Source: Link Testing Instruments Co.,Ltd.
Laundry liquid is currently a popular daily chemical product. Because of its mildness, non-irritation, easy rinsing, and low environmental pollution, it is gradually replacing soap and washing powder, and has become the leading product in the laundry detergent market. Soft plastic composite film packaging bag is one of the main packaging forms of laundry liquid, and its materials include PET/PA/PE, PET/PA/Al/PE, etc. Compared with other products, the weight of laundry liquid in unit packaging is usually relatively large. In order to prevent bag breakage during circulation, the materials used for packaging laundry liquid should have high impact resistance.
At present, China testing methods for the impact resistance of flexible plastic packaging materials include the free-falling dart method and the pendulum impact method. The former uses the weight of the falling dart breaking through the film to represent the impact resistance of the material, while the latter uses the energy lost to break through the film to represent the impact resistance of the material. Since the thickness of laundry detergent packaging is usually thicker and the impact resistance is higher, this test uses the free-falling dart method for testing.
Test Methods and Instruments
The method standard on which this test is based is GB/T 9639.1-2008 "Plastic Film and Sheet Impact Resistance Test Method Free Falling Dart Method Part 1: Step Method", which is applicable to plastic film and sheet with a thickness of less than 1 mm. The test instrument uses the LTMC-A dart impact tester independently developed and produced by Link Testing Instruments Co., Ltd. to test the impact resistance of the samples.
Test principle: The basic principle of this test is to obtain the minimum weight of the dart that breaks through the sample through a series of impact tests on the sample. The realization process is to fix the sample in the equipment fixture, release the falling dart, according to the damage of the sample (if the sample is damaged, reduce the weight of the falling dart by Δm, if the sample is not broken, increase the weight by Δm), increase or decrease the weight of the falling dart, then impact the sample again, and so on, repeat the impact test. When the test of 20 samples is completed, calculate the number N of damaged samples. If N is equal to 10, the test is completed; If it is greater than 10, it is still necessary to continue to supplement the sample test so that the number of undamaged samples is 10. Then the equipment automatically calculates and displays the impact damage mass of the sample according to the calculation formula in the standard.
Test sample and test process
Test sample: plastic composite film for a certain brand of laundry liquid packaging.
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, select the test method (method A or method B), choose method A for this test, adjust the falling height of the falling dart to 0.66 ± 0.01 m accordingly, adjust the adjustable support of the equipment so that the falling dart can impact the center of the sample after falling, and choose a falling dart with a head diameter of 38 mm.
3. Clamping the sample - take a piece of tailor-made sample and put it on the lower fixture to ensure that 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. According to the damage situation, determine the approximate impact damage weight.
5. Test——Insert the falling dart of this quality into the magnetic connector vertically, click the test option, and the falling dart will automatically drop the impact sample. Input the damage status of the sample into the equipment, then increase (subtract) the weight of the falling dart, repeat the clamping of the sample-installation of the dart-test-record the calculation of the sample damage, until the number of damaged or undamaged samples reaches the unknown, the equipment automatically calculates and displays the impact damage quality.
Test Results and Analysis
The impact damage mass of the plastic composite film sample for packaging tested is 537.1 g.
Impact resistance is one of the important factors that determine whether soft plastic materials can be used in laundry liquid packaging. Strengthening the detection of impact resistance of packaging is of great significance to reduce the rate of package breakage. In this paper, the free-falling dart method is used to test the impact damage quality of soft plastic packaging samples of a certain brand of laundry detergent. The test process is relatively simple, the equipment is easy to operate, and the degree of intelligence is high, which can accurately reflect the impact resistance of the tested samples.
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