Epoxy hybrid polyurethane adhesive and preparation method thereof

Abstract

The invention discloses an epoxy hybrid polyurethane adhesive and a preparation method thereof, and belongs to the field of polyurethane adhesives. The epoxy hybrid polyurethane adhesive is prepared from the following raw materials in parts by mass: 15 to 30 parts of polyurethane prepolymer, 5 to 20 parts of epoxy resin, 30 to 40 parts of inorganic filler, 1 to 5 parts of difunctional POSS (Polyhedral Oligomeric Silsesquioxane), 10 to 15 parts of plasticizer and 0.1 to 2 parts of antioxidant, the polyurethane prepolymer comprises an isocyanate-terminated polyurethane prepolymer and an epoxy-terminated modified polyurethane prepolymer in a mass ratio of (10-20): (5-10); and a polysiloxane chain segment and a secondary amine functional chain segment are grafted on the epoxy-terminated modified polyurethane prepolymer. The epoxy-terminated modified polyurethane prepolymer is terminated by epoxy, a grafted polysiloxane chain segment can block permeation of water molecules, a secondary amine functional chain segment can play a role of a chain extender, extension of a polyurethane molecular chain is helped, and finally the epoxy hybrid polyurethane adhesive with high thermal stability and high tensile strength is promoted to be obtained.

Description

Technical Field

[0001] This invention relates to the field of polyurethane adhesives, and particularly to an epoxy hybrid polyurethane adhesive and its preparation method. Background Technology

[0002] Polyurethane adhesives are adhesives whose molecular chains contain urethane groups and / or isocyanate groups. The large number of urethane, urethane, biuret and other groups in their molecular chains endow polyurethane adhesives with excellent properties, such as good mechanical properties, acid and alkali resistance, oil resistance and good adhesion to substrates. These properties make them widely used in industries such as electronics, construction, automobiles, flexible packaging and wood processing.

[0003] However, with social progress and development, the single properties of polyurethane adhesives can no longer meet application requirements. Modification of polyurethane adhesives has become the main means to expand their application fields. Among these methods, chemical modification of polyurethane, which utilizes polymer chemical reactions to change the types of atoms or groups on the polyurethane adhesive molecular chain and their bonding mode, can effectively compensate for the inherent defects of polyurethane adhesives.

[0004] Epoxy resins possess high strength, good adhesion, and corrosion resistance. Furthermore, epoxy resins can undergo graft polymerization with the active isocyanate groups in polyurethane molecules. Therefore, introducing epoxy resins into polyurethane adhesives can significantly improve the material's water resistance and strength. However, the urethane bonds in the polyurethane molecular chain are prone to hydrolytic breakage under humid and hot environments. Epoxy resins also introduce a large number of hydroxyl groups during modification, resulting in high water absorption under humid and hot conditions, which further leads to thermal oxidative decomposition. Consequently, the modified polyurethane adhesives still suffer from poor resistance to humid heat and poor thermal stability.

[0005] Furthermore, while the addition of epoxy resin can increase the crosslinking density of the adhesive, excessive epoxy resin can lead to increased system viscosity and excessive cohesion, which in turn hinders the movement of molecular chains and reduces long-term thermal stability. Simultaneously, to improve the stability of epoxy-modified polyurethane adhesives, hydrophilic chain extenders are often added. However, excessive introduction of flexible segments and hydrophilic groups through hydrophilic chain extenders can weaken the hydrogen bonding between hard segments, resulting in a decrease in tensile strength.

[0006] Therefore, it is of great significance to obtain an epoxy-modified polyurethane adhesive with good thermal stability, resistance to damp heat, and high tensile strength. Summary of the Invention

[0007] This invention provides an epoxy hybrid polyurethane adhesive and its preparation method, which can solve the problems of poor thermal stability, poor resistance to damp heat and low tensile strength of existing epoxy modified polyurethane adhesives.

[0008] In a first aspect, the present invention provides an epoxy hybrid polyurethane adhesive, comprising the following raw materials in parts by weight: 15-30 parts of polyurethane prepolymer; 5-20 parts epoxy resin; 30-40 parts of inorganic filler; Dual-function POS systems: 1-5 copies; Plasticizer 10-15 parts; Antioxidant 0.1 to 2 parts; Polyurethane prepolymers include isocyanate-terminated polyurethane prepolymers and epoxy-terminated polyurethane prepolymers with a mass ratio of (10-20):(5-10). The epoxy-modified polyurethane prepolymer is grafted with polysiloxane segments and secondary amine functional segments.

[0009] Preferably, the inorganic filler includes one or more combinations of montmorillonite, silica fume and talc.

[0010] Preferably, the plasticizer includes one or a mixture of two or more of dimethyl phthalate, di-n-butyl phthalate, di-n-octyl phthalate, di(2-ethylhexyl) phthalate, and diisononyl phthalate.

[0011] Preferably, the epoxy resin is a bisphenol A type epoxy resin.

[0012] Preferably, the antioxidant comprises one or more combinations of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine, octadecyl 8-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and tris(2,4-di-tert-butylphenyl) phosphite.

[0013] By adopting the above technical solution, the raw materials of the epoxy hybrid polyurethane adhesive provided by the present invention are obtained by compounding conventional isocyanate-terminated polyurethane prepolymers and epoxy-terminated modified polyurethane prepolymers. The epoxy-terminated modified polyurethane prepolymers are epoxy-terminated, which allows them to undergo a co-curing reaction with the epoxy resin in the system, thereby forming a denser interpenetrating network structure. This structure enhances the crosslinking density between molecular chains, thus improving the thermal stability and tensile strength of the adhesive.

[0014] On the other hand, the terminal epoxy groups have high reactivity and can react and bond with the terminal isocyanate polyurethane prepolymer. This not only has a chain extension effect but also improves the compatibility between epoxy resin and polyurethane prepolymer, improves the two-phase interface, reduces phase separation, and thus enhances the mechanical properties of the adhesive.

[0015] Furthermore, the epoxy-modified polyurethane prepolymer of this invention is grafted with polysiloxane segments and secondary amine functional segments. The polysiloxane segments contain a large number of hydrophobic groups, which can accumulate on the adhesive surface, forming a hydrophobic barrier that effectively blocks the penetration of water molecules, thereby improving the adhesive's resistance to damp heat. Moreover, due to the high bond energy of the silicon-oxygen bonds in the polysiloxane segments, they are not easily broken at high temperatures, thus delaying the thermal decomposition process of the material and improving the thermal stability of the adhesive. Simultaneously, the flexibility of the polysiloxane segments helps absorb external stress, improving the toughness of the adhesive while maintaining high tensile strength, and enhancing the mechanical properties of the adhesive.

[0016] The introduction of secondary amine functional segments not only promotes ring-opening reactions between epoxy groups, thereby enhancing the cross-linking network density between molecular chains and improving the thermal decomposition temperature and thermal stability of the adhesive; but also, because the secondary amine functional segments themselves do not contain strong hydrophilic groups, they can effectively reduce the penetration and accumulation of moisture in the adhesive layer, thus helping to improve the adhesive's resistance to damp heat.

[0017] The introduction of secondary amine functional segments can also help extend the polyurethane molecular chain, acting as a chain extender. This, in turn, increases the crosslinking density and introduces a rigid-flexible synergistic structure, improving the molecular weight and degree of crosslinking of the adhesive during the crosslinking and curing process, thereby enhancing the adhesive's thermal stability and tensile strength. Furthermore, compared to other hydrophilic chain extenders, it does not contain strongly hydrophilic groups, resulting in reduced water absorption of the adhesive. Even in humid environments, it maintains good adhesion and durability, preventing the rapid development of thermal oxidation reactions.

[0018] The epoxy hybrid polyurethane adhesive provided by this invention also contains bifunctional POSS (cage-type polysilsesquioxane), which inherently possesses excellent thermal stability. During the crosslinking and curing process of the adhesive, it can act as a physical crosslinking point, covalently bonding with the polar groups contained in the polyurethane prepolymer and epoxy resin, increasing the crosslinking density, hindering the thermal motion of molecular chains, thereby delaying the thermal decomposition process and improving thermal stability. The hydrophobic inorganic core of the bifunctional POSS can also prevent water molecules from penetrating into the adhesive layer, further reducing the water absorption rate of the adhesive in conjunction with the polysiloxane segments contained in the epoxy-modified polyurethane prepolymer. The rigid cage-like structure of the bifunctional POSS can also work in conjunction with inorganic fillers to play a certain nano-reinforcing role in the adhesive. It has strong interfacial interactions with the polyurethane and epoxy resin segments, which can effectively transfer stress and improve the tensile strength of the adhesive.

[0019] Preferably, the raw materials for the epoxy-terminated modified polyurethane prepolymer include toluene diisocyanate, hydroxyl-terminated polydimethyl silicone oil, secondary amine functional monomers, and end-capping agents in a molar ratio of 1:(0.7-0.9):(0.1-0.3):(1-1.05).

[0020] Preferably, the raw materials for the secondary amine functional monomer include isophorone diamine and propylene carbonate in a mass ratio of 1:(1.2-1.4).

[0021] Preferably, the capping agent comprises one or more combinations of ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, glycidyl methacrylate, trimethylolpropane diglycidyl ether, and pentaerythritol diglycidyl ether.

[0022] Preferably, the epoxy-terminated modified polyurethane prepolymer is prepared according to the following method: Under a nitrogen atmosphere, isophorone diamine and propylene carbonate are mixed evenly, the temperature is raised to 110-120°C, and the reaction is stirred for 8-10 hours. Finally, the secondary amine functional monomer is obtained by vacuum distillation. Pretreated hydroxyl-terminated polydimethyl silicone oil was obtained by vacuum dehydration of hydroxyl-terminated polydimethyl silicone oil at 85-95°C for 1-2 hours. Toluene diisocyanate and catalyst are added to xylene and stirred until homogeneous. Then, secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil are added. The temperature is adjusted to 40–50°C and mixed until homogeneous. The temperature is then increased to 70–80°C and stirred for 2–4 hours. Subsequently, the temperature is lowered to 45–50°C, a capping agent is added, and the mixture is stirred until homogeneous. The temperature is then increased to 70–75°C, a catalyst is added, and the mixture is stirred for another 2–4 hours to obtain the final product.

[0023] Preferably, the catalyst comprises one or more combinations of stannous octoate, dibutyltin dilaurate, dibutyltin, dibutyltin diacetate, and dioctyltin.

[0024] By employing the above technical solution, isophorone diamine and propylene carbonate are first reacted to open the cyclic carbonate ring, generating a urethane structure containing hydroxyl groups, thus obtaining a bifunctional monomer with hydroxyl and secondary amine groups. The hydroxyl groups participate in the subsequent synthesis of the polyurethane prepolymer. The hydroxyl-terminated polydimethyl silicone oil is first subjected to vacuum dehydration treatment to remove the water adsorbed on it, preventing water molecules from reacting with the subsequent toluene diisocyanate, thereby ensuring the activity of the hydroxyl groups and their participation in the subsequent synthesis of the polyurethane prepolymer.

[0025] Then, through the reaction between the isocyanate groups and hydroxyl groups in toluene diisocyanate, a polyurethane prepolymer is gradually formed. The secondary amine groups, due to steric hindrance caused by isophorone diamine as a raw material, do not participate in the reaction. Subsequently, it reacts with a capping agent, where the active hydrogen in the capping agent reacts with the isocyanate groups at the ends of the prepolymer, introducing epoxy groups into the chain ends, resulting in an epoxy-terminated polyurethane prepolymer.

[0026] Introducing end-epoxy modified polyurethane prepolymers into epoxy hybrid polyurethane adhesives can, on the one hand, improve the thermal stability and hydrophobicity of the material by utilizing the grafted polysiloxane segments, enhance the resistance to damp heat, and on the other hand, increase the crosslinking density between the prepolymer and the epoxy resin, forming a denser crosslinking network, inhibiting the thermal movement of the chain segments, and also help to enhance the tensile strength of the adhesive.

[0027] Preferably, the bifunctional POSS is an epoxy-hydroxy bifunctional POSS.

[0028] More preferably, the epoxy-hydroxy bifunctional POSS is prepared according to the following method: An aminosilane coupling agent, chloropropanol, and triethylamine were added to toluene, mixed thoroughly, and then the temperature was raised to 50–55°C. The mixture was stirred and reacted for 4–5 hours. The hydroxyl precursor was then obtained by filtration and distillation. A hydroxyl precursor and an epoxy silane coupling agent are added to an alcohol solvent, mixed thoroughly, and then deionized water and an acidic catalyst are added. The mixture is stirred at room temperature for 6–8 h, then the temperature is raised to 70–80 °C and refluxed for 2–3 h. Finally, the mixture is obtained by vacuum distillation.

[0029] More preferably, the aminosilane coupling agent includes either γ-aminopropyltriethoxysilane or γ-aminopropyltrimethoxysilane; the mass ratio of the aminosilane coupling agent, chloropropanol and triethylamine is 1:(0.5-0.55):(0.55-0.6).

[0030] More preferably, the mass ratio of the hydroxyl precursor to the epoxy silane coupling agent is (0.2-0.3):(0.7-0.8).

[0031] More preferably, the epoxy silane coupling agent includes either γ-glycidoxypropyltrimethoxysilane or γ-glycidoxypropyltriethoxysilane.

[0032] More preferably, the acidic catalyst includes any one of hydrochloric acid, sulfuric acid, and trifluoromethanesulfonic acid.

[0033] By adopting the above technical solution, the amino groups contained in the aminosilane coupling agent undergo a nucleophilic substitution reaction with the chloride ions in chloropropanol to generate a hydroxyl precursor. Triethylamine acts as an acid-binding agent to absorb the byproducts generated in the reaction. Then, in an alcohol solvent, the hydroxyl precursor and the epoxysilane coupling agent are mixed and undergo a hydrolysis-condensation reaction under the action of an acidic catalyst and water to form a silicon-oxygen-silicon framework, gradually constructing a POSS cage structure. Then, the temperature is increased for reflux reaction to promote complete condensation and obtain an epoxy-hydroxyl bifunctional POSS.

[0034] In addition to its high thermal stability and ability to act as a rigid nanofiller to improve tensile strength, the epoxy-hydroxyl bifunctional POSS obtained has the added epoxy groups that help it disperse evenly in the system. Furthermore, it can synergistically react with the hydroxyl groups and residual isocyanate groups in the prepolymer, making the bifunctional POSS a bridge node in the crosslinking network. This enhances the integrity of the adhesive's crosslinking network, which not only improves thermal stability and resistance to damp heat but also enhances the tensile strength of the adhesive.

[0035] Secondly, the present invention provides a method for preparing an epoxy hybrid polyurethane adhesive, which includes the following process steps: The polyurethane prepolymer and epoxy resin are preheated and mixed evenly at 50-60°C. Then, plasticizer, antioxidant, inorganic filler and bifunctional POSS are added in sequence, and the mixture is stirred and dispersed to obtain the final product.

[0036] The beneficial effects of this invention are: 1. In the epoxy hybrid polyurethane adhesive provided by this invention, the polyurethane prepolymer is obtained by combining an isocyanate-terminated polyurethane prepolymer and an epoxy-modified polyurethane prepolymer. The epoxy-modified polyurethane prepolymer is epoxy-terminated, which not only forms a denser interpenetrating network structure but also improves the compatibility between the epoxy resin and the polyurethane prepolymer, improves the two-phase interface, and reduces phase separation. Furthermore, the epoxy-modified polyurethane prepolymer of this invention is grafted with polysiloxane segments and secondary amine functional segments. The polysiloxane segments can effectively block the penetration of water molecules and delay the thermal decomposition process of the material; the secondary amine functional segments contain secondary amine groups that can enhance the crosslinking network density between molecular chains and act as chain extenders, helping to extend the polyurethane molecular chains, ultimately promoting the obtaining of an epoxy hybrid polyurethane adhesive with high thermal stability, good resistance to damp heat, and high tensile strength.

[0037] 2. The epoxy hybrid polyurethane adhesive of this invention also contains a bifunctional POSS, which inherently possesses excellent thermal stability and can also serve as a rigid nanofiller, significantly improving the thermal stability and tensile strength of the adhesive. Furthermore, it can synergistically work with polysiloxane segments to block water molecules from penetrating into the adhesive layer, thus improving resistance to damp heat. Moreover, the bifunctional POSS is an epoxy-hydroxy bifunctional POSS; the introduced epoxy groups promote uniform dispersion and also act as bonding sites, enhancing the integrity of the adhesive's crosslinking network, further improving the adhesive's thermal stability and mechanical properties. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0039] Preparation Example 1

[0040] Preparation Example 1-1: An epoxy-terminated modified polyurethane prepolymer was prepared according to the following method: Under a nitrogen atmosphere, 10g of isophorone diamine and 13g of propylene carbonate were mixed evenly, the temperature was raised to 120℃, and the reaction was stirred for 8 hours. Finally, the secondary amine functional monomer was obtained by vacuum distillation. Pretreated hydroxyl-terminated polydimethyl silicone oil (viscosity 1000 mPa·s) was obtained by vacuum dehydration at 90°C for 1 h. Toluene diisocyanate and 1 wt% dibutyltin dilaurate were added to xylene and stirred until homogeneous. Then, the secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil obtained above were added, wherein the molar ratio of toluene diisocyanate, secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil was 1:0.2:0.8. The temperature was adjusted to 45°C and mixed evenly. The temperature was then increased to 75°C and stirred for 4 hours. Subsequently, the temperature was lowered to 45°C and ethylene glycol diglycidyl ether, the end-capping agent, was added, wherein the molar ratio of toluene diisocyanate and ethylene glycol diglycidyl ether was 1:1. After mixing, the temperature was increased to 70°C and 0.5 wt% dibutyltin dilaurate was added. The reaction was continued for 2-4 hours to obtain the final product.

[0041] Preparation Examples 1-2: An epoxy-terminated modified polyurethane prepolymer was prepared according to the following method: Under a nitrogen atmosphere, 10g of isophorone diamine and 12g of propylene carbonate were mixed evenly, the temperature was raised to 120℃, and the reaction was stirred for 8 hours. Finally, the secondary amine functional monomer was obtained by vacuum distillation. Pretreated hydroxyl-terminated polydimethyl silicone oil (viscosity 1000 mPa·s) was obtained by vacuum dehydration at 90°C for 1 h. Toluene diisocyanate and 1 wt% dibutyltin dilaurate were added to xylene and stirred until homogeneous. Then, the secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil obtained above were added, wherein the molar ratio of toluene diisocyanate, secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil was 1:0.3:0.7. The temperature was adjusted to 45°C, and after homogeneous mixing, the temperature was increased to 75°C and stirred for 4 hours. Subsequently, the temperature was lowered to 45°C, and the end-capping agent ethylene glycol diglycidyl ether was added, wherein the molar ratio of toluene diisocyanate and ethylene glycol diglycidyl ether was 1:1.05. After mixing, the temperature was increased to 70°C, and 0.5 wt% dibutyltin dilaurate was added. The reaction was continued for 2-4 hours to obtain the final product.

[0042] Preparation Examples 1-3: An epoxy-terminated modified polyurethane prepolymer was prepared according to the following method: Under a nitrogen atmosphere, 10g of isophorone diamine and 14g of propylene carbonate were mixed evenly, the temperature was raised to 120℃, and the reaction was stirred for 8 hours. Finally, the secondary amine functional monomer was obtained by vacuum distillation. Pretreated hydroxyl-terminated polydimethyl silicone oil (viscosity 1000 mPa·s) was obtained by vacuum dehydration at 90°C for 1 h. Toluene diisocyanate and 1 wt% dibutyltin dilaurate were added to xylene and stirred until homogeneous. Then, the secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil obtained above were added, wherein the molar ratio of toluene diisocyanate, secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil was 1:0.1:0.9. The temperature was adjusted to 45°C, and after homogeneous mixing, the temperature was increased to 75°C and stirred for 4 hours. Subsequently, the temperature was lowered to 45°C, and the end-capping agent ethylene glycol diglycidyl ether was added, wherein the molar ratio of toluene diisocyanate and ethylene glycol diglycidyl ether was 1:1. After mixing, the temperature was increased to 70°C, and 0.5 wt% dibutyltin dilaurate was added. The reaction was continued for 2-4 hours to obtain the final product.

[0043] Preparation Examples 1-4: A modified polyurethane prepolymer was prepared according to the following method: Under a nitrogen atmosphere, 10g of isophorone diamine and 13g of propylene carbonate were mixed evenly, the temperature was raised to 120℃, and the reaction was stirred for 8 hours. Finally, the secondary amine functional monomer was obtained by vacuum distillation. Pretreated hydroxyl-terminated polydimethyl silicone oil (viscosity 1000 mPa·s) was obtained by vacuum dehydration at 90°C for 1 h. Toluene diisocyanate and 1 wt% dibutyltin dilaurate were added to xylene and stirred until homogeneous. Then, the secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil obtained above were added. The molar ratio of toluene diisocyanate, secondary amine functional monomer and pretreated hydroxyl-terminated polydimethyl silicone oil was 1:0.2:0.8. The temperature was adjusted to 45°C and mixed until homogeneous. Then, the temperature was increased to 75°C and stirred for 4 hours to obtain the final product.

[0044] Preparation Examples 1-5: A modified polyurethane prepolymer, differing from Preparation Example 1-1 only in that the molar ratio of toluene diisocyanate, secondary amine functional monomer, and pretreated hydroxyl-terminated polydimethyl silicone oil is 1:0.4:0.6.

[0045] Preparation Examples 1-6: An epoxy-terminated modified polyurethane prepolymer was prepared according to the following method: Pretreated hydroxyl-terminated polydimethyl silicone oil (viscosity 1000 mPa·s) was obtained by vacuum dehydration at 90°C for 1 h. Toluene diisocyanate and 1 wt% dibutyltin dilaurate were added to xylene and stirred until homogeneous. Then, pretreated hydroxyl-terminated polydimethyl silicone oil was added, with a molar ratio of toluene diisocyanate to pretreated hydroxyl-terminated polydimethyl silicone oil of 1:1. The temperature was adjusted to 45°C, and after homogeneous mixing, the temperature was increased to 75°C and stirred for 4 hours. Subsequently, the temperature was lowered to 45°C, and ethylene glycol diglycidyl ether, a capping agent, was added, with a molar ratio of toluene diisocyanate to ethylene glycol diglycidyl ether of 1:1. After mixing, the temperature was increased to 70°C, and 0.5 wt% dibutyltin dilaurate was added. The reaction was continued for 2–4 hours to obtain the final product.

[0046] Preparation Examples 1-7: An epoxy-terminated modified polyurethane prepolymer was prepared according to the following method: Under a nitrogen atmosphere, 10g of isophorone diamine and 13g of propylene carbonate were mixed evenly, the temperature was raised to 120℃, and the reaction was stirred for 8 hours. Finally, the secondary amine functional monomer was obtained by vacuum distillation. Toluene diisocyanate and 1 wt% dibutyltin dilaurate were added to xylene and stirred until homogeneous. Then, the secondary amine functional monomer and ethylene glycol obtained above were added, wherein the molar ratio of toluene diisocyanate, secondary amine functional monomer and ethylene glycol was 1:0.2:0.8. The temperature was adjusted to 45°C, and after homogeneous mixing, the temperature was increased to 75°C and stirred for 4 hours. Subsequently, the temperature was lowered to 45°C, and the end-capping agent ethylene glycol diglycidyl ether was added, wherein the molar ratio of toluene diisocyanate and ethylene glycol diglycidyl ether was 1:1. After mixing, the temperature was increased to 70°C, and 0.5 wt% dibutyltin dilaurate was added. The reaction was continued for 2-4 hours to obtain the final product.

[0047] Preparation Example 2

[0048] Preparation Example 2-1: A bifunctional POSS was prepared according to the following method: 10g of γ-aminopropyltriethoxysilane, 5.5g of chloropropanol and 6g of triethylamine were added to toluene, mixed evenly, and the temperature was raised to 55℃. The mixture was stirred and reacted for 4h. The hydroxyl precursor was then obtained by filtration and distillation. Add 2g of the hydroxyl precursor obtained above and 8g of γ-glycidyl etheroxypropyltrimethoxysilane to methanol, mix well, then add 7.5g of deionized water and 7.8g of concentrated hydrochloric acid as an acidic catalyst. Stir the reaction at room temperature for 8 hours, then raise the temperature to 80℃ and reflux for 2 hours. Finally, obtain the product by vacuum distillation.

[0049] Preparation Example 2-2, a bifunctional POSS, differs from Preparation Example 2-1 only in that the amount of hydroxyl precursor added is 3g and the amount of γ-glycidoxypropyltrimethoxysilane added is 7g.

[0050] Preparation Examples 2-3: A functional POSS was prepared according to the following method: 10g of γ-aminopropyltriethoxysilane, 5.5g of chloropropanol and 6g of triethylamine were added to toluene, mixed evenly, and the temperature was raised to 55℃. The mixture was stirred and reacted for 4h. The hydroxyl precursor was then obtained by filtration and distillation. Add 10g of the hydroxyl precursor obtained above to methanol, mix well, then add 7.5g of deionized water and 7.8g of concentrated hydrochloric acid as an acidic catalyst. Stir the reaction at room temperature for 8 hours, then raise the temperature to 80℃ and reflux for 2 hours. Finally, distill under reduced pressure to obtain the product.

[0051] Preparation Examples 2-4: A functional POSS was prepared according to the following method: Add 10g of γ-glycidyl etheroxypropyltrimethoxysilane to methanol, mix well, then add 7.5g of deionized water and 7.8g of concentrated hydrochloric acid as an acidic catalyst. Stir the reaction at room temperature for 8 hours, then raise the temperature to 80℃ and reflux for 2 hours. Finally, distill under reduced pressure to obtain the final product.

[0052] Example

[0053] Example 1: An epoxy hybrid polyurethane adhesive was prepared according to the following method: 23 parts of polyurethane prepolymer and 12 parts of bisphenol A type epoxy resin were preheated at 55°C and mixed evenly. The polyurethane prepolymer included 15 parts of isocyanate-terminated polyurethane prepolymer and 8 parts of epoxy-terminated modified polyurethane prepolymer prepared in Preparation Example 1-1. Then, add 12 parts of dimethyl phthalate, 1 part of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate, 35 parts of montmorillonite, and 3 parts of the bifunctional POSS prepared in Preparation Example 2-1 in sequence, and continue stirring to disperse to obtain the final product.

[0054] Examples 2 and 3 describe an epoxy hybrid polyurethane adhesive, differing from Example 1 only in that the raw material ratios were adjusted, as shown in Table 1. Table 1. Formulation table for Examples 1 to 3

[0055] In both Examples 2 and 3, the epoxy-terminated polyurethane prepolymer prepared in Example 1, the bifunctional POSS prepared in Example 2-1, and the antioxidant pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)phenylpropionate were used.

[0056] Example 4: An epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the epoxy-modified polyurethane prepolymer prepared in Example 1-2 is used to replace the epoxy-modified polyurethane prepolymer prepared in Example 1-1.

[0057] Example 5: An epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the epoxy-modified polyurethane prepolymer prepared in Examples 1-3 is used to replace the epoxy-modified polyurethane prepolymer prepared in Example 1-1.

[0058] Example 6: An epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the bifunctional POSS prepared in Preparation Example 2-2 is used to replace the bifunctional POSS prepared in Preparation Example 2-1.

[0059] Example 7: An epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the epoxy-modified polyurethane prepolymer prepared in Examples 1-5 is used to replace the epoxy-modified polyurethane prepolymer prepared in Example 1-1.

[0060] Comparative Example

[0061] Comparative Example 1, an epoxy hybrid polyurethane adhesive, differs from Example 1 only in that the polyurethane prepolymer comprises 21 parts of isocyanate-terminated polyurethane prepolymer and 2 parts of epoxy-terminated modified polyurethane prepolymer prepared in Preparation Example 1-1.

[0062] Comparative Example 2, an epoxy hybrid polyurethane adhesive, differs from Example 1 only in that the polyurethane prepolymer comprises 8 parts of isocyanate-terminated polyurethane prepolymer and 15 parts of epoxy-terminated modified polyurethane prepolymer prepared in Preparation Example 1-1.

[0063] Comparative Example 3 is an epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the modified polyurethane prepolymer prepared in Preparation Examples 1-4 is used to replace the end-epoxy modified polyurethane prepolymer prepared in Preparation Example 1-1.

[0064] Comparative Example 4, an epoxy hybrid polyurethane adhesive, differs from Example 1 only in that an equal amount of the epoxy-modified polyurethane prepolymer prepared in Examples 1-6 is used to replace the epoxy-modified polyurethane prepolymer prepared in Example 1-1.

[0065] Comparative Example 5 is an epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the epoxy-modified polyurethane prepolymer prepared in Examples 1-7 is used to replace the epoxy-modified polyurethane prepolymer prepared in Example 1-1.

[0066] Comparative Example 6, an epoxy hybrid polyurethane adhesive, differs from Example 1 only in that the polyurethane prepolymer comprises 23 parts of isocyanate-terminated polyurethane prepolymer.

[0067] Comparative Example 7 is an epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the functional POSS prepared in Preparation Examples 2-3 is used to replace the bifunctional POSS prepared in Preparation Example 2-1.

[0068] Comparative Example 8 is an epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that an equal amount of the functional POSS prepared in Preparation Examples 2-4 is used to replace the bifunctional POSS prepared in Preparation Example 2-1.

[0069] Comparative Example 9 is an epoxy hybrid polyurethane adhesive, which differs from Example 1 only in that the bifunctional POSS prepared in Preparation Example 2-1 is not added.

[0070] Performance testing

[0071] 1. Tensile strength test: According to the relevant records in GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", the tensile strength of the obtained epoxy hybrid polyurethane adhesive was tested, and the test results are shown in Table 2.

[0072] 2. Heat resistance test: The epoxy hybrid polyurethane adhesive obtained in the examples and comparative examples is mixed with ethylenediamine in an equal proportion to obtain a mixed adhesive. The mixed adhesive is injected into a 2mm thick aluminum foil mold, with a single injection amount of 35g to obtain a colloid sample block.

[0073] The sample was left to stand in a drying oven at 150℃ for 1000 hours. The tensile strength of the colloidal sample was tested before and after the heat treatment, and the retention rate of tensile strength was calculated. Meanwhile, the same colloidal sample was placed in a constant temperature and humidity chamber for 1000 hours, with the test temperature maintained at 85℃ and the test humidity at 85%. The tensile strength of the colloidal sample was tested before and after the damp heat treatment, and the retention rate of tensile strength was calculated. The retention rate of tensile strength is calculated as follows:

[0074] The results of the above experiments are shown in Table 3.

[0075] Table 2 Tensile strength test results

[0076] Table 3 Results of heat resistance test

[0077] Based on Tables 2 and 3, and in conjunction with Examples 1 and 7, it can be seen that the tensile strength of Example 7 and the tensile strength retention rate after heat treatment and damp heat treatment are lower than those of Example 1. This indicates that the thermal stability and damp heat resistance of Example 7 are lower than those of Example 1. The reason for this may be that the epoxy-modified polyurethane prepolymer in Example 7 has an excessive amount of secondary amine functional segments grafted onto it. An excessive amount of secondary amine groups will form a large amount of urethane with isocyanate groups, which will cause the crosslinking density of the prepolymer to increase sharply, thereby restricting the movement of molecular chains, greatly increasing brittleness, significantly decreasing tensile strength, and even decreasing thermal stability.

[0078] Based on Examples 1 and Comparative Examples 3 to 6, it can be seen that the tensile strength and the retention rate of tensile strength after heat treatment and humid heat treatment in Comparative Examples 3 to 6 are lower than those in Example 1. The reason may be that Comparative Example 3 did not use epoxy group end-capping, resulting in a decrease in crosslinking network density, thermal stability, and tensile strength. Comparative Example 4 did not have grafted secondary amine functional segments, resulting in a decrease in the elongation effect of polyurethane molecular chains, a decrease in crosslinking density, a decrease in durability, and a decrease in the binding effect with epoxy groups. Comparative Example 5 did not have grafted polysiloxane segments, resulting in a reduction in the hydrophobic barrier, a decrease in the water molecule penetration effect, and a decrease in humid heat resistance. In Comparative Example 6, the polyurethane prepolymer was not modified, resulting in a more significant decrease in performance.

[0079] Based on Examples 1 and Comparative Examples 7-9, it can be seen that the tensile strength and tensile strength retention rate after heat treatment and hydrothermal treatment of Comparative Examples 7-9 are lower than those of Example 1. This may be because the functional POSS in Comparative Example 7 contains only epoxy groups, and the functional POSS in Comparative Example 8 contains only hydroxyl groups. Therefore, the interaction between the functional groups and isocyanate groups is lacking, significantly reducing the number of bridging nodes in the crosslinking network, resulting in a decrease in the density of the crosslinking network and a decline in all properties. Comparative Example 9, which did not contain bifunctional POSS, showed a more significant performance decline, and its thermal stability also decreased considerably.

[0080] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An epoxy-hybridized polyurethane adhesive, characterized by, Raw materials including the following mass fractions: Polyurethane prepolymer 15-30 parts; Epoxy resin 5-20 parts; Inorganic filler 30-40 parts; Bifunctional POSS 1-5 parts; Plasticizer 10-15 parts; Antioxidant 0.1-2 parts; The polyurethane prepolymer comprises, in mass ratio, (10-20) of an isocyanate-terminated polyurethane prepolymer and (5-10) of an epoxy-modified polyurethane prepolymer; The epoxy-modified polyurethane prepolymer is grafted with polysiloxane segments and secondary amine functional segments.

2. The epoxy hybrid polyurethane adhesive according to claim 1, characterized in that, Raw materials of the epoxy-modified polyurethane prepolymer comprise, in molar ratio, toluene diisocyanate, hydroxyl-terminated polydimethylsiloxane, secondary amine functional monomer and end-capping agent at 1: (0.7-0.9): (0.1-0.3): (1-1.05).

3. The epoxy hybrid polyurethane adhesive according to claim 2, characterized in that, Raw materials of the secondary amine functional monomer comprise, in mass ratio, isophorone diamine and propylene carbonate at 1: (1.2-1.4).

4. The epoxy hybrid polyurethane adhesive according to claim 2, characterized in that, The end-capping agent comprises a combination of one or more of ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, glycidyl methacrylate, trimethylolpropane diglycidyl ether and pentaerythritol diglycidyl ether.

5. The epoxy hybrid polyurethane adhesive according to claim 2, wherein The epoxy-modified polyurethane prepolymer is prepared by the following method: Under a nitrogen atmosphere, isophorone diamine and propylene carbonate are mixed uniformly, the temperature is raised to 110-120°C, and stirring is performed for 8-10 hours, after which the secondary amine functional monomer is obtained by reduced pressure distillation; The hydroxyl-terminated polydimethylsiloxane is pre-processed by vacuum dehydration at 85-95°C for 1-2 hours; Toluene diisocyanate and a catalyst are added to xylene, stirred uniformly, and then the secondary amine functional monomer and the pre-processed hydroxyl-terminated polydimethylsiloxane are added, the temperature is adjusted to 40-50°C, and after mixing uniformly, the temperature is raised to 70-80°C and stirring is performed for 2-4 hours; then the temperature is lowered to 45-50°C, the end-capping agent is added, mixed, the temperature is raised to 70-75°C, a catalyst is added, and stirring is continued for 2-4 hours to obtain the epoxy-modified polyurethane prepolymer.

6. The epoxy hybrid polyurethane adhesive according to claim 5, characterized in that The catalyst comprises a combination of one or more of stannous octoate, dibutyltin dilaurate, dibutyltin, dibutyltin diacetate and dioctyltin.

7. The epoxy hybrid polyurethane adhesive of claim 1, wherein The bifunctional POSS is an epoxy-hydroxyl bifunctional POSS.

8. The epoxy hybrid polyurethane adhesive of claim 1, wherein The inorganic filler comprises a combination of one or more of montmorillonite, silica powder and talc powder.

9. The epoxy hybrid polyurethane adhesive of claim 1, wherein The plasticizer comprises dimethyl phthalate, di-n-butyl phthalate, di-n-octyl phthalate, di(2-ethyl)hexyl phthalate, diisononyl phthalate or a mixture of two or more thereof.

10. A method for preparing an epoxy hybrid polyurethane adhesive for obtaining the epoxy hybrid polyurethane adhesive according to any one of claims 1 to 9, characterized in that, The process comprises the following steps: The polyurethane prepolymer and the epoxy resin are preheated and mixed uniformly at 50-60°C, and then the plasticizer, the antioxidant, the inorganic filler and the bifunctional POSS are added in sequence, and stirring and dispersion are continued to obtain the product.

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