Water-dispersible amphoteric polyurethane, preparation method therefor, and use thereof in reinforcing concrete

A water-dispersible amphoteric polyurethane, characterized in that, prepared from Component A, B, C, D and E through polymerization and chain-extension reaction:

• Component A, polyisocyanate compound;
• Component B, selected from polyester polyol, polyether glycol, polycarbonate glycol or polyacrylate glycol;
• Component C, diol compound containing an anionic group or a potential anionic group;
• Component D, tertiary or quaternary amine cationic group compound containing at least two active H functional groups;
• and
• Component E, polyamine compound containing polyoxyethylene as shown in structural formula (9),
• wherein, R and R′ are alkyl containing 1˜6 carbon atoms;
• y is an integer from 5 to 400, (x+z) is an integer from 0 to 100;
• if (x+z)≠0, Component E is random copolymer or block copolymer;
• wherein, the molar ratio of Component D to C, namely D/C, is 1:20˜20:1;
• the molar ratio of Component E to B, C and D, namely E/(B+C+D), is 1:100˜20:100;
• and the molar ratio of the isocyanate groups in Component A to the total amount of the active H functional groups in Component B, C, D and E is 2.0:0.6˜2.0:1.8.