阅读说明：本技术 一种水性超支化聚酯基环氧固化剂及其制备方法 (Waterborne hyperbranched polyester-based epoxy curing agent and preparation method thereof ) 是由 夏正斌 李陈成 于 2021-09-06 设计创作，主要内容包括：本发明属于水性环氧树脂固化剂领域,公开了一种水性超支化聚酯基环氧固化剂的制备方法,包括如下步骤：将固态端羧基超支化聚酯树脂在丙二醇甲醚醋酸酯助溶剂中加热至溶解；再加入单端环氧聚二甲基硅氧烷和催化剂,混合均匀后,在100℃～130℃条件下,反应4～5h；将上述反应物冷却后,再加入有机胺中和,最后加水高速搅拌,得到水性超支化聚酯基环氧固化剂水分散液。本发明整个工艺流程简单,制备的水性超支化聚酯基环氧固化剂赋予水性环氧涂层优异的韧性、低表面能和优异的耐腐蚀性能。(The invention belongs to the field of waterborne epoxy resin curing agents, and discloses a preparation method of a waterborne hyperbranched polyester-based epoxy curing agent, which comprises the following steps: heating solid carboxyl-terminated hyperbranched polyester resin in a propylene glycol methyl ether acetate cosolvent until the solid carboxyl-terminated hyperbranched polyester resin is dissolved; then adding single-end epoxy polydimethylsiloxane and a catalyst, uniformly mixing, and reacting for 4-5 h at the temperature of 100-130 ℃; and cooling the reactants, adding organic amine for neutralization, and finally adding water for high-speed stirring to obtain the aqueous hyperbranched polyester-based epoxy curing agent aqueous dispersion. The whole process flow is simple, and the prepared waterborne hyperbranched polyester-based epoxy curing agent endows the waterborne epoxy coating with excellent toughness, low surface energy and excellent corrosion resistance.)

1. A preparation method of a waterborne hyperbranched polyester-based epoxy curing agent is characterized by comprising the following steps:

heating solid carboxyl-terminated hyperbranched polyester resin in a propylene glycol methyl ether acetate cosolvent until the solid carboxyl-terminated hyperbranched polyester resin is dissolved; then adding single-end epoxy polydimethylsiloxane and a catalyst, uniformly mixing, and reacting for 4-5 h at the temperature of 100-130 ℃; and cooling the reactants, adding organic amine for neutralization, and finally adding water for high-speed stirring to obtain the aqueous hyperbranched polyester-based epoxy curing agent aqueous dispersion.

2. The preparation method according to claim 1, wherein the carboxyl number n of the carboxyl-terminated hyperbranched polyester resin is 6-48, the molecular weight is 1 k-12 k, and the simplified structural formula is as follows:

3. the preparation method according to claim 2, wherein the carboxyl number n of the carboxyl-terminated hyperbranched polyester resin is 6-24.

4. The preparation method according to claim 1, wherein the epoxy value of the said one-terminal epoxy polydimethylsiloxane is 0.075-0.0055, and the simplified structure is as follows:

5. the method according to claim 4, wherein the epoxy value of the epoxy terminated polydimethylsiloxane is 0.04 to 0.0125.

6. The method according to any one of claims 1 to 5, wherein the catalyst is one or more of triphenylphosphine, 2-phenylimidazole, boron trifluoride diethyl etherate, and tetrabutylammonium bromide.

7. The method according to claim 6, wherein the organic amine neutralizer is one or more of diethylamine, triethylamine, ethanolamine, and diethanolamine.

8. The preparation method according to claim 7, wherein the charging mass ratio of the single-end epoxy polydimethylsiloxane to the carboxyl-end hyperbranched polyester resin is 0.5-3%; the feeding mass ratio of the organic amine to the carboxyl-terminated hyperbranched polyester resin is 10-25%.

9. The preparation method according to claim 8, wherein the high-speed stirring condition is 6000 to 7500 rpm; the solid content of the waterborne hyperbranched polyester-based epoxy curing agent is 50-60%.

10. The waterborne hyperbranched polyester-based epoxy curing agent prepared by the method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of waterborne epoxy resin curing agents, and particularly relates to a waterborne hyperbranched polyester-based epoxy curing agent and a preparation method thereof.

Background

The epoxy resin coating has the advantages of excellent physical and mechanical properties, high adhesive force, chemical resistance, flexible use process and the like, and is widely applied to the fields of building, chemical engineering, mechanical and electronic packaging and the like. However, the product mainly adopts a solvent type, releases a large amount of VOCs in the processes of manufacturing, constructing, curing and film forming, and has serious harm to human health and ecological environment. Therefore, water-based epoxy coatings using water as a solvent or dispersion medium have been increasingly favored. Because the epoxy resin is thermosetting resin, the epoxy resin has no use value when independently forming a film, and only when an epoxy curing agent is added, a three-dimensional network cross-linked structure can be formed, and the excellent performance of the epoxy resin is shown.

Currently, commercially available waterborne epoxy curing agents are generally prepared by incorporating a hydrophilic segment into an epoxy-polyamine adduct. For example, CN110511356A discloses a waterborne epoxy resin curing agent of epoxy-polyamine adduct, which adopts epoxy phenyl silicone oil modified epoxy resin with excellent water resistance and good toughness to improve the problems of high water absorption rate, brittleness and the like of a waterborne epoxy coating film; CN113214455A discloses a toughening type waterborne epoxy curing agent, which is prepared by introducing toughening epoxy resin and hydrophilic segment alkyl polyethylene glycol monoglycidyl ether modified polyamine to obtain the curing agent with good water dispersibility, excellent toughness and compatibility with waterborne epoxy resin. However, such curing agents tend to introduce a large amount of hydrophilic groups, and the resulting coating film has high surface energy, resulting in a decrease in water resistance and corrosion resistance.

Disclosure of Invention

The invention aims to provide a low-surface-energy waterborne hyperbranched polyester-based epoxy curing agent and a preparation method thereof, and solves the problems that a coating obtained by curing waterborne epoxy resin by using the existing curing agent is brittle, poor in water resistance, insufficient in long-term corrosion resistance and the like.

The technical scheme adopted by the invention is as follows:

a preparation method of a waterborne hyperbranched polyester-based epoxy curing agent comprises the following steps:

heating solid carboxyl-terminated hyperbranched polyester resin in a propylene glycol methyl ether acetate cosolvent until the solid carboxyl-terminated hyperbranched polyester resin is dissolved; then adding single-end epoxy polydimethylsiloxane and a catalyst, uniformly mixing, and reacting for 4-5 h at the temperature of 100-130 ℃; and cooling the reactants, adding organic amine for neutralization, and finally adding water for high-speed stirring to obtain the colorless and transparent aqueous hyperbranched polyester-based epoxy curing agent aqueous dispersion.

Preferably, the carboxyl number n of the carboxyl-terminated hyperbranched polyester resin is 6-48, the molecular weight is 1 k-12 k, and the simplified structural formula is as follows:

preferably, the carboxyl number n of the carboxyl-terminated hyperbranched polyester resin is 6-24.

Preferably, the epoxy value of the single-end epoxy polydimethylsiloxane is 0.075-0.0055, and the simplified structure is as follows:

preferably, the epoxy value of the single-end epoxy polydimethylsiloxane is 0.04-0.0125.

Preferably, the catalyst is one or more of triphenylphosphine, 2-phenylimidazole, boron trifluoride diethyl etherate and tetrabutylammonium bromide.

Preferably, the organic amine neutralizer is one or more than two of diethylamine, triethylamine, ethanolamine and diethanolamine;

preferably, the feeding mass ratio of the single-end epoxy polydimethylsiloxane to the carboxyl-end hyperbranched polyester resin is 0.5-3%; the feeding mass ratio of the organic amine to the carboxyl-terminated hyperbranched polyester resin is 10-25%.

Preferably, the high-speed stirring condition is 6000-7500 rpm; the solid content of the final waterborne hyperbranched polyester-based epoxy curing agent is 50-60%.

The principle of the invention is that carboxyl-terminated hyperbranched polyester is particularly selected as an epoxy resin curing agent, so that the toughness and the water resistance of the epoxy resin are improved. Meanwhile, the hyperbranched polyester resin modified by the single-ended epoxy polydimethylsiloxane is selected, so that the coating film can have high toughness and low surface energy. In addition, the organic amine is adopted to neutralize the terminal carboxyl of the hyperbranched polyester to ensure that the hyperbranched polyester is dispersed in water, so that the problem of water resistance reduction of a coating caused by introducing a hydrophilic chain segment into a conventional polyamine curing agent is solved. The whole process flow is simple, and the prepared waterborne hyperbranched polyester-based epoxy curing agent endows a waterborne epoxy coating film with high toughness, low surface energy and excellent corrosion resistance.

The preparation method and the obtained product have the following advantages and beneficial effects:

(1) the waterborne hyperbranched epoxy curing agent has simple synthesis process, good stability and high suitability with waterborne epoxy resin.

(2) The fluorine-free water-based epoxy coating system with low surface energy is environment-friendly and safe, has the advantage of cost performance, and adopts industrial and marketable raw materials.

(3) The coating can be suitable for various base materials such as metal, glass, plastics, woodware, ceramics and the like, and has good adhesive force.

(4) The coating has high hardness and good toughness.

(5) The coating has excellent water resistance and corrosion resistance.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

The carboxyl-terminated hyperbranched polyester resin is selected from Hyper-C102 of Wuhan hyperbranched resin science and technology Limited.

The single-end epoxy polydimethylsiloxane is selected from Anhui Egyta Silicone oil Co.

Example 1

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. Then 0.13g of single-end epoxy polydimethylsiloxane (with the epoxy value n being 0.025) is added, then boron trifluoride diethyl etherate is added, the mixture is stirred evenly, the temperature is raised to 110 ℃, and the reaction is kept for 5 hours. And cooling to room temperature, adding 4g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Example 2

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. And then adding 0.26g of single-ended epoxy polydimethylsiloxane (with the epoxy value n being 0.025), uniformly stirring, adding boron trifluoride diethyl etherate, heating to 110 ℃, and carrying out heat preservation reaction for 4-5 hours. And cooling to room temperature, adding 4g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Example 3

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. And then adding 0.52g of single-ended epoxy polydimethylsiloxane (with the epoxy value n being 0.025), uniformly stirring, adding boron trifluoride diethyl etherate, heating to 110 ℃, and carrying out heat preservation reaction for 4-5 hours. And cooling to room temperature, adding 4g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Example 4

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. And then adding 0.72g of single-ended epoxy polydimethylsiloxane (with the epoxy value n being 0.025), uniformly stirring, adding boron trifluoride diethyl etherate, heating to 110 ℃, and carrying out heat preservation reaction for 4-5 hours. And cooling to room temperature, adding 4g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Example 5

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. And then adding 0.52g of single-ended epoxy polydimethylsiloxane (the epoxy value n is 0.04), uniformly stirring, adding boron trifluoride diethyl etherate, heating to 110 ℃, and carrying out heat preservation reaction for 4-5 hours. And cooling to room temperature, adding 4g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Example 6

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. And then adding 0.52g of single-end epoxy polydimethylsiloxane (with the epoxy value n being 0.0125), uniformly stirring, adding boron trifluoride diethyl etherate, heating to 110 ℃, and carrying out heat preservation reaction for 4-5 hours. And cooling to room temperature, adding 4g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Comparative example 1

26g of carboxyl-terminated hyperbranched resin is added into a 250mL three-neck flask provided with a stirrer and a condenser, 6g of propylene glycol methyl ether acetate is added, and the temperature of an oil bath is raised to 90 ℃ to dissolve the resin. And cooling to room temperature, adding 5g of triethylamine for neutralization reaction for 30min, and then adding deionized water for high-speed (6000-7500 rpm) dispersion for 30min to obtain a colorless transparent water dispersion with the solid content of 55%.

Comparative example 2

Commercially available epoxy-polyamine waterborne epoxy curing agents.

The aqueous epoxy curing agents obtained in examples 1 to 6 and comparative examples 1 to 2 were mixed with a commercially available aqueous epoxy resin (3 EE104W from Gagmingshangde resin Co., Ltd., Fushan) in a stoichiometric ratio of 0.9: 1. Then, coating on a steel plate, standing at room temperature for 1-2 h, curing at 120-150 ℃ for 2-3 h, wherein the test results of the coating performance corresponding to different curing agents are shown in Table 1.

Table 1: results of film property test obtained after curing of each example and comparative example

The above test results were referenced to the following test methods or standards:

the adhesion is determined by a grid-scribing method, GB/T9286-1998;

measuring the pencil hardness of the paint film, GB/T6739-1996;

the flexibility of the paint film is measured, GB/T1731-1993;

determination of Water resistance, GB/1733 + 1993;

the test method for the salt water resistance comprises the following steps: soaking the coated steel plate in 3.5 wt% sodium chloride solution for 30d, observing whether the surface of the coated steel plate is foamed or whitish, and whether the surface of the iron base material is corroded or not and the corrosion severity;

water contact angle test: the contact angle measuring instrument is used in Shanghai and Zhongchen JC 2000D.

The comparison result shows that the toughness, the water resistance and the corrosion resistance of the waterborne epoxy coating prepared by the waterborne hyperbranched polyester-based epoxy curing agent and the preparation method thereof are obviously improved.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.