Preparation method and application of an aqueous two-component polyurethane flame retardant material

Abstract

The invention discloses a preparation method and application of a waterborne two-component polyurethane flame retardant material, which comprises the following steps: S1: synthesis of a waterborne hydroxypropyl dispersion; S2: synthesis of a waterborne polyurethane curing agent; S3: preparing the synthesized waterborne hydroxypropyl dispersion into a varnish or a colored paint, and uniformly mixing the obtained varnish or colored paint with the waterborne polyurethane curing agent to obtain the product. The paint film obtained by spraying and film forming has a smooth and flawless surface, good fullness, high gloss, high hardness, good water resistance, can be extinguished immediately when removed from the fire, has excellent flame retardant performance, and can be widely applied to the fields that need to be coated with a flame retardant coating.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant coatings, in particular to the IPC C08 field, and more specifically, to a preparation method and application of a waterborne two-component polyurethane flame retardant material. Background Art

[0002] Solvent-based flame retardant coatings have good mechanical properties and chemical corrosion resistance, and have been rapidly developed and applied in the past few decades. Among them, waterborne flame retardant coatings use water as a solvent, are non-toxic and harmless to the environment after drying, and the formed paint films have excellent mechanical properties and chemical properties, making them one of the main directions for the development of flame retardant coatings. Waterborne coatings include single-component and two-component waterborne coatings. The single-component coatings have low film hardness, poor water resistance and flame retardant performance, and their applications are limited. Among the two-component coatings, two-component waterborne polyurethane flame retardant coatings have excellent physical and chemical properties and excellent flame retardant performance.

[0003] CN 101768250 provides a highly flame retardant polyurethane composition and its preparation method. The highly flame retardant polyurethane composition consists of component A and component B. Component A is composed of polyether polyol, flame retardant polyether polyol, crosslinking agent, foam stabilizer, water, physical foaming agent and catalyst; component B is composed of polyether polyol, flame retardant, polymeric MDI and toluene diisocyanate prepolymer. When in use, components A and B are mixed evenly according to the mass ratio of A:B = 100:50 - 60, and then injected into a mold with a mold temperature of 45 - 65°C. After 5 - 10 minutes, the mold is opened and left at room temperature for 24 hours. The oxygen index of the highly flame retardant polyurethane composition prepared by this invention is ≥32, and it has advantages such as good fluidity and high storage stability, which is very convenient for the use and storage of foam manufacturers, but the flame retardant performance of the paint film and the hardness of the paint film are insufficient. Summary of the Invention

[0004] In order to solve the above problems, the first aspect of the present invention provides a preparation method of a waterborne two-component polyurethane flame retardant material, including the following steps:

[0005] S1: Synthesis of waterborne hydroxypropyl dispersion;

[0006] S2: Synthesis of waterborne polyurethane curing agent;

[0007] S3: The synthesized waterborne hydroxypropyl dispersion is made into a varnish or a colored paint, and the obtained varnish or colored paint and the waterborne polyurethane curing agent are mixed evenly to obtain the product.

[0008] Preferably, the specific steps of S1 are as follows: Mix the organic acid, hard monomer, soft monomer, bifunctional monomer, and acrylic acid phosphate evenly to obtain a mixed monomer; heat the solvent to 130-150 °C, and at the same time, drop the mixed monomer and initiator into the solvent, and finish dropping the mixed monomer in 4-8 h; then use the first neutralizing agent for neutralization and cool down to 75-85 °C, add water and stir evenly to obtain an aqueous hydroxypropyl dispersion.

[0009] Preferably, the mass ratio of the organic acid, hard monomer, soft monomer, bifunctional monomer, and acrylic acid phosphate is (2-3):(12-18):(10-15):(6-13):(5-10).

[0010] Preferably, the initiator is at least one of di-tert-amyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, and tert-butyl peroxyoctanoate.

[0011] Preferably, the initiator is di-tert-amyl peroxide.

[0012] Preferably, the organic acid is at least one of acrylic acid, methacrylic acid, and carboxyethyl acrylate.

[0013] Preferably, the organic acid is acrylic acid.

[0014] Preferably, the hard monomer is at least one of methyl methacrylate, styrene, vinyl acetate, acrylonitrile, isobornyl acrylate, and cyclohexyl acrylate.

[0015] Preferably, the hard monomer is methyl methacrylate and isobornyl methacrylate.

[0016] Preferably, the soft monomer is at least one of butyl acrylate, ethyl acrylate, butyl methacrylate, isooctyl acrylate, and tert-butyl acrylate.

[0017] Preferably, the soft monomer is butyl acrylate.

[0018] Preferably, the bifunctional monomer is at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate.

[0019] Preferably, the bifunctional monomer is 2-hydroxypropyl acrylate.

[0020] Preferably, the acrylic acid phosphate is at least one of diethyl methylphosphonate acrylate, diethyl ethylphosphonate acrylate, dimethyl ethylphosphonate acrylate, dimethyl methylphosphonate methacrylate, 2-hydroxyethyl methacrylate phosphate, and ethylene glycol methacrylate phosphate.

[0021] Preferably, the acrylic phosphate is diethyl methylphosphonate acrylate and diethyl ethylphosphonate acrylate.

[0022] Preferably, the solvent is at least one of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, tripropylene glycol monomethyl ether, and dipropylene glycol n-propyl ether.

[0023] Preferably, the solvent is ethylene glycol monobutyl ether.

[0024] Preferably, the first neutralizing agent is at least one of dimethylethanolamine, diethanolamine, triethanolamine, and triethylamine.

[0025] Preferably, the first neutralizing agent is dimethylethanolamine.

[0026] Preferably, the specific steps of S1 are as follows: Mix 2-3 parts by weight of organic acid, 12-18 parts by weight of hard monomer, 10-15 parts by weight of soft monomer, 6-13 parts by weight of difunctional monomer, and 5-10 parts by weight of acrylic phosphate evenly to obtain a mixed monomer; Heat 4-8 parts by weight of the solvent to 130-150 °C, and simultaneously dropwise add the mixed monomer and 0.5-1.5 parts by weight of initiator into the solvent, and finish dropping the mixed monomer in 4-8 h; Then neutralize with 1-3 parts of the first neutralizing agent and cool down to 75-85 °C, add 44-55 parts by weight of water and stir evenly to obtain an aqueous hydroxypropyl dispersion.

[0027] Preferably, the modification amount of the aqueous hydroxypropyl dispersion is 5-10%, the solid content is 40-50%, and the hydroxyl content is 2-4.5%.

[0028] The modification amount of the aqueous hydroxypropyl dispersion is the mass ratio of acrylic phosphate in the raw materials for preparing the aqueous hydroxypropyl dispersion.

[0029] Preferably, the specific steps of S2 are as follows: Heat the isocyanate trimer to 80-120 °C, add solid acid, keep warm for 1-5 h, then add the second neutralizing agent for neutralization and cool down to 65-75 °C, and then add phosphorus-containing polyether, keep warm for 1-3 h and then cool down to obtain an aqueous polyurethane curing agent.

[0030] Preferably, the specific steps of S2 are as follows: Heat 70-85 parts by weight of isocyanate trimer to 80-120 °C, add 3-8 parts by weight of solid acid, keep warm for 1-5 h, then add 1-5 parts by weight of the second neutralizing agent for neutralization and cool down to 65-75 °C, and then add 10-15 parts of phosphorus-containing polyether, keep warm for 1-3 h and then cool down to obtain an aqueous polyurethane curing agent.

[0031] Preferably, the isocyanate trimer is at least one of hexamethylene diisocyanate trimer, isophorone diisocyanate trimer, hexamethylene diisocyanate-toluene diisocyanate trimer, xylylene diisocyanate trimer, hexamethylene diisocyanate-trimethyl phosphate adduct, diphenylmethane diisocyanate trimer, and toluene diisocyanate trimer.

[0032] Preferably, the second neutralizing agent is at least one of dimethylethanolamine, diethanolamine, triethanolamine, and triethylamine.

[0033] Preferably, the second neutralizing agent is dimethylethanolamine.

[0034] Preferably, the solid acid is at least one of hydroxycarboxylic acid, aminosulfonic acid, periodic acid, and trichloroacetic acid.

[0035] Preferably, the solid acid is aminosulfonic acid.

[0036] Preferably, the modification amount of the aqueous polyurethane curing agent is 10-15%.

[0037] The modification amount of the aqueous polyurethane curing agent is the mass ratio of the phosphorus-containing polyether in the raw materials for preparing the aqueous polyurethane curing agent.

[0038] In this application, by using an acrylic phosphate modification amount of 5-10% of the aqueous hydroxypropyl dispersion, the flame retardancy and water resistance of the aqueous hydroxypropyl dispersion can be effectively improved. During the synthesis process of the aqueous hydroxypropyl dispersion, carboxyl groups are introduced, and a neutralizing agent is added to form salts to achieve the effect of making the hydroxypropyl dispersion water-based. However, in a high-humidity environment, due to the strong association between carboxyl groups and water, the water resistance of the aqueous hydroxypropyl dispersion is significantly reduced in a high-humidity environment. Through the modification with acrylic phosphate, a three-dimensional network structure is formed by cross-linking between groups, enhancing the water resistance and mechanical properties of the aqueous hydroxypropyl dispersion. In addition, since the phosphate ester can form a dense carbon layer by dehydration during combustion, covering the surface of the material to play a role in heat insulation and oxygen isolation, and a large amount of phosphorus remains in the carbon layer to further improve the thermal stability of the carbon layer. The highly dense and stable carbon layer formed can effectively prevent oxygen from entering the interior of the material and also prevent the combustible volatiles under the carbon layer from entering the air, thereby improving the flame retardancy of the aqueous hydroxypropyl dispersion.

[0039] Preferably, the specific steps of S3 are as follows: 1) Prepare varnish: Place the synthesized aqueous hydroxypropyl dispersion in a container and disperse it at 800-1000 r / min, add an antifoaming agent and disperse for 4-6 min, add a wetting agent and a leveling agent and disperse for 4-6 min, add a film-forming aid, disperse with water for 5-15 min, add a thickening agent and disperse evenly to obtain varnish; 2) Mix the varnish and the aqueous polyurethane curing agent evenly to obtain the flame retardant material.

[0040] Preferably, in the step S3, the mass ratio of the aqueous hydroxypropyl dispersion to the aqueous polyurethane curing agent is (3-8):1.

[0041] An application of the preparation method of the aqueous two-component polyurethane flame retardant material as described above for preparing a flame retardant coating.

[0042] Beneficial effects:

[0043] 1. The present invention provides an aqueous two-component polyurethane flame retardant material. The paint film obtained by spraying and forming a film has a smooth and flawless surface, good fullness, high gloss, high hardness, good water resistance, can achieve immediate extinguishment when leaving the fire, has excellent flame retardant performance, and can be widely applied to fields that require a flame retardant coating.

[0044] 2. In the synthesis of the aqueous polyurethane curing agent in this application, the modification amount of the phosphorus-containing polyether is 10-15%. By controlling the phosphorus content in the synthesized aqueous polyurethane curing agent molecule, phosphorus will catalyze the rapid formation of a carbon layer during combustion, increase the carbon residue amount of the coating film at high temperature, and thus improve the flame retardant performance of the prepared flame retardant material.

[0045] 3. In this application, by using 8% of the acrylic acid phosphate modification amount of the aqueous hydroxypropyl dispersion, crosslinking between groups forms a three-dimensional network structure, enhancing the water resistance and mechanical properties of the aqueous hydroxypropyl dispersion. At the same time, the phosphate ester can form a dense carbon layer through dehydration during combustion, covering the surface of the material to play a role in heat insulation and oxygen isolation, thereby improving the flame retardant performance of the aqueous hydroxypropyl dispersion.

[0046] 4. In this application, by synthesizing the aqueous hydroxypropyl dispersion and the aqueous polyurethane curing agent, formulating the synthesized aqueous hydroxypropyl dispersion into a varnish or colored paint, and then combining it with the synthesized aqueous polyurethane curing agent in this application to obtain a flame retardant coating can achieve an excellent flame retardant effect, and the surface effect, water resistance, and mechanical properties of the coating are excellent. Using the synthesized aqueous hydroxypropyl dispersion in this application alone with other ordinary curing agents or using the synthesized aqueous polyurethane curing agent in this application alone with other ordinary hydroxypropyl dispersions cannot obtain the same excellent flame retardant effect as this application. Specific embodiments

[0047] Examples

[0048] Example 1:

[0049] Example 1 provides a preparation method of an aqueous two-component polyurethane flame retardant material, including the following steps:

[0050] S1: Synthesis of aqueous hydroxypropyl dispersion: Mix 2.5 parts by weight of organic acid, 15 parts by weight of hard monomer, 12 parts by weight of soft monomer, 8 parts by weight of bifunctional monomer, and 8 parts by weight of acrylic acid phosphate to obtain a mixed monomer; Heat 5 parts by weight of solvent to 140 °C, and simultaneously add the mixed monomer and 1 part by weight of initiator dropwise to the solvent, and finish dropping the mixed monomer in 6 h; Then neutralize with 2.5 parts of the first neutralizer and cool to 80 °C, add 46 parts by weight of water and stir evenly to obtain an aqueous hydroxypropyl dispersion.

[0051] S2: Synthesis of aqueous polyurethane curing agent: Heat 81 parts by weight of isocyanate trimer to 100 °C, add 5 parts by weight of solid acid, keep warm for 3 h, then add 2 parts by weight of the second neutralizer for neutralization and cool to 70 °C, then add 12 parts of phosphorus-containing polyether, keep warm for 2 h and then cool to 25 °C to obtain an aqueous polyurethane curing agent.

[0052] S3: Place 84 parts by weight of the synthesized aqueous hydroxypropyl dispersion in a container and disperse at 1000 r / min, add 0.3 parts by weight of defoaming agent and disperse for 5 min, add 0.3 parts by weight of wetting agent and 0.2 parts by weight of leveling agent and disperse for 5 min, add 6 parts by weight of film-forming aid and 8.9 parts by weight of water and disperse for 10 min, add 0.3 parts by weight of thickener and disperse evenly to obtain varnish; 2) Mix the varnish and the aqueous polyurethane curing agent evenly, and the mass ratio of the two is 5:1 to obtain a flame retardant material.

[0053] The organic acid is acrylic acid;

[0054] The hard monomer is methyl methacrylate and isobornyl methacrylate, and the mass ratio of methyl methacrylate to isobornyl methacrylate is 1:2;

[0055] The soft monomer is butyl acrylate;

[0056] The bifunctional monomer is hydroxypropyl acrylate;

[0057] The acrylic acid phosphate is diethyl methylphosphonate acrylate and diethyl ethylphosphonate acrylate, and the mass ratio of diethyl methylphosphonate acrylate to diethyl ethylphosphonate acrylate is 1:1;

[0058] The solvent is ethylene glycol monobutyl ether;

[0059] The first neutralizer is dimethylethanolamine;

[0060] The isocyanate trimer is hexamethylene diisocyanate trimer;

[0061] The second neutralizer is dimethylethanolamine;

[0062] The solid acid is sulfamic acid;

[0063] The mixing weight ratio of the synthesized aqueous hydroxypropyl dispersion to the aqueous polyurethane curing agent is 5:1.

[0064] The modification amount of the synthesized aqueous hydroxypropyl dispersion is 8%, the solid content is 46.5%, and the hydroxyl content is 2.25%

[0065] The modification amount of the synthesized aqueous polyurethane curing agent is 12%, and the isocyanate group content is 15.1%.

[0066] The phosphorus-containing polyether is polypropylene glycol phosphate.

[0067] Dimethylethanolamine is purchased from BASF.

[0068] Hexamethylene diisocyanate trimer is purchased from BASF, model HI100.

[0069] The defoaming agent is Xianchuang 561PL defoaming agent, purchased from SYNTHRON (Xianchuang) Chemicals Company, France.

[0070] The wetting agent is Degussa TEGO270, and the leveling agent is Degussa TEGO450, purchased from Degussa TEGO Company, Germany.

[0071] The film-forming aid is dipropylene glycol methyl ether and dipropylene glycol butyl ether, and the weight ratio of dipropylene glycol methyl ether to dipropylene glycol butyl ether is 1:1, purchased from Dow Chemical Company.

[0072] Example 2

[0073] Example 2 provides a preparation method of a waterborne two-component polyurethane flame retardant material. The specific implementation method is the same as that of Example 1, except that in step S1: synthesis of the aqueous hydroxypropyl dispersion: 3 parts by weight of organic acid, 13 parts by weight of hard monomer, 10 parts by weight of soft monomer, 12 parts by weight of bifunctional monomer, and 9 parts by weight of acrylic acid phosphate are mixed evenly to obtain a mixed monomer; 5 parts by weight of solvent is heated to 140 °C, and at the same time, the mixed monomer and 1 part by weight of initiator are added dropwise to the solvent, and the mixed monomer is added dropwise within 6 h; then 2.5 parts of the first neutralizing agent is used for neutralization and then cooled to 80 °C, and 44.5 parts by weight of water is added and stirred evenly to obtain the aqueous hydroxypropyl dispersion.

[0074] In step S3 2), the varnish and the aqueous polyurethane curing agent are mixed evenly, and the mass ratio of the two is 3.5:1.

[0075] The modification amount of the synthesized aqueous hydroxypropyl dispersion is 9%, the solid content is 48%, and the hydroxyl content is 3.27%.

[0076] Comparative Example 1

[0077] Comparative Example 1 provided a preparation method of a waterborne two-component polyurethane flame retardant material. The specific implementation was the same as that of Example 1, except that a waterborne resin XJ-303H purchased from Guangzhou Biheng Chemical Technology Co., Ltd. was mixed evenly with the synthesized waterborne polyurethane curing agent at a weight ratio of 5:1 to obtain the flame retardant material.

[0078] Comparative Example 2

[0079] Comparative Example 2 provided a preparation method of a waterborne two-component polyurethane flame retardant material. The specific implementation was the same as that of Example 1, except that the synthesized waterborne hydroxypropyl dispersion was diluted to the same isocyanate content as in the example with a waterborne polyurethane curing agent 2655 purchased from Covestro Germany and mixed evenly at a weight ratio of 5:1 to obtain the flame retardant material.

[0080] Comparative Example 3:

[0081] Comparative Example 3 provided a preparation method of a waterborne two-component polyurethane flame retardant material. The specific implementation was the same as that of Example 1, except that a waterborne resin XJ-303H purchased from Guangzhou Biheng Chemical Technology Co., Ltd. was diluted to the same isocyanate content as in the example with a waterborne polyurethane curing agent 2655 purchased from Covestro Germany and mixed evenly at a weight ratio of 5:1 to obtain the flame retardant material.

[0082] Comparative Example 4

[0083] Comparative Example 4 provided a preparation method of a waterborne two-component polyurethane flame retardant material. The specific implementation was the same as that of Example 1, except that in step S1: synthesis of the waterborne hydroxypropyl dispersion: 2.5 parts by weight of organic acid, 11 parts by weight of hard monomer, 11 parts by weight of soft monomer, 8 parts by weight of bifunctional monomer, and 15 parts by weight of acrylic acid phosphate were mixed evenly to obtain a mixed monomer; 5 parts by weight of solvent was heated to 140 °C, and at the same time, the mixed monomer and 1 part by weight of initiator were added dropwise to the solvent, and the mixed monomer was added dropwise in 6 h; then it was neutralized with 2.5 parts of the first neutralizer and cooled to 80 °C, and 39 parts by weight of water was added and stirred evenly to obtain the waterborne hydroxypropyl dispersion.

[0084] The modification amount of the synthesized waterborne hydroxypropyl dispersion was 15%, the solid content was 48.5%, and the hydroxyl content was 2.5%.

[0085] Comparative Example 5

[0086] Comparative Example 5 provides a method for preparing an aqueous two-component polyurethane flame retardant material. The specific implementation is the same as that of Example 1, except that in step S1: synthesis of the aqueous hydroxypropyl dispersion: 3 parts by weight of organic acid, 18 parts by weight of hard monomer, 15 parts by weight of soft monomer, 8.5 parts by weight of bifunctional monomer, and 3 parts by weight of acrylic acid phosphate are mixed evenly to obtain a mixed monomer; 5 parts by weight of solvent is heated to 140 °C, and at the same time, the mixed monomer and 1 part by weight of initiator are added dropwise to the solvent, and the mixed monomer is added dropwise within 6 h; then 2.5 parts of the first neutralizing agent is used for neutralization, and then the temperature is lowered to 80 °C, and 51 parts by weight of water is added and stirred evenly to obtain the aqueous hydroxypropyl dispersion,

[0087] The modification amount of the synthesized aqueous hydroxypropyl dispersion is 3%, the solid content is 48.5%, and the hydroxyl content is 2.28%.

[0088] Comparative Example 6

[0089] Comparative Example 6 provides a method for preparing an aqueous two-component polyurethane flame retardant material. The specific implementation is the same as that of Example 1, except that in step S2: synthesis of the aqueous polyurethane curing agent: 78 parts by weight of isocyanate trimer is heated to 100 °C, 6 parts by weight of solid acid is added, and the temperature is kept for 3 h, then 4 parts by weight of the second neutralizing agent is added for neutralization, and then the temperature is lowered to 70 °C, and 20 parts of phosphorus-containing polyether is added, and after keeping the temperature for 2 h, the temperature is lowered to 25 °C to obtain the aqueous polyurethane curing agent.

[0090] In step S3 2), the varnish and the aqueous polyurethane curing agent are mixed evenly, and the mass ratio of the two is 5:1.1.

[0091] The modification amount of the synthesized aqueous polyurethane curing agent is 20%, and the isocyanate group content is 13.5%.

[0092] Comparative Example 7

[0093] Comparative Example 7 provides a method for preparing an aqueous two-component polyurethane flame retardant material. The specific implementation is the same as that of Example 1, except that in step S2: synthesis of the aqueous polyurethane curing agent: 85 parts by weight of isocyanate trimer is heated to 100 °C, 6 parts by weight of solid acid is added, and the temperature is kept for 3 h, then 4 parts by weight of the second neutralizing agent is added for neutralization, and then the temperature is lowered to 70 °C, and 5 parts of phosphorus-containing polyether is added, and after keeping the temperature for 2 h, the temperature is lowered to 25 °C to obtain the aqueous polyurethane curing agent.

[0094] In step S3 2), the varnish and the aqueous polyurethane curing agent are mixed evenly, and the mass ratio of the two is 5:0.91.

[0095] The modification amount of the synthesized aqueous polyurethane curing agent is 5%, and the isocyanate group content is 16.5%.

[0096] Performance test:

[0097] The uniformly mixed flame retardant materials obtained in Examples 1-2 and Comparative Examples 1-7 were sprayed onto

[0098] 1. Film hardness: The hardness of the 30-μm-thick films uniformly sprayed with the flame retardant materials obtained in Examples 1-2 and Comparative Examples 1-7 was tested using the pencil method for film hardness determination in GB / T 6739-2006, and the average value of the measured results was recorded in Table 1.

[0099] 2. Film glossiness: The glossiness of the 30-μm-thick films uniformly sprayed with the flame retardant materials obtained in Examples 1-2 and Comparative Examples 1-7 was tested using the method for film glossiness determination in GB / T 1743-1979, and the average value of the measured results was recorded in Table 1.

[0100] 3. Flame retardancy: The flame retardancy of the 30-μm-thick films uniformly sprayed with the flame retardant materials obtained in Examples 1-2 and Comparative Examples 1-7 was tested using "Plastics - Determination of flammability - Horizontal and vertical methods" in GB / T 2408-2008, and the average value of the measured results was recorded in Table 1.

[0101] 4. Water resistance: The water resistance of the 30-μm-thick films uniformly sprayed with the flame retardant materials obtained in Examples 1-2 and Comparative Examples 1-7 was tested using the method for film water resistance determination in GB / T 1733-93. The films were soaked at 25°C for 10 days, and the average value of the measured results was recorded in Table 1.

[0102] Table 1

[0103]

[0104]

Claims

1. A preparation method of an aqueous two-component polyurethane flame retardant material, characterized in that, It includes the following steps: S1: Synthesis of aqueous hydroxypropyl dispersion; S2: Synthesis of aqueous polyurethane curing agent; S3: Making the synthesized aqueous hydroxypropyl dispersion into varnish or colored paint, and mixing the obtained varnish or colored paint and the aqueous polyurethane curing agent evenly to obtain the product; The specific steps of S1 are: mixing organic acid, hard monomer, soft monomer, bifunctional monomer, and acrylic acid phosphate evenly to obtain a mixed monomer; heating the solvent to 130 - 150 °C, and simultaneously dropping the mixed monomer and initiator into the solvent, and finishing dropping the mixed monomer in 4 - 8 h; then using the first neutralizing agent for neutralization and cooling to 75 - 85 °C, adding water and stirring evenly to obtain the aqueous hydroxypropyl dispersion; The mass ratio of the organic acid, hard monomer, soft monomer, bifunctional monomer, and acrylic acid phosphate is (2 - 3):(12 - 18):(10 - 15):(6 - 13):(5 - 10); The specific steps of S2 are: heating the isocyanate trimer to 80 - 120 °C, adding solid acid, keeping warm for 1 - 5 h, then using the second neutralizing agent for neutralization and cooling to 65 - 75 °C, and then adding phosphorus-containing polyether, keeping warm for 1 - 3 h and then cooling to obtain the aqueous polyurethane curing agent; The modification amount of the aqueous hydroxypropyl dispersion is 5 - 10%, the solid content is 40 - 50%, and the hydroxyl content is 2 - 4.5%; The modification amount of the aqueous polyurethane curing agent is 10 - 15%, and the modification amount of the aqueous polyurethane curing agent is the mass ratio of phosphorus-containing polyether in the raw materials for preparing the aqueous polyurethane curing agent; The phosphorus-containing polyether is polypropylene glycol phosphate; The solvent is at least one of ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, tripropylene glycol monomethyl ether, and dipropylene glycol propyl ether; The modification amount of the aqueous hydroxypropyl dispersion is the mass ratio of acrylic acid phosphate in the raw materials for preparing the aqueous hydroxypropyl dispersion; The hard monomer is at least one of methyl methacrylate, styrene, vinyl acetate, acrylonitrile, isobornyl acrylate, and cyclohexyl acrylate; The soft monomer is at least one of butyl acrylate, ethyl acrylate, butyl methacrylate, isooctyl acrylate, and tert-butyl acrylate; The bifunctional monomer is at least one of 2-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate; The solid acid is at least one of sulfamic acid, periodic acid, and trichloroacetic acid; The first neutralizing agent is dimethylethanolamine; the second neutralizing agent is dimethylethanolamine.

2. The preparation method of the aqueous two-component polyurethane flame retardant material according to claim 1, characterized in that, The initiator is at least one of di-tert-amyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, and tert-butyl peroxyisobutyrate; 3. The preparation method of the waterborne two-component polyurethane flame retardant material according to claim 1, characterized in that, The isocyanate trimer is at least one of hexamethylene diisocyanate trimer, isophorone diisocyanate trimer, hexamethylene diisocyanate - toluene diisocyanate trimer, xylylene diisocyanate trimer, diphenylmethane diisocyanate trimer, and toluene diisocyanate trimer.

4. The preparation method of the aqueous two-component polyurethane flame retardant material according to claim 1, characterized in that, The specific steps of S3 are as follows: 1) Prepare varnish: Place the synthesized aqueous hydroxypropyl dispersion in a container and disperse it at 800 - 1000 r / min. Add an antifoaming agent and disperse for 4 - 6 min, then add a wetting agent and a leveling agent and disperse for 4 - 6 min. Add a film-forming aid and disperse with water for 5 - 15 min, and then add a thickening agent and disperse evenly to obtain the varnish; 2) Mix the varnish and the aqueous polyurethane curing agent evenly to obtain the flame retardant material.

5. The preparation method of the aqueous two-component polyurethane flame retardant material according to claim 4, characterized in that, The mass ratio of the aqueous hydroxypropyl dispersion to the aqueous polyurethane curing agent is (3 - 8):

1.

6. Use of a preparation method of the waterborne two-component polyurethane flame retardant material according to any one of claims 1 to 5, characterized in that, It is used for preparing a flame retardant coating.

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