Preparation method of aqueous polyurethane emulsion with high solid content

Abstract

The invention relates to a preparation method of an aqueous polyurethane emulsion with a high solid content. The method comprises the following steps: first, adding polymer polyol, polyisocyanates, catalyst and chain extender into a reactor according to certain steps, and controlling hydrophilic groups to distribute on molecular chain ends; then adding polyisocyanates to form a performed polymer terminated with an NCO group; then reducing system temperature, adding a neutralizer for neutralization, adding deionized water, and stirring with high speed to carry out water dispersion; at last, adding a post chain extender to carry out chain extension in water; removing the solvents under a reduced pressure after reaction to obtain the aqueous polyurethane emulsion. According to the invention, hydrophilic efficiency of the hydrophilic groups is raised to lower intake amount of hydrophilic groups, and a small amount of solvents are added in the reaction to lower a system viscosity. The aqueous polyurethane emulsion prepared by the invention has characteristics of high solid content, low viscosity, good water resistance and stabile storage, and can be used in industries of paint, adhesive, leather finishing and fabric arrangement, etc.

Description

technical field [0001] The invention relates to a preparation method of water-based polyurethane, in particular to a preparation method of high-solid content water-based polyurethane emulsion. Background technique [0002] Solvent-based polyurethane products are widely used in coatings, adhesives and other fields due to their superior performance. However, a large amount of volatile organic compounds (VOC) will volatilize into the atmosphere during the film forming process, causing environmental pollution. Therefore, the development of environmentally friendly polyurethane products has attracted increasing attention. Water-based polyurethane emulsion uses water instead of traditional organic solvents as the dispersion medium of the system. It not only has the excellent properties of solvent-based polyurethane such as low temperature resistance, good flexibility, and high bonding strength, but also can significantly reduce or even completely eliminate VOC pollution to the env...

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Problems solved by technology

[0005] In addition, some water-based polyurethane products use a large amount of high-boiling and expensive solvents in the preparation process, such as nitrogen methyl pyrrolidone (Nanda A K, Wicks D A, Madbouly S A, et al. J Appl Polym Sci, 2005, 98(6 ): 2514-2520), although the introduction of this kind of solvent makes the preparation process relatively environmentally friendly and there is almost no odor during the film forming process; however, due to its high boiling point, the volatilization rate is very slow during the film forming process, especially in the In terms of decoration, it is often more harmful to the health of users than those organic solvents with low boiling points and strong odors.