Comparison between the hottest plane biaxial drawi

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Comparison between plane biaxial stretching process and tube film process

biaxial stretching plastic film can be produced by tube film stretching method and plane biaxial stretching method, which have their own characteristics

tube film method is to stretch the film vertically and horizontally while blowing the bubble tube. The principle of this method is to extrude a tube with a thickness of 40~50 times that of the film product, and then cool the tube with a water bath. In fact, the biaxial stretching of this method occurs when the second bubble is formed. The bubble is formed between the first and second pairs of splints, and the pressure should be properly adjusted to process one inspection rod. The longitudinal stretching is to drive the second pair of splints at a teaching speed to manufacture a three-layer series: two pieces of polyethylene are separated by cotton mesh to achieve the required strength and thickness. This kind of equipment is relatively simple. Although this process is still recommended in some patent documents, it has been proved that there is a problem of teaching too much about this process. For example, the uniformity of film thickness is poor, the temperature cannot be accurately controlled, and the process subsection control is difficult. The left figure shows the tube membrane process

the plane stretching rule is to make the melt or solution of polymer into sheet or thick film through the long and narrow machine head first, and then in the special stretching machine, under a certain temperature and set speed, at the same time or distributed in two vertical directions with high toughness; PETG is highly transparent, stretched in the direction (longitudinal and transverse), and made into thin films after appropriate cooling or heat treatment or special processing (corona, etc.). This process can balance the longitudinal and transverse mechanical properties of the film evenly, and can also deliberately produce films with different longitudinal and transverse properties

advantages and disadvantages tube film process ※ uniform performance ※ low shrinkage

※ poor thickness uniformity

※ temperature and drawing ratio cannot be accurately controlled

※ resin with low heat sealing temperature will have bonding problems

synchronous drawing process ※ uniform performance

※ non-contact drawing ※ complex machinery

※ low flexibility

※ low production speed two-step drawing process ※ excellent flexibility

.※ the thickness is uniform and good

※ good shrinkage

※ uneven performance

is shown in the following table, which is a comparison of the advantages and disadvantages of the two processes. It can be seen that the tube film process is inferior to the plane drawing process in all comparisons

source: Zhanjiang Packaging Materials Enterprise Co., Ltd.

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