Flame-retardant waterborne polyurethane dispersions, methods of making, and uses thereof

Abstract

The application discloses a kind of flame-retardant waterborne polyurethane dispersions, preparation method and its application, the flame-retardant waterborne polyurethane dispersion is by introducing flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) or its derivative and the reactive polysiloxane to polyurethane main chain, form P-O and Si-O synergistic flame-retardant effect, so that the flame-retardant property of fabric is improved, the heat release rate of material, flame spread rate and decomposition rate are significantly reduced and do not reduce the water resistance of product.The flame-retardant waterborne polyurethane dispersion of the application can be widely applied in fabric material, and has wide application prospect and large market value.

Description

Technical Field

[0001] This invention relates to the field of waterborne polyurethane materials, specifically to a novel flame-retardant waterborne polyurethane dispersion, its preparation, and its application in fabrics. Background Technology

[0002] With the increasing national requirements for environmental protection and people's growing need for an environmentally friendly environment, waterborne polyurethane, due to its advantages such as being non-toxic, environmentally friendly, and safe, is gradually replacing traditional solvent-based polyurethane and is being used more and more widely in fields such as leather finishing, fabric finishing, and adhesives.

[0003] As is well known, materials such as leather and fabrics are highly flammable and generally require flame-retardant treatment. Polyurethane, with an oxygen index of only 14%–16%, is also classified as flammable. When heated during combustion, depolymerization and cracking produce many complex low-molecular-weight compounds and gaseous toxic substances (HCN, CO, etc.). These substances can continue to burn, releasing a large amount of heat that accelerates the decomposition of polyurethane, creating a positive feedback loop. Therefore, flame retardancy is a crucial issue for the widespread application of polyurethane. Currently, non-reactive flame retardants, such as halogenated and organophosphorus flame retardants, are the most widely used to improve the flame-retardant properties of polyurethane. However, the addition of these flame retardants can affect the performance of polyurethane and even cause environmental pollution, harming human health.

[0004] CN200480043181 discloses a flame-retardant polyurethane and its additives. This patent invented a reactive flame retardant containing halogens such as chlorine and bromine. However, the flame retardants used are all toxic halogens, posing serious health hazards to the environment and human body.

[0005] CN200810204199 discloses a method for preparing high-performance flame-retardant polyester interior textiles. This patent proposes a method of coating the fabric surface with a phosphorus- and nitrogen-containing flame retardant compounded with water-based polyurethane. The resulting textile achieves the national B1 flammability rating, and its smoke toxicity test meets Boeing's BSS7239 standard. However, it has drawbacks such as poor water resistance and easy migration of the flame retardant.

[0006] CN201810928073 discloses a waterborne polyurethane flame-retardant coating for architectural furniture coatings and its preparation method. This patent uses microporous network gluten powder and melamine-based silica aerogel as char-forming flame retardants, which are then uniformly mixed with waterborne polyurethane and other additives to prepare a highly efficient flame-retardant waterborne coating. However, this method affects the compatibility with waterborne polyurethane, causing some fluctuations in the product's performance.

[0007] CN201410815368 discloses an organophosphorus-modified waterborne polyurethane flame-retardant coating and its preparation method. This method introduces phosphorus into the waterborne polyurethane structural chain through a reaction, preparing a halogen-free, environmentally friendly waterborne polyurethane coating. However, this method suffers from poor water resistance and only moderate flame-retardant performance.

[0008] CN201410089774 discloses a method for preparing a polysiloxane-modified polyurethane aqueous dispersion. This invention improves the product's water resistance, chemical resistance, and abrasion resistance; however, the material prepared by this invention has limited improvement in flame retardant properties and cannot be widely used, thus restricting the product's development.

[0009] WO2020 / 130831 A1 discloses a halogen-free flame-retardant waterborne polyurethane dispersion. This method improves the flame retardancy of the product by introducing phosphorus polyols into the polyurethane chain segments. However, the product has a limited lifespan in the textile products used in the application, extremely poor water resistance, and poor overall performance.

[0010] Therefore, how to improve the flame retardant properties of waterborne polyurethane in fabrics while preventing the migration of flame retardants, improving its compatibility and water resistance presents new challenges and development prospects. Summary of the Invention

[0011] To address the problems existing in the prior art, this invention provides a novel and highly efficient flame-retardant waterborne polyurethane dispersion, while reducing the decrease in water resistance of the waterborne polyurethane dispersion on fabrics caused by the introduction of flame retardants.

[0012] Another object of the present invention is to provide a method for preparing this novel flame-retardant waterborne polyurethane dispersion.

[0013] Another object of the present invention is to provide the application of this novel flame-retardant waterborne polyurethane dispersion on fabrics.

[0014] To achieve the above objectives, the present invention adopts the following solution:

[0015] A novel flame-retardant waterborne polyurethane dispersion, comprising the following components by mass percentage based on the total mass of all components:

[0016] A. At least two types of diisocyanates, 20-45 wt%, preferably 22-40 wt%;

[0017] B. At least two polymeric polyols, 35-70 wt%, preferably 40-65 wt%;

[0018] C. At least one hydrophilic compound, 3-15 wt%, preferably 5-10 wt%;

[0019] D. At least one DOPO flame retardant or its derivative, 5-25 wt%, preferably 8-20 wt%;

[0020] E. 0-3.0 wt% of polysiloxane with reactive functional groups, preferably 0-2.0 wt%.

[0021] In one specific embodiment, at least one of the at least two diisocyanates in component A is an aliphatic diisocyanate; preferably, the aliphatic diisocyanate is preferably an alicyclic diisocyanate; more preferably, the alicyclic diisocyanate is selected from any one of isoflurone diisocyanate, 1,4'-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 4,4'-dicyclohexylpropane diisocyanate; even more preferably, the at least two diisocyanates A are 4,4'-dicyclohexylmethane diisocyanate and 1,6-hexyl diisocyanate, with a molar ratio of 1:1.

[0022] In one specific embodiment, component B comprises at least two polymeric polyols, namely at least one polyester polyol and at least one polyether polyol, preferably a polyester polyol with a number average molecular weight of 200-3000 and a polyether polyol with a number average molecular weight of 500-4000; preferably, the molar ratio of the at least one polyester polyol and the at least one polyether polyol is 1:3.3; more preferably, the polyester polyol is a polyester diol, selected from polybutylene adipate diol, poly(ethylene glycol adipate) diol, etc. The polyether polyol is selected from at least one of the following: poly(ethylene glycol adipate), poly(neopentyl adipate), poly(hexyl adipate), poly(hexyl phthalate), poly(ethylene glycol adipate), polycarbonate, or polycaprolactone.

[0023] In one specific embodiment, the hydrophilic compound in component C is a dimethylolalkyl acid, preferably dimethylolpropionic acid or dimethylolbutyric acid.

[0024] In one specific implementation, the DOPO flame retardant in component D has the formula ( The general structural formula of component E is given, wherein the mass percentage of the polysiloxane with reactive functional groups cannot be 0, for example, 0.1~3.0 wt%, preferably 0.2~2.0 wt%.

[0025] ( )

[0026] Wherein, R is selected from hydrogen, a straight or branched hydrocarbon chain, an optionally substituted carbocyclic ring, or an optionally substituted heterocyclic ring; X1 and X2 are sites that can react with isocyanates, each independently selected from hydrogen, hydroxyl, amino, carbamate, or urea; preferably, the carbocyclic ring is selected from cycloalkyl, cycloalkenyl, aryl, or fused carbocyclic groups; the heterocyclic ring includes one or more heteroatoms selected from O, S, N, or Si.

[0027] More preferably, the DOPO flame retardant derivative in component D has the formula ( The general structural formula is given, wherein the mass ratio of the polysiloxane with reactive functional groups in component E is 0-3.0 wt%, preferably 0-2.0 wt%.

[0028] ( )

[0029] Wherein, W is selected from straight-chain or branched hydrocarbon chains or straight-chain or branched hydrocarbon chains containing N or O heteroatoms; Y1, Y2 and Y3 are sites that can react with isocyanates, each independently selected from hydrogen, hydroxyl, amino, carbamate, urea, straight-chain or branched hydrocarbon chains, and Y1, Y2 and Y3 are not simultaneously straight-chain or branched hydrocarbon chains.

[0030] In a specific implementation, the formula ( The DOPO flame retardant derivatives with the general structural formula are prepared by the following steps:

[0031] (1) Add a certain amount of DOPO, graftable siloxane and solvent to a three-necked flask;

[0032] (2) Raise the temperature to 80~120℃ and reflux the reaction for 4~10 h;

[0033] (3) The solution obtained after the reaction is subjected to vacuum distillation at 80~120℃ for 2~4 h to finally prepare the solution of formula ( DOPO flame retardant derivatives with a general structural formula.

[0034] The graftable siloxane is selected from any one of chlorinated siloxanes, siloxanes containing epoxy groups, and siloxanes containing hydroxyl groups; the molar ratio of the PH group of DOPO to the active group in the graftable siloxane is 1.05~1.1:1.

[0035] The solvent is selected from any one of benzene, toluene, tetrahydrofuran, acetone, and N,N-dimethylformamide; the solvent mass percentage is 10-20% based on the total weight of DOPO and the graftable siloxane.

[0036] In one specific embodiment, the polysiloxane with reactive functional groups in component E has the general structural formula of formula (III):

[0037] (III)

[0038] R1 and R2 are each independently selected from hydroxyl, amino, or hydrogen; preferably, the average molecular weight of the polysiloxane is 200-1000.

[0039] In one specific embodiment, the molar ratio of the NCO group in component A to the reactive groups contained in components B to E is (1.1~2):1, preferably (1.2~1.6):1.

[0040] In a preferred embodiment, the novel flame-retardant waterborne polyurethane dispersion further includes an auxiliary component F, which is selected from two or more antioxidants, light stabilizers or ultraviolet absorbers. The amount of the auxiliary component added is 0.2-2.0 wt% of the total weight of components A to E, preferably 0.4-1.0 wt%.

[0041] On the other hand, a method for preparing the aforementioned novel flame-retardant waterborne polyurethane dispersion includes the following steps:

[0042] 1) Mix and react components A, B, C, D, and E in a certain proportion;

[0043] 2) Add catalyst and acetone during the reaction in step 1); then react at 70~90℃ until the theoretical NCO is reached, add acetone to dilute, and prepare the isocyanate-terminated prepolymer;

[0044] 3) Add acetone dilution of component F to the prepolymer of step 2) and stir to mix evenly to obtain G;

[0045] 4) Neutralize the prepolymer G with a neutralizing agent, wherein the molar ratio of the neutralizing agent to component C is (0.6~1):1; preferably, the neutralizing agent is selected from alkali metal hydroxides or tertiary amines; preferably any one of NaOH, KOH, triethylamine, and dimethylethanolamine;

[0046] 5) Add water to the product obtained in step 4) and perform self-emulsification dispersion to obtain a crude emulsion of the waterborne polyurethane dispersion;

[0047] 6) Remove acetone from the crude emulsion dispersed in step 5) and adjust it to the theoretical solid content to obtain a novel flame-retardant waterborne polyurethane dispersion.

[0048] On the other hand, the application of the aforementioned novel flame-retardant waterborne polyurethane dispersion or the novel flame-retardant waterborne polyurethane dispersion prepared by the aforementioned method in fabric coatings is preferably in the application of fabric coatings in the fields of fire suits, military uniforms, military tents, casual sportswear, sofas, seat cushions, postal parcels, protective equipment or medical supplies.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] (1) A novel flame-retardant waterborne polyurethane dispersion of the present invention introduces DOPO or its derivatives and polysiloxane structure into the polyurethane main chain structure. The two can work together to retard flame, and the flame-retardant functional groups are dispersed at the molecular level. It has excellent flame-retardant effect, is environmentally friendly and non-toxic, and produces low smoke. It has a broad market and development prospects.

[0051] (2) The present invention introduces a polysiloxane with certain hydrophobicity, which can reduce the problem of reduced water resistance of fabric coating caused by the introduction of a large number of hydrophilic groups.

[0052] (3) The novel flame-retardant waterborne polyurethane dispersion emulsion of the present invention has high flame retardant performance, excellent water resistance, simple preparation method, easy operation, safety and environmental protection, and wide availability of raw materials. It can be widely used in leather finishing, fabric finishing, adhesives and other fields. Attached Figure Description

[0053] Figure 1 The infrared spectrum of the DOPO derivative prepared in an embodiment of the present invention.

[0054] Figure 2 The DOPO derivative of Example 1 of the present invention 1 H-NMR spectrum.

[0055] Figure 3 As described in Example 2 of the present invention, the DOPO derivative... 1 H-NMR spectrum.

[0056] Figure 4 The DOPO derivative of Example 3 of the present invention 1 H-NMR spectrum. Detailed Implementation

[0057] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0058] A novel flame-retardant waterborne polyurethane dispersion is prepared by reacting the following raw materials:

[0059] A. At least two types of diisocyanates, added in amounts of 20-45 wt%;

[0060] B. At least two polymeric polyols, added in amounts of 35-70 wt%;

[0061] C. At least one hydrophilic compound, added in an amount of 3-15 wt%;

[0062] D. At least one DOPO or its derivative, added in an amount of 5-25 wt%;

[0063] E. A polysiloxane containing reactive groups, added in an amount of 0-3.0 wt%;

[0064] F. At least two adjuvants, including two or more of antioxidants, light stabilizers or ultraviolet absorbers, added in an amount of 0.2-2.0 wt%.

[0065] In a preferred embodiment, the novel flame-retardant waterborne polyurethane dispersion is prepared by reacting raw materials comprising:

[0066] A. At least two types of diisocyanates, added in amounts of 22-40 wt%;

[0067] B. At least two polymeric polyols, added in amounts of 40-65 wt%;

[0068] C. At least one hydrophilic compound, added in an amount of 5-10 wt%;

[0069] D. At least one DOPO or its derivative, added in an amount of 8-20 wt%;

[0070] E. A polysiloxane containing reactive groups, added in an amount of 0-2.0 wt%;

[0071] F. At least two adjuvants, including two or more of antioxidants, light stabilizers and ultraviolet absorbers, added in an amount of 0.4-1.0 wt%.

[0072] The weights of the above components are the mass percentages of the solids in the waterborne polyurethane dispersion, i.e., based on the total mass of components A to F.

[0073] In the aforementioned novel flame-retardant waterborne polyurethane dispersion, the molar ratio of the NCO groups of component A (diisocyanate) to the reactive groups of component B (polymeric diol), component C (hydrophilic compound), component D (flame retardant DOPO or its derivatives), and component E (polysiloxane) is (1.1~2):1, for example, including but not limited to 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, preferably (1.2~1.6):1. The reactive groups may be, for example, hydroxyl, amino, amine, urethane, or urea groups, but are not limited to these.

[0074] In this invention, at least one of the isocyanates in component A is an alicyclic isocyanate, such as any one of isoflurone diisocyanate, 1,4'-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 4,4'-dicyclohexylpropane diisocyanate. The other isocyanate may be tetramethylene diisocyanate, methylpentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethyl diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'- and 2,4'-diphenylmethane diisocyanate, tetramethyl diphenyl diisocyanate, or terephthalic diisocyanate; there are no particular limitations. The molar ratio of the two diisocyanates is not particularly limited and can be adjusted according to the performance requirements of the product, preferably 1:1. In a preferred embodiment, component A comprises two diisocyanates: 4,4'-dicyclohexylmethane diisocyanate and 1,6-hexyl diisocyanate, in a molar ratio of 1:1. This invention utilizes the synergistic combination of two isocyanates during the reaction process, making it easier to control the chain segment distribution and molecular weight, resulting in a dispersion with superior overall performance.

[0075] Component B is a mixture of polyester polyol and polyether polyol. The molar ratio of the two polyols is not particularly limited and can be adjusted according to the performance requirements of the product. A preferred molar ratio is 1:3.3. Preferably, it consists of at least two types of polyols with a number average molecular weight of 200-3000 and polyether polyols with a number average molecular weight of 500-4000. The polyester polyol is polybutylene adipate diol, polyethylene adipate diol, or poly(butylene adipate). The polyols used in this invention are neopentyl diacid glycol diol, poly(neopentyl hexyl adipate) glycol diol, poly(hexyl phthalate) glycol diol, poly(diethylene phthalate) glycol diol, polycarbonate glycol diol, and polycaprolactone glycol diol, preferably polybutylene adipate glycol diol; the polyether polyols are polytetrahydrofuran glycol diol, polypropylene glycol diol, polyethylene glycol diol, polyethylene glycol monomethyl ether, trimethylolpropane ethylene glycol monomethyl ether, and trihydroxypolyoxypropylene ether, preferably polypropylene glycol. The polyester polyol and polyether polyol used in this invention are two different types of polyols, and the combination of these two polyols compensates for the performance deficiencies of a single polyol. The two polyols can meet the application possibilities under more environmental conditions, thus broadening the application range.

[0076] The hydrophilic compound in component C is a dihydroxymethylalkyl acid, preferably dihydroxymethylpropionic acid or dihydroxymethylbutyric acid.

[0077] The flame retardant DOPO described in component D has the following general formula ( ):

[0078] ( )

[0079] In the formula, R is selected from hydrogen, a straight-chain or branched hydrocarbon chain, or an optionally substituted carbide ring, wherein the straight-chain or branched hydrocarbon chain is, for example, a... or The carbocyclic ring is selected from cycloalkyl, cycloalkenyl, aryl, and fused carbocyclic groups; R can also be an optionally substituted heterocycle, wherein the heterocycle is selected from one or more heteroatoms of O, S, or N, preferably, R is an O or N heteroatom. X1 and X2 are sites that can react with isocyanates, selected from hydrogen, hydroxyl, amino, urethane, and urea groups, and X1 and X2 can be the same or different, preferably, X1 and X2 are hydroxyl groups. DOPO and its derivatives possess the advantages of organophosphorus flame retardants, and due to the high chemical and thermal stability of its biphenyl structure, the PC bond in the molecular structure has excellent chemical stability, making its flame retardancy superior to that of general organophosphate flame retardants. Introducing DOPO or its derivatives into polyurethane segments greatly reduces its flame retardancy when used on fabrics, and has a wider market prospect.

[0080] When component D, the flame retardant DOPO, has the general formula ( When the structure of component E is used, the mass percentage of the polysiloxane with reactive functional groups cannot be 0, for example, greater than 0 and less than 3.0 wt%, for example, 0.01~3.0 wt%, preferably 0.2~2.0 wt%.

[0081] Among them, the DOPO derivative of component D can also be a novel DOPO flame retardant containing a new Si-O structure, having the following general structural formula ( ):

[0082] ( )

[0083] In the formula, W is selected from straight-chain or branched hydrocarbon chains or straight-chain or branched hydrocarbon chains containing N or O heteroatoms; wherein, a straight-chain or branched hydrocarbon chain is, for example, a... or Hydrocarbon chains containing N and O heteroatoms, either straight-chain or branched, are, for example, Preferably, W is Y1, Y2, and Y3 are sites that can react with isocyanates, selected from hydrogen, hydroxyl, amino, carbamate, and urea groups, and can also be straight-chain or branched hydrocarbon chains; Y1, Y2, and Y3 can be the same or different. Preferably, Y1, Y2, and Y3 are hydroxyl groups. This invention simultaneously introduces PO and Si-O into the waterborne polyurethane chain segments, forming a molecular-level dispersion of flame-retardant functional groups, while simultaneously generating a synergistic flame-retardant effect of PO and Si-O, thereby improving the flame-retardant properties of the fabric. The heat release rate, flame spread rate, and decomposition rate of the material are significantly reduced without compromising the product's water resistance.

[0084] When component D, the flame retardant DOPO, has the general formula ( When the structure is such that component E has a reactive functional group, the mass percentage of the polysiloxane can be 0, for example, 0~3.0 wt%, preferably 0~2.0 wt%.

[0085] Specifically, the preparation method of the above-mentioned DOPO derivative containing the novel Si-O structure includes the following steps:

[0086] (1) Add a certain amount of DOPO, graftable siloxane and solvent to a three-necked flask, wherein the molar ratio of the pH of DOPO to the active group in the graftable siloxane is 1.05~1.1:1, and the amount of solvent added is 10~20% of the total mass of DOPO and siloxane; wherein the active group in the graftable siloxane can be a Si-H bond or a Si-OH bond;

[0087] (2) Raise the temperature to 80~120℃ and reflux the reaction for 4~10 h;

[0088] (3) The solution obtained after the reaction is slowly poured into a rotary evaporator and distilled under reduced pressure at 80~120℃ for 2~4 h to finally prepare a new structure DOPO and its derivatives containing Si-O bonds.

[0089] The reactive polysiloxane described in component E has the following general structural formula (III):

[0090] (III)

[0091] Wherein, R1 and R2 are hydroxyl, amino or hydrogen, and R1 and R2 can be the same or different, preferably R1 and R2 are hydroxyl.

[0092] Preferably, the polysiloxane has an average molecular weight of 200-1000, corresponding to n being approximately 3-13, and the reactive polysiloxane is preferably... Silicon-containing flame retardants possess a stable Si-O-Si structure, exhibiting anti-dripping, char-forming, and smoke-suppressing properties. They can synergistically retard flames with DOPO and its derivatives, reducing the flammability of the coating on fabrics. Furthermore, they reduce the hydrophilicity introduced by DOPO and its derivatives on fabrics, thereby improving the water resistance of the coating.

[0093] In this invention, additive component F may optionally be added according to the product performance requirements. Preferably, the added component F is selected from two of hindered amines and hindered phenols for synergistic combination, and preferably a combination of antioxidant 1010 and light stabilizer 292.

[0094] Those skilled in the art will understand that a catalyst needs to be added during the prepolymerization reaction of isocyanate and polymer polyol. The catalyst is generally one of organotin, organobismuth or organozinc, preferably organobismuth catalyst, and the amount added is generally 100~500 ppm.

[0095] In this invention, the novel flame-retardant waterborne polyurethane dispersion has a solid content of 35-45 wt%, including but not limited to 35%, 36%, 37%, 38%, 39%, 40%, 41%, 2%, 3%, 44%, and 45%, preferably 38-42 wt%. The particle size of the dispersion is 20-200 nm, including but not limited to 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, and 200 nm, preferably 50-150 nm. The pH is 6-11, including but not limited to 6, 7, 8, 9, 10, and 11, preferably 6-9.

[0096] The method for preparing the dispersion of the present invention includes the following steps:

[0097] 1) Mix isocyanate A, polymer polyol B, hydrophilic compound C, DOPO or its derivative D, and reactive polysiloxane E in the above mass ratio and react them.

[0098] 2) In the reaction process of step 1), a catalyst of 100-300 ppm of the total weight of components A to E and 20-40% by weight of acetone need to be added; then, the reaction is carried out at 70-90℃ for a certain time until the theoretical NCO is reached, and diluted acetone is added to prepare the isocyanate-terminated prepolymer.

[0099] 3) Add acetone dilution of component F to the prepolymer, wherein the mass ratio of component F to acetone is 1:4, stir and mix evenly to obtain prepolymer G;

[0100] 4) Neutralize the prepolymer G with a neutralizing agent, wherein the molar ratio of the neutralizing agent to the hydrophilic compound C is (0.6~1):1, wherein the neutralizing agent is selected from alkali metal hydroxides or tertiary amines; preferably one of NaOH, KOH, triethylamine, and dimethylethanolamine;

[0101] 5) Add the product obtained in step 4) to deionized water accounting for 50% of the total solid weight for self-emulsification dispersion to obtain a crude emulsion of waterborne polyurethane dispersion. The temperature of the deionized water is controlled at 12~17℃, the dispersion time is 5~15min, and the preferred water addition time is 10min.

[0102] 6) The crude emulsion dispersed in step 5) is subjected to vacuum distillation at 45~60℃ to remove acetone and adjust to a theoretical solid content of 35~45wt%, thus obtaining a novel flame-retardant waterborne polyurethane dispersion.

[0103] The dispersion prepared by the above method can be used for fabric coatings, which can be used in fire suits, military uniforms, military tents, casual sportswear, sofas, seat cushions, postal parcels, protective equipment and medical supplies.

[0104] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0105] The testing method involved in this invention is as follows:

[0106] Solid content test method: Take an appropriate amount of emulsion in a container made of tin foil, place it in an oven at 150℃ for 20 min, weigh the change in mass, and calculate its solid content.

[0107] Infrared testing method: An ALPHA-C spectrometer from Bruker GmbH, Germany, was used.

[0108] Nuclear magnetic resonance testing method: AV400 nuclear magnetic resonance spectrometer.

[0109] Particle size testing method: Malvern particle size analyzer was used.

[0110] pH testing method: A pH meter is used.

[0111] Oxygen index testing shall be conducted in accordance with GB / T2406-1993 for limiting oxygen index testing.

[0112] Vertical burning test, conducted in accordance with GB / T2408-1996.

[0113] Hydrostatic pressure test shall be conducted in accordance with GB / T4744-1997.

[0114] Wash 5 times: According to GB / T8629-2001, the washing machine should wash 5 times at a water temperature of 40℃ for 45 minutes, and this process should be repeated 5 times. The water pressure drop should be less than 80% to be considered qualified.

[0115] The main sources of raw materials involved in the examples are as follows:

[0116] Dicyclohexylmethane diisocyanate (H) 12 MDI); Wanhua Chemical Group Co., Ltd., industrial products.

[0117] Hexamethylene diisocyanate (HDI): Wanhua Chemical Group Co., Ltd., industrial product.

[0118] Polybutylene adipate diol (PBA number-average molecular weight 2000), Wanhua Chemical Group Co., Ltd., industrial product.

[0119] Polytetrahydrofuran diol (PTMEG number-average molecular weight 2000), Wanhua Chemical Group Co., Ltd., industrial product.

[0120] Polybutylene adipate diol (PNA number average molecular weight 2000), Wanhua Chemical Group Co., Ltd., industrial product.

[0121] Polypropylene glycol (PPG number-average molecular weight 2000), Dongda Chemical, industrial product.

[0122] Dimethylolpropionic acid (DMPA), from Persto, Sweden, is an industrial product.

[0123] Catalyst: Organic bismuth 8108, from a leading US company, industrial product.

[0124] 292 (Light stabilizer, Ciba Corporation, USA).

[0125] 1010 (Antioxidant, Ciba Corporation, USA).

[0126] Triethylamine (TEA): Tianjin Kemio Chemical Reagent Co., Ltd., reagent.

[0127] DOPO (Flame Retardant): Aladdin Reagent (Shanghai) Co., Ltd., Reagent.

[0128] N-Aminoethylpiperazine: Aladdin Reagent (Shanghai) Co., Ltd., reagent.

[0129] Trimethoxy(6-(ethylene oxide-2-yl)hexyl)silane: Qingdao Xuxin Chemical Co., Ltd.

[0130] 1,3,3,3-Tetramethyldisiloxane-1-ol: Daejeon Chemical Additives Research Institute.

[0131] Polysiloxane (used in the examples): Wanhua Chemical Group Co., Ltd.

[0132] Vesmody ® U300 (Polyurethane Associative Thickener), Wanhua Chemical Group Co., Ltd.

[0133] Vesmody ® U605 (Polyurethane Associative Thickener), Wanhua Chemical Group Co., Ltd.

[0134] Aquolin ® 268 (isocyanate curing agent), Wanhua Chemical Group Co., Ltd.

[0135] Silok 43 (hand feel agent, Guangzhou Silok Chemical Co., Ltd.)

[0136] White paste (pigments and fillers, Jiangsu Fukenai Chemical Co., Ltd.)

[0137] Example 1

[0138] In a 500 ml three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple, 45.47 g of DOPO, 40.1 g of N-aminoethylpiperazine, and 10 g of toluene solvent were added sequentially, and the mixture was reacted at 100 °C for 6 h. After the reaction was completed, the resulting solution was distilled at 120 °C for 2 h to finally prepare DOPO and its derivatives (as shown in the figure below).

[0139]

[0140] Example 2

[0141] In a 500 ml three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple, 43.61 g of DOPO, 46.8 g of trimethoxy(6-(ethylene oxide-2-yl)hexyl)silane, and 18 g of toluene solvent were added sequentially, and the mixture was reacted at 80 °C for 4 h. After the reaction was completed, the resulting solution was distilled at 120 °C for 4 h to finally prepare DOPO and its derivatives containing a new Si-O structure (as shown in the figure below).

[0142]

[0143] Example 3

[0144] In a 500 ml three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple, 47.52 g of DOPO, 30 g of 1,3,3,3-tetramethyldisiloxane-1-ol, and 12 g of toluene solvent were added sequentially, and the mixture was reacted at 120 °C for 8 h. After the reaction was completed, the resulting solution was distilled at 120 °C for 4 h to finally prepare DOPO and its derivatives containing a new Si-O structure (as shown in the figure below).

[0145]

[0146] To verify the above products, Figure 1 FTIR spectra of the DOPO derivatives prepared in Examples 1-3 are shown. Several infrared peaks in the figures are assigned to the 3500-3300 cm⁻¹ region. -1 (NH), 1250cm -1 (P=O), 1050cm -1 (Si-O) and 880cm -1 Based on the stretching vibration peak of (PO), it can be preliminarily concluded that the DOPO derivatives of Examples 1, 2 and 3 were generated after the reaction.

[0147] To further verify this conclusion, 1 H-NMR has also been used to detect DOPO derivatives. Figure 2 The NMR spectrum of the DOPO derivative in Example 1 of this invention shows a new signal at 7.0-8.0 ppm, mainly attributed to the presence of the benzene ring in the DOPO derivative; the signals at 3.69 ppm and 1.07 ppm are primarily -NH- signals, while the signals at 2.34 ppm and 2.65 ppm are primarily -CH2- signals. Therefore, 1 H-NMR spectroscopy also indirectly confirmed the presence of DOPO derivatives.

[0148] same, Figure 3The NMR spectrum of the DOPO derivative prepared in Example 2 of this invention shows a new signal at 7.2-8.0 ppm, mainly attributed to the presence of the benzene ring in the DOPO derivative; the signal at 3.55 ppm is primarily a -OCH3 signal, while the signals at 1.25 ppm and 1.90 ppm are primarily -CH2 signals. Therefore, 1 H-NMR spectroscopy also indirectly confirmed the presence of DOPO derivatives.

[0149] Figure 4 The NMR spectrum of the DOPO derivative prepared in Example 3 of this invention shows a new signal appearing in the 7.25-8.0 ppm range, mainly attributed to the presence of the benzene ring in the DOPO derivative; the signal appearing in the 0.21 / 0.19 ppm range is primarily a -SiCH3 signal. Therefore, 1 H-NMR spectroscopy also indirectly confirmed the presence of DOPO derivatives.

[0150] Example 4

[0151] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, add 150 g PPG2000, 45.6 g PBA2000, 26.08 g DMPA, 32.6 g ordinary DOPO (as shown in the image below, Aladdin), 6.52 g polysiloxane (as shown in the image below), and 80 g H2O in sequence. 12 MDI, 50.4 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 3.41%. The temperature was then lowered to 30-35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0152]

[0153] 19.66 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 90 nm, and a pH of 7.8.

[0154] Example 5

[0155] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, add 150 g PPG2000, 45.6 g PBA2000, 45.64 g DMPA, 60.37 g DOPO derivative (see figure below, refer to Endo S, Kashihara T, Osako A, et al. Phosphorus-containing compounds[P]. US:4172 590, 1978-11-28. preparation), 2.6 g polysiloxane (see figure below), and 120 g H 12 MDI, 75.6 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 3.87%. The temperature was then lowered to 30-35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0156] 34.40 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 45 nm, and a pH of 8.0.

[0157]

[0158] Example 6

[0159] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, add 225 g PPG2000, 68.4 g PBA2000, 26.08 g DMPA, 43.77 g DOPO derivative (as shown in the figure below, refer to Liu CH, Wang C S. Novel phosphorus-containing epoxy resins Part I. Synthesis and properties[J]. Polymer, 2001, 41:1 869~1878. preparation), 3.12 g polysiloxane (as shown in the figure below), and 80 g H 12 MDI, 50.4 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 2.29%. The temperature was then lowered to 30-35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0160] 19.66 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 62 nm, and a pH of 7.6.

[0161]

[0162] Example 7

[0163] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, 175 g PPG2000, 53.4 g PBA2000, 39.12 g DMPA, 66.51 g a DOPO derivative (as shown in the figure below, prepared in Example 2), and 120 g H2O were added sequentially. 12 MDI, 75.6 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 5.38%. The temperature was then lowered to 30–35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0164] 29.48 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 53 nm, and a pH of 7.9.

[0165]

[0166] Example 8

[0167] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, 175 g PPG2000, 53.4 g PBA2000, 26.08 g DMPA, 47.54 g DOPO derivative (as shown in the figure below, prepared in Example 1), 3.12 g polysiloxane (as shown in the figure below), and 100 g H2O were added sequentially. 12 MDI, 63 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 3.86%. The temperature was then lowered to 30-35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0168]

[0169] 19.66 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 65 nm, and a pH of 7.4.

[0170] Example 9

[0171] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, 350 g PPG2000, 106.8 g PBA2000, 39.12 g DMPA, 79.5 g a DOPO derivative (prepared as shown in the figure below, Example 3), and 100 g H were added sequentially. 12 MDI, 63 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 1.14%. The temperature was then lowered to 30-35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0172] 29.48 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 49 nm, and a pH of 7.3.

[0173]

[0174] Example 10

[0175] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, 150 g PPG2000, 30 g PBA2000, 65.86 g DMPA, 30.185 g DOPO derivative (same as in Example 5), 2.6 g polysiloxane (same as in Example 5), 179 g H12MDI, and 37.8 g HDI were added sequentially, along with 300 ppm organobismuth catalyst and 150 g acetone solvent. The mixture was reacted at 80°C for 3 h to reach a theoretical NCO% of 3.25%, and then cooled to 30–35°C. A solution of 1010 and 292 acetones was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0176] 49.64 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 35 nm, and a pH of 8.3.

[0177] Example 11

[0178] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, 350 g PPG2000, 106.8 g PBA2000, 30 g DMPA, 35 g a DOPO derivative (same as in Example 9), and 65 g H were added sequentially. 12 MDI, 70g HDI, 300ppm organic bismuth catalyst, and 150g acetone solvent were added and reacted at 80℃ for 3 h to reach a theoretical NCO% of 1.67%. The temperature was then lowered to 30-35℃. A solution of 1010 and 292 acetones was added and stirred for 20 min to ensure homogeneity.

[0179] 22.61 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 75 nm, and a pH of 7.5.

[0180] Example 12

[0181] In a 2000 ml four-necked flask equipped with a stirrer, reflux condenser, and thermocouple, 100 g PPG2000, 128.4 g PBA2000, 39.12 g DMPA, 131.02 g a DOPO derivative (same as in Example 7), and 120 g H2O were added sequentially. 12 MDI, 75.6 g HDI, 300 ppm organic bismuth catalyst, and 150 g acetone solvent were added and reacted at 80 °C for 3 h to reach a theoretical NCO% of 4.11%. The temperature was then lowered to 30–35 °C. A solution of 1010 and 292 g acetone was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0182] 29.48 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 50 nm, and a pH of 7.9.

[0183] Comparative Example 1

[0184] The DOPO derivative in Example 6 was removed, while all other conditions remained the same.

[0185] The reaction was carried out at 80℃ for 3 h to reach the theoretical NCO% of 3.51%, and then the temperature was lowered to 30-35℃. An acetone solution of 1010 and 292 was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0186] 19.66 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 110 nm, and a pH of 8.1.

[0187] Comparative Example 2

[0188] The polysiloxane in Example 6 was removed, while other variables remained unchanged.

[0189] The reaction was carried out at 80℃ for 3 h to reach the theoretical NCO% of 2.40%, and then the temperature was lowered to 30-35℃. An acetone solution of 1010 and 292 was added, and the mixture was stirred for 20 min to ensure homogeneity.

[0190] 19.66 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 60 nm, and a pH of 7.5.

[0191] Comparative Example 3

[0192] The DOPO derivative and polysiloxane were removed from Example 6, while other variables remained unchanged.

[0193] The reaction was carried out at 80℃ for 3 h to reach the theoretical NCO% of 3.61%, and then the temperature was lowered to 30-35℃. An acetone solution of 1010 and 292 was added and stirred for 20 min to ensure uniform mixing.

[0194] 19.66 g of TEA was slowly added to the above mixture for neutralization. After neutralization for 10 min, 1000 g of water was added for emulsification. The resulting emulsion was distilled under reduced pressure to remove acetone and some water, yielding a water-permeable polyurethane emulsion with a solid content of 40 wt%, a particle size of 101 nm, and a pH of 7.9.

[0195] Performance testing

[0196] The construction process for preparing fabric coatings using the dispersions prepared in the examples and comparative examples is as follows:

[0197] Apply the sizing agent to a semi-matte nylon fabric using a round blade, and dry at 150℃ for 1 minute. Apply two coats, ensuring a total sizing amount of 20-30 g / m². 3 The samples were tested after being cured in a 50℃ oven for 24 hours.

[0198] The fabric coating application formula is as follows:

[0199] Waterborne polyurethane dispersion 90.5 Matrix resin <![CDATA[Aquolin ® 68]]> 2 Crosslinking agent Silok 43 0.5 feel agent White paste 5 Pigments and fillers <![CDATA[Vesmody ® 300]]> 1 Thickener <![CDATA[Vesmody ® 605]]> 1 Thickener

[0200] The performance test results of the aqueous polyurethane dispersions prepared in the above embodiments and comparative examples on fabric coatings are shown in the table below:

[0201] Oxygen Index / % 36 31 32 33 32 38 30 34 39 23 29 16 Vertical combustion V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-1 V-0 HB hydrostatic pressure drop rate / % 10% 18% 15% 20% 23% 14% 15% 13% 23% 16% 40% 27%

[0202] A comparison of the performance data of Comparative Example 1 and Example 6 shows that, compared with Example 6, the oxygen index of Comparative Example 1 decreased by 9%, and the vertical combustion performance differed by one level. This is mainly because the flame retardant in the comparative example does not contain DOPO derivatives, resulting in a significant decrease in flame retardant performance.

[0203] A comparison of the performance data of Comparative Example 2 and Example 6 shows that, compared to Example 6, the oxygen index of Comparative Example 1 decreased by 3%, and the flame retardant performance of the materials was similar at the same vertical burning level. However, the water resistance of the fabric coating decreased significantly, mainly because the coating does not contain hydrophobic polysiloxanes, and the large amount of DOPO derivatives introduced enhances the hydrophilicity of the material, resulting in a significant decrease in hydrostatic pressure.

[0204] A comparison of the performance data of Comparative Example 3 and Example 6 shows that, compared to Example 6, Comparative Example 3 has an oxygen index of only 16% and a vertical burning rating of HB, indicating poor flame retardancy and classifying it as a flammable material. This is mainly because the coating does not contain flame retardant DOPO derivatives or high-temperature resistant polysiloxanes.

[0205] A comparison of the performance data of Comparative Example 2 with those of Examples 7 and 9 shows that, compared to Examples 7 and 9, Comparative Example 2 has an oxygen index of 29% and a vertical burning rating of V-0, indicating essentially equivalent flame retardant performance. However, the hydrostatic pressure of Comparative Example 2 decreased by 40%, mainly due to the presence of DOPO derivatives with different flame retardant structures in the coating. Examples 7 and 9 involve adding a novel DOPO derivative flame retardant with PO and Si-O structures to prepare a highly efficient, flame-retardant waterborne polyurethane dispersion with excellent overall performance and broad application prospects.

[0206] A comparison of the performance data of Example 7 and Example 12 shows that by doubling the dosage of the novel flame retardant DOPO derivative, the oxygen index of Example 12 increased from 33% to 39%, its hydrostatic pressure decreased by 3%, the flame retardant performance was further improved, and the water resistance was less affected, thus meeting the usage requirements.

[0207] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A flame-retardant waterborne polyurethane dispersion, characterized in that, Based on the total mass of all components, the product is composed of the following components by mass percentage: A. At least two types of diisocyanates, 20-45 wt%; B. At least two polymeric polyols, 35-70 wt%; C. At least one hydrophilic compound, 3-15 wt%; D. At least one DOPO flame retardant, 5-25 wt%; E. Polysiloxanes with reactive functional groups, 0-3.0 wt%; F. Additives, wherein the amount of additives added is 0.2-2.0 wt% of the total weight of components A to E; The DOPO flame retardant in component D has a general structural formula of formula (I) or formula (II). When component D is formula (I), the mass percentage of polysiloxane with reactive functional groups in component E cannot be 0. (AND) (II) Wherein, R is selected from any one of straight-chain or branched hydrocarbon chains, optionally substituted carbocyclic rings, and optionally substituted heterocyclic rings, and X1 and X2 are sites that can react with isocyanates, each independently selected from hydroxyl and amino groups. W is selected from straight-chain or branched hydrocarbon chains or straight-chain or branched hydrocarbon chains containing N or O heteroatoms; Y1, Y2 and Y3 are sites that can react with isocyanates, each independently selected from hydrogen, hydroxyl, amino, straight-chain or branched hydrocarbon chains, and Y1, Y2 and Y3 are not simultaneously straight-chain or branched hydrocarbon chains. The preparation method of the flame-retardant waterborne polyurethane dispersion includes the following steps: 1) Mix and react components A, B, C, D and E in a certain ratio; the molar ratio of the NCO group in component A to the reactive groups in components B to E is (1.1~2):1; 2) Add catalyst and acetone during the reaction in step 1); then react at 70~90℃ until the theoretical NCO is reached, add acetone to dilute, and prepare the isocyanate-terminated prepolymer; 3) Add acetone dilution of component F to the prepolymer from step 2) and stir to mix evenly to obtain prepolymer G; 4) Neutralize prepolymer G with a neutralizing agent, wherein the molar ratio of the neutralizing agent to component C is (0.6~1):1; 5) Add water to the product obtained in step 4) and perform self-emulsification dispersion to obtain a crude emulsion of the waterborne polyurethane dispersion; 6) Remove acetone from the crude emulsion dispersed in step 5) and adjust it to the theoretical solid content to obtain a flame-retardant waterborne polyurethane dispersion.

2. The flame-retardant waterborne polyurethane dispersion according to claim 1, characterized in that, Based on the total mass of all components, the product is composed of the following components by mass percentage: A. At least two types of diisocyanates, 22-40 wt%; B. At least two polymeric polyols, 40-65 wt%; C. At least one hydrophilic compound, 5-10 wt%; D. At least one DOPO flame retardant, 8-20 wt%; E. 0-2.0 wt% of polysiloxanes with reactive functional groups; F. Additives, wherein the amount of additives added is 0.4-1.0 wt% of the total weight of components A to E; The sum of the mass percentages of the above components is 100%.

3. The flame-retardant waterborne polyurethane dispersion according to claim 1 or 2, characterized in that, Component A contains at least two diisocyanates, one of which is at least an aliphatic diisocyanate.

4. The flame-retardant waterborne polyurethane dispersion according to claim 3, characterized in that, The aliphatic diisocyanate is an alicyclic diisocyanate.

5. The flame-retardant waterborne polyurethane dispersion according to claim 4, characterized in that, The alicyclic diisocyanate is selected from any one of isoflurone diisocyanate, 1,4'-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 4,4'-dicyclohexylpropane diisocyanate.

6. The flame-retardant waterborne polyurethane dispersion according to claim 5, characterized in that, The at least two diisocyanates are 4,4'-dicyclohexylmethane diisocyanate and 1,6-hexyl diisocyanate, in a molar ratio of 1:

1.

7. The flame-retardant waterborne polyurethane dispersion according to claim 1 or 2, characterized in that, Component B contains at least two polymeric polyols, namely at least one polyester polyol and at least one polyether polyol.

8. The flame-retardant waterborne polyurethane dispersion according to claim 7, characterized in that, Component B contains at least two polymeric polyols, namely a polyester polyol with a number average molecular weight of 200-3000 and a polyether polyol with a number average molecular weight of 500-4000.

9. The flame-retardant waterborne polyurethane dispersion according to claim 8, characterized in that, The molar ratio of the at least one polyester polyol and the at least one polyether polyol is 1:3.

3.

10. The flame-retardant waterborne polyurethane dispersion according to claim 9, characterized in that, The polyester polyol is a polyester diol, selected from at least one of polybutylene adipate diol, polyethylene adipate diol, polypentylene adipate diol, polypentylene adipate hexanediol diol, polyhexanediol phthalate diol, polyethylene adipate diol, polycarbonate diol, or polycaprolactone diol; the polyether polyol is selected from at least one of polytetrahydrofuran diol, polypropylene diol, polyethylene glycol diol, and trihydroxypolyoxypropylene ether.

11. The flame-retardant waterborne polyurethane dispersion according to claim 1 or 2, characterized in that, The hydrophilic compound in component C is a dihydroxymethylalkyl acid.

12. The flame-retardant waterborne polyurethane dispersion according to claim 11, characterized in that, The hydrophilic compound in component C is dimethylolpropionic acid or dimethylolbutyric acid.

13. The flame-retardant waterborne polyurethane dispersion according to claim 1, characterized in that, When component D is of formula (I), the mass percentage of polysiloxane with reactive functional groups in component E is 0.2~2.0wt%; the carbide ring is selected from cycloalkyl, cycloalkenyl, aryl or fused carbide ring; the heterocycle includes one or more heteroatoms selected from O, S, N or Si.

14. The flame-retardant waterborne polyurethane dispersion according to claim 1, characterized in that, When component D is of formula (II), the mass ratio of polysiloxane with reactive functional groups in component E is 0-2.0 wt%.

15. The flame-retardant waterborne polyurethane dispersion according to claim 1, characterized in that, The DOPO flame retardant of formula (II) is prepared by the following steps: (1) Add a certain amount of DOPO, graftable siloxane and solvent to a three-necked flask; (2) Raise the temperature to 80~120℃ and reflux the reaction for 4~10 h; (3) The solution obtained after the reaction is subjected to vacuum distillation at 80~120℃ for 2~4 h to finally prepare the solution of formula ( DOPO flame retardants are of the general structural form.

16. The flame-retardant waterborne polyurethane dispersion according to claim 15, characterized in that, The graftable siloxane mentioned in step (1) is selected from any one of chlorinated siloxanes, siloxanes containing epoxy groups, and siloxanes containing hydroxyl groups.

17. The flame-retardant waterborne polyurethane dispersion according to claim 15, characterized in that, The molar ratio of the PH group in DOPO to the active group in the graftable siloxane is 1.05~1.1:

1.

18. The flame-retardant waterborne polyurethane dispersion according to claim 15, characterized in that, The solvent is selected from any one of benzene, toluene, tetrahydrofuran, acetone, and N,N-dimethylformamide; the solvent accounts for 10-20% of the total weight of DOPO and the graftable siloxane.

19. The flame-retardant waterborne polyurethane dispersion according to claim 1 or 2, characterized in that, The polysiloxane with reactive functional groups in component E has the general structural formula (III): (III) R1 and R2 are each independently selected from hydroxyl, amino, or hydrogen.

20. The flame-retardant waterborne polyurethane dispersion according to claim 19, characterized in that, The average molecular weight of the polysiloxane is 200-1000.

21. The flame-retardant waterborne polyurethane dispersion according to claim 1, characterized in that, The molar ratio of the NCO group in component A to the reactive groups in components B to E is (1.2~1.6):

1.

22. The flame-retardant waterborne polyurethane dispersion according to claim 1, characterized in that, The adjuvant is selected from two or more of antioxidants, light stabilizers, or ultraviolet absorbers.

23. The flame-retardant waterborne polyurethane dispersion according to claim 1 or 2, characterized in that, The neutralizing agent is selected from alkali metal hydroxides or tertiary amines.

24. The flame-retardant waterborne polyurethane dispersion according to claim 23, characterized in that, The neutralizing agent is any one of NaOH, KOH, triethylamine, and dimethylethanolamine.

25. The use of the flame-retardant waterborne polyurethane dispersion according to any one of claims 1-24 in fabric coatings.

26. The application according to claim 25, characterized in that, Applications in fabric coatings for fire suits, military uniforms, military tents, casual sportswear, sofas, seat cushions, postal parcels, and protective equipment.

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