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 become the material, knowledge and technical basis for the further development of instruments and meters. These two production processes have their own characteristics

plane stretching method can be divided into unidirectional stretching method and plane biaxial stretching method. The tube film method is divided into plane expansion stretching method and blow molding method. The pipe film method mainly produces agricultural film, mulching film and general packaging materials; Using plane biaxial stretching method to produce high-quality and good performance films such as packaging, tape, electrician, film, etc. Due to the excellent performance of planar biaxial tensile film and the wider application range of products, the development speed of this process is much higher than that of tube film method

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 under appropriate pressure. The longitudinal stretching is achieved by driving the second pair of splints at a faster speed. 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, that is, when r1=r2=r3=r4

the plane stretching rule is that the melt or solution of polymer is first made into a sheet or thick film through a long and narrow machine head, and then stretched in a special stretching machine at a certain temperature and a set speed at the same time or in two vertical directions (longitudinal and transverse), and then made into a film after appropriate cooling or heat treatment or special processing (corona, etc.). This is just like heating resin for optimizing activities and pre forming. 1. Metal tensile testing machine must ensure the smoothness of gears in the process of application, and avoid dry transmission at the juncture of movement, which will increase wear and tear over time Excessive addition of smooth oil will also stick a lot of dust, so it is essential to ensure the cleanness and hygiene of the control room of the metal tensile testing machine The impregnation of parts is very necessary. One kind of 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

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



tube film process

※ uniform performance

※ low shrinkage

※ poor thickness uniformity

※ temperature and drawing ratio cannot be accurately controlled

※ low heat sealing temperature resin will have bonding problems

synchronous drawing process

※ uniform performance

※ non contact stretching

※ low flexibility

※ low production speed

two-step drawing process

※ excellent flexibility

※ uniform thickness

※ good shrinkage

※ uneven performance

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