JP2003341689A - Packaging bag and package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easy-to-unseal packaging bag as an interior bag for a bag-in-carton and a bag-in-box, which is free from leakage of contents and has sufficient heat-sealability. <P>SOLUTION: The packaging bag is formed by overlaying two or more laminate films and fusion-welding their facing layers as a seal layer. The seal layer includes a first heat seal which contains 95 to 70 wt.% of a polyethylene with a density of 0.900 to 0.940 g/cm<SP>3</SP>and 5 to 30 wt.% of a polybutene-1 with a density of 0.880 to 0.920 g/cm<SP>3</SP>and is heat-sealed at a sealing temperature in a range with approximately proportional relation between the sealing temperature and seal strength, and a second heat seal which is heat-sealed at a sealing temperature in a range where the seal strength is approximately saturated for the rise in the sealing temperature. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging bag and a package having an easy-open property, and can be suitably used as an interior bag used in, for example, a bag in carton or a bag in box.

[0002]

BACKGROUND ART Conventionally, a so-called bag-in-carton or bag-in-box is used as a packaging form for a liquid such as a beverage and a gel-like semi-solid body such as butter and cream. This bag-in-carton or bag-in-box consists of a resin inner bag that stores a liquid or a semi-solid body and prevents leakage to the outside of the package, and a corrugated cardboard that prevents the inner bag from being broken by a force acting from the outside. And an exterior body formed of the same.

The film constituting such an inner bag for a bag-in-box is required to have film strength, heat sealability when formed into a bag, and the like in order to prevent leakage of stored items. As the film used for this interior bag,
For example, the EV disclosed in JP-A-59-64357.
Coextrusion film of A and polyethylene, JP-A-4-1-1
Ethylene-α is added to LLDPE disclosed in Japanese Patent No. 63041.
-A multilayer film provided with an intermediate layer containing an olefin polymer rubber, a film made of a resin composition obtained by mixing a specific LLDPE with a soft resin having a specific polypropylene diameter, as disclosed in JP-A-9-328582, is known. There is.

Further, in Japanese Patent Laid-Open No. 2000-153591, a laminated film in which a three-layer sandwich structure is formed of polyethylene layers, in particular, the density of polyethylene forming three inner and outer layers is the polyethylene forming the intermediate layer. A laminated film having a density higher than that of the above has been proposed. These films are mentioned as suitable as films for bag-in-cartons and bag-in-boxes, and it is essentially required to secure heat-sealing strength.

By the way, in the inner bag used for the bag-in-carton and bag-in-box, the inner bag for storing liquid such as wine and juice is poured into a part of the inner bag made of resin such as polypropylene and polyethylene. It is widely known that a mouth is integrally provided and a screw cap can be attached to the spout. on the other hand,
The inner bag for storing semi-solids such as butter and cream cannot be pulled out from the spout by tilting the container like liquid, so the inner bag should be broken before use to take out the stored items. There is.

[0006]

However, it is necessary to use a cutter, a blade or the like in order to take out the stored contents by breaking the inner bag having the heat-sealing strength as mentioned above, and the unsealing work becomes complicated. There is a problem. In particular, restaurants, food factories, etc. use a large amount of butter, cream, etc., so there is a high possibility that they will be purchased in the form of bag-in-cartons or bag-in-boxes, and opening them with a cutter etc. takes time and effort. There's a problem.
In addition, as disclosed in Japanese Patent Laid-Open No. 9-12059,
A film that has an easy-peel property at the end of the inner bag and is opened from there has also been proposed, but it is difficult to manufacture the film, and the manufacturing and material costs will rise, so it is practical It is hard to say.

An object of the present invention is to provide an inner bag for a bag-in-carton or a bag-in-box, which has a sufficient heat-sealing property so that stored items do not leak and which can be easily opened, and the packaging bag. To provide a package.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that when polyethylene and polybutene-1 are mixed, a temperature range in which the relationship between the seal temperature and the seal strength is approximately proportional is produced. It came to come to the idea. Specifically, the packaging bag of the present invention is a packaging bag constructed by laminating two or more laminated films and welding the layers facing each other as a sealing layer, and the sealing layer has a density of 0. 900 g / cm ^{3 to} 0.940 g / c
Polybutene having a polyethylene content of m ³ of 95 wt% to 70 wt% and a density of 0.880 g / cm ^{3 to} 0.920 g / cm ³
1 to 5 wt% to 30 wt%, the first heat-sealed portion heat-sealed at a seal temperature in a range where the relationship between the seal temperature and the seal strength is in a substantially proportional relationship, and the seal strength is substantially saturated with an increase in the seal temperature. And a second heat-sealing portion heat-sealed at a sealing temperature in the above range.

Here, the sealing temperature of the first heat-sealing portion may be in a range in which the sealing strength rises as the sealing temperature rises, and the relationship between the two needs to be perfectly proportional. Instead, for example, it also includes the case where the seal strength changes in a two-time function with respect to the seal temperature. Further, the sealing temperature of the second heat-sealing portion may be, as long as it is a region where the films are completely tightly sealed, and a range in which the sealing strength is substantially saturated with an increase in the sealing temperature, specifically, When the test piece including the heat-sealed portion is pulled, the film may be stretched so that the seal strength does not increase.

Further, the blending amount of polybutene-1 is 30 wt.
If it exceeds%, the heat seal strength in the saturated region cannot be secured, and it becomes unsuitable for packaging heavy goods. When the content of both of polybutene-1 is less than 5 wt%, the above-mentioned range of the substantially proportional relationship occurs only in an extremely narrow temperature range, and it becomes difficult to control the sealing strength of the first heat-sealing portion.

Further, the curve representing the relationship between the seal temperature and the seal strength has a slope of 1.18 N in the range of a substantially proportional relationship.
/ 15 mm width / ° C (120 gf / 15 mm width / ° C converted to SI unit) or less, and the seal strength at 120 ° C is 7.85 N / 15 mm width (800 gf / 15 mm width is S
It is preferably not less than the value (converted into I units). Further, a more preferable blending ratio of the polyethylene and the polybutene-1 is 93 wt% to 80 wt% of polyethylene,
Polybutene-1 is 7 wt% to 20 wt%. The packaging bag includes a bottom portion arranged to face the opening into which the stored item is inserted, and a side portion formed so as to surround the bottom portion and defining an opening at an end opposite to the bottom portion. In this case, it is preferable that the welding of the side portion and / or the bottom portion is configured by the second heat seal portion, and the welding of the side portions that close the opening portion is configured by the first heat seal portion.

According to the present invention, the second heat-sealing portion seals the bottom and sides of the packaging bag where heat-sealing strength is required, and the opening and other parts need easy peeling. Since the portion can be sealed by the first sealing portion, it is possible to obtain a packaging bag having good openability while ensuring the heat-sealing strength of the packaging bag. Further, since it suffices to use such a material structure as the seal layer, it is not necessary to form the easy peel layer on a part of the normal heat seal layer, and the material cost and the manufacturing cost can be significantly reduced. .

In the above, as the laminated film constituting the packaging bag, it is preferable to adopt a laminated film having a three-layer structure in which the sealing layer is an inner layer and an intermediate layer and an outer layer. The intermediate layer has a density of 0.915 g / cm ^{3 to} 0.
945 g / cm ³ , preferably 0.920 g / cm ^{3 to} 0.9
It is preferable to adopt polyethylene of 40 g / cm ³ ,
For example, LLDPE (Linear Low Density Polyethylen
e), any one of low-density polyethylene and high-density polyethylene, or a mixture thereof can be adopted. Among these intermediate layers, by particularly using high-density polyethylene, the laminated film constituting the packaging bag can be made to have elasticity, so that the easy peeling property at the time of opening can be improved.

The outer layer has a density of 0.900 g / cm ³ to
It is preferable to use 0.940 g / cm ³ of polyethylene, and more preferably, 20 parts by weight or less of ethylene-α-olefin copolymer elastomer is added to 100 parts by weight of polyethylene. Good.
By adopting polyethylene with the ethylene-α-olefin copolymer elastomer thus added, when heat-sealing the gusset fold of the packaging bag often used in bag-in-carton and bag-in-box,
Since the overlapping part of the outer layers can be heat-sealed,
The sealability of the gusset folded portion can be improved.

The thickness of the laminated film constituting the packaging bag of the present invention can be appropriately selected depending on the use and the size of the bag, but is preferably 30 μm to 200 μm,
More preferably, it is 40 μm to 100 μm.
Further, the inner layer and the outer layer preferably account for 5% to 40% of the total film thickness, and more preferably 10% to 30%. Further, the film is not limited to a two-layer or three-layer structure, and a gas barrier film layer such as nylon may be further provided as needed.

The laminated film constituting the packaging bag is manufactured by inflation molding, T-die extrusion molding,
Various methods such as laminate molding can be adopted.
Moreover, you may add the additives for films, such as an antiblocking agent, a slip agent, and a coloring agent, to each layer of a laminated film as needed.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples and specific examples, but the present invention is not limited thereto. I. Production of Laminated Film [Example 1 and Example 2] A laminated film 1 including an inner layer 11, an intermediate layer 12 and an outer layer 13 shown in FIG. 1 was formed into a tubular film having a folding width of 1500 mm by three-layer coextrusion inflation molding. Manufactured. Co-extrusion molding was performed so that the inner side of the tubular film was the inner layer 11 and the outer side was the outer layer 13. The film thickness is 60 μm, and the ratio of each layer is as follows: inner layer / middle layer / outer layer = 25% / 50% / 25
%. Example 1 and Example 2 are different from each other in the material configuration of the inner layer 11, and Table 1 shows specific materials of each layer.

[Comparative Example 1] Inner layer 1 of Examples 1 and 2
LLDP without adding polybutene etc. added to 1
The inner layer is formed only by E, and the others are the examples 1 and 2.
A laminated film was formed by the same method as. Table 1 shows the specific material constitution of the laminated film.

[0019]

[Table 1]

In Table 1, the following materials were used for LLDPE, HDPE, polybutene, elastomer, anti-blocking agent, slip agent and colorant. The density of the following materials is measured according to JIS K7112, and MFR (Melt Flow Ratio) is measured according to JIS K7112.
It carried out according to 7210. (1) LLDPE: Idemitsu Petrochemical Co., Ltd. MORET
EC IDEMITSUL 0138H (Density 0.91
7 g / cm ³ , MFR 1.3 g / 10 min) (2) HDPE: Idemitsu Petrochemical Co., Ltd. IDEMIT
SU HD (density 0.947 g / cm ³ , MFR 0.21
g / 10 minutes)

(3) Polybutene: manufactured by Mitsui Chemicals, Inc. Tuffmer BL BL-3110 (density 0.910 g / c)
m ^3, MFR1.0g / 10 min) (4) Elastomer: Mitsui Chemicals, Inc. TAFMER A-
4085 (density 0.880 g / cm ³ , MFR 3.6 g /
10 minutes) (5) Anti-blocking agent: added by a master batch of 15 wt%. (6) Slip agent: Added by a master batch of 5 wt%. (7) Colorant: added by a master batch of 60 wt%.

II. Bag production The tubular film 1 produced in Example 1, Example 2 and Comparative Example 1 was gusset-folded inside at both side folded portions as shown in FIG. 2 to obtain the tubular film 1 shown in FIG. The lower edge D has a temperature of 120 ° C. and a pressure of 19.6 N / cm ² (2 kgf / cm
² was converted to SI unit) and heat-sealed to form a bag bottom (second heat-sealed portion). Subsequently, each bag was filled with a viscous substance, and the upper edge U of the bag was heated at a temperature of 110 ° C. and a pressure of 1
9.6 N / cm ² (2 kgf / cm ² converted to SI unit)
And heat-sealed to close the opening (first heat-sealed portion).

III. Evaluation method (1) Measurement of inclination of seal strength Using a thermal inclination tester manufactured by Toyo Seiki, the seal curves of the inner layer 11 materials of Example 1, Example 2 and Comparative Example 1 were measured to create a quadratic approximation curve. The slope of the seal curve with respect to the seal temperature at a seal strength of 2.94 N / 15 mm width (300 gf / 15 mm width converted into SI unit) was determined. The quadratic approximation curve created to obtain the slope is shown in FIG. (2) Measurement of Seal Strength Regarding the bags of each Example and Comparative Example 1, the bags were cut so that the first heat-sealed portion had a width of 15 mm, and at the same time, the second heat-sealed portion had a width of 15 mm. Was cut out to prepare a test piece, and the film end portion of each test piece was pulled by Tensilon to measure the load at which the heat-sealed portion was broken. The results of each test are shown in Table 2.

[0024]

[Table 2]

In Table 2, "to or more" means that the film was stretched during the tensile test and further measurement of the seal strength was impossible.

IV. Evaluation Results As can be seen from the graphs of Example 1 and Example 2 in FIG. 4, by adding polybutene to the inner layer 11, a portion where the relationship between the seal temperature and the seal strength is substantially proportional is developed in the seal curve. There is. Therefore, by using this portion as the first heat seal portion, 4.90 N / 15
mm width (value of 500 gf / 15 mm width converted to SI unit)
Since it is possible to form a pseudo fused portion called
It can be seen that the openability of the heat-sealed portion can be improved. On the other hand, in Comparative Example 1, since the rising edge of the seal curve is steep, the seal temperature is set to 110.
If the temperature is lowered to 0 ° C., the fusion does not occur, so that the pseudo fused portion cannot be formed.

Further, comparing Example 1 and Example 2, in the case of Example 2, by adding an elastomer in addition to polybutene, the sealing strength at 120 ° C. appears as material destruction of the film. Considering this, it is considered that the film strength is improved.

[0028]

According to the present invention as described above, the second heat seal portion seals a portion such as the bottom portion and the side portion of the packaging bag which needs to secure the heat seal strength, and the easy peeling property of the opening portion and the like. Since it is possible to seal the necessary portion with the first sealing portion, while ensuring the heat sealing strength of the packaging bag,
A packaging bag having a good openability can be obtained.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram showing a bag manufacturing method in the above-mentioned embodiment.

FIG. 3 is a schematic diagram showing a heat-sealed portion in the embodiment.

FIG. 4 is a graph showing the relationship between the seal temperature and the seal strength in the above example.

[Explanation of symbols]

1 laminated film 11 Seal layer U First heat seal part D Second heat seal part

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3E064 AA13 BA26 BA60 BB01 BC18                       EA21 EA30 FA04 FA05 HN06                       HP10                 3E067 AA03 AA04 AB14 AB26 BA06C                       BA12B BB01C BB15B BB25B                       BB30B CA24 EA06 EA11                       ED08 FA04 FB15 FC01 GD07                       GD08                 3E086 AA02 AB01 AC07 AD01 BA04                       BA15 BB51 CA01 CA11                 4F100 AK04A AK04B AK09A AK09B                       AL05A AL05B BA02 BA06                       BA16 GB16 JA13A JA13B                       JL12 YY00A YY00B

Claims (4)

[Claims] 1. A packaging bag constituted by laminating two or more laminated films, and welding layers facing each other as sealing layers, wherein the sealing layers have a density of 0.900 g / cm ^{3 to} 0. 940
polyethylene 95 wt% of g / cm ³ ~70wt%, and the polybutene-1 of the density 0.880g / cm ³ ~0.920g / cm ³ comprises 5 wt% 30 wt%, almost the relationship between the sealing temperature and the sealing strength A first heat-sealing portion heat-sealed at a sealing temperature in a proportional range and a second heat-sealing portion heat-sealing at a sealing temperature in which the sealing strength is substantially saturated with an increase in the sealing temperature are provided. A packaging bag characterized by that. 2. The packaging bag according to claim 1, wherein the curve representing the relationship between the seal temperature and the seal strength has a slope in the range of approximately proportional relationship of 1.18 N / 15 mm width / ° C.
And the sealing strength at 120 ° C is 7.85N
A packaging bag having a width of 15 mm or more. 3. The packaging bag according to claim 1 or 2, wherein a bottom portion is arranged so as to face an opening for inserting a stored item, and a side opposite to the bottom portion is formed so as to surround the bottom portion. And a side portion that defines the opening portion at an end portion thereof, the welding of the side portion and / or the bottom portion is configured by the second heat seal portion, and the welding of the side portions that close the opening portion is A packaging bag comprising a first heat seal portion. 4. A packaging body comprising the packaging bag according to any one of claims 1 to 3 as an interior bag, and an exterior body covering the interior bag.