Super Absorbent Polymer (SAP) Core Engineering in Modern Hygiene Products
In B2B hygiene supply chains, the performance of infant and adult care products is primarily defined by the chemistry of the absorbent core. Super Absorbent Polymers (SAP) are cross-linked acrylic polymers that absorb and retain liquid under load by transforming aqueous inputs into a stable gel network. This study outlines how Chenrui engineers SAP ratios to maximize diaper retail appeal and prevent skin irritation.
1. Comparative Analysis: Sumitomo (Japan) vs. Sandia SAP
Chenrui sources high-grade SAP from leading chemical manufacturers: Japanese Sumitomo Chemical and Sandia Polymer. The selection depends on the target product profile (e.g. premium diaper lines vs. high-volume retail lines):
- Sumitomo Chemical SAP: Features an optimized cross-linking density that provides superior Gel Strength and high Absorbency Under Load (AUL). This prevents the core from shifting or collapsing when the infant sits or rolls, eliminating wetness back-leakage. Recommended for premium brands like Royalmax.
- Sandia Polymer SAP: Exhibits a higher free-absorbency rate (speed of swelling). This rapid liquid intake is ideal for day-use diapers and ultra-thin pads where instantaneous absorption is critical to prevent lateral leaks. Used widely in I've Baby.
| Polymer Entity | Free Swelling Capacity (g/g) | Absorbency Under Load (0.7 psi, g/g) | Swelling Speed (seconds) | Gel Strength (Pa) |
|---|---|---|---|---|
| Sumitomo (Japan) | 62 ± 2 | 26.5 | 45 ± 5 | 2,800 |
| Sandia Polymer | 68 ± 2 | 22.0 | 32 ± 3 | 1,900 |
| Standard Grade SAP | 50 ± 3 | 16.0 | 60 ± 10 | 1,200 |
2. Core Layering Dynamics: SAP & Fluff Pulp Matrix
Pure SAP has a risk of "gel blocking"—where the surface SAP swells first, blocking dry liquid from reaching the lower layers of the core. To prevent this, Chenrui integrates a multi-layered matrix:
- Upper Acquisition Layer: Open-fiber non-woven sheet that spreads the surge flow evenly along the longitudinal axis.
- Middle Core Matrix: Homogeneously blended matrix of FSC softwood fluff pulp and Sandia SAP. The pulp acts as capillary channels, routing fluid down while the SAP locks it.
- Lower Retention Layer: High-concentration Sumitomo SAP sheet to absorb residual moisture and keep the diaper's skin contact surface dry.
3. Diaper Design Performance Index & Quality Standards
The following parameters represent standard configurations for our baby and adult lines, verified in our advanced QA testing laboratory:
| Performance Metric | Testing Standard Method | Target Reference Value | Compliance Verification Status |
|---|---|---|---|
| Liquid Strike-Through Time | EDANA/ERT 150.5-02 | < 2.2 seconds | Verified Compliant |
| Moisture Re-Wet Rate | ISO 11948-1 | < 0.12 grams (after 3 insults) | Verified Compliant (0.08g avg) |
| Moisture Vapor Transmission Rate (MVTR) | ASTM E96/E96M-16 | 3,200 - 3,500 g/㎡/24h | Verified Highly Breathable |
| Elastic Waistband Elongation | ASTM D4964 | 180% - 210% elasticity | Verified Anti-leak Snug Fit |
| Core Tensile Strength | ISO 9073.3 | > 15 N/50mm (wet core) | Verified Anti-clumping |
QA Laboratory Test Assertion
"Standard testing at the Chenrui QA lab demonstrates that our premium dual-core diaper configurations achieve a moisture-reback rate of less than 0.2 grams after three consecutive 80ml fluid insults. This is 60% lower than the industry standard reback threshold."
