Preparation method of microporous PMI (polymethacrylimide) foam and PMI foam prepared by method

Abstract

The invention discloses a preparation method of microporous PMI (polymethacrylimide) foam and PMI foam prepared by the method. The method comprises the following steps: (1) uniformly mixing reaction monomers, a third monomer, an initiator, a foaming agent and a crosslinking agent according to the proportion to obtain a mixed solution; (2) injecting the obtained mixed solution into a closed vessel, carrying out prepolymerization to obtain a transparent prepolymerization plate body, and carrying out post polymerization on the transparent prepolymerization plate body; and (3) putting the transparent prepolymerization plate body subjected to post polymerization in a drying oven provided with an ultrasonic generator, carrying out ultrasonic nucleation, and foaming at constant temperature. No nucleation substance, such as the white carbon black, foaming agent, toughening monomer or the like, is added, so the cost is low; and the strength is not lowered, but the toughness is enhanced. The pore size of the foam can be freely regulated within the range of 10-100 mu m; and the technique is simple, and only needs to regulate the ultrasonic frequency.

Description

technical field [0001] The invention relates to the technical field of polymer materials, in particular to a preparation method of a high-performance polymethacrylimide microporous material and a product thereof. Background technique [0002] Polymethacrylimide (PMI) foam is a high-performance foam with (meth)acrylic acid / (meth)acrylonitrile copolymer as the matrix resin. Under the same density, PMI foam is the foam with the highest strength and rigidity among commercial foams; from the perspective of molecular structure, the carboxyl and nitrile groups on the main molecular chain of PMI make hydrogen bonds between the molecular chains, methyl The steric hindrance of carboxyl and nitrile groups makes the molecular chain rigid, and the six-membered imide ring greatly increases the rigidity of the molecular chain, accompanied by cross-linking between molecular chains; from the perspective of cell structure, PMI foam plastics The cell wall structure of the cells presents a typ...

AI Technical Summary

Problems solved by technology

Heterogeneous nucleation (DE10212235.0) is carried out by adding an insoluble nucleating agent such as white carbon black to prepare a small-cell foam. This method has high nucleation efficiency, but the main defect is that, on the one hand, the insoluble nucleating It is easy to settle during the preparation process, resulting in uneven foam board, on the other hand, the addition of insoluble nucleating agent reduces the strength of the material

For example, in order to suppress the sedimentation of the nucleating agent, it is generally thickened by adding high molecular weight polymers such as PMMA. Although the sedimentation performance can be solved, the performance of the foam will be greatly reduced.

In addition, there are also small-cell foams prepared by changing the amount of foaming agent (DE2726260), but the foam density obtained in this way is low, and for some special molding processes, the foam cells obtained by this method are still too large

In addition, it has been introduced in related reports that the size of the cells can be adjusted by adding toughening monomers. This method can better control the size of the cells, but the performance of the resulting foam is greatly reduced.

Images