company news about Combination of UV and thermal curing: A leading solution for high wear resistance and anti-yellowing of automotive interior coatings

Combination of UV and thermal curing: A leading solution for high wear resistance and anti-yellowing of automotive interior coatings

  In the automotive interior manufacturing sector, the performance of coating technology directly impacts product competitiveness. Traditional single-curing technologies (such as pure UV or pure thermal curing) are no longer able to meet the current industry's multiple requirements for environmental protection, durability, and production efficiency. While UV curing can achieve surface definition in seconds, insufficient UV penetration on dark substrates (such as composites containing carbon black) can lead to incomplete curing in shadowed areas, significantly reducing coating adhesion and abrasion resistance.

  Generally speaking, black coatings thicker than 50μm have a transmittance of less than 5% for 365nm UV light, resulting in a crosslinking degree at the bottom of the coating of only 30%-40% of the theoretical value, which can easily lead to cracking or peeling during subsequent use.On the other hand, while thermal curing technology can achieve deep curing, it requires high temperatures exceeding 150°C for dozens of minutes, which not only consumes a lot of energy but can also cause deformation of the plastic substrate. This is especially true with the trend towards lightweight new energy vehicles and the increasing use of heat-sensitive materials (such as carbon fiber composites), which has made the limitations of traditional thermal curing increasingly apparent.

  It is against this backdrop that dual-curing technology, combining UV and thermal curing, emerged. This technology leverages the synergistic effects of light and heat to precisely address two key flaws of traditional processes: first, it leverages the rapid setting capabilities of UV curing to improve production efficiency; second, it optimizes the coating structure through deep cross-linking through thermal curing, thereby achieving a balance between environmental performance, performance, and cost.

  The core of the combined UV and thermal curing technology lies in the orthogonal reaction system design of dual curing groups. B-6210 resin introduces hydroxyl-acrylate bonds, enabling free radical polymerization via a photoinitiator (such as Irgacure 184) during the UV curing stage, forming an initial three-dimensional network structure. During the subsequent thermal curing stage, the hydroxyl groups undergo cross-linking reactions with isocyanate groups, further enhancing the coating's density.

  In practical applications, dual-cure technology achieves performance optimization through a dynamically adapted process window. The AI ​​control module developed by Core Rate Intelligence can adjust UV dosage and hot air parameters in real time based on the color and thickness of the substrate: For dark ABS shells, pre-curing with 800mJ/cm² of UV energy for 3-5 seconds, followed by thermal curing at 80°C for 30 minutes, reduces the internal stress of the coating by 32%, increases the bonding strength with the substrate to 8.5MPa, and increases the yield rate from 68% for single UV curing to 98%, while reducing energy consumption by 40%. This intelligent control not only solves the "one-size-fits-all" curing defects of traditional processes, but also provides a flexible solution for personalized manufacturing.

  Coatings created using dual-cure technology have achieved breakthroughs in abrasion resistance, yellowing resistance, and weathering resistance. Allnex's dual-cure coating achieved a haze value below 0.5 in the Taber abrasion test (CS10F wheel, 500g load), demonstrating abrasion resistance more than double that of conventional coatings. In a damp-heat aging test at 85°C/85% RH, the coating showed no blistering or peeling after 1000 hours, achieving a yellowing resistance rating of 4.5 (ISO 105-A02). These performance improvements are attributed to nano-reinforcement and molecular chain alignment. For example, Dabao Paint incorporates 5% nano-Al₂O₃ into its formulation, achieving a surface hardness exceeding 6H. Simultaneously, a gradient temperature increase (50-120°C) activates the latent curing agent, allowing the cross-linking reaction to progress layer by layer from the surface to the interior of the substrate, creating comprehensive protection from the surface to the interior.