JP2006205597A - Laminated film and bag comprising it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film having definite or above barrier properties and high falling body impact strength and excellent in opening properties, and a bag using it. <P>SOLUTION: The laminated film is composed of a barrier layer, an intermediate layer comprising a biaxially stretched polyamide resin layer and a seal layer comprising a polypropylene resin layer and these layers are laminated in the order of barrier layer/intermediate layer/seal layer. The oxygen permeability after sterilization under heating and pressure of the laminated film is 1.0 cc/m<SP>2</SP>24h or below. The bag comprising this laminated film is also disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The laminated film of the present invention relates to a film constituting a bag for heat and pressure sterilized food and the bag.

In recent years, food packaging forms that use pouches using plastic films are increasing from conventional cans, bottles, and the like in terms of waste and the like. Moreover, in order to improve the preservability of the contents, materials having various barrier properties are used. Further, it has been demanded that it can be easily opened, that is, easily opened by hand. As a method for meeting these requirements, a technique using a laminated film in which a metal oxide vapor-deposited PET film, a biaxially stretched nylon film, a PET film, and a polypropylene film are laminated in this order is disclosed. (See Patent Document 1)
However, in this configuration, the adhesive strength between the layers is not always sufficient, and there are cases where there is a problem in the drop strength. In addition, the tearability is not always sufficient.
Utility Model Registration No. 3093051

  The present invention provides a laminated film having a barrier property of a certain level or more, a high falling body strength, and an excellent opening property, and a bag formed using the film.

The invention according to claim 1 is a laminated film comprising a barrier layer, an intermediate layer made of a biaxially stretched polyamide resin layer, and a seal layer made of a polypropylene resin layer, and laminated in the order of barrier layer / intermediate layer / seal layer. The laminated film has an oxygen permeability of 1.0 cc / m 2 · 24 h or less after heat and pressure sterilization.
The invention according to claim 2 is the laminated film according to claim 1, wherein the barrier layer is a layer obtained by depositing silicon oxide and / or aluminum oxide on a biaxially stretched polyester base material.
The invention according to claim 3 is the laminated film according to claim 1 or 2, wherein a protective layer is further provided on the barrier layer.
The invention according to claim 4 is the laminated film according to claim 3, wherein a layer formed by depositing silicon oxide and / or aluminum oxide is provided on a surface of the protective layer that is in contact with the barrier layer.
The invention according to claim 5 is a bag for a heat and pressure sterilized food, in which the laminated film according to any one of claims 1 to 4 is used.

  The barrier layer constituting the laminated film of the present invention prevents oxygen in the air from permeating into the bag after sterilization, and prevents alteration of the contents. The material constituting the barrier layer is not particularly limited, and a commonly used material may be used. For example, a metal oxide thin film such as silicon oxide or aluminum oxide is preferably used. These metal oxide thin films are usually formed on a substrate such as a polyethylene terephthalate (PET) film by means such as vapor deposition and used together with the substrate.

The intermediate layer constituting the laminated film of the present invention is a layer used for imparting easy tearability to the laminated film, that is, a layer that can be easily opened by hand or the like, and a biaxially stretched polyamide resin is used. . Biaxially stretched polyamide is preferably used because it exhibits good strength when notched and can be easily torn by notching. Since the biaxially stretched polyamide layer is easily tearable, the laminated film can be easily torn even if a barrier layer and a seal layer are present on both sides of the intermediate layer.
When the intermediate layer made of the biaxially stretched polyamide resin layer is not easily tearable, the bag may be cut obliquely from the notch when the bag is opened, and the contents may leak out.

  The sealing layer constituting the laminated film of the present invention is a layer that is used for stacking the sealing layers so as to face each other, heat-sealing the periphery, and processing into a bag shape. There is no particular limitation as long as it is present, and a material that does not adversely affect the contents or the like may be appropriately selected and used. As a material suitably used for the sealing layer, polypropylene (CPP) resin is suitably used in view of sealing properties, resistance to heat and pressure sterilization, influence on contents, and the like.

In the laminated film of the present invention, the barrier layer, the intermediate layer, and the sealing layer are laminated in this order, and when the sealing layer is made into a bag, it becomes the inside of the bag.
The sealing layer made of CPP resin or the like used in the laminated film of the present invention is not easily tearable, but by being directly laminated on a polyamide resin having good tearability, the sealing layer is also torn simultaneously with the polyamide resin. It becomes easy and the tearability improves as the whole laminated film.
In the present invention, a film in which a metal oxide is vapor-deposited on a PET film is suitably used as the barrier layer and is laminated relative to the intermediate layer. At this time, either side of the barrier layer may be opposed to the intermediate layer, but it is preferably laminated so that the PET film surface of the barrier layer faces the intermediate layer. When the vapor-deposited layer is laminated relative to the intermediate layer, the water vapor permeability of the sealing layer made of CPP or the like and the intermediate layer made of polyamide resin is good when the heat and pressure sterilization treatment is performed. This is because the contained water is heated and easily penetrates through the sealing layer and the polyamide layer to lower the barrier property of the metal oxide layer.
When laminated in this way, the metal oxide vapor deposition layer comes out on the outermost surface, so that it is preferable to provide a protective layer as described later.

In the laminated film of the present invention, it is preferable that a protective layer is further provided on the barrier layer. That is, as described above, when the base film side of the barrier layer is laminated opposite to the intermediate layer, the metal oxide layer of the barrier layer becomes the surface of the laminated film, and the metal oxide layer due to impact, friction, etc. However, the barrier property may be lowered due to deterioration of the metal oxide layer during the heat and pressure sterilization treatment, but the barrier property can be prevented from being lowered by providing a protective layer. Furthermore, the design can be improved by printing the protective layer.
Moreover, barrier property can be further improved by vapor-depositing a metal oxide etc. in the side facing a barrier layer of a protective layer.

  Although it does not specifically limit as said protective layer, The polyester film used as a base material of a barrier layer from intensity | strength, hot water resistance, printability, design property, etc. is used suitably.

  The laminated film of the present invention comprises a barrier layer, an intermediate layer composed of a biaxially stretched polyamide resin layer, and a seal layer composed of a polypropylene resin layer, and is laminated in the order of (protective layer) / barrier layer / intermediate layer / seal layer. The oxygen permeability after retort sterilization of the laminated film is 1.0 cc / m 2 · 24 h or less. If the oxygen permeability after retort sterilization exceeds 1.0 cc / m 2 · 24 h, the contents may be poorly stored and may be difficult to store for a certain period of time. That is, the contents may be altered during storage after sterilization and transportation.

  Although the lamination method of the laminated film of the present invention is not particularly limited, the dry lamination method using an adhesive such as urethane is excellent in heat resistance when performing heat and pressure sterilization treatment after the film forming each layer is formed. Is preferred.

Since the laminated film of the present invention has the above contents, it is possible to provide a laminated film having a barrier property of a certain level or more, a high falling strength, and an excellent openability.
Furthermore, the bag which consists of the said laminated | multilayer film is used suitably for heat-pressurization foodstuffs.

The embodiments of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Moreover, the evaluation method was implemented with the following method.

Example 1
PET film (espet, thickness 12 μm, manufactured by Toyobo Co., Ltd.) as a protective layer, silicon oxide-deposited PET film (tech barrier, thickness 12 μm, manufactured by Mitsubishi Plastics) as a barrier layer, and polyamide film (Harden, thickness, as an intermediate layer) 15μ, manufactured by Toyobo Co., Ltd.), CPP film (pyrene, thickness 60μm, manufactured by Toyobo Co., Ltd.) as the seal layer, and urethane film so that the PET film surface of the barrier layer faces the polyamide film as the intermediate layer A laminated film was obtained by laminating in the order of protective layer / barrier layer / intermediate layer / sealing layer using a system adhesive (Takelac Taketake, manufactured by Mitsui Takeda Chemical Co., Ltd.).
(Example 2)
In Example 1, an aluminum oxide vapor-deposited PET film (barrier rocks, thickness 12 mμ, manufactured by Toray Film Processing Co., Ltd.) was used as the protective layer, and an aluminum oxide vapor-deposited PET film was used as the barrier layer instead of the silicon oxide vapor-deposited PET film. Obtained a laminated film in the same manner as in Example 1.
(Example 3)
In Example 1, a laminated film was obtained in the same manner as in Example 1 except that an aluminum oxide vapor-deposited PET film was used as the protective layer and the vapor-deposited surface of the protective layer was opposed to the vapor-deposited surface of the barrier layer.

Example 4
In Example 2, a laminated film was obtained in the same manner as in Example 2 except that no protective layer was provided and that the PET side of the aluminum oxide vapor-deposited PET film was the outermost layer.
(Comparative Example 1)
In Comparative Example 4, a laminated film was obtained in the same manner as Comparative Example 1 except that a PET film was laminated between the polyamide resin and the CPP film.
(Comparative Example 3)
In Example 1, a laminated film was obtained in the same manner as in Example 1 except that the barrier layer was not used.

Using the laminated film obtained above, the oxygen transmission rate, dropout strength, and tearability were evaluated by the following methods, and the results are shown in Table 1.
(Oxygen permeability)
The laminated film obtained above was subjected to a heat and pressure sterilization treatment at 130 ° C. × 0.25 MPa for 10 minutes, and then at 23 ° C. and 90% with an oxygen permeability measuring machine (OX-TRAN, manufactured by MOCON). The oxygen permeability was measured under the conditions.
(Falling body strength)
Using the laminated film obtained above, a bag filled with 400 g of water with a length of 280 mm, a width of 200 mm, and a seal width of 10 mm was prepared, and after heat and pressure sterilization treatment at 130 ° C. × 0.25 MPa for 10 minutes, 1 From a height of 0.5 m, the product was flattened and evaluated according to the following criteria.
○: Not destroyed.
X: It destroyed.
(Easily tearable)
Using the laminated film obtained above, a bag was produced with a length of 280 mm, a width of 200 mm, and a seal width of 10 mm, and was torn in the easy tear direction of the polyamide film, and evaluated according to the following criteria.
○: It was easily torn linearly.
Δ: Although it was torn, it was torn diagonally
X: It was difficult to tear.

  As shown in Table 1, the Examples showed good results, but Comparative Example 2 without a barrier layer had a high oxygen permeability, and a PET film was provided between the intermediate layer and the seal layer. In Comparative Example 1, the falling body strength and the easy tearability were lowered.

Claims (5)

  A laminated film comprising a barrier layer, an intermediate layer made of a biaxially stretched polyamide resin layer, and a seal layer made of a polypropylene resin layer, and laminated in the order of barrier layer / intermediate layer / seal layer, A laminated film having an oxygen permeability of 1.0 cc / m2 · 24 h or less after heat and autoclaving.   The laminated film according to claim 1, wherein the barrier layer is a layer formed by depositing silicon oxide and / or aluminum oxide on a biaxially stretched polyester base material.   The laminated film according to claim 1, wherein a protective layer is further provided on the barrier layer.   The laminated film according to claim 3, wherein a layer formed by depositing silicon oxide and / or aluminum oxide is provided on a surface of the protective layer that is in contact with the barrier layer.   A bag for heat and pressure sterilized food, wherein the laminated film according to any one of claims 1 to 4 is used.