Thermally reversible crosslinked polyurethane containing dicyclopentadiene crosslinking bridged bonds, and preparation method and applications thereof

Abstract

The invention provides thermally reversible crosslinked polyurethane containing dicyclopentadiene crosslinking bridged bonds, and a preparation method and applications thereof. Dicyclopentadiene dicarboxylic acid and polyisocyanate (I) carry out reactions to generate a terminal isocyanate component, which contains a dicyclopentadiene structure and is taken as a crosslinking agent, and the terminalisocyanate component and a terminal hydroxyl component carry out reactions to form a crosslinked polyurethane network. By introducing dicyclopentadiene bridged bonds into polyurethane, at a high temperature, bridged bonds are broken; at a low temperature, bridged bonds are formed again; and repeated processing of chemical crosslinking type polyurethane is realized. The primary reverse Diels-Alderreaction temperature of dicyclopentadiene bridged bonds is 170 DEG C; and dicyclopentadiene bridged bonds are introduced into polyurethane to realized thermoplastic processing of crosslinking type polyurethane in a temperature range of 170 to 210 DEG C. The prepared thermally reversible polyurethane has an excellent repeated processing property, and still has good mechanical properties after manytimes of processing and moulding.

Description

technical field [0001] The invention relates to the field of polymer materials, in particular to a thermally reversible crosslinked polyurethane containing dicyclopentadiene crosslinked bridges, a preparation method and an application thereof. Background technique [0002] Polymer materials can be divided into linear polymers and cross-linked polymers from the molecular structure. Linear polymers are characterized by their fluidity at elevated temperatures, enabling repeated processing. The molecular structure of cross-linked polymers is in the form of a three-dimensional network. Once the material is formed, it cannot be processed by thermoplastic again. [0003] Polyurethane is a kind of polymer with urethane bonds in its molecules. There are hydrogen bonds between molecules, forming a microscopic phase separation structure with coexistence of "soft segment" and "hard segment", which has excellent performance. Polyurethane is usually obtained by reacting isocyanate, poly...

AI Technical Summary

Problems solved by technology

If the decrosslinking temperature is too high, the processing temperature of the crosslinked polymer will inevitably rise, which will lead to high temperature thermal oxygen aging of the polymer

If the decrosslinking temperature is too low, the heat-resistant temperature of the crosslinked polymer is low, and it is difficult to use it as an elastomer material, especially the decrosslinking temperature of polyurethane crosslinked by disulfide bonds and diselenium bonds is basically between room temperature and 100 Between ℃ (CN106589289A, CN108503782A, CN106750115A), the heat resistance of the material is very poor

Acylhydrazone bond cross-linked polyurethane (CN107236106 A) also has the problem of poor heat resistance

It can be seen that the existing thermally reversible cross-linked polyurethane material manufacturing technology is still unable to obtain cross-linked polyurethane thermoplastic elastomers that meet the requirements of thermoplastic elastomer materials in terms of thermoplastic processing temperature and material heat resistance

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