Thiourethane Urea Resin Transparency via Segmented Polymerization

The patent divides the one-step reaction into two distinct steps: first forming the prepolymer solution by reacting amine with isocyanate, then separately adding polythiol to the prepolymer solution. This segmentation prevents premature precipitation by controlling the reaction sequence, allowing uniform mixing and proper reaction conditions to be maintained throughout the process.

The patent performs preliminary action by first preparing the prepolymer solution through reaction of amine and isocyanate before introducing the polythiol compound. This preliminary step ensures that the prepolymer is fully formed and dissolved in the appropriate solvent before the final crosslinking reaction occurs, preventing precipitation issues.

The patent introduces an intermediary substance (polythiol compound) that reacts with the prepolymer formed from amine and isocyanate. This intermediary step creates a crosslinked structure that enhances impact resistance while the controlled addition timing prevents precipitation, allowing both mechanical strength and transparency to be achieved.

The patent changes the reaction parameters by controlling the sequence and timing of reagent addition. By first forming the prepolymer solution under controlled conditions and then adding the polythiol, the reaction parameters are optimized to prevent precipitation while maintaining high reactivity for impact resistance.