Source: Link Testing Instruments co.,Ltd.
Aluminized BOPP tape is an ideal supporting protective layer for the new generation of thermal insulation, heat insulation, and sound insulation building materials. It can partially replace aluminum foil tape and is used as the outer wrapping material for insulation layers such as heating and cooling equipment and pipes, as well as for heat insulation and sound insulation veneers on roofs. Moisture-proof, mildew-proof, anti-corrosion, etc. of materials and equipment. The water vapor barrier performance is an important factor that affects whether the aluminized BOPP tape can meet the above purposes. Taking the moisture-proof and mildew-proof equipment as an example, if the water vapor transmission rate of the aluminized BOPP tape is large, it will be resistant to water in the environment. If the barrier properties of vapor are poor, more water vapor will penetrate into the inside of the tape, causing the equipment to become rusty, moldy, etc. due to the large amount of moisture it comes into contact with. Therefore, the water vapor barrier performance of aluminized BOPP tape is one of the properties that relevant companies should focus on monitoring. This article analyzes the water vapor barrier performance by testing the water vapor transmittance of aluminized BOPP tape.
Test methods and instruments
At present, there are four main methods for testing the water vapor transmission rate of materials: cup method, electrolysis method, infrared method and humidity method. Among them, the cup method is divided into weight gain method and weight loss method. The test in this article is based on the weight gain method specified in GB/T 15331-1994 "Test Method for Water Vapor Transmittance of Pressure-Sensitive Adhesive Tapes".
The instrument and equipment used in the test is the LTWTC-203H water vapor transmission test system developed and produced by Link Testing. The LTWTC-203H water vapor transmission rate test system is suitable for measuring the water vapor transmission rate of various materials such as plastic films, composite films, and medical and construction fields. Through the measurement of water vapor transmission rate, the technical indicators of controlling and regulating packaging materials and other products can be achieved.
Test principle: The weight gain method calculates the water vapor transmission rate of the sample based on the increase in weight of the moisture-permeable cup. The specific implementation process is to place a desiccant in the moisture-permeable cup, seal the sample at the mouth of the moisture-permeable cup, and control the humidity in the test chamber of the equipment to form a certain humidity difference on both sides of the sample, allowing water vapor to pass through the test chamber. The sample penetrates into the moisture-permeable cup to provide power. The water vapor that penetrates into the moisture-permeable cup is absorbed by the desiccant, causing the weight of the moisture-permeable cup to change. By testing the increase in the weight of the moisture-permeable cup over time, the water vapor transmission rate of the sample is obtained.
Test samples and test process
Test sample: a certain brand of aluminized BOPP tape.
(1) Cut three samples with a diameter of 74 mm from the surface of the aluminized BOPP tape sample.
(2) Put a certain amount of dried anhydrous calcium chloride into the moisture-permeable cup as the desiccant, and seal the three cut samples on three moisture-permeable cups that already contain the desiccant.
(3) Place the moisture-permeable cups with specimens clamped on the moisture-permeable cup holders in the test chamber of the equipment, and close the test chamber door.
(4) In the system software part, set parameter information such as sample thickness, test temperature and humidity (38°C, 90%RH), test time interval, etc., click the test option, and the test starts. The equipment automatically tests the weight of the moisture-permeable cup at set time intervals, and calculates and displays test results such as the water vapor transmission rate of the sample based on the test data.
Test results and analysis
The water vapor transmission rate test values of the three samples are: 3.4478 g/(m2·24h), 3.4215 g/(m2·24h), 3.4589 g/(m2·24h).
The entire test process is simple to operate and the equipment is highly intelligent. From the above test results, it can be seen that the water vapor transmission rate test results of the aluminized BOPP tape sample are more uniform, indicating that the moisture barrier properties of each part of the sample are uniform.
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