High-flexibility tear-resistant epoxy structural adhesive as well as preparation method and application thereof

Abstract

The invention provides a high-flexibility tear-resistant epoxy structural adhesive as well as a preparation method and application thereof. The epoxy structural adhesive is prepared by mixing a component A and a component B, on the basis of the total weight of the component A, the component A comprises the following components in percentage by weight: 34-70% of modified epoxy resin, 5-30% of bisphenol A type epoxy resin, 2-6% of benzyl alcohol, 8-15% of an epoxy reactive diluent, 0.2-1.5% of a defoaming agent, 1-5% of a thixotropic agent, 5-40% of filler and 1-4% of epoxy color paste; on the basis of the total weight of the component B, the component B comprises the following components in percentage by weight: 55-75% of polyether amine, 5-15% of bisphenol A epoxy resin, 5-10% of benzyl alcohol and 10-20% of dodecylphenol. The mixing mass ratio of the component A to the component B is (3.7-7): 1. The modified epoxy resin and the bisphenol A epoxy resin are compounded, and an optimized curing system is combined, so that the flexibility and the tear resistance of the structural adhesive are remarkably improved while the high strength of the epoxy resin is maintained, and the structural adhesive is suitable for structural bonding in the fields of buildings, automobiles, electronics and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of structural adhesive, and particularly relates to a high-flexibility anti-tearing epoxy structural adhesive as well as a preparation method and application thereof. BACKGROUND

[0002] Epoxy structural adhesive has become an indispensable key bonding material in high-end industrial fields such as aerospace, automobile manufacturing, wind power generation and building structure, due to its excellent mechanical properties, outstanding durability, good chemical corrosion resistance and wide adaptability to various substrates (such as metal, concrete, composite materials, etc.). Its curing mechanism depends on the crosslinking of epoxy groups and curing agents to form a three-dimensional network structure, thereby giving the material extremely high rigid bonding strength.

[0003] However, the traditional epoxy resin system often exhibits high hardness (Shore D hardness is generally about 80) and high brittleness due to high crosslinking density and limited chain segment movement. This characteristic results in poor impact resistance, insufficient fatigue resistance and low elongation at break. In actual application, especially in the bonding of dissimilar materials with dynamic load, vibration impact or thermal expansion coefficient difference, stress concentration is easily generated in the material, causing microcracks and rapid expansion, and ultimately leading to sudden brittle fracture of the bonded joint at much lower than the theoretical load, which poses a significant safety hazard.

[0004] To break through the brittleness bottleneck of epoxy resin, the industry has developed various toughening technologies, mainly including liquid rubber toughening, thermoplastic polymer toughening, core-shell polymer (CSP) toughening and nano-particle toughening. Although these methods have improved the toughness of the material to some extent, they generally face the contradiction between strength and toughness: the modification of toughness often accompanies the decrease of stiffness, strength and heat resistance. More importantly, as a key indicator of the material's ability to resist crack propagation, anti-tearing property requires the adhesive not only to have high elongation at break, but also to have high tear strength to effectively absorb and disperse energy. Existing toughened epoxy adhesive still often shows defects such as sudden failure and insufficient energy dissipation capacity under continuous or repeated tearing stress.

[0005] In view of this, the present application provides a high-flexibility anti-tearing epoxy structural adhesive as well as a preparation method and application thereof, which can effectively solve the contradiction between strength and toughness, significantly improve the elongation at break and anti-tearing strength, and maintain the inherent high strength, high modulus and good heat resistance of epoxy resin. SUMMARY

[0006] In view of the brittleness, insufficient anti-tearing property of traditional epoxy structural adhesive and the difficulty of existing toughening technologies to balance strength and toughness, the present application provides a high-flexibility anti-tearing epoxy structural adhesive as well as a preparation method and application thereof to solve the above technical defects.

[0007] The technical scheme adopted by the present application to solve the technical problems is:

[0008] In a first aspect, the present application provides a high-flexibility tear-resistant epoxy structural adhesive, which is composed of a mixture of component A and component B.

[0009] The component A comprises the following components by weight percentage based on the total weight of the component A:

[0010] The modified epoxy resin is 34-70%, the bisphenol A type epoxy resin is 5-30%, the benzyl alcohol is 2-6%, the epoxy active diluent is 8-15%, the defoaming agent is 0.2-1.5%, the thixotropic agent is 1-5%, the filler is 5-40%, and the epoxy color paste is 1-4%.

[0011] The component B comprises the following components by weight percentage based on the total weight of the component B:

[0012] The polyether amine is 55-75%, the bisphenol A type epoxy resin is 5-15%, the benzyl alcohol is 5-10%, and the dodecyl phenol is 10-20%.

[0013] Preferably, the mixing mass ratio of the component A and the component B is (3.7-7):1.

[0014] Preferably, the defoaming agent is composed of an organic silicon defoaming agent and a polymer defoaming agent, wherein the content of the organic silicon defoaming agent is 0.1-1% based on the total weight of the component A, the content of the polymer defoaming agent is 0.1-0.5%, and the total content of the defoaming agent is 0.2-1.5%.

[0015] Preferably, the epoxy active diluent is any one or a mixture of several of benzyl glycidyl ether, butyl glycidyl ether, and C12-14 alkyl glycidyl ether; and the filler is any one or a mixture of several of silicon powder, heavy calcium powder, talc powder, and barium sulfate.

[0016] Preferably, the thixotropic agent is fumed silica or bentonite.

[0017] Preferably, the modified epoxy resin is a polyurethane modified epoxy resin or a polyether modified epoxy resin.

[0018] Preferably, the polyurethane modified epoxy resin has an epoxy equivalent weight of 410-470 g / eq and a viscosity of 20,000-60,000 mPa·s; and the polyether modified epoxy resin has an epoxy equivalent weight of 360-390 g / eq and a viscosity of 6,000-15,000 mPa·s.

[0019] Preferably, the epoxy color paste comprises the following components by weight percentage based on the total weight of the epoxy color paste:

[0020] Bisphenol A epoxy resin 30-50%, epoxy reactive diluent 5-10%, dispersant 2-3%, titanium dioxide 39.5-61%, and carbon black 0.5-2%.

[0021] In a second aspect, the present application provides a method for preparing the high-flexibility tear-resistant epoxy structural adhesive according to any one of the above, comprising the following steps:

[0022] (1) Preparation of component A: according to the ratio, add modified epoxy resin, bisphenol A epoxy resin, benzyl alcohol and epoxy reactive diluent into the reaction kettle, stir and mix uniformly at 40-60℃, then add defoaming agent, thixotropic agent, filler and epoxy color paste, continue to disperse until the fineness is <30 microns, and then filter the material through a 120 mesh screen;

[0023] (2) Preparation of component B: according to the ratio, first disperse polyether amine into the reaction kettle; then mix benzyl alcohol and bisphenol A epoxy resin uniformly, and slowly add them into the reaction kettle, stir and disperse at 50-60℃, and keep the reaction for 2-4 hours; finally, add dodecyl phenol and continue to stir until uniform;

[0024] (3) Mixing and curing: mix component A obtained in step (1) and component B obtained in step (2) according to the mass ratio (3.7-7):1, stir uniformly, and cure at room temperature to obtain the epoxy structural adhesive.

[0025] In a third aspect, the present application provides the use of the high-flexibility tear-resistant epoxy structural adhesive according to any one of the above as a structural adhesive material.

[0026] In summary, compared with the prior art, the high-flexibility tear-resistant epoxy structural adhesive, its preparation method and use provided by the present application have the following beneficial effects:

[0027] (1) By using polyurethane modified epoxy resin / polyether modified epoxy resin with specific epoxy equivalent and viscosity range and bisphenol A epoxy resin for compounding, the flexibility of polyurethane segment and the high strength characteristics of epoxy resin network are ingeniously combined, so that the structural adhesive after curing can significantly improve the elongation at break while still maintaining high bending strength, effectively solving the long-existing "strength-toughness" contradiction in the field of epoxy structural adhesives.

[0028] (2) By optimizing the A component and B component system and their mixing ratio of (3.7-7):1, especially the cooperation of specific proportions of polyether amine, bisphenol A epoxy resin and dodecyl phenol in the B component, the curing reaction rate and crosslinking network structure are synergistically controlled, not only ensuring the operation time, but also making the cured product obtain excellent tear resistance and energy dissipation capacity, effectively inhibiting the initiation and expansion of cracks, and overcoming the common sudden failure defect in the existing toughening technology.

[0029] (3) The specific selection of the type, particle size and amount of the filler (preferably silicon powder) and the thixotropic agent (fumed silica / bentonite) effectively improves the thixotropic properties and anti-settling stability of the colloid on the basis of ensuring good fluidity and workability of the system, and further synergistically improves the final mechanical properties and durability of the material through the physical reinforcing effect on the cured network structure.

[0030] (4) The entire formulation system is reasonably designed, the preparation process is simple, the conditions are mild (main links can be completed at room temperature to 60°C), no special equipment is needed, it is suitable for large-scale production, and the structural adhesive prepared has excellent comprehensive performance, and has broad prospects in the structural bonding applications in the fields of building, automobile, electronics and aerospace. BRIEF DESCRIPTION OF DRAWINGS

[0031] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings:

[0032] Figure 1 is a preparation method flow chart of the high-flexibility tear-resistant epoxy structural adhesive of the present application;

[0033] Figure 2 is a cured sample morphology display diagram of the epoxy structural adhesive;

[0034] Figure 3 is a flexibility bending test site diagram of the epoxy structural adhesive;

[0035] Figure 4 is a stone splicing application diagram of the epoxy structural adhesive;

[0036] Figure 5 is a bending performance demonstration diagram of the epoxy structural adhesive;

[0037] Figure 6 is a detail diagram of the edge bonding of the epoxy structural adhesive and the composite material;

[0038] Figure 7 is a tear-resistant flexibility verification diagram of the epoxy structural adhesive. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below with reference to the accompanying drawings and examples. It can be understood that the specific examples described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0040] It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and examples.

[0041] In a first aspect, the present application provides a high-flexibility tear-resistant epoxy structural adhesive, which is composed of a mixture of component A and component B.

[0042] The component A includes the following components by weight percentage based on the total weight of the component A:

[0043] modified epoxy resin 34-70%, bisphenol A type epoxy resin 5-30%, benzyl alcohol 2-6%, epoxy reactive diluent 8-15%, silicone defoaming agent 0.1-1%, polymeric defoaming agent 0.1-0.5%, thixotropic agent 1-5%, filler 5-40%, and epoxy color paste 1-4%;

[0044] The component B includes the following components by weight percentage based on the total weight of the component B:

[0045] polyether amine 55-75%, bisphenol A type epoxy resin 5-15%, benzyl alcohol 5-10%, and dodecyl phenol 10-20%.

[0046] The mixing mass ratio of the component A and the component B is (3.7-7):1.

[0047] In specific embodiments, the epoxy reactive diluent is any one or a mixture of several of benzyl glycidyl ether, butyl glycidyl ether, and C12-14 alkyl glycidyl ether. The filler is any one or a mixture of several of silicon powder, heavy calcium powder, talc powder, and barium sulfate. The preferred filler is silicon powder with a particle size of 5-30 microns (filler mesh number 600-1500) and a color paste fineness of <30 microns. The thixotropic agent is fumed silica with a particle size of 10-20 nm. The modified epoxy resin is polyurethane modified epoxy resin or polyether modified epoxy resin. The polyurethane modified epoxy resin has an epoxy equivalent weight of 410-470 g / eq and a viscosity of 20,000-60,000 mPa·s; the polyether modified epoxy resin has an epoxy equivalent weight of 360-390 g / eq and a viscosity of 6,000-15,000 mPa·s. It should be understood by those skilled in the art that the polyurethane modified epoxy resin / polyether modified epoxy resin is not limited to the type used in the embodiments, and other polyurethane modified epoxy resins / polyether modified epoxy resins with similar epoxy equivalent weight and viscosity can also achieve the present application.

[0048] The epoxy color paste includes the following components by weight percentage based on the total weight of the epoxy color paste:

[0049] bisphenol A type epoxy resin 30-50%, epoxy reactive diluent 5-10%, dispersant 2-3%, titanium dioxide 39.5-61%, and carbon black 0.5-2%. The titanium dioxide includes rutile titanium dioxide and anatase titanium dioxide.

[0050] In a second aspect, the present application provides a preparation method of the high-flexibility tear-resistant epoxy structural adhesive as described above, which comprises the following steps as shown in the figure: Figure 1

[0051] (1) Preparation of component A: according to the proportion, the modified epoxy resin, bisphenol A type epoxy resin, benzyl alcohol and benzyl glycidyl ether are added into a reaction kettle, stirred and mixed uniformly at 40-60℃, then the defoaming agent, thixotropic agent, filler and epoxy color paste are added, and the dispersion is continued until the fineness is less than 30 microns, and then the material is filtered out by a 120 mesh screen cloth;

[0052] (2) Preparation of component B: according to the proportion, the polyether amine is first added into a reaction kettle for dispersion; then the benzyl alcohol and bisphenol A type epoxy resin are mixed uniformly and slowly added into the reaction kettle, stirred and dispersed at 50-60℃ and reacted for 2-4 hours; finally, the dodecyl phenol is added and stirred until uniform;

[0053] (3) Mixing and curing: the component A obtained in step (1) and the component B obtained in step (2) are mixed according to the mass ratio (3.7-7):1, stirred uniformly, and cured at room temperature to obtain the epoxy structural adhesive.

[0054] In a third aspect, the present application provides an application of the high-flexibility tear-resistant epoxy structural adhesive as described above as a structural adhesive material.

[0055] ​In the preparation method of the present application, moderate stirring / dispersion refers to stirring at a speed of 300-600 RPM, and high-speed dispersion refers to stirring at a speed of 1000-1500 RPM. ECU-4500 is a polyurethane modified epoxy resin from Hunan Sailve New Material Science and Technology Co., Ltd., which is a light yellow transparent liquid with a colority of <3G, volatile matter of ≤1%, an epoxy equivalent weight of 410-470 g / eq, and a viscosity of 20000-60000 (25℃ cps); HQ-4000 is a polyether modified epoxy resin from Hunan Sailve New Material Science and Technology Co., Ltd., which is a light white transparent liquid with a colority of ≤4G, volatile matter of ≤1%, an epoxy equivalent weight of 360-390 g / eq, and a viscosity of 6000-15000 (25℃ cps). 128 is a bisphenol A type epoxy resin from Nan Ya Plastics Corporation; BA is benzyl alcohol from Sanmu Group; 692 is benzyl glycidyl ether from Green Home Chemical Co., Ltd.; TEGO-900 is an organic silicon defoaming agent from Evonik Industries AG; BYK-057 is a polymeric defoaming agent from BYK-Chemie GmbH; BYK-163 is a dispersant from BYK-Chemie GmbH; AEROSIL 200 is fumed silica from Evonik Industries AG with a particle size of 10-20 nm; 2377 is rutile titanium dioxide from DKS Co., Ltd.; MA-100 is carbon black from Mitsubishi Chemical Corporation; 8100 is polyetheramine from Wanhua Chemical Group Co., Ltd.; 12D is dodecyl phenol from He Ma Trading Co., Ltd.; 3077 is polyetheramine from Huntsman Corporation; 650 is polyamide from BASF SE; 3680 is alicyclic amine from Evonik Industries AG; and silicon powder is 600 mesh silicon powder from Huater Chemical Co., Ltd. with a particle size of 5-15 μm.

[0056] It should be noted that the following examples are specific examples, although all use fumed silica as a thixotropic agent, based on the similarity in mechanism of action (such as forming a network structure through hydrogen bonds) with bentonite (such as organic bentonite), the use of bentonite at the same amount can also obtain the desired thixotropic properties and anti-settling effect of the present application.

[0057] Regarding the epoxy reactive diluent: the epoxy reactive diluent, including butyl glycidyl ether, C12-14 alkyl glycidyl ether, etc., is an alkyl glycidyl ether active diluent as the benzyl glycidyl ether used in the examples. They have good compatibility with epoxy resins, participate in the curing reaction and can effectively adjust the viscosity of the system. Based on their similar chemical structure (containing epoxy groups and alkyl chains) and functionality, at the same or similar amount (such as 8-15%), one skilled in the art can expect that they can also play a role in dilution and toughening, and obtain similar high flexibility and tear resistance as the examples of the present application.

[0058] Regarding fillers: the fillers, including heavy calcium powder, talc powder, barium sulfate, etc., are all inorganic fillers, same as the silica powder used in the examples. They mainly play the role of filling, compounding, reducing cost, and adjusting physical properties (such as hardness, modulus) in the system. These fillers have similar chemical inertness and physical form (powder), and within similar particle sizes (such as 5-30 microns) and amounts (such as 5-40%), a person skilled in the art can reasonably expect that they can replace silica powder to achieve the technical effects of the present application, and the specific mechanical property indicators can fluctuate within a reasonable range of the data in the examples.

[0059] Regarding titanium dioxide: the titanium dioxide (titanium dioxide) includes rutile and anatase. The rutile titanium dioxide with higher hiding power, weather resistance and stability is preferably used in the examples to maximize the long-term durability of the structural adhesive. However, rutile and anatase titanium dioxide are the same in chemical nature (both are TiO2) and basic function as white pigment. In application scenarios where the requirement for weather resistance is not extreme, based on cost and other factors, a person skilled in the art can reasonably expect that anatase titanium dioxide with the same or similar amount (such as 39.5-61%) can also meet the basic requirements of the present application for color hiding power and obtain similar mechanical properties, and its specific performance will be within the data range of the examples.

[0060] Example 1

[0061] Preparation of component A: based on the total weight of component A, the following materials were prepared according to the following proportions: polyurethane modified epoxy resin ECU-4500 (epoxy equivalent weight 410, viscosity 30000 mPa·s) 65%, bisphenol A type epoxy resin 128 9%, benzyl alcohol BA 3%, benzyl glycidyl ether 692 10%, silicone defoamer TEGO-900 0.5%, polymer defoamer BYK-057 0.3%, fumed silica AEROSIL 200 2%, silica powder 7.2%, self-made epoxy color paste 3%.

[0062] First, the epoxy color paste was prepared: based on the total weight of the epoxy color paste, 45% bisphenol A type epoxy resin 128, 8% benzyl glycidyl ether 692, and 2.5% dispersant BYK-163 were sequentially added to the stirring cylinder and dispersed at medium speed for 10 minutes; then 43% rutile titanium dioxide 2377 and 1.5% carbon black MA-100 were added and dispersed at high speed for 25 minutes; finally, a three-roll mill was used for grinding to a fineness of <30 microns to obtain the epoxy color paste.

[0063] Then the preparation of A component: ECU-4500, 128 resin, BA, 692 were added into the reactor in turn, stirring at 50 ℃ for 20 minutes; then TEGO-900, BYK-057, AEROSIL 200, silicon powder and self-made epoxy color paste were added, and continue to stir at high speed for 25 minutes, disperse until the fineness <30 microns, 120 mesh screen filter out the material.

[0064] B component preparation: based on the total weight of B component, the following ratio of raw materials: polyether amine 8100 70%, bisphenol A type epoxy resin 128 6%, benzyl alcohol BA 8%, dodecyl phenol 12D 16%. First, 8100 was added to the reactor, and the stirring was started; then BA and 128 resin were mixed evenly, and then slowly added to the reactor, dispersed at medium speed for 40 minutes, the temperature was controlled at 50-60 ℃, and the reaction was kept for 3 hours; finally, 12D was slowly added, and dispersed at medium speed for 40 minutes to prepare B component.

[0065] When used, A component and B component were mixed in a mass ratio of 5:1, stirred evenly, and cured at room temperature (23±2 ℃) for 7 days to obtain an epoxy structural adhesive sample.

[0066] Example 2

[0067] A component preparation: based on the total weight of A component, the following ratio of raw materials: polyurethane modified epoxy resin ECU-4500 (epoxy equivalent weight 470 g / eq, viscosity 60000 mPa·s) 40%, bisphenol A type epoxy resin 128 9%, benzyl alcohol BA 3%, benzyl glycidyl ether 692 10%, silicone defoamer TEGO-900 0.5%, polymer defoamer BYK-057 0.3%, fumed silica AEROSIL 200 2%, silicon powder 32.2%, and self-made epoxy color paste 3%.

[0068] Epoxy color paste preparation: based on the total weight of epoxy color paste, 48.5% bisphenol A type epoxy resin 128, 8% benzyl glycidyl ether 692, and 2.5% dispersant BYK-163 were added into the stirring cylinder in turn, and dispersed at medium speed for 10 minutes; then 39.5% rutile titanium dioxide 2377 and 1.5% carbon black MA-100 were added, and dispersed at high speed for 25 minutes; finally, the three-roll mill was used to grind to a fineness <30 microns to prepare the epoxy color paste.

[0069] A component preparation: ECU-4500, 128 resin, BA, 692 were added into the reactor in turn, stirring at 40 ℃ for 20 minutes; then TEGO-900, BYK-057, AEROSIL 200, silicon powder and self-made epoxy color paste were added, and continue to stir at high speed for 25 minutes, disperse until the fineness <30 microns, 120 mesh screen filter out the material.

[0070] Preparation of B component: based on the total weight of B component, the following materials were prepared: polyether amine 8100 55%, bisphenol A type epoxy resin 128 15%, benzyl alcohol BA 10%, dodecyl phenol 12D 20%. First, 8100 was added to the reaction kettle and moderate stirring was started; then BA and 128 resin were mixed uniformly and slowly added to the reaction kettle, moderate dispersion for 40 minutes, temperature control at 50-60°C, reaction for 3 hours; finally, 12D was slowly added, moderate dispersion for 40 minutes, to obtain B component.

[0071] In use, A component and B component were mixed in a mass ratio of 7:1, stirred uniformly, and cured at room temperature (23±2°C) for 7 days to obtain an epoxy structural adhesive sample.

[0072] Example 3

[0073] Preparation of A component: based on the total weight of A component, the following materials were prepared: polyurethane modified epoxy resin ECU-4500 (epoxy equivalent weight 450 g / eq, viscosity 20000 mPa·s) 40%, bisphenol A type epoxy resin 128 25%, benzyl alcohol BA 3%, benzyl glycidyl ether 692 10%, silicone defoaming agent TEGO-900 0.5%, polymer defoaming agent BYK-057 0.3%, fumed silica AEROSIL 200 2%, silicon powder 16.2%, and self-made epoxy color paste 3%.

[0074] Preparation of epoxy color paste: based on the total weight of epoxy color paste, 31.5% bisphenol A type epoxy resin 128, 5% benzyl glycidyl ether 692, and 2% dispersant BYK-163 were sequentially added to a stirring cylinder and moderately dispersed for 10 minutes; then 61% rutile titanium dioxide 2377 and 0.5% carbon black MA-100 were added and high-speed dispersed for 25 minutes; finally, a three-roll mill was used for grinding to a fineness of <30 microns to obtain the epoxy color paste.

[0075] Preparation of A component: ECU-4500, 128 resin, BA, and 692 were sequentially added to a reaction kettle and moderately stirred at 60°C for 20 minutes; then TEGO-900, BYK-057, AEROSIL 200, silicon powder, and self-made epoxy color paste were added and high-speed stirred for 25 minutes until the fineness was <30 microns, and the material was filtered through a 120 mesh screen.

[0076] Preparation of B component: based on the total weight of B component, the following materials were prepared: polyetheramine 8100 75%, bisphenol A type epoxy resin 128 6%, benzyl alcohol BA 8%, dodecyl phenol 12D 11%. First, 8100 was added to the reaction kettle and moderate stirring was started; then BA and 128 resin were mixed uniformly and slowly added to the reaction kettle, moderate dispersion for 40 minutes, temperature control at 50-60°C, reaction for 3 hours; finally, 12D was slowly added, moderate dispersion for 40 minutes, to obtain B component.

[0077] In use, A component and B component were mixed in a mass ratio of 3.7:1, stirred uniformly, and cured at room temperature (23±2°C) for 7 days to obtain an epoxy structural adhesive sample.

[0078] Example 4

[0079] Preparation of A component: based on the total weight of A component, the following materials were prepared: polyether modified epoxy resin HQ-4000 (epoxy equivalent weight 360 g / eq, viscosity 6000 mPa·s) 40%, bisphenol A type epoxy resin 128 9%, benzyl alcohol BA 3%, benzyl glycidyl ether 692 10%, silicone defoaming agent TEGO-900 0.5%, polymer defoaming agent BYK-057 0.3%, fumed silica AEROSIL 200 2%, silicon powder 32.2%, and self-made epoxy color paste 3%.

[0080] Preparation of epoxy color paste: based on the total weight of epoxy color paste, 45% bisphenol A type epoxy resin 128, 8% benzyl glycidyl ether 692, and 2.5% dispersant BYK-163 were sequentially added to a stirring cylinder and moderately dispersed for 10 minutes; then 43% rutile titanium dioxide 2377 and 1.5% carbon black MA-100 were added and high-speed dispersed for 25 minutes; finally, a three-roll mill was used for grinding to a fineness of <30 microns to obtain the epoxy color paste.

[0081] Preparation of A component: HQ-4000, 128 resin, BA, and 692 were sequentially added to a reaction kettle and moderately stirred at 50°C for 20 minutes; then TEGO-900, BYK-057, AEROSIL 200, silicon powder, and self-made epoxy color paste were added and high-speed stirring was continued for 25 minutes until the fineness was <30 microns, and the material was filtered through a 120 mesh screen

[0082] Preparation of B component: based on the total weight of B component, the following materials were prepared: polyetheramine 8100 65%, bisphenol A type epoxy resin 128 15%, benzyl alcohol BA 10%, dodecyl phenol 12D 10%. First, 8100 was added to the reaction kettle and moderate stirring was started; then BA and 128 resin were mixed uniformly and slowly added to the reaction kettle, moderate dispersion for 40 minutes, temperature control at 50-60°C, reaction for 3 hours; finally, 12D was slowly added, moderate dispersion for 40 minutes, to obtain B component.

[0083] In use, A component and B component were mixed in a mass ratio of 6.6:1, stirred uniformly, and cured at room temperature (23±2°C) for 7 days to obtain an epoxy structural adhesive sample.

[0084] Example 5

[0085] Preparation of A component: based on the total weight of A component, the following materials were prepared: polyether modified epoxy resin HQ-4000 (epoxy equivalent weight 390 g / eq, viscosity 15000 mPa·s) 34%, bisphenol A type epoxy resin 128 20%, benzyl alcohol BA 6%, benzyl glycidyl ether 692 15%, silicone defoaming agent TEGO-900 1%, polymer defoaming agent BYK-057 0.5%, fumed silica AEROSIL 200 5%, silicon powder 14.5%, and self-made epoxy color paste 4%.

[0086] Preparation of epoxy color paste: based on the total weight of epoxy color paste, 50% bisphenol A type epoxy resin 128, 5% benzyl glycidyl ether 692, and 2% dispersant BYK-163 were sequentially added to a stirring cylinder and moderately dispersed for 10 minutes; then 41% rutile titanium dioxide 2377 and 2% carbon black MA-100 were added and high-speed dispersed for 25 minutes; finally, a three-roll mill was used for grinding to a fineness of <30 microns to obtain the epoxy color paste.

[0087] Preparation of A component: HQ-4000, 128 resin, BA, and 692 were sequentially added to a reaction kettle and stirred at a moderate speed for 20 minutes at 50°C; then TEGO-900, BYK-057, AEROSIL 200, silicon powder, and self-made epoxy color paste were added and continued to be stirred at a high speed for 25 minutes until the fineness was <30 microns, and then the material was filtered through a 120 mesh screen.

[0088] Preparation of B component: based on the total weight of B component, the following materials were prepared: polyetheramine 8100 63%, bisphenol A type epoxy resin 128 10%, benzyl alcohol BA 7%, dodecyl phenol 12D 20%. First, 8100 was added to the reaction kettle and moderate stirring was started; then BA and 128 resin were mixed uniformly and slowly added to the reaction kettle, moderate dispersion for 40 minutes, temperature control at 50-60°C, reaction for 3 hours; finally, 12D was slowly added, moderate dispersion for 40 minutes, to obtain B component.

[0089] In use, A component and B component were mixed in a mass ratio of 5:1, stirred uniformly, and cured at room temperature (23±2°C) for 7 days to obtain an epoxy structural adhesive sample.

[0090] Example 6

[0091] Preparation of A component: based on the total weight of A component, the following materials were prepared: polyether modified epoxy resin HQ-4000 (epoxy equivalent weight 380 g / eq, viscosity 10000 mPa·s) 70%, bisphenol A type epoxy resin 128 5%, benzyl alcohol BA 2%, benzyl glycidyl ether 692 8%, silicone defoaming agent TEGO-900 0.1%, polymer defoaming agent BYK-057 0.1%, fumed silica AEROSIL 200 1%, silicon powder 12.8%, and self-made epoxy color paste 1%.

[0092] Preparation of epoxy color paste: based on the total weight of epoxy color paste, 30% bisphenol A type epoxy resin 128, 10% benzyl glycidyl ether 692, and 3% dispersant BYK-163 were sequentially added to a stirring cylinder and moderately dispersed for 10 minutes; then 56.5% rutile titanium dioxide 2377 and 0.5% carbon black MA-100 were added and high-speed dispersed for 25 minutes; finally, a three-roll mill was used for grinding to a fineness of <30 microns to obtain the epoxy color paste.

[0093] Preparation of A component: HQ-4000, 128 resin, BA, and 692 were sequentially added to a reaction kettle and moderately stirred at 50°C for 20 minutes; then TEGO-900, BYK-057, AEROSIL 200, silicon powder, and self-made epoxy color paste were added and high-speed stirring was continued for 25 minutes until the fineness was <30 microns, and the material was filtered through a 120 mesh screen.

[0094] Preparation of B component: based on the total weight of B component, the following materials were prepared: polyetheramine 8100 70%, bisphenol A type epoxy resin 128 5%, benzyl alcohol BA 5%, dodecyl phenol 12D 20%. First, 8100 was added to the reaction kettle and moderate stirring was started; then BA and 128 resin were mixed uniformly and slowly added to the reaction kettle, moderate dispersion for 40 minutes, temperature control at 50-60°C, reaction for 3 hours; finally, 12D was slowly added, moderate dispersion for 40 minutes, to obtain B component.

[0095] In use, A component and B component were mixed in a mass ratio of 5:1, stirred uniformly, and cured at room temperature (23±2°C) for 7 days to obtain an epoxy structural adhesive sample.

[0096] Comparative Example

[0097] The commercially available Araldite 2015-1 (Huntsman Group) epoxy structural adhesive was used as a control example in this comparative example. The performance test was carried out after mixing and using according to the product instruction and curing for 7 days under the same environmental conditions (23±2°C).

[0098] The epoxy structural adhesives prepared in Examples 1-6 and the comparative example were tested for performance, and the tensile strength and elongation at break were tested according to the national standard GB / T 7124-2008, the bending strength and flexural modulus were tested according to GB / T 9341-2008, the Shore A hardness was tested according to GB / T 531.1-2008, the shear strength was tested according to GB / T 7122-2008, and the peel strength was tested according to GB / T 2790-1995. The pot life and surface drying time were tested according to the actual use conditions of the product. The results are shown in the following table:

[0099]

[0100]

[0101] From the performance test data of Examples 1-6 and the comparative example, it can be seen that the high-flexibility tear-resistant epoxy structural adhesive provided by the present application significantly improves the elongation at break (10-66%) while maintaining a relatively high bending strength (47-72 MPa), and also maintains a relatively low flexural modulus (3.8-10 MPa), achieving a good balance between rigidity and toughness. The comparative example has a relatively high tensile strength and hardness, but the elongation at break is extremely low (4.2%), and the flexural modulus is as high as 1800 MPa, showing the typical characteristics of a brittle material. Among them, Examples 1-2 and 4-6 maintain moderate mechanical strength while the elongation at break is more than 50%. Example 3 obtains a relatively high hardness (85 Shore A) and tensile strength (9 MPa) by adjusting the resin ratio, which is suitable for application scenarios with high rigidity requirements.

[0102] Figures 2-7 The comprehensive application performance of the high-flexibility epoxy structural adhesive of the present application is intuitively demonstrated. As shown in Figure 2 the cured adhesive sample is uniform in texture and smooth in surface, embodying its good compatibility and complete curing. Figure 3 The characteristic of the adhesive layer remaining unbroken under large deformation is vividly verified by the manual bending test, which confirms its elongation at break of up to 66%. Figure 4 The stone plate splicing test of the epoxy structural adhesive shown directly proves the excellent tear resistance of the structural adhesive at the interface, which can effectively resist crack propagation. Figure 5 The bending performance demonstration further supports its bending strength of 70 MPa, showing that the adhesive has both toughness and supporting force when bearing load. Figure 6 The delicate morphology of the composite material edge bonding indicates that the adhesive can still form a dense and defect-free bonding interface at the interface of heterogeneous materials. Figure 7 The tear resistance test shows that the adhesive can maintain structural integrity when subjected to repeated stretching, fully embodying the balance of high flexibility and tear resistance. These images collectively confirm from different angles that the epoxy structural adhesive described in the present application successfully realizes the effective unification of high flexibility and high strength, tear resistance, and can meet the high reliability requirements of structural adhesive materials under dynamic load in many fields such as construction, automobiles, electronics, etc.

[0103] The above examples fully demonstrate that the present application successfully solves the technical problem of the "strength-toughness" trade-off of traditional epoxy structural adhesives through specific formulation system design, especially the use of polyurethane modified epoxy resin / polyether modified epoxy resin with specific curing agent system. Test results show that the epoxy structural adhesive of the present application is particularly suitable for structural bonding in the fields of building structures, automobile manufacturing, electronic packaging, and aerospace, and can effectively disperse stress and avoid sudden brittle fracture in application scenarios under dynamic load or with thermal expansion difference, greatly improving the safety and durability of the bonded structure.

[0104] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with the technical features disclosed in the present application (but not limited to) having similar functions to form technical solutions.

Claims

1. A high flexibility tear resistant epoxy structural adhesive, characterized in that, The epoxy structural adhesive is composed of A component and B component mixed together; The A component includes the following components by weight percentage based on the total weight of the A component: Modified epoxy resin 34-70%, bisphenol A type epoxy resin 5-30%, benzyl alcohol 2-6%, epoxy active diluent 8-15%, defoaming agent 0.2-1.5%, thixotropic agent 1-5%, filler 5-40% and epoxy color paste 1-4%; The B component includes the following components by weight percentage based on the total weight of the B component: Polyether amine 55-75%, bisphenol A type epoxy resin 5-15%, benzyl alcohol 5-10% and dodecyl phenol 10-20%.

2. The high-flexibility, tear-resistant epoxy structural adhesive of claim 1, wherein, The mixing mass ratio of the A component and the B component is (3.7-7):

1.

3. The high-flex high tear strength epoxy structural adhesive of claim 1, wherein, The defoaming agent is composed of silicone defoaming agent and polymer defoaming agent, wherein the content of the silicone defoaming agent is 0.1-1% and the content of the polymer defoaming agent is 0.1-0.5% based on the total weight of the A component, and the total content of the defoaming agent is 0.2-1.5%.

4. The high-flex high tear strength epoxy structural adhesive of claim 1, wherein, The epoxy active diluent is any one or mixture of several of benzyl glycidyl ether, butyl glycidyl ether and C12-14 alkyl glycidyl ether; the filler is any one or mixture of several of silicon powder, heavy calcium powder, talc powder and barium sulfate.

5. The high-flex high tear strength epoxy structural adhesive of claim 1, wherein, The thixotropic agent is fumed silica or bentonite.

6. The high-flex high tear strength epoxy structural adhesive of claim 1, wherein, The modified epoxy resin is polyurethane modified epoxy resin or polyether modified epoxy resin.

7. The high-flex high tear strength epoxy structural adhesive of claim 6, wherein, The polyurethane modified epoxy resin has epoxy equivalent of 410-470 g / eq and viscosity of 20000-60000 mPa·s; the polyether modified epoxy resin has epoxy equivalent of 360-390 g / eq and viscosity of 6000-15000 mPa·s.

8. The high-flex high tear strength epoxy structural adhesive of claim 1, wherein, The epoxy color paste includes the following components by weight percentage based on the total weight of the epoxy color paste: Bisphenol A type epoxy resin 30-50%, epoxy active diluent 5-10%, dispersant 2-3%, titanium white powder 39.5-61% and carbon black 0.5-2%.

9. A process for the preparation of a high flexibility tear resistant epoxy structural adhesive as claimed in any one of claims 1 to 8, characterized in that, The method includes the following steps: (1) Preparation of the A component: the modified epoxy resin, bisphenol A type epoxy resin, benzyl alcohol and epoxy active diluent are added into a reaction kettle according to the proportion, stirred and mixed uniformly at 40-60℃, then the defoaming agent, thixotropic agent, filler and epoxy color paste are added, continue to disperse until the fineness is less than 30 microns, and then filter the material through a 120 mesh screen; (2) Preparation of the B component: the polyether amine is first added into a reaction kettle for dispersion; then the benzyl alcohol and bisphenol A type epoxy resin are mixed uniformly and slowly added into the reaction kettle, stirred and dispersed at 50-60℃ and kept for 2-4 hours for reaction; finally the dodecyl phenol is added and continue to stir until uniform; (3) Mixing and curing: the A component obtained in step (1) and the B component obtained in step (2) are mixed according to the mass ratio of (3.7-7):1, stirred uniformly, cured at room temperature, and the epoxy structural adhesive is obtained.

10. Application of the high flexibility and tear resistance epoxy structural adhesive as claimed in any one of claims 1-8 as a structural adhesive material.

Images