Gas Barriers: An Introduction Basic Reference 1
Wrapping refers to a means of separating something that lies "inside" from an "outside". This is done to protect the contents from outside factors such as humidity, light, pressure, and air. The wrapping (packaging material) must seal the contents from outside factors and protect them to prevent degradation in quality.
"Barrier properties" is the term used for the function of sealing contents from outside factors that will invite quality degradation. Oxygen, nitrogen, carbon dioxide, water vapor, and other gases in the air have a major impact on the freshness and quality of food products and medicines, and barrier properties for these gases are thus extremely important. For this reason, the packaging materials must have barrier properties with respect to these gases.
Figure 1-1 "Packaging Materials" seal the contents from the outside air and prevent degradation of the quality of the package contents.
For many years, bottling and canning have been used as methods to seal contents from the outside air, enabling these contents to be preserved for many years. When plastics were invented in the 20th century, they came to be used as packaging materials. Plastics with excellent gas barrier properties were developed, and supported our lifestyles as packaging materials not only for food products but cosmetics and pharmaceuticals as well.
Figure 1-2 polyethylene(left)and ethylene-vinyl alcohol copolymer(right)
Figure 1-2 shows polyethylene (PE), an ordinary plastic, and ethylene-vinyl alcohol copolymer (EVOH), a plastic with excellent gas barrier properties. A comparison of these plastics shows that they are both transparent and are almost identical in appearance. However, EVOH has more than 10,000 times the oxygen gas barrier properties of PE. Why is there such as tremendous difference in the oxygen gas barrier properties of these plastics? To answer this question, we will present a brief explanation of the mechanisms and so forth that give rise to barrier properties. Next time, we will discuss the required form of expressing gas transmission quantity when a comparison is made of the quantity of gas transmitted.
Global navigation
