JP2003165571A - Packaging method and co-extrusion laminate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an article packaging method which can prevent foreign matters from entering, has easy-opening property such that a square-bottomed bag can be opened with its form kept and does not impair such convenience that the square-bottomed bag can be repeatedly opened/closed by a binding tool or the like, and a co-extrusion laminate film suitable for manufacturing the square-bottomed bag for use in the packaging method. <P>SOLUTION: The co-extrusion laminate film has a heat-seal resin layer (A) containing a block copolymer (a) consisting of an ethylene-propylene copolymer block and an ethylene-propylene copolymer block having a larger content of an ethylene-originated component than the former block, an intermediate resin layer (B) containing a propylene-based resin with a start-to-heat-seal temperature higher than that of the block copolymer (a), and a surface resin layer (C) with a thickness of 0.5 to 5 μm containing an ethylene-based resin. The packaging method comprises a step of heat-sealing an opening of a square-bottomed bag made of the film and filled with an article under easy-operable heating conditions to provide an easy-openable square-bottomed package. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for packaging foods such as bread and confectionery bread and other articles in a corner bottom packaging bag, and maintains the shape of the corner bottom packaging bag on the opening side. The present invention relates to a packaging method capable of preventing foreign matter from being mixed by providing an easily openable seal that can be opened up to the present, and a coextrusion laminated film suitable for manufacturing a square bottom bag used in this packaging method.

[0002]

2. Description of the Related Art Conventional square bottom packaging bags such as bread packaging and confectionery bread packaging are bound by a binding tool for twisting and fixing the opening, that is, a plastic plate, a tape, a string having a slit of about 2 cm square. It is sold. A large number of contents or a large number of contents, which can be opened and closed many times by a resealable binding tool, is highly convenient and is often used.

However, since the wrapping with such a binding tool is simple, there is a drawback that there is a gap in the binding portion of the square bottom packaging bag and it is impossible to prevent the entry of foreign matter. Therefore, an easy-open seal that can be opened while maintaining the shape of the square-bottom bag is provided on the opening side of the square-bottom packaging bag, and a packaging method that can prevent foreign matter from entering and the corner used for this packaging method. There is a strong need for coextruded laminated films suitable for making bottom bags.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent foreign matter from entering and to have an easy-opening property that allows opening while maintaining the shape of a square bottom bag. The object of the present invention is to provide a method for packaging an article that does not impair the convenience of opening and closing the square bottom bag, and a coextrusion laminated film suitable for manufacturing the square bottom bag used in this packaging method.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above situation, the inventors have found that a block of an ethylene-propylene copolymer and an ethylene-propylene copolymer having a larger content of ethylene-derived components than the block. A heat-sealing resin layer (A) containing an ethylene-propylene block copolymer (a) composed of a polymer block;
An intermediate resin layer (B) containing a propylene resin having a higher heat-sealing start temperature than the ethylene-propylene block copolymer (a), and a thickness of 0.5 to 0.5 containing the ethylene resin. (I) having a surface resin layer (C) of 5 μm is suitable for manufacturing a square-bottomed bag, and can prevent foreign matter from entering, and can be opened while maintaining the shape of the rectangular-bottomed bag. It has been found that the product is easy to open and can be easily packaged without impairing the convenience of opening and closing the square bottom bag many times with a binding tool or the like.

The reason therefor is that the heat-sealing resin layer (A) can be melt-bonded in a temperature range of 70 ° C. or higher, and in this temperature range, the bonding strength increases approximately in proportion to the melt-bonding temperature, and the high-temperature range is high. In the melt bonding in the above, the bonding strength is high and the bond is strong, but in the low temperature region, the bonding strength is weak and the easily-openable seal can be easily obtained. The heat seal resin layer (A) is used as the inside for melt cutting and bonding. However, when the melt-adhesion is performed with the surface resin layer (C) inside, the interlayer adhesive strength between the intermediate resin layer (B) and the surface resin layer (C) is low, and the surface resin layer is (C)
Since the thickness of the product is thin, the adhesive strength of the melt-cut adhesive joint becomes low and it breaks, so that a square-bottom bag can be easily obtained. The obtained square-bottom bag is filled with foods and other articles and opened at a low temperature. Part, for example, a stable easy-open seal can be obtained by heat-sealing the part between the upper end of the opening of the packaging bag and the filled food, and the easy-open square-bottomed packaging bag can be easily obtained. By binding the upper part with a tie, it is possible to make a bundled package similar to the conventional bread corner bottom packaging, and the obtained easy-opening square bottom packaging bag has an easy-opening seal to prevent the entry of foreign matter. In addition, it can be easily opened with the easy-open seal portion, and the bag is not damaged even if opened, so that it can be resealed with a binding tool such as a plastic plate, tape, or string.

Therefore, according to the present invention, the heat-sealing resin layer (A) of the coextrusion laminated film having the heat-sealing resin layer (A), the intermediate resin layer (B) and the surface resin layer (C) is melted and cut inside. Easy-open packaging by heat-sealing the opening of the square-bottom bag that has been adhered and made into a square-bottom bag and filled with articles under heating conditions that allow opening while maintaining the shape of the square-bottom bag. In addition, the coextrusion laminated film is composed of an ethylene-propylene copolymer block and an ethylene-propylene copolymer block having a higher content of ethylene-derived components than the block. Ethylene-propylene block copolymer (a)
A heat-sealing resin layer (A) containing a resin, and an intermediate resin layer (B) containing a propylene-based resin having a higher heat-sealing start temperature than the ethylene-propylene block copolymer (a). There is provided a packaging method, which is a coextrusion laminated film (I) having a surface resin layer (C) containing an ethylene resin and having a thickness of 0.5 to 5 μm.

Further, the present invention is an ethylene-propylene block copolymer comprising an ethylene-propylene copolymer block and an ethylene-propylene copolymer block having a higher content of ethylene-derived components than this block. Heat-sealing resin layer (A) containing (a)
And the ethylene-propylene block copolymer (a)
Having an intermediate resin layer (B) containing a propylene-based resin having a higher heat-sealing start temperature than that and a surface resin layer (C) containing an ethylene-based resin and having a thickness of 0.5 to 5 μm To provide a coextruded laminated film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The coextruded laminated film (I) used in the present invention comprises a block of ethylene-propylene copolymer and a block of ethylene-propylene copolymer in which the content of the ethylene-derived component is higher than that of this block. A heat-sealing resin layer (A) containing an ethylene-propylene block copolymer (a)
Intermediate resin layer (B) containing a propylene-based resin having a higher heat-sealing start temperature than the propylene-based block copolymer (a), and a surface having a thickness of 0.5 to 5 μm containing an ethylene-based resin It may have a resin layer (C).

The heat-sealing resin layer (A) is an ethylene-propylene series composed of an ethylene-propylene copolymer block and an ethylene-propylene copolymer block having a higher content of ethylene-derived components than the block. A resin layer containing the block copolymer (a) may be used, but a heat seal layer having excellent transparency and a lower heat seal starting temperature than the ethylene resin in the surface resin layer (C) can be obtained. Therefore, it contains ethylene-propylene rubber (EPR) together with the ethylene-propylene block copolymer (a) in a weight ratio (a) / (EPR) of 50/50 to 85/15. It is preferable that the resin layer is Further, as the heat-sealing resin layer (A), the heat-sealing temperature and strength at the time of easy-opening sealing at low temperature can be easily adjusted, the heat-sealing temperature range is wide, and the heat-sealing strength suitable as an easy-opening seal can be easily made. Since it is obtained, a part of the ethylene-propylene block copolymer (a) may be replaced with an ethylene-propylene block copolymer (ep) other than the ethylene-propylene block copolymer (a). it can. The weight ratio (a) / (ep) is preferably in the range of 30/70 to 95/5.

Further, as the heat-sealing resin layer (A), as the ethylene-propylene block copolymer (a), an ethylene-propylene block having an ethylene-derived component content of 1 to 6% by weight is used. And an ethylene-propylene block copolymer (a1) consisting of an ethylene-propylene copolymer block having an ethylene-derived component content of 7 to 25% by weight. The ethylene-propylene copolymer block (a11) having an ethylene-derived component content of 1 to 6% by weight, and the ethylene-derived component content of 7 to 25
Wt% ethylene-propylene copolymer block (a
The weight ratio (a11) / (a12) of 12) is 40/60 to 85 /
It is more preferable that the content of the ethylene-derived component is 2.5 to 5% by weight because the balance between transparency and impact resistance at low temperature is good, and the moldability is excellent.
Ethylene-propylene copolymer block (a13),
It is composed of an ethylene-propylene copolymer block (a14) having an ethylene-derived component content of 12 to 25% by weight, and the weight ratio of the block (a13) and the block (a14) (a
It is particularly preferable that 13) / (a14) is 70/30 to 85/15 and the difference in the content ratio of the ethylene-derived components of the block (a13) and the block (a14) is 7 to 21% by weight.

The method for producing the ethylene-propylene block copolymer (a) used in the heat-sealing resin layer (A) is not particularly limited, but, for example, the presence of a Ziegler-Natta catalyst and the absence of an inert solvent. Below, an ethylene-propylene copolymer, preferably an ethylene-propylene copolymer having an ethylene-derived component content of 1 to 6% by weight,
Copolymerize to 40-85% by weight of the total copolymer,
Then, in the gas phase, an ethylene-propylene copolymer having a higher content of ethylene-derived components, preferably an ethylene-propylene copolymer having a content of ethylene-derived components of 7 to 25% by weight, is a total copolymer. And a method of copolymerizing the content of 60 to 15% by weight.

As the ethylene-propylene copolymer (ep) used in combination with the ethylene-propylene block copolymer (a) in the heat seal resin layer (A),
There is no particular limitation as long as it is an ethylene-propylene copolymer other than the ethylene-propylene block copolymer (a), and examples thereof include ethylene-propylene random copolymer, ethylene-propylene rubber (EPR), and the like. Among them, ethylene-propylene rubber (EP
R) is particularly preferred.

The heat seal resin layer (A) is
It is particularly desirable that the heat-sealing start temperature is lower than the heat-sealing start temperature of the intermediate resin layer (B) because it facilitates the production of the square bottom packaging bag and the easy-open seal.
Therefore, the coextruded laminated film (I) of the present invention comprises a propylene-based resin having a higher heat-sealing start temperature than the ethylene-propylene block copolymer (a) contained in the heat-sealing resin layer (A). It is contained in the intermediate resin layer (B), and above all, the heat seal resin layer (A)
And the heat seal start temperature difference between the intermediate resin layer (B) and 1
The temperature is preferably 0 ° C. or higher.

The heat-sealing start temperature in the present invention is the heat-sealing start temperature measured according to the heat-sealing start temperature test defined in JIS K-1713.

The intermediate resin layer (B) is a resin layer containing a propylene-based resin having a heat-sealing start temperature higher than that of the ethylene-propylene block copolymer (a) in the heat-sealing resin layer (A). As long as, for example,
Propylene homopolymer; ethylene-propylene block copolymer (a) such as ethylene-propylene copolymer, polyethylene-polypropylene block copolymer, and copolymer of propylene and α-olefin other than ethylene And a resin layer containing at least one propylene-based resin as a main component, such as a propylene-based copolymer having a high heat-sealing start temperature; and the like, and among them, a propylene homopolymer (b1) and / or ethylene. −
An ethylene-propylene-based copolymer (b) having a higher heat-sealing start temperature than the propylene-based block copolymer (a)
A resin layer containing 2) is preferable, and examples of the ethylene-propylene copolymer (b2) include ethylene-propylene copolymers having an ethylene-derived component content of 2 to 10% by weight. Further, as the intermediate resin layer (B), the propylene-based resin as described above as a main component is 75
It is preferably contained in an amount of not less than wt%, and if necessary, other thermoplastic resins such as ethylene-1-butene copolymer, linear low-density polyethylene, and various additives can be mixed.

The intermediate resin layer (B) is a resin composed of two layers, an intermediate resin layer (B1) on the heat seal resin layer (A) side and an intermediate resin layer (B2) on the surface resin layer (C) side. It may be a layer. In this case, the intermediate resin layer (B2) on the surface resin layer (C) side preferably has the same composition as that described as the intermediate resin layer (B). In this case, the heat seal resin layer (A ) Side intermediate resin layer (B1)
As, for example, propylene homopolymer, ethylene-
Propylene-based copolymer, polyethylene-polypropylene-based block copolymer, α-other than propylene and ethylene
The main component is at least 70% by weight of at least one propylene-based resin such as a copolymer with an olefin, and if necessary, an ethylene-1-butene-based copolymer, a straight chain Other resin such as low density polyethylene or the like, and a resin layer formed by mixing recovered materials generated during the production of the present laminated film are included. Further, the intermediate resin layer (B1) may be a resin layer having the same composition as the intermediate resin layer (B2). Specifically, when a coextruded laminated film having excellent rigidity is desired, a composition in which the intermediate resin layer (B1) has excellent rigidity as compared with the intermediate resin layer (B2), for example, a composition mainly containing a propylene homopolymer, is used. In the case where a laminated film having excellent cold resistance is desired, the intermediate resin layer (B1) has a composition excellent in low temperature impact resistance as compared with the intermediate surface layer (B2), for example, linear low It is preferable to use a resin layer having a composition containing density polyethylene.

Further, the intermediate resin layer (B1) can be divided into two or more layers, and there is no problem even if the layer structure of the entire intermediate resin layer (B) is three or more layers.

The surface resin layer (C) may be a resin layer (C) containing an ethylene resin and having a thickness of 0.5 to 5 μm, and examples thereof include low density polyethylene, medium density polyethylene and high density. 80 based on one or more ethylene-based resins such as polyethylene and linear low-density polyethylene
A resin layer having a thickness of 0.5 to 5 μm and preferably a thickness of 1 to 3.5 μm, which is contained in an amount of not less than wt%, can be mentioned. Among them, the adhesiveness to the intermediate resin layer (B) is low, and the adhesive strength of the melt-cut adhesive portion of the square-bottom bag formed by melt-cut adhesion with the surface resin layer (C) inside is 2.5 N. / 15 mm or less is preferably a resin layer made of an ethylene resin, for example, a density of 0.910 to 0.930 g / cm ^3.
The resin layer made of low-density polyethylene can be used.

Further, the surface resin layer (C) is a resin layer having a higher heat-sealing start temperature than the heat-sealing resin layer (A), so that the appearance of the square bottom bag filled with the article has a good appearance. A heat-sealable resin containing an ethylene-propylene block copolymer (a) and an ethylene-propylene rubber (EPR) is preferable as such an easy-open seal can be easily formed. A layer, preferably a heat seal resin layer having a weight ratio (a) / (EPR) of 50/50 to 85/15,
A combination with a surface resin layer made of low-density polyethylene having a density of 0.910 to 0.930 g / cm ³ can be mentioned.

The surface resin layer (C) can be embossed to form a resin layer having a matte surface, whereby a coextruded laminated film having a matte surface and a square bottom bag. Can be obtained.

The thickness of the coextruded laminated film (I) according to the present invention is usually 20 to 50 μm, and above all 25 to 50 μm.
40 μm is preferable. Also, the heat seal resin layer (A)
The thickness is usually 0.1 to 10 μm, but in particular 1
-8 μm is preferable.

Coextruded laminated film (I) according to the present invention
Is a four-layer film laminated in the order of (A) / (B1) / (B2) / (C), the thickness ratio of the intermediate resin layer (B1) and the intermediate resin layer (B2) to the total thickness is It depends on the resin composition of each layer and is not particularly limited, but the intermediate resin layer (B1) is usually 30 to 80%, preferably 40 to 70%.
And the content of the intermediate resin layer (B2) is usually 10 to 50%, preferably 15 to 45%.

Specific examples of the laminated film (I) according to the present invention include, for example, an ethylene-propylene block copolymer (a),
A heat-sealing resin layer (A-1) containing ethylene-propylene rubber (EPR) in a weight ratio (a) / (EPR) of 50/50 to 85/15, and a propylene homopolymer. An intermediate resin layer (B-1) containing 70% by weight or more of (b1) and a density of 0.910 to 0.9
The surface resin layer (C-1) made of 30 g / cm ³ of low-density polyethylene is (A-1) / (B-1) / (C-
In the order of 1), the ratio of the average thickness is 1.2 / 8.3 / 0.
A three-layer film (I-
1), the heat seal resin layer (A-1), a linear low-density polyethylene and an ethylene-propylene copolymer (b)
2) and an intermediate resin layer (B1-2) containing 70% by weight or more of the ethylene-propylene copolymer (b2), and a propylene homopolymer and / or an ethylene-propylene copolymer. The intermediate resin layer (B2-2) containing 75% by weight or more of the polymer (b) and the surface resin layer (C-1) are (A-1) / (B1-2) / (B
2-2) / (C-1) are laminated in this order,
For example, the thickness is 25 μm or 30 which is formed by stacking so that the ratio of the average thickness is 1 / 5.5 / 3 / 0.5.
4 layer film (I-2) suitable for a square bottom bag of μm,
And so on.

Coextruded laminated film (I) according to the present invention
May be used as it is, but the surface resin layer (C) may be subjected to corona discharge treatment in order to improve the appeal of the product by printing. Moreover, in each layer of the coextrusion laminated film (I),
If necessary, additives such as an antioxidant, a slip agent, an antiblocking agent, an antifogging agent, a colorant, and silica may be appropriately added within the scope of the present invention.

The method for producing the coextruded laminated film (I) according to the present invention is not particularly limited as long as it is a coextrusion molding method. For example, melt extrusion is performed using three or more extruders, coextrusion. Preferred is a method of laminating in a molten state by a known coextrusion method such as a multilayer die method or a feed block method, and then processing the film into a long roll film by a method such as inflation or T-die / chill roll method.

The packaging method of the present invention using the coextruded laminated film (I) as described above is as follows. The heat-sealing resin layer (A) of the coextruded laminated film (I) is melt-cut and adhered inside to form a square bottom. By a packaging method in which the opening of the square bottom bag, which is made as a bag and is filled with articles, is heat-sealed under heating conditions such that the shape of the square bottom bag can be opened and easily opened. It is sufficient if the heat-sealing resin layer (A) is inside, and the adhesive strength of the melt-cut adhering portion of the square-bottom bag formed by melt-cut adhering is 8.5 to 30 N / 15 m.
m, and the adhesive strength of the melt-cut adhering portion of the square-bottom bag formed by melt-cut adhering with the surface resin layer (C) as the inside is 2.5 N / 15 mm or less, and the article was filled. The heat-sealing strength of the easy-open seal part obtained by heat-sealing the opening of the square bottom bag is 0.1 to 5 N / 15 m.
m is preferable, and among them, the adhesive strength of the melt-cut adhesive portion of the square bottom bag is 9 to 20 N / 15 mm, and the heat-sealing strength of the easy-open seal portion is 0.2 to 3.5 N.
It is particularly preferable that it is / 15 mm. Then, after heat-sealing the opening of the square bottom bag, the upper part of the article may be bound with a binding tool, which allows the bag to be resealed after opening using the binding tool.

The packaging method of the present invention using the coextruded laminated film (I) is described below, and the bread packaging method using the three-layer film (I-1) or the four-layer film (I-2) is described below. This will be explained by exemplifying

Bread packaging method For the bread packaging method, it is preferable to use the three-layer film (I-1) or the four-layer film (I-2). When the three-layer film (I-1) or the four-layer film (I-2) is used, these co-extruded laminated films are printed and then the heat-sealing resin layer is inside the bag. Machine such as H manufactured by Totani Giken Co., Ltd.
It is processed into a square bottom bag with K-40V. At this time, the adhesive strength of the melt-bonded portion of the square bottom bag formed by melt cutting and bonding with the heat seal resin layer (A) as the inside is 8.5 to 30 N /
It is preferable to adjust the melt cutting adhesion temperature, bag making speed, etc. under the condition of 15 mm. Then, the obtained square bottom bag is
The bread is supplied to an automatic bread filling machine, and after filling the bread, it is preferably heat-sealed under the condition that the heat-sealing strength is 0.1 to 5 N / 15 mm to form an easily openable bread-wrapping square bottom bag, and if necessary, At the upper part of the square bottom bag, preferably at the upper part of the bread, the easily openable seal part or the upper part or the lower part thereof is bound using a binding tool such as a plastic plate, tape or string.

The easy-open seal referred to in the present invention means that the heat-sealing strength of a test piece having a width of 15 mm cut out from the heat-sealed portion of the bag is measured by a tensile tester [Tensilon manufactured by A & D Co., Ltd.]. With a temperature of 23 ° C. and a pulling speed of 300 mm / min, the heat seal strength is 0.1 to 5 N / 15 mm, and 80% or more of the test pieces are from the sealing surface without breakage of the film. This is a heat seal for peeling.

In the bread packaging method described above, the heat sealing after filling the bread is easy to open and has a heat sealing strength of 0.
The sealing temperature and the sealing time to be 1 to 5 N / 15 mm are not particularly limited, depending on the sealing pattern and the sealing pressure, but preferably 70 to 108 ° C.
In 0.1 to 2 seconds.

[0032]

EXAMPLES The present invention will be described more specifically below with reference to Examples and Comparative Examples. The parts and% in the examples are
All are by weight unless otherwise noted.

Example 1 As a heat-sealing resin layer (A), an ethylene-propylene copolymer block having an ethylene-derived component content of 4.0% and an ethylene-propylene copolymer having an ethylene-derived component content of 18% were used. Ethylene-propylene block copolymer consisting of copolymer block [density: 0.90 g /
cm ³ , melt index (hereinafter referred to as MI)
(Measurement temperature 230 ° C.): 3 g / 10 minutes] 80 parts and ethylene-propylene rubber (EPR) (density: 0.88 g /
cm ³ , MI (measurement temperature 230 ° C.): 5 g / 10 minutes)
And a propylene homopolymer (density: 0.90 g / cm 2) as a mixture of 20 parts and an intermediate resin layer (B).
³ , MI (measurement temperature 230 ℃): 9g / 10 minutes),
Furthermore, as the surface resin layer (C), low-density polyethylene [density: 0.91 g / cm ³ , MI (measurement temperature 190 ° C.):
4 g / 10 minutes] to each of three extruders,
The heat-sealing resin layer (A), the intermediate resin layer (B), and the surface resin layer (C) were co-extruded to have an average thickness ratio of 1.2: 8.3: 0.5 and a thickness of 30 μm. Was molded into a three-layer film.

Surface resin layer (C) of the obtained three-layer film
The surface energy of the surface resin layer (C) is 36 mN / m
Was subjected to corona discharge treatment to obtain a laminated film for a square bottom bag. After aging this laminated film at 35 ° C. for 48 hours, the film was half-folded with the heat-sealing resin layer (A) inside, and the inside of the fold was folded to form a double-folded bottom portion. Both isosceles isosceles right-angled isosceles triangles having the inner fold of the bottom as the apex and the outer fold as the base are melt-cut and bonded (hereinafter referred to as V-seal) at the temperature shown in Table 1, and then the right-angled isosceles. Bag-making by passing through the apex of a triangle and at right angles to the flow direction at the temperature shown in Table 1 (hereinafter referred to as side seal) [bag-making machine: HK-manufactured by Totani Giken Co., Ltd.]
40 V, bag making speed: 130 sheets / min], and then a square bottom bag (vertical:
345 mm, width: 235 mm) was obtained.

After filling the obtained square bottom bag with bread, a heat sealer [tester industry] is provided between the upper end of the opening and the loaf of bread (a portion 50 mm below the upper end of the opening) in parallel with the opening.
Co., Ltd., pressure: 0.2 MPa, time: 1 second, sealing temperature: the temperature of the upper seal bar is the temperature shown in Table 1, the lower seal bar is fixed at 50 ° C., seal bar shape: 300 m
m × 10 mm flat surface] for easy opening and heat sealing to obtain an easily openable bread packaging square bottom bag. Using this easy-open square bread bag, the V-seal strength, side seal strength, and easy-open heat-sealing strength were measured as follows.
The presence or absence of film breakage during the easy-open heat-sealing strength measurement was observed. The results are shown in Table 1 (1) and (2).

* V-seal strength and side-seal strength: a width of 15 mm from the center of the V-seal portions on both sides of the obtained five square bottom bags and from the center of the side-seal portions on both sides above the V-seal portion. Test pieces one by one (two each in one bag), cut out a total of 10 each, 23 ℃,
The maximum load at the time of peeling was measured with a Tensilon tensile tester [manufactured by A & D Co., Ltd.] under the condition of a tensile speed of 300 mm / min, and the results were taken as V seal strength and side seal strength, respectively.

* Easy-open heat-sealing strength: 15 m from each of the obtained easy-open-heat-sealed portions of the five square bottom bags.
Two m-width test pieces (two easy-open heat-seal parts
Divided into equal parts, one from the center), 10 in total
Tensiron tensile tester (manufactured by A & D Co., Ltd.) under the conditions of 23 ° C. and a pulling speed of 300 mm / min.
The maximum load at the time of peeling was measured and used as the easy-open heat seal strength. Also, the presence or absence of breakage of the test piece during the easy-open heat-sealing strength measurement was observed, and those peeled off without film breakage were evaluated as “no breakage”, and those broken off were evaluated as “breakaged”.

Comparative Example 1 As a heat seal resin layer (A), a propylene-ethylene copolymer (content of ethylene-derived component: 3.7%, density:
0.90 g / cm ³ , MI (measurement temperature 230 ° C.): 8 g
/ 10 minutes), and the ratio of the average thickness of the heat seal resin layer (A), the intermediate resin layer (B) and the surface resin layer (C) is 3:
A laminated film was produced in exactly the same manner as in Example 1 except that the ratio was changed to 6.5: 0.5, and the seal strength was measured in the same manner to evaluate the presence or absence of film breakage. The results are shown in Table 1 (1) and (2).

[0039]

[Table 1]

[0040]

[Table 2]

As can be seen from the results of Table 1 (1) to (2), the square bottom bag obtained using the coextruded laminated film (I) of the present invention is a square bottom bag obtained by the conventional laminated film. The same sufficient V-sealing strength and side-sealing strength as described above can be obtained, and moreover, if the opening of the bag is heat-sealed at 80 ° C., the film can be peeled off from the sealing surface without breaking and the easy-opening property can be obtained.

[0042]

The packaging method of the present invention forms a double-folded bottom portion for a square-bottomed bag so that the heat-sealing resin layer (A) of the coextruded laminated film (I) is on the inside of the bag. When the melt cutting adhesive for the bag is used, the melt cutting adhesive portion having the heat seal resin layer (A) inside is firmly adhered, but the melt cutting adhesive portion having the surface resin layer (C) inside is weakly adhered. In addition to easily obtaining a square-bottom bag, filling the obtained square-bottom bag with an article such as food and heat-sealing the opening at a lower temperature enables stable easy-opening and heat-sealing. It can be an easy-open packaging bag in which food is sealed. The obtained easy-opening square-bottomed packaging bag is easy-opening heat-sealed to prevent foreign matter from entering, and can be easily opened at the easy-opening heat-sealed portion, and the square-bottomed bag is not damaged even if opened. Therefore, it is possible to reseal with a binding tool such as a plastic plate, a tape, and a string, and by binding the upper part of the bag with the binding tool, it is possible to obtain the same binding packaging as the conventional bread packaging.

The packaging method and the coextruded laminated film of the present invention have a great practical value, especially, for twist bag packaging and horizontal pillow packaging of bread, snacks, fruits and vegetables.

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[Procedure amendment]

[Submission date] February 27, 2002 (2002.2.2)
7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Packaging method and coextrusion laminated film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B65D 33/30 B65D 33/30 4F207 65/40 65/40 D 4J002 75/60 75/60 C08L 53/00 C08L 53/00 // B65D 85/36 B65D 85/36 A (C08L 53/00 C08L 23:16 23:16) B29K 23:00 B29K 23:00 B29L 7:00 B29L 7:00 9:00 9:00 F-term (reference) 3E064 AB03 BA22 BB03 BC16 BC18 EA18 FA01 HN06 HN38 3E067 AA25 AB01 BA12A BB14A BB25A CA24 DA01 EA01 EA06 EB01 EB25 EC29 FA01 FB20 FC01 3E086 AA23 AC07 AC22 AC31 AD01 BA04 BA15 BB51 BB68 BB90 CA01 DA08 3E096 BA28 BB08 BB09 CA12 CA22 CB03 CC01 DA18 DB01 DC01 EA02X FA20 FA22 FA27 FA40 GA01 4F100 AK04C AK06C AK07B AK64A AK64B AL02A AL05A AL05B AN02A BA03 BA07 BA10A BA10C BA15 DA01 DD01C EH20 EJ55 GB16 GB23 HB 21C JA15C JA20A JA20C JK06 JL11 JL12 JL12A JL12B JL14 YY00 YY00A YY00C 4F207 AA04 AA07 AG01 AG03 AH54 KA01 KA17 KB26 KW42 4J002 BB15Y BP02W BP02X GF00 GG02

Claims (13)

[Claims] 1. A heat-sealing resin layer (A), an intermediate resin layer (B), and a surface resin layer (C) having a heat-sealing resin layer (A) of a coextrusion laminated film as an inner side, and melt cutting and adhering to form a corner. A packaging method in which the opening of a square bottom bag, which is made into a bottom bag and is filled with articles, is heat-sealed under a heating condition such that the shape of the square bottom bag can be opened to provide an easy-open packaging. In addition, the coextruded laminated film has a block of ethylene-propylene copolymer and an ethylene-containing component having a larger content of ethylene-derived components than the block.
A heat-sealing resin layer (A) containing an ethylene-propylene block copolymer (a) consisting of a block of a propylene copolymer, and a heat-sealing layer rather than the ethylene-propylene block copolymer (a). Intermediate resin layer (B) containing a propylene-based resin having a high starting temperature
And a thickness of 0.5 to 5 μm containing an ethylene resin
A packaging method comprising: a coextrusion laminated film (I) having the surface resin layer (C) of 1. 2. The heat seal resin layer (A) is a resin layer containing ethylene-propylene rubber (EPR) together with the ethylene-propylene block copolymer (a), and the weight ratio (a) thereof. / (EPR) is 50 / 50-8
The packaging method according to claim 1, which is 5/15. 3. The heat seal resin layer (A) comprises an ethylene-propylene copolymer block having an ethylene-derived component content of 1 to 6% by weight and an ethylene-derived component content of 7.
Is a resin layer containing an ethylene-propylene block copolymer (a1) composed of 25 to 25% by weight of an ethylene-propylene copolymer block and ethylene-propylene rubber (EPR), and an intermediate resin layer ( B) is an ethylene-propylene-based copolymer (b) having a higher heat-sealing start temperature than the propylene homopolymer (b1) and / or the ethylene-propylene-based block copolymer (a1).
The packaging according to claim 2, which is a resin layer containing 2) and the surface resin layer (C) is a resin layer made of low density polyethylene having a density of 0.910 to 0.930 g / cm ^2. Method. 4. The adhesive strength of a melt-cut adhesive portion of a square-bottom bag formed by melt cutting and adhering the heat-sealing resin layer (A) of the coextruded laminated film (I) inside is 8.5 to 30 N /.
The heat-sealing strength is 15 mm, and the heat-sealing strength of the easy-open seal portion obtained by heat-sealing the opening of the bag filled with the article is 0.1 to 5 N / 15 mm.
The packaging method according to 2 or 3. 5. The opening of the square bottom bag is 70 to 108 ° C.
The packaging method according to claim 4, wherein heat-sealing is carried out under the condition of 1 to 2 seconds to form an easily opened square bottom package. 6. The coextruded laminated film (I) has a thickness of 20.
The packaging method according to claim 4, wherein the heat-sealing resin layer (A) has a thickness of 1 to 8 μm. 7. The packaging method according to claim 4, wherein the surface resin layer (C) is a resin layer having a matte surface formed by embossing. 8. The packaging method according to claim 4, wherein after heat-sealing the opening of the bag filled with the article, the upper part of the article is bound with a binding tool. 9. An ethylene-propylene block copolymer (a) comprising an ethylene-propylene copolymer block and an ethylene-propylene copolymer block having a higher content of ethylene-derived components than this block. A heat-sealing resin layer (A) containing, an intermediate resin layer (B) containing a propylene-based resin having a higher heat-sealing start temperature than the ethylene-propylene block copolymer (a), and ethylene A coextrusion laminated film comprising a surface resin layer (C) containing a resin and having a thickness of 0.5 to 5 μm. 10. The heat-sealing resin layer (A) is a resin layer containing ethylene-propylene rubber (EPR) together with the ethylene-propylene block copolymer (a), and the weight ratio (a) thereof. / (EPR) is 50/50 ~
The coextruded laminated film according to claim 9, which is 85/15. 11. The heat seal resin layer (A) comprises an ethylene-propylene copolymer block having an ethylene-derived component content of 1 to 6% by weight and ethylene having an ethylene-derived component content of 7 to 25% by weight. -A resin layer containing an ethylene-propylene block copolymer (a1) composed of a propylene copolymer block and an ethylene-propylene rubber (EPR), wherein the intermediate resin layer (B) is propylene alone. The ethylene-propylene copolymer (b) having a higher heat-sealing start temperature than the polymer (b1) and / or the ethylene-propylene block copolymer (a1).
The resin layer containing 2) and the surface resin layer (C) is a resin layer made of low density polyethylene having a density of 0.910 to 0.930 g / cm ^2.
The coextruded laminated film described. 12. A thickness of 20 to 50 μm, and
The thickness of the heat seal resin layer (A) is 1 to 8 μm,
The coextrusion laminated film according to claim 9, 10 or 11. 13. The surface resin layer (C) is a resin layer having a matte surface formed by embossing.
The coextrusion laminated film according to the item.