High-temperature-resistant and low-temperature-resistant polyurethane hot melt adhesive with high adhesive force and preparation method thereof

Abstract

The application discloses a high and low temperature resistant and high adhesive force polyurethane hot melt adhesive and a preparation method thereof, and relates to the technical field of hot melt adhesives. Components of the polyurethane hot melt adhesive include, by weight fraction, 50-60 parts of a composite soft segment polyol, 20-25 parts of a modified isocyanate component, 5-8 parts of a dynamic crosslinking chain extender, 4-7 parts of a functional component, and 0.08-0.25 parts of a catalyst. The functional component comprises nano aluminum nitride, a silane coupling agent, an ultraviolet absorber, an antioxidant, a polyamide wax thixotropic agent, hydroxyl fluorosilicone oil and poly(2-ethyl-2-oxazoline)-diamino end-capping. The polyurethane hot melt adhesive has the advantages of wide temperature resistance, high adhesive force and water resistance.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, and in particular to a high and low temperature resistant, high adhesion polyurethane hot melt adhesive and its preparation method. Background Technology

[0002] Polyurethane hot melt adhesives, as an environmentally friendly adhesive, are widely used in the automotive, electronics, and packaging industries. However, traditional polyurethane hot melt adhesives have significant shortcomings in terms of high and low temperature resistance and adhesion. At low temperatures, the flexibility of the adhesive molecular chains decreases, making them prone to brittleness and cracking, leading to delamination at the bonding interface. At high temperatures, the thermal motion of the molecular chains intensifies, reducing the stability of the cross-linked structure, resulting in softening, creep, and a significant decrease in bond strength. This makes it difficult to meet the requirements of wide-temperature applications such as automotive engine components and outdoor electronic devices.

[0003] To improve high and low temperature resistance, existing technologies often use a single type of polyol (such as pure polyether or pure polyester) as the soft segment. However, this results in a performance imbalance: pure polyether-based polyurethane hot melt adhesives have good low-temperature resistance but insufficient high-temperature resistance and mechanical strength; pure polyester-based products have improved high-temperature resistance but poor low-temperature toughness and are prone to brittleness. Meanwhile, some solutions enhance high-temperature resistance by adding inorganic fillers (such as calcium carbonate and silica), but uneven filler dispersion can lead to defects at the bonding interface, thus reducing adhesion. Adding large amounts of filler can also sacrifice application flowability. Commercially available polyurethane hot melt adhesives also struggle to simultaneously balance high and low temperature resistance with bond strength.

[0004] To address the aforementioned issues, patent document CN114736644B discloses a transparent edge-sealing adhesive and its preparation method. The raw materials for its preparation include the following components in parts by weight: 5-15 parts polyether polyol, 40-80 parts polyester polyol, 5-30 parts transparent polyurethane elastomer, 5-20 parts copolyester, 5-15 parts chain extender, 10-20 parts isocyanate, and 0.01-3 parts additives. The transparent edge-sealing adhesive prepared in this application is solvent-free, with a 100% solids content. This effectively avoids problems such as contamination caused by solvents while ensuring smooth adhesive application and effectively improving the problem of rapid shrinkage of crystalline polyester edge-sealing adhesives upon cooling. Furthermore, the transparent edge-sealing adhesive of this application does not exhibit stringing issues during edge-sealing application and does not create defects such as foreign matter clumps on the substrate. Moreover, it possesses certain no-clean properties, and can be used continuously for 72 hours at a continuous melting temperature of 120-160℃ without requiring cleaning of the adhesive pot. However, its waterproof performance, temperature resistance, and bonding strength still need further improvement. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a high-temperature resistant, high-adhesion polyurethane hot melt adhesive that combines wide temperature range tolerance, high adhesion and waterproofness, as well as its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a high and low temperature resistant, high adhesion polyurethane hot melt adhesive, comprising the following components by weight: 50-60 parts of composite soft segment polyol, 20-25 parts of modified isocyanate component, 5-8 parts of dynamic crosslinking chain extender, 4-7 parts of functional component, and 0.08-0.25 parts of catalyst; wherein the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent.

[0007] Preferably, the composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:(0.5-1).

[0008] Preferably, the polytetrahydrofuran ether diol is polytetrahydrofuran ether diol PTMG-2000; the polycaprolactone diol is polycaprolactone diol PCL-2000; and the hydroxyl-terminated polybutadiene is hydroxyl-terminated polybutadiene HTPB-2000.

[0009] Preferably, the modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of (2.5-3):0.5.

[0010] Preferably, the carbodiimide-modified MDI is Wanhua CDMDI-100L, with CAS number 25686-28-6.

[0011] Preferably, the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:(0.8-1.2).

[0012] Preferably, the mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is (1-3):(0.8-2):(0.3-1):(0.5-1.5):(0.4-0.8):(0.3-1):(0.5-1.5).

[0013] Preferably, the average particle size of the nano-aluminum nitride is 50-80 nm.

[0014] Preferably, the silane coupling agent is silane coupling agent KH560.

[0015] Preferably, the ultraviolet absorber is the light stabilizer UV-3808PP5.

[0016] Preferably, the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

[0017] Preferably, the polyamide wax thixotropic agent is polyamide wax NEW-0402E.

[0018] Preferably, the hydroxyl fluorosilicone oil has a number-average molecular weight of 1000-2000 and a hydroxyl value of 40-60 mgKOH / g.

[0019] Preferably, the number average molecular weight of the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is 1000-2000.

[0020] Preferably, the catalyst is a mixture of dibutyltin dilaurate and bismuth isooctanoate in a mass ratio of 1:(2-3).

[0021] Another object of the present invention is to provide a method for preparing the high and low temperature resistant, high adhesion polyurethane hot melt adhesive, comprising the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 120-130℃, and dehydrate under a vacuum of -0.1MPa for 2-3 hours; then cool to 65-70℃, turn on a high-speed disperser and stir at 1500-1800r / min for 30-40 minutes to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 600-800 r / min for 30 min at 70℃; then gradually increase the temperature to 85℃ at a rate of 5℃ / h, and maintain the temperature for 1.5-2 h; then add hexamethylene diisocyanate trimer, and continue the reaction at 90℃ for 1-1.5 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEO2-NH2 dropwise to the reactor at a rate of 1-1.5 mL / min. After the addition is complete, keep the temperature for 40-50 min; then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 65-70℃, add nano aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at a high speed of 1800-2000 r / min for 2-2.5 h. Step S5: Add the catalyst to the reactor and stir at 800-1000 r / min for 30-40 min; then, devolatilize at 80℃ and -0.09MPa vacuum for 30-40 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive.

[0022] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The high-temperature resistant and high-adhesion polyurethane hot melt adhesive disclosed in this invention breaks through the performance imbalance bottleneck caused by existing single polyether or polyester soft segments through the synergistic design of composite soft segment polyols. The ether bond structure of polytetrahydrofuran ether diol endows the molecular chain with excellent low-temperature flexibility, the ester bond regularity of polycaprolactone diol improves high-temperature stability and mechanical strength, and the unsaturated bond structure of hydroxyl-terminated polybutadiene further enhances the toughness and weather resistance of the system. When the three are compounded in a specific ratio, a synergistic effect of "low-temperature flexibility-high-temperature stability-overall strength" is formed, which enables the hot melt adhesive to maintain structural stability in a wide temperature range and solves the core pain points of low-temperature brittleness and high-temperature creep of traditional products.

[0023] (2) The high-temperature and low-temperature resistant, high-adhesion polyurethane hot melt adhesive disclosed in this invention achieves simultaneous improvement in adhesion and environmental resistance through the innovative combination of modified isocyanate components. The carbodiimide bonds introduced by the carbodiimide-modified MDI not only have excellent hydrolysis resistance but also reduce the crystallization rate of the system, avoiding stress concentration within the adhesive layer; the multifunctional structure of the hexamethylene diisocyanate trimer significantly increases the crosslinking density, enhancing the high-temperature creep resistance of the adhesive layer. When the two are compounded in a specific ratio, compared with the existing single isocyanate system, the interfacial bonding strength between the adhesive layer and substrates such as metals, plastics, and rubber is improved, while the resistance to damp heat aging is greatly optimized.

[0024] (3) The high-temperature resistant and high-adhesion polyurethane hot melt adhesive disclosed in this invention possesses a unique wide-temperature-range adaptability due to the multi-component composite design of the dynamic crosslinking chain extender, achieving dynamic adjustment of "rigidity-flexibility". 1,4-Butanediol provides basic crosslinking strength, and the dynamic disulfide bonds introduced by dicaprolactam disulfide can undergo reversible breakage and recombination when the temperature changes, relieving the internal stress of the molecular chain under wide temperature range and avoiding brittleness at low temperature and excessive softening at high temperature; the tertiary amine group of N-methyldiethanolamine enhances the polarity of the molecular chain and improves the interaction with the polar substrate. This dynamic crosslinking system enables the hot melt adhesive to maintain good flexibility at low temperature and has no obvious creep at high temperature, breaking through the technical limitations of existing static crosslinking systems that are difficult to balance high and low temperature performance.

[0025] (4) The high-temperature resistant and high-adhesion polyurethane hot melt adhesive disclosed in this invention solves the contradiction between "reinforcement and flowability, waterproofing and adhesion" in the prior art through the synergistic effect of functional components. Nano-aluminum nitride achieves uniform dispersion by virtue of its high specific surface area and surface modification with silane coupling agent, which not only improves the thermal conductivity and mechanical strength of the adhesive layer, but also avoids the interface defects caused by uneven dispersion of traditional inorganic fillers. The fluorocarbon chain structure of hydroxyl fluorosilicone oil gives the adhesive layer excellent waterproofing without affecting the adhesive layer's compatibility with the substrate. The polar segments of poly(2-ethyl-2-oxazoline)-diamino-terminated poly(2-ethyl-2-oxazoline) form a strong interaction with the active groups on the substrate surface, further strengthening the adhesion. The ultraviolet absorber and antioxidant work synergistically with the above components to improve the weather resistance of the adhesive layer and extend its outdoor service life. This functional system enables the hot melt adhesive to maintain excellent construction flowability while simultaneously improving adhesion strength, waterproofing and weather resistance, solving the technical problem in the prior art of sacrificing construction performance and reducing adhesion due to the addition of functional fillers to improve waterproofing.

[0026] (5) The high-temperature and low-temperature resistant, high-adhesion polyurethane hot melt adhesive disclosed in this invention ensures that all components react fully and disperse evenly through precise control of the preparation process. Vacuum dehydration and high-speed dispersion are combined to completely melt the polyamide wax thixotropic agent, avoiding the agglomeration of the thixotropic agent and affecting the smoothness of the adhesive layer; gradient heating and the addition of chain extenders are used to control the reaction rate, reduce side reactions, and ensure the uniformity of the prepolymer structure; high-temperature vacuum devolatilization and nitrogen protection processes remove bubbles and impurities from the system, improving the density of the adhesive layer. The final product not only significantly outperforms existing technologies in terms of wide temperature range tolerance, high adhesion, and water resistance, but also has good processing stability and storage stability, which can meet the use requirements of harsh scenarios such as automotive engine peripherals, outdoor electronic devices, and high-end packaging, filling the gap in existing polyurethane hot melt adhesives for high-requirement wide temperature range applications. Detailed Implementation

[0027] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. Example 1

[0028] A high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive comprises the following components by weight: 50 parts of composite soft segment polyol, 20 parts of modified isocyanate component, 5 parts of dynamic crosslinking chain extender, 4 parts of functional component, and 0.08 parts of catalyst; wherein the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent.

[0029] The composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:0.5; the polytetrahydrofuran ether diol is polytetrahydrofuran ether diol PTMG-2000; the polycaprolactone diol is polycaprolactone diol PCL-2000; the hydroxyl-terminated polybutadiene is hydroxyl-terminated polybutadiene HTPB-2000; the modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of 2.5:0.5; the carbodiimide-modified MDI is Wanhua CDMDI-100L, CAS number 25686-28-6; the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:0.8.

[0030] The mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is 1:0.8:0.3:0.5:0.4:0.3:0.5; the average particle size of the nano-aluminum nitride is 50 nm; the silane coupling agent is silane coupling agent KH560; and the ultraviolet absorber is light stabilizer UV. -3808PP5; the antioxidant is antioxidant 1010; the polyamide wax thixotropic agent is polyamide wax NEW-0402E; the hydroxyl fluorosilicone oil has a number-average molecular weight of 1000 and a hydroxyl value of 40 mg KOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number-average molecular weight of 1000; the catalyst is a mixture of dibutyltin dilaurate and bismuth isooctanoate in a mass ratio of 1:2.

[0031] A method for preparing the high and low temperature resistant, high adhesion polyurethane hot melt adhesive includes the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 120°C, and dehydrate for 2 hours under a vacuum of -0.1 MPa; then cool to 65°C, turn on a high-speed disperser and stir at 1500 r / min for 30 minutes to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 600 r / min for 30 min at 70 °C; then increase the temperature to 85 °C at a gradient rate of 5 °C / h and hold for 1.5 h; then add hexamethylene diisocyanate trimer and increase the temperature to 90 °C to continue the reaction for 1 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 to the reactor at a rate of 1 mL / min. After the addition is complete, keep the temperature for 40 min. Then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 65℃, add nano aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at 1800 r / min for 2 h. Step S5: Add the catalyst to the reactor and stir at 800 r / min for 30 min; then, devolve at 80℃ and -0.09 MPa vacuum for 30 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive. Example 2

[0032] A high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive comprises the following components by weight: 53 parts of composite soft segment polyol, 22 parts of modified isocyanate component, 6 parts of dynamic crosslinking chain extender, 5 parts of functional component, and 0.13 parts of catalyst; wherein the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent.

[0033] The composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:0.6; the polytetrahydrofuran ether diol is PTMG-2000; the polycaprolactone diol is PCL-2000; the hydroxyl-terminated polybutadiene is HTPB-2000; the modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of 2.6:0.5; the carbodiimide-modified MDI is Wanhua CDMDI-100L, CAS number 25686-28-6; the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:0.9.

[0034] The mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is 1.5:1.2:0.5:0.8:0.5:0.5:0.8; the average particle size of the nano-aluminum nitride is 60 nm; the silane coupling agent is silane coupling agent KH560; and the ultraviolet absorber is light stabilizer U. V-3808PP5; the antioxidant is antioxidant 168; the polyamide wax thixotropic agent is polyamide wax NEW-0402E; the hydroxyl fluorosilicone oil has a number-average molecular weight of 1300 and a hydroxyl value of 45 mgKOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number-average molecular weight of 1200; the catalyst is a mixture of dibutyltin dilaurate and bismuth isooctanoate in a mass ratio of 1:2.3.

[0035] A method for preparing the high and low temperature resistant, high adhesion polyurethane hot melt adhesive includes the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 123℃, and dehydrate for 2.3h under a vacuum of -0.1MPa; then cool to 67℃, turn on a high-speed disperser and stir at 1600r / min for 33min to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 650 r / min for 30 min at 70 °C; then increase the temperature to 85 °C at a gradient rate of 5 °C / h and hold for 1.7 h; then add hexamethylene diisocyanate trimer, and continue the reaction at 90 °C for 1.2 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 dropwise into the reactor at a rate of 1.2 mL / min. After the addition is complete, keep the temperature for 43 min. Then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 67°C, add nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at a high speed of 1850 r / min for 2.2 h; Step S5: Add the catalyst to the reactor and stir at 850 r / min for 33 min; then, devolve at 80℃ and -0.09 MPa vacuum for 33 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive. Example 3

[0036] A high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive comprises the following components by weight: 55 parts of composite soft segment polyol, 23 parts of modified isocyanate component, 6.5 parts of dynamic crosslinking chain extender, 5.5 parts of functional component, and 0.16 parts of catalyst; wherein the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent.

[0037] The composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:0.7; the polytetrahydrofuran ether diol is polytetrahydrofuran ether diol PTMG-2000; the polycaprolactone diol is polycaprolactone diol PCL-2000; the hydroxyl-terminated polybutadiene is hydroxyl-terminated polybutadiene HTPB-2000; the modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of 2.8:0.5; the carbodiimide-modified MDI is Wanhua CDMDI-100L, CAS number 25686-28-6; the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:1.

[0038] The mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is 2:1.4:0.7:1:0.6:0.7:1; the average particle size of the nano-aluminum nitride is 65 nm; the silane coupling agent is silane coupling agent KH560; and the ultraviolet absorber is light stabilizer UV-38. 08PP5; the antioxidant is antioxidant 1010; the polyamide wax thixotropic agent is polyamide wax NEW-0402E; the hydroxyl fluorosilicone oil has a number-average molecular weight of 1500 and a hydroxyl value of 50 mg KOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number-average molecular weight of 1500; the catalyst is a mixture of dibutyltin dilaurate and bismuth isooctanoate in a mass ratio of 1:2.5.

[0039] A method for preparing the high and low temperature resistant, high adhesion polyurethane hot melt adhesive includes the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 125℃, and dehydrate for 2.5h under a vacuum of -0.1MPa; then cool to 68℃, turn on a high-speed disperser and stir at 1650r / min for 35min to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 700 r / min for 30 min at 70 °C; then gradually increase the temperature to 85 °C at a rate of 5 °C / h, and maintain the temperature for 1.8 h; then add hexamethylene diisocyanate trimer, and continue the reaction at 90 °C for 1.3 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 dropwise into the reactor at a rate of 1.3 mL / min. After the addition is complete, keep the temperature for 45 min. Then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 68℃, add nano aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at a high speed of 1900 r / min for 2.3 h; Step S5: Add the catalyst to the reactor and stir at 900 r / min for 35 min; then, devolve at 80℃ and -0.09 MPa vacuum for 35 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive. Example 4

[0040] A high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive comprises the following components by weight: 58 parts of composite soft segment polyol, 24 parts of modified isocyanate component, 7.5 parts of dynamic crosslinking chain extender, 6.5 parts of functional component, and 0.23 parts of catalyst; wherein the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent.

[0041] The composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:0.9; the polytetrahydrofuran ether diol is PTMG-2000; the polycaprolactone diol is PCL-2000; the hydroxyl-terminated polybutadiene is HTPB-2000; the modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of 2.9:0.5; the carbodiimide-modified MDI is Wanhua CDMDI-100L, CAS number 25686-28-6; the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:1.1.

[0042] The mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is 2.5:1.8:0.9:1.3:0.75:0.9:1.3; the average particle size of the nano-aluminum nitride is 75 nm; the silane coupling agent is silane coupling agent KH560; and the ultraviolet absorber is light stabilizer UV-3808PP5. The antioxidant is composed of antioxidant 1010 and antioxidant 168 mixed in a mass ratio of 3:5; the polyamide wax thixotropic agent is polyamide wax NEW-0402E; the hydroxyl fluorosilicone oil has a number-average molecular weight of 1900 and a hydroxyl value of 55 mgKOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number-average molecular weight of 1900; the catalyst is composed of dibutyltin dilaurate and bismuth isooctanoate mixed in a mass ratio of 1:2.8.

[0043] A method for preparing the high and low temperature resistant, high adhesion polyurethane hot melt adhesive includes the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 128℃, and dehydrate for 2.8h under a vacuum of -0.1MPa; then cool to 69℃, turn on a high-speed disperser and stir at 1750r / min for 38min to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 750 r / min for 30 min at 70 °C; then gradually increase the temperature to 85 °C at a rate of 5 °C / h, and maintain the temperature for 1.9 h; then add hexamethylene diisocyanate trimer, and continue the reaction at 90 °C for 1.4 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 dropwise to the reactor at a rate of 1.4 mL / min. After the addition is complete, keep the temperature for 48 min. Then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 69°C, add nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at a high speed of 1950 r / min for 2.4 h; Step S5: Add the catalyst to the reactor and stir at 950 r / min for 38 min; then, devolve at 80℃ and -0.09 MPa vacuum for 38 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive. Example 5

[0044] A high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive comprises the following components by weight: 60 parts of composite soft segment polyol, 25 parts of modified isocyanate component, 8 parts of dynamic crosslinking chain extender, 7 parts of functional component, and 0.25 parts of catalyst; wherein the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent.

[0045] The composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:1; the polytetrahydrofuran ether diol is PTMG-2000; the polycaprolactone diol is PCL-2000; the hydroxyl-terminated polybutadiene is HTPB-2000; the modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of 3:0.5; the carbodiimide-modified MDI is Wanhua CDMDI-100L, CAS number 25686-28-6; the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:1.2.

[0046] The mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is 3:2:1:1.5:0.8:1:1.5; the average particle size of the nano-aluminum nitride is 80 nm; the silane coupling agent is silane coupling agent KH560; and the ultraviolet absorber is light stabilizer UV-38. 08PP5; the antioxidant is antioxidant 1010; the polyamide wax thixotropic agent is polyamide wax NEW-0402E; the hydroxyl fluorosilicone oil has a number-average molecular weight of 2000 and a hydroxyl value of 60 mgKOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number-average molecular weight of 2000; the catalyst is a mixture of dibutyltin dilaurate and bismuth isooctanoate in a mass ratio of 1:3.

[0047] A method for preparing the high and low temperature resistant, high adhesion polyurethane hot melt adhesive includes the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 130℃, and dehydrate for 3 hours under a vacuum of -0.1MPa; then cool to 70℃, turn on a high-speed disperser and stir at 1800r / min for 40 minutes to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 800 r / min for 30 min at 70 °C; then increase the temperature to 85 °C at a gradient rate of 5 °C / h and hold for 2 h; then add hexamethylene diisocyanate trimer, and continue the reaction at 90 °C for 1.5 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 dropwise into the reactor at a rate of 1.5 mL / min. After the addition is complete, keep the temperature for 50 min. Then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 70℃, add nano aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at a high speed of 2000 r / min for 2.5 h; Step S5: Add the catalyst to the reactor and stir at 1000 r / min for 40 min; then, devolve at 80℃ and -0.09 MPa vacuum for 40 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive.

[0048] Comparative Example 1 This example provides a high and low temperature resistant, high adhesion polyurethane hot melt adhesive and its preparation method, which is basically the same as Example 1, except that hydroxyl fluorosilicone oil and poly(2-ethyl-2-oxazoline)-diamino end-capping are not added.

[0049] Comparative Example 2 This example provides a high and low temperature resistant, high adhesion polyurethane hot melt adhesive and its preparation method, which is basically the same as that in Example 1, except that an equal amount of polytetrahydrofuran ether diol is used instead of hydroxyl-terminated polybutadiene.

[0050] To further illustrate the beneficial technical effects of the high and low temperature resistant, high adhesion polyurethane hot melt adhesives involved in the various embodiments of the present invention, relevant performance tests were conducted on the products of Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1, and the test methods are as follows: (1) Tensile shear strength: The test was conducted in accordance with GB / T 7124-2008. The substrate was 6061 aluminum alloy. Curing conditions: The hot melt adhesive was melted in a hot melt glue gun at 160℃ and evenly coated on the bonding surface of the substrate. The coating thickness was controlled to be 0.2mm. The other substrate was aligned and overlapped, and a pressure of 0.5MPa was applied. The substrate was cured for 72h at 25℃ and 50%RH.

[0051] (2) High and low temperature resistance: -40℃ (4h) → 25℃ (2h) → 150℃ (4h) is 1 cycle, and a total of 15 cycles are performed. After the cycle, the tensile shear strength is tested according to the method in (1), and the retention rate is calculated. The larger the value, the better the high and low temperature resistance.

[0052] (3) Waterproofing: Soak the cured adhesive in 50°C water for 12 hours. After 12 hours, take it out and observe. If there is no change in the adhesive, the waterproofing performance of the polyurethane hot melt adhesive is recorded as "qualified"; if the adhesive absorbs water and swells, the waterproofing performance of the polyurethane hot melt adhesive is recorded as "unqualified".

[0053] Table 1. Test results of high and low temperature resistant, high adhesion polyurethane hot melt adhesive properties. unit MPa % — Example 1 16.2 93.5 qualified Example 2 17.0 94.8 qualified Example 3 17.6 95.2 qualified Example 4 18.1 96.1 qualified Example 5 18.5 96.8 qualified Comparative Example 1 10.5 83.0 Unqualified Comparative Example 2 13.8 76.3 qualified As shown in Table 1, the high and low temperature resistant and high adhesion polyurethane hot melt adhesives of Examples 1-5 are superior to those of Comparative Examples 1-2 in terms of performance. Specifically, the tensile shear strength gradually increases from 16.2 MPa to 18.5 MPa, the high and low temperature resistance (strength retention rate) remains stable at 93.5%-96.8%, and the waterproof performance is satisfactory. In contrast, Comparative Example 1, lacking hydroxyl fluorosilicone oil and poly(2-ethyl-2-oxazoline)-diamino end-capping, has a tensile shear strength of only 10.5 MPa, a high and low temperature resistance retention rate of 83.0%, and fails to meet waterproof performance standards. Comparative Example 2, after replacing the hydroxyl-terminated polybutadiene with polytetrahydrofuran ether glycol, has a tensile shear strength of 13.8 MPa and a high and low temperature resistance retention rate of 76.3%, but its overall performance is inferior to the products in the Example series. The combined use of hydroxyl fluorosilicone oil, poly(2-ethyl-2-oxazoline)-diamino end-capping, and hydroxyl-terminated polybutadiene has a positive effect on improving the above-mentioned performance.

[0054] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive, characterized in that, The product comprises the following components by weight: 50-60 parts of composite soft segment polyol, 20-25 parts of modified isocyanate component, 5-8 parts of dynamic crosslinking chain extender, 4-7 parts of functional component, and 0.08-0.25 parts of catalyst; the functional component includes nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capping agent; the composite soft segment polyol is a poly… The mixture consists of tetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene in a mass ratio of 2:1:(0.5-1); the modified isocyanate component consists of carbodiimide-modified MDI and hexamethylene diisocyanate trimer in a mass ratio of (2.5-3):0.5; the dynamic crosslinking chain extender consists of 1,4-butanediol, dicaprolactam disulfide, and N-methyldiethanolamine in a mass ratio of 3:1:(0.8-1.2).

2. The high and low temperature resistant, high adhesion polyurethane hot melt adhesive according to claim 1, characterized in that, The polytetrahydrofuran ether diol is polytetrahydrofuran ether diol PTMG-2000; the polycaprolactone diol is polycaprolactone diol PCL-2000; and the hydroxyl-terminated polybutadiene is hydroxyl-terminated polybutadiene HTPB-2000.

3. The high and low temperature resistant, high adhesion polyurethane hot melt adhesive according to claim 1, characterized in that, The carbodiimide-modified MDI is model Wanhua CDMDI-100L.

4. The high and low temperature resistant, high adhesion polyurethane hot melt adhesive according to claim 1, characterized in that, The mass ratio of the nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, polyamide wax thixotropic agent, hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is (1-3):(0.8-2):(0.3-1):(0.5-1.5):(0.4-0.8):(0.3-1):(0.5-1.5).

5. The high and low temperature resistant, high adhesion polyurethane hot melt adhesive according to claim 1, characterized in that, The average particle size of the nano-aluminum nitride is 50-80 nm; the silane coupling agent is silane coupling agent KH560; the ultraviolet absorber is light stabilizer UV-3808PP5; and the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

6. The high and low temperature resistant, high adhesion polyurethane hot melt adhesive according to claim 1, characterized in that, The polyamide wax thixotropic agent is polyamide wax NEW-0402E; the hydroxyl fluorosilicone oil has a number-average molecular weight of 1000-2000 and a hydroxyl value of 40-60 mgKOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number-average molecular weight of 1000-2000.

7. The high and low temperature resistant, high adhesion polyurethane hot melt adhesive according to claim 1, characterized in that, The catalyst is a mixture of dibutyltin dilaurate and bismuth isooctanoate in a mass ratio of 1:(2-3).

8. A method for preparing a high- and low-temperature resistant, high-adhesion polyurethane hot melt adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Add polytetrahydrofuran ether glycol, polycaprolactone glycol and hydroxyl-terminated polybutadiene into a vacuum dehydration kettle, add polyamide wax thixotropic agent, heat to 120-130℃, and dehydrate under a vacuum of -0.1MPa for 2-3 hours; then cool to 65-70℃, turn on a high-speed disperser and stir at 1500-1800r / min for 30-40 minutes to completely melt and disperse the polyamide wax, forming a homogeneous composite soft segment system; Step S2: Transfer the composite soft segment system prepared in step S1 into a nitrogen-protected reactor, add carbodiimide-modified MDI, and stir at 600-800 r / min for 30 min at 70℃; then gradually increase the temperature to 85℃ at a rate of 5℃ / h, and maintain the temperature for 1.5-2 h; then add hexamethylene diisocyanate trimer, and continue the reaction at 90℃ for 1-1.5 h. Step S3: Cool the prepolymer system to 60°C, and add the mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEO2-NH2 dropwise to the reactor at a rate of 1-1.5 mL / min. After the addition is complete, keep the temperature for 40-50 min; then raise the temperature to 70°C and continue the reaction for 1 h. Step S4: Lower the system temperature to 65-70℃, add nano aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, and hydroxyl fluorosilicone oil, and stir to form a uniform slurry; add the mixture to the reactor and disperse at a high speed of 1800-2000 r / min for 2-2.5 h. Step S5: Add the catalyst to the reactor and stir at 800-1000 r / min for 30-40 min; then, devolve at 80℃ and -0.09MPa vacuum for 30-40 min to remove bubbles in the system. Under nitrogen purging protection, extrude and granulate the material, rapidly cool it to below 30℃, and vacuum seal and package it to obtain a high and low temperature resistant, high adhesion polyurethane hot melt adhesive.