An imide secondary amine-based resin and a method for preparing the same

Abstract

The application provides an imide secondary amine-based resin and a preparation method thereof, and relates to the technical field of amino resins. The structure of the imide secondary amine-based resin is wherein X is selected from a divalent organic structure with an average molecular weight of 50-5000 which is left after removing two primary amino groups from a diamine compound and is inert to an isocyanate group at 100 DEG C, R1 and R2 are independently selected from C5-C6 cycloalkyl, C6-C12 substituted cycloalkyl, C1-C20 alkyl or C2-C20 substituted alkyl, and the end groups of R1 and R2 are independently not -OH or -NH2. The imide secondary amine-based resin has better heat resistance, hydrolysis resistance and higher mechanical strength compared with aspartic ester resin.

Description

Technical Field

[0001] This invention belongs to the field of amino resin technology and relates to an imide secondary amine resin and its preparation method. Background Technology

[0002] Aspartic acid ester resin is an alicyclic secondary amine resin prepared by a Michael addition reaction of maleic ester (such as diethyl maleate) and alicyclic amine (such as 4,4'-diaminodicyclohexylmethane or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane). It can be combined with isocyanate curing agents to produce aspartic polyurea. The main chain structure of aspartic acid ester resin provides high weather resistance and excellent mechanical properties for aspartic polyurea. The ester groups on the side chains provide good internal plasticizing and solubilizing effects, ensuring the resin's low viscosity and good flexibility. However, the ester groups on the side chains also result in less outstanding hardness, high-temperature resistance, and chemical resistance, limiting its application under harsh conditions. Furthermore, the ester groups have poor stability, exhibiting instability in aqueous environments and at high temperatures, leading to significant weight loss, gloss loss, and shrinkage under these conditions.

[0003] Therefore, it is necessary to modify aspartic ester resin to improve its water resistance, high temperature resistance and other properties, thereby improving the hardness, high temperature resistance, chemical resistance and water resistance of aspartic polyurea. Summary of the Invention

[0004] Imide structures exhibit good stability, water resistance, and high-temperature resistance. Existing technologies have reported the use of maleimide to replace maleic esters in the preparation of aspartic resins; however, due to the limitations of the maleimide structure, the structures of alicyclic secondary amine resins are limited, making it difficult to obtain alicyclic secondary amine resins with diverse structures. To address the above technical problems, this invention provides an imide secondary amine resin and its preparation method.

[0005] The technical solution of the present invention is as follows:

[0006] An imide secondary amine resin has the structure shown in formula (1).

[0007]

[0008] Wherein, X is selected from the divalent organic structure of a diamine compound after the removal of two primary amino groups, which is reactive with the isocyanate group at 100°C and has an average molecular weight of 50-5000. R1 and R2 are individually selected from C5-C6 cycloalkyl, C6-C12 substituted cycloalkyl, C1-C20 alkyl or C2-C20 substituted alkyl groups, and the terminal groups of R1 and R2 are not individually -OH or -NH2.

[0009] Preferably, R1 and R2 are individually selected from C5-C6 cycloalkyl, C6-C12 oxa-substituted cycloalkyl, C6-C12 nitro-substituted cycloalkyl, or C6-C12 thia-substituted cycloalkyl.

[0010] Preferably, R1 and R2 are individually selected from C2-C18 hydrocarbon groups or C3-C18 substituted hydrocarbon groups.

[0011] A method for preparing an imide secondary amine resin according to any of the above technical solutions involves adding an aspartic acid ester resin to a reaction vessel, adding a catalyst, heating to 80-150°C, adding a monofunctional primary amine compound, continuing the reaction at a constant temperature and continuously removing the generated alcohol from the reaction system until the aspartic acid ester resin is completely reacted, thereby obtaining the imide secondary amine resin.

[0012] The general structural formula of the monofunctional primary amine compound is shown in formula (2) or (3) below, or the monofunctional primary amine compound is a combination of the structures shown in formula (2) and (3).

[0013] R1NH2(2)

[0014] R2NH2(3)

[0015] The meanings of R1 and R2 are as described above.

[0016] Preferably, the catalyst is selected from one or a combination of two or more of C8-C18 fatty acids, benzotriazoles, and substituted benzotriazoles.

[0017] Preferably, the catalyst is selected from 1-hydroxybenzotriazole.

[0018] Preferably, the weight of the catalyst is 0.1-0.5% of the weight of the aspartic ester resin.

[0019] Preferably, the molar ratio of the aspartic acid ester resin to the monofunctional primary amine compound is 1:1.8-2.5.

[0020] More preferably, the molar ratio is 1:1.9-2.3.

[0021] Preferably, the aspartic acid ester resin reaction is completed until the ester groups in the reaction system disappear as determined by FT-IR testing.

[0022] The beneficial effects of this invention are:

[0023] (1) The present invention can easily obtain imide secondary amine resin by imidizing the ester group of aspartic acid ester resin with a monofunctional primary amine compound. Moreover, the conversion rate is high and the aspartic acid ester resin raw material can be completely reacted and converted into imide secondary amine resin.

[0024] (2) The imide secondary amine resin of the present invention can be directly used as commercially available aspartic acid ester resin, and the raw materials are easy to obtain.

[0025] (3) The imide secondary amine resin of the present invention can be obtained by using different monofunctional primary amine compounds, thereby obtaining imide secondary amine resins with different end group structures. The preparation method is more flexible and can obtain imide secondary amine resins with different structures and different properties. Detailed Implementation

[0026] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0027] In order to provide an imide secondary amine resin with a flexible adjustable structure, the present invention provides an imide secondary amine resin having the structure shown in formula (1).

[0028]

[0029] Wherein, X is selected from the divalent organic structure of a diamine compound after the removal of two primary amino groups, which is reactive with the isocyanate group at 100℃ and has an average molecular weight of 50-5000. R1 and R2 are individually selected from C5-C6 cycloalkyl, C6-C12 substituted cycloalkyl, C1-C20 alkyl or C2-C20 substituted alkyl groups. The terminal groups of R1 and R2 are not -OH or -NH2.

[0030] In the above structure (1) of the present invention, the imide structure replaces the ester group of the existing aspartic acid ester at both ends of the imide secondary amine resin structure. The imide secondary amine resin has better hydrolysis resistance, high temperature resistance and other properties compared with aspartic acid ester. Moreover, since the imide is a rigid structure, it can also improve the mechanical strength of the polyurea obtained after the imide secondary amine resin and the curing agent are cured.

[0031] In the structure of formula (1) above, if the end groups of R1 and R2 are hydroxyl or primary amino groups, the operating time after mixing with the curing agent will be shorter. Therefore, neither R1 nor R2 has an end group of -OH or -NH2.

[0032] In this invention, the diamine compound is not particularly limited and can be a diamine compound commonly used in the field of aspartic acid ester resins, such as 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-cyclopentanediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, polyetheramine, etc. Polyetheramines can be purchased directly from the market, such as polyetheramine D-230, polyetheramine D-400, polyetheramine D-2000, polyetheramine ED-600, polyetheramine ED-900, polyetheramine T-403, polyetheramine T-5000, etc., but are not limited to those listed above.

[0033] In a preferred embodiment of the present invention, R1 and R2 are individually selected from C5-C6 cycloalkyl, C6-C12 oxa-substituted cycloalkyl, C6-C12 aza-substituted cycloalkyl, or C6-C12 thia-substituted cycloalkyl. In the present invention, R1 and R2 can be the same or different; for example, R1 and R2 can be cyclohexyl, cycloalkyl, 2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2-methylcyclopentyl, etc.

[0034] In a preferred embodiment of the present invention, R1 and R2 are individually selected from C2-C18 hydrocarbon groups or C3-C18 substituted hydrocarbon groups. For example, R1 and R2 can be butyl, isobutyl, 1-hexyl, isopropyl, isooctyl, lauryl, stearyl, 9-octadecenyl, -CH2CH2OCH3, -CH2CH2OCH2CH3, or polyethylene glycol segment -(CH2CH2O). a CH3, polyether segment -(CH2CH2O) m (CH2CHCH3O) n CH3, etc., a>0, m≥0, n≥0, m+n>0. When R1 and / or R2 are hydrophilic polyether segments, such as polyethylene glycol segments, the imide secondary amine resin of the present invention can be endowed with good hydrophilic or hydrophilic-lipophilic properties, and can be used as a hydrophilic resin, surfactant, or emulsifier.

[0035] To provide greater flexibility in the preparation method, the present invention provides a method for preparing the imide secondary amine resin described in any of the above technical solutions. The method involves adding aspartic acid ester resin to a reaction vessel, adding a catalyst, heating to 80-150°C, adding a monofunctional primary amine compound, continuing the reaction at a constant temperature, and continuously removing the generated alcohol from the reaction system until the aspartic acid ester resin has completely reacted, thereby obtaining the imide secondary amine resin of the present invention.

[0036] The general structural formula of monofunctional primary amine compounds is shown in formula (2) or (3) below, or the monofunctional primary amine compound is a combination of the structures shown in formula (2) and (3).

[0037] R1NH2(2)

[0038] R2NH2(3)

[0039] The meanings of R1 and R2 are as described above.

[0040] In the preparation method of the imide secondary amine resin of the present invention, commercially available aspartic acid ester resin (such as F420, F520, F524, etc. from Feiyang Junyan Company) can be directly used to react with a monofunctional primary amine compound under the action of a catalyst to obtain the resin. Using the same monofunctional primary amine compound, imide secondary amine resin with the same end group structure can be obtained; using different monofunctional primary amine compounds, imide secondary amine resin with different end group structures can be obtained. In specific operation, one monofunctional primary amine compound can be added first to react, and then another monofunctional primary amine compound can be added to react.

[0041] In this invention, the combination of structures shown in formulas (2) and (3) is not particularly limited in terms of molar ratio or weight ratio, and can be selected based on the properties of the obtained imide secondary amine resin. For example, the molar ratio of the structures shown in formulas (2) and (3) can be any value among 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, etc., without any particular limitation.

[0042] In a preferred embodiment of the present invention, the catalyst is selected from one or a combination of two or more of C8-C18 fatty acids, benzotriazoles, and substituted benzotriazoles. Using the above catalyst can accelerate the imide reaction. Furthermore, by continuously removing the generated alcohol from the system (the removal method can be heating the alcohol above its boiling point to distill it off or continuously passing gas to remove the generated alcohol), the imide reaction is promoted to completion. For example, the C8-C18 fatty acid can be lauric acid, stearic acid, etc., and the substituted benzotriazole can be 1-hydroxybenzotriazole, etc.

[0043] In a preferred embodiment of the present invention, the catalyst is selected from 1-hydroxybenzotriazole.

[0044] In a preferred embodiment of the present invention, the weight of the catalyst is 0.1-0.5% of the weight of the aspartic ester resin. For example, the weight of the catalyst is any value among 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5% of the weight of the aspartic ester resin, without any particular limitation.

[0045] In a preferred embodiment of the present invention, the molar ratio of aspartic acid ester resin to monofunctional primary amine compound is 1:1.8-2.5. A molar ratio of aspartic acid ester resin to monofunctional primary amine compound within the above range can promote the conversion of most or all of the ester groups to imide. For example, the molar ratio of aspartic acid ester resin to monofunctional primary amine compound can be any value from 1:1.8, 1:1.85, 1:1.9, 1:1.95, 1:2, 1:2.05, 1:2.1, 1:2.15, 1:2.2, 1:2.25, 1:2.3, 1:2.35, 1:2.4, 1:2.45, 1:2.5, etc., without particular limitation. More preferably, the molar ratio is 1:1.9-2.3. Or even more preferably, the molar ratio is 1:2.0-2.2.

[0046] In a preferred embodiment of the present invention, the aspartic ester resin reaction is considered complete when the ester groups in the reaction system disappear as determined by FT-IR testing. FT-IR can sensitively detect ester groups in the reaction system, and when FT-IR detects the absence of ester groups in the reaction system, the aspartic ester resin reaction can be considered complete.

[0047] The technical solutions of the present invention will be further described and explained below with reference to various embodiments.

[0048] Example 1

[0049] 1 mol of aspartic resin F420 (Feiyang Junyan Company) was added to a 1 L four-necked flask. Stirring was started, and 0.6 g of 1-hydroxybenzotriazole was added and dissolved completely. The temperature was raised to 120 °C, and 2 mol of oleylamine was slowly added. Nitrogen gas was maintained through the reaction system, and the ethanol produced in the reaction was carried away by a distillation head. Samples were taken and the ester absorption peak (1730–1735 cm⁻¹) was detected using FT-IR. -1 The reaction proceeds until the ester absorption peak disappears in the reaction system. The pressure is reduced to -0.099 MPa and a vacuum is drawn to remove low-boiling substances. After cooling, a brownish-red transparent slightly turbid viscous liquid is obtained, which is the imide secondary amine resin.

[0050] In the imide secondary amine resin of this embodiment, in the structure of the above formula (1), R1 and R2 are both 9-octadecenyl.

[0051] Example 2

[0052] 1 mol of aspartic resin F420 was added to a 1 L four-necked flask. Stirring was started, and 0.8 g of 1-hydroxybenzotriazole was added and dissolved completely. The temperature was raised to 90 °C, and 2.2 mol of 1-hexylamine was slowly added. Nitrogen gas was maintained through the reaction system, and the ethanol produced in the reaction was carried away by a distillation head. Samples were taken and the ester absorption peak (1730–1735 cm⁻¹) was detected using FT-IR. -1The reaction proceeds until the ester absorption peak disappears in the reaction system. The pressure is reduced to -0.099 MPa and a vacuum is drawn to remove low-boiling substances. After cooling, a brownish-red transparent slightly turbid viscous liquid is obtained, which is the imide secondary amine resin.

[0053] In the imide secondary amine resin of this embodiment, in the structure of the above formula (1), R1 and R2 are both 1-hexyl.

[0054] Example 3

[0055] 1 mol of aspartic resin F420 was added to a 1 L four-necked flask. Stirring was started, and 0.8 g of 1-hydroxybenzotriazole was added and dissolved completely. The temperature was raised to 120 °C, and 1 mol of 1-hexylamine was slowly added. Nitrogen gas was maintained through the reaction system, and the ethanol produced in the reaction was carried away by a distillation head. Samples were taken and the ester absorption peak (1730–1735 cm⁻¹) was detected using FT-IR. -1 The reaction proceeded until the ester group absorption peak in the reaction system remained unchanged. Then, 1 mol of terminal amine-terminated polyethylene glycol NH2CH2CH2(OCH2CH2) was added. 12.5 OCH3 was reacted until the ester absorption peak disappeared in the reaction system. The pressure was reduced to -0.099 MPa and vacuum was applied to remove low-boiling substances. After cooling, a brownish-red transparent slightly turbid viscous liquid was obtained, which is the imide secondary amine resin.

[0056] In the imide secondary amine resin of this embodiment, in the structure of formula (1) above, R1 is 1-hexyl and R2 is -CH2CH2(OCH2CH2). 12.5 OCH3.

[0057] The above-mentioned secondary imide resin was added to pure water to prepare 0.5 wt% and 1 wt% aqueous solutions, respectively. The aqueous solutions were nearly colorless and transparent, and the surface tensions measured using the platinum plate method were 25.2 mN / m and 24.5 mN / m, respectively. This indicates that the secondary imide resin obtained in this embodiment has good surface activity.

[0058] The above-mentioned imide secondary amine resin was added to pure water to prepare a 10wt% aqueous solution. The aqueous solution was opaque, and resin was present at the bottom after standing for 2 days. This indicates that the hydrophilicity of the imide secondary amine resin in this embodiment is insufficient to make the imide secondary amine resin a hydrophilic resin.

[0059] Example 4

[0060] 1 mol of aspartic resin F420 was added to a 1 L four-necked flask. Stirring was started, and 1.0 g of 1-hydroxybenzotriazole was added and dissolved completely. The temperature was raised to 140 °C, and 2 mol of the terminal amine polyethylene glycol from Example 3 was slowly added. Nitrogen gas was maintained through the reaction system, and the ethanol produced in the reaction was carried away by a distillation head. Samples were taken and the ester absorption peak (1730–1735 cm⁻¹) was detected using FT-IR.-1 The reaction proceeds until the ester absorption peak disappears in the reaction system. The pressure is reduced to -0.099 MPa and a vacuum is drawn to remove low-boiling substances. After cooling, a brownish-red transparent slightly turbid viscous liquid is obtained, which is the imide secondary amine resin.

[0061] In the imide secondary amine resin of this embodiment, in the structure of formula (1) above, both R1 and R2 are -CH2CH2(OCH2CH2). 12.5 OCH3.

[0062] The above-mentioned imide secondary amine resin was added to pure water to prepare a 40wt% aqueous solution. The aqueous solution was semi-transparent, indicating good solubility. After standing for 2 months, no abnormal phenomena such as precipitation or oil separation were observed in the aqueous solution.

[0063] Example 5

[0064] 1 mol of aspartic resin F520 (Feiyang Junyan Company) was added to a 1 L four-necked flask. Stirring was started, and 1.0 g of 1-hydroxybenzotriazole was added and dissolved completely. The temperature was raised to 120 °C, and 2.1 mol of 1-laurhodium was slowly added. Nitrogen gas was maintained through the reaction system, and the ethanol produced in the reaction was carried away by a distillation head. Samples were taken and the ester absorption peak (1730–1735 cm⁻¹) was detected using FT-IR. -1 The reaction proceeds until the ester absorption peak disappears in the reaction system. The temperature is raised to 150℃ and the pressure is reduced to -0.099MPa to remove low-boiling substances. After cooling, a brownish-red transparent slightly turbid viscous liquid is obtained, which is the imide secondary amine resin.

[0065] In the imide secondary amine resin of this embodiment, R1 and R2 are both lauryl groups in the structure of formula (1) above.

[0066] Example 6

[0067] 1 mol of aspartic resin F520 was added to a 1 L four-necked flask. Stirring was started, and 1.0 g of 1-hydroxybenzotriazole was added and dissolved completely. The temperature was raised to 120 °C, and 1 mol of 1-laurhodium was slowly added. Nitrogen gas was maintained through the reaction system, and the ethanol produced in the reaction was carried away by a distillation head. Samples were taken and the ester absorption peak (1730–1735 cm⁻¹) was detected using FT-IR. -1 The reaction proceeded until the ester absorption peak in the reaction system remained unchanged. Then, 1 mol of terminal amine polyether NH2CH2CH2(OCH2CH2) was added. 20.3 (OCH2CHCH3) 6.8 OCH3 was heated to 140℃ and reacted until the ester absorption peak in the reaction system disappeared. The pressure was reduced to -0.099MPa and vacuum was applied to remove low-boiling substances. After cooling, a brownish-red transparent slightly turbid viscous liquid was obtained, which is the imide secondary amine resin.

[0068] In the imide secondary amine resin of this embodiment, in the structure of formula (1) above, R1 is 1-octyl and R2 is -CH2CH2(OCH2CH2). 20.3 (OCH2CHCH3) 6.8 OCH3.

[0069] The above-mentioned secondary imide resin was added to pure water to prepare 0.5 wt% and 1 wt% aqueous solutions, respectively. The aqueous solutions were nearly colorless and transparent, and the surface tensions measured using the platinum plate method were 24.8 mN / m and 24.3 mN / m, respectively. This indicates that the secondary imide resin obtained in this embodiment has good surface activity.

[0070] Performance testing

[0071] Examples 1, 2, and 5, F420 resin, and F520 resin were respectively mixed with an isocyanate curing agent (the isocyanate curing agent is composed of an adduct curing agent prepared from 3% HDI trimer, 10% HMDI, and 87% IPDI with polyether polyol) at a total molar content of secondary amine and hydroxyl groups to NCO molar amount of 1:1.05. The premix was made into a 0.5 mm thick coating and cured at 35±2℃ for 15 days. The tensile strength and heat distortion temperature were tested. The higher the heat distortion temperature, the better the heat resistance.

[0072] The above premix was used to form a film with a thickness of 0.2 mm on a clean tinplate surface. The film was cured at 35±2℃ for 15 days, and its retention time after boiling in 100℃ water was tested. The longer the boiling time, the better the hydrolysis resistance.

[0073] The results are shown in Table 1 below.

[0074] Tensile strength / MPa Heat distortion temperature / ℃ Boiling time at 100℃ Example 1 17.2 155 6h Example 2 17.9 160 5.5h F420 resin 15.4 148 2h Example 5 16.3 160 7.5h F520 resin 14.8 154 3.5h

[0075] As can be seen from the data results in Table 1 above, the imide secondary amine resin of the present invention has higher tensile strength, heat distortion temperature and hydrolysis resistance after curing compared with the existing aspartic resin.

[0076] Based on the results of Examples 3, 4 and 6, it is demonstrated that the properties of the imide secondary amine resin of the present invention can be flexibly adjusted by modifying the structure at both ends.

[0077] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an imide secondary amine resin, characterized in that, Aspartic acid ester resin is added to a reaction vessel, a catalyst is added, the temperature is raised to 80-150℃, a monofunctional primary amine compound is added, the reaction is continued at a constant temperature and the alcohol produced is continuously removed from the reaction system until the aspartic acid ester resin is completely reacted, thus obtaining the imide secondary amine resin. The general structural formula of the monofunctional primary amine compound is shown in formula (2) or (3) below, or the monofunctional primary amine compound is a combination of the structures shown in formula (2) and (3). R1NH2(2) R2NH2(3) Wherein, R1 and R2 are individually selected from C5-C6 cycloalkyl, C6-C12 substituted cycloalkyl, C1-C20 alkyl or C2-C20 substituted alkyl, and the terminal groups of R1 and R2 are not individually -OH or -NH2; The imide secondary amine resin has the structure shown in formula (1). （1） Wherein, X is selected from the divalent organic structure of a diamine compound after the removal of two primary amino groups, which is reactive with the isocyanate group at 100℃ and has an average molecular weight of 50-5000; R3 is selected from R1 or R2; and R4 is selected from R1 or R2.

2. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, R1 and R2 are individually selected from C5-C6 cycloalkyl, C6-C12 oxa-substituted cycloalkyl, C6-C12 azia-substituted cycloalkyl, or C6-C12 thia-substituted cycloalkyl.

3. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, R1 and R2 are individually selected from C2-C18 hydrocarbon groups or C3-C18 substituted hydrocarbon groups.

4. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, R1 and R2 are different; When adding the monofunctional primary amine compound, R1NH2 is added first to react, and then R2NH2 is added to react. Alternatively, when adding the monofunctional primary amine compound, R2NH2 is added first to react, followed by R1NH2 to react.

5. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, The catalyst is selected from one or a combination of two or more of C8-C18 fatty acids, benzotriazoles, and substituted benzotriazoles.

6. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, The catalyst is selected from 1-hydroxybenzotriazole.

7. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, The catalyst is 0.1-0.5% of the weight of the aspartic acid ester resin.

8. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, The molar ratio of the aspartic acid ester resin to the monofunctional primary amine compound is 1:1.8-2.

5.

9. The method for preparing the imide secondary amine resin according to claim 8, characterized in that, The molar ratio is 1:1.9-2.

3.

10. The method for preparing the imide secondary amine resin according to claim 1, characterized in that, The reaction of the aspartic acid ester resin was completed until the ester groups disappeared in the FT-IR test reaction system.

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