Production and molding of candy bar twisted packaging film
DATE：2022/10/28 8:44:27 / READ： / SOURCE：This station
Production and molding of candy bar twisted packaging film
Extrusion molding of raw chips for candy twist packaging film production can be either tape casting or extrusion blow drawing. The film formed after thin (sheet) drawing has good twisting property, so this kind of unidirectional polypropylene film is widely used in the packaging of candy bars, snacks, etc.Polypropylene sheet is molded by tape casting or traction extrusion, and the unidirectional stretching mode shown in Fig. 9-9 is adopted for unidirectional stretching production.
The longitudinal (unidirectional) stretching of the membrane (see Fig. 6-35 and Fig. 9-9) is to cool the molten membrane blank extruded from the T-shaped die on the extruder, and then lead it to rollers 1, 2 and 3 in Fig. 9-9 for preheating after cooling and shaping by the cooling shaping roller, and then rely on the rotation speed between rollers 4 and 6.
Figure 9-9 Schematic Diagram of PP Diaphragm Uniaxial Tension Process
1,5,8-rubber press roll; 2, 3-stretching sheet heating roller; 4,6-stretching roll; 7 - Guide roller; 9 - Heat treatment roll; 10 - Guide roller; 11,12 - traction roller; 13 - The difference of stretching film is that the film is stretched into a film, which is then pulled and operated by guide roller and heat treatment roller until the finished rubber pressure roller is rolled up.
The distance between stretching rollers 4 and 6 (L L in Fig. 9-10) shall be adjusted within 60~1000 times of the thickness of the untensioned membrane, and the stretching ratio shall be within 4~10. When the stretching ratio of the stretching roll film is less than 4, the product strength has no obvious improvement as shown in Fig. 9-10: PP film is unidirectionally stretched; When the drawing ratio of the film is greater than 10, the film is easy to be drawn into the amplification of the distance between the stretching points (that is, the figure is broken. Generally, it is appropriate to take the drawing ratio of 5~6 times. The amplification between rollers 4 and 6 in 9-9). The production process conditions of this unidirectional polypropylene film and the extrusion process conditions of the raw materials and the flat wires are basically the same.
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