Radiation refrigeration coating system

Abstract

The invention relates to a main coating composition and a radiative cooling coating system which is particularly suitable for building exterior walls.

Description

Technical Field

[0001] This invention relates to a main coating composition and a radiation-cooled coating system, which is particularly suitable for building exterior walls. Background Technology

[0002] With the continuous upgrading of national building energy efficiency standards and the advancement of the "dual carbon" target, the performance requirements of exterior wall thermal insulation coatings, as key materials for reducing building energy consumption, are becoming increasingly stringent. Existing reflective thermal insulation coatings mainly achieve cooling by increasing solar reflectivity, but their energy regulation capabilities are limited and can no longer meet the demands of current high-energy-saving scenarios. Radiative cooling thermal insulation coatings, which can radiate heat into space through an 8-13μm atmospheric window, have become an important development direction for energy-saving coatings. Their principle mainly includes two points: First, they possess ultra-high solar reflectivity. The core material, due to its high electron band gap, absorbs almost no ultraviolet and visible light. Combined with specific particle sizes and distributions that cover all wavelengths of the solar spectrum, it can reflect more than 92% of sunlight, significantly reducing heat input. Second, they achieve efficient infrared thermal radiation. The core material exhibits strong phonon resonance within the 8-13μm atmospheric transparent window, enabling it to efficiently radiate its own heat outwards. Furthermore, this radiation can penetrate the atmosphere and reach outer space without being absorbed or reflected by the atmosphere.

[0003] The concept of using coatings to achieve radiative cooling has been proposed, but its practical application still faces many bottlenecks. Traditional radiative cooling coatings, in order to obtain high solar reflectivity and atmospheric window emissivity, typically require the addition of large amounts of functional fillers, resulting in extremely low resin content and excessively high pigment volume concentration (PVC). This formulation design leads to a loose film structure, resulting in poor mechanical strength, weak aging resistance, and susceptibility to cracking and chalking. Furthermore, the numerous surface pores make it highly susceptible to attracting dust, oil, and other contaminants. Once covered by contaminants, the coating's solar reflectivity drops drastically, almost completely eliminating the radiative cooling effect, severely impacting its service life and user experience. This has prevented the widespread application of this type of coating on exterior walls.

[0004] Therefore, developing a radiation-cooled exterior wall coating system that possesses both high-efficiency radiation cooling capability and excellent mechanical properties, aging resistance, and stain resistance, and can meet the needs of practical engineering applications, has become an urgent technical challenge in the field of building energy-saving coatings. It is of great significance for promoting the industrial application of radiation cooling technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing radiative cooling coatings, such as poor film performance, easy contamination, and easy failure of cooling effect. It provides a main coating composition that combines high-efficiency radiative cooling capability with excellent service performance. In particular, it is a multi-layer structure exterior wall coating system containing a main coating obtained from this main coating composition. Through the functional synergy of each layer and component innovation, this system can achieve a unity of "high cooling efficiency, strong mechanical properties, and long-term stain resistance", meeting the needs of large-scale exterior wall applications.

[0006] In one aspect, the present invention relates to a main coating composition comprising barium sulfate or aluminum oxide modified with organic and inorganic materials, and an aqueous resin as a resin in the main coating emulsion.

[0007] In another aspect, the present invention relates to a multi-coating system comprising a primer layer and a main coating layer, particularly comprising a primer layer, a main coating layer and a topcoat layer, wherein the main coating layer is derived from a main coating composition according to the present invention.

[0008] In another aspect, the present invention relates to the use of organic and inorganic modified barium sulfate or aluminum oxide in improving radiative cooling of coating systems. Attached image description:

[0009] Figure 1 The infrared spectra of the modified barium sulfate used in the examples and the unmodified barium sulfate used in the comparative examples are shown.

[0010] Figure 2 A schematic diagram of a multi-coat system including a primer layer and a main coating layer is shown in Example 2.

[0011] Figure 3 This diagram illustrates a multi-coat system comprising a primer layer, a main coating layer, and a topcoat layer, as shown in Example 3. Detailed Implementation

[0012] Main coating composition

[0013] This invention relates to a main coating composition comprising barium sulfate or aluminum oxide modified with organic and inorganic materials, and an aqueous resin as a resin in the main coating emulsion.

[0014] In one embodiment, the main coating composition comprises 40-85% by weight, preferably 45-80% by weight, more preferably 50-75% by weight, and most preferably 60-70% by weight, of organic and inorganic modified barium sulfate or aluminum oxide, based on the total weight of the main coating composition.

[0015] In one embodiment, the particle size (D50) of the organic and inorganic modified barium sulfate or alumina is 0.1-8 μm, preferably 0.2-7 μm, more preferably 0.3-6.5 μm, and most preferably 0.4-6 μm.

[0016] In one embodiment, the L value of the organic and inorganic modified barium sulfate or alumina is at least 85, preferably at least 90, more preferably at least 93, and most preferably at least 97.

[0017] In one embodiment, the inorganic material may be silicon dioxide.

[0018] In one embodiment, the amount of the inorganic material may be 0.1-5% by weight, preferably 0.2-4.5% by weight, more preferably 0.5-3.5% by weight, and most preferably 0.8-3.2% by weight, based on the total weight of the organic material and the modified barium sulfate or alumina.

[0019] In one embodiment, the organic material may be selected from fatty acid (salt) compounds (such as sodium stearate / calcium, sodium palmitate), silane coupling agents, and polymers (such as polyacrylates, polyolefins), with silane coupling agents being preferred.

[0020] In one embodiment, the amount of the organic material may be 0.05-2.5 wt%, preferably 0.1-2 wt%, more preferably 0.12-1.5 wt%, and most preferably 0.15-1.2 wt%, based on the total weight of the organic material and the inorganic material-modified barium sulfate or alumina.

[0021] In one embodiment, the organic and inorganic modified barium sulfate or alumina has a silica inorganic layer and a silane coupling agent organic layer.

[0022] In one embodiment, the main coating composition contains 2-20% by weight, preferably 3-12% by weight, more preferably 4-10% by weight, and most preferably 5-7% by weight of an aqueous resin as the resin in the main coating emulsion, based on the total weight of the main coating composition.

[0023] In one embodiment, the aqueous resin may be selected from an inorganic hybrid modified acrylic resin or a combination of an inorganic hybrid modified acrylic resin and an acrylic resin or a fluorocarbon resin.

[0024] In one embodiment, the inorganic hybrid modified acrylic resin is an acrylic resin modified with nano-silica.

[0025] In one embodiment, the inorganic hybrid modified acrylic resin has a hybridization ratio of 5-30% by weight, preferably 7-28% by weight, more preferably 15-25% by weight, and most preferably 18-22% by weight.

[0026] In one embodiment, the glass transition temperature of the inorganic hybrid modified acrylic resin is 10-40°C, preferably 15-35°C, more preferably 18-33°C, and most preferably 20-30°C.

[0027] In one embodiment, the main coating composition contains 0.1-5% by weight, preferably 0.2-2.5% by weight, more preferably 0.5-2% by weight, and most preferably 0.8-1.5% by weight of a dispersant, based on the total weight of the main coating composition.

[0028] In one embodiment, the dispersant is selected from potassium copolyacrylate dispersants, ammonium homopolyacrylate dispersants, or sodium homopolyacrylate dispersants.

[0029] In one embodiment, the main coating composition comprises 1-20% by weight, preferably 3-15% by weight, more preferably 5-12% by weight, and most preferably 7-10% by weight of nanocellulose pulp, based on the total weight of the main coating composition.

[0030] In one embodiment, the concentration of the nanocellulose pulp can be 1-10% by weight, preferably 1.5-8% by weight, more preferably 2-6% by weight, and most preferably 2.5-4% by weight.

[0031] According to the present invention, nanocellulose is a fibrous polymer matrix with a diameter of less than 100 nm extracted from natural cellulose. Cellulose fibers can laterally dissociate in amorphous regions existing along their axes to form nanoscale and highly crystalline defect-free rod-shaped cellulose nanocrystals.

[0032] In one embodiment, the nanocellulose may be selected from cellulose nanocrystals, cellulose nanofibers, electrospun fibers, and bacterial cellulose.

[0033] In one embodiment, the nanocellulose fibers have a length of 10 nm to 100 μm and a diameter of 5 to 100 nm.

[0034] According to the present invention, the main coating composition may further include thickeners, bactericides, wetting agents, defoamers, antifreeze agents, film-forming aids, preservatives and / or pH adjusters.

[0035] In one embodiment, the thickener may be selected from an alkali-swellable thickener, an associative alkali-swellable thickener, or a polyurethane thickener. In one embodiment, the amount of the thickener may be 0.1-1.5 wt%, preferably 0.15-1 wt%, more preferably 0.2-0.8 wt%, and most preferably 0.3-0.6 wt%, based on the total weight of the main coating composition.

[0036] In one embodiment, the thickener may also be selected from hydroxyethyl cellulose ether and / or hydrophobically modified cellulose ether, such as hydrophobically modified hydroxyethyl cellulose ether. In a preferred embodiment, hydroxyethyl cellulose ether is used. The molecular weight of the cellulose ether may be 20,000 to 150,000 (e.g., 25,000, 30,000, 40,000, 50,000, 60,000, 80,000, 100,000, or 120,000) or 25,000 to 120,000. The amount of the cellulose ether may be 0.005-0.5% by weight, preferably 0.01-0.1% by weight, more preferably 0.02-0.08% by weight, and most preferably 0.03-0.06% by weight, based on the total weight of the main coating composition.

[0037] In one embodiment, the bactericide may be selected from silver salts, zinc salts, hexadecylpyridinium chloride and / or triclosan, 2-[(hydroxymethyl)amino]ethanol, 2-[(hydroxymethyl)amino]2-methyl-1-propanol, o-phenylphenol, sodium salts, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one (MIT), 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-octyl-4-isothiazolin-3-one (OIT), 4,5-dichloro-2-n-octyl-3-isothiazolinone, and acceptable salts thereof and combinations thereof. In one embodiment, the amount of the bactericide may be 0.005-0.5% by weight, preferably 0.01-0.1% by weight, more preferably 0.02-0.08% by weight, and most preferably 0.03-0.06% by weight, based on the total weight of the main coating composition.

[0038] In one embodiment, the wetting agent may be selected from siloxanes, fluorinated compounds, monocarboxylic acid esters, phosphate esters, polyacrylic acid and its copolymers such as polybutyl acrylate and polyurethane. In one embodiment, the amount of the wetting agent may be 0.01-1 wt%, preferably 0.02-0.6 wt%, more preferably 0.05-0.2 wt%, and most preferably 0.08-0.15 wt%, based on the total weight of the main coating composition.

[0039] In one embodiment, the defoamer may be selected from TEGO FOAMEX 8030, Foamaster MO 2150, Foamaster MO 2190, Drewplus T-1201, Drewplus 1-191, and Rhodoline 6681. In one embodiment, the amount of the defoamer may be 0.01-1.5% by weight, preferably 0.05-0.8% by weight, more preferably 0.08-0.5% by weight, and most preferably 0.1-0.4% by weight, based on the total weight of the main coating composition.

[0040] In one embodiment, the antifreeze may be selected from ethylene glycol, propylene glycol, urea, and glycerin. In one embodiment, the amount of the antifreeze may be 0.1-2.5 wt%, preferably 0.5-2.0 wt%, more preferably 1.0-1.8 wt%, and most preferably 1.2-1.6 wt%, based on the total weight of the main coating composition.

[0041] In one embodiment, the film-forming aid may be selected from alcohol esters, such as dodecyl alcohol ester (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, commonly known as TEXANOL), hexadecyl alcohol ester, etc.; it may also be selected from alcohol ethers, such as propylene glycol butyl ether (PNB), propylene glycol methyl ether (PM), ethylene glycol butyl ether (EB), etc.; or it may be selected from other types of environmentally friendly film-forming aids such as Eastman Optifilm. TM Series, dipropylene glycol methyl ether acetate (DPMA), etc. In one embodiment, the amount of the film-forming aid may be 0.1-2.5 wt%, preferably 0.5-2.0 wt%, more preferably 0.8-1.8 wt%, and most preferably 1.0-1.6 wt%, based on the total weight of the main coating composition.

[0042] In one embodiment, the preservative may be selected from 1,2-benzisothiazolin-3-one and / or 2-methyl-2H-isothiazolin-3-one or sodium benzoate or benzoic acid. In one embodiment, the amount of the preservative may be 0.01-1.5 wt%, preferably 0.05-0.8 wt%, more preferably 0.1-0.5 wt%, and most preferably 0.2-0.4 wt%, based on the total weight of the main coating composition.

[0043] In one embodiment, the pH adjuster may be selected from alkalis, such as sodium hydroxide, potassium hydroxide, amino alcohols, monoethanolamine (MEA), diethanolamine (DEA), 2-(2-aminoethoxy)ethanol, diisopropanolamine (DIPA), 2-amino-2-methyl-1-propanol (AMP), ammonia, and combinations thereof. In one embodiment, the amount of the pH adjuster may be 0.01-1.5 wt%, preferably 0.05-0.8 wt%, more preferably 0.06-0.5 wt%, and most preferably 0.08-0.2 wt%, based on the total weight of the main coating composition.

[0044] In one embodiment, the main coating composition, after dispersion, has a fineness ≤50μm, a viscosity of 90-110KU at 25°C, and / or a solid content >50% by mass.

[0045] The preparation of the main coating composition according to the present invention may include the following steps: turning on the stirring equipment, first adding deionized water and nanocellulose slurry and stirring, then adding bactericide, wetting agent, dispersant, and a portion of defoamer in sequence and stirring, then adding barium sulfate or alumina modified with organic and inorganic materials, hydroxyethyl cellulose ether and pH adjuster in sequence, cleaning the tank wall and dispersing at high speed to a fineness ≤50μm; reducing the stirring speed, adding film-forming aid, antifreeze and water-based resin in sequence and stirring, then adding the remaining portion of defoamer and preservative; slowly adding thickener and stirring until the viscosity reaches 90-110KU.

[0046] The main coating composition according to the present invention has both good solar reflectivity and 8-13μm atmospheric window radiation capability, and also has excellent dispersion stability and application performance.

[0047] Multi-coating system

[0048] The present invention relates to a multi-coating system comprising a primer layer and a main coating layer, wherein the main coating layer is derived from a main coating composition according to the present invention.

[0049] In one implementation, the main coating application can be carried out using a roller coating with multiple layers or a one-time thick spraying process.

[0050] In one embodiment, the dry film thickness of the main coating is 100-350 μm, preferably 120-330 μm, more preferably 130-320 μm, and most preferably 150-300 μm.

[0051] According to the present invention, the primer layer is obtained from a primer composition, wherein the primer composition comprises titanium dioxide, primer emulsion and dispersant.

[0052] In one embodiment, the titanium dioxide is rutile, with a particle size distribution of 0.2-0.4 μm and an L value ≥ 95. In one embodiment, the amount of titanium dioxide used is 5-30% by weight, preferably 7-28% by weight, more preferably 15-25% by weight, and most preferably 18-22% by weight, based on the total weight of the primer composition.

[0053] In one embodiment, the resin in the primer emulsion is selected from styrene-acrylic resin and silicone-modified acrylic resin. In one embodiment, the amount of resin in the primer emulsion is 5-35% by weight, preferably 10-30% by weight, more preferably 15-25% by weight, and most preferably 18-20% by weight, based on the total weight of the primer composition.

[0054] In one embodiment, the dispersant is an acrylic dispersant selected from potassium copolyester of acrylic acid-maleic anhydride, sodium homopolymer of acrylic acid, and ammonium homopolymer of acrylic acid. In one embodiment, the amount of the dispersant is 0.05-1.5 wt%, preferably 0.1-1.0 wt%, more preferably 0.3-0.9 wt%, and most preferably 0.5-0.7 wt%, based on the total weight of the primer composition.

[0055] In one embodiment, the primer composition further comprises fillers, thickeners, bactericides, wetting agents, defoamers, antifreeze agents, film-forming aids, preservatives, and / or pH adjusters.

[0056] In one embodiment, the filler may be selected from inorganic minerals such as wollastonite, calcium carbonate, feldspar, kaolin, talc, mica, magnesite, calcite, magnesium carbonate, dolomite, calcium sulfate, and silica. The filler may be used as a single component. However, in practice, filler mixtures have been found particularly suitable, examples being calcium carbonate / wollastonite, calcium carbonate / kaolin, or calcium carbonate / talc. In one embodiment, the filler may be used in an amount of 5-28% by weight, preferably 7-25% by weight, more preferably 10-20% by weight, and most preferably 12-18% by weight, based on the total weight of the primer composition.

[0057] In one embodiment, the thickener may be selected from an alkali-swellable thickener, an associative alkali-swellable thickener, or a polyurethane thickener. In one embodiment, the amount of the thickener may be 0.1-1.5 wt%, preferably 0.15-1 wt%, more preferably 0.2-0.8 wt%, and most preferably 0.25-0.5 wt%, based on the total weight of the primer composition.

[0058] In one embodiment, the thickener may also be selected from hydroxyethyl cellulose ether and / or hydrophobically modified cellulose ether, such as hydrophobically modified hydroxyethyl cellulose ether. In a preferred embodiment, hydroxyethyl cellulose ether is used. The molecular weight of the cellulose ether may be 20,000 to 150,000 (e.g., 25,000, 30,000, 40,000, 50,000, 60,000, 80,000, 100,000, or 120,000) or 25,000 to 120,000. The amount of the cellulose ether may be 0.05-2% by weight, preferably 0.1-1% by weight, more preferably 0.2-0.8% by weight, and most preferably 0.3-0.6% by weight, based on the total weight of the primer composition.

[0059] In one embodiment, the bactericide may be selected from silver salts, zinc salts, hexadecylpyridinium chloride and / or triclosan, 2-[(hydroxymethyl)amino]ethanol, 2-[(hydroxymethyl)amino]2-methyl-1-propanol, o-phenylphenol, sodium salts, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one (MIT), 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-octyl-4-isothiazolin-3-one (OIT), 4,5-dichloro-2-n-octyl-3-isothiazolinone, and acceptable salts thereof and combinations thereof. In one embodiment, the amount of the bactericide may be 0.005-0.5% by weight, preferably 0.01-0.1% by weight, more preferably 0.02-0.08% by weight, and most preferably 0.03-0.06% by weight, based on the total weight of the primer composition.

[0060] In one embodiment, the wetting agent may be selected from siloxanes, fluorinated compounds, monocarboxylic acid esters, phosphate esters, polyacrylic acid and its copolymers such as polybutyl acrylate and polyurethane. In one embodiment, the amount of the wetting agent may be 0.1-1.5 wt%, preferably 0.15-1 wt%, more preferably 0.2-0.8 wt%, and most preferably 0.25-0.5 wt%, based on the total weight of the primer composition.

[0061] In one embodiment, the defoamer may be selected from TEGO FOAMEX 8030, Foamaster MO2150, Foamaster MO 2190, Drewplus T-1201, Drewplus 1-191, and Rhodoline 6681. In one embodiment, the amount of the defoamer may be 0.1-1.5% by weight, preferably 0.15-1% by weight, more preferably 0.2-0.8% by weight, and most preferably 0.25-0.5% by weight, based on the total weight of the primer composition.

[0062] In one embodiment, the antifreeze may be selected from ethylene glycol, propylene glycol, urea, and glycerin. In one embodiment, the amount of the antifreeze may be 0.1-2.5 wt%, preferably 0.5-2.0 wt%, more preferably 1.0-1.8 wt%, and most preferably 1.2-1.6 wt%, based on the total weight of the primer composition.

[0063] In one embodiment, the film-forming aid may be selected from alcohol esters, such as dodecyl alcohol ester (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, commonly known as TEXANOL), hexadecyl alcohol ester, etc.; it may also be selected from alcohol ethers, such as propylene glycol butyl ether (PNB), propylene glycol methyl ether (PM), ethylene glycol butyl ether (EB), etc.; or it may be selected from other types of environmentally friendly film-forming aids such as Eastman Optifilm. TM Series, dipropylene glycol methyl ether acetate (DPMA), etc. In one embodiment, the amount of the film-forming aid may be 1-10% by weight, preferably 1.5-8% by weight, more preferably 2-6% by weight, and most preferably 2.5-4% by weight, based on the total weight of the primer composition.

[0064] In one embodiment, the preservative may be selected from 1,2-benzisothiazolin-3-one and / or 2-methyl-2H-isothiazolin-3-one or sodium benzoate or benzoic acid. In one embodiment, the amount of the preservative may be 0.01-1.5% by weight, preferably 0.05-0.8% by weight, more preferably 0.1-0.5% by weight, and most preferably 0.2-0.45% by weight, based on the total weight of the primer composition.

[0065] In one embodiment, the pH adjuster may be selected from alkalis, such as sodium hydroxide, potassium hydroxide, amino alcohols, monoethanolamine (MEA), diethanolamine (DEA), 2-(2-aminoethoxy)ethanol, diisopropanolamine (DIPA), 2-amino-2-methyl-1-propanol (AMP), ammonia, and combinations thereof. In one embodiment, the amount of the pH adjuster may be 0.01-1.5 wt%, preferably 0.05-0.8 wt%, more preferably 0.06-0.5 wt%, and most preferably 0.08-0.3 wt%, based on the total weight of the primer composition.

[0066] In one implementation, the primer layer is applied using a suitable roller coating, spraying, or brushing process.

[0067] In one embodiment, the dry film thickness of the primer layer is 30-120 μm, preferably 35-100 μm, more preferably 40-80 μm, and most preferably 45-50 μm.

[0068] According to the present invention, the multi-coating system may further include a topcoat layer.

[0069] According to the present invention, the topcoat layer is obtained from a topcoat composition comprising a topcoat emulsion and fluorosilicone additives.

[0070] In one embodiment, the resin in the topcoat emulsion is selected from acrylic resins, fluorocarbon resins, silicone-modified resins, and fluorosilicone-modified acrylic resins. In one embodiment, the amount of resin in the topcoat emulsion is 5-40% by weight, preferably 10-35% by weight, more preferably 15-30% by weight, and most preferably 18-25% by weight, based on the total weight of the topcoat composition.

[0071] In a preferred embodiment, the resin in the topcoat emulsion is a fluorosilicone modified acrylic resin, wherein the mass percentage of fluorine is ≥20% and the mass percentage of silicon is ≥5%.

[0072] In one embodiment, the glass transition temperature of the resin in the topcoat emulsion is 20-30°C.

[0073] According to the present invention, the fluorosilicone additive is a fluorine-containing or silicon-containing additive. In one embodiment, the fluorosilicone additive is a fluorine-modified organosilicon. In one embodiment, the amount of the fluorosilicone additive is 1-20% by weight, preferably 3-15% by weight, more preferably 5-12% by weight, and most preferably 8-11% by weight, based on the total weight of the topcoat composition.

[0074] In one embodiment, the topcoat composition further comprises a bactericide, a defoamer, an antifreeze agent, a film-forming aid, a preservative, and a pH adjuster.

[0075] In one embodiment, the bactericide may be selected from silver salts, zinc salts, hexadecylpyridinium chloride and / or triclosan, 2-[(hydroxymethyl)amino]ethanol, 2-[(hydroxymethyl)amino]2-methyl-1-propanol, o-phenylphenol, sodium salts, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one (MIT), 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-octyl-4-isothiazolin-3-one (OIT), 4,5-dichloro-2-n-octyl-3-isothiazolinone, and acceptable salts thereof and combinations thereof. In one embodiment, the amount of the bactericide may be 0.005-0.5% by weight, preferably 0.01-0.1% by weight, more preferably 0.02-0.08% by weight, and most preferably 0.03-0.06% by weight, based on the total weight of the topcoat composition.

[0076] In one embodiment, the defoamer may be selected from TEGO FOAMEX 8030, Foamaster MO2150, Foamaster MO2190, Drewplus T-1201, Drewplus 1-191, and Rhodoline 6681. In one embodiment, the amount of the defoamer may be 0.01-1% by weight, preferably 0.02-0.8% by weight, more preferably 0.05-0.6% by weight, and most preferably 0.1-0.3% by weight, based on the total weight of the topcoat composition.

[0077] In one embodiment, the antifreeze may be selected from ethylene glycol, propylene glycol, urea, and glycerin. In one embodiment, the amount of the antifreeze may be 0.1-1.5 wt%, preferably 0.15-1 wt%, more preferably 0.2-0.8 wt%, and most preferably 0.25-0.6 wt%, based on the total weight of the topcoat composition.

[0078] In one embodiment, the film-forming aid may be selected from alcohol esters, such as dodecyl alcohol ester (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, commonly known as TEXANOL), hexadecyl alcohol ester, etc.; it may also be selected from alcohol ethers, such as propylene glycol butyl ether (PNB), propylene glycol methyl ether (PM), ethylene glycol butyl ether (EB), etc.; or it may be selected from other types of environmentally friendly film-forming aids such as Eastman Optifilm. TM Series, dipropylene glycol methyl ether acetate (DPMA), etc. In one embodiment, the amount of the film-forming aid may be 0.1-5% by weight, preferably 0.5-3% by weight, more preferably 0.8-2.5% by weight, and most preferably 1-2% by weight, based on the total weight of the topcoat composition.

[0079] In one embodiment, the preservative may be selected from 1,2-benzisothiazolin-3-one and / or 2-methyl-2H-isothiazolin-3-one or sodium benzoate or benzoic acid. In one embodiment, the amount of the preservative may be 0.01-1.5% by weight, preferably 0.05-0.8% by weight, more preferably 0.1-0.5% by weight, and most preferably 0.2-0.45% by weight, based on the total weight of the topcoat composition.

[0080] In one embodiment, the pH adjuster may be selected from alkalis, such as sodium hydroxide, potassium hydroxide, amino alcohols, monoethanolamine (MEA), diethanolamine (DEA), 2-(2-aminoethoxy)ethanol, diisopropanolamine (DIPA), 2-amino-2-methyl-1-propanol (AMP), ammonia, and combinations thereof. In one embodiment, the amount of the pH adjuster may be 0.01-1.5 wt%, preferably 0.05-0.8 wt%, more preferably 0.06-0.5 wt%, and most preferably 0.08-0.3 wt%, based on the total weight of the topcoat composition.

[0081] In one embodiment, the viscosity of the topcoat composition at 25°C is 50-80 KU.

[0082] In one embodiment, the topcoat layer is applied using a roller coating or spray coating process.

[0083] In one embodiment, the dry film thickness of the cover layer is 10-60 μm, preferably 12-45 μm, more preferably 15-35 μm, and most preferably 20-25 μm.

[0084] The coating system according to the present invention does not require special equipment for the construction of each layer, and after drying and film formation, the interlayer adhesion level between the primer layer, the main coating layer and the optional topcoat layer is ≤1 (cross-cut test), with no peeling or wrinkling.

[0085] The advantages of the main coating of this invention are reflected in the use of dual-modified barium sulfate or alumina, inorganic hybrid modified acrylic emulsion paint, and nanocellulose pulp, which solves the problem of high reflectivity but poor physical properties of radiative cooling coatings. The main coating of this invention containing modified barium sulfate has superior reflectivity and radiation performance. According to the test results of T / CECS10378-2024 "Radiative Cooling Coatings for Buildings" and JG / T 235-2014 "Reflective Thermal Insulation Coatings for Buildings", the solar reflectance (TSR) is ≥0.95, the emissivity of the 8-13μm atmospheric window is ≥0.94, the hemispherical emissivity is ≥0.92, the near-infrared reflectance is ≥0.90, and the coating itself still maintains a good solar reflectance after contamination, with a solar reflectance reduction rate of ≤5% after contamination. While achieving the above reflective properties, the main coating film also exhibits superior physical properties. Tested according to GB / T 9755-2024 "Synthetic Resin Emulsion Wall Coatings" standard, the film withstands ≥10,000 washes, has an artificial weathering resistance of ≥2,000 hours, and exhibits a stain resistance of ≤3%. Furthermore, this main coating solves the problems of easy cracking during application and thickening after storage in this type of coating. A single coat of 600μm does not crack, and after one month of heat storage, the viscosity increase is ≤10KU. The main coating film containing modified alumina of this invention exhibits superior reflectivity and radiation properties, with a solar reflectance (TSR) ≥0.93, hemispherical emissivity ≥0.89, near-infrared reflectance ≥0.87, and wash resistance >5,000 times.

[0086] The synergistic advantages of the coating system of this invention are reflected in the following: after the high-reflectivity primer layer and the radiative cooling main coating layer are combined (double coating system), the reflectivity of the coating film meets the requirements of T / CECS10378-2024 "Radiative Cooling Coatings for Buildings" and JG / T 235-2014 "Reflective Thermal Insulation Coatings for Buildings". The test results are as follows: solar reflectance ≥ 0.95, 8-13μm atmospheric window emissivity ≥ 0.94, hemispherical emissivity ≥ 0.92, near-infrared reflectance ≥ 0.90, and the coating itself still maintains a good solar reflectance after contamination, with a solar reflectance reduction rate of ≤ 5% after contamination. The physical properties of the double-coated layer meet the GB / T 9755-2024 standard for "Synthetic Resin Emulsion Exterior Wall Coatings". It also has a wash resistance of ≥10,000 times, an artificial aging resistance of ≥2,000 hours, and a stain resistance of ≤3%, all of which are far higher than the requirements for superior grade exterior wall coatings. After adding the topcoat layer (three-coat system), the complete system meets the GB / T 9779 standard for "Multi-layer Architectural Coatings". The paint film has good stain resistance, better durability, artificial weathering resistance of ≥2,500 hours, and a longer-lasting cooling effect.

[0087] The coating system of this invention is suitable as an external coating, i.e., for applications exposed to sunlight, such as (large) vehicles and aircraft, as well as multi-purpose vehicles in industrial applications, railways, agriculture, and construction, wind turbines, bridges, power masts, fuel tanks, containers, pipelines, power plants, chemical plants, ships, cranes, halls, roofs, furniture, windows, doors, and wooden floors, and is particularly suitable for use in automotive paints for finishing. The coating system of this invention is especially suitable for building exteriors.

[0088] The coating system of this invention can achieve efficient radiative cooling while ensuring the strength and stain resistance of the paint film, thus solving the bottleneck of poor physical properties and poor applicability of similar products.

[0089] use

[0090] This invention relates to the use of organic and inorganic modified barium sulfate or aluminum oxide in improving radiative cooling of coating systems.

[0091] In one embodiment, the organic and inorganic materials modified barium sulfate or aluminum oxide are as described above in the main coating composition.

[0092] In one embodiment, the coating system is as described above in the multi-coating system.

[0093] Example:

[0094] The following examples are for illustrative purposes only and are not intended to limit the invention. The amounts of each substance in the examples are based on parts by weight.

[0095] The raw materials are shown in Table 1 below:

[0096] Table 1:

[0097]

[0098]

[0099] Remark:

[0100] 1. Modified Barium Sulfate: Modified with γ-glycidyl etheroxypropyltrimethoxysilane and silica. The modification amount of γ-glycidyl etheroxypropyltrimethoxysilane is approximately 0.2 wt%, and the modification amount of silica is approximately 0.9 wt%. Typical parameters: Barium sulfate content: ≥98 wt%; L value >98; D50: 0.5-0.7 μm; Oil absorption: 10-30 g / 100 g; Volatile matter at 105℃: <0.2 wt%. The infrared spectrum of modified barium sulfate is shown below. Figure 1 middle.

[0101] 2. Modified alumina CA200: Modified with γ-glycidyl etheroxypropyltrimethoxysilane and silica. The amount of γ-glycidyl etheroxypropyltrimethoxysilane modification is approximately 1 wt%, and the amount of silica modification is approximately 3 wt%. Typical parameters: Powder particle size D50: 5 μm, L value: 97.84.

[0102] 3. Modified alumina CA300: Modified with γ-glycidyl etheroxypropyltrimethoxysilane and silica. The amount of γ-glycidyl etheroxypropyltrimethoxysilane modification is approximately 1 wt%, and the amount of silica modification is approximately 3 wt%. Typical parameters: Powder particle size D50: 1.8 μm, L value: 98.8.

[0103] 4. Primer emulsion: Solid content: 48% by weight.

[0104] 5. Main coating emulsion: A nano-silica hybrid modified acrylic resin emulsion, with a nano-silica hybridization ratio of 20% by weight. Typical parameters are: solid content: 47% by weight; minimum film-forming temperature (MFT): 22℃; density: 1.09 g / cm³. 3 pH: 11-11.5.

[0105] 6. Topcoat emulsion: Solid content: 50% by weight.

[0106] Preparation Example 1 Primer

[0107] The amounts (parts by weight) of each component in the primer are shown in Table 2 below, and it is prepared as follows: First, add component 1 to the disperser and stir at 400 rpm. Then, slowly add components 2-7, increase the speed to 1000 rpm, and stir for 5 min. Add components 8-10, increase the stirring speed to 1500 rpm, and stir for 20 min. Reduce the speed to 800 rpm, slowly add components 11-16, stir for 10 min, and let it stand for 2 h before use.

[0108] Table 2: Primer Composition

[0109]

[0110]

[0111] Preparation Example 2 Main paint 1

[0112] The amounts (parts by weight) of each component in the main coating 1 are shown in Table 3 below, and they are added as follows: First, add components 1 and 2 in sequence to the disperser and stir at 800 rpm for 5 min; then add components 3-7 in sequence and stir for 3 min; increase the speed to 1200 rpm and add components 8-10 in sequence. After complete addition, clean the tank wall, increase the speed again to 1500 rpm, disperse for 30 min, and check the fineness <50 μm; reduce the stirring speed and add components 11-16 in sequence, where component 16 is diluted with deionized water at a ratio of 1:2 and then added slowly, stirring for 10 min, and then allowed to stand for 24 h before use.

[0113] Table 3: Composition of Main Coating 1

[0114] Serial Number raw materials Dosage 1 Deionized water 6.00 2 Nanocellulose pulp (3%) 8.00 3 bactericide 0.05 4 wetting agent 0.10 5 Dispersant a 0.20 6 Dispersant b 0.80 7 Emulsified mineral oil defoamer 0.15 8 Modified barium sulfate 68.00 9 Hydroxyethyl cellulose ether 0.05 10 pH adjuster 0.10 11 Film-forming aids 1.10 12 antifreeze 1.50 13 Main coating emulsion 13.00 14 Emulsified mineral oil defoamer 0.15 15 preservative 0.30 16 Associative alkali-swellable thickeners 0.50 total 100.00

[0115] Preparation Example 2' : Main coating 1'

[0116] The amounts (parts by weight) of each component in the main coating 1' are shown in Table 4 below, and they are added as follows: First, add components 1 and 2 in sequence to the disperser and stir at 800 rpm for 5 min; then add components 3-7 in sequence and stir for 3 min; increase the speed to 1200 rpm and add components 8-10 in sequence. After complete addition, clean the tank wall, increase the speed again to 1500 rpm, disperse for 30 min, and check the fineness <50 μm; reduce the stirring speed and add components 11-16 in sequence, where component 16 is diluted with deionized water at a ratio of 1:2 and then added slowly, stirring for 10 min, and then allowed to stand for 24 h before use.

[0117] Table 4: Composition of Main Coating 1'

[0118] Serial Number raw materials Dosage 1 Deionized water 6.00 2 3% Nanocellulose Pulp 8.00 3 bactericide 0.05 4 wetting agent 0.10 5 Dispersant a 0.20 6 Dispersant b 0.80 7 Emulsified mineral oil defoamer 0.15 8 Modified alumina CA200 68.00 9 Hydroxyethyl cellulose ether 0.05 10 pH adjuster 0.10 11 Film-forming aids 1.10 12 antifreeze 1.50 13 Main coating emulsion 13.00 14 Emulsified mineral oil defoamer 0.15 15 preservative 0.30 16 Associative alkali-swellable thickeners 0.50 total 100.00

[0119] Preparation Example 2” Main coating 1”

[0120] The amounts (parts by weight) of each component in “Main Coating 1” are shown in Table 5 below, and they are added as follows: First, add components 1 and 2 in sequence to the disperser and stir at 800 rpm for 5 min; then add components 3-7 in sequence and stir for 3 min; increase the speed to 1200 rpm and add components 8-10 in sequence. After complete addition, clean the tank wall, increase the speed again to 1500 rpm, disperse for 30 min, and check the fineness <50 μm; reduce the stirring speed and add components 11-16 in sequence, where component 16 is diluted with deionized water at a ratio of 1:2 and then added slowly, stirring for 10 min, and then allowed to stand for 24 h before use.

[0121] Table 5: Composition of Main Coating 1”

[0122] Serial Number raw materials Dosage 1 Deionized water 6.00 2 Nanocellulose pulp (3%) 8.00 3 bactericide 0.05 4 wetting agent 0.10 5 Dispersant a 0.20 6 Dispersant b 0.80 7 Emulsified mineral oil defoamer 0.15 8 Modified alumina CA300 68.00 9 Hydroxyethyl cellulose ether 0.05 10 pH adjuster 0.10 11 Film-forming aids 1.10 12 antifreeze 1.50 13 Main coating emulsion 13.00 14 Emulsified mineral oil defoamer 0.15 15 preservative 0.30 16 Associative alkali-swellable thickeners 0.50 total 100.00

[0123] Preparation Example 3 Topcoat

[0124] The amounts (parts by weight) of each component in the topcoat are shown in Table 6 below, and they are added as follows: First, add component 1 in a disperser and stir at 400 rpm; then add components 2-9 in sequence, increase the speed to 600 rpm, stir for 10 min, and let stand for 24 h before use.

[0125] Table 6: Composition of Topcoat

[0126]

[0127]

[0128] Example 1: Single-coat system including a main coating 1

[0129] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0130] 2. Application of the main coating: The main coating 1 prepared in Preparation Example 2 is applied to the substrate pretreated in step 1 using an airless spraying process with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying, and the substrate is cured for 8 hours until it is completely dry, with a dry film thickness of 160 μm.

[0131] Comparative Example 1: Comparative Single-Coat System 1 Containing Comparative Coating 1

[0132] The only difference between paint 1 and main paint 1 is that modified barium sulfate is replaced with unmodified barium sulfate. The infrared spectrum of unmodified barium sulfate is shown below. Figure 1 middle.

[0133] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0134] 2. Application of main coating: Apply the coating of control coating 1 to the substrate pretreated in step 1 using an airless spraying process with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying. Curing time is 8 hours until completely dry, and the dry film thickness is 160 μm.

[0135] Comparative Example 2: Comparative Single-Coat System 2 Including Comparative Coating 2

[0136] The only difference between paint 2 and main paint 1 is that the main paint emulsion is replaced with acrylic emulsion AC-261.

[0137] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0138] 2. Application of main coating: Apply the control coating 2 to the substrate pretreated in step 1 using an airless spraying process with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying. Curing time is 8 hours until completely dry, and the dry film thickness is 160 μm.

[0139] Comparative Example 3: Comparative Single-Coat System 3 Containing Comparative Coating 3

[0140] The only difference between coating 3 and main coating 1 is that nanocellulose is replaced with an equal amount of deionized water.

[0141] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0142] 2. Application of main coating: Apply the coating of contrast coating 3 to the substrate pretreated in step 1 using an airless spraying process with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying. Curing time is 8 hours until completely dry, and the dry film thickness is 160 μm.

[0143] The test results of the obtained single-coat system are shown in Table 7 below:

[0144]

[0145] As can be seen from the test results in Table 7, the single-coat system 1 obtained by the main coating of the present invention is far superior to the comparative single-coat systems of comparative coating 1, comparative coating 2 and comparative coating 3 in terms of stain resistance, aging resistance and scrubbing resistance (strength).

[0146] Example 1': Single-coat system including a main coating 1'

[0147] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0148] 2. Application of the main coating: The main coating 1' prepared in Preparation Example 2' is applied to the substrate pretreated in step 1. An airless spraying process is used with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying. After curing for 8 hours until completely dry, the dry film thickness is 160 μm.

[0149] Example 1”: Single-coat system including main coating 1”

[0150] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0151] 2. Application of the main coating: The main coating 1 prepared in Preparation Example 2” is applied to the substrate pretreated in step 1. An airless spraying process is used with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying. After curing for 8 hours until completely dry, the dry film thickness is 160 μm.

[0152] The test results of the obtained single-coat system are shown in Table 8 below:

[0153] Table 8: Test results of single-coat systems 1' and 1"

[0154] Test Project Example 1' Example 1” Detection methods TSR solar reflectance 94％ 93％ T / CECS10378-2024 hemispherical emissivity 90％ 89％ T / CECS10378-2024 Near-infrared reflectance 88％ 87％ JG / T235-2014 Washability >5000 times >5000 times GB / T 9755-2024

[0155] Example 2: A two-coat system comprising a primer layer and a main coating layer

[0156] 1. Substrate pretreatment: Grind the concrete exterior wall surface smooth, remove floating dust and oil stains, apply one coat of interface agent, and cure for 24 hours.

[0157] 2. Primer application: Apply the primer prepared in Preparation Example 1 to the substrate pretreated in step 1 using an air spraying process with a nozzle diameter of 1.5 mm, a pressure of 0.3 MPa, a wet film thickness of 150 μm, an ambient temperature of 25°C and a humidity of 60%, and dry after curing for 4 hours, with a dry film thickness of 45 μm.

[0158] 3. Application of the main coating: The main coating 1 prepared in Preparation Example 2 is applied to the primer layer obtained in step 2. An airless spraying process is used with a nozzle diameter of 2.0 mm and a pressure of 0.8 MPa. The wet film thickness is 400 μm in one spraying. After curing for 8 hours until completely dry, the dry film thickness is 160 μm.

[0159] The schematic diagram of the obtained double-coating system is in Figure 2 As shown in the image.

[0160] The test results of the obtained double-coating system are shown in Table 9 below:

[0161] Table 9: Test Results of the Two-Coating System

[0162]

[0163] Example 3: A three-coat system comprising a primer layer, a base coat, and a top coat.

[0164] Substrate pretreatment, primer application, and main coating application are performed as described in steps 1-3 of Example 1.

[0165] 4. Topcoat application: Apply the topcoat prepared in Preparation Example 3 onto the main coating obtained in step 3 using a roller coating process. The wet film thickness is 80 μm, and after curing for 3 hours, the dry film thickness is 25 μm.

[0166] The schematic diagram of the obtained three-coating system is shown in Figure 3 As shown in the image.

[0167] The test results of the obtained three-coat system are shown in Table 10 below:

[0168] Table 10: Test Results of the Three-Coating System

[0169]

[0170] As can be seen from the test results in Tables 9 and 10, the double-coating system and triple-coating system of the present invention are far superior to the national standards in terms of stain resistance, aging resistance, and scrubbing resistance (strength).

[0171] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any variations and modifications made by those skilled in the art without departing from the spirit and scope of the invention should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A main coating composition comprising barium sulfate or aluminum oxide modified with organic and inorganic materials, and an aqueous resin as a resin in the main coating emulsion.

2. The main coating composition according to claim 1, comprising 40-85% by weight, preferably 45-80% by weight, more preferably 50-75% by weight, and most preferably 60-70% by weight, of organic and inorganic modified barium sulfate or aluminum oxide, based on the total weight of the main coating composition.

3. The main coating composition according to claim 1 or 2, wherein the particle size of the barium sulfate or alumina modified by the organic and inorganic materials is 0.1-8 μm, preferably 0.2-7 μm, more preferably 0.3-6.5 μm, and most preferably 0.4-6 μm.

4. The main coating composition according to any one of claims 1-3, wherein the inorganic material is silicon dioxide.

5. The main coating composition according to any one of claims 1-4, wherein the amount of the inorganic material is 0.1-5% by weight, preferably 0.2-4.5% by weight, more preferably 0.5-3.5% by weight, and most preferably 0.8-3.2% by weight, based on the total weight of the organic material and the inorganic material modified barium sulfate or alumina.

6. The main coating composition according to any one of claims 1-5, wherein the organic material is selected from fatty acid (salts) such as sodium stearate / calcium, sodium palmitate, silane coupling agents and polymers such as polyacrylates, polyolefins, preferably silane coupling agents.

7. The main coating composition according to any one of claims 1-6, wherein the amount of the organic material is 0.05-2.5 wt%, preferably 0.1-2 wt%, more preferably 0.12-1.5 wt%, and most preferably 0.15-1.2 wt%, based on the total weight of the organic material and the inorganic material modified barium sulfate or alumina.

8. The main coating composition according to any one of claims 1-7, wherein the main coating composition comprises 2-20% by weight, preferably 3-12% by weight, more preferably 4-10% by weight, and most preferably 5-7% by weight of an aqueous resin as the resin in the main coating emulsion, based on the total weight of the main coating composition.

9. The main coating composition according to claim 8, wherein the aqueous resin is selected from inorganic hybrid modified acrylic resin or a combination of inorganic hybrid modified acrylic resin and acrylic resin or fluorocarbon resin.

10. The main coating composition according to claim 9, wherein the hybridization ratio of the inorganic hybrid modified acrylic resin is 5-30% by weight, preferably 7-28% by weight, more preferably 15-25% by weight, and most preferably 18-22% by weight, based on the weight of the inorganic hybrid modified acrylic resin.

11. The main coating composition according to any one of claims 1-10, wherein the main coating composition comprises 0.1-5% by weight, preferably 0.2-2.5% by weight, more preferably 0.5-2% by weight, and most preferably 0.8-1.5% by weight of a dispersant, based on the total weight of the main coating composition.

12. The main coating composition according to any one of claims 1-11, wherein the main coating composition comprises 1-20% by weight, preferably 3-15% by weight, more preferably 5-12% by weight, and most preferably 7-10% by weight of nanocellulose pulp, based on the total weight of the main coating composition.

13. A multi-coat system comprising a primer layer and a main coating layer, wherein the main coating layer is derived from a main coating composition according to any one of claims 1-12.

14. The multi-coating system according to claim 13, wherein the dry film thickness of the main coating is 100-350 μm, preferably 120-330 μm, more preferably 130-320 μm, and most preferably 150-300 μm.

15. The multi-coating system according to claim 13 or 14, wherein the primer layer is derived from a primer composition, wherein the primer composition comprises titanium dioxide, a primer emulsion, and a dispersant.

16. The multi-coating system according to claim 15, wherein the amount of titanium dioxide is 5-30% by weight, preferably 7-28% by weight, more preferably 15-25% by weight, and most preferably 18-22% by weight, based on the total weight of the primer composition.

17. The multi-coating system according to any one of claims 13-16, further comprising a topcoat layer.

18. The multi-coat system of claim 17, wherein the topcoat layer is derived from a topcoat composition comprising a topcoat emulsion and a fluorosilicone additive.

19. The use of organic and inorganic modified barium sulfate or aluminum oxide as defined in any one of claims 3-5 in improving radiative cooling of coating systems.

20. The use according to claim 19, wherein the coating system is a multi-coating system as defined in any one of claims 13-18.

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