A xylylene diisocyanate (XDI) composition according to exemplary embodiments includes xylylene diisocyanate and an acidity regulator having a boiling point of 110? C. or higher, and the composition has an acidity of greater than 100 ppm and 1,000 ppm or less based on a total weight of the xylylene diisocyanate (XDI). An optical lens having a high transmittance and improved optical uniformity can be manufactured by controlling a polymerization reaction rate through acidity adjustment.

A xylylene diisocyanate (XDI) composition according to exemplary embodiments includes xylylene diisocyanate and an acidity regulator having a boiling point of 110? C. or higher, and the composition has an acidity of greater than 100 ppm and 1,000 ppm or less based on a total weight of the xylylene diisocyanate (XDI). An optical lens having a high transmittance and improved optical uniformity can be manufactured by controlling a polymerization reaction rate through acidity adjustment.

The present invention relates to a process for separating an isocyanate prepared by reaction of a primary amine with an excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, wherein (i) the gaseous crude product is partially liquefied by contacting with a quenching liquid, (ii) the gas phase obtained in step (i) is partially condensed, (iii) the condensate obtained in step (ii) is used as the quenching liquid in step (i), (iv) the portions of the gas phase that were not condensed in step (ii) are at least partially liquefied, (v) the liquid phase obtained in step (iv) is likewise used as the quenching liquid in step (i), and (vi) the liquid phase obtained in step (i) is worked up to the pure isocyanate without previously being used as quenching liquid.

The present invention relates to a process for separating an isocyanate prepared by reaction of a primary amine with an excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, wherein (i) the gaseous crude product is partially liquefied by contacting with a quenching liquid, (ii) the gas phase obtained in step (i) is partially condensed, (iii) the condensate obtained in step (ii) is used as the quenching liquid in step (i), (iv) the portions of the gas phase that were not condensed in step (ii) are at least partially liquefied, (v) the liquid phase obtained in step (iv) is likewise used as the quenching liquid in step (i), and (vi) the liquid phase obtained in step (i) is worked up to the pure isocyanate without previously being used as quenching liquid.