduced orientation and dissolution of PVA can be prevented when immersed in water during subsequent dyeing and stretching processes, further achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared to when the PVA-based resin layer does not contain halides, orientation disorder of polyvinyl alcohol molecules and reduction of orientation can be suppressed. Therefore, the optical properties of the polarizer obtained by immersing the laminate in a liquid through dyeing and underwater stretching treatments can be improved. Furthermore, the drying shrinkage treatment shrinks the laminate in the width direction, thereby improving optical properties. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate, and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface for use. Detailed methods for manufacturing such polarizers are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0165] The aforementioned dyeing using iodine is performed, for example, by immersing a PVA-based resin film in an aqueous iodine solution. The stretching ratio for the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. Depending on the needs, the PVA-based resin film may undergo swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. For example, by immersing the PVA-based resin film in water for washing before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based resin film be removed, but the PVA-based resin film can also swell to suppress uneven dyeing.

[0166] The thickness of the polarizer 71 is, for example, 1μm to 80μm, preferably 1μm to 15μm, more preferably 1μm to 12μm, and even more preferably 3μm to 8μm.

[0167] The polarizer 71 typically exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The transmittance of the polarizer 71 is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer 71 is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0168] In addition to the polarizer 71, the polarizer 7a may also include a protective layer 72. The protective layer 72 is disposed on at least one side of the polarizer 71. That is, the protective layer 72 may be disposed on only one side of the polarizer 71, or it may be disposed on both sides of the polarizer 71. In the example shown, the protective layer 72 is disposed on only one side of the polarizer 71. The protective layer 72 is typically attached to the polarizer 71 by means of any suitable adhesive layer (not shown).

[0169] The protective layer is formed from any suitable thin film that can be used as a protective layer for a polarizer. Representative materials that constitute the main component of this film include transparent resins, specifically cyclic olefin (COP) resins such as polynorbornene; polyester resins such as polyethylene terephthalate (PET); cellulose resins such as triacetyl cellulose (TAC); polycarbonate (PC) resins; (meth)acrylic acid resins; polyvinyl alcohol resins; polyamide resins; polyimide resins; polyethersulfone resins; polysulfone resins; polystyrene resins; polyolefin resins; and acetate resins. Additionally, thermosetting or UV-curing resins such as (meth)acrylic acid, urethane, (meth)acrylate urethane, epoxy, and silicone resins can also be used. Furthermore, glassy polymers such as siloxane polymers can also be used. Alternatively, polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups on the side chains, and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups on the side chains can be used. Examples include resin compositions having alternating copolymers of isobutylene and N-methylmaleimide and acrylonitrile-styrene copolymers. The polymer film can, for example, be an extruded product of the above-described resin composition. The resin film material can be used alone or in combination.

[0170] The thickness of the protective layer 72 is, for example, 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and even more preferably 5 μm to 150 μm.

[0171] Additionally, a surface treatment layer may be provided on the surface of the protective layer 72 as needed. Examples of surface treatment layers include hard coatings, anti-reflective layers, anti-adhesion layers, and anti-glare treatment layers.

[0172] The thickness of such a polarizer 7a is, for example, 25 μm to 150 μm, preferably 30 μm to 70 μm.

[0173] The phase retardation film 7b can have an in-plane phase retardation or a phase retardation in the thickness direction.

[0174] The phase retardation film 7b preferably has an in-plane phase retardation.

[0175] The refractive index of the phase retardation film 7b shows, for example, a relationship of nx > ny = nz.

[0176] The in-plane phase difference Re(550) of the retardation film 7b is, for example, 100 nm to 300 nm. The Nz coefficient of the retardation film 7b is, for example, 0.9 to 1.5, preferably 0.9 to 1.3.

[0177] The retardation film 7b can function as a λ / 2 plate, or as a λ / 3 plate, λ / 4 plate, λ / 5 plate, or C-plate. In the example shown, the retardation film 7b functions as a λ / 2 plate.

[0178] When the phase retardation film 7b functions as a λ / 2 plate, the in-plane phase difference Re (550) of the phase retardation film 7b is preferably 200nm~300nm, more preferably 230nm~290nm, and even more preferably 250nm~280nm.

[0179] In one embodiment, the first liquid crystal alignment fixing layer 2 functions as a λ / 4 plate, and the retardation film 7b functions as a λ / 2 plate. With this configuration, the wavelength dispersion characteristics of the manufactured optical laminate can approach ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflection properties can be imparted to the optical laminate.

[0180] It should be noted that the phase retardation film 7b can also function as a λ / 4 plate, and the first liquid crystal alignment fixing layer 2 can function as a λ / 2 plate.

[0181] In the optical thin film 7, the angle between the absorption axis direction of the polarizer 71 and the slow axis direction of the phase difference film 7b is, for example, 10° to 20°, preferably 12° to 18°, and more preferably 14° to 16°.

[0182] In one embodiment, the retardation film 7b includes an alignment fixing layer of a liquid crystal compound. Hereinafter, the alignment fixing layer of the liquid crystal compound in the retardation film 7b will sometimes be referred to as the second liquid crystal alignment fixing layer 74.

[0183] The second liquid crystal alignment fixing layer 74 will be described in the same manner as the first liquid crystal alignment fixing layer 2. Therefore, a detailed description of the second liquid crystal alignment fixing layer 74 will be omitted.

[0184] When the optical laminate 101 includes a second liquid crystal alignment fixing layer 74 and a first liquid crystal alignment fixing layer 2, point-like non-uniformity is easily generated at the interface between the liquid crystal alignment fixing layer and the adhesive, where the refractive index difference with the adhesive is greater. When the optical laminate 101 is a polarizer including a polarizer 71, it is easy for point-like non-uniformity to occur at the interface between the liquid crystal alignment fixing layer and the adhesive, where the refractive index difference with the polarizer is greater in the transmission axis direction. Therefore, it is preferable to attach the second surface 3b of the adhesive layer 3, which has a small arithmetic mean roughness Ra, to the liquid crystal alignment fixing layer, which has a greater refractive index difference with the adhesive. It should be noted that, for convenience, the transmission axis direction of the polarizer (the direction orthogonal to the absorption axis direction) is sometimes simply referred to as the transmission axis direction.

[0185] When the optical laminate 101 is a polarizer including the polarizer 71, the refractive index of the first liquid crystal alignment fixing layer 2 in the transmission axis direction is, for example, 1.50 or more, preferably 1.55 or more, more preferably more than 1.55, even more preferably more than 1.60, and particularly preferably 1.61 or more. On the other hand, the upper limit of the refractive index of the first liquid crystal alignment fixing layer 2 in the transmission axis direction is typically 1.70.

[0186] In addition, the refractive index of the second liquid crystal alignment fixing layer in the transmission axis direction is typically smaller than the refractive index of the first liquid crystal alignment fixing layer 2 in the transmission axis direction.

[0187] The refractive index of the second liquid crystal alignment fixing layer 74 in the transmission axis direction is, for example, 1.40 or more, preferably 1.50 or more. On the other hand, the refractive index of the second liquid crystal alignment fixing layer 74 in the transmission axis direction is, for example, 1.60 or less, preferably less than 1.55.

[0188] In the example shown, the optical thin film 7 also includes an adhesive layer 73. The adhesive layer 73 bonds the polarizer 7a to the retardation film 7b. In the example shown, the adhesive layer 73 is located between the polarizer 71 of the polarizer 7a and the second liquid crystal alignment fixing layer 74 of the retardation film 7b.

[0189] The adhesive layer 73 contains any suitable adhesive. Examples of adhesives include thermosetting adhesives, moisture-curing adhesives, and active energy ray-curing adhesives, with active energy ray-curing adhesives being preferred.

[0190] These adhesives can be used alone or in combination.

[0191] The thickness of the adhesive layer 73 is, for example, 1 μm to 10 μm.

[0192] like Figure 5 As shown, in one embodiment, an optical thin film 7 having an elongated shape and a laminated thin film 100 having an elongated shape are bonded together in such a way that their elongated directions are substantially parallel and their width directions are substantially aligned when viewed from the thickness direction.

[0193] More specifically, the phase retardation film 7b that enables the optical thin film 7 (refer to...) Figure 6 The optical film 7 is thus attached to the first surface 3a of the adhesive layer 3.

[0194] Through the above, an optical laminate 101 is manufactured having a substrate layer 1, a first liquid crystal alignment fixing layer 2, an adhesive layer 3, and an optical thin film 7 in sequence.

[0195] Then, as needed, the substrate layer 1 is peeled off from the first liquid crystal alignment fixing layer 2 (second peeling process).

[0196] When the optical thin film 7 is equipped with a polarizer 71 and a second liquid crystal alignment fixing layer 74 (see reference) Figure 6 In the optical laminate 101, the angle between the absorption axis direction of the polarizer 71 and the slow axis direction of the first liquid crystal alignment fixing layer 2 is, for example, 70°~80°, preferably 72°~78°, and more preferably 74°~76°.

[0197] With this configuration, the wavelength dispersion characteristics of the optical laminate containing the first liquid crystal alignment fixing layer and the second liquid crystal alignment fixing layer can be made closer to the ideal inverse wavelength dispersion characteristics. Therefore, excellent anti-reflection properties can be stably imparted to the optical laminate.

[0198] It should be noted that the range of the angle between the absorption axis direction of the polarizer and the slow axis direction of the first liquid crystal alignment fixing layer and the range of the angle between the absorption axis direction of the polarizer and the slow axis direction of the second liquid crystal alignment fixing layer can be opposite.

[0199] The aforementioned laminated thin film and optical laminate can each be applied to any suitable image display device. Examples of image display devices include liquid crystal displays and organic EL displays. Typically, an image display device includes an image display panel comprising image display units and the aforementioned optical laminate.

[0200] In one embodiment, the optical laminate is applied to the image display device to impart anti-reflective properties. That is, the optical laminate is suitable for use as an anti-reflective optical laminate. Additionally, the optical laminate including a polarizer can be suitably applied as a polarizer in an organic EL display device for OLEDs.

[0201] Example

[0202] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. It should be noted that the methods for measuring each characteristic are as follows.

[0203] (1) Arithmetic mean roughness Ra of the adhesive layer surface Using a white interferometer (Zygo NewView9000), the surface of the adhesive layer in the examples and comparative examples was measured under the following conditions to obtain two-dimensional images. The two-dimensional images were then analyzed to calculate the arithmetic mean roughness Ra of the adhesive layer surface.

[0204] Measurement conditions for white light interferometer: Objective lenses: ×10 Internal lens: ×1.0 Resolution: 1.09μm Measured field area (S): 0.3641 mm 2 Removed: Cylinder [Example 1] <<First Preparation Step>> A liquid crystal composition (coating solution) is prepared by dissolving 10 parts by mass of a polymerizable liquid crystal (manufactured by BASF: trade name "Paliocolor LC242", denoted by the following formula) that will display a nematic liquid crystal phase, and 3 parts by mass of a photopolymerization initiator (manufactured by BASF: trade name "Irgacure 907") relative to the polymerizable liquid crystal compound in 40 parts by mass of toluene.

[0205] [Chemical Formula 1]

[0206] An alignment treatment was performed by rubbing the surface of a strip-shaped polyethylene terephthalate (PET) film (substrate layer, 38 μm thick) with a rubbing cloth. The orientation treatment direction was set to 75° relative to the absorption axis of the polarizer when viewed from the visual recognition side when the film was attached to the optical film (described later).

[0207] The liquid crystal coating liquid was applied to the oriented surface using a bar coater and then heated and dried at 90°C for 2 minutes, thereby orienting the liquid crystal compound.

[0208] The liquid crystal layer thus formed was irradiated with a metal halide lamp at a concentration of 1 mJ / cm². 2 The light is used to cure the liquid crystal layer, thereby forming a first liquid crystal alignment fixing layer on the PET film. The thickness of the first liquid crystal alignment fixing layer is 1 μm.

[0209] The first liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. The in-plane phase difference Re(550) of the first liquid crystal alignment fixing layer is 140 nm. That is, the first optical thin film can function as a λ / 4 plate. The average refractive index of the first liquid crystal alignment fixing layer is 1.59, and the refractive index of the first liquid crystal alignment fixing layer in the transmission axis direction is 1.65.

[0210] Thus, a first film having a first liquid crystal alignment fixing layer and a PET film (substrate layer) is prepared. The first film has an elongated shape. The width of the first film is 1310 mm.

[0211] <<Second Preparation Process>> A 38 μm thick polyethylene terephthalate (PET) film (Mitsubishi Polyester Film Co., Ltd., MRF38), which is a release film with an organosilicon-treated release surface, was used as the release liner.

[0212] A monomer mixture containing 91 parts by mass of butyl acrylate, 6 parts by mass of acryloylmorpholine, 2.7 parts by mass of acrylic acid, and 0.3 parts by mass of 4-hydroxybutyl acrylate was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, and a cooler. Then, relative to 100 parts by mass of this monomer mixture, 0.1 parts by mass of 2,2'-azobisisobutyronitrile (2,2'-Azobisisobutyronitrile) as a polymerization initiator was added along with 100 parts by mass of ethyl acetate. After nitrogen purging by slowly stirring, the liquid temperature in the flask was maintained at approximately 55°C for 8 hours to prepare an acrylic polymer solution with a weight-average molecular weight (Mw) of 2.7 million.

[0213] Relative to 100 parts by weight of the solids component of the acrylic polymer solution, 0.1 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / toluene diisocyanate adduct: manufactured by Tosoh Corporation, trade name "CORONATE L"), 0.3 parts by weight of a peroxide crosslinking agent (benzoyl peroxide: manufactured by Nippon Yushi Co., Ltd., trade name "NYPER BMT"), and 0.2 parts by weight of an epoxy-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") were mixed to obtain an adhesive composition. The polymer concentration of the adhesive composition was adjusted to 8% by weight.

[0214] Next, an adhesive composition is applied to the silicone-treated surface of the release liner, and then allowed to dry to form an adhesive layer. The thickness of the adhesive layer is 25 μm. The average refractive index of the adhesive layer is 1.47.

[0215] The arithmetic mean roughness Ra of the first surface of the adhesive layer on the release liner side is 0.05 μm. The arithmetic mean roughness Ra of the second surface (air surface) of the adhesive layer opposite to the first surface is 0.01 μm.

[0216] Thus, a second film comprising a release liner and an adhesive layer is prepared. The second film is elongated. The width of the adhesive layer in the second film is 1300 mm.

[0217] <<First Bonding Process>> Next, the first film and the second film are bonded together in such a way that their long strips are substantially parallel and their widths are substantially aligned when viewed from the thickness direction.

[0218] More specifically, the first liquid crystal alignment fixing layer of the first film is brought into contact with the second side of the adhesive layer of the second film, thereby bonding the first film and the second film together.

[0219] Thus, a laminated film is obtained having a substrate layer, a first liquid crystal alignment fixing layer, an adhesive layer and a release liner in sequence.

[0220] <<Cutting Process>> Next, the two ends of the laminated film in the width direction are cut off. The width of the laminated film after cutting is 1290 mm.

[0221] <<First Stripping Process>> Next, the release liner of the laminated film is peeled off from the adhesive layer. As a result, the first side of the adhesive layer is exposed.

[0222] <<Second bonding process>> First, the optical thin film is prepared as follows.

[0223] As a thermoplastic resin substrate, a strip-shaped amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) with a Tg of about 75 °C is used to perform corona treatment on one side of the resin substrate.

[0224] 13 parts by mass of potassium iodide were added to 100 parts by mass of a PVA-based resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1. The resulting product was dissolved in water to prepare a PVA aqueous solution (coating solution).

[0225] The above-mentioned PVA aqueous solution is coated on the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

[0226] The resulting laminate was stretched uniaxially in the longitudinal direction (length direction) to 2.4 times its original size in an oven at 130°C (air-assisted stretching treatment).

[0227] Next, the laminate was immersed in an insoluble bath (an aqueous solution of boric acid prepared by mixing 4 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 40°C for 30 seconds (insoluble treatment).

[0228] Next, the polarizer is immersed in a staining bath (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a weight ratio of 1:7 relative to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the final polarizer's monomer transmittance (Ts) becomes the desired value (staining treatment).

[0229] Next, immerse the sample in a crosslinking bath at 40°C (a boric acid aqueous solution prepared by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) for 30 seconds (crosslinking treatment).

[0230] Then, while immersing the laminate in a boric acid aqueous solution at a liquid temperature of 70°C (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%), it was subjected to uniaxial stretching (water stretching treatment) in the longitudinal direction (length direction) between rollers with different circumferential speeds, with a total stretching ratio of 5.5 times.

[0231] Then, the laminate was immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution of 4 parts by mass of potassium iodide mixed with 100 parts by mass of water) (cleaning treatment).

[0232] Then, while drying in an oven maintained at approximately 90°C, it comes into contact with SUS heated rollers maintained at a surface temperature of approximately 75°C (drying shrinkage treatment).

[0233] In this way, a polarizer with a thickness of about 5 μm is formed on the resin substrate, resulting in a laminate with a resin substrate / polarizer structure.

[0234] A 25 μm thick norbornene resin film was laminated as a protective layer onto the polarizer surface (the side opposite to the resin substrate) of the resulting laminate. Next, the resin substrate was peeled off from the polarizer.

[0235] Thus, a polarizer with a protective layer and a polarizer is prepared. The polarizer is elongated and has a width of 1300 mm.

[0236] In addition, the coating thickness was changed, and the alignment processing direction was changed to a 15° angle relative to the absorption axis of the polarizer when viewed from the visual recognition side. Furthermore, a second liquid crystal alignment fixing layer was formed on the PET film in the same manner as the first preparation step. The thickness of the second liquid crystal alignment fixing layer is 2 μm.

[0237] The second liquid crystal alignment fixing layer has a refractive index of nx > ny = nz. The in-plane phase difference Re(550) of the second liquid crystal alignment fixing layer is 270 nm. That is, the second liquid crystal alignment fixing layer functions as a λ / 2 plate. The average refractive index of the second liquid crystal alignment fixing layer is 1.59, and the refractive index along the transmission axis of the second liquid crystal alignment fixing layer is 1.54.

[0238] Thus, a second retardation film is prepared, comprising a second liquid crystal alignment fixing layer and a PET film (substrate layer) as the second optical film. The second retardation film has an elongated shape and a width of 1300 mm.

[0239] Next, the polarizer and the second phase difference film are bonded together using a UV-curable adhesive, with their longitudinal direction substantially parallel and their width direction substantially aligned when viewed from the thickness direction.

[0240] More specifically, a UV-curable adhesive is coated onto the surface of the polarizer of the polarizer to form a coating film. Next, the second liquid crystal phase alignment fixing layer of the second retardation film is brought into contact with the coating film from the side opposite to the first retardation film. Then, the coating film is irradiated with ultraviolet light to cure the UV-curable adhesive.

[0241] Thus, an optical thin film comprising a polarizer, an adhesive layer, and a phase retardation film is prepared.

[0242] The adhesive layer consists of a cured product of a UV-curable adhesive. The thickness of the adhesive layer is 1 μm. The width of the adhesive layer is 1295 mm.

[0243] In the optical thin film, the angle between the absorption axis of the polarizer and the slow axis of the second liquid crystal phase alignment fixing layer is 15°.

[0244] Next, the laminated film and the optical film are bonded together in such a way that their long strips are substantially parallel and their widths are substantially aligned when viewed from the thickness direction.

[0245] More specifically, firstly, the PET film (substrate layer) of the optical film is peeled off from the second liquid crystal alignment fixing layer. Then, the second liquid crystal alignment fixing layer of the optical film is brought into contact with the first side of the adhesive layer of the laminated film, and the laminated film and the optical film are bonded together.

[0246] Thus, an optical laminate comprising a polarizer, an adhesive layer, a phase retardation film (second liquid crystal alignment fixing layer), an adhesive layer, a first liquid crystal alignment fixing layer, and a substrate layer is prepared.

[0247] In the optical laminate, the angle between the absorption axis of the polarizer and the slow axis of the first liquid crystal alignment fixing layer is 75°.

[0248] Then, the substrate layer is peeled off from the first liquid crystal alignment fixing layer (second peeling process).

[0249] [Comparative Example 1] The width of the adhesive layer is changed to 1290 mm. Otherwise, the second film is prepared in the same manner as the second preparation step described above.

[0250] Next, the second film is bonded to the aforementioned optical film in such a manner that their longitudinal direction is substantially parallel and their width direction is substantially aligned when viewed from the thickness direction.

[0251] More specifically, firstly, the substrate layer of the optical film is peeled off from the second liquid crystal alignment fixing layer. Then, the second liquid crystal alignment fixing layer of the optical film is brought into contact with the second side of the adhesive layer of the second film, and the second film and the optical film are bonded together.

[0252] Thus, a laminate comprising a polarizer, an adhesive layer, a phase difference film (second liquid crystal alignment fixing layer), an adhesive layer, and a release liner is prepared.

[0253] In addition, the first film is prepared in the same manner as the first preparation step described above.

[0254] Then, the prepared laminate is bonded to the first film in such a way that their longitudinal directions are substantially parallel and their width directions are substantially aligned when viewed from the thickness direction.

[0255] More specifically, firstly, the release liner of the laminate is peeled off from the adhesive layer, exposing the first side of the adhesive layer. Then, the first liquid crystal alignment fixing layer of the first film is brought into contact with the first side of the adhesive layer, and the laminate is bonded to the first film.

[0256] Thus, an optical laminate comprising a polarizer, an adhesive layer, a phase retardation film (second liquid crystal alignment fixing layer), an adhesive layer, a first liquid crystal alignment fixing layer, and a first substrate layer is prepared.

[0257] In the optical laminate, the angle between the absorption axis of the polarizer and the slow axis of the first liquid crystal alignment fixing layer is 75°.

[0258] Next, the two ends of the optical laminate in the width direction are cut off. The width of the cut optical laminate is 1280 mm.

[0259] Then, the first substrate layer is peeled off from the first liquid crystal alignment fixing layer (second peeling process).

[0260] [evaluate] An acrylic adhesive was applied to the surface of the first liquid crystal phase alignment fixing layer of the optical laminate obtained in Example 1 and Comparative Example 1. The optical laminate was then bonded to a V3 reflector (manufactured by NEODIS Corporation) using this acrylic adhesive to create a test sample. The length of the test sample was 5 m. The test sample was observed visually under a three-wavelength fluorescent lamp.

[0261] In the optical laminate of Example 1, since the second side of the relatively flat adhesive layer is adjacent to the first liquid crystal alignment fixing layer, no dot-like unevenness is visually discernible.

[0262] On the other hand, in the optical laminate of Comparative Example 1, the first surface of the relatively rough adhesive layer is adjacent to the first liquid crystal alignment fixing layer, so dot-like unevenness can be visually perceived.

[0263] Industrial availability The laminated thin films of the embodiments of the present invention can be used to manufacture optical laminates for use in image display devices (such as liquid crystal display devices and organic EL display devices).

Claims

1. A laminated film comprising, in sequence, a substrate layer, an alignment fixing layer of a liquid crystal compound, an adhesive layer, and a release liner. The release liner is attached to the surface of the adhesive layer in the thickness direction and can be peeled off from the adhesive layer.

2. The laminated film according to claim 1, wherein, The alignment fixing layer of the liquid crystal compound is disposed on the surface of the substrate layer in the thickness direction. The substrate layer can be peeled off from the alignment fixing layer of the liquid crystal compound.

3. The laminated film according to claim 1 or 2, wherein, In an orthogonal direction orthogonal to the thickness direction, the size of the alignment fixing layer of the liquid crystal compound is greater than or equal to the size of the adhesive layer.

4. The laminated film according to claim 1 or 2, wherein it is elongated.

5. The laminated film according to claim 1 or 2, wherein, The alignment fixing layer of the liquid crystal compound has an in-plane phase difference.

6. The laminated film according to claim 1 or 2, wherein, The adhesive layer comprises a (meth)acrylic adhesive.

7. The laminated film according to claim 1 or 2, wherein, The substrate layer is a coated substrate for the alignment fixing layer of the liquid crystal compound.

8. A method for manufacturing a laminated thin film, comprising: A process of forming an alignment fixing layer of liquid crystal compound on the surface of a substrate layer in the thickness direction to prepare a first thin film; The process of forming an adhesive layer on the surface in the thickness direction of the peeling liner to prepare the second film; as well as The process of bonding the first film and the second film by bringing the adhesive layer of the second film into contact with the alignment fixing layer of the liquid crystal compound of the first film.

9. The method for manufacturing a laminated thin film according to claim 8, wherein, The second film has an adhesive layer having a first side on the side of the release liner in the thickness direction and a second side located away from the first side. The arithmetic mean roughness Ra of the second surface of the adhesive layer is less than the arithmetic mean roughness Ra of the first surface of the adhesive layer.

10. The method for manufacturing a laminated film according to claim 8, further comprising a step of cutting off both ends of the laminated film in a direction orthogonal to the lamination direction.

11. A method for manufacturing an optical laminate, wherein, Also includes: The process of manufacturing the laminated film by the method of manufacturing the laminated film according to any one of claims 8 to 10; The process of peeling the release liner of the laminated film from the adhesive layer; The process of attaching an optical film to the surface of the adhesive layer after the release liner has been peeled off; as well as The process of peeling the substrate layer from the alignment fixing layer of the liquid crystal compound.

12. The method for manufacturing an optical laminate according to claim 11, wherein, The optical laminate includes a polarizer, and the refractive index of the polarizer in the transmission axis direction of the orientation fixing layer of the liquid crystal compound exceeds 1.

55.

13. The method for manufacturing an optical laminate according to claim 12, wherein, The optical thin film includes a polarizer, and the refractive index of the polarizer in the transmission axis direction of the alignment fixing layer of the liquid crystal compound exceeds 1.60.

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