JPS6061252A - Laminated sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transparent laminated sheet that is transparent and has excellent hygiene and barrier properties.

BACKGROUND ART Conventionally, in order to take advantage of the characteristics of various materials, research has been actively conducted on composites of different materials to form a laminate to meet various required physical properties. In particular, there are strict requirements for food packaging materials, such as hygiene, moisture resistance, gas barrier properties, UV barrier properties, water resistance, and chemical resistance.

Oil resistance, cold resistance, heat resistance, thermal adhesion, transparency, flavor retention, strength, cost, flexibility, etc.

Various functions are required depending on the purpose.

Since it is difficult to satisfy these various requirements with a single material, it has become common to use a stack of various materials in food packaging materials. These f
Methods for obtaining a V-layer fan are broadly divided into methods using adhesives and methods without using adhesives such as heat seal lamination, extrusion lamination, etc.

Although the latter method is industrially useful, the former method currently predominates due to restrictions on the combination of materials.

Conventionally, polyurethane adhesives have been used in food packaging laminates. Although polyurethane adhesives exhibit excellent adhesion performance, there remain problems such as the possibility of migration of low molecular weight compounds into foods and the need for an aging period after adhesion. For this reason, modified polyolefin resins containing carboxyl groups are now being used in place of polyurethane adhesives. This modified polyolefin resin itself is a useful material because it has few hygiene problems and has good adhesion to polyolefin resins, aluminum foil, and the like. However, these modified polyolefin resins include polyethylene terephthalate (PET), polyvinylidene chloride, which is commonly used as a material for food packaging laminates,
Poor adhesion to poval, nylon, ethylene/vinyl acetate copolymer hydrolysates, etc.

There still remains the problem that there are restrictions on the combination of materials, and there is also the problem that when laminated sheets using aluminum foil are used for packaging purposes, the contents cannot be seen.

As a result of intensive research in view of the above-mentioned current situation, the inventors of the present invention have developed an aluminum or tin thin film with a thickness of 100λ or less.
- polyethylene terephthalate (
It has been found that it is possible to obtain a laminate with sufficient adhesive strength for practical use by thermocompression bonding of a plastic base material such as PET) and a carboxyl group-containing polyolefin without using a polyurethane adhesive. It cannot be said to have sufficient barrier properties against permeation of gases such as moisture and oxygen gas, which is important when used as a packaging film.
For applications that require oxygen barrier properties, polyvinyl alcohol, hydrolyzate of ethylene/vinyl acetate copolymer, etc. are usually used, and for applications that require moisture barrier properties, polyvinylidene chloride is used. It was necessary to laminate the .

However, creating such a multilayer laminated sheet is disadvantageous in terms of cost, and also makes the processing process complicated from an industrial perspective.Depending on the type of barrier film selected, adhesives may have to be used. Most of them cannot be laminated, which contradicts the original purpose of improving hygiene.

In view of the above-mentioned current situation, the inventors of the present invention sought to improve transparency.

As a result of extensive research in order to obtain a composite film with excellent barrier properties and hygiene properties, we have found that - By using a thin layer formed by vapor-depositing or sputtering silicon oxide as one layer of the composite film, we have created a transparent laminated sheet with excellent performance. invention that can be obtained (patent application 1732-1982)
No. 95) was completed, but the present invention was developed as a result of further research.
This is based on the knowledge that similar effects can be obtained with oxides other than silicon oxide. In other words, the present invention provides a plastic sheet (A), an oxide film formed by vapor deposition or sputtering of one or more selected from silicon, titanium, aluminum, or their oxides (excluding silicon oxide). thing 117)
tf (B) is a transparent laminate sheet consisting of at least four layers including a thin layer (C) formed by vapor deposition or sputtering of metal and a polyolefin layer (D) containing a carboxyl group-containing polyolefin, and the polyolefin layer (1)) This relates to a sheet characterized in that it is laminated with a thin Ju (C) layer interposed therebetween.

In the present invention, the plastic sheet (A) is
Polyester, especially PET, nylon, polyvinylidene chloride, polyvinyl chloride, poval, hydrolyzate of ethylene/vinyl acetate copolymer, polystyrene, polycarbonate, polystyrene, polyolefin, modified polyolefin, cellophane, urethane resin, acrylic 414
There are films such as Jll, and these films can be uniaxially or biaxially stretched depending on the purpose. The surface of these films may be untreated, but for the purpose of further improving the adhesive strength, the surface of these films may be subjected to physical treatment such as sandblasting (I! warm plasma treatment, corona discharge treatment, or coating of BRIMAR). It may also be one that has been subjected to chemical or chemical treatment.

In the present invention, the oxide thin layer (B) obtained by vapor deposition or sputtering is itself transparent.

As shown in Table 1, a film thickness of approximately 200 mm provides sufficient oxygen gas barrier properties, and a film thickness of approximately 600 mm exhibits barrier properties equivalent to that of a high retort. The method of forming these oxide thin layers (B) by vapor deposition or sputtering is known per se.

The respective oxide thin layers (B) can also be formed by electron beam evaporation, radio frequency sputtering, or reactive sputtering of silicon dititanium and aluminum using oxygen gas.

The thin metal layer (C) is also formed by vapor deposition or sputtering, which is known per se. Metals include aluminum, 61. Examples include steel, magnesium, zinc, 2.7 Kel, titanium, iron, zirconium, and alloys containing these as main components, but aluminum, magnesium, tin, and the like are preferable from the viewpoint of hygiene and cost. Thin metal layer (
The thickness of C) is from a monomolecular layer to 100 layers, preferably from several layers to about 30 layers from the viewpoint of transparency and adhesiveness. If there are more than 100 people, transparency will be compromised.

In the present invention, carboxyl group-containing polyolefin (
Hereinafter referred to as modified polyolefin. )as.

Olefinic monomers such as ethylene, propylene, butene, and acrylic acid, methacrylic acid, and itaconic acid.

α such as fumaric acid, maleic acid, and maleic anhydride.

Copolymerization or graft polymerization of β-unsaturated carboxylic acids or their anhydrides, polyolefins graft-polymerized or graft-polymerized with α, ρ-unsaturated carboxylic acids, etc., or metal compounds added to these materials. was blended. What is generally called an ionomer can also be used, and these can be used alone or in combination with an unmodified polyolefin. From the viewpoint of adhesive strength, the carboxyl group-containing unsaturated monomer is 0.01
More than heavy sweetness, preferably 0. (The range is 15 to 10% by weight.

A specific method for manufacturing the laminated 1B sheet related to item 1 is to form a thin oxide layer (B) formed by vapor deposition or sputtering on the plastic sheet (A), and then add the plastic sheet (A) and /or a metal thin layer (C) is deposited on the oxide thin layer (B), < is formed by sputtering, and this metal layer ((
The modified polyolefin layer (D) is laminated on the extruder 2I, or the modified polyolefin layer (D) is laminated on the
There is a method in which Polio L/Fin is used as a film and laminated by thermocompression bonding. When used as a film, its surface can be treated with corona discharge treatment or the like to improve adhesiveness.

Specifically, the laminated sheet according to the present invention includes PET/thin oxide layer (B)/thin metal layer (C)/modified polyolefin (D)/(polyolefin), nylon/thin oxide J
Ej (B) / thin metal layer (C) / modified polyolefin (D) / (polyolefin), stretched polypropylene / thin oxide layer (B) / thin metal layer (C) / modified polyolefin (D) / (polyolefin), Oxide thin layer (B)/P
E'T/Thin metal layer (C)/Modified polyolefin (D)/
(Polyolefin), oxide thin layer (B)/nylon/
Metal thin 7G (C) / modified polyolefin (D) /
(Polyolefin) 9M Compound layer (B)/stretched polypropylene/thin oxide layer (B)/thin metal layer (C)/modified polyolefin (D) can be exemplified.

The above-mentioned (polyolefin) means that a polyolefin layer can also be formed.

Although it is preferable to use the laminated sheet according to the present invention by taking advantage of its transparency, in some cases it may be required to have so-called stiffness as a packaging material, and transparency may be sacrificed. However, it can also be used by laminating δ)L or synthetic paper, or it can also be used by laminating other materials depending on the purpose.

In addition, conventional films such as saponified ethylene-vinyl acetate copolymer and POVAL, which are excellent when used with oxygen gas, have a drawback of high moisture permeability. In this point, before oxide +
By providing d(B), the transmission Δ11 river is significantly changed i!
For example, 'PET/adhesive (e.g. polyurethane adhesive)/thin oxide layer (B)/saponified ethylene-vinyl acetate copolymer film/thin metal layer (C)/modified polyolefin (D)/polyolefin If it is structured as a film, a laminated sheet with satisfactory gas barrier properties and moisture permeability can be obtained.

The present invention will be explained in more detail below using Examples and Comparative Examples.

In an example, titanium was reactively sputtered on one side of an axially stretched PET film (east side +1 m M, trade name Lumirror PI 1. I 211) in a mixed gas of oxygen gas and argon gas, and the thicknesses shown in Table 1 were obtained. On the aluminum-deposited surface of the base material, a titanium oxide layer was formed, and then aluminum was vacuum-deposited to a thickness of approximately 20 mm.

Modified polypropylene (maleic acid modified polypropylene,
Manufactured by Toyo Ink Mfg.A., product name: Liocent 1063-
4) was formed into a film (40 μm) by a conventional method, and then pressure-bonded at 200° C. and a linear pressure of 5 Kg/cm to obtain a @layer sheet. The adhesive strength of this laminated sheet was measured using the T-peel method and was 1.5 kg/15 mm or more.
The results of measuring the elementary gas permeability and water vapor permeability are as shown in Table 1.

Further, the adhesive strength of this composite film after a retort test at 121° C. for 30 minutes was 800 g/15 mm.

It was sufficiently practical.

Margin Table 1 (Note 1) Measured using the isobaric method, units are ml/n724 hours.
It is 1 atm and 25°C.

(Note 2), +1SZ 0208 Measured by cup method (40"C, RH90%), unit is g/I・24 hours.

(llE3)Nl) indicates not detected.

Comparative Example 1 The laminated sheet obtained by omitting the aluminum vapor deposition in Example 1 had almost no adhesive strength and was easily peeled off.

Example 2 In Example 1, the PET film was replaced with a nylon film (manufactured by Unitika Qi, trade name: Emblem).

The adhesive strength of a laminated sheet obtained in the same manner by sputtering titanium oxide to a thickness of approximately 600 μm using 15μ) and using tin instead of aluminum was 1.5K.
g/15 mm or more, oxygen gas permeability is 1.1 ml
/-・24 hours・1 atmosphere・25°C.

Example 3 500 layers of aluminum oxide are deposited on a biaxially stretched PET film (same as Example 1), a thin layer of approximately 10 layers of aluminum is applied thereon by vacuum evaporation, and an ionomer resin is applied on top of it. (Himilan, a product name manufactured by Mitsui Polychemical Co., Ltd.) is extruded to a thickness of approximately 30μ.
The adhesive strength obtained by Chiron lamination is 1.0 Kg.
/ 15 mm, and the oxygen gas permeability is 15n+l/
ITr, 24 hours, 1 atm, 25℃, moisture permeability 0.1g
/-・24 hours.

Example 4 When a mixture of the same amount of aluminum and tin was vapor-deposited in place of ζ aluminum in Example 1, the adhesive strength, oxygen gas permeability, and moisture permeability of the laminated sheets obtained in the same manner were almost the same.

Example 5 Sputter silicon dioxide to a thickness of 600 nm on one side of a Ti1 Sun film (same as Example 2).

On the other side, aluminum was vacuum deposited to a thickness of 20 mm.

A modified polypropylene film was pressure-bonded to this aluminum vapor-deposited surface in the same manner as in Example 1 to obtain a laminated sheet. The adhesive strength of this laminated sheet is 1.5 Kg/l 5 m
n+, and the oxygen gas permeability is 1.2 ml/rd・
After the same retort test as in Example 1 for 24 hours at 1 atm and 25° C., no deterioration in adhesive strength was observed.

Example 6 A biaxially stretched PET film (same as in Example 1) and a saponified ethylene-vinyl acetate copolymer film (15μ) were laminated with a urethane adhesive to form an ethylene-f'[saponified vinyl copolymer film]. under argon gas,
Example 1 After sputtering titanium dioxide to each thickness shown in Table 2 and vacuum evaporating the thickness to a thickness of 20 mm,
A modified polypropylene film was pressed in the same manner as above to obtain a laminated sheet.

The adhesive strength of this ayz sheet is 1.5 Kg715 m
m or more, and the oxygen gas permeability is approximately l ml/rd
- 24 hours, 1 atm, 25°C or less, and moisture permeability was as shown in Table 2.

Table 2 patent applicant Toyo Ink Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. Plastic sheet (A), formed by vapor deposition or sputtering of one or more selected from silicon, titanium, aluminum, or their oxides (excluding silicon oxide); It is a transparent laminated sheet consisting of at least four layers, including a thin oxide layer (B), a viaha<c) formed by vapor deposition or sputtering of a metal, and a polyolefin layer (D) containing a carboxyl group-containing polyolefin. (D) is a sheet that is laminated with a thin layer (C) interposed therebetween. 2. Plastic sheet (A)/Thin oxide layer (B)/I
The sheet according to claim 1, wherein the sheet has a structure of it1wi (C)/polyolefin layer (D). 3. Oxide thin layer (B)/plastic sheet (A)/f
The sheet according to claim 1, comprising a structure of iI layer (C)/polyolefin layer (D). 4. The sheet according to claim 1, wherein the thin layer (C) has a thickness of 100 Å or less. 5. 1 selected from aluminum, magnesium, and tin
The sheet according to any one of claims 1 to 4, characterized in that the sheet is a thin N (C) formed from two or more kinds of metals.