阅读说明：本技术 一种β-羟烷基酰胺固化剂的制备方法 (Preparation method of beta-hydroxyalkylamide curing agent ) 是由 刘旭亮 李振勇 周幸旺 寇成龙 赵萍蕊 于 2019-09-18 设计创作，主要内容包括：本发明公开了一种β-羟烷基酰胺固化剂的制备方法,包括以下制备步骤：(1)将己二酸二甲酯或己二酸二乙酯和二乙醇胺混合,加入催化剂,升温,减压蒸出易挥发组分,得到四羟乙基己二酰胺溶液,为产物A。反应方程式如下：(2)将产物A固化,破碎,烘干,得到白色粉末固体,即合格的四羟乙基己二酰胺(β-羟烷基酰胺)。利用本发明的方法制备的固化剂收率高,制备过程中无废水、废液和废固产生,绿色环保,且设备投入少,操作简单。(The invention discloses a preparation method of a beta-hydroxyalkylamide curing agent, which comprises the following preparation steps: (1) mixing dimethyl adipate or diethyl adipate and diethanol amine, adding a catalyst, heating, decompressing and evaporating volatile components to obtain a tetrahydroxyethyl adipamide solution, namely a product A. The reaction equation is as follows: (2) solidifying, crushing and drying the product A to obtain white powder solid, namely qualified tetrahydroxyethyl adipamide (beta-hydroxyalkylamide). The curing agent prepared by the method has high yield, no waste water, waste liquid and waste solid are generated in the preparation process, the method is green and environment-friendly, the equipment investment is low, and the operation is simple.)

1. The preparation method of the beta-hydroxyalkylamide curing agent is characterized by comprising the following preparation steps:

(1) mixing dimethyl adipate or diethyl adipate and diethanol amine, adding a catalyst, heating, decompressing and evaporating volatile components to obtain a tetrahydroxyethyl adipamide solution serving as a product A; the reaction formula is as follows:

(2) and solidifying, crushing and drying the product A to obtain white powder solid, namely the tetrahydroxyethyl adipamide curing agent.

2. The method of claim 1, wherein the molar ratio of diethanolamine to dimethyl adipate or diethyl adipate is 1.8-2.5.

3. The method of claim 1, wherein the molar ratio of diethanolamine to dimethyl adipate or diethyl adipate is 2.0-2.4.

4. The method for preparing a beta-hydroxyalkylamide curing agent according to claim 1, wherein the catalyst is any one or any combination of potassium methoxide, potassium ethoxide, potassium acetate, potassium benzoate, potassium adipate and potassium hydroxide.

5. The method for preparing a β -hydroxyalkylamide curing agent according to claim 1, wherein the weight percentage of the catalyst to the product a is 0.11 to 0.14%.

6. The method for preparing a beta-hydroxyalkylamide curing agent according to claim 1, wherein the reaction temperature in the step (1) is 65 to 85 ℃.

7. The method for preparing a beta-hydroxyalkylamide curing agent according to claim 1, wherein the curing time in the step (2) is 8 to 12 hours.

8. The method for preparing a beta-hydroxyalkylamide curing agent according to claim 1, wherein the drying temperature in the step (2) is 85 to 100 ℃.

Technical Field

The invention relates to the technical field of coatings, in particular to a preparation method of a beta-hydroxyalkylamide curing agent.

Background

The beta-hydroxyalkylamide is a substance with beta-hydroxyl of a polyhydroxyalkyl functional group, and the hydroxyl is in a beta position and can generate a crosslinking reaction with carboxyl in a resin molecule under the influence of an N atom, so the beta-hydroxyalkylamide can be used as a curing agent of a polyester resin powder coating. As a novel powder coating curing agent, the beta-hydroxyalkylamide has the advantages of low toxicity, no stimulation, no mutagenesis and the like, has good application performances of weather resistance, heat resistance, corrosion resistance and the like, and has good leveling property and excellent impact resistance. And are therefore of great interest to researchers in the field of powder coatings.

At present, the method for preparing beta-hydroxyalkyl amide mainly comprises the steps of reacting dimethyl adipate and diethanol amine in a solvent methanol or reacting at high temperature in the absence of the solvent, and then putting the molten beta-hydroxyalkyl amide into methanol, toluene or acetone for recrystallization. However, the method uses a large amount of methanol and the like as a solvent, and has the following defects:

1. the use of methanol or the like as a solvent not only increases the solvent consumption and the post-treatment step, but also causes environmental pollution due to volatilization of the crystallization solvent.

2. The high-temperature melting reaction easily turns yellow, and recrystallization and decoloration are carried out.

3. The total yield is low.

CN107266331A discloses a trifunctional beta-hydroxyalkylamide, a preparation method thereof and a powder coating composition containing the same, and particularly discloses a method for melt reaction of diethanol amine, monoethanolamine and adipic acid which are used as main raw materials under the condition of no solvent, then a vacuum film is evaporated to remove volatile components, and then the volatile components are cooled and formed by a quick cooling steel belt. The synthesis method has large investment on equipment and is difficult to grasp at the control point in actual operation.

Therefore, there is a need to develop a safe, environment-friendly, high-yield, simple-operation and low-investment preparation method, so that the preparation of the beta-hydroxyalkylamide curing agent has industrial applicability and popularization.

Disclosure of Invention

The invention aims to: the preparation method of the beta-hydroxyalkylamide curing agent has the advantages of high curing agent yield, no generation of waste water, waste liquid and waste solids, environmental protection, less equipment investment and simple operation.

The technical scheme adopted by the invention is as follows:

in order to achieve the above object, the present invention provides a method for preparing a β -hydroxyalkylamide curing agent, comprising the following steps:

(1) mixing dimethyl adipate or diethyl adipate and diethanol amine, adding a catalyst, heating, decompressing and evaporating volatile components to obtain a tetrahydroxyethyl adipamide solution serving as a product A; the reaction formula is as follows:

(2) solidifying, crushing and drying the product A to obtain white powder solid, namely the tetrahydroxyethyl adipamide (beta-hydroxyalkylamide) solidifying agent.

Preferably, the molar ratio of the diethanolamine to the adipic acid dimethyl ester or adipic acid diethyl ester is 1.8-2.5.

Preferably, the molar ratio of the diethanolamine to the adipic acid dimethyl ester or adipic acid diethyl ester is 2.0-2.4.

Preferably, the catalyst is any one or any combination of potassium methoxide, potassium ethoxide, potassium acetate, potassium benzoate, potassium adipate and potassium hydroxide.

Preferably, the weight percentage of the catalyst to the product A is 0.11-0.14%.

Preferably, the reaction temperature of the step (1) is 65-85 ℃.

Preferably, the curing time of the step (2) is 8-12 hours.

Preferably, the drying temperature in the step (2) is 85-100 DEG C

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. in the preparation process of the curing agent, dangerous methanol is not used as a solvent, a target product and a small amount of byproduct methanol or ethanol are produced by reaction in a solvent-free state, the yield of the curing agent is high, the molar yield can reach 100%, and the byproduct methanol or ethanol is directly recycled.

2. The invention does not generate any waste water, waste liquid and waste solids in the preparation process of the curing agent, even a small amount of by-product methanol or ethanol can be recycled, the invention is a very green, safe and environment-friendly curing agent preparation process, and has very strong industrial applicability and popularization.

3. The equipment used in the preparation process of the curing agent is conventional equipment, the equipment investment is less, the operation unit is simple, and the operation is easy.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.