Preparation method of marine cellular board

Abstract

The invention relates to a preparation method of a marine cellular board, and belongs to the technical field of board processing. The problems that an existing plate is insufficient in moisture resistance, poor in sound insulation and heat insulation effect, prone to debonding between layers and the like in the damp and large-temperature-difference home environment are solved. According to the preparation method, cooperation of moisture prevention and light weight is achieved through the design of a gradient structure composite core material, low-viscosity resin and gradient air pressure are adopted to assist impregnation to promote filling uniformity, ultrasonic vibration is applied to an interface area, a bonding enhancer is injected to reinforce interlayer bonding, and the curing effect is optimized through a staged heating and pressurizing process. The marine cellular board prepared by the method has excellent moisture resistance, high sound insulation and heat insulation performance and stable mechanical strength, and is suitable for the household and building decoration fields of kitchen and bathroom cabinets, indoor partition walls, ceilings, door and window core materials, customized furniture and the like.

Description

Technical Field

[0001] This invention relates to the field of sheet metal processing technology, and specifically to a method for preparing marine honeycomb panels. Background Technology

[0002] Marine honeycomb panels, due to their lightweight and high specific strength, are widely used in the shipbuilding and marine engineering fields, and are gradually showing application potential in civilian fields such as home decoration, custom furniture, and interior partitions. The home environment places multi-dimensional demands on the performance of these panels: excellent moisture resistance and deformation resistance are required in high-humidity areas such as kitchens and bathrooms; good sound and heat insulation performance is needed in spaces such as bedrooms and studies to improve comfort; and as furniture or decorative materials, they also need stable structural strength and a long service life.

[0003] However, when traditional marine honeycomb panels are directly transplanted or simply modified for use in the home furnishing field, their performance often fails to meet the aforementioned comprehensive requirements. Existing manufacturing technologies mainly have the following limitations: First, in terms of core material structure design, existing technologies mostly use single-material or simple composite honeycomb core materials. To achieve lightweighting, high-porosity core materials are often used, but this leads to the board being prone to moisture absorption and having poor moisture resistance. If low-porosity dense core materials or overall hydrophobic treatment are used to improve moisture resistance, the weight will increase significantly, and may also affect sound and heat insulation performance. Existing solutions struggle to achieve a gradient and synergistic distribution of moisture resistance, lightweighting, mechanical support, and acoustic and thermal properties within the core material, resulting in boards with limited performance and an inability to simultaneously meet the complex needs of home environments.

[0004] Secondly, in resin impregnation and filling processes, existing methods mostly employ conventional vacuum impregnation or pressure impregnation. When dealing with core materials with complex structures or gradient pores, the resin liquid struggles to achieve uniform and sufficient penetration due to its own fluidity, tending to accumulate in low-porosity areas while being insufficiently filled in high-porosity areas. This uneven impregnation problem leads to inconsistent density distribution within the cured board, creating stress concentration points and severely affecting its overall mechanical stability, dimensional accuracy, and the uniformity of its sound and heat insulation performance.

[0005] Third, in terms of interface bonding, existing technologies typically rely on physical bonding between the core material and the panel, or between different core layers, supplemented by ordinary adhesives or coupling agents. This passive bonding method is acceptable under dry and constant temperature conditions, but under the long-term alternation of humidity and heat and the cycle of hot and cold in the home environment, stress is easily generated at the interface due to the difference in the coefficient of thermal expansion of the materials and moisture erosion, leading to the weakening of interlayer adhesion or even debonding, which seriously affects the durability and structural safety of the board.

[0006] Fourth, in terms of curing and molding processes, traditional methods often employ a constant temperature and pressure curing mode. This process fails to consider the differences in curing shrinkage of the resin within the gradient composite structure and the thermal expansion matching between the core material and the panel, making it highly susceptible to generating excessive internal stress within the board. The release of this internal stress can lead to warping, deformation, or microcracks in the finished board, affecting not only its appearance and flatness but also creating potential structural failures and reducing product reliability.

[0007] In summary, existing technologies for preparing boards suffer from a series of problems, including difficulty in simultaneously achieving moisture resistance and lightweighting, uneven resin filling, unreliable interfacial bonding, and high internal stress during curing. These issues prevent the boards from meeting the stringent requirements of high-end home furnishing applications for long-term stability, comfort, and safety. Therefore, an innovative preparation method is urgently needed to systematically solve these interconnected technical challenges. Summary of the Invention

[0008] One object of the present invention is to address at least the aforementioned deficiencies and to provide at least the advantages that will be described later.

[0009] To achieve these objectives and other advantages of the present invention, a method for preparing a marine honeycomb panel is provided, comprising the following steps: S1, using at least two sheet materials with different moisture-proof properties to prepare honeycomb core material units with different porosities and pore sizes; stacking these honeycomb core material units along their pore extension direction, wherein the core material unit with the strongest moisture-proof properties and the lowest porosity is placed as the moisture-proof functional layer on the outermost side, and the core material unit with weaker moisture-proof properties and higher porosity is placed as the intermediate transition layer and inner layer, forming a composite core material blank with a gradient structure; a thermally degradable polymer fiber network is provided at the interface between adjacent core layers; S2, drying the composite core material blank, and then immersing it in a low-viscosity modified resin impregnation liquid A containing filler, and impregnating it under vacuum, wherein the impregnation process maintains a decreasing air pressure gradient from the outside to the inside in the impregnation liquid A; S3, after impregnation and before resin gelation, applying ultrasonic vibration to the interface region between the moisture-proof functional layer and the intermediate transition layer, and injecting a resin interface agent B containing bonding reinforcing particles; S4. The functional gradient composite core material treated in S3 is assembled with the panel that has undergone surface treatment and is pre-coated with a decorative surface layer, and then cured using a staged heating and pressurization process.

[0010] Preferably, in the method for preparing the marine honeycomb panel of the present invention, in step S1, the degradation temperature of the thermally degradable polymer fiber web is set to be consistent with the gelation transition temperature of the impregnating resin system corresponding to the staged heating and pressurization process in step S4; the gelation transition temperature is the extrapolated starting temperature Te determined by differential scanning calorimetry, and the degradation temperature is within the range of Te ± 10°C; furthermore, the surface of the thermally degradable polymer fiber web contains at least one of epoxy groups, amino groups, or anhydride groups that can chemically react with the cured system of the modified resin.

[0011] Preferably, in the preparation method of the marine honeycomb panel of the present invention, in step S1: the moisture-proof functional layer is a honeycomb core material unit made of moisture-proof modified aramid paper or moisture-proof modified glass fiber cloth, and its porosity is controlled at 30% to 50%; the intermediate transition layer is a honeycomb core material unit made of aluminum foil or ordinary paper-based material, and its porosity is controlled at 50% to 70%; the inner layer is a honeycomb core material unit made of aluminum foil or high-porosity paper-based material, and its porosity is controlled at 70% to 85%; wherein, the honeycomb cell size of each layer of honeycomb core material unit gradually increases from the moisture-proof functional layer to the inner layer, with the cell size of the moisture-proof functional layer being 2mm to 5mm, the cell size of the intermediate transition layer being 5mm to 10mm, and the cell size of the inner layer being 10mm to 15mm.

[0012] Preferably, the modified resin impregnation solution A comprises the following components by weight: 100 parts of epoxy resin or polyurethane resin, 10 to 25 parts of reactive diluent, 5 to 15 parts of latent curing agent, and 3 to 10 parts of filler; the filler is selected from nanoporous thermal insulation materials, hollow sound-insulating microspheres, or combinations thereof; impregnation is carried out in an environment with a vacuum degree of -0.08 MPa to -0.095 MPa, and is maintained at this vacuum degree for 20 to 30 minutes.

[0013] Preferably, the thermodegradable polymer fiber web contains nanocapsules encapsulated within its fibers, which rupture in response to local pH changes caused by resin curing reactions. The nanocapsules contain a pH adjuster. The nanocapsules have a particle size of 500 nm to 2000 nm and a rupture pH range of 7.5 to 9.0. The polymer fiber web has a wettability gradient in the thickness direction, specifically: the polymer fiber web is composed of at least two types of polymer fibers with different intrinsic surface energies interwoven, with low surface energy polymer fibers concentrated on the side facing the core material with stronger moisture resistance, and high surface energy polymer fibers concentrated on the side facing the core material with weaker moisture resistance.

[0014] Preferably, while stacking the honeycomb core material units, an electrospinning device is used to directly spin and deposit the polymer solution onto the surface of the core material to be in contact, forming a fiber web; the thickness of the fiber web is 50 µm to 200 µm, and the areal density is 10 g / m². 2Up to 30 g / m 2 During the spinning process, the process parameters are adjusted in real time by the program control unit, including: a) dynamically adjusting the mixing ratio of at least two spinning solutions with different surface energy properties; b) dynamically adjusting at least one parameter among receiving distance, ambient humidity, or the strength and direction of the additional electric field; receiving distance 10 cm to 25 cm, ambient humidity 30% to 60%, and additional electric field strength 10 kV to 30 kV.

[0015] Preferably, in the preparation method of the marine honeycomb panel of the present invention, an oscillating airflow perpendicular to the interface direction is applied simultaneously during the electrospinning process, and the frequency of the oscillating airflow is coupled and controlled with the fiber deposition rate; in the thermally degradable polymer fiber, at least a portion is a core-shell structure fiber, the shell layer of which is a polymer that can be decomposed at the thermal degradation temperature, and the core layer of which is a viscous resin prepolymer that is compatible with both the modified resin impregnation liquid A and the resin interface agent B. The oscillating airflow is applied as follows: when depositing fibers toward the surface of the core material unit with weak moisture resistance and high porosity, an airflow oscillation with a first frequency and a first amplitude is applied; when depositing fibers toward the surface of the core material unit with the strongest moisture resistance and lowest porosity, an airflow oscillation with a second frequency and a second amplitude is applied; the first frequency is 10 Hz to 30 Hz, the first amplitude is 5 mm to 15 mm, the second frequency is 30 Hz to 60 Hz, and the second amplitude is 2 mm to 8 mm.

[0016] Preferably, in the method for preparing the marine honeycomb panel of the present invention, in step S1, when preparing the thermodegradable polymer fiber web by electrospinning, a first spinning solution supply system and a second spinning solution supply system are used; the first spinning solution supply system delivers a first polymer solution having a first coefficient of thermal expansion, and the second spinning solution supply system delivers a second polymer solution having a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion, and the difference is 5 × 10⁻⁶. -5 ℃ to 10×10 -5 / ℃; The program control unit connects to and controls the supply rates of the first spinning solution supply system and the second spinning solution supply system; The program control unit is configured to execute a preset supply rate control program, which causes the ratio between the supply rate V1 of the first polymer solution and the supply rate V2 of the second polymer solution to continuously and linearly change from an initial value of 12 to 15 to a final value of 0.05 to 0.08 within the entire predetermined time interval from the start of deposition on the surface of the core material unit with stronger moisture resistance to the end of deposition on the surface of the core material unit with weaker moisture resistance.

[0017] Preferably, in the method for preparing the marine honeycomb panel of the present invention, in step S1, when preparing the thermodegradable polymer fiber web, thermally expandable polymer microspheres are dispersed in at least one of a first polymer solution and a second polymer solution, and electrospinning is performed through a first spinning solution supply system and a second spinning solution supply system, so that the thermally expandable polymer microspheres are coated inside the formed polymer fibers; wherein, the second polymer solution contains 5% to 15% by mass of thermally expandable polymer microspheres; the first polymer solution contains 1% to 5% by mass of thermally expandable polymer microspheres; and the particle size of the thermally expandable polymer microspheres is 1 µm to 5 µm.

[0018] Preferably, in the method for preparing the marine honeycomb panel of the present invention, in step S1, the thermally expandable polymer microspheres used to prepare the first polymer fiber web have a first initial expansion temperature T1, and the thermally expandable polymer microspheres used to prepare the second polymer fiber web have a second initial expansion temperature T2, and T2 is greater than T1; the difference between T1 and T2 is between 10°C and 30°C; T1 is 5°C to 10°C higher than the first stage curing temperature in S4, and T2 is 5°C to 10°C lower than the second stage curing temperature in S4; the staged heating and pressurizing process in S4 is as follows: first, the temperature is increased to 80°C to 100°C at a rate of 2°C / min to 5°C / min, and a pressure of 0.3 MPa to 0.5 MPa is applied and held for 1 to 2 hours; then, the temperature is increased to 120°C to 140°C at a rate of 1°C / min to 3°C / min, and a pressure of 0.8 MPa to 1.0 MPa is applied and held for 2 to 3 hours; finally, the temperature is naturally cooled to room temperature and the pressure is released; in S2, the drying temperature is 70°C to 90°C, and the drying time is 2 hours. h to 4 h.

[0019] The present invention has at least the following beneficial effects: 1. This invention solves the comprehensive technical challenges of existing boards, such as the contradiction between moisture resistance and lightweighting, uneven resin filling, easy interface debonding, and high internal stress during curing, through a systematic approach that employs a gradient structure composite core material design, combined with gradient air pressure assisted impregnation, interfacial ultrasonic vibration and resin interface agent injection, and a staged curing process. It achieves synergistic optimization of the entire process from core material structure, impregnation and filling, interface strengthening to curing and molding, resulting in marine honeycomb panels that possess excellent moisture resistance, high and uniform sound and heat insulation, superior interlayer bonding strength, and extremely low residual stress, significantly improving their long-term durability and dimensional stability in harsh home environments.

[0020] 2. This invention solves the problems of incompatibility between the fiber web as a temporary support structure and the resin curing process, and the easy formation of weak interfaces, by precisely matching the degradation temperature of the thermodegradable polymer fiber web with the gelation temperature of the resin system and endowing it with surface reactive functional groups. It achieves the effect of effective support and positioning of the fiber web in the early stage of curing, simultaneous degradation at the resin gel point, and chemical bonding with the resin matrix. This eliminates stress concentration caused by physical residues and transforms the interfacial region into strong chemical cross-linking points, greatly enhancing the bonding stability between the core layers.

[0021] 3. This invention solves the problems of fuzzy design parameters and difficulty in quantifying performance in gradient structures by clearly defining the specific material selection, porosity range, and pore size gradient of the moisture-proof functional layer, intermediate transition layer, and inner layer. It achieves the effect of precisely fabricating an ideal configuration of "dense moisture-proof exterior, intermediate transition support, and loose buffer interior," ensuring that the board effectively blocks moisture intrusion on the outside while maximizing lightweighting and stress buffering internally, and guaranteeing a smooth transition and optimal distribution of overall mechanical properties.

[0022] 4. This invention solves the problems of unclear impregnation liquid performance and uneven filling caused by coarse impregnation process parameters by specifying the specific components and ratios of resin, diluent, curing agent, and functional filler in modified resin impregnation liquid A, and clarifying the optimized impregnation vacuum degree and time parameters. It achieves the effect of formulating a low-viscosity, high-permeability impregnation liquid with built-in sound and heat insulation functions. Furthermore, under a precisely controlled gradient vacuum environment, the resin is driven to fully and uniformly fill the gradient pores, ensuring the overall high density and performance uniformity of the board.

[0023] 5. This invention solves the problem of limited interfacial reinforcement performance caused by the chemical inertness of fiber webs and the mismatch in wettability with adjacent core materials, by encapsulating pH-responsive nanocapsules inside the fibers and designing a fiber web structure with a wettability gradient. It achieves intelligent response of the nanocapsules to changes in curing pH, releasing regulators to optimize the local cross-linking environment. Simultaneously, the wettability gradient guides the resin to preferentially accumulate at the interface and improves the spreading effect. Thus, a chemical and wettability synergistic mechanism is added to the physical interlocking, resulting in a significant improvement in interfacial bonding strength and resistance to damp heat aging.

[0024] 6. This invention solves the problems of poor adhesion of pre-fabricated fiber webs and abrupt and uncontrollable wettability gradient transitions by employing in-situ electrospinning technology and dynamically controlling the mixing ratio, electric field, and environmental parameters of the spinning solution. It achieves perfect conformal adhesion between the fiber web and the core material surface microstructure, and its wettability can achieve a continuous and smooth gradient transition according to the hydrophobicity of the core material. This realizes precise adaptation of the fiber web to the core material in terms of structure and performance, greatly improving the uniformity, consistency, and reliability of the interfacial bonding.

[0025] 7. This invention solves the problems of uneven fiber distribution and single-function fibers in static spinning by introducing oscillating airflow to assist spinning and using core-shell structured fibers. It achieves the goal of improving fiber deposition orientation and uniformity using oscillating airflow, and realizing the integrated function of "the shell layer providing support and degradation properties, and the core layer providing bonding and compatibility properties" through the core-shell structure. This results in a finer fiber web structure, more comprehensive functions, and a more significant and synergistic effect on interface enhancement.

[0026] 8. This invention solves the problems of abrupt changes in wettability gradient and incoordination of thermal expansion properties in bicomponent fiber webs by employing a dual spinning solution system and programming to control the continuous linear change of its supply rate ratio. It achieves a continuous and gradual change in the chemical composition, wettability, and thermal expansion coefficient of the fiber web along its thickness direction, perfectly matching the gradient hydrophobicity of the core material and effectively alleviating thermal stress caused by temperature changes. This provides a more stable and better-coordinated ideal interface layer for subsequent processes.

[0027] 9. This invention solves the problem of insufficient secondary filling capacity of the fiber network for micropores by coating the fiber with thermally expandable polymer microspheres of varying amounts during the electrospinning process. It achieves the effect of precisely secondary filling of residual micropores and interfacial gaps by utilizing the curing heat to trigger microsphere expansion on the basis of initial resin impregnation and filling. This significantly improves the ultimate density of the core material, eliminates microscopic defects, and further strengthens the moisture resistance, sound insulation, and mechanical strength of the board.

[0028] 10. This invention solves the problems of misaligned microsphere expansion timing and insufficient drying affecting curing by precisely aligning the initial expansion temperature (T1, T2) of the thermally expanding microspheres with the staged curing process temperatures (first stage, second stage) and optimizing drying process parameters. This achieves staged and orderly microsphere expansion, perfectly matching the resin curing process to maximize gap-filling effect, while ensuring the core material preform is in an ideal dry state before impregnation. This results in a highly synergistic process throughout the entire preparation chain (drying-impregnation-expansion-curing), ultimately yielding high-quality boards with a dense structure, minimal internal stress, and extremely stable performance. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0030] Example 1 A method for preparing a marine honeycomb panel, the specific steps of which are as follows: I. Raw Material Preparation 1. Core sheet materials: Aramid paper with hydrophobic contact angle ≥110° modified by hydrophobicity, ordinary aramid paper, and 3003 aluminum alloy foil with a thickness of 0.08mm are used to prepare honeycomb core material units with different hydrophobicity and porosity.

[0031] 2. Thermodegradable polymer fiber web: Polycaprolactone (PCL) fiber web with a thickness of 100 µm and an areal density of 20 g / m2.

[0032] 3. Modified epoxy resin impregnation solution A: by weight, it contains 100 parts epoxy resin, 18 parts monofunctional glycidyl ether type reactive diluent, 12 parts dicyandiamide latent curing agent and 5 parts nano aerogel. 4. Resin interface agent B: Epoxy resin base with added surface-modified silica particles with a particle size of 20 nm.

[0033] 5. Panel: 2 mm thick 6061 aluminum alloy plate, epoxy resin primer, 30 µm thick polyurethane thermoplastic shape memory resin film.

[0034] II. Preparation Steps Step 1 (S1): Three sheet materials with different hydrophobicities and porosities are selected and honeycomb core material units are prepared by stretching and shaping: core material unit prepared by hydrophobically modified aramid paper (strongest hydrophobicity), core material unit prepared by ordinary aramid paper, and core material unit prepared by 3003 aluminum alloy foil (highest porosity). The three are stacked along the direction of pore extension, with the hydrophobically modified aramid paper core material as the water-facing functional layer placed on the outermost side, the ordinary aramid paper core material as the intermediate transition layer, and the aluminum alloy foil core material as the inner layer, forming a gradient structure composite core material blank; a thermodegradable polycaprolactone fiber web is laid at the interface of adjacent core layers.

[0035] Step 2 (S2): Place the composite core material blank in a forced-air drying oven and dry at 85℃ for 3 hours to remove moisture. Prepare modified resin impregnation solution A, and stir and mix all components evenly in a 50℃ water bath, then degas under vacuum for 30 minutes. Immerse the dried core material blank in impregnation solution A in a sealed impregnation tank. Start the vacuum system to achieve and stabilize the vacuum level in the tank at -0.095MPa, and maintain a decreasing pressure gradient in the impregnation solution from the tank wall (outer side) to the core material center (inner side) through the control system. Maintain impregnation under these conditions for 25 minutes.

[0036] Step 3 (S3): After the first impregnation is completed, within 25 minutes after impregnation and before the resin gels, apply ultrasonic vibration at 28 kHz and 200 W to the interface area between the moisture-proof functional layer and the intermediate transition layer for 90 seconds; at the same time, inject resin interface agent B containing modified nano silica into the interface area through a micro dispensing system to ensure complete coverage of the interface area.

[0037] Step 4 (S4): The mating surfaces of the 6061 aluminum alloy panels are roughened by sandblasting, coated with epoxy resin primer, and then pre-coated with a thermoplastic shape memory resin film. The composite core material treated in S3 is placed between the two pre-treated panels, ensuring that the core material channels are perpendicular to the panels. After assembly, the panels are transferred to an autoclave. A staged heating and pressurization process is adopted: first, the temperature is increased to 90℃ at 3℃ / min, and a pressure of 0.4 MPa is applied and held for 1.5 hours; then, the temperature is increased to 130℃ at 2℃ / min, and a pressure of 1.0 MPa is applied and held for 3 hours; finally, the panels are allowed to cool naturally to room temperature, and the pressure is released to obtain the finished marine honeycomb panel.

[0038] Example 2 The preparation method of the marine honeycomb panel, based on Example 1, includes the following specific steps: I. New Raw Materials and Equipment 1. New raw material: epoxy group grafting agent (used for surface modification of fiber web).

[0039] 2. New equipment: Differential scanning calorimeter (DSC).

[0040] II. Key Difference Steps In the functionally graded composite core material preform preparation stage (S1), the preparation and modification of thermally degradable polymer fiber web are carried out as follows: 1. The extrapolated gelation transition onset temperature Te = 88℃ of the modified epoxy resin impregnation solution A and its curing system used in Example 1 was determined by differential scanning calorimetry. The degradation temperature of the polycaprolactone fiber web was set to 88℃ (within the range of Te ± 10℃).

[0041] 2. The surface of the polycaprolactone fiber web is modified by immersing it in an epoxy group grafting agent solution and reacting it at 60°C for 2 hours to graft epoxy groups onto the surface of the fiber web, ensuring that it can chemically react with the curing system of the modified epoxy resin.

[0042] 3. The remaining core material lamination, impregnation, interface strengthening, and preform curing steps are the same as in Example 1.

[0043] Example 3 The preparation method of the marine honeycomb panel, based on Example 1, includes the following specific steps: In the functionally graded composite core material preform preparation stage (S1), the specific preparation parameters of the core material unit are as follows: 1. Using aramid paper modified with hydrophobic fluorocarbon resin, a regular hexagonal honeycomb core material unit was prepared, with a porosity of 40% and a cell size of 3mm, to obtain a moisture-proof functional layer.

[0044] 2. Honeycomb core material units were prepared using ordinary aramid paper, with a porosity of 60% and a cell size of 8mm, to obtain an intermediate transition layer.

[0045] 3. A honeycomb core material unit was prepared using 3003 aluminum alloy foil, with a porosity of 80% and a cell size of 13mm, to obtain the inner layer.

[0046] 4. Lay the layers in the order of moisture-proof functional layer - intermediate transition layer - inner layer, and lay a thermodegradable polymer fiber web at the interface of adjacent core layers. The remaining steps are the same as in Example 1.

[0047] Example 4 The preparation method of the marine honeycomb panel, based on Example 1, includes the following specific steps: 1. Weigh 100 parts polyurethane resin, 20 parts reactive diluent, 10 parts latent curing agent and 8 parts glass microspheres (as hollow sound insulation microspheres) by weight, stir and mix evenly, and vacuum degas for 30 minutes to obtain modified polyurethane resin impregnation solution A.

[0048] 2. Adjust the single impregnation process in step two: Immerse the dried core material blank into the impregnation solution A prepared above, precisely control the vacuum degree in the sealed impregnation tank at -0.095 MPa, and maintain the air pressure gradient from the outside to the inside, and keep it impregnated for 28 minutes under these conditions.

[0049] 3. The remaining steps are the same as in Example 1.

[0050] Example 5 The preparation method of the marine honeycomb panel, based on Example 2, includes the following specific steps: I. New raw materials 1. Nanocapsules: pH adjuster capsules coated with urea-formaldehyde resin (particle size 1000 nm, rupture pH 8.0).

[0051] 2. Polymer fibers: low surface energy polytetrafluoroethylene (PTFE) fiber, high surface energy polyamide (PA) fiber.

[0052] II. Key Difference Steps Preparation of thermodegradable polymer fiber webs: 1. In the preparation of biodegradable fibers, nanocapsules are uniformly dispersed in the spinning solution, and the nanocapsules are encapsulated inside the final fiber through a process.

[0053] 2. A polymer fiber web is prepared by interweaving low surface energy PTFE fibers and high surface energy PA fibers. By controlling the process, the PTFE fibers are enriched on the side facing the moisture-proof functional layer (a core material with strong hydrophobicity), and the PA fibers are enriched on the side facing the intermediate transition layer (a core material with weak hydrophobicity), thereby forming a wettability gradient in the thickness direction of the fiber web.

[0054] 3. The degradation temperature of the fiber web is still set at 88°C, and epoxy groups are grafted onto the surface. The remaining steps are the same as in Example 2.

[0055] Example 6 The preparation method of the marine honeycomb panel, based on Example 5, includes the following specific steps: I. New equipment: Electrospinning equipment, which includes a program control unit, a supply system capable of delivering at least two different spinning solutions, and a deposition receiving device with adjustable parameters.

[0056] II. Key Difference Steps While the honeycomb core material units are stacked, in-situ spinning deposition is performed using the electrospinning equipment: 1. Weigh 1.2 g of polytetrafluoroethylene (PTFE) powder and dissolve it in 10 mL of a mixture of acetone and N,N-dimethylformamide (DMF) in a mass ratio of 7:3. Stir magnetically for 6 hours until completely dissolved. Then, add 2% of the pH-responsive nanocapsules from Example 5 by mass of the spinning solution and ultrasonically disperse for 30 minutes to obtain a homogeneous spinning solution L.

[0057] Weigh 1.5 g of polyamide (PA) particles and dissolve them in 10 mL of a mixed solvent of formic acid and acetic acid in a mass ratio of 9:1. Heat the solution in a water bath to 50°C and stir magnetically for 4 hours until completely dissolved to obtain spinning solution H.

[0058] 2. Fill two 20 mL medical syringes, respectively, with spinning solution L and spinning solution H, and attach them to a dual-injection pump. Secure the core material unit (e.g., the contact surface between the moisture-proof functional layer and the intermediate transition layer) that has been aligned with the fiber web to be laid onto the receiving platform. Preset the initial parameters in the program control unit: receiving distance 18 cm, ambient humidity 45%, applied voltage +25 kV (needle tip positive, receiving platform negative).

[0059] 3. Start the equipment, and the program control unit executes the preset dynamic mixing program. In the initial stage, set the injection pump supply rate: spinning solution L is 0.8 mL / h, spinning solution H is 0.1 mL / h, and at this time, the low surface energy components in the mixture are dominant.

[0060] As deposition proceeds, the program control unit linearly reduces the supply rate of spinning solution L from 0.8 mL / h to 0.05 mL / h within the 60-minute deposition period, while simultaneously linearly increasing the supply rate of spinning solution H from 0.1 mL / h to 0.7 mL / h. This results in a continuous wettability gradient in the thickness direction of the deposited fiber web, from the side closest to the moisture-proof functional layer to the side closest to the intermediate transition layer. Throughout the spinning process, the receiving distance, ambient humidity, and electric field strength are maintained within ±5% of their set values.

[0061] 4. Through the above process, a uniform fiber web is directly deposited at the core-material interface. By controlling the total deposition time, the final fiber web thickness is approximately 150 µm, and the areal density is approximately 25 g / m². 2 .

[0062] 5. After completing the deposition of the fiber web at this interface, proceed to the deposition of the other interface or directly proceed to the next core material stacking step. All subsequent steps, including core material preform drying, gradient air pressure assisted impregnation (S2), ultrasonic interface strengthening (S3), preform assembly and staged curing (S4), are consistent with the settings of Example 1 and the aforementioned examples.

[0063] Example 7 The preparation method of the marine honeycomb panel, based on Example 6, includes the following specific steps: I. New Raw Materials and Equipment New raw materials: Raw materials used to prepare core-shell structured fibers. The shell polymer raw material must meet the characteristic of being decomposable at a set thermal degradation temperature (e.g., 88°C); the core polymer raw material is a viscous resin prepolymer with good compatibility with both modified resin impregnation liquid A and resin interface agent B.

[0064] New equipment: Oscillating airflow generator, which can generate oscillating airflow with adjustable frequency and amplitude and direction perpendicular to the deposition interface.

[0065] II. Key Difference Steps 1. In the electrospinning process of Example 6, an oscillating airflow generator is simultaneously activated to apply an oscillating airflow perpendicular to the interface direction to the fiber deposition area. The program control unit couples the frequency of the oscillating airflow with the real-time fiber deposition rate to optimize fiber distribution.

[0066] 2. Adjust the spinning process to prepare fibers with at least a core-shell structure. Specifically, the shell layer is composed of a polymer (such as polycaprolactone) that can decompose at thermal degradation temperatures, and the core layer is composed of the aforementioned viscous resin prepolymer.

[0067] 3. Set differentiated oscillation airflow parameters: a) When depositing fibers on the surface of the core material unit facing the intermediate transition layer (weaker moisture resistance, higher porosity), apply airflow oscillation with a first frequency (20 Hz) and a first amplitude (10 mm). b) When depositing fibers on the surface of the core material unit facing the moisture-proof functional layer (strongest moisture resistance, lowest porosity), apply airflow oscillation with a second frequency (45 Hz) and a second amplitude (5 mm).

[0068] 4. The rest of the steps regarding the dynamic adjustment of spinning parameters, fiber web gradient design, and all subsequent steps are the same as in Example 6.

[0069] Example 8 The preparation method of the marine honeycomb panel, based on Example 7, includes the following specific steps: I. Key Differences Steps 1. Define the spinning solution system: When preparing the fiber web in step S1, define the use of a first spinning solution supply system and a second spinning solution supply system.

[0070] 2. Configuration of spinning solution properties: A first spinning solution supply system delivers a first polymer solution with a first coefficient of thermal expansion. A second spinning solution supply system delivers a second polymer solution with a second coefficient of thermal expansion. The first coefficient of thermal expansion is controlled to be greater than the second coefficient of thermal expansion, with the difference between the two being approximately 7 × 10⁻⁶. -5 / ℃.

[0071] 3. Programmed Supply Rate Control: The program control unit connects to and precisely controls the supply rates of the first and second spinning solution supply systems. The program control unit executes a preset supply rate control program. This program causes the ratio (V1 / V2) of the supply rate V1 of the first polymer solution to the supply rate V2 of the second polymer solution to continuously and linearly change from a high initial value of 13 to an extremely low final value of 0.07 throughout the entire predetermined time interval from the start of deposition on the surface of the more moisture-resistant core material unit to the end of deposition on the surface of the less moisture-resistant core material unit.

[0072] 4. The remaining parameters regarding the oscillating gas flow, core-shell fiber preparation, and all subsequent process steps are the same as in Example 7.

[0073] Example 9 The preparation method of the marine honeycomb panel, based on Example 8, includes the following specific steps: I. New raw materials Thermally expandable polymer microspheres (particle size 3 µm).

[0074] II. Key Difference Steps 1. In step S1, when preparing the thermodegradable polymer fiber web, the thermally expandable polymer microspheres are dispersed in a first polymer solution and a second polymer solution.

[0075] 2. Controlling the amount of microspheres added: In the second polymer solution (used to form a specific portion of the fiber web), the mass fraction of the thermally expandable polymer microspheres added is 10%. In the first polymer solution (used to form another portion of the fiber web), the mass fraction of the thermally expandable polymer microspheres added is 3%.

[0076] 3. Electrospinning is performed through a first spinning solution supply system and a second spinning solution supply system, so that thermally expandable polymer microspheres are coated inside the formed polymer fiber (including core-shell structure).

[0077] 4. The remaining parameters regarding the control of the double spinning solution supply rate, the oscillating airflow-assisted spinning, and all subsequent steps are the same as in Example 8.

[0078] Example 10 The preparation method of the marine honeycomb panel, based on Example 9, includes the following specific steps: I. Key Differences Steps 1. Selection of characteristic microspheres: Thermally expandable polymer microspheres for preparing the first polymer fiber web, having a first initial expansion temperature T1, T1 = 95℃. Thermally expandable polymer microspheres for preparing the second polymer fiber web, having a second initial expansion temperature T2, T2 = 120℃.

[0079] 2. Set the drying temperature of the composite core material blank to 90℃ and the drying time to 3 hours.

[0080] 3. A staged heating and pressurization process is adopted: Stage 1: Heat to 90℃ at a rate of 3℃ / min, apply 0.4 MPa pressure, and hold for 1.5 h. Stage 2: Heat to 130℃ at a rate of 2℃ / min, apply 1.0 MPa pressure, and hold for 3 h. Finally, allow to cool naturally to room temperature and release the pressure.

[0081] 4. All parameters for the remaining steps, such as spinning, impregnation, and interface strengthening, are the same as in Example 9.

[0082] Experiment and Analysis I. Experimental Design Sample preparation: A total of 11 sets of samples were prepared in this experiment, including 10 sets of example samples (Examples 1-10) and 1 set of comparative sample (Comparative Example 1). All samples were uniformly sized at 500mm×500mm×20mm. The preparation process strictly followed the corresponding technical solution and gradually added optimized features.

[0083] Comparative Example 1 employed conventional preparation methods, including a single ordinary aramid paper honeycomb core material (porosity 60%, pore size 8 mm), ordinary vacuum impregnation (without gradient magnetic field), interface coating with coupling agent, and single temperature and pressure curing (120℃, 0.8 MPa, 3 h). Examples 1-10 were prepared using the methods described in Examples 1-10, respectively.

[0084] II. Testing Methods 1. Water absorption rate test According to GB / T 1733-1993 "Determination of Water Resistance of Paint Film", the sample was cut into 100mm×100mm×20mm specimens, dried to constant weight (mass m0), and then completely immersed in 3.5wt% sodium chloride solution (simulated seawater). After 72 hours, the specimens were removed, the surface moisture was wiped off, and the mass m1 was measured. The water absorption rate was calculated using the formula: Water absorption rate (%) = (m1 - m0) / m0 × 100%. Three parallel specimens were tested in each group, and the average value was taken.

[0085] 2. Interlaminar shear strength test According to GB / T 1450.1-2005 "Test Method for Interlaminar Shear Strength of Fiber Reinforced Plastics", 100mm×25mm×20mm specimens were prepared. A universal testing machine was used to conduct short beam shear tests at a loading rate of 2mm / min. The failure load F was recorded. The interlaminar shear strength was calculated using the formula: τ = 3F / 2bh (where b is the specimen width and h is the specimen thickness). Five parallel specimens were tested in each group, and the average value was taken.

[0086] 3. Bending strength test According to GB / T 9341-2008 "Determination of Flexural Properties of Plastics", 80mm×10mm×20mm specimens were prepared. A universal testing machine was used with a support spacing of 64mm and a loading rate of 2mm / min. The maximum bending load was recorded, and the bending strength was calculated. Five parallel specimens were tested in each group, and the average value was taken.

[0087] 4. Salt spray aging stability test According to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", a neutral salt spray aging test (5% sodium chloride solution, temperature 35℃, continuous spray) was conducted. After aging for 720 hours, the water absorption rate, interlaminar shear strength, and flexural strength of the samples were tested, and the performance retention rate was calculated as (performance after aging / performance before aging × 100%). Three parallel samples were tested in each group, and the average value was taken.

[0088] III. Experimental Data The performance test data of each group of samples are shown in Table 1. The data in the table are the "mean ± standard deviation" of three or more parallel tests. The water absorption retention rate reflects the increase in water absorption after aging (the smaller the value, the better), and the interlaminar shear strength / flexural strength retention rate reflects the performance degradation (the larger the value, the better).

[0089] Table 1: Performance test data of each group of samples IV. Data Analysis 1. Comparative Example 1 has the worst performance in all aspects, with a water absorption rate of 3.48%, an interlaminar shear strength of 21.3 MPa, a flexural strength of 325 MPa, and a low performance retention rate after salt spray aging (interlaminar shear strength retention rate of 68.5% and flexural strength retention rate of 72.3%), which cannot meet the long-term use requirements of marine environment.

[0090] 2. Compared with Comparative Example 1, Example 1 showed a water absorption rate of 1.25%, an interlaminar shear strength increase of 34.3%, a flexural strength increase of 22.5%, and a significant improvement in salt spray aging performance retention, achieving a fundamental improvement in water resistance, mechanical properties, and stability.

[0091] 3. Compared with Example 1, Example 2 showed a 18.4% reduction in water absorption, a 13.3% increase in interlaminar shear strength, a 7.0% increase in flexural strength, enhanced interfacial stability after salt spray aging, and an interlaminar shear strength retention rate of 87.3%.

[0092] 4. Compared with Example 2, Example 3 has a 7.8% lower water absorption rate, a 4.0% higher interlaminar shear strength, a 2.8% higher flexural strength, optimized core material mechanical compatibility, and more balanced overall performance.

[0093] 5. Compared with Example 3, Example 4 has a 17.9% lower water absorption rate, a 7.4% higher interlaminar shear strength, a 6.2% higher flexural strength, increased core material density, and further enhanced water resistance and mechanical properties.

[0094] 6. Compared with Example 4, Example 5 showed a 33.3% reduction in water absorption, a 14.6% increase in interlaminar shear strength, a 10.1% increase in flexural strength, significantly enhanced corrosion and peel resistance, and a 95.7% salt spray aging retention rate.

[0095] 7. Compared with Example 5, Example 6 has a 13.5% lower water absorption rate, a 5.5% higher interlaminar shear strength, a 4.7% higher flexural strength, improved interfacial bonding uniformity, and further optimized performance stability.

[0096] 8. Compared with Example 6, Example 7 has a 15.6% lower water absorption rate, a 5.5% higher interlaminar shear strength, a 5.0% higher flexural strength, a more uniform fiber distribution, and a more significant interface reinforcement effect.

[0097] 9. Compared with Example 7, Example 8 has a 15.8% lower water absorption rate, a 5.4% higher interlaminar shear strength, a 4.6% higher flexural strength, a smoother wettability gradient transition, and better core material structure coordination.

[0098] 10. Compared with Example 8, Example 9 has a 21.9% lower water absorption rate, a 5.3% higher interlaminar shear strength, a 4.4% higher flexural strength, more complete core material pore filling, and further improved water resistance and mechanical properties.

[0099] 11. Among all samples, Example 10 showed the best performance, with a water absorption rate of only 0.18%, an interlaminar shear strength of 54.6 MPa, a flexural strength of 642 MPa, and a performance retention rate of over 99% after salt spray aging. Its water resistance, interfacial strength, mechanical properties, and long-term stability met the standards for high-end marine engineering applications.

[0100] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Further modifications can be readily implemented by those skilled in the art.

Claims

1. A method of making a marine honeycomb panel, characterized by, The method comprises the following steps: S1. Using at least two sheet materials with different moisture resistance to prepare honeycomb core material units with different porosities and pore sizes; stacking the honeycomb core material units along the direction of their pore extension, wherein the core material unit with the strongest moisture resistance and the lowest porosity is placed as the moisture-proof functional layer on the outermost side, the core material unit with weaker moisture resistance and higher porosity is placed as the intermediate transition layer and the inner layer, and a composite core material blank with a gradient structure is formed; a network of heat-degradable polymer fibers is arranged on the interface between adjacent core layers; S2. Drying the composite core material blank, then immersing it in a low-viscosity modified resin impregnating solution A containing fillers, and performing impregnation in a vacuum environment; the impregnation process maintains a decreasing air pressure gradient from the outside to the inside in the impregnating solution A; S3. After impregnation and before resin gelation, ultrasonic vibration is applied to the interface area between the moisture-proof functional layer and the intermediate transition layer, and a resin interfacial agent B containing adhesion-enhancing particles is injected; S4. The functional gradient composite core material after S3 treatment is combined with a panel that has been surface-treated and pre-coated with a decorative surface layer, and a staged temperature and pressure curing process is used for curing.

2. The method for preparing a marine honeycomb panel as described in claim 1, characterized in that, In step S1, the degradation temperature of the network of heat-degradable polymer fibers is set to be consistent with the gelation transition temperature point of the impregnated resin system corresponding to the staged temperature and pressure curing process in step S4; the gelation transition temperature point is the extrapolated onset temperature Te measured by differential scanning calorimetry, and the degradation temperature is within the range of Te±10℃; Moreover, the surface of the network of heat-degradable polymer fibers contains at least one of an epoxy group, an amino group, or an anhydride group that can chemically react with the curing system of the modified resin.

3. The method for preparing a marine honeycomb panel as described in claim 1, characterized in that, In step S1: The moisture-proof functional layer is a honeycomb core material unit made of moisture-proof modified aramid paper or moisture-proof modified glass fiber cloth, with a porosity controlled at 30% to 50%; The intermediate transition layer is a honeycomb core material unit made of aluminum foil or ordinary paper-based material, with a porosity controlled at 50% to 70%; The inner layer is a honeycomb core material unit made of aluminum foil or high-porosity paper-based material, with a porosity controlled at 70% to 85%; Wherein, the cell size of each layer of honeycomb core material unit increases gradually from the moisture-proof functional layer to the inner layer, the cell size of the moisture-proof functional layer is 2 mm to 5 mm, the cell size of the intermediate transition layer is 5 mm to 10 mm, and the cell size of the inner layer is 10 mm to 15 mm.

4. The method for preparing a marine honeycomb panel as described in claim 1, characterized in that, The modified resin impregnating solution A contains the following components by mass fraction: 100 parts of epoxy resin or polyurethane resin, 10 to 25 parts of active diluent, 5 to 15 parts of latent curing agent, and 3 to 10 parts of filler; the filler is selected from nano-porous thermal insulation material, hollow sound insulation microspheres, or a combination thereof; The impregnation is carried out in an environment with a vacuum degree of -0.08 MPa to -0.095 MPa, and is maintained at this vacuum degree for 20 to 30 minutes.

5. The method for preparing the marine honeycomb panel according to claim 2, characterized in that, The fibers of the thermally degradable polymer fiber web are encapsulated with nanocapsules that can be ruptured in response to local pH value changes caused by resin curing reaction, and the nanocapsules contain a pH adjuster; the particle size of the nanocapsules is 500 nm to 2000 nm, and the rupture pH value range is 7.5 to 9.0; The polymer fiber web has a wettability gradient in the thickness direction, specifically: the polymer fiber web is composed of at least two types of polymer fibers with different intrinsic surface energies, and the low-surface-energy polymer fibers are enriched on the side facing the core material with stronger moisture resistance, and the high-surface-energy polymer fibers are enriched on the side facing the core material with weaker moisture resistance.

6. The method for preparing a marine honeycomb panel as described in claim 5, characterized in that, In the meantime of stacking the honeycomb core material units, the polymer solution is directly spun and deposited on the surface of the core material to be contacted by using the electrospinning equipment to form a fiber web; the thickness of the fiber web is 50 µm to 200 µm, and the area density is 10 g / m 2 to 30 g / m 2 ; During the spinning process, the process parameters are adjusted in real time by a program control unit, including: a) dynamically adjusting the mixing ratio of at least two different surface energy characteristic spinning solutions; b) dynamically adjusting at least one of the receiving distance, the ambient humidity, or the additional electric field strength and direction; the receiving distance is 10 cm to 25 cm, the ambient humidity is 30% to 60%, and the additional electric field strength is 10 kV to 30 kV.

7. The method for preparing a marine honeycomb panel as described in claim 6, characterized in that, An oscillating gas flow perpendicular to the interface direction is applied synchronously during the electrospinning process, and the frequency of the oscillating gas flow is coupled with the fiber deposition rate for control; In the thermally degradable polymer fiber, at least a part is a core-shell structure fiber, the shell layer is a polymer that can be decomposed at the thermal degradation temperature, and the core layer is a viscous resin prepolymer that is compatible with both the modified resin impregnating liquid A and the resin interface agent B; The application mode of the oscillating gas flow is: when depositing fibers on the surface of the core material unit with weaker moisture resistance and higher porosity, a gas flow oscillation with a first frequency and a first amplitude is applied; when depositing fibers on the surface of the core material unit with the strongest moisture resistance and the lowest porosity, a gas flow oscillation with a second frequency and a second amplitude is applied; the first frequency is 10 Hz to 30 Hz, the first amplitude is 5 mm to 15 mm, the second frequency is 30 Hz to 60 Hz, and the second amplitude is 2 mm to 8 mm.

8. The method for preparing a marine honeycomb panel as described in claim 7, characterized in that, In step S1, when preparing the thermally degradable polymer fiber web by the electrospinning method, a first spinning solution supply system and a second spinning solution supply system are used; The first dope supply system delivers a first polymer solution having a first coefficient of thermal expansion, the second dope supply system delivers a second polymer solution having a second coefficient of thermal expansion, and the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion by a difference of 5 x 10 -5 °C to 10 x 10 -5 / °C. The program control unit connects and controls the supply rates of the first spinning solution supply system and the second spinning solution supply system; The program control unit is configured to execute a preset supply rate control program, which causes the ratio between the supply rate V1 of the first polymer solution and the supply rate V2 of the second polymer solution to continuously linearly change from an initial value of 12 to 15 to a terminal value of 0.05 to 0.08 within a predetermined time interval from the beginning of deposition on the surface of the core material unit with stronger moisture resistance to the end of deposition on the surface of the core material unit with weaker moisture resistance.

9. The method for preparing a marine honeycomb panel as described in claim 8, characterized in that, In step S1, when preparing the thermally degradable polymer fiber web, the thermally expandable polymer microspheres are dispersed in at least one of the first polymer solution and the second polymer solution, and the electrospinning is performed by the first spinning solution supply system and the second spinning solution supply system, so that the thermally expandable polymer microspheres are coated inside the formed polymer fibers; The second polymer solution contains 5% to 15% of the thermally expandable polymer microspheres by mass fraction; the first polymer solution contains 1% to 5% of the thermally expandable polymer microspheres by mass fraction; and the thermally expandable polymer microspheres have a particle size of 1 µm to 5 µm.

10. The method for preparing a marine honeycomb panel as described in claim 9, characterized in that, In step S1, the thermally expandable polymer microspheres for preparing the first polymer fiber web have a first initial expansion temperature T1, and the thermally expandable polymer microspheres for preparing the second polymer fiber web have a second initial expansion temperature T2, and T2 is greater than T1; The difference between T1 and T2 is between 10℃ and 30℃; T1 is 5℃ to 10℃ higher than the first-stage curing temperature in S4, and T2 is 5℃ to 10℃ lower than the second-stage curing temperature in S4; The stepwise temperature and pressure process in S4 is: first, temperature is raised to 80℃ to 100℃ at a rate of 2℃ / min to 5℃ / min, and then pressure is applied at 0.3MPa to 0.5 MPa for 1 h to 2 h; then, temperature is raised to 120℃ to 140℃ at a rate of 1℃ / min to 3℃ / min, and then pressure is applied at 0.8 MPa to 1.0 MPa for 2 h to 3 h; finally, natural cooling is performed to room temperature, and then pressure is released; the drying temperature in S2 is 70℃ to 90℃, and the drying time is 2 h to 4 h.

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