Two-component epoxy resin adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of polymer adhesives, and particularly relates to a two-component epoxy resin adhesive and a preparation method thereof. The bi-component epoxy resin adhesive is prepared by mixing a component A and a component B according to a weight ratio of 100: (20-50). The component A comprises the following components in parts by weight: 60-90 parts of epoxy resin; 5-30 parts of a polymer toughening agent with a core-shell structure; and 1-10 parts of a reactive diluent. The component B comprises 70-95 parts of a modified polyether amine curing agent; 0.5 to 5 parts of an accelerant; and 1-5 parts of a coupling agent. Through the synergistic effect of the core-shell structure polymer toughening agent and the modified polyether amine curing agent with a specific structure, the impact resistance, stripping resistance and fatigue resistance of the epoxy resin are remarkably improved while the high strength of the epoxy resin is maintained. The adhesive is suitable for the fields of aerospace, new energy automobiles, wind power blades and the like with extremely high requirements on mechanical properties of structural adhesives.

Description

Technical Field

[0001] This application belongs to the field of polymer adhesive technology, specifically relating to a two-component epoxy resin adhesive with high toughness and high strength and its preparation method. Background Technology

[0002] Epoxy resin adhesives are widely used in various sectors of the national economy due to their excellent bonding strength, chemical stability, electrical insulation, and low shrinkage. However, traditional epoxy resins have high crosslinking density after curing, making molecular chain segment movement difficult. This results in drawbacks such as high internal stress, brittleness, and poor impact and peel resistance, which greatly limits their application in structural components subjected to dynamic or impact loads, such as automobile bodies, aircraft skins, and wind turbine blades.

[0003] To improve the toughness of epoxy resins, existing technologies typically employ the following methods: 1. Toughening with liquid rubber: such as toughening with carboxyl-terminated nitrile butadiene rubber (CTBN). While this method can improve toughness, it often significantly reduces the strength, modulus, and heat resistance of the adhesive. Furthermore, the rubber phase has poor compatibility with the epoxy matrix, leading to easy phase separation and affecting performance stability. 2. Toughening with thermoplastic resins: such as polysulfone and polyethersulfone. These materials can improve toughness without sacrificing heat resistance, but their high processing viscosity makes blending with epoxy resins difficult, and the toughening effect is limited. 3. Toughening with inorganic nanoparticles: such as nano-silica and nano-montmorillonite. This method can simultaneously improve strength, modulus, and toughness, but nanoparticles are prone to agglomeration, making dispersion difficult, the process complex, and reproducibility poor.

[0004] Core-shell polymers are a novel type of toughening agent, with a soft elastomer core and a glassy polymer with good compatibility with epoxy resins as the outer shell. This structure allows them to effectively induce crazes and shear bands to dissipate energy, while also maintaining stable dispersion in epoxy resins and resisting phase separation, making them ideal toughening agents for epoxy resins. However, achieving the optimal balance between toughness, strength, and processability by combining core-shell toughening agents with suitable curing systems remains a technical challenge that needs to be addressed in this field. Summary of the Invention

[0005] The purpose of this application is to provide a two-component epoxy adhesive with high toughness, high strength and excellent comprehensive performance. It achieves excellent mechanical properties through a unique component design, especially the synergistic effect of core-shell toughening agent and specific modified polyetheramine curing agent.

[0006] To address the aforementioned technical problems, this application provides the following technical solution.

[0007] In a first aspect, this application provides a two-component epoxy resin adhesive, which is composed of component A and component B mixed in a weight ratio of 100:(20-50); Wherein, by weight, component A comprises: Epoxy resin: 60-90 parts; Core-shell structured polymer toughening agent: 5-30 parts; Reactive diluent: 1-10 parts; Wherein, by weight, component B comprises: Modified polyetheramine curing agent: 70-95 parts; Accelerator: 0.5-5 parts; Coupling agent: 1-5 parts.

[0008] In one embodiment of the first aspect, the epoxy resin is one or a mixture of two of bisphenol A type epoxy resin and bisphenol F type epoxy resin.

[0009] In one embodiment of the first aspect, the core of the core-shell structured polymer toughening agent is a cross-linked elastomer of polybutadiene and polybutyl acrylate, and the shell is a polymethyl methacrylate or epoxy resin compatible polymer.

[0010] In one embodiment of the first aspect, the active diluent is one or more of butyl glycidyl ether, phenyl glycidyl ether, and 1,4-butanediol diglycidyl ether.

[0011] In one embodiment of the first aspect, the modified polyetheramine curing agent is a product of polyetheramine prepolymerized with epoxy resin or modified with Mannich base, and its amine value is 200-400 mg KOH / g.

[0012] In one embodiment of the first aspect, the promoter is one or both of 2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine.

[0013] In one embodiment of the first aspect, the coupling agent is one or both of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0014] In one embodiment of the first aspect, the epoxy resin is bisphenol A type epoxy resin E-51; the core-shell structure polymer toughening agent is a toughening agent sold by Kaneka Corporation of Japan with the model number MX-156; the reactive diluent is butyl glycidyl ether; the modified polyetheramine curing agent is Mannich modified polyetheramine, which is sold by Huntsman Corporation of the United States with the model number JEFFAMINE® XTJ-586; the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol; and the coupling agent is γ-aminopropyltriethoxysilane.

[0015] In a second aspect, this application provides a method for preparing a two-component epoxy resin adhesive as described in the first aspect, comprising the following steps: S1: Preparation of Component A At 40-60℃, stir the epoxy resin, core-shell structured polymer toughening agent and reactive diluent for 1-3 hours until the mixture is uniform and transparent. After vacuum degassing, discharge and package. S2: Preparation of component B: Stir the modified polyetheramine curing agent, accelerator and coupling agent at room temperature for 0.5-1 hour until they are evenly mixed. After vacuum degassing, discharge and package.

[0016] In one embodiment of the second aspect, in step S1, the order of adding materials during the mixing process is as follows: epoxy resin, core-shell structured polymer toughening agent, and reactive diluent are added sequentially. In step S2, the order of adding materials during the mixing process is as follows: modified polyetheramine curing agent, accelerator, and coupling agent are added sequentially.

[0017] Compared with the prior art, the positive effects of this application are that the two-component epoxy resin adhesive of this application has the following advantages: 1. High toughness: Core-shell toughening agents can effectively induce, terminate, and branch crazes, consuming a large amount of impact energy, thus significantly improving the fracture toughness and impact resistance of the adhesive layer; 2. High strength and high modulus: Due to the good compatibility between the shell of the core-shell particles and the epoxy matrix, the problem of severely sacrificing strength and modulus, as seen in liquid rubber, is avoided. Modified polyetheramine curing agents can form a strong and tough cross-linked network; 3. Synergistic effect: The modified polyetheramine with flexible segments, together with the rigid epoxy network and dispersed core-shell elastic particles, constitute a multiphase composite structure of "rigid-flexible-elastic", achieving the optimal balance of mechanical properties; 4. Good processability: Components A and B have moderate viscosity at room temperature, making them easy to mix and apply. They have a moderate pot life and can be cured quickly at medium temperatures (e.g., 80-100℃) or slowly at room temperature. Detailed Implementation

[0018] Unless otherwise stated, implied from the context, or as is customary in the art, all parts and percentages in this application are based on weight, and all testing and characterization methods used are concurrent with the filing date of this application. Where applicable, any patent, patent application, or disclosure relating to this application is incorporated herein by reference in its entirety, and its equivalent patent families are also incorporated herein by reference, particularly the definitions disclosed in these documents concerning synthetic techniques, product and processing design, polymers, comonomers, initiators, or catalysts in the art. If any definition of a specific term disclosed in the prior art is inconsistent with any definition provided in this application, the definition provided in this application shall prevail.

[0019] The numerical ranges in this application are approximate values ​​and therefore may include values ​​outside the range unless otherwise stated. A numerical range includes all values ​​from the lower limit to the upper limit, increasing by one unit, provided there is an interval of at least two units between any lower and any higher value. For example, if the stated composition, physical, or other property (such as molecular weight, melt index, etc.) is 100 to 1000, it means that all individual values, such as 100, 101, 102, etc., are explicitly listed, as well as all subranges, such as 100 to 166, 155 to 170, 198 to 200, etc. For ranges containing values ​​less than 1 or fractions greater than 1 (e.g., 1.1, 1.5, etc.), one unit is appropriately considered as 0.0001, 0.001, 0.01, or 0.1. For ranges containing single digits less than 10 (e.g., 1 to 5), one unit is generally considered as 0.1. These are merely specific examples of what is intended to be expressed, and all possible combinations of values ​​between the listed minimum and maximum values ​​are considered to be clearly stated in this application. It should also be noted that the terms "first," "second," etc., used herein are not intended to specify a particular order, but are merely used to distinguish substances with different structures.

[0020] When referring to chemical compounds, unless explicitly stated otherwise, the singular includes all isomers and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively). Additionally, unless explicitly stated otherwise, nouns described with "an," "a," or "the" also include their plural forms.

[0021] The terms “comprising,” “including,” “having,” and their derivatives do not exclude the presence of any other components, steps, or processes, regardless of whether such other components, steps, or processes are disclosed in this application. To eliminate any doubt, unless expressly stated otherwise, all compositions using the terms “comprising,” “including,” or “having” in this application may contain any additional additives, excipients, or compounds. Conversely, except for those necessary for operational performance, the term “substantially constitutes…” excludes any other components, steps, or processes described below with respect to that term. The term “consisting of…” does not include any components, steps, or processes not specifically described or listed. Unless expressly stated otherwise, the term “or” refers to the individual members listed or any combination thereof.

[0022] In one specific embodiment, this application discloses a high-toughness, high-strength two-component epoxy resin adhesive and its preparation method. The adhesive consists of component A and component B, wherein component A comprises epoxy resin, a core-shell structured polymer toughening agent, and an active diluent; component B comprises a modified polyetheramine curing agent, an accelerator, and a coupling agent. The core of this application lies in the synergistic effect of the core-shell structured polymer toughening agent and the specifically structured modified polyetheramine curing agent, which significantly improves the impact resistance, peel resistance, and fatigue resistance of the epoxy resin while maintaining its high strength. This adhesive is suitable for fields such as aerospace, new energy vehicles, and wind turbine blades, where the mechanical properties of structural adhesives are extremely demanding.

[0023] Example The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Unless otherwise specified, the reagents and raw materials used can be purchased commercially. Experimental methods in the following embodiments that do not specify specific conditions are performed according to conventional methods and conditions, or according to the product instructions.

[0024] The raw materials used and their sources in the following examples and comparative examples are as follows: Epoxy resin: Bisphenol A type epoxy resin E-51 (industrial grade, Yueyang Petrochemical); Core-shell structured polymer toughening agent (CSR): (Model: MX-156, Kaneka Chemicals, Japan), core is polybutadiene, shell is polymethyl methacrylate, average particle size 200nm; Liquid carboxyl-terminated nitrile butadiene rubber (CTBN): (Model: Hycar 1300x8, Dow Chemical, USA), used as a comparative toughening agent; Reactive diluent: Butyl glycidyl ether (BGE, industrial grade); Modified polyetheramine curing agent: Mannich modified polyetheramine (model: JEFFAMINE® XTJ-586, Huntsman, USA, amine value ~320 mg KOH / g); Traditional curing agents: Polyamide 650 (industrial grade, amine value ~220 mg KOH / g), Isophorone diamine (IPDA, industrial grade); Accelerator: 2,4,6-Tris(dimethylaminomethyl)phenol (DMP-30, industrial grade); Coupling agent: γ-aminopropyltriethoxysilane (KH-550, industrial grade).

[0025] In the following examples and comparative examples, the testing standards and methods for the obtained samples are as follows: Tensile shear strength: Aluminum alloy (2024-T3) specimens were tested according to GB / T 7124-2008 standard; T-peel strength: Tested on anodized aluminum foil according to GB / T 2791-1995 standard; Impact strength of cantilever beam: Standard impact specimens were prepared according to GB / T 2571-1995 standard; Viscosity: Measured at 25℃ using a rotational viscometer according to GB / T 2794-2013 standard; Glass transition temperature (Tg): determined by differential scanning calorimetry (DSC).

[0026] Example 1 The formulations of each component in this embodiment are as follows: • Component A: 80 parts E-51 epoxy resin, 15 parts core-shell toughening agent (CSR), 5 parts BGE; • Component B: 90 parts modified polyetheramine curing agent, 3 parts DMP-30, and 2 parts KH-550.

[0027] The preparation method of the two-component epoxy resin adhesive in this embodiment is as follows: S1: Preparation of component A: In a reaction vessel, epoxy resin, core-shell structure polymer toughening agent and reactive diluent are added in sequence. Stir at 40°C for 1 hour until the mixture is uniform and transparent. After vacuum degassing, the mixture is discharged and packaged. S2: Preparation of component B: In another reactor, add the modified polyetheramine curing agent, accelerator and coupling agent in sequence, stir at room temperature for 0.5 hours until the mixture is uniform, degas under vacuum and discharge for packaging.

[0028] S3: Mix component A and component B in a weight ratio of A:B = 100:30.

[0029] Example 2 The formulations of each component in this embodiment are as follows: Component A: 70 parts E-51 epoxy resin, 25 parts core-shell toughening agent (CSR), and 5 parts BGE; Component B: 85 parts modified polyetheramine curing agent, 5 parts DMP-30, and 3 parts KH-550.

[0030] The preparation method of the two-component epoxy resin adhesive in this embodiment is as follows: S1: Preparation of component A: In a reaction vessel, epoxy resin, core-shell structure polymer toughening agent and reactive diluent are added in sequence. Stir at 50°C for 2 hours until the mixture is uniform and transparent. After vacuum degassing, the mixture is discharged and packaged. S2: Preparation of component B: In another reactor, add the modified polyetheramine curing agent, accelerator and coupling agent in sequence, stir at room temperature for 1 hour until the mixture is uniform, degas under vacuum and discharge for packaging.

[0031] S3: Mix component A and component B in a weight ratio of A:B = 100:35.

[0032] Example 3 The formulations of each component in this embodiment are as follows: Component A: 85 parts bisphenol F type epoxy resin, 10 parts core-shell toughening agent (CSR), and 5 parts BGE.

[0033] Component B: 88 parts modified polyetheramine curing agent, 2 parts DMP-30, and 3 parts KH-550.

[0034] The preparation method of the two-component epoxy resin adhesive in this embodiment is as follows: S1: Preparation of component A: In a reaction vessel, epoxy resin, core-shell structure polymer toughening agent and reactive diluent are added in sequence. Stir at 60°C for 3 hours until the mixture is uniform and transparent. After vacuum degassing, the mixture is discharged and packaged. S2: Preparation of component B: In another reactor, add the modified polyetheramine curing agent, accelerator and coupling agent in sequence, stir at room temperature for 40 minutes until the mixture is uniform, degas under vacuum and then discharge and package.

[0035] S3: Mix component A and component B in a weight ratio of A:B = 100:32.

[0036] Comparative Example 1 (Traditional Rubber Toughening) The adhesive formulation for this comparative example is as follows: Component A: 80 parts E-51 epoxy resin, 15 parts CTBN, and 5 parts BGE; Component B: 90 parts modified polyetheramine curing agent, 3 parts DMP-30, and 2 parts KH-550.

[0037] The preparation method of this comparative example is as follows: Component A needs to be pre-reacted at 80°C for 2 hours to graft CTBN onto the epoxy resin; the rest is the same as in Example 1. The mixing weight ratio is A:B = 100:30.

[0038] Comparative Example 2 (without toughening agent) The adhesive formulation for this comparative example is as follows: Component A: 95 parts E-51 epoxy resin, 5 parts BGE.

[0039] Component B: 90 parts modified polyetheramine curing agent, 3 parts DMP-30, and 2 parts KH-550.

[0040] The preparation method of this comparative example is as follows: Component A does not contain toughening agents, and the remaining steps are the same as in Example 1, with a mixing weight ratio of A:B = 100:30.

[0041] Comparative Example 3 (Different Curing Agent Systems) The adhesive formulation for this comparative example is as follows: Component A: Same as in Example 1.

[0042] Component B: 100 parts of polyamide 650, 2 parts of DMP-30.

[0043] The preparation method of this comparative example is as follows: The curing agent of component B is different, and the rest of the steps are the same as in Example 1. The mixing weight ratio is A:B = 100:100 (adjusted according to the equivalent amount).

[0044] The adhesives prepared in the above examples were made into samples according to the standard. After being fully cured under curing conditions (80℃ / 2h + 100℃ / 1h), their performance was tested, and the results are shown in Table 1.

[0045] Table 1: Adhesive performance test results of the examples and comparative examples The data clearly show that the embodiments (1-3) of this application are significantly better than all comparative examples in terms of the two key toughness indicators, namely T-peel strength and impact strength.

[0046] Compared to Comparative Example 1, which uses conventional CTBN toughening, the peel strength and impact strength of Example 1 are increased by approximately 51% and 54%, respectively. This demonstrates that core-shell toughening agents are far more efficient than easily segregating liquid rubbers in initiating crazes and shear bands and absorbing energy.

[0047] Compared with Comparative Example 2 (without toughening), although the absolute shear strength decreased slightly (which is a common cost of toughening), the toughness index was improved several times, perfectly solving the core problem of epoxy resin being "high in strength but brittle".

[0048] Compared with Comparative Example 3, which uses a flexible polyamide curing agent, Example 1 showed superior strength and toughness, indicating that the introduction of a single flexible segment cannot replace the synergistic toughening effect of core-shell particles and modified polyetheramine.

[0049] This application successfully achieves a balance between high strength and high toughness. Examples 1 and 3 maintain a high shear strength of 35-40 MPa while also exhibiting excellent toughness and a high Tg. In contrast, Comparative Examples 1 (CTBN) and 3 (polyamide) significantly sacrifice strength and heat resistance (lower Tg) for toughness.

[0050] The component of Example A has a moderate viscosity and is easy to handle. In contrast, Comparative Example 1 requires an additional prepolymerization step, is more complex, and its storage stability may deteriorate due to the prepolymerization reaction.

[0051] Through the detailed examples and comparative data above, it is fully demonstrated that the technical solution provided in this application—using a core-shell structured polymer toughening agent in combination with a specific modified polyetheramine curing agent—can produce a significant synergistic effect, and successfully prepare a two-component epoxy adhesive that achieves the best balance between high strength, high toughness, high heat resistance and good processability. Its comprehensive performance far exceeds that of traditional toughening technologies.

[0052] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A two-component epoxy resin adhesive, characterized in that, It is composed of component A and component B mixed in a weight ratio of 100:(20-50); Wherein, by weight, component A comprises: Epoxy resin: 60-90 parts; Core-shell structured polymer toughening agent: 5-30 parts; Reactive diluent: 1-10 parts; Wherein, by weight, component B comprises: Modified polyetheramine curing agent: 70-95 parts; Accelerator: 0.5-5 parts; Coupling agent: 1-5 parts.

2. The two-component epoxy resin adhesive according to claim 1, characterized in that, The epoxy resin is one or a mixture of two of bisphenol A type epoxy resin and bisphenol F type epoxy resin.

3. The two-component epoxy resin adhesive according to claim 1, characterized in that, The core of the core-shell structured polymer toughening agent is a cross-linked elastomer of polybutadiene and polybutyl acrylate, and the shell is a polymethyl methacrylate or epoxy resin compatible polymer.

4. The two-component epoxy resin adhesive according to claim 1, characterized in that, The active diluent is one or more of butyl glycidyl ether, phenyl glycidyl ether, and 1,4-butanediol diglycidyl ether.

5. The two-component epoxy resin adhesive according to claim 1, characterized in that, The modified polyetheramine curing agent is a product of polyetheramine prepolymerized with epoxy resin or modified with Mannich base. Its amine value is 200-400 mg KOH / g.

6. The two-component epoxy resin adhesive according to claim 1, characterized in that, The accelerator is one or both of 2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine.

7. The two-component epoxy resin adhesive according to claim 1, characterized in that, The coupling agent is one or both of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

8. The two-component epoxy resin adhesive according to claim 1, characterized in that, The epoxy resin is bisphenol A type epoxy resin E-51; The core-shell structure polymer toughening agent is a toughening agent sold by Kaneka Corporation of Japan, with the model number MX-156; The active diluent is butyl glycidyl ether; The modified polyetheramine curing agent is Mannich modified polyetheramine, which is sold by Huntsman Corporation of the United States, and the model is JEFFAMINE® XTJ-586; The accelerator is 2,4,6-tris(dimethylaminomethyl)phenol; The coupling agent is γ-aminopropyltriethoxysilane.

9. A method for preparing a two-component epoxy resin adhesive as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Preparation of Component A At 40-60℃, stir the epoxy resin, core-shell structured polymer toughening agent and reactive diluent for 1-3 hours until the mixture is uniform and transparent. After vacuum degassing, discharge and package. S2: Preparation of component B: Stir the modified polyetheramine curing agent, accelerator and coupling agent at room temperature for 0.5-1 hour until they are evenly mixed. After vacuum degassing, discharge and package.

10. The method as described in claim 9, characterized in that, In step S1, the order of adding materials during the mixing process is as follows: epoxy resin, core-shell structured polymer toughening agent, and reactive diluent are added sequentially. In step S2, the mixing process involves adding the modified polyetheramine curing agent, accelerator, and coupling agent in sequence.

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