Composite material prepared from melamine waste and preparation method thereof
By treating melamine waste through a combination of steam explosion and enzyme catalysis, a multifunctional composite material was prepared, which solved the problem of the difficult efficient recycling of melamine waste and achieved efficient reduction of formaldehyde migration risk and performance improvement.
Patent Information
- Application Number
- CN202510880767.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-09-05
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Melamine waste generated during the production and product processing process is difficult to recycle efficiently, and there is a risk of formaldehyde migration. Traditional treatment methods are inefficient and may cause secondary pollution.
Steam explosion treatment was used to destroy the structure of melamine waste, and detoxification treatment was carried out by combining enzyme catalysis reaction with ionic liquid-water system. Cellulose and PEEK were modified with silane coupling agent, and multifunctional microspheres were formed through electrostatic self-assembly to prepare composite materials.
It achieves deep purification of melamine waste, reduces the risk of formaldehyde migration, improves the utilization rate of waste and the performance of composite materials, and avoids the defects of traditional methods.
Smart Images
Figure BDA0005472327480000111
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of polymer material preparation, and relates to a composite material prepared from melamine waste and a preparation method thereof. Background Art
[0002] Melamine resin, a thermosetting polymer material, is widely used in the manufacture of tableware, electrical components, and decorative panels due to its excellent heat resistance, surface hardness, and decorative properties. However, the waste generated during its production and product processing contains incompletely reacted monomers and cross-linked network structures, making it difficult to efficiently recycle using conventional methods. Traditional treatment methods often involve simple crushing and use as low-end fillers, but this has problems such as low waste utilization and severe performance degradation of recycled products. In particular, when used in food contact materials, the risk of residual formaldehyde migration has become a key bottleneck restricting its high-value utilization.
[0003] Existing technologies for detoxifying melamine waste rely primarily on single physical or chemical methods. For example, steam treatment can reduce free formaldehyde levels to a certain extent. While chemical depolymerization can break down the resin network, it requires the use of strong acids or high temperatures, which not only causes severe equipment corrosion but also generates secondary pollution. Furthermore, while directly introducing adsorbents (such as activated carbon and zeolite) can partially adsorb formaldehyde, the effect is limited, and adding large amounts of adsorbents increases costs. Summary of the Invention
[0004] To address the shortcomings of the existing technology, the present invention aims to provide a composite material prepared from melamine waste and its preparation method. First, the melamine waste is steam-exploded to destroy its internal structure and remove surface activity. The waste is then further treated using an enzyme-catalyzed reaction and an ionic liquid-water system. Carboxylated cellulose and acid-etched polyetheretherketone are modified with a silane coupling agent. Through electrostatic self-assembly and crosslinking of chitosan and polyethyleneimine, a multifunctional microsphere filler is prepared. Finally, the modified melamine waste is mixed with various functional materials, combined with a novel resin and additives to form a uniform slurry. The composite material is then vacuum-degassing and mold-pressed to produce a composite material that meets practical production needs.
[0005] To achieve this object, the present invention adopts the following technical solutions:
[0006] In a first aspect, the present invention provides a method for preparing a composite material using melamine waste, the method comprising:
[0007] S1, placing the melamine waste in a steam explosion tank and then releasing the pressure to normal pressure instantly, and immediately immersing the waste in a citric acid solution after the explosion to obtain a deactivated waste;
[0008] S2, dispersing laccase and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in sodium acetate buffer, adding the deactivated waste to the sodium acetate buffer, and then adding catalase to obtain a deactivated waste, and mixing the deactivated waste, 1-butyl-3-methylimidazolium acetate, and deionized water to obtain a detoxified waste;
[0009] S3, mixing the chitosan solution and polyethyleneimine to obtain a chitosan solution-polyethyleneimine mixture, then adding the chitosan solution-polyethyleneimine mixture to a sodium tripolyphosphate solution, allowing the mixture to stand and freeze-drying to obtain polyethyleneimine-chitosan microspheres;
[0010] S4, uniformly mixing the detoxified waste, polyethyleneimine-chitosan microspheres, modified carboxylated cellulose and modified PEEK, then adding new melamine resin and castor oil to obtain a slurry, injecting the slurry into a mold cavity and performing a pressing process to obtain a composite material prepared using melamine waste.
[0011] Specifically include:
[0012] A1, γ-glycidyloxypropyltrimethoxysilane, ethanol aqueous solution and triethylamine are mixed and stirred, and then carboxylated cellulose is added, and the mixture is refluxed at 70-75° C., washed by centrifugation and dried to obtain modified carboxylated cellulose;
[0013] A2, mixing PEEK powder with concentrated sulfuric acid, adjusting the temperature to 60-65°C with stirring, filtering, washing, and drying to obtain acid-etched PEEK, dispersing the acid-etched PEEK in KH550 ethanol solution, and curing at 120-125°C after ultrasonic treatment to obtain modified PEEK;
[0014] S1, placing melamine waste in a steam explosion tank and then releasing the pressure to normal pressure instantly, immediately immersing the waste in a citric acid solution after the explosion and transferring it to a water bath at a first temperature, while simultaneously performing ultrasonic treatment, washing it to neutrality after the ultrasonic treatment and vacuum drying it to obtain a deactivated waste;
[0015] S2, dispersing laccase and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in a sodium acetate buffer, adding the deactivated waste to the sodium acetate buffer, adjusting the temperature to a second temperature and oscillating, adjusting the pH to 7-7.3 using a sodium hydroxide solution, then adding catalase and continuing to oscillate, washing and drying to obtain a tandem-treated waste, mixing the tandem-treated waste, 1-butyl-3-methylimidazole acetate, and deionized water, adjusting the temperature to a third temperature and ultrasonically treating, centrifuging, washing, vacuum drying, and pulverizing to obtain a detoxified waste;
[0016] S3, mixing the chitosan solution and polyethyleneimine, adjusting the temperature to a fourth temperature and stirring to obtain a chitosan solution-polyethyleneimine mixture, then adding the chitosan solution-polyethyleneimine mixture to the sodium tripolyphosphate solution, allowing to stand, centrifuging, and freeze-drying to obtain polyethyleneimine-chitosan microspheres;
[0017] S4, mixing the detoxified waste, polyethyleneimine-chitosan microspheres, modified carboxylated cellulose and modified PEEK evenly, then adding new melamine resin and castor oil, mixing evenly and vacuum degassing to obtain a slurry, injecting the slurry into a mold cavity and performing a pressing process to obtain a composite material prepared using melamine waste.
[0018] Carboxylated cellulose is surface-modified using γ-glycidyloxypropyltrimethoxysilane (GPTES). The epoxy groups of GPTES open under weakly alkaline conditions and undergo esterification with carboxyl groups on the cellulose surface, forming stable covalent bonds. Simultaneously, the methoxy groups at the silane terminals hydrolyze in aqueous ethanol to generate silanol groups, which further condense with cellulose hydroxyl groups to form a dense siloxane coating. This dual bonding mechanism not only enhances the interfacial compatibility between cellulose and the matrix resin but also inhibits the diffusion pathways of formaldehyde molecules. Acid etching of polyetheretherketone (PEEK) introduces sulfonic acid groups onto its surface through the strong oxidizing properties of concentrated sulfuric acid, disrupting its inert surface and increasing its roughness. Subsequently, the amino groups of the silane coupling agent bond to the sulfonic acid groups through acid-base interactions. Simultaneously, the hydrolyzed ethoxy groups of the silane condense with the residual hydroxyl groups on the PEEK surface to form chemical anchor points, enhancing the interfacial bonding strength with the melamine resin and blocking the formaldehyde escape pathways caused by microcrack propagation.
[0019] The melamine waste first undergoes a steam explosion treatment. High-temperature, high-pressure steam penetrates into the internal pores and cross-linked networks of the waste. During instantaneous pressure release, the shear force generated by the rapid vaporization and expansion of water can physically tear apart the three-dimensional cross-linked structure of the melamine resin, exposing the unreacted formaldehyde monomers and oligomers encapsulated inside. The exploded waste is then immersed in a citric acid solution. In an acidic environment, the carboxyl groups of citric acid protonate the methylene bridge bonds in the melamine resin, weakening its stability and causing some cross-links to break, further releasing bound formaldehyde. At the same time, citric acid, as a chelating agent, can complex the metal catalysts remaining in the resin, blocking their catalytic effect on formaldehyde release. Ultrasonic treatment accelerates the diffusion of citric acid molecules into the deep layers of the waste and promotes the peeling of broken molecular chain fragments, forming a porous structure that provides a larger specific surface area for subsequent enzymatic hydrolysis reactions.
[0020] Laccase and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) act synergistically to attack the methylene bridges and residual hydroxymethyl groups in melamine waste through a redox reaction. Laccase catalyzes the generation of cationic radicals from ABTS. These reactive intermediates can abstract hydrogen atoms from the methylene bridges, triggering carbon chain scission and depolymerizing the cross-linked network into short, aldehyde-containing fragments. Subsequently, catalase selectively decomposes the hydrogen peroxide produced in the reaction under near-neutral conditions, preventing the accumulation of its oxidation byproducts (such as formic acid) that could inhibit enzyme activity. It also further oxidizes the formaldehyde intermediate to carbon dioxide and water, achieving deep mineralization of the formaldehyde. An ionic liquid (1-butyl-3-methylimidazolium acetate), leveraging its strong polarity and hydrogen bond-breaking capabilities, penetrates the pores of the depolymerized melamine fragments, dissolving incompletely degraded oligomers and physically adsorbed formaldehyde. Its imidazolium cation forms a π-π interaction with the formaldehyde molecule, while the acetate anion captures the positively charged degradation products through electrostatic attraction to form a soluble complex, thereby achieving deep purification of the waste.
[0021] Chitosan and polyethyleneimine (PEI) form functional microspheres through electrostatic interactions and intermolecular crosslinking. The amino groups on the chitosan molecular chain are protonated under acidic conditions, carrying a positive charge. PEI, rich in primary and secondary amine groups, also exhibits a strong positive charge. When the two are mixed, the amine groups of PEI interact with the hydroxyl and amino groups of chitosan through hydrogen bonds and van der Waals forces, forming a dynamic physical crosslinked network. Negatively charged sodium tripolyphosphate is then introduced as a crosslinker. Its phosphate anions ionically crosslink with the cationic groups of chitosan and PEI through electrostatic attraction to form microspheres. Incompletely crosslinked regions within the microspheres form through-hole channels due to ice crystal growth during freeze-drying. The resulting microspheres exhibit a hierarchical porous structure, and the porous network with a high specific surface area provides numerous adsorption sites for formaldehyde molecules. The free amine groups of PEI react with formaldehyde through nucleophilic addition to form a Schiff base, while the amino groups of chitosan capture protonated formaldehyde molecules through electrostatic interactions, achieving a synergistic adsorption-immobilization mechanism.
[0022] As a preferred technical solution of the present invention, in A1, the mass ratio of γ-glycidyloxypropyltrimethoxysilane, ethanol aqueous solution, triethylamine and carboxylated cellulose is 30:970:5:(10-13), for example, it can be 30:970:5:(10.0, 10.3, 10.6, 10.9, 11.2, 11.5, 11.8, 12.1, 12.4, 12.7 or 13.0), but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0023] In some optional examples, the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 4:1.
[0024] In some optional examples, the reflux reaction time is 6-7h, for example, it can be 6.0h, 6.1h, 6.2h, 6.3h, 6.4h, 6.5h, 6.6h, 6.7h, 6.8h, 6.9h or 7.0h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0025] As a preferred technical solution of the present invention, in A2, the mass ratio of the PEEK powder to concentrated sulfuric acid is 1:10.
[0026] In some optional examples, the mass fraction of KH550 in the KH550 ethanol solution is 5 wt.%.
[0027] In some optional examples, the mass ratio of the acid-etched PEEK to the KH550 ethanol solution is 1:20.
[0028] As a preferred technical solution of the present invention, in S1, the conditions of the steam explosion tank are set to a pressure of 1.8-2.0 MPa, for example, 1.80 MPa, 1.82 MPa, 1.84 MPa, 1.86 MPa, 1.88 MPa, 1.90 MPa, 1.92 MPa, 1.94 MPa, 1.96 MPa, 1.98 MPa or 2.00 MPa, and a temperature of 200-210°C, for example, 200°C, 201°C, 202°C, 203°C, 204°C, 205°C, 206°C, 207°C, 208°C, 209°C or 210°C, but are not limited to the listed values, and other values not listed within the numerical range are also applicable.
[0029] In some optional examples, the holding time is 8-10 min, for example, it can be 8.0 min, 8.2 min, 8.4 min, 8.6 min, 8.8 min, 9.0 min, 9.2 min, 9.4 min, 9.6 min, 9.8 min or 10.0 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0030] In some optional examples, the concentration of the citric acid solution is 0.1 M, and contains 5 wt.% of hydrogen peroxide.
[0031] In some optional examples, the first temperature is 70-75°C, for example, it can be 70.0°C, 70.5°C, 71.0°C, 71.5°C, 72.0°C, 72.5°C, 73.0°C, 73.5°C, 74.0°C, 74.5°C or 75.0°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0032] In some optional examples, the ultrasonic treatment time is 30-35 min, for example, it can be 30.0 min, 30.5 min, 31.0 min, 31.5 min, 32.0 min, 32.5 min, 33.0 min, 33.5 min, 34.0 min, 34.5 min or 35.0 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0033] As a preferred technical solution of the present invention, in S2, the mass ratio of the laccase, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, sodium acetate buffer, deactivated waste and catalase is (0.57-0.6): (0.054-0.06): 2000: (860-880): (0.17-0.19), for example, it can be (0.57, 0.58, 0.59 or 0 .60): (0.054, 0.055, 0.056, 0.057, 0.058, 0.059 or 0.060): 2000: (860, 862, 864, 866, 868, 870, 872, 874, 876, 878 or 880): (0.17, 0.18 or 0.19), but are not limited to the listed values, other values not listed within the numerical range are also applicable.
[0034] In some optional examples, the activity of the laccase is ≥15 U / mg.
[0035] In some optional examples, the pH of the sodium acetate buffer is 4.5.
[0036] In some optional examples, the second temperature is 50-55°C, for example, it can be 50.0°C, 50.5°C, 51.0°C, 51.5°C, 52.0°C, 52.5°C, 53.0°C, 53.5°C, 54.0°C, 54.5°C or 55.0°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0037] In some optional examples, the time of the second temperature oscillation is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0038] In some optional examples, the concentration of the sodium hydroxide solution is 1M.
[0039] In some optional examples, the catalase activity is ≥5000 U / mg.
[0040] In some optional examples, the continued oscillation time is 1-2h, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0041] In some optional examples, the mass ratio of the jointly treated waste, 1-butyl-3-methylimidazole acetate and deionized water is (800-810):200:800, for example, it can be (800, 801, 802, 803, 804, 805, 806, 807, 808, 809 or 810):200:800, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
[0042] In some optional examples, the third temperature is 60-65°C, for example, it can be 60.0°C, 60.5°C, 61.0°C, 61.5°C, 62.0°C, 62.5°C, 63.0°C, 63.5°C, 64.0°C, 64.5°C or 65.0°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0043] In some optional examples, the ultrasonic treatment time is 40-45 min, for example, it can be 40.0 min, 40.5 min, 41.0 min, 41.5 min, 42.0 min, 42.5 min, 43.0 min, 43.5 min, 44.0 min, 44.5 min or 45.0 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0044] In some optional examples, the vacuum drying temperature is 120-130°C, for example, it can be 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C or 130°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
[0045] As a preferred technical solution of the present invention, in S3, the mass ratio of chitosan, glacial acetic acid and deionized water in the chitosan solution is 2:1:97.
[0046] In some optional examples, the mass ratio of the chitosan solution to polyethyleneimine is 100:(1-2), for example, it can be 100:(1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0), but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
[0047] In some optional examples, the fourth temperature is 40-45°C, for example, it can be 40.0°C, 40.5°C, 41.0°C, 41.5°C, 42.0°C, 42.5°C, 43.0°C, 43.5°C, 44.0°C, 44.5°C or 45.0°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0048] In some optional examples, the stirring time at the fourth temperature is 1-2h, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0049] In some optional examples, the mass ratio of the chitosan solution-polyethyleneimine mixed solution to the sodium tripolyphosphate solution is 1:1.
[0050] In some optional examples, the mass fraction of the sodium tripolyphosphate solution is 2 wt.%.
[0051] In some optional examples, the standing time is 1-2h, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0052] As a preferred technical solution of the present invention, in S4, the mass ratio of the detoxified waste, polyethyleneimine-chitosan microspheres, modified carboxylated cellulose, modified PEEK, new melamine resin and castor oil is (550-570): (30-35): (70-78): (15-20): (380-400): (20-30), for example, it can be (550, 552, 554, 556, 558, 560, 562, 564, 566, 568 or 570): (30.0, 30.5, 31.0, 31.5, 32.0, 32.5, 33.0, 33.5, 34.0, 34.5 or 35.0) : (70.0, 70.8, 71.6, 72.4, 73.2, 74.0, 74.8, 75.6, 76.4, 77.2 or 78.0): (15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5 or 20.0): (380, 382, 384, 386, 388, 390, 392, 394, 396, 398 or 400): (20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30), but are not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0053] In some optional examples, the new melamine resin is a water-soluble melamine resin with a solid content of 40%, and the technical indicators of the water-soluble melamine resin comply with GB 4806.7-2016.
[0054] In some optional examples, the upper mold temperature of the pressing process is 160-165°C, for example, it can be 160.0°C, 160.5°C, 161.0°C, 161.5°C, 162.0°C, 162.5°C, 163.0°C, 163.5°C, 164.0°C or 164.5°C and 165.0°C, and the lower mold temperature is 300-305°C, for example, it can be 300.0°C, 300.5°C, 301.0°C, 301.5°C, 302.0°C, 302.5°C, 303.0°C, 303.5°C, 304.0°C or 304.5°C and 305.0°C, and the pressure is first increased to 5MPa and maintained for 3 minutes, and then pressurized to 15MPa and maintained for 10 minutes, but it is not limited to the listed values, and other values not listed within this numerical range are also applicable.
[0055] In a second aspect, the present invention provides a composite material prepared from melamine waste by the preparation method described in the first aspect.
[0056] Compared with the prior art, the present invention has the following beneficial effects: (1) the physical effect of steam explosion is used to tear the cross-linked structure, exposing the internal methylene bridge bonds and hydroxymethyl groups, and then the bound formaldehyde is converted into a free state through the laccase-mediator system, while avoiding excessive damage to the melamine main chain. With the help of the selectivity advantage of the enzymatic hydrolysis reaction, the integrity of the material skeleton is retained while releasing formaldehyde, avoiding the ineffective treatment of encapsulated formaldehyde by traditional methods; (2) the multi-level pores of the polyethyleneimine-chitosan microspheres provide high specific surface area adsorption sites, and the amino groups enriched on the surface form stable imine bonds with formaldehyde through nucleophilic addition to achieve chemical fixation. At the same time, catalase further oxidizes the formaldehyde intermediate into carbon dioxide and water, avoiding the desorption risk of traditional adsorbents; (3) the covalently bonded interface between the modified cellulose and the melamine matrix forms a dense three-dimensional network, which limits the migration of formaldehyde molecules through the steric effect; the micro-nano rough structure on the acid-etched PEEK surface enhances the interfacial bonding force through mechanical interlocking, blocking the formaldehyde escape channel formed by the expansion of microcracks. DETAILED DESCRIPTION
[0057] The technical solutions of the present invention are described in detail below with reference to specific embodiments. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.
[0058] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products and have not been subjected to any further purification treatment.
[0059] Example 1
[0060] This embodiment provides a composite material prepared using melamine waste and a preparation method thereof, wherein the preparation method specifically comprises the following steps:
[0061] A1, 30 g of γ-glycidyloxypropyltrimethoxysilane, 970 g of ethanol aqueous solution and 5 g of triethylamine were mixed and stirred, and then 10 g of carboxylated cellulose was added. The mixture was refluxed at 70°C for 6 h, washed by centrifugation and dried to obtain modified carboxylated cellulose;
[0062] A2, 1g PEEK powder was mixed with 10g concentrated sulfuric acid, the temperature was adjusted to 60℃, stirred, filtered, washed and dried to obtain acid-etched PEEK, 1g acid-etched PEEK was dispersed in 20g KH550 ethanol solution, ultrasonically treated and cured at 120℃ to obtain modified PEEK;
[0063] S1, placing melamine waste in a steam explosion tank at 1.8 MPa and 200°C for 8 minutes, then instantly releasing the pressure to normal pressure, immediately immersing the waste in a 0.1 M citric acid solution after explosion and transferring it to a 70°C water bath, while simultaneously subjecting it to ultrasonic treatment for 30 minutes. After the ultrasonic treatment, washing the waste to neutrality and vacuum drying the resulting deactivated waste; the citric acid solution contains 5 wt.% hydrogen peroxide;
[0064] S2, dispersing 0.57 g of laccase and 0.054 g of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in 2000 g of sodium acetate buffer, wherein the pH of the sodium acetate buffer is 4.5, adding 860 g of deactivated waste to the sodium acetate buffer, adjusting the temperature to 50° C. and shaking for 2 h, adjusting the pH to 7 with sodium hydroxide solution, adding 0.17 g of catalase, and continuing to shake for 1 h, washing and drying to obtain a detoxified waste, mixing 800 g of the detoxified waste, 200 g of 1-butyl-3-methylimidazole acetate, and 800 g of deionized water, adjusting the temperature to 60° C. and ultrasonically treating for 40 min, centrifuging and washing, drying under vacuum at 120° C., and pulverizing to obtain a detoxified waste; the laccase activity is ≥15 U / mg, and the catalase activity is ≥5000 U / mg;
[0065] S3, mixing 100 g of chitosan solution with 1 g of polyethyleneimine, wherein the mass ratio of chitosan, glacial acetic acid, and deionized water in the chitosan solution is 2:1:97, adjusting the temperature to 40°C and stirring for 1 hour to obtain a chitosan solution-polyethyleneimine mixed solution, then adding 1 g of the chitosan solution-polyethyleneimine mixed solution to 1 g of a 2 wt.% sodium tripolyphosphate solution, letting it stand for 1 hour, centrifuging, and freeze-drying to obtain polyethyleneimine-chitosan microspheres;
[0066] S4, 550g of detoxified waste, 30g of polyethyleneimine-chitosan microspheres, 70g of modified carboxylated cellulose and 15g of modified PEEK are mixed evenly, and then 380g of new melamine resin and 20g of castor oil are added, mixed evenly and vacuum degassed to obtain a slurry, wherein the new melamine resin is a water-soluble melamine resin with a solid content of 40%, and the technical indicators of the water-soluble melamine resin comply with GB4806.7-2016; the slurry is injected into the mold cavity and a pressing process is performed, the upper mold temperature of the pressing process is 160°C, the lower mold temperature is 300°C, the pressure is first increased to 5MPa and maintained for 3min, and then the pressure is increased to 15MPa and maintained for 10min to obtain a composite material prepared using melamine waste.
[0067] Example 2
[0068] This embodiment provides a composite material prepared using melamine waste and a preparation method thereof, wherein the preparation method specifically comprises the following steps:
[0069] A1, 30 g of γ-glycidyloxypropyltrimethoxysilane, 970 g of ethanol aqueous solution and 5 g of triethylamine were mixed and stirred, and then 13 g of carboxylated cellulose was added. The mixture was refluxed at 75°C for 7 h, and then centrifuged, washed and dried to obtain modified carboxylated cellulose;
[0070] A2, 1g PEEK powder was mixed with 10g concentrated sulfuric acid, the temperature was adjusted to 65℃, stirred, filtered, washed, and dried to obtain acid-etched PEEK, 1g acid-etched PEEK was dispersed in 20g KH550 ethanol solution, ultrasonically treated, and cured at 122℃ to obtain modified PEEK;
[0071] S1, placing melamine waste in a steam explosion tank at 1.9 MPa and 202°C for 9 minutes, then instantly releasing the pressure to normal pressure, immediately immersing the waste in a 0.1 M citric acid solution after explosion and transferring it to a 75°C water bath, while simultaneously subjecting it to ultrasonic treatment for 35 minutes. After the ultrasonic treatment, washing the waste to neutrality and vacuum drying the resulting deactivated waste; the citric acid solution contains 5 wt.% hydrogen peroxide;
[0072] S2, dispersing 0.6 g of laccase and 0.06 g of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in 2000 g of sodium acetate buffer, wherein the pH of the sodium acetate buffer is 4.5, adding 880 g of deactivated waste to the sodium acetate buffer, adjusting the temperature to 55° C. and shaking for 2.2 h, adjusting the pH to 7.3 with sodium hydroxide solution, adding 0.19 g of catalase, and continuing to shake for 2 h, washing and drying to obtain a detoxified waste, mixing 810 g of the detoxified waste, 200 g of 1-butyl-3-methylimidazole acetate, and 800 g of deionized water, adjusting the temperature to 65° C. and ultrasonically treating for 41 min, centrifuging and washing, drying under vacuum at 122° C., and pulverizing to obtain a detoxified waste; the laccase activity is ≥15 U / mg, and the catalase activity is ≥5000 U / mg;
[0073] S3, mixing 100 g of chitosan solution with 1.3 g of polyethyleneimine, wherein the mass ratio of chitosan, glacial acetic acid, and deionized water in the chitosan solution is 2:1:97, adjusting the temperature to 41°C and stirring for 2 h to obtain a chitosan solution-polyethyleneimine mixture, then adding 1 g of the chitosan solution-polyethyleneimine mixture to 1 g of a 2 wt.% sodium tripolyphosphate solution, allowing to stand for 1.3 h, centrifuging, and freeze-drying to obtain polyethyleneimine-chitosan microspheres;
[0074] S4, 570g of detoxified waste, 33g of polyethyleneimine-chitosan microspheres, 78g of modified carboxylated cellulose and 20g of modified PEEK are mixed evenly, and then 390g of new melamine resin and 22g of castor oil are added, mixed evenly and vacuum degassed to obtain a slurry, wherein the new melamine resin is a water-soluble melamine resin with a solid content of 40%, and the technical indicators of the water-soluble melamine resin comply with GB4806.7-2016; the slurry is injected into the mold cavity and a pressing process is performed, the upper mold temperature of the pressing process is 165°C, the lower mold temperature is 305°C, the pressure is first increased to 5MPa and maintained for 3min, and then the pressure is increased to 15MPa and maintained for 10min, to obtain a composite material prepared using melamine waste.
[0075] Example 3
[0076] This embodiment provides a composite material prepared using melamine waste and a preparation method thereof, wherein the preparation method specifically comprises the following steps:
[0077] A1, 30 g of γ-glycidyloxypropyltrimethoxysilane, 970 g of ethanol aqueous solution and 5 g of triethylamine were mixed and stirred, and then 12 g of carboxylated cellulose was added. The mixture was refluxed at 71°C for 6.3 h, and then centrifuged, washed and dried to obtain modified carboxylated cellulose;
[0078] A2, 1g PEEK powder was mixed with 10g concentrated sulfuric acid, the temperature was adjusted to 61℃, stirred, filtered, washed, and dried to obtain acid-etched PEEK, 1g acid-etched PEEK was dispersed in 20g KH550 ethanol solution, ultrasonically treated, and cured at 125℃ to obtain modified PEEK;
[0079] S1, placing melamine waste in a 2.0 MPa, 210° C. steam explosion tank for 10 minutes, then instantly releasing the pressure to normal pressure, immediately immersing the waste in a 0.1 M citric acid solution after explosion and transferring it to a 71° C. water bath, while simultaneously ultrasonically treating it for 33 minutes. After the ultrasonic treatment, washing it to neutrality and vacuum drying it to obtain a deactivated waste; the citric acid solution contains 5 wt.% hydrogen peroxide;
[0080] S2, dispersing 0.58 g of laccase and 0.057 g of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in 2000 g of sodium acetate buffer, wherein the pH of the sodium acetate buffer is 4.5, adding 870 g of deactivated waste to the sodium acetate buffer, adjusting the temperature to 51° C. and shaking for 3 h, adjusting the pH to 7.1 with sodium hydroxide solution, adding 0.18 g of catalase and continuing to shake for 1.3 h, washing and drying to obtain a detoxified waste, mixing 803 g of the detoxified waste, 200 g of 1-butyl-3-methylimidazole acetate, and 800 g of deionized water, adjusting the temperature to 61° C. and ultrasonically treating for 45 min, centrifuging and washing, drying under vacuum at 130° C., and pulverizing to obtain a detoxified waste; the laccase activity is ≥15 U / mg, and the catalase activity is ≥5000 U / mg;
[0081] S3, mixing 100 g of chitosan solution with 2 g of polyethyleneimine, wherein the mass ratio of chitosan, glacial acetic acid, and deionized water in the chitosan solution is 2:1:97, adjusting the temperature to 45°C and stirring for 1.3 h to obtain a chitosan solution-polyethyleneimine mixture, then adding 1 g of the chitosan solution-polyethyleneimine mixture to 1 g of a 2 wt.% sodium tripolyphosphate solution, letting it stand for 2 h, then centrifuging and freeze-drying to obtain polyethyleneimine-chitosan microspheres;
[0082] S4, 560g of detoxified waste, 35g of polyethyleneimine-chitosan microspheres, 72g of modified carboxylated cellulose and 16g of modified PEEK are mixed evenly, and then 400g of new melamine resin and 30g of castor oil are added, mixed evenly and vacuum degassed to obtain a slurry, wherein the new melamine resin is a water-soluble melamine resin with a solid content of 40%, and the technical indicators of the water-soluble melamine resin comply with GB4806.7-2016; the slurry is injected into the mold cavity and a pressing process is performed, the upper mold temperature of the pressing process is 162°C, the lower mold temperature is 303°C, the pressure is first increased to 5MPa and maintained for 3min, and then the pressure is increased to 15MPa and maintained for 10min to obtain a composite material prepared using melamine waste.
[0083] Example 4
[0084] This embodiment provides a composite material prepared using melamine waste and a preparation method thereof, wherein the preparation method specifically comprises the following steps:
[0085] A1, 30 g of γ-glycidyloxypropyltrimethoxysilane, 970 g of ethanol aqueous solution and 5 g of triethylamine were mixed and stirred, and then 11 g of carboxylated cellulose was added. The mixture was refluxed at 73°C for 6.6 h, and then centrifuged, washed and dried to obtain modified carboxylated cellulose;
[0086] A2, 1g PEEK powder was mixed with 10g concentrated sulfuric acid, the temperature was adjusted to 64℃, stirred, filtered, washed and dried to obtain acid-etched PEEK, 1g acid-etched PEEK was dispersed in 20g KH550 ethanol solution, ultrasonically treated and cured at 124℃ to obtain modified PEEK;
[0087] S1, placing melamine waste in a steam explosion tank at 1.8 MPa and 207°C for 8.5 minutes, then instantly releasing the pressure to normal pressure, immediately immersing the waste in a 0.1 M citric acid solution after explosion and transferring it to a 73°C water bath, while simultaneously subjecting it to ultrasonic treatment for 31 minutes. After the ultrasonic treatment, washing the waste to neutrality and vacuum drying the resulting deactivated waste; the citric acid solution contains 5 wt.% hydrogen peroxide;
[0088] S2, dispersing 0.59 g of laccase and 0.059 g of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in 2000 g of sodium acetate buffer, wherein the pH of the sodium acetate buffer is 4.5, adding 865 g of deactivated waste to the sodium acetate buffer, adjusting the temperature to 53° C. and shaking for 2.7 hours, adjusting the pH to 7.2 with sodium hydroxide solution, adding 0.17 g of catalase and continuing to shake for 1.7 hours, washing and drying to obtain a detoxified waste, mixing 807 g of the detoxified waste, 200 g of 1-butyl-3-methylimidazole acetate, and 800 g of deionized water, adjusting the temperature to 63° C. and ultrasonically treating for 43 minutes, centrifuging and washing, drying under vacuum at 128° C., and pulverizing to obtain a detoxified waste; the laccase activity is ≥15 U / mg, and the catalase activity is ≥5000 U / mg;
[0089] S3, mixing 100 g of chitosan solution with 1.8 g of polyethyleneimine, wherein the mass ratio of chitosan, glacial acetic acid, and deionized water in the chitosan solution is 2:1:97, adjusting the temperature to 43°C and stirring for 1.7 hours to obtain a chitosan solution-polyethyleneimine mixture, then adding 1 g of the chitosan solution-polyethyleneimine mixture to 1 g of a 2 wt.% sodium tripolyphosphate solution, allowing to stand for 1.6 hours, then centrifuging and freeze-drying to obtain polyethyleneimine-chitosan microspheres;
[0090] S4, 565g of detoxified waste, 31g of polyethyleneimine-chitosan microspheres, 75g of modified carboxylated cellulose and 19g of modified PEEK are mixed evenly, and then 385g of new melamine resin and 25g of castor oil are added, mixed evenly and vacuum degassed to obtain a slurry, wherein the new melamine resin is a water-soluble melamine resin with a solid content of 40%, and the technical indicators of the water-soluble melamine resin comply with GB4806.7-2016; the slurry is injected into the mold cavity and a pressing process is performed, wherein the upper mold temperature of the pressing process is 164°C, and the lower mold temperature is 301°C. The pressure is first increased to 5MPa and maintained for 3min, and then pressurized to 15MPa and maintained for 10min to obtain a composite material prepared using melamine waste.
[0091] Comparative Example 1
[0092] This comparative example provides a composite material prepared using melamine waste and a preparation method thereof. The difference between this comparative example and Example 1 is that the treatment of the melamine waste in step S1 is omitted, and the melamine waste is directly treated in step S2. Other process parameters and operating conditions are exactly the same as those in Example 1.
[0093] Comparative Example 2
[0094] This comparative example provides a composite material prepared using melamine waste and a preparation method thereof. The difference between it and Example 1 is that the treatment of the deactivated waste in step S2 is omitted, and the detoxified waste in step S4 is replaced with an equal mass of deactivated waste. The other process parameters and operating conditions are exactly the same as those in Example 1.
[0095] Comparative Example 3
[0096] This comparative example provides a composite material prepared using melamine waste and a preparation method thereof. The difference between this comparative example and Example 1 is that the mass of the polyethyleneimine-chitosan microspheres in S4 is 0, and the other process parameters and operating conditions are exactly the same as those in Example 1.
[0097] The free formaldehyde test method for the composite materials prepared in Examples 1-4 and Comparative Examples 1-3 was in accordance with GB 31604.48-2016. The test results are shown in Table 1.
[0098] Table 1 Test results of composite materials prepared from melamine waste in Examples 1-4 and Comparative Examples 1-3
[0099]
[0100] As can be seen from Table 1, compared with Example 1, the free formaldehyde content of Comparative Examples 1-3 is increased. In Comparative Example 1, step S1 is omitted, and the cross-linked network of the melamine waste is not physically destroyed. The subsequent steps fail because they cannot contact the internal bound formaldehyde, resulting in a large amount of encapsulated formaldehyde remaining in the composite material. In Comparative Example 2, step S2 is omitted. The lack of the laccase-mediator system causes the bound formaldehyde to be unable to be converted into a free state. The subsequent adsorption step can only capture surface free formaldehyde and is ineffective for internal formaldehyde. The mass of the polyethyleneimine-chitosan microspheres in Comparative Example 3 is 0. The lack of microspheres causes the composite material to lose its chemical adsorption capacity, and free formaldehyde can quickly diffuse to the material surface through interface defects.
[0101] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for preparing a composite material using melamine waste, characterized in that: The preparation method comprises: S1, placing the melamine waste in a steam explosion tank and then releasing the pressure to normal pressure instantly, and immediately immersing the waste in a citric acid solution after the explosion to obtain a deactivated waste; S2, dispersing laccase and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt in sodium acetate buffer, adding the deactivated waste to the sodium acetate buffer, and then adding catalase to obtain a deactivated waste, and mixing the deactivated waste, 1-butyl-3-methylimidazolium acetate, and deionized water to obtain a detoxified waste; S3, mixing the chitosan solution and polyethyleneimine to obtain a chitosan solution-polyethyleneimine mixture, then adding the chitosan solution-polyethyleneimine mixture to a sodium tripolyphosphate solution, allowing the mixture to stand and freeze-drying to obtain polyethyleneimine-chitosan microspheres; S4, uniformly mixing the detoxified waste, polyethyleneimine-chitosan microspheres, modified carboxylated cellulose and modified PEEK, then adding new melamine resin and castor oil to obtain a slurry, injecting the slurry into a mold cavity and performing a pressing process to obtain a composite material prepared using melamine waste.
2. The method for preparing a composite material using melamine waste according to claim 1, characterized in that: The preparation method of the modified carboxylated cellulose comprises: A1, γ-glycidyloxypropyltrimethoxysilane, ethanol aqueous solution and triethylamine are mixed and stirred, and then carboxylated cellulose is added and refluxed to obtain modified carboxylated cellulose.
3. The method for preparing a composite material using melamine waste according to claim 1, characterized in that: The preparation method of the modified PEEK comprises: A2: PEEK powder is mixed with concentrated sulfuric acid to obtain acid-etched PEEK, which is then dispersed in KH550 ethanol solution and solidified after ultrasonic treatment to obtain modified PEEK.
4. The method for preparing a composite material using melamine waste according to claim 1, characterized in that: In S1: The steam explosion tank is set at a pressure of 1.8-2.0 MPa and a temperature of 200-210°C. The concentration of the citric acid solution is 0.1 M, and contains 5 wt.% of hydrogen peroxide.
5. The method for preparing a composite material using melamine waste according to claim 1, characterized in that: In S2: The mass ratio of the laccase, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, sodium acetate buffer, deactivated waste and catalase is (0.57-0.6):(0.054-0.06):2000:(860-880):(0.17-0.19); The activity of the laccase is ≥15 U / mg; The pH of the sodium acetate buffer is 4.5; The activity of the catalase is ≥5000 U / mg; The mass ratio of the jointly treated waste, 1-butyl-3-methylimidazolium acetate and deionized water is (800-810):200:
800.
6. The method for preparing a composite material using melamine waste according to claim 1, characterized in that: In S3: The mass ratio of chitosan, glacial acetic acid and deionized water in the chitosan solution is 2:1:97; The mass ratio of the chitosan solution to polyethyleneimine is 100:(1-2); The mass ratio of the chitosan solution-polyethyleneimine mixed solution to the sodium tripolyphosphate solution is 1:
1.
7. The method for preparing a composite material using melamine waste according to claim 1, characterized in that: In S4: The mass ratio of the detoxified waste, polyethyleneimine-chitosan microspheres, modified carboxylated cellulose, modified PEEK, new melamine resin and castor oil is (550-570): (30-35): (70-78): (15-20): (380-400): (20-30); The new melamine resin is a water-soluble melamine resin with a solid content of 40%. The technical indicators of the water-soluble melamine resin comply with GB4806.7-2016; The upper mold temperature of the pressing process is 160-165°C, the lower mold temperature is 300-305°C, and the pressure is first increased to 5MPa and maintained for 3 minutes, and then increased to 15MPa and maintained for 10 minutes.
8. The method for preparing a composite material using melamine waste according to claim 2, characterized in that: In A1: The mass ratio of the gamma-glycidyloxypropyltrimethoxysilane, the ethanol aqueous solution, triethylamine and the carboxylated cellulose is 30:970:5:(10-13).
9. The method for preparing a composite material using melamine waste according to claim 3, characterized in that: In A2: The mass ratio of the PEEK powder to concentrated sulfuric acid is 1:10; The mass ratio of the acid-etched PEEK to the KH550 ethanol solution is 1:
20.
10. A composite material prepared from melamine waste, characterized in that: Obtained according to the preparation method according to any one of claims 1 to 9.