1、 Core technical difficulties

1. Multi component dispersion and interface compatibility challenges (most common)

Inorganic fillers (calcium carbonate, talcum powder, glass fiber, nano powder), pigments, flame retardants are easy to agglomerate; The polarity difference between polymers is large (such as PP non-polar, PA/PBAT polar), and the two phases are prone to phase separation, resulting in microscopic defects, mechanical strength fluctuations, white spots, and frost.

The high filling formula (calcium carbonate>70%) has less resin matrix, making it difficult to fully encapsulate the powder. The melt flowability is poor, and the mold head pressure fluctuates violently, resulting in broken bars and uneven particle size.

Fiberglass reinforcement system: High shear will cut the fiberglass too short, resulting in a decrease in strength; Insufficient cutting results in floating fibers and poor interface bonding.

2. Difficulties in thermal degradation and temperature control of thermosensitive materials

Polymers (PP, PLA, PBAT, PVC) are sensitive to shear heat; High shear of the screw will generate local hotspots, and the actual temperature will be 15-25 ℃ higher than the set temperature, causing molecular chain breakage, yellowing, MFR (melt index) drift, and unstable batch performance.

Recycled materials: multiple processing aging, complex impurities, easier degradation, black spots, and large color differences;

Biodegradable material PLA/PBAT: high temperature and trace moisture will hydrolyze, causing a sharp drop in molecular weight and brittle particles.

3. Feeding stability, exhaust and volatilization issues

Powder fillers are fluffy, prone to bridging, raise dust, cause weight loss and feeding fluctuations, and cause formula ratio drift, resulting in inconsistent batches;

Additives, monomer residues, moisture, and low molecular weight volatiles, if vacuum devolatilization is insufficient, the finished particles may have bubbles, pores, frost, and VOC exceeding the standard (a pain point for low VOC PP in automotive interiors).

4. Granulation molding and particle consistency

Pulling strips with water cooling is prone to breakage and adhesion; Underwater particle cutting is prone to sticking to the blade, uneven particle size, and porosity; High filling/high viscosity melt, uneven die discharge flow rate, and large particle size variation directly affect downstream blown film and injection molding stability.

5. Pain points of wear resistance, energy consumption, and production flexibility

High filling powder has strong abrasion resistance, fast wear of screws, barrels, and molds, and high maintenance costs; Traditional single screw has high energy consumption; When producing multiple varieties in small batches, the time for material replacement and cleaning is long, and there is a lot of waste.

6. Unique difficulties of recycled materials

The sources of raw materials are mixed, with many impurities and significant fluctuations in composition; The melt index, ash content, and moisture content vary greatly among different batches, making stable granulation much more difficult than new materials.