JPH0920364A - Laminated film for packaging bag for fluid in liquid state - Google Patents

Abstract

PURPOSE: To provide a laminated film for packaging bags for a fluid product in a liquid state, which has an excellent pressure-proof strength. CONSTITUTION: A base film forming the outermost layer is laminated on the inner surface with a resin film forming an intermediate layer by use of an anchor coat or a layer of an adhesive therebetween and furthermore laminated on the inner surface with a resin film forming the innermost layer. The resin forming the intermediate layer consists of straight-chain low-density polyethylene (a) or a resin based thereon and prepared by incorporating therewith high- pressure low-density polyethylene (b) with (a):(b) in a ratio by weight of 100-20:0-80 as occasion demands. The resin film forming the innermost layer is a film of low density polyethylene obtained by using a metallocene catalyst or a multilayer film including one or more layers of the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film for packaging bags of liquid fluid products, and more particularly to a laminated film for packaging bags which is excellent in pressure resistance when the liquid fluid products are filled and packaged. is there.

[0002]

2. Description of the Related Art As is well known, various liquid fluid products such as soup, sauce, miso and wasabi are usually packed in vertical pillows. The outline of filling packaging in vertical pillow packaging is as follows. That is, in the filling and packaging machine, the film for a packaging bag supplied downward from above is formed into a cylindrical shape and center-sealed, and the lower side of the obtained cylindrical body is sealed to form a cylindrical container. The filling nozzle is inserted from the upper side to fill a certain amount of the liquid fluid product, and then the upper side of the cylindrical container is sealed to complete the packaging. Then, such a packaging operation is continuously performed to obtain a packaged product of a plurality of continuous packages, and then each packaged product is separated.

[0003]

By the way, various characteristics are required for a film for a packaging bag for liquid fluid products, and pressure resistance is one of the important characteristics. Here, the compressive strength means the load when a liquid flow product is filled and packaged in a packaging bag and a certain load is applied from above to break the bag. Therefore, if the pressure resistance is insufficient,
Not only is it difficult to increase the filling speed in vertical pillow packaging, but it also causes bag breakage during inventory and transportation, and contaminates unbroken packaged products with liquid fluid products that flow out due to bag breakage. Cause problems.

Recently, a low-density polyethylene resin obtained by using a metallocene catalyst has attracted attention, and in order to utilize its excellent characteristics, the resin film or a multilayer containing more than one of the film by an inflation method or a T-die method. Attempts have been made to use the film in a vertical pillow packaging film. That is, the extrusion lamination method is adopted, and the base film forming the outermost layer and the above-mentioned film are laminated with a molten resin to obtain a laminated film, which is used for a packaging bag. And, as the molten resin for bonding, high-pressure low density polyethylene or polypropylene is usually used.

However, the laminated film having the layer structure obtained as described above has a drawback that the pressure resistance is not sufficient. The present invention has been made in view of such circumstances, and an object thereof is a low-density polyethylene resin film obtained by using a metallocene catalyst or a laminated film containing a multilayer film containing one or more of the film in a layer structure. Therefore, it is an object of the present invention to provide a laminated film for packaging bags of liquid fluid products, which has excellent pressure resistance.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a low-density polyethylene resin film obtained by using a metallocene catalyst or one or more of the film is contained. It was surprisingly found that if a linear low-density polyethylene resin film is laminated and used on a multi-layer film, the pressure resistance is improved.

The present invention has been completed based on the above findings, and the gist thereof is to form an intermediate layer on the inner surface of a base film forming an outermost layer via an anchor coat agent layer or an adhesive layer. Resin film forming the innermost layer is further laminated on the inner surface of the resin film, and the resin forming the intermediate layer is a linear low density polyethylene (a).
And a high-pressure low-density polyethylene (b) blended as necessary, and the weight ratio of (a) :( b) is 100 to
20: 0 to 80, wherein the resin film forming the innermost layer is a low-density polyethylene resin film obtained by using a metallocene catalyst or a multi-layer film containing one or more of the film, which is a liquid fluid product. It exists in the laminated film for packaging bags.

The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing an example of the layer structure of the laminated film of the present invention. In the following description, the linear low-density polyethylene resin is abbreviated as “LLDPE”,
The low density polyethylene resin obtained by using the metallocene catalyst is abbreviated as "M-LDPE".

As shown in FIG. 1, the laminated film of the present invention comprises an outermost layer (1), an anchor coating layer (or an adhesive layer) (2), an intermediate layer (3) and an innermost layer (4). To be done.

As the constituent resin of the base film forming the outermost layer (1), various resins which have been conventionally used for laminated films for packaging bags of liquid fluid products are used, and specific examples thereof include polypropylene film. (PP), nylon (NY), polyethylene terephthalate film (P
ET), ethylene-vinyl alcohol copolymer (EV
OH), polyvinyl alcohol (PVA) and the like. These resins are usually uniaxially or biaxially stretched to form a film. And, biaxially stretched NY, P
ET or EVOH film, especially biaxially stretched NY
A film is preferably used.

As the base material film, in addition to the above-mentioned resin film, vinylidene chloride coated film, vapor deposition film of aluminum or silicon oxide can be used, and further, aluminum foil or a laminated film of the same film can be used. You can The thickness of the base film is usually 8 to
It is 70 μm, preferably 12 to 42 μm. Printing may be performed on the front surface or the back surface of the base film (the laminated surface in the case of a laminated film).

As the anchor coating agent layer (2), an anchor coating agent or an adhesive agent such as isocyanate type, polyester / isocyanate type, polyether / isocyanate type, polyethyleneimine type, organic titanate type, polybutadiene type is usually used. It They are,
The dry coating amount is usually 0.01 to 1.0 g / m.
² , preferably in the range of 0.05 to 0.58 g / m ² .

The resin forming the intermediate layer (3) is LLDP.
It is composed of E (a) and a high-pressure low-density polyethylene (b) optionally blended. LLDPE (a) is a copolymer of ethylene and α-olefin having 4 to 12 carbon atoms, and its density is usually 0.88 to 0.94 g / c.
m ³ , preferably 0.905 to 0.925 g / cm ³ . The above copolymer is obtained by copolymerizing ethylene and the above α-olefin by a gas phase method, a liquid phase method, or a solution method using a chromium-based catalyst or a Ziegler-based catalyst, and a melt index thereof. (MFR) is usually 0.
It is 1 to 50, preferably 4 to 20 (g / 10 min.).

And, as the above-mentioned α-olefin,
Specifically, butene-1, pentene-1, hexene-
1, Heptene-1, Octene-1, 4-methylpentene-1 and the like are used. High pressure low density polyethylene (b)
Is blended as necessary to improve the processability of LLDPE (a), but the weight ratio of (a) :( b) is usually 100 to 20: 0 to 80, preferably 80:50 to. Two
It is set to 0:50. The thickness of the resin film forming the intermediate layer (3) is usually 8 to 40 μm, preferably 10 to 30.
μm.

The resin film forming the innermost layer (4) is
It is an M-LDPE film or a multi-layer film containing one or more such films. M-LDPE is obtained by copolymerizing ethylene and α-olefin as described above by a gas phase method, a liquid phase method or a solution method using a metallocene catalyst (single site catalyst). As is well known, such a copolymer has a very sharp molecular weight distribution (for example, Mw / Mn).
= 2 to 3.5), and is a very homogeneous polymer having a very sharp composition distribution. The density of M-LDPE is usually 0.87 to 0.95 g / cm ³ , preferably 0.89.
Is about 0.93 g / cm ³ .

A multi-layer film containing more than one M-LDPE film is a M-LDPE film and a conventional LLDPE film.
A two-layer film with a film is preferably used. Such a two-layer film is obtained by the inflation method or the T-die method. In the above two-layer film, M-L
The DPE film side forms the innermost layer. The thickness of the resin film forming the innermost layer (4) is usually 8 to 100 μm,
It is preferably 25 to 70 μm.

In the laminated film of the present invention, for example, the anchor coating agent is applied to the surface of the base film forming the outermost layer (1) and dried to form the anchor coating agent layer (2) on the inner surface of the base film. As a resin film for forming and forming an intermediate layer (3), molten LLDPE extruded from a die is used as a laminating resin, and the innermost layer is formed on the anchor coat agent layer (2) side of the outermost layer (1). It can be manufactured by laminating the resin film (M-LDPE film) constituting (4).

The laminated film of the present invention is used as a packaging bag for liquid fluid products.
In addition to the liquid and viscous products described above, various gel-state products can be mentioned. The vertical pillow packaging of these liquid fluid products is carried out by a filling and packaging machine using the laminated film of the present invention, and the form of the packaging bag may be a three-sided bag, a twin pack, a bottle type bag or the like. Further, according to the laminated film of the present invention, it is possible to obtain a packaged product which utilizes the excellent heat-sealing property of the M-LDPE film and has excellent pressure resistance.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 As a base film, a printed film having a thickness of 15 μm was used.
m biaxially stretched nylon film (ONY) (manufactured by Toyobo Co., Ltd.), as an anchor coating agent, an isocyanate-based anchor coating agent, and as LLDPE, ethylene.
Hexene-1 copolymer and low density polyethylene (content 2
5% by weight) blended product (trade name “DL” manufactured by Tosoh Corporation)
Y03 "), as the M-LDPE film, a product name" WMX-120 "manufactured by Wada Chemical Industry Co., Ltd. (a single-layer film made of a low-density polyethylene resin obtained by using a metallocene catalyst and having a thickness of 35 µm) is used. did.

An anchor coating agent was applied to the surface of the base film and dried to form an anchor coating layer on the inner surface of the base film. The coating amount of the anchor coating agent after drying was 0.3 g / m ² . And melt LLD from die
PE is extruded to a thickness of 15 μm, the LLDPE film is used as a laminating resin, and the M-LDPE film is laminated on the anchor coat agent layer side of the base film to obtain a laminated film having a total thickness of 65.3 μm. It was

Next, using a vertical pillow liquid filling and packaging machine (SKL-1000 manufactured by Komatsu Seisakusho Co., Ltd.), under the conditions of a vertical roll temperature of 210 ° C. and a horizontal roll temperature of 175 ° C., a three-sided package composed of the above-mentioned laminated film Bag (65 mm x 8
0 mm) was filled with 15 ml of water. The filling speed was variously changed, and the pressure resistance of each of the obtained packages was measured. The results are shown in Table 1. In addition, the compressive strength was measured for each of the four packaged products obtained by separating the four packaged products.

Comparative Example 1 In Example 1, LLDPE (trade name "DLY0
3 ") was replaced with high-pressure low-density polyethylene having a density of 0.92 g / cm ³ , and a laminated film having an overall thickness of 65.3 μm was obtained in the same manner as in Example 1. Then, in the same manner as in Example 1, water was filled as a three-sided packaging bag and the pressure resistance was measured. The results are shown in Table 1.

Example 2 As a base film, a biaxially stretched nylon film (ONY) (manufactured by Toyobo Co., Ltd.) having a thickness of 15 μm and not printed on the surface, and an isocyanate-based anchor coat as an anchor coating agent As an agent, LLDPE, a blended product of ethylene-hexene-1 copolymer and high-pressure low-density polyethylene (content: 25% by weight) (trade name "4P20A" manufactured by Tosoh Corp.), M-LDPE film,
Kojin Co., Ltd. product name "Kojin Metalloace" (composed of a low-density polyethylene resin film obtained by using a metallocene catalyst and a normal linear low-density polyethylene resin film, the former: the latter having a thickness ratio of 1 : 4, a multilayer film having a total thickness of 30 μm) was used.

An anchor coating agent was applied to the surface of the base film and dried to form an anchor coating layer on the inner surface of the base film. The coating amount of the anchor coating agent after drying was 0.3 g / m ² . And melt LLD from die
PE is extruded at a thickness of 20 μm, the LLDPE film is used as a laminating resin, and the M-LDPE film is laminated on the anchor coat agent layer side of the base film to obtain a laminated film having a total thickness of 65.3 μm. It was Then, in the same manner as in Example 1, water was filled as a three-sided packaging bag and the pressure resistance was measured. Table 2 shows the results.

Comparative Example 2 In Example 2, LLDPE (trade name “4P20
A laminated film having an overall thickness of 65.3 μm was obtained in the same manner as in Example 2 except that high-pressure low-density polyethylene having a density of 0.92 g / cm ³ was used instead of A ”). Then, in the same manner as in Example 1, water was filled as a three-sided packaging bag and the pressure resistance was measured. Table 2 shows the results.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

The laminated film for a packaging bag according to the present invention described above has excellent pressure resistance when used as a packaged product. Therefore, in the packaged product of a liquid fluid product using the laminated film of the present invention, bag breakage during inventory or transportation is prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a layer structure of a laminated film of the present invention.

[Explanation of symbols]

 1: Outermost layer 2: Anchor coat agent layer 3: Intermediate layer 4: Innermost layer

Claims (1)

[Claims] 1. A resin film constituting an intermediate layer is laminated on an inner surface of a base film forming an outermost layer via an anchor coating agent layer or an adhesive layer, and further, a resin film constituting an innermost layer on the inner surface thereof. And a resin constituting the intermediate layer is composed of a linear low-density polyethylene (a) and a high-pressure low-density polyethylene (b) optionally blended, (a): (b) The weight ratio of 100 to 20: 0
80, and the resin film forming the innermost layer is a low-density polyethylene resin film obtained by using a metallocene catalyst, or a multilayer film containing one or more of the film, for a liquid fluid product packaging bag. Laminated film.