In the modern coatings, inks and adhesives industries, Thick Film Curing Acceleration is a core technology to improve production efficiency and product quality. With the increasing demand for coating thickness in the industrial field (such as electronic component packaging, automotive chassis protection, etc.), how to achieve uniform curing of thick films and avoid cracking, delamination and other problems has become a challenge that the industry needs to solve urgently. This article will explore the technical difficulties and solutions in depth, and focus on the innovative value of U-Sunny PAS-12 photosensitizer in thick film applications.
Technical difficulties in thick film curing
During the curing process of thick films (usually referring to coatings with a single layer thickness of more than 50μm), photoinitiator efficiency, oxygen inhibition effect and thermal stress accumulation are the three core challenges:
Light penetration limitation: UV light or electron beams are significantly attenuated in thick films, and insufficient curing of the bottom layer will lead to decreased adhesion. Studies have shown that colored inks with a film thickness of more than 15μm may have a "dry on the surface but not dry inside" phenomenon due to insufficient free radicals in the bottom layer.
Oxygen inhibition effect: Surface oxygen combines with free radicals to form peroxides, which inhibit crosslinking reactions, especially in acrylate systems. Traditional solutions require increasing the concentration of photoinitiators or using nitrogen protection, but may introduce VOCs residues.
Thermal stress and shrinkage: When thick films are cured, the internal temperature gradient and chemical shrinkage differences are prone to cause cracks. For example, epoxy resins need to precisely control the curing rate when thickly coated (>1mm) to reduce residual stress.
Key technologies for accelerated curing of thick films
1. Optimization of photoinitiators and sensitizers
The selection of photoinitiators needs to balance light absorption efficiency and penetration depth. For example, U-Sunny's PAS-12 photosensitizer improves the utilization rate of photons through synergistic effects, and can still achieve efficient cross-linking of the bottom layer even in UV varnish with a film thickness of 100μm (35% shorter curing time than traditional products). Its unique molecular structure can reduce oxygen inhibition dependence and reduce VOCs emissions, making it suitable for environmentally friendly scenarios such as food packaging inks.
2. Process innovation: gradient curing and intelligent control
The curing curve is optimized using artificial intelligence algorithms, and the temperature and irradiation intensity can be dynamically adjusted. Studies have shown that the neural fuzzy control system can reduce the curing time of thick-layer composite materials by 35% while suppressing temperature overshoot. In addition, the online irradiation technology of the Electron Curtain Accelerator can achieve high-speed continuous production, which is particularly suitable for the industrial application of thick film solder mask layers on printed circuit boards (PCBs).
3. Material modification: cross-linking density regulation
By introducing flexible segments (such as polyurethane acrylate) and compounding with rigid monomers, the hardness and toughness of the coating can be balanced. For example, the NUVPUV series of coatings can increase the one-time spraying thickness to more than 40μm by adjusting the functional distribution, and the re-coating adhesion is increased by 20%.
U-Sunny PAS-12 industry application cases
As a high-performance photosensitizer, PAS-12 has demonstrated excellent performance in the following fields:
Coating industry: In the UV varnish for electric vehicles, PAS-12 significantly reduces the risk of thick film cracking, improves the cold and hot cycle resistance by 15%, and is suitable for extreme environments from -30℃ to 80℃.
Ink printing: With the nitrogen protection system, PAS-12 increases the curing speed of gravure printing ink at a film thickness of 50μm by 40%, and there is no solvent residue.
Adhesive field: When used in one-component epoxy adhesive, PAS-12 catalyzes the latent curing reaction, shortening the complete curing time of a 1cm thick adhesive layer from 72 hours to 24 hours.
Conclusion
Breakthroughs in thick film curing acceleration technology not only rely on innovations in material chemistry, but also require coordinated upgrades in processes and equipment. U-Sunny PAS-12 provides cost-effective solutions for the coatings, inks and adhesives industries by enhancing photoinitiator efficiency and oxygen resistance. In the future, with the deep integration of radiation curing technology and intelligent control systems, thick film applications will continue to evolve towards a more efficient and environmentally friendly direction.