A low-odor, moisture-resistant foamed reinforcing film and its preparation method

Abstract

This invention discloses a low-odor, moisture-resistant foamed reinforcing film and its preparation method, belonging to the field of high-performance composite material technology. The film's main components are an epoxy resin modifier, rubber masterbatch, Janus core-shell tackifying resin, foaming agent, curing accelerator, amine crosslinking agent, and filler. The epoxy resin modifier is formed by reacting a fluorinated polyether polyol with isocyanate to form a prepolymer, which then reacts with the epoxy resin molecular chain to form a block graft copolymer, thereby significantly improving the material's hygrothermal stability and interfacial bonding strength. By introducing an amphiphilic Janus core-shell tackifying resin and an inorganic filler treated with a silane coupling agent, this invention enables the material to exhibit excellent mechanical reinforcement and dimensional stability after foaming and curing, while effectively reducing the irritating odor generated during the curing process of traditional foamed films.

Description

Technical Field

[0001] This invention relates to the field of high-performance composite materials technology, and in particular to a low-odor, moisture-resistant foamed reinforcing film and its preparation method. Background Technology

[0002] Currently, foamed reinforcing films are widely used in lightweight automotive structural components, vehicle body vibration damping and noise reduction layers, and reinforcement connections in building structures. These films typically use epoxy resin or rubber resin as a matrix, adding a foaming agent and forming a lightweight material with a microporous structure under heat treatment. This reduces weight while maintaining structural strength, and also provides sound insulation, sealing, and impact resistance. However, existing foamed reinforcing films still face a series of technical bottlenecks affecting performance and environmental friendliness during long-term use. First, traditional epoxy-rubber composite systems release large amounts of organic amines and benzene volatiles during thermosetting. These substances not only cause odor pollution in the vehicle interior and construction environment but may also cause discomfort to operators and pose environmental safety hazards. Second, ordinary epoxy systems are extremely sensitive to humidity, easily experiencing water absorption and swelling, interface debonding, and decreased mechanical properties in high-humidity environments, leading to reduced bonding reliability. Third, due to the multiple influences of resin polarity, gas diffusion, and crosslinking density during the foaming process, existing materials often struggle to achieve a uniform and stable cell structure while maintaining excellent mechanical strength. Especially in automotive body reinforcement applications, uneven pore size distribution of the foam layer or aging of the bonding interface can directly affect the torsional stiffness of the body and collision safety.

[0003] Therefore, this invention is proposed. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a low-odor, moisture-resistant foamed reinforcing film and its preparation method. This invention introduces an amphiphilic Janus core-shell structure tackifying resin and an inorganic filler treated with a silane coupling agent, resulting in a material with excellent mechanical reinforcement and dimensional stability after foaming and curing. Simultaneously, it effectively reduces the irritating odor generated during the curing process of traditional foamed films.

[0005] In order to achieve the objective of this invention, the following technical solution is adopted:

[0006] This invention provides a low-odor, moisture-resistant foamed reinforcing film, which, by weight, comprises the following raw materials:

[0007] 50-80 parts of epoxy resin modifier;

[0008] 80-120 parts of rubber masterbatch;

[0009] 5-15 parts of Janus core-shell structure tackifying resin;

[0010] 3-8 parts of foaming agent;

[0011] Curing accelerator 0.5-2 parts;

[0012] 5-15 parts of amine crosslinking agent;

[0013] 40-80 parts of filler;

[0014] The epoxy resin modifier is a block graft copolymer formed by reacting fluorinated polyether polyol with isocyanate to obtain an isocyanate-terminated prepolymer, and then reacting it with the secondary hydroxyl groups of the epoxy resin molecular chain.

[0015] Furthermore, the epoxy resin is bisphenol A type epoxy resin E-51 or epoxy resin E-128.

[0016] Furthermore, the fluorinated polyether polyol has a molecular weight of 500-2000, and the isocyanate is isophorone diisocyanate.

[0017] Furthermore, the rubber masterbatch is obtained by mixing butadiene rubber and styrene-butadiene rubber in a mass ratio of (1:1) to (2:1).

[0018] Furthermore, the foaming agent is 4,4'-oxobisbenzenesulfonylhydrazine.

[0019] Furthermore, the Janus core-shell structure tackifying resin is composed of an oleophilic core and a hydrophobic shell, wherein the core is a hydrogenated petroleum resin or a polyolefin oligomer, and the shell is a reactive organosilicon or a fluorinated oligomer.

[0020] Furthermore, the filler is talc or wollastonite powder treated with a silane coupling agent.

[0021] Furthermore, the curing accelerator is 2-phenylimidazole.

[0022] Furthermore, the amine crosslinking agent is adipic acid dihydrazide.

[0023] This invention also provides a method for preparing a low-odor, moisture-resistant foamed reinforcing film, comprising the following steps:

[0024] Epoxy resin modifiers and rubber masterbatches were prepared separately.

[0025] Add rubber masterbatch, epoxy resin modifier, foaming agent, curing accelerator, amine crosslinking agent, Janus core-shell structure tackifying resin and filler in sequence, and mix evenly to obtain a mixture;

[0026] The resulting mixture is extruded or calendered into sheets 1.0-2.0 mm thick, covered with fiberglass cloth, and cut to obtain a low-odor, moisture-resistant foamed reinforcing film.

[0027] The present invention has the following technical effects:

[0028] This invention reacts fluorinated polyether polyols with isophorone diisocyanate to generate a prepolymer with excellent flexibility and hydrophobic properties, which is then copolymerized with epoxy resin molecular chains to construct a block graft system with both polar and nonpolar structural units, thereby improving the material's compatibility and moisture resistance at the molecular level. Simultaneously, a Janus core-shell structure tackifying resin with an amphiphilic interface is used to form an adaptive interfacial transition layer between the polar epoxy body and the nonpolar rubber phase. This not only significantly enhances the initial tack and post-curing adhesion of the film but also reduces the release of small molecules during curing, achieving a synergistic effect of low odor and high adhesion. Furthermore, by selecting inorganic fillers modified with silane coupling agents and a specific ratio of rubber masterbatch system, an integrated design of gas control and mechanical reinforcement during the foaming process is achieved, resulting in a foamed layer with uniform pore size and high dimensional stability. Compared with traditional technologies, the structure of this invention is structurally stable, and the cured material maintains high bonding strength and dimensional retention even under high humidity and heat conditions, solving the problem of performance degradation caused by humidity or aging in previous foamed reinforcing films. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] In a first aspect, the present invention provides a low-odor, moisture-resistant foamed reinforcing film, wherein, by weight parts, the foamed reinforcing film comprises the following raw materials: 50-80 parts of epoxy resin modifier; 80-120 parts of rubber masterbatch; 5-15 parts of Janus core-shell structure tackifying resin; 3-8 parts of foaming agent; 0.5-2 parts of curing accelerator; 5-15 parts of amine crosslinking agent; and 40-80 parts of filler; wherein the epoxy resin modifier is a block graft copolymer formed by reacting fluorinated polyether polyol with isocyanate to obtain an isocyanate-terminated prepolymer, and then reacting it with the secondary hydroxyl groups of the epoxy resin molecular chain.

[0031] This invention achieves synergistic regulation of the polarity, flexibility, and hygrothermal stability of the epoxy system by introducing an isocyanate-terminated prepolymer formed by the reaction of fluorinated polyether polyol and isocyanate, followed by a reaction with the secondary hydroxyl groups of the epoxy resin molecular chain to generate a block graft copolymer. Simultaneously, through the organic combination with rubber masterbatch, Janus core-shell tackifying resin, specific foaming agent, and coupled inorganic fillers, a systematically optimized balance is achieved in terms of low odor, high moisture resistance, high adhesion, and foaming uniformity of the foamed reinforcing film. The technical solution of this invention overcomes several key defects of traditional epoxy-rubber foaming systems, exhibiting outstanding stability and environmental friendliness, especially in long-term service environments such as vehicle body structural reinforcement, building sealing, and electronic packaging.

[0032] Specifically, the core of the foamed reinforcing film of this invention lies in the structural control of the epoxy resin modifier. Traditional foamed films typically use direct physical blending of epoxy resin with rubber or tackifying resin. While this method can improve flexibility to some extent, poor polar compatibility leads to phase separation during curing and foaming, affecting the uniformity of the cell structure and interfacial adhesion. This invention utilizes the reaction of fluorinated polyether polyol with isocyanate to form a prepolymer, which is then reacted with epoxy resin molecular chains. The resulting block graft copolymer achieves a balanced distribution of polar and non-polar groups at the molecular level, resulting in excellent macroscopic compatibility and microscopic interfacial stability. Fluorinated polyether polyols are rich in CF bonds and COC segments, which endow them with low surface energy, high hydrophobicity, and strong flexibility. When reacting with isocyanates, the isocyanate groups (-NCO) undergo an addition reaction with hydroxyl groups (-OH) to form urethane bonds (-NH-CO-O-). The resulting prepolymer retains unreacted -NCO groups at its ends, which will serve as active sites for reaction with epoxy resin in subsequent steps. When the prepolymer containing -NCO end groups is blended with epoxy resin, the hydroxyl groups remaining at the ends or between molecules of the epoxy molecule can further undergo addition reactions with the isocyanate groups to form new urethane bonds or urea structures, thereby allowing the fluorinated polyether segments to be chemically grafted onto the epoxy resin molecular chain. This process not only achieves block copolymerization of polar epoxy segments and nonpolar fluorinated flexible segments at the molecular level, but also, due to the unidirectional and highly selective reaction pathway, results in a highly uniform molecular structure and strong chemical bonds in the product, avoiding the drawbacks of phase separation or delamination that are common in traditional physical blending systems. Macroscopically, this block graft structure significantly improves the system's compatibility, enhances dispersion uniformity, and strengthens interfacial bonding, thus providing a foundation for the material's high mechanical properties and excellent foaming structure.

[0033] Secondly, this invention employs a composite system of butadiene rubber and styrene-butadiene rubber, enabling the material to maintain high thermal stability while possessing good flexibility. After being mixed in a specific mass ratio, the film retains a continuous and uniform cell structure and excellent resilience after foaming, ensuring its stable reinforcement effect in vehicle body cavities or complex structural components. Furthermore, the foaming agent selected in this invention is 4,4'-oxobisbenzenesulfonyl hydrazine. This compound produces a stable and clean gas upon thermal decomposition, without generating an irritating odor. Simultaneously, the amount of gas released is moderate, matching the crosslinking rate of the system, ensuring uniform and fine cell structure and preventing collapse. This is crucial for controlling low odor and foaming stability.

[0034] In terms of interface enhancement design, this invention employs a Janus core-shell structure tackifying resin. Traditional tackifying resins are typically single-phase organic systems, whose molecular structures cannot simultaneously accommodate the interface between polar resins and non-polar rubbers, easily leading to interfacial delamination or stress concentration. However, the Janus core-shell structure tackifying resin material, through its amphiphilic design—a lipophilic core as support and an outer hydrophobic or reactive shell—allows it to automatically orient itself at the epoxy-rubber interface at the molecular level, thus forming a flexible transition layer during curing. This unique molecular orientation effect not only significantly enhances the interfacial adhesion of the system but also slows down the propagation of microcracks caused by stress concentration, improving the long-term fatigue life of the material. Simultaneously, the Janus core-shell structure tackifying resin releases almost no small-molecule byproducts at high temperatures, thus effectively reducing odor sources while maintaining high bond strength, further refining the path to achieving low-odor performance.

[0035] Regarding the selection of fillers, talc or wollastonite powder treated with silane coupling agents can chemically bond with the hydroxyl or epoxy groups in epoxy resin, thereby forming a stable skeletal support structure after foaming, significantly improving the dimensional uniformity and compressive strength of the cells. Surface modification with silane coupling agents further enhances the compatibility between the filler and the organic matrix, preventing filler agglomeration or detachment, and significantly improving the mechanical strength and moisture resistance of the foamed layer. Furthermore, the synergistic effect of the curing accelerator 2-phenylimidazolium and the amine crosslinking agent adipate dihydrazide accelerates the curing reaction of epoxy groups while forming a dense crosslinked network. This ensures complete curing of the system while controlling the release of low-molecular-weight substances during curing. This reaction control strategy is the key chemical basis for achieving low odor and high structural stability.

[0036] In some embodiments, the epoxy resin is bisphenol A type epoxy resin E-51 or epoxy resin E-128.

[0037] In some embodiments, the molecular weight of the fluorinated polyether polyol is 500-2000, and the isocyanate is isophorone diisocyanate.

[0038] In some embodiments, the rubber masterbatch is obtained by mixing butadiene rubber and styrene-butadiene rubber in a mass ratio of (1:1) to (2:1).

[0039] Butadiene rubber, a highly polar rubber material, contains cis-butadiene groups in its molecular chain. The introduction of butadiene rubber ensures the interfacial properties and adhesion of the film. Butadiene rubber also exhibits good moisture resistance, effectively resisting the effects of humidity and preventing expansion and interfacial peeling in long-term humid environments, thus extending the film's service life. On the other hand, styrene-butadiene rubber, a non-polar rubber, possesses good toughness and elasticity, and relatively high thermal stability. Its role in the system is to enhance the film's flexibility and impact resistance, especially in its reinforcing effect after foaming. Styrene-butadiene rubber effectively enhances the structural toughness of the foam layer, preventing the rupture or collapse of the pore structure during the foaming process.

[0040] By appropriately blending butadiene rubber and styrene-butadiene rubber, the resulting rubber masterbatch maintains good flexibility while improving the material's hygrothermal stability, especially in high-humidity environments, ensuring the strength and adhesion of the film. This flexible blending allows the foamed reinforcing film to be widely used for bonding needs in various environments, including automotive manufacturing, building structure reinforcement, and other industrial applications.

[0041] In some embodiments, the foaming agent is 4,4'-oxobis(benzenesulfonyl)hydrazine.

[0042] In some embodiments, the Janus core-shell structure tackifying resin is composed of an oleophilic core and a hydrophobic shell, wherein the core is a hydrogenated petroleum resin or a polyolefin oligomer, and the shell is a reactive organosilicon or a fluorinated oligomer.

[0043] This invention constructs an amphiphilic core-shell structure at the molecular level, enabling the tackifying resin to form an energy transition layer between the polar epoxy phase and the non-polar rubber phase, thereby significantly improving the interfacial bonding strength, structural stability, and environmental adaptability of the system. The Janus core-shell structure tackifying resin consists of an oleophilic core and a hydrophobic shell, wherein the core is selected from hydrogenated petroleum resin or polyolefin oligomers, and the shell is a reactive organosilicon or a fluorinated oligomer.

[0044] In traditional foamed reinforcing film systems, tackifying resins often employ a single-phase structure with molecular polarity biased to one side. This leads to polarity mismatch at the interface, resulting in phase separation, interfacial debonding, or stress concentration, ultimately affecting the overall mechanical properties and service life of the material. Janus core-shell structured tackifying resins, with their amphiphilic molecular configuration, achieve simultaneous compatibility of polar and non-polar phases. The core lies in the oleophilic core, which can undergo van der Waals interactions and chain entanglement with the rubber masterbatch at the molecular scale, thus firmly embedding itself into the non-polar matrix. Meanwhile, the reactive organosilicon or fluorinated oligomers in the hydrophobic shell can chemically react or interact with the polar groups in the epoxy resin molecular chains or modifiers, forming strong interfacial bonds. This core-shell molecular orientation allows the tackifying resin to spontaneously align at the epoxy-rubber interface during curing. Its "two-sided" molecular structure forms a natural interfacial transition layer, avoiding energy discontinuities caused by polarity abrupt changes while ensuring the overall system's compatibility and structural stability.

[0045] On the other hand, the design of this Janus core-shell structure tackifying resin fundamentally solves the odor problem commonly found in traditional epoxy systems. In conventional tackifier systems, polar solvents or low-molecular-weight additives often release volatile compounds such as amines, alcohols, or esters during the curing process, resulting in a noticeable odor in the finished film. Therefore, the Janus core-shell structure provided by this invention, due to its use of a polymeric reactive shell, contains almost no low-molecular-weight volatile components, and the reaction process is a cross-linking curing process between polymer chains rather than a low-molecular-weight chemical reaction, thus greatly reducing VOC emissions and achieving low-odor performance control from the source. Simultaneously, the dense outer layer formed by the fluorinated or silicone shell after curing further prevents the escape of residual small molecules, thereby maintaining excellent environmental performance even after curing.

[0046] In some embodiments, the filler is talc or wollastonite powder treated with a silane coupling agent.

[0047] In some embodiments, the curing accelerator is 2-phenylimidazole.

[0048] In some embodiments, the amine crosslinking agent is adipic acid dihydrazide.

[0049] Secondly, the present invention also provides a method for preparing a low-odor, moisture-resistant foamed reinforcing film, comprising the following steps:

[0050] Epoxy resin modifiers and rubber masterbatches were prepared separately.

[0051] Add rubber masterbatch, epoxy resin modifier, foaming agent, curing accelerator, amine crosslinking agent, Janus core-shell structure tackifying resin and filler in sequence, and mix evenly to obtain a mixture;

[0052] The resulting mixture is extruded or calendered into sheets 1.0-2.0 mm thick, covered with fiberglass cloth, and cut to obtain a low-odor, moisture-resistant foamed reinforcing film.

[0053] The following is a detailed explanation using specific embodiments:

[0054] Example 1

[0055] The epoxy resin E-51 used in this embodiment is bisphenol A type with an epoxy value of 0.51, and was purchased from Bluestar Chemical New Materials Co., Ltd.

[0056] The catalyst was dibutyltin dilaurate, purchased from Momentive Performance Materials.

[0057] Janus core-shell structure tackifying resin has a core of hydrogenated petroleum resin and a shell of reactive organosilicon. The core material was purchased from Arakawa Chemical and the shell material was purchased from Shin-Etsu Chemical.

[0058] The amine crosslinking agent was adipic acid dihydrazide, purchased from Aldrich;

[0059] The filler is talc powder, 1250 mesh;

[0060] The silane coupling agent is γ-aminopropyltriethoxysilane;

[0061] In this embodiment, 100g of low-odor, moisture-resistant foamed reinforcing film was prepared.

[0062] The amounts of the substances used are shown in Table 1.

[0063] Table 1: Amount of each substance

[0064]

[0065] Detailed preparation process:

[0066] Step 1: Preparation of epoxy resin modified product

[0067] Pre-reaction: In a 1000mL four-necked flask equipped with a stirrer, thermometer, nitrogen inlet and reflux condenser, add 65g of fluorinated polyether polyol and 65g of isophorone diisocyanate in sequence.

[0068] Temperature-controlled reaction: Nitrogen gas is introduced for protection, stirring is started, and the temperature is slowly increased to 75±2℃ and maintained at this temperature for 2.5 hours. During this period, the content of -NCO groups in the system is monitored by di-n-butylamine titration. When the deviation between the measured value and the theoretical value is less than 0.5%, the reaction is considered to be complete, and FPU prepolymer, i.e. fluorinated polyurethane prepolymer, is obtained.

[0069] Grafting reaction: In another reactor, 65g of epoxy resin E-51 was preheated to 60±5℃ to melt it and reduce its viscosity. Under stirring, the FPU (fluorinated polyurethane) prepolymer obtained in the first step was slowly added dropwise to the epoxy resin. After the addition was completed, 0.5g of catalyst dibutyltin dilaurate was added.

[0070] Insulation and endpoint determination: Maintain the temperature of the reaction system at 85±2℃ and continue the reaction for 3.5 hours to obtain the epoxy resin modified product. Discharge the product and seal it for later use.

[0071] Step 2: Preparation of rubber masterbatch

[0072] Internal mixing: Using a Benbury internal mixer, first preheat the mixing chamber temperature to 80°C, then add 60g of butadiene rubber and 40g of styrene-butadiene rubber in sequence;

[0073] Mixing: Mix at 80℃ and a rotor speed of 50 rpm for 20 minutes until the two rubbers are fully mixed and uniform to form a homogeneous blend.

[0074] Sheeting: The mixed rubber compound is transferred to a two-roll mill and passed through it three times at a roller temperature of 70°C. The sheet thickness is about 3mm. After cooling, it is cut into small pieces to obtain rubber masterbatch.

[0075] Step 3: Packing Pretreatment

[0076] Preparation of treatment solution: Mix 1.8g of silane coupling agent KH-550 with 18g of anhydrous ethanol evenly to prepare a 10% silane solution;

[0077] Surface treatment: Place 60g of talc powder in a high-speed mixer, and while stirring, use a spraying device to evenly spray the above silane solution onto the surface of the talc powder.

[0078] Drying: After spraying, continue stirring for 10 minutes, then place the treated talc powder in an oven at 100°C for 2 hours to completely remove ethanol and allow the silane to complete the coupling reaction, thus obtaining silane-treated talc powder.

[0079] Step 4: Mixing

[0080] Feeding: Using a U-shaped high-efficiency mixer with a heating jacket and S-shaped blades, add the raw materials in the following order: rubber masterbatch: 100g, epoxy resin modifier: 65g, adipic acid dihydrazide: 10g, 2-phenylimidazolium: 1.25g, 4,4'-oxobis(benzene)sulfonyl hydrazide (OBSH): 5.5g, Janus core-shell structure tackifying resin: 10g, and silane-treated talc powder: 60g;

[0081] Mixing process: Turn off the mixer, set the jacket temperature to 50±5℃, stir at 100rpm for 5 minutes to initially mix the materials, then switch to 300rpm and stir for 25 minutes until the materials are evenly mixed and form a mixed rubber compound with uniform color and no visible dry powder particles;

[0082] Step 5: Shaping and Cutting

[0083] Calendering: The mixed rubber compound is transferred to a three-roll calender. The temperatures of the upper, middle, and lower rolls are set to 90℃, 85℃, and 80℃, respectively, and the roll gap is adjusted to 1.5mm. The rubber compound is fed into the roll gap and calendered into a sheet of uniform thickness.

[0084] Composite reinforced substrate: After the sheet is drawn out from the calender, a layer of 0.18mm thick glass fiber cloth is immediately laminated on the upper and lower surfaces, and then pressed by a set of cooling rollers to firmly bond the sheet and the glass fiber cloth.

[0085] Cutting and Packaging: Guide the laminated continuous sheet to the cutting machine and cut it into the set specifications. Seal the finished sheet with polyethylene film, pack it into a carton, and store it in a cool, dry place.

[0086] Experiment Example 1: Comparison Test of Odor and Moisture Resistance

[0087] 1. Experimental objective: To verify the advantages of the film of the present invention in terms of low odor and moisture resistance compared with traditional reinforcing films.

[0088] 2. Sample Preparation

[0089] Sample of Example 1: Prepared according to the method of Example 1 above.

[0090] Comparative Example 1 Sample: A common foamed reinforcing film formulation on the market, based on ordinary epoxy resin and physically blended rubber, which is also prepared using conventional physical mixing and hot pressing methods.

[0091] 3. Experimental Methods

[0092] 3.1 Odor Test

[0093] Cut the sample into 10cm×10cm sheets, place them in a 1L sealed glass jar, and put them in an 80℃ oven for 2 hours;

[0094] Immediately after being extracted, the odor level was assessed by five trained olfactory evaluators.

[0095] Level 1: Odorless;

[0096] Level 2: Very low odor; a slight odor can only be detected by getting close to the sample, but it is not irritating.

[0097] Level 3: Low odor, a certain odor can be clearly smelled but there is still no irritation;

[0098] Level 4: Distinct odor, easily identifiable and with a slight irritant sensation;

[0099] Level 5: Severe odor, strong, pungent smell, and noticeable discomfort.

[0100] Level 6: Strong odor, extremely strong and pungent smell, causing severe discomfort;

[0101] 3.2 Moisture Resistance Test

[0102] The sample was placed in an 85℃ / 85%RH environment for 168 hours;

[0103] Test its peel strength immediately after removal;

[0104] Experimental Example 2: Foaming Uniformity and High-Temperature Stability Test

[0105] 1. Experimental objective: To verify the foaming behavior, dimensional stability and mechanical property retention of the film of the present invention at high temperatures.

[0106] 2. Sample preparation: Same as in Experiment 1.

[0107] 3. Experimental Methods

[0108] 3.1 Foaming uniformity

[0109] The sample was placed in a 150℃ oven for 20 minutes to foam. After cooling, it was sliced ​​to observe the cell structure and the foaming ratio (height after baking / height before baking) was calculated.

[0110] 3.2 Dimensional change rate at high temperature

[0111] The initial size of the sample after foaming was measured, and then it was placed at 150℃ for 1 hour. After cooling, the dimensional change rate was measured.

[0112] 3.3 Reinforcement Ratio

[0113] The sample was bonded to a steel plate, baked at 150℃ for 20 minutes, cooled for 24 hours, and the reinforcement ratio at three points of bending was tested. The final test results are shown in Table 2 below:

[0114] Table 2 Test Results

[0115]

[0116] The experimental results show that the low-odor, moisture-resistant foamed reinforcing film prepared in Example 1 of this invention is significantly superior to Comparative Example 1 in terms of odor, moisture resistance, and high-temperature stability. This verifies the comprehensive advantages of the low-odor, moisture-resistant foamed reinforcing film of this invention in terms of environmental performance, damp-heat reliability, and thermal stability. Its core lies in the synergistic effect of the Janus core-shell structure tackifying resin and the EP-FPU block copolymer, successfully achieving a balance between low odor, strong interfacial bonding, and long-term moisture resistance. This provides a high-performance, environmentally friendly structural reinforcement solution for the automotive, construction, and electronic packaging industries.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A low-odor moisture-resistant foamed patching tape, characterized by, The foaming reinforcing adhesive sheet comprises the following raw materials in mass fraction: epoxy resin modifier 50-80 parts; rubber masterbatch 80-120 parts; Janus core-shell structure tackifying resin 5-15 parts; foaming agent 3-8 parts; curing accelerator 0.5-2 parts; amine crosslinking agent 5-15 parts; filler 40-80 parts; The epoxy resin modifier is a block graft copolymer obtained by reacting fluorine-containing polyether polyol with isocyanate to obtain isocyanate-terminated prepolymer, and then reacting with the secondary hydroxyl group of the molecular chain of epoxy resin. The Janus core-shell structure tackifying resin is composed of a lipophilic core and a hydrophobic shell, the lipophilic core is hydrogenated petroleum resin or polyolefin oligomer, and the hydrophobic shell is reactive silicone or fluorine-containing oligomer. The filler is talc powder or wollastonite powder treated with silane coupling agent.

2. The foamed reinforcing sheet according to claim 1, wherein The epoxy resin is bisphenol A type epoxy resin E-51 or epoxy resin E-128.

3. The foamed reinforcing sheet according to claim 1, wherein The molecular weight of the fluorine-containing polyether polyol is 500-2000, and the isocyanate is isophorone diisocyanate.

4. The foamed reinforcing sheet according to claim 1, wherein The rubber masterbatch is obtained by mixing butadiene rubber and styrene-butadiene rubber at a mass ratio of (1:1)-(2:1).

5. The foamed reinforcing sheet according to claim 1, wherein The foaming agent is 4,4'-oxybisbenzenesulfonyl hydrazide.

6. The foamed reinforcing sheet according to claim 1, wherein The curing accelerator is 2-phenylimidazole.

7. The foamed reinforcing sheet according to claim 1, wherein The amine crosslinking agent is adipic acid dihydrazide.

8. A process for preparing the low-odor moisture-resistant foamed patch of any one of claims 1 to 7, characterized in that, The method comprises the following steps: Preparation of epoxy resin modifier and rubber masterbatch respectively; Rubber masterbatch, epoxy resin modifier, foaming agent, curing accelerator, amine crosslinking agent, Janus core-shell structure tackifying resin and filler are added in sequence, and mixed uniformly to obtain a mixture; The obtained mixture is extruded or calendered into a 1.0-2.0 mm thick sheet, covered with glass cloth and cut to obtain a low odor wet type foaming reinforcing adhesive sheet.

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