A high-strength flame-retardant and moisture-proof furniture board and its preparation method

Abstract

This invention discloses a high-strength, flame-retardant, and moisture-proof furniture board and its preparation method, relating to the field of furniture board technology. The board produced by this invention uses bamboo as raw material, which is processed into wood shavings. Urea-formaldehyde resin, nanocellulose made from waste materials during bamboo shavings processing, a waterproofing agent, and a flame retardant are added, and the board is then hot-pressed and laid together. Hydroxymethylated sodium lignosulfonate and melamine are added to the urea-formaldehyde resin to improve its performance. The board is laid by horizontally laying the core layer of wood shavings and vertically laying the surface layer of wood shavings, followed by a surface-core-surface layer arrangement to obtain a furniture board.

Description

Technical Field

[0001] This invention relates to the field of furniture board technology, specifically a high-strength, flame-retardant, and moisture-proof furniture board and its preparation method. Background Technology

[0002] With improved economic conditions, people's demands for living environments have gone beyond basic housing conditions, moving towards higher quality living and personalized living spaces. After purchasing a home, people often renovate to achieve their ideal living environment, making the choice of furniture materials crucial. Mainstream board products on the market include, but are not limited to, solid wood boards and engineered wood boards. Solid wood boards are made by directly sawing whole pieces of wood, possessing high natural beauty, but the reduction in raw materials and high cost deter most people. The emergence of engineered wood boards provides more options for whole-house decoration. According to 2024 China particleboard market research data, the demand for particleboard, one of the three major engineered wood products, continues to grow, showing strong production growth.

[0003] While particleboard has certain advantages in terms of price and plasticity, it has significant disadvantages in terms of load-bearing capacity, stability, and environmental friendliness. Particleboard was once "widely known" for its excessive formaldehyde levels, and there have been numerous cases of fires caused by its flammability resulting in serious casualties. Therefore, improving the raw material composition of particleboard for safe actual use is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength, flame-retardant, and moisture-proof furniture board and its preparation method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-strength flame-retardant and moisture-proof furniture board, comprising the following steps:

[0006] Step 1: Processing bamboo shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. Control the moisture content to 65-70% before shaving it. Then dry it to control the moisture content to 2-5%. Select the core layer shavings (50-120mm long, 20-50mm wide, and 0.3-0.8mm thick), the surface layer shavings (20-50mm long, 20-50mm wide, and 0.3-0.8mm thick), and any excess waste materials for later use.

[0007] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add sodium hydroxide solution to adjust the pH to 7.5-8.0. Heat to 40℃ and add the first batch of urea. Slowly heat to 90℃ within 30-40 minutes. Keep warm for 1 hour, then add sodium hydroxymethylated lignin sulfonate and stir evenly. Add formic acid solution dropwise to adjust the pH to 4.8-5.1. Keep warm for 1-2 hours, then immediately add sodium hydroxide solution dropwise to adjust the pH to 7.5-8.0. Add the second batch of urea and heat to 80-85℃. After reacting at ℃ for 30 min, add the third batch of urea, melamine, and glutaraldehyde, and react at 70-80℃ for 30 min. Adjust the pH to 7.5-8.0, cool to 40-50℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:(1.00-1.05):(0.02-0.05):(0.03-0.05). The amount of hydroxymethylated sodium lignin sulfonate added is 2-4 wt% of the modified urea-formaldehyde resin.

[0008] Step 3: Particleboard Preparation with Glue and Particleboard: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 5-10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.5-0.8MPa for 2-3 minutes, and then hot-press at 1.5-1.8MPa and 190-200℃ for 1-2 minutes. Cool to obtain the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0009] The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: dissolve sodium lignin sulfonate in water, add sodium hydroxide to adjust the pH to 11, slowly add formaldehyde solution, react at 90℃ for 2h, add formic acid to adjust the pH to 2, centrifuge and wash, and dry at 60℃ for 12h to obtain hydroxymethylated sodium lignin sulfonate.

[0010] The preparation steps of modified nanocellulose in step 3 are as follows: the excess waste material in step 1 is crushed, sieved through a 100-mesh bamboo powder, placed in deionized water, 2,2,6,6-tetramethylpiperidine oxide and sodium bromide are added, and a 3-5% sodium hypochlorite solution is added. The mixture is stirred for 3 hours, during which hydrochloric acid or alkaline solution is added dropwise to control the pH to 10-10.5. After the reaction is completed, anhydrous ethanol is added, the mixture is filtered and washed, dispersed in deionized water, mixed evenly with polyethyleneimine, heated to 100℃, stirred and reacted for 10 hours. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, the process is repeated 2-3 times, and the mixture is freeze-dried to obtain modified nanocellulose.

[0011] The preparation steps of the flame retardant in step 3 are as follows: place polyethyleneimine in anhydrous ethanol and stir to mix, add ammonium polyphosphate and stir for 2-3 hours, then heat to 60-70℃, filter and wash, and dry at 60℃ to obtain the flame retardant.

[0012] The preparation steps of the waterproofing agent are as follows: weigh paraffin wax, stearic acid and microcrystalline wax in a mass ratio of 1:1:1 and mix them, then melt them at 100°C.

[0013] The particleboard has a particleboard layer-core-core layer particleboard ... layer particleboard layer layer particleboard layer layer particleboard layer layer particleboard layer layer particleboard layer layer layer particleboard layer layer layer layer particleboard layer layer layer layer layer

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. The board produced by this invention uses oriented shavings of different sizes to comprehensively improve the mechanical properties of the board. The shavings are made from bamboo, resulting in a large raw material yield. The waste material left over from shavings processing is crushed to prepare nanocellulose, which is then added to the adhesive mixture to fill gaps and maximize the utilization rate of raw materials. This effectively improves the toughness of the glue-cured board. The nanocellulose is modified by introducing polyethyleneimine, which improves dispersion and enhances the bonding performance of the resin adhesive. The flame retardant is made by self-assembling and polymerizing ammonium polyphosphate and polyethyleneimine and adding it to the particleboard. The polyethyleneimine enhances the interfacial bonding between the flame retardant and the shavings, resulting in excellent flame retardant effect.

[0016] 2. The resin adhesive used in the boards produced by this invention contains a small amount of glutaraldehyde to replace part of the formaldehyde, thereby reducing the content of free formaldehyde in the resin adhesive. At the same time, hydroxymethylated lignin is added as a formaldehyde scavenger, which can react with free formaldehyde to effectively reduce the content of free formaldehyde and improve the thermal stability of the resin.

[0017] 3. The waterproofing agent uses a wax composite system, which improves the waterproofing performance of particleboard to a certain extent. Detailed Implementation

[0018] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the experiment, the formaldehyde solution concentration was 37%; the relative molecular weight of polyethyleneimine was 1800; and ammonium polyphosphate was purchased from Aladdin Biochemical Technology, catalog number A669915.

[0020] The preparation steps of the flame retardant are as follows: 10g of polyethyleneimine is placed in 300ml of anhydrous ethanol and stirred and mixed. 100g of ammonium polyphosphate is added and stirred for 2 hours. Then it is heated to 60℃, filtered and washed, and dried at 60℃ to obtain the flame retardant.

[0021] The preparation steps of the waterproofing agent are as follows: weigh paraffin wax, stearic acid and microcrystalline wax in a mass ratio of 1:1:1 and mix them, then melt them at 100°C.

[0022] The core layer of wood shavings is 60mm long, 20mm wide, and 0.8mm thick.

[0023] The surface wood shavings are 20mm long, 20mm wide, and 0.4mm thick.

[0024] Example 1: This example provides a high-strength flame-retardant and moisture-proof furniture board and its preparation method. The specific preparation steps are as follows:

[0025] Step 1: Processing wood shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. After controlling the moisture content to reach 65%, shavings are produced. Then, the bamboo is dried and the moisture content is controlled to drop to 3%. The core layer wood shavings, surface wood shavings, and excess waste are screened out and set aside.

[0026] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add 30% sodium hydroxide solution to adjust the pH to 8.0. Heat to 40℃ and add 35% of the total amount of urea. Slowly heat to 90℃ within 30℃ and maintain this temperature for 1 hour. Add hydroxymethylated sodium lignin sulfonate and stir evenly. Add 30% formic acid solution dropwise to adjust the pH to 5. Maintain this temperature for 90 minutes. Immediately add 30% sodium hydroxide solution dropwise to adjust the pH to 7.5. Add 33% of the total amount of urea. React at 85℃ for 30 minutes. Add 32% of the total amount of urea, melamine, and glutaraldehyde. React at 80℃ for 30 minutes. Adjust the pH to 7.5, cool to 40℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:1.03:0.02:0.03. The amount of hydroxymethylated sodium lignin sulfonate added is 2 wt% of the modified urea-formaldehyde resin adhesive.

[0027] Step 3: Particleboard Preparation: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.8MPa for 2 minutes, and then hot-press at 1.5MPa and 200℃ for 2 minutes to obtain the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0028] The particleboard has a particleboard layer-core-core layer particleboard mass ratio of 1:1:1; core layer adhesive application is 4% and surface layer adhesive application is 10%; flame retardant application is 6 wt% of particleboard; waterproofing agent application is 1 wt% of particleboard; and modified nanocellulose application is 1 wt%.

[0029] The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: Sodium lignin sulfonate is dissolved in water, the pH is adjusted to 11 with 30% sodium hydroxide, formaldehyde solution is slowly added dropwise, and the reaction is carried out at 90℃ for 2 hours. Then, 30% formic acid is added dropwise to adjust the pH to 2. After centrifugation and washing, the solution is dried at 60℃ for 12 hours to obtain hydroxymethylated sodium lignin sulfonate. The material ratio of sodium lignin sulfonate to formaldehyde solution is 3:1.

[0030] The preparation steps of modified nanocellulose are as follows: the excess waste material in step 1 is crushed and sieved through a 100-mesh bamboo powder. 1g of sieved bamboo powder is placed in 100ml of deionized water, 0.02g of 2,2,6,6-tetramethylpiperidine oxide and 0.1g of sodium bromide are added, and 60ml of 5% sodium hypochlorite solution is added. The mixture is stirred for 3h, during which hydrochloric acid or alkali solution is added dropwise to control the pH at 10. After the reaction is completed, 10ml of anhydrous ethanol is added sequentially, filtered and washed, and dispersed in deionized water to 1.5wt%. It is then mixed evenly with 100ml of polyethyleneimine, heated to 100℃, and stirred for 10h. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, and the process is repeated 3 times. The mixture is then freeze-dried to obtain modified nanocellulose.

[0031] Example 2: This example provides a high-strength flame-retardant and moisture-proof furniture board and its preparation method. The specific preparation steps are as follows:

[0032] Step 1: Processing wood shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. After controlling the moisture content to reach 65%, shavings are produced. Then, the bamboo is dried and the moisture content is controlled to drop to 3%. The core layer wood shavings, surface wood shavings, and excess waste are screened out and set aside.

[0033] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add 30% sodium hydroxide solution to adjust the pH to 8.0. Heat to 40℃ and add 35% of the total amount of urea. Slowly heat to 90℃ within 30℃ and maintain this temperature for 1 hour. Add hydroxymethylated sodium lignin sulfonate and stir evenly. Add 30% formic acid solution dropwise to adjust the pH to 5. Maintain this temperature for 90 minutes. Immediately add 30% sodium hydroxide solution dropwise to adjust the pH to 7.5. Add 33% of the total amount of urea. React at 85℃ for 30 minutes. Add 32% of the total amount of urea, melamine, and glutaraldehyde. React at 80℃ for 30 minutes. Adjust the pH to 7.5, cool to 40℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:1.01:0.04:0.04. The amount of hydroxymethylated sodium lignin sulfonate added is 3 wt% of the modified urea-formaldehyde resin adhesive.

[0034] Step 3: Particleboard Preparation: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.8MPa for 2 minutes, and then hot-press at 1.5MPa and 200℃ for 2 minutes to obtain the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0035] The particleboard has a particleboard layer-core-core layer particleboard ... layer particleboard layer layer particleboard layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer

[0036] The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: Sodium lignin sulfonate is dissolved in water, the pH is adjusted to 11 with 30% sodium hydroxide, formaldehyde solution is slowly added dropwise, and the reaction is carried out at 90℃ for 2 hours. Then, 30% formic acid is added dropwise to adjust the pH to 2. After centrifugation and washing, the solution is dried at 60℃ for 12 hours to obtain hydroxymethylated sodium lignin sulfonate. The material ratio of sodium lignin sulfonate to formaldehyde solution is 3:1.

[0037] The preparation steps of modified nanocellulose are as follows: the excess waste material in step 1 is crushed and sieved through a 100-mesh bamboo powder. 1g of sieved bamboo powder is placed in 100ml of deionized water, 0.02g of 2,2,6,6-tetramethylpiperidine oxide and 0.1g of sodium bromide are added, and 60ml of 5% sodium hypochlorite solution is added. The mixture is stirred for 3h, during which hydrochloric acid or alkali solution is added dropwise to control the pH at 10. After the reaction is completed, 10ml of anhydrous ethanol is added sequentially, filtered and washed, and dispersed in deionized water to 1.5wt%. It is then mixed evenly with 100ml of polyethyleneimine, heated to 100℃, and stirred for 10h. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, and the process is repeated 3 times. The mixture is then freeze-dried to obtain modified nanocellulose.

[0038] Example 3: This example provides a high-strength flame-retardant and moisture-proof furniture board and its preparation method. The specific preparation steps are as follows:

[0039] Step 1: Processing wood shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. After controlling the moisture content to reach 65%, shavings are produced. Then, the bamboo is dried and the moisture content is controlled to drop to 3%. The core layer wood shavings, surface wood shavings, and excess waste are screened out and set aside.

[0040] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add 30% sodium hydroxide solution to adjust the pH to 8.0. Heat to 40℃ and add 35% of the total amount of urea. Slowly heat to 90℃ within 30℃ and maintain this temperature for 1 hour. Add hydroxymethylated sodium lignin sulfonate and stir evenly. Add 30% formic acid solution dropwise to adjust the pH to 5. Maintain this temperature for 90 minutes. Immediately add 30% sodium hydroxide solution dropwise to adjust the pH to 7.5. Add 33% of the total amount of urea. React at 85℃ for 30 minutes. Add 32% of the total amount of urea, melamine, and glutaraldehyde. React at 80℃ for 30 minutes. Adjust the pH to 7.5, cool to 40℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:1.00:0.05:0.05. The amount of hydroxymethylated sodium lignin sulfonate added is 4 wt% of the modified urea-formaldehyde resin adhesive.

[0041] Step 3: Particleboard Preparation: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.8MPa for 2 minutes, and then hot-press at 1.5MPa and 200℃ for 2 minutes to obtain the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0042] The particleboard has a particleboard layer-core-core layer particleboard ... layer particleboard layer layer particleboard layer layer particleboard layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer

[0043] The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: Sodium lignin sulfonate is dissolved in water, the pH is adjusted to 11 with 30% sodium hydroxide, formaldehyde solution is slowly added dropwise, and the reaction is carried out at 90℃ for 2 hours. Then, 30% formic acid is added dropwise to adjust the pH to 2. After centrifugation and washing, the solution is dried at 60℃ for 12 hours to obtain hydroxymethylated sodium lignin sulfonate. The material ratio of sodium lignin sulfonate to formaldehyde solution is 3:1.

[0044] The preparation steps of modified nanocellulose are as follows: the excess waste material in step 1 is crushed and sieved through a 100-mesh bamboo powder. 1g of sieved bamboo powder is placed in 100ml of deionized water, 0.02g of 2,2,6,6-tetramethylpiperidine oxide and 0.1g of sodium bromide are added, and 60ml of 5% sodium hypochlorite solution is added. The mixture is stirred for 3h, during which hydrochloric acid or alkali solution is added dropwise to control the pH at 10. After the reaction is completed, 10ml of anhydrous ethanol is added sequentially, filtered and washed, and dispersed in deionized water to 1.5wt%. It is then mixed evenly with 100ml of polyethyleneimine, heated to 100℃, and stirred for 10h. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, and the process is repeated 3 times. The mixture is then freeze-dried to obtain modified nanocellulose.

[0045] Comparative Example 1: For Example 3, sodium hydroxymethyl lignin sulfonate was not added. The specific steps are as follows:

[0046] Step 1: Processing wood shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. After controlling the moisture content to reach 65%, shavings are produced. Then, the bamboo is dried and the moisture content is controlled to drop to 3%. The core layer wood shavings, surface wood shavings, and excess waste are screened out and set aside.

[0047] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add 30% sodium hydroxide solution to adjust the pH to 8.0. Heat to 40℃ and add 35% of the total amount of urea. Slowly heat to 90℃ within 30℃ and maintain this temperature for 1 hour. Add hydroxymethylated sodium lignin sulfonate and stir evenly. Add 30% formic acid solution dropwise to adjust the pH to 5. Maintain this temperature for 90 minutes. Immediately add 30% sodium hydroxide solution dropwise to adjust the pH to 7.5. Add 33% of the total amount of urea. React at 85℃ for 30 minutes. Add 32% of the total amount of urea, melamine, and glutaraldehyde. React at 80℃ for 30 minutes. Adjust the pH to 7.5, cool to 40℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:1.00:0.05:0.05. The amount of hydroxymethylated sodium lignin sulfonate added is 4 wt% of the modified urea-formaldehyde resin adhesive.

[0048] Step 3: Particleboard Preparation: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.8MPa for 2 minutes, and then hot-press at 1.5MPa and 200℃ for 2 minutes to obtain the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0049] The particleboard has a particleboard layer-core-core layer particleboard ... layer particleboard layer layer particleboard layer layer particleboard layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer layer

[0050] The preparation steps of modified nanocellulose are as follows: the excess waste material in step 1 is crushed and sieved through a 100-mesh bamboo powder. 1g of sieved bamboo powder is placed in 100ml of deionized water, 0.02g of 2,2,6,6-tetramethylpiperidine oxide and 0.1g of sodium bromide are added, and 60ml of 5% sodium hypochlorite solution is added. The mixture is stirred for 3h, during which hydrochloric acid or alkali solution is added dropwise to control the pH at 10. After the reaction is completed, 10ml of anhydrous ethanol is added sequentially, filtered and washed, and dispersed in deionized water to 1.5wt%. It is then mixed evenly with 100ml of polyethyleneimine, heated to 100℃, and stirred for 10h. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, and the process is repeated 3 times. The mixture is then freeze-dried to obtain modified nanocellulose.

[0051] Comparative Example 2: The nanocellulose of Example 3 was not modified, and the specific steps included the following:

[0052] Step 1: Processing wood shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. After controlling the moisture content to reach 65%, shavings are produced. Then, the bamboo is dried and the moisture content is controlled to drop to 3%. The core layer wood shavings, surface wood shavings, and excess waste are screened out and set aside.

[0053] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add 30% sodium hydroxide solution to adjust the pH to 8.0. Heat to 40℃ and add 35% of the total amount of urea. Slowly heat to 90℃ within 30℃ and maintain this temperature for 1 hour. Add hydroxymethylated sodium lignin sulfonate and stir evenly. Add 30% formic acid solution dropwise to adjust the pH to 5. Maintain this temperature for 90 minutes. Immediately add 30% sodium hydroxide solution dropwise to adjust the pH to 7.5. Add 33% of the total amount of urea. React at 85℃ for 30 minutes. Add 32% of the total amount of urea, melamine, and glutaraldehyde. React at 80℃ for 30 minutes. Adjust the pH to 7.5, cool to 40℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:1.00:0.05:0.05. The amount of hydroxymethylated sodium lignin sulfonate added is 4 wt% of the modified urea-formaldehyde resin adhesive.

[0054] Step 3: Particleboard Preparation: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.8MPa for 2 minutes, and then hot-press at 1.5MPa and 200℃ for 2 minutes to obtain the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0055] The particleboard has a particleboard layer-core-core layer particleboard ...

[0056] The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: Sodium lignin sulfonate is dissolved in water, the pH is adjusted to 11 with 30% sodium hydroxide, formaldehyde solution is slowly added dropwise, and the reaction is carried out at 90℃ for 2 hours. Then, 30% formic acid is added dropwise to adjust the pH to 2. After centrifugation and washing, the solution is dried at 60℃ for 12 hours to obtain hydroxymethylated sodium lignin sulfonate. The material ratio of sodium lignin sulfonate to formaldehyde solution is 3:1.

[0057] The preparation steps of nanocellulose are as follows: crush the excess waste material from step 1, sieve it through a 100-mesh bamboo powder, take 1g of sieved bamboo powder, place it in 100ml of deionized water, add 0.02g of 2,2,6,6-tetramethylpiperidine oxide and 0.1g of sodium bromide, add 60ml of 5% sodium hypochlorite solution, react under stirring for 3h, during which hydrochloric acid solution or alkaline solution is added dropwise to control the pH at 10, after the reaction is completed, add 10ml of anhydrous ethanol in sequence, filter and wash, and dry to obtain the nanocellulose.

[0058] Comparative Example 3, where the waterproofing agent in Example 3 was replaced with paraffin wax, was melted at 100°C. The specific steps are as follows:

[0059] Step 1: Processing wood shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. After controlling the moisture content to reach 65%, shavings are produced. Then, the bamboo is dried and the moisture content is controlled to drop to 3%. The core layer wood shavings, surface wood shavings, and excess waste are screened out and set aside.

[0060] Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir. Add 30% sodium hydroxide solution to adjust the pH to 8.0. Heat to 40℃ and add 35% of the total amount of urea. Slowly heat to 90℃ within 30℃ and maintain this temperature for 1 hour. Add hydroxymethylated sodium lignin sulfonate and stir evenly. Add 30% formic acid solution dropwise to adjust the pH to 5. Maintain this temperature for 90 minutes. Immediately add 30% sodium hydroxide solution dropwise to adjust the pH to 7.5. Add 33% of the total amount of urea. React at 85℃ for 30 minutes. Add 32% of the total amount of urea, melamine, and glutaraldehyde. React at 80℃ for 30 minutes. Adjust the pH to 7.5, cool to 40℃, and discharge. The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine is 1:1.00:0.05:0.05. The amount of hydroxymethylated sodium lignin sulfonate added is 4 wt% of the modified urea-formaldehyde resin adhesive.

[0061] Step 3, Particleboard Preparation: Take the core and surface particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 10 minutes to obtain the core and surface layers. The core particleboard is laid horizontally by the directional laying head, and the surface particleboard is laid vertically by the directional laying head. Lay the particleboard in the order of "surface layer-core layer-surface layer", pre-press at 0.8MPa for 2 minutes, and then hot-press at 1.5MPa and 200℃ for 2 minutes. Cooling will produce the particleboard, which is the high-strength flame-retardant and moisture-proof furniture board.

[0062] The particleboard has a particleboard layer-core-core layer particleboard mass ratio of 1:1:1; core layer adhesive application is 4% and surface layer adhesive application is 10%; flame retardant application is 10 wt% of particleboard; waterproofing agent application is 3 wt% of particleboard; and modified nanocellulose application is 2 wt% of particleboard.

[0063] The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: Sodium lignin sulfonate is dissolved in water, the pH is adjusted to 11 with 30% sodium hydroxide, formaldehyde solution is slowly added dropwise, and the reaction is carried out at 90℃ for 2 hours. Then, 30% formic acid is added dropwise to adjust the pH to 2. After centrifugation and washing, the solution is dried at 60℃ for 12 hours to obtain hydroxymethylated sodium lignin sulfonate. The material ratio of sodium lignin sulfonate to formaldehyde solution is 3:1.

[0064] The preparation steps of modified nanocellulose are as follows: the excess waste material in step 1 is crushed and sieved through a 100-mesh bamboo powder. 1g of sieved bamboo powder is placed in 100ml of deionized water, 0.02g of 2,2,6,6-tetramethylpiperidine oxide and 0.1g of sodium bromide are added, and 60ml of 5% sodium hypochlorite solution is added. The mixture is stirred for 3h, during which hydrochloric acid or alkali solution is added dropwise to control the pH at 10. After the reaction is completed, 10ml of anhydrous ethanol is added sequentially, filtered and washed, and dispersed in deionized water to 1.5wt%. It is then mixed evenly with 100ml of polyethyleneimine, heated to 100℃, and stirred for 10h. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, and the process is repeated 3 times. The mixture is then freeze-dried to obtain modified nanocellulose.

[0065] Testing and Experiment

[0066] The physical and mechanical properties of the boards prepared in Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T 41715.

[0067] Flame retardant performance: Limiting oxygen index (LOI) was tested using an oxygen index meter.

[0068]

[0069] Based on the above experimental data, the board prepared in Example 3 has good physical and mechanical properties and flame retardant properties; Comparative Example 1 without the addition of sodium hydroxymethyl lignin sulfonate and Comparative Example 2 without modification of nanocellulose both have an impact on the bonding performance and mechanical properties of the board, and the formaldehyde release increases; Comparative Example 3 replaced the waterproofing agent with a single molten paraffin, which reduced the moisture resistance of the board.

[0070] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, flame-retardant, moisture-resistant furniture board, characterized by, Includes the following steps: Step 1: Processing bamboo shavings: After shaving the bamboo into pieces, steam and soften it for 24 hours. Control the moisture content to 65-70% before shaving it. Then dry it to control the moisture content to 2-5%. Select the core layer shavings (50-120mm long, 20-50mm wide, and 0.3-0.8mm thick), the surface layer shavings (20-50mm long, 20-50mm wide, and 0.3-0.8mm thick), and any excess waste materials for later use. Step 2: Preparation of modified urea-formaldehyde resin adhesive: Take formaldehyde solution and stir, add sodium hydroxide solution to adjust pH to 7.5-8.0, heat to 40℃ and add the first batch of urea, slowly heat to 90℃ within 30-40 minutes, keep warm for 1 hour, add hydroxymethylated sodium lignin sulfonate, stir evenly, add formic acid solution dropwise to adjust pH to 4.8-5.1, keep warm for 1-2 hours and immediately add sodium hydroxide solution dropwise to adjust pH to 7.5-8.0, add the second batch of urea, react at 80-85℃ for 30 minutes, then add the third batch of urea, melamine, and glutaraldehyde, react at 70-80℃ for 30 minutes, adjust pH to 7.5-8.0, cool to 40-50℃, and discharge the material; Step 3, Particleboard Preparation: Take the core layer and surface layer particleboard prepared in Step 1, mix them separately with modified nanocellulose and flame retardant, and stir evenly. Then add the modified urea-formaldehyde resin and waterproofing agent prepared in Step 2, and continue stirring for 5-10 minutes to obtain the core layer and surface layer in sequence. The core layer particleboard is laid horizontally by the directional laying head, and the surface layer particleboard is laid vertically by the directional laying head. Lay it according to the order of "surface layer-core layer-surface layer". After pre-pressing, hot press it to obtain particleboard, which is the high-strength flame-retardant and moisture-proof furniture board. The preparation steps of hydroxymethylated sodium lignin sulfonate are as follows: dissolve sodium lignin sulfonate in water, adjust the pH to 11 with sodium hydroxide, slowly add formaldehyde solution, react at 90℃ for 2 hours, adjust the pH to 2 with formic acid, centrifuge and wash, and dry at 60℃ for 12 hours to obtain hydroxymethylated sodium lignin sulfonate; the amount of hydroxymethylated sodium lignin sulfonate added is 2-4 wt% of the modified urea-formaldehyde resin adhesive. The preparation steps of modified nanocellulose in step 3 are as follows: the excess waste material in step 1 is crushed, sieved through a 100-mesh bamboo powder, placed in deionized water, 2,2,6,6-tetramethylpiperidine oxide and sodium bromide are added, and a 3-5% sodium hypochlorite solution is added. The mixture is stirred for 3 hours, during which hydrochloric acid or alkaline solution is added dropwise to control the pH to 10-10.

5. After the reaction is completed, anhydrous ethanol is added, the mixture is filtered and washed, dispersed in deionized water, mixed evenly with polyethyleneimine, heated to 100℃, stirred and reacted for 10 hours. After the reaction is completed, the mixture is centrifuged, the supernatant is discarded, the process is repeated 2-3 times, and the mixture is freeze-dried to obtain modified nanocellulose. The amount of flame retardant used is 5-10 wt% of particleboard; the amount of waterproofing agent used is 1-3 wt% of particleboard; and the amount of modified nanocellulose used is 1-2 wt%.

2. The method for preparing high-strength, flame-retardant, moisture-resistant furniture plate according to claim 1, characterized in that, The molar ratio of urea, formaldehyde, glutaraldehyde, and melamine in the modified urea-formaldehyde resin adhesive prepared in step 2 is 1:(1.00-1.05):(0.02-0.05):(0.03-0.05).

3. The method for preparing high-strength, flame-retardant, moisture-resistant furniture plate according to claim 1, characterized in that, The preparation steps of the flame retardant in step 3 are as follows: place polyethyleneimine in anhydrous ethanol and stir to mix, add ammonium polyphosphate and stir for 2-3 hours, then heat to 60-70℃, filter and wash, and dry at 60℃ to obtain the flame retardant.

4. The method for preparing high-strength, flame-retardant, moisture-resistant furniture plate according to claim 1, characterized in that, The preparation steps of the waterproofing agent are as follows: weigh paraffin wax, stearic acid and microcrystalline wax in a mass ratio of 1:1:1 and mix them, then melt them at 100℃.

5. The method for preparing high-strength, flame-retardant, moisture-resistant furniture plate according to claim 1, characterized in that, The particle size ratio of each layer in the surface layer-core layer-surface layer is 1:1:1; the adhesive application rate of the core layer is 2-5%, and the adhesive application rate of the surface layer is 5-10%.

6. The method for preparing a high-strength flame-retardant and moisture-proof furniture board according to claim 1, characterized in that, In step 3, the pre-compression pressure is 0.5-0.8 MPa, and the pre-compression time is 2-3 min; after pre-compression, the hot-compression pressure is 1.5-1.8 MPa, the hot-compression temperature is 190-200℃, and the hot-compression time is 1-2 min.

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