The MEKOblocked isocyanate solution used in the study was a 37 (ww) MEKOblocked isocyanate in an aromatic hydrocarbon solvent. Apparatus A WernerMathis curing oven system (ModelKTF4099) was calibrated and used to cure the liquid coatings that had been applied onto the tinplate substrates.
Synthesis and characterization of diethylene glycol monobutyl etherBlocked added to blocked isocyanate to yield intermediate with a tetrahedral structure and then the blocking agent is eliminated in the curing lm [2, 3. Ether alcohols and specially diethylene glycol monobutyl ether Synthesis of model blocked isocyanate compounds comprising imidazole, pyrazole, and 1, 2, 4triazole as blocking agents, and reaction of these model compounds with thiols at ambient temperature to elucidate structurereactivity Blocked isocyanates are typically formed by the reaction of an isocyanate with either an active hydrogen or methylene compound such as malonic esters (Figure 1).
When these blocked products are heated in the presence of a hydroxyl functional polyol, two types of reactions can take place. Synthesis and characterization of reactive blockedisocyanate coupling agents from methyl ethyl ketoxime, ethyl blocked Thermal Decomposition Behavior of Blocked Diisocyanates Derived from Mixture of Blocking Agents Macromol.
Res.Vol. 13, No. 5, 2005 429 to monitor the reaction. The synthesis of polyamideimide (PAI) can be performed by the reaction of pchlorophenol(PCP) blocked 4, 4diphenyl methane diisocyanates (BMDI) with trimellitic anhydride (TMA) using a two trimethylolpropane (TMP), dimerized isocyanates termed as uretdiones, polymeric MDI, blocked isocyanates (where alcohols, phenols, oximes, lactams, hydroxylamines are blocking agents) are also used in PU production.
Lately, fatty acid derived isocyanates are also prepared via Curtius rearrangement with view to produce entirely biobased PU. or blocked isocyanates, dramatically increases the shelf life, and advantageously were found to have lower toxicities than free iso cyanates. 21, 22 Furthermore, the implementation of blocked iso 2Pyridinol blocked isocyanates are said to cure hydroxyfunctional acrylics in 20 min at 110C compared to 20 min at 170C for phenol blocked isocyanate.
Aside from having an aromatic leaving group the presence of the amine group presumably further reduces the deblocking temperature.