Anti-fogging heat-sealable film and its applications

Abstract

To provide a heat-fusible film that has an anti-fogging coating layer on the surface of a film containing a heat-fusible polymer and in which anti-fogging property, heat seal strength (easy seal-open property), and low blocking property are balanced at a high level.SOLUTION: Provided is a heat-fusible film that has a coating layer containing (a) a low-molecular surfactant and (b) a high-molecular surfactant and in which the blending ratio of (a) the low-molecular surfactant and (b) the high-molecular surfactant is 95 / 5 to 5 / 95 on a mass basis, on the surface of a polymer film containing a heat-fusible polymer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a heat-sealable film that is preferably used for easy-open packaging and the like, and more specifically, to a heat-sealable film that has an excellent balance of anti-fogging properties, easy-open properties, and low blocking properties. [Background technology]

[0002] Polymer films are widely used for food packaging containers because of their excellent formability, safety, quality retention, and other properties. Water vapor from the contents may adhere to the surface of the lids of food packaging containers as water droplets. In this case, the contents (food) of the food packaging container may become invisible, or the food may deteriorate due to the falling of the water droplets. Therefore, anti-fogging agents are used to impart anti-fogging properties to polymer films of the lids of food packaging containers. When a polymer film is used as a lid material for a food packaging container, etc., a heat seal layer made of a soft polyester resin or the like can be provided on the surface of the polymer film in order to seal the container between the food packaging container body and the polymer film. Even in this case, anti-fogging properties are often required for the polymer film, and an anti-fogging agent is used, but in order to achieve excellent anti-fogging properties and appropriate heat seal strength (easy opening), it has been proposed to add an anti-fogging agent to the heat seal layer and intermediate layer, each of which is made of a specific material (see, for example, Patent Document 1).

[0003] Heat-sealable polymer films used as lids for food packaging containers are also required to suppress blocking during storage. From the viewpoint of productivity, it is desirable that the anti-fogging agent be applicable by coating. Therefore, there is a strong demand for a heat-sealable film that has an excellent balance of anti-fogging properties, heat seal strength (easy opening), and low blocking properties, and that can be coated with an anti-fogging coating.

[0004] [Patent Document 1] International Publication No. 2015 / 046132 A1 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above technical background, the present invention aims to provide a heat-sealable film having an anti-fog coating layer on a film surface containing a heat-sealable polymer, which has a high level of balance between anti-fog properties, heat seal strength (easy opening), and low blocking properties. [Means for solving the problem]

[0006] As a result of extensive research, the inventors have discovered that by applying a coating agent containing a specific blend ratio of a low molecular weight surfactant and a polymeric surfactant to a heat-sealable polymer film, it is possible to significantly improve the anti-fogging properties of the polymer film while maintaining the heat seal strength (easy opening property) and low blocking property of the polymer film, and have thus completed the present invention. That is, the present invention provides: [1] The present invention relates to a heat-sealable film having a coating layer on the surface of a polymer film containing a heat-sealable polymer, the coating layer containing (a) a low molecular weight surfactant and (b) a polymer surfactant, the blending ratio of the (a) low molecular weight surfactant to the (b) polymer surfactant being 95 / 5 to 5 / 95 by mass.

[0007] The following [2] to [8] are all preferred aspects or embodiments of the present invention. [2] (a) The heat-sealable film according to [1], wherein the low molecular weight surfactant includes a nonionic surfactant. [3] (b) The heat-sealable film according to [1] or [2], wherein the polymer surfactant contains an acrylic surfactant. [4] The coating amount of the coating agent is 0.2 g / m 2 The heat-sealable film according to any one of [1] to [3], which is: [5] The heat-sealable film according to any one of [1] to [4], wherein the heat-sealable polymer is polyethylene terephthalate. [6] An easy-open film comprising a heat-sealable layer (A) made of the heat-sealable film according to any one of [1] to [5], an intermediate layer (B), and a laminate layer (C) laminated in this order. [7] The easy-open film according to [6], wherein the intermediate layer (B) and / or the laminate layer (C) contain an ethylene-based polymer. [8] The easy-open film according to [6], wherein the intermediate layer (B) contains an acid-modified polyolefin. [9] An easy-open package comprising a lid material having the easy-open film according to any one of [6] to [8] and a container. Effect of the Invention

[0008] The heat-sealable film of the present invention combines highly practical properties, such as anti-fogging properties, heat seal strength (easy opening), and low blocking properties, at a level that exceeds the limits of conventional technology, and also has excellent productivity, so it can be suitably used in a variety of applications, including as a lid material for easily openable plastic containers for storing various products such as food that require visibility of the contents. [Brief description of the drawings]

[0009] [Figure 1] (a) is a schematic diagram of the evaluation criteria for anti-fogging properties, and (b) is a photograph of an actual anti-fogging evaluation example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention is a heat-sealable film, comprising a coating layer on the surface of a polymer film containing a heat-sealable polymer, the coating layer containing (a) a low molecular weight surfactant and (b) a polymer surfactant, the blending ratio of the (a) low molecular weight surfactant to the (b) polymer surfactant being 95 / 5 to 5 / 95 by mass. That is, the heat-sealable film of the present invention has as its components a polymer film containing a heat-sealable polymer and a coating layer, and the coating layer contains (a) a low molecular weight surfactant and (b) a polymer surfactant in a predetermined ratio.

[0011] Polymer Film The polymer film constituting the heat-sealable film of the present invention may contain a heat-sealable polymer, and the layer structure is not limited. Therefore, it may be a single-layer film consisting of only one layer containing a heat-sealable polymer (hereinafter, also referred to as "heat-sealable layer (A)"), or it may be a laminated film consisting of a layer containing a heat-sealable polymer and another layer. From the viewpoint of the degree of freedom in design taking into consideration the mechanical properties of the film and lamination with other films, it is preferable that the film is a laminated film having a heat-sealing layer (A) on the surface, which is laminated with other films having an intermediate layer (B), a lamination layer (C), etc. Such a laminated film can be preferably used as an easy-open film.

[0012] There is no particular limitation on the heat-fusible polymer contained in the polymer film constituting the present invention, and any polymer capable of imparting heat-fusible properties to the polymer film can be used as appropriate.

[0013] As the heat-fusible polymer, polyester-based resins such as amorphous polyester, polyethylene-based resins such as low-density polyethylene, and ethylene-α-olefin copolymers can be preferably used. When the composition is used as a lid material for polyethylene terephthalate (PET) containers such as amorphous polyethylene terephthalate, polyester resins can be particularly preferably used as the heat-fusible polymer.

[0014] The polyester resin is preferably amorphous or low crystalline. The polyester resin may comprise, as a dibasic acid component, a component selected from phthalic acid, terephthalic acid, isophthalic acid, adipic acid, sebacic acid, naphthalenedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid, and structural isomers thereof, dicarboxylic acids such as malonic acid, succinic acid, and adipic acid or derivatives thereof, p-hydroxybenzoic acid, p-hydroxybenzoic acid esters, and oxyacids such as glycolic acid or derivatives thereof, and ethylene glycol as a glycol component. and a component selected from aliphatic glycols such as bisphenol A, diethylene glycol, neopentyl glycol, hexanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and pentamethylene glycol, alicyclic glycols such as cyclohexanedimethanol, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S, one or more of which are selected from each of these components and combined to carry out an ester exchange reaction or esterification reaction between the dibasic acid component and the glycol component, followed by a melt polycondensation reaction, and the resultant product can be used.

[0015] In addition, as the polyester resin, a lactic acid polymer can also be used, and examples thereof include, but are not limited to, poly(D-lactic acid), poly(L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and other hydroxycarboxylic acid, a copolymer of L-lactic acid and other hydroxycarboxylic acid, or a blend of these, and a copolymer of a polyester component obtained by esterification of a dicarboxylic acid and a diol with a lactic acid component. Among these, polylactic acid whose main structural unit is L-lactic acid is particularly preferred from the viewpoint of film formation stability.

[0016] Examples of the hydroxycarboxylic acid, diol and dicarboxylic acid include hydroxycaproic acids such as glycolic acid, hydroxybutyric acid and hydroxycaproic acid, and cyclic lactones such as caprolactone, butyrolactone, lactide and glycolide; aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid; and aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid and sebacic acid.

[0017] As the polyester resin used in this embodiment, a non-crystalline copolymerized polyethylene terephthalate resin having a glass transition temperature Tg of about -20 to 90°C, preferably -15°C to 85°C, which is a combination of a dibasic acid component and a glycol component, is particularly suitable.

[0018] Heat-sealing layer (A) The heat-sealable layer (A) containing the above-mentioned fusible polymer can be placed on the packaging container body side and fused to the packaging container body, for example, when the heat-sealable film of the present invention is used as a lid material for a packaging container for food or the like. A coating layer having a low molecular weight surfactant and a high molecular weight surfactant in a weight ratio of 95 / 5 to 5 / 95 can be formed on the surface of the heat-sealing layer (A). In this embodiment, by combining the specific heat-sealing layer and the specific coating layer, a heat-sealing film having high practical value properties such as anti-fogging property, heat seal strength (easy opening property), and low blocking property at a high level exceeding the limits of conventional technology can be provided with high productivity.

[0019] The heat-sealing layer (A) may consist only of the heat-sealing polymer, or may be a mixture of the heat-sealing polymer with other resins, additives, etc. The content of the heat-sealing polymer in the heat-sealing layer (A) is preferably 50 to 99.9 mass%, more preferably 70 to 99.9 mass%, and particularly preferably 90 to 99.9 mass%.

[0020] In the heat-sealable layer (A), various additives and fillers other than the heat-sealable polymers may be added, such as heat stabilizers, antioxidants, light stabilizers, antistatic agents, antiblocking agents, lubricants, nucleating agents, flame retardants, pigments, dyes, calcium carbonate, barium sulfate, magnesium hydroxide, mica, talc, clay, antibacterial agents, antifogging agents, etc. Furthermore, other thermoplastic resins, thermoplastic elastomers, rubbers, hydrocarbon resins, petroleum resins, etc. may be blended in the range not contrary to the object of the present invention.

[0021] The heat-sealing layer (A) may contain an anti-fogging agent of the same kind or a different kind as that used in the specific coating layer, but care should be taken not to impair the function of the specific coating layer. As described later, it is preferable to use a polyolefin resin such as polyethylene for each layer such as the intermediate layer (B) and the laminate layer (C), and in this case, it is preferable to use a polyolefin resin such as polyethylene as the other thermoplastic resin from the viewpoint of lamination strength with each layer, etc. Furthermore, it is preferable that the intermediate layer (B) contains an acid-modified polyolefin resin from the viewpoint of adhesion with the heat-sealing layer (A), etc.

[0022] The thickness of the heat-sealing layer (A) is not particularly limited, but from the viewpoint of sealing property, etc., it is preferably 2 μm or more, and particularly preferably 3 μm or more. On the other hand, from the viewpoint of ease of opening, etc., the thickness is preferably 10 μm or less, and particularly preferably 8 μm or less.

[0023] The polymer film constituting the heat-sealable film of the present invention may be a single-layer film consisting of only one heat-sealable layer (A) as described above, but from the viewpoint of obtaining a film having desired performance by sharing the functions of multiple layers, it may also be a laminated film of the heat-sealable layer (A) and other layers. From the viewpoint of design freedom taking into consideration the mechanical properties of the film and lamination with other films, it is preferable that the film has a heat-sealing layer (A) on the surface, which is laminated with other layers such as an intermediate layer (B) and a laminate layer (C).

[0024] Middle layer (B) The components of the intermediate layer (B) constituting the heat-sealable film of this embodiment are not particularly limited, but from the viewpoints of the strength, transparency, light weight, etc. of the heat-sealable film, it is preferable that the intermediate layer (B) contains a polyolefin, and it is particularly preferable that the intermediate layer (B) contains an ethylene-based polymer. Furthermore, from the viewpoints of adhesion to the polyester preferably used in the heat-sealable layer (A), it is preferable that the intermediate layer (B) contains an acid-modified polyolefin-based resin, and it is even more preferable that the intermediate layer (B) contains an acid-modified polyethylene-based resin. Preferred examples of ethylene polymers include polyethylene resins such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), linear medium density polyethylene (LMDPE), medium density polyethylene (MDPE), and ethylene-vinyl acetate copolymer (EVA), which may be used alone or in combination of two or more. Among these, LLDPE is preferred because of its good film-forming properties. A preferred example of the acid-modified polyolefin is a modified polymer obtained by copolymerizing (e.g., graft-copolymerizing) a polyolefin with an unsaturated carboxylic acid or a derivative thereof. Examples of the polyolefin include homopolymers of olefins, mutual copolymers (between olefins), and copolymers with other copolymerizable monomers (e.g., other vinyl monomers). Specific examples include polyethylene (LDPE, LLDPE, etc.), polypropylene, polybutene, mutual copolymers thereof, ionomer resins, ethylene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, etc. Examples of the unsaturated carboxylic acid or a derivative thereof include unsaturated carboxylic acids such as maleic acid and fumaric acid, their acid anhydrides, their esters, or their metal salts. Among these, it is preferable to use maleic acid-modified polyolefins.

[0025] The LDPE may be any branched low-density polyethylene obtained by high-pressure radical polymerization, and is preferably a branched low-density polyethylene obtained by homopolymerizing ethylene by high-pressure radical polymerization.

[0026] LLDPE is produced by copolymerizing ethylene monomer as the main component with α-olefins such as butene-1, hexene-1, octene-1, and 4-methylpentene as comonomers by low-pressure radical polymerization using a single-site catalyst. The comonomer content in LLDPE is preferably in the range of 0.5 to 20 mol%, and more preferably in the range of 1 to 18 mol%.

[0027] Examples of the single-site catalyst include various single-site catalysts such as metallocene catalyst systems, such as combinations of metallocene compounds of transition metals of Group IV or V of the periodic table with organoaluminum compounds and / or ionic compounds. In addition, single-site catalysts have uniform active sites, and therefore, compared with multi-site catalysts, which have non-uniform active sites, the molecular weight distribution of the resulting resin is sharper, and thus low-molecular-weight components are less likely to precipitate when the catalyst is formed into a film, and a resin with excellent physical properties such as stable lamination strength and excellent blocking resistance is obtained, which is preferable.

[0028] The density of ethylene polymers is 0.880 to 0.960 g / cm 3 It is preferable that the density is within this range. If the density is within this range, the film has appropriate rigidity, is excellent in mechanical strength such as pinhole resistance, and has improved film formability and extrusion suitability. In addition, the melting point is generally preferably within the range of 60 to 130°C, more preferably 70 to 120°C. If the melting point is within this range, processing stability (dead hold property) and co-extrusion processability are improved. Furthermore, the MFR (190°C, 21.18N) of the ethylene polymer is preferably 0.1 to 20g / 10min, more preferably 0.5 to 10g / 10min. If the MFR is within this range, the film extrusion moldability is improved.

[0029] The content of the ethylene-based polymer in the intermediate layer (B) is preferably at least 50% by mass, more preferably from 60 to 100% by mass, and particularly preferably from 80 to 100% by mass. The additives and the like that can be used in the intermediate layer (B) are the same as those explained above in relation to the heat-sealing layer (A).

[0030] Of the layers constituting the heat-sealable film of this embodiment, it is preferable that the heat-sealable layer (A) is designed to obtain an appropriate seal strength, etc., and it is preferable that the laminate layer (C) is designed taking into consideration the laminate strength between the base film, etc., while it is preferable that the intermediate layer (B) is designed to obtain adhesion between the heat-sealable layer (A) and the laminate layer (C). More specifically, the thickness of the intermediate layer (B) is preferably 2 μm or more, and particularly preferably 3 μm or more. On the other hand, the thickness of the intermediate layer (B) is preferably 20 μm or less, and particularly preferably 15 μm or less.

[0031] Laminate layer (C) The laminate layer (C) constituting the heat-sealable film of the present embodiment can be laminated with other layers including a substrate film described below, if necessary or desired. Therefore, it is preferable to design the laminate layer (C) in consideration of the laminate strength between the laminate layer (C) and other layers including the base film. For example, it is preferable to use the same material as the base film and other layers, and therefore it is possible to use polyester-based materials such as PET and polyamide-based materials such as nylon, which are preferably used for base films. In addition, in order to further improve the laminate strength between the laminate layer (C) and other layers, the surface of the laminate layer (the surface opposite to the surface to be laminated with the (B) intermediate layer) may be subjected to a corona treatment, a roughening treatment, or other treatment.

[0032] On the other hand, from the viewpoint of improving the lamination strength with the (B) intermediate layer, it is also preferable to use the same type of material as that of the (B) intermediate layer, more specifically, polyolefin, more preferably an ethylene-based polymer. The additives and the like that can be used in the laminate layer (C) are the same as those explained above in relation to the heat-sealing layer (A).

[0033] When the intermediate layer (B) contains an ethylene-based polymer, it is preferred that the laminate layer (C) also contains an ethylene-based polymer from the viewpoint of lamination strength with the intermediate layer (B). More specifically, the content of the ethylene polymer in the laminate layer (C) is preferably 50% by mass or more, more preferably 60 to 99.9% by mass, and particularly preferably 80 to 99.9% by mass.

[0034] From the viewpoint of preventing blocking during storage of the heat-fusible film of this embodiment, the laminate (C) layer may contain an anti-blocking agent. As the blocking inhibitor, powdered silica, preferably synthetic silica, etc., can be suitably used. From the viewpoint of uniformly dispersing the powdered silica in the laminate layer (C), the powdered silica may be dispersed in a resin having excellent miscibility with the material constituting the laminate layer (C), for example, in low-density polyethylene, to form a master batch, and then the master batch may be added to the material constituting the laminate layer (C).

[0035] There are no particular limitations on the thickness of the laminate layer (C), but from the standpoint of laminate strength etc., it is preferably 5 μm or more, and particularly preferably 10 μm or more. The thickness of the laminate layer (C) is preferably 20 μm or less, and particularly preferably 15 μm or less.

[0036] As described above, the heat-sealable film of this embodiment has a heat-sealable layer (A), an intermediate layer (B), and a laminate layer (C). In the laminate film of this embodiment, the laminate layer (C) and the heat-sealable layer (A) are laminated preferably via the intermediate layer (B), but other layers may be present, for example, an adhesive layer may be interposed between the heat-sealable layer (A) and the intermediate layer (B).

[0037] The heat-sealable film of this embodiment can be produced by various known film forming methods, for example, a method in which the films to be the laminate layer (C), intermediate layer (B), and heat-sealing layer (A) are formed in advance, a coating layer is formed on the heat-sealing layer (A), and these films are laminated together to form a laminated film; a method in which a multilayer film consisting of the intermediate layer (B) and the heat-sealing layer (A) is obtained using a multilayer die, a laminate layer (C) is extruded on the intermediate layer (B) surface to form a laminated film, and then a coating layer is formed on the heat-sealing layer (A); a multilayer film consisting of the laminate layer (C) and the intermediate layer (B) is obtained using a multilayer die, a heat-sealing layer (A) is extruded on the intermediate layer (B) surface to form a laminated film, and then a coating layer is formed on the heat-sealing layer (A); or a method in which a laminate film consisting of the laminate layer (C), intermediate layer (B), and heat-sealing layer (A) is obtained using a multilayer die, and then a coating layer is formed on the heat-sealing layer (A).

[0038] As the film forming method, various known film forming methods, specifically, a T-die cast film forming method, an inflation film forming method, and the like, can be adopted. The laminated film of the embodiment and each of the layers constituting the laminated film may be a non-stretched film (unstretched film) or a stretched film.

[0039] The thickness of the heat-sealable film of the present embodiment is not particularly limited, but from the viewpoint of ensuring practical strength, etc., it is usually 10 μm or more, preferably 15 μm or more, and more preferably 20 μm or more. On the other hand, from the viewpoint of having practical flexibility even after being laminated with a base film, etc., it is usually 100 μm or less, preferably 80 μm or less, and more preferably 70 μm or less.

[0040] The heat-sealable film of the present embodiment may be a stretched film or a non-stretched film, but from the viewpoint of improving mechanical properties, it is preferably a stretched film, and particularly preferably a biaxially stretched film. As the biaxial stretching, a method such as sequential biaxial stretching, simultaneous biaxial stretching, or multi-stage stretching is appropriately adopted. The conditions for biaxial stretching may be the same as those for producing known biaxially stretched films. For example, in the case of the sequential biaxial stretching method, the longitudinal stretching temperature is 100°C to 145°C, the stretching ratio is in the range of 4 to 7 times, the transverse stretching temperature is 150°C to 190°C, and the stretching ratio is in the range of 8 to 11 times.

[0041] Coating Layer The heat-sealable film of the present invention has a coating layer on the surface of a polymer film containing a heat-sealable polymer, preferably on the heat-sealable layer (A) thereof. The coating layer contains (a) a low molecular weight surfactant and (b) a polymeric surfactant, and the blending ratio of the (a) low molecular weight surfactant to the (b) polymeric surfactant is 95 / 5 to 5 / 95 by mass. By having a coating layer containing the (a) low molecular weight surfactant and the (b) polymeric surfactant in the above blending ratio, the heat-sealable film of the present invention can achieve high levels of practically valuable properties, such as anti-fogging properties, heat seal strength (easy opening properties), and low blocking properties, which exceed the limits of conventional technology.

[0042] The blending ratio of (a) the low molecular weight surfactant and (b) the polymeric surfactant is more preferably 75 / 25 to 25 / 75 on a mass basis. The compounding ratio of (a) the low molecular weight surfactant and (b) the high molecular weight surfactant in the coating layer is often almost the same as the compounding ratio of the coating composition used to form the coating layer, and therefore can be appropriately adjusted by adjusting the compounding ratio of the coating composition. Even when the blending ratio of the (a) low molecular weight surfactant and the (b) polymer surfactant in the coating layer is different from that in the coating composition because the (a) low molecular weight surfactant and / or the (b) polymer surfactant are volatile or decomposable, the blending ratio of the coating layer can be appropriately adjusted by blending the coating composition, for example, by experimentally identifying the relationship between the blending ratios of the two.

[0043] There is no particular limitation on the thickness of the coating layer, but it is preferably 0.2 to 0.005 μm, and particularly preferably 0.1 to 0.005 μm. In addition, when specifying the coating layer based on the coating amount (mass), the coating amount of the coating layer is set to 0.2 g / m after drying from the viewpoint of not impairing the function of the heat-sealing layer (A). 2 It is preferable that: On the other hand, in order to fully realize the effect of the coating, the coating amount of the coating layer is set to 0.005 g / m after drying. 2 More preferably, it is equal to or greater than this. The coating weight of the coating layer after drying is 0.2 to 0.005 g / m 2 More preferably, the thickness is 0.1 to 0.005 g / m 2 It is particularly preferred that: The amount of coating layer applied can be calculated from the difference in mass between the heat-sealable film before and after the coating layer is formed, and the area of ​​the heat-sealable film.

[0044] There are no particular limitations on the method for forming the coating layer. From the viewpoint of productivity, etc., it is preferable to apply a coating agent containing (a) a low molecular weight surfactant and (b) a polymer surfactant in a predetermined ratio onto a polymer film, and then harden the coating agent by drying or the like to form a coating layer. The coating agent may contain a solvent such as water or an organic solvent, if necessary. The solvent is not particularly limited, but water, water-soluble solvents, non-water-soluble solvents, etc. can be preferably used. Here, the term "water-soluble solvent" refers to a solvent that is gently stirred with the same volume of pure water at 1 atmosphere and 20°C, and the mixture has a uniform appearance after the flow has subsided. On the other hand, the term "non-aqueous solvent" refers to a solvent that is gently stirred with the same volume of pure water at 1 atmosphere and 20°C, and the mixture cannot maintain a uniform appearance after the flow has subsided.

[0045] The water-soluble solvent is not particularly limited, but preferred examples thereof include alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, and diethylene glycol methyl ether; ketones such as acetone; and ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether.

[0046] Preferred examples of the non-water-soluble solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; hydrocarbons such as hexane, heptane, and octane; aromatics such as benzene, toluene, xylene, and cumene; and esters such as ethyl acetate and butyl acetate.

[0047] These solvents may be used alone or in combination of two or more kinds. There is no particular restriction on the amount of the solvent used, but it is preferable to use an amount such that the total amount of (a) the low molecular weight surfactant and (b) the polymer surfactant is 0.1 to 15 parts by mass, and it is particularly preferable to use an amount such that the total amount of the low molecular weight surfactant and (b) the polymer surfactant is 0.1 to 5.0 parts by mass, when the entire coating agent is taken as 100 parts by mass.

[0048] The coating agent may contain additives other than (a) the low molecular weight surfactant, (b) the polymer surfactant, and the solvent, as necessary. The additives are not particularly limited, but examples thereof include anti-fogging aids, slip agents (such as silicone emulsions mainly composed of polydimethylsiloxane), antistatic agents, antioxidants, antibacterial agents, ultraviolet absorbers, etc. These additives may be used alone or in combination of two or more.

[0049] The method for applying the coating agent is not particularly limited, but preferred examples include a spray coater, a roll coater, a gravure roll coater, a knife coater, an air knife coater, a rotor dampening, and an applicator system.

[0050] The drying temperature is not particularly limited, but it is preferable to dry at a temperature not exceeding the glass transition temperature (Tg) of the polymer film. The drying time is not particularly limited, but is preferably 0.01 to 10 minutes, and more preferably 0.05 to 3 minutes.

[0051] (a) Low molecular weight surfactants There are no particular limitations on the (a) low molecular weight surfactant used in the coating layer of the present invention, and any low molecular weight compound that exhibits surface activity can be used as the (a) low molecular weight surfactant. Here, "low molecular weight" means a molecular weight of not more than 5000. (a) The molecular weight of the low molecular weight surfactant is preferably not more than 3000, and particularly preferably not more than 1500. The (a) low molecular weight surfactant may be any of an anionic low molecular weight surfactant, a cationic low molecular weight surfactant, and a nonionic low molecular weight surfactant. From the viewpoint of the stability and anti-fogging properties of the coating agent, nonionic low molecular weight surfactants are preferred, and fatty acid ester low molecular weight surfactants are particularly preferred.

[0052] Preferred examples of the anionic low molecular weight surfactant include alkyl sulfates such as sodium lauryl sulfate, triethanolamine lauryl sulfate, and potassium lauryl sulfate; alkylaryl sulfonic acids such as lignin sulfonates, alkylbenzene sulfonates, and alkylnaphthalene sulfonates, and salts thereof; polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylaryl ether sulfates, sulfosuccinates such as disodium lauryl sulfosuccinate, disodium polyoxyethylene alkyl lauryl sulfosuccinate, and dioctyl sodium sulfosuccinate; lauryl phosphoric acid, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl aryl ether phosphates, and polyoxyethylene styrenated phenol ether sulfates.

[0053] Preferred examples of the cationic low molecular weight surfactant include alkyl trimethyl ammonium halide salts such as lauryl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, lauryl trimethyl ammonium bromide, and stearyl trimethyl ammonium bromide; alkyl dimethyl benzyl ammonium halide salts such as lauryl dimethyl benzyl ammonium chloride, stearyl dimethyl benzyl ammonium chloride, and tri(polyoxyethylene)stearyl ammonium chloride; stearyl pentaethoxy ammonium chloride; and chloro-[2-hydroxy-3-(trimethylammonio)propyl]hydroxyethyl cellulose.

[0054] Preferred examples of the nonionic low molecular weight surfactant include alkylolamides such as lauric acid diethanolamide, lauric myristic acid diethanolamide, myristic acid diethanolamide, and polyoxyethylene stearic acid amide; polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene dinonylphenyl ether; polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether; polyethylene glycol fatty acid esters such as polyethylene glycol monooleate, polyethylene glycol dioleate, polyethylene glycol monostearate, and polyethylene glycol distearate; decaglycerin monocaprylate, glycerin monostearate, sorbitan monocaprylate, sorbitan monolaurate, sorbitan monopalmitate, Examples of the sorbitan fatty acid esters include sorbitan monostearate, sorbitan distearate, sorbitan trioleate, sorbitan sesquioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan trioleate; sorbit fatty acid esters such as polyoxyethylene sorbit monooleate and polyoxyethylene sorbit tetraoleate; polyoxyethylene polyoxypropylene alkyl ethers such as polyoxyethylene polyoxypropylene alkyl ethers (blocked), polyoxyethylene polyoxypropylene glycol, and ethylenediaminetetrapolyoxyethylene polyoxypropylene; polyoxyethylene alkylaryl ethers; polyoxyethylene styrenated phenol ethers; polyoxyethylene alkyl esters; and polyoxyethylene styrenated phenol ether polymers. Among them, fatty acid esters are preferred, and polyhydric alcohol fatty acid esters are particularly preferred. More specifically, glycerin monostearate, glycerin monolaurate, diglycerin monostearate, diglycerin monolaurate, decaglycerin oleate, decaglycerin laurate, etc. can be particularly preferably used.

[0055] (b) Polymer surfactant The polymer surfactant (b) used in the present invention is not particularly limited, and any polymer compound that exhibits surface activity can be used as the polymer surfactant (b). Here, "polymer" means a molecular weight of at least 5000. The molecular weight of the (b) polymer surfactant is preferably 10,000 to 1,000,000, and particularly preferably 10,000 to 500,000.

[0056] The (b) polymer surfactant is preferably water-soluble. There are no particular limitations on the structure of the (b) polymer surfactant, but it is desirable for the polymer surfactant to have a structure that has a water-insoluble polymer main chain and has water-soluble groups in its side chains, thereby making the polymer compound as a whole water-soluble. The (b) polymer surfactant may be any of anionic polymer surfactants, cationic polymer surfactants, and nonionic polymer surfactants. Which of these it is usually depends on the type, number, proportion, etc. of the side chain groups. The (b) polymer surfactant may be any of a natural polymer surfactant, a semi-synthetic polymer surfactant, and a synthetic polymer surfactant. From the viewpoints of control of the structure and physical properties and ease of availability, however, a synthetic polymer surfactant is preferable.

[0057] Preferred examples of the anionic polymer surfactant include (co)polymers of (meth)acrylic acid, maleic acid, and the like, carboxymethylcellulose, carboxystarch, (meth)acrylic acid grafted starch, sodium alginate, sodium pectinate, xanthan gum, and the like. Among them, acrylic polymer surfactants, that is, (co)polymers of (meth)acrylic monomers are preferably used.

[0058] Examples of the (meth)acrylic monomer used in the (co)polymer of (meth)acrylic monomer include a (meth)acrylic monomer having a hydroxy group, a (meth)acrylic monomer having a carboxy group, a (meth)acrylic acid ester monomer, a (meth)acrylic monomer having a silyl group, and a (meth)acrylic monomer having an isocyanate group.

[0059] The (meth)acrylic monomer having a hydroxy group is not particularly limited, but includes 2-hydroxyethyl (meth)acrylate (HEMA), 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, etc. Among these, it is preferable to use 2-hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate.

[0060] The (meth)acrylic monomer having a carboxy group is not particularly limited, and examples thereof include unsaturated monocarboxylic acids such as (meth)acrylic acid, ((meth)acryloyloxy)acetic acid, 2-carboxyethyl (meth)acrylate, 3-carboxypropyl (meth)acrylate, 1-[2-((meth)acryloyloxy)ethyl] succinate, 1-(2-(meth)acryloyloxyethyl) phthalate, 2-((meth)acryloyloxy)ethyl hydrogen hexahydrophthalate, and lactone-modified products thereof; and carboxy group-containing polyfunctional (meth)acrylates obtained by reacting unsaturated dicarboxylic acids (maleic acid, etc.), acid anhydrides (succinic anhydride, maleic anhydride, etc.) with hydroxyl group-containing polyfunctional (meth)acrylates (pentaerythritol triacrylate). Among these, from the viewpoint of ease of adjusting the acid value, it is preferable to use methacrylic acid, (acryloyloxy)acetic acid, 2-carboxyethyl acrylate, and 3-carboxypropyl acrylate, and it is more preferable to use methacrylic acid.

[0061] The (meth)acrylic acid ester monomer is not particularly limited, but may be methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-pentafluoropropyl (meth)acrylate, perfluorocyclohexyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, β-(perfluorooctyl)ethyl (meth)acrylate, glycidyl (meth)acrylate, allyl glycidyl ether, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, glycerol mono(meth)acrylate, aminoethyl (meth)acrylate, N-monoalkylaminoalkyl (meth)acrylate, N,N-dialkylaminoalkyl (meth)acrylate, 2-aziridinylethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, allyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate Examples of the acrylate include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and allyl (meth)acrylate.

[0062] Examples of the (meth)acrylic monomer having a silyl group include, but are not limited to, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, and γ-(meth)acryloxypropyltriisopropoxysilane.

[0063] The (meth)acrylic monomer having an isocyanate group is not particularly limited, but examples thereof include (meth)acryloyl isocyanate, and (meth)acryloyl isocyanate ethyl phenol or methyl ethyl ketoxime adducts.

[0064] Furthermore, the other monomer is not particularly limited, but examples thereof include vinyl esters, vinyl ethers, nitrile group-containing ethylenically unsaturated monomers, vinyl compounds having an aromatic ring, methylolamide group-containing or alkoxylated polymerizable monomers, silyl group-containing polymerizable monomers, oxazoline group-containing polymerizable monomers, amide group-containing polymerizable monomers, carbonyl group-containing polymerizable monomers, and other compounds. When other monomers are used, the proportion of the structural units derived from the other monomers in the acrylic polymer surfactant is preferably 10 to 90 mol %, and particularly preferably 30 to 70 mol %.

[0065] Commercially available acrylic polymer surfactants applicable to the present invention include, for example, Dexnol RS-811 (manufactured by Nippon Nyukazai Co., Ltd.), BYK-3441 (manufactured by BYK Japan KK), BYK-350 (manufactured by BYK Japan KK), BYK-381 (manufactured by BYK Japan KK), and Elecut C048 (manufactured by Takemoto Oil Co., Ltd.).

[0066] Other preferred examples of the anionic polymer surfactant include polyvinylpyridine, polyvinylpyrrolidone, polyethyleneimine, cationic starch, and chitosan.

[0067] Preferred examples of nonionic polymeric surfactants include polyoxyethylene-polyoxypropylene, polyvinyl alcohol, polyvinyl ether, polyacrylamide, ethylene oxide adducts of alkylphenol formaldehyde condensates, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, corn starch, and various starches.

[0068] Further, more specific examples of suitable polymer surfactants include the following. (1) Poly(4-vinylpyridine) type cationic surfactants (2) Graft copolymers of cationic derivatives of linear polysaccharides and olefin monomers (3) Copolymers of cationic monomers and nonionic monomers (e.g., copolymers of alkylvinylpyridinium and alkylene oxide adducts of alkylvinyl alcohol). (4) Poly 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride (5) Polydimethylaminoethyl methacrylate (6) Salts of acrylic acid polymers with alkali metals, amines, and ammonia (7) Copolymers of maleic anhydride and acrylic acid and their salts with alkali metals, amines and ammonia (8) Copolymers of itaconic acid and acrylic acid and their salts with alkali metals, amines, and ammonia (9) Alkali metal salts of sulfonated styrene-maleic anhydride copolymers (10) Alkali metal salts of polyvinyl sulfonic acid (11) Alkali metal salts of polystyrene sulfonic acid (12) Polymethacryloyloxypropylsulfonic acid (13) Alkali metal salts of polyepoxysuccinic acid (14) Formalin condensation product of sodium naphthalenesulfonate (15) Melamine sulfonic acid-formaldehyde condensate (16) Copolymer of alkylaminoalkyl(meth)acrylamide and alkylacrylamide (meth)acrylate or acrylonitrile (17) Fatty acid dextrin (18) Carboxymethylcellulose (19) Polyvinyl alcohol (20) Polyoxyethylene (hereinafter abbreviated as POE)-polyoxypropylene (hereinafter abbreviated as POP) block polymer (21) Ethylenediamine-POE·POP block polymer (22) POE-POP triblock polymer

[0069] Base Film If desired, the heat-sealable film of the present embodiment can be laminated with a substrate film, preferably at its laminating layer (C).

[0070] There is no particular limitation on the base film, and for example, films that are normally used for plastic packaging can be suitably used. Preferred materials for the substrate film include, for example, plastic films made of thermoplastic resins such as polyolefins, such as crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly4-methylpentene-1, low-, medium-, or high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ionically crosslinked olefin copolymers (ionomers); aromatic vinyl copolymers, such as polystyrene and styrene-butadiene copolymer; halogenated vinyl polymers, such as polyvinyl chloride and vinylidene chloride resin; nitrile polymers, such as acrylonitrile-styrene copolymer and acrylonitrile-styrene-butadiene copolymer; polyamides, such as nylon 6, nylon 66, and para- or meta-xylylene adipamide; polyesters, such as polyethylene terephthalate (PET) and polytetramethylene terephthalate; various polycarbonates; and polyacetals, such as polyoxymethylene. In addition, when the contents to be packaged are sensitive to oxygen, the above film may be provided with a film vapor-deposited with a metal oxide or the like, a film coated with an organic compound, or a layer made of ethylene vinyl alcohol copolymer (EVOH) resin. Plastic films made of these materials may be used in an unstretched, uniaxially stretched, or biaxially stretched state.

[0071] As the base film, these plastic films can be used as a single layer or as a laminate of two or more types. It is also possible to construct the base film by laminating one or two or more types of these plastic films with a metal foil such as aluminum, paper, cellophane, etc. Examples of preferred substrate films include single-layer films made of stretched nylon film and stretched polyester film, two-layer films made of a polyolefin film such as low-density polyethylene or polypropylene laminated with PET, and three-layer films made of PET / nylon / polyethylene laminated. When producing these laminated films, an adhesive or anchor agent can be interposed between the layers as necessary. An ink layer expressing a design can also be provided.

[0072] There is no particular restriction on the method of laminating the base material layer to the laminate layer (C), etc., but for example, the base material film can be directly laminated to the laminate layer (C) by extrusion lamination, etc. Also, the base material film may be laminated to the laminate layer (C) via an adhesive by dry lamination, etc. As the adhesive, a usual adhesive such as a urethane adhesive, an acid-modified polyolefin adhesive, a polyester adhesive, a polyether adhesive, or a polyamide adhesive can be used. The thickness of the substrate film can be set arbitrarily, but can usually be selected within the range of 12 to 500 μm, preferably 12 to 50 μm.

[0073] The heat-sealable film of the present invention and a laminate film in which a base film is laminated to the laminate layer (C) of the heat-sealable film of this embodiment are preferably used in various applications, and are particularly suitable for use as packaging materials.

[0074] A preferred example of such a packaging material is a lid material, which can be used as a lid material for a container in which the heat-sealable film of the present invention and the laminate film in which a base film is laminated on the laminate layer (C) of the heat-sealable film of the present embodiment are used as a lid material for a container in which the heat-sealable layer (A) is used as the innermost layer on the container side. When used as a container lid material, the heat-sealable film of the present invention may be used as a lid material as it is, or may be printed before use. It may be laminated with a printed or unprinted base film to form a lid material. Depending on the application, it may be cut in advance to fit the shape of the container to form a lid material. When used as a container lid material, it is preferable to laminate it with a base film.

[0075] The laminated film of the present invention can form a heat seal layer by heat sealing the heat seal layer (A) to various adherends. Examples of such adherends include propylene polymers, polystyrene, polyester, polycarbonate, polyvinyl chloride, etc. These adherends can be in various shapes such as films, sheets, trays, cups, bottles, etc. Among these, polyester is particularly preferable as the adherend because the heat seal layer is excellent in sealing property, easy opening property, heat resistance, oil resistance, etc.

[0076] There is no particular restriction on the items to be stored in the packaging container, but it can be preferably used for packaging food, medicines, medical equipment, daily necessities, miscellaneous goods, etc. Taking advantage of the excellent visibility, anti-fogging properties, heat seal strength (easy opening property), and low blocking property of the heat-sealable film of the present invention, it is particularly suitable for use as a packaging container for prepared foods, salads, fruits, etc. EXAMPLES

[0077] The present invention will be specifically described below with reference to examples and comparative examples. Note that the present invention is not limited in any sense by the following examples.

[0078] The physical properties and characteristics in the examples and comparative examples were evaluated by the following methods. (1) Anti-fogging properties 30 mL of purified water was placed in a transparent beaker, covered with the sample film with the measurement surface (coated surface) facing inward (water side), and stored in a refrigerator (set at about 5°C). After 24 hours of storage, the film was removed from the refrigerator and the degree of cloudiness of the film immediately after removal was visually observed and rated out of 5 points, with 5 points for no cloudiness and 1 point for cloudiness and opacity. Figure 1(a) shows a schematic diagram of the evaluation criteria, and (b) shows a photograph of an actual anti-fogging evaluation example.

[0079] (2) Blocking properties Two sample films were stacked with the coated side and the uncoated side in contact, and stored at 40°C under a pressure of 4 kg for 24 hours. The peel strength (N / 5.2 cm) of the two sample films was then measured using a universal tensile tester (manufactured by A&D Co., Ltd.). 2 ) was measured. The measurement results were evaluated according to the following criteria. ◎: 5N / 5.2cm 2 less than 〇:5N / 5.2cm 2 Above, 10N / 5.2cm 2 less than ×:10N / 5.2cm 2 End

[0080] (3) Heat sealability The coated side of the sample film was placed on an A-PET sheet (softening point 77°C, crystallization temperature 126°C), and heat-sealed for 1.0 second with a 5mm-wide seal bar at 120-180°C and 0.2MPa pressure using a precision heat sealer (manufactured by Tester Sangyo). After cooling, a 15mm-wide test piece was cut from the heat-sealed sample, and the maximum load was measured by peeling it off in a 180° direction using a universal tensile tester (manufactured by A&D Co., Ltd.) at a tensile speed of 300mm / min in a thermostatic room at 23°C and 50%RH (unit: N / 15mm). The obtained seal strength value was compared with the seal strength of a blank (a film with the same composition as the sample film except for the absence of a coating) and evaluated according to the following criteria. ◎: Heat seal strength equal to or greater than that of the blank (but less than twice the strength of the blank) ◯: Heat seal strength was lower than that of the blank, but heat sealing was possible. ×: Heat sealing was not possible (heat seal strength: 0).

[0081] Details of the materials / components used in the examples / comparative examples are as follows: Base Film A three-layer laminate film having a thickness of 30 μm, consisting of a heat-sealing layer, an intermediate layer and a laminate layer, each having a thickness of 5.1 μm, 6.3 μm and 18.6 μm, was used as the substrate film. The resins constituting each layer were as follows: Heat-sealed layer Polyethylene terephthalate resin (Tg: 73°C, density: 1340kg / m 3 ) Middle class Polyolefin resin (MFR (2.16 kg 190°C): 5.6 g / 10 min, density: 903 kg / m 3 ) Laminate layer Polyethylene resin (MFR (2.16 kg 190°C): 3 g / 10 min, density: 928 kg / m 3 , melting point: 114℃)

[0082] Polymer Surfactants An acrylic polymer surfactant 1 (aqueous solution with 15% solid content, an acrylic polymer containing a quaternary ammonium salt, molecular weight approximately 26,000, acid value 1.0, melting point: 118° C.) was used.

[0083] Low molecular weight surfactants Low molecular weight surfactants 1 (Glycerol monostearate, molecular weight: 369) was used. Low molecular weight surfactants 2 (Glycerol monolaurate, molecular weight: 276) was used. Low molecular weight surfactants 3 (Diglycerol monolaurate, molecular weight: 349) was used. Low molecular weight surfactants 4 (Decaglycerol laurate, molecular weight 933) was used.

[0084] Comparative Example 1 For comparison, the above substrate film that was not coated was evaluated for anti-fogging properties, blocking strength, and heat seal strength according to the above methods. The results are shown in Table 1. Since no coating was applied, anti-fogging properties could not be achieved.

[0085] Comparative Example 2 No polymer surfactant was used, and low molecular weight surfactant 3 was used as a low molecular weight surfactant. The low molecular weight surfactant was dispersed in a solvent (a mixed solvent of isopropanol and water) to produce a coating agent with a concentration of 2 mass %. The coating agent was applied to the heat-sealing layer side of the substrate film using a bar coater, and then dried for 1 minute in a thermostatic chamber adjusted to 80°C to obtain a film in which a coating layer was formed on the laminate layer of the substrate film. The coating amount was calculated from the mass after drying and was 0.2 g / m 2 It was. The obtained film was evaluated for antifogging property, blocking strength, and heat seal strength according to the above-mentioned methods. The results are shown in Table 1. The anti-fogging property was excellent and the heat seal strength was adequate, but severe blocking occurred.

[0086] Example 1 A film having a coating layer formed thereon was produced and evaluated in the same manner as in Comparative Example 2, except that 25 parts by mass of polymer surfactant 1 and 75 parts by mass of low molecular surfactant 3 were added and dispersed in a solvent (a mixed solvent of isopropanol and water) to produce a coating agent with a concentration of 2% by mass. The results are shown in Table 1. The anti-fogging property, heat sealability and blocking resistance were all good.

[0087] (Example 2, Comparative Example 3) A film having a coating layer formed thereon was produced and evaluated in the same manner as in Example 1, except that the mixing ratio of the polymer surfactant 1 and the low molecular weight surfactant 3 was changed as shown in Table 1. The results are shown in Table 1. Example 2 was excellent in all of the antifogging properties, heat sealability, and blocking resistance, but Comparative Example 3 was insufficient in heat seal strength.

[0088] (Examples 3 to 10) A film having a coating layer formed thereon was produced and evaluated in the same manner as in Example 1, except that the mixing ratio of molecular surfactant 1 and low molecular surfactant 3 and the coating amount were changed as shown in Table 1. The results are shown in Table 1. All of the examples were excellent in antifogging properties, heat sealability, and blocking resistance. [Table 1]

[0089] (Examples 11 to 13) Films having coating layers formed thereon were produced and evaluated in the same manner as in Example 4, except that the type of low molecular weight surfactant was changed to that shown in Table 2. The results are shown in Table 2 together with the results of Example 4. All of the examples were excellent in antifogging properties, heat sealability, and blocking resistance. [Table 2] [Industrial Applicability]

[0090] The heat-sealable film of the present invention combines highly practical properties, such as anti-fogging properties, heat seal strength (easy opening), and low blocking properties, at a level that exceeds the limits of conventional technology, and can be suitably used in a variety of applications, including as a lid material for easy-open plastic containers for storing various products, such as food, that require visibility of the contents, and has high applicability in various industrial fields, such as food processing, distribution, retail, and restaurant services.

Claims

1. a coating layer is provided on the surface of a polymer film containing a heat-fusible polymer, the coating layer containing (a) a low molecular weight surfactant and (b) a high molecular weight surfactant, the blending ratio of the low molecular weight surfactant and the high molecular weight surfactant being 95 / 5 to 5 / 95 by mass; (a) the low molecular weight surfactant comprises a nonionic surfactant; (b) the polymer surfactant includes an acrylic surfactant; The coating amount of the coating layer is 0.1 g / m 2 or less. Heat-sealable film.

2. The heat-sealable film according to claim 1 , wherein the heat-sealable polymer is polyethylene terephthalate.

3. 3. An easy-open film comprising a heat-sealable layer (A) made of the heat-sealable film according to claim 1, an intermediate layer (B), and a laminate layer (C) laminated in this order.

4. The easy-open film according to claim 3 , wherein the intermediate layer (B) and / or the laminate layer (C) contains an ethylene-based polymer.

5. The easy-open film according to claim 3 , wherein the intermediate layer (B) contains an acid-modified polyolefin.

6. An easy-open package comprising a lid material having the easy-open film according to any one of claims 3 to 5, and a container.

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