JPH04307224A - Jacket film for dry cell - Google Patents

Abstract

PURPOSE:To package a dry cell in the same manner as the jacket of a metal by using a jacket film for the dry cell in this invention as the jacket of the dry cell, and to increase the internal capacity of the dry cell having the same shape by reducing the thickness of a jacket material to approximately the quarter of the metal. CONSTITUTION:Silicon oxide and magnesium stearate are mixed with a PET resin having a specific IV value, and extruded from an extruder in a filmy shape and quenched, thus obtaining a non-oriented film. The non-oriented film obtained is uniaxial-oriented under specific conditions, and thermally fixed, thus acquiring a uniaxial oriented film having a specific shrinkage factor. The uniaxial oriented film acquired is fabricated, thus manufacturing a jacket film for a dry cell.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry cell jacket film used for the outer packaging portion of a dry cell jacket.

0002

[Prior Art] Dry batteries are determined to have a fixed length, outer diameter, etc. due to usage issues, and metal is used as the material for the jacket in consideration of durability, workability, etc. Ta.

However, recently, there has been a desire for dry batteries to have increased battery capacity and reduced weight while maintaining the same size. For this reason, attempts have been made to make the metal of the outer package of the battery jacket thinner or to use a plastic film to meet the above requirements. Due to problems with fastening, durability, etc., shrink packaging using plastic films that do not require crimping has been considered. P
(ET) type films have been put into practical use.

0004

[Problems to be Solved by the Invention] However, the above-mentioned PVC film has problems in heat resistance and softens during use in OA equipment and the like.

In addition, biaxially stretched PET film has good shrinkability in the shrink tunnel in the shrinking process after labeling the dry cell in the direction of the body wrapping of the dry cell; However, it also contracted significantly, which caused problems as an outer packaging.

The object of the present invention is to provide a dry battery that can increase the capacity of the battery, is lightweight, has good heat resistance, and has a large shrinkage in one direction and a moderate shrinkage in the right angle direction. An object of the present invention is to provide a jacket film for a dry battery having shrinkage properties suitable for an outer package.

[0007]

[Means for Solving the Problems] As a result of intensive studies, the present inventors have found that among polyethylene terephthalate resin films, a film having a specific shrinkage rate is suitable for the outer packaging of a dry battery jacket, and has completed the present invention. reached.

That is, the present invention has an intrinsic viscosity of 0.6 to 0.8.
A film made of polyethylene terephthalate resin, characterized in that the heat shrinkage rate after being left in an oven at 100°C for 15 minutes is 30% or more in the stretching direction and 10% or less in the direction perpendicular to the stretching direction. This is a jacket film for dry batteries.

[0009] The PET resin used in the present invention is
It is a resin with high heat resistance among general-purpose resins, and is easy to perform primary processing and secondary processing.

[0010] The PET resin used in the present invention is a PET resin with an intrinsic viscosity (hereinafter referred to as IV) of 0.6 to 0.8, preferably a PET resin with an IV of 0.62 to 0.74.
It is a type resin. When IV is less than 0.6, stretching unevenness tends to occur when the stretching ratio is low, and when it exceeds 0.8, the shrinkage rate tends to be low.

[0011] The PET resin film can be obtained by a known inflation molding method or extrusion molding method. In the case of the inflation molding method, a film with a desired stretching ratio can be obtained by setting a specific take-up speed. In the case of extrusion molding, the resin is extruded using an extruder, and the film-like material discharged from the lip port is rapidly cooled to obtain an amorphous unstretched film. The obtained unstretched film is stretched to a specific stretching ratio by a known stretching method. The stretched film is heat-set at a specific temperature to obtain the dry battery jacket film of the present invention.

An example of the manufacturing method will be explained using an extrusion molding method as an example.

[0013] PET resin is extruded using an extruder equipped with a T-die, and the film-like material discharged from the lip port is rapidly cooled to 60 to 80°C using a chill roll to obtain an amorphous unstretched film. . The rapid cooling may be performed by an air cooling method using an air ring.

The amorphous unstretched film is stretched at a stretching ratio of 1.5 to 3.0 in the machine direction (MD) using a known roll stretching machine.
It is stretched by 2 times, preferably 2.0 to 2.5 times. If the stretching ratio is less than 1.5 times, no heat shrinkage rate (especially in the stretching direction) can be achieved, and even if it exceeds 3.0 times, no heat shrinkage rate can be achieved. That is, when the film is stretched in a temperature range of -5° C. to glass transition temperature +10° C., when the stretching ratio is out of the above range, the heat shrinkage rate decreases.

The stretching temperature is the glass transition temperature of the film -
The range of 5°C to glass transition temperature +10°C is preferable. Temperatures lower than the glass transition temperature of -5°C cause stretching breakage,
In the case of roll stretching, when the glass transition temperature exceeds +10℃,
The film becomes easier to wrap around the roll.

[0016] The uniaxially stretched film has a temperature of 80 to 10
Heat setting is carried out at 0°C, preferably 85-95°C. If the heat-setting temperature is less than 80°C, heat shrinkage tends to occur during secondary processing, and if the temperature exceeds 100°C, the film tends to wrap around heat-setting rolls when the stretching ratio is low.

[0017] The thickness of the film used in the present invention is 30~
It is 70 μm, preferably 35 to 60 μm. 30μm
If it is less than that, the strength will be weakened, problems will occur during secondary processing, and the image of metalization will not be realized. 70μ
If it exceeds m, the cost will increase and the difference in thickness from the metal will become small, which is not suitable for the present invention, which aims to increase the internal capacity of the battery.

It is also possible to add other suitable additives to the PET resin as long as they do not adversely affect the properties of the film according to the invention. Examples of additives include polyolefin resins, antistatic agents, stabilizers, lubricants, and nucleating agents. 0.1-1% by weight, preferably 0.2-0.6% by weight, especially to improve processing capacity
It is also possible to add organic or inorganic anti-blocking agents. Examples of the organic anti-blocking agent include polymers that are incompatible with PET resin, such as polypropylene and polyethylene. Examples of inorganic anti-blocking agents include:
Examples include magnesium oxide and magnesium salts. Especially preferred is magnesium stearate.

The obtained jacket film for dry batteries is subjected to aluminum vapor deposition, printing, etc. to give it a metal appearance, and then a thermosetting adhesive is applied to the film, and the film is labeled and passed through a shrink tunnel. Shrink the top and bottom to use as the outer packaging material for the dry battery.

[0020] The shrunk portions of the upper and bottom parts produce a bending effect, and an outer envelope effect similar to that of a metal jacket can be obtained.

[0021]

[Examples] The present invention will be explained in more detail with reference to Examples below. Examples 1 to 7, Comparative Examples 1 to 4 100 parts by weight of PET resin (J-125 manufactured by Mitsui Pet Co., Ltd.) having the IV values shown in [Table 1], 0.02 parts by weight of silicon oxide powder and stearin Magnesium acid 0.
1 part by weight was added and mixed, and an extruder equipped with a slot die was used at a resin temperature of 250°C and a die lip opening of 0.3~
It was extruded at 0.7 mm.

The extruded film material was rapidly cooled using a chill roll set at 65° C. to obtain an unstretched film. The resulting unstretched film has a surface temperature of 80 to 85°C.
After preheating on a hot roll set to
MD) direction. The stretched film was passed over a hot roll set at 90° C. and heat-set under tension. The shrinkage rate of the obtained film is shown in [Table 1].

[0023] After applying a thermosetting adhesive to the films obtained in the practical evaluation examples and comparative examples, the films were labeled, and then passed through a shrink tunnel to shrink the top and bottom of the dry batteries. Use as outer packaging material.

Table 1 shows the physical properties of the obtained film and its condition when used as an outer package for a dry battery.

[0025]

[Table 1]

[0026]

Effects of the Invention: By using the jacket film for dry batteries of the present invention, it can be wrapped in the same way as a metal jacket, and since the film is approximately 1/4 as thick as metal, it has the same outer diameter as a metal jacket. In the case of dry batteries, the internal capacity of the battery can be increased, which has great industrial value.

Claims (2)

[Claims] 1. A film made of polyethylene terephthalate resin having an intrinsic viscosity of 0.6 to 0.8,
Thermal shrinkage after being left in an oven at 100°C for 15 minutes is 30% or more in the stretching direction and 10% in the direction perpendicular to it.
A jacket film for dry batteries characterized by the following: 2. A film made of a polyethylene terephthalate resin is unidirectionally expanded by 1.5 to 3.0 times the unstretched film in a temperature range of -5°C to the glass transition temperature of the film +10°C. The dry battery jacket film according to claim 1, characterized in that it is uniaxially stretched.