Synthesis And Research Of Waterborne Polyurethanes Adhesive

Polyurethane adhesives have excellent bonding properties,but in the process of preparation and use,a large amount of volatile organic solvents are used,which is harmful to the environment and human health.With the progress of society,people’s awareness of environmental protection has increased,and the requirements for material safety have become higher and higher,so solvent-free water-based polyurethane adhesives have come into being and are widely used in industries such as shoe sole bonding,automotive interior trim bonding,apparel processing and composite film manufacturing.Water-based polyurethane adhesives have great potential for development,but thermal stability,water resistance and bond strength improvements are still needed.In this paper,a one-component waterborne polyurethane adhesive was synthesized by using poly(adipic acid-1,4-butanediol)diol(PBA)and isophorone diisocyanate(IPDI)as the main reactive monomers and chain expansion by small molecule chain extenders,and methyl methacrylate(MMA)and butyl acrylate(BA)were selected as acrylate monomers.The grafting agent,hydroxyethyl methacrylate(HEMA),was used to establish a chemical linkage between the polyurethane molecular chain and the acrylate molecular chain to obtain acrylate modified waterborne polyurethane(WPUA)adhesives.The structure of the main chain of polyurethane was controlled by adjusting the initial-NCO/-OH value and changing the type of small molecule chain extender;the connection between the molecular chain of acrylate and the molecular chain of polyurethane was controlled by changing the content of grafting agent;the structure of the molecular chain of acrylate was controlled by adjusting the ratio of acrylate content and acrylate monomer content,and the thermal stability,water resistance,adhesive strength and other properties of the adhesive were The thermal stability,water resistance,adhesive strength and other properties of the adhesives were investigated.The effect of the initial-NCO/-OH value on the performance of one-component waterborne polyurethane adhesives was investigated.It was found that with the increase of the initial-NCO/-OH value,the particle size of WPU emulsion increased,the stability decreased,the surface tension increased so that the wettability became poor,the surface free energy decreased,the hydrophobicity was enhanced,the water absorption decreased,and the adhesive strength was greatly improved.The influence of small molecule chain extender type,i.e.chain extender method,on the performance of one-component waterborne polyurethane adhesives was studied.Good water resistance.The effect of grafting agent hydroxyethyl methacrylate(HEMA)content on the performance of WPUA adhesives was investigated.With the increase of grafting agent HEMA content,the emulsion particle size decreased,the emulsion surface tension decreased and the wettability improved,and the water resistance and adhesive properties were improved.The effect of acrylate content on the performance of WPUA adhesives was investigated.With the increase of acrylate content,the particle size of WPUA emulsions became larger,the stability decreased,the surface tension decreased and the wetting ability increased,the thermal stability became better and the adhesive performance improved.The effect of acrylate monomer content on the performance of WPUA adhesives was studied,and it was found that as the MMA content decreased BA content increased,the emulsion particle size gradually decreased,surface tension decreased,wetting ability increased,the free energy of the adhesive surface increased,surface hydrophobicity became worse,bond strength decreased,and water resistance decreased.