An imidazoline curing agent and its preparation method

Abstract

The invention discloses an imidazoline curing agent and a preparation method thereof, belonging to the technical field of curing agents, and is prepared from the following raw materials in parts by weight: imidazoline amide: 40-60 parts; fatty acid amide: 20-30 parts; 2,4,6-tris(dimethylaminomethyl)phenol: 1-5 parts; small molecule organic amine: 5-20 parts; benzyl alcohol: 5-30 parts. The present invention reduces the requirement of traditional imidazoline as a curing agent for construction temperature by grafting modification of traditional imidazoline, and combines the special "five-membered heterocycle + long carbon chain" structure of imidazoline to give the coating more excellent performance.

Description

Technical Field

[0001] The present invention relates to the field of curing agents, and in particular to the preparation and application of an imidazoline curing agent. Background Art

[0002] Imidazoline and its derivatives are fine chemical products with excellent performance and have been widely used in the field of corrosion inhibitors at home and abroad. This is due to the fact that the C=N double bond and hydrophilic group in the imidazoline structure can form conjugated or coordinated adsorption with iron atoms, "anchoring" on the surface of the iron substrate, and the hydrophobic side chains are arranged in a directional manner, forming a protective film on the corrosive medium and the surface of the iron substrate, blocking corrosion factors (H2O, Cl - The primary and secondary amine groups in the imidazoline structure can react with the epoxy groups in the epoxy resin, and the tertiary nitrogen atoms in the imidazoline structure can catalyze the ring-opening polymerization of the epoxy groups or catalyze the polymerization of the active functional groups with the epoxy resin. Therefore, in theory, imidazoline can be used as both a curing agent and a curing accelerator for epoxy resins. However, when used as a curing agent, imidazoline has certain temperature requirements. The curing speed is slow under room temperature conditions. Heating or baking is often required for rapid curing, and the application scenarios are greatly limited. Summary of the Invention

[0003] The present invention aims to provide an imidazoline curing agent and a preparation method thereof, which can cure at room temperature and has corresponding anti-corrosion coating properties that meet current testing standards.

[0004] The technical solution of the present invention is achieved as follows:

[0005] The present invention provides an imidazoline curing agent, characterized in that it is prepared from the following raw materials in parts by weight:

[0006] Imidazoline amide: 40-60 parts;

[0007] Fatty acid amide: 20-30 parts;

[0008] 2,4,6-Tris(dimethylaminomethyl)phenol: 1-5 parts;

[0009] Small molecule organic amine: 5-20 parts;

[0010] Benzyl alcohol: 5-30 parts.

[0011] As a further improvement of the present invention, the molecular structure formula of the imidazoline amide is:

[0012] Among them: R structural formula is as follows:

[0013]

[0014]

[0015] n=1, 2, 3, m=2, 3, 4.

[0016] As a further improvement of the present invention, the preparation process of the imidazoline amide is as follows:

[0017] S1: Mix 30-40 parts by weight of an organic solvent and 10-15 parts by weight of phthalic anhydride, and heat to 130-140° C.;

[0018] S2: After all phthalic anhydride is dissolved, add 30-40 parts by weight of imidazoline and react at a temperature of 130-140°C for 3-4 hours;

[0019] The structure of imidazoline is as follows:

[0020]

[0021] Among them: R structural formula is as follows:

[0022]

[0023]

[0024] S3: Add 15-20 parts by weight of polyethylene polyamine, heat to 150-160° C., continue the reaction for 3-4 hours, continue stirring and cool to room temperature to obtain imidazoline amide.

[0025] As a further improvement of the present invention, the polyethylene polyamine in the preparation process of the imidazoline amide is one of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; and the organic solvent is one of xylene and toluene.

[0026] As a further improvement of the present invention, the preparation process of the fatty acid amide is as follows:

[0027] Mix 20-35 parts by weight of polyethylene polyamine and 15-25 parts by weight of an organic solvent, then add 40-60 parts by weight of a fatty acid, heat to 150-160° C., and react for 4-6 hours.

[0028] As a further improvement of the present invention, the polyethylene polyamine in the preparation process of the fatty acid amide is one of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; and the organic solvent is one of xylene and toluene.

[0029] As a further improvement of the present invention, the fatty acid is one of acetic acid, lactic acid, oleic acid, linoleic acid, and linolenic acid.

[0030] As a further improvement of the present invention, the small molecule organic amine is one of hydroxyethylethylenediamine, tetraethylenepentamine, dimethylaminopropylamine, and N-(3-aminopropyl)morpholine.

[0031] As a further improvement of the present invention, the preparation process of the imidazoline curing agent is as follows:

[0032] Mix 40-60 parts by weight of imidazoline amide and 5-30 parts by weight of benzyl alcohol, heat to 30-50° C., and stir for 15-30 minutes. Then, add 20-30 parts by weight of fatty acid amide, 5-20 parts by weight of small molecule organic amine, and 1-5 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol, and continue stirring for 15-30 minutes.

[0033] The present invention has the following beneficial effects:

[0034] This invention grafts imidazoline, imparting superior performance to the anti-corrosion coating through its unique "five-membered heterocyclic ring + long carbon chain" structure. The five-membered heterocyclic ring further enhances the adhesion of the anti-corrosion coating to the substrate, thereby improving the coating's corrosion resistance. The presence of the long carbon chain not only improves the coating's flexibility but also enhances its application performance on wet surfaces through its hydrophobic properties.

[0035] In the present invention, phthalic anhydride is added during the synthesis of imidazoline amide, and the presence of the benzene ring improves the compatibility of the imidazoline amide with the epoxy resin.

[0036] Polyethylene polyamine is added during the synthesis of imidazoline amide, which reduces the active hydrogen equivalent of imidazoline amide on the one hand and reduces the reaction steric hindrance of primary amine on the other hand, thereby increasing the activity of primary amine and enabling rapid curing.

[0037] The present invention adopts the reaction between fatty acid and polyethylene polyamine, which solves the problem of volatility toxicity caused by polyethylene polyamine used as a curing agent alone, and on the other hand, the introduction of carbon chain alleviates the problem of brittle anti-corrosion coating caused by polyethylene polyamine used as a curing agent alone.

[0038] The present invention adds a small amount of small molecule organic amines such as hydroxyethylethylenediamine, tetraethylenepentamine, dimethylaminopropylamine and N-(3-aminopropyl)morpholine to the final formula. In addition to having high reactivity and improving the curing speed of the final curing agent, these small molecule organic amines are less volatile and produce less toxicity. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is the infrared spectrum of the imidazoline prepared in Example 1 of the present invention.

[0041] Figure 2 The infrared spectrum of imidazoline amide prepared in Example 1 of the present invention is DETAILED DESCRIPTION

[0042] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0043] Example 1:

[0044] An imidazoline curing agent, the composition of which is recorded by weight as follows:

[0045] Imidazoline amide: 49 parts;

[0046] Fatty acid amide: 23 parts;

[0047] 2,4,6-Tris(dimethylaminomethyl)phenol (code: DMP-30, the same below): 3 parts;

[0048] Dimethylaminopropylamine: 5 parts;

[0049] Benzyl alcohol: 20 parts.

[0050] An imidazoline curing agent, the preparation method of which is as follows:

[0051] (1) Synthesis of imidazoline amide:

[0052] First, the following raw materials are selected by weight: 37 parts of imidazoline (R is an oleic acid group, n=1, the same below, only for Example 1): 13 parts of phthalic anhydride; 18 parts of tetraethylene pentamine; and 32 parts of xylene. 32 parts of xylene are added to a reactor and stirred. Then, 13 parts of phthalic anhydride are added, and the temperature is set to 130-140°C. After the phthalic anhydride is completely dissolved, 37 parts of imidazoline are added, and the reaction is carried out at a temperature range of 130-140°C for 3-4 hours. Then, 18 parts of tetraethylene pentamine are added, and the temperature is set to 150-160°C, and the reaction is continued for 3-4 hours. After the reaction is completed, heating is stopped, and the mixture is cooled to room temperature with continued stirring to obtain imidazoline amide. Figure 1 、 Figure 2 They are the infrared spectra of imidazoline and imidazoline amide respectively.

[0053] from Figure 1 It can be seen that: 1610cm -1 The peak is very obvious, which is the characteristic peak of imidazoline; 1650cm -1 , 1550cm -1 The characteristic peak of the amide group at is weak, indicating that the imidazoline contains only a small amount of uncyclic amide. Figure 2 It can be seen that with the addition of phthalic anhydride and tetraethylenepentamine, the characteristic peak of imidazoline in the synthesized imidazoline amide still exists (1597cm -1 The presence of benzene ring causes the characteristic peak of imidazoline to shift); however, as the reaction proceeds, phthalic anhydride ring-opening reacts with the terminal primary amine in imidazoline and the terminal primary amine of tetraethylenepentamine, generating a large number of amide groups, which makes the characteristic peak of amide group (1649cm -1 、1546cm -1 ) was significantly enhanced; at the same time, 697cm -1 The characteristic peak of benzene ring appears at . Combined with the amount of water released during the reaction, it can be determined that the synthesized product is imidazoline amide.

[0054] (2) Synthesis of fatty acid amides:

[0055] First, the following raw materials were prepared by weight: oleic acid: 48 parts; tetraethylene pentamine: 32 parts; xylene: 20 parts. 32 parts of tetraethylene pentamine and 20 parts of xylene were added to a reactor, stirred, and then 48 parts of oleic acid were added. The temperature was set to 150-160°C. The reaction was carried out at this temperature for 4-6 hours. After the reaction was completed, heating was stopped, and the mixture was cooled to room temperature with continued stirring to obtain fatty acid amide.

[0056] (3) Preparation of imidazoline curing agent

[0057] 49 parts of imidazoline amide and 20 parts of benzyl alcohol were added to the reactor, stirring was started, the temperature was set to 30-50°C, and stirring was carried out for 15-30 minutes; then 23 parts of fatty acid amide, 5 parts of dimethylaminopropylamine, and 3 parts of DMP-30 were added, stirring was continued for 15-30 minutes, and the final product was obtained by cooling to room temperature.

[0058] The imidazoline curing agent prepared in Example 1 was used as component B and mixed with component A of our company's MC-STE-2 modified epoxy paint in a certain proportion. After board making and curing, a series of performance tests were conducted in accordance with relevant standards. The main results are as follows:

[0059] Table 1 Performance evaluation results of Example 1

[0060]

[0061] Example 2:

[0062] An imidazoline curing agent, the composition of which is recorded in weight percentage:

[0063] Imidazoline amide: 42 parts;

[0064] Fatty acid amide: 30 parts;

[0065] 2,4,6-Tris(dimethylaminomethyl)phenol (code: DMP-30, the same below): 1 part;

[0066] Tetraethylenepentamine: 7 parts;

[0067] Benzyl alcohol: 20 parts.

[0068] An imidazoline curing agent, the preparation method of which is as follows:

[0069] (1) Synthesis of imidazoline amide:

[0070] First, the following raw materials were selected by weight: 34 parts of imidazoline (R is an oleic acid group, n=2, the same below, only for Example 2): 12 parts of phthalic anhydride: 20 parts of triethylenetetramine: 34 parts of xylene. 34 parts of xylene were added to a reactor and stirred. Then, 12 parts of phthalic anhydride were added, and the temperature was set to 130-140°C. After the phthalic anhydride was completely dissolved, 34 parts of imidazoline (prepared in-house) were added, and the reaction was carried out at a temperature range of 130-140°C for 3-4 hours. Then, 20 parts of triethylenetetramine were added, and the temperature was set to 150-160°C, and the reaction was continued for 3-4 hours. After the reaction was completed, heating was stopped, and the mixture was cooled to room temperature with continued stirring to obtain imidazoline amide.

[0071] (2) Synthesis of fatty acid amides:

[0072] First, the following raw materials were prepared by weight: 49 parts lactic acid; 31 parts triethylenetetramine; and 20 parts xylene. 31 parts triethylenetetramine and 20 parts xylene were added to a reactor, stirred, and then 49 parts lactic acid was added. The temperature was set to 150-160°C. The reaction was allowed to proceed at this temperature for 4-6 hours. After the reaction was complete, heating was stopped, and the mixture was allowed to cool to room temperature with continued stirring to obtain the fatty acid amide.

[0073] (3) Preparation of imidazoline curing agent

[0074] 42 parts of imidazoline amide and 20 parts of benzyl alcohol were added to the reactor, stirring was started, the temperature was set to 30-50°C, and stirring was carried out for 15-30 minutes; then 30 parts of fatty acid amide, 7 parts of tetraethylenepentamine, and 1 part of DMP-30 were added, stirring was continued for 15-30 minutes, and the final product was obtained by cooling to room temperature.

[0075] The imidazoline curing agent prepared in Example 2 was used as component B and mixed with component A of our company's MC-STE-2 modified epoxy paint in a certain proportion. After board making and curing, a series of performance tests were conducted in accordance with relevant standards. The main results are as follows:

[0076] Table 2 Performance evaluation results of Example 2

[0077]

[0078]

[0079] Example 3:

[0080] An imidazoline curing agent, the composition of which is recorded in weight percentage:

[0081] Imidazoline amide: 50 parts;

[0082] Fatty acid amide: 25 parts;

[0083] 2,4,6-Tris(dimethylaminomethyl)phenol (code: DMP-30, the same below): 1 part;

[0084] N-(3-aminopropyl)morpholine: 12 parts;

[0085] Benzyl alcohol: 12 parts.

[0086] An imidazoline curing agent, the preparation method of which is as follows:

[0087] (1) Synthesis of imidazoline amide:

[0088] First, the following raw materials were selected by weight: 40 parts of imidazoline (R is a linoleic acid group, n=1, the same below, only for Example 3): 15 parts of phthalic anhydride: 12 parts of diethylenetriamine: 33 parts of xylene. 33 parts of xylene were added to a reactor and stirred, followed by the addition of 15 parts of phthalic anhydride, with the temperature set at 130-140°C. After the phthalic anhydride was completely dissolved, 40 parts of imidazoline (prepared in-house) were added, and the reaction was carried out at a temperature range of 130-140°C for 3-4 hours. 12 parts of diethylenetriamine were then added, and the temperature was set at 150-160°C, and the reaction continued for 3-4 hours. After the reaction was completed, heating was stopped, and the mixture was cooled to room temperature with continued stirring to obtain imidazoline amide.

[0089] (2) Synthesis of fatty acid amides:

[0090] First, the following raw materials were prepared by weight: 50 parts linoleic acid; 20 parts diethylenetriamine; and 30 parts xylene. 20 parts diethylenetriamine and 30 parts xylene were added to a reactor, stirred, and then 50 parts linoleic acid was added. The temperature was set to 150-160°C. The reaction was allowed to proceed at this temperature for 4-6 hours. After the reaction was complete, heating was stopped, and the mixture was allowed to cool to room temperature with continued stirring to obtain the fatty acid amide.

[0091] (3) Preparation of imidazoline curing agent

[0092] 50 parts of imidazoline amide and 12 parts of benzyl alcohol were added to the reactor, stirring was started, the temperature was set to 30-50 ° C, and stirring was carried out for 15-30 minutes; then 25 parts of fatty acid amide, 12 parts of N-(3-aminopropyl)morpholine, and 1 part of DMP-30 were added, stirring was continued for 15-30 minutes, and the final product was obtained by cooling to room temperature.

[0093] The imidazoline curing agent prepared in Example 3 was used as component B and mixed with component A of our company's MC-STE-2 modified epoxy paint in a certain proportion. After board making and curing, a series of performance tests were conducted in accordance with relevant standards. The main results are as follows:

[0094] Table 3 Performance evaluation results of Example 3

[0095]

[0096]

[0097] It can be seen from the above three examples that the imidazoline curing agent obtained by the present invention is mixed with the company's MC-STE-2 modified epoxy paint component A in a certain proportion, and then the drying time, flexibility, impact resistance, adhesion, neutral salt spray resistance, and salt water resistance are tested according to relevant standards. The results show that all are qualified, showing excellent construction and anti-corrosion performance.

[0098] Comparative Example 1:

[0099] A commercially available curing agent (mainly composed of modified imidazoline + polyamide) was mixed with our company's MC-STE-2 modified epoxy paint component A in a certain proportion. The drying time, flexibility, impact resistance, adhesion, neutral salt spray resistance, and salt water resistance were then tested according to relevant standards. The specific results are as follows:

[0100] Table 4 Performance evaluation results of Comparative Example 1

[0101]

[0102]

[0103] As described above, the preferred embodiments have further described the present invention, but are not intended to limit the specific implementation methods of the present invention. For ordinary technicians in the field, other different forms of changes can be made based on the above description without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. An imidazoline curing agent, characterized in that It is prepared from the following raw materials in parts by weight: Imidazoline amide: 40-60 parts; Fatty acid amide: 20-30 parts; 2,4,6-Tris(dimethylaminomethyl)phenol: 1-5 parts; Small molecule organic amine: 5-20 parts; Benzyl alcohol: 5-30 parts; The molecular structure formula of the imidazoline amide is: Among them: R structural formula is as follows: n=1, 2, 3; m=2, 3, 4; The preparation process of the fatty acid amide is as follows: Mix 20-35 parts by weight of polyethylene polyamine I and 15-25 parts by weight of organic solvent I, then add 40-60 parts by weight of fatty acid, heat to 150-160° C., and react for 4-6 hours.

2. An imidazoline curing agent as claimed in claim 1, characterized in that, The preparation process of the imidazoline amide is as follows: S1: Mix 30-40 parts by weight of organic solvent II and 10-15 parts by weight of phthalic anhydride, and heat to 130-140° C.; S2: After all phthalic anhydride is dissolved, add 30-40 parts by weight of imidazoline and react at a temperature of 130-140°C for 3-4 hours; The structure of imidazoline is as follows: Among them: R structural formula is as follows: S3: Add 15-20 parts by weight of polyethylene polyamine II, heat to 150-160° C., continue the reaction for 3-4 hours, continue stirring and cool to room temperature to obtain imidazoline amide.

3. An imidazoline curing agent as claimed in claim 2, characterized in that, The polyethylene polyamine II is one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine; the organic solvent II is one of xylene and toluene.

4. An imidazoline curing agent as claimed in claim 1, characterized in that, The polyethylene polyamine I is one of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; and the organic solvent I is one of xylene and toluene.

5. An imidazoline curing agent as claimed in claim 1, characterized in that, The fatty acid is one of acetic acid, lactic acid, oleic acid, linoleic acid and linolenic acid.

6. An imidazoline curing agent as claimed in claim 1, characterized in that, The small molecule organic amine is one of hydroxyethylethylenediamine, tetraethylenepentamine, dimethylaminopropylamine and N-(3-aminopropyl)morpholine.

7. An imidazoline curing agent as claimed in claim 1, characterized in that, The preparation process of the imidazoline curing agent is as follows: Mix 40-60 parts by weight of imidazoline amide and 5-30 parts by weight of benzyl alcohol, heat to 30-50° C., and stir for 15-30 minutes. Then, add 20-30 parts by weight of fatty acid amide, 5-20 parts by weight of small molecule organic amine, and 1-5 parts by weight of 2,4,6-tris(dimethylaminomethyl)phenol, and continue stirring for 15-30 minutes.

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