JP4563132B2 - Shrink wrap - Google Patents

Description

  For example, the present invention wraps an object to be packaged such as a container including a food containing itself or a tray containing contents such as food with a heat-shrinkable film, and then heat-shrinks the heat-shrinkable film into the object to be packaged. It is related with the closely-packed package.

  In general, for packaging of fresh foods and processed foods sold at supermarkets and convenience stores, etc., shrink packaging that is packaged with a heat-shrinkable film is widely known, taking advantage of its tight finish and excellent cosmetics. . For example, the shrink wrapping includes a tray containing contents and a heat shrinkable film, and the opening is hermetically sealed to form a pre-packaging body. The film is heat-shrinked while venting air from the deaeration holes provided thereafter, and is brought into close contact with the contents and the tray. In this shrink wrapping, when the vertical seal and the front and rear two sides are mainly sealed at the bottom of the pre-packed body (pillow wrapping method), the film is folded in half and the three sides that are the openings are sealed ( (Half-fold film system), two films are stacked and sealed on four sides (upper and lower film system), and the like. All of these methods are unsuitable as food packaging that dislikes the invasion of germs and the like because the film is provided with holes for deaeration in order to exclude air inside the package during heat shrinkage. Patent document 1 is disclosed as a packaging method in which the hole for deaeration is not provided.

This method uses a heat-shrinkable biaxially stretched plastic film with specified heat shrinkage rate and tensile recovery after heat shrink, wraps the tray containing the contents, degasses the interior, and opens the opening. After sealing and forming a preform having a hermetic seal portion on the side of the tray, the plastic film on the lower surface of the tray of the preform is heat-shrinked to attract the side hermetic seal portion downward, This is a packaging method in which the plastic film on the tray upper surface side is thermally shrunk.
In this method, since there is no hole for deaeration, it is easy to maintain hygienic conditions when packaging food, the side sealing seal does not move up to the upper surface of the package, and the appearance deteriorates due to pressing marks. Because it is difficult to occur, high merchantability and display effect are exhibited.

  On the other hand, in order to meet consumer needs such as food safety, security, and deliciousness, food additives, especially foods that do not use preservatives, have increased, and packaging methods to ensure safe and freshness have become even more important. It is coming. Among these, gas replacement packaging can maintain the freshness of food for a long period of time, and is frequently used as an effective packaging method that complements the effects of the above preservatives. Patent Document 2 is disclosed as a packaging method capable of gas replacement, and a tray containing contents is wrapped with a heat shrinkable multilayer film including a barrier resin layer and a heat sealable resin layer by a pillow packaging machine. The packaging method includes heat sealing the film at the bottom and the edge of the tray. According to this method, there is a description that a tray package that has excellent airtightness and can be stored for a long period of time is obtained, and that the shelf life of food is greatly improved when the inside of the package is replaced with gas.

However, in any of the packaging methods described in Patent Document 1 and Patent Document 2, the package obtained after heat shrinkage is more particularly in the case of a rounded or rounded container having a large curvature at the corner. The higher the thickness, the more the film is not contracted at the corners, and the film remains in a projecting shape (hereinafter referred to as a projecting product), which impairs the appearance or is adjacent to the other end of the projecting product during transportation. There is a problem that the body is scratched or a pinhole is generated due to repeated bending of the protrusion.
Furthermore, in order to open the package, it is necessary to break the film with a finger in the gap between the film and the packaged object, and in the case of a tough film, it is torn with scissors or a cooking knife. There are also problems in terms of usability.
JP-A-9-99908 JP-A-4-327153

  An object of the present invention is to provide a package that is excellent in appearance after heat shrinkage regardless of the contents of food or the like or the shape of a container, can greatly improve the occurrence of pinholes, and is excellent in easy opening. To do.

That is, the present invention is as follows.
1. A shrink-wrapped package formed by packaging heat-shrinkable films having different heat-seal temperatures on both surface layers, and a cylindrical heat-shrinkable film having an outermost layer having a higher heat-seal temperature than the innermost layer. It has a gusset-shaped hermetic seal part in which at least one of both ends of the tubular film is folded inward from the side surface, and the tip of the hermetic seal part is outward. Shrink wrapping body characterized by being divided into a Y shape toward
2. 1. The hermetic seal portion is located below . Shrink-wrapped body according to.
3. 1. The heat-shrinkable film has a gas barrier property. Or 2. The shrink wrap body described in 1.
4). 1. The heat shrink rate of the heat shrinkable film is 10% or more in the horizontal direction and 20% or more in the vertical direction. ~ 3. A shrink-wrap body according to any one of the above.
5). Using heat-shrinkable films with different heat sealing temperatures on both surface layers, the contents are stored in a cylindrical film with the outermost layer having a higher heat sealing temperature than the innermost layer placed outside the package. The cylindrical film opening is evacuated with a fold inward from at least one side surface of both ends, and sealed and sealed at a temperature suitable for the innermost layer seal. Shrinkage characterized in that after forming the package, the film on the lower surface side of the preliminary package is first thermally contracted, the sealing seal part of the opening is drawn downward, and then the film on the upper surface side is thermally contracted. Packaging method .

  The most different point of the present invention from the prior art is that a gusset-shaped fold is first provided in the hermetic seal portion, and thus the protrusions after heat shrinkage, which has been a problem in the past, are not generated. The package has a beautiful appearance, and damage such as pinholes caused by protrusions is greatly improved. In particular, among heat-shrinkable films having gas barrier properties, films with a polyamide-based resin layer arranged to enhance pinhole resistance are generally low in heat-shrinkability, but these films have poor heat-shrinkability. Can be packaged without any protrusions. Furthermore, by using a heat-shrinkable film having different heat seal temperatures and disposing a surface layer having a high heat seal temperature so as to be outside the package, the end of the hermetic seal portion in the gusset folding portion. It becomes possible to provide a knob part in the part, and thereby easy opening property can be imparted.

  A preferred package of the present invention will be described with reference to FIGS. First, FIGS. 1 to 3 show a case of a conventional packaging method using a corner cutting tray. FIG. 1 shows a corner cutting tray 2 containing contents (the contents are omitted in the figure. Hereinafter, similarly) The contents are omitted in all the drawings.) Is stored in a cylindrical film formed by the vertical seal 4 made of the heat-shrinkable film 1, and this is degassed and the opening is hermetically sealed. It is a package. FIG. 2 is a plan view of this. FIG. 3 is obtained by first shrinking the film on the lower side of the tray of this pre-packed body and drawing the sealing seal part 3 of the opening downward, and then heating the whole with hot air to shrink the film on the upper side. FIG. Protrusions 5 are generated in the shrink wrapping body, and the cosmetic appearance as a product is deteriorated in appearance, and there is a problem such as damage to another adjacent wrapping body at the tip of the protrusion. There was a problem of misalignment.

  Next, the preferable form of this invention is demonstrated. FIG. 4 to FIG. 6 show examples of the present invention using the same corner-cutting tray and heat-shrinkable films having different heat sealing temperatures of both surface layers. FIG. 4 shows a corner tray 2 in which contents are placed in a cylindrical film formed by a vertical seal 4 made of a heat-shrinkable film 1 and having a surface layer having a high heat seal temperature arranged outside the package. Is a pre-packed body having a gusset portion 6 that is degassed and hermetically sealed with both opening portions of the tubular film provided with a fold portion inward from the side surface. The folded portion is not necessarily provided on both side surfaces, and may be provided only on one side surface. In the case of both side surfaces, a difference may be provided in the degree of the left and right folded portions. FIG. 5 is a plan view of this. Here, the vertical seal has a palm-pasting method in which the inner surfaces of the heat-shrinkable film end portions are opposed to each other, or an envelope-pasting method in which the heat-shrinkable film end portions are stacked and the inner surface and the outer surface are fused, The film may be selected as appropriate in consideration of the heat seal characteristics of both surface layers of the film, but a palm-pasting method is preferred from the viewpoint of sealing integrity.

At the stage of obtaining this pre-packed body, a knob portion 8 whose tip is divided into a Y-shape is formed on the gusset-shaped hermetic seal portion. This is because the sealing of the package is performed under a temperature condition suitable for sealing the innermost layer of the film, and naturally the outermost layers having a high sealing temperature are difficult to fuse together, so that a knob suitable for easy opening can be formed. However, the greater the difference between the sealing temperatures of the two surface layers, the easier this knob portion can be formed.
Here, the heat seal temperature difference between the two surface layers is preferably a heat seal index temperature difference of the main resin constituting each surface layer of 10 ° C. or more, more preferably 20 ° C. or more, more preferably 30 ° C. or more. is there. What is necessary is just to be packaged by disposing the surface having the high heat seal index temperature as the outermost layer. In the present invention, the heat seal index temperature is a remelting peak temperature measured at a heating rate of 10 ° C./min by a differential scanning calorimeter (DSC) in the case of a crystalline resin, and in the case of an amorphous resin. Means the temperature of glass transition temperature + 30 ° C. measured at a rate of temperature increase of 10 ° C./min according to JIS-K7121 by the DSC method.

In addition, as an auxiliary means for facilitating the formation of the knob portion, it is possible to crosslink the outermost layer to lower the thermal fluidity, or to add a coating or additive for inhibiting fusion, It is also possible to add an adhesive or the like for promoting the fusion to the innermost layer.
The knob at the end of the hermetic seal portion does not need to be formed at both ends, and may be at one end. At the stage of obtaining this pre-packed body, the knob part divided into Y shapes may not be seen in some cases, but the knob part is formed after the completion of the next heat shrinkage or the knob part is still formed. If not, a Y-shaped knob can be formed with a slight force as will be described later.

The hermetic seal of the present invention, including the vertical seal, is based on heat seal, but heat sealers include hot plate sealers, impulse sealers, ultrasonic sealers, band sealers, hot air sealers, high frequency sealers, frame sealers, etc. Just choose. The internal deaeration is performed before all the openings are hermetically sealed, and is intended to prevent the package from being swollen by the internal gas when the film is thermally contracted. is there. Then, by performing this deaeration, a packaging body in which the film is in close contact with the package body can be obtained without providing the deaeration holes used in the conventional shrink wrapping.
As a degassing method, just before forming the final hermetic seal portion, for example, a method of pressing the object to be packed with a flexible material such as sponge to extrude the gas inside, and surroundings such as suction by a vacuum pump There is a method of deaeration using the pressure difference between the two, but it may be selected as appropriate.

FIG. 6 shows an embodiment of the present invention obtained by first shrinking the film on the lower side of the tray of this pre-packed body and drawing the sealing seal part 3 of the opening downward, and then shrinking the film on the upper side. It is an example of a shrink wrap.
As described above, the obtained package may not be formed with a knob part at first glance. However, if the finger is inserted into the gusset folding part at the end of the sealing seal part, the Y-shaped part can be easily obtained. A knob is formed. There are various ways to use the knobs at the time of opening, but the Y-shaped knobs at the ends are gripped with both hands and opened by opening them up or down, or they are similarly pinched and twisted to form a sealed seal It can be opened easily by opening a tear, for example, but a notch such as a notch may be provided as appropriate.

As a means for heat shrinking, hot air is preferable, but hot water, heating steam, infrared rays, or the like can be appropriately used. Moreover, although shrinking of the film on the upper surface side may be performed by heating only from above the tray, it may be performed by applying hot air or the like from all directions. Here, the film on the lower surface of the tray is first thermally contracted, and the purpose of attracting the hermetic seal portion 3 of the opening downward is that when the film on the upper surface side of the tray to be subsequently contracted is thermally contracted, This is to prevent the appearance of the sheet from rising to the upper surface of the package. Therefore, when the film on the lower surface of the tray of the preliminary package is first thermally shrunk, this means that the hermetic seal portion is not located on the upper surface of the package. And most of the hermetic seal part in the shrink-wrapped body finally obtained by shrinking the film on the upper surface side of the tray to be performed next, preferably 80% or more of the lateral dimension of the hermetic seal part, more preferably 90%. % Or more, more preferably all of the lateral dimensions are located on the side or bottom of the final package. In the obtained shrink package, the protrusions 5 produced by the conventional packaging method are not seen, and the product has a favorable merchandise in terms of appearance, and to the adjacent package that the tip of the conventional protrusions 5 has brought about Damages such as pinholes are greatly improved.
Similarly, FIG. 7 to FIG. 9 show examples of the shrink wrapping body of the present invention when a bowl-shaped container is used, and FIG. 10 shows the pre-packaging body with the lidded container being heat shrunk. The example of the shrink wrapping body of the present invention obtained in this way is shown.

  In the method of the present invention, when forming a pre-packaging body having a gusset portion 6 by sealing and sealing both openings of the tubular film in a state where a fold portion is provided inward from the side surface, for example, FIG. 5. It is preferable that the hermetic seal portion lateral dimension Ls of the preliminary packaging body having the gusset shape shown in FIG. 8 is equal to or less than the maximum projected lateral dimension Li viewed from the upper surface of the package. The measurement of Li is carried out by placing the object to be packaged in contact with each plate surface on a corner forming body composed of three flat plates having a right angle relative to the object to be packaged. A simple method is to measure the distance between two angulation bodies by sandwiching the object to be packaged with another angulation body. The hermetic seal portion tends to bend slightly due to heat shrinkage of the film. The linear distance at both ends of the hermetic seal portion is measured and this is defined as Ls.

As a result, the package finally obtained after heat shrinkage uses a film with poor heat shrinkability, or even if the deaeration just before sealing the opening is slightly insufficient, the hermetic seal part becomes a problem. The corner portion or the tip portion of the container does not protrude beyond the side surface of the container parallel to the vertical seal, and the effect of improving the adverse effect on the adjacent package is further ensured.
Next, the container referred to in the present invention includes a tray or a container composed of a lid and a main body, and also includes a container having a hinge and a main body called a food pack integrated. Furthermore, the above may have an inner pan located inside the tray or between the lid and the main body. When the container is used for gas replacement packaging, an opening is provided in a state in which the lid or the main body or the lid and the main body are fitted so that gas replacement can be easily performed, particularly in the case of a container with a lid. Ordinarily, it may be formed into a shape that can accommodate a small bag type oxygen scavenger. The material of these containers is not particularly limited, but is used alone or in combination from known resins, metals, paper, wood (including pulp), etc., but from the viewpoint of transparency and variety of shapes. Known resins are preferred because of their excellent moldability.

  The heat-shrinkable film used in the present invention preferably has a heat shrinkage rate of 10% or more in the horizontal direction and 20% or more in the vertical direction. If the thermal contraction rate in the transverse direction is 10% or more, the film and the packaged material after the thermal contraction have sufficient adhesion, and the film is less likely to be damaged or wrinkled. On the other hand, if the thermal shrinkage rate in the vertical direction is 20% or more, the hermetic seal portion at the open ends is less likely to cause irregular shrinkage depending on the degree of folding for forming the gusset. It is preferable that both the horizontal direction and the vertical direction satisfy the heat shrinkage rate at the same time. There is no particular limitation on the upper limit of the heat shrinkage rate, but in order to avoid container deformation during heat shrinkage, the horizontal direction and the vertical direction. It is preferable that both the thermal shrinkage ratios are 90% or less.

Furthermore, the preferable heat shrinkage rate for effectively using the hermetic seal portion as a knob to effectively exhibit the easy-opening property is 10% to 70% in the horizontal direction and 10% to 70% in the vertical direction, depending on the degree of folding. 20 to 70%, more preferably 10 to 60% in the horizontal direction and 20 to 60% in the vertical direction, and still more preferably 10 to 50% in the horizontal direction and 20 to 50% in the vertical direction.
The heat shrinkage rate in the present invention refers to a 100 mm square film sample placed in an air oven type thermostat set at a predetermined temperature, treated for 10 minutes in a state where it can be freely heat shrunk, and then laterally and longitudinally. The heat shrinkage dimension is determined and expressed as a percentage of the value divided by the original dimension. The heat shrink temperature may be measured at an arbitrary temperature between 80 ° C. and 160 ° C. in consideration of the heat shrink temperature conditions during actual packaging.

  The resin constituting the heat-shrinkable film is not particularly limited as long as it contains a thermoplastic resin that can be heat-sealed. For example, high-pressure method low-density polyethylene, high-density polyethylene, ethylene-α olefin copolymer ( Linear low-density polyethylene, ultra-low-density polyethylene, and soft resins having a crystallinity of 30% or less by the X-ray method other than those described on the left), cyclic polyolefins, polypropylene-based resins (homo and comonomers such as ethylene and butene) A copolymer with a kind of α-olefin), poly-4-methylpentene resin, crystalline 1,2 polybutadiene, a soft polymer comprising an α-olefin copolymer different from the ethylene-α-olefin copolymer, ethylene-acetic acid Vinyl copolymer, ethylene-aliphatic unsaturated carboxylic acid copolymer, ethylene-aliphatic unsaturated carbon Bonic acid ester copolymers, block copolymers of vinyl aromatic hydrocarbons and conjugated dienes, derivatives such as those obtained by hydrogenating at least part of their double bonds, styrenic elastomers other than those on the left, ethylene-vinyl alcohol Copolymer (hereinafter referred to as EVOH), polyamide resin, polyester resin, biodegradable resin (polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate terephthalate, polytetra Methylene adipate terephthalate, polybutylene adipate terephthalate, etc.), and modified polymers thereof (acid-modified, ionized, etc.), one selected from these, or a blend resin obtained by mixing two or more resins Mainly using these resins (5 A blended resin in which a resin other than the above is mixed can be used.

Although the heat-shrinkable film used in the present invention has a multilayer structure, a film obtained by coextrusion molding is preferred, but it may be laminated and the thickness is not particularly limited, but preferably 5 to 100 μm. Preferably it is 10-80 micrometers, More preferably, it is 10-50 micrometers.
In addition, what is necessary is just to select suitably resin used for both surface layers including the example of resin which comprises said heat shrinkable film.
In addition, the heat-shrinkable film used in the present invention may be subjected to a crosslinking treatment, such as an antifogging agent, a lubricant, a plasticizer, an antioxidant, an ultraviolet absorber, an oxygen absorber, an antibacterial agent, a colorant, and various surfactants. An agent, an antiblocking agent, an inorganic filler, a tackifier, and the like can be included, and corona treatment, plasma treatment, and various coating treatments can be performed.

The most preferred form according to the present invention is the case where a heat-shrinkable film having gas barrier properties is used, and since many gas barrier films usually have poor heat-shrinkability, the packaging method of the present invention is particularly useful. It is. When the heat-shrinkable film of the present invention is a gas barrier film, the barrier property is preferably about 30,000 ml / (m ² · day · Mpa) or less, preferably at a value of oxygen permeability at 23 ° C. and 65% RH. by weight, more preferably ^{20,000ml / (m 2 · day ·} Mpa) or less, more preferably ^{10,000ml / (m 2 · day ·} Mpa) or less, even more preferably ^{5000ml / (m 2 · day ·} Mpa ) In addition, oxygen permeability is measured by the method of ASTM-D-3985.

The gas barrier layer may be a resin layer containing at least one of EVOH, polyamide resin, thermoplastic polyester resin, vinylidene chloride resin, polyacrylonitrile resin, polyglycolic acid resin, etc., vinylidene chloride resin, It may include a coating layer made of polyvinyl alcohol, EVOH, acrylic resin, and those obtained by dispersing an inorganic filler in these resins. Furthermore, in the case of packaging contents that dislike oxygen, a multilayer structure in which an oxygen absorbing layer is arranged is preferable.
In the present invention, the heat-shrinkable film having gas barrier properties is mainly used for gas replacement packaging, and the gases used include nitrogen, oxygen, carbon dioxide, argon, xenon, krypton, alcohols and allyl mustard oil, etc. These are used alone or in combination depending on the purpose. As a gas replacement method in the present invention, a gas flash method is generally used, but for the purpose of improving the gas replacement rate, it is also possible to perform gas replacement by combining a pressure reduction process with an appropriate vacuum degree and a gas flash.

Example 1
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 25 μm. Packaging was performed using a film. The heat seal index temperature difference of this film was 75 ° C. The ethylene-α-olefin copolymer layer contained 2 wt% of an antifogging agent mainly composed of a nonionic surfactant. The oxygen permeability of this film was 200 ml / (m ² · day · Mpa), and the heat shrinkage at 120 ° C. was 22% vertical and 24% horizontal.
As a package, a container with a lid containing about 100 g of clay as a dummy was used as the contents. The container with a lid has an outer dimension of 130 mm (length) x 110 mm (width) x 38 mm (height) (height of the container body is 21 mm), and a gas replacement hole is attached to the lid. Each corner has a rounded shape with a radius of curvature of about 38 mm and an arc length of 53 mm. The container is made of polystyrene and the body is made of polypropylene filled with an inorganic filler.

  Packaging was continuously performed at a rate of 30 packs per minute in a pillow shrink packaging machine capable of gas replacement by a gas flash system. Push the gusset fold-in bar in the cylindrical film that has been replaced with the atmosphere of nitrogen / carbon dioxide = 70/30 (volume ratio) by gas flush, and place the cylindrical film in the immediate vicinity of the end sealer. In the state where the folding part is provided inside the cylindrical film, the front is hermetically sealed first, then the cylindrical film moves forward, and similarly, the cylindrical inner part starts from the other opening end where the folding part is provided. After removing the excess gas with a sponge and degassing, the open end was hermetically sealed to form a pre-packed body having a gusset shape continuously. At this time, the value of Ls / Li was 88/110 = 0.80.

These preliminary packaging bodies were continuously blown with hot air from the bottom to shrink the film on the bottom and side surfaces of the container, and then further heated with air from the top of the preliminary packaging body to obtain a tightly finished packaging body. The resulting package had a clean appearance with no film projections remaining at the container corners. In addition, since the outer surface of the film forming the tube is a polyamide-based resin, the sealing seal end surface is Y-shaped to form a knob, and can be easily opened by pinching the knob with both hands and pulling. there were.
In addition, 4 pieces of the resulting packaging are stacked in 2 stages, a total of 8 boxes are packed in cardboard, and after applying vibration in accordance with the JIS Z0232 packaging cargo-vibration test method, packaging is performed. The body was taken out and the presence or absence of a pinhole was investigated by "Ageless seal check" manufactured by Mitsubishi Gas Chemical Co., Ltd. The vibration test conditions were carried out with a cardboard box fixed, acceleration of 0.75 G, frequency of 5 to 50 Hz, 40 minutes in the vertical direction, 20 minutes in the horizontal and horizontal directions, and 20 minutes in the horizontal and vertical directions for a total of 80 minutes.
As a result, no pinhole was observed in the package.

(Comparative Example 1)
A shrink-wrap package was obtained in the same manner as in Example 1 except that the same film as in Example 1 was used for packaging without forming a folded portion inside the tubular film. At this time, Ls / Li of the preliminary package was 1.09. The resulting package had clear protrusions at the corners, was inferior in beauty, and the tip of one protrusion was hard and sharp. When this package was subjected to a vibration test in the same manner as in Example 1 and the occurrence of pinholes was examined, 3 out of 8 packages had pinholes that were thought to be due to the tip of the protrusion. Admitted. In addition, it is extremely difficult to open the package by hand, and it is necessary to use a tool such as scissors, and the package has a problem in easy-openability.

(Example 2)
In the same manner as in Example 1, the layer constitution is polypropylene resin / adhesive resin / polyamide resin / amorphous polyester / EVOH / adhesive resin / ethylene-α olefin copolymer (innermost layer heat seal layer). Packaging was performed using a film having a thickness ratio (%) of each layer of 10/5/20/20/10/5/30 and a thickness of 25 μm. The heat seal index temperature difference of this film was 22 ° C. The ethylene-α-olefin copolymer layer contains 2 wt% of an antifogging agent mainly composed of a nonionic surfactant with respect to each layer, and the oxygen permeability of the film is 150 ml / (m ² · day · Mpa ), The heat shrinkage at 120 ° C. was 35% vertical and 33% horizontal. Moreover, Ls / Li of the preliminary package was 0.73.
The resulting package had a tight finish and had a beautiful appearance with no film projections remaining at the corners of the container. Further, when pinhole resistance was investigated by applying vibration under the same conditions as in Example 1, no pinholes were observed in the package. In addition, although the sealed seal part is apparently finished in a linear shape at first glance, it is possible to easily form a knob with the seal end part being Y-shaped by pulling the folded part with a fingertip. When the knob was pulled to twist like the case 1, the film was easily torn and could be opened.

(Comparative Example 2)
The layer structure is ethylene-α olefin copolymer / adhesive resin / EVOH / adhesive resin / ethylene-α olefin copolymer, and the thickness ratio (%) of each layer is 38/7/10/7/38, thickness. Was packaged in the same manner as in Example 1 using a 25 μm film. The ethylene-α-olefin copolymer of both surface layers used the same resin, and each layer contained 1 wt% of an antifogging agent mainly composed of a nonionic surfactant. The oxygen permeability of this film was 220 ml / (m ² · day · Mpa), and the heat shrinkage at 100 ° C. was 40% vertical and 34% horizontal. The Ls / Li of the preliminary package in this packaging was 0.82. The resulting package had no film protrusions at the corner of the container and had a tight and beautiful finish, but was difficult to open by hand and had a problem with easy opening.

  The present invention can be suitably used in the field of shrink packaging such as food packaging.

The perspective view which shows the preliminary | backup packaging body before heat shrink after completion of the sealing seal | sticker by the conventional packaging method using a corner cutting tray. The top view of the preliminary packaging body shown in FIG. The top view which shows the package obtained by carrying out the heat shrink of the preliminary packaging body shown in FIG. The perspective view which shows the example of the preliminary packing body of the gusset shape of this invention which uses a corner cutting tray. FIG. 5 is a plan view of the preliminary package shown in FIG. 4. The perspective view which shows the example of the package of this invention which has a knob part in the sealing seal | sticker part obtained by heat-shrinking the preliminary package shown in FIG. The perspective view which shows the example of the preliminary packing body of the gusset shape of this invention which uses a bowl-shaped container. The top view of the preliminary packaging body shown in FIG. The perspective view which shows the example of the package of this invention which has a knob part in the sealing seal | sticker part obtained by heat-shrinking the preliminary package shown in FIG. The perspective view which shows the example of the package of this invention which used the container with a lid | cover as a to-be packaged object, and has a knob part in the sealing seal part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film 2 Tray or container main body 3 Opening part sealing seal part 4 Heat seal part (vertical seal) for forming a cylindrical film
5 Projection 6 Gusset 7 Lid 8 Y-shaped knob Li Maximum projected horizontal dimension Ls seen from the top of the package

Claims (5)

A shrink-wrapped package formed by packaging heat-shrinkable films having different heat-seal temperatures on both surface layers, and a cylindrical heat-shrinkable film having an outermost layer having a higher heat-seal temperature than the innermost layer. It has a gusset-shaped hermetic seal part in which at least one of both ends of the tubular film is folded inward from the side surface, and the tip of the hermetic seal part is outward. Shrink wrapping body characterized by being divided into a Y shape toward The shrink-wrap package according to claim 1, wherein the hermetically sealed portion is located below. The shrink-wrap package according to claim 1 or 2 , wherein the heat-shrinkable film has a gas barrier property. The shrinkable packaging body according to any one of claims 1 to 3 , wherein the heat shrinkage rate of the heat-shrinkable film is 10% or more in the transverse direction and 20% or more in the longitudinal direction. Using heat-shrinkable films with different heat sealing temperatures on both surface layers, the contents are stored in a cylindrical film with the outermost layer having a higher heat sealing temperature than the innermost layer placed outside the package. The cylindrical film opening is evacuated with a fold inward from at least one side surface of both ends, and sealed and sealed at a temperature suitable for the innermost layer seal. Shrinkage characterized in that after forming the package, the film on the lower surface side of the preliminary package is first thermally contracted, the sealing seal part of the opening is drawn downward, and then the film on the upper surface side is thermally contracted. Packaging method .

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