Study On Synthesis And Properties Of High Solid Content Polyurethane Dispersions Based On Amino-sulphonate

Now,the most popular hydrophilic monomer in waterborne polyurethane industry is carboxylic acid type, such as 2,2-dimethylol propionic acid (DMPA). Carboxylic acid salt is a weak acid mild base salt. The hydrophilic of it is less. So it is not suitable for making high solid content polyurethane. In addition, the -COO? group in polyurethane segement accelerated the degradation of polyurethane, reduce the life of polyurethane materials. The hydrophilic group of amino-sulphonate is the sulfonate. The hydrophilic of sulfonate is stronger than carboxylic. So in fairly hydrophilic level, the molar ratio of sulfonate is less than carboxylic one. The reduction of ion in the polyurethane chain reduced electrostatic repulsion. It is more suitable for the preparation of high solid content waterborne polyurethane. In this paper, the stable polyurethane dispersions with the solid content about 50% was synthesized from N-(2-aminoethyl)-2-aminoethane sulphonic sodium(AAS-Na) as the hydrophilic monomer, different types of polyols as soft segments, mixing isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) as hard segment, and ethylene diamine(EDA) as chain extender by acetone process.In this paper, the effect of different molecule structure on the PUD properties were invesgated by rotary viscosimeter, dynamic light scattering and transmission electron microscope. The results showed that the particle size decreased but the zeta-potential and viscosity of the dispersion increased with increasing hydrophilic group content. The particle size increased but the viscosity of the dispersion decreased with increasing -NCO/-OH value. The particle size first increased then decreased with increasing chain extension degree, but the viscosity first decreased then increased. When hydrophilic groups in the polyurethane molecule was unevenly, a bimodal size distribution will be produced. Transmission electron microscopy characterization showed that the particles in the PUD were spherical structure, the small particles were placed in the gap of large ones. The viscometer characterization showed that the viscosity of samples decreased with increasing shear rate. All of the samples were pseudoplastic fluid.The effect of different molecule structure on the PUD film properties were invesgated by infrared, thermal gravimetric analysis, differential scanning calorimetry and so on. IR analysis showed that the PUD with sulfonate structure was synthesized, and the hydrogen bonds behavior was apparented between the polyurethane molecular chains. Mechanical property testing showed that the maximum tensile strength of the PUD films increased but the elongation at break decreased with increasing -NCO/-OH vaule. Crystalline polyurethane film had the biggest tensile strength and the smallest elongation at break. The water absorption of PUD film was mostly less than 10%. The water absorption of film increased with increasing hydrophilic group content and -NCO/-OH vaule. The water absorption of polyether polyurethane films was greater than the polyester ones. The thermal gravimetric analysis showed that the degradation of PUD film started at about 270℃, completed at about 500℃. The thermal stability of film decreased with increasing -NCO/-OH value. The thermal stability of polyether polyurethane films was slight worse than polyether ones. The differential scanning calorimetry DSC showed that the crystallization behavior of PUD cast films was influenced greatly by the regularity of soft segments. The dynamic mechanical analysis showed that the Tg of PUD cast film was increased with the increase of NCO/OH value.