Synthesis And Properties Of Acrylate Emulsion Pressure Sensitive Adhesive For Protective Film

In this thesis, acrylate emulsion pressure-sensitive adhesive (PSA) for protective film had been synthesized by pre-emulsifier polymerization technology, with acrylate monomers and initiator (ammonium presulfate, APS). Several variables were investigated on the properties (including physical properties of emulsion, tack, holding power, 180°peeling strength, waterproof, weatherability etc.) of PSA, they were: glass transition temperature, carboxyl monomer type and their content, initiator content, emulsifier type and their content, functional monomer type and their content and polymerization temperature. The relationships between the thickness of PSA and the properties of tack, holding power, 180°peeling strength and weatherability were discussed. The influences of peeling time and peeling speed on 180°peeling strength had also been discussed in this paper.Optimum formula for PSA was got with 70%(wt%) 2-methylhexyl acrylate as well as 25%(wt%) methyl methacrylate, 1.5-2%(wt%) methylacrylic acid,0.08%(wt%) initiator, 4%(wt%) acrylamide and 3%(wt%) emulsifier (OP-10/AES/SDS =1:3:0.5) with 75-80℃polymerization temperature. The properties of PSA synthesized under the optimum formula were as follows: tack was 7 to 9(steel-ball number), holding power was over 240 hours, 180°peeling strength was 5.85 N/25mm and peeling strength was 8.12N/25mm after three months. The weatherability of the optimum formula was good.The results indicated that the properties of PSA were influenced greatly by the thickness of PSA. The properties of PSA changed a lot with the thickness of PSA increasing from 18.2μm to 32.5μm. The changes were as follows: the tack amplified from 3 to 10(steel-ball number), holding power amplified firstly and gradually dropped, the maximum holding power was over 240 hours, 180°peeling strength sharply amplified at the initiate stage and got a platform as the thickness reached to 28μm; the weatherability was not influenced by PSA thickness. Optimum thickness was proved to be 25-28μm. Peeling strength was strengthened by time. The peeling strength amplified during the first three weeks from 6N/25mm to 7.5N/25mm, and then reached a platform. The peeling strength increased with peeling speed, there were two platforms when peeling speed were 100mm/min to 200mm/min and 250mm/min to 300mm/min.