JP4719362B2 - Sealant film with excellent anti-fogging properties - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealant film bonded to a base film by a dry laminating method, and more specifically, exhibits excellent antifogging properties even after being bonded to a base film using an adhesive. It relates to a sealant film.
[0002]
[Prior art]
It is preferable that the package of moisture-containing food or the like has antifogging properties so that dew does not adhere to the inner surface of the package. Therefore, an antifogging laminate film in which a sealant film containing an antifogging agent is bonded to a base film using an adhesive is used. In general, a single layer film or a multilayer film made of a polyolefin resin such as a polyethylene resin or a polypropylene resin is used as the sealant film.
However, when a polyolefin resin sealant film containing an antifogging agent is bonded to a base film via an adhesive, the antifogging property of the sealant film has been greatly reduced.
[0003]
[Problems to be solved by the invention]
The present invention intends to provide a sealant film in which the antifogging property does not decrease even when bonded to a base film by a dry laminating method.
Another object of the present invention is to provide a sealant film that has a heat shrinkability or a heat shrinkability that has been subjected to a stretching treatment that does not reduce the antifogging property even when bonded to a base film by a dry laminating method.
[0004]
In order to solve the above problems, the present invention has taken the following measures. That is, a sealant film for bonding to a base film to form a laminate film, and an ethylene-vinyl acetate copolymer via a modified polyolefin resin layer on one side of a polyolefin resin layer containing an antifogging agent A saponified product layer and a polyamide-based resin layer are laminated in this order by a coextrusion method. The thickness of the saponified product layer of ethylene-vinyl acetate copolymer is 1 to 15 μm, the saponified product layer of ethylene-vinyl acetate copolymer, polyamide A sealant film excellent in anti-fogging property , wherein the total thickness of both layers of the resin-based resin layer is 6 μm or more, and the thickness of the polyamide-based resin layer is 5 to 50 μm. Preferably, a polyolefin resin layer containing an antifogging agent, a modified polyolefin resin layer, a saponified ethylene-vinyl acetate copolymer layer, and a polyamide resin layer are laminated in this order by a coextrusion method. Further, after being laminated by a co-extrusion method, the film is stretched to impart heat shrinkability. Further, after being laminated and stretched by a coextrusion method, heat shrinkage is removed by heat treatment.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the polyolefin resin used in the polyolefin resin layer containing the antifogging agent of the present invention include a high pressure method low density polyethylene resin, a low pressure method high density polyethylene resin, a linear low density polyethylene resin, and an ethylene-vinyl acetate copolymer. An ethylene resin such as a coalescence or a propylene resin such as a polypropylene resin or an ethylene-propylene copolymer is used.
In addition, the polyolefin resin layer may be a mixture of two or more types as well as one type of these resins. The polyolefin resin layer may be a single layer or a multilayer.
[0006]
The thickness of the polyolefin resin layer containing the antifogging agent is not particularly limited, but is preferably 3 to 50 μm. If the thickness of the polyolefin resin layer is less than 3 μm, it may be difficult to impart good sealing properties to the laminate film bonded with the sealant film. On the other hand, if the thickness of the polyolefin resin layer exceeds 50 μm, the resulting laminate film becomes too thick, which may not be preferable as a packaging film for foods and the like.
[0007]
The antifogging agent to be contained in the polyolefin resin layer is not particularly limited, and an antifogging agent conventionally used for an antifogging film can be used as it is. For example, diglycerol monolaurate, glycerol monooleate, diglycerol monooleate, diglycerol sesquilaurate, diglycerol sesquioleate, monoglycerol monolaurate, monoglycerol monooleate, etc. Polyethylene glycol fatty acid ester antifogging agents such as glycol monolaurate and polyethylene glycol monooleate, polyethylene glycol alkyl ether antifogging agents such as polyoxyethylene lauryl alcohol ether and polyoxyethylene lauryl alcohol ether, and stearyl Alkyl alcohol antifogging agents such as alcohol and oleic alcohol are preferably used. These antifogging agents can be used alone or in combination of two or more.
[0008]
The amount of the antifogging agent to be contained in the polyolefin resin layer is not particularly limited, but is preferably 3000 to 50000 ppm. If the content of the antifogging agent is less than 3000 ppm, it may be difficult to exhibit good antifogging properties. On the other hand, if it exceeds 50000 ppm, not only the production cost increases, but also the adhesiveness with the modified polyolefin resin layer laminated on the polyolefin resin layer may be lowered, which is not preferable.
[0009]
Examples of the modified polyolefin resin to be laminated on one side of the polyolefin resin layer containing the antifogging agent include ethylene, propylene, ethylene-α-olefin copolymer, or propylene-α-olefin copolymer and unsaturated carboxylic acid. Alternatively, a copolymer in which a polar group is introduced by graft polymerization of a derivative thereof is used. Unsaturated carboxylic acids or derivatives thereof are unsaturated compounds having a carboxylic acid group, an acid anhydride group, an ester group, a carboxylic acid amide group, etc., and specific examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid , Itaconic acid, acrylic anhydride, methacrylic anhydride, maleic anhydride, itaconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, maleic acid monomethyl ester, maleic acid monoethyl ester, acrylamide , Methacrylamide and the like.
[0010]
The thickness of the modified polyolefin resin layer is not particularly limited, but is preferably 1 to 10 μm. When the thickness of the modified polyolefin resin layer is less than 1 μm, the adhesion between the polyolefin resin layer and the saponified ethylene-vinyl acetate copolymer layer or the polyamide resin layer may not be good. On the other hand, if it exceeds 10 μm, the production cost is increased.
[0011]
In the present invention, a saponified ethylene-vinyl acetate copolymer layer and / or a polyamide resin layer is laminated on one side of a polyolefin resin layer containing an antifogging agent via a modified polyolefin resin layer. Is the biggest feature.
For the ethylene-vinyl acetate copolymer saponified product layer, an ethylene-vinyl acetate copolymer saponified product having an ethylene content of 28 to 50 mol% and a saponification degree of 95% or more is suitably used.
Further, nylon-6, nylon-66, nylon 12, or a copolymer thereof can be used for the polyamide resin layer.
[0012]
The thickness of the saponified ethylene-vinyl acetate copolymer layer is not particularly limited, but is preferably 1 to 15 μm. If the thickness of the saponified ethylene-vinyl acetate copolymer layer is less than 1 μm, not only gas barrier properties cannot be imparted, but also the antifogging property of the polyolefin resin layer when bonded to a substrate film. It may be difficult to maintain. On the other hand, if it exceeds 15 μm, the production cost is increased.
The thickness of the polyamide resin layer is not particularly limited, but is preferably 5 to 50 μm. When the thickness of the polyamide resin layer is less than 5 μm, not only good mechanical strength can be obtained, but also it becomes difficult to maintain the antifogging property of the polyolefin resin layer when bonded to the base film. There is a case. On the other hand, if it exceeds 50 μm, the production cost is increased.
[0013]
In addition, when the sealant film excellent in antifogging property of the present invention has both the saponified ethylene-vinyl acetate copolymer layer and the polyamide resin layer, the total thickness of both layers may be 6 μm or more. It is desirable for maintaining good antifogging property of the polyolefin resin layer when bonded to the base film.
The thickness of the sealant film excellent in antifogging property of the present invention is preferably 10 to 100 μm.
[0014]
The sealant film excellent in antifogging property of the present invention is formed by an inflation method by a normal coextrusion method or a T-die method.
For example, using four extruders and four types of four-layer circular dies, the layer structure includes a polyolefin resin layer containing an antifogging agent, a modified polyolefin resin layer, a saponified ethylene-vinyl acetate copolymer layer, a polyamide Co-extrusion can be performed in the order of the resin layers, and film formation can be performed by an inflation method.
[0015]
The coextruded film can be stretched to obtain a film having heat shrinkability. For example, heat shrinkability can be imparted by a biaxial stretching method using an inflation method.
In addition, the coextruded film can be obtained by subjecting it to a heat treatment after the stretching treatment, thereby obtaining a film having no heat shrinkability. For example, the heat shrinkability of the stretched film can be removed by applying relaxation and heat to the stretched film.
[0016]
The sealant film excellent in antifogging property of the present invention is bonded to a base film by a dry laminating method using an adhesive such as a polyurethane adhesive. Of course, when bonding with a base film, a base film is bonded on the surface on the opposite side to the polyolefin resin layer containing an antifogging agent.
[0017]
The base film is not particularly limited, and a film generally used for dry lamination can be used.
In particular, when the sealant film excellent in antifogging property of the present invention has a saponified ethylene-vinyl acetate copolymer layer, a film having no gas barrier property may be used as the base film. A laminated film having excellent gas barrier properties can be obtained. In addition, when the sealant film having excellent antifogging property of the present invention has a polyamide resin layer, a laminate film having excellent mechanical strength can be obtained even if a film having poor mechanical strength is used as the base film. Obtainable.
[0018]
Moreover, when the sealant film excellent in antifogging property of the present invention is imparted with heat shrinkability by stretching treatment, the resulting laminate film can be imparted with heat shrinkability, and after being stretched. When heat shrinkage is removed by heat treatment, mechanical strength can be imparted to the resulting laminate film.
[0019]
[Action]
When a sealant film consisting only of a polyolefin resin containing an antifogging agent is bonded to a base film through an adhesive, the antifogging property of the surface to be sealed is reduced. It is thought that the amount of bleed on the surface to be sealed is reduced because the clouding agent moves to the adhesive layer.
On the other hand, when the sealant film excellent in antifogging property of the present invention is bonded to the base film through the adhesive layer, the reason why the antifogging property of the surface to be sealed is not lowered is not clear, but the antifogging agent The saponified ethylene-vinyl acetate copolymer layer and / or the polyamide layer existing between the polyolefin-based resin layer and the adhesive layer containing the anti-fogging agent is transferred to the adhesive layer. It is thought that it is easy to bleed to the surface to be pressed and sealed with the antifogging agent.
[0020]
【Example】
Hereinafter, the content of the present invention will be described more specifically with reference to examples and comparative examples.
In addition, the antifogging property in this invention was measured with the following method.
(Anti-fogging property)
First, 200 cc of 80 ° C. hot water is put into a 500 cc beaker, and the mouth of the beaker is covered with a sample film so that the measurement surface is on the inside, and sealed with a rubber band. Then, the beaker whose mouth is covered with the sample film is put in a thermostatic chamber at 23 ° C. After 5 minutes, 15 minutes, 30 minutes, and 60 minutes, the dew adhering to the measurement surface of the sample film Observe the condition. The observation results show that the film surface is covered with small water droplets and appears silvery, “X”, the water droplets are slightly larger but not visible in the “△” state, and the water droplets are larger and the inside is somewhat visible. Is indicated by “□”, a state in which the water droplet becomes larger and the inside can be seen as “◯”, and a state in which the water droplet does not adhere and is transparent and the inside can be clearly seen is indicated by “」 ”.
[0021]
[Example 1]
Using four extruders and four types of four-layer circular dies, from the innermost layer to the antifoggant-containing polyolefin resin layer, the modified polyolefin resin layer, the saponified ethylene-vinyl acetate copolymer layer, and the polyamide resin layer The unstretched raw fabrics laminated in this order were coextruded. The obtained laminated unstretched original fabric was reheated and subjected to a stretching treatment of 3.5 times in both the machine direction and the transverse direction to obtain a sealant film having heat shrinkability and excellent antifogging property.
The obtained sealant film had an antifogging agent-containing polyolefin resin layer of 20 μm, a modified polyolefin resin layer of 3 μm, an ethylene-vinyl acetate copolymer saponified product layer of 4 μm, and a polyamide resin layer of 6 μm.
[0022]
As an antifogging agent, 15,000 ppm of a polyglycerin fatty acid ether antifogging agent made by Takemoto Yushi is used, and as a polyolefin resin, a linear low-density polyethylene resin manufactured by Sumitomo Chemical: Sumikasen α FZ201-0 (density) : 0.912 g / cm ³ , MI: 2.0 g / 10 min).
Moreover, as modified polyolefin-type resin, the Mitsui Chemicals adhesive resin: Admer NF550 was used.
Further, Soarnol DC3203 manufactured by Nippon Synthetic Chemical Industry was used as the saponified ethylene-vinyl acetate copolymer, and UBE 5034B manufactured by Ube Industries was used as the polyamide resin.
[0023]
The obtained heat-shrinkable sealant film having excellent anti-fogging properties is bonded to a biaxially stretched polypropylene film (thickness: 20 μm) by a dry laminating method using an adhesive: Takenate A515 manufactured by Takeda Pharmaceutical Co., Ltd. An antifogging laminate film having shrinkage was obtained.
The anti-fogging property (surface of the antifoggant-containing polyolefin resin layer) of the obtained laminate film was “◯” after 5 minutes, “◎” after 15 minutes, and “◎” after 30 minutes. In contrast, the anti-fogging property of the same sealant film formed simultaneously with the sealant film used for the laminate film was “◯” after 5 minutes, “◎” after 15 minutes, and “◎” after 30 minutes. It was.
In other words, even when the sealant film of the present invention was bonded to a base film through an adhesive, no decrease in antifogging property was observed.
The antifogging property of the laminate film was evaluated 30 days after being bonded to the base film, and the antifogging property of the sealant film was also evaluated at the same time as the laminate film.
The heat shrinkability of the laminate film is 10% in the vertical direction and 10% in the horizontal direction in 90 ° C. warm water, and the heat shrinkability of the sealant film is 30% in the vertical direction and 30% in the hot water at 90 ° C. %Met.
[0024]
[Comparative Example 1]
Using one extruder and a single-layer circular die, a sealant film having a thickness of 20 μm made of only a polyolefin-based resin containing an antifogging agent was formed by an inflation method.
As in Example 1, the anti-fogging agent is 15000 ppm of polyglycerin fatty acid ester anti-fogging agent manufactured by Takemoto Yushi, and the polyolefin resin is the same as that in Example 1 and is manufactured by Sumitomo Chemical. Linear low-density polyethylene resin: Sumikasen FZ-201-0 (density: 0.912 g / cm ³ , MI: 2.0 g / 10 min) was used.
[0025]
The obtained sealant film was bonded to biaxially oriented polypropylene (thickness: 20 μm) by a dry laminating method using an adhesive: Takenate A515 manufactured by Takeda Pharmaceutical Co., Ltd. as in Example 1 to obtain an antifogging laminate film. It was.
The anti-fogging property (surface of the polyolefin resin layer containing the anti-fogging agent) of the obtained laminate film was “x” after 5 minutes, “Δ” after 15 minutes, and “Δ” after 30 minutes. In contrast, the anti-fogging property of the same sealant film formed simultaneously with the sealant film used for the laminate film was “◯” after 5 minutes, “◎” after 15 minutes, and “◎” after 30 minutes. It was.
That is, when the sealant film of Comparative Example 1 was bonded to the base film through an adhesive, the antifogging property was greatly reduced.
In addition, the anti-fogging evaluation of the laminate film and the sealant film was performed under the same conditions as in Example 1.
[0026]
【effect】
The sealant film excellent in antifogging property of the present invention does not decrease the antifogging property even if it is bonded to a base film by a dry laminating method using an adhesive, so that a laminate film excellent in antifogging property can be obtained. it can. Therefore, the laminate film using the sealant film of the present invention can obtain a transparent and excellent display body without depositing dew on the inner surface of the package body even when packaging foods containing moisture. .
[0027]
For example, a laminating film with a heat-shrinkable sealant film with excellent anti-fogging properties does not cause dew to adhere to the inner surface of the lid when it is used as a cup lid and is subjected to a heat shrink treatment. As a result, wrinkles disappear and a cup excellent in display is obtained.
In addition, the laminating film bonded with the anti-fogging sealant film excluding the heat shrinkability after being stretched, when used for a bag-shaped package, does not cause dew to adhere to the inner surface of the bag, A bag-like package excellent in display can be obtained.

Claims (3)

A sealant film for laminating a base film to form a laminate film,
A saponified ethylene-vinyl acetate copolymer layer and a polyamide resin layer are laminated in this order by a coextrusion method on one side of a polyolefin resin layer containing an antifogging agent via a modified polyolefin resin layer. -The thickness of the vinyl acetate copolymer saponification layer is 1 to 15 µm, the total thickness of both the ethylene-vinyl acetate copolymer saponification layer and the polyamide resin layer is 6 µm or more, and the polyamide resin layer A sealant film excellent in anti-fogging property, wherein the thickness is 5 to 50 μm. 2. The sealant film having excellent antifogging properties according to claim 1, wherein the film is laminated by a coextrusion method and then stretched to impart heat shrinkability. The sealant film having excellent antifogging properties according to claim 1, wherein the heat shrinkability is removed by heat treatment after being laminated and stretched by a coextrusion method.