JP2013052532A - Laminated film and manufacturing method of laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film containing a polylactic acid resin, which has an improved peeling resistance.SOLUTION: The laminated film comprises a sealant layer 1, a biodegradable layer 2 made of the polylactic acid resin laminated on the sealant layer 1, and a base material layer 3 made of any one of polyethylene terephthalate, nylon and drawn polypropylene laminated on the biodegradable layer.

Description

  The present invention relates to a laminated film and a method for producing the same, and more particularly to a laminated film containing a polylactic acid resin and a method for producing the same.

2. Description of the Related Art Conventionally, biomass plastic produced by using biological resources instead of fossil resources has attracted attention, and in particular, industrial use of biomass plastics having biodegradability is required.
A polylactic acid (PLA) resin is a polymer of lactic acids obtained by fermenting a plant-derived raw material, and is one of biodegradable biomass plastics. Since this polylactic acid resin is excellent in transparency and has a property that it is difficult for odors to adhere to it, attempts have been made to introduce it into food packaging films.

  As a technique for introducing a polylactic acid resin into such a packaging film, for example, as disclosed in Patent Document 1, a plurality of film-like layers constituting the packaging film contain a layer made of a polylactic acid resin. Laminated films have been proposed.

JP 2008-247018 A

  In the laminated film shown in Patent Document 1, the layer made of polylactic acid resin is bonded to the layer made of polylactic acid resin by using a resin having an appropriate molding temperature with respect to the polylactic acid resin. It can be included. However, for example, when an external force such as twisting is applied to a food packaging bag using a laminated film, the polylactic acid resin layer and other layers may be peeled off, and the adhesive force is sufficient. I could not say.

  This invention was made in order to solve such a conventional problem, and it aims at providing the laminated film which improved the peel resistance of the laminated film containing polylactic acid resin, and its manufacturing method. To do.

  The laminated film according to the present invention comprises a sealant layer, a biodegradable layer made of a polylactic acid resin laminated on the sealant layer, and polyethylene terephthalate, nylon, or stretched polypropylene laminated on the biodegradable layer. And a base material layer made of any one kind.

Here, the sealant layer is preferably made of unstretched polypropylene. Moreover, a vapor deposition layer can be formed on the surface of the base material layer.
As a vapor deposition layer, silica vapor deposition, alumina vapor deposition, aluminum vapor deposition, etc. can be mentioned, and since it can be processed transparently and barrier property improves more, it is preferred to use silica vapor deposition.
Moreover, it is preferable that the thickness of the sealant layer is 20 to 40 μm, the thickness of the biodegradable layer is 15 to 35 μm, and the thickness of the base material layer is 5 to 30 μm.

The food packaging bag according to the present invention is formed from the laminated film described in any of the above, and has the base material layer on the outside and the sealant layer on the inside.
The method for producing a laminated film according to the present invention is a laminated film producing method for producing the laminated film described above, wherein the biodegradable layer is bonded onto the surface of the sealant layer, and the surface of the biodegradable layer is formed. An adhesive is applied, and the base material layer is bonded onto the surface of the biodegradable layer by the adhesive.

  According to this invention, since the base material layer, the biodegradable layer, and the sealant layer are sequentially laminated, it is possible to improve the peel resistance of the laminated film containing the polylactic acid resin.

It is sectional drawing which shows the structure of the laminated film which concerns on one embodiment of this invention. It is sectional drawing which shows the structure of the laminated | multilayer film in which the vapor deposition layer was formed.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, the structure of the laminated film which concerns on one embodiment of this invention is shown. The laminated film includes a sealant layer 1, a biodegradable layer 2 made of polylactic acid (PLA) resin laminated on the sealant layer 1, polyethylene terephthalate (PET) laminated on the biodegradable layer 2, nylon, Or it has the base material layer 3 which consists of any 1 type of an expanded polypropylene.

The sealant layer 1 is formed from a resin material having heat sealing properties such as unstretched polypropylene (CPP), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polyethylene (PE), and a laminated film is formed. When processed into a food packaging bag or the like, it forms an inner surface exposed to the inside. The biodegradable layer 2 is located between the sealant layer 1 and the base material layer 3 and has biodegradability. The base material layer 3 has a barrier property that blocks intrusion of gas and liquid, and constitutes an outer surface exposed to the outside when the laminated film is processed into a food packaging bag or the like.
Thus, the peeling resistance of the laminated film is improved by laminating the sealant layer 1, the biodegradable layer 2, and the base material layer 3 in this order, or the base material layer 3, the biodegradable layer 2, and the sealant layer 1 in this order. Can be made.

  In the laminated film, the thickness of the sealant layer 1 is preferably 20 to 40 μm, the thickness of the biodegradable layer 2 is preferably 15 to 35 μm, and the thickness of the base material layer 3 is preferably 5 to 30 μm. By forming each layer with such a thickness, the peel resistance of the laminated film can be further improved.

  As shown in FIG. 2, the base material layer 3 can also form the vapor deposition layer 4 on the surface bonded with the biodegradation layer 2 by silica vapor deposition, alumina vapor deposition, aluminum vapor deposition, or the like. This vapor deposition layer 4 can improve the barrier property of the base material layer 3. In addition, as the vapor deposition layer 4, since it can process to transparency and barrier property improves more, it is preferable to set it as silica vapor deposition.

Next, the manufacturing method of the laminated film shown in FIG. 1 is demonstrated.
The biodegradable layer 2 made of a polylactic acid resin is brought into contact with the surface of the sealant layer 1 made of a resin material having heat sealability, and both are bonded by dry lamination. Then, after apply | coating an adhesive agent on the surface of the base material layer 3 which consists of a polyethylene terephthalate, nylon, or an extending | stretching polypropylene, the base material layer 3 is joined on the surface of the biodegradable layer 2 with the adhesive agent. Thus, the adhesiveness between the biodegradable layer 2 and the base material layer 3 can be further improved by adhering the base material layer 3 coated with an adhesive to the biodegradable layer 2.
Thus, the laminated film with improved adhesion between the base material layer 3 and the biodegradable layer 2 is processed into a food packaging bag or the like with the base material layer 3 on the outside and the sealant layer 1 on the inside. The

  Next, an example in which the adhesive strength between the biodegradable layer and the base material layer was actually measured will be described. In this example, a laminated film in which a base material layer having a thickness of 12 μm, a biodegradable layer having a thickness of 15 μm, and a sealant layer having a thickness of 30 μm are sequentially laminated is used.

  In addition, as a comparative example, the order of lamination is changed from that of the above example, and a biodegradable layer having a thickness of 15 μm, a base material layer having a thickness of 12 μm, and a sealant layer having a thickness of 30 μm. A laminated film that was sequentially laminated was used.

  And as a result of measuring the adhesive strength of the biodegradable layer to the base material layer using the laminated film of the example, and the adhesive strength of the biodegradable layer to the base material layer using the laminated film of the comparative example, respectively, the adhesion of the example The strength was 2.76 (N / 15 mm), whereas the adhesive strength of the comparative example was 1.61 (N / 15 mm). Thereby, it turned out that the peeling resistance of a laminated | multilayer film improves by laminating | stacking in order of a sealant layer, a biodegradable layer, and a base material layer.

  The adhesive strength was 15 mm width, and the tensile strength (N) was measured when peeling occurred between the biodegradable layer and the base material layer in a direction with a peeling angle of 180 degrees and a tensile speed of 300 mm / min. Is.

  In the examples, the thickness of the base material layer is changed in the range of 5 to 30 μm, the thickness of the biodegradable layer is changed in the range of 15 to 35 μm, and the thickness of the sealant layer is changed in the range of 20 to 40 μm. It was. As a result, when the thickness of each layer was in the above range, superior adhesiveness was seen compared to the comparative example. Further, for the examples, a laminated film in which a base material layer is adhered and laminated to a biodegradable layer coated with an adhesive, and a laminated film in which a biodegradable layer is adhered to and laminated on a base material layer coated with an adhesive As a result of comparison, it was also found that the adhesion between the biodegradable layer and the base material layer was improved by the latter laminated film.

  1 sealant layer, 2 biodegradable layer, 3 substrate layer, 4 deposited layer.

Claims (6)

A sealant layer,
A biodegradable layer made of polylactic acid resin laminated on the sealant layer;
A laminated film comprising: a base material layer made of polyethylene terephthalate, nylon, or stretched polypropylene laminated on the biodegradable layer.   The laminated film according to claim 1, wherein the sealant layer is made of unstretched polypropylene.   The laminated film according to claim 1, wherein a vapor deposition layer is formed on the surface of the base material layer.   4. The thickness of the sealant layer is 20 to 40 μm, the thickness of the biodegradable layer is 15 to 35 μm, and the thickness of the base material layer is 5 to 30 μm. A laminated film according to 1.   A food packaging bag formed from the laminated film according to any one of claims 1 to 4, wherein the base material layer is on the outside and the sealant layer is on the inside. It is a laminated film manufacturing method which manufactures the laminated film of Claims 1-4,
Bonding the biodegradable layer on the surface of the sealant layer;
Applying an adhesive on the surface of the base material layer,
The laminated film manufacturing method which joins the said base material layer on the surface of the said biodegradable layer with the said adhesive agent.

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