High wet strength hot melt adhesive and method and apparatus for making same

Abstract

The application provides a high-wet-strength hot melt adhesive and a preparation method and device thereof, relates to the technical field of adhesives, and the preparation raw materials of the hot melt adhesive include, in terms of weight parts, 25-32 parts of rubber polymer, 40-48 parts of tackifying resin, 14-20 parts of rubber oil, 3-6 parts of polyolefin, 0.5-1.2 parts of coupling agent and 0.3-0.8 parts of antioxidant; the preparation method first forms a premixed carrier with the rubber oil and the antioxidant, adds the rubber polymer, the tackifying resin and the polyolefin under the protection of argon, realizes uniform mixing and deep devolatilization through multi-stage temperature control, variable-speed stirring and stepwise vacuum dewatering, finally adds the rubber oil and the coupling agent, completes the coupling reaction under low temperature and high vacuum, and filters the discharge; the hot melt adhesive can still maintain high bonding strength on the surface of condensed water, effectively solves the bonding force attenuation problem of ordinary hot melt adhesives in a high-wet environment, and is particularly suitable for humid occasions such as cold-drink packaging.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and in particular to a high wet strength hot melt adhesive and its preparation method and apparatus. Background Technology

[0002] Hot melt adhesives are widely used in labeling within the packaging industry, but they are prone to adhesion failure in high-humidity environments. For example, when labeling refrigerated beverage bottles, condensation quickly forms on the surface after the bottle is removed from its low-temperature environment, creating a continuous water film. Ordinary hot melt adhesives struggle to effectively wet and penetrate this film, leading to a significant decrease in label adhesion and resulting in label lifting or detachment. Existing technologies often add plasticizers to improve initial tack, but this sacrifices the adhesive's cohesive strength and heat resistance. While hydrophobic resins can delay water erosion, they often result in poor process compatibility, and high-temperature preparation processes can easily cause component degradation or coupling agent hydrolysis. Furthermore, conventional hot melt adhesive preparation equipment lacks sufficient precision in controlling temperature, viscosity, vacuum, and oxygen content, making it difficult to achieve uniform mixing and deep dehydration of materials. Residual moisture further exacerbates performance degradation in high-humidity environments. Using unsuitable coupling agents or employing overly homogeneous rubber polymers can also lead to a significant decrease in high-humidity adhesive strength. Therefore, there is an urgent need to develop a high-humidity-strength hot melt adhesive that combines suitable component formulation with a precise preparation process to address the insufficient adhesion reliability of existing technologies in high-humidity environments. Summary of the Invention

[0003] The purpose of this invention is to provide a high-humidity-strength hot melt adhesive and its preparation method and apparatus, to solve the problems of ordinary hot melt adhesives in high-humidity environments (such as the condensate surface of refrigerated beverage packaging) failing to effectively wet and penetrate the water film, resulting in significant attenuation of adhesion, and the degradation of components, hydrolysis of coupling agents, or incomplete dehydration caused by inaccurate temperature and vacuum control in conventional preparation processes. These problems lead to insufficient adhesion reliability and poor performance consistency of hot melt adhesive products under high humidity conditions, making it difficult to meet the stringent requirements of humid application scenarios. The specific technical solution of this invention is as follows: This invention provides a high wet strength hot melt adhesive, the raw materials for which include rubber polymer, tackifying resin, rubber oil, polyolefin, coupling agent and antioxidant.

[0004] Furthermore, the raw materials for preparing high wet strength hot melt adhesive include, by weight, 25-35 parts rubber polymer, 40-55 parts tackifying resin, 12-20 parts rubber oil, 3-10 parts polyolefin, 0.5-2 parts coupling agent and 0.3-1.5 parts antioxidant.

[0005] Furthermore, the rubber polymer includes styrene-isoprene-styrene block copolymer and hydrogenated styrene-ethylene / butene-styrene, the tackifying resin includes maleic anhydride-modified C5 petroleum resin and fully hydrogenated C9 petroleum resin, the rubber oil is naphthenic oil, the polyolefin is maleic anhydride-grafted polybutadiene, the coupling agent includes γ-aminopropyltriethoxysilane and octadecyltrimethoxysilane, and the antioxidant includes pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite.

[0006] Furthermore, the styrene-isoprene-styrene block copolymer is compounded with hydrogenated styrene-ethylene / butene-styrene (SEBS) at a mass ratio of 5:1, the maleic anhydride-modified C5 petroleum resin is compounded with fully hydrogenated C9 petroleum resin at a mass ratio of 3:1, the γ-aminopropyltriethoxysilane is compounded with octadecyltrimethoxysilane at a mass ratio of 1:2, and the antioxidant is a compound of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite at a mass ratio of 1:1.

[0007] Furthermore, the preparation method of the high wet strength hot melt adhesive includes heating rubber oil and antioxidant under inert gas protection, mixing and stirring to form a premixed carrier, adding rubber polymer to the premixed carrier, heating and stirring to obtain matrix A; adding tackifying resin and polyolefin to matrix A, heating and stirring, adding rubber oil and coupling agent and stirring, keeping warm and filtering, cooling and molding to obtain high wet strength hot melt adhesive.

[0008] Further, the rubber oil and antioxidant are heated to 80-100℃ under inert gas protection and mixed at a stirring speed of 150-200 rpm for 10-15 minutes to form a premixed carrier; the rubber polymer is added to the premixed carrier, the temperature is raised to 120-130℃, and the mixture is stirred at a stirring speed of 250-300 rpm under a vacuum of -0.05 to -0.08 MPa for 20-30 minutes to obtain matrix A.

[0009] Further, tackifying resin and polyolefin are added to matrix A, the temperature is raised to 140-150℃, and the mixture is stirred and dispersed at a stirring speed of 300-400 rpm under a vacuum of -0.07 to -0.09 MPa for 30-40 minutes.

[0010] Further, add rubber oil and coupling agent, and stir at 120-150 rpm for 15-20 minutes at 100-110℃ and a vacuum of -0.06 to -0.085 MPa.

[0011] Furthermore, after adding rubber oil and coupling agent and stirring, a deep dehydration and devolatilization step is also included: the vacuum degree is increased to -0.085 to -0.095 MPa, the temperature is raised to 145-155℃, and dehydration and devolatilization are carried out for 20-30 minutes with a stirring speed of 80-100 rpm; filtration is carried out under a heat preservation pressure of 0.3-0.4 MPa, and the mixture is injected into a sealed container purged with inert gas for cooling and molding; the inert gas is argon.

[0012] The present invention also provides a preparation apparatus for preparing the high wet strength hot melt adhesive, comprising an intelligent temperature control module, a dynamic viscosity sensing module, a vacuum dehydration module, and an anti-oxidation encapsulation module; The intelligent temperature control module includes three independent heating jackets surrounding the reactor, multiple temperature sensors, and a main control PLC, used to realize gradient heating and regional temperature control. The dynamic viscosity sensing module is integrated on the stirring shaft to monitor the melt viscosity and material homogeneity in real time, and is linked with the stirring motor and intelligent temperature control module. The vacuum dehydration module includes a vacuum pump set, a cold trap, and a moisture analyzer, which are used to create a high vacuum environment and monitor the moisture content online. The anti-oxidation packaging module includes an inert gas protection subsystem and a sealed filter discharge subsystem, which are used to completely isolate oxygen throughout the process.

[0013] The beneficial effects of this invention are as follows: The SIS / SEBS compound rubber system involved in this invention imparts good initial tack and cohesive strength to the colloid, while the saturated molecular chain structure of SEBS can improve its moisture resistance; the combination of maleic anhydride modified C5 petroleum resin and hydrogenated C9 petroleum resin not only provides excellent bonding performance, but its polar functional groups and chemical stability are also more conducive to forming effective wetting at the humid interface; the compound coupling agent of γ-aminopropyltriethoxysilane and octadecyltrimethoxysilane respectively plays the role of chemical bonding with inorganic substrates (such as glass bottles) and the hydrophobic guiding function of long-chain alkyl groups; and the addition of polyolefin further enhances the cohesiveness and heat resistance of the colloid, preventing cohesive destruction in high humidity environments. More importantly, the dedicated preparation device ensures that the above components are uniformly dispersed, fully reacted, and not degraded or hydrolyzed during the preparation process through the coordinated operation of intelligent temperature control, dynamic viscosity sensing, step-by-step vacuum dehydration, and full-process anti-oxidation protection. This fully transforms the synergistic potential of the formula design into the final stable and reliable high wet bonding strength of the product, effectively solving the problem of label curling and falling off due to condensation in scenarios such as refrigerated beverage packaging.

[0014] The high wet strength of the hot melt adhesive involved in this invention mainly relies on the synergistic mechanism of "interfacial water film replacement" and "interfacial chemical anchoring". The saturated structure in the SEBS molecular chain makes it more hydrophobic than SIS, which helps to displace the water film on the substrate surface. The long-chain alkyl group of octadecyltrimethoxysilane also enhances the overall hydrophobicity of the colloid and promotes the contact between the colloid and the wet substrate. Meanwhile, the silanol groups generated from the hydrolysis of the alkoxy groups in γ-aminopropyltriethoxysilane can form strong Si-O-Si covalent bonds with the hydroxyl groups on the surfaces of substrates such as glass and metal, achieving "chemical anchoring." This bonding effect is far stronger than physical adsorption and can effectively resist the erosion and damage of moisture. At the process level, the core principle of the preparation device is to ensure the effective function of each component by precisely controlling the reaction conditions: intelligent temperature control and variable speed stirring ensure uniform melting and dispersion of materials, avoiding local overheating and degradation; high vacuum dehydration thoroughly removes any residual moisture in the raw materials and reaction, preventing it from interfering with the hydrolysis-condensation reaction of the coupling agent and forming weaknesses in the finished product; inert gas protection prevents the polymer from oxidative embrittlement at high temperatures. These measures together ensure that the designed functional groups are well preserved and function, thus enabling the hot melt adhesive to exhibit stable and durable adhesion in real high-humidity environments. Detailed Implementation

[0015] The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] The rubber polymer involved in this invention is a blend of styrene-isoprene-styrene block copolymer (SIS) and hydrogenated styrene-ethylene / butene-styrene (SEBS) in a mass ratio of 5:1. The tackifying resin is a blend of maleic anhydride-modified C5 petroleum resin and fully hydrogenated C9 petroleum resin in a mass ratio of 3:1. The rubber oil is a naphthenic oil with a kinematic viscosity of 90 cSt at 40°C. The polyolefin is maleic anhydride-grafted polybutadiene with a grafting rate of 2.0%. The coupling agent is a blend of γ-aminopropyltriethoxysilane (KH-550) and octadecyltrimethoxysilane in a mass ratio of 1:2. The antioxidant is a blend of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010) and tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168) in a mass ratio of 1:1.

[0017] The styrene-isoprene-styrene block copolymer is Kraton's D1116, the hydrogenated styrene-ethylene / butene-styrene is Kraton's G1650, the maleic anhydride modified C5 petroleum resin is ExxonMobil's Escorez™ 1102, the fully hydrogenated C9 petroleum resin is Eastman's Regalite™ R1090, the naphthenic oil is Nyflex™ 222B from Nynas, and the maleic anhydride grafted polybutadiene is Kraton's FG1901X.

[0018] Example 1

[0019] This embodiment provides a high wet strength hot melt adhesive. The raw materials for preparing the high wet strength hot melt adhesive include, by weight, 32 parts rubber polymer, 48 parts tackifying resin, 16 parts rubber oil, 6 parts polyolefin, 1.2 parts coupling agent and 0.8 parts antioxidant.

[0020] The rubber polymer is composed of 26.7 parts SIS and 5.3 parts SEBS.

[0021] The tackifying resin is composed of 36 parts maleic anhydride-modified C5 petroleum resin and 12 parts hydrogenated C9 petroleum resin.

[0022] The coupling agent is 0.4 parts of γ-aminopropyltriethoxysilane and 0.8 parts of octadecyltrimethoxysilane.

[0023] The antioxidants are 0.4 parts antioxidant 1010 and 0.4 parts antioxidant 168.

[0024] This embodiment also provides a method for preparing a high-wet-strength hot melt adhesive. The method is carried out in a reaction apparatus equipped with intelligent temperature control, high-shear stirring, high vacuum, and inert gas protection systems. The preparation method includes the following steps: Add 9.6 parts by weight of rubber oil and 0.8 parts by weight of antioxidant. Under argon atmosphere protection, heat to 100°C and mix at a stirring speed of 200 rpm for 15 minutes to form a premixed carrier. Add 32 parts by weight of rubber polymer, heat to 130°C, increase the stirring speed to 300 rpm, and stir and react for 30 minutes at 130°C and -0.08 MPa vacuum to obtain matrix A. Add 48 parts of tackifying resin and 6 parts of polyolefin to matrix A, raise the temperature to 150°C, stir at 400 rpm, and disperse for 40 minutes at 150°C and -0.09 MPa vacuum. Add 6.4 parts of rubber oil and 1.2 parts of coupling agent, stir at 150 rpm for 20 minutes at 110°C and -0.085 MPa vacuum, raise the vacuum to -0.095 MPa, and stir at 100 rpm for 30 minutes at 155°C and high vacuum for deep dehydration and devolatilization. Filter under a heat preservation pressure of 0.4 MPa, inject into a sealed container purged with argon, and cool to form a high wet strength hot melt adhesive.

[0025] Example 2

[0026] This embodiment provides a high wet strength hot melt adhesive. The raw materials for preparing the high wet strength hot melt adhesive include, by weight, 25 parts rubber polymer, 40 parts tackifying resin, 20 parts rubber oil, 3 parts polyolefin, 0.5 parts coupling agent and 0.3 parts antioxidant.

[0027] The rubber polymer is composed of 18.75 parts SIS and 6.25 parts SEBS.

[0028] The tackifying resin is 30 parts of unmodified C5 petroleum resin and 10 parts of ordinary C9 petroleum resin.

[0029] The coupling agent is 0.5 parts of a single γ-aminopropyltriethoxysilane.

[0030] The antioxidant is 0.3 parts of antioxidant 1010.

[0031] This embodiment also provides a method for preparing a high-wet-strength hot melt adhesive. The method is carried out in a reaction apparatus equipped with intelligent temperature control, high-shear stirring, high vacuum, and inert gas protection systems. The preparation method includes the following steps: Add 20 parts by weight of rubber oil and 0.3 parts by weight of antioxidant. Under argon atmosphere protection, heat to 80°C and mix for 10 minutes with stirring speed of 150 rpm. Add 25 parts by weight of rubber polymer, raise the temperature to 120°C, increase the stirring speed to 250 rpm, and stir for 20 minutes at 120°C and -0.05 MPa vacuum to obtain matrix A. Add 40 parts of tackifying resin and 3 parts of polyolefin to matrix A, raise the temperature to 140°C, stir at 300 rpm, and disperse for 30 minutes at 140°C and -0.07 MPa vacuum. Add 0.5 parts of coupling agent, stir at 120 rpm for 15 minutes at 100°C and -0.06 MPa vacuum, raise the vacuum to -0.085 MPa, and stir at 80 rpm for 20 minutes at 145°C and high vacuum for dehydration and devolatilization. Filter under a heat preservation pressure of 0.3 MPa, inject into a sealed container purged with argon, and cool to form a high wet strength hot melt adhesive.

[0032] Example 3

[0033] This embodiment provides a high wet strength hot melt adhesive. The raw materials for preparing the high wet strength hot melt adhesive include, by weight, 28 parts rubber polymer, 45 parts tackifying resin, 14 parts rubber oil, 5 parts polyolefin, 0.8 parts coupling agent and 0.5 parts antioxidant.

[0034] The rubber polymer is composed of 21 parts SIS and 7 parts SEBS.

[0035] The tackifying resin is composed of 33.75 parts hydrogenated C5 petroleum resin and 11.25 parts hydrogenated C9 petroleum resin.

[0036] The coupling agent is 0.27 parts of γ-aminopropyltriethoxysilane and 0.53 parts of octadecyltrimethoxysilane.

[0037] The antioxidants are 0.25 parts of antioxidant 1010 and 0.25 parts of antioxidant 168.

[0038] This embodiment also provides a method for preparing a high-wet-strength hot melt adhesive. The method is carried out in a reaction apparatus equipped with intelligent temperature control, high-shear stirring, high vacuum, and inert gas protection systems. The preparation method includes the following steps: Add 8.4 parts by weight of rubber oil and 0.5 parts by weight of antioxidant. Under argon atmosphere protection, heat to 95°C and mix at a stirring speed of 180 rpm for 12 minutes to form a premixed carrier. Add 28 parts by weight of rubber polymer, heat to 125°C, increase the stirring speed to 280 rpm, and stir for 25 minutes at 125°C and -0.07 MPa vacuum to obtain matrix A. Add 45 parts of tackifying resin and 5 parts of polyolefin to matrix A, raise the temperature to 145°C, and stir at 350 rpm. Disperse the mixture for 35 minutes at 145°C and -0.085 MPa vacuum. Add 5.6 parts of rubber oil and 0.8 parts of coupling agent, and stir at 140 rpm for 18 minutes at 105°C and -0.075 MPa vacuum. Increase the vacuum to -0.09 MPa and stir at 90 rpm for 25 minutes at 150°C and high vacuum for deep dehydration and devolatilization. Filter the mixture under a heat preservation pressure of 0.35 MPa and inject it into a sealed container purged with argon gas. Cool and solidify to obtain a high wet strength hot melt adhesive.

[0039] Example 4

[0040] This embodiment provides an apparatus for preparing high-wet-strength hot melt adhesive, which is used to implement the high-wet-strength hot melt adhesive preparation method described in the embodiment. Through the coordinated control of four functional modules, this apparatus achieves precise regulation of key parameters such as temperature, viscosity, vacuum degree, and oxidation protection during the preparation process, ensuring that the final product maintains excellent bonding strength even on condensate surfaces.

[0041] The preparation device includes an intelligent temperature control module, a dynamic viscosity sensing module, a vacuum dehydration module, and an anti-oxidation packaging module.

[0042] The intelligent temperature control module includes three independent heating jackets surrounding the reactor, six high-precision thermocouple temperature sensors, and a main control PLC. The three heating jackets correspond to the upper, middle, and lower regions of the reactor body, enabling gradient heating and precise regional temperature control. The six temperature sensors monitor the material temperature at different heights and depths within the reactor in real time and feed the data back to the PLC. Based on a preset process curve, the PLC dynamically adjusts the heating power and cooling water flow of each jacket, achieving precise heating, holding, and cooling control across multiple stages.

[0043] The dynamic viscosity sensing module is integrated onto the stirring shaft and includes an online rotational viscometer and an ultrasonic probe. The online rotational viscometer monitors the viscosity changes of the melt in real time during stirring, while the ultrasonic probe detects material homogeneity and any unmelted particles. This module works in conjunction with the stirring motor and intelligent temperature control module. When the viscosity deviates from the preset process window, the system can automatically fine-tune the stirring rate (within the range of 100-400 rpm) or adjust the temperature setting to ensure that the material is in its optimal rheological state during critical steps (such as resin dispersion and coupling agent reaction stages), thereby guaranteeing the homogeneity of component mixing.

[0044] The vacuum dehydration module consists of a high-speed rotary vane vacuum pump, a Roots booster pump, a cryogenic cold trap, and a precision moisture analyzer. The vacuum pump unit can reduce the pressure inside the reactor from atmospheric pressure to below -0.095 MPa within 10 minutes. The cryogenic cold trap is used for efficient condensation and capture of released small molecule volatiles and water vapor. The precision moisture analyzer monitors the moisture content in the vapor phase at the top of the reactor online using infrared spectroscopy and provides real-time data feedback. When the detected moisture content is below the target value of 0.02%, the system can automatically switch to the next process or maintain a high vacuum state to ensure thorough completion of deep dehydration.

[0045] The anti-oxidation encapsulation module is used throughout the entire preparation process, including an inert gas protection subsystem and a sealed filtration and discharge subsystem. The inert gas protection subsystem consists of an argon source, a mass flow controller, and multiple distribution heads to ensure that a slightly positive pressure argon atmosphere is maintained inside the reactor during feeding, reaction, and discharge. The sealed filtration and discharge subsystem has an insulated discharge port that is directly connected to a 200-mesh stainless steel pressure filter. The filter outlet is directly connected to a sealed finished product receiving tank that has been purged with argon, achieving complete oxygen isolation from reaction, filtration, to encapsulation.

[0046] The relevance of the device's workflow to the product in this embodiment includes: When preparing high-wet-strength hot melt adhesive using this device, the intelligent temperature control module ensures complete polymer melting and uniform resin dispersion, and precisely cools the system before adding the coupling agent, effectively preventing high-temperature hydrolysis failure of the coupling agent. The dynamic viscosity sensing module ensures material uniformity under high temperature and high shear, laying the foundation for subsequent reactions. The deep vacuum environment and precise moisture control created by the vacuum dehydration module reduce the moisture content of the final product to an extremely low level, which is crucial for maintaining product performance stability in high-humidity environments. The anti-oxidation encapsulation module prevents the polymer from undergoing thermo-oxidative degradation at high temperatures throughout the process, protecting active ingredients such as the coupling agent.

[0047] This device, through the coordinated operation of the aforementioned modules, precisely, stably, and repeatably achieves the optimal process described in the embodiments, thereby ensuring that the prepared hot melt adhesive product possesses a dual mechanism of "interfacial water film replacement" and "chemical anchoring." Even for glass containers where condensation occurs on the surface after refrigeration, the final product maintains excellent bonding strength under high humidity conditions, effectively solving the industry problem of adhesive strength decay of ordinary hot melt adhesives under high humidity. This invention is particularly suitable for applications requiring strong adhesion in humid environments, such as labeling and sealing of refrigerated beverage packaging.

[0048] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 lacks an equal part by weight of polyolefin, while the rest is the same as Example 1.

[0049] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the coupling agent in Comparative Example 2 is replaced with an equal amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, while the rest is the same as in Example 1.

[0050] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the complex system of SIS and SEBS (5:1) is replaced with a single SIS with the same total number of parts. All other contents are the same as Example 1.

[0051] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the complex system of SIS and SEBS (5:1) is replaced with a single SEBS with the same total number of parts. All other contents are the same as Example 1.

[0052] Performance testing All embodiments and comparative examples underwent 180° peel strength testing, condensation interface bond strength testing, high humidity strength retention testing (to assess durability), and thermal stability testing. The specific methods are as follows: Following standard GB / T 2790 "Test Method for 180° Peel Strength of Adhesives - Flexible Materials vs. Rigid Materials," molten adhesive was applied to a polyester film at 150°C, with a layer thickness of 50 μm. This film was immediately bonded to a standard stainless steel plate and held under 0.4 MPa pressure for 30 seconds. The film was then placed in a standard environment at 23°C and 50±5% relative humidity for 24 hours. A 180° peel test was performed using a universal testing machine at a rate of 300 mm / min. Following standard GB / T 7124 "Determination of Tensile Shear Strength of Adhesives," the joint preparation conditions were specially designed to simulate a high humidity condensation environment. A standard glass specimen (100 mm × 25 mm) was placed in a 5°C environment for 4 hours, then removed and left to stand for 2 minutes in an environment of 23°C and 90% relative humidity to allow a uniform condensation film to form on the glass surface (the amount of water film adhesion was confirmed to be approximately 3 ± 0.5 g / m² by weighing). The molten colloid (150°C) was immediately applied to the bonding surface of one of the glass specimens, overlapping it with the other glass specimen with an overlap area of ​​25 mm × 12.5 mm, and held under pressure at 0.2 MPa for 10 seconds. After curing the prepared samples in an environment of 40℃ and 90%RH for 24 hours, their tensile shear strength was measured in an environment of 23℃ and 50%RH. 180° peel strength test samples were prepared according to the above method. The samples were placed in a constant temperature and humidity chamber at 40℃ and 90% relative humidity, and their initial peel strength (S0) before placement and their peel strength (S1) after 720 hours (30 days) were measured. The strength retention rate (%) = (S1 / S0) × 100%. Using a rotational viscometer, the change in colloid melt viscosity over time was measured at a constant temperature of 155℃. An appropriate amount of sample was placed in the viscometer test cylinder, preheated at 155℃ for 5 minutes, and then its initial viscosity (η0) was measured at a fixed rotation speed. The viscosity was measured every 30 minutes while maintaining the temperature, and the viscosity (η2) was recorded after 2 hours. The viscosity change rate (%) = [(η2 - η0 / η0] × 100%. The smaller the change rate, the better the thermal stability. The results are shown in Table 1.

[0053] Table 1 Sample number 180° peel strength (N / mm, 23℃, 50%RH) Condensate interfacial bond strength (MPa) High humidity strength retention rate (%, 720 hours) Thermal stability (viscosity change rate at 155°C for 2 hours, %) Example 1 12.5 2.1 92 +2.8 Example 2 9.1 1.3 78 +5.5 Example 3 11.3 1.8 85 +4.0 Comparative Example 1 8.5 0.8 58 +8.0 Comparative Example 2 7.0 0.4 45 +12.0 Comparative Example 3 10.5 1.0 65 +7.2 Comparative Example 4 8.8 0.9 70 +4.5 As shown in Table 1, the examples utilize a SIS / SEBS composite elastomer as the basic polymer backbone, combined with a specific high softening point tackifying resin, maleic anhydride-grafted polyolefin, and amino / long-chain alkylsilane composite coupling agent, and supplemented by precise staged temperature control and vacuum dehydration processes. This constructs a synergistic system that combines excellent initial tack, high cohesive strength, effective hydrophobic barrier, and interfacial chemical anchoring ability. This system enables the products of the examples, especially the most preferred example 1, to quickly dissipate the water film at the condensate interface and form a strong chemical bond and physical anchoring, thus exhibiting much higher condensate interface bonding strength and high wet durability than the comparative examples. Comparative example 1 lacks polyolefin, resulting in insufficient hydrophobicity and cohesive strength. Comparative example 2 suffers from high-temperature deactivation due to improper type and timing of coupling agent addition, leading to the failure of interfacial anchoring function. Comparative examples 3 and 4, due to the use of a single polymer (only SIS or SEBS, respectively), cannot simultaneously achieve initial tack and heat creep resistance or high wet strength.

[0054] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A high wet strength hot melt adhesive, characterized in that, The raw materials for preparing high wet strength hot melt adhesives include rubber polymers, tackifying resins, rubber oils, polyolefins, coupling agents, and antioxidants.

2. The high wet strength hot melt adhesive as described in claim 1, characterized in that, The raw materials for preparing high wet strength hot melt adhesive include, by weight, 25-35 parts rubber polymer, 40-55 parts tackifying resin, 12-20 parts rubber oil, 3-10 parts polyolefin, 0.5-2 parts coupling agent and 0.3-1.5 parts antioxidant.

3. The high wet strength hot melt adhesive as described in claim 1, characterized in that, The rubber polymers include styrene-isoprene-styrene block copolymers and hydrogenated styrene-ethylene / butene-styrene; the tackifying resins include maleic anhydride-modified C5 petroleum resin and fully hydrogenated C9 petroleum resin; the rubber oil is a naphthenic oil; the polyolefin is maleic anhydride-grafted polybutadiene; the coupling agents include γ-aminopropyltriethoxysilane and octadecyltrimethoxysilane; and the antioxidants include pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite.

4. The high wet strength hot melt adhesive as described in claim 3, characterized in that, The styrene-isoprene-styrene block copolymer is compounded with hydrogenated styrene-ethylene / butene-styrene (SEBS) at a mass ratio of 5:1; maleic anhydride-modified C5 petroleum resin is compounded with fully hydrogenated C9 petroleum resin at a mass ratio of 3:1; γ-aminopropyltriethoxysilane is compounded with octadecyltrimethoxysilane at a mass ratio of 1:2; and the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite at a mass ratio of 1:

1.

5. A method for preparing a high wet strength hot melt adhesive as described in claim 1, characterized in that, The process includes heating rubber oil and antioxidant under an inert gas atmosphere, mixing and stirring to form a premixed carrier, adding a rubber polymer to the premixed carrier, heating and stirring to obtain matrix A; adding tackifying resin and polyolefin to matrix A, heating and stirring, adding rubber oil and coupling agent and stirring, keeping warm and filtering, and cooling and molding to obtain a high wet strength hot melt adhesive.

6. The method for preparing high wet strength hot melt adhesive as described in claim 5, characterized in that, Rubber oil and antioxidant are heated to 80-100℃ under inert gas protection and mixed at a stirring speed of 150-200 rpm for 10-15 minutes to form a premixed carrier. Rubber polymer is added to the premixed carrier, the temperature is raised to 120-130℃, and the mixture is stirred at a stirring speed of 250-300 rpm under a vacuum of -0.05 to -0.08 MPa for 20-30 minutes to obtain matrix A.

7. The method for preparing high wet strength hot melt adhesive as described in claim 5, characterized in that, Add tackifying resin and polyolefin to matrix A, heat to 140-150℃, and stir and disperse at a stirring speed of 300-400 rpm under a vacuum of -0.07 to -0.09 MPa for 30-40 minutes.

8. The method for preparing high wet strength hot melt adhesive as described in claim 5, characterized in that, Add rubber oil and coupling agent, and stir at 120-150 rpm for 15-20 minutes at 100-110℃ and a vacuum of -0.06 to -0.085 MPa.

9. The method for preparing high wet strength hot melt adhesive as described in claim 5, characterized in that, After adding rubber oil and coupling agent and stirring, a deep dehydration and devolatilization step is also included: the vacuum degree is increased to -0.085 to -0.095 MPa, the temperature is raised to 145-155℃, and dehydration and devolatilization are carried out for 20-30 minutes with a stirring speed of 80-100 rpm; filtration is carried out under a heat preservation pressure of 0.3-0.4 MPa, and the mixture is injected into a sealed container purged with inert gas for cooling and molding; the inert gas is argon.

10. An apparatus for preparing the high wet strength hot melt adhesive according to any one of claims 1 to 4, characterized in that, It includes an intelligent temperature control module, a dynamic viscosity sensing module, a vacuum dehydration module, and an anti-oxidation packaging module; The intelligent temperature control module includes three independent heating jackets surrounding the reactor, multiple temperature sensors, and a main control PLC, used to realize gradient heating and regional temperature control. The dynamic viscosity sensing module is integrated on the stirring shaft to monitor the melt viscosity and material homogeneity in real time, and is linked with the stirring motor and intelligent temperature control module. The vacuum dehydration module includes a vacuum pump set, a cold trap, and a moisture analyzer, which are used to create a high vacuum environment and monitor the moisture content online. The anti-oxidation packaging module includes an inert gas protection subsystem and a sealed filter discharge subsystem, which are used to completely isolate oxygen throughout the process.