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How to test the shrinkage properties of shrink film used for bottled water?

Apr 09,2021

Source: Link Testing Instruments Co., Ltd

Shrink wrap, also shrink film, is a material made up of polymer plastic film. When heat is applied, it shrinks tightly over whatever it is covering. It is very common to see shrink film is used to pack bottled drinks such as beers, mineral water and beverage, etc. Such kind of packaging is featured with good flexibility, tear resistance, impact resistance and durability. Common raw materials used for shrink films include PE, POF and PET, etc.

The shrinkage properties of shrink film may directly influence the performance of the packaging. Those properties include shrinkage ratio, shrinking force, contracting force. To be specific, if the shrink film is low in shrinkage ratio, shrinking force and contracting force, it may not be able to cover the goods tightly. On the other hand, if the shrinkage ratio, shrinking force and contracting force of the shrink film is too high, the goods within the packaging may be deformed due to the compression caused by the shrink film.

Figure 1. Shrink Film used in Bottled Drinks

Therefore, proper shrinkage properties are important to the shrink packaging for bottled drinks and it is necessary for the manufacturers to test the shrinkage properties of the shrink films before use. This article provides a test method of the shrinkage properties of shrink film for your reference. The test specimen we used are shrink films used for one brand bottled mineral water and the testing instrument we used for the tests is Link Testing LTRSY-03 Film Thermal Shrinkage Tester.

Thermal Shrinkage Tester LTRSY-03

The LTRSY-03 Thermal Shrinkage tester conforms to ISO 14616.

The tests should be performed according to the following procedures.

1.Cut six pieces of specimens from the machine direction and transverse direction respectively. The specimen width should be 15mm. Make two holes in the two ends of the specimen with special hole puncher. The distance between the two holes should be 100mm.

2.Divide those specimens into three groups, one from machine direction and one from transverse direction for each group. For each group, one is used for shrinking force and contracting force tests, the other one is used for shrinkage ratio test.

3.Set test temperature, end temperature and other test parameters. Click Start Test to heat the oil.

4.After the temperature reach the setting value. Clamp one group of specimens in the sample grip net. Then put the specimens into the oil bath.

5.Repeat the operations of step 3 and 4 until all the specimen tests are finished.

Then we can calculate the shrinkage rate of the specimen on different direction

For more details about LTRSY-03 Film Thermal Shrinkage Tester, please visit

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