Low-temperature fast-sealing high-initial-adhesion box sealing hot melt adhesive and preparation method thereof

Abstract

The invention relates to the technical field of hot melt adhesives, in particular to a low-temperature quick-sealing high-initial-adhesion box sealing hot melt adhesive and a preparation method thereof. The hot melt adhesive comprises a polyolefin elastomer, wax, an ethylene-vinyl acetate copolymer, hydrogenated hydrocarbon tackifying resin and special functional tackifying phase particles. Hydrogenated hydrocarbon tackifying resin is grafted with maleic anhydride and then sequentially reacts with polyethylene glycol monomethyl ether amine, polyether monoamine and octadecane amine to prepare the particles. According to the structure, the interfacial tension of colloid on the surface of the low-temperature paperboard can be remarkably reduced, rapid spreading and permeation are realized, and meanwhile, the cohesive strength and flexibility are enhanced, so that excellent rapid sealing performance and high initial adhesion are obtained at low temperature.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, and in particular to a low-temperature fast-sealing, high initial tack hot melt adhesive for sealing boxes and its preparation method. Background Technology

[0002] Hot melt adhesives for sealing boxes are widely used in the logistics packaging field, and their performance directly affects sealing efficiency and packaging safety. Conventional hot melt adhesives are mainly composed of ethylene-vinyl acetate copolymer, tackifying resin, and waxes. At room temperature, they can melt, flow, wet the surfaces to be bonded, and solidify upon cooling to form an adhesive. However, when the ambient temperature drops to a low temperature range of 5-15℃, the performance shortcomings of these adhesives become apparent.

[0003] First, low temperatures significantly increase the melt viscosity of the hot melt adhesive system, resulting in poorer adhesive flowability. On high-speed automated sealing lines, after the adhesive is extruded from the coating head, it is difficult for it to fully level and penetrate the rough, porous fiber surface of the corrugated cardboard within the set, extremely short time. This insufficient wetting directly leads to a significant reduction in the actual contact area between the adhesive layer and the cardboard, resulting in weak interfacial forces. This manifests as the cardboard cover being easily lifted or springing back under internal tension or slight external impact after sealing, a phenomenon known as cold opening. In severe cases, separation can even occur immediately after pressing, causing production line downtime and packaging failure.

[0004] Secondly, to address the issue of insufficient initial tack at low temperatures, a common approach is to increase the application temperature of the hot melt adhesive, hoping to reduce the viscosity and improve flowability through higher heat energy. However, this approach has significant drawbacks: on the one hand, continuous high-temperature operation significantly increases energy consumption; on the other hand, excessively high temperatures can easily cause some heat-sensitive components in the hot melt adhesive (such as certain tackifying resins or polymers) to undergo thermal oxidation or thermal degradation, resulting in a darker color of the adhesive, the formation of charred particles and stringing. This not only clogs the nozzles of precision adhesive application equipment, affecting the uniformity of adhesive application, but also introduces impurities, damaging the appearance and reliability of the bond.

[0005] In addition, some technologies have attempted to enhance the interaction between colloids and paper fibers by introducing highly polar components. However, simply increasing the polarity of the system often leads to new problems such as decreased cohesive strength or poor compatibility. Hot melt adhesives with excessively high polarity may become brittle after cooling, easily cracking or even breaking when subjected to bending or impact at low temperatures, resulting in deteriorated flexibility. This brittleness not only affects the stacking and compression resistance of boxes after sealing but may also cause premature failure of the adhesive interface under stress. Therefore, how to simultaneously achieve instantaneous and rapid wetting of the paper substrate by the colloid and subsequent continuous and reliable cohesive strengthening under low-temperature conditions, while maintaining excellent processing stability and material durability, has become a critical technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a low-temperature fast-sealing high initial tack hot melt adhesive for sealing boxes and its preparation method, so as to solve the problems of existing hot melt adhesives for sealing boxes in low-temperature environments, which lead to insufficient wetting and spreading of corrugated paper fibers due to the rapid increase in melt viscosity, making it impossible to establish effective initial tack in a very short time, often resulting in adhesive failure. At the same time, increasing the application temperature to compensate for strength leads to increased energy consumption and material charring.

[0007] To achieve the above objectives, the present invention provides a low-temperature fast-sealing, high initial tack hot melt adhesive for sealing boxes, comprising, by weight parts: 600-650 parts of polyolefin elastomer; 180-200 parts of Fischer-Tropsch wax; 90-100 parts of microcrystalline wax; 200-220 parts of ethylene-vinyl acetate copolymer; 300-400 parts of hydrogenated hydrocarbon tackifying resin; and 492-552 parts of functional tackifying phase particles; wherein the functional tackifying phase particles are obtained by grafting maleic anhydride onto the hydrogenated hydrocarbon tackifying resin, followed by sequential reaction with polyethylene glycol methyl etheramine, polyether monoamine, and octadecylamine.

[0008] Preferably, it also includes 8 parts of antioxidant 1010.

[0009] Furthermore, the functional tackifying phase particles are prepared from the following raw materials in parts by mass: 1000 parts hydrogenated hydrocarbon tackifying resin, 20-30 parts maleic anhydride, 1.5-2.5 parts organic peroxide initiator, 60-100 parts polyethylene glycol methyl ether amine, 40-80 parts polyether monoamine and 15-25 parts octadecylamine.

[0010] Preferably, the organic peroxide initiator is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0011] Preferably, the polyolefin elastomer has an ethylene content of 11wt%-13wt%, a viscosity of 7400-7700 mPa·s at 190℃, a melting point of 90-110℃, and a glass transition temperature of -31±2℃.

[0012] Preferably, the hydrogenated hydrocarbon tackifying resin is a fully hydrogenated hydrocarbon resin with a ring and ball softening point of 90-110°C.

[0013] Preferably, the vinyl acetate content of the ethylene-vinyl acetate copolymer is 27wt%-29wt%, and the melt index at 190℃ / 2.16kg is 380-420g / 10min.

[0014] Preferably, the polyethylene glycol methyl etheramine is from the Sigma-Aldrich brand, product number 767565.

[0015] Preferably, the polyether monoamine is sourced from Huntsman, model JEFFAMINE M-2005.

[0016] Furthermore, the present invention also provides a method for preparing functional thickening phase particles, comprising the following steps: (1) After heating and melting the hydrogenated hydrocarbon tackifying resin under nitrogen protection, maleic anhydride is added and grafting reaction is carried out under the action of organic peroxide initiator to obtain maleic anhydride grafted modified hydrogenated hydrocarbon tackifying resin melt. (2) After the melt obtained in step (1) is devastated and cooled, polyethylene glycol methyl ether amine, polyether monoamine and octadecaneamine are added in sequence to react and obtain a functional thickening phase melt; (3) After the functional thickening phase melt obtained in step (2) is devolatilized, cooled and pulverized into granules to obtain functional thickening phase particles.

[0017] Preferably, in step (1), the reactor is purged with nitrogen under nitrogen protection, with a nitrogen flow rate of 200 mL / min and a purging time of 20 min. The hydrogenated hydrocarbon tackifying resin is heated to 160°C and stirred and melted at 200 rpm for 30 min, then heated to 190°C and held at that temperature for 10 min.

[0018] Furthermore, the present invention also provides a method for preparing a low-temperature fast-sealing high initial tack hot melt adhesive for sealing boxes, comprising the following steps: melting and mixing polyolefin elastomer, Fischer-Tropsch wax and microcrystalline wax, then adding ethylene-vinyl acetate copolymer and mixing, then adding hydrogenated hydrocarbon tackifying resin and mixing, and subsequently adding the functional tackifying phase particles and mixing to obtain a molten colloid, which is then cooled and molded to obtain the low-temperature fast-sealing high initial tack hot melt adhesive for sealing boxes.

[0019] Preferably, the polyolefin elastomer, Fischer-Tropsch wax, and microcrystalline wax are heated to 150°C and stirred at 60 rpm for 30 min. The ethylene-vinyl acetate copolymer is added in three portions at 150°C with a 10 min interval between each addition. The mixture is then heated to 160°C and stirred for another 40 min. Hydrogenated hydrocarbon tackifying resin is added and stirred for 30 min. The system is then cooled to 150°C. Functional tackifying phase particles are added in four portions at 150°C with an 8 min interval between each addition. The mixture is stirred for another 40 min. The system is then cooled to 140°C, antioxidant 1010 is added, and the mixture is stirred for 10 min. Finally, the mixture is filtered through a 120-mesh stainless steel filter while still hot and then cast and cooled to form the final product.

[0020] Furthermore, the hot melt adhesive can also be used for lap bonding or lap sealing of thermoplastic polyolefin waterproof membranes.

[0021] The beneficial effects of this invention are: To improve the reliability of low-temperature bonding, the solution involves controlled graft modification of the hydrogenated hydrocarbon tackifying resin with maleic anhydride and preferential introduction of polyethylene glycol methyl etheramine, constructing a highly polar anchoring segment on its molecular chain. This structure significantly reduces the interfacial tension of the adhesive on the surface of low-temperature corrugated cardboard, enabling the molten adhesive to spread and penetrate rapidly even at 5-15°C. This effectively overcomes the water repellency of cardboard fibers at low temperatures, creating conditions for instantaneous mechanical interlocking and physical anchoring. Consequently, effective initial adhesion is rapidly established within a short pressing time, fundamentally suppressing capping and springback phenomena.

[0022] To ensure both adhesive strength and durability, the solution further introduces long-chain polyether monoamines into the functional tackifying phase. These long, compliant segments can form effective entanglements with the matrix polymer, enhancing the cohesive strength of the adhesive film. Simultaneously, they act as stress buffers at the interface, dispersing stress caused by external loads or temperature differences and preventing early interface failure due to stress concentration. Combined with the hydrophobic octadecylamine end-capping, not only are potential instabilities caused by residual polar groups eliminated, but the compatibility of the functional tackifying phase with hydrophobic components such as polyolefin elastomers and wax phases is improved, promoting the formation of a continuous, dense adhesive film after cooling. This results in both high initial tack and excellent final adhesive strength.

[0023] To improve processing suitability and material stability, the solution employs a dual-phase strategy combining traditional tackifying resin and functional tackifying phase. The traditional tackifying resin ensures good overall compatibility and a wide processing viscosity window, effectively suppressing stringing tendencies during high-temperature coating. The functional tackifying phase is added in the mid-to-late stages of the adhesive formulation process, combined with the final addition of antioxidants. This timing design minimizes the thermal history of the functional components during high-temperature mixing, protecting their molecular structural integrity, reducing the risk of thermal decomposition and charring, and ensuring the performance stability and appearance quality of the adhesive during long-term use or repeated heating.

[0024] In addition, the low-temperature fast-sealing high initial tack hot melt adhesive described in this invention is not only suitable for sealing corrugated cardboard boxes, but also for rapid bonding and lap sealing of polyolefin substrates, especially for lap bonding of thermoplastic polyolefin waterproof membranes. Because the functional tackifying phase particles simultaneously possess polar anchoring segments and hydrophobic compatible segments, they can improve the spreading and interfacial bonding on the surface of polyolefin substrates at low temperatures, and provide higher cohesive strength and flexibility after cooling, thereby improving the peel resistance and crack resistance reliability of lap bonding. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0026] Figure 1The infrared spectrum is shown for the low-temperature fast-sealing high initial adhesion hot melt adhesive prepared in Example 1 of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0028] The hydrogenated hydrocarbon tackifying resin used in the examples and comparative examples was Synthomer's Regalite R1100 hydrogenated hydrocarbon tackifying resin (fully hydrogenated hydrocarbon resin, ring and ball softening point 100°C, melt viscosity approximately 500 cP at 160°C); the maleic anhydride used was Merck's Sigma-Aldrich brand maleic anhydride (product number M188, CAS 108-31-6, purity ≥99%); the organic peroxide initiator used was Nouryon's Trigonox 101 (chemical name 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane); the polyethylene glycol methyl ether amine used was Merck's Sigma-Aldrich brand Poly(ethylene glycol) methyl ether amine (product number 767565, average molecular weight approximately 500, CAS 80506-64-5, monofunctional amine); and the polyether monoamine used was Huntsman's JEFFAMINE. M-2005 polyether monoamine (molecular weight approximately 2000, amine hydrogen equivalent approximately 1045 g / eq, amine value 0.42 meq / g to 0.50 meq / g); the polyolefin elastomer selected is ExxonMobil Vistamaxx Performance Polymer 8380 (density 0.864 g / cm³). 3 The ethylene content is 12wt%, the viscosity at 190℃ is 7570mPa·s, the melting point is 100℃, and the glass transition temperature is -31℃. The ethylene-vinyl acetate copolymer particles used are Dow's ELVAX 210W ethylene-vinyl acetate copolymer particles (vinyl acetate content is about 28wt%, melt index is about 400g / 10min (190℃ / 2.16kg)). The wax system used is Sasol's SASOLWAX C80 Fischer-Tropsch high melting point wax (pastille form) and Sasol's MERKUR 108 microcrystalline wax (white solid block, freezing point >50℃).

[0029] Example 1: Step 1: Preheat a four-necked reactor equipped with a mechanical stirrer, temperature probe, nitrogen inlet / outlet, and vacuum port. Purge with nitrogen at 200 mL / min for 20 min. Add 1000 g of hydrogenated hydrocarbon thickening resin, heat to 160 °C, and stir at 200 rpm for 30 min to melt. Under nitrogen micro-positive pressure protection, heat the melt to 190 °C and hold for 10 min. Add 25 g of maleic anhydride in 5 portions (5 g each time, 4 min apart, 200 rpm). After the maleic anhydride is completely dissolved, add 2 g of organic peroxide initiator in 2 portions (1 g each time, 10 min apart), and continue the reaction at 190 °C for 60 min. Collect the melt after the reaction. At 190℃, the vacuum was switched to 10kPa absolute pressure and maintained for 20min. Then, nitrogen slight positive pressure was restored, the temperature was lowered to 170℃ and stirred at 200rpm. First, 80g of polyethylene glycol methyl etheramine was added dropwise over 15min and the reaction was kept at this temperature for 40min. Then, 50g of polyether monoamine was added over 20min and the reaction was kept at this temperature for 60min. Finally, 20g of octadecaneamine was added over 10min and the reaction was kept at this temperature for 40min. The temperature was then raised to 180℃ and the vacuum was switched to 10kPa absolute pressure and maintained for 30min. Nitrogen protection was then restored. While hot, the obtained functional tackifier melt was poured onto silicone paper, cooled into blocks, and then crushed and granulated to obtain functional tackifier particles for sealing hot melt adhesive. Step 2: Purge the jacketed heating and stirring mixing vessel with nitrogen at 200 mL / min for 15 min. Then, add 600 g of polyolefin elastomer, 200 g of Fischer-Tropsch wax, and 100 g of microcrystalline wax sequentially. Heat to 150°C and stir at 60 rpm for 30 min. At 150°C, add 200 g of ethylene-vinyl acetate copolymer particles in three portions (70 g, 70 g, and 60 g each time, with 10 min intervals). Then, heat to 160°C and continue stirring for 4 minutes. 0 min; then maintain 160℃ and add 400g of hydrogenated hydrocarbon tackifying resin, stir for 30 min and then cool the system to 150℃; then add 492g of functional tackifying phase particles in 4 batches (123g each time, 8 min apart), and continue stirring for 40 min; after cooling to 140℃, add 8g of antioxidant 1010 and stir for 10 min, then filter while hot at 140℃ through a 120-mesh stainless steel filter and pour into blocks to cool, to obtain low-temperature fast-sealing high initial tack hot melt adhesive for sealing boxes.

[0030] Example 2: Compared with Example 1, in step 1, the total amount of maleic anhydride added in 5 portions was 20g (4g each time, 4min interval, 200rpm). After the maleic anhydride was completely dissolved, the total amount of organic peroxide initiator added in 2 portions was 1.5g (0.75g each time, 10min interval), and the reaction was continued at 190℃ for 50min. The other conditions were the same as in Example 1.

[0031] Example 3: Compared with Example 1, in step 1, the total amount of maleic anhydride added in 5 portions was 30g (6g each time, 4min interval, 200rpm). After the maleic anhydride was completely dissolved, the total amount of organic peroxide initiator added in 2 portions was 2.5g (1.25g each time, 10min interval), and the reaction was continued at 190℃ for 70min. The other conditions were the same as in Example 1.

[0032] Example 4: Compared with Example 1, in step 1, after cooling to 170°C, 100g of polyethylene glycol methyl etheramine was added dropwise over 15 minutes and the reaction was maintained at this temperature for 40 minutes. Then, 40g of polyether monoamine was added over 20 minutes and the reaction was maintained at this temperature for 60 minutes. Finally, 15g of octadecylamine was added over 10 minutes and the reaction was maintained at this temperature for 40 minutes. The remaining conditions were the same as in Example 1.

[0033] Example 5: Compared with Example 1, in step 1, after cooling to 170°C, 60g of polyethylene glycol methyl etheramine was added dropwise over 15 minutes and the reaction was maintained at this temperature for 40 minutes. Then, 80g of polyether monoamine was added over 20 minutes and the reaction was maintained at this temperature for 60 minutes. Finally, 25g of octadecylamine was added over 10 minutes and the reaction was maintained at this temperature for 40 minutes. The remaining conditions were the same as in Example 1.

[0034] Example 6: Compared with Example 1, in step 2, the mixing vessel with jacket heating and stirring was purged with nitrogen at 200 mL / min for 15 min, then 650 g of polyolefin elastomer, 180 g of Fischer-Tropsch wax, and 90 g of microcrystalline wax were added sequentially. The temperature was raised to 150 °C and stirred at 60 rpm for 30 min. At 150 °C, 220 g of ethylene-vinyl acetate copolymer particles were added in three portions (80 g, 80 g, and 60 g each time, with 10 min intervals). The temperature was then raised to 160 °C and stirring continued for 40 min. In the next step, maintain the temperature at 160°C and add 300g of hydrogenated hydrocarbon tackifying resin. Stir for 30 minutes and then cool the system to 150°C. Add 552g of functional tackifying phase particles in four batches (138g each time, 8 minutes apart) and continue stirring for 40 minutes. Cool to 140°C, add 8g of antioxidant 1010 and stir for 10 minutes. Then, while still hot at 140°C, filter through a 120-mesh stainless steel filter and pour into blocks to cool, thus obtaining a low-temperature fast-sealing high initial tack hot melt adhesive for sealing boxes. The remaining conditions are the same as in Example 1.

[0035] Comparative Example 1: The difference from Example 1 is that polyethylene glycol methyl etheramine is not added in step 1; the other conditions are the same as in Example 1.

[0036] Comparative Example 2: The difference from Example 1 is that no polyether monoamine is added in step 1; the other conditions are the same as in Example 1.

[0037] Comparative Example 3: The difference from Example 1 is that octadecylamine is not added in step 1; the other conditions are the same as in Example 1.

[0038] Comparative Example 4: The difference from Example 1 is that in step 1, after cooling to 170°C, 20g of octadecylamine is added within 10 minutes and the reaction is maintained at this temperature for 40 minutes. Then, 80g of polyethylene glycol methyl etheramine is added dropwise within 15 minutes and the reaction is maintained at this temperature for 40 minutes. Finally, 50g of polyether monoamine is added within 20 minutes and the reaction is maintained at this temperature for 60 minutes. The remaining conditions are the same as in Example 1.

[0039] Comparative Example 5: The difference from Example 1 is that in step 1, after cooling to 170°C, 50g of polyether monoamine is added within 20 minutes and the reaction is maintained at this temperature for 60 minutes. Then, 80g of polyethylene glycol methyl etheramine is added dropwise within 15 minutes and the reaction is maintained at this temperature for 40 minutes. Finally, 20g of octadecylamine is added within 10 minutes and the reaction is maintained at this temperature for 40 minutes. The remaining conditions are the same as in Example 1.

[0040] Comparative Example 6: The difference from Example 1 is that in step 2, instead of adding 492g of functional tackifying phase particles four times, 492g of hydrogenated hydrocarbon tackifying resin was added four times (123g each time, with an 8min interval), and no functional tackifying phase particles were added; the other conditions were the same as in Example 1.

[0041] Performance testing: Sample preparation and numbering: All samples were placed at (23±2)℃ and (50±5)% relative humidity for 24 hours for conditioning, in accordance with GB / T 2918-2018; In the low temperature related test, the hot melt adhesive sample and the substrate to be bonded were placed together in a 10℃ constant temperature chamber for 4 hours before application and testing. The samples used for intrinsic characterization were prepared as follows: each sample was melted in a constant temperature oil bath at 140℃ and allowed to stand for 5 minutes to degas. Then, it was poured into a polytetrafluoroethylene board mold preheated to 140℃ and coated into a film using a 1.00mm thick limiting frame. After cooling to 23℃, the samples were cut off. The substrate used for bonding performance testing was the same batch of A-flute corrugated cardboard (5.0mm thick, 8.0% moisture content). In application extension testing or equivalent verification, the substrate could also be thermoplastic polyolefin waterproof membrane. Overlapped samples were prepared according to the conventional working conditions of membrane overlap bonding and peel / shear tests were performed to verify the low-temperature fast sealing and initial adhesion establishment capabilities. After cutting, samples were taken in the same direction. No surface treatment was performed before testing.

[0042] Fourier transform infrared spectroscopy: ATR-FTIR mode was used, and the wavenumber range was 4000 cm⁻¹. -1 Up to 650cm -1 4cm resolution -1 The number of scans was 32, and the background was scanned 32 times.

[0043] Thermogravimetric analysis (TGA): Thermogravimetric analysis was performed according to GB / T 33047.1-2016. 8.0 mg of each sample thin film was placed in an alumina crucible. Nitrogen gas flow rate was 60 mL / min. The heating program was 30℃ to 600℃, with a heating rate of 10℃ / min. The 5% weight loss temperature T was recorded. 5% (°C) and temperature of maximum weight loss rate T max (°C).

[0044] Open time (low temperature and normal temperature): The open time was measured according to HG / T 3716-2003, and the sealing conditions were fixed. Hot melt adhesive was applied after being kept at 140℃ for 5 minutes. A 25mm × 25mm square adhesive layer was formed on the surface of A-flute corrugated cardboard at 10℃ (cardboard pre-cooled for 4 hours). The amount of adhesive applied at one time was 0.20g, and the thickness of the adhesive layer was controlled using a 0.30mm limiting scraper. After application, waiting times t were set sequentially in 0.5s increments (0.5s, 1.0s, 1.5s…10.0s). At t, a pressure of 0.30MPa was applied for 1.0s. After pressing, the surface was left to stand for 10s, and then the damage morphology was judged by manual peeling. Effective bonding was considered when the fiber tear area accounted for ≥80%. Open time OT 10 To meet the maximum t required for effective bonding, the ambient temperature was adjusted to 23℃, and OT was measured using the same method. 23 .

[0045] Initial and final 180° peel strength: Peel test specimens were prepared according to GB / T 2790-1995, with a quantitative strength of 80 g / m². 2 Kraft paper strips, 25mm wide and 200mm long, are used as the flexible material; A-flute corrugated cardboard is used as the rigid material, with a bonding length of 100mm. Hot melt adhesive is melted at 140℃ and applied to the cardboard to form a uniform adhesive layer 25mm wide, with a single application amount of 0.40g, and then pressed under a pressure of 0.20MPa for 2.0s. Initial peel strength P... 60s The sample was left to stand at 10℃ for 60 seconds before being peeled 180°. The clamping distance of the tensile testing machine was 100 mm, and the testing speed was 300 mm / min. The average peel force in the stable section was recorded and converted to N / 25 mm. The final peel strength P 24h The sample was left to stand at 23℃ for 24 hours before being tested in the same manner.

[0046] Tensile shear strength (initial and final states): Overlap shear specimens were prepared according to GB / T 7124-2008. The cardboard specimen size was 100mm × 25mm, and the overlap area was 25mm × 12.5mm. Adhesive was applied at 140℃, with a single application amount of 0.15g, and pressed at 0.30MPa for 5.0s. Initial shear strength τ 300s The specimen was subjected to tensile shear after being left to stand at 10℃ for 300 s. The test speed was 10 mm / min. The maximum load was recorded and converted to MPa based on the overlap area. The final shear strength τ 24h The sample was left to stand at 23℃ for 24 hours and then tested using the same method.

[0047] Low-temperature flexibility (mandrel bending method): The low-temperature flexibility was determined by mandrel bending method according to HG / T 4222-2011. Each sample was melted and cast into a test strip with a thickness of 1.00 mm, a width of 10 mm, and a length of 100 mm. The strip was placed at (23±2)℃ for 24 h and then placed in a constant temperature chamber at -10℃ for 4 h. After removal, the strip was bent 180° around a mandrel with a diameter of 10 mm within 2 s and held for 5 s. The maximum crack length L was then observed and measured under a 10× magnifying glass. crack (mm), with 0mm marked as no cracks.

[0048] Table 1 Performance Test Results

[0049] Data Analysis: As can be seen from the data in Table 1, the low-temperature fast-sealing high initial tack hot melt adhesive for boxes prepared by this invention maintains a high level of thermal stability, while the low-temperature open time, low-temperature initial peel strength, and lap shear strength show a synchronous increasing trend. Furthermore, the low-temperature flexibility does not exhibit significant deterioration that contradicts the adhesive strength. This may be because controlled maleic anhydride grafting of hydrogenated hydrocarbon tackifying resin is achieved through an organic peroxide initiator, followed by the sequential introduction of polyethylene glycol methyl etheramine, polyether monoamine, and octadecylamine, resulting in functional tackifying phase particles with both polar action sites and hydrophobic segments. PEG methyl etheramine promotes rapid spreading of the adhesive on the corrugated cardboard surface, the long-chain segments of polyether monoamine enhance cohesive entanglement and buffer low-temperature stress, while the octadecylamine end groups improve its compatibility with polyolefin elastomers, ethylene-vinyl acetate copolymers, and wax phases. This allows for the formation of a continuous adhesive film and inhibits brittleness even at cold temperatures, demonstrating the coupling gain of interfacial wetting and cohesive enhancement.

[0050] As can be seen from the data in Example 1 and Comparative Example 1 in Table 1, when polyethylene glycol methyl etheramine is not introduced during the preparation of the functional tackifying phase particles, the low-temperature open window narrows, and both the initial low-temperature peel strength and the short-time lap shear strength show a decreasing trend. The main reason for this is likely the reduction in polar interaction sites, which limits the wetting and penetration of the hydrogenated hydrocarbon tackifying resin into the paper fibers, making it difficult for the colloid to establish an effective interface in a short pressing time at low temperatures. Although polyether monoamine and octadecylamine can still provide a certain degree of cohesion and flexibility, the lack of rapid spreading contribution from polyethylene glycol methyl etheramine makes it difficult to simultaneously achieve low-temperature fast sealing performance, indicating that multi-segment synergy is not a simple superposition.

[0051] As can be seen from the data in Table 1 for Example 1 and Comparative Example 2, when only polyethylene glycol methyl etheramine and octadecylamine are retained while polyether monoamine is lacking, the initial low-temperature peel strength can still be maintained at a high level, but the low-temperature flexibility is significantly worse, and the improvement in lap shear strength is limited. The presumed reason is that although polyethylene glycol methyl etheramine is beneficial for cold wetting and rapid interface establishment, the lack of polyether monoamine with a larger molecular weight results in insufficient chain entanglement and stress dissipation capacity within the film. After the wax phase cools, it is more prone to brittle cracking and stress transfer to the interface, making it difficult to simultaneously achieve high initial tack and crack resistance.

[0052] As can be seen from the data in Table 1 for Example 1 and Comparative Example 3, when the functional tackifying phase particles were not end-capped with octadecaneamine, both thermal stability and low-temperature flexibility decreased, while the stability of low-temperature open time and initial strength weakened. The main reason for this is likely that the residual maleic anhydride structure and its hydrolysis products result in a higher polarity of the system, leading to poor compatibility with polyolefin elastomers, ethylene-vinyl acetate copolymers, and the wax phase. This results in the formation of discontinuous films and induces crack propagation during low-temperature bending. Therefore, octadecaneamine is not only used to adjust polarity but also provides comprehensive benefits by improving compatibility and interfacial continuity.

[0053] As can be seen from the data in Table 1 for Example 1 and Comparative Examples 4 and 5, even if the types and amounts of raw materials remain the same, changing only the order of addition of octadecaneamine, polyethylene glycol methyl etheramine, and polyether monoamine will lead to varying degrees of deterioration in low-temperature open time and low-temperature initial strength, and flexibility is difficult to improve simultaneously. It is speculated that adding octadecaneamine or polyether monoamine first will preferentially occupy maleic anhydride grafting sites, resulting in uneven distribution of subsequent chain segments and an imbalance between the polarity and hydrophobic structure of the functional tackifying phase particles, thereby weakening the rapid wetting of paper fibers and the buffering effect against wax phase embrittlement.

[0054] As can be seen from the data in Table 1 for Example 1 and Comparative Example 6, when the system uses only hydrogenated hydrocarbon tackifying resin without introducing functional tackifying phase particles, the low-temperature open time is significantly shortened, and the low-temperature initial peel strength and short-term lap shear strength are both at a low level, accompanied by more obvious low-temperature cracking. This is because traditional tackifying resins are mainly hydrophobic phases, resulting in insufficient spreading and penetration to the corrugated cardboard surface in the cold state. Furthermore, the rapid crystallization of the wax phase further exacerbates interfacial discontinuity, leading to slow initial tack establishment and poor impact resistance. In contrast, Example 1, through controlled grafting and polyamine synergistic regulation, couples wetting, cohesion, and flexibility into the same functional phase, achieving simultaneous improvement in both low-temperature fast sealing and high initial tack, demonstrating a synergistic mechanism where one plus one equals more than two.

[0055] from Figure 1 It can be seen that the low-temperature fast-sealing high initial adhesion hot melt adhesive in this embodiment is effective at 2920cm. -1 and 2850cm -1 The strong -CH2- stretching vibration absorption at 1735 cm⁻¹ indicates a high proportion of long-chain hydrocarbon segments such as polyolefin elastomers, EVA, and waxes in the system; -1 Strong ester C=O stretching peaks appear on both sides, and are located between 1705-1545 cm⁻¹. -1 The presence of amide / imide-related C=O, amide I, and amide II absorptions at 1600 cm⁻¹ indicates that the maleic anhydride-grafted hydrogenated hydrocarbon resin has fully reacted with polyethylene glycol methyl ether amine and polyether monoamine to form a functional tackifying phase; -1 Nearby weak peaks and 1250cm -1 The absorption in this zone is attributed to the antioxidant aromatic ring and the CO vibration of esters / aryl ethers. 1160cm -1 and 1100cm -1 The strong COC stretching peak indicates that PEG and polyether segments were successfully introduced, which is beneficial for enhancing the polar wetting of paper fibers; while the 1465 cm⁻¹ peak indicates that PEG and polyether segments were successfully introduced. -1 1377cm -1 and 720cm -1 The bending and rocking vibrations of CH2 at the point further confirm the existence of the long-chain alkane crystalline phase.

[0056] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A low-temperature, fast-sealing, high-initial-adhesion hot melt adhesive for sealing boxes, characterized in that, The product comprises, by weight parts: 600-650 parts polyolefin elastomer; 180-200 parts Fischer-Tropsch wax; 90-100 parts microcrystalline wax; 200-220 parts ethylene-vinyl acetate copolymer; 300-400 parts hydrogenated hydrocarbon tackifying resin; and 492-552 parts functional tackifying phase particles; wherein the functional tackifying phase particles are obtained by grafting maleic anhydride onto the hydrogenated hydrocarbon tackifying resin, followed by sequential reaction with polyethylene glycol methyl ether amine, polyether monoamine, and octadecylamine; The functional tackifying phase particles are prepared from the following raw materials in parts by mass: 1000 parts hydrogenated hydrocarbon tackifying resin, 20-30 parts maleic anhydride, 1.5-2.5 parts organic peroxide initiator, 60-100 parts polyethylene glycol methyl ether amine, 40-80 parts polyether monoamine and 15-25 parts octadecylamine.

2. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, It also includes 8 portions of antioxidant 1010.

3. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, The organic peroxide initiator is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

4. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, The polyolefin elastomer has an ethylene content of 11wt%-13wt%, a melting point of 90-110℃, and a glass transition temperature of -31±2℃.

5. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, The hydrogenated hydrocarbon tackifying resin is a fully hydrogenated hydrocarbon resin with a ring and ball softening point of 90-110℃.

6. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, The vinyl acetate content of the ethylene-vinyl acetate copolymer is 27wt%-29wt%, and the melt index at 190℃ / 2.16kg is 380-420g / 10min.

7. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, The polyethylene glycol methyl ether amine is from the Sigma-Aldrich brand, product number 767565; the polyether monoamine is from Huntsman, model JEFFAMINE M-2005.

8. The low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 1, characterized in that, The preparation steps of the functional thickening phase particles are as follows: (1) After heating and melting the hydrogenated hydrocarbon tackifying resin under nitrogen protection, maleic anhydride is added and grafting reaction is carried out under the action of organic peroxide initiator to obtain maleic anhydride grafted modified hydrogenated hydrocarbon tackifying resin melt. (2) After the melt obtained in step (1) is devastated and cooled, polyethylene glycol methyl etheramine, polyether monoamine and octadecylamine are added in sequence to react and obtain a functional thickening phase melt; (3) After the functional thickening phase melt obtained in step (2) is devolatilized, cooled and pulverized into granules to obtain functional thickening phase particles.

9. A method for preparing a low-temperature fast-sealing, high-initial-adhesion hot melt adhesive for boxes according to any one of claims 1-8, characterized in that, The process includes the following steps: melting and mixing polyolefin elastomer, Fischer-Tropsch wax and microcrystalline wax, then adding ethylene-vinyl acetate copolymer and mixing, then adding hydrogenated hydrocarbon tackifying resin and mixing, followed by adding the functional tackifying phase particles and mixing to obtain a molten colloid, which is then cooled and molded to obtain a low-temperature fast-sealing high initial tack hot melt adhesive for sealing boxes.

10. The method for preparing the low-temperature fast-sealing, high initial adhesion hot melt adhesive for sealing boxes according to claim 9, characterized in that, Polyolefin elastomer, Fischer-Tropsch wax, and microcrystalline wax were heated to 150°C and stirred at 60 rpm for 30 min. Ethylene-vinyl acetate copolymer was added in three portions at 150°C with 10 min intervals between each addition. The mixture was then heated to 160°C and stirred for another 40 min. Hydrogenated hydrocarbon tackifying resin was added and stirred for 30 min. The system was then cooled to 150°C. Functional tackifying phase particles were added in four portions at 150°C with 8 min intervals between each addition. The mixture was stirred for another 40 min. The mixture was then cooled to 140°C and antioxidant 1010 was added and stirred for 10 min. Finally, the mixture was filtered through a 120-mesh stainless steel filter while still hot and then cast and cooled to form the final product.

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