JPS63267543A - Base material for laminate - Google Patents

Abstract

PURPOSE:To obtain a base material for laminate, which has excellent adhesion between a resin layer and a metal deposit and low temperature heat-sealing properties and strong stiffness, by a structure wherein the metal deposit is laminated to a specified graft modified resin layer. CONSTITUTION:Graft modified resin is obtained by grafting unsaturated carboxylic acid or its anhydride to polypropylene resin and/or polyethylene resin having the density of 0.93g/cm<3> or higher in the presence of radical generator. The resultant resin is turned into a resin film with a T-die casting or inflation method so as to vapor-deposit metal onto the surface of the film under the normal vacuum spraying conditions in order to laminate a metal deposit II to the graft modified resin layer I. If the density of the polyethylene resin is below 0.93g/cm<3>, the resultant base material has weak stiffness so that a packaging material, which is produced by laminating said base material for packaging snack food, lacks tension, resulting in lowering commercial value in appearance. As the deposited metal, Al, Zn, Ag, Cu, Cd and the like are cited.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to substrates for lamination.

More specifically, the present invention relates to a laminating base material having a metal vapor deposited layer.

[Conventional technology] For the purpose of improving gas barrier properties, appearance, and aesthetics,
BACKGROUND ART In recent years, plastic films whose surfaces have been subjected to metal vapor deposition have been widely used as base materials for laminations such as extrusion laminates and dry laminates.

In particular, aluminum-deposited cast polypropylene (hereinafter referred to as VMCPP) film has excellent low-temperature heat-sealing properties and is strong, so it is widely used as a base material for packaging snack foods such as potato chips, popcorn, and rice crackers. ing.

VMCPP film is usually coated with aluminum after corona treatment, but even after corona treatment, the adhesion between cast polypropylene (hereinafter abbreviated as CPP) film and vapor deposited aluminum is weak, so VMCPP film and biaxially oriented Polypropylene (hereinafter abbreviated as OPP), nylon,
Even if a resin with excellent adhesion to metal is used for sand lamination with a film base material such as polyester, the resulting laminate will easily suffer from delamination between the aluminum vapor-deposited layer and the CPP film layer. There was a problem that happened.

C to increase the adhesion between vapor-deposited aluminum and CPP film.
It is being considered to apply an anchor coating agent to a PP film and then perform aluminum vapor deposition. However, with this method, the CPP film tends to undergo heat shrinkage when the anchor coating agent dries, and as a result, uniform aluminum deposition is not achieved, which not only improves aesthetics, but also reduces product yield and increases costs. .

[Problems to be Solved by the Invention] An object of the present invention is to provide a base material for lamination that has excellent adhesive strength with a metal vapor-deposited layer, low-temperature heat sealability, and is strong.

[Means for solving the problems] The gist of the present invention is that polypropylene resin and/or
．． Regarding a base material for lamination, characterized in that a vapor-deposited metal layer (II) is laminated on a graft-modified resin layer (1) obtained by graft-reacting an unsaturated carboxylic acid or its acid anhydride to a polyethylene resin of 93 g/m or more It is.

The graft-modified resin constituting layer (I) of the present invention is an unsaturated carboxylic acid or its acid anhydride added to a polypropylene resin and/or a polyethylene resin with a density of 0.93 g/cI1 or more in the presence of a radical generator. It is obtained by grafting reaction.

Among the resins constituting the layer (1) of the present invention, the polypropylene resin is not particularly limited in its type, and may include polypropylene resins used in ordinary extrusion molding, propylene resins, etc.
Ethylene random or block copolymer resins are preferably used.

Further, it is essential that the polyethylene resin has a density of 0.93 g/i or more according to JIS K-6780. If the density is less than 0.93 g/cd, the stiffness when used as a base material is weak,
When a product laminated using the base material of the present invention is used as a packaging material for snack foods, etc., the packaging material lacks "tightness", so there is a risk that the product value in appearance may be reduced.

Examples of the unsaturated carboxylic acid or its acid anhydride used in the present invention include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, etc. is exemplified.

In the method of grafting these onto polymer resins such as polyethylene and polypropylene described above in the present invention, an unsaturated carboxylic acid or its acid anhydride of 0.1 to 100% by weight based on the polymer resin and the polymer resin is used. is dissolved in a suitable solvent such as toluene or xylene, and an organic peroxide such as benzoyl peroxide, lauryl peroxide, or dicumyl peroxide or a radical initiator such as azobisisobutyronitrile is added to this solution. This is achieved by heating at a temperature higher than the decomposition temperature of the radical initiator, usually 50 to 300°C, for 1 minute to 10 hours. The graft reaction can also be carried out by directly adding a radical initiator to a molten polymer resin and kneading the mixture at a temperature above the melting temperature of the polymer resin for 1 minute to 10 hours. There is no particular restriction on the grafting rate at this time, but it is generally preferably in the range of about 0.1-15% by weight.

The melt flow rate (MPR) of the resin constituting the layer (I) of the present invention is 0.1 to 1Q from the viewpoint of extrusion processability.
Og/10 minutes is preferred.

Examples of the vapor-deposited metal constituting the layer (II) of the present invention include AI% ZnSAg, Cu, and Cd.

The method of vapor depositing the layer (II) on the layer (1) is not particularly limited, and can be carried out by employing normal vacuum vapor deposition conditions on the surface of a resin film obtained by T-die casting or inflation.

The thickness of the layer (I) of the present invention is not particularly limited, but in consideration of the stiffness and economic efficiency of the laminate base material, the thickness of the layer (1) is suitably 10 to 100 μl. Further, the thickness of the layer (II) is about 2 to 100 a+μ if normal vacuum deposition conditions are employed.

<X> For the purpose of imparting slip properties during extrusion processing of the resin constituting the layer and preventing blocking of the film after extrusion processing, 1) saturated or unsaturated fatty acid amide, fatty acid It is preferred to use about 0.01 to 5% by weight of one or more metal salts, saturated or unsaturated fatty acid bisamides, and inorganic fillers based on the resin.

[Example] Next, the present invention will be explained in more detail with reference to Examples.

Examples 1-2 Comparative Examples 1-2 A low density polyethylene resin (MFR - 7 g/10 min, density - 0,939 g/d) was melt mixed with maleic anhydride in the presence of a dicumyl peroxide radical initiator, A maleic anhydride-modified resin obtained by graft copolymerizing 0.5% by weight of maleic anhydride was obtained (referred to as A).

Polypropylene resin (MPR-10g/lo min, density-
0,907 g/d) with maleic anhydride in the presence of a dicumyl peroxide radical initiator;
Maleic anhydride-modified resins were obtained by graft copolymerizing 0.3% by weight of maleic anhydride (referred to as B). These modified resins were used as the resin for layer (I).

The resin shown in Table 1 was extruded using a T-die extruder at the temperature and thickness shown in Table 1 to obtain a cast film of layer (1). 1O-4u+lI on this cast film
Aluminum was vacuum-deposited at a vacuum degree of g to produce a base material for lamination.

With this base material on the sand side and the OPP with a thickness of 20 μm on the main feeding side, an anchor coating agent (Toyo Morton Co., Ltd. splitting product name "Atocoat 37FIJ") was used to apply an anchor coat to the OPP, and then ethylene-acrylic acid copolymer resin (M
Sand lamination was carried out using FR-20g (acrylic acid content: 9 vt%) for 710 minutes at a resin temperature of 210° C. and a thickness of 20 μm.

The adhesive strength between the ethylene-acrylic acid copolymer resin film and the aluminum-deposited plastic film of the resulting packaging material was measured.

Furthermore, the (I) layers were heat-sealed using the obtained packaging material to evaluate low-temperature heat-sealability.

Furthermore, bags containing items were made using the obtained packaging material and their appearance was examined. The results are shown in Table 1. For comparison, VMCPP (
Table 1 and Comparative Example 2 also show the evaluation results of packaging materials obtained by sand-laminating CPP (corona treatment) and OPP with ethylene-acrylic acid copolymer resin.

As shown in Table 1, the packaging material laminated using the base material of the present invention has excellent adhesion to aluminum vapor deposition, low-temperature heat-sealability, and is strong, so the appearance of the bag is good.

Table-1 The symbols in Table 1 have the following meanings.

PE: polyethylene resin MPR-3g710 minutes Density - 0,925g/cd PP: Polypropylene resin' MPR-10g/10min Density - 0,907g/cd The test methods are as follows.

! ) Adhesive strength The adhesive strength between the ethylene-acrylic acid copolymer resin of the packaging material after lamination and the vapor-deposited film was measured using a Schizpper type tensile tester at a peeling rate of 300+a+s/m1n. In all samples, peeling occurred between the (1) layer and (■) layer.

2) Low temperature heat sealability Heat seal the (1) layers of the packaging material after lamination with a heat sealer at 180℃, 1kg/cj, 1 second, and peel off the sealed part by hand to ensure good adhesion. It was marked as ○, and if it was not adhered, it was marked as ×.

3) A 15×20ao bag filled with 40g of potato chips using the laminated packaging material was heated to 160°C, 1 kg/cj,
It was produced by heat sealing for 1 second.

The produced bags were observed, and those with good appearance were rated ○, and those with poor appearance due to lack of elasticity were rated ×.

[Effects of the Invention] The base material of the present invention has excellent adhesive strength between vapor-deposited metal and resin film, has good low-temperature heat sealability, and is strong, so it can be used for extrusion lamination, hot melt lamination, dry lamination, etc. After lamination, it is suitable for use as a packaging material for snack foods such as potato chips, popcorn, and rice crackers.

Claims (1)

[Claims] 1) Polypropylene resin and/or density 0.93g/c
A base material for lamination, characterized in that a vapor-deposited metal layer (II) is laminated on a layer (I) made of a graft-modified resin obtained by grafting an unsaturated carboxylic acid or its acid anhydride to a polyethylene resin having a molecular weight of m^3 or more. .