Core Application Methods and Spray Technologies for Hygiene HMPSA

On automated production lines for disposable hygiene products (such as baby diapers and sanitary pads), Hot Melt Pressure Sensitive Adhesive (HMPSA) displays distinctly different spray patterns and application forms depending on the specific nozzles and air-flow controls used.

Below are illustrations and functional descriptions of the four core glue spraying/coating methods used in industrial manufacturing:

Pattern Characteristics & Visual Identification

1. Spiral Spray

• Visual Characteristics: Displays a continuous, uniformly overlapping pattern of loops or spiral meshes.

• Application: The most common method for structural construction bonding (e.g., laminating the nonwoven top sheet to the absorbent core and PE back sheet).

• Function: The open gaps between loops allow liquid penetration and air permeability while ensuring robust bond strength.

2. Elastic Strand Coating (Omega / V-Slot Spray)

• Visual Characteristics: The adhesive envelops the ultrafine elastic spandex strands like silk, achieving a 360-degree total encapsulation.

• Application: Securing elastic strands on baby diaper leg cuffs and waistbands.

• Function: Firmly anchors stretched elastics to prevent snap-back (creep failure), directly eliminating side leakage.

3. Fiberization / Micro-Fiber Spray

• Visual Characteristics: Denser and finer than spiral spraying, forming a random matrix similar to cotton candy or a micro-spiderweb.

• Application: Ultra-thin core laminations and premium ultra-soft nonwoven bonding.

• Function: Achieves low add-on coat weights while preserving a feather-soft hand-feel without stiffening the nonwoven fabric.

4. Slot Die Coating

• Visual Characteristics: Applied without air assistance. The molten adhesive is extruded directly through a flat slot die onto the substrate, forming a continuous, seamless film.

• Application: Feminine sanitary pad positioning back-glue (garment attachment) and frontal landing zone tapes.

• Function: Provides 100% surface coverage with high shear strength and exceptionally clean, sharp cutoff edges.

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