JP2001247114A - Laminate and multilayered container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for use as a packaging material which has heat resistance allowing cooking in a microwave oven and gas barrier properties for improving preservability and which is excellent in deep drawing properties. SOLUTION: The laminate comprises a synthetic resin sheet comprising at least five layers including an olefin based resin layer (A), an adhesive resin layer (B), an oxygen gas barrier resin layer (C), an ethylene based terpolymer resin layer (D) and a foamed polypropylene sheet (E) with a relation of ratios in layer thicknesses of a >=b+c+d when a ratio of the layer (A) is a%, a ratio of the layer (B) is b%, a ratio of the layer (C) is c% and a ratio of the layer (D) is d%. Further, a thickness of the layer (B) is 3 μ or more, a thickness of the layer (C) is 5 μm or more, and a thickness of the layer (D) is 5 μm or more, while bonding strength between the layer (D) and the sheet (E) is 150 g/15 mm width or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin sheet laminate which can be suitably used mainly as a packaging material for food packaging.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of resource saving and environmental consideration,
There is a strong demand for reducing the volume of synthetic resin products, particularly packaging products that use a large amount of the plastic resin products. In addition, recently, individualized diets due to changes in eating habits have progressed, and the spread of cooked or semi-cooked foods has been remarkable, and a simple cooking method using a microwave oven has been demanded, and packaging containers are used directly as tableware. Things are no longer rare. Along with this,
Demands for heat resistance and preservation of packaging containers are increasing. In general, cooked foods are packaged in synthetic resin film, and when heated in a microwave oven, the film used for packaging is not heat-resistant, so it is necessary to temporarily transfer them to pottery or glass containers. After cooking, the temperature of the container was high, and it was necessary to handle it with care. Also,
A container using a foam sheet considering only heat resistance has a low oxygen gas barrier property and cannot be stored for a long time. For this reason, a container in which a multilayer sheet of a foam sheet and a barrier material is molded is used. However, since the adhesive strength between the foam sheet and the barrier material is low, the drawing depth during molding is limited, and a complicated container shape is required. Is difficult. Furthermore, when the container filled with the contents and the lid-sealed container is heated and cooked in a microwave oven, and the lid is opened, there is a risk that the container-forming film peels off the foam sheet together with the lid and spills the contents.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-resistant material capable of microwave cooking and a gas barrier property for enhancing the preservability of cooked or semi-cooked contents. An object of the present invention is to provide a laminate for packaging materials having excellent drawability.

[0004]

The present invention provides an olefin resin layer (A), an adhesive resin layer (B), an oxygen gas barrier resin layer (C), and an ethylene terpolymer resin layer (D). ,
In the synthetic resin sheet composed of at least five layers of the expanded polypropylene sheet (E), the thickness ratio of each layer is a% for the olefin resin layer (A) and b for the adhesive resin layer (B).
%, The oxygen gas barrier resin layer (C) is c%, and the ethylene-based terpolymer resin layer (D) is d%.
+ C + d, the adhesive resin layer (B) has a thickness of 3 μm or more, the oxygen gas barrier resin layer (C) has a thickness of 5 μm or more, and the ethylene-based terpolymer resin layer (D)
And the adhesive strength between the ethylene-based terpolymer resin layer (D) and the expanded polypropylene sheet (E) is 150 g / 15 mm width (180 ° peeling, peeling speed 300 mm / min) or more. It is a laminate. Preferred embodiments include an olefin resin layer (A), an adhesive resin layer (B), an oxygen gas barrier resin layer (C), an ethylene terpolymer resin layer (D), and a foamed polypropylene sheet (E). Is a laminate obtained by laminating at least five layers of a synthetic resin sheet having at least five layers in the order of A / B / C / D / E. The present invention is also a multilayer container in which the laminate is shaped with the foamed polypropylene sheet (E) as an outer layer side.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The olefin resin used in the present invention is not particularly limited, but a polypropylene resin can be suitably used from the viewpoint of heat resistance. More preferably,
Melt index is 0.1 to 5g / 10min (JI
SK6758), and 3 to 20 parts by weight of a low-density polyethylene resin or a high-density polyethylene resin may be blended in consideration of moldability.
Further, for the purpose of further improving heat resistance, it is possible to appropriately blend a 4-polymethylpentene-1 resin or a homopolymer type cyclic polyolefin resin, which is an olefin-based resin and relatively excellent in heat resistance. Also,
As the polypropylene resin, a homopolypropylene resin can be preferably used, but a copolymer with various ethylene resins or a rubber component or a thermoplastic elastomer for the purpose of improving impact resistance may be blended.

The adhesive resin used in the present invention includes:
There is no particular limitation as long as the olefin resin layer (A) and the oxygen gas barrier resin layer (C) are bonded to each other.
For example, a resin obtained by modifying an olefin resin with maleic anhydride or the like and grafting it to impart adhesiveness can be suitably used. Further, an ethylene terpolymer resin used for the layer (D) of the present invention may be used. The thickness of the adhesive resin layer (B) needs to be 3 μm or more. If it is less than 3 μm, good adhesive strength cannot be obtained between the olefin resin layer (A) and the oxygen gas barrier resin layer (C).

The oxygen gas barrier resin used in the present invention has an oxygen permeability coefficient of 20 cc · 100 μm / m ² · atm.
Day (23 ° C., 65% RH) or less. For example, ethylene-vinyl alcohol copolymer,
Nylon MXD6, polyvinylidene chloride, nylon 6,
Gas barrier resins such as nylon 6,6, amorphous polyamide, polyester and the like. The ethylene-vinyl alcohol copolymer is not particularly limited, but a commercially available ethylene copolymer having an ethylene copolymerization ratio of 20 to 50 mol% can be suitably used. Nylon MXD6 is a polyamide resin obtained by a polycondensation reaction between metaxylylenediamine and adipic acid, and its production method is not particularly limited. In addition to metaxylylenediamine and adipic acid, a hydrochloride of metaxylylenediamine is used. And various derivatives such as halides and esters of adipic acid as starting materials. Also, 90 units of diamine unit
It is also possible to use only a polyamide in which at least mol% is a meta-xylylenediamine unit, or a mixed resin of a polyamide in which at least 90 mol% of a diamine unit is a meta-xylylene diamine unit with another thermoplastic resin. For example,
An amorphous polyamide can be mixed for the purpose of improving the moldability. Amorphous polyamide is also called amorphous nylon or transparent nylon, and unlike linear aliphatic nylon such as nylon 6, nylon 6,6, little or no crystallization of the polymer occurs. It is a special nylon with very low speed. Examples of the amorphous polyamide used in the present invention include polycondensates of terephthalic acid and trimethylhexamethylenediamine, 2,2
A copolymer of bis (p-aminocyclohexyl) propane with adipic acid and azelaic acid, a copolycondensate of bis (3-methyl-4-aminocyclohexyl) methane with isophthalic acid and ω-aminododecanoic acid, Examples include a cocondensate of diphenylmethane diisocyanate with a mixture of adipic acid, azelaic acid and isophthalic acid, and a copolycondensate of terephthalic acid and isophthalic acid with hexamethylenediamine. Furthermore, a diamine or dicarboxylic acid other than metaxylylenediamine and adipic acid can be copolymerized with a polyamide in which 90% or more of the diamine units are metaxylylenediamine units. The thickness of the oxygen gas barrier resin layer (C) is 5
It must be at least μm. If it is less than 5 μm, good gas barrier properties cannot be obtained.

The ethylene terpolymer used in the present invention is not particularly limited, but is preferably a polymer of ethylene and a monomer having a carbonyl group. In particular, an ethylene-acrylate-maleic anhydride terpolymer resin can be suitably used because of its good thermal stability and low odor. In addition, other thermoplastic resins such as polyethylene and polypropylene may be mixed as long as the adhesive strength of the ethylene-based terpolymer resin is not impaired. The thickness of the ethylene-based terpolymer resin layer (D) needs to be 5 μm or more.
If the thickness is less than 5 μm, the adhesive strength with the foamed polypropylene sheet becomes weak, and the width is 150 g / 15 mm (180 °).
There is a possibility that a strength of peeling or peeling speed of 300 mm / min or more cannot be obtained. In this case, delamination easily occurs between the D and E layers when the sealed package is opened.

In the laminate of the present invention, each of the olefin resin layer (A), the adhesive resin layer (B), the oxygen gas barrier resin layer (C), and the ethylene terpolymer resin layer (D). The layer thickness ratio is a% for the olefin-based resin layer (A), b% for the adhesive resin layer (B), c% for the oxygen gas barrier resin layer (C), and the ethylene-based terpolymer resin layer (D). Is d%, it is necessary that a ≧ b + c + d. If a <b + c + d, the thickness tends to vary during molding.

The laminate used in the present invention is composed of an olefin resin layer (A), an adhesive resin layer (B), an oxygen gas barrier resin layer (C), and an ethylene terpolymer resin layer (C). D) a synthetic resin sheet comprising at least five layers of a foamed polypropylene sheet (E), wherein at least A / B / C
It is preferable to laminate five or more layers in the order of / D / E. If necessary, for example, A / B / C / B / D / E, A
/ D / B / C / B / D / E, A / B / C / B / A / D /
E, the layer configuration may be increased as in A / B / C / B / A / B / C / D / E. If necessary, the ethylene-based terpolymer resin layer (D) may be used as an adhesive resin between the A / C layers. Although the thickness of the laminate of the present invention is not necessarily limited, it is preferably 100 to 1 in consideration of moldability and product cost.
000 μm. The method for producing a laminate of the present invention can be obtained by coextrusion, lamination, or the like using the above-described resin. As a laminating method, a known method such as extrusion lamination, dry lamination, or thermal lamination can be used.

[0011]

Example: Multi-layer multi-manifold co-extrusion die
A co-extruded film having a layer thickness shown in Table 1 and a total thickness of 100 μm was produced using the following raw materials. Next, this film and a foamed polypropylene sheet (thickness 500 μm)
and m) were laminated by a thermal lamination method to obtain a laminate. The lid material is PVDC-coated stretched nylon film (thickness 25μm) and 200g per 15mm width
PP film that can be easily opened with a strength of 50mm (thickness 50μm)
Was dry-laminated. The obtained laminate was evaluated for formability using a continuous deep drawing packaging machine, filled with a cooked hamburger, and sealed with a lid to obtain a sealed package. After reheating the sealed package in a microwave oven, the lid material was peeled off, and the adhesion was evaluated.

The raw materials used are as follows. (A) Olefin-based resin: Polypropylene (PP1) “Sumitomo Chemical Industries, Ltd., Sumitomo Noblen FH1016” Polypropylene (PP2) “Nippon Polychem Co., Ltd., Novatec PP FY4” (B) Adhesive resin: “Mitsui Chemicals, Inc. ) ADMER QB55
0 "(C) Oxygen gas barrier resin: Ethylene-vinyl alcohol copolymer (EVOH)" Kuraray Co., Ltd., Eval F101AZ "(oxygen permeability coefficient 0.
4cc ・ 100μm / m ²・ atm ・ day) MXNY “Mitsubishi Gas Chemical Co., Ltd., MX nylon, MXD
6 "(oxygen permeability coefficient 1 cc · 100 µm / m ² · atm
-Day) (D) Ethylene-based terpolymer resin: ethylene-acrylate-maleic anhydride terpolymer "Nippon Polyolefin Co., Ltd., Lexpearl ET182" The layer constitution and thickness are as shown in Table 1. It is. The value in parentheses in the table is the thickness (μm).

The evaluation was performed by the following method. (1) Formability ---- The laminate is 100φ30mm at 100 ° C
It was molded to a depth and the state was observed. ：: good, ×: uneven thickness, delamination occurred (2) Heat resistance ---- The state of the sealed package when heated for 3 minutes in a microwave oven was confirmed. ：: good, ×: deformation, delamination occurred (3) Adhesion ---- The state of the sealed package at the time of opening was confirmed. ：: good, ×: delamination occurred (4) Oxygen gas barrier property --- Oxygen permeability coefficient (cc / m ² · atm · d) of the co-extruded film by the OXTRAN method
ay) was measured. Table 2 shows the evaluation results.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

According to the laminate of the present invention, a container excellent in moldability, oxygen gas barrier properties and heat resistance and suitable for a food package heated by a microwave oven can be obtained.

 ────────────────────────────────────────────────── ─── Continued on the front page F-term (reference) 3E033 AA20 BA16 BA21 BB08 CA07 CA16 FA10 3E086 AD06 BA04 BA15 BB31 BB41 CA01 4F100 AK03A AK04J AK07D AK16 AK24J AK25J AK48 AK62C AK69 AL01C BA04 BA07B10E03 BA10 BA10 BA03 BA10 AA02P AK32R AL02Q AL03Q CA05 JA58

Claims (3)

[Claims] 1. An olefin resin layer (A), an adhesive resin layer (B), an oxygen gas barrier resin layer (C), an ethylene terpolymer resin layer (D), and a foamed polypropylene sheet (E). In a synthetic resin sheet comprising at least five layers, the layer thickness ratio is a% for the olefin resin layer (A), b% for the adhesive resin layer (B), c% for the oxygen gas barrier resin layer (C), and ethylene-based. Assuming that the terpolymer resin layer (D) is d%, a ≧ b + c + d, and the adhesive resin layer (B) has a thickness of 3 μm or more and the oxygen gas barrier resin layer (C) has a thickness of 3 μm or more. A thickness of 5 μm or more, and a thickness of the ethylene-based terpolymer resin layer (D) of 5 μm or more;
A laminate having an adhesive strength between the ethylene-based terpolymer resin layer (D) and the expanded polypropylene sheet (E) of 150 g / 15 mm width (180 ° peeling, peeling speed 300 mm / min) or more. 2. An olefin resin layer (A), an adhesive resin layer (B), an oxygen gas barrier resin layer (C), an ethylene terpolymer resin layer (D), and a foamed polypropylene sheet (E). A synthetic resin sheet comprising at least five layers
The laminate according to claim 1, wherein at least five layers are laminated in the order of / B / C / D / E. 3. A multilayer container in which the laminate according to claim 1 or 2 is shaped with the foamed polypropylene sheet (E) as an outer layer side.