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

Abstract

The invention relates to the field of sealing plates, in particular to an environment-friendly moisture-proof density board and a preparation method thereof, and the environment-friendly moisture-proof density board comprises the following components in parts by mass: 50-70 parts of modified wood fiber, 30-50 parts of bamboo fiber, 8-15 parts of a modified isocyanate adhesive, 0.5-3 parts of nano silicon dioxide, 0.3-1 part of a vegetable oil release agent and 0.08-0.15 part of a curing agent. Through combination of natural renewable raw materials and innovative materials and combination of refined process regulation and control and multifunctional integrated design, compared with the prior art, the environment load is remarkably reduced, the moisture resistance and moisture resistance are improved, meanwhile, the flame-retardant and antibacterial properties are considered, the structural stability is optimized, and the service life is prolonged. The method can be widely applied to furniture manufacturing, building decoration and high-humidity environment scenes, and has green, sustainable and high-adaptability application prospects.

Description

Technical Field

[0001] The present invention relates to the field of sealing plates, and particularly to an environment-friendly moisture-proof density board and a preparation method thereof. Background Art

[0002] A density board is a kind of artificial board made from wood fibers or other plant fibers through processes such as crushing, sizing, and hot pressing. It has the characteristics of uniform structure, smooth surface, and excellent processing performance, and is widely used in the fields of furniture manufacturing, interior decoration, packaging materials, etc.

[0003] In the prior art, urea-formaldehyde resin or phenolic resin is mostly used as an adhesive for density boards. During its preparation process and subsequent use, it is easy to release volatile harmful substances such as formaldehyde, resulting in poor environmental protection and harm to human health during long-term use. Moreover, ordinary density boards have strong hygroscopicity, are easy to absorb water and expand, have a decrease in strength, and even breed mold in a humid environment, which limits their application in scenarios such as kitchens and bathrooms. At the same time, the existing density boards have a single function, and functions such as flame retardancy need to be achieved through post-treatment, which not only increases costs but also may introduce harmful chemical substances.

[0004] Therefore, according to the above related technologies, it is urgent to develop an environment-friendly moisture-proof density board and a preparation method thereof. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an environment-friendly moisture-proof density board and a preparation method thereof to solve the problems of insufficient environmental protection, poor moisture-proof performance, and single function in the prior art.

[0006] Based on the above purpose, the present invention provides an environment-friendly moisture-proof density board and a preparation method thereof.

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

[0008] A preparation method of an environment-friendly moisture-proof density board is characterized in that the preparation method is as follows:

[0009] Step S1: Add the modified wood fibers and bamboo fibers into a blender, then add the modified isocyanate adhesive, nano-silica, vegetable oil release agent, and curing agent ammonium chloride, with a rotation speed of 800 - 1200 rpm, stir for 3 - 5 minutes, and after stirring is completed, dry to obtain mixed fibers;

[0010] Step S2: Put the mixed fibers into a multi-roll pre-press, heat up to 20 - 30°C, apply a pressure of 1 - 2 MPa, pre-press for 10 - 15 min, take out, put into a multi-layer hot press, heat up to 180 - 200°C, apply a pressure of 3 - 5 MPa, extrude for 12 - 18 min, then reduce the pressure to 0.5 - 1 MPa, cool down to 160 - 170°C, hold for 1 - 2 min, end the hot pressing, cool down to 30 - 50°C, and cool for 20 - 30 min to obtain an environmentally friendly moisture-proof density board;

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

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

[0013] The long silicon alkane chain grafted on the fiber surface can form a hydrophobic barrier. Nano-silica is evenly dispersed among the fibers, filling the microscopic pores and inhibiting moisture penetration. The two work together synergistically to enhance the moisture-proof performance of the density board, reduce the moisture absorption and swelling rate of the fibers, and introduce flame-retardant groups and antibacterial groups. At the same time, a triazine ring structure is introduced into the adhesive to provide a high cross-linking density, enhance the moisture resistance and mechanical strength, and there is no formaldehyde volatilization, thus significantly improving the interfacial bonding force between the fiber and the adhesive, enhancing the compactness of the internal structure of the board. In addition, the vegetable oil release agent is environmentally friendly and non-toxic, avoiding the pollution caused by the residue of traditional release agents and reducing the adhesion loss between the fiber and the mold during the hot pressing process.

[0014] Preferably, the preparation method of the grafted wood fiber is as follows:

[0015] Step A1: Add wood fiber into a mixed solution of toluene, acetone and methanol, extract for 5 - 7 h, heat up to 90 - 110°C, and dry for 22 - 26 h to obtain purified wood fiber;

[0016] Step A2: Add the purified wood fiber into a pyridine solution, then add undecynoic acid, stir evenly, heat up to 110 - 120°C, react for 2 - 4 h, and after the reaction is completed, obtain esterified wood fiber;

[0017] Step A3: Add the esterified wood fiber into a toluene solvent, add initiator benzoyl peroxide, styrene propylene containing a silicon alkane long-chain flame retardant and styrene propylene containing a silicon alkane antibacterial agent, stir and mix, heat up to 90 - 110°C, react for 2 - 4 h, and filter to obtain grafted wood fiber.

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

[0019] In Step A2, the mass ratio of the purified wood fiber to undecynoic acid is 1:2.5 - 3;

[0020] In step A3, the mass ratio of the esterified lignocellulose, initiator, styrene propylene with a long-chain silane-based flame retardant, and styrene propylene with a silane-based antibacterial agent is 1: 0.06 - 0.12: 8.5 - 17.2: 4.75 - 9.55.

[0021] Preferably, the preparation method of the styrene propylene with a long-chain silane-based flame retardant is as follows:

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

[0023] Step B2: Under a nitrogen atmosphere, add intermediate 1 to 1-thiophospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2,2,2]octane, heat up to 90 - 110 °C, fractionally distill and react for 1 - 3 h, then heat up to 130 - 150 °C, fractionally distill and react for 4 - 6 h. After the reaction is completed, the styrene propylene with a long-chain silane-based flame retardant is obtained.

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

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

[0026] Preferably, the preparation method of the styrene propylene with a silane-based antibacterial agent is as follows:

[0027] Step C1: Add phosphonium tetrakis(hydroxymethyl)sulfate to diethylene glycol dimethyl ether solvent, heat up to 20 - 25 °C, add 3-(trichlorosilyl)-1-propylamine, heat up to 50 - 60 °C, react for 50 - 70 min, heat up to 120 - 140 °C, react for 8 - 10 h, cool, crystallize, and filter to obtain a cage-like quaternary phosphonium salt organosilicate;

[0028] Step C2: Add paraformaldehyde to chloroform solvent, then add CaH2, heat up to 20 - 30 °C, react for 20 - 40 min, heat up to 50 - 70 °C, add the cage-like quaternary phosphonium salt organosilicate, then heat up to 75 - 95 °C, add 5-(2-propenyl)-1,3-benzenediol, and react for 50 - 70 min to obtain the styrene propylene with a silane-based antibacterial agent.

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

[0030] In step C2, the mass ratio of paraformaldehyde, CaH2, cage-like quaternary phosphonium salt organosilicate, and 5-(2-propenyl)-1,3-benzenediol is 1:1.0 - 1.1:4.2 - 4.3:1.1 - 1.3.

[0031] Preferably, the preparation method of the triazine-modified isocyanate adhesive is as follows:

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

[0033] Step D2: Under a nitrogen atmosphere, add toluene-2,4-diisocyanate, polyethylene glycol 400, and the triazine-containing polyol to a three-necked flask, stir and mix evenly, heat up to 80 - 90°C, react for 2 - 4 h, cool down to 35 - 55°C, add dimethylolpropionic acid and 1,4-butanediol, heat up to 70 - 90°C, react for 30 - 90 min, cool down to 35 - 50°C, add the catalysts dibutyltin dilaurate and stannous octoate, heat up to 60 - 80°C, react for 3 - 5 h. After the reaction is completed, cool down to 30 - 50°C, add the stabilizer triphenyl phosphate, and dilute with ethyl acetate to obtain the triazine-modified isocyanate adhesive.

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

[0035] In step D2, the mass ratio of toluene-2,4-diisocyanate, polyethylene glycol 400, the triazine-containing polyol, dimethylolpropionic acid, 1,4-butanediol, dibutyltin dilaurate, stannous octoate, and triphenyl phosphate 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] Advantages of the present invention:

[0037] The present invention provides an environmentally friendly moisture-proof medium density fiberboard and a preparation method thereof. By combining natural renewable raw materials with innovative materials, and integrating refined process control and multifunctional design, compared with the prior art, the present invention significantly reduces the environmental load, improves the moisture resistance and damp-proof ability, while taking into account the flame retardant and antibacterial properties, and optimizes the structural stability. It can be widely used in furniture manufacturing, building decoration and high humidity environment scenarios, and has a green and sustainable application prospect with high adaptability. Detailed Embodiments

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

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

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

[0041] S2: Under a nitrogen atmosphere, add 140 g of Intermediate 1 to 100 g of 1-mercapto-phospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2,2,2]octane, heat up to 90 °C, carry out fractional distillation reaction for 3 h, then heat up to 130 °C, carry out fractional distillation reaction for 6 h, and after the reaction is completed, obtain styrene propylene containing a silane long chain flame retardant.

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

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

[0044] S2: Under a nitrogen atmosphere, add 145 g of Intermediate 1 to 100 g of 1-mercapto-phospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2,2,2]octane, heat up to 100 °C, carry out fractional distillation reaction for 2 h, then heat up to 140 °C, carry out fractional distillation reaction for 5 h, and after the reaction is completed, obtain styrene propylene containing a silane long chain flame retardant.

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

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

[0047] S2: Under a nitrogen atmosphere, add 150 g of Intermediate 1 into 100 g of 1-thiophospha-4-hydroxymethyl-2,6,7-trioxabicyclo[2,2,2]octane, heat up to 110 °C, fractionate and react for 1 h, then heat up to 150 °C, fractionate and react for 4 h. After the reaction is completed, obtain styrene propylene with a silane long-chain flame retardant.

[0048] Example 4: The preparation method of styrene propylene with a silane antibacterial property is as follows:

[0049] S1: Add 100 g of phosphonium tetramethylsulfate into 200 mL of diethylene glycol dimethyl ether solvent, heat up to 20 °C, add 85 g of 3-(trichlorosilyl)-1-propylamine, heat up to 50 °C, react for 70 min, heat up to 120 °C, react for 10 h, cool, crystallize, filter to obtain a cage-shaped quaternary phosphonium salt organosilicate;

[0050] S2: Add 100 g of paraformaldehyde into 200 mL of chloroform solvent, then add 100 g of CaH2, heat up to 20 °C, react for 40 min, heat up to 50 °C, add 420 g of the cage-shaped quaternary phosphonium salt organosilicate, then heat up to 75 °C, add 110 g of 5-(2-propenyl)-1,3-benzenediol, react for 70 min to obtain styrene propylene with a silane antibacterial property.

[0051] Example 5: The preparation method of styrene propylene with a silane antibacterial property is as follows:

[0052] S1: Add 100 g of phosphonium tetramethylsulfate into 200 mL of diethylene glycol dimethyl ether solvent, heat up to 22 °C, add 90 g of 3-(trichlorosilyl)-1-propylamine, heat up to 55 °C, react for 60 min, heat up to 130 °C, react for 9 h, cool, crystallize, filter to obtain a cage-shaped quaternary phosphonium salt organosilicate;

[0053] S2: Add 100 g of paraformaldehyde into 200 mL of chloroform solvent, then add CaH2, heat up to 25 °C, react for 30 min, heat up to 60 °C, add 420 g of the cage-shaped quaternary phosphonium salt organosilicate, then heat up to 80 °C, add 120 g of 5-(2-propenyl)-1,3-benzenediol, react for 60 min to obtain styrene propylene with a silane antibacterial property.

[0054] Example 6: The preparation method of styrene propylene with a silane antibacterial property is as follows:

[0055] S1: Add 100 g of tetrakis(hydroxymethyl)phosphonium sulfate to 200 mL of diethylene glycol dimethyl ether solvent, heat up to 25 °C, add 95 g of 3-(trichlorosilyl)-1-propylamine, heat up to 50 °C, react for 70 min, then heat up to 120 °C and react for 10 h. Cool and crystallize, then filter to obtain cage-shaped quaternary phosphonium salt organosilicate.

[0056] S2: Add 100 g of paraformaldehyde to 200 mL of chloroform solvent, then add 110 g of CaH2, heat up to 30 °C, react for 20 min, heat up to 70 °C, add 430 g of cage-shaped quaternary phosphonium salt organosilicate, then heat up to 95 °C, add 130 g of 5-(2-propenyl)-1,3-benzenediol, and react for 50 min to obtain silane-containing antibacterial styrene propylene.

[0057] Example 7: The preparation method of grafted wood fiber is as follows:

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

[0059] S2: Add 100 g of purified wood fiber to 100 mL of pyridine solution, then add 250 g of undecynoic acid, stir evenly, heat up to 110 °C and react for 4 h. After the reaction is completed, obtain esterified wood fiber.

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

[0061] Example 8: The preparation method of grafted wood fiber is as follows:

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

[0063] S2: Add 100 g of purified wood fiber to 100 mL of pyridine solution, then add 280 g of undecynoic acid, stir evenly, heat up to 115 °C and react for 3 h. After the reaction is completed, obtain esterified wood fiber.

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

[0065] Example 9: The preparation method of grafted wood fiber is as follows:

[0066] S1: Add 100 g of wood fiber into a mixed solution of 42 mL of toluene, 12 mL of acetone and 10 mL of methanol, extract for 7 h, heat up to 90 °C, dry for 26 h to obtain purified wood fiber;

[0067] S2: Add 100 g of purified wood fiber into 100 mL of pyridine solution, then add 300 g of undecynoic acid, stir evenly, heat up to 120 °C, react for 2 h, after the reaction is completed, obtain esterified wood fiber;

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

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

[0070] S1: Add 100 g of cyanuric chloride into 100 mL of acetone solvent, add 240 g of 5-amino-1,3-dihydroxytoluene, heat up to 10 °C, react for 40 min, then heat up to 70 °C, reflux and react for 2 h, after the reaction is completed, obtain polyol containing triazine;

[0071] S2: Under a nitrogen atmosphere, add 280 g of toluene-2,4-diisocyanate, 150 g of polyethylene glycol 400, 100 g of polyol containing triazine into a three-necked flask, stir and mix evenly, heat up to 80 °C, react for 4 h, cool down to 35 °C, add 26 g of dimethylolpropionic acid and 28 g of 1,4-butanediol, heat up to 70 °C, react for 90 min, cool down to 35 °C, add 10 g of catalyst dibutyltin dilaurate and 11 g of stannous octoate, heat up to 60 °C, react for 5 h, after the reaction is completed, cool down to 30 °C, add 0.2 g of stabilizer triphenyl phosphate, dilute 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 100 g of cyanuric chloride to 100 mL of acetone solvent, add 245 g of 5-amino-1,3-dihydroxytoluene, heat up to 15 °C, react for 30 min, then heat up to 60 °C and reflux for 2.5 h. After the reaction is completed, a triazine-containing polyol is obtained.

[0074] S2: Under a nitrogen atmosphere, add 300 g of toluene-2,4-diisocyanate, 160 g of polyethylene glycol 400, and 100 g of the triazine-containing polyol to a three-necked flask, stir and mix evenly, heat up to 85 °C, react for 3 h, cool down to 40 °C, add 28 g of dimethylolpropionic acid and 30 g of 1,4-butanediol, heat up to 80 °C, react for 60 min, cool down to 40 °C, add 11 g of the catalyst dibutyltin dilaurate and 12 g of stannous octoate, heat up to 70 °C, react for 4 h. After the reaction is completed, cool down to 40 °C, add 0.5 g of the stabilizer triphenyl phosphate, and dilute with ethyl acetate to obtain a triazine-modified isocyanate adhesive.

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

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

[0077] S2: Under a nitrogen atmosphere, add 320 g of toluene-2,4-diisocyanate, 170 g of polyethylene glycol 400, and 100 g of the triazine-containing polyol to a three-necked flask, stir and mix evenly, heat up to 90 °C, react for 2 h, cool down to 55 °C, add 29 g of dimethylolpropionic acid and 32 g of 1,4-butanediol, heat up to 90 °C, react for 30 min, cool down to 50 °C, add 12 g of the catalyst dibutyltin dilaurate and 13 g of stannous octoate, heat up to 80 °C, react for 3 h. After the reaction is completed, cool down to 50 °C, add 1 g of the stabilizer triphenyl phosphate, and dilute with ethyl acetate to obtain a triazine-modified isocyanate adhesive.

[0078] Example 13: The preparation method of an environmentally friendly moisture-proof density board is as follows:

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

[0080] S2: Put the mixed fibers into a multi-roll pre-press, heat up to 20°C, apply a pressure of 2 MPa, pre-press for 10 min, take out, put into a multi-layer hot press, heat up to 200°C, apply a pressure of 3 MPa, extrude for 18 min, then reduce the pressure to 0.5 MPa, cool down to 170°C, hold for 1 min, finish hot pressing, cool down to 50°C, and cool for 20 min to obtain an environmentally friendly moisture-proof density board.

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

[0082] S1: Add 600 g of modified wood fibers and 400 g of bamboo fibers into a blender, then add 100 g of modified isocyanate adhesive, 20 g of nano-silica, 5 g of vegetable oil release agent and 1 g of curing agent ammonium chloride, rotate at 1000 rpm, stir for 4 min, after stirring is completed, dry to obtain mixed fibers;

[0083] S2: Put the mixed fibers into a multi-roll pre-press, heat up to 25°C, apply a pressure of 1.5 MPa, pre-press for 13 min, take out, put into a multi-layer hot press, heat up to 190°C, apply a pressure of 4 MPa, extrude for 16 min, then reduce the pressure to 0.75 MPa, cool down to 165°C, hold for 1.6 min, finish hot pressing, cool down to 40°C, and cool for 25 min to obtain an environmentally friendly moisture-proof density board.

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

[0085] S1: Add 700 g of modified wood fibers and 500 g of bamboo fibers into a blender, then add 150 g of modified isocyanate adhesive, 30 g of nano-silica, 10 g of vegetable oil release agent and 1.5 g of curing agent ammonium chloride, rotate at 1200 rpm, stir for 3 min, after stirring is completed, dry to obtain mixed fibers;

[0086] S2: Put the mixed fibers into a multi-roll pre-press, heat up to 30°C, apply a pressure of 1 MPa, pre-press for 15 min, take out, put into a multi-layer hot press, heat up to 180°C, apply a pressure of 5 MPa, extrude for 12 min, then reduce the pressure to 1 MPa, cool down to 160°C, hold for 2 min, finish hot pressing, cool down to 30°C, and cool for 30 min to obtain an environmentally friendly moisture-proof density board.

[0087] Comparative Example 1:

[0088] In this comparative example, compared with Example 13, nano-silica was not added during the preparation process of the environmentally friendly moisture-proof density board, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally an environmentally friendly moisture-proof density board was obtained.

[0089] Comparative Example 2:

[0090] In this comparative example, compared with Example 13, only the "triazine-modified isocyanate adhesive" is replaced with "isocyanate adhesive", and the remaining steps and parameters are the same. This comparative example will not be repeated here, and finally an environmentally friendly moisture-proof density board is obtained.

[0091] Comparative Example 3:

[0092] In this comparative example, compared with Example 13, only the "styrene propylene with silane long-chain flame retardant" is replaced with "styrene propylene", and the remaining steps and parameters are the same. This comparative example will not be repeated here, and finally an environmentally friendly moisture-proof density board is obtained.

[0093] Comparative Example 4:

[0094] In this comparative example, compared with Example 13, only the "bamboo fiber" is replaced with "wood fiber", and the remaining steps and parameters are the same. This comparative example will not be repeated here, and finally an environmentally friendly moisture-proof density board is obtained.

[0095] Comparative Example 5:

[0096] In this comparative example, compared with Example 13, only the "styrene propylene with silane antibacterial" is replaced with "styrene", and the remaining steps and parameters are the same. This comparative example will not be repeated here, and finally an environmentally friendly moisture-proof density board is obtained.

[0097] Performance test:

[0098] Formaldehyde release detection:

[0099] 1. Referring to the test standard of GB / T 17657-2013, a 0.225 m 2 climatic chamber, equipped with an air purification system, a temperature and humidity control system, a ventilation control system, etc.; a two-channel atmospheric sampler QC-2 type; a high-performance liquid chromatograph HPLC, Shanghai Tianmei Techcomp LC-2130 type; a chromatographic column: SUPELCOSIL CTM LC—l8 column, 250 mm × 4.6 mm, 5 μm;

[0100] 2. Detection conditions in the small climatic chamber: temperature: 23°C ± 0.5°C; relative humidity: 50% ± 3‰; air change rate: 0.65 times / h; loading rate: 1:lm 2 / m 3 . Take 2 density boards each from Examples 13 - 15 and Comparative Examples 1 - 5, with sizes of 300 mm × 300 mm × 18 mm and 1300 mm × 75 mm × 18 mm respectively;

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

[0102] 4. Evaluation index: The formaldehyde release amount is required to be ≤ 0.03 mg / m 3 , better than the E0 standard (≤ 0.05 mg / m 3 );

[0103] VOC Emission Detection

[0104] 1. Refer to the ISO16000-6 test standard, use a gas chromatograph CC-FID, Shanghai Tianmei (GC-7900); chromatographic column: SE-30 quartz capillary chromatographic column, 50m x 0.25min x 0.1μm;

[0105] 2. Analyze the total volatile organic compounds TVOC of the board. Respectively take the density boards of Examples 13 - 15 and Comparative Examples 1 - 5, and collect the gas after balancing in a closed cabin 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 Detection

[0109] Refer to the GB / T 17657-2013 test standard. Respectively take the density boards of Examples 13 - 15 and Comparative Examples 1 - 5 and place them under the conditions of temperature (20 ± 2)°C and relative humidity (65 ± 5)% until the mass is constant. Measure the thickness h1 of the center point of the specimen with an accuracy of 0.01 mm, and the measurement point is at the intersection of the diagonals of the specimen; then place it in a constant temperature water bath at (20 ± 2)°C, soak for 24 hours respectively, then take out the specimen, wipe off the attached water on the surface, and measure its thickness h2 at the original measurement point with an accuracy of 0.01 mm; the TS of the specimen is calculated according to the following formula:

[0110] Long-term Moisture Resistance Test

[0111] 1. Refer to the ASTM D1037 test standard, use a thermo-hygrostat, temperature 38 ± 1°C, humidity 90 ± 2%. Respectively take the density boards of Examples 13 - 15 and Comparative Examples 1 - 5, cut them into standard sizes of 300 mm × 300 mm × 18 mm, and take 3 samples;

[0112] 2. Place the sample horizontally on a non-hygroscopic support with a spacing of ≥50 mm. Avoid contact with the chamber wall or other samples and keep for 7 days at 38°C and 90% humidity to simulate a long-term high-humidity environment.

[0113] 3. Calculate the formula for the thickness change rate:

[0114] Where: T1-----Before testing, measure the thickness at the measurement point, in mm;

[0115] T2-----After testing, measure the thickness at the measurement 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 retardancy test

[0121] Refer to the test standard of GB / T 2406.2, use the limiting oxygen index instrument HC-2C to measure the limiting oxygen index, and conduct the determination and analysis of the combustion performance of Examples 13 - 15 and Comparative Examples 1 - 5, and take the average of five measurement results.

[0122] Vertical burning test

[0123] Refer to the UL94 V-0 test standard. Prepare samples of the density boards of Examples 13 - 15 and Comparative Examples 1 - 5 according to the standard size of 125 mm × 13 mm × 3 mm, hang them vertically in the combustion chamber, and record the burning time and the situation of the dropped objects igniting the cotton wool.

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

[0125]

[0126]

[0127] Antibacterial property test: Refer to the ISO 22196 test standard;

[0128] Directly drop the experimental bacterial liquid onto the density boards of Examples 13 - 15 and Comparative Examples 1 - 5 respectively, allow the bacteria to fully contact and expose on the density board for a certain time, then cover with a culture medium to allow the remaining bacteria to grow. Compare the percentage decrease in the amount of bacteria on the antibacterial samples to judge their antibacterial ability.

[0129] Use a magnifying glass to count the colony forming units. The operating steps are as follows:

[0130] 1. Bacterial liquid preparation: Take a fresh broth culture of Escherichia coli for 24 hours, shake well and let stand for 20 minutes, and dilute it into a bacterial liquid with a bacterial count of 105 - 106 CFU / mL;

[0131] 2. Bacterial infection: Put the samples of Examples 13 - 15 and Comparative Examples 1 - 5 with a size of 5.0 cm × 5.0 cm into a sterile petri dish with a diameter of 9 cm, evenly drop 1.5 mL of the bacterial liquid, so that it is evenly distributed on the sample and completely absorbed. Repeat 6 pieces for each sample, and place them in an incubator at 37°C to dry for 1 hour;

[0132] 3. Place the dried and bacterially infected sample flat on the surface of the nutrient agar plate, and then evenly cover the surface of the bacterially infected sample with semi-solid nutrient agar with an appropriate thickness. Place it in an incubator at 37% for 48 hours, and set up a blank control group;

[0133] 4. Observe the results: Drop the safranin staining solution on the above semi-solid nutrient agar for staining for 1 hour. Use a magnifying glass to count the number of colonies on each cloth sample, calculate the average value of the number of colonies on 6 cloth samples and record it;

[0134] 5. Calculate the antibacterial rate: Repeat the above experiment 3 times, take the average value and calculate the antibacterial rate using the following formula:

[0135]

[0136] In the formula: A is the average number of colonies on the control cloth sample;

[0137] B is the average number of colonies on the antibacterial cloth sample.

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

[0139] Project A (CFU / mL) B (CFU / mL) Bacteriostatic 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 test standard of GB / T 17657 - 2013, use a universal testing machine. Take the samples of Examples 13 - 15 and Comparative Examples 1 - 5 respectively, cut them into 50 mm × 50 mm × 20 mm, apply pressure, and record the maximum load, unit MPa.

[0142] Internal bond strength

[0143] Take the samples of Examples 13 - 15 and Comparative Examples 1 - 5 respectively, cut the samples into 50 mm × 50 mm, and test the interlayer peel strength through a tensile machine, unit 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 Table 1-5, the environmentally friendly moisture-proof density board prepared by the present invention has ultra-low formaldehyde and TVOC release amounts, better moisture-proof performance, high flame retardancy, good antibacterial function and excellent mechanical properties.

[0148] In Comparative Example 1, due to the absence of nano-silica, the TS and ΔT increased significantly, the moisture-proof performance decreased, and at the same time, the VOC release amount increased. The reason is that nano-silica fills the microscopic pores by uniformly dispersing between fibers, reducing the moisture penetration path, and at the same time enhancing the interfacial bonding force between fibers and adhesives. After the absence, the porosity inside the board increases, the hygroscopic swelling intensifies, and the uneven distribution of adhesives leads to an increase in the release of volatile organic compounds.

[0149] In addition, the maximum load and interlayer peeling strength of Comparative Example 1 decreased. The reason is that nano-silica not only fills the pores but also disperses as a reinforcing phase in the adhesive to enhance the interfacial bonding force between fibers and adhesives. The absence in Comparative Example 1 leads to a weakening of the mechanical interlocking effect between the adhesive and the fibers, a reduction in the stress transfer efficiency, and a significant decrease in the compressive strength and interlayer bonding strength. Another possible reason is that the absence of nanoparticles may affect the rheological properties of the adhesive, resulting in uneven mixing and the formation of local weak regions after curing, further weakening the overall structural compactness.

[0150] In Comparative Example 2, since the triazine-modified adhesive was replaced with a common isocyanate adhesive, the formaldehyde release amount exceeded the standard, the LOI decreased, and the vertical burning grade was not passed. At the same time, the compressive strength decreased significantly. The reason is that the triazine-modified adhesive provides a high crosslinking density through the triazine ring structure, reducing formaldehyde release and enhancing heat resistance. The common adhesive has a low crosslinking degree, weak interfacial bonding force, and lacks flame retardant groups, resulting in a comprehensive decline in environmental protection, flame retardancy, and mechanical properties.

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

[0152] In Comparative Example 3, since the silane long-chain flame-retardant styrene-propylene was not used, the LOI was the lowest, and the vertical burning did not meet the standard. In addition, the flame retardancy was almost completely lost. The reason is that the silane long-chain flame-retardant styrene-propylene forms a dense carbon layer through the phosphorus-silicon synergistic effect during combustion to isolate oxygen and inhibit flame spread. After the absence of this component, the density board cannot form an effective flame-retardant barrier, resulting in an accelerated burning rate.

[0153] In addition, the maximum load and interlaminar peel strength of Comparative Example 3 decreased. The reason is that the silyl groups in the silane long-chain flame-retardant styrene-propylene can form chemical bonds with the fiber surface through hydrolysis and condensation, enhancing the interfacial bonding between the fiber and the adhesive. After the absence, the surface activity of the fiber decreases, and the adhesive only physically coats the fiber, weakening the interfacial bonding force. Another possible reason is that the absence of the flame retardant may cause the material to soften at high temperature during the hot pressing process, reducing the contact area between the fiber and the adhesive and further weakening the structural stability.

[0154] In Comparative Example 4, since the bamboo fiber was replaced with wood fiber, the TS and ΔT increased, and the antibacterial rate decreased. The reason is that bamboo fiber naturally has a hollow structure and antibacterial components such as bamboo kun, which cooperate with the grafted wood fiber to form a hydrophobic-antibacterial network. At the same time, wood fiber has strong hygroscopicity and lacks antibacterial activity, resulting in the simultaneous deterioration of moisture-proof and antibacterial properties.

[0155] In addition, the maximum load and interlaminar peel strength of Comparative Example 3 decreased. The reason is that bamboo fiber has a natural hollow structure and a higher length-to-diameter ratio, which can provide better mechanical support. It is similar to the reinforcing phase of natural composites. While wood fiber has a dense structure but higher brittleness, resulting in a decrease in compressive strength and interlaminar strength. Moreover, the polar groups (such as hydroxyl groups) on the surface of bamboo fiber are more likely to react with the adhesive, 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 and swelling 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 delamination.

[0156] In Comparative Example 5, since the silane antibacterial styrene-propylene was replaced with styrene, the bacteriostatic rate decreased. The reason is that the cage-like quaternary phosphonium organosilicate in the silane antibacterial styrene-propylene can slowly release antibacterial ions and damage the microbial cell membrane, and styrene has no antibacterial function and may cause bacteria to attach and breed due to insufficient hydrophobicity.

[0157] In addition, for Comparative Example 3, the maximum load and the interlayer peeling strength decreased. The reason is that the silyl groups in the silane-containing antibacterial styrene-propylene participated in the fiber surface grafting reaction, forming chemical bonds to enhance the interfacial bonding; while styrene was only physically blended and could not provide chemical bonding, resulting in a significant decrease in the interlayer peeling strength. Moreover, the introduction of styrene might interfere with the curing process of the adhesive, forming an uneven crosslinked network and reducing the compressive strength. Another possible reason is that styrene has poor hydrophobicity, which may lead to uneven distribution of the adhesive on the fiber surface, enrichment or depletion of the adhesive in local areas, forming stress concentration points and further weakening the mechanical properties.

[0158] Those of ordinary skill 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 present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

[0159] The present invention aims 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 the present invention shall be included within the protection scope of the present invention.

Claims

1. An environmentally friendly moisture-proof density board, characterized in that: The invention comprises the following components in parts by weight: 50-70 parts of modified wood fiber, 30-50 parts of bamboo fiber, 8-15 parts of modified isocyanate adhesive, 0.5-3 parts of nano silicon dioxide, 0.3-1 parts of vegetable oil release agent and 0.08-0.15 parts of curing agent.

2. A method for preparing an environmentally friendly moisture-proof density board, characterized in that: The preparation method is as follows: Step S1: adding modified wood fiber and bamboo fiber into a mixer, and then adding modified isocyanate adhesive, nano-silicon dioxide, vegetable oil release agent and curing agent ammonium chloride, rotating speed 800-1200rpm, stirring for 3-5min, and drying after stirring to obtain mixed fiber; Step S2: putting the mixed fiber into a multi-roller pre-pressing machine, heating it to 20-30°C, pressing it to 1-2MPa, pre-pressing it for 10-15min, taking it out, putting it into a multi-layer hot press, heating it to 180-200°C, pressing it to 3-5MPa, pressing it for 12-18min, then reducing the pressure to 0.5-1MPa, reducing the temperature to 160-170°C, continuing for 1-2min, and ending the hot pressing, reducing the temperature to 30-50°C, cooling it for 20-30min, and obtaining an environmentally friendly moisture-proof density board; The modified wood fiber is a grafted wood fiber; The modified isocyanate adhesive is a triazine modified isocyanate adhesive.

3. The method for preparing the environmentally friendly moisture-proof density board according to claim 2, characterized in that: The grafted wood fiber is prepared by the following method: Step A1: adding wood fiber into a mixed solution of toluene, acetone and methanol, extracting for 5-7 hours, heating to 90-110° C., and drying for 22-26 hours to obtain purified wood fiber; Step A2: Add the purified wood fiber to the pyridine solution, then add undecynoic acid, stir evenly, heat to 110-120° C., react for 2-4 hours, and the reaction is completed to obtain esterified wood fiber; Step A3: Add the esterified wood fiber to toluene solvent, add initiator benzoyl peroxide, styrene containing silane long-chain flame retardant and styrene containing silane antibacterial, stir and mix, heat to 90-110° C., react for 2-4 hours, filter, and obtain grafted wood fiber.

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

55.

5. The method for preparing the environmentally friendly moisture-proof density board according to claim 3, characterized in that: The preparation method of the silane long-chain flame-retardant styrene is as follows: Step B1: Add paraformaldehyde to chloroform solvent, then add CaH2, heat to 20-30°C, react for 20-40 min, heat to 50-70°C, add 11-aminoundecyltrimethoxysilane, then heat to 75-95°C, add 5-(2-propenyl)1,3-benzenediol, react for 50-70 min to obtain intermediate 1; Step B2: Under nitrogen environment, add intermediate 1 to 1-thiophospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane, heat to 90-110°C, and react by fractionation for 1-3h, then heat to 130-150°C, and react by fractionation for 4-6h. After the reaction is completed, styrene containing silane long-chain flame retardant is obtained.

6. The method for preparing the environmentally friendly moisture-proof density board according to claim 5, characterized in that: 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; The mass ratio of the intermediate 1 to 1-sulfanylphospha-4-hydroxymethyl 2,6,7-trioxabicyclo[2,2,2]octane in step B2 is 1.4-1.5:

1.

7. The method for preparing the environmentally friendly moisture-proof density board according to claim 3, characterized in that: The preparation method of the silane-containing antibacterial styrene is as follows: Step C1: adding tetrakis(hydroxymethyl)phosphonium sulfate to diethylene glycol dimethyl ether solvent, heating to 20-25° C., adding 3-(trichlorosilyl)-1-propylamine, heating to 50-60° C., reacting for 50-70 min, heating to 120-140° C., reacting for 8-10 h, cooling, crystallizing, filtering, and obtaining a caged quaternary phosphonium salt organosilicate; Step C2: Add paraformaldehyde to chloroform solvent, then add CaH2, heat to 20-30°C, react for 20-40min, heat to 50-70°C, add caged quaternary phosphonium salt organic silicate, then heat to 75-95°C, add 5-(2-propenyl)1,3-benzenediol, react for 50-70min, and obtain silane-containing antibacterial phenylpropene.

8. The method for preparing the environmentally friendly moisture-proof density board according to claim 7, characterized in that: The mass ratio of tetrakis(hydroxymethyl)phosphonium sulfate to 3-(trichlorosilyl)-1-propylamine in step C1 is 1:0.85-0.95; The mass ratio of the polyformaldehyde, CaH2, caged quaternary phosphonium salt organic silicate and 5-(2-propenyl)1,3-benzenediol in step C2 is 1:1.0-1.1:4.2-4.3:1.1-1.

3.

9. The method for preparing the environmentally friendly moisture-proof density board according to claim 2, characterized in that: The triazine-modified isocyanate adhesive is prepared as follows: Step D1: Add cyanuric chloride to an acetone solvent, add 5-amino-1,3-dihydroxytoluene, raise the temperature to 10-20°C, react for 20-40 minutes, then raise the temperature to 50-70°C, reflux for 2-3 hours, and complete the reaction to obtain a triazine-containing polyol; Step D2: Under a nitrogen environment, add toluene-2,4-diisocyanate, polyethylene glycol 400, and triazine-containing polyol into a three-necked flask, stir and mix evenly, heat to 80-90°C, react for 2-4h, cool to 35-55°C, add dimethylolpropionic acid and 1,4-butanediol, heat to 70-90°C, react for 30-90min, cool to 35-50°C, add catalysts dibutyltin dilaurate and stannous octoate, heat to 60-80°C, react for 3-5h, the reaction is completed, cool to 30-50°C, add stabilizer triphenyl phosphate, dilute with ethyl acetate, and obtain a triazine-modified isocyanate adhesive.

10. The method for preparing the environmentally friendly moisture-proof density board according to claim 9, characterized in that: The mass ratio of cyanuric chloride to 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, 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.

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