Moisture-proof mildew-resistant medium-density lightweight fiberboard

Abstract

The application discloses a kind of damp-proof mildew-resistant medium-density fiberboard, belong to medium-density fiberboard technical field, will be prepared into fiber slurry after wood fiber is hotly ground and defibered, add modified chitosan solution, melamine modified urea-formaldehyde resin, ammonium chloride curing agent and mildew-proof agent powder to fiber slurry, stir and mix, dry to the moisture content of fiber is 7-8%, lay to mould, under the condition of 195-200 DEG C and 5-6MPa hot-press 5-6min, obtain damp-proof mildew-resistant medium-density fiberboard;Mildew-proof agent powder is with four acicular zinc oxide whisker as matrix, after self-polymerization of tridecafluoro octyl trimethoxysilane monomer, four acicular zinc oxide whisker is coated, and the fluorine side chain on its surface helps to improve the moisture-proof performance of medium-density fiberboard;Modified chitosan solution contains disulfide bond, can be crosslinked with the hydroxyl group on the surface of wood fiber, help to improve wood fiber strength and antibacterial property.

Description

Technical Field

[0001] This invention belongs to the field of medium-density fiberboard technology, specifically relating to a moisture-proof and mildew-resistant medium-density lightweight fiberboard. Background Technology

[0002] Medium-density fiberboard (MDF) is a commonly used board material in many fields such as furniture manufacturing, building decoration, and vehicle and ship interior decoration. MDF uses wood fibers or other plant fibers as raw materials, mainly including pine, poplar, eucalyptus, bamboo, reeds, etc. These raw materials are mechanically separated and chemically treated to form wood chips or fibers, which are then mixed with adhesives, waterproofing agents, and other auxiliary materials, and manufactured into boards under heat and pressure.

[0003] Medium-density fiberboard (MDF) is highly absorbent and easily becomes damp and moldy. Even if waterproofing agents and other auxiliary materials are added during the manufacturing process, the surface waterproofing agent will be lost and depleted after long-term use, making the fiberboard still susceptible to dampness and mold. Summary of the Invention

[0004] The purpose of this invention is to provide a moisture-proof and mildew-resistant medium-density lightweight fiberboard, which improves its water resistance and mildew resistance by using mildew-resistant powder and modified chitosan solution, thereby extending its service life.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A moisture-proof and mildew-resistant medium-density fiberboard is prepared through the following steps:

[0007] Wood fibers are thermally ground to produce fiber slurry. Modified chitosan solution, melamine-modified urea-formaldehyde resin, ammonium chloride curing agent, and mildew inhibitor powder are added to the fiber slurry. The mixture is stirred and mixed for 20-30 minutes at 20-25℃ and 500-800 r / min. The mixture is then dried until the fiber moisture content is 7-8%. The mixture is laid into a mold and hot-pressed for 5-6 minutes at 195-200℃ and 5-6 MPa to obtain a moisture-proof and mildew-resistant medium-density lightweight fiberboard.

[0008] Furthermore, the ratio of wood fiber, modified chitosan solution, melamine-modified urea-formaldehyde resin, ammonium chloride curing agent, and antifungal powder is 100g: 50-60mL: 13-13.5g: 0.03325-0.03375g: 0.06-0.08g.

[0009] Furthermore, the antifungal powder is prepared through the following steps:

[0010] Deionized water, tetrahydrofuran, tetraneedle-shaped zinc oxide whiskers, and tetramethylammonium hydroxide were added to the reactor at 20-25℃. The mixture was stirred at 2000-3000 r / min for 10-15 min. Then, under nitrogen protection, tridecafluorooctyltrimethoxysilane monomer was added to the reactor. After stirring for another 5-10 min, the mixture was stirred at 35℃ for 24-26 h to allow the polymerized fluorinated polysilsesquioxane to coat the tetraneedle-shaped zinc oxide whiskers. The solvent and unreacted monomers were removed by rotary evaporation. The reaction product was washed 2-3 times with anhydrous ethanol and deionized water, respectively, and then vacuum dried to obtain the antifungal agent powder.

[0011] Furthermore, the mass ratio of deionized water, tetrahydrofuran, tetraneedle-shaped zinc oxide whiskers, tetramethylammonium hydroxide, and tridecafluorooctyltrimethoxysilane monomer is 5:15:5-6:0.05:15-16.

[0012] Furthermore, the modified chitosan was prepared through the following steps:

[0013] Chitosan and deionized water are added to a reaction vessel, and the pH value is adjusted to 3 with acetic acid solution with a molar concentration of 1 mol / L. The mixture is stirred at 300-500 r / min for 20-30 min. Then, a modifier solution and anhydrous ethanol as a desiccant are added to the reaction vessel, and the mixture is stirred and reacted at 20-25℃ for 16-18 h to obtain a modified chitosan solution.

[0014] Furthermore, the ratio of chitosan, deionized water, and modifier solution is 3.2g:160mL:40mL:15-20mL.

[0015] Furthermore, the modifier solution is prepared by the following steps:

[0016] Add α-lipoic acid, sodium hydroxide and deionized water to a reaction vessel and stir at 200-300 r / min for 30-40 min. Then add EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) to the reaction vessel and continue stirring for 5-10 min to activate the carboxyl group in lipoic acid and obtain the modifier solution.

[0017] Furthermore, the ratio of α-lipoic acid, sodium hydroxide, deionized water, EDC and MHS is 0.2g:0.04g:40mL:0.096g:0.115g.

[0018] The beneficial effects of this invention are:

[0019] The moisture-proof and mildew-resistant medium-density fiberboard of this invention has good waterproof effect and can maintain a high mildew resistance level after being immersed in water, which helps to extend the service life of the medium-density fiberboard.

[0020] The antifungal powder of this invention uses tetraneedle-shaped zinc oxide whiskers as a matrix. Its nano-semiconductor activity allows it to release active oxygen, exhibiting a highly efficient, broad-spectrum, and long-lasting antibacterial effect on a macroscopic scale. The tetraneedle-shaped zinc oxide whiskers are coated by the self-polymerization of tridecafluorooctyltrimethoxysilane monomer, and the fluorinated side chains on its surface help improve the moisture-proof performance of medium-density fiberboard (MDF). The modified chitosan solution is prepared by dehydration condensation of the carboxyl groups on the octyl sulfuric acid in the modifier solution and the amino groups on the chitosan, producing chitosan containing disulfide bonds. This chitosan can crosslink with the hydroxyl groups on the surface of wood fibers, helping to improve the strength and antibacterial properties of the wood fibers, further enhancing the antifungal effect of MDF. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: This example provides a moisture-proof and mildew-resistant medium-density fiberboard, which is prepared through the following steps:

[0023] Step 1: Add 50 kg of deionized water, 150 kg of tetrahydrofuran, 50 kg of tetraneedle-shaped zinc oxide whiskers, and 0.5 kg of tetramethylammonium hydroxide to the reactor at 20℃. Stir at 2000 r / min for 10 min. Then, under nitrogen protection, add 150 kg of tridecafluorooctyltrimethoxysilane monomer to the reactor. Continue stirring for 5 min, and then stir and react at 35℃ for 24 h to allow the polymerized fluorinated polysilsesquioxane to coat the tetraneedle-shaped zinc oxide whiskers. Remove the solvent and unreacted monomer by rotary evaporation. Wash the reaction product twice with anhydrous ethanol and deionized water, respectively, and vacuum dry to obtain the antifungal agent powder.

[0024] Step 2: Add 20 kg of α-lipoic acid, 4 kg of sodium hydroxide and 4000 L of deionized water to the reaction vessel and stir at 200 r / min for 30 min. Then add 9.6 kg of EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and 11.5 kg of NHS (N-hydroxysuccinimide) to the reaction vessel and continue stirring for 5 min to activate the carboxyl group in lipoic acid and obtain the modifier solution.

[0025] Step 3: Add 3.2 kg of chitosan and 160 L of deionized water to the reactor, adjust the pH to 3 with acetic acid solution with a molar concentration of 1 mol / L, stir at 300 r / min for 20 min, then add 40 L of modifier solution and 15 L of anhydrous ethanol as a desiccant to the reactor, stir and react at 20 °C for 16 h to obtain modified chitosan solution.

[0026] Step 4: 100 kg of wood fibers are heat-milled and defibrinated to prepare fiber slurry. 50 L of modified chitosan solution, 13 kg of melamine-modified urea-formaldehyde resin, 33.25 g of ammonium chloride curing agent, and 0.06 kg of mildew inhibitor powder are added to the fiber slurry. The mixture is stirred and mixed for 20 min at 20 °C and 500 r / min. The mixture is dried until the fiber moisture content is 7%. It is then laid into a mold and hot-pressed at 195 °C and 5 MPa for 5 min to obtain a moisture-proof and mildew-resistant medium-density lightweight fiberboard.

[0027] Example 2: This example provides a moisture-proof and mildew-resistant medium-density fiberboard, which is prepared through the following steps:

[0028] Step 1: Add 50 kg of deionized water, 150 kg of tetrahydrofuran, 55 kg of tetraneedle-shaped zinc oxide whiskers, and 0.5 kg of tetramethylammonium hydroxide to the reactor at 22°C. Stir at 2500 r / min for 12 min. Then, under nitrogen protection, add 155 kg of tridecafluorooctyltrimethoxysilane monomer to the reactor. Continue stirring for 8 min, and then stir and react at 35°C for 25 h to allow the polymerized fluorinated polysilsesquioxane to coat the tetraneedle-shaped zinc oxide whiskers. Remove the solvent and unreacted monomer by rotary evaporation. Wash the reaction product twice with anhydrous ethanol and deionized water, respectively, and vacuum dry to obtain the antifungal agent powder.

[0029] Step 2: Add 20 kg of α-lipoic acid, 4 kg of sodium hydroxide and 4000 L of deionized water to the reaction vessel and stir at 250 r / min for 30-40 min. Then add 9.6 kg of EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and 11.5 kg of NHS (N-hydroxysuccinimide) to the reaction vessel and continue stirring for 8 min to activate the carboxyl group in lipoic acid and obtain the modifier solution.

[0030] Step 3: Add 3.2 kg of chitosan and 160 L of deionized water to the reactor, adjust the pH to 3 with acetic acid solution with a molar concentration of 1 mol / L, stir at 400 r / min for 25 min, then add 40 L of modifier solution and 18 L of anhydrous ethanol as a desiccant to the reactor, stir and react at 22 °C for 17 h to obtain modified chitosan solution.

[0031] Step 4: 100 kg of wood fibers are heat-milled and defibrinated to prepare fiber slurry. 55 L of modified chitosan solution, 13.25 kg of melamine-modified urea-formaldehyde resin, 33.5 g of ammonium chloride curing agent, and 0.07 kg of mildew inhibitor powder are added to the fiber slurry. The mixture is stirred and mixed at 22℃ and 600 r / min for 25 min. The mixture is dried until the fiber moisture content is 7.5%. It is then laid into a mold and hot-pressed at 198℃ and 5.5 MPa for 5.5 min to obtain a moisture-proof and mildew-resistant medium-density lightweight fiberboard.

[0032] Example 3: This example provides a moisture-proof and mildew-resistant medium-density fiberboard, which is prepared through the following steps:

[0033] Step 1: Add 50 kg of deionized water, 150 kg of tetrahydrofuran, 60 kg of tetraneedle-shaped zinc oxide whiskers, and 0.5 kg of tetramethylammonium hydroxide to the reactor at 25°C. Stir at 3000 r / min for 15 min. Then, under nitrogen protection, add 160 kg of tridecafluorooctyltrimethoxysilane monomer to the reactor. Continue stirring for 10 min, and then stir and react at 35°C for 26 h to allow the polymerized fluorinated polysilsesquioxane to coat the tetraneedle-shaped zinc oxide whiskers. Remove the solvent and unreacted monomer by rotary evaporation. Wash the reaction product three times with anhydrous ethanol and deionized water, respectively, and vacuum dry to obtain the antifungal agent powder.

[0034] Step 2: Add 20 kg of α-lipoic acid, 4 kg of sodium hydroxide and 4000 L of deionized water to the reaction vessel and stir at 300 r / min for 30-40 min. Then add 9.6 kg of EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and 11.5 kg of NHS (N-hydroxysuccinimide) to the reaction vessel and continue stirring for 10 min to activate the carboxyl group in lipoic acid and obtain the modifier solution.

[0035] Step 3: Add 3.2 kg of chitosan and 160 L of deionized water to the reactor, adjust the pH to 3 with acetic acid solution with a molar concentration of 1 mol / L, stir at 500 r / min for 30 min, then add 40 L of modifier solution and 20 L of anhydrous ethanol as a desiccant to the reactor, stir and react at 25 °C for 18 h to obtain modified chitosan solution.

[0036] Step 4: 100 kg of wood fibers are heat-milled and defibrinated to prepare fiber slurry. 60 L of modified chitosan solution, 13.5 kg of melamine-modified urea-formaldehyde resin, 33.75 g of ammonium chloride curing agent, and 0.08 kg of mildew inhibitor powder are added to the fiber slurry. The mixture is stirred and mixed at 25 °C and 800 r / min for 30 min. The mixture is dried until the fiber moisture content is 8%. It is then laid into a mold and hot-pressed at 200 °C and 6 MPa for 6 min to obtain a moisture-proof and mildew-resistant medium-density lightweight fiberboard.

[0037] Comparative Example 1: Based on Example 3, step four was performed without adding modified chitosan solution and antifungal powder, while the remaining steps remained unchanged to prepare medium-density lightweight fiberboard.

[0038] Comparative Example 2: Based on Example 3, no modified chitosan solution was added in step four, while the remaining steps remained unchanged to prepare a medium-density lightweight fiberboard.

[0039] Comparative Example 3: Based on Example 3, no anti-mold powder was added in step four, while the remaining steps remained unchanged to prepare a medium-density lightweight fiberboard.

[0040] Comparative Example 4: Based on Example 3, in step three, 3.2 kg of chitosan and 160 L of deionized water were added to the reactor, the pH was adjusted to 3 with acetic acid solution with a molar concentration of 1 mol / L, and the mixture was stirred at 500 r / min for 30 min. The resulting chitosan solution was used in step four to replace the modified chitosan solution, and the remaining steps remained unchanged to prepare medium-density lightweight fiberboard.

[0041] Comparative Example 5: Based on Example 3, in step four, the anti-mildew powder was replaced with the same mass of tetra-needle zinc oxide whiskers, while the remaining steps remained unchanged to prepare a medium-density lightweight fiberboard.

[0042] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-5. Different medium-density fiberboard (MDF) samples were cut into 5cm × 5cm × 2cm specimens. The anti-mold rating of different samples was tested according to JIS Z 2801-2000 "Antibacterial Processed Products - Test Methods and Antibacterial Effects". The test bacteria used were *Aspergillus niger* (CFCC 82449) and *Trichoderma viride* (CFCC 85491). The anti-mold rating after 14 days was observed and recorded (0-4 levels; level 0: no mycelium on the sample surface; level 1: surface infection area ≤10%; level 2: surface infection area ≤30%; level 3: surface infection area ≤70%; level 4: surface infection area >70%). Different samples were soaked in water for 24 hours, and the water absorption rate was calculated (water absorption rate = (mass after soaking - mass before soaking) / mass before soaking × 100%). The anti-mold rating of the soaked and dried samples was then tested using the same method. The results are shown in Table 1.

[0043] Table 1

[0044]

[0045] As shown in Table 1, the medium-density lightweight fiberboards in Examples 1-3 have lower water absorption rates and higher mildew resistance levels, and still maintain a high mildew resistance level after soaking for 24 hours. The comparative examples show that the modified chitosan solution and the mildew inhibitor powder synergistically improve the mildew resistance level of the fiberboard. The modified mildew inhibitor powder and the disulfide bond modified chitosan solution can improve the waterproof effect of the fiberboard, with the mildew inhibitor powder having a greater effect on improving the waterproof effect.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A moisture-proof and mildew-resistant medium-density fiberboard, characterized in that, Prepared by the following steps: Wood fibers are thermally ground and defibriled to prepare fiber slurry. Modified chitosan solution, melamine-modified urea-formaldehyde resin, ammonium chloride curing agent and mildew inhibitor powder are added to the fiber slurry. The mixture is stirred and mixed for 20-30 minutes at 20-25℃ and 500-800 r / min. The mixture is dried until the fiber moisture content is 7-8%. The mixture is then laid into a mold and hot-pressed for 5-6 minutes at 195-200℃ and 5-6 MPa to obtain moisture-proof and mildew-resistant medium-density lightweight fiberboard. The antifungal powder is prepared through the following steps: Deionized water, tetrahydrofuran, tetraneedle-shaped zinc oxide whiskers, and tetramethylammonium hydroxide were added to the reactor at 20-25℃. The mixture was stirred at 2000-3000 r / min for 10-15 min. Then, under nitrogen protection, tridecafluorooctyltrimethoxysilane monomer was added to the reactor. After stirring for 5-10 min, the mixture was stirred at 35℃ for 24-26 h to allow the polymerized fluorinated polysilsesquioxane to coat the tetraneedle-shaped zinc oxide whiskers. The solvent and unreacted monomer were removed by rotary evaporation. The reaction product was washed 2-3 times with anhydrous ethanol and deionized water, respectively, and then vacuum dried to obtain the antifungal agent powder. Modified chitosan is prepared through the following steps: Chitosan and deionized water are added to a reaction vessel, and the pH value is adjusted to 3 with acetic acid solution with a molar concentration of 1 mol / L. The mixture is stirred at 300-500 r / min for 20-30 min. Then, a modifier solution and anhydrous ethanol as a desiccant are added to the reaction vessel, and the mixture is stirred and reacted at 20-25℃ for 16-18 h to obtain a modified chitosan solution. The modifier solution is prepared by the following steps: Add α-lipoic acid, sodium hydroxide and deionized water to a reaction vessel and stir at 200-300 r / min for 30-40 min. Then add EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) to the reaction vessel and continue stirring for 5-10 min to activate the carboxyl group in lipoic acid and obtain the modifier solution.

2. The moisture-proof and mildew-resistant medium-density fiberboard according to claim 1, characterized in that, The ratio of wood fiber, modified chitosan solution, melamine-modified urea-formaldehyde resin, ammonium chloride curing agent, and antifungal powder is 100g: 50-60mL: 13-13.5g: 0.03325-0.03375g: 0.06-0.08g.

3. The moisture-proof and mildew-resistant medium-density fiberboard according to claim 1, characterized in that, The mass ratio of deionized water, tetrahydrofuran, tetraneedle-shaped zinc oxide whiskers, tetramethylammonium hydroxide, and tridecafluorooctyltrimethoxysilane monomer is 5:15:5-6:0.05:15-16.

4. The moisture-proof and mildew-resistant medium-density fiberboard according to claim 1, characterized in that, The ratio of chitosan, deionized water, and modifier solution is 3.2g:160mL:40mL:15-20mL.

5. The moisture-proof and mildew-resistant medium-density fiberboard according to claim 1, characterized in that, The ratio of α-lipoic acid, sodium hydroxide, deionized water, EDC and MHS is 0.2g:0.04g:40mL:0.096g:0.115g.

Images