Some standard content:
GB/T 16928—1997
This standard is equivalent to the 3030th regulation "Test for Water Vapor Permeability of Packaging Materials" in FED-STD-101. The purpose is to synchronize the test method standard of packaging materials with foreign advanced standards as much as possible, so as to adapt to the needs of international trade, technical and economic exchanges and the adoption of foreign advanced standards as soon as possible.
"FED" is the specification or standard of the United States federal government. The content of FED-STD-101 "Test Procedure for Packaging Equipment" is divided into six parts, with a total of 171 specifications, which has long been used for performance testing of packaging materials by the United States federal government, military and major industrial countries in the world. This standard adopts the 3030th regulation, of which method A and method B have long been adopted by reference in my country's national standards and industry standards, which are in line with national conditions, feasible methods and reliable results. This standard was proposed by China Packaging Industry Corporation. This standard is under the jurisdiction of the National Technical Committee for Packaging Standardization. The drafting units of this standard: The 621st Institute of China Aviation Industry Corporation and the National Packaging Product Quality Supervision and Inspection Center (Jinan) jointly wrote the chapter.
The main drafters of this standard are Luo Xiangji and Zhou Jiayan. 267
National Standard of the People's Republic of China
Test method for vapor transmission rate of packaging materials
Moisture permeability
Test method for vapor transmission rate of packaging materials1Scope
This standard specifies the test method for determining the moisture permeability of packaging materials. This standard is applicable to the moisture permeability test of paper, plastic and composite packaging materials. 2Referenced standards
GB/T16928—1997
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. IS () 2528: 1974 Determination of moisture permeability of film materials HG10-2744.2-1984 Anhydrous calcium chloride
Note: ISO2528: 1974 can be found in the translation of China Standard Information. 3 Definitions and principles
3.1 Definitions
Moisture permeability
refers to the mass of water vapor that passes through a unit area of the test material within a specified time when the test material is kept at a constant temperature and one side is exposed to high relative humidity conditions, expressed in g/(m2·24h). 3.2 Test principle
Under the specified temperature and relative humidity conditions, a certain water vapor pressure difference is maintained on both sides of the packaging material sample, and the amount of water vapor that passes through the sample is measured, and the mass of water vapor that passes through the test material per square meter under standard atmospheric pressure for 24 hours is measured. 4 Test instruments and reagents
4.1 Constant temperature and humidity chamber: temperature accuracy ±0.5℃; relative humidity accuracy ±2%; wind speed (0.5~~2.5)m/s. The specified temperature and relative humidity conditions should be reached within 15 minutes after the door is closed. 4.2 Analytical balance: accurate to 0.5mg. 4.3 Desiccant: anhydrous calcium chloride with a particle size of 0.60mm~～2.36mm, which must be new, unused, and in accordance with HG10-2744.2 standard.
4.4 Special equipment for method A: in accordance with ISO2528 standard. 4.5 Special equipment and instruments for method B 4.5.1 Heat sealing equipment: capable of controlling temperature, pressure and holding time. 4.5.2 Materials for desiccant: high moisture permeability and heat-sealable, such as tea bags or paper bags or non-woven fabrics for desiccant (hereinafter referred to as bag-making materials).
Approved by the State Administration of Technical Supervision on July 29, 1997 268
Implemented on January 1, 1998
5 Samples
GB/T 16928 -- 1997
5.1 Unless otherwise specified, samples shall be randomly selected and sufficient in number to represent the performance of the product. 5.1.1 Method A Each sample shall be a piece of the tested packaging material, and the size shall meet the requirements of the equipment use in Article 4.4. The number of samples for each test environment shall not be less than 3. If the materials on both sides of the sample are different, the number of samples shall not be less than 6. The sample shall comply with the provisions of ISO2528.
5.1.2 Method B Each sample shall be a piece of the tested material of 200mm×300mm, and the number of samples for each environment shall not be less than 4, with 2 samples taken along the longitudinal and transverse directions of the material.
6 Test conditions
Unless otherwise specified, the test conditions shall be selected according to the actual use requirements of the packaging material, and one or more of the following conditions shall be selected: a) Temperature (38±1)℃, relative humidity (92±3)%; b) Temperature (23±1)℃, relative humidity (49±3)%; c) Temperature (4.5±1)℃, relative humidity (80±3)%; d) Temperature (-18±1)℃, relative humidity (95±3)%; During the arbitration test, the temperature deviation is ±0.5℃; the relative humidity deviation is ±2%. 7 Test procedures
7.1 Method A is to seal the test material in the mouth of the test cup filled with desiccant. It is applicable to general packaging materials, including heat-sealable materials and sealing tapes. It is not recommended to use this method for materials with a moisture permeability of less than 1g/(m2·d) or a thickness of more than 3mm. 7.2 Method B is to make the test material into a bag, which is mainly used for the test of heat-sealable materials that can be made into bags and have low moisture permeability. 7.3 Methods A and B can be used for the development, production and inspection of packaging materials. They are also suitable for testing packaging materials after folding, aging or other environmental treatments.
7.4 Method A
7.4.1 Place the desiccant evenly in the permeable cup, and the gap between the desiccant and the sample should not be less than 3mm. Seal the sample at the mouth of the permeable cup so that water vapor cannot penetrate at or through the edge of the sample. The specific operation steps shall be carried out in accordance with ISOO2528. 7.4.2 Place the permeable cup with the sample sealed (hereinafter referred to as the permeable cup) on the analytical balance and weigh it. Then put it into a constant temperature and humidity chamber so that the sample can freely contact the test environment.
7.4.3 According to the moisture permeability of the material, select a suitable time interval to weigh the permeable cup continuously, and make a graph of the weight change and time relationship. The weighing should preferably be carried out in the test environment, otherwise the weighing time should not exceed 30S. During the weighing operation, if the weight of the permeable cup cannot be kept constant, it should be placed in a container that can keep the test environment non-hygroscopic for weighing. If this condition cannot be achieved, the permeable cup can be taken out of the constant temperature and humidity chamber and placed in a desiccator at (23 ± 2) °C for 30 minutes before weighing. Continue the test until a stable weight gain is achieved, that is, three consecutive data are located on a straight line when the graph is drawn. 7.5 Method B
7.5.1 Sample preparation
Fold the sample into 150 mm × 200 mm, and seal the two short sides and one long side with heat sealing conditions that meet the sample. The sealing width is (65 ± 0.5) mm, ensuring that the internal width of the sample should be (135 ± 2) mm. 7.5.2 Preparation of desiccant bags
Cut a bag-making material with a length of 270 mm and a width of 90 mm that meets the requirements of 4.5.2, fold it in half to a length of 135 mm and a width of 90 mm, heat-seal the two long sides, and the sealing width shall not exceed 6 mm to make a desiccant bag. Each group of samples shall have no less than 3 bags. 7.5.3 Fill each desiccant bag with at least 50 g of desiccant, and then seal the third side. 7.5.4 Put the sealed desiccant bag into the sample bag, and seal the bag mouth so that the inner side of the seal is no more than 9.0 mm from the outer edge of the bag. 7.5.5 Place the sample in the exposure environment. The equilibrium time is shown in Table 1. 269
GB/T16928--1997
7.5.6 Unless otherwise specified, after the equilibrium time specified in Table 1, take the bag out of the constant temperature and humidity chamber, immediately cut off a 10mm narrow strip at one end of the short side of the sample, open the sample bag, take out the desiccant bag 1 from the bag, replace it with the weighed bag 1 filled with new desiccant, reseal the bag according to 7.2.4 and immediately put it into the constant temperature and humidity chamber, and record the time of putting it in, which is the start time of the test. Unless otherwise specified, when the exposure time specified in Table 1 is reached, the desiccant bag 1 should be taken out of the sample bag immediately and placed in a moisture-proof container of known weight for weighing. You can first use a flat, hole-free, wrinkle-free polyethylene film with a thickness of 0.05 to 0.10 mm to make a size larger than the desiccant bag, pre-weigh it to an accuracy of 0.5 mg, and put it in a desiccator for use. Table 1
Test methodsbzxz.net
Method A
Method B
Test conditions
Temperature, ℃
-18±1
Relative humidity,%
1) 24h is used for thin single-layer packaging materials; longer time is used for multi-layer composite materials. Sample bag equilibrium time
24721)
24~721
240~336
Time interval between two weighings\
2) If the linear relationship of the test results cannot be obtained within this test time, the sample should be checked for air leakage. If air leakage is found, the test should be repeated. If there is no air leakage, a new sample should be used and the test time should be shortened and repeated. 3) The time interval between two weighings can be 8h or longer. 7.5.7 Record the date and time of the start and end of the test, the weight and time of each weighing. After the test, flatten the sample bag, measure and record the internal length and width of the sample bag along the center line. 8 Calculation of test results
8.1 The moisture permeability of the sample is calculated according to formula (1).
WVTR = Aw × 24/(A × t)
Wherein: WVTR——water vapor transmission rate, g/(m2.24 h); Au
weight gain or weight loss, g;
A——exposed area of the specimen (area within the edge of the seal), m; time interval between two weighings after the weight gain or weight loss is stable, h. 9 Test report
The test report shall at least include the following: a) the number of this standard;
b) detailed description of the test specimen and test piece; c) method A or B,
d) environmental conditions during the test;
e) specimen thickness and area through which water vapor can pass, f) test parameters;
g) test results;
h) differences from this standard during the test; i) test date, signature of the test personnel, and seal of the test unit. 270
. (1)
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