Double coating structure based on multifunctional water-based low-temperature paint, and coating system based on multifunctional water-based low-temperature paint and use thereof

Abstract

A double coating structure based on a multifunctional water-based low-temperature paint, and a coating system and the use thereof. The double coating structure comprises a first coating and a second coating, wherein the first coating comprises a mixture of a flaky metallic pigment and an inorganic oxide pigment; the second coating comprises a transparent organic color paste; and 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 an acrylic resin emulsion and a polyurethane dispersion. The double coating structure uses the technical solution of a pigment mixture and does not contain any curing agent such as an isocyanate; the obtained double coating structure has high radar wave transmission performance, high infrared reflection performance and high reflective insulation capacity, and is particularly suitable for black or silver paint systems; and since a water-based low-temperature paint is used, the double coating structure has the characteristics of significant low-temperature quick-drying film formation, a thin coating and a low VOC content, and can realize a coating process that has low energy consumption and is healthy and environmentally friendly.

Description

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

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

[0002] With the rapid development of emerging fields such as autonomous driving and low-altitude flight, there are higher requirements for surface coating of devices in fields such as aircraft, automobiles and intelligent devices. For example, in terms of function, it is desired to realize high radar wave transmission while having high infrared reflection and heat insulation performance, thereby enhancing the safety of the device, reducing the energy loss of the device and improving the comfort of riding. Therefore, coatings with radar wave transmission function, functional coatings that enhance the infrared reflection signal of laser radar, and functional coatings that reflect and insulate heat are receiving more and more attention.

[0003] However, since the most popular coatings such as black and silver often need to add black pigments or aluminum effect pigments to achieve metallic texture and color depth, this will result in a large amount of absorption of infrared light, causing difficulty in identifying laser radar signals and a significant increase in surface temperature, or the inability to transmit 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 high reflection intensity for laser signals, which still has high reflection intensity for laser radar signals when the incident angle gradually increases; patent CN116410628A discloses a multi-layer structure coating system with strong near-infrared reflection performance, which has stronger reflection performance for detection signals using near-infrared wavebands; and patent CN116162363A discloses a radar frequency transparent effect pigment mixture, which forms a coating that can improve radar transmission rate. However, as known from the above, the known related technologies are only coatings with single functions such as high radar wave transmission, high infrared reflection and high reflection insulation, and have defects in realizing multifunctional applications, which cannot meet the requirements in actual applications. At the same time, some technologies also need to enhance the thickness of the primer layer, and the application effect of some technologies on some substrates (such as carbon fibers) will be greatly reduced.

[0005] In summary, there is an urgent need in the art to develop a water-based low-temperature coating double-coating structure that can simultaneously have functions such as high radar wave transmission, high infrared reflection and high reflection insulation, in order to solve the problems in the prior art. SUMMARY

[0006] Based on the above facts, the purpose of the present application is to provide a multifunctional water-based low-temperature coating double-coating structure, and a multifunctional water-based low-temperature coating coating system using the double-coating structure. The multifunctional water-based low-temperature coating double-coating structure uses a mixed pigment technical solution, does not contain isocyanate, amino resin, polyamine resin and other curing agents, and the obtained double-coating structure has high radar wave transmission performance, high infrared reflection performance, high reflection heat insulation capacity, infrared reflectivity (780-2500nm) is greater than 60%, radar wave transmission loss increase value is less than 0.5dB, and is particularly suitable for black type or silver type coating system. In addition, the double-coating structure of the present application uses water-based low-temperature coating, has the characteristics of low-temperature fast drying film forming, thin coating and low VOC, and can realize low energy consumption, health and environmental protection of the coating process.

[0007] The first aspect of the present application provides a multifunctional water-based low-temperature coating double-coating structure, comprising a first coating layer and a second coating layer, the first coating layer comprises a mixture of metal flaky pigment and inorganic oxide pigment, and the second coating layer comprises transparent organic color paste, the first coating layer uses a first coating layer coating composition, and the second coating layer uses a second coating layer coating composition, both of which are mixtures comprising acrylic resin emulsion and polyurethane dispersion.

[0008] The first coating layer coating composition

[0009] In some embodiments of the present application, the first coating layer coating composition comprises, by mass percentage:

[0010] The content of each component above accounts for 100%.

[0011] Preferably, the amount of the metal flaky pigment dispersion is 1-3wt%, and further preferably 1-2wt%.

[0012] The second coating layer coating composition

[0013] In some embodiments of the present application, the second coating layer coating composition comprises, by mass percentage:

[0014] The content of each component above accounts for 100%.

[0015] The acrylic resin emulsion

[0016] In the present application, the acrylic resin emulsion contained in the first coating composition, the second coating composition is selected from self-crosslinking or low hydroxyl content resin, which is substantially transparent in the near infrared range of 780nm-2500nm, and has no effect on the reflectivity or transmittance of infrared itself, and does not need to add curing agent. Preferably, the acrylic resin emulsion is selected from one or more of the following: an aqueous acrylic emulsion, a polyester modified acrylic emulsion or a polyurethane modified acrylic emulsion with a hydroxyl content of 0-3%, a solid content of 20-50%, a glass transition temperature (Tg) > 25℃, and a minimum film formation temperature (MFTT) > 25℃. The use of a mixture of acrylic resin emulsion and polyurethane dispersion in a suitable ratio can exhibit better adhesion, flexibility and film forming effect.

[0017] Specifically, the acrylic resin emulsion is selected from one or more of the following: SETAQUA@6801, SETAQUA@6802 provided by Zhenxin Resin Co., Ltd., Bayhydrol@A2846, Bayhydrol@A2474, Bayhydrol@A2457, Bayhydrol@A2856xp, Bayhydrol@A2469 provided by Covestro Resin Co., Ltd., WD-594, WD-588 provided by DIC Resin Co., Ltd., Joncryl@8330AP, Joncryl@8111AP, Joncryl@HYB 6336, Joncryl@HYB 6340, Joncryl@HYB 6345AP provided by BASF Resin Co., Ltd.

[0018] Polyurethane dispersion

[0019] In the present application, the polyurethane dispersion contained in the first coating composition, the second coating composition is selected from one or more of the following: an aqueous polyurethane dispersion, an acrylic modified polyurethane dispersion, an aliphatic modified polyurethane dispersion, a polyester modified polyurethane dispersion, which does not contain hydroxyl, has a solid content of 20-50%, a glass transition temperature (Tg) <0℃, and a minimum film formation temperature (MFTT) <5℃. The use of a mixture of acrylic resin emulsion and polyurethane dispersion in a suitable ratio can exhibit better adhesion, flexibility and film forming effect.

[0020] Specifically, the polyurethane dispersion is selected from one or more of the polyurethane dispersions provided by BASF under the trade designation Joncryl@ U 4190, Joncryl@ U 5168, Joncryl@ U 4199AP, DIC under the trade designation WATERSOL UD-5002, WATERSOL UD-8801, Covestro under the trade designation Bayhydrol@ UH2648, Bayhydrol@ UH2648 / 1, Bayhydrol@ UH2606, Bayhydrol@ UH2952, Bayhydrol@ UA2856, Zannan Resin under the trade designation DAOTAN VTW6460, DAOTAN VTW6462, DAOTAN VTW6464.

[0021] Metal flaky pigment dispersion

[0022] In the present application, the metal flaky pigment dispersion comprises, by weight parts:

[0023] Deionized water 3-15 parts;

[0024] Dispersant 0.1-1 part;

[0025] Metal flaky pigment 2-8 parts;

[0026] The metal flaky pigment is selected from one or more of silver dollar type aluminum pigments, cornflake type aluminum pigments, electroplated silver aluminum pigments, copper pigments, alloy flaky pigments, has a particle size of 5-50 μm and a thickness of 10-500 nm. The metal flaky pigment has excellent hiding power and good infrared reflection ability. Although a good electrically conductive metal pigment can also cause loss to radar waves, the loss can be reduced to a low level through the design of the present application.

[0027] In some preferred embodiments of the present application, the metal flaky pigment is a metal flaky pigment coated with a modified resin or a modified layer of silicon dioxide; more preferably, the metal flaky pigment is a silicon dioxide coated flaky aluminum silver paste.

[0028] Specifically, the aluminum silver paste includes but is not limited to one or more of the aluminum silver pastes provided by Eka under the trade designation STAPA HYDROLAN series 2153, 2154, 2156, 2197, 2192, S422, HYDROSHINE WS series 3001, 3004, METALURE series 1006, SBC AQ J series 6713, 6718, 6812, 6834 provided by Star Platinum Union, Zuxing under the trade designation ZW6120, ZW6113, ZW6130, etc.

[0029] Inorganic oxide color paste

[0030] In the present application, the inorganic oxide color paste comprises, by weight parts:

[0031] The inorganic oxide flaky pigment is a special pigment with high brightness and goniochromatic effect, which can be adjusted in size according to product requirements, thereby realizing different brightness, hiding power and goniochromatic effect.

[0032] In some embodiments of the present application, the inorganic oxide flaky pigment is selected from one or more of mica flake, synthetic mica flake, alumina flake, glass flake, the particle size of the inorganic oxide flaky pigment is 5-50 μm, the thickness is 10-1000 nm, preferably, the inorganic oxide flaky pigment is an inorganic oxide flaky pigment coated with silica, 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, wollastonite, the particle size of the white powder filler is 0.1-50 μm.

[0033] Specifically, the inorganic oxide flaky pigment includes but is not limited to one or more of the inorganic oxide flaky pigments provided by Kuncai Technology with model numbers SM015, SM525, SM025, iriodin series 9602, 9605, 9612, 9121, 9119 provided by Merck, xirallic series T61-10WNT microsilver, T60-10WNT crystalsilver, OEM OPAQUE SILVER, OEM silver series provided by Eka, etc.; the white powder filler is selected from one or more of titanium dioxide provided by Ishihara with model numbers Tipaque CR-97, Tipaque FR404, Tipaque R930.

[0034] Transparent organic color paste

[0035] In the present application, the transparent organic color paste comprises one or more dispersions of different colors, the dispersion comprises, by weight parts:

[0036] The preparation steps of the dispersion include: mixing and stirring deionized water, dispersant, dispersing resin, pigment for 30 min, adjusting pH to 7.5-8.5 with pH regulator, and then sand grinding for 1-3 h to fineness less than 10 μm, to obtain the dispersion; the pigment is selected from one or more of red pigment, yellow pigment, blue pigment, black pigment, including but not limited to a combination of one or more of indathrene, phthalocyanine copper-based blue pigment, YInMn indium manganese blue, perylene black pigment, perylene red pigment, non-hiding DPP red pigment, quinacridone-based red pigment, quinophthalone-based pigment, isoindolinone pigment, and benzimidazolone-based yellow-orange pigment.

[0037] Specifically, the red pigment is selected from one or more of red pigments with model numbers Paliogen@Red L3850, Paliogen@Red L3875, Paliogen@Red L3885, Paliogen@Red L4045 provided by BASF, Germany; the yellow pigment is selected from one or more of yellow pigments with model numbers Paliotol@Yellow L0962, Paliotol@Yellow L0960, Paliotol@Yellow L1155, Sicopal@Yellow L1130, Sicopal@Yellow L1100, Sicopal@Yellow L1635 provided by BASF, Germany; the blue pigment is selected from one or more of blue pigments with model numbers Heliogen@Blue L7085, Heliogen@Blue L6975, Heliogen@Blue L6930 Heliogen@Blue L7081 provided by BASF, Germany; the black pigment is selected from one or more of black pigments with model numbers Paliogen@Black L0086, Paliogen@Black L0095 provided by BASF, Germany or a combination thereof. The dispersing resin is selected from SETAL@6303 resin of Zannan Company, Joncryl@62J of BASF, ACW-1011 of Ruiqiao Automobile Company, and preferably SETAL@6303 resin of Zannan Company. The dispersant is selected from one or more of dispersants with model numbers 190, 192, 180, 2012, 2014 provided by BYK Company, and Dispex series ULTRAPX 4550, 4522, 4525, 4575 provided by BASF.

[0038] Wetting and leveling agent

[0039] In some embodiments of the present application, the wetting and leveling agent is selected from one or more of the wetting and leveling agents with model numbers 347, 349, 3451, 381, 3560, 3455 provided by BYK Company, and hydropalat® WE series 3179, 3189, 3220, 3225, 3229 provided by BASF Company.

[0040] Defoaming agent

[0041] In some embodiments of the present application, the defoaming agent is selected from one or more of the defoaming agents with model numbers 011, 024, 015, 028, 1710 provided by BYK Company, and Foamaster series SI2281, SI2210, SI2299 provided by BASF Company.

[0042] Thickening agent

[0043] In some embodiments of the present application, the thickening agent is selected from one or more of the thickening agents with model numbers AQUATIX 8421, LAPONITE-RD, RHEOBYK-440, RHEOBYK-7420 provided by BYK Company, and Rheovis series HS1212, HS1303, AS1130, AS1189, PU1235, PU1250 provided by BASF Company. Among them, LAPONITE-RD is pre-dispersed into a 3% aqueous solution for use.

[0044] pH adjuster

[0045] In some embodiments of the present application, the pH adjuster is a 10% dimethyl ethanolamine solution (DMEA).

[0046] Solvent

[0047] In some embodiments of the present application, the solvent is mainly deionized water, and a film-forming solvent with a mass percentage of not more than 10% can also be added. The film-forming solvent is selected from one or more of isooctanol, isopropyl alcohol, propylene glycol, propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ether, diethylene glycol butyl ether, and dipropylene glycol butyl ether.

[0048] The second aspect of the present application provides a multifunctional water-based low-temperature 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 metallic flaky pigments and inorganic oxide pigments, the second coating layer comprises 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 acrylic resin emulsion and polyurethane dispersion.

[0049] Varnish

[0050] In the present application, the viscosity of the varnish ranges from 100 to 5000 mPa·s, and preferably is the RALON varnish provided by RALON Company with model number C7900.

[0051] Primer

[0052] In the present application, the solid content of the primer is greater than 70%, and the viscosity ranges from 100 to 20000 mPa·s; and preferably is the RALON primer provided by RALON Company with model number P7001.

[0053] The third aspect of the present application provides a method for preparing the multifunctional water-based low-temperature coating system of the second aspect of the present application, comprising the following steps:

[0054] S1: preparing a first coating layer coating composition:

[0055] Open the stirring kettle, and sequentially add solvent, acrylic resin emulsion, polyurethane dispersion, metallic flaky pigments, inorganic oxide color paste, transparent organic color paste, wetting and leveling agent, defoaming agent and thickening agent into the stirring kettle, and stir until fully mixed; adjust the pH to 7.5-8.5 using a pH adjuster, and the first coating layer coating composition is obtained;

[0056] S2: preparing a second coating layer coating composition:

[0057] Open the stirring kettle, and sequentially add solvent, acrylic resin emulsion, polyurethane dispersion, transparent organic color paste, wetting and leveling agent, defoaming agent and thickening agent into the stirring kettle, and stir until fully mixed; adjust the pH to 7.5-8.5 using a pH adjuster, and the second coating layer coating composition is obtained;

[0058] S3: spraying:

[0059] Spray the first coating composition on the surface of the primer layer, flash dry at 60-80℃ for 5-10min, to obtain the first coating layer; continue to spray the second coating composition on the surface of the first coating layer, and dry at 60-80℃ for 10-30min to obtain the second coating layer; spray the varnish on the surface of the second coating layer, and cure at 60-100℃ for 30-120min to form the varnish layer, thereby obtaining the multifunctional water-based low-temperature coating layer system.

[0060] The fourth aspect of the present application provides an application of the multifunctional water-based low-temperature coating layer system according to the second aspect of the present application, including applications in the fields of aircrafts, automobiles and intelligent devices.

[0061] The present application has the following beneficial effects:

[0062] The present application provides a multifunctional water-based low-temperature coating double-coating structure, which adopts a mixed pigment technical solution and does not contain curing agents such as isocyanate, amino resin, polyamine resin, etc., and the obtained double-coating structure has high radar wave transmission performance, high infrared reflection performance and high reflection heat insulation capacity, with an infrared reflectivity (780-2500nm) of greater than 60%, and a radar wave transmission loss increase value of less than 0.5dB, and is particularly suitable for black type or silver type coating systems. In addition, the double-coating structure adopts water-based low-temperature coating, has the characteristics of low-temperature fast-drying film formation, thin coating layer and low VOC, and can realize low energy consumption and health and environmental protection in the coating process. BRIEF DESCRIPTION OF DRAWINGS

[0063] Fig. 1 is a schematic diagram of the multifunctional water-based low-temperature coating double-coating structure according to the present application.

[0064] Fig. 2 is a schematic diagram of the multifunctional water-based low-temperature coating layer system according to the present application coated on a substrate.

[0065] The numbers in the figures respectively represent: 1. varnish layer; 2. second coating layer; 3. first coating layer; 4. primer layer; 5. substrate. DETAILED DESCRIPTION

[0066] In order to more clearly illustrate the present application, the present application will be further described below in combination with specific examples and comparative examples. It should be understood by those skilled in the art that the specific descriptions below are illustrative rather than limiting, and should not limit the protection scope of the present application. The experimental methods used in the following examples and comparative examples are conventional methods, and the raw materials and reagents used are products that can be purchased from conventional commercial channels, unless otherwise specified.

[0067] The above technical solutions will be described below in combination with specific examples.

[0068] Preparation of metal flaky pigment dispersion

[0069] STAPA HYDROLAN 2192 dispersion, HYDROSHINE WS 3001 dispersion, ZW6120 dispersion, SBC AQ J6713 dispersion were prepared by using STAPA HYDROLAN 2192, HYDROSHINE WS 3001, ZW6120, SBC AQ J6713 aluminum paste respectively, 5 parts of deionized water, 0.5 parts of BYK192, 5 parts of aluminum paste were mixed uniformly at low speed, and placed for 2h for standby.

[0070] Inorganic oxide color paste preparation

[0071] SM015, iriodin 9612, OEM OPAQUE SILVER, iriodin 9119 inorganic oxide flaky pigment were selected respectively, 5 parts of deionized water, 0.5 parts of BYK190, 5 parts of inorganic oxide flaky pigment were mixed uniformly at low speed, and placed for 2h for standby, and SM015 color paste, iriodin 9612 color paste, OEM OPAQUE SILVER color paste, iriodin 9119 color paste were prepared respectively.

[0072] Preparation of first coating composition without transparent organic color paste

[0073] The first coating composition samples 1-11 without transparent organic color paste were prepared according to the following Table 1.

[0074] Table 1 Formulation of samples 1-11

[0075] It should be noted that the AR620 color paste is a color paste containing 60wt% titanium dioxide, which is not within the protection scope of the present application, and is used as a control group in the examples.

[0076] Determination of infrared reflectivity and radar wave transmittance of samples 1-11

[0077] Sample preparation: PP substrate 15*20cm*3mm was prepared, the surface was wiped clean with ethanol, the spraying thickness was 20μm, and the sample was baked at 80℃ for 30min, and then tested after standing for 48h.

[0078] After the sample preparation was completed, the ultraviolet-visible-near infrared reflectivity was tested on a HITACHI U-4100 spectrometer. The radar transmittance loss was tested using a Rohde & Schwarz QAR device (free space method). The hiding power was determined by black and white grid paper method. The results are summarized in the following Table 2.

[0079] Table 2 Test results of samples 1-11

[0080] From the above Table 2, it can be seen that the addition of metallic flake pigments significantly increases the loss, while the inorganic oxide flake pigments are insulators, and the addition of which improves the radar transmittance, and the results show that the loss is hardly increased. At the same time, the addition of some inorganic oxide flake pigments improves the hiding power, but only the inorganic oxide flake pigments result in a lower infrared reflectance of the coating and a poor effect.

[0081] Preparation of dispersions for infrared black transparent color paste

[0082] 69 parts of deionized water, 10 parts of BYK190, 1 part of 10% DMEA solution, 5 parts of SETAL@6303 resin (Zhenxin Company), and 15 parts of pigments were mixed and stirred for 30 min, and then a pH adjuster was used to adjust the pH to 7.5-8.5, followed by sanding for 1-3 h until the fineness was less than 10 μm, to prepare the dispersions, and the pigments used in the dispersions were Paliogen@Red L3850, Paliogen@Red L3875, Paliotol@Yellow L0962, Paliotol@Yellow L0960, Heliogen@Blue L7085, Heliogen@Blue L6975, and Paliogen@Black L0086, respectively, to prepare Paliogen@Red L3850 dispersion, Paliogen@Red L3875 dispersion, Paliotol@Yellow L0962 dispersion, Paliotol@Yellow L0960 dispersion, Heliogen@Blue L7085 dispersion, Heliogen@Blue L6975 dispersion, and Paliogen@Black L0086 dispersion, respectively.

[0083] Preparation of infrared black transparent color paste

[0084] The infrared black transparent color paste (referred to as BC) was prepared by mixing according to the following Table 3.

[0085] Table 3 BC-1-4 formulation table

[0086] Preparation of second coating composition

[0087] The second coating compositions 12-17 were prepared according to the following Table 4.

[0088] Table 4 Sample 12-17 formulation table

[0089] AR 2000 BLACK color paste is a black color paste containing carbon black pigment, which is not within the protection scope of the present application, and is used as a control group in the examples.

[0090] Determination of the second coating composition

[0091] Sample preparation: Prepare a transparent glass substrate 15*10 cm, wipe clean with ethanol, and directly spray the above-mentioned sample 12-17 coating composition at a thickness of 15 μm, and bake at 80°C for 20 min.

[0092] After the sample preparation is completed, the ultraviolet-visible-near infrared transmittance is tested on a HITACHI U-4100 spectrometer. The hiding power is determined by the black and white grid paper method. The optical index is tested by an Xrite-ci7800 colorimeter. The results obtained are summarized in Table 5 below.

[0093] Table 5 Test results of samples 12-17

[0094] 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 is slightly deviated; the mixture black color paste has excellent black appearance, and the addition of Paliogen@Black L0086 dispersion makes the black color appear darker, and the black tone is rich in multi-angle observation.

[0095] Preparation of the first coating composition containing transparent organic color paste

[0096] The first coating composition containing transparent organic color paste samples 18-26 are prepared according to Table 6 below.

[0097] Table 6 Formulation table of samples 18-26

[0098] AR 2000 BLACK color paste is a black color paste containing carbon black pigment, which is not within the protection scope of the present application, and is used as a control group in the examples.

[0099] The test results of samples 18-26 are shown in Table 7 below.

[0100] Table 7 Test results of samples 18-26

[0101] As can be seen from the data in Table 7, the addition of infrared transparent black (mixed or single-component) or blue pigment does not affect the reflectivity of the reflective layer, and the addition of a small amount of carbon black greatly reduces the reflectivity.

[0102] Preparation of coating sample plates of examples 1-13 and comparative examples 1-3

[0103] The reflective coating sample plates were prepared based on the above samples 1-26 according to the method shown in Table 8 and the formula shown in Table 9. After the sample plates were prepared and placed for 48 h, various tests were performed. The infrared irradiation heating test used a Phillips Infrared Lamp (100 W) for irradiation, and the constant temperature laboratory was 25℃, with a distance of 20 cm. The test results are shown in Tables 10 and 11.

[0104] Table 8 preparation method

[0105] Table 9 formula of examples 1-13 and comparative examples 1-3

[0106] Table 10 test results of examples 1-7 and comparative example 1

[0107] As can be seen from the results in Table 10, examples 1-7 and comparative example 1 show 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 plate of comparative example 1 has strong heat absorption capacity, the radar loss of example 6 is high, and example 7 shows insufficient reflectivity; the other sample plates achieve a balance between infrared reflectivity and radar transmittance, and show good performance.

[0108] Table 11 test results of examples 8-13 and comparative examples 2-3

[0109] As can be seen from the above Table 11, the addition of colored pigments (especially black) in the first coating composition or the second coating composition does not affect the infrared reflectivity, and can darken the appearance to a certain extent.

[0110] The above sample plates were selected for further testing of coating performance, and as can be seen from Table 12, the coating has excellent weather resistance.

[0111] Table 12 test results of examples 8-13 and comparative examples 2-3

[0112] In summary, the coating obtained by the technical scheme of the present application has high radar wave transmittance, high infrared reflectivity, and high reflective heat insulation capacity, and is particularly suitable for black type or silver type coating systems, as well as plastic, resin composite materials and other substrates.

[0113] Obviously, the above embodiments of the present application are merely exemplary and are not intended to limit the present application. Based on the above description, other variations or changes can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A multifunctional waterborne low temperature coating dual coating structure, comprising a first coating (3) and a second coating (2), the first coating (3) comprises a mixture of metallic flaky pigments and inorganic oxide pigments, the second coating (2) comprises transparent organic color paste, the first coating (3) uses a first coating composition and the second coating (2) uses a second coating composition, both of which are a mixture comprising acrylic resin emulsion and polyurethane dispersion.

2. The multifunctional aqueous low temperature paint two-coat structure according to claim 1, characterized in that, The first coating composition comprises, by mass percentage: The content of each component above accounts for 100%.

3. The multifunctional aqueous low temperature paint two-coat structure according to claim 1, characterized by, The second coating composition comprises, by mass percentage: The content of each component above accounts for 100%.

4. The multifunctional aqueous low temperature paint two-coat structure according to claim 2 or 3, characterized in that, The acrylic resin emulsion is selected from one or more of waterborne 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℃, and a minimum film formation temperature (MFTT) > 25℃; the polyurethane dispersion is selected from one or more of waterborne polyurethane dispersion, acrylic modified polyurethane dispersion, aliphatic modified polyurethane dispersion, polyester modified polyurethane dispersion, preferably, the polyurethane dispersion is free of hydroxyl groups, has a solid content of 20-50%, a glass transition temperature (Tg) < 0℃, and a minimum film formation temperature (MFTT) < 5℃; the solvent includes deionized water and a film forming solvent in an amount of not more than 10%, the film forming solvent is selected from one or more of isooctanol, isopropyl alcohol, 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 aqueous low temperature paint double coating structure according to claim 2, characterized by, The metallic flaky pigment dispersion includes, by weight parts: Deionized water 3-15 parts; Dispersant 0.1-1 part; Metallic flaky pigment 2-8 parts; The metallic flaky pigment is selected from one or more of silver dollar type aluminum pigments, corn flake type aluminum pigments, electroplated silver aluminum pigments, copper pigments, and alloy flaky pigments, the particle size of the metallic flaky pigment is 5-50μm, and the thickness is 10-500nm; preferably, the metallic flaky pigment is a metallic flaky pigment coated with a modified resin or a silica modified layer; more preferably, the metallic flaky pigment is a silica coated flaky aluminum silver paste.

6. The multifunctional aqueous low temperature paint double coating structure according to claim 2, characterized by, The inorganic oxide colorant includes, by weight parts: The inorganic oxide flaky pigment is selected from one or more of mica flakes, synthetic mica flakes, aluminum oxide flakes, and glass flakes, the particle size of the inorganic oxide flaky pigment is 5-50μm, and the thickness is 10-1000nm; preferably, the inorganic oxide flaky pigment is an inorganic oxide flaky pigment coated with silica, 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, the particle size of the white powder filler is 0.1-50μm.

7. The multifunctional aqueous low temperature paint two-coat structure according to claim 2 or 3, characterized in that, The transparent organic colorant paste comprises one or more dispersions of different colors, the dispersions comprising, by weight parts: The preparation steps of the dispersion include: mixing and stirring deionized water, dispersant, dispersing resin, pigment for 30 min, adjusting pH to 7.5-8.5 with pH regulator, and sanding for 1-3 h to fineness less than 10 μm, to obtain the dispersion; the pigment is selected from one or more of red pigment, yellow pigment, blue pigment, black pigment, including but not limited to a combination of one or more of indathrene, phthalocyanine copper-based blue pigment, YInMn indium manganese blue, perylene-based black pigment, perylene-based red pigment, non-hiding DPP red pigment, quinacridone red pigment, quinophthalone pigment, isoindole yellow pigment, and benzimidazolone yellow-orange pigment.

8. A multifunctional water-based low-temperature coating system, comprising a varnish layer (1), a second coating layer (2), a first coating layer (3) and a primer layer (4); the varnish used in the varnish layer (1) is an isocyanate-cured hydroxyl acrylate resin composition; the primer used in the primer layer (4) is a high-solid isocyanate-cured polyamine resin two-component coating composition; the first coating layer (3) comprises a mixture of metal flaky pigment and inorganic oxide pigment, the second coating layer (2) comprises transparent organic color paste, and the first coating layer (3) and the second coating layer (2) both use a mixture comprising an acrylic resin emulsion and a polyurethane dispersion.

9. A process for the production of a multifunctional aqueous low temperature coating system according to claim 8, characterized in that The method comprises the following steps: S1: preparing a first coating layer coating composition: Open the stirring kettle, and sequentially add solvent, acrylic resin emulsion, polyurethane dispersion, metal flaky pigment, inorganic oxide color paste, transparent organic color paste, wetting and leveling agent, defoaming agent, and thickening agent into the stirring kettle, and stir until fully mixed; adjust pH to 7.5-8.5 with a pH regulator, to obtain the first coating layer coating composition; S2: preparing a second coating layer coating composition: Open the stirring kettle, and sequentially add solvent, acrylic resin emulsion, polyurethane dispersion, transparent organic color paste, wetting and leveling agent, defoaming agent, and thickening agent into the stirring kettle, and stir until fully mixed; adjust pH to 7.5-8.5 with a pH regulator, to obtain the second coating layer coating composition; S3: spraying: Spray the first coating layer coating composition on the surface of the primer layer (4), flash dry at 60-80℃ for 5-10 min, to obtain the first coating layer (3); continue to spray the second coating layer coating composition on the surface of the first coating layer (3), and bake at 60-80℃ for 10-30 min, to obtain the second coating layer (2); spray varnish on the surface of the second coating layer (2), and cure at 60-100℃ for 30-120 min, to form the varnish layer (1), to obtain the multifunctional water-based low-temperature coating system.

10. Use of the multifunctional water-based low-temperature coating system according to claim 8, which is applied in the fields of aircraft, automobile and intelligent device.

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