Novel process for preparing p-phenylene diisocyanate (PPDI) based on phosgene

A p-phenylene diisocyanate, a new process technology, applied in the field of preparation of chemical raw materials, can solve the problems of slow reaction process, environmental pollution, complex production process, etc., to achieve the effect of reducing pollutant emissions and avoiding slow reaction

Inactive Publication Date: 2010-02-03
XINYI AGRI CHEM PLANT JIANGSU PROV
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  • Abstract
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  • Application Information

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Problems solved by technology

However, its preparation technology has not been developed as it should be, and its preparation method and technology are relatively backward at present.
Th...

Method used

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  • Novel process for preparing p-phenylene diisocyanate (PPDI) based on phosgene
  • Novel process for preparing p-phenylene diisocyanate (PPDI) based on phosgene
  • Novel process for preparing p-phenylene diisocyanate (PPDI) based on phosgene

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Embodiment Construction

[0016] This specific embodiment adopts the following technical process steps: 1, hydrochloric acid generating reaction; 2, salt-forming reaction; 3, photochemical reaction;

[0017] Described hydrochloric acid generation reaction is will quantitative POCl 3 Vacuum into the metering tank, put a certain amount of hydrochloric acid in the hydrochloric acid generator, and slowly add POCl dropwise 3 The reaction generates HCl, and the reaction formula is as follows: POCl 3 +3H 2 O→H 3 PO 4 +3HCl;

[0018] The salt-forming reaction is to put a certain amount of solvent o-dichlorobenzene into a salt-forming reaction kettle, add a certain amount of p-phenylenediamine to heat in a full reflux state, dissolve p-phenylenediamine, pass a certain amount of HCl, and take a sample to test the pH. When the pH value is between 3 and 4, the salt formation is over, and the tail gas is removed and broken. The reaction formula is as follows:

[0019]

[0020] In the photochemical reaction...

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Abstract

The invention provides a novel process for preparing p-phenylene diisocyanate (PPDI) based on phosgene, which relates to a process for preparing chemical raw materials, in particular to a novel process for preparing the p-phenylene diisocyanate (PPDI). The process comprises the following steps: 1, hydrochloric acid formation reaction; 2, salifying reaction; and 3, photochemical reaction which is to transfer a mixture solution of para-phenylene diamine dihydrochloride-o-dichlorohenzene to a photochemical kettle, control the temperature, introduce the phosgene in an infinite reflux state to react, determine that the reaction is terminated after reaction materials are settled, introduce quantitative nitrogen to remove acid, sample and analyze the reactant, and obtain the p-phenylene diisocyanate PPDI through rectifying, crystallizing, centrifugating, drying, packaging or refining, slicing and packaging when the acidity content is qualified. In the process, a reasonable salifying reactioncondition is customized to avoid slow reaction of a prepolymer, complicated reaction mechanism, and easy generation of side products and adverse factors influencing the reaction in the next step.

Description

Technical field: [0001] The invention relates to a process for preparing chemical raw materials, in particular to a new process for preparing p-phenylene diisocyanate (PPDI). Background technique: [0002] P-phenylene diisocyanate (PPDI), chemical structural formula: [0003] [0004] Relative molecular weight: 160.13; quality index: ≥98% [0005] P-phenylene diisocyanate (PPDI) is a white to light yellow flaky solid with an NCO content of 52.5%. The melting point is 94-95°C, the boiling point is 260°C, and the density (g·cm-3) is 1.4407 (20°C). [0006] The isocyanate has high reactivity and reacts with hydroxyl groups, amine groups and water to form polyurethane or polyurea. Produced by phosgenation of p-phenylenediamine, it is a raw material for high-performance thermoplastic and castable polyurethane. [0007] P-phenylene diisocyanate (PPDI) is a new high-performance special PU curing agent. In its structure, in addition to the benzene ring, there are two symmetri...

Claims

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Application Information

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IPC IPC(8): C07C265/14C07C263/10
Inventor 梁华中陈弘祥
Owner XINYI AGRI CHEM PLANT JIANGSU PROV
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