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Method for continuous preparation of 1,6-hexamethylene diisocyanate

A technology of hexamethylene diisocyanate and hexamethylene carbamate, which is applied in the field of continuous preparation 1, can solve problems such as environmental pollution, difficulty in separation, and high boiling point of solvents, and achieve recycling of by-products and solvents, Environmentally friendly process and short reaction time

Inactive Publication Date: 2009-07-29
CHENGDU ORGANIC CHEM CO LTD CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the phosgene method is the main industrial route for preparing HDI, but there are many problems in the production process: because phosgene is a highly toxic gas, a series of engineering and technical problems such as safety and environmental protection in the production process are difficult to completely solve; if the absorption process is not perfect , in the phosgene method, a large amount of by-product hydrogen chloride will leak, causing environmental pollution and the by-product hydrogen chloride will seriously corrode the equipment in the production process, so the requirements for the material of the equipment are high, and the corresponding investment is relatively large; HDI produced by the phosgene method The product contains hydrolyzed chlorine, which affects the application performance of the product
[0010] The solvents used in the above invention generally have a higher boiling point and are more difficult to separate from isocyanate products

Method used

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  • Method for continuous preparation of 1,6-hexamethylene diisocyanate
  • Method for continuous preparation of 1,6-hexamethylene diisocyanate
  • Method for continuous preparation of 1,6-hexamethylene diisocyanate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] First, the air in the reaction system was replaced with nitrogen, and the temperature of the heating oil in the jacket of the scraper falling film evaporator was raised to 280°C. A mixture of N,N-dimethylaniline and toluene (blank inert solvent, weight ratio 1:1) preheated to 120°C was passed into a single-tube scraped falling film evaporator at a flow rate of 100 g / h to form a falling film evaporator. The film is vaporized, the speed of the scraper is kept at 120rpm, the temperature of the inner wall of the evaporator is controlled at 235-245°C, and the system pressure is stabilized at 0.5-0.6MPa. After the system is stable, switch the above blank inert solvent with 1,6-hexamethylene dicarbamate methyl ester solution (10g hexamethylene dicarbamate methyl ester / 100g above mixed solution) preheated to 120°C, The flow rate of 110g / h is passed into the scraper falling film evaporator to form a falling film and vaporize to start the reaction. At the same time, the collectio...

Embodiment 2

[0037] The operation is the same as in Example 1, and the use of the solvent is the same as in Example 1, replacing methyl 1,6-hexamethylene dicarbamate with ethyl 1,6-hexamethylene dicarbamate, and the concentration of the reaction raw material solution is 15g / 100g (mixed solvent), the reaction liquid flow rate is 115g / h, the inner wall temperature of the evaporator is controlled at 220-230°C, and the system pressure is stable at 0.45-0.6MPa. The rest of the operating conditions remain unchanged.

[0038] The average flow rate of fractional components at the top of the evaporator is shown in Table 3:

[0039] Table 3. Average Flow Rates of Evaporator Top Fraction Components

[0040]

[0041] The average flow rate of the material produced at the bottom of the evaporator is shown in Table 4:

[0042] Table 4. Average flow rate of materials produced at the bottom of the evaporator

[0043]

[0044] The yield of 1,6-hexamethylene diisocyanate was 97.2%, and no trimer pr...

Embodiment 3

[0046] The operation is the same as in Example 1, replacing methyl 1,6-hexamethylene dicarbamate with ethyl 1,6-hexamethylene dicarbamate, and replacing the solvent with N,N-diethylaniline and toluene according to Mixture with a weight ratio of 3:2. The concentration of the reaction raw material liquid is 15g / 100g (mixed solvent), and the flow rate of the reaction liquid is 115g / h. The inner wall temperature of the evaporator is controlled at 220-230°C, and the system pressure is stabilized at 0.20-0.3MPa. The rest of the operating conditions remain unchanged.

[0047] The average flow rate of the top fraction of the evaporator is shown in Table 5:

[0048] Table 5. Average Flow Rates of Evaporator Top Fraction Components

[0049]

[0050] The average flow rate of the extracted material at the bottom of the evaporator is shown in Table 6:

[0051] Table 6. Average flow rate of materials produced at the bottom of the evaporator

[0052]

[0053] The yield of 1,6-hexa...

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Abstract

The invention relates to a method for continuously preparing 1, 6-hexamethylene diisocyanate. Solution dissolved with hexamethylene diurethane is continuously pumped into a scraper falling film evaporator to form a falling film. The thermal cracking reaction is started. The inner wall temperature of the evaporator is controlled at 220 to 245 DEG C, and the reaction pressure is stabilized at 0.2-0.6MPa. Alcohol generated during the reaction together with little solvent evaporates from the top of the evaporator. The 1, 6-hexamethylene diisocyanate together with most of the solvent are produced from the bottom of the evaporator, and the yield is larger than 90 percent.

Description

field of invention [0001] The invention relates to a method for continuously preparing 1,6-hexamethylene diisocyanate. Background technique [0002] 1,6-Hexamethylene diisocyanate (HDI) is currently the aliphatic isocyanate with the largest demand in the polyurethane industry, and has become a Phenyl isocyanate (PAPI) is the most demanded isocyanate variety, mainly used in the production of high-grade polyurethane coatings, elastomers, adhesives, textile finishing agents, etc. The two isocyanate groups of HDI are similar in activity, and the derived polyurethane has the characteristics of low density, high strength, simple processing and molding, non-toxic and harmless, good thermal insulation performance, and better flame retardant and heat resistance than other types of plastics. Compared with aromatic isocyanates such as MDI, TDI and PAPI, the unique saturation of HDI-derived polyurethane has the advantages of non-yellowing, color retention, gloss retention, chalking res...

Claims

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Application Information

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IPC IPC(8): C07C265/14C07C263/04B01J10/02
Inventor 王越王公应刘良明王庆印姚洁胡晓佳李建国
Owner CHENGDU ORGANIC CHEM CO LTD CHINESE ACAD OF SCI
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