A kind of prepolymerization-emulsification fully continuous method for preparing waterborne polyurethane

Abstract

The invention discloses a process method for fully continuous preparation of water-based polyurethane by prepolymerization-emulsification. In this method, the sonochemically strengthened twin-screw extruder is used as the water-based polyurethane prepolymerization and neutralization reactor, and the static mixer and tubular emulsifier are used as the prepolymer emulsification device. The prepolymerization and emulsification are fully continuous, and the production efficiency is high. , low cost, stable product quality, especially suitable for the production of high-solid aqueous polyurethane. More importantly, in a specific area of ​​the twin-screw extruder, a special ultrasonic generator is installed to perform sonochemical treatment on the prepolymerization intermediate, which can significantly improve the reactivity of the material, so that the late stage of the prepolymerization reaction can be at 70‑80 It is completed quickly under low temperature conditions, the production process is energy-saving and environmentally friendly, and side reactions such as branching, cross-linking, and degradation caused by high temperatures in the later stage are avoided. The obtained water-based polyurethane has a controllable structure and stable quality. The above process method does not use any organic solvent, has no selectivity to raw materials, and is applicable to the synthesis of any type of water-based polyurethane.

Description

technical field [0001] The invention relates to a prepolymerization-emulsification fully continuous method for preparing water-based polyurethane, which belongs to the field of polymer materials. Background technique [0002] Waterborne polyurethane came out in the 1960s. It is a new type of polyurethane system that uses water instead of organic solvents as the dispersion medium. Compared with traditional solvent-based polyurethane, water-based polyurethane only volatilizes into the atmosphere during use, which is environmentally friendly and meets the requirements of modern green chemical processes; at the same time, because the dispersion medium is water, water-based polyurethane is also non-toxic, non-flammable, and non-toxic It can replace traditional solvent-based polyurethane and is widely used in leather, synthetic leather, biomedicine, furniture, automobiles, aerospace and other fields. It is a new material that is being developed by the country. [0003] At present...

AI Technical Summary

Problems solved by technology

This production process mainly has the following disadvantages: (1) long reaction time (6-8 hours), low production efficiency, and high production cost; (2) production is overly dependent on labor, and the degree of automation is low; (3) product quality is unstable, There is a large difference between batches; (4) In order to facilitate emulsification, a low-boiling organic solvent must be added to the prepolymer to reduce the viscosity, and after emulsification, the solvent is removed by vacuum distillation, resulting in increased energy consumption and waste of resources; Low content, resulting in high drying and shipping costs

However, the temperature of the polyurethane reaction is generally in the range of 70-90°C, especially in the late stage of the reaction. If the temperature exceeds 90°C, side reactions such as branching and cross-linking will be triggered, which will destroy the ratio of raw materials and cause the product structure to be out of control. Emulsification also affects product quality