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Method for preparing polyurethane curing agent

A technology of polyurethane curing agent and curing agent, which is applied in the direction of chemical instruments and methods, polyurea/polyurethane coating, urea derivative preparation, etc. It can solve the problems of adverse effects of end use and improvement, difficulty in volatilization of entraining agent, difficulty in recycling, etc. , to achieve the effects of reducing operating costs and investment costs, high gas-liquid mass transfer efficiency, and easy replacement of material systems

Active Publication Date: 2013-07-17
WANHUA CHEM GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the use of this entrainer will inevitably increase the cost of the product; at the same time, the entrainer contains free monomers, which makes it difficult to recycle; in addition, there will be more entrainer residues in the product
Due to the high boiling point of the entrainer, it is difficult to volatilize the entrainer during actual use, which will have a negative impact on the end use of the product and increase the requirements for equipment. Three-stage separation, long process and low production efficiency

Method used

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  • Method for preparing polyurethane curing agent
  • Method for preparing polyurethane curing agent

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] Using the above-mentioned process steps, add 100kg of hexamethylene diisocyanate (HDI) in the normal pressure reactor, stir and heat up after nitrogen replacement, add catalyst 0.3kg phosphoric acid bis(2-ethylhexyl) after mixing, 2kg distilled water passes through The nozzle is sprayed into the reaction kettle, and the addition is completed in 2 hours. After spraying, the temperature is raised to 130°C and kept for 2 hours. The reaction liquid enters the thin film evaporator for separation. The separation temperature is 150°C and the separation pressure is 300Pa. The obtained separated heavy component enters the high-speed rotary bed at a speed of 15m / s, and the secondary separation is carried out under the condition of setting the rotational speed of the rotary bed at 300rpm. After separation, the HDI biuret product is obtained, and its free HDI mass content is 0.38%, and the NCO content is 0.38%. It is 21.7%, viscosity 9360cp.

Embodiment 2

[0055] In a reaction kettle with a thermometer, agitator, and reflux condenser, mix HDI and IPDI at a mass ratio of 1:1, the molar ratio is (5.9:4.5), replace with nitrogen, and heat the reactant to 55°C , based on the quality of HDI and IPDI, 400ppm tri-n-butylphosphine was added to keep the reaction temperature not exceeding 65°C, and the NCO% of the mixed reaction solution was 33.9%. After 15 hours of reaction, 500ppm phosphoric acid was added to terminate the reaction. The primary separation temperature is 120°C and the separation pressure is 1000Pa. The obtained separated heavy component enters the high-speed rotary bed at a speed of 10m / s, and the secondary separation is carried out at the speed of the rotary bed at 400rpm. It is an oligomer of 8630cp / 25°C, the NCO content is 19.8%, and the residual monomer content is 0.18% HDI and 0.14% IPDI respectively. Then pump it into the dilute container, configure it as a 50% solvent at 100°C, and obtain the product.

Embodiment 3

[0057] In a reaction kettle with a thermometer, agitator, and reflux condenser, add HDI, replace with nitrogen, heat the reactant to 55°C, and gradually add 700ppm quaternary ammonium salt catalyst DABCO based on the quality of HDI The reaction temperature does not exceed 70°C, the NCO% of the mixed reaction liquid is 38.1%, and 600ppm benzoyl chloride is added to terminate the reaction. The prepared HDI trimer reaction liquid is subjected to primary separation at 130°C and 1000Pa through a primary thin film evaporator , the free monomer content of the obtained isolated heavy fraction was 8.1%, and the viscosity was 947cp / 25°C. Enter the high-speed rotating bed at a speed of 20m / s, set the temperature of the rotating bed at 150°C, the pressure at 30Pa, and the rotation speed at 200rpm for secondary separation, and then put it into the product storage tank to obtain the product. The free HDI mass content 0.2%.

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Abstract

The invention discloses a method for preparing a polyurethane curing agent. The method comprises the following steps of: firstly, evaporating a curing agent obtained by polymerizing an isocyanate monomer through an external cold type film evaporator to remove part of free isocyanate monomer; and secondly, separating heavy components separated by the external cold type film evaporator through a high-speed rotary bed to obtain a product with lower free monomer content, wherein the content of the free isocyanate monomer is 0.05-0.6 percent by weight. The method disclosed by the invention has theadvantages of small size of equipment, high separation speed, high quality of products, high recovery rate of the monomer, capability of meeting the requirements of environmental friendliness, relatively low requirement on filed and little investment. According to the method, the content of the free isocyanate monomer in the polyurethane curing agent is reduced without remarkably increasing the relative molecular weight and molecular weight distribution of polyisocyanates and the downstream application is facilitated.

Description

technical field [0001] The present invention relates to a process for the preparation of polyurethane curing agents, and more particularly to the separation of free isocyanate monomer method. Background technique [0002] As we all know, polyurethane curing agent is an important factor to determine the performance of polyurethane coating film. It directly affects or determines the dryness, physical and mechanical properties, decoration, medium resistance, durability and weather resistance of the coating film. The technology and products of curing agent The quality level represents the industrial level of polyurethane coatings. [0003] At present, my country's polyurethane curing agent has a single variety, low solid content, high residual free isocyanate monomer content, and high toxicity. Methods to reduce residual monomers in polyurethane curing agents include chemical reaction, solvent extraction, supercritical extraction, and molecular sieve adsorption. method and vacu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G18/02C08G18/00C07C275/62C07C273/18C07D251/30C09D175/04C09D7/12
Inventor 李建峰尚永华华卫琦丁建生王玉启王海影孙立冬唐义权隋宝华
Owner WANHUA CHEM GRP CO LTD
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