High-modulus epoxy resin-based structural adhesive material and preparation method thereof

Abstract

The invention provides a high-modulus epoxy resin-based structural adhesive material and a preparation method thereof, and relates to the technical field of adhesive preparation. The epoxy resin-based structural adhesive material comprises the following raw materials in parts by weight: 40-60 parts of epoxy resin, 15-30 parts of a curing agent, 5-15 parts of a nano reinforcing filler, 3-8 parts of a flexibilizer, 2-4 parts of an auxiliary agent and 0.5-2 parts of an accelerant. The flexibilizer is prepared from carboxyl-terminated nitrile rubber and ethylene propylene diene monomer in a mass ratio of (1-3): 1, and the nano reinforcing filler is prepared from surface-modified nano silicon dioxide, surface-treated nano calcium carbonate and modified multi-walled carbon nanotubes in a mass ratio of (1-2): 1: (0.8-1.2). The preparation method is simple and easy to implement, all the components can be evenly dispersed, no harmful substance is generated in the preparation process, the obtained structural adhesive has the excellent bonding performance, meanwhile, the high modulus characteristic is achieved, the requirements for high-strength and high-modulus structural adhesives in the high-end fields of aerospace, automobile manufacturing and the like can be met, and the structural adhesive has good application prospects. Good application prospects are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesive preparation, in particular to a high modulus epoxy resin-based structural adhesive material and a preparation method thereof. BACKGROUND

[0002] Epoxy resin, in a broad sense, refers to a high molecular prepolymer containing two or more epoxy groups and capable of reacting with amine groups in a curing agent to form a three-dimensional spatial network structure that is insoluble and infusible. Due to the excellent properties of epoxy resin, such as strong adhesion, small shrinkage, excellent dielectric performance, heat resistance, and good chemical stability, epoxy resin has been well developed in the field of adhesives. Epoxy resin-based structural adhesives are widely used in many industrial fields due to their good adhesion, chemical corrosion resistance, and mechanical properties.

[0003] However, with the increasing demand for material performance in modern industry, especially in the fields of aerospace and high-end automobile manufacturing, there is a higher expectation for the modulus of structural adhesives. Traditional epoxy resin-based structural adhesives are difficult to meet the strict requirements of high rigidity and deformation resistance after connecting some special structural parts.

[0004] Currently, in the prior art, in order to improve the modulus of epoxy resin-based structural adhesives, inorganic fillers are often added, but this often leads to a decrease in the toughness of the adhesive, and in actual application, due to uneven dispersion of the fillers, the modulus of the epoxy resin-based structural adhesive cannot be significantly and stably improved, and the bonding performance may also be affected.

[0005] Therefore, it is of great practical significance to develop an epoxy resin-based structural adhesive material that can significantly improve the modulus of the epoxy resin-based structural adhesive while maintaining good overall performance. SUMMARY

[0006] Therefore, the present application provides a high modulus epoxy resin-based structural adhesive material and a preparation method thereof.

[0007] The technical solution of the present application is as follows: A high modulus epoxy resin-based structural adhesive material, according to weight parts, comprises the following raw materials: 40-60 parts of epoxy resin, 15-30 parts of curing agent, 5-15 parts of nano-enhanced filler, 3-8 parts of toughening agent, 2-4 parts of auxiliary agent, and 0.5-2 parts of accelerator; The nano-enhanced filler is surface-modified nano-silicon dioxide, surface-treated nano-calcium carbonate, and modified multi-walled carbon nanotubes with a mass ratio of 1-2:1:0.1-0.3; The toughening agent is a mass ratio of 1-3:1 of carboxyl-terminated nitrile rubber and ethylene-propylene-diene rubber.

[0008] The carboxyl groups in the carboxyl-terminated butyl nitrile rubber molecule can chemically react with the epoxy resin and the curing agent, introducing flexible segments into the crosslinked network, and the ethylene-propylene-diene rubber as an elastomer can absorb energy and prevent cracks, and the combination of the two can improve the toughness of the structural adhesive while improving the modulus of the structural adhesive, so as to have good impact resistance, avoid the problem of increased brittleness due to the increase of modulus, and broaden the application range of the structural adhesive.

[0009] Further, the epoxy resin is a high-functionality bisphenol F type epoxy resin and an alicyclic epoxy resin with a mass ratio of 2-4:1, and the high functionality is 2.2.

[0010] The bisphenol F type epoxy resin has high reactivity and good process performance, and the alicyclic epoxy resin provides higher heat resistance and rigidity, and the combination of the two can ensure the smooth progress of the curing reaction and provide a good initial modulus basis for the structural adhesive.

[0011] Further, the curing agent is an aromatic amine curing agent and an acid anhydride curing agent with a mass ratio of 3-5:2.

[0012] The aromatic amine curing agent can quickly cure the epoxy resin to form a rigid structure and improve the modulus; after the acid anhydride curing agent participates in the reaction, the crosslinked network structure can be optimized, the cohesion of the system can be enhanced, the modulus can be further improved, and the heat resistance can be improved.

[0013] Further, the surface-modified nano-silicon dioxide is obtained by modifying the nano-silicon dioxide with an average particle size of 10-20 nm with silane coupling agent KH-560, and the amount of silane coupling agent KH-560 is 1%-3% of the mass of nano-silicon dioxide.

[0014] Further, the surface-treated nano-calcium carbonate is obtained by surface-treating the nano-calcium carbonate with an average particle size of 80-100 nm with aluminate coupling agent, and the amount of aluminate coupling agent is 1%-3% of the mass of nano-calcium carbonate.

[0015] Further, the modified multi-walled carbon nanotube is obtained by first treating the multi-walled carbon nanotube with an acid solution, and then aminoizing it with (3-aminopropyl) triethoxysilane, and the amount of (3-aminopropyl) triethoxysilane is 1%-3% of the mass of multi-walled carbon nanotube.

[0016] The nano calcium carbonate treated by aluminate coupling agent has enhanced lipophilicity on the surface, improved compatibility with the epoxy resin, can be uniformly dispersed in the system, effectively fills the resin matrix, and enhances the modulus of the structural adhesive; the nano silicon dioxide modified by silane coupling agent KH-560 can reduce the surface energy, avoid agglomeration, and further improve the modulus of the structural adhesive through physical enhancement; the multi-walled carbon nanotube has extremely high length-diameter ratio, the amino-modified multi-walled carbon nanotube has low density, improves the compatibility in the resin matrix, avoids agglomeration, and can form an effective stress transfer network in the resin matrix, significantly improves the modulus and strength of the material, and the synergistic effect of the three can significantly improve the overall modulus of the structural adhesive.

[0017] Further, the adjuvant is polyether modified polysilane, polybutylene succinate and polylactic acid with a mass ratio of 0.2-0.8:1-2:1.

[0018] The adjuvant of the present application is compounded by polyether modified polysilane, polybutylene succinate and polylactic acid, which has excellent wetting, dispersing and flowing properties, and the three compounds can make the nano reinforced filler better dispersed in the epoxy resin matrix, reduce agglomeration, significantly improve the modulus, and will not affect the adhesion, in addition, it can also adjust the crystallization behavior during curing.

[0019] Further, the accelerator is 2-methylimidazole.

[0020] 2-methylimidazole can effectively accelerate the reaction of epoxy resin and curing agent, reduce the curing temperature, shorten the curing time, and at the same time, will not affect the final modulus and other properties of the structural adhesive.

[0021] The present application also provides a preparation method of high modulus epoxy resin based structural adhesive material, and the specific preparation steps include: (1) adding nano reinforced filler into epoxy resin, stirring to obtain premix A; (2) adding toughening agent into premix A, continuing to stir to obtain premix B; (3) mixing curing agent and accelerator uniformly to obtain curing agent mixture C; (4) slowly adding curing agent mixture C into premix B, stirring uniformly to obtain target high modulus epoxy resin based structural adhesive material.

[0022] Further, in step (1), the stirring is carried out at 1500-2000 rpm for 30-40 min; In step (2), the time for continuing to stir is 15-20 min.

[0023] Compared with the prior art, the present application has the following advantages: 1. The epoxy resin-based structural adhesive material of the present application optimally selects raw materials and innovatively improves the process, the preparation method is simple and easy to implement, the components can be uniformly dispersed, no harmful substances are generated during the preparation process, the prepared structural adhesive has excellent bonding performance and realizes high modulus characteristics, and the tensile modulus of the prepared structural adhesive is 8.3-9.6 GPa and the bending modulus is 10.6-11.9 GPa, which can meet the demand of high-strength and high-modulus structural adhesive in high-end fields such as aerospace and automobile manufacturing, and has good application prospect.

[0024] 2. The epoxy resin of the present application is compounded with high-functionality bisphenol F type epoxy resin and alicyclic epoxy resin. The bisphenol F type epoxy resin has high reactivity and good process performance; the alicyclic epoxy resin gives higher heat resistance and rigidity, and the two are compounded to provide a good initial modulus basis for the structural adhesive on the basis of ensuring smooth curing reaction.

[0025] 3. The curing agent of the present application is compounded with aromatic amine curing agent and acid anhydride curing agent. The aromatic amine curing agent can make the epoxy resin quickly cure to form a rigid structure and improve the modulus; after the acid anhydride curing agent participates in the reaction, the crosslinking network structure can be optimized, the cohesion of the system is enhanced, the modulus is further improved, and the heat resistance is improved.

[0026] 4. The nano-enhanced filler of the present application is compounded with surface-modified nano-calcium carbonate, nano-silicon dioxide and multi-walled carbon nanotubes. The nano-calcium carbonate is treated with an aluminate coupling agent, the surface of the treated nano-calcium carbonate has enhanced lipophilicity and improved compatibility with the epoxy resin, can be uniformly dispersed in the system, effectively fills the resin matrix, and enhances the modulus of the structural adhesive; the nano-silicon dioxide modified by silane coupling agent KH-560 can reduce the surface energy and avoid agglomeration, and further improve the modulus of the structural adhesive through physical enhancement; the multi-walled carbon nanotube has a very high aspect ratio, the amino-modified multi-walled carbon nanotube has a low density, improves the compatibility in the resin matrix, avoids agglomeration, and can form an effective stress transfer network in the resin matrix, significantly improving the modulus and strength of the material, and the synergistic effect of the three significantly improves the overall modulus of the structural adhesive and the overall rigidity of the material.

[0027] 5. The toughening agent of the present application is compounded with carboxyl-terminated butyl nitrile rubber and ternary ethylene-propylene rubber, the carboxyl groups in the carboxyl-terminated butyl nitrile rubber molecule can react with the epoxy resin and the curing agent to introduce flexible segments into the crosslinking network, and the ternary ethylene-propylene rubber as an elastomer can absorb energy and prevent cracks, and the two can be compounded to improve the toughness of the structural adhesive while improving the modulus of the structural adhesive, so that the structural adhesive has good impact resistance, avoids the problem of increased brittleness caused by increased modulus, and widens the application range of the structural adhesive.

[0028] 6. The adjuvant of the present application is selected from polyether modified polysilicane, polybutylene succinate and polylactic acid, which have excellent wetting, dispersing and flowing properties, and the combination of the three can make the nano-enhanced filler better dispersed in the epoxy resin matrix, reduce agglomeration, stabilize the modulus and significantly improve it, and will not affect the adhesion; in addition, it can also adjust the crystallization behavior during curing.

[0029] 7. The accelerator 2-methylimidazole of the present application can effectively accelerate the reaction of epoxy resin and curing agent, reduce the curing temperature, shorten the curing time, and at the same time will not affect the final modulus and other properties of the structural adhesive. DETAILED DESCRIPTION

[0030] In order to better understand the technical content of the present application, the following specific examples are provided to further illustrate the present application.

[0031] The experimental methods used in the embodiments of the present application are all conventional methods unless otherwise specified.

[0032] The materials, reagents, etc. used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0033] The surface modified nano-silica of the present application is obtained by modifying the nano-silica with an average particle size of 20 nm with silane coupling agent KH-560, and the amount of silane coupling agent KH-560 is 2% of the mass of nano-silica, specifically: the nano-silica and the silane coupling agent KH-560 are mixed in a high-speed mixer at a speed of 1000 rpm for 10 min for modification treatment.

[0034] The surface treated nano-calcium carbonate of the present application is obtained by surface treating nano-calcium carbonate with an average particle size of 80 nm with aluminate coupling agent, and the amount of aluminate coupling agent is 2% of the mass of nano-calcium carbonate; specifically: the nano-calcium carbonate and the aluminate coupling agent are mixed in a high-speed mixer at a speed of 1200 rpm for 15 min for surface treatment.

[0035] The modified multi-walled carbon nanotube of the present application is obtained by first treating the multi-walled carbon nanotube with an acid solution, and then aminoating it with (3-aminopropyl) triethoxysilane, and the amount of (3-aminopropyl) triethoxysilane is 2% of the mass of the multi-walled carbon nanotube; specifically: according to the solid-liquid ratio of 1:3-5 mg / mL, the multi-walled carbon nanotube is placed in a 1 mol / L nitric acid solution and stirred for 2 h, filtered, washed and dried, the product is placed in 200 mL of anhydrous ethanol, (3-aminopropyl) triethoxysilane is added, and ultrasonic treatment is carried out at 20 kHz and 50℃ for 6 h, and then filtered, washed and dried.

[0036] Example 1 The high modulus epoxy resin based structural adhesive material of the embodiment is prepared by taking 50 parts of epoxy resin (mass ratio 2:1 of high functionality 2.2 bisphenol F type epoxy resin and alicyclic epoxy resin), 20 parts of curing agent (mass ratio 3:2 of aromatic amine curing agent and acid anhydride curing agent), 10 parts of nano-enhanced filler (mass ratio 1:1:0.2 of surface modified nano-silicon dioxide, surface treated nano-calcium carbonate and modified multi-walled carbon nanotube), 5 parts of toughening agent (mass ratio 2:1 of carboxyl-terminated butyl nitrile rubber and ternary ethylene propylene rubber), 3 parts of auxiliary agent (mass ratio 0.5:2:1 of polyether modified polysilane, polybutylene succinate and polylactic acid) and 1 part of 2-methyl imidazole.

[0037] The preparation method of the high modulus epoxy resin based structural adhesive material is as follows: (1) The nano-enhanced filler is added to the epoxy resin, stirred at 1800 rpm for 35 min to obtain premix A; (2) The toughening agent is added to the premix A, and stirring is continued for 18 min to obtain premix B; (3) The curing agent and the accelerator are mixed uniformly to obtain a curing agent mixture C; (4) The curing agent mixture C is slowly added to the premix B, and stirred uniformly to obtain the target high modulus epoxy resin based structural adhesive material.

[0038] Example 2 The high modulus epoxy resin based structural adhesive material of the embodiment is prepared by taking 40 parts of epoxy resin (mass ratio 2:1 of high functionality 2.2 bisphenol F type epoxy resin and alicyclic epoxy resin), 15 parts of curing agent (mass ratio 3:2 of aromatic amine curing agent and acid anhydride curing agent), 5 parts of nano-enhanced filler (mass ratio 1:1:0.2 of surface modified nano-silicon dioxide, surface treated nano-calcium carbonate and modified multi-walled carbon nanotube), 3 parts of toughening agent (mass ratio 2:1 of carboxyl-terminated butyl nitrile rubber and ternary ethylene propylene rubber), 2 parts of auxiliary agent (mass ratio 0.5:2:1 of polyether modified polysilane, polybutylene succinate and polylactic acid) and 0.5 parts of 2-methyl imidazole.

[0039] The preparation method of the high modulus epoxy resin based structural adhesive material is as follows: (1) The nano-enhanced filler is added to the epoxy resin, stirred at 1500 rpm for 30 min to obtain premix A; (2) The toughening agent is added to the premix A, and stirring is continued for 15 min to obtain premix B; (3) The curing agent and the accelerator are mixed uniformly to obtain a curing agent mixture C; (4) slowly add the curing agent mixture C into the premix B, stir evenly, get the target high modulus epoxy resin based structural adhesive material.

[0040] Example 3 The high modulus epoxy resin based structural adhesive material of the present example, according to parts by weight, take 60 parts of epoxy resin (mass ratio 2:1 of high functionality 2.2 of bisphenol F type epoxy resin and alicyclic epoxy resin), 30 parts of curing agent (mass ratio 3:2 of aromatic amine curing agent and acid anhydride curing agent), 15 parts of nano enhanced filler (mass ratio 1:1:0.2 of surface modified nano silicon dioxide, surface treated nano calcium carbonate and modified multi-walled carbon nanotube), 8 parts of toughening agent (mass ratio 2:1 of carboxyl-terminated butyl nitrile rubber and ternary ethylene propylene rubber), 4 parts of auxiliary agent (mass ratio 0.5:2:1 of polyether modified polysilane, polybutylene succinate and polylactic acid) and 2 parts of 2-methyl imidazole.

[0041] The preparation method of the above high modulus epoxy resin based structural adhesive material, the specific preparation steps include: (1) add the nano enhanced filler into the epoxy resin, stir at 2000 rpm for 40 min, get the premix A; (2) add the toughening agent into the premix A, continue to stir for 20 min, get the premix B; (3) mix the curing agent and the accelerator evenly, get the curing agent mixture C; (4) slowly add the curing agent mixture C into the premix B, stir evenly, get the target high modulus epoxy resin based structural adhesive material.

[0042] Comparative Example 1 The difference from Example 1 is that the nano enhanced filler is composed of nano silicon dioxide, nano calcium carbonate and multi-walled carbon nanotube with mass ratio 1:1:0.8, i.e. without surface modification, and other consistent with Example 1.

[0043] Comparative Example 2 The difference from Example 1 is that the epoxy resin is bisphenol F type epoxy resin and bisphenol A type epoxy resin with mass ratio 2:1, and other consistent with Example 1.

[0044] Comparative Example 3 The difference from Example 1 is that the toughening agent is carboxyl-terminated butyl nitrile rubber, and other consistent with Example 1.

[0045] Comparative Example 4 The difference from Example 1 is that the curing agent is aromatic amine curing agent, and other consistent with Example 1.

[0046] Comparative Example 5 The difference from Example 1 is that no auxiliary agent is added, and other consistent with Example 1.

[0047] Test example The structural glue prepared in Examples 1-3 and Comparative Examples 1-5 was subjected to performance testing, and the test indexes included modulus testing, bonding strength testing and impact toughness testing.

[0048] Modulus testing: an electronic universal material testing machine was used to test the tensile modulus and bending modulus according to the GB / T 2567-2021 standard; Bonding strength testing: bonding strength testing was performed on aluminum alloy test pieces according to the GB / T 7124-2008 standard; Impact toughness testing: an impact toughness test was performed on a cantilever beam impact testing machine according to the GB / T 1843-2008 standard.

[0049] The results are shown in Table 1.

[0050] Table 1

[0051] As can be seen from Table 1, the structural glue prepared in the examples has high modulus characteristics, and simultaneously performs excellently in terms of bonding strength and impact toughness, etc., and can meet the demand for high-strength and high-modulus structural adhesive in high-end fields such as aerospace and automobile manufacturing, and has a good application prospect.

[0052] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-modulus epoxy resin-based structural adhesive material, characterized in that, By weight, it includes the following raw materials: 40-60 parts epoxy resin, 15-30 parts curing agent, 5-15 parts nano-reinforcing filler, 3-8 parts toughening agent, 2-4 parts additives and 0.5-2 parts accelerator. The nano-reinforcing filler is surface-modified nano-silica with a mass ratio of 1-2:1:0.1-0.3, surface-treated nano-calcium carbonate, and modified multi-walled carbon nanotubes. The toughening agent is a combination of carboxyl-terminated butadiene-acrylonitrile rubber and ethylene propylene diene monomer (EPDM) rubber in a mass ratio of 1-3:

1.

2. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The epoxy resin is a high-functionality bisphenol F type epoxy resin and an alicyclic epoxy resin with a mass ratio of 2-4:1, and the high functionality is 2.

2.

3. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The curing agent is an aromatic amine curing agent and an acid anhydride curing agent with a mass ratio of 3-5:

2.

4. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The surface-modified nano-silica is obtained by modifying nano-silica with an average particle size of 10-20 nm with silane coupling agent KH-560. The amount of silane coupling agent KH-560 is 1%-3% of the mass of nano-silica.

5. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The surface-treated nano-calcium carbonate is obtained by surface treatment of nano-calcium carbonate with an average particle size of 80-100nm using an aluminate coupling agent, with the amount of aluminate coupling agent being 1%-3% of the mass of the nano-calcium carbonate.

6. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The modified multi-walled carbon nanotubes are obtained by first treating the multi-walled carbon nanotubes with an acid solution, and then amidizing them with (3-aminopropyl)triethoxysilane. The amount of (3-aminopropyl)triethoxysilane used is 1%-3% of the mass of the multi-walled carbon nanotubes.

7. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The additives are polyether-modified polysiloxane, polybutylene succinate and polylactic acid in a mass ratio of 0.2-0.8:1-2:

1.

8. The high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The promoter is 2-methylimidazole.

9. The method for preparing a high-modulus epoxy resin-based structural adhesive material as described in claim 1, characterized in that, The specific preparation steps include: (1) Add nano-reinforced filler to epoxy resin and stir to obtain premix A; (2) Add the toughening agent to premix A and continue stirring to obtain premix B; (3) Mix the curing agent and accelerator evenly to obtain curing agent mixture C; (4) Slowly add curing agent mixture C to premixed material B and stir evenly to obtain the target high modulus epoxy resin-based structural adhesive material.

10. The method for preparing a high-modulus epoxy resin-based structural adhesive material as described in claim 9, characterized in that, In step (1), the stirring is carried out at 1500-2000 rpm for 30-40 min; In step (2), the stirring time is 15-20 minutes.

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