Our raw materials--Application of LLDPE in plastic films.

LLDPE is a linear molecule with no or few long branched chains, and LLDPE for membrane is a polymer with narrow molecular weight distribution, compared with LDPE, LLDPE significantly improves tensile strength, tearability, puncture, and has better heat and cold resistance. In terms of processing performance, LLDPE has poor sensitivity to stress, that is, under the high shear stress of extrusion processing, the melt viscosity is high, larger torque, higher melt temperature and die pressure are required. And it is easy to melt rupture: but it does not harden when the bubble is drafted, it has good stretchability, and the draft ratio is 25~150. Under large tensile deformation, it is not highly oriented and does not produce a high degree of bidirectional imbalance.Thin films are the area where LLDPE is used the most. Among them, it is especially widely used in agricultural film, and it is excellent in winding stretch film.

Stretch wrapping film is also called stretch elastic retraction wrapping film. It is a kind of single-sided (or double-sided) sticky plastic film that can stretch and wrap the covered items tightly so that it does not disperse and be damaged and contaminated during storage and transportation, and at the same time, due to high transparency, it is also convenient to identify the covered items and reduce delivery errors. It uses PE as the basic raw material and is produced by casting method or blow molding method through ingredients.

Scientists studied the viscous relaxation of linear low-density polyethylene (LLDPE) stretched winding film, discussed the effects of viscous masterbatch addition, film cooling rate, molecular weight of viscous additives, storage temperature and different film-making process methods on the self-adhesiveness of the winding film, and found that after the preparation of LLDPE stretch-winding film, the surface viscosity of the film underwent a relaxation process, and the viscous relaxation reached relaxation equilibrium in about 15 days. The viscosity of the membrane surface increases with the increase of storage temperature or the increase of the amount of viscous masterbatch added during film making, and the film making process has a significant impact on the viscosity of the membrane surface, and compared with the blow molding method, the casting method is easy to obtain a tensile winding film with good viscosity.

This is because cast line production has the advantages of uniform thickness and high transparency, which can be applied to the requirements of high magnification pre-tension. Since single-laminar casting cannot be single-sided adhesion, the application field is limited. Single and double laminar casting is not as wide as three-layer casting in material selection, and the formula cost is also high, so the structure of three-layer co-extrusion is ideal, and the high-quality stretch film should have the characteristics of high transparency, high longitudinal elongation, high yield point, high transverse tear strength, and good puncture performance.

Therefore, when choosing stretch film products, it is recommended that customers use stretch film of LLDPE raw materials, which has obvious advantages.