Antibacterial and Flame-Retardant Ultra-Thin Fiberboard and Its Preparation Method

Abstract

Provided is an antibacterial and flame-retardant ultra-thin fiberboard and its preparation method, which can obtain good antibacterial and flame-retardant properties and adapt to the high-temperature hot pressing of ultra-thin fiberboard without affecting the curing process of the adhesive. The preparation method includes: adding NP-S-P solution to the urea-formaldehyde resin adhesive, fully stirring and then adding an aqueous NaOH solution to adjust the pH value to obtain antibacterial and flame-retardant adhesive 1; continuing to add modified porphyrin-type cobalt antibacterial agent N-Co to antibacterial and flame-retardant adhesive 1 and blending evenly to obtain antibacterial and flame-retardant adhesive 2; blending wood fibers and antibacterial and flame-retardant adhesive 2 evenly in a glue mixer, and drying the wood fibers after gluing to obtain a paving material with a moisture content of 6.0-6.5%; paving the paving material into a continuous slab belt, setting the target board thickness to 1.2 mm, and the fiberboard density to 800 Kg / m 3 , and sending the slab belt to a hot press for hot pressing.

Description

Technical Field

[0001] The present invention belongs to the field of antibacterial of wood materials, and particularly relates to an antibacterial and flame-retardant ultra-thin fiberboard and a preparation method thereof. Background Art

[0002] As a new variety in the field of fiberboards, the ultra-thin fiberboard expands and extends the uses of high-density ultra-thin fiberboards, replacing most of the uses of cardboard with relatively large pollution and high production costs, and has broad prospects. In particular, at present, as a surface layer material used in decorative boards, the improvement of antibacterial properties is crucial.

[0003] Antibacterial is a major direction in the research field of household materials. Controlling and eliminating the growth and reproduction of pathogenic microorganisms and producing environmentally friendly antibacterial artificial boards to create a healthy and comfortable living environment for humans is an important topic in the artificial board industry.

[0004] At present, salicylanilide, carbendazim, bacteriostatic clear, boric acid, etc. are mostly selected as antibacterial agents for the antibacterial treatment of artificial boards. Their antibacterial effects are acceptable, but they have a greater impact on the bonding strength of the boards and there is also secondary pollution.

[0005] Most of the decorative materials such as interior decoration of buildings, furniture and other interior ornaments use wood materials. Wood materials are flammable, bringing potential fire hazards to people. Therefore, enhancing the material's own ability to resist combustion and prevent combustion has become an issue that people are increasingly concerned about. Among various types of flame-retardant resins, the flame-retardant effect of flame-retardant resins and their impact on the bonding strength cannot be ignored. Summary of the Invention

[0006] The present invention is developed in view of the above technical problems, and aims to provide an antibacterial and flame-retardant ultra-thin fiberboard that can obtain good antibacterial and flame-retardant properties, adapt to high-temperature hot pressing and does not affect the curing of adhesives, and a preparation method thereof.

[0007] Phosphorus-based oxazolidinone and sodium aminosulfonate with a molar ratio of 1:(0.5 - 1) are added to a heatable container containing an appropriate amount of water-hydrochloric acid mixture. The water-hydrochloric acid mixture is composed of water and hydrochloric acid with a mass ratio of 1:(1.2 - 1.5) and a mass percentage concentration of 37%. Stir and react at 60 - 80 °C for 3 - 6 h, and then continue to stir while naturally cooling to 25 - 28 °C to obtain reaction solution 1 containing the reaction product NP-S, where the molecular formula of NP-S is:

[0008]

[0009] The reaction solution 1 is further added with a phosphaphenanthrene compound derivative DOPO-COOH in a molar ratio of (1-2.5):1 to the phosphorus-based oxazolidinone, and the mixture is stirred at 89-95° C. for 10-17 hours, and then the mixture is naturally cooled to 25-28° C. while continuing to stir, to obtain a reaction solution 2 containing a reaction product NP-SP, wherein the molecular formula of NP-SP is:

[0010]

[0011] The reaction liquid 2 is added to the urea-formaldehyde resin adhesive with a solid content of 50-60%, wherein the mass ratio of the urea-formaldehyde resin adhesive to the reaction liquid 2 is 1:(0.7-1.1), and after sufficient stirring, a NaOH aqueous solution is added to adjust the pH value to 7.0-7.2 to obtain the antibacterial flame retardant adhesive 1.

[0012] Sodium tetraoxalate modified porphyrin type cobalt antibacterial agent N-Co is further added to the antibacterial flame retardant adhesive 1, wherein the mass ratio of the antibacterial flame retardant adhesive 1 to N-Co is 100:(10-14), and the mixture is evenly blended to obtain the antibacterial flame retardant adhesive 2, wherein the molecular formula of N-Co is:

[0013]

[0014] 50-100 mesh wood fibers with a moisture content of 3-3.5% and antibacterial flame retardant adhesive 2 with a weight of 10-15% of the wood fiber are mixed evenly in a glue mixer, and the mixed wood fibers are dried to obtain a paving material with a moisture content of 6.0-6.5%. The drying process is performed at a temperature of 50-70°C.

[0015] The paving material is laid into a continuous slab strip, and the target slab thickness is set to 1.2mm and the fiberboard density is 800Kg / m 3 The slab strip is sent to the hot press for hot pressing. The hot press is arranged with two continuous pressure zones according to the forward direction of the slab strip. The hot pressing temperature of zone 1 is 150-170℃, the pressure is 35bar-50bar, and the hot pressing speed is 50m / min. The hot pressing temperature of zone 2 is 130-140℃, the hot pressing speed is 300m / min, and the pressure is 120bar-150bar.

[0016] The method further includes: steaming the qualified wood chips at a pressure of 7.5 bar to 8.0 bar, a temperature of 160° C. to 165° C., and a time of 3.5 min to 4.0 min, adding melted 58# fully refined paraffin wax to the steamed wood chips and performing heat grinding to obtain 50-100 mesh wood fibers.

[0017] The preparation method of N-Co is as follows: Porphyrin cobalt and sodium ethylenediaminetetraacetate with a molar ratio of 1:1 are placed in a heatable container, and an appropriate amount of water-ethanol mixture is added and stirred evenly. The mass ratio of water to ethanol is 10:(1-1.5); The temperature is raised to 80-110°C at a heating rate of 8-10°C / min and reacted for 12-14h. After the reaction, it is cooled to room temperature, then an appropriate amount of water is added, and after filtration and drying, white powder of N-Co is obtained.

[0018] According to the present invention, durable antibacterial is achieved by thermal polymerization during the hot pressing process, and by controlling the drying treatment, it is beneficial to expose the functional groups of urea-formaldehyde resin. The urea-formaldehyde resin can complex and adsorb with the Na groups on the antibacterial agents N-Co and NP-S-P, which is presumably a factor ensuring the mechanical strength of the fiberboard. The access of the flame retardant component phosphorus-based oxazolidinone and its relatively stable retention by the adhesive through complexation adsorption with the Na group are not easily lost, and no obvious influence on the mechanical properties is observed. On the other hand, the adhesive complexes with the Na group end of the antibacterial agent, ensuring the freedom of the functional end of the antibacterial agent. The longer chain structure of the free end of NP-S-P and the repulsion between the amino group on N-Co and the amino group of the adhesive are both beneficial to the exertion of the free end function. And NP-S-P inhibits bacteria by inhibiting protein synthesis, and cooperates synergistically with the metal antibacterial effect of N-Co. It is speculated that the favorable space of the free end contributes to the synergistic cooperation. Detailed implementation mode

[0019] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. The described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In the implementation mode, without special declaration, the numerical range "A~B" means above A (greater than or equal to A) and below B (less than or equal to B). When referring to normal temperature or room temperature, it usually means between 22~25°C, and sometimes between 20~28°C according to different processes. When there is no temperature limit for some processes, it is generally considered to be carried out at the normal temperature or room temperature.

[0021] The ultra-thin high density fiberboard defined by GB / T18259-2009 and LY / T1717-2007 is applicable to the present invention: The ultra-thin high density fiberboard is made from wood or other plants as raw materials, through fiber preparation, applying synthetic resin, and under the conditions of heating and pressing, it is pressed into a board with a thickness not greater than 1.5mm and a nominal density not less than 0.8g / cm 3 of the board.

[0022] The present invention aims to contribute to the research on the antibacterial function and flame retardancy of ultra-thin high-density fiberboard, and the specific proposal is as follows.

[0023] Add water with a mass ratio of 1:(1.2 - 1.5) and hydrochloric acid with a mass percentage concentration of 37% into a heatable container, and then add phosphonic oxazolidinone and sodium aminosulfonate with a molar ratio of 1:(0.5 - 1). Stir and react at 60 - 80 °C for 3 - 6 h, then continue to stir while naturally cooling to 25 - 28 °C. Preferably, stir and react at 70 - 80 °C for 5 - 6 h, then continue to stir while naturally cooling to 27 - 28 °C. According to this process, reaction solution 1 containing the reaction product NP-S is obtained, where the molecular formula of NP-S is:

[0024]

[0025] NP-S is formed by the reaction of phosphonic oxazolidinone and sodium aminosulfonate. The molecular formula of phosphonic oxazolidinone is as follows:

[0026]

[0027] The reaction equation of the above process is:

[0028]

[0029] Continue to add a phosphaphenanthrene compound derivative DOPO-COOH with a molar ratio of (1 - 2.5):1 to the added amount of phosphonic oxazolidinone to reaction solution 1. Stir and react at 89 - 95 °C for 10 - 17 h, then continue to stir while naturally cooling to 25 - 28 °C. Preferably, stir and react at 90 - 92 °C for 12 - 17 h, then continue to stir while naturally cooling to 27 - 28 °C to obtain reaction solution 2 containing the reaction product NP-S-P. The molecular formula of NP-S-P is:

[0030]

[0031] In the above preparation, NP-S-P is formed by the reaction of DOPO-COOH and NP-S. The molecular formula of DOPO-COOH is:

[0032]

[0033] The reaction equation of the above reaction is:

[0034]

[0035] Add reaction solution 2 to the urea-formaldehyde resin adhesive with a solid content of 50-60%, where the mass ratio of the urea-formaldehyde resin adhesive to reaction solution 2 is 1:(0.7-1.1), and the preferred mass ratio is 1:(0.7-0.9). After sufficient stirring, add an aqueous NaOH solution to adjust the pH value to 7.0-7.2. The concentration of the aqueous NaOH solution can be, for example, 1-3 mol / L. Antibacterial and flame-retardant adhesive 1 is obtained according to this process.

[0036] Continue to add sodium ethylenediaminetetraacetate modified porphyrin cobalt antibacterial agent N-Co to antibacterial and flame-retardant adhesive 1, where the mass ratio of antibacterial and flame-retardant adhesive 1 to N-Co is 100:(10-14), and the preferred mass ratio is 100:(10-12). Blend evenly, and antibacterial and flame-retardant adhesive 2 is obtained according to this process.

[0037] The molecular formula of N-Co is:

[0038]

[0039] N-Co is prepared by the following method:

[0040] Place porphyrin cobalt and sodium ethylenediaminetetraacetate with a molar ratio of 1:1 in a heatable container, add an appropriate amount of water-ethanol mixture and stir evenly. The mass ratio of water to ethanol is 10:(1-1.5); heat to 80-110°C at a heating rate of 8-10°C / min and react for 12-14 h. After the reaction is completed, cool to room temperature, then add an appropriate amount of water, filter and dry to obtain white powder N-Co. Specific preparation examples of N-Co are provided here.

[0041] Preparation Example 1

[0042] Place 1 mmol of porphyrin cobalt and 1 mmol of sodium ethylenediaminetetraacetate in a 1000 mL heatable container, add 500 mL of water-ethanol mixture and stir evenly. The mixing ratio of water to ethanol is 10:1. Heat to 110°C at a heating rate of 10°C / min and react for 12 h. After the reaction is completed, cool to room temperature, then add 100 ml of water to the reaction solution, filter and dry to obtain white powder.

[0043] Preparation Example 2

[0044] Place 1 mmol of porphyrin cobalt and 1 mmol of sodium ethylenediaminetetraacetate in a 1000 mL heatable container, add 500 mL of water-ethanol mixture and stir evenly. The mixing ratio of water to ethanol is 10:1.5. Heat to 80°C at a heating rate of 8°C / min and react for 14 h. After the reaction is completed, cool to room temperature, then add 100 ml of water to the reaction solution, filter and dry to obtain white powder.

[0045] In the above preparation, N-Co is formed by the reaction of porphyrin-type cobalt and sodium ethylenediaminetetraacetate. The molecular formula of porphyrin-type cobalt is as follows:

[0046]

[0047] The reaction equation for the above reaction is:

[0048]

[0049] Wood fibers with a particle size of 50-100 mesh and a moisture content of 3-3.5% and 10-15% of the mass of the wood fibers of the antibacterial and flame-retardant adhesive 2 are uniformly blended in a glue mixer, and the blended wood fibers are dried to obtain a paving material with a moisture content of 6.0-6.5%.

[0050] The 50-100 mesh wood fibers can be prepared by washing logs with water and mechanical cutting, and preferably by steaming and refining. Steaming can soften the wood, swelling the amorphous region of cellulose, hemicellulose and lignin with water, providing free volume space for the intense movement of molecules. After the wood is hydrothermally treated, part of the hemicellulose is easily decomposed and dissolved into a liquid state. The free hydroxyl groups on the molecular chains in the amorphous region of cellulose adsorb water, thickening the water film in the cellulose gap, increasing the intermolecular distance and reducing the attraction, making it easy to produce relative sliding under the action of external force. As an example, the qualified wood chips are steamed at a steaming pressure of 7.5-8.0 bar, a steaming temperature of 160-165 °C, and a steaming time of 3.5-4.0 min. The steamed wood chips are sent into a refining mill, and the melted grinding aid is added thereto. As an example, the grinding aid is 58# fully refined paraffin wax, and the addition amount is controlled at 8-10 kg / m 3 The qualified wood chips are 5-8 cm in length, 5-8 cm in width, 1-2 cm in thickness, and have a moisture content of 55-65%. The preparation of the qualified wood chips includes washing with water and dehydration, and controlling the moisture content of the wood chips to be 55-65%. The preparation of the qualified wood chips also includes preheating the washed wood chips, controlling the preheating temperature at 90-98 °C. The preparation of the qualified wood chips also includes forming a wood plug by variable-diameter screw extrusion of the preheated wood chips. The following provides an example of the preparation of wood fibers.

[0051] Preparation Example 3

[0052] The New Zealand radiata pine log materials are sliced by a flaker. After slicing, the length and width dimensions of the wood chips range from 5 to 8 cm, and the thickness ranges from 1 to 2 cm. The sliced wood chips are washed and dehydrated, then enter the preheating buffer bin before the refiner through a sealed conveyor belt for temporary storage. After being extruded by a variable-diameter screw, they form a wood plug and are sent into a vertical digester for cooking and softening treatment. The cooking pressure is 7.5 bar, the cooking temperature is 162 °C, and the cooking treatment time is 3.5 min. The cooked wood chips are sent into the refiner for refining, and melted No. 58 fully refined paraffin is added to them, with an addition amount of 8 kg / m 3 , and pine fibers with a mesh size of 50 - 100 are obtained. The qualified fibers enter the drying pipeline, and the pipeline temperature is controlled at 60 °C, and the fiber moisture content is 3%.

[0053] Preparation Example 4

[0054] The New Zealand radiata pine log materials are sliced by a flaker. After slicing, the length and width dimensions of the wood chips range from 5 to 8 cm, and the thickness ranges from 1 to 2 cm. The sliced wood chips are washed and dehydrated, then enter the preheating buffer bin before the refiner through a sealed conveyor belt for temporary storage. After being extruded by a variable-diameter screw, they form a wood plug and are sent into a vertical digester for cooking and softening treatment. The cooking pressure is 8 bar, the cooking temperature is 164 °C, and the cooking treatment time is 4 min. The cooked wood chips are sent into the refiner for refining, and melted No. 58 fully refined paraffin is added to them, with an addition amount of 10 kg / m 3 , and pine fibers with a mesh size of 50 - 100 are obtained. The qualified fibers enter the drying pipeline, and the pipeline temperature is controlled at 70 °C, and the fiber moisture content is 3.5%.

[0055] The wood fibers after sizing are dried to obtain a matting material with a moisture content of 6.0 - 6.5%. The drying treatment is preferably carried out at a temperature of 50 - 70 °C. The matting material is formed into a continuous slab belt, and the target board thickness is set at 1.2 mm, and the fiberboard density is 800 Kg / m 3 , and the slab belt is sent to a hot press for hot pressing. The hot press is arranged with 2 consecutive pressure zones along the advancing direction of the slab belt. Among them, the hot pressing temperature in Zone 1 is 150 - 170 °C, the pressure is 35 bar - 50 bar, the hot pressing speed is 50 m / min, the hot pressing temperature in Zone 2 is 130 - 140 °C, the hot pressing speed is 300 m / min, and the pressure is 120 bar - 150 bar.

[0056] Specifically, the following are the preparation examples and comparative examples of the antibacterial ultra-thin fiberboard.

[0057] Example 1

[0058] Add 150 g of 37% concentrated hydrochloric acid to a reaction kettle containing 1000 mL of water, then add 1 mmol of phosphorous-based oxazolidinone and 0.5 mmol of sodium sulfamate, stir and react at 70 °C for 5 h, and then naturally cool to 27 °C during stirring to obtain the NP-S reaction solution. Continue to add 1 mmol of the phosphaphenanthrene compound derivative DOPO-COOH to the reaction solution 1, stir and react at 90 °C for 12 h, and then naturally cool to 25 °C during stirring to obtain the NP-S-P reaction solution. Add 90 g of the NP-S-P reaction solution to 100 g of the urea-formaldehyde resin adhesive with a solid content of 50%, fully stir, and then add an aqueous NaOH solution to adjust the pH to 7.0 to prepare adhesive 1. Weigh 100 g of adhesive 1 again and add 10 g of the ethylene diamine tetraacetate modified porphyrin-type cobalt antibacterial agent N-Co, and mix well to obtain adhesive 2. Mix 50-100 mesh wood fibers with a moisture content of 3% and 10% of the mass of the wood fibers of adhesive 2 evenly in a glue mixer, and dry the mixed wood fibers to obtain a paving material with a moisture content of 6.0%. Pave the paving material into a continuous slab belt, set the target board thickness to 1.2 mm, and the fiberboard density to 800 Kg / m 3 , send the slab belt to a hot press for hot pressing. The hot press is arranged with 2 consecutive pressure zones in the advancing direction of the slab belt. Among them, the hot pressing temperature in zone 1 is 150 °C, the pressure is 50 bar, the hot pressing speed is 50 m / min, the hot pressing temperature in zone 2 is 130 °C, the hot pressing speed is 300 m / min, and the pressure is 120 bar. The hot-pressed board is transferred to a turning frame through a conveyor belt for cooling, and then stacked and packed.

[0059] Example 2

[0060] Add 120 g of 37% concentrated hydrochloric acid to a reaction kettle containing 1000 mL of water, then add 1 mmol of phosphorous-based oxazolidinone and 0.5 mmol of sodium sulfamate, and stir and react at 80 °C for 6 h. Then, naturally cool to 28 °C during stirring to obtain the NP-S reaction solution. Continue to add 2.5 mmol of the phosphaphenanthrene compound derivative DOPO-COOH to the reaction solution 1, stir and react at 92 °C for 17 h, and then naturally cool to 28 °C during stirring to obtain the NP-S-P reaction solution. Add 110 g of the NP-S-P reaction solution to 100 g of urea-formaldehyde resin adhesive with a solid content of 50%, stir well, and then add an aqueous NaOH solution to adjust the pH to 7.2 to prepare adhesive 1. Weigh 100 g of adhesive 1 again and add 15 g of the oxalic acid tetraethylenediamine sodium modified porphyrin-type cobalt antibacterial agent N-Co, and mix well to obtain adhesive 2. Blend 50-100 mesh wood fibers with a moisture content of 3.5% and 10% of the mass of the wood fibers of adhesive 2 evenly in a glue mixer, and dry the glued wood fibers to obtain a paving material with a moisture content of 6.5%. Pave the paving material into a continuous slab belt, set the target board thickness to 1.2 mm, and the fiberboard density to 800 Kg / m 3 , and send the slab belt to a hot press for hot pressing. The hot press is arranged with 2 continuous pressure zones in the advancing direction of the slab belt. Among them, the hot pressing temperature in zone 1 is 170 °C, the pressure is 35 bar, the hot pressing speed is 50 m / min, the hot pressing temperature in zone 2 is 140 °C, the hot pressing speed is 300 m / min, and the pressure is 150 bar. The hot-pressed board is transferred to a turning frame through a conveyor belt for cooling, and then stacked and packaged.

[0061] Example 3

[0062] Add 135 g of 37% concentrated hydrochloric acid to a reaction kettle containing 1000 mL of water, then add 1 mmol of phosphorous-based oxazolidinone and 0.5 mmol of sodium sulfamate, stir and react at 60 °C for 3 h, and then naturally cool to 25 °C during stirring to obtain an NP-S reaction solution. Continue to add 1.5 mmol of phosphaphenanthrene compound derivative DOPO-COOH to the reaction solution 1, stir and react at 89 °C for 10 h, and then naturally cool to 25 °C during stirring to obtain an NP-S-P reaction solution. Add 70 g of the NP-S-P reaction solution to 100 g of urea-formaldehyde resin adhesive with a solid content of 50%, stir well, and then add an aqueous NaOH solution to adjust the pH to 7.0 to prepare adhesive 1. Weigh 100 g of adhesive 1 again and add 12 g of the modified porphyrin-type cobalt antibacterial agent N-Co of sodium ethylenediaminetetraacetate oxalate, and mix well to obtain adhesive 2. Mix 50-100 mesh wood fibers with a moisture content of 3.5% and 10% of the mass of the wood fibers of adhesive 2 evenly in a glue mixer, and dry the mixed wood fibers to obtain a paving material with a moisture content of 6.5%. Pave the paving material into a continuous slab belt, set the target board thickness to 1.2 mm, and the fiberboard density to 800 Kg / m 3 , and send the slab belt to a hot press for hot pressing. The hot press is arranged with 2 continuous pressure zones in the advancing direction of the slab belt. Among them, the hot pressing temperature in zone 1 is 150 °C, the pressure is 40 bar, the hot pressing speed is 50 m / min, the hot pressing temperature in zone 2 is 140 °C, the hot pressing speed is 300 m / min, and the pressure is 120 bar. The hot-pressed board is transferred to a turning frame through a conveyor belt for cooling, and then stacked and packed.

[0063] Comparative Example 1

[0064] Comparative Example 1 is designed with reference to Example 3. The difference is that after obtaining the NP-S reaction solution, the phosphaphenanthrene compound derivative DOPO-COOH is not added continuously, and 7 g of the NP-S reaction solution is directly added to the urea-formaldehyde resin adhesive.

[0065] Comparative Example 2

[0066] Comparative Example 1 is designed with reference to Example 3. The difference is that the mixed wood fibers are not dried, and the moisture content of the mixed wood fibers is measured to be 12%.

[0067] Comparative Example 3

[0068] Comparative Example 1 is designed with reference to Example 1. The difference is that 90 g of the NP-S reaction solution is added to 100 g of the urea-formaldehyde resin adhesive; the adhesive 1 is directly applied to the wood fibers without adding N-Co.

[0069] Antibacterial tests and mechanical property tests were carried out on the fiberboards obtained in each example and comparative example, and the results are shown in the following table.

[0070] Table 1:

[0071]

[0072] According to the test results, for Comparative Example 1 where the moisture content was not controlled after sizing, both the antibacterial property and the mechanical properties decreased. To a certain extent, reducing the moisture content was beneficial to the exposure of the functional groups of urea-formaldehyde resin. Urea-formaldehyde resin could complex and adsorb with the Na groups on the antibacterial agents N-Co and NP-S. It was speculated that this was a factor that did not affect the mechanical strength of the fiberboard, and the incorporation of the flame retardant component phosphazolidone did not significantly affect the mechanical properties. On the other hand, the adhesive complexed with the Na end of the antibacterial agent, ensuring the freedom of the functional end of the antibacterial agent. Moreover, the longer chain structure of the free end of NP-S and the repulsion between the amino groups on N-Co and the amino groups of the adhesive were both beneficial to the exertion of the function of the free end. And NP-S-P inhibited bacteria by inhibiting protein synthesis and synergistically cooperated with the metal antibacterial effect of N-Co. It was speculated that the favorable space at the free end contributed to the synergistic cooperation.

Claims

1. A preparation method of an antibacterial and flame-retardant ultra-thin fiberboard, characterized in that, it includes: Adding phosphazene oxazolidinone and sodium aminosulfonate with a molar ratio of 1:(0.5 - 1) into a heatable container filled with an appropriate amount of water-hydrochloric acid mixture, stirring and reacting at 60 - 80 °C for 3 - 6 h, then continuing to stir while naturally cooling to 25 - 28 °C to obtain reaction solution 1 containing the reaction product NP-S, where the molecular formula of NP-S is: Continuing to add a phosphaphenanthrene compound derivative DOPO-COOH with a molar ratio of (1 - 2.5):1 to the addition amount of phosphazene oxazolidinone in reaction solution 1, stirring and reacting at 89 - 95 °C for 10 - 17 h, then continuing to stir while naturally cooling to 25 - 28 °C to obtain reaction solution 2 containing the reaction product NP-S-P, where the molecular formula of NP-S-P is: Adding reaction solution 2 to an urea-formaldehyde resin adhesive with a solid content of 50 - 60%, where the mass ratio of the urea-formaldehyde resin adhesive to reaction solution 2 is 1:(0.7 - 1.1), fully stirring and then adding an NaOH aqueous solution to adjust the pH value to 7.0 - 7.2 to obtain antibacterial and flame-retardant adhesive 1; Continuing to add sodium ethylenediaminetetraacetate modified porphyrin-type cobalt antibacterial agent N-Co to antibacterial and flame-retardant adhesive 1, where the mass ratio of antibacterial and flame-retardant adhesive 1 to N-Co is 100:(10 - 15), blending evenly to obtain antibacterial and flame-retardant adhesive 2, where the molecular formula of N-Co is: Blending 50 - 100 mesh wood fibers with a moisture content of 3 - 3.5% and 10 - 15% of antibacterial and flame-retardant adhesive 2 based on the mass of the wood fibers evenly in a glue mixer, and drying the glued wood fibers to obtain a paving material with a moisture content of 6.0 - 6.5%; Pave the paving material into a continuous slab strip, set the target board thickness to 1.2 mm, and the fiberboard density to 800 Kg / m 3 , send the slab strip to a hot press for hot pressing. The hot press is arranged with 2 continuous pressure zones in the advancing direction of the slab strip. Among them, the hot pressing temperature in Zone 1 is 150 - 170 °C, the pressure is 35 bar - 50 bar, the hot pressing speed is 50 m / min, the hot pressing temperature in Zone 2 is 130 - 140 °C, the hot pressing speed is 300 m / min, and the pressure is 120 bar - 150 bar.

2. The preparation method according to claim 1, wherein, The water-hydrochloric acid mixture is composed of water and hydrochloric acid with a mass percentage concentration of 37% in a mass ratio of 1:(1.2 - 1.5).

3. The preparation method according to claim 1, wherein, The drying treatment is carried out at a temperature of 50 - 70 °C.

4. The preparation method according to claim 1, further including: Steaming qualified wood chips, with a steaming pressure of 7.5 bar - 8.0 bar, a steaming temperature of 160 °C - 165 °C, and a steaming time of 3.5 min - 4.0 min, adding melted 58# fully refined paraffin to the steamed wood chips and performing hot grinding to obtain 50 - 100 mesh wood fibers.

5. The preparation method according to claim 1, wherein, N-Co is prepared by the following method: Placing porphyrin-type cobalt and sodium ethylenediaminetetraacetate with a molar ratio of 1:1 in a heatable container, adding an appropriate amount of water-ethanol mixture and stirring evenly, with a mass ratio of water to ethanol of 10:(1 - 1.5); heating to 80 - 110 °C at a heating rate of 8 - 10 °C / min and reacting for 12 - 14 h, cooling to room temperature after the reaction, then adding an appropriate amount of water, filtering and drying to obtain N-Co white powder.

6. An antibacterial and flame-retardant ultra-thin fiberboard, characterized in that, It is prepared by the preparation method according to any one of claims 1 - 5.

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