胶接木用单组分室温固化高性能乳液的合成及固化机理研究

In view of the shortages of the adhesives for glued laminated timber, a novel design idea is proposed for developing one-component, ambient-curing and high-performance emulsion, i.e., to fabricate multiple-copolymerized core/shell structure of high-performance emulsion with vinyl acetate-based copolymer as the core and styrene-based copolymer as the shell obtaining by introducing the third monomer (acrylic) into copolymerizing system based on molecular design. The effect of synthesis technologies and the compositions of the core/shell copolymer on the microstructure and properties of the emulsion will be investigated in order to clarify the design principles and synthetic mechanism of the multiple-copolymerized emulsion with core/shell structure. The special structures of latex particles are fabricated vai multiple-copolymerization in order to improve water and heat- resistances of PVAc-based copolymerizing emulsion. The curing mechanism of the novel emulsion is studied to reveal its bonding mechanism, by which lay the theoretical foundation and technical support for the development and application of one-component and high-performance emulsion as adhesives for glued laminated timber. The design idea that can be used to prepare the one-component, ambient-temperature curing and high-performance PVAc-based emulsion without obvious cost added is quite different from traditional one that has homogenous polymer in both shell and core, which gives a new approach to functionally compound and modify polymers with various properties.

针对胶接木用胶黏剂存在的问题，提出一种研发胶接木用单组分室温固化高性能乳液的设计新思想，即采用常规化工原料，通过分子设计手段分别在核壳结构中引入丙烯酸类第三单体，构建以醋酸乙烯酯基共聚物为核、苯乙烯基共聚物为壳的多元共聚核壳结构高性能乳液。研究合成工艺与核壳共聚物的组成对乳液微观结构及性能的影响，探究多元共聚核壳结构乳液的设计原理与合成机理；通过多元共聚构建特殊乳液粒子结构，提升聚醋酸乙烯酯基乳液耐水性和耐热性；通过研究新型乳液的固化反应机制，揭示单组分室温固化高性能乳液的胶接固化机理，为胶接木用单组分高性能乳液胶黏剂的开发与应用奠定理论基础并提供技术支撑。该设计思想在不大幅度增加成本的前提下可实现聚醋酸乙烯酯基乳液的单组分化、室温固化和高性能化，突破了传统核壳乳液中核、壳均为单一组分聚合物的设计思路，可为不同性质聚合物的功能性复合与高性能化开辟一条新的途径。

基于胶接木用双组份异氰酸酯胶黏剂存在的问题，本项目提出了制备胶接木用单组份室温固化高性能乳液基胶黏剂的研究目标。首先考察了苯丙核壳乳液的制备以及结构与胶接、耐水热性能之间的构效关系，有效地改善了苯丙乳液胶黏剂的耐水热性能，并为实现高性能核壳乳液胶黏剂提供了理论和实践基础。在苯丙乳液基础上，进一步探究了聚醋酸乙烯酯基正/反向核壳乳液胶黏剂的构建，即制备了具有亲水聚醋酸乙烯酯为核、疏水聚苯乙烯为壳的特殊结构形貌的乳胶粒。所制备聚醋酸乙烯酯基反向核壳复合乳液具有多种粒子形貌结构，其胶接试件耐沸水时间超过180 min。基于聚醋酸乙烯酯基反向核壳粒子形貌的衍化规律的研究，揭示了过渡层与化学接枝结构在调控具有热力学不稳定、但动力学可及的反向核壳结构化乳液制备的作用机制。通过对苯丙核壳乳液和聚醋酸乙烯酯基核壳乳液的研究，为胶接木用聚醋酸乙烯酯乳液型胶黏剂的单组份化、室温固化和高性能化开发奠定了坚实的理论基础和技术支撑。