Factors affecting the quality of heat seal trimming of PET/VMCPP composite film

When the PET/VMCPP composite film is packaged at a high speed on a rotary knife automatic packaging line, there are always quality problems such as heat sealing and trimming, and cuts, etc., resulting in rough cut edges of the packaged product, and even the independent packaging should be stuck at the cut portion. connected together. When such quality problems occur, the commonly used solution is to reduce the production speed, so as to prolong the cutting time of the rotary cutter and make the trimming neat, and reducing the production speed is bound to change the original intention of reducing the overall cost of packaging.

How to solve the contradiction between PET/VMCPP composite film's packaging quality and high-speed packaging quality issues, what are the main factors affecting the quality of PET/VMCPP composite film heat-sealing and trimming? In order to solve the above-mentioned contradiction, this article will discuss the factors affecting the quality of PET/VMCPP composite film heat sealing trimming from the aspects of packaging material production process and cutting knife working conditions.

Stiffness of VMCPP film

The stiffness of the VMCPP film is closely related to the quality of the heat seal trimming of the PET/VMCPP composite film. To ensure that the PET/VMCPP composite film has a good quality of the heat seal trimming, the stiffness of the VMCPP film must be moderate.

Melting temperature of VMCPP film

The melting temperature of VMCPP film also has a certain influence on the quality of the heat seal trimming of the PET/VMCPP composite film. Therefore, in the process of casting VMCPP film, the resin material of each layer should use the resin with the highest melting point relatively low, or blend some elastomer resins with higher melting index and lower melting point.

Peel strength of PET/VMCPP composite film

The PET/VMCPP composite film with low peel strength cannot prevent the VMCPP film in the heat sealing zone from being deformed under the action of the rotary cutter in time, making the thermal cut-off of the PET/VMCPP composite film poor, resulting in threading and cutting. Constantly wait for the emergence of problems. Conversely, when the peel strength of the PET/VMCPP composite film is high, the hot cuttability is better.

Stiffness of PET/VMCPP Composite Film Adhesive Layer

In order to avoid the problems of PET/VMCPP composite film heat-shrinking and trimming, the adhesive should be selected after compounding, or the content of curing agent in the adhesive should be increased to ensure PET/ The peeled surface of the VMCPP composite film is not sticky.

Knife temperature

In the process of heat sealing trimming, the temperature of the cutter is higher than the melting point of the VMCPP film resin material, so that at the instant of heat sealing trimming, the VMCPP film at the cutter will be in a melted state, and the lower its melt strength, the more severe the cut off. Well, the more neat the trimming is.

Cutter pressure

Increasing the pressure of the knife can effectively ensure the cutting and regularity of the heat seal trimming. It should be pointed out that excessive heat sealing pressure not only results in excessive thinning of the VMCPP film in the heat seal area, resulting in a decrease in the heat seal strength, but also wear of the heat seal mold and the cutter.

(From Printing Technology Packaging and Decoration" May 2012)