Waterborne polyurethane coating, preparation method and coating

Abstract

The invention provides a waterborne polyurethane coating, a preparation method and a coating. The water-based polyurethane coating is prepared from the following raw materials: silane modified water-based polyurethane emulsion; a silane modified anti-UV nano filler; the invention discloses a silane-modified anti-UV (ultraviolet) nano-filler, which comprises a silane-modified waterborne polyurethane emulsion, a silane-modified anti-UV nano-filler and an additive, the silane-modified waterborne polyurethane emulsion is obtained by reaction of silane-modified composite isocyanate and polyether polyol, and the silane-modified waterborne polyurethane emulsion and the silane-modified anti-UV nano-filler have silane groups, epoxy groups, vinyl groups and optional ureido groups.

Description

Technical Field

[0001] The present invention relates to the field of chemical materials, and in particular to a waterborne polyurethane coating, a preparation method and a coating. Background Art

[0002] Traditional solvent-based or oil-based polyurethane waterproof coatings have the disadvantages of large volatile organic compound (VOC) emissions, strong odor, residual toxic and hazardous substances, carbon dioxide generated during the curing process, and uneven quality. These problems or shortcomings lead to environmental pollution, threats to people's health, and the buildings that apply the coating are prone to quality problems due to the waterproof quality of the waterproof coating. Therefore, environmentally friendly, high-performance, widely used, fast curing at room temperature, and low-cost polyurethane waterproof coatings are currently the development direction of polyurethane waterproof coatings.

[0003] Compared with traditional polyurethane waterproof coatings, waterborne polyurethane waterproof coatings have the advantages of safety, environmental protection, low VOC, and low odor. The formed coating has good flexibility, adhesion, and chemical resistance. And compared with oily polyurethane coatings, waterborne coatings have good adhesion on the surfaces of cement-based, stone-based, metal and other substrates. After the coating is dried and cured, an elastic coating of a certain thickness can be formed on the surface of the structure. The coating has the characteristics of waterproof, anti-ultraviolet aging, chemical corrosion resistance, high tensile strength, and high elongation. In particular, single-component waterborne polyurethane waterproof coatings are safe, environmentally friendly, easy to use, and have the characteristics of high strength, large elongation at break, good water resistance, etc. They can be dried at room temperature and have strong adaptability to deformation of the base layer.

[0004] However, the solid content, weather resistance and other properties of current waterborne polyurethane coatings still need to be further improved. Summary of the invention

[0005] The present disclosure aims to provide a waterborne polyurethane coating, a preparation method and a coating to solve or alleviate one or more technical problems in the related art.

[0006] As a first aspect of an embodiment of the present disclosure, the present disclosure provides a waterborne polyurethane coating. The raw materials for forming the waterborne polyurethane coating include:

[0007] Silane modified waterborne polyurethane emulsion;

[0008] Silane modified UV resistant nanofillers; and

[0009] additive,

[0010] The silane-modified waterborne polyurethane emulsion is obtained by reacting a silane-modified complex isocyanate and a polyether polyol, and the silane-modified waterborne polyurethane emulsion and the silane-modified anti-UV nanofiller contain a silane group, an epoxy group, a vinyl group, and optionally a urea group.

[0011] Furthermore, the silane-modified waterborne polyurethane emulsion and the silane-modified UV-resistant nanofiller are obtained by modification with a modifier, wherein the modifier includes a silane coupling agent, and the silane coupling agent includes any one or more of WD50, KH550, KH560, KH570, and IPST.

[0012] Furthermore, the silane coupling agent includes multiple coupling agents.

[0013] Furthermore, the mass ratio of isocyanate to the silane coupling agent in the raw material for forming the composite isocyanate is (7-10): (0.8-2).

[0014] Furthermore, the raw materials for forming the waterborne polyurethane coating further include hydrolysis coupling gel, and the hydrolysis coupling gel is formed by hydrolysis reaction of multiple silane coupling agents.

[0015] Furthermore, the silane-modified anti-UV nanofiller is formed of nanoparticles and a modifier, the nanoparticles include at least one of titanium dioxide, cerium oxide, zinc oxide, tungsten oxide, silicon oxide and vanadium oxide, and the modifier includes a variety of silane coupling agents.

[0016] Furthermore, the additive comprises a composite anti-sagging agent thixotropic paste, and optionally at least one of a water retaining agent, a mildew preventer, a film former, a dispersant, a defoaming agent and a filler, wherein the composite anti-sagging agent thixotropic paste comprises nano calcium, gas silica, wax powder and bentonite.

[0017] Furthermore, in the raw materials for forming the silane-modified waterborne polyurethane emulsion, the mass ratio of the complex isocyanate and the polyether polyol is (3-8): (15-30).

[0018] Furthermore, the waterborne polyurethane coating satisfies at least one of the following conditions:

[0019] The viscosity of the waterborne polyurethane coating is 3500-8400 mPa.s;

[0020] The solid content of the waterborne polyurethane coating is not less than 75%.

[0021] In another aspect of the present disclosure, the present disclosure provides a method for preparing the aforementioned waterborne polyurethane coating. The method comprises:

[0022] Forming a composite isocyanate, wherein the composite isocyanate is formed by reacting an isocyanate and a modifier containing a silane at a temperature not higher than 20 degrees Celsius;

[0023] forming a silane-modified waterborne polyurethane emulsion, wherein the silane-modified waterborne polyurethane emulsion is formed by adding a polyether polyol to the composite isocyanate;

[0024] forming a silane-modified anti-UV nanofiller, wherein the modified anti-UV nanofiller is obtained by treating nanoparticles with the modifier,

[0025] The silane-modified waterborne polyurethane emulsion, the silane-modified anti-UV nanofiller and the additive are mixed and subjected to a degassing treatment to obtain the waterborne polyurethane coating.

[0026] Further, the method satisfies at least one of the following conditions:

[0027] When forming the composite isocyanate, the isocyanate and the first modifier are added to cold water and the temperature is maintained at no more than 20 degrees Celsius, and then the second modifier to the fourth modifier are sequentially added dropwise, reacted for 0.5-1.5 hours and the temperature is controlled to be no more than 20 degrees Celsius, and the mass ratio of the isocyanate, the first modifier, the second modifier, the third modifier and the fourth modifier is (8-10): (0.3-0.8): (0.05-0.2): (0.1-0.3): (0.2-0.5);

[0028] When forming the silane-modified waterborne polyurethane emulsion, the polyether polyol is added dropwise to the composite isocyanate and reacted for 2-4 hours, and a solvent is added at least once during the reaction, wherein the solvent includes acetone;

[0029] The additive comprises a composite anti-sagging agent thixotropic paste, and the composite anti-sagging agent thixotropic paste is obtained by physically mixing nano calcium, gas silicon, wax powder and bentonite.

[0030] The method further includes the operation of forming a hydrolyzable coupling agent gel, and mixing the hydrolyzable coupling agent gel with the silane-modified aqueous polyurethane emulsion, the silane-modified anti-UV nanofiller and the additive for degassing. The operation of forming the hydrolyzable coupling agent gel includes mixing and stirring a plurality of silane coupling agents and water in a closed container to perform a hydrolysis reaction.

[0031] In yet another aspect of the present disclosure, the present disclosure provides a coating, which is formed by using the above-mentioned waterborne polyurethane coating.

[0032] The waterborne polyurethane coating and preparation method thereof proposed in the present disclosure adopt a silane-modified waterborne polyurethane emulsion and a silane-modified UV-resistant nanofiller in combination with an appropriate additive system, so as to obtain a coating having good adhesion to a variety of substrates with a high solid content and an extremely low volatile solvent content, and the obtained coating has good weather resistance and mechanical properties.

[0033] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present disclosure will be readily apparent from the following detailed description. DETAILED DESCRIPTION

[0034] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure, and different embodiments may be combined arbitrarily without conflict. Therefore, the following description is considered to be illustrative and non-restrictive in nature.

[0035] In the first aspect of the present disclosure, the present disclosure proposes a waterborne polyurethane coating. The raw materials for forming the waterborne polyurethane coating include silane-modified waterborne polyurethane emulsion, silane-modified anti-UV nanofiller and additives. The silane-modified waterborne polyurethane emulsion is obtained by reacting a silane-modified complex isocyanate and a polyether polyol, and the silane-modified waterborne polyurethane emulsion and the silane-modified anti-UV nanofiller have a silane group, an epoxy group, a vinyl group, and optionally a urea group. The waterborne polyurethane coating has at least one of the advantages of high solid content, safety and environmental protection, moderate viscosity, good weather resistance, excellent mechanical properties, and good wettability to a variety of substrates.

[0036] For ease of understanding, the following is a brief description of the principle by which the coating can achieve the aforementioned beneficial effects:

[0037] As mentioned above, the inventors have found that conventional waterborne polyurethane uses water instead of organic solvents as a dispersion medium, which has the advantages of being non-toxic, non-flammable, non-polluting the environment, and saving energy. However, conventional waterborne polyurethane generally has an extremely low solid content of about 30%, and contains residual monomers and solvents, and the film thickness has a certain taste. And because an emulsifier is required in the system, conventional products of this type are not resistant to blisters and are easy to absorb water and swell: waterborne polyurethane resins usually need to use various anions, cations or non-ions as emulsifiers. Therefore, there are hydrophilic groups in the obtained polyurethane structure, which makes the water resistance, solvent resistance, heat resistance and gloss of the coating poor, strictly limiting its scope of use. In addition, the polyurethane coating obtained by the above method belongs to water volatilization film curing, non-reactive cross-linking, low cross-linking degree, generally low physical properties, easy to absorb water, high water absorption, poor water resistance, low solid content, and poor long-term adhesion to the base layer. Generally, a primer is required before the construction of the waterborne polyurethane coating.

[0038] The present invention adopts silane-modified waterborne polyurethane emulsion and the silane-modified anti-UV nanofiller to form a waterborne polyurethane coating, and can obtain a coating with good water resistance, weather resistance, oxidation resistance, air permeability, low polarity and low surface performance through silane modification. In addition, due to the relatively low compatibility of silicone and polyurethane, siloxane will migrate to the surface of the film and enrich on the surface of the waterborne polyurethane film, which can give the modified polymer low surface energy and improve the water resistance, chemical resistance, high and low temperature resistance, weather resistance and other properties of the paint film. The silicone material is mixed with the silicone material by physical method to reduce the surface performance of the coating film and improve the comprehensive performance.

[0039] In the waterborne polyurethane coating disclosed in the present invention, the silane-modified waterborne polyurethane emulsion and the silane-modified anti-UV nanofiller are obtained by modification treatment using a modifier. The modifier contains at least one of a silane group, an epoxy group, and a vinyl group. The modifier can react with the raw material isocyanate in the waterborne polyurethane emulsion to generate a urea group. The above-mentioned group is conducive to the coating forming a moderate viscosity and maintaining a high solid content. In addition, the silane-modified group is also conducive to improving the weather resistance and mechanical properties of the coating formed by the coating due to the aforementioned migration and enrichment process.

[0040] According to some examples of the present invention, the aforementioned modifier includes a silane coupling agent. The specific type of the silane coupling agent is not particularly limited, for example, it can include any one or more of WD50, KH550, KH560, KH570, and IPST. In some examples, the modifier may include two or more of the above silane coupling agents.

[0041] According to some examples of the present invention, the composite isocyanate can be obtained by reacting the isocyanate with the silane coupling agent in advance. The mass ratio of the isocyanate and the silane coupling agent in the raw material for forming the composite isocyanate can be (7-10): (0.8-2). The above ratio is conducive to the formation of isocyanate fully modified by the silane modifier, and the content and ratio of the urea group, epoxy group, unsaturated group and silane group in the obtained composite isocyanate are relatively moderate, which is conducive to the formation of a silane-modified waterborne polyurethane emulsion with good polymerization degree, viscosity and network structure. More specifically, a variety of silane coupling agents can be used in this step, such as IPTS, KH550, KH560 and KH570. Among them, the mass ratio of TDI: IPTS: KH550: KH560: KH570 can be 9: 0.5: 0.1: 0.2: 0.3.

[0042] In the raw materials of the silane-modified waterborne polyurethane emulsion, the mass ratio of the complex isocyanate to the polyether polyol is not particularly limited, and can be, for example, (3-8): (15-30).

[0043] In some examples of the present invention, the raw materials for forming the waterborne polyurethane coating may further include a hydrolysis coupling gel. The hydrolysis coupling gel is formed by a hydrolysis reaction of a plurality of silane coupling agents, and the ratio of the silane coupling agent to water may be (50-70):1. In other words, the raw materials of the waterborne polyurethane coating may contain a gel system formed by a silane coupling agent and water. Allowing a portion of the silane coupling agent and water to form a gel in advance is conducive to reducing the reaction rate of the system and preventing the formation of components with excessive molecular weight, resulting in a decrease in the overall viscosity of the system. The hydrolysis coupling agent gel may contain a plurality of silane coupling agents, for example, KH550, KH560, and KH570. In a specific embodiment, the mass ratio of KH550:KH560:KH570:water may be 1:2:3:0.1.

[0044] The hydrolytic coupling gel can be added in the step of forming a silane-modified waterborne polyurethane emulsion. In order to further improve the performance of the coating, solvents such as acetone, as well as chain extenders and / or hydrophilic chain extenders including but not limited to sodium ethylenediamine ethanesulfonate, dimethylol propionic acid and 1-4-butanediol can be added while forming the silane-modified waterborne polyurethane emulsion. In a specific embodiment, the mass ratio of hydrolytic coupling gel: acetone: sodium ethylenediamine ethanesulfonate: dimethylol propionic acid: 1-4-butanediol can be 20:5:0.2:10::2:1:0.5.

[0045] In some examples of the present invention, silane-modified anti-UV nanofillers can be formed by nanoparticles and modifiers. In the present invention, the specific types of nanoparticles are not particularly limited, as long as they have certain anti-UV properties. For example, the nanoparticles may include at least one of titanium dioxide, cerium oxide, zinc oxide, tungsten oxide, silicon oxide and vanadium oxide, and the modifier includes a variety of silane coupling agents. The modifier here can be selected from the aforementioned silane coupling agents. The silane modifier forming the silane-modified anti-UV nanofiller may be the same as the modifier forming the composite isocyanate, or it may be different. In the silane-modified anti-UV nanofiller, the mass ratio of nanoparticles and modifiers can be (8-10): (0.03-0.1).

[0046] In order to further improve the performance of the coating, the raw materials for forming the waterborne polyurethane coating may further include one or more additives. For example, the additives include a composite anti-sagging agent thixotropic paste, and optionally at least one of a water retaining agent, a mildewproof agent, a film former, a dispersant, a defoamer, and a filler. The specific composition of the water retaining agent, mildewproof agent, film former, dispersant, defoamer, and filler is not particularly limited, and those skilled in the art can select according to actual needs.

[0047] According to an embodiment of the present invention, a composite anti-sagging agent thixotropic paste includes nano calcium, gas silica, wax powder and bentonite. The composite anti-sagging agent thixotropic paste of the above components is particularly suitable for a silane-modified polyurethane emulsion system. Specifically, nano calcium and gas silica are conducive to forming more hydrogen bonds in the system, thereby constructing a three-dimensional network structure to enhance the mechanical properties and weather resistance of the coating formed by the coating. Moreover, the above two components have good silane affinity, which is conducive to forming a more uniform system. Bentonite and wax powder can be fully expanded in solvents such as ethanol and water, which is also conducive to forming a more three-dimensional structure, avoiding local excessive polymerization to form macromolecules with a molecular weight exceeding expectations.

[0048] The waterborne polyurethane coating meets at least one of the following conditions:

[0049] The viscosity of the waterborne polyurethane coating is 3500-8400 mPa.s;

[0050] The solid content of the waterborne polyurethane coating is not less than 75%.

[0051] In some specific embodiments, the weight parts of each component in the waterborne polyurethane coating can be shown in the following Table 1:

[0052] Table 1

[0053] Silane modified waterborne polyurethane emulsion 30-50 parts by weight Partially hydrolyzed silane gel 0.5-2 parts by weight Silane-treated light-controlled nanomaterials 10-20 parts by weight Dispersants 0.1-0.3 parts by weight Defoaming agent 0.1-0.3 parts by weight filler 25-45 parts by weight Composite anti-sagging agent thixotropic paste 1-5 parts by weight Water Retention Agent 0.3-1 parts by weight Antifungal agent 0.05-0.1 parts by weight Wetting Agents 0.05-0.1 parts by weight

[0054] In general, the coatings provided in the present disclosure may have at least one of the following advantages:

[0055] 1. The solid content of this product is as high as 75% or more;

[0056] 2. It has long-lasting adhesion with various bases, especially concrete bases, and has excellent bonding performance on wet bases and good water resistance. The bonding strength after immersion in water reaches more than 80%, reaching 1MPa, and the wet base surface is more than 0.5MPa. The immersion bonding retention rate reaches more than 80%;

[0057] 3. Excellent physical properties, reaching more than 6MPa, and elongation of more than 450%, especially suitable for outdoor concrete surface waterproofing, decoration and protection.

[0058] 4. Water absorption rate ≤5%, high density of coating film.

[0059] 5. The polysilane in the raw materials is polymerized with polyurethane in steps. The formed coating can be exposed to direct ultraviolet rays and thermal oxygen aging for a long time. It has passed the 2500h ultraviolet aging test without color change and no powdering or cracks on the surface.

[0060] 6. The obtained coating has excellent long-lasting adhesion to various base layers and has large cohesive energy. The material has excellent tensile properties and greatly improved water resistance.

[0061] 7. Single-component material, no need for machine stirring, saving labor and cost.

[0062] 8. The formula is water-based, environmentally friendly, has extremely low VOC content, and low viscosity, which is conducive to scraping construction and on-site application.

[0063] The viscosity of this single-component solvent-free silane-modified polyurethane is between 3500-8400mPa.s. It is easy to construct and can be constructed 1mm at a time without flowing. It is water-based, safe and environmentally friendly. It has a large wetting ability for the base layer and strong adhesion. It has good bonding to various substrates and can pass the 2500h UV aging test. The test results are shown in Table 2 below.

[0064] Table 2

[0065]

[0066]

[0067] In another aspect of the present disclosure, the present disclosure proposes a method for preparing the aforementioned coating. Specifically, the method includes the following operations: forming a composite isocyanate, wherein the composite isocyanate is formed by reacting an isocyanate and a modifier containing a silane under a condition not higher than 20 degrees Celsius. Forming a silane-modified waterborne polyurethane emulsion, wherein the silane-modified waterborne polyurethane emulsion is formed by adding a polyether polyol to the composite isocyanate. Forming a silane-modified anti-UV nanofiller, wherein the modified anti-UV nanofiller is obtained by treating nanoparticles with the modifier. Subsequently, the silane-modified waterborne polyurethane emulsion, the silane-modified anti-UV nanofiller and the additive are mixed and degassed to obtain the waterborne polyurethane coating.

[0068] Specifically, in the step of forming the composite isocyanate, isocyanate and a modifier may be added to cold water. The modifier may be a variety of the aforementioned silane coupling agents. For example, the first modifier may be added first and the temperature may be kept not higher than 20 degrees Celsius, and then the second modifier to the fourth modifier may be added dropwise in sequence, reacted for 0.5-1.5 hours and the temperature may be controlled not higher than 20 degrees Celsius. The first to fourth modifiers may be selected from any component of the aforementioned silane coupling agents. Specifically, the first modifier may be IPTS, the second modifier may be KH550, the third modifier may be KH560, and the fourth modifier may be KH570. The mass ratio of isocyanate, the first modifier, the second modifier, the third modifier and the fourth modifier is (8-10): (0.3-0.8): (0.05-0.2): (0.1-0.3): (0.2-0.5).

[0069] Specifically, the additives may include a composite anti-sagging agent thixotropic paste, and various additives contained in the aforementioned water-based polyurethane coating. Among them, the composite anti-sagging agent thixotropic paste can be obtained by physically mixing nano calcium, gas silica, wax powder and bentonite. For example, the above components can be added to water for physical stirring to obtain a material with a particle size of less than 40 microns. The mass ratio of water, nano calcium, gas silica, wax powder and bentonite can be (120-150): (180-220): (2-5): 1:1.

[0070] In a specific example of the present disclosure, the method may include the following steps:

[0071] 1. Formation of composite reaction silane isocyanate:

[0072] Add appropriate amount of isocyanate TDI and first modifier, such as IPTS, to the reactor into which cooling water is introduced, and keep the temperature below 20°C, then slowly drop an appropriate amount of second modifier WD50 or KH550, drip it for 20-40 minutes, stir and control the temperature below 20°C to react for about 1 hour, then drop an appropriate amount of third modifier KH560, stir and control the temperature below 20°C to react for about 1 hour, finally drop the fourth modifier KH570, stir and control the temperature below 20°C to react for 1 hour, and finally the material contains silane groups and epoxy groups. Among them, the mass ratio of TDI (isocyanate): IPTS: KH550 (WD50): KH560: KH570 can be 9: 0.5: 0.1: 0.2: 0.3. The above reaction conditions are conducive to controlling the reaction rate within a more desired range, and thus obtaining a coating with good viscosity and molecular weight distribution.

[0073] 2. Hydrolysis coupling agent gel:

[0074] Add appropriate amount of silane modifier, such as KH550, KH560, KH570 coupling agent, into the reactor, control the temperature at 60℃, then drop appropriate amount of distilled water, stir and control the temperature below 60℃ to react for about 1 hour. The mass ratio of KH550:KH560:KH570:water is 1:2:3:0.1.

[0075] 3. Water-based silane-modified polyurethane emulsion:

[0076] The composite isocyanate obtained in step 1 is added to the reactor, polyether polyol is added dropwise to the reactor, and the reaction is carried out at about 60-70°C for about 4 hours. During the reaction, an appropriate amount of acetone is added twice to reduce the viscosity of the system. Finally, the isocyanate group is measured to reach the designed endpoint value. The obtained hydrophilic modified polyurethane prepolymer is chain extended with 1-4 butanediol for about 2-3 hours, and an appropriate amount of sodium ethylenediamine ethanesulfonate and dimethylol propionic acid (DMPA) are added. Finally, the temperature is lowered to 30°C, deionized water is added, and emulsification is carried out on a high-speed disperser to obtain a translucent aqueous polyurethane dispersion, and then the acetone is removed at 30-40°C under a vacuum of -0.1MPa, and the hydrolysis coupling agent gel in step 2 is added and stirred evenly. The mass ratio of polyether polyol: composite silane isocyanate: hydrolyzed coupling agent gel: acetone: sodium ethylenediamine sulfonate: dihydroxymethyl propionic acid: 1-4-butanediol can be 20:5:0.2:10::2:1:0.5.

[0077] Adding solvents such as acetone multiple times can control the viscosity of the system and reduce the concentration of reactants in the system during the reaction. In addition, due to the low boiling point of acetone, it has a strong ability to dissolve polyurethane and is easy to remove. After negative pressure vacuum removal, the obtained product can be substantially free of acetone.

[0078] 4. Silane-treated light-controlled nanomaterials:

[0079] Add light-controlled nanomaterials to a vertical nitrogen-fixing powder dryer with bag dust collection and other devices, heat and stir while spraying a mixed solution formed by KH550, KH560, KH570 coupling agents and other components, the temperature does not exceed 80°C, stir, dry, modify and disperse for about 1 hour, and then discharge the material to a cooling bin for standby use. The light-controlled nanomaterial is titanium oxide, tungsten oxide, cerium oxide, and vanadium oxide mixed in a ratio of 1:2:1:1, and the mass ratio of light-controlled nanomaterials: KH550:KH560:KH570 can be 10:0.01:0.02:0.03.

[0080] Silane-modified nanofillers can provide better integration of inorganic / organic material components in coatings.

[0081] 5. Composite anti-sagging agent thixotropic paste:

[0082] Add appropriate amount of deionized water to the dispersion cylinder, then add appropriate amount of nano calcium, gas silicon, LS wax powder, bentonite while stirring, and high-speed shear dispersion under vacuum-0.1MPa for 2-4h until the scraper fineness test is below 40um, and then fill the barrel and discharge the material. The thixotropic agent obtained after physical mixing is more suitable for the silane-modified polyurethane system of the present invention, which can assist in forming a good three-dimensional network structure, thereby improving the weather resistance and mechanical properties of the coating. The mass ratio of water: nano calcium: gas silicon: bentonite can be 130:200:3:1:1.

[0083] 6. Coating screw preparation

[0084] The water-based silane-modified polyurethane emulsion in step 3, the silane-treated light-controlled nanomaterial in step 4, the filler, the composite anti-sagging agent thixotropic paste in step 5, and a mixture of additives such as a water-retaining agent, a mildew-proof agent, a film-forming aid, a wetting dispersant, and a defoaming agent are accurately measured and put into a twin-screw machine, and the water-based silane-modified polyurethane waterproof coating is obtained by degassing, grinding, dispersing and extruding.

[0085] In general, the coating and preparation method proposed in the present invention mainly graft different silanes onto the polyurethane structure, so that the material has excellent affinity for pigments, fillers and base layers, and has excellent hydrophobicity and water resistance, so that the material has extremely low water absorption, improving the overall performance of the material. In addition, through the chain extension of sulfonates and carboxylic acids in appropriate proportions, the polyurethane can be self-emulsified and obtain excellent water phase dispersion ability. Furthermore, through the optimization of the polyurethane prepolymer reaction process, the overall prepolymer molecular weight distribution of the material is uniform, the viscosity is low, and the physical properties of the product are greatly improved.

[0086] In another aspect of the present disclosure, the present disclosure provides a coating. The coating is formed using the aforementioned water-based polyurethane coating. Thus,

[0087] The methods used in the following examples are conventional methods unless otherwise specified, and the reagents used are commercially available reagents unless otherwise specified. For example, the reagents used in each step can be as follows:

[0088] Light-controlled nanomaterials: one or more nanoscale materials selected from titanium dioxide, cerium oxide, zinc oxide, tungsten oxide, silicon oxide, vanadium oxide, etc., with a particle size preferably of 20-100 nm, which can be purchased from the Institute of Organic Chemistry of the Yangtze River Delta Innovation Center.

[0089] Wetting agent dispersant: select one or more of Dow's 731A dispersant, Wanhua's c30 dispersant, BYK190 dispersant, and Dow's bd-109.

[0090] Coupling agent: one or more of the silane coupling agents WD50, KH550, KH560, KH570, and IPST produced by Hubei Wuda Silicone Company.

[0091] Defoaming agent: P803 silicone defoaming agent, Nopco sn154 defoaming agent, BASF 2410 defoaming agent, Nopco NXZ defoaming agent, etc., any one or more thereof.

[0092] Filler: one or more of the following: heavy calcium 101a, 201a from Jiangsu Qunxin, talc 1000 from Jiangxi Kete, calcium hydrogen 601 from Qingzhou Yuxin, heavy calcium ld200 and ld600 from Suzhou Lida, heavy calcium cc1500 and cc1000 from Guangyuan, talc dhs218, barium sulfate 151 and 051 from Qunxin.

[0093] Isocyanate: any one or more of Wanhua Chemical’s TDI, MDI, HDI and HMDI.

[0094] Polyether polyol: 300, 400, 1000d from Dongda Chemical, any one or more.

[0095] Thixotropic agent: Wacker hydrophilic silica, Changan Renheng's organic bentonite, Zhejiang Jinxiong nano calcium cc601, any one or more.

[0096] Water-retaining agent: one or more of Huiguang 100,000 hydroxymethyl cellulose ether and hydroxyethyl cellulose ether Aqualon 250.

[0097] Antifungal agent: German Shumei DF-19 antifungal agent, New Zealand Concides IP 20 antifungal agent, Troy Tory MICROPEL 5DIDP antibacterial antifungal agent, OPBA and DIDP compound, any one or more.

[0098] Film-forming aid: any one or more of DOW DPM film-forming aid, Eastman film-forming aid TEXANOL, DOW DALPAD 292, and RHODIASOLV DIB odorless film-forming aid.

[0099] Hydrophilic chain extender: sodium ethylenediaminesulfonate, Anhui Zhongen Chemical Co., Ltd.; dimethylolpropionic acid (DMPA), Hubei Changsheng Chemical.

[0100] Chain extender: 1-4 butanediol, diethylene glycol

[0101] Example 1

[0102] This example provides a silane-modified polyurethane coating, whose raw materials include: 40 parts of water-based silane polyurethane emulsion, 1 part of partially hydrolyzed silane gel, 10 parts of silane-treated light-controlled nanomaterials, 0.1 parts of dispersant, 0.2 parts of defoamer, 45.3 parts of filler (50% each of heavy calcium sulfate and barium sulfate), 3 parts of composite anti-sagging thixotropic paste, 0.3 parts of water-retaining agent, and 0.1 parts of mildew inhibitor.

[0103] The preparation method thereof comprises the following steps:

[0104] The water-based silane-modified polyurethane emulsion in step 3, the silane-treated light-controlled nanomaterial in step 4, the filler, the composite anti-sagging agent thixotropic paste in step 5, and a mixture of additives such as a water-retaining agent, a mildew-proof agent, a film-forming aid, a wetting dispersant, and a defoaming agent are accurately measured and put into a twin-screw machine, and the water-based silane-modified polyurethane waterproof coating is obtained by degassing, grinding, dispersing and extruding.

[0105] Example 2

[0106] This example provides a silane-modified polyurethane coating, whose raw materials include: 35 parts of water-based silane polyurethane emulsion, 1 part of partially hydrolyzed silane gel, 10 parts of silane-treated light-controlled nanomaterials, 0.1 parts of dispersant, 0.2 parts of defoamer, 48.3 parts of filler (50% each of heavy calcium sulfate and barium sulfate), 5 parts of composite anti-sagging thixotropic paste, 0.3 parts of water-retaining agent, and 0.1 parts of mildew inhibitor.

[0107] The preparation method thereof comprises the following steps:

[0108] The water-based silane-modified polyurethane emulsion in step 3, the silane-treated light-controlled nanomaterial in step 4, the filler, the composite anti-sagging agent thixotropic paste in step 5, and a mixture of additives such as a water-retaining agent, a mildew-proof agent, a film-forming aid, a wetting dispersant, and a defoaming agent are accurately measured and put into a twin-screw machine, and the water-based silane-modified polyurethane waterproof coating is obtained by degassing, grinding, dispersing and extruding.

[0109] Example 3

[0110] This example provides a silane-modified polyurethane coating, whose raw materials include: 45 parts of water-based silane polyurethane emulsion, 1 part of partially hydrolyzed silane gel, 10 parts of silane-treated light-controlled nanomaterials, 0.1 parts of dispersant, 0.2 parts of defoamer, 40.3 parts of filler (50% each of heavy calcium sulfate and barium sulfate), 3 parts of composite anti-sagging thixotropic paste, 0.3 parts of water-retaining agent, and 0.1 parts of mildew inhibitor.

[0111] The preparation method thereof comprises the following steps:

[0112] The water-based silane-modified polyurethane emulsion in step 3, the silane-treated light-controlled nanomaterial in step 4, the filler, the composite anti-sagging agent thixotropic paste in step 5, and a mixture of additives such as a water-retaining agent, a mildew-proof agent, a film-forming aid, a wetting dispersant, and a defoaming agent are accurately measured and put into a twin-screw machine, and the water-based silane-modified polyurethane waterproof coating is obtained by degassing, grinding, dispersing and extruding.

[0113] Comparative Example 1

[0114] The method is basically the same as Example 1, except that the light-controllable nanomaterial is not added, and the amount of other materials added is adaptively adjusted.

[0115] Comparative Example 2

[0116] The method is basically the same as Example 1, except that the hydrolyzed gel is not added and the amount of other materials added is adjusted adaptively.

[0117] Comparative Example 3

[0118] The method is basically the same as Example 1, except that no silane is added to the silane-modified resin, and the amount of other materials added is adjusted adaptively.

[0119] Performance Testing

[0120] The waterproof coatings prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests, and the specific results are shown in Table 3.

[0121] Table 3

[0122]

[0123]

[0124]

[0125] It can be seen from the above table that the coatings of the embodiments of the present disclosure all have good performance, high weather resistance, and high bonding strength to wet base surfaces.

[0126] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0127] The disclosure above provides many different embodiments or examples to implement different structures of the present disclosure. In order to simplify the present disclosure, the components and settings of specific examples are described above. Of course, they are only examples, and the purpose is not to limit the present disclosure. In addition, the present disclosure can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0128] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of various changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A waterborne polyurethane coating, characterized in that: The raw materials for forming the waterborne polyurethane coating include: Silane modified waterborne polyurethane emulsion; Silane modified UV resistant nanofillers; and additive, The silane-modified waterborne polyurethane emulsion is obtained by reacting a silane-modified composite isocyanate and a polyether polyol. The silane-modified waterborne polyurethane emulsion and the silane-modified anti-UV nanofiller have a silane group, an epoxy group, a vinyl group, and optionally a urea group.

2. The waterborne polyurethane coating according to claim 1, characterized in that: The silane-modified waterborne polyurethane emulsion and the silane-modified UV-resistant nanofiller are obtained by modification with a modifier, wherein the modifier includes a silane coupling agent. The silane coupling agent includes any one or more of WD50, KH550, KH560, KH570 and IPST.

3. The waterborne polyurethane coating according to claim 2, characterized in that: The silane coupling agent includes various coupling agents.

4. The waterborne polyurethane coating according to claim 3, characterized in that: The mass ratio of isocyanate to the silane coupling agent in the raw materials for forming the composite isocyanate is (7-10): (0.8-2).

5. The waterborne polyurethane coating according to claim 1, characterized in that: The raw materials for forming the waterborne polyurethane coating further include hydrolysis coupling gel, and the hydrolysis coupling gel is formed by hydrolysis reaction of multiple silane coupling agents.

6. The waterborne polyurethane coating according to claim 1, characterized in that: The silane-modified anti-UV nanofiller is formed by nanoparticles and a modifier. The nanoparticles include at least one of titanium dioxide, cerium oxide, zinc oxide, tungsten oxide, silicon oxide and vanadium oxide, The modifier includes various silane coupling agents.

7. The waterborne polyurethane coating according to claim 1, characterized in that: The additives include a composite anti-sagging agent thixotropic paste, and optionally at least one of a water retaining agent, a mildew preventer, a film former, a dispersant, a defoaming agent and a filler. The composite anti-sagging agent thixotropic paste comprises nano calcium, gas silicon, wax powder and bentonite.

8. The waterborne polyurethane coating according to claim 1, characterized in that: In the raw materials for forming the silane-modified waterborne polyurethane emulsion, the mass ratio of the complex isocyanate to the polyether polyol is (3-8): (15-30).

9. The waterborne polyurethane coating according to claim 1, characterized in that: Satisfy at least one of the following conditions: The viscosity of the waterborne polyurethane coating is 3500-8400 mPa.s; The solid content of the waterborne polyurethane coating is not less than 75%.

10. A method for preparing the waterborne polyurethane coating according to any one of claims 1 to 9, characterized in that: include: Forming a composite isocyanate, wherein the composite isocyanate is formed by reacting an isocyanate and a modifier containing a silane at a temperature not higher than 20 degrees Celsius; forming a silane-modified waterborne polyurethane emulsion, wherein the silane-modified waterborne polyurethane emulsion is formed by adding a polyether polyol to the composite isocyanate; forming a silane-modified anti-UV nanofiller, wherein the modified anti-UV nanofiller is obtained by treating nanoparticles with the modifier, The silane-modified waterborne polyurethane emulsion, the silane-modified anti-UV nanofiller and the additive are mixed and subjected to a degassing treatment to obtain the waterborne polyurethane coating.

11. The method according to claim 10, characterized in that The method satisfies at least one of the following conditions: When forming the composite isocyanate, the isocyanate and the first modifier are added to cold water and the temperature is maintained at no more than 20 degrees Celsius, and then the second modifier to the fourth modifier are sequentially added dropwise, reacted for 0.5-1.5 hours and the temperature is controlled to be no more than 20 degrees Celsius, and the mass ratio of the isocyanate, the first modifier, the second modifier, the third modifier and the fourth modifier is (8-10): (0.3-0.8): (0.05-0.2): (0.1-0.3): (0.2-0.5); When forming the silane-modified waterborne polyurethane emulsion, the polyether polyol is added dropwise to the composite isocyanate and reacted for 2-4 hours, and a solvent is added at least once during the reaction, wherein the solvent includes acetone; The additive comprises a composite anti-sagging agent thixotropic paste, and the composite anti-sagging agent thixotropic paste is obtained by physically mixing nano calcium, gas silicon, wax powder and bentonite.

12. The method according to claim 10, characterized in that The method further comprises the steps of forming a hydrolyzable coupling agent gel, and mixing the hydrolyzable coupling agent gel with the silane-modified aqueous polyurethane emulsion, the silane-modified anti-UV nanofiller and the additive to perform a degassing treatment. The operation of forming the hydrolyzable coupling agent gel comprises mixing and stirring a plurality of silane coupling agents and water in a closed container to perform a hydrolysis reaction.

13. A coating, characterized in that: The coating is formed using the waterborne polyurethane coating according to any one of claims 1 to 9.

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