Film-free gradient nonwoven via directional vapor deposition and plasma treatment

Overview

This innovative technology delivers a film-free gradient nonwoven that combines directional liquid resistance with breathability, addressing a key trade-off in hygiene and protective fabrics. By depositing parylene C on individual fibers rather than forming a standalone film, the process preserves the open fibrous structure while enabling precise control over pore size and surface wettability. A directional plasma treatment creates a denser, liquid-resistant region on one face while retaining an open, breathable region for water-vapor and air transport. The result is a lightweight fabric that prevents fluid penetration yet remains comfortable and soft—ideal for diapers, feminine hygiene products, medical drapes, and protective apparel.

Unlike conventional film laminates, this approach maintains the fabric's flexibility, breathability, and softness, which are critical for user comfort. The process can be retrofitted onto existing nonwoven production lines, making it a low-disruption upgrade for manufacturers seeking advanced fluid management without sacrificing mechanical performance.

Technical specifications

The core technology combines two complementary surface-engineering steps:

• Conformal vapor deposition of parylene C onto individual fibers creates a controlled coating that tunes pore size and liquid-entry resistance without blocking the web's open structure.
• Directional atmospheric-pressure plasma treatment (specifically dielectric plasma vapor, DPV) modifies surface wettability. Preliminary tests on parylene-coated cellulose show contact angle reduction from ~119° to ~82° with increasing treatment time, demonstrating tunable hydrophilicity.
• Through-thickness gradient formation is achieved by optimizing plasma power, exposure time, gas composition, and treatment geometry, allowing programmed control of liquid transport from shallow surface modification to full-depth functionalization.

Feasibility studies have already demonstrated passive directional transport of artificial sweat in a skin-associated configuration, confirming the ability to independently tune liquid entry and transport within an open porous web. The technology is compatible with lightweight hygiene-grade nonwovens (spunbond, spunlace, SMS) and is designed for continuous roll-to-roll processing, with coating add-on and treatment depth optimized to meet barrier, breathability, softness, strength, and cost metrics.

Technology readiness level

The technology is at an early stage, with experimental proof-of-concept validated in laboratory settings. Preliminary results confirm stable through-thickness gradients in porous fibrous materials without altering fabric thickness or architecture. The next phase involves transferring the validated parylene-based gradient treatment to lightweight hygiene nonwovens, optimizing process parameters to meet industry performance targets, and developing a continuous roll-to-roll manufacturing process with associated cost analysis. Current readiness corresponds to TRL 3–4, with a clear path toward pilot-scale validation and commercialization.