| 摘要 |
The invention relates to acetals of polyvinyl alcohol (PVAL) which contain vinyloxoacetal units of the formula I which are derived from keto-containing aldehydes (oxoalkanals) and can be crosslinked via their keto groups by means of hydrazine or polyfunctional hydrazine derivatives or polyfunctional carboxylic acid hydrazides to give high-molecular-weight products having a variable property profile. It is also possible for mixed acetals with keto-free aldehydes to be prepared and crosslinked via the keto groups of the vinyloxoacetal units. The preparation of vinyloxoacetal unit-containing products from PVALs and oxoalkanals or low-molecular-weight acetals of oxoalkanals is preferably carried out in aqueous or organic media with acid catalysis. For the preferred use of polyvinyloxoacetals according to the invention as polymeric binders and coating compositions, they can preferably be employed, for a number of areas of application, in dissolved or dispersed form with addition of the abovementioned crosslinking agents, it being possible for the crosslinking to be carried out during or after drying of the solutions or dispersions with formation of sparingly soluble and swellable or insoluble and non-swellable polymeric modifications having surprisingly advantageous properties. |
