Source: Link Testing Instruments Co.,Ltd.
Aluminum-coated 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 be used as the outer wrapping material for the insulation layer of heating and cooling equipment, pipes, etc., as well as the thermal insulation and sound insulation veneer materials of the roof and the moisture-proof, mildew-proof, and anti-corrosion properties of the equipment. The water vapor barrier performance is an important factor affecting whether the aluminum-coated BOPP tape can meet the above-mentioned purposes. Taking the moisture-proof and mildew-proof properties of the equipment as an example, if the water vapor permeability of the aluminum-coated BOPP tape is large, that is, the barrier property to water vapor in the environment is poor, more water vapor will penetrate into the tape, causing the equipment to rust and mold due to contact with more moisture. Therefore, the water vapor barrier performance of the aluminum-coated BOPP tape is one of the key performances that relevant companies should monitor. This article analyzes its water vapor barrier performance by testing the water vapor permeability of the aluminum-coated BOPP tape.
Test methods and instrument
Currently, there are four main test methods for water vapor permeability 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. This test is based on the weight gain method specified in GB/T 15331-1994 "Test method for water vapor permeability of pressure-sensitive adhesive tapes" and ISO 2528:2017 "Sheet materials — Determination of water vapour transmission rate (WVTR) — Gravimetric (dish) method"
The instrument used in the test is the LTWTC-203H water vapor permeability test system developed and produced by Link Testing. The LTWTC-203H water vapor permeability test system is suitable for the determination of water vapor permeability of various materials such as plastic films, composite films, medical and construction fields. By measuring the water vapor permeability, the technical indicators of products such as packaging materials can be controlled and adjusted.
Test principle: The weight gain method is to calculate the water vapor transmission rate of the sample according to the increase in the weight of the permeable cup. The specific implementation process is to place a desiccant in the permeable cup, seal the sample at the mouth of the 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, providing power for water vapor to penetrate from the test chamber through the sample into the permeable cup. The water vapor that penetrates into the permeable cup is absorbed by the desiccant, causing the weight of the permeable cup to change. By testing the increase in the weight of the permeable cup over time, the water vapor transmission rate of the sample is obtained.
Test sample and test process
Test sample: a certain brand of aluminized BOPP tape.
Test process:
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), and 3.4589 g/(m2·24h). The entire test process is simple to operate and the equipment is highly intelligent. From the above test results, the uniformity of the water vapor transmission rate test results of the aluminum-coated BOPP tape samples is good, indicating that the moisture resistance of each part of the sample is uniform.
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