Water based Polyurethane WPU

Waterborne Polyurethane, full water-borne Polyurethane (Water based Polyurethane WPU), it mainly contains hydroxyl containing alcohol and isocyanate based isocyanate by reaction generates more block Polyurethane polymer, its molecular structure contains a lot of repeated carbamate.
Research on the polymerization of waterborne polyurethane began in the 1940s, and now it has been applied in all fields of our daily life.The first aliphatic isocyanate was successfully prepared by German professor Wurtz in 1849.However, the emergence of polyurethane was not successfully synthesized by German chemist Otto Bayer through 1, 4-butanediol and hexamethylene diisocyanate until 1937.After that, polyurethane, with its excellent and unique properties, was quickly applied to many chemical industries.So later Germany is also known as the birthplace of the polyurethane industry.Then with the rapid development of the global economy, people attach great importance to the concept of environmental protection.At the same time, under the great stimulation of the industrial market, the research of waterborne polyurethane came into being in the early 1990s.After 30 years of development, Belgium united chemical enterprises co., LTD., American Air Products company, British zeneca company have carried out in-depth research on waterborne polyurethane.Compared with other countries, the research on waterborne polyurethane in China develops slowly. Starting from 1970s, polyurethane was successfully synthesized and put into industrial production for the first time in 1989.As of today, China's output of polyurethane has reached 10 million tons, accounting for about 50% of the world's total output of polyurethane

However, these new waterborne polyurethanes show great excellence in water resistance, solid content, mechanical properties and thermodynamics.
A kind of hard segment of waterborne polyurethane with sulfonic acid group in the molecular chain was synthesized, and its dispersion system had lower viscosity and higher solid content.The results show that this kind of aqueous polyurethane with sulfonic acid has better mechanical properties and storage stability than carboxylic acid type.This is because the sulfonic acid group has a large double electric layer potential, and the electrostatic repulsion between molecules prevents the condensation between molecules, which makes the synthesized waterborne polyurethane produce strong hydrophilicity and the dispersion stability is improved.At the same time, the introduction of sulfonic acid groups increases the content of hard segments in the whole system, resulting in increased intermolecular forces and more orderly arrangement of molecular structures.
Water - based polyurethane with solid content of 40 % was synthesized by sulfonic acid and hydrazine chain extender.The results show that the emulsion stability, elongation at break, tensile strength and thermodynamic stability of the film are significantly improved.
Castor oil was used as crosslinking agent to synthesize castor oil modified waterborne polyurethane.The results showed that with the increase of castor oil content, the hydrophobicity and mechanical properties of the film were improved.Thus the application range of waterborne polyurethane has been broadened.
Using rosin as modifier, polycaprolactone diol (PCL220N) and tdi-80 as main synthetic materials, the modified TDI waterborne polyurethane adhesive was successfully prepared.The results showed that the tensile strength of waterborne polyurethane film reached the maximum when the rosin was 5.73 %

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