Today,
Stretch Film has been widely used in China's industrial production. Stretch film is an important material for protecting goods. It is no exaggeration to say that if the stretch film does not have a reliable protective effect on the packaged goods, then it will lose its use value as a packaging material, and it will fail in material selection. The protective function of stretch film on cargo is varied. Different commodities and different packaging methods have different requirements for the protection function of stretch film. Described here are just some of the main features to consider in general. So what are the details that reflect the good protection of the goods by the stretch film? The specific contents are as follows:
1. Reliable mechanical maintenance effect
Reliable mechanical maintenance effects include avoiding cargo damage and contamination caused by leakage of goods in the package or foreign objects entering the package. The functional indicators that directly reflect the mechanical maintenance function of the stretch film are mainly the mechanical strength of the stretch film, such as tensile strength, tear strength, drop impact strength (drop impact), puncture resistance, etc. The larger the strength value, the better the curing effect.
2. Adhesion strength
Good bond strength is also a necessary condition for the stretch film to reliably maintain goods. If the adhesive strength is insufficient, the gap will become the fatal defect of the stretch film, and the stretch film will lose its maintenance effect on the goods due to the damaged packaging. Ordinary biaxially oriented polypropylene film has good mechanical strength, but due to its poor adhesion function, biaxially oriented polypropylene monolayer film is generally not used for bag making. When bag making is required, a composite stretched film based on a biaxially oriented polypropylene film containing a heat-sealing layer (Xing or CPP) needs to be selected. The adhesive function of the stretch film is usually expressed by the adhesive strength, namely N/15mm, the higher the adhesive strength, the better the adhesive function.
3. Other Features
Among the other functions of commodity maintenance, the isolation function and the shading function are most needed.
Isolation refers to the effect of stretching the film to avoid oxygen, carbon dioxide, nitrogen and other gases, as well as aroma, water vapor and other substances; when the scope is not clear, it generally refers to the isolation of non-polar gases such as oxygen, carbon dioxide, and nitrogen. For many commodities, especially food, the thermal insulation function of stretch film is an important factor for the long-term effective storage of packaged commodities. Different products have different requirements for the insulating function of the stretch film.
The shading property of stretch film is also important for the packaging of some commodities. Light, especially ultraviolet light, is an important cause of discoloration, fading, and photo-oxidation of certain substances, which should be paid attention to. The light-shielding property is measured by the light transmittance at a given wavelength, which is high in light transmittance and poor in light-shielding property.
