A water-based polyurethane fire-retardant coating and its preparation method

Abstract

This invention relates to the field of polyurethane technology and discloses a waterborne polyurethane fire-retardant coating and its preparation method. A novel carboxyl-containing waterborne flame-retardant chain extender is prepared using pentaerythritol diphosphate bisphosphonate chloride, 4-methoxy-L-phenylalanine, and pyridine hydrochloride as reactants. This chain extender is then polymerized with diol and diisocyanate monomers to obtain the waterborne polyurethane fire-retardant coating. The waterborne polyurethane emulsion exhibits good dispersibility, high emulsion stability, and excellent hardness. Furthermore, the nitrogen-phosphorus flame-retardant structure of bisspirocyclic phosphoramide is grafted into the polyurethane molecular chain, significantly improving the limiting oxygen index of the polyurethane film material to 27.9-29.6%, achieving a UL-94 rating of V-0.

Description

Technical Field

[0001] This invention relates to the field of polyurethane technology, specifically to a water-based polyurethane fire-retardant coating and its preparation method. Background Technology

[0002] Water-based coatings contain no volatile organic solvents, are environmentally friendly, and have excellent film-forming properties. They are widely used in interior and exterior wall coatings, metal coatings, and automotive coatings. Among them, polyurethane water-based coatings have excellent mechanical properties and good elasticity, and are widely used. However, polyurethane water-based coatings have defects such as high water absorption, poor water resistance, and flammability, which limit their practical application in water-resistant and fire-retardant coatings.

[0003] Developing water-resistant waterborne polyurethane fire-retardant coatings is of great significance. Patent CN111574676B discloses the synthesis of a flame-retardant chain extender using hexachlorocyclotriphosphazene, 2,2-biphenylhydrazine, and hexamethylenediamine, which chemically bonds the flame retardant to the polyurethane molecular backbone, enhancing the thermal stability and flame retardancy of the waterborne polyurethane film. However, this patent additionally incorporates anionic waterborne chain extenders such as dimethylolpropionic acid and dimethylolbutyric acid. This invention prepares a novel waterborne flame-retardant chain extender, aiming to improve the water resistance, flame retardancy, and fire-retardant properties of waterborne polyurethane coatings. Summary of the Invention

[0004] Technical problem solved: This invention provides a water-based polyurethane fire-retardant coating with good water resistance.

[0005] Technical solution: A water-based polyurethane fire-retardant coating, comprising 100 parts by weight of diol, 42-68 parts by weight of diisocyanate monomer, 4-5 parts by weight of small molecule chain extender, 18-26 parts by weight of water-based flame-retardant chain extender, 0.12-0.16 parts by weight of dibutyltin dilaurate, 0.8-1.5 parts by weight of dispersant, 0.5-1 parts by weight of defoamer, 0.4-0.8 parts by weight of leveling agent, and 4-15 parts by weight of filler;

[0006] The structural formula of the water-based flame retardant chain extender is: .

[0007] The fillers include montmorillonite, talc, and vermiculite.

[0008] Furthermore, the diols include polyethylene glycol, polypropylene glycol, polycarbonate diol, and polytetrahydrofuran ether diol; the diisocyanate monomers include toluene-2,4-diisocyanate, 4,4-diphenylmethane diisocyanate, and isophorone diisocyanate; and the small molecule chain extender includes 1,4-butanediol.

[0009] Furthermore, the preparation method of the water-based flame retardant chain extender is as follows:

[0010] Step (1): Place the reactor in an ice-water bath, add the reaction solvent, 100 parts by weight of pentaerythritol diphosphate diphosphoyl chloride, 135-160 parts of 4-methoxy-L-phenylalanine, and 80-110 parts of N,N-diisopropylethylamine. After stirring, remove the ice-water bath, and after the reaction, rotary evaporate the mixture. Recrystallize dichloromethane to obtain the flame retardant intermediate.

[0011] Step (2): Add 100 parts of pyridine hydrochloride to a reactor equipped with a reflux condenser, heat to a molten state, add 7-10 parts of flame retardant intermediate, cool after reaction, add saturated sodium bicarbonate solution and dichloromethane, extract, remove the organic phase by drying, rotary evaporate, recrystallize the dichloromethane, and obtain the water-based flame retardant chain extender. Reaction route:

[0012]

[0013] Furthermore, the reaction solvents in step (1) include toluene, dichloromethane, and tetrahydrofuran.

[0014] Furthermore, the reaction in step (1) is carried out at a temperature of 25-40°C for 5-10 hours.

[0015] Furthermore, the reaction in step (2) is carried out at a temperature of 200-210°C for 2-4 hours.

[0016] Furthermore, the preparation method of waterborne polyurethane fire-retardant coating is characterized by: adding diol to a reactor, vacuum drying to remove water, introducing nitrogen gas, adding diisocyanate monomer, reacting at 70-80℃ for 2-3 hours, then adding waterborne flame retardant chain extender and dibutyltin dilaurate, reacting for 30-60 minutes, adding triethylamine for neutralization, adding water and small molecule chain extender, continuing the reaction for 20-40 minutes, and finally adding dispersant, defoamer, leveling agent and filler, stirring and dispersing to obtain waterborne polyurethane fire-retardant coating.

[0017] Beneficial technical effects: This invention utilizes pentaerythritol diphosphate diphosphoryl chloride, 4-methoxy-L-phenylalanine, pyridine hydrochloride, etc. as reactants to prepare a novel carboxyl-containing waterborne flame retardant chain extender, which is then polymerized with diol and diisocyanate monomers to obtain a waterborne polyurethane fireproof coating.

[0018] The polyurethane aqueous emulsion of the present invention has good dispersibility, high emulsion stability, and excellent hardness; at the same time, the nitrogen-phosphorus flame-retardant structure of bispirocyclophosphamide is grafted into the polyurethane molecular chain, which significantly improves the limiting oxygen index of the polyurethane film material to 27.9-29.6%, and the UL-94 rating reaches V-0. Detailed Implementation

[0019] The main raw materials of this invention are:

[0020] Pentaerythritol diphosphate diphosphonate, CAS No. 714-87-4, has the following structural formula: .

[0021] 4-Methoxy-L-phenylalanine: CAS No. 6230-11-1.

[0022] Dispersant: Model HY-6350.

[0023] Defoamer: Model XPJ55.

[0024] Leveling agent: Brand EFKA3777.

[0025] Example 1

[0026] The reactor was placed in an ice-water bath, and tetrahydrofuran solvent, 100 parts by weight of pentaerythritol diphosphophosphate diphosphoryl chloride, 160 parts by weight of 4-methoxy-L-phenylalanine, and 110 parts by weight of N,N-diisopropylethylamine were added. After stirring, the ice-water bath was removed, and the reaction was carried out at 30°C for 8 hours. The mixture was then rotary evaporated, and dichloromethane was recrystallized to obtain the flame retardant intermediate.

[0027] 100 parts of pyridine hydrochloride were added to a reactor containing a reflux condenser and heated to a molten state. 10 parts of flame retardant intermediate were added and reacted at 200°C for 2 hours. After cooling, saturated sodium bicarbonate solution and dichloromethane were added for extraction. The organic phase was dried and removed. The mixture was then rotary evaporated and the dichloromethane was recrystallized to obtain an aqueous flame retardant chain extender.

[0028] 100 parts by weight of polyethylene glycol were added to a reactor, vacuum dried to remove water, nitrogen gas was introduced, and 42 parts of toluene-2,4-diisocyanate were added. The mixture was reacted at 70°C for 3 hours. Then, 18 parts of water-based flame retardant chain extender and 0.13 parts of dibutyltin dilaurate were added, and the mixture was reacted for 60 minutes. Triethylamine was added for neutralization, followed by water and 4 parts of the small molecule chain extender 1,4-butanediol. The mixture was reacted for another 20 minutes. Finally, 0.8 parts of dispersant, 1 part of defoamer, 0.5 parts of leveling agent, and 4 parts of filler vermiculite powder were added, stirred and dispersed, and the total solid content of the emulsion was controlled to be 40% to obtain a water-based polyurethane fire-retardant coating.

[0029] Example 2

[0030] The reactor was placed in an ice-water bath, and toluene solvent, 100 parts by weight of pentaerythritol diphosphophosphate diphosphoryl chloride, 135 parts of 4-methoxy-L-phenylalanine, and 110 parts of N,N-diisopropylethylamine were added. After stirring, the ice-water bath was removed, and the reaction was carried out at 40°C for 5 hours. The mixture was then rotary evaporated, and dichloromethane was recrystallized to obtain the flame retardant intermediate.

[0031] 100 parts of pyridine hydrochloride were added to a reactor containing a reflux condenser and heated to a molten state. 8 parts of flame retardant intermediate were added and reacted at 210°C for 3 hours. After cooling, saturated sodium bicarbonate solution and dichloromethane were added for extraction. The organic phase was dried and removed, and the dichloromethane was recrystallized by rotary evaporation to obtain an aqueous flame retardant chain extender.

[0032] 100 parts by weight of polypropylene glycol were added to a reactor, vacuum dried to remove water, nitrogen gas was introduced, 68 parts of 4,4-diphenylmethane diisocyanate were added, and the mixture was reacted at 75°C for 2 hours. Then, 22 parts of water-based flame retardant chain extender and 0.16 parts of dibutyltin dilaurate were added, and the mixture was reacted for 30 minutes. Triethylamine was added for neutralization, followed by water and 4 parts of the small molecule chain extender 1,4-butanediol. The mixture was reacted for another 20 minutes. Finally, 1 part of dispersant, 1 part of defoamer, 0.4 parts of leveling agent, and 4 parts of filler vermiculite powder were added, and the mixture was stirred and dispersed. The total solid content of the emulsion was controlled to be 40%, thus obtaining a water-based polyurethane fire-retardant coating.

[0033] Example 3

[0034] The reactor was placed in an ice-water bath, and tetrahydrofuran solvent, 100 parts by weight of pentaerythritol diphosphophosphate diphosphoryl chloride, 135 parts of 4-methoxy-L-phenylalanine, and 102 parts of N,N-diisopropylethylamine were added. After stirring, the ice-water bath was removed, and the reaction was carried out at 30°C for 5 hours. The mixture was then rotary evaporated, and dichloromethane was recrystallized to obtain the flame retardant intermediate.

[0035] 100 parts of pyridine hydrochloride were added to a reactor containing a reflux condenser and heated to a molten state. 8 parts of flame retardant intermediate were added and reacted at 210°C for 2 hours. After cooling, saturated sodium bicarbonate solution and dichloromethane were added for extraction. The organic phase was dried and removed. The mixture was then rotary evaporated and the dichloromethane was recrystallized to obtain an aqueous flame retardant chain extender.

[0036] 100 parts by weight of polytetrahydrofuran ether diol were added to a reactor, vacuum dried to remove water, nitrogen gas was introduced, 64 parts of isophorone diisocyanate were added, and the reaction was carried out at 70°C for 3 hours. Then, 22 parts of water-based flame retardant chain extender and 0.16 parts of dibutyltin dilaurate were added, and the reaction was carried out for 60 minutes. Triethylamine was added for neutralization, water and 5 parts of small molecule chain extender 1,4-butanediol were added, and the reaction was continued for 40 minutes. Finally, 1 part of dispersant, 0.5 parts of defoamer, 0.6 parts of leveling agent and 15 parts of filler talc were added, stirred and dispersed, and the total solid content of the emulsion was controlled to be 40% to obtain water-based polyurethane fire-retardant coating.

[0037] Example 4

[0038] The reactor was placed in an ice-water bath, and dichloromethane, 100 parts by weight of pentaerythritol diphosphophosphate diphosphoryl chloride, 148 parts by weight of 4-methoxy-L-phenylalanine, and 102 parts by weight of N,N-diisopropylethylamine were added. After stirring, the ice-water bath was removed, and the reaction was carried out at 30°C for 8 hours. The mixture was then rotary evaporated, and the dichloromethane was recrystallized to obtain the flame retardant intermediate.

[0039] 100 parts of pyridine hydrochloride were added to a reactor containing a reflux condenser and heated to a molten state. 7 parts of flame retardant intermediate were added and reacted at 210°C for 2 hours. After cooling, saturated sodium bicarbonate solution and dichloromethane were added for extraction. The organic phase was dried and removed, and the dichloromethane was recrystallized by rotary evaporation to obtain an aqueous flame retardant chain extender.

[0040] 100 parts by weight of polycarbonate diol were added to a reactor, vacuum dried to remove water, nitrogen gas was introduced, and 42 parts of toluene-2,4-diisocyanate were added. The mixture was reacted at 75°C for 2 hours. Then, 26 parts of water-based flame retardant chain extender and 0.16 parts of dibutyltin dilaurate were added, and the mixture was reacted for 60 minutes. Triethylamine was added for neutralization, followed by water and 5 parts of the small molecule chain extender 1,4-butanediol. The mixture was reacted for another 20 minutes. Finally, 1 part of dispersant, 0.8 parts of defoamer, 0.8 parts of leveling agent, and 10 parts of filler montmorillonite were added, and the mixture was stirred and dispersed. The total solids content of the emulsion was controlled to be 40%, thus obtaining a water-based polyurethane fire-retardant coating.

[0041] Comparative Example 1

[0042] 100 parts by weight of polyethylene glycol were added to a reactor, vacuum dried to remove water, nitrogen gas was introduced, 42 parts of toluene-2,4-diisocyanate were added, and the mixture was reacted at 70°C for 3 hours. Then, 0.13 parts of dibutyltin dilaurate and 4 parts of the small molecule chain extender 1,4-butanediol were added, and the reaction was continued for 20 minutes. Finally, water, 0.8 parts of dispersant, 1 part of defoamer, 0.5 parts of leveling agent, and 4 parts of filler vermiculite powder were added, and the mixture was stirred and dispersed to obtain a polyurethane coating.

[0043] Stability test of polyurethane coating: The obtained waterborne polyurethane fire retardant coating was left to stand at 25℃ for 7-30 days to observe the stability of the waterborne emulsion.

[0044] Table 1 Stability of polyurethane aqueous emulsions

[0045]

[0046] Water-based polyurethane fire-retardant coating was poured onto a clean glass plate and dried at 60℃ for 12 hours to obtain a polyurethane film. The water resistance of the coating film was tested according to GB / T 1733-1993, and the pencil hardness was tested according to GB / T 6739-2006.

[0047]

[0048] Examples 1-4 use carboxyl groups. As a water-based flame retardant chain extender, polyurethane water-based emulsions exhibit good dispersibility, high emulsion stability, and excellent hardness.

[0049] The flame retardant properties of polyurethane membrane materials were tested according to GB / T 2406.1-2008 and UL-94 fire rating methods.

[0050]

[0051] In Examples 1-4, a water-based flame retardant chain extender was used to graft the nitrogen-phosphorus flame retardant structure of bispirocyclic phosphorus amide into the polyurethane molecular chain, which significantly improved the limiting oxygen index of the polyurethane film material to 27.9-29.6%, achieving a UL-94 rating of V-0.

[0052] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A water-based polyurethane fire-retardant coating, characterized in that: It includes 100 parts by weight of diol, 42-68 parts of diisocyanate monomer, 4-5 parts of small molecule chain extender, 18-26 parts of water-based flame retardant chain extender, 0.12-0.16 parts of dibutyltin dilaurate, 0.8-1.5 parts of dispersant, 0.5-1 part of defoamer, 0.4-0.8 parts of leveling agent, and 4-15 parts of filler; The structural formula of the water-based flame retardant chain extender is: ; The filler includes montmorillonite, talc powder, and vermiculite powder; The preparation method of the water-based flame retardant chain extender is as follows: Step (1): Place the reactor in an ice-water bath, add the reaction solvent, 100 parts by weight of pentaerythritol diphosphophosphate diphosphoryl chloride, 135-160 parts of 4-methoxy-L-phenylalanine, and 80-110 parts of N,N-diisopropylethylamine. After stirring, remove the ice-water bath, and after the reaction, rotary evaporate the mixture. Recrystallize the dichloromethane to obtain the flame retardant intermediate. Step (2): Add 100 parts of pyridine hydrochloride to a reactor containing a reflux condenser, heat to a molten state, add 7-10 parts of flame retardant intermediate, cool after reaction, add saturated sodium bicarbonate solution and dichloromethane, extract, dry the organic phase to remove it, rotary evaporate, recrystallize the dichloromethane to obtain the water-based flame retardant chain extender.

2. The water-based polyurethane fire-retardant coating according to claim 1, characterized in that: The diols include polyethylene glycol, polypropylene glycol, polycarbonate diol, and polytetrahydrofuran ether diol; the diisocyanate monomers include toluene-2,4-diisocyanate, 4,4-diphenylmethane diisocyanate, and isophorone diisocyanate; and the small molecule chain extender includes 1,4-butanediol.

3. The water-based polyurethane fire-retardant coating according to claim 1, characterized in that: The reaction solvents in step (1) include toluene, dichloromethane, and tetrahydrofuran.

4. The water-based polyurethane fire-retardant coating according to claim 1, characterized in that: The reaction in step (1) is carried out at a temperature of 25-40℃ for 5-10 hours.

5. The waterborne polyurethane fire-retardant coating according to claim 1, characterized in that: The reaction in step (2) is carried out at a temperature of 200-210℃ for 2-4 hours.

6. A method for preparing a waterborne polyurethane fire-retardant coating as described in any one of claims 1-5, characterized in that: Diol is added to a reactor, vacuum dried to remove water, nitrogen is introduced, diisocyanate monomer is added, and the reaction is carried out at 70-80℃ for 2-3 hours. Then, water-based flame retardant chain extender and dibutyltin dilaurate are added, and the reaction is carried out for 30-60 minutes. Triethylamine is added for neutralization, water and small molecule chain extender are added, and the reaction is continued for 20-40 minutes. Finally, dispersant, defoamer, leveling agent and filler are added, and the mixture is stirred and dispersed to obtain water-based polyurethane fireproof coating.

Images