JPH06340044A - Film for anti-fogging packing material - Google Patents

Abstract

PURPOSE:To improve anti-fogging properties, to enhance heat-seal strength and to make content easy to look by making dew condensation hard to generate by forming an intermediate barrier layer containing an anti-fogging agent between a film being a support substrate to which back printing is applied and an anti-fogging film. CONSTITUTION:An anti-fogging polyolefin film 6 containing an ionic surfactant and a film being a support substrate 1 to which back printing is applied are combined. In this case, an intermediate barrier layer 5 is interposed so as to prevent the attack of an adhesive layer by the surfactant. The intermediate barrier layer 5 prevents the ionic surfactant precipitated from the anti-fogging polyolefin film from penetrating into the adhesive layer and the oxygen permeability thereof is pref. 100cc/m<2>.24hrs or less and the haize thereof is pref. 25% or less in order to hold the transparency of a composite packing material. The intermediate barrier layer 5 is formed by the co-extrusion of a layer composed of polyester or nylon and a layer composed of polyethylene or polypropylene through an adhesive resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent laminated film for food packaging, and more particularly, products such as sliced ham, wieners and sausages containing a large amount of water are packaged in a transparent plastic film and stored at a low temperature in stores. The present invention relates to a film for an anti-fog packaging material that prevents the product from being difficult to see due to the dew condensation of the packaging material when it is sold.

[0002]

2. Description of the Related Art Conventionally, when a food containing a large amount of water is hermetically packaged in a transparent film for sale, the hydrophobic polyolefin film layer used on the inner surface of the packaging material is made of non-reactive water to prevent dew condensation. Known ionic surfactants are those containing 0.1 to 5% of a mixture of 1 or 2 or more of glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylphenyl ether and the like. This anti-fog polyolefin film has been laminated on a printing film which is a supporting substrate and has been used for the above purpose. However, the antifogging effect when using this kind of nonionic surfactant was not always sufficient.

Alkyl sulfonates, alkyl benzene sulfonates, sodium alkylnaphthalene sulfonates, ionic surfactants having excellent anti-fogging effect,
Examples include sodium dialkyl sulfosuccinate, alkyl sulphate, polyoxyethylene alkyl phosphate, N-acyl sarcosine.

[0004]

However, when the polyolefin film containing these ionic surfactants is composite-processed with the supporting substrate film, the surfactant deposited on the film interface is applied to the film of the supporting substrate 1. Reacts with the anchor coating agent or the active ingredient of the adhesive,
Alternatively, it was not put to practical use because it dissolves, hinders the curing action of the adhesive, and causes peeling adhesion failure.

As a means for solving such adhesion failure, it is also possible to interpose a polyolefin film between the supporting base film and the anti-fog polyolefin film as in the invention disclosed in Japanese Patent Publication No. 60-40384. It is carried out between traders. However, a stable adhesive effect can be obtained even if the method described in Japanese Patent Publication No. 60-40384 is used for a polyolefin film which has an excellent antifogging effect, that is, which contains an ionic surfactant that is easy to deposit. However, a peeling phenomenon may occur.

Further, a reaction-curable adhesive is applied to a supporting substrate film, laminated with a polyolefin film, and completely cured by heating and aging. After complete curing, a polyolefin film containing the same ionic surfactant property as that of the polyolefin film. There is also a method of extrusion coating a resin. The present technology has a two-step composite step and requires the second step after completion of the adhesive curing reaction in the first step, resulting in poor production efficiency.

[0007]

As a means for solving the above-mentioned peeling phenomenon, as a result of earnest research, as a result, an antifogging polyolefin layer 6 containing an ionic surfactant and a film of a backing-printed support substrate 1 were combined. In this case, the intermediate barrier layer 5 is interposed so that the adhesive layer is not attacked by the surfactant, and a packaging material excellent in antifogging property, transparency and sealing property is constituted.

The intermediate barrier layer 5 prevents the ionic surfactant deposited from the antifogging polyolefin film 6 from penetrating into the adhesive layer and has an oxygen permeability of 100 cc.
/ m ² · 24hrs. or less, and the haze is 25% or less in order to maintain the transparency of the composite packaging material. Further, by using a printing film of the supporting substrate 1 and a tandem type extrusion laminator, it is possible to perform a Saint-German lamination with a polyolefin resin and to coat the anti-fog polyolefin layer 6 directly on the intermediate barrier layer by coating on both sides. Composed of polyolefin.

The intermediate barrier layer has an oxygen permeability of 100 cc / m ² · 2
4 hrs. Any one of the following polyester, nylon, polyvinyl alcohol, saponified product of polyvinyl alcohol / vinyl acetate copolymer, polyethylene or polypropylene, and acid polymer, ethylene / α-olefin copolymer and polyolefin A film is formed by a coextrusion method through an adhesive resin such as a blend resin.

The general constituent materials used in the present invention will be described below. In the present invention, the supporting substrate 1 serving as the surface layer is made of a biaxially stretched polyester film, a biaxially stretched polypropylene film, a biaxially stretched nylon film, cellophane, etc., which are excellent in printability. Oxygen permeability
Films coated with vinylidene chloride are also used for packaging materials that require less than 30cc / m ² · 24hrs. The thickness is preferably in the range of 12 to 25μ. If it is 12 μm or less, stable printing / laminating may not be performed, which is not preferable. On the other hand, when it exceeds 25 μ, not only the cost becomes high, but also the film becomes hard and the suitability for packaging machine becomes poor.

The polyolefin layer serving as the adhesive layer 4 for extruding the printed base film 1 and the intermediate barrier layer 5 and performing the Saint-German lamination with a laminator has a density of 0.918 to 0.925 and a melt index of 3.5.
Use low density polyethylene with physical properties of ~ 12.0.
When the base polymer of the anti-fog polyolefin film 6 is a polypropylene resin, the compounding with the intermediate barrier layer may be carried out by means of the Saint-German lamination in the second unit of the tandem type extrusion laminator. As the polyolefin resin, a blended resin layer of ethylene / α-olefin copolymer and polyolefin is used.

The anchor coating agent 2 used for adhering a blend resin of ethylene / α-olefin copolymer and polyolefin in the vicinity of the printed support substrate 1 or polyethylene is generally used in water resistance by those skilled in the art. The anchor coating agent of can be used. For example, there are polyester-isocyanate, polyether-isocyanate, and isocyanate-based anchor coating agents.

The intermediate barrier layer 3 has an oxygen permeability of 100 cc / m ²
24 hours or less, any one of polyester, nylon, polyvinyl alcohol, saponification product of polyvinyl alcohol / vinyl acetate copolymer having a haze of 25% or less, and polyethylene, linear low density polyethylene or polypropylene, acid A polymer, a blend resin of ethylene / α-olefin copolymer / polyolefin, and a partially saponified product of an ethylene-vinyl acetate copolymer, which is formed by a coextrusion method through an adhesive resin.
These co-extruded multilayer films are not only unstretched,
A uniaxially or biaxially stretched film can also be used.

Polyolefin as the base polymer of the anti-fog polyolefin layer 6 includes low density polyethylene, linear low density polyethylene, polypropylene, polyethylene / vinyl acetate copolymer polymer, medium density polyethylene, polyethylene / acrylic acid, ionomer, etc. It can be selected according to the application of the material.

The antifogging agent used in the present invention is an alkyl sulfonate, an alkylbenzene sulfonate, a sodium alkylnaphthalene sulfonate, a sodium dialkyl sulfosuccinate, which is an ionic surfactant excellent in antifogging curing. It is N-acyl sarcosine. The content of these surfactants is suitably 0.1 to 0.5%. Incidentally, in the present invention, even if a nonionic surfactant is used as in the case of the above ionic surfactant, the same action and effect as to the adhesion are obtained.

Each of the supporting substrate 1, the intermediate barrier layer 5, and the antifogging polyolefin film 6 can be combined with three kinds of films in one step by using a (tandem type extrusion laminator) for processing a plastic film. The anti-fog polyolefin layer 6 can be formed into a film by extrusion coating from the second extruding unit of the tandem type extrusion laminator, or can be combined with another anti-fog polyolefin film produced by Saint-German lamination to form a composite.

[0016]

According to the constitution of the present invention, the antifogging agent deposited from the polyolefin layer containing an ionic surfactant having an excellent antifogging effect does not hinder the curing of the anchor coating agent layer due to the intermediate barrier layer. An anti-fog packaging material with adhesion is obtained.

Next, an example of the present invention will be described together with a comparative example regarding a film for anti-fog packaging material composed of a composite of the following materials. "Supporting substrate" Biaxially stretched polyester film E510
0 12μ (Toyobo Co., Ltd.) Print on corona treated surface. "Anchor coating agent" Coronate L (Nippon Polyurethane Co., Ltd.) ether isocyanate "Intermediate barrier layer" Flexirap B type (Gunze Co., Ltd.) A linear polyethylene and nylon coextrusion film having the following characteristics. Oxygen permeability 50cc / m ² · 24hrs. Haze 18% Using integrating sphere type light transmittance measuring device JIS K 7105 “Anti-fog Polyolefin A” Polyethylene containing ionic surfactant sodium dodecyl sulfonate 0.2% “Anti-fog Polyolefin B” Nonionic Surfactant Polyoxyethylene Dorfenyl Ether 0.2% Polyethylene

[0018]

[Example] Gravure printing was applied to the corona-treated surface of the supporting substrate 1, the polyester film, and the anchor coating agent 2 was applied to the printing surface using a tandem type extrusion laminator, and then the intermediate barrier layer 5 was combined with the first unit. Thereafter, the antifogging property Polyolefin A (6) is extruded and coated in the second unit on the same line to a thickness of 30 μm. The adhesive polyolefin 4 between the supporting substrate and the barrier layer was made of low-density polyethylene 15μ to obtain the film for anti-fog packaging material of the present invention.

[0019]

[Comparative example]

(Comparative Example 1) Gravure printing was applied to the corona-treated surface of the polyester film which is the supporting substrate 1, the tandem type extrusion laminator was used, and the anchor coating agent 2 was applied to the printing surface, and then the intermediate barrier layer 5 was used as the first unit. After the compounding, the antifogging Polyolefin B (6a) is extruded and coated with a second unit on the same line to a thickness of 30 μm. The adhesive polyolefin 4 used between the supporting substrate and the intermediate barrier layer was low density polyethylene 15μ. The film for the anti-fog packaging material of the comparative example is different from the example in that the anti-fog agent of the anti-fog polyolefin is the former ionic surfactant, whereas the non-ionic surfactant is used. Got

Comparative Example 2 After the gravure printing on the polyester film which is the supporting substrate 1 as described in the example, a tandem type extrusion laminator was used and the anchor coating agent 3 was applied on the printing surface. It is coated with a thickness of 15μ density polyethylene, and 30μ of anti-fog polyolefin A is added on the second unit on the same line.
To obtain a film for anti-fog packaging material of Comparative Example. The difference from the example is that an antifogging film containing an ionic surfactant was formed without an intermediate barrier layer interposed.

Comparative Example 3 After printing on the supporting substrate 1 as described in the example, an anchor coating agent was applied to the printed surface using a tandem type extrusion laminator, and then the first unit had a thickness of 15 μm of low density polyethylene. Then, a second unit in the same line was coated with anti-fog polyolefin B at a thickness of 30 μm to obtain a film for anti-fog packaging material of Comparative Example. This example is different from the example in that the intermediate barrier layer 4 is not present, and the conventional technique in which the antifogging agent is a nonionic surfactant (Japanese Patent Publication No. 60-40384).
No.)

Table 1 shows the antifogging effect and the adhesion effect of these Examples and Comparative Examples 1 to 3 together with the outline of the constitution.

[Table 1] Heat sealing conditions: temperature 140 ° C., pressure 1 Kg / cm ² , time 1 second. Heat seal strength: Kg / 15mm width. Anti-fogging effect: Pour warm water of 40 ℃ into a 300cc beaker, cover the upper part with a sample film, seal and store in a constant temperature room of 5 ℃, and store it in a thermostatic chamber at 5 ℃. Visually judge the haze after 5 hours. It's wet. After that, the antifogging effect gradually deteriorates, and 1: minute water drops adhere to the film and the inside cannot be seen.

[0023]

As shown in Table 1, the present invention has sufficient antifogging property because it contains an ionic surfactant, and since it does not inhibit adhesion, it also has heat seal strength.
It is very effective as a transparent packaging material that needs to show its contents in over-the-counter sales of foods that have a lot of water and tend to cause condensation.

[0024]

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a film for anti-fog packaging material according to the present invention.

FIG. 2 is a conventional anti-fog polyolefin 6a.
FIG. 3 is a schematic cross-sectional view of a film for anti-fog packaging material according to the configuration of the present invention including

FIG. 3 is a schematic cross-sectional view of a film for anti-fog packaging material in which the anti-fog polyolefin 6 according to the present invention is formed by a conventional technique.

FIG. 4 is a schematic cross-sectional view of a film for anti-fog packaging material according to the related art.

[Explanation of symbols]

1. Support substrate 2. Ink layer 3. Anchor coat agent layer 4. 4. Polyolefin layer for adhesion 5. Intermediate barrier layer 6. Antifogging Polyolefin Layer Containing Ionic Surfactant 6a. Antifog Polyolefin Layer Containing Nonionic Surfactant

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B65D 65/40 A 9028-3E

Claims (2)

[Claims] 1. An intermediate barrier layer of an antifogging agent is provided between a backing-printed supporting substrate (1) film and an antifogging polyolefin film (6) containing an ionic surfactant.
A film for anti-fog packaging material, which is a composite of (5). 2. The anti-fog package according to claim 1, wherein the intermediate barrier layer (5) contained in the film has an oxygen permeability of 100 cc / m ² · 24 hrs., A haze of 25% or less, and a polyolefin layer on both sides. Film for material.