Polyurethane-urea elastomers are made using as a chain extender 2-methyl-1,3-propanediol-bis-p-aminobenzoate which is the reduction product from hydrogenating 2-methyl-1,3-propanediol-bis-p-nitrobenzoate. The latter composition is preferably made by esterifying p-nitrobenzoic acid and 2-methyl-1,3-propanediol using a stoichiometric excess of the diol initially, adequate to render the reaction mixture processible, and after converting to a nonvolatile form sufficient diol to form diester with substantially all of the acid, removing free diol by distillation while continuing the esterification of unreacted acid and transesterification of monoester formed to diester. This process, which can be applied broadly to esterification of other nitroaromatic acids with other aliphatic diols, produces high yields of diester without needing extraneous solvent for processibility and with only water as a by-product. The 2-methyl-1,3-propanediol-bis-p-aminobenzoate exhibits reactivity and processing characteristics which make it a suitable drop-in replacement for MoCA in polyurethane-urea elastomer manufacture.
聚
氨酯-
尿素弹性体是用
2-甲基-1,3-丙二醇-双
对氨基苯甲酸酯作为扩链剂制成的,后者是
2-甲基-1,3-丙二醇-双
对硝基苯甲酸酯氢化后的还原产物。后一种组合物最好是通过
对硝基苯甲酸和
2-甲基-1,3-丙二醇的酯化反应制成,最初使用足够使反应混合物可加工的过量二元醇,然后将足够的二元醇转化为非挥发性形式,与基本上所有的酸形成二酯,通过蒸馏除去游离二元醇,同时继续酯化未反应的酸,并将形成的单酯转酯化为二酯。这种工艺可广泛应用于其他硝基芳香族酸与其他脂肪族二元醇的酯化反应,可产生高产率的二酯,无需外加溶剂进行加工,副产物只有
水。
2-甲基-1,3-丙二醇双
对氨基苯甲酸酯的反应性和加工特性使其成为聚
氨酯
尿素弹性体生产中 MoCA 的合适替代品。