A co-modified polyurethane fireproof coating and its preparation method

Abstract

The present invention discloses a synergistically modified polyurethane fireproof coating and a preparation method thereof. The coating of the present invention can effectively exert the flame retardant synergistic effect of single-layer zirconium phosphate, ammonium polyphosphate and nano-aluminum oxide, integrating flame retardancy, smoke suppression and strengthening. The present invention uses polyethyleneimine macromolecules as an intercalating agent to achieve efficient exfoliation of zirconium phosphate, and at the same time grafts it on the single-layer zirconium phosphate lamella as a modifier to improve its compatibility with the organic matrix; polyethyleneimine and ammonium polyphosphate are used to carry out organic composite modification on single-layer zirconium phosphate to improve the dispersibility of single-layer zirconium phosphate, and synergistically exert the catalytic charring effect of ammonium polyphosphate and single-layer zirconium phosphate, significantly enhancing the flame retardant efficiency of zirconium phosphate; the organically composite modified single-layer zirconium phosphate and functionalized alumina are used together as a compound flame retardant. Through opposite charge attraction, these two kinds of nano-fillers are used as each other's spacer layers to effectively prevent the self-aggregation of each other and maximize the heat resistance and catalytic charring effects.

Description

Technical Field

[0001] The present invention belongs to the field of flame retardant coatings, and particularly relates to a polyurethane fireproof coating synergistically modified by organically compound-modified single-layer zirconium phosphate and functionalized alumina, and a preparation method thereof. Background Art

[0002] At present, polymer coatings are widely used, but most polymer materials are flammable, which severely limits the application of polymer coatings in fields with high flame retardant requirements. In order to reduce the fire risk and the release of toxic smoke, flame retardants are often added to polymer coatings.

[0003] In recent years, zirconium phosphate has attracted much attention in the field of flame retardant synergism due to its combined effects of catalytic carbonization, lamellar barrier action, and excellent heat resistance. However, when a single zirconium phosphate undergoes combustion, the carbon layer catalyzed and generated by it is relatively loose, has poor strength, and the carbonization effect time is short, and it cannot play a role in persistently protecting the carbon layer. In addition, zirconium phosphate has poor dispersibility and is prone to severe agglomeration and stacking in polymer materials, easily causing voids. To solve the above technical problems, in Patent CNI0820351A, zirconium phosphate is used as a synergistic agent and compounded with other flame retardants, but there are problems such as a large addition amount and still low flame retardant efficiency. In Patent CN109810545A, zirconium phosphate is exfoliated into single-layer nanosheets with high catalytic carbonization efficiency, thereby improving the flame retardant efficiency, but the compatibility problem between the nanosheets and the polymer matrix is not solved. In Patent CN109438759B, zirconium phosphate is modified by various organic substances to obtain nitrogen-phosphorus composite intercalated modified zirconium phosphate, which exerts the synergistic flame retardant effect of nitrogen-phosphorus-zirconium and simultaneously improves the flame retardant efficiency and dispersibility of zirconium phosphate, but zirconium phosphate is not effectively exfoliated.

[0004] In addition, when a coating containing nano-alumina suffers a fire, nano-alumina can absorb a large amount of heat energy and release carbon dioxide and water, thereby effectively preventing the spread of flames and the conduction of heat, reducing the harm of fire to buildings and personnel. Therefore, nano-alumina is also a widely used flame retardant. However, the compatibility between nano-alumina particles and the resin matrix interface is very poor, and the nano-particles are extremely easy to agglomerate and it is difficult to be evenly dispersed into the polymer matrix, which will severely reduce the flame retardant performance of the coating.

[0005] Therefore, it is particularly necessary to better improve the flame retardant efficiency of zirconium phosphate in polymer coatings, and at the same time significantly improve the dispersibility of zirconium phosphate and nano-alumina in the polymer matrix, so that the two can synergistically exert the flame retardant effect and effectively promote the application of zirconium phosphate and nano-alumina in the field of flame retardant synergism. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method of a polyurethane fireproof coating synergistically modified by an organic composite modified single-layer zirconium phosphate and functionalized alumina, and the polyurethane fireproof coating, preferably improving the flame retardancy efficiency of zirconium phosphate, and at the same time significantly improving the dispersibility of zirconium phosphate and nano-alumina in a polymer matrix, enabling the two to synergistically exert a flame retardant effect, and effectively promoting the application of zirconium phosphate and nano-alumina in the field of flame retardancy enhancement.

[0007] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0008] A synergistically modified polyurethane fireproof coating, which comprises a waterborne polyurethane and a compound flame retardant; wherein, the compound flame retardant is a dispersion liquid formed by dispersing an organic composite modified single-layer zirconium phosphate obtained by modifying zirconium phosphate with ammonium polyphosphate and polyethyleneimine and a functionalized alumina obtained by reacting nano-alumina with an amino silane coupling agent in deionized water.

[0009] Preferably, the polyurethane fireproof coating further comprises an antifoaming agent and a wetting agent. More preferably, the antifoaming agent is an organosilicon antifoaming agent, and the wetting agent is a waterborne organosilicon wetting agent.

[0010] Preferably, the components in the polyurethane fireproof coating are respectively by mass parts: 100 parts of the compound flame retardant dispersion liquid, 30 - 50 parts of waterborne polyurethane, 1 - 4 parts of antifoaming agent, and 1 - 3 parts of wetting agent.

[0011] The present invention also provides a preparation method of a polyurethane fireproof coating, which comprises the following steps:

[0012] S1. Preparation of the organic composite modified single-layer zirconium phosphate:

[0013] S11. Add zirconium phosphate into an aqueous solution of polyethyleneimine, place it in an ultrasonic crusher for ultrasonic peeling, filter by suction, wash with water until the filtrate is neutral, and dry to obtain polyethyleneimine modified single-layer zirconium phosphate;

[0014] S12. Add the above product into an aqueous solution of ammonium polyphosphate, and add a certain amount of NaCl, stir for a period of time, filter by suction, wash with water until the filtrate is neutral, and dry to obtain a single-layer zirconium phosphate organically compound modified by ammonium polyphosphate and polyethyleneimine;

[0015] S2. Preparation of the compound flame retardant:

[0016] S21. Disperse nano-alumina in a solvent, add an amino silane coupling agent, stir and react at a certain temperature and pH, filter by suction, wash, and dry to obtain functionalized alumina;

[0017] S22. Disperse the above-mentioned organically compound-modified single-layer zirconium phosphate and functionalized alumina in deionized water, and ultrasonically treat until evenly dispersed to obtain a compound flame retardant dispersion liquid;

[0018] S3. Preparation of polyurethane fireproof coating: Add waterborne polyurethane to the above-mentioned compound flame retardant dispersion liquid under rapid stirring, and then add an antifoaming agent and a wetting agent, and stir evenly to obtain a polyurethane fireproof coating synergistically modified by organically compound-modified single-layer zirconium phosphate and functionalized alumina.

[0019] Preferably, in step S11, the zirconium phosphate is α-zirconium phosphate, the mass ratio of zirconium phosphate to polyethyleneimine is 1:4 - 8, and the aqueous solution concentration of polyethyleneimine is 0.01 - 0.02 g / ml.

[0020] Preferably, in step S11, ultrasonically exfoliate for 10 - 20 h; in step S12, the stirring time is 5 - 8 h.

[0021] Preferably, in step S12, the aqueous solution concentration of ammonium polyphosphate is 0.01 - 0.02 g / ml, and the mass ratio of zirconium phosphate, ammonium polyphosphate, and NaCl is 1:1 - 5:0.05 - 0.1.

[0022] Preferably, in step S21, the mass ratio of nano-alumina to amino-silane coupling agent is 1:1 - 5, and the amino-silane coupling agent is one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane.

[0023] Preferably, in step S12, the solvent is a mixed solvent of water and ethanol with a volume ratio of 1:1, and the dosage ratio of nano-alumina to the solvent is 0.005 - 0.02 g / ml.

[0024] Preferably, in step S21, react at pH = 4 - 5 and 40 - 60 °C for 8 - 12 h, wherein the pH of the reaction solution is controlled by adding hydrochloric acid.

[0025] Preferably, in step S22, the mass ratio of organically compound-modified nano-zirconium phosphate to functionalized alumina is 1:0.5 - 2, and the solid content of the compound flame retardant dispersion liquid is 10 - 30%.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) In the present invention, polyethyleneimine macromolecules are used as intercalating agents. Under the synergistic action of the spatial effect of the intercalating agent macromolecules and ultrasonic waves, efficient exfoliation of zirconium phosphate is achieved. At the same time, the intercalating agent does not need to be removed and can be used as a modifier to graft onto the single-layer zirconium phosphate lamellae, endowing it with a large amount of reactive activity and positive charges on its surface, improving its compatibility with the organic matrix, and being conducive to the functional application of single-layer zirconium phosphate flakes;

[0028] (2) The present invention uses polyethyleneimine and ammonium polyphosphate to conduct organic composite modification on single-layer zirconium phosphate, which not only improves the dispersibility of single-layer zirconium phosphate, but also can synergistically exert the catalytic charring effects of ammonium polyphosphate and single-layer zirconium phosphate, significantly enhancing the flame retardancy efficiency of zirconium phosphate.

[0029] (3) The present invention uses positively charged functionalized alumina and negatively charged organically composite modified single-layer zirconium phosphate together as a compound flame retardant. Through the attraction of opposite charges, these two nano-fillers serve as spacer layers for each other, thus effectively preventing their own agglomeration, effectively solving the agglomeration problem of nano-particles in resin materials, and maximizing the heat resistance and catalytic charring effects.

[0030] (4) A compound flame retardant provided by the present invention can effectively exert the flame retardancy synergistic effect of single-layer zirconium phosphate, ammonium polyphosphate and nano-alumina, integrating flame retardancy, smoke suppression and strengthening.

[0031] The above description is only an overview of the technical solution of the present invention. In order to be able to more clearly understand the technical means of the present invention, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the present invention will be described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Brief Description of the Drawings

[0032] Figure 1 It is a process flow chart for the preparation method of the polyurethane fireproof coating of the present invention. Detailed Description of the Invention

[0033] Example 1

[0034] A polyurethane fireproof coating synergistically modified by organically composite modified single-layer zirconium phosphate and functionalized alumina. The preparation process of the polyurethane fireproof coating is as follows:

[0035] S1. Organically composite modified single-layer zirconium phosphate:

[0036] S11. Add 1 g of α-zirconium phosphate to 300 ml of an aqueous solution of polyethyleneimine (MW = 600) with a concentration of 0.02 g / ml, ultrasonically exfoliate in an ultrasonic crusher for 12 h, filter by suction, wash with water until neutral, and dry to obtain the product.

[0037] S12. Add 3 g of ammonium polyphosphate to 200 ml of deionized water, stir to dissolve, then add the above product, and add 0.06 g of NaCl. After stirring for 6 h, filter by suction, wash with water until the filtrate is neutral, and dry to obtain the organically composite modified single-layer zirconium phosphate.

[0038] S2. Preparation of the compound flame retardant

[0039] S21. Disperse 1 g of nano-aluminum oxide in a mixed solvent of 50 ml of water and 50 ml of ethanol, add 3 g of 3-aminopropyltrimethoxysilane, stir until homogeneous, add hydrochloric acid to adjust the pH value to 5, stir and react at 50 °C for 10 h, filter by suction, wash until the filtrate is neutral, and dry to obtain functionalized alumina.

[0040] S22. Disperse the above-mentioned organically compound-modified single-layer zirconium phosphate and functionalized alumina in deionized water according to a mass ratio of 1:1 to obtain a dispersion system with a solid content of 20%, and ultrasonically disperse until homogeneous to obtain a compound flame retardant dispersion liquid.

[0041] S3. Preparation of polyurethane fireproof coating

[0042] By mass, add 40 parts of waterborne polyurethane to 100 parts of the above-mentioned compound flame retardant dispersion liquid under rapid stirring, and then add 3 parts of defoaming agent (BYK024) and 2 parts of wetting agent (ZY-2648), stir evenly to obtain an organically modified nano-zirconium phosphate and alumina synergistically modified polyurethane fireproof coating.

[0043] Example 2

[0044] The difference between this example and Example 1 is that in step S12 of this example, 1 g of ammonium polyphosphate is added to 200 ml of deionized water.

[0045] Example 3

[0046] The difference between this example and Example 1 is that in step S12 of this example, 5 g of ammonium polyphosphate is added to 200 ml of deionized water.

[0047] Example 4

[0048] The difference between this example and Example 1 is that in step S22 of this example, the organically compound-modified single-layer zirconium phosphate and functionalized alumina are dispersed in deionized water according to a mass ratio of 1:0.5.

[0049] Example 5

[0050] The difference between this example and Example 1 is that in step S22 of this example, the organically compound-modified single-layer zirconium phosphate and functionalized alumina are dispersed in deionized water according to a mass ratio of 1:2.

[0051] Example 6

[0052] The difference between this example and Example 1 is that in step S22 of this example, a compound flame retardant dispersion liquid with a solid content of 10% is obtained.

[0053] Example 7

[0054] The difference between this embodiment and Embodiment 1 lies in that: in step S22 of this embodiment, a compound flame retardant dispersion with a solid content of 30% is obtained.

[0055] Comparative Example 1

[0056] The original α-zirconium phosphate was ultrasonically dispersed in deionized water to obtain a dispersion system with a solid content of 20%. Then, by mass, 40 parts of waterborne polyurethane were added to 100 parts of the α-zirconium phosphate dispersion system under rapid stirring, and then 3 parts of defoamer (BYK024) and 2 parts of wetting agent (ZY-2648) were added and stirred evenly to obtain a zirconium phosphate polyurethane fireproof coating.

[0057] Comparative Example 2

[0058] The original α-zirconium phosphate and the original nano-aluminum oxide were ultrasonically dispersed in deionized water at a mass ratio of 1:1 to obtain a dispersion system with a solid content of 20%. Then, by mass, 40 parts of waterborne polyurethane were added to 100 parts of the α-zirconium phosphate dispersion system under rapid stirring, and then 3 parts of defoamer (BYK024) and 2 parts of wetting agent (ZY-2648) were added and stirred evenly to obtain a zirconium phosphate / nano-aluminum oxide / polyurethane fireproof coating.

[0059] Comparative Example 3

[0060] The organically compound-modified single-layer zirconium phosphate prepared in Example 1 was ultrasonically dispersed in deionized water to obtain a dispersion system with a solid content of 20%. Then, by mass, 40 parts of waterborne polyurethane were added to 100 parts of the α-zirconium phosphate dispersion system under rapid stirring, and then 3 parts of defoamer (BYK024) and 2 parts of wetting agent (ZY-2648) were added and stirred evenly to obtain an organically compound-modified zirconium phosphate / polyurethane fireproof coating.

[0061] Comparative Example 4

[0062] The organically compound-modified single-layer zirconium phosphate prepared in Example 1 and the original nano-aluminum oxide were ultrasonically dispersed in deionized water at a mass ratio of 1:1 to obtain a dispersion system with a solid content of 20%. Then, by mass, 40 parts of waterborne polyurethane were added to 100 parts of the α-zirconium phosphate dispersion system under rapid stirring, and then 3 parts of defoamer (BYK024) and 2 parts of wetting agent (ZY-2648) were added and stirred evenly to obtain a zirconium phosphate / nano-aluminum oxide / polyurethane fireproof coating.

[0063] The coatings obtained in Examples 1-7 and Comparative Examples 1-4 were evenly brushed on the surface of a steel sheet (sandblasted to Sa2 level), the average thickness of the coating was kept at about 1.5 mm, and it was cured at room temperature for one week to obtain a specimen coating. The morphology and limiting fire resistance time of each coating preparation process are listed in Table 1.

[0064] Table 1 Morphology and Limiting Fire Resistance Time of the Preparation Process of Polyurethane Fire Retardant Coatings Obtained in Examples 1-7 and Comparative Examples 1-4

[0065] Method Morphology during the coating preparation process Ultimate refractory time Example 1 Smooth, delicate, no particle adhesion 71min Example 2 Smooth, delicate, no particle adhesion 63min Example 3 Smooth, delicate, no particle adhesion 77min Example 4 Smooth, delicate, no particle adhesion 80min Example 5 Smooth, delicate, no particle adhesion 64min Example 6 Smooth, delicate, no particle adhesion 60min Example 7 Smooth, delicate, no particle adhesion 84min Comparative Example 1 There is a small amount of particle adhesion 38min Comparative Example 2 There is a small amount of particle adhesion 40min Comparative Example 3 Smooth, delicate, no particle adhesion 52min Comparative Example 4 There is a small amount of particle adhesion 46min

[0066] As can be seen from Examples 1-7 in combination with Table 1, the compound flame retardant system prepared by the present invention can not only effectively exert the flame retardant synergistic effect of single-layer zirconium phosphate-ammonium polyphosphate-nanoaluminum oxide, but also utilize the attraction between positive and negative charges, so that the two kinds of nanoparticles used in combination serve as each other's spacer layers, thus effectively preventing the self-aggregation of each other. In addition, there are a large number of functional groups in the flame retardant system, thus effectively improving the interfacial compatibility between the flame retardant particles and the resin matrix. Therefore, the prepared coating has very excellent fire protection performance. When α-zirconium phosphate is used alone as a flame retardant, due to its poor catalytic charring effect and poor dispersibility in the resin matrix, the flame retardant performance of the coating cannot be effectively improved, and the results are shown in Comparative Example 1. In Comparative Example 2, the original α-zirconium phosphate and the original nanoaluminum oxide are used synergistically as flame retardants, but due to the poor interaction between them, serious aggregation will occur in the resin matrix. Therefore, the synergistic flame retardant effect of the two cannot be fully utilized, so the flame retardant performance of the coating is only effectively improved. In Comparative Example 3, the organically compound-modified single-layer zirconium phosphate is used as a flame retardant. The polyphosphoric acid generated by the thermal decomposition of ammonium polyphosphate in the compound modifier also has a catalytic carbonization effect on the resin matrix and can play a flame retardant effect synergistically with the single-layer zirconium phosphate. Another modifier, polyethyleneimine, provides a large number of amino groups and can form a good interfacial bond with the resin matrix. Therefore, the flame retardant performance of the coating in Comparative Example 3 is significantly improved. In Comparative Example 4, the organically compound-modified single-layer zirconium phosphate and the original nanoaluminum oxide are used synergistically as flame retardants, but due to the poor dispersibility and serious aggregation of the original nanoaluminum oxide, the synergistic flame retardant effect still cannot be fully exerted. Therefore, compared with the results of Comparative Example 3, the flame retardant performance of the coating in Comparative Example 4 decreases.

[0067] The present invention is not limited to the above specific embodiments. For those of ordinary skill in the art, various changes made without creative labor starting from the above concepts fall within the protection scope of the present invention.

Claims

1. A synergistically modified polyurethane fire retardant coating, characterized in that: The polyurethane fire retardant coating comprises waterborne polyurethane and a compound flame retardant; the compound flame retardant is a dispersion formed by dispersing an organic composite modified single-layer zirconium phosphate obtained by modifying zirconium phosphate through ammonium polyphosphate and polyethyleneimine and a functional alumina obtained by reacting nano alumina with an aminosilane coupling agent in deionized water.

2. The polyurethane fire retardant coating according to claim 1, characterized in that: The polyurethane fire retardant coating also includes a defoamer and a wetting agent.

3. The polyurethane fire retardant coating according to claim 2, characterized in that: The components in the polyurethane fire retardant coating are respectively: 100 parts of compound flame retardant dispersion, 30-50 parts of waterborne polyurethane, 1-4 parts of defoaming agent, and 1-3 parts of wetting agent in terms of mass fraction.

4. The polyurethane fire retardant coating according to claim 2, characterized in that: The defoamer is an organosilicon defoamer, and the wetting agent is an aqueous organosilicon wetting agent.

5. A method for preparing the polyurethane fire retardant coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Preparation of organic composite modified monolayer zirconium phosphate: S11. The zirconium phosphate was added to an aqueous solution of polyethyleneimine, placed in an ultrasonic crusher, subjected to ultrasonic stripping, filtered, washed with water until the filtrate was neutral, and dried to obtain a polyethyleneimine-modified monolayer zirconium phosphate; S12. The above product was added to an aqueous solution of ammonium polyphosphate, and a certain amount of NaCl was added. After stirring for a period of time, the mixture was filtered and washed with water until the filtrate was neutral, and dried to obtain a monolayer zirconium phosphate modified with ammonium polyphosphate and polyethyleneimine organic composite; S2. Preparation of compound flame retardant: S21. The nano-alumina is dispersed in a solvent, an aminosilane coupling agent is added, the reaction is stirred at a certain temperature and pH, the reaction is filtered, washed, and dried to obtain functionalized alumina; S22. The organic composite modified monolayer zirconium phosphate and functionalized alumina are dispersed in deionized water and ultrasonically dispersed to obtain a composite flame retardant dispersion; S3. Preparation of polyurethane fire retardant coating: Add water-based polyurethane to the above-mentioned compound flame retardant dispersion under rapid stirring, then add defoamer and wetting agent, stir evenly to obtain polyurethane fire retardant coating synergistically modified by organic composite modified single-layer zirconium phosphate and functionalized alumina.

6. The preparation method according to claim 5, characterized in that: In the step S11, the zirconium phosphate is α-zirconium phosphate, the mass ratio of zirconium phosphate to polyethyleneimine is 1:4-8, and the concentration of the polyethyleneimine aqueous solution is 0.01-0.02 g / ml.

7. The preparation method according to claim 5, characterized in that: In the step S12, the concentration of the ammonium polyphosphate aqueous solution is 0.01-0.02 g / ml, and the mass ratio of zirconium phosphate, ammonium polyphosphate and NaCl is 1:1-5:0.05-0.

1.

8. The preparation method according to claim 5, characterized in that: In the step S21, the mass ratio of nano-alumina to aminosilane coupling agent is 1:1-5, and the aminosilane coupling agent is one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-aminopropylmethyldiethoxysilane.

9. The preparation method according to claim 5, characterized in that: In the step S12, the solvent is a mixed solvent of water and ethanol in a volume ratio of 1:1, and the dosage ratio of the nano-alumina to the solvent is 0.005-0.02 g / ml.

10. The preparation method according to claim 5, characterized in that: In the step S22, the mass ratio of the organic composite modified nano zirconium phosphate to the functionalized alumina is 1:0.5-2, and the solid content of the composite flame retardant dispersion is 10-30%.

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