Return list

Testing method for heat-sealing strength of plastic composite film packaging of frozen products

Jul 25,2021

Source: Link Testing Instruments Co.,Ltd.

Heat-sealing strength, also known as heat-sealing strength or sealing strength, is an index for evaluating the sealing strength of heat-sealed parts of food packaging. If the heat-sealing effect is significantly stronger than the composite fastness, the heat-sealed parts are likely to be difficult to unpack. If the heat sealing strength is insufficient, the finished package will have problems such as openings, air leakage, and bag breakage.

Frozen products include frozen bread, frozen fried rice, frozen cheese, frozen desserts, flower rolls, spring rolls, etc., and are generally packaged with plastic composite film. If the sealing strength of the quick-frozen product packaging is insufficient, air leakage or bag breakage may occur, resulting in poor taste of the quick-frozen product , And even breed bacteria, threatening the health of consumers. Therefore, the packaging of quick-frozen products in food enterprises should have reasonable heat sealing strength to ensure the sealing performance of the product packaging.

Test methods and test equipment

   The domestic testing standards for the heat-sealing strength of plastic film packaging bags mainly refer to QB/T 2358-1998 "Test Method for Heat-sealing Strength of Plastic Film Packaging Bags". Link Testing intelligent electronic tensile tester LTS-05 can be used for testing.

Test principle: The sample is clamped between the two chucks of the fixture, and the two chucks move relative to each other. The force value during the test is collected through the force sensor located on the movable chuck and the displacement sensor built in the machine Change and displacement change, so as to calculate the performance indicators such as heat seal strength, tensile strength, deformation rate, and peel strength of the sample.

Auto Tensile Tester LTS-05

Test sample and test process

Test sample: composite film packaging of quick-frozen products provided by a food factory.

Experimental procedure:

(1) Cut 10 sample strips with a width of 15 mm and an unfolded length of 100 mm from the three heat-sealed edges of the sample bag.

(2) Set parameter information such as sample width and test speed.

(3) Clamp the two ends of the sample strip on the two clamps respectively, and the long axis direction of the sample strip should coincide with the center line of the two clamps.

(4) Click the start test option to start the test. The instrument automatically records the force value during the test and calculates the test result.

Test results and analysis

   The test results are: the average heat seal strength of the upper edge seal is 22.145 N/15mm, the average value of the heat seal strength of the lower edge seal is 23.114 N/15mm, and the average value of the heat seal strength of the side seal edge is 11.256 N/15mm.

For more details of tensile tester LTS-05 and Link Testing please visit

Live Chat