Semi-rigid melamine foam plastic and preparation method thereof

A method for preparing a semi-rigid melamine foam plastic product, comprising:

• step (1):
• feeding paraformaldehyde into a reactor, adding a formaldehyde solution and polyvinyl alcohol (PVA), heating the reactor until solid particles in the reactor are completely dissolved, and then adding alkali to adjust the pH value in the reactor to be 8.0 to 9, wherein the solid particles are paraformaldehyde and polyvinyl alcohol;
• step (2):
• synthesizing a modified resin:
• feeding solid melamine powder and a modifier 3-aminopropyltriethoxysilane (APTES) into the reactor, raising the temperature in the reactor to 75-85° C., and performing a heat preservation reaction for 20-50 minutes;
• after a material in the reactor is cooled to room temperature, the material is a new material produced by paraformaldehyde, formaldehyde solution, polyvinyl alcohol, solid melamine powder and 3-aminopropyltriethoxysilane in step (1) and step (2), adjusting the pH value of a solution of the new material in the reactor to be 3-4 by adding an acid;
• heating the new material solution, performing a heat preservation reaction for 40-80 minutes when the temperature rises to 80-95° C., and then judging an end point of the reaction by testing the cloud point of the new material solution;
• when the reaction ends, immediately adding alkali to adjust the pH value in the reactor to be 8.5-9.0, thereby obtaining a semi-rigid modified melamine resin;
• step (3):
• curing and foaming:
• feeding a foaming agent, emulsifier, auxiliary agent and curing agent into a stirring reactor, and uniformly stirring and mixing to obtain a mixed auxiliary agent;
• pumping the mixed auxiliary agent and the semi-rigid modified melamine resin into an emulsifying machine to mix and emulsify, thereby forming an emulsified resin;
• placing the emulsified resin into a microwave heating chamber and performing microwave foaming, thereby forming a semi-rigid melamine foam plastic product with a high-density open-cell structure;
• step (4):
• cutting and drying:
• cutting the semi-rigid melamine foam plastic product obtained in step (3) through a cutting machine and then drying, thereby obtaining a finished semi-rigid melamine foam plastic product.