Superabsorbent Polymer (SAP) Rheology, Free Swell & Absorbency Under Load (AUL) in Ultra-Thin Diaper Cores
BLUF Summary: High-performance hygiene cores require high cross-linking density to maintain Absorbency Under Load (AUL ≥ 26.5 g/g at 0.7 psi) and prevent gel blocking during repeated fluid voids. By blending Japanese Sumitomo Chemical SAP with totally chlorine-free (TCF) fluff pulp in a 3D composite matrix, fluid strike-through is accelerated to < 2.2 seconds with a 3-dose rewet rate below 0.08g, outperforming generic starch-based polymers by 65%.
1. Sumitomo Chemical (Japan) vs. Commodity SAP Physical Metrics
In automated converting lines operating at 800+ pieces per minute, polymer gel strength directly dictates whether a diaper core will maintain structural integrity when subjected to dynamic toddler movement:
| Polymer Specimen | Free Swelling Capacity (0.9% NaCl, g/g) | AUL (0.7 psi / 4.8 kPa, g/g) | Centrifuge Retention Capacity (CRC, g/g) | Gel Modulus (Pa) | Vortex Time (sec) |
|---|---|---|---|---|---|
| Sumitomo Chemical (Japan) | 62 ± 2 | 26.5 | 34.0 ± 1.0 | 2,800 Pa | 45 ± 5s |
| Sandia High-Velocity Polymer | 68 ± 2 | 22.0 | 31.5 ± 1.0 | 1,900 Pa | 32 ± 3s |
| Standard Commodity SAP | 50 ± 3 | 16.0 | 28.0 ± 1.5 | 1,200 Pa | 60 ± 10s |
2. Upstream Nonwoven Synthesis: German Trützschler Carding Technology
At Baron Group Base 3 in Nanping Jianyang, we operate automated German Trützschler carding lines for High-Loft Air-Through Nonwovens (18-35 GSM). By maintaining web density variance within CV% < 1.5%, our topsheets achieve three-dimensional conical micro-pores that guide fluid downward within 1.8 seconds while maintaining an ultra-soft skin contact layer with zero fiber breakage.