Modified vermiculite charring agent, preparation method and application thereof, flame-retardant polyurethane material and preparation method thereof

Abstract

The invention discloses a modified vermiculite charring agent, a preparation method and application thereof, a flame-retardant polyurethane material and a preparation method thereof, and relates to the technical field of flame-retardant materials. The modified vermiculite charring agent comprises vermiculite, a silane coupling agent and organophosphorus ester which are arranged in sequence, the silane coupling agent comprises an amino silane coupling agent, the organophosphorus ester contains phosphate ester groups and non-esterified hydroxyl groups, and the silane coupling agent is connected with the vermiculite and the organophosphorus ester through chemical bonds. Silanol generated by hydrolysis of an alkoxy group of the silane coupling agent and hydroxyl of vermiculite are subjected to a condensation reaction to form a chemical bond, so that the silane coupling agent is connected with the vermiculite; the amino group of the silane coupling agent reacts with the phosphate group of the organophosphorus ester to form a chemical bond, so that the organophosphorus ester is connected to the silane coupling agent. The loading capacity of organophosphate on the surface of vermiculite can be improved, the flame retardant efficiency of the modified vermiculite charring agent is remarkably improved, and the problems that polyurethane is low in charring rate and poor in flame retardant property are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant materials, in particular to a modified vermiculite charring agent and a preparation method and application thereof, a flame retardant polyurethane material and a preparation method thereof. Background Art

[0002] During the polyurethane synthesis process, the ratio of polyols, isocyanates, and chain extenders can be adjusted to create polyurethane materials with varying properties to meet the needs of diverse applications such as elastomers, foams, and adhesives. However, like most polymers, polyurethane readily burns in air, generating large amounts of molten droplets, heat, and toxic and corrosive gases, posing a potential fire hazard. Therefore, flame-retardant modification of polyurethane is of great industrial significance.

[0003] The liquid oxygen-containing phosphoric acid released by the thermal decomposition of organophosphorus flame retardants can cover the surface of the substrate and promote the dehydration and esterification of the substrate to form a molten substance. The protective carbon layer formed after the substance solidifies on the surface of the unburned substrate has the functions of heat insulation, oxygen isolation, delaying the spread of flames, and adsorbing toxic smoke. However, most organophosphorus flame retardants are liquid phosphorus, which has defects such as poor thermal stability and high volatility. They easily react with oxygen in high temperature environments and enter the air, causing the phosphorus content in the flame retardant material to decrease. Therefore, the actual flame retardant efficiency of the phosphorus-containing compound in the polymer matrix is ​​affected, and the carbonization effect of the material and the quality of the carbon layer also decrease. It is easily oxidized and cracked under the impact of heat flow and flame, and cannot significantly improve the fire safety of the material. Therefore, in order to further increase the actual phosphorus content in the flame retardant material, and then improve the coverage area and quality of the carbonization of the material, it is the key to improving the flame retardant effect of the composite material.

[0004] To address this issue, researchers usually use microencapsulation technology to improve the thermal stability of organophosphorus flame retardants and their actual flame retardant efficiency in the matrix. Chinese invention patent CN113462027A uses melamine resin to coat flame retardants including ammonium polyphosphate and DOPO. The resulting composite flame retardant greatly improves the flame retardant properties of polyester and reduces smoke release. However, in the absence of a carbonizing agent, the carbonizing effect of a single-component microencapsulated modified organophosphorus flame retardant on the matrix is ​​still insufficient. In addition, the resin material used as the shell is prone to release toxic gases during combustion, posing a threat to human health and the ecological environment. Therefore, developing a green, environmentally friendly, and highly efficient carbonizing phosphorus-containing flame retardant system and using it to improve the flame retardant properties of polyurethane materials is one of the research focuses in the field of flame retardancy. Summary of the Invention

[0005] The main purpose of the present invention is to propose a modified vermiculite charring agent and a preparation method and application of a flame retardant polyurethane material, aiming to solve the problems of low charring rate and poor flame retardancy of existing polyurethane materials.

[0006] To achieve the above objectives, the present invention proposes a modified vermiculite charring agent, comprising vermiculite, a silane coupling agent and an organic phosphate arranged in sequence, wherein the silane coupling agent comprises an aminosilane coupling agent, the organic phosphate contains a phosphate group and an unesterified hydroxyl group, and the silane coupling agent is connected to the vermiculite and the organic phosphate respectively through chemical bonds.

[0007] In one embodiment, the silane coupling agent includes any one of N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane; and / or,

[0008] The organic phosphate includes any one of 2-ethylhexyl phosphate, mono(2-methylpropyl) phosphate, and isooctyl phosphate.

[0009] The present invention provides a method for preparing the modified vermiculite carbonizing agent as described in the above technical solution, comprising the following steps:

[0010] Mixing a silane coupling agent, ethanol, and deionized water to obtain a silane coupling agent solution, mixing vermiculite with the silane coupling agent solution and adjusting the pH to alkaline, performing a first condensation reaction to obtain a first suspension, performing solid-liquid separation on the first suspension to obtain a first solid, washing and drying the first solid to obtain silane coupling agent-modified vermiculite;

[0011] An organic phosphate ester and anhydrous ethanol are mixed to obtain an organic phosphate ester solution, the silane coupling agent modified vermiculite and the organic phosphate ester solution are mixed and heated to obtain a second suspension, the second suspension is subjected to solid-liquid separation to obtain a second solid, the second solid is washed and dried to obtain a modified vermiculite carbonizing agent.

[0012] In one embodiment, the mass ratio of the vermiculite, deionized water, silane coupling agent and anhydrous ethanol is 15:30:(1.5-5):(150-300).

[0013] In one embodiment, the mass ratio of the silane coupling agent modified vermiculite to the organic phosphate is 1:(1-4).

[0014] In one embodiment, the heating temperature is 90° C. to 120° C.; and / or,

[0015] The heating time is 6 hours to 12 hours.

[0016] The present invention proposes an application of a modified vermiculite high-efficiency charring agent in the preparation of a flame-retardant polyurethane material. The modified vermiculite high-efficiency charring agent includes the modified vermiculite charring agent described in the aforementioned technical solution, or includes a modified vermiculite charring agent prepared according to the preparation method of the modified vermiculite charring agent described in the aforementioned technical solution.

[0017] The present invention provides a method for preparing a flame retardant polyurethane material, comprising the following steps:

[0018] Dehydrating the polyester polyol and the polyether polyol to obtain dehydrated polyester polyol and dehydrated polyether polyol;

[0019] Mixing a modified vermiculite carbonizing agent, dehydrated polyester polyol, dehydrated polyether polyol and a metal catalyst to obtain a reaction base material;

[0020] Adding isophorone diisocyanate prepolymer to the reaction base to carry out a second condensation reaction to obtain a flame retardant polyurethane material; wherein:

[0021] The modified vermiculite carbonizing agent is the modified vermiculite carbonizing agent described in the aforementioned technical solution, or is a modified vermiculite carbonizing agent prepared by the preparation method of the modified vermiculite carbonizing agent described in the aforementioned technical solution.

[0022] In one embodiment, the number average molecular weight of the polyester polyol is 1000 to 4000; and / or,

[0023] The polyether polyol includes polyethylene glycol 400; and / or,

[0024] The mass ratio of the modified vermiculite carbonizing agent, dehydrated polyester polyol, dehydrated polyether polyol and metal catalyst is 1: (6-13): (0.6-1.3): (0.04-0.08); and / or,

[0025] The mass ratio of the modified vermiculite carbonizing agent to the isophorone diisocyanate prepolymer is 1:(8-13); and / or,

[0026] The temperature of the second condensation reaction is 60°C to 90°C; and / or,

[0027] The second condensation reaction time is 3.5h to 6.5h.

[0028] The present invention provides a flame retardant polyurethane material, which is prepared according to the preparation method of the flame retardant polyurethane material described in the above technical solution.

[0029] The beneficial effects of the technical solution of the present invention are as follows:

[0030] The technical solution of the present invention provides a modified vermiculite carbonizing agent, comprising vermiculite, a silane coupling agent and an organic phosphate ester which are arranged in sequence. The vermiculite surface contains hydroxyl groups, the silane coupling agent contains amino groups and alkoxy groups, and the organic phosphate ester contains phosphate groups and unesterified hydroxyl groups. On the one hand, the alkoxy groups of the silane coupling agent generate silanol (Si-OH) after a hydrolysis reaction, and the silanol and the hydroxyl groups on the vermiculite surface form a chemical bond through a condensation reaction, thereby connecting the silane coupling agent and the vermiculite to obtain the silane coupling agent-modified vermiculite. On the other hand, the amino groups of the silane coupling agent and the phosphate groups of the organic phosphate ester also form a chemical bond through a condensation reaction, thereby connecting the organic phosphate ester to the silane coupling agent-modified vermiculite, thereby forming a "silicon-phosphorus" modified layer structure composed of the silane coupling agent and the organic phosphate ester on the vermiculite surface, thereby obtaining the modified vermiculite carbonizing agent. Compared with conventional phosphide-modified vermiculite, the technical solution of the present invention utilizes the heat-resistant and non-flammable properties of vermiculite and the good reactivity of the silane coupling agent to effectively increase the loading amount of organic phosphate on the vermiculite surface, and utilizes the "silicon-phosphorus" modification layer in the modified vermiculite carbonizing agent and the multiple flame retardant mechanisms of catalytic carbonization, free radical quenching, physical barrier, etc. played by vermiculite during the combustion process of polyurethane materials to improve the thermal stability and flame retardant efficiency of organic phosphides, thereby significantly improving the actual flame retardant effect of the modified vermiculite carbonizing agent in the polymer matrix, and can solve the problems of low carbonization rate and poor flame retardant performance of existing polyurethanes.

[0031] The technical solution of the present invention also provides a method for preparing a flame-retardant polyurethane material. During the polyurethane synthesis process, unreacted active hydroxyl groups in a modified vermiculite charring agent, polyester polyol, and polyether polyol are used to construct a soft segment, and an isocyanate prepolymer is used to construct a hard segment. The soft and hard segments undergo a condensation reaction to prepare the flame-retardant polyurethane material. When heated, the resulting flame-retardant polyurethane material uses the polymer itself as a carbon source. The polyphosphoric acid produced by the decomposition of the modified vermiculite charring agent can rapidly react with the polymer matrix, catalyzing the degradation of weak bonds (such as urethane bonds) in the polyurethane while rapidly forming char. This method can compensate for the insufficient charring agent content in traditional flame-retardant polyurethane materials and significantly improve the material's charring rate and flame retardancy. During the combustion process, the "silicon-phosphorus" modified layer structure of the modified vermiculite carbonizing agent can also form multiple protective layers on the surface of the substrate: the inner layer is a phosphorus-containing protective carbon layer formed by polyphosphoric acid catalyzing the polyurethane matrix, the middle layer is a silica protective layer formed by silane at high temperature, and the outermost layer is a thermal insulation layer formed after the vermiculite is thermally peeled off and migrated to the surface of the material. This multiple protection mechanism significantly improves the stability and density of the carbon layer, preventing it from oxidative degradation at high temperatures, thereby effectively inhibiting the quality loss of the material. In addition, the "silicon-phosphorus" modified layer structure on the surface of the modified vermiculite carbonizing agent can form a hydrogen bond cross-linking network with the urethane bonds in the polyurethane molecular chain, improving the interfacial compatibility between the inorganic vermiculite and the polymer matrix, and giving full play to the mechanical strengthening effect of the inorganic material on the matrix. The presence of the "silicon-phosphorus" modified layer structure can also promote the peeling and dispersion of the modified vermiculite carbonizing agent in the polyurethane matrix, avoiding uneven dispersion that affects the carbonization and mechanical properties of the composite material. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] During the polyurethane synthesis process, the ratio of polyols, isocyanates, and chain extenders can be adjusted to create polyurethane materials with varying properties to meet the needs of diverse applications such as elastomers, foams, and adhesives. However, like most polymers, polyurethane readily burns in air, generating large amounts of molten droplets, heat, and toxic and corrosive gases, posing a potential fire hazard. Therefore, flame-retardant modification of polyurethane is of great industrial significance.

[0036] The liquid oxygen-containing phosphoric acid released by the thermal decomposition of organophosphorus flame retardants can cover the surface of the substrate and promote the dehydration and esterification of the substrate to form a molten substance. The protective carbon layer formed after the substance solidifies on the surface of the unburned substrate has the functions of heat insulation, oxygen isolation, delaying the spread of flames, and adsorbing toxic smoke. However, most organophosphorus flame retardants are liquid phosphorus, which has defects such as poor thermal stability and high volatility. They easily react with oxygen in high temperature environments and enter the air, causing the phosphorus content in the flame retardant material to decrease. Therefore, the actual flame retardant efficiency of the phosphorus-containing compound in the polymer matrix is ​​affected, and the carbonization effect of the material and the quality of the carbon layer also decrease. It is easily oxidized and cracked under the impact of heat flow and flame, and cannot significantly improve the fire safety of the material. Therefore, in order to further increase the actual phosphorus content in the flame retardant material, and then improve the coverage area and quality of the carbonization of the material, it is the key to improving the flame retardant effect of the composite material.

[0037] To address this issue, researchers typically use microencapsulation technology to improve the thermal stability of organophosphorus flame retardants and their actual flame retardant efficiency in the matrix. However, in the absence of a charring agent, the charring effect of a single-component microencapsulated modified organophosphorus flame retardant on the matrix is ​​still insufficient. In addition, the resin material used as the shell easily releases toxic gases during combustion, posing a threat to human health and the ecological environment. Therefore, developing a green, environmentally friendly, and highly efficient charring phosphorus-containing flame retardant system and using it to improve the flame retardant properties of polyurethane materials is one of the research focuses in the field of flame retardancy.

[0038] In view of this, the present invention proposes a modified vermiculite charring agent, comprising vermiculite, a silane coupling agent and an organic phosphate arranged in sequence, wherein the silane coupling agent comprises an aminosilane coupling agent, the organic phosphate contains a phosphate group and a hydroxyl group, and the silane coupling agent is connected to the vermiculite and the organic phosphate respectively through chemical bonds.

[0039] Currently, phosphate treatment of vermiculite with organophosphates is primarily achieved through physical compounding or intercalation. However, these conventional modification methods cannot effectively guarantee the actual flame retardant efficiency of the prepared phosphated vermiculite in the polymer matrix. In the technical solution of the present invention, the surface of the vermiculite contains hydroxyl groups, the silane coupling agent contains alkoxy groups and amino groups (-NH2), and the organic phosphate contains phosphate groups (-PO3H2) and unesterified hydroxyl groups (-OH): on the one hand, the alkoxy groups of the silane coupling agent generate silanol (Si-OH) in a hydrolysis reaction, and a stable chemical bond can be formed by a condensation reaction between the silanol and the hydroxyl groups on the surface of the vermiculite, thereby connecting the silane coupling agent and the vermiculite to obtain a silane coupling agent-modified vermiculite; on the other hand, the amino groups on the surface of the silane coupling agent react with the phosphate groups contained in the organic phosphate to form phosphoramide, so that the organic phosphate is connected to the silane coupling agent, thereby forming a "silicon-phosphorus" modification layer composed of the silane coupling agent and the organic phosphate on the surface of the vermiculite, thereby obtaining a modified vermiculite carbon-forming agent. Compared with conventional phosphated modified vermiculite, the technical solution of the present invention utilizes the heat-resistant and non-flammable properties of vermiculite, the good reactivity of the silane coupling agent, and the synergistic effect between the two, effectively increasing the loading amount of organic phosphide on the vermiculite surface and its thermal stability, thereby facilitating the improvement of the actual flame retardant effect of the modified vermiculite carbonizing agent in the polymer matrix. These are related to the "silicon-phosphorus" modification layer and the multiple flame retardant mechanisms of vermiculite during the combustion process of polyurethane materials, such as catalytic carbonization, free radical quenching, and physical barrier.

[0040] In an embodiment of the present invention, the organic phosphate includes any one of 2-ethylhexyl phosphate, mono(2-methylpropyl) phosphate, and isooctyl phosphate. The technical solution of the present invention utilizes a phosphate containing two unesterified hydroxyl groups to phosphorylate vermiculite. On the one hand, the phosphate provides a phosphate group that reacts with the amino group of the silane coupling agent through a condensation reaction to form a chemical bond, thereby connecting the organic phosphate to the silane coupling agent-modified vermiculite surface. On the other hand, during the subsequent preparation of the flame-retardant polyurethane material, these unesterified hydroxyl groups act as active hydroxyl groups and can participate in the polyurethane curing process, reacting with the polyol and isophorone diisocyanate prepolymer to synthesize the polyurethane in situ through a condensation reaction. At the same time, the organic phosphate used in the present invention contains highly branched alkane chains: the alkane chains are hydrophobic and can reduce the hydrophilicity of the vermiculite surface when attached to the surface of the vermiculite, which is beneficial to improving the dispersion effect of the modified vermiculite in the polyurethane matrix; on the other hand, the highly branched alkane chain structure can improve the thermal stability of the phosphorus-nitrogen chemical bond (PN), thereby improving the flame retardant efficiency of the modified vermiculite carbonizing agent; in addition, the structure can also undergo cross-linking and rearrangement reactions during the combustion process, which has a positive effect on improving the quality of the carbon layer and the degree of graphitization, thereby inhibiting further thermal degradation of the polyurethane material.

[0041] In an embodiment of the present invention, the silane coupling agent includes any one of N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane. The present invention selects three silane coupling agents, namely, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane, as reaction raw materials. These silane coupling agents have low steric hindrance between the short-chain alkoxy groups (Si-OR) contained in their molecules, exhibit high reactivity, and can be rapidly hydrolyzed to form multiple Si-OH groups, which facilitates the stable adsorption of the silane coupling agent on the vermiculite surface and provides a foundation for the subsequent grafting of organophosphates. Because the amino group at the end of the silane coupling agent can react with the hydroxyl group of the organophosphate through nucleophilic substitution or condensation reactions, forming a highly thermally stable PN chemical bond, it can enhance the bonding strength between the silane coupling agent and the organophosphate and increase the loading of the organophosphate on the vermiculite surface. In addition, the silicon element provided by the silane coupling agent can synergistically exert a flame retardant effect with the organophosphate, improve the thermal stability of the residual carbon, and increase the char formation rate of the composite material.

[0042] The present invention provides a method for preparing the modified vermiculite carbonizing agent, comprising the following steps:

[0043] Mixing a silane coupling agent, ethanol, and deionized water to obtain a silane coupling agent solution, mixing vermiculite with the silane coupling agent solution and adjusting the pH to alkaline, performing a first condensation reaction to obtain a first suspension, performing solid-liquid separation on the first suspension to obtain a first solid, washing and drying the first solid to obtain silane coupling agent-modified vermiculite;

[0044] An organic phosphate ester and anhydrous ethanol are mixed to obtain an organic phosphate ester solution, the silane coupling agent modified vermiculite and the organic phosphate ester solution are mixed and heated to obtain a second suspension, the second suspension is subjected to solid-liquid separation to obtain a second solid, the second solid is washed and dried to obtain a modified vermiculite carbonizing agent.

[0045] In the process of preparing silane coupling agent-modified vermiculite, a silane coupling agent, ethanol and deionized water are first mixed to prepare a silane coupling agent solution, and then the silane coupling agent solution and vermiculite are mixed to carry out a condensation reaction to prepare the silane coupling agent-modified vermiculite. Such an arrangement can avoid the hydration of water molecules with hydroxyl groups on the vermiculite surface due to the preferential dispersion of vermiculite in water, thereby affecting the reaction degree of silanol (Si-OH) generated by the hydrolysis of the silane coupling agent with the hydroxyl groups on the vermiculite surface. In the process of preparing a silane-modified vermiculite carbonizing agent, an organic phosphate ester and anhydrous ethanol are first mixed to obtain an organic phosphate ester solution, and then the organic phosphate ester solution and the prepared silane coupling agent-modified vermiculite are mixed. The amino groups of the silane coupling agent-modified vermiculite react with the phosphate groups on the organic phosphate ester to form a chemical bond, thereby connecting the organic phosphate ester to the silane coupling agent-modified vermiculite to obtain a modified vermiculite carbonizing agent. Compared with directly mixing the organic phosphate, anhydrous ethanol and silane coupling agent modified vermiculite, the method of first mixing the organic phosphate and anhydrous ethanol to obtain an organic phosphate solution and then mixing the organic phosphate solution with the silane coupling agent modified vermiculite is conducive to the full reaction of the organic phosphate solution and the silane coupling agent modified vermiculite.

[0046] In an embodiment of the present invention, the mass ratio of the vermiculite, deionized water, silane coupling agent and anhydrous ethanol is 15:30:(1.5-5):(150-300).

[0047] The technical solution of the present invention sets the mass ratio of vermiculite to silane coupling agent at 30:(3-10), and the mass ratio of deionized water to anhydrous ethanol at 1:(5-10). If the amount of silane coupling agent is too low, its reaction with the hydroxyl groups on the vermiculite surface will be inhibited, resulting in low reactivity of the resulting silane coupling agent-modified vermiculite. If the amount of silane coupling agent is too high, it will easily trigger a crosslinking reaction on the vermiculite surface, causing the resulting silane coupling agent-modified vermiculite flakes to easily agglomerate, affecting the subsequent phosphating modification. When the mass ratio of vermiculite to silane coupling agent is within the above range, the hydroxyl groups (-OH) on the vermiculite surface and the silanols (Si-OH) generated by the hydrolysis of the silane coupling agent can fully undergo condensation reaction, forming sufficient Si-O-Si covalent bonds, effectively reducing the hydrophilicity of the vermiculite and providing favorable conditions for subsequent modification with organic phosphates. When the mass ratio of deionized water to anhydrous ethanol is less than 1:5, the activity of the hydrolysis reaction of the silane coupling agent is too high, and it is easy to self-polymerize and gel, thereby affecting the formation of the Si-O-Si covalent network on the vermiculite surface; when the mass ratio of deionized water to anhydrous ethanol is greater than 1:10, the amount of water used is too small, which is easy to hinder the condensation reaction of the silane coupling agent, reduce the reaction activity of the silane coupling agent with the vermiculite surface, and thus affect the subsequent phosphating modification effect.

[0048] In an embodiment of the present invention, the mass ratio of the silane coupling agent modified vermiculite and the organic phosphate is 1: (1 to 4). When the mass ratio of the silane coupling agent modified vermiculite and the organic phosphate is greater than 1:4, the excessive organic phosphate causes the acidity of the system to be too high, inhibiting the degree of reaction between the amino group and the phosphate group, and easily destroying the stability of the "silicon-phosphorus" modified layer structure; when the mass ratio of the silane coupling agent modified vermiculite and the organic phosphate is less than 1:1, the grafting rate of the organic phosphate on the surface of the silane coupling agent modified vermiculite is reduced, thereby affecting the flame retardant efficiency of the modified vermiculite carbonizing agent. When the amount of the silane coupling agent modified vermiculite and the organic phosphate is set within the above range, it is conducive to the formation of the "silicon-phosphorus" modified layer structure, thereby improving the compatibility between the modified vermiculite carbonizing agent and the polyol and the degree of reaction with the isocyanate prepolymer, and improving the flame retardant properties and mechanical properties of the polymer material.

[0049] In an embodiment of the present invention, after the vermiculite is mixed with a silane coupling agent solution, the pH value is adjusted to 8-10. The technical solution of the present invention uses 1 mol / L NaOH to adjust the pH value of the system. Setting the pH value within the above range is conducive to the hydrolysis of the alkoxy groups of the silane coupling agent to form silanols (Si-OH), and promotes the condensation reaction between the Si-OH structure of the silane coupling agent and the hydroxyl groups on the vermiculite surface, thereby forming a stable chemical bond. This process not only promotes the uniform distribution of the silane coupling agent on the vermiculite surface, but also enhances the reactivity and stability of the vermiculite.

[0050] In an embodiment of the present invention, the temperature of the first condensation reaction is 40° C. to 60° C. For example, the temperature of the first condensation reaction may be 40° C., 45° C., 50° C., 55° C. or 60° C.

[0051] In an embodiment of the present invention, the first condensation reaction time is 1.5 hours to 2.5 hours. For example, the first condensation reaction time can be 1.5 hours, 2 hours or 2.5 hours.

[0052] When the temperature of the first condensation reaction is too low or the reaction time is too short, the hydrolysis rate of the silane coupling agent is slow, resulting in a decrease in its reactivity with the hydroxyl groups on the vermiculite surface, which in turn affects the effect of the subsequent phosphating modification. When the temperature of the first condensation reaction is too high or the reaction time is too long, the silane coupling agent will undergo excessive hydrolysis, resulting in rapid intermolecular condensation of the generated Si-OH groups to form oligomers or gels, which will reduce the degree of binding between the silane coupling agent and the hydroxyl groups on the vermiculite surface and reduce the degree of modification of the vermiculite surface. In addition, high temperatures may also trigger unnecessary side reactions, further reducing the degree of reaction between the silane coupling agent and the vermiculite. When the temperature and time of the first condensation reaction are set within the above range, the silane coupling agent can fully hydrolyze and undergo sufficient condensation reaction with the hydroxyl groups on the vermiculite surface, ensuring the successful preparation of silane coupling agent-modified vermiculite.

[0053] In an embodiment of the present invention, the heating temperature is 90° C. to 120° C. Exemplarily, the heating temperature may be 90° C., 100° C., 110° C. or 120° C.

[0054] In an embodiment of the present invention, the heating time is 6 hours to 12 hours. Exemplarily, the heating time can be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.

[0055] When the heating temperature is less than 90°C, the temperature is too low, and the reactivity of the phosphate groups and amino groups is low, resulting in a low yield of the "silicon-phosphorus" modified layer structure formed on the vermiculite surface. When the heating temperature is greater than 120°C, the temperature is too high, and the "silicon-phosphorus" modified layer structure formed on the vermiculite surface is easily destroyed, thereby affecting the flame retardancy and mechanical properties of the flame-retardant polyurethane material. When the heating time is less than 6 hours, the reaction time is too short, and the degree of reaction between the organic phosphate and the silane coupling agent-modified vermiculite is low, resulting in poor regularity of the "silicon-phosphorus" modified layer structure on the vermiculite surface. When the heating time is greater than 12 hours, the reaction time is too long, and the graft structure formed between the silane coupling agent-modified vermiculite and the organic phosphate is destroyed, which is not conducive to the formation of the "silicon-phosphorus" modified layer structure. If the reaction temperature is too high or too low or the reaction time is too long or too short, it will affect the integrity of the "silicon-phosphorus" modification layer structure in the modified vermiculite carbonizing agent, reduce the compatibility and dispersibility of the modified vermiculite carbonizing agent in the polyurethane matrix, and thus affect the flame retardant properties and mechanical properties of the flame retardant polyurethane material.

[0056] The present invention proposes an application of a modified vermiculite high-efficiency charring agent in the preparation of a flame-retardant polyurethane material. The modified vermiculite high-efficiency charring agent includes the modified vermiculite charring agent described in the aforementioned technical solution, or includes a modified vermiculite charring agent prepared according to the preparation method of the modified vermiculite charring agent described in the aforementioned technical solution.

[0057] Vermiculite is an inorganic layered silicate containing active hydroxyl groups on its surface and between its layers, exhibiting excellent heat resistance. The addition of layered silicates improves the thermal stability of flame retardants and their actual flame retardant efficiency within a polymer matrix, effectively reducing the flame retardant loading and achieving efficient charring. The present invention chemically modifies vermiculite using a silane coupling agent and an organophosphate ester, producing a highly efficient modified vermiculite charring agent. This agent is then used to prepare flame-retardant polyurethane materials, improving their flame retardancy.

[0058] The present invention provides a method for preparing a flame retardant polyurethane material, comprising the following steps:

[0059] Dehydrating the polyester polyol and the polyether polyol to obtain dehydrated polyester polyol and dehydrated polyol;

[0060] Mixing a modified vermiculite carbonizing agent, dehydrated polyester polyol, dehydrated polyether polyol and a metal catalyst to obtain a reaction base material;

[0061] Adding isophorone diisocyanate prepolymer to the reaction base to carry out a second condensation reaction to obtain a flame retardant polyurethane material; wherein:

[0062] The modified vermiculite carbonizing agent is the modified vermiculite carbonizing agent described in the aforementioned technical solution, or is a modified vermiculite carbonizing agent prepared by the preparation method of the modified vermiculite carbonizing agent described in the aforementioned technical solution.

[0063] In the technical solution of the present invention, since the vermiculite surface and the organic phosphate in the modified vermiculite charring agent contain unreacted active hydroxyl groups, the unreacted active hydroxyl groups on the surface of the modified vermiculite charring agent are used together with polyester polyol and polyether polyol to construct the soft segment of the polyurethane. The hydroxyl groups (-OH) in the modified vermiculite charring agent, polyester polyol and polyether polyol undergo a condensation reaction with the isocyanate groups (-NCO) in the isophorone diisocyanate prepolymer to form urethane bonds (-NHCOO-). After the reaction is completed, a flame-retardant polyurethane material is obtained.

[0064] The resulting flame-retardant polyurethane material uses the polymer itself as a carbon source and incorporates the flame-retardant elements phosphorus and silicon into the polymer matrix. Carbamate bonds are among the weakest bonds in the polyurethane molecular chain and are susceptible to hydrolysis or thermal decomposition by acidic catalysts. When heated, the phosphates produced by the decomposition of organic phosphates come into contact with the weak carbamate bonds in the polyurethane and catalyze their degradation and cleavage. The phosphates further dehydrate to form polyphosphates such as pyrophosphate and metaphosphate, which promote the cross-linking and recombination of the thermal decomposition products on the surface of the remaining substrate, forming a protective carbon layer, thereby compensating for the impact of insufficient carbonizing agents on the material's combustion range. During the combustion process, the "silicon-phosphorus" modified layer structure of the modified vermiculite carbonizing agent can form multiple protective layers on the surface of the substrate: the inner layer is a phosphorus-containing protective carbon layer formed by polyphosphoric acid catalyzing the polyurethane matrix; the middle layer is a silica protective layer formed by silane at high temperature, which combines with the residual carbon to form a ceramic-like protective layer, significantly improving the quality of the carbon layer; the outermost layer is an insulating layer formed when the vermiculite is thermally peeled and migrates to the surface of the substrate. Such multiple protection mechanisms significantly improve the stability and density of the carbon layer, prevent it from oxidative degradation at high temperatures, and thus effectively inhibit the quality loss of the material at high temperatures.

[0065] Compared with unmodified vermiculite, the "silicon-phosphorus" modified layer structure contained in the modified vermiculite high-efficiency carbonizing agent can form a multiple hydrogen bond network with the urethane bonds of the polyurethane matrix, thereby improving the compatibility of inorganic vermiculite with the polymer matrix; in addition, the presence of the "silicon-phosphorus" modified layer structure can also weaken the van der Waals force between vermiculite flakes, promote the exfoliation and dispersion of inorganic vermiculite in the polyurethane matrix, and avoid the impact of uneven dispersion on the carbonization and mechanical properties of the composite material.

[0066] In an embodiment of the present invention, the polyester polyol and polyether polyol are dehydrated by vacuum dehydration at a temperature of 90°C to 110°C for a period of 2 to 4 hours. For example, the dehydration temperature can be 90°C, 100°C, 105°C, or 110°C, and the dehydration time can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. Water can deplete the isocyanate content in the prepolymer, thereby affecting the reaction between the isocyanate and the modified vermiculite charring agent, the polyester polyol, and the polyether polyol, leading to a decrease in the flame retardant and mechanical properties of the flame-retardant polyurethane material. In one embodiment of the present invention, the polyester polyol and polyether polyol are dehydrated at 105°C under vacuum for 2.5 hours to reduce the water content of both the polyester polyol and the polyether polyol to less than 0.03wt%. This prevents the reaction of water with the isocyanate prepolymer to produce carbon dioxide and other byproducts, ensuring the high quality and excellent performance of the flame-retardant polyurethane material.

[0067] In an embodiment of the present invention, the step of mixing the modified vermiculite carbonizing agent, dehydrated polyester polyol, dehydrated polyether polyol and a metal catalyst to obtain a mixture specifically comprises:

[0068] The modified vermiculite carbonizing agent is dispersed in tetrahydrofuran to obtain a modified vermiculite carbonizing agent dispersion, and the modified vermiculite carbonizing agent dispersion, dehydrated polyester polyol, dehydrated polyether polyol and a metal catalyst are mixed to obtain a reaction base material.

[0069] In an embodiment of the present invention, the number-average molecular weight of the polyester polyol is 1,000 to 4,000. The molecular weight of the polyester polyol affects the molecular chain length and crosslink density of the flame-retardant polyurethane material produced. Polyester polyols with higher molecular weights generally form longer molecular chains, which helps enhance the tensile strength of the material. However, excessively high molecular weights lead to excessively high viscosity of the soft segment components, hindering the uniform dispersion of the modified vermiculite charring agent in the matrix and reducing the multi-synergistic flame retardant effect of the "silicon-phosphorus" modification layer during the matrix combustion process. Polyester polyols with lower molecular weights form shorter molecular chains, which helps enhance the crosslink density of the matrix. However, excessively low molecular weights lead to excessively high crosslink density, which reduces the flame retardant activity of the "silicon-phosphorus" modification layer structure, affecting the coverage of the multiple protective layers formed during combustion, and thus reducing the flame retardancy of the polyurethane material. In one embodiment of the present invention, a polyester polyol with a molecular weight of 3,000 is used to improve the dispersion of the modified vermiculite charring agent in the matrix, fully utilizing the advantages of the "silicon-phosphorus" modification layer structure on the vermiculite surface, thereby improving the flame retardancy and mechanical properties of the polyurethane material.

[0070] In an embodiment of the present invention, the polyether polyol includes polyethylene glycol 400. An appropriate amount of polyethylene glycol 400 can improve the mechanical properties of the material. In addition, during the combustion process, polyethylene glycol 400 can also participate in the formation of a protective char layer, which is beneficial to improving the flame retardant properties of the polyurethane material.

[0071] In an embodiment of the present invention, the mass ratio of the modified vermiculite carbonizing agent, the dehydrated polyester polyol, the dehydrated polyether polyol and the metal catalyst is 1:(6-13):(0.6-1.3):(0.04-0.08).

[0072] In an embodiment of the present invention, the mass ratio of the modified vermiculite carbonizing agent to the isophorone diisocyanate prepolymer is 1:(8-13).

[0073] By adjusting the ratio between modified vermiculite carbonizing agent, polyester polyol, polyether polyol and isocyanate prepolymer, a flame-retardant polyurethane material with good comprehensive performance is obtained. When the amount of the modified vermiculite carbonizing agent is too much, it may cause acid hydrolysis of polyester polyol or isophorone diisocyanate prepolymer, destroying the integrity of the ester bond of polyester polyol and the urethane bond of isophorone diisocyanate prepolymer, thereby affecting the synthesis process and final performance of the flame-retardant polyurethane material; when the amount of the modified vermiculite carbonizing agent is too little, it leads to incomplete "silicon-phosphorus" modified layer structure in the soft segment component, and the phosphorus and silicon content in the flame-retardant polyurethane material is low, thereby affecting the flame retardant properties and mechanical properties of the material. When the amount of the modified vermiculite carbonizing agent, polyester polyol, polyether polyol and isophorone diisocyanate prepolymer is set within the above range, each component can fully exert its synergistic effect, thereby forming a uniform hydrogen bond cross-linked network in the matrix and forming a uniform and continuous dense carbon layer during the combustion process. This not only improves the charring effect and mechanical strength of flame-retardant polyurethane materials, but also gives them the possibility of industrialization.

[0074] In an embodiment of the present invention, the metal catalyst includes dibutyltin dilaurate.

[0075] In an embodiment of the present invention, the temperature of the second condensation reaction is 60° C. to 80° C. For example, the temperature of the second condensation reaction may be 60° C., 65° C., 70° C., 75° C. or 80° C.

[0076] In an embodiment of the present invention, the second condensation reaction time is 3.5 hours to 6.5 hours. For example, the second condensation reaction time can be 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours or 6.5 hours.

[0077] If the second condensation reaction temperature is too high or too low, or the second condensation reaction time is too long or too short, it will affect the reaction activity between the modified vermiculite carbonizing agent, polyester polyol, polyether polyol and isophorone diisocyanate prepolymer, thereby inhibiting the dispersion of the modified vermiculite carbonizing agent in the matrix, and failing to fully exert the multiple flame retardant effects of vermiculite and the "silicon-phosphorus" modified layer structure and the interaction between the modified vermiculite carbonizing agent and the molecular chain, resulting in the flame retardant properties and mechanical properties of the flame retardant polyurethane material being affected.

[0078] The present invention provides a flame retardant polyurethane material, which is prepared according to the preparation method of the flame retardant polyurethane material.

[0079] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0080] In the following examples, all examples and comparative examples use the same vermiculite, which is raw vermiculite powder from Xinjiang purchased from Xinnuo Mineral Products Processing Plant in Lingshou County, with a particle size of 325 mesh and an interlayer distance of 1.47 nm.

[0081] Example 1

[0082] A method for preparing a flame retardant polyurethane material comprises the following steps:

[0083] 1. Preparation of modified vermiculite carbonizing agent:

[0084] (1) adding 3.75 g of diethylenetriaminopropyltrimethoxysilane to an alcohol-water system prepared by mixing 30 g of deionized water and 210 g of anhydrous ethanol to obtain a silane coupling agent solution;

[0085] (2) 15 g of vermiculite was mixed with a silane coupling agent solution, and the pH value was then adjusted to 9 with a 1 mol / L NaOH solution. The mixture was refluxed at a constant temperature of 45° C. for 2 h for a first condensation reaction. After the reaction was completed, the mixture was cooled and discharged, and filtered, washed, and dried in sequence to obtain silane coupling agent-modified vermiculite.

[0086] (3) 37.5 g of 2-ethylhexyl phosphate was dispersed in 150 g of anhydrous ethanol to obtain an organic phosphate solution, and then 15 g of silane coupling agent-modified vermiculite was added to the organic phosphate solution. The mixture was refluxed at a constant temperature of 100° C. for 10 h, cooled and discharged, and filtered, washed, and dried in sequence to obtain a solid. The solid was ground and sieved through a 300-mesh sieve to obtain a modified vermiculite carbonizing agent.

[0087] 2. Preparation of flame retardant polyurethane materials:

[0088] (1) 12.88 g of modified vermiculite carbonizing agent was dispersed in 51.52 g of tetrahydrofuran to obtain a modified vermiculite carbonizing agent dispersion; polyester polyol (molecular weight 3000) and polyethylene glycol 400 were dehydrated under vacuum at 105° C. for 2.5 h to obtain dehydrated polyester polyol and dehydrated polyethylene glycol 400;

[0089] (2) The modified vermiculite carbonizing agent dispersion, 103.04 g of dehydrated polyester polyol, 10.30 g of dehydrated polyethylene glycol 400 and 0.77 g of dibutyltin dilaurate were added to a three-necked flask at the same time, and mixed evenly at a temperature of 80°C to obtain a reaction base material. Subsequently, 131.38 g of isophorone diisocyanate prepolymer was added to the reaction base material, and the mixture was stirred at a constant temperature of 80°C for 5 hours to carry out a second condensation reaction to obtain a flame-retardant polyurethane material.

[0090] Example 2

[0091] Compared with Example 1, the difference is that in the step of preparing the modified vermiculite carbon-forming agent:

[0092] The mass of diethylenetriaminopropyltrimethoxysilane is 2 g, and the mass of anhydrous ethanol is 150 g;

[0093] Adjust the pH to 8.

[0094] Example 3

[0095] Compared with Example 1, the difference is that in the step of preparing the modified vermiculite carbon-forming agent:

[0096] The mass of diethylenetriaminopropyltrimethoxysilane is 5 g, and the mass of anhydrous ethanol is 275 g;

[0097] Adjust the pH to 9.5.

[0098] Example 4

[0099] Compared with Example 1, the difference is that in the step of preparing the modified vermiculite carbon-forming agent:

[0100] 22.5 g of 2-ethylhexyl phosphate was dispersed in 90 g of anhydrous ethanol.

[0101] Example 5

[0102] Compared with Example 1, the difference is that in the step of preparing the modified vermiculite carbon-forming agent:

[0103] 45 g of 2-ethylhexyl phosphate was dispersed in 180 g of anhydrous ethanol.

[0104] Example 6

[0105] Compared with Example 1, the difference lies in that in the step of preparing the flame retardant polyurethane material:

[0106] 90.16 g of dehydrated polyester polyol, 9.02 g of dehydrated polyethylene glycol 400, 0.68 g of dibutyltin dilaurate and 115.92 g of isophorone diisocyanate prepolymer were added to a three-necked flask in sequence.

[0107] Example 7

[0108] Compared with Example 1, the difference lies in that in the step of preparing the flame retardant polyurethane material:

[0109] 115.92 g of dehydrated polyester polyol, 11.59 g of dehydrated polyethylene glycol 400, 0.97 g of dibutyltin dilaurate and 148.12 g of isophorone diisocyanate prepolymer were added to a three-necked flask in sequence.

[0110] Example 8

[0111] Compared with Example 1, the difference is that the amounts of diethylenetriaminopropyltrimethoxysilane and anhydrous ethanol are 0.5 g and 120 g respectively;

[0112] The amounts of 2-ethylhexyl phosphate and anhydrous ethanol are 7.5 g and 30 g respectively;

[0113] The amounts of the dehydrated polyester polyol, dehydrated polyethylene glycol 400, dibutyltin dilaurate and isophorone diisocyanate prepolymer used are 161 g, 16.1 g, 1.11 g and 180.32 g, respectively.

[0114] Example 9

[0115] Compared with Example 1, the difference is that the amounts of diethylenetriaminopropyltrimethoxysilane and anhydrous ethanol are 6 g and 330 g respectively;

[0116] The amounts of 2-ethylhexyl phosphate and anhydrous ethanol are 67.5 g and 270 g respectively;

[0117] The amounts of the dehydrated polyester polyol, the dehydrated polyethylene glycol 400, the dibutyltin dilaurate and the isophorone diisocyanate prepolymer used are 64.4 g, 6.44 g, 0.52 g and 90.16 g, respectively.

[0118] Comparative Example 1

[0119] Compared with Example 1, the difference is that step (2) is not performed in the step of preparing the modified vermiculite carbonizing agent, that is, the step of modifying the silane coupling agent is not performed, and organic phosphate modified vermiculite is used instead of the modified vermiculite carbonizing agent to prepare the flame retardant polyurethane material.

[0120] Comparative Example 2

[0121] Compared with Example 1, the difference is that step (3) is not performed in the step of preparing the modified vermiculite carbonizing agent, that is, the step of organic phosphate modification is not performed, and silane coupling agent-modified vermiculite is used instead of the modified vermiculite carbonizing agent to prepare the flame retardant polyurethane material.

[0122] Comparative Example 3

[0123] Compared with Example 1, the difference is that unmodified vermiculite is used instead of the modified vermiculite carbonizing agent to prepare the flame retardant polyurethane material.

[0124] Comparative Example 4

[0125] Compared with Example 1, the difference is that an equal amount of triphenyl phosphate is used instead of 2-ethylhexyl phosphate.

[0126] Performance Testing

[0127] The flame retardant properties of the flame retardant polyurethane materials obtained in Examples 1-9 and Comparative Examples 1-4 were tested and analyzed, and the analysis method was as follows:

[0128] Residual carbon rate / expansion ratio test: The flame-retardant polyurethane material was placed in a muffle furnace and heated to 700°C for carbonization. The volume ratio and residual carbon content before and after expansion were observed. The test results are shown in Table 1.

[0129] Limiting Oxygen Index (LOI) test: The test was conducted in accordance with GB / T 2406.2-2009. The test results are shown in Table 1.

[0130] Vertical burning (UL-94) test: The test was conducted in accordance with GB / T 2408-2021 standard. The test results are shown in Table 1.

[0131] Tensile strength test: The test was carried out in accordance with GB / T 1040.1-2018. The test results are shown in Table 1.

[0132] Table 1 Performance test results of Examples 1-9 and Comparative Examples 1-4

[0133]

[0134]

[0135] According to the test results in Table 1, the following conclusions can be drawn:

[0136] (1) Compared with comparative examples 1-4, when the modified vermiculite charring agent of Examples 1-7 is applied to the flame retardant of polyurethane, the tensile strength of the corresponding materials is generally higher, and the materials have relatively excellent charring and flame retardant properties, indicating that the modified vermiculite high-efficiency charring agent and flame retardant polyurethane material proposed in the present invention can effectively enhance the flame retardant effect of the modified vermiculite high-efficiency charring agent in the flame retardant polyurethane material.

[0137] (2) According to the test results of Example 1 and Comparative Examples 1-2, when a silane coupling agent or an organic phosphate is absent, the flame retardant effect and mechanical strengthening effect of the modified vermiculite carbonizing agent in the polyurethane matrix cannot be significantly improved.

[0138] (3) By comparing the test results of Example 1 with those of Comparative Example 3, it can be seen that the flame retardant polyurethane material prepared by using the modified vermiculite carbonizing agent of the present invention has better carbonization, flame retardant properties and mechanical strength than the flame retardant polyurethane material prepared by using unmodified vermiculite.

[0139] (4) Compared with Comparative Example 4, the flame retardant polyurethane material prepared in Example 1 has more excellent flame retardant properties and tensile strength. It can be seen from the results that the use of the modified vermiculite high-efficiency charring agent and flame retardant polyurethane material proposed in the present invention can effectively enhance the flame retardant effect and mechanical reinforcement effect of the modified vermiculite high-efficiency charring agent in the flame retardant polyurethane material.

[0140] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention specification under the technical concept of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A modified vermiculite carbonizing agent, characterized in that: The invention comprises vermiculite, a silane coupling agent and an organic phosphate ester which are arranged in sequence, wherein the silane coupling agent comprises an aminosilane coupling agent, the organic phosphate ester contains a phosphate group and an unesterified hydroxyl group, and the silane coupling agent is connected to the vermiculite and the organic phosphate ester respectively through chemical bonds.

2. The modified vermiculite charcoal-forming agent according to claim 1, wherein The silane coupling agent includes any one of N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane; and / or, The organic phosphate includes any one of 2-ethylhexyl phosphate, mono(2-methylpropyl) phosphate, and isooctyl phosphate.

3. A method for preparing the modified vermiculite carbonizing agent according to claim 1 or 2, characterized in that: The following steps are involved: Mixing a silane coupling agent, ethanol, and deionized water to obtain a silane coupling agent solution, mixing vermiculite with the silane coupling agent solution and adjusting the pH to alkaline, performing a first condensation reaction to obtain a first suspension, performing solid-liquid separation on the first suspension to obtain a first solid, washing and drying the first solid to obtain silane coupling agent-modified vermiculite; An organic phosphate ester and anhydrous ethanol are mixed to obtain an organic phosphate ester solution, the silane coupling agent modified vermiculite and the organic phosphate ester solution are mixed and heated to obtain a second suspension, the second suspension is subjected to solid-liquid separation to obtain a second solid, the second solid is washed and dried to obtain a modified vermiculite carbonizing agent.

4. The method for preparing the modified vermiculite carbonizing agent according to claim 3, wherein: The mass ratio of the vermiculite, deionized water, silane coupling agent and anhydrous ethanol is 15:30:(1.5-5):(150-300).

5. The method for preparing the modified vermiculite carbonizing agent according to claim 3, wherein: The mass ratio of the silane coupling agent modified vermiculite to the organic phosphate is 1:(1-4).

6. The method for preparing the modified vermiculite carbonizing agent according to claim 3, wherein: The heating temperature is 90°C to 120°C; and / or, The heating time is 6 hours to 12 hours.

7. Application of a modified vermiculite high-efficiency carbonizing agent in the preparation of flame-retardant polyurethane materials, characterized in that: The modified vermiculite charcoal-forming agent includes the modified vermiculite charcoal-forming agent according to claim 1 or 2, or includes the modified vermiculite charcoal-forming agent prepared by the preparation method of the modified vermiculite charcoal-forming agent according to any one of claims 3 to 6.

8. A method for preparing a flame retardant polyurethane material, characterized in that: The following steps are involved: Dehydrating the polyester polyol and the polyether polyol to obtain dehydrated polyester polyol and dehydrated polyether polyol; Mixing a modified vermiculite carbonizing agent, dehydrated polyester polyol, dehydrated polyether polyol and a metal catalyst to obtain a reaction base material; adding isophorone diisocyanate prepolymer to the reaction base to carry out a second condensation reaction to obtain a flame retardant polyurethane material; The modified vermiculite carbonizing agent is the modified vermiculite carbonizing agent according to claim 1 or 2, or is prepared by the preparation method of the modified vermiculite carbonizing agent according to any one of claims 3 to 6.

9. The method for preparing a flame retardant polyurethane material according to claim 8, wherein: The number average molecular weight of the polyester polyol is 1000 to 4000; and / or, The polyether polyol includes polyethylene glycol 400; and / or, The mass ratio of the modified vermiculite carbonizing agent, dehydrated polyester polyol, dehydrated polyether polyol and metal catalyst is 1: (6-13): (0.6-1.3): (0.04-0.08); and / or, The mass ratio of the modified vermiculite carbonizing agent to the isophorone diisocyanate prepolymer is 1:(8-13); and / or, The temperature of the second condensation reaction is 60°C to 90°C; and / or, The second condensation reaction time is 3.5h to 6.5h.

10. A flame retardant polyurethane material, characterized in that: The flame retardant polyurethane material is prepared according to the method for preparing the flame retardant polyurethane material according to claim 8 or 9.

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