Waste plastic granulation technology - cutting materials

After the waste plastics have been cleaned and dried, the pellets are generally granulated according to the characteristics of the resin and the molding conditions before forming.

The granulation process can be divided into two major categories: cold-cut granulation and hot-cut granulation. Generally, different granulation techniques for plastics are not the same, but the same kind of plastics can also use different granulation processes because of different molding equipment and processes. The characteristics of different granulators are shown in Table 3-5.

1. Cold-cut granulation of flakes and strands Melts lead from the plasticizing equipment to flakes (eg double-roll mills) or strands (eg extruders). Cooling water tank cooling, after the dehydration roller, with the traction roller into the pelletizer at a certain speed, the material traction speed does not exceed 60 to 70m/min, the number of bars does not exceed 40, the size of the pellets The length is determined by the pulling speed and feed speed. The quality, surface quality, gloss, color, and air bubbles of the granulation can be continuously tested on the online material. The advantage of this process is that the operation is simple and the pellets do not stick to each other. The disadvantage is that relatively large space is required.

Applicable materials and characteristics are shown in Table 3-5.

Granulation method

Yield
(kg/h)

Applicable materials

Pellet diameter
(mm)

Length (mm)

Pellet shape

main feature

Cold granulation

Sheet material

5~1000

PE, PP, ABS, PVC, PA and others

1~6

1~6

Cube

Easy start, poor cut shape, poor pellet flow

Line material

5~1000

PE, PP, ABS, PS, PA and others

1~6

1~6

Cylinder

Suitable for a variety of resins, large output, no post-drying, air-cooled

Hot granulation

Center pellet air cooling

20~100

PE, PP, etc.

4~6

1~2.5

Cylinder

Simple operation, good particle shape, low cutting power, limited to PVC or high viscosity material extrusion

Center granulation water cooling

20~600

PE, etc.

2.5~6

1~3

Go chess cylinder

Prone to splicing of pellets, simple operation, good operating environment, mass production

Eccentric granulation water cooling

20~3000

PE, etc.

2~6

1~3

Go chess cylinder

Small nose, high output, relatively large cutter

Milling ring cutter

10~1000

PP, PE, ABS, PVC, PS, etc.

1.5~6

1~3

Go chess cylinder

Almost suitable for pelletizing all thermoplastics

Water ring cutting

500~5000

Almost all thermoplastics

1.5~6

1~3

Go piece sphere

Suitable for high volume applications, suitable for all thermoplastic materials