The performance of different kinds of plastic packaging film is different. When choosing, we need to follow some basic functions of plastic packaging film, mainly for the protection function of products, promotion function, adaptability to packaging machinery and other applications. Considering the special needs, it is divided into the following 13 articles, which we call 13 reference standards:
1. Protection function
As a packaging material, the protective function of plastic film is the most important and basic function. If the plastic film does not have a reliable protective effect on the packaged product, causing damage or devaluation of the product, it loses its use as a packaging material. The protective function of plastic film on commodities is multi-faceted. Different products and different packaging forms have different emphasis on the protection function of plastic packaging film.
2. Mechanical protection
Prevent the leakage of goods in the package or the damage and pollution of the goods caused by foreign substances entering the package. The performance index directly reflecting the mechanical protection function of the plastic film is mainly the mechanical strength of the film, such as tensile strength, tear strength, falling impact strength (drop impact) and puncture strength.
3. Good welding strength
The welding strength is also a necessary condition for the plastic film bag to reliably protect the product. If the weld strength is insufficient, the weld will become the Achilles heel of the plastic film bag, and the plastic bag will lose its protection to the product due to the crack of the weld.
4. Barrier performance
The barrier property refers to the performance of the plastic film to prevent the transmission of gases such as oxygen, carbon dioxide, nitrogen, and the like, aroma, water vapor, etc., and when it is not clearly defined, it generally refers to the barrier of non-polar gases such as oxygen, carbon dioxide, and nitrogen. The effect of the plastic film on the product display is closely related to the light transmittance, haze, gloss, antistatic property and printing property of the film itself, and it is necessary to pay attention to the light transmittance and the haze.
5. Light transmittance and haze
Light transmittance and haze are important indicators for determining the visibility and clarity of the packaged goods, and the relationship between the display effects of the products is particularly large. Both light transmittance and haze are expressed as a percentage. The larger the value of light transmittance, the better the transparency of the film. The larger the haze, the greater the turbidity of the object observed through the film, that is, the sharper the sharpness.
Glossiness is the ability of a plastic film to reflect light when exposed to light, expressed as a percentage of the brightness of the sample reflected in the direction of normal reflection relative to the standard surface.
7. Antistatic properties
With the rapid development of the electronics industry, electronic circuit boards are becoming more and more integrated. Packaging products with antistatic film can prevent static damage to the integrated circuit.
8. Good smoothness
Good smoothness is conducive to the smooth movement of the film on the packaging line during packaging, avoiding the damage caused by excessive resistance during its movement. The smoothness of the film can be described by the magnitude of its coefficient of friction. The smaller the coefficient of friction, the better the smoothness performance.
9. High temperature resistance
It is often necessary to consider the high and low temperature resistance of the film, such as refrigeration, especially the use of plastic packaging film for frozen foods, which needs to have good low temperature resistance; the plastic packaging film for cooking food needs to have good high temperature resistance and the like.
10. Hygienic performance
When packaging food or pharmaceutical products, the selected plastic packaging film must have good hygienic properties and meet the requirements of the relevant national health standards to ensure that the plastic film does not cause pollution to the packaged goods.
11. Air tightness
It has good air tightness and can effectively block the exchange of gas inside and outside the packaging container, which is necessary for most products.
12. Moisture resistance
Good moisture resistance is a means to effectively protect the commodity. Generally, the moisture resistance of the plastic film increases with the increase of the thickness, and becomes smaller as the temperature decreases.
13. Oil resistance
For oily foods, such as sausages and bacon, the packaging film must be resistant to oil, otherwise it will affect the quality of the product.