Flexible chain modified epoxy resin, single-component epoxy structural adhesive and preparation method of flexible chain modified epoxy resin

Abstract

The invention relates to flexible chain modified epoxy resin, a single-component epoxy structural adhesive and a preparation method of the flexible chain modified epoxy resin and the single-component epoxy structural adhesive. The modified epoxy resin is obtained by reaction of bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil, has low modulus and good adhesion, and can endow an adhesive system with good flexibility. The flexible chain modified epoxy resin, the liquid nitrile rubber modified epoxy resin and the core-shell nanoparticle toughening agent are compounded to achieve synergistic toughening, and then a proper curing agent, a proper accelerant and a proper thixotropic agent are used in a matched mode to prepare the single-component epoxy structural adhesive. According to the present invention, the thermal stress existing between the single-component epoxy structural adhesive and the base material during the heat treatment process can be effectively solved so as to provide the good multi-base material adhesion ability, the high mechanical property at the normal temperature can be ensured, the low temperature flexibility is improved, the high and low temperature performance is enhanced, and the adhesion failure caused by the brittle fracture is avoided.

Description

Technical Field

[0001] This invention belongs to the field of sealant technology, and relates to epoxy sealants, specifically to flexible chain modified epoxy resins, one-component epoxy structural adhesives, and their preparation methods. Background Technology

[0002] With the rapid development of materials science and high-tech manufacturing, material joining technologies are constantly moving towards lightweighting, high performance, and environmental friendliness. Adhesive bonding, as a highly efficient and low-energy-consumption joining method, is receiving increasing attention. Epoxy structural adhesives, with their excellent mechanical strength, chemical resistance, and electrical insulation, are widely used in structural bonding in aerospace, automotive manufacturing, electronic equipment, and motors.

[0003] Traditional epoxy structural adhesives are mostly two-component systems, which are complex to operate and have long curing times, making it difficult to meet the rapid curing requirements of industrial production. Single-component thermosetting epoxy structural adhesives, on the other hand, have significant advantages: they are easy to operate and can be cured rapidly by heating, greatly improving production efficiency. In practical applications, epoxy structural adhesives need to bond various substrates, such as metals, plastics, ceramics, and composite materials. The differences in surface properties of different substrates make bonding dissimilar materials difficult. Furthermore, because single-component epoxy structural adhesives achieve bonding through thermosetting, their bond strength needs to be improved.

[0004] Therefore, developing a single-component thermosetting epoxy structural adhesive with multi-substrate bonding capability, good bonding strength, high mechanical strength, and good thermal stability is of great practical significance for meeting the bonding requirements in complex industrial environments. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a one-component epoxy structural adhesive with multi-substrate bonding capability, wherein the one-component epoxy structural adhesive also has good bonding strength, high mechanical strength and high and low temperature performance.

[0006] The first aspect of the present invention is to provide a modified epoxy resin (flexible chain modified epoxy resin) obtained by reacting bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil in the presence of a catalyst.

[0007] In some embodiments, the epoxidized soybean oil has an epoxy value of 6.0% to 7.0% and an iodine value of ≤ 6.0 gI2 / 100g.

[0008] In some embodiments, the bisphenol A diglycidyl ether is selected from at least one of E-51, E-44, and E-20.

[0009] In some embodiments, the catalyst is a quaternary ammonium salt catalyst.

[0010] In some embodiments, the catalyst is tetrabutylammonium bromide.

[0011] In some embodiments, the mass ratio of bisphenol A diglycidyl ether, butenedioic acid, and epoxidized soybean oil is (2.7~3.3): (0.9~1.1): (0.9~1.1).

[0012] In some embodiments, the mass fraction of the catalyst is 0.3% to 0.7% of the total mass of bisphenol A diglycidyl ether, butenedioic acid, and epoxidized soybean oil.

[0013] A second aspect of the present invention is to provide a method for preparing the modified epoxy resin as described above, comprising the following steps:

[0014] (1) Stir the bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil evenly, heat to 95℃~105℃, add the catalyst, and heat to 115℃~125℃ to carry out the reaction;

[0015] (2) Measure the acid value of the reactants until the acid value is <2.0 mgKOH / g to obtain the modified epoxy resin.

[0016] A third aspect of the present invention is to provide a one-component epoxy structural adhesive, prepared by means of raw materials comprising the following components in parts by weight:

[0017] 20-35 parts of bisphenol A diglycidyl ether

[0018] 10-20 parts of liquid nitrile rubber modified epoxy resin

[0019] 10-20 parts of the modified epoxy resin as described above

[0020] 5-20 parts of core-shell nanoparticle toughening agent

[0021] 10-30 parts of inorganic filler

[0022] 5-10 parts of latent curing agent

[0023] Accelerator 0.5-2 parts

[0024] 3-5 parts of thixotropic agent

[0025] 3-5 parts diluent.

[0026] In some embodiments, the one-component epoxy structural adhesive is prepared from raw materials comprising the following components, in parts by weight:

[0027] 20-30 parts of bisphenol A diglycidyl ether

[0028] 10-15 parts of liquid nitrile rubber modified epoxy resin

[0029] 10-20 parts of the modified epoxy resin as described above

[0030] 10-20 parts of core-shell nanoparticle toughening agent

[0031] 15-25 parts of inorganic filler

[0032] 6-9 parts of latent curing agent

[0033] 1-2 parts of accelerator

[0034] 3-5 parts of thixotropic agent

[0035] 3-5 parts diluent.

[0036] In some embodiments, the bisphenol A diglycidyl ether is selected from at least one of E-51, E-44, and E-20.

[0037] In some embodiments, the liquid nitrile rubber modified epoxy resin is selected from at least one of carboxyl-terminated liquid nitrile rubber modified epoxy resin, amine-terminated liquid nitrile rubber modified epoxy resin, hydroxyl-terminated liquid nitrile rubber modified epoxy resin, and epoxy-terminated liquid nitrile rubber modified epoxy resin.

[0038] In some embodiments, the core-shell nanoparticle toughening agent is selected from at least one of silicone rubber core-shell nanoparticle toughening agents, styrene-butadiene rubber core-shell nanoparticle toughening agents, and polybutadiene rubber core-shell nanoparticle toughening agents.

[0039] In some embodiments, the inorganic filler is selected from at least one of nano-calcium carbonate, heavy calcium carbonate, silica powder, mica powder, alumina, aluminum hydroxide, and talc.

[0040] In some embodiments, the latent curing agent is selected from at least one of dicyandiamide and hydrazide.

[0041] In some embodiments, the promoter is selected from at least one of substituted urea, imidazole, imidazole derivatives, and aromatic amines.

[0042] In some embodiments, the thixotropic agent is selected from at least one of hydrophilic fumed silica, hydrophobic fumed silica, bentonite, polyamide wax, and hydrogenated castor oil.

[0043] In some embodiments, the diluent is selected from at least one of monofunctional reactive diluents, difunctional reactive diluents, and trifunctional reactive diluents.

[0044] A fourth aspect of the present invention is to provide a method for preparing the single-component epoxy structural adhesive as described above, comprising the following steps:

[0045] (1) The bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, modified epoxy resin and core-shell nanoparticle toughening agent are added to a planetary mixer and stirred at 800 r / min-1200 r / min and vacuum degree -0.095 MPa~ -0.1 MPa;

[0046] (2) Add the inorganic filler, latent curing agent, accelerator and thixotropic agent to the planetary machine, stir and mix at 800 r / min-1200 r / min, and then stir and mix at 800 r / min-1200 r / min and vacuum degree -0.095 MPa ~ -0.1 MPa;

[0047] (3) Add the diluent to the planetary machine and stir and mix at 800r / min-1200r / min and vacuum degree of -0.095MPa ~ -0.1MPa to obtain the single-component epoxy structural adhesive.

[0048] This invention prepares a flexible chain modified epoxy resin by reacting bisphenol A diglycidyl ether with butenedioic acid and epoxidized soybean oil. The flexible chain modified epoxy resin has a low modulus and good adhesion, which can give the adhesive system good flexibility and ensure that the adhesive will not debond or crack when bonding different materials, so that the adhesive has good multi-substrate adhesion ability.

[0049] The flexible chain modified epoxy resin, liquid nitrile rubber modified epoxy resin, and core-shell nanoparticle toughening agent of this invention are compounded to achieve synergistic toughening of the three. Then, a single-component epoxy structural adhesive is prepared by combining it with a suitable curing agent, accelerator and thixotropic agent. This not only effectively solves the thermal stress between the adhesive and the substrate during heat treatment and has good multi-substrate adhesion ability, but also ensures high mechanical properties at room temperature, while improving low-temperature flexibility and high and low temperature stability, avoiding adhesive failure caused by brittle fracture.

[0050] The single-component epoxy structural adhesive of this invention uses environmentally friendly raw materials and green production processes in its preparation, which reduces the impact on the environment, meets the requirements of sustainable development, and the raw materials are simple, readily available, and easy to operate. Attached Figure Description

[0051] Figure 1 This is the FT-IR spectrum of the flexible chain modified epoxy resin of this invention. Detailed Implementation

[0052] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0053] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.

[0054] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0055] Some embodiments of the present invention relate to a modified epoxy resin obtained by reacting bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil in the presence of a catalyst.

[0056] In some embodiments, the epoxidized soybean oil has an epoxy value of 6.0% to 7.0% and an iodine value of ≤ 6.0 gI2 / 100g.

[0057] In some embodiments, the bisphenol A diglycidyl ether is selected from at least one of E-51, E-44 and E-20; preferably E-51.

[0058] In some embodiments, the mass ratio of bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil is (2.7~3.3): (0.9~1.1): (0.9~1.1), preferably (2.9~3.1): (0.9~1): (0.9~1).

[0059] In some embodiments, the mass fraction of the catalyst relative to the total mass of bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil is 0.3% to 0.7%, preferably 0.4% to 0.6%.

[0060] This invention prepares a flexible chain modified epoxy resin by reacting bisphenol A diglycidyl ether with butenedioic acid and epoxidized soybean oil. The flexible chain modified epoxy resin has a low modulus and good adhesion, giving the polymer system good flexibility and ensuring that the adhesive will not debond or crack when bonding different materials. The adhesive has good multi-substrate adhesion ability.

[0061] Some embodiments of the present invention relate to a method for preparing the modified epoxy resin as described above, comprising the following steps:

[0062] (1) Stir the bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil evenly, heat to 95℃~105℃, add the catalyst, and heat to 115℃~125℃ to carry out the reaction;

[0063] (2) Measure the acid value of the reactants until the acid value is <2.0 mgKOH / g to obtain the modified epoxy resin.

[0064] In some embodiments, in step (1), bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil are stirred evenly, heated to 100°C~105°C, tetrabutylammonium bromide is added, and the temperature is raised to 120°C~125°C for reaction.

[0065] Some embodiments of the present invention relate to a one-component epoxy structural adhesive, prepared by means of raw materials comprising the following components in parts by weight:

[0066] 20-35 parts of bisphenol A diglycidyl ether

[0067] 10-20 parts of liquid nitrile rubber modified epoxy resin

[0068] 10-20 parts of the modified epoxy resin as described above

[0069] 5-20 parts of core-shell nanoparticle toughening agent

[0070] 10-30 parts of inorganic filler

[0071] 5-10 parts of latent curing agent

[0072] Accelerator 0.5-2 parts

[0073] 3-5 parts of thixotropic agent

[0074] 3-5 parts diluent.

[0075] In some embodiments, the one-component epoxy structural adhesive is prepared from raw materials comprising the following components, in parts by weight:

[0076] 20-30 parts of bisphenol A diglycidyl ether

[0077] 10-15 parts of liquid nitrile rubber modified epoxy resin

[0078] 10-20 parts of the modified epoxy resin as described above

[0079] 10-20 parts of core-shell nanoparticle toughening agent

[0080] 15-25 parts of inorganic filler

[0081] 6-9 parts of latent curing agent

[0082] 1-2 parts of accelerator

[0083] 3-5 parts of thixotropic agent

[0084] 3-5 parts diluent.

[0085] In some embodiments, the one-component epoxy structural adhesive is prepared from raw materials comprising the following components, in parts by weight:

[0086] 20-25 parts of bisphenol A diglycidyl ether

[0087] 10-15 parts of liquid nitrile rubber modified epoxy resin

[0088] 10-19 parts of the modified epoxy resin as described above

[0089] 11-16 parts of core-shell nanoparticle toughening agent

[0090] 20-25 parts of inorganic filler

[0091] 7-9 parts of latent curing agent

[0092] 1-2 parts of accelerator

[0093] 4-5 parts of thixotropic agent

[0094] Diluent 3.5-4.5 parts.

[0095] In some embodiments, the bisphenol A diglycidyl ether is selected from at least one of E-51, E-44, and E-20.

[0096] In some embodiments, the E-51 has an epoxy value of 0.48~0.54 eq / 100g, a viscosity of 1100~1400 mPa.s at 25°C, a purity of ≥99%, an epoxy equivalent of 185~195 g / eq, and is manufactured by Nanjing Shuguang Chemical Group, with the product number S-001.

[0097] In some embodiments, the E-44 has an epoxy value of 0.41~0.47 eq / 100g, a viscosity of 2500~4000 mPa.s at 25°C, a purity of ≥98%, an epoxy equivalent of 210~240 g / eq, and is manufactured by Baling Petrochemical Co., Ltd., with the product number E-44-01.

[0098] In some embodiments, the E-20 has an epoxy value of 0.18~0.22 eq / 100g, a viscosity of 10000~20000 mPa.s at 25°C, a purity of ≥98%, an epoxy equivalent of 450~550 g / eq, and is manufactured by Jiangsu Sanmu Group Co., Ltd., with the product number E-20-02.

[0099] In some embodiments, the liquid nitrile rubber modified epoxy resin is selected from at least one of carboxyl-terminated liquid nitrile rubber (CTBN) modified epoxy resin, amine-terminated liquid nitrile rubber (ATBN) modified epoxy resin, hydroxyl-terminated liquid nitrile rubber (HTBN) modified epoxy resin, and epoxy-terminated liquid nitrile rubber (ETBN) modified epoxy resin.

[0100] In some embodiments, the carboxyl-terminated liquid nitrile butadiene rubber (CTBN) has a carboxyl content of 0.08~0.12 eq / 100g, a viscosity of 8000~12000 mPa.s at 25°C, an acrylonitrile content of 27%~31% (mass fraction), and a purity of ≥98%.

[0101] In some embodiments, the terminal amine-terminated liquid nitrile butadiene rubber (ATBN) has an amine value of 0.07~0.11 eq / 100g, a viscosity of 10000~14000 mPa.s at 25°C, an acrylonitrile content of 26%~30%, and a purity of ≥97%.

[0102] In some embodiments, the hydroxyl-terminated liquid nitrile butadiene rubber (HTBN) has a hydroxyl value of 0.09~0.13 eq / 100g, a viscosity of 7000~11000 mPa.s at 25°C, an acrylonitrile content of 28%~32%, and a purity of ≥98%.

[0103] In some embodiments, the terminal epoxy-based liquid nitrile butadiene rubber (ETBN) has an epoxy value of 0.06~0.10 eq / 100g, a viscosity of 9000~13000 mPa.s at 25°C, an acrylonitrile content of 27%~31%, and a purity of ≥97%.

[0104] In some embodiments, the liquid nitrile rubber modified epoxy resin is a carboxyl-terminated liquid nitrile rubber (CTBN) modified epoxy resin. Due to its large molecular weight and fewer reactive functional groups, the carboxyl-terminated liquid nitrile rubber modified epoxy resin has insufficient wetting and adhesion capabilities at interfaces of low surface energy materials. Core-shell nanoparticles possess an easily dispersed hard outer shell and an elastomer core. When the system is subjected to external forces, they can absorb energy through deformation, cavitation, etc. Simultaneously, the fragmentation of nanoparticles can deflect and hinder the propagation of microcracks, preventing the formation of large cracks and achieving toughening. Combining them with the flexible chain modified epoxy resin of this invention can improve adhesion and synergistically toughen the adhesive. The use of a curing agent with a low curing temperature and a mild exothermic reaction, as well as a medium-temperature accelerator, enables rapid curing at lower temperatures. Furthermore, the use of a suitable thixotropic agent imparts good rheological properties to the adhesive without affecting the adhesive effect. Through the synergistic effect between the raw materials, the single-component epoxy structural adhesive of this invention possesses good multi-substrate adhesion capabilities, good shear strength, peel strength, and high and low temperature resistance.

[0105] In some embodiments, the core-shell nanoparticle toughening agent is selected from at least one of silicone rubber core-shell nanoparticle toughening agents, styrene-butadiene rubber (SBR) core-shell nanoparticle toughening agents, and polybutadiene rubber (PB) core-shell nanoparticle toughening agents.

[0106] In some embodiments, the core layer of the silicone rubber core-shell nanoparticles is polydimethylsiloxane (PDMS), the shell layer is methyl methacrylate-styrene copolymer (MMA-PS), the particle size is 80~150 nm, the solid content is 25%~35% (mass fraction, solvent is ethyl acetate), and the dispersibility is ≤0.2 (PDI value).

[0107] In some embodiments, the styrene-butadiene rubber (SBR) core-shell nanoparticles have a core layer of styrene-butadiene copolymer and a shell layer of polystyrene (PS), with a particle size of 100~200 nm, a solid content of 30%~40% (solvent is toluene), and a glass transition temperature (Tg) of -55~-45℃.

[0108] In some embodiments, the polybutadiene rubber (PB) core-shell nanoparticles have a polybutadiene core layer and a methyl methacrylate copolymer (PMMA) shell layer, with a particle size of 60~120 nm, a solid content of 28%~38% (xylene as solvent), and a Tg of -60~-50℃.

[0109] In some embodiments, the latent curing agent is selected from at least one of dicyandiamide and hydrazide-based curing agents.

[0110] In some embodiments, the acylhydrazide curing agent includes isophthalic acid hydrazide (IPH), adipate diacid hydrazide (ADH), and sebacic acid diacid hydrazide (SDH).

[0111] In some embodiments, the promoter is selected from at least one of substituted urea, imidazole, imidazole derivatives, and aromatic amines.

[0112] In some embodiments, the substituted urea is 3-phenyl-1,1-dimethylurea (DPU).

[0113] In some embodiments, the imidazole is 2-methylimidazole (2-MI).

[0114] In some embodiments, the imidazole derivative includes 2-ethyl-4-methylimidazolium (2E4MI), 1-cyanoethyl-2-ethyl-4-methylimidazolium (CE2E4MI), 2-phenylimidazolium (2-PI), and 2-ethyl-4-methylimidazolium (2E4MI).

[0115] In some embodiments, the aromatic amine is o-phenylenediamine.

[0116] In some embodiments, the thixotropic agent is selected from at least one of hydrophilic fumed silica, hydrophobic fumed silica, bentonite, polyamide wax, and hydrogenated castor oil.

[0117] In some embodiments, the hydrophilic fumed silica has a specific surface area of ​​150-200 m² / g, a particle size of 10-20 nm, and a water content of ≤2%.

[0118] In some embodiments, the hydrophobic fumed silica has a specific surface area of ​​120~180 m² / g, a particle size of 15~25 nm, and a hydrophobicity of ≥95%.

[0119] In some embodiments, the bentonite has a particle size of 1-5 μm, an activation degree of ≥90%, an expansion ratio of 8-12 times, and a moisture content of ≤10%.

[0120] In some embodiments, the polyamide wax has a melting point of 100-110°C, a particle size of 2-5 μm, and a thixotropic index of ≥3.0 (25°C, 6 rpm / 60 rpm).

[0121] In some embodiments, the hydrogenated castor oil has a melting point of 85-88°C, a particle size of 3-8 μm, an acid value of ≤5 mg KOH / g, and an iodine value of ≤5 gI2 / 100g.

[0122] In some embodiments, the diluent is selected from at least one of monofunctional reactive diluents, difunctional reactive diluents, and trifunctional reactive diluents.

[0123] In some embodiments, the monofunctional active diluent includes phenyl glycidyl ether (PGE) and benzyl glycidyl ether (BGE).

[0124] In some embodiments, the phenyl glycidyl ether (PGE) has an epoxy value of 0.52~0.58 eq / 100g, a viscosity of 15~25 mPa.s at 25°C, and a purity of ≥98%.

[0125] In some embodiments, the benzyl glycidyl ether (BGE) has an epoxy value of 0.45~0.51 eq / 100g, a viscosity of 20~30 mPa.s at 25°C, and a purity of ≥97%.

[0126] In some embodiments, the bifunctional active diluent includes 1,6-hexanediol diglycidyl ether (HDGE) and neopentyl glycol diglycidyl ether (NPGDGE).

[0127] In some embodiments, the 1,6-hexanediol diglycidyl ether (HDGE), model HD-100, is sourced from Nanjing Shuguang Chemical Group, with an epoxy value of 0.62~0.68 eq / 100g, a viscosity of 25~40 mPa.s at 25℃, and a purity ≥98%.

[0128] In some embodiments, the neopentyl glycol diglycidyl ether (NPGDGE), model NP-100, is sourced from Nanjing Shuguang Chemical Group, with an epoxy value of 0.65~0.71 eq / 100g, a viscosity of 30~45 mPa.s at 25℃, and a purity ≥97%.

[0129] In some embodiments, the trifunctional active diluent includes trimethylolpropane triglycidyl ether (TMPGE) and glyceryl triglycidyl ether (GTGE).

[0130] In some embodiments, the trimethylolpropane triglycidyl ether (TMPGE) has an epoxy value of 0.72~0.78 eq / 100g, a viscosity of 90~110 mPa.s at 25°C, and a purity of ≥98%.

[0131] In some embodiments, the glycerol triglycidyl ether (GTGE) has an epoxy value of 0.75~0.81 eq / 100g, a viscosity of 100~130 mPa.s at 25°C, and a purity of ≥97%.

[0132] Some embodiments of the present invention relate to a method for preparing the single-component epoxy structural adhesive as described above, comprising the following steps:

[0133] (1) The bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, modified epoxy resin and core-shell nanoparticle toughening agent are added to a planetary mixer and stirred at 800 r / min-1200 r / min and vacuum degree -0.095 MPa~ -0.1 MPa;

[0134] (2) Add the inorganic filler, latent curing agent, accelerator and thixotropic agent to the planetary machine, stir and mix at 800 r / min-1200 r / min, and then stir and mix at 800 r / min-1200 r / min and vacuum degree -0.095 MPa ~ -0.1 MPa;

[0135] (3) Add the diluent to the planetary machine and stir and mix at 800r / min-1200r / min and vacuum degree of -0.095MPa ~ -0.1MPa to obtain the single-component epoxy structural adhesive.

[0136] In some embodiments, the preparation method includes the following steps:

[0137] (1) The bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, modified epoxy resin and core-shell nanoparticle toughening agent are added to a planetary mixer and stirred for 15 min to 30 min at 800 r / min-1200 r / min and vacuum degree of -0.095 MPa to -0.1 MPa.

[0138] (2) Add the inorganic filler, latent curing agent, accelerator and thixotropic agent, stir at 800r / min-1200r / min for 5min-15min, and then stir and mix at 800r / min-1200r / min and vacuum degree -0.095MPa ~ -0.1 MPa for 15min-30min;

[0139] (3) Add the diluent and stir at 800r / min-1200r / min and vacuum degree -0.095MPa ~ -0.1MPa for 15min-30min to obtain the single-component epoxy structural adhesive.

[0140] In some embodiments, the preparation method includes the following steps:

[0141] (1) The bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, modified epoxy resin and core-shell nanoparticle toughening agent are added to a planetary mixer and stirred for 15 min to 25 min at 900 r / min-1100 r / min and vacuum degree of -0.095 MPa to -0.1 MPa.

[0142] (2) Add the inorganic filler, latent curing agent, accelerator and thixotropic agent, stir at 800r / min-900r / min for 8min-12min, and then stir at 900r / min-1100r / min and vacuum degree -0.095MPa ~ -0.1 MPa for 20min-30min;

[0143] (3) Add the diluent and stir at 900r / min-1100r / min and vacuum degree -0.095MPa ~ -0.1MPa for 20min-35min to obtain the single-component epoxy structural adhesive.

[0144] The present invention will be further described in detail below with reference to specific embodiments.

[0145] Some of the reagents used in this invention are from the following sources:

[0146] Bisphenol A diglycidyl ether E-51: Manufacturer is Nanjing Shuguang Chemical Group, product number S-001;

[0147] Epoxidized soybean oil: The manufacturer is Shandong Rongshengyuan Chemical Co., Ltd.

[0148] Carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin: model CTBN-1300×10, manufacturer is Changzhou Jien Chemical Co., Ltd.

[0149] Polybutadiene rubber core-shell nanoparticle toughening agent: model number NBR-300, manufacturer is Suzhou Saifei Chemical Co., Ltd.;

[0150] Inorganic filler silica powder: Model number HY-G5, manufactured by Shenzhen Haiyang Powder Technology Co., Ltd.

[0151] Latent curing agent, amide hydrazide, isophthalic acid hydrazide: model IPH-99, source: Shanghai Maclean Biochemical Technology Co., Ltd.;

[0152] Accelerator 2-ethyl-4-methylimidazole (2E4MI): Model EMI-24, source: Nanjing Ruize Chemical Co., Ltd.

[0153] Thixotropic bentonite: Model BT-300, source: Zhejiang Fenghong New Material Co., Ltd.;

[0154] Diluent: Phenyl glycidyl ether (PGE): Model PG-100, source: Nanjing Shuguang Chemical Group;

[0155] Polyurethane modified epoxy resin: model EPU-133, sourced from Huntsman Group;

[0156] Organosilicon-modified epoxy resin: Model ES 6862, sourced from Huntsman Group;

[0157] Polyurethane modified epoxy resin: Model QR-9466, source: Aidi Chemicals;

[0158] Hyperbranched polymer toughening agent T054: Shenzhen Huiya New Material Technology Co., Ltd.

[0159] The following examples illustrate the preparation of flexible chain modified epoxy resins.

[0160] Preparation method:

[0161] (1) Bisphenol A diglycidyl ether E-51, butenedioic acid, and epoxidized soybean oil were added to the reactor at a mass ratio of 3:1:1. The mixture was mechanically stirred for 30 min, and after evacuation, nitrogen gas was introduced. This process was repeated 3 times to replace the air. The temperature was raised to 100℃, and 0.5% of the total mass fraction of the reactants in tetrabutylammonium bromide was dissolved in 10 mL of ethanol and added to the reactor. The temperature was then raised to 120℃ for reaction.

[0162] (2) Measure the acid value every 1 h until the acid value is <2.0 mgKOH / g, evacuate for 60 min to remove volatile substances, and cool down to obtain the flexible chain modified epoxy resin for subsequent experiments.

[0163] Figure 1 The FT-IR spectrum of the prepared flexible chain modified epoxy resin is shown in the figure. As can be seen from the figure, the flexible chain modified epoxy resin exhibits a high FT-IR spectrum at 1709 cm⁻¹. -1 There is a characteristic peak of ester group at 910 cm⁻¹. -1 An epoxide absorption peak appeared at 1200 cm⁻¹, and also at 1200 cm⁻¹. -1 The secondary alcohol absorption peak appearing at the point indicates that the carboxylic acid participated in the epoxide ring-opening process, generating the target product.

[0164] In the following examples, the experimental environment temperature was 25 ℃ and the relative humidity was 50% RH.

[0165] Example 1

[0166] This embodiment provides a one-component epoxy structural adhesive, prepared from the following components in parts by weight:

[0167] Bisphenol A diglycidyl ether E51 20 parts

[0168] 13 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0169] 17 parts of flexible chain modified epoxy resin

[0170] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0171] Inorganic packing HY-G5 20 parts

[0172] Latent curing agent IPH-99 8 parts

[0173] Accelerator EMI-24 2 parts

[0174] 5 parts of thixotropic agent BT-300

[0175] 4 parts of diluent PG-100.

[0176] The production steps are as follows:

[0177] (1) Bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, flexible chain modified epoxy resin, and core-shell nanoparticle toughening agent were added to a planetary mixer according to the mass fractions, and stirred and mixed for 20 min at 1000 r / min and vacuum degree -0.095 MPa.

[0178] (2) Add inorganic filler, latent curing agent, accelerator and thixotropic agent, stir at 800 r / min for 10 min with planetary mixer, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min;

[0179] (3) Add diluent, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min; discharge to obtain a single-component epoxy structural adhesive.

[0180] Example 2

[0181] This embodiment provides a one-component epoxy structural adhesive, prepared from the following components in parts by weight:

[0182] Bisphenol A diglycidyl ether E51 20 parts

[0183] 15 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0184] 15 parts of flexible chain modified epoxy resin

[0185] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0186] Inorganic packing HY-G5 20 parts

[0187] Latent curing agent IPH-99 8 parts

[0188] Accelerator EMI-24 2 parts

[0189] 5 parts of thixotropic agent BT-300

[0190] 4 parts of diluent PG-100.

[0191] The production steps are the same as in Example 1.

[0192] Example 3

[0193] This embodiment provides a one-component epoxy structural adhesive, prepared from the following components in parts by weight:

[0194] Bisphenol A diglycidyl ether E51 20 parts

[0195] 15 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0196] 13 parts of flexible chain modified epoxy resin

[0197] 13 parts of core-shell nanoparticle toughening agent NBR-300

[0198] Inorganic packing HY-G5 20 parts

[0199] Latent curing agent IPH-99 8 parts

[0200] Accelerator EMI-24 2 parts

[0201] 5 parts of thixotropic agent BT-300

[0202] 4 parts of diluent PG-100.

[0203] The production steps are the same as in Example 1.

[0204] Example 4

[0205] This embodiment provides a one-component epoxy structural adhesive, prepared from the following components in parts by weight:

[0206] Bisphenol A diglycidyl ether E51 20 parts

[0207] 10 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0208] 10 parts of flexible chain modified epoxy resin

[0209] 16 parts of core-shell nanoparticle toughening agent NBR-300

[0210] Inorganic packing HY-G5 20 parts

[0211] Latent curing agent IPH-99 8 parts

[0212] Accelerator EMI-24 2 parts

[0213] 5 parts of thixotropic agent BT-300

[0214] 4 parts of diluent PG-100.

[0215] The production steps are the same as in Example 1.

[0216] Example 5

[0217] This embodiment provides a one-component epoxy structural adhesive, prepared from the following components in parts by weight:

[0218] Bisphenol A diglycidyl ether E51 20 parts

[0219] 11 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0220] 19 parts of flexible chain modified epoxy resin

[0221] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0222] Inorganic packing HY-G5 20 parts

[0223] Latent curing agent IPH-99 8 parts

[0224] Accelerator EMI-24 2 parts

[0225] 5 parts of thixotropic agent BT-300

[0226] 4 parts of diluent PG-100.

[0227] The production steps are the same as in Example 1.

[0228] Comparative Example 1

[0229] This comparative example provides a one-component epoxy structural adhesive, which differs from Example 2 only in that an equal amount of polyurethane-modified epoxy resin EPU-133 is used instead of the flexible chain modified epoxy resin of the present invention. Specifically, it is prepared from the following components in parts by weight:

[0230] Bisphenol A diglycidyl ether E51 20 parts

[0231] 15 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0232] 15 parts of polyurethane-modified epoxy resin EPU-133

[0233] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0234] Inorganic packing HY-G5 20 parts

[0235] Latent curing agent IPH-99 8 parts

[0236] Accelerator EMI-24 2 parts

[0237] 5 parts of thixotropic agent BT-300

[0238] 4 parts of diluent PG-100.

[0239] The production steps are as follows:

[0240] (1) Bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, polyurethane modified epoxy resin, and core-shell nanoparticle toughening agent were added to a planetary mixer according to the mass fractions, and stirred and mixed for 20 min at 1000 r / min and vacuum degree -0.095 MPa.

[0241] (2) Add inorganic filler, latent curing agent, accelerator and thixotropic agent, stir at 800 r / min for 10 min with planetary mixer, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min;

[0242] (3) Add diluent, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min; discharge to obtain a single-component epoxy structural adhesive.

[0243] Comparative Example 2

[0244] This comparative example provides a one-component epoxy structural adhesive, which differs from Example 2 only in that an equal amount of silicone-modified epoxy resin ES 6862 is used instead of the flexible chain modified epoxy resin of the present invention. Specifically, it is prepared from the following components in parts by weight:

[0245] Bisphenol A diglycidyl ether E51 20 parts

[0246] 15 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0247] 15 parts of silicone-modified epoxy resin ES 6862

[0248] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0249] Inorganic packing HY-G5 20 parts

[0250] Latent curing agent IPH-99 8 parts

[0251] Accelerator EMI-24 2 parts

[0252] 5 parts of thixotropic agent BT-300

[0253] 4 parts of diluent PG-100.

[0254] The production steps are as follows:

[0255] (1) Bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, organosilicon modified epoxy resin, and core-shell nanoparticle toughening agent were added to a planetary mixer according to the mass fractions, and stirred and mixed for 20 min at 1000 r / min and vacuum degree -0.095 MPa.

[0256] (2) Add inorganic filler, latent curing agent, accelerator and thixotropic agent, stir at 800 r / min for 10 min with planetary mixer, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min;

[0257] (3) Add diluent, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min; discharge to obtain a single-component epoxy structural adhesive.

[0258] Comparative Example 3

[0259] This comparative example provides a one-component epoxy structural adhesive, which differs from Example 2 only in that it does not contain the flexible chain modified epoxy resin of this invention, and is specifically prepared from the following components in parts by weight:

[0260] Bisphenol A diglycidyl ether E51 20 parts

[0261] 15 parts of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin

[0262] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0263] Inorganic packing HY-G5 20 parts

[0264] Latent curing agent IPH-99 8 parts

[0265] Accelerator EMI-24 2 parts

[0266] 5 parts of thixotropic agent BT-300

[0267] 4 parts of diluent PG-100.

[0268] The production steps are as follows:

[0269] (1) Add epoxy resin, liquid nitrile rubber modified epoxy resin and core-shell nanoparticle toughening agent to the planetary mixer according to the mass fraction, and stir and mix for 20 min at 1000 r / min and vacuum degree -0.095 MPa.

[0270] (2) Add inorganic filler, latent curing agent, accelerator and thixotropic agent, stir at 800 r / min for 10 min with planetary mixer, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min;

[0271] (3) Add diluent, and then stir and mix at 1000 r / min and vacuum degree -0.095 MPa for 20 min; discharge to obtain a single-component epoxy structural adhesive.

[0272] Comparative Example 4

[0273] This comparative example provides a one-component epoxy structural adhesive, which differs from Example 2 only in that an equal amount of polyurethane-modified epoxy resin QR-9466 is used instead of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin. Specifically, it is prepared from the following components in parts by weight:

[0274] Bisphenol A diglycidyl ether E51 20 parts

[0275] Polyurethane modified epoxy resin QR-9466 15 parts

[0276] 15 parts of flexible chain modified epoxy resin

[0277] 11 parts of core-shell nanoparticle toughening agent NBR-300

[0278] Inorganic packing HY-G5 20 parts

[0279] Latent curing agent IPH-99 8 parts

[0280] Accelerator EMI-24 2 parts

[0281] 5 parts of thixotropic agent BT-300

[0282] 4 parts of diluent PG-100.

[0283] The production steps are the same as in Example 1.

[0284] Comparative Example 5

[0285] This comparative example provides a one-component epoxy structural adhesive, which differs from Example 2 only in that an equal amount of polyurethane-modified epoxy resin QR-9466 is used instead of carboxyl-terminated liquid nitrile butadiene rubber (CTBN) modified epoxy resin, and an equal amount of hyperbranched polymer toughening agent T054 is used instead of core-shell nanoparticle toughening agent NBR-300. Specifically, it is prepared from the following components in parts by weight:

[0286] Bisphenol A diglycidyl ether E51 20 parts

[0287] Polyurethane modified epoxy resin QR-9466 15 parts

[0288] 15 parts of flexible chain modified epoxy resin

[0289] Hyperbranched polymer toughening agent T054 11 parts

[0290] Inorganic packing HY-G5 20 parts

[0291] Latent curing agent IPH-99 8 parts

[0292] Accelerator EMI-24 2 parts

[0293] 5 parts of thixotropic agent BT-300

[0294] 4 parts of diluent PG-100.

[0295] The production steps are the same as in Example 1.

[0296] The raw material formulations for the preparation of the single-component epoxy structural adhesives in the above embodiments and comparative examples are shown in Table 1.

[0297] Table 1

[0298]

[0299] Performance testing

[0300] The properties of the single-component epoxy structural adhesives prepared in the above examples and comparative examples were tested.

[0301] Curing conditions: 120℃ × 30 min.

[0302] 1. T-peel strength and tensile shear strength

[0303] The test conditions are as follows:

[0304] T-peel strength: GB / T 2791-1995, Test method for T-peel strength of adhesives (flexible material to flexible material).

[0305] Tensile shear strength: GB / T 7124-2008, Determination of tensile shear strength (rigid material to rigid material).

[0306] The test results are shown in Table 2.

[0307] Table 2

[0308]

[0309] As can be seen from the test results in Table 2, the single-component epoxy structural adhesive of this invention exhibits good shear strength, peel strength, low-temperature shear strength at -40℃, and high-temperature shear strength at 80℃ across various substrates. This indicates that the toughness and high / low temperature resistance of the single-component epoxy structural adhesive of this invention are effectively improved, resulting in better durability and ensuring the safety of single-component epoxy structural adhesives in industrial applications.

[0310] Compared with Example 2, Comparative Example 1 used an equal amount of polyurethane-modified epoxy resin EPU-133 instead of the flexible chain modified epoxy resin of the present invention; Comparative Example 2 used an equal amount of silicone-modified epoxy resin ES 6862 instead of the flexible chain modified epoxy resin of the present invention; Comparative Example 3 did not use the flexible chain modified epoxy resin of the present invention but only used liquid nitrile rubber modified epoxy resin; Comparative Example 4 used an equal amount of polyurethane-modified epoxy resin QR-9466 instead of carboxyl-terminated liquid nitrile rubber modified epoxy resin; and Comparative Example 5 used an equal amount of polyurethane-modified epoxy resin QR-9466 instead of carboxyl-terminated liquid nitrile rubber (CTBN) modified epoxy resin. At the same time, an equal amount of hyperbranched polymer toughening agent T054 was used instead of core-shell nanoparticle toughening agent. The shear strength, peel strength, low-temperature shear strength at -40℃ and high-temperature shear strength at 80℃ of the prepared single-component epoxy structural adhesive were all significantly reduced. The results show that the flexible chain modified epoxy resin, liquid nitrile rubber modified epoxy resin, and core-shell nanoparticle toughening agent of this invention are combined to achieve synergistic toughening. When combined with appropriate curing agents, accelerators, and thixotropic agents, a single-component epoxy structural adhesive is prepared. This adhesive can not only effectively solve the thermal stress between the adhesive and the substrate during heat treatment and has good multi-substrate bonding ability, but also ensure high mechanical properties at room temperature, while improving low-temperature flexibility and high and low temperature stability, thus avoiding bonding failure caused by brittle fracture.

[0311] 2. Tensile shear strength of different substrates

[0312] Tensile shear strength tests were conducted on the five sets of example cases and three sets of comparative cases when bonding ceramics, 5754 aluminum, 6061 aluminum, 6082 aluminum, stainless steel, copper, and nickel-plated steel. The test conditions were the same as above.

[0313] As shown in Table 2, the single-component epoxy structural adhesive of this invention exhibits good adhesion strength to ceramics, 5-series aluminum, 6-series aluminum, stainless steel, nickel-plated steel, and copper substrates, and the strength values ​​remain stable after multiple tests. This demonstrates that the flexible chain modified epoxy resin of this invention can effectively improve the adhesion of the single-component structural adhesive to various substrates (especially metals), making it a single-component epoxy structural adhesive for bonding multiple substrates.

[0314] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A modified epoxy resin, characterized in that, The modified epoxy resin is obtained by reacting bisphenol A diglycidyl ether, butenedioic acid, and epoxidized soybean oil in the presence of a catalyst.

2. The modified epoxy resin as described in claim 1, characterized in that, The epoxidized soybean oil has an epoxy value of 6.0%~7.0% and an iodine value of ≤ 6.0gI2 / 100g.

3. The modified epoxy resin as described in claim 1, characterized in that, The bisphenol A diglycidyl ether is selected from at least one of E-51, E-44, and E-20; and / or, The catalyst is a quaternary ammonium salt catalyst, preferably tetrabutylammonium bromide.

4. The modified epoxy resin as described in claim 1, characterized in that, The mass ratio of bisphenol A diglycidyl ether, butenedioic acid, and epoxidized soybean oil is (2.7~3.3): (0.9~1.1): (0.9~1.1).

5. The modified epoxy resin as described in claim 1, characterized in that, The mass fraction of the catalyst is 0.3% to 0.7% of the total mass of bisphenol A diglycidyl ether, butenedioic acid, and epoxidized soybean oil.

6. The method for preparing the modified epoxy resin according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Stir the bisphenol A diglycidyl ether, butenedioic acid and epoxidized soybean oil evenly, heat to 95℃~105℃, add the catalyst, and heat to 115℃~125℃ to carry out the reaction; (2) Measure the acid value of the reactants until the acid value is <2.0 mgKOH / g to obtain the modified epoxy resin.

7. A one-component epoxy structural adhesive, characterized in that, It is prepared from raw materials comprising the following components, in parts by weight: 20-35 parts of bisphenol A diglycidyl ether 10-20 parts of liquid nitrile rubber modified epoxy resin 10-20 parts of the modified epoxy resin as described in any one of claims 1 to 5 5-20 parts of core-shell nanoparticle toughening agent 10-30 parts of inorganic filler 5-10 parts of latent curing agent Accelerator 0.5-2 parts 3-5 parts of thixotropic agent 3-5 parts diluent.

8. The one-component epoxy structural adhesive as described in claim 7, characterized in that, It is prepared from raw materials comprising the following components, in parts by weight: 20-30 parts of bisphenol A diglycidyl ether 10-15 parts of liquid nitrile rubber modified epoxy resin 10-20 parts of the modified epoxy resin 10-20 parts of core-shell nanoparticle toughening agent 15-25 parts of inorganic filler 6-9 parts of latent curing agent 1-2 parts of accelerator 3-5 parts of thixotropic agent 3-5 parts diluent.

9. The one-component epoxy structural adhesive as described in claim 7 or 8, characterized in that, The bisphenol A diglycidyl ether is selected from at least one of E-51, E-44, and E-20; and / or, The liquid nitrile rubber modified epoxy resin is selected from at least one of the following: carboxyl-terminated liquid nitrile rubber modified epoxy resin, amine-terminated liquid nitrile rubber modified epoxy resin, hydroxyl-terminated liquid nitrile rubber modified epoxy resin, and epoxy-terminated liquid nitrile rubber modified epoxy resin; and / or, The core-shell nanoparticle toughening agent is selected from at least one of silicone rubber core-shell nanoparticle toughening agents, styrene-butadiene rubber core-shell nanoparticle toughening agents, and polybutadiene rubber core-shell nanoparticle toughening agents; and / or The inorganic filler is selected from at least one of nano-calcium carbonate, heavy calcium carbonate, silica powder, mica powder, alumina, aluminum hydroxide, and talc; and / or, The latent curing agent is selected from at least one of dicyandiamide and hydrazide; and / or, The accelerator is selected from at least one of substituted ureas, imidazoles, imidazole derivatives, and aromatic amines; and / or, The thixotropic agent is selected from at least one of hydrophilic fumed silica, hydrophobic fumed silica, bentonite, polyamide wax, and hydrogenated castor oil; and / or, The diluent is selected from at least one of monofunctional reactive diluents, difunctional reactive diluents, and trifunctional reactive diluents.

10. The method for preparing a one-component epoxy structural adhesive according to any one of claims 7 to 9, characterized in that, Includes the following steps: (1) The bisphenol A diglycidyl ether, liquid nitrile rubber modified epoxy resin, modified epoxy resin and core-shell nanoparticle toughening agent are added to a planetary mixer and stirred at 800 r / min-1200 r / min and vacuum degree -0.095 MPa~ -0.1 MPa; (2) Add the inorganic filler, latent curing agent, accelerator and thixotropic agent to the planetary machine, stir and mix at 800r / min-1200r / min, and then stir and mix at 800r / min-1200r / min and vacuum degree -0.095MPa ~ -0.1 MPa; (3) Add the diluent to the planetary machine and stir and mix at 800r / min-1200r / min and vacuum degree of -0.095MPa to -0.1MPa to obtain the single-component epoxy structural adhesive.

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