Polyamide epoxy resin curing agent, preparation method and application

Abstract

The application discloses a polyamide epoxy resin curing agent, a preparation method and application. The curing agent is prepared by reacting raw materials including the following components by weight: a) hydrophobic amine 1-40 parts; b) water-soluble amine 0-30 parts; c) carboxyl or ester group-containing compound 10-40 parts; d) epoxy group-containing polyether 5-40 parts; and e) epoxy group-containing resin / compound 0-40 parts. The application uses hydrophobic amine as a raw material, and adjusts the formula composition to obtain an epoxy resin curing agent with good water solubility. The curing agent has improved water resistance and corrosion resistance when applied to water-based paint based on reduced hydrophilic segments. Meanwhile, the epoxy resin curing agent shows a clear solution form before or after water dispersion, is more conducive to long-term stable storage without flocculation, and has better product application.

Description

Technical Field

[0001] This invention relates to an epoxy resin curing agent, and more particularly to a polyamide-based epoxy resin curing agent, its preparation method, and its application. Background Technology

[0002] Epoxy resin is widely used in civil engineering, electronics, aerospace, automotive machinery and other fields, and is an important part of national production. However, epoxy resin itself is a thermoplastic linear structure with no obvious melting point. It softens and gradually melts when heated, becoming sticky. It is insoluble in water and does not harden on its own. Therefore, it has almost no value for use on its own. Only when it reacts with a curing agent to form a three-dimensional network structure of polymer materials does it have application value.

[0003] As people become increasingly environmentally conscious, epoxy resin coatings are gradually shifting from oil-based to water-based. However, the performance differences between water-based and oil-based epoxy coatings limit their application and development. The reason for this is that most water-based epoxy curing agents are currently made from water-soluble amines. However, the overly hydrophilic nature of amine compounds often leads to slow water evaporation during curing, resulting in a strong water retention capacity in the paint film. The presence of a large amount of water affects the film-forming process, causing numerous defects in the paint film and consequently reducing the water resistance and corrosion resistance of the water-based coating.

[0004] Therefore, how to provide epoxy resin curing agents with good water solubility and excellent water and corrosion resistance is a technical problem that major manufacturers are currently committed to solving. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention first proposes a polyamide-based epoxy resin curing agent. This invention uses hydrophobic amines as raw materials and, through adjusting the formulation, obtains an epoxy resin curing agent with good water solubility. Based on a reduction in hydrophilic segments, this curing agent exhibits improved water resistance and corrosion resistance when applied to water-based coatings. Furthermore, the epoxy resin curing agent remains a clear solution before and after water dispersion, which is more conducive to long-term stable storage without flocculation, resulting in better product applicability.

[0006] Based on a second aspect of the present invention, a method for preparing a polyamide-based epoxy resin curing agent is also provided, which can easily produce an epoxy resin curing agent that simultaneously possesses excellent water resistance, corrosion resistance, and storage stability.

[0007] Based on a third aspect of the present invention, the application of a polyamide epoxy resin curing agent in water-based coatings is also provided.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A polyamide-based epoxy resin curing agent is prepared by reacting the following raw materials in parts by weight:

[0010]

[0011] In a preferred embodiment of the present invention, the hydrophobic amine is selected from diaminodicyclohexylmethane and its derivatives, dimethyldiaminodicyclohexylmethane and its derivatives, or a mixture of one or more of these. Specifically, diaminodicyclohexylmethane is, for example, 4,4'-diaminodicyclohexylmethane, 2,4'-diaminodicyclohexylmethane, etc.; derivatives of diaminodicyclohexylmethane are, for example, tricyclic derivatives of diaminodicyclohexylmethane, tetracyclic derivatives of diaminodicyclohexylmethane, and other polyfunctional polyamines or mixtures thereof, such as WANAMINE2300, WANAMINE2400, etc.; dimethyldiaminodicyclohexylmethane is, for example, 3,3'-dimethyl-4,4-diaminodicyclohexylmethane, etc.; and derivatives of dimethyldiaminodicyclohexylmethane are, for example, polyfunctional polyamines (containing tricyclic derivatives or more than three-cyclic derivatives of dimethyldiaminodicyclohexylmethane) commercially available from various chemical plants.

[0012] In a preferred embodiment of the present invention, the water-soluble amine is selected from at least one of aliphatic amines, alicyclic amines, and aromatic amines, preferably one or more of triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyetheramine, isophorone diamine, 1,3-cyclohexanedimethylamine, N-aminoethylpiperazine, N-aminopropylcyclohexylamine, and m-phenylenediamine.

[0013] In a preferred embodiment of the present invention, the carboxyl or ester-containing compound is selected from one or more of oleic acid, fatty acids, dimer acids, trimer acids, methyl oleate, ethyl oleate, methyl fatty acid, epoxidized methyl fatty acid, ethyl fatty acid, dimer acid methyl ester, and trimer acid methyl ester.

[0014] In a preferred embodiment of the present invention, the epoxy polyether is selected from at least one of polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether, which have a weight average molecular weight of 100-10000.

[0015] In a preferred embodiment of the present invention, the epoxy resin / compound is selected from one or more of epoxy resin E51, epoxy resin E44, epoxy resin E20, benzyl glycidyl ether, phenyl glycidyl ether, butyl glycidyl ether, C12-C14 alkyl glycidyl ether, 1,4-butanediol diglycidyl ether, and 1,2-ethylene glycol diglycidyl ether, preferably at least one of epoxy resin E51, benzyl glycidyl ether, and C12-C14 glycidyl ether.

[0016] This invention also provides a method for preparing a polyamide-based epoxy resin curing agent as described above, comprising the following steps:

[0017] 1) Add components a), b), and c) to the reaction vessel, heat the mixture to react, and obtain the intermediate product;

[0018] 2) After cooling the intermediate product obtained in step 1), add components d) and e) to continue the reaction. After the reaction, cool down to obtain the epoxy resin curing agent.

[0019] In a preferred embodiment of the present invention, the reaction conditions in step 1) are as follows: after reacting at 70-100°C with stirring for 1-2 hours, the temperature is raised to 100-270°C and the reaction continues for 0.5-10 hours.

[0020] In a preferred embodiment of the present invention, the reaction conditions in step 2) are: reaction at 70-100°C with stirring for 1-4 hours.

[0021] The present invention also provides the application of the polyamide epoxy resin curing agent as described above or the polyamide epoxy resin curing agent prepared by the method described above in water-based coatings.

[0022] The water-based coating is composed of component A, which contains epoxy emulsion, and component B, which contains epoxy curing agent. The formulation of component A, by weight, may be, for example, 16-18 parts water, 24-48 parts filler, 1-2 parts leveling and wetting agent, 1-2 parts defoamer, and 40-45 parts epoxy emulsion.

[0023] The filler may be, for example, but not limited to, one or more of the following: dispersant, barium sulfate, titanium dioxide, and zinc phosphate; wherein the dispersant may be BYK190, BYK180, TEGO-760w, etc.

[0024] The leveling and wetting agent may be BYK-346, TEGO-4100, TEGO-270, etc.;

[0025] The defoamer may be BYK019, TEGO-810, etc.

[0026] The epoxy emulsion is an aqueous epoxy emulsion prepared from epoxy resin, such as Wantipro0903 or Wantipro0906 from Wanhua Chemical Group Co., Ltd., and WB6001 aqueous epoxy emulsion from Dow Chemical Company. The solid content of the epoxy emulsion is 45-55%.

[0027] The amount of component B is 1-50% of the total mass of component A, preferably 5-20%. Component B can be any polyamide epoxy resin curing agent described above or any polyamide epoxy resin curing agent prepared by any of the methods described above, or it can be a diluted product of the aforementioned polyamide epoxy resin curing agent after being dispersed in water.

[0028] Methods for preparing waterborne coatings from waterborne epoxy resin curing agents are well known in the art, and are illustrated by examples, but are not limited to:

[0029] Weigh deionized water, dispersant, leveling and wetting agent, and defoamer into a grinder and disperse them evenly at 500-800 rpm. Then, weigh out barium sulfate, titanium dioxide, and zinc phosphate in sequence and mix evenly. Next, adjust the grinding speed to 2000-2500 rpm. When the slurry fineness is below 40 μm, reduce the speed to 500-800 rpm. Then, add epoxy emulsion and stir evenly to obtain water-based coating component A. Then, mix component A and component B evenly according to the formula to obtain the water-based coating.

[0030] This invention incorporates a hydrophobic amine containing an alicyclic structure into the structure of an epoxy resin curing agent. While maintaining the flexibility and toughness of the flexible chain, it significantly improves the product's rigidity, thereby enhancing its water resistance and corrosion resistance. This makes it applicable to water-based flooring and water-based anti-corrosion coatings for steel structures, demonstrating significant application value. Furthermore, this solution unexpectedly reveals that a clear and transparent hydrophilic curing agent can be obtained under the provided formulation conditions, further improving the product's storage stability. In addition, the water-based epoxy resin curing agent provided by this invention can be used alone or in combination with other epoxy resin curing agents, offering a wide range of applications. Detailed Implementation

[0031] 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.

[0032] The names, abbreviations, and sources of the main chemicals used in the embodiments of this invention are shown in Table 1. Unless otherwise specified, all reagents used are of analytical grade.

[0033] Table 1. Information on Main Raw Materials

[0034]

[0035]

Example 1

[0036] Polyamide epoxy resin curing agent A was prepared according to the following method:

[0037] (1) Add 10g of HMDA, 10g of diethylenetriamine and 30g of dimer acid to a three-necked reaction vessel, heat to 70°C, stir and react for 1h, then raise the temperature to 140°C and stir and react for 10h.

[0038] (2) Cool the product from step (1) to 70°C, add 25g of polyethylene glycol diglycidyl ether and 25g of benzyl glycidyl ether while stirring, and continue the reaction. Stir the reaction at 70°C for 4 hours to obtain the epoxy resin curing agent.

[0039]

Example 2

[0040] Polyamide epoxy resin curing agent B was prepared according to the following method:

[0041] (1) Add 40g of HMDA and 20g of dimer acid to a three-necked reaction vessel, heat to 100℃, stir and react for 2h, then raise the temperature to 250℃ and stir and react for 5h.

[0042] (2) Cool the product from step (1) to 70°C, add 40g of polyethylene glycol diglycidyl ether while stirring, and continue the reaction. Stir the reaction at 100°C for 2 hours to obtain the epoxy resin curing agent.

[0043]

Example 3

[0044] Polyamide epoxy resin curing agent C is prepared according to the following method:

[0045] (1) Add 25g of HMDA, 20g of triethylenetetramine and 10g of dimer acid to a three-necked reaction vessel, heat to 85°C, stir and react for 2h, then raise the temperature to 190°C and stir and react for 3h.

[0046] (2) Cool the product from step (1) to 85°C, add 25g of polyethylene glycol diglycidyl ether and 20g of epoxy resin E51 while stirring, and continue the reaction. Stir the reaction at 85°C for 1 hour to obtain the epoxy resin curing agent.

[0047]

Example 4

[0048] Polyamide epoxy resin curing agent D is prepared according to the following method:

[0049] (1) Add 5g of HMDA, 25g of triethylenetetramine and 25g of dimer acid to a three-necked reaction vessel, heat to 80°C, stir and react for 1 hour, then raise the temperature to 200°C and stir and react for 5 hours.

[0050] (2) Cool the product from step (1) to 90°C, add 35g of polypropylene glycol diglycidyl ether and 10g of C12-C14 alkyl glycidyl ether while stirring, and continue the reaction. Stir the reaction at 90°C for 2 hours to obtain the epoxy resin curing agent.

[0051]

Example 5

[0052] Polyamide epoxy resin curing agent E is prepared according to the following method:

[0053] (1) Add 30g of WANAMINE2300, 15g of triethylenetetramine and 30g of dimer acid to a three-necked reaction vessel, heat to 180°C, stir and react for 1 hour, then raise the temperature to 200°C and stir and react for 5 hours.

[0054] (2) Cool the product from step (1) to 80°C, add 20g of polyethylene glycol diglycidyl ether and 20g of C12-C14 glycidyl ether while stirring, and continue the reaction. Stir the reaction at 80°C for 2 hours to obtain the epoxy resin curing agent.

[0055]

Example 6

[0056] Polyamide epoxy resin curing agent F was prepared according to the following method:

[0057] (1) Add 15g of WANAMINE2400, 15g of tetraethylenepentamine and 20g of dimer acid to a three-necked reaction vessel, heat to 150°C, stir and react for 1 hour, then raise the temperature to 220°C and stir and react for 3 hours.

[0058] (2) Cool the product from step (1) to 100°C, add 30g of polyethylene glycol diglycidyl ether and 10g of phenyl glycidyl ether while stirring, and continue the reaction. Stir the reaction at 100°C for 4 hours to obtain the epoxy resin curing agent.

[0059]

Example 7

[0060] Polyamide epoxy resin curing agent G is prepared according to the following method:

[0061] (1) Add 20g of MACM, 20g of m-phenylenediamine and 20g of fatty acid methyl ester to a three-necked reaction vessel, heat to 150℃, stir and react for 2h, then raise the temperature to 220℃ and stir and react for 5h.

[0062] (2) Cool the product from step (1) to 90°C, add 10g of polyethylene glycol diglycidyl ether and 10g of epoxy resin E51 while stirring, and continue the reaction. Stir the reaction at 90°C for 3 hours to obtain the epoxy resin curing agent.

[0063]

Example 8

[0064] Polyamide epoxy resin curing agent H was prepared according to the following method:

[0065] (1) Add 35g of HMDA, 20g of cyclohexanedimethylamine and 10g of epoxidized fatty acid methyl ester to a three-necked reaction vessel, heat to 180℃, stir and react for 2h, then raise the temperature to 230℃ and stir and react for 4h.

[0066] (2) Cool the product from step (1) to 80°C, add 30g of polyethylene glycol diglycidyl ether and 10g of butyl glycidyl ether while stirring, and continue the reaction. Stir the reaction at 80°C for 2 hours to obtain the epoxy resin curing agent.

[0067] Comparative Example 1

[0068] Epoxy resin curing agent Q1 was prepared using essentially the same method as in Example 1, except that HMDA was not added and the amount of diethylenetriamine was changed to 20g.

[0069] Comparative Example 2

[0070] Epoxy resin curing agent Q2 was prepared using essentially the same method as in Example 1, except that the amount of dimer acid added was replaced with 45g.

[0071] Comparative Example 3

[0072] Epoxy resin curing agent Q3 was prepared using essentially the same method as in Example 1, except that diethylenetriamine was not added.

[0073] Comparative Example 4

[0074] Epoxy resin curing agent Q4 was prepared using essentially the same method as in Example 1, except that polyethylene glycol diglycidyl ether was not added.

[0075] The appearance of the epoxy resin curing agents prepared in each embodiment and comparative example was directly observed, and the transparency of the products was recorded.

[0076] The epoxy resin curing agents prepared in each example and comparative example were diluted according to the mass ratio of curing agent: water = 1:0.5, and stored under static conditions of 25°C and 45% humidity. The storage stability of each product was recorded, and the presence of insoluble substances such as water separation and precipitation was observed in the samples.

[0077] Then, the diluted epoxy resin curing agent was used to prepare different water-based coatings according to the formulations in Table 2 below, and paint film samples (film thickness 50μm) were applied. Pencil hardness tests were then performed using the method specified in GB6739-86, "Determination of Pencil Hardness of Coating Film". A 50℃ water immersion resistance test was also conducted using the method specified in Table 2.

[0078] Method C in GB / T9274-1988, "Determination of Resistance to Liquid Media for Paints and Varnishes", is used for neutral salt spray testing, and the test method is GB / T1771-1991, "Determination of Resistance to Neutral Salt Spray for Paints and Varnishes".

[0079] The specific test results for the above tests are shown in Table 3.

[0080] Table 2. Water-based Coating Formulations

[0081]

[0082]

[0083] Table 3. Performance Test Results

[0084]

[0085] As can be seen from the test results in Table 3, the paint film prepared by the water-based epoxy resin curing agent prepared in the embodiments of the present invention has good water resistance and corrosion resistance, as well as good water solubility and storage stability, which can meet the application requirements of epoxy resin flooring materials and has important application value.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A polyamide-based epoxy resin curing agent, characterized in that, It is prepared by reacting the following raw materials in parts by weight: a) 1-40 parts of hydrophobic amine; b) 5-30 parts of water-soluble amine; c) 10-40 parts of compounds containing carboxyl or ester groups; d) 5-40 parts of epoxy-based polyether; e) 0-40 parts of epoxy resin / compound; The hydrophobic amine is selected from diaminodicyclohexylmethane and its derivatives, dimethyldiaminodicyclohexylmethane and its derivatives, or a mixture of one or more of them; The water-soluble amine is selected from one or more of triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyetheramine, isophorone diamine, 1,3-cyclohexanedimethylamine, N-aminoethylpiperazine, N-aminopropylcyclohexylamine, and m-phenylenediamine; The carboxyl or ester-containing compound is selected from one or more of dimer acid, trimer acid, methyl dimer acid, ethyl dimer acid, and methyl trimer acid.

2. The polyamide-based epoxy resin curing agent according to claim 1, characterized in that, It is prepared by reacting the following raw materials in parts by weight: a) 5-30 parts of hydrophobic amine; b) 5-20 parts of water-soluble amine; c) 10-30 parts of compounds containing carboxyl or ester groups; d) 10-30 parts of epoxy-based polyether; e) 10-30 parts of epoxy resin / compound.

3. The polyamide-based epoxy resin curing agent according to claim 1, characterized in that, The epoxy polyether is selected from at least one of polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether with a weight average molecular weight of 100-10000.

4. The polyamide-based epoxy resin curing agent according to claim 1, characterized in that, The epoxy resin / compound is selected from one or more of epoxy resin E51, epoxy resin E44, epoxy resin E20, benzyl glycidyl ether, phenyl glycidyl ether, butyl glycidyl ether, C12-C14 alkyl glycidyl ether, 1,4-butanediol diglycidyl ether, and 1,2-ethylenediol diglycidyl ether.

5. The polyamide-based epoxy resin curing agent according to claim 4, characterized in that, The epoxy resin / compound is selected from at least one of epoxy resin E51, benzyl glycidyl ether, and C12-C14 glycidyl ether.

6. A method for preparing a polyamide epoxy resin curing agent as described in any one of claims 1-5, characterized in that, Includes the following steps: 1) Add components a), b), and c) to the reaction vessel, heat the mixture, and react to obtain the intermediate product; 2) After cooling the intermediate product obtained in step 1), add components d) and e) to continue the reaction. After the reaction, cool down to obtain the epoxy resin curing agent.

7. The method for preparing the polyamide-based epoxy resin curing agent according to claim 6, characterized in that, The reaction conditions in step 1) are: react at 70-100℃ with stirring for 1-2 hours, then raise the temperature to 100-270℃ and continue the reaction for 0.5-10 hours.

8. The method for preparing the polyamide-based epoxy resin curing agent according to claim 7, characterized in that, The reaction conditions in step 2) are: react at 70-100℃ with stirring for 1-4 hours.

9. The application of a polyamide epoxy resin curing agent as described in any one of claims 1-5 or a polyamide epoxy resin curing agent prepared by the method described in any one of claims 6-8 in water-based coatings.

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