Rheology effect of various thickeners on the adhesion property of water-based acrylic PSA

• Main Authors: Fei-Ting Cheng, 鄭妃婷
• Other Authors: 芮祥鵬
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/t82sh6

碩士 === 國立臺北科技大學 === 有機高分子研究所 === 101 === Acrylic copolymer latexes were prepared by emulsion polymerization process using anionic surfactant and nonionic surfactant as the emulsifier, respectively, and potassium persulfate (KPS) as the initiator at 78℃. The co-monomers used were 2-ethylhexyl acrylate (2-EHA), methyl methacrylate (MMA), vinyl acetate (VAc), acrylic acid (AA) and methacrylic acid (MAA). The latex was converted to pressure-sensitive adhesive (PSAs) then. Acrylic acid (AA) and methacrylic acid (MAA) to control the carboxylic acid content in the formula. Explore the carboxylic acid content on the particle size, viscosity, initial adhesion, adhesion, cohesion and the impact of the dynamic viscoelastic properties. To adjust the rheology of waterborne pressure-sensitive adhesives, different amounts of a alkali swellable acrylic emulsions (HASE) and hydrophobically modified ethoxylated polyurethane thickener (HEUR) were added. The thickened adhesive solutions were characterized by flow rheology, viscosity and the effect of changes in pH. After polymerization of the waterborne pressure-sensitive adhesives, we found that along with the increase of carboxylic acid content, the particle size decreases, the viscosity is slightly increased. By dynamic mechanical analyzer (DMA) analysis, we found that AA and MAA increases, the Tg of the Pressure Sensitive Adhesive gradually increased, cohesion has also increased, leading to the initial adhesion and peel strength decreasing. For HASE thickener, the viscosity of the waterborne pressure-sensitive adhesives increased, showing shear thinning behavior, which can be ascribed to the existence of interactions between the water-based pressure-sensitive adhesives and the thickener. From the experiments it was observed that the adhesive of carboxylic acid content increased, HASE thickening effect is affected, the viscosity rise significantly slower. Also found that the pH value of the adhesive change, HASE thickened viscosity have a dramatic impact, significantly reduced. Furthermore, water-based adhesives add HEUR thickeners to increase the viscosity. However, the carboxylic acid content of the adhesive increases, the rheological properties from Newtonian behavior gradually became the shear thinning behavior. The decrease in pH of viscose, the solution of the HEUR thickener is not.