Aromatic amine curing agent composition as well as preparation method and application thereof

Abstract

The invention provides an aromatic amine curing agent composition as well as a preparation method and application thereof, the aromatic amine curing agent composition comprises the following components in percentage by mass: 50-65wt% of a component A, 30-45wt% of a component B and # imgabs 1 #, the main structure of the curing agent has aromatic ring and alicyclic structures at the same time, the curing agent has basic properties of the aromatic ring and the alicyclic structure, and the curing agent has higher glass transition temperature than conventional alicyclic amine. Meanwhile, the melting point of the curing agent is effectively reduced, use of downstream customers is greatly facilitated, the curing reaction activity is improved, and the construction efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin curing agents, and particularly relates to an aromatic amine curing agent composition with low melting point and high adhesive density, and a preparation method and application thereof. Background Art

[0002] Epoxy resins have the characteristics of high viscosity, small shrinkage rate, good dielectric properties and excellent heat resistance, and are widely used in the fields of electronics, adhesives, coatings, construction and national defense. In the application of epoxy resins, a curing agent must be used to carry out a curing reaction with it, and only after forming a three-dimensional networked three-dimensional structure can excellent properties be exhibited. For most amine curing agents, the curing process is formed by the addition polymerization of the amino group of the curing agent and the epoxy group. With different curing agents, the molecular weight, morphology and crosslinking density in the crosslinked network will also be different, so that the mechanical properties, thermal stability and chemical stability of the entire epoxy cured product will also vary. Therefore, the research on various curing agents is an important part of the application research of epoxy resins.

[0003] Currently, epoxy resin amine curing agents are mainly divided into lower aliphatic amines, cycloaliphatic amines and aromatic amines, etc. Among them, lower aliphatic amines include ethylenediamine, diethylenetriamine and hexamethylenediamine, etc. However, such curing agents have high toxicity and strong volatility. Although the reaction activity is fast, they do not meet the environmental protection requirements. Cycloaliphatic amine curing agents include 1,3-BAC, HMDA and IPDA, etc. IPDA is restricted in its application due to strong moisture absorption and easy salt formation. HMDA is restricted in its application because of its slow surface drying time and inconvenient cleaning in time. 1,3-BAC is also restricted in its popularization and development due to its high price. Aromatic amine curing agents include MDA and p-phenylenediamine, etc. Such curing agents have a high melting point and are solids at room temperature, which is inconvenient for downstream construction. At the same time, the reaction activity of aromatic amines is low, and they cannot meet the fast curing requirements of related fields.

[0004] In view of the above problems, the industry generally adopts the method of amine compounding or amine modification to adjust its comprehensive performance. Such as the addition modification of amine curing agents with glycidyl ether, the addition modification with epoxy resin, the reaction modification with epichlorohydrin, the addition modification with ethylene oxide or propylene oxide, Michael addition modification reaction, self-condensation modification, ketimine reaction modification, condensation modification with thiourea, Mannich reaction modification and reaction modification with organic carboxylic acids, etc.

[0005] CN1460689A uses a modified alicyclic amine curing agent composed of 38 - 45% by weight of IPDA, 12 - 18% of epoxy resin, and 37 - 50% of benzyl alcohol. CN103224611A uses, by weight, 37 - 42 parts of 1,3 - cyclohexanedimethanamine, 12 - 16 parts of epoxy resin, and 42 - 51 parts of benzyl alcohol as raw materials to produce a modified alicyclic amine curing agent after reaction. Such a method of modification by pre - curing with epoxy resin is used to overcome the disadvantages of large heat release, easy volatilization, and easy moisture absorption and whitening during the curing of alicyclic amine curing agents. However, in the modified alicyclic amine curing system prepared by this method, the content of the solvent benzyl alcohol is about 50%, the active hydrogen equivalent of the effective amine components is relatively low, and the strength of the cured product is weak.

[0006] CN103524717A discloses a modified alicyclic amine curing agent, which is formed by the reaction of two raw materials, methylcyclohexanediamine and acrylonitrile, to overcome the disadvantages such as salt formation and whitening of traditional alicyclic amine curing agents. However, the glass transition temperature of this curing agent is relatively low, resulting in poor hardness of the finished product and unable to meet the high - strength use requirements.

[0007] US3231601A investigated the cyanoethylation reaction of aromatic primary amines and secondary amines, mainly using strong acids such as sulfuric acid, phosphoric acid, hydrochloric acid, and p - toluenesulfonic acid as catalysts. The modification process flow is relatively complex, the post - treatment of the acid requires a large amount of waste brine, and at the same time, it has relatively high requirements for the equipment material. Moreover, after the aromatic primary amine is modified with acrylonitrile, the melting point is still relatively high, which is not conducive to downstream construction.

[0008] CN106634755A discloses a preparation method of epoxy - modified HMDA. This curing agent can improve the curing speed of HMDA when used in the field of caulking, but the viscosity of this curing agent is relatively large and it is difficult to mix with thixotropic agents, which is very inconvenient for downstream construction. In addition, due to its linear molecular structure, it cannot obtain sufficient adhesive density, and the strength of the product also fails to meet the requirements.

[0009] In view of the above problems and the industry status, it is necessary to provide a new curing agent with both high activity and high glass transition temperature, and at the same time with a low melting point for convenient downstream construction and high adhesive density to improve the hardness of the product. Summary of the Invention

[0010] In view of the above problems existing in the prior art, one of the purposes of the present invention is to provide an aromatic amine - based curing agent composition, which has a high glass transition temperature, a low melting point, and high hardness.

[0011] Another purpose of the present invention is also to provide a preparation method of the above - mentioned aromatic amine - based curing agent composition. Using the semi - aromatic diamine compound H6MDA as the reaction raw material, cyanoethylation and hydrogenation reactions are carried out in sequence to generate a new curing agent, which has the dual characteristics of aromatic amines and alicyclic amines.

[0012] A third object of the present invention is also to provide an application of the aromatic amine curing agent composition in the field of epoxy resin curing.

[0013] To achieve the above object, the present invention adopts the following technical solutions:

[0014] In a first aspect, the present invention provides an aromatic amine curing agent composition, which, based on the total mass of the composition, comprises the following components in mass percentages:

[0015] 50 - 65 wt%, such as 50 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt%, 60 wt%, 62 wt%, 64 wt%, 65 wt%, preferably 55 - 60 wt% of component A,

[0016]

[0017] 30 - 45 wt%, such as 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 44 wt%, 45 wt%, preferably 35 - 40 wt% of component B,

[0018]

[0019] In the present invention, the aromatic amine curing agent composition is prepared by successively carrying out a cyanoethylation reaction and a hydrogenation reaction on H6MDA and acrylonitrile; preferably, the H6MDA contains 95 - 100 wt%, such as 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 100 wt% of 2,4'-H6MDA. The composition of the H6MDA product in the prior art is relatively complex, usually in the form of a composition, containing two components, 2,4'-H6MDA and 4,4'-H6MDA, and 2,4'-H6MDA also contains two isomers at the same time.

[0020] In the present invention, the aromatic amine curing agent composition may further contain 0 - 5 wt% of other components, and the other components may be impurities introduced by each raw material, or by-products generated during the preparation process, etc.; for example, when H6MDA is used as a raw material, the other components include the cyanoethylation and hydrogenation reaction products of 4,4'-H6MDA and unreacted fully hydrogenated a-ACN and b-ACN and other components.

[0021] Second aspect, the present invention provides a method for preparing the above aromatic amine curing agent composition. Those skilled in the art should understand that the following preparation method is only an exemplary illustration of the source mode of the aromatic amine curing agent composition product with the above characteristics of the present invention, but does not constitute any limitation. The aromatic amine curing agent composition of the present invention is not limited only to the preparation methods listed below. For example, by directly purchasing existing products or separately preparing each component and obtaining the curing agent composition of the above formula through conventional methods such as compounding and adding.

[0022] Hereinafter, the present invention exemplarily provides a method for preparing the aromatic amine curing agent composition. This preparation method is obtained by successively carrying out cyanoethylation reaction and hydrogenation reaction on H6MDA and acrylonitrile. By controlling the ratio of 2,4'-H6MDA isomer to 4,4'-H6MDA isomer in H6MDA, the aromatic amine curing agent composition is prepared. This can reduce the molecular symmetry, thereby greatly reducing the freezing point of the curing agent, and at the same time increasing the reticular adhesive density of the cured product. In addition, after being modified with acrylonitrile and hydrogen, the amino activity of the new curing agent is greatly increased, effectively improving the curing efficiency.

[0023] In a preferred embodiment, the present invention provides a method for preparing the aromatic amine curing agent composition as described above, and the specific steps are as follows:

[0024] 1) Cyanoethylation reaction: Mix H6MDA, acrylonitrile, and a solvent, and carry out a cyanoethylation reaction;

[0025] 2) Hydrogenation reaction: Add a Raney catalyst to the cyanoethylation reaction solution obtained in step 1), and carry out a hydrogenation reaction;

[0026] 3) Rectification and purification: The hydrogenation reaction solution obtained in step 2) is filtered and rectified under reduced pressure to obtain the aromatic amine curing agent composition.

[0027] In the present invention, the H6MDA in step 1) contains 95 - 100 wt%, such as 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 100 wt% of 2,4'-H6MDA;

[0028] Preferably, the H6MDA contains 95-100 wt%, such as 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 100 wt% of 2,4'-H6MDA and 0-5 wt%, such as 0 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% of 4,4'-H6MDA, based on the total mass of H6MDA; wherein, the 2,4'-H6MDA contains 40-80 wt%, such as 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt% of component (a) 2-((4-aminocyclohexyl)methyl)aniline and 20-60 wt%, such as 20 wt%, 20 wt%, 40 wt%, 50 wt%, 60 wt%, 100 wt% of component (b) 4-((2-aminocyclohexyl)methyl)aniline, preferably contains 50-70 wt% of component (a) and 30-50 wt% of component (b), based on the total mass of 2,4'-H6MDA.

[0029] In H6MDA, component A and component B in the aromatic amine curing agent composition are respectively obtained from component (a) and component (b), and the specific reaction formula is as follows:

[0030]

[0031] In the present invention, the molar ratio of the H6MDA to acrylonitrile in step 1) is 1:1-2, preferably 1:1.05-1.1, such as 1:1.05, 1:1.07, 1:1.09, 1:1.1.

[0032] In the present invention, the solvent in step 1) is selected from any one or at least two combinations of alcohols, ethers, and alkane organic compounds, preferably any one or at least two combinations of dioxane, tetrahydrofuran, methanol, ethanol, isopropanol, and methylcyclohexane, and more preferably ethanol.

[0033] In the present invention, the mass ratio of the solvent to H6MDA in step 1) is 0.5-2:1, such as 0.5:1, 0.8:1, 1:1, 1.3:1, 1.5:1, 1.8:1, 2:1, and preferably 1:1.

[0034] In the present invention, for the cyanoethylation reaction in step 1), the reaction temperature is 20-70 °C, such as 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, and preferably 30-50 °C; the reaction time is 1-10 h, such as 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, and preferably 2-4 h;

[0035] Preferably, the acrylonitrile is added dropwise, and the feeding time is 0.5-1 h, such as 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, and the feeding time is included in the reaction time.

[0036] In the present invention, the Raney catalyst described in step 2) is Raney cobalt and / or Raney nickel.

[0037] In the present invention, the dosage of the Raney catalyst described in step 2) is 1-10 wt%, such as 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 10 wt%, preferably 4-6 wt%, based on the mass of H6MDA in step 1).

[0038] In the present invention, for the hydrogenation reaction described in step 2), the reaction temperature is 80-150 °C, such as 80 °C, 100 °C, 120 °C, 140 °C, 150 °C, preferably 100-120 °C; the reaction pressure is 1-10 MPaG, such as 1 MPaG, 3 MPaG, 5 MPaG, 7 MPaG, 9 MPaG, 10 MPaG, preferably 3-5 MPaG; the reaction time is 1-10 h, such as 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, preferably 6-8 h.

[0039] In the present invention, for the vacuum distillation described in step 3), the temperature is 100-150 °C, such as 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, preferably 110-120 °C; the pressure is 1-20 KPaA, such as 1 KPaA, 5 KPaA, 10 KPaA, 15 KPaA, 20 KPaA, preferably 5-10 KPaA; the treatment time is 1-5 h, such as 1 h, 2 h, 3 h, 4 h, 5 h, preferably 2-3 h.

[0040] In the third aspect, the present invention provides the application of the aromatic amine curing agent composition.

[0041] The present invention provides that the aromatic amine curing agent composition is applicable to fields such as epoxy resin curing, especially applicable to fields such as adhesives, mold manufacturing, and electronic potting.

[0042] Compared with the prior art, the technical solution provided by the present invention has the following positive effects:

[0043] 1. The present invention provides an aromatic amine curing agent composition, whose main structure simultaneously has an aromatic ring and an alicyclic ring structure, combining the basic properties of both, and has a higher glass transition temperature than conventional alicyclic amines. At the same time, the melting point of the curing agent is effectively reduced, which greatly facilitates the use of downstream customers, effectively improves the curing reaction activity, and significantly increases the construction efficiency.

[0044] 2. The present invention also provides a method for preparing an aromatic amine curing agent composition, which uses H6MDA as the base amine for modification. According to the activity difference of the two amino groups in H6MDA, acrylonitrile is used to modify the amino group connected to the alicyclic ring, so as to enhance the amino group activity while introducing branched chains and destroying the symmetry of the original molecule, significantly reducing the melting point of the curing agent, changing the polymerization mode with epoxy resin from linear polymerization to network polymerization, further enhancing its adhesive density, and significantly improving the strength of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the NMR characterization spectrum of component A;

[0046] Figure 2 is the NMR characterization spectrum of component B. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention. The source information of the raw materials used in the following examples or comparative examples is as follows. Unless otherwise specified, all are commercially available industrial-grade conventional raw materials:

[0048] H6MDA raw material: contains 98.5 wt% of 2,4'-H6MDA and 1.5 wt% of 4,4'-H6MDA, based on the total weight of H6MDA. Among them, 2,4'-H6MDA contains (a) about 60 wt% and (b) about 40 wt%, based on the total weight of 2,4'-H6MDA; from Wanhua Special Amine Plant (using 2,4'-MDA as the raw material, carrying out batch autoclave high-pressure hydrogenation with a Ru catalyst at 140-160 °C and 8 MPa. When the total hydrogen consumption reaches 50%-70% of the theoretical benzene ring hydrogen consumption, the reaction is terminated; at this time, H6MDA raw material is separated at 2 KPa and 185 °C).

[0049] 4-((4-Aminocyclohexyl)methyl)aniline: contains 99.0 wt% of 4,4'-H6MDA and 1.0 wt% of 2,4'-H6MDA, based on the total weight of 4,4'-H6MDA; from Wanhua Special Amine Plant (using 4,4'-MDA as the raw material, carrying out batch autoclave high-pressure hydrogenation with a Ru catalyst at 120-140 °C and 8 MPa. When the total hydrogen consumption reaches 50%-70% of the theoretical benzene ring hydrogen consumption, the reaction is terminated; at this time, 4,4'-H6MDA raw material is separated at 2 KPa and 175 °C).

[0050] MDA raw material: from Wanhua WANAMINE MDA-100, contains 99.5 wt% of 4,4'-MDA and 0.5 wt% of 2,4'-MDA, based on the total weight of MDA.

[0051] Raw materials for HMDA: from Wanhua WANAMINE 2110, in which the purity of 4,4'-HMDA is ≥99.5 wt%.

[0052] Acrylonitrile: from Beijing Innochem (Shanghai Test), with a purity of ≥99 wt%;

[0053] Ethanol: from Aladdin Reagent Co., with a purity of ≥99 wt%;

[0054] Raney cobalt: Grace Co.;

[0055] Raney nickel: Grace Co.;

[0056] E51 epoxy resin: purchased from Hunan Baling Petrochemical, with a purity greater than 99.0%.

[0057] The analytical and testing methods used in the following examples or comparative examples are as follows:

[0058] Gas chromatography analysis method: Using Agilent 7890 series, DB-5 capillary chromatographic column, the temperature of the FID detector is 300 °C, the initial column temperature is 160 °C, rising to 300 °C at 10 °C / min and staying for 20 min.

[0059] Freezing point test method: Refer to GB / T 510-83.

[0060] Glass transition temperature (Tg) test method: Mix the curing agent and epoxy resin E51 in a mass ratio of 30:100 at 40 °C for about 3 h, then cure at 130 °C for 5 h, and then test the cured product by DSC, from room temperature to 300 °C, with a heating rate of 10 °C / min.

[0061] Shore hardness test method: Refer to ASTM D2240 for testing, at 25 °C * 24 h.

[0062] Example 1

[0063] Aromatic amine curing agent composition (Curing agent 1), the steps are as follows:

[0064] 1) Cyanoethylation reaction: Dissolve 204 g (1 mol) of H6MDA raw material in 400 g of ethanol. After it is completely dissolved, add it to a 1 L three-necked flask with mechanical stirring. Use a constant pressure dropping funnel to drop 56 g (1.06 mol) of acrylonitrile into the ethanol solution of H6MDA within 1 h, control the reaction temperature at 30 °C, start timing from the start of acrylonitrile dropping, and stop the reaction after 4 h.

[0065] 2) Hydrogenation reaction: Add 8.2 g of Raney cobalt catalyst into a 1.5 L stainless steel high-pressure reactor, and at the same time add all the crude product liquid of the cyanoethylation in the above step 1). Use 1 MPaA N 2 and H 2 to conduct gas displacement on the materials in the reactor. Subsequently, under the conditions of 120 °C and 5 MPaG hydrogen, after about 8 h of hydrogenation reaction, cool down and relieve pressure. After stopping the reaction, filter and separate the reaction liquid and the catalyst for standby.

[0066] 3) Rectification and purification: Rectify the crude product liquid of the hydrogenation reaction in the above step 2) under reduced pressure at 120 °C and 10 KPaA to remove light components such as ethanol and propylamine for about 3 h, and then obtain the aromatic amine curing agent composition. Analyzed by gas chromatography, the content of component A is 59.5 wt%, the content of component B is 38.3 wt%, and the content of the remaining components is 2.2 wt%.

[0067] The NMR characterizations of component A and component B are respectively as Figure 1 and Figure 2 shown.

[0068] Example 2

[0069] Aromatic amine curing agent composition (curing agent two), the steps are as follows:

[0070] 1) Cyanoethylation reaction: Dissolve 204 g (1 mol) of H6MDA raw material in 200 g of tetrahydrofuran. After it is completely dissolved, add it to a 1 L three-necked flask with mechanical stirring. Use a constant pressure dropping funnel to drop 58.5 g (1.1 mol) of acrylonitrile into the tetrahydrofuran solution of H6MDA within 0.5 h, control the reaction temperature at 50 °C, start timing from the start of acrylonitrile dropping, and stop the reaction after 2 h.

[0071] 2) Hydrogenation reaction: Add 12.2 g of Raney cobalt catalyst into a 1.5 L stainless steel high-pressure reactor, and at the same time add all the crude product liquid of the cyanoethylation in the above step 1). Use 1 MPaAN 2 and H 2 to conduct gas displacement on the materials in the reactor. Subsequently, under the conditions of 100 °C and 3 MPaG hydrogen, after about 6 h of hydrogenation reaction, cool down and relieve pressure. After stopping the reaction, filter and separate the reaction liquid and the catalyst for standby.

[0072] 3) Rectification and purification: Rectify the crude product liquid of the hydrogenation reaction in the above step 2) under reduced pressure at 110 °C and 5 KPaA to remove light components such as tetrahydrofuran and propylamine for about 2 h, and then obtain the aromatic amine curing agent composition. Analyzed by gas chromatography, the content of component A is 58.0 wt%, the content of component B is 38.0 wt%, and the content of the remaining components is 4.0 wt%.

[0073] Example 3

[0074] Aromatic amine curing agent composition (curing agent three), the steps are:

[0075] 1) Nitrile ethylation reaction: 204g (1 mol) H6MDA raw material was dissolved in 100g methanol, and after it was completely dissolved, it was added to a 1L three-necked flask with mechanical stirring. 106g (2 mol) acrylonitrile was added dropwise to the methanol solution of H6MDA within 1 hour using a constant pressure dropping funnel, and the reaction temperature was controlled at 65°C. The timing was started from the addition of acrylonitrile, and the reaction was stopped after 10 hours.

[0076] 2) Hydrogenation reaction: 20.4 g of Raney nickel catalyst was added to a 1.5 L stainless steel autoclave, and all the crude ethyl nitrile product solution of step 1) was added at the same time. 1 MPa AN 2 and H 2 The material in the kettle was replaced with gas. Then, the hydrogenation reaction was carried out at 80°C and 9MPaG hydrogen for about 10 hours, and then the temperature was lowered and the pressure was released. After the reaction was stopped, the reaction liquid and the catalyst were filtered and separated for later use.

[0077] 3) Purification by distillation: The crude product liquid of the hydrogenation reaction in step 2) is subjected to vacuum distillation at 100° C. and 1 KPaA to remove light components such as methanol and propylamine for about 1 hour to obtain an aromatic amine curing agent composition. According to gas chromatography analysis, the content of component A is 59.0wt%, the content of component B is 39.0wt%, and the content of the remaining components is 2.0wt%.

[0078] Comparative Example 1

[0079] The curing agent (comparative curing agent 1) was prepared by referring to the method of Example 1, except that the H6MDA raw material was replaced by 4-((4-aminocyclohexyl)methyl)aniline, and the other operations and conditions remained unchanged. The product was analyzed by gas chromatography, wherein the content of component A was 0.6wt%, the content of component B was 0.4wt%, and the content of the remaining components was 99.0wt%.

[0080] Comparative Example 2

[0081] The curing agent (comparative curing agent 2) was prepared by referring to the method of Example 2, except that the H6MDA raw material was replaced by the MDA raw material, and the other operations and conditions remained unchanged. The product was analyzed by gas chromatography, wherein the content of component A was 0wt%, the content of component B was 0wt%, and the content of the remaining components was 100wt%.

[0082] Comparative Example 3

[0083] The curing agent (Comparative Curing Agent III) was prepared by referring to the method of Example 3, with the only difference being that the H6MDA raw material was replaced with the HMDA raw material, and other operations and conditions remained unchanged. The product was analyzed by gas chromatography, in which the content of Component A was 0 wt%, the content of Component B was 0 wt%, and the content of the remaining components was 100 wt%.

[0084] Test Example 1

[0085] The freezing point of the amine raw materials and the modified curing agents used in the above Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 510-83; the glass transition temperature of the amine raw materials and the modified curing agents used in the above Examples 1-3 and Comparative Examples 1-3 was tested according to the above glass transition temperature test method;

[0086] The above test results are compared as shown in Table 1 below:

[0087] Table 1

[0088]

[0089]

[0090] As can be seen from Table 1 above, except that the freezing point of Comparative Curing Agent II based on MDA did not decrease significantly, the freezing points of the other amines decreased significantly after being modified by this process. This is mainly because both amino groups in MDA are connected to the benzene ring, resulting in weak activity and inability to carry out addition reaction with acrylonitrile, so the modification effect of the present invention cannot be achieved. The other amines in Table 1 above all contain one or two alicyclic amines, which are easy to undergo cyanoethylation reaction with acrylonitrile and finally generate the corresponding modified curing agent after hydrogenation, confirming that the modification method of the present invention is beneficial to reducing its melting point.

[0091] In addition, as can be seen from Table 1 above, except that the Tg of Comparative Curing Agent II based on MDA did not increase significantly, the Tg of the other amines increased to varying degrees after being modified by this process, confirming that the modification method of the present invention is also beneficial to increasing its Tg.

[0092] Test Example 2

[0093] The hardness of the amine raw materials and the modified curing agents used in the above Examples 1-3 and Comparative Examples 1-3 was tested and compared according to ASTM D2240, and the results are shown in Table 2 below:

[0094] Table 2

[0095]

[0096]

[0097] As can be seen from Table 2 above, since MDA and Comparative Curing Agent 2 synthesized from MDA as raw materials have a fully aromatic structure, the hardness of their products is the highest. Moreover, the hardness of the products of Curing Agent 1, Curing Agent 2, and Curing Agent 3 in Table 2 above all reaches over 120, far exceeding that of Comparative Curing Agent 1 with a semi-aromatic and semi-alicyclic structure, and even approaching the hardness level of MDA products, which proves that the modification method of the present invention is beneficial to improving the hardness of products.

Claims

1. An aromatic amine curing agent composition, characterized in that, based on the total mass of the composition, it contains the following components in mass percentage: 50 - 65 wt%, preferably 55 - 60 wt% of component A, 30 - 45 wt%, preferably 35 - 40 wt% of component B, 2. The aromatic amine curing agent composition according to claim 1, characterized in that, it is prepared by successively carrying out a cyanoethylation reaction and a hydrogenation reaction on H6MDA and acrylonitrile; preferably, the H6MDA contains 95 - 100 wt% of 2,4'-H6MDA; and / or the aromatic amine curing agent composition further contains 0 - 5 wt% of other components.

3. A preparation method of the aromatic amine curing agent composition according to claim 1 or 2, characterized in that, the specific steps are as follows: 1) Cyanoethylation reaction: Mix H6MDA, acrylonitrile, and a solvent, and carry out a cyanoethylation reaction; 2) Hydrogenation reaction: Add a Raney catalyst to the cyanoethylation reaction solution obtained in step 1), and carry out a hydrogenation reaction; 3) Rectification and purification: The hydrogenation reaction solution obtained in step 2) is filtered and subjected to vacuum rectification to obtain the aromatic amine curing agent composition.

4. The preparation method according to claim 3, characterized in that, the H6MDA in step 1) contains 95 - 100 wt% of 2,4'-H6MDA; preferably, the H6MDA contains 95 - 100 wt% of 2,4'-H6MDA and 0 - 5 wt% of 4,4'-H6MDA, based on the total mass of H6MDA; wherein, 2,4'-H6MDA contains 40 - 80 wt% of component (a) 2-((4-aminocyclohexyl)methyl)aniline and 20 - 60 wt% of component (b) 4-((2-aminocyclohexyl)methyl)aniline, preferably contains 50 - 70 wt% of component (a) and 30 - 50 wt% of component (b), based on the total mass of 2,4'-H6MDA.

5. The preparation method according to claim 3, characterized in that, the molar ratio of H6MDA to acrylonitrile in step 1) is 1:1 - 2, preferably 1:1.05 - 1.1; and / or the solvent in step 1) is selected from any one or at least two combinations of alcohols, ethers, and alkane organic compounds, preferably any one or at least two combinations of dioxane, tetrahydrofuran, methanol, ethanol, isopropanol, and methylcyclohexane, more preferably ethanol; and / or the mass ratio of the solvent to H6MDA in step 1) is 0.5 - 2:1, preferably 1:

1.

6. The preparation method according to claim 3, characterized in that, for the cyanoethylation reaction in step 1), the reaction temperature is 20 - 70 °C, preferably 30 - 50 °C; the reaction time is 1 - 10 h, preferably 2 - 4 h; preferably, the acrylonitrile is added dropwise, and the feeding time is 0.5 - 1 h, and the feeding time is included in the reaction time.

7. The preparation method according to claim 3, characterized in that, the Raney catalyst in step 2) is Raney cobalt and / or Raney nickel; and / or The dosage of the Raney catalyst described in step 2) is 1-10 wt%, preferably 4-6 wt%, based on the mass of H6MDA in step 1).

8. The preparation method according to claim 3, characterized in that in the hydrogenation reaction described in step 2), the reaction temperature is 80-150 °C, preferably 100-120 °C; the reaction pressure is 1-10 MPaG, preferably 3-5 MPaG; the reaction time is 1-10 h, preferably 6-8 h.

9. The preparation method according to claim 3, characterized in that in the vacuum distillation described in step 3), the temperature is 100-150 °C, preferably 110-120 °C; the pressure is 1-20 KPaA, preferably 5-10 KPaA; the treatment time is 1-5 h, preferably 2-3 h.

10. The application of the aromatic amine curing agent composition according to claim 1 or 2, or the aromatic amine curing agent composition prepared by the method according to any one of claims 3-9, in the field of epoxy resin curing, and is particularly suitable for the fields of adhesives, mold manufacturing, and electronic potting.

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