Waterborne UV Ink for Synthetic Leather Printing

Digital printing can shorten development cycles and reduce screen-making requirements, but synthetic leather presents a difficult surface. Unlike absorbent fabric, PU and PVC skins are relatively closed, flexible and often treated with low-surface-energy finishes. The ink must wet the surface, cure quickly and remain attached through flexing, rubbing, heat and later finishing.

A 2026 study on waterborne, bio-based UV-curable acrylic-polyurethane/carbon-black ink provides a useful starting point.

What the research showed

The researchers developed a silicone-modified acrylic-polyurethane emulsion containing palm-oil-derived diethanolamide segments and hydroxyl-terminated PDMS, then blended it with a carbon-black dispersion for inkjet printing on polyester/cotton fabric.

Introducing the palm-oil-derived segment increased film tensile strength from 12.6 to 28.1 MPa. On the printed fabric, dry and wet rubbing fastness were reported at grades 3–4 and 4, while washing fastness reached grade 4–5. Relative to the original fabric, stiffness increased 28%, while air permeability retained 75.25%.

The research is published in Colloid and Polymer Science.

Why the chemistry is relevant

The palm-oil-derived segment contributes strength and renewable content, while PDMS can increase flexibility, hydrophobicity and microphase separation. UV curing offers rapid network formation and may reduce thermal exposure compared with a long oven cure.

For synthetic leather, potential uses include:

• black and dark digital printing on microfiber surfaces;
• short-run graphics on PU leather;
• variable-data or customized shoe-upper printing;
• thin decorative layers below a protective clear coat; and
• rapid sampling before rotary or screen-print scale-up.

Why textile results cannot be copied directly

Polyester/cotton absorbs liquid into its fibre structure. A compact PU or PVC surface relies much more heavily on interfacial wetting and chemical adhesion. The same ink can bead, shrink, scratch or release from a synthetic-leather surface.

PDMS creates another trade-off. It can improve flexibility and water resistance but may reduce adhesion of a later clear coat, transfer film, hot-melt layer or repair coating. The reported 28% stiffness increase may also be unacceptable for soft footwear and upholstery.

Production questions to answer

Before selecting a formulation, verify:

• particle size and filtration relative to the printhead;
• viscosity and surface tension at operating temperature;
• wetting on the exact PU, microfiber or PVC surface;
• UV dose, lamp spectrum and oxygen inhibition;
• pigment stability during storage and recirculation;
• curing at the required line speed;
• odour, residual monomer and customer RSL; and
• compatibility with the final clear coat or lamination process.

Recommended substrate and cure matrix

Keep carbon black, wetting package and total solids constant. Replace the current binder with the candidate emulsion at 0%, 25%, 50% and 100% of binder solids.

Print on three controlled substrates:

1. unfinished microfiber backing;
2. a standard WPU surface; and
3. a plasticized PVC surface.

For each formulation, test the standard UV dose and ±20% energy. Evaluate contact angle, print definition, cross-cut/tape adhesion, dry and wet rubbing, Taber abrasion, 100,000 flex cycles where appropriate, hydrolysis, cleaner resistance, heat transfer, recoat adhesion and colour migration.

The formulation should be rejected if higher colourfastness is achieved by making the product noticeably harder or by preventing later top-coating and bonding.

Application guidance

Footwear needs flexing, sweat and repeated wet-rub performance. Bags require scratch, logo adhesion and hot-press compatibility. Furniture requires cleaner, abrasion, body-oil and hydrolysis testing. Automotive printing adds fogging, odour, VOC and long heat/light ageing.

Final assessment

Waterborne UV-curable PU-acrylic ink can combine fast curing, good colourfastness and lower solvent use, but the synthetic-leather interface is the decisive factor. A successful textile ink is only a candidate. It becomes a synthetic-leather ink after it passes adhesion, flexing, recoat and ageing tests on the real product construction.