Source: Link Testing Instruments Co.,Ltd.
Potato chips contain a large amount of oil. When encountering high concentrations of oxygen, the oil is easily oxidized, causing the potato chips to smell bad. In order to reduce the penetration of oxygen in the environment into the inside of the potato chip packaging, food companies generally use aluminized materials with higher barrier properties. Composite film for packaging. Aluminized composite film refers to the evaporation of aluminum on one of the single-layer films. The presence of metallic aluminum increases the overall barrier performance of the material, but also results in poor rubbing resistance of the material. When rubbed by external forces, the evaporated aluminum layer It is prone to brittleness, creases, pinholes, etc., which causes the overall barrier properties and physical and mechanical properties of the packaging to decline, failing to meet the expected values, causing the potato chips to become non-crisp, smell, etc. during the shelf life. Therefore, by testing and comparing the barrier properties of aluminized composite film packaging before and after rubbing, the rubbing resistance of the packaging can be effectively controlled to prevent the above quality problems of potato chips caused by poor rubbing resistance of packaging materials.
Test methods and instruments
Domestic testing methods for oxygen permeability of soft plastic composite film materials include the coulometer method (i.e., isobaric method) and the differential pressure method. The reference method standards are GB/T 1038-2000 "Plastic Film and Sheet Gas Permeability Test". Method: Pressure Differential Method" and GB/T 19789-2005 "Packaging Materials Plastic Films and Sheets Oxidation Permeability Test Coulombo meter Detection Method". The reference standard in this article is GB/T 1038 Pressure Differential Method.
At present, there are no testing standards for packaging rub performance in China. The test in this article refers to ASTM F392 "Test Method for Flexural Durability of Flexible Barrier Materials" to simulate the production, processing, transportation and other processes of aluminized composite films. Conduct a rubbing test on the test sample if it may be subjected to rubbing, crushing damage and other behaviors.
This test used the RCT-02 Flex durability tester and GTC-203H differential pressure Gas permeability tester independently developed and produced by Link Testing Instruments Co.,Ltd.
Test samples and test process
Test sample: Aluminized composite film packaging of potato chips provided by a food company.
Experimental procedure:
(1) Sample preparation process:
Use a sampler to cut 3 pieces of Φ97 mm specimens from the potato chip aluminized composite film sample to test their oxygen transmittance.
Take another potato chip aluminized composite film sample, cut 3 samples with a length of 280 mm and a width of 200 mm, and fix the samples on the RCT-02 rubbing tester with a 10 ~ 12 mm wide pressure-sensitive double-sided tape. Select Experiment with suitable rubbing patterns. Use a sampler to cut 3 pieces of Φ97 mm specimens from the rubbed specimen to test the oxygen transmittance.
(2) Clamp the three samples before rubbing in the test chamber of the GTC-203H differential pressure gas permeability tester for testing.
(3) First set the sample name, sample thickness, test temperature, test humidity and other parameters on the differential pressure gas permeability meter.
(4) Start the vacuum pump.
(5) Click the "Start Test" option to start the test, and the instrument automatically calculates and displays the test results.
(6) After rubbing, the three samples are tested according to the steps (2) ~ (5) in sequence, and the changes in the average oxygen transmittance of the samples before and after rubbing are compared.
Test results and analysis
The average oxygen transmission rate of the samples tested this time before rubbing was 0.4712 cm3/(m2·24h·0.1MPa); after rubbing, the average oxygen transmission rate was 23.4785 cm3/(m2·24h·0.1MPa). From the above results, it can be seen that the oxygen permeability of the aluminized composite film of potato chips after rubbing increases significantly and the oxygen barrier property decreases. The rubbing resistance of the aluminum-plated composite film can be improved by increasing the bonding fastness between the aluminum-plated layer and its base film, increasing the thickness of the aluminum-plated layer, etc., and promptly inspecting the oxygen permeability of the aluminum-plated composite film packaging before and after rubbing.
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