Heat sealable laminate film

Abstract

To provide a heat sealable laminate film which has a characteristic that at least one surface of the laminate film is hard to slip, prevents load collapse of a product, has excellent antifogging properties and opening easiness, and is excellent in processing characteristics in printing processing and laminate processing.SOLUTION: A heat sealable laminate film comprises at least a polyethylene terephthalate layer / a printed layer / a sealant layer. The heat sealable laminate film is such that: the polyethylene terephthalate layer is a biaxially stretched polyester film having at least an A layer and a B layer; the A layer and the B layer include polyethylene terephthalate resin as the main constituents; and the sealant layer is constituted by two or more layers including a substrate layer having polyethylene terephthalate as the main constituent, and a heat seal layer including an antifogging agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-sealable laminated film that is used in the packaging fields of foods, medicines, industrial products, etc., and that combines easy-open properties with anti-fogging properties. [Background technology]

[0002] Aromatic polyester films, such as polyethylene terephthalate (PET) film, are widely used as food and beverage containers. For example, in containers with snap-on lids, they are used to package soups, salads, raw vegetables, and other foods, taking advantage of their excellent transparency and airtightness. When packaging foods such as salads and raw vegetables, moisture from the vegetables can cause the inside of the container to fog up, so anti-fogging properties are essential.

[0003] Patent Document 1 discloses a packaging container that is manufactured by thermoforming a container body and a lid body coated with an anti-fogging agent using vacuum and compressed air forming, and then bonding the container body and the lid body together by heat sealing.

[0004] In recent years, there has been a trend toward top-sealed lids for the purposes of easier opening, standardization of lid materials (mono-material), and reduction of waste through thickness reduction. Top-sealed lids, like those with interlocking lids, are required to have airtightness, anti-fogging properties, and ease of opening. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-14295 Summary of the Invention [Problem to be solved by the invention]

[0006] With the shift to top-sealing lid materials, it has become impossible to form a groove that matches the shape of the fitting lid, and when plastic containers are stacked and displayed so that the bottom and top seal material are in contact, the containers may slip and collapse. Therefore, the object of the present invention is to provide a heat-sealable laminate film that has non-slip properties on at least one surface of the laminate film, prevents products from collapsing, has good anti-fogging properties and easy-opening properties, and has excellent processability in printing and laminating processes. [Means for solving the problem]

[0007] The present invention comprises the following components. [1] A heat-sealable laminate film comprising at least a polyethylene terephthalate layer / printed layer / sealant layer, wherein the polyethylene terephthalate layer is a biaxially oriented polyester film having at least Layer A and Layer B, wherein Layer A and Layer B contain polyethylene terephthalate resin as a main component, Layer A is located on the side opposite the printed layer, and Layer B is located on the printed layer side, and satisfies the following (a) and (b); the sealant layer is composed of two or more layers including a base layer whose main component is polyethylene terephthalate and a heat-seal layer containing an anti-fogging agent, wherein the base layer is located on the printed layer side and the heat-seal layer is located on the side opposite the printed layer, and the sealant layer satisfies the following (c) and (d). (a) The coefficient of dynamic friction when the surface of Layer A constituting the polyethylene terephthalate layer in the heat-sealable laminate film is brought into contact with a metal plate is 0.20 to 1.00. (b) The lubricant content in Layer A of the polyethylene terephthalate layer is 0 to 400 mass ppm, and the lubricant content in Layer B is 500 to 4,500 mass ppm. (c) A heat seal layer containing an anti-fog agent is heat sealed to an unstretched polyethylene terephthalate sheet at 0.2 MPa for 1 second at temperatures of 120°C, 140°C, 160°C, and 180°C, and the heat seal strength measured using a 15 mm wide test piece is 2.0 N / 15 mm or more and 12.0 N / 15 mm or less. (d) Under conditions of 5°C and 50% RH, 1 μL of distilled water is dropped onto at least one surface of the heat seal layer containing the anti-fogging agent, and the water contact angle measured after 5 seconds is 50° or less. [2] The heat-sealable laminate film according to [1], wherein the puncture strength of the polyethylene terephthalate layer is 0.60 to 1.00 N / μm. [3] The heat-sealable laminate film according to [1], wherein the ratio of the thickness of layer A to the thickness of the polyethylene terephthalate layer is 30 to 90%. [4] The heat-sealable laminate film according to [1], wherein the polyethylene terephthalate layer has an intermediate layer between the A layer and the B layer, the intermediate layer containing 60 to 100% by mass of a polyethylene terephthalate resin. [5] The heat-sealable laminate film according to [1], wherein the substrate layer constituting the sealant layer is a biaxially oriented polyester film. [6] The heat-sealable laminate film according to [1], wherein the thickness of the heat-sealable layer containing the anti-fogging agent in the sealant layer is 0.3 μm or more and 3.0 μm or less. [7] The heat-sealable laminate film according to [1], wherein the heat-sealable layer containing the anti-fogging agent in the sealant layer is composed of at least two or more polyester resins, and at least one of the polyester resins (C) has a glass transition temperature of 0°C or higher and 40°C or lower, and at least one of the polyester resins (D) has a glass transition temperature of 41°C or higher and 80°C or lower. [8] The heat-sealable laminate film according to [7], characterized in that the mass ratio of the polyester resins (C) and (D) constituting the heat-sealable layer containing the anti-fogging agent in the sealant layer is (C):(D) = 95:5 to 50:50. [9] 8. The heat-sealable laminate film according to claim 7, wherein the solids mass ratio of the total mass of the polyester resins (C) and (D) in the heat-sealable layer containing the anti-fogging agent in the sealant layer to the mass of the anti-fogging agent is 99:1 to 80:20.

[10] A package comprising the heat-sealable laminate film according to any one of [1] to [9].

[11] A top seal material for a container, comprising the heat-sealable laminate film according to any one of [1] to [9]. [Effects of the Invention]

[0008] According to the present invention, it is possible to obtain a heat-sealable laminate film having excellent non-slip properties, anti-fogging properties, easy-open properties, and processability in printing and laminating on at least one surface of the laminate film. In particular, by using the heat-sealable laminate film of the present invention as a material for packaging bags or a top seal material for plastic containers, it is possible to prevent products from slipping and collapsing when stacked and displayed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the laminate structure of the heat-sealable laminate film of the present invention. [Figure 2] 1 is a schematic diagram of the shape of an A-PET container used to evaluate the ease of opening in each example. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0011] The heat-sealable laminate film of the present invention preferably comprises at least a polyethylene terephthalate layer / printed layer / sealant layer, the sealant layer being composed of two or more layers including a substrate layer primarily composed of polyethylene terephthalate and a heat-seal layer containing an anti-fogging agent, the substrate layer being located on the printed layer side and the heat-seal layer being located opposite the printed layer side, and the polyethylene terephthalate layer being a biaxially oriented polyester film having a layer A with a relatively low lubricant content and a layer B with a high lubricant content, both of which contain polyethylene terephthalate resin as the primary component, the layer A being located opposite the printed layer side and the layer B being located on the printed layer side. For example, the laminate structure of the heat-sealable laminate film of the present invention is as shown in Figure 1, which shows an adhesive layer between the printed layer and the substrate layer constituting the sealant layer.

[0012] (Polyethylene terephthalate layer) The polyethylene terephthalate layer in the heat-sealable laminate film of the present invention is preferably a biaxially stretched polyester film, and preferably has at least Layer A and Layer B having different lubricant contents. It may have a two-layer structure consisting of Layer A and Layer B, or a three-layer or more structure including one or more intermediate layers between Layer A and Layer B.

[0013] [A layer] Layer A of the polyethylene terephthalate layer of the present invention contains polyethylene terephthalate resin (hereinafter sometimes referred to as PET resin) (a) as a raw material and as a main constituent component. Here, "containing as a main constituent component" means that the PET resin content is 60% by mass or more, more preferably 70% by mass or more, and most preferably 80% by mass or more. By making it 60% by mass or more, the transparency of the obtained laminated film becomes good, making it suitable for use in printing and also advantageous in terms of cost. Layer A may contain 100% by mass of PET resin (a).

[0014] The resin composition constituting layer A may contain a polyester resin (b) other than the PET resin (a) in order to adjust the mechanical properties of the polyethylene terephthalate layer. Examples of the polyester resin (b) other than the PET resin (a) include polyester resins such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polypropylene terephthalate (PPT), as well as polyester resins copolymerized with dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, and sebacic acid, and polyester resins copolymerized with diol components such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

[0015] The ratio of the thickness of Layer A to the thickness of the polyethylene terephthalate layer is preferably 30 to 90%. When the thickness ratio of Layer A is 30% or more, the surface on the Layer A side has non-slip properties, which is preferable because it is possible to prevent the collapse of the cargo of goods. On the other hand, when the thickness of Layer A is 90% or less, it is preferable because it is possible to improve the winding quality of the roll. More preferably, it is 35% to 80%.

[0016] The lower limit of the intrinsic viscosity of the resin composition constituting Layer A is preferably 0.45 dL / g, more preferably 0.50 dL / g, and most preferably 0.55 dL / g. By setting it to 0.45 dL / g or more, the intrinsic viscosity of the resulting biaxially oriented polyester film can be maintained high, and mechanical properties such as puncture strength can be improved. The upper limit of the intrinsic viscosity of the resin composition constituting Layer A is preferably 0.80 dL / g, more preferably 0.75 dL / g, and most preferably 0.70 dL / g. By setting it to 0.80 dL / g or less, excessive stress during film stretching can be prevented, and good film formability can be obtained.

[0017] The resin composition constituting Layer A may contain no lubricant other than the polyester resin, or may contain a lubricant to the extent that the slipperiness of the surface of Layer A can be controlled. The content of the lubricant contained in the resin composition constituting Layer A is preferably 0 to 400 ppm by mass, more preferably 0 to 380 ppm by mass, and even more preferably 0 to 350 ppm by mass. By keeping the content at 400 ppm by mass or less, slipperiness of the film surface can be imparted.

[0018] The lubricant can adjust the dynamic friction coefficient of the film, and examples thereof include inorganic lubricants such as silica, calcium carbonate, and alumina, as well as organic lubricants. Silica and calcium carbonate are preferred, and silica is the most preferred from the viewpoint of achieving both transparency and lubricity. However, as mentioned above, it does not necessarily have to be contained.

[0019] When the resin composition constituting Layer A contains a lubricant, the average particle size of the lubricant may be the same as or different from that of Layer B or the intermediate layer.

[0020] When the lubricant is contained, the average particle size of the lubricant is preferably 0.5 μm or more, more preferably 0.8 μm or more, and even more preferably 1.5 μm or more, while the average particle size of the lubricant is preferably 4.0 μm or less, more preferably 3.8 μm or less, and even more preferably 3.5 μm or less.

[0021] When the lubricant is contained, the pore volume of the lubricant is preferably 1.0 ml / g or more, more preferably 1.1 ml / g or more, and even more preferably 1.2 ml / g or more, while the pore volume of the lubricant is preferably 1.7 ml / g or less, more preferably 1.6 ml / g or less, and even more preferably 1.5 ml / g or less.

[0022] Layer A constituting the polyethylene terephthalate layer in the present invention may contain additives such as stabilizers, colorants, antioxidants, antistatic agents, and ultraviolet absorbers in addition to the polyester resin composition and lubricant.

[0023] [B layer] Layer B, which constitutes the polyethylene terephthalate layer in the present invention, contains PET resin (a) as a raw material and as a main constituent component. Here, "containing PET resin as a main constituent component" means that the PET resin content is 60% by mass or more, more preferably 70% by mass or more, and most preferably 80% by mass or more. By making it 60% by mass or more, the transparency of the obtained laminated film becomes good, making it suitable for use in printing and also advantageous in terms of cost. As an upper limit, all except for the mass of the lubricant may be PET resin (a).

[0024] The resin composition constituting layer B may contain a polyester resin (b) other than the PET resin (a) in order to adjust the mechanical properties of the biaxially stretched polyester film. Examples of the polyester resin (b) other than the PET resin (a) include polyester resins such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polypropylene terephthalate (PPT), as well as polyester resins copolymerized with dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, and sebacic acid, and polyester resins copolymerized with diol components such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

[0025] The lower limit of the intrinsic viscosity of the resin composition constituting Layer B is preferably 0.45 dL / g, more preferably 0.50 dL / g, and most preferably 0.55 dL / g. By setting it to 0.45 dL / g or more, the intrinsic viscosity of the resulting biaxially oriented polyester film can be maintained high, and mechanical properties such as puncture strength can be improved. The upper limit of the intrinsic viscosity of the resin composition constituting Layer B is preferably 0.80 dL / g, more preferably 0.75 dL / g, and most preferably 0.70 dL / g. By setting it to 0.80 dL / g or less, excessive stress during film stretching can be prevented, and good film formability can be obtained.

[0026] The polyester resin contained in the resin composition constituting the B layer may be the same as or different from that of the A layer.

[0027] In addition to the polyester resin, the resin composition constituting Layer B preferably contains a lubricant to improve the transportability of the film during printing and lamination. The content of the lubricant contained in the resin composition constituting Layer B is preferably 500 to 4,500 ppm by mass, more preferably 600 to 3,500 ppm by mass, and even more preferably 800 to 2,500 ppm by mass. By setting the lubricant content to 500 ppm by mass or more, the transportability of the film can be improved, and the processing suitability can be improved. On the other hand, by setting the lubricant content to 4,500 ppm by mass or less, the transparency of the film can be improved.

[0028] The lubricant can adjust the dynamic friction coefficient of the film, and examples thereof include inorganic lubricants such as silica, calcium carbonate, alumina, etc., as well as organic lubricants. Silica and calcium carbonate are preferred, and silica is most preferred from the viewpoint of achieving both transparency and lubricity.

[0029] The average particle size of the lubricant contained in the resin composition constituting the B layer may be the same as or different from that of the A layer or the B layer.

[0030] The average particle size of the lubricant is preferably 0.5 μm or more, more preferably 0.8 μm or more, and even more preferably 1.5 μm or more. When the particle size is 0.5 μm or more, irregularities can be formed on the surface of Layer B of the biaxially oriented polyester film. Therefore, slipperiness can be imparted to Layer B of the biaxially oriented polyester film. In addition, when the biaxially oriented polyester film is wound into a roll, blocking with Layer A can be suppressed, improving the winding quality of the roll. Meanwhile, the average particle size of the lubricant is preferably 4.0 μm or less, more preferably 3.8 μm or less, and even more preferably 3.5 μm or less. When the particle size is 4.0 μm or less, the formation of coarse protrusions on the surface of Layer B of the biaxially oriented polyester film can be prevented.

[0031] The pore volume of the lubricant is preferably 1.0 ml / g or more, more preferably 1.1 ml / g or more, and even more preferably 1.2 ml / g or more, while the pore volume of the lubricant is preferably 1.7 ml / g or less, more preferably 1.6 ml / g or less, and even more preferably 1.5 ml / g or less.

[0032] Layer B constituting the polyethylene terephthalate layer in the present invention may contain additives such as stabilizers, colorants, antioxidants, antistatic agents, and ultraviolet absorbers in addition to the polyester resin composition and lubricant.

[0033] [Middle layer] The polyethylene terephthalate layer in the present invention may have an intermediate layer between Layer A and Layer B, if necessary. The intermediate layer contains PET resin (a) as a raw material as a main constituent. Here, "containing PET resin as a main constituent" means that the content of PET resin is 60% by mass or more, more preferably 70% by mass or more, and most preferably 80% by mass or more. The upper limit is 100% by mass.

[0034] The resin composition constituting the intermediate layer may contain a polyester resin (b) other than the PET resin (a) in order to adjust the mechanical properties of the polyethylene terephthalate layer. Examples of the polyester resin (b) other than the PET resin (a) include polyester resins such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polypropylene terephthalate (PPT), as well as polyester resins copolymerized with dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, and sebacic acid, and polyester resins copolymerized with diol components such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

[0035] The lower limit of the intrinsic viscosity of the resin composition constituting the intermediate layer is preferably 0.45 dL / g, more preferably 0.50 dL / g, and most preferably 0.55 dL / g. By setting it to 0.45 dL / g or more, the intrinsic viscosity of the resulting biaxially oriented polyester film can be maintained high, and mechanical properties such as puncture strength can be improved. The upper limit of the intrinsic viscosity of the resin composition constituting the intermediate layer is preferably 0.80 dL / g, more preferably 0.75 dL / g, and most preferably 0.70 dL / g. By setting it to 0.80 dL / g or less, excessive stress during film stretching can be prevented, and good film formability can be obtained.

[0036] The polyester resin contained in the resin composition constituting the intermediate layer may be the same as or different from that of the A layer or the B layer.

[0037] The resin composition constituting the intermediate layer may contain no lubricant other than the polyester resin, or may contain a lubricant to improve the slipperiness of the film and improve the winding quality of the roll. The content of the lubricant contained in the resin composition constituting the intermediate layer is preferably 0 to 2,500 ppm by mass, more preferably 0 to 2,000 ppm by mass, and even more preferably 0 to 1,500 ppm by mass. However, since a high silica content may impair the transparency of the film, the total amount of lubricant contained in Layer A, Layer B, and the intermediate layer is preferably 4,500 ppm by mass or less, more preferably 3,500 ppm by mass or less, and even more preferably 2,500 ppm by mass or less, relative to the total polyethylene terephthalate layer.

[0038] The lubricant can adjust the dynamic friction coefficient of the film, and examples thereof include inorganic lubricants such as silica, calcium carbonate, alumina, and organic lubricants. Silica and calcium carbonate are preferred, and silica is the most preferred from the viewpoint of achieving both transparency and lubricity.

[0039] When the lubricant is contained, the average particle size of the lubricant is preferably 0.5 μm or more, more preferably 0.8 μm or more, and even more preferably 1.5 μm or more, while the average particle size of the lubricant is preferably 4.0 μm or less, more preferably 3.8 μm or less, and even more preferably 3.5 μm or less.

[0040] When the lubricant is contained, the pore volume of the lubricant is preferably 1.0 ml / g or more, more preferably 1.1 ml / g or more, and even more preferably 1.2 ml / g or more, while the pore volume of the lubricant is preferably 1.7 ml / g or less, more preferably 1.6 ml / g or less, and even more preferably 1.5 ml / g or less.

[0041] The intermediate layer may contain additives such as a stabilizer, a colorant, an antioxidant, an antistatic agent, and an ultraviolet absorber in addition to the polyester resin composition and lubricant.

[0042] The polyethylene terephthalate layer of the present invention may have a printed layer laminated on the surface of Layer B. Aqueous and solvent-based resin-containing printing inks are preferably used as the printing ink for forming the printed layer. Examples of resins used in printing inks include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, light-blocking agents, UV absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, antifoaming agents, crosslinking agents, antiblocking agents, and antioxidants.

[0043] The printing method for providing the printed layer is not particularly limited, and known printing methods such as offset printing, gravure printing, screen printing, etc. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying, infrared drying, etc. can be used.

[0044] Layer B constituting the polyethylene terephthalate layer in the present invention may be subjected to a smoothing corona discharge treatment, a glow discharge treatment, a flame treatment, or a surface roughening treatment, as long as the purpose of the present invention is not impaired, and may also be subjected to a known anchor coat treatment, printing, decoration, etc.

[0045] Layer B constituting the polyethylene terephthalate layer in the present invention may be laminated with a layer of another material, and as a method for this, the layer may be laminated after the laminate film is produced, or may be laminated during film production.

[0046] (Physical properties of polyethylene terephthalate layer) The thickness of the polyethylene terephthalate layer in the present invention is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more. By making it 3 μm or more, the strength of the film can be maintained. The upper limit of the thickness is preferably 100 μm or less, preferably 75 μm or less, and even more preferably 50 μm or less. By making it 100 μm or less, processing for the purpose of the present invention is facilitated.

[0047] The puncture strength of the polyethylene terephthalate layer in the present invention is preferably 0.60 N / μm or more, more preferably 0.62 N / μm or more, and even more preferably 0.64 N / μm or more. By setting it to 0.60 N / μm or more, for example, when the biaxially oriented polyester film is used as a lid material for plastic containers for food use, it can be used suitably without breaking even when external stress is applied to the lid material. The upper limit of the puncture strength is preferably 1.00 N / μm or less, more preferably 0.97 N / μm or less, and even more preferably 0.94 N / μm or less. Setting it to 1.00 N / μm or less can suppress thermal shrinkage, thereby reducing processing problems caused by film shrinkage in processes such as vapor deposition and printing.

[0048] The haze of the polyethylene terephthalate layer in the present invention is preferably 4.5% / 12 μm or less, more preferably 4.3% / 12 μm or less, and even more preferably 4.0% / 12 μm or less. By setting the haze to 4.5% / 12 μm or less, transparency is high and, for example, when the laminate film is used as a lid material for a plastic container or a packaging material, the contents can be clearly seen, and prints can be clearly seen, resulting in a good appearance.

[0049] The polyethylene terephthalate layer in the present invention preferably has a dry heat shrinkage rate at 150°C in the machine direction (hereinafter sometimes referred to as MD direction) and width direction (hereinafter sometimes referred to as TD direction) of 0.1 to 2.5%, more preferably 0.2 to 2.0%, and even more preferably 0.3 to 1.8%. By keeping the dry heat shrinkage rate at 2.5% or less, dimensional changes when heated in the secondary processing step can be suppressed, and the occurrence of wrinkles can be reduced.

[0050] The coefficient of dynamic friction when the surface of Layer A constituting the polyethylene terephthalate layer of the present invention is brought into contact with a metal plate and slid against it is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. The upper limit of the coefficient of dynamic friction is preferably 1.00 or less, more preferably 0.80 or less, and even more preferably 0.60 or less. By making it 0.20 or more, the film has excellent surface slip resistance. For example, when used as a lid material for plastic containers, even when the plastic containers are stacked and displayed so that the bottom of the container is in contact with Layer A, the containers are less likely to collapse due to slippage. A coefficient of 1.00 or less is preferable from the viewpoint of winding property during production of the polyethylene terephthalate layer.

[0051] (Method of manufacturing polyethylene terephthalate layer) While there are no particular limitations on the method for obtaining the polyethylene terephthalate layer of the present invention, the T-die method is preferred from the viewpoint of thickness accuracy. In the inflation method, the stretching ratio is difficult to increase due to the manufacturing method, which can result in thickness defects in the width direction. Here, a typical manufacturing process for the T-die method is described. The T-die method includes: (1) a step of melt-extruding a polyester resin composition into a sheet and cooling it on a cooling roll to form an unstretched sheet; (2) a step of stretching the formed unstretched sheet in the MD direction and the TD direction perpendicular to the MD direction; (3) a heat-setting step of heating and crystallizing the film after the stretching; (4) a heat-relaxing step (sometimes referred to as a relaxation step) of removing residual strain in the heat-set film; and (5) a cooling step of cooling the film after the heat-relaxing step. In step (1), a so-called co-extrusion process is preferably used, in which raw materials for forming Layer A, Layer B, and, if necessary, the intermediate layer are melt-extruded from separate extruders.

[0052] The upper limit of the resin melting temperature in the extruder is preferably 310°C, more preferably 300°C. If the temperature is 300°C or lower, decomposition of the resin can be suppressed, preventing the film from becoming brittle and also preventing deterioration of film quality due to heat degradation products. The lower limit of the resin melting temperature in the extruder is preferably 230°C, more preferably 240°C. If the temperature is 230°C or higher, not only can the resin be extruded, but discharge is stable and thickness accuracy is good.

[0053] The upper limit of the chill roll temperature is preferably 40°C, and more preferably 20°C or lower. If the temperature is 40°C or lower, the crystallinity of the molten polyester resin composition will not be too high when it is cooled and solidified, making it easier to stretch, and also suppressing a decrease in transparency due to crystallization. The lower limit of the chill roll temperature is preferably 0°C. If the temperature is 0°C or higher, the effect of suppressing crystallization when the molten polyester resin composition is cooled and solidified can be fully exerted. Furthermore, when the chill roll temperature is in the above range, it is preferable to reduce the humidity of the environment near the chill roll to prevent condensation.

[0054] The thickness of the unstretched sheet is preferably in the range of 15 to 2500 μm, more preferably 500 μm or less, and most preferably 300 μm or less.

[0055] The stretching method will now be described. The stretching method can be either simultaneous biaxial stretching or sequential biaxial stretching, but in order to increase the piercing strength, it is necessary to increase the degree of planar orientation, and in this respect sequential biaxial stretching is preferred.

[0056] The lower limit of the MD stretching temperature is preferably 90°C, more preferably 95°C, and particularly preferably 100°C. A temperature of 90°C or higher is preferred because breakage can be further suppressed. The upper limit of the MD stretching temperature is preferably 140°C, more preferably 135°C, and particularly preferably 130°C. A temperature of 140°C or lower is preferred because the degree of planar orientation can be increased and the puncture strength can be increased.

[0057] The lower limit of the MD stretching ratio is preferably 2.8 times, more preferably 2.9 times, and particularly preferably 3.0 times. A ratio of 2.8 times or more is preferable because it can increase the degree of planar orientation and improve puncture strength. Furthermore, a ratio of 2.8 times or more can suppress thickness unevenness and prevent slack in the film roll. The upper limit of the MD stretching ratio is preferably 4.5 times, more preferably 4.4 times, and particularly preferably 4.3 times. A ratio of 4.5 times or less is preferable because it can sufficiently improve mechanical strength and thickness unevenness.

[0058] The lower limit of the TD stretching temperature is preferably 100°C, more preferably 105°C, and particularly preferably 110°C. A temperature of 100°C or higher is preferable because it can make breakage less likely to occur. The upper limit of the TD stretching temperature is preferably 140°C, more preferably 135°C, and particularly preferably 130°C. A temperature of 140°C or lower is preferable because it can increase the degree of planar orientation and improve puncture strength.

[0059] The lower limit of the stretching ratio in the TD direction is preferably 3.8 times, more preferably 3.9 times, and particularly preferably 4.0 times. A stretching ratio of 3.8 times or more is preferable because it can increase the degree of planar orientation and improve puncture strength. The upper limit of the stretching ratio in the TD direction is preferably 5.0 times, more preferably 4.9 times, and particularly preferably 4.8 times. A stretching ratio of 5.0 times or less is preferable because it can sufficiently improve mechanical strength and thickness unevenness.

[0060] The lower limit of the heat setting temperature is preferably 170°C, more preferably 180°C, and particularly preferably 190°C. A temperature of 170°C or higher is preferable because it can further reduce the heat shrinkage rate. The upper limit of the heat setting temperature is preferably 240°C, more preferably 230°C, and particularly preferably 220°C. A temperature of 240°C or lower is preferable because it can prevent the film from melting, increase the degree of planar orientation, and increase the puncture strength.

[0061] The lower limit of the relaxation rate is preferably 0.5%, more preferably 1.0%, and particularly preferably 2.0%. A rate of 0.5% or more is preferable because the thermal shrinkage rate in the TD direction can be kept low. The upper limit of the relaxation rate is preferably 10%, more preferably 8%, and particularly preferably 6%. A rate of 10% or less is preferable because it can prevent slack and improve flatness.

[0062] (sealant layer) [Heat seal layer containing anti-fogging agent] The heat seal layer containing an antifogging agent that constitutes the sealant layer of the present invention preferably contains at least the following polyester resin (C), polyester resin (D), and antifogging agent (E) components. The inclusion of polyester resin (C) and polyester resin (D) components not only allows for excellent easy-open properties, a wide sealing temperature range, and blocking resistance, but also allows for excellent antifogging properties to be achieved by the inclusion of antifogging agent (E). Furthermore, an antiblocking agent (F) may also be added to improve blocking resistance.

[0063] The polyester resin (C) and the polyester resin (D) are preferably polyesters having a chemical structure obtained by polycondensation of a carboxylic acid component consisting of a divalent or higher polycarboxylic acid compound and an alcohol component consisting of a divalent or higher polyalcohol compound. In the case of polyesters having a chemical structure obtained by polycondensation of a carboxylic acid component consisting of a divalent or higher polycarboxylic acid compound and an alcohol component consisting of a divalent or higher polyalcohol compound, it is preferable that at least one of the polycarboxylic acid compound and the polyalcohol compound is a copolymerized polyester resin consisting of two or more components. Furthermore, the polycarboxylic acid compound and the polyalcohol compound are preferably copolymerized polyester resins consisting mainly of dicarboxylic acid components and glycol components. Here, "mainly" refers to a situation in which the total of all acid components and all alcohol components constituting the polyester resin (C) used in the present invention is 200 mol %, and the total of the dicarboxylic acid components and glycol components accounts for 100 mol % or more on a molar basis.

[0064] As the dicarboxylic acid, aromatic dicarboxylic acids or aliphatic dicarboxylic acids are preferred, and aromatic dicarboxylic acids are more preferred. When the total amount of carboxylic acid components is taken as 100 mol%, the lower limit of the copolymerization amount of the aromatic dicarboxylic acid component is preferably 40 mol%, more preferably 45 mol%, and particularly preferably 50 mol%. By making it 40 mol% or more, the glass transition temperature (Tg) can be kept low.

[0065] Specific examples of aromatic dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid. Specific examples of aliphatic dicarboxylic acids include, but are not limited to, succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These dicarboxylic acids can be used alone or in combination of two or more. Other polycarboxylic acid components that can be used include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-(hydroxyethoxy)benzoic acid, unsaturated alicyclic dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid, hexahydrophthalic acid, and tetrahydrophthalic acid, and alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. Furthermore, tricarboxylic and tetracarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid, and their anhydrides, may also be included as needed.

[0066] The glycol component is preferably an aliphatic glycol. When the total amount of glycol components is taken as 100 mol%, the lower limit of the copolymerization amount of the aliphatic glycol component is preferably 70 mol%, more preferably 75 mol%, and particularly preferably 80 mol%. By making it 70 mol% or more, Tg can be kept low.

[0067] Specific examples of aliphatic glycols include, but are not limited to, ethylene glycol, propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These glycol components can be used alone or in combination of two or more. Other glycol components that can be used include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanediol, ethylene oxide and propylene oxide adducts of bisphenol A, and ethylene oxide and propylene oxide adducts of hydrogenated bisphenol A. In addition to these, small amounts of triols and tetraols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol may be contained, if necessary.

[0068] The lower limit of the glass transition temperature of the polyester resin (C) is preferably 0°C, more preferably 5°C, and particularly preferably 10°C. A temperature of 0°C or higher is preferred because it provides good blocking resistance. The upper limit of the glass transition temperature of the polyester resin (C) is preferably 40°C, more preferably 35°C, and particularly preferably 30°C. A temperature of 40°C or lower is preferred because it allows the heat seal strength to fall within the range claimed and provides easy opening.

[0069] The lower limit of the reduced viscosity (ηsp / c) of the polyester resin (C) is preferably 0.2 dL / g, more preferably 0.4 dL / g, and particularly preferably 0.6 dL / g. A reduced viscosity of 0.2 dL / g or more is preferred because it allows the resin cohesive force to be exerted and improves heat seal strength. The upper limit of the reduced viscosity (ηsp / c) of the polyester resin (C) is preferably 1.5 dL / g, more preferably 1.3 dL / g. A reduced viscosity of 1.5 dL / g or less is preferred because it reduces the likelihood of unevenness during coating.

[0070] The lower limit of the number average molecular weight (Mn) of the polyester resin (C) is preferably 5,000, more preferably 10,000, and particularly preferably 15,000. By making it 5,000 or more, the resin cohesive force is exerted and heat seal strength is exerted. The upper limit of the number average molecular weight (Mn) of the polyester resin (C) is preferably 40,000, more preferably 35,000. A molecular weight of 40,000 or less is preferred because it prevents the viscosity of the coating solution from increasing when it is prepared, making it less likely for unevenness to occur during coating.

[0071] The lower limit of the glass transition temperature of the polyester resin (D) is preferably 41°C, more preferably 46°C, and particularly preferably 51°C. By setting it to 41°C or higher, the heat seal strength can be within the range claimed and easy opening can be achieved, which is preferable. The upper limit of the glass transition temperature of the polyester resin (D) is preferably 80°C, more preferably 75°C, and particularly preferably 60°C. By setting it to 80°C or lower, the heat seal strength can be within the range claimed and easy opening can be achieved, which is preferable.

[0072] The lower limit of the reduced viscosity (ηsp / c) of the polyester resin (D) is preferably 0.1 dl / g, more preferably 0.2 dl / g, and particularly preferably 0.3 dl / g. By making it 0.1 dl / g or more, the resin cohesive force is exerted and heat seal strength is exerted. The upper limit of the reduced viscosity (ηsp / c) of the polyester resin (D) is preferably 1.3 dl / g, more preferably 1.0 dl / g. A reduced viscosity of 1.3 dl / g or less is preferred because unevenness during coating is less likely to occur.

[0073] The lower limit of the number average molecular weight (Mn) of the polyester resin (D) is preferably 2000, more preferably 5000, and particularly preferably 10000. By making it 2000 or more, the resin cohesive force is exerted and heat seal strength is exerted. The upper limit of the number average molecular weight (Mn) of the polyester resin (C) is preferably 25000, more preferably 20000. A molecular weight of 25000 or less is preferred because it prevents the viscosity of the coating solution from increasing when it is prepared, making it less likely for unevenness to occur during coating.

[0074] Blending at least two polyester resins with different glass transition temperatures is preferred because it provides consistent heat seal strength over a wide temperature range from 120°C to 180°C and exhibits easy-open properties. The mechanism by which blending polyester resins with different glass transition temperatures exhibits the aforementioned easy-open properties is believed to be due to selective cohesive failure occurring in the anti-fog layer during heat seal strength measurement. It is generally believed that failure progresses from the weakest point in terms of mechanical strength during heat seal strength measurement. In the anti-fog layer of the laminate film of the present invention, the polyester resin (D) with a high glass transition temperature exhibits high heat seal strength with the seal surface, while the polyester resin (C) with a low glass transition temperature is thought to reduce the mechanical strength of the anti-fog layer, or in other words, to exhibit brittleness. Therefore, in terms of mechanical strength, the high heat seal strength with the seal surface exceeds the brittleness of the anti-fog layer, resulting in selective cohesive failure occurring in the anti-fog layer, which has the weakest mechanical strength. Therefore, in the present invention, by mixing at least two polyester resins with different glass transition temperatures, cohesive failure can be selectively caused in the anti-fogging layer regardless of the heat sealing temperature, thereby making it possible to achieve easy-open properties over a wide temperature range.

[0075] The lower limit of the mass ratio of polyester resin (C) to polyester resin (D) is preferably polyester resin (C):polyester resin (D)=50:50 mass%, more preferably 45:55 mass%, and particularly preferably 60:40 mass%. By setting the mass ratio of polyester resin (C) to 50 mass% or more, the anti-fog layer can be made brittle, the heat seal strength can be within the claimed range over a wide temperature range, and easy opening is achieved, which is preferable. The upper limit of the mass ratio of polyester resin (C) to polyester resin (D) is preferably polyester resin (C):polyester resin (D)=95:5 mass%, more preferably 85:15 mass%, and particularly preferably 80:20 mass%. By setting the mass ratio of polyester resin (C) to 95 mass% or less, the seal strength of the seal surface can be increased, the heat seal strength can be within the claimed range over a wide temperature range, and easy opening can be achieved, which is preferable.

[0076] The antifogging agent (E) is not particularly limited as long as it imparts antifogging properties, and for example, anionic surfactants, nonionic surfactants, cationic surfactants, or amphoteric surfactants can be used. Of these, it is preferable to use nonionic surfactants.

[0077] For example, anionic surfactants include sulfate ester salts of higher alcohols, higher alkyl sulfonates, higher carboxylates, alkylbenzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, and vinyl sulfosuccinate salts. Nonionic surfactants include compounds having a polyoxyethylene structure, such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol fatty acid esters, ethylene oxide-propylene oxide block copolymers, polyoxyethylene fatty acid amides, and ethylene oxide-propylene oxide copolymers, as well as sorbitan derivatives. Cationic surfactants include alkylamine salts, dialkylamine salts, trialkylamine salts, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, and alkylbenzalkonium chloride. Amphoteric surfactants include lauryl betaine and lauryldimethylamine oxide.

[0078] Specific examples of nonionic surfactants include sorbitan surfactants such as sorbitan monostearate, sorbitan distearate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan monobehenate, sorbitan dibehenate, sorbitan monolaurate, and sorbitan dilaurate; glycerin surfactants such as glycerin monolaurate, glycerin dilaurate, diglycerin monopalmitate, diglycerin dipalmitate, glycerin monostearate, glycerin distearate, diglycerin monostearate, diglycerin distearate, diglycerin monolaurate, and diglycerin dilaurate; polyethylene glycol monostearate, polyethylene glycol Examples include polyethylene glycol surfactants such as glycerol monopalmitate, trimethylolpropane surfactants such as trimethylolpropane monostearate, diethanolalkylamine and diethanolalkylamide surfactants such as lauryl diethanolamine, oleyl diethanolamine, stearyl diethanolamine, lauryl diethanolamide, oleyl diethanolamide, and stearyl diethanolamide, pentaerythritol surfactants such as pentaerythritol monopalmitate, and polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan distearate, and mono- and distearates of sorbitan-diglycerin condensates. These can be used alone or in combination of two or more.

[0079] Specific examples of cationic surfactants include amine salts such as laurylamine acetate, triethanolamine monoformate, and stearamidoethyl diethylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, dilauryldimethylammonium chloride, distearyldimethylammonium chloride, lauryldimethylbenzylammonium chloride, and stearyldimethylbenzylammonium chloride. These can be used alone or in combination of two or more.

[0080] The lower limit of the hydrophilic-lipophilic balance (hereinafter abbreviated as HLB) value of the antifogging agent (E) is preferably 3, more preferably 4, and particularly preferably 5. When the HLB value is 3 or more, antifogging properties are exhibited. The upper limit of the HLB value of the antifogging agent (E) is preferably 10, more preferably 9, and particularly preferably 8. By setting the HLB value to 10 or less, it is possible to prevent the antifogging agent from depositing excessively on the film surface, and to prevent the haze from worsening and the seal strength from decreasing.

[0081] The content of the antifogging agent (E) in the heat seal layer containing the antilayer agent has a lower limit of preferably 1.0 mass%, more preferably 1.5 mass%, and particularly preferably 2.0 mass% in terms of solid content concentration. When the content is 1.0 mass% or more, antifogging properties are exhibited. The upper limit is preferably 10.0% by mass, more preferably 9.5% by mass, and particularly preferably 9.0% by mass. By setting the content to 10.0% by mass or less, the haze is good and a decrease in heat seal strength due to excessive precipitation of the anti-fog agent on the surface can be suppressed.

[0082] The heat seal layer containing the antifogging agent of the present invention may contain an antiblocking agent (F). Examples of antiblocking agents include inorganic particles, organic particles, waxes, etc., and can be contained to a degree that does not reduce heat seal strength. These antiblocking agents can be used alone or in combination of two or more. The lower limit of the content of the antiblocking agent, calculated as the solids concentration of the heat seal layer containing the antifogging agent, is preferably 0.1% by mass or more, more preferably 0.3% by mass, and particularly preferably 0.5% by mass. A content of 0.1% by mass or more exhibits blocking resistance. The upper limit of the content of the antiblocking agent, calculated as the solids concentration of the heat seal layer containing the antifogging agent, is preferably 5.0% by mass or less, more preferably 4.5% by mass, and particularly preferably 4.0% by mass. A content of 5.0% by mass or less does not impair heat seal strength.

[0083] Examples of inorganic particles include inorganic particles containing metal oxides, hydroxides, sulfates, carbonates, or silicates of, for example, magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, or titanium. Among these inorganic particles, silica gel particles are particularly preferred. The particle shape may be any shape, such as powder, particle, granule, plate, or needle shape.

[0084] Examples of organic particles include polymer particles such as polymethyl methacrylate resin, polystyrene resin, nylon resin, melamine resin, benzoguanamine resin, phenol resin, urea resin, silicone resin, methacrylate resin, or acrylate resin, as well as cellulose powder, nitrocellulose powder, wood powder, waste paper powder, starch, etc. The shape of the particles may be any shape, such as powder, particle, granule, plate, or needle shape.

[0085] Specific examples of waxes include hydrocarbon waxes such as liquid paraffin, natural paraffin, microwax, synthetic paraffin, and polyethylene wax; fatty acid waxes such as stearic acid; fatty acid amide waxes such as stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylene bisstearamide, oleic acid amide, and esylic acid amide; ester waxes such as lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, and fatty acid polyglycol esters; alcohol waxes such as cetyl alcohol and stearyl alcohol; olefin waxes; natural waxes such as castor wax and carnauba wax; and metal soaps derived from fatty acids having 12 to 30 carbon atoms.

[0086] The heat seal layer containing the antifogging agent is laminated on at least one side of the substrate layer. The lamination method can be coextrusion with the resin composition constituting the substrate layer, dry lamination of the substrate layer and the heat seal layer containing the antifogging agent, extrusion coating of the antifogging layer onto the substrate layer, or solvent coating of the substrate layer. Preferably, the laminate film of the present invention can be obtained by coating (applying) an organic solvent solution of the resin composition constituting the antifogging layer onto the substrate layer and drying it.

[0087] [Base material layer] The substrate layer constituting the sealant layer in the present invention is preferably composed primarily of polyethylene terephthalate. That is, the substrate layer preferably contains at least 60% by mass of polyethylene terephthalate. The substrate layer is preferably a biaxially oriented polyester film for the purpose of improving the impact resistance of the laminated film. Unstretched polyester films have poor impact resistance due to their manufacturing method, and the film may be damaged by external impacts or the load caused by stacking products when displayed. Furthermore, unstretched polyester films are prone to significant thickness unevenness due to their manufacturing method, making them prone to blocking when rolled. The manufacturing method for biaxially oriented polyester films is not particularly limited, and both simultaneous biaxial stretching and sequential biaxial stretching are possible. However, inflation methods are undesirable because they tend to cause thickness unevenness due to their manufacturing method and prone to blocking when rolled.

[0088] The main component of the base layer constituting the sealant layer in the present invention is not particularly limited as long as it is a polyester, but polyethylene terephthalate is preferably used as the main component. Other polyesters may also be included as long as they do not impair the present invention. Specific examples include polyester resins such as polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polypropylene terephthalate; polyester resins copolymerized with dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, and sebacic acid; and polyester resins copolymerized with diol components such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate diol.

[0089] In order to improve the lubricity of the sealant layer in the present invention, inorganic lubricants such as titanium dioxide, fine particle silica, kaolin, calcium carbonate, etc., or organic lubricants such as long-chain fatty acid esters, etc. may be added. Furthermore, colorants, antistatic agents, ultraviolet absorbers, etc. may also be added as necessary.

[0090] The layer structure of the substrate layer constituting the sealant layer in the present invention is not particularly limited, and may be a single layer structure, a two-layer structure, a three-layer structure, a four-layer structure, or an ultra-multilayer structure. In addition, each layer may have a different composition.

[0091] (Sealant layer properties) The lower limit of the thickness of the heat seal layer containing the antifogging agent is preferably 0.3 μm or more, more preferably 0.5 μm or more, and particularly preferably 0.7 μm or more. When it is 0.3 μm or more, heat sealability is exhibited. The upper limit of the thickness of the heat seal layer containing the antifogging agent is preferably 3.0 μm or less, more preferably 2.8 μm or less, and particularly preferably 2.6 μm or less. When it is 3.0 μm or less, blocking resistance is good.

[0092] The upper limit of the haze of the sealant layer of the present invention is preferably 10% or less, more preferably 8%, and particularly preferably 6%. When the haze is 10% or less, transparency is high when used as a lid material, and the contents can be sufficiently seen, which is preferable.

[0093] In the present invention, the heat seal layer containing an anti-fogging agent that constitutes the sealant layer of the heat sealable laminate film is preferably located as the outermost layer. The water contact angle of the heat seal layer in the present invention is measured at a temperature of 5°C and a relative humidity of 50% (50% RH). A-PET containers that package foods such as salads are usually stored and displayed under refrigerated conditions, making anti-fogging properties important. Therefore, a water contact angle at 5°C is more suitable than general room temperature conditions for accurately representing anti-fogging properties under refrigerated conditions.

[0094] The upper limit of the water contact angle of the heat seal layer containing the antifogging agent of the present invention is preferably 50°, more preferably 40°, and particularly preferably 30°. By setting it to 50° or less, even if water vapor dispersed from the contents or the like adheres to the laminated film, the water droplets can be spread thinly, and the appearance does not become cloudy, which is preferable. The lower limit of the water contact angle of the heat seal layer containing the antifogging agent of the present invention is preferably 10°, more preferably 15°, and particularly preferably 20°. By setting it to 10° or more, it is possible to prevent excessive deposition of the antifogging agent on the surface, which would reduce the heat seal strength, which is preferable.

[0095] When the impact strength of the sealant layer of the present invention is measured from the base layer side, the lower limit is 0.5 J, more preferably 0.6 J, and particularly preferably 0.8 J. By setting the impact strength to 0.5 J or more, the container has sufficient strength to withstand external stress during transportation and display, and can prevent the lid material from breaking. By setting the impact strength to 0.5 J or more, the orientation of the laminated film can be suppressed isotropically, and easy opening can be achieved.

[0096] The lower limit of the heat seal strength when the heat-sealable laminate film of the present invention and an unstretched polyethylene terephthalate sheet having a thickness of 200 μm are heat-sealed at temperatures of 120° C., 140° C., 160° C., and 180° C. is preferably 2 N / 15 mm, more preferably 3 N / 15 mm, and particularly preferably 4 N / 15 mm. A strength of 2 N / 15 mm or more is preferable because it provides sufficient sealing strength when used as a lid material.

[0097] The upper limit of the heat seal strength when the heat seal layer containing the antifogging agent constituting the sealant layer of the heat sealable laminate film of the present invention and a 200 μm unstretched polyethylene terephthalate sheet are heat sealed at temperatures of 120° C., 140° C., 160° C., and 180° C. is preferably 12 N / 15 mm, more preferably 11 N / 15 mm, and particularly preferably 10 N / 15 mm. By setting the upper limit to 12 N / 15 mm, when used as a lid material, the seal strength is not too strong and a great force is not required to open it, and the laminate film can be prevented from tearing due to the seal strength being too strong, which is preferable.

[0098] In the present invention, when the heat-sealable laminate film is used as a lid material for an A-PET container, it is preferable to intentionally cause cohesive failure within the heat-seal layer containing the anti-fogging agent when the lid material is opened, thereby obtaining a consistent heat-seal strength over a wide temperature range.

[0099] [Method of manufacturing base layer] The method for obtaining the substrate layer is not particularly limited, but the T-die method is preferred from the viewpoint of good thickness accuracy, while the inflation method is prone to thickness unevenness due to its manufacturing method.

[0100] The upper limit of the cooling roll temperature is preferably 40° C., more preferably 20° C. or less. When the temperature is 40° C. or less, the crystallinity of the molten polyester resin composition does not become too high when it is cooled and solidified, which is preferable because stretching is easy.

[0101] The base layer is preferably a biaxially oriented polyester film. The lower limit of the stretching temperature in the longitudinal direction (also referred to as MD direction) is preferably 90°C, more preferably 95°C, and particularly preferably 100°C. A temperature of 90°C or higher is preferred because breakage can be suppressed. The upper limit of the stretching temperature in the MD direction is preferably 140°C, more preferably 135°C, and particularly preferably 130°C. A temperature of 140°C or lower is preferred because it can sufficiently increase the orientation of molecular chains and improve the impact strength of the film after biaxial orientation.

[0102] The lower limit of the stretching ratio in the MD direction is preferably 3.0 times, more preferably 3.2 times, and particularly preferably 3.4 times. A stretching ratio of 3.0 times or more is preferable because it improves thickness unevenness and blocking resistance. The upper limit of the stretching ratio in the MD direction is preferably 4.0 times, more preferably 3.8 times, and particularly preferably 3.6 times. A stretching ratio of 4.0 times or less is preferable because it can suppress breakage.

[0103] The lower limit of the stretching temperature in the width direction (also referred to as the TD direction) is preferably 100°C, more preferably 105°C, and particularly preferably 110°C. A temperature of 100°C or higher is preferred because breakage can be suppressed. The upper limit of the stretching temperature in the TD direction is preferably 140°C, more preferably 135°C, and particularly preferably 130°C. A temperature of 140°C or lower is preferred because it can sufficiently increase the orientation of molecular chains and improve the impact strength of the film after biaxial orientation.

[0104] The lower limit of the stretching ratio in the TD direction is preferably 3.5 times, more preferably 3.6 times, and particularly preferably 3.7 times. A stretching ratio of 3.5 times or more is preferable because it improves thickness unevenness and blocking resistance. The upper limit of the stretching ratio in the MD direction is preferably 4.5 times, more preferably 4.4 times, and particularly preferably 4.3 times. A stretching ratio of 4.5 times or less is preferable because it can suppress breakage.

[0105] The lower limit of the heat setting temperature is preferably 180°C, more preferably 190°C, and particularly preferably 200°C. A temperature of 180°C or higher is preferable because it can reduce the heat shrinkage rate. The upper limit of the heat setting temperature is preferably 240°C, more preferably 230°C, and particularly preferably 220°C. A temperature of 240°C or lower is preferable because it can prevent a decrease in impact strength.

[0106] The lower limit of the relaxation rate is preferably 0.5%, more preferably 1.0%, and particularly preferably 2.0%. A rate of 0.5% or more is preferable because the thermal shrinkage rate can be kept low. The upper limit of the relaxation rate is preferably 10%, more preferably 8%, and particularly preferably 6%. Setting the rate to 10% or less is preferable because it can prevent slack and blocking when rolled.

[0107] The lower limit of the thickness of the substrate layer of the present invention is preferably 5 μm, more preferably 10 μm, and particularly preferably 15 μm. Having a thickness of 5 μm or more is preferable because impact strength and tear strength can be maintained. The upper limit of the thickness of the substrate layer of the present invention is preferably 100 μm, more preferably 80 μm, and particularly preferably 50 μm. Having a thickness of 100 μm or less is preferable because it can be suitably used as a lid material.

[0108] [Heat-sealable laminated film]

[0109] The heat-sealable laminate film of the present invention is suitable for use as a packaging material. In particular, it is suitable as a lid material for food packaging containers. When used as a lid material for a food packaging container, it is preferable that the anti-fogging layer surface of the laminate film contacts the opening edge of the food packaging container to form a seal. The food packaging container using the laminate film of the present invention as a lid material is not particularly limited, but is preferably a polyester-based container, and particularly preferably an A-PET (amorphous polyethylene terephthalate) container.

[0110] The heat-sealable laminate film of the present invention comprises a polyethylene terephthalate layer and a sealant layer, but the laminate film can also be constructed by interposing an adhesive layer, a printed layer, a metal layer, etc. between the polyethylene terephthalate layer and the sealant layer. The lamination is usually performed by extrusion lamination or dry lamination.

[0111] The heat-sealable laminate film of the present invention can be used in the packaging fields of foods, medicines, industrial products, etc., and can form packages. In particular, it can be suitably used as a top seal material for packaging containers. In this case, it is preferable to use it so that the surface of Layer A becomes the outer surface of the top seal material. The layer configuration of the top seal material for packaging containers, where the layer boundary is represented by / , can be, for example, a non-slip surface layer (i.e., a polyethylene terephthalate layer including Layer A as the outermost layer) / sealant layer, a non-slip surface layer / gas barrier layer / protective layer, a non-slip surface layer / gas barrier layer / protective layer / adhesive layer / sealant layer, a non-slip surface layer / gas barrier layer / protective layer / adhesive layer / resin layer / adhesive layer / sealant layer, a non-slip surface layer / adhesive layer / resin layer / gas barrier layer / protective layer / adhesive layer / sealant layer, a non-slip surface layer / gas barrier layer / protective layer / printing layer / adhesive layer / sealant layer, or a non-slip surface layer / printing layer. / gas barrier layer / protective layer / adhesive layer / sealant layer, surface non-slip layer / gas barrier layer / protective layer / adhesive layer / resin layer / printing layer / adhesive layer / sealant layer, surface non-slip layer / adhesive layer / resin layer / printing layer / gas barrier layer / protective layer / adhesive layer / sealant layer, surface non-slip layer / printing layer / gas barrier layer / protective layer / adhesive layer / resin layer / adhesive layer / sealant layer, surface non-slip layer / printing layer / adhesive layer / resin layer / gas barrier layer / protective layer / adhesive layer / sealant layer, surface non-slip ...printing layer / adhesive layer / sealant layer, etc. [Example]

[0112] (Method for evaluating polyethylene terephthalate layer) The film was evaluated by the following measurement methods. Unless otherwise specified, measurements were carried out in a measurement room at 23°C and a relative humidity of 65%.

[0113] [Thickness of polyethylene terephthalate layer] Measurement was carried out using a dial gauge in accordance with JIS K7130 (1999) Method A.

[0114] [Puncture strength of polyethylene terephthalate layer] The values ​​measured using a test method conforming to JIS Z1707 (2019) were converted to 1 μm using the following formula. Puncture strength (N / μm) = Measured puncture strength value / Film thickness

[0115] [Haze of polyethylene terephthalate layer] According to JIS K7136 (2000), the film was cut into a square with a side length of 10 cm, and the haze was measured using a haze meter NDH8000 manufactured by Nippon Denshoku Co., Ltd. Measurements were taken at three locations, and the average value was used as the actual haze measurement value. The haze converted to 12 μm was calculated using the following formula. Haze (% / 12μm) = measured haze value x 12 / film thickness

[0116] [Heat shrinkage rate of polyethylene terephthalate layer] The thermal shrinkage rate was measured using a dimensional change test method in accordance with JIS C2151 (2019), except that the test temperature was 150°C and the heating time was 15 minutes.

[0117] (Method for evaluating sealant layer) [Base layer thickness] The thickness of the substrate layer before laminating the antifogging agent was measured using an electronic micrometer Millitron 1202D manufactured by Seiko EM Corporation.

[0118] [Thickness of heat seal layer containing anti-fogging agent] The thickness of the laminated film (base layer + heat seal layer containing anti-fog agent) was measured using a Millitron 1202D electronic micrometer manufactured by Seiko EM Corporation. The anti-fog layer side of the laminated film was then completely wiped off with a solvent in which the anti-fog layer is soluble. The thickness of the wiped sample was also measured in the same way, and the thickness of the heat seal layer containing the anti-fog agent was calculated using the following formula (2). Formula (2) Anti-fog layer thickness (μm) = Laminated film thickness (μm) - Film thickness after wiping (μm)

[0119] [Haze of sealant layer] According to JIS K7361-1, the laminated film was cut into a square shape with a side of 10 cm, and the haze was measured using a haze meter NDH8000 manufactured by Nippon Denshoku Co., Ltd. Measurement was carried out at six locations, and the average value was taken as the actual haze measurement value.

[0120] [Water contact angle] The water contact angle of the heat seal layer surface containing the anti-fog agent in the sealant layer was measured using a contact angle meter "Portable Contact Angle Meter PCA-1 (Kyowa Interface Science Co., Ltd.)" under conditions of 5°C and 50% RH. A 1 μL drop of water was applied per measurement, and the angle between the anti-fog layer and the water drop was read 5 seconds after application. The θ / 2 method was used to measure the water contact angle, and 10 water contact angles were measured per sample, with the average value being used as the contact angle for that sample.

[0121] [Impact strength] Using an impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the strength of the sealant layer against impact punching from the substrate layer side was measured under conditions of 5°C and 50% RH. An impact sphere with a diameter of 1.2 inches was used.

[0122] (Method for evaluating heat-sealable laminated films) [Dynamic friction coefficient between the surface of the polyethylene terephthalate layer on the A side and the metal plate] In accordance with JIS K-7125, a tensile tester (A&D Tensilon RTG-1210) was used to measure the coefficient of dynamic friction by contacting the surface of Layer A of the film with a metal plate in an environment of 23°C and 65% RH. SUS304 (2B) was used as the metal plate. The mass of the sled (weight) around which the upper film was wrapped was 3.5 kg, and the size of the base area of ​​the sled was 39.7 mm. 2 The pulling speed when measuring the friction coefficient was 200 mm / min. In the examples and tables, this is referred to as "dynamic friction coefficient (layer A / metal plate)".

[0123] [Average particle size of lubricant] HORIBA LA-750 Particle Size Analyzer The particle size corresponding to 50 mass percent was measured using a particle size analyzer. The reading was taken as the average particle size.

[0124] [Lubricant pore volume] The BET nitrogen adsorption isotherm was measured using AS-1 manufactured by Quantachrome Co., Ltd., and the pore volume was determined. Specifically, the pore volume was determined when the relative pressure P / P0 was 0.98.

[0125] [Transportability of polyethylene terephthalate layer] Gravure printing was carried out. The film roll of the polyethylene terephthalate layer was attached to the unwinding section of the printing machine, and the film was transported to the gravure roll to print the entire B layer. The transport suitability was evaluated as follows. 〇: No problems with transportability ×: Film transport is poor, resulting in poor processability

[0126] [Evaluation of slope slippage] The surface of Layer A of the heat-sealable laminate film was brought into contact with the bottom of a plastic container, a load was applied to the plastic container, and the angle when the container was placed on a flat surface was set to 0°. The angle of inclination (°) was measured at a rate of 2° / min, when the container began to slide. The plastic container used and the load used during measurement are listed below. Polystyrene lunch box (PS container) length 230mm x width 195mm x height 25mm (manufactured by Fukusuke Kogyo Co., Ltd.), load 200g Polypropylene tray container ("PP container"), length 190mm x width 140mm x height 31mm (manufactured by Chuo Chemical Co., Ltd.), load 200g A-PET clean cup container ("A-PET container"), diameter φ101 mm x height 35 mm (manufactured by Rispack Co., Ltd.), load 100 g The angle at which the container began to slide was evaluated according to the following criteria. ○: The sliding angle is 26° or more ×: The sliding angle is less than 26°

[0127] [Heat seal strength] A 200 μm-thick unstretched polyethylene terephthalate sheet was stacked on the heat-sealable laminate film, with the heat-seal layer containing the anti-fogging agent. The sample was then bonded using a heat sealer. The heat-sealing conditions were an upper bar temperature of 120°C to 180°C in 20°C increments, a lower bar temperature of 30°C, a pressure of 0.2 MPa, and a time of 1 second. Heat-sealed samples were cut out to a seal width of 15 mm. Heat-seal strength was measured using a tensile tester "AGS-KNX" (Shimadzu Corporation) with a sample chuck distance of 20 mm and a tensile speed of 200 mm / min. Heat-seal strength is expressed as the strength per 15 mm of seal width (N / 15 mm).

[0128] [Anti-fogging rating] A 30cm x 30cm square sample was cut from the heat-sealable laminate film. 300mL of 50°C hot water was poured into a plastic container (500mL capacity, approximately 10cm diameter at the mouth). The sample was then used to cover the mouth of the plastic container, with the heat-sealable layer containing the anti-fogging agent facing the hot water. This was used as an evaluation sample. The mouth was sealed with a rubber band. After leaving this evaluation sample at 5°C for 30 minutes, the water droplets adhering to the lid were visually evaluated according to the following criteria. Judgment: Yes. Cloudiness due to water droplets is less than 1 / 4 of the total area of ​​the mouth. Determining the result: The cloudiness caused by water droplets is more than 1 / 4 of the total area of ​​the mouth.

[0129] [Easy to open] The heat-sealable laminate film was placed on the heat-sealable layer containing the anti-fogging agent on an A-PET container of the shape and size shown in Figure 2, and the heat-sealable laminate film was heat-sealed from above. The heat-sealing conditions were temperatures of 120°C, 140°C, 160°C, and 180°C, a pressure of 0.2 MPa, and a time of 1 second. The laminate film was then peeled by hand, and the ease of peeling was evaluated based on the following tactile sensation. Rating A: Sufficiently adhered and easily removable by hand Rating B: The adhesive was insufficient and could be peeled off without much force. Rating C: The adhesive is too strong and cannot be easily removed by hand. Rating D: The film was torn when opened.

[0130] [Manufacturing Example 1] <Preparation of polyethylene terephthalate layer> (Polyethylene terephthalate layer 1)

[0131] The resin composition constituting Layer A was PET resin (terephthalic acid / ethylene glycol = 100 / / 100 (mol%), inherent viscosity 0.62 dL / g, no silica particles added). The resin composition constituting the intermediate layer was PET resin (terephthalic acid / ethylene glycol = 100 / / 100 (mol%), inherent viscosity 0.62 dL / g, no silica particles added) (the raw materials for Layer A and the intermediate layer were the same). The resin composition constituting Layer B was PET resin (terephthalic acid / ethylene glycol = 100 / / 100 (mol%), inherent viscosity 0.62 dL / g, silica particles added). Except for the inclusion of silica particles, the composition was the same as Layer A and the intermediate layer. Silica particles used were Sylysia 310 (average particle size 2.7 μm, pore volume 1.60 ml / g) manufactured by Fuji Silysia Corporation.

[0132] Using an apparatus consisting of three extruders and a 380 mm wide co-extrusion T-die, the above two resin compositions were melted at 280°C, then laminated in a configuration of A layer / intermediate layer / B layer using the feed block method, cast from the T-die at 280°C, and adhered to a 10°C cooling roll using an electrostatic adhesion method to obtain an unstretched sheet. The unstretched sheet was then stretched 3.5 times in the MD direction at 115°C, then passed through a tenter and stretched 4.0 times in the TD direction at 120°C, followed by heat setting at 215°C for 3 seconds and relaxation at 7% for 1 second. The surface of Layer B was then corona treated to obtain a 12 μm-thick biaxially oriented polyester film (polyethylene terephthalate layer 1). The physical properties and evaluation results of the resulting film are shown in Table 1.

[0133] (Polyethylene terephthalate layers 2 to 8) Biaxially oriented polyester films (polyethylene terephthalate layers 2 to 8) having a thickness of 12 μm were obtained by film formation in the same manner as for surface substrate 1, except that the content of silica particles contained in the resin compositions constituting Layer A, the intermediate layer, and Layer B, and the layer ratio of Layer A / Intermediate layer / Layer B were changed as shown in Table 1. The silica particles used for polyethylene terephthalate layer 5 were Sylysia 420 (average particle size 3.1 μm, pore volume 1.25 ml / g) manufactured by Fuji Silysia Ltd. The physical properties and evaluation results of the obtained polyethylene terephthalate are shown in Table 1.

[0134] [Table 1]

[0135] [Manufacturing Example 2] <Creating a sealant layer> (Synthesis example of polyester resins (C) and (D) for heat seal layer containing anti-fogging agent) (Polyester C-1) Dimethyl terephthalate, dimethyl isophthalate, dimethyl sebacate, ethylene glycol, and 2,2-dimethyl-1,3-propanediol were charged into an esterification reactor in the molar fractions (mol%) listed in Table 2. The temperature was raised to 230°C, and the transesterification reaction was carried out over 4 hours. After the transesterification reaction, the system was heated to 250°C, the pressure was reduced to 10 torr over 60 minutes, and the polycondensation reaction was carried out at 250°C for 60 minutes. Nitrogen was then introduced into the system, and the vacuum was broken to terminate the polycondensation reaction. After the reaction, the polyester resin was removed and cooled to obtain polyester C-1. The glass transition temperature was 7°C.

[0136] (Polyester C-2) Dimethyl terephthalate, dimethyl sebacate, ethylene glycol, and propylene glycol were charged into an esterification reactor in the molar fractions (mol%) shown in Table 2, and the temperature was raised to 230°C while the transesterification reaction was carried out over 4 hours. After the transesterification reaction was completed, the pressure in the system was raised to 250°C while reducing the pressure to 10 torr over 60 minutes, and the polycondensation reaction was carried out at 250°C for 60 minutes. Nitrogen was then introduced into the system, and the vacuum was broken to terminate the polycondensation reaction. After the reaction was completed, the polyester resin was removed and cooled to obtain polyester C-2. The glass transition temperature was 16°C.

[0137] (Polyester C-3) Dimethyl terephthalate, dimethyl isophthalate, dimethyl sebacate, ethylene glycol, and 2,2-dimethyl-1,3-propanediol were charged into an esterification reactor in the molar fractions (mol%) listed in Table 2. The temperature was raised to 230°C, and the transesterification reaction was carried out over 4 hours. After the transesterification reaction, the system was heated to 250°C, the pressure was reduced to 10 torr over 60 minutes, and the polycondensation reaction was carried out at 250°C for 60 minutes. Nitrogen was then introduced into the system, and the vacuum was broken to terminate the polycondensation reaction. After the reaction, the polyester resin was removed and cooled to obtain polyester C-3. The glass transition temperature was 32°C.

[0138] (Polyester D-1) Dimethyl terephthalate, dimethyl isophthalate, dimethyl sebacate, ethylene glycol, and propylene glycol were charged into an esterification reactor in the molar fractions (mol%) shown in Table 2, and the temperature was raised to 230°C while the transesterification reaction was carried out over 4 hours. After the transesterification reaction was completed, the system was heated to 250°C while the pressure was reduced to 10 torr over 60 minutes, and the polycondensation reaction was carried out at 250°C for 60 minutes. Nitrogen was then introduced into the system, and the vacuum was broken to terminate the polycondensation reaction. After the reaction was completed, the polyester resin was removed and cooled to obtain polyester D-1. The glass transition temperature was 47°C.

[0139] (Polyester D-2) Dimethyl terephthalate, dimethyl isophthalate, ethylene glycol, and 2,2-dimethyl-1,3-propanediol were charged into an esterification reactor in the molar fractions (mol%) listed in Table 2. The temperature was raised to 230°C, and the transesterification reaction was carried out over 4 hours. After the transesterification reaction, the pressure in the system was raised to 250°C, and the pressure was reduced to 10 torr over 60 minutes. The polycondensation reaction was then carried out at 250°C for 60 minutes. Nitrogen was then introduced into the system, and the vacuum was broken to terminate the polycondensation reaction. After the reaction, the polyester resin was removed and cooled to obtain polyester D-2. The glass transition temperature was 67°C.

[0140] Table 2 shows the composition and physical properties of each level of polyester resin (C) and (D).

[0141] [Table 2]

[0142] (Formation of substrate layer) The extruder was loaded with PET resin (terephthalic acid / ethylene glycol = 100 / / 100 (mol%), inherent viscosity 0.62 dl / g, silica particles blended at 0.1 mass% when the total resin composition was 100 mass%). The resin was melted at 280°C in the extruder, then cast from a T-die at 280°C and adhered to a cooling roll at 10°C by electrostatic adhesion to obtain an unstretched sheet. The unstretched sheet was then stretched 3.5 times in the longitudinal direction at a temperature of 115°C, and then passed through a tenter to stretch 4.0 times in the transverse direction at 115°C. Heat setting was performed at 220°C for 3 seconds and relaxation treatment was performed by 5% for 1 second to obtain a biaxially oriented polyester film (substrate layer) having a thickness of 25 μm.

[0143] (Sealant layer 1) Coating agent A was obtained by heating and stirring polyester C-1 [75% by mass], polyester D-2 [19% by mass], anti-fog agent E-1 (Rikemal L-71-D, nonionic surfactant, HLB 7.3, manufactured by Riken Vitamin Co., Ltd.) [5% by mass], and anti-blocking agent F (SYLOID C-812, amorphous silica, manufactured by GRACE Co., Ltd.) [1% by mass] in an ethyl acetate solution. The solids concentration was adjusted to 10% by mass. Coating agent A was applied to the biaxially oriented polyester film (substrate layer) using a wire bar coating method, dried at 90°C for 20 seconds, and a heat-seal layer containing the anti-fog agent was laminated, obtaining sealant layer 1. The heat-seal layer thickness was 1.5 μm.

[0144] (Sealant layers 2 to 16) Each sealant layer was obtained in the same manner as for Sealant Layer 1, except that the thickness of the anti-fogging layer and the coating agent composition were changed as shown in Table 4. A nonionic surfactant (Noigen ES-149D, HLB 11.5, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was used as anti-fogging agent E-2.

[0145] Table 3 shows the compositions (compositions of solid contents) of the coating agents (A) to (L) for forming a heat seal layer.

[0146] [Table 3]

[0147] Table 4 shows the structure and properties of each sealant layer obtained in Production Example 2.

[0148] [Table 4]

[0149] [Examples and Comparative Examples] <Preparation of heat-sealable laminated film> An ink manufactured by Toyo Ink Co., Ltd. was applied to the entire B layer of each polyethylene terephthalate layer obtained in Production Example 1. Furthermore, an ester-based adhesive obtained by mixing 33.6 parts by mass of a base agent (TM569 manufactured by Toyo Morton Co., Ltd.), 4.0 parts by mass of a curing agent (CAT10L manufactured by Toyo Morton Co., Ltd.), and 62.4 parts by mass of ethyl acetate was used to apply an ink in an amount of 3.0 g / m. 2 The ink-coated surface of the polyethylene terephthalate layer was coated with the ink so that the ink was applied, and the film was dry-laminated to the base layer side of each sealant layer obtained in Production Example 2. The film was wound up and kept at 40°C for 3 days, after which the heat-sealable laminate film was evaluated. The evaluation results are shown in Table 5.

[0150] [Table 5]

[0151] As shown in Table 5, the heat-sealable laminated films of the examples had good coefficient of dynamic friction against metal, inclined sliding, heat-seal strength, anti-fogging properties, and easy-open properties.

[0152] [Comparative Example 1] The same procedure as in Example 1 was carried out except that the amount of silica in Layer B was changed to the polyethylene terephthalate layer 6 shown in Table 1. The polyethylene terephthalate layer 6 had poor film transport suitability during printing, making it impossible to process, and no laminate was obtained.

[0153] Comparative Example 2 The same procedure as in Example 1 was carried out, except that the content of silica particles in Layer A was changed to polyethylene terephthalate Layer 7 shown in Table 1. The dynamic friction coefficient (Layer A / metal plate) was small, and slip resistance was lost. In addition, the start angle of inclined sliding was small for all plastic containers, and the results were poor.

[0154] Comparative Example 3 The same procedure as in Example 1 was carried out, except that the layer ratio of Layer A to Layer B was changed to 8 polyethylene terephthalate layers as shown in Table 1. Because Layer A was thin, the dynamic friction coefficient (Layer A / metal plate) was small, and slip resistance was lost. In addition, the start angle of inclined sliding was small for all plastic containers, resulting in poor performance.

[0155] Comparative Example 4 A laminated film was obtained in the same manner as in Example 1, except that the thickness of the heat seal layer containing the antifogging agent was changed to 0.2 μm. The obtained laminated film not only had a large water contact angle and poor antifogging properties, but also had weak heat seal strength, and was unable to be heat sealed during the evaluation of easy-open properties, resulting in poor results.

[0156] Comparative Example 5 A laminated film was obtained in the same manner as in Example 1, except that the thickness of the heat seal layer containing the antifogging agent was changed to 3.2 μm. The obtained laminated film had poor blocking resistance.

[0157] Comparative Example 6 Except for changing the coating agent composition of the heat seal layer containing the antifogging agent, a laminated film was obtained in the same manner as in Example 1. The obtained laminated film had high heat seal strength, but was difficult to open when evaluated for ease of opening, resulting in a poor result.

[0158] Comparative Example 7 Except for changing the coating agent composition of the heat seal layer containing the antifogging agent, a laminated film was obtained in the same manner as in Example 1. The obtained laminated film had poor heat seal strength and could not be heat sealed.

[0159] [Comparative Example 8] Except for changing the coating agent composition of the heat seal layer containing the antifogging agent, a laminated film was obtained in the same manner as in Example 1. The obtained laminated film had high heat seal strength, but was difficult to open when evaluated for ease of opening, resulting in a poor result.

[0160] Comparative Example 9 Except for changing the coating agent composition of the heat seal layer containing the antifogging agent, a laminated film was obtained in the same manner as in Example 1. The obtained laminated film had poor heat seal strength and could not be heat sealed.

[0161] [Comparative Example 10] A laminated film was obtained in the same manner as in Example 1, except that the coating agent composition of the heat seal layer containing the antifogging agent was changed to one not containing the antifogging agent. The obtained laminated film had a large water contact angle and poor antifogging properties.

[0162] [Comparative Example 11] Except for changing the coating agent composition of the heat seal layer containing the antifogging agent, a laminated film was obtained in the same manner as in Example 1. The obtained laminated film had poor heat seal strength and could not be heat sealed. [Industrial Applicability]

[0163] According to the present invention, it is possible to obtain a heat-sealable laminate film having at least one surface that is non-slip and that has excellent anti-fogging properties, easy-open properties, and processability in printing and laminating processes. By using the heat-sealable laminate film of the present invention as a material for packaging bags or a top seal material for plastic containers, it is possible to prevent products from slipping and collapsing when stacked and displayed. [Explanation of symbols]

[0164] 1: A layer 2: Middle class 3: B layer 4: Printing layer 5: Adhesive layer 6 : Base material layer 7: Heat seal layer 8: Polyethylene terephthalate layer 9: Sealant layer 10: Heat-sealable laminated film

Claims

1. A heat-sealable laminate film comprising at least a polyethylene terephthalate layer / printed layer / sealant layer, wherein the polyethylene terephthalate layer is a biaxially oriented polyester film having at least Layer A and Layer B, wherein Layer A and Layer B contain polyethylene terephthalate resin as a main component, Layer A is located on the side opposite to the printed layer side, and Layer B is located on the printed layer side, and satisfies the following (a) and (b); the sealant layer is composed of two or more layers including a base layer containing polyethylene terephthalate as a main component, and a heat-sealable layer containing an anti-fogging agent, wherein the base layer is located on the printed layer side and the heat-sealable layer is located on the side opposite to the printed layer side, and the sealant layer satisfies the following (c) and (d). (a) The coefficient of dynamic friction when the surface of Layer A constituting the polyethylene terephthalate layer in the heat-sealable laminate film is brought into contact with a metal plate is 0.20 to 1.

00. (b) The lubricant content in Layer A of the polyethylene terephthalate layer is 0 to 400 ppm by mass, and the lubricant content in Layer B is 500 to 4,500 ppm by mass. (c) A heat seal layer containing an anti-fogging agent and an unstretched polyethylene terephthalate sheet are heat-sealed at 0.2 MPa for 1 second at temperatures of 120°C, 140°C, 160°C, and 180°C, and the heat seal strength measured using a 15 mm wide test piece is 2.0 N / 15 mm or more and 12.0 N / 15 mm or less. (d) Under conditions of 5°C and 50% RH, 1 μL of distilled water is dropped onto at least one surface of the heat seal layer containing the anti-fogging agent, and the water contact angle measured after 5 seconds is 50° or less.

2. 2. The heat-sealable laminate film according to claim 1, wherein the puncture strength of the polyethylene terephthalate layer is 0.60 to 1.00 N / μm.

3. 2. The heat-sealable laminate film according to claim 1, wherein the thickness ratio of layer A to the polyethylene terephthalate layer is 30 to 90%.

4. 2. The heat-sealable laminate film according to claim 1, wherein the polyethylene terephthalate layer has an intermediate layer between the A layer and the B layer, the intermediate layer containing 60 to 100% by mass of a polyethylene terephthalate resin.

5. 2. The heat-sealable laminate film according to claim 1, wherein the base layer constituting the sealant layer is a biaxially oriented polyester film.

6. 2. The heat-sealable laminate film according to claim 1, wherein the thickness of the heat-sealable layer containing the anti-fogging agent in the sealant layer is 0.3 μm or more and 3.0 μm or less.

7. 2. The heat-sealable laminate film according to claim 1, wherein the heat-sealable layer containing the anti-fogging agent in the sealant layer contains at least two or more polyester resins, and at least one of the polyester resins (C) has a glass transition temperature of 0°C or higher and 40°C or lower, and at least one of the polyester resins (D) has a glass transition temperature of 41°C or higher and 80°C or lower.

8. The heat-sealable laminate film according to claim 7, characterized in that the mass ratio of the polyester resins (C) and (D) constituting the heat-sealable layer containing the anti-fogging agent in the sealant layer is (C):(D) = 95:5 to 50:

50.

9. 8. The heat-sealable laminate film according to claim 7, wherein the solids mass ratio of the total mass of the polyester resins (C) and (D) in the heat-sealable layer containing the anti-fogging agent in the sealant layer to the mass of the anti-fogging agent is 99:1 to 80:

20.

10. A package comprising the heat-sealable laminate film according to any one of claims 1 to 9.

11. A top seal material for a container, comprising the heat-sealable laminate film according to any one of claims 1 to 9.

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