In the field of photocurable materials, fast curing and high crosslinking of epoxy resins are the key to improving coating performance. However, under thick film (such as a single coating exceeding 100μm) or low radiation energy conditions, traditional curing systems often face problems such as asynchronous reactions between the surface and bottom layers and insufficient curing rate. To address this challenge, PAS 12 polyol, an epoxy ring-opening reaction accelerator designed specifically for cationic curing systems, significantly improves the curing efficiency and coating uniformity under thick film conditions by optimizing reaction kinetics, becoming an innovative material that has attracted much attention in industrial applications.
1. Core characteristics and mechanism of action of PAS 12
PAS 12 is a 100% solid polyol compound. Its chemical structure is designed with hydroxyl polyol as the core. It has the characteristics of low viscosity (300 cPa·s at 25°C) and high reactivity. According to the technical parameters, its acid value is extremely low (≤1mg KOH/g), density is 0.95g/cm³, and Gardner color is only 1, which ensures high compatibility and transparency in the formulation.
As an epoxy ring-opening reaction accelerator, the core function of PAS 12 is to accelerate the ring-opening reaction of epoxy groups. In cationic curing systems, acidic substances produced by photoinitiators trigger the polymerization of epoxy resins. However, under thick film conditions, limited light penetration leads to delayed reaction of the bottom layer, which is prone to incomplete curing or delamination defects. PAS 12 forms hydrogen bond interactions with epoxy groups through its polyhydroxy structure, reducing the activation energy of the reaction, thereby accelerating the crosslinking speed in the chain growth stage. Experiments show that after adding PAS 12, the curing reaction of the coating surface and bottom layer can be highly synchronized, the crosslinking density is increased by about 30%, and the mechanical strength and chemical resistance of the thick film are significantly improved.
2. Breakthrough applications of thick film curing
1. Rapid curing of thick film coatings
In applications where the thickness of a single coating exceeds 100μm (such as electronic packaging and heavy-duty anti-corrosion coatings), the addition of PAS 12 shortens the curing time to less than 50% of the traditional system. Even with low-energy UV light sources (such as LED-395nm), the coating can still be cured synchronously inside and outside to avoid deformation or yellowing of the substrate due to heat accumulation.
2. Deep curing of complex structural parts
For workpieces with three-dimensional structures or internal cavities (such as automotive parts and optical devices), PAS 12 promotes the uniformity of epoxy ring-opening reactions to ensure that areas that are difficult for light to reach can still be fully cured. This feature is particularly suitable for areas that require strict coating integrity.
3. Performance optimization of high cross-linking system
In applications requiring high cross-linking density (such as high temperature resistant insulating paint, high hardness floor coating), PAS 12 not only improves the curing rate, but also gives the coating higher wear resistance, impact resistance and solvent resistance by strengthening the cross-linking network between molecular chains.
III. Usage recommendations and compatibility
- Addition ratio: The recommended addition amount is 0.5%-2% of the total formula, which needs to be adjusted according to the resin type and curing conditions.
- Process adaptability: PAS 12 is suitable for a variety of curing light sources such as UV-LED and mercury lamps, and has excellent synergy with common cationic photoinitiators (such as iodonium salts).
- Storage and safety: It needs to be stored in a dark environment below 25°C and avoid contact with strong oxidants.
IV. Industry application cases
1. Electronic packaging materials
In semiconductor packaging glue, the application of PAS 12 enables thick layers of epoxy resin (>200μm) to be cured within 60 seconds without bubbles or cracks, greatly improving packaging reliability.
2. Industrial anti-corrosion coatings
After adding PAS 12 to a heavy machinery coating, the curing rate increased by 40%, and the corrosion resistance time of the coating in the salt spray test was extended to more than 2,000 hours.
3. Optical adhesives
In the UV adhesive used for lens bonding, PAS 12 ensures that the adhesive layer can be uniformly cured even when the thickness is uneven, avoiding the problem of light distortion.
V. Conclusion
As a highly efficient epoxy ring-opening reaction accelerator, PAS 12 solves the technical bottleneck in thick film curing through unique chemical design and functional optimization, and provides reliable support for cationic light curing systems. Its low addition amount, high compatibility and significant performance improvement make it show broad application prospects in high-end manufacturing fields such as electronics, automobiles, and optics. In the future, as light curing technology develops towards a more efficient and environmentally friendly direction, PAS 12 may become an important boost to promote industry progress.
