| 摘要 |
Acetals of polyvinyl alcohol (PVAL) which contain vinyl oxoacetal units of the formula I which are derived from aldehydes containing keto groups (oxoalkanals) and can be crosslinked with hydrazine or polyfunctional hydrazine derivatives or polyfunctional carboxylic acid hydrazides via their keto groups to give high molecular weight products having a variable spectrum of properties are described. Mixed acetals with aldehydes which contain no keto groups can also be prepared and can be crosslinked via the keto groups of the vinyl oxoacetal units. Products which are obtained from PVALs and oxoalkanals or low molecular weight acetals of the oxoalkanals and contain vinyl oxoacetal units are preferably prepared in aqueous or organic media under acid catalysis. For the use of polyvinyl oxoacetals according to the invention, preferably as polymeric binders and coating agents, these can preferably be employed in dissolved or dispersed form, with addition of the abovementioned crosslinking agents, for a number of fields of use, it being possible for the crosslinking to be carried out during or after drying of these solutions or dispersions to form sparingly soluble and swellable or insoluble and non-swellable polymeric modifications having surprisingly advantageous properties. |
