Plastic bags are widely used in department stores and corner stores. The key control points of the plastic bag in the film blowing process are: temperature, rotation speed of the main machine, traction ratio and film blowing ratio. Today, Jinan plastic bag manufacturer carefully introduces the precautions in the film blowing process for you, hoping to help you!
1. Extruder temperature
When blow molding LDPE, the extrusion temperature is generally controlled between 160 ℃ and 170 ℃, and the average temperature of the die head must be ensured.
High extrusion temperature: the resin is easy to synthesize and the film is brittle, especially the longitudinal tensile strength is obviously reduced.
Low extrusion temperature: poor plasticization of resin, low tensile strength of film, low appearance gloss and transparency, melting of atomic nucleus due to wood grain
2. Blowing ratio of plastic bags
Film blowing ratio is a link in the process of film blowing. It controls the width and thickness of film blowing, as well as the number and tensile ratio of roots.
At the same time, the blowing ratio also affects the transverse tensile strength and the average thickness of the film. The expansion ratio can improve the transverse strength of the film, but it should not be too large, otherwise it is easy to form the film bubble instability, and the film is easy to fold, at the same time, the thickness of the film will show uneven. In general, it is suitable to control the film blowing ratio of LDPE at 2.5-3.0
3. traction ratio
牵引力比是指膜的牵引力速度与管环的挤出速度之比。牵引比增加,然后纵向强度也会进步,和薄膜厚度变薄,但如果牵引比太大,膜的厚度难以控制,因此可能会让这部电影打破,形成段电影现象,比普通聚乙烯薄膜牵引控制在4 - 6之间为宜。
Traction ratio refers to the ratio of the traction speed of the membrane to the extrusion speed of the pipe ring. If the traction ratio increases, then the longitudinal strength will also improve, and the film thickness becomes thinner, but if the traction ratio is too large, the film thickness is difficult to control, so this film may be broken, forming a segment film phenomenon, which is better than that of ordinary polyethylene film traction control between 4 - 6.