阅读说明：本技术 一种聚天门冬氨酸酯及其制备方法和应用 (Polyaspartic acid ester and preparation method and application thereof ) 是由 朱银邦 赵军子 卢鹏飞 徐轶 于 2021-06-22 设计创作，主要内容包括：本发明公开了一种聚天门冬氨酸酯及其制备方法和应用,制备方法包括如下步骤：(1)用马来酸酐和环氧单体反应得到马来酸二醇酯；(2)用步骤(1)得到的马来酸二醇酯和伯胺反应得到所述聚天门冬氨酸酯。将所述聚天门冬氨酸酯及异氰酸酯固化剂混合后,可得到聚天门冬氨酸酯聚脲涂料。本发明先用环氧单体改性马来酸酐合成马来酸二醇酯,再与伯胺反应,可制得多官能度聚天门冬氨酸酯,提高涂层的力学性能；并且合成的马来酸二醇酯无反式结构、产物酸值低,制成的涂料粘度增加慢,利于施工渗透。(The invention discloses polyaspartic acid ester and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) reacting maleic anhydride with an epoxy monomer to obtain maleic acid glycol ester; (2) and (2) reacting the glycol maleate obtained in the step (1) with primary amine to obtain the polyaspartic acid ester. And mixing the polyaspartic ester and an isocyanate curing agent to obtain the polyaspartic ester polyurea coating. According to the invention, firstly, the epoxy monomer is used for modifying maleic anhydride to synthesize glycol maleate, and then the glycol maleate reacts with primary amine, so that the polyaspartic acid ester with multiple functionalities can be prepared, and the mechanical property of the coating is improved; and the synthesized glycol maleate has no trans-structure and low acid value of the product, and the prepared coating has slow viscosity increase and is beneficial to construction penetration.)

1. A polyaspartic acid ester is characterized in that the polyaspartic acid ester is prepared by reacting glycol maleate obtained by reacting an epoxy monomer with maleic anhydride with primary amine, and the structural formula of the polyaspartic acid ester is as follows:

wherein R is₁、R₂、R₃And R₄Each independently is one of hydrogen, methyl, dimethyl, C2-C4 straight chain or branched chain alkyl and cycloalkyl;

R₅and R₆Is one of polyether group, polyethylene glycol group, C2-C10 straight chain or branched chain alkyl, cycloalkyl, ether group and ester group;

R₇and R₈Each independently is one of hydrogen, methyl, dimethyl, C2-C4 straight chain or branched chain alkyl;

R₉is one of ethyl, propyl and benzyl.

2. A method of preparing a polyaspartic acid ester as claimed in claim 1, comprising the steps of:

(1) reacting maleic anhydride with an epoxy monomer to obtain maleic acid glycol ester;

(2) and (2) reacting the glycol maleate obtained in the step (1) with primary amine to obtain the polyaspartic acid ester.

3. The process according to claim 2, wherein the epoxy monomer is a monofunctional epoxy monomer and the primary amine is R when the formula (I) is represented by₅A diamine group;

the monobasic epoxy monomer is one or more selected from ethylene oxide, propylene oxide, methyl propylene oxide, butylene oxide and cyclopentane oxide;

the R is₅The diamine is selected from one of polyether amine, polyethylene glycol amine, 1, 6-hexamethylene diamine, 4' -diaminodicyclohexyl methane and isophorone diamine.

4. The method for preparing polyaspartic acid ester according to claim 3, wherein when the structural formula is (I), the molar ratio of maleic anhydride to the mono-epoxy monomer in the step (1) is 1: 2-2.4; the reaction conditions of the step (1) are as follows: mixing maleic anhydride and a monobasic epoxy monomer, adding a catalyst, and reacting for 2-6 hours at the temperature of 60-90 ℃; the catalyst is triphenylphosphine, and the using amount of the catalyst is 0.01-0.1% of the mass of the reactant.

5. The process according to claim 3 or 4, wherein the diol maleate and R in step (2) are represented by formula (I)₅The molar ratio of the diamine is 2-2.4: 1; the reaction conditions of the step (2) are as follows: r is to be₅Mixing the diamine and sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03-0.1% of the mass of the reaction; dropwise adding glycol maleate into the mixture at 40-45 ℃ under the protection of nitrogen, wherein the dropwise adding time is controlled to be 40-80 min; and then heating to 60-80 ℃, introducing nitrogen, and reacting for 16-30 hours to obtain the polyaspartic acid ester.

6. The method for preparing polyaspartic acid ester according to claim 2, wherein when the structural formula is (II), maleic anhydride is reacted with a binary epoxy monomer in the step (1), and the product is reacted with a monobasic epoxy monomer to obtain maleic acid diol ester; the primary amine in the step (2) is R₉A monoamine;

the binary epoxy monomer is selected from one of epoxy resin ERL4221, epoxy resin ERL4299 and 1, 4-butanediol glycidyl ether;

the monobasic epoxy monomer is one or more selected from ethylene oxide, propylene oxide, methyl propylene oxide, butylene oxide and cyclopentane oxide;

the R is₉The primary monoamine is selected from one of ethylamine, propylamine and benzylamine.

7. The preparation method of polyaspartic acid ester according to claim 6, wherein when the structural formula is (II), the molar ratio of maleic anhydride, the binary epoxy monomer and the monobasic epoxy monomer in the step (1) is 2:1: 2-2.2; the reaction conditions of the step (1) are as follows: mixing maleic anhydride and a binary epoxy monomer, adding a catalyst, and reacting for 2-6 h at 60-90 ℃; then adding a monobasic epoxy monomer to continue reacting for 2-6 h; the catalyst is triphenylphosphine, and the using amount of the catalyst is 0.01-0.1% of the mass of the reactant.

8. The process according to claim 6 or 7, wherein the diol maleate and R in step (2) are represented by formula (II)₉The molar ratio of the primary monoamine is 1: 2-2.4; the reaction conditions of the step (2) are as follows: r is to be₉Mixing the primary monoamine with sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03-0.1% of the mass of the reaction mass; dropwise adding glycol maleate into the mixture at 40-45 ℃ under the protection of nitrogen, wherein the dropwise adding time is controlled to be 40-80 min; and then heating to 60-80 ℃, introducing nitrogen, and reacting for 16-30 hours to obtain the polyaspartic acid ester.

9. Use of a polyaspartic ester as claimed in claim 1 in a coating, wherein the coating comprises the polyaspartic ester and an isocyanate curing agent.

Technical Field

The invention relates to the field of polymer synthesis, in particular to polyaspartic acid ester and a preparation method and application thereof.

Background

The polyaspartic acid ester resin is a special steric hindrance type secondary amine compound, the activity of the secondary amine in the reaction with-NCO is reduced under the combined action of steric hindrance and induction effect, and compared with the traditional polyurea material, the polyaspartic acid ester resin has longer construction time and higher paint film adhesion. The polyaspartic ester polyurea coating prepared by matching polyaspartic ester resin with an aliphatic isocyanate curing agent has excellent mechanical property and aging resistance, and has more excellent drying speed compared with common hydroxyl resin and epoxy resin.

Polyaspartic acid ester in the prior art is generally obtained by reacting dialkyl maleate with fatty primary amines, wherein the dialkyl maleate is prepared by esterification reaction of maleic anhydride and alcohol; the dialkyl maleate is generally in excess during the reaction, so that the primary aliphatic amine can be fully converted into the hindered amine. For example, the publication "a new structure of aspartate resin and polyurea coating, its preparation method and application" in the chinese patent literature, publication No. CN109912442A, discloses that aspartate resin uses michael addition reaction between unsaturated dicarboxylic acid ester and unsaturated monocarboxylic acid ester, wherein the unsaturated dicarboxylic acid ester is dialkyl maleate or dialkyl fumarate, and primary amino compound; the unsaturated monocarboxylic acid ester is an alkyl acrylate or an alkyl methacrylate.

However, the method of the prior art has the following problems in the preparation of the reaction raw material of the polyaspartic acid ester, namely, the dialkyl maleate: 1. the esterification temperature is high when the maleic anhydride reacts with alcohol, a trans-structure is easily generated, the subsequent reaction with primary amine is not facilitated, and the primary amine is not fully converted, so that the early viscosity is quickly increased when the maleic anhydride is used in the coating, and the construction operation time is short; the product is easy to oxidize at high temperature, and the quality of the product is influenced; 2. the esterification of maleic anhydride and alcohol is difficult, and the synthesized dialkyl maleate has high acid value along with reverse reaction, and when the polyaspartic acid ester prepared by the maleic anhydride and the alcohol is used in paint, the polyaspartic acid ester is easy to react with isocyanate curing agent to generate carbon dioxide, so that the coating is easy to generate bubbles, and the performance of the coating is poor; 3. the esterification reaction of maleic anhydride and alcohol requires the solvent to be dehydrated with water, which is not environment-friendly; 4. the polyaspartic acid ester resin synthesized by the method in the prior art is mostly dual-functionality resin, the proportioning range of the polyaspartic acid ester resin and a curing agent is narrow, and the mechanical property of a cured coating is not good, so that the use of the coating is not facilitated.

Disclosure of Invention

The invention is in order to overcome the above-mentioned problem that exists when adopting dialkyl maleate and primary amine reaction that maleic anhydride and alcohol reaction get to prepare polyaspartic acid ester in prior art, provide a polyaspartic acid ester and its preparation method and application, react with maleic anhydride and synthesize glycol ester of maleic acid with epoxy monomer first, react with primary amine, can make poly aspartic acid ester of multiple functionality; the synthesized glycol maleate has no trans-structure and low acid value of the product, the viscosity of the prepared coating is slowly increased, the coating is favorable for construction penetration, bubbles are not easily generated in the coating, and the performance of the coating is improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

a polyaspartic acid ester is prepared by reacting a glycol maleate obtained by reacting an epoxy monomer with maleic anhydride with a primary amine, and has a structural formula:

wherein R is₁、R₂、R₃And R₄Each independently is one of hydrogen, methyl, dimethyl, C2-C4 straight chain or branched chain alkyl and cycloalkyl;

R₅and R₆Is one of polyether group, polyethylene glycol group, C2-C10 straight chain or branched chain alkyl, cycloalkyl, ether group and ester group;

R₇and R₈Each independently is one of hydrogen, methyl, dimethyl, C2-C4 straight chain or branched chain alkyl;

R₉is one of ethyl, propyl and benzyl.

The invention also discloses a preparation method of the polyaspartic acid ester, which comprises the following steps:

(1) reacting maleic anhydride with an epoxy monomer to obtain maleic acid glycol ester;

(2) and (2) reacting the glycol maleate obtained in the step (1) with primary amine to obtain the polyaspartic acid ester.

Preferably, when the structural formula is (I), the epoxy monomer is a monofunctional epoxy monomer, and the primary amine is R₅A diamine group; the monobasic epoxy monomer is one or more selected from ethylene oxide, propylene oxide, methyl propylene oxide, butylene oxide and cyclopentane oxide; the R is₅The diamine is selected from one of polyether amine, polyethylene glycol amine, 1, 6-hexamethylene diamine, 4' -diaminodicyclohexyl methane and isophorone diamine.

Preferably, when the structural formula is (I), the molar ratio of the maleic anhydride to the monobasic epoxy monomer in the step (1) is 1: 2-2.4; the reaction conditions of the step (1) are as follows: mixing maleic anhydride and a monobasic epoxy monomer, adding a catalyst, and reacting for 2-6 hours at the temperature of 60-90 ℃; the catalyst is triphenylphosphine, and the using amount of the catalyst is 0.01-0.1% of the mass of the reactant.

Preferably, when the structural formula is (I), the maleic acid glycol ester and R in the step (2)₅The molar ratio of the diamine is 2-2.4: 1; the reaction conditions of the step (2) are as follows: r is to be₅Mixing diamine and sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03-0.1% of the mass of a reactant; dropwise adding glycol maleate into the mixture at 40-45 ℃ under the protection of nitrogen, wherein the dropwise adding time is controlled to be 40-80 min; and then heating to 60-80 ℃, introducing nitrogen, and reacting for 16-30 hours to obtain the polyaspartic acid ester.

Preferably, when the structural formula is (II), maleic anhydride reacts with a binary epoxy monomer in the step (1), and the product reacts with a monobasic epoxy monomer to obtain glycol maleate; the primary amine in the step (2) is R₉A monoamine; the binary epoxy monomer is selected from one of epoxy resin ERL4221, epoxy resin ERL4299 and 1, 4-butanediol glycidyl ether; the monobasic epoxy monomer is one or more selected from ethylene oxide, propylene oxide, methyl propylene oxide, butylene oxide and cyclopentane oxide; the R is₉The primary monoamine is selected from one of ethylamine, propylamine and benzylamine.

Preferably, when the structural formula is (II), the molar ratio of the maleic anhydride to the binary epoxy monomer to the monobasic epoxy monomer in the step (1) is 2:1: 2-2.2; the reaction conditions of the step (1) are as follows: mixing maleic anhydride and a binary epoxy monomer, adding a catalyst, and reacting for 2-6 h at 60-90 ℃; then adding a monobasic epoxy monomer to continue reacting for 2-6 h; the catalyst is triphenylphosphine, and the using amount of the catalyst is 0.01-0.1% of the mass of the reactant.

Preferably, when the structural formula is (II), the maleic acid glycol ester and R in the step (2)₉The molar ratio of the primary monoamine is 1: 2-2.4; the reaction conditions of the step (2) are as follows: r is to be₉Mixing the primary monoamine with sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03-0.1% of the mass of the reaction mass; dropwise adding glycol maleate into the mixture at 40-45 ℃ under the protection of nitrogen, wherein the dropwise adding time is controlled to be 40-80 min; and then heating to 60-80 ℃, introducing nitrogen, and reacting for 16-30 hours to obtain the polyaspartic acid ester.

The invention also discloses an application of the polyaspartic ester in a coating, and the coating comprises the polyaspartic ester and an isocyanate curing agent.

The invention uses the reaction of the diol maleate obtained by the reaction of the epoxy monomer and the maleic anhydride and the primary amine to prepare the polyaspartic acid ester with multiple functionality, and the reaction mechanism is as follows:

formula (I):

wherein R is selected from R₁、R₂、R₃Or R₄When maleic anhydride is reacted simultaneously with monofunctional epoxy monomers having different R groups, R in the resulting polyaspartic acid ester₁、R₂、R₃And R₄Are different groups.

The reaction mechanism of formula (II) is:

wherein R' is R₇Or R₈When the reaction product of maleic anhydride and the binary epoxy monomer reacts with the monobasic epoxy monomer with different R' groups, R in the finally obtained polyaspartic acid ester₇And R₈Are different groups.

According to the invention, firstly, in the step (1), an epoxy monomer reacts with maleic anhydride to obtain glycol maleate, and then in the step (2), the glycol maleate reacts with primary amine to obtain polyaspartic acid ester. When the glycol maleate is prepared in the step (1), the reaction temperature is low, the obtained glycol maleate has no trans-structure, the subsequent reaction with primary amine is facilitated, a solvent, a water-carrying agent and the like are not required in the reaction, and the synthetic process is more economic and environment-friendly; meanwhile, the esterification conversion rate in the step (1) is high, no by-product is generated in the reaction, and the acid value of the product is low, so that the early viscosity of the polyaspartic ester polyurea coating prepared by compounding the polyaspartic ester prepared from the glycol maleate and the isocyanate curing agent is slowly increased, the construction penetration is facilitated, the coating is not easy to generate bubbles, and the service performance of the coating is improved. Hydroxyl introduced into the polyaspartic ester molecules does not influence the reaction of secondary amine and isocyanate, the bonding strength of the polyaspartic ester molecules is improved, and epoxy groups can react with free amine in a system, so that the bonding strength of the product can be further improved; meanwhile, the product prepared by the invention is polyaspartic ester with multiple functionality, and the crosslinking density of the polyaspartic ester polyurea coating can be improved, so that the mechanical property of the coating is improved.

Therefore, the invention has the following beneficial effects:

(1) when the epoxy monomer is reacted with maleic anhydride to prepare the glycol maleate, the reaction temperature is lower than that required by common alcohol esterification, the esterification conversion rate is higher, no by-product is generated in the reaction, no solvent, water-carrying agent and the like are needed, and the synthetic process is more economic and environment-friendly;

(2) the synthesized product has no trans-structure and high acid value, the early viscosity of the polyaspartic ester polyurea coating obtained by compounding the synthesized product with an isocyanate curing agent is slowly increased, the construction penetration is facilitated, and the coating is not easy to generate bubbles;

(3) hydroxyl introduced into molecules does not influence the reaction of secondary amine and isocyanate, the bonding strength of the secondary amine is improved, and epoxy groups can react with free amine in a system, so that the bonding strength of the product can be further improved;

(4) the synthesized product is polyaspartic ester with multiple functions, and can improve the crosslinking density of polyaspartic ester polyurea coating, thereby improving the mechanical property of the coating.

Detailed Description

The invention is further described with reference to specific embodiments.

In the present invention, all the raw materials are commercially available or commonly used in the industry, and the methods in the following examples are conventional in the art unless otherwise specified.

Example 1:

a polyaspartic acid ester having the structural formula:

wherein R is₁、R₂、R₃And R₄Is methyl; r₅Is a polyether group.

The preparation method comprises the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, and dropwise adding propylene oxide, wherein the molar ratio of the maleic anhydride to the propylene oxide is 1:2.1, the addition amount of the MEHQ is 0.02% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.02% of the total mass of the reactants; controlling the dropping speed of the propylene oxide to ensure that the reaction temperature does not exceed 60 ℃, keeping the temperature for 2h at 70 ℃ after the dropping is finished, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain glycol maleate;

(2) adding polyetheramine D400 into a flask, adding sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03 percent of the total mass of reactants, introducing nitrogen, heating to 42 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel for 1h, wherein the molar ratio of the glycol maleate to the polyetheramine D400 is 2.1: 1; then heating to 70 ℃, introducing nitrogen to react for 18h, and obtaining the polyaspartic acid ester.

Example 2:

a polyaspartic acid ester having the structural formula:

wherein R is₁And R₂Is hydrogen, R₃And R₄Is methyl; r₅Is n-hexyl.

The preparation method comprises the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, dropwise adding a mixture of ethylene oxide and propylene oxide, wherein the molar ratio of the maleic anhydride to the ethylene oxide to the propylene oxide is 1:1:1, the addition amount of the MEHQ is 0.02% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.01% of the total mass of the reactants; controlling the dropping speed of the ethylene oxide and the propylene oxide to ensure that the reaction temperature does not exceed 60 ℃, keeping the temperature for 6 hours at 60 ℃ after the dropping is finished, measuring the acid value every 0.5 hour, and discharging when the acid value reaches 2mgKOH/g to obtain the glycol maleate;

(2) adding 1, 6-hexamethylenediamine into a flask, adding sodium methoxide, wherein the addition amount of the sodium methoxide is 0.05 percent of the total mass of reactants, introducing nitrogen, heating to 40 ℃, and then dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel for 80min, wherein the molar ratio of the glycol maleate to the 1, 6-hexamethylenediamine is 2: 1; then heating to 60 ℃, introducing nitrogen to react for 30h, and obtaining the polyaspartic acid ester.

Example 3:

a polyaspartic acid ester having the structural formula:

wherein R is₁、R、R₃And R₄Are each hydrogen, methyl, ethyl anda cyclopentyl group; r₅Is a cycloalkyl group.

The preparation method comprises the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, dropwise adding a mixture of propylene oxide, ethylene oxide, butylene oxide and 1, 2-epoxycyclopentane in a molar ratio of 1:1:1:1, wherein the molar ratio of epoxy groups in the maleic anhydride and the mixture is 1:2.4, the addition amount of the MEHQ is 0.02 percent of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.1 percent of the total mass of the reactants; controlling the dripping speed of the epoxy mixture to ensure that the reaction temperature does not exceed 60 ℃, keeping the temperature for 2h at 70 ℃ after dripping is finished, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain glycol maleate;

(2) adding isophorone diamine into a flask, adding sodium methoxide, wherein the addition amount of sodium methoxide is 0.1 percent of the total mass of reactants, introducing nitrogen, heating to 45 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel for 40min, wherein the molar ratio of the glycol maleate to the isophorone diamine is 2.4: 1; then heating to 80 ℃, introducing nitrogen to react for 16h, and obtaining the polyaspartic acid ester.

Example 4:

a polyaspartic acid ester having the structural formula:

wherein R is₆Is an alicyclic ester group; r₇And R₈Is methyl, R₉Is benzyl.

The preparation method comprises the following steps:

(1) adding maleic anhydride, polymerization inhibitor p-hydroxyanisole (MEHQ) and catalyst triphenylphosphine into a flask, and dropwise adding epoxy resin ERL4221, wherein the molar ratio of the maleic anhydride to the epoxy resin ERL4221 is 2:1, the addition amount of the MEHQ is 0.1% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.1% of the total mass of the reactants; after the dropwise addition is finished, preserving the heat for 5 hours at 70 ℃; cooling to 50 ℃, dropwise adding propylene oxide, keeping the molar ratio of maleic anhydride to propylene oxide at 1:1.05, keeping the temperature for 2h at 70 ℃ after dropwise adding, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain maleic acid glycol ester;

(2) adding phenylmethylamine into a flask, adding sodium methoxide, introducing nitrogen, heating to 42 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel, wherein the addition amount of the sodium methoxide is 0.03 percent of the total mass of reactants, and the dropwise adding time is 1h, and the molar ratio of the glycol maleate to the phenylmethylamine is 1: 2.1; then heating to 70 ℃, introducing nitrogen to react for 24 hours to obtain the polyaspartic acid ester.

Example 5:

a polyaspartic acid ester having the structural formula:

wherein R is₆Is a glycidyl ether group; r₇Is hydrogen, R₈Is methyl, R₉Is ethyl.

The preparation method comprises the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, dropwise adding 1, 4-butanediol glycidyl ether, wherein the molar ratio of the maleic anhydride to the 1, 4-butanediol glycidyl ether is 2:1, the addition amount of the MEHQ is 0.1% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.05% of the total mass of the reactants; after the dropwise addition is finished, preserving the heat for 6 hours at 60 ℃; cooling to 50 ℃, dropwise adding propylene oxide, keeping the molar ratio of maleic anhydride to propylene oxide at 1:1, keeping the temperature at 60 ℃ for 6h after dropwise adding, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain glycol maleate;

(2) adding ethylamine into a flask, adding sodium methoxide, introducing nitrogen, heating to 40 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel, wherein the addition amount of the sodium methoxide is 0.05% of the total mass of reactants, and the dropwise adding time is 80min, and the molar ratio of the glycol maleate to the benzylamine is 1: 2; then heating to 60 ℃, introducing nitrogen to react for 30h, and obtaining the polyaspartic acid ester.

Comparative example 1 (half of the epoxidized diester maleate reacted with half of the esterification with the primary amine):

a polyaspartic acid ester is prepared by the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, firstly dropwise adding ethanol with a molar ratio of 1:1 to the maleic anhydride at 60 ℃, preserving heat for 5 hours at 60 ℃ after dropwise adding, continuously dropwise adding propylene oxide with a molar ratio of 1.05:1 to the maleic anhydride, wherein the addition amount of the MEHQ is 0.02 percent of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.1 percent of the total mass of the reactants; controlling the dropping speed of the propylene oxide to ensure that the reaction temperature does not exceed 60 ℃, keeping the temperature for 2h at 70 ℃ after the dropping is finished, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain maleic acid diester;

(2) adding isophorone diamine into a flask, adding sodium methoxide, wherein the addition amount of sodium methoxide is 0.1 percent of the total mass of reactants, introducing nitrogen, heating to 45 ℃, dropwise adding the maleic diester obtained in the step (1) by using a constant-pressure dropping funnel for 40min, wherein the molar ratio of the maleic diester to the isophorone diamine is 2.4: 1; then heating to 80 ℃, introducing nitrogen to react for 16h, and obtaining the polyaspartic acid ester.

Comparative example 2 (reaction of dialkyl maleate with primary amine):

a polyaspartic acid ester is prepared by the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, and dropwise adding ethanol, wherein the molar ratio of the maleic anhydride to the ethanol is 1:2.1, the addition amount of the MEHQ is 0.02% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.02% of the total mass of the reactants; controlling the dripping speed of the ethanol to ensure that the reaction temperature does not exceed 60 ℃, keeping the temperature for 5 hours at 70 ℃ after dripping is finished, then heating to 150 ℃, adding dimethylbenzene for reflux dehydration reaction, and obtaining dialkyl maleate after 8 hours;

(2) adding 1, 6-hexamethylene diamine into a flask, adding sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03 percent of the total mass of reactants, introducing nitrogen, heating to 42 ℃, and then dropwise adding the dialkyl maleate obtained in the step (1) by using a constant-pressure dropping funnel for 1h, wherein the molar ratio of the dialkyl maleate to the 1, 6-hexamethylene diamine is 2.1: 1; then heating to 70 ℃, introducing nitrogen to react for 18h, and obtaining the polyaspartic acid ester.

Comparative example 3 (formula I mono-epoxy monomer too long carbon chain):

a polyaspartic acid ester having the structural formula:

wherein R is₁、R₂、R₃And R₄Is n-decaalkyl; r₅Is a polyether group.

The preparation method comprises the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, dropwise adding 1, 2-epoxy dodecane, wherein the molar ratio of the maleic anhydride to the 1, 2-epoxy dodecane is 1:2.1, the addition amount of the MEHQ is 0.02% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.02% of the total mass of the reactants; controlling the dropping speed of the 1, 2-epoxydodecane to ensure that the reaction temperature does not exceed 60 ℃, keeping the temperature for 2h at 70 ℃ after the dropping is finished, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain glycol maleate;

(2) adding polyetheramine D400 into a flask, adding sodium methoxide, wherein the addition amount of the sodium methoxide is 0.03 percent of the total mass of reactants, introducing nitrogen, heating to 42 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel for 1h, wherein the molar ratio of the glycol maleate to the polyetheramine D400 is 2.1: 1; then heating to 70 ℃, introducing nitrogen to react for 18h, and obtaining the polyaspartic acid ester.

Comparative example 4 (formula II epoxy monomer carbon chain too long):

a polyaspartic acid ester is prepared by the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, and dropwise adding epoxy resin E44, wherein the molar ratio of the maleic anhydride to the epoxy resin E44 is 2:1, the addition amount of the MEHQ is 0.1% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.1% of the total mass of the reactants; after the dropwise addition is finished, preserving the heat for 5 hours at 70 ℃; cooling to 50 ℃, dropwise adding 1, 2-epoxy dodecane, keeping the molar ratio of maleic anhydride to 1, 2-epoxy dodecane at 1:1.05, keeping the temperature at 70 ℃ for 2 hours after dropwise adding, measuring the acid value every 0.5 hour, and discharging when the acid value reaches 2mgKOH/g to obtain maleic acid glycol ester;

(2) adding phenylmethylamine into a flask, adding sodium methoxide, introducing nitrogen, heating to 42 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel, wherein the addition amount of the sodium methoxide is 0.03 percent of the total mass of reactants, and the dropwise adding time is 1h, and the molar ratio of the glycol maleate to the phenylmethylamine is 1: 2.1; then heating to 70 ℃, introducing nitrogen to react for 24 hours to obtain the polyaspartic acid ester.

Comparative example 5 (formula II esterification followed by epoxidation):

a polyaspartic acid ester is prepared by the following steps:

(1) adding maleic anhydride, a polymerization inhibitor p-hydroxyanisole (MEHQ) and a catalyst triphenylphosphine into a flask, and dropwise adding polyether glycol N210, wherein the molar ratio of the maleic anhydride to hydroxyl in the N210 is 2:1, the addition amount of the MEHQ is 0.1% of the total mass of reactants, and the addition amount of the triphenylphosphine is 0.1% of the total mass of the reactants; after the dropwise addition is finished, preserving the heat for 5 hours at 70 ℃; cooling to 50 ℃, dropwise adding propylene oxide, keeping the molar ratio of maleic anhydride to propylene oxide at 1:1.05, keeping the temperature for 2h at 70 ℃ after dropwise adding, measuring the acid value every 0.5h, and discharging when the acid value reaches 2mgKOH/g to obtain maleic acid glycol ester;

(2) adding phenylmethylamine into a flask, adding sodium methoxide, introducing nitrogen, heating to 42 ℃, dropwise adding the glycol maleate obtained in the step (1) by using a constant-pressure dropping funnel, wherein the addition amount of the sodium methoxide is 0.03 percent of the total mass of reactants, and the dropwise adding time is 1h, and the molar ratio of the glycol maleate to the phenylmethylamine is 1: 2.1; then heating to 70 ℃, introducing nitrogen to react for 24 hours to obtain the polyaspartic acid ester.

Comparative example 6:

a commercially available polyaspartic acid ester (sekkaido chemical limited, F520).

Application example:

the polyaspartic acid esters prepared in the above examples and comparative examples were mixed with an isocyanate curing agent in the weight parts shown in Table 1 to obtain polyaspartic acid ester polyurea coatings.

Table 1: and (4) proportioning the coating.

The performance of the coating is tested according to the method in the national standard GB/T22374-2018 of the terrace industry. The coating method is a rolling coating method, the thickness of a rolling coating paint film is 60-100 um, and detection is carried out after the paint film is uniformly condensed for 72 hours.

Table 2: and (5) testing the performance of the coating.

As can be seen from Table 2, the polyaspartic acid esters prepared by the method of the invention in examples 1-5 have fewer bubbles and longer construction operation time when used in a coating compared with the commercially available polyaspartic acid ester in comparative example 6, and are more beneficial to producing a high-quality coating in product construction.

Comparative example 2 dialkyl maleate obtained by high temperature esterification of maleic anhydride and monohydric alcohol is reacted with primary amine, and the operation time of the obtained product is too short compared with that of example 2, so that the product cannot be used; in comparative examples 1 and 5, maleic anhydride is firstly reacted with monohydric alcohol at low temperature, the first step is easier to obtain, and then the part needing high-temperature esterification in the second step adopts epoxy polymerization, so that the generation of a trans-structure is avoided, the acid value is also reduced, and the performance of the obtained product is improved compared with that in comparative example 2; comparative example 3 the epoxy monomer used in the preparation of polyaspartic acid ester in comparative example 4 has too long carbon chain, which results in increased viscosity of the coating and difficulty in application.