JPS5864958A - Heat-shrinkable film and method for heat-shrinkable packaging of articles using the heat-shrinkable film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-shrinkable film and a method for heat-shrink packaging articles using a nuclear heat-shrinkable film.

- The heat-shrink packaging method for products involves wrapping the product in a heat-shrinkable film and then shrinking the heat-shrinkable film by heating.
This is a method of wrapping a heat-shrinkable film in close contact with an article.

Conventionally, heat-shrinkable packaging methods have used heat-shrinkable films made of polyvinyl chloride, heat-shrinkable films made of polypropylene, heat-shrinkable films made of polyethylene, and the like. However, heat-shrinkable films made of polyvinyl chloride pose problems in terms of safety as food packaging, and also have drawbacks in fusing seal strength, low-temperature strength, and the like. In addition, polypropylene heat-shrinkable films have drawbacks in low-temperature shrinkability, gloss, and low-temperature strength, while polyethylene heat-shrinkable films have low cohesive strength after shrinkage, poor shrinkage, and lack transparency. There are drawbacks such as low strength.

The present invention was made to eliminate such drawbacks, and involves uniaxially stretching an amorphous polyethylene terephthalate film or sheet to 1.5 to 4.5 times at a temperature above the glass transition point and below 100°C. Alternatively, the present invention relates to a heat-shrinkable film characterized in that the reorientation stress is increased by 10 to 70 by biaxial stretching.

Furthermore, the present invention provides a thermal packaging method for articles in which the heat-shrinkable film is wrapped with a heat-shrinkable film and then the heat-shrinkable film is shrunk by heating. t5~ at a temperature above the glass transition point and below 100℃
By uniaxially or biaxially stretching 4.5 times, the orientation return stress can be increased to 10 to 70 kl? The present invention relates to a method for heat-shrinkable packaging of articles, characterized by using a heat-shrinkable film having a thickness of 1.5 cm.

The heat-shrinkable film according to the present invention has a high heat-shrinkage rate,
Cohesive strength, #1: It has excellent sealing strength, transparency, gloss, rigidity, printability, low-temperature strength, and safety as food packaging, so it can be used extremely well for heat-shrink packaging of goods. .

Amorphous polyethylene terephthalate is a combination of ethylene glycol and terephthalic acid or dimethylene terephthalate.
It is modified with isophthalic acid, 1,4-cyclohexane dimetatool, etc. when reacting with ester, and does not become cloudy even when heated gradually and does not have a melting point.

Examples of amorphous polyethylene terephthalate include Eastman Chemical Co. gPETG6765.

The stretching temperature in the present invention can be varied considerably within the range that results in molecular orientation. As the stretching temperature approaches the glass transition temperature, the stretching tension increases and stretching unevenness tends to occur, so it is preferably 6 to 5° C. higher. If the stretching temperature exceeds 100°C, uneven thickness may occur.

Therefore, the stretching temperature may be higher than the glass transition point and lower than 100°C, preferably 85 to 95°C.

The stretching ratio in the present invention may be 15 to 4.5 times, preferably 2.5 to 4.0 times. When the stretching ratio is less than 15 times, the heat shrinkage rate is low and a uniform thin film cannot be obtained. Furthermore, when the stretching ratio is greater than 45 times, whitening occurs and transparency is lost.

The reorientation stress of the heat-shrinkable film is 10 to 70 Yu/cm
If the reorientation stress is less than 10, the binding force after heat shrinkage will be poor.Also, if the reorientation stress is less than 70 kg/a If it is large, whitening occurs and transparency is lost.

To heat shrink wrap an entire article using the heat shrinkable film of the present invention, wrap the entire article in a heat shrinkable film with appropriate holes in the same way as in normal heat shrink packaging.
After the edges of the stacked heat-shrinkable films are heated or bonded with an adhesive, the heat-shrinkable film may be heated and shrunk by passing it through a heat-shrinking tunnel configured with a chamber for circulating hot air. . In addition, in order to heat-shrink wrap cylindrical surfaces such as bottles and cans using the heat-shrinkable film according to the present invention, it is necessary to wrap the ends of the overlapping heat-shrinkable films in the same way as in normal heat-shrink packaging. The cylindrical heat-shrinkable film is made into a cylindrical shape by heating or adhesive bonding, and the cylindrical surface of a bottle, can, etc. is wrapped with a cylindrical heat-shrinkable film, and then the heat-shrinkable film is heated by passing it through a heat-shrinking tunnel. Just let it shrink. The heating temperature of the heat shrinkable film in the heat shrink tunnel is preferably 140 to 180°C,
Further, the heating time of the heat-shrinkable film is preferably 1 to 5 seconds.

Next, how will the present invention be concretely explained by examples? & Clarify.

Example 1 A sheet having a thickness of α13IllI was manufactured by extruding amorphous polyethylene terephthalate (IIIPETG 6765 from Eastman Chemical Co.) using an extruder, and then a sheet with a stretching temperature of 90°C and a stretching ratio of 15 was produced using a stretching device.
Double, 2.0 times, 2.5 cans! h, 0x, 4x, 5x 〒
Perform axial stretching to create an island-like film! ll! I tried it. Next, the obtained heat-shrinkable film was heated to 70°C and 80°C.
The samples were immersed in warm water at 100°C for 5 minutes, and the heat shrinkage rate in one direction of elongation was determined.

Table 1 shows the heat shrinkage rate and orientation return stress of each heat-shrinkable film.

Table 1 From Table 1, the heat shrinkable film according to the present invention has an excellent heat shrinkage rate of 15!, which is suitable for heat shrink packaging. You can see that it can be used.

Example 2 Amorphous polyethylene terephthalate (Eastman Chemical Co. 11PETG6765) was extruded using an extruder to form a sheet with a thickness of 0.13 m! After stretching, the film was biaxially stretched 6 times in the length and 5 times in the width using a stretching device at a stretching temperature of 88°C, so that the orientation return stress in the machine direction was 48 kl/c.
/, 50 kcy/eta in the lateral direction, and a heat-shrinkable film with excellent transparency and a thickness of 15 microns.

The obtained heat-shrinkable film is immersed in water, and gradually
When heated to 00°C, the heat shrinkage start temperature was 58°C, the heat shrinkage rate in the inner direction was 65%, and the heat shrinkage rate in the transverse direction was 67%, indicating that it can be suitably used for heat shrink packaging.

Example 3 Amorphous polyethylene terephthalate (PETG 6765 manufactured by Eastman Chemical Co.) was extruded using an extruder to produce a sheet with a thickness of α15m1I+, and then a stretching device was used to stretch at a stretching temperature of 90°C and a stretching ratio. A highly transparent heat-shrinkable film with an orientation return stress of 50'Kll/d was formed by uniaxial stretching and pressing at a magnification of 5.0 times. Next, the obtained heat-shrinkable film was heated to 60°C, 70°C, 80°C, and 90°C.
The sample was immersed in warm water for KS minutes, and the heat shrinkage rate in the stretching direction was determined.

The results of Section 7 are shown in Table 2.

Table 2 Table 2 shows that the heat shrinkable film according to the present invention has an excellent heat shrinkage rate and can be suitably used for heat shrink packaging.

Example 4 Amorphous polyethylene terephthalate (Eastman Chemical Co., Ltd. GPG'RC 6765) was extruded using an extruder to produce Sinito, and then a stretching device was used to stretch at a stretching temperature of 90° C. to 28 times the length and 2 times the width. Two wheels are stretched 8 times and the orientation return stress is 40 k+//c in the longitudinal direction and 45 in the transverse direction.
A highly transparent heat-shrinkable film having a thickness of 15 μm/kg/xζ was formed. .

A PW-R2-TF450 packaging machine manufactured by Tokiwa Industries Co., Ltd. is used to wrap five plastic containers containing lactic acid beverages lined up horizontally in a heat-shrinkable film, and heat the edges of the overlapped heat-shrinkable films. After sealing, the heat-shrinkable film was passed through a heat-shrink tunnel and heated at 145° C. for 3 seconds to heat-shrink it, resulting in a package with excellent gloss and strong cohesion.

Example 5 A sheet was manufactured by extruding amorphous polyethylene terephthalate (PETG6763 manufactured by Eastman Chemical Company) using an extruder, and then uniaxially stretched to 2.8 times using a stretching device at a stretching temperature of 85°C. Orientation return stress 55 h
/am-A highly transparent heat-shrinkable film having a thickness of 45 microns was formed.

The ends of the heat-shrinkable film in the stretching direction are overlapped and attached with adhesive to form a cylindrical shape with a diameter of 70M, Fuji Seal,
[: A bottle with a diameter of 671 II was wrapped in a cylindrical heat-shrinkable film using a shrink label machine manufactured by our company, passed through a heat-shrink tunnel, and heated at 160°C for 6 seconds to shrink the island-like dark blue film. By the way, I was able to wrap it beautifully with the cylindrical surface of the bottle.

Claims (1)

[Claims] A heat-shrinkable film or a linear heat-shrinkable film is used. An amorphous polyethylene terephthalate film or sheet is heated at a temperature above the glass transition point and below 100°C for 15 to 10 minutes.
A heat-shrinkable film or lumen characterized in that the orientation return stress is increased from 10 to 70 times by biaxial stretching or biaxial stretching by 4.5 times. 2. In a heat-shrinkable packaging method for an article, which involves wrapping the article in a heat-shrinkable film and then shrinking the heat-shrinkable film by heating. As a heat-shrinkable film, use an amorphous polyethylene terephthalate film or 7-T film at 100°C above the glass transition point.
Heat-shrinkable packaging for articles characterized by using a heat-shrinkable film that has been uniaxially or biaxially stretched 15 to 4.5 times at the following temperature to have an orientation return stress of 10 to 70 degrees. Method.