Material, preparation method thereof and household appliance

Abstract

The invention discloses a material, a preparation method thereof and a household appliance, and belongs to the field of composite materials. The material is a single-molecule core-shell intumescent flame retardant taking hollow glass beads as a core and a covalent organic framework as a shell; the covalent organic framework is obtained by in-situ synthesis of covalent organic framework monomers on the surfaces of the hollow glass beads. The flame retardant is applied to the aspect of wiring outer cover materials of household appliances, solves the problems of short flame-retardant duration and poor flame-retardant effect of the existing flame retardant, and has the characteristics of stable structure, capability of continuously playing a flame-retardant role and good flame-retardant effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of composite materials, and particularly relates to a material, a preparation method thereof and a household appliance. BACKGROUND

[0002] With the continuous issuance of various safety regulations and the continuous improvement of people's safety and environmental protection awareness, it is particularly important to prepare safer and more reliable materials. At present, household appliances have become a necessity for every family, and it is particularly important to improve the material safety of household appliances, thus new requirements for preparing materials with high flame retardance and low smoke volume are put forward.

[0003] Chinese patent CN118290685A discloses a preparation method of a DOPO modified triazine-based covalent organic framework flame retardant and application thereof. The method is to perform surface chemical modification on a triazine-based covalent organic framework material by DOPO, and use the material as an organic filler of epoxy resin to prepare a green halogen-free environmentally friendly flame-retardant epoxy resin by curing. However, the flame retardant still has the problems of short flame-retardant duration and poor flame-retardant effect. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is the short flame-retardant duration and poor flame-retardant effect of the existing flame retardant. The present application provides a material for household appliances, a preparation method thereof and a household appliance, which have the characteristics of structural stability, sustained flame-retardant effect and good flame-retardant effect.

[0005] To solve the technical problem, the technical scheme adopted by the present application is as follows: In one aspect, the present application provides a material, which is a single-molecule core-shell type intumescent flame retardant with hollow glass microspheres as the core and covalent organic frameworks as the shell. The covalent organic frameworks are obtained by in-situ synthesis of covalent organic framework monomers on the surface of the hollow glass microspheres.

[0006] In another aspect, the present application provides a preparation method of the above-mentioned material, which comprises a hollow glass microsphere hydroxylation modification step. The hollow glass microsphere hydroxylation modification step comprises: adding the hollow glass microspheres into a NaOH solution, selectively etching the surface of the hollow glass microspheres with the NaOH solution to generate micro-nanopores and expose silicon hydroxyl groups, and obtaining surface-hydroxylated hollow glass microspheres.

[0007] In some embodiments, the method comprises an aldehyde-terminated hollow glass microsphere covalent organic framework construction step. The constructing step of the aldehyde-terminated hollow glass microsphere covalent organic framework comprises: combining a phosphoric acid derivative with an amine donor containing multiple carbon atoms to form a phosphoric amine compound, reacting the phosphoric amine compound with the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-triformaldehyde, growing the covalent organic framework in situ on the surface of the hollow glass microsphere, and completing the construction of the covalent organic framework.

[0008] In some embodiments, the molar ratio of the aldehyde-terminated hollow glass microsphere to the phosphoric amine compound is 1:5-200; the molar ratio of the phosphoric amine compound to 1,3,5-triazine-2,4,6-triformaldehyde is 1:0.9-1.

[0009] In some embodiments, the reaction of the phosphoric amine compound with the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-triformaldehyde comprises: adding the phosphoric amine compound, the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-triformaldehyde into a glass tube, then adding a mixed solvent, adjusting the pH to 3-6, increasing the reaction temperature to 85-90°C, and reacting at the temperature for 3-5 h. The mixed solvent comprises dioxane, m-trimethylbenzene and acetic acid.

[0010] In some embodiments, the in-situ growth of the covalent organic framework on the surface of the hollow glass microsphere comprises: evacuating the glass tube under a liquid nitrogen cold bath using nitrogen, then sealing the tube opening of the glass tube with a flame spray gun, and placing the glass tube in an oven at 120°C for reaction to obtain the material.

[0011] In some embodiments, the combination of the phosphoric acid derivative with the amine donor containing multiple carbon atoms to form the phosphoric amine compound comprises: separately dissolving the amine donor containing multiple carbon atoms and the phosphoric acid derivative in toluene, and adding the phosphoric acid derivative solution dropwise into the amine donor containing multiple carbon atoms solution for reaction. The molar ratio of the phosphoric acid derivative to the amine donor containing multiple carbon atoms is 1:2, and the reaction temperature is 100-150°C. The amine donor containing multiple carbon atoms is selected from one of hydrazine, p-phenylenediamine and m-phenylenediamine.

[0012] In some embodiments, the method further comprises an amination modification step of the hollow glass microsphere. The amination modification step of the hollow glass microsphere comprises: dispersing the surface hydroxylated hollow glass microsphere in a mixed solution of ethanol and deionized water, and adding an amino-terminated silane coupling agent dropwise into the mixed solution for reaction to obtain the amino-terminated hollow glass microsphere. The amino-terminated silane coupling agent is selected from at least one of KH-550, KH-602, KH-792 or Si-75.

[0013] In some embodiments, an aldehyde modification step of the end-amino hollow glass microsphere is further included. The aldehyde modification step of the end-amino hollow glass microsphere comprises: adding the end-amino hollow glass microsphere and 1,3,5-triazine-2,4,6-tricarboxaldehyde into a mixed solvent, and reacting under the protection of an inert atmosphere to generate end-aldehyde hollow glass microspheres. The end-amino hollow glass microsphere and 1,3,5-triazine-2,4,6-tricarboxaldehyde have a molar ratio of 1:1.01-1.5.

[0014] The application also provides a household appliance, and a wiring cover material of the household appliance comprises the material.

[0015] Compared with the prior art, the application has the following beneficial effects: The application provides a material, which has a hollow glass microsphere as a core and a covalent organic framework as a shell. The strong bonding force between the core and the shell can prevent the covalent organic framework from falling off at high temperatures, so that the flame-retardant effect can be continuously exerted. During the flame-retardant process, the covalent organic framework grafted layer catalyzes the polymer matrix to form carbon at the initial stage of combustion, and the glass microsphere core fills the cracks of the covalent organic framework carbon layer after melting at high temperatures (greater than 600 DEG C), so as to enhance the barrier density. The two components exert the flame-retardant effect in stages, and the flame-retardant effect is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A preparation process flow chart of the material provided by the embodiments of the application is shown. DETAILED DESCRIPTION

[0017] The technical solutions in the specific embodiments of the application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the specific embodiments of the general technical solutions of the application, but not all the embodiments. Based on the general concept of the application, all other embodiments obtained by those skilled in the art fall within the scope of protection of the application.

[0018] A material, which has a hollow glass microsphere as a core.

[0019] The hollow glass microsphere is widely used in polymer fillers due to its light weight, excellent flowability and size stability. In terms of flame retardant filler, the hollow glass microsphere can be uniformly dispersed in the polymer matrix to form a physical barrier, delay the diffusion of heat and oxygen to the matrix, and inhibit the combustion chain reaction. In addition, the internal micro-thin gas layer gives it a low thermal conductivity, reduces the overall heat conduction rate of the material, and delays thermal decomposition, producing a synergistic effect with the flame retardant.

[0020] A material, which has a covalent organic framework as a shell.

[0021] Covalent organic frameworks (COFs) are two-dimensional or three-dimensional crystalline porous polymers composed of discrete pores and highly ordered organic building blocks. Covalent organic frameworks are widely used in gas adsorption, catalysis, separation and optoelectronic devices due to their excellent thermal stability, high specific surface area, porous structure and low density. The rich C / N elements in the structure make it have great potential in the field of flame retardation. As a flame retardant, covalent organic frameworks have excellent thermal stability and can maintain structural integrity during the initial stage of combustion, delaying the thermal decomposition of the matrix. The structure does not contain metal ions, and is resistant to hydrolysis and acid and alkali corrosion. In addition, different monomers can be selected to introduce flame-retardant elements (P, N, etc.) into the covalent organic framework to achieve "molecular-level flame retardant" design. In addition, the microporous structure of the covalent organic framework material can adsorb free radicals generated during combustion, interrupt the chain reaction, and reduce the release of toxic gases, achieving high-efficiency flame retardation.

[0022] A material is a single-molecule core-shell intumescent flame retardant with hollow glass microspheres as the core and covalent organic frameworks as the shell.

[0023] The above-mentioned material combines the low-density characteristics of hollow glass microspheres with the excellent mechanical properties of the core-shell structure, achieving a synergy of lightweight and high strength. The combination of hollow glass microspheres and covalent organic frameworks can delay heat transfer due to the thermal insulation properties of hollow glass microspheres, and the introduction of phosphorus and nitrogen elements in the covalent organic framework can enhance the gas-solid phase flame retardation effect, achieving a synergy of high-efficiency flame retardation and intumescent charring. In addition, the core-shell flame retardant prepared from glass microspheres and covalent organic frameworks can achieve good dispersion in the matrix, achieving isotropy.

[0024] The acid source, carbon source and gas source in the single-molecule intumescent flame retardant are combined in the same molecule through chemical bonds, which has better compatibility with the matrix, surface migration resistance and synchronous reaction of the three elements compared with the blended IFR, and has the advantage of higher flame retardation efficiency.

[0025] A material is a single-molecule core-shell intumescent flame retardant with hollow glass microspheres as the core and covalent organic frameworks as the shell, wherein the covalent organic framework is synthesized in situ on the surface of the hollow glass microspheres by covalent organic framework monomers.

[0026] The above-mentioned material uses hollow glass microspheres as the matrix, introduces amino groups on the surface to form amino-functionalized hollow glass microspheres, and then adds covalent organic framework monomers to further induce the growth of the covalent organic framework shell, generating a novel core-shell flame retardant.

[0027] Compared with blending hollow glass microspheres and covalent organic frameworks as flame retardants, the material with glass microspheres as the core and covalent organic frameworks as the shell has the following advantages: 1) The strong interfacial bonding force can prevent the covalent organic framework from falling off at high temperatures, and continuously play a flame-retardant role; 2) After the surface modification of the hollow glass microsphere, the active sites on the surface of the hollow glass microsphere and the covalent organic framework monomer grow in situ through a covalent bond, realizing molecular-level dispersion, and effectively solving the problem of uneven dispersion of single covalent organic framework flame retardant in the polymer matrix; 3) The covalent organic framework grafted layer catalyzes the polymer matrix to form carbon at the initial stage of combustion, and the hollow glass microsphere core melts at high temperature (>600 DEG C) to fill the cracks of the covalent organic framework carbon layer, enhance the barrier density, and the two play a flame-retardant role in stages; 4) The core-shell structure has isotropy, which can improve the flame retardant performance of the material as a whole, and avoid local defects to improve the mechanical strength of the composite material.

[0028] In terms of material synthesis, it is difficult to directly graft a single molecular covalent organic framework flame retardant to the hollow glass microsphere, because both of them are spherical structures, which is equivalent to "circle outside circle", and this structure is also very unstable, the grafting site is easy to break, the stability is poor, and it cannot play a long-term role. Further reaction with glass microspheres as the core to form a core-shell type flame retardant by building covalent organic framework flame retardant on the outside, the synthesis is easier than the former, and more importantly, the structure is more stable, the mutual contact is more close, and the role is more effective. In the process of flame retardation, the porous structure on the surface of the core-shell structure can also play a role in smoke suppression.

[0029] The present application provides a preparation method of the above-mentioned material, as shown in the following formula: Figure 1 The preparation method comprises a hollow glass microsphere hydroxy modification step.

[0030] In some embodiments, the hollow glass microsphere hydroxy modification step comprises: adding the hollow glass microsphere into a NaOH solution, selectively etching the surface of the hollow glass microsphere with the NaOH solution to generate micro-nano pores and expose silicon hydroxyl groups, and obtaining the surface hydroxylated hollow glass microsphere.

[0031] The surface of the hollow glass microsphere is smooth and lacks active groups, which makes it difficult to combine with the covalent organic framework to form stable chemical bonds. The above technical solution adopts a step-by-step etching-silane coupling composite modification, selectively etches the surface of the glass microsphere with a NaOH solution to generate micro-nano pores and expose silicon hydroxyl groups (Si-OH), and then uses a silane coupling agent for aminization modification, so that the amino group forms a covalent imine bond with the covalent organic framework monomer (such as aldehyde group), thereby ensuring the grafting strength of the single molecular layer.

[0032] In some embodiments, the preparation method comprises a hollow glass microsphere covalent organic framework construction step.

[0033] In some embodiments, the step of constructing the aldehyde-terminated hollow glass microsphere covalent organic framework comprises: combining a phosphoric acid derivative with an amine donor containing multiple carbon atoms to form a phosphoric amine compound, reacting the phosphoric amine compound with the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-trimethyl formaldehyde, growing the covalent organic framework in situ on the surface of the hollow glass microsphere, and completing the construction of the covalent organic framework.

[0034] In order to avoid too many side reactions in the reaction process, the raw materials in the intumescent flame retardant cannot be effectively combined, resulting in a decrease in the flame retardant efficiency. In the above technical solution, the phosphoric acid derivative is first combined with the amine donor containing multiple carbon atoms to form a phosphoric amine compound, which can react with the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-trimethyl formaldehyde to realize the construction of the covalent organic framework, and at the same time, the three sources of carbon source, acid source and gas source are combined, which significantly improves the flame retardant effect. In addition, 1,3,5-triazine-2,4,6-trimethyl formaldehyde has a special triazine structure and can decompose and release N2, NH3 and other non-combustible gases to dilute oxygen, which can be used as a gas source.

[0035] In some embodiments, the phosphoric acid derivative is triphenyl phosphate. Triphenyl phosphate is selected as the carbon source, which can pyrolyze and release acidic substances under heat conditions to catalyze the dehydration of polymers to form carbon; the aromatic skeleton of the covalent organic framework material can be directly converted into a graphitized carbon layer at high temperature, enhancing the strength and continuity of the carbon layer.

[0036] In some embodiments, the molar ratio of the aldehyde-terminated hollow glass microsphere to the phosphoric amine compound is 1:5-200. It can be understood that the molar ratio of the aldehyde-terminated hollow glass microsphere to the phosphoric amine compound can also be 1:20, 1:40, 1:60, 1:80, 1:100, 1:120, 1:140, 1:160, 1:180 and any point value ratio within the range thereof.

[0037] In some embodiments, the molar ratio of the phosphoric amine compound to 1,3,5-triazine-2,4,6-trimethyl formaldehyde is 1:0.9-1.

[0038] In some embodiments, the reaction of the phosphoric amine compound with the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-trimethyl formaldehyde comprises: adding the phosphoric amine compound, the aldehyde-terminated hollow glass microsphere and 1,3,5-triazine-2,4,6-trimethyl formaldehyde into a glass tube, then adding a mixed solvent, adjusting the pH to 3-6, increasing the reaction temperature to 85-90°C, and reacting at this temperature for 3-5 h.

[0039] The organic framework of the covalent organic framework and the inorganic surface of the hollow glass microsphere have a large polarity difference, and direct mixing can easily cause the covalent organic framework to agglomerate or the glass microsphere to break, thereby destroying the integrity of the core-shell structure. The above technical solution realizes the controllable in-situ growth of the covalent organic framework by a low-temperature solvent synthesis method, disperses the surface-modified hollow glass microspheres in a mixed hot solution containing monomers of the covalent organic framework, and then slowly reacts in an inert atmosphere at a low temperature of 85-90°C. The condensation rate is controlled by pH adjustment.

[0040] In some embodiments, the mixed solvent includes dioxane, m-xylene, and acetic acid. In some embodiments, the mixed solvent includes 0.75 mL of dioxane, 0.25 mL of m-xylene, and 1 mL of acetic acid.

[0041] In some embodiments, the in-situ growth of the covalent organic framework on the surface of the hollow glass microsphere includes: evacuating the glass tube under a nitrogen gas cold bath, then sealing the tube opening of the glass tube with a flame spray gun, and then placing the glass tube in an oven at 120°C for reaction to obtain a flame retardant.

[0042] The in-situ growth of the covalent organic framework is difficult to control, and uneven growth can cause uneven shell thickness. The above technical solution strengthens the stability of the core-shell structure, and enhances the crystallinity and interface bonding strength of the covalent organic framework through auxiliary thermal annealing (120°C, N2 protection).

[0043] In some embodiments, combining the phosphoric acid derivative with the amine donor containing multiple carbon atoms to form an amine phosphate compound includes: dissolving the amine donor containing multiple carbon atoms and the phosphoric acid derivative in toluene respectively, and adding the phosphoric acid derivative solution to the amine donor containing multiple carbon atoms solution for reaction.

[0044] In some embodiments, the molar ratio of the phosphoric acid derivative to the amine donor containing multiple carbon atoms is 1:2, and the reaction temperature is 100-150°C. It can be understood that the reaction temperature can also be 110°C, 120°C, 130°C, 140°C, and any point value within the range thereof.

[0045] In some embodiments, the amine donor containing multiple carbon atoms is selected from one of hydrazine, p-phenylenediamine, and m-phenylenediamine.

[0046] In some embodiments, the method further includes an amination modification step of the hollow glass microsphere.

[0047] In some embodiments, the amination modification step of the hollow glass microsphere includes: dispersing the surface-hydroxylated hollow glass microspheres in a mixed solution of ethanol and deionized water, and adding an amino-terminated silane coupling agent dropwise to obtain amino-terminated hollow glass microspheres.

[0048] In some embodiments, the amino-terminated silane coupling agent is selected from at least one of KH-550, KH-602, KH-792, or Si-75.

[0049] In some embodiments, the method further comprises an aldehyde-modification step of the amino-terminated hollow glass beads.

[0050] In some embodiments, the aldehyde-modification step of the amino-terminated hollow glass beads comprises: adding the amino-terminated hollow glass beads and 1,3,5-triazine-2,4,6-tricarboxaldehyde into a mixed solvent, and reacting under an inert atmosphere to generate aldehyde-terminated hollow glass beads.

[0051] In some embodiments, the molar ratio of the amino-terminated hollow glass beads to 1,3,5-triazine-2,4,6-tricarboxaldehyde is 1:1.01-1.5. It can be understood that the molar ratio of the amino-terminated hollow glass beads to 1,3,5-triazine-2,4,6-tricarboxaldehyde can also be 1:1.1, 1:1.2, 1:1.3, 1:1.4, and any point value ratio within the range thereof.

[0052] In some embodiments, the method for preparing the material specifically comprises: The hollow glass beads (HGB) are added to a NaOH solution, and the mixture is placed in a round-bottom flask and stirred in an 80°C oil bath for 2 h. The filtered hollow glass beads are washed with deionized water until neutral, and dried in an oven to obtain hydroxylated glass beads (HGB-OH); The HGB-OH is weighed and dispersed in a mixed solution of a certain amount of ethanol and deionized water. Then, the amino-terminated silane coupling agent is slowly added to the above system, and the mixed solution is stirred at 75°C for 24 h. Finally, the glass microspheres modified by the amino-terminated silane coupling agent (HGB-NH2) are prepared, and the suspension is centrifuged, washed with ethanol and deionized water, and then the product is placed in a 100°C oven and dried; The HGB-NH2 and 1,3,5-triazine-2,4,6-tricarboxaldehyde are added to a high-temperature-resistant glass tube, and then a mixed solvent of 0.75 mL dioxane, 0.25 mL m-trimethylbenzene, and 1 mL acetic acid is added. The glass tube is evacuated three times using nitrogen gas under a liquid nitrogen cold bath, and then the glass tube is sealed with a flame spray gun, keeping the length of the glass tube at about 10 cm. The glass tube is placed in a 120°C oven for three days to obtain the product. After cooling to room temperature, the solvent is removed, and the solid product HGB-CHO is obtained by washing with a selective solvent selected from one of tetrahydrofuran, acetone, and n-hexane. The amine donor containing multiple carbon atoms is first added into a four-necked flask equipped with a stirring device, a constant pressure dropping funnel, a thermometer and a reflux condenser, then toluene is added, heated to complete dissolution, then toluene is added to the phosphoric acid triphenyl ester to dissolve it, and the phosphoric acid triphenyl ester solution is added dropwise into the four-necked flask through the constant pressure dropping funnel to carry out the reaction (the molar ratio of phosphoric acid triphenyl ester to the substance containing the amine donor with multiple carbon atoms is 1:2), the reaction temperature is 100-150 DEG C, the stirring speed is 500 r / min, and the reaction is carried out for 8 hours, then a small amount of methanol or water is added after the solution is cooled to room temperature to precipitate the product and carry out filtration treatment, and the product is dried to obtain the ammonium phosphate compound; The amine phosphate compound, HGB-CHO and 1,3,5-triazine-2,4,6-triformaldehyde are added into a high-temperature-resistant glass tube, then a mixed solvent 0.75 mL dioxane, 0.25 mL m-trimethylbenzene and 1 mL acetic acid are added, the pH is adjusted to 3-6, the reaction temperature is increased to 85-90 DEG C, and the product is obtained after reaction at the temperature for 3-5 hours. The glass tube is evacuated three times under a liquid nitrogen cold bath using nitrogen, then the glass tube is sealed with a flame gun, the length of the glass tube is kept at about 10 cm, the glass tube is placed in an oven at 120 DEG C for three days to obtain the product, the solvent is removed after cooling to room temperature, and the product is washed with a selective solvent to obtain the core-shell covalent organic framework finally.

[0053] The application provides a household appliance, and a wiring cover material of the household appliance comprises the material in the technical solution.

[0054] The material is based on hollow glass microbeads, and after modification by amination and aldehyde group modification, the hollow glass microbeads are reacted with covalent organic framework monomers to obtain a single-molecule core-shell type intumescent flame retardant with the hollow glass microbeads as the core and the covalent organic framework as the shell. In the preparation process, triazine substances, phosphoric acid derivatives and amino donors with multiple carbon atoms are used as raw materials to prepare a single-molecule intumescent flame retardant. The flame retardant has the advantages of stable structure, rapid charring speed, easy dehydration to delay combustion, low combustion smoke, high flame retardant efficiency and uniform dispersion in the matrix, and when used in a household appliance wiring cover material, the flame retardant is beneficial to improving the flame retardancy and safety of the material.

[0055] To more clearly and specifically introduce the material, the preparation method and the household appliance provided in the embodiments of the application, the following will be described in combination with specific embodiments.

[0056] Embodiment 1 Raw material composition: KH-550 is used as an end-amino silane coupling agent, n （HGB-NH2） : n （1,3,5-三嗪-2,4,6-三甲醛） =1:1.01, the selective solvent is tetrahydrofuran, the amine donor containing multiple carbon atoms is p-phenylenediamine, n （HGB-CHO） : n （1,3,5-三嗪-2,4,6-三甲醛）1:150, n （磷酸铵类化合物） : n （1,3,5-三嗪-2,4,6-三甲醛） 1:0.9.

[0057] Preparation step: (1) Hollow glass beads (HGB) were added to a NaOH solution, and the mixture was placed in a round-bottom flask and stirred in an 80°C oil bath for 2 h. The filtered hollow glass beads were washed with deionized water until neutral and dried in an oven to obtain hydroxylated glass beads (HGB-OH).

[0058] (2) HGB-OH was weighed and dispersed in a mixed solution of a certain amount of ethanol and deionized water, then an amino-terminated silane coupling agent was slowly added dropwise to the above system, and the mixed solution was stirred at 75°C for 24 h. Finally, glass microspheres modified by an amino-terminated silane coupling agent (HGB-NH2) were prepared, and the suspension was centrifuged, washed with ethanol and deionized water, and then the product was placed in a 100°C oven and dried.

[0059] (3) HGB-NH2 and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added to a high-temperature-resistant glass tube, then mixed solvents 0.75 mL dioxane, 0.25 mL m-xylene and 1 mL acetic acid were added, the glass tube was evacuated three times using nitrogen gas under liquid nitrogen cooling, then the glass tube was sealed with a flame gun, the length of the glass tube was maintained at about 10 cm, and the glass tube was placed in a 120°C oven for three days to obtain the product. After cooling to room temperature, the solvent was removed and washed with a selective solvent, and the solid product HGB-CHO was obtained after drying.

[0060] (4) First, an amine donor containing multiple carbon atoms was added to a four-necked flask equipped with a stirring device, a constant-pressure dropping funnel, a thermometer, and a reflux condenser, then toluene was added, heated to complete dissolution, then toluene was added to the phosphoric acid triphenyl ester to dissolve it, and the phosphoric acid triphenyl ester solution was added dropwise to the four-necked flask through the constant-pressure dropping funnel for reaction (the molar ratio of phosphoric acid triphenyl ester to amine donor containing multiple carbon atoms was 1:2), the reaction temperature was 100°C, and the stirring speed was 500 r / min. The reaction was carried out for 8 hours, then a small amount of methanol or water was added to the solution after it cooled to room temperature to precipitate the product and perform suction filtration treatment, and the ammonium phosphate compound was obtained after drying.

[0061] (5) The ammonium phosphate compound, HGB-CHO, and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added to a high-temperature-resistant glass tube, then mixed solvents 0.75 mL dioxane, 0.25 mL m-xylene and 1 mL acetic acid were added, the pH was adjusted to 3, the reaction temperature was increased to 85°C, and the reaction was carried out at this temperature for 3 h to obtain the product.

[0062] (6) The glass tube is evacuated three times using nitrogen gas under a liquid nitrogen cold bath, then the glass tube opening is sealed with a flame spray gun, the length of the glass tube is maintained at about 10 cm, the glass tube is placed in an oven at 120°C for three days to obtain the product, after cooling to room temperature, the solvent is removed, and the selective solvent is washed, and finally the core-shell covalent organic framework is obtained.

[0063] Example 2 Raw material composition: KH-602 as an amino-terminated silane coupling agent, n （HGB-NH2） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:1.2, the selective solvent is tetrahydrofuran, the amine donor containing multiple carbon atoms is p-phenylenediamine, n （HGB-CHO） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:200, n （磷酸铵类化合物） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:0.9.

[0064] Preparation steps: (1) Hollow glass beads (HGB) are added to a NaOH solution, the mixture is placed in a round-bottom flask and stirred in an 80°C oil bath for 2 h, the filtered hollow glass beads are washed with deionized water until neutral, and dried in an oven to obtain hydroxylated glass microspheres (HGB-OH).

[0065] (2) HGB-OH is weighed and dispersed in a certain amount of a mixed solution of ethanol and deionized water, then an amino-terminated silane coupling agent is slowly added dropwise to the above system, the mixed solution is stirred at 75°C for 24 h, finally, the glass microspheres modified by the amino-terminated silane coupling agent (HGB-NH2) are prepared and the suspension is centrifuged, washed with ethanol and deionized water, and the product is placed in a 100°C oven and dried.

[0066] (3) HGB-NH2 and 1,3,5-triazine-2,4,6-tricarboxaldehyde are added to a high-temperature-resistant glass tube, then 0.75 mL of dioxane, 0.25 mL of m-trimethylbenzene, and 1 mL of acetic acid are added, the glass tube is evacuated three times using nitrogen gas under a liquid nitrogen cold bath, then the glass tube opening is sealed with a flame spray gun, the length of the glass tube is maintained at about 10 cm, the glass tube is placed in an oven at 120°C for three days to obtain the product, after cooling to room temperature, the solvent is removed, and the selective solvent is washed, and the solid product HGB-CHO is obtained after drying.

[0067] (4) First, the amine donor containing multiple carbon atoms is added to a four-necked flask equipped with a stirring device, a constant pressure dropping funnel, a thermometer, and a reflux condenser, and then toluene is added and heated to complete dissolution. Then, toluene is added to the phosphoric acid triphenyl ester to dissolve it, and the phosphoric acid triphenyl ester solution is added dropwise to the four-necked flask through the constant pressure dropping funnel to react (the molar ratio of phosphoric acid triphenyl ester to the amine donor containing multiple carbon atoms is 1:2). The reaction temperature is 150°C, and the stirring speed is 500 r / min. The reaction is carried out for 8 hours. After the solution is cooled to room temperature, a small amount of methanol or water is added to precipitate the product and perform suction filtration treatment. After drying, the ammonium phosphate compound is obtained.

[0068] (5) The phosphoric acid amine compound, HGB-CHO, and 1,3,5-triazine-2,4,6-triformaldehyde are added to a high-temperature-resistant glass tube, and then a mixed solvent of 0.75 mL dioxane, 0.25 mL m-trimethylbenzene, and 1 mL acetic acid is added to adjust the pH to 6. The reaction temperature is raised to 90°C, and the reaction is carried out at this temperature for 5 hours to obtain the product.

[0069] (6) The glass tube is evacuated three times using nitrogen in a liquid nitrogen cold bath, and then the glass tube is sealed with a flame gun to maintain a length of about 10 cm. The glass tube is placed in a 120°C oven for three days to obtain the product. After cooling to room temperature, the solvent is removed, and the product is washed with a selective solvent to obtain a core-shell covalent organic framework.

[0070] Example 3 Raw material composition: KH-792 as an amino-terminated silane coupling agent, n （HGB-NH2） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:1.3, the selective solvent is tetrahydrofuran, the amine donor containing multiple carbon atoms is m-phenylenediamine, n （HGB-CHO） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:100, n （磷酸铵类化合物） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:0.95.

[0071] Preparation steps: (1) Hollow glass beads (HGB) are added to a NaOH solution, and the mixture is placed in a round-bottom flask and stirred in an 80°C oil bath for 2 hours. The filtered hollow glass beads are washed with deionized water until neutral and dried in an oven to obtain surface-hydroxylated glass beads (HGB-OH).

[0072] (2) HGB-OH was weighed and dispersed in a mixed solution of a certain amount of ethanol and deionized water, then an amino-terminated silane coupling agent was slowly added dropwise into the above system, the mixed solution was stirred at 75°C for 24 h, finally, the glass microspheres modified by the amino-terminated silane coupling agent (HGB-NH2) were prepared and the suspension was centrifuged, washed with ethanol and deionized water, and then the product was placed in an oven at 100°C and dried.

[0073] (3) HGB-NH2 and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added to a high-temperature-resistant glass tube, then a mixed solvent of 0.75 mL dioxane, 0.25 mL m-xylene and 1 mL acetic acid was added, the glass tube was evacuated three times under liquid nitrogen cooling using nitrogen gas, then the glass tube was sealed with a flame gun, the length of the glass tube was kept at about 10 cm, the glass tube was placed in an oven at 120°C for three days to obtain the product, after cooling to room temperature, the solvent was removed, and the product was washed with a selective solvent to obtain a solid product HGB-CHO.

[0074] (4) An amine donor containing multiple carbon atoms was first added to a four-necked flask equipped with a stirring device, a constant-pressure dropping funnel, a thermometer and a reflux condenser, then toluene was added and heated to complete dissolution, then toluene was added to the phosphoric acid triphenyl ester to dissolve it, and the phosphoric acid triphenyl ester solution was added dropwise into the four-necked flask through the constant-pressure dropping funnel for reaction (the molar ratio of phosphoric acid triphenyl ester to amine donor containing multiple carbon atoms was 1:2), the reaction temperature was 120°C, and the stirring speed was 500 r / min, the reaction was carried out for 8 hours, then a small amount of methanol or water was added to the solution after it was cooled to room temperature to precipitate the product and perform suction filtration treatment, and the product was dried to obtain an ammonium phosphate compound.

[0075] (5) The ammonium phosphate compound, HGB-CHO and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added to a high-temperature-resistant glass tube, then a mixed solvent of 0.75 mL dioxane, 0.25 mL m-xylene and 1 mL acetic acid was added, the pH was adjusted to 4, the reaction temperature was increased to 87°C, and the reaction was carried out at this temperature for 4 h to obtain the product.

[0076] (6) The glass tube was evacuated three times under liquid nitrogen cooling using nitrogen gas, then the glass tube was sealed with a flame gun, the length of the glass tube was kept at about 10 cm, the glass tube was placed in an oven at 120°C for three days to obtain the product, after cooling to room temperature, the solvent was removed, and the product was washed with a selective solvent, and finally a core-shell covalent organic framework was obtained.

[0077] Example 4 Raw material composition: Si-75 as an amino-terminated silane coupling agent, n （HGB-NH2） : n （1,3,5-三嗪-2,4,6-三甲醛）1:1.5, the selective solvent is n-hexane, the poly-carbon atom containing amine donor is hydrazine, and n （HGB-CHO） : n （1,3,5-三嗪-2,4,6-三甲醛） 1:50, n （磷酸铵类化合物） : n （1,3,5-三嗪-2,4,6-三甲醛） 1:1.

[0078] Preparation steps: (1) Hollow glass beads (HGB) were added to a NaOH solution, and the mixture was placed in a round-bottom flask and stirred in an 80°C oil bath for 2 h. The filtered hollow glass beads were washed with deionized water until neutral and dried in an oven to obtain hydroxylated glass beads (HGB-OH).

[0079] (2) HGB-OH was weighed and dispersed in a mixed solution of a certain amount of ethanol and deionized water, then an amino-terminated silane coupling agent was slowly added dropwise to the above system, and the mixed solution was stirred at 75°C for 24 h. Finally, the glass microspheres modified by the amino-terminated silane coupling agent (HGB-NH2) were prepared, and the suspension was centrifuged, washed with ethanol and deionized water, and then the product was placed in a 100°C oven and dried.

[0080] (3) HGB-NH2 and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added to a high-temperature-resistant glass tube, then 0.75 mL of dioxane, 0.25 mL of m-xylene, and 1 mL of acetic acid were added, the glass tube was evacuated three times using nitrogen gas under a liquid nitrogen cold bath, then the glass tube was sealed with a flame gun, the length of the glass tube was maintained at about 10 cm, and the glass tube was placed in a 120°C oven for three days to obtain the product. After cooling to room temperature, the solvent was removed and washed with a selective solvent, and the solid product HGB-CHO was obtained after drying.

[0081] (4) The poly-carbon atom containing amine donor was first added to a four-necked flask equipped with a stirring device, a constant-pressure dropping funnel, a thermometer, and a reflux condenser, then toluene was added, heated to complete dissolution, then toluene was added to the phosphoric acid triphenyl ester to dissolve it, and the phosphoric acid triphenyl ester solution was added dropwise to the four-necked flask through the constant-pressure dropping funnel for reaction (the molar ratio of phosphoric acid triphenyl ester to poly-carbon atom containing amine donor was 1:2), the reaction temperature was 100°C, and the stirring speed was 500 r / min. The reaction was carried out for 8 hours, then a small amount of methanol or water was added after the solution was cooled to room temperature to precipitate the product and perform suction filtration treatment, and the ammonium phosphate compound was obtained after drying.

[0082] (5) The phosphoramidite compound, HGB-CHO and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added into a high-temperature-resistant glass tube, then a mixed solvent of 0.75 mL dioxane, 0.25 mL m-xylene and 1 mL acetic acid was added, the pH was adjusted to 3, the reaction temperature was increased to 85°C, and the reaction was carried out at this temperature for 3 h to obtain the product.

[0083] (6) The glass tube was evacuated three times under liquid nitrogen cooling using nitrogen, then the glass tube was sealed with a flame spray gun, the length of the glass tube was kept at about 10 cm, and the glass tube was placed in an oven at 120°C for three days to obtain the product. After cooling to room temperature, the solvent was removed, and the selective solvent was washed, and finally the core-shell covalent organic framework was obtained.

[0084] Comparative Example 1 Raw material composition: KH-550 as an amino-terminated silane coupling agent, n （HGB-NH2） : n （1,3,5-三嗪-2,4,6-三甲醛） = 1:1.01, and the selective solvent was tetrahydrofuran.

[0085] Preparation steps: (1) Hollow glass beads (HGB) were added to a NaOH solution, and the mixture was placed in a round-bottom flask and stirred in an 80°C oil bath for 2 h. The filtered hollow glass beads were washed with deionized water until neutral, and then dried in an oven to obtain hydroxylated glass microspheres (HGB-OH).

[0086] (2) HGB-OH was weighed and dispersed in a mixed solution of a certain amount of ethanol and deionized water, then an amino-terminated silane coupling agent was slowly added to the above system, and the mixed solution was stirred at 75°C for 24 h. Finally, the glass microspheres modified by the amino-terminated silane coupling agent (HGB-NH2) were prepared, and the suspension was centrifuged, washed with ethanol and deionized water, and then the product was placed in a 100°C oven and dried.

[0087] (3) HGB-NH2 and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added into a high-temperature-resistant glass tube, then a mixed solvent of 0.75 mL dioxane, 0.25 mL m-xylene and 1 mL acetic acid was added, the glass tube was evacuated three times under liquid nitrogen cooling using nitrogen, then the glass tube was sealed with a flame spray gun, the length of the glass tube was kept at about 10 cm, and the glass tube was placed in an oven at 120°C for three days to obtain the product. After cooling to room temperature, the solvent was removed, and the selective solvent was washed, and finally the core-shell covalent organic framework was obtained.

[0088] Comparative Example 2 The hollow glass microspheres were mixed with a monomolecular covalent organic framework flame retardant as a flame retardant.

[0089] Comparative Example 3 A single-molecule expanded alkyl phosphinate salt flame retardant was used as an additive as a comparative sample.

[0090] The raw material compositions of the examples and some comparative examples are shown in Table 1.

[0091] Table 1 Raw material composition

[0092] Test sample preparation (1) The samples obtained in Examples 1-4, the comparative samples obtained in Comparative Examples 1-3, or a commercially available flame retardant (ammonium polyphosphate) were mixed with the modified raw material (ABS or PS or PP) in weight percent according to Tables 2-3 in a high-speed mixer, and the mixture was fed into an extruder. The mixture was melt-mixed on a screw extruder, extruded through the extruder, cooled in a water tank, and cut into particles by a cutting machine for use. The specific process conditions are shown below: The stirring speed of the high-speed mixer was 2000 r / min, and the stirring time was 10 min.

[0093] Extrusion granulation process: The temperature control of the screw extruder for ABS material was 230±10℃, 240±10℃, 250±10℃, 240±10℃, 240±10℃, 225±10℃, 210±10℃, 200±10℃; the die temperature control was 240±10℃; the vacuum degree was ≤0.06 MPa; and the water tank temperature was ≤50℃. The temperature control of the screw extruder for PS material was 210±10℃, 220±10℃, 225±10℃, 210±10℃, 210±10℃, 200±10℃, 200±10℃, 195±10℃; the die temperature control was 220±10℃; the vacuum degree was ≤0.06 MPa; and the water tank temperature was ≤50℃. The temperature control of the screw extruder for PP material was 175±10℃, 180±10℃, 185±10℃, 185±10℃, 190±10℃, 190±10℃, 190±10℃, 190±10℃; the die temperature control was 190±10℃; the vacuum degree was ≤0.06 MPa; and the water tank temperature was ≤50℃.

[0094] (2) The flame-retardant modified particles were injection molded to obtain corresponding test bars.

[0095] Table 2 ABS material group

[0096] Table 3 PS and PP groups

[0097] Performance test The above obtained sample was subjected to performance test, and the standards of each test item were as follows: (1) tensile breaking stress: GB / T 1040.1 2018; (2) oxygen index: GB / T 2406 2009; (3) vertical burning grade: GB / T 2408 2008; (4) smoke density: GB / T 8627 2007; The test results are shown in Tables 4-5.

[0098] Table 4 Test results of ABS material group

[0099] Table 5 Test results of PS and PP material group

[0100] Experiments prove that the novel flame retardant provided by the application can effectively improve the flame retardant performance of the material, and has low combustion smoke volume, in addition, since the flame retardant is modified on the basis of hollow glass microspheres, compared with traditional flame retardants, it can impart flame retardant performance to the material without increasing the weight of the polymer, which meets the current lightweight development trend.

Claims

1. A material, characterized in that, The material is a single-molecule core-shell type intumescent flame retardant with hollow glass microspheres as the core and covalent organic frameworks as the shell; the covalent organic frameworks are obtained by in-situ synthesis of covalent organic framework monomers on the surface of the hollow glass microspheres.

2. The method of claim 1, wherein the material is prepared by a method comprising: The step of hydroxyl modification of the hollow glass microspheres is included; The step of hydroxyl modification of the hollow glass microspheres includes: adding the hollow glass microspheres into a NaOH solution, selectively etching the surface of the hollow glass microspheres by using the NaOH solution, generating micro-nanopores and exposing silicon hydroxyl groups, and obtaining surface-hydroxylized hollow glass microspheres.

3. The method of claim 2, wherein the material is prepared by a method comprising: The step of constructing covalent organic frameworks on the surface of the aldehyde-terminated hollow glass microspheres is included; The step of constructing covalent organic frameworks on the surface of the aldehyde-terminated hollow glass microspheres includes: combining a phosphoric acid derivative with an amine donor containing multiple carbon atoms to form a phosphoric amine compound, and reacting the phosphoric amine compound with aldehyde-terminated hollow glass microspheres and 1,3,5-triazine-2,4,6-triformaldehyde, so that the covalent organic frameworks grow in-situ on the surface of the hollow glass microspheres, and the construction of the covalent organic frameworks is completed.

4. The method of claim 3, wherein the material is prepared by a method comprising: The molar ratio of the aldehyde-terminated hollow glass microspheres to the phosphoric amine compound is 1:5-200; and the molar ratio of the phosphoric amine compound to the 1,3,5-triazine-2,4,6-triformaldehyde is 1:0.9-1.

5. The method of claim 3, wherein the material is prepared by a method comprising: The reaction of the phosphoric amine compound with aldehyde-terminated hollow glass microspheres and 1,3,5-triazine-2,4,6-triformaldehyde includes: adding the phosphoric amine compound, the aldehyde-terminated hollow glass microspheres, and the 1,3,5-triazine-2,4,6-triformaldehyde into a glass tube, then adding a mixed solvent, adjusting the pH to 3-6, increasing the reaction temperature to 85-90℃, and reacting at the temperature for 3-5 h. The mixed solvent includes dioxane, m-xylene, and acetic acid.

6. The method of claim 5, wherein the material is prepared by a method comprising: The in-situ growth of the covalent organic frameworks on the surface of the hollow glass microspheres includes: evacuating the glass tube under a nitrogen gas cold bath, then sealing the tube opening of the glass tube with a flame spray gun, and placing the glass tube in an oven at 120℃ for reaction, to obtain the material.

7. The method of claim 3, wherein the material is prepared by a method comprising: The combination of the phosphoric acid derivative with the amine donor containing multiple carbon atoms to form the phosphoric amine compound includes: separately dissolving the amine donor containing multiple carbon atoms and the phosphoric acid derivative in toluene, and dropping the phosphoric acid derivative solution into the amine donor containing multiple carbon atoms solution for reaction; The molar ratio of the phosphoric acid derivative to the amine donor containing multiple carbon atoms is 1:2, and the reaction temperature is 100-150℃. The amine donor containing multiple carbon atoms is selected from one of hydrazine, p-phenylenediamine, and m-phenylenediamine.

8. The method of claim 2, wherein the material is prepared by a method comprising: The step of aminating modification of the hollow glass microspheres is also included; The step of aminating modification of the hollow glass microspheres includes: dispersing the surface-hydroxylized hollow glass microspheres in a mixed solution of ethanol and deionized water, and dropping an amino-terminated silane coupling agent into the solution for reaction to obtain amino-terminated hollow glass microspheres; The amino-terminated silane coupling agent is selected from at least one of KH-550, KH-602, KH-792, or Si-75.

9. The method of claim 8, wherein the material is prepared by a method comprising: The step of aldehyde-modification of the amino-terminated hollow glass microspheres is also included; The aldehyde group modification step of the end-amino hollow glass microsphere includes: adding the end-amino hollow glass microsphere and 1,3,5-triazine-2,4,6-tricarboxaldehyde into a mixed solvent, and reacting under the protection of an inert atmosphere to generate an end-aldehyde group hollow glass microsphere. The end-amino hollow glass microsphere and the 1,3,5-triazine-2,4,6-tricarboxaldehyde have a molar ratio of 1:1.01-1.

5.

10. An electric home appliance characterized by comprising: The wiring cover material of the household appliance comprises the material of claim 1.

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