One-step compounding process of PP/LFT composites

One-step compounding, that is, to complete the granulation and compounding process of thermoplastics, glass fibers and other additives in one production line, thereby preparing thermoplastic/LFT composite products.

Its principle diagram is shown in the figure.

1—drive motor;

2—drive shaft;

3—gearbox;

4—long glass fiber bundle;

5—Hopper;

6—thermocouple;

7—melting cylinder;

8—External heater;

9—screw;

10—feed inlet;

11—split cone;

12—die head;

13—Cavity;

14—heater;

15—fiber cutting device;

16—fiber feeding device;

17—rack;

18—hydraulic system;

19—Control system

PP is added in the feeding hopper 5, and is moved forward and plasticized by the push of the screw 9. The long glass fiber bundles 4 are drawn into the fiber cutting device 15, cut to a certain length, and then enter the side feeding device 16, and then enter the barrel under the forced feeding of the side feeding device to be mixed with the molten thermoplastic resin. Under the compounding action of the screw, the thermoplastic resin and the glass fiber are uniformly dispersed, and the compounded PP/LFT composite material is injection-molded, and the online compounding of the PP/LFT composite material is realized. At present, the mainstream trend of long glass fiber is to develop on-line compounding, especially for the production of automotive composite materials, which is widely used in European and American automotive companies.

This technology can improve the production efficiency of products and save energy consumption, and greatly retain the length of glass fiber, so that the mechanical properties of products can be optimized.

In the one-step compounding process, both LFT and PP are compounded through the control system and on the basis of a large number of experiments to achieve precise compounding of materials; Among them, melt plasticization is the most critical step, which can directly affect the appearance, mechanical and physical properties of the final product. The screw design, the internal pressure of the barrel and the compression distance play a major role in the plasticizing effect of the process; At the same time, the internal structure, pressure and holding time of the mold have a certain influence on the orientation and dispersion of the glass fiber.

Main conclusion

(1) Using the "one-step compounding process", there is great innovation in the process, saving energy, reducing consumption and reducing logistics costs.

(2) Segmented configuration of screw structure + wave-like dispersion design, faster and better mass and heat transfer, controllable melting of polymers, and improved dispersion of melt and glass fibers.

(3) The holding pressure has no obvious effect on the overall mechanical properties of the PP/LFT composite, and can be appropriately increased.

(4) The increase of the melting temperature leads to the decrease of the melt viscosity and the decrease of the shear force of the LFT, and the retention length of the LFT increases with the increase of the temperature.

(5) The notched impact strength and tensile strength are greatly affected by the screw speed, which both increase with the increase of the screw speed, and then decrease. It is better to control the screw speed to a medium speed.

(6) Notched impact strength and tensile strength are sensitive to the value of back pressure. The greater the back pressure, both will gradually decrease, and the back pressure should be reduced.

Nanjing Haisi Extrusion Equipment is a professional manufacturer of plastic compounding machine. We are well experienced in nylong compounding, masterbatch making..Any interest please feel free to contact us!