Meaning
The rate at which water vapor passes through a flat sheet or barrier film under specified conditions of temperature and humidity determines the moisture barrier performance of packaging. This metric, known as water vapor transmission rate, is measured in grams per square meter per day. A low value indicates that the material is highly effective at keeping moisture in or out of the package.
This measurement is essential for selecting the right packaging for dry foods and electronics.
Shelf Life
Preventing moisture gain or loss is directly related to maintaining the freshness of packaged products. For crisp foods, a high water vapor transmission rate will result in the product becoming soggy and unpalatable. For moist products, it can lead to drying out and loss of weight.
Choosing a material with the correct transmission rate prevents these quality failures.
Contractual Compliance
Technical specifications in distribution agreements often require packaging to meet specific barrier performance limits. A retailer may reject shipments of goods if the water vapor transmission rate of the packaging fails to meet the standards set in the quality agreement. This failure can lead to returned orders and financial penalties for the manufacturer.
Ensuring that packaging materials consistently meet these technical specifications is necessary for maintaining long-term supply contracts.
Material Optimization
Selecting the correct polymer blend or coating is necessary to achieve the desired barrier performance at the lowest cost. Manufacturers can lower the water vapor transmission rate of their packaging by using thicker materials or adding coextruded layers like PVDC or metallized coatings. However, these additions increase the cost and weight of the packaging, which can impact transportation costs.
Engineers must carefully balance the barrier performance of the material against the budget and environmental targets of the project to find the most efficient solution. Testing various film combinations under simulated transport conditions allows companies to optimize the packaging design before full-scale distribution.
