A kind of method adopting rear chain extender to prepare waterborne polyurethane
A water-based polyurethane, post-chain extension technology, applied in the field of polyurethane
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Embodiment 1
[0026] Embodiment 1 A kind of method that adopts post-chain extender to prepare waterborne polyurethane
[0027] Include the following steps:
[0028] (1) Add polyol, isocyanate, catalyst
[0029] Dehydrate 50 parts by mass of polyol under vacuum at 80°C and 0.09Mpa for 2.5 hours, adjust the reaction temperature to 85°C, add 34 parts by mass of isocyanate according to the proportion, add 0.1 part by mass of catalyst after reacting for 1 hour, and continue the reaction for 1 hour;
[0030] Described catalyst is dibutyltin dilaurate;
[0031] Described polyhydric alcohol is polytetrahydrofuran diol;
[0032] The isocyanate is isophorone diisocyanate.
[0033] (2) Add hydrophilic chain extender and solvent
[0034] Add 6.5 parts by mass of hydrophilic chain extender and 5 parts by mass of solvent, and react at 80°C for 2 hours;
[0035] The hydrophilic chain extender is 2,2-dimethylolpropionic acid (DMPA);
[0036] The solvent is N-methylpyrrolidone.
[0037] (3) neutraliz...
Embodiment 2
[0046] On the basis of embodiment 1, only change the kind of rear chain extender, adopt EDA and A50 to test as rear chain extender, test result is as follows:
[0047] Table 1 Appearance and stability of waterborne polyurethane emulsion
[0048]
[0049] When the amount of DMPA is the same, after adding the chain extender, the emulsion changes from transparent to translucent emulsion, and the three emulsions have good stability after stability testing.
[0050] Particle size and viscosity of table 2 aqueous polyurethane emulsion
[0051]
[0052] When the amount of DMPA is the same, adding EDA as a post-chain extender can reduce the viscosity of the emulsion and have a proper effect on increasing the particle size of the emulsion. When A50 is used as a post-chain extender, it can reduce the viscosity of the emulsion and significantly reduce the particle size of the emulsion.
[0053] Table 3 Mechanical properties of waterborne polyurethane
[0054]
[0055] When the...
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