Flame-retardant reconstituted decorative material and method for producing the same

Abstract

This invention provides a flame-retardant reconstituted decorative material and its preparation method, comprising: applying a melamine-modified urea-formaldehyde resin adhesive containing a certain amount and proportion of nano-montmorillonite and hydrotalcite fillers to poplar veneer, followed by cold pressing after assembly to obtain a first set of wood blocks, and then slicing the first set of wood blocks into reconstituted veneers of a certain thickness. A flame-retardant melamine-modified urea-formaldehyde resin adhesive is synthesized using cyclodextrin, formaldehyde, urea, and melamine; this adhesive is applied to the reconstituted veneers in a certain amount; after assembly, cold pressing is performed for a period of time to obtain reconstituted wood blocks; and the reconstituted wood blocks are then sliced ​​to obtain the flame-retardant reconstituted decorative material. This method solves the problems of poor bonding strength, poor smoke suppression, and glue spots on the surface of traditional flame-retardant reconstituted decorative materials.

Description

Technical Field

[0001] This invention relates to the field of engineered wood products, specifically to flame-retardant reconstituted decorative materials and their preparation methods. Background Technology

[0002] With increasingly stringent safety requirements for interior decoration in public buildings and residences, flame-retardant wood-based decorative materials are receiving growing attention. While traditional flame-retardant reconstituted decorative materials can improve the flame-retardant properties of wood to some extent, they still have significant shortcomings in areas such as bonding strength, smoke release control, and surface finish. On the one hand, there is poor compatibility between conventional flame retardants and adhesive systems, leading to decreased bonding strength; on the other hand, some organic flame retardants are prone to decomposition at high temperatures, producing toxic fumes and having limited smoke suppression effects. Furthermore, because flame retardant particles tend to agglomerate and distribute unevenly, decorative defects such as glue spots often appear on the surface of the boards, seriously affecting the material's usability and visual appeal.

[0003] Prior patent documents

[0004] CN 117701207 A

[0005] CN 108659760 B Summary of the Invention

[0006] In view of the above-mentioned research and development issues, the present invention aims to provide a flame-retardant reconstituted decorative material and its preparation method. It adopts a flame-retardant system of nanoparticles synergistic with cyclodextrin and a two-step reconstituted process design, which effectively solves the problems of poor smoke suppression, low bonding strength and glue spots in traditional processes while achieving excellent flame retardancy.

[0007] Firstly, a method for preparing a flame-retardant reconstituted decorative material is provided, comprising:

[0008] (1): Prepare inorganic filler adhesive and flame retardant adhesive, wherein,

[0009] (1-1) Inorganic filler adhesives are prepared by the following method:

[0010] Nano-montmorillonite and nano-hydrotalcite are mixed evenly at a mass ratio of 1:1-1.5 and added to melamine-modified urea-formaldehyde resin with a melamine content of 8-11% and a solid content of 50-55% at a mass ratio of 25-30:100. After stirring at room temperature for 5-8 hours, an inorganic filler adhesive is obtained.

[0011] (1-2) The flame-retardant adhesive is prepared by the following method:

[0012] A 37-40% formaldehyde aqueous solution was added to the reaction vessel, and a certain amount of NaOH solution was added to adjust the pH value to 8.4-8.6. Then, the first batch of urea, the first batch of melamine, and cyclodextrin were added. The temperature was raised to 70-80℃ and maintained for 1-2.5 hours. The molar ratio of formaldehyde to the first batch of urea was 0.9-0.96:0.45-0.55. Melamine accounted for 25-35% of the mass of formaldehyde, and cyclodextrin accounted for 30-55% of the mass of formaldehyde.

[0013] Then add the second batch of urea and the second batch of melamine, adjust the pH value to 6.5-6.7 with formic acid solution, and continue to maintain the temperature at 70-80℃ for 1-2.5h. Then adjust the pH value to 8.5-8.7 with a certain amount of NaOH solution. The molar ratio of formaldehyde to the second batch of urea is 0.9-0.96:0.45-0.55, and the second batch of melamine accounts for 8-12% of the mass of formaldehyde. Stop heating and wait for the temperature to drop to room temperature to obtain the flame retardant adhesive.

[0014] (2): Preparation of flame-retardant reconstituted decorative materials:

[0015] (2-1) Apply inorganic filler adhesive to the surface of wood veneer of a certain or different thickness, with an adhesive application rate of 110-125 g / m². 2 After the glued veneer sheets are assembled, they are cold-pressed at a pressure of 0.20-0.25 MPa for 168-180 hours to obtain the first set of timber.

[0016] (2-2) The first group of timber is planed along any side into reconstituted veneers of a certain or different thickness. Then, flame-retardant adhesive is applied to the surface of each reconstituted veneer at a rate of 110-125 g / m². 2 The multiple veneers after being coated with glue are then cold-pressed at a pressure of 0.20-0.25 MPa for 168-180 hours to obtain the second set of timber.

[0017] (2-3) The second group of timber is planed along any side into veneers with a thickness of 0.40-0.60mm to obtain flame-retardant reconstituted decorative material.

[0018] In (1-1), the average particle size of nano-montmorillonite is 50-70 nm, and the average particle size of nano-hydrotalcite is 50-70 nm.

[0019] In (2-1), the wood veneer is any one or a combination of poplar, eucalyptus, and pine, with a thickness of 1.7-1.8 mm and a moisture content of 8-10%.

[0020] In step (2-1), the glued wood veneer is assembled to a thickness of 1.2-1.5m.

[0021] In step (2-2), the first group of timber is planed into reconstituted veneers with a thickness of 1.0-1.2 mm.

[0022] In step (2-2), the glued reconstituted veneer blanks are assembled to a thickness of 1.2-1.5 μm.

[0023] In step (2-1), the blanks are assembled along the wood grain direction, and in step (2-2), the blanks are assembled along the layer grain direction.

[0024] The (2-3) section is cut along the side of the grid.

[0025] A flame-retardant reconstituted decorative material is also provided, which is prepared by any of the above preparation methods.

[0026] According to the present invention, the following beneficial effects can be obtained.

[0027] (1) Significantly improved smoke suppression performance: Based on the synergistic effect of inorganic nanoparticles and cyclodextrin, by introducing nano-montmorillonite and hydrotalcite into melamine-modified urea-formaldehyde resin adhesive, they work together with the cyclodextrin groups in the synthetic adhesive: Inorganic nanoparticles form a stable inert barrier layer at high temperature, effectively blocking heat conduction and the release of combustible gases; The cyclodextrin structure generates a carbon layer and gases (such as ammonia and nitrogen) rich in nitrogen elements during pyrolysis, which dilutes the oxygen concentration in the combustion zone in the early stage of flame spread; The two work together to form a dense and stable "expanded carbon layer", which significantly inhibits the release of smoke and toxic gases, meeting the safety requirements of modern decorative materials for low smoke and environmental protection.

[0028] (2) Two-stage recombination process – a key path to improve structural stability and flame retardant efficiency

[0029] Compared to the traditional one-step pressing method, this invention adopts a two-step method of "first slicing into reconstituted veneers + then reconstituted and pressed with adhesive", which has the following advantages: the first step of reconstituted slicing can evenly distribute nanoparticles and the primary adhesive interface, improving the structural density; the second step uses flame-retardant adhesive for reconstituted veneer, ensuring that the flame-retardant components are concentrated in the key adhesive layer, further enhancing the overall flame-retardant effect; in terms of process, it is beneficial to reduce the accumulation of internal stress, improve dimensional stability and yield.

[0030] (3) Eliminating glue spot defects - the dispersion promoting effect of nanoparticles

[0031] Nanoscale montmorillonite and hydrotalcite provide a good dispersion interface through their layered structure, significantly improving the spreading performance of adhesives on wood surfaces. During slicing and repressing, the particles can act as rheology modifiers and interface modifiers, preventing the migration and aggregation of cyclodextrin components in flame-retardant adhesives. Through dispersion, they can effectively eliminate surface defects such as glue spots and discoloration, enhancing the decorative effect.

[0032] (4) Improved bonding strength - the reaction mechanism between the flame retardant structure and the adhesive molecular chain. The flame retardant is copolymerized from cyclodextrin, melamine, urea and formaldehyde, and has multifunctional groups (-NH2, -OH, -C=N). These groups can form a cross-linking reaction with the urea-formaldehyde resin network during the curing process and embed into the molecular chain to form a dense adhesive network structure. The increased degree of cross-linking enhances the cohesive strength and heat resistance of the adhesive layer. While performing flame retardant modification, it maintains or even improves the bonding strength, overcoming the bottleneck problem that flame retardant modification often leads to "strength sacrifice". Detailed Implementation

[0033] The following describes embodiments of the present invention; however, the present invention is not limited to these embodiments, and various modifications can be made within the scope defined by the claims. Different embodiments or preparation examples, as well as new modifications obtained by combinations of common technical means, should also be considered to be included within the scope of the present invention.

[0034] Raw materials:

[0035] Nano-montmorillonite: Purchased from Jingjiang Kanggaote New Material Technology Co., Ltd.;

[0036] Nano-hydrotalcite: Purchased from Jingjiang Kanggaote New Material Technology Co., Ltd.;

[0037] Melamine-modified urea-formaldehyde resin: purchased from Guangxi Jianxin Wood Industry Group Co., Ltd.

[0038] Cyclodextrin: Purchased from Shandong Tongwang Biotechnology Co., Ltd.

[0039] This embodiment uses a novel cyclodextrin-modified melamine-urea-formaldehyde resin flame-retardant adhesive to prepare flame-retardant reconstituted decorative materials. The preparation includes: adding a 37-40% formaldehyde aqueous solution to a reaction vessel, adding urea in two equal or nearly equal portions, with a molar ratio of formaldehyde to urea of ​​0.9-0.96:1, and adding melamine / cyclodextrin along with the urea.

[0040] The preparation further includes: adding the above-mentioned formaldehyde aqueous solution into a reaction vessel, adding a certain amount of NaOH solution to adjust the pH value to 8.4-8.6, and then adding the first batch of urea (accounting for 45-55% of the total mass of urea), melamine (accounting for 25-35% of the mass of formaldehyde) and cyclodextrin (accounting for 30-55% of the mass of formaldehyde), and heating to 70-80℃ and maintaining it for 1-2.5h;

[0041] Add a second batch of urea (45-55% of the total urea mass) and melamine (8-12% of the formaldehyde mass). Adjust the pH to 6.5-6.7 with formic acid solution and maintain at 70-80℃ for 1-2.5 hours. Then adjust the pH to 8.5-8.7 with a certain amount of NaOH solution. Stop heating and wait for the temperature to drop to room temperature to stop the reaction and obtain the flame-retardant adhesive.

[0042] The following reaction occurs during the above preparation.

[0043] Preparation Example 1:

[0044] A 37% formaldehyde aqueous solution was added to the reactor, and a certain amount of 35% NaOH aqueous solution was added to adjust the pH value to 8.6. Then, the first batch of urea (45% of the total mass of urea, with a molar ratio of formaldehyde to the first batch of urea of ​​0.9:0.45), melamine (25% of the mass of formaldehyde solution), and cyclodextrin (30% of the mass of formaldehyde solution) were added. The temperature was raised to 80℃ and maintained for 2.5 hours.

[0045] A second batch of urea (55% of the total urea mass, with a formaldehyde molar ratio of 0.9:0.55) and melamine (8% of the formaldehyde solution mass) were added. The pH was adjusted to 6.7 with a certain amount of 20% formic acid aqueous solution and kept at 80℃ for 2.5h. Then, the pH was adjusted to 8.7 with a certain amount of 35% NaOH aqueous solution. Heating was stopped and the reaction was stopped after the temperature dropped to room temperature (25℃) to obtain the flame-retardant adhesive.

[0046] Preparation Example 2:

[0047] A 40% formaldehyde aqueous solution was added to the reactor, and a certain amount of 35% NaOH aqueous solution was added to adjust the pH value to 8.4. Then, the first batch of urea (accounting for 55% of the total mass of urea, with a molar ratio of formaldehyde to the first batch of urea of ​​0.96:0.55), melamine (accounting for 35% of the mass of formaldehyde solution), and cyclodextrin (accounting for 55% of the mass of formaldehyde solution) were added. The temperature was raised to 70℃ and maintained for 1 hour.

[0048] A second batch of urea (45% of the total urea mass, with a formaldehyde molar ratio of 0.96:0.45) and melamine (12% of the formaldehyde solution mass) were added. The pH was adjusted to 6.5 with a certain amount of 20% formic acid aqueous solution. The mixture was kept at 70°C for 1 hour. Then, the pH was adjusted to 8.5 with a certain amount of 35% NaOH aqueous solution. Heating was stopped, and the reaction was stopped after the temperature dropped to room temperature (25°C) to obtain the flame-retardant adhesive.

[0049] Preparation Example 3:

[0050] A 37% formaldehyde aqueous solution was added to the reactor, and a certain amount of 35% NaOH aqueous solution was added to adjust the pH value to 8.4. Then, the first batch of urea (accounting for 50% of the total mass of urea, with a molar ratio of formaldehyde to the first batch of urea of ​​0.93:0.5), melamine (accounting for 30% of the mass of formaldehyde solution), and cyclodextrin (accounting for 40% of the mass of formaldehyde solution) were added. The temperature was raised to 75°C and maintained for 2 hours.

[0051] Add a second batch of urea (50% of the total urea mass, with a formaldehyde molar ratio of 0.93:0.5) and melamine (10% of the formaldehyde solution mass). Adjust the pH to 6.5 with a certain amount of 20% formic acid aqueous solution. Maintain the temperature at 75°C for 2 hours. Then adjust the pH to 8.5 with a certain amount of 35% NaOH aqueous solution. Stop heating and wait for the temperature to drop to room temperature (25°C) before stopping the reaction to obtain the flame-retardant adhesive.

[0052] This embodiment further uses the flame-retardant adhesives prepared in Preparation Examples 1 to 3 to prepare flame-retardant reconstituted decorative materials, and the specific preparation is as follows.

[0053] (1) Mix nano-montmorillonite and nano-hydrotalcite at a mass ratio of 1:1-1.5 and add them to melamine-modified urea-formaldehyde resin with a melamine content of 8-11% and a solid content of 50-55%. The mass ratio of inorganic additives to urea-formaldehyde resin is 25-30:100. Stir at room temperature for 5-8 hours to obtain inorganic filler adhesive.

[0054] (2) Apply the above-mentioned inorganic filler adhesive to the surface of wood veneer of a certain or different thickness, with an adhesive application amount of 110-125 g / m². 2 After applying glue, multiple veneers are assembled along the same wood grain direction and then cold-pressed. The cold pressing pressure is 0.20-0.25 MPa and the cold pressing time is 168-180 hours to obtain the first set of timber.

[0055] (3) Plane the first group of timber along any side into reconstituted veneers of a certain or different thickness, and then apply flame-retardant adhesive to the surface of each reconstituted veneer at a rate of 110-125 g / m². 2 After applying the adhesive, the multiple veneers are assembled along the same grain direction and then cold-pressed. The cold-pressing pressure is 0.20-0.25MPa and the cold-pressing time is 168-180h to obtain the second set of timber.

[0056] (4) The second group of timber is sliced ​​into veneers with a thickness of 0.40-0.60mm along any side (preferably along the grid pattern side) to obtain flame-retardant reconstituted decorative material.

[0057] The nano-montmorillonite has an average particle size of 50-70 nm, and the nano-hydrotalcite has an average particle size of 50-70 nm. The wood veneer is 1.7-1.8 mm thick and made of poplar, eucalyptus, pine, etc., with a moisture content of 8-10%. The glued wood veneer is assembled to a thickness of 1.2-1.5 μm, and the first group of timber is sliced ​​into 1.0-1.2 mm thick reconstituted veneer. The glued reconstituted veneer is then assembled to a thickness of 1.2-1.5 μm.

[0058] Example 1:

[0059] (1) Mix nano-montmorillonite with an average particle size of 50-70nm and nano-hydrotalcite with an average particle size of 50-70nm in a mass ratio of 1:1, and add them to melamine-modified urea-formaldehyde resin with a melamine content of 8% and a solid content of 50% in a mass ratio of 25:100. After stirring at room temperature of 25℃ for 5h, an inorganic filler adhesive is obtained.

[0060] (2) The above-mentioned inorganic filler adhesive was applied to the surface of a poplar veneer with a moisture content of 8%, measuring 1.7 mm thick, 2.2 m long (in the grain direction), and 1.2 m wide, with an adhesive application rate of 110 g / m. 2 Multiple veneers after gluing are assembled in the same wood grain direction to a thickness of 1.2m, and then cold-pressed at a pressure of 0.20MPa for 168h to obtain the first group of timber.

[0061] (3) The first group of timber was planed into 1.0 mm thick reconstituted veneers along the width and side, and then the flame-retardant adhesive of Preparation Example 1 was applied to the surface of each reconstituted veneer at a coating weight of 110 g / m². 2 The multiple veneers after gluing are assembled along the same grain direction to a thickness of 1.2m, and then cold-pressed at a pressure of 0.20MPa for 168h to obtain the second set of timber.

[0062] (4) The second group of wood is sliced ​​into 0.40mm thick veneers along the long stripes to obtain flame-retardant reconstituted decorative material.

[0063] performance:

[0064] Peak heat release rate: 105.7 kW / m 2

[0065] Peak smoke release rate: 0.0164 m 2 / s

[0066] Lateral curvature of flame-retardant reconstituted decorative material: 0.089%

[0067] Number of visible adhesive residues per square meter (tested according to GB / T 28998-2012 method): 0

[0068] Example 2:

[0069] (1) Mix nano-montmorillonite with an average particle size of 50-70nm and nano-hydrotalcite with an average particle size of 50-70nm at a mass ratio of 1:1.5, and add them to melamine-modified urea-formaldehyde resin with a melamine content of 11% and a solid content of 55% at a mass ratio of 30:100. After stirring at room temperature of 25℃ for 8 hours, an inorganic filler adhesive is obtained.

[0070] (2) The above-mentioned inorganic filler adhesive is applied to the surface of a 1.8mm thick, 2.2m long (grain direction), and 1.2m wide eucalyptus veneer with a moisture content of 10%, with an adhesive application rate of 125g / m². 2 Multiple veneers after gluing are assembled in the same wood grain direction to a thickness of 1.5m, and then cold-pressed at a pressure of 0.25MPa for 180h to obtain the first group of timber.

[0071] (3) The first group of timber was planed into 1.2mm thick reconstituted veneers along its width and side. Then, the flame-retardant adhesive of Preparation Example 2 was applied to the surface of each reconstituted veneer at a coating weight of 125g / m². 2 The multiple veneers after gluing are assembled along the same grain direction to a thickness of 1.5m, and then cold-pressed at a pressure of 0.25MPa for 180h to obtain the second set of timber.

[0072] (4) The second group of wood is sliced ​​into 0.6mm thick veneers along the long stripes to obtain flame-retardant reconstituted decorative material.

[0073] performance:

[0074] Peak heat release rate: 91.8 kW / m 2

[0075] Peak smoke release rate: 0.0159 m 2 / s

[0076] Lateral curvature of flame-retardant reconstituted decorative material: 0.081%

[0077] Number of visible adhesive residues per square meter (tested according to GB / T 28998-2012 method): 0

[0078] Example 3:

[0079] (1) Mix nano-montmorillonite with an average particle size of 50-70nm and nano-hydrotalcite with an average particle size of 50-70nm at a mass ratio of 1:1.2 and add them to melamine-modified urea-formaldehyde resin with a melamine content of 10% and a solid content of 52% at a mass ratio of 28:100. After stirring at room temperature of 25℃ for 9 hours, an inorganic filler adhesive is obtained.

[0080] (2) The above-mentioned inorganic filler adhesive was applied to the surface of a poplar veneer with a moisture content of 9%, measuring 1.7 mm thick, 2.2 m long (in the grain direction), and 1.2 m wide, with an adhesive application rate of 120 g / m. 2 Multiple veneers with the same wood grain are assembled to a thickness of 1.2m, and then cold-pressed at a pressure of 0.2MPa for 168h to obtain the first set of timber.

[0081] (3) The first group of timber was sliced ​​along its length into 1.2 mm thick reconstituted veneers, and then the flame-retardant adhesive of Preparation Example 3 was applied to the surface of each reconstituted veneer at a coating weight of 120 g / m². 2 The multiple veneers after gluing are assembled along the same grain direction to a thickness of 1.2m, and then cold-pressed at a pressure of 0.2MPa for 168h to obtain the second set of timber.

[0082] (4) The second group of wood is sliced ​​into 0.4mm thick veneers along the long stripes to obtain flame-retardant reconstituted decorative material.

[0083] performance:

[0084] Peak heat release rate: 97.1 kW / m 2

[0085] Peak smoke release rate: 0.0162 m 2 / s

[0086] Flame-retardant reconstituted decorative lateral curvature: 0.086%

[0087] Number of visible adhesive residues per square meter (tested according to GB / T 28998-2012 method): 0

[0088] A control experiment was conducted based on Example 3, and the following comparative examples were obtained.

[0089] Comparative Example 1:

[0090] The difference between Comparative Example 1 and Example 3 is that:

[0091] (1) Inorganic filler adhesives are not used; instead, they are replaced with melamine-modified urea-formaldehyde resin of the same origin.

[0092] (2) No cyclodextrin is added in the preparation of flame retardant adhesives.

[0093] performance:

[0094] Peak heat release rate: 154.1 kW / m 2

[0095] Peak smoke release rate: 0.0292 m 2 / s

[0096] Flame-retardant reconstituted decorative lateral curvature: 1.116%

[0097] Number of visible adhesive residues per square meter (tested according to GB / T 28998-2012 method): 0

[0098] Comparative Example 2:

[0099] The difference between Comparative Example 2 and Example 3 is that:

[0100] No cyclodextrin is added during the preparation of flame-retardant adhesives.

[0101] performance:

[0102] Peak heat release rate: 141.9 kW / m 2

[0103] Peak smoke emission rate: 0.0211 m 2 / s

[0104] Flame-retardant reconstituted decorative lateral curvature: 1.006%

[0105] Number of visible adhesive residues per square meter (tested according to GB / T 28998-2012 method): 0

[0106] Comparative Example 3:

[0107] The difference between Comparative Example 3 and Example 3 is that:

[0108] Instead of using inorganic filler adhesives, melamine-modified urea-formaldehyde resin of the same origin is used.

[0109] performance:

[0110] Peak heat release rate: 149.1 kW / m 2

[0111] Peak smoke release rate: 0.0251 m 2 / s

[0112] Flame-retardant reconstituted decorative lateral curvature: 1.102%

[0113] Number of visible adhesive residues per square meter (tested according to GB / T 28998-2012 method): 5

[0114] Comparative Example 4:

[0115] The difference between Comparative Example 4 and Example 3 is that:

[0116] In the preparation of flame-retardant adhesives, cyclodextrin is added in a blending form without reacting, i.e.:

[0117] A 37% formaldehyde aqueous solution was added to a reaction vessel, followed by the addition of urea (molar ratio of formaldehyde to urea of ​​0.93:1), melamine (60% of the formaldehyde solution mass), and cyclodextrin (40% of the formaldehyde solution mass) to obtain a blended flame-retardant adhesive.

[0118] performance:

[0119] Peak heat release rate: 131.1 kW / m 2

[0120] Peak smoke release rate: 0.0212 m 2 / s

[0121] Flame-retardant reconstituted decorative lateral curvature: 1.112%

[0122] The number of visible glue residues per square meter (tested according to GB / T 28998-2012 method): 7.

Claims

1. A method for preparing a flame-retardant reconstituted decorative material, characterized in that, include: (1): Prepare inorganic filler adhesive and flame retardant adhesive, wherein, (1-1) Inorganic filler adhesives are prepared by the following method: Nano-montmorillonite and nano-hydrotalcite are mixed evenly at a mass ratio of 1:1-1.5 and added to melamine-modified urea-formaldehyde resin with a melamine content of 8-11% and a solid content of 50-55% at a mass ratio of 25-30:

100. After stirring at room temperature for 5-8 hours, an inorganic filler adhesive is obtained. (1-2) The flame-retardant adhesive is prepared by the following method: A 37-40% formaldehyde aqueous solution was added to the reaction vessel, and a certain amount of NaOH solution was added to adjust the pH value to 8.4-8.

6. Then, the first batch of urea, the first batch of melamine, and cyclodextrin were added. The temperature was raised to 70-80℃ and maintained for 1-2.5 hours. The molar ratio of formaldehyde to the first batch of urea was 0.9-0.96:0.45-0.

55. Melamine accounted for 25-35% of the mass of the formaldehyde solution, and cyclodextrin accounted for 30-55% of the mass of the formaldehyde solution. Then add the second batch of urea and the second batch of melamine, adjust the pH value to 6.5-6.7 with formic acid solution, and continue to maintain the temperature at 70-80℃ for 1-2.5h. Then adjust the pH value to 8.5-8.7 with a certain amount of NaOH solution. The molar ratio of formaldehyde and the second batch of urea is 0.9-0.96:0.45-0.55, and the second batch of melamine accounts for 8-12% of the mass of the formaldehyde solution. Stop heating and wait for the temperature to drop to room temperature to obtain the flame retardant adhesive. (2): Preparation of flame-retardant reconstituted decorative materials: (2-1) Apply inorganic filler adhesive to the surface of wood veneer of a certain or different thickness, with an adhesive application rate of 110-125 g / m². 2 After the glued veneer sheets are assembled, they are cold-pressed at a pressure of 0.20-0.25 MPa for 168-180 hours to obtain the first set of timber. (2-2) The first group of timber is planed along any side into reconstituted veneers of a certain or different thickness. Then, flame-retardant adhesive is applied to the surface of each reconstituted veneer at a rate of 110-125 g / m². 2 After the glued veneer sheets are assembled, they are cold-pressed at a pressure of 0.20-0.25 MPa for 168-180 hours to obtain the second set of timber. (2-3) The second group of timber is planed along any side into veneers with a thickness of 0.40-0.60mm to obtain flame-retardant reconstituted decorative material.

2. The preparation method according to claim 1, wherein, In (1-1), the average particle size of nano-montmorillonite is 50-70 nm, and the average particle size of nano-hydrotalcite is 50-70 nm.

3. The preparation method according to claim 1, wherein, In (2-1), the wood veneer is any one or a combination of poplar, eucalyptus, and pine, with a thickness of 1.7-1.8 mm and a moisture content of 8-10%.

4. The preparation method according to claim 3, wherein, In step (2-1), the glued wood veneer is assembled to a thickness of 1.2-1.5m.

5. The preparation method according to claim 4, wherein, In step (2-2), the first group of timber is planed into reconstituted veneers with a thickness of 1.0-1.2 mm.

6. The preparation method according to claim 5, wherein, In step (2-2), the glued reconstituted veneer blanks are assembled to a thickness of 1.2-1.5 μm.

7. The preparation method according to claim 1, wherein, As described in (2-1), the blanks are assembled along the wood grain direction. The blanks are assembled along the layering direction in (2-2).

8. The preparation method according to claim 7, wherein, The (2-3) section is cut along the side of the grid.

9. A flame-retardant reconstituted decorative material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.