| 摘要 |
<p>The diisocyanate (I) is purified using organic solvents (II) by storing (I) after manufacture until a yellow colour develops, and dissolving crude (I) in solvent of dielectric constant below 4.5 at 0.125 degrees C, separating the yellow solids from the solution and recrystallising the product. (II) pref. mixtures of opt. halo aliphatic solvents esp. 5-12C aliphatic and/or perchlorethylene which are non-polar or slightly poalr, and aromatic hydrocarbons and/or aliphatic monoethers R-O-R where R is alkl of 2-6C or cycloalkyl. Amount of 5-12C aliphatic hydrocarbons are 2-10 times the amount of (I). The product is used in prodn. of polyurethane elastomers, fibres, and synthetic leather.</p> |
