Authors: Zeng Jun, Wang Wusheng, Ruan Deli, Zhong Feng (Applied Chemistry Research Center, Anhui University; Anhui University Kezhao Fine Chemical Plant)
Abstract: Using DMBA and DMPA as hydrophilic monomers to prepare polyurethane emulsions, this article compares their emulsion and film properties, discusses the reasons, and provides a reference for industrial production.
The tests covered the following property comparisons:
1. Solubility comparison of DMBA and DMPA
It was found that the dissolution behavior of DMBA and DMPA in polymer polyols is less affected by the relative molecular weight of the polymer polyols, but their dissolution temperatures differ greatly. The dissolution temperature of DMPA is 145–150℃; below this temperature it slowly precipitates out, while that of DMBA is 80℃, and once dissolved there is no precipitation upon cooling. This is because DMBA has a lower melting point (=108–113℃), while DMPA has a higher melting point (=175–188℃).
2. Comparison of polyurethane emulsion properties
DMBA and DMPA polyurethane emulsions were characterized by solid content, pH, viscosity, thermal stability, and appearance. Results are shown below:
| Formula No. | Solid Content (%) | pH | Viscosity (mPa·s) | Thermal Stability (60℃×72h) | Emulsion Appearance |
| A-10 A-15 A-20 |
25.2 25.1 25.4 |
8.1 8.2 8.4 |
4.2 5.1 5.7 |
No gelation No gelation No gelation |
White, slight precipitate |
| B-10 B-15 B-20 |
25.3 25.2 25.0 |
8.2 8.3 8.4 |
4.4 6.0 6.2 |
No gelation No gelation No gelation |
Milky white |
Note: A and B represent DMPA and DMBA respectively; 10, 15, and 20 represent carboxyl contents of 1.0%, 1.5%, and 2.0%; formula: hard segment content 48%.
3. Comparison of reactivity of DMBA and DMPA;
4. Comparison of mechanical properties of polyurethane emulsion films;
5. Comparison of water resistance, chemical resistance, and low-temperature resistance of polyurethane emulsion films;
Based on the above comparisons, 2,2-dimethylolbutanoic acid has the following characteristics:
(1) Lower dissolution temperature in polyether or polyester polyols, generally about 80℃, independent of the relative molecular weight of the polymer polyols, facilitating homogeneous reaction;
(2) Experiments and IR analysis show that the polyurethane reaction time of the DMBA system can be shortened;
(3) Polyurethane films prepared from DMBA have high strength and high elasticity
