Laminated film for decoration

Abstract

To provide a laminated film that is formed by laminating an acrylic resin film and a vinylidene fluoride-based resin film, and is a matted film with low glossiness, which has low glossiness even after having been stretched while heated, and has high transparency before and after stretching.SOLUTION: A laminated film for decoration is formed by laminating an acrylic resin film and a vinylidene fluoride-based resin film. As for the laminated film, a 60° glossiness value measured in a non-stretched manner is 10% or more and 60% or less, a haze is 10% or more and 50% or less, a 60° glossiness value stretched at 120°C and 140% is 10% or more and 60% or less, and a haze is 10% or more and 50% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a decorative laminate film. [Background technology]

[0002] Decorative films are often applied to automobiles, home appliances, furniture, buildings, etc. to improve durability and decoration. In particular, for the interior and exterior of automobiles, replacing the conventional paint with decorative films is expected to improve design, reduce weight, simplify the manufacturing process, and reduce environmental pollution caused by solvents contained in paint.

[0003] As a decorative film, a highly transparent acrylic resin film (hereinafter, acrylic resin may be referred to as "AC resin" and acrylic resin film may be referred to as "AC resin film") is used so as not to impair the design expression of the base material. On the other hand, AC resin film has poor chemical resistance, so it is used as a laminate film laminated with a vinylidene fluoride resin film (hereinafter, vinylidene fluoride resin may be referred to as "VDF resin" and vinylidene fluoride resin film may be referred to as "VDF resin film"), which has excellent chemical resistance, weather resistance, scratch resistance, etc. (Patent Document 1, Patent Document 2, etc.).

[0004] Decorative films are attached to the surface of a substrate while being heated and stretched by methods such as vacuum forming, compressed air forming, etc. To improve stretchability during molding, acrylic resins are sometimes mixed into VDF-based resin films used in decorative films (Patent Document 1, Patent Document 2, etc.).

[0005] Furthermore, when used in applications requiring a luxurious feel, such as automobiles, matte films with reduced gloss are sometimes used as decorative films. Matte films are produced by methods such as transferring the irregularities to the film surface using a matte roll with fine irregularities on the surface, or by adding a fine filler (matting agent) to the film (Patent Document 3, etc.). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-187934 [Patent Document 2] International Publication No. 2021 / 161899 [Patent Document 3] International Publication No. 2016 / 010051 Summary of the Invention [Problem to be solved by the invention]

[0007] Matte films made by reducing the gloss of decorative films using only a matte roll can have their surface irregularities reduced and their gloss restored due to the heat history during molding, such as vacuum molding or pressure molding. In contrast, matte films made by reducing the gloss using a matting agent do not lose their gloss due to the heat history during molding. However, when a matting agent is added to a VDF-based resin film, the matting agent acts as a crystal nucleating agent, increasing the crystallinity of the VDF-based resin, thereby reducing the stretchability and transparency of the matte film.

[0008] Furthermore, as described in Patent Documents 1 and 2, a method is known in which an AC resin is mixed with a VDF resin film to enhance the stretchability of the laminated film. This method is thought to enhance the stretchability of the matte film. However, mixing an AC resin with a VDF resin film reduces the transparency of the matte film after stretching.

[0009] On the other hand, although the transparency of a VDF resin film to which a matting agent has been added decreases as described above, the transparency does not decrease (the haze does not increase) even when stretched while heated. However, according to the findings of the present inventors, a problem has been found in that the transparency of a laminated film in which a VDF resin film to which a matting agent has been added is laminated with an AC resin film is decreased when stretched while heated.

[0010] The present invention has been made in view of the above problems, and has an object to provide a laminated film which is a low-gloss matte film formed by laminating an AC-based resin film and a VDF-based resin film, and which has low gloss even after being stretched while being heated, and which has high transparency both before and after stretching. [Means for solving the problem]

[0011] One embodiment of the present invention for solving the above problems relates to the following decorative laminate films [1] to [7]. [1] A laminated film for decoration, comprising an acrylic resin film and a vinylidene fluoride resin film laminated together, wherein the laminated film has a 60° gloss value of 10% or more and 60% or less and a haze of 10% or more and 50% or less when measured unstretched, and the laminated film has a 60° gloss value of 10% or more and 60% or less and a haze of 10% or more and 50% or less when stretched to 140% at 120°C. [2] The decorative laminate film according to [1], wherein the laminate film has a breaking elongation of 100% or more and 400% or less at 23°C. [3] The decorative laminate film according to [1] or [2], wherein the vinylidene fluoride resin film has a thickness (T1) of 1 μm or more and 30 μm or less. [4] The decorative laminate film according to any one of [1] to [3], wherein the vinylidene fluoride resin film contains a vinylidene fluoride resin having an inherent viscosity of 0.80 dL / g or more and 1.20 dL / g or less. [5] The decorative laminate film according to any one of [1] to [4], wherein the vinylidene fluoride resin film contains a vinylidene fluoride resin and a matting agent in an amount of 1.0 to 20.0 parts by mass per 100 parts by mass of the vinylidene fluoride resin. [6] The decorative laminate film according to any one of [1] to [5], wherein the vinylidene fluoride resin film contains a vinylidene fluoride resin and 0.3 parts by mass or more and 5.0 parts by mass or less of an alkyl quaternary ammonium sulfate per 100 parts by mass of the vinylidene fluoride resin. [7] The decorative laminate film according to any one of [1] to [6], wherein the vinylidene fluoride resin film contains a vinylidene fluoride copolymer having a content of structural units derived from hexafluoropropylene of 1.0% by mass or more and 5.0% by mass or less. [Effects of the Invention]

[0012] According to the present invention, there is provided a laminated film which is a matte film having low gloss, in which an AC-based resin film and a VDF-based resin film are laminated together, and which has low gloss even after being stretched while being heated, and which has high transparency both before and after stretching. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Laminated film] One embodiment of the present invention relates to a decorative laminate film (hereinafter simply referred to as a "laminate film") The laminate film is formed by laminating an AC-based resin film and a VDF-based resin film.

[0014] (VDF resin film) The VDF-based resin film is a film formed from a VDF-based resin.

[0015] On the other hand, in this embodiment, the crystallinity of the VDF-based resin is maintained while the microstructure, such as the crystal size and crystal arrangement, is appropriately controlled by adding alkyl quaternary ammonium sulfate to the VDF-based resin, copolymerizing vinylidene fluoride with a fluoroolefin, optimizing the inherent viscosity of the VDF-based resin, and optimizing the cooling rate of the film during production, etc. This reduces the tensile modulus and increases the breaking elongation while maintaining the hardness of the VDF-based resin film.

[0016] The transparency of a polymer film can be evaluated by its haze. Higher haze indicates lower transparency. VDF-based resin films do not easily increase in haze when stretched alone. On the other hand, when a VDF-based resin film is laminated with an AC-based resin film, the haze of the laminated film tends to increase during stretching. The increase in haze is primarily due to an increase in the haze of the VDF-based resin film. The reason why the haze of the laminated film increases upon stretching is unclear, but the inventors believe the reason is as follows. At the interface of the laminated film, the VDF-based resin and AC-based resin are compatible, so the polymer chains of the VDF-based resin are bound to the polymer chains of the AC-based resin. In particular, the constraint of the polymer chains between the crystals of the VDF-based resin makes it impossible to relieve stress during stretching, resulting in stress concentration. In contrast, stress concentration due to stretching is low within the VDF-based resin film away from the interface with the AC-based resin. It is believed that the coexistence of areas in the film where stress concentration occurs during stretching and areas where stress concentration is relatively low creates voids between the molecular chains that make up the film, resulting in high haze in the VDF-based resin film.In contrast, in this embodiment, by appropriately controlling the microstructure, such as by loosening the arrangement of the VDF-based resin molecular chains, stress concentration is suppressed, and the occurrence of cracks and surface irregularities that increase haze when the laminate film is stretched is suppressed, thereby also suppressing a decrease in transparency after stretching.

[0017] When VDF resin is mixed with AC resin, they become compatible at a specific ratio and under specific conditions, reducing the crystallinity of the VDF resin and improving transparency. However, the compatible VDF resin and AC resin phase-separate when heated, causing the VDF resin to crystallize and become opaque. Therefore, when a VDF resin film with AC resin compatibility is vacuum-formed or pressure-formed, the thermal history during molding causes the VDF resin and AC resin to phase-separate, resulting in whitening and opacity. Furthermore, VDF resin films with reduced crystallinity due to compatibility with AC resin are prone to developing slight surface irregularities on the laminated film surface due to contact with the cooling roll during manufacturing. These irregularities then spread during stretching, causing surface roughness and resulting in reduced transparency (increased external haze). Therefore, while the method of adding methacrylic resin exhibits high transparency and low gloss before stretching, transparency decreases after hot stretching.

[0018] When an AC resin becomes miscible with a VDF resin, the glass transition temperature of the VDF resin rises, and the glass transition temperature of the VDF resin can be used as an indicator of the miscibility of the AC resin in the VDF resin. The glass transition temperature of a VDF resin film measured using a differential scanning calorimeter by heating from -90°C to 120°C at a rate of 10°C / min is preferably -50°C or higher and -10°C or lower, and more preferably -50°C or higher and -20°C or lower. When the glass transition temperature is within the above range, the miscibility of the AC resin in the VDF resin film is low, and therefore transparency is less likely to decrease during hot stretching.

[0019] The VDF-based resin may be a homopolymer of vinylidene fluoride (hereinafter sometimes abbreviated as "VDF") or a copolymer containing VDF as the main component. From the viewpoint of improving the stretchability of the laminated film, a copolymer is preferred. Examples of the copolymer include a VDF-hexafluoropropylene copolymer, a VDF-tetrafluoroethylene copolymer, and a VDF-tetrafluoroethylene-hexafluoropropylene copolymer, and from the viewpoint of improving the stretchability, a VDF-hexafluoropropylene copolymer is particularly preferred. The amount of other structural units in the copolymer (i.e., structural units derived from hexafluoropropylene or tetrafluoroethylene) is preferably 1.0% by mass or more and 5.0% by mass or less, and more preferably 1.5% by mass or more and 3.0% by mass or less. When the amount of other structural units is 1.0% by mass or more, the stretchability of the laminated film is improved, resulting in a high breaking elongation. Furthermore, the crystallinity of the VDF-based resin is appropriately reduced, making it less likely to crack during stretching, and reducing transparency after stretching due to cracking (increased internal and external haze). When the amount of other VDF structural units is 5.0% by mass or less, slight irregularities on the cooling roll with which the film comes into contact during production are less likely to be transferred to the surface of the laminated film. This unevenness then spreads during stretching, resulting in surface roughness, which reduces transparency (increased external haze). The VDF-based resin may be commercially available or may be obtained by polymerization using a conventional method.

[0020] The content of structural units other than the VDF resin in the copolymer is 19 The proportion of F atoms derived from resins other than VDF resin relative to the total F content in the VDF-based resin can be measured by F-NMR, and the content of structural units derived from resins other than VDF resin contained in the VDF-based resin can be determined.

[0021] The inherent viscosity of the VDF-based resin is preferably 0.80 dl / g or more but 1.20 dl / g or less, and more preferably 0.80 dl / g or more but 1.05 dl / g or less. Generally, as the molecular weight decreases, thermal molecular motion tends to become easier. Even in polymer compounds, the lower the degree of polymerization, the easier the molecular chain motion. Therefore, the lower the inherent viscosity, the lower the degree of polymerization, which facilitates polymer chain rearrangement upon cooling, resulting in faster crystallization and easier crystal growth. Therefore, it tends to be difficult to control the microstructure, such as by loosening the molecular chains to alleviate stress concentration during stretching. If the inherent viscosity is 0.80 dl / g or less, it becomes difficult to control the microstructure. Stress concentration due to constraints at the interface of the laminated film during stretching tends to lead to the generation of microvoids in the VDF-based resin film, resulting in increased haze. If the inherent viscosity is 0.80 dl / g or more, the stretchability of the laminated film improves, resulting in a higher breaking elongation. If the inherent viscosity exceeds 1.20 dl / g, the stretchability of the laminated film decreases, resulting in a low elongation at break, which is undesirable.

[0022] The inherent viscosity of VDF-based resin is measured in accordance with JIS K 7367-1:2002. Specifically, 80 mg of VDF-based resin is dissolved in 20 ml of N,N-dimethylformamide, and the viscosity η of the polymer solution is measured using an Ubbelohde viscometer in a thermostatic bath at 30°C. The viscosity η of the polymer solution and the viscosity η of N,N-dimethylformamide used as a solvent are then calculated. o Based on the solution concentration C (g / dl), the inherent viscosity η is calculated using the following formula: i Calculate (dl / g). η i =(1 / C)·ln(η / η o ) Here, the concentration of the solution is 0.4 (g / dl)

[0023] The VDF resin film may contain a matting agent. The matting agent may be, for example, inorganic particles or resin particles. Examples of inorganic particles include silica, alumina, zirconia, boron nitride, barium sulfate, calcium carbonate, synthetic mica, titanium oxide, and glass particles. Examples of resin particles include acrylic resin particles. If the gloss of the VDF film is reduced by a matting agent, the gloss is less likely to increase (the gloss is less likely to return) even when the laminated film is stretched.

[0024] The resin particles used as the matting agent are preferably incompatible with the VDF-based resin. In this specification, the term "matting agent is incompatible with the VDF-based resin" means that when the matting agent and the VDF-based resin are mixed and melt-extruded at a temperature equal to or higher than their glass transition temperatures, the resulting pellets are cut in a direction perpendicular to the extrusion direction of the resin, and the cut surface of the obtained test piece is observed under a transmission electron microscope, whereby a sea-island structure with island portions having a diameter of 100 nm or more is confirmed.

[0025] The resin particles may be of a crosslinked type or a non-crosslinked type, of which the crosslinked type is preferred from the viewpoint of chemical resistance.

[0026] The crosslinked particles may be particles in which a resin made from an acrylic ester, such as methyl methacrylate or n-butyl methacrylate, is crosslinked with an epoxy-based crosslinking agent or an isocyanate-based crosslinking agent.

[0027] The non-crosslinked particles are preferably particles of acrylic resin having hydroxyl groups to make them incompatible with VDF-based resins. The hydroxyl value of the acrylic resin can be 50 mgKOH / g or more and 200 mgKOH / g or less. If the hydroxyl value is 50 mgKOH / g or more, the non-crosslinked acrylic resin particles are less compatible with VDF-based resins. If the hydroxyl value is 200 mgKOH / g or less, whitening of the VDF-based resin film due to heating is less likely to occur. The hydroxyl value is calculated by acetylating the hydroxyl groups in 1 g of non-crosslinked acrylic resin particles with acetic anhydride and measuring by titration the number of mg of potassium hydroxide required to neutralize the acetic acid produced during acetylation.

[0028] From the viewpoint of sufficiently reducing gloss, the average particle size of the matting agent is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 8 μm or less. The average particle size of the matting agent is a value measured using a laser diffraction / scattering type particle size distribution measuring device.

[0029] From the viewpoint of sufficiently reducing gloss, the refractive index of the matting agent is preferably 1.45 or more and 1.60 or less, more preferably 1.48 or more and 1.53 or less. The refractive index is a value measured by Method B (Becke line detection method) of JIS K 7142:2014.

[0030] The amount of matting agent is preferably 1.0 to 20.0 parts by mass, more preferably 1.5 to 15.0 parts by mass, even more preferably 1.5 to 10.0 parts by mass, even more preferably 2.0 to 10.0 parts by mass, and particularly preferably 2.0 to 6.5 parts by mass, per 100 parts by mass of VDF-based resin. When the amount of matting agent is 1.0 part by mass or more, the gloss of the laminate film (VDF-based resin film) can be sufficiently reduced. When the amount of matting agent is 20.0 parts by mass or less, the transparency of the laminate film is ensured, allowing the design expression of the substrate covered by the laminate film to be fully visible.

[0031] The VDF resin film may contain an alkyl quaternary ammonium sulfate, which is a compound represented by the following formula (1):

[0032] [ka]

[0033] In formula (1), R 1 ~R 4 are independently alkyl groups having 1 to 10 carbon atoms. 1 ~R 4Examples of the alkyl group in R include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. 1 ~R 4 The total number of carbon atoms in the alkyl group is preferably 6 or more and 30 or less, more preferably 6 or more and 24 or less, and even more preferably 8 or more and 20 or less.

[0034] In formula (1), R 5 R is an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, or a hydrogen atom. 5 Examples of the alkyl group in R include a methyl group and an ethyl group. 5 Examples of fluoroalkyl groups in R include CF3 and C2F5. 5 is preferably hydrogen.

[0035] Examples of alkyl quaternary ammonium sulfates include (C2H5)4N + , (C3H7)4N + , (C4H9)4N + , and (CH 11 )4N + and alkyl quaternary ammonium cations such as CF3SO4 - , CH3SO4 - , and HSO4 - These compounds may be used alone or in combination of two or more.

[0036] The alkyl quaternary ammonium sulfate is preferably an alkyl quaternary ammonium hydrogen sulfate. Examples of the alkyl quaternary ammonium hydrogen sulfate include tetraethylammonium hydrogen sulfate, tetrapropylammonium hydrogen sulfate, tetrabutylammonium hydrogen sulfate, tetrapentylammonium hydrogen sulfate, and tetrahexylammonium hydrogen sulfate.

[0037] The amount of alkyl quaternary ammonium sulfate is preferably 0.3 to 5.0 parts by weight, more preferably 0.4 to 2.0 parts by weight, and even more preferably 0.6 to 1.3 parts by weight, per 100 parts by weight of VDF-based resin. When the amount of alkyl quaternary ammonium sulfate is 0.3 parts by weight or more, the microstructure of the VDF-based resin is likely appropriately controlled, thereby improving the stretchability of the VDF-based resin film. Furthermore, appropriately controlling the microstructure of the VDF-based resin is thought to reduce the occurrence of cracks in the VDF-based resin film during stretching, thereby reducing the likelihood of a decrease in transparency (increase in internal haze and external haze) after stretching. When the amount of alkyl quaternary ammonium sulfate is 5.0 parts by weight or less, the alkyl quaternary ammonium sulfate and VDF-based resin can be thoroughly mixed during the production of the VDF-based resin.

[0038] The VDF resin film may contain antioxidants, ultraviolet absorbers, light stabilizers, lubricants, release agents, antistatic agents, flame retardants, reinforcing agents, nucleating agents, bluing agents, and the like, as long as the laminated film satisfies the properties described below.

[0039] The thickness (T1) of the VDF-based resin film is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 20 μm or less, and even more preferably 3 μm or more and 13 μm or less. When the thickness (T1) is 1 μm or more, it is possible to prevent a decrease in transparency after stretching. When the thickness (T1) is 30 μm or less, it is possible to sufficiently increase the hardness of the laminated film. When the VDF-based resin film contains a matting agent, it is preferable that the thickness (T1) of the VDF-based resin film be larger than the average particle size of the matting agent.

[0040] (AC resin film) The AC-based resin film is a film formed from a known AC-based resin.

[0041] As the AC-based resin, a known homopolymer or copolymer of (meth)acrylic acid ester can be used. In this specification, (meth)acrylic means acrylic or methacrylic.

[0042] From the viewpoint of increasing the surface hardness of the laminated film, the AC-based resin is preferably a homopolymer or copolymer of a methacrylic acid ester. The methacrylic acid ester preferably has an alkyl group having from 1 to 4 carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, and t-butyl methacrylate, with methyl methacrylate being more preferred. The AC-based resin may be a copolymer of these methacrylic acid esters with other AC acid esters or vinyl monomers, but the amount of structural units derived from the methacrylic acid esters is preferably from 50 to 100% by mass, more preferably from 70 to 100% by mass, and even more preferably from 80 to 100% by mass. Commercially available AC-based resins may be used, or those obtained by polymerization using conventional methods may be used.

[0043] The AC-based resin film may contain a fluororesin such as a VDF-based resin or other resins, but the amount of AC-based resin in the AC-based resin film is from 50% to 100% by mass, preferably from 70% to 100% by mass, and more preferably from 80% to 100% by mass.

[0044] The AC resin film may contain ultraviolet absorbers, other resins, plasticizers, heat stabilizers, antioxidants, light stabilizers, crystal nucleating agents, antiblocking agents, sealability improvers, mold release agents, colorants, pigments, foaming agents, flame retardants, and the like, as long as the laminated film satisfies the properties described below.

[0045] The thickness (T2) of the AC resin film is preferably 25 μm or more and 200 μm or less, more preferably 35 μm or more and 150 μm or less, and even more preferably 40 μm or more and 100 μm or less. When the thickness is 25 μm or more, the hardness of the laminated film can be sufficiently increased. When the thickness is 200 μm or less, the formability, stretchability, and transparency of the laminated film can be improved.

[0046] (Laminated film) The laminated film is made by laminating an AC resin film and a VDF resin film in contact with each other, and by appropriately controlling the microstructure of the VDF resin in the VDF resin film, the hardness of the VDF resin film is maintained while the tensile modulus is lowered and the elongation at break is increased, thereby improving the stretchability.

[0047] The laminate film is attached to the surface of a preformed substrate by methods such as vacuum forming or pressure forming, while being heated and stretched. The laminate film has high stretchability, making it easy to attach to the surface shape of the substrate. Furthermore, despite its high stretchability, the laminate film also has high hardness, resulting in high scratch resistance after stretching. Furthermore, despite being laminated with an AC-based resin film, the transparency of the VDF-based resin film is not easily reduced even after stretching, so the laminate film maintains high transparency even after stretching. Furthermore, since the VDF-based resin film contains almost no AC resin, the laminate film also has high chemical resistance after attachment.

[0048] Specifically, the haze of the laminated film, measured in an unstretched state according to JIS K 7136: 2000 (ISO 14782: 1999), is 10% or more and 50% or less, preferably 20% or more and 40% or less, more preferably 20% or more and 35% or less, and even more preferably 25% or more and 35% or less.

[0049] Furthermore, the 60° gloss value of the VDF resin layer side of the laminated film, measured in an unstretched state in accordance with JIS Z 8741:1997, is 10% or more and 60% or less, preferably 20% or more and 50% or less, more preferably 20% or more and 40% or less, and even more preferably 30% or more and 40% or less.

[0050] Furthermore, the laminated film has a breaking elongation at 23°C measured in an unstretched state in accordance with JIS K 7161-1:2014 (ISO 527-1:2012) of preferably 100% or more and 400% or less, more preferably 130% or more and 300% or less, even more preferably 130% or more and 200% or less, and particularly preferably 130% or more and 180% or less.

[0051] Furthermore, the scratch hardness (pencil method) of the laminate film, measured in an unstretched state in accordance with ISO 15184:2020 for VDF-based resin films, is preferably HB or more and 6H or less, more preferably HB or more and 2H or less, and even more preferably HB or more and F or less. By sufficiently increasing the hardness in an unstretched state, the scratch resistance after stretching can also be improved.

[0052] Furthermore, the laminated film has a tensile modulus at 23°C measured in an unstretched state in accordance with JIS K 7161-1:2014 (ISO 527-1:2012) of 500 MPa or more and 1500 MPa or less, preferably 800 MPa or more and 1400 MPa or less, and more preferably 1000 MPa or more and 1350 MPa or less.

[0053] Furthermore, the ratio (T1 / T2) of the thickness of the VDF resin film (T1) to the thickness of the AC resin film (T2) of the laminate film is preferably 1 / 20 or more and 1 / 4 or less, more preferably 1 / 18 or more and 1 / 5 or less, even more preferably 1 / 15 or more and 1 / 8 or less, and particularly preferably 1 / 12 or more and 1 / 9 or less. Increasing T1 / T2 (increasing the proportion of the VDF resin film thickness) can improve the chemical resistance of the laminate film. Decreasing T1 / T2 (increasing the proportion of the AC resin film thickness) can improve the abrasion resistance of the laminate film.

[0054] The thicknesses T1 and T2 are values ​​measured by observing the cross section of the laminated film cut with a single-edged knife perpendicular to the thickness direction so as to have a smooth cross section.

[0055] The laminated film has a haze, measured according to JIS K 7136:2000 (ISO 14782:1999) when stretched to 140% at 120°C, of ​​10% to 50%, preferably 20% to 50%, more preferably 20% to 40%, even more preferably 25% to 40%, and particularly preferably 30% to 40%.

[0056] Furthermore, the laminate film, when stretched to 140% at 120°C, has a 60° gloss value on the VDF resin layer side, measured in accordance with JIS Z 8741:1997, of 10% or more and 60% or less, preferably 20% or more and 50% or less, more preferably 20% or more and 40% or less, and particularly preferably 30% or more and 40% or less.

[0057] The stretching direction may be either the MD or TD direction of the laminated film. In this embodiment, it is sufficient that the haze and 60° gloss value are within the above ranges when the laminated film is stretched to 140% at 120°C in at least one of the MD and TD directions.

[0058] [Laminated film manufacturing method] The method for producing the laminated film is not particularly limited, but a method in which a heat-molten AC resin film material and a heat-molten VDF resin film material are co-extruded and then cooled is preferred.

[0059] Specifically, the VDF resin is heated, melted, and kneaded in the first extruder. If the VDF resin film contains additives such as a matting agent or alkyl quaternary ammonium sulfate, these additives are also kneaded together with the VDF resin in the first extruder.

[0060] The heating temperature (cylinder temperature) in the first kneader is preferably 210°C or higher and 260°C or lower, and more preferably 210°C or higher and 240°C or lower. By setting the heating temperature to 210°C or higher, the VDF-based resin can be melted and thoroughly kneaded. By setting the heating temperature to 260°C or lower, yellowing and deterioration of transparency due to decomposition of alkyl quaternary ammonium sulfate and the like can be suppressed.

[0061] At the same time, the AC resin is heated and melted in the second extruder and kneaded. If the AC resin film contains additives, the additives are also kneaded together with the AC resin in the second extruder.

[0062] The heating temperature (cylinder temperature) in the second kneader is preferably 200°C or higher and 260°C or lower, and more preferably 200°C or higher and 240°C or lower. By setting the heating temperature to 200°C or higher, the AC-based resin can be melted and thoroughly kneaded. By setting the heating temperature to 260°C or lower, yellowing and deterioration of transparency due to decomposition of the AC-based resin and additives can be suppressed.

[0063] The melt-kneaded VDF resin and AC resin are then co-extruded through a feedblock T-die or multi-manifold T-die connected to the first and second extruders, resulting in a molten extrudate in which the VDF resin and AC resin are laminated.

[0064] The molten extrudate is then cooled by contacting it with a cooling roll while maintaining a temperature of 150°C or higher. The cooling roll can be a metallic mirror-finish touch roll or a metallic endless belt. The surface temperature of the cooling roll is preferably 125°C or lower, more preferably 30°C to 100°C. The VDF resin side of the molten extrudate is preferably brought into contact with the cooling roll. Rapid cooling of the VDF resin by contacting it with a cooling roll set at a relatively low temperature appropriately suppresses crystallization of the VDF resin, appropriately controls the crystalline structure of the VDF resin, and reduces the tensile modulus and increases the elongation at break while maintaining the hardness of the VDF resin film. The molten extrudate before cooling and solidifying may be brought into contact with a matte roll to further adjust the gloss value.

[0065] The laminated film that has been cooled and solidified can be wound into a roll for storage, transportation, and the like.

[0066] [Application] The laminated film described above can be used as a decorative film to be attached by vacuum forming or pressure forming to the surface of an interior or exterior substrate of an automobile, railcar, aircraft, ship, spacecraft, home appliance, furniture, building, etc. When attaching, the VDF-based resin film is attached to the surface of the substrate so that the VDF-based resin film side faces outward.

[0067] [Other embodiments] It should be noted that the above-described embodiments are exemplary embodiments of the present invention, and it goes without saying that the present invention may include embodiments other than the above-described embodiments within the scope of its core technical concept. [Example]

[0068] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0069] 1. Preparation of laminated film To 100 parts by mass of a VDF homopolymer having an inherent viscosity of 0.85 dl / g, 3.0 parts by mass of a matting agent (Eposter MV1004, manufactured by Nippon Shokubai Co., Ltd.) was added. The VDF homopolymer to which the matting agent had been added was melt-kneaded at a cylinder temperature of 190°C using a co-rotating twin-screw extruder (TEM-26, manufactured by Shibaura Machine Co., Ltd.) to obtain a pelletized VDF resin composition 1.

[0070] VDF-based resin compositions were obtained in the same manner by varying the inherent viscosity of the VDF-based polymer, the presence or absence and ratio of copolymerization with hexafluoropropylene (hereinafter abbreviated as "HFP"), the amount of matting agent, and the presence or absence and amount of addition of tetrabutylammonium hydrogen sulfate (manufactured by Koei Chemical Industry Co., Ltd., hereinafter abbreviated as "TBAHS").

[0071] The VDF-based resin composition 1 obtained above was thermally melted in a φ30 mm first extruder with a cylinder temperature set to 240°C. Furthermore, a methacrylic resin (Parapet GR-F, manufactured by Kuraray Co., Ltd.) was thermally melted in a φ30 mm second extruder with a cylinder temperature set to 240°C. The thermally melted VDF-based resin composition and methacrylic resin were then co-extruded from a multi-manifold T-die connected to the first and second extruders. The VDF-based resin composition side was then brought into contact with a cooling roll whose surface was set to 98°C for cooling, yielding a laminated film 1 consisting of a 5 μm-thick VDF-based resin layer and a 45 μm-thick methacrylic resin layer (hereinafter abbreviated as "AC layer").

[0072] Laminated films 2 to 13 were obtained in the same manner except that the type of VDF resin composition and the thickness of each layer were changed.

[0073] 90 parts by weight of a VDF homopolymer with an inherent viscosity of 1.00 dl / g, 10 parts by weight of a methacrylic resin (Parapet GR-F, manufactured by Kuraray Co., Ltd.), and 3.0 parts by weight of a matting agent (Eposter MV1004, manufactured by Nippon Shokubai Co., Ltd.) were premixed in an unmelted state. This mixture was melt-kneaded at a cylinder temperature of 190°C in a co-rotating twin-screw extruder (TEM-26, manufactured by Shibaura Machine Co., Ltd.) to obtain a pelletized VDF-based resin composition. Laminated film 14 was obtained in the same manner as laminated film 1, except that this VDF-based resin composition was used.

[0074] Laminated film 15 was obtained in the same manner as in the production of laminated film 14, except that the VDF homopolymer was 80% by mass and the methacrylic resin was 20% by mass.

[0075] The inherent viscosity of the VDF resin was measured in accordance with JIS K 7367-1:2002. Specifically, 80 mg of the VDF resin was dissolved in 20 ml of N,N-dimethylformamide, and the viscosity η of the polymer solution was measured using an Ubbelohde viscometer in a thermostatic bath at 30°C. The viscosity η of the polymer solution and the viscosity η of N,N-dimethylformamide used as the solvent were then calculated. oBased on the solution concentration C (g / dl), the inherent viscosity η is calculated using the following formula: i asked for. η i =(1 / C)·ln(η / η o ) Here, the concentration of the solution is 0.4 g / dl.

[0076] 2. Evaluation of laminated film (before stretching) The obtained laminated film was evaluated as follows without being stretched.

[0077] 2-1.Thickness The laminate film was cut perpendicular to the thickness direction using a single-edged knife so that the cross section was smooth. The film cross section was observed at 800x magnification using a digital microscope (Keyence Corporation, VHX-700F) to measure the thicknesses of the VDF-based resin layer and the AC-based resin layer, and the thickness of the VDF-based resin layer (T1) and the thickness of the AC layer (T2) were measured. The thickness was measured at a total of five points: a measurement point set in the center of the laminate film and four other points set at least 50 mm away from the other measurement points, and the average of these measurements was used as the thickness of each layer in the laminate film.

[0078] 2-2. Hayes The haze of the laminated film was measured using a haze meter (NDH4000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 7136: 2000 (ISO 14782: 1999). Haze measurements were taken at a total of five locations: a measurement point set at the center of the laminated film and four other locations arbitrarily set at least 50 mm away from the other measurement points, and the average of these measurements was taken as the haze of the laminated film.

[0079] 2-3.60° gloss value Using a glossmeter (IG-331, manufactured by Horiba, Ltd.), the 60° gloss value of the VDF-based resin layer side of the laminate film was measured in accordance with JIS Z 8741: 1997. Gloss values ​​were measured at an incident / reflection angle of 60° at a total of five locations: a measurement point set at the center of the laminate film and four other locations arbitrarily set at least 50 mm away from the other measurement points, and the average of these measurements was taken as the 60° gloss value of the laminate film.

[0080] 2-4. Breaking elongation Tensile tests were conducted in accordance with JIS K 7161-1:2014 (ISO 527-1:2012) to measure the elongation at break using a universal testing machine (Shimadzu Corporation, Autograph AGS-J) at a temperature of 23°C and a tensile speed of 50 mm / min.

[0081] 3. Evaluation of laminated film (after stretching) The obtained laminated film was stretched by 140% at 120° C. The laminated film after stretching was evaluated as follows.

[0082] 3-1. Hayes The haze was measured in the same manner as for the laminated film before stretching.

[0083] 3-2.60° gloss value The 60° gloss value was measured in the same manner as for the laminated film before stretching.

[0084] 3-3.Chemical resistance A small amount of sunscreen cream (Neutrogena UltraSheer SPF45, manufactured by Johnson & Johnson) was applied to the VDF resin film side of the laminated film, the applied area was covered with a cover glass, and the film was left to stand at 80°C for 1 hour. After leaving the film to stand, the adhering sunscreen cream was wiped off, the film was washed with water, and the appearance of the applied area was evaluated according to the following evaluation criteria. ○ No change in appearance is observed. △: Minor application marks or minor wrinkles are observed. × Whitening or obvious deterioration of the surface is observed.

[0085] 4.Results Table 1 shows the preparation conditions and evaluation results of each laminated film.

[0086] [Table 1]

[0087] [Reference example] To 100 parts by mass of a VDF homopolymer having an inherent viscosity of 1.00 dl / g, 3 parts by mass of a matting agent were added, and without adding TBAHS, the mixture was melt-kneaded at a cylinder temperature of 190°C using a co-rotating twin-screw extruder (Shibaura Machine Co., Ltd., TEM-26) to obtain a pelletized VDF-based resin composition.

[0088] The VDF-based resin composition obtained above was heat-melted in a φ30 mm extruder with a cylinder temperature set to 240°C, extruded from a T-die connected to the extruder, and cooled by contacting the surface with a cooling roll set to 98°C, to obtain a single-layer film consisting of a 40 μm-thick VDF-based resin layer.

[0089] The haze of the obtained monolayer film was measured before and after stretching in the same manner as for the laminated film. The haze before stretching was 72% and the haze after stretching was 61%.

[0090] The results of Comparative Examples 10 to 13 and Reference Examples show that, although the haze of a VDF resin film containing a matting agent is usually reduced when stretched while heated, the haze increases when laminated with an AC resin film and stretched while heated. In contrast, the results of Examples 1 to 9 show that by appropriately controlling the microstructure by adding TBAHS or copolymerizing with HFP, the haze does not increase even when stretched while heated. [Industrial Applicability]

[0091] The laminated film of the present invention maintains the good transparency of the VDF-based resin film and low gloss even after heat stretching, making it suitable for use as a matte film for pressure forming or vacuum forming.

Claims

1. A laminated film in which an acrylic resin film and a vinylidene fluoride resin film are laminated, The 60° gloss value measured in an unstretched state is 10% or more and 60% or less, and the haze is 10% or more and 50% or less, When stretched 140% at 120°C, the 60° gloss value is 10% or more and 60% or less, and the haze is 10% or more and 50% or less. Decorative laminated film.

2. The breaking elongation at 23°C is 100% or more and 400% or less. The decorative laminate film according to claim 1 .

3. The vinylidene fluoride resin film has a thickness (T1) of 1 μm or more and 30 μm or less. The decorative laminate film according to claim 1 .

4. The vinylidene fluoride resin film contains a vinylidene fluoride resin having an inherent viscosity of 0.80 dL / g or more and 1.20 dL / g or less. The decorative laminate film according to claim 1 .

5. The vinylidene fluoride resin film contains a vinylidene fluoride resin and a matting agent in an amount of 1.0 parts by mass or more and 20.0 parts by mass or less per 100 parts by mass of the vinylidene fluoride resin. The decorative laminate film according to claim 1 .

6. The vinylidene fluoride resin film contains a vinylidene fluoride resin and 0.3 parts by mass or more and 5.0 parts by mass or less of an alkyl quaternary ammonium sulfate relative to 100 parts by mass of the vinylidene fluoride resin. The decorative laminate film according to claim 1 .

7. The vinylidene fluoride resin film contains a vinylidene fluoride copolymer having a content of structural units derived from hexafluoropropylene of 1.0% by mass or more and 5.0% by mass or less. The decorative laminate film according to claim 1 .

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