支化聚丙烯酸酯的合成及压敏胶应用初探

Synthesis of branched polyacrylate and application of pressure sensitive adhesive

以己二醇二丙烯酸酯(HDDA)为支化单体,正十二硫醇(DDT)为链转移剂,采用自由基调聚-多烯单体共聚法(Strathclyde方法),通过自由基溶液聚合,在丙烯酸丁酯(BA)、HDDA和DDT的物质的量比为100∶10∶7.0时实现支化聚丙烯酸丁酯(BPBA)的制备。讨论了引发剂、理论固含率以及支化单体等因素对聚合反应的影响,并分析支化的形成过程,对比线性与支化聚合物的不同性质。在制备BPBA的基础上,对以丙烯酸丁酯为主单体的压敏胶制备进行初步探索。制备了不同支化程度的支化丙烯酸酯压敏胶(BPSA),并对BPSA的力学性能进行分析。研究结果表明:(1)在相同的链转移剂与支化单体比例下,聚合物的支化程度随着支化单体浓度的增多而升高;随着反应的进行,聚合物的支化程度逐渐升高,最后反应产物中由不同分子量和不同支化程度的聚合物组成。(2)相比于线性聚合物,支化聚丙烯酸酯在高含量下拥有更低的黏度以及更紧凑的分子链结构,结构与组成上的不同使得BPBA聚合物具有玻璃化转变温度低、高弹态区域不明显等特性。(3)支化丙烯酸酯压敏胶中低分子量聚合物以及支化结构的存在使得BPSA随着支化单体浓度的增大,初粘强度以及剥离强度逐渐下降。(4)外交联剂乙酰丙酮铝(ALAA)与HDDA单体都可使聚合物分子链之间发生偶联,但ALAA使得聚合物中形成体型交联结构,而以HDDA为支化单体所制备的压敏胶具有良好的有机溶剂溶解性,聚合物的可加工性较强,同时具有较高的初粘强度。

Using hexanediol diacrylate(HDDA)as the branched monomer and n-dodecanethiol(DDT)as the chain transfer agent,the branched poly(butyl acrylate)(BPBA)was prepared by free radical solution polymerization using free radical modulation-polyene monomer copolymerization method(Strathclyde method)at the mass ratio of 100:10:7.0 of butyl acrylate(BA),HDDA and DDT.The effects of initiator,theoretical solid content and branched monomers on the polymerization reaction were discussed,the formation process of branching was also analyzed,and the different properties of linear and branched polymers were compared.Based on the preparation of BPBA,a preliminary investigation was conducted on the preparation of pressure sensitive adhesives with butyl acrylate as the main monomer.The branched acrylate pressure sensitive adhesives(BPSA)with different degrees of branching were prepared,and the mechanical properties of BPSA were analyzed.The research results showed that,(1)under the same ratio of chain transfer agents to branched monomers,the degree of polymer branching increased with the increase of branched monomer concentration.As the reaction progressed,the degree of polymer branching gradually increased,and the final reaction product consisted of polymers with different molecular weights and degrees of branching.(2)Compared to linear polymers,branched polyacrylate had lower viscosity and more compact molecular chain structure at high content.The differences in structure and composition made BPBA polymers have characteristics such as low glass transition temperature and unclear high elastic state regions.(3)The presence of low molecular weight polymers and branched structures in branched acrylic pressure sensitive adhesives resulted in a gradual decrease in the tack strength and peel strength of BPSA as the concentration of branched monomers increased.(4)Both crosslinking agent aluminum acetylacetone(ALAA)and HDDA monomers could cause coupling between polymer molecular chains,but ALAA caused the formation of a three-dimensional cross-linked structure in the polymer.The pressure sensitive adhesive prepared with HDDA as a branched monomer had good organic solvent solubility,strong processability,and high tack strength.