A polyaspartate and a method for its preparation

Abstract

The application provides a kind of polyaspartic ester and its preparation method.The preparation method of the polyaspartic ester first reacts polyvalent primary amine with maleate, then adds weather-resistant isocyanate to quickly consume the residual primary amine in the system. The application mainly solves the problem of high residual primary amine in the system at the later stage of the synthesis of the polyaspartic ester, which leads to the problem of too fast reaction speed of the synthesized polyaspartic ester with isocyanate curing agent. The reaction speed with isocyanate can be reduced while maintaining the low color number, high yellowing resistance and mechanical properties of the polyaspartic ester, which prolongs the usable time and has great application in the fields of aspartic urea joint sealant, aspartic paint and the like.

Description

Technical Field

[0001] This invention relates to a resin synthesis technology, and more particularly to a method for synthesizing polyaspartic acid ester resin. Background Technology

[0002] Polyaspartic acid ester resin is a resin containing secondary amine groups, obtained through the Michael addition reaction of di / tertiary primary amines and maleic acid esters. Due to the steric hindrance and inductive effect of the ester groups, the reactive hydrogens on this type of resin have reduced reactivity with isocyanates, resulting in longer application time and better paint film adhesion compared to traditional polyurea materials. Polyaspartic acid resin is typically used in combination with aliphatic isocyanates. This combination produces aspartic polyurea products with excellent weather resistance and mechanical properties, finding wide application in waterproofing, anti-corrosion coatings, sealant grout, and floor coatings.

[0003] Due to the influence of primary amine and maleate concentrations and steric hindrance during the later stages of polyaspartic ester synthesis, primary amine groups remain in the system. These residual primary amine groups react rapidly with isocyanates, generating significant heat, which greatly impacts construction time and efficiency, limiting the development of polyaspartic ester polyurea. Patent CN105440272A eliminates residual primary amines by adding cyclic carbonates; however, since cyclic carbonates hardly react with primary amines at room temperature, the reaction must be carried out under medium to high temperatures for extended periods. This method leads to a darker color in the polyaspartic ester product, reducing its weather resistance. Patent CN109320681A uses acrylates to eliminate residual primary amines, but this also suffers from the problem of low reaction rates between acrylates and primary amines at room temperature, requiring prolonged heating at medium to high temperatures to increase the reaction rate. This affects the color of the final polyaspartic ester product. Furthermore, the secondary amines obtained after the reaction of primary amines with acrylates have highly reactive hydrogens, resulting in a rapid reaction with isocyanates, making it difficult to effectively extend the usable time. Summary of the Invention

[0004] To address the issue of high residual primary amine groups in polyaspartic esters, this invention proposes a method for synthesizing polyaspartic ester resins. This method can rapidly react away the active hydrogen on the primary amines in the system under low-temperature conditions. The polyaspartic ester resin prepared by this method can reduce the reaction rate with aliphatic isocyanates during later use while maintaining low color number and high weather resistance.

[0005] To address the aforementioned problems, this invention discloses a method for preparing polyaspartic acid ester, which involves first reacting a binary / tertiary primary amine with a maleic acid ester, and then adding an isocyanate in the later stages of the reaction to consume the residual primary amine in the system.

[0006] A polyaspartic acid ester, the reactants of which are, in molar amounts of reactive groups, as follows:

[0007] 100 parts of polyamines (based on primary amine groups);

[0008] Maleate ester (calculated as C=C double bond group) 100-110 parts;

[0009] Isocyanate (calculated as -NCO group) 5-10 parts.

[0010] A method for preparing polyaspartic acid ester includes the following steps:

[0011] (1) The reaction of polyamines with maleic acid esters is carried out at a temperature of 40-60℃, preferably 45-55℃, and for a reaction time of 168-336h, preferably 192h-288h.

[0012] (2) The isocyanate reacts with the product of step (1) at a temperature of 20-40°C, preferably 23-35°C, for a time of 1-3 h, preferably 1.5-2 h.

[0013] Further, the polyamine is one or more selected from the following: pentanediamine, 1,2-propanediamine, 1,3-propanediamine, ethylenediamine, 2-methylpentanediamine, polyoxypropylene diamine (D230), polyoxypropylene diamine (D400), polyoxypropylene triamine (T403), 1,6-hexanediamine, 1,3-cyclohexanedimethylamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and isophorone diamine; preferably polyoxypropylene diamine (D230), polyoxypropylene triamine (T403), and 4,4'-diaminodicyclohexylmethane (H230). 12 One or more of MDA, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (DMDC), and isophorone diamine (IPDA).

[0014] Further, the maleic ester is one or more of diethyl maleate, dibutyl maleate, and dipropyl maleate; preferably one or more of diethyl maleate and dibutyl maleate.

[0015] Furthermore, the isocyanate is a weather-resistant isocyanate, preferably one or more trimers of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate, and more preferably one or more of isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

[0016] Furthermore, in the preparation method of the polyaspartic ester, the residual maleic ester needs to be removed by a thin-film evaporator in the later stage of aspartic resin synthesis.

[0017] Furthermore, the thin-film evaporator is used to remove maleic esters under vacuum conditions of 140-170℃, preferably 145℃-160℃ and 800-1000Pa, preferably 800-900Pa.

[0018] Furthermore, the basic properties of the polyaspartic ester resin of the present invention are tested by mixing aspartic resin and HDI trimer (HT-100) in equivalent amounts (i.e., the equivalent amount of secondary amine in aspartic resin and the equivalent amount of NCO in HT-100).

[0019] The polyaspartic acid ester of the present invention can be applied to aspartic polyurea grout, aspartic coatings and other fields.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) In this invention, isocyanate is added to the system in the later stage of the aspartic resin synthesis reaction. Under the premise that the isocyanate group can react with the primary amine within a few seconds, the residual primary amine can be quickly eliminated under low temperature conditions, so as to obtain polyaspartic ester resin with low primary amine residue.

[0022] (2) By adding isocyanate to the system in the later stage of the reaction, the present invention utilizes the characteristic of rapid reaction between isocyanate groups and primary amines at low temperature to produce urea. This can eliminate residual primary amines under low temperature conditions, avoid the problem of traditional synthesis requiring high temperature and long reaction time, reduce the color change of aspartic resin products, and maintain the low color number characteristic of polyaspartic ester resin.

[0023] (3) In this invention, isocyanate is added to the system in the later stage of the synthesis reaction. While eliminating the primary amine in the system, corresponding urea groups are generated. The presence of urea groups can effectively improve the mechanical properties of the final product.

[0024] (4) Compared with other methods of eliminating primary amines, the polyaspartic acid ester resin obtained by the present invention has a longer working time after being mixed with isocyanate curing agent HT-100; the use of bifunctional isocyanate to eliminate primary amines can improve the crosslinking density of the final product, thereby improving the hardness and tensile strength of the final product. Detailed Implementation

[0025] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0026] The raw materials and their sources are shown in Table 1:

[0027] Table 1. Raw Materials and Sources

[0028]

[0029]

[0030] Example 1

[0031] Polyaspartic acid esters were synthesized according to a molar ratio of active groups (primary amino groups, C=C double bonds, and -NCO groups) in 4,4'-diaminodicyclohexylmethane, diethyl maleate, and hexamethylene diisocyanate of 100:110:10.

[0032] First, 10500g of 4,4'-diaminodicyclohexylmethane (100mol-NH2) was weighed and added to the reaction vessel. Then, 18920g of diethyl maleate (110mol-C=C double bonds) was weighed and added to the dropping device, with the temperature controlled below 40℃ during the dropwise addition. After the dropwise addition was completed, the temperature was raised to 55℃ and the reaction was carried out for 288 hours. Next, 841g of hexamethylene diisocyanate (10mol-NCO groups) was weighed and added dropwise to the reaction vessel under high-speed stirring in the reactor, and the reaction was continued at 35℃ for 2 hours. Diethyl maleate was removed by vacuum removal in a thin-film evaporator at 160℃ and a vacuum degree of 900Pa to obtain the corresponding polyaspartic acid ester resin.

[0033] Example 2

[0034] Polyaspartic acid esters were synthesized according to a molar ratio of active groups (primary amino, C=C double bond, -NCO group) in polyoxypropylene triamine (T403): dibutyl maleate: isophorone diisocyanate of 100:100:5.

[0035] First, 13433g of polypropylene triamine (T403) (100mol-NH2) was weighed and added to the reaction vessel. Then, 22830g of dibutyl maleate (100mol C=C double bonds) was weighed and added to the dropping device, with the temperature controlled below 40℃ during the dropping process. After the dropping was completed, the temperature was raised to 45℃ and the reaction was carried out for 192 hours. Next, 555.5g of isophorone diisocyanate (5mol-NCO groups) was weighed and added dropwise to the reaction vessel under high-speed stirring, and the reaction was continued at 23℃ for 1.5 hours. Dibutyl maleate was removed by vacuum removal in a thin-film evaporator at 145℃ and a vacuum degree of 800Pa to obtain the corresponding polyaspartic acid ester resin.

[0036] Example 3

[0037] Polyaspartic acid esters were synthesized according to the following molar ratio of active groups (primary amino, C=C double bond, -NCO group) in isophorone diamine, polyoxypropylene diamine (D230), diethyl maleate, and dicyclohexylmethane diisocyanate: 100:105:7.

[0038] First, 4250g of isophorone diamine (50mol-NH2) and 5750g of polyoxypropylene diamine (D230) (50mol-NH2) were weighed and added to the reaction vessel. Then, 18060g of diethyl maleate (105mol C=C double bonds) was weighed and added to the dropping device, with the temperature controlled below 40℃ during the dropping process. After the dropping was completed, the temperature was raised to 50℃ and the reaction was carried out for 240 hours. Next, 917.7g of dicyclohexylmethane diisocyanate (7mol-NCO groups) was weighed and added dropwise to the reaction vessel under high-speed stirring, and the reaction was continued at 25℃ for 1.8 hours. Diethyl maleate was removed by vacuum removal in a thin-film evaporator at 152℃ and a vacuum degree of 850Pa to obtain the corresponding polyaspartic acid ester resin.

[0039] Example 4

[0040] Polyaspartic acid esters were synthesized according to a molar ratio of active groups (primary amino groups, C=C double bonds, and -NCO groups) in 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, diethyl maleate, dibutyl maleate, hexamethylene diisocyanate, and isophorone diisocyanate of 100:100:9.

[0041] First, 11920g of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (100mol-NH2) was weighed and added to the reaction vessel. Then, 8600g of diethyl maleate (50mol C=C double bonds) and 11415g of dibutyl maleate (50mol C=C double bonds) were weighed and added to a dropping apparatus. The temperature was controlled below 40℃ for the dropping process. After the dropping was completed, the temperature was raised to 47℃ and the reaction was allowed to proceed for 200 hours. Then, 378.5g of hexamethylene diisocyanate (4.5mol-NCO groups) and 500g of isophorone diisocyanate (4.5mol-NCO groups) were weighed and added to the reaction vessel. The reaction was continued at 30℃ for 1.8 hours. Diethyl maleate and dibutyl maleate were removed by vacuum evaporation at 151℃ and a vacuum degree of 830Pa to obtain the corresponding polyaspartic acid ester resin.

[0042] Comparative Example 1

[0043] Polyaspartic acid esters were synthesized according to a molar ratio of 4,4'-diaminodicyclohexylmethane to diethyl maleate (primary amino, C=C double bond) of 100:110.

[0044] First, 10500g of 4,4'-diaminodicyclohexylmethane (100mol-NH2) was weighed and added to the reaction vessel. Then, 18920g of diethyl maleate (110mol C=C double bonds) was weighed and added to the dropping apparatus. The temperature was controlled below 40℃ during the dropping process. After the dropping was completed, the temperature was raised to 55℃ and the reaction was carried out for 328 hours. Diethyl maleate was removed under vacuum in a thin-film evaporator at 160℃ and a vacuum degree of 900Pa to obtain the corresponding polyaspartic acid ester resin.

[0045] Comparative Example 2

[0046] Polyaspartic acid ester was synthesized according to the molar ratio of active groups (primary amino, C=C double bond, -five-membered ring group) in polypropylene triamine (T403): dibutyl maleate: propylene carbonate of 100:100:26.67.

[0047] First, 13433g of polypropylene triamine (T403) (100mol-NH2) was weighed and added to the reaction vessel. Then, 22830g of dibutyl maleate (100mol C=C double bonds) was weighed and added to the dropping device, with the temperature controlled below 40℃ during the dropping process. After the dropping was completed, the temperature was raised to 85℃ and the reaction was carried out for 10 hours. Next, 2720.34g of propylene carbonate (26.67mol-cyclic groups) was weighed and added dropwise to the reaction vessel under high-speed stirring, and the reaction was continued at 85℃ for 10 hours. Dibutyl maleate and propylene carbonate were removed by vacuum removal in a thin-film evaporator at 145℃ and a vacuum degree of 800Pa to obtain the corresponding polyaspartic acid ester resin.

[0048] The comparison results of the basic properties of the polyaspartic acid ester resins obtained in the examples and comparative examples are shown in Table 2 below:

[0049] Table 2 Basic Properties of Polyaspartic Acid Ester Resin

[0050]

[0051] The usable time test conditions were as follows: 40g of polyaspartic acid ester resin and HT-100 were mixed in equal amounts and tested at 25℃ and 50% humidity. Tensile test conditions: Curing process of the sample: 25℃, 50% humidity, cured for 48 hours before testing.

[0052] The comparison of the basic properties of the polyaspartic acid ester resins obtained in Example 1 and Comparative Example 1 shows that the method of using isocyanate to eliminate residual primary amines in the early stage of the reaction has a higher primary amine elimination efficiency, resulting in a polyaspartic acid ester resin with a lower color number and a longer usable time. The comparison of the basic properties of the polyaspartic acid ester resins obtained in Example 2 and Comparative Example 2 shows that compared with using cyclic carbonates for primary amine elimination, the method of using isocyanate to eliminate residual primary amines is more efficient, resulting in a polyaspartic acid ester resin with a lower color number, a longer usable time, and higher mechanical strength and hardness. Therefore, it can be seen that in the synthesis of polyaspartic acid ester resins, using isocyanate to eliminate residual primary amines has higher efficiency and can yield polyaspartic acid ester resins with lower color numbers, longer usable times, and better mechanical properties.

Claims

1. A polyaspartic ester, wherein the reactants, in terms of the molar number of reactive groups, are as follows: Polyamines, 100 parts based on primary amine groups; Maleate ester, calculated as C=C double bond groups, 100-110 parts; Isocyanate, 5-10 parts based on -NCO groups; The preparation method of the polyaspartic ester includes the following steps: (1) The reaction of polyamines with maleic esters is carried out at a temperature of 40-60℃ and a reaction time of 168-336h. (2) The isocyanate reacts with the product of step (1) at a temperature of 20-40℃ for 1-3 hours.

2. The polyaspartic acid ester according to claim 1, characterized in that, The polyamine is one or more selected from ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, pentanediamine, 2-methylpentanediamine, 1,6-hexanediamine, D230, D400, T403, 1,3-cyclohexanedimethylamine, 4,4'-diaminodicyclohexylmethane, isophoronediamine, and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

3. The polyaspartic acid ester according to claim 1, characterized in that, The maleic ester is one or more of diethyl maleate, dibutyl maleate, and dipropyl maleate.

4. The polyaspartic acid ester according to claim 1, characterized in that, The isocyanate is one or more trimers of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate.

5. The polyaspartic acid ester according to claim 1, characterized in that, The reaction temperature for step (1) is 45-55℃ and the reaction time is 192h-288h; the reaction temperature for step (2) is 23-35℃ and the reaction time is 1.5-2h.

6. The polyaspartic acid ester according to claim 1, characterized in that, After step (2), the residual maleate is removed by a thin-film evaporator.

7. The polyaspartic ester according to claim 6, characterized in that, The thin-film evaporator is used to remove maleic esters under vacuum conditions of 140-170℃ and 800-1000Pa.

Images