PVC sheet (sheet) extrusion molding
DATE：2022/11/8 8:30:58 / READ： / SOURCE：This station
PVC sheet (sheet) extrusion molding
(1) Raw materials for PVC sheet (sheet) extrusion molding: rigid suspension method SG4 or SG5 PVC resin as the main raw materials; The suspension method SG2 or SG3 PVC resin is used as the main raw material for soft materials, and stabilizer, plasticizer, filler and other auxiliary materials are properly added according to the application conditions of the product to form the raw material formula. The food packaging is made of hard sheet and sanitary PVC resin. See Table 4-8 for the formula of extrusion materials for different plates (sheets). Extrusion molding formula of soft tablets (by weight): PVC SG2 100, tribasic lead sulfate (3PbO) 3, dibasic lead phosphite (2PbO) 1, dioctyl phthalate (DOP) 30, dibutyl phthalate (DBP) 25, PVC plates (tablets) are extruded. The specifications of the extruder are also suitable for colorants.(2) Equipment conditions
The diameter is selected according to the data in Table 7-2. The screw structure is of equidistant gradual change type, with L/D>20:1 and compression ratio of 3. Generally, branch pipe type or screw distributed T-shaped mold is adopted for the selection of mold structure.
(3) Forming process
① See Chapter 4 for mixing process parameters and requirements of raw materials.
② Extrusion plasticizing raw material barrel temperature.
a. The feeding section of hard board (sheet) is 120~130 ℃, the plasticizing section is 130~150 ℃, and the homogenizing section is 160~180 ℃.
b. The feeding section of soft board (sheet) is 100~120 ℃, the plasticizing section is 130~140 ℃, and the homogenizing section is 150~160 ℃.
③ Forming mold temperature
a. The middle part of the hard board (sheet) is 155~165 ℃, and the two ends are 170~180 ℃.
b. The middle part of the soft plate (sheet) is 145~155 ℃, and the two ends are 160~170 ℃.
④ Three roller calender roller temperature
a. 70~80 ℃ above, 80~90 ℃ in the middle and 60~70 ℃ below the hard board (sheet).
b. 60~70 ℃ on the soft board (sheet), 70~80 ℃ in the middle, and 50~60 ℃ in the lower.
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