Bio-based macromolecular flame retardant, preparation method thereof and flame-retardant nylon material

Abstract

The invention discloses a bio-based macromolecular flame retardant, a preparation method thereof and a flame-retardant nylon material, relates to the technical field of flame-retardant macromolecular materials, and solves the problems of easy migration, poor compatibility and non-sustainability of the existing flame-retardant nylon material. The preparation method comprises the following steps: dissolving aminocaprolactam in a solvent, adding phosphorus-containing micromolecules and an auxiliary agent, fully reacting, evaporating the solvent to dryness, and carrying out post-treatment to obtain a bio-based flame-retardant monomer; the preparation method comprises the following steps: adding a bio-based flame-retardant monomer into a reaction kettle under inert gas, vacuumizing, filling the inert gas, repeating for three times, then adding water to carry out polymerization reaction, and discharging after the polymerization is completed, thereby obtaining the bio-based macromolecular flame retardant. The flame-retardant nylon material comprises the following components in percentage by weight: 70%-99% of nylon resin and 1%-30% of the bio-based macromolecular flame retardant, the nylon resin is aliphatic, aromatic or semi-aromatic nylon resin. The method can be used for preparing flame-retardant nylon products including fabrics, plates, pipes, packages or panels.

Description

Technical Field

[0001] The invention relates to the technical field of flame-retardant polymer materials, and in particular to a bio-based macromolecular flame retardant and a preparation method thereof, and a flame-retardant nylon material. Background Art

[0002] With the application of polymer materials in various electrical, communication, transportation, and fire protection fields, flame retardant polymer materials have attracted more and more attention from researchers. Nylon, as a polymer material with repeating amide groups in the main chain, has developed into one of the world's largest-volume and most widely used engineering plastics with excellent mechanical properties, heat resistance and processability. It is widely used in automobile manufacturing, electronic appliances, textile industry and other fields. However, the limiting oxygen index (LOI) of pure nylon material is only about 24%, and the UL94 flame retardant grade can only reach V-2, which is difficult to meet the stringent requirements for the fire resistance of materials in new energy vehicle interiors, high-end electronic equipment, etc.

[0003] The current mainstream flame retardant modification technology is mainly achieved by adding small molecule flame retardants, such as Chinese patent documents CN119286242A, CN119101352A, and CN116200028A, but these technologies still have significant defects. On the one hand, small molecule flame retardants are easy to precipitate during processing and use, which not only causes the flame retardant performance to decay, but also causes environmental pollution; on the other hand, the flame retardant has a weak interface with the matrix, which seriously damages the mechanical properties of the material. In this regard, Chinese patent document CN104277223A provides a macromolecular flame retardant containing a polysiloxane and a phosphaphenanthrene structure, and polymerizes monomers containing flame retardant functional groups to make macromolecular flame retardants, which can improve the compatibility of flame retardants and polymers, avoid the migration problem of small molecule flame retardants and the loss of mechanical properties of materials, and can be used for halogen-free flame retardant of nylon materials. However, existing macromolecular flame retardants still rely on petroleum-based raw materials, and the high carbon emissions in the production process do not meet the requirements of green development. Summary of the invention

[0004] In order to solve the problems of easy migration, poor compatibility and unsustainability of existing flame-retardant nylon materials, the present invention proposes a bio-based macromolecular flame retardant and a preparation method thereof and a flame-retardant nylon material.

[0005] The technical solution of the present invention is as follows:

[0006] A bio-based macromolecular flame retardant, the structural formula is as follows:

[0007]

[0008] In the formula, R is selected from one of the following structures A to V:

[0009]

[0010] Among them, R1 and R2 are each independently selected from hydrogen, C 1-28 substituted / unsubstituted straight-chain / branched saturated / unsaturated aliphatic hydrocarbon groups, substituted / unsubstituted saturated / unsaturated C 3-15 alicyclic hydrocarbon groups, substituted / unsubstituted C 6-22 aryl groups, substituted / unsubstituted saturated / unsaturated C 7-35 aralkyl groups; wherein the aromatic rings in the aryl group and the aralkyl group have any number of nitrogen atoms as heteroatoms; X1, X2, and X3 are each independently selected from an oxygen atom, a methylene group, and a substituted imino group;

[0011] The substitution means that the group is substituted by one or more substituents, and the substituents are halogen, nitro, hydroxyl, cyano, boric acid group, borate group, C 1-18 straight-chain / branched alkyl groups, C 1-18 straight-chain / branched alkoxy groups, C 1-18 straight-chain / branched alkylamino groups.

[0012] The present invention also provides a preparation method of the above-mentioned bio-based macromolecular flame retardant, which includes the following steps:

[0013] S1. Dissolve aminocaprolactam in a solvent, add a phosphorus-containing small molecule and an auxiliary agent, fully react, evaporate the solvent, and obtain a bio-based flame retardant monomer after post-treatment;

[0014] S2. Under the condition of an inert gas, add the bio-based flame retardant monomer to a reaction kettle, evacuate and then fill with an inert gas and repeat three times, and then add water for a polymerization reaction. After the polymerization is completed, discharge the material to obtain a bio-based macromolecular flame retardant;

[0015] The auxiliary agent is selected from one or more of aldehyde, amine, alcohol, and hydrazine;

[0016] The phosphorus-containing small molecule is selected from one or more of molecules with the following structures:

[0017]

[0018] In the formula, X is a halogen.

[0019] The structural formula of the bio-based flame retardant monomer is as follows:

[0020]

[0021] Preferably, the phosphorus-containing small molecule is selected from one or more of phosphorus trichloride, phosphorus oxychloride, dimethyl chlorophosphate, diethyl chlorophosphate, phenylphosphoryl chloride, dimethylphosphoryl chloride, diethylphosphoryl chloride, diphenylphosphoryl chloride, trimethyl phosphate, triethyl phosphate, dimethyl phenylphosphate, diethyl phenylphosphate, methyl diphenylphosphate, ethyl diphenylphosphate, dimethyl phosphonous chloride, diethyl phosphonous chloride, dibutyl phosphonous chloride, trimethyl phosphite, triethyl phosphite, hexachlorocyclotriphosphazene, and DOPO.

[0022] Preferably, the solvent is selected from one or more of diethyl ether, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, dichloromethane, chloroform, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and water.

[0023] More preferably, the solvent is selected from one or more of tetrahydrofuran, acetonitrile, dichloromethane, ethyl acetate, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0024] Preferably, the reaction time in step S1 is 0.5 h to 24 h, and the reaction temperature is -50°C to 200°C. More preferably, the reaction time in step one is 1 h to 8 h, and the reaction temperature is -20°C to 100°C.

[0025] Preferably, the post-treatment in step S1 is one or more of preparative chromatography, column chromatography, sublimation purification, and recrystallization; the solvent used for recrystallization is a mixture of one or more of petroleum ether, methanol, ethanol, propanol, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethyl acetate, isoamyl acetate, acetonitrile, methyl ethyl ketone, acetone, dichloromethane, chloroform, carbon tetrachloride, N,N-dimethylformamide, pyridine, dimethyl sulfoxide, and water. More preferably, the post-treatment method is recrystallization using one solvent selected from petroleum ether, diethyl ether, ethyl acetate, acetone, dichloromethane, and tetrahydrofuran.

[0026] Preferably, a catalyst is further added before vacuum pumping in step S2; the catalyst is selected from one or more of hydrides / oxyacids of halogens, sulfur, nitrogen / phosphorus oxyacids, C 1-35 1-5 yuan carboxylic acids / hydroxy acids / amino acids / sulfonic acids / phosphoric acids of, hydroxides, carbonates, bicarbonates, and basic carbonates of alkali metals / alkaline earth metals; more preferably, the catalyst is selected from one or more of hydrochloric acid, sulfuric acid, adipic acid, 6-aminocaproic acid, phosphoric acid, sodium hydroxide, calcium hydroxide, and potassium carbonate. The molar ratio of the catalyst to the bio-based flame retardant monomer is 0.001 to 0.1:1.

[0027] Preferably, the mass ratio of the bio-based flame retardant monomer to water in step S2 is 10-200:1. More preferably, the mass ratio of the bio-based flame retardant monomer to water is 20-100:1.

[0028] Preferably, the conditions for the polymerization reaction in step S2 are as follows:

[0029] The polymerization temperature is 140°C to 320°C; the polymerization time is 2 h to 96 h; the polymerization pressure is -0.1 MPa to 5 MPa.

[0030] The present invention also provides a flame-retardant nylon material, comprising the following components by weight percentage:

[0031] 70%-99% of nylon resin and 1%-30% of the above bio-based macromolecular flame retardant;

[0032] The nylon resin is an aliphatic, aromatic or semi-aromatic nylon resin.

[0033] More preferably, the nylon resin is one of nylon 6, nylon 66, nylon 610, nylon 56, nylon 11, nylon 12, and nylon 6T.

[0034] The present invention can be applied to the preparation of flame-retardant nylon products, and the flame-retardant nylon products are selected from fabrics, sheets, pipes, packaging, or panels.

[0035] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0036] The present invention uses amino-caprolactam derived from lysine as a raw material, reacts with a phosphorus-containing small molecule to obtain a bio-based flame retardant monomer; then ring-opening polymerizes the bio-based flame retardant monomer to obtain a bio-based macromolecular flame retardant. The bio-based macromolecular flame retardant can be blended with other nylon materials to obtain a flame-retardant nylon material. Compared with the prior art, the bio-based macromolecular flame retardant provided by the present invention has better sustainability; the used flame retardant with a polyamide macromolecular structure has better compatibility with the nylon substrate, and no additional compatibilizer is required during the blending process, and it has better anti-migration and durability. Moreover, the mechanical properties of the obtained flame-retardant nylon are not much different from those of the raw materials, and the flame retardant performance is excellent.

[0037] Through precise molecular design, the present invention realizes the synergistic optimization in three dimensions of flame retardancy efficiency, mechanical property retention rate, and environmental friendliness, solves the long-existing "performance-environmental protection" trade-off problem in the field of flame retardancy, and is suitable for large-scale production. It can be processed and formed by processes such as injection molding, blow molding, extrusion molding, and spinning, and has wide applications in fields such as fabrics, sheets, pipes, packaging, and various panels that require flame retardancy. Detailed implementation manners

[0038] To make the technical solution of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be construed as a limitation of the present invention.

[0039] Any specific numerical value (including the endpoints of a numerical range) disclosed herein is not limited to the exact value of that numerical value, but should be understood to also cover values close to that exact value, for example, all possible numerical values within ±5% of that exact value. And, for the disclosed numerical ranges, any combination can be made between the endpoint values of the range, between the endpoint values and the specific point values within the range, and between the specific point values to obtain one or more new numerical ranges, and these new numerical ranges should also be regarded as specifically disclosed herein.

[0040] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined in this document and its definition is different from the common understanding in the art, the definition in this document shall prevail.

[0041] In this document, any matter or thing not mentioned, except for the clearly stated content, directly applies to those known in the art without any change. Moreover, any embodiment described in this document can be freely combined with one or more other embodiments described in this document, and the technical solutions or technical ideas formed thereby shall be regarded as part of the original disclosure or original record of the present invention and should not be regarded as new content not disclosed or anticipated in this document, unless those skilled in the art consider that the combination is obviously unreasonable.

[0042] All patents and non-patent documents mentioned in this document, including but not limited to textbooks and journal articles, etc., are incorporated herein by reference in their entirety.

[0043] According to the present invention, the article or a part thereof can be manufactured by conventional means using the flame-retardant nylon material of the present invention and optional additional materials (such as antioxidants, inorganic fillers, etc.), for example, by injection molding, blow molding, extrusion molding, spinning, etc. The specific operations and conditions are well-known to those skilled in the art and can be selected according to actual needs, and will not be elaborated herein.

[0044] Example 1

[0045] Weigh 914 g (5 mol) of lysine hydrochloride, add 2.5 L of methanol, and then slowly add 515 g (5.25 mol) of concentrated sulfuric acid dropwise thereto. After the addition is complete, continue stirring and refluxing for 8 h. Transfer it to a large reaction kettle, continue to add methanol, and add a methanol solution containing 640 g (16 mol) of sodium hydroxide thereto. Continue stirring and reacting for 10 h. Evaporate the methanol to dryness, add 30 L of ethyl acetate for recrystallization, and after suction filtration, the weight of the white solid aminocaprolactam obtained is 320 g, and the yield is 48%. The test results of nuclear magnetic resonance hydrogen spectrum: 1 H NMR (D2O, 400 MHz) δ 3.25 - 3.35 (m, 1H), 3.15 - 3.25 (m, 2H), 1.50 - 2.15 (m, 4H).

[0046] Example 2

[0047] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dichloromethane. Cool the reaction system to -10 °C, and slowly add 134 g (500 mmol) of diphenyl chlorophosphate and 83 mL (600 mmol) of triethylamine. Return the reaction system to room temperature and stir for 3 h. Wash the reaction solution with saturated brine 3 times, dry it with anhydrous magnesium sulfate, evaporate it to dryness, and recrystallize it with acetone to obtain the bio-based flame retardant monomer (the side group R is structure F, where R1 = R2 = Ph, X1 = X2 = X3 = O) product, and the yield is 87%. The test results of nuclear magnetic resonance hydrogen spectrum: 1 H NMR (300 MHz, CDCl3) δ 7.45 - 7.29 (m, 10H), 5.83 (s, 1H), 4.05 (d, 1H), 3.09 - 2.90 (m, 2H), 1.99 (d, 2H), 1.70 (m, 2H), 1.45 (s, 2H).

[0048] Example 3

[0049] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dichloromethane. Cool the reaction system to -10 °C, and slowly add 130 g (800 mmol) of ethyl dichlorophosphate and 166 mL (1200 mmol) of triethylamine. Return the reaction system to room temperature and stir for 3 h, then add 200 mL of methanol and stir for 1 h. Wash the reaction solution with saturated brine 3 times, dry it with anhydrous magnesium sulfate, evaporate it to dryness, and recrystallize it with dichloromethane to obtain the bio-based flame retardant monomer (the side group R is structure F, where R1 = Me, R2 = Et, X1 = X2 = X3 = O) product, and the yield is 72%. The test results of nuclear magnetic resonance hydrogen spectrum: 11H NMR (300 MHz, CDCl3) δ 5.86 (s, 1H), 4.27 (t, 2H), 4.08 (d, 1H), 3.79 (s, 3H), 3.05 - 2.92 (m, 2H), 1.98 (d, 2H), 1.73 (m, 2H), 1.46 (s, 2H).

[0050] Example 4

[0051] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dimethylformamide. Cool the reaction system to -10 °C and slowly add 119 g (800 mmol) of methyl dichlorophosphate and 166 mL (1200 mmol) of triethylamine. Restore the reaction system to room temperature, stir for 3 h, add 200 mL of methanol, and stir for 1 h. Wash the reaction solution three times with saturated brine, dry it with anhydrous magnesium sulfate, evaporate to dryness, and recrystallize with methanol to obtain the bio-based flame retardant monomer (side group R is structure F, where R1 = R2 = Me, X1 = X2 = X3 = O) product with a yield of 42%. 1H NMR test results: 1 1H NMR (300 MHz, CDCl3) δ 5.87 (s, 1H), 4.06 (d, 1H), 3.81 (s, 6H), 3.06 - 2.93 (m, 2H), 1.92 (d, 2H), 1.75 (m, 2H), 1.43 (s, 2H).

[0052] Example 5

[0053] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dichloromethane. Cool the reaction system to -10 °C and slowly add 7.2 g (500 mmol) of dimethyl chlorophosphate and 83 mL (600 mmol) of triethylamine. Restore the reaction system to room temperature and stir for 3 h. Wash the reaction solution three times with saturated brine, dry it with anhydrous magnesium sulfate, evaporate to dryness, and recrystallize with dichloromethane to obtain the bio-based flame retardant monomer (side group R is structure F, where R1 = R2 = Me, X1 = X2 = X3 = O) product with a yield of 65%. 1H NMR test results: 1 1H NMR (300 MHz, CDCl3) δ 5.84 (s, 1H), 4.05 (d, 1H), 3.78 (s, 6H), 3.10 - 2.95 (m, 2H), 1.93 (d, 2H), 1.74 (m, 2H), 1.45 (s, 2H).

[0054] Example 6

[0055] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dichloromethane. Cool the reaction system to -10 °C and slowly add 71 g (500 mmol) of 2-chloro-2-oxo-1,3,2-dioxaphospholane and 48 mL (600 mmol) of pyridine. Restore the reaction system to room temperature and stir for 3 h. Wash the reaction solution three times with saturated brine, dry it with anhydrous magnesium sulfate, evaporate to dryness, and recrystallize with acetone to obtain the bio-based flame retardant monomer (the side group R is structure F, where R1, R2 = -CH2CH2-, X1 = X2 = X3 = O) product with a yield of 52%. The test results of 1H NMR are as follows: 1 H NMR(300MHz,CDCl3)δ5.84(s,1H),4.40(m,4H),4.07(d,1H),3.12-2.97(m,2H),1.98(d,2H),1.76(m,2H),1.43(s,2H).

[0056] Example 7

[0057] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dichloromethane. Cool the reaction system to -10 °C and slowly add 85 g (500 mmol) of bis(dimethylamino)phosphoryl chloride and 83 mL (600 mmol) of triethylamine. Restore the reaction system to room temperature and stir for 3 h. Wash the reaction solution three times with saturated brine, dry it with anhydrous magnesium sulfate, evaporate to dryness, and recrystallize with ethanol to obtain the bio-based flame retardant monomer (the side group R is structure F, where R1 = R2 = Me, X1 = X2 = NMe, X3 = O) product with a yield of 47%. The test results of 1H NMR are as follows: 1 H NMR(300MHz,CDCl3)δ5.86(s,1H),4.07(d,1H),3.13-2.98(m,2H),2.65(s,12H),1.96(d,2H),1.70(m,2H),1.42(s,2H).

[0058] Example 8

[0059] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1 and dissolve it in 500 mL of dichloromethane. Cool the reaction system to -10 °C and slowly add 78 g (500 mmol) of diethylphosphinous chloride and 83 mL (600 mmol) of triethylamine. Restore the reaction system to room temperature and stir for 3 h. Wash the reaction solution three times with saturated brine, dry it with anhydrous magnesium sulfate, evaporate to dryness, and recrystallize with acetone to obtain the bio-based flame retardant monomer (the side group R is structure C, where R1 = R2 = Et, X1 = X2 = O) product with a yield of 47%. The test results of 1H NMR are as follows:1 1H NMR (300 MHz, CDCl3) δ 4.06 (d, 1H), 3.85 (m, 4H), 3.12 - 2.93 (m, 2H), 1.94 (d, 2H), 1.75 (m, 2H), 1.46 (s, 2H), 1.25 (t, 6H).

[0060] Example 9

[0061] Take 64 g (500 mmol) of the aminocaprolactam prepared in Example 1, dissolve it in 500 mL of dichloromethane, cool the reaction system to -10 °C, and slowly add 106 g (800 mmol) of methyl dichlorophosphite and 83 mL (600 mmol) of triethylamine. Return the reaction system to room temperature, stir for 3 h, add 20 mL of methanol, and stir for 1 h. Wash the reaction solution three times with saturated brine, dry it with anhydrous magnesium sulfate, evaporate to dryness, and recrystallize with acetone to obtain the bio-based flame retardant monomer (side group R is structure C, where R1 = R2 = Me, X1 = X2 = O) product with a yield of 47%. 1H NMR test results: 1 1H NMR (300 MHz, CDCl3) δ 4.02 (d, 1H), 3.51 (m, 6H), 3.10 - 2.96 (m, 2H), 1.98 (d, 2H), 1.73 (m, 2H), 1.45 (s, 2H).

[0062] Example 10

[0063] Weigh 100 g (780 mmol) of the aminocaprolactam prepared in Example 1, add 100 mL of methanol, 105 mL (940 mmol) of benzaldehyde, and 105 g (1000 mmol) of anhydrous sodium carbonate, heat under reflux for 5 h, filter, add 252 g of DOPO (1170 mmol) to the filtrate, react for 3 h, and recrystallize with ethanol to obtain the bio-based flame retardant monomer (side group R is structure L, where R1 = Ph) product. The yield is 63%. 1H NMR test results: 1 1H NMR (300 MHz, CDCl3): δ 8.25 - 7.20 (m, 13H), 6.24 (s, 1H), 3.55 - 3.42 (m, 2H), 3.06 - 2.91 (m, 2H), 1.97 (d, 2H), 1.72 (m, 2H), 1.46 (s, 2H).

[0064] Example 11

[0065] Weigh 36.0 g (100 mmol) of the bio-based flame retardant monomer (prepared in Example 2) into a reaction kettle. After evacuating and replacing the gas three times, add 360 μL (20 mmol) of water. Under nitrogen protection, react in an oil bath at 195 °C for 8 h. After discharging, a bio-based macromolecular flame retardant product is obtained, with a yield of 62%, and the number-average molecular weight measured by GPC is 11.4 kDa. The test results of nuclear magnetic resonance hydrogen spectrum: 1 H NMR (300 MHz, CDCl3) δ 7.46 - 7.28 (m, 10H), 5.89 (m, 1H), 4.07 (m, 1H), 3.05 - 2.92 (m, 2H), 2.03 - 1.46 (m, 6H).

[0066] Example 12

[0067] Weigh 26.4 g (100 mmol) of the bio-based flame retardant monomer (prepared in Example 4) into a reaction kettle. After evacuating and replacing the gas three times, add 360 μL (20 mmol) of water. Under argon protection, react in an oil bath at 180 °C for 6 h. After discharging, a bio-based macromolecular flame retardant product is obtained, with a yield of 67%, and the number-average molecular weight measured by GPC is 9.5 kDa. The test results of nuclear magnetic resonance hydrogen spectrum: 1 H NMR (300 MHz, CDCl3) δ 5.62 (m, 1H), 4.05 - 3.82 (m, 7H), 3.04 - 2.92 (m, 2H), 1.92 - 1.45 (m, 6H).

[0068] Example 13

[0069] Weigh 23.5 g (100 mmol) of the bio-based flame retardant monomer (prepared in Example 6) into a reaction kettle. After evacuating and replacing the gas three times, add 360 μL (20 mmol) of water. Under nitrogen protection, react in an oil bath at 165 °C for 12 h. After discharging, a bio-based macromolecular flame retardant product is obtained, with a yield of 56%, and the number-average molecular weight measured by GPC is 12.8 kDa. The test results of nuclear magnetic resonance hydrogen spectrum: 1 H NMR (300 MHz, CDCl3) δ 5.84 (s, 1H), 4.42 - 4.06 (m, 5H), 3.13 - 2.96 (m, 2H), 1.98 - 1.43 (m, 6H).

[0070] Example 14

[0071] Weigh 26.2 g (100 mmol) of the bio-based flame retardant monomer (prepared in Example 7) into a reaction kettle. After evacuating and replacing the gas three times, add 360 μL (20 mmol) of water. Under argon protection, react in an oil bath at 195 °C for 24 h. After discharging, a bio-based macromolecular flame retardant product is obtained, with a yield of 63%, and the number-average molecular weight measured by GPC is 7.9 kDa. The test results of nuclear magnetic resonance hydrogen spectrum: 11H NMR (300 MHz, CDCl3) δ 5.95 (m, 1H), 4.08 (m, 1H), 3.17 - 2.66 (m, 14H), 2.02 - 1.40 (m, 6H).

[0072] Example 15

[0073] Weigh 15.6 g (100 mmol) of the bio - based flame - retardant monomer (prepared in Example 8) into a reaction kettle. After evacuating and replacing the gas three times, add 360 μL (20 mmol) of water. Under nitrogen protection, react at 185 °C in an oil bath for 3 h. After discharging, a bio - based macromolecular flame - retardant product is obtained, with a yield of 45% and a number - average molecular weight of 13.6 kDa measured by GPC. The results of 1H nuclear magnetic resonance spectroscopy are as follows: 1 1H NMR (300 MHz, CDCl3) δ 4.03 - 3.80 (m, 5H), 3.17 - 2.93 (m, 2H), 1.90 - 1.22 (m, 12H).

[0074] Example 16

[0075] Mix 1 g of the bio - based macromolecular flame - retardant (prepared in Example 11), 15 g of nylon 6, and 0.02 g of antioxidant on a micro twin - screw extruder. The screw speed of the twin - screw extruder is 100 rpm, and the temperature in the middle section and the extrusion temperature of the twin - screw extruder are 260 °C to obtain a flame - retardant nylon material.

[0076] Example 17

[0077] Mix 1 g of the bio - based macromolecular flame - retardant (prepared in Example 12), 15 g of nylon 66, and 0.02 g of antioxidant on a micro twin - screw extruder. The screw speed of the twin - screw extruder is 100 rpm, and the temperature in the middle section and the extrusion temperature of the twin - screw extruder are 270 °C to obtain a flame - retardant nylon material.

[0078] Example 18

[0079] Mix 1 g of the bio - based macromolecular flame - retardant (prepared in Example 13), 15 g of nylon 11, and 0.02 g of antioxidant on a micro twin - screw extruder. The screw speed of the twin - screw extruder is 150 rpm, and the temperature in the middle section and the extrusion temperature of the twin - screw extruder are 280 °C to obtain a flame - retardant nylon material.

[0080] Example 19

[0081] Mix 1 g of the bio - based macromolecular flame - retardant (prepared in Example 14), 15 g of nylon 12, and 0.02 g of antioxidant on a micro twin - screw extruder. The screw speed of the twin - screw extruder is 100 rpm, and the temperature in the middle section and the extrusion temperature of the twin - screw extruder are 275 °C to obtain a flame - retardant nylon material.

[0082] Example 20

[0083] 1 g of the bio-based macromolecular flame retardant (prepared in Example 15) was blended with 10 g of nylon 6 and 0.02 g of antioxidant on a micro twin-screw extruder. The screw speed of the twin-screw extruder was 100 rpm, and the temperature in the middle section and the extrusion temperature of the twin-screw extruder were 260 °C to obtain a flame-retardant nylon material.

[0084] Comparative Example 1

[0085] 50 g of caprolactam (440 mmol) was weighed, melted by heating in a reaction kettle, and 1.5 mL (83 mmol) of water was added. Under the conditions of 190 °C and 0.8 MPa, the pressure reaction was carried out for 6 h. Under the conditions of 210 °C and 0 MPa, the atmospheric pressure reaction was carried out for 1 h. Under the conditions of 210 °C and -0.1 MPa, the reduced pressure reaction was carried out for 1 h. The product was discharged and pelletized to obtain a homopolymer nylon material with a yield of 85%. The number-average molecular weight measured by GPC was 26.3 kDa. 1 H NMR (500 MHz, TFA / CDCl3, 1:5, v:v): δ 3.25 - 3.17 (m, 2H), 2.25 - 2.19 (m, 2H), 1.78 - 1.16 (m, 6H).

[0086] Comparative Example 2

[0087] 2 g of red phosphorus flame retardant was blended with 15 g of nylon 6 (prepared in Comparative Example 1) and 0.02 g of antioxidant on a micro twin-screw extruder. The screw speed of the twin-screw extruder was 100 rpm, and the temperature in the middle section and the extrusion temperature of the twin-screw extruder were 260 °C to obtain a comparative nylon material.

[0088] Comparative Example 3

[0089] 0.05 g of the bio-based macromolecular flame retardant (prepared in Example 11) was blended with 15 g of nylon 6 and 0.02 g of antioxidant on a micro twin-screw extruder. The screw speed of the twin-screw extruder was 100 rpm, and the temperature in the middle section and the extrusion temperature of the twin-screw extruder were 260 °C to obtain a comparative nylon material.

[0090] Effect Example 1

[0091] Flame retardancy test:

[0092] The flame-retardant nylon materials prepared in Examples 16 - 20 and the nylon materials prepared in Comparative Examples 1 - 3 were respectively injection-molded into strip specimens of 125 mm × 13 mm × 5 mm. The vertical burning test was carried out according to the method described in Section 3.14 of the V classification in UL94 and Section 9.2.4 of GB / T 2408 - 2008. The results were recorded according to the V classification standard, as shown in Table 1.

[0093] The flame-retardant nylon materials prepared in Examples 16-20 and the nylon materials prepared in Comparative Examples 1-3 were respectively injection-molded into strip specimens of 80 mm × 10 mm × 4 mm, and the limiting oxygen index of the specimens was tested according to the method described in GB / T 2406.2-2009. The results are shown in Table 1.

[0094] Effect Example 2

[0095] Mechanical property test

[0096] The flame-retardant nylon materials prepared in Examples 16-20 and the nylon materials prepared in Comparative Examples 1-3 were respectively injection-molded into 5A specimens (dimensions refer to Chinese national standard GB / T 1040.2-2022), and the tensile properties were tested. The results are shown in Table 1.

[0097] Table 1

[0098]

[0099]

[0100] The experimental data in Table 1 can prove that the flame-retardant performance of the flame-retardant nylon material of the present invention has achieved a breakthrough improvement. Examples 16-20 all reached UL94 V-0 level (self-extinguishing time < 10 s), achieving a leap in the flame-retardant grade compared with the V-2 level (self-extinguishing time > 30 s) of the basic nylon (Comparative Example 1); the LOI value increased from 24% of the basic nylon to 35%-39% (an increase of 46%-62.5%). Example 20 reached the highest LOI of 39%, which is related to the gas-phase flame-retardant synergistic effect of the bis(ethoxy)phosphorus structure in its flame-retardant monomer. It is equivalent to the LOI of 37% of the red phosphorus system, but avoids the toxicity and color problems of red phosphorus. In addition, the mechanical properties of the flame-retardant nylon material of the present invention are basically equivalent to those of conventional nylon materials. The tensile strength of Examples 16-19 reached 93%-95% of the strength of the matrix nylon, and Example 20 reached 78 MPa, which is attributed to the hydrogen bond synergistic effect between the ethoxy side chain and the nylon 6 molecular chain. In contrast, the strength loss of the red phosphorus system reached 32.9%, highlighting the structural advantages of the macromolecular flame retardant.

[0101] In summary, through precise molecular design, the present invention has achieved synergistic optimization in three dimensions: flame-retardant efficiency (LOI > 35%), mechanical retention rate (> 90%), and environmental friendliness, solving the long-existing "performance-environmental protection" trade-off problem in the flame-retardant field and providing a reliable technical path for the green upgrading of engineering plastics.

[0102] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0103] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination manners.

[0104] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content invented by the present invention.

Claims

1. A bio-based macromolecular flame retardant, characterized in that, The structural formula is as follows: In the formula, R is selected from one of the following structures A to V: Among them, R1 and R2 are each independently selected from hydrogen, C 1-28 substituted / unsubstituted straight-chain / branched saturated / unsaturated aliphatic hydrocarbon groups, substituted / unsubstituted saturated / unsaturated C 3-15 alicyclic hydrocarbon groups, substituted / unsubstituted C 6-22 aryl groups, substituted / unsubstituted saturated / unsaturated C 7-35 aralkyl groups; wherein the aromatic rings in the aryl group and the aralkyl group have any number of nitrogen atoms as heteroatoms; X1, X2, and X3 are each independently selected from an oxygen atom, a methylene group, and a substituted imino group; The substitution means that the group is substituted by one or more substituents, and the substituents are halogen, nitro, hydroxy, cyano, boric acid group, borate group, C 1-18 linear / branched alkyl, C 1-18 linear / branched alkoxy, C 1-18 linear / branched alkylamino.

2. A preparation method of the bio-based macromolecular flame retardant as described in claim 1, characterized in that, It includes the following steps: S1. Dissolve aminocaprolactam in a solvent, add a phosphorus-containing small molecule and an auxiliary agent, fully react, evaporate the solvent, and obtain a bio-based flame retardant monomer after post-treatment; S2. Under an inert gas condition, add the bio-based flame retardant monomer into a reaction kettle, evacuate and then fill with inert gas and repeat three times, and then add water for polymerization reaction. After the polymerization is completed, discharge to obtain a bio-based macromolecular flame retardant; The auxiliary agent is selected from one or more of aldehyde, amine, alcohol, and hydrazine; The phosphorus-containing small molecule is selected from one or more of the molecules with the following structures: In the formula, X is a halogen.

3. The preparation method of the bio-based macromolecular flame retardant according to claim 2, wherein, The phosphorus-containing small molecule is selected from one or more of phosphorus trichloride, phosphorus oxychloride, dimethyl chlorophosphate, diethyl chlorophosphate, phenylphosphoryl chloride, dimethylphosphoryl chloride, diethylphosphoryl chloride, diphenylphosphoryl chloride, trimethyl phosphate, triethyl phosphate, dimethyl phenyl phosphate, diethyl phenyl phosphate, methyl diphenyl phosphate, ethyl diphenyl phosphate, dimethyl phosphinous chloride, diethyl phosphinous chloride, dibutyl phosphinous chloride, trimethyl phosphite, triethyl phosphite, hexachlorocyclotriphosphazene, and DOPO; 4. The preparation method of the bio-based macromolecular flame retardant according to claim 2, characterized in that, The solvent is selected from one or more of diethyl ether, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, dichloromethane, chloroform, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and water; 5. The preparation method of the bio-based macromolecular flame retardant according to claim 2, wherein, The reaction time in step S1 is 0.5 h to 24 h, and the reaction temperature is -50°C to 200°C.

6. The preparation method of the bio-based macromolecular flame retardant according to claim 2, characterized in that, The post-treatment in step S1 is one or more of preparative chromatography, column chromatography, sublimation purification, and recrystallization; the solvent used for recrystallization is a mixture of one or more of petroleum ether, methanol, ethanol, propanol, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethyl acetate, isoamyl acetate, acetonitrile, methyl ethyl ketone, acetone, dichloromethane, chloroform, carbon tetrachloride, N,N-dimethylformamide, pyridine, dimethyl sulfoxide, and water; 7. The preparation method of the bio-based macromolecular flame retardant according to claim 2, wherein Before the vacuum pumping described in step S2, a catalyst is also added; the catalyst is selected from hydrides / oxyacids of halogens, oxyacids of sulfur, nitrogen / phosphorus, C 1-35 1-5 yuan carboxylic acids / hydroxy acids / amino acids / sulfonic acids / phosphoric acids, hydroxides, carbonates, bicarbonates, basic carbonates of alkali metals / alkaline earth metals; the molar ratio of the catalyst to the bio-based flame retardant monomer is 0.001-0.1:

1.

8. The preparation method of the bio-based macromolecular flame retardant according to claim 2, wherein The mass ratio of the bio-based flame retardant monomer to water in step S2 is 10 to 200:

1.

9. The preparation method of the bio-based macromolecular flame retardant according to claim 2, characterized in that, The conditions for the polymerization reaction in step S2 are: The polymerization temperature is 140°C to 320°C; the polymerization time is 2 h to 96 h; the polymerization pressure is -0.1 MPa to 5 MPa.

10. A flame-retardant nylon material, characterized in that, It includes the following components by weight percentage: 70% to 99% of nylon resin, 1% to 30% of the bio-based macromolecular flame retardant described in claim 1; The nylon resin is an aliphatic, aromatic or semi-aromatic nylon resin.

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