A kind of anti-aging modified waterborne polyurethane and its preparation method and application

Abstract

The present invention belongs to the field of waterborne polyurethane materials, and specifically discloses a kind of aging-resistant modified waterborne polyurethane and its preparation method and application. The raw materials for preparing the aging-resistant modified waterborne polyurethane of the present invention include the following components in parts by weight: 30-70 parts of carbon dioxide copolymer polyol, 30-70 parts of polybutadiene polyol, 30-70 parts of aliphatic diisocyanate, 1-10 parts of cross-linking agent, 4-20 parts of hydrophilic chain extender, 20-70 parts of hydroxyl-containing organic silicone oil, 1-15 parts of neutralizer, 100-400 parts of water, 10-40 parts of acrylate monomer, and 0.01-0.5 parts of initiator. In the aging-resistant modified waterborne polyurethane of the present invention, the carbon dioxide copolymer polyol has both ether bond and carbonate bond with greater polarity, and the polybutadiene polyol has lower polarity, and is combined together through block copolymerization reaction, so that the internal phase separation of the polyurethane structure is more obvious, and more excellent wear resistance and aging resistance are shown.

Description

Technical Field

[0001] The invention belongs to the field of waterborne polyurethane materials, and particularly relates to an anti-aging modified waterborne polyurethane and a preparation method and application thereof. Background Art

[0002] Common sports floor materials are generally made of polyurethane materials, some of which are silicone-modified waterborne polyurethanes, which are usually prepared by silane coupling agent grafting modification or nano-silicon dioxide modification. Because the hydrolysis of excessive silane coupling agents will cause unstable storage of waterborne polyurethane, the amount of silicone access to the silicone-modified waterborne polyurethane is relatively small, usually less than 2%, and it is difficult to reflect the effect of silicone. In addition, common silicone-modified waterborne polyurethanes still have problems such as poor aging resistance, especially poor wear resistance after aging. A common problem with sports floor topcoats is wear and tear caused by sports, especially after long-term outdoor aging, the strength of the topcoat decreases and the wear resistance also decreases. Summary of the invention

[0003] In view of the problems of the above-mentioned prior art involving the lack of aging resistance and wear resistance of sports floor topcoat, the present invention provides an aging-resistant modified waterborne polyurethane and a preparation method and application thereof.

[0004] To achieve the above purpose, the following technical solutions are specifically included:

[0005] Disclosed is an aging-resistant modified waterborne polyurethane. The raw materials for preparing the polyurethane include the following components in parts by weight: 30-70 parts of carbon dioxide copolymer polyol, 30-70 parts of polybutadiene polyol, 30-70 parts of aliphatic diisocyanate, 1-10 parts of a crosslinking agent, 4-20 parts of a hydrophilic chain extender, 20-70 parts of hydroxyl-containing organic silicone oil, 1-15 parts of a neutralizer, 100-400 parts of water, 10-40 parts of an acrylate monomer, and 0.01-0.5 parts of an initiator; the raw materials for preparing the hydroxyl-containing organic silicone oil include the following components: 8-12 parts of pentaerythritol triacrylate and 20-60 parts of polydimethylmethylhydrogensiloxane.

[0006] The invention adopts pentaerythritol triacrylate and polydimethylmethylhydrogensiloxane to prepare hydroxyl-containing silicone oil with a specific multi-branched structure, and then grafts the prepared branched terminal isocyanate polyurethane prepolymer to form silicone-modified waterborne polyurethane with a specific multi-branched structure, and then introduces acrylate to form a special phase separation structure, so that in the film forming process, the polyurethane and other polar structures are attached to the lower layer, and the acrylate and silicone structure are in the upper layer, which can not only maintain the high strength, good toughness and wear resistance of the polyurethane, but also effectively improve the weather resistance of the waterborne polyurethane, and also ensure the elongation at break, impact absorption and vertical deformation performance of the silicone-modified waterborne polyurethane.

[0007] As a preferred embodiment of the present invention, the raw materials for preparing the aging-resistant modified waterborne polyurethane include the following components in parts by weight: 40-60 parts of carbon dioxide copolymer polyol, 40-60 parts of polybutadiene polyol, 45-65 parts of aliphatic diisocyanate, 1-5 parts of cross-linking agent, 4-15 parts of hydrophilic chain extender, 45-55 parts of hydroxyl-containing silicone oil, 3-11 parts of neutralizer, 150-300 parts of water, 20-30 parts of acrylate monomer, and 0.2-0.3 parts of initiator; the raw materials for preparing the hydroxyl-containing silicone oil include the following components: 10 parts of pentaerythritol triacrylate and 30-50 parts of polydimethylmethylhydrogensiloxane.

[0008] As a preferred embodiment of the present invention, the carbon dioxide copolymer polyol is copolymerized by small molecule polyether, propylene oxide and carbon dioxide, the molecular weight of the carbon dioxide copolymer polyol is 1000g / mol to 4000g / mol, and the molar fraction of the polycarbonate group is 0.1-1.

[0009] As a further preferred embodiment of the present invention, the carbon oxide copolymer polyol is a carbon oxide copolymer diol.

[0010] As a preferred embodiment of the present invention, the number average molecular weight of the polybutadiene polyol is 1000 g / mol to 4000 g / mol.

[0011] As a further preferred embodiment of the present invention, the polybutadiene polyol is polybutadiene diol.

[0012] As a preferred embodiment of the present invention, the aliphatic diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate (hydrogenated MDI).

[0013] As a preferred embodiment of the present invention, the cross-linking agent is at least one of trimethylolpropane, glucose and glycerol.

[0014] As a preferred embodiment of the present invention, the hydrophilic chain extender is at least one of dimethylol propionic acid, dimethylol butyric acid, and sodium aminosulfonate aqueous solution.

[0015] As a preferred embodiment of the present invention, the sodium sulfamate aqueous solution is a sodium sulfamate aqueous solution with a mass percentage of 50%.

[0016] As a preferred embodiment of the present invention, the neutralizing agent is triethylamine.

[0017] As a preferred embodiment of the present invention, the acrylic acid ester monomer is at least one of methyl acrylate, ethyl acrylate, 2-methyl methacrylate, 2-ethyl methacrylate, methyl methacrylate, and butyl acrylate.

[0018] As a preferred embodiment of the present invention, the initiator is ammonium persulfate.

[0019] A method for preparing aging-resistant modified waterborne polyurethane comprises the following steps:

[0020] (1) mixing pentaerythritol triacrylate and polydimethylmethylhydrogensiloxane, heating them for reaction under the condition of a catalyst, and separating the reaction product to obtain the hydroxyl-containing organic silicone oil;

[0021] (2) mixing the carbon dioxide copolymer polyol and the polybutadiene polyol, heating and performing a dehydration reaction to obtain an anhydrous polyol mixture;

[0022] (3) adding aliphatic diisocyanate to the anhydrous polyol mixture to react;

[0023] (4) adding a cross-linking agent and a hydrophilic chain extender to react;

[0024] (5) adding hydroxyl-containing silicone oil to react, adding a solvent, a neutralizing agent and water to disperse, and then removing the solvent to obtain silicone-modified waterborne polyurethane;

[0025] (6) Adding an acrylate monomer and an initiator to the silicone-modified waterborne polyurethane for copolymerization to obtain the aging-resistant modified waterborne polyurethane.

[0026] As a preferred embodiment of the present invention, in step (1), the hydrogen content of the polydimethylmethylhydrogensiloxane is 0.4%-3%.

[0027] As a preferred embodiment of the present invention, in step (1), the catalyst is chloroplatinic acid.

[0028] As a preferred embodiment of the present invention, in step (1), the mass fraction of chloroplatinic acid is 0.01 to 1 part.

[0029] As a preferred embodiment of the present invention, in step (1), the reaction temperature is 70-100° C., and the reaction time is 6-10 h.

[0030] As a further preferred embodiment of the present invention, in step (1), the reaction temperature is 90° C. and the reaction time is 8 h.

[0031] As a preferred embodiment of the present invention, in step (1), the method for separating the reaction product is vacuum distillation, and the specific steps of vacuum distillation are: heating the reaction system to 100-160°C and performing vacuum distillation under negative pressure for 20 to 120 minutes.

[0032] As a further preferred embodiment of the present invention, in step (1), the method for separating the reaction product is vacuum distillation, and the specific steps of vacuum distillation are: heating the reaction system to 120°C and performing vacuum distillation for 30 minutes under a negative pressure of 0.095 MPa.

[0033] As a preferred embodiment of the present invention, in step (2), the specific steps of the dehydration reaction include: carrying out the dehydration reaction for 0.5-3h under negative pressure and a temperature of 70-120°C.

[0034] As a further preferred embodiment of the present invention, in step (2), the specific steps of the dehydration reaction include: carrying out the dehydration reaction for 2 hours under the conditions of a negative pressure of 0.095 MPa and a temperature of 100°C.

[0035] As a preferred embodiment of the present invention, in step (3), the reaction temperature is 75-90° C., and the reaction time is 1-4 h.

[0036] As a further preferred embodiment of the present invention, in step (3), the reaction temperature is 85° C. and the reaction time is 3 h.

[0037] As a preferred embodiment of the present invention, in step (3), the reaction is carried out under the condition of catalysis by a catalyst, and the catalyst is organic bismuth.

[0038] As a preferred embodiment of the present invention, in step (4), the reaction temperature is 60-75°C, and the reaction time is 1-3h.

[0039] As a further preferred embodiment of the present invention, in step (4), the reaction temperature is 70° C. and the reaction time is 2 h.

[0040] As a preferred embodiment of the present invention, in step (5), the reaction temperature is 60-80°C, and the reaction time is 1-5h.

[0041] As a further preferred embodiment of the present invention, in step (5), the reaction temperature is 70° C. and the reaction time is 3 h.

[0042] As a preferred embodiment of the present invention, in step (5), the dispersion temperature is 10-60°C, the dispersion time is 1-30 min, and the dispersion speed is 1000-2000 rpm.

[0043] As a further preferred embodiment of the present invention, in step (5), the dispersion temperature is 50° C., the dispersion time is 15 min, and the dispersion speed is 1500 rpm.

[0044] As a preferred embodiment of the present invention, in step (5), the solvent is acetone or butanone.

[0045] As a preferred embodiment of the present invention, in step (6), the temperature of the copolymerization reaction is 70-100° C., and the time of the copolymerization reaction is 1-5 h.

[0046] As a further preferred embodiment of the present invention, in step (6), the temperature of the copolymerization reaction is 75° C., and the time of the copolymerization reaction is 5 h.

[0047] The present invention also provides an application of the aging-resistant modified waterborne polyurethane in the preparation of waterborne polyurethane coatings.

[0048] A waterborne polyurethane coating, the preparation raw materials of which include the following components in parts by weight: 80-120 parts of the anti-aging modified waterborne polyurethane, 10-50 parts of fillers, and 0.1-5 parts of waterborne additives.

[0049] As a further preferred embodiment of the present invention, the filler is at least one of talc powder with a mesh size of 400 to 1250 mesh, heavy calcium carbonate, kaolin, and titanium dioxide.

[0050] As a preferred embodiment of the present invention, the aqueous auxiliary agent is at least one of a defoamer, a wetting agent, a preservative, a thickener, and a pH adjuster.

[0051] The raw materials for preparing the waterborne polyurethane coating include the following components in parts by weight: 100 parts of the anti-aging modified waterborne polyurethane, 15 parts of fillers, 0.3 parts of dispersants, 0.4 parts of wetting agents, 0.2 parts of defoamers, 0.1 parts of preservatives, and 1 part of thickeners.

[0052] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts pentaerythritol triacrylate and polydimethylmethylhydrogensiloxane to prepare hydroxyl-containing silicone oil with a specific multi-branched structure, and then grafts with the prepared branched terminal isocyanate polyurethane prepolymer to form a silicone-modified waterborne polyurethane with a specific multi-branched structure, and then introduces acrylate to form a special phase separation structure, so that in the film forming process, the polyurethane and other polar structures are attached to the lower layer, and the acrylate and silicone structure are in the upper layer, which can not only maintain the high strength, good toughness and wear resistance of the polyurethane, but also effectively improve the weather resistance of the waterborne polyurethane, and also ensure the elongation at break, impact absorption and vertical deformation performance of the silicone-modified waterborne polyurethane. At the same time, the modified polyurethane structure is different from the general polyurethane, because its carbon dioxide copolymer polyol has both ether bonds and carbonate bonds and has a large polarity, and the polybutadiene polyol has a low polarity. Through block copolymerization, they are combined together, so that the internal phase separation of the polyurethane structure is more obvious, and more excellent wear resistance and aging resistance are exhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic diagram of the synthesis of branched hydroxyl-containing organic silicone oil from polydimethylmethylhydrogensiloxane and pentaerythritol triacrylate in Example 1-3. DETAILED DESCRIPTION

[0054] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below through specific embodiments.

[0055] The sources of some raw material information used in the following examples and comparative examples are as follows:

[0056] Dispersant: Dow dispersant 1124; Wetting agent: Dow wetting agent BD109; Defoaming agent: Nopco NXZ defoaming agent; Preservative: Dow preservative 631; Thickener: Rohm and Haas thickener 8w mixed.

[0057] The carbon dioxide copolymer polyol, polybutadiene polyol and polyether polyol all use difunctional polyol copolymers, namely, carbon dioxide copolymer diol, polybutadiene diol and polyether diol, which are commercially available, wherein the molar fraction of the polycarbonate group of the carbon dioxide copolymer diol is 0.3.

[0058] The dispersants, wetting agents, defoamers, preservatives and thickeners used in the examples and comparative examples are all of the same type.

[0059] Example 1

[0060] The aging-resistant modified waterborne polyurethane of this embodiment includes the following raw material components in parts by weight: 40 parts of carbon dioxide copolymer polyol, 60 parts of polybutadiene polyol, 45 parts of aliphatic diisocyanate, 5 parts of cross-linking agent, 15 parts of hydrophilic chain extender, 55 parts of hydroxyl-containing silicone oil, 11 parts of neutralizer, 300 parts of water, 30 parts of acrylate monomer, and 0.2 parts of initiator; the raw materials for preparing the hydroxyl-containing silicone oil include the following components: 10 parts of pentaerythritol triacrylate and 50 parts of polydimethylmethylhydrogensiloxane.

[0061] A method for preparing aging-resistant modified waterborne polyurethane comprises the following steps:

[0062] (1) adding 10 parts by mass of pentaerythritol triacrylate and 50 parts of polydimethylmethylhydrogensiloxane (hydrogen content 0.78%-0.82%) to a reaction kettle under stirring, and then adding 0.25 parts of chloroplatinic acid, heating to 90° C. for reaction for 8 hours, and then heating to 120° C. for separation of the reaction product by vacuum distillation at a negative pressure of 0.095 MPa for 30 minutes to obtain the hydroxyl-containing organic silicone oil;

[0063] (2) Add 40 parts by mass of carbon dioxide copolymer polyol (Mn=3000 g / mol) and 60 parts of polybutadiene polyol (Japan Soda, Mn=3000 g / mol) to the reactor, heat to 100° C., and dehydrate for 2 h under a negative pressure of 0.095 MPa to obtain an anhydrous polyol mixture;

[0064] (3) adding 45 parts of isophorone diisocyanate and 0.08 parts of organic bismuth to the anhydrous polyol mixture, and reacting at 85° C. for 3 hours;

[0065] (4) lowering the temperature of the system to 70°C, adding 5 parts of glycerol and 15 parts of dimethylol propionic acid, and reacting for 2 hours;

[0066] (5) controlling the temperature of the system at 70° C., adding 55 parts of the hydroxyl-containing silicone oil prepared in (1) above, reacting for 3 h, cooling the system temperature to 50° C., adding 50 parts of acetone and 11 parts of triethylamine, adding 300 parts of deionized water under high-speed stirring, dispersing for 15 min, and then removing acetone to obtain silicone-modified waterborne polyurethane;

[0067] (6) Add 15 parts of methyl methacrylate and 15 parts of butyl acrylate to the organosilicon-modified waterborne polyurethane, raise the temperature to 75° C., add 0.2 parts of ammonium persulfate and carry out copolymerization for 5 hours to obtain the aging-resistant modified waterborne polyurethane.

[0068] A method for preparing a waterborne polyurethane coating comprises the following steps: mixing, by mass, 100 parts of the aging-resistant modified waterborne polyurethane prepared in the above step (6), 15 parts of 1250-mesh kaolin, 0.3 parts of a dispersant, 0.4 parts of a wetting agent, 0.2 parts of a defoaming agent, 0.1 parts of a preservative and 1 parts of a thickener, and stirring the mixture to obtain a waterborne polyurethane coating.

[0069] Example 2

[0070] Compared with Example 1, the difference is that the carbon dioxide copolymer polyol is 60 parts and the polybutadiene polyol is 40 parts.

[0071] Example 3

[0072] Compared with Example 1, the difference of this example is that the hydroxyl-containing organic silicone oil in step (5) is 70 parts.

[0073] Comparative Example 1

[0074] Compared with Example 1, the difference is that in step (2), 40 parts of carbon dioxide copolymer polyol and 60 parts of polybutadiene polyol are replaced by 100 parts of polyether polyol (Mn=2000 g / mol).

[0075] Comparative Example 2

[0076] Compared with Example 1, the difference is that step (6) is not performed, that is, acrylic acid monomer is not added for polymerization.

[0077] Comparative Example 3

[0078] Compared with Example 1, the difference is that step (1) is not performed, and the hydroxyl-containing organic silicone oil is replaced by silane coupling agent KH550.

[0079] The waterborne polyurethane coatings prepared in the examples and comparative examples were coated on glass plates and dried at room temperature for 7 days to test the initial wear resistance. Three parallel samples were tested and the test results were averaged. The wear resistance test standard refers to GB / T1768-1979.

[0080] Water-based coatings will degrade in performance and affect usability when exposed to light outdoors. Since the natural aging cycle of the material is long, artificial accelerated aging is used. This test is based on GB / T16422.3-2014 "Plastic Laboratory Light Source Exposure Test Method Part 3: Fluorescent UV Lamp". The samples are prepared as above, UV aged for 14 days, and then tested for wear resistance. Three parallel samples are tested and the test results are averaged.

[0081] Table 1 Abrasion resistance of coatings of waterborne polyurethane coatings of Examples and Comparative Examples

[0082]

[0083]

[0084] (1) Example 2 has a higher content of carbon dioxide copolymer polyol than Example 1. The carbon dioxide copolymer polyol contains a large amount of carbonate bonds, has a stronger polarity, and has a higher cohesive energy. Therefore, the wear resistance of Example 2 and the wear resistance after exposure to sunlight are better than those of Example 1.

[0085] (2) Compared with Example 1, in Example 3, the content of hydroxyl-containing silicone is increased in the waterborne polyurethane stage, and a large number of silicone side chains are introduced. The cohesion is reduced to a certain extent, resulting in a decrease in wear resistance, but relative wear is reduced.

[0086] (3) Compared with Example 1, Comparative Example 1 uses polyether polyol, which has low cohesive energy, and the resulting coating has poor wear resistance. In addition, its structure contains a large number of side methyl groups, which is unstable and easily aged.

[0087] (4) Compared with Example 1, no acrylic monomer is added in Comparative Example 2, and no interpenetrating network cross-linking structure is formed inside the coating, resulting in poor wear resistance of the coating. In addition, the coating lacks the relatively aging-resistant acrylic resin component, and the aging resistance effect of the coating is also poor.

[0088] (5) Compared with Example 1, the coating of Comparative Example 3, which contains the silane coupling agent, not only lacks a dendritic structure, but also has a reduced molecular weight, making it difficult for the coating to achieve good wear resistance.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An aging-resistant modified waterborne polyurethane, characterized in that: The raw materials for preparing the hydroxyl-containing silicone oil include the following components in parts by weight: 30-70 parts of carbon dioxide copolymer polyol, 30-70 parts of polybutadiene polyol, 30-70 parts of aliphatic diisocyanate, 1-10 parts of a crosslinking agent, 4-20 parts of a hydrophilic chain extender, 20-70 parts of hydroxyl-containing silicone oil, 1-15 parts of a neutralizing agent, 100-400 parts of water, 10-40 parts of an acrylate monomer, and 0.01-0.5 parts of an initiator; the raw materials for preparing the hydroxyl-containing silicone oil include the following components: 8-12 parts of pentaerythritol triacrylate and 20-60 parts of polydimethylmethylhydrogensiloxane.

2. The aging-resistant modified waterborne polyurethane according to claim 1, characterized in that: The raw materials for preparing the aging-resistant modified waterborne polyurethane include the following components in parts by weight: 40-60 parts of carbon dioxide copolymer polyol, 40-60 parts of polybutadiene polyol, 45-65 parts of aliphatic diisocyanate, 1-5 parts of a crosslinking agent, 4-15 parts of a hydrophilic chain extender, 45-55 parts of hydroxyl-containing silicone oil, 3-11 parts of a neutralizer, 150-300 parts of water, 20-30 parts of an acrylate monomer, and 0.2-0.3 parts of an initiator; the raw materials for preparing the hydroxyl-containing silicone oil include the following components: 10 parts of pentaerythritol triacrylate and 30-50 parts of polydimethylmethylhydrogensiloxane.

3. The aging-resistant modified waterborne polyurethane according to claim 1, characterized in that: Includes at least one of the following (a)-(e): (a) The carbon dioxide copolymer polyol is copolymerized by small molecule polyether, propylene oxide and carbon dioxide, and the molecular weight of the carbon dioxide copolymer polyol is 1000 g / mol to 4000 g / mol; (b) the number average molecular weight of the polybutadiene polyol is 1000 g / mol to 4000 g / mol; (c) the aliphatic diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate and hydrogenated diphenylmethane diisocyanate; (d) the cross-linking agent is at least one of trimethylolpropane, glucose and glycerol; (e) The hydrophilic chain extender is at least one of dimethylol propionic acid, dimethylol butyric acid, and sodium aminosulfonate aqueous solution.

4. The aging-resistant modified waterborne polyurethane according to claim 1, characterized in that: The acrylic acid ester monomer is at least one of methyl acrylate, ethyl acrylate, 2-methyl methacrylate, 2-ethyl methacrylate, methyl methacrylate, and butyl acrylate.

5. The aging-resistant modified waterborne polyurethane according to claim 1, characterized in that: The initiator is ammonium persulfate; the neutralizer is triethylamine.

6. The method for preparing the aging-resistant modified waterborne polyurethane according to any one of claims 1 to 5, characterized in that: The steps include: (1) mixing pentaerythritol triacrylate and polydimethylmethylhydrogensiloxane, heating them for reaction under the condition of a catalyst, and separating the reaction product to obtain the hydroxyl-containing organic silicone oil; (2) mixing the carbon dioxide copolymer polyol and the polybutadiene polyol, heating and performing a dehydration reaction to obtain an anhydrous polyol mixture; (3) adding aliphatic diisocyanate to the anhydrous polyol mixture to react; (4) adding a cross-linking agent and a hydrophilic chain extender to react; (5) adding hydroxyl-containing silicone oil to react, adding a solvent, a neutralizing agent and water to disperse, and then removing the solvent to obtain silicone-modified waterborne polyurethane; (6) Adding an acrylate monomer and an initiator to the silicone-modified waterborne polyurethane for copolymerization to obtain the aging-resistant modified waterborne polyurethane.

7. The method for preparing the aging-resistant modified waterborne polyurethane according to claim 6, characterized in that: In step (1), the hydrogen content of the polydimethylmethylhydrogensiloxane is 0.4%-3%; in step (1), the catalyst is chloroplatinic acid.

8. The method for preparing the aging-resistant modified waterborne polyurethane according to claim 6, characterized in that: Include at least one of the following AHs: A. In step (1), the reaction temperature is 70-100°C and the reaction time is 6-10h; B. In step (1), the method for separating the reaction product is vacuum distillation, and the specific steps of vacuum distillation are: heating the reaction system to 100-160° C. and vacuum distilling for 20-120 min under negative pressure; C. In step (2), the specific steps of the dehydration reaction include: carrying out the dehydration reaction for 0.5-3h under negative pressure and a temperature of 70-120°C; D. In step (3), the reaction temperature is 75-90°C and the reaction time is 1-4h; E. In step (4), the reaction temperature is 60-75°C and the reaction time is 1-3h; F. In step (5), the reaction temperature is 60-80°C and the reaction time is 1-5h; G. In step (5), the dispersion temperature is 10-60°C, the dispersion time is 1-30min, and the dispersion speed is 1000-2000rpm; H. In step (6), the copolymerization reaction temperature is 70-100° C., and the copolymerization reaction time is 1-5 h.

9. A waterborne polyurethane coating, characterized in that: The raw materials for its preparation include the following components in parts by weight: 80-120 parts of the anti-aging modified waterborne polyurethane according to any one of claims 1 to 5, 10-50 parts of fillers, and 0.1-5 parts of waterborne additives.

10. The waterborne polyurethane coating according to claim 9, characterized in that: The filler is at least one of 400-1250 mesh talc, heavy calcium carbonate, kaolin, and titanium dioxide; the aqueous additive is at least one of a defoamer, a wetting agent, a preservative, a thickener, and a pH regulator.

Images