Coating Wrinkling During Ultra-high-frequency Electromagnetic Radiation Curing

After curing, the coating has insufficient hardness, a sticky surface, poor solvent resistance, or decreased adhesion, and obvious indentations can be seen when pressed with a fingernail. Incomplete curing means that the reactive groups in the coating are not fully crosslinked into a three-dimensional network structure, and residual low-molecular-weight components cause performance to fall short of standards. Incompletely cured coatings continue to post-cure during subsequent use, and their performance changes unstably over time.

1. Comprehensive factors: excessive and unevenly distributed electron irradiation energy causes rapid volume shrinkage of the coating. 2. Comprehensive factors: Petal Effect - local curing shrinkage produces wrinkling. 3. Substrate surface condition factors: The surface tension, cleanliness, and microscopic roughness of the substrate are the basic conditions for coating adhesion and leveling. When the substrate surface tension is lower than the coating fluid surface tension, wetting is insufficient and cratering occurs; surface contamination causes local adhesion failure; this is the primary direction for troubleshooting coating defects.

1. Process parameter optimization and adjustment: Reduce the electron beam dose or divide irradiation into multiple sessions to uniformize energy absorption. 2. Systematic troubleshooting method: Troubleshooting of coating problems follows the order of "substrate → coating fluid → coating head → curing → environment". First check the substrate surface tension (corona treatment effect) and cleanliness, then verify the coating fluid viscosity, solid content, and degassing status, then check the coating head gap and cleanliness, further verify the curing temperature and time, and finally evaluate the influence of ambient temperature, humidity, and cleanliness. 3. Preventive management: Establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or 5Why analysis to trace the root cause, and solidify countermeasures as PFMEA control points. Establish a regular equipment maintenance system and implement life management for key tooling such as dies/spinnerets/calender rolls/coating heads.

The essence of incomplete curing is that the crosslinking reaction has not reached the designed conversion rate. The core of the solution is the precise matching of the three elements of "temperature + time + formulation": ensure that the curing temperature and time are within the recommended window of the coating fluid system, verify the curing agent ratio and validity period, and for UV curing, regularly test the lamp light intensity and replace it in time.