JPH09234815A - Laminate for easily openable sealant, packaging bag and lid using the same - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide an easily-openable sealant laminate, which is easy and smooth to open, and has an aesthetically good opening surface, and an easily-openable package using the same. The purpose is to provide. In a laminated film in which two different types of resin layers (a) and (b) are adjacent to each other, the lamination strength between the resin layers (a) and (b) is 50 gf / 15 mm.
Above, and by heat sealing, the laminating strength between the resin layers (a) and (b) is at least 20 gf / 15 mm compared with the laminating strength before heat sealing.
The resin layer (a) that is smaller than the above and after heat sealing
The laminate strength between (b) is 10 to 500 gf / 15 m
m is an easily-openable sealant laminate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealant laminate, and more particularly, to an easily-openable sealant laminate that can be easily and smoothly opened and a package that can be easily opened.

[0002]

2. Description of the Related Art A packaging bag represented by snacks such as potato chips blocks the outside air to prevent oxidization of the contents in order to prevent alteration of the contents, or prevents the contents from being accelerated by shading. It also prevents the quality of the contents from deteriorating due to moisture absorption during storage or conversely drying. The method of sealing these packaging bags by heat-sealing with a sealant layer applied to the inner surface is generally used. Therefore, in order to achieve the above-mentioned object, the sealant layer needs to have a sufficient sealing property, and also has a sufficient heat-sealing strength so that the seal portion does not come off during the process of transportation or the like. It is said that.

However, the excessive heat sealing strength for protecting the contents cannot be opened easily by hand when used by the consumer, and it is less necessary to use tools such as scissors. There wasn't. In addition, even if it can be opened, it requires a large amount of force when opening, and the content pops out at the moment of opening, and the opening interface is cohesively destroyed, which is not aesthetically pleasing. It was From such a problem, there has been proposed a sealant in a packaging bag that can maintain the sufficient airtightness to protect the contents and can be easily opened by hand.

As a proposal for easy opening of a sealant in a packaging bag, a proposal has been made for a long time to reduce the heat seal strength by blending a resin composition of a sealant layer with a polymer or the like. However, unlike the bonding of different polymers such as the relationship between the cup container and the lid material, the packaging bag is bonded to the same polymer, and therefore has not yet been provided with the easy-open function. In addition, when the packaging bag is opened, stringing may occur at the adhesive interface between the sealant layers, which is not aesthetically pleasing and may cause the threaded resin to be mixed into the contents.

Further, in the lid material of the plastic container,
Base material, blend layer using polypropylene as a base resin,
A method has been proposed in which a blend layer and a polypropylene layer are laminated on a base material by co-extrusion so as to be laminated with a polypropylene layer, and delamination is performed between the blend layer and the polypropylene layer to impart easy opening property. There is.
However, there are still problems to be solved, such as stringing between the blend layer and the polypropylene layer, and lack of easy opening property.

Further, it has been proposed that the sealant layer and the peeling layer be replaced with each other to provide an easy-opening function by making the sealant layer multi-layered and reducing the laminating strength of the innermost layer and the intermediate layer adjacent to the innermost layer. . However, if the laminating strength is reduced, there are problems that the innermost layer remains as a film at the time of opening and the opening is not actually performed, and that the innermost layer is pulled at the time of opening and it is difficult to open.

[0007]

In view of the above-mentioned problems, the present invention is characterized in that the opening is easy and smooth, and the opening surface is aesthetically good. An object is to provide a body and an easily openable package using the body.

[0008]

SUMMARY OF THE INVENTION The present invention was conceived to solve the above problems. In the invention of claim 1, two different types of resin layers (a) and (b) are adjacent to each other. In the laminated film, the laminate strength between the resin layers (a) and (b) is 50 gf / 15 mm or more, and
By heat sealing, the laminating strength between the resin layers (a) and (b) is at least 20 gf / 15 mm or more smaller than the laminating strength before heat sealing, and the resin layers (a) and (b) after heat sealing. It is a laminate for an easy-open sealant, which has a laminate strength of 10 to 500 gf / 15 mm. The invention according to claim 2 is characterized in that the resin layer (a) is made of an ethylene-α-olefin copolymer and the resin layer (b) is made of polypropylene. is there. The invention according to claim 3 is the laminate for an easily-openable sealant according to claim 1, wherein the resin layer (a) is made of low-density polyethylene and the resin layer (b) is made of polypropylene. The invention of claim 4 is the laminate for an easily-openable sealant according to claim 1, wherein the resin layer (a) is made of linear low-density polyethylene and the resin layer (b) is made of polypropylene. The invention of claim 5 is a packaging bag comprising a base material and a sheet using the laminate for an easily openable sealant according to any one of claims 1 to 4 as an adhesive layer. A sixth aspect of the present invention is a lid member, which uses, as a bonding layer, the substrate for an easily openable sealant according to any one of the first to fourth aspects as a base material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below.

The laminate strength before heat sealing between two different types of resin layers (a) and (b) is 50 gf / 15 mm.
As described above, preferably 100 gf / 15 mm or more. Further, the resin layers (a) and (b) are heat-sealed, so that the resin layers (a) and (b) have a laminate strength of at least 20 gf / 15 mm or more, preferably at least 20 gf / 15 mm, as compared with the laminate strength before heat-sealing. 50gf / 15m
It is desirable to be smaller than m. The difference in laminating strength between the resin layers (a) and (b) before and after heat sealing is 20 g
If it is smaller than f / 15 mm, the resin layer (b) becomes difficult to cut from the edge portion of the heat-sealed portion, so that easy opening cannot be performed. The laminate strength after heat sealing is 10 to 500 gf / 15 mm, preferably 50 to 30
0 gf / 15 mm is desirable. Resin layer (a) when the laminate strength after heat sealing is less than 10 g / 15 mm
(B) Delamination easily occurs between the
If it is larger than 500 gf / 15 mm, the resin layer (a)
Since the peel strength between the layers between (b) is too large, it becomes difficult to open.

Laminate strength is JIS K6854
The measurement is performed by a method based on (9.2 T-type peel test). However, in this case, the width of the test piece is 15 ± 0.5 m
It is performed in the form of a strip of m. For the measurement, attach the test piece to the grip of the tester, and move the crosshead at a speed of 100 ± 10 mm.
And continue until the rest of the bonded portion is 10 mm. And regarding the processing of measurement results,
Based on K6854 (10.1 peeling load measurement)
Processing is performed by any one of the area method, the equal division method, and the optimal straight line method.

Examples of heat sealing methods include bar sealing, rotary roll sealing, sliding nip sealing, impulse sealing, fusing sealing, heat melting sealing, ultrasonic sealing and high frequency sealing.

As the base material, a single base material such as biaxially oriented polyester, biaxially oriented polypropylene or biaxially oriented nylon can be used. Further, a base material having a multi-layered structure such as a case where biaxially oriented polyesters are laminated or a case where biaxially oriented polypropylene, polyethylene and biaxially oriented polyester are sequentially laminated can be used.

As the two different resins of the present invention, two different resins are selected from the resin group of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-α-olefin copolymer, polyester, polystyrene and polyamide. be able to. Here, the density of polyethylene is 0.905 or more, and low density polyethylene, medium density polyethylene, high density polyethylene,
Linear low density polyethylene and blends of these can be used. As the polypropylene, polypropylene having a density of 0.900 or more and composed of homo, random, and block can be used. The ethylene-vinyl acetate copolymer has a vinyl acetate content of 5
Less than 0% resin can be used. As the ethylene-α olefin copolymer, a resin which is amorphous or low crystalline and has a density of less than 0.900 can be used. As the polyester, crystalline or amorphous polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate can be used. Furthermore, nylon mn and nylon n can be used as the polyamide. Particularly preferred is a laminate of a blend layer of low density polyethylene and linear low density polyethylene and polypropylene. Further, a laminated body of an ethylene-α-olefin copolymer layer and a polypropylene layer is preferable.

As a method for molding the laminate for an easily-openable sealant in the present invention, the resin layers (a) and (b) can be coextruded by an inflation method or a T-die method. Further, the laminated body for an easily openable sealant formed with the base material may be dry-laminated or further sand-laminated. When used by laminating with other base material, a method of directly co-extruding and laminating on the base material or laminating the resin layer (a) on the base material, and then further laminating the resin layer (b) in order. Good.

The interface where both layers of the laminate composed of at least two kinds of different resin layers as described above are in contact with each other,
Bonded by physical entanglement. The physical entanglement consists of both macro entanglement such as anchoring effect and micro entanglement such as diffusion of molecules into an adjacent layer.

The physical entanglement is due to the molding temperature (usually 30 ° C. higher than the melting point of the resin) when the laminate is molded by coextrusion or when the laminates are sequentially laminated.
~ 200 ℃ higher temperature), in the state where the interface of both layers is melted,
While being macroscopically and microscopically entering each other's layers, they are cooled and solidified. When the interface of this laminate is heated again by heat sealing, the physical entanglement is relaxed, and the laminate strength of both layers is reduced. Therefore, it is considered that the greater the difference between the temperature for producing the laminate of the present invention and the heat-sealing temperature, the greater the change in laminate strength due to heat-sealing.

When the laminate for an easy-open sealant according to the present invention is laminated with a base material to form a bag, the innermost layers of the laminate for an easy-open sealant are strongly sealed by heat sealing. In the opening of the bag, the heat-sealed portion and the non-heat-sealed portion have different laminating strengths between different resin layers in the easily-openable sealant laminate, and the heat-sealing portion has a different laminating strength. Since it is weaker, the innermost layer film is more easily cut by the shearing force and the pulling force than the heat-sealed edge portion. When the different resin layers are peeled between adjacent layers and the peeling reaches the seal edge on the opposite side again, the innermost layer film is cut and opened due to the difference in the laminating strength from the portion not heat-sealed.

At this time, since the resin layer (a) is exposed on the surface of the interface where the peeling is performed, the appearance is not deteriorated.

[0020]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited thereto.

Example 1 A stretched polyester film having a thickness of 12 μm was used as a base material, and L5816 (density 0.9) manufactured by Sumitomo Chemical Co., Ltd. was used as low density polyethylene on the base material.
17, melt flow rate 10) with a thickness of 15 μm,
FL2 made by Mitsubishi Chemical Corporation as polypropylene for the innermost layer
5R (density 0.89, melt flow rate 23 (230
(° C.)) Co-extrusion was performed so that the layers were sequentially laminated with a thickness of 20 μm to prepare a laminated three-layer film.

With respect to the laminate thus prepared, low density polyethylene (L5816) and polypropylene (FL25
As a result of measuring the laminate strength between the layers in contact with R), it was 50 gf / 15 mm.

With respect to the laminate thus prepared, the surfaces of the coextruded polypropylene were put together and heat-sealed at 155 ° C. to prepare a 20 × 15 cm gassho-bonding bag as shown in FIG. At this time, as a result of measuring the laminating strength of low density polyethylene (L5816) and polypropylene (FL25R) after being heat-sealed, 2
It was 0 gf / 15 mm.

As a result of attempting to open the pouch with the joint-sealed joint, the bag was easily opened and the opening feeling was smooth.
Further, the polypropylene of the innermost layer was cut from the seal edge portion, and the low-density polyethylene was exposed on the peeling surface, and the appearance was also good.

<Example 2> As an ethylene-α-olefin copolymer, Tuffmer A408 manufactured by Mitsui Petrochemical Co., Ltd.
5 (density 0.88, melt flow rate 6.7) 7μ
m, and as polypropylene, FX4 (density 0.89, melt flow rate 6 (230 ° C.)) manufactured by Mitsubishi Chemical Co., Ltd. was coextruded at a thickness of 20 μm to form a multilayer film, A four-layer film was produced by sand-laminating the ethylene-α-olefin copolymer layer (Toughmer A4085) side of the prepared multilayer film with the substrate in Example 1 with 15 μm polyethylene.

With respect to the laminate thus prepared, ethylene-
The laminate strength between the layers in which the α-olefin copolymer (Toughmer A4085) and polypropylene (FX4) were in contact was measured, and the result was 400 gf / 15 mm.

Polypropylene (FX4) surfaces that were co-extruded were put together on the thus-prepared laminate and heat-sealed at 160 ° C. to prepare a 20 × 15 cm joint-bonding bag. At this time, the heat-sealed ethylene-α-olefin copolymer after heat-sealing (Tufmer A
4085) and polypropylene (FX4) were in contact with each other at a laminate strength of 200 gf / 15 mm.

As a result of attempting to open the pouch with the jointed palm, it was possible to easily open it and the feeling of opening was smooth.
Further, the polypropylene of the innermost layer was cut from the seal edge portion, and the ethylene-α-olefin layer was exposed on the peeled surface, and the appearance was also good.

[0029]

In the laminate of the present invention, since the seal layer and the peeling layer are different from each other, the heat-sealing strength is not dominated, and the innermost layer is easily cut from the edge of the heat-sealed portion to smoothly. It is opened, and the functions of both protection (sealing property) and easy opening property of the contents are secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a laminate according to the present invention.

FIG. 2 is a plan view showing an example of a packaging bag according to the present invention. a, b: Resin layer 1: Glue-on bonding bag 2: Upper and lower sealing parts 3: Back sealing part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B65D 65/40 B65D 65/40 F 77/20 77/20 L

Claims (6)

[Claims] 1. A laminated film in which two different types of resin layers (a) and (b) are adjacent to each other, and the lamination strength between the resin layers (a) and (b) is 50 gf / 15 mm.
Above, and by heat sealing, the laminating strength between the resin layers (a) and (b) is at least 20 gf / 15 mm compared with the laminating strength before heat sealing.
The resin layer (a) that is smaller than the above and after heat sealing
The laminate strength between (b) is 10 to 500 gf / 15 m
m is a laminate for an easily-openable sealant. 2. The laminate for an easily-openable sealant according to claim 1, wherein the resin layer (a) is made of an ethylene-α-olefin copolymer and the resin layer (b) is made of polypropylene. 3. The laminate for an easy-open sealant according to claim 1, wherein the resin layer (a) is made of low density polyethylene and the resin layer (b) is made of polypropylene. 4. A laminate for an easily-openable sealant according to claim 1, wherein the resin layer (a) is made of linear low density polyethylene and the resin layer (b) is made of polypropylene. 5. A packaging bag comprising a base material and a sheet using the laminate for an easily openable sealant according to any one of claims 1 to 4 as an adhesive layer. 6. A lid member using a laminate for an easily-openable sealant according to any one of claims 1 to 4 as an adhesive layer on a base material.