Authors: Liu Dubao, Tang Deng, Zhang Wenrong and Xu Gowen (College of Chemistry and Chemical Engineering, Anhui University, Key Laboratory of Green Polymer Materials, Anhui Province)

 

ABSTRACT: Solvent-free waterborne polyurethane resin was synthesized from Dihydroxymethyl butyric acid (DMBA), isophorone diisocyanate (IPDI) and polypropylene glycol oxide (PPG-220) by prepolymer method, and compared with WPU synthesized by DMPA. The effects of R value, chain extender and the amount of chain extender on the properties of PU emulsion and film were discussed. The synthetic process was also studied. DSC thermodynamics analysis and IR spectrum characterization were carried out. The ATR infrared spectrum of the film showed the typical infrared characteristic of waterborne polyurethane. Research conclusions:

 

(1) In the process of synthesizing waterborne polyurethane with DMBA, the whole reaction process can be completed without adding a little solvent, and the reaction results conform to the formula design.

 

(2) when the formula is designed, the R value is above 1.3, the resin can emulsify, and the waterborne polyurethane emulsion has good appearance, good mechanical properties and good dielectric resistance.

 

(3) NCO conversion test shows that the NCO conversion rate of one-step method is higher than that of two-step method, and the NCO conversion rate can reach more than 98% in the whole reaction time of only 5 hours, no matter one-step method or two-step method.

 

(4) The post-chain extension process can reduce the viscosity of prepolymer during emulsification, increase the mechanical strength of the film than EDA, while the breaking elongation is smaller than EDA.

 

(5) Waterborne polyurethane synthesized by DMBA can complete the reaction without or with only a few solvents, which greatly reduces the environmental pollution of solvents, reduces the hidden danger of plant safety, reduces the difficulty of removing solvents, reduces the cost of the whole production, and increases the market competition advantage.

 

(Source: Journal of Anhui University Natural Science Edition, Volume 32, No. 5, September 2008)