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Dissolvant type polyurethane curing agent synthetic method for producing low free toluene diisocyanate content

A technology of toluene diisocyanate and polyurethane curing agent, applied in the direction of polyurea/polyurethane coatings, coatings, etc., can solve the problems of high content of toluene diisocyanate, narrowing difference in reactivity and high reaction temperature, and achieve low content of free toluene diisocyanate. , low production cost, good flexibility

Active Publication Date: 2009-06-17
GUANGDONG HUARUN PAINT CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0020] However, the current synthesis method of polyurethane curing agent, especially the post-trimerization method, adopts a relatively high reaction temperature, usually 50-90°C. At this temperature, the reactivity of the NCO groups at different positions on the benzene ring The difference narrows and closes, reducing the selectivity of the reaction, resulting in high levels of free toluene diisocyanate

Method used

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  • Dissolvant type polyurethane curing agent synthetic method for producing low free toluene diisocyanate content
  • Dissolvant type polyurethane curing agent synthetic method for producing low free toluene diisocyanate content
  • Dissolvant type polyurethane curing agent synthetic method for producing low free toluene diisocyanate content

Examples

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Effect test

no. 1 example

[0052] In the reactor that stirring, nitrogen and thermometer are installed, drop into 522 grams of toluene diisocyanate and 227 grams of butyl acetate as solvent, start stirring, and start to heat up. When the material temperature of the mixture in the reactor reached 50° C., 134 grams of trimethylolpropane was started to be added dropwise. The molar ratio of NCO / OH in toluene diisocyanate and trimethylolpropane is 2:1. The dropwise addition time is about 1 hour. After the dropwise addition of trimethylolpropane, keep the temperature at 50°C. During the heat preservation period, take a sample from the reactor every hour to detect the NCO content until the NCO content is stable, and the NCO content is 14.3%. During the above dropping process, turn on the freezer and set the outlet temperature of the chilled water to 15°C. When the outlet water temperature reaches 15°C and stabilizes, it is ready for use. When the NCO content is stable, stop heating immediately, remove the he...

no. 2 example

[0055] Same as the first embodiment, only the amount of trimethylolpropane triacetoacetate is replaced by 16 grams. Trimethylolpropane triacetoacetate accounted for 2.38% by weight of non-volatile matter.

[0056] The viscosity of the polyurethane curing agent product is 1500mPa.s, the NCO content is 13.93%, and the color is 20#. It is measured by Pt-Co colorimetry, and the free toluene diisocyanate content is 0.42%, and the non-volatile matter is 73.7%.

no. 3 example

[0058] Same as the first embodiment, only the temperature of the second low-temperature reaction is set to 25°C. Product viscosity is 2100mPa.s, NCO content is 13.42%, color is 20#, measured by Pt-Co colorimetric method, free TDI content is 0.46%, non-volatile matter is 73.9%.

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Abstract

The invention relates to a synthesis method for preparing a solvent based polyurethane curing agent with low content of dissociated toluene di-isocyanate, which is characterized in that the reaction undergoes in two stages: stage one, the toluene di-isocyanate and polylol react in the solvent, the reaction degree is monitored by sampling and detecting the content of NCO from the reacted mixture during the reaction process; when the content of NCO is stable, the reaction reaches the endpoint of stage one; stage two, acetylacetic ester is added to the reacted mixture; after the reaction goes on, the reaction degree is monitored by sampling and detecting the content of NCO from the reacted mixture during the reaction process; when the content of NCO is stable again, the reaction reaches the endpoint of stage two, which is also the endpoint of the overall reaction; wherein, the reaction of the stage two is conducted at low temperature. The synthesis method is characterized by small investment, low content of dissociated toluene di-isocyanate monomer, low viscosity, good flexibility and stable product performance.

Description

technical field [0001] The invention relates to a synthesis method for producing a solvent-based polyurethane curing agent with low content of free toluene diisocyanate, which is especially suitable for environment-friendly polyurethane coatings. Background technique [0002] Polyurethane coatings are widely used in furniture and home decoration. One of its components is based on hydroxyl-containing substances such as alkyd resins, polyester resins and acrylic resins, and the other component is substances containing NCO groups, also known as polyurethane curing agents. The development of polyurethane coatings in China is very rapid. It is the largest variety of solvent-based coatings and occupies a dominant position in furniture coatings. The paint film of polyurethane coating has the advantages of high hardness, good toughness, strong chemical resistance and fast drying. [0003] The figure below is a schematic diagram of polyurethane adduct curing agent. [0004] [...

Claims

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Application Information

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IPC IPC(8): C08G18/30C08G18/34C08G18/78C09D175/04
Inventor 曾光明孔淑香李景宏刘晓燕马红肖
Owner GUANGDONG HUARUN PAINT CO LTD
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