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Process for preparing low free toluene diisocyanate curing agent

A technology of toluene diisocyanate and polyisocyanate, applied in the field of polyurethane curing agent preparation, can solve the problems of large loss of acetonitrile, dark color of curing agent, unsuitable for industrial production, etc.

Inactive Publication Date: 2005-01-26
ZHUHAI FEIYANG NOVEL MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] A kind of extraction method is mentioned in U.S. Patent US.3883577, and it has provided and used acetonitrile as action medium, and this solvent has good affinity to the polyisocyanate of high molecular weight, and extractant aliphatic hydrocarbon is only partially miscible, and this The boiling point of this solvent is low, and it is easy to remove by distillation without causing side reactions, but the color of the curing agent obtained by this method is darker, and the loss of acetonitrile is relatively large, so it is not suitable for industrialized production

Method used

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  • Process for preparing low free toluene diisocyanate curing agent
  • Process for preparing low free toluene diisocyanate curing agent
  • Process for preparing low free toluene diisocyanate curing agent

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Add 522g of toluene diisocyanate into a reactor equipped with a stirring device, a feeding port, a thermometer and a dry nitrogen protection device, then add 165.9g of dimethyl carboxylate, and add it in 6 batches after raising the temperature to 50°C A mixture of 91 g of trimethylolpropane and 50.5 g of neopentyl glycol was maintained at 70°C for 3.5 hours at intervals of 30 minutes.

[0027] When the weight percentage of free NCO groups is 15-16%, add polyisocyanate trimer catalyst lithium phenate 0.17g, react at 65°C for 3 hours, take a sample every 30 minutes to detect the free NCO Percentage by weight, the reaction continues until the NCO content drops to 14±0.5%, and then 0.08 g of polyisocyanate trimer inhibitor phosphoric acid is added to terminate the reaction.

[0028] Add 4147g of petroleum ether into the reactor in 5 times, after stirring for 15 minutes each time, let it stand for 5 minutes, pump the petroleum ether into the distillation still under vacuum, ...

Embodiment 2

[0039] Add 783g of toluene diisocyanate into a reactor equipped with a stirring device, a feeding port, a thermometer and a dry nitrogen protection device, then add 231.1g of γ-butyrolactone, and add 91g in 6 batches after raising the temperature to 50°C A mixture of trimethylolpropane and 50.5 g of neopentyl glycol, at 30 minute intervals, was then incubated at 70°C for 3.5 hours.

[0040] When measuring the weight percentage of free NCO groups to be 15-16%, add polyisocyanate trimer catalyst tin octoate 0.58g (0.05%), after reacting at 65°C for 3 hours, take a sample every 30 minutes Detect the weight percentage of free NCO, and the reaction continues until the NCO content drops to 14 ± 0.5%, and then 0.27 g of polyisocyanate trimer polymerization inhibitor benzoyl chloride is added to terminate the reaction.

[0041] Add 5778.1 g of cyclohexane into the reactor in 6 times, stir for 15 minutes each time, and then let stand for 5 minutes. Vacuumize the cyclohexane into the d...

Embodiment 3

[0052] Add 652.5g of toluene diisocyanate into a reactor equipped with a stirring device, a feeding port, a thermometer and a dry nitrogen protection device, then add 337g of dimethyl sulfoxide, and add 134g in 6 batches after raising the temperature to 50°C Trimethylolpropane, each interval is 30 minutes, and then incubated at 70°C for 3.0 hours.

[0053] When the weight percentage of free NCO groups is 15-16%, add polyisocyanate trimer catalyst lithium stearate 1.68g, react at 65°C for 2.5 hours, take a sample every 30 minutes The weight percentage of free NCO, the reaction continues until the NCO content drops to 14 ± 0.5%, after adding polyisocyanate trimer polymerization inhibitor diethylhexyl hydrogen phosphate 0.94g to terminate the reaction.

[0054] Add 5617.5 g of n-hexane into the reactor in 5 times, stir for 15 minutes each time, and let stand for 5 minutes. Vacuumize the n-hexane into the still, and separate the n-hexane from the free toluene diisocyanate through...

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Abstract

The preparation process of low free toluene diisocyanate as curing agent includes the following steps: reaction between toluene diisocyanate and polyol in the NCO / OH molar ratio 2-3 at 50-80 deg.c with reaction medium SO2, gamma-butrrolactone, dimethhyl sulfoxide, dimethyl carboxy diacid ester; adding polyisocyanate polymerizing catalyst when the content of NCO is 15-16 % for further reaction and adding polyisocyanate polymerizing inhibitor when the content of NCO is 14-15%; adding fatty hydrocarbon and / or cyclic fatty hydrocarbon as extracting agent for multiple extraction, eliminating the extracting agent through letting stand or distillation; and diluting and discharging pre-polymer. The present invention can prepare curing agent with low chroma, low visosity and high NCO content and no toluene diisocyanate monomer and other toxic matter.

Description

technical field [0001] The invention relates to a preparation method of a polyurethane curing agent. Background technique [0002] At present, the most commonly used polyurethane curing agent production method in China is to use trimethylolpropane and toluene diisocyanate to react to form a prepolymer. The schematic unit structure of the prepolymer is as follows: [0003] [0004] In the production process of the prepolymer, there is a large amount of unreacted toluene diisocyanate, namely TDI, which must be removed due to the high gas phase toxicity of toluene diisocyanate. With the establishment of environmental protection regulations in various countries and the enhancement of people's environmental awareness, the content of free toluene diisocyanate in curing agents in traditional solvent-based coatings is increasingly restricted. Therefore, the development of low free toluene diisocyanate curing agent has become one of the important directions in the development of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G18/10C08G18/32C08G18/76
Inventor 肖增钧卢亭枫
Owner ZHUHAI FEIYANG NOVEL MATERIALS
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