Multifunctional water-based low-temperature paint double-coating structure, multifunctional water-based low-temperature paint coating system and application

Abstract

The invention relates to a multifunctional water-based low-temperature paint double-coating structure which comprises a first coating and a second coating, the first coating comprises a metal sheet pigment and inorganic oxide pigment mixture, and the second coating comprises transparent organic color paste. A first coating paint composition used for the first coating and a second coating paint composition used for the second coating are both mixtures containing acrylic resin emulsion and polyurethane dispersoid. The double-coating structure adopts the technical scheme of mixed pigment, curing agents such as isocyanate are not contained, and the obtained double-coating structure has high radar wave transmission performance, high infrared reflection performance and high reflection and heat insulation capacity, is particularly suitable for black or silver coating systems, adopts water-based low-temperature coating, and has the advantages that the water-based low-temperature coating is adopted, so that the water-based low-temperature coating is more environment-friendly; the paint has the characteristics of remarkable low-temperature quick-drying film formation, thin coating and low VOC (volatile organic compound), and can realize low energy consumption, health and environmental protection of a coating process. The invention further comprises a multifunctional water-based low-temperature paint coating system and application.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic wave functional coatings, and in particular to a water-based low-temperature coating double-coating structure capable of achieving multiple functions such as high radar wave transmittance and high infrared reflection, as well as a multifunctional water-based low-temperature coating system and application. Background Art

[0002] With the rapid development of emerging fields such as autonomous driving and low-altitude flight, aircraft, automobiles, smart devices and other fields have higher requirements for surface coatings. For example, they hope to achieve high radar wave transmission while having high infrared reflection and heat insulation performance, so as to enhance the safety of equipment, reduce equipment energy loss and improve riding comfort. Therefore, coatings with radar wave transmission function, functional coatings that enhance laser radar infrared reflection signals, and functional coatings that reflect and insulate are receiving more and more attention.

[0003] However, since the most popular coatings such as black and silver often require the addition of black pigments or aluminum effect pigments when achieving metallic texture and color depth, this will result in a large amount of infrared light absorption, making it difficult to identify lidar signals and a significant increase in surface temperature, or it will not be able to penetrate radar waves and other signals, affecting the signal transmission between the internal space of the device and the outside.

[0004] In the prior art, patent CN115873459A discloses a coating system with a high reflection intensity for laser signals, which can still have a high reflection intensity for laser radar signals when the incident angle gradually increases; patent CN116410628A discloses a coating system with a multilayer structure, which has strong near-infrared reflection performance and has stronger reflection performance for detection signals using near-infrared bands; patent CN116162363A discloses a radar frequency transparent effect pigment mixture, and the coating formed by it can achieve an increase in radar transmittance. However, as can be seen from the above, the known related technologies are coatings that only have a single function of high radar wave transmission, high infrared reflection, and high reflection and heat insulation performance. There are defects in realizing multifunctional uses and cannot meet the requirements in practical applications. At the same time, some technologies also need to increase the thickness of the primer layer, and the application effect of some technologies on some substrates (such as carbon fiber, etc.) will be greatly reduced.

[0005] In summary, the art urgently needs to develop a water-based low-temperature coating double-coating structure that can simultaneously have functions such as high radar wave transmittance, high infrared reflection, and high reflective heat insulation performance to solve the problems existing in the prior art. Summary of the invention

[0006] Based on the above facts, the object of the present invention is to provide a multifunctional water-based low-temperature paint double coating structure, and a multifunctional water-based low-temperature paint coating system using the double coating structure. The multifunctional water-based low-temperature paint double coating structure adopts a technical solution of mixed pigments, does not contain curing agents such as isocyanates, amino resins, and polyamine resins, and the resulting double coating structure has high radar wave transmission performance, high infrared reflection performance, and high reflection and heat insulation capabilities. The infrared reflectivity (780-2500nm) is greater than 60%, and the radar wave transmission loss increase value is <0.5dB, which is particularly suitable for black or silver type coating systems. In addition, the double coating structure of the present invention adopts water-based low-temperature paint, which has significant low-temperature quick-drying film-forming, thin coating and low VOC characteristics, and can achieve low energy consumption, health and environmental protection in the coating process.

[0007] The first aspect of the present invention provides a multifunctional water-based low-temperature paint double-coating structure, including a first coating and a second coating, wherein the first coating comprises a mixture of metal flake pigments and inorganic oxide pigments, and the second coating comprises a transparent organic color paste, and the first coating coating composition used for the first coating and the second coating coating composition used for the second coating are both mixtures comprising an acrylic resin emulsion and a polyurethane dispersion.

[0008] First coating composition

[0009] In some embodiments of the present invention, the first coating composition comprises, by weight percentage:

[0010]

[0011] The total content of the above components is 100%.

[0012] Preferably, the amount of the metal flake pigment dispersion is 1-3 wt %, more preferably 1-2 wt %.

[0013] Second coating composition

[0014] In some embodiments of the present invention, the second coating composition comprises, by weight percentage:

[0015]

[0016] The total content of the above components is 100%.

[0017] Acrylic resin emulsion

[0018] In the present invention, the acrylic resin emulsions contained in the first coating composition and the second coating composition are selected from self-crosslinking or low-hydroxyl content resins, which are basically transparent in the near-infrared range of 780nm-2500nm, have little effect on the reflectivity or transmittance of infrared, and do not need to add a curing agent. Preferably, the acrylic resin emulsion is selected from one or more of water-based acrylic emulsions, polyester-modified acrylic emulsions, or polyurethane-modified acrylic emulsions with a hydroxyl content of 0-3%, a solid content of 20-50%, a glass transition temperature (Tg)>25°C, and a minimum film-forming temperature (MFTT)>25°C. The acrylic resin emulsion and the polyurethane dispersion are mixed and used in a suitable ratio to show better adhesion, flexibility and film-forming effect.

[0019] Specifically, the acrylic resin emulsion is selected from one or more of the acrylic resin emulsions of SETAQUA@6801 and SETAQUA@6802 provided by Allnex Resins, Bayhydrol@A2846, Bayhydrol@A2474, Bayhydrol@A2457, Bayhydrol@A2856xp, and Bayhydrol@A2469 provided by Covestro Resins, WD-594 and WD-588 provided by DIC Resins, and Joncryl@8330AP, Joncryl@8111AP, Joncryl@HYB 6336, Joncryl@HYB 6340, and Joncryl@HYB 6345AP provided by BASF Resins.

[0020] Polyurethane dispersion

[0021] In the present invention, the polyurethane dispersions contained in the first coating composition and the second coating composition are selected from one or more of waterborne polyurethane dispersions, acrylic modified polyurethane dispersions, aliphatic modified polyurethane dispersions, and polyester modified polyurethane dispersions that do not contain hydroxyl groups, have a solid content of 20-50%, a glass transition temperature (Tg) <0°C, and a minimum film forming temperature (MFTT) <5°C. The acrylic resin emulsion and the polyurethane dispersion are mixed and used in a suitable ratio to show better adhesion, flexibility, and film-forming effects.

[0022] Specifically, the polyurethane dispersion is selected from one or more of the polyurethane dispersions of Joncryl@U 4190, Joncryl@U5168, and Joncryl@U 4199AP provided by BASF, WATERSOL UD-5002 and WATERSOL UD-8801 provided by DIC Resins, Bayhydrol@UH2648, Bayhydrol@UH2648 / 1, Bayhydrol@UH2606, Bayhydrol@UH2952, and Bayhydrol@UA2856 provided by Covestro, and DAOTAN VTW6460, DAOTAN VTW6462, and DAOTAN VTW6464 provided by Allnex Resins.

[0023] Metallic flake pigment dispersion

[0024] In the present invention, the metal flake pigment dispersion comprises, by weight:

[0025] 3-15 parts of deionized water;

[0026] Dispersant 0.1-1 part;

[0027] 2-8 parts of metal flake pigment;

[0028] The metal flake pigment is selected from one or more of silver dollar aluminum pigment, corn flake aluminum pigment, electroplated silver aluminum pigment, copper pigment, and alloy flake pigment, and has a particle size of 5-50 μm and a thickness of 10-500 nm. The metal flake pigment has excellent hiding power and good infrared reflection ability. Although the metal pigment with good conductivity will also cause loss to radar waves, the loss can be reduced to a lower level through the design of the present invention.

[0029] In some preferred embodiments of the present invention, the metal flake pigment is a metal flake pigment with a surface coated with a modified resin or a silica modified layer; more preferably, the metal flake pigment is a silica-coated flaky aluminum silver paste.

[0030] Specifically, the aluminum paste includes but is not limited to one or more of the STAPAHYDROLAN series 2153, 2154, 2156, 2197, 2192, S422 provided by Aika Company, HYDROSHINE WS series 3001, 3004, METALURE series 1006, SBC AQ J series 6713, 6718, 6812, 6834 provided by Starlink Company, and ZW6120, ZW6113, ZW6130 and other models of aluminum paste provided by Zuxing Company.

[0031] Inorganic oxide color paste

[0032] In the present invention, the inorganic oxide color paste comprises, by weight:

[0033]

[0034]

[0035] The inorganic oxide flake pigment is a special pigment with high brightness and an angularly variable color effect. The size of the pigment can be adjusted according to product requirements to achieve different brightness, hiding power and angularly variable color effects.

[0036] In some embodiments of the present invention, the inorganic oxide flake pigment is selected from one or more of mica flakes, synthetic mica flakes, alumina flakes, and glass flakes, and the particle size of the inorganic oxide flake pigment is 5-50 μm and the thickness is 10-1000 nm. Preferably, the inorganic oxide flake pigment is an inorganic oxide flake pigment whose surface is coated with silicon dioxide, titanium dioxide, iron oxide, iron titanium oxide or iron manganese oxide, and the white powder filler is selected from one or more of titanium dioxide, barium sulfate, calcium carbonate, talc, and wollastonite, and the particle size of the white powder filler is 0.1-50 μm.

[0037] Specifically, the inorganic oxide flake pigments include but are not limited to one or more of the inorganic oxide flake pigments such as SM015, SM525, and SM025 provided by Kuncai Technology, 9602, 9605, 9612, 9121, and 9119 of the iriodin series provided by Merck, T61-10WNT microsilver and T60-10WNT crystalsilver of the xirallic series, OEM OPAQUESILVER and OEM silver series provided by Aika; the white powder filler is selected from one or more of the titanium dioxide models Tipaque CR-97, Tipaque FR404, and Tipaque R930 provided by Ishihara of Japan.

[0038] Transparent organic color paste

[0039] In the present invention, the transparent organic color paste includes one or more dispersions of different colors, and the dispersions include, by weight:

[0040]

[0041] The preparation step of the dispersion comprises: mixing deionized water, a dispersant, a dispersing resin and a pigment for 30 minutes, adjusting the pH to 7.5-8.5 with a pH adjuster, and then sand-milling for 1-3 hours until the fineness is less than 10 μm, so as to obtain the dispersion; the pigment is selected from one or more of red pigment, yellow pigment, blue pigment and black pigment, including but not limited to one or more of indanthrone, copper phthalocyanine blue pigment, YInMn indium manganese blue, perylene black pigment, perylene red pigment, non-hiding DPP red pigment, quinacridone red pigment, quinophthalone pigment, isoindolinone pigment and benzimidazolone based yellow-orange pigment.

[0042] Specifically, the red pigment is selected from one or more of the red pigments of the models Paliogen@RedL3850, Paliogen@Red L3875, Paliogen@Red L3885, and Paliogen@Red L4045 provided by BASF of Germany; the yellow pigment is selected from one or more of the yellow pigments of the models Paliotol@Yellow L0962, Paliotol@Yellow L0960, Paliotol@Yellow L1155, Sicopal@Yellow L1130, Sicopal@Yellow L1100, and Sicopal@Yellow L1635 provided by BASF of Germany; the blue pigment is selected from one or more of the blue pigments of the models Heliogen@Blue L7085, Heliogen@Blue L6975, Heliogen@BlueL6930 and Heliogen@Blue L7081 provided by BASF of Germany; the black pigment is selected from one or more of the blue pigments of the models Paliogen@Black L7085, ... The dispersing resin is selected from SETAL@6303 resin of Allnex, Joncryl@62J of BASF, ACW-1011 of Nippon Paint, preferably SETAL@6303 resin of Allnex. The dispersing agent is selected from one or more of the dispersing agents of the models 190, 192, 180, 2012, 2014 provided by BYK, and the Dispex series ULTRAPX 4550, 4522, 4525, 4575 provided by BASF.

[0043] Wetting and leveling agent

[0044] In some embodiments of the present invention, the wetting and leveling agent is selected from one or more of the wetting and leveling agents of models 347, 349, 3451, 381, 3560, and 3455 provided by BYK and the hydropalat@WE series 3179, 3189, 3220, 3225, and 3229 provided by BASF.

[0045] Defoaming agent

[0046] In some embodiments of the present invention, the defoaming agent is selected from one or more of the defoaming agents of models 011, 024, 015, 028, 1710 provided by BYK, and SI2281, SI2210, and SI2299 of the Foamaster series provided by BASF.

[0047] Thickener

[0048] In some embodiments of the present invention, the thickener is selected from one or more of the thickeners of AQUATIX 8421, LAPONITE-RD, RHEOBYK-440, RHEOBYK-7420 provided by BYK, and Rheovis series HS1212, HS1303, AS1130, AS1189, PU1235, and PU1250 provided by BASF. Among them, LAPONITE-RD is pre-dispersed into a 3% aqueous solution for use.

[0049] pH Adjusters

[0050] In some embodiments of the present invention, the pH adjuster is a 10% dimethylethanolamine solution (DMEA).

[0051] Solvents

[0052] In some embodiments of the present invention, the solvent is mainly deionized water, and a film-forming solvent having a mass percentage of not more than 10% may also be added. The film-forming solvent is selected from one or more of isooctyl alcohol, isopropanol, propylene glycol, propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, diethylene glycol butyl ether, and dipropylene glycol butyl ether.

[0053] The second aspect of the present invention provides a multifunctional water-based low-temperature paint coating system, comprising a varnish layer, a second coating layer, a first coating layer and a primer layer; the varnish used in the varnish layer is an isocyanate-cured hydroxyl acrylic resin composition; the primer used in the primer layer is a high-solid isocyanate-cured polyamine resin two-component coating composition; the first coating layer comprises a mixture of metal flake pigments and inorganic oxide pigments, the second coating layer comprises a transparent organic color paste, and the first coating layer coating composition used in the first coating layer and the second coating layer coating composition used in the second coating layer are both mixtures comprising an acrylic resin emulsion and a polyurethane dispersion.

[0054] Varnish

[0055] In the present invention, the viscosity of the varnish is in the range of 100-5000 mPa·s, and the varnish is preferably Nippon varnish C7900 provided by Nippon Paint Corporation.

[0056] Primer

[0057] In the present invention, the solid content of the primer is greater than 70%, and the viscosity ranges from 100 to 20000 mPa·s; preferably, the primer is Nippon paint P7001 provided by Nippon Paint Corporation.

[0058] The third aspect of the present invention provides a method for preparing the multifunctional water-based low-temperature coating system according to the second aspect of the present invention, comprising the following steps:

[0059] S1: Preparation of the first coating composition:

[0060] Open the stirring kettle, add the solvent, acrylic resin emulsion, polyurethane dispersion, metal flake pigment, inorganic oxide color paste, transparent organic color paste, wetting and leveling agent, defoaming agent, and thickener into the stirring kettle in sequence, and stir until fully mixed; adjust the pH to 7.5-8.5 with a pH adjuster to obtain the first coating composition;

[0061] S2: Preparation of the second coating composition:

[0062] Open the stirring kettle, add the solvent, acrylic resin emulsion, polyurethane dispersion, transparent organic color paste, wetting and leveling agent, defoaming agent, and thickener into the stirring kettle in sequence, and stir until fully mixed; adjust the pH to 7.5-8.5 with a pH adjuster to obtain the second coating composition;

[0063] S3: Spraying:

[0064] The first coating composition is sprayed on the surface of the primer layer, and flash-dried at 60-80°C for 5-10 minutes to obtain a first coating; the second coating composition is continuously sprayed on the surface of the first coating, and dried at 60-80°C for 10-30 minutes to obtain a second coating; and clear varnish is sprayed on the surface of the second coating, and cured at 60-100°C for 30-120 minutes to form a clear varnish layer, thereby obtaining the multifunctional water-based low-temperature coating system.

[0065] The fourth aspect of the present invention provides applications of the multifunctional water-based low-temperature paint coating system described in the second aspect of the present invention, including applications in the fields of aircraft, automobiles, and smart devices.

[0066] Beneficial Effects of the Invention

[0067] The present invention provides a multifunctional water-based low-temperature coating double coating structure, which adopts a technical solution of mixed pigments, does not contain curing agents such as isocyanates, amino resins, and polyamine resins, and the obtained double coating structure has high radar wave transmission performance, high infrared reflection performance, and high reflection and heat insulation capabilities. The infrared reflectivity (780-2500nm) is greater than 60%, and the radar wave transmission loss increase value is <0.5dB, which is particularly suitable for black or silver type coating systems. In addition, the double coating structure of the present invention adopts water-based low-temperature coatings, which has significant low-temperature quick-drying film-forming, thin coatings and low VOC characteristics, and can achieve low energy consumption, health and environmental protection of the coating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a schematic diagram of the double-coating structure of the multifunctional water-based low-temperature coating of the present invention.

[0069] Figure 2 This is a schematic diagram of the structure of the multifunctional water-based low-temperature paint coating system of the present invention coated on a substrate.

[0070] The numbers in the figure represent: 1. varnish layer; 2. second coating layer; 3. first coating layer; 4. primer layer; 5. substrate. DETAILED DESCRIPTION

[0071] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with specific examples and comparative examples. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention. The experimental methods used in the following examples and comparative examples are conventional methods unless otherwise specified, and the raw materials and reagents used are products that can be purchased from conventional commercial channels unless otherwise specified.

[0072] The above technical solution is described below in conjunction with specific embodiments.

[0073] Preparation of Metallic Flake Pigment Dispersion

[0074] STAPAHYDROLAN 2192, HYDROSHINE WS 3001, ZW6120, and SBC AQ J6713 aluminum pastes were selected respectively, and 5 parts of deionized water, 0.5 parts of BYK192, and 5 parts of aluminum pastes were stirred and mixed at a low speed and allowed to stand for 2 hours to prepare STAPAHYDROLAN 2192 dispersion, HYDROSHINE WS 3001 dispersion, ZW6120 dispersion, and SBC AQ J6713 dispersion, respectively.

[0075] Preparation of Inorganic Oxide Color Paste

[0076] SM015, iriodin 9612, OEM OPAQUE SILVER, and iriodin 9119 inorganic oxide flake pigments were selected respectively, and 5 parts of deionized water, 0.5 parts of BYK190, and 5 parts of inorganic oxide flake pigments were stirred and mixed evenly at a low speed, and allowed to stand for 2 hours for use, to prepare SM015 color paste, iriodin 9612 color paste, OEM OPAQUE SILVER color paste, and iriodin9119 color paste respectively.

[0077] Preparation of a first coating composition free of transparent organic colorants

[0078] First coating composition samples 1-11 without transparent organic colorant were prepared according to Table 1 below.

[0079] Table 1 Sample 1-11 formula

[0080]

[0081]

[0082] It should be noted that AR620 color paste is a color paste containing 60 wt % titanium dioxide, which is not within the scope of protection of the present invention and is used as a control group in the examples.

[0083] Determination of infrared reflectivity and radar wave transmittance of samples 1-11

[0084] Sample preparation: prepare a PP substrate of 15*20cm*3mm, wipe the surface clean with ethanol, spray with a thickness of 20μm, bake at 80℃ for 30min, and test after leaving it for 48h.

[0085] After the sample was prepared, the UV-visible-near infrared reflectivity was tested on a HITACHI U-4100 spectrometer. Radar transmission loss was tested using a Rohde & Schwarz QAR device (free space method). Hiding power was measured using the black and white grid paper method. The results are summarized in Table 2.

[0086] Table 2 Test results of samples 1-11

[0087]

[0088]

[0089] As shown in Table 2, the addition of metal flake pigments will significantly increase the loss, while inorganic oxide flake pigments are insulators. After being mixed and added, the radar transmittance is improved. As can be seen from the results, the loss is almost not increased. At the same time, the addition of some inorganic oxide flake pigments improves the hiding rate, but only inorganic oxide flake pigments will lead to a lower infrared reflectivity of the coating, and the effect is poor.

[0090] Preparation of Dispersions for Infrared Black Transparent Colorants

[0091] 69 parts of deionized water, 10 parts of BYK190, 1 part of 10% DMEA solution, 5 parts of SETAL@6303 resin (Zhanxin Company), and 15 parts of pigment were mixed and stirred for 30 minutes, the pH was adjusted to 7.5-8.5 with a pH regulator, and then sand-milled for 1-3 hours until the fineness was less than 10 μm to prepare each dispersion. The pigments used in each dispersion were Paliogen@Red L3850, Paliogen@Red L3875, Paliotol@Yellow L0962, Paliotol@Yellow L0960, Heliogen@Blue L7085, Heliogen@BlueL6975, and Paliogen@Black L0086, respectively, to prepare Paliogen@Red L3850 dispersion, Paliogen@RedL3875 dispersion, Paliotol@Yellow L0962 dispersion, Paliotol@Yellow L0960 dispersion, and Heliogen@Blue L7085 dispersion, Heliogen@Blue L6975 dispersion, Paliogen@Black L0086 dispersion.

[0092] Preparation of infrared black transparent color paste

[0093] Infrared black transparent color paste (BC for short) is prepared by mixing according to the formula in Table 3 below.

[0094] Table 3 BC-1-4 formula

[0095] Color paste model BC-1 BC-2 BC-3 BC-4 Paliogen@Red L3850 dispersion 41.5％ 41.0％ Paliogen@Red L3875 dispersion 33.8％ 32.2％ Paliotol@Yellow L0962 dispersion 12.2％ 11.7％ Paliotol@Yellow L0960 dispersion 15.7％ 15.0％ Heliogen@Blue L7085 dispersion 46.3％ 45.8％ Heliogen@Blue L6975 dispersion 50.5％ 48.0％ Paliogen@Black L0086 dispersion 1.5％ 4.8％

[0096] Preparation of the Second Coating Composition

[0097] Second coating compositions 12-17 were prepared according to Table 4 below.

[0098] Table 4: Sample 12-17 formula

[0099]

[0100] It should be noted that AR 2000BLACK color paste is a black paste containing carbon black pigment, which is not within the scope of protection of the present invention and is used as a control group in the examples.

[0101] Determination of the second coating composition

[0102] Sample preparation: prepare a transparent glass substrate of 15*10 cm, wipe it clean with ethanol, directly spray the coating composition of the above samples 12-17 with a thickness of 15 μm, and bake at 80° C. for 20 minutes.

[0103] After the sample was prepared, the UV-visible-near infrared transmittance was tested on a HITACHI U-4100 spectrometer. The hiding power was measured using the black and white grid paper method. The optical indexes were tested using a Xrite-ci7800 colorimeter. The results are summarized in Table 5.

[0104] Table 5 Test results of samples 12-17

[0105]

[0106] As can be seen from Table 5, carbon black has almost no infrared transmittance and strong absorption; Paliogen@Black L0086 single-component dispersion also has good black appearance and infrared transmittance, but its black color deviates; the mixed black slurry has an excellent black appearance, and adding Paliogen@Black L0086 dispersion will make its black appear deeper, and the black tone is rich when observed from multiple angles.

[0107] Preparation of a first coating composition containing a transparent organic colorant

[0108] First coating composition samples 18-26 containing transparent organic colorants were prepared according to Table 6 below.

[0109] Table 6: Sample 18-26 formula

[0110]

[0111]

[0112] It should be noted that AR 2000BLACK color paste is a black paste containing carbon black pigment, which is not within the scope of protection of the present invention and is used as a control group in the examples.

[0113] The test results of samples 18-26 are shown in Table 7 below.

[0114] Table 7 Test results of samples 18-26

[0115]

[0116]

[0117] From the data in Table 7, it can be seen that adding infrared transparent black (mixed or single component) or blue pigment will not affect the reflectivity of the reflective layer, while adding a small amount of carbon black will significantly reduce the reflectivity.

[0118] Preparation of coating samples of Examples 1-13 and Comparative Examples 1-3

[0119] Based on the above samples 1-26, reflective coating samples were prepared, the method is shown in Table 8, and the formula is shown in Table 9. After the samples were prepared and placed for 48 hours, various tests were performed. The infrared irradiation heating test used Phillips Infrared Lamp (100W) for irradiation, the constant temperature laboratory was 25°C, and the distance was 20cm. The test results are shown in Tables 10 and 11.

[0120] Table 8 Preparation method

[0121]

[0122] Table 9 Formulas of Examples 1-13 and Comparative Examples 1-3

[0123]

[0124] Table 10 Test results of Examples 1-7 and Comparative Example 1

[0125]

[0126] From the results in Table 10, it can be seen that Examples 1-7 and Comparative Example 1 reflect the influence of different types of materials of the first coating and the second coating on the results. It can be seen that: the sample of Comparative Example 1 has a strong heat absorption ability, while the radar loss of Example 6 is relatively high, and Example 7 shows insufficient reflectivity; the other samples achieve a balance between infrared reflection and radar transmittance, showing better performance.

[0127] Table 11 Test results of Examples 8-13 and Comparative Examples 2-3

[0128]

[0129] It can be seen from Table 11 above that adding a colored pigment (especially black) to the first coating composition or the second coating composition will not affect the infrared reflectivity, but can deepen the black appearance to a certain extent.

[0130] The above samples were selected to further test the coating performance. From Table 12, it can be seen that the coating has excellent weather resistance.

[0131] Table 12 Test results of Examples 8-13 and Comparative Examples 2-3

[0132]

[0133]

[0134] In summary, the coating obtained by the technical solution of the present invention has high radar wave transmittance, high infrared reflection performance, and high reflection and heat insulation capabilities, and is particularly suitable for black or silver type coating systems, as well as substrates such as plastics and resin composite materials.

[0135] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A multifunctional water-based low-temperature paint double-coat structure, comprising a first coating (3) and a second coating (2), wherein the first coating (3) comprises a mixture of metal flake pigments and inorganic oxide pigments, and the second coating (2) comprises a transparent organic color paste, and the first coating coating composition used in the first coating (3) and the second coating coating composition used in the second coating (2) are both mixtures of acrylic resin emulsion and polyurethane dispersion.

2. The multifunctional water-based low-temperature coating double coating structure according to claim 1 is characterized in that: Measured by mass percentage, the first coating composition comprises: The total content of the above components is 100%.

3. The multifunctional water-based low-temperature coating double coating structure according to claim 1 is characterized in that: Measured by mass percentage, the second coating composition comprises: The total content of the above components is 100%.

4. The multifunctional water-based low-temperature coating double coating structure according to claim 2 or 3, characterized in that: The acrylic resin emulsion is selected from one or more of aqueous acrylic emulsion, polyester modified acrylic emulsion or polyurethane modified acrylic emulsion. Preferably, the acrylic resin emulsion has a hydroxyl content of 0-3%, a solid content of 20-50%, a glass transition temperature (Tg)>25°C, and a minimum film forming temperature (MFTT)>25°C; the polyurethane dispersion is selected from one or more of aqueous polyurethane dispersion, acrylic modified polyurethane dispersion, aliphatic modified polyurethane dispersion, and polyester modified polyurethane dispersion. Preferably, the polyurethane dispersion does not contain hydroxyl, has a solid content of 20-50%, a glass transition temperature (Tg)<0°C, and a minimum film forming temperature (MFTT)<5°C; the solvent comprises deionized water and a film-forming solvent added in an amount not higher than 10%, and the film-forming solvent is selected from one or more of isooctyl alcohol, isopropanol, propylene glycol, propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, diethylene glycol butyl ether, and dipropylene glycol butyl ether.

5. The multifunctional water-based low-temperature coating double coating structure according to claim 2 is characterized in that: In parts by weight, the metal flake pigment dispersion comprises: 3-15 parts of deionized water; Dispersant 0.1-1 part; 2-8 parts of metal flake pigment; The metal flake pigment is selected from one or more of silver dollar aluminum pigment, corn flake aluminum pigment, electroplated silver aluminum pigment, copper pigment, and alloy flake pigment, and the particle size of the metal flake pigment is 5-50 μm and the thickness is 10-500 nm; preferably, the metal flake pigment is a metal flake pigment with a surface coated with a modified resin or a silica modified layer; more preferably, the metal flake pigment is a silica-coated flaky aluminum silver paste.

6. The multifunctional water-based low-temperature coating double coating structure according to claim 2 is characterized in that: The inorganic oxide color paste comprises, by weight: The inorganic oxide flake pigment is selected from one or more of mica flakes, synthetic mica flakes, alumina flakes, and glass flakes, and the particle size of the inorganic oxide flake pigment is 5-50 μm and the thickness is 10-1000 nm; preferably, the inorganic oxide flake pigment is an inorganic oxide flake pigment with a surface coated with silicon dioxide, titanium dioxide, iron oxide, iron titanium oxide or iron manganese oxide; the white powder filler is selected from one or more of titanium dioxide, barium sulfate, calcium carbonate, talc, and wollastonite, and the particle size of the white powder filler is 0.1-50 μm.

7. The multifunctional water-based low-temperature coating double coating structure according to claim 2 or 3, characterized in that: The transparent organic color paste includes one or more dispersions of different colors, and the dispersions include, by weight: The preparation step of the dispersion comprises: mixing deionized water, a dispersant, a dispersing resin and a pigment for 30 minutes, adjusting the pH to 7.5-8.5 with a pH adjuster, and then sand-milling for 1-3 hours until the fineness is less than 10 μm, so as to obtain the dispersion; the pigment is selected from one or more of red pigments, yellow pigments, blue pigments and black pigments, including but not limited to one or more combinations of indanthrone, copper phthalocyanine blue pigments, YInMn indium manganese blue, perylene black pigments, perylene red pigments, non-hiding DPP red pigments, quinacridone red pigments, quinophthalone pigments, isoindolyl yellow pigments and benzimidazolone yellow-orange pigments.

8. A multifunctional water-based low-temperature paint coating system, comprising a clear coat layer (1), a second coat layer (2), a first coat layer (3) and a primer layer (4); the clear coat used in the clear coat layer (1) is an isocyanate-cured hydroxy acrylic resin composition; the primer used in the primer layer (4) is a high-solid isocyanate-cured polyamine resin two-component coating composition; the first coat layer (3) comprises a mixture of metal flake pigments and inorganic oxide pigments, the second coat layer (2) comprises a transparent organic color paste, and the first coat coating composition used in the first coat layer (3) and the second coat coating composition used in the second coat layer (2) are both mixtures comprising an acrylic resin emulsion and a polyurethane dispersion.

9. A method for preparing the multifunctional water-based low-temperature paint coating system according to claim 8, characterized in that: The steps include: S1: Preparation of the first coating composition: Open the stirring kettle, add the solvent, acrylic resin emulsion, polyurethane dispersion, metal flake pigment, inorganic oxide color paste, transparent organic color paste, wetting and leveling agent, defoaming agent, and thickener into the stirring kettle in sequence, and stir until fully mixed; adjust the pH to 7.5-8.5 with a pH adjuster to obtain the first coating composition; S2: Preparation of the second coating composition: Open the stirring kettle, add the solvent, acrylic resin emulsion, polyurethane dispersion, transparent organic color paste, wetting and leveling agent, defoaming agent, and thickener into the stirring kettle in sequence, and stir until fully mixed; adjust the pH to 7.5-8.5 with a pH adjuster to obtain the second coating composition; S3: Spraying: A first coating composition is sprayed on the surface of the primer layer (4), and flash-dried at 60-80°C for 5-10 minutes to obtain a first coating (3); a second coating composition is continuously sprayed on the surface of the first coating (3), and dried at 60-80°C for 10-30 minutes to obtain a second coating (2); a clear coat is sprayed on the surface of the second coating (2), and cured at 60-100°C for 30-120 minutes to form a clear coat layer (1), thereby obtaining the multifunctional water-based low-temperature coating system.

10. An application of the multifunctional water-based low-temperature paint coating system as claimed in claim 8, including applications in the fields of aircraft, automobiles, and smart devices.

Images