Large-size arc-shaped decorative door plate and preparation method thereof

Abstract

The invention discloses a large-size arc-shaped decorative door plate which is composed of a face plate, a core plate, a bottom plate and a facing layer. The face plate and the bottom plate are high-toughness fiber plates with three-dimensional porous structures, the core plate is plywood, and the facing layer is a single-facing ultrathin high-density fiber plate. By means of the three-section pressurization and the high-frequency hot bending process capable of being monitored and adjusted in real time, the advantages of the face plate, the core plate and the bottom plate are combined, and integrated forming is achieved. The process is more uniform in pressure and temperature, more stable in structure and more accurate in size control, meanwhile, the internal stress distribution of the plate is more balanced, the deformation and cracking risks are remarkably reduced, splicing gaps are reduced, and deformation of the arc-shaped plate is effectively resisted. The large-size arc-shaped decorative door plate is large in breadth size, high in decorativeness, high in size precision, excellent in structural stability and environmental protection performance, free of raised grains, springback, layering and cracking and capable of meeting the quality requirement of the high-end customized home furnishing market for the large-size arc-shaped decorative door plate.

Description

Technical Field

[0001] This invention belongs to the field of decorative panel technology, specifically relating to a large-size curved decorative door panel and its preparation method. Background Technology

[0002] In the high-end custom home furnishing sector, the integrated curved design of "doors, walls, and cabinets" has become a new trend leading consumer growth. The demand for larger curved decorative door panels is increasing, with a market supply exceeding 2400×440mm. Curved products not only offer a more sophisticated appearance and enhance spatial security, but also achieve a high degree of stylistic unity and maximized functionality, significantly increasing product added value. Despite strong market demand, traditional processes still face significant technical bottlenecks in producing large-sized curved decorative door panels, including high costs, low efficiency, large dimensional deviations, a tendency for surface wavy patterns, and issues such as springback deformation and delamination / cracking. The manufacturing of large-sized curved decorative door panels is a recognized technical challenge within the industry.

[0003] Currently, the mainstream manufacturing processes for curved decorative door panels can be divided into the following three types: 1. Microwave Heating Bending Forming: This method involves locally heating and softening the door panel substrate with microwaves before bending it into shape. However, it is difficult to control the uniformity of heating, which can easily lead to localized overheating or insufficient softening, resulting in uneven internal stress distribution in the finished product and a tendency for springback deformation after long-term use.

[0004] II. Multi-layer thin sheet bonding and cold pressing bending: Multi-layer glued thin sheets are placed in an arc-shaped mold and cold pressed for curing. This method has poor flexibility, the finished product surface has obvious wavy patterns, and it is prone to delamination, cracking or breakage. In addition, the curing cycle is long (usually more than 24 hours), resulting in low production efficiency.

[0005] 3. Grooving and bending process: A V-shaped groove is cut on the back of the board, and then glue is filled in to fix it after bending. This process will destroy the continuity of the substrate, resulting in a significant decrease in strength, making it difficult to process, prone to cracking, and the smoothness of the curved surface is poor. It is mostly suitable for occasions where aesthetics are not a high priority.

[0006] All three processes for producing large-size curved decorative door panels present some intractable problems. Therefore, developing a production process for large-size curved decorative door panels that can simultaneously achieve high precision, high efficiency, low cost, and stable quality is an urgent technological need and has significant application value. Summary of the Invention

[0007] The purpose of this application is to overcome the above-mentioned shortcomings of the prior art and provide a large-size curved decorative door panel to overcome the above-mentioned technical problems existing in the existing related technologies, provide a new solution for curved decorative door panels, and provide a new type of large-size curved decorative door panel for high-end customized home furnishings that is cost-effective, resistant to deformation, does not delaminate, does not crack or break, and is environmentally friendly.

[0008] Another objective of this application is to provide a method for preparing the aforementioned large-size curved decorative door panel.

[0009] To achieve the above-mentioned application objectives, this application provides a large-size curved decorative door panel, wherein the large-size curved decorative door panel is formed by molding a panel, a core board, a base board and a decorative layer in one step using a high-frequency bending press; the panel and the base board are high-toughness fiberboard with a three-dimensional porous structure, the core board is plywood, and the decorative layer is a single-sided ultra-thin high-density fiberboard. The front and back panels are made by uniformly mixing wood fiber and polyester fiber, applying formaldehyde-free adhesive and foaming agent, and then air-flow laying and hot pressing. The plywood is made of eucalyptus rotary-cut veneer as raw material and bonded with environmentally friendly adhesive. The number of layers is odd, and the fiber direction of adjacent veneer layers is perpendicular to each other. The back of the single-sided ultra-thin high-density fiberboard has a concave-convex structure and ventilation holes. The concave-convex structure consists of multiple convex structures arranged in a matrix and alternately set with concave structures in between. The ventilation holes are located above the concave-convex structure.

[0010] This invention perfectly integrates the advantages of single-sided ultra-thin high-density fiberboard, high-toughness fiberboard, and plywood. It employs a three-stage pressure application and a high-frequency hot bending process with real-time monitoring and adjustment for integrated molding. This results in more uniform pressure and temperature, a more stable structure, and more precise dimensional control. Simultaneously, it achieves a more balanced internal stress in the board, reducing the likelihood of deformation and cracking. It also minimizes splicing surfaces, preventing warping caused by changes in environmental temperature and humidity. The face and back panels are made of high-toughness fiberboard, preventing deformation. Its three-dimensional porous structure prevents breakage during bending and stretching, effectively solving the problem of cracking and deformation caused by the anisotropy of eucalyptus veneer, while also addressing the issue of waviness. The plywood features an odd-layer symmetrical structure, ensuring uniform internal stress and effectively offsetting the expansion and contraction differences caused by the anisotropy of wood. The perpendicular arrangement of fibers in adjacent veneer layers greatly enhances the dimensional stability and mechanical uniformity of the board in all directions, making it more resistant to bending and warping than solid wood. The single-sided ultra-thin high-density fiberboard features a textured surface that creates a glue-nail structure between the veneer layer and the backing board, ensuring a strong bond between them. The ventilation holes facilitate moisture release during pressing, ensuring the quality of the board surface. During softening treatment, it absorbs softening agents more easily, achieving a better softening effect and reducing deformation. At the same time, it increases adhesive penetration and improves bonding strength when applying glue.

[0011] Preferably, the panel and the base plate are of the same thickness and material, with a thickness of 1.0–2.0 mm and a density of 0.3–0.5 g / cm³. 3 Formaldehyde emission ≤0.025mg / m³ 3 The plywood has a moisture content of 6.0–16.0% and a formaldehyde emission level ≤0.050 mg / m³. 3 The panel and base plate are of the same thickness and material, and will not break when bent or stretched, thus avoiding deformation. The moisture content of the plywood is low, so it is not prone to excessive expansion, contraction, warping, or cracking due to moisture absorption or drying in the usage environment. It can adapt well to indoor environments with temperature and humidity changes (such as rooms with underfloor heating and areas with seasonal changes), ensuring the long-term stability of furniture or decoration structures.

[0012] More preferably, the plywood uses an environmentally friendly adhesive, a vinyl acetate-ethylene copolymer emulsion, which is a polymer emulsion made from vinyl acetate and ethylene monomers through an emulsion polymerization process. This adhesive is formaldehyde-free, highly flexible, has a low curing temperature, high bonding strength, and is unaffected by humidity, effectively ensuring that the layers of material can be firmly bonded without delamination after bending.

[0013] Preferably, the single-sided ultra-thin high-density fiberboard is formed by bonding decorative paper impregnated with urea-formaldehyde resin and coated with amine-formaldehyde resin to ultra-thin high-density fiberboard under high temperature and pressure; the basis weight of the decorative paper is 70-120 g / m². 2 The impregnation amount is 110-130%, the volatile matter content is 5.5-7.5%, the pre-curing degree is 40-60%, and the formaldehyde emission is ≤0.3mg / L; the ultra-thin high-density fiberboard has a thickness of 0.8-1.2mm and a density of 0.8-1.2g / cm³. 3 The moisture content is 4.0%–9.0%, and the formaldehyde emission is ≤0.050 mg / m³. 3 The back has ventilation holes with a depth and diameter of 0.3-0.5mm and a spacing of 5mm. High-temperature and high-pressure bonding forms a single-sided ultra-thin high-density fiberboard as the surface layer, ensuring that large-sized curved decorative door panels possess the excellent performance of melamine board and achieve color matching, while simultaneously enhancing resistance to deformation and cracking. The selection of specifications for both the decorative paper and the ultra-thin high-density fiberboard ensures good dimensional stability and resistance to deformation and cracking.

[0014] The impregnated decorative paper and fiberboard used in this invention have low formaldehyde emissions, and the composite adhesive is a formaldehyde-free, highly flexible, and highly adhesive vinyl acetate-ethylene copolymer emulsion, which not only ensures the performance of large-size curved decorative door panels, but also reduces the formaldehyde emissions of large-size curved decorative door panels.

[0015] The present invention also provides a method for preparing the large-size curved decorative door panel, comprising the following steps: S1. Wood fiber and polyester fiber are mixed evenly by high-speed airflow, adhesive and foaming agent are applied, and after secondary mixing, airflow laying and hot pressing are carried out to obtain high-toughness fiberboard. S2. Decorative base paper is impregnated with urea-formaldehyde resin impregnation solution and dried; coated with amine-formaldehyde resin coating solution, dried and cut to obtain impregnated decorative film paper; S3. Impregnated decorative film paper is laid on the front of the ultra-thin high-density fiberboard, pressed and adhered, and after the board is trimmed, the back is softened and then wrapped with film to shape it to obtain a single-sided ultra-thin high-density fiberboard. S4. Soften and balance the high-toughness fiberboard, single-sided ultra-thin high-density fiberboard and eucalyptus veneer. S5. High-toughness fiberboard, single-sided ultra-thin high-density fiberboard and eucalyptus veneer that have completed softening treatment are coated with environmentally friendly adhesive on one side in the symmetrical order of the internal structure of the arc-shaped door panel, and stacked in the concave cavity of the lower mold of the high-frequency bending press. S6. Start the high-frequency bending press, set the high-frequency hot bending process, and use the upper mold convex mold corresponding to the lower mold to press and bond the stacked plates placed on the lower mold to obtain the arc-shaped decorative door panel workpiece. S7. Take out the curved decorative door panel workpiece after high-frequency pressing, stand it upright, and let it cool naturally for more than 2 hours; then, after cutting, fine trimming, edge sealing, and inspection, the finished curved decorative door panel is obtained.

[0016] The above-mentioned material preparation method features rapid high-frequency heating and short curing time, significantly shortening the entire hot-pressing molding cycle compared to traditional methods. Material pretreatment and precise process control greatly reduce defects such as cracking, blistering, and delamination during bending. This ensures both the flexibility and plasticity required for large-size curved door panels, while also guaranteeing sufficient rigidity, dimensional stability, and surface hardness in the finished product.

[0017] Preferably, in step S1, the wood fiber has a length of 1–6 mm, the polyester fiber has a length of 4–6 mm, and the mass ratio of wood fiber to polyester fiber is 3:0.2–0.4; the adhesive is a polymer formed by mixing isocyanate and polyethylene glycol in a mass ratio of 1:3–5, and the amount of adhesive added is 10–20% of the total fiber mass; the foaming agent is azodicarbonamide, and the amount added is 6–10% of the adhesive mass; the hot pressing process is performed at a pressure of 2–5 MPa, a temperature of 145–155°C, and a time of 500–600 s. Specific fiber lengths and ratios can make it both tough and strong. Adding polyester fibers can increase toughness and crack resistance. The adhesive is a polymer formed by the chemical reaction of isocyanate and polyethylene glycol in a ratio of 1:3 to 5. Adding polyethylene glycol improves the flexibility of the adhesive. Azodicarbonamide decomposes when heated to release gases such as nitrogen, ammonia, and carbon monoxide to foam the isocyanate adhesive, allowing the adhesive to penetrate more fully on the fiber surface, thereby obtaining a lightweight and porous fiber material.

[0018] Preferably, in step S2, the molar ratio of formaldehyde to urea in the urea-formaldehyde resin (F / U) is 0.9–1.0, and the mass ratio of acrylic emulsion to urea in the urea-formaldehyde resin is 0.4–0.5:1; the impregnation speed is 25–35 m / min, the impregnation amount is 60–70%, the drying temperature is 125–135°C, and the drying time is 25–35 s. The molar ratio of formaldehyde to urea in the urea-formaldehyde resin (F / U) of 0.9–1.0 reduces the amount of formaldehyde used and lowers formaldehyde release. The mass ratio of acrylic emulsion to urea in the urea-formaldehyde resin of 0.4–0.5:1 improves both the adhesive properties and the flexibility and tensile strength of the impregnated decorative paper.

[0019] Preferably, in step S2, the amine-formaldehyde resin coating liquid comprises the following raw materials in parts by weight: 100 parts amine-formaldehyde resin, 2-5 parts polyethylene emulsion, 0.5-0.7 parts curing agent, 0.1-0.3 parts penetrant, and 0.1-0.3 parts release agent; the amine-formaldehyde resin comprises the following raw materials in parts by weight: 100 parts melamine, 100 parts formaldehyde, 15-20 parts diethylene glycol, 15-20 parts glycerol, 6-10 parts tris(2-hydroxyethyl) isocyanurate, and 30-40 parts water; the coating speed is 25-35 m / min, the impregnation amount is 50-60%, the drying temperature is 135-145℃, and the drying time is 40-50 s. Polyethylene emulsion can enhance the toughness and strength of impregnated decorative paper. Tris(2-hydroxyethyl) isocyanurate has multiple active hydroxyl groups, which can react with hydroxymethyl, amino and other groups on melamine, and then be added to the resin crosslinking system, thereby improving the adhesion and flexibility of the amine-formaldehyde resin coating liquid. The improved adhesion allows the impregnated decorative paper to be tightly bonded to ultra-thin high-density fiberboard, while the improved flexibility can reduce the hardness of melamine resin after curing. Combined with diethylene glycol and glycerol, the flexibility of the impregnated decorative paper can be further enhanced to achieve a curved surface without cracking.

[0020] Preferably, in step S3, during pressing, the back of the ultra-thin high-density fiberboard contacts a 40-80 mesh steel wire mesh. The pressing process is as follows: pressure 10-18 MPa, temperature 170-180°C, time 18-20 seconds; the softening treatment involves spraying 30-50 g / m² of material onto the surface. 2 The softening agent comprises the following raw materials by weight percentage: acetic acid 20-25%, glycerin 5-10%, diethylene glycol 5-10%, with the remainder water to bring the total to 100%. The setting process involves pressing the material down with an iron block measuring 2900*1300mm and weighing 1 ton, with a setting time of 24-72 hours. The softening treatment involves spraying 30-50 g / m³ of softening agent. 2 The softener not only replenishes moisture to reduce deformation but also increases its flexibility and plasticity. The iron block is pressed firmly to prevent deformation during cooling.

[0021] Preferably, in S4, the softening treatment involves spraying a surface with 10–20 g / m³ of water. 2 A softening agent is used, and the conditioning and balancing time is 8–24 hours, controlling the material's moisture content to 8–20%. The softening treatment involves spraying 10–20 g / m² of the surface. 2 A softener further improves flexibility and prevents cracking and breakage during curved bending; the moisture content is balanced, as too low a moisture content will easily cause cracking during subsequent processing, while too high a moisture content will easily cause swelling and reduce strength.

[0022] Preferably, in step S5, the coating amount of the environmentally friendly adhesive is 250–300 g / m². 2Apply the adhesive and heat press it within 20 minutes; avoid the adhesive pre-curing affecting the bonding strength.

[0023] Preferably, in step S6, a 1mm thick silicone sheet is placed on the bottom and top of the laminate to increase cushioning and prevent the surface layer from cracking during bending. The upper and lower dies of the high-frequency bending press have corresponding radii of curvature of 32-300mm. The hot bending process involves a pressure of 6-12MPa, a temperature of 90-120℃, and a time of 20-40 minutes, with pressure applied in three stages. This segmented pressure application optimizes the distribution of balanced forces, preventing local deformation or cracking and improving structural stability and dimensional accuracy. The "three-stage pressure application" specifically refers to applying pressure three times to reach the bottom, rather than all at once. For example, if the target radius of curvature is 100mm and the final pressure is 10MPa: the first pressure is applied to 6MPa, resulting in a radius of curvature of 300mm; the second pressure is applied to 8MPa, resulting in a radius of curvature of 200mm; and the third pressure is applied to 10MPa, resulting in a radius of curvature of 100mm. By gradually increasing the pressure in three stages, the material undergoes plastic deformation in three phases, ultimately achieving the target shape (radius of curvature 100mm). Each pressurization is a further step in precise shaping based on the previous deformation.

[0024] Preferably, in S6, electrode plates are provided on the surfaces of the upper and lower dies of the high-frequency bending press. During the high-frequency hot bending process, electromagnetic waves are generated between the upper and lower dies, producing an alternating magnetic field. The wavelength of the electromagnetic waves is 10–1000 m, and the frequency is 10 kHz–200 MHz. The alternating magnetic field interacts with the polar water molecules in the material, generating induced currents (eddy currents) within the material, causing it to heat up. As the material temperature rises, its molecular thermal motion intensifies, increasing its plasticity and making it easier to bend. Pressure is applied to the heated material to bend it according to the predetermined die shape. The electrode plates contain a memory alloy mesh, which is connected to a control panel via micro-wire connectors. This allows for real-time monitoring of the pressure, temperature, and curvature during the hot bending process, and parameter adjustments based on the monitoring data to ensure product quality.

[0025] Compared with the prior art, this application has the following technical effects: 1. This invention combines the advantages of single-sided ultra-thin high-density fiberboard, high-toughness fiberboard, and plywood through a three-stage pressurization and real-time monitoring and adjustment high-frequency hot bending process, achieving integrated molding. This process results in more uniform pressure and temperature, more stable structure, and more precise dimensional control. It also ensures a more balanced distribution of internal stress in the board, significantly reducing the risk of deformation and cracking, minimizing seams, and effectively resisting curvature deformation caused by changes in environmental temperature and humidity.

[0026] 2. The face and back panels of this invention are made of high-toughness fiberboard with a three-dimensional porous structure, which will not break when bent or stretched, thus solving the anisotropy problem of eucalyptus veneer. The core board is plywood with an odd-numbered symmetrical structure, and the fibers of adjacent veneer layers are arranged perpendicularly to each other, which can effectively suppress the cracking problem of eucalyptus veneer during use, and also effectively solve the problem of wavy texture on the board surface. The single-sided ultra-thin high-density fiberboard has a concave-convex structure design that forms a glue nail structure between the veneer layer and the face and back panels, ensuring a firm bond between the two; the ventilation holes facilitate the release of moisture during pressing to ensure the quality of the board surface, while improving the softening effect and bonding strength.

[0027] 3. During the preparation of the finished product of this invention, the heating is rapid and uniform, the energy consumption is low, the production process is precisely controlled and highly efficient, and the resulting large-size curved decorative door panel can reach a size of 2770×1070mm. It has an exquisite appearance, strong decorative effect, and high dimensional accuracy. It also has excellent structural stability and environmental protection performance. It is free of wavy lines, rebound, delamination and cracking, fully meeting the quality requirements of the high-end customized home furnishing market for large-size curved decorative door panels. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the multi-layer structure of the large-size arc-shaped decorative door panel of the present invention; Figure 2 This is a schematic diagram of the structure of the single-sided ultrathin high-density fiberboard of the present invention; Figure 3 This is a schematic diagram of the plywood assembly structure of the present invention; Figure 4 This is a photograph of the actual large-size curved decorative door panel of the present invention.

[0029] Figure Labels 1. Single-sided ultra-thin high-density fiberboard; 2. Environmentally friendly adhesives; 3. High-toughness fiberboard; 4. Plywood; 11. Impregnated decorative film paper; 12. Ultra-thin high-density fiberboard; 13. Ventilation holes; 14. Concave-convex structure; 31. Horizontal eucalyptus veneer; 32. Longitudinal eucalyptus veneer. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0031] In the following description, the embodiments of this application are for illustrative purposes and not for limiting purposes, so as to provide a thorough understanding of the embodiments. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known preparation methods have been omitted so as not to obscure the description of the embodiments of this application with unnecessary details. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are all commercially available.

[0032] It should also be understood that the term "and / or" as used in the specification of embodiments of this application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means two or more.

[0033] This section only introduces content related to the inventive points; other details can be obtained from relevant technologies and will not be described in detail here. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0034] Example 1: This embodiment describes the preparation of a large-size curved decorative door panel. The specific process is as follows: S1. Wood fibers and polyester fibers are uniformly mixed by high-speed airflow, adhesive and foaming agent are applied, and after secondary mixing, airflow-laid hot pressing is performed to obtain a high-toughness fiberboard; the length of the wood fibers is 1-6 mm, the length of the polyester fibers is 4-6 mm, and the mass ratio of wood fibers to polyester fibers is 3:0.4; the adhesive is a polymer formed by the chemical reaction of isocyanate and polyethylene glycol in a mass ratio of 1:4, and the amount of adhesive added is 15% of the total fiber mass; the foaming agent is azodicarbonamide, and the amount added is 8% of the adhesive mass; the hot pressing process is a pressure of 3 MPa, a temperature of 150℃, and a time of 600 s.

[0035] S2. Decorative base paper is impregnated with urea-formaldehyde resin impregnation solution and dried; coated with urea-formaldehyde resin coating solution, dried and cut to obtain impregnated decorative film paper; the molar ratio of formaldehyde to urea in the urea-formaldehyde resin is F / U 0.95, the mass ratio of acrylic emulsion to urea in the urea-formaldehyde resin is 0.45:1, the impregnation speed is 30m / min, the drying temperature is 130℃, the drying time is 30s, and the impregnation amount is 65%. The amine-formaldehyde resin coating liquid comprises the following raw materials in parts by weight: 100 parts amine-formaldehyde resin, 3 parts polyethylene emulsion, 0.6 parts curing agent, 0.2 parts penetrant, and 0.2 parts release agent; the amine-formaldehyde resin comprises the following raw materials in parts by weight: 100 parts melamine, 100 parts formaldehyde, 16 parts diethylene glycol, 17 parts glycerol, 8 parts tris(2-hydroxyethyl) isocyanurate, and 36 parts water; the coating speed is 30 m / min, the drying temperature is 140℃, the drying time is 45 s, and the impregnation amount is 55%.

[0036] S3. Impregnated decorative film paper is laid on the front side of the ultra-thin high-density fiberboard and pressed. During pressing, the back side of the ultra-thin high-density fiberboard is in contact with an 80-mesh steel wire mesh. Pressing process: pressure 15MPa, temperature 170℃, time 20S; after trimming the edges of the board, the back side is softened by spraying 40g / m² of adhesive onto the surface. 2 A softener, comprising the following raw materials by weight percentage: acetic acid 23%, glycerin 7%, diethylene glycol 8%, and the remainder purified water to make up to 100%; after film wrapping and shaping, a single-sided ultra-thin high-density fiberboard is obtained; the shaping is achieved by pressing with an iron block of 2900*1300mm and weighing 1 ton for 48 hours.

[0037] S4. The high-toughness fiberboard, single-sided ultra-thin high-density fiberboard, and eucalyptus veneer undergo a softening treatment to achieve a balanced condition; the softening treatment involves spraying a 15g / m² layer onto the surface. 2 The softening agent has a conditioning and balancing time of 16 hours, and the moisture content of the material is controlled at 14%.

[0038] S5. High-toughness fiberboard, single-sided ultra-thin high-density fiberboard, and eucalyptus veneer that have undergone softening treatment are coated with environmentally friendly adhesive on one side in a symmetrical order according to the internal structure of the curved door panel, and stacked in the concave cavity of the lower mold of a high-frequency bending press; the coating amount of the environmentally friendly adhesive is 280g / m². 2 Apply the adhesive and heat press it on the machine within 20 minutes.

[0039] S6. Start the high-frequency bending press, set the high-frequency hot bending process, and use the upper mold convex mold corresponding to the lower mold to press and bond the stacked plates placed on the lower mold to obtain an arc-shaped decorative door panel workpiece; place a 1mm thick silicone sheet on the bottom and top of the stacked plates; the curvature radius of the bending arc of the upper and lower molds of the high-frequency bending press is 60mm and they are matched accordingly; the hot bending process is a pressure of 6-9MPa, a temperature of 100℃, and a time of 30min, with pressure applied in three stages to the bottom. The surfaces of the upper and lower molds of the high-frequency bending press are equipped with electrode plates. During the high-frequency hot bending process, electromagnetic waves are generated between the upper and lower molds, producing an alternating magnetic field. The wavelength of the electromagnetic waves is 10-1000m, and the frequency is 10 kHz-200MHz. The electrode plates have a built-in shape memory alloy mesh, which is connected to the control panel through a micro wire connector.

[0040] S7. Take out the curved decorative door panel workpiece after high-frequency pressing, stand it upright, and let it cool naturally for more than 2 hours; then, after cutting, fine finishing, edge sealing, and inspection, the finished large-size curved decorative door panel is obtained.

[0041] Example 2: This embodiment describes the preparation of a large-size curved decorative door panel. The specific process is as follows: S1. Wood fibers and polyester fibers are uniformly mixed by high-speed airflow, adhesive and foaming agent are applied, and after secondary mixing, airflow-laid hot pressing is performed to obtain a high-toughness fiberboard; the length of the wood fibers is 1-6 mm, the length of the polyester fibers is 4-6 mm, and the mass ratio of wood fibers to polyester fibers is 3:0.2; the adhesive is a polymer formed by the chemical reaction of isocyanate and polyethylene glycol in a mass ratio of 1:5, and the amount of adhesive added is 10% of the total fiber mass; the foaming agent is azodicarbonamide, and the amount added is 7% of the adhesive mass; the hot pressing process is a pressure of 4 MPa, a temperature of 155℃, and a time of 500 s.

[0042] S2. Decorative base paper is impregnated with urea-formaldehyde resin impregnation solution and dried; coated with urea-formaldehyde resin coating solution, dried and cut to obtain impregnated decorative film paper; the molar ratio of formaldehyde to urea in the urea-formaldehyde resin is 1.0, the mass ratio of acrylic emulsion to urea in the urea-formaldehyde resin is 0.5:1, the impregnation speed is 35m / min, the drying temperature is 125℃, the drying time is 35s, and the impregnation amount is 60%. The amine-formaldehyde resin coating liquid comprises the following raw materials in parts by weight: 100 parts amine-formaldehyde resin, 5 parts polyethylene emulsion, 0.7 parts curing agent, 0.3 parts penetrant, and 0.3 parts release agent; the amine-formaldehyde resin comprises the following raw materials in parts by weight: 100 parts melamine, 100 parts formaldehyde, 20 parts diethylene glycol, 15 parts glycerol, 6 parts tris(2-hydroxyethyl) isocyanurate, and 30 parts water; the coating speed is 25 m / min, the drying temperature is 145℃, the drying time is 40 s, and the impregnation amount is 60%.

[0043] S3. Impregnated decorative film paper is laid on the front side of the ultra-thin high-density fiberboard and pressed. During pressing, the back side of the ultra-thin high-density fiberboard is in contact with a 60-mesh steel wire mesh. Pressing process: pressure 18MPa, temperature 170℃, time 20S; after trimming the edges of the board, the back side is softened by spraying 50g / m² of adhesive onto the surface. 2 A softening agent comprising the following raw materials by weight percentage: 25% acetic acid, 10% glycerol, 10% diethylene glycol, with the remainder being purified water to bring the total to 100%; a single-sided ultra-thin high-density fiberboard is obtained after being wrapped and shaped in a film; the shaping is achieved by pressing it with an iron block measuring 2900*1300mm and weighing 1 ton for 72 hours.

[0044] S4. The high-toughness fiberboard, single-sided ultra-thin high-density fiberboard, and eucalyptus veneer undergo a softening treatment to achieve a balanced condition; the softening treatment involves spraying a 10g / m² layer onto the surface. 2 The softener, the conditioning and balancing time is 24 hours, and the moisture content of the material is controlled at 8%.

[0045] S5. High-toughness fiberboard, single-sided ultra-thin high-density fiberboard, and eucalyptus veneer that have undergone softening treatment are coated with environmentally friendly adhesive on one side in a symmetrical order according to the internal structure of the curved door panel, and then stacked in the concave cavity of the lower mold of a high-frequency bending press; the coating amount of the environmentally friendly adhesive is 250g / m². 2 Apply the adhesive and heat press it on the machine within 20 minutes.

[0046] S6. Start the high-frequency bending press, set the high-frequency hot bending process, and use the upper mold convex mold corresponding to the lower mold to press and bond the stacked plates placed on the lower mold to obtain an arc-shaped decorative door panel workpiece; place a 1mm thick silicone sheet on the bottom and top of the stacked plates; the curvature radius of the bending arc of the upper and lower molds of the high-frequency bending press is 90mm and they are matched accordingly; the hot bending process is a pressure of 6-12MPa, a temperature of 120℃, and a time of 20min, with pressure applied in three stages to the bottom. The surfaces of the upper and lower molds of the high-frequency bending press are equipped with electrode plates. During the high-frequency hot bending process, electromagnetic waves are generated between the upper and lower molds, producing an alternating magnetic field. The wavelength of the electromagnetic waves is 10-1000m, and the frequency is 10 kHz-200MHz. The electrode plates have a built-in shape memory alloy mesh, which is connected to the control panel through a micro wire connector.

[0047] S7. Take out the curved decorative door panel workpiece after high-frequency pressing, stand it upright, and let it cool naturally for more than 2 hours; then, after cutting, fine finishing, edge sealing, and inspection, the finished large-size curved decorative door panel is obtained.

[0048] Example 3: This embodiment describes the preparation of a large-size curved decorative door panel. The specific process is as follows: S1. Wood fibers and polyester fibers are mixed evenly by high-speed airflow, adhesive and foaming agent are applied, and after secondary mixing, airflow-laid hot pressing is performed to obtain a high-toughness fiberboard; the length of the wood fibers is 1-6 mm, the length of the polyester fibers is 4-6 mm, and the mass ratio of wood fibers to polyester fibers is 3:0.3; the adhesive is a polymer formed by the chemical reaction of isocyanate and polyethylene glycol in a mass ratio of 1:3, and the amount of adhesive added is 20% of the total fiber mass; the foaming agent is azodicarbonamide, and the amount added is 10% of the adhesive mass; the hot pressing process is a pressure of 3 MPa, a temperature of 145℃, and a time of 600 s.

[0049] S2. Decorative base paper is impregnated with urea-formaldehyde resin impregnation solution and dried; coated with urea-formaldehyde resin coating solution, dried and cut to obtain impregnated decorative film paper; the molar ratio of formaldehyde to urea in the urea-formaldehyde resin is F / U is 0.9, the mass ratio of acrylic emulsion to urea in the urea-formaldehyde resin is 0.4:1, the impregnation speed is 25m / min, the drying temperature is 135℃, the drying time is 25S, and the impregnation amount is 70%. The amine-formaldehyde resin coating liquid comprises the following raw materials in parts by weight: 100 parts amine-formaldehyde resin, 2 parts polyethylene emulsion, 0.5 parts curing agent, 0.1 parts penetrant, and 0.1 parts release agent; the amine-formaldehyde resin comprises the following raw materials in parts by weight: 100 parts melamine, 100 parts formaldehyde, 15 parts diethylene glycol, 20 parts glycerol, 10 parts tris(2-hydroxyethyl) isocyanurate, and 40 parts water; the coating speed is 35 m / min, the drying temperature is 135℃, the drying time is 50 s, and the impregnation amount is 50%.

[0050] S3. Impregnated decorative film paper is laid on the front side of the ultra-thin high-density fiberboard and pressed. During pressing, the back side of the ultra-thin high-density fiberboard is in contact with a 40-mesh steel wire mesh. Pressing process: pressure 10MPa, temperature 180℃, time 18S; after trimming the edges of the board, the back side is softened by spraying 30g / m² of adhesive onto the surface. 2 A softener, comprising the following raw materials by weight percentage: acetic acid 20%, glycerin 5%, diethylene glycol 5%, and the remainder purified water to make up to 100%; after film wrapping and shaping, a single-sided ultra-thin high-density fiberboard is obtained; the shaping is achieved by pressing with an iron block of 2900*1300mm and weighing 1 ton for 24 hours.

[0051] S4. The high-toughness fiberboard, single-sided ultra-thin high-density fiberboard, and eucalyptus veneer undergo a softening treatment to achieve a balanced condition; the softening treatment involves spraying a 20g / m² layer onto the surface. 2 The softening agent has a conditioning and balancing time of 8 hours, and the moisture content of the material is controlled at 20%.

[0052] S5. High-toughness fiberboard, single-sided ultra-thin high-density fiberboard, and eucalyptus veneer that have undergone softening treatment are coated with environmentally friendly adhesive on one side in a symmetrical order according to the internal structure of the curved door panel, and then stacked in the concave cavity of the lower mold of a high-frequency bending press; the coating amount of the environmentally friendly adhesive is 300g / m². 2 Apply the adhesive and heat press it on the machine within 20 minutes.

[0053] S6. Start the high-frequency bending press, set the high-frequency hot bending process, and use the upper mold convex mold corresponding to the lower mold to press and bond the stacked plates placed on the lower mold to obtain an arc-shaped decorative door panel workpiece; place a 1mm thick silicone sheet on the bottom and top of the stacked plates; the curvature radius of the bending arc of the upper and lower molds of the high-frequency bending press is 120mm and they are matched accordingly; the hot bending process is a pressure of 6-10MPa, a temperature of 90℃, and a time of 40min, with pressure applied in three stages to the bottom. The surfaces of the upper and lower molds of the high-frequency bending press are equipped with electrode plates. During the high-frequency hot bending process, electromagnetic waves are generated between the upper and lower molds, producing an alternating magnetic field. The wavelength of the electromagnetic waves is 10-1000m and the frequency is 10 kHz-200MHz. The electrode plates have a built-in shape memory alloy mesh, which is connected to the control panel through a micro wire connector.

[0054] S7. Take out the curved decorative door panel workpiece after high-frequency pressing, stand it upright, and let it cool naturally for more than 2 hours; then, after cutting, fine finishing, edge sealing, and inspection, the finished large-size curved decorative door panel is obtained.

[0055] Comparative Example 1: Compared to Example 1, in S5, after the softened boards are coated with adhesive and stacked, they are placed in an arc-shaped mold for cold pressing and curing. The preceding steps are the same as in Example 1.

[0056] Comparative Example 2: Compared to Example 1, the core board was made of oriented strand board (OSB), the facing layer was single-sided OSB, and the surface was covered with melamine-impregnated paper. Other steps were performed as in Example 1. During high-frequency hot bending, cracks were found in both the core board and the facing layer, indicating that this material was unsuitable and no further performance testing was conducted.

[0057] Performance testing Table 1 Performance Test Results Based on the teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A large-size curved decorative door panel, characterized in that, The large-size curved decorative door panel is formed by molding the panel, core board, base board and decorative layer in one step using a high-frequency bending press; the panel and base board are high-toughness fiberboard with a three-dimensional porous structure, the core board is plywood, and the decorative layer is single-sided ultra-thin high-density fiberboard. The front and back panels are made by uniformly mixing wood fiber and polyester fiber, applying formaldehyde-free adhesive and foaming agent, and then air-flow laying and hot pressing. The plywood is made of eucalyptus rotary-cut veneer as raw material and bonded with environmentally friendly adhesive. The number of layers is odd, and the fiber direction of adjacent veneer layers is perpendicular to each other. The back of the single-sided ultra-thin high-density fiberboard has a concave-convex structure and ventilation holes. The concave-convex structure consists of multiple convex structures arranged in a matrix and alternately set with concave structures in between. The ventilation holes are located above the concave-convex structure.

2. The large-size curved decorative door panel as described in claim 1, characterized in that, The panel and base plate are made of the same material and have a thickness of 1.0–2.0 mm and a density of 0.3–0.5 g / cm³. 3 Formaldehyde emission ≤0.025mg / m³ 3 The plywood has a moisture content of 6.0–16.0% and a formaldehyde emission level ≤0.050 mg / m³. 3 .

3. The large-size curved decorative door panel as described in claim 1, characterized in that, The single-sided ultra-thin high-density fiberboard is made by bonding decorative paper impregnated with urea-formaldehyde resin and coated with amine-formaldehyde resin to ultra-thin high-density fiberboard under high temperature and pressure; the base paper weight of the decorative paper is 70-120 g / m². 2 The impregnation amount is 110-130%, the volatile matter content is 5.5-7.5%, the pre-curing degree is 40-60%, and the formaldehyde emission is ≤0.3mg / L; the ultra-thin high-density fiberboard has a thickness of 0.8-1.2mm and a density of 0.8-1.2g / cm³. 3 The moisture content is 4.0%–9.0%, and the formaldehyde emission is ≤0.050 mg / m³. 3 The back has ventilation holes with a depth and diameter of 0.3 to 0.5 mm and a spacing of 5 mm.

4. The method for preparing the large-size arc-shaped decorative door panel according to claim 1, characterized in that, Includes the following steps: S1. Wood fiber and polyester fiber are mixed evenly by high-speed airflow, adhesive and foaming agent are applied, and after secondary mixing, airflow laying and hot pressing are carried out to obtain high-toughness fiberboard. S2. Decorative base paper is impregnated with urea-formaldehyde resin impregnation solution and dried; coated with amine-formaldehyde resin coating solution, dried and cut to obtain impregnated decorative film paper; S3. Impregnated decorative film paper is laid on the front of the ultra-thin high-density fiberboard, pressed and adhered, and after the board is trimmed, the back is softened and then wrapped with film to shape it to obtain a single-sided ultra-thin high-density fiberboard. S4. Soften and balance the high-toughness fiberboard, single-sided ultra-thin high-density fiberboard and eucalyptus veneer. S5. High-toughness fiberboard, single-sided ultra-thin high-density fiberboard and eucalyptus veneer that have completed softening treatment are coated with environmentally friendly adhesive on one side in the symmetrical order of the internal structure of the arc-shaped door panel, and stacked in the concave cavity of the lower mold of the high-frequency bending press. S6. Start the high-frequency bending press, set the high-frequency hot bending process, and use the upper mold convex mold corresponding to the lower mold to press and bond the stacked plates placed on the lower mold to obtain the arc-shaped decorative door panel workpiece. S7. Take out the curved decorative door panel workpiece, stand it upright, and let it cool naturally for more than 2 hours; then, after cutting, fine finishing, edge sealing, and inspection, the finished large-size curved decorative door panel is obtained.

5. The method for preparing a large-size curved decorative door panel as described in claim 4, characterized in that, In S1, the wood fiber has a length of 1-6 mm, the polyester fiber has a length of 4-6 mm, and the mass ratio of wood fiber to polyester fiber is 3:0.2-0.4; the adhesive is a polymer formed by mixing isocyanate and polyethylene glycol in a mass ratio of 1:3-5, and the amount of adhesive added is 10-20% of the total fiber mass; the foaming agent is azodicarbonamide, and the amount added is 6-10% of the adhesive mass; the hot pressing process is performed at a pressure of 2-5 MPa, a temperature of 145-155℃, and a time of 500-600 s.

6. The method for preparing a large-size curved decorative door panel as described in claim 4, characterized in that, In S2, the molar ratio of formaldehyde to urea in the urea-formaldehyde resin (F / U) is 0.9–1.0, and the mass ratio of acrylic emulsion to urea in the urea-formaldehyde resin is 0.4–0.5:1; the impregnation speed is 25–35 m / min, the impregnation amount is 60–70%, the drying temperature is 125–135 °C, and the drying time is 25–35 s.

7. The method for preparing a large-size curved decorative door panel as described in claim 4, characterized in that, In S2, the amine-formaldehyde resin coating liquid comprises the following raw materials in parts by weight: 100 parts amine-formaldehyde resin, 2-5 parts polyethylene emulsion, 0.5-0.7 parts curing agent, 0.1-0.3 parts penetrant, and 0.1-0.3 parts release agent; the amine-formaldehyde resin comprises the following raw materials in parts by weight: 100 parts melamine, 100 parts formaldehyde, 15-20 parts diethylene glycol, 15-20 parts glycerol, 6-10 parts tris(2-hydroxyethyl) isocyanurate, and 30-40 parts water; the coating speed is 25-35 m / min, the impregnation amount is 50-60%, the drying temperature is 135-145℃, and the drying time is 40-50 s.

8. The method for preparing a large-size curved decorative door panel as described in claim 4, characterized in that, In step S3, during the pressing process, the back of the ultra-thin high-density fiberboard comes into contact with a 40-80 mesh steel wire mesh. The pressing process involves a pressure of 10-18 MPa, a temperature of 170-180°C, and a time of 18-20 seconds. The softening treatment involves spraying 30-50 g / m² of material onto the surface. 2 The softener comprises the following raw materials by weight percentage: acetic acid 20-25%, glycerin 5-10%, diethylene glycol 5-10%, and water to make up to 100%; the setting is done by pressing with an iron block of 2900*1300mm and weighing 1 ton, and the setting time is 24-72 hours. And / or, In S4, the softening treatment involves spraying a surface with 10–20 g / m³ of water. 2 The softening agent is used, and the conditioning and balancing time is 8-24 hours, while the moisture content of the material is controlled at 8-20%.

9. The method for preparing a large-size curved decorative door panel as described in claim 4, characterized in that, In S5, the coating amount of the environmentally friendly adhesive is 250-300 g / m². 2 Apply the adhesive and heat press within 20 minutes. And / or, In S6, a 1mm thick silicone sheet is placed at the bottom and top of the laminated plate. The curvature radius of the upper and lower dies of the high-frequency bending press is 32-300mm and they are matched accordingly. The hot bending process is a pressure of 6-12MPa, a temperature of 90-120℃, a time of 20-40min, and is carried out in three stages to the bottom.

10. The method for preparing a large-size curved decorative door panel as described in claim 4, characterized in that, In S6, the surfaces of the upper and lower dies of the high-frequency bending press are provided with electrode plates. During the high-frequency hot bending process, electromagnetic waves are generated between the upper and lower dies, producing an alternating magnetic field. The wavelength of the electromagnetic waves is 10 to 1000 m, and the frequency is 10 kHz to 200 MHz. The electrode plates have a built-in shape memory alloy wire mesh, which is connected to the control panel through a micro wire connector.

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