Nine properties of plastic film

1, appearance

The surface of the plastic film should be smooth and smooth, wrinkle-free or only a small amount of active pleats, no obvious unevenness, black spots, impurities, and crystal points, no streaks, spots and other defects, no bubbles, pinholes and cracks, no Allow obvious bright bars, yin and yang faces and so on. In addition, the surface of the film is required to be clean and free from dust and oil.

2, transparency and gloss

For transparent plastic film, its light transmittance is higher, generally should be above 92%. For opaque plastic films, such as white film, it is required to have high whiteness and good opacity. In addition, the plastic film should also have good gloss.

3, physical and mechanical properties

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

4, specifications and deviations

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

5, chemical stability

Plastic films are exposed to inks, adhesives, and certain organic solvents during printing and lamination. These are chemicals. Therefore, plastic films must have some resistance to the chemicals they are exposed to, so that they are not affected by them. influences.

6, geometric dimensional stability

Plastic film must have certain geometric dimensional stability. Otherwise, its expansion ratio is too large. It is easy to produce telescopic deformation due to mechanical force or heat during printing and compounding process, which not only affects the overprinting accuracy, but also wrinkles. Problems such as curling seriously affect product quality and production efficiency.

7, moisture permeability

The moisture permeability indicates the amount of water vapor permeation of the plastic film material under certain conditions. It represents the moisture resistance of the film material to a certain extent, and the moisture permeability of various film materials is different, which also determines its application. range.

8, oxygen permeability

It indicates the amount of oxygen permeation of the plastic film material under certain conditions, and the oxygen permeability of various film materials is also different.

9, surface tension

For example, the surface tension of the biaxially oriented polypropylene film and the low density polyethylene film is required to be 3.8×10-2 N/m or more, and the surface tension of the nylon film, the polyester film, and the polyester aluminized film also has corresponding indexes. In general, plastic films must be surface treated to improve surface tension before printing or compounding, and can be smoothly printed and composited.

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