Urethane Acrylate Crystallinity Reduction via Alkylene Oxide Modification

The patent changes the molecular structure parameters of the polyfunctional alcohol component by selecting specific compounds (glycerin, diglycerin, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, tris(2-hydroxyethyl) isocyanurate, or sorbitol) with controlled hydroxyl group configurations. This structural parameter adjustment reduces crystallinity and viscosity while maintaining the high crosslinking density needed for hardness, thereby resolving the contradiction between strength and handleability

The patent creates a composite reactive composition by combining urethane acrylate (derived from polyfunctional alcohol with hydroxyl groups) with additional polyfunctional (meth)acrylate compounds. This composite approach allows the system to achieve both high cured product hardness through crosslinking and acceptable handleability through the synergistic interaction of different molecular structures with complementary properties

The patent adjusts the molecular weight and hydroxyl group density parameters of the polyfunctional alcohol component. By selecting alcohols with specific structures (e.g., sorbitol with six hydroxyl groups vs. glycerin with three), the patent optimizes the balance between crosslinking density (for scratch resistance) and molecular flexibility (to reduce curing shrinkage). This parameter optimization allows the cured product to maintain adhesiveness while achieving high durability

The patent introduces local structural variations in the urethane acrylate molecule by using polyfunctional alcohols with different hydroxyl group distributions. Some hydroxyl groups form urethane linkages providing crosslinking for scratch resistance, while remaining hydroxyl groups or flexible spacer structures reduce overall molecular rigidity, thereby minimizing curing shrinkage and preventing adhesiveness reduction

The patent uses polyfunctional alcohols with multiple hydroxyl groups as intermediary structures. These molecules serve as multi-functional building blocks that provide both flow control (through molecular weight and structure optimization) and crosslinking capability (through multiple reactive sites). This intermediary approach eliminates the need for monofunctional diluents while maintaining physical properties, as the polyfunctional structure inherently provides both viscosity modification and curing reactivity

The patent designs the polyfunctional alcohol component to perform multiple functions simultaneously: it acts as a chain extender for molecular weight build, a crosslinking agent for hardness development, and a viscosity modifier through its structural properties. This multi-functionality consolidates several roles previously requiring separate additives (including monofunctional diluents) into a single component, thereby improving handleability without sacrificing cured product properties