ADL

The acquisition and distribution layer sits immediately beneath the topsheet of disposable absorbent products, sandwiched between the surface facing the skin and the main absorbent core. Its job is to move liquid away from the topsheet as fast as possible, preventing pooling, rewet, and the sensation of dampness. Without a functioning ADL, liquid sits on or near the skin surface, reducing perceived dryness and allowing bacterial growth.

ADLs are typically made from nonwoven fabrics with high capillary pull and lateral wicking speed. Common materials include thermally bonded polypropylene or polyester blends, often combined with superabsorbent polymer (SAP) particles embedded directly into the web. Basis weights range from 40 to 120 gsm depending on the product type and expected fluid load. The fabric structure uses low-density regions and crimped fibers to create tortuous paths that move liquid horizontally across the layer while maintaining vertical flow toward the core.

Performance is measured by several metrics. Acquisition speed tests how quickly the layer pulls a fixed volume of fluid from the topsheet; competitive products target 10 to 60 seconds for a standard 2 mL dose. Distribution efficiency measures how uniformly liquid spreads across the core area; poor distribution creates dry spots and concentrated saturation zones that fail prematurely. Rewet testing determines how much liquid migrates back toward the skin after initial absorption, a critical failure mode in high-performance products.

ADL design varies by product category. Heavy-flow menstrual pads use thicker, more robust ADLs with higher SAP incorporation to handle sustained fluid delivery. Baby diapers prioritize acquisition speed over distribution because fluid comes in bolus doses rather than continuous flow. Incontinence products balance both, as they must handle variable volumes and longer wear times. Some premium products use dual-layer ADL systems or incorporate hydrophobic elements to prevent backward leakage.

The ADL emerged as a distinct component during the 1980s as diaper performance standards tightened and manufacturers sought to reduce bulky absorbent cores while improving dryness perception. It represents the boundary between consumer-facing comfort engineering (topsheet and ADL) and utilitarian absorption science (core and backsheet). Failure analysis of field complaints often traces to ADL migration, delamination from the core, or saturation of the polymer particles, which signals that the product has exceeded its designed wet capacity.