Factors Affecting Air Permeability

Factors Affecting Air Permeability

① The higher the degree of beating, the lower the air permeability of the paper.

② The relative humidity of the environment increases, and the air permeability of the paper decreases.

moisture permeability

Gas generally has the characteristic of diffusing from a place of high concentration to a place of low concentration, and the same is true for water vapor. A certain thickness of metal material or glass material can substantially block this diffusion. However, for packaging , although their thickness is uniform and there are no physical holes or voids, water vapor in the air can still form molecules in paper, cardboard, plastic films, etc. Penetrates and can diffuse in packaging materials. Therefore, packaging materials such as paper, cardboard, and plastic film have moisture permeability. The moisture permeability of paper and cardboard will directly affect the quality and shelf life of the contents, especially for the preservation of dry food, as the moisture content increases due to moisture absorption, the quality of the contents will decrease. For example, tea should be packaged in moisture-proof packaging, and if the moisture exceeds 5.5%, the quality of the tea will drop sharply. Usually, performance tests such as moisture resistance, moisture resistance or oil resistance are used to evaluate the permeability of paper against water vapor and liquid.

test instrument

The test instruments for paper and cardboard moisture permeability include temperature and humidity control box, drying box, moisture permeability cup, moisture permeability rapid test machine, electric

moisture permeability cup, pneumatic vapor vapor permeability Tester, pocket electronic humidity measuring instrument, Schopper water permeability meter,

Water resistance Tester and oil permeability Tester, and temperature and humidity control box, drying box, moisture permeable cup, moisture permeable rapid test machine,

Electricity measurement moisture permeability cup and pneumatic vapor permeability Tester are also suitable for determining the moisture permeability of plastic films.

Since the moisture permeability of paper and cardboard is worse than that of plastic film, it is rare to use paper or cardboard alone in moisture-proof packaging.

In most cases, composite plastic films, including paper/plastic composite films, are used.