Metallocene Polypropylene Nonwoven Fabric Production

The patent applies parameter changes by precisely controlling the molecular weight distribution (PDI) of metallocene homopolypropylene resin within 1.8-2.5, weight average molecular weight between 80,000-150,000, and melt index between 15-30 g/10min. These parameter optimizations enable the resin to produce uniform thin fibers while achieving improved stretchability (40-80% elongation) and water pressure resistance (150 mmH2O or more), resolving the contradiction between fiber uniformity and mechanical strength.

The patent applies the extraction principle by removing the Ziegler-Natta catalyst system and exclusively using metallocene catalyst for polymerization. This eliminates the source of high xylene soluble content and TVOC emissions. The metallocene catalyst produces resin with PDI of 1.8-2.5 and xylene soluble content of 3% or less, while maintaining excellent mechanical strength through optimized molecular weight control (weight average molecular weight 80,000-150,000), thus extracting the harmful catalytic system while preserving desired properties.

The patent resolves this contradiction through parameter changes by optimizing the molecular weight distribution width (PDI) to a specific range of 1.8-2.5, which is narrower than conventional resins but not excessively narrow. Combined with controlling weight average molecular weight at 80,000-150,000 and melt index at 15-30 g/10min, these parameter adjustments enable the production of uniform thin fibers that simultaneously achieve water pressure resistance of 150 mmH2O or more, overcoming the limitation of narrow distribution resins.