A low-sensitivity epoxy resin curing agent and preparation method thereof

Abstract

The invention provides a low-sensitivity epoxy resin curing agent and a preparation method thereof, and relates to the technical field of curing agent preparation. The preparation method of the low-sensitivity epoxy resin curing agent comprises the following steps: respectively taking aliphatic amine and halogenated phenylthiourea to mix, heating to 90-120°C for 3-5 hours, and then distilling under negative pressure at -0.08MPa to -0.1MPa, cooling the reaction system, and obtaining the low-sensitivity epoxy resin curing agent, wherein the epoxy resin curing agent has low sensitization.

Description

Technical Field

[0001] The invention relates to the technical field of curing agent preparation, and in particular to a low-sensitivity epoxy resin curing agent and a preparation method thereof. Background Art

[0002] Epoxy resin is a high molecular polymer, which refers to a class of polymers containing more than two epoxy groups in the molecule. It can be opened by a variety of compounds containing active hydrogen, and cured and cross-linked to form a network structure. Therefore, one of the important factors affecting the curing performance of epoxy resin is the curing agent that matches it. The choice of curing agent plays a decisive role in the use effect of epoxy resin. Polyamide curing agents have high viscosity and poor curing at low temperatures; aliphatic polyamine curing agents react too quickly, release a lot of heat, and have a short service life, but are volatile and highly toxic.

[0003] Composite materials for wind turbine blades are often constructed by hand-laying using fiberglass cloth, epoxy resin, and aliphatic polyamine curing agents. During on-site construction, even when wearing PPE and other safety protection measures, workers still suffer from allergies. This is because aliphatic polyamine curing agents are volatile, causing irritation to workers when they inhale them or skin irritation. Therefore, the development of a low-allergenic epoxy resin curing agent has become a technical problem that urgently needs to be solved in this field. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a low-sensitivity epoxy resin curing agent and a preparation method thereof.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a low-sensitivity epoxy resin curing agent, comprising the following steps: separately taking aliphatic amine and halogenated phenylthiourea, mixing them, heating them to 90-120°C and keeping them warm for 3-5 hours, and then distilling them under negative pressure at -0.08MPa to -0.1MPa, cooling the reaction system, and obtaining a low-sensitivity epoxy resin curing agent.

[0009] Preferably, the halogenated phenylthiourea comprises chlorophenylthiourea.

[0010] Preferably, the chlorophenylthiourea is selected from any one of 2,6-dichlorophenylthiourea, 4-chlorophenylthiourea and 3,4-dichlorophenylthiourea.

[0011] Preferably, the fatty amine is selected from any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and ethylenediamine.

[0012] Preferably, the molar ratio of the halogenated phenylthiourea to the fatty amine is 1:1.5-2.5.

[0013] Preferably, the molar ratio of the halogenated phenylthiourea to the fatty amine is 1:2.0.

[0014] In a second aspect, the present invention provides a low-sensitivity epoxy resin curing agent obtained by the preparation method described in the first aspect, comprising a fatty amine and chlorophenylthiourea.

[0015] Preferably, the epoxy resin and the low-sensitivity epoxy resin curing agent are mixed in a mass ratio of 100:30-50 and then cured.

[0016] Preferably, the curing conditions are curing at 20-25° C. for 40-48 hours and then curing at 70-80° C. for 10-12 hours.

[0017] Preferably, the curing conditions are curing at 23° C. for 45 hours and then curing at 75° C. for 11 hours.

[0018] (III) Beneficial effects

[0019] The present invention provides a low-sensitivity epoxy resin curing agent and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects:

[0020] The invention discloses a method for preparing a low-sensitivity epoxy resin curing agent, comprising the following steps: respectively taking aliphatic amine and halogenated phenylthiourea to mix, heating to 90-120°C for 3-5 hours, then distilling under negative pressure at -0.08MPa to -0.1MPa, cooling the reaction system, and obtaining a low-sensitivity epoxy resin curing agent; introducing chlorine atoms by reacting an existing amine curing agent with chlorophenylthiourea at a molar ratio of 1.5-2.5:1, thereby increasing the polarity of the curing agent molecule; therefore, the positive and negative charges between the prepared epoxy resin curing agent molecules are unevenly distributed, forming a dipole-dipole force, thereby increasing the force between the prepared epoxy resin curing agent molecules, increasing the boiling point of the epoxy resin curing agent, making the epoxy resin curing agent less volatile, and reducing the sensitization of the epoxy resin curing agent. Moreover, the cured product obtained by curing the epoxy resin with the epoxy resin curing agent prepared by the reaction of the existing amine curing agent with the chlorophenylthiourea has high impact resistance. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods. Example 1

[0023] This embodiment provides a method for preparing a low-sensitivity epoxy resin curing agent, comprising the following steps:

[0024] Weigh diethylenetriamine and add it into a four-necked flask. Then weigh 2,6-dichlorophenylthiourea and add it into the flask. The molar ratio of 2,6-dichlorophenylthiourea to diethylenetriamine is 1:1.5. Heat to 90°C and keep warm for 3 hours. Then, distill under negative pressure at -0.08MPa. Use tap water to cool the reaction system to obtain an epoxy resin curing agent.

[0025] The sensitization of the synthesized epoxy resin curing agent was tested according to GB / T 21604-2008 Acute Skin Irritation / Corrosion of Chemicals. The test results are shown in Table 1.

[0026] The curing performance of the synthesized epoxy resin curing agent is tested, comprising the following steps: epoxy resin E44 and the above epoxy resin curing agent are mixed and dispersed evenly in a mass ratio of 100:50, and then cured at 25°C / 48h+80°C / 12h to obtain a cured product. The impact resistance of the cured product is tested using a falling ball impact tester, in which a 100g ball is dropped from different heights, and the lowest height corresponding to the time when the cured product is broken is recorded. The test results are shown in Table 1. Example 2

[0027] This embodiment provides a method for preparing a low-sensitivity epoxy resin curing agent, comprising the following steps:

[0028] Weigh triethylenetetramine and add it into a four-necked flask, then weigh 4-chlorophenylthiourea and add it into the flask, the molar ratio of 4-chlorophenylthiourea to triethylenetetramine is 1:2.0, heat to 100°C and keep warm for 4 hours, then distill under negative pressure at -0.09MPa, cool the reaction system with tap water, and obtain an epoxy resin curing agent.

[0029] The sensitization of the synthesized epoxy resin curing agent was tested according to GB / T 21604-2008 Acute Skin Irritation / Corrosion of Chemicals. The test results are shown in Table 1.

[0030] The curing performance of the synthesized epoxy resin curing agent is tested, comprising the following steps: epoxy resin E44 and the above epoxy resin curing agent are mixed and dispersed evenly in a mass ratio of 100:50, and then cured and molded into a cured product according to a curing process of 23°C / 45h+75°C / 11h. The impact resistance thereof is tested by a falling ball impact tester, in which a 100 g ball is dropped from different heights, and the lowest height corresponding to the time when the cured product is broken is recorded. The test results are shown in Table 1. Example 3

[0031] This embodiment provides a method for preparing a low-sensitivity epoxy resin curing agent, comprising the following steps:

[0032] Weigh tetraethylenepentamine and add it into a four-necked flask, then weigh 3,4-dichlorophenylthiourea and add it into the flask, the molar ratio of 3,4-dichlorophenylthiourea to tetraethylenepentamine is 1:2.5, heat to 120°C and keep warm for 5 hours, then distill under negative pressure at -0.1MPa, cool the reaction system with tap water to obtain an epoxy resin curing agent.

[0033] The sensitization of the synthesized epoxy resin curing agent was tested according to GB / T 21604-2008 Acute Skin Irritation / Corrosion of Chemicals. The test results are shown in Table 1.

[0034] The curing performance of the synthesized epoxy resin curing agent is tested, comprising the following steps: epoxy resin E44 and the above epoxy resin curing agent are mixed and dispersed evenly in a mass ratio of 100:50, and then cured and molded into a cured product according to a curing process of 25°C / 48h+80°C / 12h. The impact resistance thereof is tested by a falling ball impact tester, in which a 100g ball is dropped from different heights, and the lowest height corresponding to the time when the cured product is broken is recorded. The test results are shown in Table 1.

[0035] Comparative Example 1

[0036] The difference between this comparative example and Example 1 is that phenylthiourea is used instead of 2,6-dichlorophenylthiourea to prepare the epoxy resin curing agent, and the other steps are the same as Example 1.

[0037] Comparative Example 2

[0038] The difference between this comparative example and Example 1 is that only diethylenetriamine is used as the epoxy resin curing agent, and the other conditions are the same as Example 1.

[0039] Comparative Example 3

[0040] The difference between this comparative example and Example 1 is that the molar ratio of the 2,6-dichlorophenylthiourea to diethylenetriamine is 1:1, and the other conditions are the same as those of Example 1.

[0041] Comparative Example 4

[0042] The difference between this comparative example and Example 1 is that the molar ratio of the 2,6-dichlorophenylthiourea to diethylenetriamine is 1:3, and the other conditions are the same as Example 1.

[0043] As can be seen from Table 1, compared with Comparative Examples 1-4, the epoxy resin curing agent prepared in Example 1-3 has lower sensitization. This is because the epoxy resin curing agent prepared in Example 1-3 introduces chlorine atoms by reacting aliphatic amine curing agent and chlorophenylthiourea under the condition that the molar ratio of chlorophenylthiourea to aliphatic amine curing agent is 1:1.5-2.5, which increases the polarity of the curing agent molecule. Therefore, the positive and negative charges between the prepared epoxy resin curing agent molecules are unevenly distributed, forming a dipole-dipole force, thereby increasing the force between the prepared epoxy resin curing agent molecules, increasing the boiling point of the epoxy resin curing agent, making the epoxy resin curing agent less volatile, and thus reducing the sensitization of the epoxy resin curing agent. In addition, the cured product obtained by curing epoxy resin with the epoxy resin curing agent prepared by the reaction of aliphatic amine curing agent and chlorophenylthiourea has high impact resistance.

[0044] Table 1 Performance test results of epoxy resin curing agents of Examples 1-3 and Comparative Examples 1-4

[0045]

[0046] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0048] The present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a low-sensitivity epoxy resin curing agent, characterized in that: The method comprises the following steps: respectively mixing aliphatic amine and halogenated phenylthiourea, heating to 90-120° C. and keeping the temperature for 3-5 hours, and then distilling under negative pressure at -0.08 MPa to -0.1 MPa to cool the reaction system to obtain a low-sensitivity epoxy resin curing agent; The fatty amine is selected from any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and ethylenediamine.

2. The preparation method according to claim 1, characterized in that The halogenated phenylthiourea includes chlorophenylthiourea.

3. The preparation method according to claim 2, characterized in that: The chlorophenylthiourea is selected from any one of 2,6-dichlorophenylthiourea, 4-chlorophenylthiourea and 3,4-dichlorophenylthiourea.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the halogenated phenylthiourea to the fatty amine is 1:1.5-2.

5.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the halogenated phenylthiourea to the fatty amine is 1:2.

0.

6. A low-sensitivity epoxy resin curing agent obtained by the preparation method according to any one of claims 1 to 5, characterized in that: Including fatty amines and chlorophenylthiourea.

7. The low-allergenic epoxy resin curing agent according to claim 6, characterized in that: The epoxy resin and the low-sensitivity epoxy resin curing agent are mixed in a mass ratio of 100:30-50 and then cured.

8. The low-allergenic epoxy resin curing agent according to claim 7, characterized in that: The curing conditions are curing at 20-25° C. for 40-48 hours and then curing at 70-80° C. for 10-12 hours.

9. The low-allergenic epoxy resin curing agent according to claim 8, characterized in that: The curing conditions are curing at 23° C. for 45 hours and then curing at 75° C. for 11 hours.

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