Monographs on linear low-density polyethylene film

日期:2020/1/9 9:51:27 / 阅读: / 来源:本站

2.2.3 Monographs on linear low-density polyethylene film

As mentioned earlier, because linear low-density polyethylene has higher tensile strength, impact strength, tear strength, puncture resistance, and properties than low-density polyethylene, and has good processing properties such as heat-sealing of films, it has a wide temperature range. Only slightly less transparent. The density of the same density polyethylene, the film can be 20% to -25% thin. Therefore, it has stronger market competitiveness than LDE. . The types of linear low-density polyethylene are almost the same as those of low-density polyethylene, so its standards have not been formulated separately, and they are generally implemented with reference to similar film standards of low-density polyethylene. It is necessary to blend linear low-density polyethylene and low-density polyethylene into a film.

In terms of processing methods, it is mainly blown film, followed by extrusion cast film, co-extruded composite film, extrusion coated film,

In addition, there are rolled films and biaxially stretched films.

Film characteristics and uses are similar to low-density polyethylene films, mainly general blown films, heavy packaging films, liquid packaging films, heat-shrinkable films, stretch-wound films, microporous breathable diapers, silage films, cast films, and Calendered sea film

high

Etc. will be summarized below.

2.2.3.1 Linear low density polyethylene blown film for general packaging

1.Application and resin selection of LLDPE blown film for general color installation

LLDPE film for general packaging, film thickness is 0.08 ~ 0.35mm, general light packaging, film thickness is 0.015 ~

0.040 with automatic packaging film bag, film thickness 0.060-0.150m; its use is the same as IDPE; both can pass

nm:

Application, and each has its own emphasis according to its performance and use requirements. If good transparency is required, LDPE film is generally used. When high strength is required, LDPE film is used. When automatic packaging requires certain rigidity, LLDPE film is used. When the strength requirements are the same, the LLDPE film can be thinner. Big

For example: garbage bags, garbage bags made of LLDPE i film are thicker than garbage bags made of LDPE with the same specifications.

Can reduce 13%, but the tear strength can still reach the level of LDPE. The puncture resistance is good. Another example is bread packaging film. LLDPE film has been widely used in developed countries such as Europe. Compared with the original LDPE film, the thickness can be changed from

0.03mm to 0.02mm. Mailing film bags and clean film bags can be blown with a mixture of LLDPE and LDPE

The film is made of high heat seal strength, good resistance to environmental stress cracking, and can be thinned at the same time, suitable for FFS (molding, filling and sealing) mechanical packaging to prevent cracking of the seal.

Almost all LLDPE films for packaging use blow molding.

General packaging LLDPE blown film has special resin grades, which are more common, and its MR value is 0.5-4g10min. Or bigger, choose according to processing and use requirements, see the relevant resin grade manual for details.

2. Processing aid and processing aid masterbatch for LLDPE

(1) The differences between LDPE film and LDPE film processing are as described in Section 2.2.2.2 above. At the same melt flow rate, LLDPE has a higher viscosity in extrusion processing than LDPE. The tensile viscosity is lower than that of LDPE. Due to the higher viscosity during extrusion, the power consumption of the extruder is significantly increased, and the screw torque is increased to produce a higher pressure for a certain head. In this case, using the original equipment for processing LDPE film, to achieve LDPE output, the equipment must be transformed or special equipment must be used. This will cost a lot of money. Another method is to use a method of adding a processing aid.

(2) Processing aids for LLDPE LLDPE processing aids can be roughly divided into three categories

) Chlorine bomb: Because chloroplast is more polar than polyethylene, it is incompatible with LLDPE. Most of the unmelted fluorine bombs form a fluorine bomb film on the inner wall of the barrel to effectively lubricate the mold. Head wall, forming a lubricating layer to reduce molten metal

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