Aqueous two-component polyurethane coating composition

Abstract

The invention relates to the field of coating materials, and discloses a water-based two-component polyurethane coating composition which comprises a first component and a second component, the first component comprises silicon modified polyacrylate polyol, and the second component comprises polyisocyanate; the silicon modified polyacrylate polyhydric alcohol comprises polysiloxane modified polyacrylate polyhydric alcohol. Also disclosed is the use of the aqueous two-component polyurethane coating composition for forming a coating with low surface energy and / or high water contact angle on the surface of a substrate. Also disclosed is a coated substrate comprising a substrate and the coating composition applied to at least a portion of the substrate. Further disclosed is an electronic product, at least a portion of a surface of which is coated with the coating composition, or a substrate coated with the coating composition.

Description

Technical Field

[0001] This invention relates to the field of coatings, and more particularly to water-based two-component polyurethane coatings, especially coatings for use on the surfaces of electronic products, such as PC, PC+ABS, ABS, magnesium alloys and aluminum alloys. Background Technology

[0002] Electronic products, such as mobile phones, computers, and televisions, are becoming increasingly indispensable in daily work and life. To achieve both aesthetics and durability, it is necessary to coat and protect the surface of these products.

[0003] Existing coating compositions typically use highly pungent organic solvents as diluents. These solvents, such as xylene and gasoline, are flammable and explosive, posing significant hazards to human health and the environment. The coating, exposed to air on the coated surface, is easily damaged by mechanical abrasion and can corrode due to contact with cosmetics and alcohol. Furthermore, some consumers find the matte finish of electronic products more appealing.

[0004] Therefore, there is a need to develop an environmentally friendly coating product that can simultaneously meet the performance and appearance requirements of electronic product applications. Summary of the Invention

[0005] The inventors have conducted extensive research and developed a water-based two-component polyurethane coating composition that, while meeting environmental protection requirements, also possesses excellent stain resistance, abrasion resistance, scratch resistance, and chemical resistance, as well as superior flexibility, ensuring that it will not crack when folded, and has a smooth feel and controllable gloss.

[0006] This invention provides an aqueous two-component polyurethane coating composition comprising a first component and a second component, wherein the first component comprises a silicone-modified polyacrylate polyol, and the second component comprises a polyisocyanate; the silicone-modified polyacrylate polyol comprises a polysiloxane-modified polyacrylate polyol.

[0007] The present invention also provides the use of the waterborne two-component polyurethane coating composition for forming a coating with low surface energy and / or high water contact angle on a substrate surface.

[0008] The present invention also provides a coated substrate, comprising a substrate and the above-described waterborne two-component polyurethane coating composition coated on at least a portion of the substrate.

[0009] The present invention also provides an electronic product, at least a portion of the surface of which is coated with the above-described waterborne two-component polyurethane coating composition, or includes a substrate coated with the above-described waterborne two-component polyurethane coating composition.

[0010] The features and advantages of the present invention will be specifically presented in the following detailed description of the embodiments. Attached Figure Description

[0011] Figure 1 The results show the antifouling performance test results of the water-based coating composition of the present invention.

[0012] Figure 2 The water contact angle test results were used to compare the composition and the waterborne coating composition of the present invention.

[0013] Figure 3-4 To compare the abrasion resistance test results of the composition and the waterborne coating composition of the present invention.

[0014] Figure 5 To compare the antifouling performance (resistance to easily staining chemicals) test results of the composition and the water-based coating composition of the present invention.

[0015] Figure 6 The results of flexibility tests were used to compare the composition and the waterborne coating composition of the present invention. Detailed Implementation

[0016] As used herein, unless otherwise expressly stated, expressions such as numerical values, ranges, contents, or percentages used in the specification and claims should be considered to vary in all cases according to the term "about," even if the term is not explicitly stated. Therefore, unless stated to the contrary, the numerical parameters listed in the specification and claims herein are approximate values ​​and may vary according to the performance desired by the invention.

[0017] Although the numerical ranges and parameters listed in this invention are approximate, the values ​​listed in the specific embodiments are recorded as accurately as possible. However, any value inherently possesses a certain degree of error. This error is a necessary consequence of the standard deviation derived from the corresponding measurement method.

[0018] Furthermore, it should be understood that any numerical range described herein is intended to include all subranges falling within it. For example, the range “1 to 10” is intended to include all subranges between the minimum value 1 and the maximum value 10, i.e., a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0019] In this application, unless otherwise expressly stated, the use of the singular includes the plural and the plural includes the singular. Furthermore, in this application, unless otherwise expressly stated, "or" is used to mean "and / or," even if "and / or" may be explicitly used in certain circumstances. Additionally, in this application, unless otherwise expressly stated, "a" or "an" is used to mean "at least one." For example, "a" polymer, "a" coating, etc., refer to any one or more of these items. And, as those skilled in the art will recognize, features of one embodiment may be used in conjunction with other embodiments, even if not explicitly stated.

[0020] As used herein, "coating composition" refers to a substance that, when applied to the surface of a substrate, can be cured by natural or artificial methods to form a coating film covering the surface of the substrate, providing protective and decorative functions.

[0021] As used herein, “water-based” means that the solvent of the coating composition contains at least 50 wt% water based on the total solvent weight of the coating composition.

[0022] As used herein, a "two-component" coating composition refers to components that are reactive with each other (i.e., the first component and the second component) that are stored separately prior to application to avoid premature reaction. Typically, the first and second components may be mixed together some time before application.

[0023] The waterborne two-component coating composition according to the present invention has a low VOC content. As used herein, the term "VOC (volatile organic compound)" refers to any organic compound with a boiling point less than or equal to 250°C (482°F) measured at a standard atmospheric pressure of 101.3 kPa. Organic solvents are generally the primary source of VOCs. The VOC content (excluding water) of the waterborne two-component coating according to the present invention can be up to about 300 g / L, such as 50-300 g / L. The VOC value can be obtained by detecting the content of each organic compound component in the formulation using gas chromatography and then summing the contents of each component.

[0024] The waterborne two-component polyurethane coating composition according to the present invention is a thermosetting coating composition, meaning that the coating composition requires heating and curing to form a film after being applied to the surface of a substrate. Hereinafter, the term "curing" refers to the process by which a material becomes fixed and no longer flows. Suitably, the two-component coating composition according to the present invention can be cured within 2 to 8 hours under baking conditions of 55-110°C. For example, the two-component coating composition according to the present invention can be fully cured within 6 hours at 80°C. Hereinafter, "fully cured" means that the cured film layer can have a MEK double rub value of at least 50 times.

[0025] The present invention provides an aqueous two-component polyurethane coating composition comprising a first component and a second component, wherein the first component comprises a silicone-modified polyacrylate polyol, and the second component comprises a polyisocyanate; the silicone-modified polyacrylate polyol comprises a polysiloxane-modified polyacrylate polyol.

[0026] The silicone-modified polyacrylate polyol used in the waterborne two-component polyurethane coating composition according to the present invention refers to a silicone-modified polymer with (meth)acrylic monomers as its basic component. The term "polyol" refers to a compound having two or more hydroxyl (-OH) groups. The term "silicone-modified" means that the polymer contains one or more silicon units. The term "basic component" refers to the silicone-modified polyacrylate polyol in which (meth)acrylic monomers account for at least about 70 wt% of all polymeric monomers, for example, at least about 80 wt%, such as at least about 90 wt%.

[0027] The silicone-modified polyacrylate polyol used in this invention has a suitably high hydroxyl value. Suitablely, the silicone-modified polyacrylate polyol may have a hydroxyl value greater than 50 mgKOH / g, and suitably, the hydroxyl value is 50-150 mgKOH / g, for example, 60, 70, 80, 90, 100, 110, 120, 130, or 140 mgKOH / g. Suitablely, the hydroxyl value of the silicone-modified polyacrylate polyol may be 50 mgKOH / g or higher, 60 mgKOH / g or higher, 70 mgKOH / g or higher, 80 mgKOH / g or higher, 90 mgKOH / g or higher, or 100 mgKOH / g or higher, and / or, 150 mgKOH / g or lower, 140 mgKOH / g or lower, 130 mgKOH / g or lower, 120 mgKOH / g or lower, or 110 mgKOH / g or lower. The hydroxyl value refers to the number of milligrams of potassium hydroxide (KOH) equivalent to 1 gram of hydroxyl groups in the resin. The hydroxyl value can be determined with reference to the ASTM D4274-16 standard.

[0028] The silicone-modified polyacrylate polyols used in this invention have suitable molecular weights. Suitably, the silicone-modified polyacrylate polyols may have a weight-average molecular weight (Mw) of 3000-12000, such as 4000, 5000, 6000, 7000, 8000, 9000, 10000, or 12000 Mw. Suitably, the weight-average molecular weight (Mw) of the silicone-modified polyacrylate polyols may be 3000 or higher, 4000 or higher, 5000 or higher, 6000 or higher, or 7000 or higher, and / or 12000 or lower, 10000 or lower, 9000 or lower, or 8000 or lower. The weight-average molecular weight (Mw) can be determined by gel permeation chromatography using suitable standards such as polystyrene standards, and the unit is g / mol.

[0029] The silicone-modified polyacrylate polyols used in this invention have suitable glass transition temperatures. Suitably, the silicone-modified polyacrylate polyols can have glass transition temperatures from 40 to 90°C, such as 50°C, 60°C, 70°C, or 80°C. For example, the glass transition temperature of the silicone-modified polyacrylate polyols can be 40°C or higher, 50°C or higher, or 60°C or higher, and / or 90°C or lower, 80°C or lower, or 70°C or lower. The glass transition temperature can be measured by dynamic thermomechanical analysis (DMA) using a TA Instruments Q800 instrument with the following parameters: frequency of 10 Hz, amplitude of 5 mm, and temperature ramp from -100°C to 250°C. According to ASTM D7028, the glass transition temperature is determined as the peak value of the tanδ curve.

[0030] Suitably, the silicon-modified polyacrylate polyol may include a polysiloxane-modified polyacrylate polyol. The polysiloxane comprises repeating silicon-oxygen-silicon units and includes silane-alkyl and / or silane-alkoxy groups. Suitably, the polysiloxane-modified polyacrylate polyol may include a polysiloxane containing a single-terminal unsaturated double bond, i.e., a polysiloxane containing an olefin double bond at one end. For example, a polysiloxane containing a single-terminal unsaturated double bond can be free-radically polymerized with a (meth)acrylic acid monomer, thereby covalently grafting the polysiloxane onto the polyacrylate polyol.

[0031] The silicon content of the silicon-modified polyacrylate polyols suitable for use in this invention can be 0-30 wt%, suitably 5-20 wt%, more preferably 5 wt%-15 wt%, such as 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, or 14 wt%. Suitably, the silicon content of the silicon-modified polyacrylate polyols can be 5 wt% or higher, 6 wt% or higher, 7 wt% or higher, 8 wt% or higher, 9 wt% or higher, or 10 wt% or higher, and / or 15 wt% or lower, 14 wt% or lower, 13 wt% or lower, 12 wt% or lower, or 11 wt% or lower. The silicon content refers to the weight percentage of silicon (e.g., a polysiloxane containing a single-terminal unsaturated double bond) to the solid weight of the silicon-modified polyacrylate polyol resin.

[0032] Suitably, the silicone-modified polyacrylate polyol can be premixed with an appropriate amount of matting agent to obtain a matte silicone-modified polyacrylate polyol before being added to the coating composition. The amount of matting agent can be adjusted according to the desired gloss. For example, in the matte silicone-modified polyacrylate polyol, the solid weight ratio of the silicone-modified polyacrylate polyol to the matting agent can be at least 80:20, such as 90:10. Correspondingly, the silicone-modified polyacrylate polyol not premixed with the matting agent can be referred to as a high-gloss silicone-modified polyacrylate polyol. Suitably, the matting agent can include amorphous silica. Suitably, the matting agent can include amorphous silica having a particle size of 1 to 10 μm, such as amorphous silica with a particle size of 1 to 6 μm. The particle size of the matting agent can be determined by a laser particle size analyzer (ISO 13320-1).

[0033] The waterborne two-component polyurethane coating composition according to the present invention can use a combination of matte and high-gloss silicone-modified polyacrylate polyols in any weight ratio, for example, 0-100:100-0, the ratio range of which can be adjusted according to the gloss requirements of the actual application. Suitablely, the weight ratio of matte silicone-modified polyacrylate polyol to high-gloss silicone-modified polyacrylate polyol in the present invention is 60:40-100:0, suitablely, 85:15. Based on the total weight of the coating composition, matting agent can be present in an amount of 4-10 wt%. For example, the present invention can use a certain proportion of matte silicone-modified polyacrylate polyol and high-gloss silicone-modified polyacrylate polyol to form a coating with a gloss of less than 10 GU at a 60-degree angle, suitablely, with a gloss of 2-7 GU at a 60-degree angle.

[0034] Based on the total solids weight of the waterborne coating composition, the coating composition according to the present invention may comprise about 30 wt% or more, such as about 40 wt% or more, for example about 50 wt% or more, of silicone-modified polyacrylate polyol, and / or may comprise about 90 wt% or less, such as about 80 wt% or less, for example about 70 wt% or less, of silicone-modified polyacrylate polyol. Based on the total solids weight of the waterborne coating composition, the silicone-modified polyacrylate polyol may be present in the range of about 30-90 wt%, such as about 40-80 wt%, for example about 50-70 wt%, or any other combination of these extreme values. In this document, "total solids weight of the waterborne coating composition" refers to the total weight remaining after the solvent in the waterborne coating composition has evaporated.

[0035] The first component of the waterborne coating composition according to the present invention further includes a silicone-modified polyurethane resin. The polyurethane resin refers to a polymer whose repeating units include urethane groups. The polyurethane may comprise a polymer of at least 50 wt% organic units, such as at least 70 wt%, or at least 90 wt% organic units, linked by urethane bonds. In this document, the organic units comprise one or more residues selected from simple diols, such as butanediol, polyester diol, polyether diol, polycarbonate diol, etc.

[0036] The silicon-modified polyurethane used in this invention may include a polysiloxane-modified polyurethane. The polysiloxane comprises repeating silicon-oxygen-silicon units and includes silane-alkyl and / or silane-alkoxy groups. Suitably, the polysiloxane-modified polyurethane comprises a polysiloxane containing a single-terminal unsaturated double bond, i.e., a polysiloxane containing an alkene double bond at one end. The silicon content of the silicon-modified polyurethane suitable for this invention may be 0-30 wt%, suitably 5-20 wt%, such as 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, or 19 wt%. Suitably, the silicon content of the silicon-modified polyurethane may be 5 wt% or higher, 6 wt% or higher, 7 wt% or higher, 8 wt% or higher, 9 wt% or higher, 10 wt% or higher, 11 wt% or higher, 12 wt% or higher, 13 wt% or higher, or 14 wt% or higher, and / or, 20 wt% or lower, 19 wt% or lower, 18 wt% or lower, 17 wt% or lower, 16 wt% or lower, or 15 wt% or lower. The silicon content refers to the weight percentage of silicon (e.g., a polysiloxane containing a single-terminal unsaturated double bond) to the solid weight of the silicon-modified polyurethane.

[0037] The silicone-modified polyurethane used in this invention can have a suitable molecular weight. Suitably, the silicone-modified polyurethane can have a weight-average molecular weight (Mw) of 3000-12000, such as 4000, 5000, 6000, 7000, 8000, 9000, 10000, or 11000 Mw. Suitably, the weight-average molecular weight (Mw) of the silicone-modified polyurethane can be 3000 or higher, 4000 or higher, 5000 or higher, 6000 or higher, or 7000 or higher, and / or 12000 or lower, 11000 or lower, 10000 or lower, 9000 or lower, or 8000 or lower. The weight-average molecular weight (Mw) can be determined by gel permeation chromatography using a suitable standard, such as a polystyrene standard, and the unit is g / mol.

[0038] The silicone-modified polyurethane used in this invention can have a suitable hydroxyl value. The hydroxyl value of the silicone-modified polyurethane can be less than 40 mgKOH / g. For example, the hydroxyl value of the silicone-modified polyurethane can be 35 mgKOH / g or less, 30 mgKOH / g or less, 20 mgKOH / g or less, or 10 mgKOH / g or less. The hydroxyl value refers to the number of milligrams of potassium hydroxide (KOH) equivalent to the hydroxyl groups in 1 gram of resin. The hydroxyl value can be determined with reference to ASTM D4274-16 standard.

[0039] The silicone-modified polyurethane used in this invention can have a suitable glass transition temperature. Suitably, the glass transition temperature of the silicone-modified polyurethane can be from -60 to -10°C. For example, the glass transition temperature of the silicone-modified polyurethane can be -60°C or higher, -50°C or higher, or -40°C or higher, and / or -10°C or lower, -20°C or lower, or -30°C or lower. The glass transition temperature can be measured by dynamic thermomechanical analysis (DMA) using a TA Instruments Q800 instrument with the following parameters: frequency of 10 Hz, amplitude of 5 mm, and temperature ramp from -100°C to 250°C. According to ASTM D7028, the glass transition temperature is determined as the peak value of the tanδ curve.

[0040] Based on the total solids weight of the waterborne coating composition, the coating composition according to the present invention may include about 0.01 wt% or more, such as about 0.1 wt% or more, for example about 0.5 wt% or more of silicone-modified polyurethane, and / or may include about 50 wt% or less, such as about 45 wt% or less, for example about 40 wt% or less of silicone-modified polyurethane. Based on the total solids weight of the waterborne coating composition, the silicone-modified polyurethane may be present in the range of about 0.01 to 50 wt%, such as about 0.1 to 45 wt%, for example about 0.5 to 40 wt%, or any other combination of these extreme values. In this document, "total solids weight of the waterborne coating composition" refers to the total weight remaining after the solvent in the waterborne coating composition has evaporated.

[0041] The second component of the waterborne coating composition according to the present invention comprises a polyisocyanate.

[0042] The polyisocyanates used in this invention may include HDI-type polyisocyanates and / or IPDI-type polyisocyanates. Suitably, the polyisocyanates may include at least 10 wt% of HDI-type polyisocyanates based on the total solid weight of the polyisocyanates, such as 20 wt% or more of HDI-type polyisocyanates.

[0043] Based on the total solids weight of the waterborne coating composition, the coating composition according to the present invention may include about 10 wt% or more, such as about 15 wt% or more, for example about 20 wt% or more of polyisocyanate, and / or may include about 50 wt% or less, such as about 40 wt% or less, for example about 30 wt% or less of polyisocyanate. Based on the total solids weight of the waterborne coating composition, the polyisocyanate may be present in a range of about 10 to 50 wt%, such as about 15 to 40 wt%, for example about 10 to 30 wt%, or any other combination of these extreme values. In this document, "total solids weight of the waterborne coating composition" refers to the total weight remaining after the solvent in the waterborne coating composition has evaporated.

[0044] In the waterborne two-component coating composition according to the present invention, a specific resin combination and a balanced dosage provide the coating composition with excellent appearance and mechanical properties. Suitably, the weight ratio of the silicone-modified polyacrylate polyol to the silicone-modified polyurethane to the polyisocyanate can be (8-40): (1-20): (10-25). For example, the weight ratio of the silicone-modified polyacrylate polyol to the silicone-modified polyurethane to the polyisocyanate can be (13-30): (1-10): (10-25). For example, the weight ratio of the silicone-modified polyacrylate polyol to the silicone-modified polyurethane to the polyisocyanate can be (8-22): (6-18): (10-25).

[0045] The waterborne coating compositions of the present invention may also contain other optional ingredients that will not adversely affect the coating composition or the resulting coating. Such optional ingredients are typically included in the coating composition to enhance the aesthetics of the coating; facilitate the manufacture, processing, treatment, and application of the composition; and further improve the specific functional properties of the coating composition or the resulting cured coating. These optional ingredients include, but are not limited to, rheology modifiers for adjusting the rheological properties of the coating, improving resistance to settling during storage and resistance to sag during application; defoamers and antifoaming agents for inhibiting bubble formation during production and for escaping or breaking existing bubbles; anti-pinhole agents for increasing the surface tension of the coating and eliminating pinholes; fragrances for providing a pleasant odor to the coating; preservatives for protecting the coating from mold; pH adjusters for controlling and stabilizing the pH of the coating; waxes for improving scratch resistance and tactile feel; thickeners for increasing coating viscosity and improving wet film thickness and protecting the coating from settling and stratification, etc. Each optional ingredient is preferably included in an amount sufficient to achieve its intended purpose, but not in an amount that adversely affects the coating composition or the resulting coating.

[0046] The aqueous coating composition according to the invention optionally includes a wetting agent. Suitable wetting agents for use in the invention may include one or more of silicone surfactants.

[0047] Based on the total weight of the waterborne coating composition, the waterborne coating composition according to the present invention may include about 0.01 wt% or more, 0.1 wt% or more, or 0.5 wt% or more of a wetting agent, and / or may include about 10 wt% or less, such as about 5 wt% or less, for example about 3 wt% or less of a wetting agent. Based on the total weight of the waterborne coating composition, the wetting agent may be present in a range of about 0.01 to 10 wt%, such as about 0.1 to 5 wt%, for example about 0.5 to 3 wt%, or any other combination of these endpoints.

[0048] For example, the waterborne coating composition according to the invention may optionally include a defoamer. Suitable defoamers for use in the invention may include one or more silicone defoamers.

[0049] Based on the total weight of the waterborne coating composition, the waterborne coating composition according to the present invention may include about 0.01 wt% or more, 0.1 wt% or more, or 0.5 wt% or more of a defoamer, and / or may include about 10 wt% or less, such as about 5 wt% or less, for example about 3 wt% or less of a defoamer. Based on the total weight of the waterborne coating composition, the defoamer may be present in a range of about 0.01 to 10 wt%, such as about 0.1 to 5 wt%, for example about 0.5 to 3 wt%, or any other combination of these extreme values.

[0050] For example, the aqueous coating composition according to the invention may optionally include a thixotropic agent. Suitable thixotropic agents for use in the invention may include one or more polyurethane associative thixotropic agents.

[0051] Based on the total weight of the waterborne coating composition, the waterborne coating composition according to the present invention may include about 0.01 wt% or more, 0.1 wt% or more, or 0.5 wt% or more of a thixotropic agent, and / or may include about 10 wt% or less, such as about 5 wt% or less, for example about 3 wt% or less of a thixotropic agent. Based on the total weight of the waterborne coating composition, the thixotropic agent may be present in a range of about 0.01 to 10 wt%, such as about 0.1 to 5 wt%, for example about 0.5 to 3 wt%, or any other combination of these end values.

[0052] For example, the waterborne coating composition according to the invention may optionally include feel and anti-fouling additives. Suitable feel and anti-fouling additives for use in the invention may include one or more polysiloxane-type additives.

[0053] Based on the total weight of the waterborne coating composition, the waterborne coating composition according to the present invention may include about 0.1 wt% or more, 0.5 wt% or more, or 1 wt% or more of a feel and antifouling additive, and / or may include about 10 wt% or less, such as about 5 wt% or less, for example about 3 wt% or less of a feel and antifouling additive. Based on the total weight of the waterborne coating composition, the feel and antifouling additive may be present in a range of about 0.1 to 10 wt%, such as about 0.5 to 5 wt%, for example about 1 to 3 wt%, or any other combination of these end values.

[0054] The aqueous coating composition according to the invention further includes a solvent. Suitable solvents for use in the invention may include water and optional organic solvents, such as alcohol ether solvents.

[0055] Based on the total weight of the waterborne coating composition, the waterborne coating composition according to the present invention may include about 50 wt% or more, 55 wt% or more, or 60 wt% or more of solvent, and / or may include about 75 wt% or less, such as about 70 wt% or less, for example about 65 wt% or less of solvent. Based on the total weight of the waterborne coating composition, the solvent may be present in a range of about 50-75 wt%, such as about 55-70 wt%, for example about 60-65 wt%, or any other combination of these end values.

[0056] The waterborne coating composition provided according to the present invention has a certain silicon content. Suitably, the waterborne coating composition may contain 5-40 wt% silicon based on the total solid weight of the waterborne coating composition, suitably containing 8-20 wt% silicon. For example, the waterborne coating composition contains 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, or 19 wt% silicon. Suitably, the waterborne coating composition contains 9 wt% or higher, 10 wt% or higher, 11 wt% or higher, 12 wt% or higher, 13 wt% or higher, 14 wt% or higher, or 15 wt% or higher, and / or 20 wt% or lower, 19 wt% or lower, 18 wt% or lower, 17 wt% or lower, or 16 wt% or lower silicon. In this document, "total solid weight of the waterborne coating composition" refers to the total weight remaining after the solvent in the waterborne coating composition has evaporated. The silicon content refers to the weight percentage of silicon (e.g., polysiloxanes containing single-terminal unsaturated double bonds) in the total solid weight of the waterborne coating composition.

[0057] According to the waterborne coating composition provided by the present invention, the first component and the second component form a network structure comprising polysiloxanes. This polysiloxane network structure results in a coating with low surface energy, achieving a lotus effect. Suitably, the coating formed by the waterborne coating composition provided by the present invention can have a surface energy of no more than 30 J / m². 2 The surface energy and / or a water contact angle of at least 95°, or even 100°. The surface energy and water contact angle can be determined using a commercially available water contact angle tester, with reference to ASTM D7490-2013.

[0058] According to the waterborne coating composition provided by the present invention, the molar ratio of NCO groups in the second component to OH groups in the first component can be from 0.8:1 to 2.0:1, suitably from 1.1:1 to 1.8:1. For example, the molar ratio of NCO groups in the second component to OH groups in the first component can be 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1 or 1.9:1. Suitablely, the molar ratio of NCO groups in the second component to OH groups in the first component may be 0.9:1 or higher, 1:1 or higher, 1.1:1 or higher, 1.2:1 or higher, 1.3:1 or higher, or 1.4:1 or higher, and / or 1.9:1 or lower, 1.8:1 or lower, 1.7:1 or lower, 1.6:1 or lower, or 1.5:1 or lower.

[0059] The present invention also provides an aqueous two-component polyurethane coating composition comprising a first component and a second component, wherein, by weight,

[0060] The first component includes the following ingredients:

[0061] 40-110 parts of a dispersion of silicone-modified acrylate polyol (solid content 41%-54%);

[0062] 0.1-1 part wetting agent;

[0063] 0.1-1 part defoamer;

[0064] 0-1 part thixotropic agent;

[0065] 0-9 parts organic solvent;

[0066] 0.1-3 parts of hand feel and stain-resistant additives;

[0067] 0.5-10 parts of silicone-modified polyurethane;

[0068] 2-5 parts deionized water;

[0069] The second component includes the following ingredients:

[0070] 15-25 parts polyisocyanate.

[0071] In one specific embodiment, the aforementioned 40-110 parts of the silicone-modified acrylate polyol dispersion comprises 40-80 parts of a matte silicone-modified acrylate polyol dispersion and 0-30 parts of a glossy silicone-modified acrylate polyol dispersion.

[0072] The present invention also provides an aqueous two-component polyurethane coating composition, comprising a first component and a second component, wherein, by weight,

[0073] The first component includes the following ingredients:

[0074] 20-40 parts of a dispersion of siloxane-modified acrylate polyol (solid content 41%-54%);

[0075] 0.1-1 part wetting agent;

[0076] 0.1-1 part defoamer;

[0077] 0-1 part thixotropic agent;

[0078] 0-9 parts organic solvent;

[0079] 0.1-3 parts of hand feel and stain-resistant additives;

[0080] 20-40 parts of a dispersion of siloxane-modified polyurethane (solid content 30%-45%);

[0081] 2-5 parts deionized water;

[0082] The second component includes the following ingredients:

[0083] 15-25 parts polyisocyanate.

[0084] In one specific embodiment, the above-mentioned 20-40 parts of siloxane-modified acrylate polyol dispersion comprises 20-40 parts of matte siloxane-modified acrylate polyol dispersion and 0-10 parts of glossy siloxane-modified acrylate polyol dispersion.

[0085] The water-based coating composition of the present invention can be applied to a substrate before or after forming an article from the substrate. After the coating composition is applied to the substrate, it can be cured using various methods, including, for example, any other method that provides an elevated temperature suitable for curing the coating. The curing process can be carried out in discrete or combined steps. Curing conditions will vary depending on the coating method and the end use. The curing process can be carried out at any suitable temperature; suitably, the coating composition of the present invention can be cured within 2 to 8 hours at 55-110°C. For example, the coating composition of the present invention can be cured within 6 hours at 80°C.

[0086] Based on aesthetic requirements, the waterborne coating composition according to the present invention can achieve the desired gloss by adjusting the amounts of each component, for example, by adjusting the ratio of matte silicone-modified polyacrylate polyol to high-gloss silicone-modified polyacrylate polyol. Suitably, the coating formed by the waterborne coating composition according to the present invention has a gloss of less than 10 GU at a 60-degree angle, suitably, a gloss of 2-7 GU at a 60-degree angle, said gloss being determined according to ASTM D523. Furthermore, the waterborne coating composition according to the present invention exhibits excellent gloss stability, with minimal gloss variation under different mixing speeds and baking times. For example, at mixing speeds of 400-1000 rpm and baking times of 10 minutes to 8 hours, the gloss variation is minimal, for example, less than 0.5 GU. This minimal gloss variation indicates rapid curing of the coating composition in the early stages of film formation.

[0087] The waterborne coating composition according to the present invention can be obtained by the following preparation method, comprising:

[0088] 1) Mix the resin components, solvent, and optional additives at 10~35°C and 500~1500 rpm;

[0089] 2) Mix the polyisocyanate component and optional additives at 10~35℃ and 500~1500 rpm;

[0090] 3) Store the mixtures obtained in steps 1) and 2) separately for later use.

[0091] The present invention also provides the use of the aforementioned waterborne two-component polyurethane coating composition for forming a coating with low surface energy and / or high water contact angle on a substrate surface. The low surface energy refers to the formed coating having a surface energy not exceeding 30 J / m². 2 The surface energy. The high water contact angle refers to a water contact angle of at least 95°, or even 100°, formed on the coating. The surface energy and water contact angle can be determined using a commercially available water droplet angle tester, referring to ASTM D7490-2013.

[0092] Coatings possessing the aforementioned properties (i.e., low surface energy and high water contact angle) exhibit excellent stain resistance, abrasion resistance, scratch resistance, chemical resistance, and / or flexibility. Therefore, the present invention also provides the use of the aforementioned waterborne two-component polyurethane coating composition for forming a coating on a substrate surface to provide stain resistance, abrasion resistance, scratch resistance, chemical resistance, and / or flexibility.

[0093] The present invention also provides a coated substrate comprising a substrate and the above-described aqueous two-component polyurethane coating composition coated on at least a portion of the substrate.

[0094] Suitablely, the substrate may be a metallic substrate, such as a magnesium substrate, an aluminum substrate, such as a magnesium alloy, an aluminum alloy, or a non-metallic substrate, including PC (polycarbonate), PC+ABS, ABS (acrylonitrile-butadiene-styrene), and TPU (thermoplastic polyurethane).

[0095] Suitably, the substrate may be treated / not treated with surfactants, chemicals, flame, UV, and / or plasma. Suitably, the substrate may be coated / not coated with other coatings. For example, when the substrate is metallic, it may be primed. For example, when the substrate is non-metallic, it may be uncoated.

[0096] The present invention also provides an electronic product, at least a portion of the surface of which is coated with the above-described waterborne two-component polyurethane coating composition, or includes a substrate coated with the above-described waterborne two-component polyurethane coating composition.

[0097] Suitablely, the electronic product may be a mobile phone, computer, television, headphones, mouse, etc. Suitablely, the substrate may be a subset of the following: mobile phone, computer, television, headphones, mouse, etc.

[0098] The waterborne two-component polyurethane coating composition of the present invention can be applied by any standard method known in the art, such as spraying, dipping, roller coating, brushing, etc., and then cured under heat to form a coating. Typically, the waterborne two-component polyurethane coating composition according to the present invention can be cured at 55-110°C for 2-8 hours. The coating formed by the coating composition of the present invention can be applied to a thickness of 1-100 μm, suitably 10-50 μm, 10-30 μm, or 10-20 μm.

[0099] Example

[0100] The following embodiments further illustrate the invention, but should not be construed as limiting the invention to the details described in the embodiments. Unless otherwise stated, all parts and percentages in the following embodiments are by weight.

[0101] Examples 1-3 and Comparative Example 1, based on the components and amounts listed in Table 1 below, prepared the waterborne two-component polyurethane coating compositions according to the present invention as follows:

[0102] 1) Add matte silicone-modified acrylate polyol to a container, set the stirring speed to 800~1500 rpm, and then add high-gloss silicone-modified acrylate polyol, silicone-modified polyurethane, wetting agent, defoamer, thixotropic agent, organic solvent, hand feel and antifouling additives and deionized water in sequence while stirring, and keep stirring for 30 minutes.

[0103] 2) Set the stirring speed to 800~1500 rpm, add the isocyanate to the mixture in step 1) while stirring, and keep stirring for 5~20 minutes.

[0104] Table 1. Aqueous two-component coating compositions of Examples 1-3 and Comparative Example 1

[0105]

[0106] a. A dispersion containing silicone-modified acrylate polyol and matting agent (NIPSIL E-1011 from TOSOH), with a solid content of 41-47%, the solid weight ratio of silicone-modified acrylate polyol and matting agent being 90:10, wherein the silicone-modified acrylate polyol is a polysiloxane-modified polyacrylate polyol, which includes polysiloxanes containing single-terminal unsaturated double bonds, with a silicon content of 5-20 wt%, and the silicone-modified acrylate polyol having a hydroxyl value greater than 50 mgKOH / g, a glass transition temperature of 40 to 90 °C, and 3000-12000 Mw;

[0107] b. A dispersion containing silicone-modified acrylate polyols, with a solid content of 41-47%, wherein the silicone-modified acrylate polyols are polysiloxane-modified polyacrylate polyols, which include polysiloxanes containing single-terminal unsaturated double bonds, with a silicone content of 5-20 wt%, and the silicone-modified acrylate polyols have a hydroxyl value greater than 50 mgKOH / g, a glass transition temperature of 40 to 90℃, and a temperature of 3000-12000 Mw;

[0108] c. Including DAOTAN TW 7010 / 36WA from Allnex and NIPSIL E-1011 from TOSOH, with a solid weight ratio of 90:10;

[0109] d. DAOTAN TW 7010 / 36WA from Allnex;

[0110] e. Polysiloxane-modified polyurethane, including polysiloxanes containing single-terminal unsaturated double bonds, with a silicon content of 5-30 wt%, a Mw of 3000-12000, a hydroxyl value of less than 40 mgKOH / g, and a glass transition temperature of -60 to -10 °C.

[0111] f. TEGO TWIN 4100 from EVONIK;

[0112] g. BYK-024 from BYK;

[0113] h. RHEOLATE 299 from ELEMENTIS;

[0114] i. PROPYLENE GLYCOL from BASF;

[0115] j. TEGO GLIDE 410 from EVONIK;

[0116] k. HDI type polyisocyanates and optional IPDI type polyisocyanates.

[0117] The aqueous two-component polyurethane coating compositions of Examples 4-6 and Comparative Example 2 were prepared according to the components and amounts listed in Table 2 below, as detailed below:

[0118] 1) Add matte silicone-modified acrylate polyol to a container, set the stirring speed to 800~1500 rpm, and then add high-gloss silicone-modified acrylate polyol, silicone-modified polyurethane, wetting agent, defoamer, thixotropic agent, organic solvent, hand feel and antifouling additives and deionized water in sequence while stirring, and keep stirring for 30 minutes.

[0119] 2) Set the stirring speed to 800~1500 rpm, and add the isocyanate to the mixture in step 1) while stirring, and keep stirring for 5~20 minutes.

[0120] Table 2. Aqueous two-component coating compositions of Examples 4-6 and Comparative Example 2

[0121]

[0122] a. A dispersion containing siloxane-modified acrylate polyol and matting agent (NIPSIL E-1011 from TOSOH), with a solid content of 48-54%, the solid weight ratio of siloxane-modified acrylate polyol and matting agent being 90:10, wherein the siloxane-modified acrylate polyol is a polysiloxane-modified polyacrylate polyol, which includes polysiloxanes containing single-terminal unsaturated double bonds, and its silicon content is 5-20 wt%. The siloxane-modified acrylate polyol has a hydroxyl value greater than 50 mgKOH / g, a glass transition temperature of 40 to 90 °C, and a wattage of 3000-12000 Mw.

[0123] b. A dispersion containing siloxane-modified acrylate polyols, with a solid content of 41-47%, wherein the siloxane-modified acrylate polyols are polysiloxane-modified polyacrylate polyols, which include polysiloxanes containing single-terminal unsaturated double bonds, with a silicon content of 5-20 wt%, and the siloxane-modified acrylate polyols have a hydroxyl value greater than 50 mgKOH / g, a glass transition temperature of 40 to 90℃, and a wattage of 3000-12000 Mw;

[0124] c. Including DAOTAN TW 7010 / 36WA from Allnex and NIPSIL E-1011 from TOSOH, with a solid weight ratio of 90:10;

[0125] d. DAOTAN TW 7010 / 36WA from Allnex;

[0126] e. A dispersion of polysiloxane-modified polyurethane with a solid content of 30-45%, including polysiloxanes containing single-terminal unsaturated double bonds, a silicon content of 5-30 wt%, a Mw of 3000-12000, a hydroxyl value of less than 40 mgKOH / g, and a glass transition temperature of -60 to -10℃.

[0127] f. TEGO TWIN 4100 from EVONIK;

[0128] g. BYK-024 from BYK;

[0129] h. RHEOLATE 299 from ELEMENTIS;

[0130] i. PROPYLENE GLYCOL from BASF;

[0131] j. TEGO GLIDE 410 from EVONIK;

[0132] k. HDI type polyisocyanates and optional IPDI type polyisocyanates.

[0133] Performance testing

[0134] The coating compositions of Examples 1-6 and Comparative Examples 1-2 were respectively coated onto a substrate, which was a non-metallic substrate that had not been coated with any other coating; then, the substrate containing the above coating compositions was placed under baking conditions for curing. The cured coatings were subjected to the following performance tests.

[0135] Adhesion test

[0136] Test standard: ASTM D3359-02

[0137] Instruments: Cross-cutting tool, cross-cutting device, tape, microscope

[0138] Results: Grade 5B was achieved on PC, PC+ABS, and ABS substrates.

[0139] Conclusion: The coating compositions of Examples 1-6 have good adhesion to PC, PC+ABS and ABS.

[0140] Surface energy / droplet angle

[0141] Tests were conducted using Examples 1, 4, and Comparative Example 2 as examples.

[0142] Test standard: ASTM D7490-2013

[0143] Testing instrument: Water droplet angle tester

[0144] Result: Surface energy <23 J / m 2 Water droplet angle > 104°

[0145] Conclusion: Figure 2 As shown ( Figure 2 a, Figure 2 b and Figure 2 c corresponds to Example 1, Example 4 and Comparative Example 2 respectively), and the coating composition of the present invention has low surface tension.

[0146] Stain resistance / chemical resistance test

[0147] Example 1 ( Figure 1 For example, we will conduct a test.

[0148] Test method: Apply chemicals to the coating surface and then place it in a specific environment (high temperature and high humidity conditions 65℃, 90% RH). After 7 days, wipe the surface with a cloth and visually observe the traces / apply color difference test to observe the color difference.

[0149] Result: As Figure 1 As shown in Figure a, after the chemicals are applied to the coating surface, a lotus leaf effect is formed; such as Figure 1 b and Figure 1 As shown in c, use dry paper towels ( Figure 1 Part 2 of b) or 70% isopropanol ( Figure 1 After wiping the second part of c), the chemicals on the coating surface can be completely wiped clean.

[0150] Conclusion: The coating composition of the present invention has excellent stain resistance and chemical resistance.

[0151] Abrasion resistance test:

[0152] The tests were conducted using Example 1 and Comparative Example 1 as examples.

[0153] Crock Meter Friction Testing Machine

[0154] Test standard: ASTM D6279

[0155] Testing instruments: Taber Linear Abraser 5700 / Taber Linear Abraser 5900, with the fabric used for rubbing being Taber P / N 134567 Crocking Cloth Trimmed to 100 mm * 25 mm Rectangle, and the matching test head being Taber P / N 135681 Rubbing Adapter. The gloss meter was BYK MODEL4520.

[0156] Test method: 500 g load, 50.8 mm stroke, 60 revolutions / minute speed. Rub the coating surface with a fabric (Taber P / N134567 Crocking Cloth) for 15,000 revolutions. Observe the change in gloss of the coating after rubbing to determine the grade. A change in gloss of less than 20% is considered to pass the test.

[0157] Test results are as follows Figure 3 As shown:

[0158] Figure 3 In the figure, 'a' represents the coating prepared by Comparative Example 1. After Crock-meter testing, the gloss change was 220%, and the coating at the friction location showed a very large gloss change visible to the naked eye.

[0159] Figure 3 In this context, b represents the coating composition of Example 1 of the present invention, which exhibits a small change in gloss after Crock-meter testing, less than 20%.

[0160] Denim abrasion resistance test

[0161] Test standard: ASTM D6279

[0162] Testing equipment: Taber Linear Abraser 5700 / Taber Linear Abraser 5900, Levi's 501 denim

[0163] Test method: 500g load, 25.4mm stroke, 60 revolutions / minute speed. Use denim (Levi's 501) to rub the coated surface for 2000 revolutions (including three methods: dry rubbing, wet rubbing with deionized water, and rubbing with artificial sweat). The grade is determined by the appearance change of the coating after rubbing. Only a few scratches or color changes visible to the naked eye are considered as passing the test.

[0164] Test results are as follows Figure 4 As shown:

[0165] Figure 4 In the figure, 'a' represents the coating prepared by Comparative Example 1. After the denim abrasion resistance test, it showed more scratches and greater color changes when wet abrasion and abrasion with artificial sweat, and therefore failed the test.

[0166] Figure 4 In the figure, b refers to the coating composition of Example 1 of the present invention. After the denim abrasion resistance test, it showed very few scratches and almost no color change, and thus passed the test.

[0167] Gloss and gloss stability

[0168] Gloss test standard ASTM D523

[0169] Instrument: BYK MODEL4520 gloss meter

[0170] When the mixing speed is in the range of 400~1000 rpm and the baking time is from 10 minutes to 8 hours, the gloss change is small, and the gloss change of the coating compositions in Examples 1-6 is less than 0.5 Gu.

[0171] feel

[0172] The test was conducted using Example 1 as an example.

[0173] Test standard ASTM D1894

[0174] Instrument: Dynamic and static friction coefficient testing machine

[0175] Static friction coefficient: 0.21

[0176] Coefficient of kinetic friction: 0.20

[0177] Conclusion: It has a smooth feel and low coefficients of dynamic and static friction.

[0178] Non-sticky

[0179] The cured coatings formed by the coating compositions of Examples 1-6 do not become sticky after being placed at 40-50°C for more than 12 months, demonstrating excellent stability.

[0180] Chemical resistance dyeing test

[0181] The tests were conducted using Comparative Example 2 and Example 4 as examples.

[0182] Chemical resistance staining test method: Apply easily staining chemicals such as Heinz ketchup (chemical 1), Starbucks coffee (chemical 2), aged vinegar (chemical 3), HERO red ink (chemical 4), PAPKER black ink (chemical 5), and indigo (CAS). 482- 89-3(Chemical 6) is applied to the coating surface and then placed in an environment of 25°C for 48 hours. After that, the surface is wiped with a cloth to visually observe the traces / color difference to check the color difference.

[0183] Test results are as follows Figure 5 As shown, Figure 5 a corresponds to a ratio of 2 and Figure 5 b corresponds to Example 4. Results were compared visually and by chemical staining color difference (measured using a commercially available X-rite Ci6X colorimeter) (Table 3). Example 4 showed better stain resistance than Comparative Example 2.

[0184] Table 3. Antifouling properties (resistance to easily dyed chemicals) and color difference values ​​of the water-based coating compositions of the present invention.

[0185]

[0186] Flexibility test

[0187] The tests were conducted using Comparative Example 2 and Example 4 as examples.

[0188] Flexibility testing method:

[0189] The coating is bent along the cylindrical axis, starting from the cylindrical axis with the largest diameter and gradually decreasing the diameter until cracks appear in the coating.

[0190] Instrument: Elcometer US 1500

[0191] Test results: Comparative example 2 ( Figure 6 a) Unable to pass through a 1 / 8-inch cylindrical shaft, a crack appeared, Example 4 ( Figure 6 b) It can pass through a 1 / 8-inch cylindrical shaft without cracking.

Claims

1. A water-based two-component polyurethane coating composition, comprising a first component and a second component, wherein, The first component includes a silicone-modified polyacrylate polyol, and the second component includes a polyisocyanate. The silicon-modified polyacrylate polyols include polysiloxane-modified polyacrylate polyols.

2. The coating composition according to claim 1, wherein the silicon content in the silicon-modified polyacrylate polyol is 5-20 wt% of the solid weight of the silicon-modified polyacrylate polyol.

3. The coating composition according to claim 1 or 2, wherein the silicone-modified polyacrylate polyol has a weight-average molecular weight of 3000-12000, a hydroxyl value greater than 50 mgKOH / g, and a glass transition temperature of 40 to 90°C.

4. The coating composition according to any one of claims 1-3, wherein the polysiloxane-modified polyacrylate polyol comprises a polysiloxane containing a single-terminal unsaturated double bond.

5. The coating composition according to any one of claims 1-4, wherein the first component further comprises silicone-modified polyurethane, wherein the silicone-modified polyurethane comprises polysiloxane-modified polyurethane.

6. The coating composition of claim 5, wherein the polysiloxane-modified polyurethane comprises a polysiloxane containing a single-terminal unsaturated double bond.

7. The coating composition according to any one of claims 5-6, wherein the silicon content in the silicone-modified polyurethane is 5-20 wt% of the solid weight of the silicone-modified polyurethane.

8. The coating composition according to any one of claims 5-7, wherein the silicone-modified polyurethane has a weight-average molecular weight of 3000-12000, a hydroxyl value of less than 40 mgKOH / g, and a glass transition temperature of -60 to -10°C.

9. The coating composition according to any one of claims 1-8, wherein the polyisocyanate comprises HDI type polyisocyanate and / or IPDI type polyisocyanate.

10. The coating composition according to any one of claims 1-9, wherein the polyisocyanate comprises 10 wt% or more of an HDI type polyisocyanate based on the total solid weight of the polyisocyanate.

11. The coating composition according to any one of claims 5-10, wherein the solid weight ratio of the silicone-modified polyacrylate polyol, the silicone-modified polyurethane, and the polyisocyanate is (13-30): (1-10): (10-25).

12. The coating composition according to any one of claims 5-10, wherein the weight ratio of the silicone-modified polyacrylate polyol and the silicone-modified polyurethane and the polyisocyanate is (8-22): (6-18): (10-25).

13. The coating composition according to any one of claims 1-12, wherein the molar ratio of the NCO group in the second component to the OH group in the first component is 0.8:1-2.0:

1.

14. The coating composition according to any one of claims 1-13, wherein the first component and the second component form a network structure comprising polysiloxane.

15. The coating composition according to any one of claims 1-14, comprising 5-40 wt% silicon content based on the total solid weight of the coating composition.

16. The coating composition according to any one of claims 1-15, further comprising 4 to 10 wt% of matting agent based on the total weight of the coating composition.

17. The coating composition of claim 16, wherein the coating formed by the coating composition has a gloss of less than 10 GU at a 60-degree angle.

18. The coating composition according to any one of claims 1-17, having a VOC content (excluding water) of not more than 300 g / L.

19. The coating composition according to any one of claims 1-18, which can be cured at 80°C for 6 hours.

20. Use of the waterborne two-component polyurethane coating composition according to any one of claims 1-19 for forming a coating with low surface energy and / or high water contact angle on a substrate surface.

21. The use as claimed in claim 20, wherein the coating has a strength of no more than 30 J / m 2 The surface energy and / or at least 95° water contact angle, wherein the surface energy and water contact angle are determined with reference to ASTM D7490-2013.

22. A coated substrate comprising a substrate and an aqueous two-component polyurethane coating composition as described in any one of claims 1-19 coated on at least a portion of the substrate.

23. The use or coated substrate as claimed in any one of claims 20-22, wherein the substrate comprises plastic and / or metal.

24. The use or coated substrate as described in any one of claims 20-23, wherein the substrate includes an electronic product surface.

25. The use or coated substrate as described in any one of claims 20-24, wherein the coating formed by the aqueous two-component polyurethane coating composition has a dry film thickness of 10-50 μm.

26. The use or coated substrate as described in any one of claims 20-25, wherein the coating formed by the aqueous two-component polyurethane coating composition has a gloss of less than 10 GU at a 60-degree angle.

27. The use or coated substrate as described in any one of claims 20-26, wherein the coating formed by the aqueous two-component polyurethane coating composition comprises a polysiloxane network structure.

28. An electronic product having at least a portion of its surface coated with the water-based two-component polyurethane coating composition as described in claims 1-19, or comprising a coated substrate as described in claims 22-27.

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