Environment-friendly moisture-proof density board and preparation method thereof

Abstract

The present application relates to the field of sealing plate, and specifically relates to an environment-friendly moisture-proof density board and a preparation method thereof, which comprises the following components in parts by mass: modified wood fiber 50-70 parts, bamboo fiber 30-50 parts, modified isocyanate adhesive 8-15 parts, nano silicon dioxide 0.5-3 parts, vegetable oil release agent 0.3-1 part, and curing agent 0.08-0.15 part. The present application combines natural renewable raw materials with innovative materials, combines fine chemical process regulation and multifunctional integrated design, significantly reduces environmental load compared with the prior art, improves moisture resistance, and simultaneously considers flame retardation and antibacterial performance, and optimizes structural stability, and can be widely applied to furniture manufacturing, building decoration and high-humidity environment scenes, and has green and sustainable and high-adaptability application prospect.

Description

Technical Field

[0001] This invention relates to the field of sealing boards, and more particularly to an environmentally friendly moisture-proof density board and its preparation method. Background Technology

[0002] Medium-density fiberboard (MDF) is a type of engineered wood product made from wood fibers or other plant fibers through processes such as crushing, gluing, and hot pressing. It features uniform structure, smooth surface, and excellent processing performance, and is widely used in furniture manufacturing, interior decoration, and packaging materials.

[0003] In existing technologies, MDF (medium-density fiberboard) mostly uses urea-formaldehyde resin or phenolic resin as adhesives. During its preparation and subsequent use, it easily releases volatile harmful substances such as formaldehyde, resulting in poor environmental performance and long-term health hazards. In addition, ordinary MDF is highly hygroscopic, easily absorbing water and swelling in humid environments, which reduces its strength and may even breed mold, limiting its application in kitchens, bathrooms and other scenarios. Furthermore, existing MDF has limited functionality and requires post-processing to achieve functions such as flame retardancy, which not only increases costs but may also introduce harmful chemicals.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop an environmentally friendly and moisture-proof MDF and its preparation method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose an environmentally friendly moisture-proof MDF and its preparation method, so as to solve the problems of insufficient environmental protection, poor moisture-proof performance and single function in the prior art.

[0006] To achieve the above objectives, the present invention provides an environmentally friendly moisture-proof MDF and its preparation method.

[0007] An environmentally friendly and moisture-proof MDF board comprises the following components in parts by weight: 50-70 parts modified wood fiber, 30-50 parts bamboo fiber, 8-15 parts modified isocyanate adhesive, 0.5-3 parts nano silica, 0.3-1 parts vegetable oil release agent, and 0.08-0.15 parts curing agent.

[0008] A method for preparing an environmentally friendly, moisture-proof MDF board, characterized by the following preparation method:

[0009] Step S1: Add the modified wood fiber and bamboo fiber to the mixer, then add the modified isocyanate adhesive, nano silica, vegetable oil release agent and ammonium chloride curing agent. Stir at 800-1200 rpm for 3-5 minutes. After stirring, dry to obtain mixed fibers.

[0010] Step S2: Place the mixed fibers into a multi-roller pre-press, heat to 20-30℃, pressure 1-2MPa, pre-press for 10-15min, remove and place into a multi-layer hot press, heat to 180-200℃, pressure 3-5MPa, extrude for 12-18min, then reduce pressure to 0.5-1MPa, cool to 160-170℃, continue for 1-2min, hot pressing ends, cool to 30-50℃, cool for 20-30min, to obtain environmentally friendly moisture-proof MDF;

[0011] The modified wood fiber is grafted wood fiber;

[0012] The modified isocyanate adhesive is a triazine-modified isocyanate adhesive;

[0013] The silane long chains grafted onto the fiber surface form a hydrophobic barrier, while nano-silica is uniformly dispersed between the fibers, filling microscopic pores and inhibiting moisture penetration. The two work synergistically to enhance the moisture resistance of the MDF and reduce the fiber's moisture absorption and expansion rate. Flame-retardant and antibacterial groups are also introduced. At the same time, a triazine ring structure is introduced into the adhesive, providing a high cross-linking density, enhancing moisture resistance and mechanical strength, and it does not contain formaldehyde volatilization. This significantly improves the interfacial bonding force between the fiber and the adhesive, and enhances the internal density of the board. In addition, the vegetable oil release agent is environmentally friendly and non-toxic, avoiding the residual pollution of traditional release agents and reducing the adhesion loss between the fiber and the mold during hot pressing.

[0014] Preferably, the grafted wood fiber is prepared by the following method:

[0015] Step A1: Add the lignocellulose to a mixed solution of toluene, acetone and methanol, extract for 5-7 hours, heat to 90-110℃, and dry for 22-26 hours to obtain purified lignocellulose;

[0016] Step A2: Add the purified lignocellulose to the pyridine solution, then add undecyneic acid, stir evenly, heat to 110-120℃, react for 2-4 hours, and the reaction is complete to obtain esterified lignocellulose;

[0017] Step A3: Add esterified wood fibers to toluene solvent, add initiator benzoyl peroxide, silane-containing long-chain flame retardant styrene propylene and silane-containing antibacterial styrene propylene, stir and mix, heat to 90-110℃, react for 2-4 hours, filter to obtain grafted wood fibers.

[0018] Preferably, the volume ratio of toluene, acetone and methanol in step A1 is 3.8-4.2:0.8-1.2:1;

[0019] The mass ratio of purified lignocellulose to undecyneic acid in step A2 is 1:2.5-3;

[0020] The mass ratio of esterified wood fiber, initiator, silane-containing long-chain flame retardant styrene propylene and silane-containing antibacterial styrene propylene in step A3 is 1:0.06-0.12:8.5-17.2:4.75-9.55.

[0021] Preferably, the silane-containing long-chain flame-retardant styrene is prepared by the following method:

[0022] Step B1: Add paraformaldehyde to chloroform solvent, then add CaH2, heat to 20-30℃, react for 20-40 min, heat to 50-70℃, add 11-aminoundecyltrimethoxysilane, heat to 75-95℃, add 5-(2-propenyl)1,3-benzenediol, react for 50-70 min, to obtain intermediate 1;

[0023] Step B2: Under nitrogen atmosphere, add intermediate 1 to 1-thiophospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane, heat to 90-110℃, fractionate the reaction for 1-3 hours, then heat to 130-150℃, fractionate the reaction for 4-6 hours, and the reaction is completed to obtain silane-containing long-chain flame-retardant styrene.

[0024] Preferably, the mass ratio of paraformaldehyde, CaH2, 11-aminoundecyltrimethoxysilane and 5-(2-propenyl)1,3-benzenediol in step B1 is 1:1.0-1.1:4.7-4.9:1.1-1.3;

[0025] The mass ratio of intermediate 1 to 1-thiophospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane in step B2 is 1.4-1.5:1.

[0026] Preferably, the silane-containing antibacterial styrene is prepared by the following method:

[0027] Step C1: Add tetrahydroxymethyl phosphate to diethylene glycol dimethyl ether solvent, heat to 20-25℃, add 3-(trichlorosilyl)1-propylamine, heat to 50-60℃, react for 50-70 min, heat to 120-140℃, react for 8-10 h, cool, crystallize, filter, and obtain cage-like quaternary phosphate organosilicon ester;

[0028] Step C2: Add paraformaldehyde to chloroform solvent, then add CaH2, heat to 20-30℃, react for 20-40 min, heat to 50-70℃, add cage-like quaternary phosphate organosilicon ester, heat to 75-95℃, add 5-(2-propenyl)1,3-benzenediol, react for 50-70 min, to obtain styrene propene containing silane antibacterial properties.

[0029] Preferably, the mass ratio of tetrahydroxymethylphosphonic acid sulfate to 3-(trichlorosilyl)-1-propylamine in step C1 is 1:0.85-0.95;

[0030] The mass ratio of paraformaldehyde, CaH2, cage-like quaternary phosphate organosilicon ester and 5-(2-propenyl)1,3-benzenediol in step C2 is 1:1.0-1.1:4.2-4.3:1.1-1.3.

[0031] Preferably, the triazine-modified isocyanate adhesive is prepared by the following method:

[0032] Step D1: Add cyanuric chloride to acetone solvent, add 5-amino-1,3-dihydroxytoluene, heat to 10-20℃, react for 20-40 min, then heat to 50-70℃, reflux for 2-3 h, the reaction is complete, and a triazine-containing polyol is obtained.

[0033] Step D2: Under nitrogen atmosphere, toluene-2,4-diisocyanate, polyethylene glycol 400, and triazine-containing polyol are added to a three-necked flask, stirred and mixed evenly, heated to 80-90℃, reacted for 2-4 hours, cooled to 35-55℃, dimethylolpropionic acid and 1,4-butanediol are added, heated to 70-90℃, reacted for 30-90 minutes, cooled to 35-50℃, dibutyltin dilaurate and stannous octoate catalysts are added, heated to 60-80℃, reacted for 3-5 hours, the reaction is complete, cooled to 30-50℃, triphenyl phosphate stabilizer is added, and diluted with ethyl acetate to obtain triazine-modified isocyanate adhesive.

[0034] Preferably, the mass ratio of cyanuric chloride to 5-amino-1,3-dihydroxytoluene in step D1 is 1:2.4-2.5;

[0035] The mass ratio of toluene-2,4-diisocyanate, polyethylene glycol 400, triazine-containing polyol, dimethylolpropionic acid, 1,4-butanediol, dibutyltin dilaurate, stannous octoate, and triphenyl phosphate in step D2 is 2.8-3.2:1.5-1.7:1:0.26-0.29:0.28-0.32:0.10-0.12:0.11-0.13:0.002-0.01.

[0036] The beneficial effects of this invention are:

[0037] This invention provides an environmentally friendly moisture-proof MDF and its preparation method. By combining natural renewable raw materials with innovative materials, combined with refined process control and multi-functional integrated design, this invention significantly reduces environmental impact and improves moisture resistance compared with existing technologies. It also takes into account flame retardant and antibacterial properties and optimizes structural stability. It can be widely used in furniture manufacturing, building decoration and high humidity environments, and has a promising future of green sustainability and high adaptability. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0039] Example 1: The preparation method of silane-containing long-chain flame-retardant styrene propylene is as follows:

[0040] S1: Add 100g of paraformaldehyde to 200mL of chloroform solvent, then add 100g of CaH2, heat to 20℃, react for 40min, heat to 50℃, add 470g of 11-aminoundecyltrimethoxysilane, heat to 75℃, add 110g of 5-(2-propenyl)1,3-benzenediol, react for 50min to obtain intermediate 1;

[0041] S2: Under nitrogen atmosphere, 140g of intermediate 1 was added to 100g of 1-thiophospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane, heated to 90℃, and fractionated for 3h. Then the temperature was raised to 130℃ and fractionated for 6h. The reaction was completed to obtain silane-containing long-chain flame-retardant styrene.

[0042] Example 2: The preparation method of silane-containing long-chain flame-retardant styrene propylene is as follows:

[0043] S1: Add 100g of paraformaldehyde to 200mL of chloroform solvent, then add 105g of CaH2, heat to 25℃, react for 30min, heat to 60℃, add 480g of 11-aminoundecyltrimethoxysilane, heat to 80℃, add 120g of 5-(2-propenyl)1,3-benzenediol, react for 60min to obtain intermediate 1;

[0044] S2: Under nitrogen atmosphere, 145g of intermediate 1 was added to 100g of 1-thiophospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane, heated to 100℃, and fractionated for 2h. Then the temperature was raised to 140℃ and fractionated for 5h. The reaction was completed to obtain silane-containing long-chain flame-retardant styrene.

[0045] Example 3: The preparation method of silane-containing long-chain flame-retardant styrene propylene is as follows:

[0046] S1: Add 100g of paraformaldehyde to 200mL of chloroform solvent, then add 110g of CaH2, heat to 30℃, react for 20min, heat to 70℃, add 490g of 11-aminoundecyltrimethoxysilane, heat to 75℃, add 130g of 5-(2-propenyl)1,3-benzenediol, react for 50min to obtain intermediate 1;

[0047] S2: Under nitrogen atmosphere, 150g of intermediate 1 was added to 100g of 1-thiophospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane, heated to 110℃, and fractionated for 1h. Then the temperature was raised to 150℃ and fractionated for 4h. The reaction was completed to obtain silane-containing long-chain flame-retardant styrene.

[0048] Example 4: The preparation method of styrene propene containing silane antibacterial agent is as follows:

[0049] S1: Add 100g of tetrahydroxymethyl phosphate sulfate to 200mL of diethylene glycol dimethyl ether solvent, heat to 20℃, add 85g of 3-(trichlorosilyl)1-propylamine, heat to 50℃, react for 70min, heat to 120℃, react for 10h, cool, crystallize, filter, and obtain cage-like quaternary phosphate organosilicon ester.

[0050] S2: Add 100g of paraformaldehyde to 200mL of chloroform solvent, then add 100g of CaH2, heat to 20℃, react for 40min, heat to 50℃, add 420g of cage-like quaternary phosphate organosilicon ester, heat to 75℃, add 110g of 5-(2-propenyl)1,3-benzenediol, react for 70min to obtain styrene propene containing silane antibacterial properties.

[0051] Example 5: The preparation method of styrene propene containing silane antibacterial agent is as follows:

[0052] S1: Add 100g of tetrahydroxymethyl phosphate to 200mL of diethylene glycol dimethyl ether solvent, heat to 22℃, add 90g of 3-(trichlorosilyl)1-propylamine, heat to 55℃, react for 60min, heat to 130℃, react for 9h, cool, crystallize, filter, and obtain cage-like quaternary phosphate organosilicon ester.

[0053] S2: Add 100g of paraformaldehyde to 200mL of chloroform solvent, then add CaH2, heat to 25℃, react for 30min, heat to 60℃, add 420g of cage-like quaternary phosphate organosilicon ester, heat to 80℃, add 120g of 5-(2-propenyl)1,3-benzenediol, react for 60min to obtain styrene propene containing silane antibacterial properties.

[0054] Example 6: The preparation method of styrene propene containing silane antibacterial agent is as follows:

[0055] S1: Add 100g of tetrahydroxymethyl phosphate to 200mL of diethylene glycol dimethyl ether solvent, heat to 25℃, add 95g of 3-(trichlorosilyl)1-propylamine, heat to 50℃, react for 70min, heat to 120℃, react for 10h, cool, crystallize, filter, and obtain cage-like quaternary phosphate organosilicon ester.

[0056] S2: Add 100g of paraformaldehyde to 200mL of chloroform solvent, then add 110g of CaH2, heat to 30℃, react for 20min, heat to 70℃, add 430g of cage-like quaternary phosphate organosilicon ester, heat to 95℃, add 130g of 5-(2-propenyl)1,3-benzenediol, react for 50min to obtain styrene propene containing silane antibacterial properties.

[0057] Example 7: The method for preparing grafted wood fiber is as follows:

[0058] S1: Add 100g of lignocellulose to a mixed solution of 38mL toluene, 8mL acetone and 10mL methanol, extract for 5h, heat to 110℃ and dry for 22h to obtain purified lignocellulose.

[0059] S2: Add 100g of purified lignocellulose to 100mL of pyridine solution, then add 250g of undecyneic acid, stir evenly, heat to 110℃, react for 4h, and the reaction is complete to obtain esterified lignocellulose.

[0060] S3: Add 100g of esterified wood fiber to 1000mL of toluene solvent, add 6g of initiator benzoyl peroxide, 850g of silane-containing long-chain flame retardant styrene and 475g of silane-containing antibacterial styrene, stir and mix, heat to 90℃, react for 4h, filter, and obtain grafted wood fiber.

[0061] Example 8: The method for preparing grafted wood fiber is as follows:

[0062] S1: Add 100g of lignocellulose to a mixed solution of 40mL toluene, 10mL acetone and 10mL methanol, extract for 6h, heat to 100℃ and dry for 24h to obtain purified lignocellulose.

[0063] S2: Add 100g of purified lignocellulose to 100mL of pyridine solution, then add 280g of undecyneic acid, stir evenly, heat to 115℃, react for 3h, and the reaction is complete to obtain esterified lignocellulose.

[0064] S3: Add 100g of esterified wood fiber to 1000mL of toluene solvent, add 10g of initiator benzoyl peroxide, 1000g of silane-containing long-chain flame retardant styrene and 500g of silane-containing antibacterial styrene, stir and mix, heat to 90-110℃, react for 2-4h, filter, and obtain grafted wood fiber.

[0065] Example 9: The method for preparing grafted wood fiber is as follows:

[0066] S1: Add 100g of lignocellulose to a mixed solution of 42mL toluene, 12mL acetone and 10mL methanol, extract for 7h, heat to 90℃ and dry for 26h to obtain purified lignocellulose.

[0067] S2: Add 100g of purified lignocellulose to 100mL of pyridine solution, then add 300g of undecyneic acid, stir evenly, heat to 120℃, react for 2h, and the reaction is complete to obtain esterified lignocellulose.

[0068] S3: Add 100g of esterified wood fiber to toluene solvent, add 12g of initiator benzoyl peroxide, 1720g of silane-containing long-chain flame retardant styrene and 955g of silane-containing antibacterial styrene, stir and mix, heat to 110℃, react for 2h, filter, and obtain grafted wood fiber.

[0069] Example 10: The preparation method of triazine-modified isocyanate adhesive is as follows:

[0070] S1: Add 100g of cyanuric chloride to 100mL of acetone solvent, add 240g of 5-amino-1,3-dihydroxytoluene, heat to 10℃, react for 40min, then heat to 70℃, reflux for 2h, and the reaction is complete to obtain a triazine-containing polyol.

[0071] S2: Under nitrogen atmosphere, 280g of toluene-2,4-diisocyanate, 150g of polyethylene glycol 400, and 100g of triazine-containing polyol were added to a three-necked flask, stirred and mixed evenly, heated to 80℃, reacted for 4h, cooled to 35℃, added 26g of dimethylolpropionic acid and 28g of 1,4-butanediol, heated to 70℃, reacted for 90min, cooled to 35℃, added 10g of catalyst dibutyltin dilaurate and 11g of stannous octoate, heated to 60℃, reacted for 5h, and the reaction was completed. The temperature was then lowered to 30℃, and 0.2g of stabilizer triphenyl phosphate was added and diluted with ethyl acetate to obtain triazine-modified isocyanate adhesive.

[0072] Example 11: The preparation method of triazine-modified isocyanate adhesive is as follows:

[0073] S1: Add 100g of cyanuric chloride to 100mL of acetone solvent, add 245g of 5-amino-1,3-dihydroxytoluene, heat to 15℃, react for 30min, then heat to 60℃ and reflux for 2.5h. The reaction is complete, and a triazine-containing polyol is obtained.

[0074] S2: Under nitrogen atmosphere, 300g of toluene-2,4-diisocyanate, 160g of polyethylene glycol 400, and 100g of triazine-containing polyol were added to a three-necked flask, stirred and mixed evenly, heated to 85℃, reacted for 3h, cooled to 40℃, added 28g of dimethylolpropionic acid and 30g of 1,4-butanediol, heated to 80℃, reacted for 60min, cooled to 40℃, added 11g of catalyst dibutyltin dilaurate and 12g of stannous octoate, heated to 70℃, reacted for 4h, and the reaction was completed. The temperature was then lowered to 40℃, and 0.5g of stabilizer triphenyl phosphate was added and diluted with ethyl acetate to obtain triazine-modified isocyanate adhesive.

[0075] Example 12: The preparation method of triazine-modified isocyanate adhesive is as follows:

[0076] S1: Add 100g of cyanuric chloride to 100mL of acetone solvent, add 250g of 5-amino-1,3-dihydroxytoluene, heat to 20℃, react for 20min, then heat to 70℃, reflux for 2h, and the reaction is complete to obtain a triazine-containing polyol.

[0077] S2: Under nitrogen atmosphere, 320g of toluene-2,4-diisocyanate, 170g of polyethylene glycol 400, and 100g of triazine-containing polyol were added to a three-necked flask, stirred and mixed evenly, heated to 90℃, reacted for 2h, cooled to 55℃, added 29g of dimethylolpropionic acid and 32g of 1,4-butanediol, heated to 90℃, reacted for 30min, cooled to 50℃, added 12g of catalyst dibutyltin dilaurate and 13g of stannous octoate, heated to 80℃, reacted for 3h, and the reaction was completed. The temperature was then lowered to 50℃, added 1g of stabilizer triphenyl phosphate, and diluted with ethyl acetate to obtain triazine-modified isocyanate adhesive.

[0078] Example 13: A method for preparing an environmentally friendly moisture-proof MDF board, the method of which is as follows:

[0079] S1: Add 500g of modified wood fiber and 300g of bamboo fiber to a mixer, then add 80g of modified isocyanate adhesive, 5g of nano silica, 3g of vegetable oil release agent and 0.8g of curing agent ammonium chloride. Stir at 800rpm for 5min. After stirring, dry to obtain mixed fiber.

[0080] S2: Place the mixed fibers into a multi-roller pre-press, heat to 20℃, pressure 2MPa, pre-press for 10min, remove and place into a multi-layer hot press, heat to 200℃, pressure 3MPa, extrude for 18min, then reduce pressure to 0.5MPa, reduce temperature to 170℃, continue for 1min, hot pressing ends, reduce temperature to 50℃, cool for 20min to obtain environmentally friendly moisture-proof MDF.

[0081] Example 14: A method for preparing an environmentally friendly moisture-proof MDF board, the method of which is as follows:

[0082] S1: Add 600g of modified wood fiber and 400g of bamboo fiber to a mixer, then add 100g of modified isocyanate adhesive, 20g of nano silica, 5g of vegetable oil release agent and 1g of curing agent ammonium chloride. Stir at 1000rpm for 4min. After stirring, dry to obtain mixed fiber.

[0083] S2: Place the mixed fibers into a multi-roller pre-press, heat to 25℃, pressure 1.5MPa, pre-press for 13min, remove and place into a multi-layer hot press, heat to 190℃, pressure 4MPa, extrude for 16min, then reduce pressure to 0.75MPa, reduce temperature to 165℃, continue for 1.6min, hot pressing ends, reduce temperature to 40℃, cool for 25min to obtain environmentally friendly moisture-proof MDF.

[0084] Example 15: A method for preparing an environmentally friendly moisture-proof MDF board, the method of which is as follows:

[0085] S1: Add 700g of modified wood fiber and 500g of bamboo fiber to a mixer, then add 150g of modified isocyanate adhesive, 30g of nano silica, 10g of vegetable oil release agent and 1.5g of curing agent ammonium chloride. Stir at 1200rpm for 3 minutes. After stirring, dry to obtain mixed fiber.

[0086] S2: Place the mixed fibers into a multi-roller pre-press, heat to 30℃, pressure 1MPa, pre-press for 15min, remove and place into a multi-layer hot press, heat to 180℃, pressure 5MPa, press for 12min, then reduce pressure to 1MPa, reduce temperature to 160℃, continue for 2min, hot pressing ends, reduce temperature to 30℃, cool for 30min to obtain environmentally friendly moisture-proof MDF.

[0087] Comparative Example 1:

[0088] Compared with Example 13, this comparative example did not add nano-silica in the preparation process of the environmentally friendly moisture-proof MDF. All other steps and parameters were the same, and will not be repeated here. The final result was an environmentally friendly moisture-proof MDF.

[0089] Comparative Example 2:

[0090] Compared with Example 13, this comparative example only replaces "triazine modified isocyanate adhesive" with "isocyanate adhesive". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, an environmentally friendly moisture-proof MDF is obtained.

[0091] Comparative Example 3:

[0092] Compared with Example 13, this comparative example only replaces "silane-containing long-chain flame-retardant styrene propylene" with "styrene propylene". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, an environmentally friendly moisture-proof MDF is obtained.

[0093] Comparative Example 4:

[0094] This comparative example differs from Example 13 only in that "bamboo fiber" is replaced with "wood fiber". All other steps and parameters are the same, and will not be repeated here. The final result is an environmentally friendly and moisture-proof MDF.

[0095] Comparative Example 5:

[0096] Compared with Example 13, this comparative example only replaces "silane-containing antibacterial styrene" with "styrene". All other steps and parameters are the same, and will not be repeated here. The final result is an environmentally friendly moisture-proof MDF.

[0097] Performance testing:

[0098] Formaldehyde emission testing:

[0099] 1. Referring to the GB / T 17657-2013 testing standard, a 0.225m depth was used. 2 Climate chamber, equipped with air purification system, temperature and humidity control system, ventilation control system, etc.; dual-channel atmospheric sampler QC-2 type; high performance liquid chromatograph, Shanghai Tianmei TechcompLC-2130 type; chromatographic column: SUPELCOSILC™ LC-18 column, 250mm×4.6mm, 5μm;

[0100] 2. Small climate chamber testing conditions: Temperature: 23℃±0.5℃; Relative humidity: 50%±3‰; Air exchange rate: 0.65 times / h; Loading rate: 1:1m 2 / m 3 Two MDF boards from Examples 13-15 and Comparative Examples 1-5 were taken respectively, with dimensions of 300mm×300mm×18mm and 1300mm×75mm×18mm respectively;

[0101] 3. Method: First, clean the inside of the climate chamber, then introduce purified air and place the board material inside. After the conditions inside the climate chamber stabilize, collect samples using a dual-channel sampler at a sampling rate of 0.5-1.0 L / min for 60 min, continuously sampling for 28 days. Determine the formaldehyde release concentration by high-performance liquid chromatography (HPLC).

[0102] 4. Evaluation criteria: Formaldehyde emission must be ≤0.03 mg / m³ 3 It is superior to the E0 standard (≤0.05mg / m³). 3 );

[0103] VOC emission testing

[0104] 1. In accordance with the ISO16000-6 testing standard, a CC-FID gas chromatograph (Shanghai Tianmei GC-7900) was used; the chromatographic column was an SE-30 quartz capillary column, 50m x 0.25min x 0.1μm.

[0105] 2. Analyze the total volatile organic compounds (TVOC) of the boards. Take the MDF boards of Examples 13-15 and Comparative Examples 1-5 respectively, and collect the gas after equilibration in a sealed chamber for 72 hours.

[0106] Table 1. Detection data of Examples 13-15 and Comparative Examples 1-5

[0107] project <![CDATA[Formaldehyde emission (mg / m 3 )]]> <![CDATA[TVOC emission (μg / m 3 )]]> Example 13 0.025 95 Example 14 0.028 92 Example 15 0.023 78 Comparative Example 1 0.038 120 Comparative Example 2 0.045 150 Comparative Example 3 0.032 105 Comparative Example 4 0.035 130 Comparative Example 5 0.030 95

[0108] Moisture resistance test

[0109] Referring to the GB / T 17657-2013 testing standard, the density boards of Examples 13-15 and Comparative Examples 1-5 were placed at a temperature of (20±2)℃ and a relative humidity of (65±5)% until their mass became constant. The thickness h1 at the center point of the specimen was measured to an accuracy of 0.01 mm, with the measurement point at the intersection of the diagonals of the specimen. Then, the specimens were placed in a constant temperature water bath at (20±2)℃ and soaked for 24 hours. After soaking, the specimens were removed, the surface water was wiped off, and the thickness h2 was measured at the original measurement point to an accuracy of 0.01 mm. The TS of the specimen was calculated according to the following formula:

[0110] Long-term moisture resistance test

[0111] 1. In accordance with the ASTM D1037 test standard, a constant temperature and humidity chamber was used with a temperature of 38±1℃ and a humidity of 90±2%. The MDF boards of Examples 13-15 and Comparative Examples 1-5 were cut into standard sizes of 300mm×300mm×18mm, and three samples were taken.

[0112] 2. Place the sample horizontally on a non-hygroscopic support with a spacing of ≥50mm, avoiding contact with the chamber walls or other samples, and maintain 38℃ and 90% humidity for 7 consecutive days to simulate a long-term high-humidity environment;

[0113] 3. Formula for calculating the thickness change rate:

[0114] In the formula: T1-----the thickness measured at the measurement point before the test, in mm;

[0115] T2-----After the test, the thickness is measured at the measuring point, in mm;

[0116] ΔT-----Thickness change rate, %.

[0117] Table 2. Moisture-proof performance test data of Examples 13-15 and Comparative Examples 1-5

[0118]

[0119]

[0120] Flame retardant performance testing

[0121] According to the GB / T 2406.2 test standard, the limiting oxygen index was measured using a limiting oxygen index meter HC-2C. The combustion performance of Examples 13-15 and Comparative Examples 1-5 was determined and analyzed, and the average of five measurement results was taken.

[0122] Vertical burning test

[0123] Referring to the UL94 V-0 test standard, samples were prepared from MDF boards of Examples 13-15 and Comparative Examples 1-5 according to the standard size of 125mm×13mm×3mm. The samples were vertically suspended in the combustion chamber, and the burning time and the ignition of cotton fibers by dripping material were recorded.

[0124] Table 3 Flame retardancy test data of Examples 13-15 and Comparative Examples 1-5

[0125]

[0126]

[0127] Antimicrobial properties testing: Refer to ISO 22196 testing standard;

[0128] The experimental bacterial suspensions were directly dropped onto the density plates of Examples 13-15 and Comparative Examples 1-5, respectively, allowing the bacteria to fully contact and be exposed on the plates for a certain period of time. Then, the plates were covered with culture medium to allow the remaining bacteria to grow. The percentage decrease in bacterial count of the antibacterial samples was compared to determine their antibacterial ability.

[0129] Count colony-forming units using a magnifying glass. The steps are as follows:

[0130] 1. Preparation of bacterial culture: Take a fresh broth culture of Escherichia coli for 24 hours, shake well and let stand for 20 minutes, then dilute to a bacterial culture with a bacterial count of 105-106 CFU / mL.

[0131] 2. Inoculation: Place samples from Examples 13-15 and Comparative Examples 1-5, each measuring 5.0cm × 5.0cm, into sterile Petri dishes with a diameter of 9cm. Add 1.5mL of bacterial solution evenly, ensuring it is evenly distributed and completely absorbed on the sample. Repeat each sample 6 times and dry them in an incubator at 37℃ for 1 hour.

[0132] 3. Place the dried contaminated sample flat on the surface of a nutrient agar plate, then evenly cover the surface of the contaminated sample with semi-solid nutrient agar to a moderate thickness, and incubate in a 37% incubator for 48 hours. Set up a blank control group.

[0133] 4. Observation results: Safran staining solution was added to the semi-solid nutrient agar above and stained for 1 hour. The number of colonies on each cloth sample was counted using a magnifying glass. The average number of colonies on 6 cloth samples was calculated and recorded.

[0134] 5. Calculate the antibacterial rate: Repeat the above experiment three times, take the average value, and calculate the antibacterial rate using the following formula:

[0135]

[0136] In the formula: A is the average colony count of the control cloth sample;

[0137] B represents the average colony count of the antibacterial fabric sample.

[0138] Table 4. Antimicrobial test data of Examples 13-15 and Comparative Examples 1-5

[0139] project A(CFU / mL) B (CFU / mL) Antibacterial rate (%) Example 13 <![CDATA[1.2×10 5 ]]> <![CDATA[2.5×10 4 ]]> 79.3 Example 14 <![CDATA[1.1×10 5 ]]> <![CDATA[2.3×10 4 ]]> 79.0 Example 15 <![CDATA[1.3×10 5 ]]> <![CDATA[2.7×10 4 ]]> 79.5 Comparative Example 1 <![CDATA[1.2×10 5 ]]> <![CDATA[3.4×10 4 ]]> 71.7 Comparative Example 2 <![CDATA[1.1×10 5 ]]> <![CDATA[4.7×10 4 ]]> 57.3 Comparative Example 3 <![CDATA[1.3×10 5 ]]> <![CDATA[6.4×10 4 ]]> 50.8 Comparative Example 4 <![CDATA[1.2×10 5 ]]> <![CDATA[4.2×10 4 ]]> 65.0 Comparative Example 5 <![CDATA[1.1×10 5 ]]> <![CDATA[6.7×10 4 ]]> 39.1

[0140] compressive strength

[0141] Referring to the GB / T 17657-2013 testing standard, a universal testing machine was used to cut samples from Examples 13-15 and Comparative Examples 1-5 into 50mm×50mm×20mm pieces, apply pressure, and record the maximum load in MPa.

[0142] Internal bonding strength

[0143] Samples from Examples 13-15 and Comparative Examples 1-5 were taken respectively, cut into 50mm×50mm pieces, and their interlayer peel strength was tested by a tensile testing machine, in MPa.

[0144] Table 5 Mechanical property test data of Examples 13-15 and Comparative Examples 1-5

[0145] project Maximum load (MPa) Interlayer peel strength (MPa) Example 13 28.5 0.85 Example 14 27.8 0.82 Example 15 29.2 0.88 Comparative Example 1 21.3 0.60 Comparative Example 2 18.7 0.45 Comparative Example 3 20.5 0.55 Comparative Example 4 19.8 0.50 Comparative Example 5 22.1 0.65

[0146] Data Analysis:

[0147] As can be seen from Tables 1-5, the environmentally friendly moisture-proof MDF prepared by this invention has ultra-low formaldehyde and TVOC emissions, superior moisture-proof performance, high-efficiency flame retardancy, good antibacterial function, and excellent mechanical properties.

[0148] In contrast, Comparative Example 1, lacking the addition of nano-silica, showed a significant increase in TS and ΔT, resulting in decreased moisture resistance and increased VOC emissions. This is because nano-silica fills micropores by uniformly dispersing between fibers, reducing moisture penetration paths and enhancing the bond between the fiber and adhesive interfaces. Without it, the porosity inside the board increases, exacerbating moisture absorption and expansion, and the uneven distribution of the adhesive leads to increased release of volatile organic compounds.

[0149] Furthermore, the maximum load and interlayer peel strength of Comparative Example 1 decreased because the nano-silica not only filled the pores but also acted as a reinforcing phase dispersed in the adhesive, thereby improving the interfacial bonding between the fiber and the adhesive. The absence of nano-silica in Comparative Example 1 weakened the mechanical interlocking effect between the adhesive and the fiber, reduced stress transfer efficiency, and significantly reduced compressive strength and interlayer bonding strength. Another possible reason is that the absence of nanoparticles may affect the rheological properties of the adhesive, leading to uneven mixing and the formation of local weak areas after curing, which further weakens the overall structural density.

[0150] Comparative Example 2, by replacing the triazine-modified adhesive with a common isocyanate adhesive, resulted in excessive formaldehyde release, a decreased LOI (Lowest Opening Index), and failure to pass the vertical flammability test. Simultaneously, the compressive strength was significantly reduced. This is because the triazine-modified adhesive provides a high crosslinking density through its triazine ring structure, reducing formaldehyde release and enhancing heat resistance; the common adhesive, on the other hand, has a low degree of crosslinking, weak interfacial bonding, and lacks flame-retardant groups, leading to a comprehensive decline in environmental friendliness, flame retardancy, and mechanical properties.

[0151] Furthermore, the decrease in maximum load and interlayer peel strength in Comparative Example 2 is due to the fact that the triazine-modified adhesive forms a rigid network structure through the high crosslinking density of the triazine rings, while the ordinary adhesive has a low degree of crosslinking, higher molecular chain flexibility after curing, and poor resistance to deformation. In addition, the triazine rings may form hydrogen bonds or covalent bonds with the hydroxyl groups on the fiber surface, while the ordinary adhesive relies only on physical adsorption, resulting in weakened interfacial bonding and a significant reduction in compressive strength and interlayer strength. Another possible reason is that the ordinary adhesive has poor thermal stability and may decompose or soften during hot pressing, leading to an increase in internal defects in the adhesive layer and further affecting mechanical properties.

[0152] Comparative Example 3 had the lowest LOI and failed to meet the vertical burning standard because it did not use silane-containing long-chain flame-retardant styrene propylene. In addition, its flame retardancy was almost completely lost. This is because silane-containing long-chain flame-retardant styrene propylene forms a dense char layer during combustion through phosphorus-silicon synergy, which isolates oxygen and inhibits the spread of flame. Without this component, the MDF cannot form an effective flame-retardant barrier, resulting in an accelerated burning rate.

[0153] Furthermore, the maximum load and interlaminar peel strength of Comparative Example 3 decreased because the silane groups in the silane long-chain flame retardant styrene can form chemical bonds with the fiber surface through hydrolysis and condensation, enhancing the fiber-adhesive interface bonding. Without them, the fiber surface activity decreased, and the adhesive only physically coated the fiber, weakening the interfacial bonding force. Another possible reason is that the lack of flame retardant may cause the material to soften due to high temperature during hot pressing, reducing the contact area between the fiber and the adhesive, further weakening the structural stability.

[0154] Comparative Example 4 shows that replacing bamboo fiber with wood fiber led to an increase in TS and ΔT and a decrease in antibacterial rate. This is because bamboo fiber naturally has a hollow structure and antibacterial components such as bamboo kun, which work together with grafted wood fiber to form a hydrophobic-antibacterial network. At the same time, wood fiber has strong hygroscopicity and lacks antibacterial activity, resulting in a simultaneous deterioration of moisture-proof and antibacterial performance.

[0155] Furthermore, the maximum load and interlaminar peel strength of Comparative Example 3 decreased because bamboo fiber has a natural hollow structure and a higher aspect ratio, which can provide better mechanical support, similar to the reinforcing phase of natural composite materials. In contrast, wood fiber has a dense structure but is more brittle, resulting in decreased compressive strength and interlaminar strength. In addition, the polar groups (such as hydroxyl groups) on the surface of bamboo fiber are more likely to react with adhesives, and there may be more lignin impurities on the surface of wood fiber, reducing the interfacial bonding efficiency. Another possible reason is that the moisture absorption expansion rate of bamboo fiber is lower than that of wood fiber. After replacement, the internal stress generated by moisture absorption in the board increases, accelerating interfacial peeling.

[0156] Comparative Example 5 showed a decrease in antibacterial rate due to the replacement of silane-containing antibacterial styrene with styrene. This was because the cage-like quaternary phosphate organosilicon ester in silane-containing antibacterial styrene could release antibacterial ions and destroy the cell membrane of microorganisms. Furthermore, styrene had no antibacterial function and its insufficient hydrophobicity could lead to bacterial adhesion and growth.

[0157] Furthermore, the decrease in maximum load and interlayer peel strength in Comparative Example 3 is due to the fact that the silane groups in the silane-containing antibacterial styrene participate in the grafting reaction on the fiber surface, forming chemical bonds to enhance interfacial bonding; while styrene is only physically blended and cannot provide chemical bonding, resulting in a significant decrease in interlayer peel strength. In addition, the introduction of styrene may interfere with the adhesive curing process, forming an uneven cross-linked network and reducing compressive strength. Another possible reason is that styrene has poor hydrophobicity, which may lead to uneven distribution of adhesive on the fiber surface, with local areas of adhesive enrichment or depletion, forming stress concentration points and further weakening mechanical properties.

[0158] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0159] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing an environmentally friendly moisture-proof density board, characterized by, The preparation method is as follows: Step S1: the modified wood fiber and bamboo fiber are added into a blender, then the modified isocyanate adhesive, nano silicon dioxide, vegetable oil release agent and curing agent ammonium chloride are added, the stirring speed is 800-1200 rpm, and the stirring time is 3-5 min; after the stirring is completed, drying is performed to obtain mixed fibers; Step S2: the mixed fibers are placed into a multi-roller pre-pressing machine, the temperature is increased to 20-30 DEG C, the pressure is 1-2 MPa, and the pre-pressing time is 10-15 min; then the mixed fibers are taken out and placed into a multi-layer hot-pressing machine, the temperature is increased to 180-200 DEG C, the pressure is 3-5 MPa, and the extrusion time is 12-18 min; then the pressure is reduced to 0.5-1 MPa, the temperature is reduced to 160-170 DEG C, and the time is 1-2 min; after the hot pressing is completed, the temperature is reduced to 30-50 DEG C, and the cooling time is 20-30 min to obtain the environment-friendly moisture-proof density board; The modified wood fiber is grafted wood fiber; The modified isocyanate adhesive is triazine modified isocyanate adhesive; The preparation method of the grafted wood fiber is as follows: Step A1: the wood fiber is added into a mixed solution of toluene, acetone and methanol, and extraction is performed for 5-7 h; the temperature is increased to 90-110 DEG C, and drying is performed for 22-26 h to obtain purified wood fiber; Step A2: the purified wood fiber is added into a pyridine solution, then undecyne acid is added, and stirring is uniformly performed; the temperature is increased to 110-120 DEG C, and the reaction time is 2-4 h; after the reaction is completed, esterified wood fiber is obtained; Step A3: the esterified wood fiber is added into a toluene solvent, and initiator benzoyl peroxide, long-chain silane-containing flame-retardant styrene acrylate and silane-containing antibacterial styrene acrylate are added; stirring is performed, the temperature is increased to 90-110 DEG C, and the reaction time is 2-4 h; after filtration, grafted wood fiber is obtained.

2. The method for preparing the environmentally friendly moisture-proof MDF according to claim 1, characterized in that, In step A1, the volume ratio of toluene, acetone and methanol is 3.8-4.2:0.8-1.2:1; In step A2, the mass ratio of the purified wood fiber to undecyne acid is 1:2.5-3; In step A3, the mass ratio of the esterified wood fiber, initiator, long-chain silane-containing flame-retardant styrene acrylate and silane-containing antibacterial styrene acrylate is 1:0.06-0.12:8.5-17.2:4.75-9.

55.

3. The method of claim 2, wherein the moisture-proof environment-friendly density board is prepared by the steps of: mixing the wood powder, the binder, the water, and the wax to obtain a mixture; and drying the mixture to obtain the moisture-proof environment-friendly density board. The preparation method of the long-chain silane-containing flame-retardant styrene acrylate is as follows: Step B1: paraformaldehyde is added into a chloroform solvent, then CaH2 is added, the temperature is increased to 20-30 DEG C, and the reaction time is 20-40 min; the temperature is increased to 50-70 DEG C, 11-aminoundecyltrimethoxysilane is added, then the temperature is increased to 75-95 DEG C, and 5-(2-propenyl) 1,3-benzenediol is added; the reaction time is 50-70 min to obtain intermediate 1; Step B2: under a nitrogen environment, intermediate 1 is added into 1-sulfanylphospho-4-hydroxymethyl 2,6,7 trioxabicyclo [2,2,2] octane, the temperature is increased to 90-110 DEG C, fractional distillation is performed for 1-3 h, then the temperature is increased to 130-150 DEG C, fractional distillation is performed for 4-6 h, and after the reaction is completed, the long-chain silane-containing flame-retardant styrene acrylate is obtained.

4. The method of claim 3, wherein the moisture-proof environment-friendly density board is prepared by the steps of: mixing the wood powder, the binder, the water, and the wax to obtain a mixture; and drying the mixture to obtain the moisture-proof environment-friendly density board. The mass ratio of the paraformaldehyde, CaH2, 11-aminoundecyltrimethoxysilane and 5-(2-propenyl) 1,3-benzenediol in step B1 is 1:1.0-1.1:4.7-4.9:1.1-1.3; The mass ratio of the intermediate 1 and 1-sulfanylphospha-4-hydroxymethyl 2,6,7 trioxabicyclo[2,2,2]octane in step B2 is 1.4-1.5:

1.

5. The method of claim 1, wherein the moisture-proof environment-friendly density board is prepared by the steps of: mixing the wood powder, the binder, the water, and the wax to form a mixture; and drying the mixture to form the moisture-proof environment-friendly density board. The silane-containing antibacterial styryl compound is prepared by the following method: Step C1: tetrahydroxymethyl phosphonium sulfate is added into a diethylene glycol dimethyl ether solvent, and then 3-(trichlorosilyl) 1-propylamine is added. The temperature is raised to 50-60 DEG C, and the reaction is carried out for 50-70 min. The temperature is raised to 120-140 DEG C, and the reaction is carried out for 8-10 h. After cooling and crystallization, filtration is carried out to obtain a cage-shaped quaternary phosphonium organosilicate; Step C2: paraformaldehyde is added into a chloroform solvent, and then CaH2 is added. The temperature is raised to 20-30 DEG C, and the reaction is carried out for 20-40 min. The temperature is raised to 50-70 DEG C, and the cage-shaped quaternary phosphonium organosilicate is added. The temperature is raised to 75-95 DEG C, and 5-(2-propenyl) 1,3-benzenediol is added. The reaction is carried out for 50-70 min to obtain the silane-containing antibacterial styryl compound.

6. The method of claim 5, wherein the moisture-proof environment-friendly density board is prepared by the steps of: mixing the wood powder, the binder, the water, and the wax to obtain a mixture; and drying the mixture to obtain the moisture-proof environment-friendly density board. The mass ratio of the tetrahydroxymethyl phosphonium sulfate and 3-(trichlorosilyl) 1-propylamine in step C1 is 1:0.85-0.95; The mass ratio of the paraformaldehyde, CaH2, the cage-shaped quaternary phosphonium organosilicate and 5-(2-propenyl) 1,3-benzenediol in step C2 is 1:1.0-1.1:4.2-4.3:1.1-1.

3.

7. The method for preparing the environmentally friendly moisture-proof MDF according to claim 1, characterized in that, The triazine-modified isocyanate adhesive is prepared by the following method: Step D1: cyanuric chloride is added into an acetone solvent, and then 5-amino-1,3-dihydroxytoluene is added. The temperature is raised to 10-20 DEG C, and the reaction is carried out for 20-40 min. The temperature is raised to 50-70 DEG C, and the reaction is carried out for 2-3 h under reflux. After the reaction is completed, a triazine-containing polyol is obtained; Step D2: under a nitrogen atmosphere, toluene-2,4-diisocyanate, polyethylene glycol 400 and the triazine-containing polyol are added into a three-necked flask, and then stirring is carried out to uniformly mix them. The temperature is raised to 80-90 DEG C, and the reaction is carried out for 2-4 h. After the temperature is lowered to 35-55 DEG C, dimethylolpropionic acid and 1,4-butanediol are added. The temperature is raised to 70-90 DEG C, and the reaction is carried out for 30-90 min. After the temperature is lowered to 35-50 DEG C, a catalyst dibutyltin dilaurate and stannous octoate are added. The temperature is raised to 60-80 DEG C, and the reaction is carried out for 3-5 h. After the reaction is completed, the temperature is lowered to 30-50 DEG C, and a stabilizer triphenyl phosphate is added. Ethyl acetate is used for dilution to obtain the triazine-modified isocyanate adhesive.

8. The method of claim 7, wherein the moisture-proof environment-friendly density board is prepared by the steps of: mixing the wood powder, the binder, the water, and the wax to obtain a mixture; and drying the mixture to obtain the moisture-proof environment-friendly density board. The mass ratio of the cyanuric chloride and 5-amino-1,3-dihydroxytoluene in step D1 is 1:2.4-2.

5. The mass ratio of toluene-2, 4-diisocyanate, polyethylene glycol 400, triazine-containing polyol, dimethylol propionic acid, 1, 4-butanediol, dibutyl tin dilaurate, stannous octoate, triphenyl phosphate in step D2 is 2.8-3.2:1.5-1.7:1:0.26-0.29:0.28-0.32:0.10-0.12:0.11-0.13:0.002-0.

01.

9. The environmentally friendly moisture-proof density board prepared according to the preparation method of any one of claims 1-8, characterized in that, The components include the following components by mass: modified wood fiber 50-70 parts, bamboo fiber 30-50 parts, modified isocyanate adhesive 8-15 parts, nano silicon dioxide 0.5-3 parts, vegetable oil release agent 0.3-1 part, curing agent 0.08-0.15 part.

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