Manufacturing method of packaged goods

Abstract

To provide a manufacturing method for a packaging that suppresses a heat-shrinkable film having gas barrier properties from wrinkling even when the film is used for wrapping.SOLUTION: There is provided a manufacturing method comprising a longitudinal sealing process, a lateral sealing process and a heat shrinking process. A heat-shrinkable film 2 comprises a gas barrier layer. If a tensile elastic modulus in an MD direction of the film is Em and a tensile elastic modulus in a TD direction is Et, Em and Et are each 650 MPa or less and satisfy Em / Et≥1.1, and if a heat shrinkage in the MD direction is Sm and a heat shrinkage in the TD direction is St when the film is heated at 100°C for 30 minutes, Em and Et are each 25% or more and satisfy Sm / St≥1.1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a packaged product obtained by applying wrap packaging to a packaged product. [Background technology]

[0002] Patent Document 1 discloses a method for producing a packaged product by placing the packaged items in a deep-bottomed tray, adding an oxygen scavenger to the tray together with the packaged items, and covering the opening of the tray with a plastic film having gas barrier properties. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-301744 Summary of the Invention [Problem to be solved by the invention]

[0004] Heat-shrinkable films having gas barrier properties have lower flexibility than general heat-shrinkable films not having gas barrier properties, and wrinkles tend to form in the films during wrapping.

[0005] The present invention has been made in consideration of the above circumstances, and provides a method for producing a packaged product in which the occurrence of wrinkles in the film is suppressed even when the product is wrapped using a heat-shrinkable film having gas barrier properties. [Means for solving the problem]

[0006] According to the present invention, a method for producing a packaged product includes a vertical sealing step, a horizontal sealing step, and a heat shrinking step. In the vertical sealing step, a cylindrical body is formed by welding opposing portions of the film at an overlapping portion formed by overlapping both ends of the film in the width direction, and a horizontal sealing step forms a package in which the packaged product is sealed within the film by forming horizontal seal portions on the cylindrical body at positions adjacent to the front and rear of the packaged product while the packaged product is placed within the cylindrical body. wherein in the heat shrinking step, the film surrounding the package is shrunk, the film having a gas barrier layer, and where Em is a tensile modulus of elasticity of the film in the MD direction and Et is a tensile modulus of elasticity of the film in the TD direction, Em and Et are each 650 MPa or less and Em / Et≧1.1, and where Sm is a heat shrinkage rate in the MD direction when the film is heated at 100° C. for 30 minutes and St is a heat shrinkage rate in the TD direction, Sm and St are each 25% or more and Sm / St≧1.1.

[0007] As a result of extensive research, the inventors have found that when the tensile modulus and heat shrinkage rate satisfy the above conditions, wrinkles are less likely to occur in the film even when wrapped using a heat-shrinkable film with gas barrier properties, and have thus completed the present invention. [Brief description of the drawings]

[0008] [Figure 1] 1A to 1C are perspective views showing a manufacturing process of a package 1 according to an embodiment of the present invention. [Diagram 2] FIG. 2A is a perspective view of a package 9, and FIG. 2B is a perspective view of a package 1. As shown in FIG. [Diagram 3] The layer structure of film 2 is shown. [Figure 4] 2B, showing a state in which the transverse seal portion 8 protrudes from the side surface 1a of the package 1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described. Various features shown in the following embodiments can be combined with each other. Also, each feature can be an invention independently.

[0010] 1. Manufacturing method of packaged product 1 The manufacturing method of the packaged product 1 according to one embodiment of the present invention includes a vertical sealing step, a horizontal sealing step, and a heat shrinking step. Each step will be described in detail below with reference to Fig. 1 and Fig. 2. Each step can be performed using an automatic packaging machine using a horizontal pillow method.

[0011] <Vertical sealing process> In the vertical sealing step, opposite ends of the film 2 in the width direction are overlapped to form an overlapping portion 4, at which opposing portions of the film 2 are welded to form a vertical seal portion 5, thereby forming a cylinder 6.

[0012] The film 2 is a heat-shrinkable film having gas barrier properties, and details thereof will be described in "2. Details of Film 2." The film 2 is supplied by being unwound from a film roll 7 around which a long film is wound. The traveling direction of the film 2 unwound from the film roll 7 is the MD direction, and the width direction of the film roll 7 is the TD direction of the film 2. In other words, the MD direction is the longitudinal direction of the vertical seal portion 5, and the TD direction is the longitudinal direction of the horizontal seal portion 8 described below.

[0013] The vertical seal portion 5 can be continuously formed, for example, by sandwiching the overlapping portion 4 between a pair of sealing rollers 10 rotating in opposite directions and welding opposing portions of the film 2 while feeding the film 2 downstream.

[0014] <Horizontal sealing process> In the horizontal sealing process, the packaged product 3 is placed inside the cylindrical body 6, and horizontal seal portions 8 are formed in the cylindrical body 6 at positions adjacent to the front and back of the packaged product 3, thereby forming a package 9 in which the packaged product 3 is sealed within the film 2.

[0015] In one example, the packaged product 3 is a container in which contents such as food are placed. The packaged product 3 may be inserted into the cylindrical body 6 after the cylindrical body 6 is formed, or the cylindrical body 6 may be formed so as to surround the packaged product 3. The packaged product 3 is preferably arranged so that the longitudinal direction of the packaged product 3 is parallel to the longitudinal direction of the vertical seal portion 5.

[0016] In one example, the planar shape of the packaged product 3 is a rectangle that may have rounded corners. The length of the long side of the packaged product 3 is, for example, 120 to 250 mm, specifically, for example, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, or 250 mm, or may be within a range between any two of the numerical values ​​exemplified here. The length of the short side of the packaged product 3 is, for example, 80 to 200 mm, specifically, for example, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 mm, or may be within a range between any two of the numerical values ​​exemplified here. The radius of curvature of the corner with the smallest radius of curvature is, for example, 5 to 50 mm, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 mm, and may be within a range between any two of the numerical values ​​exemplified here. The height of the packaged product 3 is, for example, 10 to 50 mm, specifically, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0017] The transverse seal portion 8 can be formed, for example, by sandwiching the cylinder 6 with a pair of seal bars 11 and welding opposing portions of the film 2. When forming the transverse seal portion 8 or after forming the transverse seal portion 8, the transverse seal portion 8 can be divided to form an upstream transverse seal portion 8a of the downstream package 9 and a downstream transverse seal portion 8b of the upstream cylinder 6. The transverse seal portion 8 can be divided using a cutter built into the seal bar 11, or using a cutter arranged downstream of the seal bar.

[0018] <Heat shrinking process> The heat shrink process involves heat shrinking the film 2 surrounding the package 9. This process can be accomplished by moving the package 9 through a heat shrink tunnel.

[0019] Since the film 2 is heat-shrinkable, by heat-treating the packaging body 9 to heat-shrink the film 2, a packaged product 1 is obtained in which the film 2 is in close contact with the packaged product 3. The heat treatment can be performed at, for example, 80 to 120° C. The heat treatment time is, for example, 5 to 30 seconds.

[0020] 2. Details of Film 2 3, the film 2 may be a heat-shrinkable film having a gas barrier layer 2b, and preferably has an inner layer 2a, a gas barrier layer 2b, and an outer layer 2c, in that order from the inner surface side facing the packaged product 3. If the adhesion between the inner layer 2a or the outer layer 2c and the gas barrier layer 2b is not good, it is preferable to provide an adhesive layer 2d between the inner layer 2a or the outer layer 2c and the gas barrier layer 2b.

[0021] The inner layer 2a is a layer to be heat sealed, and is preferably made of a resin with excellent heat sealability such as polyolefin (e.g., polyethylene, polypropylene). The outer layer 2c is a layer for preventing the gas barrier layer 2b from absorbing moisture and decreasing its performance, and can be made of a resin with excellent moisture barrier properties such as polyolefin (e.g., polyethylene, polypropylene).

[0022] The adhesive layer 2d is made of an adhesive resin. Examples of the adhesive resin include acid-modified polyolefin resins (e.g., maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene). By providing the adhesive layer 2d, the adhesion between the layers adjacent to the adhesive layer 2d is improved.

[0023] The gas barrier layer 2b is made of a gas barrier resin. In this specification, the gas barrier resin is defined as a resin having an oxygen permeability of 50 cc / (m2) in a film having a thickness of 20 μm under an environment of 20° C. and 65% RH. 2The oxygen permeability is, for example, 0 to 49 cc / (m 2 ·24 hours ·atm), specifically, for example, 0.01, 0.1, 0.2, 0.5, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 49cc / (m 2 24 hours atm), and may be within a range between any two of the values ​​given as examples here, or any of the values ​​below.

[0024] The gas barrier resin may be composed of only a resin having high gas barrier properties such as EVOH or polyamide, or may be a mixed resin of the above resin and another resin. An example of the other resin is an adhesive resin. By blending an adhesive resin in the gas barrier layer, the adhesive layer 2d between the gas barrier layer and the adjacent layer can be omitted, and the number of layers constituting the film 2 can be reduced.

[0025] The thickness of the film 2 is, for example, 5 to 60 μm, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 μm, and may be within a range between any two of the numerical values ​​exemplified here.

[0026] Assuming that the tensile modulus of elasticity of film 2 in the MD direction is Em and the tensile modulus of elasticity in the TD direction is Et, Em and Et are each 650 MPa or less and Em / Et≧1.1, and assum- ing that the heat shrinkage rate of the film when heated at 100°C for 30 minutes is Sm and the heat shrinkage rate of the film in the TD direction is St, Sm and St are each 25% or more and Sm / St≧1.1.

[0027] As shown in the examples described later, it has been found that when the tensile modulus and heat shrinkage rate satisfy the above conditions, wrinkles are less likely to occur in the film even when wrapped using a heat-shrinkable film having gas barrier properties.

[0028] Furthermore, when the tensile modulus of elasticity and the heat shrinkage rate do not satisfy the above conditions, the horizontal seal portion 8 tends to protrude from the side surface 1a of the packaged product 1 as shown in Fig. 4, but when the tensile modulus of elasticity and the heat shrinkage rate satisfy the above conditions, the horizontal seal portion 8 tends to be folded along the side surface 1a of the packaged product 1 as shown in Fig. 2B. The state in Fig. 2B looks better than the state in Fig. 4, and the horizontal seal portion 8 is less susceptible to impact during transportation, etc., so that the occurrence of pinholes due to impact on the horizontal seal portion 8 is suppressed.

[0029] In this specification, the tensile modulus can be measured in an atmosphere of 23° C. and 50% RH in accordance with ASTM-D-882, and the heat shrinkage can be measured in accordance with ASTM-D2732.

[0030] Em and Et are each, for example, 250 to 650 MPa, specifically, for example, 250, 300, 350, 400, 450, 500, 550, 600, and 650 MPa, and may be within a range between any two of the numerical values ​​exemplified here. Em / Et is, for example, 1.1 to 2.0, specifically, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0, and may be within a range between any two of the numerical values ​​exemplified here.

[0031] Each of Sm and St is, for example, 25 to 40%, specifically, for example, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40%, and may be within a range between any two of the numerical values ​​exemplified here. Sm / St is, for example, 1.1 to 2.0, specifically, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0, and may be within a range between any two of the numerical values ​​exemplified here.

[0032] The heat shrinkage rate of the film 2 can be adjusted to a predetermined range mainly by changing the thickness configuration and stretching ratio of both surface layers and the intermediate layer, the blow-up ratio (bubble diameter / die diameter) when forming the film 2 by inflation, and temperature conditions such as the stretching temperature and cooling conditions. For example, when the heat shrinkage rate is smaller than the desired value, the stretching rate in the longitudinal direction and / or transverse direction may be increased, or the cooling efficiency may be appropriately adjusted, such as by increasing the amount of cooling blower in outer surface cooling or by using inner surface cooling in combination, so as to increase the heat shrinkage distortion at a lower temperature. Conversely, when the heat shrinkage rate is larger than the desired value, the stretching rate in the longitudinal direction and / or transverse direction may be decreased, or the cooling efficiency may be appropriately adjusted, such as by decreasing the amount of cooling blower in outer surface cooling or by weakening inner surface cooling, so as to decrease the heat shrinkage distortion at a lower temperature. Similarly, the tensile modulus of the film 2 can be adjusted by changing the thickness configuration and stretching ratio of both surface layers and the intermediate layer. EXAMPLES

[0033] 1. Example 1 A container (170 mm x 109 mm x 17 mm) was manufactured by vacuum forming a non-foamed resin sheet (thickness 0.35 mm) made of APET to which no antiblocking agent was added.

[0034] Next, a gas-barrier heat-shrinkable film (having a gas-barrier layer of EVOH sandwiched between polyethylene layers with an adhesive layer between them) having the physical properties shown in Table 1 was formed into a cylindrical shape using a horizontal pillow type automatic packaging machine, and a container filled with a content was inserted while spraying the gas to be filled into the cylindrical shape, and both ends of the film in the width direction were overlapped and heat-sealed to form a vertical seal, and the front and back of the container were heat-sealed while discharging excess gas to minimize the space around the container to form a horizontal seal, thereby obtaining a gas-filled sealed envelope. The resulting envelope was introduced into a heat-shrink tunnel, and the film was heat-shrunk to obtain the package of Example 1.

[0035] 2. Example 2 and Comparative Examples 1-2 A packaged product was obtained in the same manner as in Example 1, except that a film having the physical properties shown in Table 1 was used.

[0036] 3. Evaluation Comparing the packages of Examples 1 and 2 with those of Comparative Examples 1 and 2, there were fewer wrinkles in the film of Examples 1 and 2. In Comparative Example 1, the transverse seal portion 8 protruded from the side surface 1a of the package 1, but in Examples 1 and 2, the transverse seal portion 8 did not protrude from the side surface 1a of the package 1.

[0037] [Table 1] [Explanation of symbols]

[0038] 1:Packaged goods 1a: Side 2: Film 2a :Inner layer 2b: Gas barrier layer 2c: outer layer 2d: Adhesive layer 3: Packaged product 4: Joint 5: Vertical seal section 6: Cylinder 7: Film roll 8: Horizontal seal section 8a: Upstream horizontal seal section 8b: Downstream horizontal seal section 9: Packaging 10: Seal roller 11: Seal bar

Claims

[Claim 1] A method for manufacturing a packaged product, comprising the steps of: The method includes a vertical sealing process, a horizontal sealing process, and a heat shrinking process. In the vertical sealing step, opposite ends of the film in the width direction are overlapped to form an overlapping portion, and opposing portions of the film are welded to form a vertical seal portion to form a cylindrical body; In the transverse sealing step, a package is formed in which the packaged product is sealed within the film by forming transverse seal portions on the cylindrical body at positions adjacent to the front and rear of the packaged product while the packaged product is placed in the cylindrical body, In the heat shrinking step, the film surrounding the package is shrunk, The film comprises a gas barrier layer, The tensile modulus of the film in the MD direction is Em and the tensile modulus of the film in the TD direction is Et, where Em and Et are each 650 MPa or less, and Em / Et is 1.2 or more; wherein when the film is heated at 100° C. for 30 minutes, the heat shrinkage in the MD direction is Sm and the heat shrinkage in the TD direction is St, Sm and St are each 25% or more and Sm / St≧1.1.

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