Is There Any Difference Between One-Way Stretch and Two-Way Stretch of Protective Film?

As a PE Protective Film Manufacturer, share with you.

Many people can't distinguish between unidirectional stretching and bidirectional stretching of protective film. Many people mistakenly think that unidirectional stretching starts from one side, while bidirectional stretching starts from two sides. In fact, this is not the case.

PE Self-Adhesive Protective Film

The stretching method is to stretch the heated plastic film longitudinally and laterally to change the molecular order, thereby changing the properties of the film, that is, stretching in one direction (horizontal) means unidirectional stretching, along two directions (horizontal and longitudinal) Stretching is bidirectional stretching, for example, stretching in the east-west direction is unidirectional stretching; stretching in the east-west direction is stretching in the north-south direction, which is called bidirectional stretching.

Obviously, bidirectional stretching can be divided into transverse stretching and longitudinal stretching, and unidirectional stretching is only one of the directions.

Plastic films used for biaxial stretching mainly include polyester film, polypropylene film, polyamide film, polystyrene film and polyimide film.

Especially for optical films using precise stretching technology, such as retardation films, it can not only increase the viewing angle, but also improve the polarizing film, which is very important for products such as LCD displays.

In addition, stretching technology is also used in the production process of lithium battery separators, and the dry stretching process can be divided into a uniaxial stretching process and a biaxial stretching process. The dry drawing method is used to produce hard elastic fibers, and a highly oriented polypropylene or polyethylene film with low crystallinity can be prepared, and an oriented film with high crystallinity can be obtained after high temperature annealing. The film is first stretched at low temperature to form micro-defects, and then at high temperature, the defects are elongated to form micro-pores.

The elongation method can also be used to produce porous membranes, such as membranes that can separate foreign matter in a filter and have permeability.

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