Efficient flame-retardant smoke-suppression polyurethane and preparation method thereof

Abstract

The invention discloses efficient flame-retardant smoke-suppressing polyurethane and a preparation method thereof.The efficient flame-retardant smoke-suppressing polyurethane comprises a material A and a material B. The material A is prepared from liquid polyether macromolecular dihydric alcohol, liquid polyether macromolecular trihydric alcohol, polyether carbonate polyol, a chain extender, a catalyst, a hydroxylation flame-retardant smoke-suppressing agent and a surface functional ceramic forming auxiliary; the material B is prepared from castor oil and diisocyanate; wherein the hydroxylated flame-retardant smoke suppressant is formed by carrying out ion exchange reaction on ammonium polyphosphate, an ammonium molybdate smoke suppressant and an alcohol amine modifier, and the surface functional ceramic forming additive is obtained by carrying out self-polymerization on a polyphenol compound on the surface of the inorganic ceramic forming additive to form a polymer coating. According to the efficient flame-retardant smoke-suppression polyurethane provided by the invention, organic solvents such as DMF are not used in the preparation process, organic solvent pollution is eliminated from the source, the limit oxygen index of the prepared polyurethane is greater than 28%, and the prepared polyurethane passes a V-0 grade through a UL-94 vertical combustion test, is low in maximum smoke density and has excellent comprehensive properties such as mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant materials technology, specifically relating to a high-efficiency flame retardant and smoke-suppressing polyurethane and its preparation method. Background Technology

[0002] my country is the world's largest manufacturer and consumer of synthetic leather. Its products are widely used in footwear, apparel, home furnishings, sofas, automobiles, high-speed rail, shipbuilding, sporting goods, and other manufacturing sectors, playing a vital role in ensuring the supply of essential goods and supporting high-end manufacturing. In recent years, with the improvement of people's living standards and changes in consumption concepts, the market demand for high-performance, high-quality, and environmentally friendly synthetic leather has shown a continuous upward trend.

[0003] Although my country's synthetic leather industry is booming, it still faces challenges such as severe organic solvent pollution and the urgent need for breakthroughs in high-performance eco-friendly synthetic leather technology. On the one hand, current synthetic leather manufacturing primarily relies on solvent-based polyurethane, including solvent-based surface treatment agents, solvent-based topcoat resins, foaming layer resins, and solvent-based adhesives. The production process releases large amounts of toxic solvents such as dimethylformamide, toluene, and methyl ethyl ketone, seriously harming workers' health and causing severe environmental pollution and resource waste. On the other hand, many industries, including aviation, high-speed rail, automotive interior leather, furniture leather, home decoration leather, and fire-fighting clothing leather, require eco-friendly synthetic leather to be flame-retardant. For example, the national standard GB 38262-2019, "Combustion Characteristics of Passenger Vehicle Interior Materials," clearly stipulates that the vertical burning rate of leather products for passenger vehicle seats should be ≤100mm / min, and the limiting oxygen index (LOI) should be ≥27%. However, the LOI value of finished synthetic leather products is generally below 21%, classifying them as flammable materials. Furthermore, the combustion process generates large amounts of toxic fumes and gases, seriously threatening people's lives and property. Therefore, the development of high-efficiency flame-retardant and smoke-suppressing polyurethane synthetic leather is of great practical significance.

[0004] The main raw materials for producing polyurethane synthetic leather are polyurethane resin and base fabric. Adding flame retardants to the polyurethane resin is the most common method for manufacturing flame-retardant synthetic leather. Chinese patent CN119390929A discloses "A solvent-free polyurethane resin for automotive leather and its preparation method and application." This resin includes component A and component B. Component A is prepared from long-chain alkyl-modified organosilicon polyether diol, polyether diol, polyether triol, chain extender, catalyst, and flame retardant. The flame retardant is an environmentally friendly halogen-free flame retardant of aluminum hypophosphite type. Chinese patent CN113774679A discloses "A solvent-free polyurethane synthetic leather with low smoke toxicity and high oxygen index and its preparation method and application," wherein the flame-retardant polyurethane adhesive layer contains 2-5 parts of mesoporous hydroxystannate smoke suppressant and 40-60 parts of microencapsulated halogen-free flame retardant.

[0005] However, current methods for manufacturing flame-retardant synthetic leather primarily involve directly dispersing additive flame retardants such as aluminum hydroxide, ammonium polyphosphate, and phosphate esters into polyurethane slurry to enhance the leather's flame retardancy. This approach generally suffers from drawbacks such as high additive dosage, low flame retardant efficiency, poor dispersion and compatibility with the polyurethane matrix, easy migration and precipitation, and negative impacts on key physical properties of the synthetic leather, including mechanical properties. Therefore, optimizing the compatibility between flame retardants and polyurethane resins is one of the key issues that urgently needs to be addressed in manufacturing high-performance, eco-friendly flame-retardant synthetic leather. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the prior art by providing a highly efficient flame-retardant and smoke-suppressing polyurethane and its preparation method. The flame-retardant and smoke-suppressing agent provided by this invention forms covalent and hydrogen bonds with the polyurethane matrix, overcoming the drawbacks of traditional additive flame retardants such as large dosage, poor dispersibility and compatibility, and easy migration and precipitation. Only a relatively low dosage is required to impart highly efficient flame-retardant and smoke-suppressing properties to the polyurethane.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The preparation method of the above-mentioned high-efficiency flame-retardant and smoke-suppressing polyurethane provided by the present invention includes the following steps: (1) Preparation of hydroxylated flame retardant and smoke suppressant: Ammonium polyphosphate and ammonium molybdate smoke suppressant were added to an ethanol aqueous solution, an alcohol amine modifier was added, the mixture was heated and stirred to react, cooled, filtered and dried to obtain hydroxylated flame retardant and smoke suppressant; (2) Preparation of surface functionalized ceramic-forming aid: Inorganic ceramic-forming aid is dispersed in water, polyphenolic compound is added, ultrasonic dispersion is performed, pH adjuster is added, the reaction is stirred at room temperature, and the mixture is dried after vacuum distillation to obtain surface functionalized ceramic-forming aid. (3) Preparation of material A: By weight, 40-60 parts of liquid polyether macromolecular diol, 10-15 parts of liquid polyether macromolecular triol, 20-40 parts of polyether carbonate polyol, 6-10 parts of chain extender and 0.1-0.5 parts of catalyst are placed in a reaction vessel, 20-40 parts of hydroxylated flame retardant and smoke suppressant and 2-8 parts of surface functionalized ceramic additive are added, and the mixture is heated and stirred to obtain material A; (4) Preparation of material B: Place 20-40 parts of castor oil and 30-50 parts of diisocyanate in a reaction vessel, heat and stir to react, and obtain material B; (5) Preparation of flame-retardant and smoke-suppressing polyurethane: Mix A and B materials evenly, coat and dry to cure, and the high-efficiency flame-retardant and smoke-suppressing polyurethane is obtained.

[0008] In the above scheme, ammonium polyphosphate is a commonly used inorganic flame retardant with high phosphorus and nitrogen content, non-toxic and odorless, inexpensive, and halogen-free. It can not only serve as an ideal acid source in chemically intumescent flame retardant systems but also partially act as a gas source. Ammonium molybdate smoke suppressants are common, high-performance inorganic smoke suppressants and flame retardants. Structurally, both ammonium polyphosphate and ammonium molybdate smoke suppressants contain a large amount of -NH4+. + This facilitates ion exchange reactions with the primary / secondary amine groups in alkanolamine modifiers, thereby modifying the surface of ammonium polyphosphate and ammonium molybdate smoke suppressants to prepare hydroxylated flame retardant smoke suppressants. During the polyurethane curing process, the abundant polyhydroxyl groups on the surface of the hydroxylated flame retardant smoke suppressant not only undergo stepwise addition polymerization with isocyanate groups to form urethane bonds, but also provide hydrogen bonding sites.

[0009] In the above scheme, the inorganic ceramic-forming additives can be rapidly sintered into a ceramic body with certain mechanical strength under fire or high temperature conditions, thereby increasing the strength of the carbon layer and playing a role in heat insulation and oxygen isolation. Taking advantage of the high reactivity of the phenolic hydroxyl groups of polyphenolic compounds, which can self-polymerize to form a polymer coating on the material surface under alkaline conditions in the presence of oxygen, the inorganic ceramic-forming additives can be surface functionalized to improve their dispersibility and compatibility with the polyurethane matrix.

[0010] In the above scheme, polyether carbonate polyol, also known as carbon dioxide polyether, is a copolymer of propylene oxide and carbon dioxide with hydroxyl-terminated ends, containing carbonate and ether bonds in the molecular chain. It not only has the properties of polycarbonate, but also has the advantages of low-temperature flexibility of polyether polyol. The polyurethane materials prepared from it have excellent properties such as oxidation resistance, wear resistance, chemical resistance, and hydrolysis resistance.

[0011] Preferably, in step (1), the ammonium molybdate smoke suppressant is any one of ammonium heptamolybdate, ammonium octamolybdate, ammonium dodecamolybdate, and ammonium phosphomolybdate; The amine modifier is any one of diethanolamine, 2-amino-1,3-propanediol, 3-amino-1,2-propanediol, and 3-methylamino-1,2-propanediol. The mass ratio of ammonium polyphosphate, ammonium molybdate smoke suppressant and alcohol amine modifier is 10:(1-3):(4-8).

[0012] Preferably, in step (1), the volume fraction of ethanol in the aqueous ethanol solution is 75%-95%; the reaction temperature is 70-90℃; and the reaction time is 2-6h.

[0013] Preferably, in step (2), the inorganic ceramic-forming aid is any one of zinc borate, zinc oxide, aluminum oxide, zirconium oxide, and boron carbide; The polyphenolic compounds are any one of tannic acid, epicatechin gallate, and dopamine; The pH adjuster is any one of ammonia, sodium carbonate, sodium bicarbonate, or tris(hydroxymethyl)aminomethane. The mass ratio of inorganic ceramic-forming aids to polyphenolic compounds is 10:(3-5).

[0014] Preferably, in step (2), the pH of the system solution is adjusted to 8-10; the reaction time is 4-8h.

[0015] Preferably, in step (3), the liquid polyether macromolecular diol is either polyethylene glycol or polypropylene glycol with a relative molecular mass of 1000-3000; The liquid polyether macromolecular triol is a polyoxypropylene triol with a relative molecular weight of 3000-6000; The polyether carbonate polyol is a polycarbonate diol with a relative molecular mass of 2000 or a polycarbonate triol with a relative molecular mass of 3000. The chain extender is any one of 1,3-propanediol, 1,4-butanediol, diethylene glycol, and triethylene glycol. The catalyst is any one of bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, bismuth naphthenate, and dimethylaminoethyl ether.

[0016] Preferably, in step (3), the stirring temperature is 50-80℃ and the stirring time is 0.5-2h.

[0017] Preferably, in step (4), the diisocyanate is any one of 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; the reaction temperature is 65-85℃, and the reaction time is 1-3h.

[0018] Preferably, in step (5), the mass ratio of material A to material B is 100:(60-80); and the material is cured at 120-150℃.

[0019] Compared with the prior art, the present invention has the following innovative features: (1) The hydroxylated flame retardant and smoke suppressant provided by the present invention modifies the surface of ammonium polyphosphate and ammonium molybdate smoke suppressant with an alcohol amine modifier, which can form covalent bonds and hydrogen bonds with the polyurethane matrix, thereby enhancing the interfacial bonding force between the two and solving the common problems of poor compatibility, easy migration and precipitation, and deterioration of mechanical properties of traditional external flame retardants with polyurethane.

[0020] (2) The polyphenolic compound surface functionalized ceramic additive provided by the present invention has good compatibility with polyurethane matrix. It can quickly generate a solid ceramic body during combustion, exert a synergistic flame retardant effect with the char layer, make up for the problem of low flame retardant efficiency of single flame retardant element or traditional multi-component compound system, and effectively reduce the amount of flame retardant used.

[0021] (3) The high-efficiency flame-retardant and smoke-suppressing polyurethane provided by the present invention uses eco-friendly raw materials such as polyether carbonate polyol and castor oil. The preparation process does not use organic solvents such as DMF, thus eliminating organic solvent pollution from the source and significantly reducing energy consumption and production costs. At the same time, the prepared polyurethane has excellent comprehensive properties such as mechanical properties, high flame retardant efficiency, and releases less smoke when burning, and has good market prospects. Attached Figure Description

[0022] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of this application and other related content, and should not be considered as limitations on this application.

[0023] In the accompanying drawings of the instruction manual: Figure 1 This is a scanning electron microscope comparison image of hydroxylated flame retardant and smoke suppressant (a) and ammonium polyphosphate (b) in a specific embodiment of the present invention.

[0024] Figure 2 The curves showing the changes in heat release rate (HRR) (a), total heat release (THR) (b), and total smoke production (TSP) over time are compared between the high-efficiency flame-retardant and smoke-suppressing polyurethane prepared in Specific Embodiment 1 of the present invention and the polyurethane prepared in Comparative Example 1. Detailed Implementation

[0025] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0026] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0027] Those skilled in the art will recognize that the chemical reactions described in this invention can be suitably used to prepare many other compounds of this invention, and that other methods for preparing the compounds of this invention are considered to be within the scope of this invention. For example, the synthesis of those non-illustrative compounds according to this invention can be successfully accomplished by those skilled in the art through modification methods, such as by appropriately protecting interfering groups, by utilizing other known reagents besides those described in this invention, or by making some conventional modifications to the reaction conditions. Furthermore, the reactions disclosed in this invention or the known reaction conditions are also generally accepted to be applicable to the preparation of other compounds of this invention.

[0028] The raw materials used in the following embodiments of this invention are described below: ammonium polyphosphate, ammonium molybdate smoke suppressant, alkanolamine modifier, inorganic ceramic-forming aid, polyphenolic compound, pH adjuster, liquid polyether macromolecular diol, liquid polyether macromolecular triol, polyether carbonate polyol, chain extender, and catalyst, etc., are all commercially available conventional products; among them, the polycarbonate diol with a relative molecular mass of 2000 is graded C-2090, and the polycarbonate triol with a relative molecular mass of 3000 is graded Poly-CO2 3010-53.

[0029] The performance testing methods used in the following embodiments of the present invention are described as follows: mechanical property testing is conducted according to GB / T 1040.2-2006 standard; limiting oxygen index testing is conducted according to GB / T 2406.1-2008 standard; UL-94 vertical burning test is conducted according to GB / T 2408-2021 standard; smoke density testing is conducted according to GB / T 8323.2-2008 standard; and cone calorimetry testing is conducted according to ISO5660-1:2015 standard. Example 1

[0030] This embodiment provides a method for preparing high-efficiency flame-retardant and smoke-suppressing polyurethane. The raw materials are in parts by weight, and the specific preparation steps are as follows: (1) Preparation of hydroxylated flame retardant and smoke suppressant: 10 parts of ammonium polyphosphate and 2 parts of ammonium octamolate were added to 100 parts of ethanol aqueous solution with a volume concentration of 90%, and 6 parts of 3-amino-1,2-propanediol were added. The mixture was heated to 90℃ and stirred for 2 hours. After cooling and filtration, it was dried to obtain hydroxylated flame retardant and smoke suppressant. (2) Preparation of surface functionalized ceramic additive: 10 parts of zinc borate were dispersed in 100 parts of water, 5 parts of tannic acid were added, the mixture was ultrasonically dispersed, and tris(hydroxymethyl)aminomethane was added to adjust the pH to 9. The mixture was stirred at room temperature for 4 hours, and then dried after vacuum distillation to obtain the surface functionalized ceramic additive. (3) Preparation of material A: By weight, 60 parts of polypropylene glycol with a relative molecular mass of 2000, 15 parts of polyoxypropylene triol with a relative molecular mass of 6000, 40 parts of polycarbonate triol with a relative molecular mass of 3000, 6 parts of 1,4-butanediol and 0.5 parts of bismuth isooctanoate were placed in a reaction vessel, and 30 parts of hydroxylated flame retardant and smoke suppressant and 5 parts of surface functionalized ceramic-forming agent were added. The mixture was heated and stirred at 60°C for 1 hour to obtain material A. (4) Preparation of material B: 40 parts castor oil and 40 parts isophorone diisocyanate were placed in a reaction vessel, heated to 85°C and stirred for 2 hours to obtain material B; (5) Preparation of flame-retardant and smoke-suppressing polyurethane: Mix 100 parts of material A and 60 parts of material B evenly, coat and dry at 140℃ to obtain high-efficiency flame-retardant and smoke-suppressing polyurethane. Example 2

[0031] This embodiment provides a method for preparing high-efficiency flame-retardant and smoke-suppressing polyurethane. The raw materials are in parts by weight, and the specific preparation steps are as follows: (1) Preparation of hydroxylated flame retardant and smoke suppressant: 10 parts of ammonium polyphosphate and 1 part of ammonium phosphomolybdate were added to 100 parts of ethanol aqueous solution with a volume concentration of 75%, and 4 parts of diethanolamine were added. The mixture was heated to 70°C and stirred for 6 hours. After cooling, filtration and drying, the hydroxylated flame retardant and smoke suppressant was obtained. (2) Preparation of surface functionalized ceramic additive: 10 parts of zirconium oxide were dispersed in 100 parts of water, 4 parts of epicatechin gallate were added, ultrasonically dispersed, sodium bicarbonate was added to adjust the pH to 8, the reaction was stirred at room temperature for 8 hours, and dried after vacuum distillation to obtain the surface functionalized ceramic additive. (3) Preparation of material A: By weight, 40 parts of polyethylene glycol with a relative molecular mass of 1000, 10 parts of polypropylene triol with a relative molecular mass of 3000, 20 parts of polycarbonate diol with a relative molecular mass of 2000, 6 parts of diethylene glycol and 0.3 parts of bismuth neodecanoate were placed in a reaction vessel, and 20 parts of hydroxylated flame retardant and smoke suppressant and 2 parts of surface functionalized ceramic additive were added. The mixture was heated and stirred at 50°C for 2 hours to obtain material A. (4) Preparation of material B: 20 ​​parts castor oil and 50 parts dicyclohexylmethane diisocyanate were placed in a reaction vessel, heated to 80°C and stirred for 3 hours to obtain material B; (5) Preparation of flame-retardant and smoke-suppressing polyurethane: Mix 100 parts of material A and 70 parts of material B evenly, coat and dry at 150°C to obtain high-efficiency flame-retardant and smoke-suppressing polyurethane. Example 3

[0032] This embodiment provides a method for preparing high-efficiency flame-retardant and smoke-suppressing polyurethane. The raw materials are in parts by weight, and the specific preparation steps are as follows: (1) Preparation of hydroxylated flame retardant and smoke suppressant: 10 parts of ammonium polyphosphate and 3 parts of ammonium heptamolybdate were added to 100 parts of ethanol aqueous solution with a volume concentration of 80%, and 8 parts of 3-methylamino-1,2-propanediol were added. The mixture was heated to 80°C and stirred for 4 hours. After cooling, filtration and drying, the hydroxylated flame retardant and smoke suppressant was obtained. (2) Preparation of surface functionalized ceramic additive: 10 parts boron carbide were dispersed in 100 parts water, 3 parts dopamine were added, ultrasonic dispersion was performed, sodium bicarbonate was added to adjust the pH to 10, the reaction was stirred at room temperature for 6 hours, and the mixture was dried after vacuum distillation to obtain the surface functionalized ceramic additive. (3) Preparation of material A: By weight, 60 parts of polypropylene glycol with a relative molecular mass of 3000, 12 parts of polyoxypropylene triol with a relative molecular mass of 4000, 30 parts of polycarbonate diol with a relative molecular mass of 2000, 10 parts of triethylene glycol and 0.1 parts of bismuth laurate were placed in a reaction vessel, and 35 parts of hydroxylated flame retardant and smoke suppressant and 8 parts of surface functionalized ceramic additive were added. The mixture was heated and stirred at 80°C for 0.5 h to obtain material A. (4) Preparation of material B: 30 parts of castor oil and 30 parts of 4,4'-diphenylmethane diisocyanate were placed in a reaction vessel, heated to 65°C and stirred for 1 hour to obtain material B; (5) Preparation of flame-retardant and smoke-suppressing polyurethane: Mix 100 parts of material A and 80 parts of material B evenly, coat and dry at 130℃ to obtain high-efficiency flame-retardant and smoke-suppressing polyurethane. Example 4

[0033] This embodiment provides a method for preparing high-efficiency flame-retardant and smoke-suppressing polyurethane. The raw materials are in parts by weight, and the specific preparation steps are as follows: (1) Preparation of hydroxylated flame retardant and smoke suppressant: 10 parts of ammonium polyphosphate and 3 parts of ammonium dodecylmolybdate were added to 100 parts of ethanol aqueous solution with a volume concentration of 80%, and 6 parts of 2-amino-1,3-propanediol were added. The mixture was heated to 80°C and stirred for 3 hours. After cooling, filtration and drying, the hydroxylated flame retardant and smoke suppressant was obtained. (2) Preparation of surface functionalized ceramic additive: 10 parts of alumina were dispersed in 100 parts of water, 3 parts of epicatechin gallate were added, ultrasonically dispersed, ammonia was added to adjust the pH to 8, the reaction was stirred at room temperature for 5 hours, and the mixture was dried after vacuum distillation to obtain the surface functionalized ceramic additive. (3) Preparation of material A: By weight, 50 parts of polyethylene glycol with a relative molecular mass of 2000, 15 parts of polypropylene triol with a relative molecular mass of 3000, 30 parts of polycarbonate triol with a relative molecular mass of 3000, 8 parts of 1,3-propanediol and 0.5 parts of bismuth isooctanoate were placed in a reaction vessel, and 40 parts of hydroxylated flame retardant and smoke suppressant and 6 parts of surface functionalized ceramic-forming agent were added. The mixture was heated and stirred at 70°C for 2 hours to obtain material A. (4) Preparation of material B: 30 parts castor oil and 30 parts hexamethylene diisocyanate were placed in a reaction vessel, heated to 75°C and stirred for 3 hours to obtain material B; (5) Preparation of flame-retardant and smoke-suppressing polyurethane: Mix 100 parts of material A and 70 parts of material B evenly, coat and dry at 140℃ to obtain high-efficiency flame-retardant and smoke-suppressing polyurethane.

[0034] Comparative Example 1 This comparative example provides a method for preparing pure polyurethane. Compared with Example 1, the only difference is that steps (1) and (2) are omitted, and hydroxylated flame retardant and smoke suppressant and surface functionalization ceramic additives are not added in step (3). Other raw materials and preparation processes are the same.

[0035] Comparative Example 2 This comparative example provides a method for preparing flame-retardant and smoke-suppressing polyurethane. Compared with Example 1, the only difference is that steps (1) and (2) are omitted. In step (3), the hydroxylated flame retardant and smoke suppressant and the surface functionalized ceramic additive are replaced with 10 parts of unmodified ammonium polyphosphate, 2 parts of ammonium octamolate and 10 parts of zinc borate. Other raw materials and preparation processes are the same.

[0036] Comparative Example 3 This comparative example provides a method for preparing flame-retardant polyurethane. Compared with Example 1, the only difference is that step (2) is omitted. In step (3), only hydroxylated flame retardant and smoke suppressant is added, and no surface functionalization ceramic additive is added. Other raw materials and preparation processes are the same.

[0037] Comparative Example 4 This comparative example provides a method for preparing smoke-suppressing polyurethane. Compared with Example 1, the only difference is that step (1) is omitted. In step (3), only surface functionalization ceramic additives are added, and hydroxylated flame retardant and smoke suppressant are not added. Other raw materials and preparation processes are the same.

[0038] The scanning electron microscope (SEM) comparison images of the hydroxylated flame retardant and smoke suppressant prepared in Example 1 and the unmodified ammonium polyphosphate are shown below. Figure 1 As shown, the surface of unmodified ammonium polyphosphate is relatively smooth. After modification with an alkanolamine modifier, there is obvious adhesion and aggregation between the ammonium polyphosphate particles. At the same time, it can be observed that ammonium molybdate smoke suppressant is adsorbed on its surface. This is due to the enhanced hydrogen bonding and van der Waals forces between the flame retardant and smoke suppressant particles after the ion exchange reaction. This indicates that the alkanolamine modifier was successfully modified onto the surface of ammonium polyphosphate and ammonium molybdate smoke suppressant, and hydroxylated flame retardant smoke suppressant was successfully prepared.

[0039] The performance test results of the flame-retardant and smoke-suppressing polyurethanes prepared in Examples 1-4 and Comparative Examples 1-4 were statistically summarized and the results are shown in Table 1.

[0040] Table 1 Performance test results of flame-retardant and smoke-suppressing polyurethanes prepared in Examples 1-4 and Comparative Examples 1-4

[0041] As shown in Table 1, the high-efficiency flame-retardant and smoke-suppressing polyurethanes prepared using Examples 1-4 of this invention have a limiting oxygen index greater than 28%, pass the V-0 rating in the UL-94 vertical burning test, and have a maximum smoke density of less than 25%. Furthermore, they maintain good elongation at break while improving tensile strength. In contrast, when the same amount of unmodified flame retardant was directly added to Comparative Example 2, the limiting oxygen index was only 24.6%, it could only pass the V-1 rating, and the maximum smoke density was 38.4%, while also deteriorating the mechanical properties of the polyurethane. Moreover, when only hydroxylated flame-retardant and smoke-suppressing agents or surface-functionalized ceramic-forming additives were added to Comparative Examples 3 and 4, the flame-retardant and smoke-suppressing performance of the polyurethanes was significantly lower than that of Examples 1-4. This indicates that both additives exert a synergistic flame-retardant mechanism, improving the flame-retardant and smoke-suppressing efficiency. In addition, Figure 2 The cone calorimetry test results of the polyurethanes prepared in Example 1 and Comparative Example 1 were compared, further verifying that the hydroxylated flame retardant and smoke suppressant agent and the surface functionalized ceramic-forming agent effectively reduce the heat release rate, total heat release, and total smoke generation of the polyurethane. Therefore, the preparation method of the high-efficiency flame retardant and smoke suppressant polyurethane provided by this invention is a new technology worthy of widespread application.

[0042] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection for this invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of this invention, or any equivalent structural or procedural transformations made using the content of this specification, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of patent protection for this invention.

Claims

1. A method for preparing a high-efficiency flame-retardant and smoke-suppressing polyurethane, characterized in that, Includes the following steps: (1) Preparation of hydroxylated flame retardant and smoke suppressant: Ammonium polyphosphate and ammonium molybdate smoke suppressant were added to an ethanol aqueous solution, an alcohol amine modifier was added, the mixture was heated and stirred to react, cooled, filtered and dried to obtain hydroxylated flame retardant and smoke suppressant; (2) Preparation of surface functionalized ceramic-forming aid: Inorganic ceramic-forming aid is dispersed in water, polyphenolic compound is added, ultrasonic dispersion is performed, pH adjuster is added, the reaction is stirred at room temperature, and the mixture is dried after vacuum distillation to obtain surface functionalized ceramic-forming aid. (3) Preparation of material A: By weight, 40-60 parts of liquid polyether macromolecular diol, 10-15 parts of liquid polyether macromolecular triol, 20-40 parts of polyether carbonate polyol, 6-10 parts of chain extender and 0.1-0.5 parts of catalyst are placed in a reaction vessel, 20-40 parts of hydroxylated flame retardant and smoke suppressant and 2-8 parts of surface functionalized ceramic additive are added, and the mixture is heated and stirred to obtain material A; (4) Preparation of material B: Place 20-40 parts of castor oil and 30-50 parts of diisocyanate in a reaction vessel, heat and stir to react, and obtain material B; (5) Preparation of flame-retardant and smoke-suppressing polyurethane: Mix A and B materials evenly, coat and dry to cure, and the high-efficiency flame-retardant and smoke-suppressing polyurethane is obtained.

2. The preparation method according to claim 1, characterized in that, In step (1), the ammonium molybdate smoke suppressant is any one of ammonium heptamolybdate, ammonium octamolybdate, ammonium dodecamolybdate, or ammonium phosphomolybdate; The amine modifier is any one of diethanolamine, 2-amino-1,3-propanediol, 3-amino-1,2-propanediol, and 3-methylamino-1,2-propanediol. The mass ratio of ammonium polyphosphate, ammonium molybdate smoke suppressant and alcohol amine modifier is 10:(1-3):(4-8).

3. The preparation method according to claim 1, characterized in that, In step (1), the volume fraction of ethanol in the aqueous ethanol solution is 75%-95%; the reaction temperature is 70-90℃; and the reaction time is 2-6h.

4. The preparation method according to claim 1, characterized in that, In step (2), the inorganic ceramic-forming aid is any one of zinc borate, zinc oxide, aluminum oxide, zirconium oxide, and boron carbide; The polyphenolic compounds are any one of tannic acid, epicatechin gallate, and dopamine; The pH adjuster is any one of ammonia, sodium carbonate, sodium bicarbonate, or tris(hydroxymethyl)aminomethane. The mass ratio of inorganic ceramic-forming aids to polyphenolic compounds is 10:(3-5).

5. The preparation method according to claim 1, characterized in that, In step (2), the pH of the system solution is adjusted to 8-10; the reaction time is 4-8 h.

6. The preparation method according to claim 1, characterized in that, In step (3), the liquid polyether macromolecular diol is either polyethylene glycol or polypropylene glycol with a relative molecular mass of 1000-3000; The liquid polyether macromolecular triol is a polyoxypropylene triol with a relative molecular weight of 3000-6000; The polyether carbonate polyol is a polycarbonate diol with a relative molecular mass of 2000 or a polycarbonate triol with a relative molecular mass of 3000. The chain extender is any one of 1,3-propanediol, 1,4-butanediol, diethylene glycol, and triethylene glycol. The catalyst is any one of bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, bismuth naphthenate, and dimethylaminoethyl ether.

7. The preparation method according to claim 1, characterized in that, In step (3), the stirring temperature is 50-80℃ and the stirring time is 0.5-2h.

8. The preparation method according to claim 1, characterized in that, In step (4), the diisocyanate is any one of 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; the reaction temperature is 65-85℃ and the reaction time is 1-3h.

9. The preparation method according to claim 1, characterized in that, In step (5), the mass ratio of material A to material B is 100:(60-80); and the material is cured at 120-150℃.

10. The high-efficiency flame-retardant and smoke-suppressing polyurethane prepared by the preparation method according to any one of claims 1-9.

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