Wuhan Handern heat shrinkable film
DATE：2021/8/4 8:29:31 / READ： / SOURCE：This station
Wuhan Handern heat shrinkable film
The material mold is stretched in a high state, and the stretch is frozen after cooling. When heated, the plastic has a tendency to restore the size before stretching. This so-called "elastic memory" is the meaning of heat shrinkable film packaging. . For heat-shrinkable films, shrinkage rate, shrinkage tension and shrinkage temperature are three important characteristic indicators, which are all related to the material of the plastic and the production process. www.handern.com heat shrinkable film equipment
For typical amorphous polymers, such as PS, the shrinkage of the biaxially stretched heat shrinkable PS film does not occur before the temperature is gradually heated to below tg, but only thermal expansion occurs. When the temperature is higher than the temperature, the shrinkage rate varies with the temperature. Increase and increase until the viscous flow begins. The shrinkage rate is related to the conditions of the film stretching. If the stretching is performed under low temperature, high stretching rate and quenching conditions, when heated, almost 100% recovery before stretching size of. www.handern.com heat shrinkable film equipment
If other conditions remain unchanged and the stretching is carried out at a higher temperature, the shrink film cannot be fully recovered when heated due to relaxation. For crystalline polymers, such as PET stretch-oriented film, after heat setting, it will not shrink after heating. To shrink it, it must be heated above the heat setting temperature to shrink, in order to reduce the crystalline polymerization The shrinkage temperature of the film is biaxially stretched at a temperature above (glass transition temperature) (see Table 3-81), and it is sold as a heat shrinkable film without heat setting. www.handern.com heat shrinkable film equipment
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