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Test method for heat sealing performance of the bottom of packaging bags

Jan 20,2022

Source: Link Testing Instruments Co.,Ltd.

Packaging bags are indispensable portable objects in people's daily life, and are often used to hold other items. It is widely used because of its advantages of low cost, extremely light weight, large capacity and easy storage, but it is banned by some countries due to the shortcomings of extremely long degradation cycle and difficult disposal of plastic bags. In order to reduce the pollution of plastic bags to the environment, the reuse rate of packaging bags should be increased to reduce the production volume of plastic bags. The firmness of the bag body is the key to ensuring repeated use, especially the sealing performance of the bottom of the plastic bag. Therefore, plastic bag manufacturers should strengthen the heat-sealing strength test at the bottom of the plastic bag, evaluate the sealing performance of the bottom of the bag in time, and prolong the service life of the plastic bag.

If the heat sealing strength at the bottom of the packaging bag is low, it is easy to cause problems such as cracking and leakage at the seal and cannot be reused. There is a problem of root cutting at the seal, which causes the package to leak at the root of the heat seal, or even break the bag. To sum up, manufacturers should attach great importance to the detection of heat sealing strength of packaging bags.

Test methods and instruments

The domestic test standard for heat sealing strength of plastic film packaging bags mainly refers to QB/T2358 "Test method for heat sealing strength of plastic film packaging bags". This test uses the LTS-05 independently developed and designed by Link Testing Instruments Co., Ltd.

Auto Tensile Tester LTS-05

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

Test samples and test procedures

Test sample: a vest-style plastic bag sample provided by a company.

Experimental procedure:

(1) Use a sample cutter to cut 10 sample strips with a width of 150 mm and a length of 100 mm from the bottom of the plastic bag.

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

(3) Set parameters such as test speed and sample width.

(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 heat sealing strength of the edge sealing of the plastic bag samples in this test are: 7.619 N/15mm, 7.882 N/15mm, 8.257 N/15mm, 8.323 N/15mm, 8.554N/15mm. For more details please visit

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