Source: Link Testing Instruments Co.,Ltd.
Laundry detergent is currently a popular daily chemical product. Due to its advantages such as mildness, non-irritation, easy rinsing, and low environmental pollution, it is gradually replacing soap and washing powder and becoming the leading product in the clothing detergent market. Soft plastic composite film packaging bags are one of the main packaging forms of laundry detergent. The materials include PET/PA/PE, PET/PA/Al/PE, etc. Compared with other products, the weight of laundry detergent in a unit package is usually larger. In order to prevent the bag from breaking during the circulation process, the materials used to package laundry detergent are required to have high impact resistance.
At present, domestic testing methods for the impact resistance of soft plastic packaging materials include the free falling dart method, the pendulum impact method, etc. The former uses the weight of the falling dart that breaks through the film to indicate the impact resistance of the material, while the latter uses the breaking The energy lost by the film represents the impact resistance of the material. Since laundry detergent packaging is usually thicker and has higher impact resistance, the free falling dart method was used in this test.
Test methods and instruments
The method standard based on this test is GB/T 9639.1-2008 "Test Method for Impact Resistance of Plastic Films and Sheets - Free Falling Dart Method Part 1: Cascade Method", which is applicable to materials with thickness less than 1mm plastic films and sheets. The test instrument uses the LTMC-A falling dart impact tester independently developed and produced by Link Testing Instruments Co.,Ltd. to test the impact resistance of the sample.
The LTMC-A falling dart impact tester is suitable for measuring the impact mass and energy of plastic films or sheets when 50% of the plastic film or sheet samples are damaged under the impact of free falling darts from a given height.
Test principle: The basic principle of this test is to conduct a series of impact tests on the sample to obtain the minimum falling dart weight that breaks through the sample. The implementation process is to fix the sample in the equipment fixture and release the falling dart. According to the damage of the sample (if the sample is damaged, the weight of the falling dart will be reduced by Δm, if the sample is not broken, the weight of the falling dart will be increased by Δm). After increasing or decreasing the mass of the falling dart, impact the sample again, and so on, repeat the impact test. When 20 trials is completed, calculate the number N of damaged samples. If N is equal to 10, the test is completed; If N is less than 10, continue to add samples for testing until N equals 10; if N is greater than 10, continue to add samples for testing so that the number of undamaged samples is 10. Then the equipment automatically calculates and displays the impact damage quality of the sample according to the calculation formula in the standard.
Test samples and test process
Test sample: Plastic composite film for packaging of a certain brand of laundry detergent.
1. Cutting samples - Cut at least 20 pieces of 18 cm × 18 cm samples from the surface of the laundry detergent packaging bag sample to be tested.
2. Adjust the instrument - turn on the instrument switch and select the test method (Method A or B). For this test, choose Method A. Correspondingly, adjust the falling height of the falling dart to 0.66 ± 0.01 m. Adjust the adjustable bracket of the equipment so that The falling dart can impact the center of the sample after falling, so choose a falling dart with a head diameter of 38 mm.
3. Clamp the sample - take a piece of cut sample and place it on the lower clamp, make sure the surface of the sample is flat, step on the foot switch, and the equipment will automatically clamp the sample.
4. Pre-test - Install a falling dart of a certain weight and release it. Based on the damage situation, determine the approximate impact damage weight.
5. Test - Insert the falling dart of this mass vertically into the magnetic connector, click the test option, and the falling dart will automatically fall and impact the sample. Input the sample damage status into the equipment, then increase (decrease) the weight of the falling dart, and repeat clamping the sample - installing the falling dart - testing - recording the sample breakage situation until the number of damaged or undamaged samples reaches the unknown requirement, the device automatically calculates and displays the impact damage mass.
Test results and analysis
The impact damage mass of the plastic composite film sample for laundry detergent packaging tested this time was 537.1 g.
Impact resistance is one of the important factors that determine whether soft plastic materials can be used for laundry detergent packaging. Strengthening the testing of packaging impact resistance is of great significance to reduce the rate of packaging bag breakage.
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