Fiberboard material and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a fiberboard material and a preparation method thereof.The preparation method comprises the following steps that epoxy resin, an epoxy flame retardant and cardanol modified polyphenylene sulfide are added into a mixing machine and stirred for 30-40 min at the temperature of 40-50 DEG C, then esterified straw is added, stirring continues for 20-30 min, a premix is obtained, and the fiberboard material is obtained; adding a phenolic aldehyde amine curing agent into the premix, quickly stirring for 3-5 minutes, paving on a mold, performing hot pressing for 20-30 minutes at the pressure of 8-15 MPa and the temperature of 100-120 DEG C, molding, cooling and demolding to obtain the fiberboard material. The fiberboard material prepared by the invention has good water resistance, stain resistance, oil resistance and flame retardance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a fiberboard material and its preparation method. Background Technology

[0002] Polymer composite boards have wide applications in many fields such as construction and furniture manufacturing. They are characterized by flexible raw material design and controllable performance. Using agricultural and forestry biomass such as straw as fillers to prepare biomass-filled polymer composite boards is an important way to realize the high-value utilization of agricultural and forestry waste and alleviate the shortage of timber resources. Fiberboard, as a common type of composite board, also has the characteristics of uniform material and stable structure, but there are some shortcomings in its use.

[0003] Regarding water resistance, ordinary fiberboard made from straw is highly susceptible to moisture absorption due to the high hydrophilic hydroxyl content of straw, which has poor compatibility with the resin matrix. This leads to the formation of micro-gaps within the board, causing it to swell and deform, affecting not only its appearance but also its strength and lifespan. Prolonged exposure to damp environments damages the internal fiber structure, significantly reducing mechanical properties such as static bending strength and internal bond strength, thus impacting its reliability and stability in practical applications. In terms of stain and oil resistance, traditional fiberboard surfaces are easily stained and oily, making cleaning difficult and affecting both aesthetics and performance. Finally, many fiberboards exhibit poor flame retardancy, making them prone to combustion in emergencies like fires. The combustion process produces large amounts of smoke and toxic gases, posing a serious threat to human safety.

[0004] In summary, existing fiberboard materials have significant shortcomings in terms of water resistance, stain resistance, oil resistance, and flame retardancy, failing to meet the needs of some applications with high performance requirements. Therefore, developing a fiberboard material with excellent water resistance, stain resistance, oil resistance, and flame retardancy is of significant practical importance. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a fiberboard material and a method for preparing the same. The fiberboard material prepared by the present invention has good water resistance, stain resistance, oil resistance and flame retardancy.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a fiberboard material comprising the following weight components: 20-25 parts by weight of epoxy resin, 10-12 parts by weight of esterified straw, 3-5 parts by weight of epoxy flame retardant, 1-2 parts by weight of cashew nut phenol modified polyphenylene sulfide, and 6-8 parts by weight of phenolic amine curing agent. The epoxy-based flame retardant is obtained by reacting triglycidyl isocyanurate with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The cashew phenol-modified polyphenylene sulfide is obtained by reacting cashew phenol with 1,2-epoxy-5-hexene to obtain alkenylated cashew phenol, followed by reaction of the alkenylated cashew phenol with 1,1,3,3-tetramethyldisiloxane, and then reaction with chloromethylated polyphenylene sulfide fibers.

[0007] Further, the preparation method of the esterified straw is as follows: straw, deionized water, sodium hydroxide and chloroacetic acid are added to the reactor in sequence, the pH is controlled to 9-10, and the reaction is carried out at 80-90℃ for 10-12h. After the reaction is completed, the mixture is filtered, washed until neutral, and dried at 50-60℃ for 4-6h to obtain the esterified straw.

[0008] Furthermore, the ratio of straw, deionized water, sodium hydroxide, and chloroacetic acid is 1-1.1g:20-22mL:0.18-0.19g:0.42-0.46g.

[0009] In the above steps, the addition of sodium hydroxide provides a strongly alkaline environment, which activates the hydroxyl groups on the surface of the straw into oxygen anions. Subsequently, the added chloroacetic acid reacts with these activated oxygen anions in a bimolecular nucleophilic substitution reaction, and the chlorine atoms are removed as leaving groups, thereby branching the carbon links containing carboxyl groups to the surface of the straw to obtain esterified straw.

[0010] Further, the preparation method of the epoxy-based flame retardant is as follows: triglycidyl isocyanurate is added to a reactor and stirred and melted at 110-120°C. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and xylene solution are slowly added to the reactor over 1-2 hours. The mixture is heated to 140-150°C and stirred for 6-8 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed, and dried to obtain the epoxy-based flame retardant.

[0011] Furthermore, the ratio of triglycidyl isocyanurate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and xylene is 11.9-12g:8.8-8.9g:50-60mL.

[0012] In the above steps, the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide structure contains an active PH bond, which attacks the epoxy ring of triglycidyl isocyanurate under high temperature conditions, causing the epoxy ring to open and undergo an addition reaction to generate an addition product containing a PC bond and a hydroxyl group. The reaction is carried out in a 1:1 molar ratio, consuming only one of the three epoxy groups of triglycidyl isocyanurate, while the remaining two epoxy groups are retained, thus obtaining an epoxy flame retardant.

[0013] Furthermore, the preparation method of the cashew phenol-modified polyphenylene sulfide is as follows: Step 1: Add cashew nut powder, triethylbenzylammonium chloride, and 4-methoxyphenol to the reactor, stir and heat to 80-90℃, then slowly add 1,2-epoxy-5-hexene dropwise. After the addition is complete, heat to 100-110℃ and react for 6-8 hours. After the reaction is complete, distill under reduced pressure, wash and dry to obtain alkenylated modified cashew nut powder. In the above steps, the phenolic hydroxyl group of cashew phenol attacks the epoxy group of 1,2-epoxy-5-hexene under the catalysis of triethylbenzylammonium chloride, causing it to open the ring. The two are connected by an ether bond, and while retaining the long-chain alkyl group of cashew phenol, a terminal carbon-carbon double bond is introduced to obtain alkenylated modified cashew phenol.

[0014] Step 2: Under nitrogen protection, 1,1,3,3-tetramethyldisiloxane was added to toluene solvent, stirred and heated to 80-90℃, and then caster catalyst was added dropwise. After the addition was complete, alkenylated modified cashew nut powder was added, and the reaction was stirred and kept warm for 60-80 min. After the reaction was completed, the mixture was cooled to room temperature, purified by vacuum distillation, and dried to obtain silane-modified cashew nut powder. In the above steps, under the initiation of the Castel platinum catalyst, the silane-hydrogen bonds at both ends of 1,1,3,3-tetramethyldisiloxane undergo a hydrosilylation reaction with the carbon-carbon double bond at the end of the alkenylated cashew nut shell mol. The siloxane segment with extremely low surface energy is introduced into the cashew nut shell mol molecule through the Si-C bond, resulting in silane-modified cashew nut shell mol.

[0015] Step 3: Add chloromethylated polyphenylene sulfide fiber and silane-modified cashew nut shell powder to N,N-dimethylformamide solvent, stir and mix, then add potassium carbonate and sodium iodide, and react at 90-100℃ for 36-40h. After the reaction is complete, cool to room temperature, precipitate, filter, and wash the filter cake 3-4 times with deionized water. Then put the filter cake into a Soxhlet extractor, use anhydrous ethanol as the extraction solvent, heat to 85-95℃ and extract for 16-20h. Finally, vacuum dry at 60-80℃ for 8-12h to obtain cashew nut shell powder modified polyphenylene sulfide.

[0016] In the above steps, the chloromethyl groups on the chloromethylated polyphenylene sulfide fiber have high reactivity. The potassium carbonate added to the system acts as an acid-binding agent to neutralize the acid generated in the reaction. Sodium iodide converts the chloromethyl groups into iodomethyl groups that are easier to leave through halogen exchange, which greatly accelerates the grafting of silane-modified cashew nut shells onto the polymer backbone of the polyphenylene sulfide fiber through a nucleophilic substitution reaction, thus obtaining cashew nut shell modified polyphenylene sulfide.

[0017] Furthermore, in step one, the ratio of cashew phenol, triethylbenzylammonium chloride, 4-methoxyphenol, and 1,2-epoxy-5-hexene is 10-10.1g:0.1-0.12g:0.01-0.02g:4.8-4.9g.

[0018] Furthermore, in step two, the ratio of toluene, 1,1,3,3-tetramethyldisiloxane, caster catalyst, and alkenylated modified cashew phenol is 15-20 mL: 2.7-2.8 g: 0.05-0.06 mL: 3.2-3.3 g.

[0019] Furthermore, in step three, the ratio of N,N-dimethylformamide, chloromethylated polyphenylene sulfide fiber, silane-modified cashew nut shell powder, potassium carbonate, and sodium iodide is 25-30 mL: 1.5-1.6 g: 1.8-1.9 g: 1.4-1.5 g: 0.12-0.14 g.

[0020] Further, the preparation method of the fiberboard material is as follows: epoxy resin, epoxy flame retardant, and cashew phenol modified polyphenylene sulfide are added to a mixer and stirred at 40-50℃ for 30-40 minutes. Then, esterified straw is added and stirring is continued for 20-30 minutes to obtain a premix. A phenolic amine curing agent is added to the premix and stirred rapidly for 3-5 minutes. Then, the mixture is laid on a mold and hot-pressed at 8-15MPa and 100-120℃ for 20-30 minutes to form the fiberboard material. After cooling, the material is demolded to obtain the fiberboard material.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects: This invention modifies straw through esterification, introducing hydrophobic ester groups to reduce the surface energy of the straw. This reduces the water absorption and swelling of hydroxyl groups while allowing it to form a good interfacial bond with the epoxy resin matrix. Cashew nut shell powder is chemically grafted onto chloromethylated polyphenylene sulfide fibers to prepare cashew nut shell powder-modified polyphenylene sulfide. The grafted hydrophobic long chains form a continuous hydrophobic barrier in the matrix, effectively blocking the penetration path of water molecules. Simultaneously, the chemical cross-linking structure eliminates interfacial gaps between components, preventing water molecules from penetrating along the interface and significantly improving the water resistance of the fiberboard material. Furthermore, the long-chain alkyl and siloxane segments of cashew nut shell powder migrate to the surface during material molding, forming a stable low surface energy layer on the fiberboard surface. This significantly reduces the affinity of the material surface for stains and oil, giving the fiberboard material excellent stain and oil resistance. A phosphorus-nitrogen-containing epoxy flame retardant is prepared by reacting triglycidyl isocyanate with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. This flame retardant participates in the curing and cross-linking of epoxy resin through epoxy groups, becoming part of the network and avoiding the migration problem of small molecule flame retardants. Simultaneously, the polyphenylene sulfide fiber itself contains sulfur, which can form a phosphorus-sulfur synergistic flame retardant system with the epoxy flame retardant. During combustion, this promotes the formation of a dense and continuous char layer, effectively isolating oxygen and heat transfer, thus enhancing the flame retardant performance of the fiberboard material. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The reagents used in the following specific embodiments are of analytical grade. Additionally: Epoxy resin: Grade E51, industrial grade, manufactured by Nantong Xingchen Synthetic Materials Co., Ltd. Phenolic amine curing agent: brand name T-31, industrial grade, manufactured by Guangzhou Carbonhua New Materials Co., Ltd.

[0024] The preparation process of chloromethylated polyphenylene sulfide fibers is referenced from the journal "Polymer Materials Science and Engineering", Volume 29, Issue 11, "Optimization of Chloromethylation Reaction Conditions for Polyphenylene Sulfide Fibers". 2g of polyphenylene sulfide fiber was placed in a hydrothermal reactor, and 20mL of dichloromethane, 50mL of chloromethyl ether and 2mL of anhydrous tin tetrachloride were added. The mixture was tightened and allowed to swell at room temperature for 12h. The hydrothermal reactor was then placed in a 100℃ oil bath for 2h. After the reaction was completed, the fiber was filtered out, soaked in hydrochloric acid, filtered with ethanol for 8h, washed with distilled water, and dried under vacuum to constant weight to obtain chloromethylated polyphenylene sulfide fiber.

[0025] Example 1 (1) Add 1g of straw, 20mL of deionized water, 0.18g of sodium hydroxide and 0.42g of chloroacetic acid to the reactor in sequence, control the pH to 9, react at 80℃ for 10h, filter after the reaction, wash until neutral, and dry at 50℃ for 4h to obtain esterified straw. (2) Add 11.9g of triglycidyl isocyanurate to the reactor and stir to melt at 110°C. Then, slowly add 8.8g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 50mL of xylene solution to the reactor over 1 hour. Heat to 140°C and stir to react for 6 hours. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain epoxy flame retardant. (3) Add 10g of cashew phenol, 0.1g of triethylbenzylammonium chloride and 0.01g of 4-methoxyphenol to the reactor, stir and heat to 80℃, then slowly add 4.8g of 1,2-epoxy-5-hexene. After the addition is complete, heat to 100℃ and react for 6h. After the reaction is complete, distill under reduced pressure, wash and dry to obtain alkenylated modified cashew phenol. (4) Under nitrogen protection, 2.7 g of 1,1,3,3-tetramethyldisiloxane was added to 15 mL of toluene solvent, stirred and heated to 80 °C, and then 0.05 mL of caster catalyst was added dropwise. After the addition was complete, 3.2 g of alkenylated modified cashew nut powder was added, and the mixture was kept warm and stirred for 60 min. After the reaction was completed, the mixture was cooled to room temperature, purified by vacuum distillation, and dried to obtain silane-modified cashew nut powder. (5) Add 1.5g of chloromethylated polyphenylene sulfide fiber and 1.8g of silane-modified cashew nut powder to 25mL of N,N-dimethylformamide solvent, stir and mix, then add 1.4g of potassium carbonate and 0.12g of sodium iodide, react at 90℃ for 36h, after the reaction is completed, cool to room temperature, precipitate, filter, wash the filter cake with deionized water 3 times, then put the filter cake into a Soxhlet extractor, use anhydrous ethanol as the extraction solvent, heat to 85℃ for 16h, and finally vacuum dry at 60℃ for 8h to obtain cashew nut powder modified polyphenylene sulfide; (6) Add 20 parts by weight of epoxy resin, 3 parts by weight of epoxy flame retardant and 1 part by weight of cashew phenol modified polyphenylene sulfide into a mixer and stir at 40°C for 30 min. Then add 10 parts by weight of esterified straw and continue stirring for 20 min to obtain a premix. Add 6 parts by weight of phenolic amine curing agent to the premix and stir quickly for 3 min. Then lay it on a mold and hot press at 8 MPa and 100°C for 20 min to form. Cool and demold to obtain fiberboard material.

[0026] Example 2 (1) Add 1.1g of straw, 22mL of deionized water, 0.19g of sodium hydroxide and 0.46g of chloroacetic acid to the reactor in sequence, control the pH to 10, react at 90℃ for 12h, filter after the reaction, wash until neutral, and dry at 60℃ for 6h to obtain esterified straw. (2) Add 12g of triglycidyl isocyanurate to the reactor and stir to melt at 120°C. Then, slowly add 8.9g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 60mL of xylene solution to the reactor over 2 hours. Heat to 150°C and stir to react for 8 hours. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain epoxy flame retardant. (3) Add 10.1g of cashew phenol, 0.12g of triethylbenzylammonium chloride and 0.02g of 4-methoxyphenol to the reactor, stir and heat to 90℃, then slowly add 4.9g of 1,2-epoxy-5-hexene. After the addition is complete, heat to 110℃ and react for 8h. After the reaction is complete, distill under reduced pressure, wash and dry to obtain alkenylated modified cashew phenol. (4) Under nitrogen protection, 2.8 g of 1,1,3,3-tetramethyldisiloxane was added to 20 mL of toluene solvent, stirred and heated to 90 °C, and then 0.06 mL of caster catalyst was added dropwise. After the addition was complete, 3.3 g of alkenylated modified cashew nut powder was added, and the mixture was kept warm and stirred for 80 min. After the reaction was completed, the mixture was cooled to room temperature, purified by vacuum distillation, and dried to obtain silane-modified cashew nut powder. (5) Add 1.6 g of chloromethylated polyphenylene sulfide fiber and 1.9 g of silane-modified cashew nut powder to 30 mL of N,N-dimethylformamide solvent, stir and mix, then add 1.5 g of potassium carbonate and 0.14 g of sodium iodide, react at 100 °C for 40 h, after the reaction is completed, cool to room temperature, precipitate, filter, wash the filter cake with deionized water 4 times, then put the filter cake into a Soxhlet extractor, use anhydrous ethanol as the extraction solvent, heat to 95 °C for 20 h, and finally vacuum dry at 80 °C for 12 h to obtain cashew nut powder modified polyphenylene sulfide; (6) Add 25 parts by weight of epoxy resin, 5 parts by weight of epoxy flame retardant and 2 parts by weight of cashew phenol modified polyphenylene sulfide into a mixer and stir at 50°C for 40 min. Then add 12 parts by weight of esterified straw and continue stirring for 30 min to obtain a premix. Add 8 parts by weight of phenolic amine curing agent to the premix and stir rapidly for 5 min. Then lay it on a mold and hot press it at 15 MPa and 120°C for 30 min to form. Cool and demold to obtain fiberboard material.

[0027] Example 3 (1) Add 1.05g of straw, 21mL of deionized water, 0.18g of sodium hydroxide and 0.44g of chloroacetic acid to the reactor in sequence, control the pH to 9, react at 85℃ for 11h, filter after the reaction, wash until neutral, and dry at 55℃ for 5h to obtain esterified straw. (2) Add 11.95g of triglycidyl isocyanurate to the reactor and stir to melt at 115°C. Then, slowly add 8.85g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 55mL of xylene solution to the reactor over 1.5h. Heat to 145°C and stir to react for 7h. After the reaction is complete, cool to room temperature, filter, wash and dry to obtain epoxy flame retardant. (3) Add 10.05g of cashew phenol, 0.11g of triethylbenzylammonium chloride and 0.01g of 4-methoxyphenol to the reactor, stir and heat to 85℃, then slowly add 4.85g of 1,2-epoxy-5-hexene. After the addition is complete, heat to 105℃ and react for 7h. After the reaction is complete, distill under reduced pressure, wash and dry to obtain alkenylated modified cashew phenol. (4) Under nitrogen protection, 2.75 g of 1,1,3,3-tetramethyldisiloxane was added to 18 mL of toluene solvent, stirred and heated to 85 °C, and then 0.05 mL of caster catalyst was added dropwise. After the addition was complete, 3.25 g of alkenylated modified cashew nut powder was added, and the mixture was kept warm and stirred for 70 min. After the reaction was completed, the mixture was cooled to room temperature, purified by vacuum distillation, and dried to obtain silane-modified cashew nut powder. (5) Add 1.55g of chloromethylated polyphenylene sulfide fiber and 1.85g of silane-modified cashew nut powder to 28mL of N,N-dimethylformamide solvent, stir and mix, then add 1.45g of potassium carbonate and 0.13g of sodium iodide, react at 95℃ for 38h, after the reaction is completed, cool to room temperature, precipitate, filter, wash the filter cake with deionized water 3 times, then put the filter cake into a Soxhlet extractor, use anhydrous ethanol as the extraction solvent, heat to 90℃ for 18h, and finally vacuum dry at 70℃ for 10h to obtain cashew nut powder modified polyphenylene sulfide; (6) Add 22 parts by weight of epoxy resin, 4 parts by weight of epoxy flame retardant and 1 part by weight of cashew phenol modified polyphenylene sulfide to a mixer and stir at 45°C for 35 min. Then add 11 parts by weight of esterified straw and continue stirring for 25 min to obtain a premix. Add 7 parts by weight of phenolic amine curing agent to the premix and stir rapidly for 4 min. Then lay it on a mold and hot press at 10 MPa and 110°C for 25 min to form. Cool and demold to obtain fiberboard material.

[0028] Comparative Example 1 The main difference between this comparative example and Example 3 is that unmodified straw was used instead of esterified straw.

[0029] Comparative Example 2 The main difference between this comparative example and Example 3 is that 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is used instead of the epoxy flame retardant.

[0030] Comparative Example 3 The main difference between this comparative example and Example 3 is that chloromethylated polyphenylene sulfide fiber is used instead of cashew phenol-modified polyphenylene sulfide.

[0031] Comparative Example 4 The main difference between this comparative example and Example 3 is that, when preparing the fiberboard material, cashew phenol-modified polyphenylene sulfide is not added. Instead, free cashew phenol monomer and chloromethylated polyphenylene sulfide fiber in the same mass ratio as in Example 3 are directly added and incorporated into the system by physical blending. The amounts of other raw materials, preparation of esterified straw, preparation of epoxy flame retardant, and fiberboard forming process are all consistent with those in Example 3.

[0032] Performance testing The fiberboard materials obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests.

[0033] (1) Mechanical property testing: The static bending strength, internal bond strength and external bond strength of the fiberboard materials prepared in Examples 1-3 and Comparative Examples 1-4 were tested according to GB / T17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". Ten specimens were tested for each test, and the average value of the test results was taken. The test results are shown in Table 1.

[0034] Table 1: Mechanical Performance Tests project Static bending strength (MPa) Internal bond strength (MPa) External bond strength (MPa) Example 1 48.8 2.28 2.21 Example 2 52.5 2.35 2.28 Example 3 50.6 2.32 2.24 Comparative Example 1 35.6 1.82 1.75 Comparative Example 2 45.3 2.15 2.08 Comparative Example 3 41.2 1.95 1.88 Comparative Example 4 38.5 1.78 1.71 As can be seen from Table 1, the fiberboard materials prepared in Examples 1-3 have good mechanical properties.

[0035] (2) Water resistance test: Referring to GB / T17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", the fiberboard materials prepared in Examples 1-3 and Comparative Examples 1-4 were tested for 24-hour water absorption rate and 24-hour water absorption thickness expansion rate. The fiberboard materials were prepared into sizes of 5cm×5cm×0.4cm, and three parallel tests were performed for each group. The average value of the test results was taken. The test results are shown in Table 2.

[0036] Table 2: Water Resistance Test project Water absorption rate (%) Water absorption thickness swelling rate (%) Example 1 4.1 2.7 Example 2 3.6 2.2 Example 3 3.8 2.5 Comparative Example 1 12.2 8.8 Comparative Example 2 6.5 4.5 Comparative Example 3 7.5 5.1 Comparative Example 4 8.2 5.6 As can be seen from Table 2, the fiberboard materials prepared in Examples 1-3 have good water resistance.

[0037] (3) Stain resistance, oil resistance, and flame retardancy tests: Stain resistance was tested according to GB / T34722-2025 "Impregnated Paper-faced Plywood and Blockboard"; vegetable oil contact angle was tested using a contact angle meter according to the principle specified in GB / T30693-2014 "Measurement of Contact Angle between Plastic Film and Water"; flame retardancy was tested according to GB / T2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method - Part 2: Room Temperature Test". The test results are shown in Table 3.

[0038] Table 3: Stain resistance, oil resistance, and flame retardant performance tests project Pollution resistance rating (level) Contact angle of vegetable oil (°) Limiting oxygen index (%) Example 1 5 71 31.5 Example 2 5 75 33.6 Example 3 5 73 32.2 Comparative Example 1 3 45 30.5 Comparative Example 2 4 63 28.5 Comparative Example 3 3 55 31.0 Comparative Example 4 4 48 30.8 As can be seen from Table 3, the fiberboard materials prepared in Examples 1-3 have good stain resistance, oil resistance, and flame retardant properties.

[0039] The comparison shows that Comparative Example 1 uses unmodified straw instead of esterified straw. The surface of unmodified straw contains a large number of free hydroxyl groups, exhibiting strong hydrophilicity and polarity. This results in extremely poor compatibility with the non-polar epoxy resin matrix, making it unable to form an effective interfacial bond. Therefore, it is very easy to break at the interface under stress. At the same time, a large number of exposed hydrophilic groups will swell when exposed to water, causing damage to the internal structure of the board. Stains and oil stains can easily penetrate, and during combustion, the interfacial defects lead to a non-dense char layer, resulting in a decrease in performance. Comparative Example 2 uses 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide instead of epoxy flame retardant. Ordinary 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide monomers are small molecules and cannot participate in the curing and cross-linking network of epoxy resin through epoxy groups like epoxy flame retardants. Free small molecules are prone to agglomeration or migration in the system, resulting in a decrease in the cross-linking density of the board, thus causing a decrease in performance. Comparative Example 3 uses... Replacing cashew phenol-modified polyphenylene sulfide (PPS) with chloromethylated PPS fibers, the unmodified PPS fibers exhibit chemical inertness, resulting in poor dispersibility and weak interfacial bonding in the epoxy resin matrix. This leads to stress defects and a decrease in mechanical strength. Furthermore, the lack of the low surface energy structure provided by cashew phenol modification prevents the formation of an effective hydrophobic and oleophobic barrier on the material surface, allowing vegetable oils to easily penetrate and significantly reducing the contact angle, thus degrading performance. In Comparative Example 4, free cashew phenol monomers and chloromethylated PPS fibers were directly added and incorporated into the system through physical blending. During direct physical blending, the free cashew phenol monomers not only failed to adhere to the chloromethylated PPS fibers to improve dispersibility but also remained free in the epoxy resin network, severely disrupting the crosslinking density of the epoxy resin and further deteriorating mechanical strength. Simultaneously, the free hydrophobic monomers could not form a stable low surface energy network on the material surface and were easily lost or aggregated, leading to a decrease in the contact angle of vegetable oils and a decline in performance.

[0040] It should be noted that, in this document, 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 a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0042] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A fiberboard material, characterized in that, It includes the following components by weight: 20-25 parts epoxy resin, 10-12 parts esterified straw, 3-5 parts epoxy flame retardant, 1-2 parts cashew phenol modified polyphenylene sulfide, and 6-8 parts phenolic amine curing agent. The epoxy-based flame retardant is obtained by reacting triglycidyl isocyanurate with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The cashew phenol-modified polyphenylene sulfide is obtained by reacting cashew phenol with 1,2-epoxy-5-hexene to obtain alkenylated cashew phenol, followed by reaction of the alkenylated cashew phenol with 1,1,3,3-tetramethyldisiloxane, and then reaction with chloromethylated polyphenylene sulfide fibers.

2. The fiberboard material according to claim 1, characterized in that, The preparation method of the esterified straw is as follows: straw, deionized water, sodium hydroxide and chloroacetic acid are added to the reactor in sequence, the pH is controlled to 9-10, and the reaction is carried out at 80-90℃ for 10-12h. After the reaction is completed, the straw is filtered, washed until neutral, and dried at 50-60℃ for 4-6h to obtain esterified straw.

3. The fiberboard material according to claim 2, characterized in that, The ratio of straw, deionized water, sodium hydroxide, and chloroacetic acid used is 1-1.1g: 20-22mL: 0.18-0.19g: 0.42-0.46g.

4. The fiberboard material according to claim 1, characterized in that, The preparation method of the epoxy-based flame retardant is as follows: Triglycidyl isocyanurate is added to a reactor and stirred and melted at 110-120℃. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and xylene solution are slowly added to the reactor over 1-2 hours. The mixture is heated to 140-150℃ and stirred for 6-8 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain the epoxy-based flame retardant.

5. The fiberboard material according to claim 4, characterized in that, The ratio of triglycidyl isocyanurate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and xylene is 11.9-12 g: 8.8-8.9 g: 50-60 mL.

6. The fiberboard material according to claim 1, characterized in that, The preparation method of the cashew phenol modified polyphenylene sulfide is as follows: Step 1: Add cashew nut powder, triethylbenzylammonium chloride, and 4-methoxyphenol to the reactor, stir and heat to 80-90℃, then slowly add 1,2-epoxy-5-hexene dropwise. After the addition is complete, heat to 100-110℃ and react for 6-8 hours. After the reaction is complete, distill under reduced pressure, wash and dry to obtain alkenylated modified cashew nut powder. Step 2: Under nitrogen protection, 1,1,3,3-tetramethyldisiloxane was added to toluene solvent, stirred and heated to 80-90℃, and then caster catalyst was added dropwise. After the addition was complete, alkenylated modified cashew nut powder was added, and the reaction was stirred and kept warm for 60-80 min. After the reaction was completed, the mixture was cooled to room temperature, purified by vacuum distillation, and dried to obtain silane-modified cashew nut powder. Step 3: Add chloromethylated polyphenylene sulfide fiber and silane-modified cashew nut shell powder to N,N-dimethylformamide solvent, stir and mix, then add potassium carbonate and sodium iodide, and react at 90-100℃ for 36-40h. After the reaction is complete, cool to room temperature, precipitate, filter, and wash the filter cake 3-4 times with deionized water. Then put the filter cake into a Soxhlet extractor, use anhydrous ethanol as the extraction solvent, heat to 85-95℃ and extract for 16-20h. Finally, vacuum dry at 60-80℃ for 8-12h to obtain cashew nut shell powder modified polyphenylene sulfide.

7. The fiberboard material according to claim 6, characterized in that, In step one, the ratio of cashew phenol, triethylbenzylammonium chloride, 4-methoxyphenol, and 1,2-epoxy-5-hexene is 10-10.1g:0.1-0.12g:0.01-0.02g:4.8-4.9g.

8. The fiberboard material according to claim 6, characterized in that, In step two, the ratio of toluene, 1,1,3,3-tetramethyldisiloxane, caster catalyst, and alkenylated modified cashew phenol is 15-20 mL: 2.7-2.8 g: 0.05-0.06 mL: 3.2-3.3 g.

9. The fiberboard material according to claim 6, characterized in that, In step three, the ratio of N,N-dimethylformamide, chloromethylated polyphenylene sulfide fiber, silane-modified cashew nut shell phenol, potassium carbonate, and sodium iodide is 25-30 mL: 1.5-1.6 g: 1.8-1.9 g: 1.4-1.5 g: 0.12-0.14 g.

10. A method for preparing a fiberboard material as described in any one of claims 1-9, characterized in that, The fiberboard material is prepared as follows: epoxy resin, epoxy flame retardant, and cashew phenol modified polyphenylene sulfide are added to a mixer and stirred at 40-50℃ for 30-40 minutes. Then, esterified straw is added and stirring is continued for 20-30 minutes to obtain a premix. A phenolic amine curing agent is added to the premix and stirred rapidly for 3-5 minutes. The mixture is then laid on a mold and hot-pressed at 8-15MPa and 100-120℃ for 20-30 minutes to form the fiberboard material. After cooling, the material is demolded to obtain the fiberboard material.