Abstract: The desiccant should have the ability to adsorb water vapor in time, which requires the material used for packaging desiccant to have high moisture permeability. In this paper, the water vapor transmission rate of the packaging materials used in the desiccant is tested by the cup method principle, and the parameters, application range and test procedure of the test principle, equipment W3/062 water vapor transmission rate test system are adopted. The introduction provides a reference for how to monitor the moisture permeability of desiccant packaging.
Key words: moisture permeability, water vapor transmission rate, water vapor transmission rate tester, cup method, weighing method, weight gain method, weight loss method, desiccant, packaging material
1 , meaning
There are many types of desiccant, such as calcium chloride, phosphorus pentoxide, silica gel, molecular sieve, montmorillonite, etc., which can be used for drying instruments, electronic products, leather, shoes, clothing, food, medicine and household appliances. Store to protect the product from moisture or rust. When drying products such as foods and medicines, the desiccant should be placed in a separate package to separate it from the contents, such as filter paper, non-woven fabric, composite paper, textured paper, wax paper, DuPont paper, etc., as shown in Figure 1 . It can be seen that the desiccant is not directly in contact with the water vapor in the environment to be dried, and the water vapor needs to penetrate into the interior of the package of the desiccant to be absorbed by the desiccant. Therefore, the moisture absorption rate of the desiccant is not only related to the type and size of the desiccant, but also depends on the moisture permeability of the packaging material. The good moisture permeability contributes to the rapid absorption of water vapor by the desiccant. The moisture permeability of the packaging materials used in the desiccant was tested in a targeted manner.
Figure 1 Individually packaged desiccant
2 , test samples
In this paper, a gas permeable membrane for a desiccant package is used as a test sample to test its water vapor transmission rate.
3 , the test basis
The test methods for water vapor transmission rate of packaging materials include cup method, infrared sensor method, electrolytic sensor method and humidity sensor method. In view of the high water vapor transmission rate of the sample tested in this paper, the cup method is used for testing. .
4 , test equipment
This test uses the W3/062 water vapor transmission rate test system to test the sample. The equipment 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 principle of cup method is to obtain the water vapor transmission rate of the sample by weighing the change of the quality of the moisture permeable cup with the penetration time. According to the increase or decrease of the mass of the moisture permeable cup, the principle can be divided into weight gain method and weight loss. Two methods. The weight-increasing method refers to a certain amount of desiccant contained in the moisture-permeable cup. After the sample is clamped, the outside of the moisture-permeable cup is in a high-humidity environment, and the water vapor permeates from the outside of the moisture-permeable cup through the sample into the inside of the moisture-permeable cup. The absorption of the desiccant causes the mass of the moisture-permeable cup to increase; the weight-reduction method refers to the inside of the moisture-permeable cup containing a certain amount of distilled water. After the sample is clamped, the outside of the moisture-permeable cup controls the low-humidity environment, and the water vapor passes through the inside of the moisture-permeable cup. The sample penetrates into the outside of the moisture permeable cup, causing the quality of the moisture permeable cup to be reduced. The water vapor transmission rate of the sample can be obtained by testing the change in the permeation time of the mass of the moisture permeable cup.
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, paper-plastic composite film, geomembrane, aluminized film, aluminum-plastic composite film, waterproof and breathable film, etc., 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 fabrics, diaper non-woven fabrics, sanitary products Textiles, non-woven fabrics and other materials. 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.
4.2 Equipment parameters
Two test modes of weight gain method and weight loss method can be realized. The weight gain method test range is 0.1 ~ 2,500 g / (m 2 · 24h) , and the weight loss method test range is 0.1 ~ 10,000 g / (m 2 · 24h) . The test accuracy is 0.01 g/(m 2 ·24h) , the system resolution is 0.001 g ; 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 accuracy 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 The range is 0.5 ~ 2.5 m / s ; the sample size is Ф74 mm , the test area is 33 cm 2 ; the system automatically weighs intermittently, the system is automatically cleared before each weighing, and the test chamber can accommodate 6 moisture permeable cups. Each moisture permeable cup can be tested independently and can test six identical or different samples simultaneously, supporting the Lystem TM laboratory data sharing system.
5 , the test process
According to the actual application of the desiccant packaging film sample used in this test, the weighting method was used for the test.
(1) A sample sampler was used to cut three samples having a diameter of 74 mm from the surface of the sample.
(2) loading the sample charged in an amount of desiccant permeable cup, according to the cover of tailored heat the sample toward the inside of the moisture permeable cup way the three samples were clamped in a permeable cup 3, through The desiccant inside the wet cup should not touch the sample.
(3) Test The moisture permeable cups with the specimens placed are placed on the moisture permeable cup holder inside the test chamber of the equipment, and the test chamber door is closed. Set the sample name, test mode, test interval and other parameter information on the control software of the device. Click the test option, the device will automatically perform intermittent weighing according to the set parameters, and the test result will be displayed after the test.
6 , test results
The test values ​​of the three samples tested in this test were 2156.1 g/(m 2 ·24h) , 2204.9 g/(m 2 ·24h) , 2167.3 g/(m 2 ·24h) , and the desiccant packaging film samples. The water vapor transmission rate is an average of 2176.1 g/(m 2 ·24h) of the test results of the three samples.
7 , conclusion
Place desiccant independent packaging is a common drying method for food, medicine, clothing and other products. In order to ensure that the desiccant can absorb water vapor in time to achieve good drying effect, the packaging material should have excellent moisture permeability. In this paper, the water vapor transmission rate of the desiccant packaging film sample is tested by the weight gain method in the cup method. The test process is simple, the equipment is easy to operate, the degree of intelligence is high, the test result is accurate and reliable, and the sample can be completed quickly and effectively. Test for moisture permeability. In addition to the weight gain method, the device can also realize the water vapor transmission rate of the packaging material by using the weight reduction method, and has high cost performance. 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 existing equipment has been applied to food, pharmaceutical, packaging materials manufacturers, daily chemical products, automobiles, electronics, third parties. Testing institutions and universities and other industries and fields. The more you understand, the more you trust! Labthink is looking forward to enhancing technical communication and cooperation with enterprises and institutions in the industry.
Rapid Antigen Test,Virus Dignosis Test Kit,Covid-19 Detection Kit,Covid-19 Rapid Test Cassette
Hangzhou DIAN Biotechnology Co., Ltd. , https://www.dianbiotech.com