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Separating method for isocyanate monomer of urethane curing agent

A polyurethane curing agent and isocyanate technology, which is applied in the field of separation and purification of high-viscosity heat-sensitive, easy-to-cure polymers, can solve the problems of low solid content of polyurethane curing agent, high isocyanate content, low isocyanate content, etc. Capacitive, reduce the effect of side reactions

Inactive Publication Date: 2005-02-23
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The present invention aims at the shortcomings of the polyurethane curing agent obtained by the existing separation method, such as low solid content, high isocyanate content, high viscosity, poor fluidity, etc., and provides an efficient and economical separation method for isocyanate in the polyurethane curing agent, and the obtained curing agent High solid content, low isocyanate content, low viscosity

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Using toluene diisocyanate (TDI) and trimethylolpropane (TMP) with an NCO / OH equivalent ratio of 1.9, adding butyl acetate as a solvent, and reacting at 55°C for 2 hours to synthesize a curing agent with a solid content of 50% 3Kg, a polyurethane curing agent with a free TDI content of 3.1%. In the solidifying agent of synthesis, add the phosphoric acid of 1 / 10,000 that is 0.3g and 8% that is 240g methyl benzoate, carry out primary separation at 90 ℃, 2000Pa in the thin-film evaporator described in the second step with this curing agent , carry out secondary separation at 120°C and 10Pa, then pump it into the dilute container, configure it as a 75% solvent at 60°C, and obtain the product with a free TDI mass content of 0.42% and an NCO content of 12.7% .

Embodiment 2

[0031] Adopting toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) is the mixture of 1: 1 by mass ratio and the NCO / OH equivalent ratio of trimethylolpropane (TMp) is the proportioning of 2.3, adds butyl acetate The mixture of ester and xylene is used as a solvent, reacted at 55 ℃ for 4 hours to synthesize 3Kg of curing agent with a solid content of 50%, and a polyurethane curing agent with a free diisocyanate content of 8.5%. In the solidifying agent of synthesis, add two ten thousandths that is the phosphoric acid of 0.6g and 10% that is 300g methyl benzoate and 10% that is 300g butyl benzoate, in the thin film evaporator described in the second step, this curing agent Carry out primary separation at 90°C and 2000Pa, and carry out secondary separation at 120°C and 10Pa, then pump it into the dilute container, configure it as a 75% solvent at 60°C, and obtain the product with the quality of free TDI The content of NCO is 0.42%, and the content of NCO is 12.7%.

Embodiment 3

[0033] Adopt 190mol of hexamethylene diisocyanate (HDI) and 100mol of polypentylene glycol (relative molecular weight is 1000, hydroxyl content is 3.3%) to add in the reactor, add dehydration cyclohexanone as solvent and react at 120 ℃ for 6 hours, Synthetic solid content is 50%, and free TDI content is the polyurethane curing agent of 8.9%, then add the phosphoric acid of 200g and 15kg S-200 solvent, this curing agent is in the thin film evaporator described in the second step at 180 ℃, 30000Pa Carry out primary distillation, carry out secondary distillation under the situation of 210 ℃, 600Pa, carry out tertiary distillation under the situation of 240 ℃, 400Pa, then pump into the dilute container, configure 80% solvent at 140 ℃, obtain Product, its free TDI mass content is 0.15%, and NCO content is 7.9%.

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Abstract

A method for separating isocyanic ester from polyurethane-curing agent includes; adding acid 0.01 - 0.5% as reaction inhibitor, adding distillation agent 8 -60%, carrying out three-stage separation in an internally or externally cooling membrane distiller, pumping remains separated after second or third stage to pass them into a diluting container with solvent in, heating solvent up to 80 - 140deg.C, and stirring solvent with solid remains 35 - 85% to obtain curing agent with high solid content, low isocyanic ester content, and low viscosity.

Description

technical field [0001] The invention relates to the separation and purification of high-viscosity heat-sensitive easily curable polymers, and is especially suitable for the separation of residual free and toxic isocyanate monomers in polyurethane curing agents for coatings or adhesives. Background technique [0002] Polyurethane coating film has beautiful appearance, high hardness, corrosion resistance and chemical resistance, and is one of the coating varieties with the best comprehensive performance. Polyurethane adhesives also have similar characteristics and have high bonding strength. According to modern environmental protection requirements, polyurethane coatings or adhesives must solve two technical problems. One is to increase the solid content and minimize the solvent content. The second is to reduce the free di(poly)isocyanate content in the polyurethane curing agent, that is, to develop a non-toxic curing agent. [0003] At present, my c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J11/02
Inventor 胡孝勇黄洪张心亚陈焕钦
Owner SOUTH CHINA UNIV OF TECH
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