Synthesis Of UV Curable Waterborne Polyurethane Acrylate Coatings

Synthesis Of Waterborne Polyurethane Acrylate

The oligomer in uv-wpua coating is wpua, which is the main part of the coating. Wpua is generally formed by reaction of polyisocyanate, diol and hydroxyl acrylate. Isocyanates include aromatic isocyanates, aliphatic isocyanates and alicyclic isocyanates, which affect the rigidity, weather resistance and yellowing resistance of wpua. Diols mainly include polyether diols and polyester diols, which affect the tensile strength, softness, heat resistance and hydrolysis resistance of wpua.
The - NCO group in the polyisocyanate reacts with the hydroxyl group of the diol to form an oligomer with isocyanate groups at both ends. 2. 2,2-dihydroxymethylpropionic acid (DMPA) is used as the diol to introduce hydrophilic groups into the oligomer, and 1,4-butanediol (BDO) is added for chain extension; 3. Hydroxyethyl acrylate (HEA) was used to introduce photo active groups containing unsaturated double bonds for UV curing. After the three-step reaction is completed, triethanolamine (teoa) is added for neutralization reaction, and finally water is added to emulsify it into lotion.
Other scholars have synthesized uv-wpua with excellent performance by using synthetic raw materials such as Polyhexylene glycol, isophorone diisocyanate, PETA, and dimethylbutyric acid (DMBA). Three kinds of wpua were synthesized from the prepared polyacrylate with carboxyl group in side chain, polyether polyol, isophorone diisocyanate and hydroxyethyl acrylate. After comprehensive investigation of physical test and application test, it is considered that the comprehensive performance of polyether wpua is better. Using toluene diisocyanate, polyhexanediol, 2,2-dihydroxymethylpropionic acid and hydroxyethyl methacrylate as raw materials, prepolymer was first synthesized, then triethylamine was added as neutralizing agent, and water was used as chain extender to disperse in water to form stable wpua lotion.