JPH0449035A - Heat-shrinkable film for packaging dry cell - Google Patents

Abstract

PURPOSE:To make heat shrinkage operation for packaging a dry cell easy and to improve strength of a sealed part by constituting the title film of a multi-layered film having at least three layers prepd. by laminating a polyamide resin layer, an adhesive resin layer and a polyethylene resin layer in this order and specifying the total thickness of the multi-layered film. CONSTITUTION:The title film is constituted of a multi-layered film having at least three layers preped. by laminating a polyamide resin layer, an adhesive resin layer and a polyethylene resin layer in this order and the total thickness of 10-40 mum. As the polyamide resin, not only nylon 6, nylon 66, nylon 610 and nylon 12 but also copolyamides such as nylon6-66 copolymer and nylon 6-610 copolymer can be cited. As the adhesive resin, as far as the resin has adhesive properties with both the polyamide resin layer and the polyethylene resin layer such as modified polyolefin resins and ionomer resins, there exists no specified limitation. In addition, as the polyethylene resin, if it is a copolymer with at least ethylene part such as a copolymer of ethylene with another olefin or a non-olefinic monomer, there exists no specified limitation.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a heat-shrinkable film for packaging dry batteries with excellent strength.

BACKGROUND ART Various types of heat-shrinkable films for packaging dry cell batteries have been seen here and there, with those made of polyvinyl chloride and polyethylene being the most widely used. However, those made of polyvinyl chloride tend to lack the impact weight resistance of the sealed portion and the strength against drop impact, and the packaged products must be handled with care. On the other hand, those made of polyethylene have satisfactory sill strength, but because of their low melting point, they tend to melt during the heat shrinking process and cause holes, and in this respect they cannot be said to be undesirable.

<Problems to be solved by the invention> In view of the current situation, we have searched for a material that has excellent strength for the sealing part and is easy to perform the heat shrinking process, and as a result, we have found that it is difficult to obtain a material that satisfies all of these requirements with a single material. Ta. Therefore, the present inventors conducted further studies in order to solve the conventional problems by studying laminated heat-shrinkable films, and as a result, they finally arrived at the present invention.

Means for Solving the Problems> The present invention provides a heat-shrinkable film for packaging dry batteries, which has at least three layers including a polyamide resin layer, an adhesive resin layer, and a polyethylene resin layer laminated in this order. The total thickness is 10.
It is characterized by having a thickness of ~40 μm.

Next, I will discuss in detail the means to solve the problem.

The polyamide resin (A) according to the present invention is nylon 6,
In addition to nylon 66, nylon 610, nylon 12, etc., copolyamides such as nylon 6-66 copolymer and nylon 6-610 copolymer can be exemplified, and furthermore, structures having an aromatic ring in the main chain or 9111m Examples include so-called aromatic polyamide resins. Furthermore, mixtures of the resins exemplified above can also be used, and the polyamide resin is not particularly limited.

The adhesive resin (B) is not particularly limited as long as it has adhesive properties with both the polyamide resin layer and the polyethylene resin layer, such as modified polyolefin resin, ionomer resin, etc., and is preferably one that can be coextruded with both of the above. Adhesive resins are more preferred.

The modified polyolefin resins mentioned above include olefins alone or copolymers, such as maleic acid,
Copolymerization of unsaturated carboxylic acids such as fumaric acid and acrylic acid, or derivatives such as their acid anhydrides, esters, and metal salts,
For example, a graft copolymerized modified polymer can be exemplified as a representative example, and the modified polyolefin resins include the modified polyolefin resins alone or in mixtures with other components, such as other polyolefin resins. In this case, the above-mentioned olefins include high, medium, and low density polyethylene, linear low density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-dithyl acrylate copolymer, and ethylene-vinyl acetate copolymer. Examples include merging.

Examples of the polyethylene resin () include the same as the polyolefins mentioned above, and in short, there is no particular restriction as long as it is a copolymer containing at least an ethylene portion, such as a copolymer of ethylene and another olefin or non-olefin monomer. It is also possible to use a modified ethylene resin, an ionomer resin (the same resin as the adhesive resin layer is not used), etc. used for the adhesive resin layer.

If necessary, other appropriate third materials may be added to the layer made of each of the resins (A), CB, and (C) at any time.

Any such multilayer film can be used as long as it has the above-mentioned fA), (B), and (C) layers as its basic structure and has a total thickness of 10 to 40 μm, and the preferred multilayer film structure is A/B/C, C. /B/A/B/C1 B, /B, /A/B/C.

B, /B/A/B/C, B/A/B/C (here B, B
, indicates a different type of adhesive resin from B). Of course, it is also possible to apply a resin layer made of another third component, but the total thickness must be in the range of 10 to 40 μm.

If the total thickness is less than 10μ, the strength may be insufficient or the strength of the seal portion may be insufficient; if it exceeds 40μ, it is too thick and has a poor texture, making it impossible to provide a preferable package.

The preferred thicknesses of the individual layers constituting the multilayer film will now be stated. For example, the polyamide layer may have a thickness of 5 to 15μ, the adhesive resin layer may have a thickness of 1 to 10μ, and the ethylene polymer layer may have a thickness of approximately 1 to 15μ. It may be a range.

To package dry batteries, a plurality of dry batteries may be packaged together or one by one, but generally two or four batteries are packaged together.

The packaging may be of any type, such as overlap packaging or sleeve packaging, but generally multiple dry batteries are overlapped so that the axial direction of the batteries is perpendicular to the axial direction of the packaging, and predetermined portions are fused and sealed or pasted on the back. Sleeve-shaped packaging is often used, in which the batteries are crimped and sealed, the inner corners are cut, and the batteries are heat-shrinked. Of course, it is not necessary to wrap the entire dry battery.

In the present invention, the film may be formed as a tube-shaped film by the inflation method using an appropriate device such as co-extrusion, or a flat-shaped film by the co-extrusion T-die method, but there is no particular restriction, however, it is necessary to have heat shrinkability. There is,
There are no particular restrictions on heat shrinkage, but for example, 100°C
When immersed in hot water for 30 seconds at
Examples of preferable examples include those having a heat shrinkage rate of 0%, and the latter having a heat shrinkage rate of about 30 to 60%.

In order to impart heat shrinkability, it is necessary to perform stretching, and an example of stretching is a method in which film formation is performed by cooling and then reheating. Furthermore, heat shrinkability may be imparted by a melt-stretching method, that is, a method in which extrusion film formation and stretching are performed simultaneously.
The stretching ratio is also not particularly limited, but can be, for example, 1.0 to 4 times in the vertical direction and 2 to 5 times in the horizontal direction, and the stretching temperature is also not particularly limited, but is usually 60 to 150°C, preferably 70 to 70°C. 12
An example is about 0°C.

The preferred configurations of the present invention have been described above by way of example, and the present invention is not limited to such descriptions and can take on any embodiments within the scope of the claims.

Example l Nylon 6-66 copolymer (A),! Adhesive resin containing modified linear low-density polyethylene (B), linear low-density polyethylene (C) containing water-maleic acid kraft copolymerized
C, /B/A/B/C (7) were co-extruded into a 5-layer structure in a flat shape, then longitudinally stretched 3 times at a temperature of 80°C, and then stretched 4 times by a tenter at a temperature of 100°C. A heat-shrinkable film was obtained by stretching in the transverse direction and having a heat shrinkage rate of 20% in the longitudinal direction and 40% in the transverse direction in hot water at 100° C. for 30 seconds. The total thickness of such a film is 18 μm, and the A layer is 10 μm.
Both the m and B layers were 2 μm in thickness, and the C layers were both 2 μm in thickness. The C layer acted as a heat seal layer.

The film thus obtained was cut into a predetermined size and made into a sleeve by fusing and sealing. When four D batteries were inserted into the sleeve so that their axial direction was perpendicular to the axial direction of the sleeve and heat-shrinked, the four batteries were firmly engaged and a beautiful-looking package was completed. .

Comparative Example Polyvinyl chloride was stretched by a conventional method to a thickness of 25 μm.
, the heat shrinkage rate is 20% in the longitudinal direction and 4 in the transverse direction in hot water for 30 seconds.
A 0% heat shrinkable film was created.

Table 1 shows a comparison of the impact strength and drop impact strength of the film thus obtained and the film obtained in the above examples.

Table 1 <Effects of the Invention> The present invention provides a heat-shrinkable film suitable for packaging dry batteries, and when such a film is used to package dry batteries, the heat-shrinking work is easy and the strength of the sealed portion is excellent. , during transportation,
There are very few accidents where the packaging breaks during handling, etc.
This has special effects such as ensuring beautiful packaging.

Claims (1)

[Claims] It is composed of a multilayer film having at least three layers in which a polyamide resin layer, an adhesive resin layer, and a polyethylene resin layer are laminated in this order, and the total thickness of the multilayer film is 10 to 40 μm. A heat-shrinkable film for packaging dry batteries, which is characterized by: