In the fields of electronic manufacturing, automotive assembly and medical devices, reusability is becoming a core requirement for adhesive technology. Traditional adhesives are difficult to peel off once cured, which not only makes repairs difficult, but also causes waste of resources. Reusable UV film resins achieve intelligent regulation of the bonding interface through light-responsive chemical structures - under specific wavelengths of light, its peel strength can drop sharply to nearly 0 N/in, achieving non-destructive disassembly; and secondary light or heat treatment can restore viscosity. This feature allows temporary fixation and permanent bonding to coexist on the same material, greatly reducing production losses and costs.
Technology core: the secret of light-controlled reversible bonding
The core of reusable UV film resin lies in the photosensitive groups (such as o-nitrobenzyl ester and epoxy groups) in the molecular design. Taking o-nitrobenzyl ester as an example, it undergoes photolysis reaction under 240-350 nm ultraviolet light irradiation, and the molecular chain breaks, resulting in a decrease in crosslinking density and a significant decrease in peel strength. Suzhou Shihua New Materials' patented technology confirms that after UV irradiation, the photosensitive crosslinker breaks to expose the active groups in the masterbatch, and the adhesion interface is dynamically adjusted to achieve the intelligent effect of "low initial adhesion and enhanced later".
The realization of secondary bonding depends on the thermally reversible groups (such as Diels-Alder adducts) or residual active monomers in the material. When the disassembled film is heated or exposed to light of a specific wavelength, the broken molecular chains react again, the crosslinking network is partially rebuilt, and the viscosity recovery rate reaches more than 80%. This dynamic chemical balance allows a single film to be recycled 3-5 times while maintaining a peel strength of >1.2 N/mm.
Multi-field applications: from precision electronics to sustainable packaging
1. Electronic device assembly and rework
During the transfer process of Micro-LED chips, UV film resin provides an initial peel strength of 7.19-10.39 N/in to ensure precise positioning. If rework is required, the bonding force returns to zero after irradiation with an excimer laser (100 mJ/cm²), and the chip can be removed without damage. Henkel's LOCTITE DURO-TAK 3706 series solvent-based acrylic pressure-sensitive adhesive is a representative of this type. Its high light transmittance and weather resistance ensure the stability of outdoor displays.
2. Medical and optical devices
Carboxyl polyacrylate/epoxy-functionalized silica (E-SiO₂) nanocomposite coating combines anti-biofouling and anti-fogging properties. Experiments show that the anti-fogging property remains unchanged after 60 days of water immersion, and the protein adsorption fluorescence intensity is reduced by 99%, which is suitable for devices such as endoscope lenses. Its hardness reaches 1H pencil level, abrasion resistance >1300 rpm, and can withstand extreme environments from -20°C to 60°C.
3. Sustainable packaging solutions
UV-cured hot melt pressure-sensitive adhesives are gradually replacing solvent-based products. The practical cases of Hongdetang Group show that its UV tape has moderate peeling strength, no residual adhesive and no skin irritation when removed. The 100% solid content feature eliminates VOC emissions and complies with EU REACH regulations.
Future direction: Co-evolution of environmental protection and high performance
Frontier research is making breakthroughs in three aspects:
Water-based UV resin: The water-based polyurethane/silicon dioxide composite emulsion developed by Lanzhou University integrates organic-inorganic hybrid technology into the photocuring system, achieving a 200% increase in water resistance at 10% nano-SiO₂ content
Dual-curing system: Combining UV curing and moisture curing to solve the bonding problem in shadow areas, such as Wuxi Shisheng Polymer Technology Co., Ltd.'s UV-moisture dual-curing sealant has been used for 5G module packaging
Bio-based raw materials: The antibacterial properties of PLA plant fiber composite wires (such as PLA-Guard) provide new possibilities for medical adhesive films
Conclusion: A new paradigm for green bonding
Reusable UV film resin is reshaping the manufacturing process: its light-controlled reversible properties reduce more than 50% of adhesive waste; water-based and solvent-free formulas (such as UV hot melt pressure-sensitive adhesives) completely eliminate VOCs emissions; and the recycling cycle directly echoes the "dual carbon" goal. As innovative products such as U-Sunny T-7133 mature, this technology will penetrate from electronics manufacturing to the construction and energy fields, promoting the global popularization of the green bonding paradigm