Stretch film is strong, has high impact resistance and penetration strength, good self-adhesion, transparency, does not expand the volume of the goods after packaging, can be shockproof, moisture-proof, and strong protection, is a very popular form of packaging internationally. The purpose of PE stretch film is to wrap one or more solid articles with thin flexible packaging materials. The stretch film can not only improve production efficiency, but also prevent damage to the goods during handling, and prevent dust. Moisture and cleaning effect. So what process conditions are needed to produce stretched film? As a professional PE stretch film manufacturer, the following briefly introduces the process conditions required to produce stretch films.

1. Casting production is narrow due to the long flow channel, and the flow speed is fast. The melt temperature range is generally controlled between 250 ° C and 280 ° C, the temperature of the casting cooling roller is controlled between 20 ° C and 30 ° C, and the winding tension should be low. Generally within 10kg to facilitate the migration of the adhesive and reduce the internal stress of the finished film.

2. Control of physical and mechanical properties: high transparency is conducive to the identification of goods; high longitudinal elongation is favorable for pre-stretching and saves material consumption; good puncture performance and transverse tear strength allow the film to be stretched at high stretch ratios It does not break when it encounters sharp corners or edges of the goods; the high yield point makes the packed goods more secure.

3. The film produced by the casting method has high transparency. With the increase of the number of comonomers of the material, the length of the branch chain increases and the crystallinity decreases. The "twisting or kinking" effect of the resulting copolymer increases, so the elongation increases. , Puncture strength and tear strength are also improved. MPE is a high stereoregular polymer with a narrow molecular weight distribution, which can accurately control the physical properties of the polymer, so there is a further improvement in performance; and because of the narrow molecular weight distribution of MPE, the processing range is also narrow, and the processing conditions are difficult to control, usually Add 5% LDPE to reduce the melt viscosity and increase the flatness of the film.

4. Control of stickiness: Good stickiness makes the packaging film layer and layer outside the goods stick together to make the goods firm. There are two main ways to obtain the stickiness: one is to add PIB or its masterbatch to the polymer; another One is to blend VLDPE. PIB is a translucent viscous liquid. Direct addition requires special equipment or modification of the equipment. Generally, PIB master batch is used. PIB migration has a process, which usually takes three days. In addition, it is also affected by temperature. When the temperature is high, the viscosity is strong; when the temperature is low, it is not very sticky. After stretching, the viscosity is greatly reduced. Therefore, the finished film is best stored in a certain temperature range (suggested storage temperature is 15 ℃ ~ 25 ℃). Blended with VLDPE, the viscosity is slightly worse, but there are no special requirements for the

equipment. The viscosity is relatively stable and is not controlled by time, but it is also affected by temperature. When the temperature is higher than 30 ° C, it is relatively viscous. By adjusting the amount of adhesive layer LLDPE to achieve the desired viscosity. This method is mostly used for three-layer coextrusion.