Abstract : Water vapor transmission performance is one of the important properties affecting the use of latex paint. This paper introduces a test method for the moisture permeability of such a product by testing the water vapor transmission rate of a brand of latex paint. The test principle and the applicable scope and parameters of the test equipment W3/062 water vapor transmission rate test system are introduced to provide reference for monitoring the water vapor transmission performance of latex paint and related products. Keywords : latex paint, water vapor transmission performance, water vapor transmission rate, moisture permeability, moisture resistance, water vapor transmission rate test system, coatings, building materials 1 , meaning Latex paint is an organic paint commonly used in the construction industry, also known as synthetic resin emulsion paint. It is classified according to the production raw materials, the use environment and the decorative gloss effect, such as polyvinyl acetate latex paint, ethylene-propylene latex paint, pure acrylic acid. Latex paint, interior latex paint , exterior latex paint , matt latex paint, matt latex paint, semi-gloss emulsion paint, mercerized latex paint, etc., no matter what kind of latex paint, in addition to its good protection and decoration effect It should also have excellent water vapor transmission properties. After the latex paint is applied, the wall usually contains a certain amount of water, and in the rain or snow weather or indoor humidity, the water will inevitably enter the wall and the paint film through the paint film, if the latex paint The moisture permeability is poor, and the water vapor in the wall and the paint film cannot be lost through the paint film in time, which will cause a certain pressure on the paint film, causing the foaming phenomenon of the paint film to be formed, or even falling off, affecting the construction. Therefore, the research and detection of the water vapor transmission performance of latex paint is one of the important ways to improve the quality of products and construction. Figure 1 latex paint 2 , test samples In this test, a sheet material made of a brand of latex paint was used as a test sample. 3 , testing basis At present, the test methods for water vapor transmission rate of materials mainly include cup method, electrolysis method, infrared method and humidity method. Among them, the cup method is divided into two methods: weight gain method and weight loss method. Water vapor transmission rate test paper sample based GB / T 17146 desiccant method (i.e., the weight increase). 4 , test equipment The equipment used in this test is the W3/062 water vapor transmission rate test system, which is independently developed and produced by Jinan Languang Electromechanical Technology Co., Ltd. Figure 2 W3/062 Water Vapor Transmission Rate Test System 4.1 Test principle The desiccant is placed in the moisture permeable cup, the sample is sealed at the mouth of the moisture permeable cup, and the humidity in the test chamber of the device is controlled, so that a certain humidity difference is formed on both sides of the sample, so that the water vapor penetrates from the test chamber through the sample. Power is provided in the moisture permeable cup. The water vapor permeating into the moisture permeable cup is absorbed by the desiccant, thereby causing a change in the weight of the moisture permeable cup, and the water vapor transmission rate of the sample is obtained by testing the increase in the weight of the moisture permeable cup over time. 4.2 Scope of application (1) This equipment is suitable for water vapor transmission rate testing of various types of materials, such as plastic film, plastic composite film, paper-plastic composite film, geomembrane, aluminized film, aluminum-plastic composite film, waterproof and breathable film and other film materials. , PP sheet, PVC sheet, PVDC sheet and other engineering plastics, rubber, building materials and other sheet materials, cigarette paper aluminum foil paper, Tetra Pak and other paper, cardboard materials, waterproof and breathable fabric, diaper non-woven fabric, Textiles such as non-woven fabrics for sanitary products, non-woven fabrics, etc. In addition, it can be extended to the moisture permeability, water resistance and moisture retention test of artificial skin, medical supplies and accessories, solar back panels, liquid crystal display films, paint films, cosmetics, biodegradable films and other materials and products. (2) This equipment meets many national and international standards, such as GB 1037 , GB/T 16928 , ASTM E96 , ASTM D1653 , TAPPI T464 , ISO 2528 , DIN 53122-1 , JIS Z0208 , YBB 00092003, etc. 4.3 Equipment parameters The equipment can realize two test modes: weight gain method and weight loss method. The weight gain method test range is 0.1~2500g/(m 2 · 24h) , and the weight loss method test range is 0.1~10000g/(m 2 · 24h) . The test accuracy is 0.01g/(m 2 · 24h) , the system resolution is 0.001g , the temperature and humidity are automatically controlled, the range is wide, the precision is high, the temperature control range is 15~55 °C , the temperature control precision is ± 0.1 °C , weight loss The controlled humidity range is 70~90%RH , the weight gain method has a humidity control range of 10~98% RH , and the humidity control precision is ± 1%RH , which can test the water vapor transmission rate under different temperature and humidity conditions; the purge wind speed in the range of 0.5 ~ 2.5m / s; sample size is Ф 74mm, the test area of 33cm2; automatic intermittent weighing system, before each weighing system auto clear, test chamber can accommodate six permeable cup, each The moisture permeable cup can be tested independently and can test 6 identical or different samples at the same time , supporting the Lystem TM laboratory data sharing system. 5 , the test process (1) Three pieces of a sample having a diameter of 74 mm were cut out from a sheet material made of a latex paint sample using a cutter . (2) A certain amount of dried anhydrous calcium chloride is added to the moisture permeable cup as a desiccant. (3) The three samples taken were sealed on three moisture permeable cups which had a desiccant. (4) Place the moisture permeable cup of the sealed sample on the tray in the test chamber of the equipment, close the test chamber door, set the parameter information such as sample thickness, test temperature and humidity, and click the test option to start the test. The device automatically weighs the moisture permeable cup intermittently according to the setting parameters. (5) After the test, the device changes over time according to the weight of the moisture permeable cup 3, and displays the calculated water vapor transmission rate of three samples. 6 , test results 3 samples at 23 ℃, water vapor permeability and external moisture permeable cup relative humidity of 50% RH testing conditions were 110.621g / (m 2 · 24h) , 108.037 g / (m 2 · 24h), 113.167g / (m 2 · 24h) , that is, the water vapor transmission rate of the tested latex paint sample was 110.608 g / (m 2 · 24h) . 7 , conclusion Good moisture permeability is one of the important properties of latex paint. W3/062 water vapor transmission rate test system has simple operation, high degree of automation, stable and reliable test results in testing water vapor transmission rate of latex paint. It has good repeatability and high test efficiency, and can be used to accurately and quickly characterize the moisture permeability of latex paint. Jinan Languang Electromechanical Technology Co., Ltd. is a high-tech enterprise specializing in R&D, production and packaging testing services for packaging testing equipment. The packaging testing equipment and services already covered have covered the oxygen transmission rate and water vapor transmission rate of materials. , nitrogen permeability, carbon dioxide permeability and other gas barrier properties, tensile properties, friction coefficient, sealing properties, puncture resistance, impact resistance, tear strength, heat seal strength and other physical and mechanical properties, solvent residues , hygienic properties such as evaporation residue. The more you understand, the more you trust! Labthink is looking forward to enhancing technical communication and communication with enterprises and institutions in the industry! Organic pumpkin seed protein powder is made from organic pumpkin seeds through a concentrated process. 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