Polyurethane hot melt adhesive with high and low temperature resistance and high adhesion and preparation method thereof

Abstract

The invention discloses a polyurethane hot melt adhesive with high and low temperature resistance and high adhesion and a preparation method thereof, and relates to the technical field of hot melt adhesives. The invention relates to a dynamic crosslinking polyurethane elastomer, which is prepared from the following ingredients in parts by weight: 50 to 60 parts of composite soft-segment polyol, 20 to 25 parts of modified isocyanate ingredients, 5 to 8 parts of dynamic crosslinking chain extenders, 4 to 7 parts of functional ingredients and 0.08 to 0.25 part of catalysts. The functional components comprise nano aluminum nitride, a silane coupling agent, an ultraviolet light absorber, an antioxidant, a polyamide wax thixotropic agent, hydroxyl fluorosilicone oil and a poly (2-ethyl-2-oxazoline)-bis-amino-terminated part. The hot melt adhesive has wide temperature range tolerance, high binding power and waterproofness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot melt adhesives, and particularly relates to a high-low temperature resistant and high-adhesion polyurethane hot melt adhesive and a preparation method thereof. BACKGROUND

[0002] As an environmentally friendly adhesive, polyurethane hot melt adhesive is widely used in the fields of automobiles, electronics, packaging, etc. Traditional polyurethane hot melt adhesives have obvious deficiencies in high-low temperature resistance and adhesion. Under low temperature conditions, the flexibility of the adhesive molecular chain decreases, and brittle fracture easily occurs, leading to peeling of the bonding interface. In a high temperature environment, the thermal motion of the molecular chain is intensified, the stability of the cross-linked structure decreases, softening and creep occur, and the bonding strength is greatly attenuated, which cannot meet the needs of the use scenarios of automobile engines, outdoor electronic devices, etc. in a wide temperature range.

[0003] To improve the high-low temperature resistance, the prior art often uses a single type of polyol (such as pure polyether or pure polyester) as the soft segment, but there is a performance imbalance problem: the pure polyether type polyurethane hot melt adhesive has good low temperature resistance, but insufficient high temperature resistance and mechanical strength; the pure polyester type product has improved high temperature resistance, but poor low temperature toughness and is prone to brittle fracture. At the same time, some schemes add inorganic fillers (such as calcium carbonate, silicon dioxide) to enhance the high temperature resistance, but uneven dispersion of the fillers can easily lead to bonding interface defects, thereby reducing the adhesion. The addition of a large amount of fillers also sacrifices the construction fluidity. The polyurethane hot melt adhesives on the market are also difficult to balance the high-low temperature resistance and the bonding strength at the same time.

[0004] To solve the above problems, patent document CN114736644B discloses a transparent edge sealing adhesive and a preparation method thereof. The preparation raw materials include the following components in parts by weight: polyether polyol 5-15 parts, polyester polyol 40-80 parts, transparent polyurethane elastomer 5-30 parts, copolyester 5-20 parts, chain extender 5-15 parts, isocyanate 10-20 parts, and auxiliary agent 0.01-3 parts. The transparent edge sealing adhesive prepared in the application is a solvent-free adhesive with a solid content of 100%, which effectively avoids pollution caused by solvents and ensures smooth glue discharge, effectively improving the problem of rapid shrinkage of crystalline polyester-based edge sealing adhesive when exposed to cold. Secondly, the transparent edge sealing adhesive of the application has no stringing problem when edge sealing is applied, and does not cause defects such as foreign matter on the substrate; moreover, it also has certain cleaning-free properties, and does not need to be cleaned for 72 hours of continuous use at a continuous hot melt temperature of 120-160 DEG C. However, its waterproof performance, temperature resistance and adhesion strength still need to be further improved. SUMMARY

[0005] The present application aims to overcome the deficiencies in the prior art and provide a high-low temperature resistant and high-adhesion polyurethane hot melt adhesive with wide temperature range resistance, high adhesion and waterproof properties, and a preparation method thereof.

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

[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 type of the carbodiimide modified MDI is Wanhua CDMDI-100L, and the CAS number is 25686-28-6.

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

[0012] Preferably, the mass ratio of the nano aluminum nitride, the silane coupling agent, the ultraviolet absorber, the antioxidant, the polyamide wax thixotropic agent, the hydroxyl fluorosilicone oil and the poly(2-ethyl-2-oxazoline)-diamino end-capped 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 light stabilizer UV-3808PP5.

[0016] Preferably, the antioxidant is at least one of antioxidant 1010, 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 poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number average molecular weight of 1000-2000.

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

[0021] Another object of the present application is to provide a preparation method of the high-temperature-resistant and high-adhesion polyurethane hot melt adhesive. Step S1, polytetrahydrofuran ether diol, polycaprolactone diol and hydroxyl-terminated polybutadiene are put into a vacuum dehydration kettle, polyamide wax thixotropic agent is added, the temperature is raised to 120-130℃, and dehydration is carried out at a vacuum degree of-0.1 MPa for 2-3 h; then the temperature is lowered to 65-70℃, a high-speed disperser is turned on to stir at 1500-1800 r / min for 30-40 min, so that the polyamide wax is completely melted and dispersed to form a homogeneous composite soft segment system; Step S2, the composite soft segment system prepared in step S1 is transferred into a reaction kettle protected by nitrogen, carbodiimide-modified MDI is added, and stirring is carried out at 600-800 r / min at 70℃ for 30 min; then the temperature is raised to 85℃ at a rate gradient of 5℃ / h, and the reaction is kept for 1.5-2 h; then hexamethylene diisocyanate trimer is added, and the reaction is continued at 90℃ for 1-1.5 h; Step S3, the prepolymer system is cooled to 60℃, and a mixture of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 is added to the reaction kettle at a rate of 1-1.5 mL / min, and after the addition is completed, the reaction is kept for 40-50 min; then the temperature is raised to 70℃, and the reaction is continued for 1 h; Step S4, the temperature of the system is lowered to 65-70℃, and nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant and hydroxyl fluorosilicone oil are added, and stirring is carried out to form a uniform slurry; the mixture is added to the reaction kettle, and high-speed dispersion is carried out at 1800-2000 r / min for 2-2.5 h. Step S5, the catalyst is added into the reaction kettle, stirring at 800-1000 r / min for 30-40 min; then devolatilization is carried out at 80 DEG C, -0.09 MPa vacuum degree for 30-40 min, remove the bubble in the system, under the protection of nitrogen blowing, the material is extruded into granules, fast cooling to below 30 DEG C, vacuum sealed packaging, high and low temperature resistant, high adhesive polyurethane hot melt adhesive is obtained.

[0022] Due to the use of the above technical solutions, the present application has the following beneficial effects: (1) The high and low temperature resistant, high adhesive polyurethane hot melt adhesive disclosed by the present application breaks through the performance imbalance bottleneck caused by the existing single polyether or polyester soft segment through the synergistic design of composite soft segment polyol. 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 the 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. After the three are compounded in a specific proportion, the synergistic effect of "low temperature flexibility-high temperature stability-strong and tough overall" is formed, so that the hot melt adhesive maintains structural stability in a wide temperature range, solving the core pain points of traditional products such as low temperature brittle fracture and high temperature creep.

[0023] (2) The high and low temperature resistant, high adhesive polyurethane hot melt adhesive disclosed by the present application realizes the synchronous improvement of bonding strength and environmental resistance through the innovative collocation of modified isocyanate component. The carbodiimide bond introduced by carbodiimide modified MDI not only has excellent hydrolysis resistance, but also can reduce the crystallization rate of the system, avoiding stress concentration in the adhesive layer; the multi-functionality structure of hexamethylene diisocyanate trimer significantly improves the crosslinking density, enhancing the high temperature creep resistance of the adhesive layer. After the two are compounded in a specific proportion, compared with the existing single isocyanate system, the interfacial bonding strength of the adhesive layer with metal, plastic, rubber and other substrates is improved, and the wet heat aging performance is greatly optimized.

[0024] (3) The high and low temperature resistant, high adhesive polyurethane hot melt adhesive disclosed by the present application, the multi-component design of dynamic crosslinking chain extender endows the system with unique wide temperature range adaptation ability, realizing the dynamic adjustment of "rigidity-flexibility". 1,4-Butanediol provides basic crosslinking strength, and the dynamic disulfide bond introduced by dithiohexanamide can be reversibly broken and recombined when the temperature changes, relieving the internal stress of the molecular chain in a wide temperature range, avoiding brittle fracture at low temperature and excessive softening at high temperature; the tertiary amine group of N-methyldiethanolamine enhances the polarity of the molecular chain, improving the interaction with polar substrates. This dynamic crosslinking system makes the hot melt adhesive still maintain good flexibility in low temperature environment, and has no obvious creep at high temperature, breaking through the technical limitations of the existing static crosslinking system which is difficult to consider both high and low temperature performance.

[0025] (4) The high-temperature-resistant and low-temperature-resistant polyurethane hot melt adhesive with high adhesive force disclosed in the application solves the contradiction between "enhancement and flow, waterproof and adhesion" in the prior art through the synergistic effect of functional components. The nano-aluminum nitride is uniformly dispersed by virtue of high specific surface area and surface modification of the 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 the hydroxyl fluorosilicone oil endows the adhesive layer with excellent waterproofness, and does not affect the adhesion compatibility of the adhesive layer and the substrate; the polar segment of poly(2-ethyl-2-oxazoline)-diamino-terminated forms a strong interaction with the surface active groups of the substrate, further strengthening the adhesive force; the ultraviolet absorber, antioxidant and the above-mentioned components synergistically improve the weather resistance of the adhesive layer and prolong the outdoor service life. The functional system makes the hot melt adhesive maintain excellent construction fluidity while synchronously improving the adhesive strength, waterproofness and weather resistance, solving the technical problems of sacrificing the construction performance and reducing the adhesive force caused by adding functional fillers to improve waterproofness in the prior art.

[0026] (5) The high-temperature-resistant and low-temperature-resistant polyurethane hot melt adhesive with high adhesive force disclosed in the application ensures full reaction and uniform dispersion of each component through precise control of the preparation process. The combination of vacuum dewatering and high-speed dispersion makes the polyamide wax thixotropic agent completely melt, avoiding the influence of thixotropic agent agglomeration on the flatness of the adhesive layer; the gradient heating and dropwise addition of the chain extender control the reaction rate, reduce the occurrence of side reactions and ensure the uniformity of the prepolymer structure; the high-temperature vacuum devolatilization and nitrogen protection process removes bubbles and impurities in the system, improving the density of the adhesive layer. The final product not only significantly outperforms the prior art in terms of wide temperature resistance, high adhesive force and waterproofness, but also has good processing stability and storage stability, which can meet the use requirements of harsh scenes such as automobile engine periphery, outdoor electronic equipment and high-end packaging, filling the gap of existing polyurethane hot melt adhesives in wide temperature range and high requirement application scenes. DETAILED DESCRIPTION

[0027] The following description is used to disclose the application so that those skilled in the art can implement the application. The preferred embodiments in the following description are only as examples, and other obvious modifications can be conceived by those skilled in the art. Example 1

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

[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 of model Wanhua CDMDI-100L and CAS number 25686-28-6; and the dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dithiohexamethylene amide and N-methyldiethanolamine in a mass ratio of 3:1:0.8.

[0030] The mass ratio of the nano-aluminum nitride, the silane coupling agent, the ultraviolet absorber, the antioxidant, the polyamide wax thixotropic agent, the hydroxyl fluorosilicone oil and the 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; 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 mgKOH / g; the poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 has a number average molecular weight of 1000; and the catalyst is a mixture of dibutyltin dilaurate and bismuth isooctoate in a mass ratio of 1:2.

[0031] A preparation method of the high-temperature-resistant and low-temperature-resistant polyurethane hot melt adhesive with high adhesive force, comprising the following steps: Step S1, polytetrahydrofuran ether diol, polycaprolactone diol and hydroxyl-terminated polybutadiene are put into a vacuum dehydration kettle, polyamide wax thixotropic agent is added, the temperature is raised to 120℃, and dehydration is performed under a vacuum degree of-0.1 MPa for 2 h; then the temperature is lowered to 65℃, a high-speed disperser is started to stir at 1500 r / min for 30 min, so that the polyamide wax is completely melted and dispersed to form a homogeneous composite soft segment system; Step S2, the composite soft segment system prepared in step S1 is transferred into a reaction kettle protected by nitrogen, carbodiimide-modified MDI is added, and stirring is performed at 600 r / min at 70℃ for 30 min; then the temperature is raised to 85℃ at a gradient of 5℃ / h, and the reaction is kept for 1.5 h; then hexamethylene diisocyanate trimer is added, and the temperature is raised to 90℃ for continuous 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. Item Tensile Shear Strength Resistance to High and Low Temperature Water Resistance Unit MPa % — Example 1 16.2 93.5 Pass Example 2 17.0 94.8 Pass Example 3 17.6 95.2 Pass Example 4 18.1 96.1 Pass Example 5 18.5 96.8 Pass Comparative Example 1 10.5 83.0 Fail Comparative Example 2 13.8 76.3 Pass 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 adhesive strength polyurethane hot melt adhesive, characterized in that, The polyurethane adhesive comprises the following components by weight: 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, a hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capped. 2.The high temperature resistant and low temperature resistant polyurethane hot melt adhesive with high adhesive force according to claim 1, characterized in that, The composite soft segment polyol is a mixture of polytetrahydrofuran ether diol, polycaprolactone diol, and hydroxyl-terminated polybutadiene at a mass ratio of 2:1:(0.5-1). 3.The high temperature resistant and low temperature resistant polyurethane hot melt adhesive with high adhesive force according to claim 2, 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. 4.The high temperature resistant and low temperature resistant polyurethane hot melt adhesive with high adhesive force according to claim 1, characterized in that, The modified isocyanate component is a mixture of carbodiimide-modified MDI and hexamethylene diisocyanate trimer at a mass ratio of (2.5-3):0.5; the carbodiimide-modified MDI is of the type Wanhua CDMDI-100L. 5.The high temperature resistant and low temperature resistant polyurethane hot melt adhesive with high adhesive force according to claim 1, characterized in that, The dynamic crosslinking chain extender is a mixture of 1,4-butanediol, dithiohexamethylene amide, and N-methyl diethanolamine at a mass ratio of 3:1:(0.8-1.2). 6.The high temperature resistant and low temperature resistant polyurethane hot melt adhesive with high adhesive force according to claim 1, characterized in that, The mass ratio of the nano-aluminum nitride, the silane coupling agent, the ultraviolet absorber, the antioxidant, the polyamide wax thixotropic agent, the hydroxyl fluorosilicone oil, and poly(2-ethyl-2-oxazoline)-diamino end-capped 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). 7.The high-temperature resistant and low-temperature resistant polyurethane hot melt adhesive with high adhesive force 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. 8.The high-low temperature resistant and high adhesive 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; and the poly(2-ethyl-2-oxazoline)-diamino end-capped NH2-PEOz-NH2 has a number average molecular weight of 1000-2000. 9.The high temperature resistant and high adhesive polyurethane hot melt adhesive according to claim 1, wherein, The catalyst is a mixture of dibutyltin dilaurate and bismuth isooctoate at a mass ratio of 1:(2-3).

10. The method for preparing the high-temperature-resistant and low-temperature-resistant polyurethane hot melt adhesive with high adhesive force according to claim 4, characterized in that, The method comprises the following steps: In step S1, the polytetrahydrofuran ether diol, the polycaprolactone diol, and the hydroxyl-terminated polybutadiene are put into a vacuum dehydration kettle, the polyamide wax thixotropic agent is added, the temperature is raised to 120-130℃, and the dehydration is performed at a vacuum degree of -0.1 MPa for 2-3 h; then the temperature is lowered to 65-70℃, the high-speed dispersion machine is started to stir at 1500-1800 r / min for 30-40 min, the polyamide wax is completely melted and dispersed, and a homogeneous composite soft segment system is formed. Step S2, the composite soft segment system prepared in step S1 was transferred into a reaction kettle under nitrogen protection, and carbodiimide modified MDI was added, and stirred at 600-800 r / min at 70 ℃ for 30 min; then the temperature was increased to 85 ℃ at a rate of 5 ℃ / h, and the reaction was kept for 1.5-2 h; then hexamethylene diisocyanate trimer was added, and the temperature was increased to 90 ℃ for further reaction for 1-1.5 h; Step S3, the prepolymer system was cooled to 60 ℃, and the mixed solution of dynamic crosslinking chain extender and poly(2-ethyl-2-oxazoline)-diamino-terminated NH2-PEOz-NH2 was added into the reaction kettle at a rate of 1-1.5 mL / min, and after the addition was completed, the reaction was kept for 40-50 min; then the temperature was increased to 70 ℃, and the reaction was continued for 1 h; Step S4, the temperature of the system was reduced to 65-70 ℃, and nano-aluminum nitride, silane coupling agent, ultraviolet absorber, antioxidant, hydroxyl fluorosilicone oil were added, and stirred to form a uniform slurry; the mixed solution was added into the reaction kettle, and dispersed at a high speed of 1800-2000 r / min for 2-2.5 h; Step S5, the catalyst was added into the reaction kettle, and stirred at 800-1000 r / min for 30-40 min; then the system was degassed at 80 ℃ and a vacuum degree of-0.09 MPa for 30-40 min to remove the bubbles in the system, and the material was extruded and granulated under the protection of nitrogen blowing, and quickly cooled to below 30 ℃, and vacuum sealed packaging, to obtain a high and low temperature resistant, high adhesive force polyurethane hot melt adhesive.