Radiation cooling coating and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and provides a radiation refrigeration coating and a preparation method thereof.The radiation refrigeration coating is prepared from, by weight, 5-20 parts of heat reflection filler, 5-20 parts of heat radiation filler, 5-20 parts of common filler, 0.1-0.5 part of a thickening agent, 10-25 parts of aerogel paste, 0.25-0.75 part of a water repellent agent, 0.2-0.5 part of a defoaming agent, 0.3-1.5 parts of a dispersing agent, 0.1-0.3 part of a pH value regulator and 0.3-1 part of a sterilizing, anti-corrosion and anti-mildew agent, 0.1-0.5 part of a wetting agent, 25-40 parts of an acrylic emulsion, 1-2 parts of an anti-freezing agent, 2-4 parts of a coalescing agent and 15-30 parts of water; the functional coating with both high reflection and radiation refrigeration, provided by the invention, is remarkable in reflective insulation / radiation refrigeration effect, non-toxic, odorless, pollution-free and convenient to construct, and is an ideal decorative material.

Description

Technical Field

[0001] The invention relates to the field of polymer coatings, in particular to a coating with high reflection and radiation cooling and a preparation method thereof. Background Art

[0002] The superposition of various background factors such as energy conservation and environmental protection, energy conservation and carbon reduction, ultra-low energy consumption requirements, carbon peak and carbon neutrality, global warming, and climate disasters has led to the demand for environmentally friendly coatings.

[0003] It reflects and radiates most of the energy, suppresses the surface temperature rise caused by direct sunlight, and causes the internal temperature to rise, thereby achieving the effects of heat preservation, heat insulation, energy saving and emission reduction, and cooling. It has excellent thermal insulation performance, decorative properties, outdoor durability and other properties, can effectively reduce the surface temperature of buildings, and is significantly better than ordinary heat reflective coatings.

[0004] CN116640486B discloses a radiation cooling paint for construction and its preparation method, which is prepared from the following components in mass fraction ratio: 5-45 parts of tetrahedral radiation cooling filler, 3-25 parts of titanium dioxide, 2-5 parts of hollow glass microspheres, 15-30 parts of emulsion, 8-10 parts of functional additives, and 20-25 parts of water. The paint uses tetrahedral radiation cooling filler to replace traditional spherical, porous and other particles, forming a multi-directional reflection and radiation surface convex to the base surface on the surface of the topcoat, which can reflect sunlight and ambient refracted light multiple times, increase the radiation surface and convex toward the empty outer space, without infrared radiation shielding, and enhance the radiation cooling efficiency.

[0005] Developing a new type of coating with good thermal insulation and radiation functions through a new technical path is of great significance for energy-saving and carbon-reduction applications in the construction field. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a new technical path and a simple preparation method to realize a coating with high-efficiency reflection and radiation cooling, thereby providing the market with diversified choices for energy-saving and environmentally friendly products.

[0007] In order to solve the above technical problems, the present invention provides a radiation cooling coating and a preparation method thereof. The coating comprises the following components by weight: 5 to 20 parts of heat reflective filler, 5 to 20 parts of heat radiating filler, 5 to 20 parts of common filler, 0.1 to 0.5 parts of thickener, 10 to 25 parts of aerogel paste, 0.25 to 0.75 parts of hydrophobic agent, 0.2 to 0.5 parts of defoaming agent, 0.3 to 1.5 parts of dispersant, 0.1 to 0.3 parts of pH regulator, 0.3 to 1 parts of bactericidal, antiseptic and mildewproof agent, 0.1 to 0.5 parts of wetting agent, 25 to 40 parts of acrylic emulsion, 1 to 2 parts of antifreeze agent, 2 to 4 parts of film-forming aid, and 15 to 30 parts of water.

[0008] The coating with both high reflection and radiation cooling provided by the present invention has remarkable reflection heat insulation / radiation cooling effect, is non-toxic, tasteless, pollution-free, and easy to construct, and is an ideal decorative material. Compared with existing coatings, through the combination of heat-reflective fillers and heat-radiative fillers and the reasonable combination of other materials, it can achieve efficient reflection and radiation of energy of different bands generated by solar radiation, and reduce the surface temperature of the coated object.

[0009] Preferably, the weight proportion of the heat reflective filler is 5 to 20 parts, for example, 5 parts, 8 parts, 10 parts, 15 parts or 20 parts, etc., and Huntsman ALT550 reflective titanium dioxide is preferred.

[0010] Preferably, the weight proportion of the thermal radiation filler is 5 to 20 parts, for example, 5 parts, 8 parts, 10 parts, 15 parts or 20 parts, etc., including any one of metal oxide modified PVDF-HFP nanoparticles, tetrafluoroethylene nanoparticles, silicon-aluminum modified barium sulfate, aerogel materials, aluminum borate, magnesium aluminum titanate or lanthanum zirconate, or a combination of at least two thereof.

[0011] Preferably, the thermal radiation filler is alumina-modified PVDF-HFP nanoparticles.

[0012] The current technology shows that polytetrafluoroethylene nanoparticles have the characteristics of high refractive index and low heat absorption, but no research has shown that they will produce additional effects when used with aerogel products. The present invention finds that due to its high thermal radiation coefficient, it has better heat reflection and heat radiation performance when used with aerogel.

[0013] Alumina modified PVDF-HFP nanoparticles are a high-performance fluoropolymer made from two monomers, polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP), through copolymerization and then modified by metal oxides. The material has high reflectivity in the solar band (about 0.3-2.5 microns), which helps reduce the absorption and heating of sunlight. The interconnected nanosphere structure has a large roughness and high specific surface area, effectively scattering sunlight, including ultraviolet light, visible light and near-infrared light components, thereby achieving high reflectivity; in the infrared radiation window of the atmosphere (8-13 microns), it can effectively radiate heat to the universe, with a high emissivity, achieving cooling without electricity during the day. Reasonable combination of materials such as aerogel and specific preparation methods have significant comprehensive effects, with a solar reflectance of more than 0.94, a hemispherical emissivity of more than 0.93, and an atmospheric window emissivity of 0.98. Stability and durability: Stability and durability enable the coating to maintain excellent radiant cooling performance in outdoor environments even after long periods of rain and sunlight exposure.

[0014] At present, alumina-modified PVDF-HFP nanoparticles are mainly used in the field of lithium-ion batteries and are one of the key materials for diaphragms. They have not yet been used in the field of coatings. The present invention unexpectedly found that alumina-modified PVDF-HFP nanoparticles have a good radiation cooling effect. Combined with heat-reflective fillers and other materials in the coating, the radiation cooling effect can be further exerted to promote the radiation cooling performance of the coating. The micro-nano fiber structure of PVDF-HFP nanoparticles can effectively scatter sunlight. This is due to the Mie scattering effect, that is, the ratio of the particle diameter to the wavelength of light is proportional. The PVDF-HFP molecular bond has a high infrared emissivity in the 8-13μm band; and alumina itself is also highly reflective. It is used to modify PVDF-HFP nanoparticles. After the nanoparticles are modified, the extinction coefficient in the sunlight band can be ignored, and there are multiple extinction peaks in the long infrared band. While maintaining high reflectivity, it also helps to radiate heat outward through the atmospheric window to reduce the temperature. PVDF-HFP nanoparticles modified with alumina promote and enhance the radiation cooling effect.

[0015] By preparing radiation cooling coatings, the energy of different bands generated by sunlight can be scattered more effectively, while reducing the solar energy absorption rate and increasing the reflectivity and thermal emissivity of sunlight, thereby achieving a radiation cooling effect.

[0016] In addition, the high-purity fine silicon-aluminum modified barium sulfate and aerogel materials used in the present invention also have good technical effects.

[0017] Compared with ordinary barium sulfate, high-purity fine silicon-aluminum modified barium sulfate has high chemical stability and is not easy to stratify. It has a high reflectivity from ultraviolet light to infrared light, that is, the reflective performance covers a wider wavelength range. It can be used to replace traditional calcium carbonate as a filler. Through special processes or material treatment, it can be evenly "dissolved" in water and is not easily affected by environmental factors. Therefore, the optical properties can remain stable during long-term use, which can improve the reflection and radiation stability of the coating and reduce the intensity of the absorption band, which can reach more than 94% in total.

[0018] There are many types of aerogel materials, and the aerogel paste used in the present invention is preferably made of silica aerogel. The pore size of silica aerogel is between 20nm and 50nm, and the size of air molecules is about 70nm, which is larger than the diameter of the pores of silica aerogel; the refractive index of silica aerogel is close to 1, and the ratio of the annihilation coefficient of infrared and visible light is more than 100. It can effectively transmit the visible light part of sunlight and block the infrared light part, and has a good effect on the reflection and heat insulation (blocking) of sunlight energy, which can improve the comprehensive performance of the coating. Silica aerogel itself has a high specific heat capacity, and the thermal radiation transfer can be minimized, so it has good thermal insulation performance. Specifically, the thermal insulation effect of aerogel is 2 to 5 times that of traditional thermal insulation materials.

[0019] Preferably, the weight of the common filler is 5 to 20 parts, for example, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts, etc. The common filler is high-purity fine silicon-aluminum modified barium sulfate.

[0020] Preferably, the weight portion of the thickener is 0.1 to 0.5 parts, for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts or 0.5 parts, etc., including any one of hydroxyethyl cellulose, alkali swelling thickener, polyurethane thickener or hydroxymethyl cellulose.

[0021] Preferably, the weight proportion of the aerogel paste is 10 to 25 parts, for example, 10 parts, 15 parts or 20 parts.

[0022] Preferably, the weight portion of the hydrophobic agent is 0.25 to 0.75 parts, for example, it can be 0.25 parts, 0.3 parts, 0.4 parts, 0.5 parts or 0.75 parts.

[0023] Preferably, the weight portion of the defoamer is 0.2 to 0.5 parts, for example, 0.2 parts, 0.3 parts, 0.4 parts or 0.5 parts, etc. Defoamers can generally be selected from: silicones, polyethers, mineral oils, etc.

[0024] Preferably, the weight portion of the dispersant is 0.3 to 1.5 parts, for example, it can be 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part or 1.5 parts, etc., including any one of Nopco SN-5027, Dow CA-2500 or Gotek P90.

[0025] Preferably, the dispersant is Nopco SN-5027.

[0026] Preferably, the weight portion of the pH adjuster is 0.1 to 0.3 parts, for example, 0.1 parts, 0.2 parts or 0.3 parts, etc. The pH adjuster can generally be selected from: AMP-95 (2-amino-2-methyl-1-propanol), NaOH, NaHCO3, ammonia water, etc. 2-amino-2-methyl-1-propanol is preferred.

[0027] Preferably, the weight portion of the bactericidal, antiseptic and mildew-proof agent is 0.3 to 1 part, for example, 0.3, 0.5, 0.8 or 1 part, etc. The bactericidal, antiseptic and mildew-proof agent can generally be: Lanxess Preventol BIT20D or Taiwan BEK BEK-550, etc.

[0028] Preferably, the weight portion of the wetting agent is 0.1 to 0.5 parts, for example, 0.1 parts, 0.2 parts, 0.4 parts or 0.5 parts, etc., including any one of Dow BD-109, BASF E9289 or Clariant LCN070.

[0029] Preferably, the wetting agent is Dow BD-109.

[0030] Preferably, the weight proportion of the acrylic emulsion is 25 to 40 parts, for example, 25 parts, 30 parts, 35 parts or 40 parts.

[0031] Preferably, the weight portion of the antifreeze agent is 1 to 2 parts, for example, 1 part, 1.5 parts or 2 parts, etc. The antifreeze agent generally uses antifreeze agents such as ethylene glycol commonly used in the art.

[0032] Preferably, the weight portion of the film-forming aid is 2 to 4 parts, for example, 2 parts, 3 parts or 4 parts.

[0033] Preferably, the thickener is hydroxyethyl cellulose.

[0034] Preferably, the weight portion of water is 15 to 30 parts, for example, 15 parts, 20 parts, 25 parts or 30 parts.

[0035] The implementation of the present invention has the following beneficial effects:

[0036] High reflectivity and radiation cooling. Currently, white paint usually reflects about 85% of the incident solar radiation, and the rest is absorbed by the coating. This coating can bring a significant leap forward, reflecting most of the sunlight, while having a high infrared emissivity in the atmospheric window (8-13 microns), radiating heat in the form of infrared rays, thereby reducing the surface temperature of the object, that is, radiation cooling. This coating can achieve a cooling effect without consuming energy, which is of great significance for reducing air conditioning power consumption and reducing energy consumption.

[0037] Self-cleaning function: After film formation, the coating has hydrophobic properties, making it difficult for dust and pollutants in the air to adhere. Even if they adhere to it, they can be easily washed away by rainwater, reducing maintenance costs.

[0038] High Outdoor Durability: Compared with ordinary acrylic paint, it has better outdoor durability.

[0039] Decorative: Decorate and protect buildings, effectively reduce the temperature of objects and extend the service life of buildings.

[0040] Easy construction: The construction method is simple and convenient. It can be sprayed, rolled or brushed without causing damage to the building. DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0043] Example 1

[0044] This example provides a radiation cooling coating and a preparation method thereof

[0045] 15 parts of heat-reflective filler ALT550, 20 parts of alumina-modified PVDF-HFP nanoparticles, 15 parts of high-purity fine silicon-aluminum-modified barium sulfate, 0.1 parts of hydroxyethyl cellulose, 20 parts of aerogel paste, 0.5 parts of silicone hydrophobic agent, 0.5 parts of Nopco NXZ, 1.2 parts of Nopco SN-5027, 0.1 parts of 2-amino-2-methyl-1-propanol, 0.8 parts of Lanxess Preventoi BIT20D, 0.3 parts of BD-109, 25 parts of acrylic emulsion, 1.2 parts of ethylene glycol, 2 parts of alcohol ester, and 15 parts of water.

[0046] Preparation method: firstly, water is added in parts by weight into a clean dispersion kettle, and a thickener, a dispersant, a wetting agent, a pH regulator and a part of a defoaming agent are added in parts by weight in sequence under stirring, and the mixture is dispersed at a medium speed for about 5 minutes; heat-reflecting fillers, common fillers and the like are added in parts by weight in sequence, and the mixture is dispersed at a high speed for about 20 minutes, and the fineness is tested. After the fineness is qualified, heat-radiating fillers and aerogel paste are added and dispersed evenly to obtain a semi-finished product slurry; the semi-finished product slurry is transferred to a paint mixing kettle, and acrylic emulsion, a defoaming agent, ethylene glycol, alcohol ester twelve, an organosilicon hydrophobic agent, a bactericidal, antiseptic and mildew-proof agent and the like are added in sequence, and the radiation cooling coating of the present invention is obtained after being fully stirred evenly.

[0047] Example 2

[0048] This example provides a radiation cooling coating and a preparation method thereof

[0049] 15 parts of heat-reflective filler ALT550, 20 parts of alumina-modified PVDF-HFP nanoparticles, 15 parts of high-purity fine silicon-aluminum-modified barium sulfate as ordinary filler, 0.1 parts of hydroxyethyl cellulose, 20 parts of aerogel paste, 0.5 parts of silicone hydrophobic agent, 0.5 parts of Nopco NXZ, 0.1 parts of Nopco SN-5027, 0.1 parts of 2-amino-2-methyl-1-propanol, 0.8 parts of Lanxess Preventol BIT20D, 0.3 parts of BD-109, 25 parts of acrylic emulsion, 1.2 parts of ethylene glycol, 2 parts of alcohol ester twelve, and 15 parts of water.

[0050] The preparation process is consistent with that in Example 1.

[0051] Example 3

[0052] This example provides a radiation cooling coating and a preparation method thereof

[0053] 15 parts of heat-reflective filler ALT550, 5 parts of alumina-modified PVDF-HFP nanoparticles, 15 parts of high-purity fine silicon-aluminum-modified barium sulfate as ordinary filler, 0.1 parts of hydroxyethyl cellulose, 20 parts of aerogel paste, 0.5 parts of silicone hydrophobic agent, 0.5 parts of Nopco NXZ, 1.2 parts of Nopco SN-5027, 0.1 parts of 2-amino-2-methyl-1-propanol, 0.8 parts of Lanxess Preventol BIT20D, 0.3 parts of BD-109, 25 parts of acrylic emulsion, 1.2 parts of ethylene glycol, 2 parts of alcohol ester twelve, and 15 parts of water.

[0054] The preparation process is consistent with that in Example 1.

[0055] Example 4

[0056] This example provides a radiation cooling coating and a preparation method thereof

[0057] 5 parts of heat-reflective filler ALT550, 20 parts of alumina-modified PVDF-HFP nanoparticles, 15 parts of high-purity fine silicon-aluminum-modified barium sulfate, 0.1 parts of hydroxyethyl cellulose, 20 parts of aerogel paste, 0.5 parts of silicone hydrophobic agent, 0.5 parts of Nopco NXZ, 1.2 parts of Nopco SN-5027, 0.1 parts of 2-amino-2-methyl-1-propanol, 0.8 parts of Lanxess Preventol BIT20D, 0.3 parts of BD-109, 25 parts of acrylic emulsion, 1.2 parts of ethylene glycol, 2 parts of alcohol ester twelve, and 15 parts of water.

[0058] The preparation process is consistent with that in Example 1.

[0059] Example 5

[0060] This example provides a radiation cooling coating and a preparation method thereof

[0061] 15 parts of heat-reflective filler ALT550, 20 parts of alumina-modified PVDF-HFP nanoparticles, 5 parts of high-purity fine silicon-aluminum-modified barium sulfate as ordinary filler, 0.1 parts of hydroxyethyl cellulose, 20 parts of aerogel paste, 0.5 parts of silicone hydrophobic agent, 0.5 parts of Nopco NXZ, 1.2 parts of Nopco SN-5027, 0.1 parts of 2-amino-2-methyl-1-propanol, 0.8 parts of Lanxess Preventol BIT20D, 0.3 parts of BD-109, 25 parts of acrylic emulsion, 1.2 parts of ethylene glycol, 2 parts of alcohol ester twelve, and 15 parts of water.

[0062] The preparation process is consistent with that in Example 1.

[0063] Example 6

[0064] This example provides a radiation cooling coating and a preparation method thereof

[0065] 5 parts of heat-reflective filler ALT550, 20 parts of alumina-modified PVDF-HFP nanoparticles, 10 parts of high-purity fine silicon-aluminum-modified barium sulfate, 0.1 parts of hydroxyethyl cellulose, 20 parts of aerogel paste, 0.75 parts of silicone hydrophobic agent, 0.5 parts of Nopco NXZ, 1.2 parts of Nopco SN-5027, 0.1 parts of 2-amino-2-methyl-1-propanol, 0.3 parts of Lanxess Preventol BIT20D, 0.3 parts of BD-109, 25 parts of acrylic emulsion, 2 parts of ethylene glycol, 4 parts of alcohol ester, and 15 parts of water.

[0066] The preparation process is consistent with that in Example 1.

[0067] Example 7

[0068] This example provides a radiation cooling coating

[0069] 20 parts of heat-reflective filler ALT550, 5 parts of alumina-modified PVDF-HFP nanoparticles, 10 parts of high-purity fine silicon-aluminum-modified barium sulfate as ordinary filler, 0.4 parts of hydroxyethyl cellulose, 10 parts of aerogel paste, 0.25 parts of silicone hydrophobic agent, 0.2 parts of Nopco NXZ, 0.3 parts of Nopco SN-5027, 0.3 parts of 2-amino-2-methyl-1-propanol, 1 part of Lanxess Preventol BIT20D, 0.5 parts of BD-109, 40 parts of acrylic emulsion, 1 part of ethylene glycol, 2 parts of alcohol ester twelve, and 30 parts of water.

[0070] The preparation process is consistent with that in Example 1.

[0071] Example 8

[0072] This comparative example is substantially the same as Example 1, except that in this comparative example, the alumina-modified PVDF-HFP nanoparticles are replaced with polytetrafluoroethylene nanoparticles.

[0073] Example 9

[0074] This comparative example is substantially the same as Example 1, except that in this comparative example, the alumina-modified PVDF-HFP nanoparticles are replaced with lanthanum zirconate.

[0075] Comparative Example 1

[0076] This comparative example is substantially the same as Example 1, except that this comparative example does not include an aerogel paste.

[0077] Comparative Example 2

[0078] This comparative example is substantially the same as Example 1, except that the weight portion of the acrylic emulsion in this comparative example is 10 parts.

[0079] Comparative Example 3

[0080] This comparative example is substantially the same as Example 1, except that ethylene glycol is not included in this comparative example.

[0081] Comparative Example 4

[0082] This comparative example is substantially the same as Example 1, except that this comparative example does not include ALT550.

[0083] Comparative Example 5

[0084] This comparative example is substantially the same as Example 1, except that this comparative example does not include alumina-modified PVDF-HFP nanoparticles.

[0085] The products of the embodiments of the present invention and the comparative examples were subjected to performance tests.

[0086] The solar reflectance, near-infrared reflectance, hemispherical emissivity, atmospheric window emissivity, and thermal insulation temperature compared with the reference black and white are tested in accordance with GB / T25261 and T / CECS10378 standards, and the other basic properties are tested in accordance with GB / T 9755. The specific results are shown in Tables 1, 2, 3, and 4 below:

[0087] Table 1

[0088]

[0089] Table 2

[0090]

[0091]

[0092] Table 3

[0093]

[0094] Table 4

[0095]

[0096]

[0097] From the data in Table 1, it can be seen that the radiation cooling coating provided by the present invention achieves more than 94% of the incident solar radiation by using alumina-modified PVDF-HFP nanoparticles, heat-reflecting fillers and aerogels. The thermal insulation temperature difference with the reference blackboard can reach about 28°C, and the radiation cooling effect is significant. However, when the components such as alumina-modified PVDF-HFP nanoparticles and ALT550 are changed, the effect is significantly reduced.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A radiation cooling paint, characterized in that: The coating comprises the following components by weight: 5-20 parts of heat reflective filler, 5-20 parts of heat radiating filler, 5-20 parts of common filler, 0.1-0.5 parts of thickener, 10-25 parts of aerogel paste, 0.25-0.75 parts of hydrophobic agent, 0.2-0.5 parts of defoaming agent, 0.3-1.5 parts of dispersant, 0.1-0.3 parts of pH regulator, 0.3-1 parts of bactericidal, preservative and mildewproof agent, 0.1-0.5 parts of wetting agent, 25-40 parts of acrylic emulsion, 1-2 parts of antifreeze agent, 2-4 parts of film-forming aid and 15-30 parts of water.

2. The coating according to claim 1, characterized in that The heat reflective filler is Huntsman ALT550 reflective titanium dioxide.

3. The coating according to claim 1, characterized in that The thermal radiation filler includes any one of alumina-modified PVDF-HFP nanoparticles, polytetrafluoroethylene nanoparticles, aerogel materials, aluminum borate, magnesium aluminum titanate, or lanthanum zirconate, or a combination of at least two thereof.

4. The coating according to claim 3, characterized in that The thermal radiation filler is alumina-modified PVDF-HFP nanoparticles.

5. The coating according to claim 1, characterized in that The dispersant includes any one of Nopco SN-5027, Dow CA-2500 or Gotai P90.

6. The coating according to claim 5, characterized in that The dispersant is Nopco SN-5027.

7. The coating according to claim 1, characterized in that The wetting agent includes any one of Dow BD-109, BASF E9289 or Clariant LCN070.

8. The coating according to claim 7, characterized in that The wetting agent is Dow BD-109.

9. The coating according to claim 1, characterized in that The thickener includes any one of hydroxyethyl cellulose, alkali swelling thickener, polyurethane thickener or hydroxymethyl cellulose.

10. The coating according to claim 9, characterized in that The thickener is hydroxyethyl cellulose.

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