Metal-based ionic liquid compound flame retardant and method for preparing flame-retardant wood by using same

Abstract

The invention belongs to the technical field of wood flame-retardant modification, and particularly relates to a metal-based ionic liquid compound flame retardant and a method for preparing flame-retardant wood by using the same. The preparation method comprises the following steps: putting 1-methylimidazole and tributyl phosphate into a reaction container, heating, condensing and refluxing to obtain an ionic liquid flame retardant containing 1-butyl-3-methylimidazole dibutyl phosphate; wood is sequentially soaked in a solution containing trivalent metal ions and an ionic liquid flame retardant, the metal ionic liquid flame retardant is generated in gaps of the wood in situ, and the smoke abatement type flame retardant modified wood can be prepared through drying in the shade, drying and water balance. The imidazolium ionic liquid and the metal trivalent ions are subjected to complexation reaction in the wood to form the metal type ionic liquid flame retardant, the purposes of smoke abatement, flame retardance, loss resistance and the like are achieved, and the application of the wood flame retardant technology and flame retardant wood products is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of wood flame retardant modification, and particularly relates to a metal-based ionic liquid compound flame retardant and a method for preparing flame retardant wood by using the same. Background Art

[0002] As one of the four major basic building materials, wood is widely used in the fields of building construction and furniture manufacturing due to its natural texture and aesthetic value. This renewable and environmentally friendly material has the non-toxic characteristic and has unique advantages in sustainable utilization. However, in practical applications, the natural flammable property of wood makes it extremely easy to become an energy release source in building fires, and the high heat load and dense soot generated during the combustion process seriously threaten the safety of personnel and property, which determines the necessity of flame retardant modification treatment for it.

[0003] Divided from the molecular structure dimension, wood flame retardants can be classified into two major systems: organic and inorganic. Organic flame retardants cover categories such as resin type, reactive type, and nitrogen-phosphorus compounds, etc., but their pyrolysis process is often accompanied by the generation of toxic substances, and there are limitations such as complex processes and high application costs. In contrast, the inorganic flame retardant system is more in line with the concept of green environmental protection development. Among them, silicon-based and boron-based flame retardants have attracted much attention due to the characteristics of easy availability of raw materials and environmental friendliness. Taking boric acid as an example, this material has the advantages of non-toxicity, high permeability, and maintaining the intrinsic properties of wood, but the flame retardant efficiency of using the monomer alone is limited. As a typical silicon compound, silicate can effectively fill the micro-pores of wood with its low viscosity and nano-scale particle size, and its thermal stability and biological safety are particularly prominent. However, flame retardants represented by sodium silicate have the defect of fixation, and are prone to leaching phenomenon in a humid environment, which not only leads to the attenuation of flame retardant performance, but also causes surface pollution of wood and secondary environmental problems.

[0004] In view of this, the inventor expects to provide a metal-based ionic liquid compound flame retardant, which can achieve the purpose of "multiple effects with one agent" such as smoke elimination, flame retardancy, and anti-leaching when preparing flame retardant wood, and expand the application of wood flame retardant technology and flame retardant wood products. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems existing in the traditional technology, and provide a metal-based ionic liquid compound flame retardant and a method for preparing flame retardant wood by using the same.

[0006] To achieve the above technical purpose and reach the above technical effect, the present invention is realized through the following technical solutions:

[0007] A smoke-eliminating metal-based ionic liquid compound flame retardant, comprising component A and component B;

[0008] Component A is an ionic liquid impregnating solution of 1-butyl-3-methylimidazolium dibutyl phosphate;

[0009] Component B is a solution containing trivalent metal ions;

[0010] The molar ratio of 1-butyl-3-methylimidazolium dibutyl phosphate in Component A to the trivalent metal ions in Component B is 0.05 to 1.5:1;

[0011] Component A and Component B maintain chemical inertness during independent storage and only form a composition with a synergistic flame retardant effect after mixing.

[0012] Furthermore, in the above-mentioned compound flame retardant, the preparation of Component A includes the following steps:

[0013] 1) Add equimolar amounts of 1-methylimidazole and tributyl phosphate to a round-bottom flask and react at a constant temperature under an oil bath condition;

[0014] 2) After the reaction is completed, wait for the reaction system to cool naturally to room temperature to obtain a product in the form of a light brown transparent liquid;

[0015] 3) Add ether and the product to a separatory funnel in sequence, slowly shake to make the two phases fully contact and mix; after standing and separating for 4 - 6 minutes, collect the lower ionic liquid phase; repeat the above purification process 2 - 4 times to remove impurities of 1-methylimidazole and tributyl phosphate to obtain purified liquid I;

[0016] 4) Place the purified liquid I in a vacuum drying oven to dry and remove the residual trace ether solvent to obtain liquid II;

[0017] 5) Add deionized water to liquid II to obtain Component A.

[0018] Furthermore, in the above-mentioned compound flame retardant, in step 1), react at a constant temperature for 8 - 12 hours under an oil bath condition of 140 - 160 °C.

[0019] Furthermore, in the above-mentioned compound flame retardant, in step 4), place it in a vacuum drying oven at 35 - 45 °C to dry for 8 - 16 hours.

[0020] Furthermore, in the above-mentioned compound flame retardant, in step 5), the volume ratio of liquid II to deionized water is 0.01 - 15:100.

[0021] Furthermore, in the above-mentioned compound flame retardant, the trivalent metal ions in Component B are Fe 3+ or Al 3+ .

[0022] Furthermore, in the above-mentioned compound flame retardant, the concentration of the trivalent metal ions in Component B is 0.05 - 1.5 mol / / L.

[0023] The present invention also provides a method for preparing flame-retardant wood using the above-mentioned compound flame retardant, including the following steps:

[0024] S1. Place the dried raw wood into component B and impregnate it under negative pressure at normal temperature and -0.01 to -0.1 MPa for 20 to 40 minutes;

[0025] S2. Take out the impregnated wood obtained in step S1, wipe off the excess liquid on the surface, and dry it in an oven at 60 °C for 6 to 18 hours;

[0026] S3. Place the dried wood obtained in step S2 into component A and impregnate it under negative pressure at normal temperature and -0.01 to -0.1 MPa for 40 to 80 minutes;

[0027] S4. Take out the impregnated wood obtained in step S3, wipe off the excess liquid on the surface, and dry it in an oven at 60 °C for 6 to 18 hours;

[0028] S5. Place the dried wood obtained in step S4 into a constant temperature and humidity chamber and condition it to moisture equilibrium at 10 to 30 °C and 60 to 70 rh%, to obtain flame-retardant wood modified with metal-based ionic liquid flame retardant.

[0029] Furthermore, in step S1, the raw wood is poplar, eucalyptus, paulownia, ash, radiata pine, larch, masson pine or Chinese fir.

[0030] The present invention also provides a flame-retardant wood prepared by the above method.

[0031] The beneficial effects of the present invention are:

[0032] 1. The pyrolysis temperature of the metal ionic liquid flame retardant IL Al and IL Fe of the present invention is 265 to 340 °C, and the char residue amounts at 700 °C reach 30.92% and 39.39%, which are 3.88 and 4.95 times that of ionic liquid flame retardant A (i.e., component A). Through infrared spectrum analysis, it can be seen that trivalent metal ions (Al 3+ , Fe 3+ ) interact with ionic liquid flame retardant A by coordinating with phosphate ester groups, and the metal ionic liquid flame retardant fills the wood voids in the form of a non-water-soluble complex.

[0033] 2. The metal ionic liquid flame-retardant modified wood (IL Al W and IL FeThe moisture absorption rate of (W) is significantly reduced, and the anti-leaching rate of the flame retardant is significantly increased. The moisture absorption rates of the wood specimens in Examples 1-2 were reduced by 49.23% and 35.02% respectively compared with Comparative Example 2, and the anti-leaching rates of the flame retardant were increased by 916.67% and 1064.20% respectively compared with the ionic liquid flame retardant A. This is mainly because the metal ionic liquid is in-situ generated on the surface and cell pores of the wood, reducing the contact of the wood with moisture and hindering the leaching of the flame retardant.

[0034] 3. The metal-based ionic liquid flame retardant can catalyze the release of H2O from wood at low temperatures, reduce the temperature of the combustion system and the concentration of combustible gas products, and promote the formation of a dense and stable carbon layer on the wood surface, thereby reducing the heat and smoke release. The metal-based ionic liquid flame retardant modified wood (IL Al W and IL Fe W) are both flame-retardant and smoke-suppressing materials.

[0035] 4. The wood modified with the metal ionic liquid flame retardant was not ignited under the condition of 10s open flame ignition in the UL-94 test; the LOI value of the specimen was between 29% and 31%. The THR of the wood modified with the metal ionic liquid flame retardant (IL Al W and IL Fe W) was reduced by 22.95% and 24.20% respectively compared with the untreated wood, and the TSP was reduced by 70.74% and 68.84% respectively compared with the specimen modified with the ionic liquid flame retardant A.

[0036] 5. The amount of toxic gas released during the combustion of the wood modified with the metal ionic liquid flame retardant of the present invention is extremely low. The carbon monoxide gas release amounts during the combustion of Examples 1-4 were only 6.1%, 4.5%, 5.3%, and 3.6% of the wood in Comparative Example 1.

[0037] Of course, it is not necessary for any product implementing the present invention to achieve all of the above advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 is the TG curve of each flame retardant;

[0040] Figure 2 is the infrared spectrum of each flame retardant;

[0041] Figure 3 is IL Al W and ILFe TG curve of W

[0042] Figure 4 is IL Al W and IL Fe Heat release rate (HRR) graph of W

[0043] Figure 5 is IL Al W and IL Fe Fire growth index (FGI) graph of W

[0044] Figure 6 is IL Al W and IL Fe Total heat release (THR) graph of W

[0045] Figure 7 is IL Al W and IL Fe Total smoke production (TSP) graph of W

[0046] Figure 8 is IL Al W and IL Fe Smoke production rate (SPR) graph of W

[0047] Figure 9 is IL Al W and IL Fe Moisture absorption rate graph of W

[0048] Figure 10 is IL Al W and IL Fe Leaching resistance rate graph of flame retardant in W Specific implementation mode

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0050] A smoke-suppressing metal-based ionic liquid compound flame retardant includes component A and component B;

[0051] Component A is an ionic liquid impregnation solution of 1-butyl-3-methylimidazolium dibutyl phosphate;

[0052] Component B is a solution containing trivalent metal ions; the trivalent metal ions are Fe 3+ or Al 3+ . The concentration of trivalent metal ions in component B is 0.05 - 1.5 mol / / L.

[0053] Component A and component B maintain chemical inertness when stored independently and only form a composition with a synergistic flame retardant effect after mixing.

[0054] In the present invention, the preparation of component A includes the following steps:

[0055] 1) Add equimolar amounts of 1-methylimidazole and tributyl phosphate to a round-bottom flask and react at a constant temperature of 140 - 160 °C in an oil bath for 8 - 12 h;

[0056] 2) After the reaction is completed, allow the reaction system to cool naturally to room temperature to obtain a product in the form of a light brown transparent liquid;

[0057] 3) Add diethyl ether and the product to a separatory funnel in sequence, slowly shake to allow the two phases to come into full contact and mix; after standing and separating for 4 - 6 min, collect the lower ionic liquid phase; repeat the above purification process 2 - 4 times to remove impurities of 1-methylimidazole and tributyl phosphate to obtain purified liquid I;

[0058] 4) Place the purified liquid I in a vacuum drying oven at 35 - 45 °C and dry for 8 - 16 h to remove the residual trace diethyl ether solvent to obtain liquid II;

[0059] 5) Add deionized water to liquid II, and the volume ratio of liquid II to deionized water is 0.01 - 15:100 to obtain component A.

[0060] The method for preparing flame-retardant wood using the above compound flame retardant includes the following steps:

[0061] S1. Place the dried raw wood into component B and impregnate it under negative pressure at normal temperature and -0.01 to -0.1 MPa for 20 - 40 min; the raw wood is poplar, eucalyptus, paulownia, ash, radiata pine, larch, masson pine or Chinese fir.

[0062] S2. Take out the impregnated wood obtained in step S1, wipe off the excess liquid on the surface, and dry it in an oven at 60 °C for 6 - 18 h.

[0063] S3. Place the dried wood obtained in step S2 into component A and impregnate it under negative pressure at normal temperature and -0.01 to -0.1 MPa for 40 - 80 min.

[0064] S4. Take out the impregnated wood obtained in step S3, wipe off the excess liquid on the surface, and dry it in an oven at 60 °C for 6 - 18 h.

[0065] S5. Put the dried wood obtained in step S4 into a thermostatic and humidistatic chamber, and condition it to reach moisture equilibrium at 10 - 30°C and 60 - 70% rh to obtain the flame-retardant wood modified with metal-based ionic liquid flame retardant.

[0066] The relevant specific examples and comparative examples of the present invention are as follows:

[0067] Poplar wood was selected as the original wood, and the relevant definitions are described as follows:

[0068] Poplar wood material: Boards with dimensions of 20 mm (radial) × 100 mm (tangential) × 100 mm (longitudinal) were cut from the sapwood part above breast height of poplar trees and were untreated.

[0069] Pre-treated poplar wood: Boards with dimensions of 20 mm (radial) × 100 mm (tangential) × 100 mm (longitudinal) were cut from the sapwood part above breast height of poplar trees, air-dried in the atmosphere until the moisture content ≤ 50%, and then the boards were placed in a blast drying equipment and dried at 30°C until the moisture content ≤ 15%.

[0070] Example 1

[0071] This example provides a flame-retardant wood, which is prepared using a compound flame retardant, denoted as IL Al W. The specific preparation method of the metal ionic liquid-modified poplar wood includes the following steps:

[0072] S1. Place the dried original wood into component B, and impregnate it under negative pressure at normal temperature and -0.05 MPa for 30 min; the original wood is pre-treated poplar wood. Among them, the solid-liquid ratio of the original wood to the component B solution is 1:10.

[0073] S2. Take out the impregnated wood obtained in step S1, wipe off the excess liquid on the surface, and dry it in an oven at 60°C for 12 h.

[0074] S3. Place the dried wood obtained in step S2 into component A, and impregnate it under negative pressure at normal temperature and -0.05 MPa for 60 min. Among them, the solid-liquid ratio of the dried wood to the component A solution is 1:10.

[0075] S4. Take out the impregnated wood obtained in step S3, wipe off the excess liquid on the surface, and dry it in an oven at 60°C for 12 h.

[0076] S5. Put the dried wood obtained in step S4 into a thermostatic and humidistatic chamber, and condition it to reach moisture equilibrium at 20°C and 65% rh for 7 days to obtain the flame-retardant wood modified with metal-based ionic liquid flame retardant.

[0077] In this example, component A is an ionic liquid impregnation solution of 1-butyl-3-methylimidazolium dibutyl phosphate. The preparation of component A includes the following steps:

[0078] 1) Add equimolar amounts of 1-methylimidazole and tributyl phosphate to a round-bottom flask and react at a constant temperature of 150 °C in an oil bath for 10 h;

[0079] 2) After the reaction is completed, allow the reaction system to cool naturally to room temperature to obtain a product that is a light brown transparent liquid;

[0080] 3) Add ether and the product to a separatory funnel in sequence, slowly shake to allow the two phases to come into full contact and mix; after standing and separating for 5 min, collect the lower ionic liquid phase; repeat the above purification process 3 times to remove 1-methylimidazole and tributyl phosphate impurities to obtain purified liquid I;

[0081] 4) Place the purified liquid I in a vacuum drying oven at 40 °C and dry for 12 h to remove the residual trace ether solvent to obtain liquid II;

[0082] 5) Add deionized water to liquid II, and the volume ratio of liquid II to deionized water is 1:100 to obtain component A.

[0083] 1 In this example, component B is an aqueous solution of 0.5 mol / L Al2(SO4)3·18H2O.

[0084] Example 2

[0085] This example provides a flame-retardant wood, which is prepared using a compound flame retardant, denoted as IL Fe W. The specific preparation method is basically the same as that of Example 1, except that component B is an aqueous solution of 0.5 mol / L Fe2(SO4)3.

[0086] Example 3

[0087] This example provides a flame-retardant wood, which is prepared using a compound flame retardant, denoted as IL Al- 0.25W. The specific preparation method is basically the same as that of Example 1, except that component B is an aqueous solution of 0.25 mol / L Al2(SO4)3·18H2O.

[0088] Example 4

[0089] This example provides a flame-retardant wood, which is prepared using a compound flame retardant, denoted as IL Fe- 0.25W. The specific preparation method is basically the same as that of Example 1, except that component B is an aqueous solution of 0.25 mol / L Fe2(SO4)3.

[0090] Comparative Example 1

[0091] In this comparative example, poplar wood material is selected, denoted as Ctrl.

[0092] Comparative Example 2

[0093] This comparative example provides a flame-retardant wood, denoted as ILW. The preparation process is as follows: Select pretreated wood, place the pretreated wood in Component A of Example 1, and perform negative-pressure impregnation at room temperature and -0.05 Mpa for 2 h; take out the wood and air-dry it for 3 h, then dry it at 40 °C, and then put it into a constant temperature and humidity chamber to adjust the moisture balance for 7 days at 20 °C and 65% rh to obtain the flame-retardant wood.

[0094] Examples of compound flame retardants

[0095] Preparation of Component A:

[0096] Add equimolar amounts of 1-methylimidazole and tributyl phosphate to a round-bottom flask, and carry out a constant-temperature reaction at 150 °C in an oil bath for 10 h. After the reaction is completed, wait for the reaction system to cool naturally to room temperature to obtain a light brown transparent liquid. Add ether and the product to a separatory funnel in sequence, and slowly shake to make the two phases fully contact and mix. After standing and separating for 5 min, collect the lower ionic liquid phase. Repeat the above purification process 3 times to remove impurities such as 1-methylimidazole and tributyl phosphate. Finally, place the purified ionic liquid flame retardant in a vacuum drying oven at 40 °C and dry it for 12 h to remove the residual trace ether solvent. Dissolve the remaining liquid in deionized water according to a volume concentration of 0.5 - 10:100 to obtain Component A (denoted as IL DP ).

[0097] The reaction equation in Component A is as follows:

[0098]

[0099] Preparation of compound flame retardant

[0100] Add Component A to a 50 mL beaker, respectively prepare 0.5 mol / L aqueous solutions of Fe2(SO4)3 and Al2(SO4)3·18H2O, and add the above metal salt solutions to the ionic liquid flame retardant through a constant-pressure separatory funnel for complexation reaction. After the reaction is completed, transfer the mixed solution to a centrifuge tube, centrifuge at 8000 rpm for 5 min to obtain a precipitate, wash it 3 times with deionized water, and then place the product in a vacuum drying oven and dry it at 60 °C for 12 h to finally obtain a white powder product (IL Al ) and a yellow powder product (IL Fe ).

[0101] IL DP , IL Al , and IL Fe The thermal decomposition parameters are shown in Table 1:

[0102] Table 1

[0103]

[0104] Note: T1, T2, and T3 are temperature ranges at different stages, with the unit of °C; ML is the weight loss rate, with the unit of %.

[0105] IL DP 、IL Al and IL Fe 's TG curves are as shown in Figure 1 IL DP 、IL Al and IL Fe 's infrared spectra are as shown in Figure 2 shown.

[0106] Compared with ionic liquid flame retardant A (i.e., component A), the metal ionic liquid flame retardant IL of the present invention Al 、IL Fe has improved thermal stability, and the char residue amounts at 700 °C are increased by 30.92% and 39.39% respectively compared with flame retardant A. Through infrared spectrum analysis, it can be known that the metal ions (Al 3+ 、Fe 3+ ) in the metal ionic liquid flame retardant form complexes through coordination interactions with phosphate ester groups.

[0107] The TG curves of the wood in Comparative Examples 1-2 and Examples 1-2 are as shown in Figure 3 shown. From thermogravimetric analysis, it can be known that the pyrolysis temperature of the metal ionic liquid flame retardant modified wood is 30 °C earlier than that of the untreated wood, and the char residue amounts at 700 °C are 25.04% and 34.58% respectively, which are increased by 67.57% and 132.00% respectively compared with the wood in Comparative Example 1. The metal ionic liquid flame retardants IL Al and IL Fe can promote the release of water vapor by the modified wood in the early stage of combustion, reduce the system temperature and the concentration of combustible gases; at the same time, the flame retardant can also inhibit the release of combustible gases by the modified wood and generate gaseous phosphorus-containing compounds to capture active H· and OH· free radicals in the flame zone.

[0108] The drug loading rates, LOI values, and flame extinction time values in the vertical burning test of Examples 1-2 and Comparative Examples 1-4 are shown in Table 2:

[0109] Table 2

[0110]

[0111] Among them, the drug loading rate (WPG, %) of the wood specimen is calculated according to the formula:

[0112]

[0113] Put the wood specimens of the required size for the experiment into the drying oven and dry them to absolute dryness, and record the mass as m0. After being treated by the flame retardant modification method, the mass of the wood specimens is recorded as m1.

[0114] The LOI value of the untreated specimens in Comparative Example 1 was 18%, and it was easily ignited under air conditions; the LOI value of Comparative Example 2 was 25%, and it was ignited after being placed in the flame for 10 s under air conditions and continued to burn for 71 s before extinguishing. Therefore, there are relatively large fire hazards in the wood of the comparative examples.

[0115] The LOI values of the metal ionic liquid flame retardant modified woods in Examples 1 to 4 were all greater than 27%, between 29% and 31%, belonging to non-combustible materials. The samples of Examples 1 to 4 were not ignited after being placed in the flame for 10 s under air conditions. Therefore, the fire safety of the flame retardant wood of the present invention has been significantly improved.

[0116] The heat release and toxic smoke release performance parameters of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 3:

[0117] Table 3

[0118]

[0119] The heat release rate curves of Examples 1 to 2 and Comparative Examples 1 to 2 are as Figure 4 shown, the fire growth index is as Figure 5 shown, the total heat release amount curve is as Figure 6 shown, the total smoke release amount is as Figure 7 shown, the smoke release rate is as Figure 8 shown, the moisture absorption rate is as Figure 9 shown, and the anti-loss rate is as Figure 10 shown.

[0120] The second heat release peak PHRR2 of the woods in Comparative Examples 1 and 2 were 332.27 and 280.67 kW·m -2 , respectively, and the second heat release peak time TPHRR2 were 382 and 324 s, respectively. The woods in Comparative Examples 1 and 2 reached the maximum heat release value in a relatively short time, and the fire growth indexes were 0.87 and 0.85 m 2 ·s·kW -1 , indicating that there are relatively large fire safety hazards in the woods of Comparative Examples 1 and 2. The second heat release peak PHRR2 of the woods in Examples 1 to 4 decreased to 172.08 - 135.28 kW·m -2 , the heat release peak time TPHRR2 was postponed to 372 - 500 s, and the fire growth index decreased to 0.28 - 0.46 m 2 ·s·kW -1 . Therefore, the fire safety of Examples 1 to 4 has been significantly improved.

[0121] It can also be seen from the total heat release and total smoke release that the overall flame retardancy and smoke suppression performance of Examples 1-4 are significantly improved: the THR of the specimens in Examples 1-2 decreased by 22.95% and 24.20% respectively compared with that of Comparative Example 1, and the TSP decreased by 70.74% and 68.84% compared with that of Comparative Example 2. In particular, the release amount of toxic gases during the combustion of Examples 1-4 decreased, only being 6.1%, 4.5%, 5.3%, and 3.6% of the carbon monoxide release amount during the combustion of the wood in Comparative Example 1. The reduction in the release amount of toxic gases, especially carbon monoxide, plays an important role in reducing the fire risk and threatening the life and health of people.

[0122] The metal-based ionic liquid flame retardant can catalyze the release of H2O from wood at low temperature, reduce the temperature of the combustion system and the concentration of combustible gas products, and promote the formation of a dense and stable carbon layer on the wood surface, thereby reducing the heat and smoke release amounts. The metal ionic liquid flame retardant (IL Al 、IL Fe ) exerts flame retardancy and smoke suppression effects on wood through the condensed phase and the gas phase together.

[0123] Through the "two-step impregnation method", metal ions Al 3+ 、Fe 3+ can be introduced into the ionic liquid flame retardant A, and the metal ionic liquid flame retardants IL Al and IL Fe are in-situ synthesized in the wood. The metal ionic liquid flame retardant is filled in the wood pores in the form of a water-insoluble porous complex. The moisture absorption rates of the wood specimens in Examples 1-2 decreased by 49.23% and 35.02% respectively compared with that of Comparative Example 2, and the anti-leaching rates of the metal ionic liquid flame retardants IL Al and IL Fe increased by 916.67% and 1064.20% respectively compared with that of the ionic liquid flame retardant A.

[0124] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to only the specific embodiments. Obviously, many modifications and changes can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A smoke-suppressing metal-based ionic liquid composite flame retardant, characterized in that: Comprising component A and component B; Component A is an ionic liquid impregnation solution of 1-butyl-3-methylimidazole dibutyl phosphate; Component B is a solution containing trivalent metal ions; The molar ratio of 1-butyl-3-methylimidazole dibutyl phosphate in component A to the trivalent metal ion in component B is 0.05-1.5:1; Component A and component B remain chemically inert when stored independently, and only form a composition with a synergistic flame retardant effect after mixing.

2. The compound flame retardant according to claim 1, characterized in that: The preparation of component A comprises the following steps: 1) Add 1-methylimidazole and tributyl phosphate in an equal molar ratio into a round-bottom flask and react at a constant temperature under oil bath conditions; 2) After the reaction is completed, the reaction system is cooled naturally to room temperature to obtain a product in the form of a light brown transparent liquid; 3) Add ether and the product to a separatory funnel in sequence, and shake slowly to allow the two phases to fully contact and mix; after standing for 4 to 6 minutes to separate the layers, collect the lower ionic liquid phase; repeat the above purification process 2 to 4 times to remove 1-methylimidazole and tributyl phosphate impurities, and obtain a purified liquid I; 4) drying the purified liquid I in a vacuum drying oven to remove the residual trace ether solvent to obtain liquid II; 5) Deionized water is added to liquid II to obtain component A.

3. The compound flame retardant according to claim 2, characterized in that: In step 1), the reaction is carried out at a constant temperature of 140 to 160° C. in an oil bath for 8 to 12 hours.

4. The composite flame retardant according to claim 2, characterized in that: In step 4), place in a vacuum drying oven at 35-45° C. and dry for 8-16 hours.

5. The compound flame retardant according to claim 2, characterized in that: In step 5), the volume ratio of liquid II to deionized water is 0.5-10:

100.

6. The compound flame retardant according to claim 1, characterized in that: The trivalent metal ion in component B is Fe 3+ or Al 3+ .

7. The composite flame retardant according to claim 1, characterized in that: The concentration of trivalent metal ions in the component B is 0.05-1.5 mol / / L.

8. A method for preparing flame-retardant wood using the composite flame retardant according to any one of claims 1 to 7, characterized in that: The steps include: S1. Place the dried logs in component B and immerse them in negative pressure at room temperature and -0.01 to -0.1 MPa for 20 to 40 minutes; S2, taking out the impregnated wood obtained in step S1, wiping off excess liquid on the surface, and drying it in an oven at 60° C. for 6 to 18 hours; S3, placing the dried wood obtained in step S2 into component A, and impregnating it under negative pressure at room temperature and -0.01 to -0.1 MPa for 40 to 80 minutes; S4, taking out the impregnated wood obtained in step S3, wiping off excess liquid on the surface, and drying in an oven at 60° C. for 6 to 18 hours; S5, placing the dried wood obtained in step S4 into a constant temperature and humidity chamber, adjusting the humidity balance at 10-30° C. and 60-70 rh%, to obtain flame-retardant wood modified by metal-based ionic liquid flame retardancy.

9. The method according to claim 8, characterized in that In step S1, the raw wood is poplar, eucalyptus, paulownia, ash, radiata pine, larch, masson pine or fir.

10. A flame retardant wood prepared by the method according to claim 8 or 9.

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