High flame-retardant composite material for 3D printing and preparation method thereof

Abstract

The application discloses a kind of high flame-retardant composite materials for 3D printing and preparation method thereof, to be uniformly mixed with terephthalic acid, adipic acid, modified monomer, hexanediol and molybdenum oxide, terephthalic acid, adipic acid, modified monomer and hexanediol esterification condensation, internal include molybdenum oxide, and high flame-retardant composite materials for 3D printing are prepared, when burning, organic phosphorus in modified monomer is decomposed to form a layer of dense and porous carbon layer, side chain contains polysiloxane segment can be reinforced to loose carbon layer formed by phosphorus catalysis into dense, stable physical barrier, schiff base structure can open to form nitrogen free radical, crosslinking occurs with polyester molecular chain, form nitrogen-containing crosslinking network, cage-type silsesquioxane structure, form ceramic skeleton inside carbon layer, molybdenum oxide can catalyze polyester to form more carbon layer when burning, so that the density of carbon layer produced is further improved, effectively reduce the smoke generated when composite material burns.

Description

Technical Field

[0001] This invention relates to the field of polyester material preparation technology, specifically to a high flame-retardant composite material for 3D printing and its preparation method. Background Technology

[0002] The rapid development of 3D printing technologies such as fused deposition modeling has created an urgent demand for high-performance, functional printing materials. Polyester materials, especially polyethylene terephthalate (PET), polyethylene terephthalate-1,4-cyclohexanediol (PET-1,4-cyclohexanediol), and polylactic acid (PLA), have become important 3D printing consumable matrices due to their good mechanical properties, processing adaptability, and relatively low cost. However, most general-purpose polyesters are flammable materials with low limiting oxygen indexes. When burning, they produce severe molten dripping and large amounts of smoke, posing significant fire safety hazards and greatly limiting their application in fields with strict flame retardancy requirements, such as electronics, transportation, and architectural interiors. Summary of the Invention

[0003] The purpose of this invention is to provide a high flame-retardant composite material for 3D printing and its preparation method, which solves the problem that polyester materials have poor flame-retardant effect and produce a lot of smoke when burning.

[0004] The objective of this invention can be achieved through the following technical solutions: A method for preparing a highly flame-retardant composite material for 3D printing specifically includes the following steps: Terephthalic acid, adipic acid, modified monomers, ethylene glycol, and molybdenum oxide were mixed evenly and protected with nitrogen gas. The mixture was heated to 140-150°C at a rotation speed of 120-150 r / min and a heating rate of 1-2°C. Tetrabutyl titanate was then added, and the mixture was heated to 210-220°C for 3-4 hours. The mixture was then heated to 250-260°C at a heating rate of 0.5-1°C and the pressure was adjusted to 500-600 Pa for 2-3 hours to obtain a high flame-retardant composite material for 3D printing.

[0005] Furthermore, the molar ratio of terephthalic acid, adipic acid, modified monomer, and ethylene glycol is 4:1:0.2:4.7, the amount of molybdenum oxide is 3% of the total mass of terephthalic acid, adipic acid, modified monomer, and ethylene glycol, and the amount of tetrabutyl titanate is 0.4‰ of the total mass of terephthalic acid and adipic acid.

[0006] Furthermore, the modified monomer is prepared by the following steps: Step A1: Dissolve pentaerythritol phosphate in dioxane, purge with nitrogen, and stir at 150-200 r / min and 20-25℃. Add epichlorohydrin and boron trifluoride ether, heat to 90-100℃ and react for 2-4 h. Then cool to 40-60℃, add sodium hydroxide solution, and react for 2-3 h to obtain the modifier. Step A2: Mix octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water, purge with nitrogen, and react for 10-12 hours at a speed of 150-200 r / min and a temperature of 90-95℃. Then raise the temperature to 105-110℃ and continue the reaction for 2-3 hours to obtain aminopolysiloxane. Step A3: Mix aminopolysiloxane, modifier and N,N-dimethylformamide, purge with nitrogen, and react for 6-8 hours at 200-300 r / min and 70-80℃ to obtain pretreated polysiloxane. Mix pretreated polysiloxane, 4-formylphenylboronic acid, 5A molecular sieve and xylene, purge with nitrogen, and react for 12-15 hours at 150 r / min and 60-70℃ to obtain functionalized polysiloxane. Step A4: Functionalized polysiloxane, aminocage-type silsesquioxane, 5A molecular sieve and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 4-6 hours at a rotation speed of 200-300 r / min and a temperature of 40-50℃ to obtain modified polysiloxane. Modified polysiloxane, allyl alcohol, caster catalyst and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 8-10 hours at a rotation speed of 120-150 r / min and a temperature of 80-85℃ to obtain modified monomer.

[0007] Furthermore, in step A1, the ratio of pentaerythritol phosphate, epichlorohydrin, and sodium hydroxide solution is 1 mol: 1 mol: 200 mL, the mass fraction of sodium hydroxide solution is 40%, and the amount of boron trifluoride ether is 0.4% of the mass of epichlorohydrin.

[0008] Furthermore, the ratio of octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water in step A2 is 1.1 mol: 0.1 mol: 1 mol: 1.5 mol: 30 mL.

[0009] Furthermore, in step A3, the molar ratio of amino groups and modifiers on the amino polysiloxane is 1:2, and the ratio of hydroxyl groups, 4-formylphenylboronic acid, and 5A molecular sieve on the pretreated polysiloxane is 7.5 mmol:15 mmol:2 g.

[0010] Furthermore, in step A4, the ratio of aldehyde group, amino cage-type silsesquioxane and 5A molecular sieve on the functionalized polysiloxane is 20 mmol:20 mmol:5 g, the molar ratio of modified polysiloxane and allyl alcohol is 1:2, and the molar ratio of caster catalyst is 0.01% of the mass of allyl alcohol.

[0011] Furthermore, the aminocage-type silsesquioxane is prepared by the following steps: Methyltrichlorosilane and acetone were mixed and stirred at 300-500 r / min and 50-55℃, while deionized water was added. The mixture was then heated to 80-90℃ and reacted for 4-6 h to obtain the T7 precursor. The T7 precursor, triethylamine, and tetrahydrofuran were mixed and stirred at 150-200 r / min and 65-70℃, while aminopropyltriethoxysilane and dibutyltin dilaurate were added. The mixture was then reacted for 20-25 h, and the pH was adjusted to neutral to obtain an aminocage-type silsesquioxane.

[0012] Furthermore, the molar ratio of methyltrichlorosilane, acetone and deionized water is 1:10:1.5, and the ratio of the amount of T7 precursor, triethylamine, tetrahydrofuran, aminopropyltriethoxysilane and dibutyltin dilaurate is 1 mol:1.2 mol:5 L:1 mol:0.9 g.

[0013] The beneficial effects of this invention: This invention discloses a high flame-retardant composite material for 3D printing, prepared by uniformly mixing terephthalic acid, adipic acid, modified monomers, hexanediol, and molybdenum oxide, followed by esterification and condensation of terephthalic acid, adipic acid, modified monomers, and hexanediol, containing molybdenum oxide internally. The modified monomer is prepared using pentaerythritol phosphate and epichlorohydrin as raw materials, allowing the hydroxyl groups on pentaerythritol phosphate to react with the epoxy groups on epichlorohydrin, followed by ring closure in the presence of sodium hydroxide solution to form new epoxy groups, thus obtaining a modifier. Octamethylcyclotetrasiloxane is ring-opened, hydrolyzed and condensed with 3-aminopropyldiethyloxymethylsilane, and then end-capped with tetramethyldisiloxane to obtain an aminopolysiloxane. The reaction of an alkyl group with a modifier causes the amino group on the amino polysiloxane to react with the epoxy group on the modifier to form a hydroxyl group, thus obtaining a pretreated polysiloxane. The pretreated polysiloxane is then reacted with 4-formylphenylboronic acid, causing the two hydroxyl groups on the same tertiary amine nitrogen atom of the pretreated polysiloxane to react with the boric acid on the 4-formylphenylboronic acid atom, forming a cyclic borate ester, thus obtaining a functionalized polysiloxane. The functionalized polysiloxane is then reacted with an amino-cage silsesquioxane, causing the aldehyde group on the functionalized polysiloxane to react with the amino group on the amino-cage silsesquioxane, forming a Schiff base structure, thus obtaining a modified polysiloxane. Finally, the modified polysiloxane is reacted with allyl alcohol, causing the Si-H bond on the modified polysiloxane to react with the double bond on the allyl alcohol atom, thus obtaining a modified monomer.

[0014] The aminocage-type silsesquioxane was prepared by hydrolysis and condensation of methyltrichlorosilane to obtain the T7 precursor. The T7 precursor was then reacted with aminopropyltriethoxysilane to complete the vertex capping process, thus obtaining the aminocage-type silsesquioxane.

[0015] During combustion, the organophosphorus compounds in the modified monomers decompose upon heating to generate highly dehydrating substances such as phosphoric acid, metaphosphoric acid, and polyphosphoric acid. These acidic substances catalyze a series of reactions in the polyester matrix, including dehydration, crosslinking, and cyclization, accelerating the formation of a dense and porous carbon layer. The side chains containing polysiloxane segments can strengthen the loose carbon layer formed by phosphorus catalysis into a dense and stable physical barrier. The Schiff base structure can open to form nitrogen free radicals, which crosslink with the polyester molecular chains to form a nitrogen-containing crosslinking network. The cage-like silsesquioxane structure forms a ceramic skeleton inside the elastic layer. Molybdenum oxide can catalyze the formation of more carbon layers in the polyester during combustion, further improving the density of the carbon layer and effectively reducing the smoke generated during the combustion of the composite material. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: A method for preparing a highly flame-retardant composite material for 3D printing, specifically including the following steps: Terephthalic acid, adipic acid, modified monomers, ethylene glycol, and molybdenum oxide were mixed evenly and protected with nitrogen gas. The mixture was heated to 140°C at a rotation speed of 120 r / min and a heating rate of 1°C. Tetrabutyl titanate was then added, and the mixture was heated to 210°C for 3 hours. The mixture was then heated to 250°C at a heating rate of 0.5°C and the pressure was adjusted to 500 Pa for 2 hours to obtain a high flame-retardant composite material for 3D printing.

[0018] The molar ratio of terephthalic acid, adipic acid, modified monomer, and ethylene glycol is 4:1:0.2:4.7. The amount of molybdenum oxide is 3% of the total mass of terephthalic acid, adipic acid, modified monomer, and ethylene glycol. The amount of tetrabutyl titanate is 0.4‰ of the total mass of terephthalic acid and adipic acid.

[0019] The modified monomer is prepared by the following steps: Step A1: Dissolve pentaerythritol phosphate in dioxane, purge with nitrogen, stir at 150 r / min and 20°C, add epichlorohydrin and boron trifluoride ether, heat to 90°C and react for 2 h, then cool to 40°C, add sodium hydroxide solution and react for 2 h to obtain the modifier; Step A2: Mix octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water, purge with nitrogen, and react for 10 h at a speed of 150 r / min and a temperature of 90 °C. Then raise the temperature to 105 °C and continue the reaction for 2 h to obtain aminopolysiloxane. Step A3: Mix amino polysiloxane, modifier and N,N-dimethylformamide, purge with nitrogen, and react for 6 h at 200 r / min and 70 °C to obtain pretreated polysiloxane. Mix pretreated polysiloxane, 4-formylphenylboronic acid, 5A molecular sieve and xylene, purge with nitrogen, and react for 12 h at 150 r / min and 60 °C to obtain functionalized polysiloxane. Step A4: Functionalized polysiloxane, aminocage-type silsesquioxane, 5A molecular sieve and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 4 hours at a rotation speed of 200 r / min and a temperature of 40℃ to obtain modified polysiloxane. Modified polysiloxane, allyl alcohol, caster catalyst and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 8 hours at a rotation speed of 120 r / min and a temperature of 80℃ to obtain modified monomer.

[0020] The ratio of pentaerythritol phosphate, epichlorohydrin and sodium hydroxide solution used in step A1 is 1 mol: 1 mol: 200 mL, the mass fraction of sodium hydroxide solution is 40%, and the amount of boron trifluoride ether used is 0.4% of the mass of epichlorohydrin.

[0021] The ratio of octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water used in step A2 is 1.1 mol: 0.1 mol: 1 mol: 1.5 mol: 30 mL.

[0022] The molar ratio of amino groups and modifiers on the amino polysiloxane described in step A3 is 1:2, and the ratio of hydroxyl groups, 4-formylphenylboronic acid, and 5A molecular sieves on the pretreated polysiloxane is 7.5 mmol:15 mmol:2 g.

[0023] In step A4, the ratio of aldehyde group, amino cage-type silsesquioxane and 5A molecular sieve on the functionalized polysiloxane is 20 mmol:20 mmol:5 g, the molar ratio of modified polysiloxane and allyl alcohol is 1:2, and the molar ratio of caster catalyst is 0.01% of the mass of allyl alcohol.

[0024] The aminocage-type silsesquioxane is prepared by the following steps: Methyltrichlorosilane and acetone were mixed and stirred at 300 r / min and 50 °C, while deionized water was added. The mixture was then heated to 80 °C and reacted for 4 h to obtain the T7 precursor. The T7 precursor, triethylamine, and tetrahydrofuran were mixed and stirred at 150 r / min and 65 °C, while aminopropyltriethoxysilane and dibutyltin dilaurate were added. The mixture was then reacted for 20 h, and the pH was adjusted to neutral to obtain an aminocage-type silsesquioxane.

[0025] The molar ratio of methyltrichlorosilane, acetone and deionized water is 1:10:1.5, and the ratio of the amount of T7 precursor, triethylamine, tetrahydrofuran, aminopropyltriethoxysilane and dibutyltin dilaurate is 1 mol:1.2 mol:5 L:1 mol:0.9 g.

[0026] Example 2, a method for preparing a highly flame-retardant composite material for 3D printing, specifically includes the following steps: Terephthalic acid, adipic acid, modified monomers, ethylene glycol, and molybdenum oxide were mixed evenly and protected with nitrogen gas. The mixture was heated to 145°C at a rotation speed of 120 r / min and a heating rate of 2°C. Tetrabutyl titanate was then added, and the mixture was heated to 210°C for 4 hours. The mixture was then heated to 255°C at a heating rate of 0.5°C and the pressure was adjusted to 550 Pa for 2 hours to obtain a high flame-retardant composite material for 3D printing.

[0027] The molar ratio of terephthalic acid, adipic acid, modified monomer, and ethylene glycol is 4:1:0.2:4.7. The amount of molybdenum oxide is 3% of the total mass of terephthalic acid, adipic acid, modified monomer, and ethylene glycol. The amount of tetrabutyl titanate is 0.4‰ of the total mass of terephthalic acid and adipic acid.

[0028] The modified monomer is prepared by the following steps: Step A1: Dissolve pentaerythritol phosphate in dioxane, purge with nitrogen, stir at 150 r / min and 25°C, add epichlorohydrin and boron trifluoride ether, heat to 95°C and react for 3 h, then cool to 50°C, add sodium hydroxide solution and react for 2 h to obtain the modifier; Step A2: Mix octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water, purge with nitrogen, and react for 12 hours at a speed of 150 r / min and a temperature of 95°C. Then raise the temperature to 105°C and continue the reaction for 3 hours to obtain aminopolysiloxane. Step A3: Mix aminopolysiloxane, modifier and N,N-dimethylformamide, purge with nitrogen, and react for 7 h at 200 r / min and 75 °C to obtain pretreated polysiloxane. Mix pretreated polysiloxane, 4-formylphenylboronic acid, 5A molecular sieve and xylene, purge with nitrogen, and react for 15 h at 150 r / min and 65 °C to obtain functionalized polysiloxane. Step A4: Functionalized polysiloxane, aminocage-type silsesquioxane, 5A molecular sieve and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 5 hours at a rotation speed of 200 r / min and a temperature of 45℃ to obtain modified polysiloxane. Modified polysiloxane, allyl alcohol, caster catalyst and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 9 hours at a rotation speed of 120 r / min and a temperature of 85℃ to obtain modified monomer.

[0029] The ratio of pentaerythritol phosphate, epichlorohydrin and sodium hydroxide solution used in step A1 is 1 mol: 1 mol: 200 mL, the mass fraction of sodium hydroxide solution is 40%, and the amount of boron trifluoride ether used is 0.4% of the mass of epichlorohydrin.

[0030] The ratio of octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water used in step A2 is 1.1 mol: 0.1 mol: 1 mol: 1.5 mol: 30 mL.

[0031] The molar ratio of amino groups and modifiers on the amino polysiloxane described in step A3 is 1:2, and the ratio of hydroxyl groups, 4-formylphenylboronic acid, and 5A molecular sieves on the pretreated polysiloxane is 7.5 mmol:15 mmol:2 g.

[0032] In step A4, the ratio of aldehyde group, amino cage-type silsesquioxane and 5A molecular sieve on the functionalized polysiloxane is 20 mmol:20 mmol:5 g, the molar ratio of modified polysiloxane and allyl alcohol is 1:2, and the molar ratio of caster catalyst is 0.01% of the mass of allyl alcohol.

[0033] The aminocage-type silsesquioxane is prepared by the following steps: Methyltrichlorosilane and acetone were mixed and stirred at 500 r / min and 50 °C, while deionized water was added. The mixture was then heated to 85 °C and reacted for 5 h to obtain the T7 precursor. The T7 precursor, triethylamine, and tetrahydrofuran were mixed and stirred at 150 r / min and 70 °C, while aminopropyltriethoxysilane and dibutyltin dilaurate were added. The mixture was then reacted for 25 h, and the pH was adjusted to neutral to obtain an aminocage-type silsesquioxane.

[0034] The molar ratio of methyltrichlorosilane, acetone and deionized water is 1:10:1.5, and the ratio of the amount of T7 precursor, triethylamine, tetrahydrofuran, aminopropyltriethoxysilane and dibutyltin dilaurate is 1 mol:1.2 mol:5 L:1 mol:0.9 g.

[0035] Example 3: A method for preparing a highly flame-retardant composite material for 3D printing, specifically including the following steps: Terephthalic acid, adipic acid, modified monomers, ethylene glycol, and molybdenum oxide were mixed evenly and protected with nitrogen gas. The mixture was heated to 150°C at a rotation speed of 150 r / min and a heating rate of 2°C. Tetrabutyl titanate was then added, and the mixture was heated to 220°C for 4 hours. The mixture was then heated to 260°C at a heating rate of 1°C and the pressure was adjusted to 600 Pa for 3 hours to obtain a high flame-retardant composite material for 3D printing.

[0036] The molar ratio of terephthalic acid, adipic acid, modified monomer, and ethylene glycol is 4:1:0.2:4.7. The amount of molybdenum oxide is 3% of the total mass of terephthalic acid, adipic acid, modified monomer, and ethylene glycol. The amount of tetrabutyl titanate is 0.4‰ of the total mass of terephthalic acid and adipic acid.

[0037] The modified monomer is prepared by the following steps: Step A1: Dissolve pentaerythritol phosphate in dioxane, purge with nitrogen, stir at 200 r / min and 25°C, add epichlorohydrin and boron trifluoride ether, heat to 100°C and react for 4 h, then cool to 60°C, add sodium hydroxide solution and react for 3 h to obtain the modifier; Step A2: Mix octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water, purge with nitrogen, and react for 12 hours at a speed of 200 r / min and a temperature of 95°C. Then raise the temperature to 110°C and continue the reaction for 3 hours to obtain aminopolysiloxane. Step A3: Mix aminopolysiloxane, modifier and N,N-dimethylformamide, purge with nitrogen, and react for 8 hours at 300 r / min and 80℃ to obtain pretreated polysiloxane. Mix pretreated polysiloxane, 4-formylphenylboronic acid, 5A molecular sieve and xylene, purge with nitrogen, and react for 15 hours at 150 r / min and 70℃ to obtain functionalized polysiloxane. Step A4: Functionalized polysiloxane, aminocage-type silsesquioxane, 5A molecular sieve and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 6 hours at a rotation speed of 300 r / min and a temperature of 50℃ to obtain modified polysiloxane. Modified polysiloxane, allyl alcohol, caster catalyst and N,N-dimethylformamide are mixed, and under nitrogen protection, the mixture is reacted for 10 hours at a rotation speed of 150 r / min and a temperature of 85℃ to obtain modified monomer.

[0038] The ratio of pentaerythritol phosphate, epichlorohydrin and sodium hydroxide solution used in step A1 is 1 mol: 1 mol: 200 mL, the mass fraction of sodium hydroxide solution is 40%, and the amount of boron trifluoride ether used is 0.4% of the mass of epichlorohydrin.

[0039] The ratio of octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water used in step A2 is 1.1 mol: 0.1 mol: 1 mol: 1.5 mol: 30 mL.

[0040] The molar ratio of amino groups and modifiers on the amino polysiloxane described in step A3 is 1:2, and the ratio of hydroxyl groups, 4-formylphenylboronic acid, and 5A molecular sieves on the pretreated polysiloxane is 7.5 mmol:15 mmol:2 g.

[0041] In step A4, the ratio of aldehyde group, amino cage-type silsesquioxane and 5A molecular sieve on the functionalized polysiloxane is 20 mmol:20 mmol:5 g, the molar ratio of modified polysiloxane and allyl alcohol is 1:2, and the molar ratio of caster catalyst is 0.01% of the mass of allyl alcohol.

[0042] The aminocage-type silsesquioxane is prepared by the following steps: Methyltrichlorosilane and acetone were mixed and stirred at 500 r / min and 55 °C, while deionized water was added. The mixture was then heated to 90 °C and reacted for 6 h to obtain the T7 precursor. The T7 precursor, triethylamine, and tetrahydrofuran were mixed and stirred at 200 r / min and 70 °C, while aminopropyltriethoxysilane and dibutyltin dilaurate were added. The mixture was then reacted for 25 h, and the pH was adjusted to neutral to obtain an aminocage-type silsesquioxane.

[0043] The molar ratio of methyltrichlorosilane, acetone and deionized water is 1:10:1.5, and the ratio of the amount of T7 precursor, triethylamine, tetrahydrofuran, aminopropyltriethoxysilane and dibutyltin dilaurate is 1 mol:1.2 mol:5 L:1 mol:0.9 g.

[0044] Comparative Example 1: This comparative example did not include molybdenum oxide, but the remaining steps were the same as in Example 1.

[0045] Comparative Example 2: This comparative example uses propylene oxide instead of the modifier as in Example 1, but the other steps are the same.

[0046] Comparative Example 3: This comparative example uses butylamine instead of aminocage-type silsesquioxane compared to Example 1, with the remaining steps being the same.

[0047] The composite materials obtained in Examples 1-3 and Comparative Examples 1-3 were fabricated according to ASTM D3801 standards with dimensions of 130mm x 13mm x 3.2mm to test the flame retardancy rating and flame extinguishing time. According to ISO 5660-1 standards, the composite materials were fabricated with dimensions of 100mm x 100mm x 50mm to test the total smoke release of the samples. The test results are shown in Table 1 below.

[0048] Table 1 Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Flame retardant rating V0 V0 V0 V0 V1 V0 Flame extinction time s 3.8 3.6 3.2 6.7 11.3 9.2 <![CDATA[Total amount of smoke released m 2 > 0.54 0.55 0.58 0.89 1.36 1.08 As shown in Table 1, this application has excellent flame retardant and smoke-suppressing effects.

[0049] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a highly flame-retardant composite material for 3D printing, characterized in that: Specifically, the steps are as follows: Terephthalic acid, adipic acid, modified monomers, ethylene glycol and molybdenum oxide were mixed evenly, protected by nitrogen gas, and tetrabutyl titanate was added to carry out the reaction, thus obtaining a high flame-retardant composite material for 3D printing.

2. The method for preparing a high flame-retardant composite material for 3D printing according to claim 1, characterized in that: The molar ratio of terephthalic acid, adipic acid, modified monomer, and ethylene glycol is 4:1:0.2:4.7, and the amount of molybdenum oxide used is 3% of the total mass of terephthalic acid, adipic acid, modified monomer, and ethylene glycol.

3. The method for preparing a high flame-retardant composite material for 3D printing according to claim 1, characterized in that: The modified monomer is prepared by the following steps: Step A1: Dissolve pentaerythritol phosphate in dioxane, purge with nitrogen for protection, stir and add epichlorohydrin and boron trifluoride ether, heat to react, cool and add sodium hydroxide solution to carry out the reaction, and obtain the modifier. Step A2: Mix octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water, purge with nitrogen gas, and react to obtain aminopolysiloxane. Step A3: Mix amino polysiloxane, modifier and N,N-dimethylformamide, purge with nitrogen and react to obtain pretreated polysiloxane. Mix pretreated polysiloxane, 4-formylphenylboronic acid, 5A molecular sieve and xylene, purge with nitrogen and react to obtain functionalized polysiloxane. Step A4: Functionalized polysiloxane, aminocage-type silsesquioxane, 5A molecular sieve and N,N-dimethylformamide are mixed, and the mixture is purged with nitrogen for protection and reacted to obtain modified polysiloxane. Modified polysiloxane, allyl alcohol, caster catalyst and N,N-dimethylformamide are mixed, and the mixture is purged with nitrogen for protection and reacted to obtain modified monomer.

4. The method for preparing a high flame-retardant composite material for 3D printing according to claim 3, characterized in that: The ratio of pentaerythritol phosphate, epichlorohydrin, and sodium hydroxide solution used in step A1 is 1 mol: 1 mol: 200 mL.

5. The method for preparing a high flame-retardant composite material for 3D printing according to claim 3, characterized in that: The ratio of octamethylcyclotetrasiloxane, 3-aminopropyldiethoxymethylsilane, tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water used in step A2 is 1.1 mol: 0.1 mol: 1 mol: 1.5 mol: 30 mL.

6. The method for preparing a high flame-retardant composite material for 3D printing according to claim 3, characterized in that: The molar ratio of amino groups and modifiers on the amino polysiloxane described in step A3 is 1:2, and the ratio of hydroxyl groups, 4-formylphenylboronic acid, and 5A molecular sieves on the pretreated polysiloxane is 7.5 mmol:15 mmol:2 g.

7. The method for preparing a high flame-retardant composite material for 3D printing according to claim 3, characterized in that: The ratio of aldehyde group, amino cage-type silsesquioxane and 5A molecular sieve on the functionalized polysiloxane described in step A4 is 20 mmol:20 mmol:5 g, and the molar ratio of modified polysiloxane and allyl alcohol is 1:

2.

8. The method for preparing a high flame-retardant composite material for 3D printing according to claim 3, characterized in that: The aminocage-type silsesquioxane is prepared by the following steps: Methyltrichlorosilane and acetone were mixed, stirred, and deionized water was added. The mixture was heated to obtain the T7 precursor. The T7 precursor, triethylamine, and tetrahydrofuran were mixed, stirred, and aminopropyltriethoxysilane and dibutyltin dilaurate were added. The reaction was carried out, and the pH was adjusted to neutral to obtain an aminocage-type silsesquioxane.

9. The method for preparing a high flame-retardant composite material for 3D printing according to claim 8, characterized in that: The molar ratio of methyltrichlorosilane, acetone and deionized water is 1:10:1.5, and the ratio of the amount of T7 precursor, triethylamine, tetrahydrofuran, aminopropyltriethoxysilane and dibutyltin dilaurate is 1 mol:1.2 mol:5 L:1 mol:0.9 g.

10. A highly flame-retardant composite material for 3D printing, characterized in that: Prepared according to any one of the preparation methods described in claims 1-9.