What Factors Will Affect The Viscosity Of The Stretched Film?
At present, stretch film is widely used. Tensile film will be used in general logistics industry, transportation industry and goods storage in factories. LLDPE stretch film, also known as LLDPE elastic film/packaging film, is a transparent, elastic and strong, non-toxic and non-hazardous soft polyethylene plastic film, in line with international environmental health standards. LLDPE stretch film has the advantages of toughness, impact resistance, transparency and self-adhesive, whether used for the collective packing of products or cargo cardboard, can be moisture-proof, dustproof and reduce labor, improve efficiency, to protect products and Reduce the cost of the purpose.
One of the important characteristics of stretched film is that the viscosity of the stretched film is better.
What factors will affect the viscosity of the stretched film?
- The effect of molecular weight on the viscosity of stretched film. Tensile films with different molecular weights will have different adhesion properties. PIB with high molecular weight makes the film have higher peel adhesion, but with the increase of PIB molecular weight, the bonding adhesion will be weakened. If the molecular weight is too low, the volatility will be higher, which will lead to too short viscosity retention time. Therefore, choosing the appropriate molecular weight PIB can make the stretched film have properties.The effect of molecular weight distribution on tensile viscosity is considered to be related to the molecular chain action of macromolecular components. That is, the larger the proportion of molecular chains with high molecular weight, the smaller the tensile viscosity.Studies have shown that polyimide with a number average molecular weight of about 1300 is more suitable for adding self-adhesive properties to stretch films.
- The effect of the addition amount on the viscosity of the stretched film. The viscosity of the stretched film is positively correlated with the amount of PIB added. However, when the addition of PIB exceeds 3%, the increase of self adhesion of the stretched film becomes negligible. If you continue to increase the amount of PIB, PIB will precipitate on the surface of the film, resulting in uneven self viscosity of the film, and even the film is difficult to open. In order to ensure the performance of the stretched film and consider the cost of raw materials, the addition of PIB should be controlled between 1% and 3%.PIB has an exudation process that usually takes about three days to wrap the film surface before satisfactory adhesion is achieved.
- Effect of storage temperature of stretched film on viscosity. The migration speed of PIB is related to the storage temperature. With the increase of ambient temperature, the migration speed and viscosity of PIB increased. Therefore, in order to achieve the required tensile film viscosity, it should be stored at a higher temperature. Generally, it should be stored for a week to meet the use requirements. However, if it is stored at a temperature higher than 30 ℃ for a long time, PIB will precipitate a lot, which is easy to cause the film size head or paper core to fall off. Therefore, after the viscosity requirements are met, the stretched film should be kept in the range of -15 ℃ ~ 40 ℃.Polyisobutylene is a viscous liquid substance. When polyisobutylene and polyethylene are co-extruded, the material does not extrude smoothly. Special extrusion equipment, such as an extruder with a forced feeder in the hopper, is required to force feed the mixture of LLDPE and PIB, or special extruders capable of pumping viscous liquids can be used to pump PIB. to facilitate production, a highly concentrated polyisobutylene tackifier masterbatch has been developed for the production of polyethylene stretch films. This masterbatch is made by mixing polyisobutylene and polyethylene in a certain ratio. It is similar in shape to various masterbatches commonly used in the production of plastic products, has good flowability and is easy to use.
To sum up, the above are the main effects that affect the viscosity of stretched film. I hope it will help you. If you want to know more about stretch film products, please visit our website.