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

Source: Labthink 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.
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 Labthink’s FST-02 Film Thermal Shrinkage Tester.


Labthink’s FST-02 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) Clamp one group of specimens in the sample grips with load cell and displacement sensor. Keep the specimens straight.


(4) Set test temperature, end temperature and other test parameters. Click Start Test to start the tests.
(5) When the preset temperature of heatingchamber is reached, the specimen will enter the heating chamber automatically. The system starts countdown, records and displays the real-time force values and displacement changes. When the test is finished, the heating chamber stops heating and the specimen will be sent out of the heating chamber. The contracting force will be measured.
(6) When the test is finished, the maximum shrinking force, maximum contracting force and maximum shrinkageratio will be displayed automatically.
(7) Repeat the operations of step 3 to step 6 until all the specimen tests are finished.
(8) The test results of the specimen for machine direction and transverse direction should be the average values of the three groups of the results.
For more details about FST-02 Film Thermal Shrinkage Tester, please visit www.labthink.com
About Labthink Instruments Co., Ltd:
Labthink Instruments Co., Ltd is one leading supplier of packaging testing instruments, which is headquartered in Jinan, China and operated in Boston, U.S.A.

Labthink is a multinational technology company that is devoted to helping customers succeed, employees grow and brands gain respect. The headquarters of Labthink is in Jinan, China; its international headquarters is in Boston, USA; and its SAC IT Center is in Hong Kong, China. The company has more than 50 international distributors and more than 30 international service providers.

Labthink International, Inc.
200 River's Edge Drive, Medford, MA, 02155, USA
Phone: (+1) 617-830-2190
FAX: (+1) 781-219-3638
Email: sales@labthink.com

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