Preparation method of blocked isocyanate for improving film-forming performance of cathodic electrophoretic coating

A technology for blocking isocyanate and cathodic electrophoretic coatings, applied in electrophoretic coatings, epoxy resin coatings, coatings, etc., can solve the problems of high heating loss, narrow deblocking range, low crosslinking density, etc. The effect of easy reaction process and simple operation

Active Publication Date: 2020-12-22
HUNAN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, especially for the ubiquitous unblocking temperature of existing blocked isocyanates, high heat loss, narrow unblocking range, low utilization rate of -NCO, cathodic electrophoretic coatings Poor thermal fluidity, low throwing power, low cross-linking density, and the new automotive coating industry require the thickness of the primer to be reduced, the flatness of the coating film to be improved, and the corrosion resistance to be enhanced. It provides a low-cost, easy-to-operate Preparation method of blocked isocyanate for improving film-forming properties of cathodic electrophoretic coatings with easy process control

Method used

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  • Preparation method of blocked isocyanate for improving film-forming performance of cathodic electrophoretic coating
  • Preparation method of blocked isocyanate for improving film-forming performance of cathodic electrophoretic coating
  • Preparation method of blocked isocyanate for improving film-forming performance of cathodic electrophoretic coating

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Effect test

Embodiment 1

[0058] The preparation method of the blocked isocyanate that improves the film-forming performance of cathodic electrophoretic coating of the present embodiment comprises the following specific steps:

[0059] (1) Preparation of isocyanate trimer: Add 100g of isophorone diisocyanate to a 500mL four-neck flask equipped with a condensing reflux tube, agitator, dropping funnel, thermometer, and nitrogen protection device, and add 0.4g of organic bismuth DY -20 and 44.98g methyl ethyl ketone, react at a constant temperature of 105°C, measure the -NCO group content regularly, until the -NCO content drops to a predetermined value (the "theoretical value" is half of the -NCO reacted), then lower the reaction temperature to room temperature , to prepare a mixed isocyanate with isocyanate trimer and monomer structure;

[0060] (2) Preparation of branched polyisocyanate crosslinking agent: control the R value of the prepolymerization reaction to 2.05, dissolve 20.20 g of trihydroxypropa...

Embodiment 2

[0065] The preparation method of the blocked isocyanate that is used to improve the film-forming performance of cathodic electrophoretic coating of the present embodiment comprises the following concrete steps:

[0066] (1) Preparation of isocyanate trimer: Add 100g of 4,4-diphenylmethane diisocyanate into a 500mL four-necked flask equipped with a condensing reflux tube, stirrer, dropping funnel, thermometer, and nitrogen protection device, and add 0.4 g of organic bismuth DY-20 and 44.98g of methyl ethyl ketone were reacted at a constant temperature of 105°C, and the -NCO group content was measured regularly until the -NCO content dropped to a predetermined value. Mixed isocyanates of monomer structure;

[0067] (2) Preparation of branched polyisocyanate crosslinking agent: control the R value of the prepolymerization reaction to 2.05, dissolve 20.20 g of trihydroxypropane in methyl ethyl ketone, and add it dropwise to the system obtained in step (1) within 1 hour Then heat ...

Embodiment 3

[0072] The preparation method of the blocked isocyanate that is used to improve the film-forming performance of cathodic electrophoretic coating of the present embodiment comprises the following specific steps:

[0073] (1) Preparation of isocyanate trimer: Add 100g of isophorone diisocyanate to a 500mL four-neck flask equipped with a condensing reflux tube, agitator, dropping funnel, thermometer, and nitrogen protection device, and add 0.4g of organic bismuth DY -20 and 44.98g methyl ethyl ketone, 105 ℃ constant temperature stirring reaction, regularly measure -NCO group content, until the -NCO content drops to a predetermined value, the reaction temperature is lowered to room temperature, and the isocyanate trimer and monomer structure are prepared. Mixed isocyanates;

[0074] (2) Preparation of branched polyisocyanate crosslinking agent: control the R value of the prepolymerization reaction to 2.05, dissolve 20.20 g of trihydroxypropane in methyl ethyl ketone, and add it dr...

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Abstract

The invention discloses a preparation method of blocked isocyanate used for improving film forming performance of a cathode electrophoresis coating. The method comprises the following steps: (1) preparing an isocyanate tripolymer by using an organic compound as a catalyst under protection of a nitrogen gas; (2) performing chain extension by a polyhydroxy monomer to prepare an isocyanate-terminatedpolyisocyanate prepolymer, and blocking the prepolymer by using a composite blocking agent to prepare a branched polyisocyanate cross-linking agent; and (3) in the branching system, adding diisocyanate, performing chain extension by a polyester polyol to prepare an isocyanate-terminated diisocyanate prepolymer, performing hydrophilic modification on the isocyanate-terminated diisocyanate prepolymer by an alkynol surfactant, and blocking the prepolymer by using a composite blocking agent to obtain the blocked polyisocyanate cross-linking agent. The preparation method for the blocked isocyanatedisclosed by the invention is simple, the reaction process is easy to control, the blocked isocyanate has low deblocking temperature as a curing agent, and the prepared electrophoresis coating film has low heating loss, good thermal fluidity, high flatness, a high crosslinking density, and excellent corrosion resistance.

Description

technical field [0001] The invention relates to the preparation of an isocyanate curing agent and the field of water-based coatings, in particular to a method for preparing a blocked isocyanate for improving the film-forming performance of cathodic electrophoretic coatings. Background technique [0002] As a new type of environmentally friendly water-based coating, electrophoretic coatings have the characteristics of environmental protection, energy saving, high efficiency, and high yield. In the history of the world's automobile industry for more than 100 years, electrophoretic coatings have been used to replace spraying and dipping primers for automobile bodies ( Commonly known as the bottoming process) has been more than half a century. With the rapid development of the automobile industry, the technical development of cathodic electrophoretic coatings is changing with each passing day, and new coating development technologies and coating technologies emerge in endlessly....

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G18/80C08G18/42C08G18/02C09D163/00C09D5/44
CPCC08G18/022C08G18/4277C08G18/8025C08G18/8029C09D5/4453C09D163/00C08G2115/02
Inventor 刘娅莉袁松张旭东符余香黄鹂李健刘美凤
Owner HUNAN UNIV
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