Abstract: Aluminized films play a decisive role in the field of soft plastic packaging materials and are a kind of packaging material with high barrier properties. In this paper, the Labthink blue light W3/330 water vapour permeability test system was used to test the change of the moisture resistance data of the aluminized film samples with the aluminum-plated surface facing the high-humidity side and the non-aluminized surface facing the high-humidity side. In the design of packaging materials structure and testing soft plastic packaging moisture resistance and other aspects to provide reference.
Keywords: aluminum-plated film, aluminized surface, non-aluminized surface, moisture barrier, water vapor transmission rate, water vapor transmission rate test system
1 , the meaning
Aluminum-plated film is a kind of soft plastic packaging material formed by applying a special process such as vacuum aluminum plating on the surface of the plastic film to coat a very thin layer of alumina. Common aluminized films include PET aluminum film ( VMPET ), CPP aluminum film ( VMCPP ), and BOPP aluminized film ( VMBOPP ). These aluminized films can be used as packaging materials alone or in combination with other film materials. Aluminized composite film serves as the outer packaging of the product. For the aluminum-plated film, due to the presence of the aluminum-plated layer, the gas barrier, moisture-blocking, light-blocking, and fragrance-preserving properties of the film are greatly improved. At the same time, the material has a metallic luster and a bright appearance. A good beautify the packaged product, and the cost of the package is cheaper. In view of these advantages of aluminized films, more and more products have been used as packaging materials, such as coffee, milk powder, potato chips, mustard, grains or Powder medicines, tea, candy, etc.
Figure 1 aluminum film
The barrier properties of aluminized films are related to the degree of compaction of the aluminized layer, the thickness of the aluminized layer, and the aluminizing process. Some aluminum-plated films will have a reduced barrier property when exposed to high humidity. This is probably because a high-humidity environment can destroy the structure of the aluminum plating layer and cause irreversible damage to the aluminum plating layer, which in turn severely affects the overall barrier of the film. performance.
2 , reference standards
At present, domestic testing methods for water vapor transmission rate of soft plastic packaging include weighing method ( cup method ) , electrolysis method, humidity method, and infrared sensor. Reference standards are GB 1037-1988 . Test method for steam permeability of sheets - Cup method, GB/T 16928-1997 "Test methods for moisture permeability of packaging materials ", GB/T 21529-2008 "Determination of water vapor transmission rate of plastic films and sheets - Electrolytic sensors Method, GB/T 30412-2013 "Determination of moisture vapor transmission rate of plastic films and sheets ", GB/T 26253-2010 " Infrared detector method for determination of water vapor transmission rate of plastic films and sheets ". The standard referenced herein is GB/T 21529-2008 , the electrolytic sensor method.
3 , test sample
Aluminum coating produced by a packaging plant.
4 , test equipment
In this paper, the W3/330 water vapor transmission rate test system independently researched and developed by Jinan Languang Electromechanical Technology Co., Ltd. was used to test the corresponding water vapor transmission rate of the test surface facing the high humidity side.
Figure 2 W3/330 Water Vapor Transmission Rate Test System
4.1 Equipment Principle
This device is developed using electrolytic sensor method test principle. During the test, nitrogen with stable relative humidity flows on one side of the membrane and dry nitrogen flows on the other side of the membrane. Due to the presence of a moisture gradient, water vapor diffuses from the high-humidity side through the specimen to the low-humidity side, at low humidity. On the other hand, the transmitted water vapor is carried by the flowing dry nitrogen gas to the sensor to generate the same proportion of electrical signals. Through the analysis and calculation of the sensor electrical signals, the water vapor transmission rate and other parameters of the sample are obtained. If the test sample is a packaging container, dry nitrogen flows in the container and the outside of the container is in a highly humid state.
4.2 Scope of application
(1) This equipment is applicable to the testing of the water vapor transmission rate of packages such as films, sheets, paper, paperboard, composite materials and containers. The films include various plastic films, plastic composite films, paper-plastic composite films, co-extruded films, aluminized films, aluminum foils, aluminum foil composite films, glass fiber aluminum foil composite films, etc.; sheet materials including various engineering plastics, rubbers , sheet materials such as building materials, such as PP sheet, PVC sheet, PVDC sheet, etc.; paper, cardboard and composite materials including paper, cardboard, etc., such as cigarette pack aluminum paper, paper aluminum plastic composite sheet, etc.; Containers include water vapor transmission rate tests for bottles, bags, cans, boxes, and barrels made of plastics, rubber, paper, paper-plastic composites, glass, and metal, such as Coke bottles, peanut oil drums, Tetra Pak packaging, and vacuum. Packaging bags, metal packaging bags, metal three-piece cans, plastic cosmetic hose packaging, toothpaste hose packaging, jelly cups, etc.
In addition, through special configurations, the device can also be used for the testing of water vapour permeability of special packages such as pharmaceutical blisters, pharmaceutical plastic bottles, instant noodle bowls, paper cups, paper bowls, automobile fuel tanks, and battery plastic housings.
(2) This equipment complies with many national and international standards such as GB/T 21529 , ISO 15106-3 , DIN 53122-2 , YBB00092003, etc.
4.3 Equipment Parameters
The test range of film samples is from 0.001 to 40 g/(m2·24h) with a resolution of 0.001 g/(m2·24h) . The test range of containers is from 0.0001 to 0.2 g/(pkg·24h) . The rate is 0.00001 g/(pkg·24h) . The test temperature range is 15 °C ~ 55 °C , temperature control accuracy is ± 0.1 °C ; humidity range is 0%RH , 35%RH ~ 90%RH , 100%RH , humidity control accuracy ± 1% RH . The device is equipped with three test chambers. The three test chambers can be designed independently. The test process does not interfere with each other and the test results are displayed independently. The system can support up to 10 instruments in parallel and establish an efficient system with 30 samples simultaneously tested. A standard membrane is provided for system calibration to ensure the accuracy and versatility of the test data. It can be used together with the oxygen permeability test system to form a hybrid test system, which is controlled by a computer to achieve an efficient and convenient test method for the simultaneous measurement of water vapor and oxygen transmission rates. LystemTM laboratory data sharing system is supported to uniformly manage test results and test reports.5 , the test process
(1) Cut 6 specimens from the surface of the aluminized film sample using a cutter .
Figure 3 cut aluminized sample
(2) Take any 3 samples of them, and the aluminized layer faces the high-humidity side, and mount them on the 3 test chambers of the equipment .
(3) Set the sample thickness, test temperature, test humidity and other parameters.
(4) Adjust the pressure of nitrogen gas so that the humidity in the test chamber reaches the set value, and adjust the nitrogen gas flow rate knob so that the nitrogen flow in the upper and lower chambers reaches the standard value.
(5) Click on the " Start Test " option and the test begins. The instrument automatically calculates and displays the test results.
(6) The non-aluminized surface of the remaining three specimens is oriented toward the high-humidity side and clamped in the equipment. Repeat steps (3) through (5) to test the water vapor transmission rate.
6 , test results
When the aluminum surface facing the high humidity side, the water vapor permeability three samples were 1.431 g / (m2 · 24h) , 1.395 g / (m2 · 24h), 1.517 g / (m2 · 24h), 3 sheet The water vapor transmission rates of non-aluminized surfaces toward the high-humidity samples were 0.667 g/(m2·24h) , 0.654 g/(m2·24h) , and 0.670 g/(m2·24h), respectively .
7. Conclusion
Some water vapor transmission rates measured on the high-humidity side of some aluminized products have a gap, and this phenomenon is mainly related to the adverse effect of the high-humidity environment on the aluminum layer with poor compactness. Therefore, according to the characteristics of the packaged products and the humidity of the circulation environment, etc., the detection of the moisture resistance of the aluminum-plated films should be strengthened, and sufficient attention should be given to the design of the package structure and the selection of packaging materials. The W3/330 water vapor transmission rate test system is a professional test equipment for testing the moisture resistance of the sample. The device is simple to operate, with high test accuracy and good repeatability. Labthink provides you with high-end, accurate packaging testing equipment, while also improving your intimate and efficient packaging testing services. The testing equipment and services involved cover the barrier properties, flexibility and impact resistance of packaging materials. , Anti-puncture performance, heat sealing performance, sealing performance, solvent residue, evaporation residue, etc., to understand the relevant equipment information and service content, you can visit the website of Jinan Languang company to view or call directly for consultation. The more you understand, the more trust! Jinan Languang Electromechanical Technology Co., Ltd. is willing to take this opportunity to increase technical exchanges and cooperation with enterprises and institutions in the industry.
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