Source：Linktesting Instruments Co.,Ltd.
Diapers are commonly used daily necessities for babies. Dry diapers can keep babies sleeping all night. Because of their strong water absorption, they are commonly called "diapers." Diapers are generally divided into three main components, the surface covering layer, the absorbent core layer and the base fabric. According to the different functions of the three components, the materials used are also different: the surface coating layer is used to promote the rapid penetration of urine and effectively prevent back seepage, and most of them are made of non-woven fabric; the absorbent core layer is the key component of the diaper. Mainly composed of pure wood pulp and super absorbent resin, its function is to quickly absorb urine, disperse urine or diffuse urine into the entire core layer through capillary action, and finally absorb and store urine; the bottom cloth is the most important thing in diapers. The main function of the outer layer is to breathe and prevent leakage. Domestically, polyethylene PE film is mainly used, while non-woven fabrics have been used abroad.
This article introduces the moisture permeability test of diapers to explain the importance of moisture permeability to diapers. If the moisture permeability of the outer PE film of the diaper is poor, it will easily cause the diaper to leak, and it will not be possible to ensure that the baby's buttocks are dry, which will cause the baby to appear red. Buttock, eczema and other problems. Therefore, diaper manufacturers should strengthen regular monitoring of the moisture permeability of the outer PE film of the diaper.
Test method and instrument
At present, the Chinese testing methods for water vapor transmission rate of flexible plastic packaging include weighing method (cup method), electrolysis method, humidity method and infrared method. Test Method for Water Vapor Permeability of Sheets: Cup Method, GB/T21529-2008 "Determination of Water Vapor Transmission Rate of Plastic Films and Sheets-Electrolytic Sensor Method", GB/T30412-2013 "Water Vapor Transmission of Plastic Films and Sheets" Determination of the rate of humidity sensor method", GB/T 26253-2010 "Plastic film and sheet water vapor transmission rate of infrared detector method". The standard referred to in this article is GB 1037-1988 "Plastic Film and Sheet Water Vapor Permeability Test Method Cup Method".
The testing equipment used in this test is Linktesting LTWPT-304 water vapor transmission rate tester
Test principle: This equipment is developed using the weighing method test principle. During the test, the sample is clamped in a moisture-permeable cup. A certain humidity difference is formed on both sides of the sample. Water vapor will penetrate through the sample from the high-humidity side to the low-humidity side under the action of the humidity difference. The weight of the wet cup is measured over time, and the water vapor transmission rate and other parameters of the sample can be obtained.
Test sample and test process
Test sample: diapers provided by a certain company.
(1) Cut 3 specimens with a diameter of 74 mm from the surface of the sample.
(2) Clamp the samples in the 3 moisture-permeable cups respectively, and then put them on the moisture-permeable cup holders inside the equipment, and close the test chamber door.
(3) Set the test temperature, humidity, sample thickness and other parameter information in the special software system of the equipment configuration, and click the test option to start the test.
(4) The equipment automatically calculates the water vapor transmission rate of the sample based on the monitoring result.
Test results and analysis
The water vapor transmission rates of the three samples of the outer PE film of the diaper tested in this test are: 1218.26 g/m2·24h, 1320.11 g/m2·24h, 1286.73 g/m2·24h. The LTWPT-304 water vapor transmission rate tester is a professional instrument for testing the water vapor transmission rate of thin films. The equipment is easy to operate, has high test accuracy and good repeatability. It can accurately reflect the resistance of the outer PE film of diapers. Wetness.
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