Method for synthesizing water-dispersion organosilicon-polyurethane block copolymer

Abstract

The invention discloses a synthesis method for waterborne organocilicon-polyurethane block copolymer, comprising steps as follows: reaction is carried out between polyisocyanate and polyol (the polyol comprises the one from the castor oil and carboxyl polyol) to generate isocyanate-terminated polyurethane prepolymer; then chain extension is carried out via amino alkyl polysiloxane; eventually alkaline aqueous solution is adopted for neutralization and dispersion, to prepare aqueous dispersion with excellent dispersion and stability. In addition, the aqueous dispersion is applied as coating for the wood and paper, as finishing agent for leathers and textiles, or as adhesives. Since natural vegetable oil from castor beans is selected and amino alkyl polysiloxane is adopted as the chain extender. The synthesis method for waterborne organocilicon-polyurethane block copolymer has the advantages of remarkably improved hydrophobic property, heat resistance and surface smoothness for the polymer films, simple preparation technique, and easy operation.

Description

technical field [0001] The invention relates to a synthesis method and application of a water-dispersed organosilicon-polyurethane block copolymer Background technique [0002] One-component self-emulsifying waterborne polyurethane has the advantages of good stability of aqueous dispersion, non-toxicity, environmental friendliness, good adhesion, good wear resistance, good low temperature flexibility and high mechanical strength. However, due to the presence of self-emulsifying groups such as carboxyl, amino, and oxyethylene ether groups in the polyurethane molecular chain, its water resistance is poor. Therefore, how to improve its water resistance has become an urgent problem to be solved. The methods currently used are: one-component mainly uses blocked polyurethane to heat and deblock to free isocyanate groups and react with hydrophilic carboxyl groups, amino groups, urea groups, carbamate groups, etc., so that hydrophilic carboxyl groups, amino groups, etc. become hydr...

AI Technical Summary

Problems solved by technology

For example, the physical blending method of hydroxyl silicone oil emulsion and water-based polyurethane emulsion is used, but because of the poor compatibility of hydroxyl silicone oil and polyurethane, silicone is easy to migrate to the surface and cause phase separation, so the effect is not ideal; some chemical methods are modified. Hydroxyl-terminated polysiloxane and polyol react with isocyanate together, and some use hydroxyl-terminated siloxane as chain extender to react with isocyanate group in prepolymer

However, due to the low reactivity of silanol (HO-Si) and the poor hydrolysis resistance of the Si-O-C groups generated by the reaction, the obtained organosilicon-modified waterborne polyurethane has little effect on improving the water resistance of polyurethane films. Soaking in water quickly turns white, swells until dissolved

At the same time, the transparency of the film-forming material is not good, which affects its application range

In addition, the use of aminosilane coupling agent to modify water-based polyurethane has also been reported, but due to the small molecular weight of the silane coupling agent, the siloxane segment introduced into the molecule after chain extension is shorter and the organic silicon content is lower, which improves the polyurethane coating film. The effect of hydrophobicity is not ideal

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