Environment-friendly wide-temperature-range adhesive tape with high-toughness structure and preparation method of environment-friendly wide-temperature-range adhesive tape

Abstract

The invention discloses an environment-friendly wide-temperature-range adhesive tape with a high-toughness structure and a preparation method of the environment-friendly wide-temperature-range adhesive tape, and belongs to the technical field of high-performance composite materials. The core-shell particles with the soft core-hard shell structure are added, the core layer is composed of the elastic polymer with the glass transition temperature lower than-20 DEG C, the shell layer is the rigid polymer with the glass transition temperature higher than 60 DEG C, and the wide temperature range self-adaption of the high-toughness structure adhesive tape to summer and winter environments is achieved through the synergistic effect of temperature-sensitive characteristics. In a summer high-temperature environment, the rigid shell layer plays a microscopic scaffold effect and a physical cross-linking strengthening effect and inhibits flowing permeation of a sizing material to micropores of the release paper. And in a low-temperature scene in winter, the elastomer of the core layer still maintains high elasticity, can absorb and dissipate impact energy, serves as a microscopic pressure head, enhances mechanical interlocking and Van der Waals' force effects, and rapidly establishes sufficient initial adhesive force. And the contradictory problems of constructability and reliability of difficult paper uncovering in summer and poor adhesion in winter of the structural adhesive tape are integrally solved.

Description

Technical Field

[0001] This invention relates to the field of high-performance composite materials technology, and in particular to an environmentally friendly, wide-temperature-range bonding, high-toughness structural tape and its preparation method. Background Technology

[0002] High-toughness structural tapes, as lightweight and high-strength adhesive and sealing materials, are widely used in the automotive, electronics, and aerospace industries. Through foaming and expansion during curing, they can fill irregular gaps, achieving weight reduction and sound insulation while maintaining excellent structural strength. However, in practical applications, especially in environments experiencing drastic seasonal temperature differences, these tapes face a long-standing and unresolved core contradiction: their ease of application at high summer temperatures and reliable adhesion at low winter temperatures cannot be simultaneously achieved, severely limiting their reliable application across a wide temperature range.

[0003] Specifically, existing technologies face the following two interrelated challenges: The problem of "difficulty in peeling back release paper" in summer: When the ambient temperature rises (usually exceeding 35℃), the adhesive layer softens due to increased polymer chain movement, leading to a decrease in cohesive strength and a significant increase in fluidity. This makes it extremely easy for the adhesive to excessively penetrate into the microporous structure of the release paper during storage or pre-lamination, forming a strong physical "anchoring" effect. The consequence is a sharp increase in the peeling force required when removing the release paper during construction, resulting in difficulty in peeling, adhesive layer stringing, and even deformation, severely affecting construction efficiency and appearance.

[0004] The problem of poor adhesion in low winter temperatures: When the ambient temperature drops (usually below 5°C), the movement of polymer chains in the adhesive freezes, and the material transforms from a highly elastic state to a glassy state. Macroscopically, this manifests as a sharp increase in the modulus of the tape matrix, making it harder and more brittle. This directly leads to two negative effects: First, the initial tack (wetting ability) of the tape decreases, making it unable to flow under slight pressure and wet the microscopic irregularities on the surface of the adhered object (such as a steel plate), resulting in failure to establish initial adhesion and the tape failing to "stick." Second, the toughness of the material decreases sharply, making it prone to brittle fracture when subjected to bending or impact, thus compromising reliability.

[0005] To address the problem of a single temperature point, existing technologies typically employ a discrete and mutually restrictive strategy: To address the difficulty of removing release paper in summer, a common practice is to add rigid inorganic or organic microparticles (such as silica or PMMA microspheres) to the adhesive, intending to reduce the contact area between the adhesive layer and the release paper through their physical support. However, these rigid particles become stress concentration points at low temperatures, exacerbating the brittleness of the matrix and deteriorating low-temperature performance.

[0006] To address poor adhesion in winter, the mainstream solution is to introduce plasticizers or flexible polymers (such as CTBN rubber and polyurethane) for toughening. However, this often leads to a further decrease in the modulus and increased fluidity of the adhesive at high temperatures, which in turn exacerbates the problems of difficulty in peeling off paper and insufficient cohesive strength in summer.

[0007] At its core, the predicament of existing technologies stems from the one-way adjustment of material properties' temperature dependence. Whether enhancing high-temperature rigidity or improving low-temperature flexibility, traditional methods have failed to surpass the optimization of performance at a single temperature point; their effects are often inversely related, unable to construct a self-regulating "contradictory unity" over a wide temperature range. Therefore, developing a novel high-toughness structural tape that can adapt to changes in ambient temperature and comprehensively resolve the contradiction between high and low temperature performance has become a critical technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0008] To address the aforementioned technical problems in the prior art, this invention aims to provide an environmentally friendly, wide-temperature-range bonding, high-toughness structural tape and its preparation method.

[0009] One objective of this invention is to provide an environmentally friendly, wide-temperature-range bonding, high-toughness structural tape, wherein the high-toughness structural tape comprises the following raw materials in parts by weight: Solid epoxy resin 20-30 parts, liquid epoxy resin 15-20 parts, toughened modified epoxy resin 30-40 parts, core-shell particles 20-25 parts, curing agent 4-6 parts, curing accelerator 0.4-0.6 parts, foaming agent 2-3 parts, foaming accelerator 0.4-0.8 parts, carbon black 4-6 parts, fiber 1-2 parts, filler 3-6 parts, desiccant 1-2 parts, silane coupling agent 0.1-0.2 parts; The core-shell particles are polymer microparticles with a core-shell structure, wherein the core layer is an elastic polymer with a glass transition temperature below -20°C, and the shell layer is a rigid polymer with a glass transition temperature above 60°C; the volume-weighted median particle size D50 of the core-shell particles is 10~15μm, and their specific surface area is greater than 1.5m². 2 / g.

[0010] Preferably, the particle size distribution span (D90 - D10) / D50 of the core-shell particles is 1.5~2.

[0011] Preferably, the core polymer of the core-shell particles includes one or more of polybutyl acrylate, polybutadiene rubber, silicone rubber, and polyurethane elastomer; the shell polymer of the core-shell particles includes one or more of polymethyl methacrylate, polystyrene, polyethyl methacrylate, and styrene-acrylonitrile copolymer.

[0012] Preferably, the core polymer of the core-shell particles is polybutyl acrylate, and the shell polymer is polymethyl methacrylate.

[0013] Preferably, the method for preparing the core-shell particles includes: S1. Preparation of core emulsion: By weight, add 80 parts butyl acrylate, 2 parts propylene glycol diester methacrylate, 1.5 parts sodium dodecyl sulfate and 150-200 parts water, and heat to 75-85°C under inert gas protection, and stir at 500 r / min for 30 min to form a uniform emulsion. While maintaining the temperature and stirring, add an initiator solution to the above homogeneous emulsion. The initiator solution is prepared by dissolving 0.3 parts of ammonium persulfate in 10-20 parts of water. Carry out the emulsion polymerization reaction at 75-85°C for 2-4 hours to obtain a polybutyl acrylate seed emulsion. S2. Shell coating polymerization In the polybutyl acrylate seed emulsion, under conditions of maintaining a temperature of 75°C to 85°C and stirring, the solution was added dropwise at a uniform rate through two constant-pressure dropping funnels. Solution A: Mix 20 parts methyl methacrylate, 0.5 parts propylene glycol diester methacrylate, 1 part glycidyl methacrylate, 0.2 parts sodium dodecyl sulfate, and 20-40 parts water, and stir at 500 r / min for 30 min to form a pre-emulsified monomer solution. Solution B: An initiator solution obtained by dissolving 0.3 parts potassium persulfate in 10-20 parts deionized water; Solution A and solution B are added simultaneously over 3 to 4 hours. After the addition is complete, the reaction is continued at 80°C for 1 to 2 hours to obtain the core-shell emulsion. S3. Post-processing: The core-shell emulsion obtained in step S2 is subjected to coagulation, filtration, washing, drying and deagglomeration to obtain core-shell particle powder.

[0014] Preferably, the core-shell particles are modified with a silane coupling agent, and the amount of the silane coupling agent is 1 to 5% of the mass of the core-shell particle powder.

[0015] Preferably, the toughening modified epoxy resin includes one or more of polyurethane modified epoxy resin, CTBN modified epoxy resin, and core-shell polymer predispersed epoxy resin.

[0016] Preferably, the curing agent includes one or more of dicyandiamide, sebacate dihydrazide, or adipic acid dihydrazide.

[0017] Preferably, the curing accelerator includes an organic urea accelerator.

[0018] Preferably, the foaming agent includes azodicarbonamide.

[0019] Preferably, the foaming accelerator includes urea and zinc oxide.

[0020] Preferably, the solid epoxy resin includes one or more of CYD-012, CYD-011, and CYD-014U.

[0021] Preferably, the liquid epoxy resin includes bisphenol A type epoxy resin and / or semi-solid epoxy resin, with bisphenol A type epoxy resin being the most preferred.

[0022] Preferably, the carbon black includes acetylene black and / or conductive carbon black.

[0023] Preferably, the fiber is one or more of polyester fiber, aramid fiber and glass fiber.

[0024] Preferably, the inorganic filler comprises nano-calcium carbonate and / or talc.

[0025] Preferably, the desiccant comprises calcium oxide.

[0026] Preferably, the silane coupling agent includes KH560 and / or KH580.

[0027] The second objective of this invention is to provide a method for preparing the high-toughness structural adhesive tape as described above, characterized by comprising the following steps: Heat the kneader to 70℃~80℃, add the solid epoxy resin, and after it is completely melted, add the carbon black, filler, desiccant, core-shell particles and fiber for mixing. After the mixture is uniform, add the liquid epoxy resin. Then, the toughening modified epoxy resin and silane coupling agent are added in sequence, and the mixture is stirred for 20-30 minutes after each addition; Finally, the curing agent, curing accelerator, foaming agent, and foaming accelerator are added, and the mixture is stirred evenly to obtain the adhesive material. The resulting material is then molded to obtain the structural tape.

[0028] The beneficial effects of this invention include: The core-shell particles of this invention are designed with a soft core-hard shell structure as the core: the core layer is made of an elastic polymer with a glass transition temperature below -20°C, while the shell layer is made of a rigid polymer with a glass transition temperature above 60°C. Through the synergistic effect of temperature-sensitive properties, the high-toughness structural tape achieves wide temperature range adaptability to summer and winter environments.

[0029] In high-temperature summer scenarios, the shell layer remains rigid, which on the one hand plays a micro-scaffolding effect: the uniformly dispersed core-shell particles form physical support points between the adhesive layer and the release paper, greatly reducing the effective contact area between the two and reducing the peel force to achieve easy paper removal; on the other hand, it is strengthened by physical cross-linking, acting as a rigid dispersed phase to serve as a physical cross-linking point of the adhesive matrix, constraining the movement of polymer chain segments, improving the high-temperature modulus and cohesive strength of the system, while increasing viscosity and introducing yield stress, inhibiting the flow and penetration of the adhesive into the micropores of the release paper.

[0030] In low-temperature winter scenarios, the elastomer in the core layer maintains high elasticity: it acts as a stress concentration point, inducing the matrix to produce crazes and shear bands, absorbing and dissipating impact energy, and significantly improving the tape's low-temperature toughness and resistance to brittle fracture; at the same time, the core-shell particles act as micro-indenters, applying localized high pressure to the hardened adhesive during external force pressing, promoting its filling of the micro-unevennesses on the surface of the adhered objects, enhancing mechanical interlocking and van der Waals forces, and quickly establishing sufficient initial adhesion.

[0031] In summary, the soft-core-hard-shell structure of core-shell particles, relying on its temperature-sensitive properties, comprehensively solves the contradiction between workability and reliability of high-toughness structural tapes in wide temperature range environments, such as difficulty in peeling off paper in summer and poor adhesion in winter. Attached Figure Description

[0032] Figure 1 This is a particle size distribution diagram of the core-shell particles described in Example 1; Figure 2 The infrared spectrum of the core-shell particles described in Example 1; Figure 3 The thermogravimetric analysis diagram of the core-shell particles described in Example 1 is shown. Detailed Implementation

[0033] The following description includes certain specific details to provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented without employing one or more of these specific details, but using other methods, components, materials, etc.

[0034] Unless otherwise required by the present invention, throughout the specification and the following claims, the words “comprising” and “including” shall be interpreted in an open-ended, inclusive sense, meaning “including but not limited to”.

[0035] Throughout this specification, the terms "an embodiment," "an embodiment," "a preferred embodiment," or "some embodiments" refer to including, in at least one embodiment, a specific reference element, structure, or feature associated with that embodiment. Therefore, the phrases "in an embodiment," "in a preferred embodiment," or "in some embodiments" appearing in different places throughout the specification do not necessarily all refer to the same embodiment. Furthermore, specific elements, structures, or features may be combined in one or more embodiments in any suitable manner.

[0036] According to a first aspect of the present invention, an environmentally friendly, wide-temperature-range bonding, high-toughness structural tape is provided, the high-toughness structural tape comprising the following raw materials in parts by weight: Solid epoxy resin 20-30 parts, liquid epoxy resin 15-20 parts, toughened modified epoxy resin 30-40 parts, core-shell particles 20-25 parts, curing agent 4-6 parts, curing accelerator 0.4-0.6 parts, foaming agent 2-3 parts, foaming accelerator 0.4-0.8 parts, carbon black 4-6 parts, fiber 1-2 parts, filler 3-6 parts, desiccant 1-2 parts, silane coupling agent 0.1-0.2 parts; The core-shell particles are polymer microparticles with a core-shell structure, wherein the core layer is an elastic polymer with a glass transition temperature below -20°C, and the shell layer is a rigid polymer with a glass transition temperature above 60°C; the volume-weighted median particle size D50 of the core-shell particles is 10~15 μm, and their specific surface area is greater than 1.5 m². 2 / g.

[0037] In this invention, the core-shell particles have a "soft core-hard shell" structure, with the core layer composed of an elastic polymer with a glass transition temperature (Tg) below -20°C, and the shell layer composed of a rigid polymer with a glass transition temperature (Tg) above 60°C. This structural design enables it to achieve wide-temperature-range adaptive performance by addressing the contradictory problems of difficult paper removal at high summer temperatures and poor adhesion at low winter temperatures through the following synergistic mechanisms: 1. Mechanism of action under high summer temperatures Microscopic scaffolding effect: Under high summer temperatures (e.g., 40°C), the shell layer remains rigid, and the core-shell particles uniformly dispersed in the adhesive layer form physical support points between the adhesive layer and the release paper, significantly reducing the effective contact area between the two, thereby greatly reducing the peeling force and achieving easy paper removal.

[0038] Physical crosslinking reinforcement: The shell layer, as a rigid dispersed phase, acts as a physical crosslinking point in the adhesive matrix, constraining the movement of polymer chain segments, improving the modulus and cohesive strength of the system at high temperatures, while increasing the viscosity of the system and introducing yield stress, effectively inhibiting the flow and penetration of the adhesive into the micropores of the release paper.

[0039] 2. Mechanism of action under low temperatures in winter Macroscopic toughening mechanism: The elastomer in the core layer maintains high elasticity under low temperature conditions (such as below 0°C), which acts as a stress concentration point and induces the matrix to generate crazes and shear bands, absorbing and dissipating impact energy, thereby significantly improving the low temperature toughness and resistance to brittle fracture of the tape.

[0040] Microscopic adhesion enhancement mechanism: During the external force pressing process, the rigid shell of the core-shell particles acts as a "microscopic pressure head," generating local high pressure on the hardened adhesive around it, prompting it to better fill the microscopic unevenness of the surface of the adhered object, enhancing mechanical interlocking and van der Waals forces, thereby rapidly establishing sufficient initial adhesion force at low temperatures.

[0041] In summary, the core-shell particles, through their unique "soft core-hard shell" structure and temperature-sensitive properties, can play a supporting and reinforcing role at high temperatures by relying on the rigid shell, and achieve toughening and adhesion promotion by relying on the elastic core at low temperatures. This integrated solution addresses the contradiction between the workability and reliability of high-toughness structural tapes in a wide temperature range environment.

[0042] In this invention, when the amount of core-shell particles is less than 20 parts, the microscopic scaffolding effect of the core-shell particles is insufficient, the adhesive still easily penetrates the release paper, the paper peeling resistance is relatively high, and it is difficult to effectively induce silver streaks and shear bands in the matrix at low winter temperatures, and it is also difficult to quickly establish sufficient initial adhesion. When the amount of core-shell particles is greater than 25 parts, the excessive core-shell particles are prone to agglomeration in the adhesive, which destroys the continuity of the epoxy resin matrix and leads to a significant decrease in shear strength; at the same time, agglomerated particles will become stress concentration points, which may exacerbate the risk of brittle fracture of the adhesive layer at low winter temperatures; in addition, excessive particles will cause the foaming ratio to be too high, the cells are prone to merge and become too large, losing the support strength required for the structural tape, and the viscosity of the adhesive is too high, resulting in poor adhesion and wetting during construction. The core-shell particles are, for example, 20 parts, 20.5 parts, 21 parts, 21.5 parts, 22 parts, 22.5 parts, 23 parts, 23.5 parts, 24 parts, 24.5 parts, or 25 parts.

[0043] In this invention, the volume-weighted median particle size D50 of the core-shell particles is 10-15 μm. This is because particles that are too small are easily submerged by the softened adhesive layer and cannot effectively support the release paper; particles in the 10-15 μm size range can reliably form point contacts, significantly reducing the actual contact area. Their specific surface area is greater than 1.5 m². 2The high surface energy of the core-shell particles ( / g) indicates the presence of numerous submicron-sized fine particles. These numerous fine particles provide a large number of stress concentration points, maximizing the induction of crazes and shear bands, thus maximizing the absorption of impact energy—crucial for addressing winter brittleness. Simultaneously, the large surface area facilitates surface modification and interfacial bonding with the matrix. Furthermore, it aids in micro-adhesion, ensuring that the tape not only resists impact and cracking at low temperatures but also promotes adhesive flow through particle compression, rapidly establishing initial tack.

[0044] In this invention, the epoxy equivalent of the solid epoxy resin is 450~3000 g / eq, and the epoxy equivalent of the liquid epoxy resin is 180~250 g / eq. The solid epoxy resin is used to construct the mechanical framework and stability of the adhesive, while the liquid epoxy resin is used to reduce the overall viscosity and improve the initial wettability and adhesion of the adhesive. Their synergistic effect also facilitates the uniform dispersion of core-shell particles, fibers, etc., in the adhesive and promotes the formation of a uniform and stable closed-cell foam structure. The solid and liquid epoxy resins promote the formation of an epoxy resin matrix that is easy to mold during processing, conducive to foaming during curing, possesses both high strength and good toughness in the final state, and exhibits excellent synergy with the core-shell particles. The solid epoxy resin is, for example, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, or 30 parts. The liquid epoxy resin is, for example, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, or 20 parts.

[0045] The solid epoxy resin includes one or more of CYD-012, CYD-011, and CYD-014U.

[0046] The liquid epoxy resin includes one or more types of bisphenol A type epoxy resin and semi-solid epoxy resin, with bisphenol A type epoxy resin being preferred.

[0047] The toughening modified epoxy resin is used to pre-enhance the toughness of the matrix and can synergistically form a composite toughening system of continuous phase + dispersed phase with core-shell particles, which is beneficial for synergistically improving the low-temperature brittleness of the adhesive. The toughening epoxy resin is, for example, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, or 40 parts.

[0048] The curing agent and curing accelerator form a curing system used to crosslink and cure the epoxy resin. The curing agent is, for example, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, or 6 parts. The curing accelerator is, for example, 0.4 parts, 0.42 parts, 0.44 parts, 0.46 parts, 0.48 parts, 0.5 parts, 0.52 parts, 0.54 parts, 0.56 parts, 0.58 parts, or 0.6 parts.

[0049] The foaming agent and foaming accelerator, as a foaming system, are used to generate gas through thermal decomposition, forming a closed-cell foam structure within the rubber compound, thereby achieving lightweighting and gap filling. The core-shell particles also stabilize the cells, preventing cell merging or collapse at high temperatures. The foaming agent is, for example, 2 parts, 2.1 parts, 2.5 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, or 3 parts. The foaming accelerator is, for example, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts, or 0.8 parts.

[0050] The carbon black includes acetylene black and / or conductive carbon black. The carbon black is, for example, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, or 6 parts.

[0051] The filler is an inorganic filler, including nano-calcium carbonate and / or talc powder, which mainly serves as a reinforcement. The filler is, for example, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, or 6 parts.

[0052] The fiber includes one or more of polyester fiber, aramid fiber and glass fiber, and the fiber is a short-cut fiber with a length of 0.2 mm to 1.0 mm and a diameter of 5 μm to 20 μm. The fiber is, for example, 1 part, 1.1 parts, 1.2 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts or 2 parts.

[0053] The fibers can form a three-dimensional support network during the foaming process of the adhesive, working synergistically with the core-shell particles and fillers. On the one hand, this stabilizes the cell structure and ensures morphological stability at high foaming ratios; on the other hand, it further enhances the mechanical properties of the tape on a macroscopic scale, especially bridging cracks at low temperatures. It can form a multi-level synergistic reinforcement network with the core-shell particles, jointly ensuring the reliability of the tape over a wide temperature range.

[0054] The desiccant is used to absorb moisture to ensure the storage stability of the rubber compound. The desiccant includes calcium oxide. The amount of the desiccant is, for example, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, or 2 parts.

[0055] The silane coupling agent includes KH560 and / or KH580, used to improve the inorganic / organic interface bonding, strengthen the chemical bond between core-shell particles, fillers, fibers and epoxy resin matrix, and ensure effective stress transfer to the elastic core of the core-shell particles. The amount of the silane coupling agent used is, for example, 0.1 parts, 0.11 parts, 0.12 parts, 0.13 parts, 0.14 parts, 0.15 parts, 0.16 parts, 0.17 parts, 0.18 parts, 0.19 parts or 0.2 parts.

[0056] Preferably, the mass ratio of the solid epoxy resin to the liquid epoxy resin is 1.2 to 1.6:1, for example, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, 1.5:1, 1.55:1, or 1.6:1. When the ratio is less than 1.2:1, there is a relatively higher amount of liquid resin, resulting in a system viscosity that is too low. Although processing is very easy, the modulus and strength of the cured tape may be insufficient, making it prone to deformation at high temperatures. Furthermore, bubbles tend to merge and escape during the foaming process, which is not conducive to forming stable and uniform cells. When the ratio is greater than 1.6:1, there is a relatively higher amount of solid resin, resulting in a system viscosity that is too high at processing temperatures. This leads to difficulties in dispersing fillers such as fibers and core-shell particles, increasing energy consumption, and worsening the initial tack and wettability of the tape to the adhered object.

[0057] The matrix modulus of this ratio (1.2~1.6:1) is moderate, which can form a good modulus match with the rigid shell of the core-shell particles, facilitating the effective transfer of stress from the matrix to the core-shell particles. At the same time, sufficient liquid resin ensures that the tape still has the necessary flexibility and initial tack at low temperatures, working together with the elastic core of the core-shell particles to synergistically solve the problem of poor adhesion at low temperatures in winter.

[0058] A resin ratio between 1.2 and 1.6:1 ensures that the compound forms a paste-like, highly pliable, and uniform processing state at a kneading temperature of 70-80°C, providing the physical basis for the uniform dispersion of all components. Within this ratio range, the resin mixture maintains a viscosity sufficient to encapsulate gas and form closed cells near the decomposition temperature of the foaming agent (approximately 180°C), without being excessively high and inhibiting cell expansion, thus stably achieving a high foaming ratio. After curing, the long-chain solid resin provides a rigid framework, while the short-chain liquid resin fills the network gaps and toughens the structure. Together, they construct a high-strength, high-modulus matrix with a certain degree of toughness, providing a good foundation for the efficient toughening of core-shell particles.

[0059] In a preferred embodiment of the present invention, the particle size distribution span (D90 - D10) / D50 of the core-shell particles is 1.5~2.

[0060] In this invention, by controlling the particle size distribution range of the core-shell particles between 1.5 and 2, it is beneficial to ensure that the core-shell particle group can provide sufficiently rigid micron-sized particles to form a stable microscopic scaffold, effectively reducing high-temperature paper release force; at the same time, it can provide a large number of submicron-sized particles with high specific surface area to achieve extremely high toughening efficiency, ensuring low-temperature bonding reliability. Simultaneously, this range avoids the defects caused by uneven performance or excessively large particles that may result from an overly wide distribution, thus contributing to a balance between the overall performance and process stability of the tape.

[0061] In a preferred embodiment of the present invention, the core layer polymer of the core-shell particles includes one or more of polybutyl acrylate and polybutadiene rubber; the shell layer polymer of the core-shell particles includes one or more of polymethyl methacrylate and styrene-acrylonitrile copolymer.

[0062] In this invention, the glass transition temperature of the polyacrylic acid is approximately -54°C, and that of the polybutadiene rubber is approximately -85°C. These components remain highly elastic even in harsh winter conditions, contributing to the structural tape's durable toughness and initial tack. The glass transition temperature of the polymethyl methacrylate is approximately 105°C, and that of the styrene-acrylonitrile copolymer is approximately 100-120°C. These components remain glassy even in hot summer conditions, providing sufficient rigidity and thus offering a stable and reliable support effect for the structural tape.

[0063] In a preferred embodiment of the present invention, the core polymer of the core-shell particles is polybutyl acrylate, and the shell polymer is polymethyl methacrylate.

[0064] In this invention, both polybutyl acrylate (PBA) and polymethyl methacrylate (PMMA) contain polar ester groups, resulting in low interfacial energy. This facilitates the formation of a stable core-shell structure during emulsion polymerization, reducing the likelihood of phase separation. Furthermore, the polarity of PMMA (ester groups) is highly compatible with that of the epoxy resin, promoting better dispersion of core-shell particles within the epoxy matrix and enhancing interfacial bonding, thereby ensuring effective stress transfer. Both butyl acrylate and methyl methacrylate are commonly used acrylate monomers, with mature emulsion polymerization processes that allow for easy control of the core and shell dimensions, thickness, and crosslinking degree, offering good reproducibility and low cost.

[0065] In a preferred embodiment of the present invention, the method for preparing the core-shell particles includes: first, preparing a polybutyl acrylate seed emulsion; then, using the seed emulsion as a core, polymerizing on its surface to form a polymethyl methacrylate shell.

[0066] In a preferred embodiment of the present invention, the method for preparing the core-shell particles includes: S1. Preparation of core emulsion: By weight, add 80 parts butyl acrylate, 2 parts propylene glycol diester methacrylate, 1.5 parts sodium dodecyl sulfate and 150-200 parts water, and heat to 75-85°C under inert gas protection, and stir at 500 r / min for 30 min to form a uniform emulsion. While maintaining the temperature and stirring, add an initiator solution to the above homogeneous emulsion. The initiator solution is prepared by dissolving 0.3 parts of ammonium persulfate in 10-20 parts of water. Carry out the emulsion polymerization reaction at 75-85°C for 2-4 hours to obtain a polybutyl acrylate seed emulsion. S2. Shell coating polymerization In the polybutyl acrylate seed emulsion, under conditions of maintaining a temperature of 75°C to 85°C and stirring, the solution was added dropwise at a uniform rate through two constant-pressure dropping funnels. Solution A: Mix 20 parts methyl methacrylate, 0.5 parts propylene glycol diester methacrylate, 1 part glycidyl methacrylate, 0.2 parts sodium dodecyl sulfate, and 20-40 parts water, and stir at 500 r / min for 30 min to form a pre-emulsified monomer solution. Solution B: An initiator solution obtained by dissolving 0.3 parts potassium persulfate in 10-20 parts deionized water; Solution A and solution B are added simultaneously over 3 to 4 hours. After the addition is complete, the reaction is continued at 75 to 85°C for 1 to 2 hours to obtain the core-shell emulsion. S3. Post-processing: The core-shell emulsion obtained in step S2 is subjected to coagulation, filtration, washing, drying and deagglomeration to obtain core-shell particle powder.

[0067] In this invention, the inert gas is nitrogen.

[0068] The post-processing steps specifically include: Coagulation and washing: The obtained core-shell emulsion was cooled to room temperature, and a 5 wt% aluminum sulfate aqueous solution was added under stirring to demulsify until the polymer was completely precipitated. After filtration, the filter cake was repeatedly washed with deionized water until the washing liquid was neutral.

[0069] Drying: Place the washed filter cake in a vacuum drying oven at 80℃ and dry for 12 hours.

[0070] De-agglomeration: The dried blocky solid was placed in a vibrating grinder and treated at low frequency for 2 minutes, and then passed through a 400-mesh standard sieve to obtain a white powder of core-shell particles with good flowability.

[0071] In a preferred embodiment of the present invention, the core-shell particles are modified with a silane coupling agent, wherein the amount of the silane coupling agent is 1 to 5% of the mass of the core-shell particle powder.

[0072] Specifically, the method for modification using a silane coupling agent includes: dispersing 100 parts by weight of the above-mentioned core-shell particle powder in 200 parts by weight of ethanol, adding 1-5 parts by weight of silane coupling agent, and stirring and refluxing at 60°C for 3-5 hours. After the reaction is complete, the mixture is filtered, washed with ethanol, and dried at 80°C to obtain core-shell particles with a surface modified by the silane coupling agent.

[0073] The silane coupling agent includes KH560 and / or KH5680.

[0074] In this invention, by modifying the surface of the core-shell particles with a silane coupling agent, active groups can be introduced onto the surface of the core-shell particles, thereby establishing a strong chemical bridge between the core-shell particles and the epoxy resin matrix. This ensures that stress can be effectively transferred from the matrix to the elastic core of the core-shell particles when subjected to external forces. Good interfacial bonding also prevents the core-shell particles from loosening or detaching from the adhesive layer, ensuring the durability of the rigid shell layer as a micro-scaffold and its functional persistence. A dosage below 1% may result in incomplete modification and insufficient interfacial strengthening; a dosage above 5% is not only uneconomical, but excessive silane may also form a weak interfacial layer, negatively impacting performance.

[0075] In a preferred embodiment of the present invention, the toughening modified epoxy resin includes one or more of polyurethane modified epoxy resin, CTBN modified epoxy resin, and core-shell polymer pre-dispersed epoxy resin, preferably a core-shell polymer pre-dispersed epoxy resin. The core-shell polymer pre-dispersed epoxy resin can form a synergistic effect with the core-shell particles. The dual toughening system improves the peel strength of the tape, makes the cohesive strength more stable at high temperatures, and improves the initial tack and resistance to brittle fracture at low temperatures. It is also beneficial to maintain a balance between high strength and high toughness under high foaming ratio.

[0076] In this invention, the polyurethane-modified epoxy resin is preferably EPIKOTE RX-115 type polyurethane-modified epoxy resin from Hansen Chemical Company, the CTBN-modified epoxy resin is preferably the epoxy butadiene-nitrile prepolymer Gadida 861340, and the core-shell polymer pre-dispersed epoxy resin is preferably Kane Ace MX154 from Kaneka Chemicals, Japan.

[0077] In a preferred embodiment of the present invention, the curing agent is a latent curing agent, including one or more of dicyandiamide, sebacic acid dihydrazide or adipic acid dihydrazide, preferably dicyandiamide; the curing accelerator includes an organic urea accelerator, preferably complexed high-tech HUA5050 or PN50.

[0078] In a preferred embodiment of the present invention, the foaming agent includes azodicarbonamide; the foaming accelerator includes urea and zinc oxide.

[0079] In this invention, the mass ratio of urea to zinc oxide is (1~3):1, which can effectively adjust the decomposition temperature and decomposition rate of azodicarbonamide to match the curing exothermic peak of the epoxy resin system.

[0080] According to a second aspect of the present invention, a method for preparing a high-toughness structural adhesive tape as described above is provided, the method comprising: Heat the kneader to 70℃~80℃, add the solid epoxy resin, and after it is completely melted, add the carbon black, filler, desiccant, core-shell particles and fiber for mixing. After the mixture is uniform, add the liquid epoxy resin. Then, the toughening modified epoxy resin and silane coupling agent are added in sequence, and the mixture is stirred for 20-30 minutes after each addition; Finally, the curing agent, curing accelerator, foaming agent, and foaming accelerator are added, and the mixture is stirred evenly to obtain the adhesive material. The resulting material is then molded to obtain the structural tape.

[0081] In this invention, the preparation method specifically includes: (1) Heat the kneader to 70℃~80℃, add solid epoxy resin, and stir at low speed (10~30 rpm) until it is completely melted and transparent and homogeneous. Then, add carbon black, filler, desiccant, core-shell particles and fiber in sequence. Increase the speed of the kneader to 40~60 rpm and mix for 60~90 minutes under a vacuum of not less than -0.08 MPa until all powder components are completely coated by resin, forming a clump of rubber with uniform color and no visible powder particles.

[0082] (2) Cool the temperature of the above-mentioned uniformly mixed rubber system to below 60°C, and add liquid epoxy resin. Adjust the speed to 30~50 rpm and continue mixing for 20~30 minutes to make the system uniform.

[0083] (3) Keep the temperature below 60℃ and add the toughening modified epoxy resin and silane coupling agent in sequence. After each component is added, mix and stir at 30~50 rpm for 25±5 minutes to ensure uniform dispersion.

[0084] (4) Further reduce the temperature of the adhesive system to below 40°C. Add the curing agent, curing accelerator, foaming agent, and foaming accelerator. Maintain the rotation speed at 20-40 rpm and mix for 30-45 minutes under normal pressure or slight vacuum conditions until all newly added components are evenly dispersed to obtain the final adhesive. Throughout the final mixing process, the adhesive temperature should be monitored to avoid exceeding 50°C to prevent premature curing or decomposition of the foaming agent.

[0085] (5) Molding and Coating: The resulting rubber compound is transferred to a calender or extrusion coating equipment. The compound is calendered to the desired thickness (e.g., 0.5 to 2.0 mm) at a roll temperature or die temperature of 60°C to 80°C to obtain a high-toughness structural tape.

[0086] Then, release paper (isolation paper) can be covered on the surface of the adhesive film.

[0087] The high-toughness structural tape can be stored at room temperature, cut as needed when in use, and cured and foamed by baking at 180°C for 20 minutes to obtain the final product.

[0088] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0089] In the following embodiments, unless otherwise specified, all raw material components are commercially available products.

[0090] Example 1 An environmentally friendly, wide-temperature-range bonding, high-toughness structural tape, the raw material composition by weight is as follows: Solid epoxy resin: CYD-012, 25 parts Liquid epoxy resin: E-51, 18 parts Carbon black: N330, 5 parts Hardener: Dicyandiamide, 5 parts Curing accelerator: Complexed high-tech HUA5050, 0.5 parts Toughening modified epoxy resin: Gadida 861340, 35 parts Foaming agent: azodicarbonamide, 2.5 parts Foaming accelerator: 0.6 parts of a urea and zinc oxide complex in a 2:1 mass ratio. Fiber: Aramid chopped strand fiber, 0.5 mm in length, 1.5 parts Filler: Nano-calcium carbonate, 4.5 parts Desiccant: Calcium oxide, 1.5 parts Core-shell particles: The core layer is polybutyl acrylate, and the shell layer is polymethyl methacrylate; D50 = 12.5 μm; specific surface area = 1.79 m². 2 / g, 22 portions Silane coupling agent: KH-560, 0.15 parts Preparation of the core-shell particles: Preparation of S1 core emulsion: Add 80 parts butyl acrylate, 2 parts propylene glycol diester methacrylate, 1.5 parts sodium dodecyl sulfate and 180 parts water to the reactor, heat to 80°C under nitrogen protection, and stir at 500 r / min for 30 min to form a uniform emulsion.

[0091] While maintaining the temperature and stirring, add an initiator solution prepared by dissolving 0.3 parts of ammonium persulfate in 15 parts of water, and react at 80°C for 3 h to obtain polybutyl acrylate seed emulsion.

[0092] S2 shell coating polymerization: While maintaining a temperature of 80°C and stirring, add the following dropwise: Solution A: 20 parts methyl methacrylate, 0.5 parts propylene glycol diester methacrylate, 1 part glycidyl methacrylate, 0.2 parts sodium dodecyl sulfate and 30 parts water pre-emulsion; Solution B: An initiator solution prepared by dissolving 0.3 parts potassium persulfate in 15 parts water.

[0093] The dropping time was controlled at 3.5 h, and the reaction was kept at the temperature for 1.5 h after the dropping was completed to obtain a core-shell emulsion.

[0094] S3 Post-processing: The resulting core-shell emulsion was cooled to room temperature, and a 5 wt% aluminum sulfate aqueous solution was added with stirring to demulsify until the polymer was completely precipitated. After filtration, the filter cake was repeatedly washed with deionized water until the washing liquid was neutral.

[0095] The washed filter cake was placed in a vacuum drying oven at 80℃ and dried for 12 hours.

[0096] The dried blocky solid was placed in a vibrating mill and treated at a low frequency for 2 minutes, and then passed through a 400-mesh standard sieve to obtain a white powder of core-shell particles with good flowability.

[0097] S4 Surface Modification: Disperse 100 parts by weight of the above core-shell particle powder in 200 parts by weight of ethanol, add 1-5 parts by weight of silane coupling agent, and stir and reflux at 60°C for 3-5 hours. After the reaction is complete, filter, wash with ethanol, and dry at 80°C to obtain core-shell particles with surface modified by silane coupling agent.

[0098] Preparation of high-toughness structural tape: (1) Heat the kneader to 70℃~80℃, add solid epoxy resin, and stir at low speed (10~30rpm) until it is completely melted and transparent and homogeneous. Then, add carbon black, filler, desiccant, core-shell particles and fiber in sequence. Increase the speed of the kneader to 40~60rpm and mix for 60~90 minutes under a vacuum of not less than -0.08MPa until all powder components are completely coated by resin, forming a clump of rubber with uniform color and no visible powder particles.

[0099] (2) Cool the temperature of the above-mentioned uniformly mixed rubber system to below 60°C, and add liquid epoxy resin. Adjust the speed to 30~50 rpm and continue mixing for 20~30 minutes to make the system uniform.

[0100] (3) Keep the temperature below 60℃ and add the toughening modified epoxy resin and silane coupling agent in sequence. After each component is added, mix and stir at 30~50 rpm for 20~30 minutes to ensure uniform dispersion.

[0101] (4) Further reduce the temperature of the adhesive system to below 40°C. Add the curing agent, curing accelerator, foaming agent, and foaming accelerator. Maintain the rotation speed at 20-40 rpm and mix for 30-45 minutes under normal pressure or slight vacuum conditions until all newly added components are evenly dispersed to obtain the final adhesive. Throughout the final mixing process, the adhesive temperature should be monitored to avoid exceeding 50°C to prevent premature curing or decomposition of the foaming agent.

[0102] (5) Molding and Coating: The obtained rubber compound is transferred to a calender or extrusion coating equipment. The rubber compound is calendered into a high-toughness structural tape with a thickness of 1.0 mm at a roll temperature or die temperature of 60℃~80℃.

[0103] Then, release paper (isolation paper) is placed on the surface of the tape, and it is cooled by cooling rollers and then wound up.

[0104] The high-toughness structural tape is cut as needed during use and cured and foamed by baking at 180°C for 20 minutes.

[0105] Example 2 An environmentally friendly, wide-temperature-range bonding, high-toughness structural tape, the raw material composition by weight is as follows: Solid epoxy resin: CYD-011, 28 parts Liquid epoxy resin: E-44 type, 16 parts Carbon black: N550, 5 parts Hardener: Dicyandiamide, 5 parts Curing accelerator: PN50, 0.45 parts Toughening modified epoxy resin: Gadida 861340, 38 parts Foaming agent: azodicarbonamide, 2.2 parts Foaming accelerator: 0.7 parts of a urea and zinc oxide complex in a 2:1 mass ratio. Fiber: Aramid chopped strand fiber, 0.5 mm in length, 1.2 parts Filler: Talc powder, 4.5 parts Desiccant: Calcium oxide, 1.2 parts Core-shell particles: The core layer is polybutyl acrylate, and the shell layer is polymethyl methacrylate; D50 = 12.5 μm; specific surface area = 1.79 m². 2 / g, 25 portions Silane coupling agent: KH-550, 0.12 parts.

[0106] The preparation methods for core-shell particles and high-toughness structural tape are the same as in Example 1.

[0107] Example 3 An environmentally friendly, wide-temperature-range bonding, high-toughness structural tape, the raw material composition by weight is as follows: Solid epoxy resin: CYD-012, 22 parts Liquid epoxy resin: E-51, 19 parts Carbon black: N330, 5 parts Hardener: Dicyandiamide, 5 parts Curing accelerator: Complexed high-tech HUA5050, 0.5 parts Toughening modified epoxy resin: Kane Ace MX154 from Kaneka Chemicals, Japan, 32 parts Foaming agent: azodicarbonamide, 2.8 parts Foaming accelerator: 0.8 parts of a urea and zinc oxide complex in a 2:1 mass ratio. Fiber: Aramid chopped strand fiber, 0.5 mm in length, 1.8 parts per 100 mm. Filler: Nano-calcium carbonate, 3.5 parts Desiccant: Calcium oxide, 1.8 parts Core-shell particles: The core layer is polybutyl acrylate, and the shell layer is polymethyl methacrylate; D50 = 12.5 μm; specific surface area = 1.79 m². 2 / g, 20 portions Silane coupling agent: KH-560, 0.18 parts The preparation methods for core-shell particles and high-toughness structural tape are the same as in Example 1.

[0108] Example 4 The difference between Example 4 and Example 1 is that the toughening modified epoxy resin used is KaneAce MX154 from Kaneka Chemicals, Japan. Everything else is the same as in Example 1.

[0109] The preparation methods for core-shell particles and high-toughness structural tape are the same as in Example 1.

[0110] Example 5 The difference between Example 5 and Example 4 is that the S4 surface modification step is not performed in the preparation of the core-shell particles; otherwise, it is the same as Example 4.

[0111] Example 6 The difference between Example 6 and Example 4 is that 20 parts of the core-shell particles are used, while the rest is the same as in Example 4.

[0112] Example 7 The difference between Example 7 and Example 4 is that 25 parts of the core-shell particles are used, while the rest is the same as in Example 4.

[0113] Example 8 The difference between Example 8 and Example 4 is that 22 parts of solid epoxy resin and 18 parts of liquid epoxy resin are used, while the rest is the same as in Example 4.

[0114] Example 9 The difference between Example 9 and Example 4 is that 29 parts of solid epoxy resin and 18 parts of liquid epoxy resin are used, while the rest is the same as in Example 4.

[0115] Comparative Example 1 The difference between Comparative Example 1 and Example 4 is that core-shell particles are not used, and the preparation method of the high-toughness structural tape is the same as that of Example 4.

[0116] Comparative Example 2 The difference between Comparative Example 2 and Example 4 is that the amount of core-shell particles used is 15 parts, and the preparation methods of core-shell particles and high-toughness structural tape are the same as in Example 4.

[0117] Comparative Example 3 The difference between Comparative Example 3 and Example 4 is that the amount of core-shell particles used is 30 parts, and the preparation methods of core-shell particles and high-toughness structural tape are the same as in Example 4.

[0118] Comparative Example 4 The difference between Comparative Example 4 and Example 4 is that Kane Ace MZ100 from Kaneka Chemicals of Japan was used as the core-shell particle; otherwise, they are the same as in Example 4.

[0119] Performance testing 1. Core-shell particle characterization as described in Example 1 (1) Particle size distribution and specific surface area The particle size distribution was measured using a Truth Optics LT2200 laser particle size analyzer, as shown in the following figure. Figure 1 As shown.

[0120] The specific surface area (SSA) is as follows: D5: 26.560 μm, D10: 23.315 μm, D50: 12.481 μm, D90: 1.586 μm, D95: 0.568 μm, 1.79 m². 2 / g.

[0121] (2) Infrared spectrum Fourier transform infrared spectroscopy was used, employing the KBr pellet method, to analyze functional groups after scanning. The infrared spectrum is shown below. Figure 2 As shown.

[0122] 2800~3000 cm -1 The region represents the absorption peak of the saturated CH stretching vibration, corresponding to the sp(s) of the alkyl chains (-CH2-, -CH3) in polybutyl acrylate (core layer) and polymethyl methacrylate (shell layer). 3 CH bond stretching vibration.

[0123] 1730cm -1 The nearby region is an absorption peak of the C=O stretching vibration of the ester group, which is a characteristic stretching vibration peak of the C=O double bond of the ester group in butyl acrylate and methyl methacrylate.

[0124] 1000~1300cm -1 The region is a superposition of CO / COC / Si-O vibrational absorption peaks, containing vibrations of three types of functional groups: COC single bond stretching vibration of ester group; characteristic vibration of epoxy group introduced by glycidyl methacrylate; and Si-O bond stretching vibration introduced by silane coupling agent modification.

[0125] 1400~1500cm -1 The region represents the absorption peak of the CH bending vibration, corresponding to the -CH2- and -CH3- bending vibrations of the alkyl chain.

[0126] (3) Thermogravimetric analysis Using a thermogravimetric analyzer, take 5-10 mg of sample and heat it from room temperature to 800℃ at a rate of 15℃ / min under a nitrogen atmosphere (flow rate 50 mL / min), and record the mass-temperature curve.

[0127] Thermogravimetric analysis diagram as follows Figure 3 As shown.

[0128] At temperatures below 300℃, the residual mass remained above 95%, with only very slight weight loss, indicating that moisture and low-boiling-point impurities were basically removed after vacuum drying at 80℃; the core-shell particles have good thermal stability below 300℃.

[0129] The main weight loss stage is between 350 and 500°C, during which significant weight loss occurs, with the residual mass decreasing from nearly 100% to below 5%, corresponding to the thermal decomposition process of polybutyl acrylate (core layer) and polymethyl methacrylate (shell layer).

[0130] At temperatures above 500℃, the residual mass is close to 0, indicating that the core-shell particles are pure organic polymers with no inorganic filler residue and complete thermal decomposition, which is consistent with the thermal behavior characteristics of "acrylate core-shell particles".

[0131] 2. Tape performance test (1) Penetration (before tape curing) Test standard: Refer to GB / T 4509-2010 (Asphalt Penetration Test Method) Test method: Place the rubber compound in a specified container and, at a constant temperature of 25°C, use a standard needle (total weight 100g) to vertically penetrate the rubber compound to the desired depth within 5 seconds.

[0132] (2) Expansion ratio Test method: 25 × 25 × 2t tape-shaped sample, the thickness is measured with calipers, and then the sample is placed on a steel plate and cured at 180℃ for 20 minutes. After curing, the sample is dried at room temperature and the thickness after curing is measured to calculate the foaming ratio.

[0133] (3) Shear strength Testing standard: Refer to GB / T 7124-2008 Test method: Prepare stainless steel lapped specimens according to the standard (lap area 25mm×12.5mm, tape thickness 1mm), cure at 180℃ for 20min, and test the shear strength at a speed of 5mm / min on a tensile testing machine according to GB / T 7124-2008, and observe the fracture mode.

[0134] (4) Peel strength Test standard: Refer to GB / T 2791-1995 Test method: Prepare stainless steel lapped specimens (lap area 25mm×12.5mm, tape thickness 1mm) according to the standard. After curing at 180℃ for 20min, test the peel strength on a tensile testing machine at a speed of 50mm / min in accordance with GB / T 2791-1995.

[0135] The test results for penetration, foaming ratio, shear strength, and peel strength are shown in Table 1. Table 1. Test results of penetration, foaming ratio, shear strength, and peel strength.

[0136] As shown in Table 1, the penetration reflects the hardness and fluidity of the adhesive before curing. The smaller the value, the less likely the adhesive is to over-penetrate the release paper. In each embodiment, the rigid shell layer of the core-shell particles forms physical support at room temperature, constraining the movement of polymer chain segments, resulting in moderate hardness of the adhesive and avoiding excessive fluidity. The penetration is 42-47 mm. In Comparative Example 1, without core-shell particles, the adhesive lacks rigid support, allowing the polymer chain segments to move freely, resulting in extremely high fluidity. The penetration is 54 mm, and it easily penetrates the release paper at high temperatures. In Comparative Example 3, the amount of core-shell particles is 30 parts in excess. Particle agglomeration disrupts the continuity of the matrix, causing localized hardening of the adhesive. The penetration is 42 mm, but the overall uniformity is poor.

[0137] The expansion ratio reflects the stability of the cell structure after curing. A reasonable expansion ratio (250%~300%) can achieve a balance between lightweighting and structural strength. In Examples 1-9, the core-shell particles act as "cell stabilizers," uniformly dispersed in the adhesive, preventing the coalescence or collapse of bubbles generated by the decomposition of the foaming agent at high temperatures. Therefore, the expansion ratio is stable at 260%~285%, forming a uniform closed-cell structure. In Comparative Example 1, without core-shell particles, the bubbles are unsupported and easily escape, resulting in an expansion ratio of only 142%, which cannot achieve effective lightweighting. In Comparative Example 3, with excessive core-shell particles, particle aggregation leads to localized over-expansion of bubbles, resulting in an expansion ratio of 338%, and the excessively large cells lose their structural support capacity.

[0138] Shear strength reflects the structural load-bearing capacity after tape bonding, and both strength and toughness must be considered. In Examples 1-9, the core-shell particles and epoxy resin matrix work synergistically; the rigid shell layer enhances the matrix strength, while the elastic core layer absorbs stress, resulting in moderate shear strength (3.2-3.7 MPa), with most fractures being ductile fractures. In Comparative Example 1, without core-shell particles, the matrix is ​​rigid but lacks toughness; although the shear strength is high (4.9 MPa), the fracture is brittle, making it prone to detachment in practical applications. In Comparative Example 3, excessive core-shell particles cause particle aggregation, disrupting the matrix continuity, and the shear strength drops sharply to 2.4 MPa, failing to meet the structural load-bearing requirements.

[0139] Peel strength reflects the interfacial adhesion toughness of the tape; the higher the value, the stronger the resistance to peeling and cracking. In Examples 1-9, the elastic core layer generates crazing and shear bands during peeling, absorbing peeling energy, thus resulting in significantly higher peel strength than the comparative examples. In Example 4, the core-shell toughening epoxy resin works synergistically, and the dual toughening system further enhances toughness, achieving a peel strength of 3.2 MPa. In Comparative Examples 1 and 3, the lack of core-shell particles or particle agglomeration leads to insufficient toughness, with a peel strength of only 1.7 MPa, making interfacial debonding prone to occur.

[0140] (5) High-temperature peel force test Test standard: Refer to GB / T 2791-1995 "Adhesives T - Peel strength test method - Flexible materials vs. rigid materials", and adjust the temperature conditions accordingly.

[0141] Test method: Cut a 25mm×200mm tape sample (retain the release paper), attach the adhesive side of the tape to a standard stainless steel plate (100mm×300mm×1.6mm, clean and free of oil), and roll it back and forth 3 times with a 2kg roller to ensure that the tape is pre-bonded to the steel plate and does not cure.

[0142] The bonded samples were placed in a constant temperature chamber and kept at 35℃, 40℃, and 45℃ for 1 hour respectively.

[0143] Immediately after removal, peel the release paper off the tensile testing machine at a speed of 50 mm / min in a 180° direction and record the maximum peel force during the peeling process (unit: N / 25 mm).

[0144] (6) Low temperature initial tack test Test standard: Refer to GB / T 4852-2002 "Test method for initial tack of pressure-sensitive adhesive tape (rolling ball method)" and adjust the temperature conditions.

[0145] Test method: Cut a 25mm×100mm tape sample, flatten it and attach it to a standard stainless steel plate (surface roughness Ra=0.8μm), roll it back and forth once with a 1kg roller, and remove the release paper.

[0146] The bonded samples were placed in a constant temperature chamber and kept at 0℃, -5℃, and -10℃ for 30 minutes respectively.

[0147] Immediately after removal, use the rolling ball method: roll a steel ball (100g, 10mm in diameter) from the 30° inclined sample surface and record the rolling distance of the steel ball on the tape (unit: mm); or use the "ring initial tack" test (refer to ASTM D3121) and record the force required to peel off the ring steel sheet (unit: N).

[0148] (7) Low-temperature shear strength test Test standard: Refer to GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)", and adjust the temperature conditions.

[0149] Stainless steel lap joint samples (lap area 25mm×12.5mm, tape thickness 1mm) were prepared according to the standard. After curing at 180℃ for 20min, they were placed in a constant temperature chamber and kept at 0℃, -5℃, and -10℃ for 2h.

[0150] Immediately after removal, test the shear strength on a tensile testing machine at a speed of 5 mm / min and observe the fracture mode.

[0151] The test results of high temperature peel force, low temperature initial tack force, and low temperature shear strength are shown in Table 2.

[0152] Table 2. Test results of high-temperature peel strength, low-temperature initial tack, and low-temperature shear strength.

[0153] As shown in Table 2, the high-temperature peel force reflects the ease of peeling off the release paper in summer (35~45℃), with a smaller value indicating easier construction. In Examples 1-9, the rigid shell layer of the core-shell particles forms a "microscopic scaffold" at high temperatures, reducing the effective contact area between the adhesive and the release paper, while also restricting the flow and penetration of the adhesive. Therefore, the peel force is extremely low, only 0.5~0.8 N / 25mm at 35℃, which solves the problem of "difficulty in peeling off the paper". In Comparative Example 1, without core-shell particles, the adhesive softens and penetrates the micropores of the release paper at high temperatures, resulting in a peel force of 2.8~4.2 N / 25mm. During construction, it is prone to stringing and deformation of the adhesive layer. In Comparative Example 2, the amount of core-shell particles is insufficient, resulting in insufficient scaffold effect. The peel force is 0.9 N / 25mm at 35℃, which is higher than that of the Examples. In Comparative Example 3, particle agglomeration leads to uneven distribution of the scaffold, and the peel force rises back to 1.8~2.9 N / 25mm.

[0154] Low-temperature initial tack reflects the initial adhesion ability of the tape in winter (-10~0℃). The shorter the ball distance, the stronger the initial tack. In Examples 1-9, the core layer elastomer maintains high elasticity at low temperatures. The core-shell particles act as "microscopic pressure heads," applying localized high pressure to the adhesive material under external force, promoting the adhesive material's wetting of the microscopic unevenness of the adhered surface. Therefore, the ball distance is short (15~22mm at 0℃, 52~65mm at -10℃), quickly establishing initial adhesion. In Comparative Example 1, without core-shell particles, the adhesive material is in a glassy state at low temperatures and cannot wet the adhered surface, with a ball distance of 75~120mm. In Comparative Example 2, the amount of core-shell particles is insufficient, resulting in a weak microscopic pressure head effect, and the ball distance (25mm at 0℃) is longer than in Examples 1. In Comparative Example 3, particle agglomeration leads to a decrease in adhesive toughness, and the ball distance (65mm at 0℃) is close to that of Comparative Example 1.

[0155] Low-temperature shear strength reflects the bonding reliability at low winter temperatures; the higher the value, the stronger the resistance to brittle fracture and detachment. In Examples 1-9, the elastic core layer acts as a stress concentration point at low temperatures, inducing crazes and shear bands in the matrix, absorbing impact energy and preventing brittle fracture of the adhesive layer, thus resulting in high shear strength (1.7-2.1 MPa even at -10℃). In Comparative Example 1, without core-shell particles, the adhesive is hard and brittle at low temperatures, with a shear strength of only 0.8-1.8 MPa, making it prone to fracture and failure. In Comparative Example 2, insufficient particles result in insufficient toughening effect, with a shear strength of 1.5 MPa at -10℃. In Comparative Example 3, agglomerated particles become stress concentration points, exacerbating brittle fracture, with a shear strength of only 0.6 MPa at -10℃.

[0156] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, nor does it mean that the present invention must rely on the above process steps for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An environmentally friendly high-toughness structural adhesive tape with a wide temperature range bonding, characterized in that, The high-toughness structural adhesive tape comprises the following raw materials in parts by weight: 20-30 parts of solid epoxy resin, 15-20 parts of liquid epoxy resin, 30-40 parts of toughening modified epoxy resin, 20-25 parts of core-shell particles, 4-6 parts of curing agent, 0.4-0.6 parts of curing accelerator, 2-3 parts of foaming agent, 0.4-0.8 parts of foaming accelerator, 4-6 parts of carbon black, 1-2 parts of fiber, 3-6 parts of filler, 1-2 parts of moisture absorbent, 0.1-0.2 parts of silane coupling agent; The core-shell particles are polymer microparticles with a core-shell structure, the core layer is an elastic polymer with a glass transition temperature lower than -20 DEG C, and the shell layer is a rigid polymer with a glass transition temperature higher than 60 DEG C; the volume-weighted median particle size D50 of the core-shell particles is 10-15 mu m, and the specific surface area thereof is greater than 1.5 m 2 / g.

2. The high-toughness structural tape of claim 1, wherein The span of particle size distribution (D90-D10) / D50 of the core-shell particles is 1.5-2.

3. The high-toughness structural tape of claim 1, wherein The core-shell particles have a core layer polymer comprising one or more of polybutyl acrylate, polybutadiene rubber, silicone rubber and polyurethane elastomer, and a shell layer polymer comprising one or more of polymethyl methacrylate, polystyrene, polyethyl methacrylate and styrene-acrylonitrile copolymer.

4. The high-toughness structural tape of claim 3, wherein The core layer polymer of the core-shell particles is polybutyl acrylate, and the shell layer polymer is polymethyl methacrylate.

5. The high-toughness structural tape of claim 4, wherein, The preparation method of the core-shell particles comprises: S1. Preparation of core layer emulsion: 80 parts of butyl acrylate, 2 parts of propylene glycol dimethacrylate, 1.5 parts of sodium dodecyl sulfate and 150-200 parts of water are added, and the temperature is raised to 75-85°C under inert gas protection, and a uniform emulsion is formed under stirring at 500 r / min for 30 min; The temperature and stirring are maintained, and an initiator solution is added to the above uniform emulsion, wherein the initiator solution is prepared by dissolving 0.3 parts of ammonium persulfate in 10-20 parts of water; the emulsion polymerization reaction is carried out at 75-85°C for 2-4 hours to obtain a polybutyl acrylate seed emulsion; S2. Shell coating polymerization Under the conditions of maintaining 75-85°C and stirring, the following are uniformly and continuously added through two constant-pressure dropping funnels: A liquid: 20 parts of methyl methacrylate, 0.5 parts of propylene glycol dimethacrylate, 1 part of glycidyl methacrylate, 0.2 parts of sodium dodecyl sulfate and 20-40 parts of water are mixed to form a pre-emulsified monomer liquid under stirring at 500 r / min for 30 min; B liquid: an initiator solution obtained by dissolving 0.3 parts of potassium persulfate in 10-20 parts of deionized water; The addition of A liquid and B liquid is completed simultaneously within 3-4 hours, and after the addition is completed, the reaction is continued at 80°C for 1-2 hours to obtain a core-shell structure emulsion; S3. Post-treatment: the core-shell emulsion obtained in step S2 is subjected to coagulation, filtration, washing, drying and deagglomeration to obtain a core-shell particle powder.

6. The high-toughness structural tape according to any one of claims 1-5, wherein, The core-shell particles are modified using a silane coupling agent, and the amount of the silane coupling agent is 1-5% of the mass of the core-shell particle powder.

7. The high-toughness structural tape of claim 1, wherein The toughening modified epoxy resin comprises one or more of polyurethane modified epoxy resin, CTBN modified epoxy resin and core-shell polymer pre-dispersed epoxy resin.

8. The high-toughness structural tape of claim 1, wherein, The curing agent comprises one or more of dicyandiamide, decanedioic acid dihydrazide or adipic acid dihydrazide; and the curing accelerator comprises an organic urea accelerator.

9. The high-toughness structural tape of claim 1, wherein, The foaming agent comprises azodicarbonamide; the foaming promoter comprises urea and zinc oxide.

10. A method of producing the high-toughness structural adhesive tape according to any one of claims 1 to 9, characterized by, The method comprises the following steps: The kneader is heated to 70-80 DEG C, the solid epoxy resin is added, and after complete melting, the carbon black, filler, moisture absorbent, core-shell particle and fiber are mixed, and after uniform mixing, the liquid epoxy resin is added; Then, the toughening modified epoxy resin and silane coupling agent are added in sequence, and after each addition, mixing and stirring are performed for 20-30 min; Finally, the curing agent, curing promoter, foaming agent and foaming promoter are added, and after uniform stirring, the glue is obtained, and the structural adhesive tape is formed.

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