Practical Strategies for Scaling Up EVA–PU Blends from Lab to Production

Many EVA–PU formulations perform well in the laboratory but fail during scale-up. The main reason is that laboratory conditions often mask sensitivities related to shear, addition rate, and time-dependent stability.

In small-scale tests, materials are typically added slowly and mixed uniformly. In production, however, flow patterns, local concentration gradients, and residence time vary significantly. These factors can amplify incompatibility between EVA latex and anionic PU dispersions.

 critical parameters during scale-up is addition rate. EVA latex should be introduced into PU dispersion gradually, allowing the system to equilibrate. Rapid addition can create localized ionic shock, collapsing colloidal stabilization layers.

Shear control is equally important. Excessive shear can damage particle surfaces, while insufficient shear leads to poor distribution. A staged approach—moderate shear during addition followed by gentle mixing—is often  effective.

Finally, scale-up trials must include extended storage tests. A formulation that survives only immediate processing is not production-ready. Designing EVA–PU systems with scale-up behavior in mind significantly reduces the risk of downstream failures.

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