Multilayer stretch film and method of making same

Abstract

The present application provides a kind of multilayer stretch film, it includes stretch layer (L2) and at least one stretch layer (L1), above-mentioned stretch layer (L1) is arranged in the outermost side of above-mentioned multilayer stretch film and includes thermoplastic resin (P1), above-mentioned thermoplastic resin (P1) includes microparticle, above-mentioned stretch layer (L2) includes thermoplastic resin (P2), above-mentioned thermoplastic resin (P2) includes containing alicyclic structure polymer, above-mentioned thermoplastic resin (P1) and thermoplastic resin (P2) satisfy formula (1): Tg2-Tg1>0 ℃, here, Tg1 indicates the glass transition temperature of above-mentioned thermoplastic resin (P1), Tg2 indicates the glass transition temperature of above-mentioned thermoplastic resin (P2).

Description

Technical Field

[0001] This invention relates to a multilayer stretch film and its manufacturing method. Background Technology

[0002] Thermoplastic resins with excellent transparency are preferred materials for manufacturing optical films. Furthermore, experiments have been conducted to produce multilayer films with properties different from those of single-layer films.

[0003] Patent Document 1 discloses a multilayer stretched film having a polycarbonate layer, which can be used as an optical film such as a polarizer protective film. Patent Document 2 discloses a multilayer retardation film having a layer containing microparticles and a layer containing an ultraviolet absorber.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-274505;

[0007] Patent Document 2: Japanese Patent No. 5845702. Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Layers of thermoplastic resins containing alicyclic polymers sometimes lack sufficient lubricity. When lubricity is insufficient, defects such as scratches may occur in the thermoplastic resin layer due to adhesion, and the optical properties of the layer may deteriorate.

[0010] However, when the resin constituting the layer contains microparticles to improve lubrication, sometimes the microparticles are exposed on the surface of the layer during stretching, causing them to detach from the layer and reducing its optical properties.

[0011] Therefore, there is a need for a multilayer stretched film that reduces the exposure of microparticles on the surface of the outermost layer; and a method for manufacturing the multilayer stretched film.

[0012] Solution for solving the problem

[0013] The inventors conducted in-depth research and found that by producing a multilayer stretched film containing thermoplastic resins (P1) and (P2) with a specified relationship in their glass transition temperatures, the above-mentioned problems could be solved, thus completing the present invention.

[0014] That is, the present invention provides the following solution.

[0015] [1] A multilayer stretch film comprising a stretch layer (L2) and at least one stretch layer (L1), wherein the stretch layer (L1) is disposed on the outermost side of the multilayer stretch film and comprises a thermoplastic resin (P1), wherein the thermoplastic resin (P1) comprises microparticles, wherein the stretch layer (L2) comprises a thermoplastic resin (P2), wherein the thermoplastic resin (P2) comprises a polymer containing an alicyclic structure, wherein the thermoplastic resin (P1) and the thermoplastic resin (P2) satisfy the following formula (1): Tg2-Tg1>0℃ (1), wherein Tg1 represents the glass transition temperature of the thermoplastic resin (P1) and Tg2 represents the glass transition temperature of the thermoplastic resin (P2).

[0016] [2] According to the multilayer stretch film of [1], wherein the thermoplastic resin (P1) and the thermoplastic resin (P2) satisfy the following formula (2): Tg2-Tg1>15℃ (2).

[0017] [3] The multilayer stretch film according to [1] or [2], wherein the stretch layer (L1) and the main surface of the stretch layer (L2) are in contact.

[0018] [4] The multilayer stretch film according to any one of [1] to [3], wherein the multilayer stretch film comprises two stretch layers (L1).

[0019] [5] The multilayer stretch film according to any one of [1] to [4], wherein the thickness of the stretch layer (L1) is smaller than the thickness of the stretch layer (L2).

[0020] [6] The multilayer stretch film according to any one of [1] to [5], wherein the microparticles contained in the thermoplastic resin (P1) are silica microparticles or cross-linked polymer microparticles.

[0021] [7] The multilayer stretch film according to any one of [1] to [6], wherein the birefringence Δn of the multilayer stretch film is 0.002 or more.

[0022] [8] A method for manufacturing a multilayer stretch film, which is the method for manufacturing a multilayer stretch film according to any one of [1] to [7], includes the following steps: step (1), obtaining a laminate, the laminate comprising a resin layer (L2′) and at least one resin layer (L1′), the resin layer (L1′) comprising the thermoplastic resin (P1), the resin layer (L2′) comprising the thermoplastic resin (P2), the resin layer (L1′) being disposed on the outermost side of the laminate; and step (2), stretching the laminate.

[0023] [9] According to the method for manufacturing a multilayer stretch film as described in [8], the above-mentioned step (1) includes a step of co-extruding the above-mentioned resin layer (L1′) and the above-mentioned resin layer (L2′).

[0024]

[10] The method for manufacturing a multilayer stretch film according to [8] includes a step of coating the main surface of the resin layer (L2′) with a composition comprising the thermoplastic resin (P1).

[0025]

[11] According to the method for manufacturing a multilayer stretch film as described in [8], the above-mentioned step (1) includes the step of extruding the above-mentioned thermoplastic resin (P1) on the main surface of the above-mentioned resin layer (L2′).

[0026]

[12] According to the manufacturing method of the multilayer stretch film described in [8], the above-mentioned step (1) includes the step of bonding the above-mentioned resin layer (L1′) and the above-mentioned resin layer (L2′).

[0027] Invention Effects

[0028] According to the present invention, a multilayer stretched film that reduces the exposure of microparticles on the surface of the outermost layer can be provided; and a method for manufacturing the multilayer stretched film can be provided. Attached Figure Description

[0029] Figure 1 A cross-sectional view of the multilayer stretched film of Embodiment 1 is shown schematically.

[0030] Figure 2 A cross-sectional view of the multilayer stretched film of Embodiment 2 is shown schematically. Detailed Implementation

[0031] The present invention will now be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented in any way without departing from the scope of the claims and their equivalents. The constituent elements of the embodiments shown below can be appropriately combined. Furthermore, in the drawings, the same reference numerals are used to denote the same constituent elements, and their descriptions are sometimes omitted.

[0032] In the following description, "long strip" film refers to a film with a length of 5 times or more relative to its width, preferably 10 times or more, specifically meaning a length sufficient to be rolled up for storage or transport. There is no particular upper limit to the length of the film; for example, it can be less than 100,000 times its width.

[0033] In the following description, the term "(meth)acrylic acid" includes "acrylic acid", "methacrylic acid", and combinations thereof.

[0034] In the following description, unless otherwise specified, the in-plane phase difference Re of the layer is represented by Re = (nx - ny) × d. Furthermore, unless otherwise specified, the phase difference Rth in the thickness direction of the film is represented by Rth = {(nx + ny) / 2} - nz} × d. Here, nx represents the refractive index in the direction perpendicular to the thickness direction of the layer (in-plane direction). ny represents the refractive index in the direction orthogonal to the nx direction in the aforementioned in-plane direction of the layer. nz represents the refractive index in the thickness direction of the layer. d represents the thickness of the layer. Unless otherwise specified, the measurement wavelength is 590 nm.

[0035] In the following description, unless otherwise stated, the orientation of elements as “parallel,” “perpendicular,” and “orthogonal” may also include errors within, for example, the range of ±3°, ±2°, or ±1°, without impairing the effects of the invention.

[0036] [1. Overview of Multilayer Stretch Film]

[0037] An embodiment of the multilayer stretch film of the present invention includes a stretch layer (L2) and at least one stretch layer (L1), wherein the stretch layer (L1) is disposed on the outermost side of the multilayer stretch film and includes a thermoplastic resin (P1) comprising microparticles, and the stretch layer (L2) includes a thermoplastic resin (P2) comprising a polymer containing an alicyclic structure.

[0038] The above-mentioned thermoplastic resin (P1) and the above-mentioned thermoplastic resin (P2) satisfy the following formula (1):

[0039] Tg2-Tg1>0℃ (1),

[0040] Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2).

[0041] Preferably, the above-mentioned thermoplastic resin (P1) and the above-mentioned thermoplastic resin (P2) satisfy the following formula (2):

[0042] Tg2-Tg1>15℃ (2).

[0043] The value of (Tg2-Tg1) is more preferably 20°C or higher, more preferably 25°C or higher, more preferably 30°C or higher, preferably 100°C or lower, more preferably 70°C or lower, and more preferably 50°C or lower.

[0044] By using a multilayer stretched film with the above structure, it is possible to reduce the exposure of microparticles on the surface of the stretched layer (L1).

[0045] When particles are exposed on the surface of the stretch layer (L1), they may detach from the multilayer stretch film and reattach to its surface, or the surface roughness of the multilayer stretch film may change, thus reducing the optical performance of the multilayer stretch film. Therefore, it is preferable to reduce the exposure of particles on the surface of the stretch layer (L1).

[0046] The multilayer stretched film of this embodiment is preferably a film obtained by co-stretching a laminate, wherein the laminate has a first layer disposed on the outermost side and containing a thermoplastic resin (P1) and a second layer containing a thermoplastic resin (P2).

[0047] The laminate is typically heated during co-stretching of the thermoplastic resin. The heating temperature is usually set according to the glass transition temperature of the thermoplastic resin contained in the laminate.

[0048] By satisfying equation (1) with thermoplastic resins (P1) and (P2), when the laminate is heated to a certain temperature and stretched, it is expected that the stretchability of thermoplastic resin (P1) will be higher than that of thermoplastic resin (P2). Therefore, even if the stretching temperature of the laminate is set according to the glass transition temperature of thermoplastic resin (P2), the thermoplastic resin (P1) covering the microparticles can be sufficiently stretched on the surface of the stretching layer (L1) without breaking, reducing the exposure of microparticles from the surface.

[0049] Multilayer stretched films can be either strips or sheets. Since multilayer stretched films can be combined with other optical components using a roll-to-roll method, strips are preferred.

[0050] [2. Constituent Elements of Multilayer Stretch Film]

[0051] [2.1. Tension Layer (L1)]

[0052] The stretched layer (L1) is a stretched layer containing thermoplastic resin (P1), formed from thermoplastic resin (P1). The thermoplastic resin (P1) contains microparticles.

[0053] Films formed from thermoplastic resins containing alicyclic polymers sometimes lack sufficient lubricity. By providing a stretching layer (L1) containing a thermoplastic resin (P1) comprising microparticles on the outermost side of the multilayer stretch film, the multilayer stretch film can still exhibit good lubricity even when the stretching layer (L2) described later contains a thermoplastic resin (P2) which in turn contains alicyclic polymers.

[0054] Thermoplastic resins (P1) typically contain thermoplastic polymers. Examples of polymers that can be included in thermoplastic resins (P1) include: alicyclic polymers such as norbornene polymers; polyolefins such as polyethylene and polypropylene; cellulose polymers such as cellulose diacetate and cellulose triacetate; polyesters such as polyethylene terephthalate, polyethylene terephthalate, and polyethylene naphthalate; polycarbonate; (meth)acrylic acid polymers; polyvinyl alcohol; and polymers of styrene or styrene derivatives. These can be used individually or in combination of two or more in any ratio. The polymers that can be included in thermoplastic resins (P1) can be homopolymers or copolymers.

[0055] Due to their excellent heat and moisture resistance, thermoplastic resins (P1) are particularly preferred to contain polymers with alicyclic structures.

[0056] Alicyclic polymers refer to polymers that contain alicyclic structures in their main chain and / or side chains. From the viewpoint of improving the mechanical strength and heat resistance of multilayer stretched films, alicyclic polymers containing alicyclic structures in their main chain are preferred.

[0057] Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkanes) and unsaturated alicyclic hydrocarbon (cycloalkenes, cycloalkynes). From the viewpoint of mechanical strength and heat resistance, cycloalkanes and cycloalkenes are particularly preferred, and cycloalkanes are even more preferred.

[0058] There is no particular limitation on the number of carbon atoms constituting the alicyclic structure, but it is usually 4 or more, preferably 5 or more, usually 30 or less, preferably 20 or less, and more preferably 15 or less. By controlling the number of carbon atoms constituting the alicyclic structure within the above range, the mechanical strength, heat resistance, and formability of the multilayer stretched film are highly balanced, which is preferred.

[0059] The proportion of repeating units containing alicyclic structures in the alicyclic polymer can be appropriately selected according to the intended use of the multilayer stretch film. The proportion of repeating units containing alicyclic structures in 100% by weight of the alicyclic polymer is preferably 55% by weight or more, more preferably 70% by weight or more, even more preferably 90% by weight or more, and typically 100% by weight or less. When the proportion of repeating units containing alicyclic structures in the alicyclic polymer is within the above range, the transparency and heat resistance of the multilayer stretch film can be effectively improved.

[0060] Examples of polymers containing alicyclic structures include norbornene polymers, monocyclic cyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and their hydrides. Among these, norbornene polymers and their hydrides are preferred due to their good transparency and moldability.

[0061] Examples of norbornene-based polymers include: ring-opening polymers of monomers having a norbornene structure and their hydrides; addition polymers of monomers having a norbornene structure and their hydrides. Furthermore, examples of ring-opening polymers of monomers having a norbornene structure include: ring-opening homopolymers of a single monomer having a norbornene structure; ring-opening copolymers of two or more monomers having a norbornene structure; and ring-opening copolymers of a monomer having a norbornene structure and any monomer capable of copolymerizing therewith. Moreover, examples of addition polymers of monomers having a norbornene structure include: addition homopolymers of a single monomer having a norbornene structure; addition copolymers of two or more monomers having a norbornene structure; and addition copolymers of a monomer having a norbornene structure and any monomer capable of copolymerizing therewith. Examples of these polymers include those disclosed in Japanese Patent Application Publication No. 2002-321302, etc.

[0062] Specific examples of norbornene polymers and their hydrides include: "ZEONOR" manufactured by Zeon Corporation of Japan; "ARTON" manufactured by JSR Corporation; and "TOPAS" manufactured by Topas Advanced Polymers.

[0063] Thermoplastic resin (P1) may contain only one alicyclic polymer or may contain two or more alicyclic polymers in any ratio.

[0064] When the thermoplastic resin (P1) contains alicyclic polymers, it is preferable that the glass transition temperature of the alicyclic polymers contained in the thermoplastic resin (P1) is different from the glass transition temperature of the alicyclic polymers contained in the thermoplastic resin (P2) described later.

[0065] The microparticles contained in thermoplastic resins (P1) can be inorganic particles, organic particles, or composite particles combining inorganic and organic materials. Microparticles can be used alone or in any combination of two or more in any ratio.

[0066] In one embodiment, the microparticles contained in the thermoplastic resin (P1) are preferably organic particles, and from the viewpoint of making it easier to adjust the refractive index of the microparticles and narrowing the width of the particle size distribution, microparticles of organic polymers are more preferred.

[0067] Examples of organic polymers capable of forming microparticles include cross-linked copolymers of methyl methacrylate and styrene, as well as cross-linked polymers containing alicyclic structures.

[0068] From the viewpoint of making it easier to adjust the refractive index, the microparticles are preferably microparticles of a cross-linked copolymer of methyl methacrylate and styrene.

[0069] A crosslinked copolymer of methyl methacrylate and styrene refers to a copolymer of methyl methacrylate, styrene, and a crosslinking monomer. Examples of crosslinking monomers include polyfunctional monomers containing two or more polymerizable groups per molecule. Specific examples include divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and tripropylene glycol dimethacrylate. The microparticles of the above-mentioned crosslinked copolymers can be obtained, for example, by suspension polymerization of a monomer mixture containing methyl methacrylate, styrene, and the crosslinking monomer. The weight ratio of methyl methacrylate, styrene, and the crosslinking monomer can be arbitrarily set.

[0070] As the microparticles of the cross-linked polymer of methyl methacrylate and styrene mentioned above, microparticles of various average particle sizes are commercially available and can be used. An example of a commercially available product of such microparticles is "TECHPOLYMER" manufactured by Sekisui Chemicals Co., Ltd.

[0071] The microparticles contained in the thermoplastic resin (P1) can be microparticles of a cross-linked polymer containing an alicyclic structure. Here, a cross-linked polymer containing an alicyclic structure refers to a polymer comprising a structure formed by cross-linking repeating units containing an alicyclic structure. Examples and preferred examples of the alicyclic structure contained in the cross-linked polymer containing an alicyclic structure, preferred ranges of the number of carbon atoms constituting the alicyclic structure, and preferred ranges of the proportion of repeating units containing the alicyclic structure are the same as those described for polymers containing an alicyclic structure. When the thermoplastic resin (P1) contains a polymer containing an alicyclic structure, by making the microparticles into microparticles of a cross-linked polymer containing an alicyclic structure, the refractive index of the microparticles can be made close to the refractive index of the polymer containing the alicyclic structure, thereby effectively reducing the internal haze of the multilayer stretched film.

[0072] Examples of crosslinked polymers containing alicyclic structures include norbornene-based crosslinked polymers, monocyclic cyclic olefin-based crosslinked polymers, cyclic conjugated diene-based crosslinked polymers, vinyl alicyclic hydrocarbon-based crosslinked polymers, and their hydrides. Among these, norbornene-based crosslinked polymers and their hydrides are preferred due to their good transparency.

[0073] Examples of norbornene-based crosslinked polymers include: crosslinked polymers of monomer units having a norbornene structure and their hydrides; crosslinked polymers of copolymers of monomers having a norbornene structure and any monomers capable of copolymerizing with them, and their hydrides. The copolymers can be ring-opening copolymers of monomers having a norbornene structure or addition copolymers.

[0074] As a crosslinked polymer with an alicyclic structure, particles that are crosslinked by suspending polymerization of monomers having a norbornene structure in the presence of a crosslinking agent, and particles that are crosslinked by crosslinking polymers having a norbornene structure in the presence of a crosslinking agent can be used.

[0075] The microparticles contained in thermoplastic resins (P1) can be inorganic particles. Examples of inorganic particles include silica particles, synthetic zeolite particles, and glass particles.

[0076] In one embodiment, from the viewpoint of achieving a uniform particle size distribution, the microparticles contained in the thermoplastic resin (P1) are preferably silica microparticles.

[0077] As microparticles of silica, commercially available microparticles of various average particle sizes are available for use. Examples of commercially available products include the "QSG" series manufactured by Shin-Etsu Chemical Industry Co., Ltd., the "SEAHOSTAR" series manufactured by Nippon Shokubai Co., Ltd., and the "ADMANANO" series manufactured by Aduma Technology Co., Ltd.

[0078] The number-average particle size D of the microparticles is preferably 0.10 μm or more, more preferably 0.20 μm or more, more preferably 0.80 μm or less, and more preferably 0.50 μm or less. When the number-average particle size D is above or below the above-mentioned lower limit, the sliding properties of the multilayer stretched film can be improved. By making the number-average particle size D below or below the above-mentioned upper limit, the internal haze of the multilayer stretched film can be effectively reduced.

[0079] The number-average particle size D of the particles can be determined using a particle size distribution measuring device via laser diffraction scattering.

[0080] The particulate content in the thermoplastic resin (P1) is preferably 0.5% by weight or more, more preferably 1% by weight or more, more preferably 10% by weight or less, more preferably 9% by weight or less, and even more preferably 8% by weight or less. When the particulate content in the thermoplastic resin (P1) is above the lower limit mentioned above, the sliding properties of the multilayer stretched film are more excellent. By keeping the particulate content below the upper limit mentioned above, the surface roughness of the stretched layer (L1) can be made to a suitable surface roughness and the increase of external haze of the laminated film can be suppressed.

[0081] Thermoplastic resin (P1) may contain any components in addition to polymers and microparticles. Examples of such components include: stabilizers such as antioxidants, heat stabilizers, and near-infrared absorbers; resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments; and antistatic agents. Thermoplastic resin (P1) may contain only one of these components or may contain two or more of these components in any combination at any ratio. The total proportion of any components in the thermoplastic resin (P1) is preferably 30% by weight or less, more preferably 20% by weight or less, even more preferably 10% by weight or less, typically 0% by weight or more, and may be 0.01% by weight or more, 0.1% by weight or more, or 1% by weight or more.

[0082] The glass transition temperature Tg1 of the thermoplastic resin (P1) is preferably 40°C or higher, more preferably 70°C or higher, even more preferably 90°C or higher, preferably 180°C or lower, more preferably 160°C or lower, and even more preferably 140°C or lower, provided that the condition of satisfying formula (1) is met.

[0083] A multilayer stretched film may contain two stretched layers (L1). In the case of a multilayer stretched film containing two stretched layers (L1), the first stretched layer (L1) and the second stretched layer (L1) are sometimes referred to as stretched layer (L1-a) and stretched layer (L1-b), respectively. In the case of a multilayer stretched film containing two stretched layers (L1), a stretched layer (L2) is provided between stretched layer (L1-a) and stretched layer (L1-b).

[0084] The thickness T1 of the stretch layer (L1) is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.5 μm or more, preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. Here, in the case where the multilayer stretch film has two stretch layers (L1), the thickness T1 of the stretch layer (L1) is the thickness of one stretch layer (L1).

[0085] Preferably, the thickness T1 of the stretch layer (L1) is smaller than the thickness T2 of the stretch layer (L2) described later. This improves the slip properties of the stretch layer (L1) and effectively reduces the haze of the multilayer stretch film.

[0086] The ratio (T1 / T2) of the thickness T1 of the stretched layer (L1) to the thickness T2 of the stretched layer (L2) is preferably 1 / 1000 or more, more preferably 1 / 100 or more, preferably 1 / 5 or less, more preferably 1 / 10 or less, and more preferably 1 / 20 or less.

[0087] When the number-average particle size is D (μm), the thickness T1 (μm) of the stretch layer (L1) is preferably 10×Dμm or less, more preferably 5×Dμm or less, more preferably 1×Dμm or more, and more preferably 2×Dμm or more. This can effectively improve the impact strength of the multilayer stretch film.

[0088] [2.2. Tension Layer (L2)]

[0089] The stretched layer (L2) is a stretched layer containing thermoplastic resin (P2) and formed from thermoplastic resin (P2). The thermoplastic resin (P2) contains an alicyclic polymer. The alicyclic polymer contained in the thermoplastic resin (P2) can be appropriately selected from examples and preferred examples of alicyclic polymers that can be contained in the stretched layer (L1) described above.

[0090] Provided that the effects of the invention are not significantly impaired, the thermoplastic resin (P2) may contain any polymer other than alicyclic polymers; however, from the viewpoint of significantly maximizing the advantages of the invention, it is preferable that the amount of any polymer is small. The specific amount of any polymer can vary depending on factors such as the application and thickness of the multilayer stretched film. For example, relative to 100 parts by weight of the thermoplastic resin (P2), the proportion of the aforementioned any polymer is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 3 parts by weight or less, typically 0 parts by weight or more, and may be 0 parts by weight. The thermoplastic resin (P2) is particularly preferably free of any polymer.

[0091] The thermoplastic resin (P2) may contain an ultraviolet absorber. This enables the multilayer stretch film of this embodiment to acquire resistance to ultraviolet light. Therefore, when the multilayer stretch film of this embodiment is used as an optical film such as a polarizer protective film, it is possible to effectively protect the multilayer stretch film of this embodiment and the protected object such as the polarizer protected by the multilayer stretch film from deterioration due to ultraviolet light.

[0092] As ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, acrylonitrile-based ultraviolet absorbers, and hydroxyphenyltriazine-based ultraviolet absorbers can be used. As ultraviolet absorbers, 2,2′-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol, and 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, etc., are particularly preferred. Furthermore, one ultraviolet absorber may be used, or two or more may be used in any ratio.

[0093] The content of the ultraviolet absorber in the thermoplastic resin (P2) is preferably 1.0% by weight or more, more preferably 2.0% by weight or more, more preferably 15% by weight or less, and more preferably 10% by weight or less. When the content of the ultraviolet absorber is at or above the lower limit of the above range, it can effectively block ultraviolet rays. When the content of the ultraviolet absorber is at or below the upper limit of the above range, it can suppress the generation of point defects in the multilayer stretched film caused by poor dispersion of the ultraviolet absorber, and further suppress the reduction of strength of the multilayer stretched film.

[0094] In addition to the alicyclic polymers described above, thermoplastic resin (P2) may also contain any components other than ultraviolet absorbers. Examples of any components that can be contained in thermoplastic resin (P1) can be cited as examples of such components. Thermoplastic resin (P2) may contain only one such component, or it may contain two or more such components in any ratio.

[0095] The thermoplastic resin (P2) preferably contains no particulate matter. The particulate matter content in the thermoplastic resin (P2) is preferably 3% by weight or less, more preferably 1% by weight or less, even more preferably 0.5% by weight or less, preferably 0% by weight, and can be 0.1% by weight or more. By ensuring that the thermoplastic resin (P2) contains no particulate matter, the haze of the stretch layer (L2) can be reduced, resulting in a highly transparent multilayer stretch film.

[0096] The glass transition temperature Tg2 of the thermoplastic resin (P2) is preferably 50°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, preferably 200°C or lower, and more preferably 180°C or lower, provided that the glass transition temperature Tg2 satisfies Formula (1).

[0097] The thickness T2 of the stretch layer (L2) is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, preferably 300 μm or less, more preferably 150 μm or less, and even more preferably 50 μm or less. By making the thickness T2 of the stretch layer (L2) at or above the above-mentioned lower limit value, the strength of the multilayer stretch film can be improved and the in-plane phase difference can be increased. By making the thickness T2 of the stretch layer (L2) at or below the above-mentioned upper limit value, the multilayer stretch film can be thinned.

[0098] [2.3. Arbitrary Layers]

[0099] In addition to the stretch layer (L1) and stretch layer (L2) mentioned above, the multilayer stretch film can also contain any other layers. As an example of any other layer, an adhesive layer that serves as an adhesive layer can be given.

[0100] [3. Characteristics of multilayer stretched films]

[0101] (Birefringence Δn)

[0102] The birefringence Δn of the multilayer stretched film is preferably 0.001 or more, more preferably 0.002 or more, and even more preferably 0.003 or more. Since the higher the birefringence Δn, the thinner the multilayer stretched film can be, it is preferred. The birefringence Δn can be, for example, 0.010 or less.

[0103] The birefringence Δn can be calculated using the in-plane phase difference Re (nm) and the film thickness d3 (nm) by the following formula.

[0104] Δn=Re / d3

[0105] The static friction coefficient of the multilayer stretched film is preferably below 1 μs, more preferably below 0.8 μs, even more preferably below 0.7 μs, and typically above 0 μs, which can be above 0.1 μs. A lower static friction coefficient results in better sliding properties, reduces adhesion of the multilayer stretched film, and suppresses optical defects such as scratches. The static friction coefficient of the multilayer stretched film can be measured using a friction testing machine according to JIS K7125. The measurement can be performed with a test piece of 140 mm × 65 mm, a load of 1 kgf, and a speed of 500 mm / min.

[0106] The internal haze of the multilayer stretched film is preferably less than 1%, more preferably less than 0.5%, and even more preferably less than 0.1%. The lower the internal haze, the more preferred it is, and it can be more than 0.01%.

[0107] By making the internal haze of the multilayer stretched film so low, the multilayer stretched film can be preferred as an optical film requiring high optical performance.

[0108] [4. Implementation Method 1]

[0109] Hereinafter, the structure of a multilayer stretch film according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0110] Figure 1 A cross-sectional view of the multilayer stretched film of Embodiment 1 is shown schematically.

[0111] like Figure 1 As shown, the multilayer stretch film 100 of Embodiment 1 has a stretch layer 110 as a stretch layer (L1) and a stretch layer 120 as a stretch layer (L2). The stretch layer 110 is disposed on the outermost side of the multilayer stretch film 100, and one side of the stretch layer 110 has its main surface 110U exposed. The other side of the stretch layer 110 has its main surface 110D in contact with the main surface 120U of the stretch layer 120. The stretch layer 110 and the main surface 120U of the stretch layer 120 are in contact. In this embodiment, the main surface 110D of the stretch layer 110 and the main surface 120U of the stretch layer 120 are in direct contact without any layer in between. In other embodiments, the main surface 110D of the stretch layer 110 and the main surface 120U of the stretch layer 120 may be in contact with each other through an adhesive layer or any other layer.

[0112] In the structure of this embodiment, since the stretching layer (L1) containing microparticles is only the stretching layer 110, the haze of the multilayer stretch film can be reduced. In addition, the manufacturing process is simple due to the small number of layers.

[0113] [5. Implementation Method 2]

[0114] Figure 2 A cross-sectional view of the multilayer stretched film of Embodiment 2 is shown schematically.

[0115] like Figure 2 As shown, the multilayer stretched film 200 of Embodiment 2 sequentially includes a stretch layer 211 as a first stretch layer (L1), a stretch layer 220 as a stretch layer (L2), and a stretch layer 212 as a second stretch layer (L1). Stretch layers 211 and 212 are disposed on the outermost side of the multilayer stretched film 200. One side of the main surface 211U of stretch layer 211 is exposed, and one side of the main surface 212D of stretch layer 212 is exposed. The other side of the main surface 211D of stretch layer 211 is in contact with the main surface 220U of stretch layer 220. Stretch layer 211 is in contact with the main surface 220U of stretch layer 220. The other side of the main surface 212U of stretch layer 212 is in contact with the other side of the main surface 220D of stretch layer 220. Stretch layer 212 is in contact with the main surface 220D of stretch layer 220.

[0116] In this embodiment, the main surface 211D of the stretch layer 211 is in direct contact with the main surface 220U of the stretch layer 220, without any layer in between. In other embodiments, the main surface 211D of the stretch layer 211 and the main surface 220U of the stretch layer 220 may be in contact with each other through any layer such as an adhesive layer.

[0117] Furthermore, in this embodiment, the main surface 212U of the stretch layer 212 is in direct contact with the main surface 220D of the stretch layer 220, without any layer in between. In another embodiment, the main surface 212U of the stretch layer 212 and the main surface 220D of the stretch layer 220 may be in contact with each other through any layer such as an adhesive layer.

[0118] In this embodiment, since the stretch layer (L1) containing particles consists of two layers, stretch layer 211 and stretch layer 212, and stretch layer 211 and stretch layer 212 are respectively disposed on the outer side of stretch layer 220, which serves as stretch layer (L2), the slip properties of the multilayer stretch film can be improved. Furthermore, when stretch layer 220 contains any component such as an ultraviolet absorber, the exudation of any component can be suppressed.

[0119] [6. Applications of multilayer stretch films]

[0120] Multilayer stretch films reduce the exposure of microparticles on the surface of the stretch layer (L1). Therefore, it is possible to produce stretch films with good sliding properties, reduced defects caused by detached microparticles, and excellent optical properties.

[0121] Multilayer stretched films are preferably used as phase retardation films such as λ / 2 waveplates and λ / 4 waveplates. Furthermore, combining multilayer stretched films with linear polarizers makes them ideal for use as optical components such as circular polarizers and anti-reflective films.

[0122] Here, "piece" includes not only rigid components but also flexible components.

[0123] [7. Manufacturing method of multilayer stretched film]

[0124] [7.1. Overview of Manufacturing Method]

[0125] The aforementioned multilayer stretched film can be manufactured by any method.

[0126] The preferred multilayer stretch film can be manufactured by a manufacturing method including the following steps (1) and (2).

[0127] Step (1): A step of obtaining a laminate containing a resin layer (L2′) and at least one resin layer (L1′), wherein the resin layer (L1′) contains the thermoplastic resin (P1), the resin layer (L2′) contains the thermoplastic resin (P2), and the resin layer (L1′) is disposed on the outermost side of the laminate.

[0128] Process (2): The process of stretching the above-mentioned laminate.

[0129] Steps (1) and (2) are typically performed in this order. In addition to steps (1) and (2), the method for manufacturing the multilayer stretched film of this embodiment can also include any other steps.

[0130] By stretching the resin layer (L1′) and resin layer (L2′) in the laminate in step (2), the stretched layer (L1) and stretched layer (L2) can be obtained from the resin layer (L1′) and resin layer (L2′), respectively.

[0131] The laminate may contain two resin layers (L1′). When the laminate contains two resin layers (L1′), the first resin layer (L1′) and the second resin layer (L1′) are sometimes referred to as resin layer (L1′-a) and resin layer (L1′-b), respectively. In the case of the laminate containing two resin layers (L1′), a resin layer (L2′) is disposed between resin layer (L1′-a) and resin layer (L1′-b).

[0132] When a layer of thermoplastic resin containing microparticles is stretched, the microparticles may sometimes be exposed on the surface of the stretched thermoplastic resin layer and fall off. According to the method for manufacturing a multilayer stretched film of this embodiment, since thermoplastic resin (P1) and thermoplastic resin (P2) satisfy formula (1), it is possible to reduce the exposure of microparticles on the surface of the stretched layer (L1) containing thermoplastic resin (P1), which contains microparticles.

[0133] In process (2), a phase difference can usually be imparted to the multilayer stretched film by stretching the laminate.

[0134] As for the stretching conditions, any condition corresponding to the desired phase difference of the multilayer stretched film can be selected. There are no restrictions on the stretching direction; examples include the length direction, width direction, and oblique direction. Here, oblique direction refers to a direction perpendicular to the thickness direction, which is neither parallel nor perpendicular to the width direction. Furthermore, the stretching direction can be one direction or two or more directions. Therefore, examples of stretching methods include: uniaxial stretching methods such as stretching the laminate along the length direction (longitudinal uniaxial stretching method), stretching the laminate along the width direction (transverse uniaxial stretching method); biaxial stretching methods such as stretching the laminate along both the length and width directions simultaneously, stretching the laminate sequentially along one of the length and width directions and then along the other direction; and stretching the laminate along an oblique direction (oblique stretching method), etc.

[0135] The stretching ratio is preferably 1.05 times or more, more preferably 1.1 times or more, preferably 5 times or less, and more preferably 3 times or less.

[0136] The stretching temperature is preferably "Tg2-20℃" or higher, more preferably "Tg2-10℃" or higher, more preferably "Tg2+30℃" or lower, and more preferably "Tg2+20℃" or lower. Here, "Tg2" represents the glass transition temperature of the thermoplastic resin (P2) contained in the resin layer (L2′).

[0137] [7.2. Implementation Method A]

[0138] In Embodiment A of the method for manufacturing a multilayer stretched film, the above-mentioned step (1) includes a step of co-extruding the above-mentioned resin layer (L1′) and the above-mentioned resin layer (L2′). By co-extruding the resin layer (L1′) and the resin layer (L2′) to obtain a laminate, a laminate with very little residual solvent can be obtained. In addition, since the resin layer (L1′) and the resin layer (L2′) are formed simultaneously by co-extrusion, the number of manufacturing steps of the laminate can be reduced. Furthermore, by continuously co-extruding the resin layer (L1′) and the resin layer (L2′), a long strip laminate can be easily obtained.

[0139] There are no particular limitations on the co-extrusion method, and examples include co-extrusion T-die method, co-extrusion blow molding method, and co-extrusion lamination method, with co-extrusion T-die method being particularly preferred. Examples of co-extrusion T-die method include feed head method and multi-manifold method. From the viewpoint of simple manufacturing, feed head method is preferred, and from the viewpoint of reducing thickness deviation, multi-manifold method is preferred.

[0140] The extrusion processing temperature (the highest temperature in the barrel heating zone) is preferably "Tg+80℃" or higher, more preferably "Tg+100℃" or higher, more preferably "Tg+180℃" or lower, and more preferably "Tg+150℃" or lower. Here, "Tg" represents the glass transition temperature of the thermoplastic resin fed into the extruder.

[0141] The co-extruded laminate containing resin layer (L1′) and the aforementioned resin layer (L2′) is typically cooled using a cooling component such as a cooling cylinder.

[0142] For example, the temperature of the cooling cylinder is preferably "Tg2-100℃" or higher, more preferably "Tg2-70℃" or higher, more preferably "Tg2-5℃" or lower, and more preferably "Tg2-10℃" or lower. Here, "Tg2" represents the glass transition temperature of the thermoplastic resin (P2) contained in the resin layer (L2′).

[0143] When the laminate contains two resin layers (L1′), the laminate can be obtained by co-extruding resin layers (L1′-a), (L2′), and (L1′-b) in a state of sequential overlap along the thickness direction.

[0144] [7.3. Implementation Method B]

[0145] In Embodiment B of the method for manufacturing a multilayer stretch film, the above-mentioned step (1) includes a step of coating the main surface of the above-mentioned resin layer (L2′) with a composition comprising the above-mentioned thermoplastic resin (P1).

[0146] The resin layer (L2′) can be manufactured by any method, such as melt molding or solution casting.

[0147] By forming the resin layer (L2′) into a strip and continuously coating it with a composition containing thermoplastic resin (P1), a long strip laminate can be obtained.

[0148] When a laminate comprises two resin layers (L1′), the laminate can be obtained by coating the two main surfaces of the resin layer (L2′) with a composition comprising a thermoplastic resin (P1). The coating of the composition on the two main surfaces of the resin layer (L2′) can be performed sequentially or simultaneously.

[0149] The composition coated on the resin layer (L2′) is typically a liquid composition comprising a thermoplastic resin (P1) and a solvent. Examples of solvents include ester solvents (e.g., methyl acetate, ethyl acetate), ketone solvents (e.g., acetone, methyl ethyl ketone, cyclopentanone), ether solvents (e.g., tetrahydrofuran, cyclopentylmethyl ether), hydrocarbon solvents (e.g., hexane, cyclohexane, methylcyclohexane, toluene, xylene), and halogenated hydrocarbon solvents (e.g., dichloromethane). Furthermore, a single solvent may be used, or two or more solvents may be used in any ratio.

[0150] Examples of coating methods for the composition include curtain coating, extrusion coating, roller coating, spin coating, dip coating, bar coating, spray coating, sliding coating, printing coating, gravure coating, die coating, and slot coating.

[0151] Step (1) may further include a step of drying the composition coated on the main surface of the resin layer (L2′). Drying can be carried out by, for example, natural drying, heat drying, vacuum drying, vacuum heating drying, etc.

[0152] [7.4. Implementation Method C]

[0153] In embodiment C of the method for manufacturing a multilayer stretch film, the above-mentioned step (1) includes the step of extruding the above-mentioned thermoplastic resin (P1) on the main surface of the above-mentioned resin layer (L2′).

[0154] By forming the resin layer (L2′) into a strip and continuously extruding thermoplastic resin (P1) on its main surface, a long strip laminate can be obtained.

[0155] When a laminate comprises two resin layers (L1′), the laminate can be obtained by extruding a composition comprising thermoplastic resin (P1) onto each of the two main surfaces of the resin layer (L2′). The extrusion of the composition onto the two main surfaces of the resin layer (L2′) can be performed sequentially or simultaneously.

[0156] The extrusion temperature of the thermoplastic resin (P1) can be set according to the glass transition temperature Tg1 of the thermoplastic resin (P1).

[0157] [7.5. Implementation Method D]

[0158] In embodiment D of the method for manufacturing a multilayer stretch film, the above-mentioned step (1) includes a step of bonding the above-mentioned resin layer (L1′) and the above-mentioned resin layer (L2′).

[0159] The resin layer (L1′) and resin layer (L2′) can be manufactured by any method, such as melt molding or solution casting.

[0160] A laminate can be obtained by bonding resin layers (L1′) and (L2′). A strip-shaped laminate can be obtained by using strip-shaped films as resin layers (L1′) and (L2′) respectively, and bonding them parallel to each other along their length. Pressure-sensitive adhesives or other adhesives can be used as needed during bonding.

[0161] When the laminate contains two resin layers (L1′), the laminate can be obtained by bonding resin layers (L1′-a) and (L1′-b) to the two main surfaces of the resin layer (L2′).

[0162] Example

[0163] The present invention will now be specifically described with reference to the embodiments shown below. However, the present invention is not limited to the embodiments shown below, and can be implemented in any way without departing from the scope of the claims and their equivalents.

[0164] Unless otherwise stated, in the following instructions, "%" and "parts" refer to quantities based on weight. Furthermore, unless otherwise stated, the operations described below are performed at room temperature (20℃±15℃) and normal pressure (1 atm).

[0165] [Evaluation Method]

[0166] (Thickness of each layer of the multilayer stretch film)

[0167] The multilayer stretched film was cut, and the cross-section was cut using a slicer (Yawa Koki Co., Ltd. "RV-240") to prepare a sample. Then, the cross-section of the film was imaged using an electron microscope, and the thickness of each layer was measured.

[0168] (Glass transition temperature)

[0169] The glass transition temperatures of resin 1, resin 2, and the materials forming the film (thermoplastic resin (P1) and thermoplastic resin (P2)) were determined in a nitrogen environment using a "DSC7020" manufactured by Hitachi, Ltd. Conditions were based on JIS K7121-1987, with a heating rate of 20°C / min, and the glass transition onset temperature was determined by extrapolation. The glass transition temperature of this invention refers to this glass transition onset temperature. The sample was preheated at 300°C for 10 minutes in a nitrogen environment, then rapidly cooled with liquid nitrogen, and the glass transition temperature was then measured.

[0170] (Evaluation of the coating state of particles)

[0171] The surface of layer (L1-a) of the multilayer stretched film was observed using an electron microscope at 3000x magnification over a region of 30 μm longitudinally and 40 μm laterally. The presence of microparticles was confirmed within the observation area. The observation area was changed, and the observation was repeated five times. A case where no microparticles were observed in any of the five observations was rated as good, while a case where microparticles were observed in more than one observation was rated as poor.

[0172] (Determination of Δn)

[0173] The in-plane phase difference (Re) of the film at a wavelength of 590 nm was measured using a phase difference meter (AxoScan, manufactured by Axometrics). The birefringence Δn was calculated using the obtained in-plane phase difference by the following formula.

[0174] Δn=Re÷d3

[0175] As d3, the total thickness (in nm) of each layer of the multilayer stretched film is used.

[0176] (Measurement of internal haze)

[0177] A zinc bromide aqueous solution (refractive index 1.53) diluted with pure water was placed inside a quartz unit measuring 55 mm in height, 40 mm in length, and 14 mm in width. The quartz unit was then mounted in a haze meter (NDH7000, manufactured by Nippon Denshoku Co., Ltd.) to measure the haze and perform zeroing. Next, a multilayer stretched film was cut into rectangles, and the cut film pieces were inserted into the aforementioned quartz unit. The quartz unit with the inserted film pieces was then mounted in a haze meter (NDH7000, manufactured by Nippon Denshoku Co., Ltd.) to measure the internal haze of the film.

[0178] (Determination of static friction coefficient)

[0179] The static friction coefficient of multilayer stretched films was determined using a friction testing machine (TR-2, manufactured by Toyo Seiki Co., Ltd.) according to JIS K7125. The test was conducted under the conditions of a test piece size of 140 mm × 65 mm, a load of 1 kgf, and a speed of 500 mm / min. The lower the static friction coefficient, the greater the sliding property of the film.

[0180] [Materials used in the examples and comparative examples]

[0181] (Resin 1 or Resin 2: Resins containing polymers with alicyclic structures)

[0182] Hydrogenate 1 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 99°C

[0183] Hydrogenate 2 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 125°C

[0184] Hydrogenate 3 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 134°C

[0185] Hydrogenate 4 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 160℃

[0186] (particle)

[0187] "TECHPOLYMER": Polymer beads manufactured by Sekisui Chemicals Co., Ltd., microparticles of a crosslinked copolymer of methyl methacrylate and styrene, with a number average particle size of 0.4 μm.

[0188] (UV absorber)

[0189] "ADK STAB LA-31": Manufactured by ADK Corporation, a benzotriazole-based ultraviolet absorber, containing 2,2′-methylenebis[6-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol].

[0190] [Examples 1-13, Comparative Examples 1-4]

[0191] (1. The process of preparing thermoplastic resin (P1))

[0192] As a material for forming the stretched layer (L1), 97 parts by weight of resin 1 as described in Tables 1 to 4 and 3 parts by weight of microparticles were fed into a co-rotating biaxial mixer (Parker Corporation "HK-25D", φ = 25 mm, L / D = 41) and mixed at a mixing temperature corresponding to that of resin 1 shown below to prepare a thermoplastic resin (P1) containing microparticles.

[0193] Resin 1: Hydrogenated form of norbornene polymer 1: Mixing temperature 220℃

[0194] Resin 1: Hydrogenated form of norbornene polymer; Mixing temperature 240℃

[0195] Resin 1: Hydrogenated form of norbornene polymer; 3: Mixing temperature 250℃

[0196] Resin 1: Hydrogenated form of norbornene polymer; 4: Mixing temperature 285℃

[0197] (2. The process of preparing thermoplastic resin (P2))

[0198] Thermoplastic resin (P2) was prepared as the material for forming the stretched layer (L2). In Examples 1-3, 9-12, and Comparative Examples 1-4, commercially available resin 2 shown in Tables 1-4 was used directly.

[0199] In Examples 4-8 and 13, resin 2 as shown in Table 2 or 3 and the ultraviolet absorber "ADK STAB LA-31" were fed into a co-rotating twin-shaft mixer (Parker Corporation "HK-25D", φ = 25 mm, L / D = 41) and mixed at a mixing temperature corresponding to that of resin 2 shown below to prepare thermoplastic resin (P2). Here, resin 2 and the ultraviolet absorber were fed into the mixer at a weight ratio where the content of the ultraviolet absorber in the thermoplastic resin (P2) was the value shown in Table 2 or 3.

[0200] Resin 2: Hydrogenated form of norbornene polymer; Mixing temperature 240℃

[0201] Resin 2: Hydrogenated form of norbornene polymer; Mixing temperature 285℃

[0202] (3. Process for obtaining the laminate (1))

[0203] Long, laminated films were manufactured by co-extrusion using three types of three-layer / multilayer extruders (manufactured by Collin Corporation) equipped with feed heads. The feed heads have a structure capable of forming a laminate with a three-layer structure consisting of a first layer, a second layer, and a third layer. Thermoplastic resins as shown in Tables 1-4 were used as materials supplied to the first, second, and third layers. Thermoplastic resins (P1) as shown in Tables 1-4 were supplied to the first and third layers, which are the outermost layers. The same resin (P1) was supplied to the first and third layers. Thermoplastic resins (P2) as shown in Tables 1-4 were supplied to the second layer, which is located between the first and third layers. The molten resin was extruded from the die of the extruder and cooled in a cooling cylinder to obtain a laminated film as a laminated body. The extrusion processing temperature (the highest temperature in the barrel heating zone) and the temperature of the cooling cylinder are shown in Tables 1-4. The resulting laminated film sequentially has a first layer, a second layer, and a third layer. The first layer is a resin layer (L1′-a) containing thermoplastic resin (P1). The second layer is a resin layer (L2′) containing thermoplastic resin (P2). The third layer is a resin layer (L1′-b) containing thermoplastic resin (P1).

[0204] (4. The process of stretching the laminate (2))

[0205] Using the direction perpendicular to the length direction (width direction) as the stretching direction, the resulting long strip of laminated film was subjected to fixed uniaxial stretching at the stretching ratios and stretching temperatures shown in Tables 1-4, resulting in a multilayer stretched film. The multilayer stretched film sequentially comprises <a stretched layer (L1-a) containing thermoplastic resin (P1) obtained by stretching the first layer (resin layer (L1′-a))>, <a stretched layer (L2) containing thermoplastic resin (P2) obtained by stretching the second layer (resin layer (L2′))>, and <a stretched layer (L1-b) containing thermoplastic resin (P1) obtained by stretching the third layer (resin layer (L1′-b))>.

[0206] The results of observing the surface of the stretched layer (L1-a), the thickness of each layer of the obtained multilayer stretched film, Δn, internal haze, and the measured values ​​of the static friction coefficient are shown in Tables 1 to 4.

[0207] In the table below, the abbreviations have the following meanings.

[0208] "H1": Hydroxide 1 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 99°C

[0209] "H2": Hydrogenate 2 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 125℃

[0210] "H3": Hydroxide 3 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 134℃

[0211] "H4": Hydrogenate 4 of norbornene polymers: manufactured by Zeon Corporation, Japan, glass transition temperature 160℃ [Table 1]

[0212] Table 1

[0213]

[0214] [Table 2]

[0215] Table 2

[0216]

[0217] [Table 3]

[0218] Table 3

[0219]

[0220] [Table 4]

[0221] Table 4

[0222]

[0223] The following can be determined from the above results.

[0224] The microparticles in the multilayer stretched film of the embodiment with Tg2-Tg1 greater than 0°C and satisfying formula (1) are well coated.

[0225] The microparticles in the comparative example of the multilayer stretched film, where Tg2-Tg1 is 0℃ and does not satisfy equation (1), have poor coating conditions.

[0226] Explanation of reference numerals in the attached figures

[0227] 100: Multilayer Stretch Film

[0228] 110: Tension layer (L1)

[0229] 110U: Main Face

[0230] 110D: Main face

[0231] 120: Stretch layer (L2)

[0232] 120U: Main Face

[0233] 120D: Main face

[0234] 200: Multilayer stretch film

[0235] 211: Stretch layer (L1)

[0236] 211U: Main Face

[0237] 211D: Main face

[0238] 212: Stretch layer (L1)

[0239] 212U: Main Face

[0240] 212D: Main face

[0241] 220: Stretch layer (L2)

[0242] 220U: Main Face

[0243] 220D: Main face

Claims

1. A multilayer stretch film, It comprises a stretch layer L2 and at least one stretch layer L1. The stretch layer L1 is disposed on the outermost side of the multilayer stretch film and contains thermoplastic resin P1, wherein the thermoplastic resin P1 contains microparticles. The stretched layer L2 comprises thermoplastic resin P2, which comprises a polymer with an alicyclic structure. The thermoplastic resin P1 and the thermoplastic resin P2 satisfy the following formula (1): ， Here, Tg1 represents the glass transition temperature of the thermoplastic resin P1, and Tg2 represents the glass transition temperature of the thermoplastic resin P2. The number-average particle size D of the particles is greater than 0.10 μm and less than 0.80 μm. The content of the microparticles in the thermoplastic resin P1 is more than 0.5% by weight and less than 10% by weight.

2. The multilayer stretched film according to claim 1, wherein, The thermoplastic resin P1 and the thermoplastic resin P2 satisfy the following formula (2): 。 3. The multilayer stretch film according to claim 1, wherein, The main surfaces of the stretching layer L1 and the stretching layer L2 are in contact.

4. The multilayer stretched film according to claim 1, wherein, The multilayer stretch film comprises two stretch layers L1.

5. The multilayer stretch film according to claim 1, wherein, The thickness of the stretching layer L1 is smaller than the thickness of the stretching layer L2.

6. The multilayer stretched film according to claim 1, wherein, The thermoplastic resin P1 contains silica particles or cross-linked polymer particles.

7. The multilayer stretched film according to claim 1, wherein, The birefringence Δn of the multilayer stretched film is greater than 0.

002.

8. A method for manufacturing a multilayer stretch film, as described in any one of claims 1 to 7, comprising the following steps: Step 1, obtaining a laminate comprising a resin layer L2′ and at least one resin layer L1′, wherein the resin layer L1′ comprises the thermoplastic resin P1, the resin layer L2′ comprises the thermoplastic resin P2, and the resin layer L1′ is disposed on the outermost side of the laminate; and Step 2: Stretch the laminated body.

9. The method for manufacturing a multilayer stretched film according to claim 8, wherein, Step 1 includes the process of co-extruding the resin layer L1′ and the resin layer L2′.

10. The method for manufacturing a multilayer stretched film according to claim 8, wherein, Step 1 includes the step of coating the main surface of the resin layer L2′ with a composition comprising the thermoplastic resin P1.

11. The method for manufacturing a multilayer stretched film according to claim 8, wherein, The process 1 includes the process of extruding the thermoplastic resin P1 on the main surface of the resin layer L2′.

12. The method for manufacturing a multilayer stretched film according to claim 8, wherein, Step 1 includes the process of bonding the resin layer L1′ and the resin layer L2′ together.

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