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Closed isocyanate curing agent, preparation method thereof and single-component coating

A technology of blocked isocyanate and blocked isocyanate, applied in the field of coatings, can solve the problems affecting the water resistance and chemical resistance of the paint film, the limited cross-linking density of the paint film, and the insufficient cross-linking density of the paint film. Improved water and chemical resistance, easy-to-achieve results

Inactive Publication Date: 2019-11-22
湖南湘江关西涂料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the cross-linking density of the paint film obtained by the blocked isocyanate curing agent on the market is not high enough when the varnish is cured, which affects the water resistance and chemical resistance of the paint film.
For example, a compound blocking agent of pyrazole derivative compound and active methylene compound is used to NCO block polyisocyanate, and the obtained blocked polyisocyanate has good storage stability, but it has limited effect on improving the crosslinking density of coating film.
Another blocked polyisocyanate that uses a mixture of malonate and triazole to block polyisocyanates can be used as a crosslinking agent for polyurethane baking varnishes to prevent crystallization in solvents and improve the heat yellowing performance of blocked polyisocyanates , however, it is also very limited to increase the crosslink density of the coating film

Method used

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  • Closed isocyanate curing agent, preparation method thereof and single-component coating
  • Closed isocyanate curing agent, preparation method thereof and single-component coating
  • Closed isocyanate curing agent, preparation method thereof and single-component coating

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preparation example Construction

[0053] Another embodiment of the present invention is to provide a method for preparing the above-mentioned blocked isocyanate curing agent, which includes the following steps S1-S3.

[0054] S1. Mixing the chain extender and the polyisocyanate trimer to extend the chain to obtain a prepolymer.

[0055] Wherein, the polyisocyanate trimer is selected from at least one of isophorone diisocyanate trimer, hexamethylene diisocyanate trimer and toluene diisocyanate trimer, and the chain extender is selected from At least one of polyfunctional compounds containing hydroxyl and / or amino groups and water, the polyfunctional compound having an alkyl group with 2 to 12 carbon atoms.

[0056] In one embodiment, water or a diol chain extender with 2-12 carbon atoms is used, and the temperature for chain extension is 40°C-90°C.

[0057] In one embodiment, diamine or alcoholamine having 2-12 carbon atoms is used as the chain extender, and the temperature for chain extension is 5°C-10°C.

...

Embodiment 1

[0091] (1) Install a reflux condenser, a thermocouple, a thermometer, and a nitrogen tube on a four-necked round-bottomed flask, and add 50% cosolvent (a mixed cosolvent composed of trimethylbenzene and PMA), IPDI trimer , blowing in nitrogen at the same time, stirring and dispersing for 15min, then raising the temperature to 80°C, stopping blowing in nitrogen, adding H 2 O and 30% co-solvent were reacted for 2 hours to obtain a urea-based prepolymer.

[0092] (2) After the reaction is completed, cool down to 30°C, add 3,5-dimethylpyrazole, 20% co-solvent for capping reaction, the reaction temperature is 60°C, and the capping time is 1h, until NCO≤0.1% is measured , end capping, stop the reaction.

[0093] (3) Detect and adjust the solid content of the mixture obtained in step (2) to 85%, add diatomaceous earth to filter and discharge, and obtain a blocked isocyanate curing agent with a crosslinked structure.

Embodiment 2

[0095] (1) Install a reflux condenser, a thermocouple, a thermometer, and a nitrogen tube on the four-necked round-bottomed flask, add 50% cosolvent and HDI trimer under stirring, blow into nitrogen simultaneously, stir and disperse for 15min, and then Raise the temperature to 80° C., stop blowing nitrogen, add ethylene glycol and 30% co-solvent, and react for 2 hours to obtain a urethane prepolymer.

[0096] (2) After the reaction is completed, cool down to 30°C, add 1,2,4-triazole and 20% co-solvent (trimethylbenzene / PMA) for capping reaction, the reaction temperature is 80°C, and the capping time is 0.5h, until When NCO≤0.1% is measured, the capping is completed and the reaction is stopped.

[0097] (3) Detect the solid content, adjust the solid content to 75%, add diatomaceous earth to filter the material, and obtain a blocked isocyanate curing agent with a cross-linked structure.

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Abstract

The invention relates to a closed isocyanate curing agent, a preparation method thereof and a single-component coating. The closed isocyanate curing agent is prepared from the following raw materials:a polyisocyanate trimer, a chain extender, a sealing agent and a cosolvent, wherein the polyisocyanate trimer is selected from at least one of an isophorone diisocyanate trimer, a hexamethylene diisocyanate trimer and a toluene diisocynate trimer, the chain extender is selected from at least one of a polyfunctional compound containing hydroxyl and / or amino and water, and the polyfunctional compound has 2-12 carbon atoms. The closed isocyanate curing agent has a cross-linked structure with multiple cross-linking sites, and a closed isocyanate curing agent trimer can be subjected to multi-sitecross-linking with amino resin, acrylic resin and the like in a varnish coating formula, so that the cross-linking density of a coating film can be improved.

Description

technical field [0001] The invention relates to the technical field of coatings, in particular to a blocked isocyanate curing agent, a preparation method thereof, and a one-component coating. Background technique [0002] Blocked isocyanate curing agent is a kind of auxiliary curing resin that does not cure at room temperature and is stable in storage. Due to its excellent stability, it is widely used in 1K (one-component) clearcoat coatings of automotive coatings. [0003] However, the cross-linking density of the paint film obtained by the blocked isocyanate curing agent on the market when the varnish is cured is not high enough, which affects the water resistance and chemical resistance of the paint film. For example, a compound blocking agent of pyrazole derivative compound and active methylene compound is used to NCO block polyisocyanate, and the obtained blocked polyisocyanate has good storage stability, but it has limited effect on improving the crosslinking density o...

Claims

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Application Information

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IPC IPC(8): C08G18/80C08G18/79C08G18/30C08G18/32
CPCC08G18/302C08G18/3206C08G18/3228C08G18/3271C08G18/792C08G18/8038
Inventor 喻佳杨鹏飞张杰胡启明黄鹂
Owner 湖南湘江关西涂料有限公司
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