Flexo Printing on Nonwoven: Color Reproduction and Design Considerations for Low-Surface-Energy Substrates
Nonwoven substrates have a rough, textured surface that scatters light and reduces color saturation compared to smooth films or papers. Additionally, the low surface energy of synthetic nonwovens (unless treated) can affect ink wetting and color intensity. This article provides guidelines for design and color management to achieve optimal visual impact on nonwovens.
Color gamut: The effective color gamut on nonwoven is smaller because the pigment particles may be partially hidden by the fiber structure, and the surface texture reduces gloss, making colors appear duller. The gamut is further reduced for low-dye-yield fibers (PP is naturally white but slightly translucent). To compensate, the ink formulation should have high pigment load and large particle size (to avoid penetration), and the film thickness should be increased (higher anilox volume). However, this may affect flexibility and rub resistance, so a balance is needed.
High Speed Flexo Printing Machine - Stack Flexo Flexo Printing Machine
Design considerations: Fine lines and small text may be lost in the fiber texture. Minimum line width should be at least 0.5 mm, and font sizes should be large (e.g., 10 pt or above). Avoid high-frequency screens (above 100 lpi); use lower screens (60-80 lpi) with larger dots that bridge the fiber gaps. Use high-contrast colors (e.g., dark on light) for legibility. Avoid subtle gradations, as they appear as bands due to the uneven surface.
Pre-treatment: Corona or flame treatment increases surface energy, improving wetting and color density. The dyne level should be at least 40 dynes/cm for good color saturation. A primer can also be used to provide a smooth layer for the ink to sit on, but this may affect the fabric's hand feel. For high-end applications, a pre-coating (e.g., acrylic) is applied to the nonwoven before printing.
Color measurement: Standard spectrophotometers with reflectance mode work on nonwoven, but the rough surface introduces measurement noise. Averaging multiple readings is recommended. The gloss component should be excluded (using SCI vs. SCE mode). The target color values should be set based on the specific nonwoven material, not on a smooth proof. A sample run with the actual material is necessary for accurate color matching.
Visual assessment: Because the substrate is porous, the printed area may have a mottled appearance. The contrast can be improved by using a white background (pre-printing white) to block the substrate color, especially for films. For nonwoven, a white layer may be too expensive; instead, choose a darker ink for better coverage. The design should use large solid areas for brand colors, as halftones appear less saturated.
Sustainability: Many nonwovens are made from recycled or biodegradable materials, which may have variable surface properties. The ink should be compatible with the material's recyclability. Water-based inks are preferred. By understanding the limitations and adapting design and process,
flexo printing on nonwoven achieves acceptable color reproduction and legibility, meeting the functional and aesthetic needs of disposable products.
