JP2002103542A - Composite film for bottom material of boiling treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite film for a bottom material of boiling treatment which shows high resistance to pin holes and curling properties of a flange part as well as outstanding transparency and luster. SOLUTION: This composite film for a bottom material of boiling treatment is structured of a heat seal resin layer as an innermost layer, a polyamide resin layer as an intermediate layer and a linear chain low density polyethylene resin layer with a thickness of 1-10 μm as an outermost layer and further, and adjacent polypropylene resin layer to the linear chain low density polyethylene resin layer as the outermost layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite film which can be preferably used for deep-drawing packaging of processed foods such as hamburgers and chickens and prepared foods which are boiled after packaging.

[0002]

2. Description of the Related Art Conventionally, in a bottom material having a flange portion obtained by a deep drawing method, in combination with a lid material, a polypropylene resin is used as a film for a high-barrier bottom material in which the flange portion after boiling is not curled. Has been used in the outermost layer. However, since polypropylene resin is very easily crystallized,
There is a problem that gloss and transparency are reduced.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art, and the present invention provides a glossy and transparent film which is free from curling in a flange portion after boiling when combined with a cover material. An object of the present invention is to provide a composite film for a boiled bottom material having good properties.

[0004]

The above object is achieved by the following means.

That is, according to the present invention, the innermost layer is a heat sealing resin layer, the intermediate layer is a polyamide resin layer, and the outermost layer is a linear low density polyethylene resin layer having a thickness of 1 to 10 μm. A composite film characterized in that a polypropylene resin layer is disposed adjacent to a linear low-density polyethylene resin layer, wherein the outermost linear low-density polyethylene resin layer and the polypropylene resin layer are provided. And the total thickness of the adhesive resin layer adjacent to the resin layer is 15 to 40% of the total thickness of the composite film;
The method further comprises disposing a saponified ethylene-vinyl acetate copolymer resin layer on the intermediate layer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, the innermost layer is a heat-sealing resin layer, the intermediate layer is a polyamide resin (hereinafter, referred to as Ny) layer, and the outermost layer is a linear low-density polyethylene resin (hereinafter, Ly).
LDPE. ) And LLDPE of the outermost layer
Adjacent to a polypropylene resin (hereinafter referred to as PP)
It consists of

LLDPE of the outermost layer has a gloss of 120 or more after deep drawing and boil processing (according to JIS K7105)
Are preferred. The α-octene copolymer component is preferred in terms of adhesive strength with the adjacent resin, and the one having a softening temperature of 105 ° C. or higher is desirable in order to prevent fusion of pack products during boiling treatment.

The thickness of the outermost layer LLDPE is 1 to 10 μm
And preferably in the range of 1 to 5 μm. When the thickness exceeds 10 μm, the flange portion after the boil treatment is easily curled, and when the thickness is less than 1 μm, film formation becomes difficult. P between the intermediate Ny layer and the outermost LLDPE layer
It is necessary to provide a P layer.

By providing a PP layer between the Ny layer and the LLDPE layer, there is an effect that curling is less likely to occur in the flange portion after the boiling process.

As the PP, a homopolymer or a random copolymer with ethylene or the like can be used, but it is desirable to use a random copolymer in order to improve the deep drawability. It is preferable to provide an adhesive resin between the PP layer and the Ny layer of the intermediate layer. As the adhesive resin, a usual acid-modified polyolefin resin can be used, and LLDPE /
The total thickness of PP / adhesive resin (hereinafter, referred to as AD) is preferably within a range of 15 to 40% of the total thickness of the composite film.

The thickness of LLDPE / PP / adhesive resin is 40
%, The pinhole resistance deteriorates, and if it is less than 15%, the flange portion after boiling tends to curl, which is not preferable. The thickness of PP is preferably in the range of 20 μm to 50 μm. As Ny of the intermediate layer, 6 nylon, 6-66 nylon, 12 nylon, 6-12 nylon, etc. can be suitably used.

The intermediate layer is provided with a saponified ethylene vinyl acetate copolymer resin (hereinafter referred to as EVO) to impart a barrier property.
H. ) Layer is preferably provided, and is usually provided adjacent to the Ny layer. As the EVOH, those having an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more are preferable from the viewpoint of film forming properties and gas barrier properties.

The innermost heat-sealing resin is low-density polyethylene (hereinafter referred to as LDPE), LLDPE, EV
A, an ionomer, an ethylene / acrylic acid copolymer, an ethylene / methacrylic acid copolymer and the like can be suitably used.

Further, the film forming method of the composite film of the present invention is preferably a co-extrusion method.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0017]

(Example 1) A composite film having the following layer structure was co-extruded by the T-die method to a total thickness of 130 μm.
m of composite film was formed.

LLDPE (thickness 3 μm) / PP (thickness 30)
μm) / AD (7 μm thickness) / Ny (25 μm thickness) / E
VOH (thickness 15μm) / AD (thickness 10μm) / LLDP
E (thickness: 40 μm) (Example 2) A composite film having a total thickness of 130 μm was formed by co-extrusion of the composite film having the following layer constitution by a T-die method.

LLDPE (thickness 5 μm) / PP (thickness 35)
μm) / AD (thickness 10 μm) / EVOH (thickness 10 μm)
) / Ny (thickness 30 μm) / AD (thickness 10 μm) / LL
DPE (thickness 30 μm) (Comparative Example 1) A composite film having a total thickness of 130 μm was formed by co-extrusion of a composite film having the following layer structure by a water-cooled inflation method. PP (thickness 30 μm) / AD (thickness 10 μm) / EVOH
(Thickness 15μm) / Ny (thickness 25μm) / AD (thickness 10μm)
m) / LLDPE (thickness: 40 μm) (Comparative Example 2) A composite film having a total thickness of 120 μm was formed by co-extrusion of a composite film having the following layer structure by a water-cooled inflation method. LLDPE (thickness 15 μm) / AD (thickness 15 μm) / Ny
(Thickness 20μm) / EVOH (thickness 15μm) / AD (thickness
10 μm) / EVA (45 μm thickness) (Comparative Example 3) A composite film having a total thickness of 130 μm was formed by co-extrusion of a composite film having the following layer structure by a T-die method. LLDPE (thickness 3 μm) / PP (thickness 5 μm) / AD
(Thickness 5 μm) / EVOH (thickness 15 μm) / Ny (thickness
25 μm) / AD (10 μm thickness) / LLDPE (67 μm thickness)
m) (Comparative Example 4) A composite film having a total thickness of 130 µm was formed by co-extrusion of a composite film having the following layer constitution by a T-die method.

LLDPE (thickness 5 μm) / PP (thickness 50)
μm) / AD (thickness 15 μm) / Ny (thickness 15 μm) / E
VOH (thickness 10μm) / AD (thickness 10μm) / LLDP
E (thickness 25 μm) unstretched polypropylene film (hereinafter referred to as CPP) and K-coated cellophane (hereinafter referred to as KM);
A laminated body having the following configuration obtained by dry laminating LLDPE was used as a cover material.

CPP (thickness: 40 μm) // KM (thickness: 22 μm)
m) // LLDPE (thickness: 50 μm) Using the composite films of Examples 1 and 2 and Comparative Examples 1 to 4 as the bottom material, and using the lid material having the above configuration, a deep drawing packaging machine FV6
Hamburger (diameter 90)
(mm, thickness: 15 mm) was deep-drawn and packed to prepare a packed product (square: 14 cm × 11 cm, depth: 15 mm), and a test evaluation was performed.

<Evaluation Method> Transparency The haze of the seal portion of the packing product was measured. Those with a haze of good transparency of 7% or less were marked with a circle, and those with a haze exceeding 7% were marked with a cross. -Glossiness According to JISK7105.

A gloss mark of 125 or more was marked with a circle, and a gloss less than 115 was marked with a cross. -Flange curlability A flat material having no curl in the flange portion of the bottom material was marked with "O", and a curl in the flange portion was marked with "X". -Pinhole resistance (by the Gelboflex method) A 200 mm wide x 300 mm long film is heat-sealed to form a cylindrical body, and bent 1000 times at 20 ° C, 40 times / min.
Circles with five or less occurrences of pinholes were marked with a circle, and those with more than 10 pinholes were marked with a cross.

[0024]

[Table 1]

As shown in Table 1, the thickness of the outermost layer LLDPE is in the range of 1 to 10 μm, and LLDPE / PP /
The total thickness of AD is 15-40% of the total thickness of the composite film
In Examples 1 and 2 in the above range, the transparency and gloss were good, the curl of the flange portion did not occur, and the pinhole resistance was extremely good. Comparative Example 1 in which the outermost layer is a PP layer
Has good curl and pinhole resistance in the flange portion, but is inferior in transparency and gloss.

The total thickness of the outermost LLDPE is 1
In Comparative Example 2 having a thickness of more than 0 μm, transparency, gloss and pinhole resistance were good, but curling of the flange portion was inferior. LL
In Comparative Example 3 in which the total thickness of DPE / PP / AD was less than 15% of the total thickness of the composite film, the pinhole resistance, transparency, and gloss were good, but the curl of the flange portion was inferior, and LLD
Comparative Example 4 in which the total thickness of PE / PP / AD exceeds 40%
Has good transparency, gloss, and curl of the flange portion, but has poor pinhole resistance.

[0027]

As described above, according to the present invention, processed foods such as hamburgers and chickens for boil processing, prepared foods and the like are excellent in pinhole resistance, excellent in transparency and gloss without curling of the flange portion. Thus, a composite film for a boiled bottom material that is suitably used as a packaging bottom material can be obtained.

Claims (3)

[Claims] 1. An innermost layer is a heat sealing resin layer, an intermediate layer is a polyamide resin layer, and a linear low density polyethylene resin layer having a thickness of 1 to 10 μm is disposed as an outermost layer. A composite film for a boiled bottom material, comprising a polypropylene resin layer disposed adjacent to a high density polyethylene resin layer. 2. The total thickness of the outermost linear low-density polyethylene resin layer, the polypropylene resin layer, and the adhesive resin layer adjacent to the resin layer is 15 to 15 times the total thickness of the composite film.
The composite film for a boiled bottom material according to claim 1, which is 40%. 3. The composite film for a boiled bottom material according to claim 1, wherein a saponified ethylene-vinyl acetate copolymer resin layer is disposed on the intermediate layer.