High Solid Content Polyurethaiie Dispersion Based On Diaminosulphonate And Aromatic Diisocyanate

High solid content polyurethane dispersions (PUDs) have advantages of highvolatilization of water and low cast of storing and transportation. Aromatic isocyanate hashigh activity, therefore it is difficult to prepare high solid content aromatic PUDs. As a result,solid content of aromatic PUDs is10-30%. Aromatic isocyanate can only be applied in lowdemanding areas because of low solid content. Due to low price, the use of aromatic isocynatecan effectively reduce production costs. Meanwhile, due to its excellent comprehensiveperformance, aromatic solvent-based polyurethane has obtained a wide range of applications.In a word, the research of high solid content aromatic PUDs has profound significance. Highsolid content aromatic PUDs had not been reported.Now，the most popular hydrophilic monomer in waterborne polyurethane industry iscarboxylic acid type. Carboxylic acid salt is a kind of weak acid mild base salt, which haspoor hydrophilic. A large amount of carboxylic acid salt is needed, which lead to poor waterresistance. So it is not suitable for preparing high solid content PUDs. In addition, the-COO group in polyurethane segment accelerates the degradation of polyurethane and reduces thelife of polyurethane materials. Moreover, amines are needed in neutralization step, which isbound to bring an unpleasant odor. So carboxylate based PUDs cannot be applied in foodpackaging. The use of sulphonate can avoid all the above problems and also be effective toimprove the solid content of aromatic PUDs.In this paper, polyurethane dispersions (PUDs) about50%solid content were synthesizedby acetone process using2,4-toluene diisocyanate(TDI) or diphenylmethane diisocyanate(MDI) as primary component in hard segment and ethylenediamine sodium sulphonate(AAS-Na) as a new type of highly versatile hydrophilic chain extender. High solid contentaromatic PUDs can be used in lower anti-yellowing requirements fields, such as adhesive,coating and leather, etc. High solid content aromatic PUDs have low production cost and abroad range of application.The results:1. PUDs based on TDI: the average particle sizes of PUDs were at60-160nm,particle size distribution (PSD) of some samples was bimodal distribution, and the value ofzeta potentials of PUDs was between-50mV and-65mV, which revealed that PUDs hadexcellent stability. Brookfield viscosity was less than200mPa·s. Transmission electronmicroscope (TEM) analysis showed PUDs particles were spherical shapes with different sizes.Dynamic mechanical thermal analysis(DMA) showed PUDs films had good compatibility ofsoft and hard segment and no phase separation. The measure of tensile tests showed that the ultimate elongation of PUDs cast films was all more than2000%and the films were soft butnot sticky.2. PUDs based on MDI: the average particle sizes of PUDs were at80-220nm. The valueof zeta potentials of PUDs was between-30mV and-40mV, which revealed that PUDs hadexcellent stability. Brookfield viscosity was between40mPa·s and240mPa·s. Dynamicmechanical thermal analysis(DMA) revealed that the films of PUD with low Tg were between-5℃and-20℃. That means PUD films have good mechanical properties at low temperatures.The films were translucent or opaque crystalline films. The measure of tensile tests showedthat the elongation at break increased and the tensile strength decreased with increasing PNA content.