The first to understand how fogging film happens in packaging process is the way to figure out how to prevent film from fogging. In case of general transparent packaging materials, fogging comes from object of its kind being in high and low temperature. In the packaging product, water vapor, after being hot or cold, turns into droplets condensed onto surface of object. The fog is seen as white caused by incident light reflection.

There are few anti-fog treatments based on the principles as follows.

A) Surface Hydrophobic Principle

Keep plastic film dry by forming water vapor resistant structure.

B) Surface Hydrophilic Principle

When Surface Hydrophobic Principle is to prevent film from water vapor, Surface Hydrophilic Principle is tried to make film moisturize and vapor contact angle is getting less.

C) Inner Activate Agent Added Principal

The activated film is made out by adding surfactant into formulation, which the active agent gradually spreads out to surface from inside and structures are reorganized. Thereby, the hydrophilic group comes out to surface and make film hydrophilic.

D) Whole Activation on Plastic Principal

The product produced by adding small amount of crystal salt-base additive into plastic formulation system loses crystal water due to high temperature during the day and absorbs water at night in low temperature.

E) Plastic Surface Temperature Difference Principal

Prevent film from fogging by keeping film surface temperature higher than dew point.

Anti-Fog Film Process Production

Production of Anti-Fog Film basis with the mentioned principles are processed mainly into two ways: Internal-Added production and External-Coated Production.

A) Internal-Added Production

This production can complete by either directly adding anti-fog agents or adding masterbatch. The internal addition is mostly used in anti-fog film due to simple and convenient production with lower cost.

B) External-Coated Production

This production is excellent in wettability and good in effect. Due to poor adhesion in the middle of anti-fog agent and plastic film, other concerns such as higher cost and poor anti-fog coating durability, the application of anti-fog coating film is limited.

Application of Anti-Fog Film

When the chilled food packed without anti-fog film, the consumers have difficulty to see how appeal of food it is neither nor whether or not the fruits and vegetables are fresh. This will lower their willingness to purchase. Therefore, an excellent anti-fog effect packaging film can improve food packaging presence, preserve food freshness and induce consumers to purchase.