Problems that need to be paid attention to when using roller-coated ink leveling agent

When using roller-coated ink leveling agent, it is necessary to comprehensively consider the addition amount control, compatibility matching, process condition adaptation, storage and safety, etc. The following are specific precautions and solutions:

1. Addition amount control

Avoid excessive addition

Adding too much leveling agent will cause the ink viscosity to be too low, resulting in sagging (ink flowing on the vertical surface), slow drying speed, reduced scratch resistance and other problems. For example, if the addition amount exceeds the recommended value (usually 0.1%-3% of the total ink), the ink may not form a uniform coating on the surface of the substrate, resulting in a rough surface of the printed product.

Solution: Use strictly according to the recommended addition amount, and determine the optimal amount through small tests.

Prevent insufficient addition

Insufficient addition will lead to poor ink leveling, orange peel texture (surface similar to orange peel unevenness), shrinkage (ink cannot be evenly spread, forming round or irregular holes) and other defects.

Solution: Gradually increase the addition amount, observe the ink fluidity and surface effect, and avoid excessive addition at one time.

2. Compatibility matching

Ink system compatibility

The leveling agent needs to be compatible with the resin and solvent in the ink, otherwise it may cause the ink to stratify, gel or abnormal viscosity. For example, if the leveling agent reacts with the organic solvent in the ink, the ink may lose fluidity.

Solution: Perform a small test before use to observe whether the ink becomes turbid, precipitated or changes in viscosity.

Additive synergy

The leveling agent may interact with other additives (such as defoamers and dispersants), resulting in functional failure. For example, some defoamers will destroy the molecular layer formed by the leveling agent and affect the leveling effect.

Solution: Give priority to leveling agents that are compatible with existing additives, or adjust the formula through experiments.

3. Process condition adaptation

Rolling speed and pressure

Excessive rolling speed or improper pressure will cause the leveling agent to not work fully. For example, if the rolling speed is too fast, the ink may not stay on the surface of the substrate for enough time, resulting in the leveling agent not being evenly distributed.

Solution: Adjust the rolling parameters according to the characteristics of the leveling agent to ensure that the ink has enough time to level.

Drying conditions

Excessive temperature and humidity will prolong the drying time and cause the leveling agent to fail. For example, some leveling agents may evaporate too quickly at high temperatures and lose their effect.

Solution: Control the drying environment, or choose a leveling agent that is resistant to temperature and humidity.

4. Storage and safety

Storage conditions

Leveling agents are easily degraded under high temperatures and light, affecting performance. For example, silicone leveling agents may lose their surface activity if exposed to ultraviolet rays for a long time.

Solution: Store in a cool, dark place and avoid contact with strong oxidants.

Operational safety

Some leveling agents contain organic solvents, which may be harmful to health if inhaled or contacted. For example, solvent-based leveling agents may contain volatile organic compounds (VOCs) such as toluene.

Solution: Wear protective gloves and masks, keep ventilation, and avoid direct skin contact.

5. Common problems and countermeasures

Ink stratification

Reason: The leveling agent is incompatible with the ink.

Solution: Replace the compatible leveling agent, or adjust the ink formula.

Surface shrinkage

Reason: The surface of the substrate is contaminated or the leveling agent is insufficient.

Solution: Clean the substrate and increase the amount of leveling agent.

Drying speed slows down

Reason: Overdosage of leveling agent.

Solution: Reduce the amount added, or increase the drying temperature.

Printed products lack gloss

Reason: Improper selection of leveling agent.

Solution: Replace with high-gloss leveling agent, or adjust the roller coating process.