Preparation process of high-performance green flame-retardant plywood

Abstract

The invention relates to a preparation process of high-performance green flame-retardant plywood, which comprises the following steps: synthesis of a cross-linking agent furandicarboxylic acid-NHS active ester (FDCA-NHS), preparation of a high-temperature meal adhesive, preparation of waterborne epoxy resin, preparation of an L-Trp-DOPO inorganic phosphorus-containing flame retardant, preparation of an epoxy resin flame-retardant material, preparation of the high-performance green flame-retardant plywood and the like. The preparation method creatively combines the esterification reaction, the phase inversion method, the chemical one-step method, the hot pressing method and other preparation methods, the prepared high-performance green flame-retardant plywood has the advantages of being good in mechanical property, excellent in flame retardance and the like, has the characteristics of being wide in raw material source, high in renewability, high in reaction activity and the like, conforms to the green and environment-friendly concept and has wide application prospects. The plywood is wide in application field and wide in application prospect.

Description

Technical Field

[0001] The invention relates to a new material preparation, in particular to a preparation process of a high-performance green flame-retardant plywood. Background Art

[0002] With the rapid development of the wood-based panel industry, the environmental performance of adhesives has received widespread attention from consumers. Synthetic resin adhesives made from petrochemical products have excellent bonding properties and water resistance, but some synthetic resins contain formaldehyde, phenol and other substances, which can cause harm to the environment and human health during production, transportation and use. The development of safe, environmentally friendly and environmentally friendly adhesives has become the focus of today's adhesive research and future development trend. Therefore, environmentally friendly and renewable plant protein adhesives have been valued and favored by the industry. In addition, wood is flammable, and there are fire hazards in the use of wood-based panels in building decoration. With the implementation of relevant laws and regulations and standard systems for flame retardant materials in my country, higher requirements have been put forward for flame retardant materials, and the flame retardant performance of wood-based panels has become one of the main factors for consumers to choose.

[0003] The present invention utilizes soybean protein to prepare green flame retardant plywood, and adopts high temperature meal to replace low temperature meal to prepare soybean meal adhesive. The thermochemical modification of high temperature meal can significantly improve the shortcomings of adhesive bonding strength and water resistance, and has the following characteristics: (1) strong regeneration ability, (2) high reaction activity, etc., which conforms to the green concept, and effectively improves the resistance of soybean meal to normal aging and the storage stability of soybean meal, while effectively reducing the raw material cost of adhesive. The green flame retardant plywood manufactured by combining with the new composite flame retardant also has good flame retardancy, which is of positive significance for the expansion of the application field of green flame retardant plywood and the promotion and application of soybean meal adhesive in the wood industry. Summary of the invention

[0004] In view of the above problems, the present invention provides a preparation process of high-performance green flame-retardant plywood.

[0005] The invention provides a preparation process of a high-performance green flame retardant plywood, comprising the following steps: synthesis of a cross-linking agent furandicarboxylic acid-NHS active ester (FDCA-NHS), preparation of a high-temperature meal adhesive, preparation of a water-based epoxy resin, preparation of an L-Trp-DOPO inorganic phosphorus-containing flame retardant, preparation of an epoxy resin flame retardant material, and preparation of a high-performance green flame retardant plywood.

[0006] Wherein, step (4) preparation of L-Trp-DOPO inorganic phosphorus-containing flame retardant A certain amount of L-Trp-BS and an organic phosphorus compound (DOPO) were weighed and dissolved in a three-necked flask filled with tetrahydrofuran, and the mixture was fully stirred. The mixed solution was placed in an oil bath and reacted for a period of time. The precipitated dark yellow product was washed with ethanol and deionized water, and dried overnight in a forced air oven at a certain temperature to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material The flame retardant L-Trp-DOPO prepared in step (4) is dissolved in anhydrous ethanol, fully dispersed in a water bath for a period of time, the epoxy resin obtained in step (3) is added and stirred, and then diethylenetriamine is added to the above mixed solution. The anhydrous ethanol is removed by vacuum filter. After a period of time, the mixed solution is poured into a preheated template, degassed in an oven, and the sample is placed in an oven for curing for a period of time, and then the oven is switched to a programmed temperature rise for storage.

[0007] Preferably, step (1) the synthesis of the crosslinking agent furan dicarboxylic acid-NHS active ester (FDCA-NHS) 2,5-furandicarboxylic acid (FDCA) and N-hydroxysuccinimide (NHS) are dissolved in dimethyl sulfoxide (DMSO), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) is added to the above solution, the mixed reaction liquid is stirred at a certain temperature, after the reaction is completed, dimethyl sulfoxide (DMSO) is washed away by an extraction method, the reaction product is purified by column chromatography, and finally dried in a vacuum drying oven at a certain temperature for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder for grinding and sieving to obtain high-temperature soybean meal powder. Add water to the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution obtained in step (1), stir evenly at room temperature, adjust the solid content of the solvent, then add the soybean meal powder, stir at room temperature to form a uniform soybean meal adhesive without particles, and obtain a high-temperature meal adhesive. Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a three-necked flask equipped with a stirrer and a condenser, heat and heat up, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly and heat up to obtain a non-ionic epoxy emulsifier, lower the temperature, add epoxy resin E-54, stir to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a certain stirring speed. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for a period of time to obtain a water-based epoxy resin; Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant A certain amount of L-Trp-BS and an organic phosphorus compound (DOPO) were weighed and dissolved in a three-necked flask filled with tetrahydrofuran, and the mixture was fully stirred. The mixed solution was placed in an oil bath and reacted for a period of time. The precipitated dark yellow product was washed with ethanol and deionized water, and dried overnight in a forced air oven at a certain temperature to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material The flame retardant L-Trp-DOPO prepared in step (4) is dissolved in anhydrous ethanol, fully dispersed in a water bath for a period of time, the epoxy resin obtained in step (3) is added and stirred, and then diethylenetriamine is added to the mixed solution, and the anhydrous ethanol is removed by vacuum filter. After a period of time, the mixed solution is poured into a preheated template, and the bubbles are removed in an oven. The sample is placed in an oven for curing for a period of time, and then the oven is switched to a programmed temperature rise for storage; Step (6) Preparation of high-performance green flame-retardant plywood Use five-layer eucalyptus veneer, use the high-temperature cake adhesive obtained in step (2), add the epoxy resin flame retardant material obtained in step (5), and set an appropriate single-sided glue coating amount; use a pre-pressing process: set a unit pressure, cold press for a period of time; hot pressing process: set the hot pressing temperature and unit pressure, hot press for a period of time, exhaust the unit pressure for a certain period of time, and after the exhaust time is completed, obtain a high-performance green flame retardant plywood.

[0008] Preferably, step (1) the synthesis of the crosslinking agent furan dicarboxylic acid-NHS active ester (FDCA-NHS) 2.8-3.1 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6-7.1 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15-23 mL of dimethyl sulfoxide (DMSO), and 5.6-6.9 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction liquid was stirred at 25-35°C for 48-56 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography. Finally, it was dried in a vacuum drying oven at 50-60°C for use.

[0009] The present invention has the advantages that the cross-linking agent furandicarboxylic acid-NHS active ester is synthesized by esterification reaction, wherein 2,5-furandicarboxylic acid (FDCA) as an important component of FDCA-NHS has excellent biodegradability, so that the furandicarboxylic acid-NHS active ester (FDCA-NHS) can be naturally decomposed under specific conditions, reducing pollution to the environment, conforming to the current trend of green chemistry and sustainable development, and the N-hydroxysuccinimide (NHS) active ester part gives the furandicarboxylic acid-NHS active ester (FDCA-NHS) good reaction activity and selectivity, providing an excellent basis for subsequent modification steps.

[0010] Preferably, step (2) preparation of high temperature meal adhesive Put the flake soybean meal into a grinder for pulverization for 5-8 minutes, and pass it through a 160-200 mesh sieve to obtain high-temperature soybean meal powder. Take 89.55-91.65 g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4-15.6 wt%) obtained in step (1), add 10.45-11.95 g of water thereto, stir evenly at room temperature, adjust the solid content of the solvent to 12.0-13.0 wt%, then add 30.00-35.00 g of soybean meal powder, stir at room temperature for 3-5 minutes, and form a soybean meal adhesive with a solid content of 30-35 wt% and no particles, thereby obtaining a high-temperature meal adhesive.

[0011] The present invention has the advantages that the present invention uses biomass as a raw material to prepare an adhesive, which has a low source cost and conforms to the green concept. In addition, compared with low-temperature meal, the high-temperature meal is appropriately modified, so that the bonding strength and water resistance of the high-temperature meal adhesive are improved and better than the low-temperature meal adhesive, making it more suitable for use in the preparation of soybean meal adhesive, thereby promoting the value-added utilization of high-temperature meal and effectively saving the cost of glue making.

[0012] Preferably, step (3) preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250-300 mL three-necked flask equipped with a stirrer and a condenser, heat to 80-90°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip it into the flask, mix evenly for 30-35 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70-75°C, add epoxy resin E-54, stir for 30-35 minutes to mix it and the epoxy emulsifier evenly, and then slowly drip distilled water at a stirring speed of 1000-1200 r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30-35 minutes to obtain a water-based epoxy resin with a solid content of 50-52%.

[0013] Preferably, step (4) preparation of L-Trp-DOPO inorganic phosphorus-containing flame retardant Weigh 1.42-1.86 g L-Trp-BS and 0.75-1 g organophosphorus compound (DOPO) and dissolve them in a three-necked flask containing 45-55 mL tetrahydrofuran, and stir them thoroughly. Put the mixed solution into an oil bath at 110-120 °C and react for 12-14 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a forced air oven at 60-65 °C overnight to obtain L-Trp-DOPO inorganic phosphorus-containing flame retardant.

[0014] The invention has the advantages that an environmentally friendly, low-toxic and highly efficient L-Trp-DOPO flame retardant is synthesized by using L-tryptophan, 1,4-phthalaldehyde and an organic phosphorus compound (DOPO) as raw materials, and a novel phosphorus-containing flame retardant L-Trp-DOPO is synthesized by using a Schiff base reaction and then introducing the organic phosphorus compound (DOPO) into the Schiff base structure. The novel flame retardant has more excellent flame retardancy.

[0015] Preferably, step (5) preparation of epoxy resin flame retardant material The flame retardant L-Trp-DOPO prepared in step (4) is dissolved in 15-20 mL of anhydrous ethanol and fully dispersed in a 70-75°C water bath for 15-20 min. 30-35 mL of the epoxy resin obtained in step (3) is added and stirred for 30-45 min. Then, 3.4-4.2 mL of diethylenetriamine is added to the mixed solution. The anhydrous ethanol is removed by vacuum filter for 5-7 min. The mixed solution is poured into a preheated template and degassed in an oven at 80-90°C. The sample is placed in an oven at 80-90°C for curing for 30-35 min. The oven is then switched to a programmed temperature rise to 110-115°C and maintained for 3-4 h.

[0016] The advantage of adopting the present invention is that the present invention cross-links the new flame retardant with the epoxy resin. While the cross-linked material has excellent flame retardancy, the original mechanical properties of the epoxy resin are not destroyed. This shows that the flame retardant L-Trp-DOPO is uniformly dispersed in the epoxy resin matrix, and the non-combustible gas (such as NO, NO2, etc.) generated when the epoxy resin flame retardant material burns can be used as a diluent for the combustible gas, thereby effectively playing a gas phase flame retardant role.

[0017] Preferably, step (6) preparation of high performance green flame retardant plywood A five-layer eucalyptus veneer is used, the high-temperature cake adhesive obtained in step (2) is used, and the epoxy resin flame retardant material obtained in step (5) is added at the same time, and the single-side glue coating amount is (260±10) g / m2; a pre-pressing process is used: the unit pressure is (0.7±0.1) MPa, and the cold pressing time is 1~1.5 hours; a hot pressing process is used: the hot pressing temperature is 125~150°C, the unit pressure is (0.7±0.1) MPa, the hot pressing time is 780~800 seconds, the exhaust unit pressure is (0.2±0.1) MPa, and the exhaust time is 120~130 seconds, to obtain a high-performance green flame retardant plywood.

[0018] The invention has the advantages that biomass raw materials are used to prepare green and environmentally friendly adhesives, and are used together with new composite flame retardant materials to prepare green flame retardant plywood. High-temperature meal is used to prepare soybean meal adhesive, and thermochemical modification improves the bonding strength and water resistance of the high-temperature meal adhesive and makes it better than the low-temperature meal adhesive. In addition, biomass raw materials have the characteristics of strong regeneration ability and high reaction activity, which conforms to the green concept. The addition of new flame retardant materials makes the plywood have excellent flame retardancy and mechanical properties at the same time.

[0019] In summary, the present invention has the following beneficial effects: 1. The present invention has the advantages that the present invention utilizes esterification reaction to synthesize the cross-linking agent furandicarboxylic acid-NHS active ester, wherein 2,5-furandicarboxylic acid (FDCA) as an important component of FDCA-NHS has excellent biodegradability, so that furandicarboxylic acid-NHS active ester (FDCA-NHS) can be naturally decomposed under specific conditions, reducing pollution to the environment, which is in line with the current trend of green chemistry and sustainable development, and the N-hydroxysuccinimide (NHS) active ester part gives furandicarboxylic acid-NHS active ester (FDCA-NHS) good reactivity and selectivity, providing an excellent basis for subsequent modification steps; 2. The present invention has the advantages that the present invention uses biomass as raw material to make adhesive, which has low source cost and conforms to the green concept, and compared with low-temperature meal, the high-temperature meal is appropriately modified, so that the bonding strength and water resistance of the high-temperature meal adhesive are improved and better than the low-temperature meal adhesive, making it more suitable for the preparation of soybean meal adhesive, thereby promoting the value-added utilization of high-temperature meal and effectively saving the cost of glue making; 3. The present invention has the advantages of using L-tryptophan, 1,4-phthalaldehyde and an organic phosphorus compound (DOPO) as raw materials to synthesize an environmentally friendly, low-toxic and highly efficient L-Trp-DOPO flame retardant, and using the Schiff base reaction to introduce the organic phosphorus compound (DOPO) into the Schiff base structure to synthesize a new type of phosphorus-containing flame retardant L-Trp-DOPO, which has more excellent flame retardancy; 4. The present invention has the advantage that the present invention cross-links the novel flame retardant with the epoxy resin, and the cross-linked material has excellent flame retardancy while the original mechanical properties of the epoxy resin are not destroyed. This indicates that the flame retardant L-Trp-DOPO is uniformly dispersed in the epoxy resin matrix, and the non-combustible gas (such as NO, NO2, etc.) generated when the epoxy resin flame retardant material burns can be used as a diluent for the combustible gas, thereby effectively playing a gas phase flame retardant role; 5. The advantages of the present invention are that the present invention uses biomass raw materials to prepare green and environmentally friendly adhesives, and uses new composite flame retardant materials to prepare green flame retardant plywood. High-temperature meal is used to prepare soybean meal adhesive. The thermochemical modification improves the bonding strength and water resistance of the high-temperature meal adhesive and is superior to the low-temperature meal adhesive. In addition, biomass raw materials have the characteristics of strong regeneration ability and high reaction activity, which conforms to the green concept. The addition of new flame retardant materials makes the plywood have excellent flame retardancy and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A process flow chart for preparing high-performance green flame-retardant plywood. DETAILED DESCRIPTION

[0021] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and substance of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention.

[0022] If not otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art. In addition, all the raw materials used in the examples are known commercial products. Example 1

[0023] Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2.8 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15 mL of dimethyl sulfoxide (DMSO), and 5.6 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction solution was stirred at 25°C for 48 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography, and finally dried in a vacuum drying oven at 50°C for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder and grind it for 5 minutes, and pass it through a 100-mesh sieve to obtain high-temperature soybean meal powder. Take 89.55g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4wt%) prepared in step (1), add 10.45g of water, stir at room temperature to adjust the solid content of the solvent to 12.0wt%, then add 30.00g of soybean meal powder, stir at room temperature for 3 minutes to form a soybean meal adhesive with a solid content of 30wt% and uniformity without particles, and obtain a high-temperature meal adhesive; Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250mL three-necked flask equipped with a stirrer and a condenser, heat to 80°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly for 30 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70°C, add epoxy resin E-54, stir for 30 minutes to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a stirring speed of 1000r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30 minutes to obtain a water-based epoxy resin with a solid content of 50%; Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42 g of L-Trp-BS and 0.75 g of an organic phosphorus compound (DOPO) and dissolve them in a three-necked flask filled with 45 mL of tetrahydrofuran, and stir them thoroughly. Put the mixed solution into a 110°C oil bath and react for 12 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a 60°C forced air oven overnight to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material Dissolve 1 g of the synthetic flame retardant L-Trp-DOPO prepared in step (4) in 15 mL of anhydrous ethanol, fully disperse in a 70°C water bath for 15 min, add 30 mL of the epoxy resin obtained in step (3) and stir for 30 min, then add 3.4 mL of diethylenetriamine to the mixed solution, remove the anhydrous ethanol with a vacuum filter for 5 min, pour the mixed solution into a preheated template, remove bubbles in an 80°C oven, place the sample in an 80°C oven for curing for 30 min, then switch the oven to a programmed temperature increase to 110°C and maintain for 3 h; Step (6) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (2), and add the epoxy resin flame retardant material obtained in step (5), with a single-sided adhesive coating of 265g / m 2; Use pre-pressing process: unit pressure 0.7MPa, cold pressing time 1h; hot pressing process: hot pressing temperature 125℃, unit pressure 0.7MPa, hot pressing time 780s, exhaust unit pressure 0.2MPa, exhaust time 120s to obtain high-performance green flame-retardant plywood. Example 2

[0024] Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2.8 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15 mL of dimethyl sulfoxide (DMSO), and 5.6 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction solution was stirred at 25°C for 48 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography, and finally dried in a vacuum drying oven at 50°C for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder and grind it for 5 minutes, and pass it through a 120-mesh sieve to obtain high-temperature soybean meal powder. Take 89.55g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4wt%) prepared in step (1), add 10.45g of water, stir at room temperature to adjust the solid content of the solvent to 12.0wt%, then add 30.00g of soybean meal powder, stir at room temperature for 3 minutes to form a soybean meal adhesive with a solid content of 30wt% and uniformity without particles, and obtain a high-temperature meal adhesive; Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250mL three-necked flask equipped with a stirrer and a condenser, heat to 80°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly for 30 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70°C, add epoxy resin E-54, stir for 30 minutes to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a stirring speed of 1000r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30 minutes to obtain a water-based epoxy resin with a solid content of 50%; Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42 g of L-Trp-BS and 0.75 g of an organic phosphorus compound (DOPO) and dissolve them in a three-necked flask filled with 45 mL of tetrahydrofuran, and stir them thoroughly. Put the mixed solution into a 110°C oil bath and react for 12 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a 60°C forced air oven overnight to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material 1.2 g of the synthetic flame retardant L-Trp-DOPO prepared in step (4) was dissolved in 15 mL of anhydrous ethanol, and the mixture was fully dispersed in a 70°C water bath for 15 min. 30 mL of the epoxy resin prepared in step (3) was added and stirred for 30 min. 3.4 mL of diethylenetriamine was then added to the mixed solution. The anhydrous ethanol was removed by vacuum filtration for 5 min. The mixed solution was poured into a preheated template and degassed in an 80°C oven. The sample was placed in an 80°C oven for curing for 30 min, and then the oven was switched to a programmed temperature rise to 110°C and maintained for 3 h. Step (6) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (2), and add the epoxy resin flame retardant material obtained in step (5), with a single-sided adhesive coating of 265g / m 2 ; Use pre-pressing process: unit pressure 0.7MPa, cold pressing time 1h; hot pressing process: hot pressing temperature 125℃, unit pressure 0.7MPa, hot pressing time 780s, exhaust unit pressure 0.2MPa, exhaust time 120s to obtain high-performance green flame-retardant plywood. Example 3

[0025] Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2.8 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15 mL of dimethyl sulfoxide (DMSO), and 5.6 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction solution was stirred at 25°C for 48 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography, and finally dried in a vacuum drying oven at 50°C for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder and grind it for 5 minutes, and pass it through a 160-mesh sieve to obtain high-temperature soybean meal powder. Take 89.55g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4wt%) prepared in step (1), add 10.45g of water, stir at room temperature to adjust the solid content of the solvent to 12.0wt%, then add 30.00g of soybean meal powder, stir at room temperature for 3 minutes to form a soybean meal adhesive with a solid content of 30wt% and uniformity without particles, and obtain a high-temperature meal adhesive; Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250mL three-necked flask equipped with a stirrer and a condenser, heat to 80°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly for 30 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70°C, add epoxy resin E-54, stir for 30 minutes to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a stirring speed of 1000r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30 minutes to obtain a water-based epoxy resin with a solid content of 50%; Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42 g of L-Trp-BS and 0.75 g of an organic phosphorus compound (DOPO) and dissolve them in a three-necked flask filled with 45 mL of tetrahydrofuran, and stir them thoroughly. Put the mixed solution into a 110°C oil bath and react for 12 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a 60°C forced air oven overnight to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material Dissolve 2.6 g of the synthetic flame retardant L-Trp-DOPO prepared in step (4) in 15 mL of anhydrous ethanol, fully disperse in a 70°C water bath for 15 min, add 30 mL of the epoxy resin prepared in step (3) and stir for 30 min, then add 3.4 mL of diethylenetriamine to the above mixed solution, remove the anhydrous ethanol with a vacuum filter for 5 min, pour the mixed solution into a preheated template, remove bubbles in an 80°C oven, place the sample in an 80°C oven for curing for 30 min, then switch the oven to a programmed temperature increase to 110°C and maintain for 3 h; Step (6) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (2), and add the epoxy resin flame retardant material obtained in step (5), with a single-sided adhesive coating of 265g / m 2; Use pre-pressing process: unit pressure 0.7MPa, cold pressing time 1h; hot pressing process: hot pressing temperature 125℃, unit pressure 0.7MPa, hot pressing time 780s, exhaust unit pressure 0.2MPa, exhaust time 120s to obtain high-performance green flame-retardant plywood. Example 4

[0026] Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2.8 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15 mL of dimethyl sulfoxide (DMSO), and 5.6 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction solution was stirred at 25°C for 48 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography, and finally dried in a vacuum drying oven at 50°C for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder and grind it for 5 minutes, and pass it through a 200-mesh sieve to obtain high-temperature soybean meal powder. Take 89.55g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4wt%) prepared in step (1), add 10.45g of water, stir at room temperature to adjust the solid content of the solvent to 12.0wt%, then add 30.00g of soybean meal powder, stir at room temperature for 3 minutes to form a soybean meal adhesive with a solid content of 30wt% and uniformity without particles, and obtain a high-temperature meal adhesive; Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250mL three-necked flask equipped with a stirrer and a condenser, heat to 80°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly for 30 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70°C, add epoxy resin E-54, stir for 30 minutes to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a stirring speed of 1000r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30 minutes to obtain a water-based epoxy resin with a solid content of 50%; Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42 g of L-Trp-BS and 0.75 g of an organic phosphorus compound (DOPO) and dissolve them in a three-necked flask filled with 45 mL of tetrahydrofuran, and stir them thoroughly. Put the mixed solution into a 110°C oil bath and react for 12 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a 60°C forced air oven overnight to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material 1.7 g of the synthetic flame retardant L-Trp-DOPO prepared in step (4) was dissolved in 15 mL of anhydrous ethanol, and the mixture was fully dispersed in a 70°C water bath for 15 min. 30 mL of the epoxy resin prepared in step (3) was added and stirred for 30 min. 3.4 mL of diethylenetriamine was then added to the mixed solution. The anhydrous ethanol was removed by vacuum filtration for 5 min. The mixed solution was poured into a preheated template and degassed in an 80°C oven. The sample was placed in an 80°C oven for curing for 30 min, and then the oven was switched to a programmed temperature rise to 110°C and maintained for 3 h. Step (6) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (2), and add the epoxy resin flame retardant material obtained in step (5), with a single-sided adhesive coating of 265g / m 2 ; Use pre-pressing process: unit pressure 0.7MPa, cold pressing time 1h; hot pressing process: hot pressing temperature 125℃, unit pressure 0.7MPa, hot pressing time 780s, exhaust unit pressure 0.2MPa, exhaust time 120s to obtain high-performance green flame-retardant plywood.

[0027] Comparative Example 1

[0028] Step (1) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder for 5 minutes, and pass it through a 220-mesh sieve to obtain high-temperature soybean meal powder, take 89.55g of a cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4wt%), add 10.45g of water, stir evenly at room temperature, adjust the solid content of the solvent to 12.0wt%, then add 30.00g of soybean meal powder, stir at room temperature for 3 minutes, form a soybean meal adhesive with a solid content of 30wt% and uniformity without particles, and obtain a high-temperature meal adhesive; Step (2) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250mL three-necked flask equipped with a stirrer and a condenser, heat to 80°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly for 30 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70°C, add epoxy resin E-54, stir for 30 minutes to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a stirring speed of 1000r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30 minutes to obtain a water-based epoxy resin with a solid content of 50%; Step (3) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42 g of L-Trp-BS and 0.75 g of an organic phosphorus compound (DOPO) and dissolve them in a three-necked flask filled with 45 mL of tetrahydrofuran, and stir them thoroughly. Put the mixed solution into a 110°C oil bath and react for 12 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a 60°C forced air oven overnight to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (4) Preparation of epoxy resin flame retardant material Dissolve 0.5 g of the synthetic flame retardant L-Trp-DOPO prepared in step (3) in 15 mL of anhydrous ethanol, fully disperse in a 70°C water bath for 15 min, add 30 mL of the epoxy resin prepared in step (2) and stir for 30 min, then add 3.4 mL of diethylenetriamine to the above mixed solution, remove the anhydrous ethanol with a vacuum filter for 5 min, pour the mixed solution into a preheated template, degas in an 80°C oven, place the sample in an 80°C oven for curing for 30 min, then switch the oven to a programmed temperature increase to 110°C and maintain for 3 h; Step (5) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (1), and add the epoxy resin flame retardant material obtained in step (4) at a single-sided adhesive coating amount of 265g / m 2 ; Use pre-pressing process: unit pressure 0.7MPa, cold pressing time 1h; hot pressing process: hot pressing temperature 125℃, unit pressure 0.7MPa, hot pressing time 780s, exhaust unit pressure 0.2MPa, exhaust time 120s to obtain high-performance green flame-retardant plywood.

[0029] Comparative Example 2

[0030] Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2.8 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15 mL of dimethyl sulfoxide (DMSO), and 5.6 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction solution was stirred at 25°C for 48 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography, and finally dried in a vacuum drying oven at 50°C for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder and grind it for 5 minutes, and pass it through a 240-mesh sieve to obtain high-temperature soybean meal powder. Take 89.55g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4wt%) prepared in step (1), add 10.45g of water, stir at room temperature to adjust the solid content of the solvent to 12.0wt%, then add 30.00g of soybean meal powder, stir at room temperature for 3 minutes to form a soybean meal adhesive with a solid content of 30wt% and uniformity without particles, and obtain a high-temperature meal adhesive; Step (3) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42 g of L-Trp-BS and 0.75 g of an organic phosphorus compound (DOPO) and dissolve them in a three-necked flask filled with 45 mL of tetrahydrofuran, and stir them thoroughly. Put the mixed solution into a 110°C oil bath and react for 12 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a 60°C forced air oven overnight to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (4) Preparation of epoxy resin flame retardant material Dissolve 0.8 g of the synthetic flame retardant L-Trp-DOPO prepared in step (3) in 15 mL of anhydrous ethanol, fully disperse in a 70°C water bath for 15 min, add 30 mL of epoxy resin and stir for 30 min, then add 3.4 mL of diethylenetriamine to the mixed solution, remove the anhydrous ethanol with a vacuum filter for 5 min, pour the mixed solution into a preheated template, degas in an 80°C oven, place the sample in an 80°C oven for curing for 30 min, then switch the oven to a programmed temperature increase to 110°C and maintain for 3 h; Step (5) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (2), and add the epoxy resin flame retardant material obtained in step (4), with a single-sided adhesive coating of 265g / m 2; Use pre-pressing process: unit pressure 0.7MPa, cold pressing time 1h; hot pressing process: hot pressing temperature 125℃, unit pressure 0.7MPa, hot pressing time 780s, exhaust unit pressure 0.2MPa, exhaust time 120s to obtain high-performance green flame-retardant plywood.

[0031] Comparison of detection experiments: The green flame retardant plywood obtained in Examples 1 to 4 and Comparative Example Products 1 and 2 were tested. The specific testing method is as follows: Gluing performance test According to the Chinese national standard GB / T 9846-2015, the dry strength and wet strength were determined using a SANS universal mechanical testing machine. Thirty specimens with a bonding area of ​​25 mm × 25 mm were cut out from each plywood. Ten specimens were tested for each strength (5 loose specimens and 5 tight specimens). The displacement control mode was used at a rate of 5.0 mm / min.

[0032] Cone Calorimetry (CCT) The flame retardant properties of L-Trp-DOPO compounds on epoxy resin matrix materials were studied by cone calorimeter testing. The working principle of cone calorimeter is based on the oxygen consumption principle, that is, the heat released by each unit of oxygen consumed when the flame retardant material burns is basically the same. In the experiment, by measuring the mass of oxygen consumed during the combustion process, parameters such as the heat release rate of the material can be calculated.

[0033] Table 1 Gluing performance test results

[0034] As shown in Table 1, Example 3 has the best bonding performance, while Comparative Example 2 is relatively poor. As the particle size of the soybean meal decreases, the bonding strength increases first and then decreases. The adhesive prepared from the soybean meal with a particle size of 160 mesh has the highest bonding performance, indicating that the optimal particle size is 160 mesh.

[0035] Table 2 Cone calorimetry test analysis results

[0036] It can be seen from Table 2 that Example 3 has the highest limiting oxygen index (LOI), while Comparative Example 1 is relatively poor. The higher the limiting oxygen index (LOI), the better the flame retardant performance of the material. The limiting oxygen index (LOI) increases with the increase of the content of the flame retardant L-Trp-DOPO. When the content is 7% (2.6 g), it reaches saturation, and further increasing the content has no obvious effect. Therefore, when the content of the flame retardant L-Trp-DOPO is 2.6 g, the flame retardant material has the best flame retardant performance, provides excellent performance in the process of preparing flame-retardant plywood, and has good potential.

Claims

1. A process for preparing high-performance green flame-retardant plywood, characterized in that: include: Synthesis of cross-linking agent furandicarboxylic acid-NHS active ester (FDCA-NHS), preparation of high-temperature meal adhesive, preparation of water-based epoxy resin, preparation of L-Trp-DOPO inorganic phosphorus-containing flame retardant, preparation of epoxy resin flame retardant materials, and preparation of high-performance green flame-retardant plywood.

2. The process for preparing a high-performance green flame-retardant plywood according to claim 1, characterized in that: Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2,5-furandicarboxylic acid (FDCA) and N-hydroxysuccinimide (NHS) are dissolved in dimethyl sulfoxide (DMSO), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) is added to the above solution, the mixed reaction liquid is stirred at a certain temperature, after the reaction is completed, dimethyl sulfoxide (DMSO) is washed away by an extraction method, the reaction product is purified by column chromatography, and finally dried in a vacuum drying oven at a certain temperature for use; Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder for grinding and sieving to obtain high-temperature soybean meal powder. Add water to the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution obtained in step (1), stir evenly at room temperature, adjust the solid content of the solvent, then add the soybean meal powder, stir at room temperature to form a uniform soybean meal adhesive without particles, and obtain a high-temperature meal adhesive. Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a three-necked flask equipped with a stirrer and a condenser, heat and heat up, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip into the flask, mix evenly and heat up to obtain a non-ionic epoxy emulsifier, lower the temperature, add epoxy resin E-54, stir to mix evenly with the epoxy emulsifier, and then slowly drip distilled water at a certain stirring speed. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for a period of time to obtain a water-based epoxy resin; Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant A certain amount of L-Trp-BS and an organic phosphorus compound (DOPO) were weighed and dissolved in a three-necked flask filled with tetrahydrofuran, and the mixture was fully stirred. The mixed solution was placed in an oil bath and reacted for a period of time. The precipitated dark yellow product was washed with ethanol and deionized water, and dried overnight in a forced air oven at a certain temperature to obtain an L-Trp-DOPO inorganic phosphorus-containing flame retardant. Step (5) Preparation of epoxy resin flame retardant material The flame retardant L-Trp-DOPO prepared in step (4) is dissolved in anhydrous ethanol, fully dispersed in a water bath for a period of time, the epoxy resin obtained in step (3) is added and stirred, and then diethylenetriamine is added to the mixed solution, and the anhydrous ethanol is removed by vacuum filter. After a period of time, the mixed solution is poured into a preheated template, and the bubbles are removed in an oven. The sample is placed in an oven for curing for a period of time, and then the oven is switched to a programmed temperature rise for storage; Step (6) Preparation of high-performance green flame-retardant plywood Use five-layer eucalyptus veneer, use the high-temperature cake adhesive obtained in step (2), add the epoxy resin flame retardant material obtained in step (5), and set an appropriate single-sided glue coating amount; use a pre-pressing process: set a unit pressure, and cold press for a period of time; Hot pressing process: set the hot pressing temperature and unit pressure, hot press for a period of time, exhaust the air at a certain unit pressure, and after the exhaust time is completed, high-performance green flame-retardant plywood is obtained.

3. The process for preparing a high-performance green flame-retardant plywood according to claim 2, characterized in that: Step (1) Synthesis of crosslinking agent furandicarboxylic acid-NHS active ester (FDCA-NHS) 2.8-3.1 mmol of 2,5-furandicarboxylic acid (FDCA) and 5.6-7.1 mmol of N-hydroxysuccinimide (NHS) were dissolved in 15-23 mL of dimethyl sulfoxide (DMSO), and 5.6-6.9 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added to the above solution. The mixed reaction liquid was stirred at 25-35°C for 48-56 hours. After the reaction was completed, dimethyl sulfoxide (DMSO) was washed away by extraction, and the reaction product was purified by column chromatography. Finally, it was dried in a vacuum drying oven at 50-60°C for use.

4. The process for preparing a high-performance green flame-retardant plywood according to claim 3, characterized in that: Step (2) Preparation of high temperature meal adhesive Put the flake soybean meal into a grinder for pulverization for 5-8 minutes, and pass it through a 160-200 mesh sieve to obtain high-temperature soybean meal powder. Take 89.55-91.65 g of the cross-linking agent modifier furandicarboxylic acid-NHS active ester (FDCA-NHS) solution (13.4-15.6 wt%) obtained in step (1), add 10.45-11.95 g of water thereto, stir evenly at room temperature, adjust the solid content of the solvent to 12.0-13.0 wt%, then add 30.00-35.00 g of soybean meal powder, stir at room temperature for 3-5 minutes, and form a soybean meal adhesive with a solid content of 30-35 wt% and no particles, thereby obtaining a high-temperature meal adhesive.

5. The process for preparing a high-performance green flame-retardant plywood according to claim 4, characterized in that: Step (3) Preparation of waterborne epoxy resin Add epoxy resin E-31 and polyethylene glycol (PEG) to a 250-300 mL three-necked flask equipped with a stirrer and a condenser, heat to 80-90°C, stir and mix evenly after melting, dissolve potassium persulfate in water and slowly drip it into the flask, mix evenly for 30-35 minutes and then heat to obtain a non-ionic epoxy emulsifier, lower the temperature to 70-75°C, add epoxy resin E-54, stir for 30-35 minutes to mix it and the epoxy emulsifier evenly, and then slowly drip distilled water at a stirring speed of 1000-1200 r / min. When the viscosity of the system suddenly decreases, the system changes from W / O to O / W. After adding water, continue stirring for 30-35 minutes to obtain a water-based epoxy resin with a solid content of 50-52%.

6. The process for preparing a high-performance green flame-retardant plywood according to claim 5, characterized in that: Step (4) Preparation of L-Trp-DOPO Inorganic Phosphorus-containing Flame Retardant Weigh 1.42-1.86 g L-Trp-BS and 0.75-1 g organophosphorus compound (DOPO) and dissolve them in a three-necked flask containing 45-55 mL tetrahydrofuran, and stir them thoroughly. Put the mixed solution into an oil bath at 110-120 °C and react for 12-14 h. Wash the precipitated dark yellow product with ethanol and deionized water, and dry it in a forced air oven at 60-65 °C overnight to obtain L-Trp-DOPO inorganic phosphorus-containing flame retardant.

7. The process for preparing a high-performance green flame-retardant plywood according to claim 6, characterized in that: Step (5) Preparation of epoxy resin flame retardant material The flame retardant L-Trp-DOPO prepared in step (4) is dissolved in 15-20 mL of anhydrous ethanol and fully dispersed in a 70-75°C water bath for 15-20 min. 30-35 mL of the epoxy resin obtained in step (3) is added and stirred for 30-45 min. Then 3.4-4.2 mL of diethylenetriamine is added to the mixed solution. The anhydrous ethanol is removed by vacuum filter for 5-7 min. The mixed solution is poured into a preheated template and degassed in an oven at 80-90°C. The sample is placed in an oven at 80-90°C for curing for 30-35 min. The oven is then switched to a programmed temperature rise to 110-115°C and maintained for 3-4 h.

8. The process for preparing a high-performance green flame-retardant plywood according to claim 7, characterized in that: Step (6) Preparation of high-performance green flame-retardant plywood Use five layers of eucalyptus veneer, use the high temperature cake adhesive obtained in step (2), and add the epoxy resin flame retardant material obtained in step (5) at the same time, and the single-sided glue coating amount is (260±10) g / m 2 ; Use pre-pressing process: unit pressure (0.7±0.1) MPa, cold pressing time 1~1.5h; hot pressing process: hot pressing temperature is 125~150℃, unit pressure (0.7±0.1) MPa, hot pressing time is 780~800s, exhaust unit pressure is (0.2±0.1) MPa, exhaust time is 120~130s, to obtain high-performance green flame-retardant plywood.

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