Nine properties of plastic film

1. Appearance

The surface of the plastic film shall be flat and smooth, free of wrinkles or only a small amount of live wrinkles, obvious unevenness, black spots, impurities, and crystal spots, no stripes, spots and other defects, no bubbles, pinholes, cracks, and no obvious bright stripes, yin and yang surfaces. In addition, the film surface shall be clean and free of dust, oil, etc.

2. Transparency and Glossiness

For transparent plastic film, the light transmittance is required to be higher, which should generally be more than 92%. For opaque plastic films, such as white films, high whiteness and good opacity are required. In addition, the plastic film should also have good glossiness.

3. Physical and mechanical properties

The physical and mechanical properties of plastic film mainly include tensile strength, elongation at break, tear strength, impact strength, etc

4. Specification and deviation

The thickness shall be uniform, the thickness deviation in the horizontal and vertical directions shall be small, and the deviation distribution shall be relatively uniform.

5. Chemical stability

In the process of printing and compounding, the plastic film must contact with ink, adhesive and some organic solvents, which are all chemical substances. Therefore, the plastic film must have a certain resistance to these chemical substances so as not to be affected by them.

6. Geometric stability

The plastic film must have a certain geometric dimension stability, otherwise, its expansion rate is too large, and it is easy to produce expansion deformation under the action of mechanical force or heat in the printing and laminating process, which will not only affect the overprint accuracy, but also cause wrinkles, curls and other problems, seriously affecting product quality and production efficiency.

7. Moisture permeability

Moisture permeability refers to the permeability of plastic film materials to water vapor under certain conditions. It represents the moisture resistance of film materials to a certain extent. The moisture permeability of various film materials is different, which also determines its application scope.

8. Oxygen permeability

It indicates the oxygen permeability of plastic film materials under certain conditions. The oxygen permeability of various film materials is different.

9. Surface tension

For example, the surface tension of biaxially oriented polypropylene film and low-density polyethylene film shall reach 3.8 × Above 10-2N/m, the surface tension of nylon film, polyester film and polyester aluminized film also has corresponding indicators.