Synthesis And Application Of Aqueous Polyurethane Blocking Agents Of Oximes

The oximes for isocyanate masking ,one of the methods of preparing waterborne polyurethane, has been usually used as across-linker in hydroxy resin in recent years. From that they can be made as adhesives, coatings, widely used in the timber industry , The flexible packaging industry, automobile industry, shoe-making industry, plastic industry and architectural industry. For example, MEKO, acetone oxime, acetophenone oxime, 2, 6-dimethyl-4-heptylketoxime,the blocking agents of IPDI, all can be used as the components of coatings. And in glass fibers masked water dispersing-ployisocyanate by MEKO can be used. There are also some kinds of waterborne polyurethane can be modified to be the dyestuff, batteries, medical materials, etc.This article prepared two series of oxime compounds: acetaldoxime, acetone oxime, butanone oxime, pentanone oxime, cyclopentanone oxime, cyclohexanone oxime and pyruvate oxime, glyoxylate oxime, 2-oxocyclopentane acetic acid oxime. It is focused on the impact factors of pyruvate oxime to get the best reaction conditions.Then these two series oxime compounds were done closed HDI experiment. It is discussed various oxime compound closed reaction conditions.Then blocked HDI by these two series oxime compounds were done octanol experiment. The first six compounds do not contain emulsion group, hydrophobic that it is difficult to form emulsion and to make water-based polyurethane being blocking agent alone. After three compounds containing emulsion group, blocked polyurethane to form emulsion, which exhibiting a high release temperature, are not blocking agent alone either.This followed the series Oxime compound emulsion experiment, the results is that the waterborne polyurethane emulsion stability of the former six compounds are worse than the latter three compounds.As the disadvantage of these two series oxime compounds, they are complex. Focus on the ratio of pyruvate oxime to acetone oxime and butanone oxime which were done closed isocyanate experiments and emulsion experiment. From the experimental results we can be found the most stable form of waterborne polyurethane emulsion, the minimum temperature of the closure of the best ratio on, acetone oxime: pyruvate oxime to 95:5, octanol experimental determination of its temperature is the same with acetone oxime. It will become a waterborne polyurethane blocking agent with lower block temperature.