Can polyurethane ink binders be mixed and used at will?

2026,04,10

Polyurethane ink binders must not be mixed or used randomly. Otherwise, it may cause system conflicts, performance degradation, or even product failure. It is necessary to strictly follow the three principles of the same system, the same type, and small-scale confirmation.

Why can't they be mixed randomly?

1. Conflict between structure and cross-linking: Different binders have different resin hardness, Tg, molecular weight, OH/NCO ratio, etc. Mixing them will disrupt the cross-linking density, resulting in decreased adhesion, wear resistance, and resistance to boiling, and causing stickiness, color fading, or interlayer separation.

2. Incompatibility between solvents and pigments: The solvent system (alcohol-based / solvent-based), pigment dispersion, and additives do not match, which will cause flocculation, stratification, turbidity or color change, seriously affecting film formation and coloration.

3. Mismatch between system and application: Polyurethane ink and chlorinated polypropylene (OPP) system ink cannot be miscible and can only be used in a layered manner. Gold/silver inks, due to the characteristics of the metal powder, are not suitable for boiling or high-barrier packaging and must not be mixed with ordinary color inks.

Correctly mix the three-step method

1. First, confirm the same system: It is limited to the same type (such as aliphatic PU for aliphatic PU), the same brand and series of binders. Different systems must not be mixed.

2. Control the proportion and sequence: Start with low concentration and then increase, conduct a small-scale trial mix with a small amount, prioritize mixing the resin before adding the colorant, and avoid directly pouring the high-solid content material into the thinner.

3. Must conduct small-scale test verification: Measure viscosity, fineness, adhesion, scratch resistance, and composite peel strength. Only use it in batches after it passes the test.

Author:

Ms. Cherry

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348754229@qq.com

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