Method for preparing 1, 5-pentamethylene diisocyanate with low hydrolytic chlorine content

Abstract

The invention discloses a method for preparing 1, 5-pentamethylene diisocyanate with low hydrolytic chlorine content, which comprises the following steps: dissolving phosgene in a solvent at low temperature until saturation, continuing introducing phosgene, adding a mixed solution of bio-based 1, 5-pentanediamine and a solvent into the phosgene solution through a metering pump, and carrying out temperature programming after dropwise adding is completed, controlling the reaction temperature and time to obtain a photochemical liquid containing 1, 5-pentamethylene diisocyanate, after the reactionis completed, carrying out reduced pressure distillation to remove the solvent, and continuously carrying out reduced pressure distillation to obtain a colorless liquid, namely 1, 5-pentamethylene diisocyanate. The method has the beneficial effects that the 1, 5-pentamethylene diisocyanate product with low hydrolytic chlorine (less than 50ppm) is obtained, can be directly used for downstream application, is simple in operation process and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of chemical synthesis, and relates to a method for synthesizing low-hydrolysis chlorine 1,5-pentane diisocyanate by direct phosgenation. Background technique [0002] Polyurethane materials prepared from aliphatic isocyanates have excellent mechanical properties, outstanding chemical stability and excellent weather resistance, and are widely used in high-grade building exterior wall coatings, automotive coatings, product shell coatings, industrial equipment pipes, thermal insulation materials, foam Plastics, synthetic fibers, coatings and solid elastic materials, as well as light industrial products closely related to people's lives, such as shoemaking, synthetic leather, insulation materials and waterproof materials for refrigerators, etc. Compared with aromatic isocyanates MDI and TDI, aliphatic isocyanates have better performance and lower toxicity, and are mainly used in the production of high-end or special polyu...

AI Technical Summary

Problems solved by technology

Moreover, PDA, the raw material of PDI products, can be prepared by biological methods, which avoids the disadvantages of complicated HDI raw material HDA process and high technical difficulty. At present, there is no industrial production device for 1,5-pentanediisocyanate in the world. The construction of 1,5-pentane diisocyanate and its industrial development will also attract widespread attention

[0004] Mitsui Chemicals Co., Ltd. patent CN 103347852A discloses "Pentamethylene diisocyanate, manufacturing method of pentamethylene diisocyanate, polyisocyanate composition, polyurethane resin and polyurea resin", and reports that bio-based pentamethylenediamine is directly photochemical or photochemical after salt formation Research on the synthesis of 1,5-pentanediisocyanate. The 1,5-pentanediamine produced by the biological method contains tetrahydropiperidine and other impurities, resulting in 1,5-pentanediisocyanate products containing acid chlorides, resulting in high hydrolyzed chlorine indicators , can not meet the index requirements of HDI equivalent products, which directly affects downstream applications. Although the author proposes that adding additives under high-temperature heat treatment (220-250°C) in an inert gas atmosphere can reduce the hydrolyzed chlorine index of the product, but this method causes The product yield is reduced, the process conditions are harsh, and it is difficult to industrialize