Method for fully continuously preparing waterborne polyurethane through prepolymerization-emulsification

Abstract

The invention discloses a process method for fully continuously preparing waterborne polyurethane through prepolymerization-emulsification. According to the method, a sonochemical enhanced double-screw extruder is used as a waterborne polyurethane prepolymerization and neutralization reactor, a static mixer and a tubular emulsifier are used as a prepolymer emulsification device, prepolymerization and emulsification are carried out continuously, the production efficiency is high, the cost is low, the product quality is stable, and the method is particularly suitable for producing high-solid-content waterborne polyurethane. More importantly, a special ultrasonic generator is additionally arranged in a specific area of the double-screw extruder to carry out sonochemical treatment on a prepolymerization intermediate, so that the reaction activity of materials can be remarkably improved, the prepolymerization reaction can be quickly completed at the low temperature of 70-80 DEG C in the later stage, the production process is energy-saving and environment-friendly, side reactions such as branching, crosslinking and degradation caused by high temperature in the later stage are avoided, and the obtained waterborne polyurethane is controllable in structure and stable in quality. The process method does not use any organic solvent, has no selectivity to raw materials, and is suitable for synthesis of any type of waterborne 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