Laminated film for pouch and pouch

Abstract

To provide a laminated film for a pouch, and a pouch, capable of achieving gas barrier properties and drop strength using a simple structure.SOLUTION: A laminated film for a pouch 20 comprises, in order from the inner layer side, a heat seal layer 30, an adhesive layer 31, a base material layer 40, a vapor deposition layer 41, a first coating layer 42, a print layer 50, and a second coating layer 51, wherein the heat seal layer 30, the adhesive layer 31, and the base material layer 40 are laminated with no other layer interposed among them, and the second coating layer 51 is composed of an epoxy resin, a polyester resin, or an acrylic resin.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a laminated film for a pouch and to a pouch. [Background technology]

[0002] Conventionally, laminated films for pouches formed into a bag shape by thermally bonding overlapping laminated films have been known that are made by laminating multiple layers such as a base layer and a heat seal layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-249176 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the course of research and development into such laminated films, the applicant has found that there is room for improvement in conventional laminated films in terms of achieving both gas barrier properties and drop strength.

[0005] Therefore, the present invention is intended to solve these problems, and has an object to provide a laminated film for a pouch and a pouch that can achieve both gas barrier properties and drop strength with a simple configuration. [Means for solving the problem]

[0006] The laminated film of the present invention has, in order from the inner layer side, a heat seal layer, an adhesive layer, a base layer, a vapor deposition layer, a first coating layer, a printing layer, and a second coating layer, the heat seal layer, the adhesive layer, and the base layer are laminated without any other layers interposed between them, and the second coating layer is formed from an epoxy-based resin, a polyester-based resin, or an acrylic-based resin, thereby solving the above-mentioned problems. In the laminate film, the first coating layer may contain at least one of a water-soluble polymer, a metal alkoxide, or a hydrolysate thereof. Any of the above laminated films has an oxygen permeability of 1.0cc / (m after retorting at 127℃ for 30 minutes. 2 ·day) or less. In any of the laminated films described above, the heat seal layer may be formed from unstretched polypropylene. The pouch of the present invention solves the above problems by being formed into a bag shape from the laminated film. Effect of the Invention

[0007] According to the present invention, it is possible to achieve both gas barrier properties and drop strength. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view showing a pouch according to an embodiment of the present invention. [Diagram 2] Cross-section of the pouch. [Diagram 3] FIG. 4 is an explanatory diagram showing the results of a test carried out to confirm the performance of the laminated film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A pouch 10 according to one embodiment of the present invention will now be described with reference to the drawings.

[0010] As shown in Figures 1 and 2, the pouch 10 is formed into a bag shape by forming an outer edge seal portion (heat seal portion) for bag making by heat-bonding the outer edges of overlapping laminated films 20, and the contents such as food are contained in the storage portion on the inner layer side.

[0011] As shown in FIG. 1, pouch 10 of this embodiment is configured as a microwave pouch provided with automatic steam release mechanism 60 that automatically releases steam within pouch 10 to the outside when heated in a microwave oven.

[0012] As shown in FIG. 1, this automatic steam release mechanism 60 has a steam release seal portion 61 formed by heat-sealing the front and back laminate films 20 (the heat seal layers 30 thereof), a steam release portion 62 (wherein the heat seal layers 30 of the front and back laminate films 20 are not heat-sealed) surrounded by the steam release seal portion 61, and a hole-like or slit-like steam release portion 63 formed in at least one of the front and back laminate films 20 in the steam release portion 62. When heated in a microwave oven, the steam release seal portion 61 peels off as the internal pressure in the storage portion of the pouch 10 increases, and the pressure within the pouch 10 is released to the outside through the steam release portion 62 and the steam release portion 63. Also, the steam release portion 62 may be open to the side edge of the pouch, and may be structured so that when the steam release seal portion 61 is peeled off, it is connected to the outside to release pressure. Note that automatic steam release mechanism 60 may have any structure other than that described above, as long as it allows steam generated during microwave heating to escape.

[0013] Next, a specific embodiment of the laminate film 20 constituting the pouch 10 will be described.

[0014] First, as shown in Figures 2 and 3, each laminate film 20 has, from the inner layer side, a heat seal layer 30, an adhesive layer 31, a base layer 40, a vapor deposition layer 41, a first coating layer 42, a printing layer 50, and a second coating layer 51.

[0015] As shown in FIG. 2, when the pouch 10 is made, the heat seal layer 30 is positioned on the innermost side so as to face the other laminate film 20, and is heat-sealed to the heat seal layer 30 of the other laminate film 20.

[0016] The specific embodiment of the heat seal layer 30 may be any suitable film for heat welding, such as a PP (polypropylene) film or a PE (polyethylene) film, but in this embodiment, the heat seal layer 30 is made of non-oriented polypropylene (also called CPP or cast PP film). This non-oriented polypropylene has excellent heat resistance and is used to make pouches for storing various foods, etc. In recent years, more heat resistance and drop strength (impact resistance) are required, so it is possible to use impact polypropylene as the sealant layer. This impact polypropylene (impact PP) is also called block polypropylene, impact copolymer, or high impact polypropylene, and is a material in which rubber components such as ethylene-propylene copolymer (EPR) or styrene-butadiene copolymer (SBR) are dispersed in a matrix of homopolypropylene or random polypropylene. The dispersion of such rubber components significantly improves the drop strength. In order to further improve the drop strength, high-density polyethylene, low-density polyethylene, or linear low-density polyethylene can be blended into the above materials of the sealant layer. Linear low-density polyethylene is a linear low-density polyethylene with a density in the range of 0.860 to 0.925 g / cm3, and is, for example, a copolymer of α-olefins such as butene-1, hexene-1, 4-methylpentene-1, and octene-1 with ethylene, and is reduced in density by introducing short-chain α-olefin chains as branches into long-chain ethylene chains. The thickness of the heat seal layer 30 is preferably 40 μm or more, more preferably 60 μm or more. The thickness of the heat seal layer 30 is preferably 100 μm or less, more preferably 80 μm or less.

[0017] The adhesive layer 31 is made of an adhesive such as a urethane-based adhesive or an epoxy-based adhesive, and bonds the heat seal layer 30 and the base material layer 40 together. Specifically, the heat seal layer 30 and the base material layer 40 are bonded together by a dry lamination method (a method in which an adhesive such as a urethane-based adhesive is applied to the inner layer side of the base material layer 40, the solvent is evaporated in a drying device, and the heat seal layer 30 and the base material layer 40 are then thermocompressed together). The thickness of the adhesive layer 31 is preferably 0.5 μm or more, and more preferably 1.0 μm or more. The thickness of the adhesive layer 31 is preferably 6.0 μm or less, and more preferably 4.0 μm or less.

[0018] In this embodiment, the base layer 40 is made of a polyester resin or a polyolefin resin, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polypropylene (PP), or polyethylene (PE). The base layer 40 may be formed as a mixed PET layer containing 5 to 55% by mass of modified polybutylene terephthalate (modified PBT) or 5 to 30% by mass of thermoplastic elastomer. It may also contain recycled materials or polyester or polyolefin derived from biomass. The thickness of the base layer 40 is preferably 10 μm or more, and more preferably 12 μm or more. The thickness of the base layer 40 is preferably 25 μm or less, and more preferably 16 μm or less.

[0019] The deposition layer 41 is a layer for imparting gas barrier properties to the laminated film 20, and in this embodiment, is made of aluminum oxide (alumina, Al 2 O 3 The base layer 40 is formed as a vapor-deposited layer by vapor-depositing an inorganic substance such as tantalum (ZnO), silicon (Si), aluminum (Al), or an inorganic oxide onto the outer surface of the base layer 40. The thickness of the deposited layer 41 is preferably 5 nm or more, and more preferably 10 nm or more. The thickness of the deposited layer 41 is preferably 300 nm or less, and more preferably 150 nm or less.

[0020] The first coating layer 42 is formed from a compound containing at least one of a water-soluble polymer, a metal alkoxide, and a hydrolyzate thereof (specifically, containing at least one of these as a main component). Specific examples of water-soluble polymers include polyvinyl alcohol resin (PVA), polyacrylic acid resin (PAA), ethylene-vinyl alcohol copolymer resin (EVOH), polyvinylpyrrolidone resin (PVP), starch, methylcellulose, carboxymethylcellulose, sodium alginate, etc. A specific example of a metal alkoxide is tetraethoxysilane {Si(OC 2 H 5 ) 4}, triisopropoxyaluminum {Al(O-2'-C 3 H 7 ) 3} etc. The thickness of the first coating layer 42 is preferably 0.01 μm or more, and more preferably 0.1 μm or more. The thickness of the first coating layer 42 is preferably 20 μm or less, and more preferably 10 μm or less.

[0021] The printed layer 50 is a layer that is arranged on the outer surface side of the first coated layer 42 and is made of one or more inks 50a (one color). In the example shown in Figure 2, one of the laminate films 20 (the laminate film 20 shown in the upper part of Figure 2) has a printed layer 50 formed by two inks (two colors) 50a laminated in the thickness direction of the film, and the other of the laminate films 20 (the laminate film 20 shown in the lower part of Figure 2) has a printed layer 50 formed by one ink 50a (one color) laminated in the thickness direction of the film. As shown in the example of Figure 2, there may be an area between the first coating layer 42 and the second coating layer 51 where the printing layer 50 (ink 50a) is not provided, i.e., an area where the first coating layer 42 and the second coating layer 51 are directly laminated. The thickness of each ink 50a is preferably 1.0 μm or more, and more preferably 2.0 μm or more. The thickness of each ink 50a is preferably 10.0 μm or less, and more preferably 8.0 μm or less.

[0022] The second coating layer 51 is a coating layer formed to cover the outer surface side of the printed layer 50 (and the first coating layer 42), and has the function of protecting the printed layer 50, as well as the function of protecting the first coating layer 42 and the vapor deposition layer 41 (as will be described in more detail later). The second coating layer 51 can be formed by using an epoxy resin, a polyester resin, or an acrylic resin as a main material (i.e., a component that accounts for 51% by mass or more of the second coating layer 51) and adding a curing agent such as an isocyanate composition or an amino resin to these. More preferably, an epoxy isocyanate composition obtained by curing an epoxy resin with an isocyanate composition, or an epoxy amino composition obtained by curing an epoxy resin with an amino resin can be used. The thickness of the second coat layer 51 (the thickness of the second coat layer 51 in a portion where the printed layer 50 is not interposed between the first coat layer 42 and the second coat layer 51) is preferably 0.01 μm or more, and more preferably 0.1 μm or more. The thickness of the second coat layer 51 (the thickness of the second coat layer 51 in a portion where the printed layer 50 is not interposed between the first coat layer 42 and the second coat layer 51) is preferably 20 μm or less, and more preferably 10 μm or less.

[0023] Here, the heat seal layer 30, the adhesive layer 31, and the base material layer 40 are laminated together without any other layers being interposed between them. In addition, in this embodiment, each layer 30, 31, 40, 41, 42, 50, 51 is laminated without any other layers being interposed between the layers, but other layers may be interposed between each layer 40, 41, 42, 50, 51, and other layers may be formed on the outside of the second coating layer 51.

[0024] In addition, the pouch 10 (laminated film 20) had an oxygen permeability of 1.0cc / (m after retorting at 127°C for 30 minutes. 2 ·day) or less. As mentioned above, the oxygen permeability after retorting at 127℃ for 30 minutes was 1.0cc / (m 2 In order to achieve a gas barrier life of not more than 10 days, the compounding ratios of the material components and the layer thicknesses of the deposition layer 41, which mainly performs the gas barrier function, the first coating layer 42 for protecting the deposition layer 41, and the second coating layer 51 for protecting these layers 41 and 42, may be adjusted.

[0025] Next, the tests carried out to confirm the gas barrier properties and drop strength (impact resistance) will be described below with reference to FIG.

[0026] First, in this test, multiple laminate films (Examples, Comparative Examples 1 to 3) with different layer structures were prepared, and the oxygen transmission rate (OTR, cc / m 2 ·day·atm), and pouches (test samples) made of each laminated film (Examples, Comparative Examples 1 to 3) were prepared. Each pouch (test sample) containing 180 ml of water was dropped 10 times from a height of 120 cm onto the floor to check the drop breakage rate (%) of each pouch (test sample).

[0027] The specific test conditions are as follows:

[0028] "Layer structure of laminated film" Example: A laminated film in which, from the inner layer side, a CPP layer (heat seal layer), an adhesive layer, a PET layer (base layer), a deposition layer, a first coating layer, a printing layer, and a second coating layer are laminated. Comparative Example 1: A laminated film in which, from the inner layer side, a CPP layer (heat seal layer), an adhesive layer, a second coating layer, a printing layer, a first coating layer, a deposition layer, and a PET layer (base layer) are laminated. Comparative Example 2: A laminated film in which, from the inner layer side, a CPP layer (heat seal layer), an adhesive layer, a printing layer, a first coating layer, a vapor deposition layer, and a PET layer (base layer) are laminated. Comparative Example 3: A laminated film in which, from the inner layer side, a CPP layer (heat seal layer), an adhesive layer, a PET layer (base layer), a deposition layer, and a first coating layer are laminated. Here, specific aspects of each of the above layers are as follows. CPP layer (heat seal layer): A 70 μm layer made of non-oriented polypropylene (CPP) Adhesive layer: 3 μm layer of urethane adhesive PET layer (base layer): 12 μm layer made of PET Deposited layer: 15 nm layer of aluminum oxide First coating layer: Polyvinyl alcohol resin (PVA) and tetraethoxysilane {Si(OC 2 H 5 ) 4} 0.3 μm layer Printing layer: A layer of two types (two colors) of ink laminated together Second coating layer: 2 μm layer made of epoxy isocyanate-based composition Furthermore, the thickness (μm) of each layer above indicates the thickness of the portion where there is no ink when that layer is adjacent to a printed layer. "Pouch (test sample) appearance" For each laminated film (Examples and Comparative Examples 1 to 3), a pouch with a capacity of 180 ml was formed in the same manner as the pouch shown in Figure 1 (a flat pouch made of two laminated films formed with an automatic steam venting mechanism 60, etc.) and used as a test sample. "Oxygen permeability measurement" Pouches (test samples) containing 180 ml of water were retorted at 127°C for 30 minutes, and then samples were cut out from each pouch (test sample) and the oxygen transmission rate (OTR, cc / m 2 The oxygen permeability (°C / day / atm) was measured using an oxygen transmission rate measuring device (OX-TRAN manufactured by MOCON) at 23°C and a relative humidity of 60%. Two samples were used for the measurement. "Measurement of bag breakage rate (%)" A pouch (test sample) containing 180 ml of water was dropped ten times onto the floor from a height of 120 cm to check for breakage (water leakage). The number of pouches (test samples) used in the measurement was 30 for each laminate film (Example and Comparative Examples 1 to 3).

[0029] The experimental results shown in Figure 3 reveal the following:

[0030] First, from a comparison between the Examples and Comparative Examples (particularly Comparative Example 3), it was found that gas barrier properties could be ensured when a second coating layer was provided on the outer layer side of the vapor deposition layer (aluminum oxide layer) and the first coating layer. This is believed to be because in Comparative Example 3, the gas barrier properties of the vapor-deposited layer (aluminum oxide layer) are impaired due to deterioration of the first coating layer caused by water (especially steam), whereas in the Examples, by providing a second coating layer formed from an epoxy isocyanate-based composition with excellent waterproof properties on the outer layer side of the first coating layer, deterioration of the first coating layer caused by water (especially steam) is suppressed and the gas barrier properties of the vapor-deposited layer (aluminum oxide layer) can be maintained. As with the Examples, Comparative Examples 1 and 2 have good gas barrier properties. This is believed to be because a PET layer (base layer) with excellent waterproof properties is provided on the outer layer side of the vapor deposition layer (aluminum oxide layer), thereby maintaining the gas barrier properties of the vapor deposition layer (aluminum oxide layer).

[0031] Furthermore, a comparison between the examples and comparative examples revealed that drop strength (impact resistance) could be ensured when no layer other than the adhesive layer was interposed between the CPP layer (heat seal layer) and the PET layer (base layer). The drop strength was low in Comparative Examples 1 and 2, presumably because another layer (particularly the printed layer) was interposed between the CPP layer (heat seal layer) and the PET layer (base layer).

[0032] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the present invention as described in the claims, such as forming the pouch 10 or the laminated film 20 by any combination of the respective configurations of the above or following embodiments or modified examples.

[0033] For example, the pouch 10 of the present invention is not limited to the four-sided sealed type described above, but can be applied to various types of pouches such as a standing pouch, flat pouch, three-sided sealed type, pillow type, gusset type, etc. [Explanation of symbols]

[0034] 10 ··· Pouch 20 ··· Laminated film 30 Heat seal layer 31... Adhesive layer 40 ... base material layer 41 ··· Vapor deposition layer 42 First coating layer 50...Printing layer 51 Second Coating Layer 60 Automatic steam release mechanism 61 Steam release seal 62 Steam release section 63 Steam release section

Claims

1. The film has, in order from the inner layer side, a heat seal layer, an adhesive layer, a substrate layer, a deposition layer, a first coating layer, a printing layer, and a second coating layer, The heat seal layer, the adhesive layer, and the base material layer are laminated together without any other layer therebetween, 13. A laminated film for a pouch, wherein the second coating layer is formed from an epoxy resin, a polyester resin, or an acrylic resin.

2. 2. The laminated film for a pouch according to claim 1, wherein the first coating layer contains at least one of a water-soluble polymer, a metal alkoxide, or a hydrolyzate thereof.

3. The laminated film has an oxygen permeability of 1.0 cc / (m after retorting at 127° C. for 30 minutes. ２ 2. The laminated film for a pouch according to claim 1, characterized in that the film has a rolling resistance of 100% or less.

4. 2. The laminated film for a pouch according to claim 1, wherein the heat seal layer is made of non-oriented polypropylene.

5. A pouch comprising the laminated film according to claim 1 formed into a bag shape.

Images