Quick-positioning pressure-maintaining-free silane modified UV moisture dual-curing polyurethane hot-melt adhesive and preparation method thereof

Abstract

The invention relates to the field of adhesives, in particular to a quick-positioning pressure-maintaining-free silane modified UV moisture dual-curing polyurethane hot-melt adhesive and a preparation method thereof. The invention relates to a quick-positioning pressure-maintaining-free silane-modified UV (ultraviolet) moisture dual-curing polyurethane hot-melt adhesive. Comprising the following components: amorphous polyester polyol, crystalline polyester polyol, amorphous polyether polyol, hyperbranched modified rosin resin, a catalyst, isocyanate, an MS modified silane polymer, an acrylate monomer, a photoinitiator, a siloxane end-capping reagent, an organic tin catalyst, vinyl trimethoxy silane and an antioxidant. By dispensing and UV irradiation curing at the same time, the adhesive forms higher initial bonding strength in a short time, the final bonding strength is improved, and the application of the adhesive in precise scenes such as narrow frames is ensured.

Description

Technical Field

[0001] This application relates to the field of adhesives, and more particularly to a rapid-positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive and its preparation method. Background Technology

[0002] Reactive polyurethane hot melt adhesives, as environmentally friendly adhesives, combine the convenient processing characteristics of ordinary hot melt adhesives with the fact that they contain active isocyanate groups, which can undergo a curing and cross-linking reaction with moisture in the air at room temperature, thereby obtaining excellent bonding performance, good flexibility and weather resistance. They have been widely used in many industries such as consumer electronics, woodworking, home appliances, and textiles, providing reliable bonding solutions for the manufacturing and assembly of various products.

[0003] With the rapid development of the consumer electronics and display industries, touchscreen phones and monitors with high screen-to-body ratios and narrow bezels are gradually becoming the mainstream in the market. This trend has placed more stringent demands on the performance of adhesives. The narrow bezel design significantly reduces the bonding area, requiring higher standards for adhesive bonding strength. While the application of traditional PUR hot melt adhesives in bezel bonding scenarios is becoming increasingly common, there are still many areas for optimization: the production process is relatively long, requiring a certain period of pressure holding after application, which affects overall production efficiency to some extent; during application, improper temperature control or inappropriate adhesive thickness can lead to insufficient evaporation of the gas released from the reaction of isocyanate groups and hydroxyl groups, easily causing pores to form inside the adhesive and affecting the stability of bonding strength; simultaneously, with the increasing maturity of composite materials and metal surface treatment processes, the market's requirements for the multi-substrate bonding compatibility of adhesives are constantly increasing. The presence of isocyanate groups in traditional single-component PUR hot melt adhesives makes it difficult to add amino-based silane coupling agents, resulting in inconsistent bonding performance on different substrates and failing to fully meet the bonding needs of narrow-bezel products. Summary of the Invention

[0004] To overcome the shortcomings of existing polyurethane hot melt adhesives in terms of bonding performance, this application provides a rapid-positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive and its preparation method.

[0005] In a first aspect, this application provides a rapid-positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive, employing the following technical solution: A rapid-positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive comprises the following components in parts by weight: 10-50 parts of amorphous polyester polyol, 5-25 parts of crystalline polyester polyol, 5-50 parts of amorphous polyether polyol, 1-8 parts of hyperbranched modified rosin resin, 0.01-0.2 parts of catalyst, 1-10 parts of isocyanate, 1-50 parts of MS-modified silane polymer, 0.1-10 parts of acrylate monomer, 0.5-5 parts of photoinitiator, 1-6 parts of siloxane end-capping agent, 0.2-1 part of organotin catalyst, 0.2-2 parts of vinyltrimethoxysilane, and 0.1-1 part of antioxidant.

[0006] Preferably, the composition includes 30-50 parts of amorphous polyester polyol, 15-25 parts of crystalline polyester polyol, 20-50 parts of amorphous polyether polyol, 1-8 parts of hyperbranched modified rosin resin, 0.01-0.2 parts of catalyst, 1-10 parts of isocyanate, 10-30 parts of MS modified silane polymer, 0.1-10 parts of acrylate monomer, 0.5-5 parts of photoinitiator, 1-6 parts of siloxane end-capping agent, 0.2-1 parts of organotin catalyst, 0.2-2 parts of vinyltrimethoxysilane, and 0.1-1 parts of antioxidant.

[0007] This application achieves a polymer backbone primarily composed of hydroxyl groups by controlling the selection and polymerization ratio of isocyanate and polyol. A siloxane end-capping agent reacts with some of the hydroxyl groups, transforming the moisture curing mechanism from the bubble-generating -NCO route to a bubble-free siloxane moisture curing route. During the moisture reaction, the siloxane releases methanol, eliminating gas generation and preventing micropores from forming inside the cured colloid, which would affect strength. It also improves the interaction with the silane coupling agent, ensuring good adhesion to multiple substrates and enhancing the adhesive's broad-spectrum compatibility with complex composite materials. The remaining hydroxyl groups are introduced into UV-curable groups through double bond grafting with acrylate monomers, enabling the adhesive to achieve initial strength within seconds, meeting assembly requirements and eliminating the long pressure holding time required by traditional PUR adhesives. Ultimately, this results in a silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive. The UV / moisture curing mechanisms work together, with UV curing responsible for rapid shaping and siloxane moisture curing responsible for long-term enhancement. This allows for simultaneous UV curing during adhesive dispensing, quickly achieving the initial bond strength required for product assembly and proceeding to subsequent assembly processes. This avoids the traditional pressure holding stage of PUR hot melt adhesives, ensuring high reliability and efficiency of the adhesive in precision scenarios such as narrow bezels.

[0008] In this process, amorphous polyester polyols, crystalline polyester polyols, and amorphous polyether polyols work together. Crystalline polyester polyols form crystalline structures that act as physical crosslinking points, while the chains of amorphous polyester polyols and amorphous polyether polyols become entangled with them, restricting molecular chain slippage and enhancing cohesive strength. The polarity difference between amorphous and crystalline polyols also creates a polar gradient, further enhancing cohesive strength and thus improving the adhesive's adhesion. Furthermore, hyperbranched modified rosin resin is introduced. Rosin resin itself has excellent initial tack, which can initially improve the bonding strength at the adhesive interface. After hyperbranching modification, a highly branched three-dimensional spatial structure is formed, and the steric hindrance effect reduces the probability of resin molecule aggregation. Simultaneously, the active groups introduced into the hyperbranched structure can interact with the functional groups of polyols, polyurethane prepolymers, etc., improving dispersion uniformity. Hyperbranching significantly enhances the density and stability of the crosslinking network. Moreover, its high specific surface area increases the contact area with the substrate, preventing interfacial separation, improving the bonding strength at the adhesive interface, and thus improving the adhesive's performance. Polyols and hyperbranched modified rosin resins work together to enhance the overall stability of silane-modified UV-curable moisture-cured polyurethane hot melt adhesives. MS-modified silane polymers further improve adhesion and adjust toughness; vinyltrimethoxysilane acts as an auxiliary moisture-curing crosslinking agent and storage stabilizer; antioxidants prevent high-temperature oxidation, ultimately achieving a highly efficient and stable polyurethane hot melt adhesive with rapid UV initial curing and deep siloxane moisture curing.

[0009] Preferably, the amorphous polyester polyol is polypropylene adipate diol with a molecular weight of 1000-5000; the crystalline polyester polyol is polycaprolactone diol with a molecular weight of 1000-5000; and the amorphous polyether polyol is polytetramethylene ether diol with a molecular weight of 1000-2000.

[0010] More preferably, the mass ratio of poly(propylene adipate) glycol: polycaprolactone glycol: polytetramethylene ether glycol is 3:1:2.

[0011] Polycaprolactone diol has a short-chain crystalline structure, and its crystallinity makes the molecular arrangement relatively regular and orderly, which can serve as the basis for physical cross-linking. The long chains of polyhexamethylene adipate can wrap around the crystalline structure of polycaprolactone diol to form a long-chain entanglement structure, which restricts molecular chain slippage and enhances cohesive strength. By using crystalline and amorphous polyester polyols and polyether polyols of different molecular weights in the proportions disclosed in this application, a dense three-dimensional polyurethane network is formed after cross-linking with isocyanate. The presence of the short-chain crystalline structure of polycaprolactone diol makes the cross-linking points more uniform and dense, while the long chains of polyhexamethylene adipate connect each crystalline anchor point. The flexible ether chains of polytetrahydrofuran diol fill the gaps between them, which together improves the uniformity of adhesion to the substrate, reduces void defects, and enhances density. It can also improve the compatibility with tackifying resins, strengthen interfacial bonding, and thus improve shear strength, thereby improving the overall adhesive performance of polyurethane adhesives.

[0012] Preferably, the preparation method of hyperbranched modified rosin resin includes: under nitrogen protection, taking hydrogenated rosin glycerol ester, 2,2-dimethylolpropionic acid, and toluene diisocyanate, adding dibutyltin dilaurate, and reacting at 70-85℃ for 3-5 hours; adding trimethylolpropane, and reacting at 90-100℃ for 2-5 hours; cooling to 60-70℃, adding hydroxyethyl methacrylate, and reacting for 1-3 hours; cooling to 40-50℃ and degassing under vacuum to obtain hyperbranched modified rosin resin.

[0013] Based on the hydrogenation of rosin glycerol esters, a branched structure is introduced, and the terminal isocyanate groups are converted into carbon-carbon double bonds. The resulting hyperbranched modified rosin resin has a highly branched structure, which reduces the probability of resin molecule aggregation, improves its dispersion uniformity, and enhances the compatibility between the tackifying resin and the substrate. The hyperbranched structure contains terminal C=C double bonds and internal hydroxyl and ester bonds. The terminal C=C double bonds can participate in UV-cured free radical copolymerization, further improving the photocuring efficiency. The internal functional groups can interact with the polyurethane matrix, and its hyperbranched structure can improve the density and stability of the polyurethane network. At the same time, the high specific surface area of ​​the hyperbranched structure increases the contact area with the substrate, avoids interfacial separation, improves the bonding force at the adhesive interface, further enhances the cohesive strength, thereby improving the shear strength and improving the problem of uneven adhesion between multiple substrates, which meets the needs of narrow bezel applications.

[0014] Preferably, the siloxane end-capping agent is one or more of isocyanate-based trimethoxysilane, isocyanate-based triethoxysilane, amino-based trimethoxysilane, isocyanate-based methyldimethoxysilane, and bis(3-trimethoxysilylpropyl)amine.

[0015] More preferably, the siloxane end-capping agent is isocyanate-based trimethoxysilane.

[0016] Using siloxane end-capping agents can transform the moisture curing mechanism from the bubble-generating -NCO route to a bubble-free siloxane route, avoiding the influence of micropores on strength after colloid curing. In this application, the reaction system is a prepolymer with excess hydroxyl groups. The -NCO end of the isocyanate-based trimethoxysilane can react with the -OH at the end of the prepolymer to form a stable urethane bond, firmly attaching the -Si(OCH3)3 group to the end of the polymer chain. This transforms the moisture curing mechanism from the bubble-generating -NCO route to a bubble-free siloxane route. Since the moisture curing byproduct of siloxanes is volatile methanol, the generation of curing bubbles is fundamentally eliminated. By attaching the moisture curing functional group to the end of the polymer chain, the shear strength is improved. Moreover, compared with aminosilanes and bis(3-trimethoxysilylpropyl)amine, there are fewer reaction byproducts, resulting in a more stable system.

[0017] Preferably, the isocyanate is a diisocyanate.

[0018] Preferably, the catalyst is selected from one or more of organobismuth, organotin, organosilver, organoaluminum, organotitanium, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0019] Preferably, the acrylate monomer is one or both of isocyanate methacrylate and isocyanate ethyl acrylate.

[0020] In this application, the acrylate monomer provides C=C double bond active sites for UV curing, while simultaneously regulating the compatibility and curing reaction characteristics of the adhesive layer. In the process of this application, the isocyanate methacrylate molecule has both C=C double bonds and NCO groups. The C=C double bonds undergo rapid free radical copolymerization to form a dense initial cross-linked network, meeting the immediate strength requirements of simultaneous application and UV curing. The NCO groups can react with the remaining hydroxyl groups after chain extension, achieving directional and uniform grafting of C=C double bonds onto the polymer molecular chain, further enhancing the cohesive strength of the adhesive layer. In addition, its bifunctional characteristics enable UV curing and subsequent moisture curing to work synergistically, ensuring the initial strength required for assembly without interfering with the moisture curing of siloxane end-capsulation, thus avoiding the separation of the UV curing and moisture curing phases.

[0021] Preferably, the MS-modified silane polymer is one or both of methoxy-terminated polyether-modified silane polymers and ethoxy-terminated polyether-modified silane polymers.

[0022] Methoxy-terminated polyether-modified silane polymers, as MS-modified silane polymers, introduce methoxy groups to enable them to participate in the aforementioned moisture-curing reaction. Combined with the silanol groups generated from the hydrolysis of isocyanate-based trimethoxysilane grafted onto the polymer, they further densify the cross-linked network, enhancing the final adhesive strength and weather resistance of the adhesive layer. Furthermore, the reaction process releases methanol without generating gas. Its polyether backbone possesses excellent flexibility and compatibility, filling the molecular gaps in the cross-linked network, relieving internal stress during curing, and preventing brittle fracture of the adhesive layer. Simultaneously, it improves the interfacial wettability between the adhesive and different substrates. This ensures assembly processes that involve simultaneous application of adhesive and UV irradiation, while also allowing the adhesive layer to meet the high adhesive strength and process requirements of narrow-bezel products by adjusting its flexibility and adhesion, achieving dual optimization of performance and process.

[0023] Preferably, the photoinitiator is one or more of 1173, 189, TPO-L, 184, TPO, MBF, 907, and 659.

[0024] More preferably, the photoinitiator is photoinitiator 1173 or photoinitiator TPO-L with a mass ratio of 2:1.

[0025] Secondly, this application provides a method for preparing a rapid-positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive, employing the following technical solution: A method for preparing a rapid-positioning, pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive includes the following steps: (1) Take amorphous polyester polyol, crystalline polyester polyol, and amorphous polyether polyol respectively and vacuum dehydrate them at 100-120℃ for 0.5-1h. After releasing the vacuum, stir and add hyperbranched modified rosin resin and antioxidant. Then raise the temperature to 120-130℃ and vacuum dehydrate for 60-90min. Then add isocyanate and, under a nitrogen atmosphere, adjust the temperature to 80-110℃ and vacuum stir under an absolute pressure ≤100Pa for 1- 3h; (2) Cool to 75-85℃, then add siloxane end-capping agent and catalyst, stir and react for 1-3h; (3) Adjust the system temperature to 60-80℃, add acrylate monomer, and continue stirring and react for 0.5-1h; (4) Add MS modified silane polymer, and continue stirring for 0.5h; (5) Under light-protected conditions, cool to 50-60℃, add MS modified silane polymer, vinyltrimethoxysilane, photoinitiator and organotin catalyst, and continue stirring for 20-60min; obtain rapid positioning pressure-free silane modified UV moisture dual-curing polyurethane hot melt adhesive. In summary, this application has the following beneficial effects: 1. This application achieves a polymer backbone primarily composed of hydroxyl groups at the ends by controlling the selection and polymerization ratio of isocyanate and polyol. The excess of hydroxyl groups avoids the bubble problem caused by excessive -NCO in traditional one-component PUR hot melt adhesives, while also enhancing interactions with silanes and grafting methacrylic double bonds onto the polymer chain, thus providing instantaneous UV-cured strength to meet rapid assembly requirements. A siloxane end-capping agent introduces moisture-curing groups at the polymer chain ends, achieving deep curing and improved adhesive strength. This completely avoids the bubble problem caused by carbon dioxide generation during traditional isocyanate moisture curing, ensuring a highly efficient assembly process with simultaneous dispensing and UV irradiation. It quickly achieves the initial adhesive strength required for product assembly, allowing for subsequent assembly processes and avoiding the pressure-holding stage of traditional PUR hot melt adhesives. Together, these factors ensure high reliability and efficiency of the adhesive in precision scenarios such as narrow bezels.

[0026] 2. Hyperbranched modified rosin resin reduces the probability of resin molecule aggregation due to its steric hindrance effect. At the same time, the ester bonds introduced into the structure can interact with the functional groups of polyurethane prepolymer, improving the dispersion uniformity, solving the problem of poor compatibility between the tackifying resin and the main body, improving the density and stability of the crosslinking network, enhancing cohesive strength, and increasing shear strength. Furthermore, the terminal carbon-carbon double bonds contained in the hyperbranched structure can participate in the free radical copolymerization of UV curing, improving the UV curing efficiency. Detailed Implementation

[0027] The present application will be further described in detail below with reference to the embodiments.

[0028] Some of the raw materials used in the preparation examples and embodiments: polytetramethylene ether glycol: Nan Ya Formosa Plastics FASPTMG2000; polypropylene adipate glycol: PPA-2000; polycaprolactone glycol: PCL-1000; catalyst: bismuth isooctanoate (20%): Shandong Longhui Chemical Co., Ltd.; hydrogenated rosin glycerol ester: GEHR-85ER purchased from Wuhan Yuancheng Technology Development Co., Ltd.; diisocyanate: TDI-80; methoxy-terminated polyether modified silane polymer: Wacker GENIOSIL XT 120; silane-terminated polyether modified polyurethane prepolymer: Silquest SPUR+1015; organotin catalyst: dibutyltin dilaurate; vinyltrimethoxysilane: A-171 purchased from Momentive; antioxidant 1010. Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.

[0029] Preparation Example 1 Preparation of hyperbranched modified rosin resin: Under nitrogen protection, 5g of hydrogenated rosin glycerol ester, 15g of 2,2-dimethylolpropionic acid, and 10g of toluene diisocyanate were added, along with 0.05g of dibutyltin dilaurate, and the mixture was reacted at 85℃ for 5h; then 4g of trimethylolpropane was added, and the mixture was reacted at 95℃ for 3h; the temperature was lowered to 70℃, and 6g of hydroxyethyl methacrylate was added, and the mixture was reacted for 1h; finally, the temperature was lowered to 50℃, and the mixture was degassed under vacuum for 30min to obtain hyperbranched modified rosin resin. Example 1

[0030] The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 45g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was stirred for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1. Example 2

[0031] The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 60g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 15g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was continued for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was continued for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1. Example 3

[0032] The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 45g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of 3-Isocyanate-propylmethyldimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was continued for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was continued for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1. Example 4

[0033] The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 45g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g ethyl methacrylate was added, and the reaction was continued for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was continued for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1. Example 5

[0034] The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 45g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) 15g silane-terminated polyether-modified polyurethane prepolymer was added, and the reaction was stirred for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1.

[0035] Comparative Example 1 The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 60g of polycaprolactone diol and 30g of polytetramethylene ether diol respectively and remove water under vacuum at 110℃ for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Preparation Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120℃ and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100℃ and under absolute pressure ≤100Pa, stir and react under vacuum for 1h. (2) Cool down to 85℃ and add 4g of diisocyanate. 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was stirred for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1.

[0036] Comparative Example 2 The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 60g of poly(propylene adipate glycol) and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of diisocyanate. 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was stirred for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1.

[0037] Comparative Example 3 The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 75g of poly(propylene adipate) glycol and 15g of polycaprolactone glycol respectively, remove water under vacuum at 110°C for 1h, release the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010, then raise the temperature to 120°C and dehydrate under vacuum for 90min; then add 6g of diisocyanate, and under nitrogen atmosphere, adjust the temperature to 100°C and under absolute pressure ≤100Pa, stir and react under vacuum for 1h; (2) cool down to 85°C and add 4g of 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was stirred for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1.

[0038] Comparative Example 4 The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 45g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110℃ for 1h. After removing the vacuum, stir and add 5g of rosin resin and 0.4g of antioxidant 1010. Then raise the temperature to 120℃ and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100℃ and under absolute pressure ≤100Pa, stir and react under vacuum for 1h. (2) Cool down to 85℃ and add 4g of rosin resin and 5g of antioxidant 1010. 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) the system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) 15g methoxy-terminated polyether modified silane polymer was added, and the reaction was stirred for 1h; (5) under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1.

[0039] Comparative Example 5 The preparation steps for the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive are as follows: (1) Take 45g of poly(propylene adipate glycol), 15g of polycaprolactone glycol, and 30g of polytetramethylene ether glycol respectively and remove water under vacuum at 110°C for 1h. After removing the vacuum, stir and add 5g of hyperbranched modified rosin resin prepared in Example 1 and 0.4g of antioxidant 1010. Then raise the temperature to 120°C and dehydrate under vacuum for 90min. Then add 6g of diisocyanate. Under nitrogen atmosphere, adjust the temperature to 100°C and stir under vacuum for 1h under absolute pressure ≤100Pa. (2) Cool down to 85°C and add 4g of 3-Isocyanate-propyltrimethoxysilane and 0.01g bismuth isooctanoate were stirred and reacted for 2h; (3) The system was further cooled to 75℃, 3g isocyanate isocyanate was added, and the reaction was stirred for 0.5h; (4) Under light-protected conditions, the temperature was lowered to 50℃, 0.5g vinyltrimethoxysilane, 2g photoinitiator and 0.5g dibutyltin dilaurate were added, and the reaction was continued for 60min; a rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive was obtained; wherein, the photoinitiator was photoinitiator 1173 and photoinitiator TPO-L with a mass ratio of 2:1.

[0040] The rapid-positioning, pressure-free, silane-modified UV-curable polyurethane hot melt adhesive prepared in the examples and comparative examples was applied at 110°C using a dispensing machine to a polycarbonate substrate with a bonding area of ​​2*25mm. Simultaneously with the adhesive line application, a 365nm UV-LED light source (85%, approximately 1000mW) was turned on to irradiate the freshly applied adhesive line (irradiation energy 6000mJ / cm²). 2 The moisture curing conditions were 25℃ and 50%RH. The samples were stretched along the shear direction at a speed of 5 mm / min using a tensile testing machine, and the shear strength of the polycarbonate substrate was measured after 7 min and 2 h of bonding. The results are shown in Table 1 below. Table 1 Performance Test Results

[0041] As shown in Table 1, the rapid positioning pressure-free silane-modified UV moisture dual-curing polyurethane hot melt adhesive obtained in the above embodiments adopts a process of simultaneous dispensing and UV curing, which enables the adhesive to form a higher initial bonding strength in a short time, meeting the process assembly requirements. It does not require pressure holding and can proceed to subsequent assembly processes, avoiding the pressure holding stage of traditional PUR hot melt adhesives. The final bonding strength is also higher, which together ensures the high reliability and high efficiency of the adhesive in precision scenarios such as narrow bezels.

[0042] Comparative Examples 1-2 and 1-4 show that by using crystalline and amorphous polyester polyols and polyether polyols of different molecular weights in the proportions disclosed in this application, a dense three-dimensional polyurethane network is formed after crosslinking with isocyanate, strengthening the interfacial bonding force and thus improving the shear strength, thereby enhancing the overall adhesive performance of the polyurethane adhesive. The functional groups within the hyperbranched structure can interact with the aforementioned polyurethane matrix. Its hyperbranched structure can improve the density and stability of the matrix polyurethane network, further strengthening the interfacial bonding force, enhancing cohesive strength, and increasing shear strength, thus meeting the requirements of narrow-frame applications.

[0043] Comparing Examples 3-5 and Comparative Example 5, it can be seen that the -NCO end of isocyanate-based trimethoxysilane can react with the -OH end of the prepolymer to form a stable urethane bond, firmly attaching the -Si(OCH3)3 group to the end of the polymer chain. The moisture curing mechanism changes from the bubble-generating -NCO route to the bubble-free siloxane route, avoiding the presence of micropores inside the cured colloid that affect the strength, thereby improving the shear strength. Among them, 3-isocyanate-based propyltrimethoxysilane can react efficiently with hydroxyl groups, resulting in greater molecular flexibility. After end-capping, it can further improve the toughness of the adhesive layer. The flexible combination with the MS-modified silane polymer and the uniform end-capping, with only methanol released and no gas released during moisture curing, further improves the shear strength.

[0044] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A rapid-positioning, pressure-free, silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive, characterized in that: The product comprises the following components in parts by weight: 10-50 parts of amorphous polyester polyol, 5-25 parts of crystalline polyester polyol, 5-50 parts of amorphous polyether polyol, 1-8 parts of hyperbranched modified rosin resin, 0.01-0.2 parts of catalyst, 1-10 parts of isocyanate, 1-50 parts of MS modified silane polymer, 0.1-10 parts of acrylate monomer, 0.5-5 parts of photoinitiator, 1-6 parts of siloxane end-capping agent, 0.2-1 part of organotin catalyst, 0.2-2 parts of vinyltrimethoxysilane, and 0.1-1 part of antioxidant.

2. The rapid positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The amorphous polyester polyol is polypropylene adipate diol with a molecular weight of 1000-5000; the crystalline polyester polyol is polycaprolactone diol with a molecular weight of 1000-5000; and the amorphous polyether polyol is polytetramethylene ether diol with a molecular weight of 1000-2000.

3. The rapid positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The preparation method of the hyperbranched modified rosin resin includes: under nitrogen protection, taking hydrogenated rosin glycerol ester, 2,2-dimethylolpropionic acid, and toluene diisocyanate, adding dibutyltin dilaurate, and reacting at 70-85℃ for 3-5 hours; adding trimethylolpropane, and reacting at 90-100℃ for 2-5 hours; cooling to 60-70℃, adding hydroxyethyl methacrylate, and reacting for 1-3 hours; cooling to 40-50℃ and degassing under vacuum to obtain hyperbranched modified rosin resin.

4. The rapid positioning, pressure-free, silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The siloxane end-capping agent is one or more of isocyanate-trimethoxysilane, isocyanate-triethoxysilane, amino-trimethoxysilane, isocyanate-methyldimethoxysilane, and bis(3-trimethoxysilylpropyl)amine.

5. The rapid positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The isocyanate is a diisocyanate.

6. The rapid positioning, pressure-free, silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive according to claim 1, characterized in that: One or more of the following: organobismuth, organotin, organosilver, organoaluminum, organotitanium, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

7. The rapid positioning, pressure-free, silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The acrylate monomer is one or both of isocyanate methacrylate and isocyanate ethyl acrylate.

8. The rapid positioning, pressure-free, silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The MS-modified silane polymer is one or both of methoxy-terminated polyether-modified silane polymers and ethoxy-terminated polyether-modified silane polymers.

9. The rapid positioning, pressure-free, silane-modified UV moisture-curing dual-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The photoinitiator is one or more of 1173, 189, TPO-L, 184, TPO, MBF, 907, and 659.

10. A method for preparing the rapid positioning, pressure-free, silane-modified UV moisture-curing polyurethane hot melt adhesive according to any one of claims 1-9, characterized in that: The steps include: (1) Take amorphous polyester polyol, crystalline polyester polyol and amorphous polyether polyol respectively and remove water under vacuum at 100-120℃ for 0.5-1h. Remove the vacuum, stir and add hyperbranched modified rosin resin and antioxidant, then raise the temperature to 120-130℃ and dehydrate under vacuum for 60-90min; then add isocyanate, and under nitrogen atmosphere, adjust the temperature to 80-110℃ and react under vacuum with stirring for 1-3h under absolute pressure ≤100Pa; (2) Cool down to 75-85℃ and add Add siloxane end-capping agent and catalyst, and stir for 1-3 hours; (3) Adjust the system temperature to 60-80℃, add acrylate monomer, and continue stirring for 0.5-1 hours; (4) Add MS modified silane polymer, and continue stirring for 0.5 hours; (5) Under light-protected conditions, cool down to 50-60℃, add MS modified silane polymer, vinyltrimethoxysilane, photoinitiator and organotin catalyst, and continue stirring for 20-60 minutes; to obtain a rapid positioning pressure-free silane modified UV moisture dual-curing polyurethane hot melt adhesive.

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