Two-component polyurethane structural adhesive and its application

Abstract

This application relates to the field of structural adhesive technology, and in particular to a two-component polyurethane structural adhesive and its application, to solve the technical problems in related technologies where two-component polyurethane structural adhesives cannot simultaneously achieve safety and environmental protection, as well as rapid bonding and positioning and enhanced bonding strength. A two-component polyurethane structural adhesive includes component A and component B; based on 100 parts by weight of component A, the raw materials of component A include: 40-60 parts of a combined polyol, 2-10 parts of a composite nano-crosslinking agent, 35-50 parts of a first inorganic filler, and 1-3 parts of a dehydrating agent; based on 100 parts by weight of component B, the raw materials of component B include: 40-60 parts of a polyurethane prepolymer, 25-55 parts of a second inorganic filler, and 1-5 parts of a first silane coupling agent; the composite nano-crosslinking agent includes: inorganic nanoparticles and organic ligands grafted onto the surface of the inorganic nanoparticles; the organic ligands include: a modified silane coupling agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structural adhesive, in particular to a two-component polyurethane structural adhesive and application thereof. BACKGROUND

[0002] With the continuous improvement of people's economic level and the continuous development of technology, people's performance requirements for various products are getting higher and higher. For example, in the automotive industry, the automobile panoramic sunroof glass needs a structural adhesive with high modulus for stress buffering during the process of automobile jolting and high-speed movement. In addition, due to the limited operation time, the structural adhesive also needs to achieve rapid bonding and positioning, and has high requirements for its bonding strength.

[0003] At present, the rapid bonding and positioning of the two-component polyurethane structural adhesive mainly relies on the increase of the amount of catalyst for adjustment, but most of the catalysts used are metal organotin and metal organobismuth, which are both dangerous chemicals. They have the risk of damaging health in the production process and have the risk of environmental hazards in the automobile recycling process.

[0004] Therefore, how to provide a two-component polyurethane structural adhesive that is safe and environmentally friendly, can achieve rapid bonding and positioning, and can also consider the bonding strength has become a technical problem to be solved at present. SUMMARY

[0005] Based on this, some embodiments of the present application provide a two-component polyurethane structural adhesive and application thereof to solve the technical problem that the two-component polyurethane structural adhesive in the related art cannot consider safety and environmental protection, rapid bonding and positioning, and enhanced bonding strength.

[0006] In a first aspect, a two-component polyurethane structural adhesive is provided, comprising component A and component B;

[0007] According to 100 parts by weight of the component A, the raw materials of the component A include: 40-60 parts of combined polyol, 2-10 parts of composite nanometer crosslinking agent, 35-50 parts of first inorganic filler and 1-3 parts of water removing agent;

[0008] According to 100 parts by weight of the component B, the raw materials of the component B include: 40-60 parts of polyurethane prepolymer, 25-55 parts of second inorganic filler and 1-5 parts of first silane coupling agent;

[0009] The composite nanometer crosslinking agent includes: inorganic nano-particles and organic ligand grafted on the surface of the inorganic nano-particles.

[0010] The organic ligand includes: modified silane coupling agent, which is obtained by sequentially treating a second silane coupling agent with hydroxylation and amine saltization.

[0011] wherein the component A is a polyol component and the component B is an isocyanate component.

[0012] The isocyanate component is a key part of the cross-linking reaction. It reacts with the polyol component to form a cross-linked structure of the polyurethane. This cross-linked structure endows the polyurethane material with good physical properties, such as strength, hardness, and wear resistance. For example, in the preparation of a polyurethane structural adhesive, the cross-linked network formed by the reaction of the isocyanate component and the polyol component makes the structural adhesive have excellent bonding strength and tensile modulus.

[0013] The polyol component is mainly a compound containing a hydroxyl group (-OH), such as a combined polyol. By adjusting the molecular weight and functionality (such as the number of hydroxyl groups) of the combined polyol, the properties of the polyurethane material can be changed. The combined polyol can exemplarily include at least one of a polyester polyol and a polyether polyol, and can also include a chain extender, etc.

[0014] In addition, the polyol component and the isocyanate component can also contain some additives, water-removing agents, fillers (such as a first inorganic filler and a second inorganic filler), silane coupling agents (such as a first silane coupling agent), etc. The chain extender is a small molecular compound containing two or more active hydrogens (such as a hydroxyl group or an amine group), which can increase the length of the polyurethane molecular chain, thereby affecting the hardness and strength properties of the material; the presence of the water-removing agent can effectively remove the water in the component A, avoiding the reaction of the isocyanate and water; the filler can reduce the cost and improve some physical properties of the material, such as calcium carbonate has a reinforcing effect. By adding aluminum hydroxide in the component B, the hardness and strength of the material after curing and the thermal conductivity performance can be increased; the silane coupling agent is used to enhance the wetting performance of the inorganic filler, improve the dispersion performance of the inorganic filler, and also plays a role in enhancing the adhesion to the aluminum substrate.

[0015] The composite nano-crosslinking agent includes: inorganic nanoparticles and organic ligands grafted on the surface of the inorganic nanoparticles, the organic ligands including: a modified silane coupling agent, the modified silane coupling agent being obtained by sequentially treating a second silane coupling agent with hydroxylation and aminosaltization, on the one hand, the inorganic nanoparticles in the composite nano-crosslinking agent can play a role in reinforcing, increasing viscosity, and increasing thixotropy; on the other hand, the modified silane coupling agent on the surface of the inorganic nanoparticles in the composite nano-crosslinking agent can realize the network cross-linking of the isocyanate component and the polyol component; on the other hand, the ammonium salt in the modified silane coupling agent on the surface of the inorganic nanoparticles in the composite nano-crosslinking agent can also catalyze the reaction of the isocyanate component and the polyol component.

[0016] Optionally, the composite nano-crosslinking agent satisfies at least one of the following conditions:

[0017] (1) The inorganic nanoparticles include at least one of SiO2, TiO2, ZnO, Fe3O4, Al2O3 and aluminum hydroxide;

[0018] (2) The second silane coupling agent comprises at least one of γ-glycidoxypropyltriethoxysilane, isocyanate-based trimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane;

[0019] (3) The hydroxylating agent used in the hydroxylation includes at least one of ethanol, methanol and isopropanol;

[0020] (4) The amine salting reagent used in the amine salting treatment includes: amine compounds and inorganic acids, wherein the amine compounds include at least one of tri-n-butylamine, di-n-butylamine, triethanolamine, diethanolamine and methyldiethanolamine, and the inorganic acids include at least one of hydrochloric acid, phosphoric acid and nitric acid.

[0021] Optionally, the composite nano-crosslinking agent is obtained by sequentially hydroxylating and ammonifying the inorganic nanoparticles and the second silane coupling agent in a first solution containing a hydroxylating reagent and a second solution containing an ammonium salting reagent.

[0022] Optionally, the hydroxylating agent in the first solution comprises 20% to 95% by mass; and / or,

[0023] The hydroxylation is performed at a temperature of 65°C to 75°C for a time of 24 to 48 hours; and / or,

[0024] The mass ratio of the inorganic nanoparticles to the second silane coupling agent is 1:(0.5~1.5), and / or,

[0025] The molar ratio of the hydroxylated inorganic nanoparticles to the amine compounds contained in the ammonium salting agent is 1:(0.9~1.5).

[0026] Optionally, the polyurethane prepolymer includes: a first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer, wherein the first isocyanate-terminated prepolymer contains phthalimide groups, and the second isocyanate-terminated prepolymer is prepared using a first polyol and a first isocyanate.

[0027] Phthalimide is an organic compound whose chemical structure contains a core phthalimide structure, which is generated by the reaction of phthalic anhydride with ammonia or amine. The molecule contains a five-membered ring imine structure (-C (=O)-N-) attached to a benzene ring, which gives phthalimide special chemical properties, such as high thermal stability and mechanical properties.

[0028] The first isocyanate-terminated prepolymer can be considered a phthalimide-modified polyurethane prepolymer. The phthalimide group possesses excellent heat resistance. When introduced into component B, it synergistically enhances the mechanical properties and thermal stability of the two-component polyurethane structural adhesive through its interaction with other components. The second isocyanate-terminated prepolymer is a polyol prepolymer. Mixing it with the first isocyanate-terminated prepolymer allows for the mixing of soft and hard segments, thereby enabling the adjustment of the toughness and rigidity of the two-component polyurethane structural adhesive and its glass transition temperature (Tg) to suit applications with varying Tg requirements.

[0029] Optionally, the first polyol comprises at least one of polyether polyol and polyester polyol, and the first isocyanate comprises at least one of MDI (Diphenylmethane-4,4'-diisocyanate), HDI (Hexamethylene Diisocyanate), and IPDI (Isophorone Diisocyanate).

[0030] Optionally, the mass percentage of the end-capped isocyanate in the first isocyanate-terminated prepolymer is 6% to 12%, and the mass percentage of the end-capped isocyanate in the second isocyanate-terminated prepolymer is 6% to 20%; the mass ratio of the first isocyanate-terminated prepolymer to the second isocyanate-terminated prepolymer is 1:(0.5 to 3).

[0031] Experiments revealed that by controlling the mass percentages of end-capped isocyanate in the first and second isocyanate-terminated prepolymers within the aforementioned ranges, and by controlling the mass ratio of the first to the second isocyanate-terminated prepolymers to be 1:(0.5~3), the glass transition temperature (Tg) of the two-component polyurethane structural adhesive can be effectively increased to 50℃~60℃. Further research showed that when the Tg of this two-component polyurethane structural adhesive is 50℃~60℃... At higher temperatures, it exhibits higher energy storage modulus and shear strength (the maximum shear stress a material can withstand). For example, at temperatures of 50℃~60℃, its energy storage modulus can reach over 120 MPa, and its high-temperature shear strength can reach over 15 MPa. When applied to high-temperature environments, it can effectively improve the modulus of this two-component polyurethane structural adhesive, reducing cracking and bonding failure. This two-component polyurethane structural adhesive is particularly suitable for applications such as power batteries that require high bonding strength and elastic modulus under high-temperature conditions.

[0032] Further optionally, the number average molecular weight of the first isocyanate-terminated prepolymer is 600 g / mol to 1200 g / mol, and the number average molecular weight of the second isocyanate-terminated prepolymer is 1000 g / mol to 6000 g / mol.

[0033] Optionally, the method for preparing the polyurethane prepolymer includes:

[0034] A first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer were prepared separately.

[0035] The first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer are mixed in a certain proportion.

[0036] The polyurethane prepolymer can be prepared by first preparing a first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer separately, and then mixing the two in a certain proportion.

[0037] Optionally, the preparation of the first isocyanate-terminated prepolymer includes:

[0038] The first isocyanate-terminated prepolymer is prepared using a first acid anhydride and a second isocyanate. The first acid anhydride includes at least one of pyromellitic dianhydride and its derivatives and 4,4'-biphenyl dianhydride and its derivatives. The second isocyanate includes at least one of MDI (Diphenylmethane-4,4'-diisocyanate), HDI (Hexamethylene Diisocyanate), and IPDI (Isophorone Diisocyanate).

[0039] Optionally, the molar ratio of the first acid anhydride to the second isocyanate is 1:(2.0~2.1), the reaction temperature is 70℃~140℃, and the reaction time is 3h~6h. A first isocyanate-terminated prepolymer meeting the above performance requirements can be prepared.

[0040] Optionally, the method for preparing the polyurethane prepolymer includes:

[0041] A first reaction raw material for the first isocyanate-terminated prepolymer and a second reaction raw material for the second isocyanate-terminated prepolymer are provided;

[0042] The polyurethane prepolymer is prepared by a one-pot method, in which the first reactant and the second reactant are added in steps.

[0043] The one-pot method for preparing this polyurethane prepolymer can improve reaction efficiency.

[0044] Optionally, the first reaction raw material includes: a first acid anhydride and a second isocyanate; the second reaction raw material includes: the first polyol and the first isocyanate;

[0045] Optionally, the polyurethane prepolymer is prepared using a one-pot method by adding the first reactant and the second reactant in steps, including: under the protection of a protective gas,

[0046] The first reactant is added to the reaction vessel and reacted at a first temperature for a first time to prepare the first isocyanate-terminated prepolymer.

[0047] Cool the first isocyanate-terminated prepolymer to a second temperature;

[0048] The second reaction material is added to the cooled first isocyanate-terminated prepolymer, and the reaction is carried out at a third temperature for a second duration to prepare the polyurethane prepolymer.

[0049] Optionally, the first temperature is 70℃~140℃, and the first duration is 3h~6h; the second temperature is 50℃~80℃; and the third temperature is 70℃~90℃, and the second duration is 3h~5h.

[0050] Optionally, the two-component polyurethane structural adhesive satisfies at least one of the following conditions:

[0051] (1) The initial curing time of the two-component polyurethane structural adhesive is less than or equal to 60 min, and optionally 5 min to 30 min;

[0052] (2) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 1 hour is greater than or equal to 1.0 MPa, and optionally 1 MPa ~ 2.5 MPa;

[0053] (3) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 168 hours is greater than or equal to 18 MPa, and optionally 18 MPa ~ 25 MPa.

[0054] (4) The dynamic energy storage modulus of the two-component polyurethane structural adhesive at 60°C is greater than or equal to 120 MPa.

[0055] Secondly, the invention provides an application of the two-component polyurethane structural adhesive as described in the first aspect in the fields of rapid bonding and curing and vibration-resistant adhesives, wherein the rapid bonding and curing refers to the curing time corresponding to the shear strength after bonding and curing reaching 1.0 MPa being less than or equal to 60 min under preset conditions, and the preset conditions refer to the conditions of temperature 25°C and humidity 50%RH.

[0056] Compared with related technologies, this application has at least the following beneficial technical effects:

[0057] By adding a composite nano-crosslinking agent to the polyol component, the composite nano-crosslinking agent can promote curing and, to a certain extent, regulate the mechanical properties, modulus, and thixotropic properties of the two-component polyurethane structural adhesive. Furthermore, by controlling the amount of the composite nano-crosslinking agent and the amounts of other components in the two-component polyurethane structural adhesive, the overall thixotropic properties, viscosity, and initial curing time of the two-component polyurethane structural adhesive can be adjusted to appropriate levels. This allows for faster curing while improving the tensile strength, shear strength, and tensile modulus of the cured two-component polyurethane structural adhesive. The initial curing time is adjustable within 60 minutes, and no toxic or harmful catalysts are required during this process. This achieves rapid bonding and positioning while maintaining bond strength, thus improving the material's safety and environmental performance. This solves the technical problems in related technologies where two-component polyurethane structural adhesives cannot simultaneously achieve safety and environmental protection, rapid bonding and positioning, and enhanced bond strength.

[0058] Meanwhile, this two-component polyurethane structural adhesive also has a high modulus, which can play a good stress buffering role when applied to scenarios such as automotive panoramic sunroofs where the modulus of the structural adhesive is required. Detailed Implementation

[0059] To facilitate understanding of this application, a more comprehensive description will be provided below. It should be noted that this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0061] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0063] In this application, "at least one" means any one, any two, or more of the listed items.

[0064] In this application, the terms "combinations thereof," "any combination thereof," and "any combination thereof" as used include all suitable combinations of any two or more of the listed items.

[0065] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0066] In this application, numerical ranges are involved, and unless otherwise specified, the two endpoints of the numerical range are included.

[0067] In this application, unless otherwise specified, percentage concentrations refer to final concentrations. The final concentration refers to the percentage of the added component in the system after its addition.

[0068] In this application, temperature parameters are involved. Unless otherwise specified, both isothermal processing and processing within a certain temperature range are permitted. The isothermal processing allows temperature fluctuations within the precision range controlled by the instrument.

[0069] To address the technical problems in related technologies where two-component polyurethane structural adhesives cannot simultaneously achieve safety and environmental protection, rapid bonding and positioning, and enhanced bond strength, the specific implementation method of this application is described as follows:

[0070] In a first aspect, some embodiments of this application provide a two-component polyurethane structural adhesive, comprising: component A and component B; based on 100 parts by weight of component A, the raw materials of component A include: 40 to 60 parts of a combined polyol, 2 to 10 parts of a composite nano-crosslinking agent, 35 to 50 parts of a first inorganic filler, and 1 to 3 parts of a dehydrating agent; based on 100 parts by weight of component B, the raw materials of component B include: 40 to 60 parts of a polyurethane prepolymer, 25 to 55 parts of a second inorganic filler, and 1 to 5 parts of a first silane coupling agent; wherein, the composite nano-crosslinking agent comprises: inorganic nanoparticles and an organic ligand grafted onto the surface of the inorganic nanoparticles; the organic ligand comprises: a modified silane coupling agent, which is obtained by sequentially hydroxylating and ammonium salting a second silane coupling agent.

[0071] Among them, component A is a polyol component and component B is an isocyanate component.

[0072] The isocyanate component is the key part of the crosslinking reaction. It reacts with the polyol component to form the crosslinked structure of polyurethane. This crosslinked structure endows polyurethane materials with excellent physical properties, such as strength, hardness, and abrasion resistance. For example, in the preparation of polyurethane structural adhesives, the crosslinked network formed by the reaction of the isocyanate component and the polyol component gives the structural adhesive excellent adhesive strength and tensile modulus.

[0073] Polyol components are primarily compounds containing hydroxyl groups (-OH), such as composite polyols. The properties of polyurethane materials can be altered by adjusting the molecular weight and functionality (e.g., the number of hydroxyl groups) of the composite polyol. Composite polyols may, for example, include at least one of polyester polyols and polyether polyols, and may also include chain extenders, etc.

[0074] In addition to the above, the polyol and isocyanate components may also contain additives, dehydrating agents, fillers (such as the first and second inorganic fillers), and silane coupling agents (such as the first silane coupling agent). Chain extenders are small molecule compounds containing two or more active hydrogens (such as hydroxyl or amino groups), which can increase the length of polyurethane molecular chains, thereby affecting the material's hardness and strength. The presence of dehydrating agents can effectively remove moisture from component A, preventing the isocyanate from reacting with water. Fillers can reduce costs and improve certain physical properties of the material; for example, calcium carbonate has a reinforcing effect. Adding aluminum hydroxide to component B can increase the hardness, strength, and thermal conductivity of the cured material. Silane coupling agents are used to enhance the wetting properties of inorganic fillers, improve their dispersion properties, and simultaneously enhance adhesion to substrates such as aluminum.

[0075] The composite nano-crosslinking agent comprises inorganic nanoparticles and organic ligands grafted onto the surface of the inorganic nanoparticles. The organic ligands include a modified silane coupling agent, which is obtained by sequentially hydroxylating and ammonium salting a second silane coupling agent. On one hand, the inorganic nanoparticles in this composite nano-crosslinking agent can reinforce, increase viscosity, and enhance thixotropic properties. On the other hand, the modified silane coupling agent on the surface of the inorganic nanoparticles acts as a crosslinking agent, enabling network crosslinking of the isocyanate and polyol components. Furthermore, the ammonium salt in the modified silane coupling agent on the surface of the inorganic nanoparticles can catalyze the reaction between the isocyanate and polyol components.

[0076] In the two-component polyurethane structural adhesive provided in this application embodiment, a composite nano-crosslinking agent is added to the polyol component. This composite nano-crosslinking agent can promote curing and, to a certain extent, adjust the mechanical properties, modulus, and thixotropic properties of the two-component polyurethane structural adhesive. By controlling the amount of the composite nano-crosslinking agent and the amounts of other components included in the two-component polyurethane structural adhesive, the overall thixotropic properties, viscosity, and initial curing time of the two-component polyurethane structural adhesive can be adjusted to appropriate levels. This allows for faster curing while improving the tensile strength, shear strength, and tensile modulus of the cured two-component polyurethane structural adhesive. The initial curing time of the two-component polyurethane structural adhesive is adjustable within 60 minutes. During this process, no toxic or harmful catalysts are required. This achieves rapid bonding and positioning while maintaining bond strength, thus improving the safety and environmental performance of the material. This solves the technical problems in related technologies where two-component polyurethane structural adhesives cannot simultaneously achieve safety and environmental protection, rapid bonding and positioning, and enhanced bond strength.

[0077] Meanwhile, this two-component polyurethane structural adhesive also has a high modulus, which can play a good stress buffering role when applied to scenarios such as automotive panoramic sunroofs where the modulus of the structural adhesive is required.

[0078] The aforementioned initial curing time refers to the time elapsed from the mixing of components A and B in the two-component polyurethane structural adhesive until the adhesive initially forms a solid state and possesses a certain degree of resistance to deformation. At this stage, the adhesive's shear strength is still relatively low, but it is no longer a completely liquid state and can maintain a certain shape.

[0079] Here, the time taken for the shear strength of the initially formed solid glue to reach 1 MPa is recorded as the initial curing time.

[0080] The specific test method for shear strength is as follows: Component A and component B of the two-component polyurethane structural adhesive are mixed and applied to a metal aluminum plate (3003AL or 6061AL) with a width × length of 25mm × 100mm. Another metal aluminum plate of the same size is overlapped with the first metal aluminum plate, with an overlap area of ​​12.5mm × 25mm and an adhesive layer thickness of 0.2mm. After overlapping, the plate is clamped with metal clips and left to stand for 1 hour at room temperature of 25℃ and 50%RH. The shear strength is then tested using a tensile testing machine.

[0081] In some embodiments, the inorganic nanoparticles include at least one of SiO2, TiO2, ZnO, Fe3O4, Al2O3, and aluminum hydroxide.

[0082] In some embodiments, the second silane coupling agent comprises at least one of γ-glycidoxypropyltriethoxysilane, isocyanate-based trimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0083] In these embodiments, these silane coupling agents are low-cost and, after hydroxylation and ammonium salting, function as crosslinking agents and catalysts. They effectively shorten the initial curing time of the two-component polyurethane structural adhesive, facilitating application and assembly. Furthermore, the cured strength reaches over 1 MPa after 60 minutes of curing. Simultaneously, the shear strength of this two-component polyurethane structural adhesive after curing at room temperature (25°C) and 50% RH for 168 hours reaches over 18 MPa, demonstrating excellent mechanical properties.

[0084] In some embodiments, the hydroxylating agent used in the above hydroxylation includes at least one of ethanol, methanol, and isopropanol.

[0085] In some embodiments, the amine salting reagent used in the above-described amine salting treatment includes: amine compounds and inorganic acids, wherein the amine compounds include at least one of: tri-n-butylamine, triethanolamine, diethanolamine, and methyldiethanolamine, and the inorganic acids include at least one of: hydrochloric acid, phosphoric acid, and nitric acid.

[0086] In some embodiments, the composite nano-crosslinking agent is obtained by sequentially hydroxylating and ammonifying inorganic nanoparticles and a second silane coupling agent in a first solution containing hydroxyl-containing substances and a second solution containing ammonium salting reagent.

[0087] In some embodiments, the hydroxylating agent accounts for 20% to 95% of the mass of the first solution.

[0088] In some embodiments, the hydroxylation temperature is 65°C to 75°C and the time is 24h to 48h.

[0089] In some embodiments, the mass ratio of inorganic nanoparticles to the second silane coupling agent is 1:(0.5~1.5). The hydroxylation group on the surface of the inorganic nanoparticles reacts chemically with the hydrolyzed groups of the second silane coupling agent to achieve coating of the inorganic nanoparticles by the second silane coupling agent. By setting the mass ratio of inorganic nanoparticles to the second silane coupling agent to 1:(0.5~1.5), the initial solidification time can be adjusted to be shorter.

[0090] In some embodiments, the molar ratio of the hydroxylated inorganic nanoparticles to the amine compound contained in the ammonium salting agent is 1:(0.9~1.5).

[0091] In some embodiments, the first inorganic filler comprises at least one of heavy calcium carbonate and nano-calcium carbonate. To improve the dispersion performance of the first inorganic filler in component A, the surface of the heavy calcium carbonate may be modified with calcium stearate or octadecyl alcohol, and the surface of the nano-calcium carbonate may be connected with a modifier, which may include at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0092] In these embodiments, the first inorganic filler acts as a reinforcing agent, which can improve the adhesive strength and mechanical properties of the two-component polyurethane structural adhesive.

[0093] In some embodiments, the dehydrating agent described above includes a molecular sieve.

[0094] In some embodiments, the second inorganic filler comprises carbon black and aluminum hydroxide, wherein the mass ratio of carbon black to aluminum hydroxide is (10~25):(15~30).

[0095] In these embodiments, by limiting the mass ratio of carbon black to aluminum hydroxide within the above-mentioned range, better reinforcement, thermal conductivity and modulus can be achieved, which can further improve the adhesion performance, high-temperature thermal conductivity and high-temperature modulus of the two-component polyurethane structural adhesive.

[0096] In some embodiments, the first silane coupling agent comprises at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0097] In these embodiments, the first silane coupling agent can better disperse the second inorganic filler in component B.

[0098] In some embodiments, the polyurethane prepolymer comprises: a first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer, wherein the first isocyanate-terminated prepolymer contains phthalimide groups, and the second isocyanate-terminated prepolymer is prepared using a first polyol and a first isocyanate.

[0099] Phthalimide is an organic compound whose chemical structure contains a core phthalimide structure, which is generated by the reaction of phthalic anhydride with ammonia or amine. The molecule contains a five-membered ring imine structure (-C (=O)-N-) attached to a benzene ring, which gives phthalimide special chemical properties, such as high thermal stability and mechanical properties.

[0100] In these embodiments, the first isocyanate-terminated prepolymer can be considered as an phthalimide-modified polyurethane prepolymer. The phthalimide group possesses excellent heat resistance, and when introduced into component B, it synergistically enhances the mechanical properties and thermal stability of the two-component polyurethane structural adhesive through its interaction with other components. The second isocyanate-terminated prepolymer is a polyol prepolymer. Mixing it with the first isocyanate-terminated prepolymer allows for the mixing of soft and hard segments, thereby enabling the adjustment of the toughness and rigidity of the two-component polyurethane structural adhesive and its glass transition temperature (Tg) to suit applications with varying Tg requirements.

[0101] In some embodiments, the first polyol may include at least one of polyether polyol and polyester polyol, and the first isocyanate may include at least one of diphenylmethane-4,4'-diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

[0102] In some embodiments, the mass percentage of the end-capped isocyanate in the first isocyanate-terminated prepolymer is 6% to 12%, and the mass percentage of the end-capped isocyanate in the second isocyanate-terminated prepolymer is 6% to 20%; the mass ratio of the first isocyanate-terminated prepolymer to the second isocyanate-terminated prepolymer is 1:(0.5 to 3).

[0103] In these embodiments, experiments revealed that by controlling the mass percentage of end-capped isocyanate in the first isocyanate-terminated prepolymer and the mass percentage of end-capped isocyanate in the second isocyanate-terminated prepolymer to be within the aforementioned ranges, and by controlling the mass ratio of the first isocyanate-terminated prepolymer to the second isocyanate-terminated prepolymer to be 1:(0.5~3), the glass transition temperature (Tg) of the two-component polyurethane structural adhesive can be effectively increased to 50℃~60℃. Furthermore, research showed that when the glass transition temperature (Tg) of the two-component polyurethane structural adhesive is 50℃... At ~60℃, it exhibits high energy storage modulus and shear strength (the maximum shear stress the material can withstand) at higher temperatures. For example, at temperatures of 50℃~60℃, its energy storage modulus can reach over 120 MPa, and its high-temperature shear strength can reach over 15 MPa. When applied to high-temperature scenarios, it can effectively improve the modulus of this two-component polyurethane structural adhesive and reduce cracking and bonding failure. This two-component polyurethane structural adhesive is particularly suitable for applications such as power batteries that require high bonding strength and elastic modulus under high-temperature environments.

[0104] In some embodiments, the number average molecular weight of the first isocyanate-terminated prepolymer is 600 g / mol to 1200 g / mol, and the number average molecular weight of the second isocyanate-terminated prepolymer is 1000 g / mol to 6000 g / mol.

[0105] In some embodiments, the method for preparing the polyurethane prepolymer includes:

[0106] A first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer were prepared respectively.

[0107] The first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer are mixed in a certain proportion.

[0108] In these embodiments, a first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer can be prepared separately, and then the two can be mixed in a certain proportion to prepare the polyurethane prepolymer.

[0109] In some embodiments, the preparation of the first isocyanate-terminated prepolymer includes:

[0110] A first isocyanate-terminated prepolymer is prepared using a first acid anhydride and a second isocyanate. The first acid anhydride includes at least one of pyromellitic dianhydride and its derivatives and 4,4'-biphenyl dianhydride and its derivatives. The second isocyanate includes at least one of MDI (Diphenylmethane-4,4'-diisocyanate), HDI (Hexamethylene Diisocyanate), and IPDI (Isophorone Diisocyanate).

[0111] In some embodiments, the molar ratio of the first anhydride to the second isocyanate is 1:(2.0~2.1), the reaction temperature is 70℃~140℃, and the reaction time is 3h~6h.

[0112] In these embodiments, a first isocyanate-terminated prepolymer that meets the above performance requirements can be prepared.

[0113] In some embodiments, the first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer are mixed in proportion, which can be carried out under heating conditions, with the heating temperature being 50°C to 80°C and the mixing time being 30 min to 60 min.

[0114] In some embodiments, the method for preparing the polyurethane prepolymer includes:

[0115] A first reactant material for the first isocyanate-terminated prepolymer and a second reactant material for the second isocyanate-terminated prepolymer are provided;

[0116] Polyurethane prepolymers were prepared using a one-pot method by adding the first and second reactants in steps.

[0117] In these embodiments, the polyurethane prepolymer can be prepared using a one-pot method, which improves reaction efficiency.

[0118] In some embodiments, a polyurethane prepolymer is prepared by a one-pot method by adding a first reactant and a second reactant in steps, comprising: adding a first reactant to a reaction vessel under the protection of a protective gas, reacting at a first temperature for a first time, and preparing a first isocyanate-terminated prepolymer.

[0119] Cool the first isocyanate-terminated prepolymer to a second temperature;

[0120] A second reactant is added to the cooled first isocyanate-terminated prepolymer, and the reaction is carried out at a third temperature for a second duration to prepare a polyurethane prepolymer.

[0121] In these embodiments, a first isocyanate-terminated prepolymer is prepared first, and then the temperature is lowered to a second temperature. This allows the first and second isocyanate-terminated prepolymers to react sequentially at their respective reaction temperatures. When preparing the second isocyanate-terminated prepolymer at a lower temperature, the first and second isocyanate-terminated prepolymers can be mixed by stirring, avoiding additional mixing steps.

[0122] In some embodiments, the first temperature is 70℃~140℃, the first duration is 3h~6h; the second temperature is 50℃~80℃; the third temperature is 70℃~90℃, and the second duration is 3h~5h.

[0123] In some embodiments, the molar ratio of the first acid anhydride and the second isocyanate in the first reaction raw material can be 1:(2.0~2.1), and the molar ratio of the first polyol and the first isocyanate in the second reaction raw material can be 1:(1.0~4.0).

[0124] In some embodiments, the two-component polyurethane structural adhesive satisfies at least one of the following conditions:

[0125] (1) The initial curing time of the two-component polyurethane structural adhesive is less than or equal to 60 min, and optionally 5 min to 30 min;

[0126] (2) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 1 hour is greater than or equal to 1.0 MPa, and optionally 1.0 MPa ~ 2.5 MPa;

[0127] (3) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 168 hours is greater than or equal to 18 MPa, and optionally 18 MPa ~ 25 MPa.

[0128] (4) The dynamic energy storage modulus of the two-component polyurethane structural adhesive at 60℃ is greater than or equal to 120MPa.

[0129] The definition of initial settling time can be found in the preceding description and will not be repeated here.

[0130] In these embodiments, when the initial curing time of the two-component polyurethane structural adhesive is less than or equal to 60 min, the two-component polyurethane structural adhesive has a short initial curing time, which can achieve rapid bonding and positioning; when the shear strength of the two-component polyurethane structural adhesive after curing for 1 h at 25°C and 50%RH is greater than or equal to 1.0 MPa, the two-component polyurethane structural adhesive can achieve high bonding strength in a short time, which is convenient for application and production assembly; when the shear strength of the two-component polyurethane structural adhesive after curing for 168 h at 25°C and 50%RH is greater than or equal to 18 MPa, the two-component polyurethane structural adhesive has high shear strength; when the dynamic energy storage modulus of the two-component polyurethane structural adhesive at 60°C is greater than or equal to 120 MPa, the two-component polyurethane structural adhesive is suitable for applications such as power batteries that have high requirements for bonding strength and elastic modulus under high temperature environments.

[0131] Secondly, some embodiments of this application provide an application of the two-component polyurethane structural adhesive as described in the first aspect in the fields of rapid bonding and curing and vibration-resistant adhesives. The rapid bonding and curing refers to the curing time corresponding to the shear strength reaching 1.0 MPa after bonding and curing under preset conditions being less than or equal to 60 min. The preset conditions refer to a temperature of 20℃~30℃ and a humidity of 45%RH~55%RH.

[0132] In some embodiments, when the polyurethane prepolymer in component B of the two-component polyurethane structural adhesive includes a first isocyanate-terminated prepolymer containing phthalimide groups, the two-component polyurethane structural adhesive also has a relatively high energy storage modulus at higher temperatures, making it particularly suitable for applications such as power batteries that require high bonding strength and elastic modulus under high-temperature environments.

[0133] For example, when this two-component polyurethane structural adhesive is used in power batteries, it can withstand high temperatures and has a high energy storage modulus at 50°C to 60°C. This can improve the bonding stability of the power battery at high temperatures and reduce problems such as cracking and bonding failure.

[0134] The specific implementation methods of this application have been described above. In order to objectively illustrate the technical effects produced by this application, the following examples and comparative examples will be used to describe them in detail.

[0135] In the following examples and comparative examples, all raw materials were commercially available, and to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples had the same physical and chemical parameters or underwent the same treatment.

[0136] The main raw material information used in the following embodiments and comparative examples is shown in Table 1 below:

[0137] Table 1

[0138]

[0139] Example 1

[0140] Example 1 provides a two-component polyurethane structural adhesive, the preparation method of which is as follows:

[0141] (1) To prepare the composite nano-crosslinking agent, 50.0 g of fumed silica (from Cabot Corporation fumed silica M5) aqueous solution (20%) was ultrasonically dispersed for 1 h. The γ-glycidyl etheroxypropyltrimethoxysilane coupling agent (from Momentive silane coupling agent A-187) and inorganic nanoparticles were mixed in a four-necked flask at a mass ratio of 1:1. 50.0 g of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent dissolved in 75.0 g ethanol solution (95% mass concentration) and inorganic nanoparticles were mixed and activated at 70 °C for 24 h to obtain activated inorganic nanoparticles. 48.9 g of tri-n-butylamine (purchased from Sinopharm Reagent) and 26.7 g of 37% hydrochloric acid solution were added to the above activation system and stirred at 80 °C. After reacting under nitrogen protection for 5 h, the solvent was evaporated by rotary evaporation. After washing with anhydrous ethanol, the mixture was dried at 80 °C to obtain the composite nano-crosslinking agent.

[0142] (2) Preparation of the first isocyanate prepolymer: 21.8 parts by weight of pyromellitic dianhydride (purchased from Sinopharm Reagent) and 28.2 parts by weight of NMP (from Wanhua NMP-10) were mixed and heated at 80°C to dissolve the pyromellitic dianhydride (PMDA). 50.0 parts by weight of diphenylmethane diisocyanate (from Wanhua MDI-100) baked at 80°C were added. The mixture was reacted at 125°C for 4 hours under nitrogen protection. After cooling, the mass ratio of the end-capped isocyanate was tested and found to be 8.4 ± 0.5%. The mixture was then cooled and left to stand for use. The first isocyanate prepolymer (number average molecular weight 630.6) was obtained.

[0143] (3) Preparation of the second isocyanate prepolymer: 56.87 parts by weight of bio-based castor oil polyol (from BASF Sovermol805, hydroxyl value 170, functionality 3.5) and 43.13 parts by weight of pre-baked diphenylmethane diisocyanate (from Wanhua MDI-100) were added to the synthesis reactor, heated to 80°C, and stirred for 2-3 hours. When the mass ratio of NCO at the end cap was 7.3±0.5wt%, vacuum degassing was started. The synthesis reaction was stopped after 30 minutes of degassing to obtain the second isocyanate prepolymer (number average molecular weight about 1400).

[0144] (4) PART-A preparation: 27.32 parts by weight of polyether triol 1 (from Wanhua Chemical F3128, number average molecular weight 6000, hydroxyl value 28, functionality 3), 1.5 parts by weight of polyether triol 3 (from Wanhua Chemical R2304, number average molecular weight 400, hydroxyl value 420.75, functionality 3), 27.32 parts by weight of bio-based castor oil polyol (from BASF Sovermol805, hydroxyl value 170, functionality 3.5) were added to a mixing vessel and stirred under vacuum for 30 min. Then, 39.66 parts by weight of calcium carbonate (from Omia 120-F0) and 2.2 parts by weight of the composite nano crosslinking agent prepared in step (1) of Example 1, as well as 2.0 parts by weight of 4A molecular sieve (from Jianlong Vina) were added to the mixing vessel and stirred under vacuum for 1 h to disperse and degas. The mixture was then sealed in a two-component equal-volume plastic tube and kept for later use.

[0145] (5) Preparation of PART-B: 38 parts by weight of the second isocyanate-terminated prepolymer and 15 parts by weight of the first isocyanate-terminated prepolymer were mixed at 60°C under nitrogen protection for 30 min to prepare a mixture of the first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer. Under nitrogen protection, 10 parts by weight of carbon black (570 from Cabot Corporation), 35 parts by weight of aluminum hydroxide (KA-5D from Sichuan Huaya) and 2 parts by weight of γ-(2,3-epoxypropoxy)propyltrimethoxysilane oligomer (MP200 from Momentive) were added to the mixture in sequence. The mixture was stirred and vacuum degassed for 1 h to obtain the PART-B component. The mixture was then sealed in a two-component equal-volume plastic tube for later use.

[0146] Example 2

[0147] The preparation method of the two-component polyurethane structural adhesive provided in Example 2 is basically the same as that of the two-component polyurethane structural adhesive provided in Example 1, except that:

[0148] In step (5), the mass fraction of the first isocyanate-terminated prepolymer in PART-B is 16 parts, and the mass fraction of aluminum hydroxide is 34 parts, as shown in Table 2.

[0149] Example 3

[0150] The preparation method of the two-component polyurethane structural adhesive provided in Example 3 is basically the same as that of the two-component polyurethane structural adhesive provided in Example 1, except that:

[0151] In step (5), the mass fraction of the first isocyanate-terminated prepolymer in PART-B is 17 parts, and the mass fraction of aluminum hydroxide is 33 parts, as shown in Table 2.

[0152] Example 4

[0153] The preparation method of the two-component polyurethane structural adhesive provided in Example 4 is basically the same as that of the two-component polyurethane structural adhesive provided in Example 1, except that:

[0154] In step (5), the mass fraction of the first isocyanate-terminated prepolymer in PART-B is 19 parts, and the mass fraction of aluminum hydroxide is 32 parts, as shown in Table 2.

[0155] Example 5

[0156] The preparation method of the two-component polyurethane structural adhesive provided in Example 5 is basically the same as that of the two-component polyurethane structural adhesive provided in Example 1, except that:

[0157] The first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer in steps (2) and (3) were prepared by a one-pot method:

[0158] 7.07 parts by weight of pyromellitic dianhydride (purchased from Sinopharm Reagent) and 7.07 parts by weight of NMP (from Wanhua NMP-10) were heated and stirred at 80°C under nitrogen protection for 1 hour to completely dissolve the pyromellitic dianhydride. Then, 16.22 parts by weight of pre-baked diphenylmethane diisocyanate (from Wanhua MDI-100) were added, the temperature was raised to 125°C, and the reaction was carried out under nitrogen protection for 5 hours. The mass percentage of end-capped NCO was measured to be 8.4 ± 0.5%, and the temperature was lowered to 70°C. Add 43.21 parts by weight of pre-baked diphenylmethane diisocyanate (from Wanhua MDI-100), mix for 20 min, then add 26.42 parts by weight of bio-based castor oil polyol (from BASF Sovermol 805, hydroxyl value 170, functionality 3.5), and maintain the reaction temperature at 80℃ for 4 h under nitrogen protection to obtain a mixture of the first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer with a mass ratio of 15:38. The total mass percentage of NCO in the mixture was measured to be 7.6 ± 0.5%.

[0159] In step (5), 53 parts by weight of the mixture prepared by the above method are used to replace 15 parts by weight of the first isocyanate prepolymer and 38 parts by weight of the second isocyanate prepolymer.

[0160] Table 2

[0161]

[0162] Comparative Example 1

[0163] The preparation method of the two-component polyurethane structural adhesive provided in Comparative Example 1 is basically the same as that of the two-component polyurethane structural adhesive provided in Example 1, except that:

[0164] In PART-A, 4.7 parts by weight of fumed silica (from Evonik's R202) and 0.1 parts by weight of dibutyltin dilaurate (from Evonik) were used to replace 4.8 parts by weight of the composite nano-crosslinking agent.

[0165] PART-B does not contain the first isocyanate end-capping prepolymer: PART-B is prepared by directly mixing 53 parts by weight of the second isocyanate prepolymer with 10 parts by weight of carbon black, 35 parts by weight of aluminum hydroxide and 2 parts by weight of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and degassing.

[0166] Test case

[0167] 1. The two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 were mixed with PART-A and PART-B in a mass ratio of 1:1 using a glue gun and then applied. The glass transition temperature of the samples after applying the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 was tested using DSC. The heating temperature during the test was -50℃ to 200℃, and the heating rate was 5℃ / min. The test results are shown in Table 3 below.

[0168] 2. The two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 were used to prepare hardness test samples with a thickness greater than 6 mm. After complete curing, the hardness of the samples was tested with a Shore A hardness tester according to GBT 531.1-2008 Vulcanized Rubber Indentation Hardness Test Method. The test results are shown in Table 3 below.

[0169] Table 3

[0170]

[0171] As shown in Table 3, Examples 1-5 of this application have higher Tg and higher curing hardness compared to Comparative Example 1, and better mechanical properties.

[0172] 3. Take the two-component polyurethane structural adhesive provided in Examples 1-5 and Comparative Example 1 respectively to prepare aluminum plate shearing samples. The aluminum plate is selected from 3003AL or 6061AL. The aluminum plate size is 100mm long × 25mm wide × 2mm thick. The adhesive thickness is 0.2mm and the overlap area is 12.5mm.

[0173] According to GB / T 7124-2008 "Test Method for Tensile Shear Strength of Adhesives", the shear sample was left to stand for 1 hour at 25℃ and 50%RH, and then the shear strength test was immediately performed. The test conditions were a tensile speed of 5 mm / min, an adhesive layer thickness of 0.2 mm, and an ambient temperature of 25℃. The bonding performance of the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 was judged after 1 hour of application. The test results are shown in Table 4 below.

[0174] Table 4

[0175]

[0176] As shown in Table 4, compared with Comparative Example 1, the two-component polyurethane structural adhesive provided in this application embodiment has a shorter curing time, which can achieve rapid bonding and curing.

[0177] 4. Take the two-component polyurethane structural adhesive provided in Examples 1-5 and Comparative Example 1 respectively to prepare aluminum plate shear samples. The aluminum plate is selected from 3003AL or 6061AL. The aluminum plate size is 100mm long × 25mm wide × 2mm thick. The adhesive thickness is 0.2mm and the overlap area is 12.5mm.

[0178] According to GB / T 7124-2008 "Test Method for Tensile Shear Strength of Adhesives", after curing at room temperature (25℃) and 50%RH for 168 hours, the samples were subjected to shear tests in environmental conditions or in a heating chamber at 25℃, 60℃ and 80℃ (no humidity requirement, but preheating of the shear test specimen is required for high-temperature shearing). The tensile speed was 5 mm / min. The test results are shown in Table 5 below.

[0179] According to standard GB / T 16997-1997 "Representation of Main Failure Types of Adhesives", the failure types of the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 were tested at different temperatures (e.g., 25℃, 60℃ and 80℃) after application to determine the strength of the adhesive properties of the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1. The test results are shown in Table 5 below.

[0180] Table 5

[0181]

[0182] As shown in Table 5, compared to Comparative Example 1, the two-component polyurethane structural adhesive provided in this application embodiment exhibits higher shear strength at different temperatures, thus improving adhesion performance at high temperatures. 100% CF indicates that there is adhesive residue on both surfaces after failure.

[0183] 5. Take the two-component polyurethane structural adhesive provided in Examples 1-5 and Comparative Example 1 respectively to prepare aluminum plate shear samples. The aluminum plate is selected from 3003AL or 6061AL. The aluminum plate size is 100mm long × 25mm wide × 2mm thick. The adhesive thickness is 0.2mm and the overlap area is 12.5mm.

[0184] The samples of the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1, after curing for 168 hours, were subjected to 1000 cycles of thermal shock. The test conditions were -40℃ to 80℃, with a temperature transition time of 30 minutes and a holding time of 8 hours for each extreme environment (i.e., holding at -40℃ for 8 hours, then programmed temperature rise: 30 minutes to 80℃, holding at 80℃ for 8 hours, then programmed temperature drop: 30 minutes to -40℃, followed by a second thermal shock, and so on, to achieve 1000 thermal shock cycles). After the thermal shock cycle was completed and the samples were placed at room temperature for 24 hours, the shear strength of the samples was tested according to GB / T 7124-2008 "Test Method for Tensile Shear Strength of Adhesives". The tensile speed was 5 mm / min, and the test results are shown in Table 6 below.

[0185] 6. Fully cured DMA samples prepared with the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 were taken respectively. The test conditions were as follows: sample size (thickness × width × length) between 1×5×20 mm and 1×10×50 mm; temperature range of -40℃ to 85℃; heating rate of 1℃ / min; tensile clamps; vibration frequency of 1Hz; and amplitude of 0.1%. The dynamic storage modulus of the fully cured DMA samples prepared with the two-component polyurethane structural adhesives provided in Examples 1-5 and Comparative Example 1 at 60℃ was tested. The test results are shown in Table 6 below.

[0186] Table 6

[0187]

[0188] As shown in Table 6, compared with Comparative Example 1, the two-component polyurethane structural adhesive provided in this application embodiment has good high and low temperature impact resistance, can withstand aging for a long time, and has a high high temperature energy storage modulus, making it suitable for use in power batteries.

[0189] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0190] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A two-component polyurethane structural adhesive, characterized in that, Includes component A and component B; Based on 100 parts by weight of component A, the raw materials of component A include: 40 to 60 parts of combined polyol, 2 to 10 parts of composite nano crosslinking agent, 35 to 50 parts of first inorganic filler, and 1 to 3 parts of dehydrating agent; Based on 100 parts by weight of component B, the raw materials of component B include: 40 to 60 parts of polyurethane prepolymer, 25 to 55 parts of second inorganic filler, and 1 to 5 parts of first silane coupling agent. The composite nano-crosslinking agent is obtained by sequentially hydroxylating and ammonifying inorganic nanoparticles and a second silane coupling agent in a first solution containing a hydroxylating reagent and a second solution containing an ammonium salting reagent; the mass ratio of the inorganic nanoparticles to the second silane coupling agent is 1:(0.5~1.5); in the first solution, the mass percentage of the hydroxylating reagent is 20%~95%; the molar ratio of the hydroxyl groups of the hydroxylated inorganic nanoparticles to the amine compounds contained in the ammonium salting reagent is 1:(0.9~1.5).

2. The two-component polyurethane structural adhesive according to claim 1, characterized in that, The composite nano-crosslinking agent satisfies at least one of the following conditions: (1) The inorganic nanoparticles include: At least one of SiO2, TiO2, ZnO, Fe3O4, Al2O3 and aluminum hydroxide; (2) The second silane coupling agent comprises at least one of γ-glycidoxypropyltrimethoxysilane, isocyanate-based trimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane; (3) The hydroxylating agent used in the hydroxylation includes at least one of ethanol, methanol and isopropanol; (4) The amine salting reagent used in the amine salting treatment includes amine compounds and inorganic acids, wherein the amine compounds include at least one of tri-n-butylamine, di-n-butylamine, triethanolamine, diethanolamine, monoethanolamine and methyldiethanolamine, and the inorganic acids include at least one of hydrochloric acid, phosphoric acid and nitric acid.

3. The two-component polyurethane structural adhesive according to claim 1, characterized in that, The hydroxylation is performed at a temperature of 65°C to 75°C for a time of 24 to 48 hours.

4. The two-component polyurethane structural adhesive according to claim 1, characterized in that, The polyurethane prepolymer includes: a first isocyanate-terminated prepolymer and a second isocyanate-terminated prepolymer, wherein the first isocyanate-terminated prepolymer contains phthalimide groups, and the second isocyanate-terminated prepolymer is prepared using a first polyol and a first isocyanate.

5. The two-component polyurethane structural adhesive according to claim 4, characterized in that, The first polyol includes at least one of polyether polyol and polyester polyol, and the first isocyanate includes at least one of diphenylmethane-4,4'-diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

6. The two-component polyurethane structural adhesive according to claim 4, characterized in that, The mass percentage of the end-capped isocyanate in the first isocyanate-terminated prepolymer is 6% to 12%, and the mass percentage of the end-capped isocyanate in the second isocyanate-terminated prepolymer is 6% to 20%; the mass ratio of the first isocyanate-terminated prepolymer to the second isocyanate-terminated prepolymer is 1:(0.5 to 3).

7. The two-component polyurethane structural adhesive according to claim 4, characterized in that, The number average molecular weight of the first isocyanate-terminated prepolymer is 600 g / mol to 1200 g / mol, and the number average molecular weight of the second isocyanate-terminated prepolymer is 1000 g / mol to 6000 g / mol.

8. The two-component polyurethane structural adhesive according to claim 4, characterized in that, The method for preparing the polyurethane prepolymer includes: The first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer were prepared separately. The first isocyanate-terminated prepolymer and the second isocyanate-terminated prepolymer are mixed in a certain proportion.

9. The two-component polyurethane structural adhesive according to claim 8, characterized in that, The preparation of the first isocyanate-terminated prepolymer includes: The first isocyanate-terminated prepolymer is prepared using a first acid anhydride and a second isocyanate. The first acid anhydride includes at least one of pyromellitic dianhydride and its derivatives and 4,4'-biphenyl dianhydride and its derivatives. The second isocyanate includes at least one of diphenylmethane-4,4'-diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

10. The two-component polyurethane structural adhesive according to claim 9, characterized in that, The molar ratio of the first acid anhydride to the second isocyanate is 1:(2.0~2.1), the reaction temperature is 70℃~140℃, and the reaction time is 3h~6h.

11. The two-component polyurethane structural adhesive according to claim 4, characterized in that, The method for preparing the polyurethane prepolymer includes: A first reaction raw material for the first isocyanate-terminated prepolymer and a second reaction raw material for the second isocyanate-terminated prepolymer are provided; The polyurethane prepolymer is prepared by a one-pot method, in which the first reactant and the second reactant are added in steps.

12. The two-component polyurethane structural adhesive according to claim 11, characterized in that, The first reaction raw material includes: a first acid anhydride and a second isocyanate; the second reaction raw material includes: the first polyol and the first isocyanate.

13. The two-component polyurethane structural adhesive according to claim 11, characterized in that, The polyurethane prepolymer is prepared by a one-pot method using a stepwise addition of the first and second reactants, comprising: under the protection of a protective gas... The first reactant is added to the reaction vessel and reacted at a first temperature for a first time to prepare the first isocyanate-terminated prepolymer. Cool the first isocyanate-terminated prepolymer to a second temperature; The second reaction material is added to the cooled first isocyanate-terminated prepolymer, and the reaction is carried out at a third temperature for a second duration to prepare the polyurethane prepolymer.

14. The two-component polyurethane structural adhesive according to claim 13, characterized in that, The first temperature is 70℃~140℃, and the first duration is 3h~6h; the second temperature is 50℃~80℃; the third temperature is 70℃~90℃, and the second duration is 3h~5h.

15. The two-component polyurethane structural adhesive according to any one of claims 1 to 14, characterized in that, The two-component polyurethane structural adhesive satisfies at least one of the following conditions: (1) The initial curing time of the two-component polyurethane structural adhesive is less than or equal to 60 min; (2) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 1 hour is greater than or equal to 1.0 MPa. (3) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 168 hours is greater than or equal to 18MPa. (4) The dynamic energy storage modulus of the two-component polyurethane structural adhesive at 60°C is greater than or equal to 120 MPa.

16. The two-component polyurethane structural adhesive according to claim 15, characterized in that, The two-component polyurethane structural adhesive satisfies at least one of the following conditions: (1) The initial curing time of the two-component polyurethane structural adhesive is 5 min to 30 min; (2) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 1 hour is 1.0 MPa ~ 2.5 MPa; (3) The shear strength of the two-component polyurethane structural adhesive after curing at 25°C and 50%RH for 168 hours is 18 MPa ~ 25 MPa.

17. The application of a two-component polyurethane structural adhesive as described in any one of claims 1 to 16 in the fields of rapid bonding and curing and vibration-resistant adhesives, characterized in that, The rapid bonding and curing refers to the curing time being less than or equal to 60 minutes when the shear strength after bonding and curing reaches 1.0 MPa under preset conditions. The preset conditions are a temperature of 20℃~30℃ and a humidity of 45%RH~55%RH.

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