Preparation method of waterborne polyurethane free of cosolvent

Abstract

The invention relates to a preparation method of waterborne polyurethane free of a cosolvent. The method comprises the steps of blending 2,2-dimethylolpropionic acid DMPA with aliphatic diol at room temperature, heating a mixture until DMPA is completely melted under the conditions of stirring and nitrogen protection and cooling to room temperature to obtain a low-melting point chain extender; mixing the low-melting point chain extender with oligomer polyol and then carrying out decompression dehydration; adding diisocyanate, reacting at 70-90 DEG C under the condition of nitrogen protection for 1-3h to obtain a polyurethane prepolymer; cooling the polyurethane prepolymer to the room temperature, adding triethylamine to neutralize, adding deionized water, dispersing the triethylamine into the deionized water; adding ethylenediamine for chain extension to obtain the waterborne polyurethane. The method is simple; and the prepared waterborne polyurethane is safe, environment-friendly and suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of preparation of water-based polyurethane, in particular to a preparation method of water-based polyurethane without cosolvent. Background technique [0002] Water-based polyurethane is different from traditional solvent-based polyurethane. It is an environmentally friendly material that uses water instead of organic solvents as the dispersion medium. There are many types of water-based polyurethane, among which anionic water-based polyurethane is the most widely used. At present, the acetone method is generally used in the industry to prepare anionic water-based polyurethane. Among the many anionic chain extenders, dimethylolpropionic acid (DMPA) is the most widely used one, but its disadvantage lies in the high melting point of DMPA (160 ° C -170°C), the solubility in acetone is low, and it is difficult to heat and dissolve. This requires the addition of cosolvents such as N-methylpyrrolidone (NMP), dimethylformam...

AI Technical Summary

Problems solved by technology

However, dimethylolbutyric acid (DMBA) and sodium 2,4-diaminobenzenesulfonate (SDBS) are expensive and economically poor, and are difficult to be widely used in industry

In addition, there are studies using DMPA and active monomers such as: caprolactone, ethylene oxide, propylene oxide and tetrahydrofuran to lower the melting point of the chain extender, thereby further preparing water-based polyurethane without cosolvent ([4] Chen Dajun, Wu Jianru. A preparation method of chain extender for water-based polyurethane: CN103214668, 2015.), but this method has complicated process and high cost