A kind of organosilicon modified waterborne polyurethane coating and its preparation method and application

Abstract

The present invention discloses an organosilicon-modified waterborne polyurethane coating, a preparation method and an application thereof. The composition of the organosilicon-modified waterborne polyurethane coating of the present invention includes waterborne polyurethane emulsion, epoxy resin, hydroxyl-terminated hyperbranched organosilicon polymer, anti-rust pigment, dispersant, defoamer, leveling agent, cellulose thickener, diisocyanate-modified graphene oxide and isocyanate curing agent. The organosilicon-modified waterborne polyurethane coating of the present invention has simple composition, safety and environmental protection, and convenient construction. After film formation, the paint film has the advantages of good water resistance, good acid / alkali resistance, good wear resistance, good weather resistance, high mechanical strength, strong adhesion, etc., and is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The invention relates to the technical field of waterborne polyurethane coatings, and in particular to an organosilicon-modified waterborne polyurethane coating and a preparation method and application thereof. Background Art

[0002] Aqueous polyurethane is a polyurethane system that uses water instead of organic solvent as a dispersion medium, also known as water-dispersed polyurethane, water-based polyurethane or water-based polyurethane. Aqueous polyurethane uses water as a solvent, is safe and environmentally friendly, and the paint film has excellent wear resistance, acid / alkali resistance and weather resistance after film formation, and the performances such as the hardness and softness of the paint film are highly controllable, and has been widely used in the fields of buildings, furniture, vehicles, ships, etc. However, the existing aqueous polyurethane coatings generally have problems such as poor water resistance (caused by hydrophilic groups) of the paint film after film formation, low mechanical strength (low cross-linking density of the paint film), etc., which are difficult to fully meet the requirements of practical applications, and practical applications are greatly restricted. At present, mainly by directly adding hydrophobic components in aqueous polyurethane coatings to improve the water resistance of paint film, this method can improve the water resistance of paint film to a certain extent, but due to the poor compatibility of hydrophobic components with aqueous polyurethane systems, other properties of the paint film will be significantly adversely affected.

[0003] Therefore, it is of great significance to develop a waterborne polyurethane coating with good water resistance and high mechanical strength after film formation.

[0004] The above statements merely provide background information related to the present invention and do not necessarily constitute prior art. Summary of the invention

[0005] The purpose of the present invention is to provide an organosilicon-modified waterborne polyurethane coating and a preparation method and application thereof.

[0006] The technical solution adopted by the present invention is:

[0007] A silicone-modified waterborne polyurethane coating comprising the following components in parts by weight:

[0008] Component A:

[0009] Water-based polyurethane emulsion: 100 parts;

[0010] Epoxy resin: 20 to 40 parts;

[0011] Hydroxyl terminated hyperbranched organosilicon polymer: 10 to 20 parts;

[0012] Anti-rust pigment: 10 to 25 parts;

[0013] Dispersant: 1 to 5 parts;

[0014] Defoaming agent: 2 to 7 parts;

[0015] Leveling agent: 3 to 10 parts;

[0016] Cellulose thickener: 2.5 to 7.5 parts;

[0017] Component B:

[0018] Diisocyanate-modified graphene oxide: 3 to 10 parts;

[0019] Isocyanate curing agent: 8 to 25 parts.

[0020] Preferably, the aqueous polyurethane emulsion is a hydroxy polyurethane dispersion of Wanhua Chemical 4166, Covestro's hydroxy polyurethane dispersion U XP2750, hydroxyl polyurethane dispersion from Covestro At least one of U2757.

[0021] Preferably, the epoxy resin is bisphenol A epoxy resin.

[0022] More preferably, the epoxy resin is at least one of epoxy resin E-44 and epoxy resin E-51.

[0023] Preferably, the hydroxyl-terminated hyperbranched organosilicon polymer is prepared by a preparation method comprising the following steps: mixing an organosilane compound, polyhydroxyamine and phosphotungstic acid, heating to 120°C to 160°C for reaction for 3h to 8h, and then removing volatile components by reduced pressure distillation to obtain a hydroxyl-terminated hyperbranched organosilicon polymer.

[0024] Preferably, the molar ratio of the organic silane compound to the polyhydroxyamine is 1:2.5-4.

[0025] Preferably, the organic silane compound is at least one of methyltriethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane and benzyltriethoxysilane.

[0026] Preferably, the polyhydroxyamine is at least one of diethanolamine, triethanolamine and triisopropanolamine.

[0027] Preferably, the weight of the phosphotungstic acid is 0.3% to 1.2% of the weight of the organosilane compound.

[0028] Preferably, the anti-rust pigment is at least one of zinc phosphate, aluminum tripolyphosphate, and zinc aluminum phosphate.

[0029] Preferably, the dispersant is at least one of polycarboxylate and ammonium polyacrylate.

[0030] More preferably, the dispersant is at least one of BYK-190, BYK-191, and TEGO-760W.

[0031] Preferably, the defoamer is a silicone defoamer.

[0032] More preferably, the defoamer is at least one of BYK-022, BYK-024, TEGO Airex 902W and TEGO Foamex 822.

[0033] Preferably, the leveling agent is a polyether-modified polysiloxane leveling agent.

[0034] Further preferably, the leveling agent is at least one of the leveling agent RM-2020NPR of Dow Chemical, the leveling agent BYK-333 of BYK Chemical, and the leveling agent TEGO-410 of Digo.

[0035] Preferably, the cellulose thickener is at least one of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose and ethyl hydroxyethyl cellulose.

[0036] Preferably, the diisocyanate-modified graphene oxide is prepared by a preparation method comprising the following steps: ultrasonically dispersing graphene oxide and diisocyanate in an organic solvent, adding a catalyst, reacting for 8h to 15h in a protective atmosphere at a temperature of 65°C to 80°C, centrifuging, washing the solid with water and drying to obtain diisocyanate-modified graphene oxide.

[0037] Preferably, the weight ratio of the graphene oxide to diisocyanate is 1:15-30.

[0038] Preferably, the diisocyanate is at least one of toluene diisocyanate, 4,4'-methylenebis(phenyl isocyanate), isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate.

[0039] Preferably, the weight ratio of the diisocyanate to the organic solvent is 1:2-6.

[0040] Preferably, the organic solvent is at least one of N,N-dimethylformamide, acetone and toluene.

[0041] Preferably, the weight of the catalyst is 0.1% to 0.5% of the weight of the diisocyanate.

[0042] Preferably, the catalyst is an organotin catalyst.

[0043] More preferably, the catalyst is at least one of stannous octoate, dibutyltin dilaurate, and dibutyltin diacetate.

[0044] Preferably, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0045] Preferably, the isocyanate curing agent is at least one of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate and dicyclohexylmethane diisocyanate.

[0046] A method for preparing the above-mentioned organosilicon-modified waterborne polyurethane coating comprises the following steps:

[0047] 1) mixing an aqueous polyurethane emulsion, an epoxy resin, a hydroxyl-terminated hyperbranched organosilicon polymer, an anti-rust pigment, a dispersant, a defoamer, a leveling agent and a cellulose thickener and then packaging them as component A, and mixing a diisocyanate-modified graphene oxide and an isocyanate curing agent and then packaging them as component B;

[0048] 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

[0049] An application of the above-mentioned organosilicon-modified waterborne polyurethane coating in metal corrosion protection.

[0050] The beneficial effects of the present invention are as follows: the organic silicon modified waterborne polyurethane coating of the present invention has a simple composition, is safe and environmentally friendly, and is easy to construct; after film formation, the paint film has the advantages of good water resistance, good acid / alkali resistance, good wear resistance, good weather resistance, high mechanical strength, high adhesion, etc., and is suitable for large-scale industrial production and application.

[0051] Specifically:

[0052] 1) The organosilicon-modified waterborne polyurethane coating of the present invention is added with waterborne polyurethane emulsion, epoxy resin (the formed paint film has high strength and rigidity and can withstand greater pressure and impact) and hydroxyl-terminated hyperbranched organosilicon polymer (having a hyperbranched structure, which can increase the crosslinking density of the paint film; having an organosilicon hydrophobic segment, which can make the paint film hydrophobic, thereby improving the water resistance of the paint film). There is a synergistic effect between the three, which can significantly increase the crosslinking density and density of the paint film, thereby greatly improving the water resistance, acid / alkali resistance, wear resistance, weather resistance and mechanical strength of the paint film;

[0053] 2) The organosilicon-modified waterborne polyurethane coating of the present invention is added with diisocyanate-modified graphene oxide (graphene oxide is a reinforcing filler), which can be grafted into the polymer network structure through a cross-linking reaction. Compared with directly adding graphene oxide to the waterborne polyurethane coating, the dispersion uniformity of graphene oxide in the paint film is significantly improved, and ultimately the mechanical strength of the paint film can be effectively improved without affecting other properties of the paint film;

[0054] 3) The organosilicon-modified waterborne polyurethane coating of the present invention contains a cellulose thickener, and the hydroxyl / carboxyl groups contained in the cellulose thickener can form hydrogen bonds with the hydroxyl / carboxyl groups contained in the edge of the graphene oxide sheet structure in the diisocyanate-modified graphene oxide, so that the cellulose thickener can be uniformly embedded in the polymer network structure, which can effectively improve the flexibility and impact resistance of the paint film, making the paint film more resistant to external force deformation, and effectively solving the problem that the existing waterborne polyurethane coating is prone to cracks during the film forming process;

[0055] 4) The organosilicon-modified waterborne polyurethane coating of the present invention has simple composition, is safe and environmentally friendly, and is easy to construct. It can be used in the field of metal corrosion protection and is suitable for large-scale industrial production and application. DETAILED DESCRIPTION

[0056] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0057] Embodiment 1:

[0058] A silicone-modified waterborne polyurethane coating, the composition of which is shown in the following table:

[0059] Table 1 Composition of a silicone modified waterborne polyurethane coating

[0060]

[0061]

[0062] Note:

[0063] The preparation method of the hydroxyl terminated hyperbranched organosilicon polymer is as follows:

[0064] Methyltriethoxysilane, diethanolamine and phosphotungstic acid are mixed, the molar ratio of methyltriethoxysilane to diethanolamine is 1:4, the weight of phosphotungstic acid is 0.6% of the weight of methyltriethoxysilane, the temperature is then raised to 130° C. for reaction for 6 hours, and the volatile components are removed by reduced pressure distillation to obtain a hydroxyl-terminated hyperbranched organosilicon polymer.

[0065] The preparation method of diisocyanate-modified graphene oxide is as follows:

[0066] Graphene oxide and toluene diisocyanate are ultrasonically dispersed in acetone, the weight ratio of graphene oxide, toluene diisocyanate and acetone is 1:25:80, and then stannous octoate is added, the weight of stannous octoate is 0.3% of the weight of toluene diisocyanate, and then placed in a nitrogen atmosphere at a temperature of 65°C for 15 hours, centrifuged, and the solid is washed with water and dried to obtain diisocyanate-modified graphene oxide.

[0067] The preparation method of the above-mentioned organosilicon-modified waterborne polyurethane coating is as follows:

[0068] 1) Disperse hydroxy polyurethane 4166, epoxy resin E-44, hydroxyl-terminated hyperbranched silicone polymer, zinc phosphate, dispersant BYK-190, defoamer BYK-024, leveling agent RM-2020NPR and hydroxypropyl methylcellulose are mixed evenly and then packaged as component A, and diisocyanate-modified graphene oxide and toluene diisocyanate are mixed evenly and then packaged as component B;

[0069] 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

[0070] Embodiment 2:

[0071] A silicone-modified waterborne polyurethane coating, the composition of which is shown in the following table:

[0072] Table 2 Composition of a silicone modified waterborne polyurethane coating

[0073]

[0074]

[0075] Note:

[0076] The preparation method of diisocyanate-modified graphene oxide is as follows:

[0077] Graphene oxide and hexamethylene diisocyanate are ultrasonically dispersed in acetone, the weight ratio of graphene oxide, hexamethylene diisocyanate and acetone is 1:25:80, and then stannous octoate is added, the weight of stannous octoate is 0.2% of the weight of hexamethylene diisocyanate, and then placed in a nitrogen atmosphere at a temperature of 70°C for reaction for 12 hours, centrifuged, and the solid is washed with water and dried to obtain diisocyanate-modified graphene oxide.

[0078] The preparation method of the above-mentioned organosilicon-modified waterborne polyurethane coating is as follows:

[0079] 1) Disperse hydroxy polyurethane 4166, epoxy resin E-44, hydroxyl-terminated hyperbranched silicone polymer, zinc phosphate, dispersant BYK-191, defoamer BYK-024, leveling agent RM-2020NPR and hydroxypropyl methylcellulose are mixed evenly and then packaged as component A, and diisocyanate-modified graphene oxide and toluene diisocyanate are mixed evenly and then packaged as component B;

[0080] 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

[0081] Embodiment 3:

[0082] A silicone-modified waterborne polyurethane coating, the composition of which is shown in the following table:

[0083] Table 3 Composition of a silicone modified waterborne polyurethane coating

[0084]

[0085]

[0086] Note:

[0087] The preparation method of the hydroxyl terminated hyperbranched organosilicon polymer is as follows:

[0088] Phenyltriethoxysilane, diethanolamine and phosphotungstic acid are mixed, the molar ratio of phenyltriethoxysilane to diethanolamine is 1:3.5, the weight of phosphotungstic acid is 0.4% of the weight of phenyltriethoxysilane, and then the temperature is raised to 150° C. for reaction for 5 hours, and then the volatile components are removed by reduced pressure distillation to obtain a hydroxyl-terminated hyperbranched silicone polymer.

[0089] The preparation method of the above-mentioned organosilicon-modified waterborne polyurethane coating is as follows:

[0090] 1) Disperse hydroxy polyurethane U XP2750, epoxy resin E-51, hydroxyl-terminated hyperbranched silicone polymer, zinc phosphate, dispersant BYK-190, defoamer TEGO Airex 902W, leveling agent BYK-333 and hydroxyethyl cellulose are mixed evenly and then divided into component A, and diisocyanate-modified graphene oxide and isophorone diisocyanate are mixed evenly and then divided into component B;

[0091] 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

[0092] Embodiment 4:

[0093] A silicone-modified waterborne polyurethane coating, the composition of which is shown in the following table:

[0094] Table 4 Composition of a silicone modified waterborne polyurethane coating

[0095]

[0096]

[0097] Note:

[0098] The preparation method of the hydroxyl terminated hyperbranched organosilicon polymer is as follows:

[0099] Methyltriethoxysilane, triisopropanolamine and phosphotungstic acid are mixed, the molar ratio of methyltriethoxysilane to triisopropanolamine is 1:2.5, the weight of phosphotungstic acid is 0.5% of the weight of methyltriethoxysilane, the temperature is then raised to 140°C for reaction for 8 hours, and the volatile components are removed by reduced pressure distillation to obtain a hydroxyl-terminated hyperbranched organosilicon polymer.

[0100] The preparation method of diisocyanate-modified graphene oxide is as follows:

[0101] Graphene oxide and isophorone diisocyanate are ultrasonically dispersed in toluene, the weight ratio of graphene oxide, isophorone diisocyanate and toluene is 1:15:50, and then dibutyltin dilaurate is added, the weight of dibutyltin dilaurate is 0.5% of the weight of isophorone diisocyanate, and then placed in a nitrogen atmosphere at a temperature of 70°C for reaction for 10 hours, centrifuged, and the solid is washed with water and dried to obtain diisocyanate-modified graphene oxide.

[0102] The preparation method of the above-mentioned organosilicon-modified waterborne polyurethane coating is as follows:

[0103] 1) Disperse hydroxy polyurethane U 2757, epoxy resin E-44, hydroxyl-terminated hyperbranched silicone polymer, aluminum tripolyphosphate, dispersant TEGO-760W, defoamer TEGO Foamex 822, leveling agent RM-2020NPR and carboxymethyl cellulose are mixed evenly and then packaged as component A, and diisocyanate-modified graphene oxide and diphenylmethane diisocyanate are mixed evenly and then packaged as component B;

[0104] 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

[0105] Embodiment 5:

[0106] A silicone-modified waterborne polyurethane coating, the composition of which is shown in the following table:

[0107] Table 5 Composition of a silicone modified waterborne polyurethane coating

[0108]

[0109]

[0110] Note:

[0111] The preparation method of the hydroxyl terminated hyperbranched organosilicon polymer is as follows:

[0112] Methyltriethoxysilane, triethanolamine and phosphotungstic acid are mixed, the molar ratio of methyltriethoxysilane to triethanolamine is 1:3, the weight of phosphotungstic acid is 0.6% of the weight of methyltriethoxysilane, the temperature is then raised to 140°C for reaction for 5 hours, and the volatile components are removed by reduced pressure distillation to obtain a hydroxyl-terminated hyperbranched organosilicon polymer.

[0113] The preparation method of diisocyanate-modified graphene oxide is as follows:

[0114] Graphene oxide and toluene diisocyanate are ultrasonically dispersed in N,N-dimethylformamide, the weight ratio of graphene oxide, toluene diisocyanate and N,N-dimethylformamide is 1:20:80, and then dibutyltin dilaurate is added, the weight of dibutyltin dilaurate is 0.3% of the weight of toluene diisocyanate, and then placed in a nitrogen atmosphere at a temperature of 70°C for reaction for 10 hours, centrifuged, and the solid is washed with water and dried to obtain diisocyanate-modified graphene oxide.

[0115] The preparation method of the above-mentioned organosilicon-modified waterborne polyurethane coating is as follows:

[0116] 1) Disperse hydroxy polyurethane 4166, epoxy resin E-44, hydroxyl-terminated hyperbranched silicone polymer, aluminum tripolyphosphate, dispersant BYK-190, defoamer BYK-024, leveling agent RM-2020NPR and hydroxyethyl cellulose are mixed evenly and then packaged as component A, and diisocyanate-modified graphene oxide and toluene diisocyanate are mixed evenly and then packaged as component B;

[0117] 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

[0118] Comparative Example 1:

[0119] A waterborne polyurethane coating, except that the epoxy resin E-44 is replaced by an equal weight portion of hydroxyl polyurethane dispersion Except for 4166, the rest is exactly the same as the organosilicon-modified waterborne polyurethane coating of Example 5.

[0120] Comparative Example 2:

[0121] A waterborne polyurethane coating, except that the hydroxyl-terminated hyperbranched silicone polymer is replaced by an equal weight portion of a hydroxyl polyurethane dispersion Except for 4166, the rest is exactly the same as the organosilicon-modified waterborne polyurethane coating of Example 5.

[0122] Comparative Example 3:

[0123] A waterborne polyurethane coating, except that the epoxy resin E-44, the hydroxyl-terminated hyperbranched silicone polymer and the hydroxyethyl cellulose are replaced by equal parts by weight of a hydroxyl polyurethane dispersion Except for 4166, the rest is exactly the same as the organosilicon-modified waterborne polyurethane coating of Example 5.

[0124] Comparative Example 4:

[0125] A waterborne polyurethane coating, except that the hydroxyethyl cellulose is replaced by an equal weight portion of hydroxy polyurethane dispersion Except for 4166, the rest is exactly the same as the organosilicon-modified waterborne polyurethane coating of Example 5.

[0126] Comparative Example 5:

[0127] A waterborne polyurethane coating is identical to the silicone-modified waterborne polyurethane coating of Example 5 except that the diisocyanate-modified graphene oxide is replaced by an equal weight portion of toluene diisocyanate.

[0128] Performance Testing:

[0129] The silicone-modified waterborne polyurethane coatings of Examples 1 to 5 and the waterborne polyurethane coatings of Comparative Examples 1 to 5 were sprayed on the surface of steel plates (sandpaper polished, cleaned and dried in advance), and then cured at room temperature (25° C.) to form films. The properties of the paint films were then tested. The test results are shown in the following table:

[0130] Table 6 Performance test results of silicone modified waterborne polyurethane coatings of Examples 1 to 5

[0131]

[0132] Table 7 Performance test results of waterborne polyurethane coatings of Comparative Examples 1 to 5

[0133]

[0134] Note:

[0135] Adhesion: Tested in accordance with "GB / T 9286-2021 Cross-cut test for paint and varnish films";

[0136] Pencil hardness: Test according to "GB / T 6739-2022 Paints and varnishes - Pencil method for determination of film hardness";

[0137] Impact strength: Tested with reference to "GB / T 1732-1993 Determination of impact resistance of paint film";

[0138] Water resistance: Refer to "GB / T 1733-1993 Determination of water resistance of paint film" and use the immersion method to test. The specific process is: immerse the paint film sample in water for 168 hours, and then observe whether the paint film loses color, bubbles, wrinkles, falls off and peels off. If there is no such situation, it passes;

[0139] Acid resistance: Tested in accordance with Method A of "GB / T 9274-1988 Determination of resistance of paints and varnishes to liquid media";

[0140] Alkali resistance: Tested in accordance with Method A of "GB / T 9274-1988 Determination of resistance of paints and varnishes to liquid media";

[0141] Neutral salt spray resistance: Tested in accordance with "GB / T 1771-2007 Determination of neutral salt spray resistance of paints and varnishes";

[0142] Anti-ultraviolet aging: Tested with reference to "GB / T 1865-2009 Paints and varnishes - Artificial weathering and artificial radiation exposure - filtered xenon arc radiation".

[0143] From Table 6 and Table 7, we can see that:

[0144] 1) The paint films formed by the silicone-modified waterborne polyurethane coatings of Examples 1 to 5 have high adhesion, high water contact angle (in a hydrophobic state), high hardness, high impact strength, good water resistance, good acid resistance, good alkali resistance, good neutral salt spray resistance, and good resistance to ultraviolet light aging, indicating that the present invention significantly improves the water resistance, acid / alkali resistance, wear resistance, weather resistance, mechanical strength and other properties of the paint film by adding epoxy resin, hydroxyl-terminated hyperbranched silicone polymer, diisocyanate-modified graphene oxide and cellulose thickener to the waterborne polyurethane coating;

[0145] 2) The waterborne polyurethane coating of Comparative Example 1 (without epoxy resin E-44) has a lower hardness than the silicone-modified waterborne polyurethane coating of Example 5, and the paint film has worse impact resistance, acid resistance, alkali resistance, neutral salt spray resistance and UV aging resistance, indicating that the addition of epoxy resin can increase the crosslinking density of the paint film, thereby improving the impact resistance, acid resistance, alkali resistance and other properties of the paint film;

[0146] 3) The waterborne polyurethane coating of Comparative Example 2 (without the addition of hydroxyl-terminated hyperbranched organosilicon polymer) has a lower adhesion, a smaller water contact angle, and a smaller hardness than the organosilicon-modified waterborne polyurethane coating of Example 5, and the water resistance, acid resistance, neutral salt spray resistance, and UV aging resistance of the paint film are all worse, indicating that the addition of hydroxyl-terminated hyperbranched organosilicon polymer can increase the crosslinking density of the paint film and give the paint film hydrophobic properties, thereby improving the adhesion, water contact angle, water resistance, acid resistance, and other properties of the paint film;

[0147] 4) The waterborne polyurethane coating of Comparative Example 3 (without epoxy resin E-44, hydroxyl-terminated hyperbranched organosilicon polymer and hydroxyethyl cellulose) has worse properties in all aspects of the formed paint film than the organosilicon-modified waterborne polyurethane coating of Example 5, indicating that epoxy resin, hydroxyl-terminated hyperbranched organosilicon polymer and hydroxyethyl cellulose are all crucial and indispensable;

[0148] 5) The waterborne polyurethane coating of Comparative Example 4 (without hydroxyethyl cellulose) has a smaller hardness and a lower impact resistance than the silicone-modified waterborne polyurethane coating of Example 5, indicating that the addition of hydroxyethyl cellulose can improve the flexibility and impact resistance of the coating;

[0149] 6) The waterborne polyurethane coating of Comparative Example 5 (without addition of diisocyanate-modified graphene oxide) has a smaller hardness and a lower impact strength than the silicone-modified waterborne polyurethane coating of Example 5, indicating that the addition of diisocyanate-modified graphene oxide can improve the mechanical strength of the paint film;

[0150] In summary, the present invention can significantly improve the water resistance, acid / alkali resistance, wear resistance, weather resistance, mechanical strength and other properties of the paint film by adding epoxy resin, hydroxyl-terminated hyperbranched silicone polymer, cellulose thickener and diisocyanate-modified graphene oxide to the water-based polyurethane coating. The obtained water-based polyurethane coating fully meets the practical application requirements in the field of metal corrosion protection and is suitable for large-scale industrial production and application.

[0151] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A silicone-modified waterborne polyurethane coating, characterized in that: The composition comprises the following components in parts by weight: Component A: Water-based polyurethane emulsion: 100 parts; Epoxy resin: 20 to 40 parts; Hydroxyl terminated hyperbranched organosilicon polymer: 10 to 20 parts; Anti-rust pigment: 10 to 25 parts; Dispersant: 1 to 5 parts; Defoaming agent: 2 to 7 parts; Leveling agent: 3 to 10 parts; Cellulose thickener: 2.5 to 7.5 parts; Component B: Diisocyanate-modified graphene oxide: 3 to 10 parts; Isocyanate curing agent: 8 to 25 parts; The aqueous polyurethane emulsion is at least one of the hydroxyl polyurethane dispersion Lacper® 4166 of Wanhua Chemical, the hydroxyl polyurethane dispersion Bayhydrol® U XP2750 of Covestro, and the hydroxyl polyurethane dispersion Bayhydrol® U 2757 of Covestro; The epoxy resin is bisphenol A epoxy resin; The hydroxyl-terminated hyperbranched organosilicon polymer is prepared by a preparation method comprising the following steps: mixing an organosilane compound, a polyhydroxyamine and phosphotungstic acid, heating the mixture to 120° C. to 160° C. for reaction for 3 h to 8 h, and then removing volatile components by reduced pressure distillation to obtain a hydroxyl-terminated hyperbranched organosilicon polymer; The molar ratio of the organosilane compound to the polyhydroxyamine is 1:2.5-4; The organosilane compound is at least one of methyltriethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane and benzyltriethoxysilane; The polyhydroxyamine is at least one of diethanolamine, triethanolamine and triisopropanolamine; The cellulose thickener is at least one of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose and ethyl hydroxyethyl cellulose; The diisocyanate-modified graphene oxide is prepared by a preparation method comprising the following steps: ultrasonically dispersing graphene oxide and diisocyanate in an organic solvent, adding a catalyst, reacting for 8h to 15h under a protective atmosphere and a temperature of 65° C. to 80° C., centrifuging, washing and drying the solid, and obtaining the diisocyanate-modified graphene oxide.

2. The organosilicon-modified waterborne polyurethane coating according to claim 1, characterized in that: The anti-rust pigment is at least one of zinc phosphate, aluminum tripolyphosphate, and zinc aluminum phosphate.

3. The organosilicon-modified waterborne polyurethane coating according to claim 1, characterized in that: The dispersant is at least one of polycarboxylate and polyacrylic acid ammonium salt; the defoamer is an organosilicon defoamer; and the leveling agent is a polyether-modified polysiloxane leveling agent.

4. The organosilicon-modified waterborne polyurethane coating according to claim 1, characterized in that: The isocyanate curing agent is at least one of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate and dicyclohexylmethane diisocyanate.

5. A method for preparing a silicone-modified waterborne polyurethane coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Mixing waterborne polyurethane emulsion, epoxy resin, hydroxyl-terminated hyperbranched silicone polymer, anti-rust pigment, dispersant, defoamer, leveling agent and cellulose thickener and packaging them as component A, and mixing diisocyanate-modified graphene oxide and isocyanate curing agent and packaging them as component B; 2) Mix component A and component B to obtain a silicone-modified waterborne polyurethane coating.

6. Use of the organosilicon-modified waterborne polyurethane coating as claimed in any one of claims 1 to 4 in metal corrosion protection.

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