Layered film, laminate using same, and display member or packaging material including said laminate

Abstract

This layered film includes a substrate resin and a resin layer (X) on at least one side of the substrate resin. The resin layer (X) has the following characteristics: (1) The surface free energy of the resin layer (X) is at least 42.5 mN / m and no greater than 55.0 mN / m; and (2) When a water-based hard coating layer is further provided over the resin layer (X), the adhesiveness, according to the cross-cut method, after 24 hours of boiling is at least 60 / 100. Provided are: a layered film with excellent adhesiveness, in a moist environment, to a processed layer formed from a water-based paint; a laminate using the layered film; and a display member or packaging material that includes the laminate.

Description

Laminated film, laminate using same, and display member or packaging material including said laminate

[0001] The present invention relates to a laminate film that has excellent adhesion to a processing layer even in a humid environment, a laminate using the same, and a display member or packaging material that includes the laminate.

[0002] Thermoplastic resin films, particularly polyester films, have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance, and are therefore widely used in magnetic recording materials, packaging materials, optical films such as antireflection films, diffusion sheets, and prism sheets used in flat displays, etc., transparent touch panels, etc. However, when other materials are coated and laminated onto the polyester film to form a layer having a desired function in order to suitably use it for these applications, there is a drawback in that adhesion is poor depending on the material used.

[0003] Therefore, one method for imparting adhesiveness to the surface of a polyester film is known, which involves applying various resins to the surface of the polyester film to form a coating layer (adhesive layer) with adhesive properties. A specific example is a method for improving adhesiveness by forming a coating layer on the surface of a polyester film, which comprises a polyurethane copolymer resin layer on the surface (Patent Document 1). Furthermore, the adhesiveness between the adhesive layer and various resin-processed layers is known to change depending on factors such as the passage of time and storage conditions. An example of an adhesive layer with better durability is a laminated film having a resin layer containing at least metal oxide particles (A) having a number-average particle diameter of 3 nm to 50 nm and a polyester resin (B) containing naphthalenedicarboxylic acid as an acid component (Patent Document 2).

[0004] On the other hand, in recent years, when various functional materials are coated and laminated onto polyester films, water-based coating materials that use water as the main solvent or dispersion medium and reduce organic solvents are often used to reduce the environmental impact. The problem with such water-based coating materials is that the conventional easy-adhesion layer described above does not provide sufficient adhesion.

[0005] As an easy-adhesion layer that improves adhesion to such water-based coating materials, a laminate film having a resin layer (X) on at least one surface, in which the surface zeta potential of the resin layer (X) is -20 mV or more and less than 0 mV, and a laminate polyester film having a resin layer (X) on the outermost surface of at least one side of a polyester substrate, in which the ratio (γh / γd) of the dispersion force (γd) to the hydrogen bonding force (γh) in the surface free energy of the resin layer (X) is 0.250 or less (Patent Document 3, Patent Document 4).

[0006] JP 2001-191673 A JP 2015-180524 A JP 2017-149005 A International Publication No. 2023 / 042576

[0007] First, the inventors of the present invention verified the adhesion of the technologies of Patent Documents 1 and 2 to water-based coating materials, and found that it is difficult to control the adhesion to water-based paints simply by changing the functional groups, molecular weight, main chain structure, etc. of the polyurethane resin or polyester resin, and that even when the same polyester resin is used, the adhesion may change depending on the manufacturing conditions, making it difficult to stably obtain sufficient adhesion. In particular, when the resin layer described in Patent Document 2 is applied to a water-based coating material, it has become clear that the adhesion is insufficient during long-term storage due to deterioration of the coating layer itself formed by the water-based coating material when stored in a humid environment.

[0008] On the other hand, when the technologies of Patent Document 3 and Patent Document 4 were examined, it was found that although a certain effect was observed in terms of the initial adhesion of the water-based coating material, the design of the present invention described below did not take into account the adhesion to the processed layer in a humid environment, and it was confirmed that the adhesion of both technologies deteriorated during long-term storage.

[0009] Therefore, the present invention aims to overcome the above drawbacks and provide a laminate film that has excellent adhesion to a processing layer even in a humid environment, a laminate using the same, and a display member or packaging material that includes the laminate.

[0010] The present invention comprises the following configurations.

[0011] [1] A laminated film having a base resin and a resin layer (X) on at least one side of the base resin, wherein the resin layer (X) satisfies the following characteristics: (1) The surface free energy of the resin layer (X) is 42.5 mN / m or more and 55.0 mN / m or less. (2) When an aqueous hard coat layer is further provided on the resin layer (X), the adhesion after boiling for 24 hours is 60 / 100 or more as measured by a cross-cut method.

[0012] [2] A laminated film having a base resin and a resin layer (X) on at least one surface of the base resin, wherein the resin layer (X) satisfies the following characteristics: (1) The surface free energy of the resin layer (X) is 42.5 mN / m or more and 55.0 mN / m or less. (2) The resin layer (X) contains one or more compounds (A) selected from the group consisting of alkylene glycol, acetylene glycol, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

[0013] [3] The laminate film according to [2], which further satisfies the following characteristics: (1) When an aqueous hard coat layer is further provided on the resin layer (X), the adhesiveness after boiling for 24 hours by the cross-cut method is 60 / 100 or more.

[0014] [4] The laminate film according to any one of [1] to [3], wherein the resin layer (X) has a water swelling rate of 10 wt % or less. Water swelling rate (%): a value calculated by dividing the mass of the resin layer (X) after leaving it in an atmosphere of room temperature (23°C) and relative humidity (65%) for 24 hours, the moisture content of the resin layer (X) obtained by heating it from room temperature to 120°C at a rate of 10°C / min and analyzing and integrating the concentration of water generated from the resin layer (X) during heating, and the moisture content by the mass of the sample after the heating treatment (i.e., the mass of the resin layer (X) from which moisture has been removed).

[0015] [5] In the peak intensity F detected by time-of-flight secondary ion mass spectrometry on the surface of the resin layer (X), the peak intensity of the fragment of the negative ion exhibiting the maximum intensity is defined as M, and the negative ion (F) derived from elemental fluorine １７- 5. The laminated film according to any one of [1] to [4], wherein Ff / M is less than 0.010, where Ff is the peak intensity of the peak intensity of the tensile strength ...

[0016] [6] Among the peak intensities F detected by time-of-flight secondary ion mass spectrometry on the surface of the resin layer (X), the peak intensity M of a positive ion fragment exhibiting the maximum intensity is ＋ or the peak intensity M of the negative ion fragment showing the maximum intensity － [6] The laminated film according to any one of [1] to [5], wherein Fh / M is 0.001 or more and 0.500 or less, where M is the maximum peak intensity and Fh is the total peak intensity of the fragments derived from the compound (A).

[0017] [7] The laminated film according to any one of [1] to [6], wherein the resin layer (X) has a PFAS (perfluoroalkyl and polyfluoroalkyl substances) content of 50 ppm or less.

[0018] [8] The laminated film according to any one of [1] to [7], wherein the compound (A) is a surfactant having an HLB value of 10 or more and 18 or less.

[0019] [9] The laminate film according to any one of [1] to [8], wherein the resin layer (X) contains a polyester resin (B) that satisfies the following characteristics: (B-1) contains at least a sulfo group in a side chain, and (B-2) has a conjugated cyclic structure in a main chain.

[0020]

[10] The laminate film according to any one of [1] to [9], wherein the resin layer (X) contains at least one compound (C) selected from an acrylic resin, a urethane resin, an epoxy resin, an oxazoline compound, and a carbodiimide compound.

[0021]

[11] The laminated film according to any one of [1] to

[10] , wherein the base resin contains at least one of a biomass raw material and a recycled raw material.

[0022]

[12] The laminate film according to any one of [1] to

[11] above, which is used as a display film or a packaging film.

[0023]

[13] The laminate film according to any one of [1] to

[12] , wherein at least one of the resin layers (X) has a processing layer (Y) on the surface opposite to the surface having the base resin. The processing layer (Y) contains at least one of a hard coating agent, a pressure-sensitive adhesive, and a printing ink.

[0024]

[14] A display member or packaging material comprising the laminate according to

[13] above.

[0025] According to the present invention, it is possible to provide a laminate film that has excellent adhesion in a humid environment, particularly with a processing layer formed from a water-based coating material, a laminate using the same, and a display component or packaging material that includes the laminate.

[0026] Hereinafter, the solution or dispersion used to form the resin layer (X) of the present invention will be referred to as a "coating composition," and the solution or dispersion applied to form a layer having the desired function on the resin layer (X) of the laminated film of the present invention will be referred to as an "aqueous coating material."

[0027] Water-based coating materials generally have better environmental compatibility than organic solvent-based coating materials. However, because the resin used to stabilize the coating material is easily absorbed by water, the resulting processed layer tends to lack water resistance, and there is a problem that adhesion is easily reduced due to water penetration, especially in humid environments. As a result of studying such problems, the present inventors have found that by forming a resin layer with specific functions on the base resin, the adhesion of the processed layer formed with the water-based coating material can be improved.

[0028] That is, in a first aspect of the present invention, a laminated film having a base resin and a resin layer (X) on at least one side of the base resin, wherein the surface free energy of the resin layer (X) is 42.5 mN / m or more and 55.0 mN / m or less, and when an aqueous hard coat layer is further provided on the resin layer (X), the adhesion after boiling for 24 hours by the cross-cut method is 60 / 100 or more, thereby maintaining good adhesion of the processed layer formed by the aqueous coating material. Details are explained below. Note that, unless otherwise specified, the numerical range specified in the present invention means the value obtained by rounding off the value to one digit below the stated number.

[0029] First, the surface free energy of the resin layer (X) is a parameter that contributes to the application and adhesion of the water-based coating material to the resin layer (X); when the surface free energy is less than 42.5mN / m, compared with when the resin layer is covered with the water-based coating material, the resin layer (X) with lower energy is more likely to be exposed to the surface, and as a result, it becomes difficult to carry out uniform application.On the other hand, as for the upper limit, it has been thought that the higher the numerical value, the better the adhesion; but the inventors have verified that when the surface free energy is more than 55.0mN / m, water penetration into the processing layer and the resin layer (X) after processing with the water-based coating material is likely to occur, and therefore, it has been found that this is unfavorable to the adhesion under humid conditions.

[0030] Furthermore, there is a preferred range for the surface free energy of the resin layer (X) to further improve adhesion.Specifically, 48.0 mN / m or more and 55.0 mN / m or less is more preferred, and 49.0 mN / m or more and 52.0 mN / m or more is particularly preferred.In addition, the method for controlling the surface free energy of the resin layer (X) will be described later, but it can be controlled by the constituent components, manufacturing method and their combination.Specifically, it is possible to adjust the wettability to water-based coating materials by the functional group species having the constituent resin or compound in the side chain, the molecular weight of the unit structure when using a polymer, the progress of the crosslinking reaction, etc.Details of preferred constituent materials and manufacturing method will be described later.

[0031] Next, the adhesiveness after boiling for 24 hours by the cross-cut method when a water-based hard coat layer is further provided on the resin layer (X) will be described.Patent document 3 describes boiling adhesiveness as an index for designing the adhesiveness of the resin layer, but when evaluating the adhesiveness of the processed layer formed by the water-based coating material, it is necessary to use an index that takes into account the water resistance of the processed layer.

[0032] As a result of the inventors' investigations, the preferred aqueous hard coating for the processing layer was an acrylate derived from dipentaerythritol. Dipentaerythritol is a polyhydric alcohol having six hydroxyl groups in its molecular structure, and a multifunctional acrylate can be obtained by dehydration condensation of acrylic acid with the hydroxyl groups. In order to impart excellent hard coating properties such as scratch resistance to the processing layer, it is preferable to increase the crosslink density using a multifunctional acrylate. Furthermore, when preparing a hard coating agent as an aqueous coating material, it is preferable because the hydrophilicity / hydrophobicity of the hard coating layer can be easily adjusted by the aforementioned hydroxyl group / acrylate substitution ratio. To achieve both the scratch resistance of dipentaerythritol and the ability to be used as an aqueous coating material, a method of mixing materials with different hydroxyl group / acrylate substitution ratios is exemplified, and a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate is particularly preferred. Examples of commercially available acrylates using dipentaerythritol as a starting material include "Aronix" (registered trademark) from Toagosei Chemical Co., Ltd., "Light Acrylate" (registered trademark) from Kyoeisha Chemical Co., Ltd., "NK Ester" (registered trademark) from Shin-Nakamura Chemical Co., Ltd., and "EBECRYL" (registered trademark) from Daicel-Allnex Co., Ltd. Details of a method for preparing an aqueous hard coating agent using an acrylate using dipentaerythritol as a starting material will be described later.

[0033] Using the above-mentioned aqueous hard coat, the design index of a resin layer (X) that can withstand practical use was investigated. As a result, it was confirmed that a resin layer (X) that can maintain an adhesion of 60 / 100 or more by the cross-cut method after 24 hours of boiling can maintain sufficient adhesion in a humid environment in actual use. When an aqueous hard coat layer is provided, the adhesion after 24 hours of boiling by the cross-cut method must be 60 / 100 or more, preferably 80 / 100 or more, and particularly preferably 95 / 100 or more. The upper limit is 100 / 100. A method for controlling the adhesion after 24 hours of boiling by the cross-cut method when an aqueous hard coat layer is provided will be described later. This can be controlled by the constituent components, manufacturing method, and their combinations. A particularly preferred method is to specifically control the adhesion by designing using the compound (A) described later. Details of preferred constituent materials and manufacturing methods will be described later.

[0034] Furthermore, the present inventors have discovered a second aspect of a specific material that can effectively control the aforementioned "adhesion after 24 hours of boiling by the cross-cut method when an aqueous hard coat layer is provided." That is, a laminated film having a base resin and a resin layer (X) on at least one side of the base resin, wherein the surface free energy of the resin layer (X) is 42.5 mN / m or more and 55.0 mN / m or less, and the resin layer (X) contains one or more compounds (A) from the group consisting of alkylene glycol, acetylene glycol, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. It has been found that the adhesion stability of the processed layer formed by the aqueous coating material in a humid environment is improved. Since the surface free energy of the resin layer (X) is the same as that described above, details of compound (A) are described below.

[0035] Compound (A) is a material corresponding to the surfactant described below, and when the resin layer (X) is formed by coating using a coating composition, which is a preferred production method, it is a material that can be blended as an additive in the coating composition. Conventionally, in a resin layer formed on a resin substrate to impart adhesion, its wettability and adhesion have generally been controlled by adjusting the resin component, which is the main constituent (matrix material), or the skeleton of the crosslinking agent, which is a reactive component that imparts film-forming properties to the coating film, or the amount of the coating composition. However, as a result of investigations by the present inventors, it has been found that the adhesion of a processed layer formed with a water-based coating material in a humid environment is significantly affected by the surfactant (compound (A)) remaining between the processed layer and the resin layer.

[0036] The influence of compound (A) on adhesion can be broadly divided into the following two types of factors. The first factor corresponds to the affinity of the resin, and it was confirmed that adhesion decreases when the constituent materials are significantly different from the resin layer (X) or the processed layer formed with a water-based coating material. Details of the materials that contribute to the decrease in adhesion will be described later. On the other hand, the second factor corresponds to compatibility with water. As mentioned above, since the processed layer using a water-based coating material is, in principle, compatible with water, it was confirmed that adhesion also tends to decrease when the surfactant has a certain level of hydrophilicity. Details of preferred material design will be described later.

[0037] Methods for confirming that the resin layer (X) contains the compound (A) include a method of analyzing the resin layer (X) and a method of analyzing the coating composition used to produce the resin layer (X). The presence or absence of the compound (A) can be determined by subjecting components extracted from the resin layer (X) to any organic chemical analysis.

[0038] As an example of the analytical method, for example, the formed resin layer (X) is collected as about 2 g of powder by the method described below, placed in a stoppered Erlenmeyer flask, 20 mL of methanol precisely measured with a volumetric pipette is added, the flask is stopped up, and the mixture is subjected to thermal extraction in a water bath at 60°C for 1 hour. The obtained extract is subjected to gas chromatography, and the presence or absence of the compound (A) can be calculated in parts per million by mass (ppm) from the mass value of the extract.

[0039] Preferred embodiments of the laminated film of the present invention will be described in detail below.

[0040] <Laminated Film, Substrate Resin> The laminated film of the present invention has a resin layer (X) on at least one side of the substrate resin. In the laminated film of the present invention, the substrate resin is preferably a thermoplastic resin, which is a general term for films that melt or soften when heated. Examples of thermoplastic resins include polyester resins, polypropylene resins, polyethylene film and other polyolefin resins, polylactic acid resins, polycarbonate resins, acrylic resins such as polymethacrylate resins and polystyrene resins, nylon resin and other polyamide resins, polyvinyl chloride resins, polyurethane resins, fluororesins, polyphenylene resins, etc. The thermoplastic resin used in the thermoplastic resin film may be a homopolymer or a copolymer. Furthermore, multiple resins may be used.

[0041] Representative examples of thermoplastic resin films using these thermoplastic resins include polyester films, polyolefin films such as polypropylene films and polyethylene films, polylactic acid films, polycarbonate films, acrylic films such as polymethacrylate films and polystyrene films, polyamide films such as nylon, polyvinyl chloride films, polyurethane films, fluorine-based films, and polyphenylene sulfide films.

[0042] The thermoplastic resin film in the present invention is not particularly limited, but polyester films and polyethylene films, which are excellent in mechanical strength and processability, are preferred. In particular, polyester films are preferred in terms of heat resistance and mechanical properties (hereinafter, the polyester film used as the resin substrate may be referred to as the "substrate film" or "substrate").

[0043] Here, polyester is a general term for polymers in which an ester bond is the main bonding chain of the main chain, and those containing at least one component selected from ethylene terephthalate, propylene terephthalate, ethylene-2,6-naphthalate, butylene terephthalate, propylene-2,6-naphthalate, ethylene-α,β-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylate, etc. as a main component can be preferably used.

[0044] Here, the term "major component" refers to a component unit that is contained in an amount of more than 50 mol% but not more than 100 mol% when all the component units constituting the resin are taken as 100 mol%. It is preferable that the component unit contained in the major component is more than 70 mol%. Furthermore, the term "laminated polyester film" refers to a sheet-like material having at least two layers and containing polyester as the main component. The term "major component" refers to a component that is contained in an amount of more than 50 mass% but not more than 100 mass% of all the components. The term "polyester substrate" refers to a sheet-like material that constitutes the laminated polyester film and that is mainly composed of polyester. Furthermore, the above-mentioned polyester can contain 30 mol% or less of a copolymer component in all the components, if necessary.

[0045] As the polyester substrate, which is a preferred base resin in the laminate film of the present invention, a polyethylene terephthalate film is preferably used from the viewpoints of heat resistance and smoothness. Furthermore, when the laminated polyester film is subjected to heat or shrinkage stress, a polyethylene-2,6-naphthalate film, which has excellent heat resistance and rigidity, is preferably used. Here, a polyethylene terephthalate film refers to a film in which polyethylene terephthalate (including copolymers) accounts for more than 50% by mass and not more than 100% by mass of all components constituting the film, and the same can be said for a polyethylene-2,6-naphthalate film.

[0046] From the viewpoints of thermal stability and mechanical strength, the polyester substrate is preferably biaxially oriented. A biaxially oriented polyester film is a polyester film that exhibits a pattern of orientation along two orthogonal axes in wide-angle X-ray diffraction. Generally, biaxially oriented polyester films are obtained by stretching an unstretched polyester sheet in two orthogonal directions. For example, the film is stretched approximately 2.5 to 5.0 times in each of the longitudinal and width directions, and then heat-treated to complete the crystal orientation. Using a biaxially oriented polyester film as the polyester substrate improves the thermal stability, particularly the dimensional stability and mechanical strength, of the laminated polyester film, as well as its flatness. Here, the longitudinal direction refers to the direction in which the film runs during the manufacturing process (equivalent to the winding direction of the film in a film roll), and the width direction refers to the direction perpendicular to the longitudinal direction within the film plane.

[0047] The polyester substrate may also contain various additives, such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, and nucleating agents, to the extent that they do not deteriorate the properties of the polyester substrate.

[0048] The thickness of the polyester substrate is not particularly limited and may be appropriately selected depending on the application and type, but is usually preferably 10 to 500 μm, more preferably 20 to 250 μm, and particularly preferably 30 to 150 μm, from the viewpoints of mechanical strength, handleability, etc. The polyester substrate may be a composite film obtained by coextrusion, or may be a film obtained by laminating obtained films by various methods.

[0049] The laminate film of the present invention preferably has a total light transmittance of 88% or more, more preferably 90% or more. Since the laminate film has a total light transmittance of 88% or more, it can be suitably used as an optical film such as a display film. Furthermore, since the upper limit of the substantial total light transmittance of industrially usable base resins is 94%, it is preferable that the total light transmittance be 88% or more but less than 94%.

[0050] The total light transmittance of the laminate film can be measured using a measuring device in accordance with JIS "Determination of Haze of Transparent Materials" (K7136, 2000 edition). Methods for making the total light transmittance of the laminate film 88% or more include, for example, improving the flatness by the above-mentioned biaxial stretching, and forming a smooth coating layer on the outermost surface of the laminate film to reduce the reflectance with the air layer.

[0051] Furthermore, the laminate film of the present invention preferably has a haze value of 3.0% or less, and particularly preferably 1.0% or less. By setting the haze value of the laminate film within the above range, transparency is increased, making it suitable for use in optical films that require transparency. The lower the haze value, the more preferable it is, and there is no particular lower limit, but from the perspective of feasibility, the lower limit is 0.01%. The haze value is also sometimes called "haze."

[0052] The haze value of the laminated film can be measured by a method conforming to JIS "Method for Determining Haze of Transparent Materials" (K7136 2000 edition), and details thereof are shown in the Examples. Furthermore, examples of a method for adjusting the haze value of the laminated polyester film to a suitable range include a method for reducing the reflection and scattering of light at the interface with air by adjusting the surface shape and refractive index of a coating layer formed on the outermost surface of the base resin.

[0053] <Biomass raw materials and recycled raw materials> The polyester base material, which is a particularly preferred base resin for the laminated film of the present invention, preferably contains at least one of biomass raw materials and recycled raw materials from the viewpoint of reducing environmental impact. Here, biomass refers to organic compounds photosynthesized from carbon dioxide and water. When biomass is burned, it usually becomes carbon dioxide and water again, so biomass can be used as so-called carbon-neutral renewable energy.

[0054] When the biomass degree is defined as the ratio of plant-derived carbon atoms to the total carbon atoms, for example, in an ethylene terephthalate unit, if only the ethylene glycol component is entirely plant-derived, the biomass degree is theoretically 20%. To increase the biomass degree beyond that, the terephthalic acid must also be plant-derived, which would increase the environmental impact reduction effect but would increase production costs. The ethylene glycol component and the terephthalic acid component may be a combination of petroleum-derived and plant-derived components. From the viewpoint of achieving an environmental impact reduction effect, the lower limit of the biomass degree of the polyester constituting the film is preferably 5%, more preferably 10%, and even more preferably 13%. A biomass degree of 5% or more can be expected to reduce the environmental impact. On the other hand, when only considering the reduction of the environmental impact, the higher the upper limit of the biomass degree, the better, with 100% being the upper limit. From the viewpoint of achieving both production costs and environmental impact reduction, a practical setting of 20% or less is preferred.

[0055] As a known method for analyzing the presence or absence of biomass raw materials, for example, the carbon isotope ( １４C).

[0056] Recycled raw materials are raw materials obtained by recovering, decomposing, and reusing polyesters that have been produced as chemical products once or multiple times. Examples of recycled raw materials for the laminate film of the present invention include uncoated sections at both ends in the width direction cut and removed during the production process of the laminate film of the present invention, recovered polyester films from other polyesters, and polyesters distributed in forms other than films, such as PET bottles. When producing a laminate film, it is preferable to use recycled raw materials in an amount of 90% by mass or less of 100% by mass of polyester raw materials. Limiting the use of recycled raw materials to 90% by mass or less reduces the amount of highly crystalline polyesters that have once been converted into chemical products, thereby reducing the deterioration of the thermal properties and transparency of the resulting laminate film and reducing coloration.

[0057] <Resin Layer (X)> The laminate film of the present invention has a resin layer (X) on the outermost surface of at least one side of the substrate resin. The resin layer (X) serves to enhance adhesion between the polyester substrate and the processed layer when the processed layer is formed. The resin layer (X) has a surface free energy of 42.5 mN / m or more and 55.0 mN / m or less, and satisfies at least one of the following conditions: "When an aqueous hard coat layer is further provided on the resin layer (X), the adhesion after boiling for 24 hours as measured by the cross-cut method is 60 / 100 or more"; or "The resin layer (X) contains one or more compounds (A) from the group consisting of alkylene glycol, acetylene glycol, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester." Preferably, both conditions are satisfied. The definitions of each parameter are as described above.

[0058] From the viewpoint that the resin layer (X) plays such a role, in the laminated film of the present invention, at least one outermost surface of the polyester substrate, preferably one outermost surface, becomes the resin layer (X). By adopting such an embodiment, when the polyester substrate and the processing layer are laminated via the resin layer (X), the laminate can be easily handled as an integrated laminate. In addition, the resin layer (X) can be designed in consideration of the adhesion of the processing layer formed by the water-based coating material, especially in a humid environment (details will be described later).

[0059] The thickness of the resin layer (X) (coating thickness after drying) is preferably 10 to 200 nm, more preferably 40 to 150 nm, and particularly preferably 60 to 120 nm. A coating thickness of 10 nm or more ensures sufficient adhesion. On the other hand, a thickness of 200 nm or less of the resin layer (X) makes it easy to maintain high appearance quality, such as transparency. The thickness of the resin layer (X) can be measured by observing a cross section of the laminate film in a direction perpendicular to the surface (thickness direction) using a transmission electron microscope (TEM).

[0060] In the laminated film of the present invention, there are further preferred design guidelines for maintaining high adhesion between the resin layer (X) and the processing layer formed from the aqueous coating material in a humid environment. The first design guideline is the water swelling rate, which is indicated by the change in mass when the resin layer (X) is dried. The water swelling rate is preferably 10 wt% or less, more preferably 7 wt% or less, and particularly preferably 5 wt% or less. By setting the water swelling rate to 10 wt% or less, water absorption from the edges becomes easier after the processing layer is formed with the aqueous coating material, preventing insufficient adhesion in the present invention. The water swelling rate can be controlled by the constituent components of the resin layer (X), the manufacturing method, and a combination thereof.

[0061] Next, as the second design guideline, the peak intensity M of the positive ion fragment exhibiting the maximum intensity in the peak intensity F detected by time-of-flight secondary ion mass spectrometry on the surface of the resin layer (X) is ＋ or the peak intensity M of the negative ion fragment showing the maximum intensity －Among these, the one with the larger absolute value is taken as the maximum peak intensity M, and the total peak intensity of the fragment derived from the compound (A) is taken as Fh, and Fh / M is preferably 0.001 or more and 0.500 or less.When Fh / M is more than 0.500, excess low molecular weight material remains at the interface, which may make it difficult to ensure the adhesion between the resin layer (X) and the processing layer formed by the water-based coating material.On the other hand, when Fh / M is less than 0.001, the formation of the resin layer (X) may be uneven, and as a result, the adhesion between the base resin and the processing layer formed by the water-based coating material may be insufficient.

[0062] The fragments detected by time-of-flight secondary ion mass spectrometry are ions generated by decomposition of compound (A) and can take various forms depending on the structure of compound (A). Here, the fragment derived from compound (A) in the present invention is the smallest structural unit that characterizes compound (A), and specifically, ４５ C ２ H ５ O ＋ or ５９ C ３ H ７ O ＋ means a fragment consisting of

[0063] The method for measuring and controlling the fragments derived from the compound (A) will be described later, but the amount of the compound (A) contained in the resin layer (X), the production method, and a combination thereof can be used to control the amount of the compound (A) contained in the resin layer (X).

[0064] Furthermore, the third design guideline is the content of fluorine element. Specifically, in the peak intensity F detected by time-of-flight secondary ion mass spectrometry on the surface of the resin layer (X), the content of negative ions (F １７－) is the peak intensity Ff, it is preferable that Ff / M is less than 0.010. The inclusion of fluorine element not only tends to reduce the initial adhesion between the resin layer (X) and the processed layer formed by the water-based coating material, but also promotes the migration of fluorine components even in a humid environment, which tends to reduce adhesion during storage. In particular, it has been confirmed that PFAS (perfluoroalkyl and polyfluoroalkyl substances) is not only undesirable from the standpoint of environmental impact, but also that when its content in the resin layer (X) exceeds 50 ppm, the aforementioned poor adhesion is likely to occur. The content of fluorine element can be controlled by selecting the constituent material of the resin layer (X) and its composition.

[0065] <Coating composition> A preferred coating composition for forming the resin layer (X) of the laminated film of the present invention will be described here. Here, the compound (A) corresponds to a surfactant for imparting coatability to the coating composition. Examples of surfactants include silicone surfactants, fluorine surfactants, and hydrocarbon surfactants, and among these, hydrocarbon surfactants are preferred.

[0066] Examples of hydrocarbon surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and other emulsifying dispersants. These may be used alone or in combination of two or more.

[0067] Examples of nonionic surfactants include (poly)alkylene oxide (AO) adduct nonionic surfactants and polyhydric alcohol nonionic surfactants. Examples of AO adducts include (poly)ethylene oxide (EO) adducts of C10-20 aliphatic alcohols, EO adducts of phenols, EO adducts of nonylphenols, EO adducts of C8-22 alkylamines, and EO adducts of poly(oxypropylene)glycols. Examples of polyhydric alcohol surfactants include fatty acid (8-24 carbon atoms) esters of polyhydric (tri- to octahydric or higher) alcohols (2-30 carbon atoms) (e.g., glycerin monostearate, glycerin monooleate, sorbitan monolaurate, sorbitan monooleate, etc.) and alkyl (4-24 carbon atoms) poly(degree of polymerization 1-10) glycosides. Commercially available nonionic surfactants include, for example, "Naroacty" (registered trademark) CL-95 and HN-100 (trade name: manufactured by Sanyo Chemical Industries, Ltd.), Lysolex BW400 (trade name: manufactured by Kokyu Alcohol Kogyo Co., Ltd.), "EMALEX" (registered trademark) ET-2020 (all manufactured by Nippon Emulsion Co., Ltd.), and "Surfynol" (registered trademark) 104E, 420, 440, 465, and "Dynol" (registered trademark) 604, 607 (all manufactured by Nissin Chemical Industry Co., Ltd.).

[0068] Examples of anionic surfactants include ether carboxylic acids or salts thereof having a hydrocarbon group having 8 to 24 carbon atoms [such as sodium lauryl ether acetate and (poly)oxyethylene (addition mole number 1 to 100) sodium lauryl ether acetate]; sulfates or ether sulfates or salts thereof having a hydrocarbon group having 8 to 24 carbon atoms [such as sodium lauryl sulfate, (poly)oxyethylene (addition mole number 1 to 100) sodium lauryl sulfate, (poly)oxyethylene (addition mole number 1 to 100) triethanolamine lauryl sulfate and (poly)oxyethylene (addition mole number 1 to 100) sodium coconut oil fatty acid monoethanolamide sulfate]; sulfonates having a hydrocarbon group having 8 to 24 carbon atoms [such as sodium dodecylbenzenesulfonate]; (C10-C20 alkyl esters), sulfosuccinates having one or two of the following substituents; phosphate esters or ether phosphate esters having a hydrocarbon group having 8 to 24 carbon atoms or salts thereof [such as sodium lauryl phosphate and (poly)oxyethylene (molar addition number 1 to 100) sodium lauryl ether phosphate]; fatty acid salts having a hydrocarbon group having 8 to 24 carbon atoms [such as sodium laurate and triethanolamine laurate]; and acylated amino acid salts having a hydrocarbon group having 8 to 24 carbon atoms [sodium coconut oil fatty acid methyl taurate, sodium coconut oil fatty acid sarcosine, triethanolamine coconut oil fatty acid sarcosine, triethanolamine N-coconut oil fatty acid acyl-L-glutamate, sodium N-coconut oil fatty acid acyl-L-glutamate, sodium lauroylmethyl-β-alanine, etc.]. Commercially available anionic surfactants include, for example, "RAPIZOL" (registered trademark) A-90, A-80, BW-30, B-90, and C-70 (all manufactured by NOF Corporation), "NIKKOL" (registered trademark) OTP-100 (all manufactured by Nikko Chemical Co., Ltd.), "KOHACOOL" (registered trademark) ON, L-40, and "PHOSPHANOL" (registered trademark) 702 (all manufactured by Toho Chemical Industry Co., Ltd.), and "VIEWRITE" (registered trademark) A-5000 and SSS (all manufactured by Sanyo Chemical Industries, Ltd.).

[0069] Examples of cationic surfactants include quaternary ammonium salt types [stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, distearyldimethylammonium chloride, lanolin fatty acid aminopropylethyldimethylammonium ethyl sulfate, etc.] and amine salt types [stearic acid diethylaminoethylamide lactate, dilaurylamine hydrochloride, oleylamine lactate, etc.].

[0070] Examples of amphoteric surfactants include betaine-type amphoteric surfactants [such as coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, lauryl hydroxysulfobetaine, and sodium lauroyl amidoethyl hydroxyethyl carboxymethyl betaine hydroxypropyl phosphate] and amino acid-type amphoteric surfactants [such as sodium β-laurylaminopropionate].

[0071] In one preferred embodiment of the laminated film of the present invention, the resin layer (X) contains at least one compound (A) selected from the group consisting of alkylene glycol, acetylene glycol, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. The presence of compound (A) in the resin layer (X) can be determined by liquid chromatography mass spectrometry (LC-MS). Details of the analysis method will be described later.

[0072] Furthermore, the surfactant contained in the coating composition for forming the resin layer (X) of the present invention has a preferred range for its HLB value. Specifically, the HLB value is preferably 10 or more and 18 or less, and particularly preferably 13 or more and 16 or less. By setting the HLB value to 10 or more, it is possible to prevent a decrease in the initial adhesion between the resin layer (X) and the processing layer formed by the water-based coating material, and by setting the HLB value to 18 or less, it is possible to prevent a decrease in adhesion during storage in a humid environment.

[0073] Methods for determining the HLB value of a surfactant include a method of calculating it from the structural formula using the radicals, and a method of experimentally calculating it by changing the compounding ratio with a material having a known HLB value. In the present invention, the HLB value is measured in accordance with the actual measurement of the HLB value by the emulsification method described in "Handbook - Cosmetics and Pharmaceutical Raw Materials - Revised Edition," published by Nikko Chemicals Co., Ltd. on February 1, 1977, pages 854-855. A specific method for determining the HLB value of the component (A) is to combine the component (A) with sorbitan monostearate (NIKKOL SS-10, HLB value 4.7) as a standard emulsifier, and emulsify liquid paraffin (HLB value 10.1) as the emulsified substance while keeping the total amount of these two emulsifiers constant and varying only the ratio. After leaving the mixture overnight, the optimal ratio of the emulsifiers that provides stability is determined from the amount of creaming, turbidity, and separation of water from the lower layer, and the HLB value x of the component (A) is calculated using the following formula (1): y = (x × amount used (mass %) + z × amount used (mass %)) / 100 ... Equation (1) In equation (1), "x" represents the HLB value of the component (A), "y" represents the HLB value of liquid paraffin, and "z" represents the HLB value of sorbitan monostearate (NIKKOL SS-10). The HLB value of liquid paraffin can be determined in a similar manner using a combination of sorbitan monostearate (NIKKOL SS-10, HLB value 4.7) and POE sorbitan monostearate (NIKKOL TS-10, HLB value 14.9). On the other hand, the fluorine-based surfactant is not particularly limited as long as it has a fluorine-containing group as the hydrophobic group, and examples thereof include perfluorooctanesulfonic acid and perfluorocarboxylic acid. Commercially available fluorine-based surfactants include, for example, "Megafac" (registered trademark) F-114, F-410, F-440, F-447, F-553, and F-556 (all manufactured by DIC Corporation), and "Surflon" (registered trademark) S-211, S-221, S-231, S-233, S-241, S-242, S-243, S-420, S-661, S-651, and S-386 (manufactured by AGC Seimi Chemical Co., Ltd.). Note that the fluorine-based surfactants are classified into those which contain negative ions (F) derived from the fluorine element as mentioned above. １７－) is defined as Ff, Ff / M is less than 0.010, and the PFAS content in the resin layer (X) is 50 ppm or less.

[0074] <Polyester Resin (B)> The resin layer (X) of the laminate film of the present invention preferably contains a polyester resin (B) containing at least a sulfo group in a side chain and having a conjugated cyclic structure in a main chain, in order to achieve both adhesion in a humid environment while maintaining the applicability of a water-based coating material.

[0075] As the dicarboxylic acid component serving as a raw material for the polyester resin, aromatic, aliphatic, and alicyclic dicarboxylic acids can be used. Examples of aromatic dicarboxylic acids that can be used include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxyethane-pp'-dicarboxylic acid, and phenylindanedicarboxylic acid. Examples of aliphatic and alicyclic dicarboxylic acids that can be used include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid, as well as ester-forming derivatives thereof.

[0076] Diol components that are raw materials for polyester resins include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol. Examples of polyester resins that can be used include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A, 4,4'-methylenediphenol, 4,4'-(2-norbornylidene)diphenol, 4,4'-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenediol, cyclopentane-1,2-diol, cyclohexane-1,2'-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, and 1,4-butanediol dimethanesulfonate. Modified polyester copolymers, such as block copolymers and graft copolymers modified with acrylic, urethane, or epoxy, can also be used as the polyester resin.

[0077] Here, the sulfo group in the side chain and the conjugated cyclic structure in the main chain will be explained. It is preferable that the polyester resin (B) has a functional group in the side chain in order to favorably control the various parameters mentioned above and maintain good adhesion between the resin layer (X) and the processed layer formed by the aqueous coating material. Examples of functional groups include hydroxyl groups, carboxylic acid groups, amide groups, glycidyl groups, isocyanate groups, and sulfo groups. From the viewpoint of maintaining adhesion of the laminated film of the present invention in a humid environment, it is particularly preferable that the side chain has a sulfo group. Sulfo groups have low reactivity with functional groups such as crosslinking agents, and a high proportion of them remain as residual functional groups after the formation of the resin layer (X), so they can be suitably used to control the physical properties of the resin layer (X).

[0078] Furthermore, in the repeating structure of the polymer main chain of polyester resin (B), preferably have the conjugated cyclic structure of benzene, naphthalene, anthracene, pyridine, pyrrole, furan, thiophene, imidazole, etc., more preferably have the conjugated cyclic structure of carbon of main skeleton such as benzene, naphthalene, etc. By having the conjugated cyclic structure, it becomes easy to keep the hydrophilic balance of resin layer (X) favorably, and as a result, it becomes easy to obtain the adhesion of the processed layer formed by water-based coating material.

[0079] <Compound (C)> The resin layer (X) of the laminated film of the present invention preferably contains at least one compound (C) selected from acrylic resins, urethane resins, epoxy resins, oxazoline compounds, and carbodiimide compounds, in order to suitably control the various parameters described above and to maintain good adhesion between the resin layer (X) and the processed layer formed by the water-based coating material. In the present invention, the compound (C) forms a different chemical structure derived from the compound (C) between the resin component and the resin component through a crosslinking reaction or the like, and even when the compound (C) alone does not exist in the resin layer (X), the resin layer (X) is broadly interpreted as containing the compound (C).

[0080] The acrylic resin is not particularly limited, but is preferably composed of alkyl methacrylate and / or alkyl acrylate.

[0081] The alkyl methacrylate and / or alkyl acrylate preferably includes methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, maleic acid, itaconic acid, acrylamide, N-methylolacrylamide, diacetone acrylamide, etc. These may be used alone or in combination of two or more.

[0082] Since the acrylic resin is a hydrophobic resin, it is also affected by the structure of the side chain, but it is thought that it reduces the adhesion between the resin layer (X) and the processed layer formed by the water-based coating material, while also contributing to suppressing a decrease in adhesion in a humid environment.

[0083] The urethane resin is preferably a resin obtained by reacting a polyhydroxy compound with a polyisocyanate compound by a known urethane resin polymerization method such as emulsion polymerization or suspension polymerization.

[0084] Examples of polyhydroxy compounds include polyethylene glycol, polypropylene glycol, polyethylene-propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, polycarbonate diol, glycerin, etc. Examples of polyisocyanate compounds that can be used include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, an adduct of trimethylenepropane, an adduct of hexamethylene diisocyanate and trimethylolethane, etc.

[0085] The above-mentioned urethane resins and their copolymers (e.g., acrylic-urethane copolymers and urethane-modified polyesters) have a highly hydrophilic crosslinked structure, and therefore, although it is also affected by the structure of the side chains, they improve the adhesion between the resin layer (X) and the processed layer formed by the aqueous coating material, but on the other hand, the adhesion may decrease in a humid environment.

[0086] As the epoxy resin, for example, a sorbitol polyglycidyl ether crosslinking agent, a polyglycerol polyglycidyl ether crosslinking agent, a diglycerol polyglycidyl ether crosslinking agent, a polyethylene glycol diglycidyl ether crosslinking agent, or the like can be used. As the epoxy resin, commercially available products may be used. Suitable examples include epoxy compounds "Denacol" (registered trademark) (EX-611, EX-614, EX-614B, EX-512, EX-521, EX-421, EX-313, EX-810, EX-830, EX-850, etc.) manufactured by Nagase Chemtec Corporation, diepoxy / polyepoxy compounds (SR-EG, SR-8EG, SR-GLG, etc.) manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., and epoxy crosslinking agents "EPICLON" (registered trademark) EM-85-75W or CR-5L manufactured by Dainippon Ink Mfg. Co., Ltd., and among these, those having water solubility are preferably used.

[0087] Since the above-mentioned epoxy resin is a hydrophilic resin, it improves the adhesion between the resin layer (X) and the processed layer formed by the water-based coating material, although it is also affected by the structure of the side chain, but on the other hand, the adhesion may decrease in a humid environment.

[0088] The oxazoline compound is preferably one having an oxazoline group as a functional group therein, and is preferably an oxazoline group-containing copolymer obtained by copolymerizing at least one monomer containing an oxazoline group and at least one other monomer.

[0089] In the oxazoline compound, at least one other monomer used for the monomer containing an oxazoline group is a monomer copolymerizable with the monomer containing an oxazoline group, and examples thereof include acrylic acid esters or methacrylic acid esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid; unsaturated nitriles such as acrylonitrile and methacrylonitrile; Examples of suitable monomers that can be used include unsaturated amides such as vinyl esters, acrylamide, methacrylamide, N-methylol acrylamide, and N-methylol methacrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride, vinylidene chloride, and vinyl fluoride; and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene. These may be used alone or in combination as long as the scope of the present invention is met.

[0090] Specific oxazoline compounds are not particularly limited, but addition-polymerizable oxazoline group-containing monomers are preferred, and examples thereof include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These may be used alone or in combination as long as they satisfy the scope of the present invention.

[0091] The carbodiimide compound is a compound having at least one carbodiimide group or a cyanamide group, which is a tautomeric form of the carbodiimide group, as a functional group in the molecule. Specific examples of such carbodiimide compounds include dicyclohexylmethanecarbodiimide, dicyclohexylcarbodiimide, tetramethylxylylenecarbodiimide, and urea-modified carbodiimide. These may be used alone or in combination as long as they satisfy the scope of the present invention.

[0092] In the present invention, the compound (C), which is a material of the coating composition preferred for forming the resin layer (X), is at least one compound selected from an acrylic resin, a urethane resin, an epoxy resin, an oxazoline compound, and a carbodiimide compound, but two or more compounds may be used in combination.

[0093] <Method for preparing coating composition> When preparing a coating composition, a solvent or a dispersion medium (hereinafter collectively referred to as solvent) may be included. That is, various components may be dissolved or dispersed in a solvent to form a coating composition, which may then be applied to a base resin. When such a method is adopted, a laminate film in which the resin layer (X) is laminated on the base resin can be obtained by drying the solvent after application and heating.

[0094] In the laminated polyester film of the present invention, it is preferable to use an aqueous solvent (W) as the solvent. Here, the aqueous solvent (W) refers to water or a mixture of water and a water-soluble organic solvent, such as an alcohol (e.g., methanol, ethanol, isopropyl alcohol, or butanol), a ketone (e.g., acetone or methyl ethyl ketone), or a glycol (e.g., ethylene glycol, diethylene glycol, or propylene glycol), in any ratio. The use of an aqueous solvent not only prevents the solvent from rapidly evaporating during the heating step, allowing for the formation of a more uniform resin layer (X), but also provides an advantage in terms of environmental impact.

[0095] In the present invention, a preferred coating composition for forming the resin layer (X) can be prepared by mixing and stirring the compound (A), polyester resin (B), and compound (C), which have been water-dispersed or water-solubilized as needed, in any order at a desired mass ratio. Next, various additives such as lubricants, inorganic particles, organic particles, surfactants, antioxidants, thermal initiators, and crosslinking catalysts can be added as needed, in any order, as long as they do not deteriorate the properties of the resin layer (X) formed by the coating composition. Examples of methods for mixing and stirring include shaking the container by hand, stirring with a magnetic stirrer or stirring blade, ultrasonic irradiation, vibration dispersion, and the like.

[0096] Examples of particles that can be used include inorganic particles such as colloidal silica, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, carbon black, and zeolite particles, and organic particles such as acrylic particles, silicone particles, polyimide particles, Teflon® particles, crosslinked polyester particles, crosslinked polystyrene particles, crosslinked polymer particles, and core-shell particles. These may be used alone or in combination. Among these, inorganic particles are preferred, and colloidal silica is more preferred, from the viewpoints of hardness for achieving the blocking suppression effect and thermal stability in a preferred manufacturing method for the laminated polyester film. When the above-mentioned colloidal silica is used as the inorganic particles, the inorganic particles are well dispersed in the resin layer (X), thereby imparting good transportability to the laminated film of the resin layer (X) while maintaining its transparency. Suitable colloidal silicas include, for example, the "Snowtex"® series manufactured by Nissan Chemical Industries, Ltd. and the "Cataloid"® series manufactured by JGC Catalysts and Chemicals Co., Ltd.

[0097] The number-average particle size of these particles is preferably in the range of 30 nm to 1000 nm. Here, the number-average particle size is the value (number average) obtained by adding up the particle sizes of primary particles, defined in JIS H7008 (2002) as particles generated by the growth of a single crystal nucleus, and dividing the sum by the number of particles. The number-average particle size of the particles is more preferably in the range of 40 nm to 450 nm, and even more preferably in the range of 80 nm to 300 nm. The particles may be monodisperse particles or agglomerated particles formed by agglomeration of multiple particles. In some cases, multiple types of particles with different number-average particle sizes may be used in combination. The number-average particle size of the particles can be measured by particle size distribution analysis using dynamic light scattering in the case of a coating composition, or by shape analysis using SEM-EDX in the case of a laminated polyester film.

[0098] <Method for manufacturing laminated film> The resin layer (X) of the present invention is preferably formed by applying the above-mentioned preferred coating composition to at least one surface of a base resin and heating it to form a resin layer (X). In this formation method, the coating composition may contain one or more compounds (A) selected from the group consisting of alkylene glycol, acetylene glycol, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester, a polyester resin (B), and at least one compound (C) selected from an acrylic resin, a urethane resin, an epoxy resin, an oxazoline compound, and a carbodiimide compound, as well as various additives such as a crosslinking catalyst, a lubricant, inorganic particles, organic particles, a surfactant, an antioxidant, and a thermal initiator.

[0099] The coating composition can be applied to a base resin by either an in-line coating method or an off-coating method, but the in-line coating method for a polyester base material is preferred. Hereinafter, when the target base resin is omitted, the in-line coating method for a polyester base material is referred to. The in-line coating method refers to a method in which a coating composition is applied within the manufacturing process of a polyester base material (polyester film). Specifically, it refers to a method in which coating is performed at any stage from melt extrusion of a polyester resin to biaxially stretching, heat treatment, and winding up. Typically, the coating is applied to either a substantially amorphous unstretched (unoriented) polyester film obtained by melt extrusion and quenching (hereinafter sometimes referred to as "A film"), a uniaxially stretched (uniaxially oriented) polyester film (hereinafter sometimes referred to as "B film") that has been subsequently stretched in the longitudinal direction, or a biaxially stretched (biaxially oriented) polyester film (hereinafter sometimes referred to as "C film") that has been further stretched in the width direction and before heat treatment.

[0100] In the present invention, a preferred method is to apply a coating composition to either the A film or the B film of a polyester film before the crystal orientation is complete, evaporate the solvent, and then stretch the polyester film uniaxially or biaxially and heat it to complete the crystal orientation of the polyester film, thereby providing the resin layer (X). This method allows the production of a polyester film (corresponding to the polyester substrate of the laminated film of the present invention), the application of the coating composition, the drying of the solvent, and the heating (i.e., the formation of the resin layer (X)) to be carried out in a continuous process. In particular, when coating the B film, the heat treatment process (thermal setting) after stretching the polyester film in the width direction, the drying of the coating composition, and the heating (i.e., the formation of the resin layer (X) by thermosetting) can be carried out in the same process. This not only has advantages in terms of production cost, but also allows the completion of the crystal orientation of the polyester substrate after drying, thereby enabling the coating layer to be subjected to high-temperature heat treatment while reducing deformation and thermal shrinkage of the substrate. As a result, crosslinking of the resin layer (X) formed by coating is promoted, and even after forming a processing layer using a water-based functional material, poor adhesion due to moisture penetration is less likely to occur. Another advantage is that the thickness of the resin layer (X) can be easily made thinner and more uniform by stretching it after coating.

[0101] The heat treatment (thermosetting) of the coating layer has preferred temperature conditions from the viewpoint of sufficiently promoting the crosslinking reaction of the resin layer (X) and suppressing poor adhesion due to moisture penetration. Specifically, the resin layer (X) is preferably formed by thermosetting at a heat treatment temperature of 170°C or higher, more preferably 180°C or higher, even more preferably 200°C or higher, and particularly preferably 230°C or higher. The upper limit of the heat treatment temperature is preferably 260°C in view of the heat resistance temperature of the polyester film. By setting the heat treatment temperature to 260°C or lower, deformation of the polyester film is suppressed, making it easier to obtain a more uniform laminated polyester film.

[0102] Among these, a method in which a coating composition is applied to a film (film B) uniaxially stretched in the longitudinal direction, the solvent is dried, and then the film is stretched in the width direction and heated is excellent. This is because, compared with a method in which a coating composition is applied to an unstretched film and then biaxially stretched, this method requires one less stretching step for the layer formed from the coating composition, making it less likely for defects or cracks to occur in the resin layer (X) due to stretching, and making it possible to form a resin layer (X) with excellent transparency and smoothness.

[0103] On the other hand, the offline coating method is a method in which a coating composition is applied in a separate process from the film-forming process. In the case of a polyester substrate, a coating layer can be formed on the film after the A film is uniaxially or biaxially stretched and heat-treated to complete the crystalline orientation of the polyester film, or on the A film itself. In the present invention, the in-line coating method is preferred due to the various advantages described above. However, even when the resin layer (X) is formed by the offline coating method, the processing temperature is preferably 170°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher. By setting the processing temperature to 170°C or higher, the crosslinking reaction can be promoted and the thin-film resin layer (X) can be sufficiently cured.

[0104] In particular, from the viewpoint of sufficiently promoting the crosslinking reaction of the resin layer (X) and suppressing poor adhesion due to moisture penetration in a humid environment, even when the same formulation is used, the adhesion of the processed layer formed by the resin layer (X) and the water-based coating material may be insufficient unless the processing temperature is 170 ° C. or higher. The upper limit of the processing temperature is preferably 260 ° C. in view of the heat resistance temperature of the polyester film. By keeping the processing temperature at 260 ° C. or lower, deformation of the polyester film is suppressed, making it easier to obtain a uniform laminated polyester film.

[0105] Here, the coating method for the coating composition on the polyester film can be any method selected from known coating methods, such as bar coating, reverse coating, gravure coating, die coating, blade coating, etc., for both in-line coating and offline coating.

[0106] Therefore, a preferred method for forming the resin layer (X) in the present invention is to apply a coating composition using an aqueous solvent to a polyester substrate using an in-line coating method, followed by drying and heat treatment. A more preferred method is to in-line coat the coating composition onto the uniaxially stretched B film. In the method for producing the laminated film of the present invention, drying is preferably carried out at a temperature range of 80 to 130°C to complete removal of the solvent from the coating composition. Furthermore, heat treatment is preferably carried out at a temperature range of 170 to 260°C to complete the crystal orientation of the polyester film and the thermal curing of the coating composition, thereby completing the formation of the resin layer (X).

[0107] Next, a preferred method for producing the laminated film of the present invention will be described in more detail using an example in which a polyethylene terephthalate (hereinafter, PET) film is used as the polyester substrate, but the laminated film of the present invention and its production method are not limited to this.

[0108] First, PET pellets are thoroughly vacuum-dried, then fed into an extruder, melt-extruded into a sheet at 260°C to 280°C, and cooled to solidify, producing an unstretched (unoriented) PET film (film A). (In this case, the melt-extruded sheet is preferably cooled and solidified using a cast drum at a temperature of 10°C to 40°C.) This unstretched PET film is stretched 2.5 to 5.0 times in the longitudinal direction using a roll heated to 80 to 120°C, to produce a uniaxially oriented PET film (film B). Furthermore, the aforementioned coating composition, adjusted to a predetermined concentration, is applied to one side of film B.

[0109] In this case, the surface of the uniaxially oriented PET film to be coated may be subjected to a surface treatment such as corona discharge treatment before applying the coating composition. Surface treatment such as corona discharge treatment improves the wettability of the coating composition to the uniaxially oriented PET film, preventing repellency of the coating composition and allowing the formation of a resin layer (X) with a more uniform coating thickness. After applying the coating composition, the edges of the uniaxially oriented PET film are held with clips, and the solvent of the coating composition is dried in a heat treatment zone (preheating zone) at 80 to 130°C. In particular, when sending the uniaxially oriented PET film coated with the coating composition to the heat treatment zone, it is preferable to hold the uncoated portions of both widthwise ends of the uniaxially oriented PET film with clips and guide it to a tenter. After drying, the film is stretched widthwise by 1.1 to 5.0 times, and subsequently introduced into a heat treatment zone (thermal setting zone) at 170 to 260°C, where it is heat-treated for 1 to 30 seconds to complete the crystal orientation.

[0110] During this heat treatment process (thermal setting process), a relaxation treatment of 3 to 15% may be performed in the width direction or longitudinal direction as needed. The laminated polyester film is then cooled to room temperature, and the laminated film is cut parallel to the longitudinal direction with a known razor blade or the like to remove the uncoated portions at both ends of the width direction that were gripped by the clips, and then wound into a roll. The resulting laminated film exhibits excellent adhesion to the processing layer formed with the water-based coating material, even in a humid environment. The uncoated portions of the film at both ends of the width direction cut and removed with a slitter can be used as the recycled raw material described above.

[0111] In the laminate film of the present invention, an intermediate layer may be provided between the resin layer (X) and the base resin, but when an intermediate layer is provided, the film may be scratched when the film having the intermediate layer laminated thereon is taken up or in the subsequent process up to the provision of the resin layer (X) of the present invention. Therefore, in the present invention, it is preferable that the resin layer (X) and the base resin are directly laminated.

[0112] The base resin constituting the laminate film of the present invention is not limited in its layer configuration, and examples thereof include a single-layer configuration consisting of only Layer A, a laminate configuration of Layer A / Layer B, i.e., a two-type two-layer laminate configuration, a laminate configuration of Layer A / Layer B / Layer A, i.e., a two-type three-layer laminate configuration, and a laminate configuration of Layer A / Layer B / Layer C, i.e., a three-type three-layer laminate configuration.

[0113] The lamination method of the base resin constituting the laminate film of the present invention is not limited, and examples thereof include a lamination method using a coextrusion method, a lamination method using lamination, and a combination thereof. However, from the viewpoint of transparency and manufacturing stability, it is preferable to adopt a coextrusion method. When forming a laminate, different resin structures may be used to impart different functions to each layer. For example, in the case of a laminate structure of A layer / B layer / A layer, i.e., a two-type three-layer laminate structure, from the viewpoint of transparency, a method can be used in which particles for imparting easy slippage are unevenly distributed in A layer.

[0114] <Laminate, Processing Layer (Y)> The laminate of the present invention will be described below. The laminate of the present invention has a processing layer (Y) on the surface of the resin layer (X) of the laminate film of the present invention. That is, the laminate film of the present invention is preferably used to manufacture a laminate in which a processing layer (Y) is further formed on the resin layer (X). In addition, a wet coating method is preferably used to form the processing layer (Y), and the coating material for forming the processing layer (Y) is preferably an "aqueous coating material" in which water is the main solvent or dispersion medium. Here, "water as the main solvent or dispersion medium" means that the proportion of water in 100% by mass of the materials constituting the solvent or dispersion medium exceeds 50% by mass. The processing layer (Y) can be formed by any method selected from known coating methods, such as bar coating, reverse coating, gravure coating, die coating, blade coating, etc.

[0115] Furthermore, the processing layer (Y) is preferably a function-imparting layer that imparts physical properties different from those of the base resin. Examples of the functions imparted include scratch prevention, electrical conductivity and antistatic properties, adhesive properties, prevention of various adhesions such as stains, transmission and absorption of various light rays from infrared to visible to ultraviolet, and easy peeling usable for protection of adherends and transfer processing. In particular, in the laminate of the present invention, it is particularly preferred that the processing layer (Y) contains at least one of a hard coating agent, an adhesive, and a printing ink, for example, for use in a laminate film having adhesion and transparency.

[0116] Next, the present invention will be described in more detail based on examples, but the present invention is not necessarily limited thereto. The methods for measuring each property and evaluating each effect in the present invention are as follows.

[0117] [Methods for measuring properties and evaluating effects] (1) Surface free energy of resin layer (X) First, the laminated film was left for 24 hours in an atmosphere at room temperature of 23°C and a relative humidity of 65%. Thereafter, in the same atmosphere, the contact angles of four liquids, namely, pure water, ethylene glycol, formamide, and diiodomethane, were measured at five points on the resin layer (X) using a contact angle meter DM-501 (manufactured by Kyowa Interface Science Co., Ltd.), and the average of the measured values ​​was taken as the contact angle of each liquid. Next, using the contact angles of the four liquids obtained, the surface free energy (γ) of the solid was calculated by the geometric mean method based on the "extended Fowkes equation" proposed by Hata et al., and the dispersion force component (γ Ｓ ｄ ), polar force component (γ Ｓ ｐ ), and hydrogen bonding strength component (γ Ｓ ｈ The surface energy, which is the dispersion force, polar force, hydrogen bonding force, and the sum of the dispersion force and polar force, was calculated. The specific calculation method is shown below. The meaning of each symbol is explained below. γ Ｓ Ｌ γ: Surface energy of the resin layer and the known solution listed in Table 1 Ｓ　 : Surface energy of resin layer γ Ｌ　 : Surface energy γ of the known solution listed in Table 1 Ｓｄ : Dispersion force component of the surface energy of the resin layer γ Ｓ ｐ : Polar component of the surface energy of the resin layer γ Ｓ ｈ : Hydrogen bonding force component of the surface energy of the resin layer γ L ｄ γ: dispersion force component of the surface energy of the known solution listed in Table 1 L ｐ γ: Polar force component of the surface energy of the known solutions listed in Table 1 L ｈ γ: Hydrogen bonding force component of the surface energy of the known solutions listed in Table 1 Ｓ Ｌ When γ is the tension at the interface between the solid and the liquid, the following equation (2) holds: Ｓ Ｌ = γ Ｓ +γ Ｌ -2(γ Ｓ ｄ ・γ Ｌ ｄ ) １／２ -2(γ Ｓ ｐ ・γ Ｌ ｐ ) １／２ -2(γ Ｓ ｈ ・γ Ｌ ｈ ) １／２ ...Equation (2).

[0118] Furthermore, the state when a droplet is in contact with a smooth solid surface at a contact angle (θ) is expressed by the following equation (3) (Young's equation): γ Ｓ = γ Ｓ Ｌ +γ Ｌ cosθ...Equation (3).

[0119] Combining these formulas (2) and (3), the following formula is obtained: (γ Ｓ ｄ ・γ Ｌ ｄ ) １／２ +(γ Ｓ ｐ ・γ Ｌ ｐ ) １／２ +(γＳ ｈ ・γ Ｌ ｈ ) １／２ = γ Ｌ (1+cosθ) / 2...Equation (4).

[0120]

[0121] In practice, the contact angle (θ) and the surface tension components (γ) of the known liquids listed in Table 1 were measured for four types of liquids: water, ethylene glycol, formamide, and diiodomethane. L ｄ , γ L ｐ , γ L ｈ ) into Equation (3) and solve the four simultaneous equations. As a result, the surface energy of the solid (γ), the dispersion force component (γ Ｓ ｄ ), polar force component (γ Ｓ ｐ ), and hydrogen bonding strength component (γ Ｓ ｈ ) and the total value, the surface free energy was calculated. (2) Thickness of Resin Layer (X) The thickness of the resin layer (X) on the polyester substrate was measured by observing the cross section using a transmission electron microscope (TEM). The thickness of the resin layer was read from an image taken at a magnification of 200,000 times using a TEM. The thickness of the resin layer was measured at a total of 20 points, and the average value was taken as the thickness of the resin layer (X).

[0122] (3) Water Swelling Rate of Resin Layer (X) The water content of the resin layer (X) was quantified by thermal evolved gas analysis (TPD-MS). The specific procedure is as follows. First, the resin layer (X) was scraped off from the laminated film with a diamond file (#200) to obtain a total of 100 mg of powder. At this time, the composition of the surface of the resin layer (X) side of the laminated film before and after scraping was observed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) described below, and fragments derived from the base resin, in the case of polyethylene terephthalate, were identified. １２１ C ７ H ５ O ２ － , ３５７ C１８ H １３ O ８ － , ４７５ C ２６ H １９ O ９ － (both negative ions) were confirmed to be absent.

[0123] The obtained powder was then left for 24 hours in an atmosphere of room temperature 23°C and relative humidity 65%. A heating device with a temperature controller was directly connected to a mass spectrometer, and the powder was placed on the heating stage. Helium gas was then passed through the powder at 50 ml / min for 15 minutes as a preparatory step. The temperature was then raised from room temperature to 120°C at a rate of 10°C / min in a helium atmosphere. The water content of the resin layer (X) was determined by analyzing and integrating the concentration of water generated from the resin layer (X) during heating. The water swelling rate (%) was calculated by dividing the water content by the sample mass after the temperature increase treatment (i.e., the mass of the resin layer (X) from which water had been removed). The measurement equipment and conditions were as follows: Mass spectrometer: Shimadzu GC / MS QP5050A MS sensitivity: Gain 1.40 kV Mass number: m / z = 18 (H ２ O) Atmosphere: Helium flow rate (50 ml / min) Sample mass: 100 mg.

[0124] (4) Method for Analyzing the Composition of the Resin Layer (X) Surface The composition of the resin layer surface of the laminated film was analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The measurement conditions were as follows. In the obtained chart, the peak intensity M of the fragment showing the maximum intensity and the peak of each fragment used for analysis were determined. <Measurement Conditions> Measurement device: TOF.SIMS 5 (manufactured by ION-TOF) Analysis software: SurfaceLab Primary ion: Bi ３ ＋＋ Primary ion acceleration voltage: 25 kV Secondary ion polarity: positive ions and negative ions Mass range: m / z 0 to 1,000 Measurement range: 400 μm x 400 μm Number of scans: 25 scans Pulse width: 10.2 ns Bunching: Yes Charge neutralization: Yes Post-acceleration: 9.5 kV Measurement vacuum: 1 x 10 －７ Pa or less.

[0125] (4-1) Negative ions derived from fluorine element (F １７- ) peak intensity Ff and Ff / M, which are peaks derived from fluorine element, negative ions (F １７- The peak intensity Ff of the fragment with the maximum intensity was divided by the peak intensity M of the fragment with the maximum intensity for negative ions. The measurement was repeated three times, and the average value was taken as Ff / M.

[0126] (4-2) Total peak intensity Fh and Fh / M of fragments derived from compound (A) Similarly, from the obtained chart (horizontal axis: mass number / vertical axis: signal intensity), the fragments of compound (A) contained in the resin layer and the resin substrate, i.e. ４５ C ２ H ５ O ＋ , ５９ C ３ H ７ O ＋ The peak intensity of the fragment of the resin substrate and the peak intensity of the fragment of the resin substrate were then read. Next, in order to uniformly calculate the positive and negative ions and to eliminate the measurement difference between samples, the peak intensity M of the fragment of the positive ion showing the maximum intensity was calculated. ＋ or the peak intensity M of the negative ion fragment showing the maximum intensity － The largest absolute value was defined as the maximum peak intensity M, and Fh was normalized to a dimensionless quantity by dividing it by M. The measurement was repeated three times, and the average value was taken as Fh / M, which is the sum of the peak intensities of the fragments derived from compound (A).

[0127] (5) Determination of whether or not compound (A) is contained in resin layer (X): The polyester resin composition is immersed in dichloromethane at room temperature for 24 hours, reprecipitated with methanol, centrifuged, and the supernatant is collected. The supernatant is heated to 40°C while gently spraying nitrogen gas onto it, concentrated, and then diluted with methanol to obtain an LC / MS sample. Compound (A) in the LC / MS sample is qualitatively analyzed using an LC-MS device. The measurement conditions are as follows: <LC conditions> Apparatus: 1100 Series manufactured by Agilent Technology Column: Inertsil C8 (250 × 2.1 mm, 3 μm) Flow rate: 0.2 mL / min Mobile phase: 20 mM aqueous ammonium acetate solution / methanol = 17 / 83 Column thermostat: 40°C Injection volume: 10 μm Detection mode: ESI negative Drying gas: N2 (350°C, 10 L / min) Nebulizer pressure: 50 psig Fragmentor voltage: 140 V Capillary voltage: 5000 V (6) PFAS content of resin layer (X) 250 parts by mass of methanol was added to 100 parts by mass of the powder of resin layer (X) obtained in the same manner as in (3), and the mixture was subjected to ultrasonic treatment at 60°C for 120 minutes to extract PFAS. The PFAS content of the resulting liquid phase was measured using a liquid chromatograph mass spectrometer (Agilent, 1260HPLC / 6460MS) in accordance with British Standard (BSI) CEN / TS 15968 (2010), with a detection limit of 1 ppb by mass.

[0128] (7) Measurement of total light transmittance and haze of laminated film: Five square laminated film samples, each 5 cm on a side, were prepared. The samples were then left at room temperature (23°C, 50% relative humidity) for 40 hours. The total light transmittance and haze of each sample were measured using a turbidity meter "NDH5000" manufactured by Nippon Denshoku Industries Co., Ltd., in accordance with JIS "Determination of haze for transparent materials" (K7136 2000 edition). The total light transmittance and haze values ​​of each of the five samples were averaged to obtain the total light transmittance and haze values ​​of the laminated film.

[0129] (8) Application of a hard coat processing layer using a water-based coating material The non-volatile components as the water-based UV-curable hard coat component were adjusted as follows. In a beaker, 100.0 parts by weight of a mixture of dipentaerythritol penta- and hexaacrylate (Aronix M-402, manufactured by Toagosei Co., Ltd.) as a film-forming component, 65.0 parts by weight of a 10% aqueous solution of sodium dodecylbenzenesulfonate (Neopelex G-25, manufactured by Kao Corporation) as an emulsifier, 35.0 parts by weight of a 10% aqueous solution of polyoxyethylene lauryl ether (Emulgen 147, manufactured by Kao Corporation), and 110.0 parts by weight of ion-exchanged water were added and stirred and mixed. Then, while cooling in an ice bath, ultrasonic irradiation for 120 seconds was performed three times using an ultrasonic disperser (UH-600S, manufactured by SMT Co., Ltd.) to obtain a UV-curable emulsion. Next, the above emulsion was subjected to a micronization treatment using a high-pressure homogenizer (Microfluidizer M110Y, manufactured by Mizuho Kogyo Co., Ltd.) under a pressure of 70 MPa. The average particle size of the oil droplets in the UV-curable emulsion was 400 nm. 3 parts by mass of a photoinitiator "OMNIRAD" (registered trademark) 819DW manufactured by IGM Resin B.V. was blended with 97 parts by mass of the solid content of the obtained UV-curable emulsion to form an aqueous UV-curable hard coat component. Furthermore, the concentration of the above-mentioned water-based UV-curable hard coat components was adjusted by blending pure water, and a nonionic surfactant ("Surfynol" (registered trademark) 465 manufactured by Nissin Chemical Industry Co., Ltd.) was mixed as a surfactant at 0.1 wt % of the total coating material to obtain a water-based UV-curable hard coat coating material. The obtained water-based UV-curable hard coat coating material was applied to the surface of the resin layer (X) of the laminated polyester film by wire bar coating to a thickness of approximately 1 μm, and after drying at 120° C. for 1 minute, it was subjected to irradiation using an ultraviolet lamp with an irradiation intensity of 120 W / cm, an irradiation distance (distance between the lamp and the coated surface of the water-based coating material) of 12 cm, a conveyor speed of 2 m / min, and an integrated intensity of approximately 300 mJ / cm. ２ The thickness of the hard coat layer was adjusted to about 1 μm by blending pure water so that the nonvolatile content of the coating agent was 30% by mass and selecting a wire bar to be used in the wire bar coating method.

[0130] (9) Evaluation of adhesion of hard coat <Cross-cut method> The hard coat laminate film sample obtained in (8) was cut into a size of 10 cm x 10 cm, each piece fixed to a clip and hung up, and then placed in boiling pure water (100°C) prepared in a beaker for 24 hours with the entire laminated polyester film immersed. Thereafter, the sample for evaluation of boiling adhesion resistance was taken out and dried at normal conditions (23°C, relative humidity 65%) for 1 hour to obtain a hard coat laminate sample for boiling adhesion resistance test.

[0131] Next, in accordance with JIS K5600-5-6 (established in 1999), 25 slits were made in a 5 x 5 pattern with a cut interval of 1 mm. Next, 18 mm of "Cellotape" (registered trademark) (Nichiban Co., Ltd. product number: CT-18S) was firmly rubbed with a finger on the slit area and pressed down so that the slits were visible. The "Cellotape" (registered trademark) was then instantly peeled off at an angle of approximately 60° to the hard coat layer. Thereafter, the number of squares where the hard coat layer remained was counted. The evaluation was performed four times as one set (100 squares in total), and the adhesion of the hard coat was evaluated using the average value (rounded up to the nearest whole number) of the five sets.

[0132] (10) Storage stability of processed layer formed with aqueous coating material in a humid environment The hard coat laminate film sample obtained in (8) was cut into a size of 10 cm x 10 cm and left in a thermo-hygrostat at a temperature of 85 ° C and a relative humidity of 85% for 500 hours to obtain a sample for a moist heat resistance adhesion test. The obtained moist heat resistance adhesion test sample was subjected to an adhesion test in the same manner as in (9), and the number of remaining lattices was used as an index of adhesion in a humid environment.

[0133] [Compound (A)] First, the following compounds and resins were prepared to prepare a coating composition. Compound a1: Ethylene oxide-added acetylene glycol ("Surfynol" (registered trademark) 485, manufactured by Nissin Chemical Industry Co., Ltd., HLB value: 17) Compound a2: Ethylene oxide-added acetylene glycol ("Surfynol" (registered trademark) 440, manufactured by Nissin Chemical Industry Co., Ltd., HLB value: 8) Compound a3: Ethylene oxide-added acetylene glycol ("Surfynol" (registered trademark) 465, manufactured by Nissin Chemical Industry Co., Ltd., HLB value: 13) [Resin (B)] (Reference Example 1) Resin b1: An aqueous dispersion of a polyester resin having the following copolymerization composition was obtained. The following copolymerization components and 0.1 parts of potassium titanium oxalate as a catalyst were added to a reactor, and the mixture was heated to 200°C under normal pressure in a nitrogen atmosphere while stirring and mixing. Next, the reaction temperature was gradually raised to 250°C over 4 hours to complete the transesterification reaction. 15 parts by mass of the polyester resin thus obtained and 85 parts by mass of water were added to a dissolution tank and dispersed under stirring at a temperature of 80 to 95°C for 2 hours to obtain a 15% by mass aqueous dispersion of the polyester resin. This was designated Resin b1. <Copolymerization Components> (Dicarboxylic Acid Component) 2,6-Dimethylnaphthalenedicarboxylate: 88 mol% 5-Dimethylsodium sulfoisophthalate: 12 mol% (Diol Component) Compound in which 2 moles of ethylene oxide are added to 1 mole of bisphenol S: 86 mol% 1,3-Propanediol: 14 mol% Resin b2: "PLASCOAT" (registered trademark) Z760 (containing —COOH groups, solids concentration 25% by mass, acid value 50 mgKOH / g), manufactured by GOO Chemical Industry Co., Ltd., was designated Resin b2.

[0134] (Reference Example 2) Resin b3: In the same manner as in Reference Example 1, an aqueous dispersion of a polyester resin composed of the following copolymer components was obtained, and designated Resin b3.

[0135] <Copolymerization Components> (Dicarboxylic Acid Component) Maleic anhydride: 100 mol % (Diol Component) Compound in which 2 moles of ethylene oxide are added to 1 mole of bisphenol S: 86 mol % 1,3-propanediol: 14 mol % [Compound (C)] (Reference Example 3) Compound c1: Under a nitrogen gas atmosphere and at room temperature (25°C), 100 parts by mass of water, 1 part by mass of sodium lauryl sulfate, and 0.5 parts by mass of ammonium persulfate were charged into a vessel 1, and the temperature was raised to 70°C to dissolve the sodium lauryl sulfate, thereby obtaining a solution 1 at 70°C. At room temperature (25°C), 30 parts by mass of water and 2 parts by mass of sodium lauryl sulfate were added to container 2 to dissolve the sodium lauryl sulfate. Then, 13.3 parts by mass of polyethylene oxide monomethacrylate (having 10 repeating units of ethylene oxide) was added as an acrylic monomer component having a polyalkylene oxide, and 29.7 parts by mass of ethyl acrylate, 50.0 parts by mass of methyl methacrylate, and 5.0 parts by mass of N-methylolacrylamide were added as other monomer components, followed by stirring to obtain solution 2. Under a nitrogen gas atmosphere, solution 1 was transferred to a reactor, and while maintaining the temperature of the solution in the reactor at 70°C, solution 2 was continuously added dropwise to solution 1 over 3 hours. After completion of the dropwise addition, the mixture was further stirred at 85°C for 2 hours, then cooled to 25°C to terminate the reaction, yielding an acrylic resin emulsion. This was designated compound c1.

[0136] Compound c2: "Hydran" (registered trademark) AP-40 (solid content concentration: 40% by mass) manufactured by DIC Corporation was used as compound c2.

[0137] Compound c3: Carbodiimide aqueous crosslinking agent (Nisshinbo Chemical Inc.'s "Carbodilite" (registered trademark) V-04) Compound c4: Oxazoline-containing polymer aqueous dispersion (Nippon Shokubai Co., Ltd.'s "Epocross" (registered trademark) WS-500) [Other components] The following materials were also used as slippery particles. Inorganic particles d: Silica particles having a number average particle size of 100 nm (Nissan Chemical Industries, Ltd.'s "Snowtex" (registered trademark) MP-1040).

[0138] The number average particle size can be determined for a film by analyzing particle images observed by a cross-section using a transmission electron microscope (TEM), and for a coating composition by number-based analysis using a dynamic light scattering (DLS) method.

[0139] Example 1 Coating Composition First, 0.5 parts by mass of inorganic particles d were added to 100 parts by mass of resin b1. After adjusting the concentration with water as a solvent, 0.1 parts by mass of compound a1 was added to a total of 100 parts by mass of the entire coating composition, including water, to adjust the coatability. Here, the method for adjusting the concentration using water will be described in detail. Specifically, the concentration was determined according to the target thickness of the resin layer (X) using the following method. The thickness of the resin layer (X) is proportional to the concentration of the coating composition and the coating thickness, and inversely proportional to the widthwise stretching ratio and the specific gravity of the resin layer (X). Of these, the coating thickness is uniquely determined by the number used for bar coating, and the stretching ratio is uniquely determined by the film-forming conditions. Therefore, multiple concentrations of the coating composition were prepared in advance, and a calibration curve was created by measuring the thickness of the resin layer (X) using the method described above, and the concentration of the coating composition matching the target thickness of the resin layer (X) was determined. The concentration of the resulting coating composition was generally 2.5% to 4.5% by mass. Thus, a coating composition was obtained.

[0140] <Laminated Polyester Film> PET pellets (intrinsic viscosity 0.64 dl / g) containing two types of particles (4% by mass of silica particles with a primary particle size of 0.3 μm and 2% by mass of calcium carbonate particles with a primary particle size of 0.8 μm) were thoroughly vacuum-dried, fed into an extruder, melted at 280°C, extruded into a sheet from a T-shaped die, and wrapped around a mirror-finished casting drum at a surface temperature of 25°C by an electrostatic casting method, where it was cooled and solidified. The composition and particle size of the particles contained in the PET pellets were measured by a combination of shape analysis by TEM and elemental analysis by energy dispersive X-ray spectroscopy (EDX) on thin film sections prepared using a cryomicrotome. On the other hand, the intrinsic viscosity was measured by an extrapolation method according to JIS K 7367:2002, in which PET pellets were dissolved in a solvent capable of dissolving the pellets (e.g., hexafluoroisopropanol), viscosity measurements were carried out at a plurality of concentrations, and the viscosity at 100% (i.e., the intrinsic viscosity) was calculated from an approximation curve.

[0141] The unstretched film (Film A) thus obtained was heated to 90°C and stretched 3.1 times in the longitudinal direction to produce a uniaxially stretched film (Film B). The uniaxially stretched film was then subjected to a corona discharge treatment in air, after which the above-mentioned coating composition was applied using a bar coater (wire bar #4). The uniaxially stretched film coated with the coating composition was then clamped at both widthwise ends with clips and introduced into a preheating zone. The ambient temperature in the preheating zone was set to 90-100°C, and the solvent in the coating composition was dried. Subsequently, the film was continuously stretched 3.6 times in the widthwise direction in a 100°C stretching zone and heat-treated for 20 seconds in a 240°C heat treatment zone to form a resin layer (X). Further, a 5% relaxation treatment in the widthwise direction at the same temperature was performed to obtain a laminated polyester film in which the polyester film had completed its crystalline orientation. In the resulting laminated polyester film, the PET film (polyester substrate) had a thickness of 50 μm, and the resin layer (X) had a thickness (film thickness) of 80 nm. The evaluation results are shown in Tables 3 and 4.

[0142] (Examples 2 to 13, 16 to 18, Comparative Examples 3 and 4) Laminated polyester films were obtained in the same manner as in Example 1, except that the composition of the compounds and resins in the coating composition and the thickness of the resin layer (X) were as shown in Table 2. In the obtained laminated polyester films, the thickness of the PET film (polyester substrate) was 50 μm, and other evaluation results are shown in Tables 3 and 4.

[0143] Comparative Example 1 A laminated film was obtained in the same manner as in Example 1, except that 0.1 parts by mass of a silicone surfactant (KF-6043, manufactured by Shin-Etsu Silicones Co., Ltd., HLB value: 14.5) was used instead of compound (A). In the obtained laminated film, the thickness of the PET film (polyester substrate) was 50 μm, and other evaluation results are shown in Tables 3 and 4.

[0144] Comparative Example 2 A laminated polyester film was obtained in the same manner as in Example 1, except that 0.1 parts by mass of a fluorine-based surfactant ("PLASCOAT" (registered trademark) RY-2, manufactured by GOO Chemical Industry Co., Ltd.) was used instead of compound (A). In the obtained laminated film, the thickness of the PET film (polyester base material) was 50 μm, and other evaluation results are shown in Tables 3 and 4.

[0145] Examples 14 and 15 Laminated polyester films were obtained in the same manner as in Example 12, except that recycled materials and biomass materials were used as raw materials for the polyester substrate in the proportions shown in Table 2. The evaluation results are shown in Tables 3 and 4.

[0146] The recycled raw material was prepared by shredding the uncoated portions at both ends in the width direction that had been gripped by the clips in the tenter, which had been removed in the film-forming process in Examples 2 to 13, 16, and 17 and Comparative Examples 1 to 4, and kneading them with virgin raw material. On the other hand, the biomass raw material was prepared in the same manner as the starting raw material, except that PET pellets (biomass content 15%) in which part of the ethylene glycol had been replaced with plant-derived monoethylene glycol were used.

[0147]

[0148]

[0149]

[0150] The present invention relates to an easily adhesive film that exhibits excellent adhesion to a processing layer formed from a water-based coating material, even in a humid environment, and can be used for magnetic recording materials, packaging materials, optical films such as anti-reflection films, diffusion sheets, and prism sheets used in flat displays, etc., transparent touch panels, etc. In particular, the film can be suitably used for products that include post-processing steps using water-based coating materials such as water-based hard coating agents, water-based pressure-sensitive adhesives, and water-based printing inks, more specifically, display components or packaging materials that require water resistance.

[0151] Furthermore, the laminate of the present invention, which has a processing layer (Y) on the surface of the resin layer (X), can be suitably used as a display member or a packaging material.

Claims

1. A laminated film having a base resin and a resin layer (X) on at least one side of the base resin, wherein the resin layer (X) satisfies the following characteristics: (1) The surface free energy of the resin layer (X) is 42.5 mN / m or more and 55.0 mN / m or less. (2) When an aqueous hard coat layer is further provided on the resin layer (X), the adhesion after boiling for 24 hours is 60 / 100 or more as measured by the cross-cut method.

2. A laminated film having a base resin and a resin layer (X) on at least one side of the base resin, wherein the resin layer (X) satisfies the following characteristics: (1) The surface free energy of the resin layer (X) is 42.5 mN / m or more and 55.0 mN / m or less. (2) The resin layer (X) contains one or more compounds (A) selected from the group consisting of alkylene glycol, acetylene glycol, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

3. The laminated film according to claim 2, further satisfying the following characteristics: (1) When a water-based hard coat layer is further provided on the resin layer (X), the adhesiveness after boiling for 24 hours measured by the cross-cut method is 60 / 100 or more.

4. The laminate film according to any one of claims 1 to 3, wherein the resin layer (X) has a water swelling rate of 10 wt % or less. Water swelling rate (%): a value calculated by taking the mass of the resin layer (X) after leaving it in an atmosphere of room temperature (23°C) and relative humidity 65% ​​for 24 hours, raising the temperature from room temperature to 120°C at a rate of 10°C / min, analyzing and integrating the concentration of water generated from the resin layer (X) during heating, and dividing the aforementioned water amount by the mass of the sample after the heating treatment (i.e., the mass of the resin layer (X) from which water has been removed).

5. In the peak intensity F detected by time-of-flight secondary ion mass spectrometry on the surface of the resin layer (X), the peak intensity of the negative ion fragment showing the maximum intensity is defined as M, and the negative ion (F) derived from elemental fluorine is defined as F. １７- 4. The laminated film according to claim 1, wherein Ff / M is less than 0.010, where Ff is the peak intensity of the peak intensity of the cross-linked polymer.

6. The peak intensity M of the positive ion fragment exhibiting the maximum intensity among the peak intensities F detected by time-of-flight secondary ion mass spectrometry on the surface of the resin layer (X) ＋ or the peak intensity M of the negative ion fragment showing the maximum intensity － 4. The laminate film according to claim 2 or 3, wherein Fh / M is 0.001 or more and 0.500 or less, where M is the maximum peak intensity and Fh is the total peak intensity of the fragments derived from the compound (A).

7. A laminated film according to any one of claims 1 to 3, wherein the PFAS (perfluoroalkyl and polyfluoroalkyl substances) content in the resin layer (X) is 50 ppm or less.

8. The laminated film according to claim 2 or 3, wherein the compound (A) is a surfactant having an HLB value of 10 or more and 18 or less.

9. The laminate film according to any one of claims 1 to 3, wherein the resin layer (X) contains a polyester resin (B) that satisfies the following characteristics: (B-1) contains at least a sulfo group in the side chain, and (B-2) has a conjugated cyclic structure in the main chain.

10. A laminated film according to any one of claims 1 to 3, wherein the resin layer contains at least one compound (C) selected from acrylic resins, urethane resins, epoxy resins, oxazoline compounds, and carbodiimide compounds.

11. The laminated film according to any one of claims 1 to 3, wherein the base resin contains at least one of biomass raw materials and recycled raw materials.

12. The laminated film according to any one of claims 1 to 3, which is used as a display film or a packaging film.

13. A laminate film according to any one of claims 1 to 3, having a processing layer (Y) containing at least one of a hard coating agent, an adhesive, and a printing ink on the surface of at least one of the resin layers (X) opposite to the surface having the base resin.

14. A display member or packaging material comprising the laminate of claim 13.

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