JP7524431B1 - Packaging laminate film - Google Patents

Abstract

The present invention provides a laminated film for packaging that enables high-speed operation of a filling and packaging machine and improves the productivity of packaging bags.
[Solution] A packaging laminate film used in a filling and packaging machine equipped with a heat sealing means, comprising at least a base layer and a sealant layer, the sealant layer having at least a two-layer structure, and at least one of the sealant layers other than the outermost sealant layer containing an inorganic filler.
[Selected Figure] Figure 1

Description

This invention relates to a laminated packaging film used in a filling and packaging machine equipped with a heat sealing means, and in particular to a laminated packaging film that has excellent heat sealing properties and allows for high-speed filling.

Vertical filling and packaging machines such as those described in Patent Document 1 have been known as devices for continuously manufacturing packages by forming a long, flexible laminated film into a bag shape and filling and packaging liquids such as food and beverages, seasonings, medicines, cosmetics, and other liquids, viscous substances, or powders, granules, and other packaged items. This vertical filling and packaging machine is equipped with a pair of vertical sealing rolls that fold a strip-shaped laminated film in two at the center position in the width direction and continuously seal the overlapping side edges in the running direction of the laminated film to form a cylinder, and a pair of horizontal sealing rolls that seal the cylindrical laminated film at regular intervals across the entire width while filling it with the packaged items, forming horizontal seals.

JP 2005-96849 A

The laminated packaging film used in such vertical filling and packaging machines usually comprises a base layer and a sealant layer, and is folded in two at the center in the width direction so that the sealant layers face each other. The laminated packaging film folded in two is sandwiched between a pair of vertical sealing rolls and a pair of horizontal sealing rolls, and is heated and pressurized to fusion-bond (heat seal) the facing sealant layers together, forming vertical and horizontal seals, and a packaging bag is formed in a continuous manner.

When a vertical filling and packaging machine is operated at high speed, a pair of vertical sealing rolls and a pair of horizontal sealing rolls must apply an extremely high temperature from the outermost layer side (base layer side) to melt and fuse the sealant layers that are located in the innermost layers and face each other. However, doing so can cause thermal damage to the packaging laminate film, and there is a risk of wrinkles and bubbles forming in the sealed area, resulting in a decrease in quality.

Conventionally, therefore, the filling speed is reduced and the heating time is extended to allow for a wider range of heat sealing temperatures, but this method reduces the productivity of packaging bags and leaves room for improvement.

The objective of this invention is to solve the problems associated with the conventional technology, and to provide a laminated film for packaging that enables high-speed operation of the filling and packaging machine and improves the productivity of packaging bags.

The laminated packaging film of the present invention is a laminated packaging film used in a filling and packaging machine equipped with a heat sealing means, and comprises at least a base layer and a sealant layer, the sealant layer having a structure of at least two layers, the outermost sealant layer of the sealant layers not containing an inorganic filler, and one or more sealant layers other than the outermost sealant layer containing an inorganic filler having a particle size of 1 to 20 μm in an amount of 16% by weight to 40% by weight of the entire sealant layer.

In the packaging laminate film of the present invention , it is a more preferred solution that the inorganic filler is at least one compound selected from calcium carbonate, silica, talc, zeolite, titanium oxide, alumina, zinc oxide, magnesium oxide, boron nitride and aluminum nitride.

In the packaging laminate film according to the present invention, the sealant layer has at least a two-layer structure, and at least one of the sealant layers other than the outermost sealant layer contains an inorganic filler with high thermal conductivity or thermal diffusivity, so that heat from the heat sealing means (such as a heat seal roll) can be efficiently transferred to the sealant layer. This makes it possible to expand the temperature range when heat sealing the packaging laminate film with the heat sealing means, and also enables high-speed operation, improving productivity.

1 is a cross-sectional view showing one embodiment of a packaging laminate film according to the present invention. FIG. 1 is a diagram showing a vertical filling and packaging machine as an example of a filling and packaging machine. FIG. 2 is a cross-sectional view of a packaging laminate film used in the examples. FIG. 2 is a graph showing the relationship between heat sealing temperature and heat sealing strength in the examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
Fig. 1 is a cross-sectional view showing one embodiment of the packaging laminate film according to the present invention, Fig. 2 is a diagram showing a vertical filling and packaging machine as an example of the filling and packaging machine.

In FIG. 1, reference numeral 1 denotes a packaging laminate film, reference numeral 2 denotes a base layer, reference numeral 3 denotes an intermediate layer, and reference numeral 4 denotes a sealant layer. The sealant layer 4 has a two-layer structure consisting of a first sealant layer 4a located on the intermediate layer 3 side and a second sealant layer 4b located on the outermost layer. In this embodiment, the intermediate layer 3 is provided between the base layer 2 and the sealant layer 4, but the intermediate layer 3 is not essential and may be laminated as appropriate.

The packaging laminate film 1 can be formed by sequentially laminating the first sealant layer 4a and the second sealant layer 4b to the required thickness using a tandem extrusion laminator on the substrate layer 2 or on a laminate film consisting of the substrate layer 2 and the intermediate layer 3, or by co-extrusion laminating the resins that make up each layer. Alternatively, the first sealant layer 4a and the second sealant layer 4b may be formed in advance by a cast molding method, an inflation molding method, or the like, and then laminated on the substrate layer 2 or on a laminate film consisting of the substrate layer 2 and the intermediate layer 3 by a dry lamination method, an extrusion lamination method, or the like.

Incidentally, the packaging laminate film 1 is used in a filling packaging machine having a heat sealing means, and can be suitably used in, for example, the vertical filling packaging machine shown in Fig. 2. The filling packaging machine may be a vertical pillow filling packaging machine, a horizontal pillow filling packaging machine, a multi-row filling packaging machine, or the like.
In this vertical filling and packaging machine, a long length of packaging laminate film 1 is continuously unwound from an original roll 11 and, while running in the longitudinal direction, is folded back in the width direction at a film folding back section 12 so that the sealant layers 4 face each other, and the overlapping side edges are continuously heat-sealed in the longitudinal direction by a pair of vertical sealing rolls of a vertical sealing means 13 to create a vertical seal section 14. The thus-formed cylindrical packaging laminate film 1 is continuously filled with packaged items M from a filling nozzle of a supply section 15, and a horizontal seal section 17 is formed across the entire width of the cylindrical packaging laminate film 1 while squeezing out the packaged items M with a pair of horizontal sealing rolls of a horizontal sealing means 16. The horizontal seal section 17 is then cooled by a pair of horizontal sealing rolls of a cooling section 18 to fix the bond, thereby producing a large number of packaging bags P and automatically filling each packaging bag P with the packaged items M.

Each layer constituting the packaging laminate film 1 will now be described.
The base layer 2 is not particularly limited, but may be composed of, for example, a polyester film such as a polyethylene terephthalate film (PET) or polyethylene naphthalate, a polyolefin film such as a biaxially oriented polyethylene film or a biaxially oriented polypropylene film, a biaxially oriented nylon film, a polyvinyl alcohol film, an ethylene-vinyl alcohol copolymer film, paper, etc. The base layer 2 may be vapor-deposited or coated with an oxide, nitride, or chloride of silicon, aluminum, titanium, etc. The thickness of the base layer 2 is appropriately selected depending on the application, etc., but is preferably in the range of 9 to 80 μm in order to increase the strength, stiffness, barrier properties against gases, etc., and pinhole resistance of the packaging laminate film 1.

The intermediate layer 3 is not particularly limited, but may be made of the same film material as the base layer 2. The intermediate layer 3 is provided to impart gas barrier properties, pinhole resistance, stiffness, light-shielding properties, etc. to the packaging laminate film 1, and may be selected appropriately according to the required properties, and multiple layers may be provided. For example, when aluminum foil is formed as the intermediate layer 3, it is possible to impart gas barrier properties and light-shielding properties to the packaging laminate film 1.

In FIG. 1, the sealant layer 4 is shown to have a two-layer structure of a first sealant layer 4a and a second sealant layer 4b, but the number of layers is not particularly limited and the sealant layer 4 is composed of at least two layers. The first sealant layer 4a located on the intermediate layer 3 side serves to bond the second sealant layer 4b and the intermediate layer 3 well, and the second sealant layer 4b serves to fuse and bond the layers by heating and pressurizing using a heat sealing means (e.g., vertical sealing means 13 and horizontal sealing means 16 in FIG. 2) to form a heat-sealed portion (e.g., vertical sealing portion 14 and horizontal sealing portion 17 in FIG. 2).

The sealant layer 4 is made of, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polypropylene-ethylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ionomer resin, etc., and low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene are preferably used, particularly when the packaged product is filled and packaged by a submerged sealing method (a method in which the packaged product is squeezed out by a horizontal sealing means while the squeezed-out position is heat-sealed to form a horizontal seal portion) as in the vertical filling and packaging machine of Figure 2.

The first sealant layer 4a is mainly composed of, for example, low-density polyethylene and contains inorganic filler 5. The inorganic filler 5 is made of a material with excellent thermal conductivity or thermal diffusivity, and may be, for example, calcium carbonate, silica, zeolite, titanium oxide, alumina, zinc oxide, magnesium oxide, boron nitride, alumina nitride, etc., which may be used alone or in combination of two or more types. In particular, when the packaged item is food or drink, it is preferable to select the inorganic filler 5 taking into consideration laws and regulations such as the Food Sanitation Act. There are no particular limitations on the size of the inorganic filler 5, but inorganic fillers of about 1 μm to 20 μm are preferable because they are easy to control and disperse as a powder and have a stable surface.

By incorporating inorganic filler 5 into the first sealant layer 4a, the thermal conductivity or thermal diffusivity of the first sealant layer 4a is improved, and heat from the heat sealing means (e.g., vertical sealing means 13 and horizontal sealing means 16 in FIG. 2) can be efficiently supplied to the second sealant layer 4b. This broadens the lower limit of the sealable temperature range in the filling and packaging machine, making it possible to form a seal section (e.g., vertical sealing section 14 and horizontal sealing section 17 in FIG. 2) with sufficient seal strength even at a low heat sealing temperature. Moreover, heat from the heat sealing means can be supplied to the second sealant layer 4b in a short time, enabling high-speed filling and improving productivity.

Furthermore, by using a natural material such as calcium carbonate for the inorganic filler 5, the amount of plastic resin in the packaging laminate film 1 can be reduced, which is expected to have an environmental effect.

When the sealant layer 4 is made up of three or more layers, the inorganic filler 5 may be added to any layer of the sealant layer 4 other than the outermost sealant layer, or may be added to multiple layers, and the same effect can be expected in either case.

The content of the inorganic filler 5 is in the range of 16 to 40% by weight in the entire sealant layer 4. If the content is less than 16 % by weight, the inorganic filler 5 does not improve the thermal conductivity or thermal diffusivity of the sealant layer 4, and the temperature at which the seal can be made by the heat sealing means cannot be lowered. On the other hand, if the content exceeds 40% by weight, the amount of resin in the sealant layer 4 decreases, resulting in problems such as a decrease in the seal strength.

Example 1
Packaging bags were produced using the packaging laminate films of Comparative Example, Reference Examples 1-2, and Examples 3-6 shown in Table 1 with a vertical fill-seal machine (DANGAN (registered trademark) G2 standard machine, manufactured by Taisei Lamic Co., Ltd.) shown in Fig. 2. The packaging laminate films of Reference Examples 1-2 and Examples 3-6 have a sealant layer 4 with a three-layer structure (first sealant layer 4a, second sealant layer 4b, and third sealant layer 4c) as shown in Fig. 3. 5-50% by weight of a master batch ( _CaCO3 ) with a calcium carbonate concentration of 80% by weight was added to the second sealant layer 4b as the inorganic filler 5 so that calcium carbonate ( _CaCO3 ) was 4-40% by weight.

The vertical seal temperature (vertical seal means 13 in FIG. 2) of the vertical fill-seal machine was set to 195°C, and the horizontal seal temperature (horizontal seal means 16 in FIG. 2) was varied in the range of 115-195°C, and a pressure resistance test was conducted on each of the produced packaging bags (a pressure force was applied from above while the packaging bag was laid horizontally, and the pressure until the bag broke was measured). The results are shown in Table 2. The bag production conditions were as follows. The first sealant layer 4a, the second sealant layer 4b, and the third sealant layer 4c were laminated by extrusion lamination.
Bag dimensions: length 48mm x width 63mm
Filling speed: 15m/min
Vertical seal temperature: 195°C
Vertical seal pressure (MPa): 110/70
Horizontal seal pressure (MPa): 300/250
Contents: 15g water
Liquid temperature: 30℃

From the results in Table 2, it was confirmed that in all of Examples 3 to 6, the addition of inorganic filler 5 to the second sealant layer 4b improved the thermal conductivity or thermal diffusivity of the second sealant layer 4b, and compared to the comparative example in which inorganic filler 5 was not added, the lower limit of the transverse sealable temperature range was expanded, and filling and packaging at a higher speed than before became possible. In addition, in Example 6 (CaCO ₃ : 40% by weight), even when the transverse sealing temperature was lowered to 120°C, no unfused areas or conduction occurred in the heat-sealed part, and a packaging bag having a pressure resistance of about 120 kgf was produced. In addition, in Examples 3 to 5 (CaCO ₃ : 16 to 32% by weight), even when the transverse sealing temperature was lowered to 140°C, a high pressure resistance of 540 kgf or more was shown, and it was confirmed that it can be suitably used even when filling and packaging a packaged item that requires a high pressure resistance, such as a liquid.

Example 2
For the packaging laminate films of Comparative Examples, Reference Examples 1 and 2, and Examples 3 to 6 shown in Table 1, heat-sealed portions were formed using a pair of heat seal bars under conditions of temperature: 65 to 140°C and pressure: 0.2 MPa x 1 second, and the seal strength of each heat-sealed portion was measured.
The seal strength was measured by opening the test piece 180° with the heat-sealed part in the center, attaching both ends of the test piece to the grips of a tensile tester (grip interval 50 mm), applying a tensile load until the heat-sealed part broke, and determining the maximum load (N/15 mm) during that time. The results are shown in Figure 4. The number of measurements was 5 for each test piece, and the average value was used.

From the results in FIG. 4, Example 3 (CaCO ₃ : 16 wt %) exhibited heat seal strength equivalent to that of the Comparative Example at all heat seal temperatures, and no effect of the addition of the inorganic filler was confirmed.
When the heat sealing temperature exceeded 100°C, the seal strength tended to decrease as the amount of inorganic filler added increased. However, when the heat sealing temperature was 95°C or higher, all of the packaging laminate films of Examples 3 to 6 exhibited a high heat seal strength of 40 N/15 mm or more, and it was confirmed that they can be suitably used as packaging bags.

The laminated packaging film of this invention can be used in vertical fill packaging machines, vertical pillow fill packaging machines, horizontal pillow fill packaging machines, multi-row fill packaging machines, etc.

Reference Signs List 1 Laminated film for packaging 2 Base layer 3 Intermediate layer 4 Sealant layer 4a First sealant layer 4b Second sealant layer 4c Third sealant layer 5 Inorganic filler 11 Raw roll 12 Film folding section 13 Vertical sealing means 14 Vertical sealing section 15 Supply section 16 Horizontal sealing means 17 Horizontal sealing section 18 Cooling section M Packaged item P Packaging bag

Claims (2)

A packaging laminate film for use in a filling and packaging machine equipped with a heat sealing means,
The adhesive sheet includes at least a base layer and a sealant layer.
The sealant layer has at least a two-layer structure,
The laminated film for packaging is characterized in that, among the sealant layers , the outermost sealant layer does not contain an inorganic filler, and at least one of the sealant layers other than the outermost sealant layer contains an inorganic filler having a particle size of 1 to 20 μm in an amount of 16% by weight to 40% by weight of the entire sealant layer. The packaging laminate film according to claim 1, characterized in that the inorganic filler is at least one compound selected from calcium carbonate, silica, talc, zeolite, titanium oxide, alumina, zinc oxide, magnesium oxide, boron nitride and aluminum nitride.

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