Preparation Of Water-based PU/PA、PUA Thermal Transfer Adhesive And Applied Research

The traditional hot-melt adhesive needs to be coated under heating conditions.Because of the high temperature,it is not suitable for the bonding of heat-sensitive substrates.Conversely,water-based thermal transfer adhesive that with the advantages of thin thickness,simple construction,and short heating time is suitable for thermal transfer to fabric.Waterborne polyurethane(WPU)adhesive has the advantages of environmental friendliness,cold resistance,flame resistance,and no toxicity,but their water resistance and flexibility are inferior.In this experiment,waterborne PU/PA blended emulsion adhesives and core-shell structured waterborne urethane acrylate(PUA)adhesives were prepared by compounding polyurethane(PU)with acrylic acid(PA).It not only has the properties of polyurethane but also has the water resistance and flexibility of acrylic.The thermal transfer glue prepared by the adhesive can be quickly thermally transferred onto the fabric.In this dissertation,we first studied the use of dihydromethyl propionic acid(DMPA)as a chain extender and triethylamine as a neutralizing agent to synthesize a stable waterborne polyurethane(WPU)emulsion with deionized water as dispersant under certain conditions.The influence of the isocyanate index(R value),the proportion of DMPA,and the degree of neutralization on the properties of the emulsion was investigated.Experiments found that when R was 1.3,DMPA mass was 5%,and system neutrality was 95%,a stable waterborne PU emulsion could be obtained,and the emulsion properties and mechanical properties of the film were better.In this dissertation,the core-shell structure of waterborne PUA with PA as core and PU as shell was synthesized by seed-emulsion polymerization.Experiments showed that when the R value was 1.6,the DMPA content was about 5%,the PA content was 30%,and the ratio of MMA/BA(methyl methacrylate/butyl acrylate)in the PA monomer was 60:40,the waterborne PUA emulsion with better performance was obtained.The TEM test showed that the waterborne PUA emulsion had a core-shell structure.In this paper,the excellent thermal transfer adhesive was prepared on the condition that the ratio of waterborne PA to waterborne PU/PA blend system was 40%,the Tg of aqueous PA was-20°C,the tackifier was 4% baked at 70-80°C for 30 minutes,the film surface was coated with a layer of polyamide,and hot pressing 30 s.The thermal transfer adhesive was prepared by adding 4% tackifier to the synthesized waterborne PUA emulsion and market product of U42(WPU),baking at 70-80°C for 30 minutes,and hot pressing for 30 seconds.Our results detected that the comprehensive performance of the blending aqueous PU/PA thermal transfer adhesive was better the single component waterborne PUA,the single component waterborne PUA was better than blending aqueous PU/PA adhesives through the comparison of the water-resistance,adhesion,whiteness,softness and formaldehyde content among the three kind of thermal transfer adhesives.In addition,the product’s thermal transfer process was simple,the product formaldehyde content was extremely low and environment friendly,thus,it has a potential of some practical market applications.