JP2007039059A - Shrink package - Google Patents

Abstract

Disclosed is a shrink package that can be easily taken out without damaging the package, and can be reliably and easily opened even in the case of a laminated film, particularly when the film is easily peeled off.
A shrink wrapping body for wrapping an object to be packaged by a shrink film having at least two opposing V-shaped cuts and an adhesive structure covering the cuts. The packaged item is a container containing the contents, and can also be applied when the inside of the container is replaced with gas.
[Selection] Figure 2

Description

  The present invention relates to a shrink package having an easy-open function.

Generally, various packaging materials are used for the purpose of product protection. Among them, various thermoplastic resin films that are excellent in durability, transparency, and gloss and can be sealed by heat sealing are used regardless of the type of package. Widely used. In particular, a shrink package packaged with a heat-shrinkable film, which makes use of the point that it has a tight finish and is excellent in cosmetics and shrinks by heating with hot air or the like, is widely known.
However, the shrink package is in close contact with the film so as to clamp the package, and after shrinking, the thickness of the film increases. Therefore, the unsealing property of the film for taking out the package is poor. Furthermore, in the case of an irregularly shaped package, the degree of shrinkage of each part of the film is not uniform, so when tearing the film and taking out the package, the direction in which the film is torn is not determined, and as a result it is difficult to In reality, it is necessary to remove the film by putting in, and there are many cases where the unsealing property is difficult. When gas replacement packaging is used to maintain and improve the freshness of food, a strong film is used because the protection of the contents is more important, and its openability is more difficult. It has become a thing. As society ages and the birthrate is declining, easy-openability has become an extremely important issue in packaging.

Conventionally, the following are known as means for opening a package in which an article to be packaged is covered with a thermoplastic resin film.
(1) Tack label system (Patent Document 1)
In this type of opening means, a tongue piece is formed by cutting at the opening start point of the film covering the article to be packaged, and this tongue piece is covered and a tack label is attached to the outer surface side of the film. The unsealing is performed by peeling and pulling the tack label from the tip side of the tongue piece formed by cutting. That is, when the tack label is peeled off and pulled, the tongue piece is pulled while being stuck to the tack label, and the tearing of the film is started in the form of a narrow strip starting from the notch forming the tongue piece. Then, after the start of the tearing, the desired range is to be torn into a narrow band by the natural propagation action of the tear accompanying the pulling.
(2) Tack tape method (Patent Document 2, Patent Document 3)
The unsealing means of this system forms a tongue piece by a notch serving as an opening starting point for the film covering the article to be packaged, and attaches a tack tape whose one end is located on the tip side of the tongue piece in the opening direction, The film is torn and opened when peeled off from the tip of the tongue, but in addition, a strip-like perforation is formed so that it is covered with tack tape throughout the opening line. Means for tearing and opening the film along therewith are also disclosed.
(3) Tier tape method (Patent Document 4)
The unsealing means of this method is to apply a tear tape to the inner surface side of the film along the entire unsealing line of the film covering the article to be packaged, and to expose the end of the tear tape to the unsealing start side. A cut is formed in the film. The unsealing is performed by pulling the tear tape from the unsealing start side provided with the cut. That is, when the tear tape is pulled, the film is torn from the notch formed on the opening start side, and this is sequentially propagated along both sides of the tear tape to be opened.

However, the conventional opening means has the following problems.
(1) In the tuck label type opening means, there is no guide means after the start of tearing, and the film is intended to be opened in a strip shape only by the natural propagation action of the film tear, and the tear is narrow in one direction. In the case of an unwrapped package that can only be obtained in the form of a band, the direction of the tear is not fixed because the degree of shrinkage is different at each part of the film, and propagation is often interrupted immediately. Sex is inadequate. In particular, when the film has a multilayer structure and delamination is likely to occur, delamination occurs during propagation of film tearing, and propagation is likely to be interrupted. If the openability of the film covering the package is insufficient and the opening of the film covering the package is insufficient, for example, if the package is a tray pack with a sushi lid, it cannot be removed easily, and the If the film is broken, the sushi material may fall off or the sushi rolls over, which may significantly reduce the product value.

(2) Since the conventional tuck tape type opening means is basically open in only one direction, the degree of opening is insufficient to take out the contents as it is after opening, and a multilayer film was used in particular. In some cases, when film delamination occurs, only the release layer adhered to the tack tape causes tear propagation and cannot be opened. Also, in the case of shrink wrapping, when the degree of shrinkage differs in each part of the film, the directionality of opening using further tearing of the film to widen the opening after unidirectional opening with tape cannot be determined. Or with excessive force or difficulty. When peeling occurs, the opening is insufficient as described above. Moreover, when perforation is made in the form of a narrow band, there is a possibility that the gas substituted at the time of shrinking may leak when performing gas replacement shrink packaging.

(3) With the tear tape type unsealing means, it is necessary to affix the tear tape to the inner surface of the film before covering the article to be packaged with the film. In particular, film packaging is performed by heat-sealing as a sealing means. If a tear tape is applied to this heat-sealed part, the tear tape strength is significantly weakened at the time of heat-sealing, and the tear tape is applied to the part at the time of opening. May break and become unopenable.
As described above, it is possible to easily open a laminated film that easily causes delamination in various packages including gas replacement shrink packaging, which is useful for food preservation, and to easily take out a packaged item. A package that can be used is desired.
Japanese Patent Laid-Open No. 2003-20074 Japanese Utility Model Publication No. 61-134959 JP-A-3-28959 Japanese Utility Model Publication No. 61-12351

  It is an object of the present invention to allow a shrink wrapping body using a shrink film to be easily opened and taken out without damaging the package, and in particular, the shrink film is a laminated film, and the film is an interlayer. It is an object of the present invention to provide a shrink package that can be surely and easily opened even when it is easily peeled off.

That is, the present invention is as follows.
(1) A shrink package having at least two opposing V-shaped cuts, and the packaged article is packaged by a shrink film provided with an adhesive structure covering the cuts.
(2) The shrink package according to (1), wherein the V-shaped V-shaped angle is 10 to 120 °.
(3) The shrink package according to (1) or (2), wherein the package is a container containing the contents.
(4) The shrink package according to any one of (1) to (3), wherein the inside of the container containing the contents is gas-substituted.

  The most different point of the present invention from the prior art is that, firstly, the cut shape covered with an adhesive component such as a label has a specific cut shape having a V shape on the left and right, and secondly The label is peeled off, an opening is once formed in the packaging film, and then the end of the opening is pinched with fingers, and the film is torn in a double-folded form from side to side starting from the V shape. As a result, the package can be easily opened even if the above-mentioned problems that have conventionally occurred in a package using a heat-shrinkable film, and particularly the delamination found in a film having a multilayer structure, can be opened. It has the effect that it can take out easily, without damaging.

The present invention will be described in detail below, particularly focusing on preferred forms thereof.
The pressure-sensitive adhesive structure used in the present invention covers the cut of the shrink film, and is intended to start opening from the cut by peeling it off. It is preferable to provide a non-adhesive part in a part of the adhesive constituent because it can be peeled off from the starting point during opening. In the case of gas replacement packaging, the adhesive component also serves to prevent gas leakage.
An adhesion constituent consists of a base material and an adhesive, and a label form, a tape form, etc. are mentioned as a shape. Depending on the purpose, printing such as indicating the direction of peeling may be performed.
The adhesive construct preferably has a tensile strength that can withstand the tensile forces applied to tear the film from the cut. Examples of the material of the base material include plastics (which may include organic and inorganic fillers), simple substances such as metal and paper, or laminates thereof, and are commonly used films made of polyethylene terephthalate, polylactic acid. A known material such as a plant biodegradable resin film such as polypropylene, a polyolefin resin film such as polypropylene, or a laminate of these and paper can be appropriately used.

As the pressure-sensitive adhesive, known ones are used, and there are natural rubber-based, synthetic rubber-based, urethane-based and acrylic-based synthetic resins, polyvinyl alcohol-based water-soluble resins, and the like, which are appropriately selected according to the purpose. In the case of gas replacement packaging, in order to prevent gas from escaping from the gap of the cut portion, the adhesive structure must have a gas barrier property. Therefore, the material and thickness should be selected appropriately to achieve the desired gas barrier property. Is preferably ensured.
The adhesive strength of the adhesive structure to the film is preferably 3 times or more of the tear strength of the film, and if it is 3 times or more, the adhesive structure is peeled off during handling before opening after the adhesive structure is attached. In addition, at the time of opening, the pressure-sensitive adhesive structure is not peeled in the same manner due to the speed at which the pressure-sensitive adhesive structure is peeled off or the blur in the peeling direction. From the viewpoint of suppressing peeling after the pressure-sensitive adhesive structure is attached to the shrink film, it is preferably 5 times or more, and more preferably 10 times or more. The upper limit of the adhesive strength is not particularly limited, but in some cases, when repacking (repackaging), considering that it is peeled off from the film and reused, the adhesive strength is 1.5 kg / 15 mm width or less. Is more preferable, and 1.0 kg / 15 mm width or less is more preferable.

Here, the adhesive strength is a manual crimping device defined in JIS Z0237 with a label or tape cut into a strip shape with a width of 15 mm (a constant width as wide as possible 3 mm or more if 15 mm cannot be secured) with respect to the target film. (Mass 2000 g) is reciprocated once and pasted uniformly so as not to cause wrinkles or air accumulation. After standing for 2 hours, it means the peel strength when peeled 180 ° at a speed of 50 mm / min. It is a value proportionally converted to. The pasting and measurement are performed in an environment of 23 ° C. and 65% RH.
The tear strength of the film used in the present invention is determined according to JIS-P-8116 by using a light load tear tester (manufactured by Toyo Seiki Co., Ltd.) to peel off the adhesive component in order to form an opening in the present invention. Measure in the direction. In addition, although the reading of the measured value here is measured so that it may become the range of 20-60 of a scale, when there is a difference in a measured value by a measurement range, a higher value is measured. The film to be measured is the film on the upper surface of the package after shrink wrapping. In the present invention, the required strength as a package and the easy tearing property by pulling the adhesive component by hand are maintained. The thing of the range of-1500mN is preferable.

The pressure-sensitive adhesive composition used in the present invention may have various functions such as a gas indicator such as oxygen, carbon dioxide, and ethylene, and a deoxygenation function.
The incision according to the present invention is a portion to be peeled off integrally with the adhesive structure as a tongue piece. The shape has at least two opposing V-shapes as illustrated in FIG. Here, the opposing V-shapes are obtained by drawing a line (m, n) that bisects the corner (θ) with the V-shaped cut corners 1 and 2 as the tip, and bisecting the corner. A V-shape in which the lines cross each other. By having opposite V-shapes, it is possible to provide an index in the tearing direction and to form a tongue piece linearly.

The conventional incision is simply V-shaped or U-shaped as shown in FIG. 3, so there is no guide means after the start of tearing, and it will be opened into a narrow band only by the natural propagation action of the film tear. Since the direction of the tear is not determined, the propagation is often interrupted immediately, and the unsealing property is insufficient. In particular, when the film has a multilayer structure and delamination is likely to occur, delamination occurs during propagation of film tearing, and propagation is likely to be interrupted.
The V-shaped V-shape angle θ is preferably 10 to 120 °. When the V-shaped angle θ is larger than 10 °, it is easy to process the cut, and the tongue piece is more easily formed when the adhesive component is first peeled off. When the V-shaped angle θ is smaller than 120 °, the end of the film opening formed by peeling off the adhesive structure is pinched and the intended start of tearing of the film from the V-shape becomes easier. The more preferable V-shaped angle θ is 20 to 90 °, more preferably 25 to 70 °, from the stable formation of the tongue piece when the adhesive structure is peeled off and the certainty as the starting point of the tear.

  Examples of other cut shapes are shown in FIGS. 1B to 1G, but are not limited thereto. The V-shaped cut corners 1 and 2 may be rounded as shown in FIG. 1B, and the radius of curvature is preferably 3 mm or less. When the radius of curvature is 3 mm or less, the film as a starting point after opening the film becomes easy to tear and the easy-opening property is improved. As shown in FIG. 1C, the V-shaped cut corners 1 and 2 may be discontinuous, and the distance between the discontinuous portions is preferably within 5 mm, more preferably within 3 mm. FIG. 1D shows an example in which there are a plurality of opposing V-characters, and the number of left and right V-characters does not need to match, and even if the number of left and right V-characters is the same, the structure is an object. There is no need. As shown in FIG. 1 (e), the left and right may be asymmetric. Moreover, as shown in FIG.1 (f), the shape which tied the two V-shaped cut corner | angular parts 1 and 2 with the curve may be sufficient, and as shown in FIG.1 (g), two V-shaped The cut corners 1 and 2 may be connected by polygonal straight lines.

In the present invention, the incision having the specific shape that forms the tongue piece is covered with an adhesive component, and is perpendicular to the straight line connecting the cut end portions 3 and 3 ′ (see FIG. 1A) forming the tongue piece. After the adhesive structure is peeled off in the direction to form an opening in the film, the end of the film opening is pinched, and the film is shrunk in a double-spread form starting from the opposite V-shape It is preferable to open the package.
In order to make it easy to pinch the opening of the film, the preferable size of the notch of the present invention is preferably 5 mm or more, more preferably 10 mm in the peeling direction of the adhesive structure (between 1-3 ′ and 2-3). That's it. The linear distance (between 3-3 ′) at both ends of the cut is preferably 3 mm or more, more preferably 5 mm or more, and still more preferably 10 mm or more.

The method for opening the shrink package of the present invention will be specifically described below.
The package 10 of the present invention is composed of a shrink film 4, an adhesive component 5, an opposing V-shaped cut 6 and an article to be packaged, and the article to be packaged is preferably a container containing contents. For example, the packaging body 10 is provided with V-shaped notches 6 facing each other as shown in FIG. 1A on the top surface of the packaging body and is covered with the adhesive structure 5 (FIG. 2A). )reference). The packaged object in this case is a container with a lid, but in the present invention, a tray package without a lid may be used, or the contents may be directly packaged without using a tray or a lid. Moreover, although the attachment position of the V-shaped notch 6 and the adhesion | attachment structure 5 which oppose each other is not specifically limited, the package upper surface is preferable at the point of the ease of taking out to-be-packaged goods, and workability | operativity. It is more preferable that it is attached near the center between the center point of the upper surface and the side surface side part in terms of ease of taking out the package after opening.

For opening, first, the adhesive component 5 is peeled off from the long side to the short side of the opposing V-shaped cut 6 (see FIG. 2B). That is, the adhesive structure is peeled off in the direction perpendicular to the straight line connecting the opposite ends of the V-shaped cuts facing each other. At this time, the opposing V-shaped notch 6 covered with the adhesive component 5 and the strip-shaped portion including the notch extension newly formed by peeling are referred to as a tongue piece 8. Here, the length of the formed tongue piece 8 and the opening 7 formed by the tongue piece formation do not affect the opening procedure described later, and there is no problem even if the length is shortened by delamination of the film, for example.
Next, as shown in FIG. 2 (c), the V-shaped cut corner 1 is used as a starting point to open outward, and then the V-shaped cut corner 2 is also opened outward. It is preferable to open and open. The order of opening from the V-shaped cut corners 1 and 2 may be either. The state of the package opened in this way is shown in FIG. 2 (d). By tearing the shrink film 4 on the upper surface of the package in the double-sided opening direction 9, the tongue piece 8 and the tongue piece are separated by delamination as described above. Even when the opening 7 generated by the formation is shortened, the packaged item can be easily taken out without being damaged.

In the packaging process, the attachment time of the adhesive structure is not particularly limited, but in the case of gas replacement packaging in particular, there is a risk of gas leakage (intrusion of air) and film tearing from the cut portion, which will be described later. It is preferable that a cut is attached to the film before the preliminary packaging body to be obtained is attached, and the adhesive component is attached.
There is no restriction | limiting in particular if the shrink film which can be used for the package of this invention can be used for shrink packaging. In order to make the easy-openability of the present invention even more effective, the shrinkage of the film of the package after shrink wrapping is preferably 5% or more in any direction, more preferably 10% or more. 15% or more is more preferable. Thereby, the certainty of opening of the shrink package using the tear of the present invention is remarkably improved. The upper limit of the shrinkage rate is preferably 80% or less, more preferably 70% or less, still more preferably 60% or less, from the viewpoint of deformation of the container due to secondary shrinkage of the packaging film when heating in a microwave oven before opening. is there.

The shrinkage rate here means the thermal shrinkage rate of the film in the peripheral part including the opening part of the package after shrink wrapping. Usually, the film sample of 30 mm square is formed from the film forming the upper surface of the package. Take the sample and place it in an air oven-type thermostatic oven set at an arbitrary predetermined temperature up to 160 ° C and heat it for 30 minutes in a freely shrinkable state. Expressed as a percentage of the value divided by the original dimension.
When the inside of the container containing the contents is replaced with gas, a gas barrier shrink film conventionally used for gas replacement shrink packaging can be used. Gas barrier property, 23 ° C., preferably ^{30000ml / (m 2 · day ·} MPa) or less in oxygen permeability value at 65% RH, more preferably ^{10000ml / (m 2 · day ·} MPa) or less, more preferably 5000ml / (M ² · day · MPa) or less, most preferably 1000 ml / (m ² · day · MPa) or less. In addition, oxygen permeability is measured by the method of ASTM-D-3985.

Examples of gases used in gas replacement packaging include nitrogen, oxygen, carbon dioxide, argon, xenon, krypton, alcohols and allyl mustard oil, and these are used alone or in combination depending on the purpose. . As a gas replacement method, a gas flash method is generally used. However, for the purpose of improving the gas replacement rate, it is also possible to perform gas replacement by combining decompression treatment with an appropriate vacuum degree and gas flash.
A typical example of shrink wrapping used in the present invention is to wrap a container with a tray or a lid containing contents with a shrink film, seal the opening to form a preliminary wrapping body, pass through a hot air tunnel, The film is heat-shrinked while the air is evacuated from the provided deaeration holes or the deaeration holes provided after hermetically sealing, and is brought into close contact with the contents and the tray. In this shrink wrapping, when the flow (MD) seal is mainly sealed at the bottom of the pre-packed body and the front and rear sides are sealed horizontally (pillow wrapping method), the film is half-folded and the three sides that are the openings are sealed. In some cases (half-fold film method), two films are stacked and sealed on four sides (upper and lower film method).

As a typical example of the above-described gas replacement shrink wrapping, after replacing the inside of the container with a desired gas during the pillow wrapping, excess gas is discharged by pressing a sponge, etc., and at the same time, a pre-packaging body is formed by sealing and sealing. Then, the shrink wrap is obtained by passing through a hot air shrink tunnel.
In the present invention, in order to prevent breakage from the notches in the packaging and gas leakage (intrusion of air) from the notches during the gas replacement packaging, the gas replacement is performed particularly in the gas replacement packaging before obtaining the preliminary package. It is preferable to attach the notch and attach the adhesive structure that covers the notch before performing.

The present invention will be explained by examples and comparative examples.
The measuring method of each physical property value is as follows.
(1) Oxygen permeability Measured based on the method of ASTM-D-3985.
(2) Shrinkage rate After the shrink wrapping, the 30 mm square film sample is collected from the film forming the upper surface of the package including the unsealed portion of the package, and placed in an air oven type thermostatic chamber set at 140 ° C. A dimensional change in an arbitrary direction after heating for 30 minutes in a freely contractible state was obtained, and expressed as a percentage of a value obtained by dividing the shrinkage dimension by the original dimension.
(3) Tear strength According to JIS-P-8116, a light load tear tester (manufactured by Toyo Seiki Co., Ltd.) was used to measure the direction in which the adhesive component was peeled off in order to form an opening in the present invention. . In addition, although the reading of the measured value here performs a measurement so that it may become the range of 20-60 of a scale, when there is a difference in a measured value by a measurement range, the higher value shall be measured.
(4) Adhesive strength A manual crimping device (mass) as defined in JIS Z0237 with a label or tape cut into a strip with a width of 15 mm (a constant width as wide as possible 3 mm or more if 15 mm cannot be secured) against the target film. 2000g) is reciprocated once and attached uniformly so that there is no wrinkle or air accumulation. After leaving for 2 hours, the peel strength when peeled 180 ° at a speed of 50 mm / min is said to be proportionally converted to a width of 15 mm. Value. The pasting and measurement were performed in an environment of 23 ° C. and 65% RH.

[Example 1]
Using a gas-barrier shrink film, a package containing 100 g of tuna nigiri sushi in a polystyrene lid (120 mm x 70 mm x 20 mm in height) and an inorganic filler-filled polypropylene tray (120 mm x 70 mm x 20 mm in height) Using nitrogen gas as a filling gas, packaging was performed continuously at a rate of 30 packs per minute in a pillow shrink packaging machine capable of gas replacement by a gas flash method.
The film used was extruded and melted and stretched by a double bubble inflation method, and the layer structure was ethylene-α olefin copolymer / adhesive resin / polyamide resin / amorphous polyester / ethylene-vinyl alcohol copolymer ( EVOH) / adhesive resin / ethylene-α-olefin copolymer (innermost layer heat seal layer), each layer having a thickness ratio (%) of 10/5/20/15/10/5/35 and a thickness of 25 μm. Prepared and packaged using this. The oxygen permeability of this film was 200 ml / (m ² · day · MPa).
Prior to the packaging step, the film was provided with a trapezoidal cut (long side 20 mm, short side (linear distance between both ends of the cut) 10 mm, both V-shaped angles of 45 °) shown in FIG. For the adhesive structure, a polyethylene terephthalate adhesive tape (Nitto Denko Corporation holding tape No. 3800, thickness 55 μm × width 75 mm × 150 m, white) is processed to 40 mm × 30 mm, and a non-adhesive part is provided at the peeling start part. The adhesive label was prepared, this was attached, and shrink packaging was obtained by performing said packaging. The shrinkage ratio of the film on the upper surface of the shrink package was 13% in the flow (MD) direction, 16% in the width (TD) direction, the tear strength was 210 mN, and the adhesive strength of the label was 160 g / 15 mm width. At the time of opening, after peeling off the adhesive label to form an opening in the top film, pinching the edges of the opening and tearing the two corners of the cut into two sides on both sides, opening the sushi inside The packaged item could be easily taken out without rollover or collapse.

[Example 2]
The layer structure is polyamide resin / EVOH / adhesive resin / ethylene-α olefin copolymer (innermost layer heat seal layer), and the thickness ratio (%) of each layer is 40/10/5/45 and the thickness is 32 μm. A shrink package was obtained by packaging in the same manner as in Example 1 except that the film was used. The oxygen permeability of this film was 160 ml / (m ² · day · MPa). The shrinkage rate of the film on the upper surface of the shrink package was 8% in the flow (MD) direction, 8% in the width (TD) direction, the tear strength was 280 mN, and the adhesive strength of the label was 290 g / 15 mm width. Also at the time of opening, similarly to Example 1, the packaged item could be easily taken out without rolling and breaking the sushi inside.

[Example 3]
Packaging was carried out in the same manner as in Example 1 except that a polyethylene terephthalate pressure-sensitive adhesive tape (width 30 mm × length 80 mm × thickness 75 μm) was attached as the pressure-sensitive adhesive structure to obtain a shrink package. Also at the time of opening, similarly to Example 1, the packaged item could be easily taken out without rolling and breaking the sushi inside.

[Comparative Example 1]
A shrink package was obtained by packaging in the same manner as in Example 1 except that the cut was formed in the shape shown in FIG. At the time of opening, the sticky label was peeled off to form a tongue, but the packaged item could not be removed easily, and when the packaged item was removed by tearing the film by hand, the sushi inside turned over. have done.

  The shrink package of the present invention can be suitably used for the field of shrink packaging using a heat-shrinkable film, particularly for opening a package packaged with a tough film such as polyamide.

The figure which shows the example of the cut shape in this invention. The figure which shows the shrink package and opening method in this invention. The figure which shows the cutting shape used for the comparative example.

Explanation of symbols

1, 2: V-shaped cut corners 3, 3 ': Cut both ends 4: Shrink film 5: Adhesive structure 6: V-shaped cuts facing each other 7: Opening formed by tongue piece formation 8: Tongue Piece 9: facing direction 10: package

Claims (4)

  A shrink package having at least two opposing V-shaped cuts, wherein a packaged object is packaged by a shrink film provided with an adhesive structure covering the cuts.   The shrink package according to claim 1, wherein the V-shaped V-shaped angle is 10 to 120 °.   The shrink package according to claim 1 or 2, wherein the package is a container containing contents.   The shrink package according to any one of claims 1 to 3, wherein the inside of the container containing the contents is gas-substituted.

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