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Method for making amine-modified epoxy resin and cationic electrodeposition coating composition

A cationic electrodeposition, epoxy resin technology, applied in the direction of epoxy resin coating, electrophoretic coating, coating, etc., can solve the problems such as prone to pinholes, and achieve the effect of excellent appearance, excellent appearance and high dispersion ability

Inactive Publication Date: 2007-01-10
NIPPON PAINT CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the applied voltage is increased to obtain a thicker electrodeposited coating film, pinholes are prone to occur

Method used

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  • Method for making amine-modified epoxy resin and cationic electrodeposition coating composition
  • Method for making amine-modified epoxy resin and cationic electrodeposition coating composition
  • Method for making amine-modified epoxy resin and cationic electrodeposition coating composition

Examples

Experimental program
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preparation example Construction

[0142] Preparation of lead-free cationic electrodeposition paint composition (first embodiment)

[0143] The lead-free cationic electrodeposition coating composition of the present invention is prepared by dispersing the above-mentioned amine-modified epoxy resin, blocked isocyanate curing agent, pigment dispersion paste and catalyst in an aqueous medium. In addition, a neutralizing acid may be included in the aqueous medium to neutralize the cationic epoxy resin and improve the dispersibility of the binder resin emulsion. Examples of acids for neutralization include inorganic acids or organic acids such as hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid, lactic acid, sulfamic acid, acetylglycine and the like. The aqueous medium used here is water or a mixture of water and an organic solvent. The water preferably used is deionized water. Examples of organic solvents used include hydrocarbons (such as xylene or toluene), alcohols (such as methanol, n...

preparation Embodiment 1

[0184] Production Example 1 (1st and 2nd Embodiments)

[0185] Preparation of Blocked Polyisocyanate Curing Agents

[0186]1250 parts of diphenylmethane diisocyanate and 266.4 parts of methyl isobutyl ketone (hereinafter referred to as MIBK) were placed in a reaction kettle, and 2.5 parts of dibutyltin dilaurate were added thereto after heating to 80°C. A solution obtained by dissolving 226 parts of ε-caprolactam in 944 parts of butyl cellosolve was dropped thereto over 2 hours at 80°C. It was reacted at 100°C for 4 hours, and the absorption based on the isocyanate group was confirmed to disappear by infrared spectrum measurement, and allowed to cool. 336.1 parts of MIBK were added to obtain a blocked isocyanate curing agent with a glass transition temperature of 8°C.

preparation Embodiment 2

[0188] Preparation of amine-modified epoxy resin (first embodiment)

[0189] 35 parts of 2,4- / 2,6-toluene diisocyanate (weight ratio=8 / 2), 94 parts of MIBK and 0.5 part of dibutyltin dilaurate were placed in a device equipped with agitator, condenser, nitrogen conduit, thermometer and dropping funnel in the flask. While stirring the above reaction mixture, 7 parts of methanol were added thereto. Starting from room temperature, the reaction mixture was heated to 60°C due to exotherm, the reaction was maintained for 30 minutes, and 12 parts of ethylene glycol mono-2-ethylhexyl ether were added dropwise from the dropping funnel. In addition, 33 parts of bisphenol A-propylene oxide 5 mol adduct were added. The reaction is mainly carried out in the temperature range of 60-65 °C until the absorption based on the isocyanate group disappears in the infrared spectroscopic measurement. Next, 383 parts of an epoxy resin having an epoxy equivalent of 188 synthesized from bisphenol A an...

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Abstract

The present invention provides a cationic electrodeposition coating composition having good appearance of coated film and high throwing power, and a method for making an amine-modified epoxy resin used for the cationic electrodeposition coating composition. The present invention relates to a method for making an amine-modified epoxy resin comprised in a cationic electrodeposition coating composition comprising the steps of: providing a half blocked isocyanate by reaction of an isocyanate compound with a blocking agent, preparing a blocked prepolymer by reaction of the half blocked isocyanate with a polyol, forming an epoxy resin containing oxazolidone ring by reaction of the blocked prepolymer with a diglycidyl ether type epoxy resin, chain-extending the epoxy resin containing oxazolidone ring with at least saturated or non-saturated hydrocarbon group containing dicarboxylic acid, and modifying the chain-extended epoxy resin with an amine.

Description

technical field [0001] The present invention relates to a cationic electrodeposition coating composition with good coating appearance and high dispersibility, and a method for preparing amine-modified epoxy resin used in the cationic electrodeposition coating composition. Background technique [0002] By electrodeposition coating using the cationic electrodeposition coating composition, a material to be coated having a complicated structure can be coated finely and can be applied automatically and continuously. Accordingly, cationic electrodeposition coatings have been widely used industrially as primers for large-scale materials to be coated with complex structures, such as automobile bodies. Cationic electrodeposition coating is performed by impregnating a material to be coated as a cathode with a cationic electrodeposition coating composition, and applying a voltage thereto. [0003] The coating film is deposited by electrochemical reaction in t...

Claims

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Application Information

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IPC IPC(8): C09D163/10C09D5/44C09D7/12
Inventor 白川信介印藤俊明三原康央北村直孝
Owner NIPPON PAINT CO LTD
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