Influence Of Molding Process On The Properties Of Breathable Film Backsheet

Polyolefin breathable film backsheet is made of calcium carbonate, silica, clay, titanium dioxide, etc. as inorganic fillers filled with polyolefin, made into a film by calendering or casting, blowing, and then unidirectional or biaxial stretching to form a breathable film , Widely used in baby diapers, women's sanitary napkins, protective clothing, moisture-permeable waterproof materials for construction and other products. Domestic research in this area started late. This paper mainly studies the relationship between the molding process and the performance of polyolefin breathable film backsheet.

1. The effect of stretching temperature on the properties of breathable film backsheet

When the stretching ratio is 2.0, with the increase of the stretching temperature, the longitudinal elongation tends to increase, while the transverse elongation increases slowly and remains at a certain level when the stretching temperature is high. level, and the maximum tensile strength occurs at 85 °C.

As the stretching temperature increases, the air permeability gradually decreases. In general, when the stretching temperature is close to the softening point, the obtained breathable film has better comprehensive performance, good film appearance, basically disappears stripes and softer hand feeling.

2. The effect of stretch ratio on the properties of breathable film backsheet

The elongation of breathable film backsheet decreased with the increase of stretch ratio, and the decrease in the longitudinal direction was obvious, while the decrease in the transverse direction was slower. Within a certain stretching ratio range, the longitudinal tensile strength is basically not affected by the stretching ratio, while in the transverse direction, the strength decreases significantly with the increase of the stretching ratio.

The water vapor transmission rate increases gradually with the increase of the stretching ratio, because the larger the stretching ratio, the larger the micropores of the film and the higher the porosity.

3. The effect of film thickness on the performance of breathable film backsheet

Under the same process, the tensile strength of the breathable film is less affected by the thickness of the film, but the elongation increases with the increase of the thickness; under the same stretching ratio, the porosity has little relationship with the thickness , while the air permeability decreases with increasing thickness.