The Waterborne Modification Of Nonisocyanate Polyurethanes And Their Applications

Polyurethane （PU） is widely used as foam, rubber, elastomer, fiber, adhesive,coating and so on, for its excellent properties such as impact resistance, adhesion,wearable and stress relaxation. Traditional synthesis of PU is based on the reactionbetween polyols and polyisocyanates. However, polyisocyanates are quite harmful tothe environment and human beings for their toxicity and volatility. More severely,the production of isocyanates involves the use of phosgene which is highly toxic.Furthermore, isocyanates are sensitive to moisture and emit CO₂when come incontact with water and it causes unexpected bubble formation in PU products.Oil-based coatings contain large amounts of organic solvents. They are easilyburned and explosive, and are quite harmful to the environment when used. Also, it’sa serious waste of resources. Since, waterborne coatings can overcome thesedisadvantages so they are now getting used in the trends of coating field.In our work, we have synthesized PU in a non-isocyanate route, in which cycliccarbonates react with primary amines, namely non-isocyanate polyurethane （NIPU）.The key monomers, cyclic carbonates, can be produced by CO₂and epoxycompounds, which can reduce the emission of greenhouse gas. Based on the cycliccarbonate methacrylate （CCMA） as functional monomer, three kinds of two-packwaterborne NIPU systems, which included self-emulsification system, water solublesystem as well as emulsion system, were prepared by different waterborne resinsynthesis techniques.1、NIPU self-emulsification system was prepared with vinylpyrrolidone （NVP）as hydrophilic monomer. The effect of hydrophilic monomer to the reaction betweencyclic carbonate with amine was investigated. Stable NIPU precursor emulsion wasobtained, when NVP was35wt%, but with poor dilution stability which was provedby DLS and TEM. FT-IR spectrum proved that cyclic carbonate side groups of thepolymers had reacted with hexanediamine （HDA） to produce NIPU. The adhesion ofthe NIPU coating was of0grade. Pencil hardness reached2H and petrol resistancewas more than48h. But water resistance and impact resistance were very poor.2、CCMA first was reacted with ethylenediamine to produce a monomer （M）containing two hydroxylurethane groups, then M copolymerized with MAA and other monomers to obtain a water soluble NIPU system. Aziridinecrosslinker（SaC-100） was used to enhance the coating’s properties. The synthesiscondition of M was investigated and its structure was proved by FT-IR spectrum.The amounts of M, MAA and SaC-100were optimized. The adhesion of the NIPUcoating was of0grade. Impact resistance was higher than50cm. Pencil hardnessreached2H, petrol resistance was more than48h and water resistance was2.5h.3、NIPU precursor emulsion was prepared by seed emulsion polymerization.DLS and TEM showed that the latex particles were small （110nm） and uniform（PDI=0.15）. FT-IR spectrum proved that cyclic carbonate side groups of thepolymers had reacted with HDA to produce NIPU. The adhesion of the NIPUcoating was of0grade. Impact resistance was higher than50cm with high pencilhardness （4H）. Petrol resistance was more then288h and water resistance was168h.Among the waterborne NIPU systems mentioned above, the properties of theemulsion system, which was expected to achieve industrial production and used incoating field, were the best.